WO2020195377A1

WO2020195377A1 - Resin composition for film, film production method, and film

Info

Publication number: WO2020195377A1
Application number: PCT/JP2020/006595
Authority: WO
Inventors: 石井　英二; 祥吾片野
Original assignee: 富士フイルム株式会社
Priority date: 2019-03-28
Filing date: 2020-02-19
Publication date: 2020-10-01
Also published as: KR102567313B1; CN113646372B; JP7244627B2; TW202102591A; CN113646372A; KR20210134694A; JPWO2020195377A1

Abstract

Provided are: a resin composition which is for a film and from which a film having good haze and/or smoothness can be produced by improving drying-promoting properties, peelability of a support body, and sticking properties between films while suppressing the occurrence of equipment trouble; a film production method; and a film.　This resin composition (dope (21)) for a film contains: a resin (11) having an aromatic ring and/or an imide ring in the main chain thereof, having a glass transition temperature of 170 °C or higher, and being dissolved in a concentration of 10 mass% or more with respect to methylene chloride; a citric acid ester (12) having carboxylic residues and alcohol residues having 3 to 5 carbon atoms; the methylene chloride; and a monovalent alcohol having 1 to 3 carbon atoms.

Description

Resin composition for film, film manufacturing method and film

The present invention relates to a resin composition for a film, a film manufacturing method, and a film.

The resin made of polyarylate or polyimide has an aromatic ring and / or an imide ring in the main chain of the polymer, so that it has heat resistance due to a high glass transition point or excellent mechanical strength. Taking advantage of these characteristics, as an alternative to inorganic glass, applications such as flexible substrates, cover films, and optical compensation films for mobile display materials are being studied. High transparency and smoothness are required for optical applications, and it is desirable to process the resin into a solution film.

These resins have a soluble solvent due to the influence of the ring structure interaction due to the high glass transition point and the large ratio of aromatic ring and / or imide ring in the polymer main chain. , DMF (dimethylformamide) with high boiling point, DMAC (dimethylacetamide), chlorine-based solvent and the like. Of these, in the case of solution film forming, methylene chloride or the like having a low boiling point is suitable from the viewpoint of solvent drying and productivity.

A method for producing a film formed of polyarylate by solution film forming (hereinafter referred to as polyarylate film) is described in, for example, Patent Document 1. In Patent Document 1, by using methylene chloride as a solvent and using a polyarylate resin composition containing a small amount of a specific lower aliphatic alcohol, the releasability of the cast film from the supporting substrate can be improved. It is disclosed.

Japanese Unexamined Patent Publication No. 8-302162

Also in the film manufacturing method by the above-mentioned conventional technique, methylene chloride having a low boiling point is used as a solvent in the solution film forming process. In particular, when a resin design such as imparting a hydrophilic group to the resin is performed in order to enhance the solubility of the resin in methylene chloride, the metal lip which is the resin discharge port of the casting die of the solution film forming apparatus. The resin adheres to the resin and hardens, making it difficult to remove, the required load becomes very high in the process of peeling the film manufactured from the metal support (belt), or the affinity between the resin and methylene chloride is high. As a result, problems such as slow drying of the film after film formation were likely to occur. As a countermeasure to this problem, alcohol was sometimes added. However, the addition of alcohol may further slow down the drying of the solvent or worsen the stickiness of the film.

In view of the above circumstances, the present invention improves the drying acceleration, the peelability of the support, and the sticking property between the films by using a film having good haze and / or smoothness, and suppresses the occurrence of equipment troubles. It is an object of the present invention to provide a resin composition for a film that can be produced, a film production method, and a film.

The present invention for solving the above-mentioned problems of the conventional example is a resin composition for a film, which has an aromatic ring and / or an imide ring in the main chain, and has a glass transition point of 170 ° C. or higher. A resin that dissolves 10% or more in mass percent concentration with respect to methylene chloride, and a citrate ester having a carboxyl residue and an alcohol residue having an alcohol residue in the range of 3 or more and 5 or less carbon atoms. It has methylene chloride and a monohydric alcohol having 1 or more and 3 or less carbon atoms.

The resin is preferably polyarylate or polyimide.

The citric acid ester preferably has a carboxyl residue amount in the range of 0.2 or more and 2.9 or less.

The citric acid ester preferably contains at least one selected from the group consisting of isopropyl citrate, butyl citrate, and pentyl citrate.

The citric acid ester is preferably contained in the range of 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the resin.

The monohydric alcohol is preferably contained in a mass percent concentration of 10% or less with respect to methylene chloride.

It is preferable to contain silica modified with a trimethylsilyl group within the range of 0.005 or more and 0.120 or less of the surface coverage.

Further, the present invention is a method for producing a film, which comprises a casting step of forming a casting film by casting a dope made of the resin composition for a film described above on a metal support. It has a peeling step of forming a film by peeling the casting film from a support, and a drying step of drying the film.

In the casting step, it is preferable that the dope is continuously spread on the traveling support, and in the peeling step, the casting film is continuously peeled from the support.

It is preferable to have a solvent adjusting step of adding a monohydric alcohol to methylene chloride.

In the casting step, a first liquid containing a resin and a citric acid ester and a second liquid containing a resin and silica are used as a dope, and a first layer formed with the first liquid in contact with a support is used. It is preferable to form a casting film including a second layer formed of the second liquid so as to overlap the first layer.

It is preferable that the silica has a surface coverage in the range of 0.005 or more and 0.120 or less and is modified with a trimethylsilyl group.

Further, the present invention is a film, which is a resin having an aromatic ring and / or an imide ring in the main chain, has a glass transition point of 170 ° C. or higher, and has a mass percent concentration of 10% or higher with respect to methylene chloride. A resin to be dissolved, a citric acid ester having a carboxyl residue and an alcohol residue having a carbon number of 3 or more and 5 or less, and a monohydric alcohol having a carbon number of 1 or more and 3 or less. Has.

It is preferable to have silica modified with a trimethylsilyl group on at least one side of the film within a range of 0.2 μm or more and 20 μm or less from the surface and a surface coverage ratio of 0.005 or more and 0.120 or less.

The thickness after drying is preferably in the range of 10 μm or more and 60 μm or less.

According to the present invention, a film having good haze and / or smoothness can be produced by improving drying acceleration, peelability of a support, and sticking property between films, and suppressing the occurrence of troubles to equipment. It is possible to provide a resin composition for a film, a film manufacturing method, and a film.

It is the schematic of an example of a film manufacturing facility. It is sectional drawing of the film. It is the schematic of another example of a film manufacturing facility. It is explanatory drawing of the casting process.

The resin composition for a film of the present invention (hereinafter referred to as a resin composition) includes a resin having an aromatic ring and / or an imide ring in the main chain, a citric acid ester, methylene chloride, and having 1 or more carbon atoms. It has a monohydric alcohol within the following range. Citric acid ester is an additive and methylene chloride and monohydric alcohol are solvents.

The resin having an aromatic ring and / or an imide ring in the main chain (hereinafter referred to as a resin) is preferably a so-called engineering plastic having these rings in the main chain and having excellent mechanical strength or heat resistance. .. Specifically, for example, polyphenylene ether (PPE, Polyphenylene ether), polyarylate (PAR, Polyetherlate), polysulfone (PSF, Polysulfone), polyethersulfone (PES, Polyethersoulene), polyphenylene sulfide (PPS, PPS, PPS, PPS) , Polyetheretherketone (PEEK, Polyetheretherketone), polyimide (PI, Polyimide), polyetherimide (PEI, Polyetherimide) and the like. Among them, polyarylate or polyimide is preferable when used for optical applications because of its excellent transparency.

The polyarylate and polyimide used in the present invention will be described. The polyarylate is an amorphous polyarylate, and specifically, a polycondensate of a dihydroxyl compound having a hydroxyl group directly bonded to an aromatic and a dicarboxylic acid compound having a carboxylic acid group directly bonded to an aromatic. It is a polymer mainly composed of. Such a dihydroxyl compound or a dicarboxylic acid compound can be selected from the viewpoint of methylene chloride solubility, the glass transition point of the resin, or the physical properties or transparency of the film.

Any such polyarylate can be used, but a polyarylate containing a widely used bisphenol residue and aromatic dicarboxylic acid residue can be preferably used. More preferably, it is a polyarylate containing bisphenol A (2,2-bis (4-hydroxylphenyl) propane) and terephthalic acid and / or isophthalic acid. In the polyarylate of the present invention, a copolymer containing two or more kinds of a dihydroxy compound component and / or a dicarboxylic acid compound component is more preferable from the viewpoint of methylene chloride solubility. It is also preferable that the aromatic portion of the dihydroxy compound component and / or the dicarboxylic acid component has a substituent such as a hydrocarbon group, a polar group, or a halogen group.

The molecular weight of the polyarylate used in the present invention is preferably in the range of 10,000 or more and 700,000 or less, and more preferably in the range of 15,000 or more and 500,000 or less in terms of weight average molecular weight. If the molecular weight is 10,000 or less, the strength of the film may not be obtained, and the proportion of molecular ends that tend to be hydrophilic in polyarylate becomes high, so that the metal adhesion of the resin may increase. On the other hand, if the molecular weight is 700,000 or more, it may be difficult to dissolve in methylene chloride. In the present specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC, Gel Permeation Chromatography) analysis.

As the polyarylate as described above, specifically, depending on the physical properties of the film, U Polymer (registered trademark) U-100 or Unitika (registered trademark) M-2000H manufactured by Unitika Ltd. Alternatively, M-2040 or the like can be preferably used. As the polyarylate, a mixture of two or more kinds may be used.

Polyimide is a polymer having an imide bond, and in particular, a polymer containing an imide ring having an imide bond in the repeating unit of the main chain of the polymer. The polyimide is preferably formed from a diamine compound and an acid anhydride compound. As the polyimide, an aromatic polyimide, an alicyclic polyimide, or the like can be used, and these are compounds in which the chemical structure of the portion where the acid anhydride compound and the diamine compound are connected is aromatic or alicyclic. It can be appropriately selected by using it. Aromatic compounds, alicyclic compounds, or their bonds can be replaced with fluorine, hydrocarbons, halogens, hydrophilic groups, or the like. The acid anhydride compound and the diamine compound can be selected from the viewpoint of methylene chloride solubility, the glass transition point of the resin, or the physical properties or transparency of the film. Of these, alicyclic polyimide or fluorine-substituted polyimide is preferable from the viewpoint of methylene chloride solubility, film transparency, and the like.

