JP2012107130A - Adhesive sheet and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet that is one arranged between a display panel and a transparent protective plate and does not cause bubbles after close adhesion between the transparent protective plate and the display panel.SOLUTION: The adhesive sheet is arranged between a display panel of a display device and a transparent protective plate provided with a decorative layer at the display panel side. The adhesive is a urethane-based adhesive and the adhesive sheet has initial adhesive force to a soda glass plate of ≥10 N/25 mm.

Description

  The present invention relates to a pressure-sensitive adhesive sheet used for closely attaching each member (display panel, transparent protective plate, touch panel) of a display device such as a liquid crystal display and an organic EL display, and a display device using the pressure-sensitive adhesive sheet.

  In display devices used in electronic devices such as mobile phones, car navigation systems, personal computers, ticket machines, bank terminals, liquid crystal display panels, organic EL display panels and other display panels are provided with a certain gap (air layer), A structure in which a touch panel and a transparent protective plate are arranged is adopted.

  However, when a structure having a gap as described above (for example, a structure having a gap between the display panel and the transparent protective plate or between the touch panel and the transparent protective plate) is used, light scattering is caused by the presence of the gap. This causes problems such as a decrease in contrast and brightness. In addition, a gap of a certain size or more is required to protect the display panel, which hinders thinning.

  In order to solve such a problem, it has been proposed to fill a space between the display panel and the transparent protective plate with a photo-curing resin or a thermosetting resin and to cure (for example, Patent Documents 1 to 4). Moreover, the system which adhere | attaches a display panel and a transparent protective board with an adhesive sheet with respect to the system filled and hardened | cured said resin is known (for example, patent documents 5-8).

Japanese Patent Laid-Open No. 11-174417 JP 2005-55641 A JP 2007-297582 A JP 2008-281997 A Japanese Patent Laid-Open No. 2004-212521 JP 2008-266473 A JP 2009-98324 A JP 2009-155503 A

  The resin filling and curing method described above is performed by filling a resin between a display panel and a transparent protective plate with a photocurable resin or a thermosetting resin, and then curing the resin with light (such as ultraviolet rays) or heat. There is a problem that the display panel is deformed due to curing shrinkage when cured, or there is a problem that when a solvent-free curable resin composition is used, bubbles are likely to be mixed during filling because the resin composition has a high viscosity. .

  On the other hand, the above-described method of closely adhering with the pressure-sensitive adhesive sheet can avoid the deformation of the display panel as compared with the resin filling and curing method, but has not yet sufficiently satisfied the prevention of air bubble mixing. In particular, when a decorative layer (black printing layer) for bordering the boundary between the image display portion and the outer periphery is provided on the display panel side of the transparent protective plate, bubbles are likely to be generated in the step portion of the decorative layer. There was a problem.

  Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet disposed between a display panel and a transparent protective plate in view of the above-described problems of the prior art, and a pressure-sensitive adhesive that does not generate bubbles after the transparent protective plate and the display panel are in close contact with each other. To provide a sheet. Another object of the present invention is to provide a display device using the pressure-sensitive adhesive sheet of the present invention.

The above object of the present invention has been basically achieved by the following invention.
1) An adhesive sheet disposed between a display panel of a display device and a transparent protective plate provided with a decorative layer on the display panel side, wherein the adhesive is a urethane-based adhesive, and An adhesive sheet having an initial adhesion to a soda glass plate of 10 N / 25 mm or more.
2) The pressure-sensitive adhesive sheet according to 1), wherein the urethane-based pressure-sensitive adhesive is an active energy ray-curable urethane-based pressure-sensitive adhesive.
3) The pressure-sensitive adhesive sheet according to 1) or 2), wherein the thickness is 50 to 1000 μm.
4) A display device having a display panel and a transparent protective plate provided with a decorative layer on the display panel side, wherein the display panel and the display panel are interposed via the adhesive sheet of any one of 1) to 3). A display device in which a surface provided with a decorative layer of a transparent protective plate is closely attached.
5) A display device in which a display panel, a touch panel, and a transparent protective plate provided with a decorative layer on the display panel side are arranged in this order, and the adhesive sheet according to any one of 1) to 3) above A display device in which the touch panel and the surface on which the decorative layer of the transparent protective plate is provided are in close contact.

  By using the pressure-sensitive adhesive sheet of the present invention for the adhesion between the display panel or the touch panel and the transparent protective plate having the decoration layer, it is possible to prevent the generation of bubbles due to the step difference of the decoration layer.

The schematic cross section which shows an example of the display apparatus which adhered the display panel and the transparent protective plate with the adhesive sheet of this invention. The schematic cross section which shows an example of the display apparatus which contacted the touch panel and the transparent protective plate with the adhesive sheet of this invention.

  The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet disposed between a display panel of a display device and a transparent protective plate, and the transparent protective plate is provided with a decorative layer on the display panel side.

  Here, the pressure-sensitive adhesive sheet of the present invention is disposed between the display panel and the transparent protective plate, and a) an embodiment in which the pressure-sensitive adhesive sheet of the present invention is used to adhere the display panel and the transparent protective plate, (B) A mode in which the pressure-sensitive adhesive sheet of the present invention is used for closely attaching the touch panel and the transparent protective plate when the touch panel is disposed between the display panel and the transparent protective plate.

  And as a display apparatus in which the adhesive sheet of this invention is used, the display apparatus which has a display panel and a transparent protective board, and the display apparatus which has a touch panel between a display panel and a transparent protective board are mentioned.

