JP7517341B2 - Manufacturing method of laminate - Google Patents

Description

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

In recent years, flexible applications for electronic devices such as smartphones and tablets have been considered, and there is a demand for thinner resin films with touch sensor functions, as well as image display materials such as organic light-emitting diode panels, liquid crystal panels, and electronic paper, in order to increase flexibility. A known manufacturing method for such devices is to form a resin film such as polyimide or COP (cycloolefin polymer) on a support material such as glass, form electrodes for touch sensors on the film, peel the resin film at the interface between the glass and the film, and then bond the film 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 and flexible electronic device (Patent Documents 1 to 3).

JP 2018-116859 A JP 2018-132768 A 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. In the conventional method of forming a resin film such as polyimide or COP (cycloolefin polymer) on a glass substrate, peeling it off from the glass substrate, and laminating it on a PET film or the like, there are problems with the resin film itself tearing due to the stress caused by peeling when it becomes thin, or handling becomes difficult due to its lack of stiffness.

It is therefore conceivable to form a resin film such as polyimide or COP (cycloolefin polymer) directly on the desired PET film. However, for example, polyimide film is generally obtained by applying polyimide dissolved in a solvent onto a PET film, drying it, and then ring-closing it as necessary. However, the volume shrinks due to the evaporation of the solvent and the dehydration reaction accompanying the ring-closing, and shrinkage stress occurs in the polyimide film. There was a problem that the laminate warped together with the thin PET film due to this shrinkage stress of the polyimide film. This is also the case with lamination by melt casting used for polyolefin film, etc., and there is a problem that the shrinkage stress occurs in the resin film due to the volume shrinkage when the molten resin cools and solidifies, causing warping of the laminate with the PET film.

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

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

The present invention is a method for producing a laminate comprising the steps of: 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 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 the 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 surface on which the support material B is provided;
and a step (step E) of peeling the laminate obtained in the step D at an interface between the support material B and the resin film to obtain a laminate of the resin film and the substrate A,
In the method for producing a laminate, when the elastic modulus of the resin film is Ea and the elastic modulus of the supporting 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 producing 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 along 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 (a) is a top view and (b) is a side view seen from side A.

As a result of their research, the inventors have come up with 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.

The following describes the form (hereinafter, "embodiment") for carrying out the method for manufacturing a laminate according to the present invention. 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 supporting material (supporting material B) to the surface of the resin film opposite to the surface on which the supporting material A is provided to obtain a laminate;
A step (step C) of peeling the laminate obtained in the 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 surface on which the support material B is provided;
and a step (step E) of peeling the laminate obtained in the step D at an 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 for obtaining a laminate of a resin film and a substrate (substrate A) on 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 them, polyimide is preferred from the viewpoint of flexibility and optical properties. Transparent polyimide having 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 an electrode, a light-emitting layer, an inorganic thin film, 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.

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.

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.

Examples of substrate A include PET film, PP (polypropylene) film, PE (polyethylene) film, OLED (Organic Light Emitting Diode) panel, polarizing plate, color filter, TFT (Thin Film Transistor) substrate, cover glass, etc.

<Step 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 tries 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 in the film.

Methods for forming a resin film include, for example, applying a varnish onto support material A, drying the applied varnish, exposing the resulting dried film to light, and heating the exposed film.

When the varnish is applied onto the support material A, the varnish contains a resin or a resin precursor, and may contain a solvent. There is no particular limitation on the type of solvent, and it can be appropriately selected according to the solubility of the resin used and the application method. One or a mixture of two or more of ester-based solvents, ketone-based, glycol ether-based, aliphatic, alicyclic, aromatic, alcohol-based, and water-based 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.

Methods for applying varnish include, for example, rotary application using a spinner, spray application, 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, a hot plate, infrared rays, etc., and vacuum drying. Heat drying is preferably performed at a temperature in the range of 50°C to 180°C for one minute to several hours.

The resulting dried film is then photocured by exposure to light. When performing exposure, a mercury lamp, LED, LD, xenon lamp, etc. can be used as the light source. Methods for thermal curing include heating and 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 of two or more layers, the same operation can be repeated to laminate them. The resin film used in the present invention may be a resin film, and may have a structure made of a material other than resin on the resin film as long as it does not impair the effects of the invention. 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 coater, slit die coater, gravure printing, flexographic printing, etc.

