JP5960082B2 - Film and film manufacturing method - Google Patents

Description

  The present invention relates to a film and a method for producing the film. More specifically, the present invention relates to a film containing any one of a cycloolefin resin, an acrylic resin, and an acrylic-styrene copolymer resin, and a method for producing the film.

  Conventionally, various optical films have been used for liquid crystal display devices, and optical films to which various additives are added are known. Such an optical film is manufactured by various film forming methods. As a typical method, the optical film is manufactured by a solution casting method in which a dope obtained by dissolving a polymer in a solvent is cast on a support. It is widely done.

  In recent years, it has been studied to use a polymer having a high glass transition temperature (Tg) having good heat resistance such as cycloolefin resin, acrylic resin, and acrylic-styrene copolymer resin. On the other hand, in the case where a film using a cycloolefin resin, an acrylic resin and an acrylic-styrene copolymer resin is produced by solution casting, a method for improving the peelability from the support is still fully studied. The current situation was not.

  Patent Document 1 includes a solvent (a) containing 60% by weight or more of methylene chloride and capable of dissolving a polyarylate resin, a linear or branched aliphatic alcohol having 1 to 6 carbon atoms (b), And a polyarylate-based resin solution composition comprising a polyarylate-based resin, comprising 10 parts by weight of the polyarylate-based resin with respect to 15 to 90 parts by weight of the solvent (a) and having 1 to 6 carbon atoms A polyarylate-based resin solution composition, wherein the amount of the branched or branched aliphatic alcohol (b) is 1 to 10% by weight of the total solvent system comprising the solvents (a) and (b). A method for improving the peelability from a substrate when a polyarylate film having excellent optical isotropy and homogeneity and a small amount of residual solvent is produced by casting is described.

  In Patent Document 2, a dope composed of a solid component containing a cyclic polyolefin and a solvent is caused to flow out of a casting die to form a casting film on a support, and the casting film is peeled off from the support as a film. In the manufacturing method of the cyclic polyolefin film to be dried, the drying rate of the dope immediately after being discharged from the casting die is 4 kg / min or less per 1 kg of the solid component. Describes a method for producing a cyclic polyolefin film free from streak-like defects by suppressing the occurrence of burrs in cast beads. In the example of Patent Document 2, the cycloolefin polymer was dried at 35 ° C. to 135 ° C., but the solvent was 100% toluene having a high boiling point.

In Patent Document 3, a dope composed of a solid component containing cellulose acylate and a solvent is discharged from a casting die to form a casting film on a support, and the casting film is peeled off from the support. In the solution casting method, the drying rate of the dope immediately after being discharged from the casting die is 4 kg / min or less per kg of the solid component, and the cellulose acylate has the following formulas (I) and (II): According to the solution casting method characterized by satisfying the above, there is described a method for producing a film that is superior in moisture and heat resistance and more easily oriented than the TAC film so as not to cause quality defects in the casting process (however, In the formulas (I) and (II), A represents the degree of substitution of the acetyl group with respect to the hydrogen atom of the hydroxyl group of cellulose, B represents the propionyl group with respect to the hydrogen atom of the hydroxyl group of cellulose, butyryl This represents the sum of the substitution degrees of the ru group, pentanoyl group, and hexanoyl group.)
(I) 2.5 ≦ A + B ≦ 3.0
(II) 1.25 ≦ B ≦ 3.0
In Examples of Patent Document 3, methylene chloride / methanol is used as a solvent and the drying temperature is 35 ° C. to 135 ° C., but cellulose acetate propionate (CAP) or cellulose acetate butyrate (CAB) is used as a polymer. .

JP-A-8-302162 JP 2007-245687 A JP 2006-188052 A

When the inventors manufactured a film using a polymer having a high glass transition temperature (Tg) having good heat resistance such as cycloolefin resin, acrylic resin and acrylic-styrene copolymer resin, by solution casting, When casting by adding a poor solvent such as alcohol with reference to Patent Document 1 in order to improve the stripping property in solution casting of a high glass transition temperature (Tg) polymer having good heat resistance, the good solvent having a low boiling point is It was found that the poor solvent having a high boiling point was left as bubbles and the film was whitened accordingly.
When the present inventors examined the method described in Patent Document 2, the cycloolefin polymer obtained in each Example of Patent Document 2 has a Tg of about 78 ° C., and a resin having a higher Tg can be used. It was unknown.
When the present inventors examined the method of patent document 3, since polymers, such as CAP and CAB used in the Example of patent document 3, have high affinity with methanol, methanol does not precipitate by drying. In the first place, whitening does not occur, and it cannot be applied to cycloolefin resins, acrylic resins, acrylic-styrene copolymer resins, and the like.

  That is, the problem to be solved by the present invention is to simultaneously achieve whitening suppression of the entire film after casting, suppression of bubble generation and improvement of peelability from the support when a film having excellent heat resistance is formed into a solution. It is in providing the manufacturing method of the film which can be performed.

In order to solve the above-mentioned problems, the present inventors diligently studied, and when forming a solution, a specific alcohol was further used as a solvent in a specific quantitative ratio for improving the peelability, and a specific residual solvent was used. Tg-70 based on the glass transition temperature (Tg) when the polymer used is made into a film at 40 ° C. or higher which is the boiling point of methylene chloride used in Patent Document 1 with respect to the amount of the doped film. By increasing the drying start temperature to a temperature of ℃ or higher, the film having a temperature higher than the WetTg described later becomes fluid, and whitening is suppressed by eliminating and filling the bubbles, and at the same time, the peelability is improved by alcohol. As a result of obtaining the effect, it was also possible to suppress the whitening of the entire film after casting, to suppress the generation of bubbles and to improve the peelability from the support when a film having excellent heat resistance was formed into a solution. It found that can be achieved, which resulted in the completion of the present invention.
Specific means for solving the above-described problems are as follows.

[1] A step of casting a dope containing any one of a cycloolefin resin, an acrylic resin and an acrylic-styrene copolymer resin and a solvent on a support,
A first drying step of forming a dope film in which the dope after casting is maintained at an atmospheric temperature of less than 40 ° C. and a residual solvent amount is controlled to 35 to 65% by mass;
When the amount of residual solvent in the dope film after the first drying step is 35 to 65% by mass (however, the amount of residual solvent after the first drying step is not exceeded) A second drying step of drying at an ambient temperature exceeding Tg-70 ° C;
Including a step of peeling the dope film after the second drying step from the support to form a film,
1 to 13% by mass of the solvent is an alcohol having an average carbon number of 1 to 4,
A method for producing a film, wherein the Tg of the film is 90 ° C. or more (where Tg represents a glass transition temperature (unit: ° C.) of the film after drying).
[2] In the method for producing a film according to [1], the drying start temperature in the second drying step is preferably 40 ° C. or higher, Tg−50 ° C. or higher, and Tg−10 ° C. or lower (however, Tg Represents the glass transition temperature (unit: ° C.) of the film after drying.
[3] In the method for producing a film according to [1] or [2], the Tg of the film is preferably 100 to 290 ° C. (where Tg is the glass transition temperature (unit: ° C.) of the film after drying). Represents).
[4] In the method for producing a film according to any one of [1] to [3], 4 to 10% by mass of the solvent is preferably an alcohol having an average carbon number of 1 to 4.
[5] In the method for producing a film according to any one of [1] to [4], the alcohol contained in the solvent is preferably an alcohol having an average carbon number of 1 to 2.
[6] In the method for producing a film according to any one of [1] to [5], the film thickness is preferably 20 to 60 μm.
[7] In the method for producing a film according to any one of [1] to [6], the amount of residual solvent immediately before the second drying step is preferably 50 to 65% by mass.
[8] In the method for producing a film according to any one of [1] to [6], 1% by mass or more of the dope is preferably a moisture permeability reducing compound.
[9] A film produced by the method for producing a film according to any one of [1] to [8].

  According to the present invention, when a film having excellent heat resistance is formed into a solution, production of a film that can simultaneously achieve suppression of whitening of the entire film after casting, suppression of bubble generation, and improvement of peelability from the support. A method can be provided.

  Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

[Film Production Method]
The film production method of the present invention (hereinafter also referred to as the production method of the present invention) comprises a dope containing any one of a cycloolefin resin, an acrylic resin and an acrylic-styrene copolymer resin and a solvent on a support. And a first drying step of forming a dope film in which the amount of residual solvent is controlled to 35 to 65% by mass while maintaining the dope after casting at an atmospheric temperature of less than 40 ° C., and When the amount of residual solvent in the dope film after the first drying step is 35 to 65% by mass (however, it does not exceed the amount of residual solvent after the first drying step), the drying start temperature 40 A second drying step of drying at an ambient temperature of at least C ° C. and exceeding Tg−70 ° C., and a step of peeling the dope film after the second drying step from the support to form a film, 1-13 quality % Is an alcohol with an average 1 to 4 carbon atoms, Tg of the film is characterized in that at 90 ° C. or higher (where, Tg is the glass transition temperature of the film after drying (unit: represents a ° C.)).
By the film manufacturing method having such a configuration, simultaneously suppressing whitening of the entire film after casting, suppression of bubble generation, and improvement of peelability from the support when a film having excellent heat resistance is formed into a solution. Can do.
Here, in the drying step before peeling described in Patent Document 1, after drying to a certain extent below the boiling point of methylene chloride at 35 ° C., second drying at 45 to 75 ° C. is performed, and the polymer is a good solvent. This was a method in which a certain methylene chloride (boiling point: 40 ° C.) was evaporated before methanol (boiling point: 65 ° C.) as a poor solvent. As a result, the ratio of methanol in the dope film is increased, and it is estimated that the poor solvent that cannot be dissolved is deposited in the dope film. When the drying progresses as it is and the poor solvent evaporates, the space where the poor solvent was present remains as a cavity of about 3 to 5 μm, and the entire film appears whitened.
On the other hand, whitening and bubble generation can be eliminated by raising the drying temperature to the range of the present invention. Without being bound by any theory, it is considered that when the dope film is in a wet state by a solvent, Tg is lower than the dry state (hereinafter, the Tg containing the solvent is referred to as WetTg). . As the residual solvent amount increases, the WetTg decreases, and the WetTg increases as the dope film is dried. When the drying temperature is started from WetTg or lower, the film is gradually dried while maintaining its shape, so that the film remains with bubbles remaining. In contrast, in the present invention, by applying a temperature of 40 ° C. or higher and a polymer Wet Tg or higher, the methanol ratio in the dope film increases, and even if the poor solvent that cannot be completely dissolved is precipitated in the dope film, Since the dope film flows and fills the bubbles when the solvent evaporates, it is estimated that whitening is eliminated.
Hereinafter, the production method of the present invention will be described.

  The film of the present invention is produced by a solution casting method (solvent casting method). Examples of the production of cellulose acetate films using the solvent cast method are described in US Pat. Nos. 2,336,310, 2,367,603, 2,492,078, 2,492,977, 2,492,978, 2,607,704, 2,739,069 and 2,739,070, British Patent Nos. 640731 and 736892, and Japanese Patent Publication Nos. 45-4554, 49-5614, JP-A-60-176834, JP-A-60-203430 and JP-A-62-115035 can be referred to. In addition, the film of the present invention is preferably subjected to a stretching treatment. Regarding stretching methods and conditions other than those specified in the present specification, for example, JP-A-62-115035, Publications such as 4-152125, 4-284221, 4-298310, and 11-48271 can be referred to.

<Preparation of dope>
In the solvent cast method, a film can be produced using a dope (solution) containing any one of a cycloolefin resin, an acrylic resin, and an acrylic-styrene copolymer resin and a solvent.

In the solvent casting method, the dope used in the production method of the present invention is characterized in that it contains any one of a cycloolefin resin, an acrylic resin and an acrylic-styrene copolymer resin, and a solvent. By using such a dope, a film having high heat resistance can be obtained.
Hereinafter, the dope used for the film of this invention and each component contained in dope are demonstrated.

(Cycloolefin resin)
There is no restriction | limiting in particular as said cycloolefin resin, A well-known cycloolefin resin can be used.

[Compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule]
A compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule functions as a binder. In addition, a compound having a cycloaliphatic hydrocarbon group and an unsaturated double bond group can function as a curing agent, and can improve the strength and scratch resistance of the coating film, while at the same time being low. Moisture permeability can be imparted.
By using such a compound, low moisture permeability and high film strength can be realized. Although the details are not clear, by using a compound having a cycloaliphatic hydrocarbon group in the molecule, a hydrophobic cycloaliphatic hydrocarbon group is introduced into the low moisture-permeable layer, and is hydrophobized. Prevents uptake of molecules and reduces moisture permeability. Moreover, by having an unsaturated double bond group in a molecule | numerator, a crosslinking point density is raised and the diffusion path | route of the water molecule in a low moisture-permeable layer is restrict | limited. Increasing the crosslink point density also has the effect of relatively increasing the density of the cyclic aliphatic hydrocarbon group, making the inside of the low moisture permeable layer more hydrophobic, preventing the adsorption of water molecules, and reducing the moisture permeability. it is conceivable that.
In order to increase the crosslinking point density, the number of unsaturated double bond groups in the molecule is more preferably 2 or more.

The cyclic aliphatic hydrocarbon group is preferably a group derived from an alicyclic compound having 7 or more carbon atoms, more preferably a group derived from an alicyclic compound having 10 or more carbon atoms, and further preferably Is a group derived from an alicyclic compound having 12 or more carbon atoms.
The cycloaliphatic hydrocarbon group is particularly preferably a group derived from a polycyclic compound such as bicyclic or tricyclic.
More preferably, the central skeleton of the compound described in the claims of JP-A No. 2006-215096, the central skeleton of the compound described in JP-A No. 2001-10999, or the skeleton of an adamantane derivative may be mentioned.

  As the cyclic aliphatic hydrocarbon group (including a linking group), a group represented by any one of the following general formulas (I) to (V) is preferable, and the following general formula (I), (II), or (IV) Is more preferable, and a group represented by the following general formula (I) is more preferable.

  In general formula (I), L and L 'each independently represent a divalent or higher linking group and are not divalent simultaneously. n represents an integer of 1 to 3.

  In general formula (II), L and L ′ each independently represent a divalent or higher linking group, and are not divalent simultaneously. n represents an integer of 1 to 2.

  In general formula (III), L and L ′ each independently represent a divalent or higher linking group and are not divalent simultaneously. n represents an integer of 1 to 2.

  In general formula (IV), L and L ′ each independently represent a divalent or higher valent linking group, and L ″ represents a hydrogen atom or a divalent or higher valent linking group.

  In general formula (V), L and L ′ each independently represent a divalent or higher valent linking group and are not divalent simultaneously.

  Specific examples of the cyclic aliphatic hydrocarbon group include norbornyl, tricyclodecanyl, tetracyclododecanyl, pentacyclopentadecanyl, adamantyl, diamantanyl and the like.

Examples of the unsaturated double bond group include polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group and —C (O) OCH═CH ₂ Is preferred. Particularly preferably, a compound containing three or more (meth) acryloyl groups in one molecule described below can be used.

A compound having a cycloaliphatic hydrocarbon group and having 3 or more unsaturated double bond groups in the molecule has the above-described cycloaliphatic hydrocarbon group and the group having an unsaturated double bond as a linking group. It is comprised by connecting via.
As the linking group, a single bond, an alkylene group having 1 to 6 carbon atoms which may be substituted, an amide group which may be substituted at the N-position, a carbamoyl group which may be substituted at the N-position, or an ester group , An oxycarbonyl group, an ether group, and the like, and groups obtained by combining these.

These compounds include, for example, polyols such as diols and triols having the above cyclic aliphatic hydrocarbon groups, and carboxylic acids and carboxylic acid derivatives of compounds having (meth) acryloyl groups, vinyl groups, styryl groups, allyl groups, etc. It can be easily synthesized by a one-step or two-step reaction with an epoxy derivative, an isocyanate derivative or the like.
Preferably, compounds such as (meth) acrylic acid, (meth) acryloyl chloride, (meth) acrylic anhydride, glycidyl (meth) acrylate, and compounds described in WO2012 / 00316A (eg, 1,1-bis ( (Acryloxymethyl) ethyl isocyanate) can be synthesized by reacting with a polyol having the above cyclic aliphatic hydrocarbon group.

  Preferred specific examples of the compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group are shown below, but the present invention is not limited thereto.

