JP2006259151A - Manufacturing method and device of optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To greatly reduce surface defects caused by defective alignment in the manufacturing of an optical film, especially in the manufacturing of an optical compensating film. <P>SOLUTION: In the manufacturing method of the optical film, a belt shaped and flexible support body 16 is continuously run, a rubbing process is conducted for the surface of the support body by a rubbing device 70, and coating liquid is applied onto the surface of the support body by a coating means 11, after the rubbing process so as to form a functional film. A support body temperature adjusting means is arranged in the upper stream side of the rubbing device for controlling the moisture content of the support body, and the rubbing device is covered by a rubbing moisture adjusting means to control atmospheric humidity of the surrounding of the rubbing device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical film manufacturing method and apparatus, and more particularly, to an optical film manufacturing method and apparatus suitable for obtaining an optical compensation film with greatly reduced surface defects.

  In recent years, the demand for optical films is increasing. Typical examples of the optical film include films having various functions such as an optical compensation film used as a retardation plate in a liquid crystal cell, an antireflection film, and an antiglare film.

  As a representative method for producing such an optical film, the surface of a belt-like flexible support (hereinafter referred to as “web”) is subjected to rubbing treatment, and then various coating devices are used on the surface of the web. Then, a coating solution is applied, dried, and then cured to form coating films (functional films) having various compositions.

  In the production of such an optical film, orientation failure due to unstable rubbing treatment conditions has become a problem as one factor of yield reduction. Conventionally, various proposals have been made to reduce such orientation defects (see Patent Documents 1 and 2).

  The proposal of Patent Document 1 is configured to reduce scratches on the alignment film by controlling the moisture content of the rubbing cloth and controlling the atmospheric humidity during rubbing to a predetermined range.

The proposal of patent document 2 is a structure which reduces the orientation defect by providing a blower, blowing the temperature-controlled and humidity-controlled air on the surface of the web before rubbing, and controlling the water content of the web. is there.
Japanese Patent Laid-Open No. 11-271776 JP 2003-329833 A

  However, even with the configurations of Patent Documents 1 and 2 and the like, the alignment failure is not greatly reduced, and the alignment failure still remains a problem as one factor of yield reduction.

  The present invention has been made in view of such circumstances, and in the manufacture of an optical film, in particular, in the manufacture of an optical compensation film, the manufacture of an optical film capable of greatly reducing surface defects caused by poor alignment. It is an object to provide a method and apparatus.

  In order to achieve the above-mentioned object, the present invention applies a rubbing treatment to the surface of the support by a rubbing device while continuously running the belt-like flexible support and applies the rubbing treatment to the surface of the support after the rubbing treatment. In the method of manufacturing an optical film in which a functional film is formed by applying a coating liquid by means, a support humidity adjusting means is provided on the upstream side of the rubbing device to control the water content of the support, and the rubbing An optical film manufacturing method is provided, wherein the apparatus is covered with a rubbing humidity adjusting means to control the atmospheric humidity around the rubbing apparatus.

  For this purpose, the present invention is provided with a support running means for continuously running a belt-like flexible support, a rubbing device for rubbing the surface of the support, and an upstream side of the rubbing device. A support humidity adjusting means for controlling the moisture content of the support, a rubbing humidity adjusting means for covering the rubbing apparatus to control the atmospheric humidity around the rubbing apparatus, and a surface of the support after the rubbing treatment. An optical film manufacturing apparatus comprising: an application unit that applies a coating liquid.

  According to the present invention, in the production of the optical film, the support humidity adjusting means is provided on the upstream side of the rubbing device, the moisture content of the support is controlled, and the rubbing device is covered with the rubbing humidity adjusting means to surround the rubbing device. Since the atmospheric humidity is controlled, the alignment film on the web surface can be controlled to an optimum state during the rubbing treatment, and the surface defects caused by the alignment failure can be greatly reduced.

  That is, the present inventor, unlike each configuration of the conventional examples (Patent Documents 1 and 2, etc.), controls the water content of the support and controls the atmospheric humidity around the rubbing device, thereby controlling the web surface during the rubbing process. It was found that the alignment film can be controlled to an optimum state. Thereby, in the manufacture of an optical film, particularly in the manufacture of an optical compensation film, it has become possible to significantly reduce surface defects due to poor alignment.

  The optical film includes films having various functions such as an optical compensation film, an antireflection film, and an antiglare film.

  In this invention, it is preferable to control so that the atmospheric humidity of the said support body humidity adjustment means may be below the atmospheric humidity around the said rubbing apparatus. In the present invention, it is preferable that the atmospheric humidity of the support humidity adjusting means is controlled to be 10% or more lower in relative humidity than the atmospheric humidity around the rubbing apparatus.

  In this way, by controlling the atmospheric humidity of the support humidity adjusting means to be equal to or lower than the atmospheric humidity around the rubbing apparatus, the alignment film can be maintained in a state that is not easily damaged, and appropriate moisture is given to the rubbing roller, By increasing the contact area between the roller and the alignment film, the alignment state can be improved.

  In the present invention, the support is preferably a polymer film. In the present invention, the optical film is preferably an optical compensation film. The effect of the present invention can be exerted on such an optical compensation film.

  As described above, according to the present invention, the alignment film on the web surface can be controlled to an optimum state during the rubbing process, and surface defects caused by alignment defects can be greatly reduced.

  Hereinafter, preferred embodiments of an optical film manufacturing method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing an optical film production line to which the method and apparatus for producing an optical film according to the present invention is applied.

  As shown in FIG. 1, the optical film production line 10 is configured to feed a web 16, which is a transparent support having a polymer layer for forming an alignment film formed in advance, from a feeder 66. The web 16 is guided by a guide roller 68 and passes through a humidity control zone 20 which is a support body humidity adjusting means. The humidity control zone 20 will be described later.

