TW202223459A - Optical film with pressure-sensitive adhesive on both sides, and image display device - Google Patents

Abstract

An optical film (50) with a pressure-sensitive adhesive, the optical film (50) comprising: an optical film (11) having a first main surface and a second main surface; a first pressure-sensitive adhesive layer (21) disposed on the first main surface; and a second pressure-sensitive adhesive layer (22) disposed on the second main surface. The first main surface of the optical film includes a non-adhesion region (2x), where the optical film is exposed without being covered with the first pressure-sensitive adhesive layer, and an adhesion region, where the first pressure-sensitive adhesive layer has been disposed on the optical film. The non-adhesion region lies, for example, along the periphery of the optical film.

Description

Optical film with double-sided adhesive

The present invention relates to an optical film with an adhesive having an adhesive layer on both sides of the optical film, and an image display device.

Liquid crystal display devices and organic EL (Electroluminescence) display devices are widely used as various image display devices such as mobile phones, smart phones, car navigation devices, monitors, and televisions. Due to the display principle of the liquid crystal display device, a polarizing plate is arranged on the visible side surface of the liquid crystal cell. In a self-luminous display device such as organic EL, it is not necessary to install a polarizer in terms of the principle of image display, but in order to suppress the reflection of external light from the metal electrode (cathode), it may be seen as a mirror surface. The case where a circular polarizer (a laminate of a polarizer and a 1/4 wavelength plate) is arranged on the visible side surface.

Image display apparatuses in which a front surface transparent member such as a touch sensor and a cover glass are provided on the surface of an image display panel are becoming widespread, and this configuration is becoming mainstream in mobile applications and vehicle-mounted applications. By bonding the polarizing plate and the front transparent member through the adhesive layer, the difference in refractive index at the interface is reduced, and the reduction in visibility due to reflection or scattering can be suppressed. In order to form such an image display device, it is proposed to use a polarizing plate having an adhesive layer for bonding with the image display unit on one side and an adhesive layer for bonding with the front transparent plate on the other side. Double-sided adhesive film (for example, refer to Patent Document 1). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2014-115468

[Problems to be Solved by Invention]

As the demand for narrowing the edge of the display device increases, various studies have been carried out on the wiring of the outer periphery of the screen, the arrangement of the flexible printed wiring board, and the like. On the other hand, there is a tendency that the space for accommodating components of the image display device, such as a cover glass having a curved portion or a casing, is gradually limited at the end of the screen.

The present invention provides an image display device capable of securing a housing space for constituent members, and an optical film for an adhesive used in the image display device. [Technical means to solve problems]

The optical film with an adhesive of the present invention is provided with an adhesive layer on both sides of an optical film such as a polarizing plate. On at least one side of the optical film, there is a non-bonding area where the adhesive layer is not provided locally and the optical film is exposed. When the optical film of the double-sided adhesive is bonded to the image display panel and the front transparent member, the non-bonded area becomes a void. A component of an image display device of an image display device by arranging an electrical connection member such as a flexible printed wiring board (FPC), a curved surface portion of a casing or a front transparent plate, a resin material, a conductive material, etc., in the gap , can effectively use the space.

The optical film of the double-sided adhesive of the present invention includes an optical film such as a polarizing plate, a first adhesive layer provided on the first main surface of the optical film, and a second adhesive layer provided on the second main surface of the optical film agent layer. On the first main surface of the optical film, there is a non-bonding region where the first adhesive layer is not provided. In the image display device, the optical film and the transparent member on the front surface or the image display unit are bonded through the first adhesive layer, and a void is formed in the non-adhesive area where the first adhesive layer is not provided. By arranging the printed wiring board, the front surface transparent member, the case, the conductive paste, the resin material, etc. in the space, the space can be effectively utilized, and narrowing and miniaturization can be achieved.

[1st Embodiment] <Optical film with adhesive> The optical film of the double-sided adhesive of the first embodiment has a region (non-adhesive region) where the first adhesive layer is not provided and the optical film is exposed along the periphery of the first main surface of the optical film, and the optical film The area (the next area) on which the first adhesive layer is attached.

1A is a plan view of the first principal surface side of an optical film 51 with a double-sided adhesive according to an embodiment, and FIG. 1B is a cross-sectional view taken along the line B1-B2. The optical film 51 with double-sided adhesive is provided with the first adhesive layer 21 on one main surface of the optical film 11 , and has the second adhesive layer 22 on the other main surface.

(optical film) As the optical film 11, for example, a polarizing plate is used. In a general polarizing plate, an appropriate transparent protective film is arranged on one side or both sides of the polarizing element as needed. As the polarizer, for example, a hydrophilic film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film, which adsorbs a dichroic substance such as iodine or a dichroic dye, is used. The polymer film is formed by aligning dichroic substances by stretching. As the transparent protective film provided on the surface of the polarizing element, it is preferable to use a transparent film such as a cellulose-based resin, a cyclic polyolefin-based resin, an acrylic resin, a phenylmaleimide-based resin, or a polycarbonate-based resin. , Materials with excellent mechanical strength and thermal stability. As a transparent protective film of a polarizing element, optical anisotropic films, such as a retardation plate, can also be used.

The optical film 11 may be formed by laminating a plurality of films through an appropriate adhesive layer or adhesive layer. Examples of optical films other than polarizing plates include retardation films, viewing angle expansion films, viewing angle limiting (peep-proof) films, and brightness improving films for forming image display devices. A touch sensor and the like may also be provided in the optical film. In addition, a hard coat layer, an anti-reflection layer, an anti-glare layer, an anti-adhesion layer, etc. may be provided on the surface of the optical film, and a surface treatment for the purpose of improving adhesiveness and the like may also be performed.