[Other cycloolefin polymers]
Examples of other cycloolefin polymers that can be used in the present invention include (1) norbornene-based polymers, (2) monocyclic olefin polymers, (3) cyclic conjugated diene polymers, (4) There are vinyl alicyclic hydrocarbon polymers and hydrides of (1) to (4).
The cycloolefin polymer preferred for the present invention is an addition (co) polymer cyclic polyolefin resin containing at least one repeating unit represented by the following general formula (102) and, if necessary, the general formula (101). It is an addition (co) polymer cyclic polyolefin resin further comprising at least one repeating unit. A ring-opening (co) polymer containing at least one cyclic repeating unit represented by the general formula (103) can also be suitably used.

In formulas (101) to (103), m represents an integer of 0 to 4. R ^{1 to} R ⁶ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, X ^{1 to} X ³ and Y ^{1 to} Y ³ are a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, and a halogen atom. substituted hydrocarbon group having 1 to 10 carbon _{atoms, - (CH 2) n COOR} 11, - (CH 2) n OCOR 12, - (CH 2) n NCO, - (CH 2) n NO 2, - ( _{CH 2) n CN, - (} CH 2) n CONR 13 R 14, - (CH 2) n NR 13 R 14, - (CH 2) n OZ, - (CH 2) n W, or X ¹ and Y ¹ Alternatively, (—CO) ₂ O and (—CO) ₂ NR ¹⁵ composed of X ² and Y ² or X ³ and Y ³ are shown. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ are hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, Z is a hydrocarbon group or a hydrocarbon group substituted with a halogen, and W is SiR ¹⁶ _p. D _3-p (R ¹⁶ is a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁶ or —OR ¹⁶ , p is an integer of 0 to 3), n is an integer of 0 to 10 Show.

Norbornene polymer hydrides are disclosed in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19807, JP-A-2003-115767, or JP-A-2004-309799. As disclosed in No. 1, etc., a polycyclic unsaturated compound is produced by addition polymerization or metathesis ring-opening polymerization and then hydrogenation. In the norbornene-based polymer used in the present invention, R ^{5 to} R ⁶ are preferably a hydrogen atom or —CH ₃ , X ³ and Y ³ are preferably a hydrogen atom, Cl, —COOCH ₃ , and other groups are appropriately selected. The This norbornene-based resin is sold under the trade name of Arton G (for example, ARTON G7810) or Arton F by JSR Co., Ltd., and ZEONOR ZF14, ZF16, These are commercially available under the trade names of Zeonex 250 or Zeonex 280, and these can be used.

  Norbornene-based addition (co) polymers are disclosed in JP-A No. 10-7732, JP-T-2002-504184, U.S. Published Patent No. 200429129157A1 or WO2004 / 070463A1. It can be obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and ethylene, propylene, butene; conjugated dienes such as butadiene and isoprene; nonconjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride It is also possible to carry out addition polymerization with linear diene compounds such as acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate and vinyl chloride. This norbornene-based addition (co) polymer is marketed by Mitsui Chemicals, Inc. under the name of Apel, and has different glass transition temperatures (Tg) such as APL8008T (Tg70 ° C), APL6013T (Tg125 ° C) or APL6015T ( Grades such as Tg145 ° C). Pellets such as TOPAS 8007, 6013, and 6015 are sold by Polyplastics Co., Ltd. Further, Appear 3000 is sold by Ferrania.

  In the present invention, the glass transition temperature (Tg) of the cyclic polyolefin-based resin is not limited, but a high-Tg cyclic polyolefin resin such as 200 to 400 ° C. can also be used.

  The weight average molecular weight of the cycloolefin resin is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, and still more preferably 10,000 to 500,000. And particularly preferably within the range of 50,000 to 500,000.

  A commercially available cycloolefin resin may be used. Moreover, you may obtain by synthesis | combination, for example, a cycloolefin resin can be synthesize | combined with reference to Unexamined-Japanese-Patent No. 2009-42882 and Unexamined-Japanese-Patent No. 2009-138129.

(acrylic resin)
The repeating structural unit of the (meth) acrylic acid resin is not particularly limited. The (meth) acrylic resin preferably has a repeating structural unit derived from a (meth) acrylic acid ester monomer as a repeating structural unit.

  The (meth) acrylic resin is a concept including both a methacrylic resin and an acrylic resin. The (meth) acrylic resin also includes acrylate / methacrylate derivatives, particularly acrylate / methacrylate (co) polymers.

The (meth) acrylic acid ester is not particularly limited, and examples thereof include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and benzyl acrylate. Acrylic acid esters; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, methacrylic acid esters such as benzyl methacrylate; These may be used alone or in combination of two or more. Among these, methyl methacrylate is particularly preferable from the viewpoint of excellent heat resistance and transparency.
When the (meth) acrylic acid ester is used, the content ratio in the monomer component to be subjected to the polymerization step is preferably 10 to 100% by weight, more preferably 10%, in order to sufficiently exhibit the effects of the present invention. -100% by weight, more preferably 40-100% by weight, particularly preferably 50-100% by weight.

  The weight average molecular weight of the acrylic resin is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, still more preferably 10,000 to 500,000. Within the range, particularly preferably within the range of 50,000 to 500,000.

  A commercially available product may be used as the acrylic resin. Moreover, you may obtain by a synthesis | combination, for example, it can synthesize | combine an acrylic resin with reference to Unexamined-Japanese-Patent No. 2011-202012.

(Acrylic-styrene copolymer resin)
The acrylic-styrene copolymer resin is constructed by polymerizing at least one selected from a repeating unit derived from (meth) acrylic acid and a monomer represented by the following general formula (201) as a repeating structural unit. And repeating structural units derived from styrene.

General formula (201)
CH ₂ = C (X) R ²⁰¹

(In the formula, R ²⁰¹ represents a hydrogen atom or a methyl group, and X represents a substituted or unsubstituted phenyl.)

  Examples of the monomer represented by the general formula (201) include styrene, methylstyrene, and hydroxystyrene. These may be used alone or in combination of two or more. . Among these, styrene is particularly preferable in that the effects of the present invention are sufficiently exhibited.

  As a repeating unit derived from (meth) acrylic acid that can be used for the acrylic-styrene copolymer resin, (meth) acrylic acid ester is preferable, and methyl methacrylate (methyl methacrylate) is more preferable.

  The weight average molecular weight of the acrylic-styrene copolymer resin is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, and still more preferably 10,000. It is in the range of ˜500,000, particularly preferably in the range of 50,000 to 500,000.

  As the acrylic-styrene copolymer resin, a commercially available one may be used, and Nippon Steel & Sumikin Chemical Co., Ltd. Estyrene MS-600 may be used.

  When the monomer represented by the general formula (201) is used, the content ratio in the monomer component to be subjected to the polymerization step is preferably 1 to 80 mass in order to sufficiently exhibit the effects of the present invention. %, More preferably 1 to 60% by mass, particularly preferably 1 to 40% by mass.

The monomer component may form a lactone ring after polymerization. In that case, it is preferable to polymerize the monomer component to obtain a polymer having a hydroxyl group and an ester group in the molecular chain.
As a polymerization reaction form for polymerizing the monomer component to obtain a polymer having a hydroxyl group and an ester group in the molecular chain, a polymerization form using a solvent is preferable, and solution polymerization is particularly preferable. .
For example, a lactone ring structure described in JP 2007-316366 A, JP 2005-189623 A, WO 2007/032304, WO 2006/025445 is also preferable. It is.

In the case of a polymerization form using a solvent, the polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ether solvents such as tetrahydrofuran Etc., and only one of these may be used, or two or more may be used in combination.
Further, in the production method of the present invention, since the (meth) acrylic resin is dissolved in an organic solvent and formed by solution casting, the organic solvent at the time of synthesizing the (meth) acrylic resin is a melt film formation. It is not limited as compared with the case where it is performed, and it may be synthesized using an organic solvent having a high boiling point.

During the polymerization reaction, a polymerization initiator may be added as necessary. Although it does not specifically limit as a polymerization initiator, For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amyl Organic peroxides such as peroxy-2-ethylhexanoate; 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2, Azo compounds such as 4-dimethylvaleronitrile), and the like. These may be used alone or in combination of two or more. The amount of the polymerization initiator used is not particularly limited as long as it is appropriately set according to the combination of the monomers used and the reaction conditions.
The weight average molecular weight of the polymer can be adjusted by adjusting the amount of the polymerization initiator.

