WO2024071014A1

WO2024071014A1 - Resin composition for film, film production method, and film

Info

Publication number: WO2024071014A1
Application number: PCT/JP2023/034658
Authority: WO
Inventors: 祥吾片野; 愛継枝; 祐介藤原
Original assignee: 富士フイルム株式会社
Priority date: 2022-09-30
Filing date: 2023-09-25
Publication date: 2024-04-04

Abstract

Provided are a resin composition for a film whereby it is possible to improve the peelability from a support body and produce a film, a film production method, and a film.　The resin composition for a film contains: a polymer resin containing a plurality of each of main structural units not including an acid component and acid structural units including an acid component; an organic compound including a phosphoric acid group and having acid dissociation properties; and a solvent. The film production method includes a flow casting step in which a flow-cast film is formed by flow casting a dope comprising the resin composition for a film onto a metal support body, a peeling steep in which a film is formed by peeling the flow-cast film from the support body, and a drying step in which the film is dried.

Description

Resin composition for film, film manufacturing method, and film

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

A known method for producing transparent films for optical applications that require high smoothness and optical uniformity, or for display applications, is the solution deposition method, in which a polymer resin is made into a solution and cast onto a band of smooth metal support, and then dried and peeled off to produce a film. In the solution deposition method, the peel load when peeling the film from the metal support can sometimes be high. For such cases, it is known to use additives that have a peel-promoting effect (Patent Document 1 or Patent Document 2).

International Publication No. 2020/195377 Japanese Patent Application Laid-Open No. 61-243837

Even if there are additives that promote peeling, they are not a panacea. For example, when making films from various acrylic resins, changes in the material type or polymer lot can make peeling from the metal support difficult.

The present invention aims to provide a resin composition for a film, a film manufacturing method, and a film that can be produced with improved peelability from a support.

The resin composition for films of the present invention comprises a polymer resin containing multiple main structural units that do not contain an acid component and multiple acid structural units that contain an acid component, an organic compound that contains a phosphoric acid group and has acid dissociability, and a solvent.

The organic compound is preferably contained in the range of 0.01 to 10 parts by mass per 100 parts by mass of the polymer resin.

The polymer resin preferably contains a cellulose derivative and a hemicellulose derivative.

The polymer resin is preferably a cellulose ester made from pulp.

The polymer resin is preferably a polyimide or acrylic resin.

The acid unit preferably contains a carboxyl group.

The acid constituent units are preferably contained within a composition ratio of 0.4% to 5% based on the entire polymer resin.

The organic compound is preferably at least one of the compounds represented by the following general formula (1) or (2):

(In the above formula (1) or (2), _R1 is an alkyl group having 1 to 20 carbon atoms, _R2 is an alkyl group having 1 to 20 carbon atoms, _R3 is an alkyl group having 1 to 6 carbon atoms, n is a natural number of 1 to 8, X is a hydroxy group, and Y and Z are each one of a hydroxy group, an alkoxy group, and oxygen.)

The organic compound preferably has an acid value of 100 mg (KOH)/g or more, as measured based on the acid value measurement method according to JIS K0070-1992.

The solvent is preferably a halogenated hydrocarbon solvent.

The method for producing a film of the present invention includes a casting process in which a dope made of a resin composition for a film is cast onto a metal support to form a cast film, a peeling process in which the cast film is peeled off from the support to form a film, and a drying process in which the film is dried.

In the casting process, it is preferable to continuously cast the dope onto the moving support, and in the peeling process, the cast film is continuously peeled off from the support.

The support is preferably a stainless steel band.

The film of the present invention contains a polymer resin that contains multiple main structural units that do not contain an acid component and multiple acid structural units that contain an acid component, and an organic compound that contains a phosphate group and has acid dissociability.

It is preferable that the haze value measured based on JIS K7136 is 2.0 or less.

The present invention provides a resin composition for a film, a film manufacturing method, and a film that can produce a film with improved peelability from a support.

FIG. 1 is a schematic diagram of a film production facility.

The following describes the embodiments. First, the process by which one of the following embodiments was achieved will be described. In solution film formation, it is known to use an additive that promotes peeling in order to prevent the peel load from the metal support from becoming too high when peeling the film from the metal support. However, when forming films from various acrylic films or solvent-soluble polyimides, peeling can be difficult due to changes in the material type or polymer lot. Also, cellulose acylate resin, which is made from pulp as a raw material, has poor peelability, and the surface condition of the peeled film can deteriorate.

In acrylic resins, there may be variations in the acid content in the polymer and its lot, and acid components may be generated over the course of the material's life. In addition, in organic solvent-soluble polyimides, if the reaction during the imidization reaction of the polyimide is insufficient, carboxyl groups may remain in part of the polymer's main chain structure. In addition, in the pulp base material of cellulose acylate, hemicellulose components containing carboxyl groups are included as part of the repeating units of the polymer. When such polymer resins are made into a solution and then formed into a film on a metal support and dried, if there are acid component portions that are acid structural units containing multiple acids in the main chain, the polymer chains in the resin become entangled during drying and interact with the metal support at the multiple acid component portions, which has been found to result in particularly poor peelability on the metal support.

In order to address the deterioration of peelability during solution film formation in such polymer resins, additives that promote peelability were investigated, and it was found that adding an organic compound containing an acid-dissociable phosphate group was effective in sufficiently improving peelability. Since the phosphate group in such compounds has strong acid dissociability, it is believed that it dissociates as an acid more reliably than acid-dissociable groups such as carboxyl groups in the polymer, and has a greater adsorption effect on the metal support surface.

In addition, it is known that solutions using organic solvents, especially chlorine-based organic solvents, are prone to becoming strongly acidic due to the dissociation of hydrochloric acid and the like in the solution, due to the contribution of trace amounts of water and alcohol, but it is presumed that even in such a dope, organic compounds containing acid-dissociable phosphate groups will dissociate sufficiently with acid. Due to the effect of such phosphate-based additives, the addition of a small amount of the dissociated acid preferentially adsorbs onto the metal support surface, and it is believed that even in polymer resins with multiple carboxyl groups in the main chain, the peel load is sufficiently reduced, and the effect of suppressing deterioration of the surface condition during peeling is high. As shown in the examples described below, when phosphate compounds were used, the results were insufficient in terms of peelability and transparency.

Below, we will explain the embodiments of a resin composition for a film that can produce a film with improved peelability from a support, a film production method, and a film.

The resin composition for films of the present invention contains a polymer resin that contains multiple main structural units that do not contain an acid component and multiple acid structural units that contain an acid component, an organic compound that contains a phosphoric acid group and has acid dissociability, and a solvent.

The polymer resin contains multiple main structural units that do not contain acid components and multiple acid structural units that contain acid components. The main structural units that do not contain acid components and the acid structural units that contain acid components form the main chain of the polymer resin. The polymer resin used is a polymer resin that can be formed into a film by a solution film formation method and contains acid structural units in the main chain. Note that a structural unit is a unit of chemical structure that can describe a polymer chain or polymer molecule by repetition or combination in the main chain of the polymer resin.

As the polymer resin, either synthetic or natural resins can be used as long as they are polymer resins that can be formed into a film by a solution film formation method and contain multiple acid constituent units, such as cellulose ester resin, polyimide resin, acrylic resin, etc. Acid constituent units containing acid components may be contained in the manufactured resin itself, and the content of acid components may vary depending on the lot during resin production. In addition, acid components may be generated in the resin material or the resin itself over time, causing the acid components to be contained in the resin.

Examples of the acid components contained in the acid structural unit include carboxyl groups. In the case of polyimides soluble in organic solvents, if the reaction during the imidization reaction of the polyimide is insufficient, carboxyl groups may remain as part of the polymer's main chain structure. In addition, depending on the pulp raw material of the cellulose acylate, hemicellulose components containing carboxyl groups are contained as part of the repeating units of the polymer. Therefore, the effects of promoting peelability are better exhibited when cellulose ester resins made from pulp, commonly used polyimide resins, and acrylic resins are used as polymer resins.

The acid constituent units are preferably contained in a composition ratio of 0.4% to 5% based on the entire polymer resin. More preferably, it is contained in a range of 0.6% to 4%, and even more preferably, it is contained in a range of 1% to 3.5%. When the acid constituent units are contained in the above range, a synergistic effect with the organic compound added to the resin composition for film is more preferably exhibited, and the peelability from the support metal during film production is improved. The composition ratio of the acid constituent units is a value calculated from the type and amount of acid constituent units such as carboxyl groups and the composition of the polymer resin. The amount of the acid constituent units in the polymer resin may be adjusted so as to obtain the above composition ratio of the acid constituent units.

