JP2008050581A - Cellulose acylate film, and polarizing plate and liquid crystal display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film having small optical anisotropy (Re, Rth), to provide an excellent polarizing plate which uses the cellulose acylate film, and little causes the deterioration of polarizers after the passage of long periods at high humidities, and to provide a liquid crystal display which uses the cellulose acylate film and has a high display grade in a wide angle of visibility. <P>SOLUTION: A cellulose acylate film comprising at least a compound selected from polymers of ethylenic unsaturated monomer or polycondensates produced from organic acids and glycols is characterized in that the content of the ethylenic unsaturated monomer or a low molecular weight ester compound comprising the raw materials for the polycondensates, contained in the film, is ≤1 mass% per the cellulose acylate film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cellulose acylate film, and a polarizing plate and a liquid crystal display device using the same.

  Conventionally, cellulose acylate films have been used for photographic supports and various optical materials because of their toughness and flame retardancy. In particular, in recent years, it has been widely used as an optical transparent film for liquid crystal display devices. Cellulose acylate films are excellent as optical materials for devices that handle polarized light such as liquid crystal display devices because of their high optical transparency and high optical isotropy. It has been used as a support for optical protective films that can improve (viewing angle compensation) a protective film and a display viewed from an oblique direction.

  In recent liquid crystal display devices, improvement in viewing angle characteristics is strongly demanded, and optical transparent films such as a protective film for a polarizer and a support for an optical compensation film are more optically isotropic. It is required to be sex. In order to be optically isotropic, it is important that the retardation value represented by the product of birefringence and thickness of the optical film is small. In particular, in order to improve display from an oblique direction, it is necessary to reduce not only the retardation (Re) in the front direction but also the retardation (Rth) in the film thickness direction. Specifically, when evaluating the optical properties of the optical transparent film, it is required that Re measured from the front of the film is small and that Re does not change even when measured at different angles.

  So far, cellulose acylate films having a small front Re have been known. However, it was difficult to produce a cellulose acylate film having a small Re change depending on the angle, that is, a small Rth. There is a strong demand for an optically isotropic optically transparent film in which Re on the front surface of the cellulose acylate film is almost zero and the change in retardation angle is small, that is, Rth is also almost zero.

  In the production of a cellulose acylate film, a compound called a plasticizer is generally added to improve the film forming performance. Types of plasticizers include phosphate triesters such as triphenyl phosphate and biphenyl diphenyl phosphate; phthalates. Among these plasticizers, those having the effect of reducing the optical anisotropy of the cellulose acylate film are known (for example, specific fatty acid esters, see Patent Document 1). The effect of reducing the mechanical anisotropy is not sufficient.

In addition, by containing a polymer obtained by polymerizing an ethylenically unsaturated monomer mainly composed of a monomer selected from vinyl ester and acrylic acid ester in a cellulose ester film, it is possible to remove defects and foreign matters from the polarizing plate protective film, and It has been disclosed that whitening of edges in a high temperature and humidity state can be reduced (see Patent Document 2). Furthermore, it is disclosed that the protective film for polarizing plates which consists of a cellulose-ester film containing polyester is excellent in dimensional stability (for example, patent document 3). However, recent liquid crystal display devices are increasingly used outdoors such as mobile and in-vehicle applications, and the stability of the performance of the polarizing plate in a high-temperature and high-humidity state has become important.
JP 2001-247717 A JP 2002-20410 A Japanese Patent Laid-Open No. 2002-22756

  An object of the present invention is to provide a cellulose acylate film having small optical anisotropy (Re, Rth), and an excellent polarizing plate using the same and having little deterioration of a polarizer over a long period of time at high humidity. That is.

  As a result of intensive studies, the present inventors have achieved the object of the present invention with the cellulose acylate film described below.

(1)
A cellulose acylate film containing a polymer of an ethylenically unsaturated monomer, wherein the ethylenically unsaturated monomer contained in the film is 1% by mass or less per cellulose acylate film. Rate film.
(2)
The cellulose acylate film according to (1), wherein the polymer is an acrylic polymer.
(3)
At least one polycondensate selected from the group consisting of polycondensates obtained by polycondensation of organic acids, glycols and monohydric alcohols, and polycondensates obtained by polycondensation of organic acids and glycols A low molecular weight ester compound obtained by condensing 5 or less molecules, which is a raw material of the polycondensate, contained in the film, is contained in the film in an amount of 1 per cellulose acylate film. A cellulose acylate film characterized by being less than or equal to mass%.
(4)
The cellulose acylate film according to any one of (1) to (3), wherein the cellulose acylate film further contains an ultraviolet absorber, and the ultraviolet absorber is liquid at 25 ° C.
(5)
The acyl substitution degree of the cellulose acylate in the cellulose acylate film is 2.50 to
The cellulose acylate film according to any one of (1) to (4), which is 3.00 and has an average polymerization degree of 180 to 700.
(6)
The acyl substituent of the cellulose acylate in the cellulose acylate film consists essentially of an acetyl group, the total degree of substitution is 2.50 to 2.95, and the average degree of polymerization is 180 to 550 ( The cellulose acylate film according to any one of 1) to (5).
(7)
The cellulose acylate film according to any one of (1) to (6), wherein the thickness of the cellulose acylate film is 10 to 120 μm.
(8)
The cellulose acylate film according to any one of (1) to (7), wherein Rth and Re at a wavelength of 630 nm of the cellulose acylate film satisfy the following formulas (1) and (2), respectively.
Formula (1): −25 nm ≦ Rth (630) ≦ 25 nm,
Formula (2): 0 nm ≦ Re (630) ≦ 10 nm
(9)
A polarizing plate in which a protective film is bonded to both sides of a polarizer, wherein at least one of the protective films is the cellulose acylate film according to any one of (1) to (8). Board.
(10)
A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein at least one polarizing plate is the polarizing plate described in (9).
(11)
The liquid crystal display device according to (10), wherein the liquid crystal display device is in an IPS mode.

  Through the research of the present inventors, a cellulose acylate film having a small optical anisotropy Re and Rth can be produced. Using this cellulose acylate film, an optical material such as an optical compensation film and a polarizing plate, and these It has become possible to provide a liquid crystal display device using this. Furthermore, it is possible to provide an excellent polarizing plate in which the deterioration of the polarizer is small over a long period of time at high humidity.

<Cellulose acylate film>
The cellulose acylate film of the present invention is a cellulose acylate film containing a polymer of an ethylenically unsaturated monomer, or a polycondensate obtained by polycondensation of an organic acid and glycol. Low molecular ester compound comprising an ethylenically unsaturated monomer contained in or a raw material of the polycondensate (the low molecular ester compound is composed of 5 or less molecules selected from organic acids, glycols and monohydric alcohols as raw materials) Is 1% by mass or less per cellulose acylate film.
Hereinafter, a polymer of an ethylenically unsaturated monomer used in the present invention and a polycondensate composed of an organic acid and glycol will be described.

[Polymer of ethylenically unsaturated monomer]
The polymer preferably has a mass average molecular weight of 500 or more and 10,000 or less, and is considered to be between an oligomer and a low molecular weight polymer. When the mass average molecular weight is 10,000 or less, the compatibility with the cellulose ester is good, and the occurrence of bleed out can be suppressed. The mass average molecular weight is more preferably 800 or more and 8,000 or less, and further preferably 1000 or more and 5,000 or less. The molecular weight distribution of the polymer of the present invention can be measured and evaluated by gel permeation chromatography.

[Ethylenically unsaturated monomer]
Although the ethylenically unsaturated monomer which guide | induces the polymer unit which comprises the polymer used by this invention is mentioned below, it is not limited to these.

  Examples of the above ethylenically unsaturated monomers that can be used in the present invention include: vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, vinyl caproate, vinyl caprate, laurin Vinyl acetate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonic acid, vinyl sorbate, vinyl benzoate, vinyl cinnamate, etc .; acrylic ester and methacrylic acid Examples of the acid ester {hereinafter sometimes referred to as (meth) acrylic acid ester} include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate (i-, n-), ( Meth) butyl acrylate (n-, i-, -, T-), pentyl (meth) acrylate (n-, i-, s-), hexyl (meth) acrylate (n-, i-), heptyl (meth) acrylate (n-, i-) Octyl (meth) acrylate (n-, i-), nonyl (meth) acrylate (n-, i-), myristyl (meth) acrylate (n-, i-), cyclohexyl (meth) acrylate, (Meth) acrylic acid (2-ethylhexyl), (meth) acrylic acid (ε-caprolactone), (meth) acrylic acid (4-methylcyclohexyl), (meth) acrylic acid (4-ethylcyclohexyl), (meth) acrylic Acid (2-methoxyethyl), (meth) acrylic acid (2-ethoxyethyl), (meth) acrylic acid (2-hydroxyethyl), (meth) acrylic acid (2-hydroxypropyl), (meth) Acrylic acid (3-hydroxypropyl), (meth) acrylic acid (4-hydroxybutyl), (meth) acrylic acid (2-hydroxybutyl), etc .; examples of aromatic monomers include styrene, α-methylstyrene, Vinyltoluene, 4-[(2-butoxyethoxy) methyl] styrene, 4-butoxymethoxystyrene, 4-butylstyrene, 4-decylstyrene, 4- (2-ethoxymethyl) styrene, 4- (1-ethylhexyloxymethyl) ) Styrene, 4-hydroxymethyl styrene, 4-octyloxymethyl styrene, 4-octyl styrene, 4-propoxymethyl styrene, phenyl (meth) acrylate, (meth) acrylic acid (2 or 4-chlorophenyl), (meth) Acrylic acid (2,3 or 4-ethoxycarbonylphenyl , (Meth) acrylic acid (o, m or p-tolyl), benzyl (meth) acrylate, phenethyl (meth) acrylate, (meth) acrylic acid (2-naphthyl), (meth) acrylic acid-p-hydroxy Examples of unsaturated acids include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, and itaconic acid.

  The polymer composed of the above monomers may be a copolymer or a homopolymer, such as a homopolymer of vinyl ester, a copolymer of vinyl ester, a copolymer of vinyl ester and (meth) acrylate, a homopolymer of (meth) acrylate or Copolymers are preferred. Among these polymers, a copolymer of vinyl ester and (meth) acrylic acid ester, and an acrylic polymer that is a homopolymer or copolymer of (meth) acrylic acid ester are more preferable.

In the present invention, as a polymer unit based on the (meth) acrylic acid ester in the polymer, a polymer unit based on the (meth) acrylic acid ester having an aromatic ring or a cyclohexyl group in the side chain is set to a sub-quantity. An acrylic polymer may be used.
When the acrylic polymer contains a polymer unit based on (meth) acrylic acid ester containing an aromatic ring or cyclohexyl group in the side chain, (meth) acrylic acid containing an aromatic ring or cyclohexyl group in the side chain in the polymer It is preferable that the polymer unit based on ester has 20 to 40% by mass and the polymer unit based on (meth) acrylic acid ester having no aromatic ring and cyclohexyl group has 50 to 80% by mass. Moreover, 2-20 mass% of polymer units based on the (meth) acrylic acid ester which has the below-mentioned hydroxyl group in this polymer can also be included.

  Among the (meth) acrylic acid ester monomers, examples of (meth) acrylic acid ester monomers having no aromatic ring and cyclohexyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic. Propyl (i-, n-), butyl (meth) acrylate (n-, i-, s-, t-), pentyl (meth) acrylate (n-, i-, s-), (meth) Hexyl acrylate (n-, i-), heptyl (meth) acrylate (n-, i-), octyl (meth) acrylate (n-, i-), nonyl (meth) acrylate (n-, i -), Myristyl (meth) acrylate (n-, i-), (meth) acrylic acid (2-ethylhexyl), (meth) acrylic acid (ε-caprolactone), (meth) acrylic acid (2-hydroxyethyl) , ( T) Acrylic acid (2-hydroxypropyl), (meth) acrylic acid (3-hydroxypropyl), (meth) acrylic acid (4-hydroxybutyl), (meth) acrylic acid (2-hydroxybutyl), (meth) Examples include acrylic acid (2-methoxyethyl) and (meth) acrylic acid (2-ethoxyethyl).

