JP2020001381A - Method for producing transparent resin film - Google Patents

Abstract

To provide a method for producing a transparent resin film which can obtain a homogeneous transparent resin film.SOLUTION: A method for producing a transparent resin film includes: a step of holding each of both ends of a transparent resin film that includes at least one resin selected from the group consisting of a polyimide-based resin and a polyamide-based resin and has a long strip shape; a step of conveying the held film; a step of setting the width of the held film to a predetermined width, subjecting the resin film to heat treatment in a drier, and setting a ratio of the width of the film after heat treatment to the width of the film before heat treatment to 1.1 or less; and a step of releasing holding of the resin film taken out of the drier.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a transparent resin film.

  In a flexible display device, a transparent resin film instead of glass is required. As a material of such a transparent resin film, a material having transparency and mechanical strength, such as a polyimide resin or a polyamide resin, is known.

  In the production of such a transparent resin film, a heat treatment of the resin film may be performed in order to obtain a desired quality (for example, see Patent Document 1).

  By the way, when such a heat treatment is performed, uniformity of the obtained transparent resin film may not be obtained.

JP 2010-36414 A

  The present invention has been proposed in view of such circumstances, and has as its object to provide a method for producing a transparent resin film having good homogeneity even when heat treatment is performed.

That is, the present invention provides the following.
[1] a step of gripping both ends of a long strip-shaped transparent resin film containing at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, a step of transporting the gripped film, A step of setting the width of the gripped film to a predetermined distance, heat-treating the resin film in a dryer, and adjusting the ratio of the width of the film after the heat treatment to the width of the film before the heat treatment to 1.1 or less; A method for producing a transparent resin film, comprising a step of releasing the grip of the resin film coming out of the film.
[2] The method according to [1], wherein the ratio of the width of the film after the heat treatment to the width of the film before the heat treatment is 0.7 to 1.0.
[3] The manufacturing method according to [1] or [2], wherein the holding is performed by a plurality of clips.
[4] The manufacturing method according to [3], wherein the driving device to which the clip is attached moves at the same speed as the transport speed of the film.
[5] The manufacturing method according to [4], wherein the driving device is driven by a chain.
[6] The method according to any one of [3] to [5], wherein a space between adjacent clips is 1 to 20 mm.
[7] When a straight line perpendicular to the film transport axis is aligned with the center of the grip portion of the clip at one end of the film, the intersection of the straight line and the other end of the film, and the center of the grip portion of the clip at the other end of the film. The manufacturing method according to any one of [3] to [6], wherein the distance is 3 mm or less.
[8] The method according to any one of [1] to [7], wherein the content of the organic solvent in the resin film after the heat treatment is 0.001 to 3% by mass based on the mass of the resin film. .
[9] The production method according to any one of [1] to [8], comprising a step of slitting both ends of the film after releasing the grip of the film.
[10] The production method according to [9], further comprising a step of laminating a protective film on the resin film after slitting the film.
[11] The production method according to [10], comprising a step of slitting the resin film to which the protective film is bonded after bonding the protective film.
[12] The production method according to [10] or [11], comprising a step of winding the resin film around a roll after laminating the protective film.

  As described above, the present invention provides a method for producing a transparent resin film capable of obtaining a homogeneous transparent resin film.

The example of the dryer which concerns on manufacture of the transparent resin film concerning this invention is shown. The film is transported from left to right on the paper. (A) shows a side perspective view of the dryer, and the center line shows the situation in which the film is conveyed. (B) is a top perspective view of the dryer, and a square in the center shows a state in which the film is transported.

  The materials, dimensions, and the like illustrated in the following description are merely examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes without departing from the scope of the invention.

  The present invention includes a step of gripping both ends of a long strip-shaped transparent resin film including at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, and a step of transporting the gripped film. A process in which the width of the gripped film is set to a predetermined distance, the resin film is heat-treated in a dryer, and the ratio of the width of the film after heat treatment to the width of the film before heat treatment is 1.1 or less, and drying. Provided is a method for manufacturing a transparent resin film having a step of releasing a grip of a resin film coming out of a machine.

[Polyimide resin, polyamide resin]
The transparent resin film of the present invention contains at least one resin selected from the group consisting of a polyimide resin and a polyamide resin. Polyimide-based resin is a polymer containing a repeating structural unit containing an imide group (hereinafter sometimes referred to as polyimide), and a polymer containing a repeating structural unit containing both an imide group and an amide group (hereinafter, referred to as polyimide) , May be described as polyamideimide) at least one polymer selected from the group consisting of Further, the polyamide-based resin refers to a polymer containing a repeating structural unit containing an amide group.

  The polyimide resin preferably has a repeating structural unit represented by the formula (10). Here, G is a tetravalent organic group, and A is a divalent organic group. The polyimide-based resin may include two or more types of repeating structural units represented by the formula (10) having different G and / or A.

  The polyimide resin contains at least one selected from the group consisting of repeating structural units represented by Formula (11), Formula (12), and Formula (13) as long as various physical properties of the transparent resin film are not impaired. It may be.

In the formulas (10) and (11), G and G ¹ are each independently a tetravalent organic group, and may be preferably substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. Organic group. As G and G ¹ , Equation (20), Equation (21), Equation (22), Equation (23), Equation (24), Equation (25), Equation (26), Equation (27), and Equation (28) ) Or a group represented by the formula (29) and a tetravalent chain hydrocarbon group having 6 or less carbon atoms. Since it is easy to suppress the yellowness (YI value) of the transparent resin film, Equation (20), Equation (21), Equation (22), Equation (23), Equation (24), Equation (25), A group represented by the formula (26) or (27) is preferable.

