TW201930400A - Method for producing resin film implementing an improvement in the drying process of a resin film in order to prevent small scratches from occurring on the resin film - Google Patents

Abstract

An object of this invention is to implement an improvement in the drying process of a resin film in order to prevent small scratches from occurring on the resin film. This invention provides a method for producing a resin film, which is characterized in that: in the process of drying the resin film that has been coated with a resin varnish on a support body and then peeled off from the support body, the tension applied per unit width of the resin film is 50 N/m or more.

Description

Manufacturing method of resin film

The present invention relates to a method for manufacturing a resin film, especially a method for manufacturing a transparent resin film with high visibility.

As a transparent member of a liquid crystal display device and a solar cell-like element, a transparent resin film may be used. As this transparent resin film, a polyimide film having high heat resistance may be used (Patent Document 1).

In the case of obtaining a transparent polyimide film, after applying a varnish containing polyimide on the support, the support is peeled off and dried, and then a protective layer is deposited.
[Prior Technical Literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 10-310639

[Problems to be solved by the invention]

However, the step of drying the polyimide film is to peel the polyimide film from the support, dry it while moving the film, and attach a protective film to protect the polyimide film after drying, but When the film is moved and dried, very small scars (for example, minute scars or scratches) are usually formed on the polyimide film, which are usually difficult to recognize. Such scratches are in the polyimide film and must be avoided in the polyimide film that requires high transparency when used under a bright light source.

Therefore, the purpose of the present inventors and others is to carry out research in order to prevent the above minor scratches, and to apply improvements in the drying step of the polyimide film.
[Technical means to solve the problem]

That is, the present invention provides a method for manufacturing a resin film, characterized in that in the step of peeling the resin film obtained by coating the resin varnish on the support from the support and then drying, each of the resin films The tension applied per unit width is 50 N / m or more.

The resin solution preferably contains at least one polymer selected from the group consisting of polyimide, polyimide, and imide.

The weight average molecular weight of the resin in the resin varnish is preferably 200,000 to 500,000 or less.

The amount of residual solvent in the resin film after peeling from the support and before the drying step is preferably 5% by mass or more.

The amount of residual solvent in the resin film is preferably 30% by mass or less.
[Effect of invention]

In the present invention, in the drying step, the tension applied per unit width of the resin film is 50 N / m or more, thereby preventing fine scratches, especially scratches. Since no scratches are generated, the transparency of the resin film is improved. Although not limited to a specific theory, it is considered that if the tension applied per unit width exceeds 50 N / m, the resin film does not cause meandering or becomes a meandering meander, which makes it difficult to cause scratches. In addition, since small scratches can be prevented, the diffuse reflection of light is reduced, and the power of the backlight device can also be reduced when the light is transmitted through the backlight device or the like.

Hereinafter, some embodiments of the present invention will be described in detail using FIGS. 1 to 4. However, the manufacturing method of the resin film of the present invention is not limited to the aspect of FIGS. 1 to 4.

FIG. 1 is a process diagram describing the manufacturing process of the resin film of the present invention. As described in FIG. 1, the resin film of the present invention is manufactured through the steps of varnishing, preformed film, peeling of the support, and drying. In the step of varnishing, the resin is dissolved or dispersed in a solvent to form a resin varnish. In the pre-filming step, the obtained resin varnish is coated on the support using a coating device, after simply drying, the protection The film is coated on the resin film to temporarily make a laminated film. The laminated film is then moved to the support peeling step, and the support is peeled off without peeling marks. The resin film and the protective film obtained by the peeling step are moved to the drying step of FIG. 1, the protective film is peeled off, and the resin film is dried.

In the step of varnishing in FIG. 1, the resin is dissolved or dispersed in a solvent as described above to form a resin varnish. Examples of the resin used in the production method of the present invention include polyimide-based polymers ( Contains polyimide and polyimide (imide), polyamide, polyester, poly (meth) acrylate, acetyl cellulose, polyethylene terephthalate, polyethylene naphthalate , Cyclic olefin polymers and copolymers of these. In terms of excellent transparency, heat resistance, and various mechanical properties, polyimide-based polymers and polyamides are preferred, and polyimide is more preferred. The resin contained may be one kind or two or more kinds. The obtained resin film may also be a colored or colorless resin film, preferably a colorless and transparent resin film.

In this specification, the term "polyimide" refers to a polymer mainly composed of repeating structural units containing amide imide groups, and the term "polyamide" refers to a polymer mainly composed of repeating structural units containing amide imide groups. The so-called polyimide-based polymer refers to a polymer mainly composed of a polyimide and a structural unit containing an amide imide group and a structural unit containing an amide group.