The acrylic polymer that is particularly preferably used in the present invention is a homopolymer or copolymer of the above-mentioned monomers. Among them, it is more preferable that the acrylic acid methyl ester monomer unit has 30% by mass or more, and methacrylic acid. More preferably, the methyl ester monomer unit has 40% by mass or more. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

  In the acrylic polymer, a polymer unit based on a (meth) acrylic acid ester monomer having a hydroxyl group can be preferably used. The monomer having a hydroxyl group is the same as the monomer described above, but (meth) acrylic acid ester is preferable, for example, (meth) acrylic acid (2-hydroxyethyl), (meth) acrylic acid (2-hydroxypropyl) , (Meth) acrylic acid (3-hydroxypropyl), (meth) acrylic acid (4-hydroxybutyl), (meth) acrylic acid (2-hydroxybutyl), (meth) acrylic acid-p-hydroxymethylphenyl, ( Examples include meth) acrylic acid-p- (2-hydroxyethyl) phenyl, and preferred are 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. The polymer unit based on the (meth) acrylic acid ester monomer having a hydroxyl group in the polymer is preferably contained in the polymer in an amount of 2 to 20% by mass, more preferably 2 to 10% by mass.

  As the ethylenically unsaturated monomer having a functional group useful for the polymer of the present invention, those having an ultraviolet absorbing group or an antistatic group in the side chain of the polymer may be used. Any copolymer can be used as long as it has a Tg of 50 ° C. or lower. The ethylenic group of the ethylenically unsaturated monomer having a functional group is preferably a vinyl group, an acryloyl group or a methacryloyl group, and these are preferably used.

  Examples of the ultraviolet absorbing group of the ethylenically unsaturated monomer having an ultraviolet absorbing group useful in the present invention include a benzotriazole group, a salicylic ester group, a benzophenone group, an oxybenzophenone group, and a cyanoacrylate group. Any of them can be preferably used in the invention.

  Examples of the ethylenically unsaturated monomer having a UV-absorbing group include UV-absorbing monomers constituting UV-absorbing polymers described in JP-A-6-148430, and UV-absorbing monomers described in JP-A-2002-20410. Can be preferably used.

  Examples of the antistatic group of the ethylenically unsaturated monomer having an antistatic group include a quaternary ammonium group, a sulfonate group, and a polyethylene oxide group. From the viewpoint of solubility and charging performance, 4 A quaternary ammonium group is preferred. An ethylenically unsaturated monomer having an antistatic group described in JP-A-2002-20410 can be preferably used.

  Recently, the stability of the performance of polarizing plates in a hot and humid state has become increasingly important. The inventors of the present invention have intensively studied to further improve the stability of the performance of the polarizing plate in a hot and humid state. As a result, when a cellulose acylate film containing a polymer of an ethylenically unsaturated monomer is used as the polarizing plate protective film, the ethylenically unsaturated monomer contained in the film, that is, the polymer accompanying the polymer It has been found that it is effective to reduce the content of residual unreacted monomer contained in the film.

  It is known that iodine molecules contained in a polarizer of a polarizing plate interact with an electron donor compound such as triethylamine (for example, J. Am. Chem. Soc. 80, 520, 1958). . Since the ethylenically unsaturated monomer is also an electron donor compound, if such a compound is contained in the polarizing plate protective film, it interacts with iodine molecules in the adjacent polarizer, which causes the polarizer. It is thought that the deterioration of this occurs.

  The ethylenically unsaturated monomer contained in the cellulose acylate film of the present invention needs to be 0 to 1% by mass, preferably 0 to 0.7% by mass, and more preferably 0 to 0.6% by mass. 0 to 0.2% by mass is most preferable.

  The adjustment of the amount of residual monomer in the polymer can be reduced by a known method such as selecting the type of solvent for precipitation after the completion of polymerization or increasing the number of precipitations. After the polymerization is completed, the monomer can be volatilized by heating the polymer.

  The amount of residual monomer in the film can be easily quantified with a gas chromatograph or the like.

[Specific Examples of Polymer Used in the Present Invention]
Although the specific example of the polymer used by this invention below is shown, it is not limited to these.

  The addition amount of the polymer in the present invention is preferably 0.01 to 30% by mass, more preferably 1 to 25% by mass, and 5 to 20% by mass with respect to cellulose acylate. Particularly preferred.

  The polymer in this invention may be used independently, or 2 or more types of compounds may be mixed and used by arbitrary ratios.

  In the present invention, the polymer may be added at any time during the dope production process, or may be performed at the end of the dope preparation process.

  The method for synthesizing the polymer in the present invention is as follows: a method using a peroxide polymerization initiator such as cumene peroxide or t-butyl hydroperoxide; a method using a polymerization initiator in a larger amount than a normal polymerization; In addition, a method using a chain transfer agent such as a mercapto compound or carbon tetrachloride; a method using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator; and further, JP 2000-128911 A or 2000 A method of bulk polymerization using a compound having one thiol group and a secondary hydroxyl group, or a polymerization catalyst in which the compound and an organometallic compound are used in combination, as described in JP-A-344823; And synthesis methods described in JP-A No. 2003-12859, etc., all of which are preferably used in the present invention. It is.

  The ethylenically unsaturated monomer content of these polymers can be adjusted by crystallization of the polymer, distillation under reduced pressure, or by repeating these.

[Condensation polymer of organic acid and glycol]
The condensation polymer of the organic acid and glycol of the present invention has a mass average molecular weight of 500 or more and 10,000.
The following are preferred and are considered to be between the oligomer and the low molecular weight polymer. When the mass average molecular weight is 10,000 or less, the compatibility with the cellulose ester is good, and the occurrence of bleed out can be suppressed. The mass average molecular weight is more preferably from 800 to 5,000, and even more preferably from 1,000 to 3,000. The molecular weight distribution of the polymer of the present invention can be measured and evaluated by gel permeation chromatography.

The organic powder forming the basic skeleton of the condensation polymer of the present invention is preferably a dibasic acid.
As the dibasic acid, an aliphatic dibasic acid, an alicyclic dibasic acid, and an aromatic dibasic acid are preferable. For example, as the aliphatic dibasic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelin Acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, etc., aromatic dibasic acids include phthalic acid, terephthalic acid, isophthalic acid, 1,4-xylidenedicarboxylic acid, alicyclic Examples of the dibasic acid include 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-cyclohexanediacetic acid and the like. In particular, aliphatic dicarboxylic acids having 4 to 12 carbon atoms, alicyclic dibasic acids and aromatic dicarboxylic acids are preferred, and two or more dibasic acids selected from these may be used in combination.

  As glycols, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4 -Butylene glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,5-pentylene glycol, 1,4-cyclohexanedimethanol , Neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, etc., among which ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol and triethylene glycol are preferred, and 1,3-propylene glycol, 1, 4-butylene glycol 1,6-hexanediol and diethylene glycol are more preferred. Glycols may be used alone or in combination of two or more. The terminal of the condensation polymer can also be blocked with a monovalent alcohol having 2 to 20 carbon atoms or a monovalent carboxylic acid having 2 to 20 carbon atoms.

The polycondensate of the present invention is preferably a compound represented by the following general formula (I) or (II).
General formula (I) R- (AG) _m -AR
General formula (II) S- (GA) _m- GS
In general formulas (I) and (II), A is a dibasic acid residue having an average of 2 to 10 carbon atoms, G is a glycol residue having an average of 2 to 6 carbon atoms, and R is carbon. A monovalent alcohol residue having an average number of 2 to 20 and S is a monovalent carboxylic acid residue having an average number of carbon atoms of 2 to 20. m is an integer of 1 or more.

  As the dibasic acid, succinic acid, adipic acid, sebacic acid, phthalic acid, terephthalic acid, and 1,4-cyclohexyldicarboxylic acid are preferable, and succinic acid, adipic acid, and phthalic acid are more preferable.

Although the specific example of the condensation polymer of a dibasic acid and glycol is given to the following, it is not limited to these.
Polyester polyols described in JP-A-2006-64803, for example, polyester polyol PEO-1 (polyester polyol composed of succinic acid and 1,4-butylene glycol, average carbon number of glycol is 3.3, carbon of dibasic acid Number 4), PEO-2
(Polyester polyol composed of adipic acid, 1,4-butylene glycol and ethylene glycol, the average number of carbon atoms of glycol is 3.3, the number of carbon atoms of dibasic acid is 6), polyester described in JP-A-2006-342227 , For example, PE-1 (polyester composed of succinic acid and ethylene glycol, end-capped with 2-ethylhexyl group (terminated)), PE-2 (polyester composed of adipic acid, 1,4-butylene glycol and ethylene glycol, The average number of carbon atoms of glycol is 3.33, the number of carbon atoms of dibasic acid is 6, and PE-3 (polyester composed of adipic acid and succinic acid and ethylene glycol, the average number of carbon atoms of glycol is 2, The carbon number is 4.5), Polycizer W-2640S, Polycizer W-305ELS, Poly Sizer P-103, Polylite OD-X-286, Polylite OD-X-2251, Polylite OD-X-2802 (Dainippon Ink Co., Ltd.), Adeka Sizer PN150, Adeka Sizer PN170, Adeka Sizer PN7120, Adeka Sizer PN1010, Adeka Sizer PN1430, Adeka Sizer PN77 (Asahi Denka Kogyo Co., Ltd.), D643, D633, D620, D671 (J Plus Corporation), Cosmall 102 (Nisshin Oilio Co., Ltd.).

  The low molecular ester compound made of the raw material of the condensation polymer of the present invention is composed of the raw material dibasic acid, glycol, monohydric alcohol or monovalent carboxylic acid. Here, the low molecular ester is composed of 5 or less molecules selected from organic acids, glycols, and monohydric alcohols as raw materials.

The component composed of 6 or more molecules has little influence on the performance over time of the polarizing plate made of the cellulose acylate film containing the condensation polymer, and contains a low molecular ester compound composed of 5 or less molecules A small amount is preferred. More preferably, the content of the low molecular ester compound composed of 3 or less molecules is preferably small.
Specifically, for example, bis (2-ethylhexyl) adipate, dinonyl adipate, bis (4-hydroxybutyl) adipate, bis (2-hydroxybutyl) succinate, bis (2-ethylhexyl) succinate, phthalic acid And bis (5-hydroxy-3-methylpentyl). The content of these low molecular esters can be adjusted by crystallization of the condensation polymer, distillation under reduced pressure, or by repeating these.

  The measurement of the amount of low molecular ester in the film can be easily quantified with a gas chromatograph or the like.

  The polycondensate of the present invention is synthesized by a conventional method. For example, a direct reaction between the dibasic acid and glycol, the dibasic acid or an alkyl ester thereof, for example, a polyesterification reaction or transesterification reaction between a dibasic acid methyl ester and a glycol, or a hot melt condensation method, Alternatively, it can be easily synthesized by any method of dehydrohalogenation reaction between acid chloride of these acids and glycol, but polyester having a mass average molecular weight not so large is preferably by direct reaction. A conventional method can be used as the molecular weight adjusting method without any particular limitation. For example, depending on the polymerization conditions, the amount added can be controlled by a method of blocking the molecular ends with a monovalent acid or monovalent alcohol.

  The addition amount of the polycondensate of the present invention is preferably 0.01 to 30% by mass, more preferably 1 to 25% by mass, and 5 to 20% by mass with respect to cellulose acylate. Is particularly preferred.

  The polycondensate of the present invention may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.

The polycondensate of the present invention may be added at any time during the dope production process, or may be performed at the end of the dope preparation process.

  The cellulose acylate film of the present invention preferably contains a polymer of an ethylenically unsaturated monomer in that the retardation can be reduced.

In the polycondensate composed of a polymer of an ethylenically unsaturated monomer or an organic acid and glycol in the present invention, Rth (630) preferably satisfies the following mathematical formula (3).
Formula (3): | Rth (a) −Rth (0) | /a≧1.0
Rth (a): Rth (nm) at a wavelength of 630 nm of a cellulose acylate film containing a% of a retardation regulator
Rth (0): Rth (nm) at a wavelength of 630 nm of a cellulose acylate film containing no retardation regulator
a: part by mass of the retardation regulator with respect to 100 parts by mass of cellulose acylate, and the value is in the range of 0.01 ≦ a ≦ 30.

