JP2006297920A - Polymer film and method for manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a film which is excellent in flatness and optical property and has reduced foreign matter and scratches. <P>SOLUTION: The film is manufactured by casting a dope comprising a cellulose acylate, a solvent and an additive to form a cast film, peeling a wet film 17 containing the solvent with a peel roller 52 and drying it. The wet film 17 is transferred to a transfer part 53 having a plurality of pass rollers 91-97. The surface temperature of each pass roller 91-97 is adjusted by a temperature adjusting function provided to each. The surface temperature is maintained by heating within the range between the melting point of the additive Tm and Tm+50°C. When the wet film 17 is dried during transferring while supporting it with each pass roller 91-97, stabilization at transfer can be attained and a film which has reduced roller transfer defect and push scars defect and is excellent in flatness and optical property can be manufactured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polymer film and a method for producing the same.

  Liquid crystal display devices have low voltage and low power consumption, and have advantages such as miniaturization and thinning, so they are widely used for monitors of personal computers and portable devices, and for television applications. . In general, a liquid crystal display device is composed of an optical material such as a liquid crystal cell, an optical compensation sheet, and a polarizer. In the technical field of such an optical material, protection of a polarizing plate, elimination of image coloring, expansion of a viewing angle, etc. Various polymer films are used depending on the application.

  Cellulose acylate film, which is a typical example of polymer film, has advantages such as high birefringence and high retardation value, and can be a protective film for polarizing plates. It is widely used as a polymer film that can provide a display device. Specific examples of the cellulose acylate liquid crystal display device include a protective film for a polarizing plate, a color filter, and a protective film for a liquid crystal display device for a personal computer. In particular, the use as a protective film of a liquid crystal display device has increased remarkably in recent years. In addition, it is not just a protective film, but a film (for example, WV film manufactured by Fuji Photo Film Co., Ltd.) that can widen the viewing angle, an antireflection film for a liquid crystal television (for example, CV film manufactured by Fuji Photo Film), etc. Cellulose acylate films that are used by adding new functions to the films themselves are also increasing.

  Such a polymer film including a cellulose acylate film is mainly produced by a solution casting method. The solution casting method is a method in which a dope produced by filtering a polymer solution obtained by mixing a polymer such as cellulose acylate, a solvent, and an additive with a filtration device is cast on a traveling support and then containing a solvent. The film is peeled off as a damp film (wet film) and further dried by a drying facility to produce a film.

  In order to improve the optical characteristics (mainly retardation value) during the production of the film, the film is stretched when the wet film is dried as described above. Further, when a film such as a wet film is dried, a plurality of drying regions having different temperatures are provided, and the inside is continuously transported to dry stepwise. As the drying region, for example, a plurality of pass rollers are provided, and a transfer portion to be dried while transporting while supporting the wet film, and a predetermined residual solvent amount while gripping both side ends of the film. There is a tenter to be dried and a drying chamber to be sufficiently dried. Hereinafter, in the present invention, the drying process in the transition part, the tenter, and the drying chamber is referred to as a first drying process, a second drying process, and a third drying process in this order.

At the time of such drying, the solvent can be efficiently volatilized and the film can be dried while suppressing the occurrence of wrinkles, wrinkles, curls, etc., so the surface temperature of the film is apparent Tg A method of raising the temperature to (° C.) or higher is used. The apparent Tg means Tg in a composite material composed of a plurality of materials having different Tg, such as cellulose acylate film. In the following Patent Document 1, a roll conveying means arranged in a staggered manner is provided between the time when the film containing the solvent is peeled off and the film is dried, and the surface temperature of the film is maintained at 50 ° C. to 100 ° C., A method is described in which the film can be dried while curling of the film is suppressed by conveying the film at a passage time of 10 to 70 seconds.
JP 2001-315147 A

  However, when the film is heated at a high temperature, as in the method described in Patent Document 1 or when the temperature is increased to an apparent Tg or higher, not only the solvent but also the additive is volatilized, and it is in a dry atmosphere such as the inside of the drying equipment. Scatter. Among them, a plasticizer, which is one of the additives, tends to volatilize because there are many substances having a low boiling point.

  Since there is no separation in the transition part, when the concentration of the plasticizer gas volatilized in the tenter (hereinafter referred to as gas concentration) increases, the gas concentration in the transition part also increases in proportion. On the other hand, at the time of drying, the surface temperature of the film is lowered due to latent heat of vaporization when additives such as a solvent and a plasticizer volatilize. Therefore, a phenomenon occurs in which the pass roller supporting the film is cooled by the latent heat of vaporization at the transition portion.

  When the scattered plasticizer gas comes into contact with the surface of the pass roller thus cooled, the plasticizer gas is condensed and attached or deposited. As described above, when a deposit of plasticizer gas or a massive deposit (hereinafter collectively referred to as gas foreign matter) is present on the surface of the pass roller, this gas is applied to the surface of the film conveyed while being supported by the pass roller. Since the foreign matter comes into contact with the film, it may be transferred to the film surface (roller defect) or scratched (push defect). As a result, there is a problem that these become surface defects of the film and the optical characteristics are remarkably deteriorated.

  In the present invention, when the film is dried while being transported while being supported by a plurality of pass rollers (first drying process), the occurrence of a roller imprint defect or a pressing flaw defect is suppressed on the film surface, and the surface defect is reduced. Provided is a method for producing a polymer film, which can obtain a film having excellent flatness and optical properties.

  In the method for producing a polymer film of the present invention, a cast film is formed by casting a polymer solution in which a polymer, a solvent, and an additive are mixed, on a running support, and the cast film is continuously formed from the support. In the method for producing a polymer film having a first drying step in which a film containing a solvent is peeled off and then the film containing the solvent is dried, in the first drying step, a plurality of temperature control functions are individually provided. The film is dried while the film containing the solvent is conveyed while adjusting the surface temperature of the pass roller by the pass roller. When the melting point of the additive is Tm (° C.), the surface temperature of the pass roller is preferably Tm (° C.) or more and Tm + 50 ° C. or less.

  In addition, a second drying step is performed after the first drying step, and in the second drying step, drying is performed by a drying facility while the both side ends of the film containing the solvent are conveyed while being gripped by a gripping member. It is preferable that the heating temperature of the film is substantially constant at least while the width of the film is displaced. The polymer is preferably cellulose acylate. The polymer film of the present invention is preferably produced using any one of the methods described above.

  In the present invention, when a wet film is formed from a polymer solution in which a polymer, a solvent, and an additive are mixed, and the wet film is dried to produce a film, the temperature is individually measured at a transition portion that is one of the drying steps. The plurality of pass rollers having an adjusting function are dried while supporting and transporting the wet film while adjusting the surface temperature of the pass roller, so that the transport at the crossing portion can be stabilized. it can.