The polyimide-based polymer of the present invention can be produced by using the following tetracarboxylic acid compound and diamine compound as main raw materials, and has a repeating structural unit represented by formula (10). Here, G is a tetravalent organic group, and A is a divalent organic group. G and / or A may also include two or more different structures represented by formula (10). In addition, the polyimide-based polymer of the present embodiment may be within the range of various physical properties of the polyimide-based polymer film obtained without damage, including formula (11), formula (12), and formula (13) The structure represented.

[Chem 1]

G and G ¹ are tetravalent organic groups, preferably organic groups which may be substituted by hydrocarbon groups or fluorine-substituted hydrocarbon groups, and examples include formula (20), formula (21), formula (22), and formula (23) ), Formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29), and a tetravalent chain hydrocarbon group having a carbon number of 6 or less. In the formula, * represents a bond, Z represents 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 a C 6-20 arylene group which may be substituted by a fluorine atom, and specific examples include phenylene group.

[Chem 2]

G ² is a trivalent organic group, preferably an organic group that can be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and examples include: formula (20), formula (21), formula (22), formula (23), Any of the bonding bonds of the groups represented by formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29) is substituted with a hydrogen atom and trivalent A chain hydrocarbon group with a carbon number of 6 or less.

G ³ is a divalent organic group, preferably an organic group that can be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group, and examples include: formula (20), formula (21), formula (22), formula (23), In the bonding bonds of the groups represented by formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29), two groups which are not adjacent to each other and are substituted with hydrogen atoms And a chain hydrocarbon group with a carbon number of 6 or less.

A, A ¹ , A ² , and A ³ are all divalent organic groups, preferably organic groups that can be substituted by hydrocarbon groups or fluorine-substituted hydrocarbon groups. Examples are: formula (30), formula (31), formula (32), formula (33), formula (34), formula (35), formula (36), formula (37), or formula (38); the methyl, fluoro, chloro or A group substituted by trifluoromethyl and a chain hydrocarbon group having 6 or less carbon atoms. In the formula, * represents a bonding bond, Z ¹ , Z ² and Z ³ independently represent 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-. As an 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- . Z ¹ and Z ² and Z ² and Z ³ are preferably meta or para with respect to each ring.

[Chemical 3]

The polyamide of the present invention is a polymer mainly composed of repeating structural units represented by formula (13). Preferred examples and specific examples are the same as G ³ and A ³ in the polyimide-based polymer. G ³ and / or A ³ may also include two or more different structures represented by formula (13).

The polyimide-based polymer can be obtained, for example, by polycondensation of a diamine and a tetracarboxylic acid compound (tetracarboxylic dianhydride, etc.). It was synthesized by the method described in 163107. Examples of commercially available products of polyimide include Neopulim manufactured by Mitsubishi Gas Chemical Co., Ltd. and the like.

Examples of the tetracarboxylic acid compound used for synthesizing polyimide 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 also be related to a tetracarboxylic acid compound such as an acetyl chloride compound.

Specific examples of the aromatic tetracarboxylic dianhydride include: 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 2 , 2 ', 3,3'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-biphenyl tetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyl tetra Carboxylic dianhydride, 3,3 ', 4,4'-diphenyl sulfone tetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis ( 2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 '-(hexafluoroisopropylidene) di-ortho Phthalic dianhydride, 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, 4,4 '-(p-phenylene dioxy) diphthalic dianhydride, 4,4'-(m-phenylene dioxy Group) diphthalic dianhydride and 2,3,6,7-naphthalenetetracarboxylic dianhydride. These can be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydride. The cyclic aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure. Specific examples thereof include: 1,2,4,5-cyclohexanetetracarboxylic dianhydride , 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride and other cycloalkane tetracarboxylic dianhydride, bicyclo [2.2.2] octane -7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl 3,3'-4,4'-tetracarboxylic dianhydride and positional isomers of these. These can be used alone or in combination of two or more. Specific examples of the non-cyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butane tetracarboxylic dianhydride, 1,2,3,4-pentane tetracarboxylic dianhydride, etc. These can be used alone or in combination of two or more.

Among the above-mentioned tetracarboxylic dianhydrides, from the viewpoint of high transparency and low colorability, 1,2,4,5-cyclohexanetetracarboxylic dianhydride and bicyclo [2.2.2] octane are preferred 7-ene-2,3,5,6-tetracarboxylic dianhydride and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride.

