JP7798129B2 - Manufacturing method of laminate - Google Patents

Description

The present invention relates to a method for manufacturing laminates used in flexible touch sensors, screen displays, etc.

In recent years, flexible applications for electronic devices such as smartphones and tablets have been explored. To enhance flexibility, there is a demand for thinner resin films with touch sensor functionality, as well as image display components such as organic light-emitting diode panels, liquid crystal panels, and electronic paper. One known manufacturing method 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 on top of that, peeling it off at the interface between the glass and the resin film, and then bonding it to a substrate such as a PET film, OLED panel, polarizing plate, color filter, TFT substrate, or cover glass, to produce a thin, highly flexible electronic device (Patent Documents 1 to 3).

JP 2018-116859 A Japanese Patent Application Laid-Open No. 2018-132768 JP 2014-34590 A

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 polyimide or COP (cycloolefin polymer) on a glass substrate, peeling it off the glass substrate, and laminating it on a PET film or similar, but these methods have the drawback of causing the resin film to tear due to stress during peeling when the resin film becomes too thin, or making it difficult to handle due to its lack of stiffness.

One possible solution is to form a resin film such as polyimide or COP (cycloolefin polymer) directly on the desired PET film. However, polyimide film is typically obtained by coating and drying polyimide dissolved in a solvent on a PET film, then subjecting it to ring closure as needed. However, the volume shrinks due to the evaporation of the solvent 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 lamination using melt-casting, such as with polyolefin films. The volume shrinkage that occurs when the molten resin cools and solidifies generates shrinkage stress within the resin film, resulting in warping of the laminate with the PET film.

The present invention therefore aims to provide a method for manufacturing a laminate that suppresses warping of the laminate, even when a highly shrinkable material is used.

To solve the above problems, the present invention mainly has the following configuration.

The present invention 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 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 laminating a substrate A to the surface of the laminate obtained in the step C opposite to the surface on which the support material B is provided, to obtain a laminate;
a step (step E) of peeling the laminate obtained in the 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.

According to the present invention, warping of the laminate can be suppressed to a high degree even when a highly shrinkable material is used.

1A to 1C are schematic diagrams illustrating a method for manufacturing a laminate according to a first embodiment. 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 A-A'. FIG. 13 is a diagram illustrating the application pattern of the conductive paste in the touch sensor produced in Example 13. 13A and 13B are diagrams showing a model of the touch sensor produced in Example 13, in which FIG. 13A is a top view and FIG. 13B is a side view seen from side A.

After extensive research, the inventors have come up with a method for manufacturing a laminate that, by performing a special treatment to alleviate shrinkage stress, can suppress warping of the laminate, even when a highly shrinkable material is used, while also providing good handling properties.

The following describes a mode for carrying out the method for manufacturing a laminate according to the present invention (hereinafter referred to as "embodiment"). Note that the drawings are schematic. Furthermore, the present invention is not limited to the embodiment described below.

[First embodiment]
The method for producing a laminate according to the present embodiment is a method for producing a laminate including a resin film and a substrate (substrate A) on which the resin film is to be laminated, and
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 D) of laminating a substrate A to the surface of the laminate obtained in the step C opposite to the surface on which the support material B is provided, to obtain a laminate;
a step (step E) of peeling the laminate obtained in the 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.

The method for manufacturing a laminate according to this embodiment is a method for manufacturing a laminate that obtains a laminate of a resin film and a substrate (substrate A) onto which the resin film is intended to be laminated.

Examples of resin films include polyimide, COP, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), PC (polycarbonate), and acrylic. Among these, polyimide is preferred from the standpoint of flexibility and optical properties. Transparent polyimide with a yellowness index (YI value) of 0.0 to 2.0, preferably 0.0 to 1.5, is also preferred. Two or more of these may be laminated, and electrodes, light-emitting layers, inorganic thin films, etc. may be formed on the resin film.

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, but in view of the elastic modulus of a resin film that can normally be taken, it can be 10 ^8.5 Pa to 10 ^9.8 Pa.

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

The thickness of the resin film is preferably 3 to 50 μm. A resin film thickness of 3 μm or more improves the strength of the resin film, preventing cracks from occurring in the resin film when it is peeled off in step C. Furthermore, a resin film thickness of 50 μm or less can achieve high flexibility.

Examples of substrate A include PET film, PP (polypropylene) film, PE (polyethylene) film, OLED (organic light emitting diode) panels, polarizing plates, color filters, TFT (thin film transistor) substrates, and cover glass.