  When performing the polymerization, it is preferable to control the concentration of the produced polymer in the polymerization reaction mixture to be 50% by weight or less in order to suppress gelation of the reaction solution. Specifically, when the concentration of the produced polymer in the polymerization reaction mixture exceeds 50% by weight, it is preferable that the polymerization solvent is appropriately added to the polymerization reaction mixture and controlled to be 50% by weight or less. . The concentration of the produced polymer in the polymerization reaction mixture is more preferably 45% by weight or less, still more preferably 40% by weight or less.

  The form in which the polymerization solvent is appropriately added to the polymerization reaction mixture is not particularly limited, and the polymerization solvent may be added continuously or intermittently. By controlling the concentration of the produced polymer in the polymerization reaction mixture in this way, the gelation of the reaction solution can be more sufficiently suppressed. The polymerization solvent to be added may be the same type of solvent used during the initial charging of the polymerization reaction or may be a different type of solvent, but is the same as the solvent used during the initial charging of the polymerization reaction. It is preferable to use different types of solvents. Further, the polymerization solvent to be added may be only one type of solvent or a mixed solvent of two or more types.

  In the dope used in the present invention, the amount of cycloolefin resin, acrylic resin and acrylic-styrene copolymer resin is preferably adjusted so that it is contained in an amount of 10 to 40% by mass in the resulting dope. The amount of cellulose acetate is more preferably 10 to 30% by mass.

(solvent)
In the solvent used in the present invention, 1 to 13% by mass of the solvent is an alcohol having an average carbon number of 1 to 4.
The solvent preferably further contains a halogenated hydrocarbon, more preferably methylene chloride. As the solvent, in addition to methylene chloride, other halogenated hydrocarbons may be used. The number of carbon atoms in these methylene chloride or other halogenated hydrocarbons is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Examples of the halogenated hydrocarbon include methylene chloride, chloroform, methyl chloride, carbon tetrachloride, trichloroacetic acid, methyl bromide, methyl uride, tri (tetra) chloroethylene and the like.

In the present invention, the solvent further includes an alcohol which is a poor solvent, and 1 to 13% by mass of the solvent is an alcohol having an average carbon number of 1 to 4.
Furthermore, it is preferable that the boiling point of a poor solvent is 120 degrees C or less, and it is more preferable that it is 40-100 degreeC. By setting the boiling point to 120 ° C. or less, the drying rate of the solvent can be further increased, which is preferable.

Preferred examples of such alcohols having an average carbon number of 1 to 4 include alcohols (methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, and n-hexanol). Among them, in the production method of the present invention, it is more preferable to use a primary alcohol (methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol), and methanol is most preferable from the viewpoint of peelability. preferable.
Moreover, as long as the alcohol average carbon number contained in dope is 1-4, you may mix and use the said alcohol 2 or more types. Furthermore, as long as the average carbon number is 1 to 4, naturally an alcohol having 5 or more carbon atoms may be used. Specifically, a solvent in which ethanol, which is an alcohol having 2 carbon atoms, methanol having 1 carbon atom, and ethanol / methanol = 1/1 (mass ratio) or more can be used.
The average carbon number of the alcohol contained as a solvent in the dope is 1 to 4, more preferably 1 to 2.5, and particularly preferably 1 to 2.
The content of the alcohol having 1 to 4 average carbon atoms contained as a solvent in the dope is 1 to 13% by mass, preferably 4 to 10% by mass, and 6 to 8% by mass. % Is particularly preferred. When the content of the alcohol having an average carbon number of 1 to 4 contained as a solvent in the dope is 1% by mass or more, the releasability can be improved, and when the content is 4% or more, the releasability can be further improved. If it is 6% by mass or more, the peelability can be further improved. Bubble generation and whitening can be suppressed when the content of the alcohol having an average carbon number of 1 to 4 contained as a solvent in the dope is 13% by mass or less, and generation of bubbles due to alcohol when the content is 8% by mass or less. And whitening can be suppressed.

(Additive)
In the film of the present invention, as additives, moisture permeability reducing compounds; peeling accelerators; Rth control agents (including non-phosphate ester compounds); inorganic fine particles (matting agents); phthalates and phosphates Additives such as plasticizers such as series compounds; Re developing agents; ultraviolet absorbers; antioxidants can also be added. As the peeling accelerator, Rth control agent, inorganic fine particles, plasticizer, and Re developing agent, those described in JP-A No. 2011-183854 can be used.

In the film manufacturing method of the present invention, it is preferable to use a moisture permeability reducing compound for the dope. During the dope, the moisture permeability reducing compound is preferably added in an amount of 1% by mass or more based on the cycloolefin resin, the acrylic resin, or the acrylic-styrene copolymer resin. Although there is no particular upper limit on performance, from the viewpoint of film production, the moisture permeability reducing compound is preferably 150% by mass or less based on the cycloolefin resin, the acrylic resin or the acrylic-styrene copolymer resin. .
The moisture permeability reducing compound may have a structure including one or more aromatic rings. Hydrophobic properties can be imparted to the film by the aromatic ring, and moisture permeation and desorption can be suppressed.
More preferably, the moisture permeability reducing compound has a structure containing three or more aromatic rings.
The moisture permeability reducing compound preferably contains one or more —OH groups, more preferably contains three or more aromatic rings, and more preferably contains one or more —OH groups.

  Furthermore, among these respective moisture permeation reducing compounds, a structure containing one or more aromatic rings is preferable, and a structure containing three or more aromatic rings is more preferable.

As the moisture permeability reducing compound contained in the optical film of the present invention, a compound represented by the following general formula (B) can be preferably used.
General formula (B)

In the general formula ^{(B), R 12, R} 13, R 14, R 15, R 16, R 21, R 23, R 24, R 25, R 32, R 33, R 34, R 35, R 36 are, Each represents a hydrogen atom or a substituent, and the substituent T described below can be applied as the substituent. Moreover, the general formula in ^{(B) R 12, R 13} , R 14, R 15, R 16, R 21, R 23, R 24, R 25, R 32, R 33, R 34, R 35 and R ³⁶ At least one of them is an amino group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a hydroxy group, a mercapto group, or a carboxyl group.

Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an isopropyl group, and tert-butyl. Group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 carbon atoms). To 12, particularly preferably 2 to 8 carbon atoms, such as vinyl group, allyl group, 2-butenyl group, and 3-pentenyl group), alkynyl group (preferably 2 to 20 carbon atoms, more preferably Has 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include a propargyl group and a 3-pentynyl group.), Aryl (Preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include a phenyl group, a p-methylphenyl group, and a naphthyl group.), An amino group (Preferably has 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, and particularly preferably 0 to 6 carbon atoms. For example, amino group, methylamino group, dimethylamino group, diethylamino group, dibenzylamino group, etc. And an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group. ), An aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl A xy group, a 2-naphthyloxy group, etc.), an acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, such as an acetyl group, A benzoyl group, a formyl group, a pivaloyl group, etc.), an alkoxycarbonyl group (preferably having a carbon number of 2 to 20, more preferably a carbon number of 2 to 16, particularly preferably a carbon number of 2 to 12, such as methoxycarbonyl Group, an ethoxycarbonyl group, etc.), an aryloxycarbonyl group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, particularly preferably having 7 to 10 carbon atoms, such as a phenyloxycarbonyl group. An acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, especially Preferably it is C2-C10, for example, an acetoxy group, a benzoyloxy group, etc. are mentioned. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include an acetylamino group and a benzoylamino group), alkoxycarbonyl. An amino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group), an aryloxycarbonylamino group (preferably Has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group, and a sulfonylamino group (preferably 1 to 1 carbon atom). 20, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. Nylamino group, benzenesulfonylamino group, etc.), sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl group, methyl A sulfamoyl group, a dimethylsulfamoyl group, a phenylsulfamoyl group, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to carbon atoms). 12 and examples thereof include a carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably carbon atoms). Examples thereof include methylthio group and ethylthio group. ), An arylthio group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as a phenylthio group), a sulfonyl group (preferably C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12, For example, a mesyl group, a tosyl group, etc. are mentioned), a sulfinyl group (preferably C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, a methanesulfinyl group, a benzenesulfinyl group, etc.), a ureido group (preferably C1-C20, more preferably carbon) The number is 1 to 16, particularly preferably 1 to 12, and examples thereof include a ureido group, a methylureido group, and a phenylureido group. ), A phosphoric acid amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, such as a diethylphosphoric acid amide group and a phenylphosphoric acid amide group. Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group Group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, specifically an imidazolyl group, a pyridyl group, a quinolyl group Group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, etc. ), A silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group. For example). Among these, an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, and an aryloxy group are more preferable, and an alkyl group, an aryl group, and an alkoxy group are more preferable.
These substituents may be further substituted with a substituent T. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

Further, in the general formula ^{(B), R 12, R} 13, R 14, R 15, R 16, R 21, R 23, R 24, R 25, R 32, R 33, R 34, R 35, R 36 At least one of them is an amino group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a hydroxy group, a mercapto group, or a carboxyl group, more preferably an amino group or a hydroxy group. A hydroxy group is preferred. These groups may be substituted with a substituent. As the substituent in this case, the above-described substituent T can be applied, and the preferred range is also the same.

