JP2010072471A - Transparent adhesive sheet, image display apparatus comprising the same, and method for producing the image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent adhesive sheet, which does not cause uneven display, blister formation, and detachment on a display unit of an image display apparatus, and a method for producing the image display apparatus by using the sheet. <P>SOLUTION: A surface protective layer 4 of the image display apparatus 10 or a touch panel, and a surface of an image display unit 1 are bonded together using the transparent adhesive sheet 3. The transparent adhesive sheet has a storage elastic modulus of ≤1.0×10<SP>4</SP>Pa and ≥1.0×10<SP>3</SP>Pa at 1 Hz and 80°C, wherein the sheet comprises (A) an alicyclic hydrocarbon resin, (B) an amorphous saturated polyolefm resin, (C) an acrylic group-containing resin, and (D) an initiator that triggers the reaction of the resins, and wherein, based on the amount of 100 parts by mass of (A) component, the amount of (B) component is 10-200 parts by mass, the amount of (C) component is 10-200 parts by mass, and the amount of (D) component is 0.1-20 parts by mass. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present disclosure relates to a transparent adhesive sheet and an image display device including the same.

  In recent years, the surface protective layer or touch panel in the image display device has a refractive index that is higher than that of air in the gap between the surface protective layer or the touch panel and the display surface of the image display unit, or between the surface protective layer and the touch panel. In addition, a method has been proposed in which the transparency is improved by replacing with a transparent material close to the display surface of the image display unit and the decrease in luminance and contrast of the image display device is suppressed. Examples of the transparent substance include transparent polymer materials such as a transparent resin sheet, a pressure-sensitive adhesive (pressure-sensitive adhesive), and a curable adhesive (for example, silicone gel).

  Patent Document 1 (Japanese Patent Application Laid-Open No. 09-197387) discloses a volatile liquid between a transparent resin sheet and one or both of a liquid crystal display panel and a transparent protective plate via a transparent resin sheet made of a plasticizer-containing polymer. In a state where the liquid crystal display device is disposed, a liquid crystal display device manufacturing method is described in which the viewing side of the liquid crystal display panel and the transparent protective plate are in close contact with each other via a transparent resin sheet as a transparent polymer material.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 06-59253) discloses a method of manufacturing a liquid crystal display device using a reaction curable silicone gel which is a colorless transparent elastic resin as a transparent polymer material between a liquid crystal display panel and a glass plate. Is described. The colorless and transparent elastic resin is fixed in a liquid crystal display panel and a glass plate by being injected in a liquid state and then cured.

  Patent Document 3 (Japanese Patent Laid-Open No. 03-204616) describes a liquid crystal display in which a transparent polymer material is filled between a liquid crystal display element and a protective plate. As the transparent polymer material, a material in which an unsaturated polyester is dissolved in a polymerizable monomer is used, which is solidified after being injected into a gap between the liquid crystal display element and the protective plate.

Patent Document 4 (Japanese Patent Application Laid-Open No. 2007-31506) discloses that CH ₂ = CR ¹ COOR ² (wherein R ¹ is a hydrogen atom or a methyl group, and R ² is a hydroxyl group with respect to 100 parts by weight of alkyl (meth) acrylate. (Meth) acrylic polymer (A) containing 0.01 to 5 parts by weight of a hydroxyl group-containing (meth) acrylate represented by a C 4-12 hydroxyalkyl group having at least one carbon atom) The adhesive composition for optical members characterized by containing 0.02 to 2 parts by weight of peroxide with respect to 100 parts by weight is described.

JP 09-197387 A Japanese Patent Laid-Open No. 06-59253 Japanese Patent Laid-Open No. 03-204616 JP 2007-31506 A

Transparent materials include adhesives, silicone gels, and pressure-sensitive adhesives, but adhesives are a problem in that they are a liquid handling process and the manufacturing process is complicated, and silicone gel has a low adhesive strength. There is a problem with long-term reliability. On the other hand, since the adhesive can solve these problems, it is effective for a structure in which the image display device and the protective layer cover are directly bonded. However, conventional acrylic pressure-sensitive adhesives made of acrylic acid alkyl ester and acrylic acid may cause unevenness in the display device when the thickness of the pressure-sensitive adhesive is reduced. Occurrence and peeling of the adhesive may occur.
Therefore, in particular, when the surface protective layer in the image display device has an uneven shape, and an adhesive sheet is applied to the uneven surface, or an image display provided with a layer having an uneven shape (for example, a polarizing plate). When a pressure-sensitive adhesive sheet is applied to the display surface of the unit, it is desired that this display unevenness does not occur even under a condition where the adhesive thickness is 100 μm or less. Further, in addition to the occurrence of display unevenness, the surface protective layer in the image display device, the display surface of the image display unit, or the touch panel (hereinafter sometimes referred to as “adhered body”) even when placed in a high temperature and high humidity state. There is a need for a transparent pressure-sensitive adhesive sheet that does not generate bubbles or peel off at the interface thereof and does not whiten.

According to certain aspects of the present disclosure,
(1) A pressure-sensitive adhesive sheet having a storage elastic modulus of 1.0 × 10 ⁴ Pa or less and 1.0 × 10 ³ Pa or more at 1 Hz and 80 ° C., and (A) an alicyclic hydrocarbon resin (B) a non-crystalline saturated polyolefin resin, (C) an acrylic group-containing resin, and (D) an initiator that causes the reaction of the resin, and (B) component based on 100 parts by mass of component (A) The amount of is 10 to 200 parts by weight, the amount of component (C) is 10 to 200 parts by weight, and the amount of component (D) is 0.1 to 20 parts by weight. The process of
(2) The process of sticking the said adhesive sheet on a surface protective layer or a touchscreen,
(3) A step of attaching the surface opposite to the adhesive sheet to which the surface protective layer or the touch panel is attached to the display surface of the image display unit,
(4) a step of curing the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet,
A method for manufacturing an image display device including the above is provided.