The polyimide used in the present invention is preferably a resin that is imidized in the state of a resin. As a method for forming a polyimide film, there is a method of forming a polyamic acid obtained by reacting an acid anhydride compound and a diamine compound into a film and imidizing it by heat. However, this method requires high heat treatment and has a large production process load. There is a risk that many of the hydrophilic components of the resin have high metal adhesion, or that insolubilization and coloring are likely to occur after heat treatment, making it difficult to process films for optical applications. It is preferable to use a polyimide resin that is imidized in the state of a resin and has solubility in methylene chloride because a solution-flowable, transparent and smooth film can be obtained.

The molecular weight of the polyimide resin used in the present invention is preferably in the range of 10,000 or more and 700,000 or less, and more preferably in the range of 50,000 or more and 500,000 or less in terms of weight average molecular weight. If the molecular weight is 10,000 or less, the strength of the film may not be obtained, and the proportion of molecular ends that tend to be hydrophilic in the polyimide resin is high, so that the metal adhesion of the resin may be increased. If the molecular weight is 700,000 or more, it may be difficult to dissolve in methylene chloride.

Any such polyimide can be used in the present invention, and for example, pyromellitic anhydride (PMDA, Pyromellitic dianhydride) and 4,4'-diaminodiphenyl ether (ODA, 4,4'-Oxydianiline) can be used. Polyimide synthesized from, or 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, 4,4'-(Hexafluoroisopropylide) diphthical Anhydride) and 2,2'-bis (trifluoromethyl) Examples thereof include polyimide synthesized from -4,4'-diamino-diphenyl (TFMB or TFDB, 2,2'-bis (trifluoromethyl)-[1,1'-biphenyl] -4,4'-diamine). .. More specifically, the above-mentioned polyimide made of 6FDA / TFMB can be preferably used depending on the physical properties of the film and the like. Further, as a commercially available product, Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Company, Inc. or KPI-MX300F manufactured by Kawamura Sangyo Co., Ltd. are preferably mentioned. As the polyimide, a mixture of two or more kinds may be used.

The glass transition point of the resin is 170 ° C or higher. It is preferably 190 ° C. or higher, and more preferably 200 ° C. or higher. When the temperature is 170 ° C. or higher, the heat resistance of the film is high and the coefficient of linear thermal expansion is low, so that it is useful in flexible substrate or cover film applications as a substitute for inorganic glass. When the resin solution is poured onto a support, which will be described later, in solution film formation, the resin concentration of the resin solution increases during the drying process, and the concentration of the resin solution slightly increases due to the high glass transition point of the resin. The molecular motility of the resin is lowered, and the diffusibility of the solvent from the resin solution thereafter is likely to be lowered. However, the resin composition of the present invention can enhance the diffusibility of the solvent in the drying process of the resin solution and promote drying. This is because the effect of preventing the films from sticking to each other is great by suppressing the deterioration of fine irregularities on the film surface due to the delay in drying. Such a drying accelerating effect is particularly large on the air-side surface of the cast resin solution, and is particularly large when a matting agent described later is contained as an effect of preventing the films from sticking to each other. In the present specification, the glass transition point (Tg) is thermomechanical analysis (TMA, Thermo mechanical analysis) using TMA7100 manufactured by Hitachi High-Tech Science Co., Ltd. in accordance with Japanese Industrial Standards JIS K 7121: 2012. It is a value obtained by.

A resin that dissolves 10% or more in mass percent concentration with respect to methylene chloride is preferably used. A resin that dissolves 15% or more is more preferably used, and a resin that dissolves 20% or more is further preferably used. This is because when at least 10% of the resin is dissolved, a smooth film can be obtained in solution film formation.

One type of resin may be used, or two or more types may be used. When two or more kinds are used, for example, the same kind of resin having a different molecular weight or the same kind of resin having a different copolymer composition is appropriately selected from the viewpoint of the solubility or drying property of the solution, or the physical properties or transparency of the film. Can be used.

The resin composition is a dope described later, and the mass ratio of the resin in the entire dope is preferably in the range of 15% or more and 30% or less, and in this example, it is 20%. The mass ratio of the resin in the resin composition is preferably in the range of 8 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the resin composition. It is more preferably 10 parts by mass or more and 30 parts by mass or less, and further preferably 15 parts by mass or more and 25 parts by mass or less. When it is 8 parts by mass or more, the solvent is easily dried in the solution casting of the present invention, and when it is 50 parts by mass or less, the smoothness of the solution-cast film is good.

Methylene chloride is used as a solvent. The solvent is not particularly limited as long as it dissolves the resin, but a solvent containing chlorine in the molecule (hereinafter referred to as a chlorine-based solvent) is preferable. Examples of the chlorine-based solvent that can be used include methylene chloride, chloroform, 1,2-dichloroethane, and 1,1,2,2-tetrachloroethane, and in this example, methylene chloride is used. In the case of chlorine-based solvents, especially in the case of methylene chloride, it can be used alone as a solvent without using other solvent components in combination, and in this example as well, only methylene chloride is used as the solvent. Since methylene chloride, which is a chlorine-based solvent, is used as the solvent, the resin dissolves in the solvent in a mass ratio sufficient for doping even at room temperature. Since the resin has good solubility, a film having excellent transparency can be obtained.

Add a monohydric alcohol having a carbon number of 1 or more and 3 or less to methylene chloride. As such a monohydric alcohol, methanol, ethanol, 1-propanol or the like can be used. Preferably, methanol is used. By adding a monovalent alcohol, especially when a film is prepared by a solution film forming method, when the dope made of the resin composition adheres to the metal lip of the casting die and hardens, it is extremely difficult to remove the film. There is a problem of sticking that causes surface failure such as streaks, or the load required in the process of peeling the film from the metal support (belt) that spreads the dope becomes very high. The problem of stripping is improved.

The mixing ratio of the monohydric alcohol to the methylene chloride is preferably in the range of 0.5% or more and 10% or less in terms of mass ratio with respect to the total solvent containing the methylene chloride and the monohydric alcohol. More preferably, it is 1% or more and 5% or less, and further preferably 1% or more and 3% or less. Within this range, the transparency of the film in which the solution is cast is good. In the present invention, the monohydric alcohol added as a solvent can be measured as the amount of residual solvent in the film.

Next, the citric acid ester will be described. The citric acid ester used in the present invention is represented by the following general formula (1). In the formula (1), R ¹ , R ² and R ³ are independently hydrogen (H) or a hydrocarbon group having 3 or more and 5 or less carbon atoms, and R ⁴ is hydrogen (H). ), A carbonyl group, or an acetyl group. The citric acid ester of the present invention contains at least a component in which R ¹ is hydrogen (H).

Such a citric acid ester can be obtained, for example, by a partial esterification reaction of citric acid or a partial hydrolysis reaction of a trisubstituted ester of citric acid. R ² and R ³ are residues of the compound used in the partial esterification reaction of citric acid or the partial hydrolysis reaction of the trisubstituted ester of citric acid. Therefore, R ² and R ³ contain at least alcohol residues. Therefore, the citric acid ester of the present invention contains a carboxyl residue and an alcohol residue.

In the reaction of these citric acid esters, the number of carboxyl residues does not necessarily have to be 1, 2, or 3, and the above partial esterification or partial hydrolysis provides the carboxyl residues of citric acid. You just have to. The number of carboxyl residues is preferably in the range of 0.2 or more and 2.9 or less, more preferably in the range of 0.3 or more and 2.0 or less, and particularly preferably 0, as the average value of all the additives used. It is within the range of .5 or more and 1.5 or less. The number (amount) of carboxyl residues of the citric acid ester is determined by, for example, the acid value of a chemical product according to Japanese Industrial Standard JIS K0070-1992, and the measured value of the acid value is mg (KOH) / g ( (Chemical product), it can be obtained by a method such as converting to the amount of carboxyl residue of the additive.

As described above, the citric acid ester is, in detail, a mixture of various compounds. The main compounds include the following. For example, at least one of R ¹ , R ² , and R ³ forms a carboxylic acid group, and at least one of R ¹ , R ² , and R ³ has a carbon number of 3 or more and 5 or less. It is a hydrocarbon group of.

More specifically, in the formula (1), R ¹ , R ² and R ³ are independently n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl group and sec. -A pentyl group or an isopentyl group, more preferably an isopropyl group, a sec-pentyl group, or an n-butyl group, and particularly preferably an isopropyl group. In addition, in this specification, a trivial name is also used for a compound, n- represents a normally, and sec- represents a secondary.

As an example of the citrate ester, in the formula (1), R ¹ and R ⁴ are hydrogen (H), R ² and R ³ are isopropyl groups, and isopropyl citrate, R ¹ and R ⁴ are hydrogen (H). , R ² and R ³ are n-butyl groups, butyl citrate, R ¹ and R ⁴ are hydrogen (H), R ² and R ³ are sec-pentyl groups, sec-pentyl citrate and the like. Be done. Among these, isopropyl citrate represented by the following formula (2) is preferable.

The number of carboxyl residues contained in the citric acid ester is at least one, and when the number is at least one, the produced film has good peelability from the support and adhesion to the metal lip. This is because the carboxyl residue of the citric acid ester is present in the oxide film on the surface of the support when the film is manufactured using a support made of SUS (Steel Use Stainless, stainless steel), for example, as described later. It is presumed that this is because it has an action of cutting off or weakening the interaction between the hydroxyl group and the resin.

The citric acid ester has at least one alcohol residue having 3 to 5 carbon atoms, and by having at least one alcohol residue, drying is promoted and a smooth film can be obtained. Alcohol residues having 3 to 5 carbon atoms prevent the casting film and the film from drying, so that the unevenness generated on the film surface and the film surface due to, for example, the surrounding air flow or the wind is further suppressed.

