JP2023017527A - Photocurable adhesive sheet - Google Patents

Abstract

To provide a photocurable adhesive sheet suitably usable as a sealant for a self-luminous type display device such as mini/micro LED display devices, etc., excellent in reworkability, and difficult to cause a removal of the sealant in a use environment of the self-luminous type display device.SOLUTION: A photocurable adhesive sheet 10 is provided. The photocurable adhesive sheet 10 includes an adhesive layer 1 curable by a radiation exposure. The adhesive layer 1 has a 180° peel force of 11 N/20 mm or less after exposure to a high-pressure mercury lamp.SELECTED DRAWING: Figure 1

Description

The present invention relates to a photocurable pressure-sensitive adhesive sheet. More particularly, it relates to a photocurable pressure-sensitive adhesive sheet suitable for encapsulating optical semiconductor elements of self-luminous display devices such as mini/micro LEDs.

In recent years, self-luminous display devices typified by mini/micro LED display devices (Mini/Micro Light Emitting Diode Displays) have been devised as next-generation display devices. Mini/micro LED display devices are basically composed of a display panel in which a large number of very small optical semiconductor elements (LED chips) are arranged in a high density. It is sealed, and a cover member such as a resin film or a glass plate is laminated on the outermost layer (see, for example, Patent Document 1).

In self-luminous display devices such as mini/micro LED display devices, there are several methods such as a white backlight method, a white light emission color filter method, and an RGB method. Since the semiconductor elements are arranged on the mounting substrate, there is a problem in that failure of the mounting causes non-lighting, different colors, chipping, misalignment, and the like of the optical semiconductor elements, resulting in a decrease in yield. Further, when the display panel is sealed, mistakes such as wrinkling, contamination by foreign matter, and air bubbles may occur. If such a yield reduction or sealing mistake occurs, rather than discarding the display panel because it is expensive, the sealing material should be peeled off and removed from the display panel, and if necessary, the defective part should be repaired. So-called rework is being carried out for reuse. Moreover, even in a self-luminous display device manufactured as an acceptable product, when a failure such as non-lighting of an optical semiconductor element occurs, it is desired to repair by peeling and removing the encapsulant.

In the above rework, the sealing material can be easily peeled off from the display panel so that the optical semiconductor element is not damaged during peeling, and the characteristic that the sealing material does not remain on the display panel after peeling (hereinafter referred to as " "reworkability") is required. As a peeling method with excellent reworkability, a photo-curing adhesive sheet is used, and the adhesive sheet is cured and shrunk by irradiating light such as ultraviolet rays, reducing the anchor effect with the adherend and improving reworkability. A method for improving is known (see, for example, Patent Document 2).

JP 2019-204905 A JP 2021-031594 A

The photocurable pressure-sensitive adhesive sheet of Patent Document 2 contains an acrylic resin, a cross-linking agent, a photopolymerization initiator, and the like, and the photopolymerization initiator is cleaved by the action of light to generate radicals and cure proceeds. , to form a crosslinked structure to promote cure shrinkage. However, when a photocurable adhesive sheet as in Patent Document 2 is used as a sealing material for a self-luminous display device, even if the self-luminous display device is manufactured as an acceptable product and does not require rework, it can be used. In the environment, there was a problem that peeling of the sealing material occurred. This is because ultraviolet light contained in outside light or light emitted from a blue optical semiconductor element cleaves a portion of the photopolymerization initiator to generate radicals, which promotes curing shrinkage of the adhesive sheet.

The present invention was conceived under the circumstances as described above, and an object of the present invention is to provide a sealing material suitable for use as a sealing material for self-luminous display devices such as mini/micro LED display devices. Another object of the present invention is to provide a photocurable pressure-sensitive adhesive sheet which is excellent in reworkability and in which peeling of the encapsulant is unlikely to occur in the use environment of a self-luminous display device.
Another object of the present invention is to provide the above-described photocurable adhesive sheet, to prevent peeling of the sealing material in a usage environment, and to repair the sealing material by peeling the sealing material with good reworkability in the event of a failure. It is an object of the present invention to provide an optical semiconductor device, a self-luminous display device, and an image display device capable of

As a result of intensive studies to achieve the above object, the present inventors have found that a photocurable pressure-sensitive adhesive sheet in which a curing reaction proceeds by a light source containing a wavelength that is not included in external light or light emitted from a blue optical semiconductor element is self-produced. It has been found that when used as a sealing material for a light-emitting display device, the sealing material is excellent in reworkability and is less likely to peel off in the environment in which the self-light-emitting display device is used. The present invention has been completed based on these findings.

A first aspect of the present invention provides a photocurable pressure-sensitive adhesive sheet. The photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention can be suitably used as a sealing material for self-luminous display devices such as mini/micro LEDs. In the self-luminous display device, there is a problem that non-lighting, different colors, chipping, misalignment, etc. of the optical semiconductor elements occur, resulting in a decrease in yield. Further, when the display panel is sealed, mistakes such as wrinkling, contamination by foreign matter, and air bubbles may occur. When such a yield reduction or sealing error occurs, so-called rework is performed in which the sealing material is peeled off from the display panel, removed, and reused.

The photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention has a pressure-sensitive adhesive layer that is cured by irradiation, and the pressure-sensitive adhesive layer has a 180° peeling force of 11 N/20 mm or less after irradiation with a high-pressure mercury lamp. be. In this configuration, when the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention is used as a sealing material for a self-luminous display device, if a decrease in yield or a sealing error occurs, after irradiation with a high-pressure mercury lamp The adhesive layer (sealing material) of the curing shrinkage reduces the anchor effect with the substrate of the display panel and the optical semiconductor element, so that it can be easily peeled off, and the sealing material remains on the display panel after peeling. In other words, the encapsulant can be peeled off with excellent reworkability. In addition, when a failure such as non-lighting of the optical semiconductor element occurs in the self-luminous display device, the adhesive layer is peeled off and removed with good reworkability by irradiating the adhesive layer with a high-pressure mercury lamp for repair. It is also preferable in that it can be done.

In the photocurable pressure-sensitive adhesive sheet according to the first aspect of the present invention, the pressure-sensitive adhesive layer preferably has a rate of change in 180° peel strength before and after UV-LED irradiation of 10% or less. In a self-luminous display device using the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention as a sealing material, this configuration is included in external light in the usage environment and light emitted from the blue optical semiconductor element. This is preferable in that it can prevent the pressure-sensitive adhesive layer (sealing material) from peeling off from the display panel due to curing shrinkage of the pressure-sensitive adhesive layer due to ultraviolet rays.

In the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention, the pressure-sensitive adhesive layer preferably has a tensile storage modulus (E'a25) at 25°C after irradiation with a high-pressure mercury lamp of 400 kPa or more. With this configuration, when the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention is used as a sealing material for an optical semiconductor element of a self-luminous display device, if a decrease in yield or a sealing mistake occurs, high pressure This is preferable in that the reworkability of the pressure-sensitive adhesive layer (sealing material) after irradiation with a mercury lamp is improved.

In the photocurable pressure-sensitive adhesive sheet according to the first aspect of the present invention, the maximum transmittance of the pressure-sensitive adhesive layer at a wavelength of 200 to 400 nm is preferably 5% or more. This configuration is preferable in that the pressure-sensitive adhesive layer can be cured and shrunk by irradiation with the high-pressure mercury lamp, thereby improving reworkability.

In the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention, the pressure-sensitive adhesive layer has a ratio of tensile storage modulus (E'a25: kPa) at 25°C after irradiation with a high-pressure mercury lamp to thickness (μm) ( kPa/μm) is preferably 1-50. This configuration is preferable in terms of adjusting the reworkability according to the thickness of the pressure-sensitive adhesive layer.

In the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention, it is preferable that the light emitted from the high-pressure mercury lamp includes radiation with a wavelength of 200-280 nm. Moreover, in the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention, it is preferable that the light irradiated by the UV-LED is radiation having a wavelength of 350 nm or more. In these configurations, the pressure-sensitive adhesive layer cures and contracts with a high-pressure mercury lamp, which is a light source containing radiation with a wavelength of 200 to 280 nm that is not included in external light or light emitted from a blue optical semiconductor element, thereby improving reworkability. On the other hand, curing shrinkage does not progress due to external light or radiation with a wavelength of 350 nm or more contained in light emitted from a blue optical semiconductor element, so that the adhesive layer (sealing It is preferable in that it can prevent peeling of the stopper material).

A second aspect of the present invention comprises a substrate, one or more optical semiconductor elements arranged on the substrate, and the photocurable adhesive sheet of the first aspect of the present invention, wherein the photocurable adhesive Provided is an optical semiconductor device, wherein a sheet seals the optical semiconductor element. The optical semiconductor device of the second aspect of the present invention is preferably a self-luminous display device. A third aspect of the present invention provides an image display device including the self-luminous display device.

The optical semiconductor device (preferably self-luminous display device) of the second aspect of the present invention and the image display device of the third aspect of the present invention use the photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention. Therefore, the curing shrinkage of the adhesive layer is less likely to proceed due to ultraviolet rays contained in the outside light or the light emitted from the blue optical semiconductor element in the usage environment, and the adhesive layer (sealing material) It is preferable in that peeling can be prevented. In addition, when a failure such as non-lighting of the optical semiconductor element occurs, the adhesive layer (sealing material) can be peeled off and repaired with good reworkability by irradiating the adhesive layer with a high-pressure mercury lamp. is preferred.

When the photocurable pressure-sensitive adhesive sheet of the present invention is used as a sealing material for a self-luminous display device, if a decrease in yield or a sealing error occurs, the pressure-sensitive adhesive layer after irradiation with a high-pressure mercury lamp will cure and shrink. , is preferable in that it can be peeled off with excellent reworkability and the display panel can be reused.

Further, in the self-luminous display device using the photocurable adhesive sheet of the present invention as a sealing material, the adhesive layer is damaged by ultraviolet light contained in external light in the usage environment or light emitted from the blue optical semiconductor element. It is suitable in that curing shrinkage can prevent the pressure-sensitive adhesive layer (sealing material) from peeling off from the display panel.

Furthermore, when a failure such as non-lighting of the optical semiconductor element occurs in the self-luminous display device, the adhesive layer is peeled off and removed with good reworkability by irradiating the adhesive layer with a high-pressure mercury lamp. It is also preferable in that it can be done.

FIG. 1 is a diagram (sectional view) schematically showing one embodiment of the photocurable pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a diagram (sectional view) schematically showing one embodiment of the photocurable pressure-sensitive adhesive sheet of the present invention. FIG. 3 is a schematic diagram (sectional view) showing an embodiment of the self-luminous display device (mini/micro LED display device) of the present invention. FIG. 4 is a schematic diagram (cross-sectional view) showing a process for carrying out one embodiment of rework of the self-luminous display device (mini/micro LED display device) of the present invention.

A first aspect of the present invention provides a photocurable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer that is cured by exposure to radiation. The pressure-sensitive adhesive layer has a 180° peeling force of 11 N/20 mm or less after irradiation with a high-pressure mercury lamp. The photocurable pressure-sensitive adhesive sheet of the first aspect of the present invention may be referred to as the "photocurable pressure-sensitive adhesive sheet of the present invention", and the "pressure-sensitive adhesive layer cured by irradiation with radiation" may be referred to as the "pressure-sensitive adhesive layer of the present invention". .

A second aspect of the present invention comprises a substrate, one or more optical semiconductor elements arranged on the substrate, and the photocurable adhesive sheet of the first aspect of the present invention, and Provided is an optical semiconductor device, wherein a flexible adhesive sheet seals the optical semiconductor element. The optical semiconductor device of the second aspect of the present invention is preferably a self-luminous display device. A third aspect of the present invention provides an image display device including the self-luminous display device. The optical semiconductor device and the self-luminous display device of the second aspect of the present invention are sometimes referred to as "the optical semiconductor device of the present invention" and "the self-luminous display device of the present invention", respectively. Also, the image display device according to the third aspect of the present invention may be referred to as "the image display device of the present invention".

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto and is merely an example.
1 and 2 are cross-sectional views showing one embodiment of the photocurable pressure-sensitive adhesive sheet of the present invention.

The photocurable pressure-sensitive adhesive sheet 10 according to one embodiment of the present invention in FIG. and a release film S2 bonded to the main surface of the .

The photocurable pressure-sensitive adhesive sheet 11 according to one embodiment of the present invention in FIG. and a release film S4 bonded to the main surface of the .

In FIGS. 1 and 2, the pressure-sensitive adhesive layer 1 has two main surfaces facing each other, and may be a single layer or a laminated structure of two or more layers.

FIG. 3 is a schematic diagram (sectional view) showing an embodiment of the self-luminous display device (mini/micro LED display device) of the present invention.

A self-luminous display device (mini/micro LED display device) 20 according to one embodiment of the present invention shown in FIG. of the photocurable adhesive sheet 11. The optical semiconductor element 4 on the substrate 2 is sealed with the adhesive layer 1 of the photocurable adhesive sheet 11 .
Each configuration will be described in detail below.

<Photocurable adhesive sheet, adhesive layer>
The photocurable pressure-sensitive adhesive sheet of the present invention is preferably used for encapsulating optical semiconductor elements of self-luminous display devices such as mini/micro LED display devices in which a plurality of optical semiconductor elements are arranged on a substrate. The optical semiconductor element is not particularly limited as long as it is a semiconductor element having a light emitting function, and includes a light emitting diode (LED), a semiconductor laser, and the like.

The form of the photocurable adhesive sheet of the present invention is not particularly limited as long as the adhesive surface is the adhesive surface of the adhesive layer of the present invention (adhesive layer surface). For example, it may be a single-sided PSA sheet having an adhesive surface on only one side, or a double-sided PSA sheet having an adhesive surface on both sides. Moreover, when the photocurable pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, the photocurable pressure-sensitive adhesive sheet of the present invention may have a form in which both pressure-sensitive adhesive surfaces are provided by the pressure-sensitive adhesive layer of the present invention. Alternatively, one adhesive surface is provided by the adhesive layer of the present invention, and the other adhesive surface is provided by an adhesive layer other than the adhesive layer of the present invention (another adhesive layer). may From the viewpoint of encapsulating the optical semiconductor element of the self-luminous display device, a single-sided pressure-sensitive adhesive sheet is preferable.

The photocurable pressure-sensitive adhesive sheet of the present invention may be a so-called "substrate-less type" pressure-sensitive adhesive sheet that does not have a substrate (substrate layer), or a type pressure-sensitive adhesive sheet that has a substrate. good. In this specification, a "base-less type" pressure-sensitive adhesive sheet may be referred to as a "base-less pressure-sensitive adhesive sheet", and a type pressure-sensitive adhesive sheet having a base may be referred to as a "base-attached pressure-sensitive adhesive sheet". be. Examples of the substrate-less pressure-sensitive adhesive sheet include a double-sided pressure-sensitive adhesive sheet consisting only of the pressure-sensitive adhesive layer of the present invention, or a pressure-sensitive adhesive layer of the present invention and other pressure-sensitive adhesive layers (a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer of the present invention). A double-sided pressure-sensitive adhesive sheet consisting of Examples of the PSA sheet with a substrate include a single-sided PSA sheet having the PSA layer of the present invention on one side of the substrate, a double-sided PSA sheet having the PSA layer of the present invention on both sides of the substrate, and , a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer of the present invention on one side of a substrate and another pressure-sensitive adhesive layer on the other side.

Among the above, from the viewpoint of improving optical properties such as transparency, a substrate-less pressure-sensitive adhesive sheet is preferable, and more preferably, a double-sided pressure-sensitive adhesive sheet having no substrate (substrate-less double-sided adhesive sheet). Further, when the photocurable pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet having a substrate, it is not particularly limited, but from the viewpoint of processability, a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer of the present invention on both sides of the substrate (base) A double-sided pressure-sensitive adhesive sheet with material) is preferred.
The above-mentioned "base material (base material layer)" means that when the pressure-sensitive adhesive layer of the present invention is used (attached) to an adherend (optical member, etc.), it is attached to the adherend together with the pressure-sensitive adhesive layer. It does not include the release film (separator) that is peeled off when using (sticking) the adhesive sheet.

