阅读说明：本技术 树脂膜卷的制造方法 (Method for manufacturing resin film roll ) 是由 野殿光纪 永田诚 大松一喜 于 2019-06-20 设计创作，主要内容包括：本发明提供异物附着少的树脂膜卷的制造方法。透明树脂膜与保护膜的树脂膜卷的制造方法,其包括下述工序：从长条带状的基材与透明树脂膜的层叠体中剥离基材的工序,把持透明树脂膜的端部的工序,在以规定的宽度把持透明树脂膜的同时、在加热炉内传送所述透明树脂膜的工序,将透明树脂膜从加热炉传送出的工序,将透明树脂膜的把持解除的工序,使透明树脂膜通过污物清除辊的工序,将透明树脂膜的内部电荷除去的工序,对贴合了保护膜的透明树脂膜进行卷绕的工序。(The invention provides a method for manufacturing a resin film roll with less foreign matter adhesion. A method for manufacturing a resin film roll of a transparent resin film and a protective film, comprising the steps of: the method for manufacturing the transparent resin film includes a step of peeling a substrate from a laminated body of a long strip-shaped substrate and a transparent resin film, a step of holding an end of the transparent resin film, a step of conveying the transparent resin film in a heating furnace while holding the transparent resin film with a predetermined width, a step of conveying the transparent resin film out of the heating furnace, a step of releasing the holding of the transparent resin film, a step of passing the transparent resin film through a stain removing roller, a step of removing internal charges of the transparent resin film, and a step of winding the transparent resin film to which a protective film is bonded.)

1. A method for manufacturing a resin film roll of a transparent resin film and a protective film, comprising the steps of:

a step of peeling the substrate from the laminate of the long strip-shaped substrate and the transparent resin film,

a step of holding an end portion of the transparent resin film,

a step of conveying the transparent resin film in a heating furnace while holding the transparent resin film with a predetermined width,

a step of conveying the transparent resin film from the heating furnace,

a step of releasing the grip of the transparent resin film,

a step of passing the transparent resin film through a stain removing roll,

a step of removing the internal charge of the transparent resin film,

and a step of winding the transparent resin film to which the protective film is attached.

2. The manufacturing method according to claim 1, comprising a step of slitting the transparent resin film.

3. The production method according to claim 1 or 2, comprising a step of bonding a protective film to the transparent resin film.

4. And a transparent resin film on which charged toner is dispersed, wherein when an Image of the toner adhering to the transparent resin film is captured, the obtained Image is converted into 8-bit colors using Image-J of version 1.48, and the number of colors is set to 3 under the set conditions, the proportion of the Image portion which is not charged and has no toner adhering thereto is 60% or more of the measurement area in the set conditions.

Technical Field

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

Background

In the optical film, static electricity is removed by an ionizer in order to avoid mixing of foreign substances due to electrostatic adsorption (see, for example, patent document 1).

In recent years, a transparent resin film has been required for flexible display devices instead of glass. As a material of such a transparent resin film, a material having transparency and mechanical strength such as a polyimide-based resin or a polyamide-based resin is known.

In the production of such a transparent resin film, a varnish that is a precursor of the transparent resin film is continuously applied to a substrate, and an organic solvent contained in the varnish is removed to obtain a laminate of the substrate and the transparent resin film. Then, the substrate is peeled off from the laminate, and the transparent resin film is subjected to a heat treatment for obtaining a desired quality, and in the heat treatment, for example, a tenter type drying apparatus is used in some cases. Here, although the transparent resin film is usually shipped after the protective film is attached before shipment, if dirt or the like adheres to the charged transparent resin film before the protective film is attached, the film attached while maintaining this state will contain dirt, which may cause damage or the like to the transparent resin film.

Therefore, in general, in order to remove the static electricity, for example, a static electricity removing device is used to remove surface charges. However, the present inventors have found, through their studies, that such a conventional static elimination method is insufficient.

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a resin film roll with less adhesion of foreign matters.

Means for solving the problems

Namely, the present invention provides the following.

