TW201927872A - Manufacturing method of resin film - Google Patents

Abstract

An objective of the present invention is to improve a drying step of a resin film in order to prevent small scratches on the resin film. The present invention provides a manufacturing method of resin film, wherein, in the step of peeling a resin film obtained by applying a resin varnish on a support from the support and then drying it, the tension applied per unit width of the resin film is 82 N/m or less.

Description

Method for producing resin film

The present invention relates to a method for producing a resin film, and more particularly to a method for producing a transparent resin film having high visibility.

For a transparent member such as a liquid crystal display device or a solar cell device, a transparent resin film may be used. In the transparent resin film, a polyimide film having high heat resistance can be used (Patent Document 1).

Further, when a transparent polyimide film is obtained, a varnish containing a polyimide pigment is applied onto a support, and then the support is peeled off, dried, and a protective layer is laminated.

[Previous Technical Literature] [Patent Literature]

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

However, in the step of drying the polyimide film, the polyimide film is peeled off from the support, dried in a state in which the film is moved, and dried to adhere the protective film to protect the polyimide film. Only in the membrane When moved and dried, very small scratches (such as minor scratches or scratches) that are often difficult to discern are formed on the polyimide film. In the polyimide film, a highly transparent polyimide film which can be used under a bright light source is required to avoid such a flaw.

Therefore, the present invention has been studied in order to prevent such minute scratches, and an object thereof is to improve the drying step of the polyimide film.

In other words, the present invention provides a method for producing a resin film, which is a step of drying a resin film obtained by coating a resin varnish on a support from a support and then drying the resin film. The tension applied per unit width is 82 N/m or less.

The resin varnish preferably contains at least one resin selected from the group consisting of polyimine, polyamidimide, and polyamidamine.

The amount of the residual solvent in the resin film after peeling from the support is 5% by mass or more, and the weight average molecular weight of the resin in the resin varnish is 200,000 to 500,000.

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

In the present invention, by applying a tension of 82 N/m or less per unit width of the resin film in the drying step, it is possible to prevent fine scratches and, in particular, to prevent minute scratches. The transparency of the resin film is improved by not causing minute scratches. Moreover, by preventing small scratches, the diffuse reflection of light is reduced, and when the light is penetrated by a backlight or the like, the backlight can be reduced. Electricity.

1‧‧ ‧ reel

2‧‧‧Protective film take-up reel

3‧‧‧ resin film

4‧‧‧ drying oven

5‧‧‧ Guide roller

6‧‧‧2nd reel

7‧‧‧ Protective film reel

8‧‧‧Moving direction (longitudinal direction)

9‧‧‧ Guide roller

Fig. 1 is a view showing the steps of a manufacturing step of the resin film of the present invention.

Fig. 2 is a view schematically showing the steps of a method for producing a resin film of the present invention.

Figure 3 is a schematic diagram for explaining the tension applied per unit width.

Fig. 4 is a photograph of a resin film having a small number of scratches.

Hereinafter, several embodiments of the present invention will be described in detail using Figs. 1 to 4 . However, the method for producing the resin film of the present invention is not limited to the aspects of Figs. 1 to 4 .

Fig. 1 is a view showing the steps of a manufacturing step of the resin film of the present invention. As described in Fig. 1, the resin film of the present invention is produced by a so-called varnishing, pre-forming film, peeling support, and drying step. 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 applied to the support using a coating device, and after simple drying, the resin is protected. The film is coated on the resin film to temporarily form a laminated film. The laminated film is then transferred to a support peeling step to peel the support without peeling marks. The resin film and the protective film obtained in the peeling step are moved to the drying step of Fig. 1, and the protective film is peeled off while the resin film is dried.

In the varnishing step of Figure 1, it will be as above The resin is dissolved or dispersed in a solvent to form a resin varnish, and the resin used in the production method of the present invention may, for example, be a polyimine-based polymer (including polyimine and polyamidimide). Polyacetamide, polyester, poly(meth) acrylate, cellulose acetate, polyethylene terephthalate, polyethylene naphthalate, copolymers of cyclic olefin polymers and the like. From the viewpoint of excellent transparency, heat resistance, and various mechanical properties, a polyimide-based polymer and a polyamine are preferable, and a polyimide is more preferable. The resin to be contained may be one type or two or more types. The obtained resin film may be a colored or colorless resin film, but is preferably a colorless transparent resin film.