Furthermore, the polymer in the present invention more preferably satisfies the following formula (3-1), and more preferably satisfies the following formula (3-2).
Formula (3-1): (Rth (a) −Rth (0)) / a ≦ −1.5
Formula (3-2): (Rth (a) −Rth (0)) / a ≦ −2.0
Note that Rth (a), Rth (0), and the ranges of a and a are as defined in the above equation (3).

[Ultraviolet absorber]
The cellulose acylate film of the present invention preferably contains an ultraviolet absorber.

  As the ultraviolet absorber, any type can be selected according to the purpose, and a salicylic acid ester, benzophenone, benzotriazole, triazine, benzoate, cyanoacrylate, nickel complex, etc. It is possible to use benzophenone, benzotriazole, and triazine.

  The UV absorber in the present invention preferably has a molecular weight of 250 to 1000 from the viewpoint of volatility. More preferably, it is 260-800, More preferably, it is 270-800, Most preferably, it is 300-800. Within the range of these molecular weights, a specific monomer structure may be used, or a multimer, oligomer structure, or polymer structure in which a plurality of the monomer units are bonded may be used.

  Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone.

  As the benzotriazole ultraviolet absorber, 2 (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2 (2′-hydroxy-5′-t-butylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5 Examples include chlorobenzotriazole, 2 (2′-hydroxy-5′-t-octylphenyl) benzotriazole, and the like.

  Examples of the triazine-based ultraviolet absorber include compounds disclosed in JP-A-10-182621, or the following compounds (UVT-1 to 4).

  The ultraviolet absorber used in the present invention is preferably liquid at 25 ° C. The liquid ultraviolet absorber is a liquid ultraviolet absorber which is liquid at a so-called normal temperature and 1 atm. Here, “liquid at normal temperature” means a liquid that does not have a certain shape, is fluid, and has a substantially constant volume, as defined in “Chemical Encyclopedia (1963) Kyoritsu Publishing” at 25 ° C. Show. Therefore, the melting point is not limited as long as it has the above properties, but a compound having a melting point of 30 ° C. or lower, particularly preferably 15 ° C. or lower is preferable.

  For example, when a liquid UV agent (UVT-23L, UVT-28L) is used, the polarizing plate durability can be transmitted even when there is a residual monomer derived from the polymer, compared to the powder “Tinuvin 326 (TN326)”. The rate change can be reduced.

  The liquid ultraviolet absorber may be a single compound or a mixture, and as the mixture, those composed of a structural isomer group can be preferably used.

The liquid ultraviolet absorber can have any structure as long as the above conditions are satisfied, but 2- (2′-) represented by the following general formula (1) from the viewpoint of light fastness of the ultraviolet absorber itself. Hydroxyphenyl) benzotriazole compounds are particularly preferred.
General formula (1):

In the general formula (1), R ₁ , R ₂ and R ₃ each represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkenyl group, a nitro group or a hydroxyl group.

  Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom, and a chlorine atom is particularly preferable.

  As the alkyl group and alkoxy group, those having 1 to 30 carbon atoms are preferable, and as the alkenyl group, those having 2 to 30 carbon atoms are preferable. These groups may be linear or branched. These alkyl group, alkoxy group and alkenyl group may further have a substituent. Specific examples of the alkyl group, alkoxy group and alkenyl group include, for example, methyl group, ethyl group, isopropyl group, t-butyl group, s-butyl group, n-butyl group, n-amyl group, s-amyl group, t -Amyl group, octyl group, nonyl group, dodecyl group, eicosyl group, α, α-dimethylbenzyl group, octyloxycarbonylethyl group, methoxy group, ethoxy group, octyloxy group, allyl group and the like.

  As the aryloxy group and aryl group, for example, a phenyl group and a phenyloxy group are particularly preferable and may have a substituent. Specific examples include a phenyl group, 4-t-butylphenyl group, 2,4-di-t-amylphenyl group, and the like.

Of the groups represented by R ₁ and R ₂ , a hydrogen atom, an alkyl group, an alkoxy group, and an aryl group are preferable, and a hydrogen atom, an alkyl group, and an alkoxy group are particularly preferable.

Of the groups represented by R ₃ , a hydrogen atom, a halogen atom, an alkyl group, and an alkoxy group are particularly preferable, and a hydrogen atom, an alkyl group, and an alkoxy group are more preferable.

Of the groups represented by R ₁ , R ₂ and R ₃ , at least one is preferably an alkyl group and more preferably at least two are alkyl groups in order to become liquid at room temperature.

The alkyl group may take any form, but at least one is preferably a tertiary alkyl group or a secondary alkyl group. In particular, at least one of the alkyl groups represented by R ₁ and R ₂ is preferably a tertiary alkyl group or a secondary alkyl group.

  Below, the typical example of the liquid ultraviolet absorber preferably used for this invention is shown.

  As the ultraviolet absorber, it is preferable to use a combination of a plurality of absorbers having different absorption wavelengths because a high blocking effect can be obtained in a wide wavelength range. The ultraviolet absorbent for liquid crystal is preferably one that is excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal and that has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties.

  As for the UV absorber, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-107854. 118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, JP-A-2000-204173 These compounds can also be used.

  0.001-5 mass% is preferable with respect to a cellulose acylate, and, as for the addition amount of a ultraviolet absorber, 0.01-1 mass% is more preferable. If the addition amount is 0.001% by mass or more, the effect of addition can be sufficiently exerted, and if the addition amount is 5% by mass or less, it is preferable because bleeding out of the ultraviolet absorber to the film surface can be suppressed.

  Further, the ultraviolet absorber may be added simultaneously with dissolution of cellulose acylate, or may be added to the dope after dissolution. It is preferable to add to the dope after dissolution. When adding to the dope after dissolution, the form of adding an ultraviolet absorber solution to the dope immediately before casting using a static mixer or the like easily adjusts the spectral absorption characteristics. This is particularly preferable.

[Retardation of cellulose acylate film]
The retardation Re and Rth will be described in detail below.
In the present invention, Re (λ) and Rth (λ) represent the retardation in the front direction and the retardation in the thickness direction at the wavelength λ, respectively.

[Measurement of retardation value]
A method for measuring the retardation of the cellulose acylate film of the present invention will be described.

(Retardation Re in the front direction, retardation Rth in the film thickness direction)
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 using “KOBRA 21ADH” or “KOBRA WR” {manufactured by Oji Scientific Instruments Co., Ltd.) with light having a wavelength of λ nm incident in the normal direction of the film.

When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is an in-plane slow axis (determined by “KOBRA 21ADH” or “KOBRA WR”) as an inclined axis (rotation axis) (in the absence of a slow axis, any arbitrary in-plane film) Retardation of 6 points in total by making light of wavelength λ nm incident from the inclined direction in 10 ° steps from the normal direction to 50 ° on one side with respect to the film normal direction. The value is measured, and “KOBRA 21ADH” or “KOBRA WR” is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.

  In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by “KOBRA 21ADH” or “KOBRA WR” after changing its sign to negative.

In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (when there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following formulas (4) and (5).
Formula (4):

  The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In Equation (4), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. To express.

  Formula (5):

  In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optic axis, Rth (λ) is calculated by the following method.

  Rth (λ) is from −50 ° to + 50 ° with respect to the film normal direction with the in-plane slow axis (determined by “KOBRA 21ADH” or “KOBRA WR”) as the tilt axis (rotation axis). In each 10 ° step, light having a wavelength of λ nm is made incident from the inclined direction to measure the retardation value at 11 points, the measured retardation value, the assumed average refractive index, and the input film thickness value. Based on the above, “KOBRA 21ADH” or “KOBRA WR” is calculated.

In the above measurement, as the assumed value of the average refractive index, 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 the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting the assumed value of the average refractive index and the film thickness, “KOBRA 21ADH” or “KOBRA WR” calculates nx, ny, and nz. From this calculated nx, ny, nz, Nz = (nx−nz) / (nx−ny) is further calculated.

In the present invention, as the cellulose acylate film having a small optical anisotropy (Re, Rth), the retardation Re in the front direction and the retardation Rth in the film thickness direction at a wavelength of 630 nm are respectively expressed by the following formulas (1) and ( It is preferable to satisfy the range of 2).
Formula (1): −25 nm ≦ Rth (630) ≦ 25 nm,
Formula (2): 0 nm ≦ Re (630) ≦ 10 nm.

More preferably, the retardations Rth and Re satisfy the ranges of the following formulas (1-1) and (2-1), and particularly preferably the ranges of the following formulas (1-2) and (2-2). To meet.
Formula (1-1): −20 nm ≦ Rth (630) ≦ 20 nm,
Formula (2-1): 0 nm ≦ Re (630) ≦ 5 nm.
Formula (1-2): −15 nm ≦ Rth (630) ≦ 15 nm,
Formula (2-2): 0 nm ≦ Re (630) ≦ 2 nm.

  In the cellulose acylate film of the present invention, in the wavelength range of 400 nm to 700 nm, the Rth variation is preferably 25 nm or less and the Re variation is preferably 10 nm or less, the Rth variation is 20 nm or less and the Re variation. Is more preferably 5 nm or less, and it is particularly preferable that the variation of Rth is 15 nm or less and the variation of Re is 3 nm or less.

[Cellulose acylate]
[Cellulose acylate raw material cotton]
Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, softwood pulp) and the like, and any cellulose acylate obtained from any raw material cellulose can be used, optionally mixed. May be. Detailed descriptions of these raw material celluloses can be found in, for example, “Plastic Materials Course (17) Fibrous Resin” (Marusawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Publication Technical Report 2001-1745 ( 7 to 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.

[Substitution degree of cellulose acylate]
Next, the cellulose acylate of the present invention produced from the above-mentioned cellulose will be described.
The cellulose acylate of the present invention is obtained by acylating the hydroxyl group of cellulose, and the substituent can be any acetyl group having 2 carbon atoms to 22 carbon atoms. In the cellulose acylate of the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of substitution is measured by measuring the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose. Can be obtained. As a measuring method, it can carry out according to ASTM D-817-91.

  As described above, in the cellulose acylate of the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of acyl substitution with a hydroxyl group of cellulose is preferably 2.50 to 3.00. Further, the degree of substitution is preferably 2.75 to 3.00, and more preferably 2.85 to 3.00.

  Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an allyl group, and is not particularly limited. A mixture of They are, for example, alkyl carbonyl esters, alkenyl carbonyl esters, aromatic carbonyl esters, aromatic alkyl carbonyl esters, and the like of cellulose, each of which may further have a substituted group. These preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, i-butanoyl, t-butanoyl, cyclohexanecarbonyl, Examples include oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl groups. Among these, acetyl, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are preferable, and acetyl, propionyl and butanoyl are more preferable. The most preferred group is acetyl.

Among the acyl substituents substituted on the hydroxyl group of the cellulose, when it is substantially composed of at least two kinds of acetyl group / propionyl group / butanoyl group, the total substitution degree is 2.50 to 3.00 In addition, the optical anisotropy of the cellulose acylate film can be more suitably reduced. The degree of acyl substitution is more preferably 2.60 to 3.00, still more preferably 2.65 to 3.00.

  When the acyl substituent of the cellulose acylate is composed only of an acetyl group, the optical anisotropy of the cellulose acylate film is more suitably reduced when the total substitution degree is 2.50 to 2.95. it can.

[Degree of polymerization of cellulose acylate]
The degree of polymerization of cellulose acylate preferably used in the present invention is 18 in terms of viscosity average degree of polymerization.
In the cellulose acylate, 180 to 550 is more preferable, 180 to 400 is further preferable, and 180 to 350 is particularly preferable. If the degree of polymerization is not more than the upper limit, the viscosity of the cellulose acylate dope solution does not become too high, and film production by casting can be easily performed, which is preferable. If the degree of polymerization is equal to or greater than the lower limit, it is preferable because there is no inconvenience such as a decrease in strength of the produced film. The average degree of polymerization can be measured by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, “Journal of Textile Society”, Vol. 18, No. 1, pages 105-120, 1962). This method is also described in detail in JP-A-9-95538.

  Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

  Further, when the low molecular component of cellulose acylate is removed, the average molecular weight (degree of polymerization) increases, but the viscosity is lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent.

  In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized.