[1] A method for manufacturing a resin film roll, comprising the steps of:

a step of peeling the substrate from the laminate of the long strip-shaped substrate and the transparent resin film,

a step of holding an end portion of the transparent resin film,

a step of conveying the transparent resin film in a dryer while holding the transparent resin film with a predetermined width,

a step of conveying the transparent resin film from the dryer,

a step of releasing the grip of the transparent resin film,

a step of passing the transparent resin film through a stain removing roll,

a step of removing the internal charge of the transparent resin film,

and a step of winding the transparent resin film.

[2] The production method according to [1], which comprises a step of slitting the transparent resin film.

[3] The production method according to [1] or [2], which comprises a step of bonding a protective film to the transparent resin film.

[4] And a transparent resin film on which charged toner is dispersed, an Image of the toner adhering to the transparent resin film is captured, the obtained Image is converted into an 8-bit color (8bit color) using Image-J of version 1.48, and when the number of colors (number of colors) is set to 3 under the set conditions to obtain an Image, the proportion of the Image having no toner adhering thereto without being charged in the set conditions is 60% or more of the measurement area.

ADVANTAGEOUS EFFECTS OF INVENTION

As described above, according to the manufacturing method of the present invention, a resin film roll with less foreign matter adhesion can be obtained.

Drawings

Fig. 1 shows the film appearance after the toner test. (a) The film appearance of example 2, (b) the film appearance of comparative example 1, and (c) the film appearance of comparative example 2.

FIG. 2 is a view showing an example of the installation position of the static eliminator.

FIG. 3 is a photograph showing the appearance shown in Table 4. D is the appearance of example 1, E is the appearance of comparative example 3, and F is the appearance of comparative example 4.

Fig. 4 is a schematic view of imaging in the evaluation of charging performance.

Description of the reference numerals

1: nano static electricity removing device

2: ionization device

3: transparent resin film

4: camera with a camera module

Detailed Description

The materials, dimensions, and the like described in the following description are examples, and the present invention is not necessarily limited to these examples, and can be carried out with appropriate modifications within a range not changing the gist thereof.

The invention provides a method for manufacturing a resin film roll, which comprises the following steps:

a step of peeling the substrate from the laminate of the long strip-shaped substrate and the transparent resin film,

a step of holding an end portion of the transparent resin film,

a step of conveying the transparent resin film in a dryer while holding the transparent resin film with a predetermined width,

a step of conveying the transparent resin film from the dryer,

a step of releasing the grip of the transparent resin film,

a step of passing the transparent resin film through a stain removing roll,

a step of removing the internal charge of the transparent resin film,

and a step of winding the transparent resin film.

[ polyimide resin, Polyamide resin ]

The transparent resin film of the present invention contains at least 1 resin selected from the group consisting of polyimide-based resins and polyamide-based resins. The polyimide-based resin represents at least 1 polymer selected from the group consisting of 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, sometimes referred to as polyamideimide). The polyamide resin represents a polymer containing a repeating structural unit containing an amide group.

The polyimide resin preferably has a repeating structural unit represented by formula (10). Here, G is a 4-valent organic group, and a is a 2-valent organic group. The polyimide resin may contain 2 or more kinds of repeating structural units represented by the formula (10) different in G and/or A.

The polyimide resin may contain 1 or more selected from the group consisting of repeating structural units represented by formula (11), formula (12), and formula (13) within a range that does not impair various physical properties of the transparent resin film.

In formulas (10) and (11), G and G¹Each independently is a 4-valent organic group, preferably an organic group which may be substituted with a hydrocarbyl group or a fluoro-substituted hydrocarbyl group. As G and G¹Examples thereof may include a group represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29), and a chain hydrocarbon group having 4-valent carbon atoms of 6 or less. Among them, the group represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26) or formula (27) is preferable in terms of ease of suppressing the yellowness (YI value) of the transparent resin film.

In the formulae (20) to (29),

the symbol represents a chemical bond,

z represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-Ar-、-SO₂-、-CO-、-O-Ar-O-、-Ar-O-Ar-、-Ar-CH₂-Ar-、-Ar-C(CH₃)₂-Ar-or-Ar-SO₂-Ar-. Ar represents an arylene group having 6 to 20 carbon atoms which may be substituted with a fluorine atom, and specific examples thereof include a phenylene group.

