JP2020001380A - Method for producing transparent resin film - Google Patents

Abstract

To provide a method for producing a transparent resin film which has good quality even when subjected to heat treatment, and contains at least one resin selected from the group consisting of a polyimide-based resin and a polyamide-based resin.SOLUTION: A method for producing a transparent resin film is a film production method of subjecting a transparent resin film to heat treatment while conveying the transparent resin film that contains a resin and an organic solvent and has a long strip shape in a tenter type drying machine each having a clip chain group including a plurality of clip chains on both of ends of the transparent resin film, when a member having a holding part holding an end of the transparent resin film, a driven metal chain part driven by a metal sprocket, and a metal-made bearing part changing a position of the resin film along the metal-made chain is used as the clip chains. The method lubricates a contact part of the metal components using lubricant oil having a kinematic viscosity at 40°C of 100 mm/s or more and 800 mm/s or less.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, a heat treatment may be performed using a tenter-type drying apparatus.

Incidentally, at the time of such heat treatment, lubricating oil is sometimes used in order to reduce friction between metal parts used in a dryer (for example, Patent Document 1).
The invention described in Patent Document 1 discloses that a polyalkyl ether compound is used as a lubricating oil that does not undergo hydrolysis, has excellent thermal stability, and has a high affinity for a resin film. However, the working temperature is not specifically disclosed in the examples.

JP 2014-137123 A

  The present invention has been proposed in view of such circumstances, and has at least one resin selected from the group consisting of a polyimide resin and a polyamide resin having good quality even after heat treatment. An object of the present invention is to provide a method for manufacturing a transparent resin film.

That is, the present invention provides the following.
[1] A long strip containing at least one resin selected from the group consisting of a polyimide resin and a polyamide resin and an organic solvent in an amount of 0.1 to 30% by mass based on the mass of the transparent resin film. Transparent resin film,
It has a resin film gripping part for gripping the end of the transparent resin film, a driving metal chain part driven by a metal sprocket, and a metal bearing part for changing the position of the resin film gripping part along the metal rail. When the member is a clip chain, in a tenter type dryer having a clip chain group consisting of a plurality of clip chains corresponding to both ends of the transparent resin film, while transporting the transparent resin film, a heat-treated film A manufacturing method,
A method for producing a transparent resin film, wherein a lubricating oil having a kinematic viscosity at 40 ° C. of 100 mm ² / s or more and 800 mm ² / s or less is lubricated at a contact portion of the metal parts.
[2] The production method according to [1], wherein the kinematic viscosity is not less than 100 mm ² / s and less than 800 mm ² .
[3] The production method according to [1] or [2], wherein the kinematic viscosity is 400 mm ² / s or more and 500 mm ² or less.
[4] The method according to any one of [1] to [3], wherein the temperature of the heat treatment is 50 to 350 ° C.
[5] The production method according to any one of [1] to [4], wherein the transport speed of the transparent resin film is 0.1 to 15 m / min.
[6] Irradiate the resin film surface with light at an angle of 20 to 70 ° to lay down, visually check the resin film surface from an angle of 90 ° to specify a stained portion, and perform IR measurement of the stained portion. And a resin film in which the number of detected lubricating oils is 0 / m ² or 1 to 5 / m ² .
[7] A flexible display device comprising the resin film according to [6].
[8] The flexible display device according to [7], further including a touch sensor.
[9] The flexible display device according to [7] or [8], further including a polarizing plate.

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

1 shows an example of a heat treatment furnace for producing a transparent resin film according to the present invention. The film is transported from left to right on the paper. (A) shows the side view of the furnace, and the center line shows the situation where the film is conveyed. (B) shows a top view of the furnace, and a square in the center shows a film to be conveyed.

  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 provides a long belt-like shape comprising at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, and 0.1 to 30% by mass of an organic solvent based on the mass of the transparent resin film. Transparent resin film,
It has a resin film gripping part for gripping the end of the transparent resin film, a driving metal chain part driven by a metal sprocket, and a metal bearing part for changing the position of the resin film gripping part along the metal rail. When the member is a clip chain, in a tenter type dryer having a clip chain group consisting of a plurality of clip chains corresponding to both ends of the transparent resin film, while transporting the transparent resin film, a heat-treated film A manufacturing method,
Provided is a method for producing a transparent resin film, in which a contact portion between these metal parts is lubricated with a lubricating oil having a kinematic viscosity at 40 ° C. of 100 mm ² / s to 800 mm ² / s.