  When used in the production of the cellulose acylate film of the present invention, the moisture content of the cellulose acylate is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass. It is a cellulose acylate having a moisture content of not more than%. In general, cellulose acylate contains water and has a water content of about 2.5 to 5% by mass. In the present invention, in order to bring the water content of the cellulose acylate into a preferable range, it is necessary to dry, and the method is not particularly limited as long as the desired water content can be obtained. These cellulose acylates used in the present invention are the raw material cotton and the synthesis method of the invention association published technical bulletin No. 2001-1745 (issued March 15, 2001, Invention Association), pages 7-12. Are described in detail.

  The cellulose acylate used in the present invention can be used singly or as a mixture of two or more different types of cellulose acylates as long as the substituent, substitution degree, polymerization degree, molecular weight distribution and the like are within the above-mentioned ranges.

[Other additives to cellulose acylate]
In the cellulose acylate solution used in the present invention, in each preparation step, various additives (for example, plasticizers, deterioration inhibitors, Fine particles, etc.) can be added and these are described below. Further, the addition may be performed at any time in the dope preparation step, but may be performed by adding an additive to the final preparation step of the dope preparation step.

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the cellulose acylate film of the present invention. Examples of the fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. be able to. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / L or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / L or more, and more preferably 100 to 200 g / L or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, and are present as aggregates of primary particles in the film, and 0.1 to 3 on the film surface. An unevenness of 0.0 μm is formed. The secondary average particle size is preferably from 0.2 μm to 1.5 μm, more preferably from 0.4 μm to 1.2 μm, and most preferably from 0.6 μm to 1.1 μm. The primary and secondary particle sizes were determined by observing the particles in the film with a scanning electron microscope and determining the diameter of a circle circumscribing the particles as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

  The fine particles of silicon dioxide include, for example, “Aerosil R972”, “Aerosil R972V”, “Aerosil R974”, “Aerosil R812”, “Aerosil 200”, “Aerosil 200V”, “Aerosil 300”, “Aerosil R202”, “Aerosil”. Commercial products such as “OX50” and “Aerosil TT600” {manufactured by Nippon Aerosil Co., Ltd.} can be used. The fine particles of zirconium oxide are commercially available under the trade names of “Aerosil R976” and “Aerosil R811” {manufactured by Nippon Aerosil Co., Ltd.}, for example.

  Among these, “Aerosil 200V” and “Aerosil R972V” are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more, and reduce the turbidity of the optical film. This is particularly preferable because the effect of reducing the coefficient of friction is large while maintaining it.

In the present invention, in order to obtain a cellulose acylate film having particles having a small secondary average particle diameter, several methods are conceivable when preparing a fine particle dispersion. For example, a fine particle dispersion in which a solvent and fine particles are stirred and mixed is prepared in advance, and this fine particle dispersion is added to a small amount of separately prepared cellulose acylate solution and dissolved by stirring, and further mixed with the main cellulose acylate dope solution. There is a way. This method is a preferred preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, fine particles are added to this and dispersed with a disperser. This is used as a fine particle additive solution, and this fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer. There is also a method of mixing. Although the present invention is not limited to these methods, the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass. Most preferred is 20% by weight. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

[Plasticizer]
The cellulose acylate film of the present invention may contain a plasticizer. Although it does not specifically limit as a plasticizer which can be used, In a phosphate ester type | system | group, a triphenyl phosphate, a tricresyl phosphate, a cresyl diphenyl phosphate, an octyl diphenyl phosphate, a diphenyl biphenyl phosphate, a trioctyl phosphate, a tributyl phosphate, etc .; For acid ester systems, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, etc .; for glycolic acid ester systems, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl Than cellulose acylate of glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, etc. Or water used ones by itself or preferably in combination of two or more.

  In the cellulose acylate film of the present invention, in addition to the polymer and the ultraviolet absorber described above, various additives (for example, a plasticizer, an anti-degradation agent, a release agent, red, etc.) are used in each preparation step. External absorbents etc.) can be added and they can be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorber at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, Japanese Patent Application Laid-Open No. 2001-151901. Moreover, as an infrared absorber, what was described, for example in Unexamined-Japanese-Patent No. 2001-194522 can be used. Further, the amount of each material added is not particularly limited as long as the function is exhibited. Furthermore, when the cellulose acylate film is formed from multiple layers, the type and amount of additives in each layer may be different, and are described in, for example, Japanese Patent Application Laid-Open No. 2001-151902. This is a known technique. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

[Ratio of each compound addition]
In the cellulose acylate film of the present invention, the total amount of compounds having a molecular weight of 3000 or less is desirably 5 to 45% by mass with respect to the mass of cellulose acylate. More preferably, it is 10-40 mass%, More desirably, it is 15-30 mass%. As described above, these compounds include retardation regulators, ultraviolet absorbers, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, etc., and the molecular weight is 3000 or less. Desirably, 2000 or less is more desirable, and 1000 or less is further desirable. If the total amount of these compounds is equal to or greater than the lower limit value, the properties of the cellulose acylate alone will not be excessive. For example, the optical performance and physical strength are likely to fluctuate due to changes in temperature and humidity. Does not occur. Also, if the total amount of these compounds is less than or equal to the upper limit, problems such as exceeding the limit of compatibility of the compounds in the cellulose acylate film and depositing on the film surface to cause the film to become cloudy (crying out of the film) Therefore, these compounds are preferably used within the above range as a total amount. Furthermore, the addition timing may be added at any time in the dope preparation step, but as a final step of the dope preparation step, a step of adding an additive may be performed.

[Organic solvent for cellulose acylate solution]
In the present invention, it is preferable to produce a cellulose acylate film by a solvent cast method. In this method, the film is produced using a solution (dope) obtained by dissolving cellulose acylate in an organic solvent. The organic solvent preferably used as the main solvent of the present invention is preferably a solvent selected from esters having 3 to 12 carbon atoms, ketones, ethers, and halogenated hydrocarbons having 1 to 7 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the carbon number thereof may be within the specified range of the compound having any functional group.

  As described above, for the cellulose acylate film of the present invention, a chlorinated halogenated hydrocarbon may be used as a main solvent, and as described in JIII Journal of Technical Disclosure 2001-1745 (pages 12 to 16). In addition, a non-chlorine solvent may be used as the main solvent, and it is not particularly limited for the cellulose acylate film of the present invention.

  In addition, the solvent for the cellulose acylate solution and the film of the present invention is disclosed in the following patents, including its dissolution method, and is a preferred embodiment. They are, for example, JP 2000-95876 A, JP 12-95877 A, JP 10-324774 A, JP 8-152514 A, JP 10-330538 A, JP 9-95538 A. JP, 9-95557, JP 10-235664, JP 12-63534, JP 11-21379, JP 10-182853, JP 10-278056. JP-A-10-279702, JP-A-10-323853, JP-A-10-237186, JP-A-11-60807, JP-A-11-152342, JP-A-11-292988, This is described in, for example, Kaihei 11-60752 and JP-A-11-60752. According to these patents, not only the preferred solvent for the cellulose acylate in the present invention but also the physical properties of the solution and the coexisting substances to be coexisted are described, which is also a preferred embodiment in the present invention.

[Manufacturing process of cellulose acylate film]
[Dissolution process]
In the preparation of the cellulose acylate solution (dope solution) in the present invention, the dissolution method is not particularly limited, and may be room temperature dissolution, may be cooling dissolution method or high temperature dissolution method, and may be carried out in combination. Good. Regarding the preparation of the cellulose acylate solution in the present invention, and also the steps of solution concentration and filtration accompanying the dissolving step, the technical report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention) The manufacturing process described in detail on pages 22 to 25 is preferably used.

(Transparency of dope solution)
The transparency of a dope solution (hereinafter sometimes simply referred to as a dope), which is a cellulose acylate solution in the present invention, is desirably 85% or more. More preferably, it is 88% or more, and further preferably 90% or more. In the present invention, it is confirmed that various additives contained in the cellulose acylate dope solution are sufficiently dissolved. As a specific method for calculating the transparency of the dope, the dope solution was poured into a 1 cm square glass cell, and the absorbance at 550 nm was measured using a spectrophotometer “UV-3150” (manufactured by Shimadzu Corporation). Only the solvent was measured in advance as a blank, and the transparency of the dope was calculated from the ratio between the absorbance of the blank and the absorbance of the dope.

[Casting, drying, winding process]
Next, the manufacturing method of the film using the cellulose acylate solution (dope) in this invention is described. For the method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared in the dissolving machine (kettle) is temporarily stored in the storage kettle, and the foam contained in the dope is defoamed to make the final adjustment. The dope is sent from the dope discharge port to the pressurizing die through a pressurizing quantitative gear pump capable of feeding the dope with high accuracy by the number of revolutions, and then the dope is run endlessly from the die (slit) of the pressurizing die. The dope film (also referred to as a web) is peeled off from the metal support at the peeling point where the metal support is almost cast around the metal support. The resulting web is sandwiched between clips and held by a tenter while holding the width to be dried, and the resulting film is mechanically conveyed by a roll group of a drying device to finish drying, and a winder And roll up to a predetermined length in a roll. The combination of the tenter and the roll group dryer varies depending on the purpose. In a solution casting film forming method used for a functional protective film or a silver halide photographic light-sensitive material as an optical member for an electronic display as a main application of the cellulose acylate film of the present invention, a solution casting film forming apparatus is used. In addition, a coating apparatus is often added for surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, and a protective layer. These are described in detail on pages 25 to 30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention), and include casting (including co-casting). ), Metal support, drying, peeling, etc., and can be preferably used in the present invention.

The residual solvent content at any point on the casting film-forming process of the cellulose acylate film of the present invention is defined by the following mathematical formula (6).
Formula (6): (W _t −W ₀ ) × 100 / W ₀
W _t : Measurement mass of the actually measured dope film.
W ₀ : film mass when dried at 110 ° C. for 3 hours after completion of drying.
The residual solvent content at the peeling point is preferably in the range of 5 to 90% by mass, and the content of the poor solvent in the residual solvent is preferably in the range of 10 to 95% by mass.

[Stretching treatment of cellulose acylate film]
The retardation of the cellulose acylate film can be adjusted by stretching. The draw ratio is preferably 3 to 100%.

  As the stretching method, a known method can be used as long as it does not deviate from the above range, but tenter stretching is particularly preferably used from the viewpoint of in-plane uniformity. The cellulose acylate film of the present invention preferably has a width of at least 100 cm, the variation in the Re value of the total width is preferably ± 5 nm, and more preferably ± 3 nm. Further, the variation of the Rth value is preferably ± 10 nm, and more preferably ± 5 nm. Moreover, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

  In addition, the stretching process may be performed in the middle of the film forming process, or the raw film that has been formed and wound may be stretched. In the former case, stretching may be performed in a state containing a residual solvent, and the stretching can be preferably performed at a residual solvent amount of 2 to 30% by mass. At this time, it is preferable to stretch the film in the direction perpendicular to the longitudinal direction while conveying the film in the longitudinal direction so that the slow axis of the film is orthogonal to the longitudinal direction of the film.

  The stretching temperature can be selected appropriately depending on the amount of residual solvent and film thickness during stretching. When stretching in a state containing a residual solvent, it is preferable to dry after stretching. The drying method can be performed according to the method described in the film production.

[Film thickness]
10-120 micrometers is preferable, as for the thickness of the cellulose acylate film of this invention, 20-100 micrometers is more preferable, and 30-90 micrometers is more preferable. Moreover, the difference between the maximum value and the minimum value of the 1 m square film of the cellulose acylate film of the present invention, which is arbitrarily cut, is preferably 10% or less with respect to the average value of the thickness, and is 5% or less. It is more preferable that

[Physical evaluation of cellulose acylate film]
[Optical performance]
(Change in optical performance of film after high humidity treatment)
Regarding the change in optical performance of the cellulose acylate film of the present invention due to environmental changes, the amount of change in Re and Rth of a film treated at 60 ° C. and 90% RH for 240 hours is preferably 15 nm or less. More preferably, it is 12 nm or less, and further preferably 10 nm or less.

(Change in optical performance of film after high temperature treatment)
Further, the amount of change in Re and Rth of the film treated at 80 ° C. for 240 hours is preferably 15 nm or less. More preferably, it is 12 nm or less, and further preferably 10 nm or less.