One type of citric acid ester may be used, or two or more types may be mixed and used. When two or more types are mixed, it is recommended to use the citric acid ester which is a mixture by hydrolysis of the citric acid ester, so that the film can be peeled off from the support and promote drying while maintaining the transparency of the film when mixed. Is preferable because Further, as the citric acid ester, a commercially available one may be used. As a commercially available product, isopropyl citrate (mixture) (Isopropanol City (mixture)) manufactured by Tokyo Kasei Co., Ltd. can be used.

The mass ratio of the citric acid ester is preferably in the range of 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the resin, and is also within this range in this example. When the mass ratio of the citric acid ester is 0.01 parts by mass or more, the film has a smoother film surface with better peelability from the support than when it is less than 0.01 parts by mass. When the mass ratio of the citric acid ester is 10 parts by mass or less, the white turbidity is further suppressed and the haze (cloudiness) is good and the transparent film is obtained as compared with the case where the mass ratio exceeds 10 parts by mass. The mass ratio of the citric acid ester is more preferably in the range of 0.05 parts by mass or more and 5 parts by mass or less. The mass ratio of the citric acid ester in the film is substantially the same as the mass ratio of the citric acid ester in the resin composition for film (dope 21 (see FIG. 1) described later).

As described above, by using the citric acid ester as an additive, drying is promoted and the adhesiveness between the films is improved even when alcohol is added while suppressing the decrease in haze due to the additive. Will be done.

The resin composition contains various additives such as a plasticizer, an ultraviolet absorber, fine particles, and a deterioration inhibitor in addition to adding the resin and the citric acid ester to the solvent composed of methylene chloride and monohydric alcohol. It may be. Further, a known peeling accelerator (also referred to as a peeling reducing agent or the like) for improving the peelability may be contained as an additive.

As the additive, it is preferable to add a matting agent which is fine particles. The matting agent is an additive for improving the slipperiness of the surface of the film. An example of functioning as a matting agent is fine particles of silica (SiO ₂ ). The matting agent also contributes to the improvement of peelability from the support described later.

The silica fine particles are preferably fine particles whose surface has been modified (modified) by a TMS (trimethylsilyl) group. The surface modification is a hydrophobizing treatment, and silica fine particles are treated with HMDS (hemethyldisilazane, hexmethyldisilazane), TMCS (Trimethylsilyl chloride, trimethylchlorosilane) or the like, as is usually performed. As a result, the silanol groups on the surface of the silica are trimethylsilylated and the hydrophobic groups are introduced, so that the hydrophobization treatment is performed. The surface coverage of the trimethylsilyl group in silica is preferably in the range of 0.005 or more and 0.120 or less. More preferably, it is in the range of 0.008 or more and 0.050 or less, and further preferably, it is in the range of 0.012 or more and 0.030 or less. When the surface coating ratio is in the range of 0.005 or more and 0.120 or less, scattering of the surface can be suppressed, transparency can be ensured, and adhesion between films can be suppressed, which is preferable.

The surface coverage is obtained by dividing the carbon content in the fine particles by the specific surface area. That is, the surface coverage is determined by RC / S when the carbon content of the fine particles is RC and the specific surface area is S. The carbon content RC is determined by elemental analysis by the combustion method (for example, a fully automatic elemental analyzer manufactured by Perkin Elmer Japan Co., Ltd.). The specific surface area S is measured according to the BET method (adsorption theory method by Brunauer, Emmett, and Teller). The specific surface area of the silica fine particles is preferably in the range of 20 m ² / g or more and 400 m ² / g or less, more preferably in the range of 50 m ² / g or more and 300 m ² / g or less, 70 m ² / g or more and 150 m. It is particularly preferably in the range of ² / g or less. Within this range, transparency can be ensured as the particle size of the silica fine particles, and adhesion between the films can be suppressed, which is preferable.

Next, the film manufacturing method will be described. The method for producing a film includes a casting step, a peeling step, and a drying step. In the casting step, a dope made of a resin composition for a film is cast on a metal support to form a casting film. In the peeling step, a film is formed by peeling the casting film from the support. In the drying step, the film is dried.

The film manufacturing facility 20 shown in FIG. 1 is an example of a facility for manufacturing the film 10, and a film manufacturing method will be described using this example. The film manufacturing facility 20 includes a dope preparation device 22 and a film manufacturing device 23. The dope preparation device 22 is for preparing the dope 21 which is a resin composition for a film. The dope preparation device 22 includes a mixing tank 26, a pump 27, a filter 28, a storage tank 31, and a pump 32, which are connected by a pipe 33 in this order from the upstream side.

The mixing tank 26 is for dissolving the resin 11 and the citric acid ester 12 in the solvent 15 by mixing the resin 11 which is the raw material of the dope 21, the citric acid ester 12, and the solvent 15. First, the solvent 15 is adjusted by mixing methylene chloride and methanol, which is a monohydric alcohol, in the mixing tank 26 (solvent adjustment step). The resin 11 and the citric acid ester 12 are added to the mixing tank 26 containing the solvent 15.

The resin 11 supplied to the mixing tank 26 is a powder in this example, but the mode of the resin 11 is not limited to powder, and may be, for example, flakes or pellets. The mixing tank 26 is provided with a stirring mechanism (not shown) for stirring the guided mixture of the resin 11, the citric acid ester 12, and the solvent 15, thereby promoting dissolution. The stirring mechanism of this example is a stirring blade housed in a mixing tank and a driving unit that rotationally drives the stirring blade. However, the stirring mechanism is not particularly limited as long as it is a mechanism for stirring a mixture of the resin 11, the citric acid ester 12, and the solvent 15. The resin 11 and the citric acid ester 12 are dissolved in the solvent 15 by being mixed with the solvent 15 in the mixing tank 26 to form the dope 21. Since the citric acid ester 12 has excellent solubility in the solvent 15 and also has excellent compatibility with the solution in which the resin 11 is dissolved in the solvent 15, a film 10 having excellent transparency can be obtained.

It is also preferable that the resin 11 supplied to the mixing tank of the present invention is heat-dried before being supplied to reduce the water content of the resin. The resin of the present invention may absorb moisture. For polyarylate, the water content of the resin is within the range of 1% or more and 2% or less with respect to the entire resin, and for polyimide, the water content is within the range of 2% or more and 4% or less. It may be about%. If the solution is prepared while the water content of the resin 11 is high, the solution may become cloudy or the transparency of the film may deteriorate, and the fluctuation of the water content of the resin may cause fluctuations in the resin concentration, drying during casting, or Peelability may vary. The heating and drying of the resin 11 of the present invention preferably has a heating temperature in the range of 100 ° C. or higher and 180 ° C. or lower, and more preferably 120 ° C. or higher and 160 ° C. or lower. The heating time is preferably in the range of 5 minutes or more and 240 minutes or less, and more preferably in the range of 20 minutes or more and 180 minutes or less. The water content of the resin after heat-drying is preferably 1% or less, more preferably 0.7% or less.

The mixing tank 26 may be provided with a temperature control mechanism (not shown) for adjusting the internal temperature. The mixing tank 26 of this example also has a temperature control mechanism, and maintains the temperature of the mixture at room temperature (generally within the range of 25 ° C. or higher and 30 or lower). Depending on the type of the resin 11, the citric acid ester 12, and the solvent 15 used, the temperature of the mixture is adjusted by the temperature control mechanism, so that dissolution is promoted and alteration and / or foaming is suppressed. For example, when methylene chloride is used as the solvent 15, the temperature is preferably 39 ° C. or lower under normal pressure, whereby foaming is suppressed. When methylene chloride is used as the solvent 15, the temperature in the mixing tank 26 is more preferably in the range of 15 ° C. or higher and 39 ° C. or lower, further preferably in the range of 15 ° C. or higher and 37 ° C. or lower, and 25 ° C. or higher and 35 ° C. or lower. The range of is particularly preferable. However, depending on the type of the resin 11, the citric acid ester 12, and the solvent 15 used, the resin 11 may be dissolved without adjusting the temperature. In that case, the temperature control mechanism may not be provided.

When the above-mentioned various additives are contained in the film 10, these additives may be guided to the mixing tank 26. As described above, the raw materials of the dope 21 mixed with the mixing tank 26 are not limited to the resin 11, the citric acid ester 12, and the solvent 15.

Depending on the raw material, impurities may be mixed in, or it may not be dissolved by stirring in the mixing tank 26 and may remain as an insoluble matter. Therefore, in this example, the dope 21 is sent from the mixing tank 26 to the filter 28 by the pump 27, and these foreign substances are removed by the filter 28. As the filter 28, a filter paper having a pore diameter of 20 μm (63LS manufactured by Toyo Filter Paper Co., Ltd.) is used, but the pore diameter and the material are not limited to this example, and the application of the film 10 or the resin 11 and the citric acid ester 12 are used. It may be determined according to the type of the solvent 15 and the like. The pore size of the filter paper used as the filter 28 is preferably in the range of 5 μm or more and 100 μm or less, more preferably in the range of 10 μm or more and 50 μm or less, and further preferably in the range of 10 μm or more and 25 μm or less.

Examples of other filters include metal filters, and the pore diameter of the metal filter is preferably in the range of 3 μm or more and 15 μm or less, more preferably in the range of 3 μm or more and 10 μm or less, and further preferably in the range of 3 μm or more and 5 μm or less. When a metal filter having such a pore size is used, a metal filter may be arranged downstream of the filter 28 and filtered in two stages. Such stepwise filtration is particularly effective in producing optical films.

A heater (not shown) may be provided between the pump 27 and the filter 28, and the heater may promote the dissolution of the undissolved portion that was not dissolved in the mixing tank 26. Further, depending on the type of the resin 11 used, it may be difficult to dissolve in the solvent 15, and a heater may be used in such a case as well. For example, when methylene chloride is used as the solvent 15, the temperature of the dope 21 in the heater is more preferably in the range of 40 ° C. or higher and 120 ° C. or lower, further preferably in the range of 45 ° C. or higher and 90 ° C. or lower, and more preferably 60 ° C. The range of 90 ° C. or lower is particularly preferable.