Support material A can be glass, quartz, alumina, zirconia, SUS, polyimide, acrylic, etc. When using a laser to peel support material A from the resin film in step C described below, glass is preferred because of its high light transmittance and heat resistance. A peeling layer may also be provided on the surface of support material A. By providing a peeling layer, the adhesion between support material A and the resin film is reduced, allowing it to be peeled off with little force in step C, making it easy to peel off.

<Step 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 surface on which support material A is provided, to obtain a laminate.

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

The elastic modulus Eb of the support material B should be 0.04 or less, as described below, but can be 10 ^6.0 Pa to 10 ^8.5 Pa in consideration of the elastic modulus of the resin film that can usually be taken. When the elastic modulus Eb of the 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 the support material B is 10 ^8.5 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. The elastic modulus Eb of the 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. When the thickness of support material B is 15 μm or more, it becomes easier to handle. On the other hand, when the thickness of support material B is 500 μm or less, the resin film is more likely to shrink together with support material B in step C, and the residual stress of the resin film can be further reduced. 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 the support material B does not shrink sufficiently in step C described below, and the residual stress in the resin film becomes large. As a result, warping occurs after the laminate of the resin film and the substrate A is formed in step E.

<Step C>
The method for producing 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 in the resin film.

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

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

The laminate obtained in step C and the substrate A can be bonded together using a bonding device by fixing the surfaces opposite to those to be bonded on an adsorption stage, joining the surfaces to be bonded together, and then releasing the fixation. When bonding, an easily deformable member such as a screen mesh can be used as the adsorption stage, and the layers can be bonded while rubbing with a roller or blade to prevent the generation of bubbles and wrinkles. Examples of devices for bonding include the manual sheet bonding machine SE650n (manufactured by Climb Products).

<Step 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 interface between the support material B and the resin film from the laminate obtained in step D. 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, the method comprising 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 supporting material (supporting material B) to the surface of the resin film opposite to the surface on which the supporting 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 the step B at the interface thereof 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') of bonding 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;
The method includes a step (step E') of obtaining a laminate of the resin film and the substrate A by peeling the support material B and the resin film from the laminate obtained in the step D' at the interface between them.

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 the support material B by 2000 ppm or more. This step relieves the residual stress in the resin film. If the amount of shrinkage of the laminate of the resin film and the support material B is less than 2000 ppm, warping is likely to occur when a laminate of the resin film and the substrate A is obtained in step E. The amount of shrinkage of the laminate of the resin film and the support material B is more preferably 4000 ppm or more.

Methods for shrinking the laminate of the resin film and supporting material B include lowering the temperature of the laminate of the resin film and supporting material B, and laminating a laminate of supporting material A and the resin film to supporting material B that has been stretched in advance, then allowing supporting material A to peel off, and then shrinking supporting material B to which the resin film has been laminated. The significance of stretching supporting material B here is that it expands its surface area by applying heat or external force, and then removes residual stress in the resin film that is laminated by the restoration of its original shape when the heat or external force is removed.

When lowering the temperature of the laminate of the resin film and the support material B, the laminate of the resin film and the support material B can be made 2000 ppm or more by adjusting the temperature to be lowered according to the thermal expansion coefficient of the support material B. Examples of the support material B include urethane gel, silicon gel, PMMA (polymethyl methacrylate), magnesium alloy AZ91, etc. In addition, a separate adhesive layer may be provided on the support material B. This allows even a material that does not have adhesive properties to be used as the support material B.

In step B, when supporting material A and the resin film are bonded together while maintaining constant temperatures for supporting material B, and then the laminate of the resin film and supporting material B is shrunk in step F, it is preferable that supporting material B has a thermal expansion coefficient of 20 ppm/K to 230 ppm/K. By making supporting material B's thermal expansion coefficient 20 ppm/K or more, it is possible to easily increase the dimensional change due to thermal expansion even with a small temperature change. On the other hand, by making supporting material B's thermal expansion coefficient 230 ppm/K or less, it is possible to reduce the variation in dimensional change associated with temperature variation in supporting material B.