  Preferred examples of the compound represented by formula (B) of the present invention are shown below, but the present invention is not limited to these specific examples.

  Examples of the moisture permeability reducing compound include petroleum resins, terpene resins, terpene phenol resins, rosin resins, coumarone resins, resins using formaldehyde as raw materials (phenolic resins such as phenolformaldehyde resins and derivatives thereof, aromatic hydrocarbon formaldehyde resins and Derivatives thereof), and hydrides thereof can also be preferably used.

As the phenolic resin, a novolak type phenolic resin is preferable.
The novolac type phenol resin is a normal novolac type phenol resin obtained by reacting phenol and formaldehyde (formalin) under an acidic catalyst such as oxalic acid. There is no restriction | limiting in particular as a raw material of this phenol, For example, phenol, o-cresol, m-cresol, p-cresol, p-tert-butylphenol, p-tert-octylphenol, p-octylphenol, p-nonylphenol etc. and those Mixtures can be used. As a raw material of the phenol, p-cresol is preferable.
Moreover, as a raw material of formaldehyde, formalin, paraform, acetal, etc., and mixtures thereof can be used.

As the aromatic hydrocarbon formaldehyde resin, a general aromatic hydrocarbon formaldehyde resin generally obtained by reacting an aromatic hydrocarbon and formaldehyde (formalin) can be used. There is no restriction | limiting in particular as a raw material of this aromatic hydrocarbon, For example, the triisomer of toluene, xylene, a mesitylene, a C10 or more monocyclic aromatic hydrocarbon compound, etc., and mixtures thereof can be used. Among the aromatic hydrocarbons, xylene is preferable, and m-xylene is more preferable.
Moreover, as a raw material of formaldehyde, formalin, paraform, acetal, etc., and mixtures thereof can be used.

  The terpene resin is preferably a hydrogenated terpene resin.

  Barbituric acids can also be used as the moisture permeability reducing compound.

(Manufacture of dope)
In the production method of the present invention, the dope can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (room temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a normal solvent cast method. The dope can be prepared by stirring one of the cycloolefin resin, the acrylic resin, and the acrylic-styrene copolymer resin and the solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, cycloolefin resin, acrylic resin, acrylic-styrene copolymer resin and solvent are placed in a pressure vessel and sealed, and the temperature is within the range above the boiling point of the solvent at normal temperature and under which the solvent does not boil under pressure. Stir while heating. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

  Each component may be roughly mixed in advance and then placed in a container (tank or the like). Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.

When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. It is preferable to dissolve each component in a solvent in the container. The prepared dope is preferably taken out of the container after cooling, or after taking out, it is preferably cooled using a heat exchanger or the like.

  The solid content concentration contained in the dope is preferably controlled to 15% to 25% from the viewpoint of the film surface after drying, more preferably 16% to 23%, and more preferably 17% to 22%. It is particularly preferred to control.

<Film forming process>
The production method of the present invention includes a step of casting a dope containing any one of a cycloolefin resin, an acrylic resin and an acrylic-styrene copolymer resin and a solvent on a support.
Hereinafter, a preferable aspect is demonstrated about the said film forming process in the manufacturing method of this invention.

The equipment used in the film-forming step in the method for producing a film using a cycloolefin resin, an acrylic resin, and an acrylic-styrene copolymer resin is the same as the solution casting film-forming method conventionally used for cellulose triacetate film production, and A solution casting film forming apparatus is used. In the production method of the present invention, for example, a production apparatus described in JP-A No. 2004-359379 can be preferably used.
As for casting in the solvent casting method and the drying method described later, U.S. Pat. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-115035.
Further, JP-A Nos. 2000-301555, 2000-301558, 7-032391, JP-A 3-193316, JP-A-5-086212, JP-A-62-237113, JP-A-2-276607. The cellulose acylate film forming techniques described in JP-A-55-014201, JP-A-2-111511, and JP-A-2-208650 can be applied in the present invention.
Hereinafter, more specifically, a preferable aspect is demonstrated about the said film forming process.

  In the casting process, a method of extruding from a die, a method using a doctor blade, a method using a reverse roll coater, or the like is used. Industrially, the most common method is to continuously extrude a dope from a die onto a belt-like or drum-like support substrate. Examples of the support substrate used include a glass substrate, a metal substrate such as stainless steel and ferrotype, and a plastic substrate such as polyethylene terephthalate. Needless to say, the material and surface state of the support substrate also have a great influence on the peelability of the cast film. For example, in a substrate coated with Teflon (registered trademark) or the like having a very low surface tension, the peelability is good. However, in order to industrially continuously form a film having a high surface property and optical homogeneity, a glass substrate or a metal substrate having a mirror-finished surface is most commonly used. The effect is recognized even with a glass substrate or a metal substrate.

There is no restriction | limiting in particular as said metal substrate, A well-known moving strip | belt-shaped support body etc. can be mentioned.
The moving belt-like support is not particularly limited, but is preferably in the form of a band or a belt, and more preferably an endless band or belt. By using such an endless support, the dope can be moved endlessly. Further, the belt-like support may be moved in any manner, but is particularly preferably an endless belt that is stretched between two or more rolls (drums).
Moreover, there is no restriction | limiting in particular about the material of the said strip | belt-shaped support body, However, It is preferable that it is metal, and it is more preferable that it is the product made from SUS (for example, SUS316).
The specific heat of the belt-like support is preferably 0.1 to 1.0 J / (m ³ · K).
The width of the belt-like support is preferably 1 to 3 m, more preferably 1.5 to 3 m, and particularly preferably about 2 m. In addition, about 2 m here means a range of 2 m ± 30 cm.
The length of the belt-like support (so-called band length) is preferably 80 to 100 m.
The surface roughness (Ra value) of the belt-like support is preferably 0.01 μm or less. The surface of the belt-like support is preferably finished in a mirror state. The mirror finish means that the surface of the band is smoothed by repeating polishing. Furthermore, it is more preferable that the surface of the band is finished to a so-called super mirror surface having higher thickness accuracy in the width direction.
The thickness of the belt-like support is preferably 1.5 to 2 mm.

  The dope temperature at the time of casting is 10 to 40 ° C., preferably 15 to 35 ° C. In order to obtain a film having excellent smoothness, it is necessary to cast and smooth the solution extruded from the die on the support. At this time, if the casting temperature is too high, the surface is dried and solidified before being smoothed, which is not preferable. On the other hand, if the temperature is too low, the casting solution is cooled to increase the viscosity, and it is difficult to obtain smoothness and condensation is not preferable.

  Before shifting from the casting process to the drying process, the surface property of the film can be highly smoothed (leveling effect) by suppressing the drying for a certain period of time and ensuring the fluidity of the dope.

<First drying step, second drying step>
The production method of the present invention includes a first drying step of forming a dope film in which the dope after casting is maintained at an atmospheric temperature of less than 40 ° C. and the residual solvent amount is controlled to 35 to 65% by mass; When the dope film after the drying step has a residual solvent amount of 35 to 65% by mass (however, it does not exceed the residual solvent amount after the first drying step), the drying start temperature is 40 ° C. or higher and Tg-70 Including a second drying step of drying at an ambient temperature exceeding ° C. By such a 1st drying process and a 2nd drying process, suppression of whitening of a film and suppression of bubble generation can be achieved simultaneously.

The residual solvent amount can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the web of which M is measured is dried at 110 ° C. for 3 hours.

In the pre-peeling drying step such as the first drying step and the second drying step, it is necessary to evaporate and remove most of the solvent from the dope cast on the support in as short a time as possible. However, the drying conditions should be carefully selected because they undergo deformation due to foaming when rapid evaporation occurs.
In the first drying step, drying is carried out from the range where the boiling point of the lowest solvent (preferably methylene chloride) among the solvents to be used, preferably the boiling point of the solvent (preferably methylene chloride) is -5 ° C. It is good to start.