<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.

One example of a method for forming a resin film is to apply a varnish to support material A, dry the applied varnish, expose the resulting dried film to light, and then heat the exposed film.

When applying a varnish to support material A, the varnish contains a resin or resin precursor and may also contain a solvent. There are no particular limitations on the type of solvent, and it 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 the following solvents can be used: ester-based solvents, ketone-based solvents, glycol ether-based solvents, aliphatic-based solvents, alicyclic-based solvents, aromatic-based solvents, alcohol-based solvents, and water-based solvents. 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.

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

Methods for drying the applied varnish include, for example, heat drying using an oven, hot plate, infrared rays, etc., and vacuum drying. Heat drying is preferably carried out at a temperature ranging from 50°C to 180°C for one minute to several hours.

The resulting dried film is then photocured by exposure. When performing exposure, a mercury lamp, LED, LD, xenon lamp, etc. can be used as a light source. Thermal curing methods include heat drying using an oven, inert oven, hot plate, infrared rays, etc., and vacuum drying.

Furthermore, the exposed film is heated. The heating temperature is preferably in the range of 100 to 300°C.

When the resin film is formed from two or more layers, the same operation can be repeated to stack the layers. Furthermore, the resin film used in the present invention only needs to be a resin film, and structures made of materials other than resin may be provided on the resin film as long as the effects of the invention are not impaired. When forming electrodes, light-emitting layers, inorganic thin films, etc. 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.

Support material A can be made of glass, quartz, alumina, zirconia, SUS, polyimide, acrylic, etc. When using a laser to peel support material A from the resin film in step C, which will be described later, glass is preferred, as it has high light transmittance and heat resistance. A release layer may also be provided on the surface of support material A. The provision of a release layer reduces the adhesion between support material A and the resin film, allowing for easy peeling with little force in step C.

<Process B>
The method for manufacturing 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.

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

The elastic modulus Eb of support material B should be such that Eb/(Ea+Eb), described below, is 0.04 or less, but can be 10 ^6.0 Pa to 10 ^8.5 Pa in consideration of the elastic modulus of a resin film that can normally be obtained. When the elastic modulus Eb of support material B is 10 ^6.0 Pa or more, the resin film can be supported without being deformed. On the other hand, when the elastic modulus Eb of support material B is 10 ^8.5 Pa or less, when a laminate of the resin film and support material B is obtained in step C, the support material B will shrink together with the resin film, thereby further reducing the residual stress in the resin film. The elastic modulus Eb of support material B is more preferably 10 ^6.8 Pa or less.

The thickness of support material B is preferably 15 μm to 500 μm. Having a thickness of 15 μm or more makes support material B easier to handle. On the other hand, having a thickness of 500 μm or less makes it easier for the resin film to shrink together with support material B in step C, further reducing the residual stress in the resin film. The thickness of support material B is more preferably 30 μm or less.

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 support material B will not shrink sufficiently in step C, which will be described later, and the residual stress in the resin film will increase. As a result, warping will occur after the laminate of the resin film and substrate A is formed in step E.

<Process C>
The method for manufacturing a laminate according to this embodiment includes a step 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 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.

Removal methods include mechanical peeling and irradiating the interface between support material A and the resin film with a laser from the backside of support material A.

<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.

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 can be used as the adsorption stage, and the materials can be bonded while rubbing with a roller or blade to prevent bubbles and wrinkles from forming. Examples of bonding devices include the manual sheet-fed bonding machine SE650n (manufactured by Climb Products).

<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.

[Second embodiment]
The method for producing a laminate according to the present embodiment is a method for producing a laminate including 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 surface 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 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;
After the step F, a step (step D') is performed in which a substrate A is bonded to the surface of the laminate obtained in the step C opposite to the surface 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.

The method for manufacturing 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.

Methods for shrinking a laminate of resin film and support material B include lowering the temperature of the laminate of resin film and support material B, or laminating a laminate of support material A and resin film to pre-stretched support material B, then peeling support material A off, and then shrinking support material B with the laminated resin film. 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 shape when the heat or external force is removed, thereby removing any residual stress in the laminated resin film.