According to still another aspect of the present disclosure, there is provided a transparent adhesive sheet for affixing a surface protective layer or a touch panel in an image display device and a display surface of an image display unit, or a surface protective layer and a touch panel. The sheet has a storage elastic modulus of 1.0 × 10 ⁴ Pa or less, 1.0 × 10 ³ Pa or more at 1 Hz and 80 ° C., and (A) an alicyclic hydrocarbon resin, and (B) saturation. The amount of the component (B) is 10 to 200 parts by mass based on 100 parts by mass of the component (A), including polyolefin, (C) a resin having an acrylic group, and (D) an initiator that causes the reaction of the resin. The amount of the component (C) is 10 to 200 parts by mass, and the amount of the component (D) is 0.1 to 20 parts by mass.

  Moreover, according to another aspect of this indication, the image display apparatus containing an image display unit, the said transparent adhesive sheet, and a surface protective layer is provided.

  Here, the “storage modulus” means a storage modulus when a viscoelasticity measurement is performed in a temperature range of −60 ° C. to 200 ° C. at a rate of temperature increase of 5 ° C./min and a shear mode of 1 Hz. In the present invention, the surface of the pressure-sensitive adhesive sheet to which the surface protective layer or the touch panel is attached is attached at the attaching temperature (usually 40 to 80 ° C.) in the step of attaching to the display surface of the image display unit. The value at the soldering temperature is important.

  By using the manufacturing method provided as one embodiment of the present invention, the manufactured image display device 1) does not cause display unevenness on the display surface, and 2) the surface protective layer and the image even in a high temperature and high humidity environment. When affixed to the display surface of the display unit or the touch panel, bubbles are not generated at the interface between them. 3) The peeling of the adhesive sheet attached between the surface protective layer or the touch panel and the display surface of the image display unit can also be suppressed. .

  In other words, if the transparent adhesive sheet provided as another aspect of the present disclosure is used, the surface protective layer or touch panel in the image display device and the display surface of the image display unit are attached, or the surface protective layer and the touch panel are attached. When used for the display, display unevenness does not occur. In particular, when a transparent adhesive sheet is applied to the surface protective layer having an uneven shape, or the transparent adhesive sheet is applied to an image display unit display surface provided with a layer having an uneven shape (for example, a polarizing plate). Even in this case, display unevenness can be prevented.

Further, when the transparent adhesive sheet is affixed to the surface protective layer in the image display device, the display surface of the image display unit or the touch panel, bubbles do not occur at the interface even in a high temperature / high humidity environment. Furthermore, it is possible to suppress peeling after the surface protective layer or the touch panel and the display surface of the image display unit in the image display device are attached and after the surface protective layer and the touch panel are attached.
Furthermore, since the transparent adhesive sheet has low water absorption, whitening in the image display device can be prevented.

A method for manufacturing an image display device provided as one embodiment of the present disclosure includes:
(1) A pressure-sensitive adhesive sheet having a storage elastic modulus of 1.0 × 10 ⁴ Pa or less and 1.0 × 10 ³ Pa or more at 1 Hz and 80 ° C., and (A) an alicyclic hydrocarbon resin , (B) a saturated polyisobutylene resin, (C) a resin having an acrylic group, and (D) a photoinitiator that causes the reaction of the resin, and the component (B) based on 100 parts by mass of the component (A) The amount is 10 to 200 parts by mass, the amount of component (C) is 10 to 200 parts by mass, and the amount of component (D) is 0.1 to 20 parts by mass. Process,
(2) The process of sticking the said adhesive sheet on a surface protective layer or a touchscreen,
(3) A process of attaching the surface opposite to the adhesive sheet to which the surface protective layer or the touch panel is attached to the display surface of the image display unit. (4) From the surface protective layer to which the adhesive sheet is attached or from the opposite surface of the touch panel It includes a step of irradiating ultraviolet rays and curing the adhesive.

  The alicyclic hydrocarbon resin (A) as the first component is a resin excellent in low water absorption, and is compatible with an amorphous saturated polyolefin resin such as a saturated polyisobutylene resin at the same time, and a composition before curing. The storage elastic modulus of the object at room temperature can be controlled. Specific examples include petroleum resins, terpene resins, rosin resins known as tackifiers, hydrogenated resins obtained by hydrogenating them, and modified resins copolymerized with aromatics.

  Specifically, alicyclic hydrocarbon resins include terpene resins (Clearon P, M, K series, etc.), rosin and rosin ester resins (Foral AX, Foral 105, Pencel A, Ester Gum H, Super Ester A series) Etc.), disproportionated rosin and disproportionated rosin ester resins (Pine Crystal Series, etc.), obtained by copolymerization of C5 fractions such as pentene, isoprene, piperine, 1.3-pentadiene generated by thermal decomposition of petroleum naphtha Hydrogenated dicyclopentadiene resins (Escollets 5300, 5400 series, Eastotac H series, etc.), partially hydrogenated aromatic modified dicyclopentadiene resins (Escollets 5600 series, etc.), petroleum C9 fractions such as indene, vinyltoluene, α- or β-methylstyrene produced by thermal decomposition of naphtha are copolymerized It includes resins obtained by hydrogenating C9 petroleum resins (Alcon P or M series), resins obtained by hydrogenating copolymer petroleum resins of C5 fraction and C9 fraction (Imabe series), and others. Of these polymers, hydrogenated resins are preferred from the viewpoint of ensuring low water absorption and transparency.

  Examples of the hydrogenated resin include a partially hydrogenated resin having a different hydrogenation rate to a fully hydrogenated resin, and any of them can be used, but water absorption, compatibility with a binder polymer, transparency From the standpoint of ensuring, etc., a completely hydrogenated product is preferred.