  Further, the surface temperature of the pass roller is set to be not less than Tm (° C.) and not more than Tm + 50 (° C.) with respect to the melting point Tm (° C.) of the additive (mainly plasticizer). Even if the additive gas is condensed on the pass roller, it can immediately melt and re-scatter or evaporate. Therefore, it is possible to suppress the additive component from adhering or depositing on the surface of the pass roller, so that the surface can be kept smooth and clean. Therefore, it is possible to suppress the transfer to the film or the generation of scratches, so that it is possible to produce a film particularly excellent in flatness. In practice, the additive gas melts upon contact on the pass roller and is uniformly coated on the surface. The melted plasticizer gas may adhere to the film surface in a liquid state, but it does not develop into a planar defect, and there is no problem in quality. In the drying process, since the film is always heated, it is presumed that the liquid plasticizer adhering to the surface is scattered again or penetrates into the film.

  Embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment.

As a material constituting the dope used in the present invention, cellulose acylate is preferably used, and the cellulose acylate in which the substitution degree of acyl group to the hydroxyl group of cellulose satisfies all of the following formulas (I) to (III). It is preferable to use a rate.
(I): 2.5 ≦ A + B ≦ 3.0
(II): 0 ≦ A ≦ 3.0
(III): 0 ≦ B ≦ 2.9
However, A and B in a formula represent the ratio by which the hydrogen in the hydroxyl group of a cellulose is substituted by the acyl group, A is a substitution degree of an acetyl group, B is a C2-C22 acyl group. Is the degree of substitution. In addition, it is preferable to use the cellulose acylate whose ratio of the particle | grains of 0.1 mm or more and 4 mm or less is 90 mass% or more with respect to the total weight.

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer in which part or all of these hydroxyl groups are esterified with an acyl group having 2 or more carbon atoms. The degree of acyl substitution means the ratio at which the hydroxyl group of cellulose is esterified at each of the 2-position, 3-position and 6-position (in the case of 100% esterification, the substitution degree is 1).

  The total acyl substitution degree, that is, the value of DS2 + DS3 + DS6 is preferably 2.00 to 3.00, more preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88. Moreover, the value of D6S / (DS2 + DS3 + DS6) is preferably 0.28 or more, more preferably 0.30 or more, and particularly preferably 0.31 to 0.34. Here, DS2 is a ratio in which the hydrogen of the hydroxyl group at the 2-position is substituted with an acyl group in the glucose unit (hereinafter referred to as the acyl substitution degree at the 2-position), and DS3 is the 3-position of the glucose unit. This is the ratio at which the hydrogen at the hydroxyl group is replaced by an acyl group (hereinafter referred to as the degree of acyl substitution at the 3-position), and DS6 is the ratio at which the hydrogen at the hydroxyl group at the 6-position is replaced by an acyl group in the glucose unit. (Hereinafter referred to as the acyl substitution degree at the 6-position).

  The cellulose acylate may have only one type of acyl group, or may contain two or more types of acyl groups. When there are two or more types of acyl groups, one of them is preferably an acetyl group. The total number of substitutions of hydroxyl groups at the 2nd, 3rd and 6th positions by acetyl groups is DSA, and the total number of substitutions of the 2nd, 3rd and 6th hydroxyl groups by acyl groups other than acetyl groups When DSB is DSB, the value of DSA + DSB is preferably 2.22 to 2.90, and more preferably 2.40 to 2.88. The DSB is preferably 0.30 or more, particularly preferably 0.7 or more. Further, 20% or more of DSB is preferably a substituent at the 6-position hydroxyl group, more preferably 25% or more, further preferably 30% or more, and particularly preferably 33% or more. Further, the DSA + DSB value at the 6-position of the cellulose acylate is preferably 0.75 or more, more preferably 0.80 or more, and particularly preferably 0.85 or more. By using these cellulose acylates, an excellent soluble cellulose acylate solution can be prepared. The cellulose acylate may be obtained from either one of linter cotton or pulp cotton, or may be a mixture of both, but is preferably obtained from linter cotton.

  The acyl group having 2 or more carbon atoms of the cellulose acylate in the present invention may be an aliphatic group or an aryl group, and is not particularly limited. For example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester and the like may be mentioned, and each may further have a substituted group. Preferred examples of these include propionyl group, butanoyl group, pentanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, iso-butanoyl group , T-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a t-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and a propionyl group and a butanoyl group are particularly preferable. It is.

  Solvents for dissolving cellulose acylate include aromatic hydrocarbons (eg benzene, toluene, etc.), halogenated hydrocarbons (eg dichloromethane, chloroform, chlorobenzene etc.), alcohols (eg methanol, ethanol, n-propanol, n -Butanol, diethylene glycol, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), esters (eg, methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (eg, tetrahydrofuran, methyl cellosolve, etc.).

  In the above halogenated hydrocarbons, halogenated hydrocarbons having 1 to 7 carbon atoms and dichloromethane are preferably used. From the viewpoints of physical properties such as solubility of cellulose acylate, peelability from cast film support, mechanical strength of the film, and optical properties, one or more alcohols having 1 to 5 carbon atoms in addition to dichloromethane It is preferable to mix several types. The content of the alcohol is preferably 2% by mass or more and 25% by mass or less, and more preferably 5% by mass or more and 20% by mass or less with respect to the entire solvent. Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, and n-butanol, but methanol, ethanol, n-butanol, or a mixture thereof is preferably used.

  Recently, a solvent composition not using dichloromethane has been proposed in order to minimize the influence on the environment. In this case, an ether having 4 to 12 carbon atoms, a ketone having 3 to 12 carbon atoms, and an ester having 3 to 12 carbon atoms are preferable, and these are used by appropriately mixing them. These ethers, ketones and esters may have a cyclic structure. A compound having any two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as a solvent. The solvent may have another functional group such as an alcoholic hydroxyl group. When a solvent having two or more types of functional groups is used, the number of carbon atoms may be within the specified range of the compound having any functional group.

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148. These descriptions can be applied to the present invention. The same applies to additives such as solvents and plasticizers, deterioration inhibitors, UV absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, release accelerators, etc. JP-A-2005-104148 describes in detail in paragraphs [0196] to [0516]. These descriptions can be applied to the present invention.

  The cellulose acylate film produced according to the present invention is used for a polarizing plate or a liquid crystal display member because of its excellent flatness and optical properties. For the purpose of preventing these deteriorations, an ultraviolet absorber is preferably used. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Examples of the ultraviolet absorber preferably used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

  Examples of benzotriazole ultraviolet absorbers are shown below, but the present invention is not limited to these. 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3) '-Tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy -3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethyl) Butyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl)- -Chlorobenzotriazole, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoyl) Phenylmethane), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 2 (2'-hydroxy- 3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, (2 (2'-hydroxy-3', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole, 2, 6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert- Til-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3 , 5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl- 4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy- Hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4) -Hydroxybenzyl) -isocyanurate and the like. In particular, (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 2 (2'-hydroxy-3 ' , 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, (2 (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole, 2,6- Di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert- Butyl-5-methyl-4-hydroxyphenyl) propionate] and N, N′-bis [3- (3,5-di-tert-butyl). Le 4-hydroxyphenyl) may be used in combination with phosphorus-based processing stabilizer such as metal hydrazine systems such as propionyl] hydrazine deactivator and tris (2,4-di -tert- butylphenyl) phosphite.

