Manufacturing method of laminate

Abstract

To provide a production method of a flexible laminate without warpage, used for a touch sensor and a screen display.SOLUTION: A production method of a laminate for obtaining a laminate of a resin film and a substrate A, includes: a process A of forming a resin film on a supporting material A; a process B of bonding a supporting material B on a face opposite to a side provided with the supporting material A of the resin film to obtain a laminate; a process C of separating the laminate obtained in the process B by a boundary face between the supporting material A and the resin film to obtain the laminate of the resin film and the supporting material B; a process F of shrinking the laminate of the resin film and the supporting material B by 2,000 ppm or more; a process D' of bonding the substrate A onto a face opposite to a side provided with the supporting material B of the laminate after the process F to obtain a laminate; and a process E' of separating the laminate obtained in the process D' by a boundary face between the supporting material B and the resin film to obtain a laminate of the resin film and the substrate A.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a laminate used in flexible touch sensors, screen displays, and the like. [Background technology]

[0002] In recent years, flexible applications for electronic devices such as smartphones and tablets have been studied, and in order to improve flexibility, there is a demand for thinner resin films with touch sensor functions and image display components such as organic light-emitting diode panels, liquid crystal panels, and electronic paper. One known manufacturing method for such devices involves forming a resin film such as polyimide or COP (cycloolefin polymer) on a support material such as glass, forming electrodes for the touch sensor thereon, peeling the resin film at the interface between the glass and the resin film, and then bonding it to a substrate such as a PET film, an OLED panel, a polarizing plate, a color filter, a TFT substrate, or a cover glass, thereby producing a thin, highly flexible electronic device (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-116859 [Patent Document 2] Japanese Patent Application Publication No. 2018-132768 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-34590 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in recent years, there has been an increasing demand for thinner touch sensors and image display components, necessitating the use of thinner resin films and substrates. Conventional methods involve forming a resin film, such as a polyimide or COP (cycloolefin polymer), on a glass substrate, peeling it off the glass substrate, and laminating it on a PET film or similar. However, when the resin film becomes too thin, the stress caused by peeling can cause the resin film itself to tear, and the lack of stiffness makes it difficult to handle.

[0005] One possible solution is to directly form a resin film, such as polyimide or COP (cycloolefin polymer), on the target PET film. However, polyimide films are typically obtained by coating and drying a polyimide dissolved in a solvent on a PET film, then optionally subjecting it to ring closure. However, the volume shrinks due to solvent evaporation and the dehydration reaction accompanying the ring closure, generating shrinkage stress within the polyimide film. This shrinkage stress in the polyimide film can cause warping of the laminate, along with the thin PET film. This is also true for melt-cast lamination, such as polyolefin films. When the molten resin cools and solidifies, volume shrinkage also generates shrinkage stress within the resin film, resulting in warping of the laminate with the PET film.

[0006] Therefore, an object of the present invention is to provide a method for producing a laminate that suppresses warping of the laminate even when a highly shrinkable material is used. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention mainly has the following configuration.

[0008] The present invention is a method for producing a laminate comprising a resin film and a substrate (substrate A) on which the resin film is to be laminated, A step (step A) of forming a resin film on a support material (support material A); A step (step B) of bonding another support material (support material B) to the surface of the resin film opposite to the support material A to obtain a laminate; A step (step C) of peeling the laminate obtained in step B at the interface between the support material A and the resin film to obtain a laminate of the resin film and the support material B; A step (step D) of obtaining a laminate by bonding a substrate A to the surface of the laminate obtained in the step C opposite to the side where the support material B is provided; a step (step E) of peeling the laminate obtained in step D at the interface between the support material B and the resin film to obtain a laminate of the resin film and the substrate A; In this method for producing a laminate, when the elastic modulus of the resin film is Ea and the elastic modulus of the support material B is Eb, Eb / (Ea+Eb) is 0.04 or less. [Effects of the Invention]

[0009] According to the present invention, warping of the laminate can be suppressed to a high degree even when a highly shrinkable material is used. [Brief explanation of the drawings]

[0010] [Figure 1] 1A to 1C are schematic diagrams illustrating a method for manufacturing a laminate according to a first embodiment. [Figure 2] 10A and 10B are schematic diagrams showing an example of a jig for stretching the support material B according to the second embodiment, where (a) is a front view and (b) is a cross-sectional view taken along the line AA'. [Figure 3] FIG. 13 is a diagram illustrating the application pattern of the conductive paste in the touch sensor produced in Example 13. [Figure 4] 13A and 13B are diagrams showing a model of the touch sensor produced in Example 13, where (a) is a top view and (b) is a side view seen from side A. DETAILED DESCRIPTION OF THE INVENTION

[0011] As a result of their investigations, the inventors have come up with the invention of a method for manufacturing a laminate that can suppress warping of the laminate and also has good handling properties, even when a highly shrinkable material is used, by performing a special treatment to relieve shrinkage stress.