  In addition, the alicyclic hydrocarbon resin has a softening point (ring-and-ball softening point), and those having an arbitrary ring-and-ball softening point can be used from the viewpoint of adhesion of the composition, operating temperature, ease of production, and the like. Usually, those having a ring-and-ball softening point in the range of about 50 to 200 ° C and in the range of about 70 to 150 ° C can be used.

  The weight average molecular weight of the alicyclic hydrocarbon resin is usually in the range of about 200 to 5,000, particularly in the range of about 500 to 3,000. This is because, within this range, the storage elastic modulus at the pasting temperature can be lowered, and compatibility with the amorphous saturated polyolefin can be secured.

  In the transparent adhesive sheet of the present invention, the alicyclic hydrocarbon resin can be blended with the amorphous saturated polyolefin in various proportions. Usually, it is preferable to blend 100 parts by mass of an alicyclic hydrocarbon resin and a lower limit of 10 parts by mass and 20 parts by mass as an upper limit of 200 parts by mass and a saturated polyolefin as 150 parts by mass.

  The amorphous saturated polyolefin (B) as the second component is a polyolefin having substantially no carbon-carbon double bond or triple bond. Of the carbon-carbon bonds contained in the saturated polyolefin, 90% or more are single bonds. Examples of saturated polyolefins include polyisobutylene, poly α-olefins, ethylene / propylene copolymers, ethylene / α-olefin copolymers, propylene / α-olefin copolymers, hydrogenated polybutadiene, and blocks of these with styrene. A copolymer etc. are mentioned. These may be used alone or in combination of two or more.

  An amorphous polymer refers to a polymer that has a very low degree of crystallinity or cannot be in a crystallized state. For amorphous polymers, the glass transition point is measured, but the melting point is not measured. When an amorphous polymer is used, there is no decrease in transparency due to crystallization.

  More specifically, the amorphous saturated polyolefin is preferably composed of a block copolymer (hereinafter referred to as a block copolymer) containing a saturated polyolefin block and an aromatic vinyl monomer block. This block copolymer includes a block composed of a polyolefin having substantially no carbon-carbon double bond or triple bond, and a block composed of an aromatic vinyl monomer. Of the carbon-carbon bonds contained in the saturated polyolefin block, 90% or more are single bonds. Examples of the aromatic vinyl monomer include styrene, p-methylstyrene, α-methylstyrene, and indene. These may be used alone or in combination of two or more. Examples of the block copolymer include a styrene-ethylene-propylene-styrene block copolymer, a styrene-ethylene-propylene block copolymer, and a styrene-ethylene-butylene-styrene block copolymer.

  Of these, saturated polyisobutylene is preferred. Here, polyisobutylene is a resin having a polyisobutylene skeleton or the like in the main chain or side chain. In the case of such a polyisobutylene resin, it can be prepared by polymerizing isobutylene alone and isobutylene and n-butene, isoprene or butadiene in the presence of a Lewis acid catalyst such as aluminum chloride or boron trifluoride. Specifically, such polyisobutylene resins are known under trade names such as Vistanex (Exxon Chemical Co.), Hycar (Goodrich), Oppanol (BASF), and JSR butyl (Nippon Butyl).

  Since such an amorphous saturated polyolefin used in the present invention is excellent in compatibility with the alicyclic hydrocarbon resin (A), a transparent film can be formed. In addition, since saturated polyolefin has a low surface energy, when used as an adhesive, it tends to wet and spread on the adherend, and voids are less likely to occur between the interface and the interface. Furthermore, since the water absorption is low, it is suitable as a base resin for the sheet material.

  The amorphous saturated polyolefin is expressed in terms of weight average molecular weight (polystyrene converted molecular weight by GPC), and is usually about 10,000 or more and 2,000,000 or less, and particularly about 100,000 or more and 1,000,000. 000 or less. Within this range, fluidity can be ensured and sufficient heat resistance can be maintained.

The curable resin (C), which is the third component, increases the fluidity of the composition before curing, improves the wettability to the adherend, and follows the uneven surface of the adherend to suppress the occurrence of liquid crystal unevenness. . Moreover, the holding power can be improved by curing. Moreover, it is possible to control the physical property after hardening to a desired physical property with these addition amount and kind.
The curable resin (C) may be either a thermosetting resin or a radiation (light) curable resin.

  Examples of curable resins (liquid monomers and / or oligomers) include those known to those skilled in the art as curable acrylic compounds. In one form, these are acrylated urethanes, acrylated epoxies, aminoplast derivatives having an α, β-unsaturated carbonyl group, ethylenically unsaturated compounds, isocyanurate derivatives having at least one acrylate group, at least It is selected from the group consisting of isocyanates having one acrylate group, and mixtures thereof.

  The curable acrylic compound generally has a (meth) acryloyl group in the molecule, and has a molecular weight of 70 to 700, and in one embodiment, 80 to 600. Usually, acrylic ester, methacrylic ester and the like are included. Specific examples of the photocurable acrylic compound include the following.

  Examples of monofunctional acrylic monomers include lauryl (meth) acrylate, cetyl (meth) acrylate (n-C16), stearyl (meth) acrylate (n-C18), aralkyl (meth) acrylate (n-C20), behenyl ( (Meth) acrylates having a linear alkyl group such as (meth) acrylate (n-C22), 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, isododecyl (meth) ) Acrylate, isotridecyl (meth) acrylate, isomyristyl (meth) acrylate, isocetyl (meth) acrylate (iso-C16), isostearyl (meth) acrylate (iso-C18), 2-octyldodecanyl (meth) acryl Having a branched alkyl group such as chromatography preparative (iso-C20) (meth) acrylate. Moreover, alicyclic (meth) acrylates, such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, are mentioned. Further, substituted acrylamides such as N, N-dimethylacrylamide, N, N-diethylacrylamide, acryloylmorpholine, N, N-dimethylaminopropylacrylamide, isopropylacrylamide, t-butylacrylamide, and t-octylacrylamide can also be exemplified.