In equations (20) to (29),
* Represents a bond,
Z is a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 -, - _{Ar -, - SO 2 -,} - CO -, - O-Ar-O -, - Ar-O-Ar -, - Ar-CH 2 -Ar -, - Ar-C (CH 3) 2 -Ar- , or It represents a _-Ar-SO 2 -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms which may be substituted by a fluorine atom, and specific examples include a phenylene group.

In the formula (12), G ² is a trivalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. The G ^2, equation (20), equation (21), equation (22), equation (23), equation (24), equation (25), equation (26), equation (27), equation (28) or Examples thereof include a group in which one of the bonding hands of the group represented by the formula (29) is replaced by a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms.

In the formula (13), G ³ is a divalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As G ³ , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28), or Among the bonds of the group represented by the formula (29), a group in which two non-adjacent atoms are replaced by hydrogen atoms and a chain hydrocarbon group having 6 or less carbon atoms are exemplified.

In the formulas (10) to (13), A, A ¹ , A ² and A ³ are each independently a divalent organic group, preferably a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group which may be substituted. As A, A ¹ , A ² and A ³ , the equations (30), (31), (32), (33), (34), (35), (36), (36) 37) or a group represented by the formula (38); a group obtained by substituting the group with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

In Equations (30) to (38),
* Represents a bond,
Z ^{1, Z 2} and ^{Z 3} are each independently a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 —, —C (CF ₃ ) ₂ —, —SO ₂ — or —CO—.
One example is when Z ¹ and Z ³ are —O— and Z ² is —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or —SO ₂ —. is there. The bonding position of each of Z ¹ and Z ² with respect to each ring and the bonding position of each of Z ² and Z ³ with respect to each ring are preferably at the meta position or the para position, respectively.

  The polyimide resin is preferably a polyamideimide having at least a repeating structural unit represented by the formula (10) and a repeating structural unit represented by the formula (13) from the viewpoint of easily improving visibility. The polyamide resin preferably has at least a repeating structural unit represented by the formula (13).

  In one embodiment of the present invention, the polyimide-based resin comprises a diamine and a tetracarboxylic acid compound (an acid chloride compound, a tetracarboxylic acid compound analog such as tetracarboxylic dianhydride), and if necessary, a dicarboxylic acid compound. (An analog of a dicarboxylic acid compound such as an acid chloride compound), and a condensation-type polymer obtained by reacting (polycondensation) a tricarboxylic acid compound (an analog of a tricarboxylic acid compound such as an acid chloride compound or a tricarboxylic anhydride). . The repeating structural unit represented by the formula (10) or (11) is generally derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by the formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

  In one embodiment of the present invention, the polyamide resin is a condensation type polymer obtained by reacting (polycondensing) a diamine and a dicarboxylic acid compound. That is, the repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

  Examples of the tetracarboxylic acid compound include an aromatic tetracarboxylic acid compound such as an aromatic tetracarboxylic dianhydride; and an aliphatic tetracarboxylic acid compound such as an aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compounds may be used alone or in combination of two or more. The tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound in addition to the dianhydride.

  Specific examples of the aromatic tetracarboxylic dianhydride include 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3 3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane Dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 1,2-bis ( , 3-Dicarboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride and 4 4,4 '-(p-phenylenedioxy) diphthalic dianhydride and 4,4'-(m-phenylenedioxy) diphthalic dianhydride. These can be used alone or in combination of two or more.

  Examples of the aliphatic tetracarboxylic dianhydride include cyclic and acyclic aliphatic tetracarboxylic dianhydrides. The cycloaliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride. A cycloalkanetetracarboxylic dianhydride such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2 .2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3 ′, 4,4′-tetracarboxylic dianhydride and positional isomers thereof. Can be These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride. These can be used alone or in combination of two or more. Further, a combination of a cycloaliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used.

  Among the above-mentioned tetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydride and bicyclo [2.2.2] oct-7-ene from the viewpoint of high transparency and low coloring property. Preferred are -2,3,5,6-tetracarboxylic dianhydride and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof. Further, as the tetracarboxylic acid, a water adduct of an anhydride of the above tetracarboxylic acid compound may be used.

Examples of the tricarboxylic acid compound include an aromatic tricarboxylic acid, an aliphatic tricarboxylic acid, and an acid chloride compound and an acid anhydride thereof, and two or more kinds thereof may be used in combination.
Specific examples include 1,2,4-benzenetricarboxylic anhydride of tricarboxylic acid; 2,3,6-naphthalene tricarboxylic acid-2,3-anhydride; and phthalic anhydride and benzoic acid is a single bond, -CH _{2 -, - C (CH 3)} 2 -, - C (CF 3) 2 -, - SO 2 - or a compound linked phenylene group.

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related acid chloride compounds and acid anhydrides, and two or more of them may be used in combination.
Specific examples thereof include terephthalic acid dichloride (terephthaloyl chloride (TPC)); isophthalic acid dichloride; naphthalene dicarboxylic acid dichloride; 4,4′-biphenyl dicarboxylic acid dichloride; 3,3′-biphenyl dicarboxylic acid dichloride; , 4'-oxybis (benzoyl chloride) (OBBC); dicarboxylic acid compound of the chain hydrocarbon is 8 or less carbon atoms and two benzoic acid single _{bond, -CH 2 -, - C (} CH 3) 2 -, Compounds linked by —C (CF ₃ ) ₂ —, —SO ₂ — or a phenylene group are exemplified.