The temperature to which it is lowered during cooling is preferably 10°C or higher and 150°C or lower. By setting the temperature at 10°C or higher, a material with a small thermal expansion coefficient can be used as support material B. It is more preferable that the temperature be 30°C or higher. Furthermore, by setting the temperature at 150°C or lower, it is possible to suppress thermal deterioration of support material B. Furthermore, it is possible to raise and lower the temperature of support material B in a short period of time. It is more preferable that the temperature be 100°C or lower.

In the case where a laminate of a support material A and a resin film is laminated to a support material B that has been stretched in advance, the support material A is peeled off, and then the support material B with the laminated resin film is shrunk to shrink the laminate of the resin film and the support material B by 2000 ppm or more, a method of stretching the support material B in advance and shrinking it after lamination includes a method of stretching the support material B using a jig and releasing the stretching after lamination. The stretching amount at this time 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 the resin film and the substrate A is obtained in step E. On the other hand, by setting the stretching amount to 1.5% or less, it is possible to prevent wrinkles and cracks from occurring in the resin film during shrinkage in step F.

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 toward the outside by turning the screw 21 while fixing the guide 22. 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 toward the outside. It is preferable to stretch the support material B24 evenly in all directions.

Examples of support material B include urethane gel sheets.

<Step D' and Step E'>
The laminate after step F can be subjected to the same methods as those described in the sections on steps D and E. 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 member for a touch sensor. Examples of the conductive pattern include a transparent conductive pattern such as indium tin oxide (ITO), and an opaque conductive pattern formed by applying a conductive paste in which silver particles are dispersed to a resin. A conductive paste in which silver particles are dispersed can be 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.

The present invention will be described in detail below with reference to examples and comparative examples, but the aspects of the present invention are not limited to these.

<Measurement of Elastic Modulus>
Using a method similar to that described in the Examples, a resin film having a total thickness of 10 μm was formed on an alkali-free glass substrate, consisting of two layers: a 7 μm-thick polyimide film and a 3 μm-thick protective film. Then, a single-edged razor was used to make a rectangular cut in the resin film measuring 50.4 mm in length and 10.1 mm in width, and the cut was peeled off from the substrate to obtain a resin film test piece measuring approximately 50 mm in length, approximately 10 mm in width, and approximately 10 μm in thickness.

To measure the elastic modulus, first the width of the test piece was measured using a vernier caliper, and then the thickness of the test piece was measured using a micrometer. Next, the obtained rectangular test piece was chucked at approximately 10 mm above and below the test piece to give a test length of 30 mm, and pulled at 50 mm/min using an in-temperature bath tensile tester AG-5kNI (manufactured by Shimadzu Corporation), and the elastic modulus was calculated from the slope of the stress-strain curve in the 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 cut to prepare strips, and the elastic modulus was measured in the same manner.

<Warpage 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 down, and the maximum height from the stage was measured with a vernier caliper. The amount of warping was positive when the laminate was downwardly convex, and negative when the laminate was upwardly convex. The measurement was performed on 10 sheets, and the arithmetic average value was calculated.

<Measurement of the percentage of resin 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 identified, and the areas of the metal and resin in the cross section were determined, and the volume occupancy in the cross section was calculated as a percentage. The volume occupancy was calculated by averaging 20 locations each of the first and second layers of the conductive pattern, a total of 40 locations.

<Touch sensor evaluation>
The laminate provided with the conductive pattern was folded 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 folded 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 of the first and second conductive patterns, a total of 40 locations, were measured with a resistance meter (RM3544; manufactured by HIOKI) to determine the average, maximum, and minimum values. When the resistance meter's upper limit of measurement, 3.5 MΩ, was exceeded, it was deemed unmeasurable and was 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, or 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 Chiba Japan Co., Ltd.)
[Silica dispersion]
・DMAC-ST (manufactured by Nissan Chemical).

(Synthesis Example 1)
Under a nitrogen stream, 100 g of NMP was added to 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'-diaminodiphenylsulfone 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 obtained solution and stirred at room temperature for 60 minutes to obtain a polyamic acid solution (A-1).