[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 or para position with respect to each of the rings.

  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, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 9 , 9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene And aromatic diamines having two or more aromatic rings such as 9,9-bis (4-amino-3-chlorophenyl) fluorene and 9,9-bis (4-amino-3-fluorophenyl) fluorene. . 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 performed 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 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, and still more preferably 350,000 or more, and preferably 600 or more. 5,000 or less, more preferably 500,000 or less, and still more preferably 450,000 or less. 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 resin or the polyamide 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 resin or the polyamide 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 tends to be easy.

  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. In addition, 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 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass or more, based on the total mass of the transparent resin film. The content of the silica particles is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 45% by mass or less, based on the total mass of the transparent resin film. 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 weight 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 Co., Ltd., and Diaresin manufactured by Mitsubishi Chemical Corporation. (Registered trademark) Blue G and the like. These may be used alone or in combination of two or more. The content of the whitening agent is preferably 5 ppm or more and 40 ppm or less based on the mass of the transparent resin film in the present invention.

  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 performed at a temperature of usually 50 to 350 ° C, preferably 100 to 300 ° 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 heat treatment of the transparent resin film is performed by setting the 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 releasing the grip of the resin film coming out of the dryer. be able to.
The holding of the film is performed, for example, by using a plurality of clips. Also, pins can be used instead of clips.
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.

The clip and the endless chain are usually made of metal, and a lubricating oil is used at a portion where the metal parts come into contact with each other to reduce friction and the like. The kinematic viscosity of the lubricating oil at 40 ° C. is usually 100 mm ² / s or more and 800 mm ² / s or less, preferably 100 mm ² / s or more and less than 800 mm ² / s, more preferably 100 mm ² / s or more and 700 mm ² / s or less. More preferably, 100 mm ² / s or more and less than 700 mm ² / s, still more preferably 150 mm ² / s or more and 600 mm ² / s or less, particularly preferably 150 mm ² / s or more and less than 600 mm ² / s, and particularly preferably 200 mm ² / s. s or more and 500 mm ² / s or less, particularly preferably 200 mm ² / s or more and less than 500 mm ² / s.
As the lubricating oil, for example, Valierta (registered trademark) J400V (manufactured by NOK Kuruba Co., Ltd.), Daphne (registered trademark) oil CO 100, 150, 220, 260 (manufactured by Idemitsu Kosan Co., Ltd.), S-3101, S-3103, S-3105, S-3230 (manufactured by MORESCO), Unistar (registered trademark) H-481D, HR-170R, HR-200, H-609BR, C-3373A, C-400B, C- 6910BE, TOE-500 (manufactured by NOF Corporation) and the like.

The plurality of clips installed at one end of the film are installed such that the space between adjacent clips is, for example, 1 to 50 mm, preferably 3 to 25 mm, and more preferably 5 to 10 mm.
Also, 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 of 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. Is preferably 3 mm or less, more preferably 2 mm or less, and still more preferably 1 mm or less. When the distance is within the above range, for example, the optical properties of the left and right sides of the film can be made uniform.

  The transport speed of the film is preferably 0.1 to 15 m / min, more preferably 0.1 to 10 m / min. When the transport speed is in the above range, the quality of the obtained film, for example, in-plane uniformity can be improved.

  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.

  The raw material film has a weight loss rate M from 120 ° C. to 250 ° C. determined by thermogravimetry-differential calorimetry (hereinafter sometimes referred to as “TG-DTA measurement”), preferably about 1 to 40%, more preferably. It is preferable that a part of the solvent is removed from the varnish so that the varnish is 3 to 20%, more preferably 5 to 15%, particularly preferably 5 to 12%. The weight loss rate M of the raw material film can be measured by the following method using a commercially available TG-DTA measuring device. As a TG-DTA measuring device, TG / DTA6300 manufactured by Hitachi High-Tech Science Corp. can be used.