[0012] Hereinafter, modes for carrying out the method for producing a laminate according to the present invention (hereinafter referred to as "embodiments") will be described. Note that the drawings are schematic. Furthermore, the present invention is not limited to the embodiments described below.

[0013] [First embodiment] The method for manufacturing the laminate according to this embodiment is A method for producing a laminate comprising: obtaining a laminate of a resin film and a substrate (substrate A) on which the resin film is to be laminated; A step (step A) of forming a resin film on a support material (support material A); A step (step B) of laminating another support material (support material B) to the surface of the resin film opposite to the side on which the support material A is provided to obtain a laminate; A step (step C) of peeling the laminate obtained in step B at the interface between the support material A and the resin film to obtain a laminate of the resin film and the support material B; A step (step D) of obtaining a laminate by bonding a substrate A to the surface of the laminate obtained in the step C opposite to the side where the support material B is provided; a step (step E) of peeling the laminate obtained in step D at the interface between the support material B and the resin film to obtain a laminate of the resin film and the substrate A; When the elastic modulus of the resin film is Ea and the elastic modulus of the support material B is Eb, Eb / (Ea+Eb) is 0.04 or less.

[0014] The method for producing a laminate according to this embodiment is a method for producing a laminate comprising a resin film and a substrate (substrate A) on which the resin film is to be laminated.

[0015] Examples of resin films include polyimide, COP, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), PC (polycarbonate), and acrylic. Among these, polyimide is preferred from the viewpoint of flexibility and optical properties. Transparent polyimide having a yellowness index (YI value) of 0.0 or more and 2.0 or less, preferably 0.0 or more and 1.5 or less, is also preferred. Two or more of these may be laminated, and an electrode, a light-emitting layer, an inorganic thin film, etc. may be formed on the resin film.

[0016] The elastic modulus Ea of the resin film should be such that Eb / (Ea+Eb), which will be described later, is 0.04 or less. 8.5 Pa~10 9.8 It can be done with Pa.

[0017] The elastic modulus Ea of the resin film can be determined from the slope of the stress-strain curve using a tensile tester by the method described in the Examples. It can be determined in the same way even if the resin film is a laminate of two or more layers.

[0018] The thickness of the resin film is preferably 3 to 50 μm. When the thickness of the resin film is 3 μm or more, the strength of the resin film is improved, and it is possible to prevent the resin film from cracking when peeling off the resin film in step C. Furthermore, when the thickness of the resin film is 50 μm or less, high flexibility can be obtained.

[0019] Examples of the substrate A include a PET film, a PP (polypropylene) film, a PE (polyethylene) film, an OLED (organic light emitting diode) panel, a polarizing plate, a color filter, a TFT (thin film transistor) substrate, and a cover glass.

[0020] <Process A> The method for manufacturing a laminate according to this embodiment includes a step of forming a resin film on a support material (support material A). As described above, the resin film attempts to shrink but cannot because it is fixed to support material A, and residual stress occurs in the resin film, and the residual stress remains within the film.

[0021] Examples of methods for forming the resin film include a method in which a varnish is applied to the support material A, the applied varnish is dried, the resulting dried film is exposed to light, and the exposed film is heated.

[0022] When a varnish is applied to the support material A, the varnish contains a resin or a resin precursor and may contain a solvent. The type of solvent is not particularly limited and can be selected appropriately depending on the solubility of the resin used and the application method. One or a mixture of two or more of ester-based solvents, ketone-based solvents, glycol ether-based solvents, aliphatic solvents, alicyclic solvents, aromatic solvents, alcohol-based solvents, and aqueous solvents can be used. Specific examples include N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethyl sulfoxide, γ-butyrolactone, ethyl lactate, 2-dimethylaminoethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, and propylene glycol monomethyl ether acetate.

[0023] Examples of methods for applying the varnish include spin coating using a spinner, spray coating, roll coating, screen printing, and coating using a blade coater, die coater, calendar coater, meniscus coater, or bar coater.

[0024] Methods for drying the applied varnish include, for example, heat drying using an oven, a hot plate, infrared rays, etc., vacuum drying, etc. Heat drying is preferably carried out at a temperature in the range of 50°C to 180°C for 1 minute to several hours.

[0025] The resulting dried film is then photocured by exposure. A mercury lamp, LED, LD, xenon lamp, etc. can be used as the light source for exposure. Thermal curing methods include heating and drying using an oven, inert oven, hot plate, infrared, etc., and vacuum drying.

[0026] The exposed film is then heated, preferably at a temperature in the range of 100 to 300°C.

[0027] When the resin film is formed of two or more layers, the same operation can be repeated to laminate them. Furthermore, the resin film used in the present invention may be a resin film, and a structure made of a material other than resin may be provided on the resin film as long as the effect of the invention is not impaired. When an electrode, a light-emitting layer, an inorganic thin film, etc. are formed on the resin film, they can be formed by sputtering, vapor deposition, ion plating, screen printing, spin coating, slit die coating, gravure printing, flexographic printing, etc.