In the present specification, the polyimine is a polymer mainly composed of a repeating structural unit containing a sulfimine group, and the polyamine is a polymer mainly composed of a repeating structural unit containing a guanamine group. The polyimine-based polymer system is a polymer mainly composed of a polyimine and a structural unit containing a quinone group and a structural unit containing a guanamine group.

The polyimine-based polymer of the present invention can be produced by using a tetracarboxylic acid compound and a diamine compound which will be described later as a main raw material, and has a repeating structural unit represented by the formula (10). Wherein G is a tetravalent organic group and A is a divalent organic group. G and/or A are different, and may have two or more structures represented by the formula (10). In addition, the polyimine-based polymer of the present embodiment can contain the formula (11), the formula (12) or the formula without impairing the various physical properties of the obtained polyimide-based polymer film. (13) The configuration shown.

G and G ¹ are a tetravalent organic group, and are preferably an organic group which may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group, and may be exemplified by the formula (20), the formula (21), the formula (22), the formula (23), a group represented by the formula (24), the formula (25), the formula (26), the formula (27), the formula (28) or the formula (29), and a tetravalent hydrocarbon group having 6 or less carbon atoms. Wherein * represents a bonding bond, and 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 an extended aryl group having 6 to 20 carbon atoms which may be substituted by a fluorine atom, and specific examples thereof include a stretching phenyl group.

G ² is a trivalent organic group, preferably an organic group which may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group, and may be exemplified by the formula (20), the formula (21), the formula (22), the formula (23), and the formula (23). 24), any one of the bond bonds of the group represented by the formula (25), the formula (26), the formula (27), the formula (28) or the formula (29) is substituted with a hydrogen atom group and a trivalent A chain hydrocarbon group having 6 or less carbon atoms.

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

A, A ¹ , A ² and A ³ are each a divalent organic group, and are preferably an organic group which may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group, and the following formula (30), formula (31), and formula are exemplified. (32), a group represented by the formula (33), the formula (34), the formula (35), the formula (36), the formula (37) or the formula (38); and the like may be exemplified by a methyl group, a fluorine group, or a chlorine group. a group substituted with a trifluoromethyl group and a chain hydrocarbon group having a carbon number of 6 or less. Wherein * represents a bonding bond, and Z ¹ , Z ² and Z ³ each 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-. 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 -. It is preferred that Z ¹ and Z ² and Z ² and Z ³ are meta or para positions for each ring, respectively.

The polyamine of the present invention is a polymer mainly composed of a repeating structural unit represented by the formula (13). Preferred examples and specific examples are the same as G ³ and A ³ in the polyimine-based polymer. It is also possible to contain a structure represented by the formula (13) in which two or more kinds of G ³ and/or A ³ are different.

The polyimine-based polymer can be obtained, for example, by polycondensation of a diamine and a tetracarboxylic acid compound (tetracarboxylic dianhydride, etc.), for example, according to JP-A-2006-199945 or JP-A-2008- It is synthesized by the method described in 163107. Commercial products of polyimine are, for example, Neopulim manufactured by Mitsubishi Gas Chemical Co., Ltd.

a tetracarboxylic acid compound used in the synthesis of polyimine An aliphatic tetracarboxylic acid compound such as an aromatic tetracarboxylic acid compound such as an aromatic tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride may be mentioned. The tetracarboxylic acid compound may be used singly or in combination of two or more. The tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as a ruthenium chloride compound, in addition to the dianhydride.

Specific examples of the aromatic tetracarboxylic dianhydride include, for example, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 2, 2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyl Tetracarboxylic dianhydride, 3,3',4,4'-diphenylphosphonium tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-double (2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene) Phthalic phthalic anhydride, 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 Anhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic dianhydride, 4,4'-(meta-phenylene dioxygen) Diphthalic dianhydride and 2,3,6,7-naphthalenetetracarboxylic dianhydride. These may be used alone or in combination of two or more.

