Adhesive layer, laminate, and decorative sheet

Abstract

To provide an adhesive layer which hardly causes delamination of a decorative sheet after molding and heat treatment after the molding, and can exhibit good moldability.SOLUTION: An adhesive layer formed on a resin base material has adhesive force of 0.4 N / mm or more, and tensile elastic modulus of 0.8 MPa or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive layer, a laminate, and a decorative sheet. [Background technology]

[0002] Decorative sheets have traditionally been used to decorate or protect the surfaces of molded articles such as plastic parts and interior / exterior components. For example, the application of metallic luster to the surface of molded articles to impart a sense of luxury and brilliance is used for a variety of molded articles, including exterior parts such as bumpers and front grilles mounted on vehicles such as automobiles, motorcycles, airplanes, and trains, interior parts such as dashboards, housings for electronic devices, office automation equipment, home appliances, landline phones, mobile phones, etc., key chains, switch input panels, key tops for pushbutton switches, authentication ID cards, sundry goods cases, cosmetic containers, and architectural panels.

[0003] One example of a method for producing a molded article using a decorative sheet is to place the decorative sheet in an injection mold and perform insert molding. As a decorative sheet to be used in this insert molding, for example, Patent Document 1 proposes a moldable decorative sheet that is made of a laminate in which a metal thin film layer is laminated on a base film, and a colored resin layer is laminated directly on the base film side of the metal thin film layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-255666 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 aims to provide a moldable decorative sheet that has a deep metallic luster, is easy to manufacture, and maintains visibility even after long-term use. However, no study is made on the adhesion of the decorative sheet after it has been molded into a molded product.

[0006] That is, in molding methods such as insert molding, after molding or subsequent heat treatment, Insufficient adhesion of the decorative sheet can cause it to separate from the injected resin (delamination), resulting in poor appearance and preventing the decorative sheet from fulfilling its various functions (e.g., protective function).

[0007] In view of the above, the present invention has been made in consideration of the above, and aims to provide an adhesive layer that, when used in a decorative sheet to form a molded body, is less likely to cause delamination of the decorative sheet after molding or subsequent heat treatment, and can exhibit good moldability. [Means for solving the problem]

[0008] The present inventors have found that the above problems can be solved by the invention described below, and have completed the invention.

[0009] [1] An adhesive layer formed on a resin substrate, the adhesive layer having an adhesive strength of 0.4 N / mm or more as measured by the following method (1) and a tensile modulus of elasticity of 0.8 MPa or more as measured by the following method (2). Method (1): Adhesion strength measurement method A polycarbonate sheet of 0.2 mm thickness made of polycarbonate resin with a Tg of 150 to 160°C was used as the resin substrate, and the adhesive layer of 0.01 mm thickness was formed on top of it. A polyester film of 0.1 mm thickness made of polyester resin with a Tg of 70 to 80°C was then attached to form a 15 mm wide test piece. The polycarbonate sheet side of the test piece was folded back and set in a tensile tester. The test piece was then held at 140°C for 2 minutes, and the peel strength between the polycarbonate sheet and the polyester film was measured using the tensile tester, and this was taken as the adhesive strength. Method (2): Tensile modulus measurement method A measurement sheet having a thickness of 0.05 mm is prepared using a single layer of the adhesive alone, and this is cut into a 15 mm wide test piece. The test piece is set in a tensile tester so that the gripping distance is 150 mm, and after holding at 140°C for 2 minutes, the tensile modulus is measured using the tensile tester. [2] The adhesive layer according to [1], wherein the adhesive layer is a cured product of an adhesive containing a polyester resin and a diisocyanate compound. [3] The adhesive layer according to [1] or [2], wherein the thickness of the adhesive layer is 1 to 30 μm. [4] A laminate having an adhesive layer and a resin film layer in this order on at least one side of a resin substrate, wherein the adhesive layer is the adhesive layer described in any one of [1] to [3]. [5] The laminate according to [4], wherein the resin substrate has a glass transition temperature of 120°C or higher. [6] The laminate according to [4] or [5], wherein the resin film is a polyester-based resin. [7] The laminate according to any one of [4] to [6], wherein the ratio (Ta / Tf) of the thickness (Ta) of the adhesive layer to the thickness (Tf) of the resin film layer is 0.005 to 1.5. [8] A decorative sheet comprising the laminate according to any one of [4] to [7]. [Effects of the Invention]