(Humidity dependence of film Re and Rth)
The retardation Rth in the film thickness direction of the cellulose acylate film of the present invention preferably has a small change due to humidity. Specifically, the difference ΔRth between the Rth value at 25 ° C. and 10% RH represented by the following formula (7) and the Rth value at 25 ° C. and 80% RH is preferably 0 to 50 nm. More preferably, it is 0-40 nm, More preferably, it is 0-35 nm.
Formula (7): ΔRth = Rth _{10% RH} −Rth _{80% RH}

(In-plane variation of retardation of cellulose acylate film)
In the cellulose acylate film of the present invention, the Re and Rth values at a wavelength of 630 nm preferably satisfy the relationship represented by the following formula (8), and more preferably satisfy the relationship represented by the following formula (8-1).
Formula (8): | Re (630) max−Re (630) min | ≦ 5 and | Rth (630) max−Rth (630) min | ≦ 10
Formula (8-1): | Re (630) max−Re (630) min | ≦ 3 and | Rth (630) max−Rth (630) min | ≦ 5
{In the formula, Re (630) max and Rth (630) max are the maximum retardation values at a wavelength of 630 nm of an arbitrarily cut out 1 m square film, Re (630) min and Rth (630) min are the minimum at a wavelength of 630 nm It is a retardation value. }

(Photoelastic coefficient)
The photoelastic coefficient of the cellulose acylate film of the present invention is preferably 50 × 10 ⁻¹³ cm ² / dyne or less. It is more preferably 30 × 10 ⁻¹³ cm ² / dyne or less, and further preferably 20 × 10 ⁻¹³ cm ² / dyne or less. As a specific measuring method, a tensile stress is applied to the major axis direction of a 12 mm × 120 mm cellulose acylate film sample, and the retardation at that time is measured with an ellipsometer “M150” (manufactured by JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

(Haze of film)
The cellulose acylate film of the present invention preferably has a haze of 0.01 to 2%. Here, the haze can be measured as follows.
The haze is measured by measuring the cellulose acylate film sample 40 mm × 80 mm of the present invention at 25 ° C. and 60% RH with a haze meter (HGM-2DP, Suga Test Instruments) according to JIS K-6714.
A sample of 40 mm × 80 mm was measured according to JIS K6714 with a haze meter (HGM-2DP, Suga test machine) at 25 ° C. and 60% RH.

(Spectral characteristics, spectral transmittance)
A transmittance of a cellulose acylate film sample 13 mm × 40 mm was measured at a wavelength of 300 to 450 nm with a spectrophotometer “U-3210” {Hitachi, Ltd.} at 25 ° C. and 60% RH. The inclination width was obtained at a wavelength of 72% -5%. The limit wavelength was expressed by a wavelength of (gradient width / 2) + 5%. The absorption edge is represented by a wavelength having a transmittance of 0.4%. From this, the transmittance | permeability of 380 nm and 350 nm was evaluated.
In the cellulose acylate film of the present invention, the spectral transmittance at a wavelength of 400 nm is preferably 45% or more and 95% or less, and the spectral transmittance at a wavelength of 350 nm is preferably 10% or less.

[Physical properties]
(Glass glass transition temperature Tg)
The measurement of the glass transition temperature (Tg) was carried out using a differential scanning calorimeter “DSC2910” (TA Instruments Inc.) from a room temperature to 200 ° C. at a rate of temperature increase / decrease of 5 ° C./min. Calorimetric measurement was performed, and the glass transition temperature (Tg) was calculated.
The glass transition temperature (Tg) of the cellulose acylate film of the present invention is preferably 80 to 165 ° C. From the viewpoint of heat resistance, Tg is more preferably 100 to 160 ° C, and particularly preferably 110 to 150 ° C.

(Equilibrium moisture content of film)
The equilibrium moisture content of the cellulose acylate film of the present invention is 25 ° C., regardless of the film thickness, so as not to impair the adhesion with a water-soluble polymer such as polyvinyl alcohol when used as a protective film of a polarizing plate. The equilibrium moisture content at 80% RH is preferably 0 to 4%. It is more preferably 0.1 to 3.5%, and particularly preferably 1 to 3%. If the equilibrium moisture content is 4% or less, it is preferable that the dependency of retardation due to humidity change does not become too large when used as a support for an optical compensation film.
The water content was measured by using a cellulose acylate film sample of 7 mm × 35 mm according to the present invention with a moisture meter, a sample drying apparatus “CA-03” and “VA-05” (both manufactured by Mitsubishi Chemical Corporation) and Karl Fischer. Measured by the method. It was calculated by dividing the amount of water (g) by the sample mass (g).

(Water permeability of film)
The moisture permeability of the film is determined by measuring the film under conditions of 60 ° C. and 95% RH based on JIS Z-0208 and converting it to a film thickness of 80 μm.
The moisture permeability decreases as the thickness of the cellulose acylate film increases, and increases as the thickness decreases. Therefore, it is necessary to convert the sample of any film thickness to a standard of 80 μm. The film thickness can be converted according to the following mathematical formula (9).
Formula (9): Moisture permeability in terms of 80 μm = measured moisture permeability × measured film thickness (μm) / 80 (μm).

The measurement method of water vapor transmission rate is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294 “Measurement of vapor permeation amount (mass method, thermometer method, vapor pressure method, adsorption amount method) Can be applied.
Specifically, the cellulose acylate film sample 70 mmφ of the present invention was conditioned at 60 ° C. and 95% RH for 24 hours, and the moisture permeability test apparatus “KK-709007” {manufactured by Toyo Seiki Co., Ltd.} The water content per unit area was calculated (g / m ² ) according to Z-0208, and determined according to the following formula (10).
Formula (10): Moisture permeability = mass after humidity control-mass before humidity control

The moisture permeability of the cellulose acylate film of the present invention is preferably 400 to 2000 g / m ² · 24 h. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. If the moisture permeability is within 2000 g / m ² · 24 h, there will be no inconvenience such as the absolute value of the humidity dependence of the Re value and Rth value of the film exceeding 0.5 nm /% RH. An optical compensation film obtained by laminating an optically anisotropic layer on the cellulose acylate film is also preferable because the absolute value of the humidity dependence of the Re value and Rth value does not exceed 0.5 nm /% RH. Furthermore, it is preferable that an optical compensation sheet or a polarizing plate produced using such a film is incorporated in a liquid crystal display device because it does not cause a change in color or a decrease in viewing angle. On the other hand, if the moisture permeability of the cellulose acylate film is 400 g / m ² · 24 h or more, the cellulose acylate film prevents drying of the adhesive when the polarizer is attached to both sides of the polarizer. This is preferable because it exhibits excellent adhesion.

(Dimensional change of film)
The dimensional stability of the cellulose acylate film of the present invention is as follows: dimensional change rate after standing for 24 hours under conditions of 60 ° C. and 90% RH (high humidity), and conditions of 90 ° C. and 5% RH It is preferable that the dimensional change rate after standing for 24 hours (high temperature) is 0.5% or less.
More preferably, it is 0.3% or less, More preferably, it is 0.15% or less.

As a specific measurement method, two cellulose acylate film samples 30 mm × 120 mm were prepared, conditioned at 25 ° C. and 60% RH for 24 hours, and both ends with an automatic pin gauge {manufactured by Shinto Kagaku Co., Ltd.}. 6 mmφ holes were drilled at 100 mm intervals to obtain the original punch spacing (L ₀ ). After one sample was treated at 60 ° C. and 90% RH for 24 hours, the dimension of the punch interval (L ₁ ) was measured, and the other sample was treated at 90 ° C. and 5% RH for 24 hours. The dimension (L ₂ ) of the punch interval was measured. In all the measurement of the interval, measurement was made to the minimum scale 1/1000 mm, and the dimensional change rate was obtained according to the following formulas (11) and (12).
Formula (11): Dimensional change rate of 60 ° C. and 90% RH (high humidity) = {| L ₀ −L ₁ | / L ₀ } × 100,
Formula (12): Dimensional change rate of 90 ° C., 5% RH (high temperature) = {| L ₀ −L ₂ | / L ₀ } × 100.

(Elastic modulus of film)
Elastic modulus of the cellulose acylate film of the present invention is preferably 200 to 500 kgf / mm ^2, more preferably 240~470kgf / mm ^2, more preferably from 270~440kgf / mm ^2. As a specific measurement method, a universal tensile tester “STM T50BP” manufactured by Toyo Baldwin Co., Ltd. was used, and the stress at 0.5% elongation was measured in a 23 ° C., 70% RH atmosphere at a tensile rate of 10% / min. The elastic modulus was obtained.

[Film surface properties]
The surface of the cellulose acylate film of the present invention has an arithmetic average roughness (Ra) of surface irregularities of the film based on JIS B0601-1994 of 0.1 μm or less and a maximum height (Ry) of 1 μm or less. preferable. Preferably, the arithmetic average roughness (Ra) is 0.05 μm or less and the maximum height (Ry) is 0.5 μm or less, and most preferably, the arithmetic average roughness (Ra) is 0.03 μm or less, and the maximum The height (Ry) is 0.3 μm or less. The concave and convex shapes on the film surface can be evaluated by an atomic force microscope (AFM).

[Compound retention of film]
In the cellulose acylate film of the present invention, retention of various compounds such as a plasticizer and an ultraviolet absorber added to the film is required.

(Compound retention after film high temperature and high humidity treatment)
The cellulose acylate film of the present invention preferably has a mass change of 0 to 5% when left for 48 hours under conditions of 80 ° C. and 90% RH. More preferably, it is 0-3 mass%, More preferably, it is 0-2%.

(Method for evaluating holdability)
A cellulose acylate film sample was cut to a size of 10 cm × 10 cm, and the mass after being left for 24 hours in an atmosphere of 23 ° C. and 55% RH was measured. Then, the conditions were 80 ± 5 ° C. and 90 ± 10% RH. And left for 48 hours. The surface of the sample after the treatment was lightly wiped, the mass after being left for 1 day at 23 ° C. and 55% RH was measured, and the retention of the compound after the high temperature and high humidity treatment was calculated according to the following formula (13).
Formula (13): Compound retention (mass%) after high-temperature and high-humidity treatment = {(mass before leaving−mass after standing) / mass before standing} × 100

[Mechanical properties of film]
(curl)
The curl value in the width direction of the cellulose acylate film of the present invention is preferably −10 / m to + 10 / m.
In the cellulose acylate film of the present invention, the surface treatment described later, an optically anisotropic layer, a rubbing treatment, an alignment film, and an optically anisotropic layer are coated and bonded. When the curl value in the width direction of the film is within the above range, the film handling is not hindered and the film is not cut off. In addition, at the edge and center of the film, the film comes into strong contact with the transport roll and generates dust, increasing the adhesion of foreign matter onto the film, and the frequency of point defects and coating streaks on the optical compensation film exceeds the allowable value. There is no problem of exceeding. Furthermore, curling within the above range is preferable because it can reduce color spot failure that is likely to occur when an optically anisotropic layer is installed, and can prevent bubbles from entering when a polarizer is bonded.

  The curl value can be measured according to a measurement method (ANSI / ASCPH1.29-1985) defined by the American National Standards Institute. For example, it can be measured with a curl plate displaying the radius of curvature.

(Tear strength)
The tear strength of the film is determined based on the tear test method of JIS K7128-2: 1998. After adjusting the humidity of a sample piece 50 mm × 64 mm under the conditions of 25 ° C. and 65% RH for 2 hours, a light load tear strength tester (Toyo It can be measured using Seiki Seisakusho. (Elmendorf tearing method)
The tear strength of the cellulose acylate film of the present invention is preferably 2 g or more when the film thickness of the film of the present invention is in the range of 20 to 80 μm. More preferably, it is 5-25g, Furthermore, it is 6-25g. Moreover, 8 g or more is preferable at 60 micrometer conversion, More preferably, it is 8-15g.

[Residual solvent amount of film]
The cellulose acylate film of the present invention is preferably dried under the conditions that the residual solvent amount relative to the film is in the range of 0.01 to 1.5% by mass. More preferably, it is 0.01-1.0 mass%. When the cellulose acylate film of the present invention is used as a transparent support such as an antireflection film or an optical compensation film, curling can be suppressed by setting the residual solvent amount to 1.5% or less. More preferably, it is 1.0 mass% or less. This is presumably because free deposition becomes smaller by reducing the amount of residual solvent during film formation by the casting method (solvent cast method) using the dope described above.