In the first drying step, as a method for controlling the residual solvent amount to 35 to 65% by mass, for example, Japanese Patent Publication No. 5-17844 has been described, and the dope is cast on the support. The method of drying for 2 seconds or more from the wind can be mentioned. Moreover, the method etc. which maintain the surface temperature of the said support body at the atmospheric temperature below 40 degreeC until the drying start of a 2nd drying process can be mentioned. The method of maintaining the atmospheric temperature below 40 ° C is more preferably a method of maintaining the atmospheric temperature of 10 ° C to 40 ° C, and the method of maintaining the atmospheric temperature of 15 to 35 ° C is particularly preferable.
Moreover, in the said 1st drying process, it can control according to the drying time of a 1st drying process as a method of controlling the amount of residual solvents to 35-65 mass% in such atmospheric temperature.

The residual solvent amount in the dope film immediately before the second drying step when starting the second drying step is 35 to 65% by mass (however, the residual solvent amount after the first drying step is not exceeded). 50 to 65 mass% is more preferable, and 55 to 65 mass% is more preferable.
The amount of residual solvent in the dope film immediately before the second drying step is preferably 35% by mass or more from the viewpoint of suppressing whitening and suppressing bubble generation, and being 50% by mass or more suppresses whitening, It is more preferable from the viewpoint of suppressing the generation of bubbles. In addition, the amount of residual solvent in the dope film immediately before the second drying step is 50% by mass or more from the viewpoint that whitening can be sufficiently suppressed even when the film thickness of the film of the present invention is reduced to about 20 μm. preferable.
On the other hand, the amount of residual solvent in the dope film immediately before the second drying step is preferably 65% by mass or less from the viewpoint of suppressing whitening.

  From the viewpoint of suppressing whitening, the second drying step is an atmosphere temperature at which the drying start temperature is 40 ° C or higher and exceeds Tg-70 ° C, and is 40 ° C or higher, Tg-50 ° C or higher, and Tg-10 ° C or lower. More preferably, it is particularly preferably 40 ° C. or higher, Tg−40 ° C. or higher, and Tg−20 ° C. or lower from the viewpoint of suppressing whitening and further suppressing bubble generation.

<Peeling process>
The manufacturing method of this invention includes the process of peeling off the dope film | membrane after a 2nd drying process from a support body, and forming a film.
In the production method of the present invention, it is preferable that after the dope is uniformly cast on the support, the dope film is peeled off from the support while being controlled to a specific condition. In the production method of the present invention, the region where the dope is peeled off (hereinafter also referred to as a peeling point) is not particularly limited. Thus, after evaporating the solvent on the support, it is preferable to peel the raw dry dope film (also referred to as web) from the support from the viewpoint of improving the peelability.
The amount of residual solvent in the dope film immediately before the peeling step is preferably less than 20% by mass, and more preferably 20 to 10% by mass.

<Drying process after peeling>
The method for producing a film preferably includes a post-peeling drying step for further drying the film after the peeling step. In addition, after a peeling process after a peeling, you may use as a film as it is, a stretching process may be performed by a well-known method, and a winding process etc. may be performed by a well-known method. About these processes, Unexamined-Japanese-Patent No. 2011-183854 has description.
In the drying step after peeling off, the film peeled off from the support is further dried, and the residual solvent amount is preferably 3% by mass or less, more preferably 1% by mass or less, and further preferably 0.5% by mass or less.

  When the support is a belt-like moving support, the webs peeled off at the peeling position immediately before the belt-like support makes one round pass alternately through a group of rolls arranged in a staggered manner. It is conveyed by a method of conveying, a method of conveying both ends of the peeled web by a clip or the like and conveying them in a non-contact manner. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds. In the drying process after peeling off after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferable. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. Although the drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, it may be appropriately selected according to the type and combination of the solvents used. It is also possible to evaporate the residual solvent by drying with high-temperature air with different temperatures.

[the film]
The film of the present invention is manufactured by the film manufacturing method of the present invention.

(Film thickness)
Although the thickness of the film of this invention can be determined suitably, Preferably it is 20-60 micrometers, More preferably, it is 20-50 micrometers, Especially preferably, it is 20-40 micrometers. It is preferable that the thickness of the film be 60 μm or less because the cost can be reduced.
The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness.

(Tg)
The film of the present invention has a Tg of 90 ° C. or higher, preferably 100 ° C. or higher, more preferably 100 to 290 ° C., and particularly preferably 140 to 170 ° C. (Tg is a film after drying) Of glass transition temperature (unit: ° C.).
The glass transition temperature of the film was measured by adjusting a dynamic viscoelasticity measuring device (Vibron: DVA-225 (IT measurement) after conditioning a dried film sample 24 mm × 36 mm for 2 hours or more at 25 ° C. and a relative humidity of 60%. By Control Co., Ltd.), and the logarithmic axis is stored on the vertical axis based on the storage elastic modulus measured at a distance between grips of 20 mm, a heating rate of 5 ° C./min, a measurement temperature range of 30 ° C. to 350 ° C., and a frequency of 1 Hz The elastic modulus, the temperature is taken along the horizontal axis, and the glass transition temperature Tg is determined by the method described in FIG. 3 of JIS K7121-1987.

(Polarizer)
The film of the present invention is suitable for a protective film for a polarizing plate. The polarizing plate is formed by laminating and laminating a protective film on at least one surface of the polarizer. A conventionally known polarizer can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film is treated with a dichroic dye such as iodine and stretched. The bonding of the film and the polarizer is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.

  The film of the present invention is a protective film for polarizing plate / polarizer / protective film for polarizing plate / liquid crystal cell / film of the present invention / polarizer / protective film for polarizing plate, or protective film for polarizing plate / polarizer / It can use preferably by the structure of the film of this invention / liquid crystal cell / protective film for polarizing plates of this invention / polarizer / protective film for polarizing plates. In particular, when used by being attached to a liquid crystal cell such as a TN type, a VA type, or an OCB type, it is possible to provide a display device that is excellent in viewing angle and visibility with little coloring. Moreover, the polarizing plate using the film of the present invention is less deteriorated under high temperature and high humidity conditions, and can maintain stable performance for a long period of time.

The form of the polarizing plate was produced not only in the form of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also in a continuous form and wound into a roll. A polarizing plate of an embodiment (for example, an embodiment having a roll length of 2500 m or more or 3900 m or more) is also included. In order to use for a large-screen liquid crystal display device, the width of the polarizing plate is preferably 1470 mm or more as described above.
The specific configuration of the polarizing plate is not particularly limited and a known configuration can be adopted. For example, the configuration shown in FIG. 6 of Japanese Patent Application Laid-Open No. 2008-262161 can be adopted.

(Liquid crystal display device)
The film of the present invention can be applied to a liquid crystal display device having a polarizing plate.
The liquid crystal display device is a liquid crystal display device having a liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell, wherein at least one of the polarizing plates is a polarizing plate having the film of the present invention. An IPS, OCB or VA mode liquid crystal display device is preferable.
There is no restriction | limiting in particular as a concrete structure of the liquid crystal display device of this invention, A well-known structure is employable. Further, the configuration described in FIG. 2 of JP-A-2008-262161 can also be preferably employed.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[Synthesis Example 1]
With reference to JP-A-2009-42882, 210 parts of 8-methyl-8-carboxymethyltetracyclo [4.4.0.12.5.17.10] -3-dodecene and 5-phenylbicyclo [2 2.2.1] 40 parts of hept-2-ene, 18 parts of 1-hexene and 750 parts of toluene were charged into a nitrogen-substituted reaction vessel, and the solution was heated to 60 ° C. Subsequently, 0.62 parts of a toluene solution of triethylaluminum (1.5 mol / l) as a polymerization catalyst and tungsten hexachloride modified with t-butanol and methanol (t-butanol: methanol: tungsten) were added to the solution in the reaction vessel. = 0.35 mol: 0.3 mol: 1 mol) of a toluene solution (concentration 0.05 mol / l) 3.7 parts was added, and the system was heated and stirred at 80 ° C. for 3 hours to open the ring. A ring-opening copolymer solution was obtained by copolymerization reaction.
The autoclave was charged with 4000 parts of the ring-opening copolymer solution thus obtained, and 0.48 part of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening copolymer solution. Then, the hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer. The resulting hydrogenated polymer was designated as cycloolefin 1.