The aliphatic tetracarboxylic dianhydride may, for example, be a cyclic or acyclic aliphatic tetracarboxylic dianhydride. The cyclic aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2 , cycloalkane tetracarboxylic dianhydride such as 3,4-cyclobutane tetracarboxylic dianhydride and 1,2,3,4-cyclopentane tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7- Alkene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl 3,3'-4,4'-tetracarboxylic dianhydride and these positional isomers. These may be used alone or in combination of two or more. use. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride. These may be used alone or in combination of two or more.

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

In addition, the polyimine-based polymer of the present invention does not detract from the various physical properties of the obtained polyamidene-based polymer film, in addition to the anhydride of the tetracarboxylic acid used in the synthesis of the above polyimine. Further, it may be further reacted with tetracarboxylic acids, tricarboxylic acids, and dicarboxylic acids, and anhydrides and derivatives thereof.

Examples of the tricarboxylic acid compound include an aromatic tricarboxylic acid, an aliphatic tricarboxylic acid, and the like, and a similar chlorochemical compound, an acid anhydride, or the like, and two or more kinds thereof may be used in combination. Specific examples thereof include: 1,2,4-benzenetricarboxylic acid anhydride; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic anhydride and benzoic acid as single bonds, -O-, -CH _a compound in which 2-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ - or a phenyl group is attached.

Examples of the dicarboxylic acid compound include an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, and the like, and a similar ruthenium chloride compound or an acid anhydride, and two or more kinds thereof may be used in combination. Specific examples thereof include terephthalic acid; isophthalic acid; naphthalene dicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; and chains having a carbon number of 8 or less. a dicarboxylic acid compound of the formula hydrocarbon and two benzoic acid with a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ - or benzene a compound attached to the group.

The diamine used for the synthesis of the polyimine may be an aliphatic diamine, an aromatic diamine or a mixture thereof. Further, in the present embodiment, the "aromatic diamine" means a diamine in which an amine group is directly bonded to an aromatic ring, and a part of the structure may contain an aliphatic group or another substituent. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and an anthracene ring, but are not limited thereto. Among these, a benzene ring is preferred. Further, the "aliphatic diamine" means a diamine in which an amine group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be contained in a part of its structure.

The aliphatic diamine may, for example, be an acyclic aliphatic diamine such as hexamethylenediamine, a 1,3-bis(aminomethyl)cyclohexane or a 1,4-bis(aminomethyl) ring. A cycloaliphatic diamine such as hexane, norbornanediamine or 4,4'-diaminodicyclohexylmethane may be used alone or in combination of two or more.

Examples of the aromatic diamine include p-phenylenediamine, meta-phenylenediamine, 2,4-toluenediamine, meta-xylylenediamine, and p-xylylenediamine. An aromatic diamine having one aromatic ring such as 5-diaminonaphthalene or 2,6-diaminonaphthalene; 4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenyl Propane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diamino Diphenylanthracene, 3,4'-diaminodiphenylanthracene, 3,3'-diaminodiphenylanthracene, 1,4-bis(4-aminophenoxy)benzene, 1,3 - bis(4-aminophenoxy)benzene, 4,4'-diaminodiphenylanthracene, bis[4-(4-aminophenoxy)phenyl]anthracene, bis[4-(3 -aminophenoxy)phenyl]anthracene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy) Phenyl]propane, 2,2'-dimethylbenzidine, 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)anthracene, 9,9-bis (4) -amino-3-methylphenyl)anthracene, 9,9-bis(4-amino-3-chlorophenyl)anthracene, 9,9-bis(4-amino-3-fluorophenyl)anthracene An aromatic diamine having two or more aromatic rings may be used alone or in combination of two or more.

