Adhesive sheet laminate

Abstract

Provided is an adhesive sheet laminate in which appearance defects do not readily occur despite having an adhesive layer having a high storage modulus and a large thickness. This adhesive sheet laminate comprises an adhesive layer and a release sheet (A), the release sheet (A) being bonded so as to be in contact with at least one surface of the adhesive layer, the thickness of the release sheet (A) being at least 0.25 times the thickness of the adhesive layer, the 180 DEG release force (Sa) between the release sheet (A) and the adhesive layer being 0.2-0.5 N / 50 mm, and the thickness of the release sheet (A) being at least 0.25 times the thickness of the adhesive layer. The storage modulus of the adhesive layer at 23 DEG C is 5 * 104 Pa or more, the thickness of the adhesive layer is 120 [mu] m or more, and T (minute) measured by a separator creep test is Tgt; 40).

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive sheet laminate. BACKGROUND

[0002] Conventionally, input devices used in combination with display devices such as liquid crystal displays (LCDs) and / or display devices such as touch panels are widely used. In these display devices and / or input devices, transparent adhesive sheets are used in the use of bonding optical members, and adhesive sheets are also used in the bonding of display devices and input devices.

[0003] An adhesive sheet generally has an adhesive layer. In the state where the adhesive layer is exposed, deterioration of the adhesive layer sometimes occurs during storage and / or transportation, or the adhesive layer is sometimes attached to other materials. Therefore, the adhesive sheet is generally stored and transported, etc. in the state where the adhesive layer is protected with a release sheet. The release sheet is, for example, a member formed by providing a release agent layer on a base material, and is sometimes referred to as a so-called separator. The release sheet is used, for example, by being directly bonded to the adhesive layer. Hereinafter, the laminate in which the release sheet is bonded to the adhesive layer is described as an "adhesive sheet laminate". In addition, the expression "adhesive sheet" refers to the adhesive layer without the release sheet, and particularly refers only to the adhesive layer.

[0004] In the bonding process of a member using an adhesive sheet, low peeling force when peeling the separator from the adhesive layer is important for the efficiency of the bonding work. If the release sheet is heavy (i.e., if the force required for peeling is large), measures such as reducing the peeling speed are required, and the efficiency of the bonding work decreases. From this viewpoint, technologies for improving the peeling properties of the release sheet have been widely studied. For example, Patent Literature 1 discloses an adhesive film in which the peeling properties of the separator are excellent and the workability is good.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2009-242767 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] On the other hand, an adhesive sheet bears a bending stress due to sheet bending caused by a passage of a conveying roll and / or curling caused by winding of a product, etc. during the manufacturing process. For an adhesive sheet in which the storage modulus of the adhesive layer is high and the thickness is large (for example, an adhesive sheet having an adhesive layer with a thickness of 120 μm or more), if the peeling force of the release sheet in the adhesive sheet laminate is low, the following problems sometimes occur due to this: displacement occurs between the release sheet and the adhesive layer, and lifting (appearance defect) occurs in the adhesive sheet.

[0010] That is, for an adhesive sheet laminate in which the adhesive layer has a high storage modulus and a large thickness, if the release force of the release sheet is simply reduced to improve the releasability, appearance defects are easily caused (if the adhesive sheet has a low storage modulus, the adhesive sheet follows the deformation even if it is bent, so it is not easy to cause release floating). This means that in an adhesive sheet laminate with a release sheet, the releasability of the release sheet and the suppression of appearance defects are in a trade-off relationship with each other. In particular, for an adhesive sheet laminate provided with an adhesive layer having a high storage modulus and a large thickness, it is difficult to achieve both improvement in releasability and suppression of appearance defects. However, depending on the type of use, there are cases where an adhesive sheet having a high storage modulus and a large thickness is required, and therefore, even for an adhesive sheet laminate provided with an adhesive layer having a high storage modulus and a large thickness, it is extremely important to establish a technology for releasability of the release sheet and suppression of appearance defects.

[0011] The present application was completed in view of the above circumstances, and aims to provide an adhesive sheet laminate in which appearance defects are not easily caused even though it is provided with an adhesive layer having a high storage modulus and a large thickness.

[0012] Approach to solving the problem

[0013] The present inventors and others have repeatedly conducted intensive research in order to achieve the above object, and as a result, it has been found that the above object can be achieved by combining an adhesive layer having prescribed properties with a release sheet, and thus the present application has been completed.

[0014] That is, the present application includes, for example, the subject matter described in the following items.

[0015] Item 1

[0016] An adhesive sheet laminate comprising an adhesive layer and a release sheet A,

[0017] The aforementioned release sheet A is attached in contact with at least one face of the aforementioned adhesive layer,

[0018] The aforementioned release sheet A has a thickness of 0.25 times or more of the thickness of the aforementioned adhesive layer,

[0019] The 180° release force Sa between the aforementioned release sheet A and the aforementioned adhesive layer is 0.2 to 0.5 N / 50 mm,

[0020] The aforementioned adhesive layer has a storage modulus of 5 x 10 4 Pa or more at 23°C,

[0021] The aforementioned adhesive layer has a thickness of 120 μm or more,

[0022] The adhesive sheet laminate has a T (minutes) of T > 40 according to the following diaphragm creep test.

[0023] <Membrane Creep Test>

[0024] An adhesive sheet laminate (width 25 mm x length 25 mm) was produced by adhering a film to the side of the aforementioned adhesive layer opposite the aforementioned release sheet A, and the side of the aforementioned film of the adhesive sheet laminate was fixed to a SUS304 plate using a double-sided tape to produce a test sample. That is, a test sample was produced in which the aforementioned release sheet A, the aforementioned adhesive layer, the aforementioned film, the aforementioned double-sided tape, and the aforementioned SUS304 plate were sequentially laminated. For this test sample, the time required until the release sheet A and the adhesive layer were peeled apart after a shear load of 9.8 N was applied to the release sheet A at 23°C was measured, and this time was set as T (minutes).

[0025] Item 2

[0026] The adhesive sheet laminate according to item 1, wherein a release sheet B is adhered to the side of the aforementioned adhesive layer opposite the side to which the aforementioned release sheet A is adhered,

[0027] The aforementioned release sheet B has a thickness of 0.2 times or more the thickness of the aforementioned adhesive layer,

[0028] The 180° peeling force Sb between the aforementioned release sheet B and the aforementioned adhesive layer is 1.5 times or more the aforementioned peeling force Sa.

[0029] Item 3

[0030] The adhesive sheet laminate according to item 1 or 2, wherein the aforementioned adhesive layer is a cured product of a curable energy ray adhesive.

