JP5720401B2 - Cellulose acetate laminated film, polarizing plate, and liquid crystal display device - Google Patents

Description

  The present invention relates to a cellulose acetate laminated film, a polarizing plate using the same, and a liquid crystal display device. More specifically, the present invention relates to a laminated film, a polarizing plate and a liquid crystal display device in which a cellulose acetate having a low substitution degree and a cellulose acetate having a high substitution degree are co-cast.

  Conventionally, a retardation film having a specific retardation value and a combination thereof have been used in order to improve the viewing angle and color change of a liquid crystal display device.

  As a main raw material for such a retardation film, it is known that cellulose acetate is advantageous, and that the optical properties of the film depend on the degree of acetyl group substitution of cellulose acetate. In particular, cellulose acetate with a low degree of substitution has a high intrinsic birefringence. Therefore, by reducing the degree of acyl group substitution, a phase difference for a vertical alignment type (also referred to as “VA (Vertical Alignment) type”) liquid crystal display device. It is considered possible to realize high optical expression suitable as a film.

  Moreover, as described in Patent Documents 1 to 4, the surface can be directly bonded to a polarizer mainly composed of polyvinyl alcohol by being saponified by immersing it in an alkaline aqueous solution and hydrophilizing. For this reason, it is utilized as a protective film (hereinafter, also simply referred to as “protective film”) to which a phase difference compensation function of a polarizer is added.

  The polarizer bonded with the protective film is incorporated together with the liquid crystal cell when the liquid crystal display device is manufactured. At this time, since the protective film is disposed between the polarizer and the liquid crystal cell, the optical characteristics of the protective film greatly affect the visibility of the liquid crystal display device. For this reason, the protective film is required to exhibit stable optical characteristics against environmental changes such as humidity changes.

  However, the cellulose acetate film has a problem that its dimensions are likely to fluctuate particularly with respect to humidity changes. In recent years, with the wide viewing angle and high image quality of liquid crystal display devices, it has been required to further improve the compensation of phase difference, and improvement has been demanded.

  In order to improve the stability against humidity change, a film made of a more hydrophobic polycarbonate or cyclooff olefin polymer has been proposed (see, for example, Patent Document 5). Such films are also commercially available.

  However, these films are improved in change with respect to humidity, but have a problem that it is difficult to adhere to a polarizer mainly composed of polyvinyl alcohol. For this reason, the further improvement was calculated | required.

  Thus, in the film directly bonded to the polarizer, the bonding property with the polarizer and the dimensional stability against humidity change have a trade-off relationship.

  In order to improve this relationship, it has been proposed to use a cellulose acetate film having a low water contact angle (for example, Patent Document 6).

  Further, it has been proposed to use a cellulose acetate having a low acyl group substitution degree for the skin layer (surface layer) in a laminated structure (see, for example, Patent Documents 7 and 8).

  However, the cellulose acetate film with a low contact angle is saponified by immersing the surface in an alkaline aqueous solution, and film surface elution is likely to occur in the process of making it hydrophilic, and it is necessary to weaken the immersing treatment. Adhesion was not obtained, and the relationship was in conflict with dimensional stability against humidity changes. In addition, there is a problem in that the peelability from the metal belt at the time of casting is poor, the metal belt is contaminated, and an external force acts on the film, so that a horizontal stage of the film is likely to occur and a phase difference different from that desired is likely to occur. .

  Furthermore, when cellulose acetate having a low acyl group substitution degree in the range of 1.8 to 2.2 without using a saponification step is used, the viscosity when dissolved in a halogenated solvent such as dichloromethane is high, and the solution casting is performed. There arises a problem that the surface condition after film formation deteriorates.

JP 7-151914 A JP-A-8-94838 JP 2001-166146 A JP 2001-188130 A JP 2001-318233 A JP 2006-215535 A Japanese Patent No. 4279178 Japanese Patent Application No. 2010-191905

  The present invention has been made in view of the above-mentioned problems and situations, and its solution is a cellulose acetate laminated film that has excellent bonding properties with a polarizer, excellent contrast performance, and small dimensional change due to humidity. Is to provide. Another object of the present invention is to provide a highly reliable polarizing plate and a liquid crystal display device provided with the cellulose acetate multilayer film.

  The above-mentioned problem according to the present invention is solved by the following means.

1. A skin B layer containing cellulose acetate satisfying the following formula (1), a core layer containing cellulose acetate satisfying the following formula (2), and a skin A layer containing cellulose acetate satisfying the following formula (2) A cellulose acetate laminated film formed by lamination, wherein the core layer contains a compound having negative intrinsic birefringence.
Formula (1): 2.7 <Z ₁ <3.0
(In the formula (1), Z ₁ represents the total degree of acetyl group substitution of the cellulose acetate of the skin layer B.)
Formula (2): 2.0 <Z ₂ <2.7
(In the formula (2), Z ₂ represents the total degree of acetyl group substitution of the cellulose acetate of the core layer and skin layer A.)
2. (A) a dicarboxylic acid residue having an average carbon number of 5.5 to 10.0 including an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue; and (b) an average carbon number of 2. The cellulose acetate laminated film according to the above item 1, which contains a polycondensed ester containing an aliphatic diol residue in the range of 5 to 7.0.