[0010] According to the present invention, an adhesive layer can be provided which, when used in a decorative sheet to form a molded article, is less likely to cause delamination of the decorative sheet after molding or subsequent heat treatment, and can exhibit good moldability. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, one embodiment of the present invention (the present embodiment) will be described. [Adhesive layer] The adhesive layer according to this embodiment is an adhesive layer formed on a resin substrate, and has an adhesive strength of 0.4 N / mm or more and a tensile modulus of elasticity of 0.8 MPa or more. If the adhesive strength is less than 0.4 N / mm, when the decorative sheet is used to form a molded article, delamination of the decorative sheet occurs after molding or after subsequent heat treatment. The adhesive strength is preferably 0.4 to 4.0 N / mm, and more preferably 0.8 to 3.5 N / mm. If the tensile modulus is less than 0.8 MPa, when the decorative sheet is used to form a molded article, delamination of the decorative sheet occurs after molding or subsequent heat treatment. The tensile modulus is preferably 0.8 to 6.0 MPa, and more preferably 0.9 to 4.0 MPa.

[0012] The adhesive strength can be measured by the following method. That is, a polycarbonate sheet 0.2 mm thick made of polycarbonate resin with a Tg of 150 to 160°C was used as the resin substrate, a 0.01 mm thick adhesive layer was formed on top of it, and a polyester film 0.1 mm thick made of polyester resin with a Tg of 70 to 80°C was attached as the resin film to form a 15 mm wide test piece, and the polycarbonate sheet side of the test piece was folded back and set in a tensile tester. The test piece was then held at 140°C for 2 minutes, and the peel strength between the polycarbonate sheet and the polyester film was measured using the tensile tester, and this was taken as the adhesive strength.

[0013] The tensile modulus can be measured by the following method. That is, a measurement sheet with a thickness of 0.05 mm is prepared using a single layer of adhesive only, and this is used to form a 15 mm wide test piece. The test piece is set in a tensile tester so that the gripping distance is 150 mm, and after holding at 140°C for 2 minutes, the tensile modulus is measured using the tensile tester.

[0014] The adhesive strength can be adjusted by, for example, increasing the amount of crosslinking agent added, increasing the thickness of the adhesive layer, using an adhesive with many functional groups (increasing the acid value, particularly the hydroxyl value), or by selecting the crosslinking agent. The tensile modulus can be adjusted by, for example, increasing the amount of crosslinking agent added, using an adhesive with many functional groups (increasing the acid value and hydroxyl value), or selecting the crosslinking agent.

[0015] In order to obtain good adhesive strength and tensile modulus, the adhesive layer is preferably a cured product of an adhesive containing a combination of a polyester resin and a diisocyanate compound, or a combination of a water-based urethane resin and a hydrophilic multifunctional epoxy. As the polyester resin, polyester polyol is exemplified, and polyester polyol is preferred in terms of high flexibility, low melting point or softening point, and improved processability.

[0016] Examples of water-based urethane resins include those containing a urethane resin and water. The urethane resin is dispersible in water, and examples thereof include urethane resins having hydrophilic groups such as anionic groups, cationic groups, and nonionic groups, and urethane resins forcibly dispersed in water with an emulsifier.

[0017] The water-soluble epoxy compound or polymer used as the raw material for the hydrophilic multifunctional epoxy is not particularly limited as long as it has at least three, preferably four or more, epoxy groups per molecule. Examples include glycidyl ethers, glycidyl esters, and glycidyl amines. Examples of glycidyl ethers include sorbitol polyglycidyl ethers, polyglycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, diglycerol polyglycidyl ethers, glycerol polyglycidyl ethers, and trimethylolpropane polyglycidyl ethers. Some of these have low water solubility, and in some cases, a water-soluble organic solvent may be used in combination to form an aqueous solution.