Furthermore, the polyimide-based polymer of the present invention may be within the range of various physical properties of the polyimide-based polymer film obtained without damage, in addition to the above-mentioned tetracarboxylic acid for synthesizing polyimide In addition to acid anhydrides, those obtained by further reacting tetracarboxylic acids, tricarboxylic acids, dicarboxylic acids, and these anhydrides and derivatives.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and related acetyl chloride compounds, acid anhydrides, and the like, and two or more kinds may be used in combination. Specific examples include: 1,2,4-benzenetricarboxylic acid anhydride; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic anhydride and benzoic acid through a single bond,- O-, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or a compound formed by connecting phenylene groups.

Examples of the dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related acetyl chloride compounds, acid anhydrides, and the like, and two or more kinds may be used in combination. Specific examples include: terephthalic acid; isophthalic acid; naphthalene dicarboxylic acid; 4,4'-biphenyl dicarboxylic acid; 3,3'-biphenyl dicarboxylic acid; chains with a carbon number of 8 or less Dicarboxylic acid compound of the formula hydrocarbon and two benzoic acid via single bond, -O-, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or benzene Compounds formed by linking groups.

As the diamine used for synthesizing polyimide, it can also be an aliphatic diamine, an aromatic diamine or a mixture of these. In addition, in this embodiment, the "aromatic diamine" means a diamine in which an amine group is directly bonded to an aromatic ring, and an aliphatic group or other substituent may be included in a part of the structure. The aromatic ring may be a single ring or a condensed ring, and examples include a benzene ring, a naphthalene ring, an anthracene ring, and a fused ring, but it is not limited thereto. Among these, a benzene ring is preferred. In addition, the "aliphatic diamine" refers to a diamine in which an amine group is directly bonded to an aliphatic group, and may include an aromatic ring or other substituents in a part of its structure.

Examples of the aliphatic diamine include non-cyclic aliphatic diamines such as hexamethylene diamine, 1,3-bis (aminomethyl) cyclohexane, and 1,4-bis (aminomethyl) cyclohexane. Cycloaliphatic diamines such as alkane, noranediamine, 4,4'-diaminodicyclohexylmethane, etc., these can be used alone or in combination of two or more.

Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2 , 6-diaminonaphthalene and other aromatic diamines with an aromatic ring, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-di Amino diphenyl ether, 3,4'-diamino diphenyl ether, 3,3'-diamino diphenyl ether, 4,4'-diamino diphenyl ether, 3,4'-diamine Diphenyl sulfone, 3,3'-diamino diphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene , 4,4'-diaminodiphenyl sulfone, bis [4- (4-aminophenoxy) phenyl] benzene, bis [4- (3-aminophenoxy) phenyl] benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2'-di Methylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 9,9-bis (4-aminophenyl) stilbene, 9,9-bis (4-amino) -3-methylphenyl) stilbene, 9,9-bis (4-amino-3-chlorophenyl) stilbene, 9,9-bis (4-amino-3-fluoro Yl) fluorene and the like aromatic diamine having two or more aromatic rings, these may be used alone, or two or more used in combination.

Among the above diamines, from the viewpoint of high transparency and low colorability, it is preferable to use one or more kinds selected from the group consisting of aromatic diamines having a biphenyl structure. Furthermore, it is preferable to use selected from 2,2'-dimethyl benzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl One or more of the group consisting of 4,4'-diaminodiphenyl ether, and more preferably 2,2'-bis (trifluoromethyl) benzidine.

Regarding the polyimide-based polymer and the polyamide as a polymer containing at least one repeating structural unit represented by formula (10), formula (11), formula (12) or formula (13), it is used as a diamine , Related to tetracarboxylic acid compounds (acetyl chloride compounds, tetracarboxylic acid dianhydrides and other tetracarboxylic acid compounds), tricarboxylic acid compounds (acetyl chloride compounds, tricarboxylic anhydrides and other tricarboxylic acid compounds), and dicarboxylic acids A condensation-type polymer of a polycondensation product of at least one compound contained in a group of compounds (dicarboxylic acid compounds such as acetyl chloride compounds). As a starting material, in addition to these, a dicarboxylic acid compound (including a related compound such as an acetyl chloride compound) may be further used. The repeating structural unit represented by formula (11) is usually derived from diamines 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 a diamine and a dicarboxylic acid compound. Specific examples of the diamine and tetracarboxylic acid compounds are as described above.