In the self-luminous display device, there is a problem that non-lighting, different colors, chipping, misalignment, etc. of the optical semiconductor elements occur, resulting in a decrease in yield. Further, when the display panel is sealed, mistakes such as wrinkling, contamination by foreign matter, and air bubbles may occur. When such a yield reduction or sealing error occurs, so-called rework is performed in which the sealing material is peeled off from the display panel, removed, and reused.

The pressure-sensitive adhesive layer of the present invention has a 180° peeling force of 11 N/20 mm or less after irradiation with a high-pressure mercury lamp. In this configuration, when the photocurable adhesive sheet of the present invention is used as a sealing material for a self-luminous display device, if a decrease in yield or a sealing error occurs, the adhesive layer after irradiation with a high-pressure mercury lamp ( As a result of the curing shrinkage of the sealing material), the anchor effect between the substrate of the display panel and the optical semiconductor element is reduced, so that the sealing material can be easily peeled off and the sealing material is less likely to remain on the display panel after peeling. It is suitable in that the sealing material can be peeled off with excellent reworkability. Further, in the case where the self-luminous display device of the present invention has a failure such as non-lighting of the optical semiconductor element, the adhesive layer of the present invention can be peeled off and reworked with good reworkability by irradiating the adhesive layer of the present invention with a high-pressure mercury lamp. It is also preferable in that it can be removed and repaired.

From the viewpoint of further improving the reworkability of the photocurable pressure-sensitive adhesive sheet of the present invention, the 180° peeling force of the pressure-sensitive adhesive layer of the present invention after irradiation with a high-pressure mercury lamp is preferably 10.5 N/20 mm or less, and 10 N/20 mm or less. is more preferable, 9.8 N/20 mm or less is more preferable, and 9.5 N/20 mm or less may be used. In addition, the lower limit of the 180° peeling force of the pressure-sensitive adhesive layer of the present invention after irradiation with a high-pressure mercury lamp is not particularly limited, and the lower the better, that is, 0 N/20 mm is preferable, but 0.1 N/20 mm or more. may

The 180° peel strength of the pressure-sensitive adhesive layer of the invention after irradiation with a high-pressure mercury lamp can be measured by the method described in Examples below. , Mw, Tg, BP equivalent of BP polymer (A) described later; Weight fraction of BP polymer (A); Composition of monomer components constituting BP polymer (A) and ethylenically unsaturated compound (B), functional groups type and amount of; cross-linking agent type and amount) and the like.

In the pressure-sensitive adhesive layer of the present invention, the rate of change in 180° peel force before and after UV-LED irradiation (the percentage change when the 180° peel force before UV-LED irradiation is 100%) is within 10%. is preferred. In a self-luminous display device using the photocurable pressure-sensitive adhesive sheet of the present invention as a sealing material, this structure causes the pressure-sensitive adhesive sheet to be exposed to UV rays contained in external light in the usage environment or light emitted from blue optical semiconductor elements. This is preferable in that it can prevent the adhesive layer (sealing material) from peeling off from the display panel due to curing shrinkage of the layer. From the viewpoint of preventing peeling of the sealing material of the self-luminous display device in the usage environment, the rate of change is preferably within 9%, more preferably within 8%, and more preferably within 7%, It may be within 6% or within 5%. The lower limit of the change rate of the peel force is not particularly limited, and the lower the better, that is, 0% is preferable, but it may be 0.01% or more.

The 180° peeling force of the adhesive layer of the present invention before irradiation is not particularly limited, but from the viewpoint of adhesion reliability to the display panel, it preferably exceeds 11 N / 20 mm, more preferably 11.5 N / 20 mm or more. Preferably, it may be 12 N/20 mm or more. In addition, the upper limit of the 180° peeling force before irradiation of the present invention is not particularly limited, and the higher the better, but it may be, for example, 100 N/20 mm or less.

The pressure-sensitive adhesive layer of the present invention preferably has a 180° peel strength of more than 11 N/20 mm after UV-LED irradiation. In a self-luminous display device using the photocurable pressure-sensitive adhesive sheet of the present invention as a sealing material, this structure causes the pressure-sensitive adhesive sheet to be exposed to UV rays contained in external light in the usage environment or light emitted from blue optical semiconductor elements. This is preferable in that it can prevent the adhesive layer (sealing material) from peeling off from the display panel due to curing shrinkage of the layer. From the viewpoint of preventing peeling of the sealing material of the self-luminous display device in the usage environment, the 180 ° peeling force after UV-LED irradiation is more preferably 11.5 N / 20 mm or more, even if it is 12 N / 20 mm or more. good. Further, the upper limit of the 180° peeling force after UV-LED irradiation of the present invention is not particularly limited, and the higher the better, but it may be 100 N/20 mm or less.

The 180° peeling force of the pressure-sensitive adhesive layer of the present invention before radiation irradiation or before and after UV-LED irradiation, and the rate of change thereof can be measured by Examples described later, and the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer of the present invention (e.g., Mw, Tg, BP equivalent of BP polymer (A) described later; weight fraction of BP polymer (A); BP polymer (A) and monomers constituting ethylenically unsaturated compound (B) It can be adjusted by the composition of the components, the type and amount of the functional group; the type and amount of the cross-linking agent), and the like.

The pressure-sensitive adhesive layer of the present invention preferably has a tensile storage modulus (E'a25) at 25°C after irradiation with a high-pressure mercury lamp of 400 kPa or more. In this configuration, when the photocurable pressure-sensitive adhesive sheet of the present invention is used as a sealing material for an optical semiconductor element of a self-luminous display device, if a decrease in yield or a sealing error occurs, This is preferable in that the reworkability of the pressure-sensitive adhesive layer (sealing material) is improved. From the viewpoint of further improving the reworkability of the pressure-sensitive adhesive layer of the present invention, E'a25 is more preferably 500 kPa or more, still more preferably 600 kPa or more. The upper limit of E'a25 is not particularly limited, and the higher the better, but it may be 10000 kPa or less.

The pressure-sensitive adhesive layer of the present invention preferably has a tensile storage modulus (E'a85) at 85°C after irradiation with a high-pressure mercury lamp of 500 kPa or more. In this configuration, when the photocurable pressure-sensitive adhesive sheet of the present invention is used as a sealing material for an optical semiconductor element of a self-luminous display device, if a decrease in yield or a sealing error occurs, This is preferable in that the reworkability of the pressure-sensitive adhesive layer (sealing material) is improved. From the viewpoint of further improving the reworkability of the pressure-sensitive adhesive layer of the present invention, E'a85 is more preferably 520 kPa or more, still more preferably 550 kPa or more, and may be 570 kPa or more. The upper limit of E'a85 is not particularly limited, and the higher the better, but it may be 10000 kPa or less.

The pressure-sensitive adhesive layer of the present invention preferably has a shear storage modulus (G'a25) at 25°C after UV-LED irradiation of 500 kPa or less. In a self-luminous display device using the photocurable pressure-sensitive adhesive sheet of the present invention as a sealing material, this structure causes the pressure-sensitive adhesive sheet to be exposed to UV rays contained in external light in the usage environment or light emitted from blue optical semiconductor elements. This is preferable in that it can prevent the adhesive layer (sealing material) from peeling off from the display panel due to curing shrinkage of the layer. G'a25 is more preferably 300 kPa or less, still more preferably 200 kPa or less, and may be 180 kPa or less from the viewpoint of preventing peeling of the sealing material of the self-luminous display device in the usage environment. Also, the lower limit of G'a25 is not particularly limited, but may be 10 kPa or more.

The pressure-sensitive adhesive layer of the present invention preferably has a shear storage modulus (G'a85) at 85°C after UV-LED irradiation of 95 kPa or less. In a self-luminous display device using the photocurable pressure-sensitive adhesive sheet of the present invention as a sealing material, this structure causes the pressure-sensitive adhesive sheet to be exposed to UV rays contained in external light in the usage environment or light emitted from blue optical semiconductor elements. This is preferable in that it can prevent the adhesive layer (sealing material) from peeling off from the display panel due to curing shrinkage of the layer. G'a85 is more preferably 90 kPa or less, still more preferably 85 kPa or less, and may be 80 kPa or less from the viewpoint of preventing peeling of the sealing material of the self-luminous display device in the usage environment. Also, G'a85 is not particularly limited, but may be 10 kPa or more.

The pressure-sensitive adhesive layer of the present invention preferably has a shear storage modulus (G'b25) at 25°C before irradiation with radiation of 500 kPa or less. This configuration is suitable for a self-luminous display device using the photocurable pressure-sensitive adhesive sheet of the present invention as an encapsulating material, in terms of being excellent in followability to optical semiconductor elements. G'b25 is more preferably 300 kPa or less, still more preferably 200 kPa or less, and may be 160 kPa or less, from the viewpoint of being able to further improve step conformability. G'b25 is not particularly limited, but from the viewpoint of adhesion reliability, it is preferably 50 kPa or more, and may be 100 kPa or more.

The pressure-sensitive adhesive layer of the present invention preferably has a shear storage modulus (G'b85) at 85°C before irradiation with radiation of 95 kPa or less. This configuration is suitable for a self-luminous display device using the photocurable pressure-sensitive adhesive sheet of the present invention as an encapsulating material, in terms of being excellent in followability to optical semiconductor elements. From the viewpoint of being able to further improve step conformability, it is more preferably 90 kPa or less, still more preferably 85 kPa or less, and may be 80 kPa or less. Also, G'b85 is not particularly limited, but may be 50 kPa or more from the viewpoint of adhesion reliability.

The pressure-sensitive adhesive layer preferably has a ratio (kPa/μm) of a tensile storage modulus (E′a25:kPa) at 25° C. after irradiation with a high-pressure mercury lamp to a thickness (μm) of 1 or more. In this configuration, when the photocurable pressure-sensitive adhesive sheet of the present invention is used as a sealing material for an optical semiconductor element of a self-luminous display device, if a decrease in yield or a sealing error occurs, This is preferable in that the reworkability of the pressure-sensitive adhesive layer (sealing material) is improved. From the viewpoint of further improving the reworkability of the pressure-sensitive adhesive layer of the present invention, E'a25/thickness is preferably 5 or more, and may be 10 or more. E'a25/thickness is not particularly limited, but may be 50 or less.

The pressure-sensitive adhesive layer preferably has a ratio (kPa/μm) of a tensile storage modulus (E′a85:kPa) at 85° C. after irradiation with a high-pressure mercury lamp to a thickness (μm) of 1 or more. In this configuration, when the photocurable pressure-sensitive adhesive sheet of the present invention is used as a sealing material for an optical semiconductor element of a self-luminous display device, if a decrease in yield or a sealing error occurs, This is preferable in that the reworkability of the pressure-sensitive adhesive layer (sealing material) is improved. From the viewpoint of further improving the reworkability of the pressure-sensitive adhesive layer of the present invention, E'a85/thickness is preferably 5 or more, and may be 10 or more. E'a85/thickness is not particularly limited, but may be 50 or less.

Tensile storage modulus (E'a25; E'a85) at 25° C. or 85° C. after high-pressure mercury lamp irradiation, shear storage modulus at 25° C. or 85° C. after UV-LED irradiation in the pressure-sensitive adhesive layer of the present invention (G'a25; G'a85) and the storage elastic modulus (G'b25; G'b85) at 25° C. or 85° C. before irradiation can be measured by Examples described later, and the pressure-sensitive adhesive layer of the present invention The composition of the monomers of the pressure-sensitive adhesive composition that constitute It can be adjusted by the composition of the monomer component constituting (B), the type and amount of the functional group; the type and amount of the cross-linking agent), and the like.

In the photocurable pressure-sensitive adhesive sheet of the present invention, the light irradiated by the high-pressure mercury lamp preferably contains radiation with a wavelength of 200 to 280 nm, and the light irradiated by the UV-LED is radiation with a wavelength of 350 nm or more. is preferably In these configurations, the pressure-sensitive adhesive layer of the present invention cures and contracts with a high-pressure mercury lamp, which is a light source containing radiation with a wavelength of 200 to 280 nm, which is not included in external light or light emitted from a blue optical semiconductor element, resulting in reworkability. While the is improved, the curing shrinkage does not progress due to the radiation having a wavelength of 350 nm or more contained in the light emitted from the external light or the blue optical semiconductor element, so that the pressure-sensitive adhesive layer It is preferable in that peeling of the (sealing material) can be prevented.

The maximum transmittance of the pressure-sensitive adhesive layer of the present invention at a wavelength of 200 to 400 nm is preferably 5% or more. This configuration is preferable in that the pressure-sensitive adhesive layer can be cured and shrunk by irradiation with the high-pressure mercury lamp, thereby improving reworkability. The maximum transmittance of the adhesive layer at a wavelength of 200 to 400 nm is preferably 10% or more, more preferably 15% or more, and may be 20% or more or 25% or more in terms of improving reworkability. .

The “maximum transmittance in the wavelength range of 200 to 400 nm” means the highest transmittance in the wavelength range of 200 to 400 nm. For example, when there is one maximum value of transmittance in the wavelength region of 200 to 400 nm, the maximum value becomes the maximum value of transmittance. If there is no maximum transmittance in the wavelength range of 200 to 400 nm, the maximum transmittance is the transmittance of the wavelength of 200 nm or 400 nm, whichever is higher. The same applies to the "maximum value of transmittance at a wavelength of 400 to 700 nm".

The maximum transmittance of the pressure-sensitive adhesive layer of the present invention at a wavelength of 200 to 400 nm is determined by the composition of the monomers of the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer of the present invention (for example, Mw, Tg of the BP polymer (A) described below , BP equivalent; weight fraction of BP polymer (A); composition of monomer components constituting BP polymer (A) and ethylenically unsaturated compound (B), type and amount of functional group; type and amount of cross-linking agent) , can be adjusted by the type and amount of the coloring agent to be described later.

The thickness of the adhesive layer of the present invention is, for example, about 10 to 500 μm, and may be 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. The thickness of the adhesive layer of the present invention may be 400 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. By setting the thickness to 10 μm or more, the pressure-sensitive adhesive layer can easily follow the step portion, thereby improving the step absorbability. Further, by setting the thickness to 500 μm or less, the reworkability of the pressure-sensitive adhesive layer of the present invention is improved.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the present invention is not particularly limited as long as it can achieve the desired properties described above, but preferably contains a polymer (A) having a benzophenone structure in its side chain. A containing form is preferred. The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the present invention contains a mixture of monomer components constituting the polymer (A) having a benzophenone structure in its side chains or the polymer (A) having a benzophenone structure in its side chains. A form containing a partially polymerized mixture of constituent monomer components is also preferred. Although this embodiment will be described below, the present invention is not limited to this embodiment. The adhesive layer of the present embodiment is "adhesive layer (A)", the adhesive composition is "adhesive composition (A)", and the polymer having a benzophenone structure in the side chain contained in the adhesive composition (A). (A) may be referred to as "BP polymer (A)".

As used herein, the term "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of an acrylic monomer. The acrylic monomer refers to a monomer derived from a monomer having at least one (meth)acryloyl group in one molecule. Moreover, in this specification, "(meth)acryloyl" is meant to comprehensively refer to acryloyl and methacryloyl. Similarly, "(meth)acrylate" is a generic term for acrylate and methacrylate, and "(meth)acrylic" is generic for acrylic and methacrylic.

As used herein, the term "ethylenically unsaturated compound" refers to a compound having at least one ethylenically unsaturated group in the molecule. Examples of ethylenically unsaturated groups include (meth)acryloyl groups, vinyl groups, allyl groups, and the like. Hereinafter, a compound having one ethylenically unsaturated group may be referred to as a "monofunctional monomer", and a compound having two or more ethylenically unsaturated groups may be referred to as a "polyfunctional monomer". Moreover, among polyfunctional monomers, a compound having X ethylenically unsaturated groups may be expressed as an "X-functional monomer".

In the present specification, that the pressure-sensitive adhesive composition contains an ethylenically unsaturated compound means including the above-mentioned ethylenically unsaturated compound in the form of a partially polymerized product unless otherwise specified. Such a partially polymerized product is usually composed of the ethylenically unsaturated compound (unreacted monomer) in which the ethylenically unsaturated group is unreacted and the ethylenically unsaturated compound in which the ethylenically unsaturated group is polymerized. It is a mixture containing

In this specification, the total monomer components constituting the pressure-sensitive adhesive composition refer to the monomer components constituting the polymer contained in the pressure-sensitive adhesive composition and the monomers contained in the pressure-sensitive adhesive composition in the form of unreacted monomers. Refers to the total amount of ingredients. The composition of the monomer components constituting the pressure-sensitive adhesive composition generally matches the composition of the monomer components of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and the composition of the monomer components constituting the photocured product thereof.