[0018] Examples of polyester polyols include polyols obtained by polycondensation of dicarboxylic acids (adipic acid, succinic acid, maleic acid, phthalic acid, etc.) and glycols (ethylene glycol, propylene glycol, 1,4-butylene glycol, 1,6-hexane glycol, neopentyl glycol, etc.).

[0019] As the diisocyanate compound, of the monomer type, biuret type, isocyanurate type, and adduct type, the isocyanurate type is more suitable, and an isocyanurate of tolylene diisocyanate, an isocyanurate of hexamethylene diisocyanate (HDI), an isocyanurate of isophorone diisocyanate, etc. are preferred, with the isocyanurate of hexamethylene diisocyanate being more preferred. As isocyanurates of hexamethylene diisocyanate, products such as Coronate HX, Coronate HXR, and Coronate HK are commercially available from Tosoh Corporation.

[0020] When the adhesive uses a polyester polyol as the main component and a diisocyanate compound as the curing agent, it is preferable to use the adhesive with a solid mass ratio (curing agent / main component) of, for example, 0.03 to 0.25 (preferably 0.07 to 0.2, more preferably 0.1 to 0.19). Furthermore, when a water-based urethane resin is used as the base agent and a hydrophilic multifunctional epoxy is used as the curing agent, the solid mass ratio (curing agent / base agent) is preferably, for example, 0.03 to 0.25 (preferably 0.04 to 0.2, more preferably 0.05 to 0.1).

[0021] The adhesive may also contain various additives, such as viscosity modifiers, leveling agents, antigelling agents, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, and nucleating agents.

[0022] The adhesive layer according to the present embodiment is formed by applying an adhesive to a resin substrate, laminating the resin substrate with a resin film, and then curing the adhesive. The curing method is not particularly limited, and a known method can be used appropriately depending on the type of adhesive.

[0023] The thickness of the adhesive layer is preferably 1 to 30 μm, more preferably 3 to 30 μm, from the viewpoint of preventing peeling during molding, heating steps after molding, durability tests, etc. From the viewpoint of suppressing surface roughness such as citron peel, which is specific to polyester-based adhesives, the thickness is more preferably 4 to 20 μm, even more preferably 5 to 15 μm.

[0024] [Laminate] The laminate according to this embodiment is a laminate having an adhesive layer and a resin substrate layer in this order on at least one surface of a resin film, and the adhesive layer is the adhesive layer of the present invention described above.

[0025] In terms of molding techniques such as in-mold molding, insert molding, vacuum / compressed air molding, and injection molding, the glass transition temperature (Tg) of the resin film constituting the resin substrate layer is preferably 120°C or higher, and more preferably 120 to 160°C. The glass transition temperature can be measured, for example, by DSC. Examples of resin substrates include polycarbonate (PC), acrylic resin (PMMA), and acrylonitrile butadiene styrene resin (ABS), with polycarbonate being preferred from the standpoints of transparency and impact resistance of the molded product.

[0026] The thickness of the resin substrate layer is preferably 100 μm or more from the viewpoint of the thermal effect of the molten resin on the adhesive when the molten resin is poured during injection molding, and is preferably 300 μm or less from the viewpoint of facilitating deep drawing when forming by vacuum molding or the like, and therefore is more preferably 100 to 300 μm.

[0027] In addition, from the viewpoint of the adhesive following the irregularities, the surface roughness Ra of the resin substrate layer on the adhesive layer side is preferably 0.01 to 0.05 μm, and more preferably 0.01 to 0.03 μm. The surface roughness Ra can be measured using a surface roughness measuring instrument: SE1700α (manufactured by Kosaka Laboratory Co., Ltd.).