The case where the polymer resin is a cellulose ester resin composed of cellulose ester will be described. The raw materials for cellulose ester are generally wood pulp and cotton linters. Cellulose ester made from linters contains relatively few acid constituent units, so it is generally unlikely to cause problems with poor releasability due to interactions with the metal support in solution film-forming methods. On the other hand, cellulose ester made from wood pulp contains relatively many acid constituent units, so it is likely to cause problems with poor releasability from the metal support in solution film-forming methods.

When the polymer resin is a cellulose ester resin, the main constituent unit that does not contain an acid component is a cellulose derivative, and the acid constituent unit that contains an acid component is a hemicellulose derivative. Therefore, cellulose esters made from wood pulp contain a relatively large amount of hemicellulose derivatives. The resin composition for films of the present invention is particularly effective in peeling during production when a cellulose ester resin is used as the polymer resin, and when the cellulose ester is derived from pulp.

The pulp that can be used is any pulp that is commonly used as a raw material for cellulose esters, for example, broadleaf trees such as oak and eucalyptus, or softleaf trees such as radiata pine and spruce.

In the cellulose ester resin, the main structural unit which is a cellulose derivative can be, specifically, various cellulose esters having an aliphatic acyl group. For example, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate are preferred. Because of their excellent properties such as transparency, it is preferable to use cellulose acylate such as cellulose triacetate. These cellulose esters can be used alone or in combination of two or more.

The acyl group of cellulose acylate is not particularly limited, and may be an acetyl group with one carbon atom, or may be one with two or more carbon atoms. The acyl group with two or more carbon atoms may be an aliphatic group or an aryl group, such as an alkyl carbonyl ester, alkenyl carbonyl ester, aromatic carbonyl ester, or aromatic alkyl carbonyl ester of cellulose, each of which may further have a substituted group. Examples of such groups include a propionyl group, a butanoyl group, a pentanoyl group, a hexanoyl group, an octanoyl group, a decanoyl group, a dodecanoyl group, a tridecanoyl group, a tetradecanoyl group, a hexadecanoyl group, an octadecanoyl group, an iso-butanoyl group, a t-butanoyl group, a cyclohexanecarbonyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, and a cinnamoyl group.

The average degree of substitution of acyl groups in cellulose acylate (hereinafter referred to as the degree of substitution of acyl groups) is preferably in the range of 1.5 to 3, more preferably in the range of 2 to 2.97, and even more preferably in the range of 2.5 to 2.97. Theoretically, the upper limit of the degree of substitution of acyl groups is 3.00, but it is difficult to synthesize cellulose acylate with an acyl substitution degree exceeding 2.97. For this reason, the degree of substitution of acyl groups in cellulose acylate used as a polymer resin is set to 2.97 or less. As is well known, the degree of substitution of acyl groups is the proportion of hydroxyl groups of cellulose esterified with carboxylic acid, that is, the degree of substitution of acyl groups.

The degree of acyl group substitution can be determined by a conventional method. For example, the degree of acetylation (degree of acetyl group substitution) is determined according to the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (Testing method for cellulose acetate, etc.). It can also be measured by measuring the distribution of the degree of acetylation (degree of acyl group substitution) by high performance liquid chromatography. As an example of this method, the degree of acetylation of cellulose acetate is measured by dissolving the sample in methylene chloride, using a column "Novapac phenyl (Waters)", measuring the acetylation distribution by a linear gradient from the eluent mixture of methanol and water (methanol:water mass ratio 8:1) to a mixture of dichloromethane and methanol (dichloromethane:methanol mass ratio 9:1), and comparing it with a calibration curve of standard samples with different degrees of acetylation. These measurement methods can be determined by referring to the method described in JP-A-2003-201301.

In the cellulose ester resin, the acid constituent unit which is a hemicellulose derivative may be one contained in a cellulose ester made from pulp as a raw material. For example, depending on the type of constituent sugar, mannan, β-1,3-1,4-glucan, xylan, xyloglucan, etc. may be mentioned. These hemicellulose derivatives often have acid components such as side chains, and mannan, xylan, etc. also have acid components. Furthermore, the cellulose ester resin may contain acid components other than hemicellulose derivatives due to pulp bleaching, etc. These hemicellulose derivatives may be of any type, and may be one type or two or more types. Furthermore, when multiple types of hemicellulose derivatives are contained, they can be used regardless of the composition ratio of each type of hemicellulose.

The amount of each hemicellulose derivative contained in cellulose ester resin can be measured by high performance liquid chromatography (HPLC). For example, pulp made from a blend of oak, poplar, gum, maple, etc. contains about 0.20% mannan, which is a hemicellulose, and about 1.00% xylan, based on the entire cellulose ester resin.

The type of hemicellulose contained in cellulose ester resin can be measured by the following method. For example, the ratio of mannose to xylose in the hemicellulose contained in cellulose ester resin can be measured by the following method. Accurately weigh 200 mg of dried sample, add 3 ml of 72% sulfuric acid, and completely dissolve the sample over 2 hours using ultrasonic waves while cooling with ice water. Add 37 ml of distilled water to the resulting solution, shake thoroughly, reflux at 106°C under a nitrogen stream for 4 hours, and then leave to stand for 30 minutes. Next, add 10 mL of the resulting solution to 14 g of barium carbonate, and neutralize by applying ultrasonic waves while cooling with ice water. Filter the supernatant, confirm that the pH is about 5.5 to 6.5, and place in an HPLC vial. Analyze the sample by high performance liquid chromatography under the following conditions.

Measurement equipment: High performance liquid chromatography (HPLC)
Detector: CAD
Column: Shodex (registered trademark) Asahipak NH2-50 4E (4.6φ×250 mm) (manufactured by Showa Denko K.K.)
Eluent: acetonitrile (700 mL) / ultrapure water (300 mL)
Flow rate: 0.9 ml/min Column temperature: 10° C.
Injection volume: 20 μL
Measurement time: 40 minutes

The number average molecular weight Mn is not particularly limited, but is preferably within the range of 70,000 to 110,000. In this specification, the number average molecular weight Mn is measured using a high performance liquid chromatography system in which a detector for detecting refractive index and light scattering is connected to a gel filtration column. As the high performance liquid chromatography system, for example, Shodex (registered trademark) GPC SYSTEM-21H (manufactured by Showa Denko K.K.) can be used. As the detector, for example, a differential refractive index detector (RI) can be used. An example of the measurement conditions for such gel permeation chromatography is as follows:

Solvent: dichloromethane Column: TSKgel (registered trademark) GMHXL (7.8 x 300 mm), two columns (manufactured by Tosoh Corporation)
Guard column: TSKgel (registered trademark) guard column HXL-H (manufactured by Tosoh Corporation)
Sample concentration: 2000 ppm
Flow rate: 0.8 mL/min
Sample injection volume: 100 μL
Standard samples: PMMA (Poly Methyl Methacrylate) (molecular weight: 1850, 7360, 29960, 79500, 201800, 509000, 625500)
Column temperature: 28 ° C.

When the polymer resin is a cellulose ester resin, the acid constituent units are preferably contained in a range of 0.4% to 5% in terms of composition ratio based on the entire polymer resin. The composition ratio of the acid constituent units can be calculated from the polymer units contained in the polymer resin. A polymer unit is a unit of a polymer molecule that constitutes a polymer resin, and in the case of a cellulose ester resin, the polymer unit can be considered to be a cellulose ester having a molecular weight. In a cellulose ester resin, the composition ratio of the acid constituent units can be calculated from the composition ratio of mannan and xylan, which are hemicelluloses that constitute the acid constituent units in the cellulose ester, which is a polymer unit, and this composition ratio and the number average molecular weight of the entire cellulose ester resin can be used to determine the composition ratio of the acid constituent units.

For example, if the number average molecular weight of a cellulose ester resin is 90,000, and the hemicellulose contains 0.20% mannan and 1.00% xylan in a composition ratio, totaling 1.20%, the acid constituent units of the hemicellulose can be considered to be mannan and xylan, and the ratio of the acid constituent units can be 1.20% based on the entire cellulose ester resin. In addition, based on the composition and number average molecular weight of the cellulose ester, and the composition of the mannan and xylan, the number of components of the acid constituent units in the cellulose ester, which is a polymer unit, can be set to an average of 6.7 in the cellulose ester resin.

The number of components of the acid constituent units in the cellulose ester, which is a polymer unit, is not particularly limited, but is preferably within the range of, for example, 1.0 to 20. By having the acid constituent units within the above range, a synergistic effect with the organic compound added to the resin composition for film is more preferably exerted, and the peelability from the support metal during film production is improved.