  Examples of polyfunctional acrylic monomers include hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, nonanediol di (meth) acrylate, decandiol di (meth) acrylate, dodecanediol di (meth) acrylate, Cyclohexanedimethanol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, hydrogenated bisphenol A di (meth) acrylate, hydrogenated polybutadiene di (meth) acrylate, hydrogenated isoprene (meth) acrylate, trimethylolpropane And tri (meth) acrylate. Moreover, the acrylate which oligomerized the polyhydric alcohol used for these acrylic monomers by the urethane bond is also used. Furthermore, mixtures thereof can also be used.

  Usually, among the above use modes, a (meth) acrylate resin having a long chain having 9 or more carbon atoms or an alicyclic skeleton is preferable. In general, a photocurable resin having a (meth) acryloyl group or a glycidyl group has a relatively high polarity and is hardly compatible with a saturated polyolefin having a very low polarity. However, these compounds are alicyclic hydrocarbon resins (A). And a mixture of the saturated polyolefin (B).

In the pressure-sensitive adhesive sheet of the present invention, the (C) curable resin can be blended with the (A) alicyclic hydrocarbon resin (B) non-crystalline saturated polyolefin in various proportions. Usually, the amount of the component (C) is 10 to 200 parts by weight, more preferably 50 to 150 parts by weight with respect to 100 parts by weight of the component (A) and 10 to 200 parts by weight of the component (B). It is.
By using within these ranges, a sufficient cohesive force can be obtained, and the composition can be hardly peeled off with little shrinkage during curing.

  Specific examples of radiation (photo) polymerization initiators include benzophenone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, camphorquinone, benzoin as radical polymerization initiators. , Benzoin methyl ether, benzoin-n-propyl ether, benzoin-n-butyl ether, benzyl, p-methylbenzophenone, diacetyl, eosin, thionine, Michler's ketone, acetophenone, 2-chlorothioxanthone, anthraquinone, chloroanthraquinone, 2-methyl Anthraquinone, (α-hydroxyisobutylphenone, p-isopropyl-α-hydroxyisobutylphenone, α, α'-dichloro-4-phenoxyacetophenone, 1-hydroxy-1-cyclohexylacetophenone, 2,2-di Toxi-2-phenylacetophenone, methylbenzoinformate, dichlorothioxanthone, diisopropylthioxanthone, phenyl disulfide-2-nitrosofluorene, butyroin, anisoin ethyl ether, tetramethylthiuram disulfide, 2,2-dimethoxy-1,2-diphenyl Ethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2 -Hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane- 1-one, 2-methyl-1- (4-methyl (Luthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4- Methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl)- Examples thereof include phenylphosphine oxide.

  Specific examples of the thermal polymerization initiator include radical polymerization initiators such as isobutyryl peroxide, cumyl peroxyneodecanoate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, cumyl peroxyneohexa Nonate, di (2-ethoxyethyl) peroxydicarbonate, di (methoxyisopropyl) peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, t-butylperoxyneodecanoate, t-hexylper Examples thereof include organic peroxides such as oxyneohexaate, t-butyryl peroxyneohexanoate, t-butyl peroxypivalate, lauroyl peroxide, cumyl peroxyoctate, and benzoyl peroxide. Also, 2,2′-azobis (4-methoxy-2,4, dimethylvaleronitrile) 2,2′-azobis (2-cyclopropylpropionitrile) 2,2′-azobis (2,4-methylvaleronitrile) ) 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2-methylpropionate), 4,4'-azobis ( Azo compounds such as 4-cyanovaleric acid).

  (D) Radiation (light) or a thermal polymerization initiator is contained in an amount of 0.1 to 20 parts by mass, and in one form, 0.5 to 5 parts by mass. This is because, within these ranges, the acrylic monomer can be favorably polymerized and the storage stability of the resin composition can be secured.

  By using the above-described monomer component in the above-described composition, the obtained pressure-sensitive adhesive sheet can achieve sufficient followability at the time of application before curing, and has sufficient holding power after curing. By using such a transparent pressure-sensitive adhesive sheet having sufficient followability, an image display unit display surface provided with a surface protective layer having an uneven shape, or a layer having an uneven shape (for example, a polarizing plate) Even when the transparent adhesive sheet is applied, irregularities can be absorbed, and as a result, display unevenness in the image display device can be prevented. In addition, even when there is variation in the thickness of the sheet itself, it has sufficient flexibility so that it can be bonded to the surface of the adherend without any gap, and display unevenness in the image display device can be prevented. .

Here, the followability of the pressure-sensitive adhesive sheet can be represented by the storage elastic modulus of the resin composition. If the storage elastic modulus at 80 ° C. and 1 Hz of the resin composition is 1 × 10 ⁴ Pa or less, even when an adhesive sheet is bonded to an adherend having an uneven surface of about 10 μm, display unevenness is suppressed. Can do. Furthermore, when the storage elastic modulus at 80 ° C. and 1 Hz of the resin composition is 1 × 10 ⁴ Pa or less, even when the pressure-sensitive adhesive sheet is bonded to an adherend having a large uneven surface or a complicated uneven surface. Therefore, display unevenness can be reduced. Moreover, if it is 1.0 * 10 < ³ > Pa or more, a resin composition will not leak at the time of affixing, and the inconvenience in use will not arise. The storage elastic modulus of the resin composition can be adjusted by appropriately changing the types, molecular weights, and composition ratios of the A, B, and C components.