As used herein, the term "active energy ray" is a concept that includes light such as ultraviolet rays, visible rays, and infrared rays, and radiation such as α rays, β rays, γ rays, electron beams, neutron rays, and X rays. be.

[Adhesive composition (A)]
The pressure-sensitive adhesive composition (A) contains a polymer (A) having a benzophenone structure on its side chain. In addition, the pressure-sensitive adhesive composition (A) is a mixture of monomer components constituting the polymer (A) having a benzophenone structure in a side chain or a part of a mixture of monomer components constituting the polymer (A) having a benzophenone structure in a side chain. It may be in a form containing a polymer. The pressure-sensitive adhesive composition (A) may further contain an ethylenically unsaturated compound (B). In addition to the above, the adhesive composition (A) may contain a photopolymerization initiator (C) that absorbs ultraviolet rays with a wavelength of 300 nm to 500 nm to generate radicals and other additives.
In addition, in this specification, the above-mentioned "mixture of monomer components" includes the case of being composed of a single monomer component and the case of being composed of two or more kinds of monomer components. In addition, the above-mentioned "partially polymerized mixture of monomer components" means a composition in which one or more of the constituent monomer components of the above-mentioned "mixture of monomer components" is partially polymerized. do.

The adhesive composition (A) may have any form, for example, solvent type, emulsion type, hot melt type (hot melt type), non-solvent type (active energy ray curable type, e.g. monomer mixtures, or monomer mixtures and partial polymers thereof, etc.). The pressure-sensitive adhesive composition (A) is preferably active energy ray-curable from the viewpoint of obtaining a pressure-sensitive adhesive layer with excellent appearance. In this specification, the pressure-sensitive adhesive composition means a composition used for forming the pressure-sensitive adhesive layer, and includes the meaning of the composition used for forming the pressure-sensitive adhesive.

The pressure-sensitive adhesive composition (A) is not particularly limited, but for example, a composition containing the BP polymer (A) as an essential component; and the like. Although not particularly limited, the former includes, for example, so-called solvent-based adhesive compositions and water-dispersed adhesive compositions (emulsion-type adhesive compositions), and the latter includes, for example, so-called active energy ray curing. type adhesive composition and the like.

The pressure-sensitive adhesive composition (A) may be solvent-based, as described above. The solvent is not particularly limited as long as it is an organic compound used as a solvent. Examples include hydrocarbon solvents such as cyclohexane, hexane, and heptane; aromatic solvents such as toluene and xylene; ester solvents; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, butanol and isopropyl alcohol. In addition, the mixed solvent containing 2 or more types of solvents may be sufficient as the said solvent.

[Polymer (A) having a benzophenone structure in a side chain]
As a base polymer constituting the pressure-sensitive adhesive composition (A) of the present invention, a polymer (A) having a benzophenone structure in a side chain (BP polymer (A)) is included. That is, the pressure-sensitive adhesive composition (A) of the present invention is a pressure-sensitive adhesive composition containing the BP polymer (A) as a base polymer. In addition, BP polymer (A) can be used individually or in combination of 2 or more types.

The monomer component that can constitute the BP polymer (A) includes a compound having an ethylenically unsaturated group and a benzophenone structure in the molecule (hereinafter sometimes referred to as "ethylenically unsaturated BP"), and further , ethylenically unsaturated compounds other than ethylenically unsaturated BPs (hereinafter also referred to as "other ethylenically unsaturated compounds").

Preferred examples of the BP polymer (A) include acrylic polymers having benzophenone structures in side chains. The BP polymer (A) is preferably a polymer containing substantially no ethylenically unsaturated groups.

As used herein, the term "benzophenone structure" refers to a diallyl ketone structure represented by the general formula: Ar ¹ -(C=O)-Ar ² -; or -Ar ³ -(C=O)-Ar ² -; Say. Here, Ar ¹ in the above general formula is selected from phenyl groups which may have a substituent. Ar ² and Ar ³ in the above general formula are each independently selected from phenylene groups which may have a substituent. Ar ² and Ar ³ may be the same or different. The benzophenone structure can be excited by ultraviolet irradiation and in its excited state can abstract hydrogen radicals from other molecules or other parts of the molecule.

The adhesive layer (A) formed from the cured adhesive composition (A) containing the BP polymer (A) may contain a benzophenone structure. The benzophenone structure can cure the pressure-sensitive adhesive layer (A) by forming a crosslinked structure utilizing the abstraction reaction of hydrogen radicals when excited by ultraviolet irradiation.

As the BP polymer (A), Ar ¹ in the general ^formula : Ar ¹ —(C═O)—Ar ² —; A polymer having a benzophenone structure, which is an optional phenylene group, in a side chain is preferred. When at least one of Ar ¹ and Ar ² has one or more substituents, the substituents are each independently an alkoxy group (eg, an alkoxy group having 1 to 3 carbon atoms, preferably a methoxy group), It may be selected from the group consisting of halogen atoms (eg F, Cl, Br, etc., preferably Cl or Br), hydroxyl groups, amino groups and carboxyl groups.

The BP polymer (A) may have a side chain in which the above-described benzophenone structure is directly bonded to the main chain, for example, via one or more of an ester bond, an oxyalkylene structure, etc. It may also have side chains attached to the main chain. Preferred examples of the BP polymer (A) include polymers containing repeating units derived from ethylenically unsaturated BP. The repeating unit can be a polymerized residue reacted with the ethylenically unsaturated group of the corresponding ethylenically unsaturated BP.

Examples of the ethylenically unsaturated BP include 4-acryloyloxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone. optionally substituted acryloyloxybenzophenone such as , 2-hydroxy-4-acryloyloxybenzophenone; 4-[(2-acryloyloxy)ethoxy]benzophenone, 4-[(2-acryloyloxy)ethoxy] Acryloyloxyalkoxybenzophenones optionally having substituents such as -4'-bromobenzophenone; 4-methacryloyloxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone , 4-methacryloyloxyethoxy-4'-bromobenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone, optionally substituted methacryloyloxybenzophenone; 4-[(2-methacryloyloxy)ethoxy]benzophenone , 4-[(2-methacryloyloxy)ethoxy]-4'-methoxybenzophenone, optionally substituted methacryloyloxyalkoxybenzophenone; 4-vinylbenzophenone, 4'-bromo-3-vinylbenzophenone, 2-Hydroxy 4-methoxy-4′-vinylbenzophenone and other vinylbenzophenones that may have a substituent include, but are not limited to, these. Ethylenically unsaturated BPs can be used singly or in combination of two or more to prepare the BP polymer (A). Ethylenically unsaturated BP can be commercially available or can be synthesized by a known method. From the viewpoint of reactivity and the like, an ethylenically unsaturated BP having a (meth)acryloyl group, that is, an ethylenically unsaturated BP that is an acrylic monomer can be preferably employed.

The BP polymer (A) has a repeating unit derived from an ethylenically unsaturated BP and a repeating unit derived from an ethylenically unsaturated compound (another ethylenically unsaturated compound) that does not fall under the ethylenically unsaturated BP. It may be a copolymer. Such a BP polymer (A) may be a copolymer of monomer components containing the ethylenically unsaturated BP and the other ethylenically unsaturated compound. The BP polymer may also be a copolymer obtained by copolymerizing the ethylenically unsaturated BP with the partially polymerized product (prepolymer) of the monomer mixture consisting only of the other ethylenically unsaturated compound. One or two or more acrylic monomers can be preferably employed as the other ethylenically unsaturated compounds. A preferred example of the BP polymer (A) is an acrylic BP polymer in which more than 50% by weight (preferably more than 70% by weight, for example more than 90% by weight) of the monomer components constituting the BP polymer (A) is an acrylic monomer. is mentioned.

The monomer component constituting the BP polymer (A) may contain, as the other ethylenically unsaturated compound, one or more selected from (meth)acrylic acid alkyl esters having an alkyl group at the ester end. Hereinafter, a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having a carbon atom number of X or more and Y or less at the ester end may be referred to as "(meth)acrylic acid C _XY alkyl ester". . The monomer component constituting the BP polymer (A) preferably contains at least a (meth)acrylic acid C _1-20 alkyl ester as the other monomer, and preferably contains a (meth)acrylic acid C _4-20 alkyl ester. is more preferred, and it is even more preferred to contain a (meth)acrylic acid C _4-18 alkyl ester (eg, an acrylic acid C _4-9 alkyl ester).

Specific non-limiting examples of (meth)acrylic acid C _1-20 alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, ( meth) n-butyl acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) hexyl acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, (meth) ) Decyl acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, (meth) hexadecyl acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate and the like. Particularly preferred (meth)acrylic acid alkyl esters include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), isononyl acrylate and the like. Other specific examples of (meth)acrylic acid alkyl esters that can be preferably used include n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA), and the like. (Meth)acrylic acid alkyl esters may be used alone or in combination of two or more. The monomer component constituting the BP polymer (A) may contain, as the other ethylenically unsaturated compound, one or more selected from copolymerizable monomers described below.

The pressure-sensitive adhesive composition (A) is a photocurable acrylic pressure-sensitive adhesive composition in which more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of the total constituent monomer components are acrylic monomers. could be. A photocurable acrylic pressure-sensitive adhesive composition forms an acrylic photocured product by photocuring.

The weight average molecular weight (Mw) of the BP polymer (A) is not particularly limited, and can be, for example, about 0.5×10 ⁴ to 500×10 ⁴ . From the viewpoint of the cohesiveness of the pressure-sensitive adhesive layer (A) and the handleability of the photocurable pressure-sensitive adhesive sheet of the present invention, the Mw of the BP polymer (A) is usually 1×10 ⁴ or more. It is preferably 5×10 ⁴ or more, may be 10×10 ⁴ or more, may be 15×10 ⁴ or more, or may be 20×10 ⁴ or more. Also, from the viewpoint of reworkability of the pressure-sensitive adhesive layer (A), the Mw of the BP polymer (A) is usually 200×10 ⁴ or less, preferably 150×10 ⁴ or less. It may be 100×10 ⁴ or less, 70×10 ⁴ or less, or 50×10 ⁴ or less.
The weight-average molecular weight (Mw) of the polymer refers to a value converted to standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, model name "HLC-8320GPC" (column: TSKgelGMH-H(S), manufactured by Tosoh Corporation) can be used.

The glass transition temperature (Tg) of the BP polymer (A) is not particularly limited. The Tg of the BP polymer (A) may be, for example, -80°C or higher and 150°C or lower, -80°C or higher and 50°C or lower, or -80°C or higher and 10°C or lower. From the viewpoint of step absorbability of the pressure-sensitive adhesive layer (A), the Tg of the BP polymer (A) is suitably less than 0°C, preferably -10°C or less, and may be -20°C or less. , −30° C. or lower, −40° C. or lower, or −50° C. or lower. From the viewpoint of cohesiveness of the pressure-sensitive adhesive layer (A) and improvement of reworkability after photocuring, the Tg of the BP polymer (A) is usually -75°C or higher, and -70°C or higher. It's okay. In some embodiments, the Tg of BP polymer (A) may be -55°C or higher, or -45°C or higher. The Tg of the BP polymer (A) can be adjusted by the types and amounts of the monomer components that constitute the BP polymer.

Here, the glass transition temperature (Tg) of a polymer refers to the glass transition temperature determined by the Fox formula based on the composition of the monomer components constituting the polymer. The Fox equation is a relational expression between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
1/Tg=Σ(Wi/Tgi)
In the above Fox formula, Tg is the glass transition temperature of the copolymer (unit: K), Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on weight), and Tgi is the content of the monomer i. It represents the glass transition temperature (unit: K) of a homopolymer.

As the glass transition temperature of the homopolymer used for calculating the Tg, the value described in the known materials shall be used. For example, for the monomers listed below, the following values are used as the glass transition temperatures of the homopolymers of the monomers.
2-ethylhexyl acrylate: -70°C
n-butyl acrylate: -55°C
Isostearyl acrylate: -18°C
Methyl methacrylate: 105°C
Methyl acrylate: 8°C
Cyclohexyl acrylate: 15°C
N-vinyl-2-pyrrolidone: 54°C
2-Hydroxyethyl acrylate: -15°C
4-hydroxybutyl acrylate: -40°C
Isobornyl acrylate: 94°C
Acrylic acid: 106°C
Methacrylic acid: 228°C

For the glass transition temperatures of homopolymers of monomers other than those exemplified above, the values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. When multiple types of values are described in this document, the highest value is adopted. For monomers for which the glass transition temperature of homopolymers is not described in the above Polymer Handbook, the value obtained by the measurement method described in JP-A-2007-51271 shall be used. For polymers for which the manufacturer or the like provides a nominal value for the glass transition temperature, the nominal value may be adopted.

The BP polymer (A) preferably contains, for example, about 0.5 mg or more of a benzophenone structure in terms of 4-benzoylphenyl acrylate per 1 g of the polymer. Hereinafter, the value obtained by converting the number of benzophenone structures contained in 1 g of BP polymer into the amount in terms of 4-benzoylphenyl acrylate is sometimes referred to as the BP equivalent of the BP polymer (unit: mg/g). For example, containing 40 μmol of benzophenone structures per gram, the BP equivalent weight of the polymer is calculated as 10 mg/g.

From the viewpoint of obtaining a higher photocuring effect (for example, an effect of improving workability by photocuring), in some embodiments, the BP equivalent of the BP polymer (A) is usually 0.1 mg/g or more. 0.5 mg/g or more, 1 mg/g or more, 5 mg/g or more, 8 mg/g or more, 10 mg/g or more, 15 mg/g or more, 20 mg/g or more. g or more. In some embodiments, the BP equivalent of the BP polymer (A) is usually 100 mg/g or less from the viewpoint of enhancing the impact resistance and peel strength of the joints formed by photocuring. It may be 80 mg/g or less, 60 mg/g or less, 40 mg/g or less, 25 mg/g or less, or 15 mg/g or less. The BP equivalent of the BP polymer (A) can be adjusted by the composition of the monomer components constituting the BP polymer (A).

In addition, the BP equivalent is preferably 50 mg/g or more, and may be 100 mg/g or more, from the viewpoint of reducing the release force by photocuring and performing reworkability and repair.

The weight ratio of the BP polymer (A) in the entire pressure-sensitive adhesive composition (A), that is, the weight fraction of the BP polymer in the pressure-sensitive adhesive composition (A) is not particularly limited, and the steps of the pressure-sensitive adhesive layer (A) The absorbability and the reworkability of the photocured product can be suitably balanced. In some embodiments, the weight fraction of the BP polymer (A) may be, for example, 2 wt% or more, typically 4 wt% or more, may be 10 wt% or more, 15 wt% or more. % by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, or 55% by weight or more. Reworkability tends to improve as the weight fraction of the BP polymer (A) increases.
A mode in which the weight fraction of the BP polymer (A) in the pressure-sensitive adhesive composition (A) is substantially 100% by weight (for example, 99.5% by weight or more) can also be implemented. Also, from the viewpoint of ease of adhesive performance, in some embodiments, the weight fraction of the BP polymer (A) in the adhesive composition (A) may be, for example, less than 99% by weight, and less than 95% by weight. may be less than 85 wt%, less than 70 wt%, less than 50 wt%, or less than 40 wt%.

It is preferable that 1 g of the pressure-sensitive adhesive composition (A) contain, for example, about 0.1 mg or more of the benzophenone structure in terms of 4-benzoylphenyl acrylate. Hereinafter, the weight of the benzophenone structure contained per 1 g of the pressure-sensitive adhesive composition (A) converted to 4-benzoylphenyl acrylate is sometimes referred to as the BP equivalent (unit: mg/g) of the pressure-sensitive adhesive composition. From the viewpoint of obtaining a higher photocuring effect (for example, an effect of improving reworkability by photocuring), in some embodiments, the BP equivalent of the pressure-sensitive adhesive composition is usually 0.3 mg/g or more. and may be 0.5 mg/g or more, 1 mg/g or more, 5 mg/g or more, 10 mg/g or more, or 20 mg/g or more. In some embodiments, the BP equivalent of the pressure-sensitive adhesive composition is usually 100 mg/g or less from the viewpoint of the impact resistance of the joint due to the photocured product and the suppression of distortion in the photocured product. and may be 80 mg/g or less, 60 mg/g or less, 40 mg/g or less, 25 mg/g or less, or 15 mg/g or less.