(adhesive layer) The first adhesive layer 21 disposed on the first main surface of the optical film 11 and the second adhesive layer 22 disposed on the second main surface of the optical film 11 preferably contain an optically transparent adhesive. One of the first adhesive layer 21 and the second adhesive layer 22 is used for bonding the optical film 11 to the image display unit, and the other is used for the optical film 11 and the front surface transparent member (a transparent plate such as cover glass). , touch sensor, etc.)

As the adhesives constituting the adhesive layers 21 and 22, acrylic polymers, polysiloxane polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, and vinyl acetates can be appropriately selected. /Vinyl chloride copolymer, modified polyolefin, epoxy-based, fluorine-based, natural rubber, synthetic rubber and other rubber-based polymers are used. In particular, it is preferable to use an acrylic adhesive when it is excellent in optical transparency, exhibits moderate adhesion properties such as wettability, cohesion, and adhesiveness, and is also excellent in weather resistance, heat resistance, and the like. The first adhesive layer 21 and the second adhesive layer 22 may also be formed by laminating a plurality of adhesive layers.

The adhesive constituting the first adhesive layer 21 and the second adhesive layer 22 may also be a photo-curable adhesive that can be cured by light irradiation after being attached to an adherend such as an image display unit or a front transparent member. For example, if a photo-curable adhesive is used for lamination to a transparent member with a raised portion such as decorative printing, the adhesive before photo-curing is attached in a soft state and has level difference absorption. Thereby, mixing of air bubbles into the vicinity of the protruding portion and the like can be suppressed. Adhesion reliability can be improved by irradiating UV (Ultraviolet, ultraviolet) etc. after bonding to photoharden the adhesive. The photocurable adhesive is preferably, for example, one containing a polymer, a monomer or oligomer having a photopolymerizable functional group, and a photopolymerization initiator. A crosslinkable monomer having two or more polymerizable functional groups in one molecule can also be used as the monomer or oligomer having a photopolymerizable functional group.

The thickness of the adhesive layers 21 and 22 is not particularly limited, but is generally about 5 to 500 μm. The thickness of the adhesive used for laminating the optical film 11 and the image display unit is preferably about 5-50 μm. The thickness of the adhesive used for bonding the optical film 11 and the front transparent member may be appropriately set according to the configuration of the front transparent member. For example, when the front transparent member has a raised portion due to decorative printing, etc., in order to prevent air bubbles from entering the periphery of the raised portion, the thickness of the adhesive layer is preferably 50 μm or more so that it has Step Absorption.

(Non-adhesive area) In the optical film 51 with double-sided adhesive shown in FIG. 1 , a first adhesive is provided along the periphery of three sides 11a ₂ , 11a ₃ and 11a ₄ of the four sides of the optical film 11 Adjacent region of the agent layer 21 . The first adhesive layer 21 is not provided on the optical film 11 along the periphery of the side 11a ₁ extending in the y direction. In the non-bonding region 2x, the main surface of the optical film 11 is exposed, and there is a void on the optical film 11.

Along the peripheries of the sides 11a ₂ , 11a ₃ and 11a ₄ , the end face of the optical film 11 is aligned with the position of the end face of the first adhesive layer 21 . In the non-bonding area 2x along the side 11a ₁ , the end surface 21e of the first adhesive layer 21 is located more inward than the end surface 11e of the optical film 11 . The end faces 11e, 21e extend parallel to the y _- direction along the side 11a1.

The width W ₁ of the non-bonded region 2x, that is, the offset of the end face 21e of the first adhesive layer 21 from the end face 11e of the optical film 11 may be set according to the shape or size of the member provided in the non-bonded region. W ₁ is preferably 10 μm or more, more preferably 50 μm or more, and still more preferably 100 μm or more, from the viewpoint of effectively utilizing the space around the periphery of the screen and its vicinity.

The upper limit of W ₁ is not particularly limited, and may be set according to the size or screen size of the image display device. W ₁ is, for example, preferably 10% or less of the length of the diagonal of the optical film, more preferably 5% or less, and still more preferably 1% or less. Moreover, W ₁ is preferably 50 mm or less, more preferably 10 mm or less, still more preferably 5 mm or less, and still more preferably 1 mm or less. From the viewpoint of preventing peeling by reliably bonding the optical film 11 and the front surface transparent member etc. with the first adhesive layer 21, W1 is preferable to avoid the _first adhesion between the constituent members of the image display device and the first. The physical interference of the agent layer is as small as possible.

The area of the optical film 11 is not particularly limited, but is generally about 5 to 25000 cm ² . When the optical film 11 is rectangular, the length of the diagonal is about 3-250 cm. In particular, in a medium-sized or small-sized image display device having an area of 2000 cm ² or less, the effect of saving space obtained by the configuration of the present invention is large.

When the optical film 11 is rectangular, it may be a rectangle having long sides and short sides, or may be a square with four sides having the same length. The length of the long side of the rectangle is generally less than 10 times the length of the short side, and may be less than 5 times, less than 3 times, or less than 2 times. When the optical film is an optically anisotropic film such as a polarizing plate or retardation film, the direction of the optical axis such as the absorption axis or the retardation axis may be parallel or perpendicular to the extending direction of the side of the rectangle, or may be parallel to the side of the rectangle. The extension direction is at a specific angle. When the optical film is a laminate of a plurality of films, the arrangement of the optical axes of the respective films is not particularly limited, and may be parallel or orthogonal, or may form a specific angle. For example, in the case of a circular polarizer, the polarizer and the quarter-wave plate are laminated so that the angle formed by the direction of the absorption axis of the polarizer and the direction of the retardation axis of the quarter-wave plate becomes 45°.