[0028] Furthermore, the tensile modulus of elasticity in each of the MD and TD directions of the resin substrate layer measured in an atmosphere of 23°C and 50% RH is preferably 1900 to 2300 MPa, more preferably 2050 to 2150 MPa. By having the tensile modulus of elasticity of 1900 to 2300 MPa, deformation due to pressure during molding can be suppressed. The tensile modulus can be measured using a Tensilon universal testing machine RTI-1310 manufactured by A&D Co., Ltd.

[0029] The resin film according to this embodiment can be made of polycarbonate (PC), polyester-based resin, acrylic resin (PMMA), acrylonitrile-butadiene-styrene resin (ABS), etc., but polyester-based resin is preferred from the viewpoint of freedom in adding design features.

[0030] From the viewpoint of formability and designability, the thickness of the resin film is preferably 25 to 150 μm, and more preferably 25 to 125 μm.

[0031] In this embodiment, the ratio (Ta / Tf) of the thickness of the adhesive layer (Ta) to the thickness of the resin film layer (Tf) is preferably 0.005 to 1.5, more preferably 0.006 to 1.2, even more preferably 0.009 to 0.25, and particularly preferably 0.04 to 0.15. By keeping Ta / Tf at 0.005 to 1.5, peeling can be suppressed during heating steps and durability tests during and after molding.

[0032] The resin film layer preferably has a tensile modulus of elasticity in each of the MD and TD directions measured in an atmosphere of 23°C and 50% RH of 3000 to 5500 MPa, more preferably 3500 to 5000 MPa. A tensile modulus of elasticity of 3500 to 5000 MPa can suppress deformation due to pressure during molding.

[0033] [Decorative sheet] The decorative sheet according to this embodiment includes the laminate of the present invention described above. The laminate of the present invention can be suitably used as a decorative film by appropriately subjecting it to known treatment. In this embodiment, a printed layer may be provided on at least one surface of the laminate. The printed layer refers to a layer for imparting decoration such as coloring, a pattern, a wood grain finish, a metallic finish, or a pearl finish.

[0034] The method for forming the printed layer is not particularly limited as long as it does not impair the effects of the present invention. For example, coating or printing can be used. For example, coating methods such as roll coating, gravure coating, and comma coating, as well as printing methods such as gravure printing and screen printing can be used.

[0035] Examples of resins used in the printing layer include polyester resins, polyolefin resins, acrylic resins, urethane resins, fluorine-based resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate copolymer resins, ethylene-vinyl acetate copolymer resin copolymers, etc. Furthermore, there are no particular restrictions on the colorant used in the printing layer, and it can be appropriately selected from dyes, inorganic pigments, organic pigments, etc., taking into consideration dispersibility in the resin, etc. From the viewpoint of color tone retention and design, the thickness of the printed layer is preferably 1 to 100 μm, and more preferably 2 to 50 μm.

[0036] The decorative sheet according to this embodiment can be produced, for example, by using the laminate of the present invention and a molding method such as insert molding or vacuum / pressure molding. Resins used in insert molding are not particularly limited, and examples include polybutadiene resins, polystyrene resins, polypropylene resins, acrylic resins, polyacrylonitrile-styrene copolymer resins, polyacrylonitrile-butadiene-styrene copolymer resins, polycarbonate resins, and polyacrylonitrile-ethylene propylene-styrene copolymer resins.

[0037] Furthermore, the resin used in vacuum and compressed air molding is not particularly limited, and examples thereof include polybutadiene resins, polystyrene resins, polypropylene resins, acrylic resins, polyacrylonitrile-styrene copolymer resins, polyacrylonitrile-butadiene-styrene copolymer resins, polycarbonate resins, and polyacrylonitrile-ethylene propylene-styrene copolymer resins.

[0038] The decorative sheet according to this embodiment can be used, for example, as interior or exterior materials for vehicles such as automobiles; building materials such as window frames and door frames; interior materials for building materials such as walls, floors and ceilings; housings for home appliances such as television sets and air conditioners; and exterior materials for smartphones. [Example]

[0039] The present invention will be described in more detail below with reference to the following examples, but the present invention is not limited to these examples.