In addition, when carboxyl groups are present as acid components due to bleaching of pulp or cellulose containing mannose units, which are mannans and xylose units, which are hemicellulose derivatives, and xylose units, which are xylan, the carboxyl group concentration per 100 g of cellulose ester (meq/100 g, cellulose equivalent) is, for example, 0.1 to 2.0, preferably 0.1 to 1.5, more preferably 0.5 to 1.5, even more preferably 0.3 to 1.2, and particularly preferably about 0.7 to 1.2, and may be, for example, 0.4 to 1.5, or, for example, about 0.4 to 0.9.

The carboxyl group content in cellulose ester (in terms of cellulose) can be calculated, for example, by adsorbing methylene blue to the carboxyl groups of the cellulose ester.

Next, the case where the polymer resin is polyimide will be described. Polyimide is a polymer having imide bonds, and in particular, a polymer containing imide rings having imide bonds in the repeating units of the main chain of the polymer. Polyimide can be suitably used as long as it can be subjected to a solution film forming method. Polyimide is preferably formed from a diamine compound and an acid anhydride compound. Polyimide is preferably soluble in an organic solvent.

When polyimide is produced as a polymer resin, if the reaction during the imidization reaction is insufficient, carboxyl groups may remain as part of the polymer's main chain structure. The reaction during the imidization reaction can be measured by the imidization rate, which allows the proportion of acid constituent units containing acid components to be measured and compared. When the imidization rate is high, the proportion of acid constituent units contained in the polyimide is low and there are few remaining carboxyl groups, and when the imidization rate is low, the proportion of acid constituent units contained in the polyimide is high and there are many remaining carboxyl groups. General polyimides contain some acid components.

When the polymer resin is a polyimide, the acid constituent units are preferably contained in a composition ratio of 0.4% to 5% based on the entire polymer resin. The composition ratio of the acid constituent units in the polyimide can be calculated from the number average molecular weight and the imidization rate. For example, in a polyimide with a number average molecular weight Mn of 180,000, if the imidization rate is 98.5%, the non-imidization rate can be 1.5%, so that the number of acid constituent units in the polyimide, which is a polymer unit, can be determined to be 3.7 based on the composition of the non-imidized carboxyl groups.

The number of components of the acid structural unit in the polyimide (unit: pieces) is not particularly limited, but is preferably within the range of, for example, 1.0 to 20. By having the acid structural unit within the above range, a synergistic effect with the organic compound added to the resin composition for film is more preferably exerted, and the peelability from the support metal during film production is improved.

As the polyimide, aromatic polyimide or alicyclic polyimide can be used, and these can be appropriately selected by using a compound in which the chemical structure of the portion where the acid anhydride compound and the diamine compound are linked is aromatic or alicyclic. The aromatic, alicyclic, or the bond between them can also be substituted with fluorine, hydrocarbon, halogen, hydrophilic group, or the like. The acid anhydride compound and the diamine compound can be selected from the viewpoint of solubility in methylene chloride, which is a solvent, or the glass transition point of the resin, or the physical properties or transparency when made into a film. Of these, alicyclic polyimides or fluorine-substituted polyimides are preferred from the viewpoint of solubility in methylene chloride or film transparency, etc.

The polyimide used in the present invention is preferably a resin that is imidized in the resin state. One method for forming a polyimide film is to form a polyamic acid, which is a reaction between an acid anhydride compound and a diamine compound, into a film and then imidize it by heat. However, this method requires high heat treatment, which places a heavy burden on the production process, and the polyamic acid contains a large amount of hydrophilic components, which makes the resin highly adhesive to metals, and it is prone to insolubilization and coloring after heat treatment, making film processing for optical applications difficult. It is preferable to use a polyimide resin that is imidized in the resin state and has solubility in methylene chloride, because this makes it possible to obtain a transparent, smooth film that can be solution-cast.

The molecular weight of the polyimide resin used in the present invention is preferably in the range of 10,000 to 300,000 in number average molecular weight Mn, and more preferably in the range of 50,000 to 300,000. If the molecular weight is 10,000 or less, the film strength may not be sufficient, and the proportion of molecular ends that tend to be hydrophilic in the polyimide resin may increase, which may increase the resin's adhesion to metals. If the molecular weight is 300,000 or more, it may become difficult to dissolve in a solvent.

Any of these polyimides can be used in the present invention. For example, polyimides synthesized from pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA), or 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6F Examples of suitable polyimides include polyimides synthesized from 6FDA/TFMB (4,4'-(hexafluoroisopropylidene) diphthalic anhydride) and 2,2'-bis(trifluoromethyl)-4,4'-diamino-diphenyl (TFMB or TFDB, 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diamine). More specifically, polyimides made of 6FDA/TFMB can be preferably used in terms of the physical properties of the film. In addition, examples of commercially available products include Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd. and KPI-MX300F manufactured by Kawamura Sangyo Co., Ltd. It should be noted that a mixture of two or more types of polyimides may be used.

Next, the case where the polymer resin is an acrylic resin will be described. There are no limitations on the acrylic resin as long as it can be used for solution film formation, and it is a polymer of an acrylic acid ester or a methacrylic acid ester. For example, polymers of methyl acrylate (MA) and methyl methacrylate (MMA), or copolymers of these with acrylic acid or methacrylic acid, are preferable.

Acrylic resins have a wide range of acid values depending on the carboxyl groups contained in the raw monomers. In addition, carbonyl compounds may be added due to deterioration. Acid can also be introduced by copolymerizing an acid monomer into acrylic resin. It can be said that acrylic resins are commonly used as resins that contain acid.

Specific examples of acid monomers include acrylic acid and methacrylic acid. Commercially available products of this type of acid-containing acrylic resin include "DIANAL (registered trademark) BR73" (acid value: 3.3 mg (KOH)/g) manufactured by Mitsubishi Rayon Co., Ltd.

When the polymer resin is an acrylic resin, the acid constituent units are preferably contained in a composition ratio of 0.4% to 5% based on the entire polymer resin. The composition ratio of the acid constituent units in the acrylic resin can be calculated from the raw materials, the composition of the polymer unit, the acid value, etc. For example, an acrylic resin with a composition ratio of MMA and MA of 95:5 containing 1% acrylic acid and a number average molecular weight Mn of 100,000 has a composition ratio of 1.0% acid constituent units, so the number of acid components in the polymer unit can be set to an average of 10.1.

The number of components of the acid structural unit in the acrylic resin (units: pieces) is not particularly limited, but is preferably within the range of, for example, 1.0 to 20. By having the acid structural unit within the above range, a synergistic effect with the organic compound added to the resin composition for film is more preferably exerted, and the peelability from the support metal during film production is improved.

The molecular weight of the acrylic resin used in the present invention is preferably in the range of 10,000 to 200,000 in number average molecular weight Mn, and more preferably in the range of 50,000 to 100,000. If the molecular weight is 10,000 or less, the film strength may not be sufficient, and the proportion of molecular ends that tend to be hydrophilic in the acrylic resin may increase, which may increase the resin's adhesion to metals. If the molecular weight is 200,000 or more, it may become difficult to dissolve in a solvent.

The above polymer resins may be used alone or in combination of two or more. When using two or more polymer resins, for example, the same type of polymer resins with different molecular weights or the same type of polymer resins with different copolymer compositions can be appropriately selected and used from the viewpoints of the solubility or drying property of the solution, or the physical properties or transparency of the film.

The resin composition for films of the present invention contains an organic compound that contains a phosphate group and has acid dissociability. The organic compound is contained as an additive. The organic compound preferably has an acid value (unit: mg(KOH)/g) in the range of 40 to 300 as measured by the acid value measurement method for chemical products according to JIS K0070-1992. More preferably, it is in the range of 60 to 250, and even more preferably, it is in the range of 100 to 200. If it is in this range, it is preferable because the peelability is good and the transparency of the film is high (low haze).

Examples of organic compounds that contain a phosphate group and have acid dissociability include various types of phosphoric acid. The phosphoric acid is preferably at least one of the compounds represented by the following general formula (1) or (2).

In the above formula (1) or (2), _R1 is an alkyl group having 1 to 20 carbon atoms, _R2 is an alkyl group having 1 to 20 carbon atoms, _R3 is an alkyl group having 1 to 6 carbon atoms, n is a natural number of 1 to 8, X is a hydroxy group, and Y and Z are each one of a hydroxy group, an alkoxy group, and oxygen.

