JP2017002260A - Adhesive sheet for picture display unit, manufacturing method of picture display unit and picture display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet for picture display unit having an adhesive layer excellent in followability to step part formed on an adherend as well as transparency after standing under high temperature high humidity environment and air bubble resistance.SOLUTION: There is provided an adhesive sheet for picture display unit 1 formed from an adhesive resin composition containing (A) a (meth)acrylic acid-based derivative polymer having a film-like adhesive layer 2, a pair of substrate layers 3 and 4 laminated with sandwiching the adhesive layer 2, containing a structural unit derived from alkyl (meth)acrylate with an alkyl group having 4 to 18 carbon atoms and having weight average molecular weight of 250,000 to 500,000, (B) a (meth)acrylic acid-based derivative monomer having a (meth)acryloyl group in a molecule, (C) a crosslinking agent having bi- or higher functional (meth)acryloyl group and (D) a photoinitiator.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an adhesive sheet for an image display device, a method for manufacturing the image display device, and an image display device.

  In recent years, a gap between a transparent protective plate or an information input device (for example, a touch panel) in an image display device and a display surface of an image display unit or a gap between a transparent protective plate and an information input device is compared with air. A method has been proposed in which the refractive index is replaced with a transparent material close to the display surface of the transparent protective plate, the information input device, and the image display unit, thereby improving the transparency and suppressing the decrease in luminance and contrast of the image display device. (For example, Patent Document 1). A schematic example of a liquid crystal display device is shown in FIG. 1 as an example of an image display device. The liquid crystal display device with a built-in touch panel is composed of a transparent protective plate (glass or plastic substrate) D1, a touch panel D2, a polarizing plate D3, and a liquid crystal display cell D4. In addition, in order to improve visibility, an adhesive layer D5 may be provided between the transparent protective plate D1 and the touch panel D2, and an adhesive layer D6 may be further provided between the touch panel D2 and the polarizing plate D3.

  By the way, in the information input device and the image display unit, it is necessary to provide input / output wiring at the peripheral portion thereof, and in general, at the peripheral portion of the transparent protective plate so that these wirings cannot be seen from the transparent protective plate surface side. A frame-shaped decorative portion is provided by printing or the like (19 (frame pattern) in FIG. 1A of Patent Document 1). In order to eliminate the level difference caused by these decorative parts, for example, a film-like pressure-sensitive adhesive may be used as the pressure-sensitive adhesive that bonds the transparent protective plate. An excellent step embedding property is required for an adhesive. In recent years, various film-like pressure-sensitive adhesives for improving the step embedding property have been studied (for example, Patent Document 2 and Patent Document 3).

JP 2008-83491 A JP 2010-163591 A International Publication No. 2012/0777806

In recent years, for the purpose of reducing the thickness of a terminal, studies have been made to add a touch panel function to a transparent protective plate called a cover glass integrated touch panel or one glass solution (OGS). In this case, since the transparent protective plate with a touch panel function and the image display unit are bonded together with an adhesive, not only the step and wiring formed on the transparent protective plate with a touch panel function are embedded without bubbles but also to both adherends. The reliability of adhesive strength is an issue.
In addition, with the expansion of the use of the image display device in the global market, for example, in order to prevent the visibility of the image display device from being deteriorated even under high temperature and high humidity conditions such as use in a high temperature and high humidity region, "Bubble resistance" that does not occur and prevention of whitening of the adhesive sheet are required.
The present invention has been made in view of the above circumstances, and even when the level difference formed on the adherend is high, it has excellent followability to the level difference, transparency after being left in a high-temperature and high-humidity environment, and It aims at providing the adhesive sheet for image display apparatuses provided with the adhesive layer excellent in bubble resistance. Another object of the present invention is to provide an image display device manufacturing method and an image display device using the pressure-sensitive adhesive sheet for the image display device.

  As a result of diligent research to solve the above problems, the present inventors have a weight average molecular weight of 250,000 to 500,000 including a structural unit derived from an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms. (Meth) acrylic acid derivative polymer, (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule, bifunctional or higher functional (meth) acryloyl group crosslinking agent, and photopolymerization initiator It has been found that the above-mentioned problems can be solved if the pressure-sensitive adhesive sheet is formed from a pressure-sensitive adhesive resin composition containing a specific property and has specific physical properties. The present invention has been completed based on such findings.

  That is, this invention is equipped with the adhesion layer and a pair of base material layer laminated | stacked so that the adhesion layer may be pinched | interposed, and an adhesion layer is C1-C18 alkyl (meta) whose carbon number is an alkyl group. (Meth) acrylic acid derivative polymer (A) having a weight average molecular weight of 250,000 to 500,000 including a structural unit derived from acrylate, and a (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule (B) Provided is a pressure-sensitive adhesive sheet for an image display device formed from a pressure-sensitive resin composition containing a crosslinking agent (C) having a bi- or higher functional (meth) acryloyl group and a photopolymerization initiator (D).

  The pressure-sensitive adhesive sheet for an image display device may include a first and second base material layer laminated so as to sandwich the pressure-sensitive adhesive layer, and a carrier layer further laminated on the second base material layer.

  The pressure-sensitive adhesive layer provided in the pressure-sensitive adhesive sheet for an image display device may contain stearyl (meth) acrylate as the (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule. Thereby, it becomes what was excellent in adhesiveness, transparency, fluidity | liquidity, and a dielectric constant.

  The thickness of the pressure-sensitive adhesive layer in these pressure-sensitive adhesive sheets for image display devices is preferably 50 to 500 μm. Thereby, it becomes excellent in impact resistance and visibility.

  The present invention further includes a step of bonding the adherends to each other via an adhesive layer provided in the adhesive sheet for an image display device to obtain a laminate, and the laminate is obtained at 30 to 80 ° C. and 0.3 to 0.8 MPa. And a process of heating and pressurizing under the conditions described above.

  According to such a method for manufacturing an image display device, an image display device in which a decrease in visibility is suppressed can be manufactured by using the pressure-sensitive adhesive sheet for an image display device according to an embodiment of the present invention. By using an adhesive sheet for an image display device according to an embodiment of the present invention, for example, an image display unit such as a liquid crystal display cell and a transparent protective plate with a touch panel function, the image display unit and a touch panel, the image display unit and a transparent Members (such as optical members) required for the image display unit and other image display devices such as a protective plate, a touch panel, and a transparent protective plate can be bonded together. The manufacturing method according to an embodiment of the present invention is particularly useful when the adherend is an image display unit and a transparent protective plate with a touch panel function. Similarly, by using the pressure-sensitive adhesive sheet for an image display device according to an embodiment of the present invention, members on the viewing side of the image display unit of the image display device can be bonded together. In that case, for example, even if the transparent protective plate on the viewing side has a high step along the outer periphery, it is presumed that the adhesive layer can surely embed the step, so that the visibility is not lowered. The

The present invention is also the image display unit, the transparent protective plate, the adhesive layer or the cured product thereof provided in the pressure-sensitive adhesive sheet for an image display device according to the present invention, which is interposed between the image display unit and the transparent protective plate. An image display device comprising a certain transparent resin layer is provided.
The present invention also provides an image display unit, a transparent protective plate with a touch panel function, and the adhesive sheet for an image display device according to the present invention, which is interposed between the image display unit and the transparent protective plate with a touch panel function. Provided is an image display device comprising the above-mentioned pressure-sensitive adhesive layer or a transparent resin layer that is a cured product thereof.
Since the adhesive layer has excellent followability to high steps, an image having excellent impact resistance and visibility even when a high step is provided on the image display unit, touch panel or transparent protective plate. A display device can be obtained.

  According to the present invention, even if the step formed on the adherend is high, the pressure-sensitive adhesive layer has excellent followability to the step, transparency after being left in a high-temperature and high-humidity environment, and excellent bubble resistance. An adhesive sheet for an image display device can be provided. Moreover, according to this invention, the manufacturing method and image display apparatus of an image display apparatus using such an adhesive sheet can be provided.

It is sectional drawing which shows an example of the conventional image display apparatus. It is a perspective view which shows one Embodiment of the adhesive sheet for image display apparatuses which concerns on this invention. It is sectional drawing which shows one Embodiment of the adhesive sheet for image display apparatuses which concerns on this invention. It is sectional drawing of a base material film. It is sectional drawing which shows a cutting process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a sticking process. It is sectional drawing which shows one Embodiment of the image display apparatus which concerns on this invention. It is sectional drawing which shows one Embodiment of the image display apparatus which concerns on this invention. It is sectional drawing which shows the peeling process of a light peeling separator. It is sectional drawing which shows the sticking process of the adhesion surface to a to-be-adhered body. It is sectional drawing which shows the peeling process of a heavy peeling separator. It is sectional drawing which shows the sticking process of the adhesion surface to a to-be-adhered body. It is a perspective view which shows one Embodiment of the adhesive sheet for image display apparatuses which concerns on this invention. It is a side view which shows one Embodiment of the adhesive sheet for image display apparatuses which concerns on this invention. It is sectional drawing of a base material film. It is sectional drawing which shows a cutting process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a sticking process. It is sectional drawing which shows the peeling process of a carrier film. It is a schematic diagram which shows the sample measuring method using a wide area dynamic viscoelasticity measuring apparatus.

Hereinafter, preferred embodiments (first embodiment and second embodiment) of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, the description which overlaps with both embodiment shall be demonstrated only in 1st embodiment, and description is abbreviate | omitted suitably in description of 2nd embodiment. In the present specification, “(meth) acrylate” means “acrylate” or “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” or “methacryl” corresponding thereto, and “(meth) acryloyl” means “acryloyl” or “methacryloyl” corresponding thereto. The “adhesive sheet for an image display device” may be simply referred to as “adhesive sheet”.