Further, ultraviolet absorbers described in JP-A-6-148430 and JP-A-7-11056 can also be preferably used. Among the above description, the ultraviolet absorber preferably used in the present invention has high transparency, is excellent in the effect of preventing the deterioration of the polarizing plate and the liquid crystal element, and has less unnecessary coloring, and the benzotriazole-based ultraviolet absorber. It is an agent. The amount of the UV absorber used is not uniform depending on the type of compound and the use conditions, but is usually preferably 0.2 g or more and 5.0 g or less, more preferably 1 g ² per 1 m ^{2 of} cellulose acylate film. 0.4 g or more and 1.5 g or less, particularly preferably 0.6 g or more and 1.0 g or less.

  Examples of other additives include the light stabilizers listed in the catalog of “Adeka Stub”, an outline of additives for Asahi Denki Plastics, but the light stabilizers and UV absorbers listed in the Chibin Special Chemicals Tinuvin product guide are also used. be able to. In addition, SESORB, SEENOX, SEETEC in the catalog of SHIPRO KASEI KAISHA, UV absorbers and antioxidants of Johoku Chemical Industry, VIOSORB of joint chemicals, and UV absorbers of Yoshitomi Pharmaceutical can be preferably used.

  The temperature at which the cellulose acylate solution is prepared is preferably 0 ° C. or higher and 150 ° C. or lower, more preferably 0 ° C. or higher and 100 ° C. or lower, and further 0 ° C. or higher and 90 ° C. or lower. Although it is preferable, it is particularly preferably 20 ° C. or higher and 90 ° C. or lower. Moreover, when adjusting this cellulose acylate solution, it is preferable not to use a base, but when using a base, either an organic base or an inorganic base may be used. However, it is more preferable to use an organic base, and examples thereof include pyridine, tertiary alkylamine (preferably triethylamine, ethyldiisopropylamine) and the like.

The optical properties of the cellulose acylate film of the present invention are as follows. It is preferable to satisfy.
(IV): Re (λ) = (nx−ny) × d
(V): Rth (λ) = {(nx + ny) / 2−nz} × d
(VI): 46 nm ≦ Re (630) ≦ 200 nm
(VII): 70 nm ≦ Rth (630) ≦ 350 nm
Re (λ) in the formula (IV) is the front retardation value (unit: nm) at the wavelength λnm, and Rth (λ) in the formula (V) is the retardation value in the film thickness direction at the wavelength λnm ( Unit; nm). Also, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film refractive index. Is the thickness. More preferably, the following formulas (VIII) and (IX) are satisfied.
(VIII): 46 nm ≦ Re (630) ≦ 100 nm
(IX): 180 nm ≦ Rth (630) ≦ 350 nm

Although the optical characteristic values of Re and Rth change with changes in mass and dimensional changes due to changes in humidity and aging at high temperatures, the smaller the change in the values of Re and Rth, the better. In order to reduce the change in the optical property value due to humidity, the cellulose acylate having a high degree of acyl substitution at the 6-position and various hydrophobic additives (plasticizers, retardation control agents, ultraviolet absorbers, etc.) can be used. Reduce moisture permeability and equilibrium moisture content. The moisture permeability is preferably 400 g or more and 2300 g or less per square meter at 60 ° C. and 95% RH for 24 hours, and the equilibrium moisture content is preferably 3.4% or less at 25 ° C. and 80% RH. . In addition, when the humidity at 25 ° C. is changed from 10% RH to 80% RH, the amount of change in optical characteristics is preferably 12 nm or less in Re value and 32 nm or less in Rth value. The amount of the hydrophobic additive is preferably 10% by weight or more and 30% by weight or less, more preferably 12% by weight or more and 25% by weight or less, and particularly preferably 14.5% or less with respect to the cellulose acylate. % By weight or more and 20.0% by weight or less. Further, when the additive has volatility or decomposability, a change in the mass or dimensional change of the film occurs, resulting in a change in optical characteristics. Accordingly, the mass change amount is preferably 5% by weight or less after 48 hours at 80 ° C. and 90% RH, and the dimensional change amount is 5% after 24 hours at 60 ° C. and 95% RH. % Or less is preferable. Even if there is a small dimensional change or mass change, if the photoelastic coefficient of the film is small, the amount of change in optical characteristics is small. Therefore, the photoelastic coefficient of the film is preferably 50 × 10 ⁻¹³ cm ² / dyne or less.

  In FIG. 1, the flow of the manufacturing process of the cellulose acylate film in this invention is shown. The film production process in the present invention is roughly divided into a dope production process 12, a casting process 14, a stripping process 16, and a drying process 18. Details of these steps will be described later.

  In the dope manufacturing step 12, cellulose acylate, which is the main component of the film, a solvent, and an additive are mixed to form a cellulose acylate solution, which is filtered by a filtering device having a metal filter to manufacture a dope 13.

  Next, in the casting step 14, the dope 13 is cast on a support to form a casting film 15. After the cast film 15 has a self-supporting property, it is continuously peeled off from the support to obtain a wet film 17 containing a solvent. Subsequently, the wet film 17 is sent to a drying process 18 composed of a plurality of drying regions having different heating temperatures and the like, and the solvent in the wet film 17 is evaporated in each drying region, whereby the film 19 is manufactured.

  FIG. 2 shows a dope production line 20 for performing the dope production process 12. However, the manufacturing method of dope which can be used by this invention is not limited to the form shown in FIG. The dope production line 20 includes a solvent tank 21, an additive tank 22, a hopper 23, a dissolution tank 24, a filtration device 25, and a stock tank 26. These various devices constituting the dope production line 20 are connected by a plurality of pipes.

  Various materials constituting the dope 13 are stored in the solvent tank 21, additive tank 22, and hopper 23, respectively. The solvent tank 21 stores a solvent for dissolving the cellulose acylate. As this solvent, for example, a mixed solvent in which dichloromethane is used as a main solvent and alcohols are mixed therewith is used. Additives are stored in the additive tank 22. Examples of such additives include plasticizers, retardation control agents, ultraviolet absorbers (for example, benzotriazole compounds), matting agents (for example, silica particles), deterioration inhibitors, optical anisotropy control agents, and dyes. And a release agent. These are appropriately selected according to the purpose and used. Further, in the hopper 23, cellulose acylate which is the main raw material of the film is stored.

  The solvent is fed from the solvent tank 21 to the dissolution tank 24 by opening the valve 30. At this time, the amount of the solvent is adjusted by the valve 30. Subsequently, the valve 31 is opened to send the additive from the additive tank 22 to the dissolution tank 24, and then the hopper 23 is opened to send the cellulose acylate to the dissolution tank 24.

  When the additive is liquid at room temperature, it can be fed into the dissolution tank 24 in a liquid state. Moreover, when the said additive is solid, it can also send in to the dissolution tank 24 using a hopper. In addition, when using a plurality of types of additives, a solution in which a plurality of types of additives are dissolved may be placed in the additive tank 22, and the valve 31 may be appropriately adjusted and sent out. Depending on the type, a plurality of additive tanks containing a solution in which these additives are dissolved are prepared, and the various additive tanks and the dissolution tank 24 are connected by a pipe provided with a valve. It can also be fed by adjusting the valve.