[0028] Support material A can be made of glass, quartz, alumina, zirconia, SUS, polyimide, acrylic, or the like. When laser is used to peel support material A from the resin film in step C, which will be described later, glass is preferred because of its high light transmittance and heat resistance. A release layer may also be provided on the surface of support material A. By providing a release layer, the adhesive strength between support material A and the resin film is reduced, allowing for easy peeling with little force in step C.

[0029] <Process B> The method for producing a laminate according to this embodiment includes a step of laminating another support material (support material B) to the surface of the resin film opposite to the side on which support material A is provided, to obtain a laminate.

[0030] Examples of the support material B include Intelimer (registered trademark) tapes CS2350NA4, CS2325NA4, and CS2325NA3 (all manufactured by Nitta Corporation).

[0031] The elastic modulus Eb of the support material B should be such that Eb / (Ea+Eb), which will be described later, is 0.04 or less. However, in consideration of the elastic modulus of a resin film that can usually be used, it is preferable that it is 10 6.0 Pa~10 8.5 The elastic modulus Eb of support material B is 106.0 When the elastic modulus Eb of the support material B is 10 Pa or more, the resin film can be supported without being deformed. 8.5 By setting the elastic modulus Eb of the support material B to 10 Pa or less, when a laminate of the resin film and the support material B is obtained in step C, the support material B shrinks together with the resin film, and the residual stress of the resin film can be further reduced. 6.8 Pa or less.

[0032] The thickness of the support material B is preferably 15 μm to 500 μm. When the thickness of the support material B is 15 μm or more, it becomes easy to handle. On the other hand, when the thickness of the support material B is 500 μm or less, the resin film tends to shrink together with the support material B in step C, and the residual stress of the resin film can be further reduced. The thickness of the support material B is more preferably 30 μm or less.

[0033] In the method for manufacturing a laminate according to this embodiment, when the elastic modulus of the resin film is Ea and the elastic modulus of the support material B is Eb, Eb / (Ea+Eb) is 0.04 or less. If Eb / (Ea+Eb) is greater than 0.04, the laminate of the resin film and the support material B does not shrink sufficiently in step C described below, and the residual stress in the resin film increases. As a result, warping occurs after forming the laminate of the resin film and the substrate A in step E.

[0034] <Process C> The method for manufacturing a laminate according to this embodiment includes a step of peeling the interface between support material A and the resin film from the laminate obtained in step B to obtain a laminate of the resin film and support material B. In this step, the resin film separates from support material A and shrinks together with support material B due to residual stress. If the shrinkage is insufficient, stress remains within the resin film.

[0035] The peeling method may be a mechanical peeling method or a method of irradiating the interface between the support material A and the resin film with a laser from the back surface of the support material A.

[0036] <Process D> The method for producing a laminate according to this embodiment includes a step of laminating a substrate A to the surface of the laminate obtained in step C opposite to the side on which the support material B is provided, to obtain a laminate.

[0037] The laminate obtained in step C and substrate A can be bonded together using a bonding device by fixing the surfaces opposite to those to be bonded on an adsorption stage, and then releasing the fixation after joining the surfaces to be bonded. When bonding, an easily deformable member such as a screen mesh is used as the adsorption stage, and the bonding is performed while rubbing with a roller or blade, etc., to prevent the occurrence of bubbles and wrinkles. An example of a bonding device is the manual sheet-fed bonding machine SE650n (manufactured by Clime Products).

[0038] <Process E> The method for producing a laminate according to this embodiment includes a step of obtaining a laminate of a resin film and a substrate A by peeling the support material B and the resin film from the laminate obtained in step D at the interface between them. In this step, if the residual stress of the resin film is large, warping occurs in the laminate of the resin film and the substrate A, but if the residual stress of the resin film is small, warping can be suppressed.

[0039] [Second embodiment] The method for producing a laminate according to the present embodiment is a method for producing a laminate of a resin film and a substrate (substrate A) on which the resin film is to be laminated, and includes the steps of: A step (step A) of forming a resin film on a support material (support material A); A step (step B) of laminating another support material (support material B) to the surface of the resin film opposite to the side on which the support material A is provided to obtain a laminate; A step (step C) of peeling the support material A and the resin film from the laminate obtained in step B at the interface between them to obtain a laminate of the resin film and the support material B; A process (process F) of shrinking the laminate of the resin film and the support material B by 2000 ppm or more; After the step F, a step (step D') of laminating a substrate A to the surface of the laminate obtained in the step C opposite to the side on which the support material B is provided to obtain a laminate; The method includes a step (step E') of peeling the support material B and the resin film from the laminate obtained in step D' at the interface between them to obtain a laminate of the resin film and the substrate A.