First, about 20 mg of a sample was obtained from the raw material film, the sample was heated from room temperature to 120 ° C. at a rate of 10 ° C./min, kept at 120 ° C. for 5 minutes, and then 10 ° C./min to 400 ° C. The weight change of the sample is measured while heating at a temperature increasing rate. Next, from the result of the TG-DTA measurement, the weight loss rate M (%) from 120 ° C. to 250 ° C. may be calculated by the following equation. In the following formula, W ₀ indicates the weight of the sample after holding at 120 ° C. for 5 minutes, and W ₁ indicates the weight of the sample at 250 ° C.
M (%) = 100− (W ₁ / W ₀ ) × 100

  When the weight loss rate M of the raw material film is somewhat large, when the raw material film is wound up as a laminate with a substrate or a surface protection film, deformation such as bending of the laminate is suppressed, and the winding property of the laminate is reduced. Tends to improve.

  When the weight loss rate M of the raw material film is small to some extent, when the raw material film is wound up as a laminate with the base material or the surface protection film, the raw material film tends to be less likely to stick to the base material or the surface protection film. Therefore, the laminate can be easily unwound from the roll while maintaining the uniform transparency of the raw material film.

<Protective film>
In the present invention, the transparent resin film may be a laminate including a 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. In the form of the laminate film roll, since the laminate is tightly wound, the substance causing white turbidity on the support is easily transferred onto the transparent resin film. However, when the support having a predetermined water contact angle of the present invention is used, the cloudy substance from the support is difficult to be transferred to the transparent resin film, and even when it is wound with the laminate film roll, cloudy occurs. Hateful.

  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 after winding the film roll 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.

<Flexible image display device>
The present invention includes a flexible display device including the optical film. The optical film of the present invention is preferably used as a front plate in a flexible image display device, and the front plate may be referred to as a window film. The flexible image display device includes a laminate for a flexible image display device and an organic EL display panel. The laminate for a flexible image display device is arranged on the viewing side with respect to the organic EL display panel, and is configured to be bendable. ing. The laminate for a flexible image display device may further include a polarizing plate and a touch sensor, and the stacking order thereof is arbitrary, but from the viewing side, a window film, a polarizing plate, a touch sensor or a window film, and a touch panel. It is preferable that the sensor and the polarizing plate are stacked in this order. The presence of the polarizing plate on the viewing side with respect to the touch sensor is preferable because the pattern of the touch sensor is hardly viewed and the visibility of the display image is improved. Each member can be laminated using an adhesive, a pressure-sensitive adhesive or the like. In addition, a light-shielding pattern formed on at least one surface of any one of the window film, the polarizing plate, and the touch sensor can be provided.

[Polarizer]
As described above, the flexible display device of the present invention includes a polarizing plate, preferably a circular polarizing plate. The circularly polarizing plate is a functional layer having a function of transmitting only right or left circularly polarized light components by laminating a λ / 4 retardation plate on a linearly polarizing plate. For example, by converting external light into right-handed circularly polarized light, the external light reflected by the organic EL panel and turned into left-handed circularly polarized light is blocked, and only the luminescent component of the organic EL is transmitted, thereby suppressing the influence of the reflected light and thereby reducing the image. Used to make it easier to see. In order to achieve the circular polarization function, the absorption axis of the linear polarizing plate and the slow axis of the λ / 4 retardation plate need to be 45 ° in theory, but practically 45 ± 10 °. The linear polarizing plate and the λ / 4 retardation plate do not necessarily need to be laminated adjacent to each other, as long as the relationship between the absorption axis and the slow axis satisfies the above range. It is preferable to achieve perfect circularly polarized light at all wavelengths, but this is not always necessary in practical use. Therefore, the circularly polarizing plate in the present invention includes an elliptically polarizing plate. It is also preferable to further laminate a λ / 4 retardation film on the viewing side of the linear polarizing plate and to make the outgoing light circularly polarized so as to improve the visibility in a state where polarized sunglasses are worn.

  The linear polarizing plate is a functional layer having a function of passing light vibrating in the transmission axis direction but blocking polarization of a vibration component perpendicular to the light. The linear polarizing plate may be configured to include a linear polarizer alone or a linear polarizer and a protective film attached to at least one surface thereof. The thickness of the linear polarizing plate may be 200 μm or less, and preferably 0.5 to 100 μm. When the thickness of the linearly polarizing plate is in the above range, the flexibility of the linearly polarizing plate tends to hardly decrease.