In formula (12), G²The organic group having a valence of 3 is preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As G²Examples thereof may include a group obtained by replacing any of the chemical bonds of the group represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29) with a hydrogen atom, and a chain hydrocarbon group having 3-valent carbon atoms of 6 or less.

In formula (13), G³The organic group having a valence of 2 is preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As G³Examples of the "hydrocarbon chain group" may include a group obtained by substituting hydrogen atoms for non-adjacent 2 of the chemical bonds of the group represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29), and a hydrocarbon chain group having 6 or less carbon atoms.

A, A in formulae (10) to (13)¹、A²And A³Each independently is a 2-valent organic group, preferably an organic group which may be substituted with a hydrocarbyl group or a fluoro-substituted hydrocarbyl group. As A, A¹、A²And A³Examples of the "substituent" may include a group represented by formula (30), formula (31), formula (32), formula (33), formula (34), formula (35), formula (36), formula (37) or formula (38); a group obtained by substituting the above-mentioned 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 the formulae (30) to (38),

the symbol represents a chemical bond,

Z¹、Z²and Z³Each independently represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or-CO-.

As 1 example, Z¹And Z³is-O-, and, Z²is-CH₂-、-C(CH₃)₂-、-C(CF₃)₂-or-SO₂-。Z¹And Z²Bonding position with respect to each ring, and Z²And Z³The bonding position to each ring is preferably meta or para to each ring.

From the viewpoint of improving the visibility, the polyimide-based resin is preferably a polyamide imide having at least a repeating structural unit represented by formula (10) and a repeating structural unit represented by formula (13). The polyamide resin preferably has at least a repeating structural unit represented by formula (13).

In one embodiment of the present invention, the polyimide-based resin is a condensation-type polymer obtained by reacting (polycondensing) a diamine with a tetracarboxylic acid compound (e.g., an acid chloride compound or a tetracarboxylic acid dianhydride analog), and optionally a dicarboxylic acid compound (e.g., an acid chloride compound or a dicarboxylic acid compound analog), a tricarboxylic acid compound (e.g., an acid chloride compound or a tricarboxylic acid anhydride analog), and the like. The repeating structural unit represented by formula (10) or formula (11) may be generally derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by formula (12) may be generally derived from diamine and tricarboxylic acid compounds. The repeating structural unit represented by formula (13) may be generally derived from diamine and dicarboxylic acid compounds.

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

Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydride; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used alone or in combination of 2 or more. The tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound, in addition to a dianhydride.

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

Examples of the aliphatic tetracarboxylic dianhydride include cyclic and acyclic aliphatic tetracarboxylic dianhydrides. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include cycloalkanetetracarboxylic dianhydrides such as 1,2,4, 5-cyclohexanetetracarboxylic dianhydride, 1,2,3, 4-cyclobutanetetracarboxylic dianhydride and 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. These may be used alone or in combination of 2 or more. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydride include 1,2,3, 4-butanetetracarboxylic acid dianhydride, 1,2,3, 4-pentanetetracarboxylic acid dianhydride, and the like, and these can be used alone or in combination of 2 or more. In addition, cyclic aliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

Among the tetracarboxylic dianhydrides, 1,2,4, 5-cyclohexane tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, 4' - (hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof are preferable from the viewpoint of high transparency and low coloring property. In addition, as the tetracarboxylic acid, an aqueous adduct of an anhydride of the above tetracarboxylic acid compound can be used.

Examples of the tricarboxylic acid compound include an aromatic tricarboxylic acid, an aliphatic tricarboxylic acid, and a chloride compound and an acid anhydride similar thereto, and 2 or more kinds thereof may be used in combination. Specific examples thereof include anhydrides of 1,2, 4-benzenetricarboxylic acid; 2,3, 6-naphthalene tricarboxylic acid-2, 3-anhydride; phthalic anhydride and benzoic acid via single bond, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or phenylene groups.

The dicarboxylic acid compound includes aromatic dicarboxylic acid, aliphatic dicarboxylic acid, and the like, and acid chloride compounds and acid anhydrides thereof, and 2 or more of these may be used in combination. Specific examples thereof include terephthaloyl dichloride (terephthaloyl chloride (TPC)); isophthaloyl dichloride; naphthaloyl dichloride; 4, 4' -biphenylenedioyl dichloride; 3, 3' -biphenylene dicarboxylic acid dichloride; 4,4 '-oxybis (benzoyl chloride) (OBBC, 4, 4' -oxybis (benzoyl chloride)); a dicarboxylic acid compound of a chain hydrocarbon having 8 or less carbon atoms and 2 benzoic acids via a single bond, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or phenylene groups.