  Furthermore, whitening in the image display device can be prevented by giving the adhesive sheet low water absorption. The degree of whitening prevention (transparency) can be expressed by a haze value. Here, the measurement of a haze value is performed by the following environmental tests based on JIS K7136. First, a transparent adhesive sheet is bonded to a transparent adherend (for example, a surface protective layer of an image display device) to form a laminate, and the obtained laminate is in an environment of a temperature of 60 ° C. and a relative humidity (RH) of 90%. For 3 days, and the haze value of the laminate after standing for 3 days is measured. When the haze value of the laminate obtained by bonding the surface protective layer and the transparent adhesive sheet of the image display device is 2% or less, it can be determined that whitening has not occurred.

  Further, the pressure-sensitive adhesive sheet has a total light transmittance (JIS K) in the visible light wavelength region of the laminate obtained when the laminate is laminated on a transparent adherend (for example, a surface protective layer of an image display device). 7361) has a transparency of 90% or more.

  In addition to the above composition, the pressure-sensitive adhesive sheet may contain other components such as a filler, an antioxidant, and a silane coupling agent.

  The thickness of the pressure-sensitive adhesive sheet is a thickness that does not cause a problem in attachment to the image display device (attachment between the surface protective layer or touch panel and the display surface of the image display unit in the image display device, or attachment between the surface protective layer and the touch panel). If so, there is no particular limitation. For example, the thickness can be 0.025 to 1 mm. When the thickness of the transparent adhesive sheet is increased, the adhesive force to an adherend (polymer film such as PMMA or glass plate) is increased.

  Next, an image display device including the above-described adhesive sheet will be described with reference to FIGS. Here, the image display device includes an image display unit, a transparent adhesive sheet, and a surface protective layer. In the transparent adhesive sheet included in the image display device, the internal residual stress in the transparent adhesive sheet is relaxed.

  The image display unit is not particularly limited, and includes a reflective or backlight type liquid crystal display unit, a plasma display unit, an electroluminescence (EL) display, an image display unit such as electronic paper, and the like. An additional layer (which may be a single layer or multiple layers), for example, a polarizing plate (which may have an uneven surface) may be provided on the display surface of the image display unit. Further, a touch panel as described later may be present on the display surface of the image display unit.

  The surface protective layer is a layer disposed on the outermost surface when disposed on the image display device. The surface protective layer may be composed of only a polymer film, a glass plate or the like, or may be composed of a plurality of layers together with other layers. The surface protective layer is not particularly limited as long as it is conventionally used as a protective film for an image display device, for example, an acrylic resin film such as polymethyl methacrylate (PMMA), a polycarbonate resin film, or a glass plate. Can be. Although the thickness of a film or a glass plate is not limited, Usually, it is 0.1-5 mm.

  When the surface protective layer is a laminate composed of multiple layers, the observer side of the image display device has functions such as wear resistance, scratch resistance, antifouling properties, antireflection properties, and antistatic properties. A layer for imparting characteristics can be provided. The layer for imparting abrasion resistance and scratch resistance can be formed by applying and curing a curable resin composition capable of forming a hard coat. For example, a paint composed of colloidal silica and a partial condensation reaction product of a silane mixture containing alkyltrialkoxysilane as a main component is applied and then cured by heating to form a cured film, or a polyfunctional acrylate as a main component. A cured coating film can be formed by applying the coating material described above and irradiating the coating film with ultraviolet rays. In order to ensure antifouling properties, a resin layer containing an organosilicon compound or a fluorine-based compound can be formed. Furthermore, in order to obtain antistatic properties, a resin layer containing a surfactant and conductive fine particles can be formed. The layer for imparting such functions / characteristics is desirably a layer that does not hinder the transparency of the surface protective layer, and is preferably as thin as possible within a range where the function can be exhibited. Although the layer which provides a functional characteristic is not limited, Usually, it is 0.05-10 micrometers.

  When the surface protective layer is a laminate composed of a plurality of layers, an additional layer such as a printed layer, a hard coat layer, or a vapor deposition layer is formed on the entire surface of the surface protective layer or a partial region on the transparent adhesive sheet side. May be included. When such an additional layer is formed in a partial region of the surface protective layer, the surface protective layer becomes a surface having an uneven shape. The thickness of the surface protective layer is usually 0.1 to 6 mm as a whole, including such additional layers. In addition, when an additional layer is a printing layer or vapor deposition layer used as a light shielding layer as described later, the thickness of the layer is usually 10 μm or less. In other embodiments, the layer thickness is generally 100 μm or less, or 50 μm or less.

  FIG. 1 shows a cross-sectional view of one embodiment of an image display device including the transparent adhesive sheet described above. The image display device 10 has a structure in which the transparent adhesive sheet 3 and the surface protective layer 4 are laminated in this order on the display surface of the image display unit 1. The surface protective layer 4 is composed of a continuous layer 5 and a light shielding layer 6 provided in a partial region on the lower surface of the continuous layer 5 (on the transparent adhesive sheet 3 side), and the surface has an uneven shape. In addition, the light shielding layer 6 is applied to a predetermined region of the continuous layer 5 by applying a liquid in which a coloring agent is mixed into the coating solution of the curable resin composition, by an appropriate method such as screen printing, and the like. It is formed by curing with a proper curing method. The transparent adhesive sheet 3 is affixed to the concavo-convex shape side of the surface protective layer 4. Since the transparent adhesive sheet 3 has flexibility, even if the surface protective layer 4 has an uneven shape, a layer (for example, a polarizing plate) having an uneven surface shape is further provided on the display surface of the image display unit. Even in such a case, the internal residual stress of the sheet itself is alleviated, and display unevenness in the image display apparatus can be prevented. Moreover, since the transparent adhesive sheet 3 has sufficient adhesive force and hydrophilicity, even in a high temperature and high humidity environment, the interface between the display surface of the image display unit 1 and the transparent adhesive sheet 3, and the transparent adhesive sheet 3 Bubbles and peeling do not occur at the interface with the surface protective layer 4, and whitening does not occur. Here, the image display device 10 is obtained by bonding the laminate 2 composed of the surface protective layer 4 and the transparent adhesive sheet 3 to the display surface of the image display unit 1.