In the polyimide-based polymer and polyamide of the present invention, the weight average molecular weight in terms of standard polystyrene is usually 10,000 to 500,000, preferably 50,000 to 500,000, more preferably 100,000 to 500,000, and further preferably 200,000 to 500,000, and more preferably 300,000 to 450,000. The greater the weight-average molecular weight of the polyimide-based polymer and polyamide, the greater the tendency to exhibit higher bending resistance during film formation, but if the polyimide-based polymer and polyamide If the weight average molecular weight is too large, the viscosity of the resin solution will increase and the processability will tend to decrease. Polyimide-based polymers and polyamides can also be used in combination of two or more.

By containing a fluorine-containing substituent, the polyimide-based polymer and the polyamidide tend to increase the modulus of elasticity at the time of filming and decrease the YI value. If the elastic modulus of the film is high, there is a tendency to suppress the occurrence of scars and wrinkles. From the viewpoint of transparency of the film, the polyimide-based polymer and the polyamide preferably have a fluorine-containing substituent. Specific examples of fluorine-containing substituents include fluorine groups and trifluoromethyl groups.

The content of fluorine atoms in the polyimide-based polymer and polyamide is preferably 1% by mass or more and 40% by mass or less, and more preferably 5% by mass relative to the mass of the polyimide-based polymer or polyamide. % By mass or more and 40% by mass or less.

The resin varnish may contain inorganic materials such as inorganic particles in addition to the above-mentioned polyimide-based polymer and / or polyamide.

As the inorganic material, preferably, silicon compounds such as silicon dioxide particles and quaternary alkoxysilane such as tetraethyl orthosilicate are used. From the viewpoint of the stability of the varnish, the silicon dioxide particles are preferably used.

The average primary particle diameter of the silicon dioxide particles is preferably from 10 to 100 nm, and more preferably from 20 to 80 nm. If the average primary particle size of the silica particles is 100 nm or less, the transparency tends to increase. If the average primary particle size of the silica particles is 10 nm or more, the cohesion force of the silica particles is weak, so it tends to become easy to handle.

The silicon dioxide particles used in the present invention may be silica sols made by dispersing the silicon dioxide particles in an organic solvent or the like, or silicon dioxide particle powder manufactured by a gas phase method may be used for easy operation In terms of aspect, silica sol is preferred.

The average primary particle diameter of the silica particles in the obtained resin film can be obtained by observation using a transmission electron microscope (TEM). The particle size distribution of the silica particles before forming the transparent resin film can be obtained by a commercially available laser diffraction particle size distribution meter.

In the resin film of the present invention, the content of the inorganic material is preferably 0% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 60% by mass or less, and further preferably 20% by mass or more and 50% by mass the following. If the blending ratio of the polyimide-based polymer and the polyimide and the inorganic material is within the above range, there is a tendency to easily have both the transparency and mechanical strength of the resin film.

The resin film may contain other components in addition to the components described above. Examples of other components include antioxidants, mold release agents, stabilizers, blueing agents, flame retardants, lubricants, and leveling agents.

The content of the components other than the resin component and the inorganic material relative to the mass of the resin film is preferably more than 0 mass% and 20 mass% or less, more preferably more than 0 mass% and 10 mass% or less.

The resin varnish used in the present invention can be obtained, for example, by reacting a polyimide-based polymer and / or polyamide obtained from the above-mentioned tetracarboxylic acid compound, the above-mentioned diamine and the above-mentioned other raw materials, and reacting them The liquid, the solvent, and the above-mentioned other components used as necessary are mixed and stirred to prepare. It may be changed to a reaction solution such as a polyimide-based polymer, and a solution of a purchased polyimide-based polymer or a solution of a purchased solid polyimide-based polymer may be used.

The solvent used in the resin varnish may be any one that dissolves or disperses the resin component, and examples thereof include amide-based solvents such as N, N-dimethylformamide and N, N-dimethylacetamide. Lactone-based solvents such as γ-butyrolactone and γ-valerolactone, sulfur-containing solvents such as dimethyl ash, dimethyl sulfoxide and cyclobutane, carbonate-based solvents such as ethylene carbonate and propylene carbonate Solvent, etc. The amount of the solvent is selected in such a way as to be the operable viscosity of the resin varnish, so it is not particularly limited. For example, it is 70 to 95% by mass relative to the entire resin varnish, preferably 80 to 90% by mass.

The resin varnish is formed by mixing the components of the resin film in a solvent. The mixing is performed using a general mixing device.

In the case of manufacturing a resin film containing an inorganic material, an inorganic material is added, stirred and mixed to prepare a resin varnish (dispersion liquid) in which the inorganic material is uniformly dispersed.