  The linear polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) -based film. A dichroic dye such as iodine is adsorbed on a PVA-based film oriented by stretching or stretched in a state of being adsorbed on PVA, whereby the dichroic dye is oriented to exhibit polarizing performance. In the production of the film-type polarizer, other steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be included. The stretching and dyeing steps may be performed on the PVA-based film alone, or may be performed in a state of being laminated with another film such as polyethylene terephthalate. The thickness of the PVA-based film used is preferably 10 to 100 μm, and the stretching ratio is preferably 2 to 10 times.

Further, another example of the polarizer includes a liquid crystal application type polarizer formed by applying a liquid crystal polarizing composition. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. The liquid crystal compound only needs to have a property of exhibiting a liquid crystal state. In particular, it is preferable that the compound has a high-order alignment state such as a smectic phase because high polarization performance can be exhibited. Further, the liquid crystal compound preferably has a polymerizable functional group.
The dichroic dye compound is a dye that exhibits dichroism when aligned with the liquid crystal compound, and may have a polymerizable functional group, and the dichroic dye itself has liquid crystallinity. May be.

  Any of the compounds contained in the liquid crystal polarizing composition has a polymerizable functional group. The liquid crystal polarizing composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like.

  The liquid crystal polarizing layer is manufactured by applying a liquid crystal polarizing composition on an alignment film to form a liquid crystal polarizing layer. The liquid crystal polarizing layer can be formed to be thinner than the film type polarizer, and the thickness is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

  The alignment film is manufactured, for example, by applying an alignment film forming composition on a substrate and imparting the alignment by rubbing, polarized light irradiation, or the like. The composition for forming an alignment film includes an alignment agent, and may further include a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. Examples of the aligning agent include polyvinyl alcohols, polyacrylates, polyamic acids, and polyimides. In the case of using an aligning agent that imparts an orientation by polarized light irradiation, it is preferable to use an aligning agent containing a cinnamate group. The weight average molecular weight of the polymer used as the alignment agent is, for example, about 10,000 to 1,000,000. The thickness of the alignment film is preferably 5 to 10,000 nm, and more preferably 10 to 500 nm from the viewpoint that the alignment regulating force is sufficiently exhibited.

  The liquid crystal polarizing layer can be peeled off from the substrate and transferred to be laminated, or the substrate can be laminated as it is. It is also preferable that the base material plays a role as a transparent base material for a protective film, a retardation plate, and a window film.

  The protective film only needs to be a transparent polymer film, and the same materials and additives as those used for the transparent substrate of the window film can be used. Further, a coating type protective film obtained by applying and curing a cationically curable composition such as an epoxy resin or a radically curable composition such as an acrylate may be used. The protective film may be, if necessary, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, and an antioxidant. , A lubricant, a solvent, and the like. The thickness of the protective film is preferably 200 μm or less, more preferably 1 to 100 μm. When the thickness of the protective film is in the above range, the flexibility of the film tends to hardly decrease.

  The λ / 4 retardation plate is a film that gives a λ / 4 phase difference in a direction (in-plane direction of the film) orthogonal to the traveling direction of incident light. The λ / 4 retardation plate may be a stretched retardation plate manufactured by stretching a polymer film such as a cellulose film, an olefin film, and a polycarbonate film. If necessary, the λ / 4 retardation plate may include a retardation adjuster, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or a dye, a fluorescent brightener, a dispersant, a heat stabilizer, and a light stabilizer. Agents, antistatic agents, antioxidants, lubricants, solvents and the like.

  The thickness of the stretch type retardation plate is preferably 200 μm or less, more preferably 1 to 100 μm. When the thickness of the stretched retardation film is in the above range, the flexibility of the stretched retardation film tends to be hardly reduced.

  Another example of the λ / 4 retardation plate is a liquid crystal-coated retardation plate formed by applying a liquid crystal composition.

  The liquid crystal composition contains a liquid crystal compound exhibiting a liquid crystal state such as nematic, cholesteric, or smectic. The liquid crystalline compound has a polymerizable functional group.

  The liquid crystal composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like.