Specific compounds include those in which R ₁ is an alkyl group having 12 carbon atoms (represented as lauryl (C12) in Table 1) (lauryl phosphate, Phosphanol, ML-200), R 1 is oxygen and R ₂ is an alkyl group having 12 carbon atoms (represented as lauryl (C12) in Table 1), R ₃ is ethylene and n is any one of 1 to 8 (polyoxyethylene lauryl phosphate ester, Plysurf A208B, Plysurf A219B), R ₁ is oxygen and R ₂ is an alkyl group having 10 carbon atoms (represented as C10 in Table 1), R ₃ is ethylene and n is any one of 1 to 8 (polyoxyethylene tridecyl ether phosphate ester, Plysurf A212C, Plysurf A215C), R ₁ is oxygen and R ₂ is a 2-ethylhexyl group (represented as (C8) in Table 1 because it has 8 carbon atoms), and R Examples include those in which R ₁ is oxygen and R ₂ is a styrenated phenyl group (having _{8 carbon atoms, hence indicated as (C8) in Table 1), and those in which R 3} _is ethylene and n is any one of 1 to 8 (polyoxyethylene styrenated phenyl ether phosphate, Plysurf A208F).

In Table 1, the compound number, _R1 , _R2 , _R3 , acid value, and product name are shown for each of the above compounds. In the table, "-" is entered where there is no corresponding item. As described above, the acid value is a value determined by the acid value measurement method according to Japanese Industrial Standard JIS K0070-1992, and the unit is (mg(KOH)/g).

The resin composition for films of the present invention preferably contains the organic compounds exemplified above in an amount of 0.01 to 10 parts by mass relative to 100 parts by mass of the polymer resin. More preferably, the amount is in the range of 0.02 to 5 parts by mass, and even more preferably, in the range of 0.03 to 3 parts by mass. In particular, when the polymer resin is made of a cellulose derivative, the organic compound is preferably contained in an amount of 0.01 to 1 part by mass relative to 100 parts by mass of the polymer resin. Furthermore, when the polymer resin is made of a polyimide resin, the organic compound is preferably contained in an amount of 0.05 to 5 parts by mass relative to 100 parts by mass of the polymer resin. Furthermore, when the polymer resin is made of an acrylic resin, the organic compound is preferably contained in an amount of 0.05 to 5 parts by mass relative to 100 parts by mass of the polymer resin. By containing the organic compound within these ranges, a peeling promotion effect is achieved when a film in which each resin composition for films containing various polymer resins is cast is peeled off from a support, and the peeling surface of the film after peeling off from the support is good.

The resin composition for film of the present invention contains a solvent. The solvent is preferably a halogenated hydrocarbon. 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 chlorine-based solvents that can be used include methylene chloride, chloroform, 1,2-dichloroethane, and 1,1,2,2-tetrachloroethane, and methylene chloride is used in this embodiment. 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, and in this embodiment, only methylene chloride is used as the solvent. Since methylene chloride, a chlorine-based solvent, is used as the solvent, the polymer resin dissolves in the solvent at a mass ratio sufficient to form a dope in the solution film formation method even at room temperature. Since the solubility of the polymer resin is good, a film with excellent transparency can be obtained.

A monohydric alcohol having a carbon number in the range of 1 to 3 may be added to methylene chloride. Examples of such monohydric alcohol include methanol, ethanol, and 1-propanol. Methanol is preferably used. By adding a monohydric alcohol, particularly when a film is produced by a solution casting method, the dope made of the resin composition for film adheres to the metal lip of the casting die and hardens, which makes it extremely difficult to remove, causing surface defects such as streaks in the film, and the peeling problem of the load required in the process of peeling the film from the metal support (band) on which the dope is cast becomes very high.

The mixing ratio of monohydric alcohol to methylene chloride is preferably within the range of 0.5% to 10% by mass relative to the total solvent including methylene chloride and monohydric alcohol. More preferably, it is within the range of 1% to 5%, and even more preferably, it is within the range of 1% to 3%. By being within this range, the transparency of the solution-cast film 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.

When methylene chloride is used as the solvent, a polymer resin that dissolves in methylene chloride at a mass percent concentration of 10% or more is preferably used. A polymer resin that dissolves at 15% or more is more preferably used, and a polymer resin that dissolves at 20% or more is even more preferably used. This is because a smooth film can be obtained in solution casting when at least 10% of the polymer resin is dissolved.

The resin composition for films may contain various additives such as plasticizers, UV absorbers, fine particles, or anti-degradants, in addition to polymer resins and organic compounds added to a solvent consisting of methylene chloride and a monohydric alcohol.

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

The silica fine particles are preferably surface-modified (modified) with TMS (trimethylsilyl) groups. Surface modification is a hydrophobic treatment, and as is commonly done, silica fine particles are treated with HMDS (hexamethyldisilazane) or TMCS (trimethylsilyl chloride). As a result, the silanol groups on the silica surface are trimethylsilylated and hydrophobic groups are introduced, resulting in a hydrophobic treatment. The surface coverage rate of trimethylsilyl groups on the silica is preferably in the range of 0.005 to 0.120. More preferably, it is in the range of 0.008 to 0.050, and even more preferably, it is in the range of 0.012 to 0.030. A surface coverage ratio in the range of 0.005 to 0.120 is preferable because it suppresses surface scattering, ensures transparency, and prevents films from adhering to each other.

The surface coverage is calculated by dividing the carbon content in the fine particles by the specific surface area. That is, the surface coverage is calculated by RC/S, where RC is the carbon content of the fine particles and S is the specific surface area. The carbon content RC is calculated by elemental analysis using a combustion method (for example, a fully automatic elemental analyzer manufactured by PerkinElmer Japan Co., Ltd.). The specific surface area S is measured according to the BET method (the adsorption theory method by Brunauer, Emmett, and Teller). The silica fine particles preferably have a specific surface area of 20 m ² /g or more and 400 m ² /g or less, more preferably 50 m ² /g or more and 300 m ² /g or less, and particularly preferably 70 m ² /g or more and 150 m ² /g or less. This range is preferable because the particle diameter of the silica fine particles can ensure transparency and suppress adhesion between films.

Next, the method for producing the film will be described. The method for producing the film includes a casting process, a peeling process, and a drying process. In the casting process, a dope made of a resin composition for the film is cast onto a metal support to form a cast film. In the peeling process, the cast film is peeled off from the support to form a film. In the drying process, the film is dried in stages.

The film manufacturing equipment 20 shown in FIG. 1 is an example of equipment for manufacturing a film 10, and the film manufacturing method will be described using this example. The film manufacturing equipment 20 includes a dope preparation device 22 and a film manufacturing device 23. The dope preparation device 22 is for preparing a 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 in this order from the upstream side by piping 33.

The mixing tank 26 is for dissolving the polymer resin 11 and the organic compound 12 in the solvent 15 by mixing the raw materials of the dope 21, the polymer resin 11, the organic compound 12, and the solvent 15. First, in the mixing tank 26, the solvent 15 is adjusted by mixing methylene chloride with methanol, which is a monohydric alcohol (solvent adjustment process). The polymer resin 11 and the organic compound 12 are added to the mixing tank 26 containing the solvent 15.

In this embodiment, the polymer resin 11 supplied to the mixing tank 26 is a powder, but the form of the polymer resin 11 is not limited to a powder, and may be, for example, a flake or pellet shape. The mixing tank 26 is equipped with a stirring mechanism (not shown) that stirs the mixture of the polymer resin 11, the organic compound 12, and the solvent 15 that has been introduced, thereby promoting dissolution. The stirring mechanism in this embodiment is a stirring blade contained in the mixing tank and a drive unit that rotates and drives the stirring blade. However, the stirring mechanism is not particularly limited as long as it is a mechanism that stirs the mixture of the polymer resin 11, the organic compound 12, and the solvent 15. The polymer resin 11 and the organic compound 12 are dissolved in the solvent 15 by being mixed with the solvent 15 in the mixing tank 26, and the dope 21 is produced. The organic compound 12 has excellent solubility in the solvent 15 and also has excellent compatibility with the solution in which the polymer resin 11 is dissolved in the solvent 15, so that a film 10 with excellent transparency is obtained.