  Examples of the diamine include an aliphatic diamine, an aromatic diamine, and a mixture thereof. In the present embodiment, “aromatic diamine” refers to a diamine in which an amino group is directly bonded to an aromatic ring, and a part of the structure may include an aliphatic group or another substituent. The aromatic ring may be a single ring or a condensed ring, and is exemplified by, but not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, the aromatic ring is preferably a benzene ring. The “aliphatic diamine” refers to a diamine in which an amino group is directly bonded to an aliphatic group, and may have an aromatic ring or another substituent in a part of its structure.

  Examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylene diamine and 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4,4′-diamine. And cycloaliphatic diamines such as diaminodicyclohexylmethane. These can be used alone or in combination of two or more.

  Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2,6-diaminonaphthalene. Aromatic diamines having one aromatic ring such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenylether, 3,3 ' -Diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis ( 4-aminophenoxy) benzene, 4,4'-diaminodife Sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2, 2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2′-dimethylbenzidine, 2,2′-bis (trifluoromethyl) benzidine (2,2′-bis (trifluoromethyl) -4 , 4'-Diaminodiphenyl (TFMB)), 4,4'-bis (4-aminophenoxy) biphenyl, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3- Methylphenyl) fluorene, 9,9-bis (4-amino-3-chlorophenyl) fluorene, 9,9-bis (4-amino-3-fluorophenyl) Such as fluorene, and aromatic diamines having two or more aromatic rings. These can be used alone or in combination of two or more.

  Among the above diamines, from the viewpoint of high transparency and low coloring property, it is preferable to use at least one selected from the group consisting of aromatic diamines having a biphenyl structure, and 2,2′-dimethylbenzidine, 2,2 More preferably, at least one selected from the group consisting of '-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenyl ether is used, More preferably, '-bis (trifluoromethyl) benzidine is used.

  Polyimide-based resin, the above diamine, tetracarboxylic acid compound, tricarboxylic acid compound, each method such as dicarboxylic acid compound in a conventional manner, for example, after mixing by a method such as stirring, the resulting intermediate imidation catalyst and It can be obtained by imidization in the presence of a dehydrating agent if necessary. The polyamide resin is obtained by mixing the respective raw materials such as the diamine and the dicarboxylic acid compound by a conventional method, for example, a method such as stirring.

  The imidization catalyst used in the imidation step is not particularly limited, and examples thereof include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, and N-butylpyrrolidine. , N-butylpiperidine, and alicyclic amines (monocyclic) such as N-propylhexahydroazepine; azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2] .2] octane and an alicyclic amine (polycyclic) such as azabicyclo [3.2.2] nonane; and 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3- Ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3 4 cyclopentenopyridine pyridine, 5,6,7,8-tetrahydroisoquinoline, and aromatic amines isoquinoline.

  The dehydrating agent used in the imidization step is not particularly limited, and includes, for example, acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, isovaleric anhydride and the like.

In the mixing of the raw materials and the imidization step, the reaction temperature is not particularly limited, but is, for example, 15 to 350 ° C, and preferably 20 to 100 ° C. Although the reaction time is not particularly limited, it is, for example, about 10 minutes to 10 hours. If necessary, the reaction may be performed under an inert atmosphere or under reduced pressure. The reaction may be carried out in a solvent, and examples of the solvent include those exemplified as a solvent used for preparing a varnish. After the reaction, the polyimide resin or the polyamide resin is purified. As a purification method, for example, a method of adding a poor solvent to the reaction solution, precipitating a resin by a reprecipitation method, drying and taking out a precipitate, washing the precipitate with a solvent such as methanol if necessary, and drying. No.
For the production of the polyimide resin, for example, a production method described in JP-A-2006-199945 or JP-A-2008-163107 may be referred to. Commercially available polyimide resins can also be used, and specific examples thereof include NeoPrim (registered trademark) manufactured by Mitsubishi Gas Chemical Company, Inc., and KPI-MX300F manufactured by Kawamura Sangyo Co., Ltd.

  The weight average molecular weight (Mw) of the polyimide resin or the polyamide resin is preferably 200,000 or more, more preferably 250,000 or more, still more preferably 300,000 or more, preferably 600,000 or less, more preferably Is less than 500,000. As the weight average molecular weight of the polyimide-based resin or polyamide-based resin is larger, there is a tendency that a higher bending resistance when formed into a film is more likely to be exhibited. Therefore, from the viewpoint of increasing the bending resistance of the transparent resin film, the weight average molecular weight is preferably equal to or more than the above lower limit. On the other hand, as the weight average molecular weight of the polyimide resin or the polyamide resin is smaller, the viscosity of the varnish tends to be lower and the processability tends to be improved. In addition, the stretchability of a polyimide resin or a polyamide resin tends to be improved. Therefore, from the viewpoint of processability and stretchability, the weight average molecular weight is preferably equal to or less than the above upper limit. In the present application, the weight average molecular weight can be determined by gel permeation chromatography (GPC) measurement and converted into standard polystyrene, and can be calculated, for example, by the method described in Examples.

  The imidation ratio of the polyimide resin is preferably 95 to 100%, more preferably 97 to 100%, further preferably 98 to 100%, and particularly preferably 100%. From the viewpoints of the stability of the varnish and the mechanical properties of the obtained transparent resin film, it is preferable that the imidization ratio is not less than the above lower limit. The imidation ratio can be determined by an IR method, an NMR method, or the like. From the above viewpoint, the imidation ratio of the polyimide resin contained in the varnish is preferably within the above range. The imidation ratio can be determined, for example, by the method described in Japanese Patent Application No. 2018-007523.