[Synthesis Example 2]
With reference to JP 2009-138129 A, a dry toluene solution of 600 g of toluene dehydrated in a 1 L stainless steel reactor in a nitrogen atmosphere and bicyclo [2.2.1] hept-2-ene (0.344 mol) 49.7 ml, 14 g (0.095 mol) of 5-butylbicyclo [2.2.1] hept-2-ene, 4-methyltetracyclo [6.2.13.6.0.2.7] dodeca 43.1 ml of a dry toluene solution of methyl -9-ene-4-carboxylate (0.126 mol) was charged, and ethylene was introduced with stirring until the gauge pressure reached 0.012 MPa. The temperature inside the container was raised to 50 ° C., and a toluene solution of (tricyclopentylphosphine) palladium di (acetate) (5.01 × 10 ⁻³ mmol) and triphenylcarbenium tetrakis (pentafluorophenyl) borate (5.01 × 10 ⁻³ mmol) toluene solution was added and addition copolymerization was carried out at 50 ° C. When the conversion rate to the polymer with respect to the total amount of monomers reached 35%, 31.1 ml of a dry toluene solution of bicyclo [2.2.1] hept-2-ene (0.215 mol) was added, Similarly, when the conversion rate reached 45%, 14 g (0.095 mol) of 5-butylbicyclo [2.2.1] hept-2-ene was added, and when the conversion rate reached 60% in the same manner Then, 26.4 ml of a dry toluene solution of bicyclo [2.2.1] hept-2-ene (0.183 mol) was added. Similarly, when the conversion reached 80%, bicyclo [2.2. 1] 13.5 ml of a dry toluene solution of hepta-2-ene (0.094 mol) was added. Similarly, when the conversion reached 90%, bicyclo [2.2.1] hept-2-ene ( 0.064 mol) of dry toluene Was added, and when the conversion rate reached 95%, 7.0 ml of a dry toluene solution of bicyclo [2.2.1] hept-2-ene (0.048 mol) was added and added. The copolymerization reaction was carried out for a total of 7 hours. After completion of the reaction, unreacted monomers were quantified and the addition rate was determined. The conversion rate was 99%. The reaction solution diluted with toluene was coagulated with 4 L of isopropyl alcohol and then dried under vacuum at 95 ° C. for 20 hours to obtain 146 g of a hydrogenated polymer. The resulting hydrogenated polymer was designated as cycloolefin 2.

[Synthesis Example 3]
With reference to JP 2011-202012 A, 100 parts by mass of toluene, 100 parts by mass of 1-adamantyl methacrylate, and 3 parts by mass of thioglycol as a chain transfer agent were charged into a four-necked flask. Then, after stirring at 70 ° C. for 1 hour in a nitrogen atmosphere, 0.2 part by mass of azobisisobutyronitrile as a thermal polymerization initiator is added and reacted for 2 hours at 70 ° C., followed by 2 at 80 ° C. Reacted for hours. Thereafter, the reaction solution was added to a temperature atmosphere of 130 ° C., and toluene, the chain transfer agent, and the unreacted monomer were removed by drying to obtain an acrylic polymer. The resulting acrylic polymer was designated as acrylic 3.

[Example 1]
JSR ARTON G7810 (Arton in the following table) was dissolved in methylene chloride containing 8% by mass of methanol while stirring at 25 ° C. to obtain a transparent dope having a concentration of 20% by mass. This dope was cast on a glass substrate using an applicator and dried at an ambient temperature of 25 ° C. for 1 minute. A part of this film was cut out and the amount of residual solvent was measured. After drying at 25 ° C., it was dried for 6 minutes in a drying zone having a drying start temperature of 130 ° C. The film was peeled from the substrate, and the peeled film was dried at 140 ° C. for 30 minutes to obtain the synthetic polymer film of Example 1. The produced film had a residual solvent amount of 0.0% and a film thickness of 40 μm.

[Example 2]
A synthetic polymer film of Example 2 was obtained in the same manner as in Example 1 except that the film was dried at an ambient temperature of 25 ° C. and then dried at 110 ° C. for 6 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 3]
A synthetic polymer film of Example 3 was obtained in the same manner as in Example 1 except that it was dried at an ambient temperature of 25 ° C. and then dried at 150 ° C. for 6 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 4]
A synthetic polymer film of Example 4 was obtained in the same manner as in Example 1 except that methylene chloride containing 2% by mass of methanol was used as a solvent. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 5]
A synthetic polymer film of Example 5 was obtained in the same manner as in Example 1 except that methylene chloride containing 4% by mass of methanol was used as a solvent. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 6]
A synthetic polymer film of Example 6 was obtained in the same manner as in Example 1 except that methylene chloride containing 6% by mass of methanol was used as a solvent. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 7]
A synthetic polymer film of Example 7 was obtained in the same manner as in Example 1 except that methylene chloride containing 10% by mass of methanol was used as a solvent. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 8]
A synthetic polymer film of Example 8 was obtained in the same manner as in Example 1 except that methylene chloride containing 13% by mass of methanol was used as a solvent. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 9]
Using the hydrogenated polymer (cycloolefin 1) obtained in Synthesis Example 1 instead of Arton, it was dried at an ambient temperature of 25 ° C. for 1 minute, and then dried in a drying zone at a drying start temperature of 280 ° C. for 6 minutes. Except for the above, a synthetic polymer film of Example 9 was obtained in the same manner as in Example 1. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 10]
Instead of the dope of Example 1, a dope prepared by dissolving the hydrogenated polymer (cycloolefin 2) obtained in Synthesis Example 2 in methylene chloride containing 8% by mass of ethanol was cast and 1 at an ambient temperature of 25 ° C. A synthetic polymer film of Example 10 was obtained in the same manner as in Example 1 except that the film was dried for 6 minutes and then dried in a drying zone at a drying start temperature of 80 ° C. for 6 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 11]
After adding 30% by mass of ARTON G7810 from JSR and 2,6-diphenylphenol (additive 1 in Table 1 below) to ARTON G7810 in methylene chloride containing 8% by mass of methanol, the mixture was stirred at 25 ° C. This was dissolved to obtain a transparent dope having a concentration of 20% by mass. This dope was cast on a glass substrate using an applicator, dried at an ambient temperature of 25 ° C. for 1 minute, and dried in a drying zone at a drying start temperature of 40 ° C. for 6 minutes. The film was peeled from the substrate, and the peeled film was dried at 120 ° C. for 30 minutes to obtain a synthetic polymer film of Example 11. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 12]
The acrylic polymer (acrylic 3) obtained in Synthesis Example 3 was dissolved in methylene chloride containing 13% by mass of methanol while stirring at 25 ° C. to obtain a transparent dope having a concentration of 16% by mass. This dope was cast on a glass substrate using an applicator, dried at an ambient temperature of 25 ° C. for 1 minute, and dried in a drying zone at a drying start temperature of 110 ° C. for 6 minutes. The film was peeled from the substrate, and the peeled film was dried at 120 ° C. for 30 minutes to obtain a synthetic polymer film of Example 12. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 13]
In a methylene chloride containing 8% by mass of methanol, a methyl methacrylate-styrene (60:40) copolymer (Nippon Steel & Sumikin Chemical Co., Ltd. Estyrene MS-600, acrylic-styrene in the following table) is dissolved with stirring at 25 ° C. Thus, a transparent dope having a concentration of 20% by mass was obtained. This dope was cast on a glass substrate using an applicator, dried at an ambient temperature of 25 ° C. for 1 minute, and dried in a drying zone at a drying start temperature of 70 ° C. for 6 minutes. The film was peeled from the substrate, and the peeled film was dried at 120 ° C. for 30 minutes to obtain a synthetic polymer film of Example 13. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Comparative Example 1]
JSR ARTON G7810 was dissolved in methylene chloride with stirring at 25 ° C. to obtain a transparent dope having a concentration of 20% by mass. This dope was cast on a glass substrate using an applicator, dried at an ambient temperature of 25 ° C. for 1 minute, and dried in a drying zone at a drying start temperature of 110 ° C. for 6 minutes. The film was peeled from the substrate, and the peeled film was dried at 120 ° C. for 30 minutes to obtain a synthetic polymer film of Comparative Example 1. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Comparative Example 2]
A synthetic polymer film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the film was dried at an ambient temperature of 25 ° C. for 1 minute and then dried in a drying zone at a drying start temperature of 95 ° C. for 6 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Comparative Example 3]
When JSR ARTON G7810 was dissolved in methylene chloride containing 20% by mass of methanol, the dope was whitened and undissolved, and no film was formed.