It is also preferable to heat-dry the polymer resin 11 to be supplied to the mixing tank of the present invention to reduce the moisture content of the resin before supply. The resin of the present invention may absorb moisture. For example, in the case of polyimide, the moisture content may be in the range of 2% to 4%. If the polymer resin 11 is made into a solution while its moisture content is high, the solution may become cloudy or the transparency of the film may deteriorate. In addition, fluctuations in the moisture content of the resin may cause fluctuations in the resin concentration, drying during casting, or peelability. The heating temperature for the heating and drying of the polymer resin 11 of the present invention is preferably in the range of 100°C to 180°C, more preferably in the range of 120°C to 160°C. The heating time is preferably in the range of 5 minutes to 240 minutes, more preferably in the range of 20 minutes to 180 minutes. The moisture content of the resin after heating and drying is preferably 1% or less, more preferably 0.7% or less.

The mixing tank 26 may be equipped with a temperature control mechanism (not shown) for controlling the internal temperature. The mixing tank 26 of this embodiment is also equipped with a temperature control mechanism, and the temperature of the mixture is maintained at room temperature (approximately in the range of 25°C to 30°C). Depending on the types of polymer resin 11, organic compound 12, and solvent 15 used, the temperature of the mixture is controlled by the temperature control mechanism, so that dissolution is promoted and deterioration and/or foaming are suppressed. For example, when methylene chloride is used as the solvent 15, it is preferable to set the temperature at 39°C or less under normal pressure, which suppresses foaming. 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 to 39°C, even more preferably in the range of 15°C to 37°C, and particularly preferably in the range of 25°C to 35°C. However, depending on the types of polymer resin 11, organic compound 12, and solvent 15 used, dissolution may occur without temperature control, in which case a temperature control mechanism may not be provided.

If the various additives mentioned above are to be included in the film 10, these additives may be introduced into the mixing tank 26. In this way, the raw materials of the dope 21 mixed in the mixing tank 26 are not limited to the polymer resin 11, the organic compound 12, and the solvent 15.

Some raw materials may contain impurities, or may remain as insoluble matter without being dissolved by stirring in the mixing tank 26. In this embodiment, the dope 21 is sent from the mixing tank 26 to the filter 28 by the pump 27, and these foreign matters are removed by the filter 28. As the filter 28, a filter paper (63LS manufactured by Toyo Roshi Kaisha, Ltd.) with a pore size of 20 μm is used, but the pore size and material are not limited to this example and may be determined according to the use of the film 10, or the types of the polymer resin 11, the organic compound 12, and the solvent 15. The pore size of the filter paper used as the filter 28 is preferably in the range of 5 μm to 100 μm, more preferably in the range of 10 μm to 50 μm, and even more preferably in the range of 10 μm to 25 μm.

Other filters include metal filters, the pore size of which is preferably in the range of 3 μm to 15 μm, more preferably in the range of 3 μm to 10 μm, and even more preferably in the range of 3 μm to 5 μm. When using a metal filter with such a pore size, the metal filter may be disposed downstream of filter 28, and filtration may be performed in two stages. Such staged filtration is particularly effective when manufacturing optical films.

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

The dope 21 filtered by the filter 28 is guided to the storage tank 31, where it is stored until it is used for casting. The storage tank 31 is preferably equipped with a stirring mechanism (not shown), and in this embodiment, it is equipped with a stirring mechanism having a similar configuration to the stirring mechanism of the mixing tank 26. This stirring mechanism more reliably maintains the uniformity of the dope 21 until it is used for casting. In this example, there is one storage tank 31, but there may be multiple storage tanks. When there are multiple storage tanks 31, the multiple storage tanks 31 may be connected in series or in parallel.

The mixing tank 26, the filter 28, and the storage tank 31 are each preferably provided with a light-shielding member that blocks light from entering the interior, and are provided in this embodiment as well. For example, the mixing tank 26 has a tank body that contains the mixture formed from a material with a light-shielding function, and a lid is provided on the top of the tank body as a light-shielding member that also has a light-shielding function. When using a polymer resin 11 that undergoes denaturation, reaction, etc. due to light, such a light-shielding member can suppress these.

The downstream end of the pipe 33 is connected to the casting die 36 of the film manufacturing device 23, and the dope 21 in the storage tank 31 is sent to the casting die 36 by the pump 32. When manufacturing a film 10 with a single-layer structure, the dope 21 used for casting preferably has a polymer resin 11 concentration in the range of 15% to 30% by mass percent, and in this embodiment, it is 20%. By making it 15% or more, the viscosity of the dope coming out of the casting die 36 (corresponding to pressure loss) is more easily ensured than when it is less than 15%. Also, by making it 30% or less, when the solvent 15 is methylene chloride, the polymer resin 11 is more reliably dissolved in the solvent 15, and the dope 21 is more reliably prevented from becoming cloudy, compared to when it is greater than 30%.

When producing the film 10, the concentration of the polymer resin 11 is preferably in the range of 15% to 25% by mass percent, and more preferably in the range of 15% to 23% by mass percent. Even if the concentration of the polymer resin 11 is in the range of 8% to less than 15%, the dope 21 can be cast by using, for example, a Geesa (preferably a G-type Geesa). When the polymer resin 11 is polyimide, the concentration of the polyimide is more preferably in the range of 20% to 30% by mass percent.

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

In the film manufacturing method of the present invention, in the casting process, the dope 21 is continuously cast onto a moving support, and in the peeling process, the cast film is continuously peeled off from the support. Therefore, the film manufacturing apparatus 23 manufactures the film 10 from the dope 21. The apparatus includes a casting unit 37, a tenter 38, a roller dryer 41, a slitter 42, and a winder 43, in this order from the upstream side. The casting unit 37 includes a band 46 formed into an annular shape as a support, a pair of rollers 47 that support the band 46 and run it in the longitudinal direction, a casting die 36, and a peeling roller 48. At least one of the pair of rollers 47 is rotated in the circumferential direction by a driving mechanism (not shown), and this rotation causes the band 46 wrapped around the pair of rollers 47 to circulate and run in the longitudinal direction. In this example, the casting die 36 is disposed above one of the pair of rollers 47, but it may be disposed above the band 46 between one and the other of the pair of rollers 47.

The casting die 36 is a discharge part that continuously discharges the supplied dope 21 from a discharge port 36a facing the band 46. By continuously discharging the dope 21 onto the moving band 46, the dope 21 is cast onto the band 46, and a casting film 51 is continuously formed on the band 46 (casting process). In FIG. 1, the position where the dope 21 comes into contact with the band 46 and the casting film 51 begins to be formed (hereinafter referred to as the casting position) is marked with the symbol PC.

The material of the band 46 is not particularly limited, but metal is preferable, and as a metal, stainless steel (SUS, Steel Use Stainless, stainless steel), in particular hard chrome plated SUS, is preferable. Therefore, the support is preferably a stainless steel band. In this embodiment, the band 46 is made of SUS, which allows the production of a suitable film while favorably exerting the effects of the resin composition for film, etc. Various types of SUS can be used, and SUS316, SUS316L, etc. are preferably used.

The pair of rollers 47 are equipped with a temperature controller (not shown) that adjusts the peripheral temperature. The temperature of the casting film 51 is adjusted via the band 46 by the rollers 47 with the adjusted peripheral temperature. In the case of the so-called drying and gelling method in which the casting film 51 is heated to promote drying and solidified (gelled) by this drying, the peripheral temperature of the rollers 47 is set within a range of, for example, 10°C to 30°C. In the case of the so-called cooling and gelling method in which the casting film 51 is solidified by cooling, the peripheral temperature of the rollers 47 is set within a range of -15°C to 5°C. By this gelling, the casting film 51 is solidified to a degree that it can be transported.

In addition, a drum (not shown) may be used as the support instead of the band 46. In this case, a driving mechanism is provided on the drum, and the drum is rotated in the circumferential direction to form the casting film 51 on the circumferential surface. In this case, the circumferential surface of the drum functions as the surface of the running support. The material of the drum is not particularly limited, but metal is preferable, and as the metal, SUS, particularly SUS plated with hard chrome, is preferable. When a drum is used as the support, the drum is provided with a temperature controller (not shown) for adjusting the circumferential surface temperature, and the temperature of the casting film 51 can be adjusted by adjusting the circumferential surface temperature of the drum. In the case of the dry gelation method, it is preferable to use the band 46 as the support, and in the case of the cool gelation method, it is preferable to use the drum as the support.

A decompression chamber (not shown) may be provided upstream of the dope 21 (the bead) from the casting die 36 to the band 46 in the running direction of the band 46, and is provided in this embodiment as well. This decompression chamber sucks in the atmosphere in the area upstream of the discharged dope 21, and reduces the pressure in this area through this suction. In addition, a blower (not shown) may be provided opposite the band 46 to promote drying of the casting film 51.

