KR102103487B1 - Method for producing transparent resin film - Google Patents

Abstract

[Problem] A method for producing a transparent resin film that can obtain a homogeneous transparent resin film is provided.
[Solutions] A step of holding both ends of a long strip-shaped transparent resin film comprising at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins, and a step of conveying the gripped film, The step of making the width of the gripped film a predetermined distance, and heat-treating the resin film in a dryer, so that the ratio of the width of the film after heat treatment to the width of the film before heat treatment is 1.1 or less, and the resin film from the dryer The manufacturing method of the transparent resin film which has the process of releasing the gripping of.

Description

Manufacturing method of transparent resin film {METHOD FOR PRODUCING TRANSPARENT RESIN FILM}

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

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

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

By the way, when performing such heat treatment, the uniformity of the obtained transparent resin film may not be obtained in some cases.

Japanese Patent Application Publication No. 2010-36414

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

That is, the present invention provides the following.

[1] A process of gripping both ends of a long strip-shaped transparent resin film comprising at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins, a process of conveying a gripped film, and a gripping The process of making the width of the film | membrane into a predetermined distance, and heat-processing the said resin film in a dryer, and making the ratio of the width of the film after heat processing to the width of the film before heat processing to 1.1 or less, and the resin film from the dryer. The manufacturing method of the transparent resin film which has the process of releasing a phage.

[2] The production method according to [1], wherein the ratio of the width of the film after heat treatment to the width of the film before heat treatment is 0.7 to 1.0.

[3] The production method according to [1] or [2], wherein the gripping is performed by a plurality of clips.

[4] The production method according to [3], in which the driving device equipped with the clip moves at the same speed as the conveying speed of the film.

[5] The manufacturing method according to [4], wherein the drive is driven by a chain.

[6] The production method according to any one of [3] to [5], wherein a space between adjacent clips is 1 to 20 mm.

[7] When the straight line orthogonal to the film transport axis is aligned with the center of the gripping portion of the clip at one end of the film, the distance between the intersection of the straight line and the other end of the film and the center of the gripping portion of the clip at the other end of the film is 3 mm or less, The production method according to any one of [3] to [6].

[8] The production method according to any one of [1] to [7], wherein the content of the organic solvent contained in the resin film after heat treatment is 0.001 to 3% by mass relative to the mass of the resin film.

[9] The production method according to any one of [1] to [8], having a step of slitting both ends of the film after releasing the gripping of the film.

[10] The production method according to [9], comprising a step of bonding the protective film to the resin film after slitting the film.

[11] The production method according to [10], having a step of slitting the resin film to which the protective film is bonded after bonding the protective film.

[12] The production method according to [10] or [11], comprising a step of winding the resin film onto a roll after bonding the protective film.

As mentioned above, this invention provides the manufacturing method of the transparent resin film which can obtain a homogeneous transparent resin film.

1 shows an example of a dryer for producing a transparent resin film according to the present invention. The film is conveyed from left to right on the ground. (a) represents the side perspective view of the dryer, and the center line represents the situation in which the film is conveyed. (b) shows the top view of the dryer, and the center square indicates the situation in which the film is conveyed.

The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not necessarily limited to them, and can be performed by appropriately changing the scope without changing the subject matter.

The present invention is a step of gripping both ends of a long strip-shaped transparent resin film comprising at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins, and conveying the gripped film, The step of making the width of the gripped film a predetermined distance, and heat-treating the resin film in a dryer, so that the ratio of the width of the film after heat treatment to the width of the film before heat treatment is 1.1 or less, and the resin film from the dryer It provides a method for producing a transparent resin film having a step of releasing the grip.

[Polyimide resin, polyamide resin]

The transparent resin film of the present invention contains at least one resin selected from the group consisting of polyimide resins and polyamide resins. The 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, It represents at least 1 type of polymer chosen from the group which consists of polyamideimide.). Moreover, a polyamide resin represents a polymer containing a repeating structural unit containing an amide group.

It is preferable that a polyimide resin has a repeating structural unit represented by Formula (10). Here, G is a tetravalent organic group, and A is a divalent organic group. The polyimide-based resin may contain a repeating structural unit represented by two or more kinds of formulas (10) in which G and / or A are different.

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

In Formulas (10) and (11), G and G ¹ are each independently a tetravalent organic group, and preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As G and G ¹ , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) Or the group represented by Formula (29) and a tetravalent C6-C6 or less chain hydrocarbon group are illustrated. Since the yellowness (YI value) of the transparent resin film is easily suppressed, among them, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), The group represented by formula (26) or formula (27) is preferred.