  The liquid crystal coating type retardation plate can be manufactured by applying and curing a liquid crystal composition on a base to form a liquid crystal retardation layer, similarly to the liquid crystal polarizing layer. The liquid crystal coating type retarder can be formed to be thinner than the stretch type retarder. The thickness of the liquid crystal polarizing layer is preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

  The liquid crystal coating type retardation plate can be peeled off from the substrate and transferred and laminated, or the substrate can be laminated as it is. It is also preferable that the base material plays a role as a transparent base material for a protective film, a retardation plate, and a window film.

  In general, there are many materials exhibiting a large birefringence at a short wavelength and a small birefringence at a long wavelength. In this case, a phase difference of λ / 4 cannot be achieved in the entire visible light region. Therefore, the in-plane phase difference is preferably 100 to λ / 4 near 560 nm where visibility is high. It is designed to be 180 nm, more preferably 130 to 150 nm. An inverse dispersion λ / 4 retardation plate using a material having a birefringence wavelength dispersion property opposite to that of a normal one is preferable in that visibility is improved. As such a material, for example, a stretch type retarder described in JP-A-2007-232873 and a liquid crystal-coated phase retarder described in JP-A-2010-30979 can be used. .

  As another method, a technique of obtaining a broadband λ / 4 phase difference plate by combining with a λ / 2 phase difference plate is also known (for example, Japanese Patent Application Laid-Open No. 10-90521). The λ / 2 retardation plate is also manufactured by the same material method as the λ / 4 retardation plate. The combination of the stretching type retardation plate and the liquid crystal coating type retardation plate is arbitrary, but both can be reduced in thickness by using the liquid crystal coating type retardation plate.

  There has been known a method of laminating a positive C plate on the circularly polarizing plate in order to enhance the visibility in an oblique direction (for example, JP-A-2014-224837). The positive C plate may be a liquid crystal coating type retardation plate or a stretching type retardation plate. The retardation in the thickness direction of the retardation plate is preferably -200 to -20 nm, more preferably -140 to -40 nm.

[Touch sensor]
As described above, the flexible display device of the present invention preferably includes a touch sensor. The touch sensor is used as an input unit. Examples of the touch sensor include various types such as a resistance film type, a surface acoustic wave type, an infrared type, an electromagnetic induction type, and a capacitance type, and preferably a capacitance type.
The capacitive touch sensor is divided into an active area and a non-active area located outside the active area. The active area is an area corresponding to an area (display unit) where a screen is displayed on the display panel, and is an area where a user's touch is sensed, and the inactive area is an area where the screen is not displayed on the display device (non-display area). Display area). The touch sensor is formed on a substrate having flexible characteristics, a sensing pattern formed on an active region of the substrate, and an inactive region of the substrate, and is connected to an external driving circuit through the sensing pattern and a pad unit. For each sensing line. As the substrate having the flexible characteristics, the same material as the transparent substrate of the window film can be used.

  The sensing pattern may include a first pattern formed in a first direction and a second pattern formed in a second direction. The first pattern and the second pattern are arranged in directions different from each other. The first pattern and the second pattern are formed on the same layer, and must be electrically connected to each other to detect a touched point. The first pattern is a form in which a plurality of unit patterns are connected to each other via a joint, while the second pattern has a structure in which a plurality of unit patterns are separated from each other in an island form. A separate bridge electrode is required to make the connection. A well-known transparent electrode can be applied to the electrode for the connection of the second pattern. As the material of the transparent electrode, for example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), indium gallium zinc oxide (IGZO) , Cadmium tin oxide (CTO), PEDOT (poly (3,4-ethylenedioxythiophene)), carbon nanotube (CNT), graphene, metal wire, and the like, and preferably ITO. These can be used alone or in combination of two or more. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, and chromium. These may be used alone or in combination of two or more. Can be.

  The bridge electrode may be formed on the insulating layer above the sensing pattern via an insulating layer. The bridge electrode is formed on the substrate, and the insulating layer and the sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium or an alloy of two or more of these. it can.

  Since the first and second patterns must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed as a layer covering the entire sensing pattern. In the case of a layer that covers the entire sensing pattern, the bridge electrode can connect the second pattern through a contact hole formed in the insulating layer.

  The touch sensor is induced by a difference in transmittance between a pattern region where a sensing pattern is formed and a non-pattern region where a sensing pattern is not formed, specifically, a difference in refractive index in these regions. As a means for appropriately compensating for the difference in light transmittance, an optical adjustment layer may be further provided between the substrate and the electrode. The optical control layer may include an inorganic insulating material or an organic insulating material. The optical control layer can be formed by coating a photocurable composition containing a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical control layer can be increased by the inorganic particles.