  Thereafter, the web 16 is guided by the guide roller 68 and is fed into the rubbing processing device 70. The rubbing roller 72 is provided to perform a rubbing process on the polymer layer. A dust remover 74 is provided downstream of the rubbing roller 72 so that dust adhering to the surface of the web 16 can be removed.

  A gravure coating device 11 is provided downstream of the dust remover 74 so that a coating liquid containing a disconematic liquid crystal can be applied to the web 16. Downstream of this, a drying zone 76 and a heating zone 78 are sequentially provided so that a liquid crystal layer can be formed on the web 16. Further, an ultraviolet lamp 80 is provided downstream of the liquid crystal so that a desired polymer can be formed by crosslinking the liquid crystal by ultraviolet irradiation. And the web 16 in which the polymer was formed is wound up by the winder 82 provided downstream.

  The humidity control zone 20 is composed of an upper cover 20A and a lower cover 20B, and both form a tunnel shape. That is, the web 16 is carried from a slit 20 </ b> C that is formed on the inlet side (right side) of the humidity control zone 20 in the width direction (perpendicular to the paper surface) of the web 16. The web 16 is carried out from a slit 20 </ b> D elongated in the width direction (perpendicular to the paper surface) of the web 16 formed on the outlet side (right side).

  In the humidity control zone 20, air whose temperature and humidity are optimally adjusted is supplied from a humidity control air supply port (not shown). Various known means such as a dehumidifier and a combination of a dehumidifier and an air conditioner (air conditioner) can be adopted as a humidity control air supply means (not shown) for supplying air whose temperature and humidity are optimally adjusted.

  The rubbing apparatus 70 is an apparatus for performing a rubbing process on the polymer layer, and has a one-stage roller configuration with a rubbing roller 72 in this example. Note that a multi-stage roller configuration may be employed as the bing processing device 70. The rubbing treatment device 70 is covered with a rubbing booth 71 that is a rubbing humidity adjusting means so that the atmospheric humidity around the rubbing treatment device 70 can be controlled.

  The rubbing treatment device 70 is configured to rotate a rubbing roller 72 having a rubbing cloth such as velvet wrapped around the outer peripheral surface thereof, and can control the rotational speed to about 1000 rpm, for example. The shape of the rubbing roller 72 may be, for example, a roller having an outer diameter of 150 mm and a length slightly longer than the width of the web 16 even when the rubbing angle is set. Further, the rubbing treatment device 70 can be freely rotated in a horizontal plane with respect to the traveling direction of the web 16 so that the rubbing treatment device 70 can be adjusted to an arbitrary rubbing angle.

  A roller stage 84 is provided above the rubbing roller 72, and backup rollers 86 and 88 are rotatably attached to the lower surface of the roller stage 84 via springs. The backup rollers 86 and 88 are provided with a mechanism for detecting the tension of the web 16 so that the tension during rubbing can be managed.

  Further, the backup rollers 86 and 88 can be adjusted up and down, and the wrap angle of the web 16 to the rubbing roller 72 can be adjusted by moving the rollers up and down.

  With the above configuration, the resin layer on the surface (lower surface) of the web 16 is rubbed by the rubbing roller 72 pressed from the lower side while the web 16 is pressed from above by the backup rollers 86 and 88.

  The rubbing booth 71 that is a rubbing humidity adjusting means covers substantially the entire rubbing processing device 70 and is configured to control the atmospheric humidity around the rubbing processing device 70. That is, only an elongated slit 71A perpendicular to the paper surface is provided as an opening so that only the upper part of the rubbing roller 72 is exposed.

  In the rubbing booth 71, air whose temperature and humidity are optimally adjusted is supplied from a humidity control air supply port (not shown). Various known means such as a dehumidifier and a combination of a dehumidifier and an air conditioner (air conditioner) can be adopted as a humidity control air supply means (not shown) for supplying air whose temperature and humidity are optimally adjusted.

  Next, the downstream configuration of the rubbing processing device 70 will be described.

  As the dust remover 74, various known types can be adopted. For example, a configuration in which compressed air (nitrogen gas) subjected to electrostatic dust removal is sprayed on the surface of the web 16 to remove dust adhering to the surface of the web 16 can be employed.

  The gravure coating device 11 is a device that applies a coating liquid to a web 16 that is guided by an upstream guide roller 17 and a downstream guide roller 18 and that is driven to rotate. The upstream guide roller 17 and the downstream guide roller 18 are arranged so that the web 16 travels while being pressed against the gravure roller 12 with a predetermined pressure.

  The gravure roller 12, the upstream guide roller 17 and the downstream guide roller 18 have substantially the same length as the width of the web 16.

  Among these, it is preferable that the diameter of the gravure roller 12 is 20 to 250 mm. By setting the diameter of the gravure roller 12 in such a range, an effect of suppressing the vibration of the web 16 can be obtained. There is no particular limitation on the diameter of the upstream guide roller 17 and the downstream guide roller 18, but the diameter is preferably 60 mm or more. By setting the diameters of the upstream guide roller 17 and the downstream guide roller 18 in such a range, an effect of suppressing the vibration of the web 16 can be obtained.

  The gravure roller 12 is driven to rotate as indicated by the arrow in FIG. This rotational direction is the reverse direction to the traveling direction of the web 16. In addition, the application | coating by the drive of forward rotation contrary to FIG. 1 can also be employ | adopted depending on application | coating conditions (for example, installation of a doctor blade).

  The driving method of the gravure roller 12 is direct driving (shaft direct connection) by an inverter motor, but a combination of various motors and a reduction gear (gear head), or a method using winding transmission means such as a timing belt from various motors. Good.