In equation (20) to equation (29),

* Represents a bonding hand,

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 -Ar-SO ₂ -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), 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. As G ² , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula A group in which any one of the bonds of the group represented by (29) is substituted with a hydrogen atom, and a trivalent carbon group having 6 or less carbon atoms are exemplified.

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

In Formulas (10) to (13), A, A ¹ , A ² and A ³ are each independently a divalent organic group, and may be preferably substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group. As A, A ¹ , A ² and A ³ , equation (30), equation (31), equation (32), equation (33), equation (34), equation (35), equation (36), equation (37) ) Or a group represented by formula (38); Groups in which they are substituted 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 is exemplified.

In equation (30) to equation (38),

* Represents a bonding hand,

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-.

In one example, Z ¹ and Z ³ are -O-, and Z ² is -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -or -SO _2- . The bonding position for each ring of Z ¹ and Z ² and the bonding position for each ring of Z ² and Z ³ are preferably meta positions or para positions for each ring, respectively.

It is preferable that the polyimide resin is a polyamideimide having at least a repeating structural unit represented by formula (10) and a repeating structural unit represented by formula (13) from the viewpoint of easy to improve visibility. Moreover, it is preferable that a polyamide resin has at least the repeating structural unit represented by Formula (13).

In one embodiment of the present invention, the polyimide-based resin includes diamines and tetracarboxylic acid compounds (tetracarboxylic acid compound analogs such as acid chloride compounds and tetracarboxylic dianhydrides), If necessary, dicarboxylic acid compounds (dicarboxylic acid compound analogs such as acid chloride compounds), tricarboxylic acid compounds (trichloric acid compound analogs of acid chloride compounds, tricarboxylic acid anhydrides, etc.), etc. It is a condensation type polymer obtained by reacting (polycondensation). The repeating structural unit represented by formula (10) or formula (11) is usually derived from diamine and tetracarboxylic acid compounds. The repeating structural unit represented by formula (12) is usually derived from diamine and tricarboxylic acid compounds. The repeating structural unit represented by formula (13) is usually derived from diamine and dicarboxylic acid compounds.

In one embodiment of the present invention, the polyamide-based 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 formula (13) is usually derived from diamine and dicarboxylic acid compounds.

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 two or more. In addition to the dianhydride, the tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound.

As a specific example of aromatic tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic 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 Dihydrate, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 1,2-bis ( 2,3-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 '-(p-phenylenedioxy) diphthalic dianhydride and 4,4'-(m-phenylenedioxy) diphthalic dianhydride. These can be used alone or in combination of two or more.

As an aliphatic tetracarboxylic dianhydride, a cyclic or acyclic aliphatic tetracarboxylic dianhydride is mentioned. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2, Cycloalkane tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7, such as 3,4-cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclopentanetetracarboxylic dianhydride -Ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3 ', 4,4'-tetracarboxylic dianhydride and positional isomers thereof. 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, 1,2,3,4-pentanetetracarboxylic dianhydride, and the like. Silver may be used alone or in combination of two or more. Moreover, you may use combining a cyclic aliphatic tetracarboxylic dianhydride and a non-cyclic aliphatic tetracarboxylic dianhydride.

Among the above tetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3 from the viewpoint of high transparency and low colorability Preference is given to, 5,6-tetracarboxylic dianhydride and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof. Moreover, as a tetracarboxylic acid, you may use the water addition body of the anhydride of the said tetracarboxylic-acid compound.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and their flexible acid chloride compounds, acid anhydrides, and the like, and two or more kinds may be used in combination.

Specific examples include anhydrides of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; And a compound in which phthalic anhydride and benzoic acid are single-linked, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or a phenylene group.

As a dicarboxylic acid compound, aromatic dicarboxylic acid, aliphatic dicarboxylic acid, these flexible acid chloride compounds, acid anhydrides, etc. are mentioned, You may use 2 or more types together.

Specific examples of these include terephthalic acid dichloride (terephthaloyl chloride (TPC)); Isophthalic acid dichloride; Naphthalenedicarboxylic acid dichloride; 4,4'-biphenyldicarboxylic acid dichloride; 3,3'-biphenyldicarboxylic acid dichloride; 4,4'-oxybis (benzoylchloride) (OBBC); A dicarboxylic acid compound of a chain hydrocarbon having 8 or less carbon atoms and two benzoic acid single bonds, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or phenylene And compounds linked by groups.