[0031] Effects of the Invention

[0032] The adhesive sheet laminate of the present application does not easily develop appearance defects even though it has an adhesive layer with a high storage modulus and a large thickness. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a schematic diagram illustrating the case where a membrane creep test is performed. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments of the present application will be described in detail. Note that in the present specification, the expressions “containing” and “including” include the concepts of “consisting essentially of’ and “consisting of’.

[0035] The adhesive sheet laminate of the present application includes an adhesive layer and a release sheet A. In the adhesive sheet laminate of the present application, the aforementioned release sheet A is attached in contact with at least one face of the aforementioned adhesive layer, the thickness of the aforementioned release sheet A is 0.25 times or more of the thickness of the aforementioned adhesive layer, and the 180° peeling force Sa between the aforementioned release sheet A and the aforementioned adhesive layer is 0.2 to 0.5 N / 50 mm.

[0036] In addition, in the adhesive sheet laminate of the present application, the storage modulus of the aforementioned adhesive layer at 23°C is 5 x 10 4 Pa or more, and the thickness of the aforementioned adhesive layer is 120 μm or more. Furthermore, T (minutes) of the adhesive sheet laminate of the present application measured according to the prescribed diaphragm creep test is T > 40.

[0037] The adhesive sheet laminate of the present application is not prone to appearance defects even though it has an adhesive layer having a high storage modulus and a large thickness. In particular, the 180° peeling force Sa of the adhesive sheet laminate of the present application is 0.2 to 0.5 N / 50 mm, and thus peeling is also easy, and the efficiency of the attaching work is excellent. That is, the adhesive sheet laminate of the present application is excellent in peeling properties and is not prone to appearance defects even though it has an adhesive layer having a high storage modulus and a large thickness.

[0038] In the present specification, the "adhesive sheet laminate of the present application" refers to a laminate in which a release sheet A is attached to an adhesive layer, and in addition, the expression "adhesive sheet" refers to an adhesive layer that does not have a release sheet, and in particular, refers only to an adhesive layer.

[0039] (Adhesive layer)

[0040] In the adhesive sheet laminate of the present application, the adhesive layer is only required to have a storage modulus at 23°C of 5 x 10 4 Pa or more and a thickness of 120 μm or more, and there is no particular limitation on the kind thereof.

[0041] For example, the adhesive layer preferably contains an acrylic polymer, and more preferably has a crosslinked structure. Therefore, the adhesive layer is preferably formed of a cured product of a variety of adhesive compositions containing an acrylic polymer. Among them, in order to make the adhesive layer have a thickness, a cured product of a radiation-curable adhesive composition is preferred.

[0042] The adhesive composition contains at least a main agent containing an acrylic polymer, and in addition, contains a crosslinking agent, a multifunctional monomer, a photopolymerization initiator, and the like described later.

[0043] The kind of the acrylic polymer contained in the main agent is not particularly limited, and for example, widely known acrylic polymers widely used in conventional adhesive sheets can be widely cited.

[0044] The acrylic polymer is not particularly limited in kind as long as it is a polymer composed of (meth)acrylic monomer units. Note that the (meth)acrylic monomer unit refers to a structural unit formed by polymerization of a (meth)acrylic monomer.

[0045] As the (meth)acrylic monomer unit, a (meth)acrylate unit can be given. The (meth)acrylate can be, for example, a (meth)acrylate having a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, or a (meth)acrylate having an aromatic ring. In the case where the (meth)acrylate has a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, the number of carbon atoms thereof can be, for example, 1 to 20, preferably 1 to 15, and more preferably 2 to 10. In the case where the (meth)acrylate has an aromatic ring, the number of carbon atoms thereof can be, for example, 5 to 20, and preferably 6 to 10. As specific examples of the (meth)acrylate monomer, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid t-butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid isopropyl ester, (meth)acrylic acid isooctyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid benzyl ester, and the like can be given.

[0046] As the (meth)acrylic monomer unit, in addition to the aforementioned (meth)acrylate unit, a monomer unit having a carboxyl group, a monomer unit having a hydroxyl group can be included. As the monomer having a carboxyl group, (meth)acrylic acid can be given. As the monomer having a hydroxyl group, for example, (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 3-hydroxypropyl ester, (meth)acrylic acid 4-hydroxybutyl ester, (meth)acrylic acid 6-hydroxyhexyl ester, (meth)acrylic acid 5-hydroxypentyl ester, (meth)acrylic acid 2-hydroxybutyl ester, (meth)acrylic acid 2-hydroxy-3-phenoxypropyl ester, (meth)acrylic acid 2,2-dimethyl-2-hydroxyethyl ester, (meth)acrylic acid 3-chloro-2-hydroxypropyl ester, (meth)acrylic acid 2-hydroxy-3-phenoxypropyl ester, (meth)acrylic acid 8-hydroxyoctyl ester, and the like (meth)acrylic acid hydroxyalkyl ester, and the like can be given.

[0047] The (meth)acrylic monomer unit constituting the acrylic polymer can be one kind alone, or two or more kinds. That is, the acrylic polymer can be a homopolymer, or a copolymer, and more preferably a copolymer. For example, the acrylic polymer can be a copolymer of one or more kinds of (meth)acrylate and one or more kinds of monomer having a carboxyl group.

[0048] In the case where the acrylic polymer contains monomer units having a carboxyl group and / or monomer units having a hydroxyl group, the total content ratio thereof in the acrylic polymer is preferably 0.1 to 40% by mass, more preferably 0.5 to 35% by mass. The acrylic polymer preferably contains 40% by mass or more, more preferably 50% by mass or more, further preferably 55% by mass or more, particularly preferably 60% by mass or more of the aforementioned (meth)acrylate ester unit.

[0049] The weight average molecular weight of the acrylic polymer is not particularly limited, and for example, from the viewpoint that a decrease in adhesive strength does not easily occur in the adhesive sheet, it can be set to 1 million to 20 million, and more preferably to 2 million to 10 million. Note that the weight average molecular weight referred to in the present application means a polystyrene conversion weight average molecular weight measured by a gel permeation chromatography (GPC) method.

[0050] The GPC device used in the GPC method is not particularly limited, and a commercially available GPC measuring machine, such as LC-2000 Plus series manufactured by Japan Spectroscopic Co., Ltd., can be used, and as a detector, RI-2031 Plus, UV-2075 Plus, or the like can be used. In this case, for example, a GPC column obtained by connecting four of "Shodex KF801", "Shodex KF803L", "Shodex KF800L", and "Shodex KF800D" manufactured by Showa Denko K.K. is used. The column temperature can be set to 40°C. Tetrahydrofuran is used as an eluent, and the measurement is performed at a flow rate of 1.0 ml / minute. In general, a standard curve can be prepared using a standard polystyrene, and the weight average molecular weight (Mw) can be obtained by polystyrene conversion.