  FIG. 2 is a cross-sectional view of another aspect of the image display device including the transparent adhesive sheet. In FIG. 2, the image display device 20 has a structure in which the transparent adhesive sheet 3 and the surface protective layer 4 are laminated in this order on the touch panel 7 existing on the display surface of the image display unit 1. The structure of the laminate 2 in which the transparent adhesive sheet 3 and the surface protective layer 4 are laminated in this order is the same as that shown in FIG. The touch panel 7 is disposed on the display surface of the image display unit 1, and the image display on the image display device 20 can be seen through the touch panel. The touch panel 7 is transparent. For example, a transparent conductive layer is disposed on the back surface of two transparent plates made of glass or polyethylene terephthalate (PET), and the transparent conductive layers of the transparent plates are arranged with a small gap therebetween. And have a configuration in which they face each other in a non-contact state. When the touch panel operator presses the corresponding position on the surface of one transparent plate with a finger or a pen, the transparent conductive layer on the back of one transparent plate comes into contact with the transparent conductive layer on the other transparent plate and is conductive only at the corresponding position. It becomes possible. The position on the touch panel pressed by the operator can be specified by the sensor that electrically senses the position at which this conduction is possible. Such touch panel type displays are used in portable terminals such as PCs (personal computers), mobile phones, and PDAs. Since the transparent adhesive sheet 3 has flexibility, even if the surface protective layer 4 has an uneven shape, the internal residual stress of the sheet itself is relaxed, and display unevenness in the image display device can be prevented. Moreover, since the transparent adhesive sheet 3 has sufficient adhesive force and hydrophilicity, even in a high temperature and high humidity environment, the interface between the touch panel 7 and the transparent adhesive sheet 3, and the transparent adhesive sheet 3 and the surface protective layer 4 No bubbles or peeling occurs at the interface, and whitening does not occur. Here, the image display device 20 is obtained by bonding the laminate 2 composed of the surface protective layer 4 and the transparent adhesive sheet 3 to the touch panel 7 existing on the display surface of the image display unit 1.

  FIG. 3 is a cross-sectional view of still another aspect of the image display device including the transparent adhesive sheet. In FIG. 3, the image display device 30 has a structure in which a transparent adhesive sheet 3, a touch panel 7, a transparent adhesive sheet 3 ′, and a surface protective layer 4 are laminated in this order on the display surface of the image display unit 1. Yes. The structure of the laminate in which the transparent adhesive sheet 3 ′ and the surface protective layer 4 are laminated in this order is the same as that described in FIG. 1. The transparent pressure-sensitive adhesive sheet 3 and the transparent pressure-sensitive adhesive sheet 3 ′ may contain the same copolymer or different copolymers. Since the transparent adhesive sheets 3 and 3 ′ have flexibility, even if the surface protective layer 4 has an uneven shape, a layer having an uneven surface shape on the display surface of the image display unit (for example, a polarizing plate). Even if this is provided, the internal residual stress of the sheet itself is relaxed, and display unevenness in the image display apparatus can be prevented. Moreover, since the transparent adhesive sheets 3 and 3 ′ have sufficient adhesive force and hydrophilicity, the display surface of the image display unit 1, the transparent adhesive sheet 3, and the transparent adhesive sheet 3 ′ even under a high temperature and high humidity environment. In addition, bubbles and peeling do not occur at each interface of the surface protective layer 4 and the like, and whitening does not occur. Here, the image display device 30 bonds the laminate 2 composed of the surface protective layer 4, the transparent adhesive sheet 3 ′, the touch panel 7, and the transparent adhesive sheet 3 on the display surface of the image display unit 1. can get.

  FIG. 4 is a cross-sectional view of still another aspect of the image display device including the transparent adhesive sheet. In FIG. 4, the image display device 40 has a structure in which a transparent adhesive sheet 3, a touch panel 7, and a surface protective layer 4 are laminated in this order on the image display unit 1. As in FIG. 1, the surface protective layer 4 has a light shielding layer 6 in a partial region, and the surface has an uneven shape. The transparent adhesive sheet 3 is present on the concave and convex surface side of the surface protective layer 4 via the touch panel 7. Since the transparent adhesive sheet 3 has flexibility, even if a layer having an uneven surface shape (for example, a polarizing plate) is provided on the display surface of the image display unit, the internal residual stress of the sheet itself is relaxed, Display unevenness in the image display device can be prevented. Moreover, since the transparent adhesive sheet 3 has sufficient adhesive force and hydrophilicity, even in a high temperature and high humidity environment, the interface between the display surface of the image display unit 1 and the transparent adhesive sheet 3, and the transparent adhesive sheet 3 Bubbles and peeling do not occur at the interface with the touch panel 7, and whitening does not occur. Here, the image display device 40 is obtained by bonding the laminate 2 composed of the surface protective layer 4, the touch panel 7 and the transparent adhesive sheet 3 to the display surface of the image display unit 1.

  According to still another aspect of the present disclosure, an electronic device including the image display device is provided. The electronic device is not particularly limited, and includes a mobile phone, a personal digital assistant (PDA), a portable game machine, an electronic reading terminal, a car navigation system, a portable music player, a clock, a television (TV), a video camera, a video player, Examples include digital cameras, global positioning system (GPS) devices, and personal computers (PCs).

  Hereinafter, although it demonstrates still in detail using an Example, it is not limited to these Examples.