[Ethylenically unsaturated compound (B)]
The pressure-sensitive adhesive composition (A) may contain an ethylenically unsaturated compound (B) in addition to the BP polymer (A). When the pressure-sensitive adhesive composition (A) is a solvent-free (active energy ray-curable) pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition (A) contains an ethylenically unsaturated compound (B). is preferred. On the other hand, when the pressure-sensitive adhesive composition (A) is a solvent-type or emulsion-type pressure-sensitive adhesive composition, the ethylenically unsaturated compound (B) may not be contained.

Further, when the pressure-sensitive adhesive composition (A) contains a mixture of monomer components constituting the BP polymer (A) or a partial polymer of a mixture of monomer components constituting the BP polymer (A), the monomer component Since it may contain other ethylenically unsaturated compounds as described above, it does not necessarily contain an ethylenically unsaturated compound (B). When the pressure-sensitive adhesive composition (A) containing the mixture of the monomer components or a partial polymer thereof contains the ethylenically unsaturated compound (B), the ethylenically unsaturated compound (B) is the other ethylenically unsaturated compound. It may be the same as or different from the saturated compound.

Examples of compounds that can be used as the ethylenically unsaturated compound (B) include the (meth)acrylic acid alkyl esters described above and the ethylenically unsaturated BPs described above. Of these, at least (meth)acrylic acid alkyl esters (e.g., (meth)acrylic acid C _1-20 alkyl esters, more preferably (meth)acrylic acid C _4-18 alkyl esters, still more preferably acrylic acid C _4-9 Alkyl esters) are preferably used. Particularly preferred (meth)acrylic acid alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). Other specific examples of (meth)acrylic acid alkyl esters that can be preferably used include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA), and the like. mentioned. (Meth)acrylic acid alkyl esters may be used alone or in combination of two or more. In some embodiments, the ethylenically unsaturated compound (B) preferably comprises either or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA), and contains at least BA. It is more preferable to include

The ethylenically unsaturated compound (B) may contain 40% by weight or more of the C _4-9 alkyl acrylate. The proportion of the C _4-9 alkyl acrylate in the monomer component may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more. In addition, from the viewpoint of enhancing the cohesiveness of the pressure-sensitive adhesive layer (A), the proportion of the C _4-9 alkyl acrylate in the ethylenically unsaturated compound (B) is usually 99.5% by weight or less. Suitable, it may be 95 wt% or less, 85 wt% or less, 70 wt% or less, or 60 wt% or less.

Other examples of compounds that can be used as the ethylenically unsaturated compound (B) include ethylenically unsaturated compounds (copolymerizable monomers) that can be copolymerized with (meth)acrylic acid alkyl esters. As a copolymerizable monomer, a monomer having a polar group (for example, a carboxy group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be preferably used. A monomer having a polar group can serve, for example, to introduce a cross-linking point into a polymer containing repeating units derived from the monomer, or to increase the cohesion of the pressure-sensitive adhesive layer (A). The copolymerizable monomers can be used singly or in combination of two or more.

Specific non-limiting examples of copolymerizable monomers include the following.
Carboxy group-containing monomers: for example acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.
Acid anhydride group-containing monomers: for example maleic anhydride, itaconic anhydride.
Hydroxyl group-containing monomers: for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (meth)acrylic 4-hydroxybutyl acid, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxy hydroxyalkyl (meth)acrylates such as methylcyclohexyl)methyl (meth)acrylate;
Monomers containing sulfonic or phosphoric acid groups: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfo propyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloyl phosphate and the like.
Epoxy group-containing monomers: For example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethylglycidyl (meth)acrylate, allyl glycidyl ether, glycidyl ether (meth)acrylate, and the like.
Cyano group-containing monomers: for example acrylonitrile, methacrylonitrile and the like.
Isocyanate group-containing monomers: for example, 2-(meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate and the like.
Amido group-containing monomers: for example, (meth)acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth) N,N-dialkyl(meth)acrylamides such as acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide; N-ethyl(meth)acrylamide , N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-alkyl (meth)acrylamide such as Nn-butyl (meth)acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, such as N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth) N-hydroxyalkyl (meth)acrylamides such as acrylamide; monomers having an alkoxy group and an amide group, such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide N-alkoxyalkyl(meth)acrylamides such as N-(meth)acrylamide; N,N-dimethylaminopropyl(meth)acrylamide, N-(meth)acryloylmorpholine and the like.
Amino group-containing monomers: for example aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate. Monomers with epoxy groups: eg glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allyl glycidyl ether.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N- Vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3 -morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinyl thiazole, N-vinylisothiazole, N-vinylpyridazine and the like (for example, lactams such as N-vinyl-2-caprolactam);
Monomers having a succinimide skeleton: for example, N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyhexamethylenesuccinimide and the like.
Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.
Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl itaconimide and the like.
Aminoalkyl (meth)acrylates: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, t (meth)acrylate - butylaminoethyl.
Alkoxy group-containing monomers: for example, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, (meth)acrylic acid Alkoxyalkyl (meth)acrylates (alkoxyalkyl (meth)acrylates) such as butoxyethyl and ethoxypropyl (meth)acrylate; methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, (meth)acrylate alkoxyalkylene glycol (meth)acrylates (for example, alkoxypolyalkylene glycol (meth)acrylates) such as methoxypolypropylene glycol acrylate;
Alkoxysilyl group-containing monomers: such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxy alkoxysilyl group-containing (meth)acrylates such as propylmethyldiethoxysilane; alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane;
Vinyl esters: For example, vinyl acetate, vinyl propionate and the like.
Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Aromatic vinyl compounds: for example, styrene, α-methylstyrene, vinyltoluene and the like.
Olefins: For example, ethylene, butadiene, isoprene, isobutylene and the like.
(Meth)acrylic acid esters having an alicyclic hydrocarbon group: for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, etc. alicyclic hydrocarbon group-containing (meth)acrylate.
(Meth)acrylic acid esters having an aromatic hydrocarbon group: For example, aromatic hydrocarbon group-containing (meth)acrylates such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate and benzyl (meth)acrylate.
In addition, heterocycle-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen atom-containing (meth)acrylates such as vinyl chloride and fluorine atom-containing (meth)acrylates, silicon atom-containing such as silicone (meth)acrylates (meth)acrylates, (meth)acrylic acid esters obtained from terpene compound derivative alcohols, and the like.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to use 0.01% by weight or more of the total monomer components constituting the pressure-sensitive adhesive composition (A). be. From the viewpoint of better exhibiting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer used (that is, the weight fraction of the copolymerizable monomer in the entire monomer component) is 0.1% by weight of the total monomer component. or more, or 0.5% by weight or more. From the viewpoint of facilitating the balance of adhesive properties, the amount of the copolymerizable monomer to be used is generally 50% by weight or less, preferably 40% by weight or less, of the total monomer components.

で表わされるＮ－ビニル環状アミドを用いることができる。ここで、一般式（１）中、Ｒ¹は２価の有機基であり、具体的には－（ＣＨ₂）_n－である。ｎは２～７（好ましくは２，３または４）の整数である。なかでも、Ｎ－ビニル－２－ピロリドンを好ましく採用し得る。窒素原子を有するモノマーの他の好適例としては、（メタ）アクリルアミドが挙げられる。 The copolymerizable monomers may contain nitrogen atom-containing monomers. By using a monomer having a nitrogen atom, the cohesive force of the pressure-sensitive adhesive layer (A) can be increased, and the peel strength after photocuring can preferably be improved. A suitable example of the nitrogen atom-containing monomer is a nitrogen atom-containing ring monomer. As the monomer having a nitrogen atom-containing ring, those exemplified above can be used. For example, general formula (1):

N-vinyl cyclic amides represented by can be used. Here, in general formula (1), R ¹ is a divalent organic group, specifically -(CH ₂ ) _n -. n is an integer from 2 to 7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably employed. Another suitable example of a monomer having a nitrogen atom is (meth)acrylamide.

When a monomer having a nitrogen atom (preferably a monomer having a nitrogen atom-containing ring such as N-vinyl cyclic amide) is used, the amount used is not particularly limited, and is, for example, 1% by weight or more of the total monomer components. 2% by weight or more, 3% by weight or more, or 5% by weight or more, or 7% by weight or more. In one aspect, the amount of the nitrogen atom-containing monomer used may be 10% by weight or more, 15% by weight or more, or 20% by weight or more of the total monomer components. In addition, the amount of the nitrogen atom-containing monomer used is, for example, 40% by weight or less of the total monomer components, and may be 35% by weight or less, 30% by weight or less, or 25% by weight or less. good. In another aspect, the amount of the nitrogen atom-containing monomer used may be, for example, 20% by weight or less, or 15% by weight or less, of the total monomer components. Alternatively, the nitrogen atom-containing monomer may not be used as the copolymerizable monomer.

The copolymerizable monomer may contain a hydroxyl group-containing monomer. By using a hydroxyl group-containing monomer, the degree of cohesion and cross-linking (for example, cross-linking by an isocyanate cross-linking agent) of the pressure-sensitive adhesive layer (A) can be adjusted favorably. The amount used when using a hydroxyl group-containing monomer is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, or 0.5% by weight or more of the total monomer components. It may be 1% by weight or more, 5% by weight or more, or 10% by weight or more. Moreover, from the viewpoint of suppressing water absorption of the pressure-sensitive adhesive layer (A) or its photocured product, in some embodiments, the amount of the hydroxyl group-containing monomer used is, for example, 40% by weight or less of the total monomer components. Yes, it may be 30% by weight or less, 25% by weight or less, or 20% by weight or less. In another aspect, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total monomer components. Alternatively, a hydroxyl group-containing monomer may not be used as the copolymerizable monomer.

The ratio of the carboxy group-containing monomer to the total monomer component may be, for example, 2% by weight or less, 1% by weight or less, or 0.5% by weight or less (for example, less than 0.1% by weight). The pressure-sensitive adhesive composition (A) may be substantially free of carboxy group-containing monomers as its constituent monomer components. Here, "substantially free of carboxy group-containing monomers" means that carboxy group-containing monomers are not used at least intentionally. This can be advantageous from the viewpoint of metal corrosion prevention of the pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition (A) and its photocured product.

The copolymerizable monomer may contain an alicyclic hydrocarbon group-containing (meth)acrylate. Thereby, the cohesive force of the pressure-sensitive adhesive layer (A) can be increased, and the peel strength after photocuring can be improved. As the alicyclic hydrocarbon group-containing (meth)acrylate, those exemplified above can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably employed. The amount of the alicyclic hydrocarbon group-containing (meth)acrylate used is not particularly limited, and can be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the total monomer components. In one aspect, the amount of the alicyclic hydrocarbon group-containing (meth)acrylate used may be 10% by weight or more, or 15% by weight or more, of the total monomer components. The upper limit of the amount of the alicyclic hydrocarbon group-containing (meth)acrylate used is suitably about 40% by weight or less, and may be, for example, 30% by weight or less, or 25% by weight or less (e.g., 15% by weight). % or less, or even 10% by weight or less). Alternatively, the alicyclic hydrocarbon group-containing (meth)acrylate may not be used as the copolymerizable monomer.

The copolymerizable monomers may include alkoxysilyl group-containing monomers. The alkoxysilyl group-containing monomer is typically an ethylenically unsaturated compound having at least one (preferably two or more, for example two or three) alkoxysilyl groups in one molecule. are as described above. The alkoxysilyl group-containing monomers may be used singly or in combination of two or more. By using an alkoxysilyl group-containing monomer, a crosslinked structure can be introduced into the pressure-sensitive adhesive layer (A) by a condensation reaction of silanol groups (silanol condensation).

The amount of the alkoxysilyl group-containing monomer is not particularly limited. In some aspects, the amount of the alkoxysilyl group-containing monomer used can be, for example, 0.005% by weight or more, usually 0.01% by weight, of the total monomer components constituting the pressure-sensitive adhesive composition (A). 0.03% by weight or more, or 0.05% by weight or more. In addition, from the viewpoint of the step absorbability of the pressure-sensitive adhesive composition (A), the amount of the alkoxysilyl group-containing monomer used is usually 1.0% by weight or less based on the total monomer components, and 0.5% by weight or less. % by weight or less, or 0.1% by weight or less.

Still other examples of compounds that can be used as the ethylenically unsaturated compound (B) include polyfunctional monomers. According to the pressure-sensitive adhesive composition (A) containing a polyfunctional monomer, the polyfunctional monomer is obtained by reacting the polyfunctional monomer when curing the composition to produce the pressure-sensitive adhesive layer (A). A crosslinked pressure-sensitive adhesive layer (A) can be obtained. Examples of polyfunctional monomers include 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene 2, such as glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, and divinylbenzene; Functional monomer; Trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. ; In addition, epoxy acrylate, polyester acrylate, urethane acrylate, etc.; Among them, preferred examples include 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

When using a polyfunctional monomer, the amount used is not particularly limited, and can be less than 5.0% by weight of the total monomer components constituting the pressure-sensitive adhesive composition (A). As a result, it is possible to avoid excessive formation of a crosslinked structure during the formation of the pressure-sensitive adhesive layer (A) (that is, at the stage before photocuring), and to increase the step absorbability of the pressure-sensitive adhesive layer (A). . The amount of the polyfunctional monomer used may be, for example, 4.0% by weight or less, 3.0% by weight or less, 2.0% by weight or less, or 1.0% by weight of the total monomer components. or less, 0.5% by weight or less, or 0.3% by weight or less. There is no need to use polyfunctional monomers. Further, in some aspects, from the viewpoint of imparting appropriate cohesiveness to the pressure-sensitive adhesive layer (A), the amount of the polyfunctional monomer used relative to the total monomer components may be, for example, 0.001% by weight or more, It may be 0.005% by weight or more, 0.01% by weight or more, or 0.03% by weight or more.

The weight ratio of the BP polymer (A) to the total amount of the BP polymer (A) and the ethylenically unsaturated compound (B) contained in the pressure-sensitive adhesive composition (A) is not particularly limited. The level difference absorbability of the pressure-sensitive adhesive layer (A) formed from (A) and the workability of the photocured product thereof can be set so as to be well balanced. In some embodiments, the weight fraction of the BP polymer (A) may be, for example, 0.5 wt% or more, typically 1 wt% or more, preferably 1.5 wt% or more, more preferably 5 wt% or more. It is suitable that it is at least 10% by weight, from the viewpoint of enhancing the effect of photocuring, it may be at least 10% by weight, may be at least 15% by weight, may be at least 25% by weight, may be at least 35% by weight, and may be at least 45% by weight. or more, or 55% by weight or more. Further, from the viewpoint of ease of preparation and coating properties of the pressure-sensitive adhesive composition (A), in some embodiments, the weight ratio of the BP polymer (A) to the total amount is, for example, less than 99% by weight. may be less than 95 wt%, less than 85 wt%, less than 70 wt%, less than 50 wt%, less than 40 wt%.

The proportion of the weight of the organic solvent in the total weight of the adhesive composition (A) may be, for example, 30% by weight or less, advantageously 20% by weight or less, and 10% by weight or less. is preferred, and 5% by weight or less is more preferred. In some embodiments, the weight percentage of the organic solvent may be 3% by weight or less, 1% by weight or less, 0.5% by weight or less, 0.1% by weight or less, or 0.05% by weight. % or less, and may contain substantially no organic solvent.

The pressure-sensitive adhesive composition (A) is measured under the conditions of viscosity (BH type viscometer, No. 5 rotor, 10 rpm, measurement temperature of 30 ° C.) from the viewpoint of coatability in the normal temperature range. ) is suitably 1000 Pa·s or less, preferably 100 Pa·s or less, and more preferably 50 Pa·s or less. The viscosity of the pressure-sensitive adhesive composition (A) may be, for example, 30 Pa·s or less, 20 Pa·s or less, 10 Pa·s or less, or 5 Pa·s or less. The lower limit of the viscosity of the pressure-sensitive adhesive composition (A) is not particularly limited. .1 Pa·s or more is suitable, 0.5 Pa·s or more may be sufficient, or 1 Pa·s or more may be used.