After the casting film 51 is hardened on the band 46 to such an extent that it can be transported to the tenter 38, it is continuously peeled off from the band 46 while still containing the solvent. This forms the film 10 (peeling process). The peeling roller 48 is for continuously peeling off the casting film 51 from the band 46. The peeling roller 48 supports the film 10 formed by peeling off from the band 46, for example, from below, and keeps the peeling position PP where the casting film 51 is peeled off from the band 46 constant. The peeling method may be either a method of pulling the film 10 downstream or a method of rotating the peeling roller 48 in the circumferential direction.

Since the dope 21 contains the organic compound 12, the casting film 51 formed on the band 46 also contains the organic compound 12. The organic compound 12 has an acid. Therefore, as presumed above, it is presumed that the acid generated by the acid dissociation from the organic compound 12 preferentially adsorbs to the surface of the band 46, suppressing the polymer resin 11 from adsorbing to the surface of the band 46. Therefore, the peel load of the casting film 51 from the band 46 is suppressed to be small, and as a result, the casting film 51 is peeled off smoothly and continuously from the band 46. Therefore, the film 10 having excellent smoothness of the film surface is obtained. Since the film surface is smooth, the film 10 can be used for an optical film having strict requirements for optical properties. In addition, in the organic compound 12 of this embodiment, when there is a large amount of acid to be dissociated, the peel load of the film 10 is suppressed to be smaller than when there is a small amount of acid.

The mass ratio of the organic compound 12 is approximately equal in the dope 21 and the casting film 51. Therefore, the mass ratio of the organic compound 12 in the casting film 51 or the film 10 is also within the range of 0.01 parts by mass or more and 10 parts by mass or less, assuming that the polymer resin 11 is 100 parts by weight. By making it 0.01 parts by mass or more, the peel load from the band 46 is more reliably kept small compared to when it is less than 0.01 parts by mass. Also, by making it 10 parts by mass or less, a transparent film 10 with less cloudiness is obtained compared to when it exceeds 10 parts by mass.

In the case of the drying and gelling method, the casting film 51 is peeled off from the band 46 while the solvent content of the casting film 51 is in the range of 10% by mass to 100% by mass. In this specification, the solvent content (unit: %) is a value based on the dry weight, and specifically, it is a percentage calculated by {M15/(M10-M15)} x 100, where M15 is the mass of the solvent 15 and M10 is the mass of the film 10.

The casting film 51 contains the organic compound 12, which is an organic compound containing a phosphate group and having acid dissociability, and therefore the peel load of the casting film 51 from the band 46 is reduced by the above-mentioned presumed effect on the interaction between the surface of the band 46 and the polymer resin 11. Also, the improved peelability allows the running speed of the band 46 to be increased, and therefore the production efficiency of the film 10 is improved. Furthermore, the improved peelability not only improves the surface condition of the peeled surface of the film 10, but also stabilizes the peeling position, thereby preventing problems with the surface condition of the surface opposite the peeled surface.

As described above, the casting unit 37 forms the film 10 from the dope 21. The band 46 travels between the casting position PC and the peeling position PP in a circular manner, so that the casting of the dope 21 and the peeling of the cast film 51 are repeatedly performed.

A blower (not shown) for drying the film 10 may be provided in the transport path between the casting unit 37 and the tenter 38. The peeled film 10 is guided to the tenter 38. The tenter 38 includes clips 52 for holding the sides of the long film 10, a pair of rails (not shown), and a chain (not shown). Instead of the clips 52, a pin plate (not shown) may be used in which multiple pins (not shown) are arranged upright on the top surface of a table, and the film 10 is held by piercing each pin into the side of the film 10.

The rails are installed on the sides of the transport path for the film 10, and the pair of rails are spaced apart. The chain is hung over a driving sprocket and a driven sprocket (not shown) and is attached so as to be freely movable along the rails. The clips 52 are attached to the chain at predetermined intervals, and as the driving sprocket rotates, the clips 52 move in a circular motion along the rails. The clips 52 begin to hold the film 10 that has been guided near the entrance of the tenter 38, move toward the exit, and release their hold near the exit. After releasing their hold, the clips 52 move again near the entrance and hold the newly guided film 10. In this way, the clips 52 transport the film 10 in the longitudinal direction while gripping each side of the film 10.

By changing the track of the rail, the travel path of the clip 52 can be changed. This allows the film 10 to be stretched in a direction intersecting the longitudinal direction (e.g., width direction) during transport.

The tenter 38 is provided with a blower 53 above the transport path of the film 10. An outlet (not shown) for letting out dry gas is formed on the underside of the blower 53, and the dry gas (e.g., air) is blown toward the passing film 10. The temperature of the dry gas from the blower 53 is preferably within the range of 40°C or higher and 200°C or lower. A blower having a similar structure may be provided below the transport path of the film 10. As the tenter 38 has the blower 53, the film 10 can be dried even while passing through the tenter 38 (first drying step). However, there are cases where the tenter 38 is not provided.

The roller dryer 41 includes multiple rollers 41a and an air conditioner (not shown). The multiple rollers 41a support the film 10 on their circumferential surfaces. The film 10 is wound around the rollers 41a and transported. The air conditioner adjusts the temperature, humidity, and other factors inside the roller dryer 41. The temperature inside the roller dryer 41 is preferably within the range of 80°C to 160°C. The humidity inside the roller dryer 41 is preferably within the range of 0% to 50% relative humidity. The film 10 continues to dry while passing through this roller dryer 41 (second drying process).

The slitter 42 is for cutting off each side edge of the film 10. By this cutting, the film 10 is made to have, for example, a desired product width. A slitter with the same configuration as the slitter 42 may be arranged at other positions. For example, between the casting unit 37 and the tenter 38, and/or between the tenter 38 and the roller dryer 41. When the slitter 42 is arranged between the casting unit 37 and the tenter 38, the side edge of the film 10 moving from the casting unit 37 to the tenter 38 is cut off just before being introduced into the tenter 38, so that, for example, the clip 52 can hold the film 10 more reliably. When the slitter 42 is arranged between the tenter 38 and the roller dryer, the clip 52 can cut off the trace of the clip 52, so that the transport by the roller 41a can be more stable. The cut off side edge is guided to a crusher (not shown), where it is crushed into chips, and may be used as a raw material for a new dope 21.

The winding machine 43 is used to wind the film 10 into a roll. The winding machine 43 is equipped with a motor (not shown), and a winding core 54 is set in the winding machine 43. The film 10 is wound around the winding core 54 as the winding core 54 rotates due to the motor.

The wound film 10 is produced from a dope 21 made of a resin composition for films, and contains the polymer resin 11 and organic compound 12 as described above. Because it contains both of these, due to the presumed action described above, it has good peelability from the band 46, and the peeling speed can also be improved. In addition, because it has good peelability, the surface condition of the film itself is good.

As described above, the organic compound 12 and various additives other than the organic compound 12 are not limited to being mixed with the polymer resin 11, etc., in the mixing tank 26. For example, an addition pipe (not shown) for guiding at least a portion of these additives may be connected so as to join the pipe 33, and the additives may be added in the pipe 33. In that case, mixing may be performed by providing a well-known static mixer (e.g., a through-the-pipe mixer, etc.) in the pipe 33.

The film 10 is not limited to a single-layer structure, but may be a multi-layer structure. In the case of a multi-layer structure, the number of layers is not limited to two, but may be three or more.

The film 10 of the present invention has the same composition as the resin composition for film used in its production. Therefore, the film 10 contains a polymer resin that contains multiple main structural units that do not contain an acid component and multiple acid structural units that contain an acid component, and an organic compound that contains a phosphate group and has acid dissociability.

Furthermore, in the film 10, the organic compound is preferably contained in a range of 0.01 parts by mass to 10 parts by mass to 100 parts by mass of the polymer resin. Furthermore, in the polymer resin, when averaging a plurality of polymer units, it is preferable that the repeating units that are acid components out of all the repeating units in the polymer units are in a range of 0.4% to 5%.

Since the film 10 is constructed as described above, when the film 10 is produced by the solution casting method, the film 10 is produced in a state where it has good peelability. Therefore, the film 10 has a good surface condition. Furthermore, the organic compound 12 contained in the resin composition for film does not deteriorate the performance of the film 10. For example, the film 10 can be made to have a reduced effect on the haze of the film 10 and be applicable to optical applications. For example, the film 10 has a haze of 2.0 or less as measured based on JIS K7136. More preferably, the haze is 1.5 or less.