  Examples of the display panel include a liquid crystal display panel and an organic EL display panel. Examples of the touch panel include a capacitive touch panel formed of a transparent conductive member in which a transparent conductive film such as an ITO film is laminated. Examples of the transparent protective plate include a glass plate and a plastic resin plate (for example, an acrylic resin plate, a polycarbonate resin plate, a polyester resin plate, etc.). The thickness of the transparent protective plate is generally about 0.3 to 3 mm, and more specifically in the range of 0.5 to 2 mm.

  FIG. 1 is a schematic cross-sectional view showing an example of a display device in which a display panel and a transparent protective plate are brought into close contact with the pressure-sensitive adhesive sheet of the present invention, and shows the above-mentioned aspect (a). The display panel 3 and the transparent protective plate 1 are in close contact via the pressure-sensitive adhesive sheet 2 of the present invention. A decorative layer (black print layer) 4 for fringing the image display area is provided on the outer peripheral edge of the surface of the transparent protective plate 1 on the display panel 3 side.

  FIG. 2 is a schematic cross-sectional view of an example of a display device in which the display panel 3, the touch panel 5, and the transparent protective plate 1 are arranged in this order. The touch panel 5 and the transparent protective plate 1 are separated by the adhesive sheet 2 of the present invention. This is a close-contact mode and shows the above-mentioned mode b). A decorative layer (for example, a black print layer) 4 for bordering the image display area is provided on the outer peripheral edge of the surface of the transparent protective plate 1 on the display panel 3 side.

  The decorative layer provided on the transparent protective plate is, for example, a colored layer for bordering a region corresponding to the image display region of the display panel, and is provided on the outer periphery of the transparent protective plate by printing or the like. The decorative layer preferably does not transmit light, and therefore the color of the decorative layer is preferably black, and the thickness is preferably relatively large.

  From the above viewpoint, the thickness of the decorative layer is preferably 5 μm or more, more preferably 10 μm or more, and particularly preferably 15 μm or more. The upper limit is about 40 μm.

  When the thickness of the decorative layer is relatively large as described above, the level difference between the transparent protective plate and the edge of the decorative layer becomes large, and when the transparent protective plate and the display panel or touch panel are in close contact via the adhesive sheet There is a problem that bubbles are generated in the stepped portion.

  It has been found that the above problem can be improved by setting the initial adhesive strength of the pressure-sensitive adhesive sheet to 10 N / 25 mm or more. Here, the initial adhesion is an adhesion after 5 minutes after the pressure-sensitive adhesive sheet is bonded to the soda glass plate.

  In general, the adhesive strength of the pressure-sensitive adhesive sheet increases with the elapse of time after bonding, but it has been found that the initial adhesive strength is important for solving the problems of the present invention described above.

  The initial adhesive strength of the pressure-sensitive adhesive sheet of the present invention is preferably 11 N / 25 mm or more, more preferably 12 N / 25 mm or more, and particularly preferably 13 N / 25 mm or more. The upper limit is about 50 N / 25 mm.

  The pressure-sensitive adhesive sheet of the present invention comprises a urethane-based pressure-sensitive adhesive. As will be described later, the urethane-based pressure-sensitive adhesive is suitable for producing a pressure-sensitive adhesive sheet having a large thickness, and is excellent in cutting processability.

  The pressure-sensitive adhesive sheet of the present invention has a large initial adhesion and a large thickness, so that a phenomenon that the cut end is raised at the time of cutting processing is likely to occur, but this phenomenon can be suppressed by using a urethane-based pressure-sensitive adhesive. it can.

  Moreover, when the adhesive sheet of this invention is used for adhesion | attachment with the transparent protective plate of a display apparatus, and a touchscreen, there exists an advantage that deterioration of the transparent conductive film of a touchscreen is suppressed. Conventionally known acrylic pressure-sensitive adhesives generally contain an acid, which may promote deterioration of the transparent conductive film.

  The pressure-sensitive adhesive sheet of the present invention is obtained by forming a pressure-sensitive adhesive into a sheet shape. For example, a pressure-sensitive adhesive sheet can be obtained by coating a pressure-sensitive adhesive on a release sheet (release film). In this case, the release sheet is used for protecting the pressure-sensitive adhesive sheet of the present invention during handling and distribution, and is removed when the pressure-sensitive adhesive sheet of the present invention is applied to a display device.

  The thickness of the pressure-sensitive adhesive sheet of the present invention is preferably 50 μm or more, more preferably 100 μm or more, further preferably 120 μm or more, and particularly preferably 150 μm or more. The upper limit of the thickness is about 1000 μm.

  By increasing the thickness of the pressure-sensitive adhesive sheet as described above, it is possible to sufficiently fill the step between the transparent protective plate and the decorative layer end described above, and between the transparent protective plate of the display device and the display panel. The gap or the gap between the transparent protective plate and the touch panel can be filled without a gap.

  The pressure-sensitive adhesive sheet of the present invention comprises a urethane-based pressure-sensitive adhesive. Examples of such urethane-based pressure-sensitive adhesives include solvent-based pressure-sensitive adhesives, thermosetting pressure-sensitive adhesives, and active energy ray-curable pressure-sensitive adhesives, and active energy ray-curable pressure-sensitive adhesives are preferably used.

  The active energy ray-curable pressure-sensitive adhesive can uniformly produce a pressure-sensitive adhesive sheet having a relatively large thickness as described above. As will be described later, productivity is further improved by using a solvent-free type.