The pressure-sensitive adhesive composition (A) may contain at least a compound having one ethylenically unsaturated group (that is, a monofunctional monomer) (B1) as the ethylenically unsaturated compound (B). The monofunctional monomer (B1) can be used by selecting a corresponding compound from the examples of the ethylenically unsaturated compound (B) described above. A monofunctional monomer can be used individually by 1 type or in combination of 2 or more types.

Among the total amount of the BP polymer (A) and the ethylenically unsaturated compound (B), the weight ratio of the monofunctional monomer (B1) may be, for example, 1% by weight or more, or 5% by weight or more, It may be 15% by weight or more. In some aspects, the weight ratio of the monofunctional monomer (B1) may be 25% by weight or more, or 35% by weight or more, from the viewpoint of ease of preparation and coatability of the pressure-sensitive adhesive composition (A). or 45% by weight or more. In addition, the weight ratio of the monofunctional monomer (B1) in the total amount may be, for example, 99% by weight or less, usually 95% by weight or less, and may be 85% by weight or less. It may be 75% by weight or less, 65% by weight or less, 55% by weight or less, or 45% by weight or less.

In the aspect in which the pressure-sensitive adhesive composition (A) contains the monofunctional monomer (B1), the glass transition temperature (Tg) determined by the Fox formula based on the composition of the monofunctional monomer (B1) is not particularly limited. However, the temperature may be -80° C. or higher and 250° C. or lower, for example. Tg based on the composition of the monofunctional monomer (B1) is usually preferably 150° C. or less from the viewpoint of compatibility between the polymer derived from the monofunctional monomer (B1) and other components, It may be 100° C. or lower, 70° C. or lower, 50° C. or lower, or 30° C. or lower. In some embodiments, the Tg based on the composition of the monofunctional monomer (B1) is preferably less than 0° C., and is −10° C. or less, from the viewpoint of step absorbability of the pressure-sensitive adhesive layer (A). It is more preferably -20°C or lower, -30°C or lower, or -40°C or lower. From the viewpoint of cohesiveness of the pressure-sensitive adhesive layer (A) and workability after photocuring, the Tg based on the composition of the monofunctional monomer (B1) is usually -60° C. or higher. It may be -54°C or higher, -50°C or higher, -45°C or higher, -35°C or higher, or -25°C or higher. The above Tg can be adjusted by the compounds used as monofunctional monomers and their usage ratios.

In a pressure-sensitive adhesive composition (A) containing a BP polymer (A) and a monofunctional monomer (B1), a pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition, and a photocured product thereof, the BP polymer (A) The Tg (hereinafter referred to as “Tg _A ”) of the monofunctional monomer (B1) based on the monomer composition (hereinafter also referred to as Tg _B1 ”) is calculated by Tg _B1 [° C.]−Tg _A [° C.] The calculated Tg difference [°C] (hereinafter also referred to as ΔTg) can be set, for example, within the range of -50°C or higher and 70°C or lower. It is advantageous from the viewpoint of compatibility in the pressure-sensitive adhesive layer (A) and its photocured product that the absolute value of the Tg difference is not too large. In some embodiments, ΔTg may be, for example, −10° C. or higher, preferably 0° C. or higher, 7° C. or higher, 10° C. or higher, 20° C. or higher, or 30° C. or higher. good.

The pressure-sensitive adhesive composition (A) may contain at least a compound having two or more ethylenically unsaturated groups (that is, a polyfunctional monomer) (B2) as the ethylenically unsaturated compound (B). The polyfunctional monomer (B2) can be used singly or in combination of two or more of the polyfunctional monomers exemplified above. The amount of the polyfunctional monomer (B2) used can be set in the same manner as the ratio of the polyfunctional monomer to the total monomer components constituting the pressure-sensitive adhesive composition (A).

In an aspect in which a monofunctional monomer (B1) and a polyfunctional monomer (B2) are used in combination as the ethylenically unsaturated compound (B), the weight of the monofunctional monomer (B1) in the ethylenically unsaturated compound (B) The proportion may be, for example, 1% by weight or more, usually 25% by weight or more, may be 50% by weight or more, may be 75% by weight or more, may be 95% by weight or more, or may be 99% by weight. % or more. Moreover, the weight ratio of the monofunctional monomer (B1) to the ethylenically unsaturated compound (B) may be, for example, 99.9% by weight or less, or may be 99.8% by weight or less.

In the pressure-sensitive adhesive composition (A), the ethylenically unsaturated compound (B) may be contained in the form of a partially polymerized product, or may be contained entirely in the form of unreacted monomers. A pressure-sensitive adhesive composition (A) according to a preferred embodiment contains an ethylenically unsaturated compound (B) in the form of a partially polymerized product. The polymerization method for partially polymerizing the ethylenically unsaturated compound (B) is not particularly limited, and includes, for example: photopolymerization by irradiating light such as ultraviolet rays; Polymerization; thermal polymerization such as solution polymerization, emulsion polymerization, bulk polymerization; and the like can be appropriately selected and used from various conventionally known polymerization methods. A photopolymerization method can be preferably employed from the viewpoint of efficiency and convenience. According to photopolymerization, the polymerization conversion rate (monomer conversion) can be easily controlled by the polymerization conditions such as the irradiation amount of light (light amount).

The polymerization conversion rate of the ethylenically unsaturated compound (B) in the partially polymerized product is not particularly limited. From the viewpoint of ease of preparation and coating properties of the pressure-sensitive adhesive composition (A), the polymerization conversion rate is usually about 50% by weight or less, and about 40% by weight or less (for example, about 35% by weight). % by weight or less). Although the lower limit of the polymerization conversion rate is not particularly limited, it is typically about 1% by weight or more, and usually about 5% by weight or more is suitable.

The pressure-sensitive adhesive composition (A) containing a partially polymerized product of the ethylenically unsaturated compound (B) is, for example, a monomer mixture containing the total amount of the ethylenically unsaturated compound (B) used in the preparation of the pressure-sensitive adhesive composition. It can be obtained by partial polymerization by an appropriate polymerization method (for example, photopolymerization method). In addition, the pressure-sensitive adhesive composition (A) containing the partially polymerized product of the ethylenically unsaturated compound (B) contains part of the ethylenically unsaturated compound (B) used in the preparation of the pressure-sensitive adhesive composition. It may be a mixture of a partially polymerized product of the monomer mixture and the remaining ethylenically unsaturated compound (B) or a partially polymerized product thereof. In the present specification, the term "completely polymerized product" means that the polymerization conversion rate is over 95% by weight.

The partially polymerized product can be prepared, for example, by irradiating the ethylenically unsaturated compound (B) with ultraviolet rays. When the above partial polymer is prepared in the presence of the BP polymer (A), the ethylenically unsaturated groups are reacted and the conditions for ultraviolet irradiation are set so that the benzophenone structure is not photoexcited. A pressure-sensitive adhesive composition (A) containing a partial polymer of compound (B) and BP polymer (A) can be obtained. As the light source, a light source that can irradiate ultraviolet rays that do not contain components with a wavelength of less than 300 nm or have a small amount of components with wavelengths of less than 300 nm, such as the above-described black light and UV-LED lamp, can be preferably employed.

Moreover, after preparing a partial polymer of the ethylenically unsaturated compound (B) in advance, the partial polymer and the BP polymer (A) may be mixed to prepare the adhesive composition (A). When preparing the partial polymer by irradiating the ethylenically unsaturated compound (B) with ultraviolet rays in the absence of a benzophenone structure-containing component, the ultraviolet light source includes a light source that does not excite the benzophenone structure and a light source that excites it. Either can be used.

In preparing the partially polymerized product of the ethylenically unsaturated compound (B), the reaction of the ethylenically unsaturated groups can be promoted by using a photopolymerization initiator. Examples of photopolymerization initiators include ketal photopolymerization initiators, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, acylphosphine oxide photopolymerization initiators, α-ketol photopolymerization initiators, and aromatic sulfonyl. Chloride photoinitiator, photoactive oxime photoinitiator, benzoin photoinitiator, benzyl photoinitiator, benzophenone photoinitiator, alkylphenone photoinitiator, thioxanthone photoinitiator agents and the like can be used. A photopolymerization initiator that absorbs light with a wavelength of 300 nm or more (for example, light with a wavelength of 300 nm or more and 500 nm or less) to generate radicals can be preferably used. A photoinitiator can be used individually by 1 type or in combination of 2 or more types as appropriate.

[Photoinitiator]
The pressure-sensitive adhesive composition (A) may contain a photopolymerization initiator, if necessary, for the purpose of improving or imparting photocurability. When the pressure-sensitive adhesive composition (A) is a solventless (active energy ray-curable) pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition (A) preferably contains a photopolymerization initiator. On the other hand, when the pressure-sensitive adhesive composition (A) is a solvent-type or emulsion-type pressure-sensitive adhesive composition, it may not contain a photopolymerization initiator.

Examples of photopolymerization initiators include ketal photopolymerization initiators, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, acylphosphine oxide photopolymerization initiators, α-ketol photopolymerization initiators, and aromatic sulfonyl. Chloride photoinitiator, photoactive oxime photoinitiator, benzoin photoinitiator, benzyl photoinitiator, benzophenone photoinitiator, alkylphenone photoinitiator, thioxanthone photoinitiator agents and the like can be used. A photoinitiator can be used individually by 1 type or in combination of 2 or more types as appropriate.

Specific examples of ketal photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one and the like.
Specific examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexyl-phenyl-ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methoxyacetophenone, and the like.
Specific examples of benzoin ether photoinitiators include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, and substituted benzoin ethers such as anisole methyl ether.
Specific examples of acylphosphine oxide photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxy phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and the like.
Specific examples of α-ketol photopolymerization initiators include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, and the like. be
Specific examples of aromatic sulfonyl chloride photopolymerization initiators include 2-naphthalenesulfonyl chloride and the like.
Specific examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime and the like.
Specific examples of the benzoin-based photopolymerization initiator include benzoin and the like.
Specific examples of benzyl-based photopolymerization initiators include benzyl and the like.
Specific examples of benzophenone-based photopolymerization initiators include benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenylketone, and the like.
Specific examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and isopropylthioxanthone. , 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

As the photopolymerization initiator to be contained in the pressure-sensitive adhesive composition (A), a photopolymerization initiator that absorbs light with a wavelength of 300 nm or more (for example, light with a wavelength of 300 nm or more and 500 nm or less) to generate radicals (“photopolymerization initiator (C)”) can be preferably employed. When the pressure-sensitive adhesive composition (A) contains the photopolymerization initiator (C), it is preferable for curing the pressure-sensitive adhesive composition (A) into a cured product in which the benzophenone structure of the BP polymer (A) remains.

A photoinitiator can be used individually by 1 type or in combination of 2 or more types as appropriate. In some embodiments, a photopolymerization initiator that does not contain a phosphorus element in its molecule can be preferably employed. The pressure-sensitive adhesive composition (A) may substantially contain no photopolymerization initiator containing phosphorus element in its molecule.

The content of the photopolymerization initiator in the pressure-sensitive adhesive composition (A) is not particularly limited, and can be set so that the desired effects are appropriately exhibited. In some aspects, the content of the photopolymerization initiator can be, for example, approximately 0.005 parts by weight or more with respect to 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A). It is suitable to be 0.01 parts by weight or more, preferably 0.05 parts by weight or more, may be 0.10 parts by weight or more, may be 0.15 parts by weight or more, or may be 0.20 parts by weight. It may be more than part. By increasing the content of the photopolymerization initiator, the photocurability of the pressure-sensitive adhesive composition (A) is improved. In addition, the content of the photopolymerization initiator with respect to 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A) is usually suitably 5 parts by weight or less, preferably 2 parts by weight or less. , 1 part by weight or less, 0.7 parts by weight or less, or 0.5 parts by weight or less. It may be advantageous from the viewpoint of suppressing gelation of the pressure-sensitive adhesive composition (A) and the like that the content of the photopolymerization initiator is not too large.

[Crosslinking agent]
The pressure-sensitive adhesive composition (A) may optionally contain, for example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an oxazoline-based cross-linking agent, an aziridine-based cross-linking agent, a carbodiimide-based cross-linking agent, a melamine-based cross-linking agent, and a urea-based cross-linking agent. , a metal alkoxide-based cross-linking agent, a metal chelate-based cross-linking agent, a metal salt-based cross-linking agent, a hydrazine-based cross-linking agent, an amine-based cross-linking agent, and the like. A peroxide may be used as a cross-linking agent. When the pressure-sensitive adhesive composition (A) is a solvent-type or emulsion-type pressure-sensitive adhesive composition, it preferably contains a cross-linking agent.

The said crosslinking agent can be used individually by 1 type or in combination of 2 or more types. The pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition (A) containing a cross-linking agent preferably contains the cross-linking agent mainly in the form after the cross-linking reaction. The cohesive strength of the adhesive layer (A) and the like can be appropriately adjusted by using the cross-linking agent.

When using a cross-linking agent, the amount used (when using two or more cross-linking agents, the total amount thereof) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exerts adhesive properties such as adhesive strength and cohesive strength in a well-balanced manner, the amount of the cross-linking agent used is usually It is suitable to be about 5 parts by weight or less. It may be 20 parts by weight or less. The lower limit of the amount of the cross-linking agent to be used is not particularly limited, and the amount may be more than 0 parts by weight with respect to 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A). In some embodiments, the amount of the cross-linking agent used may be, for example, 0.001 parts by weight or more, such as 0.01 parts by weight or more, relative to 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A). 0.05 parts by weight or more, or 0.10 parts by weight or more.

[Chain transfer agent]
The pressure-sensitive adhesive composition (A) may contain conventionally known various chain transfer agents. Mercaptans such as n-dodecylmercaptan, t-dodecylmercaptan, thioglycolic acid and α-thioglycerol can be used as the chain transfer agent. Alternatively, a chain transfer agent containing no sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; α-methylstyrene and α-methylstyrene dimer. styrenes such as dibenzylideneacetone, cinnamyl alcohol, compounds having a benzylidenyl group such as cinnamylaldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; 2,3-dimethyl-2-butene , olefins such as 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; A chain transfer agent can be used individually by 1 type or in combination of 2 or more types. When a chain transfer agent is used, the amount used can be, for example, about 0.01 to 1 part by weight per 100 parts by weight of the monomer component. A mode in which no chain transfer agent is used can also be preferably carried out.

Another component that can be included in the pressure-sensitive adhesive composition (A) is a silane coupling agent. The use of a silane coupling agent can improve the peel strength to an adherend (for example, a glass plate). Moreover, the adhesive layer (A) can contain a silane coupling agent. The pressure-sensitive adhesive layer (A) containing a silane coupling agent can be suitably formed using the pressure-sensitive adhesive composition (A) containing a silane coupling agent. A silane coupling agent can be used individually by 1 type or in combination of 2 or more types.

The adhesive composition (A) may contain a coloring agent. The coloring agent is not particularly limited, but a coloring agent having a maximum transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) greater than a maximum transmittance at a wavelength of 400 to 700 nm ("coloring agent ( A)”) is preferred.

When the pressure-sensitive adhesive composition (A) contains the coloring agent (A), the transparency to visible light (wavelength 400 to 700 nm) is reduced, that is, the light shielding property is improved. 200 to 400 nm, preferably 330 to 400 nm) transmittance increases.

When the pressure-sensitive adhesive composition (A) contains the colorant (A), it has low transmittance to visible light (wavelength of 400 to 700 nm), that is, high light-shielding properties. The pressure-sensitive adhesive layer (A) formed from the cured product of the pressure-sensitive adhesive composition (A) having high light-shielding properties against visible light is a metal wiring layer and a light-emitting element ( By sealing the fine steps between the LED chips without gaps, reflection due to metal wiring or the like is prevented, color mixture of the light emitting elements (LED chips) is prevented, and the contrast of the image is improved.

On the other hand, when the pressure-sensitive adhesive composition (A) contains the colorant (A), the transmittance of the ultraviolet region (wavelength 200-400 nm, preferably 330-400 nm) is higher than that of visible light. Therefore, the pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition (A) can be cured by irradiation with a high-pressure mercury lamp so that the benzophenone structure forms a crosslinked structure. The pressure-sensitive adhesive layer (A) cured by irradiation with a high-pressure mercury lamp has improved reworkability, can be easily peeled off from the display panel, and hardly remains on the display panel.