[Comparative Example 4]
A synthetic polymer film of Comparative Example 4 was obtained in the same manner as in Example 9, except that the film was dried at an ambient temperature of 25 ° C. for 1 minute and then dried in a drying zone at a drying start temperature of 40 ° C. for 6 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Comparative Example 5]
A synthetic polymer film of Comparative Example 5 was obtained in the same manner as in Example 12 except that the film was dried at an ambient temperature of 25 ° C. for 1 minute and then dried in a drying zone at a drying start temperature of 40 ° C. for 6 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Comparative Example 6]
A synthetic polymer film of Comparative Example 6 was obtained in the same manner as in Example 13 except that the film was dried at an ambient temperature of 25 ° C. for 1 minute and then dried in a drying zone at a drying start temperature of 30 ° C. for 6 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

  The dope compositions and production conditions used in Examples 1 to 13 and Comparative Examples 1 to 6 are summarized in Table 1 below.

[Example 14]
A synthetic polymer film of Example 14 was obtained in the same manner as in Example 1 except that the film thickness was set to half that of Example 1. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 20 μm.

[Example 15]
A synthetic polymer film of Example 15 was obtained in the same manner as in Example 1 except that the film thickness was set to 1.5 times that of Example 1. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 50%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 60 μm.

[Example 16]
A synthetic polymer film of Example 16 was obtained in the same manner as in Example 1 except that the drying time at 25 ° C. was shortened from 1 minute to 45 seconds. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 65%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Example 17]
A synthetic polymer film of Example 17 was obtained in the same manner as in Example 1 except that the drying time at 25 ° C. was increased from 1 minute to 2 minutes. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 35%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Comparative Example 7]
A synthetic polymer film of Comparative Example 7 was obtained in the same manner as in Example 1 except that the drying time at 25 ° C. was further shortened from 1 minute to 30 seconds than in Example 16. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 80%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

[Comparative Example 8]
A synthetic polymer film of Comparative Example 8 was obtained in the same manner as in Example 1 except that the drying time at 25 ° C. was further increased from 1 minute to 5 minutes as compared with Example 17. The residual solvent amount of the film after drying at an ambient temperature of 25 ° C. was 25%, the residual solvent amount of the produced film was 0.0%, and the film thickness was 40 μm.

  The dope compositions and production conditions used in Examples 14 to 17 and Comparative Examples 7 and 8 are summarized in Table 2 below together with Example 1.

[Evaluation]
(Glass transition temperature of synthetic polymer film)
The glass transition temperature was measured by the following method. After adjusting the synthetic polymer film sample 24 mm × 36 mm of each Example and Comparative Example for 2 hours or more at 25 ° C. and 60% relative humidity, a dynamic viscoelasticity measuring device (Vibron: DVA-225 (IT Measurement Control Co., Ltd.) The storage elastic modulus was measured at a distance between grips of 20 mm, a heating rate of 5 ° C./min, a measurement temperature range of 30 ° C. to 350 ° C., and a frequency of 1 Hz. Taking the storage elastic modulus on the logarithmic axis on the vertical axis and the temperature on the linear axis on the horizontal axis, the glass transition temperature Tg was determined by the method described in FIG. 3 of JIS K7121-1987.

(Whitening of synthetic polymer film)
The whitening of the synthetic polymer film is evaluated by the following method.
The surface of the synthetic polymer film was visually observed and evaluated in the following three stages. It is required practically that it is A evaluation.
A: Transparent B: Foamed, poor surface appearance C: White

(Bubble in synthetic polymer film)
Bubbles are evaluated by the following method.
The synthetic polymer film was cut perpendicularly to the thickness direction, the cross-section was observed with an optical microscope (50 times magnification), the cross-sectional image was observed over 150 μm in the width direction, and the state of bubbles was evaluated in three stages. It is required practically that it is A or B evaluation.
A: No bubbles B: Traces of collapsed bubbles exist C: Bubbles with a length of 1 μm or more exist

(Removal of the synthetic polymer film from the support)
The peeling from the support was measured by the following method.
The synthetic polymer film was peeled off from the support by hand and evaluated in the following five stages. A to C evaluation is required practically.
A: Peeling very light B: Peeling light C: Peeling slightly heavy D: Peeling heavy E: Peeling very heavy

(Residual solvent amount in the synthetic polymer film)
The amount of residual solvent in the film is represented by the following formula.
Residual solvent amount = residual volatile matter mass / film mass after heat treatment × 100%
The residual volatile matter mass is a value obtained by subtracting the film mass after the heat treatment from the film mass before the heat treatment when the film is heat-treated at 120 ° C. for 2 hours.

From the above examples of Table 1 and Table 2, when forming a solution film using methylene chloride, a specific alcohol is further used as a solvent in a specific quantitative ratio to improve the peelability, and a specific residual The entire film after casting when forming a film with excellent heat resistance by increasing the drying start temperature for the dope film that has reached the amount of solvent so that the methylene chloride does not evaporate before the alcohol. It was found that suppression of whitening, suppression of bubble generation and improvement of peelability from the support can be achieved at the same time.
On the other hand, it was found from Comparative Example 1 that if no alcohol was added to the dope, the peelability from the support was very poor.
From Comparative Examples 2 and 4 to 6, when the drying start temperature is lower than the lower limit of the present invention in the second drying step, the fluidity of the dope film is insufficient (it reaches the Tg of the dope film when containing the solvent). It was found to be white.
From Comparative Example 3, it was found that when the amount of alcohol added to methylene chloride exceeded the upper limit of the present invention, a polymer such as an acrylic resin was not dissolved and film formation was impossible.
From Comparative Example 7, it was found that when the residual solvent amount at the start of drying in the second drying step exceeded the upper limit of the present invention, whitening was eliminated, but foaming occurred.
From Comparative Example 8, when the residual solvent amount at the start of drying in the second drying step is lower than the lower limit of the present invention, the dope film has insufficient fluidity (the solvent is expected to decrease depending on the residual solvent amount). It was estimated that the Tg of the dope film became higher than the drying temperature of the second drying step and stopped flowing), and the entire film after casting was whitened and bubbles were generated.

Claims (8)

Casting a dope containing any one of cycloolefin resin, acrylic resin and acrylic-styrene copolymer resin and a solvent onto a support;
A first drying step of forming a dope film in which the dope after casting is maintained at an atmospheric temperature of less than 40 ° C. and a residual solvent amount is controlled to 35 to 65% by mass;
When the dope film after the first drying step has a residual solvent amount of 35 to 65% by mass (however, it does not exceed the residual solvent amount after the first drying step), the drying start temperature of the dope film A second drying step of drying at an atmospheric temperature of 40 ° C. or higher and exceeding Tg−70 ° C .;
Including peeling the dope film after the second drying step from the support to form a film,
1 to 13% by mass of the solvent is an alcohol having an average carbon number of 1 to 4,
Tg of said film is 90 degreeC or more, However, Tg represents the glass transition temperature (unit: degreeC) of the film after drying.   2. The method for producing a film according to claim 1, wherein the drying start temperature in the second drying step is 40 ° C. or more and Tg−50 ° C. or more and Tg−10 ° C. or less. The glass transition temperature (unit: ° C.) of the film after drying.   Tg of the said film is 100-290 degreeC, The manufacturing method of the film of Claim 1 or 2 (however, Tg represents the glass transition temperature (unit: degreeC) of the film after drying).   4-10 mass% of the said solvent is the said C1-C4 alcohol, The manufacturing method of the film as described in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing a film according to any one of claims 1 to 4, wherein the alcohol contained in the solvent is an alcohol having an average carbon number of 1 to 2.   The film thickness of the said film is 20-60 micrometers, The manufacturing method of the film as described in any one of Claims 1-5 characterized by the above-mentioned.   The method for producing a film according to any one of claims 1 to 6, wherein a residual solvent amount immediately before the second drying step is 50 to 65 mass%.   The method for producing a film according to claim 1, wherein 1% by mass or more of the dope is a moisture permeation reducing compound.