  In a preferred embodiment of the present invention, the polyimide resin or the polyamide resin contained in the transparent resin film of the present invention contains a halogen atom such as a fluorine atom, which can be introduced by, for example, the above-mentioned fluorine-containing substituent. Is fine. When the polyimide-based resin or the polyamide-based resin contains a halogen atom, it is easy to improve the elastic modulus of the transparent resin film and to reduce the yellowness (YI value). When the elastic modulus of the transparent resin film is high, generation of scratches and wrinkles in the film is easily suppressed, and when the yellowness of the transparent resin film is low, the transparency of the film is easily improved. The halogen atom is preferably a fluorine atom. Preferred fluorine-containing substituents for containing a fluorine atom in the polyimide resin or the polyamide resin include, for example, a fluoro group and a trifluoromethyl group.

  The content of halogen atoms in the polyimide-based resin or polyamide-based resin is preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and still more preferably 5 to 40% by mass, based on the mass of the polyimide-based resin or polyamide-based resin. 30% by mass. When the content of the halogen atom is 1% by mass or more, the elasticity at the time of forming a film is further improved, the water absorption is reduced, the yellowness (YI value) is further reduced, and the transparency is more easily improved. When the content of the halogen atom is 40% by mass or less, the synthesis may be easily performed.

  In one embodiment of the present invention, the content of the polyimide resin and / or the polyamide resin in the transparent resin film is preferably 40% by mass or more, more preferably 50% by mass, based on the total mass of the transparent resin film. The content is more preferably 70% by mass or more. It is preferable that the content of the polyimide-based resin and / or the polyamide-based resin is not less than the above lower limit, from the viewpoint of easily increasing the flex resistance and the like. The content of the polyimide resin and / or the polyamide resin in the transparent resin film is usually 100% by mass or less based on the total mass of the transparent resin film.

[Additive]
The transparent resin film of the present invention may further include an additive such as a filler. Such additives include, for example, silica particles, ultraviolet absorbers, brighteners, silica dispersants, antioxidants, pH adjusters, and leveling agents.

(Silica particles)
The transparent resin film of the present invention may further contain silica particles as an additive. The content of the silica particles is preferably at least 1 part by mass, more preferably at least 3 parts by mass, still more preferably at least 5 parts by mass, preferably at most 60 parts by mass, more preferably at most 60 parts by mass, based on 100 parts by mass of the transparent resin film. Is 50 parts by mass or less, more preferably 45 parts by mass or less. Further, the content of the silica particles can be arbitrarily selected from the upper limit value and the lower limit value and combined with the upper limit value. When the content of the silica particles is in the numerical range of the upper limit value and / or the lower limit value, in the transparent resin film of the present invention, the silica particles hardly aggregate and tend to be uniformly dispersed in a state of primary particles. The visibility of the transparent resin film of the present invention can be prevented from lowering.

  The particle size of the silica particles is preferably at least 1 nm, more preferably at least 3 nm, further preferably at least 5 nm, particularly preferably at least 8 nm, preferably at most 30 nm, more preferably at most 28 nm, even more preferably at most 25 nm, particularly preferably at most 25 nm. Preferably it is 20 nm or less. The particle diameter of the silica particles can be selected from any of the upper and lower limits and combined with the upper and lower limits. When the content of the silica particles is in the numerical range of the upper limit value and / or the lower limit value, the transparent resin film of the present invention hardly interacts with light having a specific wavelength in white light. A decrease in visibility can be suppressed. In the present specification, the particle diameter of the silica particles indicates an average primary particle diameter. The particle size of the silica particles in the transparent resin film can be measured by imaging using a transmission electron microscope (TEM). The particle size of the silica particles before producing the transparent resin film (for example, before adding to the varnish) can be measured by a laser diffraction type particle size distribution meter.

  Examples of the form of the silica particles include a silica sol in which the silica particles are dispersed in an organic solvent and the like, and a silica powder prepared by a gas phase method. Among these, silica sol is preferred from the viewpoint of workability.

The silica particles may be subjected to a surface treatment, for example, silica particles obtained by substituting a solvent (more specifically, γ-butyrolactone) from a water-soluble alcohol-dispersed silica sol.
The water-soluble alcohol is an alcohol having 3 or less carbon atoms per hydroxy group in one water-soluble alcohol molecule, and includes methanol, ethanol, 1-propanol, and 2-propanol. Depending on the compatibility between the silica particles and the type of the polyimide polymer, usually, when the silica particles are subjected to a surface treatment, the compatibility with the polyimide polymer contained in the transparent resin film is improved, and the dispersibility of the silica particles is improved. Since it tends to improve, it is possible to suppress a decrease in visibility according to the present invention.

(UV absorber)
The transparent resin film in the present invention may further contain an ultraviolet absorber. For example, a triazine-based UV absorber, a benzophenone-based UV absorber, a benzotriazole-based UV absorber, a benzoate-based UV absorber, and a cyanoacrylate-based UV absorber are exemplified. These may be used alone or in combination of two or more. Suitable commercially available ultraviolet absorbers include, for example, Sumisorb (registered trademark) 340 manufactured by Sumika Chemtex Co., Ltd., ADK STAB (registered trademark) LA-31 manufactured by ADEKA, and BASF Japan Co., Ltd. Tinuvin (registered trademark) 1577 and the like. The content of the ultraviolet absorber is preferably from 1 phr to 10 phr, more preferably from 3 phr to 6 phr, based on the mass of the transparent resin film in the present invention.