The maximum transmittance of the colorant (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, or 30% or less. , 20% or less, 10% or less, or 5% or less.

In a preferred embodiment of the present invention, the colorant (A) has a higher average transmittance at wavelengths of 200-400 nm (preferably 330-400 nm) than at 400-700 nm. The average transmittance of the colorant (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less. % or less, 10% or less, or 5% or less.

The transmittance of the colorant is adjusted by an appropriate solvent such as tetrahydrofuran (THF) or a dispersion medium (organic solvent with low absorption in the wavelength range of 200 to 700 nm) so that the transmittance at a wavelength of 400 nm is about 50 to 60%. Measurements can be made using diluted solutions or dispersions.

The colorant may be either a dye or a pigment as long as it can be dissolved or dispersed in the pressure-sensitive adhesive composition (A). Dyes are preferred because they can achieve a low haze even when added in small amounts, and are easy to distribute uniformly without sedimentation like pigments. Pigments are also preferred because they have high color development even when added in small amounts. If a pigment is used as the colorant, it preferably has low or no conductivity. Moreover, when a dye is used, it is preferable to use it together with an antioxidant or the like.

Examples of ultraviolet-transmitting black pigments include "9050BLACK", "9256BLACK", "9170BLACK" and "UVBK-0001" manufactured by Tokushiki, and "UB-1" manufactured by Mitsubishi Materials Electronic Chemicals. Examples of the ultraviolet-transmitting black dye include "SOC-L-0123" manufactured by Orient Chemical Industry Co., Ltd., and the like.

The content of the colorant in the adhesive composition (A) is, for example, about 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, relative to 100 parts by weight of the adhesive composition (A). It may be appropriately set depending on the type of coloring agent, color tone and light transmittance of the pressure-sensitive adhesive layer (A), and the like. Colorants may be added as a solution or dispersion dissolved or dispersed in a suitable solvent.

The pressure-sensitive adhesive composition (A) optionally contains a tackifying resin (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based tackifying resin), a viscosity modifier (e.g., thickener) , leveling agents, antioxidants, plasticizers, fillers, stabilizers, preservatives, anti-aging agents, and other additives commonly used in the field of adhesives may be included as other optional ingredients. As for such various additives, conventionally known ones can be used in a conventional manner, and since they do not particularly characterize the present invention, detailed description thereof will be omitted.

In addition, the pressure-sensitive adhesive composition (A) can exhibit good adhesive strength without using the above-described tackifying resin. Therefore, in some embodiments, the content of the tackifying resin in the pressure-sensitive adhesive layer (A) or the pressure-sensitive adhesive composition (A) is, for example, less than 10 parts by weight relative to 100 parts by weight of the monomer component, and further can be less than 5 parts by weight. The content of the tackifying resin may be less than 1 part by weight (for example, less than 0.5 parts by weight), or less than 0.1 parts by weight (0 parts by weight or more and less than 0.1 parts by weight). good. The pressure-sensitive adhesive layer (A) or pressure-sensitive adhesive composition (A) may not contain a tackifying resin.

The pressure-sensitive adhesive layer (A) is preferably a cured product of the pressure-sensitive adhesive composition (A) in which the benzophenone structure remains. This benzophenone structure can form a crosslinked structure by irradiation with a high-pressure mercury lamp to cure the pressure-sensitive adhesive layer (A). The pressure-sensitive adhesive layer (A) before curing is in a semi-cured state with high fluidity and exhibits excellent level difference absorbability. Therefore, when the pressure-sensitive adhesive layer (A) of the photocurable pressure-sensitive adhesive sheet of the present invention is attached to a display panel in which optical semiconductor elements (LED chips) are arranged at high density, fine particles between the optical semiconductor elements (LED chips) Adheres closely to any gaps without leaving any air bubbles. On the other hand, the adhesive layer (A) after curing exhibits excellent reworkability. Therefore, the cured pressure-sensitive adhesive layer (A) can be easily peeled off from the optical semiconductor element of the display panel and hardly remains on the display panel. Thus, according to the pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition (A), both excellent step absorbability and reworkability can be suitably achieved.

In addition, by controlling the irradiation amount of the high-pressure mercury lamp that irradiates the adhesive layer (A), the laminate containing the adhesive layer (A) as a sealing material is cut and the adhesive is missing during cutting, and from the edge during storage. It is also possible to suppress the protrusion and sagging of the pressure-sensitive adhesive layer and improve the workability.

The method for producing the pressure-sensitive adhesive layer (A) is not particularly limited. Specifically, the pressure-sensitive adhesive composition (A) is applied (coated) onto a substrate or a release liner, and if necessary, dried, cured, or dried and cured.

A known coating method may be used for the application (coating) of the pressure-sensitive adhesive composition (A). For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters may be used.

When the pressure-sensitive adhesive composition (A) is cured by irradiation with active energy rays, the ethylenically unsaturated groups contained in the pressure-sensitive adhesive composition (A) are reacted, and the benzophenone contained in the pressure-sensitive adhesive layer (A) It is preferably carried out so as to leave the structure intact. As the active energy ray for forming the pressure-sensitive adhesive layer (A), ultraviolet rays are preferable, and ultraviolet rays containing no or less wavelength components with a wavelength of less than 300 nm, preferably less than 350 nm, are more preferable.

When the pressure-sensitive adhesive composition (A) contains the BP polymer (A) and the ethylenically unsaturated compound (B), the pressure-sensitive adhesive layer (A) contains the BP polymer (A) and the ethylenically unsaturated compound (B ) and a polymer (E) derived from In this aspect, the pressure-sensitive adhesive composition (A) may be a composition in which the ethylenically unsaturated compound (B) does not contain ethylenically unsaturated BP. According to the adhesive composition (A) having such a composition, the BP polymer (A) and the polymer (E) derived from the ethylenically unsaturated compound (B) are included, and the polymer (E) has a benzophenone structure A pressure-sensitive adhesive layer (A) that is a polymer (sometimes referred to as a [non-BP polymer]) having no

On the other hand, when the pressure-sensitive adhesive composition (A) contains a mixture of monomer components constituting the BP polymer (A) or a partially polymerized mixture of the monomer components, the pressure-sensitive adhesive layer (A) has two different monomer compositions. It may be a pressure-sensitive adhesive layer containing at least one polymer, wherein at least one of the two or more polymers is a polymer having a benzophenone structure in its side chain (sometimes referred to as "BP polymer (A')"). . The pressure-sensitive adhesive layer may contain only two or more BP polymers (A') as the two or more polymers, or may contain a combination of a non-BP polymer and a BP polymer (A'). good. A non-BP polymer can be formed by using an adhesive composition containing an ethylenically unsaturated compound that does not have a benzophenone structure and polymerizing the ethylenically unsaturated compound. The BP polymer (A') may be, for example, the BP polymer (A) contained in the pressure-sensitive adhesive composition (A), or may be a modified product thereof, and the pressure-sensitive adhesive composition ( It may be formed by copolymerizing the ethylenically unsaturated BP contained in A) with other ethylenically unsaturated BP.
The two or more polymers may or may not be chemically bonded. The pressure-sensitive adhesive layer (A) according to some embodiments may contain at least one BP polymer in a form that is not chemically bonded to polymers other than the BP polymer.

Irradiation with active energy rays for curing the pressure-sensitive adhesive composition (A) is preferably carried out so as to react the ethylenically unsaturated groups and leave the benzophenone structure. As the pressure-sensitive adhesive composition (A), a pressure-sensitive adhesive composition containing a BP polymer (A) and an ethylenically unsaturated compound (B) can be preferably used. The light source for curing the pressure-sensitive adhesive composition (A) to form a photocrosslinkable pressure-sensitive adhesive includes a component having a wavelength of less than 300 nm, preferably less than 350 nm, such as the above-described black light or UV-LED lamp. A light source capable of irradiating ultraviolet rays having no or little wavelength component can be preferably employed.

In a preferred embodiment of the present invention, the pressure-sensitive adhesive layer (A) has a maximum transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) greater than the maximum transmittance at a wavelength of 400 to 700 nm. . Adhesive layer (A), which has excellent light shielding properties against visible light, seals minute steps between metal wiring layers and optical semiconductor elements (LED chips) of self-luminous display devices (mini/micro LED display devices) without gaps. As a result, reflection by metal wiring or the like is prevented, color mixture of the optical semiconductor element (LED chip) is prevented, and the contrast of the image is improved. On the other hand, the pressure-sensitive adhesive layer (A) having a high transmittance in the ultraviolet region (200 to 400 nm wavelength, preferably 330 to 400 nm wavelength) is cured by irradiation with a high-pressure mercury lamp so that the benzophenone structure forms a crosslinked structure. As a result, the reworkability is improved, the optical semiconductor element of the display panel can be easily peeled off, and it is less likely to remain on the display panel.

In a preferred embodiment of the present invention, the maximum transmittance of the pressure-sensitive adhesive layer of the present invention at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, It may be 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less.

In a preferred embodiment of the present invention, the pressure-sensitive adhesive layer of the present invention has a higher average transmittance at wavelengths of 200-400 nm (preferably 330-400 nm) than at 400-700 nm. The average transmittance of the pressure-sensitive adhesive layer of the present invention at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less. % or less, 10% or less, or 5% or less.

The pressure-sensitive adhesive layer (A) preferably contains, for example, about 0.1 mg or more of a benzophenone structure in terms of 4-benzoylphenyl acrylate per 1 g of the pressure-sensitive adhesive layer. Hereinafter, the weight of the benzophenone structure contained per 1 g of the pressure-sensitive adhesive layer of the present invention in terms of 4-benzoylphenyl acrylate is sometimes referred to as the BP equivalent (unit: mg/g) of the pressure-sensitive adhesive layer. From the viewpoint of obtaining a higher photocuring effect (for example, an effect of improving reworkability by photocuring), the BP equivalent of the pressure-sensitive adhesive layer is usually suitably 0.3 mg/g or more, and 0.5 mg/g. g or more, 1 mg/g or more, 5 mg/g or more, 10 mg/g or more, or 20 mg/g or more. In addition, from the viewpoint of the impact resistance of the joint due to the photocured product and the suppression of distortion in the photocured product, the BP equivalent of the pressure-sensitive adhesive layer is usually suitably 100 mg / g or less, and 80 mg / g or less. 60 mg/g or less, 40 mg/g or less, 25 mg/g or less, or 15 mg/g or less.

The high-pressure mercury lamp irradiation conditions for the pressure-sensitive adhesive layer of the present invention are not particularly limited, but ultraviolet rays with a wavelength of 200 to 280 nm are preferably included. The UV-LED irradiation conditions for the pressure-sensitive adhesive layer of the present invention are not particularly limited, but preferably include ultraviolet rays with a wavelength of 350 nm or more and no or little ultraviolet rays with a wavelength of 200 to 280 nm. Lamps, chemical lamps and black lights can also be used. In addition, the irradiation energy, irradiation time, and irradiation method of the radiation for curing can be appropriately set as long as they do not adversely affect the adherend. For example, the irradiation amount (accumulated light amount) is preferably 1000 mJ/cm ² to 10000 mJ/cm ² , more preferably 2000 mJ/cm ² to 4000 mJ/cm ² , still more preferably 3000 mJ/cm ² .

[VOC emission amount]
The VOC (volatile organic compound) emission amount of the pressure-sensitive adhesive layer of the present invention is not particularly limited. The VOC emission amount may be, for example, 5000 μg/g or less, 3000 μg/g or less, or 1000 μg/g or less. In some aspects, the VOC emission amount of the pressure-sensitive adhesive layer of the present invention is preferably 500 μg/g or less, more preferably 300 μg/g or less, and even more preferably 100 μg/g or less. A pressure-sensitive adhesive layer that emits a small amount of VOCs has a low odor and is preferable from the viewpoint of environmental hygiene. A low VOC emission amount in the pressure-sensitive adhesive layer of the present invention is also preferable from the viewpoint of suppression of foaming caused by volatile organic substances (VOC) in the pressure-sensitive adhesive layer and low contamination. The VOC emission amount of the pressure-sensitive adhesive layer of the present invention is measured by the following method using an appropriate amount (for example, about 1 mg to 2 mg) of the pressure-sensitive adhesive layer as a measurement sample. Note that the thickness of the measurement sample is preferably 1 mm or less.

(Gel fraction)
The gel fraction of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but from the viewpoint of the cohesion of the pressure-sensitive adhesive layer and the handleability of the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer, it is usually 5% or more. It is suitable, preferably 15% or more, may be 25% or more, or may be 35% or more. In principle, the gel fraction of the pressure-sensitive adhesive layer of the present invention is 100% or less. Further, from the viewpoint of absorbability of unevenness on the surface shape of the adherend, the gel fraction of the pressure-sensitive adhesive layer of the present invention is preferably less than 85%, may be less than 70%, may be less than 55%, and may be less than 40%. may be less than %.

A gel fraction is measured by the following method. That is, about 0.5 g of a measurement sample is accurately weighed, and its weight is defined as W1. After wrapping this measurement sample in a porous PTFE (polytetrafluoroethylene) sheet and immersing it in ethyl acetate at room temperature for one week, it was dried and the weight W2 of the ethyl acetate insoluble portion was measured. formula:
Gel fraction (%) = W2/W1 x 100;
to calculate the gel fraction. As the porous PTFE sheet, Nitto Denko's trade name "Nitoflon NTF1122" or its equivalent can be used.

In some aspects of the pressure-sensitive adhesive layer of the present invention, a photocured product obtained by irradiating the pressure-sensitive adhesive layer with ultraviolet rays using a high-pressure mercury lamp under the conditions of an illumination intensity of 300 mW/cm ² and an integrated light intensity of 10000 mJ/cm ² . may be, for example, 70% or more, preferably 90% or more, may be 95% or more, or may be 98% or more. The gel fraction of the photocured product is, in principle, 100% or less. The gel fraction is measured by the method described above.
The gel fraction of the pressure-sensitive adhesive layer of the present invention is the composition of the pressure-sensitive adhesive composition (A) (e.g., Mw, Tg, BP equivalent of BP polymer (A); weight fraction of BP polymer (A); BP polymer ( A) and the composition of the monomer components constituting the ethylenically unsaturated compound (B), the type and amount of the functional group; the type and amount of the cross-linking agent), the adhesive composition (A), and the curing of the adhesive layer of the present invention. It can be adjusted by conditions (heating conditions, ultraviolet irradiation conditions) and the like.

The glass transition point (Tg) of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably −60 to 20° C., more preferably −40 to 10° C., still more preferably −30 to 0°C. If the Tg is higher than 20°C, the adhesive strength cannot be exhibited at room temperature.

The Tg is not particularly limited, but can be measured according to JIS K 7121 by differential scanning calorimetry (DSC) using the pressure-sensitive adhesive layer as a measurement sample. Specifically, for example, a device name "Q-2000" manufactured by TA Instruments Co., Ltd. can be used as a measuring device, and the temperature can be measured from -80°C to 80°C at a temperature increase rate of 10°C/min.

The thickness of the pressure-sensitive adhesive layer of the present invention is not particularly limited, and may be appropriately set so as to sufficiently seal optical semiconductor elements arranged on a display panel, which will be described later. For example, the thickness of the adhesive layer of the present invention is 1.0 to 4.0 times, preferably 1.1 to 3.0 times, more preferably 1.2 to 2.5 times the height of the optical semiconductor element. It is adjusted to double, more preferably 1.3 to 2.0 times. By setting the thickness to 1.0 times or more, the pressure-sensitive adhesive layer can easily follow the steps, and the step absorbability is improved. Further, by setting the thickness to 4.0 or less, the reworkability of the pressure-sensitive adhesive layer is improved.

The pressure-sensitive adhesive layer (A) can be photocrosslinked, for example, by irradiating with ultraviolet light containing a wavelength component capable of exciting the benzophenone structure. It is preferable to use a high-pressure mercury lamp as a light source capable of irradiating ultraviolet rays containing components having a wavelength of less than 300 nm, for example, 200 to 280 nm. The light emitted from the light source may contain a component with a wavelength of 300 nm or longer.