[0040] [Example 1] (material) Resin substrate: Polycarbonate (glass transition temperature 150°C, surface roughness Ra 0.3 μm, tensile modulus of elasticity measured in the MD and TD directions in an atmosphere of 23°C and 50% RH: 1700 MPa, thickness 200 μm, Teijin Limited, Panlite PC-2151) Adhesive A: Main agent (polyester resin, Toyo-Morton Co., Ltd. TM-K51) and hardener (HDI isocyanurate, Tosoh Corporation Coronate HX) in a solids mass ratio of 100:15 Resin film: Polyester resin film (Cosmoshine A4360 manufactured by Toyobo Co., Ltd., glass transition point 79°C, surface roughness Ra 0.06 μm, tensile modulus of elasticity measured in the MD and TD directions at 23°C and 50% RH: 3800 MPa and 4900 MPa, respectively, thickness 100 μm)

[0041] (Measurement of tensile modulus of adhesive layer) Using adhesive A, a single layer of adhesive A alone, 0.05 mm thick, was applied to a PET separator using an applicator, dried, and laminated to the separator to create a 15 mm wide test piece. The test piece was set in a tensile tester with a grip distance of 150 mm and held at 140°C for 2 minutes, after which the tensile modulus was measured using the tensile tester. The results are shown in Table 1.

[0042] (Method for measuring adhesive strength) The resin substrate (Panlite PC-2151 manufactured by Teijin Limited) described above was used, and the adhesive layer described above with a thickness of 0.01 mm was formed on the resin substrate. The resin film described above was then laminated onto the adhesive layer to form a 15 mm wide test piece. The resin substrate side of the test piece was folded back and set in a tensile tester. The test piece was then held at 140°C for 2 minutes, and the peel strength between the polycarbonate sheet and the resin film was measured using the tensile tester, and this was taken as the adhesive strength.

[0043] Double-sided laminate Adhesive A was applied to one side of a resin substrate using a gravure coater, and a resin film was laminated on top of that. Adhesive A was also applied to one side of another resin substrate using a gravure coater, and this was then laminated to the resin film side of the laminated resin substrate and resin film. The adhesive was cured by heating at 45°C for 120 hours, producing a double-sided laminate with adhesive layers (10 μm thick on both sides) formed on both sides.

[0044] (Delamination evaluation) The double-sided laminate was set in a mold and molded using a thermoplastic resin. The injection molding machine used was a ROBOSHOT α-S510iA manufactured by FANUC Corporation. The thermoplastic resin used for injection molding was polycarbonate resin (product name: Iupilon N-5) manufactured by Mitsubishi Engineering Plastics Corporation. The resin temperature during injection molding was 300°C, the injection pressure was 243 MPa, and the mold temperature was 100°C, and insert molding was performed to produce a molded body.

[0045] After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 1. The evaluation criteria were as follows: A is the best, followed by B, C, D, E, and F. A, B, and C are acceptable. Evaluation indicators A: There was no lifting or peeling due to delamination. B: There was some lifting or peeling, but the amount was less than 5 mm. C: There was some lifting or peeling of 5 mm or more at the edge (lifting or peeling occurred at one edge). D: There was a lot of lifting or peeling of 5 mm or more at the edges (lifting or peeling occurred on both ends). E: Lifting or peeling was observed at the edges and in parts other than the edges. F: Lifting or peeling was observed in many places.

[0046] After insert molding, the product was heat treated for 24 hours at a temperature of 85°C and a relative humidity of 85%, simulating an in-vehicle reliability test (durability test), and then the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 1. The evaluation criteria were as described above.

[0047] [Example 2] (adhesive layer) Using the following adhesive B, various measurements were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0048] Adhesive B: Main agent (water-based urethane resin, Hydran WLS-201 manufactured by DIC Corporation) and curing agent (multifunctional epoxy, Deconal EX614B manufactured by Nagase ChemteX Corporation) in a solid mass ratio of 100:5.46

[0049] (Laminate) Double-sided laminate A double-sided laminate was produced in the same manner as in Example 1 using adhesive B.