(Synthesis Example 2)
An acrylic copolymer of ethylenediamine (hereinafter, "EA")/2-ethylhexyl methacrylate (hereinafter, "2-EHMA")/styrene (hereinafter, "St")/acrylic acid (hereinafter, "AA") (copolymerization ratio (parts by mass): 20/40/20/15) was reacted with 5 parts by mass of glycidyl methacrylate (hereinafter, "GMA") In a reaction vessel in a nitrogen atmosphere, 150 g of DMEA was charged, and the temperature was raised 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 dropped into the reaction vessel over 1 hour. After the dropwise addition, the polymerization reaction was carried out for another 6 hours. Then, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. Subsequently, a mixture consisting of 5 g of GMA, 1 g of triethylbenzylammonium chloride, and 10 g of DMEA was dropped into the reaction vessel over 0.5 hours. After the dropwise addition, the addition reaction was carried out for another 2 hours. The obtained reaction solution was purified with methanol to remove unreacted impurities, and further vacuum dried for 24 hours to obtain an acrylic copolymer (B-1). The acid value of the obtained 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 mixed using a Thinky 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 IRGACURE369 (manufactured by Ciba Japan Co., Ltd.), and 8.0 g of CA were added and mixed with "Awatori Rentaro" (trade name, ARE-310, manufactured by Thinky Corporation) to obtain 20.6 g of photosensitive resin solution (total solid 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).

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. Then, heat curing was performed 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. After performing full line exposure at an exposure dose of 200 mJ / cm ² (wavelength 365 nm conversion) using an exposure device PEM-6M (manufactured by Union Optical Co., Ltd.), heat curing was performed in a hot air oven at 230 ° C. for 60 minutes to form a protective film with a thickness of 3 μm, thereby obtaining a resin film with a thickness of 10 μm. Then, Intellimer tape CS2350NA4 (manufactured by Nitta Corporation) with a total thickness of 50 μm was laminated on the resin film with a size of 150 mm square, and then the resin film and Intellimer tape were peeled off from the glass substrate. Then, using a lamination device SE650n (manufactured by Climb Products), a PET film having a thickness of 50 μm and self-adhesive was laminated on the resin film side (the side on which the glass substrate is peeled off) of the peeled off product. Furthermore, by peeling off the Intellimer tape, a laminate in which a 50 μm PET film was laminated on a 10 μm resin film was obtained.

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.

Example 3
The same procedure as in Example 1 was repeated except that Intellimer tape CS2350NA3 was used instead of Intellimer tape CS2350NA4.

(Comparative Example 1)
The same procedure as in Example 1 was repeated except that PET was used instead of Intellimer tape CS2325NA4.

The evaluation results for Examples 1 to 3 and Comparison 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 in a hot air oven at 90 ° C. for 15 minutes. Then, heat curing was performed 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. Then, a full line exposure was performed using an exposure device PEM-6M (manufactured by Union Optical Co., Ltd.) at an exposure dose of 200 mJ / cm ² (wavelength 365 nm equivalent), and then heat curing was performed in a hot air oven at 230 ° C. for 60 minutes to form a protective film with a thickness of 3 μm, thereby obtaining a resin film with a total thickness of 10 μm. Thereafter, the glass substrate and the resin film were held at 100°C, and a 5 mm thick urethane gel sheet (thermal expansion coefficient 93 ppm/K) having self-adhesiveness, which had been heated to 100°C in advance, was attached to the resin film. While held at 100°C, the urethane gel sheet and the resin film were separated from the interface between the glass substrate and the resin film, and the urethane gel sheet and the resin film were cooled to 25°C. Using a lamination device SE650n (manufactured by Climb Products), a 50 μm thick PET film having self-adhesiveness was attached to the resin film side (the side peeled from the glass substrate) of this peeled product. By peeling off the urethane gel sheet, a laminate in which a 50 μm PET film was attached to a 10 μm resin film was obtained.