[First embodiment]
<Adhesive sheet for image display device>
The pressure-sensitive adhesive sheet for an image display device according to the present embodiment includes a pressure-sensitive adhesive layer and a pair of base material layers laminated so as to sandwich the pressure-sensitive adhesive layer. It is preferable that the outer edge of the base material layer projects outward from the outer edge of the adhesive layer.

  That is, as shown in FIG. 2 and FIG. 3, the pressure-sensitive adhesive sheet 1 according to this embodiment includes a transparent film-like pressure-sensitive adhesive layer 2, a heavy release separator 3 (one base material) sandwiching the pressure-sensitive adhesive layer 2, and a light And a release separator 4 (the other substrate). The adhesive layer 2 is, for example, a transparent film disposed between the transparent protective plate 40 and the touch panel 30 or between the touch panel 30 and the liquid crystal display unit in an image display device such as a touch panel display for a portable terminal. It is.

  The pressure-sensitive adhesive layer 2 is a (meth) acrylic acid derivative polymer (A) having a weight average molecular weight of 250,000 to 500,000 including a structural unit derived from an alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group. Hereinafter, also referred to as “component (A)”), (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule (hereinafter also referred to as “component (B)”), Crosslinking agent (C) having a bifunctional or higher functional (meth) acryloyl group (hereinafter also referred to as “component (C)”), photopolymerization initiator (D) (hereinafter also referred to as “component (D)”) It is formed from the adhesive resin composition containing this.

  The adhesive layer 2 preferably has the following physical properties. That is, since the adhesive layer 2 is used for an image display device, the haze needs to be 1.5% or less. From the viewpoint of visibility, the haze is preferably 1.0% or less, more preferably 0.8% or less, and still more preferably 0.5% or less. The lower limit of haze is preferably close to 0%, but is usually larger than 0% and 0.1% or more from a practical viewpoint.

  Haze depends on the compatibility between the (A) component, (B) component, (C) component, and (D) component described later. If the compatibility between the component (A), the component (B), the component (C), and the component (D) is good, the haze can be lowered.

  Haze is a value (%) representing turbidity. From the total transmittance T of light irradiated by a lamp and transmitted through a sample, and the transmittance D of light diffused and scattered in the sample, It is calculated as (D / T) × 100. These are defined by JIS K 7136, and can be easily measured by a commercially available turbidimeter, for example, Nippon Denshoku Industries Co., Ltd., trade name: NDH-5000.

  The adhesive layer 2 preferably has a tan δ at 25 ° C. in the range of 0.8 to 2.0. When tan δ at 25 ° C. is 0.8 or more, the step following ability tends to be further improved. On the other hand, when tan δ at 25 ° C. is 2.0 or less, the film formability tends to be good. From the above viewpoint, tan δ at 25 ° C. is more preferably in the range of 0.8 to 2.0, and still more preferably in the range of 0.8 to 1.5.

  Here, tan δ is a value obtained by dividing the shear loss elastic modulus by the shear storage elastic modulus, and the shear loss elastic modulus and the shear storage elastic modulus are values measured by a wide area dynamic viscoelasticity measuring apparatus. Specifically, the shear loss modulus and the shear storage modulus are measured by the following methods.

(Measurement of shear loss modulus and shear storage modulus)
A shear loss elastic modulus and a shear storage elastic modulus were prepared by preparing a pressure-sensitive adhesive layer having a thickness of 0.5 mm, a width of 10 mm, and a length of 10 mm, and a wide-range dynamic viscoelasticity measuring apparatus (manufactured by Rheometric Scientific, trade name: Solid Analyzer RSA). -III) can be measured under the conditions “share sandwich mode, frequency 1.0 Hz, measurement temperature range −20 to 100 ° C., temperature rising rate 5 ° C./min”.

  Although the thickness of the adhesion layer 2 is not specifically limited since it is suitably adjusted with a use use and a method, 50-500 micrometers is preferable, 100-350 micrometers is more preferable, 125-300 micrometers is still more preferable. When used in this range, it exhibits particularly excellent effects as a transparent adhesive sheet for laminating an optical member on a display.

The pressure-sensitive adhesive layer 2 has, for example, a weight average molecular weight of 250,000 to 500,000 including a structural unit derived from an alkyl (meth) acrylate having 4 to 18 carbon atoms on the heavy release separator 3. A (meth) acrylic acid derivative polymer, a (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule, a cross-linking agent having a bifunctional or higher (meth) acryloyl group, and a photopolymerization initiator It is formed by coating the contained adhesive resin composition at an arbitrary thickness, irradiating the active energy ray on this to cure, and then cutting it into a desired size. As the light source of the active energy ray, a light source having a light emission distribution at a wavelength of 400 nm or less is preferable. Can be used. Although the irradiation energy is not particularly limited, it is preferably 800~2000mJ / cm ^2, more preferably 900~1500mJ / cm ^2, further preferably 1000~1200mJ / cm ^2.
The adhesive resin composition comprises (meth) acrylic acid derivative polymer (A), (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule, ) A crosslinking agent (C) having an acryloyl group and a photopolymerization initiator (D) are contained.
Hereinafter, the adhesive resin composition will be described.

[(A) component: (meth) acrylic acid derivative polymer (A)]
The (meth) acrylic acid derivative polymer (A) refers to a polymer obtained by polymerizing one type of monomer having one (meth) acryloyl group in the molecule or copolymerizing two or more types. In addition, if it is a range which does not impair the effect of this embodiment, (A) component is a compound which has 2 or more of (meth) acryloyl groups in a molecule | numerator, or a polymerizable compound which does not have a (meth) acryloyl group (A compound having one polymerizable unsaturated bond in the molecule such as acrylonitrile, styrene, vinyl acetate, ethylene, propylene, a compound having two or more polymerizable unsaturated bonds in the molecule such as divinylbenzene) ) Copolymerized with an acrylic acid derivative polymer.

  (A) Monomers having one (meth) acryloyl group in the molecule forming the component include, for example, (meth) acrylic acid; (meth) acrylic acid amide; (meth) acryloylmorpholine; methyl (meth) acrylate , Ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) ) Acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate (n-lauryl (meth) acrylate), carbon number of alkyl groups such as stearyl (meth) acrylate 1-18 alkyl ( ) Acrylate; (meth) acrylate having an aromatic ring such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate; fat such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylate (Meth) acrylate having a cyclic group; tetrahydrofurfuryl (meth) acrylate; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethyl (meth) (Meth) acrylamide derivatives such as acrylamide, N-isopropyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide; 2- (2-methacryloyloxyethyloxy) ester Le isocyanate, 2- (meth) acrylate having an isocyanate group of acryloyloxyethyl isocyanate (meth) acrylate, alkylene glycol chain-containing (meth) acrylate.

The component (A) preferably contains an alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group represented by the following formula (a) among the above compounds, and has 6 to 12 carbon atoms. (Meth) acrylate having an alkyl group is more preferred. Moreover, it is preferable that the content rate of such (meth) acrylate is 50-90 mass% with respect to the copolymerized polymer total mass, It is more preferable that it is 60-80 mass%, 65- More preferably, it is 75 mass%. When the content ratio of (meth) acrylate represented by the following formula (a) is in such a range, the workability of the formed adhesive layer is improved, and the adhesive layer and a transparent protective plate (glass substrate, plastic substrate, etc.) ) Is also improved. In general, a polymer having such a copolymerization ratio can be obtained by blending each monomer in the same ratio as the above-mentioned copolymerization ratio and copolymerizing them. The polymerization rate is more preferably substantially close to 100% by mass.
CH ₂ = CXCOOR (a)
In formula (a), X represents a hydrogen atom or a methyl group, and R represents an alkyl group having 4 to 18 carbon atoms.

  Examples of the alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group include n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, and n-octyl (meth) acrylate. , Isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, etc., among which n-butyl (meth) acrylate, isooctyl (meth) acrylate, 2- Ethylhexyl (meth) acrylate and n-octyl (meth) acrylate are preferable, and 2-ethylhexyl (meth) acrylate is more preferable. Further, alkyl acrylate is more preferable than alkyl methacrylate. These alkyl (meth) acrylates may be used in combination of two or more.

  Other monomers copolymerized with an alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group are not limited to those described above, but include a hydroxyl group, a morpholino group, an amino group, a carboxyl group, a cyano group, A monomer having a polar group such as a group derived from a carbonyl group, a nitro group or an alkylene glycol is preferred. The (meth) acrylate having these polar groups improves the adhesiveness between the adhesive layer and the transparent protective plate.

In particular, it is preferable to use together an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms and an alkylene glycol chain-containing (meth) acrylate represented by the following formula (b).
CH ₂ = CXCOO (C _p H _2p O) _q R (b)
In formula (b), X represents a hydrogen atom or a methyl group, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, p represents an integer of 2 to 4, and q represents an integer of 1 to 10. Show.