[0050] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 1. The evaluation indexes were as described above.

[0051] Furthermore, the adhesive layer and the resin film were visually observed for adhesion after heat treatment for 24 hours at a temperature of 85°C and a relative humidity of 85% in the same manner as in Example 1. The results are shown in Table 1. The evaluation criteria were as described above.

[0052] [Example 3] (adhesive layer) Using the following adhesive C, various measurements were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0053] Adhesive C: Main agent (water-based urethane resin, Hydran WLS-201 manufactured by DIC Corporation) and curing agent (multifunctional epoxy, Deconal EX512 manufactured by Nagase ChemteX Corporation) in a solid mass ratio of 100:6.77

[0054] (Laminate) Double-sided laminate A double-sided laminate was produced in the same manner as in Example 1 using adhesive C.

[0055] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 1. The evaluation indexes were as described above.

[0056] Furthermore, the adhesive layer and the resin film were visually observed for adhesion after heat treatment for 24 hours at a temperature of 85°C and a relative humidity of 85% in the same manner as in Example 1. The results are shown in Table 1. The evaluation criteria were as described above.

[0057] [Comparative Example 1] (adhesive layer) Using the following adhesive D, various measurements were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0058] Adhesive D: Main agent (polyester resin, Takelac A-1143, manufactured by Mitsui Chemicals, Inc.) and curing agent (XDI-based isocyanate, Takenate D-110N, manufactured by Mitsui Chemicals, Inc.) in a solid mass ratio of 100:18.5

[0059] (Laminate) Double-sided laminate A double-sided laminate was produced in the same manner as in Example 1 using adhesive D.

[0060] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 1. The evaluation indexes were as described above.

[0061] Furthermore, the adhesive layer and the resin film were visually observed for adhesion after heat treatment for 24 hours at a temperature of 85°C and a relative humidity of 85% in the same manner as in Example 1. The results are shown in Table 1. The evaluation criteria were as described above.

[0062] Comparative Example 2 (adhesive layer) Using the following adhesive E, various measurements were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0063] Adhesive E: Main agent (polyester resin, Toyo-Morton LIS-8420) and curing agent (XDI isocyanate, Mitsui Chemicals Takenate D-110N) in a solid mass ratio of 100:8

[0064] (Laminate) Double-sided laminate A double-sided laminate was produced in the same manner as in Example 1 using adhesive E.

[0065] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 1. The evaluation indexes were as described above.

[0066] Furthermore, the adhesive layer and the resin film were visually observed for adhesion after heat treatment for 24 hours at a temperature of 85°C and a relative humidity of 85% in the same manner as in Example 1. The results are shown in Table 1. The evaluation criteria were as described above.

[0067] [Table 1]

[0068] From Table 1 above, it can be seen that in all Examples, delamination of the decorative sheet hardly occurs after molding or the subsequent heat treatment, and good moldability can be exhibited.

[0069] [Examples 4 to 7] For the double-sided laminate of Example 1, various measurements were carried out in the same manner as in Example 1, except that the thicknesses of the adhesive layers formed on both sides were as shown in Table 2, and a double-sided laminate was also produced.

[0070] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 2. The evaluation indexes were as described above.

[0071] Furthermore, the adhesive layer and the resin film were visually observed for adhesion after heat treatment for 24 hours at a temperature of 85°C and a relative humidity of 85% in the same manner as in Example 1. The results are shown in Table 2. The evaluation criteria were as described above.

[0072] [Table 2]

[0073] From Table 2 above, it can be seen that in all Examples, delamination of the decorative sheet hardly occurs after molding or the subsequent heat treatment, and good moldability can be exhibited.

[0074] [Example 8] For the double-sided laminate of Example 1, various measurements were carried out in the same manner as in Example 1, except that a resin substrate having a glass transition temperature of 130°C and a thickness of 200 μm (Panlite PC-1E51 manufactured by Teijin Limited) was used, and a double-sided laminate was also produced.