[0051] The acrylic polymer can be produced, for example, by polymerizing a monomer mixture for forming each structural unit using a publicly known polymerization method. As the polymerization method, for example, solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, or the like can be employed. Note that the ratio of each structural unit in the acrylic polymer corresponds to the use ratio of each monomer used at the time of polymerization. The kind of solvent and / or polymerization initiator used in the polymerization is also not particularly limited, and for example, a solvent and / or polymerization initiator used in the production of a publicly known acrylic polymer can be used.

[0052] In the adhesive composition, the main agent can contain a monofunctional monomer in addition to the above-described acrylic polymer. In this case, the main agent can be in the form of a solution (serum) in which the acrylic polymer is dissolved in the monofunctional monomer or in the form of a partially bulk-polymerized product in which the monofunctional monomer solution is partially bulk-polymerized by heat and / or light. Note that, in the case where the acrylic polymer is a copolymer, the monofunctional monomer contained in the main agent can be a mixture of the same monomers as those constituting the acrylic polymer. In this case, the ratio of each monomer in the mixture can be the same as the ratio of each monomer constituting the acrylic polymer, but is not limited thereto.

[0053] In the case where the main agent is a partially bulk-polymerized product, the polymer fraction is not particularly limited. The polymer fraction refers to the proportion (mass %) of the resin component with respect to the total mass of the resin component (acrylic polymer, etc.) and the monomer. The polymer fraction can be, for example, 1 to 80 mass %, preferably 5 to 50 mass %.

[0054] The main agent preferably consists only of the acrylic polymer and the monofunctional monomer.

[0055] The adhesive composition can contain a crosslinking agent. As the crosslinking agent, for example, a functional group reaction-type crosslinking agent and / or a multifunctional monomer can be given. As the functional group reaction-type crosslinking agent, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a chelate-based crosslinking agent, a carbodiimide-based crosslinking agent, and the like can be given. In addition, the multifunctional monomer can be, for example, a compound having two or more polymerizable double bonds in the molecule. The number of polymerizable double bonds of the multifunctional monomer is two or more, preferably two or more and less than five, and more preferably two or more and less than four.

[0056] The type of the isocyanate crosslinking agent is not particularly limited, and a publicly known compound can be widely used. As the isocyanate crosslinking agent, a polyisocyanate such as toluene diisocyanate, chlorophenyl diisocyanate, diphenylmethane diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and xylylene diisocyanate; an alicyclic isocyanate such as cyclopentylene diisocyanate and cyclohexylene diisocyanate; and an aromatic isocyanate such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 4,4'-diphenylmethane diisocyanate can be given. The isocyanate crosslinking agent can be used alone or in combination with two or more different types. In addition, it is more preferable to use a 3-functional derivative such as an adduct, a urethane, and a biuret of the above-described diisocyanate as the isocyanate crosslinking agent.

[0057] The type of the epoxy crosslinking agent is not particularly limited, and a publicly known compound can be widely used. As the epoxy crosslinking agent, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexanone, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, and the like can be mentioned.

[0058] The type of the chelate crosslinking agent is not particularly limited, and an aluminum chelate, a titanium chelate, a zirconium chelate, and the like can be mentioned.

[0059] The carbodiimide crosslinking agent is not particularly limited, and a compound having a carbodiimide group in the molecule is not particularly limited, and a monocarbodiimide, a polycarbodiimide, and the like can be mentioned.

[0060] As the multifunctional monomer, for example, as a 2-functional monomer (a monomer having two polymeric double bonds), polyethylene glycol diacrylate, polypropylene diacrylate, alkyl diacrylate, polytetramethylene glycol diacrylate, polypropylene glycol diacrylate, dioxane diacrylate, tricyclodecane diacrylate, fluorene diacrylate can be mentioned. In addition, as the multifunctional monomer, as a 3-functional or more monomer, alkoxylated trimethylolpropane triacrylate, alkoxylated glycerol triacrylate, caprolactone-modified isocyanurate triacrylate, pentaerythritol acrylate, alkoxylated pentaerythritol acrylate, (alkoxylated) pentaerythritol acrylate, (alkoxylated) bis-trimethylolpropane acrylate, (alkoxylated) di-pentaerythritol acrylate, (ethoxylated) polyglycerol acrylate, and the like can be mentioned.

[0061] The multifunctional monomer can have a bisphenol skeleton in 1 molecule. As the multifunctional monomer, for example, bisphenol A diglycidyl ether diacrylate, propoxylated bisphenol A diacrylate, bisphenol F diglycidyl ether diacrylate, and the like can be mentioned.

[0062] The multifunctional monomer can be used, for example, a commercially available product. As the commercially available product, 2-functional polyethylene glycol acrylate, "A-200" (polyethylene glycol #200 diacrylate), "A-400" (polyethylene glycol #400 diacrylate) of the NK Ester series manufactured by Shin Nakamura Chemical Co., Ltd., a 3-functional monomer M310 (trimethylolpropane PO-modified triacrylate), a 3-functional monomer M321 (trimethylolpropane propylene oxide-modified triacrylate) manufactured by Toagosei Co., Ltd., a 2-functional monomer M211B (bisphenol A EO-modified diacrylate) manufactured by Toagosei Co., Ltd., and the like can be mentioned.

[0063] In the case where the adhesive composition contains a multifunctional monomer, the adhesive composition is cured by irradiation with active energy rays, so that the main agent can form a crosslinked structure, whereby the adhesive sheet is likely to have excellent adhesion.

[0064] The content of the crosslinking agent in the adhesive composition is not particularly limited, and for example, the adhesive composition can contain 10 parts by mass or less of the crosslinking agent, more preferably 5 parts by mass or less, relative to 100 parts by mass of the aforementioned main agent. In addition, the adhesive composition preferably contains 0.01 parts by mass or more of the crosslinking agent, more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the aforementioned main agent. In the case where the adhesive composition contains the crosslinking agent, one kind of the crosslinking agent alone or two or more kinds in combination can be used.

[0065] (Photo-polymerization initiator)

[0066] The adhesive composition can contain a photo-polymerization initiator. As the photo-polymerization initiator, for example, a known photo-polymerization initiator can be widely used, of which a benzophenone-based photo-polymerization initiator or an acyloxyphosphine-based photo-polymerization initiator is preferred.