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

a polyimide-based polymer and a polyamine which are polymers containing at least one type of repeating structural unit represented by formula (10), formula (11), formula (12) or formula (13), which are diamines, And a tetracarboxylic acid compound (a tetracarboxylic acid compound analog such as a ruthenium chloride compound or a tetracarboxylic dianhydride), a tricarboxylic acid compound (a tricarboxylic acid compound analog such as a ruthenium chloride compound or a tricarboxylic acid anhydride), and a dicarboxylic acid compound. A condensation type polymer of a polycondensation product of at least one compound contained in a group consisting of (a dicarboxylic acid compound analog such as a chloro compound). As the starting material, in addition to the use of the above, a dicarboxylic acid compound (including a ruthenium chloride compound or the like) may be further used. The repeating structural unit represented by the formula (11) is usually derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by the formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound. Specific examples of the diamine and tetracarboxylic acid compound are as described above.

The polystyrene-based polymer and polyamine of the present invention have a weight average molecular weight in terms of standard polystyrene of usually 10,000 to 500,000, preferably 50,000 to 500,000, more preferably 100,000 to 500,000, and still more preferably 200,000 to 500,000, especially 300,000 to 450,000. When the weight average molecular weight of the polyimine-based polymer and the polyamine is in the above range, the filming tends to exhibit high bending resistance, and the viscosity of the resin-containing solution is not excessively high, and the workability is high. It is not easy to reduce the tendency. In the present invention, two or more kinds of polyimine-based polymers or polyimines can be used.

The polyimine-based polymer and the polyamine contain a fluorine-containing substituent to increase the modulus at the time of film formation, and the YI value tends to decrease. When the modulus of elasticity of the film is high, there is a tendency to suppress the occurrence of scratches, wrinkles, and the like. From the viewpoint of transparency of the film, the polyimide-based polymer and the polyamine-based compound preferably have a fluorine-containing substituent. Specific examples of the fluorine-containing substituent include a fluorine group and a trifluoromethyl group.

The content of the fluorine atom in the polyimine-based polymer and the polyamine is preferably 1% by mass or more and 40% by mass or less based on the mass of the polyimine-based polymer or the polyamine. More preferably, it is 5 mass% or more and 40 mass% or less.

The resin varnish may further contain an inorganic material such as inorganic particles in addition to the polyimine-based polymer and/or polyamine.

As the inorganic material, a ruthenium compound such as a quaternary oxide such as cerium oxide particles or tetraethyl ortho-nonanoate may be preferably exemplified, and from the viewpoint of varnish stability, cerium oxide particles are preferred.

The average primary particle diameter of the cerium oxide particles is preferably from 10 to 100 nm, more preferably from 20 to 80 nm. When the average primary particle diameter of the cerium oxide particles is within the above range, the transparency is improved, and the cohesive force of the cerium oxide particles is weakened, so that it tends to be easily handled.

The cerium oxide microparticles of the present invention may be a cerium oxide sol in which cerium oxide particles are dispersed in an organic solvent or the like, and cerium oxide microparticle powder produced by a vapor phase method may be used, but in terms of ease of handling, cerium oxide sol is preferred. .

The average primary particle diameter of the cerium oxide particles in the obtained resin film can be determined by observation by a transmission electron microscope (TEM). The particle size distribution of the cerium oxide particles before the formation of the resin film can be determined by a commercially available laser diffraction type particle size distribution analyzer.

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 still more preferably 20% by mass or more and 50% by mass or less. When the content of the inorganic material is within the above range, it tends to have both transparency and mechanical strength of the resin film.

The resin film may contain other components in addition to the components described above. Other ingredients include, for example, an antioxidant, a release agent, a stabilizer, a blueing agent, a flame retardant, a smoothing agent, and a leveling agent.

The content of the components other than the resin component and the inorganic material is preferably more than 0% by mass and 20% by mass or less, more preferably more than 0% by mass and not more than 10% by mass based on the mass of the resin film.

The resin varnish used in the present invention may be, for example, a polyimide-based polymer and/or polyamine which is obtained by reacting and reacting the above-mentioned tetracarboxylic acid compound, the above-mentioned diamine and the above-mentioned other raw materials. The reaction liquid, the solvent, and the other components used as needed are mixed and stirred to prepare. The reaction solution of the polyimine-based polymer or the like may be changed to a solution using a commercially available polyimine-based polymer or the like, or a commercially available solid polyimide-based polymer.