Examples of the diamine include aliphatic diamines, aromatic diamines, and mixtures thereof. In the present embodiment, the "aromatic diamine" refers to a diamine in which an amino group is directly bonded to an aromatic ring, and a part of the structure of the diamine may include an aliphatic group or another substituent. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring, but are not limited thereto. Of 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 a part of the structure of the diamine may contain an aromatic ring or other substituent.

Examples of the aliphatic diamine include acyclic aliphatic diamines such as 1, 6-hexamethylenediamine and cyclic aliphatic diamines such as 1, 3-bis (aminomethyl) cyclohexane, 1, 4-bis (aminomethyl) cyclohexane, norbornanediamine and 4, 4' -diaminodicyclohexylmethane. These may be used alone or in combination of 2 or more.

Examples of the aromatic diamine include aromatic diamines having 1 aromatic ring such as p-phenylenediamine, m-phenylenediamine, 2, 4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1, 5-diaminonaphthalene, and 2, 6-diaminonaphthalene; 4,4 ' -diaminodiphenylmethane, 4 ' -diaminodiphenylpropane, 4 ' -diaminodiphenyl ether, 3 ' -diaminodiphenyl ether, 4 ' -diaminodiphenyl sulfone, 3 ' -diaminodiphenyl sulfone, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 4 ' -diaminodiphenyl sulfone, bis [4- (4-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2,4 ' -diaminodiphenyl sulfone, 3 ' -diaminodiphenyl sulfone, 1,4 ' -diaminodiphenyl sulfone, 1,3 ' -bis (4-aminophenoxy) phenyl ] sulfone, 2-bis (4- (3-aminophenoxy), Aromatic diamines having 2 or more aromatic rings, such as 2,2 ' -dimethylbenzidine, 2 ' -bis (trifluoromethyl) benzidine (2,2 ' -bis (trifluoromethyl) -4,4 ' -diaminobiphenyl (TFMB)), 4 ' -bis (4-aminophenoxy) biphenyl, 9-bis (4-aminophenyl) fluorene, 9-bis (4-amino-3-methylphenyl) fluorene, 9-bis (4-amino-3-chlorophenyl) fluorene, and 9, 9-bis (4-amino-3-fluorophenyl) fluorene. These may be used alone or in combination of 2 or more.

Among the above diamines, from the viewpoint of high transparency and low coloring property, 1 or more selected from the group consisting of aromatic diamines having a biphenyl structure is preferably used, more preferably 1 or more selected from the group consisting of 2,2 ' -dimethylbenzidine, 2 ' -bis (trifluoromethyl) benzidine, 4 ' -bis (4-aminophenoxy) biphenyl, and 4,4 ' -diaminodiphenyl ether is used, and still more preferably 2,2 ' -bis (trifluoromethyl) benzidine is used.

The polyimide-based resin can be obtained by: the above-mentioned raw materials such as diamine, tetracarboxylic acid compound, tricarboxylic acid compound and dicarboxylic acid compound are mixed by a conventional method such as stirring, and then the obtained intermediate is imidized in the presence of an imidization catalyst and, if necessary, a dehydrating agent. The polyamide resin can be obtained by mixing the above-mentioned diamine, dicarboxylic acid compound and other raw materials by a conventional method, for example, by stirring.

The imidization catalyst used in the imidization step is not particularly limited, and examples thereof include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; n-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepinoAlicyclic amines (monocyclic); azabicyclo [2.2.1]Heptane, azabicyclo [3.2.1]Octane, azabicyclo [2.2.2]Octane, and azabicyclo [3.2.2]Alicyclic amines (polycyclic) such as nonane; and aromatic amines such as 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2, 4-dimethylpyridine, 2,4, 6-trimethylpyridine, 3, 4-cyclopentenopyridine, 5,6,7, 8-tetrahydroisoquinoline, and isoquinoline.