[0067] As the benzophenone-based initiator, specifically, diethoxybenzophenone, benzoin dimethyl ketal, oligomer (2-hydroxy-2-methyl-1-[4-(1-methylethenyl) phenyl] propenone], 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, and the like can be mentioned. As the benzoin ether-based initiator, specifically, benzoin, benzoin methyl ether, and the like can be mentioned.

[0068] As the acyloxyphosphine-based initiator, specifically, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide, and the like can be mentioned.

[0069] As the photo-polymerization initiator, in addition, a benzoin ether-based initiator, a benzophenone-based initiator, a hydroxyalkyl phenone-based initiator, a thioxanthone-based initiator, an amine-based initiator, and the like can be mentioned.

[0070] The content of the photo-polymerization initiator in the adhesive composition is not particularly limited, and for example, the adhesive composition can contain 0.01 to 5 parts by mass of the photo-polymerization initiator, more preferably 0.05 to 1 parts by mass, relative to 100 parts by mass of the aforementioned adhesive composition. In the case where the adhesive composition contains the photo-polymerization initiator, one kind of the photo-polymerization initiator alone or two or more kinds in combination can be used.

[0071] The adhesive composition preferably contains the aforementioned main agent containing an acrylic polymer and a monofunctional monomer, a crosslinking agent, and a photopolymerization initiator. In addition, the adhesive composition can also contain a silane coupling agent, a solvent, and the like, and in addition, a dye and / or a pigment can also be added for the purpose of coloring.

[0072] The method of forming the adhesive layer is not particularly limited, and for example, a publicly known method can be widely employed. In the case of forming the adhesive layer using the aforementioned adhesive composition, for example, the adhesive layer can be formed by curing the adhesive composition using a publicly known method. The adhesive layer is a cured product of the adhesive composition. Specifically, the following procedures can be provided: a procedure of applying the adhesive composition on a substrate to form a coating film; and a procedure of irradiating the coating film with active energy rays to obtain a cured product of the adhesive composition. Thus, the adhesive layer formed by curing the adhesive composition can be formed.

[0073] The application of the adhesive composition can be performed using a publicly known coating device. As the coating device, for example, a doctor blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a microgravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, and the like can be mentioned.

[0074] As to the substrate to which the adhesive composition is to be applied, various substrates such as a resin-made substrate, a glass-made substrate, and the like can be applied, and in particular, in the present application, as the substrate, a release sheet A or a release sheet B described later can be mentioned. By sandwiching the adhesive layer with a pair of release sheets, a double-sided adhesive sheet laminate can be easily manufactured. In addition, instead of the release sheet, a film which has not been subjected to a release treatment, for example, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyethylene film, a polypropylene film, a polyarylate film, a polyester film, and the like can be formed.

[0075] The thickness of the adhesive composition after the application can be appropriately set according to the thickness of the target adhesive layer. After the formation of the coating film, a heating treatment and / or a drying treatment can be performed on the coating film as necessary.

[0076] The procedure of irradiating the coating film with active energy rays can employ the same procedure as a publicly known method. In the procedure, the photopolymerization initiator in the adhesive composition generates radicals by the active energy rays, and similarly, the components having polymerizability in the adhesive composition (for example, the monomers, the multifunctional monomers, and the like in the adhesive composition) are initiated / polymerized by the generated radicals, thereby becoming a polymerized cured product. Thus, the adhesive layer can be formed, and the adhesive force can also be improved.

[0077] As the active energy ray, ultraviolet rays, electron beams, visible rays, X-rays, ion rays, and the like can be given, and can be appropriately selected depending on the photopolymerization initiator contained in the adhesive layer. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferred, and ultraviolet rays are particularly preferred. As the light source of the ultraviolet rays, for example, chemical lamps, LEDs, high-pressure mercury lamps, low-pressure mercury lamps, ultrahigh-pressure mercury lamps, metal halide lamps, carbon arcs, xenon arcs, electrodeless ultraviolet lamps, and the like can be used. The irradiation power of the ultraviolet rays is preferably such that the cumulative light amount becomes 100 to 10,000 mJ / cm 2 , more preferably such that the cumulative light amount becomes 200 to 5,000 mJ / cm 2 .

[0078] The thickness of the adhesive layer can be appropriately set depending on the use, and is preferably 125 μm or more, more preferably 150 μm or more, and is preferably 1,000 μm or less.

[0079] The adhesive layer can be any of a single layer structure and a layered structure, and is preferably a single layer structure.

[0080] The storage modulus of the adhesive layer at 23°C is preferably 5 x 10 4 Pa or more. When the storage modulus of the adhesive layer at 23°C is less than 5 x 10 4 Pa, the adhesive sheet cannot have sufficient hardness, and the use can be limited. The storage modulus of the adhesive layer at 23°C is preferably 5 x 10 4 Pa or more, more preferably 7 x 10 4 Pa or more, and is preferably 1 x 10 7 Pa or less.

[0081] (Release sheet A)

[0082] The release sheet A can be, for example, a substrate on which a release-treated layer is formed. The substrate can be, for example, a resin film and paper, and the like. The resin film can be, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyarylate, polyester, and the like, and the paper can be, for example, polyethylene laminated paper, polypropylene laminated paper, clay-coated paper, resin-coated paper, glassine paper, and the like.

[0083] The release-treated layer can be formed of various resins, and can be, for example, silicone-based resins, long-chain alkyl-based resins, fluorine-based resins, and the like.

[0084] The release treatment layer used in the release sheet is desirably a silicone-based release agent. The silicone release layer is any of a heat condensation type, a heat addition type, and an ultraviolet curing type, and is formed by curing. As the heat condensation type, a substance obtained by reacting polydimethylsiloxane and polymethylhydrogenosiloxane using an organotin catalyst or the like can be given. As the heat addition type, a substance obtained by reacting polydimethylsiloxane containing a vinyl group and polymethylhydrogenosiloxane by platinum catalysis or the like can be given. In addition, as the ultraviolet curing type release agent, a release agent obtained by polymerizing a modified silicone containing an epoxy group by photocationic polymerization or the like can be given. In order to adjust the releasability, an MQ resin and / or a vinyl group-containing silicone resin, a silicone oil, a silane coupling agent, a leveling agent, or the like can be added to the silicone-based release agent. In addition, in order to adjust the release force, the thickness can also be adjusted.