  The active energy ray-curable pressure-sensitive adhesive is a pressure-sensitive adhesive that is cured by active energy rays such as an electron beam and ultraviolet rays. Hereinafter, the active energy ray-curable urethane pressure-sensitive adhesive preferably used in the present invention will be described in detail.

  Such an active energy ray-curable urethane-based pressure-sensitive adhesive is preferably obtained by curing an active energy ray-curable composition containing at least a urethane polymer.

  The urethane polymer contained in the active energy ray-curable composition preferably contains at least a polymerizable urethane polymer. As such a polymerizable urethane polymer, those having an ethylenically unsaturated group in the molecule are preferable. Here, examples of the ethylenically unsaturated group include a vinyl group, an allyl group, an acrylic group, and a methacryl group.

  The weight average molecular weight of the urethane polymer is preferably 33,000 or more, more preferably 35000 or more, and particularly preferably 38000 or more, from the viewpoint of increasing the initial adhesion of the pressure-sensitive adhesive sheet. The upper limit of the weight average molecular weight of the urethane polymer is preferably 60000 or less, more preferably 55000 or less, particularly preferably 50000 from the viewpoint of suppressing the increase in the viscosity of the active energy ray-curable composition described later and ensuring good coating properties. The following is preferred.

  As the polymerizable urethane polymer, the following polymerizable urethane polymer (A) or polymerizable urethane polymer (B) is preferably used, and the polymerizable urethane polymer (A) is particularly preferably used.

  The polymerizable urethane polymer (A) is a urethane polymer having ethylenically unsaturated groups at least at both ends of the molecule.

  The polymerizable urethane polymer (B) is a urethane polymer having a hydroxyl group at one end of the molecule and an ethylenically unsaturated group at the other end.

  More preferably, the active energy ray-curable composition contains both the polymerizable urethane polymer (A) and the polymerizable urethane polymer (B).

  The active energy ray-curable composition can contain other urethane polymers other than the above-described polymerizable urethane polymer (A) and polymerizable urethane polymer (B) as the urethane polymer. In this case, the content ratio of the other urethane polymer is preferably 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 10% by mass or less with respect to 100% by mass of the urethane polymer.

  The active energy ray-curable composition can contain a polymer other than the urethane polymer, such as an acrylic polymer, an ester polymer, and a silicon polymer. The content of the polymer other than the urethane polymer is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less with respect to 100 parts by mass of the urethane polymer. preferable.

  The polymerizable urethane polymer (A) is, for example, a urethane prepolymer (a) having an isocyanate group at the molecular terminal and a functional group capable of reacting with the isocyanate group (for example, a hydroxyl group, a carboxyl group, an amino group, an amide group, etc.) And a compound (b) having an ethylenically unsaturated group can be obtained.

  The polymerizable urethane polymer (B) is, for example, a urethane prepolymer (a) having an isocyanate group at the molecular terminal and a functional group capable of reacting with the isocyanate group (for example, a hydroxyl group, a carboxyl group, an amino group, an amide group, etc.) And a compound (b) having an ethylenically unsaturated group and a functional group (for example, hydroxyl group, carboxyl group, amino group, amide group, etc.) capable of reacting with an isocyanate group and a compound (c) having a hydroxyl group are reacted. Can be obtained.

  Moreover, in the synthesis | combination of the said polymeric urethane polymer (B), by adjusting the preparation ratio of the said compound (b) and the said compound (c), or adjusting the preparation order and preparation time, polymerizable urethane polymer (B) and the polymerizable urethane polymer (A) can be synthesized simultaneously.

  That is, the synthetic method can simultaneously produce the polymerizable urethane polymer (A) and the polymerizable urethane polymer (B) in one synthetic process. Therefore, the above synthesis method is preferably used for the synthesis of the polymerizable urethane polymer used in the present invention. All terminals of all molecules of the polymerizable urethane polymer obtained by this synthesis method are substituted with ethylenically unsaturated groups or hydroxyl groups, and the ratio of the terminals substituted with ethylenically unsaturated groups (hereinafter referred to as acrylate terminals). The ratio) is preferably 60 to 90% with respect to all terminals of the polymerizable urethane polymer.

  The acrylate terminal ratio can be calculated from the hydroxyl group value and molecular weight obtained by determining the hydroxyl group value of the polymerizable urethane polymer by a titration method or the like.

  When the acrylate terminal ratio of the polymerizable urethane polymer obtained by the above synthesis method is 60%, for example, the content ratio of the polymerizable urethane polymer (A) and the polymerizable urethane polymer (B) is 20:80 in terms of molar ratio. Become. Similarly, when the acrylate terminal ratio is 70%, the ratio is 40:60. Similarly, when the acrylate terminal ratio is 80%, the ratio is 60:40. Similarly, when the acrylate terminal ratio is 90%, the ratio is 80:20. It becomes a ratio.

  The compounds used for the synthesis of the polymerizable urethane polymer (A) and the polymerizable urethane polymer (B) will be described below.

  The urethane prepolymer (a) having an isocyanate group at the molecular end can be synthesized by reacting a polyol and an isocyanate compound. Examples of the polyol include polyester polyol, polyether polyol, polycaprolactone polyol, and polycarbonate polyol. Among these, polyester polyol, polyether polyol, and polycaprolactone polyol are preferable.