In the solvent which can be used for the resin varnish, the resin component may be dissolved or dispersed, and examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, and the like. A phthalamide-based solvent; a lactone-based solvent such as γ-butyrolactone or γ-valerolactone; a sulfur-containing solvent such as dimethyl hydrazine, dimethyl hydrazine or cyclobutyl hydrazine; ethylene carbonate or propylene carbonate; A carbonate-based solvent or the like. The amount of the solvent is selected in such a manner that it can be a viscosity which can be treated by the resin varnish, and is not particularly limited. For example, it is usually 70 to 95% by mass, preferably 80 to 90% by mass based on the total of the resin varnish.

The formation of the resin varnish can be produced by mixing the components of the above resin film with a solvent. The mixing is carried out using a general mixing device.

When a resin film containing an inorganic material is produced, an inorganic material is added and 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 is moved to the pre-filming step. In the pre-filming step, the resin varnish is applied to the support by a coating device, and is simply dried, and on the support. A layer of a resin film is formed. The support may be, for example, a resin film substrate or a steel substrate (for example, a SUS conveyor belt). The resin film substrate may, for example, be a polyethylene terephthalate (PET) film. The thickness of the support is not particularly limited, but is preferably 50 to 250 μm, more preferably 100 to 200 μm. A thinner has a tendency to suppress the cost, and a thicker one has a tendency to suppress warpage caused by 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 a protective film is usually further formed on the resin film. The protective film is used to protect the film of the resin film, and a film such as a polyolefin film such as polyethylene or polypropylene or a polyester film such as polyethylene terephthalate can be used. Therefore, in the pre-drying step, a layer of a resin film is formed on the support, and a protective film is further formed on the layer of the resin film to form a laminated film.

The subsequent step of the pre-drying step of Figure 1 is the support stripping step. The support peeling step is a step of peeling the support from the resin film layer without peeling off the mark before the subsequent drying step. The resin film at this point in time has not been subjected to the drying step, so that a plurality of solvent components remain, and the support body must be peeled off very carefully before the drying step, and the support peeling step is provided. The resin film obtained here is composed of two layers of a protective film and a resin film, and is usually wound into a roll shape. The reel may be, for example, a roll of a laminate which is wound around a take-up tube (plastic core, metal roll, or the like) having an outer diameter of 50 to 200 mm to form a laminate. For the take-up tube, a commercially available plastic core of 3 inches in diameter and 6 inches in diameter can be used. In the drying step of Figure 2, the reel can also be used in The take-up reel of the laminated film.

The drying step is specifically shown schematically in Figure 2. The two-layer laminated film of the resin film and the protective film obtained in the previous pre-drying step is shown in the form of the roll 1 in Fig. 2 . In the laminated film sent from the reel 1, the protective film is wound up on the protective film take-up reel 2, and only the resin film 3 is traveled on the plurality of guide rolls 5 in the drying furnace 4. At this time, the surface of the resin film 3 in contact with the guide roller 5 may be any one of the support body surface contacting the support body before the support body is peeled off, or the opposite support body surface of the contactless support body opposite thereto, but the counter support Decent is preferred because of its high hardness. After the guide roller is sufficiently dried in the drying furnace 4 during traveling, it is taken up by the guide roller 9 to the second reel 6. When the second reel 6 is taken up, the protective film is usually sent out from the protective film roll 7 and covered with a protective film. In Fig. 2, the arrow direction indicated by 8 indicates the moving direction (longitudinal direction) of the resin film.

In the present invention, when the tension applied per unit width of the resin film 3 is 82 N/m or less in the drying step, minute scratches can be reduced. In the present specification, the term "tension applied per unit width" means a value obtained by dividing "the tension applied to the moving direction (longitudinal direction) of the resin film" by the "length of the width of the resin film". Use Figure 3 to illustrate the tension applied per unit width. F in Fig. 3 is a tension applied to the moving direction (longitudinal direction) of the resin film, and the unit is N (Newton).