After the resin varnish is formed, as shown in FIG. 1, it moves to the pre-filming step. In the pre-filming step, the resin varnish is applied to the support by a coating device, and simply dried to form a layer of the resin film on the support. The support is a film-shaped substrate, for example, a resin film substrate or a steel substrate (for example, SUS tape). Examples of the resin film base material include polyethylene terephthalate (PET) film. The thickness of the support is not particularly limited, preferably 50 to 250 μm, more preferably 100 to 200 μm. The thinner case tends to suppress the cost, and the thicker case tends to suppress the curl sometimes generated in the step of removing a part of the solvent.

As described above, in the pre-drying step, a layer of a resin film is formed on the support, but usually a protective film is further formed on the resin film. The protective film is a film for protecting the resin film. Polyolefin-based films such as polyethylene and polypropylene, and polyester-based films such as polyethylene terephthalate can be used. Therefore, in the pre-drying step, a layer formed by forming a resin film on the support and further forming a protective film on the layer of resin film is formed.

The next step below the pre-drying step of FIG. 1 is the support peeling step. The support peeling step is a step of peeling the support from the resin film layer so that the support has no peeling marks before entering the subsequent drying step. The resin film at this point has not yet passed through the drying step, so a large amount of solvent components remain. Before entering the drying step, the support must be particularly carefully peeled off, and this support peeling step is provided. The resin film obtained here includes two layers of a protective film and a resin film, and is usually wound in a roll shape. For example, the roller can be wound around a winding tube (plastic core, metal roller, etc.) with an outer diameter of 50 to 200 mm to form a layered roller. As the coiling tube, commercially available plastic cores of 3 inches and 6 inches in diameter can also be used. This roller can also be used to take up the laminated film in the drying step of FIG. 2.

Specifically, the drying step is schematically shown in FIG. 2. The two-layer laminated film of the resin film and the protective film obtained in the previous pre-drying step is shown in FIG. 2 in the form of a roller 1. The laminated film sent out from the roller 1 winds the protective film on the protective film winding roller 2 and only moves the resin film 3 on the plurality of guide rollers 5 in the drying furnace 4. In this case, the surface of the resin film 3 in contact with the guide roller 5 may be either the surface of the support that is in contact with the support before the above-mentioned peeling of the support, or the opposite of the surface of the anti-support that is not in contact with the support. The support decent is better due to its higher hardness. After fully drying in the drying furnace 4 while moving on the guide roller, it is wound up by the second roller 6 through the guide roller 9. When the second roller 6 is wound up, the protective film is usually sent out from the protective film roller 7 to be covered with the protective film. In FIG. 2, the arrow indicated by 8 indicates the traveling direction (longitudinal direction) of the resin film.

In the present invention, in the above-mentioned drying step, as long as the tension per unit width applied to the resin film 3 is 50 N / m or more, scratches can be reduced. In this specification, the "tension applied per unit width" refers to the value obtained by dividing the tension applied to the direction of travel (longitudinal direction) of the resin film by the length of the width of the resin film. The tension applied per unit width will be described using FIG. 3. F in FIG. 3 is the tension applied in the direction of travel (longitudinal direction) of the resin film, and the unit is N (Newton). L represents the width of the resin film at a right angle to the direction of travel, the unit is m (meter). "Tensile force per unit width" is the value obtained by dividing the tension (F) by the width (L), which is F / L (N / m). In the present invention, the tension applied per unit width is 50 N / m or more, so it must be F / L ≧ 50 N / m. If the tension applied per unit width is less than 50 N / m, the scratches increase, which hinders transparency. The tension applied per unit width is preferably 50 to 150 N / m, more preferably 82 to 150 N / m, and still more preferably 85 to 150 N / m. If the tension applied per unit width is too large, the film width shrinks due to the extension of the film in the direction of travel in the drying furnace, resulting in a problem of reduced production yield after productization. If the tension applied per unit width is less than 50 N / m, a large meander will occur, and scratches will become obvious.
In addition, if the tension is within the above range, the deflection in the direction of travel of the fixed resin film at the time of film transport, in other words, the film meander is small, which is preferable. The meandering width is preferably 5 mm or less, more preferably 1 mm or less, and most preferably 0 mm.