  The polyester polyol can be obtained by esterifying a polyvalent carboxylic acid and a polyhydric alcohol. Such polycarboxylic acids include adipic acid, sebacic acid, succinic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, fumaric acid, maleic acid, maleic anhydride, itacone Examples include acids, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, lactic acid, dimer acid, and the like. Of these, adipic acid, sebacic acid, pyrrolimetic acid, and dimer acid are preferable.

  Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, polyethylene glycol, polybutylene glycol, polypropylene glycol, 1,4-butanediol, 1,6 -Hexanediol, 3-methyl 1,5-pentanediol, ethylene oxide or propylene oxide adduct of bisphenol A, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, etc. can be used. Bifunctional alcohols such as 4-butanediol are preferred.

  The polyether polyol can be obtained by an etherification reaction of a polyhydric alcohol. As a polyhydric alcohol used here, the thing similar to the polyhydric alcohol used for manufacture of the said polyester polyol can be used.

  The polycaprolactone polyol is ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, ethylene oxide of bisphenol A, or Examples include propylene oxide adducts, glycerin, trimethylolpropane, trimethylolethane, and ε-caprolactone adducts of known and commonly used polyhydric alcohols such as pentaerythritol.

  Examples of the polycarbonate polyol include a dehydrochlorination reaction between the polyhydric alcohol and phosgene used in the synthesis of the polyester polyol, or a transesterification reaction between the polyhydric alcohol and diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and the like. What is obtained is mentioned.

  The isocyanate compound used for the synthesis of the urethane pre-prepolymer (a) having an isocyanate group at the molecular end includes tolylene diisocyanate, hydrogenated tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, lysine diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate. Diisocyanate compounds such as isophorone diisocyanate, xylene diisocyanate and hydrogenated xylylene diisocyanate are preferably used.

  As the urethane prepolymer (a), those having isocyanate groups at both ends of the molecule are preferable.

  Next, the compound (b) to be reacted with the urethane prepolymer (a) in order to synthesize the polymerizable urethane polymer (A) and the polymerizable urethane polymer (B) will be described. Compound (b) is a functional group capable of reacting with an isocyanate group (for example, hydroxyl group, carboxyl group, amino group, amide group, etc.) and an ethylenically unsaturated group (for example, vinyl group, allyl group, acrylic group, methacryl group, etc.) It is a compound which has this.

  Examples of the compound (b) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, butanediol mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate modified with caprolactone, glycidol di Hydroxyl group-containing (meth) acrylates such as (meth) acrylate and pentaerythritol tri (meth) acrylate, (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxy Carboxyl group-containing (meth) acrylates such as ethyl succinic acid, amino group-containing (meth) acrylates such as N, N-diethylaminoethyl (meth) acrylate, (meth) acrylamide, N, N-dimethyl (meth) acrylate Ruamido, N- butyl (meth) acrylamide, N- methylol (meth) acrylamide, containing an amide group such as N- methylol propane (meth) acrylamide (meth) acrylate. Among these, a hydroxyl group-containing (meth) acrylate compound is particularly preferably used.

  Next, the compound (c) to be reacted with the urethane prepolymer (a) in order to synthesize the polymerizable urethane polymer (B) will be described. Examples of the compound (c) include polyvalent carboxylic acids, oxycarboxylic acids, and polyhydric alcohols.

  Examples of the polyvalent carboxylic acid include adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, and fumaric acid. , Maleic acid, maleic anhydride, itaconic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, dimer acid, ethane-1,1,2-tricarboxylic acid, hexane-2,3,5 -Known and commonly used organic acids such as tricarboxylic acids are preferably used, but dicarboxylic acids are preferred from the standpoint of compatibility with other components.

  As said oxycarboxylic acid, well-known and usual organic acids, such as lactic acid, glycolic acid, trioxybutyric acid, trioxyvaleric acid, trioxyhexanoic acid, gluconic acid, are used suitably, for example.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, polyethylene glycol, polybutylene glycol, polypropylene glycol, and 1,3-butanediol. 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, bisphenol A ethylene oxide or propylene oxide adduct, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, etc. A polyhydric alcohol can be preferably used. Among them, diols such as 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, and 3-methyl-1,5-pentanediol are preferable from the viewpoint of compatibility with other components and water absorption stability. Particularly preferred.

  The active energy ray-curable composition preferably further contains a polymerizable monomer. As such a polymerizable monomer, a) a monomer having an oxygen atom-containing heterocyclic ring and b) a monomer having a phenyloxy group are preferably used from the viewpoint of increasing the initial adhesive strength of the pressure-sensitive adhesive.

  Examples of the above-mentioned monomer having an oxygen atom-containing heterocycle include monomers having an oxygen atom-containing heterocycle such as furfuryl, morpholine, caprolactan, and examples thereof include tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl ( And (meth) acrylate, N- (meth) acryloylmorpholine, vinylcaprolactam and the like.

  Examples of the above-mentioned (b) monomer having a phenyloxy group include phenoxy (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy-polyethylene glycol (meth) acrylate, and 2-hydroxy-3- Examples include phenoxypropyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate.

As the polymerizable monomer, c) a hydroxy group-containing monomer is also preferably used. Examples of such monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl (meth). Acrylate, 8-hydroxyoctyl (meth) acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate, diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, N-methylol (meth) acrylamide, 3-chloro-2-hydroxy Examples thereof include propyl (meth) acrylate, 2,2-dimethyl-2-hydroxyethyl (meth) acrylate, etc. The polymerizable monomers (a), (b), and (c) described above are monofunctional. Is preferred. Moreover, it is preferable that the polymerizable monomer used for an active energy ray curable composition is a monomer which does not have a carboxyl group.