Examples of diamines include aliphatic diamines, aromatic diamines, and mixtures thereof. In addition, in this embodiment, "aromatic diamine" refers to the diamine in which the amino group is directly bonded to the aromatic ring, and may contain an aliphatic group or other substituents in a part of the structure. 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. Among these, it is preferable that the aromatic ring is a benzene ring. Moreover, "aliphatic diamine" refers to the diamine in which the amino group is directly bonded to the aliphatic group, and may include an aromatic ring or other substituents in a part of the structure.

Examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylenediamine and 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4,4'- And cyclic aliphatic 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, 2,6- Aromatic diamines having one aromatic ring, such as diaminonaphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-dia Minodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) Benzene, 1,3-bis (4-aminophenoxy) benzene, 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 (tri Fluoromethyl) benzidine (2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB)), 4,4'-bis (4-aminophenoxy) biphenyl, 9 , 9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9-bis (4-amino-3-chlorophenyl) fluorene, 9, 2 or more aromatic rings, such as 9-bis (4-amino-3-fluorophenyl) fluorene There may be mentioned aromatic diamine. These can be used alone or in combination of two or more.

Among the diamines, from the viewpoint of high transparency and low coloration, it is preferable to use at least one member selected from the group consisting of aromatic diamines having a biphenyl structure, and 2,2'-dimethylbenzidine, 2,2'-bis ( It is more preferable to use at least one member selected from the group consisting of trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenyl ether, 2 It is more preferable to use, 2'-bis (trifluoromethyl) benzidine.

The polyimide-based resin is an intermediate obtained after mixing each of the raw materials such as the diamine, tetracarboxylic acid compound, tricarboxylic acid compound and dicarboxylic acid compound by a conventional method such as stirring. Is obtained by imidizing in the presence of an imidization catalyst and, if necessary, a dehydrating agent. The polyamide-based resin is obtained by mixing each raw material such as the diamine and dicarboxylic acid compound by a conventional method such as 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; Alicyclic amines (monocyclic) such as N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine; Alicyclic amines (polycyclic) such as azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2.2] octane, and 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 And aromatic amines such as 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 imidization step of each raw material, the reaction temperature is not particularly limited, but is, for example, 15 to 350 ° C, preferably 20 to 100 ° C. The reaction time is not particularly limited, but is, for example, about 10 minutes to 10 hours. If necessary, the reaction may be performed under an inert atmosphere or a reduced pressure condition. Moreover, reaction may be performed in a solvent, and what was illustrated as a solvent used for preparation of a varnish is mentioned as a solvent, for example. After the reaction, the polyimide resin or polyamide resin is purified. As a purification method, for example, a poor solvent is added to the reaction solution to precipitate a resin by a reprecipitation method, dried to extract the precipitate, and if necessary, the precipitate is washed with a solvent such as methanol and dried. Can be mentioned.

Moreover, you may refer to the manufacturing method of Unexamined-Japanese-Patent No. 2006-199945 or Unexamined-Japanese-Patent No. 2008-163107, for the manufacture of a polyimide system resin. In addition, commercially available products may be used as the polyimide-based resin, and specific examples thereof include Mitsubishi Gas Chemical Company, Inc., Neoprem (registered trademark), Kawamura Sangyo Co., Ltd. (Kawamura Sangyo Co., Ltd.) ., Ltd) KPI-MX300F.

The weight average molecular weight (Mw) of the polyimide-based resin or polyamide-based resin is preferably 200,000 or more, more preferably 250,000 or more, still more preferably 300,000 or more, and preferably 600,000 or less, more preferably 500,000 Is below. The larger the weight-average molecular weight of the polyimide-based resin or polyamide-based resin, the higher the tendency to exhibit high flex resistance when filmed. For this reason, from the viewpoint of increasing the bending resistance of the transparent resin film, it is preferable that the weight average molecular weight is equal to or greater than the above lower limit. On the other hand, the smaller the weight average molecular weight of the polyimide-based resin or polyamide-based resin, the lower the viscosity of the varnish tends to be, and tends to be easy to improve the processability. Moreover, the stretchability of a polyimide-type resin or a polyamide-type resin tends to improve easily. For this reason, from the viewpoint of processability and stretchability, it is preferable that the weight average molecular weight is equal to or less than the above upper limit. In addition, in this application, the weight average molecular weight can be calculated | required by gel permeation chromatography (GPC) measurement and calculated | required by standard polystyrene conversion, for example, can be calculated by the method described in the Example.

The imidation ratio of the polyimide resin is preferably 95 to 100%, more preferably 97 to 100%, further preferably 98 to 100%, particularly preferably 100%. From the viewpoint of the stability of the varnish and the mechanical properties of the obtained transparent resin film, it is preferable that the imidation ratio is equal to or greater than the above lower limit. Moreover, the imidation rate can be calculated | required by IR method, NMR method, etc. From the above viewpoint, it is preferable that the imidation ratio of the polyimide resin contained in the varnish is within the above range. The imidation rate can be obtained, for example, by the method described in Japanese Patent Application No. 2018-007523.