  The photo-curable organic binder includes, for example, a copolymer of each monomer such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer as long as the effects of the present invention are not impaired. be able to. The photocurable organic binder may be, for example, a copolymer containing different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.

  Examples of the inorganic particles include zirconia particles, titania particles, and alumina particles.

  The photocurable composition may further include additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

[Adhesive layer]
Each layer (window film, circular polarizer, touch sensor) forming the laminate for a flexible image display device and a film member (linear polarizer, λ / 4 retardation plate, etc.) forming each layer are bonded by an adhesive. Can be. Examples of the adhesive include an aqueous adhesive, an aqueous solvent volatile adhesive, an organic solvent-based, solventless adhesive, a solid adhesive, a solvent volatile adhesive, a moisture-curable adhesive, a heat-curable adhesive, and an anaerobic adhesive. Commonly used adhesives such as curing type, active energy ray curing type adhesive, curing agent mixed type adhesive, hot melt type adhesive, pressure sensitive type adhesive (adhesive), rewetting type adhesive etc. are used. Preferably, an aqueous solvent volatilizing adhesive, an active energy ray-curable adhesive, or a pressure-sensitive adhesive can be used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesive strength and the like, and is preferably 0.01 to 500 μm, and more preferably 0.1 to 300 μm. The laminate for a flexible image display device has a plurality of adhesive layers, but the thicknesses and types thereof may be the same or different.

  As the water-based solvent-evaporable adhesive, a water-soluble polymer such as a polyvinyl alcohol-based polymer, a starch or the like, an ethylene-vinyl acetate-based emulsion, or a styrene-butadiene-based emulsion can be used as a main polymer. In addition to the main polymer and water, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be blended. In the case of bonding with the aqueous solvent volatilizing adhesive, the adhesive can be imparted by injecting the aqueous solvent volatilizing adhesive between the layers to be bonded, bonding the layer to be bonded, and then drying. When the water-based solvent-evaporating adhesive is used, the thickness of the adhesive layer is preferably 0.01 to 10 μm, more preferably 0.1 to 1 μm. When the aqueous solvent-evaporating adhesive is used for a plurality of layers, the thickness and type of each layer may be the same or different.

  The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material that forms an adhesive layer upon irradiation with an active energy ray. The active energy ray-curable composition can contain at least one polymer of the same radical polymerizable compound and cationic polymerizable compound as those contained in the hard coat composition. As the radical polymerizable compound, the same compound as the radical polymerizable compound in the hard coat composition can be used.

  As the cationic polymerizable compound, the same compound as the cationic polymerizable compound in the hard coat composition can be used.

  As the cationically polymerizable compound used in the active energy ray-curable composition, an epoxy compound is particularly preferred. It is also preferable to include a monofunctional compound as a reactive diluent in order to reduce the viscosity of the adhesive composition.

  The active energy ray composition may include a monofunctional compound in order to reduce the viscosity. Examples of the monofunctional compound include an acrylate monomer having one (meth) acryloyl group in one molecule and a compound having one epoxy group or oxetanyl group in one molecule, for example, glycidyl (meth) A) acrylate and the like.

  The active energy ray composition can further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, and these are appropriately selected and used. These polymerization initiators are decomposed by at least one of irradiation with active energy rays and heating to generate radicals or cations to promote radical polymerization and cationic polymerization. In the description of the hard coat composition, an initiator capable of initiating at least one of radical polymerization and cationic polymerization by irradiation with active energy rays can be used.

  The active energy ray-curable composition further comprises an ion scavenger, an antioxidant, a chain transfer agent, an adhesion promoter, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, a defoamer solvent, an additive, and a solvent. Can be included. When the two adhesive layers are bonded by the active energy ray-curable adhesive, the active energy ray-curable composition is applied to one or both of the adhesive layers, and then bonded, and any one of the adhesive layers is bonded. Alternatively, both the layers to be bonded can be bonded by irradiating them with an active energy ray and curing them. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.01 to 20 μm, and more preferably 0.1 to 10 μm. When the active energy ray-curable adhesive is used for forming a plurality of adhesive layers, the thickness and type of each layer may be the same or different.