  Examples of the alkylene glycol chain-containing (meth) acrylate represented by the formula (b) include 2-hydroxyethyl (meth) acrylate, 1-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl. (Meth) acrylate, 1-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 1-hydroxybutyl (meth) acrylate, etc. Hydroxyl group-containing (meth) acrylates; diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, hexaethylene glycol mono ( Polyethylene glycol mono (meth) acrylates such as acrylate); Polypropylene glycol mono (meth) acrylates such as dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate, octapropylene glycol mono (meth) acrylate; Polybutylene glycol mono (meth) acrylates such as butylene glycol mono (meth) acrylate and tributylene glycol mono (meth) acrylate; methoxytriethylene glycol (meth) acrylate, methoxytetraethylene glycol (meth) acrylate, methoxyhexaethylene glycol ( (Meth) acrylate, methoxyoctaethylene glycol (meth) acrylate, methoxynonaethylene glycol (meth) Alkoxypolyalkylene glycols such as acrylate, methoxypolyethylene glycol (meth) acrylate, methoxyheptapropylene glycol (meth) acrylate, ethoxytetraethylene glycol (meth) acrylate, butoxyethylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate ) Acrylate and the like. Among these, 2-hydroxyethyl (meth) acrylate, 1-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 4 -Hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 1-hydroxybutyl (meth) acrylate are preferred, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate is more preferable, and 2-hydroxyethyl (meth) acrylate is more preferable. These alkylene glycol chain-containing (meth) acrylates may be used in combination of two or more.

  (A) It is preferable that the value converted into the weight average molecular weight of the component using the standard polystyrene calibration curve by gel permeation chromatography (GPC) is 250,000-500,000. When the weight average molecular weight is 250,000 or more, an adhesive layer having an adhesive force that is less likely to be peeled off from a transparent protective plate or the like can be obtained, and when it is 500,000 or less, an adhesive resin is obtained. The viscosity of the composition does not become too high, and the processability when making a sheet-like adhesive layer becomes better. From the above viewpoint, the weight average molecular weight of the component (A) is preferably 250,000 to 500,000, and more preferably 300,000 to 500,000.

  As the polymerization method for component (A), known polymerization methods such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization and the like can be used.

  As the polymerization initiator for polymerizing the component (A), a compound that generates a radical by heat can be used. Specifically, organic peroxides such as benzoyl peroxide and lauroyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), etc. Azo compounds.

  The content of the component (A) is preferably 15 to 80% by mass, more preferably 15 to 60% by mass, and more preferably 15 to 50% by mass with respect to the total mass of the adhesive resin composition. Further preferred. When the content of the component (A) is 15 to 80% by mass, the viscosity of the pressure-sensitive adhesive resin composition falls within an appropriate viscosity range for producing the pressure-sensitive adhesive layer, and the workability becomes better. Moreover, the obtained adhesive layer has good adhesiveness to a transparent protective plate such as a glass substrate or a plastic substrate.

[(B) component: (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule]
The (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule is exemplified as a monomer having one (meth) acryloyl group forming the component (A) in the molecule. The thing similar to a compound is mentioned.

  In addition, in this embodiment, it is preferable that (B) component contains a stearyl (meth) acrylate from a viewpoint of adhesiveness, transparency, fluidity | liquidity, and a dielectric constant. Moreover, it is preferable that (B) component contains (meth) acryloyl morpholine from a viewpoint of adhesiveness, transparency, and handleability.

  Examples of stearyl (meth) acrylate include n-stearyl (meth) acrylate (also referred to as octadecyl (meth) acrylate), isostearyl (meth) acrylate (also referred to as 16-methylheptadecyl (meth) acrylate), and the like. Among these, isostearyl (meth) acrylate is more preferable. These stearyl (meth) acrylates may be used in combination of two or more.

  The content of stearyl (meth) acrylate is preferably 1 to 7% by mass, more preferably 2 to 6% by mass, and still more preferably 3 to 5% by mass with respect to the total mass of the adhesive resin composition. When the content of the N-substituted maleimide is in the range of 1 to 7% by mass, the tensile shear adhesive force at 85 ° C. between the adhesive layer obtained from the adhesive resin composition and the adherend becomes higher.

  (B) As for content of a component, 15-80 mass% is preferable with respect to the total mass of an adhesive resin composition. When the content of the component (B) is in the range of 15 to 80% by mass, the viscosity of the pressure-sensitive adhesive resin composition falls within an appropriate viscosity range for producing the pressure-sensitive adhesive layer, and the workability becomes better. Moreover, it will become more excellent also in the adhesiveness and transparency of the obtained adhesive sheet. And the obtained adhesion layer becomes a thing excellent also in level | step difference embedding property. From the above viewpoint, the content of the component (B) is more preferably 30 to 80% by mass, and further preferably 40 to 80% by mass.

[Component (C): Crosslinker (C) having a bifunctional or higher (meth) acryloyl group]
(C) As a specific example of a component, the compound represented by following formula (c)-(h) is illustrated suitably. However, in formulas (c), (d) and (e), s represents an integer of 1 to 20, and in formulas (f) and (g), m and n each independently represents an integer of 1 to 10. Show.

  Urethane di (meth) acrylate having a urethane bond can also be used as the component (C).

  The urethane di (meth) acrylate having a urethane bond preferably has a polyalkylene glycol chain from the viewpoint of good compatibility with other components. Moreover, it is preferable to have an alicyclic structure from a viewpoint of ensuring transparency. When the compatibility between the component (C), the component (A) and the component (B) is low, the cured product may become cloudy.

  The component (C) has a weight average molecular weight of preferably 100,000 or less, more preferably 300 to 100,000, from the viewpoint of further suppressing generation of bubbles and peeling under high temperature or high temperature and high humidity. More preferably, it is 500-80,000.

  It is preferable that content of (C) component is 15 mass% or less with respect to the total mass of an adhesive resin composition. When the content is 15% by mass or less, since the crosslinking density does not become too high, an adhesive layer having more sufficient adhesiveness, high elasticity, and no brittleness can be obtained. Further, from the viewpoint of further improving the level difference embedding property, the content of the component (C) is more preferably 10% by mass or less, and further preferably 7% by mass or less.

  Although there is no restriction | limiting in particular about the minimum of content of (C) component, From a viewpoint which makes film-forming property more favorable, it is preferable that it is 0.1 mass% or more, and it is more preferable that it is 2 mass% or more. More preferably, it is 3 mass% or more.

[(D) component: photopolymerization initiator (D)]
(D) A component accelerates | stimulates hardening reaction by irradiation of an active energy ray. Here, active energy rays refer to ultraviolet rays, electron beams, α rays, β rays, γ rays and the like.

  The component (D) is not particularly limited, and known materials such as benzophenone, anthraquinone, benzoyl, sulfonium salt, diazonium salt, onium salt and the like can be used.

  Specifically, benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4,4′-dimethyl Aminobenzophenone, α-hydroxyisobutylphenone, 2-ethylanthraquinone, t-butylanthraquinone, 1,4-dimethylanthraquinone, 1-chloroanthraquinone, 2,3-dichloroanthraquinone, 3-chloro-2-methylanthraquinone, 1,2 -Benzoanthraquinone, 2-phenylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane − Aromatic ketone compounds such as 1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 2,2-diethoxyacetophenone; Benzoin compounds such as benzoin, methylbenzoin and ethylbenzoin; Benzoin methyl ether Benzoin ether compounds such as benzoin ethyl ether, benzoin isobutyl ether and benzoin phenyl ether; benzyl compounds such as benzyl and benzyldimethyl ketal; ester compounds such as β- (acridin-9-yl) (meth) acrylic acid; 9-phenyl Acridine compounds such as acridine, 9-pyridylacridine, 1,7-diacridinoheptane; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5- Di (m-metoki Phenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p- Methoxyphenyl) -4,5-diphenylimidazole dimer, 2,4-di (p-methoxyphenyl) 5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole Dimer, 2,4,5-triarylimidazole dimer such as 2- (p-methylmercaptophenyl) -4,5-diphenylimidazole dimer; 2-benzyl-2-dimethylamino-1- ( 4-morpholinophenyl) -1-butanone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propane; bis (2,4 , 6-trimethylbenzoyl) -phenylphosphine oxide; oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone) and the like. These compounds may be used in combination.

  Particularly, as the component (D) that does not color the adhesive resin composition, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- ( Α-hydroxyalkylphenone compounds such as 2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one; bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide Acylphosphine oxide compounds such as bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; Hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propyl Pannon), and the like, is preferable, particularly combinations thereof.

  In order to produce a particularly thick sheet (adhesive layer), the component (D) contains bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2. , 4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and the like are preferably included.

  The content of the component (D) in this embodiment is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass with respect to the total mass of the adhesive resin composition, and 0 More preferably, it is 1 to 0.5% by mass. By setting the content of the component (D) to 5% by mass or less, it is possible to obtain a pressure-sensitive adhesive layer that has a high transmittance and does not have a yellowish hue.

[Other ingredients]
In addition to the above components (A), (B), (C), and (D), the adhesive resin composition may contain various additives as necessary. Examples of the various additives include polymerization inhibitors such as p-methoxyphenol added for the purpose of enhancing the storage stability of the adhesive resin composition, and heat resistance of the adhesive layer obtained by photocuring the adhesive resin composition. Antioxidants such as triphenyl phosphite added for the purpose of enhancing the properties, light stabilizers such as HALS (Hindered Amine Light Stabilizer) added for the purpose of enhancing the resistance of the adhesive resin composition to light such as ultraviolet rays, and glass Examples thereof include a silane coupling agent to be added in order to improve the adhesion of the adhesive resin composition to the above.

  In particular, the addition of a silane coupling agent is preferable because the decrease in adhesive force is suppressed even when exposed to high temperature and high humidity. Examples of such silane coupling agents include vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-methacryloxypropylmethyl. Diethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-aminopropyltriethoxysilane can be suitably used.

  The amount of the silane coupling agent added is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more. Moreover, it is preferable that it is 5 mass% or less, it is more preferable that it is 2 mass% or less, and it is still more preferable that it is 1 mass% or less. When the content of the silane coupling agent is within this range, the obtained adhesive layer has better adhesiveness after exposure to high temperature and high humidity.