The dehydrating agent used in the imidization step is not particularly limited, and examples thereof include acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, and isovaleric anhydride.

In the mixing and imidizing step of the raw materials, the reaction temperature is not particularly limited, and is, for example, 15 to 350 ℃, preferably 20 to 100 ℃. The reaction time is also not particularly limited, and is, for example, about 10 minutes to 10 hours. If necessary, the reaction may be carried out in an inert atmosphere or under reduced pressure. The reaction may be carried out in a solvent, and examples of the solvent include solvents that can be used for the preparation of varnish. After the reaction, the polyimide-based resin or the polyamide-based resin is purified. Examples of the purification method include the following methods: a poor solvent is added to the reaction solution, a resin is precipitated by reprecipitation, and the precipitate is taken out by drying, and if necessary, the precipitate is washed with a solvent such as methanol and dried.

For example, the production method described in jp 2006-199945 a or 2008-163107 a can be referred to for the production of the polyimide resin. Further, commercially available products of polyimide-based resins can be used, and specific examples thereof include Neopulim (registered trademark) manufactured by Mitsubishi gas chemical corporation, KPI-MX300F manufactured by the river village industry corporation, and the like.

The weight average molecular weight of the polyimide-based resin or the polyamide-based resin is preferably 200,000 or more, more preferably 250,000 or more, further preferably 300,000 or more, preferably 600,000 or less, and more preferably 500,000 or less. The larger the weight average molecular weight of the polyimide-based resin or the polyamide-based resin is, the more easily the polyimide-based resin or the polyamide-based resin exhibits high bending resistance when formed into a film. Therefore, the weight average molecular weight is preferably not less than the above-described lower limit from the viewpoint of improving the bending resistance of the transparent resin film. On the other hand, as the weight average molecular weight of the polyimide-based resin or the polyamide-based resin is smaller, the viscosity of the varnish tends to be lower, and the processability tends to be improved. Further, the stretchability of the polyimide-based resin or the polyamide-based resin tends to be easily improved. Therefore, the weight average molecular weight is preferably not more than the above upper limit from the viewpoint of processability and stretchability. In the present application, the weight average molecular weight can be determined by Gel Permeation Chromatography (GPC) measurement in terms of standard polystyrene, and can be calculated by the method described in examples, for example.

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

In a preferred embodiment of the present invention, the polyimide-based resin or the polyamide-based resin contained in the transparent resin film of the present invention may contain a halogen atom such as a fluorine atom, which can be introduced through the above-mentioned fluorine-containing substituent or the like. When the polyimide-based resin or the polyamide-based resin contains a halogen atom, the elastic modulus of the transparent resin film is easily increased, and the yellowness (YI value) is easily decreased. When the elastic modulus of the transparent resin film is high, the occurrence of scratches, wrinkles, and the like in the film is easily suppressed, and when the yellowness index of the transparent resin film is low, the transparency of the film is easily improved. The halogen atom is preferably a fluorine atom. Examples of the fluorine-containing substituent which is preferable for containing a fluorine atom in the polyimide resin or the polyamide resin include a fluorine group and a trifluoromethyl group.

The content of the halogen atom 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 30% by mass, based on the mass of the polyimide resin or the polyamide resin. When the content of the halogen atom is within the above range, the elastic modulus at the time of forming a film is easily further increased, the water absorption is reduced, the yellowness (YI value) is further reduced, the transparency is further improved, and the synthesis is easily performed in some cases.

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

[ additives ]

The transparent resin film of the present invention may further contain an additive such as a filler. Examples of such additives include 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 comprise silica particles as an additive. The content of the silica particles is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 45 parts by mass or less, per 100 parts by mass of the transparent resin film. The content of the silica particles may be combined by selecting any of the upper limit and the lower limit. When the content of the silica particles is within the numerical range of the upper limit and/or the lower limit, the silica particles are less likely to aggregate and tend to be uniformly dispersed in the state of primary particles in the transparent resin film of the present invention, and therefore, the deterioration in visibility of the transparent resin film of the present invention can be suppressed.