[Hygroscopic expansion coefficient of film]
The measurement of the hygroscopic expansion coefficient was a value L _{80 obtained} by measuring the dimensions of a film left at 25 ° C. and 80% RH for 2 hours or more using “Pin Gauge EF-PH” (Mitutoyo Co., Ltd.), 25 ° C., the value L ₁₀ Metropolitan as measured in the same manner the dimensions of the left film over 2 hours under 10% RH, were determined by the following equation (14).
Formula (14): Hygroscopic expansion coefficient = (L ₁₀ −L ₈₀ ) / L ₁₀ / (80−10) [unit: (% RH) ⁻¹ ]

The hygroscopic expansion coefficient indicates a change rate of the sample length when the relative humidity is changed at a constant temperature.
The hygroscopic expansion coefficient of the cellulose acylate film of the present invention is preferably 30 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 × 10 ⁻⁵ /% RH or less. Further, the hygroscopic expansion coefficient is preferably small, but usually a value of 1.0 × 10 ⁻⁵ /% RH or more. Further, it is preferable that the hygroscopic expansion coefficient is substantially equal between the machine direction and the vertical direction.

[surface treatment]
The cellulose acylate film can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. For the surface treatment of the cellulose acylate film, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used.

The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention), and are preferably used in the present invention. be able to.

(Saponification treatment)
One effective means of surface treatment when the cellulose acylate film of the present invention is used as a transparent protective film of a polarizing plate is an alkali saponification treatment.

Hereinafter, the alkali saponification treatment will be specifically described.
The alkali saponification treatment of the cellulose acylate film is preferably performed in a cycle in which the film surface is immersed in an alkali solution, neutralized with an acidic solution, washed with water and dried. Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the concentration of hydroxide ions is preferably in the range of 0.1 to 5.0 mol / L, and preferably 0.5 to 4.0 mol / L. More preferably, it is in the range. The alkaline solution temperature is preferably in the range of room temperature to 90 ° C, more preferably in the range of 40 to 70 ° C.

  In the cellulose acylate film of the present invention, the contact angle of the film surface after the alkali saponification treatment is preferably 55 ° or less. More preferably, it is 50 ° or less, and further preferably 45 ° or less. The contact angle evaluation method can be used as an evaluation of hydrophilicity / hydrophobicity by an ordinary method in which a water droplet having a diameter of 3 mm is dropped on the surface of the film after the alkali saponification treatment and the angle formed by the film surface and the water droplet is determined.

  In general, the surface energy of a solid can be determined by a contact angle method, a wet heat method, and an adsorption method as described in “Basics and Applications of Wetting” (issued by Realize 1989.12.10). In the case of the cellulose acylate film of the present invention, it is preferable to use a contact angle method. Specifically, two kinds of solutions having known surface energies are dropped on a cellulose acylate film, and at the intersection of the surface of the droplet and the surface of the film, the angle formed between the tangent line drawn on the droplet and the film surface, The surface angle of the film can be calculated by defining the angle containing the droplet as the contact angle.

(Changes in Re and Rth values before and after saponification of the film surface)
In the cellulose acylate film of the present invention, the change in Re and Rth values at a wavelength of 630 nm before and after saponifying the film surface with an alkaline solution preferably satisfies the relationship of the following formula (15). It is more preferable to satisfy the relationship of -1), and it is more preferable to satisfy the relationship of Formula (15-2).
Formula (15): | Re (630) F−Re (630) S | ≦ 10 and | Rth (630) F−Rth (630) S | ≦ 20
Formula (15-1): | Re (630) F−Re (630) S | ≦ 8 and | Rth (630) F−Rth (630) S | ≦ 15,
Formula (15-2): | Re (630) F−Re (630) S | ≦ 5 and | Rth (630) F−Rth (630) S | ≦ 10.
In the above formula, Re (630) F represents Re at a wavelength of 630 nm before saponification with an alkaline solution, Re (630) S represents Re at a wavelength of 630 nm after saponification with an alkaline solution, and Rth (630) F represents an alkaline solution. Rth and Rth (630) S at a wavelength of 630 nm before saponification with γ represent Rth at a wavelength of 630 nm after saponification with an alkaline solution.
If it is in said range, when it applies to a polarizing plate, an optical compensation film, and a liquid crystal display device, it is inferior to the optical performance of a protective film, and there is no light leakage, and it is preferable.

  The specific alkali saponification treatment in the present invention means that a 10 cm × 10 cm film sample is immersed in a 1.5 mol / L sodium hydroxide aqueous solution for 2 minutes at 30 ° C. unless otherwise specified. The step of neutralizing with 0.05 mol / L sulfuric acid solution, washing in a water bath at room temperature, and drying at 100 ° C.

[Light resistance]
As an index of light durability of the cellulose acylate film of the present invention, a change in Rth value of a film irradiated with super xenon light for 200 hours was measured. Xenon light irradiation is a cellulose acylate film alone, and super xenon weather meter “SX-75” (Suga Test Instruments Co., Ltd., 60 ° C., 50% RH condition) with xenon light at 250,000 Lx for 200 hours. Irradiated. After the elapse of a predetermined time, the film was taken out of the thermostatic bath, and after humidity adjustment was performed in the same manner as described above, the film was measured.

Alternatively, it is also possible to use a color difference ΔE ^* a ^* b ^* as an index of light endurance, a super xenon light was irradiated under the same conditions as described above, that the front and rear of the color difference ΔE ^* a ^* b ^* is 20 or less Is preferred. More preferably, it is 18 or less, and it is still more preferable that it is 15 or less.

For the measurement of the color difference, “UV3100” {manufactured by Shimadzu Corporation} was used. The method of measurement is that the film is conditioned at 25 ° C. and 60% RH for 2 hours or more, then color measurement of the film before xenon light irradiation is performed, and the initial values (L ₀ ^* , a ₀ ^* , b ₀ ^* ) are set. Asked. Then, the film itself was irradiated with xenon light under the conditions of 60 ° C. and 50% RH. After a predetermined time, the film was taken out of the thermostatic bath, adjusted to 25 ° C. and 60% RH for 2 hours, and then again colored. Measurement was carried out to determine values after irradiation (L ₁ ^* , a ₁ ^* , b ₁ ^* ). From these, the color difference ΔE ^* a ^* b ^* was determined according to the following formula (16).
Formula (16): ΔE ^* a ^* b ^* = [(L ₀ ^* −L ₁ ^* ) ² + (a ₀ ^* −a ₁ ^* ) ² + (b ₀ ^* −b ₁ ^* ) ² ] ^1/2 .

  In the above test, super xenon light was irradiated under the same conditions as described above, and a cellulose acylate film before and after irradiation was extracted with a solvent such as tetrahydrofuran to extract a compound such as a retardation regulator, and then high performance liquid chromatography. Detection and quantification were carried out at. In addition, you may use the carbon arc irradiation which is the same accelerated test for the light resistance test in this invention.

<Uses of cellulose acylate film>
[Optical use]
The cellulose acylate film of the present invention is applied to optical uses and photographic light-sensitive materials as its uses. In particular, it is preferably used for a liquid crystal display device as an optical application. The liquid crystal display device is generally configured by disposing a liquid crystal cell in which liquid crystal is supported between two electrode substrates, and two polarizing plates disposed on both sides thereof, and the cellulose acylate film of the present invention includes: It is more preferable to use it for a liquid crystal display device as a protective film for a polarizing plate or by providing a functional layer described later. As these liquid crystal display devices, TN, IPS, FLC, AFLC, OCB, STN, ECB, VA and HAN are preferable.

[Functional layer]
When the cellulose acylate film of the present invention is used for the optical application as described above, various functional layers can be provided on the film. Examples of the functional layer include an antistatic layer, a cured resin layer (transparent hard coat layer), an antireflection layer, an easy adhesion layer, an antiglare layer, an optical compensation layer, an alignment layer, a liquid crystal layer, and the like. Surfactants, slip agents, matting agents, fillers, dyes, and the like can be added to the layer. Examples of the functional layer applicable to the transparent film of the present invention include those described in pages 32 to 45 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is done.
Moreover, when using as another use, you may provide functional layers, such as a subbing layer and a back layer, in a transparent film.

[Application (Polarizing plate)]
The use of the cellulose acylate film of the present invention will be described.
The cellulose acylate film of the present invention is particularly useful as a polarizing plate protective film. When using as a polarizing plate protective film, the preparation method of a polarizing plate is not specifically limited, It can produce by a general method. The obtained cellulose acylate film has a method in which the surface is treated with an alkali and bonded to both sides of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution or the like. . Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed.

  Examples of the adhesive used to bond the protective film treated surface and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like.

The polarizing plate is composed of a polarizer and a protective film that protects both surfaces of the polarizer, and further includes a protective film on one surface of the polarizing plate and a separate film on the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protective film is bonded for the purpose of protecting the surface of the polarizing plate, used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate, and the separate film is bonded to the liquid crystal cell. It is used for the purpose of covering the layer, and is used on the surface side where the polarizing plate is bonded to the liquid crystal plate.

  In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates, but the polarizing plate protective film to which the cellulose acylate film of the present invention is applied is excellent in any position. Sex is obtained. In particular, the polarizing plate protective film on the outermost surface of the display side of the liquid crystal display device is provided with a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like. preferable.

[Application (Optical compensation film)]
The cellulose acylate film of the present invention can be used in various applications, and is particularly effective when used as a support for an optical compensation film of a liquid crystal display device. The optical compensation film is generally used for a liquid crystal display device and refers to an optical material that compensates for a retardation, and is synonymous with a retardation plate, an optical compensation sheet, and the like. The optical compensation film has birefringence and is used for the purpose of removing the color of the display screen of the liquid crystal display device or improving the viewing angle characteristics.

  Therefore, when the cellulose acylate film of the present invention is used for an optical compensation film of a liquid crystal display device, Re and Rth of the optically anisotropic layer used in combination are Re = 0 to 200 nm and | Rth | = 0 to 400 nm. Any optically anisotropic layer may be used as long as it is within this range.

  The optical performance and driving method of the liquid crystal cell of the liquid crystal display device in which the cellulose acylate film of the present invention is used are not particularly limited, and any optical anisotropic layer required as an optical compensation film is used in combination. be able to. The optically anisotropic layer used in combination may be formed from a composition containing a liquid crystalline compound or may be formed from a polymer film having birefringence.

(Optically anisotropic layer containing liquid crystalline compound)
When using an optically anisotropic layer containing a liquid crystalline compound, the liquid crystalline compound is preferably a discotic liquid crystalline compound or a rod-shaped liquid crystalline compound.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds that can be used in the present invention include various documents [C. Destrade et al., “Mol. Crysr. Liq. Cryst.”, 71, p. 111 (1981); edited by The Chemical Society of Japan, “Quarterly Chemistry Review”, No. 22, “Chemicals of Liquid Crystals”, Chapter 5, Chapter 10, Section 2 (1994); Kohne et al., “Angew. Chem. Soc. Chem. Comm.”, P. 1794 (1985); Zhang et al., “J. Am. Chem. Soc.”, 116, p. 2655 (1994)].

  In the optically anisotropic layer, the molecules of the discotic liquid crystalline compound are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. The polymerization of discotic liquid crystalline compounds is described in JP-A-8-27284. In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. 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. JP-A-2001-4387 discloses a discotic liquid crystalline compound having a polymerizable group.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds that can be used in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, and cyano-substituted compounds. Phenyl pyrimidines, alkoxy substituted phenyl pyrimidines, phenyl dioxanes, tolanes and alkenyl cyclohexyl benzonitriles are included. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used.

  In the optically anisotropic layer, the rod-like liquid crystal compound molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. Examples of polymerizable rod-like liquid crystal compounds that can be used in the present invention include “Makromol. Chem.”, 190, 2255 (1989), “Advanced Materials”, 5, 107 (1993), USA. Patent Nos. 4,683,327, 5,622,648, 5,770,107, WO95 / 22586, 95/24455, 97/00600, 98/98. No. 23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, JP-A-2001-328773, etc. Are included.

(Optically anisotropic layer made of polymer film)
As described above, the optically anisotropic layer in the present invention may be formed from a polymer film. The polymer film is formed from a polymer that can exhibit optical anisotropy. Examples of such polymers include polyolefins (eg, polyethylene, polypropylene, norbornene-based polymers), polycarbonates, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylic acid esters, polyacrylic acid esters, and cellulose esters (eg, cellulose tria). Sate, cellulose diacetate, etc.). Moreover, you may use the copolymer or polymer mixture of these polymers.