When lowering the temperature of the laminate of the resin film and support material B, the temperature can be adjusted according to the thermal expansion coefficient of support material B to make the laminate of the resin film and support material B 2000 ppm or more. Examples of support material B include urethane gel, silicone gel, PMMA (polymethyl methacrylate), and magnesium alloy AZ91. Support material B may also be provided with a separate adhesive layer. This allows even non-adhesive materials to be used as support material B.

In step B, support material A and the resin film are bonded together while maintaining constant temperatures for support material B, and then in step F, the laminate of the resin film and support material B is shrunk. If this occurs, 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 higher, it is possible to easily increase dimensional change due to thermal expansion even with small temperature changes. On the other hand, by making the thermal expansion coefficient of support material B 230 ppm/K or lower, it is possible to reduce variation in dimensional change due to temperature variations in support material B.

The temperature to which the support material B is cooled is preferably 10°C or higher and 150°C or lower. Setting the temperature at 10°C or higher allows the use of a material with a low thermal expansion coefficient as support material B. A temperature of 30°C or higher is more preferable. Setting the temperature at 150°C or lower can suppress thermal degradation of support material B. Furthermore, the temperature of support material B can be increased and decreased in a short period of time. A temperature of 100°C or lower is more preferable.

When 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 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 stretch after lamination. The stretching amount in this case is preferably 0.2 to 1.5%. A stretching amount of 0.2% or more can further suppress warping when a laminate of resin film and substrate A is obtained in step E. On the other hand, a stretching amount of 1.5% or less can prevent wrinkles and cracks from occurring in the resin film during shrinkage in step F.

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

Examples of support material B include urethane gel sheets.

<Step D', Step 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.

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 component for a touch sensor. Examples of conductive patterns include a transparent conductive pattern made of indium tin oxide (ITO), or an opaque conductive pattern made by applying a conductive paste with silver particles dispersed in the resin. A conductive paste with dispersed silver particles can be made photosensitive, allowing for the formation of 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.

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.

<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 approximately 10 mm wide x approximately 10 μm thick.

To measure the modulus of elasticity, first determine the width of the test specimen using a vernier caliper and the thickness using a micrometer. Next, the resulting rectangular test specimen was tensile tested in a thermostatic chamber using an AG-5kNI tensile testing machine (Shimadzu Corporation) to secure the specimen with chucks approximately 10 mm above and below, giving a test length of 30 mm. The specimen was then stretched at 50 mm/min, and the modulus of elasticity 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.

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

<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. The amount of warping was recorded as positive when the laminate was convex downward, and negative when the laminate was convex upward. Measurements were made on 10 sheets, and the arithmetic average value was calculated.

<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.), and the cross section was 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 determined and expressed as the volume occupancy in the cross section as a percentage. The volume occupancy was determined by averaging 20 locations each on the first and second layer conductive patterns, a total of 40 locations.

<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 state, 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 state. This set of operations was repeated 50,000 times, and then the following conductivity evaluation and appearance inspection were carried out.

Conductivity Evaluation The resistance values of 20 locations each on the first and second conductive patterns, a total of 40 locations, were measured using a resistance meter (RM3544; manufactured by HIOKI) to determine the average, maximum, and minimum values. Resistance values above the upper limit of the resistance meter, 3.5 MΩ, were deemed unmeasurable and excluded from the calculation of the average value.

Visual Inspection If the conductive patterns of the first and second layers were free of cracks, peeling, and disconnections, they were judged as passed, otherwise they were judged as failed.

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 (manufactured by Mitsubishi Chemical Corporation)
[Photopolymerization initiator]
・IRGACURE 369 (manufactured by Ciba Japan Co., Ltd.)
[Silica dispersion]
・DMAC-ST (manufactured by Nissan Chemical).

(Synthesis Example 1)
Under a nitrogen stream, 100 g of NMP was placed in a 300 ml separable flask and heated and stirred until the temperature reached 55°C. 2.47 g of 1,4-bis(aminomethyl)cyclohexane and 4.31 g of 3,3'-diaminodiphenyl sulfone were added and dissolved in NMP. To this solution, 9.77 g of 4,4'-oxydiphthalic anhydride (ODPA) and 0.687 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) were added, 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 the mixture was stirred at room temperature for 60 minutes to obtain polyamic acid solution (A-1).