[0040] The method for producing a laminate according to this embodiment includes, after step C, a step (step F) of shrinking the laminate of the resin film and support material B by 2000 ppm or more. This step relieves residual stress in the resin film. If the amount of shrinkage of the laminate of the resin film and support material B is less than 2000 ppm, warping is likely to occur when a laminate of the resin film and substrate A is obtained in step E. The amount of shrinkage of the laminate of the resin film and support material B is more preferably 4000 ppm or more.

[0041] Methods for shrinking a laminate of a resin film and support material B include lowering the temperature of the laminate of a resin film and support material B, or laminating a laminate of support material A and a resin film to support material B that has been stretched in advance, then peeling support material A off, and then shrinking support material B to which the resin film has been laminated. Note that the significance of stretching support material B here is that it expands its surface area by applying heat or external force, and then restores its original shape when the heat or external force is removed, thereby removing residual stress in the resin film that is laminated.

[0042] When lowering the temperature of the laminate of the resin film and support material B, the laminate of the resin film and support material B can be made 2000 ppm or more by adjusting the temperature to be lowered depending on the thermal expansion coefficient of support material B. Examples of support material B include urethane gel, silicone gel, PMMA (polymethyl methacrylate), and magnesium alloy AZ91. Furthermore, a separate adhesive layer may be provided on support material B. This allows even a non-adhesive material to be used as support material B.

[0043] In step B, when the temperatures of support material A and the resin film and support material B are kept constant and then the laminate of the resin film and support material B is shrunk in step F, the thermal expansion coefficient of support material B is preferably 20 ppm / K to 230 ppm / K. By making the thermal expansion coefficient of support material B 20 ppm / K or more, dimensional changes due to thermal expansion can be easily increased even with small temperature changes. On the other hand, by making the thermal expansion coefficient of support material B 230 ppm / K or less, variations in dimensional changes due to temperature variations in support material B can be reduced.

[0044] The temperature to which the support material B is cooled is preferably 10°C or higher and 150°C or lower. By setting the temperature to 10°C or higher, a material with a small thermal expansion coefficient can be used as the support material B. The temperature is more preferably 30°C or higher. Furthermore, by setting the temperature to 150°C or lower, thermal deterioration of the support material B can be suppressed. Furthermore, the temperature of the support material B can be increased and decreased in a short time. The temperature is more preferably 100°C or lower.

[0045] In the case where a laminate of support material A and a resin film is laminated to support material B that has been stretched in advance, support material A is peeled off, and then support material B with the laminated resin film is shrunk to shrink the laminate of the resin film and support material B by 2000 ppm or more, an example of a method for pre-stretching support material B and shrinking it after lamination is to stretch support material B using a jig and then release the stretching after lamination. The stretching amount in this case is preferably 0.2 to 1.5%. By setting the stretching amount to 0.2% or more, warping can be further suppressed when a laminate of resin film and substrate A is obtained in step E. On the other hand, by setting the stretching amount to 1.5% or less, wrinkles and cracks can be prevented from occurring in the resin film during shrinkage in step F.

[0046] As a jig for stretching the support material B, for example, the one shown in Figure 2 can be used. This jig has the function of moving the clamp 23 from the center of the guide 22 outward by turning the screw 21 while fixing the guide 22. The rotation of the clamp 23 is prevented by placing a steel ball moistened with lubricating oil between the screw 21 and the clamp 23. By fixing the support material B24 with the clamp 23, the support material B24 can be stretched from the center outward. It is preferable to stretch the support material B24 evenly in all directions.

[0047] The support material B may be a urethane gel sheet or the like.

[0048] <Process D', Process E'> The same methods as those described in the sections on steps D and E can be applied to the laminate after step F. Then, a laminate of the resin film and the substrate A can be obtained.

[0049] In the present invention, a functional structure such as a conductive pattern can be provided on the resin film obtained in step A. The resin film provided with the conductive pattern can be suitably used as a member for a touch sensor. Examples of the conductive pattern include a transparent conductive pattern made of indium tin oxide (ITO), and an opaque conductive pattern made by applying a conductive paste in which silver particles are dispersed in a resin. A conductive paste in which silver particles are dispersed can be made photosensitive to form a variety of patterns, and is advantageous in terms of the flexibility of the conductive pattern itself and its adhesion to the resin film. The line width of the conductive pattern is preferably 1 μm to 9 μm, and more preferably 1 μm to 5 μm. [Example]

[0050] EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0051] <Measurement of elastic modulus> Using a method similar to that described in the Examples, a resin film consisting of two layers, a 7 μm thick polyimide film and a 3 μm thick protective film, with a total thickness of 10 μm was formed on an alkali-free glass substrate.Then, using a single-edged razor, strips of 50.4 mm long x 10.1 mm wide were cut into the resin film, and the cut was peeled off from the substrate to obtain a resin film test piece of approximately 50 mm long x 10 mm wide x 10 μm thick.