Regarding the drying in the drying furnace 4, the coating film may be heated as necessary in order to remove the solvent from the coating film. For example, the heating temperature can be adjusted in the range of 40 to 240 ° C, and the heating time can be adjusted in the range of 10 to 180 minutes, preferably 10 to 120 minutes. In the case of drying by hot air (removal of solvent), the wind speed of the hot air can be adjusted within the range of 0 to 15 m / sec. When removing the solvent, the coating film can also be heated under an inert environment or under reduced pressure. The diameter of the guide roller in the drying furnace 4 is preferably 10 to 300 mm, more preferably 30 to 250 mm, and still more preferably 50 to 200 mm. In addition, the surface roughness (Rmax) of the guide roller measured according to JIS B0601 is preferably 0.01 or more and 1.0 or less, more preferably 0.03 or more and 0.9 or less, and still more preferably 0.05 or more and 0.7 or less. If the surface roughness is greater than 0.01, the resistance when in contact with the resin film is reduced, and if it is less than 1.0, it is difficult to transfer the surface shape of the guide roller to the resin film, which is preferable. Furthermore, the Vickers hardness of the guide roller measured in accordance with JIS Z2244 is preferably 500 or more and 2,000 or less, more preferably 520 or more and 1,500 or less, and still more preferably 550 or more and 1,300 or less. Examples of the surface treatment method of the metal roller include nickel plating, electroless nickel plating, nickel-boron plating, hard chromium plating, and PARKA plating. Preferably, hard chromium plating is used.

The thickness of the obtained resin film can be appropriately adjusted according to various devices to which the resin film is applied, preferably 10 to 500 μm, more preferably 15 to 200 μm, and still more preferably 20 to 100 μm. The resin film of such a configuration can have particularly excellent flexibility.

Furthermore, in this specification, the term "scratches" refers to irradiating light with an illuminance of more than 3,000 lumens, such as 3,400 lumens, from the width direction (also called "vertical direction") at right angles to the direction of travel of the film, Visually identifiable stripe-shaped defects with a length of 2 to 3 mm. A photograph showing the state of scratches on the resin film is shown in FIG. 4.

The occurrence of scratches is related to the amount of residual solvent in the resin film in the steps after the resin film is formed. If the amount of residual solvent in the resin film is large, the surface of the film becomes soft and easily scratched. The amount of residual solvent in the resin film before the pre-filming is generally 5 to 30% by mass relative to the mass of the resin film, preferably about 5 to 20% by mass, and the amount of residual solvent after the drying step is usually 0 to 10 The mass% is preferably 0 to 5% by mass. It is considered that if the amount of residual solvent after the drying step is the above, the risk of the generation of minute scratches in the conveyed resin film becomes very small.

The measurement of the above-mentioned residual solvent amount is performed by "TG-DTA measurement". As a measurement device for TG-DTA, "TG / DTA6300" manufactured by Hitachi High-Tech Science Corporation can be used. The measurement sequence is as follows:
A sample of about 20 mg was obtained from the produced polyimide film.
The sample taken was heated from room temperature to 120 ° C at a heating rate of 10 ° C / min, and held at 120 ° C for 5 minutes, while heating at a temperature of 10 ° C / min to 400 ° C. On one side, measure the change in mass of the sample.
From the measurement result of TG-DTA, the mass reduction rate T (%) from 120 ° C. to 250 ° C. was calculated by the following formula, and the residual solvent amount was calculated.
T (%) = 100－ (W ₁ / W ₀ ) × 100
(In the above formula, W ₀ represents the mass of the sample held at 120 ° C for 5 minutes,
W ₁ represents the quality of the sample at 250 ℃)

The weight-average molecular weight of the polyimide-based resin and polyamidide is measured by gel permeation chromatography (GPC) and is performed by the following method.
(1) Pretreatment method After dissolving the sample in γ-butyrolactone (GBL) to make a 20% by mass solution, it is diluted to 100 times by the dissolution solution of dimethylformamide (DMF), which will be used The filter of 0.45 μm membrane filter is set as the measurement solution.
(2) Measurement condition device: LC-10Atvp manufactured by Shimadzu Corporation
Column: TSKgel Super AWM-H × 2 + SuperAW2500 × 1 (6.0 mm ID × 150 mm × 3 pieces)
Dissolution solution: DMF (addition of 10 mm lithium bromide)
Flow rate: 0.6 mL / min.
Detector: RI detector column temperature: 40 ℃
Injection volume: 20 μL
Molecular weight standard: standard polystyrene

In the polyamide-based resin film of the present invention, scratches are hardly visually recognized, and they are excellent in optical applications.
[Example]

Hereinafter, the present invention will be described more specifically with examples. However, the present invention is not limited to these embodiments.