In the optical film with double-sided adhesive of the first embodiment, a part of the area along the periphery of the optical film 11 is a non-adhesive area, and in other areas, a first adhesive layer 21 is attached to the periphery of the optical film 11, The end of the first main surface is covered by the first adhesive layer 21 . The area where the physical interference between the adhesive and the components of the image display device should be avoided is set as the non-bonding area, and the other areas are the bonding areas where the adhesive layer 21 is also provided on the periphery of the optical film 11, so that the adhesive can be reliably used. The agent layer 21 sticks the optical film 11 and the cover glass etc., and prevents peeling.

(protective sheet) 2 is a cross-sectional view of an optical film 451 having a double-sided adhesive with a protective sheet on the adhesive layer. The first protection sheet 41 is releasably attached to the first adhesive layer 21 , and the second protection sheet 42 is releasably attached to the second adhesive layer 22 . If the protective sheet is temporarily adhered to the adhesive layer in this way, the exposed surfaces of the adhesive layers 21 and 22 can be protected until the optical film 11 and the adherend are bonded together.

As a constituent material of the protective sheets 41 and 42, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films are preferable. The thickness of the protective sheets 41 and 42 is usually 5 to 200 μm, preferably about 10 to 150 μm. The protective sheet can also be subjected to a peeling treatment by a polysiloxane-based release agent or the like on the bonding surface with the adhesive.

(Formation of the adhesive layer and the non-bonded area on the optical film) As a method of providing the first adhesive layer 21 and the second adhesive layer 22 on the optical film 11 , the method of applying the adhesive composition to a release treatment sheet or the like to form an adhesive layer, and then transferring the adhesive layer onto the optical film 11 can be exemplified. method, a method of coating the adhesive composition on the optical film 11, and the like. The adhesive composition after coating may be subjected to drying removal of the solvent, cross-linking treatment, hardening treatment, etc. as necessary.

As a method of locally providing the non-adhesion region 2x on the main surface of the optical film 11, there can be mentioned a method of controlling the attaching region of the first adhesive layer 21 on the optical film 11, attaching to the entire surface of the main surface of the optical film A method of removing the adhesive layer in a specific area after the first adhesive layer 21 . The non-bonding area can also be formed by the bonding area being smaller than the adhesive layer of the optical film on the optical film adjusted to the size for bonding with the image display device. Moreover, the specific area|region of the adhesive bond layer provided in the whole surface on the optical film adjusted to the size for lamination|attachment with an image display apparatus can also be removed, and a non-adhesion area|region can also be formed.

Thomson knives, circular knives, disc knives, laser cutters, etc. can also be used to cut the optical film with a double-sided adhesive that is larger in size than the optical film used for lamination with image display devices to a specific size. size. An optical film with a double-sided adhesive having a non-bonding area 2x on the periphery of the optical film can also be produced by disposing an area without the first adhesive layer on the optical film and cutting the area. For example, when cutting an optical film with a long double-sided adhesive to a specific size, as long as the area where the first adhesive layer is not provided on the optical film is cut, a non-adhesive film along the cutting line can be obtained. Optical film with adhesive on both sides of the area. A plurality of films can be cut from a large-sized single film (mother substrate), or a specific-sized film can be further cut to produce an optical film with a double-sided adhesive with a non-bonded area on the periphery.

In the non-bonded area 2x, the protective sheet 41 preferably covers the first main surface of the adhesive layer 21. The position of the end surface 41e of the protective sheet 41 may be aligned with the end surface 21e of the adhesive layer 21 and may also be aligned with the end surface 11e of the optical film 11 . The end surface 41e of the protective sheet 41 may be located between the end surface 21e of the adhesive layer 21 and the end surface 11e of the optical film 11 , or may be located outside of the end surface 11e of the optical film 11 .

If a region without the first adhesive layer is provided on the optical film, and the entire surface of the region with the adhesive layer and the region without the adhesive is covered by the protective sheet, and cut into a single piece size, as As shown in FIG. 2 , in both the bonding region and the non-bonding region, the positions of the end face 11e of the optical film 11 and the end face 41e of the protective sheet 41 are aligned. In the non-bonding region 2x, as long as the end surface 21e of the adhesive layer 21 is present on the inner side than the end surface 11e of the optical film 11 and the end surface 41e of the protective sheet 41, the paste contamination or paste of the end surface 21e of the adhesive layer can be suppressed. agent deficiency.

As long as the first adhesive layer is attached to the surface of the optical film in the adhering region of the peripheral edge of the optical film, the main surface of the optical film is not exposed. In the adhering area, the position of the end face of the protective sheet 41 can be aligned with the position of the end face of the first adhesive layer 21 , and the end face of the protective sheet 41 can also be positioned outside the end face of the first adhesive layer 21 .

As shown in the optical film 53 with adhesive on both sides as shown in FIG. 3 , the end face 21 c is located at the center of the thickness direction of the first adhesive layer 21 compared to the end face of the optical film 11 and the end face of the first protective sheet 41 . more inward. In the adhering region, since the end face 21c of the central part in the thickness direction of the adhesive layer 21 is present on the inner side of the end face of the optical film 11, it is possible to suppress the transportation, lamination, etc. of the optical film with double-sided adhesive. Paste contamination or paste defect on the process line.