In one preferred embodiment of the present invention, the polyimide-based resin or polyamide-based resin contained in the transparent resin film of the present invention can be introduced by, for example, a fluorine-containing substituent or the like, a halogen such as a fluorine atom. It may contain an atom. 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 reduce the yellowness (YI value). When the elastic modulus of the transparent resin film is high, it is easy to suppress the occurrence of scratches and wrinkles in the film, and when the yellowness of the transparent resin film is low, it is easy to improve the transparency of the film. The halogen atom is preferably a fluorine atom. As a preferable fluorine-containing substituent in order to contain a fluorine atom in a polyimide resin or a polyamide resin, a fluoro group and a trifluoromethyl group are mentioned, for example.

The content of the halogen atom in the polyimide-based resin or polyamide-based resin is preferably 1 to 40% by mass, more preferably 5 to 40% by mass, based on the mass of the polyimide-based resin or polyamide-based resin. %, More preferably 5 to 30% by mass. When the content of the halogen atom is 1% by mass or more, the elastic modulus at the time of film formation is further improved, the absorption rate is lowered, 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, synthesis may be easy.

In one embodiment of the present invention, the content of the polyimide-based resin and / or polyamide-based resin in the transparent resin film is preferably 40% by mass or more, more preferably based on the total mass of the transparent resin film. Preferably it is 50 mass% or more, More preferably, it is 70 mass% or more. The content of the polyimide-based resin and / or the polyamide-based resin is preferably at least the above lower limit from the viewpoint of easy to increase flexural resistance and the like. The content of the polyimide-based resin and / or polyamide-based 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 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 contain 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, more preferably 5 parts by mass or more, and preferably 60 parts by mass or less, more preferably 100 parts by mass of the transparent resin film It is preferably 50 parts by mass or less, and more preferably 45 parts by mass or less. Moreover, content of a silica particle can select and combine arbitrary lower limit and an upper limit among these upper limit and a lower limit. When the content of the silica particles is in the numerical range of the upper limit and / or the lower limit, in the transparent resin film of the present invention, the silica particles are hardly agglomerated and tend to be uniformly dispersed in the primary particle state. The decrease in visibility of the transparent resin film can be suppressed.

The particle size of the silica particles is preferably 1 nm or more, more preferably 3 nm or more, more preferably 5 nm or more, particularly preferably 8 nm or more, preferably 30 nm or less, more preferably 28 nm or less, and more preferably Is 25 nm or less, particularly preferably 20 nm or less. The particle diameter of the silica particles can be combined by selecting an arbitrary lower limit and an upper limit from these upper and lower limits. If the content of the silica particles is in the numerical range of the upper and / or lower limits, the transparent resin film in the present invention is difficult to interact with light of a specific wavelength in white light, and thus the visibility of the transparent resin film Can suppress the drop. In this specification, the particle diameter of the silica particles represents the average primary particle diameter. The particle diameter of the silica particles in the transparent resin film can be measured by imaging using a transmission electron microscope (TEM). The particle diameter of the silica particles before producing the transparent resin film (for example, before adding to the varnish) can be measured by a laser diffraction particle size distribution system.

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

The silica particles may be subjected to a surface treatment, for example, silica particles substituted with 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 examples thereof include methanol, ethanol, 1-propanol, and 2-propanol. Although it differs depending on the reciprocity of the type of the silica particles and the polyimide-based polymer, usually, when the silica particles are surface treated, the compatibility with the polyimide-based 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 the decrease in visibility of the present invention.

(Ultraviolet absorbent)

The transparent resin film in the present invention may further contain an ultraviolet absorber. For example, 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 in combination of two or more. Suitable commercially available ultraviolet absorbers include, for example, Sumisorb (registered trademark) 340 manufactured by Sumika Chemtex Company, Limited, Adekastab (registered trademark) LA-31 manufactured by ADEKA Corporation, and And Tinuvin (registered trademark) 1577 manufactured by BASF Japan Corporation. The content of the ultraviolet absorber is preferably 1 phr or more and 10 phr or less, more preferably 3 phr or more and 6 phr or less, based on the mass of the transparent resin film in the present invention.