As a light source capable of irradiating ultraviolet light that does not contain or has little wavelength component that can excite the benzophenone structure (for example, a component with a wavelength of less than 300 nm, preferably a component with a wavelength of less than 350 nm), black light, UV-LED. A lamp etc. are mentioned. These light sources can be preferably employed as light sources for advancing the reaction (polymerization reaction or curing reaction) of the ethylenically unsaturated groups by light irradiation performed in the presence of the benzophenone structure. In ultraviolet irradiation for reacting the ethylenically unsaturated groups, the above photopolymerization initiators can be used to promote the reaction.

The pressure-sensitive adhesive layer of the present invention may have a composition that does not substantially contain a photopolymerization initiator that absorbs light with a wavelength of 300 nm or longer to generate radicals. The composition may be substantially free of photopolymerization initiators that generate radicals. This can be advantageous from the viewpoint of the optical properties of the adhesive layer of the present invention. It should be noted that not containing a photopolymerization initiator that absorbs light with a wavelength of 300 nm or more to generate radicals means that the photopolymerization initiator in a form capable of generating radicals (a form having a site that is cleaved by light) is used. It is permissible to contain the cleavage residue of the photopolymerization initiator. The pressure-sensitive adhesive layer of the present invention according to a preferred embodiment does not substantially contain a photopolymerization initiator containing a phosphorus element in its molecule. The pressure-sensitive adhesive layer disclosed herein may substantially contain neither a photopolymerization initiator containing a phosphorus element in its molecule nor a cleavage residue of the photopolymerization initiator.

The photocurable pressure-sensitive adhesive sheet of the present invention may be a pressure-sensitive adhesive sheet with a substrate, as described above. Examples of such substrates include various optical films such as plastic films, antireflection (AR) films, polarizing plates, and retardation plates. Materials for the plastic film include, for example, polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, Polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, trade name “Arton” (cyclic olefin polymer, manufactured by JSR Corporation), trade name “Zeonor” (cyclic olefin polymer, Nippon Zeon Co., Ltd.) company)” and other plastic materials such as cyclic olefin polymers. These plastic materials may be used alone or in combination of two or more.

The substrate is preferably transparent. The total light transmittance (according to JIS K7361-1) of the base material in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more. Moreover, the haze (according to JIS K7136) of the substrate is not particularly limited, but is preferably 1.5% or less, more preferably 1.0% or less. Examples of such transparent substrates include PET films and non-oriented films such as the trade name "Arton" and the trade name "Zeonor".

Although the thickness of the base material is not particularly limited, it is preferably 12 to 75 μm. In addition, the substrate may have either a single-layer structure or a multilayer structure. Further, the surface of the base material may be subjected to, for example, antireflection treatment (AR treatment), antireflection treatment such as antiglare treatment, physical treatment such as corona discharge treatment and plasma treatment, and chemical treatment such as undercoating treatment. A conventional surface treatment may be appropriately applied.

The photocurable pressure-sensitive adhesive sheet of the present invention may have other pressure-sensitive adhesive layers (pressure-sensitive adhesive layers other than the pressure-sensitive adhesive layer of the present invention) as described above. The other adhesive layers are not particularly limited, but for example, urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, silicone-based adhesives, polyester-based adhesives, polyamide-based adhesives, and epoxy-based adhesives. , vinyl alkyl ether-based adhesives, fluorine-based adhesives, and other known or commonly used adhesives. In addition, the said adhesive may be used individually or in combination of 2 or more types.

In addition to the adhesive layer, substrate, and other adhesive layers of the present invention, the photocurable pressure-sensitive adhesive sheet of the present invention may include other layers (for example, an intermediate layer and a undercoat layer, etc.).

The photocurable pressure-sensitive adhesive sheet of the present invention may be provided with a release film (separator) on the pressure-sensitive adhesive surface until use. The form in which the adhesive surface of the photocurable pressure-sensitive adhesive sheet of the present invention is protected by the release film is not particularly limited. It may be in a form in which each pressure-sensitive adhesive surface is protected by one sheet of release film having release surfaces on both sides by being wound up. A release film is used as a protective material for the pressure-sensitive adhesive layer, and is peeled off when it is attached to an adherend. In addition, in the photocurable pressure-sensitive adhesive sheet of the present invention, the release film also serves as a support for the pressure-sensitive adhesive layer. Note that the release film does not necessarily have to be provided.

The release film is not particularly limited, and for example, a release film in which the surface of a film substrate such as a resin film or paper is release-treated, a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.) ) can be used. For the release treatment, for example, a release treatment agent such as a silicone-based agent or a long-chain alkyl-based agent may be used. In some aspects, a release-treated resin film can be preferably employed as the release film.

The thickness (total thickness) of the photocurable pressure-sensitive adhesive sheet of the present invention is not particularly limited, but is preferably 10 μm to 1 mm, more preferably 100 to 500 μm, still more preferably 150 to 350 μm. By setting the thickness to 10 μm or more, the pressure-sensitive adhesive layer of the present invention can easily follow the step portion, and the step absorbability can be improved. The thickness of the photocurable adhesive sheet (A) does not include the thickness of the release film.

Since the photocurable pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive layer of the present invention, it has excellent level difference absorbability before curing. For example, in addition to steps of 5 to 10 μm, the step absorbability is excellent even for high steps exceeding 40 μm. Furthermore, it has step absorbability even for high steps exceeding 80 μm.

In addition, since the photocurable pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive layer of the present invention, it cures and shrinks after irradiation with a high-pressure mercury lamp, has excellent reworkability, and can be easily peeled off from the display panel. In addition, it is difficult to remain on the display panel.
In addition, since the photocurable pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive layer of the present invention, the pressure-sensitive adhesive layer cures and shrinks due to ultraviolet rays contained in external light or light emitted from a blue optical semiconductor element, resulting in a display panel. It is possible to prevent the adhesive layer (sealing material) from peeling off.

In addition, since the photocurable pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive layer of the present invention, by controlling the irradiation amount of the high-pressure mercury lamp, it has excellent workability, and adhesive loss during cutting and storage. In some cases, the pressure-sensitive adhesive layer is prevented from sagging or sagging from the edges, and the adhesion reliability can also be improved.

<Optical semiconductor device, self-luminous display device, image display device>
The optical semiconductor device of the present invention comprises a substrate, one or more optical semiconductor elements arranged on the substrate, and the photocurable adhesive sheet of the present invention, wherein the photocurable adhesive sheet comprises the optical semiconductor The element is sealed. The optical semiconductor device of the present invention is preferably a self-luminous display device. The image display device of the present invention preferably includes the self-luminous display device of the present invention.

In the optical semiconductor device (self-luminous display device) of the present invention, a large number of minute optical semiconductor elements are arranged on a wiring substrate, and each optical semiconductor element is selectively caused to emit light by means of light emission control means connected thereto. Therefore, visual information such as characters, images, moving images, etc. can be directly displayed on the display screen by blinking of each optical semiconductor element. Examples of self-luminous display devices include mini/micro LED display devices and organic EL (electroluminescence) display devices. The photocurable pressure-sensitive adhesive sheet of the present invention is particularly suitable for manufacturing mini/micro LED display devices.

FIG. 3 is a schematic diagram (sectional view) showing one embodiment of the self-luminous display device (mini/micro LED display device) of the present invention.
In FIG. 3, the mini/micro LED display device 20 includes a display panel in which a plurality of optical semiconductor elements (LED chips) 4 are arranged on one side of a substrate 2 via a metal wiring layer 3, and laminated on the display panel, It is composed of a metal wiring layer 3, an adhesive layer 1 for sealing a plurality of optical semiconductor elements 4, and a substrate (cover member) S5 laminated on the upper portion of the adhesive layer 1 (on the image display side). The base material S5 is not particularly limited, but can be made of the same material as the "base material" described above.

In the mini/micro LED display device 20 of this embodiment, a metal wiring layer 3 for sending light emission control signals to each optical semiconductor element 4 is laminated on the substrate 2 of the display panel. Optical semiconductor elements 4 that emit red (R), green (G), and blue (B) lights are alternately arranged on a substrate 2 of the display panel via metal wiring layers 3 . The metal wiring layer 3 is made of metal such as copper, and reflects the light emitted from each optical semiconductor element 4 to reduce the visibility of the image. In addition, the light emitted from each optical semiconductor element 5 of each color of RGB is mixed, and the contrast is lowered.

In the mini/micro LED display device 20 of this embodiment, each optical semiconductor element 4 arranged on the display panel is sealed with the adhesive layer 1 . The pressure-sensitive adhesive layer 1 is composed of the pressure-sensitive adhesive layer of the present invention. The pressure-sensitive adhesive layer 1 sufficiently follows fine steps between the plurality of optical semiconductor elements 4 and seals them without gaps.

When the pressure-sensitive adhesive layer 1 contains a coloring agent, it has sufficient light shielding properties in the visible light region. When the minute steps between the optical semiconductor elements 4 are sealed without gaps by the adhesive layer 1 having a high light-shielding property, reflection by the metal wiring layer 3 can be prevented, and color mixing between the optical semiconductor elements 4 can be prevented. , the contrast can be improved.

The self-luminous display device (mini/micro LED display device) of this embodiment may include optical members other than the display panel, adhesive layer, and cover member. Examples of the optical member include, but are not particularly limited to, a polarizing plate, a retardation plate, an antireflection film, a viewing angle adjusting film, an optical compensation film, and the like. The optical member also includes members (design film, decorative film, surface protective plate, etc.) that play a role of decoration and protection while maintaining the visibility of the display device and the input device.

The self-luminous display device (mini/micro LED display device) of the present embodiment is not particularly limited, but preferably can be manufactured by a method including the following steps.
(1) A step of laminating an adhesive layer of the photocurable adhesive sheet of the present invention on a display panel in which a plurality of optical semiconductor elements are arranged on one side of a substrate, and sealing the optical semiconductor elements with the adhesive layer.

In the self-luminous display device, there is a problem that non-lighting, different colors, chipping, misalignment, etc. of the optical semiconductor elements occur, resulting in a decrease in yield. Further, when the display panel is sealed, mistakes such as wrinkling, contamination by foreign matter, and air bubbles may occur. When such a yield reduction or sealing error occurs, so-called rework is performed in which the sealing material is peeled off from the display panel, removed, and reused.

The photocurable pressure-sensitive adhesive sheet of the present invention can be improved in reworkability by irradiating it with a high-pressure mercury lamp to cure and shrink the pressure-sensitive adhesive layer of the present invention. Therefore, when the self-luminous display device such as the mini/micro LED display device of the present invention has a yield reduction or a sealing error, the pressure-sensitive adhesive layer (sealing material) of the present invention is irradiated with a high-pressure mercury lamp. As a result, the adhesive layer (sealing material) of the present invention can be easily peeled off from the substrate on the display panel and the optical semiconductor element, and little residue remains.

FIG. 4 is a schematic diagram (cross-sectional view) showing a process for carrying out one embodiment of rework of the self-luminous display device (mini/micro LED display device) of the present invention. In this embodiment, as shown in FIG. 4A, a photocurable adhesive sheet 11 of the present invention and a plurality of optical semiconductor elements (LED chips) 4 are provided on one side of a substrate 2 with a metal wiring layer 3 interposed therebetween. A display panel arranged by

In this embodiment, the photocurable adhesive sheet 11 is composed of the adhesive layer 1 and the substrate (cover member) S5. In this embodiment, the photocurable adhesive sheet 11 has the substrate S5, but the substrate S5 may be omitted. The base material S5 is not particularly limited, but can be made of the same material as the above-described "base material", and may be a release film (separator).

Next, as shown in FIG. 4(b), the adhesive layer 1 of the photocurable adhesive sheet 11 is laminated on the surface of the display panel on which the plurality of optical semiconductor elements are arranged to form the optical semiconductor elements 4 and the metal wiring. Layer 3 is sealed with adhesive layer 1 . The lamination can be performed by a known method, for example, under heating and pressurizing conditions using an autoclave. The adhesive layer 1 of the photocurable adhesive sheet 11 has high fluidity and exhibits excellent level difference absorbability. Therefore, the pressure-sensitive adhesive layer 1 is sealed so as to fill the steps between the metal wiring layer 3 and the plurality of optical semiconductor elements 4 without gaps.

In the manufactured self-luminous display device 20, the pressure-sensitive adhesive layer 1 does not undergo curing shrinkage due to external light or light contained in the blue optical semiconductor element. Peeling does not easily occur, and the durability is excellent.

In the manufactured self-luminous display device 20, if there is a decrease in yield or a sealing error such as non-lighting of the optical semiconductor element, color difference, missing, misalignment, etc., as shown in FIG. The agent layer 1 is irradiated with radiation U from a high-pressure mercury lamp to cure and shrink. Irradiation with a high-pressure mercury lamp cures and shrinks the pressure-sensitive adhesive layer 1, reducing the peeling force from the substrate 2 of the display panel and the optical semiconductor element 4, thereby improving the reworkability.

Next, as shown in FIGS. 4(d) and 4(e), the adhesive layer 1 cured and shrunk by irradiation with a high-pressure mercury lamp is peeled off from the substrate 2 of the display panel and the optical semiconductor element 4. Next, as shown in FIG. Since the cured and shrunk adhesive layer 1 is excellent in reworkability, it can be easily peeled off from the substrate 2 of the display panel and the optical semiconductor element 4 and hardly remains.

The peeled display panel can be reused by repairing the non-lighting optical semiconductor element as necessary. In addition, in the self-luminous display device shipped as an acceptable product, if a failure such as non-lighting of the optical semiconductor element occurs in the usage environment, light curing is performed by the same operation as shown in FIGS. It is also possible to repair by peeling off the adhesive sheet.

The radiation emitted by the high-pressure mercury lamp preferably includes ultraviolet rays with a wavelength of less than 300 nm, more preferably ultraviolet rays with a wavelength of 200 to 280 nm. That is, the pressure-sensitive adhesive layer of the present invention preferably cures and shrinks when irradiated with ultraviolet rays having a wavelength of 200 to 280 nm. Further, the pressure-sensitive adhesive layer of the present invention preferably cures and shrinks when irradiated with ultraviolet rays having a wavelength of 200 to 280 nm, and is resistant to curing shrinkage when irradiated with ultraviolet rays having a wavelength of 300 nm or more, preferably 350 nm or more. In such a configuration, the pressure-sensitive adhesive layer of the present invention cures and shrinks with a high-pressure mercury lamp, which is a light source containing radiation with a wavelength of 200 to 280 nm, which is not included in external light or light emitted from a blue optical semiconductor element. On the other hand, curing shrinkage does not proceed due to external light or radiation with a wavelength of 350 nm or more contained in light emitted from the blue optical semiconductor element, so that the pressure-sensitive adhesive can be used in the environment of the self-luminous display device. It is preferable in that it can prevent peeling of the layer (sealing material).

The irradiation time and irradiation method of the high-pressure mercury lamp can be appropriately selected as long as the pressure-sensitive adhesive layer 1 can be cured, the display panel is not unduly affected, and the pressure-sensitive adhesive layer 1 is cured to exhibit sufficient reworkability. can be set. For example, the irradiation dose (accumulated light dose) of ultraviolet rays is preferably 1000 mJ/cm ² to 10000 mJ/cm ² , more preferably 2000 mJ/cm ² to 4000 mJ/cm ² , still more preferably 3000 mJ/cm ² .

Further, as another embodiment, by controlling the irradiation time of the high-pressure mercury lamp and the irradiation method to be less than the above, the workability of the pressure-sensitive adhesive layer 1 is improved, and the adhesive layer 1 lacks glue during cutting, and is removed from the end during storage. Protrusion and sagging of the adhesive layer are suppressed. In addition, the pressure-sensitive adhesive layer 1 suppresses the generation of gas such as carbon dioxide due to heating of the display panel, prevents the generation of air bubbles, and improves adhesion reliability. The irradiation time and irradiation method of the high-pressure mercury lamp in this embodiment can be appropriately set as long as the display panel is not unduly affected and the pressure-sensitive adhesive layer 1 is cured to exhibit sufficient workability. can.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[Example 1]
(Preparation of prepolymer)
In a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer and a stirrer, 100 parts of n-butyl acrylate (BA), 15.9 parts of cyclohexyl acrylate (CHA), 2-hydroxyethyl acrylate (2HEA) were added as monomer components. ) 45.3 parts by weight, 4.2 parts of 4-acryloyloxybenzophenone (ABP), 202.7 parts of methyl ethyl ketone (MEK) as a polymerization solvent, and 2,2'-azobisisobutyronitrile as a thermal polymerization initiator. By adding 0.5 part of (AIBN) and carrying out solution polymerization in a nitrogen atmosphere, a solution containing an acrylic prepolymer having an Mw of 300,000 was obtained.