For example, by cutting the optical film with the adhesive on both sides under pressure from the main surface side, at the interface with the optical film, the position of the end face of the adhesive layer coincides with the position of the end face of the optical film, and at the interface with the optical film The central part in the thickness direction of the adhesive layer can make the end face of the adhesive layer located inside. When pressure is applied to the optical film with the double-sided adhesive in the state where the protective sheets 41 and 42 are attached to the adhesive layers 21 and 22, the adhesive layer is elastically deformed, and the adhesive layer becomes an adhesive in the central part in the thickness direction. The state in which the end of the layer protrudes from the end of the optical film. If the adhesive layers 21 and 22 are cut together with the optical film 11 and the protective sheets 41 and 42 in this state, the positions of the end faces of the optical film 11 and the end faces of the protective sheets 41 and 42 and the adhesive layers 21 and 22 The position of the end face is aligned. If the pressure is released after cutting, the end face of the central portion of the adhesive layer in the thickness direction retreats to the inner side of the end face of the optical film 11 due to the deformation of the adhesive, and the adhesive layer as shown in FIG. 3 is obtained. The end face of the central part in the thickness direction is located on the inner side of the double-sided adhesive optical film.

When the end face of the central portion in the thickness direction of the first adhesive layer 21 is located more inward than the end face of the optical film 11 in the adhering region, the distance between the end face of the optical film 11 and the central portion in the thickness direction of the first adhesive layer is The distance W ₂ between the end faces is, for example, about 5 μm to 300 μm. W ₂ is more preferably about 10 μm to 100 μm, and more preferably about 15 μm to 70 μm, from the viewpoint of both suppressing the sticking out of the adhesive from the end face and the adhesiveness of the end portion. W ₂ and W ₁ may be the same or different. Generally, W ₂ <W ₁ .

The optical film 51 with double-sided adhesive shown in FIG. ₁ is provided with a non-bonding area 2x along one short side 11a1 of the four sides of the rectangular optical film 11 . The non-bonding area can be arranged on more than two sides of the rectangle, and can also be arranged on the long side of the rectangle. In the non-bonded area, the end face of the first adhesive layer does not need to extend parallel to the edge of the optical film. For example, the non-bonded region may have a portion whose width becomes smaller from the end of the side of the rectangle (the vertex of the rectangle) toward the center side of the side. The non-adjacent area need not be located along the full length of the edge. For example, only a part of the side of the rectangle or the vertex of the rectangle may be provided with a non-contact area.

The shape of the optical film is not limited to a rectangle, and may be an appropriate shape according to the shape or size of the screen of the image display device. For example, the top view shape of the optical film may also be a polygon such as a triangle, a rhombus, a parallelogram, a trapezoid, a pentagon, and a hexagon, a circle, an ellipse, a star, and the like.

<Image display device> FIG. 4 is a cross-sectional view of an image display device 101 fabricated using an optical film 51 with a double-sided adhesive. In the image display device 101 , an optical film 11 is disposed on the image display unit 60 , and a cover glass 71 with a touch sensor is disposed on the visible side of the optical film 11 . The optical film 11 and the image display unit 60 are bonded via the second adhesive layer 22 , and the optical film 11 and the cover glass 71 are bonded via the first adhesive layer 21 . The image display unit 60 is, for example, a liquid crystal unit, an organic EL (OLED), or a micro LED (Light Emitting Diode). In place of the cover glass 71, a transparent resin plate including a transparent resin material such as acrylic resin may be used.

A flexible printed wiring board (FPC) 91 as an electrical connection member is connected to a touch sensor (not shown) provided on the surface facing the optical film 11 near the end of the cover glass 71 . The FPC 91 is bent so as to wrap around to the back side of the image display unit 60 .

FIG. 5 is a cross-sectional view of an image display device 501 using a previous double-sided adhesive optical film 551 . The image display device 501 has a structure similar to that of the image display device 101 in FIG. 4 , but the adhesive layer 521 between the optical film 11 and the cover glass 571 is disposed on the entire surface of the optical film.

In the image display device 501, along the entire circumference of the periphery of the optical film 11, the positions of the end face 11e and the end face 521e of the adhesive layer 521 are aligned, and the entire space between the optical film 11 and the cover glass 571 is covered by the adhesive layer 521. cover. Since there is no gap between the optical film 11 and the cover glass 571 , the contact point 507 a between the touch sensor and the FPC 591 is disposed outside the end surface 11 e of the optical film 11 . Since a space for accommodating electrical connection components such as FPC must be secured outside the display area of the screen, it is difficult to reduce the width of the frame area around the screen.

On the other hand, in the image display device 101 of FIG. 4 using the optical film 51 with the double-sided adhesive of the present invention, by arranging the FPC 91 in the space of the non-bonding area 2x along the side 11a ₁ , the optical A contact 7a between the touch sensor and the FPC 91 is disposed on the end surface 11e of the film 11, or on the inner side of the end surface 11e. In this way, the non-adhesive region 2x without the first adhesive layer 21 is provided on the optical film 11, and the FPC or the like is arranged in the gap portion, so as to effectively utilize the space around the periphery of the screen and its vicinity, thereby realizing the narrowing of the edge. .

As described above, the end face 21c of the central portion in the thickness direction of the first adhesive layer 21 is located more inward than the end face of the optical film 11 in the bonding region of the optical film periphery (see FIG. 3 ). In this form, even when the distance W ₂ between the end face 21 c of the first adhesive layer 21 and the end face of the optical film in the bonding area is large, the attachment interface of the optical film 11 and the attachment interface of the protective sheet 41 are , the positions of the end face of the first adhesive layer and the end face of the optical film 11 and the protective sheet 41 are also consistent. Therefore, even when W ₂ is large, it is difficult to avoid physical interference between the FPC or the like and the adhesive layer in the bonding region, thereby achieving a narrow edge.