  The polymerizable monomer includes at least one selected from a) a monomer having an oxygen atom-containing heterocyclic ring and b) a monomer having a phenyloxy group, and c) at least one selected from a hydroxy group-containing monomer. Are preferably used in combination. In this case, the ratio (mass ratio) of the total amount of a) and b) and c) is preferably in the range of 80:20 to 20:80, more preferably in the range of 70:30 to 30:70, The range of 60:40 to 40:60 is particularly preferable.

  The total use amount of the polymerizable monomer in the active energy ray-curable composition is preferably in the range of 1 to 50% by mass, preferably 2 to 40% by mass with respect to 100% by mass of the solid content of the active energy ray-curable composition. Is more preferable, and a range of 5 to 30% by mass is particularly preferable.

  In particular, from the viewpoint of increasing the initial adhesive strength of the pressure-sensitive adhesive, the total amount of the above-mentioned a) monomer having an oxygen atom-containing heterocyclic ring and b) a monomer having a phenyloxy group is based on 100 parts by mass of the urethane polymer. It is preferably 10 parts by mass or more, more preferably 12 parts by mass or more, and particularly preferably 15 parts by mass or more. The upper limit is about 40 parts by mass.

  The active energy ray-curable composition preferably further contains a polymerization initiator. Commercially available products can be widely used as such polymerization initiators, but the following polymerization initiators are preferably used. Examples include acetophenones such as diethoxyacetophenone and benzyldimethyl ketal, benzoin ethers such as benzoin and benzoin methyl ether, benzophenones such as benzophenone and methyl o-benzoylbenzoate, and hydroxy such as 1-hydroxy-cyclohexyl-phenyl-ketone. Examples include alkylphenones, thioxanthones such as 2-isopropylthioxanthone and 2,4-dimethylthioxanthone, and amines such as triethanolamine and ethyl 4-dimethylbenzoate.

  The amount of the polymerization initiator used is suitably in the range of 0.05 to 5% by mass and in the range of 0.1 to 3% by mass with respect to 100% by mass of the total solid content of the active energy ray-curable composition. preferable.

  The active energy ray-curable composition is preferably a so-called solventless type that does not substantially contain an organic solvent. Here, that the active energy ray-curable composition does not substantially contain an organic solvent means that the amount of the organic solvent contained in 100% by mass of the active energy ray-curable composition is 5% by mass or less. The amount of the organic solvent is preferably 3% by mass or less, more preferably the amount of the organic solvent is 1% by mass or less, and particularly preferably no organic solvent is contained.

  The organic solvent is a highly volatile organic solvent such as methyl ethyl ketone, methyl isobutyl ketone, toluene, butyl acetate, ethanol, and methanol, and particularly an organic solvent having a boiling point of 130 ° C. or less.

  The organic solvent does not include a liquid polymerizable monomer (for example, a low-molecular (meth) acrylate monomer used as a reactive diluent).

  By making the above-mentioned active energy ray-curable composition solvent-free, the safety and environmental performance in the production process are improved, and the residual solvent of the obtained adhesive can be greatly reduced. In addition, the solventless type is preferable because the drying process at the time of producing the pressure-sensitive adhesive sheet can be omitted, and the production process is shortened. In addition, the solvent-free type is preferable because production efficiency is improved in the production of a relatively thick adhesive sheet as in the present invention.

  In order to prevent yellowing, the active energy ray-curable composition preferably contains an antioxidant or a light stabilizer.

  As the antioxidant, a hindered phenol antioxidant and a phosphorus antioxidant are preferably used. As the light stabilizer, a monomer having a sterically hindered piperidyl group and an ethylenically unsaturated group is preferably used.

  Examples of the hindered phenol antioxidant include triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythritol-tetrakis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,6-hexanediol-bis [3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], ethylenebis (oxyethylene) bis [3- (5-t-butyl-4-hydroxy-m-tolyl) propionate], hexamethylene-bis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], isooctyl-3- 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, N, N′-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N, N′-hexamethylenebis ( 3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, diethyl [(3 5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl] phosphate, 3,5-di-tert-butyl-4-hydroxybenzyl phosphonate-diethyl ester, 3,3 ′, 3 ″ , 5,5 ′, 5 ″ -hexa-t-butyl-a, a ′, a ″-(mesitylene-2,4,6-triyl) tri-p-cresol, 1,1,3-tris ( 2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethyl) isocyanuric acid, 1,3,5- Tris (4-sec-butyl-3-hydroxy-2,6-dimethyl) isocyanuric acid, 1,3,5-tris (4-neopentyl-3-hydroxy-2,6-dimethyl) isocyanuric acid, 2,2 ′ -Methylenebis (4 -Methyl-6-t-butylphenol), 4,4'-butylidenebis (4-methyl-6-t-butylphenol), tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, Tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, polycondensate of p-chloromethylstyrene and p-cresol, polycondensate of p-chloromethylstyrene and divinylbenzene, p -An isobutylene reaction product of cresol and divinylbenzene polycondensate, and the like.

  Among the above compounds, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythritol-tetrakis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,6-hexanediol-bis [3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate], ethylenebis (oxyethylene) bis [3- (5-t-butyl-4-hydroxy-m-tolyl) propionate], hexamethylene-bis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate], isooctyl-3- (3,5-di-t-butyl-4- Hydroxyphenyl) propionate compounds such propionate are preferably used.