(Whitening agent)
The transparent resin film in the present invention may further contain a whitening agent. The whitening agent can be added to adjust the tint when, for example, an additive other than the whitening agent is added. Examples of the whitening agent include a monoazo dye, a triarylmethane dye, a phthalocyanine dye, and an anthraquinone dye. Of these, anthraquinone dyes are preferred. Suitable commercially available brighteners include, for example, Macrolex (registered trademark) Violet B (manufactured by LANXESS), Sumiplast (registered trademark) Violet B (manufactured by Sumika Chemtex), and dialyzin (manufactured by Mitsubishi Chemical Corporation). (Registered trademark) Blue G and the like. These may be used alone or in combination of two or more. When a whitening agent is contained, its content is preferably 1 to 50 ppm, more preferably 1 to 45 ppm, still more preferably 3 to 40 ppm, and still more preferably 5 to 5 ppm based on the weight of the transparent resin film in the present invention. 35 ppm.

  The use of the transparent resin film in the present invention is not particularly limited, and may be used for various uses. The transparent resin film may be a single layer as described above, may be a laminate, may be used as it is, or may be used as a laminate with another film May be. Since the transparent resin film has excellent surface quality, it is useful as a transparent resin film in an image display device or the like.

  The transparent resin film in the present invention is useful as a front plate of an image display device, particularly, a front plate (window film) of a flexible display. The flexible display has, for example, a flexible functional layer, and the above-mentioned polyimide-based film which is stacked on the flexible functional layer and functions as a front plate. That is, the front panel of the flexible display is arranged on the viewing side above the flexible functional layer. This front plate has a function of protecting the flexible functional layer.

[Method for producing transparent resin film]
Although the transparent resin film in the present invention is not particularly limited, for example, the following steps:
(A) a step of preparing a liquid containing the resin and the filler (hereinafter sometimes referred to as varnish) (varnish preparation step);
(B) a step of applying a varnish to a substrate to form a coating film (coating step), and (c) a step of drying the applied liquid (coating film) to form a transparent resin film (transparent resin) Film forming process)
Can be produced.

  In the varnish preparation step, the varnish is prepared by dissolving the resin in a solvent, adding the filler and other additives as necessary, and mixing with stirring. When silica is used as the filler, a silica sol obtained by substituting a dispersion of a silica sol containing silica with a solvent capable of dissolving the resin, for example, a solvent used for preparing the following varnish may be added to the resin.

  The solvent used for preparing the varnish is not particularly limited as long as the solvent can dissolve the resin. Examples of such a solvent include amide solvents such as N, N-dimethylacetamide (DMAc) and N, N-dimethylformamide; lactone solvents such as γ-butyrolactone (GBL) and γ-valerolactone; dimethyl sulfone, dimethyl sulfoxide , Sulfolane and the like; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations thereof. Of these, amide solvents or lactone solvents are preferred. These solvents can be used alone or in combination of two or more. Further, the varnish may include water, an alcohol solvent, a ketone solvent, an acyclic ester solvent, an ether solvent, and the like. The solid content concentration of the varnish is preferably 1 to 25% by mass, more preferably 5 to 20% by mass.

  In the coating step, a varnish is coated on the substrate by a known coating method to form a coating film. Known coating methods include, for example, roll coating methods such as wire bar coating method, reverse coating, gravure coating, die coating method, comma coating method, lip coating method, screen coating method, fountain coating method, spraying method, salivation molding method, and the like. Is mentioned.

In the transparent resin film forming step, a long strip-shaped transparent resin film can be formed by drying and peeling the coating film from the substrate. After peeling, a heat treatment step of drying the transparent resin film may be further performed. The heat treatment of the coating film can be usually performed at a temperature of 50 to 350 ° C. If necessary, the coating film may be dried under an inert atmosphere or under reduced pressure.
In the heat treatment, while gripping both ends of the long strip-shaped transparent resin film, while transporting the gripped film, the width of the gripped film as a predetermined distance, for example, while transporting in a dryer, heat treatment Do. At this time, the ratio of the width of the film after heat treatment (excluding the portion to be gripped) to the width of the film before heat treatment (excluding the portion to be gripped) is 1.1 or less, and By releasing the grip, heat treatment of the transparent resin film can be performed.
The ratio of the width of the film after heat treatment (excluding the portion to be gripped) to the width of the film before heat treatment (excluding the portion to be gripped) (hereinafter, sometimes referred to as a draw ratio) is preferably 0.7 to 1.0. , More preferably 0.7 to 0.98. In addition, since the film is not stretched from the portion where the film is gripped to the edge of the film, it is excluded from the film width when calculating the stretching ratio.
The gripping of the film is performed by using, for example, a plurality of clips at both ends of the film.
The plurality of clips can be fixed to an endless chain of a predetermined length depending on the size of the transport device, and the chain moves at the same speed as the film, and the clips are placed at appropriate positions on the chain. It is installed and grips the transparent resin film before entering the dryer, and the grip is released when leaving the dryer.
A plurality of clips installed at one end of the film, the space between the adjacent clips, that is, the distance of the space between the front clip and the rear clip in the film transport direction, for example, 1 to 50 mm, Preferably, it is set to have a thickness of 3 to 25 mm, more preferably 5 to 10 mm.
In addition, a straight line A perpendicular to the film transport axis is aligned with the center of a grip portion of an arbitrary clip at one end of the film, and an intersection between the straight line A and the other end of the film, and a center of the grip portion of the one end clip. When an angle between the straight line B and the center of the grip portion of the clip closest to the intersection is θ, θ is preferably 2 ° or less, more preferably 1 ° or less, and further preferably 0.5 ° or less. It can be made to be. When θ is in the above range, optical properties such as phase difference on the left and right sides of the film can be made uniform.
When the ratio of the width of the film after the heat treatment (however, not including the grip portion) to the width of the film before the heat treatment (however, not including the grip portion) is within the above range, the film appearance tends to be good. .
Further, instead of the clip, the film may be fixed by a pin.
The amount of the solvent in the film after the heat treatment is preferably 0.001 to 3% by mass, more preferably 0.001 to 2% by mass, and still more preferably 0.001 to 1.5% by mass, based on the mass of the film. And particularly preferably 0.001 to 1.3% by mass. When the amount of the solvent in the film after the heat treatment is in the above range, the appearance of the film tends to be good.
When the heat treatment is completed and the film comes out of the dryer, the film is released from gripping, and is preferably slit immediately at the film end. By performing the slit, by removing from the film cracks that are likely to occur between the gripping portion and the portion that was not gripped at the edge of the film, the film is then transported, and the temperature of the film is reduced. The spread of cracks can be prevented in advance.