(Synthesis Example 2)
An acrylic copolymer of ethylenediamine (hereinafter referred to as "EA") / 2-ethylhexyl methacrylate (hereinafter referred to as "2-EHMA") / styrene (hereinafter referred to as "St") / acrylic acid (hereinafter referred to as "AA") (copolymerization ratio (parts by mass): 20/40/20/15) with 5 parts by mass of glycidyl methacrylate (hereinafter referred to as "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 to the reaction vessel over 1 hour. After completion of the dropwise addition, the polymerization reaction was continued for an additional 6 hours. Thereafter, 1 g of hydroquinone monomethyl ether was 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 completion of the dropwise addition, 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 an acrylic copolymer (B-1). The acid value of the resulting acrylic copolymer (B-1) was 103 mg KOH/g.

(Synthesis Example 3)
Into a 100 mL clean bottle were placed 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, and the mixture was mixed using a "Thinner Mixer" (ARE-310, manufactured by Thinky Corporation) to obtain 75.6 g of an overcoat solution (C-1).

(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 IRGACURE 369 (manufactured by Ciba Japan Co., Ltd.), and 8.0 g of CA were added and mixed using a "Thinner Mixer" (trade name, ARE-310, manufactured by Thinky Corporation) to obtain 20.6 g of photosensitive resin solution (total solids content 61.2% by mass). 10.0 g of the obtained photosensitive resin solution was mixed with 22.0 g of Ag particles having 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).

( 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 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 7 μm thick polyimide film. An overcoat solution (C-1) was applied to the entire surface of this polyimide film and dried at 90°C for 8 minutes in a hot air oven. After performing full-line exposure at an exposure dose of 200 mJ/cm ² (equivalent to a wavelength of 365 nm) using a PEM-6M exposure system (manufactured by Union Optical Co., Ltd.), the substrate was thermally cured at 230°C for 60 minutes in a hot air oven to form a 3 μm thick protective film, resulting in a 10 μm thick resin film. Then, a 150 mm square Intelimer tape CS2350NA4 (manufactured by Nitta Corporation) with a total thickness of 50 μm was laminated onto the resin film, and the resin film and Intelimer tape were then peeled off from the glass substrate. Then, using a lamination device SE650n (manufactured by Climb Products), a 50 μm thick self-adhesive PET film was laminated to the resin film side (the side peeled off from the glass substrate) of this peeled material. The Intelimer tape was then peeled off to obtain a laminate in which a 50 μm PET film was laminated to a 10 μm resin film.

( Reference example 2 )
The same procedure as in Example 1 was carried out, except that Intellimer Tape CS2325NA4 (manufactured by Nitta Corporation) having a total thickness of 25 μm was used instead of Intellimer Tape CS2350NA4 having a total thickness of 50 μm.

( Reference example 3 )
The same procedure as in Reference Example 1 was carried out except that Intelimer Tape CS2350NA3 was used instead of Intelimer Tape CS2350NA4.

( Comparative Reference Example 1 )
The same procedure as in Reference Example 1 was carried out except that PET was used instead of Intelimer Tape CS2325NA4.

The evaluation results of Reference Examples 1 to 3 and Comparative Reference Example 1 are shown in Table 1.

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 7 μm thick polyimide film. 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. This was followed by full-line exposure at an exposure dose of 200 mJ/cm ² (equivalent to a wavelength of 365 nm) using a PEM-6M exposure system (manufactured by Union Optical Co., Ltd.), followed by thermal curing at 230°C for 60 minutes in a hot air oven to form a 3 μm thick protective film, resulting in a resin film with a total thickness of 10 μm. The glass substrate and resin film were then maintained at 100°C, and a 5 mm thick self-adhesive urethane gel sheet (thermal expansion coefficient 93 ppm/K) preheated to 100°C was bonded to the resin film. While maintained 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. Using a bonding device SE650n (manufactured by Climb Products), a 50 μm thick self-adhesive PET film was bonded to the resin film side (the side separated from the glass substrate) of the peeled product. The urethane gel sheet was peeled off to obtain a laminate in which a 50 μm thick PET film was bonded to a 10 μm thick resin film.

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.

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.

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.

(Example 8)
The same procedure as in Example 4 was carried out except that a 0.5 mm thick PMMA sheet (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.

Example 9
The same procedure as in Example 4 was repeated, 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 lamination was set to 100°C to 150°C and the temperature after lamination was set to 25°C to 0°C.

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.

(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.

(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.

The evaluation results for Examples 4 to 10 and Comparative Examples 2 and 3 are shown in Table 2.