  The order in which the solvent, additive, and cellulose acylate that are the raw materials of the dope 13 are mixed is not particularly limited. In the present embodiment, the solvent, the additive, and the cellulose acylate are sent to the dissolution tank 24 in this order and mixed. However, as other methods, for example, a predetermined amount of cellulose acylate is used. A cellulose acylate solution can be prepared by sending a predetermined amount of solvent and additive after being sent to the dissolution tank 24, or a mixed solution in which a solvent and an additive are mixed in advance is prepared. An acylate may be mixed. In addition, a solvent may be added to a mixture of cellulose acylate and an additive, and an additive may be appropriately added in the subsequent film production process 50 (see FIG. 3). There is no particular limitation in the case.

  The dissolution tank 24 is provided with a jacket 32 disposed on the outer periphery thereof so as to cover it, a first stirring blade 34 rotated by a motor 33, and a second stirring blade 36 rotated by a motor 35. The first stirring blade 34 is preferably an anchor blade, and the second stirring blade 36 is preferably a dissolver type eccentric stirring machine. The jacket 32 has a temperature adjustment function, and thereby adjusts the internal temperature of the dissolution tank 13. In the present embodiment, as the temperature adjusting function, a heat transfer medium is flowed into the jacket 32 to adjust the temperature in the dissolution tank 13 to a range of −10 ° C. to 55 ° C. The motor 33 or the motor 35 is selected as appropriate, and the first stirring blade 34 and the second stirring blade 36 are rotated to produce a swelling liquid 37 in which cellulose acylate is swollen in a solvent.

  The swelling liquid 37 is fed to the heating device 41 using the pump 40. The heating device 41 has a function of pressurizing the swelling liquid 37 while using a pipe with a jacket. Although it will not specifically limit if the heating apparatus 41 is a form which can hold | maintain the swelling liquid 37 at predetermined | prescribed temperature, It is preferable to have a function which can be pressurized like this embodiment. Thus, the cellulose acylate solution 42 in which the cellulose acylate is sufficiently dissolved in the solvent can be produced by holding the swelling liquid 37 under heating or pressure heating conditions. At this time, the temperature of the swelling liquid 37 is preferably 0 ° C. or higher and 97 ° C. or lower. In addition, the cooling solution method which melt | dissolves a cellulose acylate in a solvent can also be implemented by cooling the swelling liquid 37 to the temperature of -150 degreeC or more and -10 degrees C or less. When such a heating dissolution method or a cooling dissolution method is appropriately selected and performed, the cellulose acylate can be sufficiently dissolved in the solvent. Further, a temperature controller 43 is provided downstream of the heating device 41, and thereby the temperature of the cellulose acylate solution 42 is set to substantially room temperature. Subsequently, the cellulose acylate solution 42 having a substantially room temperature is sent to the filtration device 25 by opening the valve 44.

  The dope 13 is manufactured by filtering the cellulose acylate solution 42 with the filtering device 25. The filtration device 25 has a metal filter. By passing the cellulose acylate solution 42 through the metal filter, foreign substances such as additives having a large particle diameter, cellulose acylate, and impurities existing therein are removed. be able to. With respect to the metal filter, the material and pore diameter are not particularly limited, but the average pore diameter is preferably 100 μm or less, and the filtration flow rate during filtration is preferably 50 L / hour.

  The manufactured dope 13 is sent to the stock tank 26 by adjusting the valve 45. The stock tank 26 has a stirring blade 47 interlocked with a motor 46. By rotating the stirring blade 47, the dope 13 is stirred to maintain a state in which various materials are uniformly mixed. The dope 13 is cast to the casting step 14 to produce a cellulose acylate film. The cellulose acylate solution 42 and the dope 13 are preferably defoamed. In this defoaming method, any known method can be applied, and the place of implementation is not particularly limited.

  FIG. 3 shows a film production line 50. The film production line 50 includes a casting chamber 51, a peeling roller 52, a crossing portion 53, a tenter 54, a drying chamber 55, a winding chamber 56, and the like. However, the present invention is not limited to the form shown in FIG.

The casting chamber 51 in which the casting process 14 is performed includes a casting die 60, a pair of rotating rollers 61 and 62, a casting band 63, a heat transfer medium circulation device 64, a temperature control device 65, a recovery device 66, and a decompression chamber. 67, an air supply duct 68, and an exhaust duct 69. The dope 13 is cast from a casting die 60 onto a casting band 63 that runs continuously and endlessly while being supported by rotating rollers 61 and 62. The casting die 60 is preferably made of a two-layer stainless steel, and preferably has a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less. The finishing accuracy of the wetted surface is 1 μm or less in terms of surface roughness, the straightness is 1 μm / m or less in any direction, and the slit clearance is 0.5 mm to 3.5 mm by automatic adjustment. It is preferable to use one that can be adjusted within the range described above. When such a casting die 60 is used, a film having excellent flatness can be obtained. The corner portion R of the liquid contact portion at the tip of the lip of the casting die 60 is 50 μm or less over the entire width of the slit. In addition, it is preferable to use what was adjusted so that the shear rate in the casting die 60 may be 1 (1 / second) or more and 5000 (1 / second) or less.

  The width of the casting die 60 is not particularly limited, but is preferably about 1.0 to 2.0 times the film width as the final product. Moreover, the shape is preferably a coat hanger type, and it is more preferable to provide a thickness adjusting bolt (heat bolt) at a predetermined interval and attach an automatic thickness adjusting mechanism using a heat bolt. The heat bolt is preferably manufactured by setting a profile according to a liquid feeding amount of a pump (for example, a high precision gear pump) according to a program set in advance, but a thickness meter (for example, for example, in the film manufacturing line 50) An infrared thickness gauge) may be provided, and feedback control may be performed by an adjustment program based on the profile. The thickness difference between any two points excluding the casting edge is preferably adjusted to within 1 μm, the largest difference in the minimum thickness in the width direction is adjusted to 3 μm or less, and the thickness accuracy is preferably adjusted to ± 1.5 μm or less. .

It is more preferable that a cured film is formed at the lip end of the casting die 60. The method for forming the cured film is not particularly limited, and methods such as ceramic coating, hard chrome plating, and nitriding treatment may be used. However, when ceramic is used as the cured film, it is excellent in machinability and corrosion resistance, has a low porosity, is not brittle, has good adhesion with the casting die 71, and has poor adhesion with the dope 13. Is preferred. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like, but it is particularly preferable to use WC. The WC coating can be performed by a thermal spraying method.

  A solvent supply device (not shown) is preferably attached to the slit end of the casting die 60 in order to prevent the cast dope 13 from locally drying and solidifying. More preferably, a solvent that solubilizes the dope 13 (for example, a mixed solvent of 86.5 parts by mass of dichloromethane, 13 parts by mass of acetone, and 0.5 parts by mass of n-butanol) is a gas-liquid solution at the end of the casting bead and the slit. To supply the interface. At this time, it is preferable to use a pump having a pulsation rate of 5% or less.

  The casting band 63 is stretched over rotating rollers 61 and 62 provided downstream of the casting die 60, and travels endlessly when the rotating rollers 61 and 62 are rotated by a driving device (not shown). . The moving speed of the casting band 63, that is, the casting speed is preferably 10 m / min or more and 200 m / min or less. A heat transfer medium flow path (not shown) is formed inside the rotation rollers 61 and 62, and the heat transfer medium maintained at a predetermined temperature passes through the heat transfer medium flow path (not shown). Hold at a predetermined temperature. In addition, a heat transfer medium circulation device 64 is attached to the rotating rollers 61 and 62, thereby adjusting the surface temperature of the casting band 63 to a predetermined value. At this time, the surface temperature of the casting band 63 is preferably −20 ° C. or higher and 40 ° C. or lower.