  The cell (cell) shape on the surface of the gravure roller 12 may be any of a known pyramid type, lattice type, diagonal line type, and the like. That is, an appropriate cell may be selected depending on the coating speed, the viscosity of the coating solution, the coating film thickness, and the like.

  A liquid receiving pan 14 is provided below the gravure roller 12, and the liquid receiving pan 14 is filled with a coating liquid. The lower half of the gravure roller 12 is immersed in the coating solution. With this configuration, the coating liquid is supplied to the cells on the surface of the gravure roller 12.

  A doctor blade 15 is installed so that the tip of the gravure roller 12 is in contact with the gravure roller 12 at about 10 o'clock in order to scrape off the excess of the coating solution before coating. The doctor blade 15 is urged by an urging means (not shown) in the direction of the arrow in FIG. 1 around the rotation center 15A at the base end.

  Note that the gravure coating apparatus 11 as the coating unit is an example, and other types of coating unit may be employed. As such a coating means, a bar coater, a roll coater (transfer roll coater, reverse roll coater, etc.), a die coater, an extrusion coater, a fountain coater, a curtain coater, a dip coater, a spray coater or a slide hopper can be employed.

  As the drying zone 76 and the heating zone 78 downstream of the gravure coating apparatus 11, any coating layer can be used as long as the coating layer is dried and a liquid crystal layer can be formed on the web 16. For example, as shown in the figure, a tunnel-shaped drying zone 76 and a heating zone 78 may be used, and those provided with drying means and heating means (heater or hot air generator) inside may be employed.

  The ultraviolet lamp 80 may be any lamp that can form a desired polymer by crosslinking the liquid crystal by ultraviolet irradiation.

  A winder 82 provided downstream of the ultraviolet lamp 80 can wind the web 16 on which the polymer is formed.

  In the present embodiment, the entire optical film production line 10, particularly the gravure coating device 11, may be installed in a clean atmosphere such as a clean room. At that time, the cleanliness is preferably class 1000 or less, more preferably class 100 or less, and still more preferably class 10 or less.

  Next, each material constituting the optical film will be described.

  As the web 16 used in the present invention, it is preferable to use a polymer film having a light transmittance of 80% or more. As the polymer film, a film in which birefringence hardly occurs due to external force is preferable. Examples of the polymer include cellulose-based polymers, norbornene-based polymers (for example, Arton (manufactured by JSR Corporation), Zeonore, Zeonex (all manufactured by Nippon Zeon Corporation)), and polymethyl methacrylate. Polymers are preferred, cellulose esters are more preferred, and lower fatty acid esters of cellulose are even more preferred.

  This lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). Cellulose acetate is preferred as the cellulose ester, and examples thereof include diacetyl cellulose and triacetyl cellulose. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used.

  In general, the hydroxyl groups of 2, 3, and 6 of cellulose acetate are not evenly distributed by 1/3 of the total substitution degree, and the substitution degree of the 6-position hydroxyl group tends to be small. In the present invention, it is preferable that the substitution degree of the 6-position hydroxyl group of cellulose acetate is larger than that of the 2- and 3-positions.

  The hydroxyl group at the 6-position with respect to the total substitution degree is preferably substituted with 30% or more and 40% or less acyl group, more preferably 31% or more, and particularly preferably 32% or more. Further, the substitution degree of the 6-position acyl group of cellulose acetate is preferably 0.88 or more.

  The 6-position hydroxyl group may be substituted with a propionyl group, butyroyl group, valeroyl group, benzoyl group, acryloyl group or the like, which is an acyl group having 3 or more carbon atoms, in addition to the acetyl group. The degree of substitution at each position can be determined by NMR.

  As the cellulose acetate of the present invention, Synthesis Example 1 described in Paragraph Nos. 0043 to 0044 of JP-A No. 11-5851, Synthetic Example 2 described in Paragraph Nos. 0048 to 0049, and Paragraph Nos. 0051 to 0052 The cellulose acetate obtained by the synthesis method of Synthesis Example 3 described can be used.

  In order to adjust the retardation of the polymer film, an aromatic compound having at least two aromatic rings is used as a retardation increasing agent.

  When a cellulose acetate film is used as the polymer film, the aromatic compound is used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of cellulose acetate. The aromatic compound is preferably used in the range of 0.05 to 15 parts by mass, and more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of cellulose acetate. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring.

  The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable.

  Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable. More preferred are a benzene ring and a 1,3,5-triazine ring. The aromatic compound particularly preferably has at least one 1,3,5-triazine ring.

  The number of aromatic rings contained in the aromatic compound is preferably 2 to 20, more preferably 2 to 12, still more preferably 2 to 8, and most preferably 2 to 6. . The bonding relationship between two aromatic rings can be classified into (a) when forming a condensed ring, (b) when directly connecting with a single bond, and (c) when connecting via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring of (a) (condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a naphthacene ring, a pyrene ring, Indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline ring, quinolidine Ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thianthrene ring It is. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded with two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed.
c1: -CO-O-
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: -O-alkylene-O-
c8: -CO-alkenylene-
c9: -CO-alkenylene-NH-
c10: -CO-alkenylene-O-
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-c13: -O-CO-alkylene-CO-O-
c14: -NH-CO-alkenylene-
c15: -O-CO-alkenylene-
The aromatic ring and the linking group may have a substituent. Examples of the substituent include halogen atom (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl group, alkenyl group, alkynyl group, aliphatic acyl group , Aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic Substituted sulfamoyl groups, aliphatic substituted ureido groups and non-aromatic heterocyclic groups are included.

  It is preferable that the alkyl group has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent.

  Examples of alkenyl groups include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of alkynyl groups include ethynyl, 1-butynyl and 1-hexynyl.

  The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include acetoxy. The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (eg, alkoxy group).

  Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

  The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include methylthio, ethylthio and octylthio.

  The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include methanesulfonyl and ethanesulfonyl.

  The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide. The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include methanesulfonamido, butanesulfonamido and n-octanesulfonamido. The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino.

  The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include methylureido. Examples of non-aromatic heterocyclic groups include piperidino and morpholino. The molecular weight of the retardation increasing agent is preferably 300 to 800.

  Specific examples of the retardation increasing agent are described in JP-A Nos. 2000-1111914, 2000-275434, PCT / JP00 / 02619.

  Hereinafter, the case where a cellulose acetate film is used as the polymer film will be specifically described. It is preferable to produce a cellulose acetate film by a solvent cast method. In the solvent cast method, a film is produced using a solution (dope) in which cellulose acetate is dissolved in an organic solvent.

  The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain.

  The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.

  Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms of the halogenated hydrocarbon 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%. Methylene chloride is a representative halogenated hydrocarbon.

  Technically, halogenated hydrocarbons such as methylene chloride can be used without problems, but from the viewpoint of the global environment and working environment, the organic solvent preferably does not substantially contain halogenated hydrocarbons. “Substantially free” means that the proportion of halogenated hydrocarbon in the organic solvent is less than 5% by mass (preferably less than 2% by mass). Moreover, it is preferable that halogenated hydrocarbons such as methylene chloride are not detected at all from the produced cellulose acylate film. Two or more organic solvents may be mixed and used.

  A cellulose acetate solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent. The amount of cellulose acetate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass.

  Arbitrary additives described later may be added to the organic solvent (main solvent). The solution can be prepared by stirring cellulose acetate and an organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, cellulose acetate and an organic solvent are placed in a pressure vessel and sealed, and stirred while heating to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C or higher, preferably 60 to 200 ° C, more preferably 80 to 110 ° C.

  Each component may be coarsely mixed in advance and then placed in a container. 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. Each component is dissolved in a solvent in the container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

  Preparation of the cellulose acetate solution (dope) of the present invention is carried out according to a cooling dissolution method and will be described below. First, cellulose acetate is gradually added to an organic solvent with stirring at a temperature around room temperature (-10 to 40 ° C). When a plurality of solvents are used, the order of addition is not particularly limited.

  For example, after adding cellulose acetate to the main solvent, another solvent (for example, a gelling solvent such as alcohol) may be added, or conversely, the main solvent after the gelling solvent is previously moistened in cellulose acetate. A solvent may be added, which is effective in preventing non-uniform dissolution. The amount of cellulose acetate is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.

  The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). When cooled in this way, the mixture of cellulose acetate and organic solvent solidifies. Although the cooling rate is not particularly limited, in the case of batch-type cooling, the viscosity of the cellulose acetate solution increases with cooling, and the cooling efficiency is inferior. is necessary.

  In addition, the cellulose acetate solution of the present invention can be achieved by swelling the cellulose acetate solution and then transferring the cooling device at a predetermined cooling temperature for a short time. The faster the cooling rate, the better. However, 10,000 ° C / second is the theoretical upper limit, 1000 ° C / second is the technical upper limit, and 100 ° C / second is the practical upper limit.

  The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling until the final cooling temperature is reached. Further, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), cellulose acetate flows in the organic solvent. Become a solution. The temperature can be raised by simply leaving it at room temperature or in a warm bath.

  A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution with the naked eye.

  In the cooling dissolution method, it is desirable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, if the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container.

  In addition, according to differential scanning calorimetry (DSC), a 20 mass% solution obtained by dissolving cellulose acetate (acetylation degree: 60.9%, viscosity average polymerization degree: 299) in methyl acetate by a cooling dissolution method was 33. There exists a quasi-phase transition point between the sol state and the gel state in the vicinity of ° C, and a uniform gel state is obtained below this temperature.

  Therefore, this solution needs to be stored at a temperature equal to or higher than the pseudo phase transition temperature, preferably about the gel phase transition temperature plus 10 ° C. However, this pseudo phase transition temperature varies depending on the degree of acetylation of cellulose acetate, the degree of viscosity average polymerization, the concentration of the solution, and the organic solvent used.

  A cellulose acetate film is produced from the prepared cellulose acetate solution (dope) by a solvent cast method. Moreover, it is preferable to add the above-mentioned retardation increasing agent to the dope. The dope is cast on a drum or band and the solvent is evaporated to form a film. The dope before casting is preferably adjusted to have a solid content of 10 to 40%, more preferably 18 to 35%. The surface of the drum or band is preferably finished in a mirror state.

  For casting and drying methods in the solvent casting method, U.S. Pat. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.

  The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band and further dried with high-temperature air whose temperature is changed successively from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

  In the present invention, the obtained cellulose acetate solution may be cast as a single layer liquid on a smooth band or drum as the web 16, or a plurality of cellulose acetate liquids of two or more layers may be cast. Good. When casting a plurality of cellulose acetate solutions, a film may be prepared while casting and laminating a solution containing cellulose acetate from a plurality of casting openings provided at intervals in the traveling direction of the web 16. For example, methods described in JP-A-61-158414, JP-A-1-122419, JP-A-11-198285, etc. can be applied.

  Further, it may be formed into a film by casting a cellulose acetate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in Japanese Utility Model Laid-Open Nos. 61-104413, 61-158413, and 6-134933. Alternatively, a cellulose acetate film casting method in which a flow of a high-viscosity cellulose acetate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acetate solution and the high- and low-viscosity cellulose acetate solution is simultaneously extruded. .

  Alternatively, by using two casting ports, the film cast on the web 16 is peeled off by the first casting port, and the second casting is performed on the side that is in contact with the surface of the web 16 to thereby remove the film. For example, it is a method described in Japanese Patent Publication No. 44-20235. The cellulose acetate solution to be cast may be the same solution or different cellulose acetate solutions, and is not particularly limited. In order to give a function to a plurality of cellulose acetate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port.