  Examples of the substrate include a metal-based endless belt made of SUS, a resin-based long belt-shaped PET film, a PEN film, another polyimide resin or a polyamide resin film, a cycloolefin polymer ( COP) film, acrylic film and the like. Above all, a PET film, a COP film and the like are preferable from the viewpoint of excellent smoothness and heat resistance, and a PET film is more preferable from the viewpoint of adhesion to a transparent resin film and cost.

Protective Film In the present invention, the transparent resin film may be a laminate including the protective film bonded to the transparent resin film. The protective film is bonded to the surface of the transparent resin film on which no support is provided. When winding into a roll of the laminate, if there is a problem with the winding property such as blocking, in addition to the above, a protective film is bonded to the surface of the support opposite to the transparent resin film. Is also good. The protective film bonded to the transparent resin film is a film for temporarily protecting the surface of the transparent resin film, and is not particularly limited as long as it is a peelable film that can protect the surface of the transparent resin film. For example, polyester-based resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyethylene, polyolefin-based resin films such as polypropylene film, acrylic-based resin films, and the like; polyolefin-based resin films, polyethylene terephthalate-based resin films, It is preferable to be selected from the group consisting of acrylic resin films. When protective films are stuck on both surfaces of the laminate, the protective films on each surface may be the same or different.

  The thickness of the protective film is not particularly limited, but is usually 10 to 100 μm, preferably 10 to 80 μm. When a protective film is stuck on both sides of the laminate, the thickness of the protective film on each side may be the same or different.

Laminated film roll In the present invention, a laminate in which the above-mentioned laminated body (support, transparent resin film and, if necessary, protective film) is wound around a core in a roll shape is referred to as a laminated film roll. The laminated film roll is often stored once in the form of a film roll because of space and other restrictions in continuous production, and the laminated film roll is one of them.

  Examples of the material constituting the core of the laminated film roll include polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyester resin, epoxy resin, phenol resin, melamine resin, silicon resin, polyurethane resin, polycarbonate resin, ABS resin, and the like. Metal such as aluminum; fiber-reinforced plastic (FRP: a composite material in which fibers such as glass fibers are contained in plastic to improve strength), and the like. The core has a cylindrical or columnar shape and a diameter of, for example, 80 to 170 mm. The diameter of the film roll (the diameter after winding) is not particularly limited, but is usually 200 to 800 mm.

  Moreover, after laminating a protective film to a transparent resin film, it can be slit to a desired width.

  Hereinafter, the effects of the present invention will be made clearer by examples. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications without changing the gist thereof.

(Weight average molecular weight)
Gel Permeation Chromatography (GPC) Measurement (1) Pretreatment Method A sample was dissolved in γ-butyrolactone (GBL) to make a 20% by mass solution, and then diluted 100-fold with a DMF eluent, and a 0.45 μm membrane filter was used. The filtrate was used as a measurement solution.
(2) Measurement condition column: TSKgel SuperAWM-H × 2 + SuperAW2500 × 1 (6.0 mm ID × 150 mm × 3)
Eluent: DMF (10 mmol / L lithium bromide added)
Flow rate: 0.6 mL / min Detector: RI detector Column temperature: 40 ° C
Injection volume: 20 μL
Molecular weight standard: Standard polystyrene

<Measurement of imidation ratio>
The imidation ratio of the polyimide resin and the polyimide resin used in Examples and Comparative Examples was measured by ¹ H-NMR, and calculated using a signal derived from the partial structure shown in Formula (XXX). The method of calculating the imidation ratio from the measurement conditions and the obtained results is as follows.

(NMR measurement conditions)
Measurement device: Bruker 600MHz NMR device AVANCE600
Sample temperature: 303K
Measurement method: ¹ H-NMR, HSQC

(Method of calculating imidation ratio of polyimide resin)
In a ¹ H-NMR spectrum obtained using a solution containing a polyimide resin as a measurement sample, the integral value of the signal derived from the proton (A) in the formula (XXX) is represented by Int _A and the integral value of the signal derived from the proton (B). The value was Int _B. From these values, the imidation ratio (%) was determined by the following formula (NMR-1).