  The shape and material of the casting band 63 are not particularly limited, but the width should be in the range of 1.1 to 3.0 times the casting width of the dope 13. Preferably, the length is 10 m or more and 200 m or less, the thickness is 0.3 mm or more and 10 mm or less, and the surface is polished so that the surface roughness is 0.05 μm or less. More preferably, the material is stainless steel and is made of SUS316 so as to have sufficient corrosion resistance and strength. Further, it is preferable to use a non-uniform thickness of the entire casting band 63 of 0.5% or less.

The tension generated in the casting band 63 when the rotating rollers 61 and 62 are driven is preferably adjusted to be 1.5 × 10 ⁴ kg / m. Further, the relative speed difference between the rotary rollers 61 and 62 and the casting band 63 is adjusted to be 0.01 m / min or less. The speed variation of the casting band 63 is preferably 0.5% or less, and the meandering in the width direction when the casting band 63 rotates once is preferably 1.5 mm or less. In order to control this meandering, it is more preferable to provide a detector (not shown) for detecting both ends of the casting band 63 and perform feedback control based on the measured value. Furthermore, it is preferable to adjust the vertical position fluctuation accompanying the rotation of the rotary roller 61 directly below the casting die 60 to 200 μm or less.

The rotating rollers 61 and 62 can also be used directly as a support. At this time, it is preferable to rotate with high accuracy so that the rotation unevenness is 0.2% or less, and the average roughness of the surfaces of the rotary rollers 61 and 62 to be used is 0.01 μm or less. Therefore, chrome plating is performed to provide sufficient hardness and durability. It should be noted that surface defects of the support (rotating rollers 61 and 62 and casting band 63) must be minimized. Specifically, it is preferable that there are no pinholes of 30 μm or more, pinholes of 10 μm or more and less than 30 μm are 1 / m ² or less, and pinholes of less than 10 μm are 2 / m ² or less.

  The casting chamber 51 is provided with a temperature control facility 65, thereby maintaining the internal temperature at a predetermined value. The internal temperature of the casting chamber 51 is preferably -10 ° C or higher and 57 ° C or lower. In addition, a condenser (condenser) 68 is provided to condense and recover the organic solvent that volatilizes from the casting film 15 and floats inside the casting chamber 51. The condensed and liquefied organic solvent is condensed by the condenser 68, recovered by the recovery device 66, regenerated as a dope preparation solvent, and reused. In this way, when the recovered solvent is used as the dope adjusting solvent, the raw material cost can be reduced, and as a result, the production cost can be reduced.

  The dope 13 cast from the casting die 60 forms the casting film 15 on the casting band 63. The temperature of the dope 13 at the time of casting is preferably −10 ° C. or more and 57 ° C. or less. Further, it is preferable that the decompression chamber 67 is provided in the vicinity of the back surface of the dope 13 to be cast and cast while adjusting to a desired pressure. The decompression chamber 67 is not particularly limited, but preferably includes a jacket (not shown) for maintaining a predetermined temperature, and the temperature is maintained in a range of 10 ° C. or more and 50 ° C. or less. It is preferable.

  The casting film 15 moves as the casting band 63 travels. At this time, in order to evaporate the solvent in the casting film 15, it is preferable to provide a blower duct (not shown). Although the attachment position of the said air duct is not specifically limited, For example, what is necessary is just to provide in the upper upstream of the casting band 63, a downstream, and a lower part. In addition, it is preferable to provide a wind shielding device (not shown) in order to suppress the surface variation of the film surface caused by blowing dry air to the cast film 15 immediately after formation. In FIG. 3, the casting band 63 is used as a support for the casting film 15. However, the present invention is not limited to this form, and for example, a casting drum can be used. At this time, the surface temperature of the casting drum is preferably -20 ° C or higher and 40 ° C or lower.

  After the casting film 15 has self-supporting properties, as the peeling process 14, the casting film 15 is continuously peeled off from the casting band 63 by the peeling roller 52 to form the wet film 17. To do. The stripping roller 52 is a driving roller. The wet film 17 is transported to the transfer section 53 provided with a large number of rollers and then fed into the tenter 54.

  FIG. 4 shows an enlarged view of the crossover part 53. The crossover part 53 includes a plurality of pass rollers 91 to 97 and a blower 100. While the wet film 17 is transported while being supported by the pass rollers 91 to 97, the drying air is blown from the blower 100 to dry it. Each of the pass rollers 91 to 97 is a driving roller, and the temperature of the drying air is preferably 20 ° C. or higher and 250 ° C. or lower. Each pass roller 91 to 97 may be a non-driving roller. Further, in the crossing portion 53, it is possible to give the wet film 17 a draw by making the rotational speed of the downstream pass roller faster than the rotational speed of the upstream pass roller. In this description, the first, second to seventh pass rollers 91 to 97 will be referred to in order from the side closer to the peeling roller 52, that is, from the upstream side of the film production line 50. In the present embodiment, the form in which the seven pass rollers 91 to 97 are arranged is shown, but the number of the pass rollers and the arranged form are not particularly limited. However, the number of pass rollers is preferably 2 or more and 20 or less. If the number of pass rollers is less than 2, the drying time and the conveying distance are too short, so that the ability to dry the wet film 17 is lacking. On the other hand, when there are more than 20, the size of the equipment needs to be increased, resulting in problems such as increased equipment costs and difficulty in securing the equipment installation space. As for the form of the pass roller, for example, a plurality of pass rollers arranged in a staggered manner can be mentioned.

  Each of the pass rollers 91 to 97 only has to have a temperature adjustment function individually, and the form thereof is not particularly limited. The temperature adjusting function may be provided independently for each of the pass rollers 91 to 97, or the temperature is controlled by one temperature adjuster (not shown) connected to each of the pass rollers 91 to 97. May be. For example, the surface temperature of each of the pass rollers 91 to 97 may be adjusted by forming a flow path inside each of the pass rollers 91 to 97 and flowing a heat transfer medium (for example, water) whose temperature is adjusted in the flow path. . Each pass roller 91 to 97 is adjusted to a predetermined temperature and conveyed while supporting the wet film 17. Thus, if it conveys with each pass roller 91-97 which has a temperature adjustment function, stabilization in the transfer part 53 can be aimed at. In other words, since the wet film 17 can be dried without being subjected to unnecessary stress while being dried, the wet film 17 can be dried while suppressing the occurrence of wrinkles and twists on the surface of the wet film 17. it can.