  Furthermore, the cellulose acetate solution of the present invention can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer). In conventional single-layer liquids, it is necessary to extrude a high-concentration and high-viscosity cellulose acetate solution to obtain the required film thickness. In this case, the stability of the cellulose acetate solution is poor and solids are generated. In many cases, however, it becomes a problem due to a failure or poor flatness. As a solution to this, by casting a plurality of cellulose acetate solutions from the casting port, a highly viscous solution can be extruded onto the web 16 at the same time, and the planarity is improved and an excellent planar film can be produced. In addition, by using a concentrated cellulose acetate solution, it was possible to reduce the drying load and increase the film production speed.

  A plasticizer can be added to the cellulose acetate film in order to improve mechanical properties or increase the drying speed. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters.

  Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB).

  Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of the cellulose ester, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

  Degradation inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines) may be added to the cellulose acetate film. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The addition amount of the deterioration preventing agent is preferably 0.01 to 1% by mass of the solution (dope) to be prepared, and more preferably 0.01 to 0.2% by mass. When the addition amount is less than 0.01% by mass, the effect of the deterioration preventing agent is hardly recognized. When the addition amount exceeds 1% by mass, bleed-out (bleeding) of the deterioration preventing agent to the film surface may be observed. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

  Next, the stretching process of the polymer film will be described. The prepared cellulose acetate film (polymer film) can be further adjusted in retardation by a stretching treatment. The draw ratio is preferably 3 to 100%. The thickness of the polymer film is preferably 40 to 140 μm, and more preferably 70 to 120 μm. Further, by adjusting the conditions for the stretching treatment, the standard deviation of the slow axis angle of the optical compensation film can be reduced.

  There is no particular limitation on the stretching method, but examples thereof include a stretching method using a tenter. When the film produced by the above solvent cast method is subjected to transverse stretching using a tenter, the standard deviation of the film slow axis angle can be reduced by controlling the state of the film after stretching. Specifically, by performing a stretching process to adjust the retardation value using a tenter, and maintaining the polymer film immediately after stretching in the state in the vicinity of the glass transition temperature of the film, the standard of the slow axis angle Deviation can be reduced.

  If the film temperature during this holding is lower than the glass transition temperature, the standard deviation will increase. As another example, the standard deviation of the slow axis can be reduced by increasing the distance between the rolls when longitudinally stretching between the rolls.

  Next, the surface treatment of the polymer film will be described. When using a polymer film as a transparent protective film of a polarizing plate, it is preferable to surface-treat the polymer film. As the surface treatment, corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment or ultraviolet irradiation treatment is performed. It is particularly preferred to carry out an acid treatment or an alkali treatment, i.e. a saponification treatment on the polymer film.

  Next, the alignment film will be described. The alignment film has a function of defining the alignment direction of the discotic liquid crystalline molecules of the optically anisotropic layer. The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

  The alignment film is preferably formed by polymer rubbing treatment. Polyvinyl alcohol is a preferred polymer. Particularly preferred is a modified polyvinyl alcohol to which a hydrophobic group is bonded. Since the hydrophobic group has an affinity with the discotic liquid crystalline molecule of the optically anisotropic layer, the discotic liquid crystalline molecule can be uniformly aligned by introducing the hydrophobic group into polyvinyl alcohol.

The hydrophobic group is bonded to the main chain terminal or side chain of polyvinyl alcohol. The hydrophobic group is preferably an aliphatic group having 6 or more carbon atoms (preferably an alkyl group or an alkenyl group) or an aromatic group. When a hydrophobic group is bonded to the main chain terminal of polyvinyl alcohol, it is preferable to introduce a linking group between the hydrophobic group and the main chain terminal. Examples of the linking group include —S—, —C (CN) R ₁ —, —NR ₂ —, —CS—, and combinations thereof. The R1 and R ₂ are each (preferably, carbon atoms an alkyl group having 1 to 6) a hydrogen atom or a carbon atoms an alkyl group having 1 to 6 is.

When a hydrophobic group is introduced into the side chain of polyvinyl alcohol, a part of the acetyl group (—CO—CH ₃ ) of the vinyl acetate unit of polyvinyl alcohol is substituted with an acyl group having 7 or more carbon atoms (—CO—R). ₃ ). R ₃ is an aliphatic group or an aromatic group having 6 or more carbon atoms. Commercially available modified polyvinyl alcohol (eg, MP103, MP203, R1130, manufactured by Kuraray Co., Ltd.) may be used. The saponification degree of the (modified) polyvinyl alcohol used for the alignment film is preferably 80% or more. The degree of polymerization of (modified) polyvinyl alcohol is preferably 200 or more.

  The rubbing process is performed by rubbing the surface of the alignment film several times in a certain direction with paper or cloth. It is preferable to use a cloth in which fibers having uniform length and thickness are uniformly planted. Even if the discotic liquid crystalline molecules in the optically anisotropic layer are aligned using the alignment film, the alignment state of the discotic liquid crystalline molecules can be maintained even if the alignment film is removed. That is, the alignment film is essential in the production of the elliptically polarizing plate in order to align the discotic liquid crystalline molecules, but is not essential in the produced optical compensation film.

  When providing the alignment film between the transparent web 16 and the optically anisotropic layer, it is preferable to further provide an undercoat layer (adhesive layer) between the transparent web 16 and the alignment film. Moreover, you may add a citrate ester as needed for planar stabilization.