The particle diameter of the silica particles is preferably 1nm or more, more preferably 3nm or more, further preferably 5nm or more, particularly preferably 8nm or more, preferably 30nm or less, more preferably 28nm or less, further preferably 25nm or less, and particularly preferably 20nm or less. The particle size of the silica particles can be combined by selecting any lower limit value and any upper limit value of these upper limit value and lower limit value. When the content of the silica particles is within the numerical range of the upper limit and/or the lower limit, the transparent resin film of the present invention is less likely to interact with light of a specific wavelength in white light, and thus deterioration in visibility of the transparent resin film can be suppressed. In the present specification, the particle size of the silica particles means an average primary particle size. The particle diameter of the silica particles in the transparent resin film can be measured from a photograph using a Transmission Electron Microscope (TEM). The particle diameter of the silica particles before the transparent resin film is produced (for example, before the transparent resin film is added to a varnish) can be measured by a laser diffraction particle size distribution meter.

Examples of the form of the silica particles include silica sol in which silica particles are dispersed in an organic solvent or the like, and silica powder produced by a vapor phase method. Among these, silica sol is preferable from the viewpoint of handling properties.

The silica particles may be subjected to a surface treatment, and may be, for example, silica particles obtained by solvent (more specifically, γ -butyrolactone or the like) substitution from a water-soluble alcohol-dispersed silica sol. The water-soluble alcohol has not more than 3 carbon atoms per 1 hydroxyl group in 1 molecule of the water-soluble alcohol, and examples thereof include methanol, ethanol, 1-propanol, and 2-propanol. Although depending on the compatibility of the silica particles with the type of polyimide-based polymer, generally, when the silica particles are surface-treated, the compatibility with the polyimide-based polymer contained in the transparent resin film tends to be improved, and the dispersibility of the silica particles tends to be improved, so that the deterioration of the visibility of the present invention can be suppressed.

(ultraviolet absorber)

The transparent resin film of the present invention may further contain an ultraviolet absorber. Examples thereof include triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzoate-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. These may be used alone, or 2 or more of them may be used in combination. Preferable examples of the commercially available ultraviolet absorber include Sumisorb (registered trademark) 340 manufactured by Sumika Chemtex Company, Limited, ADK STAB (registered trademark) LA-31 manufactured by ADEKA, and TINUVIN (registered trademark) 1577 manufactured by BASF Japan. The content of the ultraviolet absorber is preferably 1phr or more and 10phr or less, more preferably 3phr or more and 6phr or less, based on the mass of the transparent resin film of the present invention.

(whitening agent)

The transparent resin film of the present invention may further contain a whitening agent. For example, in the case of adding an additive other than a whitening agent, the whitening agent may be added for color adjustment. Examples of the whitening agent include monoazo dyes, triarylmethane dyes, phthalocyanine dyes, and anthraquinone dyes. Among these, anthraquinone dyes are preferable. Examples of a preferable commercially available whitening agent include MACROLEX (registered trademark) Violet B manufactured by LANXESS corporation, semika Chemtex Company, semiplast (registered trademark) Violet B manufactured by Limited, and Diaresin (registered trademark) Blue G manufactured by mitsubishi chemical corporation. These may be used alone, or 2 or more of them may be used in combination. The content of the whitening agent is preferably 5ppm to 40ppm based on the mass of the transparent resin film of the present invention.

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

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

[ method for producing transparent resin film ]

The transparent resin film in the present invention is not particularly limited, and can be produced, for example, by a method including the following steps:

(a) a step of preparing a liquid (hereinafter, sometimes referred to as a varnish) containing the resin and the filler (varnish preparation step);

(b) a step (coating step) of applying a varnish to a substrate to form a coating film; and

(c) and a step of drying the applied varnish (coating film) to form a transparent resin film (transparent resin film forming step).

In the varnish preparation step, the resin is dissolved in a solvent, and the filler and, if necessary, other additives are added thereto and stirred and mixed to prepare a varnish. When silica is used as the filler, a silica sol obtained by replacing a dispersion of a silica sol containing silica with a solvent capable of dissolving the resin (for example, a solvent used in the preparation of a varnish described below) may be added to the resin.