  The optical anisotropy of the polymer film is preferably obtained by stretching. The stretching is preferably uniaxial stretching or biaxial stretching. Specifically, longitudinal uniaxial stretching using a difference in peripheral speed between two or more rolls, tenter stretching for grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching in combination of these is preferable. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 500 μm, and most preferably 40 to 100 μm.

  Further, as the polymer film forming the optically anisotropic layer, at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone is used. A method in which a solution in which is dissolved in a solvent is applied to a substrate and the solvent is dried to form a film can also be preferably used.

  At this time, the polymer film and the base material are stretched to develop optical anisotropy, and a method of using as an optically anisotropic layer can also be preferably used. In this case, the cellulose acylate film of the present invention is used in this case. It can preferably be used as a base material. Moreover, after preparing these polymer films on another base material, and peeling the polymer film from a base material, it bonds with the cellulose acylate film of this invention, and is used as an optically anisotropic layer. It is also preferable to use it. In this method, the thickness of the polymer film can be reduced, and the thickness is preferably 50 μm or less, and more preferably 1 to 20 μm.

[Configuration of general liquid crystal display device]
When the cellulose acylate film is used for the optical compensation film, the transmission axis of the polarizing element and the slow axis of the optical compensation film made of the cellulose acylate film may be arranged at any angle. The liquid crystal display device includes a liquid crystal cell in which liquid crystal is supported between two electrode substrates, two polarizing elements disposed on both sides thereof, and at least one sheet between the liquid crystal cell and the polarizing element. The optical compensation film is arranged.

  The liquid crystal layer of the liquid crystal cell is usually formed by sealing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.

(Types of liquid crystal display devices)
The cellulose acylate film of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically Liquid BTS). Various display modes such as ECB (Electrically Controlled Birefringence) and HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. The cellulose acylate film of the present invention is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

(TN type liquid crystal display device)
The cellulose acylate film of the present invention may be used as a support for an optical compensation film of a TN type liquid crystal display device having a TN mode liquid crystal cell or as a protective film for a polarizing plate. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. The optical compensation film used in the TN liquid crystal display device is described in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. Further, it is described in a paper by Mori et al. ("Jpn. J. Appl. Phys.", Volume 36 (1997), p. 143 and p. 1068).

(STN type liquid crystal display device)
The cellulose acylate film of the present invention may be used as a support for an optical compensation film of an STN type liquid crystal display device having an STN mode liquid crystal cell. In general, in the STN type liquid crystal display device, the molecules of the rod-like liquid crystalline compound in the liquid crystal cell are twisted in the range of 90 to 360 °, and the refractive index anisotropy (Δn) of the rod-like liquid crystalline compound and the cell gap ( The product (Δn · d) with d) is in the range of 300 to 1500 nm. The optical compensation film used for the STN type liquid crystal display device is described in JP-A No. 2000-105316.

(VA type liquid crystal display device)
The cellulose acylate film of the present invention may be used as a support for an optical compensation film of a VA liquid crystal display device having a VA mode liquid crystal cell. It is preferable that the retardation value Re of the optical compensation film used in the VA liquid crystal display device is 0 to 150 nm and the retardation value Rth is 70 to 400 nm. Retardation value Re is 20 to 7
More preferably, it is 0 nm. When two optically anisotropic polymer films are used in the VA liquid crystal display device, the retardation value Re of the film is preferably 70 to 250 nm. When a single optically anisotropic polymer film is used for the VA liquid crystal display device, the retardation value Rth of the film is preferably 150 to 400 nm. The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576.

(IPS liquid crystal display device and ECB liquid crystal display device)
The cellulose acylate film of the present invention is particularly advantageous as a support for an optical compensation film of an IPS liquid crystal display device and an ECB liquid crystal display device having a liquid crystal cell of IPS mode and ECB mode, or as a protective film for a polarizing plate. Used. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and in a state where no voltage is applied, the liquid crystal molecules are aligned parallel to the substrate surface to display black. In these embodiments, the polarizing plate using the cellulose acylate film of the present invention contributes to the improvement of the color tone, the expansion of the viewing angle, and the improvement of the contrast. In this aspect, the cellulose acylate film of the present invention is applied to the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing plate among the protective films of the polarizing plate above and below the liquid crystal cell. The polarizing plate used is preferably used at least on one side of the liquid crystal cell. More preferably, an optically anisotropic layer is disposed between the protective film of the polarizing plate and the liquid crystal cell, and the retardation value of the disposed optically anisotropic layer is twice the value of Δn · d of the liquid crystal layer. It is preferable to set as follows.

(OCB type liquid crystal display device and HAN type liquid crystal display device)
The cellulose acylate film of the present invention is also advantageously used as a support for an optical compensation film of an OCB type liquid crystal display device having an OCB mode liquid crystal cell or a HAN type liquid crystal display device having a HAN mode liquid crystal cell. In an optical compensation film used for an OCB type liquid crystal display device or a HAN type liquid crystal display device, there is no direction in which the absolute value of retardation is minimized, neither in the plane of the optical compensation film nor in the normal direction. preferable. The optical properties of the optical compensation film used in the OCB type liquid crystal display device or HAN type liquid crystal display device are also the optical properties of the optically anisotropic layer, the optical properties of the support, and the arrangement of the optically anisotropic layer and the support. Determined by. An optical compensation film used for an OCB type liquid crystal display device or a HAN type liquid crystal display device is described in JP-A-9-197397. Also, Mori et al., “Jpn. J. Appl. Phys.”, 38 (1999) p. 2837}.

(Reflective liquid crystal display)
The cellulose acylate film of the present invention is also advantageously used for an optical compensation film of a TN type, STN type, HAN type, GH (Guest-Host) type reflective liquid crystal display device. These display modes have been well known since ancient times. The TN type reflection type liquid crystal display device is described in JP-A-10-123478, International Publication No. 98/48320, and Japanese Patent No. 3022477. The optical compensation film used in the reflective liquid crystal display device is described in International Publication No. 00/65384 pamphlet.

(Other liquid crystal display devices)
The cellulose acylate film of the present invention is also advantageously used as a support for an optical compensation film of an ASM type liquid crystal display device having a liquid crystal cell in an ASM (axially aligned microcell) mode. The ASM mode liquid crystal cell is characterized in that the thickness of the cell is maintained by a resin spacer whose position can be adjusted. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in a paper by Kume et al. {Kume et al. , "SID 98 Digest 1089" (1998)}.

[Hard coat film, antiglare film, antireflection film]
The cellulose acylate film of the present invention can be preferably applied to a hard coat film, an antiglare film and an antireflection film. For the purpose of improving the visibility of flat panel displays such as LCD, PDP, CRT, EL, etc., one or both of a hard coat layer, an antiglare layer and an antireflection layer on one side or both sides of the cellulose acylate film of the present invention or their All can be granted. Preferred embodiments of such an antiglare film and antireflection film are described in detail in pages 54 to 57 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). The cellulose acylate film of the present invention can be preferably used.

[Photographic film support]
Furthermore, the cellulose acylate film of the present invention can be applied as a support for silver halide photographic light-sensitive materials, and various materials and formulations described in the patent specifications of the photographic light-sensitive materials, and further processing methods can be applied. . Regarding these techniques, Japanese Patent Application Laid-Open No. 2000-105445 discloses details regarding color negatives, and the cellulose acylate film of the present invention is preferably used. Further, application as a support for a color reversal silver halide photographic light-sensitive material is also preferable, and various materials, formulations and processing methods described in JP-A No. 11-282119 can be applied.

[Transparent substrate of liquid crystal cell]
Since the cellulose acylate film of the present invention has an optical anisotropy close to zero and excellent transparency, it is an alternative to the liquid crystal cell glass substrate of a liquid crystal display device, that is, as a transparent substrate that encloses a driving liquid crystal. Can also be used.

Since the transparent substrate enclosing the liquid crystal needs to be excellent in gas barrier properties, a gas barrier layer may be provided on the surface of the cellulose acylate film of the present invention as necessary. Although the form and material of the gas barrier layer are not particularly limited, SiO ₂ or the like is vapor-deposited on at least one surface of the cellulose acylate film of the present invention, or a relative gas barrier such as vinylidene chloride polymer or vinyl alcohol polymer. A method of providing a high polymer coating layer can be considered, and these can be used as appropriate.

  In order to use as a transparent substrate for enclosing liquid crystal, a transparent electrode for driving the liquid crystal by applying a voltage may be provided. Although a transparent electrode is not specifically limited, It can form by laminating | stacking a metal film, a metal oxide film, etc. on the at least single side | surface of the cellulose acylate film of this invention. Among these, a metal oxide film is preferable from the viewpoint of transparency, conductivity, and mechanical characteristics, and an indium oxide thin film mainly containing tin oxide and containing 2 to 15% by mass of zinc oxide can be preferably used. Details of these techniques are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2001-125079 and 2000-227603.

  Examples of the present invention will be given below, but the present invention is not limited thereto.

<Production of cellulose acylate film>
[Preparation of acrylic polymer]
Preparation Example 1
A polymer (P-11) was prepared by a known synthesis method. Hereinafter, this polymer is referred to as polymer (P-11-1) (mass average molecular weight 5,000) and polymer (P-11-2) (mass average molecular weight 1,800) in terms of mass average molecular weight. Polymers (P-11-1) and (P-11-2) were each dissolved in ethyl acetate, and then added to hexane, and the resulting precipitate was collected by filtration. By repeating the crystallization step, modified polymers with different residual ethylenically unsaturated monomer contents shown in the table below were obtained. The monomer content was measured by gas chromatography.

[Preparation of cellulose acylate film]
Comparative Example 1-1
[Preparation of Cellulose Acylate Stock Solution (CAL-1)]
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acylate solution stock solution (CAL-1).

{Composition of cellulose acylate stock solution (CAL-1)}
Cellulose acylate 100 parts by mass Acetyl substitution degree 2.86, average polymerization degree 310
Methylene chloride (first solvent) 402 parts by mass Methanol (second solvent) 60 parts by mass

[Preparation of matting agent solution (ML-1)]
The following composition was put into a disperser and stirred to dissolve each component to prepare a matting agent solution (ML-1).

{Matting agent solution (ML-1) composition}
Silica particle dispersion (average particle size 16 nm) 10.0 parts by mass
"AEROSIL R972", Nippon Aerosil Co., Ltd. Methylene chloride (first solvent) 76.3 parts by weight Methanol (second solvent) 3.4 parts by weight Cellulose acylate stock solution (CAL-1) 10.3 parts by weight

[Preparation of Acrylic Polymer Solution A]
The following composition was put into another mixing tank, stirred while heating to dissolve each component, and a solution A containing the polymer of the present invention was prepared.

(Acrylic polymer solution A composition)
Ultraviolet absorber (UV-23L) 2.0 parts by mass Ultraviolet absorber (UV-28L) 2.0 parts by mass Polymer (P-11-1A) 49.3 parts by mass Methylene chloride (first solvent) 58.4 Parts by mass ethanol (second solvent) 8.7 parts by mass cellulose acylate stock solution (CAL-1) 12.8 parts by mass

[Production of Cellulose Acylate Film (101)]
Cellulose acylate solution stock solution (CAL-1) 94.6 parts by mass, matting agent solution (ML-1) 1.3 parts by mass, cellulose acylate 100 parts by mass, UV absorber (UV-23L) and UV absorber The acrylic polymer solution A is mixed so that (UV-28L) is 0.6 parts by mass and the polymer (P-11-1A) of the present invention is 20 parts by mass, and is sufficiently stirred while heating. And each component was melt | dissolved and dope (DP1-1) was prepared. The obtained dope (DP1-1) was cast using a band casting machine. After stripping off at a residual solvent amount of 26% by mass, the film was dried at 140 ° C. for 40 minutes to prepare a cellulose acylate film sample (101) having a thickness of 80 μm.