L represents the width of the resin film in a direction perpendicular to the moving direction, and the unit is m (meter). The "tension applied per unit width" is the value of the tension (F) divided by the width (L), F/L (N/m). In the present invention, for each unit width The applied tension is 82 N/m or less, so it must be F/L ≦ 82 N/m. If the tension applied per unit width exceeds 82 N/m, the minute flaws will be better and the transparency will be hindered. The tension applied per unit width is preferably from 30 to 81 N/m, more preferably from 35 to 65 N/m, still more preferably from 40 to 60 N/m. If the tension applied per unit width is too small, there is a fear that other defects such as scratches may occur due to the resin film being meandered in the drying furnace.

In the drying of the drying furnace 4, the coating film may be heated as needed in order to remove the drying of the solvent from the coating film. For example, adjustment may be made such that the heating temperature is in the range of 40 to 240 ° C, and the heating time is in the range of 10 to 180 minutes, preferably 10 to 120 minutes. When it is dried by hot air (removing the solvent), the wind speed of the hot air can be adjusted in the range of 0 to 15 m/sec. When the solvent is removed, the coating film may be heated under an inert gas atmosphere or under reduced pressure. The diameter of the guide rolls in the drying oven 4 is preferably from 10 to 300 mm, more preferably from 30 to 250 mm, still more preferably from 50 to 200 mm. In addition, the surface roughness (Rmax) of the guide roll measured in accordance with 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. When the surface roughness is more than 0.01, the resistance at the time of contact with the resin film becomes small, and if it is less than 1.0, the surface shape of the guide roll is difficult to transfer to the resin film. In addition, the Vickers hardness of the guide roll measured according to 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 roll include nickel plating, electroless nickel plating, nickel-boron plating, hard chrome plating, parkerizing plating, and the like, and preferably, for example, hard chrome plating.

The thickness of the obtained resin film can be appropriately adjusted in accordance with various means for applying the resin film, but is preferably 10 to 500 μm, more preferably 15 to 200 μm, still more preferably 20 to 100 μm. The resin film thus constituted can have particularly excellent flexibility.

In addition, in the present specification, "small scar" refers to light that is irradiated with illuminance of 3,000 lumens or more, for example, 3,400 lumens, from the moving direction of the film (that is, the longitudinal direction), and can be visually recognized as a point defect, and the size refers to It is 40 to 400 μm in size. A photograph of a minute flaw on the surface of the resin film is shown in Fig. 4.

The generation of minute flaws is related to the amount of residual solvent in the resin film in the step after film formation of the resin film. When the amount of the residual solvent in the resin film is large, the surface of the film becomes soft and it is easy to cause minute scratches. The residual solvent in the resin film after the pre-film formation is usually 5 to 30% by mass, preferably about 5 to 20% by mass, based on 100 parts by mass of the resin film, and the amount of the residual solvent after the drying step is usually 0 to 10% by mass, preferably 0 to 5% by mass. If the amount of the solvent remaining after the drying step is considered to be extremely small, the risk of occurrence of minute scratches in the resin film transfer becomes extremely small.

The measurement of the amount of the remaining solvent can be carried out by "TG-DTA measurement". "TG/DTA6300" manufactured by Hitachi Hightech Science Co., Ltd. can be used as the measuring device for TG-DTA. The measurement procedure was as follows: About 20 mg of the sample was obtained from the produced polyimide film.

The sample to be taken is heated from room temperature to 120 ° C at a temperature increase rate of 10 ° C / min, and after holding at 120 ° C for 5 minutes, the sample is heated while heating at a temperature increase rate of 10 ° C / min to 400 ° C. Quality change Chemical.

From the measurement result of TG-DTA, the mass reduction rate T (%) of 120 ° C to 250 ° C was calculated from the following formula as the amount of residual solvent.

T(%)=100-(W ₁ /W ₀ )×100

(In the above formula, W ₀ represents the mass of the sample after holding at 120 ° C for 5 minutes, and W ₁ represents the mass of the sample at 250 ° C.)

In the polyamine-based resin film of the present invention, it is almost impossible to visually recognize minute scratches, and it is excellent for use in optical applications.