<Measurement of total light transmittance (Tt)>
The total light transmittance of the transparent resin film was measured by a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd. in accordance with JIS K 7105: 1981. Table 3 shows the results.

<Measurement of Haze>
The haze of the transparent resin film was measured by a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd. in accordance with JIS K 7105: 1981. Table 3 shows the results.

<Measurement of Yellowness (YI)>
The yellow index (yellowness: YI value) of the transparent resin film was measured by an ultraviolet-visible-near-infrared spectrophotometer V-670 manufactured by JASCO Corporation. After the background measurement was performed in the absence of the sample, the transparent resin film was set on a sample holder, and the transmittance for light having a wavelength of 300 to 800 nm was measured to determine the tristimulus values (X, Y, Z). The YI value was calculated based on the following equation.
YI value = 100 × (1.2769X−1.0592Z) / Y
Table 3 shows the results.

<Measurement of residual solvent amount>
Using TG-DTA (EXSTAR6000 TG / DTA6300 manufactured by SII Corporation), the transparent resin films obtained in Examples 1 and 2 and Comparative Examples and 2 were heated from 30 ° C. to 120 ° C., and heated at 120 ° C. for 5 hours. Then, the temperature was raised to 400 ° C. at a rate of 5 ° C./min. The ratio of the weight loss of the film from 120 ° C. to 250 ° C. to the weight of the film at 120 ° C. was calculated as the content of the solvent (referred to as the residual solvent amount). Table 3 shows the results.

<Crack>
The film was visually checked at a position where the film was separated from the clip while the film was flowing 50 m, and the presence or absence of cracks was checked. Table 2 shows the results.

<Appearance>
At a position where the film was separated from the clip, the film was visually checked while the film was flowing 50 m, and it was visually checked whether the film was broken or whether there was a corrugation like a galvanized iron (a galvanized iron-like defect). Table 2 shows the results.

<Production Example 1: Production of polyimide resin (1)>
A separable flask equipped with a silica gel tube, a stirrer, and a thermometer, and an oil bath were prepared. In this flask, 75.6 g of 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 2,2′-bis (trifluoromethyl) -4,4′-diaminodiphenyl (TFMB) 54.5 g were charged. While stirring this at 400 rpm, 530 g of N, N-dimethylacetamide (DMAc) was added, and stirring was continued until the contents of the flask became a homogeneous solution. Subsequently, stirring was continued for another 20 hours while adjusting the temperature in the container to be in the range of 20 to 30 ° C. using an oil bath to cause a reaction to generate a polyamic acid. After 30 minutes, the stirring speed was changed to 100 rpm. After stirring for 20 hours, the temperature of the reaction system was returned to room temperature, and 650 g of DMAc was added to adjust the polymer concentration to 10% by mass. Further, 32.3 g of pyridine and 41.7 g of acetic anhydride were added, and the mixture was stirred at room temperature for 10.5 hours to perform imidization. The polyimide varnish was taken out of the reaction vessel. The obtained polyimide varnish was dropped into methanol for reprecipitation, and the obtained powder was heated and dried to remove the solvent, thereby obtaining a polyimide resin (1) as a solid content. GPC measurement was performed on the obtained polyimide resin (1), and as a result, the weight average molecular weight (Mw) was 365,000. The imidation ratio of the polyimide was 99.0%.

<Production Example 2: Production of polyimide resin (2))
Under a nitrogen gas atmosphere, 45 g (140.52 mmol) of TFMB and 768.55 g of DMAc were added to a 1 L separable flask equipped with a stirring blade, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 18.92 g (42.58 mmol) of 6FDA was added to the flask, and the mixture was stirred at room temperature for 3 hours. Thereafter, 4.19 g (14.19 mmol) of 4,4′-oxybis (benzoyl chloride) (OBBC) and 17.29 g (85.16 mmol) of terephthaloyl chloride (TPC) were added to the flask, and the mixture was stirred at room temperature for 1 hour. did. Next, 4.63 g (49.68 mmol) of 4-methylpyridine and 13.04 g (127.75 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath. The mixture was further stirred for 3.5 hours to obtain a reaction solution.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C. to obtain a polyimide resin (2). The weight average molecular weight (Mw) of the polyimide resin (2) was 455,000. The imidation ratio of the polyimide was 98.9%.

<Production Example 3: Production of dispersion liquid 1>
The methanol-dispersed organically treated silica (particle size: 27 nm measured by the BET method) was replaced with γ-butyrolactone (GBL) to obtain a GBL-dispersed organically treated silica (solid content: 30.3%). This dispersion is referred to as Dispersion 1.

<Production Example 4: Production of varnish (1)>
Varnish 1 was prepared by dissolving a polymer in a solvent having a composition shown in Table 1, and having a solid content calculated from the charged amount of 15.5% and a viscosity at 25 ° C of 36,500. Obtained.

<Production Example 5: Production of varnish (2)>
Varnish 2 was mixed with GBL at room temperature such that the composition ratio of the polymer and the filler was 60:40, and Sumisorb 340 (UVA) and Sumiplast Violet B (BA) were added to the total mass of the polymer and silica. 5.7 phr or 35 ppm was added and stirred until uniform. A varnish (2) having a solid content of 10.3% and a viscosity at 25 ° C of 38,500 was obtained.