The use form of the optical film 51 having a double-sided adhesive with a non-bonded region on one side is not limited to the structure shown in FIG. 4 , and can also be applied to image display devices having other structures. For example, as in the image display device 102 shown in FIG. 6 , the cover glass 72 disposed on the surface may be provided with decorative printing 72 a on the periphery of the screen on the surface facing the optical film 11 . In this embodiment, the FPC 91 is arranged in the space of the non-contact area 2x outside the decorative printing 72a of the cover glass 71, and the contact 7a between the touch sensor and the FPC is arranged.

Alternatively, as in the image display device 103 shown in FIG. 7 , the optical film 11 and the touch sensor 73 can also be attached through the first adhesive layer 21 , and on it, through another adhesive layer 29 . Fit the cover glass 79.

In the image display device, the first adhesive layer 21 side of the double-sided adhesive optical film does not need to be arranged on the visible side, but the first adhesive layer 21 can also be arranged on the image display unit side. For example, in the image display device 104 shown in FIG. 8 , a polarizing plate 17 having a touch sensor is attached to the image display unit 60 through the first adhesive layer 21 , and the polarizing plate 17 is attached to the polarizing plate 17 . On the top, a cover glass 79 is attached via the second adhesive layer 22 . In the vicinity of the end of the polarizing plate 17 serving as an optical film, an FPC 91 is connected to the touch sensor disposed on the surface opposite to the image display unit 60 . In this embodiment, the space can be effectively used by setting the area where the FPC contacts 7a between the image display unit 60 and the polarizing plate 17 serving as the optical film are provided as the non-bonding area 2x.

<Modification of 1st Embodiment> As mentioned above, the position where the non-adhesion area|region is provided in the 1st main surface of an optical film is not limited to the short side of a rectangle. For example, as shown in FIG. 9 , the optical film 56 with double-sided adhesive may have non-bonding regions 2x on the first principal surface of the optical film 11 on the two long sides 11a ₂ and 11a ₄ of the rectangle.

FIG. 10 is a schematic perspective view of an image display device 106 produced by using the optical film 56 with the adhesive on both sides of FIG. 9 . The image display device 106 is provided with a cover glass 74 on the visible side surface, and the end of the cover glass 74 is combined with the casing 84 . The long side 74a of the cover glass 74 extending in the x direction is curved. As long as the curved portion 74a of the cover glass 74 is disposed on the non-bonding region 2x of the double-sided adhesive optical film, the physical interference between the first adhesive layer 21 and the cover glass 74 can be avoided, and the device can be effectively utilized inner space.

In FIG. 10 , the long side 74a of the cover glass 74 has a shape that is chamfered into a curved shape, but the long side of the cover glass 74 may be chamfered into a flat shape. In addition, the apex portion of the cover glass may be chamfered in a flat or curved shape. The shape of the outer surface and the inner surface of a front transparent plate such as a cover glass or a chamfered portion of a casing may be the same or different. In addition, the casing can also be arranged in the non-bonded area, so as to avoid the physical interference between the adhesive layer and the casing.

11 and 12 are plan views of the first principal surface side of the optical film of the double-sided adhesive of other embodiments, respectively. The optical film 57A of the double-sided adhesive shown in FIG. 11 has arcuate non-bonding regions 2× ₁ at the four vertices of the rectangle. For example, if the optical film 57A of the double-sided adhesive is used in an image display device having a transparent surface plate or a housing before forming a shape having a rectangular apex with a curvature, the curved shape near the apex of the display area can be avoided Part of the physical interference with the first adhesive layer 21 effectively utilizes the space within the device.

The optical film 57B with double-sided adhesive shown in FIG. 12 has arcuate non-bonding regions 2x ₁ at both ends of one short side 11a ₃ and non-bonding regions 2x along the entire length of the other short side 11a _{1 2} . As shown in FIG. 12 , the non-bonding regions _2x2 provided along the short side 11a ₁ may also be linear along the entire length of the short side 11a ₁ , and the corners are not curved. In this way, the non-bonding area provided along the edge can be used to avoid physical interference with the front surface transparent member or the casing, and can also be used to avoid physical interference with constituent members such as FPC.

FIG. 13 is a plan view of the first principal surface side of the optical film 58 with a double-sided adhesive having a non-bonding region at one of the sides. The optical film 58 with double-sided adhesive is provided with a cut-shaped non-bonding area _2x3 on the short side 11a1 _of the rectangle.

14 is a cross-sectional view of an image display device 108 fabricated using an optical film 58 with a double-sided adhesive. In the image display device 108 , a lead wire 98 is provided in order to ground the image display unit 60 and the optical film 11 . In the non-bonding area _2x3 , the first adhesive layer 21 is not provided on the optical film 11 and the optical film 11 is exposed, so the grounding point 8a of the wire 98 can be provided on the first main surface of the optical film 11. The wires 98 can be formed by metal wires, metal pastes, or the like. In order to prevent oxidation of the metal constituting the lead 98, etc., an insulating layer such as a resin coating layer may be provided on the surface of the lead.

As an example of disposing the constituent members of the image display device in the non-adhesive area on the first main surface of the optical film, an example of disposing the contact point with the FPC in the non-adhesive area, disposing the front surface transparent plate in the non-adhesive area, or The example of the housing and the example of providing the contact with the lead wire are not limited to the configuration of the image display device, and the members arranged in the non-bonding area are not particularly limited. The member disposed in the non-bonding area can be any conductive material or insulating material. For example, a conductive material or a resin material can also be provided so as to cover the non-bonding region on the first main surface of the optical film and the side surface of the optical film.