  Examples of phosphorus antioxidants include triphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, diphenyl octyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tetrakis (2, 4-di-t-butylphenyl) -4,4'-biphenylene phosphite, trisnonylphenyl phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphos Phyto, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4- Dicumylphenyl) pentaerythrito Ru-diphosphite, tetrakis (2,4-di-t-butylphenyl) (1,1-biphenyl) -4,4'-diylbisphosphonite, di-t-butyl-m-cresyl-phosphonite, distearyl penta Erythritol diphosphite, di (2,4-di-t-butylphenyl) -pentaerythryl diphosphite, di (2,6-di-t-butyl-4-methylphenyl) -pentaerythryl diphosphite 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-ditridecyl) phosphite, cyclic neopentanetetrayl (octadecyl phosphite), diisodecyl pentaerythritol diphosphite, 2,2-methylene bis (4,6-di-t-butylphenyl) octyl phosphite, bis (tridecyl ) Pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer, hydrogenated bisphenol A phosphite polymer, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, tetra ( Tridecyl) -4,4′-isopropylidene diphenyl diphosphite, tetraphenyl dipropylene glycol diphosphite and the like.

  Among these, triphenyl phosphites such as triphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, diphenyl octyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, diphenyl alkyl phosphite, etc. Phytes and monophenyl dialkyl phosphites are preferably used.

  A monomer having a sterically hindered piperidyl group and an ethylenically unsaturated group that can be used in the present invention will be described. The sterically hindered piperidyl group in such a monomer is one having 1 to 2 alkyl groups at the 2-position and 6-position of the piperidyl group, respectively. The ethylenically unsaturated group is an acryl group (acryloyl group), A methacryl group (methacryloyl group), a crotonoyl group, a vinyl group, an allyl group, etc., and an ethylenically unsaturated group is directly or directly at the 1-position and / or 4-position of a sterically hindered piperidyl group, or a linking group such as an oxygen atom or imino group It is a compound bound via

  Monomers having a sterically hindered piperidyl group and an ethylenically unsaturated group that are preferably used in the present invention can be represented by the following general formulas (1) and (2).

(In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ^{2 to} R ⁵ each independently represents an alkyl group having 1 to 4 carbon atoms, and R ⁶ represents a hydrogen atom or a cyano group. R ⁷ and R ⁸ each independently represents a hydrogen atom or a methyl group, and X ¹ represents an oxygen atom or an imino group.)

(Wherein R ^{12 to} R ¹⁵ each independently represents an alkyl group having 1 to 4 carbon atoms, R ¹⁶ represents a hydrogen atom or a cyano group, and R ^{17 to} R ²⁰ each independently represents a hydrogen atom or methyl) And X ² represents an oxygen atom or an imino group.

  Examples of the compound represented by the general formula (1) include 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6. -Tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4 -Cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2 , 6,6-tetramethylpiperidine and the like.

  Examples of the compound represented by the general formula (2) include 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4. -Cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine and the like.

  Among the compounds described above, the compound represented by the general formula (1) is preferable, and 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1, 2,2,6,6-pentamethylpiperidine is preferably used.

  The content ratio of the hindered phenol antioxidant, the phosphorus antioxidant, and the monomer having a sterically hindered piperidyl group and an ethylenically unsaturated group is the solid content of the active energy ray-curable composition. The range of 0.05-5 mass% is preferable with respect to the total amount of 100 mass%, and the range of 0.1-3 mass% is more preferable.

  The active energy ray curable composition may further contain a polymerization inhibitor. As such a polymerization inhibitor, hydroquinone, hydroquinone monomethyl ether, benzoquinone, pt-butylcatechol, 2,6-dibutyl-4-methylphenol and the like can be used.

  In addition, the active energy ray-curable composition includes various additives other than those described above as necessary, for example, antioxidants, antifoaming agents, leveling agents, light stabilizers, ultraviolet absorbers, anti-coloring agents, pigments, etc. Can be contained.

  The pressure-sensitive adhesive sheet made of the active energy ray-curable urethane pressure-sensitive adhesive preferably used in the present invention is formed or coated with the above-mentioned active energy ray-curable composition to a predetermined thickness, and then irradiated with active energy rays. Manufactured by curing. Specifically, the active energy ray-curable composition described above is applied to a predetermined thickness on a release treatment surface of a release sheet (eg, a release PET film), and then cured by irradiation with active energy rays. The pressure-sensitive adhesive sheet of the present invention is produced by caulking. When the pressure-sensitive adhesive sheet of the present invention is used for the close contact of each member of a display device, it is peeled off from the release film.

  Examples of the active energy rays include ultraviolet rays, electron beams, and radiation (α rays, β rays, γ rays, etc.). In practice, ultraviolet rays are simple and preferable. As the ultraviolet ray source, an ultraviolet fluorescent lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, a carbon arc lamp, or the like can be used.

  When irradiating active energy rays, it is preferable to irradiate in an atmosphere having a low oxygen concentration. Thereby, yellowing of the obtained pressure-sensitive adhesive sheet can be suppressed and can be cured efficiently.

  The oxygen concentration when irradiated with active energy rays is preferably 3000 ppm or less, more preferably 1000 ppm or less, and particularly preferably 500 ppm or less. The lower limit of the oxygen concentration is about 50 ppm from an economical viewpoint.

  As a method of reducing the oxygen concentration, a method of injecting an inert gas such as nitrogen gas and replacing it with oxygen is preferably used. In this case, it is preferable to seal as much as possible so that the outside air does not enter the active energy ray irradiating apparatus, and to blow an inert gas such as nitrogen gas therein to lower the oxygen concentration.