  Next, the optical anisotropic layer will be described. The optically anisotropic layer is formed from discotic liquid crystalline molecules. Discotic liquid crystal molecules generally have an optically negative uniaxial property. In the optical compensation film of the present invention, in the discotic liquid crystalline molecule, the angle formed by the disk surface and the transparent web 16 surface changes in the depth direction of the optically anisotropic layer (hybrid alignment). It is preferable. The optical axis of the discotic liquid crystalline molecule exists in the normal direction of the disk surface.

  The discotic liquid crystalline molecule has birefringence in which the refractive index in the disc surface direction is larger than the refractive index in the optical axis direction. The optically anisotropic layer is preferably formed by aligning the discotic liquid crystalline molecules with the alignment film and fixing the discotic liquid crystalline molecules in the aligned state. The discotic liquid crystalline molecules are preferably fixed by a polymerization reaction.

  In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is the light of wavelength λnm from the direction inclined by + 40 ° with respect to the normal direction of the film, with Re (λ) and the in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotary axis). And a retardation value measured by making light of wavelength λ nm incident from a direction inclined by −40 ° with respect to the normal direction of the film with the in-plane slow axis as the tilt axis (rotation axis). KOBRA 21ADH calculates based on the retardation value measured in a total of three directions, the assumed value of the average refractive index, and the input film thickness value.

  Here, as the assumed value of the average refractive index, the values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59).

  The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  In an optically anisotropic layer in which a discotic compound or rod-shaped compound is oriented, the tilt angle on one surface of the optically anisotropic layer (the physical target axis of the discotic compound or rod-shaped compound is the interface of the optically anisotropic layer) It is difficult to directly and accurately measure θ1 and the tilt angle θ2 of the other surface. Therefore, in this specification, θ1 and θ2 are calculated by the following method. Although this method does not accurately represent the actual orientation state of the present invention, it is effective as a means for expressing the relative relationship of some optical properties of the optical film.

  In this method, in order to facilitate calculation, the following two points are assumed and the tilt angle at the two interfaces of the optically anisotropic layer is used.

  1. The optically anisotropic layer is assumed to be a multilayer body composed of layers containing a discotic compound or a rod-like compound. Further, it is assumed that the minimum unit layer (the tilt angle of the disk-like compound or rod-like compound is assumed to be uniform in the layer) constituting it is optically uniaxial.

  2. It is assumed that the tilt angle of each layer changes monotonically with a linear function along the thickness direction of the optically anisotropic layer.

  The specific calculation method is as follows.

  (1) In a plane where the tilt angle of each layer changes monotonically with a linear function along the thickness direction of the optically anisotropic layer, the incident angle of the measurement light to the optically anisotropic layer is changed, and three or more The retardation value is measured at the measurement angle. In order to simplify the measurement and calculation, it is preferable to measure the retardation value at three measurement angles of −40 °, 0 °, and + 40 °, with the normal direction to the optically anisotropic layer being 0 °. Such measurements include KOBRA 21ADH and KOBRA WR (manufactured by Oji Scientific Instruments), transmission type ellipsometer AEP-100 (manufactured by Shimadzu Corporation), M150 and M520 (manufactured by JASCO Corporation), ABR10A (manufactured by UNIOPT Co., Ltd.) can be used.

  (2) In the above model, the refractive index of ordinary light in each layer is no, the refractive index of extraordinary light is ne (ne is the same in all layers, and no is the same), and the thickness of the entire multilayer body is Let d. Furthermore, based on the assumption that the tilt direction of each layer and the uniaxial optical axis direction of that layer coincide with each other, the calculation of the angular dependence of the retardation value of the optically anisotropic layer agrees with the measured value. Fitting is performed using the tilt angle θ1 on one surface of the anisotropic layer and the tilt angle θ2 on the other surface as variables, and θ1 and θ2 are calculated.

  Here, known values such as literature values and catalog values can be used for no and ne. If the value is unknown, it can also be measured using an Abbe refractometer. The thickness of the optically anisotropic layer can be measured by an optical interference film thickness meter, a cross-sectional photograph of a scanning electron microscope, or the like.

  Discotic liquid crystalline molecules are described in various literature (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan, Quarterly Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J. Am. Chem. Soc., Vol. 116, page 2655 (1994)). The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline molecule having a polymerizable group is preferably a compound represented by the following formula (III).

(III) D (-LQ) n
In the formula (III), D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and n is an integer of 4 to 12.

  An example of the disk-shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

  In the formula (I), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. A divalent linking group is preferred. The divalent linking group (L) is a divalent group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, —CO—, —NH—, —O—, and —S— are combined. More preferably, it is a linking group. The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -O- are combined. . The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms in the arylene group is preferably 6-10.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group).
L1: -AL-CO-O-AL-
L2: -AL-CO-O-AL-O-
L3: -AL-CO-O-AL-O-AL-
L4: -AL-CO-O-AL-O-CO-
L5: -CO-AR-O-AL-
L6: -CO-AR-O-AL-O-
L7: -CO-AR-O-AL-O-CO-
L8: -CO-NH-AL-
L9: -NH-AL-O-
L10: -NH-AL-O-CO-
L11: -O-AL-
L12: -O-AL-O-
L13: -O-AL-O-CO-
L14: -O-AL-O-CO-NH-AL-
L15: -O-AL-S-AL-
L16: -O-CO-AR-O-AL-CO-
L17: -O-CO-AR-O-AL-O-CO-
L18: -O-CO-AR-O-AL-O-AL-O-CO-
L19: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L20: -S-AL-
L21: -S-AL-O-
L22: -S-AL-O-CO-
L23: -S-AL-S-AL-
L24: -S-AR-AL-
The polymerizable group (Q) of the formula (I) is determined according to the type of polymerization reaction.