The conductive material or resin material can also be provided so as to further cover the surface of the image display panel. For example, by providing a resin layer so as to cover the surface of the organic EL unit and the side surface of the optical film, and sealing the organic EL unit, deterioration of the organic EL unit can be suppressed.

The image display unit need not be flat. For example, the entire surface of the image display unit may be curved, or the end of the image display unit may be curved. When the end portion of the image display unit is curved, the non-bonded area may also be included in the curved portion. The conductive material or resin material can also be provided so as to cover the surface of the image display panel. In addition, the image display unit may be in the shape of a curved surface in a non-display part such as a connection area with the FPC.

In the optical film with the adhesive on both sides, the second adhesive layer 22 can also be provided in a manner of covering the entire surface of the second main surface of the optical film. By not having a non-bonding region along the entire circumference of the perimeter of the second main surface, the image display unit 60 and the like and the optical film 11 can be surely bonded, and peeling from the edge can be prevented. In addition to disposing the non-adhering area on the first main surface of the optical film, the non-adhering area may also be disposed on the second main surface, so as to avoid physical interference with the constituent members of the image display device.

[Second Embodiment] The optical film of the double-sided adhesive of the second embodiment has an area (non-adhesive area) where the first adhesive layer is not attached and the optical film is exposed along the entire circumference of the periphery of the first main surface of the optical film. In this embodiment, the non-bonded region may also have regions with different widths along the periphery of the first main surface of the optical film. The optical film of the double-sided adhesive of the second embodiment has a non-bonding region along the entire circumference of the peripheral edge of the first main surface of the optical film 11 , and there is no bonding region on the peripheral edge of the first main surface of the optical film 11 . Except for this, the structure of the optical film of the double-sided adhesive of 2nd Embodiment is the same as that of 1st Embodiment.

An example of the optical film of the double-sided adhesive of the second embodiment is shown in FIG. 15 . FIG. 15A is a top view of the first principal surface side of the double-sided adhesive optical film 251, and FIG. 15B is a cross-sectional view taken along the line B1-B2. The optical film of the double-sided adhesive of 2nd Embodiment is provided with the 1st adhesive bond layer 21 on one side of the optical film 11 similarly to 1st Embodiment, and is provided with the 2nd adhesive bond layer 22 on the other side. A protective sheet (not shown) may also be temporarily adhered to the surfaces of the adhesive layers 21 and 22 .

The width W ₁₁ of the non-bonding area 2× ₄₁ along one short side 11a ₁ of the double-sided adhesive optical film 251 is different from the width W ₁₃ of the non-bonding area 2× ₄₃ along the other short side 11a ₃ . For example, when forming an image display device, the space of the non-bonding area 2× ₄₁ becomes the area for connecting the FPC to the touch sensor, and the space of the non-bonding area 2× ₄₃ becomes the cover glass for avoiding the curved shape with the end. or areas of physical interference such as shells. The non-bonding regions along the rectangular long side 11a ₂ and the long side 11a ₄ of the optical film 11 also serve as regions for avoiding physical interference with the cover glass, the housing, and the like. In this way, by adjusting the width of the non-bonding area according to the object to be avoided physical interference, the effective use of the space and the bonding reliability by the first adhesive layer can be taken into account.

The ratio of the maximum value to the minimum value of the width of the non-bonded region is not particularly limited. The maximum value of the width of the non-bonded region is, for example, 1.1 times or more the minimum value of the width of the non-bonded region. The maximum value of the width of the non-bonded area may be 1.3 times or more, 1.5 times or more, 2 times or more, or 3 times or more of the minimum value of the width of the non-bonded area.

FIG. 16 is a plan view of the first principal surface side of the optical film 253 with double-sided adhesive. In the optical film 253 with double-sided adhesive, the width of the non-bonded area 2× ₅ is approximately equal to the central portion of the side of the rectangle. In the vicinity of the vertex of the rectangle, the non-bonding area 2× ₅ has a flat shape with a radian, and the width of the non-bonding area decreases from the end of the side of the rectangle toward the center side. If an optical film 253 with a double-sided adhesive with a non-bonded area of 2× ₅ in such a shape is used, the entire circumference of the periphery of the display area can be used to avoid contact with the image display device components such as cover glass or housing. physical interference.

[third embodiment] The non-adhesion area of the optical film with the double-sided adhesive can also be provided in the area other than the peripheral edge of the optical film. The optical film of the double-sided adhesive of the third embodiment has an area (non-adhesive area) where the first adhesive layer is not attached and the optical film is exposed on the inner side of the peripheral edge of the first main surface of the optical film. Except for this, the structure of the optical film of the double-sided adhesive of 3rd Embodiment is the same as that of 1st Embodiment and 2nd Embodiment. Similar to the first embodiment and the second embodiment, the optical film of the double-sided adhesive of the third embodiment may have a protective sheet (not shown) temporarily adhered to the surfaces of the adhesive layers 21 and 22 .

An example of the optical film of the double-sided adhesive of the third embodiment is shown in FIG. 17 . FIG. 17 is a plan view of the first principal surface side of the optical film 351 with double-sided adhesive. FIG. 18 is a yz cross-sectional view (a cross-sectional view along the short-side direction of FIG. 17 ) of the image display device 109 produced by using the optical film 351 with a double-sided adhesive.