The dope 21 that has been filtered by the filter 28 is guided to the storage tank 31 and stored in the storage tank 31 until it is subjected to casting. The storage tank 31 preferably includes a stirring mechanism (not shown), and this example also includes a stirring mechanism having the same configuration as the stirring mechanism of the mixing tank 26. This stirring mechanism more reliably maintains the uniformity of the dope 21 until it is subjected to casting. In this example, the number of storage tanks 31 is one, but it may be a plurality. In the case of a plurality of storage tanks 31, a plurality of storage tanks 31 may be connected in series or in parallel.

It is preferable that the mixing tank 26, the filter 28, and the storage tank 31 are each provided with a light-shielding member that shields light from the inside, and this is also provided in this example. For example, in the mixing tank 26, the tank main body for accommodating the mixture is formed of a material having a light-shielding function, and the upper portion of the tank main body is provided with a lid as a light-shielding member also having a light-shielding function. ing. With such a light-shielding member, when polyarylate is used as the resin 11, the fleece transition of the polyarylate is suppressed. In order to further suppress the Fries rearrangement of polyarylate, it is preferable that all the devices and members constituting the film manufacturing facility 20 are provided with a light shielding mechanism. Further, it is preferable to put the raw material polyarylate in a container having a light-shielding function, such as a light-shielding bag or a light-shielding can, in order to suppress fleece transfer even during storage until the raw material polyarylate is provided in the mixing tank 26. Since the above-mentioned ultraviolet absorber has a function of suppressing Fries rearrangement, it is preferable to use it as an additive.

The downstream end of the pipe 33 is connected to the casting die 36 of the film manufacturing apparatus 23, and the dope 21 of the storage tank 31 is sent to the casting die 36 by the pump 32. In the case of producing the film 10 having a single layer structure, the dope 21 to be cast is preferably in the range of 15% or more and 30% or less in terms of mass percent concentration, and 20% in this example. I have to. When it is set to 15% or more, the viscosity of the dope (corresponding to the pressure loss (pressure loss)) of the dope emitted from the casting die 36 is more likely to be secured than in the case of less than 15%. Further, by setting the content to 30% or less, when the solvent 15 is methylene chloride, the resin 11 is more reliably dissolved in the solvent 15 and the dope 21 becomes more cloudy than when it is larger than 30%. It is surely prevented.

In the case of producing the film 10, when the resin 11 is polyarylate, the concentration of the polyarylate is more preferably in the range of 15% or more and 25% or less in terms of mass percent concentration, and 15% or more and 23%. It is more preferably within the following range. Even if the polyarylate concentration is in the range of 8% or more and less than 15%, the dope 21 can be cast by using, for example, a gisa (preferably G-type gisa). When the resin 11 is polyimide, the concentration of polyimide is more preferably in the range of 20% or more and 30% or less in terms of mass percent concentration.

The concentration of the resin 11 can be adjusted by adjusting the supply amounts of the solvent 15 and the resin 11 supplied to the mixing tank 26. The concentration of the resin 11 in the dope 21 is a mass percent concentration, which is the mass ratio of the resin 11 to the mass sum of the resin 11 and the solvent 15. That is, when the mass of the solvent 15 is M15 and the mass of the resin is M11, it is calculated by {M11 / (M15 + M11)} × 100.

The mass percent concentration of the citric acid ester 12 with respect to the dope 21 is preferably in the range of 0.1% or more and 10% or less, and is also within this range in this example. The mass percent concentration of the citric acid ester 12 in the dope 21 is more preferably in the range of 0.5% or more and 5.0% or less.

The film manufacturing apparatus 23 manufactures the film 10 from the dope 21. The casting unit 37, the tenta 38, the roller dryer 41, the slitter 42, and the winder 43 are provided in this order from the upstream side. The casting unit 37 includes a belt 46 as a support formed in an annular shape, a pair of rollers 47 that run in the longitudinal direction while supporting the belt 46, a casting die 36, and a stripping roller 48. Be prepared. At least one of the pair of rollers 47 is rotated in the circumferential direction by a drive mechanism (not shown), and this rotation causes the belt 46 wound around the pair of rollers 47 to circulate in the longitudinal direction. The casting die 36 is arranged above one of the pair of rollers 47 in this example, but may be arranged above the belt 46 between one and the other of the pair of rollers 47.

The casting die 36 is a discharge unit that continuously discharges the supplied dope 21 from the discharge port 36a facing the belt 46. By continuously discharging the dope 21 to the running belt 46, the dope 21 is cast on the belt 46, and the casting film 51 is continuously formed on the belt 46 (casting step). In FIG. 1, a reference numeral PC is attached to a position where the casting film 51 starts to be formed (hereinafter, referred to as a casting position) when the dope 21 comes into contact with the belt 46. The material of the belt 46 is not particularly limited, but metal is preferable, and in this example, the above-mentioned SUS is used.

The pair of rollers 47 includes a temperature controller (not shown) for adjusting the peripheral surface temperature. The temperature of the casting film 51 is adjusted via the belt 46 by the roller 47 whose peripheral surface temperature is adjusted. In the case of the so-called dry gelling method in which drying is promoted by heating the casting film 51 and then hardened (gelled) by this drying, the peripheral surface temperature of the roller 47 is, for example, in the range of 10 ° C. or higher and 30 ° C. or lower. To be inside. Further, in the case of the so-called cooling gelation method in which the casting film 51 is hardened by cooling, the peripheral surface temperature of the roller 47 is set within the range of −15 ° C. or higher and 5 ° C. or lower. Due to such gelation, the casting film 51 hardens to the extent that it can be conveyed.

A drum (not shown) may be used as the support instead of the belt 46. In this case, a drive mechanism is provided on the drum, and the drum is rotated in the circumferential direction to form the casting film 51 on the peripheral surface. In this case, the peripheral surface of the drum functions as the surface of the traveling support. The material of the drum is not particularly limited, but a metal is preferable, and the metal is preferably SUS, particularly SUS plated with hard chrome. When the drum is used as a support, the drum shall be provided with a temperature controller (not shown) for adjusting the peripheral surface temperature, and the temperature of the casting film 51 may be adjusted by adjusting the peripheral surface temperature of the drum. It is good to do. In the case of the dry gelation method, it is preferable to use the belt 46 as the support, and in the case of the cooling gelation method, it is preferable to use the drum as the support.

Regarding the dope 21 from the casting die 36 to the belt 46, the so-called bead, a decompression chamber (not shown) may be provided upstream of the belt 46 in the traveling direction, and is also provided in this example. This decompression chamber sucks the atmosphere of the upstream area of the discharged dope 21 and decompresses this area by this suction. Further, a blower (not shown) for promoting the drying of the casting film 51 may be provided at a position facing the belt 46.

The casting film 51 is hardened on the belt 46 to the extent that it can be conveyed to the tenta 38, and then continuously peeled off from the belt 46 in a state containing a solvent. As a result, the film 10 is formed (peeling step). The stripping roller 48 is for continuously stripping the casting film 51 from the belt 46. The stripping roller 48 supports the film 10 formed by peeling from the belt 46, for example, from below, and holds the stripping position PP in which the casting film 51 is peeled off from the belt 46 at a constant level. The peeling method may be either a method of pulling the film 10 to the downstream side, a method of rotating the peeling roller 48 in the circumferential direction, or the like.

Since the dope 21 contains a monohydric alcohol and a citric acid ester 12, the casting film 51 formed on the belt 46 also contains the citric acid ester 12. And the citric acid ester 12 has a carboxyl residue. Therefore, from the above-mentioned presumed action on the interaction between the hydroxyl group on the surface of the belt 46 and the resin 11, the peeling load from the belt 46 is suppressed to be small, and as a result, the casting film 51 is smooth (smooth). ) Is continuously peeled off from the belt 46. Therefore, a film 10 having excellent smoothness on the film surface can be obtained. Since the film surface is smooth, a film 10 that can be used for an optical film having strict requirements for optical characteristics can be obtained. Further, when the number of carboxyl residues of the citric acid ester 12 of this example is two, the peeling load can be suppressed to be smaller than that of one case.

The mass ratio of the citric acid ester 12 is almost equal between the dope 21 and the casting film 51. Therefore, also in the casting film 51, the mass ratio of the citric acid ester 12 is in the range of 0.01 parts by weight or more and 10 parts by weight or less when the resin 11 is 100 parts by weight. When the amount is 0.01 parts by mass or more, the peeling load from the belt 46 can be suppressed to be smaller more reliably than when the amount is less than 0.01 parts by mass. Further, when the amount is 10 parts by mass or less, the transparent film 10 has more suppressed white turbidity than the case where the amount exceeds 10 parts by mass.

In the case of the dry gelation method, the stripping from the belt 46 is performed, for example, while the solvent content of the casting film 51 is in the range of 10% by mass or more and 100% by mass or less. In the present specification, the solvent content (unit:%) is a value based on the dry amount. Specifically, when the mass of the solvent 15 is M15 and the mass of the film 10 is M10, {M15 / (M10-M15)} × 100 is the percentage calculated. In the case of the cooling gelation method, the stripping is performed while, for example, the solvent content of the casting film 51 is in the range of 100% by mass or more and 300% by mass or less.

Since the casting film 51 contains a monohydric alcohol and a citric acid ester 12, and the citric acid ester 12 has a carboxylic acid group and a hydrocarbon group, drying is stopped and the time required for peeling is shortened. .. This drying promoting action appears as a more remarkable action as it is closer to the belt 46 in the thickness direction of the casting film 51. Therefore, this drying promoting action and the above-mentioned presumed action on the interaction between the hydroxyl group on the surface of the belt 46 and the resin 11 are combined, and the peeling load of the casting film 51 from the belt 46 can be suppressed to be smaller. Further, since the running speed of the belt 46 can be further increased by the drying promoting action, the manufacturing efficiency of the film 10 is also improved. Furthermore, since the belt 46 can be made shorter due to the drying promoting action, the casting unit 37 can be downsized.

As described above, the casting unit 37 forms the film 10 from the dope 21. The belt 46 circulates between the casting position PC and the stripping position PP, so that the dope 21 is cast and the casting film 51 is stripped repeatedly.

A blower (not shown) for promoting the drying of the film 10 may be arranged in the transport path between the casting unit 37 and the tenta 38. The film 10 formed by peeling off is guided by the tenta 38. The tenta 38 includes a clip 52 that grips a side portion of the long film 10, a pair of rails (not shown), and a chain (not shown). Instead of the clip 52, a pin plate (not shown) in which a plurality of pins (not shown) are arranged upright on the upper surface of the table and hold the film 10 by piercing individual pins into the side portions of the film 10 is provided. You may use it.