(Whitening agent)

The transparent resin film in the present invention may further contain a brightener. The brightener can be added, for example, in order to adjust the color sense when additives other than the brightener are added. Examples of the brightener include monoazo dyes, triarylmethane dyes, phthalocyanine dyes, and anthraquinone dyes. Among these, anthraquinone-based dyes are preferred. Suitable commercially available brighteners include, for example, Macrolex (registered trademark) Violet B manufactured by LANXESS, Sumiplast (registered trademark) Violet B manufactured by Sumika Chemtex, and Mitsubishi Chemical Co., Ltd. And Diaresin (registered trademark) Blue G manufactured by (Mitsubishi Chemical Corporation). These may be used alone or in combination of two or more. When a whitening agent is included, the content is preferably 1 to 50 ppm, more preferably 1 to 45 ppm, more preferably 3 to 40 ppm, and more, based on the mass of the transparent resin film in the present invention. It is preferably 5 to 35 ppm.

The use of the transparent resin film in the present invention is not particularly limited, and may be used for various purposes. As described above, the transparent resin film may be a single layer or a laminate, or the transparent resin film may be used as it is, or may be used as a laminate with another film. Since this 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 panel of an image display device, particularly as a front panel (window film) of a flexible display. The flexible display has, for example, a flexible functional layer and the polyimide-based film that is superimposed on the flexible functional layer and functions as a front plate. That is, the front panel of the flexible display is disposed on the viewing side on the flexible functional layer. This front plate has a function of protecting the flexible functional layer.

[Method for manufacturing transparent resin film]

Although the transparent resin film in this invention is not specifically limited, For example, the following processes:

(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 of applying a varnish to the substrate to form a coating film (coating step), and

(c) Process of drying the applied liquid (coating film) to form a transparent resin film (transparent resin film forming process)

It can be manufactured by a method comprising a.

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 stirring and mixing. Moreover, when using silica as a filler, you may add the silica sol which substituted the dispersion of the silica sol containing silica with the solvent which the said resin is soluble, for example, the solvent used for preparation of the following varnish to resin.

The solvent used for the preparation of the varnish is not particularly limited as long as the resin can be dissolved. Examples of such a solvent include amide solvents such as N, N-dimethylacetamide (DMAc) and N, N-dimethylformamide; lactone-based 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 propylene carbonate; And combinations thereof. Among these, an amide-based solvent or a lactone-based solvent is preferable. These solvents may be used alone or in combination of two or more. Moreover, 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% 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. As a known coating method, for example, a wire bar coating method, reverse coating, gravure coating, roll coating method, die coating method, comma coating method, lip coating method, screen coating method, fountain coating method, spraying method, flexible ( Iv) molding methods and the like.

In a transparent resin film forming process, a long band-shaped transparent resin film can be formed by drying and peeling a coating film from a base material. You may perform the heat processing process of further drying a transparent resin film after peeling. The heat treatment of the coating film can be usually performed at a temperature of 50 to 350 ° C. If necessary, the coating film may be dried under an inert atmosphere or under reduced pressure.

In the heat treatment, both ends of the long strip-shaped transparent resin film are respectively gripped, and the width of the gripped film is set to a predetermined distance while conveying the gripped film, for example, heat treatment is performed while conveying in a dryer. At this time, the ratio of the width of the film after the heat treatment (excluding the gripping portion) to the width of the film before the heat treatment (excluding the gripping portion) is set to 1.1 or less, and to release the gripping of the resin film from the dryer. Thereby, heat processing of a transparent resin film can be performed.

The ratio of the width of the film after the heat treatment (excluding the gripping portion) to the width of the film before the heat treatment (excluding the gripping portion) (hereinafter sometimes referred to as stretching ratio) is preferably 0.7 to 1.0, More preferably, it is 0.7 to 0.98. In addition, since stretching is not performed between the portion where the film is held and the end of the film, it is excluded from the film width when calculating the stretching ratio.

The gripping of the film is performed at both ends of the film by using a plurality of clips, for example.

The plurality of clips can be fixed to an endless chain of a predetermined length, depending on the size of the conveying device, the chain moves at the same speed as the film, and the clips are installed at appropriate positions on the chain to enter the dryer. The transparent resin film was gripped before, and the gripping was released at the time when the dryer exited.

In the case of a plurality of clips provided at one end of the film, the distance between the adjacent clips, that is, the space between the clip on the front side and the clip on the rear side in the conveyance direction of the film, is preferably 1 to 50 mm, for example. It is installed to be 3 to 25 mm, more preferably 5 to 10 mm.