1. Sample preparation method [Example 1]
100 parts by mass of a hydrogenated DCPD resin (Escorez5340 manufactured by ExxonMobil) as an alicyclic hydrocarbon resin, 17 parts by mass of a saturated polyisobutylene resin (OPanol B100 manufactured by BASF) as an amorphous saturated polyolefin resin, and an acrylic group 50 parts by mass of UV curable acrylate resin (DCP manufactured by Shin-Nakamura Chemical Co., Ltd.) as a resin having, 0.8 parts by mass of photoinitiator (TPO manufactured by Ciba Specialty Chemicals Co., Ltd.) as an initiator, dissolved in toluene, A 25% by weight solution was made. This solution was coated on a peeled PET film having a thickness of 38 μm and dried in an oven at 100 ° C. for 30 minutes. The obtained film with pressure-sensitive adhesive was laminated with a 25 μm-thick peeled PET film to prepare a pressure-sensitive adhesive sheet with a release liner. A transparent film having a pressure-sensitive adhesive thickness of 25 μm was obtained.
[Example 2]
100 parts by mass of hydrogenated DCPD resin (Excore Mobil Escorez5340) as alicyclic hydrocarbon resin, 25 parts by mass of saturated polyisobutylene resin (OSFanol B50 from BASF) as non-crystalline saturated polyolefin resin Type of saturated polyisobutylene resin (BASF Opanol B15) 8 parts by weight, acrylic resin having UV curable acrylate resin (Shin Nakamura Chemical Co., Ltd. DCP) 33 parts by weight, initiator photoinitiator Same as Example 1 except that 0.8 parts by mass of TPO (Ciba Specialty Chemicals Co., Ltd. TPO) was used.
Example 3
100 parts by mass of hydrogenated DCPD resin (Excore Mobil Escorez 5340) as alicyclic hydrocarbon resin, 40 parts by mass of hydrogenated polybutadiene resin (Kuraray LIR200) as non-crystalline saturated polyolefin resin and polyalphaolefin copolymer (X1102P manufactured by Sumitomo Chemical Co., Ltd.) 20 parts by mass, 40 parts by mass of polybutadiene urethane modified with hydrogenated diacrylate as a resin having an acrylic group (TEAI1000 manufactured by Nippon Soda Co., Ltd.), photoinitiator (Ciba Specialty) Same as Example 1 except that TPO) made by Chemicals Co., Ltd. was 1 part by mass.
Example 4
100 parts by mass of hydrogenated DCPD resin (Escorez5340 manufactured by ExxonMobil) as an alicyclic hydrocarbon resin, 40 parts by mass of saturated polyisobutylene resin (OPanol B50 from BASF) as an amorphous saturated polyolefin resin, and acrylic group Except for having 60 parts by mass of tricyclodecane dimethanol diacrylate (SPBDA-S30 made by Osaka Organic Chemical Co., Ltd.) as the resin, and 1.3 parts by mass of photoinitiator (TPO made by Ciba Specialty Chemicals Co., Ltd.) as the initiator, Same as Example 1.
Example 5
100 parts by mass of hydrogenated DCPD resin (Escorez5340, manufactured by ExxonMobil) as an alicyclic hydrocarbon resin, 100 parts by mass of saturated polyisobutylene resin (Opanol B30, manufactured by BASF) as an amorphous saturated polyolefin resin, and acrylic group Except that 50 parts by mass of tricyclodecane dimethanol diacrylate (A-DCP manufactured by Shin-Nakamura Co., Ltd.) is used as the resin, and 1 part by mass of photoinitiator (TPO manufactured by Ciba Specialty Chemicals Co., Ltd.) is used as the initiator. Same as Example 1.

[Comparative Example 1]
87.5 parts by mass of isooctyl acrylate, 4 parts by mass of acrylic acid and 0.04 parts by mass of Irgacure 651 (2,2-dimethoxy-2-phenylacetophenone) as a photopolymerization initiator are mixed well in a glass container and dissolved in nitrogen gas. Then, ultraviolet rays were irradiated for several minutes with a low-pressure mercury lamp and partially polymerized to obtain a viscous liquid having a viscosity of about 1500 cP. Add 8.5 parts by mass of 2-hydroxyethyl acrylate, 0.1 parts by mass of HDDA (1,6-hexanediol diacrylate) as a crosslinking agent, and 0.1 parts by mass of an additional polymerization initiator (Irgacure 651) to the obtained composition, Was stirred. This mixture was vacuum degassed and then coated on a 50 μm thick polyester film that had been peeled off, and then covered with the above film to remove oxygen that would inhibit polymerization. Irradiation with a lamp for about 4 minutes gave an adhesive sheet.
[Comparative Example 2]
The same as Comparative Example 1 except that 87.5 parts by mass of isooctyl acrylate and 12.5 parts by mass of acrylic acid were added, and 2-hydroxyethyl acrylate was not added.
[Comparative Example 3]
Hydrogenated DCPD resin (Excore Mobil Escorez 5340) 100 parts by mass, polyisobutylene resin (BASF Opanol B100) 33.4 parts by mass, UV curable acrylate resin (Shin Nakamura Chemical Co., Ltd. DCP) 33.4 parts by mass Except for this, the same as Example 1.