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 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 7 μm thick polyimide film. 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. A full-line exposure was performed using a PEM-6M exposure system (manufactured by Union Optical Co., Ltd.) at an exposure dose of 200 mJ/cm ² (equivalent to a wavelength of 365 nm), followed by thermal curing at 230°C for 60 minutes in a hot air oven to form a 3 μm thick protective film, resulting in a resin film with a total thickness of 10 μm. Using the jig shown in Figure 2, the urethane gel sheet was stretched uniformly by 0.69% in all directions along the surface. The urethane gel sheet in the 0.69% stretched state was then bonded to the resin film. The urethane gel sheet and resin film were then peeled from the interface between the glass substrate and the resin film, and the stretching of the urethane gel sheet was released to shrink the urethane gel sheet and resin film. A 50 μm-thick self-adhesive PET film was attached to the resin film side of this peeled product (the side that was peeled from the glass substrate). The urethane gel sheet was then peeled off to obtain a laminate in which a 50 μm-thick PET film was attached to a 10 μm-thick resin film.

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%.

(Comparative Example 4)
The same procedure as in Example 11 was carried out except that the stretching amount of the urethane gel sheet was 0.15%.

The evaluation results for Examples 11 and 12 and Comparative Example 4 are shown in Table 3.

( Reference example 4 )
The 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. Then, the substrate was thermally cured at 260 ° C for 60 minutes in a hot air oven 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 the substrate was dried in a drying oven at 100 ° C for 10 minutes to obtain a 1.0 μm thick coating film. As shown in FIG. 3, a photomask having 20 lattice-shaped light-transmitting portions consisting of a continuum of diamonds with a width of 3 μm and a diagonal length of 0.5 mm and 1.5 mm square light-transmitting portions at both ends, spaced 4 mm apart, was placed in the center of the substrate, and a full-line exposure was performed using a PEM-6M exposure device (manufactured by Union Optical Co., Ltd.) at an exposure dose of 200 mJ/cm ² (equivalent to a wavelength of 365 nm). The substrate was then immersed in a 0.1% by mass TMAH solution for 30 seconds for development, and 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 so as to cover only the grid-shaped portion, and the resulting solution was dried in a hot air oven at 90 ° C. for 8 minutes. Using an exposure system PEM-6M (manufactured by Union Optical Co., Ltd.), full line exposure was performed at an exposure dose of 200 mJ/cm ² (equivalent to a wavelength of 365 nm), followed by thermal curing in a hot air oven at 230°C for 60 minutes to form a first-layer protective film with a thickness of 3 μm. A second-layer conductive pattern was formed on the first-layer protective film using the same procedure as for the first-layer conductive pattern, so as to be perpendicular to the first-layer conductive pattern. An overcoat solution (C-1) was applied thereon to an area of 80 mm x 80 mm so as to cover only the grid-shaped portion of the conductive pattern, and then dried in a hot air oven at 90°C for 8 minutes. Using an exposure system PEM-6M (manufactured by Union Optical Co., Ltd.), full line exposure was performed at an exposure dose of 200 mJ/cm ² (equivalent to a wavelength of 365 nm), followed by thermal curing in a hot air oven at 210°C for 60 minutes to form a second-layer protective film with a thickness of 2 μm, thereby forming a touch sensor with the configuration shown in FIG. 4. Next, a 150 mm square Intellimer tape CS2350NA4 (manufactured by Nitta Corporation) with a total thickness of 50 μm was attached to 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 attached to the resin film side of the peeled product (the side separated from the glass substrate) using a lamination device SE650n (manufactured by Climb Products). The Intellimer tape was then peeled off to obtain a laminate in which a 50 μm PET film was attached to the touch sensor.

The evaluation results of Reference Example 4 are shown in Tables 4 and 5.

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

Claims (7)

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. 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. 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. The method for manufacturing a laminate described in claim 2, wherein the method for lowering the temperature of the laminate involves lowering the temperature of the laminate by 20 to 150°C. The method for manufacturing a laminate described in any one of claims 1 to 4, wherein the resin film is a laminate of two or more layers, including at least one layer made of transparent polyimide, and the resin film has an opaque conductive pattern with a line width of 1 μm to 9 μm. The method for manufacturing a laminate described in claim 5, wherein the opaque conductive pattern is composed of a mixture of metal and resin, and the proportion of resin in the opaque conductive pattern is 30 to 80 volume %. A method for manufacturing a component for a touch sensor, using a laminate obtained by the laminate manufacturing method described in claim 5 or claim 6 as the component.