[0085] As for the release sheet A, the substrate is preferably polyethylene terephthalate, and the release treatment layer is preferably a silicone-based release agent. By this combination, both the 180° release force Sa and T measured according to the diaphragm creep test easily become in the desired range.

[0086] The release sheet A can use a commercially available product, and examples thereof can include "75E-KF" manufactured by Fujimori Kogyo Co., Ltd., "50-TKA(09)" manufactured by Toyobo Co., Ltd., "75-J02" manufactured by NIPPA Co., Ltd., "NS-75-SUM" manufactured by Nakamoto Packs Co., Ltd., and the like.

[0087] The thickness of the release sheet A is 0.25 times or more the thickness of the aforementioned adhesive layer. By being set to the thickness, appearance defects of the adhesive sheet laminate can be suppressed. Specifically, even if sheet bending and / or curling due to product winding occur during the adhesive sheet manufacturing process, the release sheet and the adhesive layer are less likely to be offset, and the occurrence of floating in the adhesive sheet can be suppressed. In the case where the thickness of the release sheet A is less than 0.25 times the thickness of the aforementioned adhesive layer, the release sheet and the adhesive layer are likely to be offset, and floating occurs in the adhesive sheet, which becomes a cause of appearance defects.

[0088] The thickness of the release sheet A is preferably 0.25 times or more, more preferably 0.28 times or more, and is preferably 1 time or less the thickness of the aforementioned adhesive layer.

[0089] (Adhesive sheet laminate)

[0090] The adhesive sheet laminate of the present application includes at least an adhesive layer and a release sheet A, and the aforementioned release sheet A is attached in contact with at least one face of the aforementioned adhesive layer. More specifically, the aforementioned release sheet A is directly attached to one face of the aforementioned adhesive layer.

[0091] The 180° peeling force Sa between the aforementioned release sheet A and the aforementioned adhesive layer in the adhesive sheet laminate is 0.2 to 0.5 N / 50 mm (i.e., 0.2 N / 50 mm or more and 0.5 N / 50 mm or less). If the 180° peeling force Sa is less than 0.2 N / 50 mm, there is a possibility that the release sheet A is peeled off or shifted by chance, or, in the case where the adhesive sheet is bent, the shift of the release sheet A is easily caused, and the cause of appearance failure is easily caused. If the 180° peeling force Sa exceeds 0.5 N / 50 mm, the peeling force is too large, and thus, it is difficult to peel off the release sheet A, and the efficiency of the attaching work using the adhesive sheet is reduced.

[0092] The 180° peeling force Sa between the aforementioned release sheet A and the aforementioned adhesive layer can be measured as follows. A film is attached to the side of the aforementioned adhesive layer opposite to the aforementioned release sheet A, and an adhesive sheet laminate (width 50 mm x length 50 mm) is produced. The film side of the adhesive sheet laminate is fixed to a SUS304 plate with double-sided tape, and a test sample is produced. That is, a test sample in which the aforementioned release sheet A, the aforementioned adhesive layer, the aforementioned film, the aforementioned double-sided tape, and the aforementioned SUS304 plate are sequentially layered is produced. After that, after standing for 1 day in an environment of atmospheric pressure, a temperature of 23°C, and a humidity of 50%, the 180-degree peeling of the release sheet A is performed at a speed of 0.3 m / minute with an island-seisakusho AGX-500NX, and the peeling force at this time is taken as the 180° peeling force Sa (N / 50 mm). Note that the kind of film used in the measurement of the 180° peeling force Sa is not particularly limited, and, for example, the same kind as the film contained in the test sample S used in the diaphragm creep test described later can be used.

[0093] T (minutes) of the adhesive sheet laminate of the present application measured according to the diaphragm creep test is T > 40. The diaphragm creep test is performed by the following method.

[0094] <Diaphragm Creep Test>

[0095] A film is attached to the side of the aforementioned adhesive layer opposite to the aforementioned release sheet A, and an adhesive sheet laminate (width 25 mm x length 25 mm) is produced. The aforementioned film side of the adhesive sheet laminate is fixed to a SUS304 plate with double-sided tape, and a test sample is produced. That is, a test sample in which the aforementioned release sheet A, the aforementioned adhesive layer, the aforementioned film, the aforementioned double-sided tape, and the aforementioned SUS304 plate are sequentially layered is produced. For this test sample, the time required until the release sheet A and the adhesive layer are peeled after a shear load of 9.8 N is applied to the release sheet A at 23°C is measured, and this time is taken as T (minutes). Refer to Figure 1 A more detailed measurement procedure for the diaphragm creep test is described.

[0096] Figure 1This is a schematic diagram illustrating the process of conducting a diaphragm creep test. The diaphragm creep test involves fabricating... Figure 1 The test sample S shown is used for this purpose. Test sample S can be prepared, for example, according to the following steps: First, prepare an adhesive sheet laminate consisting of a release liner A, adhesive layer 1, and film 2. Cut it into 25mm × 90mm pieces. Then, slowly peel the release liner A from one end along its length from the interface of the adhesive layer, leaving only 25mm × 25mm of film 2 and adhesive layer 1 remaining at the other end (the 25mm × 90mm portion of release liner A remains). Install a metal ring (not shown) on the portion C (end portion) of release liner A where film 2 and adhesive layer 1 are not adhered. As the metal ring, prepare a triangular ring, 35mm on one side, made by bending a 3mm diameter SUS304 material. Wrap this ring around the side end of release liner A and secure it with a stapler.

[0097] On the other hand, a SUS304 board with a thickness of 1mm, a width of 30mm, a length of 50mm, and an opening H is prepared at the top. Figure 1 A test sample S was prepared by attaching double-sided tape 3 (marked "SUS304") to the film 2 side of the adhesive sheet laminate without blocking the holes H of the SUS304 plate, and then using a roller to adhere the tape 3. The test sample S was then hung on a hook via the holes H of the SUS304 plate. A 1 kg weight G was suspended from the metal ring at 23°C, thereby applying a shear load of 9.8 N vertically to the release sheet A. The time taken until the release sheet A peeled off from the adhesive layer 1 was measured. This time was recorded as T (minutes) based on the diaphragm creep test. Therefore, T (minutes) refers to the time from when the 1 kg weight G was just suspended from the metal ring until the release sheet A was completely peeled off from the adhesive layer 1.

[0098] The type of film 2 used in the preparation of test sample S is not particularly limited; for example, it can be a release sheet or a resin sheet other than a release sheet. If film 2 is a release sheet, it can be the same as release sheet A, or it can be a different type of release sheet. Alternatively, it can be release sheet B, which will be described later. The type of resin sheet is also not particularly limited; for example, known resin sheets such as polyethylene terephthalate (PET) can be widely used.