  The temperature of each pass roller 91 to 97 is preferably adjusted to Tm (° C.) or more and Tm + 50 (° C.) or less, more preferably Tm (° C.) when the melting point of the additive used in the dope 13 is Tm (° C.). Tm (° C.) to Tm + 30 (° C.), particularly preferably Tm (° C.) to Tm + 20 (° C.). However, when a plurality of the additives are used in the dope 13, the melting point of the additive having the lowest temperature among these additives is defined as an apparent melting point Tm (° C.). When the temperature is lower than Tm (° C.), when the additive gas comes into contact with the surface of each of the pass rollers 91 to 97, it adheres or accumulates, causing a surface defect of the film. On the other hand, if the temperature is adjusted to a temperature higher than Tm + 50 (° C.), the temperature is too high, so that the polymer in the film is decomposed or deteriorated. Moreover, since the additive etc. to contain volatilize excessively, sufficient function cannot be expressed. However, it is not necessary to unify the temperatures of the pass rollers 91 to 97, and any temperature may be used as long as it is equal to or higher than the melting point of the additive used. For example, when TPP is used as a plasticizer, since the melting point of the TPP is 50 ° C., the temperature of each of the pass rollers 91 to 97 may be adjusted to be 50 ° C. or more and 100 ° C. or less and dried. .

  In the tenter 54, the both sides of the wet film 17 are transported while being gripped by a gripping member such as a clip, and the solvent is volatilized and dried. It is preferable that the tenter 54 is provided with compartments having different temperatures and dried while adjusting the drying conditions. At this time, the wet film 17 may be stretched in the width direction in the tenter 54. In this case, it is preferable that at the transition portion 53 and / or the tenter 54, at least one direction of the wet film 17 in the casting direction and the width direction is stretched by 0.5% or more and 300% or less. When the wet film 17 is stretched as described above, it is preferably relaxed thereafter. At this time, stretching and relaxation are performed by adjusting the gripping tension of the gripping member that grips both ends of the film. The width of the film when gripping both ends of the film is L1 (mm), 1 <(L2-L3) when the film width when stretched to the maximum in the direction is L2 (mm) and the film width when the film is relaxed and the gripping member releases the film is L3 (mm) It is preferable that / L1 × 100 <15.

  In the tenter 54, it is preferable to keep the heating temperature substantially constant at least while the width of the wet film 17 is displaced. “Substantially constant” means that the fluctuation range is within ± 1 ° C. with respect to the target temperature. Thus, when the heating temperature is made substantially constant while the width of the wet film 17 is displaced, the occurrence of planar defects such as wrinkles and wrinkles on the surface of the wet film 17 can be suppressed. In addition, it is preferable that the said heating temperature is hold | maintained at the substantially same temperature in the range of 50 to 180 degreeC.

  After the wet film 17 is dried to a predetermined residual solvent amount in the tenter 54, it is sent out to the drying chamber 55 as a film 19. An ear clip device 80 is provided between the tenter 54 and the drying chamber 55 to cut both ends of the film 19. Both ends of the cut film are sent to a crusher 81 by a cutter blower (not shown), where they are crushed into chips. This chip can be reused for dope preparation, and the production cost can be reduced. In addition, although the process of cutting the both edges of this film can be omitted, it is preferably performed in any one of the casting process 14 to the winding process.

  The drying chamber 55 is provided with a number of rollers 82. While the film 19 is conveyed while being supported by the roller 82, the solvent is volatilized and dried. Although the temperature in the drying chamber 55 is not specifically limited, It is preferable that it is the range of 50 to 180 degreeC. In addition, an adsorption recovery device 83 is attached to the drying chamber 55, and thereby the volatile solvent is adsorbed and recovered. The air from which the solvent component has been removed is blown into the drying chamber 55 as dry air again. The drying chamber 55 is more preferably divided into a plurality of sections in order to change the drying temperature. In addition, it is preferable to perform a preliminary drying of the film 19 by providing a preliminary drying chamber (not shown) between the ear clip device 80 and the drying chamber 55. Thus, when the film 19 is sent into the preliminary drying chamber, a rapid increase in the film temperature can be suppressed, so that a change in the shape of the film can be prevented.

  The dried film 19 is conveyed to the cooling chamber 84 and cooled to approximately room temperature. A humidity control chamber (not shown) may be provided between the drying chamber 55 and the cooling chamber 84. By blowing air adjusted to a desired humidity and temperature to the film 19 in the humidity control chamber, curling on the film 19 and occurrence of winding failure during winding can be suppressed. it can.

  A forced static eliminator (static neutralization bar) 85 is provided downstream of the cooling chamber 84 so that the charged voltage during the conveyance of the film 19 is within a predetermined range (for example, −3 kV to +3 kV). However, the installation location of this forced static elimination apparatus 85 is not limited to this embodiment. Further, it is preferable to provide a knurling roller 86 and emboss the both edges of the film 19 to give the knurling. In addition, it is preferable that the unevenness | corrugation of the knurled location is 1 micrometer or more and 200 micrometers or less.

  The film 19 is fed into the take-up chamber 56 and continuously taken up by a take-up roller 87 provided therein. At this time, it is preferable to wind with the press roller 88 while applying a desired tension. More preferably, the tension is gradually changed from the start to the end of winding. The film 19 to be wound is at least 100 m in the longitudinal direction (casting direction) and the width direction is preferably 600 mm or more, more preferably 1400 mm or more and 1800 mm or less. However, it is also effective when it is larger than 1800 mm.

  In addition, about the raw material in the solution film forming method which obtains a cellulose acylate film, the raw material, the dissolution method and addition method of an additive, the filtration method, and the manufacturing methods of dope, such as defoaming, [0517] of JP, 2005-104148, A It is described in detail from paragraph to [0616] paragraph. These descriptions can be applied to the present invention.

  From casting die, support structure, co-casting, peeling method, stretching, drying conditions for each process, handling method, curl, winding method after flatness correction, solvent recovery method, film recovery method, etc. This is described in detail in paragraphs [0617] to [0889] of Kai 2005-104148. These descriptions can be applied to the present invention.

[Performance / Measurement method]
(Curl degree / thickness)
The performance of the wound cellulose acylate film and the measuring method thereof are described in paragraphs [0112] to [0139] of JP-A-2005-104148. These descriptions can be applied to the present invention.

[surface treatment]
It is preferable that at least one surface of the cellulose acylate film is surface-treated. The surface treatment is preferably at least one of vacuum glow discharge treatment, atmospheric pressure plasma discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, flame treatment, acid treatment or alkali treatment.

[Functional layer]
(Antistatic, hardened layer, antireflection, easy adhesion, antiglare)
At least one surface of the cellulose acylate film may be undercoated. Furthermore, it is preferable to use this cellulose acylate film as a base film as a functional material provided with other functional layers. The functional layer is preferably provided with at least one layer selected from an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer and an optical compensation layer.

The functional layer preferably contains 0.1 mg / m ² or more and 1000 mg / m ² or less of at least one surfactant. Further, the functional layers preferably contain at least one sort of plasticizers in the 0.1 mg / ^{m 2} or more 1000 mg / ^{m 2} or less. Furthermore, it is preferable that the functional layer contains at least one kind of matting agent in a range of 0.1 mg / m ^{2 to} 1000 mg / m ² . Furthermore, it is preferable that the functional layer contains 1 mg / m ² or more and 1000 mg / m ² or less of at least one antistatic agent.

  A method for imparting a surface-treated functional layer to a cellulose acylate film in order to realize various functions and properties is described in detail in paragraphs [0890] to [1087] of JP-A-2005-104148. It is included. These descriptions can be applied to the present invention.