Moreover, the straight line A orthogonal to the film conveying axis is aligned with the center of the gripping portion of any clip at one end of the film, and the intersection of the straight line A and the other end of the film, the center of the gripping portion of the clip at the one end, and the intersection point. When the angle formed by the straight line B connecting the center of the grip portion of the clip closest to the angle is θ, θ may be preferably 2 ° or less, more preferably 1 ° or less, and more preferably 0.5 ° or less. . When θ is in the above range, optical properties such as, for example, retardation at the left and right sides of the film can be made homogeneous.

When the ratio of the width of the film after heat treatment to the width of the film before heat treatment (but not including the gripping portion) is within the above range, the film appearance tends to be improved.

Moreover, you may fix a film with a pin instead of a clip.

The amount of the solvent in the film after the heat treatment is preferably 0.001 to 3% by mass, more preferably 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, particularly preferably 0.001 to based on the mass of the film. It is 1.3 mass%. When the amount of the solvent in the film after heat treatment is in the above range, the film appearance tends to be good.

When the heat treatment is over and the film comes out from the dryer, the film is released from gripping, and the film end is preferably slit immediately. Cracking of the film due to the film being conveyed thereafter and the temperature lowered by removing the cracks that are likely to occur between the gripping portion and the non-gripping portion at the end of the film by performing a slit. Can be prevented in advance.

Examples of the base material include an endless belt made of SUS for a metal system, a PET film of a long belt type for a resin system, a PEN film, another polyimide resin or polyamide resin film, a cycloolefin polymer (COP) film, and an acrylic film. have. Especially, a PET film, a COP film, etc. are preferable from a viewpoint of excellent smoothness and heat resistance, and a PET film is more preferable from a viewpoint of adhesiveness with a transparent resin film and cost.

Protective film

In the present invention, the transparent resin film may include a protective film affixed to the transparent resin film to form a laminate. The protective film is affixed to the surface without the support of the transparent resin film. When winding up a laminated body in roll form, when there is a problem with winding property, such as blocking, in addition to the above, you may stick a protective film on the surface opposite to the transparent resin film of a support body. 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 capable of protecting the surface of the transparent resin film. For example, polyester resin films, such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; And polyolefin-based resin films, such as polyethylene and polypropylene films, and acrylic-based resin films, and is preferably selected from the group consisting of polyolefin-based resin films, polyethylene terephthalate-based resin films, and acrylic-based resin films. When the protective film is stuck on both surfaces of the laminate, the protective films on each surface may be the same or different.

Although the thickness of a protective film is not specifically limited, Usually, it is 10-100 micrometers, Preferably it is 10-80 micrometers. When a protective film is pasted on both surfaces of a laminate, the thickness of the protective film on each surface may be the same or different.

Laminate film roll

In the present invention, the layered body (support, transparent resin film and, if necessary, protective film) is wound in a roll form to a core, and is referred to as a layered film roll. In the case of continuous production, the laminate film roll is often stored in the form of a film roll once from space and other constraints, and the laminate film roll is one of them.

As a material constituting the core of the laminated film roll, for example, polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyester resin, epoxy resin, phenol resin, melamine resin, silicon resin, polyurethane resin, polycarbonate resin , ABS resin and other synthetic resins; Metals such as aluminum; And fiber-reinforced plastics (FRP: composite materials containing fibers such as glass fibers in plastics to improve strength) and the like. The winding core has a shape such as a cylindrical shape or a cylindrical shape, and its diameter is, for example, 80 to 170 mm. Moreover, although the diameter (diameter after winding) of a film roll is not specifically limited, Usually, it is 200-800 mm.

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

Example

Hereinafter, the effects of the present invention will be made more clear by examples. In addition, the present invention is not limited to the following examples, and can be carried out by appropriately changing the scope without changing the subject matter.

(Weight average molecular weight)

Gel permeation chromatography (GPC) measurements

(1) Pretreatment method

The sample was dissolved in γ-butyrolactone (GBL) to make a 20% by mass solution, diluted 100-fold with DMF eluent, and filtered with a 0.45 μm membrane filter as a measurement solution.

(2) Measurement conditions

Column: TSKgel SuperAWM-H × 2 + SuperAW2500 × 1 (6.0mm I.D. × 150mm × 3 pieces)

Eluent: DMF (addition of 10 mmol / L lithium bromide)

Flow rate: 0.6 mL / min

Detector: RI detector

Column temperature: 40 ° C

Injection volume: 20 μL

Molecular weight standard: standard polystyrene

<Measurement of imidation rate>

The imidation ratios of the polyimide resin and the polyimide resin used in Examples and Comparative Examples were measured by ¹ H-NMR and calculated using signals derived from the partial structures represented by the formula (Formula XXX). The method for calculating the imidation ratio from the measurement conditions and the obtained results is as follows.