  In addition, when obtaining the adhesive sheet for image display apparatuses, the adhesive layer is sandwiched between the base material (heavy release separator 3) of a polymer film such as a polyethylene terephthalate film and the cover film (light release separator 4) of the same material. Become. At this time, in order to control the peelability between the adhesive layer and the base material such as polyethylene terephthalate film and the cover film, the adhesive resin composition contains a surfactant such as polydimethylsiloxane or fluorine. It can be included.

These additives may be used alone or in combination with a plurality of additives. In addition, the content of these other additives is usually small compared with the total content of the above (A), (B), and (C), and generally the total mass of the adhesive resin composition. On the other hand, it is about 0.01-5 mass%.
The light transmittance of the adhesive layer for light in the visible light region (wavelength: 380 to 780 nm) is preferably 80% or more, preferably 90% or more, and more preferably 95% or more. .

  As the heavy release separator 3, for example, a polymer film such as polyethylene terephthalate, polypropylene, polyethylene, or polyester is preferable, and among them, a polyethylene terephthalate film (hereinafter sometimes referred to as “PET film”) is more preferable. From the viewpoint of workability, the thickness of the heavy release separator 3 is preferably 50 μm or more and 200 μm or less, more preferably 60 μm or more and 150 μm or less, and further preferably 70 μm or more and 130 μm or less. The plane shape of the heavy release separator 3 is larger than the plane shape of the pressure sensitive adhesive layer 2 from the viewpoint of protecting the outer edge of the pressure sensitive adhesive layer, ease of handling, ease of peeling, and reducing adhesion of dust and the like. The outer edge of the adhesive layer 2 preferably projects outward from the outer edge of the adhesive layer 2. The width at which the outer edge of the heavy release separator 3 protrudes from the outer edge of the adhesive layer 2 is 2 mm or more and 20 mm or less from the viewpoint of protecting the outer edge of the adhesive layer, ease of handling, ease of peeling, and reducing adhesion of dust and the like. It is preferable that it is 4 mm or more and 10 mm or less. When the planar shape of the pressure-sensitive adhesive layer 2 and the heavy release separator 3 is a substantially rectangular shape such as a substantially rectangular shape, the width at which the outer edge of the heavy release separator 3 projects beyond the outer edge of the pressure-sensitive adhesive layer 2 is 2 mm at least on one side. It is preferably 20 mm or less, more preferably 4 mm or more and 10 mm or less on at least one side, more preferably 2 mm or more and 20 mm or less on all sides, and 4 mm or more and 10 mm or less on all sides. It is particularly preferred.

  As the light release separator 4, for example, a polymer film such as polyethylene terephthalate, polypropylene, polyethylene, and polyester is preferable, and among them, a polyethylene terephthalate film is more preferable. From the viewpoint of workability, the thickness of the light release separator 4 is preferably 25 μm or more and 150 μm or less, more preferably 30 μm or more and 100 μm or less, and further preferably 40 μm or more and 75 μm or less. The plane shape of the light release separator 4 is larger than the plane shape of the pressure sensitive adhesive layer 2 from the viewpoint of protecting the outer edge of the pressure sensitive adhesive layer, ease of handling, ease of peeling, and reducing adhesion of dust and the like. The outer edge of the adhesive layer 2 preferably projects outward from the outer edge of the adhesive layer 2. The width at which the outer edge of the light release separator 4 projects beyond the outer edge of the adhesive layer 2 is 2 mm or more and 20 mm or less from the viewpoint of protecting the outer edge of the adhesive layer, ease of handling, ease of peeling, and reducing adhesion of dust and the like. It is preferable that it is 4 mm or more and 10 mm or less. When the planar shape of the pressure-sensitive adhesive layer 2 and the light release separator 4 is a substantially rectangular shape such as a substantially rectangular shape, the width at which the outer edge of the light release separator 4 protrudes from the outer edge of the pressure-sensitive adhesive layer 2 is 2 mm on at least one side. It is preferably 20 mm or less, more preferably 4 mm or more and 10 mm or less on at least one side, more preferably 2 mm or more and 20 mm or less on all sides, and 4 mm or more and 10 mm or less on all sides. It is particularly preferred.

  The peel strength between the light release separator 4 and the adhesive layer 2 is preferably lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. Thereby, the heavy release separator 3 is less likely to peel from the adhesive layer 2 than the light release separator 4. Further, as will be described later, since the blade B is passed through the adhesive layer 2 toward the heavy release separator 3, the outer edge portion of the adhesive layer 2 is pressed against the heavy release separator 3. Thereby, the heavy release separator 3 becomes more difficult to peel from the adhesive layer 2 than the light release separator 4, and the light release separator 4 can be released before the heavy release separator 3 is peeled off. Therefore, the separators 3 and 4 can be peeled one by one, and the work of peeling the separators 3 and 4 and sticking the adhesive layer 2 to separate adherends can be reliably performed one by one. The peel strength between the heavy release separator 3 and the pressure-sensitive adhesive layer 2 and between the light release separator 4 and the pressure-sensitive adhesive layer 2 can be adjusted, for example, by subjecting the heavy release separator 3 and the light release separator 4 to surface treatment. Examples of the surface treatment method include a mold release treatment with a silicone compound or a fluorine compound.

<Method for producing pressure-sensitive adhesive sheet for image display device>
The adhesive sheet 1 demonstrated above is manufactured as follows. First, as shown in FIG. 4, a base material film 10 in which the adhesive layer 2 is formed on the heavy release separator 3 and the temporary separator 6 is formed on the adhesive layer 2 is prepared. The temporary separator 6 is, for example, a layer made of the same material as the light release separator 4.

  Subsequently, as shown in FIG. 5, the temporary separator 6 and the adhesive layer 2 are cut into desired shapes by a punching device (not shown) provided with a blade B. The punching device may be a crank punching device, a reciprocating punching device, or a rotary punching device. Moreover, a laser cutter can also be used for the said cutting | disconnection. From the viewpoint of peelability of each substrate, a rotary punching device is preferable. In this step, it is preferable that the blade B is passed through the temporary separator 6 and the adhesive layer 2 at a depth reaching the heavy release separator 3 to cut the temporary separator 6 and the adhesive layer 2. Thereby, the notch part 3c is formed in the surface 3b by the side of the adhesion layer 2 of the heavy peeling separator 3, and peeling of the heavy peeling separator 3 from the adhesion layer 2 becomes easy.

  Subsequently, the outer portions of the temporary separator 6 and the adhesive layer 2 are removed as shown in FIG. 6, the temporary separator 6 is peeled off from the adhesive layer 2 as shown in FIG. 7, and the adhesive as shown in FIG. A light release separator 4 is affixed to layer 2. The adhesive sheet 1 is completed through the above steps.

<Image display device>
Next, an image display device manufactured using the adhesive sheet 1 will be described. The pressure-sensitive adhesive layer 2 included in the pressure-sensitive adhesive sheet 1 can be applied to various image display devices. Examples of the image display device include a plasma display (PDP), a liquid crystal display (LCD), a cathode ray tube (CRT), a field emission display (FED), an organic EL display (OELD), a 3D display, and electronic paper (EP). . The adhesive layer 2 of the present embodiment is used for combining and bonding functional layers having functionality such as an antireflection layer, an antifouling layer, a dye layer, and a hard coat layer of an image display device, and a transparent protective plate. You can also.

  The antireflection layer may be any layer having antireflection properties such that the visible light reflectance is 5% or less, and a layer treated with a known antireflection method on a transparent substrate such as a transparent plastic film. Can be used.

  The antifouling layer is for preventing the surface from getting dirty, and a known layer composed of a fluorine-based resin or a silicone-based resin can be used to reduce the surface tension.

  The dye layer is used to increase color purity, and is used to reduce unnecessary light when the color purity of light emitted from an image display unit such as a liquid crystal display unit is low. The pigment | dye which absorbs the light of an unnecessary part can be obtained by making it melt | dissolve in resin and forming or laminating | stacking on base films, such as a polyethylene film and a polyester film.

  The hard coat layer is used to increase the surface hardness. As a hard-coat layer, what formed or laminated | stacked acrylic resin, such as urethane acrylate and an epoxy acrylate; base films, such as a polyethylene film, can be used, for example. Similarly, in order to increase the surface hardness, it is also possible to use a hard coat layer formed or laminated on a transparent protective plate such as glass, acrylic resin or polycarbonate.

  The adhesive layer 2 can be used by being laminated on a polarizing plate. In this case, it can also laminate | stack on the visual recognition surface side of a polarizing plate, and can also laminate | stack on the opposite side.

  When used on the viewing surface side of the polarizing plate, an antireflection layer, an antifouling layer, and a hard coat layer can be laminated on the viewing surface side of the adhesive layer 2 and used between the polarizing plate and the liquid crystal cell. In this case, a functional layer can be laminated on the viewing surface side of the polarizing plate.

  When setting it as such a laminated body, the adhesion layer 2 can be laminated | stacked using a roll lamination, a vacuum bonding machine, or a single wafer bonding machine.

  The adhesive layer 2 is preferably disposed at an appropriate position on the viewing side between the image display unit of the image display device and the transparent protective plate on the foremost viewing side. Specifically, it is preferably applied between the image display unit and the transparent protective plate.

  In the image display device in which the touch panel is combined with the image display unit, the adhesive layer 2 of the present embodiment is preferably used between the touch panel and the image display unit and / or between the touch panel and the transparent protective plate. However, as long as the adhesive layer 2 of the present embodiment is applicable to the configuration of the image display device, the position is not limited to the above-described position.