[0052] The elastic modulus was measured by first determining the width of the test piece with a vernier caliper and the thickness with a micrometer. The resulting rectangular test piece was then tensile-tested at 50 mm / min using an AG-5kNI thermostatic tensile tester (Shimadzu Corporation) to a test length of 30 mm by fixing approximately 10 mm above and below the test piece with a chuck. The elastic modulus was calculated from the slope of the stress-strain curve over an elongation range of 0 to 2%. The test was performed 10 times, and the arithmetic average value was calculated.

[0053] For the support material B, strip-shaped test pieces measuring approximately 50 mm in length and approximately 10 mm in width were prepared by cutting them out, and the elastic modulus was measured in the same manner.

[0054] <Warp evaluation> The laminate of the PET film and the resin film obtained in each Example and Comparative Example was placed on a stage with the PET film side facing downward, and the maximum height from the stage was measured with a vernier caliper. If the laminate was convex downward, the amount of warping was recorded as positive, and if the laminate was convex upward, the amount of warping was recorded as negative. Measurements were made on 10 sheets, and the arithmetic average was calculated.

[0055] <Measurement of the resin ratio in the conductive pattern> The laminate provided with the conductive pattern was cut using a single-edged razor so as not to crush the cross section of the conductive pattern, and then the cross section was smoothed using an ion milling device IB-9010CP (manufactured by JEOL Ltd.). The cross section was then observed using a field emission analytical scanning electron microscope JSM-7610F (manufactured by JEOL Ltd.). Observation was performed under conditions that provided contrast that allowed the metal, resin, and voids to be distinguished, and the areas of the metal and resin in the cross section were calculated and expressed as the volume fraction in percentage. The volume fraction was calculated by averaging 20 points each on the first and second conductive patterns, a total of 40 points.

[0056] <Touch sensor evaluation> The laminate provided with the conductive pattern was bent 180 degrees with a curvature radius of 3 mm so that the conductive pattern was on the inside, returned to its original position, and then bent 180 degrees with a curvature radius of 3 mm so that the conductive pattern was on the outside, and returned to its original position. This set of operations was repeated 50,000 times, and then the following conductivity evaluation and appearance inspection were carried out.

[0057] Conductivity evaluation The resistance values ​​were measured at 40 locations in total (20 locations each on the first and second layers of the conductive patterns) by connecting both ends with a resistance meter (RM3544; manufactured by HIOKI) and calculating the average, maximum, and minimum values. Values ​​above the resistance meter's measurement limit of 3.5 MΩ were deemed unmeasurable and excluded from the calculation of the average value.

[0058] Visual inspection If the first and second conductive patterns had no cracks, peeling, or disconnections, they were judged as passing, and if not, they were judged as failing.

[0059] The materials used in each of the examples and comparative examples are as follows. [solvent] Dimethylethanolamine (DMEA, manufactured by Tokyo Chemical Industry Co., Ltd.) N-methylpyrrolidone (NMP, manufactured by Tokyo Chemical Industry Co., Ltd.) Cellosolve acetate (CA, manufactured by Tokyo Chemical Industry Co., Ltd.) [Epoxy resin] jeR828 (Mitsubishi Chemical Corporation) [Photopolymerization initiator] IRGACURE 369 (manufactured by Ciba Japan Co., Ltd.) [Silica dispersion] ·DMAC-ST (manufactured by Nissan Chemical).

[0060] (Synthesis Example 1) Under a nitrogen stream, 100 g of NMP was added to a 300 ml separable flask and heated to 55°C with stirring. 2.47 g of 1,4-bis(aminomethyl)cyclohexane and 4.31 g of 3,3'-diaminodiphenyl sulfone were added and dissolved in NMP. 9.77 g of 4,4'-oxydiphthalic anhydride (ODPA) and 0.687 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) were added to this solution, and the solution was stirred at 55°C for 90 minutes to carry out a polymerization reaction. 3 g of silica dispersion DMAC-ST was added to the resulting solution and stirred at room temperature for 60 minutes to obtain polyamic acid solution (A-1).

[0061] (Synthesis Example 2) An acrylic copolymer of ethylenediamine (EA) / 2-ethylhexyl methacrylate (2-EHMA) / styrene (St) / acrylic acid (AA) (copolymerization ratio (parts by mass): 20 / 40 / 20 / 15) with 5 parts by mass of glycidyl methacrylate (GMA) added and reacted. A reaction vessel under a nitrogen atmosphere was charged with 150 g of DMEA and heated to 80 °C using an oil bath. A mixture consisting of 20 g of EA, 40 g of 2-EHMA, 20 g of St, 15 g of AA, 0.8 g of 2,2'-azobisisobutyronitrile, and 10 g of DMEA was added dropwise over 1 hour. After the dropwise addition was completed, the polymerization reaction was continued for an additional 6 hours. 1 g of hydroquinone monomethyl ether was then added to terminate the polymerization reaction. Subsequently, a mixture consisting of 5 g of GMA, 1 g of triethylbenzylammonium chloride, and 10 g of DMEA was added dropwise over 0.5 hours. After the dropwise addition was completed, the addition reaction was continued for an additional 2 hours. The resulting reaction solution was purified with methanol to remove unreacted impurities, and then vacuum dried for 24 hours to obtain acrylic copolymer (B-1). The acid value of the resulting acrylic copolymer (B-1) was 103 mg KOH / g.