(Use)
The cellulose acylate film is particularly useful as a polarizing plate protective film. Usually, two polarizing plates each having a cellulose acylate film bonded to a polarizer are bonded to a liquid crystal layer to produce a liquid crystal display device. However, the arrangement of the liquid crystal layer and the polarizing plate is not limited, and various known arrangements may be used. Japanese Patent Application Laid-Open No. 2005-104148 describes in detail TN type, STN type, VA type, OCB type, reflective type, and other examples of liquid crystal display devices. This description can be applied to the present invention. The application also describes an optically anisotropic layer and a cellulose acylate film provided with antireflection and antiglare functions. Furthermore, a use as an optical compensation film having a biaxial cellulose acylate film imparted with appropriate optical performance is also described. This can also be used as a polarizing plate protective film. Details are described in paragraphs [1088] to [1265] of JP-A-2005-104148. These descriptions can be applied to the present invention.

  Moreover, it is preferable that the axis | shaft deviation of the slow axis in the arbitrary area | regions of the manufactured film and the slow axis of all the area | regions adjacent to this arbitrary area | region is less than 2.0 degree | times. In addition, it is more preferable that the axial deviation is less than 1.0 degree. Furthermore, the present invention can also be applied when manufacturing a thin film having a film thickness of 15 μm or more and 100 μm or less.

  Moreover, the cellulose triacetate film (TAC film) which is excellent in an optical characteristic by this invention can be obtained. The TAC film can be used as a polarizing plate protective film or a base film of a photographic photosensitive material. Furthermore, it can also be used as an optical compensation film for improving the viewing angle dependency of a liquid crystal display device for television applications. In particular, it is effective for applications that also serve as a protective film for a polarizing plate. Therefore, it is used not only for the conventional TN mode but also for the IPS mode, OCB mode, VA mode, and the like. In addition, you may comprise a polarizing plate using the said film for polarizing plate protective films.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples. For the examples other than Example 1 and the comparative example, the description of the same conditions as in Example 1 is omitted.

In order to produce a cellulose acylate film, a dope 13 was produced by a dope production line 20 shown in FIG.
Cellulose triacetate: 20 parts by weight, methyl acetate: 58 parts by weight, acetone: 5 parts by weight, methanol: 5 parts by weight, ethanol: 5 parts by weight, butanol: 5 parts by weight, UV agent a (2,4-bis- (n -Octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine): 0.2 parts by weight, UV agent b (2 (2'-hydroxy-3 ' , 5'-di-tert-butylphenyl) -5-chlorobenzotriazole): 0.2 parts by weight, UV agent c (2 (2'-hydroxy-3 ', 5'-di-tert-amylphenyl)- 5-chlorobenzotriazole): 0.2 part by weight, release agent a (C ₁₂ H ₂₅ OCH ₂ CH ₂ O—P (═O) — (OK) ₂ ): 0.02 part by weight, release agent b (quenched) Acid): 0.02 parts by weight, Fine particles (silicon dioxide (particle size 20 nm, Mohs hardness about 7)): 0.05 parts by weight, and a desired amount of plasticizer and retardation control agent are appropriately fed into the dissolution tank 24 and mixed thoroughly. After the cellulose acylate solution 42 was prepared by heating with the heating device 41, the cellulose acylate solution 42 was filtered with the filtration device 25 to obtain a dope 13. In addition, the addition amount of a plasticizer and a retardation control agent is mentioned later.

  The film 19 was manufactured using the film manufacturing line 50 shown in FIG. The dope 13 was cast on the casting band 63 running from the casting die 60. The casting die 60 was kept at 36 ° C., was of a coat hanger type, and had thickness adjusting bolts provided at a pitch of 20 mm. After the casting film 15 was formed on the casting band 63, it was peeled off by the peeling roller 52 to produce the wet film 17. The wet film 17 was fed into the transfer section 53 shown in FIG. 4, and then dried while being blown from the blower 100 while being transported while being supported by the pass rollers 91 to 97. The temperature conditions of the pass rollers 91 to 97 will be described later. After the transfer part 53, the wet film 17 was sent to the tenter 54 and further dried. In the tenter 54, the internal temperature was 140 ° C., the two side ends of the wet film 17 were held with clips, and a 20 kg / m tension was applied in the width direction, and the film 19 was dried. The film 19 was fed into the drying chamber 55 and was sufficiently dried while being conveyed while being supported by the rollers 82. The dried film 19 was cooled to room temperature in the cooling chamber 84 and then taken up by the take-up roller 87 in the take-up chamber 56.

  In Example 1, a retardation control agent (additive A) and a plasticizer (additive B) were used as additives constituting the dope 13. The amount of additive A and additive B added (ratio when the cellulose acylate was 100 parts by weight; PHR) was 4.2 PHR and 10.7 PHR, respectively. In this case, the melting points of the additive A and the additive B are −12 ° C. and 50 ° C., respectively. Therefore, among the pass rollers 91 to 97 in the crossing section 53, the temperatures of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 are set to 60 ° C., 65 ° C., 67 ° C., and 70 ° C., respectively. The wet film 17 was dried by adjusting the temperature to 100 ° C. and adjusting all the pass rollers other than the above to 100 ° C. Hereinafter, the temperature of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 will be collectively referred to as pass roller conditions. In any of the examples / comparative examples to be described later, as the pass roller conditions, the temperature of only the first, third, fourth, and sixth pass rollers is changed (the temperatures of the other pass rollers are constant). Manufactured.

  A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, the film 19 was produced with the same amounts of additive A and additive B as those of Example 1 and 4.2 PHR and 11.7 PHR, respectively.

  A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, the amount of each additive is the same as in Example 1, but as the pass roller conditions, the temperatures of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 are 67 ° C., 67 ° C., and 70 ° C., respectively. And 70 ° C.

  A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, while the pass roller conditions were the same as in Example 1, the amounts of additive A and additive B were 4.2 PHR and 11.7 PHR, respectively.

  A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, while the pass roller conditions were the same as in Example 1, the amounts of additive A and additive B were 5.1 PHR and 10.7 PHR, respectively.

  A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, while the pass roller conditions at the crossover portion 53 were the same as in Example 1, the amounts of additive A and additive B were 5.1 PHR and 11.7 PHR, respectively.

  A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, with respect to Example 1, as the pass roller conditions, the temperatures of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 were 67 ° C., 67 ° C., 70 ° C., and 70 ° C., respectively. . Moreover, the addition amount of the additive A and the additive B was set to 5.1 PHR and 10.7 PHR, respectively.

  A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, with respect to Example 1, as the pass roller conditions, the temperatures of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 were 67 ° C., 67 ° C., 70 ° C., and 70 ° C., respectively. . Moreover, the addition amount of the additive A and the additive B was set to 5.1 PHR and 11.7 PHR, respectively.

[Comparative Example 1]
A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, the temperature of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 was set to 30 ° C., 35 ° C., 40 ° C., and 45 ° C., respectively, as the pass roller conditions for Example 1. . Moreover, the addition amount of the additive A and the additive B was 4.2 PHR and 10.7 PHR, respectively.