  In addition, as a method of irradiating active energy rays in an atmosphere having a low oxygen concentration, another release sheet (for example, a release sheet) may be formed on the active energy ray-curable composition coated on a release sheet (for example, a release PET film). A method of irradiating active energy rays in a state where oxygen is blocked by laminating a type PET film or the like) can also be preferably used.

  The pressure-sensitive adhesive sheet of the present invention preferably has a shear modulus of 0.5 MPa or less, more preferably 0.4 MPa or less, and particularly preferably 0.3 MPa or less. The lower limit of the shear modulus is preferably 0.05 MPa or more, more preferably 0.08 MPa or more, and particularly preferably 0.1 MPa or more.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. In addition, the measuring method and evaluation method in a present Example are shown below.

1) Measuring method of initial adhesion strength After the adhesive sheet prepared in this example was cut to a width of 25 mm and one release PET film was peeled off, it was pasted on a 100 μm-thick polyethylene terephthalate film and passed for 24 hours. A sample for measurement was obtained.
The other release PET film of the above measurement sample was peeled off at an ambient temperature and humidity of 23 ± 2 ° C. and 50 ± 5% RH, and held on a polyethylene glass terephthalate film on a 1.8 mm thick soda glass plate. The pressure-sensitive adhesive sheet was affixed, and a rubber roller having a weight of 2 kg was reciprocated once and pressed. After a lapse of 5 minutes after the pressure bonding, a 180 degree peel test was conducted using Tensilon RTM-100 (Orientec Co., Ltd.) at a peel rate of 300 mm / min. The measurement was performed 5 times, and the measurement data of 3 times excluding the maximum value and the minimum value were averaged. The glass plate was washed with methyl ethyl ketone and then washed with ethyl alcohol.

2) Measurement of adhesion strength after 24 hours In the same manner as described above, an adhesive sheet held on a polyethylene terephthalate film was pasted on a soda glass plate, and then the ambient temperature and humidity were 23 ± 2 ° C., 50 ± 5% RH. The adhesion was measured after standing for 24 hours. The measurement method and the average method of the measurement data are the same as the method 1).

3) Evaluation of bubble generation Using the adhesive sheet prepared in this example, the liquid crystal display panel of the mobile phone and the transparent protective plate (having a decorative layer around a 0.7 mm thick glass plate) were adhered to each other. Then, it was observed whether bubbles were generated in the vicinity of the decorative layer (thickness 20 μm black printing layer) of the transparent protective plate, and evaluated according to the following criteria.
○: No bubbles are generated.
X: Bubbles are generated.

4) Measuring method of weight average molecular weight The weight average molecular weight of the urethane polymer was measured by GPC. For measurement, WALTERS GPC-150C Plus (manufactured by Japan WALTERS) was used under the following conditions.
Detector: WALTERS 2410
・ Solvent: Tetrahydrofuran ・ Column: 2 HR4, 1 HR4E (7.5 mm × 300 mm)
・ Temperature: 40 ℃
・ Concentration: 0.2%
・ Injection volume: 100 μl
・ Flow velocity: 1.0m / m
-N number: 3.

5) Method for measuring the acrylate terminal ratio of urethane polymer The acrylate terminal ratio of the urethane polymer is calculated according to JISK-1557 by dissolving the resin in chloroform, adding acetic anhydride and titrating with KOH to calculate the hydroxyl value. The acrylate terminal ratio was calculated from the hydroxyl value and the weight average molecular weight.

<Synthesis of urethane polymer 1>
In a flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube, 97.98 parts by mass of polypropylene glycol (“Exenol 3020” manufactured by Asahi Glass Urethane Co., Ltd., number average molecular weight 3200), dibutyltin dilaurate 11 parts by mass were charged. Next, the temperature inside the system was raised to 70 ° C. while blowing nitrogen gas, and after dissolving uniformly, 7.38 parts by mass of isophorone diisocyanate was added, and the temperature was kept while stirring for 3 hours. Thereafter, 0.415 parts by mass of 2-hydroxyethyl acrylate was added while blowing oxygen gas and nitrogen gas, then 0.15 part by mass of 1,3-butanediol was added, and the mixture was kept warm for 3 hours while stirring for 30 minutes. As a result of measuring the molecular weight of each, it was confirmed that the ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) was constant at 1.5, the reaction was terminated, and urethane polymer 1 (weight average molecular weight 41500 ) The urethane polymer 1 has an acrylate terminal ratio of 80%, a polymerizable urethane polymer (A) having an ethylenically unsaturated group at both terminals of the molecule, a hydroxyl group at one terminal of the molecule, and the other terminal. The polymerizable urethane polymer (B) having an ethylenically unsaturated group is contained at 60:40 (molar ratio).

<Synthesis of urethane polymers 2-5>
In the synthesis of the urethane polymer 1, urethane polymers 2 to 5 having different molecular weights were synthesized by adjusting the amount of isophorone diisocyanate and the reaction temperature.

  The weight average molecular weight of the urethane polymer 2 was 45000, the weight average molecular weight of the urethane polymer 3 was 35000, the weight average molecular weight of the urethane polymer 4 was 30000, and the weight average molecular weight of the urethane polymer 5 was 25000. The acrylate terminal ratio of the urethane polymers 2 to 5 was adjusted to be 80% as in the urethane polymer 1.