[0099] For the adhesive sheet laminate of the present invention, when the aforementioned T is 40 minutes or less, the adhesive sheet laminate is prone to appearance defects. That is, when the aforementioned T is 40 minutes or less, there is a concern that the release liner A may accidentally peel off or become misaligned, or, in the case of bending of the adhesive sheet, misalignment of the release liner A may easily occur, which may become a cause of appearance defects.

[0100] The aforementioned T of the adhesive sheet laminate of the present application is preferably 41 minutes or more, more preferably 43 minutes or more, further preferably 60 minutes or more, still further preferably 90 minutes or more, and particularly preferably 120 minutes or more. In addition, the adhesive sheet laminate of the present application preferably has the aforementioned T of 2880 minutes or less. The aforementioned T can also be 1200 minutes or less.

[0101] The adhesive sheet laminate of the present application can have other layers as long as it includes the adhesive layer and the release sheet A. For example, the adhesive sheet laminate of the present application can have a release sheet B attached to the surface of the adhesive layer opposite to the surface to which the release sheet A is attached. That is, the adhesive sheet laminate of the present application can have a structure in which the release sheet A is attached to one surface of the adhesive layer and the release sheet B is attached to the other surface. The release sheet A and the release sheet B can be the same or different.

[0102] As one preferred mode of the adhesive sheet laminate of the present application, there can be mentioned a mode in which a release sheet B is attached to the surface of the aforementioned adhesive layer opposite to the surface to which the aforementioned release sheet A is attached, the aforementioned release sheet B has a thickness of 0.2 times or more of the thickness of the aforementioned adhesive layer, and the 180° release force Sb between the aforementioned release sheet B and the aforementioned adhesive layer is 1.5 times or more of the aforementioned release force Sa.

[0103] The release sheet B can similarly to the release sheet A use a substrate formed with a release-treated layer. The release sheet B can use a commercially available product, and for example, there can be mentioned "MRV#50V04", "MRV#100 V06T", "MRV#75V06", "MRF#75", and the like manufactured by Mitsubishi Chemical Corporation.

[0104] By making the thickness of the release sheet B 0.2 times or more of the thickness of the aforementioned adhesive layer, it is more easily possible to suppress appearance defects of the adhesive sheet laminate, and in addition, it is easily possible to selectively peel off only one release sheet at the time of peeling off the release sheet, and it is easily possible to suppress the so-called carry-over peeling phenomenon.

[0105] The thickness of the release sheet B is preferably 0.2 times or more, more preferably 0.25 times or more, and in addition, it is preferably 2 times or less of the thickness of the aforementioned adhesive layer.

[0106] In the case where the 180° release force Sb between the aforementioned release sheet B and the aforementioned adhesive layer is 1.5 times or more of the aforementioned release force Sa, it is more easily possible to suppress the aforementioned carry-over peeling phenomenon. The 180° release force Sb between the aforementioned release sheet B and the aforementioned adhesive layer is preferably 1.7 times or more, more preferably 2 times or more, and in addition, it is preferably 20 times or less, more preferably 10 times or less of the aforementioned release force Sa.

[0107] The method for measuring the 180° peeling force Sb between the aforementioned release sheet B and the aforementioned adhesive layer is the same method as that for measuring the 180° peeling force Sa.

[0108] In the case where the adhesive sheet laminate of the present application has the release sheet A on one face of the adhesive layer and the release sheet B on the other face, the release sheet A functions as a light release film and the release sheet B functions as a heavy release film. Therefore, in the case of using the adhesive sheet laminate, first, the release sheet A is peeled off to expose the adhesive layer, and the exposed adhesive layer is attached to an object. Next, the release sheet B is peeled off to expose the adhesive layer, and other members can be attached to the exposed face.

[0109] The adhesive sheet laminate of the present application can provide an adhesive sheet having a high storage modulus and a thickness. In particular, by making the adhesive force between the release sheet A and the adhesive layer be within a prescribed range, the release sheet is easily peeled off, and thus the efficiency of the attachment work is good. Furthermore, even in the case where the adhesive sheet laminate generates a shear stress caused by bending and / or displacement, displacement and / or peeling of the release sheet A is not easily generated, and as a result, appearance defects are suppressed.

[0110] In addition, the 180° peeling force Sa is 0.2 to 0.5 N / 50 mm, and thus the release sheet is also easily peeled off, and the efficiency of the attachment work is also good.

[0111] In summary, the adhesive sheet laminate of the present application has an adhesive layer having a high storage modulus and a large thickness, and has excellent releasability and is not easily subjected to appearance defects.

[0112] The adhesive sheet laminate of the present application can be used for the attachment of an adherend. For example, as the adherend, various optical members can be given, and glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate (PMMA), polyethylene naphthalate, a cyclic olefin polymer, cellulose triacetate, polyimide, a cellulose acylate, and the like can be given. Among these, the adherend is particularly preferably composed of at least one selected from the group consisting of glass, polycarbonate, and PMMA.

[0113] Furthermore, as the optical member, each component member of a touch panel and / or an image display device, and the like can be given. As the component member of the touch panel, an ITO film having an ITO film provided on a transparent resin film, an ITO glass having an ITO film provided on the surface of a glass plate, a transparent conductive film having a conductive polymer coated on a transparent resin film, a hard coat film, a fingerprint-resistant film, and the like can be given. As the component member of the image display device, for example, an antireflection film, an alignment film, a polarizing film, a phase difference film, a brightness enhancement film, and the like used in a liquid crystal display device can be given. In addition, the adhesive sheet laminate of the present application can be used for the attachment of a liquid crystal module to a module such as a touch panel module.

[0114] The configurations (properties, structures, functions, and the like) described in each of the embodiments of the present application can be arbitrarily combined in determining the inventions contained in the present application. That is, the present application includes all the subjects formed by all the combinations of the configurations capable of being combined described in the present specification.

[0115] Example

[0116] Hereinafter, the present application will be described more specifically by examples, but the present application is not limited in the manner of the examples.

[0117] (Production Example 1)

[0118] In a 2L flask equipped with a stirrer, a nitrogen inlet tube, a condenser tube, and a thermometer, 600 g of 2-ethylhexyl acrylate, 100 g of cyclohexyl methacrylate, 300 g of 4-hydroxybutyl acrylate, and 0.1 g of n-dodecyl mercaptan were put in, and then 0.15 g of AIBN was put in, and the reaction was performed for 30 minutes while controlling the heat generation, and then the flask was cooled to room temperature. The additional monomers were put in the flask in such a manner that the monomer ratio described above was obtained, and the adjustment was performed in such a manner that the solid content concentration became 30%. By the above operation, a slurry containing an acrylic polymer having a solid content concentration of 20 mass% and a weight average molecular weight of about 800,000 was obtained (primary agent).