Example 1
Polyimide ("KPI-MX300F" manufactured by Kawamura Industries Co., Ltd.) with a weight average molecular weight of 360,000 is prepared. This polyimide was dissolved in a 9: 1 mixed solvent of N, N-dimethylacetamide and γ-butyrolactone to prepare a resin varnish (concentration 20% by mass). The resin varnish was coated on a long strip of polyethylene terephthalate (PET) film substrate with a thickness of 188 μm and a width of 900 mm as a support by a casting method with a width of 870 mm. The resin varnish of the film produced was passed through a furnace with a length of 0.4 m / min at a linear speed of 12 m and a temperature set from 70 ° C to 120 ° C in stages, thereby removing the solvent from the resin varnish to form a resin film (Thickness 80 μm). After that, a protective film ("7332" made by TORAY FILM PRODUCT Co., Ltd., a weakly adhesive polyolefin protective film) is laminated on the resin film, and a film-like laminate composed of the protective film, the resin film and the PET film is rolled Taken from the roller core and made into a roll shape (250 m).

While rolling out the above-mentioned laminated body wound into a roll shape, while peeling off the PET film base material, the laminated body composed of the resin film and the protective film is wound up.

While rolling the above-mentioned laminated body wound into a roll shape with a tension of 30 N (33.3 N / m), the protective film was peeled off, and the resin film was introduced into a drying furnace with a tension of 80.5 N / m to be further dried . In the drying furnace, the resin film after the peeling of the protective film is on the side opposite to the surface (support surface) that is in contact with the PET film substrate before peeling (back support surface) side, and the diameter is 100 mm made of metal , The surface roughness (Rmax) 0.6 S, Vickers hardness of 850 hard chrome plated 10 guide rollers in contact with the way of conveying. In the drying furnace, the resin film width is 870 mm, and the drying furnace tension is 70 N. Therefore, the tension applied per unit width is 80.5 N / m. Furthermore, the temperature of the drying furnace was set at 200 ° C, the conveying speed was set at 0.4 m / min, and the drying time was set at 30 minutes. The resin film dried in a drying furnace is laminated with a protective film on both sides ("7332" manufactured by TORAY FILM PRODUCT Co., Ltd., a weakly adhesive polyolefin protective film), and is wound on a roller core (200 m) .

With respect to the dried resin film obtained in Example 1, the protective films on both sides were peeled off, and 1 m was randomly cut out from a 200 m roller, and scratches were evaluated as described below.
Evaluation of scratches <br/> Polarionlight ["PS-X1" manufactured by Polarion Corporation] (3,400 lumens) is irradiated from the width direction at right angles to the direction of travel. At this time, the film surface is irradiated at a flat angle of about 20 to 70 °. The direction of recognition is approximately directly above the surface of the resin film evaluated (angle of 90 ° from the surface of the resin film), and is evaluated with human eyes. For the area that is recognized, the four corners are drawn in such a way as to include all the minor scar groups, and the area is completed to be regarded as the generation area (called "scratch area"). Among them, when the four corners are not more than 0.5 cm away from the adjacent corners, they are regarded as the same generation area.
The evaluation of scratches is as follows.
◎: The area where the scratches are visualized is less than 5% of the total area
○: The visually generated scratch area is more than 5% of the total area and less than 10%
×: The visible scratch generation area was 10% or more of the total area. The evaluation of the above measurement of the scratches of the resin film obtained in Example 1 was ○. Table 1 shows the results of Example 1. In Table 1, the contact surface with the guide roller, the width of the resin film (mm), the drying furnace tension (N), the value of the tension applied per unit width (N / m), and the scratch area (cm ² ) 1. The overall scratch rate (%) of the film and the presence or absence of film meandering. In addition, the so-called film evaluation area (cm ² ) refers to the area of the film evaluated for scratches, and the overall film scratch ratio (%) is the scratch area (cm ² ) divided by the film evaluation area (cm ² ) and multiplied by 100 By.

Whether the film is meandering is in the transport of the film, the guide roller at the exit of the drying furnace marks the position of the film end when the film is first introduced, and visually confirms the deflection of the end of the film being transported from the above-mentioned mark position To determine the presence or absence of film meandering based on the following criteria.
◎: In the case of 1 mm or less, there is no film meandering 〇: In the case of more than 1 mm and 5 mm or less, there is almost no film meandering ×: In the case of more than 5 mm, there is film meandering