2. Evaluation method (1) Unevenness test The release film of the pressure-sensitive adhesive sheet to be evaluated is peeled off on one side and attached to a 0.7 mm thick glass plate (Corning # 1737) so that air does not enter with a roller, and the protruding part is removed with a cutter. . On the other hand, remove the entire protective cover of the commercially available mobile phone (Sharp 913SH) and put the liquid crystal module on the surface. The release film of the adhesive sheet affixed to the glass plate was peeled off, and the adhesive surface was pressure-bonded with a rubber roller with the liquid crystal module side. The obtained glass plate / adhesive sheet / liquid crystal module laminate was placed in an autoclave and treated at 40 ° C. and 0.5 MPa for 15 minutes. [Example 1] [Example 2] [Example 3] [Example 4] [Example 5] [Comparative Example 3] From the glass plate side, ultraviolet rays (F300S manufactured by Fusion Co., Ltd. (H valve use), 50 mJ × 20 times). After that, the cellular phone was turned on to display a white screen, and the unevenness was visually confirmed. The results are shown in Table 1. In the unevenness test results shown in Table 1, “◯” means “no unevenness is observed”, and “x” means “strong unevenness is observed and there is a problem in practical use”.

(2) Reliability test (foaming, peeling, whitening)
The release film of the pressure-sensitive adhesive sheet to be evaluated was peeled off on one side and attached to a 0.7 mm thick glass plate (Corning # 1737) so that air did not enter with a roller, and the protruding part was removed with a cutter. On the other hand, a polarizing plate with an adhesive (manufactured by Sanritz) was similarly attached to a 0.55 mm thick float glass (50 × 80 mm) with a rubber roller. The release film of the pressure-sensitive adhesive sheet attached to the acrylic plate was peeled off and pressure-bonded using a rubber roller so that the pressure-sensitive adhesive surface was adhered to the polarizing plate. The obtained glass plate / adhesive sheet / polarizing plate / glass laminate was placed in an autoclave and treated at 40 ° C. and 0.5 MPa for 15 minutes. [Example 1] [Example 2] [Example 3] [Example 4] [Example 5] [Comparative Example 3] From the glass plate side, ultraviolet rays (F300S manufactured by Fusion Co., Ltd. (H valve use), 50 mJ × 20 times). After leaving at room temperature for 12 hours, it was placed in a constant temperature and humidity chamber at 60 ° C. and 90% RH. The appearance of the laminate taken out after 3 days was visually confirmed. The results are shown in Table 1.

(3) Viscoelasticity measurement Viscoelasticity evaluation was performed in a shear mode (1 Hz) using a dynamic viscoelasticity measuring device ARES manufactured by TI Instruments. A laminate of 16 transparent adhesive sheets from which the release film had been removed was punched out with a 7.9 mmφ punching blade to obtain a test piece. Measurements were made at −60 to 200 ° C. at a rate of temperature increase of 5 ° C./min. Table 1 shows the storage elastic modulus values at 25 ° C. and 80 ° C.

3. Evaluation results

Sectional drawing of 1 aspect of the image display apparatus containing the laminated body of this indication is shown. Sectional drawing of another aspect of the image display apparatus containing the laminated body of this indication is shown. Sectional drawing of another aspect of the image display apparatus containing the laminated body of this indication is shown. Sectional drawing of another aspect of the image display apparatus containing the laminated body of this indication is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20, 30, 40 Image display apparatus 1 Image display unit 2 Laminated body 3 Transparent adhesive sheet 4 Surface protective layer 5 Continuous layer 6 Light shielding layer 7 Touch panel

Claims (9)

(1) A pressure-sensitive adhesive sheet having a storage elastic modulus of 1.0 × 10 ⁴ Pa or less and 1.0 × 10 ³ Pa or more at 1 Hz and 80 ° C., and (A) an alicyclic hydrocarbon resin (B) a non-crystalline saturated polyolefin resin, (C) an acrylic group-containing resin, and (D) an initiator that causes the reaction of the resin, and (B) component based on 100 parts by mass of component (A) The amount of is 10 to 200 parts by weight, the amount of component (C) is 10 to 200 parts by weight, and the amount of component (D) is 0.1 to 20 parts by weight. The process of
(2) The process of sticking the said adhesive sheet on a surface protective layer or a touchscreen,
(3) A step of affixing the surface opposite to the pressure-sensitive adhesive sheet to which the surface protective layer or the touch panel is attached to the display surface of the image display unit. (4) A step of curing the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet. Manufacturing method.   The method for producing an image display device according to claim 1, wherein in the step of curing the pressure-sensitive adhesive, the pressure-sensitive adhesive is cured by irradiating ultraviolet rays from the surface protective layer to which the pressure-sensitive adhesive sheet is attached or the opposite surface of the touch panel. A transparent pressure-sensitive adhesive sheet for affixing a surface protective layer or a touch panel and a display surface of an image display unit in an image display device, or a surface protective layer and a touch panel, wherein the transparent pressure-sensitive adhesive sheet has a storage elastic modulus of 1 Hz, At 80 ° C., 1.0 × 10 ⁴ Pa or less, 1.0 × 10 ³ Pa or more, and (A) an alicyclic hydrocarbon resin, (B) an amorphous saturated polyolefin, (C) an acrylic group And (D) an initiator that causes the reaction of the resin, and the amount of the component (B) is 10 to 200 parts by mass based on 100 parts by mass of the component (A), and the component (C) The amount of is a transparent adhesive sheet whose amount of (D) component is 0.1-20 mass parts.   The transparent adhesive sheet according to claim 3, wherein the alicyclic hydrocarbon resin is a cyclic olefin-based resin.   The transparent adhesive sheet according to claim 3 or 4, wherein the alicyclic hydrocarbon resin is hydrogenated.   The transparent adhesive sheet according to claim 3, wherein the amorphous saturated polyolefin is a saturated polyisobutylene resin.   The transparent pressure-sensitive adhesive sheet according to any one of claims 3 to 6, wherein the transparent pressure-sensitive adhesive sheet is attached to the concavo-convex surface side of the surface protective layer having one surface having a concavo-convex shape.   The image display apparatus containing an image display unit, the transparent adhesive sheet of any one of Claims 3-7, and a surface protective layer.   The image display device according to claim 8, wherein an internal residual stress in the transparent adhesive sheet is relaxed.

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