[0119] (Production Example 2)

[0120] In a 2L flask equipped with a stirrer, a nitrogen inlet tube, a condenser tube, and a thermometer, 600 g of butyl acrylate, 100 g of isobutyl methacrylate, 400 g of 4-hydroxybutyl acrylate, and 0.2 g of n-dodecyl mercaptan were put in, and then 0.2 g of AIBN was put in, and the reaction was performed for 30 minutes while controlling the heat generation, and then the flask was cooled to room temperature. The additional monomers were put in the flask in such a manner that the monomer ratio described above was obtained, and the adjustment was performed in such a manner that the solid content concentration became 20%. By the above operation, a slurry containing an acrylic polymer having a solid content concentration of 30 mass% and a weight average molecular weight of about 600,000 was obtained (primary agent).

[0121] (Example 1)

[0122] To 100 parts by mass of the slurry obtained in Production Example 1, 0.3 parts by mass of "A-200: polyethylene glycol #200 diacrylate" manufactured by Shin-Nakamura Chemical Industries, Ltd. as a crosslinking agent and 0.4 parts by mass of "Omniard 651" manufactured by IGM Resin Co., Ltd. as a photopolymerization initiator were mixed by planetary stirring to prepare an adhesive composition. The adhesive composition was applied to a release sheet B ("MRV #50V04" manufactured by Mitsubishi Chemical Corporation, thickness 50 μm) in a manner such that the thickness became 200 μm, the width became 150 mm, and the length became 250 mm to form a coating film, and further, a release sheet A ("75E-KF" manufactured by Fujimori Kogyo Co., Ltd., thickness 75 μm) was overlapped thereon to obtain a laminate. The laminate was irradiated with a chemical lamp at a light intensity of 5 mW / cm 2 , so that the cumulative light quantity became 240 mJ / cm 2 , and then irradiated with a high-pressure mercury lamp at a light intensity of 150 mW / cm 2 , so that the cumulative light quantity became 2000 mJ / cm 2 . Thus, an adhesive sheet laminate was obtained, in which the thickness of the adhesive layer was 200 μm and the storage modulus at 23°C was 9.1 x 10 4 Pa.

[0123] (Production Example 2)

[0124] The slurry was changed to the slurry obtained in Production Example 2, 0.5 parts by mass of "A-400: polyethylene glycol #400 diacrylate" manufactured by Shin-Nakamura Chemical Industries, Ltd. as a crosslinking agent and 0.4 parts by mass of "Omniard 651" manufactured by IGM Resin Co., Ltd. as a photopolymerization initiator were mixed by planetary stirring to prepare an adhesive composition. The release sheet A was changed to "50-TKA (09)" manufactured by Toyobo Co., Ltd. (thickness 50 μm), the release sheet B was changed to "MRV #100V06T" manufactured by Mitsubishi Chemical Corporation (thickness 100 μm), and otherwise, an adhesive sheet laminate was obtained by the same method as in Example 1, in which the thickness of the adhesive layer was 150 μm and the storage modulus at 23°C was 1.5 x 10 5 Pa.

[0125] (Production Example 3)

[0126] The release sheet A was changed to "J02" manufactured by NIPPA Co., Ltd. (thickness 75 μm), the release sheet B was changed to "MRF #75" manufactured by Mitsubishi Chemical Corporation (thickness 75 μm), and otherwise, an adhesive sheet laminate was obtained by the same method as in Example 1, in which the thickness of the adhesive layer was 200 μm and the storage modulus at 23°C was 9.1 x 10 4 Pa.

[0127] (Production Example 4)

[0128] The release sheet A was changed to "NS-75-SUM" (thickness 75 μm) manufactured by Nakamoto Packs Co., Ltd., the release sheet B was changed to "MRV#100V06" (thickness 100 μm) manufactured by Mitsubishi Chemical Corporation, and the thickness of the adhesive layer was set to 250 μm, and otherwise, by the same method as in Example 2, an adhesive sheet laminate was obtained, in which the storage modulus at 23°C was 1.5 x 10 5 Pa.

[0129] (Comparative Example 1)

[0130] The release sheet A was changed to "J01" (thickness 75 μm) manufactured by NIPPA Co., Ltd., the release sheet B was changed to "MRV#100V06T" (thickness 100 μm) manufactured by Mitsubishi Chemical Corporation, and otherwise, by the same method as in Example 1, an adhesive sheet laminate was obtained, in which the thickness of the adhesive layer was 200 μm, and the storage modulus at 23°C was 9.1 x 10 4 Pa.

[0131] (Comparative Example 2)

[0132] The release sheet A was changed to "MRQ#75" (thickness 75 μm) manufactured by Mitsubishi Chemical Corporation, the release sheet B was changed to "MRV#100V06" (thickness 100 μm) manufactured by Mitsubishi Chemical Corporation, and otherwise, by the same method as in Example 1, an adhesive sheet laminate was obtained, in which the thickness of the adhesive layer was 200 μm, and the storage modulus at 23°C was 9.1 x 10 4 Pa.

[0133] (Comparative Example 3)

[0134] The slurry was changed to the slurry obtained in Production Example 2, the release sheet A was changed to "NS-50-TA" (thickness 50 μm) manufactured by Nakamoto Packs Co., Ltd., the release sheet B was changed to "MRV#100V06T" (thickness 100 μm) manufactured by Mitsubishi Chemical Corporation, and otherwise, by the same method as in Example 1, an adhesive sheet laminate was obtained, in which the thickness of the adhesive layer was 150 μm, and the storage modulus at 23°C was 1.5 x 10 5 Pa.

[0135] (Comparative Example 4)

[0136] The slurry was changed to the slurry obtained in Production Example 1, the release sheet A was changed to "TKA (07)" (thickness 38 μm) manufactured by Toray Industries, Inc., the release sheet B was changed to "MRV#100V06T" (thickness 100 μm) manufactured by Mitsubishi Chemical Corporation, and otherwise, by the same method as in Example 1, an adhesive sheet laminate was obtained in which the thickness of the adhesive layer was 175 μm and the storage modulus at 23°C was 9.1 x 10 4 Pa.