(NMR measurement conditions)

Measuring device: Bruker 600MHz NMR device AVANCE600

Sample temperature: 303K

Measurement method: ¹ H-NMR, HSQC

(Calculation method of imidation ratio of polyimide resin)

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

<Measurement of total light transmittance (Tt)>

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

<Measurement of Haze>

The haze of the transparent resin film was measured according to JIS K 7105: 1981 by a fully automatic haze computer HGM-2DP manufactured by Suga Tester Co., Ltd. Table 3 shows the results.

<Measurement of yellowness (YI)>

The yellow index (yellowness: YI value) of the transparent resin film was measured by an ultraviolet visible near-infrared spectrophotometer V-670 manufactured by JASCO Corporation. After performing the background measurement in the absence of a sample, a transparent resin film was set in a sample holder, and the transmittance of 300 to 800 nm was measured for light to obtain tristimulus values (X, Y, Z). The YI value was calculated based on the following equation.

YI value = 100 × (1.2769X-1.0592Z) / Y

Table 3 shows the results.

<Measurement of residual solvent amount>

Using TG-DTA (EXSTAR6000 TG / DTA6300 manufactured by SII Co., Ltd.), the transparent resin films obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were heated from 30 ° C to 120 ° C and held at 120 ° C for 5 minutes. After that, the temperature was raised to 400 ° C at a rate of temperature increase of 5 ° C / min. The ratio of the mass reduction of the film from 120 ° C to 250 ° C with respect to the mass of the film at 120 ° C was calculated as the content of the solvent (referred to as the residual solvent amount). Table 3 shows the results.

<Crack>

The film was checked while the film was flowing 50 m from the position where the film fell from the clip to check for the presence or absence of cracks. Table 2 shows the results.

<Appearance>

The film was visually checked at a position where the film fell from the clip, and the film was checked while the film was flowing for 50 m, and the film was not broken and whether there was no wave like a tin (called a tin-like defect) was visually checked. Table 2 shows the results.

<Production Example 1: Preparation of polyimide-based resin (1)>

A flask equipped with a silica gel tube, a stirring device, and a thermometer, and an oil bath were prepared in the separable flask. In this flask, 75.6 g of 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl ( TFMB) 54.5g was added. 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 uniform solution. Subsequently, stirring was continued for an additional 20 hours while adjusting the temperature in the vessel to be in the range of 20 to 30 ° C using an oil bath, and reacted to produce polyamic acid. After 30 minutes, the stirring speed was changed to 100 rpm. After stirring for 20 hours, the reaction system temperature 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 stirred at room temperature for 10.5 hours to imidize. The polyimide varnish was taken out from the reaction vessel. The obtained polyimide varnish was added dropwise to methanol to reprecipitate, the resulting powder was dried by heating to remove the solvent to obtain a polyimide resin (1) as a solid content. When the GPC measurement was performed on the obtained polyimide resin (1), the weight average molecular weight (Mw) was 365,000. Moreover, the imidation ratio of the polyimide was 99.0%.

<Production Example 2: Preparation of polyimide-based resin (2))

Under a nitrogen gas atmosphere, TFMB was dissolved in DMAc while stirring at room temperature by adding TFMB 45 g (140.52 mmol) and DMAc 768.55 g to a 1 L separable flask equipped with a stirring blade. Next, 6FDA 18.92g (42.58mmol) was added to the flask and stirred at room temperature for 3 hours. Thereafter, 4.19 g (14.19 mmol) of 4,4'-oxybis (benzoylchloride) (OBBC) and then 17.29 g (85.16 mmol) of terephthaloyl chloride (TPC) were added to the flask and stirred at room temperature for 1 hour. Subsequently, 4.63 g (49.68 mmol) of 4-methylpyridine and 13.04 g (127.75 mmol) of acetic anhydride were added to the flask, stirred at room temperature for 30 minutes, heated to 70 ° C using an oil bath, and further stirred for 3.5 hours. The reaction solution was obtained.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread shape, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C to obtain a polyimide resin (2). The weight average molecular weight (Mw) of the polyimide resin (2) was 455,000. Moreover, the imidation ratio of polyimide was 98.9%.

<Production Example 3: Preparation of dispersion 1>

The methanol-dispersed organic-treated silica (particle diameter measured by BET method: 27 nm) was replaced with γ-butyrolactone (GBL) to obtain GBL-dispersed organic-treated silica (solid content: 30.3%). Let this dispersion liquid be dispersion liquid 1.

<Production Example 4: Preparation of varnish (1)>

Varnish 1 had a composition shown in Table 1, and a polymer was dissolved in a solvent to obtain a varnish (1) having a solid content of 15.5% calculated from the amount introduced and a viscosity at 25 ° C of 36,500 cps.