  Hereinafter, a liquid crystal display device which is one of image display devices will be described in detail with reference to FIGS. 9 and 10 as an example.

  FIG. 9 is a side sectional view schematically showing one embodiment of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 9 includes an image display unit 7 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 12, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. The transparent resin layer 32 provided on the upper surface 20 and a transparent protective plate (protective panel) 40 provided on the surface thereof. A step 60 provided on the surface of the transparent protective plate 40 is embedded with a transparent resin layer 32. The transparent resin layer 32 basically corresponds to the adhesive layer of this embodiment. Although the thickness of the step 60 varies depending on the size of the liquid crystal display device and the like, it is particularly useful to use the adhesive layer of this embodiment when the thickness is 40 to 100 μm.

  FIG. 10 is a side cross-sectional view schematically showing a liquid crystal display device equipped with a touch panel, which is an embodiment of the liquid crystal display device of the present invention. 10 includes an image display unit 7 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 12, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. 20, a transparent resin layer 32 provided on the top surface, a touch panel 30 provided on the top surface of the transparent resin layer 32, a transparent resin layer 31 provided on the top surface of the touch panel 30, and a transparent protective plate provided on the surface thereof 40. The step 60 provided on the surface of the transparent protective plate 40 is embedded with the transparent resin layer 31. The transparent resin layer 31 and the transparent resin layer 32 basically correspond to the adhesive layer of this embodiment.

In the liquid crystal display device of FIG. 10, the transparent resin layer is interposed both between the image display unit 7 and the touch panel 30 and between the touch panel 30 and the transparent protective plate 40 having the step 60. The transparent resin layer only needs to be interposed in at least one of these, and when using the adhesive layer 2 of the present embodiment, it is preferable to interpose between the touch panel 30 and the transparent protective plate 40 having the step 60. When the touch panel is on-cell, the touch panel and the liquid crystal display cell are integrated. As a specific example, the liquid crystal display cell 12 of the liquid crystal display device of FIG. 9 may be replaced with an on-cell.
In recent years, development of a liquid crystal display cell incorporating a touch panel function, called an in-cell type touch panel, is in progress. The liquid crystal display device provided with such a liquid crystal display cell is composed of a transparent protective plate, a polarizing plate, and a liquid crystal display cell (liquid crystal display cell with a touch panel function), and the adhesive layer 2 of the present embodiment of the present invention is The liquid crystal display device adopting such an in-cell type touch panel can be suitably used.

  According to the liquid crystal display device shown in FIG. 9 and FIG. 10, since the adhesive layer of this embodiment is provided as the transparent resin layer 31 or 32, it has impact resistance, has no double image, and has a clear and high contrast image. can get.

  The liquid crystal display cell 12 can be made of a liquid crystal material well known in the art. Further, depending on the control method of the liquid crystal material, it is classified into TN (Twisted Nematic) method, STN (Super-Twisted Nematic) method, VA (Vertical Alignment) method, IPS (In-Place-Switching) method, etc. Then, it may be a liquid crystal display cell using any control method.

  As the polarizing plates 20 and 22, a polarizing plate common in this technical field can be used. The surfaces of these polarizing plates may be subjected to treatments such as antireflection, antifouling, and hard coat. Such surface treatment may be performed on one side of the polarizing plate or on both sides thereof.

  As the touch panel 30, a resistive film method in which an electrode comes in contact with the pressure of a finger or object touching the surface, a capacitance method that senses a change in capacitance when the finger or object touches the surface, an electromagnetic induction method, or the like However, the adhesive layer 2 of the present invention is particularly suitable for use in a liquid crystal display device employing a capacitive touch panel. As the touch panel 30, a touch panel generally used in this technical field can be used. For example, the capacitive touch panel has a structure in which a transparent electrode is formed on a substrate. Can be mentioned. Examples of the substrate include a glass substrate, a polyethylene terephthalate film, and a cycloolefin polymer film. Moreover, as a transparent electrode, metal oxides, such as ITO (Indium Tin Oxide), are mentioned, for example. The thickness of the substrate is 20 to 1,000 μm. The transparent electrode has a thickness of 10 to 500 nm.

  The transparent resin layer 31 or 32 can be formed with a thickness of 0.02 to 3 mm, for example. In particular, in the pressure-sensitive adhesive layer 2 of the present embodiment, a thicker film can exhibit a more excellent effect, and it is preferably used when forming the transparent resin layer 31 or 32 of 100 μm or more and 500 μm or less. it can.

  As the transparent protective plate 40, a general optical transparent substrate can be used. Specific examples thereof include inorganic plates such as glass substrates and quartz plates; plastic substrates such as acrylic resin substrates, polycarbonate plates and cycloolefin polymer plates; resin sheets such as thick polyester sheets. When high surface hardness is required, a glass substrate and an acrylic resin substrate are preferable, and a glass substrate is more preferable. The surface of these transparent protective plates may be subjected to treatments such as antireflection, antifouling, and hard coat. Such surface treatment may be performed on one side of the transparent protective plate or on both sides. A plurality of transparent protective plates can be used in combination.

  The backlight system 50 typically includes a reflecting unit such as a reflecting plate and an illuminating unit such as a lamp.

<Method for Manufacturing Image Display Device>
The pressure-sensitive adhesive sheet 1 is used as follows in assembling an image display device or the like. First, as shown in FIG. 11, the light release separator 4 is peeled from the adhesive sheet 1 to expose the adhesive surface 2 b of the adhesive layer 2. Subsequently, as shown in FIG. 12, the adhesive surface 2 b of the adhesive layer 2 is attached to the adherend A <b> 1 and pressed with a roller R or the like. At this time, the step 60 provided on the surface of the adherend A <b> 1 is embedded by the adhesive layer 2. The adherend A1 is, for example, an image display unit, a transparent protective plate, or a touch panel. Subsequently, as shown in FIG. 13, the heavy release separator 3 is peeled from the adhesive layer 2 to expose the adhesive surface 2 c of the adhesive layer 2. Subsequently, as shown in FIG. 14, the adhesive surface 2 c of the adhesive layer 2 is attached to the adherend A <b> 2 and subjected to a heating and pressurizing process (autoclave process). The adherend A2 is, for example, an image display unit, a transparent protective plate, or a touch panel. In this way, the adherends can be bonded together via the adhesive layer 2. In this case, the heat and pressure treatment conditions are such that the temperature is 30 to 80 ° C. and the pressure is 0.3 to 0.8 MPa. If the step on the surface of the adherend is 10 to 40 μm, the vicinity of the step It is preferable that the temperature is 30 to 60 ° C. and the pressure is 0.3 to 0.5 MPa from the viewpoint of further removing the bubbles. Further, the treatment time is preferably 5 to 60 minutes, and more preferably 10 to 30 minutes.

  Moreover, the said manufacturing method may also include the process of irradiating an ultraviolet-ray with respect to the adhesion layer 2 from either one side of both adherends (for example, a transparent protective board, a touch panel) before or after an autoclave process. Thereby, the reliability (reduction of bubbles and suppression of peeling) and adhesive strength under high temperature and high humidity can be further improved. From the viewpoint of further improving the reliability under high temperature and high humidity, it is possible to irradiate ultraviolet rays from the side of an adherend (for example, a touch panel) that does not have a stepped portion.

Although there is no restriction | limiting in particular in the irradiation amount of an ultraviolet-ray, It is preferable that it is about 500-5,000mJ / cm < ² >. In addition, it is preferable to perform the process of irradiating an ultraviolet-ray after an autoclave process from a viewpoint of improving the reliability in high temperature, high humidity.

  In the structure thus obtained, when a glass substrate (soda lime glass) is employed as an adherend, the tensile shear adhesive force at 85 ° C. between the adhesive layer 2 and the glass substrate is 250 to 500 N / 25 mm. It is preferably × 25 mm □, more preferably 300 to 500 N / 25 mm × 25 mm □, and still more preferably 300 to 400 N / 25 mm × 25 mm □. In addition, said tensile shear adhesive force is 85 degreeC temperature environment using the tensile testing machine (Orientec Co., Ltd. make, brand name "TENSILON RTC-1210" ("TENSILON" is a registered trademark.)) It can be measured at a tensile speed of 30 mm / min.

  Through the above steps, the adhesive layer 2 is disposed between the adherend A1 and the adherend A2. In particular, the adhesive layer 2 is preferably used by being disposed between the transparent protective plate and the touch panel, or between the touch panel and the image display unit.

  The above-described liquid crystal display device of FIG. 9 can be manufactured by obtaining a laminate by interposing the adhesive layer 2 of the present embodiment between the image display unit 7 and the transparent protective plate 40. That is, in the image display device illustrated in FIG. 9, the adhesive layer 2 of the present embodiment can be laminated on the upper surface of the polarizing plate 20 by a laminating method.

  The above-described liquid crystal display device of FIG. 10 is manufactured by obtaining the laminate by interposing the adhesive layer 2 of the present embodiment between the image display unit and the touch panel and / or between the touch panel and the transparent protective plate. can do.

[Second Embodiment]
<Adhesive sheet for image display device>
The pressure-sensitive adhesive sheet 1 for an image display device according to this embodiment is further laminated on a film-like pressure-sensitive adhesive layer, first and second base material layers laminated so as to sandwich the pressure-sensitive adhesive layer, and a second base material layer. And the outer edges of the first base material layer and the carrier layer project outward from the outer edge of the adhesive layer.