The solvent used in the preparation of the varnish is not particularly limited as long as the aforementioned resin can be dissolved. Examples of the solvent include amide solvents such as N, N-dimethylacetamide (DMAc) and N, N-Dimethylformamide (DMF); lactone solvents such as γ -butyrolactone (GBL) and γ -valerolactone; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; carbonate-based solvents such as ethylene carbonate and 1, 2-propylene carbonate; and combinations thereof. Among these, amide solvents or lactone solvents are preferable. These solvents may be used alone or in combination of two or more. The varnish may contain 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 mass%, more preferably 5 to 20 mass%.

In the coating step, a varnish is applied to a substrate by a known coating method to form a coating film. Examples of known coating methods include roll coating methods such as wire bar coating, reverse coating, and gravure coating, die coating, comma coating, lip coating, screen coating, spray coating, and cast molding.

In the transparent resin film forming step, the coating film is dried and peeled from the substrate, whereby a long strip-shaped transparent resin film can be formed.

Examples of the substrate include an SUS endless belt if the substrate is a metal type, and a long belt-shaped PET film, a PEN film, another polyimide-based resin, a polyamide-based resin film, a cycloolefin-based polymer (COP) film, and an acrylic film if the substrate is a resin type. Among them, 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.

When the substrate is peeled off, peeling electrification generally occurs, and therefore, it is preferable to remove static electricity from the film.

For example, a Nano static eliminator can be used to remove electric charges, and examples thereof include a Nano static eliminator manufactured by Wedge Holdings co. Further, an ionizer may be used, or they may be used in combination.

After the peeling, a heat treatment step of drying the transparent resin film is further performed. The heat treatment of the coating film can be carried out at a temperature of 50 to 350 ℃. If necessary, the coating film may be dried in an inert atmosphere or under reduced pressure.

In the heat treatment, both end portions of the long strip-shaped transparent resin film are respectively gripped, and the gripped film is conveyed while the width of the gripped film is set to a predetermined distance, and the heat treatment is performed while the film is conveyed in, for example, a dryer. The width of the film in the heat treatment can be set as appropriate.

The handling of the membrane can be performed, for example, by using a plurality of clamps.

The plurality of grippers may be fixed to an endless chain of a predetermined length, which moves at the same speed as the film, according to the size of the conveyor, and grippers are provided at appropriate positions of the chain to grip the transparent resin film before entering the dryer, and to release the gripping at the time point when the transparent resin film is removed from the dryer.

The plurality of clips provided at one end of the film are provided such that the space between adjacent clips is, for example, 1 to 50mm, preferably 3 to 25mm, and more preferably 5 to 10 mm.

After removal from the dryer, the film is released from its grip and the film can be slit after release.

The present invention also provides a transparent resin film having a small amount of charge, in other words, a high static charge removing rate. The static charge removing rate can be measured, for example, in the manner described in examples.

The resin film is provided in which the ratio of the region where the toner is not adhered is 60% or more of the area where the toner is scattered. The ratio of the region where the toner is not attached is preferably 70% or more, and more preferably 80% or more.

[ protective film ]

In the present invention, a transparent resin film is bonded to a protective film.

Before the lamination, the transparent resin film was passed through a stain removing roller to remove stains present on the surface. In this case, the stain removing roller is separated immediately after coming into contact with the transparent resin film temporarily, but at this time, the internal charge of the transparent resin film is usually removed because of electrification. For this static elimination, the aforementioned nano static eliminating device can be used.

The protective film is bonded to the surface of the transparent resin film having no support. When the laminate is wound in a roll form, there is a problem of winding properties such as blocking, a protective film may be additionally attached to the surface of the support opposite to the transparent resin film. The protective film to be 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 capable of protecting the surface of the transparent resin film. Examples thereof include polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; the resin film is preferably selected from the group consisting of polyolefin resin films, polyethylene, polypropylene films and the like, acrylic resin films and the like. When the protective films are bonded to both surfaces of the laminate, the protective films on the respective surfaces may be the same or different from each other.

The thickness of the protective film is not particularly limited, but is usually 10 to 100 μm, preferably 10 to 80 μm. When the protective films are bonded to both surfaces of the laminate, the thicknesses of the protective films on the respective surfaces may be the same or different.

After the protective film is bonded to the transparent resin film, the film can be cut into a desired width.

Next, the transparent resin film with the protective film attached thereto was wound in a roll shape to obtain a resin film roll. The film is cut from the obtained roll to a size required for use as, for example, a front panel of a flexible device.