Measurement of the amount of residual solvent <br/> The measurement of the amount of residual solvent in the obtained resin film was performed by "TG-DTA measurement". The measurement sequence is as follows:
A sample of about 20 mg was obtained from the produced resin film.
The sample taken was heated from room temperature to 120 ° C at a heating rate of 10 ° C / min, held at 120 ° C for 5 minutes, and heated while heating to 400 ° C at a heating rate of 10 ° C / min TG-DTA measuring device: "TG / DTA6300" manufactured by Hitachi High-Tech Science Co., Ltd. was used to measure the change in mass of the sample.
Based on the TG-DTA measurement results, the mass reduction rate L (%) from 120 ° C to 250 ° C was calculated by the following formula, and the residual solvent amount was calculated.
L (%) = 100－ (W ₁ / W ₀ ) × 100
(In the formula, W ₀ represents the mass of the sample after being kept at 120 ° C for 5 minutes,
W ₁ represents the quality of the sample at 250 ℃)

Measurement of elastic modulus <br/> The obtained resin film was dried at 200 ° C for 20 minutes, and cut into short strips of 10 mm × 100 mm using a dumbbell cutter to obtain samples. Regarding the elastic modulus of this sample, using an auto-stereograph AG-IS manufactured by Shimadzu Corporation, the SS curve was measured under the conditions of a distance between chucks of 500 mm and a stretching speed of 20 mm / min. Calculate the elastic modulus of the resin film.

In Table 1, in addition to the above scratch evaluation, the contact surface with the guide roller, the width of the resin film (mm), the drying furnace tension (N), the value of the tension applied per unit width (N / m), Membrane evaluation area (cm ² ), scratch area (cm ² ), scratch ratio (%) of the entire film, presence or absence of meanders, residual solvent amount (before drying) and residual solvent amount (after drying).

Examples 2 to 8 and Comparative Examples 1 to 3
For the resin film obtained in Example 1, the contact surface (support surface side / counter support surface side) of the resin film with the guide roller, the width of the resin film, the drying furnace tension, and the application per unit width The tension was changed as described in Table 1, and after drying, the scratch evaluation was performed. The results are shown in Table 1. In Table 1, the contact surface with the guide roller, the width of the resin film (mm), the drying furnace tension (N), the value of the tension applied per unit width (N / m), and scratches are shown in the same manner as in Example 1. Area (cm ² ), scratch ratio (%) of the entire film, presence of meanders, amount of residual solvent (before drying) and amount of residual solvent (after drying).

[Table 1]

As is clear from the results in Table 1, when the tension applied per unit width exceeds 50 N / m, there are fewer scratches and the transparency of the resin film increases. Also, the meandering system does not exist at all or hardly exists. Conversely, if the tension applied per unit width is less than 50 N / m, as seen in Comparative Examples 1 to 3, there are many scratches and the meandering of the resin film can also be seen. In addition, in Examples 1 to 8 and Comparative Examples 1 to 3, the elastic modulus of the obtained resin film was 4.1 GPa. In addition, the white dots shown in FIG. 4 are scratches.
[Industry availability]

The manufacturing method of the resin film of the present invention is to adjust the tension applied per unit width when drying a transparent resin film, thereby preventing small scratches (especially scratches), and can be widely used to require transparency The manufacture of sexual films.

1‧‧‧roll

2‧‧‧Protective film take-up roller

3‧‧‧Resin film

4‧‧‧ drying oven

5‧‧‧Guide roller

6‧‧‧ 2nd roll

7‧‧‧Protection film roller

8‧‧‧ Travel direction (vertical)

9‧‧‧Guide roller

FIG. 1 is a process diagram describing the manufacturing process of the resin film of the present invention.

FIG. 2 is a diagram schematically showing the steps of the method for manufacturing a resin film of the present invention.

FIG. 3 is a schematic diagram illustrating tension applied per unit width.

Fig. 4 is a photograph showing scratches on the resin film.

Claims (6)

A method of manufacturing a resin film, characterized in that, in a step of peeling a resin film obtained by coating a resin varnish on a support after drying from the support, a tension applied per unit width of the resin film is applied Above 50 N / m. The method of manufacturing a resin film according to claim 1, wherein the resin varnish contains at least one polymer selected from the group consisting of polyimide, polyimide amide imide, and polyamide. The method for manufacturing a resin film according to claim 1, wherein the weight average molecular weight of the resin in the resin varnish is 200,000 to 500,000. The method for manufacturing a resin film according to claim 2, wherein the weight average molecular weight of the resin in the resin varnish is 200,000 to 500,000. The method for manufacturing a resin film according to any one of claims 1 to 4, wherein the amount of residual solvent in the resin film after peeling off the support and before the drying step is 5 mass% or more. The method for manufacturing a resin film according to claim 5, wherein the amount of residual solvent in the resin film is 30% by mass or less.