  The polymerizable group (Q) is preferably an unsaturated polymerizable group (Q1 to Q7) or an epoxy group (Q8), more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group ( Most preferably Q1-Q6). In the formula (III), n is an integer of 4 to 12. A specific number is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

  The optically anisotropic layer can be formed by applying a coating liquid containing discotic liquid crystalline molecules and, if necessary, a polymerizable initiator and optional components on the alignment film. The thickness of the optically anisotropic layer is preferably 0.5 to 100 μm, and more preferably 0.5 to 30 μm.

  The aligned discotic liquid crystal molecules are fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Description), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).

The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. Light irradiation for polymerization of discotic liquid crystalline molecules is preferably performed using ultraviolet rays. Irradiation energy is preferably 20~5000mJ / cm ^2, further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. A protective layer may be provided on the optically anisotropic layer. Moreover, you may add a citrate ester as needed for planar stabilization.

  Next, an optical film manufacturing method using the optical film manufacturing line 10 shown in FIG. 1 will be described. First, a web 16 having a thickness of 40 to 300 μm, on which a polymer layer for forming an alignment film has been previously formed, is fed out from the feeder 66. The web 16 is guided by a guide roller 68 and sent to the humidity control zone 20.

  In the humidity control zone 20, the web 16 is exposed to the set temperature and humidity atmosphere for a predetermined time, and the water content (particularly, the water content of the alignment film) is controlled within an appropriate range.

  The web 16 that has passed through the humidity control zone 20 is fed into a rubbing treatment device 70, and the polymer layer is rubbed by a rubbing roller 72. In the rubbing process, the rubbing booth 71 is exposed to the set temperature and humidity atmosphere in the rubbing booth 71, and the water content (particularly, the water content of the rubbing cloth) is controlled within an appropriate range.

  The important thing in controlling the moisture content of the web 16 (especially the moisture content of the alignment film) and the moisture content of the rubbing treatment device 70 (especially the moisture content of the rubbing cloth) is that the atmospheric humidity in the humidity control zone 20 is rubbed. More preferably, the atmospheric humidity in the humidity control zone 20 is 10% or more lower in relative humidity than the atmospheric humidity around the rubbing treatment device 70. Is to control.

  By controlling in this way, the alignment film can be maintained in a state where it is not easily damaged, and appropriate moisture is applied to the rubbing roller 72 (particularly the rubbing cloth), so that the contact area between the rubbing roller 72 (particularly the rubbing cloth) and the alignment film is increased. To increase the orientation state.

  Next, the dust attached to the surface of the web 16 is removed by the dust remover 74. Then, a gravure coating apparatus 11 applies a coating liquid containing disconematic liquid crystal to the web 16.

  Thereafter, a liquid crystal layer is formed through a drying zone 76 and a heating zone 78. Furthermore, a desired polymer is formed by irradiating the liquid crystal layer with an ultraviolet lamp 80 to crosslink the liquid crystal. The web 16 on which the polymer is formed is wound up by a winder 82.

  As mentioned above, although embodiment of the manufacturing method and apparatus of the optical film which concern on this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, in the present embodiment, a tunnel-shaped housing is adopted as the humidity control zone 20 that is a support body humidity adjusting means, but instead, it extends in the width direction of the web 16 on the upper and lower surfaces of the web 16. It is also possible to employ a configuration in which a plurality of nozzles are provided and air whose temperature and humidity are adjusted from these nozzles is blown onto the upper and lower surfaces of the web 16.

  Further, various configurations can be adopted for the rubbing booth 71 as the rubbing humidity adjusting means of the present embodiment instead.

  In the present embodiment, a coating liquid containing a disconematic liquid crystal is exemplified as the coating liquid, but other types of coating liquids for optical films, coating liquids other than for optical films, and the like can also be employed.

  The optical film (optical compensation film) was manufactured under various conditions using the optical film manufacturing line 10 shown in FIG.

  On one side of a long web 16 of triacetyl cellulose (Fujitack, manufactured by Fuji Photo Film Co., Ltd., thickness: 100 μm, width: 500 mm), a long-chain alkyl-modified poval (MP-203, Kuraray Co., Ltd.) (Product made) A 5% by weight solution was applied, dried at 90 ° C. for 4 minutes, and then rubbed to form an alignment film-forming resin layer having a thickness of 2.0 μm.

  The conveyance speed of the web 16 was 20 m / min. The alignment layer-forming resin layer was formed using an optical film production line 10 shown in FIG.

  The web 16 is sent out from the delivery device 66 of the optical film production line 10 on which the web 16 is wound, at a conveyance speed of 20 m / min, and is sent into the humidity control zone 20.

  In this humidity control zone 20, the sample of each condition was created by changing temperature, relative humidity, and processing time. The temperature is two conditions of 25 ° C and 30 ° C, the relative humidity is three conditions of 7%, 46% and 79%, and the treatment time is 1 second, 3 seconds, 5 seconds and 10 seconds. These four conditions were used.

  Next, the surface of the resin layer was rubbed with the rubbing apparatus 70 while the web 16 was continuously conveyed at 20 m / min. In the rubbing treatment, the rubbing roller 72 was rotated at 300 rpm, and then the resulting alignment film was dedusted. At this time, the relative humidity of the rubbing booth 71 was controlled to be 46%. The moisture content of the rubbing cloth at this time was measured and found to be 8.3%.

  In addition to this, a sample in which the relative humidity of the rubbing booth 71 was controlled so as to be 7% and 79% was also prepared in order to evaluate the orientation due to the Schlieren failure described later.

Next, while the web 16 having the obtained alignment film is continuously conveyed at 20 m / min, the weight ratio of (3) of the discotic compound TE-8 to (5) of the TE-8 is formed on the alignment film. A 10% by weight methyl ethyl ketone solution (coating solution) of a mixture obtained by adding 1% by weight of a photopolymerization initiator (Irgacure 907, Nippon Ciba Geigy Co., Ltd.) to the above mixture to a 4: 1 mixture by gravure coating device 11 was applied at a coating amount of 5 ml / m ² and then passed through a drying zone 76 and a heating zone 78.