<Production Example 6: Production of raw material film (1)>
The varnish (1) was formed by salivation molding on a PET (polyethylene terephthalate) film (“Cosmoshine (registered trademark) A4100” manufactured by Toyobo Co., Ltd., film thickness 188 μm, film thickness distribution ± 2 μm). At this time, the linear velocity is 0.4 m / min. After heating at 70 ° C. for 8 minutes, heating at 100 ° C. for 10 minutes, then heating at 90 ° C. for 8 minutes, and finally heating at 80 ° C. for 8 minutes. The coating was dried under the conditions. Thereafter, the coating film was peeled off from the PET film to obtain a raw material film 1 having a thickness of 86 μm and a width of 700 mm. The mass reduction rate M of the raw material film 1 was 9.6%.

<Production Example 7: Production of raw material film (2)>
The varnish (2) was formed into a coating by salivation molding on a PET (polyethylene terephthalate) film (Toyobo Co., Ltd. “Cosmoshine (registered trademark) A4100”, film thickness 188 μm, film thickness distribution ± 2 μm). At this time, the linear velocity was 0.3 m / min. The coating was dried under the conditions of heating at 80 ° C. for 10 minutes, heating at 100 ° C. for 10 minutes, then heating at 90 ° C. for 10 minutes, and finally heating at 80 ° C. for 10 minutes. Thereafter, the coating film was peeled off from the PET film to obtain a raw material film 2 having a thickness of 58 μm and a width of 700 mm. The mass reduction rate M of the raw material film 2 was 9.2%.

<Example 1>
The solvent was removed using a tenter-type drier (1 to 6 chamber configuration) using a clip as a holding tool with the raw material film 1 obtained in Production Example 6 to obtain a polyimide film 1 having a thickness of 79 μm. The temperature in the dryer was set to 200 ° C., the clip grip width was 25 mm, the film transport speed was 1.0 m / min, and the ratio of the film width at the dryer outlet to the film width at the dryer inlet (distance between clips) was 1.0. The wind speed in each room of the tenter dryer was adjusted to 13.5 m / sec in one room, 13 m / sec in two rooms, and 11 m / sec in three to six rooms. After the film was separated from the clip, the clip portion was slit, a PET-based protective film was stuck to the film, and the film was wound around a 6-inch ABS core to obtain a roll film. Table 3 shows the optical characteristics and the residual solvent amount of the obtained film.

<Example 2>
A polyimide film 2 having a thickness of 49 μm was obtained in the same manner as in Example 1 except that the raw material film was changed to the raw material film (2) and the stretching ratio was changed to 0.98. Table 3 shows the optical characteristics and the residual solvent amount of the obtained film.

<Example 3>
A polyimide film 3 having a thickness of 78 μm was obtained in the same manner as in Example 1 except that the ratio of the film width at the dryer inlet (distance between clips) to the film width at the dryer outlet was adjusted to be 1.02. . Table 3 shows the optical characteristics and the residual solvent amount of the obtained film.

<Example 4>
A polyimide film 4 having a thickness of 49 μm was obtained in the same manner as in Example 2 except that the ratio of the film width at the dryer inlet (distance between clips) and the film width at the dryer outlet was adjusted to 0.96. . Table 3 shows the optical characteristics and the residual solvent amount of the obtained film.

<Comparative Example 1>
A polyimide film 5 having a thickness of 48 μm was obtained in the same manner as in Example 2, except that the stretching ratio was changed to 1.3. Table 3 shows the optical characteristics and the residual solvent amount of the obtained film.

<Comparative Example 2>
A polyimide film 6 having a thickness of 50 μm was obtained in the same manner as in Example 2 except that the stretching ratio was changed to 0.8. Table 3 shows the optical characteristics and the residual solvent amount of the obtained film.

(A) Side view, (b) Top view, (1) 1 room, (2) 2 rooms, (3) 3 rooms, (4) 4 rooms, (5) 5 rooms, (6) 6 rooms

Claims (12)

  A step of gripping both ends of a long strip-shaped transparent resin film containing at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, a step of transporting the gripped film, The width of the film is a predetermined distance, the resin film is subjected to heat treatment in a dryer, the ratio of the width of the film after heat treatment to the width of the film before heat treatment is set to 1.1 or less, and the drying machine was left. A method for producing a transparent resin film, comprising a step of releasing gripping of the resin film.   The method according to claim 1, wherein a ratio of a width of the film after the heat treatment to a width of the film before the heat treatment is 0.7 to 1.0.   3. The method according to claim 1, wherein the grip is performed by a plurality of clips.   4. The manufacturing method according to claim 3, wherein the driving device to which the clip is attached moves at the same speed as the film transport speed.   The manufacturing method according to claim 4, wherein the driving of the driving device is performed by a chain.   The manufacturing method according to any one of claims 3 to 5, wherein a space between adjacent clips is 1 to 20 mm.   When a straight line perpendicular to the film transport axis is aligned with the center of the grip portion of an arbitrary clip at one end of the film, the intersection between the straight line and the other end of the film and the center of the grip portion of the clip closest to the intersection point The method according to any one of claims 3 to 6, wherein the distance is 3 mm or less.   The production method according to any one of claims 1 to 7, wherein the content of the organic solvent contained in the resin film after the heat treatment is 0.001 to 3% by mass based on the mass of the resin film.   The method according to any one of claims 1 to 8, further comprising a step of slitting both ends of the film after releasing the grip of the film.   The method according to claim 9, further comprising a step of laminating a protective film on the resin film after slitting the film.   The production method according to claim 10, further comprising a step of slitting the resin film to which the protective film is bonded after bonding the protective film.   The method according to claim 10 or 11, further comprising a step of winding the resin film around a roll after laminating the protective film.

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