The thickness of the film 10 is not particularly limited as long as it is within a range in which the film 10 can be suitably produced by a solution casting method using a resin composition for film, and can be set appropriately depending on the application. When used as an optical film, the thickness is preferably in the range of 10 μm to 60 μm. For example, when used as a cover film for a mobile display, the thickness is preferably in the range of 10 μm to 50 μm, and when used as a diaphragm for earphones, etc., the thickness is preferably in the range of 5 μm to 15 μm. In this embodiment, the film 10 can be produced without problems if the thickness is in the range of 5 μm to 150 μm. However, it is not limited to this range, and the thickness of the film 10 may be thicker than 150 μm or thinner than 5 μm depending on various adjustments.

The following are examples of the present invention. Films 10 were produced using film production equipment 20, resulting in Examples 1 to 22. The polymer resins used were cellulose ester resin, polyimide resin, and acrylic resin.

The cellulose ester resin used in the examples was a cellulose acylate resin, and the raw material was various pulps. The cellulose acylate resins used are listed in Table 2. The types of cellulose acylate resins used are listed in the "Cellulose Acylate Resin" column of Table 2 as "CA-1" to "CA-7". The raw materials for each cellulose acylate resin are listed in the "Raw Material" column of Table 2. "Pulp 1" is a hardwood and is a blend of oak, poplar, gum, and/or maple, "Pulp 2" is a hardwood and is oak, "Pulp 3" is a hardwood and is eucalyptus, "Pulp 4" is a softwood and is radiata pine, and "Pulp 5" is a softwood and is spruce. As a reference example, a cellulose ester resin whose raw material is linter was used and named "CA-1".

For each cellulose ester resin, the degree of acylation, number average molecular weight Mn, and ratio of acid constituent units to the entire polymer resin were determined by the above-mentioned method. That is, the ratio of acid constituent units to the entire polymer resin was determined by measuring the composition ratio of mannan and xylan, which are hemicelluloses that are acid constituent units in the polymer unit contained in the polymer resin, as shown in Table 2. Note that a polymer unit is a unit of polymer molecules that constitute a polymer resin, and a polymer resin is composed of multiple polymer molecules. In addition, the average number of acid components in the polymer unit was calculated from this composition ratio and the number average molecular weight. In Table 2, the composition ratio, which is the composition ratio of mannan and xylan, which are hemicelluloses, is listed in the "hemicellulose composition ratio" column, the ratio of acid constituent units in the polymer unit is listed in the "acid constituent unit ratio" column, and the average number of acid components in the polymer unit is listed in the "number of components in polymer unit (average)".

The polyimide resins used in the examples were 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (TFMB, 2,2'-Bis(trifluoromethyl)benzidine) as "PI-1" and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride) as "PI-2". "PI-1" has a molecular weight of approximately 320 and is represented by the following formula (3), and "PI-2" has a molecular weight of approximately 444.24 and is represented by the following formula (4).

The number average molecular weight and imidization rate of "PI-1" and "PI-2" are shown in Table 3. In addition, the ratio of acid constituent units contained in the polymer resin was calculated based on the number average molecular weight and imidization rate, with the entire polymer resin as the standard. In addition, the average number of acid components in the polymer units contained in the polymer resin was calculated from the ratio of acid constituent units, and is shown in Table 3.

The acrylic resins used in the examples were "MA-1" a resin made of a copolymer of MMA and MA (composition ratio 95:5) and acrylic acid (1% of the total resin), and "MA-2" a commercially available product, "Dianal BR73" (manufactured by Mitsubishi Chemical Corporation). The number average molecular weight, the ratio (%) of acid constituent units in the polymer unit, and the average number (pieces) of acid components in the polymer unit are shown in Table 4.

The compounds used as organic compound 12 were those shown as "PA-1" to "PA-7" in Table 1 above.

The dope 21 containing the resin composition for film to be supplied to the film manufacturing equipment 20 contains 100 parts by mass of polymer resin and the organic compounds in the amounts shown in Table 5. The solvent is dichloromethane, and the concentration of the polymer resin is determined according to each polymer resin.

Details of the casting process, peeling process and drying process are as follows. The casting die and metal lip (die lip) used were made of SUS316L or the like. The dope 21 was passed through the filters 28. First, it was passed through a 30 μm filter, and then through a 10 μm filter. The dope 21 was delivered from the casting die at 1450 cc/min. The band 46 was operated at 5 m/min. Therefore, the casting speed was 5 m/min. The band 46 was made of SUS. Drying was carried out on the metal band by the film manufacturing equipment 20. After peeling in the peeling process, drying was carried out in the drying process. It was first dried at 50°C, and then dried at 140°C for 10 to 15 minutes. The film was wound onto a fiber-reinforced plastics (FRP) core with a film width of 800 mm and a length of 500 m.

[Example 1] to [Example 6]
In Examples 1 to 6, the cellulose ester "CA-2" was used as the polymer resin 11, and "PA-1", "PA-2", "PA-3", "PA-4", "PA-6", or "PA-7" was used as the organic compound in a ratio of 0.1 parts by mass per 100 parts by mass of the polymer resin, respectively, to produce a single-layer film by the film production equipment 20. The amount of the polymer resin and the organic compound relative to the solvent was 20%. The film production test was performed on the produced film by the method described below. The film production test measured the film thickness, peelability, peel surface condition, and haze. In addition, a separate film was produced, and a peel load test was performed by the method described below. The peel load was measured by the peel load test. The measurement results are shown in Table 5.

[Example 7] to [Example 11]
In Examples 7 to 11, a single-layer film was produced by the film production equipment 20 using the cellulose ester "CA-2" as the polymer resin 11 and "PA-6" as the organic compound in the amounts shown in Table 5. The amount of the polymer resin and the organic compound relative to the solvent was 20%. A film production test was carried out on the produced film by the method described below. In the film production test, the film thickness, peelability, peeled surface condition, and haze were measured. In addition, a separate film was produced, and a peel load test was carried out by the method described below. The peel load was measured by the peel load test. The measurement results are shown in Table 5.

[Example 12] to [Example 16]
In Examples 12 to 16, cellulose esters of "CA-3", "CA-4", "CA-5", "CA-6", or "CA-7" were used as the polymer resin 11, and "PA-4" was used as the organic compound in a ratio of 0.1 parts by mass per 100 parts by mass of the polymer resin, and a single-layer film was produced by the film production equipment 20. The amount of the polymer resin and the organic compound relative to the solvent was 20%. The film production test was performed on the produced film by the method described below. The film production test was performed to measure the film thickness, peelability, peel surface condition, and haze. In addition, a separate film was produced, and a peel load test was performed by the method described below. The peel load was measured by the peel load test. The measurement results are shown in Table 5.

[Comparative Example 1] to [Comparative Example 3] and [Reference Example 1]
In Comparative Examples 1 to 3, cellulose ester of "CA-2" was used as the polymer resin 11, and as the organic compound, in Comparative Example 1, no organic compound was used, in Comparative Example 2, "PA-1(K)" which is a salt of "PA-1" was used, and in Comparative Example 3, "PA-1(K)" which is a salt of "PA-6" was used. "PA-1(K)" and "PA-6(K)" were used at a ratio of 0.1 PHR, and films were produced by the film production equipment 20. "PA-1(K)" and "PA-1(K)" are potassium salts obtained by neutralizing "PA-1" or "PA-6" with potassium hydroxide and then drying. In Reference Example 1, cellulose ester of "CA-1" was used as the polymer resin 11, and a film was produced by the film production equipment 20 without using an organic compound. A film production test was performed on the produced film by the method described below. The film production test was performed to measure the thickness, peelability, peeled surface state, and haze of the film. Separately, a film was formed and a peel load test was carried out by the method described below. The peel load was measured by the peel load test. The measurement results are shown in Table 5.

1. Film Formation Test The thickness of each of the produced films 10 was measured. In addition, the peelability, peeled surface condition, and haze of each of the produced films 10 were measured by the methods described below. The results of each test are shown in Table 5.

(1) Peelability Using the film production equipment 20, the dope 21 was cast onto a metal band made of SUS316 in the same manner as in the above examples, and a film was formed so that the thickness after film formation was 40 μm (Examples 1 to 9 and Examples 12 to 16, Reference Example 1, and Comparative Examples 1 to 3). The film was peeled off from the metal band so that the volatile content was 20%, and then dried and wound up. In Example 10, the film was formed so that the thickness after film formation was 80 μm, and the volatile content was 40%, and then peeled off from the metal band, dried and wound up. In Example 11, the film was formed so that the thickness after film formation was 120 μm, and then peeled off from the metal band, dried and wound up with the volatile content being 60%. The peelability was evaluated from the following viewpoints.