The rails are installed on the side of the transport path of the film 10, and the pair of rails are arranged apart from each other. The chain is hung on a prime mover sprocket and a driven sprocket (not shown) and is movably attached along rails. The clips 52 are attached to the chain at predetermined intervals, and the rotation of the driving sprocket causes the clips 52 to circulate and move along the rails. The clip 52 starts holding the guided film 10 near the entrance of the tenta 38, moves toward the exit, and releases the holding near the exit. The clip 52 released from holding moves to the vicinity of the entrance again and holds the newly guided film 10. In this way, the clip 52 is conveyed in the longitudinal direction while gripping each side portion of the film 10.

By changing the track of the rail, the running path of the clip 52 can be changed. As a result, the film 10 being conveyed can be stretched in a direction intersecting the longitudinal direction (for example, the width direction).

The tenta 38 is provided with a blower 53 above the transport path of the film 10. An outlet (not shown) through which the dry gas flows out is formed on the lower surface of the blower 53, and the dry gas (for example, air) is blown out toward the passing film 10. The temperature of the dry gas from the blower 53 is preferably in the range of 40 ° C. or higher and 200 ° C. or lower. A blower having the same structure may be provided below the transport path of the film 10. Since the tenta 38 has the blower 53 in this way, the film 10 can be dried while passing through the tenta 38 (first drying step). However, the tenta 38 may not be provided.

The roller dryer 41 includes a plurality of rollers 41a and an air conditioner (not shown). The plurality of rollers 41a support the film 10 on the peripheral surface. The film 10 is wound around the roller 41a and conveyed. The air conditioner adjusts the temperature, humidity, etc. inside the roller dryer 41. The temperature inside the roller dryer 41 is preferably in the range of 80 ° C. or higher and 160 ° C. or lower. The humidity inside the roller dryer 41 is preferably in the range of 0% or more and 50% or less in relative humidity. The film 10 can be dried while passing through the roller dryer 41 (second drying step).

Since the casting film 51 contains the citric acid ester 12, the formed film 10 also contains the citric acid ester 12. Therefore, as with the casting film 51, the film 10 is also dried by the citric acid ester 12, so that the film 10 is dried more quickly by the tenter 38 and the roller dryer 41, and the production efficiency of the film 10 is improved.

The slitter 42 is for cutting off each side end of the film 10. This excision brings the film 10 to, for example, the desired product width. A slitter having the same configuration as the slitter 42 may be arranged at another position. For example, between the casting unit 37 and the tenta 38 and / or between the tenta 38 and the roller dryer 41. When arranging between the casting unit 37 and the tenta 38, for example, the clip 52 is formed by cutting off the side end portion of the film 10 from the casting unit 37 toward the tenta 38 immediately before being introduced into the tenta 38. Gripping by is more reliable. Further, when arranging between the tenta 38 and the roller dryer, the transportation by the roller 41a is more stable by cutting off the gripping trace by the clip 52. The excised side end may be guided by a crusher (not shown), crushed into chips by the crusher, and used as a raw material for a new dope 21. In order to suppress the above-mentioned fleece transition, it is preferable that the excised side end portion is shielded from light until it is used as a raw material for a new dope 21.

The winder 43 is for winding the film 10 in a roll shape. The winder 43 includes a motor (not shown), and a winding core 54 is set in the winder 43. The film 10 is wound around the winding core 54 by rotating the winding core 54 by a motor.

The wound film 10 is produced from a dope 21 made of a resin composition for a film, and contains the above-mentioned resin, citric acid ester, and monohydric alcohol. Therefore, since the citric acid ester as described above is contained, the films are less likely to stick to each other due to the above-mentioned presumed action, and the stickability is good. Further, since it contains the above-mentioned citric acid ester, the haze of the film itself is also good.

The citric acid ester 12 and various additives other than the citric acid ester 12 are not limited to the method of mixing with the resin 11 or the like in the mixing tank 26 as described above. For example, an addition pipe (not shown) that guides at least a part of these additives may be connected to the pipe 33 and added in the pipe 33. In that case, a well-known static mixer (for example, a thru-zamixer or the like) may be provided in the pipe 33 for mixing.

The film is not limited to a single layer structure, but may have a multi-layer structure. For example, as shown in FIG. 2, some of the films 60 for which the present invention has been carried out are films having a three-layer structure. In the case of a multi-layer structure, the number of layers is not limited to three, and may be two or four or more. The film 60 includes an inner layer located inside the film body 61 in the thickness direction D1, a first outer layer 62 forming one film surface (hereinafter referred to as a first film surface) 60a of the film 60, and the other of the film 60. A second outer layer 63 forming a film surface (hereinafter referred to as a second film surface) 60b is provided. The first outer layer 62 is provided on one surface 61a of the film body 61, and the second outer layer 63 is provided on the other surface 61b of the film body 61. The first film surface 60a is a film surface peeled off from the belt 46 in the manufacturing method described later. When the multi-layer structure is a two-layer structure, the film (not shown) does not have the second outer layer 63, and is composed of the film body 61 and the first outer layer 62. When the multi-layer structure is a layer structure of four or more layers, for example, the film body 61 is formed in the multi-layer structure.

In this example, the thickness T60 of the film 60 is within the range of 5 μm or more and 100 μm or less, but the film 60 is not limited to this range and may be thicker than 100 μm or thinner than 5 μm. The thickness T60 when used as an optical film is preferably in the range of 10 μm or more and 60 μm or less. For example, in a mobile display cover film application, the thickness T60 is 10 μm or more and 50 μm or less, and when used as a diaphragm for earphones or the like, the thickness T60 is 5 μm. It is preferably within the range of 15 μm or more. The thickness of the film having a multi-layer structure other than three layers, that is, a multi-layer structure having two layers or four or more layers is the same as the thickness T60. In FIG. 2, the thickness is the thickness in the thickness direction D1.

The thickness T61 of the film body 61 is larger than the thickness T62 of the first outer layer 62 and the thickness T63 of the second outer layer 63. The thickness T61 is preferably in the range of 3 μm or more and 92 μm or less. The thickness T62 is preferably in the range of 1 μm or more and 4 μm or less, and preferably as small as possible within the range in which the action is exhibited. The thickness T63 is preferably in the range of 1 μm or more and 4 μm or less, and preferably as small as possible within the range in which the action is exhibited.

The film 60 also includes the resin 11 and the citric acid ester 12 in the same manner as the film 10. Specifically, it is as follows. The film body 61 is made of resin 11. In addition to the resin 11, the film body 61 may contain, for example, an ultraviolet absorber and / or a deterioration inhibitor.

The first outer layer 62 contains the resin 11 and the citric acid ester 12. In the first outer layer 62, the mass of the citric acid ester 12 is preferably in the range of 0.1% or more and 10% or less with respect to the mass of the resin 11, and this example is also within this range. The first outer layer 62 may contain, for example, a matting agent, an antioxidant and / or an ultraviolet absorber, in addition to the resin 11 and the citric acid ester 12. Further, a known peeling accelerator that improves the peelability may be contained as an additive.

The second outer layer 63 is made of resin 11. In addition to the resin 11, the second outer layer 63 may contain, for example, a matting agent, a deterioration inhibitor, and / or an ultraviolet absorber, and in this example as well, the matting agent 68 made of silica described above (FIG. 3). See).

When the film 60 is manufactured in a long length, it is preferable that at least one of the first outer layer 62 and the second outer layer 63 contains the matting agent 68. When at least one of them contains the matting agent 68, the mass ratio of the matting agent 68 is in the range of 0.020% or more and 5.0% or less with respect to the mass of the resin 11 in the containing layer. Is preferable. When it is 0.020% or more, the slipperiness between the films 60 is more reliably exhibited as compared with the case where it is less than 0.020%. When it is 5.0% or less, a more transparent film 60 can be obtained as compared with the case where it exceeds 5.0%. The mass ratio of the matting agent 68 is the mass ratio of the matting agent 68 to the resin 11. That is, the mass ratio (unit:%) of the matting agent 68 is obtained by (M68 / M11) × 100 when the mass of the matting agent 68 is M68. When used as an optical film, the mass of the matting agent 68 in the entire film 60 is in the range of 0.10% or more and 2.0% or less with respect to the mass of the resin in the entire film 60. preferable.

The matting agent 68 makes a film having the above-mentioned silica within a range of 0.2 μm or more and 20 μm or less from the surface on at least one side of the film. The reason why the matting agent 68 is present at a position within the above range from the surface is that the citric acid ester diffuses the matting agent from the outer layer to which it is added to the entire film layer due to the effect of imparting the ability to accelerate the drying of the film. This is suppressed, solvent drying from the surface is promoted at the initial stage of drying on the surface having the matting agent, and a surface layer having a high resin concentration is formed, and then the matting agent is settled in the layer in the drying process. This is because it is possible to prevent the convex portion from becoming low. Since the matting agent 68 is present at a position within the above range, there is an advantage that the slipperiness of the film can be ensured.

In this example, the citric acid ester 12 is contained in all of the first outer layer 62, the second outer layer 63 and the film body 61, but the citric acid ester 12 is contained in the first outer layer 62, the film body 61 and the second outer layer 63. Of these, at least one may be contained, or any two may be contained. When the citrate ester 12 is contained in the first outer layer 62 and the film body 61 and / or the second outer layer 63, the sum of the masses of the citrate ester 12 in the film body 61 and the second outer layer 63 is the film. It is preferably in the range of 0.1% or more and 10% or less with respect to the sum of the masses of the resin 11 in the main body 61 and the second outer layer 63.

The film manufacturing equipment 70 shown in FIG. 3 is an example of equipment for manufacturing the film 60, and includes a dope preparation device 72 and a film manufacturing device 73. In FIG. 3, the same devices and members as those in FIG. 2 are designated by the same reference numerals as those in FIG. 2, and the description thereof will be omitted.