Further, the measurement of the weight average molecular weight of the polyimine-based resin and the polyamine was carried out by gel permeation chromatography (GPC) measurement in the following manner.

(1) Pretreatment method

The sample was dissolved in γ-butyrolactone (GBL) to obtain a 20% by mass solution, and then diluted to 100-fold with a N,N-dimethylformamide (DMF) solution, and filtered through a 0.45 μm membrane filter. The resulting one was used as a measurement solution.

(2) Measurement conditions

Device: LC-10Atvp manufactured by Shimadzu Corporation (stock company)

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

Lysate: DMF (addition of 10 mM lithium bromide)

Flow rate: 0.6mL/min

Detector: RI detector

Column temperature: 40 ° C

Injection volume: 20μL

Molecular weight standard: standard polystyrene

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples. However, the invention is not limited to such embodiments.

Example 1

A polyimine ("KPI-MX300F" manufactured by Kawamura Industry Co., Ltd.) having a weight average molecular weight of 360,000 was prepared. This polyimine 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 having a thickness of 188 μm and a width of 900 mm by a casting method at a width of 870 mm to form a film. The film-formed resin varnish was set to a furnace having a length of 12 m and a length of 12° C. at a linear velocity of 0.4 m/min to remove the solvent from the resin solution to form a resin film (thickness: 80 μm). Then, a protective film ("7332" manufactured by Toray Advanced Film Co., Ltd., a polyolefin protective film with weak adhesion) was bonded to the resin film, and the protective film, the resin film, and the PET film were taken up from the roll core. The film-like laminate body is formed into a roll shape (250 m).

The laminate which was wound up in a roll shape was taken up, and the PET film substrate was peeled off, and a laminate composed of a resin film and a protective film was taken up (200 m was obtained).

The laminate which was wound up in a roll shape was wound up under a tension of 30 N (33.3 N/m), and the protective film was peeled off, and the resin film was introduced into a drying furnace at a tension of 80.5 N/m to be further dried. . In the drying furnace, the resin film after peeling off the protective film is brought into contact with the PET film substrate before peeling. The side of the surface (support surface) on the opposite side (reverse support surface) side is conveyed in contact with ten guide rollers, and the guide roller is made of metal having a diameter of 100 mm, a surface roughness (Rmax) of 0.6 S, and Vickers. Hard chrome plated guide roll with a hardness of 850. In the drying furnace, the resin film has a width of 870 mm and a drying furnace tension of 70 N. Therefore, the tension applied per unit width is 80.5 N/n. Further, the temperature of the drying furnace was set to 200 ° C, the conveying speed was set to 0.4 m/min, and the drying time was set to 30 minutes. The resin film which was dried in a drying oven was bonded to a protective film ("7332" manufactured by Toray Advanced Film Co., Ltd., a polyolefin protective film of weak adhesion) on both sides, and wound up on a roll core.

With respect to the dried resin film obtained in Example 1, the protective film on both sides was peeled off, and 1 m was arbitrarily cut out from a 200 m roll, and minute scratches were evaluated as follows.

Evaluation of minor scars

Polarion light [PS-X1" manufactured by Polarion Co., Ltd. (3,400 lumens) was irradiated from the moving direction (ie, the longitudinal direction). At this time, it is irradiated at an inclination angle of about 20 to 70° with respect to the film surface. The direction of visual recognition was evaluated from the human eye from approximately directly above the surface of the resin film to be evaluated (at an angle of 90° from the surface of the resin film). Regarding the area of visual recognition, the four corners are drawn in such a manner as to include all the small scar groups, and the area is added to form the area (the so-called "small scar area"). However, when the four corners are not spaced apart from each other by 0.5 cm or more, the same generation area is set.

The evaluation of small scars is as follows.

○: The area where the micro-scars are visually observed is less than 5% of the total area.

△: The area where the microscopic scar is visually observed is 5% or more of the total area, and is less than 10%.

×: The area where the small scratch is visually observed is 10% or more of the total area.