  The pressure-sensitive adhesive is classified into an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive and the like depending on the main polymer, and any of them can be used. The pressure-sensitive adhesive may contain a crosslinking agent, a silane compound, an ionic compound, a cross-linking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like, in addition to the base polymer. The components constituting the pressure-sensitive adhesive are dissolved and dispersed in a solvent to obtain a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition is dried after being coated on a substrate, thereby forming a pressure-sensitive adhesive layer adhesive layer. You. The pressure-sensitive adhesive layer may be directly formed, or a layer separately formed on a substrate may be transferred. It is also preferable to use a release film to cover the adhesive surface before bonding. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.1 to 500 μm, more preferably 1 to 300 μm. When using a plurality of layers of the pressure-sensitive adhesive, the thickness and type of each layer may be the same or different.

[Shading pattern]
The light shielding pattern can be applied as at least a part of a bezel or a housing of the flexible image display device. The visibility of the image is improved by concealing the wiring arranged on the peripheral portion of the flexible image display device by the light-shielding pattern so that the wiring is difficult to see. The light-shielding pattern may be in the form of a single layer or multiple layers. The color of the light-shielding pattern is not particularly limited, and may be various colors such as black, white, and metal. The light-shielding pattern can be formed of a pigment for realizing a color and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or silicone. These can be used alone or in a mixture of two or more. The light-shielding pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the light-shielding pattern is preferably 1 to 100 μm, more preferably 2 to 50 μm. It is also preferable to provide a shape such as an inclination in the thickness direction of the light shielding pattern.

  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.

<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 of the obtained polyimide resin (1) showed a weight average molecular weight of 365,000. The imidation ratio of the polyimide resin (1) was 99.0%. Similarly, a large amount of the polyimide resin (1) was obtained.

<Measurement of imidation ratio>
The imidation ratio of the polyimide resin obtained above was calculated from the results of ¹ H-NMR measurement, focusing on the signal derived from the partial structure represented by the following formula (Formula XXX). The measurement conditions and calculation method are 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 integrated value of the signal derived from the proton (A) in the above formula (XXX) is represented by Int _A and the signal derived from the proton (B). the integral value was Int _B. From these values, the imidation ratio (%) was determined by the following formula (NMR-1).

<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 of the polyimide resin (2) was 455,000. The imidation ratio of the polyimide resin (2) was 98.9%. Similarly, a large amount of the polyimide resin (2) was obtained.

<Production Example 3: Production of dispersion liquid 1>
The methanol-dispersed organically treated silica (average primary particle diameter measured by the BET method: 27 nm) was replaced with γ-butyrolactone (GBL) to obtain a GBL-dispersed organically treated silica (solid content: 30.3% by mass). 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 at room temperature with a GBL solvent so 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 and stirred until uniform. A varnish (2) having a solid content of 10.3% by mass and a viscosity of 38,500 at 25 ° C. 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 cast on a PET (polyethylene terephthalate) film (“Cosmoshine A4100”, manufactured by Toyobo Co., Ltd., thickness 188 μm, thickness distribution ± 2 μm) to form a coating film. 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: Production of resin film>
The solvent was removed from the raw material film 1 obtained in Production Example 6 using a tenter drier (1 to 6 chamber configuration) using a clip as a gripper, to obtain a 79 μm-thick polyimide film 1. At that time, the temperature in the dryer was set to 200 ° C., the gripping width of the clip was 25 mm, the film transport speed was 1.1 m / min, and the ratio of the film width at the dryer inlet (distance between clips) to the film width at the dryer outlet. Was set to 1.0, and processing was performed on a film transport rail of a tenter by using Varierta J400V manufactured by NOK Cluiba Co., Ltd. as lubricating oil. 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 2 shows the appearance of the film after leaving the tenter type dryer and the residual solvent amount of the obtained polyimide film.

<Kinematic viscosity measurement>
The kinematic viscosity was measured at 40 ° C. according to the method described in JIS Z 8803: 2011.

<Flying distance measurement>
One drop of lubricating oil was dropped five times from a 5 cc dropper five times from a height of 600 mm on a PET film, the distance from the center of the drop point to the center of the droplet where the oil scattered most was measured, and the average distance was calculated. Calculated.