The dope preparation device 72 is for preparing a dope (hereinafter referred to as a casting dope) 75 (see FIG. 4) to be subjected to casting. In the dope preparation device 72, the pipe 33 is branched into three pipes (hereinafter referred to as branch pipes) 33a, 33b and 33c downstream of the pump 32, and each of the

branch pipes

33a, 33b and 33c is a film manufacturing device. It is configured in the same manner as the dope preparation device 22 except that it is connected to the casting die 76 of 73.

The mixing tank 26 is guided with the resin 11 constituting the film body 61, the first outer layer 62, and the second outer layer 63, and the solvent 15. The resin 11 and the solvent 15 are mixed by the mixing tank 26, and the resin 11 is dissolved in the solvent 15. As a result, a dope (hereinafter, referred to as a base dope) 78 as a base of the casting dope 75 is produced. In the base dope 78, the concentration of the resin 11 is preferably in the range of 15% or more and 30% or less. The resin concentration of the base dope 78 is the mass ratio of the resin to the mass sum of the resin 11 and the solvent 15, similar to the concentration of the resin of the dope 21. That is, it is calculated by {M11 / (M11 + M15)} × 100.

The base dope 78 reaches the branch position PS where the pipe 33 branches into the

branch pipes

33a, 33b and 33c via the filter 28 and the storage tank 31 as in the case of the dope 21. The base dope 78 has a flow divided at the branch position PS and is guided to each of the

branch pipes

33a, 33b and 33c to form the first outer layer 62 (see FIG. 2) and the first liquid 81 (see FIG. 4). It is used for each of the second liquid 82 (see FIG. 4) forming the film body 61 (see FIG. 2) and the third liquid 83 (see FIG. 4) forming the second outer layer 63 (see FIG. 2).

An addition pipe 80a for adding the first additive is connected to the branch pipe 33a, and the first additive in this example is citric acid ester 12. The first liquid 81 (see FIG. 4) is produced by supplying the citric acid ester 12 to the base dope 78 flowing in the branch pipe 33a by the addition pipe 80a. The citric acid ester 12 is preferably supplied to the branch pipe 33a as a solution in a state of being dissolved in the solvent 15. The supply flow rate of the citric acid ester 12 is set according to the flow rate of the base dope 78 flowing through the branch pipe 33a and the concentration of the resin 11 in the base dope 78. As a result, the first liquid 81 having the same mass ratio of the citric acid ester 12 as the first outer layer 62 is prepared. When the first outer layer 62 contains an additive other than the citric acid ester 12, the first liquid 81 containing the additive may be prepared. Therefore, the base is prepared by the same method as the addition of the citric acid ester 12. The additive may be added to the agent dope 78.

An addition pipe 81a for adding the solvent 15 is connected to the branch pipe 33a, and the addition pipe 81a is provided with a valve (not shown) for adjusting the opening degree. The solvent 15 is a mixture of methylene chloride and methanol in advance (solvent adjustment step). The solvent adjusting step is the same as described above. The addition of the solvent 15 is performed when the concentration of the resin 11 in the first liquid 81 is lowered. Therefore, when it is not necessary to adjust the concentration of the resin 11 in the first liquid 81, the valve is closed (opening is zero) and the solvent 15 is not added. The flow rate of adding the solvent 15 is adjusted by adjusting the opening degree of the valve, and is set according to the flow rate of the first liquid 81 flowing through the branch pipe 33a and the concentration of the resin 11. As a result, the first liquid 81 having the same concentration of the resin 11 as the first outer layer 62 is produced. In this example, the addition pipe 81a is connected downstream from the connection position of the addition pipe 80a in the branch pipe 33a. However, the connection position of the addition pipe 81a is not limited to this example. For example, the addition pipe 81a may be connected to the addition pipe 80a.

The base dope 78 flowing through the branch pipe 33b is guided to the casting die 76 and is used for casting as the second liquid 82 (see FIG. 4). That is, the base dope 78 flowing from the branch pipe 33b to the casting die 76 is used as the casting dope 75.

An additive pipe 80b for adding the second additive is connected to the branch pipe 33c, and the second additive in this example is the matting agent 68. The matting agent 68 is supplied to the base dope 78 flowing in the branch pipe 33c by the addition pipe 80b, so that the third liquid 83 (see FIG. 4) is produced. The matting agent 68 is preferably supplied to the branch pipe 33c as a dispersion liquid dispersed in the solvent 15. The supply flow rate of the matting agent 68 is set according to the flow rate of the base dope 78 flowing through the branch pipe 33c and the concentration of the resin 11 in the base dope 78. As a result, the third liquid 83 having the same mass ratio of the matting agent 68 as the second outer layer 63 is produced. When the second outer layer 63 contains an additive other than the matting agent 68, a third liquid 83 containing the additive may be prepared. Therefore, the base doping is performed by the same method as the addition of the matting agent 68. The additive may be added to 78.

An addition pipe 81b for adding the solvent 15 is connected to the branch pipe 33b, and the addition pipe 81b is provided with a valve (not shown) for adjusting the opening degree. The addition of the solvent 15 is performed when the concentration of the resin 11 in the third liquid 83 is lowered. Therefore, when it is not necessary to adjust the concentration of the resin 11 in the first liquid 81, the valve is closed (opening is zero) and the solvent 15 is not added. The flow rate of adding the solvent 15 is adjusted by adjusting the opening degree of the valve, and is set according to the flow rate of the third liquid 83 flowing through the branch pipe 33b and the concentration of the resin 11. As a result, the third liquid 83 having the same concentration of the resin 11 as the second outer layer 63 is produced. In this example, the addition pipe 81b is connected downstream from the connection position of the addition pipe 80b in the branch pipe 33b. However, the connection position of the additive pipe 81b is not limited to this example. For example, the addition pipe 81b may be connected to the addition pipe 80b.

The film manufacturing apparatus 73 has the same configuration as the film manufacturing apparatus 23, except that the casting unit 85 is provided instead of the casting unit 37. The casting unit 85 is configured in the same manner as the casting unit 37, except that it includes a well-known casting die 76 for co-casting instead of the casting die 36. The casting die 76 includes a first flow path, a second flow path, and a third flow path (not shown) through which the first liquid 81, the second liquid 82, and the third liquid 83 flow independently, and the first of these. It includes a confluence portion (not shown) at which the flow paths to the third flow path merge, and a fourth flow path (not shown) formed from the confluence portion following the discharge port 76a. In the casting die 76, a first flow path, a second flow path, and a third flow path are formed in order from the upstream side in the traveling direction of the belt 46. The branch pipe 33a is connected to the first flow path, the branch pipe 33b is connected to the second flow path, and the branch pipe 33c is connected to the third flow path. As a result, the casting unit 85 forms a casting film 86 having a three-layer structure (casting step). Details of the casting film 86 formed by the first liquid 81 to the third liquid 83 will be described later with reference to another drawing.

The casting film 86 is peeled off from the belt 46 in the same manner as the casting film 51 to form the film 60 (peeling step). The formed film 60 is dried by a tenta 38 and a roller dryer 41 (drying step), each side end is cut off by a slitter 42, and then rolled around a winding core 54 by a winder 43. Taken.

In the casting step, as shown in FIG. 4, the first liquid 81, the second liquid 82, and the third liquid 83 are used as the casting dope 75. On the belt 46, the first liquid 81 to the third liquid 83 are cast in a state where the second liquid 82 overlaps the first liquid 81 and the third liquid 83 overlaps the second liquid 82. As a result, the casting film 86 including the first layer 86a formed by the first liquid 81, the second layer 86b formed by the second liquid 82, and the third layer 86c formed by the third liquid 83. Is formed. The thickness of each of the first layer 86a, the second layer 86b, and the third layer 86c to be formed is the concentration of the resin 11 in each of the first liquid 81 to the third liquid 83, and the target first outer layer 62 and the film. It is set according to the thickness of the main body 61 and the second outer layer 63. In FIG. 4, the traveling direction of the belt is the traveling direction D2 of the belt.

The concentration of the resin 11 in each of the first liquid 81 and the third liquid 83 is preferably lower than the concentration of the resin 11 in the second liquid 82. As a result, the first liquid 81 and the third liquid 83 become higher than the second liquid 82, so that the flow of the second liquid 82 is sealed by the flow of the first liquid 81 and the third liquid 83 (encapsulation effect). ). This encapsulation effect contributes to the improvement of the smoothness of the film surface of the casting film 86 and the film surface of the film 60. The concentration of the resin 11 in the second liquid 82 is preferably 15% or more and 30% or less. The concentration of the resin 11 in each of the first liquid 81 and the third liquid 83 is preferably lower than the concentration of the resin 11 in the second liquid 82 and in the range of 12% or more and 28% or less. The concentration of the resin 11 in each of the first liquid 81 and the third liquid 83 is more preferably in the range of 13% or more and 25% or less, and further preferably in the range of 15% or more and 22% or less. ..

Also in this example, since the first layer 86a contains the citric acid ester 12, the peeling load of the casting film 86 from the belt 46 can be suppressed to a small value, and a smooth film 60 can be obtained. Further, the inclusion of the citric acid ester 12 promotes the drying of the casting film 86 and the film 60.

The film 10 or the film 60 was manufactured by the

film manufacturing facility

20 or 70, and used as Examples 1 to 19. As the polyarylate, U Polymer (registered trademark) U-100 manufactured by Unitika Ltd. was used. As the polyimide, the polyimide described below was used. In Examples 1 to 11, a film 10 having a single-layer structure was produced by using polyarylate as the resin 11 using the film manufacturing equipment 20. In Examples 12 and 14, a film 60 having a two-layer structure was produced using polyarylate as the resin 11 using the film production equipment 70. In Example 13, using the film manufacturing equipment 70, polyarylate was used as the resin 11, and a film 60 having a three-layer structure was manufactured. In Examples 15 to 18, a film 10 having a single-layer structure was produced by using polyimide as the resin 11 using the film manufacturing equipment 10. In Example 19, a film manufacturing facility 70 was used to manufacture a film 60 having a two-layer structure using polyimide as the resin 11. The types of resin used are shown in the "Type" column of Table 1 "Resin".