Example 1
A pressure-sensitive adhesive sheet was prepared in the following manner.
<Preparation of solvent-free active energy ray-curable composition>
90 parts by mass of the urethane polymer 1, 14 parts by mass of 4-hydroxybutyl acrylate as a polymerizable monomer, 10 parts by mass of phenoxyethyl acrylate, and a hydroxyalkylphenone photopolymerization initiator (Ciba Specialty Chemicals Co., Ltd.) as a polymerization initiator ) "Irgacure 184") 0.7 parts by weight, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] as a hindered phenolic antioxidant 1 Parts by weight, 0.5 parts by weight of triphenyl phosphite as a phosphorus antioxidant, and 4- (meth) acryloyloxy-1,2,2 as a monomer having a sterically hindered piperidyl group and an ethylenically unsaturated group , 6,6-pentamethylpiperidine is added in an amount of 0.5 parts by mass and mixed uniformly. And a solvent-free active energy ray curable composition of the (UV curable compositions) were prepared.

<Production of pressure-sensitive adhesive sheet>
The above active energy ray-curable composition is applied onto a release PET film (Therapy (registered trademark) manufactured by Toray Film Processing Co., Ltd.) with a slit die coater, and then the oxygen concentration is increased by blowing nitrogen gas. In a state of 300 ppm, a metal halide lamp is used to irradiate with ultraviolet rays (integrated light quantity 1500 mJ / cm ² ) to form an adhesive layer, and on the adhesive layer, a release PET film (Toray Film Processing Co., Ltd. (Registered trademark)) was laminated to produce an adhesive sheet. The thickness of the obtained pressure-sensitive adhesive sheet was 175 μm (excluding the release PET film).

(Example 2)
In the preparation of the solventless active energy ray-curable composition of Example 1, a solventless active energy ray-curable composition was prepared in the same manner as in Example 1 except that the urethane polymer 1 was changed to the urethane polymer 2. Further, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

(Example 3)
<Preparation of solvent-free active energy ray-curable composition>
90 parts by mass of the urethane polymer 3, 16 parts by mass of 4-hydroxybutyl acrylate as a polymerizable monomer, 16 parts by mass of phenoxyethyl acrylate, and a hydroxyalkylphenone photopolymerization initiator (Ciba Specialty Chemicals Co., Ltd.) as a polymerization initiator ) "Irgacure 184") 0.9 parts by weight, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] as a hindered phenolic antioxidant 1 Parts by weight, 0.5 parts by weight of triphenyl phosphite as a phosphorus antioxidant, and 4- (meth) acryloyloxy-1,2,2 as a monomer having a sterically hindered piperidyl group and an ethylenically unsaturated group , 6,6-pentamethylpiperidine is added in an amount of 0.5 parts by mass and mixed uniformly. And a solvent-free active energy ray curable composition of the (UV curable compositions) were prepared.

<Production of pressure-sensitive adhesive sheet>
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the above active energy ray-curable composition was used.

(Comparative Example 1)
In the preparation of the solventless active energy ray-curable composition of Example 1, a solventless active energy ray-curable composition was prepared in the same manner as in Example 1 except that the urethane polymer 1 was changed to the urethane polymer 3. Further, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

(Comparative Example 2)
In the preparation of the solventless active energy ray-curable composition of Example 1, a solventless active energy ray-curable composition was prepared in the same manner as in Example 1 except that the urethane polymer 1 was changed to the urethane polymer 4. Further, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

(Comparative Example 3)
In the preparation of the solventless active energy ray-curable composition of Example 1, a solventless active energy ray-curable composition was prepared in the same manner as in Example 1 except that the urethane polymer 1 was changed to the urethane polymer 5. Further, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

<Evaluation>
About each adhesive sheet produced above, adhesion force and generation of bubbles were evaluated. The results are shown in Table 1.

  In Examples 1 to 3 of the present invention, the initial adhesion was 10 N / 25 mm or more, and no bubbles were generated.

  On the other hand, in Comparative Examples 1 to 3, the initial adhesion was less than 10 N / 25 mm, and bubbles were generated. In Comparative Example 1, the adhesion strength after 24 hours was 10 N / 25 mm or more, but bubbles were generated because the initial adhesion strength was less than 10 N / 25 mm. This shows that the initial adhesion is important for suppressing bubbles.

DESCRIPTION OF SYMBOLS 1 Transparent protective board 2 Adhesive sheet of this invention 3 Display panel 4 Decorating layer of a transparent protective board 5 Touch panel 6 Adhesive layer

Claims (5)

  A pressure-sensitive adhesive sheet disposed between a display panel of a display device and a transparent protective plate provided with a decorative layer on the display panel side, wherein the pressure-sensitive adhesive is a urethane-based pressure-sensitive adhesive, and soda glass An adhesive sheet having an initial adhesion to the plate of 10 N / 25 mm or more.   The pressure-sensitive adhesive sheet according to claim 1, wherein the urethane-based pressure-sensitive adhesive is an active energy ray-curable urethane-based pressure-sensitive adhesive.   The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the thickness is 50 to 1000 µm.   A display device comprising a display panel and a transparent protective plate provided with a decorative layer on the display panel side, wherein the display panel and the transparent protective plate are interposed via the adhesive sheet according to claim 1. A display device in which the surface provided with the decorative layer is closely attached.   A display device in which a display panel, a touch panel, and a transparent protective plate provided with a decorative layer on the display panel side are arranged in this order, and the touch panel via the adhesive sheet according to claim 1 And the surface provided with the decorative layer of the transparent protective plate.

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