[0062] (Synthesis Example 3) In a 100 mL clean bottle, 10.0 g of the acrylic copolymer (B-1), 3.0 g of Light Acrylate BP-4EA, 2.0 g of the epoxy resin jeR828, 0.6 g of IRGACURE 369, and 60.0 g of DMEA were placed and mixed using an "Awatori Rentaro" (ARE-310; manufactured by Thinky Corporation) to obtain 75.6 g of an overcoat solution (C-1).

[0063] (Synthesis Example 4) In a 100 mL clean bottle, 10.0 g of acrylic copolymer (B-1), 2.0 g of Light Acrylate BP-4EA, 0.60 g of photopolymerization initiator IRGACURE369 (manufactured by Ciba Japan Co., Ltd.), and 8.0 g of CA were placed and mixed using a "Thinky Mixer" (trade name, ARE-310, manufactured by Thinky Corporation) to obtain 20.6 g of photosensitive resin solution (total solids content 61.2 mass%). 10.0 g of the resulting photosensitive resin solution was mixed with 22.0 g of Ag particles with an average particle size of 0.2 μm and kneaded using a three-roller "EXAKT M-50" (trade name, manufactured by EXAKT Co., Ltd.) to obtain 32.0 g of conductive paste (D-1).

[0064] ( Reference example 1 ) A polyamic acid solution (A-1) was applied to the entire surface of a 0.7 mm thick, 150 mm square alkali-free glass substrate AN100 (manufactured by Asahi Glass Co., Ltd.) and dried in a hot air oven at 90°C for 15 minutes. This was then thermally cured in a hot air oven at 260°C for 60 minutes to form a polyimide film with a thickness of 7 μm. An overcoat solution (C-1) was applied to the entire surface of this polyimide film and dried in a hot air oven at 90°C for 8 minutes. An exposure device PEM-6M (manufactured by Union Optical Co., Ltd.) was used to apply an exposure dose of 200 mJ / cm. 2 After full-line exposure at 365 nm wavelength, the film was thermally cured in a hot air oven at 230°C for 60 minutes, forming a 3 μm thick protective film, yielding a 10 μm thick resin film. A 150 mm square Intelimer Tape CS2350NA4 (manufactured by Nitta Corporation) with a total thickness of 50 μm was then laminated onto the resin film, and the resin film and Intelimer Tape were then peeled off from the glass substrate. A 50 μm thick self-adhesive PET film was then laminated to the resin film side (the side separated from the glass substrate) using a lamination device SE650n (manufactured by Clime Products). The Intelimer Tape was then peeled off, yielding a laminate in which a 50 μm PET film was laminated to a 10 μm thick resin film.

[0065] ( Reference example 2 ) Except for using Intellimer Tape CS2325NA4 (manufactured by Nitta Corporation) with a total thickness of 25 μm instead of Intellimer Tape CS2350NA4 with a total thickness of 50 μm. Reference example 1 was carried out in the same manner.

[0066] ( Reference example 3 ) Except for using Intellimer Tape CS2350NA3 instead of Intellimer Tape CS2350NA4. Reference example 1 was carried out in the same manner.

[0067] ( Comparative example 1 ) Except for using PET instead of Intellimer tape CS2325NA4 Reference example 1 was carried out in the same manner.

[0068] Reference examples 1~3 , Comparative example 1 The evaluation results are shown in Table 1.

[0069] Example 4 A polyamic acid solution (A-1) was applied to the entire surface of a 0.7 mm thick, 150 mm square alkali-free glass substrate AN100 (manufactured by Asahi Glass Co., Ltd.) and dried at 90°C for 15 minutes in a hot air oven. This was then thermally cured at 260°C for 60 minutes in a hot air oven to form a polyimide film with a thickness of 7 μm. An overcoat solution (C-1) was then applied to the entire surface of this polyimide film and dried at 90°C for 8 minutes in a hot air oven. An exposure device PEM-6M (manufactured by Union Optical Co., Ltd.) was then used to apply an exposure dose of 200 mJ / cm. 2 After full-line exposure at 365 nm wavelength, the resin film was thermally cured in a hot air oven at 230°C for 60 minutes, forming a 3 μm-thick protective film, yielding a resin film with a total thickness of 10 μm. The glass substrate and resin film were then held at 100°C, and a 5 mm-thick self-adhesive urethane gel sheet (thermal expansion coefficient 93 ppm / K) preheated to 100°C was laminated onto the resin film. While still held at 100°C, the urethane gel sheet and resin film were separated from the interface between the glass substrate and the resin film, and the urethane gel sheet and resin film were cooled to 25°C. A 50 μm-thick self-adhesive PET film was laminated to the resin film side (the side separated from the glass substrate) of the separated product using a lamination device SE650n (manufactured by Clime Products). The urethane gel sheet was peeled off, yielding a laminate consisting of a 50 μm-thick PET film laminated to a 10 μm-thick resin film.