  That is, as shown in FIG. 15 and FIG. 16, the pressure-sensitive adhesive sheet 1 according to this embodiment includes a transparent film-like pressure-sensitive adhesive layer 2 and a light release separator 4 (first film) that is laminated so as to sandwich the pressure-sensitive adhesive layer 2. ) And a heavy release separator 3 (second base material layer), and a carrier film 5 (carrier layer) further laminated on the heavy release separator 3.

  The outer edge 5a of the carrier film 5 may protrude outward from the outer edge 2a of the adhesive layer 2 from the viewpoint of protecting the outer edge portion of the adhesive layer, ease of handling, ease of peeling, and reducing adhesion of dust and the like. preferable. Further, since the outer edge 5a of the carrier film 5 projects outward from the outer edge 2a of the adhesive layer 2, the carrier film 5 is pinched by the second base material layer by pinching the outer edge of the carrier film 5 projecting outward. Can be easily peeled off. Moreover, it is preferable that the outer edge 5 a of the carrier film 5 projects outward from the outer edge 4 a of the light release separator 4. Thereby, since the outer edge part of the carrier film 5 becomes easier to pinch, the carrier film 5 can be peeled off more easily. The width at which the outer edge 5a of the carrier film 5 protrudes from the outer edge 4a of the light release separator 4 is 0.5 mm or more and 10 mm or less from the viewpoint of ease of handling, ease of peeling, and adhesion of dust and the like. Preferably, it is 1 mm or more and 5 mm or less. When the planar shape of the carrier film 5, the adhesive layer 2, the heavy release separator 3 and the light release separator 4 is a substantially rectangular shape such as a substantially rectangular shape, the outer edge 5 a of the carrier film 5 is more than the outer edge 4 a of the light release separator 4. The overhanging width is preferably 0.5 mm or more and 10 mm or less on at least one side, more preferably 1 mm or more and 5 mm or less on at least one side, and 0.5 mm or more and 10 mm or less on all sides. More preferably, it is particularly preferably 1 mm or more and 5 mm or less on all sides.

  Since the heavy release separator 3 is protected by the carrier film 5 until immediately before the process, the surface of the heavy release separator 3 is less damaged. Thereby, the damage | wound of the adhesion layer 2 can be visually recognized easily, and can be easily excluded before sticking the adhesion layer 2 which the damage | wound has produced on the to-be-adhered thing.

  The carrier film 5 is, for example, a polymer film such as polyethylene terephthalate, polypropylene, polyethylene, or polyester, and among them, a polyethylene terephthalate film is preferable. From the viewpoint of workability, the thickness of the carrier film 5 is preferably 15 μm or more and 100 μm or less, more preferably 20 μm or more and 80 μm or less, and further preferably 20 μm or more and 50 μm or less.

  The peel strength between the light release separator 4 and the adhesive layer 2 is lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. The peel strength between the carrier film 5 and the heavy release separator 3 is lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. Here, the peel strength between the carrier film 5 and the heavy release separator 3 is more preferably lower than the peel strength between the light release separator 4 and the pressure-sensitive adhesive layer 2, but even if high, the effect of the present application is impaired. There is no.

  The peel strength between the carrier film 5 and the heavy release separator 3 is adjusted by, for example, the type of the adhesive layer formed between the carrier film 5 and the heavy release separator 3 and the thickness of the adhesive layer. As a kind of adhesive agent used for the adhesive bond layer formed between the carrier film 5 and the heavy peeling separator 3, an acrylic adhesive is mentioned, for example. 0.1-10 micrometers is preferable and, as for the thickness of the adhesive bond layer formed between the carrier film 5 and the heavy peeling separator 3, 1-5 micrometers is more preferable.

  As described above, according to the pressure-sensitive adhesive sheet 1 of the present embodiment, the separators 3 and 4 and the carrier film 5 can be reliably peeled in a predetermined order without any defective peeling while protecting the pressure-sensitive adhesive layer 2.

<Method for producing pressure-sensitive adhesive sheet for image display device>
The pressure-sensitive adhesive sheet 1 of the present embodiment is manufactured as follows. First, as shown in FIG. 17, a base material film 10 in which a heavy release separator 3, an adhesive layer 2, and a temporary separator 6 are sequentially laminated on a carrier film 5 is prepared. The heavy release separator 3 is bonded to the carrier film 5 through the adhesive layer. The temporary separator 6 is, for example, a layer made of the same material as the light release separator 4.

  Subsequently, the temporary separator 6, the adhesive layer 2, and the heavy release separator 3 are cut into a desired shape by a punching device (not shown) provided with the blade B. In this step, as shown in FIG. 18, it is preferable to pass the blade B through the temporary separator 6, the adhesive layer 2, and the heavy release separator 3 at a depth reaching the carrier film 5. Thereby, the notch part 5c is formed in the surface 5b by the side of the adhesion layer 2 of the carrier film 5. FIG. Thus, the adhesive layer 2 and the heavy release separator 3 can be completely cut by allowing the blade B to reach the carrier film 5 from the temporary separator 6.

  Subsequently, as shown in FIG. 19, the outer portions of the temporary separator 6, the adhesive layer 2 and the heavy release separator 3 are removed. At this time, the outer edge of the heavy release separator 3 is substantially flush with the outer edge of the carrier film 5 as shown in FIG. 20 so that the outer edge of the carrier film 5 does not protrude outward from the outer edge of the heavy release separator 3. It is preferable. That is, only the outer part of the temporary separator 6 and the adhesive layer 2 is removed, and the outer part of the heavy release separator 3 is left on the carrier film 5 without being removed. The heavy release separator 3 after cutting is attached to the carrier film 5 as it is. It is preferable that the Thereby, the problem that the surface-exposed carrier film 5 adheres to other portions can be effectively prevented.

  After removing the outer portions of the temporary separator 6, the adhesive layer 2 and the heavy release separator 3 as shown in FIG. 19, the temporary separator 6 is subsequently released from the adhesive layer 2 as shown in FIG. A light release separator 4 is affixed to the adhesive layer 2 as shown. The pressure-sensitive adhesive sheet 1 of this embodiment is completed through the above steps. Thus, if it is a film cut so that the outer edge of the heavy release separator 3 is substantially flush with the outer edge of the adhesive layer 2, the difference in ease of peeling between the light release separator 4 and the heavy release separator 3. Therefore, the light release separator 4 can be more easily peeled before the heavy release separator 3 is peeled off. Furthermore, since the position of the outer edge of the adhesive layer 2 becomes clear because the outer edge of the heavy release separator 3 and the outer edge of the adhesive layer 2 are aligned, the alignment between the adhesive layer 2 and the adherend becomes easy.

<Method for Manufacturing Image Display Device>
The pressure-sensitive adhesive sheet 1 of the present embodiment is the same as the pressure-sensitive adhesive sheet of the first embodiment except that the carrier film 5 is first peeled off from the heavy release separator 3 as shown in FIG. Can be used.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not necessarily limited to the said embodiment, A various change is possible in the range which does not deviate from the summary.

  Hereinafter, the present invention will be described in more detail with reference to examples. In this example, the pressure-sensitive adhesive sheets according to the first embodiment and the second embodiment are produced, but the present invention is not limited to these examples.

Synthesis Example 1 (Synthesis of acrylic acid derivative polymer (A-1))
A reaction vessel equipped with a cooling tube, a thermometer, a stirring device, a dropping funnel and a nitrogen introduction tube was used as an initial monomer, and 84.0 g of 2-ethylhexyl acrylate, 36.0 g of 2-hydroxyethyl acrylate, 100.0 g of methyl ethyl ketone and 100 of ethyl acetate were used. 0.0 g was weighed and heated from room temperature (25 ° C.) to 82 ° C. in 30 minutes while replacing the nitrogen with an air flow of 100 ml / min. Thereafter, 196.0 g of 2-ethylhexyl acrylate and 84.0 g of 2-hydroxyethyl acrylate were used as additional monomers while maintaining the temperature at 82 ° C., and these were added to t-butylperoxy-2-ethylhexanoate 2 A solution in which 0.0 g was dissolved was prepared, and this solution was added dropwise over 120 minutes. After completion of dropping, the reaction was further continued for 2 hours.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer resin (weight average molecular weight 250,000) of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate.

Synthesis Example 2 (Synthesis of acrylic acid derivative polymer (A-2))
A reaction vessel equipped with a condenser, a thermometer, a stirring device, a dropping funnel and a nitrogen introducing tube was used as an initial monomer, 84.0 g of 2-ethylhexyl acrylate, 36.0 g of 2-hydroxyethyl acrylate, 60.0 g of methyl ethyl ketone and 140 of ethyl acetate. 0.0 g was weighed and heated from room temperature (25 ° C.) to 80 ° C. for 30 minutes while replacing nitrogen with an air flow of 100 ml / min. Thereafter, 196.0 g of 2-ethylhexyl acrylate and 84.0 g of 2-hydroxyethyl acrylate were used as additional monomers while maintaining the temperature at 80 ° C., and these were added to t-butylperoxy-2-ethylhexanoate 2 A solution in which 0.0 g was dissolved was prepared, and this solution was added dropwise over 120 minutes. After completion of dropping, the reaction was further continued for 2 hours.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer resin of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 320,000).

Synthesis Example 3 (Synthesis of acrylic acid derivative polymer (A-3))
A reaction vessel equipped with a cooling tube, a thermometer, a stirring device, a dropping funnel, and a nitrogen introduction tube was used as initial monomers as 84.0 g 2-ethylhexyl acrylate, 36.0 g 2-hydroxyethyl acrylate, 50.0 g methyl ethyl ketone, and 150 ethyl acetate. 0.0 g was weighed and heated from room temperature (25 ° C.) to 78 ° C. in 30 minutes while replacing the nitrogen with an air flow of 100 ml / min. Thereafter, 196.0 g of 2-ethylhexyl acrylate and 84.0 g of 2-hydroxyethyl acrylate were used as additional monomers while maintaining the temperature at 78 ° C., and these were added to t-butylperoxy-2-ethylhexanoate 2 A solution in which 0.0 g was dissolved was prepared, and this solution was added dropwise over 120 minutes. After completion of dropping, the reaction was further continued for 2 hours.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer resin (weight average molecular weight 400,000) of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate.