The optical film 351 with double-sided adhesive has a non-bonding area 2× ₆ extending parallel to the long side on the inner side of the long side 11a ₄ . In the image display device 109 , the optical film 11 is disposed on the image display unit 60 , and a cover glass 372 is disposed on the visible side of the optical film 11 . The optical film 11 and the image display unit 60 are bonded via the second adhesive layer 22 , and the optical film 11 and the cover glass 372 are bonded via the first adhesive layer 21 . On the cover glass 372, decorative printing is applied to the surface opposite to the optical film 11, so as to overlap the raised portion 372a generated by the decorative printing on the non-bonding area _2x6 of the optical film 351 with double-sided adhesive configuration.

In the image display device 109, the adhesive layer is not provided directly under the raised portion 372a caused by decorative printing, and the adhesive is not compressively deformed by the raised portion. Therefore, it is possible to suppress the peeling of the adhesive from the protuberance and the display unevenness due to the compressive stress of the adhesive.

The optical film of the double-sided adhesive of FIG. 17 also corresponds to the first embodiment because it has non-bonding regions 2× ₆ on the short side 11a ₁ and the short side 11a ₃ of the rectangle. Also like the optical film 352 with double-sided adhesive in the top view shown in FIG. 19 , the optical film with double-sided adhesive in the third embodiment does not have a non-bonded area on the periphery of the optical film 11 , but only on the periphery There is a non-adjacent area 2x ₇ on the inner side.

The optical film with a double-sided adhesive may also have a non-adhered region in both the region along the periphery of the first main surface of the optical film and the region inside the periphery. For example, as shown in the top view in FIG. 20 , the optical film 353 with double-sided adhesive may have a non-bonding area 2x along the short side 11a ₁ of the rectangle and a non-bonding area 2x ₆ on the inner side of the long side 11a ₄ .

The non-bonding area existing on the periphery of the first main surface and the non-bonding area existing on the inner side of the periphery may be connected to be integrated, or may not be connected. For example, the optical film 355 with double-sided adhesive as shown in the top view of FIG. 21 may also have non-bonding regions 2× ₈ extending parallel to one side 11a ₁ of the rectangle and disposed at both ends of the side 11a ₃ The non-adjacent area near the vertex of 2x ₁ .

As described above, the optical film with double-sided adhesive of the present invention is provided with an adhesive layer on both sides of the optical film, and has an area where the optical film is exposed without the adhesive layer on at least one side. By the existence of the non-bonded region, a void is formed between the optical film and the adherend when the image display device is formed. By arranging the constituent members of the image display device in the space, physical interference with the adhesive can be avoided, the space can be effectively utilized, and the image display device can be saved in space and narrowed.

2x: non-adjacent area 2x ₁ : non-adjacent area 2x ₂ : non-adjacent area 2x ₃ : non-adjacent area 2x ₅ : non-adjacent area 2x ₆ : non-adjacent area 2x ₇ : non-adjacent area 2x ₈ : non-adjacent area 2x ₄₁ : Non-bonded area _2x43 : Non-bonded area 7a: Contact 8a: Ground point 11: Optical film 11a ₁ : Side 11a ₂ : Side 11a ₃ : Side 11a ₄ : Side 11e: End surface 17: Polarizing plate 21: Adhesive layer 21c : End face 21e : End face 22 : Adhesive layer 29 : Adhesive layer 41 : Protective sheet 41e : End face 42 : Protective sheet 51 : Optical film with adhesive 53 : Optical film with adhesive 56 : Optical film with adhesive 57A: Optical film with adhesive 57B: Optical film with adhesive 58: Optical film with adhesive 60: Image display unit 71: Cover glass with touch sensor 72: With touch sensor Cover glass 72a: Bump (printed part) 73: Touch sensor 74: Cover glass 74a: Long side 79: Cover glass 84: Case 91: Flexible printed wiring board 98: Lead wire 101: Image display device 102: Image Display Device 103: Image Display Device 104: Image Display Device 106: Image Display Device 108: Image Display Device 109: Image Display Device 251: Adhesive-Adhering Optical Film 253: Adhesive-Adhering Optical Film 351: optical film with adhesive 352: optical film with adhesive 353: optical film with adhesive 355: optical film with adhesive 372: cover glass with touch sensor 372a: raised part (printed part ) 451: Optical film with adhesive 501: Image display device 507a: Contact 521: Adhesive layer 521e: End face 551: Optical film with adhesive 571: Cover glass 591: Flexible printed wiring board W ₁ : Width W ₂ : Distance W ₁₁ : Width W ₁₃ : Width

1A is a top view of the optical film with double-sided adhesive, and B is a cross-sectional view of the optical film with double-sided adhesive. 2 is a cross-sectional view of an optical film with a double-sided adhesive with a protective sheet provided on the adhesive sheet. 3 is a cross-sectional view of an optical film with a double-sided adhesive with a protective sheet provided on the adhesive sheet. FIG. 4 is a cross-sectional view of the image display device. FIG. 5 is a cross-sectional view of an image display device of the prior art. 6 is a cross-sectional view of an image display device. 7 is a cross-sectional view of an image display device. 8 is a cross-sectional view of an image display device. Figure 9 is a top view of an optical film with a double-sided adhesive. FIG. 10 is a schematic perspective view of an image display device. Figure 11 is a top view of an optical film with a double-sided adhesive. Figure 12 is a top view of an optical film with a double-sided adhesive. Figure 13 is a top view of an optical film with a double-sided adhesive. FIG. 14 is a cross-sectional view of an image display device. 15A is a top view of the optical film with double-sided adhesive, and B is a cross-sectional view of the optical film with double-sided adhesive. Figure 16 is a top view of an optical film with a double-sided adhesive. Figure 17 is a top view of an optical film with a double-sided adhesive. FIG. 18 is a cross-sectional view of an image display device. Figure 19 is a top view of an optical film with a double-sided adhesive. Figure 20 is a top view of an optical film with a double-sided adhesive. Figure 21 is a top view of an optical film with a double-sided adhesive.