[0070] Example 5 The same procedure as in Example 4 was carried out except that the temperature before lamination was changed from 100°C to 70°C.

[0071] Example 6 The same procedure as in Example 4 was carried out except that the temperature before lamination was changed from 100°C to 120°C.

[0072] Example 7 The same procedure as in Example 4 was carried out except that a 5 mm thick silicone gel sheet (thermal expansion coefficient 204 ppm / K) was used instead of the urethane gel sheet and the temperature before lamination was changed from 100°C to 60°C.

[0073] Example 8 The same procedure as in Example 4 was carried out, except that a 0.5 mm thick PMMA (thermal expansion coefficient 50 ppm / K) was used instead of the urethane gel sheet and the temperature before lamination was changed from 100°C to 115°C.

[0074] Example 9 The same procedure as in Example 4 was carried out, except that a 0.3 mm thick magnesium alloy AZ91 plate (thermal expansion coefficient 28 ppm / K) was used instead of the urethane gel sheet, and the temperature before bonding was set to 100°C to 150°C and the temperature after bonding was set to 25°C to 0°C.

[0075] Example 10 The same procedure as in Example 4 was carried out except that a 5 mm thick silicone gel sheet was used instead of the urethane gel sheet and the temperature before lamination was changed from 100°C to 35°C.

[0076] (Comparative Example 2) The same procedure as in Example 4 was carried out except that the temperature before lamination was changed from 100°C to 25°C.

[0077] (Comparative Example 3) The same procedure as in Example 4 was carried out except that a 5 mm thick silicone gel sheet was used instead of the urethane gel sheet and the temperature before lamination was changed from 100°C to 30°C.

[0078] Table 2 shows the evaluation results of Examples 4 to 10 and Comparative Examples 2 and 3.

[0079] Example 11 A polyamic acid solution (A-1) was applied to the entire surface of a 0.7 mm thick, 150 mm square alkali-free glass substrate AN100 (manufactured by Asahi Glass Co., Ltd.) and dried in a hot air oven at 90°C for 15 minutes. This was then thermally cured in a hot air oven at 260°C for 60 minutes to form a polyimide film with a thickness of 7 μm. An overcoat solution (C-1) was applied to the entire surface of this polyimide film and dried in a hot air oven at 90°C for 8 minutes. An exposure device PEM-6M (manufactured by Union Optical Co., Ltd.) was used to apply an exposure dose of 200 mJ / cm. 2 After full-line exposure at 365 nm wavelength, the sheet was thermally cured in a hot air oven at 230°C for 60 minutes, forming a 3 μm-thick protective film, yielding a resin film with a total thickness of 10 μm. Using the jig shown in Figure 2, the urethane gel sheet was stretched evenly in all directions along its surface by 0.69%. The urethane gel sheet in the 0.69% stretched state was then bonded onto the resin film. The urethane gel sheet and resin film were then peeled off from the interface between the glass substrate and the resin film, and the urethane gel sheet was released from the stretch, causing the urethane gel sheet and resin film to shrink. A 50 μm-thick self-adhesive PET film was bonded to the resin film side of this peeled-off product (the side separated from the glass substrate). The urethane gel sheet was then peeled off, yielding a laminate consisting of a 50 μm-thick PET film bonded to a 10 μm-thick resin film.

[0080] Example 12 The same procedure as in Example 11 was carried out, except that the stretching amount of the urethane gel sheet was 0.89%.

[0081] Comparative Example 4 The same procedure as in Example 11 was carried out except that the stretch amount of the urethane gel sheet was 0.15%.

[0082] The evaluation results of Examples 11 and 12 and Comparative Example 4 are shown in Table 3.