Examples 1-1 to 1-7 and Comparative Examples 1-2 to 1-3
[Production of Cellulose Acylate Films (102) to (110)]
In preparation of the cellulose acylate film (101) of Comparative Example 1-1, instead of using the acrylic polymer solution A, the type and amount of the modified polymer were adjusted so that the composition shown in Table 3 was obtained. Acrylic polymer solutions A ′, B to F, B ′ and F ′ were prepared and used, respectively, and the same as in Comparative Example 1-1 except that the type and amount of the UV absorber were changed as necessary. Thus, dopes (DP1-2 to DP1-10) were prepared, and cellulose acylate film samples (102) to (110) were prepared using these dopes. The film thicknesses of the cellulose acylate film samples (102) to (110) were all in the range of 79.5 to 80.5 μm. In the samples (101) to (110), the difference between the maximum value and the minimum value of the 1 m square film cut out arbitrarily was within 5% of the average thickness.

Comparative Examples 1-4 to 1-5
[Production of Cellulose Acylate Films (111) to (112)]
In preparation of the cellulose acylate film (101) of Comparative Example 1-1, a known plasticizer was used instead of the acrylic polymer solution A so as to have the composition shown in Table 3, and if necessary The dope (DP1-11 and DP1-12) was prepared in the same manner as in Comparative Example 1-1 except that the type and amount of the ultraviolet absorber were changed, and the cellulose acylate film sample (111) was prepared using each of these. And (112) was produced. The film thicknesses of the cellulose acylate film samples (111) and (112) were both in the range of 79.5 to 80.5 μm. In the sample samples (111) and (112), the difference between the maximum value and the minimum value of the 1 m square film cut out arbitrarily was within 5% of the average thickness.

[Evaluation of cellulose acylate film]
[Quantification of residual monomer in film]
Low molecular weight compounds were extracted from the prepared cellulose acylate film samples (101) to (112) using a tetrahydrofuran / methanol mixed solvent, and the amount of residual monomers was quantified by gas chromatography. The results are shown in Table 4.

[Measurement of Retardation Properties (Rth and Re)]
The obtained cellulose acylate films (101) to (112) were measured for retardation properties (Rth and Re) at a wavelength of 630 nm according to the method described in the text. The results are shown in Table 4.

<Preparation of polarizing plate>
Comparative Example 2-1
A polarizer was prepared by adsorbing iodine to a stretched polyvinyl alcohol film.
Next, the saponified cellulose acylate film sample (101) was attached to one side of the polarizer using a polyvinyl alcohol-based adhesive. The slow axis of the transparent support and the transmission axis of the polarizer were arranged in parallel.

  A commercially available cellulose triacetate film “Fujitac TD80UF” (manufactured by Fuji Film Co., Ltd.) was saponified in the same manner as described above, and attached to the opposite side of the polarizer using a polyvinyl alcohol-based adhesive. In this way, a polarizing plate (H-101) was produced.

Examples 2-1 to 2-7 and Comparative Examples 2-2 to 2-5
In producing the polarizing plate (H-101) of Comparative Example 2-1, Comparative Example 2 was used except that the cellulose acylate film samples (102) to (112) were used instead of using the cellulose acylate film sample (101). In the same manner as in Example 1, polarizing plates (H-102) to (H-112) were produced.

[Durability of polarizing plate]
[Evaluation of blank areas on the edges]
Cut out 100 mm × 100 mm samples from each of the polarizing plates (H-101) to (H-112), expose them to an atmosphere of 80 ° C. and 90% RH for 50 hours, and cross the edges of the polarizing plate by crossed Nicols. The area of white spots generated on the surface was observed as an area ratio with respect to the entire area, and the following grade was evaluated.
○: There were no white spots at all.
Δ: White spots are less than 5% of the entire area.
X: The white spot part was 10% or more with respect to the whole area.

[Transmissivity change]
Two samples each having a size of 50 mm × 50 mm were cut out from each of the polarizing plates (H-101) to (H-112), and exposed to an atmosphere of 60 ° C. and 95% RH for 1000 hours to be aged. The transmittance of the polarizing plate in a state of being overlapped with crossed Nicols before and after aging was measured, and the change in transmittance at a wavelength of 410 nm was determined.

  Table 4 shows the data of durability of the obtained polarizing plate (white void at the edge and change in transmittance) together with the type of cellulose acylate film used for each polarizing plate.

  From the results shown in Table 4, the polymer suitably used in the present invention has a high ability to reduce Rth and has an effect of preventing white spots at the edges of the polarizing plate at high temperatures. However, when the polarizing plate was aged for a long time under high humidity conditions, the performance stability was insufficient in the transmittance change. The cellulose acylate film of the present invention in which the residual monomer of the polymer is 1% by mass or less makes it possible to reduce retardation and change the transmittance of the polarizing plate.

[Production of polarizing plate with retardation film]
Example 3
A retardation film obtained by uniaxially stretching a norbornene-based resin film “Arton” {manufactured by JSR Corporation} is attached to the cellulose acylate film (104) side of the polarizing plate (H-104) using an adhesive. A polarizing plate with a retardation film was prepared. At this time, by making the slow axis of the retardation in the front direction of the retardation film orthogonal to the transmission axis of the polarizing plate, the visual characteristics could be improved without changing the front characteristics at all. The retardation film used had a retardation Re in the front direction of 270 nm, a retardation Rth in the thickness direction of 0 nm, and an Nz factor of 0.5.

[Evaluation of mounting on IPS liquid crystal display]
Example 4
Using two sets of polarizing plates with retardation film prepared in Example 3 above, the polarizing film with retardation film, the IPS liquid crystal cell, and the polarizing plate with retardation film so that the retardation films are on the liquid crystal cell side, respectively. In this order, a display device was produced that was stacked and assembled from above. At this time, the transmission axes of the upper and lower polarizing films with the retardation film are orthogonal to each other, and the transmission axes of the upper polarizing films with the retardation film are parallel to the molecular major axis direction of the liquid crystal cell (that is, with the slow axis of the retardation film). The molecular major axis direction of the liquid crystal cell was orthogonal). As the liquid crystal cell, electrode and substrate, those conventionally used as IPS can be used as they are. The alignment of the liquid crystal cell is horizontal alignment, and the liquid crystal has a positive dielectric anisotropy, and those developed and marketed for IPS liquid crystals can be used. The physical properties of the liquid crystal cell were as follows: Δn of liquid crystal: 0.099, cell gap of liquid crystal layer: 3.0 μm, pretilt angle: 5 °, rubbing direction: 75 ° above and below the substrate.

  In the liquid crystal display device produced as described above, the light leakage rate at the time of black display in the azimuth direction 45 ° and polar angle direction 70 ° from the front of the device was measured, and the liquid crystal display device was produced using the cellulose acylate film of the present invention. It has been found that the polarizing plate with a retardation film has a wide contrast viewing angle and is preferable.

Comparative Example 5-1 and Example 5-1
[Preparation of acrylic polymer (P-2)]
Similarly to the acrylic polymer (P-11) in Preparation Example 1, an acrylic polymer (P-2) having a mass average molecular weight of 1700 was obtained by a known synthesis method. Polymers (P-2A) and (P-2B) having different residual monomer contents were obtained by changing the crystallization process.

[Production of Cellulose Acylate Film Samples (501) and (502)]
In the same manner except that the polymer (P-11-1A) in the sample (101) of Comparative Example 1-1 was changed to the polymer (P-2A) or (P-2B), a cellulose acylate film sample ( 501) and (502) were produced. The amount of residual monomer in the cellulose acylate film was 1.2% by mass for the sample (501) and 0.1% by mass for the sample (502) (all values relative to 100 parts by mass of the cellulose acylate film). Here, the amount of residual monomer was calculated as the sum of two types of monomers.

  Using the cellulose acylate film samples (501) and (502), the retardation characteristics (Rth and Re) of the cellulose acylate film were measured in the same manner as in Example 1. The results are shown in Table 5.

Comparative Example 6-1 and Example 6-1
[Production and Evaluation of Polarizing Plate]
Further, polarizing plates (H-501) and (H-502) were produced in the same manner as in Example 2 using cellulose acylate film samples (501) and (502), respectively, and their durability was evaluated. The results are shown in Table 5.

  From Table 5, it can be seen that even the film containing the polymer (P-2) can reduce the optical properties. Moreover, the transmittance | permeability change of a polarizing plate can be made small by reducing the amount of residual monomers.

Example 7-1 and Comparative Example 7-1
The polycondensation polymer PE-1 (number average molecular weight 2000) was synthesized by a known method, and PE-1A and PE-1B in which the content of low molecular components was changed by vacuum distillation were prepared.
In the same manner as in Example 1-1, cellulose acylate film samples (701) and (702) were prepared in the same manner except that PE-1A or PE-1B was replaced with 1-fold mass instead of the polymer P-11-1B. ) Was produced.
Further, in the sample (702), a cellulose acylate film sample (similarly, except that the above-described TN326, which was solid at 25 ° C., was replaced by 1 mass in place of the UV absorbers UV-23L and UV-28L which were liquid at 25 ° C. 703).
Table 6 shows the low molecular ester content and retardation characteristics per film.

Examples 8-1 and 8-2 and Comparative Example 8-1
Also, using these film samples (701), (702) and (703), polarizing plates (H-801), (H-802) and (H-803) were produced in the same manner as described above, and the durability evaluation was performed. went. The results are shown in Table 6.

  Table 6 shows that even a film containing the condensation polymer (PE-1) can reduce the optical properties. Further, by reducing the amount of the low molecular ester, it is possible to reduce white spots and change in transmittance of the polarizing plate. Furthermore, if a liquid ultraviolet absorber at 25 ° C. is used, the change in transmittance can be reduced.

1A and 1B are explanatory views showing two configuration examples in which the polarizing plate of the present invention and a functional optical film are combined. FIG. 2 is an explanatory view showing an example of a liquid crystal display device in which the polarizing plate of the present invention is used.

Explanation of symbols

1, 1a, 1b: protective film 2: polarizer 3: functional optical film 4: adhesive layer 11: upper polarizing plate 12: upper polarizing plate absorption axis 13: upper optical anisotropic layer 14: upper optical anisotropic layer Alignment control direction 15: Liquid crystal cell upper substrate 16: Upper substrate alignment control direction 17: Liquid crystal molecule 18: Liquid crystal cell lower substrate 19: Lower substrate alignment control direction 20: Lower optical anisotropic layer 21: Lower optical anisotropic layer Orientation control direction 22: Lower polarizing plate 23: Lower polarizing plate absorption axis

Claims (11)

  A cellulose acylate film containing a polymer of an ethylenically unsaturated monomer, wherein the ethylenically unsaturated monomer contained in the film is 1% by mass or less per cellulose acylate film. Rate film.   The cellulose acylate film according to claim 1, wherein the polymer is an acrylic polymer.   At least one polycondensate selected from the group consisting of polycondensates obtained by polycondensation of organic acids, glycols and monohydric alcohols, and polycondensates obtained by polycondensation of organic acids and glycols A low molecular weight ester compound obtained by condensing 5 or less molecules, which is a raw material of the polycondensate, contained in the film, is 1 per cellulose acylate film. A cellulose acylate film characterized by being less than or equal to mass%.   The cellulose acylate film according to any one of claims 1 to 3, wherein the cellulose acylate film further contains an ultraviolet absorber, and the ultraviolet absorber is liquid at 25 ° C. The acyl substitution degree of the cellulose acylate in the cellulose acylate film is 2.50 to
It is 3.00 and the average degree of polymerization is 180-700, The cellulose acylate film in any one of Claims 1-4.   The acyl substituent of the cellulose acylate in the cellulose acylate film consists essentially of an acetyl group, the total degree of substitution is 2.50 to 2.95, and the average degree of polymerization is 180 to 550. Item 6. The cellulose acylate film according to any one of Items 1 to 5.   The cellulose acylate film according to claim 1, wherein the thickness of the cellulose acylate film is 10 to 120 μm. The cellulose acylate film according to claim 1, wherein Rth and Re at a wavelength of 630 nm of the cellulose acylate film satisfy the ranges of the following mathematical formulas (1) and (2), respectively.
Formula (1): −25 nm ≦ Rth (630) ≦ 25 nm,
Formula (2): 0 nm ≦ Re (630) ≦ 10 nm   A polarizing plate in which a protective film is bonded to both sides of a polarizer, wherein at least one of the protective films is the cellulose acylate film according to claim 1.   A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein at least one polarizing plate is the polarizing plate according to claim 9.   The liquid crystal display device according to claim 10, wherein the liquid crystal display device is in an IPS mode.

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