<Production Example 5: Preparation of varnish (2)>

Varnish 2 was mixed with GBL at room temperature so that the composition ratio of the polymer and filler was 60:40, and Sumisorb 340 (UVA) and Sumiplast Violet B (BA) were 5.7 phr or 35 ppm with respect to the total mass of polymer and silica. Add as much as possible and stir until uniform. A varnish (2) having a solid content of 10.3% and a viscosity of 38,500 cps at 25 ° C was obtained.

<Production Example 6: Film formation of raw film (1)>

The varnish (1) was placed on a PET (polyethylene terephthalate) film (Toyobo Co., Ltd. `` Cosmoshine (registered trademark) A4100 '', film thickness 188 μm, film thickness distribution ± 2 μm) The coating film was molded by flexible molding. At this time, the linear velocity is 0.4m / min, and after heating at 70 ° C for 8 minutes, heating at 100 ° C for 10 minutes, followed by heating at 90 ° C for 8 minutes, and finally drying the coating film under heating conditions at 80 ° C for 8 minutes. did. Then, the coating film was peeled from the PET film to obtain a raw 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 film (2)>

The varnish (2) was molded on a PET (polyethylene terephthalate) film (Toyobo Corporation "Cosmoshine (registered trademark) A4100", film thickness 188 μm, film thickness distribution ± 2 μm) by flexible molding. . At this time, the ship speed was 0.3 m / min. Moreover, after heating at 80 degreeC for 10 minutes, it heated at 100 degreeC for 10 minutes, and then heated at 90 degreeC for 10 minutes, and finally, the coating film was dried on condition of heating at 80 degreeC for 10 minutes. Then, the coating film was peeled off from the PET film to obtain a raw film 2 with a thickness of 58 μm and a width of 700 mm. The mass reduction rate M of the raw material film 2 was 9.2%.

<Example 1>

The raw material film 1 obtained in Production Example 6 was used as a gripper to remove the solvent using a tenter dryer (consisting of 1 to 6 rooms) using a clip to obtain a polyimide film 1 having a thickness of 79 μm. The temperature in the dryer was set to 200 ° C, the clip gripping width was 25 mm, the conveying speed of the film was 1.0 m / min, and the ratio of the film width at the dryer outlet to the film width (distance between clips) at the dryer inlet was adjusted to 1.0, and The wind speed in each room of the dryer was adjusted to be 13.5 m / sec in 1 room, 13 m / sec in 2 rooms, and 11 m / sec in 3-6 rooms. After the film fell off the clip, the clip portion was slit, and a PET-based protective film was pasted on the film, and wound up on a 6-inch core made of ABS to obtain a roll film. Table 3 shows the optical properties and residual amount of the obtained film.

<Example 2>

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

<Example 3>

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

<Example 4>

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

<Comparative Example 1>

A polyimide film 5 having a thickness of 48 μm was obtained in the same manner as in Example 2 except that the draw ratio was changed to 1.3. Table 3 shows the optical properties and residual amount of the obtained film.

<Comparative Example 2>

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

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

Claims (10)

A process of gripping both ends of a long strip-shaped transparent resin film comprising at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins, a process of conveying the gripped film, and of the gripped film. The process is such that the ratio of the width of the film after the heat treatment to the width of the film before the heat treatment is 0.96 or more and 1.1 or less by setting the width to a predetermined distance and heat treating the resin film in a dryer, and holding the resin film from the dryer. The manufacturing method of the transparent resin film which has the process of releasing. According to claim 1,
A manufacturing method in which the ratio of the width of the film after heat treatment to the width of the film before heat treatment is 0.96 to 1.0. The method according to claim 1 or 2,
A manufacturing method in which gripping is performed by a plurality of clips. According to claim 3,
A manufacturing method in which a driving device equipped with a clip moves at the same speed as the conveying speed of the film. According to claim 4,
A manufacturing method in which the driving of the driving device is performed by a chain. The method according to claim 1 or 2,
The manufacturing method whose content of the organic solvent contained in the resin film after heat processing is 0.001-3 mass% with respect to the mass of a resin film. The method according to claim 1 or 2,
After releasing the gripping of the film, a manufacturing method having a step of slitting both ends of the film. The method of claim 7,
The manufacturing method which has a process of bonding a protective film to a resin film after slitting a film. The method of claim 8,
After bonding a protective film, the manufacturing method which has the process of slitting the resin film with which the protective film was stuck. The method of claim 8,
The manufacturing method which has the process of winding up a resin film on a roll after bonding a protective film.

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