(Preparation of adhesive composition)
To the solution containing the acrylic prepolymer obtained above, Coronate L (trimethylolpropane/tolylene diisocyanate trimer adduct, manufactured by Tosoh Corporation) is solidified per 100 parts of the monomer component used to prepare the solution. 1 part was added on a minute basis and uniformly mixed to prepare a solvent-based pressure-sensitive adhesive composition.

(Creating an adhesive sheet)
The solvent-based adhesive composition prepared above is applied to the release surface of a 38 μm-thick release film (MRF#38, manufactured by Mitsubishi Plastics, Inc.) in which one side of the polyester film is the release surface, and the solvent-based adhesive composition is applied at 130° C. for 3 minutes. It was dried to form an adhesive sheet with a thickness of 50 μm. The release surface of a release film (manufactured by Mitsubishi Plastics, Inc., MRE #38) with a thickness of 38 μm is attached to this adhesive layer to protect it, and the adhesive layer with a thickness of about 50 μm is photocured sandwiched between the release films. A flexible adhesive sheet 1 was obtained in the form of a double-sided adhesive sheet without a substrate.

[Example 2]
A pressure-sensitive adhesive layer having a thickness of about 50 μm was sandwiched between release films in the same manner as in Example 1 except that 7.5 parts of cyclohexyl acrylate (CHA) and 12.5 parts of 4-acryloyloxybenzophenone (ABP) were added. A photocurable pressure-sensitive adhesive sheet 2 was obtained in the form of a substrate-less double-sided pressure-sensitive adhesive sheet.

[Example 3]
(Preparation of adhesive composition)
To the solution containing the acrylic prepolymer obtained in Example 1, Coronate L (trimethylolpropane/tolylene diisocyanate trimer adduct, manufactured by Tosoh Corporation) was added per 100 parts of the monomer component used in the preparation of the solution. and 5.2 parts of pigment dispersion 9256BLACK (pigment weight fraction: 20% by weight; manufactured by Tokushiki Co., Ltd.) were added and uniformly mixed to prepare a solvent-type black pressure-sensitive adhesive composition.
(Creating an adhesive sheet)
In the same manner as in Example 1, except that the solvent-based black pressure-sensitive adhesive composition obtained above was used, a photocurable pressure-sensitive adhesive sheet 3 in which a pressure-sensitive adhesive layer having a thickness of about 50 μm was sandwiched between release films was used as a base. It was obtained in the form of a material-less double-sided adhesive sheet.

[Example 4]
(Preparation of prepolymer)
A solution containing an acrylic prepolymer was obtained in the same manner as in Example 1 except that 7.5 parts of cyclohexyl acrylate (CHA) and 12.5 parts of 4-acryloyloxybenzophenone (ABP) were blended.
(Preparation of adhesive composition)
To the solution containing the acrylic prepolymer obtained above, Coronate L (trimethylolpropane/tolylene diisocyanate trimer adduct, manufactured by Tosoh Corporation) is solidified per 100 parts of the monomer component used to prepare the solution. 1 part on a minute basis and 5.2 parts of pigment dispersion 9256BLACK (pigment weight fraction: 20% by weight; manufactured by Tokushiki Co., Ltd.) were added and uniformly mixed to prepare a solvent-type black pressure-sensitive adhesive composition.
(Creating an adhesive sheet)
In the same manner as in Example 1, except that the solvent-based black pressure-sensitive adhesive composition obtained above was used, a photocurable pressure-sensitive adhesive sheet 4 in which a pressure-sensitive adhesive layer having a thickness of about 50 μm was sandwiched between release films was used as a base. It was obtained in the form of a material-less double-sided adhesive sheet.

[Comparative Example 1]
In the same manner as in Example 1, except that 4-acryloyloxybenzophenone (ABP) was not blended, the pressure-sensitive adhesive sheet 5 having a pressure-sensitive adhesive layer having a thickness of about 50 μm sandwiched between release films was used as a substrate-less double-sided pressure-sensitive adhesive sheet. obtained in the form of

[Comparative Example 2]
(Preparation of prepolymer)
100 parts of n-butyl acrylate (BA), 20 parts of cyclohexyl acrylate (CHA), and 2-hydroxyethyl acrylate (2HEA) were added as monomer components to a reaction vessel equipped with a condenser, nitrogen inlet, thermometer and stirrer. 45 parts, 200 parts of ethyl acetate as a polymerization solvent, and 0.5 parts of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator are added to carry out solution polymerization under a nitrogen atmosphere. , to obtain an acrylic polymer solution.

(Preparation of adhesive composition)
To the solution containing the acrylic polymer obtained above, 5 parts of 2-methacryloyloxyethyl isocyanate (MOI) and 0.025 part of dibutyltin dilaurate are added per 100 parts of the monomer component used in preparing the solution, and the mixture is mixed in an air atmosphere. Then, the mixture was stirred at 50° C. for 7 hours to cause addition reaction of MOI to the above polymer to obtain a polymer solution having carbon-carbon double bonds.
To the above polymer solution, 1 part of Coronate L was added on a solid content basis per 100 parts of the polymer in the solution, and the mixture was uniformly mixed to prepare a solvent-based pressure-sensitive adhesive composition.

(Creating an adhesive sheet)
The solvent-based adhesive composition prepared above is applied to the release surface of a 38 μm-thick release film (MRF#38, manufactured by Mitsubishi Plastics, Inc.) in which one side of the polyester film is the release surface, and the solvent-based adhesive composition is applied at 130° C. for 3 minutes. It was dried to form an adhesive sheet with a thickness of 150 µm. The release surface of a release film (manufactured by Mitsubishi Plastics, Inc., MRE #38) with a thickness of 38 μm is attached to this adhesive layer to protect it, and the adhesive layer with a thickness of about 150 μm is photocured sandwiched between the release films. A flexible pressure-sensitive adhesive sheet 6 was obtained in the form of a double-sided pressure-sensitive adhesive sheet without a substrate.

(evaluation)
The following evaluations were performed using the pressure-sensitive adhesive sheets obtained in the above Examples and Comparative Examples. The evaluation method is shown below. The results are shown in Table 1.

[Evaluation of storage modulus]
The shear storage modulus G' before irradiation was evaluated using ARES GII manufactured by TA Instruments. A pressure-sensitive adhesive sheet laminated to a thickness of about 1 mm was punched to φ8 mm, and measured from -50 ° C. to 150 ° C. at an initial strain of 1%, a frequency of 1 Hz, and a heating rate of 10 ° C./min at 25 ° C. and 85 ° C. The shear storage elastic modulus G′ at the time was read and set as the shear storage elastic modulus G′ (G′b25, G′b85) before curing.
The tensile storage modulus E' after irradiation with a high-pressure mercury lamp was evaluated using RSA GII manufactured by TA Instruments. The pressure-sensitive adhesive sheet sandwiched between the release films was irradiated with a high-pressure mercury lamp so that the cumulative amount of light was 3000 mJ/cm ² , and the laminate was laminated to a thickness of about 0.2 mm. Read the tensile storage modulus E' at 25 ° C. and 85 ° C. when measuring from -50 ° C. to 150 ° C. with a length of 20 mm, an initial strain of 0.1%, and a heating rate of 10 ° C./min. was taken as the tensile storage modulus E'(E'a25,E'a85).
This integrated amount of light is a value measured by an industrial UV checker with a peak sensitivity wavelength of about 350 nm (manufactured by Topcon Corporation, trade name: UVR-T1, photodetector model UD-T36).
Regarding the shear storage modulus G′ after UV-LED irradiation, the pressure-sensitive adhesive sheet sandwiched between the release films was irradiated with UV-LED so that the integrated light amount was 800 mJ/cm ² (1 minute), and the thickness was about 1 mm. and punched to a diameter of 8 mm, evaluated in the same manner as before curing, and the shear storage modulus G'(G'a25,G'a85) after UV-LED irradiation.
This integrated amount of light is a value measured by an industrial UV checker with a peak sensitivity wavelength of about 410 nm (manufactured by Topcon, trade name: UVR-T1, light receiving part model UD-T40).
In addition, since the pressure-sensitive adhesive sheet of Comparative Example 1 does not exhibit photocurability, the post-curing storage elastic moduli G' and E' were not evaluated.

[Evaluation of 180° Peel Force]
The 180° peel force was measured according to JIS Z 0237. Specifically, the release film on one side of the pressure-sensitive adhesive sheet sandwiched between the release films was peeled off and attached to a PET substrate (trade name “T912E75 (UE80)”, manufactured by Mitsubishi Chemical Corporation). It was cut into a width of 20 mm, peeled off the other release film, and was attached to an acrylic plate. The sticking method was one reciprocation of a 2 kg roller. 180° peeling was performed 15 minutes or more after application, and the 180° peel strength (N/20 mm) before irradiation was measured. The pulling speed was 300 mm/min.
The 180° peel strength (N/20 mm) after irradiation was evaluated in the same manner as described above after 15 minutes or more from irradiation under the following irradiation conditions.

・High-pressure mercury lamp: Cumulative amount of light 3000 mJ/cm ²
・UV-LED: Cumulative amount of light 4800 mJ/cm ² (6 minutes)

[Evaluation of transmittance]
The release film on one side was peeled off from the pressure-sensitive adhesive sheet, and non-alkali glass was attached to the exposed side. After that, the release film on the other side was peeled off from the adhesive sheet to obtain a sample in which the adhesive sheet was attached to the non-alkali glass plate.
The total light transmittance was measured using a haze meter (manufactured by Murakami Color Science Laboratory, trade name "HN-150") according to the method defined in JIS K7361.

[Evaluation of adhesive residue]
The adherends after the 180° peel force test were visually observed, and those with adhesion of the adhesive were evaluated as "adhesive residue", and those without adhesion were evaluated as "no adhesive residue".

In Examples 1 to 4 and Comparative Example 2, which are photocurable adhesive sheets, the storage elastic modulus increased after irradiation with a high-pressure mercury lamp, the 180° peeling force decreased, no adhesive residue was observed, and reworkability was improved. I can see that it is improving. On the other hand, in Comparative Example 1, which is a pressure-sensitive adhesive sheet that does not exhibit photocurability, adhesive residue is observed, indicating that the reworkability is poor.
In addition, the photocurable pressure-sensitive adhesive sheets of Examples 1 to 4 show little decrease in 180° peeling force after UV-LED irradiation, and curing shrinkage does not progress easily with external light or light from a blue optical semiconductor element. It can be seen that it has excellent light resistance and durability that makes it difficult to peel off from the body. On the other hand, the photocurable pressure-sensitive adhesive sheet of Comparative Example 2 has a significantly reduced 180° peeling force after UV-LED irradiation, and curing shrinkage progresses due to external light and light from blue optical semiconductor elements. It turns out that it becomes easy to exfoliate from the body.

Variations of the present invention are appended below.
[Appendix 1] has a pressure-sensitive adhesive layer that is cured by exposure to radiation,
A photocurable pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer has a 180° peeling force of 11 N/20 mm or less after irradiation with a high-pressure mercury lamp.
[Appendix 2] The photocurable pressure-sensitive adhesive sheet according to Appendix 1, wherein the pressure-sensitive adhesive layer has a rate of change of 180° peel strength before and after UV-LED irradiation of 10% or less.
[Appendix 3] The photocurable pressure-sensitive adhesive sheet according to Appendix 1 or 2, wherein the pressure-sensitive adhesive layer has a tensile storage modulus (E'a25) at 25° C. of 400 kPa or more after irradiation with a high-pressure mercury lamp.
[Appendix 4] The photocurable pressure-sensitive adhesive sheet according to any one of Appendices 1 to 3, wherein the pressure-sensitive adhesive layer has a maximum transmittance of 5% or more at a wavelength of 200 to 400 nm.
[Appendix 5] The adhesive layer has a ratio (kPa/μm) of a tensile storage modulus (E′a25: kPa) at 25° C. after irradiation with a high-pressure mercury lamp to a thickness (μm) of 1 to 50. The photocurable pressure-sensitive adhesive sheet according to any one of 1 to 4.
[Appendix 6] The photocurable pressure-sensitive adhesive sheet according to any one of Appendices 1 to 5, wherein the light irradiated by the high-pressure mercury lamp includes radiation having a wavelength of 200 to 280 nm.
[Appendix 7] The photocurable pressure-sensitive adhesive sheet according to any one of Appendices 2 to 6, wherein the light irradiated by the UV-LED is radiation having a wavelength of 350 nm or more.
[Appendix 8] A substrate, one or more optical semiconductor elements arranged on the substrate, and the photocurable adhesive sheet according to any one of Appendices 1 to 7,
An optical semiconductor device, wherein the photocurable adhesive sheet seals the optical semiconductor element.
[Appendix 9] The optical semiconductor device according to Appendix 8, which is a self-luminous display device.
[Appendix 10] An image display device comprising the self-luminous display device according to Appendix 9.
[Appendix 11] A method for removing the photocurable adhesive sheet from the substrate of the optical semiconductor device according to any one of appendices 8 to 10 and one or more optical semiconductor elements arranged on the substrate. hand,
A step of irradiating the photocurable adhesive sheet with radiation containing light having a wavelength of 200 to 280 nm, and removing the cured photocurable adhesive sheet from the substrate and one or more optical semiconductor elements arranged on the substrate. A peeling method, comprising a step of peeling.
[Appendix 12] The peeling method according to appendix 11, wherein the radiation containing light having a wavelength of 200 to 280 nm is radiation from a high-pressure mercury lamp.

10 Photocurable Adhesive Sheet 1 Adhesive Layers S1, S2 Release Film 11 Photocurable Adhesive Sheet S3 Base Material S4 Release Film 20 Self Emitting Display Device (Mini/Micro LED Display Device)
2 substrate 3 metal wiring layer 4 optical semiconductor element (LED chip)
S5 base material (cover member)

Claims (12)

having an adhesive layer that cures when exposed to radiation;
A photocurable pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer has a 180° peeling force of 11 N/20 mm or less after irradiation with a high-pressure mercury lamp. 2. The photocurable pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a rate of change of 180° peel strength before and after UV-LED irradiation of 10% or less. The photocurable pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a tensile storage modulus (E'a25) at 25°C after irradiation with a high-pressure mercury lamp of 400 kPa or more. The photocurable pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a maximum transmittance of 5% or more at a wavelength of 200 to 400 nm. Claims 1 to 4, wherein the pressure-sensitive adhesive layer has a ratio (kPa/μm) of a tensile storage modulus (E'a25: kPa) at 25°C after irradiation with a high-pressure mercury lamp to a thickness (μm) of 1 to 50. The photocurable pressure-sensitive adhesive sheet according to any one of the above. The photocurable pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the light irradiated by the high-pressure mercury lamp contains radiation with a wavelength of 200 to 280 nm. The photocurable pressure-sensitive adhesive sheet according to any one of claims 2 to 6, wherein the light emitted from the UV-LED is radiation having a wavelength of 350 nm or longer. A substrate, one or more optical semiconductor elements arranged on the substrate, and the photocurable adhesive sheet according to any one of claims 1 to 7,
An optical semiconductor device, wherein the photocurable adhesive sheet seals the optical semiconductor element. 9. The optical semiconductor device according to claim 8, which is a self-luminous display device. An image display device comprising the self-luminous display device according to claim 9 . A method of peeling the photocurable adhesive sheet from the substrate of the optical semiconductor device according to any one of claims 8 to 10 and one or more optical semiconductor elements arranged on the substrate,
A step of irradiating the photocurable adhesive sheet with radiation containing light having a wavelength of 200 to 280 nm, and removing the cured photocurable adhesive sheet from the substrate and one or more optical semiconductor elements arranged on the substrate. A peeling method, comprising a step of peeling. 12. The peeling method according to claim 11, wherein the radiation containing light with a wavelength of 200 to 280 nm is radiation from a high-pressure mercury lamp.

Images