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 repeated, except that a 5 mm thick silicon gel sheet (coefficient of thermal expansion: 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 (coefficient of thermal expansion: 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, 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 to 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 in a hot air oven at 90 ° C. for 15 minutes. Then, heat curing was performed 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. After performing full line exposure at an exposure dose of 200 mJ / cm ² (converted to a wavelength of 365 nm) using an exposure device PEM-6M (manufactured by Union Optical Co., Ltd.), heat curing was performed in a hot air oven at 230 ° C. for 60 minutes to form a protective film with a thickness of 3 μm, thereby obtaining a resin film with a total thickness of 10 μm. Using the jig shown in FIG. 2, the urethane gel sheet was stretched by 0.69% evenly in all directions in the surface direction. The urethane gel sheet in the 0.69% stretched state was attached onto the resin film. Thereafter, the urethane gel sheet and the resin film were peeled off from the interface between the glass substrate and the resin film, and the stretching of the urethane gel sheet was released to cause the urethane gel sheet and the resin film to shrink. A 50 μm thick self-adhesive PET film was attached to the resin film side (the side peeled off from the glass substrate) of this peeled off product. Furthermore, the urethane gel sheet was 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 stretch 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 stretch amount of the urethane gel sheet was 0.15%.

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

(Example 13)
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. Then, heat curing was performed in a hot air oven at 260 ° C. for 60 minutes to form a polyimide film with a thickness of 7 μm. 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 coating film with a thickness of 1.0 μm. As shown in FIG. 3, a photomask having 20 patterns at 4 mm intervals, each pattern having a lattice-shaped light-transmitting portion consisting of a rhombic continuum with a width of 3 μm and a diagonal length of 0.5 mm and a light-transmitting portion of 1.5 mm square at both ends, was placed in the center of the substrate, and a full-line exposure was performed at an exposure dose of 200 mJ/cm ² (converted to a wavelength of 365 nm) using an exposure device PEM-6M (manufactured by Union Optical Co., Ltd.), and then the substrate was immersed in a 0.1 mass% TMAH solution for 30 seconds to perform development, and a rinse treatment was performed with ultrapure water to obtain a precursor of a conductive pattern. Then, the substrate was 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 thereon to an area of 80 mm×85 mm so as to cover only the lattice-shaped portion of the conductive pattern, and the conductive pattern was dried in a hot air oven at 90° C. for 8 minutes. After performing full line exposure at an exposure dose of 200 mJ/cm ² (wavelength 365 nm equivalent) using an exposure device PEM-6M (manufactured by Union Optical Co., Ltd.), thermal curing was performed 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 in the same procedure as the first layer conductive pattern so as to be mutually 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 lattice-shaped portion of the conductive pattern, 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 (wavelength 365 nm equivalent) using an exposure device PEM-6M (manufactured by Union Optical Co., Ltd.), thermal curing was performed 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 having the configuration shown in FIG. 4. Then, Intellimer tape CS2350NA4 (manufactured by Nitta Corporation) with a total thickness of 50 μm was attached to the touch sensor in a size of 150 mm square, and then the resin film and Intellimer tape were peeled off from the glass substrate. Then, using a bonding device SE650n (manufactured by Climb Products), a PET film with a thickness of 50 μm was attached to the resin film side (the side peeled off from the glass substrate) of this peeled off product. Furthermore, by peeling off the Intellimer tape, a laminate in which a 50 μm PET film was attached to the touch sensor was obtained.

The evaluation results of Example 13 are shown in Tables 4 and 5.

11 Support material A
12 Resin film 13 Support material B
14 Substrate A
21 Screw 22 Guide 23 Clamp 24 Support 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 (4)

A method for producing a laminate for obtaining a laminate of a resin film and a substrate (substrate A) on which the resin film is to be laminated, comprising 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 supporting material (supporting material B) to the surface of the resin film opposite to the surface on which the supporting material A is provided to obtain a laminate;
A step (step C) of peeling the laminate obtained in the 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 surface on which the support material B is provided;
and a step (step E) of peeling the laminate obtained in the step D at an interface between the support material B and the resin film to obtain a laminate of the resin film and the substrate A,
A method for producing a laminate, wherein Eb/(Ea+Eb) is 0.04 or less, where Ea is the tensile modulus of elasticity of the resin film and Eb is the tensile modulus of elasticity of the support material B. 2. 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. 3. The method for producing a laminate according to claim 2 , 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 producing a member for a touch sensor , comprising using the laminate obtained by the method for producing a laminate according to claim 2 or 3 as a member.

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