The two-layer structure film 60 was composed of a first outer layer 62 and a main body 61 (see FIG. 2). Further, the film 60 having a three-layer structure is composed of a first outer layer 62, a main body 61, and a second outer layer 63 (see FIG. 2). The composition and thickness of each layer in each embodiment are described in the "thickness" column of "layer structure" in Table 1 in the order of the first outer layer 62, the main body 61, and the second outer layer 63 of the film 60 (see FIG. 2). It is shown in the 1 / main body / second column. In the case of a single-layer structure film, it is described as "-".

Further, the film 60 having a two-layer structure or a three-layer structure was produced by adding the citric acid ester to the mixing tank 26 in the film production facility 70. Therefore, in the film manufacturing facility 70, the dope 21 was used instead of the base dope 78. Further, the main body 61 is manufactured from the dope 21 using the branch pipes 33a to 33c, and the first outer layer 62 and / or the second outer layer 63 is made from the third liquid 83 separately adjusted as described below. Manufactured.

The polyimide used was manufactured as follows. Under a nitrogen atmosphere, 1 g of isoquinoline was charged into a reaction vessel to which a vacuum pump equipped with a solvent trap and a filter was connected. Next, 375 g of γ-butyrolactone and 104 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB, 2,2'-Bis (trifluoromethyl) benzidine) were added to the reaction vessel. It was stirred and dissolved. Further, after adding 145 g of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, 4,4'-(Hexafluoroisopropylide) diphthalic anhydride) to the reaction vessel, the mixture is stirred and raised in an oil bath. We started warming. The mixture was heated and stirred at 80 ° C. for 6 hours. Then, the outside temperature was heated to 190 ° C., and the water generated by imidization was azeotropically distilled off together with toluene. After continuing heating, refluxing and stirring for 6 hours, no water was observed. Subsequently, the mixture was heated for 7 hours while distilling off toluene, and after distilling off toluene, methanol was added to reprecipitate. When GPC measurement was performed on the polyimide in the obtained polyimide varnish, the weight average molecular weight was 360,000. The fluorine atom content of the polyimide was 31.3% by mass. Tg was 335 ° C.

The types of compounds used as the citric acid ester 12 are shown in the "Type" column of "Additives" in Table 1. Those without additives are described as "None" in the above column of Table 1. As the citric acid ester, a compound (mixture) prepared by adjusting the amount of carboxyl residues as shown in Table 1 by a partial hydrolysis reaction in which water was added to the following compounds was used. As the isopropyl citrate, the one described in the formula (2) was used. As butyl citrate, tributyl citrate manufactured by Tokyo Chemical Industry Co., Ltd. was used. Pentyl citrate was synthesized by the esterification reaction of citric acid and sec-pentyl alcohol. For methylene chloride, methylene chloride manufactured by Tokuyama Corporation was used, and for methanol, methanol manufactured by Mitsubishi Gas Chemical Company, Inc. was used.

The dope 21 containing polyarylate to be used in the

film manufacturing facility

20 or 70 was prepared as follows. First, the polyarylate was placed in a heating device, heated at 140 ° C. for 2 hours, and resin-dried for dehydration. As a result, the water content before heating was 0.18% based on the entire polyarylate, but it became 0.04%. Next, in the mixing tank 26, 128.3 kg of methylene chloride and 2.6 kg of methanol were mixed to prepare a solvent 15. The methanol ratio (mass ratio) in the solvent was 2%, and the volume was 100 L. The ratio of methanol to the whole solvent is shown in the "Methanol ratio" column of "Solvent". The solvent 15 was stirred and 150 g of citric acid ester was added. Then, 29.9 kg of polyarylate was added over 25 minutes. This was stirred to dissolve the polyarylate. This was used as a dope 21 and provided to a

film manufacturing facility

20 or 70. The mass ratio of each component excluding the solvent of the dope 21 containing polyarylate was as follows. The mass ratio of the citric acid ester when the polyarylate is 100 parts by mass is shown in the "Addition amount" column of "Additives" in Table 1. The mass ratio of polyarylate in the dope 21 was 18.6%.

Dope 21 containing polyarylate
Polyarylate 100.0 parts by mass Isopropyl citrate 0.50 parts by mass

The types of compounds used as matting agents are shown in the "Types" column of "Matting agents" in Table 1. As the matting agent, silica which had been hydrophobized by TMS was used. "R972" was AEROSIL® R972 manufactured by Nippon Aerosil Co., Ltd., and had a surface coverage of 0.008 and a specific surface area of 130 m ² / g. "NX90S" is AEROSIL (registered trademark) NX90S manufactured by Nippon Aerosil Co., Ltd., which has a surface coverage of 0.016 and a specific surface area of 90 m ² / g.

The third liquid, which is a dope containing the matting agent 68, was prepared as follows. A matting agent was added to the dope 21 containing polyarylate, and the 100 L portion was stirred for 60 minutes. Then, 100 L was dispersed at 180 rpm for 60 minutes with a titania ball having a diameter of 3 mm with an attritor (Atwriter 15S manufactured by Nippon Coke Industries, Ltd.). The mass ratio of each component of the third liquid was as follows. In this example, the amount of the matting agent is 1.3 parts by mass with respect to the polyarylate. The amount of the matting agent for the resin used in each example is shown in the "Amount" column of "Matting agent" in Table 1.

Third liquid containing polyarylate Dope 21 containing polyarylate 21 100.0 parts by mass Matting agent 0.240 parts by mass

The polyimide-containing dope 21 to be used in the

film manufacturing facility

20 or 70 was prepared in the same manner as the polyarylate-containing dope 21. First, the polyimide was placed in a heating device and heated at 140 ° C. for 2 hours to carry out resin drying for dehydration. As a result, the moisture content before heating was 0.30% based on the entire polyimide, but it became 0.04%. Next, in the mixing tank 26, 126.5 kg of methylene chloride and 3.9 kg of methanol were mixed to prepare a solvent 15. The ratio of methanol in the solvent was 3%, and the volume was 100 L. The solvent 15 was stirred and 164 g of citric acid ester was added. Then, 32.7 kg of polyimide was added over 25 minutes. The polyimide resin concentration in Dope 21 was 20.0%. Further, the third liquid containing the matting agent was also prepared in the same manner as the third liquid containing polyarylate. That is, it was prepared in the same manner as above except that the polyarylate was changed to polyimide. The mass ratio of each component of the dope 21 containing polyimide and the third liquid was as follows. Regarding polyimide, Table 1 shows "resin", "additive", "matting agent", "solvent", and "layer structure" in the same manner as in the case of polyarylate.

Dope 21 containing polyimide
Polyimide 100.0 parts by mass Isopropyl citrate 0.5 parts by mass

Third liquid containing polyimide Dope 21 containing polyimide 21 100.0 parts by mass Matting agent 0.260 parts by mass

Details in the casting process, peeling process and drying process were as follows. As the casting die and the metal lip (die lip), those made of SUS316L or the like were used. The dope 21 or the third solution was passed through the filter 28, respectively. First, it was passed through a 30 μm filter, and then through a 10 μm filter. Dope 21 or the third solution was delivered from the casting die at 1450 cc / min. The belt 46 was operated at 5 m / min. Therefore, the flow rate was 5 m / min. The belt 46 was a metal band made of SUS. Drying was recommended on the metal band by the film manufacturing facility 20. After peeling in the peeling step, drying proceeded in the drying step. It was first dried at 50 ° C. and then at 140 ° C. for 10-15 minutes. The film was wound around a core made of FRP (Fiber-Reinforced Plastics) with a film width of 800 mm and a film length of 500 m.

[Example 1] to [Example 11]
In Examples 1 to 11, a film 10 having a single-layer structure was produced by using polyarylate as the resin 11 using the film manufacturing equipment 10. As the casting dope 75, a dope 21 containing a polyarylate without a matting agent and a third liquid containing a matting agent in the dope 21 were used.

[Example 12] to [Example 14]
In Examples 12 to 14, a film 60 having a two-layer or three-layer structure was produced using polyarylate as the resin 11 using the film production equipment 70. Examples 12 and 14 had a two-layer structure, and Example 13 had a three-layer structure film 60. As the casting dope 75, a dope 21 containing a polyarylate without a matting agent and a third liquid containing a matting agent in the dope 21 were used.

[Example 15] to [Example 18]
In Examples 15 to 18, a film 10 having a single-layer structure was produced by using polyimide as the resin 11 using the film manufacturing equipment 10. As the casting dope 75, a third liquid containing polyimide and a matting agent was used.

[Example 19]
In Example 19, a film manufacturing facility 70 was used to manufacture a film 60 having a three-layer structure using polyimide as the resin 11. As the casting dope 75, a dope 21 containing polyimide without a matting agent and a third liquid containing a matting agent in the dope 21 were used.

Table 1 shows the physical properties of the manufactured film. In Table 1, the total thickness of the produced film is described in the "thickness" column of "film formation", and the first outer layer 62 / main body 61 / second outer layer 63 (thickness) of the "layer structure". The thickness of each is described in the order of (see FIG. 2). The side where the first outer layer 62 is in contact with the support.

Adhesion of dope 21 or third liquid to metal lip, peeling load of cast film, acceleration of drying, degree of cloudiness of film 10 or film 60, amount of methylene chloride remaining on film, films The stickiness and take-up property of the film were evaluated by the following methods and criteria. The results of each evaluation are shown in Table 1.

1. 1. Resin Adhesiveness of Lip Dope 21 or the third liquid was discharged from the tip of the metal lip of the casting die. The discharged liquid was received in the receiving container. The discharge was continuously performed for 10 minutes, and the deposits on the boundary (discharge liquid end) between the dope discharge portion and the non-dope discharge portion of the metal lip were visually observed and evaluated according to the following criteria. A and B pass, C fails.
A; No deposits are observed B; Deposits are formed but can be removed during ejection.
C: There are deposits that cannot be removed during discharge.