[Comparative Example 2]
A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, the temperature of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 was set to 30 ° C., 35 ° C., 40 ° C., and 45 ° C., respectively, as the pass roller conditions for Example 1. . The addition amounts of Additive A and Additive B were 4.2 PHR and 11.7 PHR, respectively.

[Comparative Example 3]
A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, the temperature of the first pass roller 91, the third pass roller 93, the fourth pass roller 94, and the sixth pass roller 96 was set to 30 ° C., 35 ° C., 40 ° C., and 45 ° C., respectively, as the pass roller conditions for Example 1. . Moreover, the addition amount of the additive A and the additive B was set to 5.1 PHR and 10.7 PHR, respectively.

[Comparative Example 4]
A cellulose acylate film was produced using the same raw materials and production conditions as in Example 1. However, although the amount of each additive was the same as in Example 1, the film was manufactured without heating any of the pass rollers 91 to 97 in the crossover part 53.

The composition of the dope 13 of Example 1 was changed to the following.
[composition]
Cellulose triacetate (TAC) 100 parts by weight (acetyl group substitution degree 2.81 (acetylation degree 60.2%), Mw / Mn = 2.7, viscosity average polymerization degree 305, viscosity of 6% by mass in dichloromethane solution 350 mPa · s)
-Dichloromethane (first solvent) 430 parts by weight-Methanol (second solvent) 48 parts by weight-Plasticizer A 7.6 parts by weight-Plasticizer B 3.8 parts by weight The above plasticizer A is triphenyl phosphate ( TPP), plasticizer B is biphenyl diphenyl phosphate (BDP).

  An additive solution C was prepared with the retardation control agent shown in Chemical Formula 1, a part of the dope 13 and a solvent of dichloromethane: methanol = 9: 1 (mass ratio) and filtered.

  Further, an additive liquid D was prepared by mixing fine particles (trade name: Aerosil R972, Nippon Aerosil Co., Ltd.), a part of the dope 13 and a solvent of dichloromethane: methanol = 9: 1 (mass ratio). . In the additive liquid D, the following fine particles were dispersed by an attritor so that the volume average particle diameter was 0.7 μm. The additive liquid D after dispersion was filtered.

  The additive liquid D was mixed with the additive liquid C using an in-line mixer, and this mixed liquid was mixed with the dope 13 using an in-line mixer. In this way, a liquid having a matting agent of 1% by weight and a retardation control agent of 6% by weight was obtained for casting when the film 19 was prepared. Other conditions are the same as those in the first embodiment.

  The implementation conditions and results of this example are shown in Table 1. In the table, the temperature of the first pass roller 91 is temperature A, the third pass roller 93 is temperature B, the fourth pass roller 94 is temperature C, and the sixth pass roller 96 is temperature D.

[Evaluation method of effect in the present invention]
In the present invention, the surface of the produced film was visually observed to check for the presence of a roller transfer defect and a push flaw defect (hereinafter, both are collectively referred to as a defect). At this time, regarding the roller transfer defect, depending on the amount of deposits attached to the film surface, ◎, which is almost nonexistent, ○, which is very small, △ which is somewhat present but has no problem in film characteristics Evaluation was made as x for those having problems in characteristics. Further, regarding the scratch defect, the evaluation was evaluated as “O” for very few defects, “Δ” for the presence of defects but not causing problems in characteristics, and “X” for problems causing problems in characteristics.

  As is apparent from Table 1, in order to examine the temperature adjustment effect of each of the pass rollers 91 to 97 heated in the crossing part 53, in Examples 1 to 8, all the temperatures are 60 ° C. or higher than the melting point of the additive. In contrast, all of Comparative Examples 1 to 3 were adjusted to a temperature of 45 ° C. or lower. Moreover, in the comparative example 4, only the air supply from the air blower 100 was performed, without heating each pass roller 91-97 (no temperature adjustment), and the film 19 was manufactured, respectively. As a result, with respect to the degree of defects, in Examples 1 to 8, although there was a slight difference, there was no problem in characteristics (◯ or ◎), whereas in Comparative Examples 1 to 3, all of the characteristics were high. The defect which became a problem was confirmed (x). In Comparative Example 4, which is a conventional method, there was no problem in characteristics, but some defects were confirmed (Δ).

[Influence of pass roller temperature]
When the temperatures of the pass rollers 91 to 97 were heated to the melting point Tm (° C.) or more (60 ° C. or more in the present embodiment) of the additive used for the dope 13 (Example 1 to Example 8), defects were found. It was confirmed that it was possible to produce a film having excellent characteristics without the occurrence. At this time, it was confirmed that not only the influence on the defect but also the conveyance at the crossing portion 53 can be stabilized. Such a tendency is shown in Example 1, Example 3, and Comparative Example 1 (the above three are collectively referred to as Group A), or Example 2, Example 4, and Comparative Example 2 (the above three are summarized). The group B) was clearly confirmed. That is, in Group A, in Example 3, where the average heating temperature under the pass roller condition is the highest, roll transfer defects are ◎, whereas in Example 1, where the temperature is slightly lower, Δ, and both are Comparative Examples 1 at 45 ° C. or lower. It was x. The same tendency was observed in Group B, which averaged more additive than Group A. As described above, in the crossover portion 53, when the film is dried while being supported by the temperature-adjusted pass rollers 91 to 97, defects on the surface thereof are reduced, and the film is manufactured while stabilizing the conveyance. I found out that In addition, when the heating temperature was more than melting | fusing point Tm (degreeC) of the additive to be used, it confirmed that it was especially effective.

The flow of the manufacturing process of the cellulose acylate film in this invention is shown. The schematic of the dope production line in this invention is shown. The schematic of the film production line in this invention is shown. The enlarged view of the transition part in the film manufacturing line in this invention is shown.

Explanation of symbols

13 Dope 15 Casting film 17 Wet film 19 Film 20 Dope production line 42 Cellulose acylate solution 50 Film production line 54 Tenta 55 Drying chamber 91 First pass roller 92 Second pass roller 93 Third pass roller 94 Fourth pass roller 95 Fifth pass roller 96 6th pass roller 97 7th pass roller

Claims (5)

A polymer solution in which a polymer, a solvent, and an additive are mixed is cast on a running support to form a cast film, and the cast film is continuously peeled off from the support to form a solvent-containing film. From the method for producing a polymer film having a first drying step of drying the film containing the solvent,
In the first drying step, by a plurality of pass rollers each having a temperature adjustment function,
A method of producing a polymer film, wherein the film is dried while the film containing the solvent is conveyed while adjusting a surface temperature of the pass roller. When the melting point of the additive is Tm (° C.)
The method for producing a polymer film according to claim 1, wherein the surface temperature of the pass roller is Tm (° C.) or higher and Tm + 50 ° C. or lower. Performing a second drying step after the first drying step;
In the second drying step, while transporting while holding the both side ends of the solvent-containing film by a gripping member, the film is dried by a drying facility,
3. The method for producing a polymer film according to claim 1, wherein the heating temperature of the film is substantially constant at least while the width of the film is displaced.   The method for producing a polymer film according to any one of claims 1 to 3, wherein the polymer is cellulose acylate.   A polymer film produced using the method according to any one of claims 1 to 4.

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