2x: non-joined area

7a: Contact

11: Optical film

21: Adhesive layer

22: Adhesive layer

51: Optical film with adhesive

60: Image display unit

71: Cover glass with touch sensor

91: Flexible Printed Wiring Board

101: Image display device

Claims (16)

An optical film with a double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and an optical film disposed on the optical film a second adhesive layer on the second main surface of the film, The above-mentioned optical film is rectangular, Along the periphery of the first main surface of the above-mentioned optical film, there is a non-bonded area where the above-mentioned first adhesive layer is not provided and the above-mentioned optical film is exposed, and an adhesive area where the above-mentioned first adhesive layer is attached on the above-mentioned optical film, and The non-bonded region is provided along at least one side of the rectangle, and the bonded region is provided along the entire length of at least one side of the rectangle. The optical film with a double-sided adhesive according to claim 1, wherein the non-bonded region has a portion whose width becomes smaller from the end of the side of the rectangle toward the center side. An optical film with a double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and an optical film disposed on the optical film a second adhesive layer on the second main surface of the film, The above-mentioned optical film is rectangular, Along the periphery of the first main surface of the above-mentioned optical film, there is a non-bonded area where the above-mentioned first adhesive layer is not provided and the above-mentioned optical film is exposed, and an adhesive area where the above-mentioned first adhesive layer is attached on the above-mentioned optical film, and The above-mentioned non-bonded region has a portion whose width becomes smaller from the end of the side of the rectangle toward the center side. The optical film with a double-sided adhesive according to any one of claims 1 to 3, wherein in the above-mentioned bonding region, with respect to the above-mentioned first adhesive layer, At the interface with the above-mentioned optical film, the position of the end face of the adhesive layer is consistent with the position of the end face of the above-mentioned optical film, and In the center part of the thickness direction of the said 1st adhesive bond layer, the end surface of an adhesive bond layer is located in the inner side rather than the end surface of the said optical film. An optical film with a double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and an optical film disposed on the optical film a second adhesive layer on the second main surface of the film, The above-mentioned optical film is rectangular, Along the entire circumference of the peripheral edge of the first main surface of the optical film, there is a non-bonded region where the first adhesive layer is not provided and the optical film is exposed, and The above-mentioned non-bonded region has a portion whose width becomes smaller from the end of the side of the rectangle toward the center side. The optical film with double-sided adhesive according to claim 5, wherein the width of the non-bonded region in one side of the rectangle is different from the width of the non-bonded region in the other side of the rectangle. The optical film with a double-sided adhesive according to any one of claims 1 to 3, 5 and 6, wherein in the non-adhesive region, the end face of the optical film and the end face of the first adhesive layer have lines along the A portion of the peripheral edge of the optical film that extends in parallel. The optical film with a double-sided adhesive according to any one of claims 1 to 3, 5 and 6, wherein the second adhesive layer is provided along the entire circumference of the periphery of the second main surface of the optical film, There is no region where the second main surface of the optical film is exposed. An optical film with a double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and an optical film disposed on the optical film a second adhesive layer on the second main surface of the film, Along the entire circumference of the peripheral edge of the first main surface of the optical film, there is a non-bonding region where the first adhesive layer is not provided and the optical film is exposed, Along the periphery of the first main surface of the above-mentioned optical film, there are areas with different widths of the above-mentioned non-bonded areas, and The said 2nd adhesive bond layer is provided along the whole periphery of the periphery of the 2nd main surface of the said optical film, and the area|region where the 2nd main surface of the said optical film is exposed does not exist. The optical film with a double-sided adhesive as claimed in claim 9, wherein the optical film is rectangular, and The width of the non-bonded region in one side of the rectangle is different from the width of the non-bonded region in the other side of the rectangle. The optical film with a double-sided adhesive as claimed in claim 9 or 10, wherein in the non-adhesive region, the end face of the optical film and the end face of the first adhesive layer have a surface extending parallel to the periphery of the optical film. part. An optical film with a double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and an optical film disposed on the optical film a second adhesive layer on the second main surface of the film, On the inner side of the peripheral edge of the first main surface of the optical film, there is a non-bonding region where the first adhesive layer is not provided and the optical film is exposed, and The said 2nd adhesive bond layer is provided along the whole periphery of the periphery of the 2nd main surface of the said optical film, and the area|region where the 2nd main surface of the said optical film is exposed does not exist. The optical film with a double-sided adhesive according to any one of claims 1 to 3, 5, 6, 9, 10 and 12, which has the above-mentioned non-bonded area with a width of 10 μm or more. The optical film with a double-sided adhesive according to any one of claims 1 to 3, 5, 6, 9, 10 and 12, wherein the optical film comprises a polarizing plate. The optical film with double-sided adhesive according to any one of claims 1 to 3, 5, 6, 9, 10 and 12, wherein a first protective sheet is releasably attached to the first adhesive layer, A second protective sheet is releasably attached to the second adhesive layer. The optical film with double-sided adhesive according to claim 15, wherein along the entire circumference of the peripheral edge of the optical film, the position of the end face of the optical film and the end face of the first protective sheet is aligned.

Images