2. 2. Peeling load A sample for evaluation was taken from the dope 21 stored in the storage tank 31. The mass of the resin 11 made of polyarylate or polyimide in the sample was 20% with respect to the sum of the masses of the solvent 15 and the resin 11. A casting film was formed by casting a sample on a support whose temperature was adjusted to 20 ° C. The support used was made of SUS. The thickness of the casting film was set so that the thickness of the film sample obtained by drying was the same as the thickness of the film 10 produced in each example. The cast film formed was allowed to stand at room temperature for 2 minutes. By this standing, the cast film was dry compared to immediately after casting, but it was not completely dried. Immediately after this standing, 13 cutting lines were inserted into the casting film with a width of 2 cm using a cutter. In one of the 12 cutting pieces having a width of 2 cm formed by the cutting line (the first cutting piece), one end of the cutting piece in the longitudinal direction was gripped with a clip. The clip pulled up the one end of the cut piece at a speed of 2 cm / sec so that the angle between the surface of the support and the cut piece was 45 °. The load required for this pulling was measured with a load cell (MinebeaMitsumi Co., Ltd. microload small tensile compression type UTA-200GR) and used as the peeling load of the first cut piece (first peeling load). After that, the peeling load was obtained for the remaining 11 cut pieces in the same manner, and the peeling load was set to the second peeling load to the twelfth peeling load. The time intervals for obtaining the first peeling load to the twelfth peeling load should be as equal as possible, and the final measurement of the twelfth peeling load should be approximately 30 minutes after the formation of the casting film. I made it. The largest value among the first to twelfth peeling loads, which are the results of these twelve measurements, was taken as the peeling load of the casting film.

3. 3. Acceleration of drying Similar to the method in the evaluation of the peeling load described above, a sample of dope 21 was taken to form a casting film. The mass of the resin 11 in the sample was 20% with respect to the sum of the masses of the solvent 15 and the resin 11. In addition, the thickness of the casting film was also set in the same manner as in the method for evaluating the peeling load described above. The formed cast film was allowed to stand at room temperature, and the solvent content after 5 minutes was calculated by the above-mentioned calculation formula, and evaluated as a drying accelerator according to the following criteria. A and B pass, and C fails.
A: The solvent content was in the range of 0% or more and 40% or less.
B; The solvent content was in the range of 41% or more and 80% or less.
C; The solvent content was in the range of 81% or more and 150% or less.

4. Haze The haze of the obtained film 10 was evaluated as the degree of cloudiness. The haze was obtained with a haze meter NDH 7000 manufactured by Nippon Denshoku Kogyo Co., Ltd. based on the Japanese Industrial Standard JIS K 7136. Haze 10% or less is a pass, and haze 10% or more is a failure. A haze of 5% or less is a good degree of cloudiness of the film.

5. Amount of methylene chloride remaining on the film As a measurement sample, a film piece was dissolved in chloroform so as to be about 0.9%, and the amount of methylene chloride in the measurement sample was measured by a calibration curve method by gas chromatography measurement. As an apparatus, gas chromatography (manufactured by Shimadzu Corporation) GC-2014 was used, and as a separation column, INTER CAP1 (length 30 m, inner diameter 0.32 mm) manufactured by GL Science was used. The measurement conditions are as follows: the measurement sample is injected at an injection volume of 0.1 μL, the column temperature is 60 ° C, the oven temperature program starts measurement from 60 ° C, and the temperature rises to 120 ° C in 5 minutes and to 160 ° C in the next 5 minutes. It was a step to do. The amount of methylene chloride in the measurement sample / the concentration of the film piece in the measurement sample was determined as a percentage, and the measurement results were shown in the "Methylene chloride remaining amount" column of Table 1 as the remaining amount of methylene chloride remaining in the film. ..

6. Sticking property The degree to which sticking was reduced with respect to the obtained film 10 or film 60 was evaluated as follows. First, three pieces of each film cut into a 7 cm × 7 cm square were stacked. Next, the humidity was adjusted for 24 hours under the conditions of a temperature of 25 ° C. and a humidity of 50% with three layers of each film, and then placed in an environment of a temperature of 40 ° C. and a humidity of 20% with the three films stacked. Then, after placing a 15 kg weight on each of the three stacked films and leaving them for 24 hours, the ratio S (unit:%) of the sticking area of the film 10 to the contact area of the films was determined. The obtained ratio S of the sticking area was evaluated in the following four stages A to D. If the evaluation result is within A, B or C, the film is within the practically acceptable range, and the film is accepted. The evaluation result of D was rejected.
A: Less than 20% B: 20% or more and less than 35% C: 35% or more and less than 45% D: 45% or more

7. Windability The obtained

film

10 or 60 was wound into a roll using a winding device to evaluate the winding property. Here, the evaluation of the windability is an evaluation of the degree to which failures such as beco (deformation of the film) and wrinkles do not occur. The rewindability was evaluated in the following four stages A to D according to the degree of occurrence of beco or wrinkle failure in the film roll at the time of winding. D is a failure.
A: No beco or wrinkles occurred.
B: Beco and wrinkles occurred.
C: Beko and wrinkles were strongly generated.
D: Beco and wrinkles were strongly generated on the entire film, and the entire length could not be wound.

[Comparative Example 1] to [Comparative Example 7]
Using the resin compositions shown in Table 1, films having a single-layer structure were prepared and used as Comparative Examples 1 to 7. As for the additive, as the triethyl citrate of Comparative Example 5, CITROFOL (registered trademark) AI (triethyl citrate) manufactured by Jungbunzrawer Japan Co., Ltd. was used. In Comparative Example 6, as citrate monoglyceride having 16 carbon atoms, as Poem (registered trademark) K-37V produced by RIKEN Vitamin Co., Ltd., and in Comparative Example 7, as acetyl citrate (2-ethylhexyl) having 8 carbon atoms, CITROFOL (registered trademark) AHII manufactured by Jungbunzrawer Japan Co., Ltd. was used. When no additives or the like were used (Comparative Examples 1 to 4), "-" was described in each column of Table 1. Other conditions, including the polyarylate used, were the same as in Examples 1 to 11.

[Comparative Example 8] to [Comparative Example 9]
Using the resin compositions shown in Table 1, a film having a single-layer structure was prepared and used as Comparative Examples 8 to 9. Since no additive was used, "None" was entered in the "Type" column of "Additive" in Table 1, and "-" was entered in the "carboxyl residue amount" and "Addition amount" columns. Other conditions, including the polyimide used, were the same as in Examples 15 to 18.

In the comparative example as well, as in the examples, the adhesion of the dope 21 to the metal lip, the peeling load of the casting film, the acceleration of drying, the degree of white turbidity of the film 10 or the film 60, and the methylene remaining on the film. The amount of chloride, the stickiness between films, and the rewindability were evaluated by the following methods and criteria. The results of each evaluation are shown in Table 1.

10,60 Film 11 Resin 12 Citrate ester 15

Solvent

20,70 Film production equipment 21

Dope

22,72

Dope preparation equipment

23,73 Film production equipment 26

Mixing tank

27,32 Pump 28 Filter 31 Storage tank 33 Piping 33a-

33c Branch Piping

36,76 Casting die 36a,

76a Discharge port

37,85 Casting unit 38 Tenter 41 Roller dryer 41a Roller 42 Slitter 43 Winder 46 Belt 47 Roller 48 Stripping

roller

51,86 Casting film 52 Clip 53 Blower 54 Winding core 60a First film surface 60b Second film surface 61 Film body 61a One surface of film body 61b The other surface of film body 62 First outer layer 63 Second outer layer 68 Matting agent 75 Casting dope 78

Base dope

80a , 80b, 81a, 81b Additive piping 81 1st liquid 82 2nd liquid 83 3rd liquid 86a 1st layer 86b 2nd layer 86c 3rd layer D1 Thickness direction D2 Belt running direction PC spreading position PP stripping position PS branch position

Claims

A resin having an aromatic ring and / or an imide ring in the main chain, having a glass transition point of 170 ° C. or higher, and dissolving 10% or more in mass percent concentration with methylene chloride.
A citric acid ester having a carboxyl residue and an alcohol residue having a carbon number of 3 or more and 5 or less.
With methylene chloride,
Monohydric alcohols with carbon atoms in the range of 1 or more and 3 or less,
A resin composition for a film having.
The film resin composition according to claim 1, wherein the resin is polyarylate or polyimide.
The resin composition for a film according to claim 1 or 2, wherein the citric acid ester has a carboxyl residue amount in the range of 0.2 or more and 2.9 or less.
The resin composition for a film according to any one of claims 1 to 3, wherein the citric acid ester contains at least one selected from the group consisting of isopropyl citrate, butyl citrate, and pentyl citrate.
The film resin composition according to any one of claims 1 to 4, wherein the citric acid ester is contained in the range of 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the resin.
The resin composition for a film according to any one of claims 1 to 5, wherein the monohydric alcohol is contained in a mass percent concentration of 10% or less with respect to the methylene chloride.
The resin composition for a film according to any one of claims 1 to 6, which contains silica modified with a trimethylsilyl group and has a surface coverage of 0.005 or more and 0.120 or less.
A casting step of forming a casting film by casting a dope made of the resin composition for a film according to any one of claims 1 to 7 on a metal support.
A peeling step of forming a film by peeling the cast film from the support,
A drying step of drying the film and
A method for producing a film having.
In the casting step, the dope is continuously cast on the traveling support.
The film manufacturing method according to claim 8, wherein the peeling step continuously peels the cast film from the support.
The method for producing a film according to claim 8 or 9, which comprises a solvent adjusting step of adding the monohydric alcohol to the methylene chloride.
In the casting step, the first liquid containing the resin and the citric acid ester and the second liquid containing the resin and silica are used as the dope, and the first liquid is in contact with the support. The film according to any one of claims 8 to 10, which forms a cast film having a formed first layer and a second layer formed of the second liquid so as to overlap the first layer. Manufacturing method.
The method for producing a film according to claim 11, wherein the silica has a surface coverage in the range of 0.005 or more and 0.120 or less and is modified with a trimethylsilyl group.
A resin having an aromatic ring and / or an imide ring in the main chain, having a glass transition point of 170 ° C. or higher, and dissolving 10% or more in mass percent concentration with respect to methylene chloride.
A citric acid ester having a carboxyl residue and an alcohol residue having a carbon number of 3 or more and 5 or less.
Monohydric alcohols with carbon atoms in the range of 1 or more and 3 or less,
Film with.
The film according to claim 13, wherein the resin is polyarylate or polyimide.
13. 14. The film according to 14.
The film according to any one of claims 13 to 15, wherein the thickness after drying is in the range of 10 μm or more and 60 μm or less.