Synthesis Example 4 (Synthesis of acrylic acid derivative polymer (A-4))
200.0 g of methyl ethyl ketone was weighed in a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and a nitrogen introducing tube, and the temperature was changed from room temperature (25 ° C.) to 80 for 30 minutes while replacing nitrogen with an air flow of 100 ml / min. Heated to ° C. Thereafter, while maintaining the temperature at 80 ° C., 280.0 g of 2-ethylhexyl acrylate and 120.0 g of 2-hydroxyethyl acrylate were used as monomers, and t-butylperoxy-2-ethylhexanoate 6 was added thereto. A solution in which 0.0 g was dissolved was prepared, and this solution was added dropwise over 120 minutes. After completion of dropping, the reaction was further continued for 2 hours.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer resin of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 20,000).

Synthesis Example 5 (Synthesis of acrylic acid derivative polymer (A-5))
Weighed 84.0 g of 2-ethylhexyl acrylate, 36.0 g of 2-hydroxyethyl acrylate, and 200.0 g of methyl ethyl ketone as initial monomers in a reaction vessel equipped with a condenser, thermometer, stirrer, dropping funnel and nitrogen inlet tube. While substituting with nitrogen with an air volume of 100 ml / min, heating was performed from room temperature (25 ° C.) to 80 ° C. in 30 minutes. Thereafter, while maintaining the temperature at 80 ° C., 196.0 g of 2-ethylhexyl acrylate and 84.0 g of 2-hydroxyethyl acrylate were used as additional monomers, and t-butylperoxy-2-ethylhexanoate 5 A solution in which 0.0 g was dissolved was prepared, and this solution was added dropwise over 120 minutes. After completion of dropping, the reaction was further continued for 2 hours.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer resin of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 150,000).

Synthesis Example 6 (Synthesis of polyurethane diacrylate (C-1))
285.3 g of polypropylene glycol (number average molecular weight 2,000), unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (manufactured by Daicel Corporation) in a reaction vessel equipped with a cooling tube, thermometer, stirring device, dropping funnel and air inlet tube , 24.5 g of the trade name “Placcel FA2D” (“Placcel” is a registered trademark)), 0.13 g of p-methoxyphenol as a polymerization inhibitor and 0.5 g of dibutyltin dilaurate as a catalyst, and an air volume of 100 ml / min. The mixture was heated from room temperature (25 ° C.) to 75 ° C. in 15 minutes while flowing air. Thereafter, while maintaining the temperature at 75 ° C., 39.6 g of isophorone diisocyanate was uniformly added dropwise over 2 hours to carry out the reaction.
After completion of the dropwise addition, the reaction was allowed to proceed for 6 hours. As a result of IR measurement, it was confirmed that the isocyanate group had disappeared, and the reaction was terminated. Polyurethane acrylate having polypropylene glycol and isophorone diisocyanate as repeating units and having (meth) acryloyl groups at both ends (weight average molecular weight 30, 000).

  The weight average molecular weight is measured using gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and converted using a standard polystyrene calibration curve using the following equipment and measurement conditions. It is the value decided by doing. In preparing the calibration curve, 5 sample sets (PStQuick MP-H, PStQuick B (trade name (“PStQuick” is a registered trademark))) manufactured by Tosoh Corporation were used as standard polystyrene.

Device: High-speed GPC device HLC-8320GPC (detector: differential refractometer)
(Product name “HLC-8320GPC” manufactured by Tosoh Corporation is a registered trademark.))
Solvent: Tetrahydrofuran (THF)
Column: Column TSKgel SuperMultipore HZ-H
(Product name (“TSKgel SuperMultipore” is a registered trademark) manufactured by Tosoh Corporation)
Column size: Column length is 15 cm, column inner diameter is 4.6 mm
Measurement temperature: 40 ° C
Flow rate: 0.35 ml / min
Sample concentration: 10 mg / THF 5 ml
Injection volume: 20 μl

The following each component used as the raw material of an adhesive resin composition was prepared.
Component A: Acrylic acid derivative polymer (A-1) to (A-5)
Component B: Isostearyl acrylate (ISTA)
: 2-ethylhexyl acrylate (2EHA)
: 4-hydroxybutyl acrylate (4HBA)
: Acryloylmorpholine (ACMO)
Component C: Polyurethane diacrylate (C-1)
D component: 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, trade name “Irgacure-184” (“Irgacure” is a registered trademark), hereinafter I-184)

<Example 1>
[Preparation of adhesive sheet 1 (three-layer product)]
Using 75 μm thick polyethylene terephthalate (made by Fujimori Kogyo Co., Ltd.) as the heavy release separator 3 and 50 μm thick polyethylene terephthalate (made by Fujimori Kogyo Co., Ltd.) as the light release separator 4 and the temporary separator 6, the following (I ) To (V), the pressure-sensitive adhesive sheet 1 was produced.
(I) 35.0 g of acrylic acid derivative polymer (A-1), 31.5 g of 2-ethylhexyl acrylate (2EHA), 5.0 g of isostearyl acrylate (ISTA), 5.0 g of 4-hydroxybutyl acrylate (4HBA), 17.0 g of acryloylmorpholine (ACMO), 6.0 g of polyurethane diacrylate (C-1), 0.5 g of 1-hydroxycyclohexyl phenyl ketone (I-184) are weighed and mixed by stirring at room temperature. A liquid adhesive resin composition was obtained.

(II) After coating this adhesive resin composition on the heavy release separator 3 to form a coating film, a temporary separator 6 is laminated on the adhesive layer 2, and an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd.). Was used to obtain a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer 2 sandwiched between the heavy release separator 3 and the temporary separator 6 by irradiation with ultraviolet rays (2,000 mJ / cm ² ). The adhesive layer 2 was coated by adjusting the thickness to 150 μm.

(III) The laminate was cut with a rotary blade having a diameter of 72 mm so as to have a size of 220 mm × 180 mm.

(IV) The adhesive layer 2 and the temporary separator 6 in the cut laminate were cut with a rotary blade having a diameter of 72 mm so as to have a size of 205 mm × 160 mm. At this time, both sides on the long side of the heavy release separator 3 protrude 7.5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the heavy release separator 3 are adhesive layer 2. It cut | disconnected so that it might protrude from both sides of the short side of 10 mm. For the cutting of (III) and (IV), a rotary punching device equipped with a rotary blade having a diameter of 72 mm was used.

(V) The temporary separator 6 was peeled off, and a light release separator 4 having a size of 215 mm × 170 mm was laminated on the adhesive layer 2. Thus, the adhesive sheet 1 was obtained. At this time, both sides on the long side of the light release separator 4 protrude 5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the light release separator 4 are short sides of the adhesive layer 2. Lamination was carried out so as to protrude 5 mm from both sides.

<Examples 2 and 3 and Comparative Examples 1 and 2>
A pressure-sensitive adhesive sheet 1 was obtained in the same manner as in Example 1 except that the blending conditions were as shown in Table 1. In Table 1, the unit of the numerical value representing the blending amount is part by mass.

[Various evaluations]
About the adhesive sheet obtained by each Example and the comparative example, the following (1)-(6) evaluation was performed.

(1) Optical characteristics The pressure-sensitive adhesive sheet obtained in the above procedure (II) was left in an environment of 85 ° C. and 85% RH for 24 hours. Next, the pressure-sensitive adhesive sheet was cut into a size of 40 mm in width and 100 mm in length, and the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet was peeled off on soda lime glass having a size of 50 mm × 100 mm × 3 mm (thickness), and a hand roller (25 ° C., load: 500 gf (4.9 N)). Next, the polyethylene terephthalate film on the opposite surface of the pressure-sensitive adhesive sheet was peeled off, and the pressure-sensitive adhesive layer surface was measured as the light source side.
(1-1) Measurement of turbidity (haze) Measured according to JIS K 7361 using a turbidimeter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: NHD-2000).
Haze (%) = (Td / Tt) × 100
Td: diffuse transmittance Tt: total light transmittance

(2) Measurement of tan δ Three adhesive layers having a thickness of 150 μm obtained in the above procedure (II) were stacked to a thickness of about 450 μm, and cut into dimensions of 10 mm width and 10 mm length to prepare a sample. . Two samples were prepared, and as shown in FIG. 24, the sample S was sandwiched between the plate P1 at both ends and the center plate P2 using a jig 100 to obtain a measurement sample. Then, tan δ of the sample was measured using a wide-range dynamic viscoelasticity measuring apparatus (trade name “Solid Analyzer RSA-III” manufactured by Rheometric Scientific). The measurement conditions were “shear sandwich mode, frequency 1.0 Hz, measurement temperature range −20 to 100 ° C., temperature increase rate 5 ° C./min”.