[0083] ( Reference example 4 ) A polyamic acid solution (A-1) was applied to the entire surface of a 0.7 mm thick, 150 mm square alkali-free glass substrate AN100 (manufactured by Asahi Glass Co., Ltd.) and dried in a hot air oven at 90°C for 15 minutes. This was followed by thermal curing in a hot air oven at 260°C for 60 minutes to form a 7 μm thick polyimide film. A conductive paste (D-1) was applied to the entire surface of the polyimide film using a screen printer LS-150 (manufactured by Newlong Precision Industry Co., Ltd.) and dried in a drying oven at 100°C for 10 minutes to obtain a 1.0 μm thick coating film. A photomask with 20 patterns, each consisting of a 3 μm wide, 0.5 mm diagonal diamond continuum and 1.5 mm square transparent portions at both ends, spaced 4 mm apart, was placed at the center of the substrate, and an exposure dose of 200 mJ / cm was used with an exposure system PEM-6M (manufactured by Union Optical Co., Ltd.). 2 After full-line exposure at 365 nm wavelength, the substrate was immersed in a 0.1% by mass TMAH solution for 30 seconds for development, and then rinsed with ultrapure water to obtain a conductive pattern precursor. This was then thermally cured in a hot air oven at 230°C for 60 minutes to form a first-layer conductive pattern with a line width of 4.0 μm. An overcoat solution (C-1) was applied to the conductive pattern over an area of ​​80 mm x 85 mm, covering only the grid-like portion of the conductive pattern, and the pattern was dried in a hot air oven at 90°C for 8 minutes. An exposure dose of 200 mJ / cm was used using a PEM-6M exposure system (manufactured by Union Optical Co., Ltd.). 2 After full-line exposure at 1000 kJ / cm² (equivalent to a wavelength of 365 nm), the substrate was thermally cured in a hot air oven at 230°C for 60 minutes to form a 3 μm-thick first-layer protective film. A second-layer conductive pattern was formed on the first-layer protective film in the same manner as the first-layer conductive pattern, so that it was perpendicular to the first-layer conductive pattern. An overcoat solution (C-1) was applied to an area of ​​80 mm x 80 mm on top of the second-layer conductive pattern, covering only the grid-like portion of the conductive pattern, and the substrate was dried in a hot air oven at 90°C for 8 minutes. An exposure dose of 200 mJ / cm² was applied using a PEM-6M exposure system (manufactured by Union Optical Co., Ltd.). 2After full-line exposure at 365 nm wavelength, the substrate was thermally cured in a hot air oven at 210°C for 60 minutes to form a 2 μm-thick second protective film, resulting in the touch sensor shown in Figure 4. Next, a 150 mm square Intellimer tape CS2350NA4 (manufactured by Nitta Corporation) with a total thickness of 50 μm was laminated onto the touch sensor, and the resin film and Intellimer tape were then peeled off from the glass substrate. A 50 μm-thick PET film was then laminated to the resin film side of the peeled product (the side separated from the glass substrate) using a lamination device SE650n (manufactured by Clime Products). The Intellimer tape was then peeled off to obtain a laminate in which the 50 μm-thick PET film was laminated to the touch sensor.

[0084] Reference example 4 The evaluation results are shown in Tables 4 and 5.

[0085] [Table 1]

[0086] [Table 2]

[0087] [Table 3]

[0088] [Table 4]

[0089] [Table 5] [Explanation of symbols]

[0090] 11 Support material A 12 Resin film 13 Support material B 14 Base material A 21 screws 22 Guide 23 Clamp 24 Support material B 31 Light-transmitting portion of photomask 41 Polyimide film 42 First layer conductive pattern 43 First protective layer 44 Second layer conductive pattern 45 Second layer of protective film

Claims

1. A method for producing a laminate comprising: obtaining a laminate of a resin film and a substrate (substrate A) on which the resin film is to be laminated; A step (step A) of forming a resin film on a support material (support material A); a step (step B) of laminating another support material (support material B) to the surface of the resin film opposite to the surface on which the support material A is provided to obtain a laminate; A step (step C) of peeling the laminate obtained in step B at the interface between the support material A and the resin film to obtain a laminate of the resin film and the support material B; a step (step F) of shrinking the laminate of the resin film and the support material B by 2000 ppm or more; a step (step D') of laminating a substrate A to the surface of the laminate opposite to the surface on which the support material B is provided after the step F to obtain a laminate; A method for producing a laminate, comprising a step (step E') of peeling the laminate obtained in step D' at the interface between the support material B and the resin film to obtain a laminate of the resin film and the substrate A.

2. In the step F, the method for shrinking the laminate of the resin film and the support material B is The method for producing a laminate according to claim 1, wherein the temperature of the laminate of the resin film and the support material B is lowered.

3. In the step F, the method for shrinking the laminate of the resin film and the support material B is 2. A method for producing a laminate according to claim 1, which comprises laminating a laminate of support material A and a resin film to support material B that has been stretched in advance, then peeling off support material A, and then shrinking support material B to which the resin film has been laminated.

4. The method for producing a laminate according to claim 2, wherein the method for lowering the temperature of the laminate is to lower the temperature of the laminate by 20 to 150°C.

5. 5. The method for producing a laminate according to claim 1, wherein the resin film is a laminate of two or more layers having one or more layers made of transparent polyimide, and the resin film has an opaque conductive pattern having a line width of 1 μm to 9 μm.

6. 6. The method for producing a laminate according to claim 5, wherein the opaque conductive pattern is made of a mixture of metal and resin, and the proportion of resin in the opaque conductive pattern is 30 to 80% by volume.

7. A method for producing a member for a touch sensor, using a laminate obtained by the method for producing a laminate according to claim 5 or 6 as a member.

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