The micro-scratch of the resin film obtained in Example 1 was evaluated as ○ in the above measurement. The results of Example 1 are shown in Table 1. Table 1 also shows the contact surface with the guide roll, the resin film width (mm), the drying furnace tension (N), the value of the tension (N/m) applied per unit width, and the film evaluation area (cm ² ). The area of tiny scratches (cm ² ) and the proportion of tiny scratches in the whole film (%). In addition, so-called evaluation membrane area (cm ²⁾ area of the film is assessed based minute flaws, the overall percentage of minute flaws film (%) based tiny scar area (cm ²⁾ divided by the membrane area evaluation (cm ²⁾ and multiplied by 100 times.

Determination of residual solvent

The measurement of the amount of residual solvent in the obtained resin film was carried out by "TG-DTA measurement". The order of measurement is as follows: A sample of about 20 mg was taken from the produced resin film.

The sample to be taken was heated from room temperature to 120 ° C at a temperature increase rate of 10 ° C /min, held at 120 ° C for 5 minutes, and then heated to a temperature of 400 ° C at a temperature increase rate of 10 ° C / min. DTA measuring device: The quality change of the sample was measured by "TG/DTA6300" manufactured by Hitachi Hightech Science Co., Ltd.

According to the measurement result of TG-DTA, the mass reduction rate L (%) from 120 ° C to 250 ° C is calculated from the following formula, and this is used as the amount of residual solvent: L (%) = 100 - (W ₁ / W ₀ ) ×100

(In the above formula, W ₀ represents the mass of the sample after holding at 120 ° C for 5 minutes, and W ₁ represents the mass of the sample at 250 ° C). . The amount of residual solvent was measured for each of the resin film before drying and the resin film after drying.

Determination of modulus of elasticity

The obtained resin film was dried at 200 ° C for 20 minutes, and cut into a short mark of 10 mm × 100 mm using a dumbbell cutter to obtain a sample. The elastic modulus of the sample was measured using an autoclave AG-IS manufactured by Shimadzu Corporation, and the S-S curve was measured under the conditions of a jig pitch of 500 mm and a tensile speed of 20 mm/min, and the elastic modulus of the optical film was calculated from the slope. The results are shown in Table 1.

Examples 2 to 8 and Comparative Examples 1 to 2

With respect to the resin film obtained in Example 1, the contact surface of the guide roller in contact with the guide roller (the support surface side/reverse support surface side), the resin film width (mm), the drying furnace tension (N), and the pair The tension (N/m) applied per unit width was changed to as described in Table 1, and after drying, evaluation of minute scratches was performed. The results are shown in Table 1. Table 1 also shows the film evaluation area (cm ² ), the small scratch area (cm ² ), the proportion of minute scratches in the entire film (%), the amount of residual solvent (before drying), and the amount of residual solvent (after drying). And elastic rate.

As is clear from the results of Table 1, when the tension applied per unit width is 82 N/m or less, minute scratches are small and the transparency of the resin film is increased. On the other hand, when the tension applied per unit width exceeds 82 N/m, as seen in Comparative Examples 1 and 2, there are many minute scratches and the transparency of the resin film is deteriorated. Further, the white spot portion shown in Fig. 4 is a minute flaw.

[Industrial availability]

The method for producing a resin film of the present invention can prevent minute scratches (especially minute scratches) by adjusting the tension applied per unit width when drying a transparent resin film. It is widely used in the manufacture of films requiring transparency.

Claims (4)

A method for producing a resin film is a step of applying a resin film obtained by coating a resin varnish on a support to a resin film after peeling the resin film from the support, and applying a tension of 82 N per unit width of the resin film. /m below. The method for producing a resin film according to the first aspect of the invention, wherein the resin varnish contains at least one resin selected from the group consisting of polyimine, polyamidimide, and polyamidamine. The method for producing a resin film according to the first or second aspect of the invention, wherein the amount of the residual solvent in the resin film after the support is removed is 5% by mass or more, and the weight average of the resin in the resin varnish The molecular weight is from 200,000 to 500,000. The method for producing a resin film according to the third aspect of the invention, wherein the amount of the residual solvent in the resin film is 30% by mass or less.