The volatile content is a value based on the dry weight as the amount of volatile content (unit: %), specifically, where the mass of the film 10 for which the amount of residual solvent is to be determined is x and the mass of this film 10 after it has been completely dried is y, it is a percentage calculated by {(x-y)/y} x 100. Note that "completely dried" does not necessarily mean that the amount of residual solvent is strictly "0". For example, in this embodiment, y is the mass of the film 10 to be measured after it has been dried for 3 hours or more in a thermostatic chamber at 120°C or higher and a relative humidity of 10% or lower.

A: Peelability was stable.
B: There was some variation in the peeling position, but it was not a problem for the production of the film.
C: Variation in the peeling position was clearly observed.
D: I couldn't remove it stably.

(2) Surface Condition After Peeling The resulting films 10 were visually observed for step unevenness using reflected light and rated according to the following three-level scale.

A: No step unevenness occurred. B: Step unevenness occurred slightly, but was at a level that did not pose a problem as a product.
C: Significant step unevenness was observed and the product could not be used.

(3) Haze The haze of each of the obtained films 10 was measured and evaluated as the degree of cloudiness. The haze was measured using a haze meter NDH 7000 manufactured by Nippon Denshoku Industries Co., Ltd., based on the Japanese Industrial Standard JIS K 7136. A haze of 2% or less is acceptable, and a haze of 2% or more is unacceptable. A haze of 1% or less is particularly good as the degree of cloudiness of the film.

2. Peel Load Test Using the film production equipment 20, a sample of each of the dopes 21 was cast on a support adjusted to a temperature of 20°C to form a casting film. The support used was made of SUS316 stainless steel. The thickness of the casting film was set so that the thickness of the film sample when dried was 80 μm. The formed casting film was left at room temperature for 2 minutes. Although the casting film was dried compared to the film immediately after casting by this leaving, it was not completely dried. Immediately after this leaving, 13 cutting lines were made in the casting film with a width of 2 cm using a cutter. In one of the 12 cut pieces with a width of 2 cm formed by the cutting lines (first cut piece), one end of the cut piece in the longitudinal direction was held by a clip. The one end of the cut piece was pulled up by the clip 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 lifting was measured by a load cell (UTA-200GR, a small-scale tension-compression type, manufactured by MinebeaMitsumi Inc.) and was taken as the peel load of the first cut piece (first peel load). Thereafter, the peel loads of the remaining 11 cut pieces were measured in the same manner, and were taken as the second peel load to the twelfth peel load. The time intervals for measuring the first peel load to the twelfth peel load were set as equal as possible, and the final twelfth peel load was measured approximately 30 minutes after the formation of the casting film. The largest value among the first peel load to the twelfth peel load, which were the measurement results of the 12 pieces, was taken as the peel load of the casting film obtained from each dope 21. The peel loads measured for each dope 21 as described above are shown in Table 5.

[Example 17] to [Example 20]
In Examples 17 to 20, polyimide resins "PI-1" and "PI-2" were used as the polymer resin 11, and "PA-4" or "PA-6" was used as the organic compound in the amounts shown in Table 6, to produce a single-layer film by the film production equipment 20. The amount of polymer resin and organic compound relative to the solvent was 20%. The film production test was carried out on the produced film by the method described above. The film production test was carried out to measure the film thickness, peelability, peeled surface condition, and haze. In addition, a separate film was produced, and a peel load test was carried out by the method described above. The peel load was measured by the peel load test. The measurement results are shown in Table 6.

[Example 21] and [Example 22]
In Examples 21 and 22, acrylic resins "MA-1" and "MA-2" were used as the polymer resin 11, and "PA-6" was used as the organic compound in the amounts added shown in Table 6, to produce a single-layer film by film production equipment 20. The amount of polymer resin and organic compound relative to the solvent was 20%. A film production test was conducted on the produced film by the method described above. The film production test measured the film thickness, peelability, peeled surface condition, and haze. In addition, a separate film was produced, and a peel load test was conducted by the method described above. The peel load was measured by the peel load test. The measurement results are shown in Table 6.

[Comparative Example 4] and [Comparative Example 5]
In Comparative Examples 4 to 5, polyimide resins "PI-1" and "PI-2" were used as the polymer resin 11, and a single-layer film was produced by the film production equipment 20 without using any organic compound. The amount of polymer resin and organic compound relative to the solvent was 20%. The produced film was subjected to a film formation test by the method described above. The film formation test measured the film thickness, peelability, peeled surface condition, and haze. In addition, a separate film was produced, and a peel load test was performed by the method described above. The peel load was measured by the peel load test. The measurement results are shown in Table 6. In Comparative Example 5, the produced film could not be peeled off stably, so the peel load could not be measured, and "-" was entered in the columns for peeled surface condition and haze.

[Comparative Example 6] and [Comparative Example 7]
In Comparative Examples 6 to 7, acrylic resins "MA-1" and "MA-2" were used as the polymer resin 11, and single-layer films were produced by the film production equipment 20 without using any organic compound. The amount of polymer resin and organic compound relative to the solvent was 20%. A film production test was carried out on the produced films by the method described above. In the film production test, the film thickness, peelability, peeled surface condition, and haze were measured. In addition, a separate film was produced, and a peel load test was carried out by the method described above. The peel load was measured by the peel load test. The measurement results are shown in Table 6.

REFERENCE SIGNS LIST 10 film 11 polymer resin 12 organic compound 15 solvent 20 film production equipment 21 dope 22 dope preparation device 23 film production device 26

mixing tank

27, 32 pump 28 filter 31 storage tank 33 piping 36 casting die 36a discharge port 37 casting unit 38 tenter 41 roller dryer 41a roller 42 slitter 43 winder 46 band 47 roller 48 peeling roller 51 cast film 52 clip 53 blower 54 winding core PC casting position PP peeling position

Claims

a polymer resin including a plurality of main structural units not including an acid component and a plurality of acid structural units including an acid component;
an organic compound that contains a phosphate group and has acid dissociability;
A resin composition for film comprising:
The resin composition for films according to claim 1, wherein the organic compound is contained in an amount ranging from 0.01 parts by mass to 10 parts by mass relative to 100 parts by mass of the polymer resin.
The resin composition for films according to claim 1 or 2, wherein the polymer resin contains a cellulose derivative and a hemicellulose derivative.
The resin composition for films according to claim 1 or 2, wherein the polymer resin is a cellulose ester made from pulp.
The resin composition for films according to claim 1 or 2, wherein the polymer resin is a polyimide or acrylic resin.
The resin composition for films according to claim 1 or 2, wherein the acid constituent unit contains a carboxyl group.
The resin composition for films according to claim 1 or 2, wherein the acid constituent units are contained in a composition ratio ranging from 0.4% to 5% based on the entire polymer resin.
3. The resin composition for films according to claim 1, wherein the organic compound is at least one of compounds represented by the following general formula (1) or (2):

(In the above formula (1) or (2), R1 is an alkyl group having 1 to 20 carbon atoms, R2 is an alkyl group having 1 to 20 carbon atoms, R3 is an alkyl group having 1 to 6 carbon atoms, n is a natural number of 1 to 8, X is a hydroxy group, and Y and Z are each one of a hydroxy group, an alkoxy group, or oxygen.)
The resin composition for films according to claim 1 or 2, wherein the organic compound has an acid value of 100 mg (KOH)/g or more as measured according to the acid value measurement method according to JIS K0070-1992.
The resin composition for films according to claim 1 or 2, wherein the solvent is a halogenated hydrocarbon solvent.
A casting step of forming a casting film by casting a dope made of the resin composition for films according to claim 1 onto a metal support;
a peeling step of peeling the casting membrane from the support to form a film;
a drying step of drying the film;
A method for producing a film having the above structure.
In the casting step, the dope is continuously cast onto the moving support,
The method for producing a film according to claim 11 , wherein in the peeling step, the casting film is continuously peeled off from the support.
The method for producing a film according to claim 11 or 12, wherein the support is a stainless steel band.
a polymer resin including a plurality of main structural units not including an acid component and a plurality of acid structural units including an acid component;
and an organic compound which contains a phosphate group and is acid dissociable.
The film according to claim 14, wherein the organic compound is contained in a range of 0.01 parts by mass to 10 parts by mass to 100 parts by mass of the polymer resin.
The film according to claim 14 or 15, wherein the acid structural unit is contained in a composition ratio ranging from 0.4% to 5% based on the entire polymer resin.
16. The film according to claim 14, having a haze value of 2.0 or less as measured in accordance with JIS K7136.