[0137] (Comparative Example 5)

[0138] The release sheet A was changed to "MFAS" (thickness 38 μm) manufactured by Toray Industries, Inc., the release sheet B was changed to "MRF#75" (thickness 75 μm) manufactured by Mitsubishi Chemical Corporation, and otherwise, by the same method as in Example 1, an adhesive sheet laminate was obtained in which the thickness of the adhesive layer was 200 μm and the storage modulus at 23°C was 9.1 x 10 4 Pa.

[0139] (Evaluation Method)

[0140] <Storage Modulus>

[0141] The storage modulus at 23°C of the adhesive layer was measured using a dynamic viscoelasticity device (trade name: MCR301) manufactured by Anton Paar Japan. The adhesive layer was laminated to 1 mm, and a sample punched out in φ8 mm was attached to a fixed jig. The value of the storage modulus G' of the adhesive layer at 23°C was read under the conditions of a frequency of 1 Hz and a temperature increase rate of 5°C / minute from -70°C to 120°C.

[0142] <180° Peeling Force Sa>

[0143] The face of the release sheet B of the adhesive sheet laminate formed of the release sheet A, the adhesive layer, and the release sheet B obtained in the example was attached to a SUS304 plate using a double-sided tape at a width of 50 mm and a length of 50 mm, and then, pressure-bonded with a roller. Thereafter, it was left to stand for 1 day under the conditions of atmospheric pressure, a temperature of 23°C, and a humidity of 50%. The 180-degree peeling of the release sheet A was performed at a speed of 0.3 m / minute using an AGX-500NX manufactured by Shimadzu Corporation, and the peeling force at that time was taken as the 180° peeling force Sa (N / 50 mm).

[0144] <180° Peeling Force Sb>

[0145] In the example, the release sheet A of the adhesive sheet laminate formed by release sheet A, adhesive layer, and release sheet B was peeled off from the adhesive layer. The adhesive layer was then attached to an SUS304 board with a width of 50 mm and a length of 50 mm, and pressed with a roller. Afterward, it was left to stand for one day at atmospheric pressure, temperature of 23°C, and humidity of 50%. For the test sample obtained therefrom, the release sheet B was peeled off at a speed of 0.3 m / min using a Shimadzu AGX-500NX. The peeling force at this point was taken as the 180° peeling force Sb (N / 50 mm).

[0146] <Diaphragm Creep Test>

[0147] use Figure 1 The test sample S shown was subjected to a diaphragm creep test. The test sample S was prepared using the same steps as described above. The test sample S was hung on a hook through a hole in a SUS304 plate. A 1 kg weight was suspended from the aforementioned metal ring at 23°C, thereby applying a shear load of 9.8 N vertically to the release tab A. The time taken until the release tab A peeled off from the adhesive layer 1 was measured. This time was taken as T (minutes) based on the diaphragm creep test.

[0148] <Appearance>

[0149] The adhesive sheet laminates prepared in the examples and comparative examples were placed on a workbench immediately after fabrication, and a φ30mm, 130mm long, 1kg weight was placed horizontally perpendicular to the length direction of the laminate. Then, the laminate ends parallel to the weight were grasped with both hands and lifted 100mm off the workbench along with the weight. The left and right ends of the laminate were then moved up and down ten times, ensuring the weight on the flexed laminate did not move significantly to the left or right. This operation was performed on both sides of the laminate, and then it was left to stand at room temperature for one day with the weight removed. Afterward, the appearance was observed. If wrinkles, bends, or lifting caused by peeling of the release sheet from the adhesive layer were observed, the appearance was recorded as defective (×); otherwise, it was recorded as good (〇).

[0150] <Stripping along with the product>

[0151] The adhesive sheet laminate prepared in the examples and comparative examples was cut into 100mm × 100mm pieces using a cutting machine. Then, the release sheet was slowly peeled off from the release sheet A side of the cut piece. At this time, if the adhesive sheet peeled off more than 5mm from the end of the release sheet B as the release sheet A was peeled off, it was recorded as defective (×), and if it did not peel off, it was recorded as good (〇).

[0152] [Table 1]

[0153]

[0154] The results of the constitution and the storage modulus, the Sa value, the Sb value of the adhesive sheet laminates obtained in the examples and the comparative examples are shown in Table 1, and the results of the appearance evaluation and the with-tape peeling evaluation of the adhesive sheet laminates are also shown.

[0155] No appearance defect was observed in the adhesive sheet laminates obtained in Examples 1 to 4, in contrast to which appearance defects were observed in the adhesive sheet laminates obtained in the comparative examples. Thus, the adhesive sheet laminate containing the prescribed release sheet A did not easily develop appearance defects even though it had an adhesive layer with a high storage modulus and a large thickness.

[0156] Explanation of Reference Signs

[0157] S: Test sample

[0158] A: Release sheet

[0159] 1: Adhesive layer

[0160] 2: Film

[0161] H: Hole

[0162] 3: Double-sided tape 3

[0163] G: Weight

Claims

1. An adhesive sheet laminate comprising an adhesive layer and a release sheet A, The release tab A is attached in such a manner that it contacts at least one side of the adhesive layer. The thickness of the release tab A is at least 0.25 times the thickness of the adhesive layer. The 180° peel force Sa between the release tab A and the adhesive layer is 0.2~0.5N / 50mm. The energy storage modulus of the adhesive layer at 23°C is 5×10⁻⁶. 4 Pa or above The thickness of the adhesive layer is 120 μm or more. The T value of the adhesive sheet laminate, as measured according to the diaphragm creep test below, is T>40, where T is in minutes. Diaphragm creep test: A film is adhered to the adhesive layer on the side opposite to the release liner A to create an adhesive sheet laminate (25mm wide × 25mm long). The film side of the adhesive sheet laminate is fixed to an SUS304 board using double-sided tape to create a test sample. That is, a test sample is created by sequentially stacking the release liner A, the adhesive layer, the film, the double-sided tape, and the SUS304 board. For this test sample, the time required for the release liner A to peel off from the adhesive layer after applying a shear load of 9.8N at 23°C is measured. This time is denoted as T, where T is in minutes.

2. The adhesive sheet laminate according to claim 1, wherein, A release sheet B is attached to the surface of the adhesive layer opposite to the surface to which the release sheet A is attached. The thickness of the release tab B is at least 0.2 times the thickness of the adhesive layer. The 180° peel force Sb between the release tab B and the adhesive layer is more than 1.5 times the peel force Sa.

3. The adhesive sheet laminate according to claim 1 or 2, wherein, The adhesive layer is a cured product of an active energy radiation-cured adhesive.

Images