  A wind of 0.1 m / sec was sent to the drying zone 76, and the heating zone 78 was adjusted to 130 ° C. The web 16 entered the drying zone 76 3 seconds after application and entered the heating zone 78 after another 3 seconds. Web 16 passed through heating zone 78 in about 3 minutes.

  Next, while the web 16 coated with the alignment film and the liquid crystal layer was continuously conveyed at 20 m / min, the surface of the liquid crystal layer was irradiated with ultraviolet rays by an ultraviolet lamp 80. That is, the web 16 passed through the heating zone 78 was irradiated with ultraviolet rays having an illuminance of 600 mW for 4 seconds by an ultraviolet lamp 80 (output: 160 W / cm, emission length: 1.6 m) to crosslink the liquid crystal layer.

  Further, the web 16 on which the alignment film and the liquid crystal layer are formed has its surface optical characteristics measured by an inspection device and inspected, and then a protective film is laminated on the surface of the liquid crystal layer by a laminating machine (not shown) and wound. The film was wound up by a machine 82 to obtain an optical compensation film.

  The obtained optical compensation film was evaluated. There are two types of evaluation: 1) evaluation of orientation by extinction value, and 2) evaluation of orientation by schlieren failure.

1) Evaluation of orientation based on extinction value For evaluation of orientation based on the extinction value, an extinction degree measuring device manufactured by Otsuka Electronics Co., Ltd. was used. In this apparatus, the measurement wavelength was 550 nm, and the transmittance of the polarizing plate in the paranicol arrangement was 100%. Then, the orientation of two discotic liquid crystals arranged in crossed Nicols was evaluated.

  In the evaluation of the orientation based on the extinction value, the lower the extinction value, the higher the orientation. Evaluation of orientation is based on the following four-step evaluation. A: Good orientation, B: Normal level, B: Somewhat poor orientation, X: Poor orientation.

  The evaluation results are shown in the table of FIG. In this table, (A) shows the temperature of the humidity control zone 20 controlled to 25 ° C, and (B) shows the temperature of the humidity control zone 20 controlled to 30 ° C.

  From the above results, when the treatment time was 1 second and 3 seconds, the orientation was the normal level (◯) regardless of the relative humidity of the humidity control zone 20, and no difference in orientation occurred.

  On the other hand, when the processing time was 5 seconds and 10 seconds, the orientation was poor when the relative humidity of the humidity control zone 20 was high (79%).

2) Evaluation of orientation due to schlieren failure For evaluation of orientation due to schlieren failure, photography using a polarizing microscope (manufactured by Nikon, model number: ECLIPSE E600 POL) was employed. This Schlieren failure is a failure that occurs when the orientation of the liquid crystal phase deteriorates.

  The evaluation results are shown in the table of FIG. In this table, the vertical column is the relative humidity of the humidity control zone 20, and the horizontal column is the relative humidity of the rubbing booth 71. The temperature of the humidity control zone 20 was controlled at 25 ° C. In each table, the number of schlieren failures that occurred is listed.

  From the results in the table, it was found that the relative humidity of the rubbing booth 71 was 71%, and the orientation of the relative humidity of the humidity control zone 20 was 46% and 7% was good.

  That is, it is confirmed that a good orientation state can be obtained by controlling the humidity of the humidity control zone 20 (support humidity adjusting means) to be equal to or less than the atmospheric humidity of the rubbing booth 71 (around the rubbing device 70). It was done.

Explanatory drawing which shows the production line of the optical film with which the manufacturing method and apparatus of the optical film concerning this invention are applied Table showing results of examples Table showing results of examples

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical film production line, 11 ... Gravure coating apparatus, 12 ... Gravure roller, 14 ... Liquid receiving pan, 16 ... Web, 20 ... Humidity control zone, 66 ... Delivery machine, 68 ... Guide roller, 70 ... Rubbing processing apparatus 71 ... rubbing booth, 72 ... rubbing roller, 74 ... dust remover, 76 ... drying zone, 78 ... heating zone, 80 ... ultraviolet lamp, 82 ... winder, 84 ... roller stage, 86, 88 ... backup roller

Claims (6)

While continuously running the belt-like flexible support, the surface of the support is subjected to a rubbing process by a rubbing apparatus, and the surface of the support after the rubbing process is coated with a coating solution by a coating means, thereby functional film. In the method for producing an optical film for forming
A support humidity adjusting means is provided on the upstream side of the rubbing device to control the water content of the support,
A method for producing an optical film, wherein the rubbing apparatus is covered with a rubbing humidity adjusting means to control the atmospheric humidity around the rubbing apparatus.   The manufacturing method of the optical film of Claim 1 which controls so that the atmospheric humidity of the said support body humidity adjustment means becomes below the atmospheric humidity around the said rubbing apparatus.   The method for producing an optical film according to claim 1, wherein the atmospheric humidity of the support humidity adjusting means is controlled to be 10% or more lower in relative humidity than the atmospheric humidity around the rubbing apparatus.   The method for producing an optical film according to claim 1, wherein the support is a polymer film.   The method for producing an optical film according to claim 1, wherein the optical film is an optical compensation film. Support running means for continuously running the belt-like flexible support; and
A rubbing apparatus for rubbing the surface of the support;
A support humidity adjusting means provided on the upstream side of the rubbing device for controlling the water content of the support;
Rubbing humidity adjusting means for covering the rubbing apparatus and controlling the atmospheric humidity around the rubbing apparatus;
A coating means for coating a coating solution on the surface of the support after the rubbing treatment;
An optical film manufacturing apparatus comprising:

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