[0075] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 3. The evaluation indexes were as described above.

[0076] Furthermore, the adhesiveness between the adhesive layer and the resin film was visually observed after heat treatment at a temperature of 85°C and a relative humidity of 85% for 24 hours in the same manner as in Example 1. The results are shown in Table 3. The evaluation criteria were as described above.

[0077] [Example 9] For the double-sided laminate of Example 1, various measurements were carried out in the same manner as in Example 1, except that a 200 μm thick acrylic resin film with a glass transition temperature of 110°C was used as the resin substrate, and a double-sided laminate was also produced.

[0078] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 3. The evaluation indexes were as described above.

[0079] Furthermore, the adhesiveness between the adhesive layer and the resin film was visually observed after heat treatment at a temperature of 85°C and a relative humidity of 85% for 24 hours in the same manner as in Example 1. The results are shown in Table 3. The evaluation criteria were as described above. [Table 3]

[0080] [Example 10] For the double-sided laminate of Example 1, various measurements were carried out in the same manner as in Example 1, except that an acrylic film (Acryplene HBA007P manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) was used as the resin film, and a double-sided laminate was also produced.

[0081] (Delamination evaluation) The double-sided laminate was subjected to insert molding in the same manner as in Example 1 to produce a molded body. After insert molding, the adhesion between the adhesive layer and the resin film was visually observed. The results are shown in Table 3. The evaluation indexes were as described above.

[0082] Furthermore, the adhesive layer and the resin film were visually observed for adhesion after heat treatment at 85°C x 85% RH x 24 hours, simulating an in-vehicle durability test, in the same manner as in Example 1. The results are shown in Table 4. The evaluation criteria were as described above.

[0083] [Table 4]

Claims

1. An adhesive layer formed on a resin substrate, the adhesive layer having an adhesive strength of 0.4 N / mm or more as measured by the following method (1) and a tensile modulus of elasticity of 0.8 MPa or more as measured by the following method (2). Method (1): Adhesion strength measurement method A polycarbonate sheet having a thickness of 0.2 mm and made of a polycarbonate resin having a Tg of 150 to 160°C was used as the resin substrate, and the adhesive layer having a thickness of 0.01 mm was formed thereon. A polyester film having a thickness of 0.1 mm and made of a polyester resin having a Tg of 70 to 80°C was then bonded to the resin film to prepare a 15 mm wide test piece. The polycarbonate sheet side of the test piece was folded back and set in a tensile tester. The test piece was then held at 140°C for 2 minutes, and the peel strength between the polycarbonate sheet and the polyester film was measured using the tensile tester, and this was taken as the adhesive strength. Method (2): Measurement method of tensile modulus A measurement sheet having a thickness of 0.05 mm is prepared using a single layer of the adhesive alone, and this is cut into a 15 mm wide test piece. The test piece is set in a tensile tester so that the gripping distance is 150 mm, and after holding at 140°C for 2 minutes, the tensile modulus is measured using the tensile tester.

2. The adhesive layer according to claim 1 , wherein the adhesive layer is a cured product of an adhesive containing a polyester resin and a diisocyanate compound.

3. The adhesive layer according to claim 1, wherein the thickness of the adhesive layer is 1 to 30 μm.

4. A laminate having an adhesive layer and a resin film layer in this order on at least one surface side of a resin substrate, wherein the adhesive layer is the adhesive layer according to any one of claims 1 to 3.

5. The laminate according to claim 4, wherein the resin substrate has a glass transition temperature of 120°C or higher.

6. 5. The laminate according to claim 4, wherein the resin film is a polyester resin.

7. 5. The laminate according to claim 4, wherein the ratio (Ta / Tf) of the thickness (Ta) of the adhesive layer to the thickness (Tf) of the resin film layer is 0.005 to 1.

5.

8. A decorative sheet comprising the laminate according to claim 4.

Images