<Lubricant stain on film>
The surface of the obtained film was irradiated with Polarion Light (“PS-X1” manufactured by Polarion) (3,400 lumens) from the flow direction (that is, the vertical direction). At this time, irradiation was performed at an angle of about 20 to 70 ° with respect to the film surface. The direction of visual recognition is almost right above the surface of the resin film to be evaluated (at an angle of 90 ° from the surface of the resin film). The evaluation was performed with human eyes, and the stained portion was specified. IR measurement of the contaminated spot was performed, and 0 / m ² was determined to be good as the detected number of lubricating oils used, and Δ was determined. 1 to 5 / m ² was determined to be slightly good and Δ was determined. was × in determined to be defective or more / m ^2.

<Example 2: Production of resin film>
The raw material film 2 obtained in Production Example 7 was used, the film transport speed was 2.7 m / min, and the ratio of the film width at the dryer inlet (distance between clips) to the film width at the dryer outlet was 0.98. In the same manner as in Example 1 except that the above was performed, a polyamide-imide-based film 1 having a thickness of 49.5 μm was obtained. At this time, Table 2 shows the appearance of the film after leaving the tenter-type dryer and the residual solvent amount of the obtained polyamideimide-based film 1.

<Comparative Example 1: Preparation of resin film>
Except that the lubricating oil was changed to Varierta J100V (manufactured by NOK Cruiba Co., Ltd.), and that the conveying speed was changed to 0.9 m / min, a 49 μm thick raw film 2 was obtained in the same manner as in Example 2. Polyamideimide film 2 was obtained. Table 2 shows the appearance of the film after leaving the tenter-type dryer and the amount of residual solvent in the obtained polyamideimide-based film 2.

<Comparative Example 2: Production of resin film>
A 50 μm thick polyamide-imide film 2 was obtained from the raw material film 2 in the same manner as in Comparative Example 1 except that the lubricating oil was changed to UCON (registered trademark) 50HB-5100 (manufactured by Dow Chemical). At that time, Table 2 shows the appearance of the film after leaving the tenter type dryer and the residual solvent amount of the obtained polyamideimide film 3. Since the viscosity of the lubricating oil was high, the lubricating oil generated heat, the viscosity was reduced, and film contamination was confirmed.

<Example 3: Production of resin film>
A polyamideimide-based film 4 was obtained in the same manner as in Example 2, except that Unistar (registered trademark) H-609BR (manufactured by NOF Corporation) was used as a lubricating oil. At this time, Table 2 shows the appearance of the film after leaving the tenter-type dryer and the residual solvent amount of the obtained polyamideimide-based film 4.

(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 (9)

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, and 0.1 to 30% by mass of an organic solvent with respect to the mass of the transparent resin film. To
It has a resin film gripping part for gripping the end of the transparent resin film, a driving metal chain part driven by a metal sprocket, and a metal bearing part for changing the position of the resin film gripping part along the metal rail. When the member is a clip chain, a method for producing a film that is heat-treated while transporting the transparent resin film in a tenter type dryer having a clip chain group including a plurality of clip chains at both ends of the transparent resin film. And
A method for producing a transparent resin film, wherein a lubricating oil having a kinematic viscosity at 40 ° C. of 100 mm ² / s or more and 800 mm ² / s or less is lubricated at a contact portion of the metal parts. The kinematic viscosity is less than 100 mm ² / s or more 800 mm ^2, The process of claim 1 wherein. The production method according to claim 1, wherein the kinematic viscosity is 400 mm ² / s or more and 500 mm ² or less.   The method according to claim 1, wherein the temperature of the heat treatment is 50 to 350 ° C. 5.   The method according to any one of claims 1 to 4, wherein the transport speed of the transparent resin film is 0.1 to 15 m / min. The resin film surface was irradiated with light at an angle of 20 to 70 ° to lie down, visually observed from an angle of 90 ° from the resin film surface to identify a stained portion, and IR measurement of the stained portion was performed. A resin film in which the number of detected lubricating oils is 0 / m ² or 1 to 5 / m ² .   A flexible display device comprising the resin film according to claim 6.   The flexible display device according to claim 7, further comprising a touch sensor.   The flexible display device according to claim 7, further comprising a polarizing plate.

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