(3) Tensile shear adhesive force After the pressure-sensitive adhesive sheet obtained in the above procedure (II) was cut into a size of 25 mm in width and 25 mm in length, the polyethylene terephthalate film on one side was peeled off, and 30 mm × 100 mm × 3 mm (thickness) A) A soda lime glass having a size was laminated using a hand roller (25 ° C., load: 500 gf (4.9 N)). Subsequently, the polyethylene terephthalate film on the opposite surface of the pressure-sensitive adhesive sheet was peeled off, and soda lime glass having the same shape as above was bonded using a hand roller (25 ° C., load: 500 gf (4.9 N)). Next, autoclaving (30 ° C., 0.3 MPa) was performed for 1 minute to obtain a sample. Thereafter, the tensile shear adhesive force was measured at a tensile speed of 30 mm / min under a temperature environment of 85 ° C. using a tensile tester (manufactured by Orientec Co., Ltd., trade name: TENSILON RTC-1210).

(4) Step following ability The pressure-sensitive adhesive sheet obtained in the above procedure (II) is cut into dimensions of 50 mm in width and 80 mm in length, the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet is peeled off, and 56 mm × 86 mm × 0. The soda lime glass having a size of 5 mm (thickness) was bonded using a hand roller (25 ° C., load: 500 gf (4.9 N)). Next, after peeling off the polyethylene terephthalate film on the other side of the pressure-sensitive adhesive sheet on which the soda lime glass was not bonded, the outer peripheral part was provided with a printing layer (step 60) having a width of 9 mm and a thickness of 30 μm. 56 mm × 86 mm A glass substrate having a size of 0.7 mm (thickness) is vacuum sealed at 60 ° C., 0.5 MPa using a vacuum bonding apparatus (manufactured by Takatori Co., Ltd., trade name “TPL-0512MH”) so as to sandwich the adhesive layer. Bonding was performed for 60 seconds under the condition of a degree of 50 Pa. Thereafter, autoclaving (45 ° C., 0.5 MPa) was performed for 10 minutes to obtain an evaluation sample.
Using this evaluation sample, appearance evaluation (bubbles, peeling) of the periphery of the printed layer (step 60) was performed with an optical microscope, and the step following ability was determined according to the following evaluation criteria.
(Evaluation criteria)
A: No bubbles and no peeling B: Bubbles or peeling on only one side C: Bubbles or peeling on two or more sides

(5) Bubble resistance The evaluation sample was produced like (4).
(5-1) Bubble resistance (high temperature)
After visually confirming the bubbles of the prepared evaluation sample, the evaluation sample was put into a thermostat at 80 ° C. and left for 24 hours. After leaving, the bubbles newly generated in the evaluation sample were visually confirmed.
(Evaluation criteria)
A: No bubbles are generated.
B: 1-5 occurrences.
C: 5 or more occurred.
(5-2) Bubble resistance (high temperature and high humidity)
After visually confirming the bubbles of the prepared evaluation sample, the evaluation sample was put into a constant temperature and humidity chamber at 85 ° C. and 85% RH and left for 24 hours. After leaving, the bubbles newly generated in the evaluation sample were visually confirmed.
(Evaluation criteria)
A: No bubbles are generated.
B: 1-5 occurrences.
C: 5 or more occurred.
(5-3) Bubble resistance (combined test)
After visually confirming the bubbles in the prepared evaluation sample, the evaluation sample was immersed in a water bath at 80 ° C. and left for 1 hour. Next, the sample was taken out from the hot water, wiped off the water droplets adhering to the surface, and then taken out from the hot water, 5 minutes later, the sample was put into a constant temperature bath at 80 ° C. and left for 24 hours. After leaving, the bubbles newly generated in the evaluation sample were visually confirmed.
(Evaluation criteria)
A: No bubbles are generated.
B: 1-5 occurrences.
C: 5 or more occurred.

  The evaluation results of each example and comparative example are shown in Table 1.

  As is apparent from Table 1, it was confirmed that the pressure-sensitive adhesive sheets of the examples were excellent in step following ability, transparency after being left in a high-temperature and high-humidity environment, and bubble resistance.

<Example 4>
[Preparation of adhesive sheet 1 (4-layer product)]
(I) A liquid adhesive resin composition was obtained in the same manner as in Example 1.
(II) After coating this adhesive resin composition on one surface of the heavy release separator 3 to form a coating film, the temporary separator 6 is laminated on the adhesive layer 2 and irradiated with ultraviolet rays (2000 mJ / cm ² ) After that, an acrylic adhesive (Hitalex K-6040 (trade name), manufactured by Hitachi Chemical Co., Ltd. (“Hitalex” is a registered trademark)) is laminated on the other surface of the heavy release separator 3. The carrier film 5 was laminated thereon.
(III) The heavy release separator 3, the adhesive layer 2, the temporary separator 6 and the carrier film 5 were cut so as to be 220 mm × 180 mm.
(IV) The adhesive layer 2, the heavy release separator 3, and the temporary separator 6 were cut to a size of 205 mm × 160 mm. For the cutting, a rotary punching device equipped with a rotary blade having a diameter of 72 mm was used. At this time, both long sides of the carrier film 5 protrude 7.5 mm from both long sides of the adhesive layer 2, and both short sides of the carrier film 5 are short of the adhesive layer 2. It cut | disconnected so that it might protrude 10 mm from both sides of a side.
(V) The temporary separator 6 was peeled off, and a light release separator 4 having a size of 215 mm × 170 mm was laminated on the adhesive layer 2. Thus, the adhesive sheet 1 was obtained. At this time, both sides on the long side of the light release separator 4 protrude 5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the light release separator 4 are short sides of the adhesive layer 2. Lamination was carried out so as to protrude 5 mm from both sides.

  When the pressure-sensitive adhesive sheet 2 was evaluated in the same manner as the pressure-sensitive adhesive sheet 1, a pressure-sensitive adhesive sheet having a desired shape could be produced. The result was excellent in both transparency and bubble resistance.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet for image display apparatuses provided with the adhesive layer excellent in level | step difference followability, transparency after leaving to stand in a high-temperature, high-humidity environment, and bubble resistance can be provided. A device in which such an adhesive layer is incorporated exhibits high reliability and can prevent a reduction in visibility. Therefore, the adhesive sheet of the present invention is suitable for use in an image display apparatus. In particular, it is extremely useful as a sheet material used when filling a space between an information input device such as a touch panel and a transparent protective plate.

  DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet, 2 ... Adhesive layer, 3 ... Heavy release separator, 4 ... Light release separator, 5 ... Carrier film, 6 ... Temporary separator, 2a, 3a, 4a, 5a ... Outer edge, 3b, 5b ... Adhesive layer side Surface, 3c, 5c ... notch, 10 ... base material film, B ... blade, 40 ... transparent protective plate (glass or plastic substrate), 7 ... image display unit, 12 ... liquid crystal display cell, 20, 22 ... polarizing plate , 30 ... touch panel, 31, 32 ... transparent resin layer, 50 ... backlight system, 60 ... step, 100 ... jig.

Claims (9)

  An adhesive layer and a pair of base material layers laminated so as to sandwich the adhesive layer, and the adhesive layer is derived from an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms. (Meth) acrylic acid derivative polymer (A) having a weight average molecular weight of 250,000 to 500,000 including structural units, (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule, The adhesive sheet for image display apparatuses formed from the adhesive resin composition containing the crosslinking agent (C) which has a bifunctional or more (meth) acryloyl group, and a photoinitiator (D). An adhesive layer, first and second base material layers laminated so as to sandwich the adhesive layer, and a carrier layer further laminated on the second base material layer,
The outer edges of the first base material layer and the carrier layer protrude outward from the outer edge of the adhesive layer, and the adhesive layer is made of an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms. (Meth) acrylic acid derivative polymer (A) having a weight average molecular weight of 250,000 to 500,000 including the derived structural unit, (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule ) A pressure-sensitive adhesive sheet for an image display device, which is formed from a pressure-sensitive adhesive resin composition containing a crosslinking agent (C) having a bi- or higher functional (meth) acryloyl group and a photopolymerization initiator (D).   The pressure-sensitive adhesive for an image display device according to claim 1, comprising stearyl (meth) acrylate as the (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the pressure-sensitive adhesive layer in the molecule. Sheet.   The pressure-sensitive adhesive sheet for an image display device according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a thickness of 50 to 500 µm.   The process of bonding adherends together and obtaining the laminated body through the adhesive layer provided in the adhesive sheet for an image display device according to any one of claims 1 to 4, and the laminated body, 30 to 80 The manufacturing method of an image display apparatus provided with the process of heat-pressing process on conditions (degreeC and 0.3-0.8 MPa).   The method for manufacturing an image display device according to claim 5, wherein the adherend is at least two selected from a transparent protective plate, a touch panel, and a liquid crystal display cell.   Weight including an image display unit, a transparent protective plate, and a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms interposed between the image display unit and the transparent protective plate (Meth) acrylic acid derivative polymer (A) having an average molecular weight of 250,000 to 500,000, (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule, bifunctional or higher ( The image display apparatus which has a laminated body containing the crosslinking agent (C) which has a (meth) acryloyl group, the adhesion layer containing a photoinitiator (D), or the transparent resin layer which is the hardened | cured material.   Weight including a structural unit derived from an alkyl (meth) acrylate having 4 to 18 carbon atoms in an alkyl group interposed between the image display unit, the touch panel, the transparent protective plate, and the touch panel and the transparent protective plate (Meth) acrylic acid derivative polymer (A) having an average molecular weight of 250,000 to 500,000, (meth) acrylic acid derivative monomer (B) having one (meth) acryloyl group in the molecule, bifunctional or higher ( The image display apparatus which has a laminated body containing the crosslinking agent (C) which has a (meth) acryloyl group, the adhesion layer containing a photoinitiator (D), or the transparent resin layer which is the hardened | cured material.   The image display device according to claim 7 or 8, wherein the image display unit, the touch panel, or the transparent protective plate has a stepped portion.

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