  3. 3. The cellulose acetate laminated film according to item 1 or 2, wherein at least one of the skin A layer and the skin B layer contains a polymer having a cyclic structure in a side chain.

  4). The cellulose acetate laminated film according to any one of items 1 to 3, wherein metal fine particles and an amine-based dispersant are contained in at least one of the skin A layer and the skin B layer. .

  5. The average layer thickness of the core layer is in the range of 30 to 100 μm, and the average layer thickness of at least one of the skin A layer and the skin B layer is in the range of 0.2 to 25% of the average layer thickness of the core layer. The cellulose acetate laminated film according to any one of Items 1 to 4, wherein the film is a cellulose acetate laminated film.

  6). The film width is in the range of 700 to 3000 mm, the cellulose acetate laminated film according to any one of the first to fifth items.

  7). The core layer contains a compound represented by the following general formula (A) having a total average degree of substitution within the range of 4.5 to 6.9. The cellulose acetate laminated film according to any one of the above.

(Wherein R _{1 to} R ₈ each independently represents a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ may be the same) , May be different.)
8). Nz coefficient represented by following formula (3) is 7 or less, The cellulose acetate laminated film as described in any one of said 1st term | claim to 7th term | claim characterized by the above-mentioned.
Formula (3): Nz coefficient = Rth / Re + 0.5
9. A polarizing plate comprising the cellulose acetate laminated film according to any one of items 1 to 8 above.

  10. A liquid crystal display device comprising the cellulose acetate laminated film according to any one of items 1 to 8 above.

  By the said means of this invention, the cellulose-acetate laminated | multilayer film which is excellent in pasting property with a polarizer, is excellent in contrast performance, and has a small dimensional change by humidity can be provided. In addition, a highly reliable polarizing plate and a liquid crystal display device provided with the cellulose acetate multilayer film can be provided.

  According to the present invention, a cellulose acetate laminate in which the adhesiveness to a hydrophilic film and a desired retardation development property that cannot be realized by a conventional cellulose acetate film are compatible and the fluctuation range due to humidity change is minimized. A film can be provided.

  That is, it is possible to eliminate the need for the conventional treatment of improving the adhesion while maintaining the releasability from the metal belt so as to obtain an adhesiveness with the hydrophilic film by alkali treatment of the surface.

  Furthermore, according to the preferable aspect of this invention, when it has a skin layer on both surfaces of a core layer, the physical property (curl) of a film can also be controlled suitably. Such a film and a polarizing plate using the film can be preferably used for a liquid crystal display device, and can be particularly preferably used for a VA liquid crystal display device.

Co-casting die and a diagram showing a multi-layered web formed by casting Conceptual diagram showing the internal haze measurement method

  In the cellulose acetate laminated film of the present invention, a skin B layer containing cellulose acetate satisfying the formula (1), a core layer containing cellulose acetate satisfying the formula (2), and a skin A layer are laminated. The cellulose acetate laminated film is characterized in that the core layer contains a compound having negative intrinsic birefringence. This feature is a technical feature common to the inventions according to claims 1 to 10.

  As an embodiment of the present invention, from the viewpoint of manifesting the effect of the present invention, (a) an average carbon number in the range of 5.5 to 10.0 including an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue. It is preferable to contain a polycondensation ester containing an inner dicarboxylic acid residue and (b) an aliphatic diol residue having an average carbon number in the range of 2.5 to 7.0. Furthermore, it is preferable that at least one of the skin A layer and the skin B layer contains a polymer having a cyclic structure in the side chain.

  In the present invention, it is preferable that at least one of the skin A layer and the skin B layer contains metal fine particles and an amine-based dispersant. Moreover, the average layer thickness of the said core layer exists in the range of 30-100 micrometers, The average layer thickness of at least one of the said skin A layer and the skin B layer is 0.2-25% of the average layer thickness of the said core layer. It is preferable to be within the range. Furthermore, the film width is preferably in the range of 700 to 3000 mm.

  In the present invention, the core layer contains a compound represented by the general formula (A) having a total average substitution degree in the range of 4.5 to 6.9. The cellulose acetate laminated film according to any one of claims 6 to 7. Moreover, it is preferable that the Nz coefficient represented by the said Formula (3) is 7 or less.

  The cellulose acetate laminated film of the present invention can be suitably used for polarizing plates and liquid crystal display devices.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

  The following terms and symbols used in the present application are defined as follows.

(1) “n _x ” is the refractive index in the direction in which the in-plane refractive index is maximized (ie, the slow axis direction), and “n _y ” is the direction in the plane perpendicular to the slow axis (ie, the slow axis direction). , The fast axis direction), and “ _nz ” is the refractive index in the thickness direction.

Further, for example, _"n x = _{n y"} is, _{n x} and _{n y} are not only exactly equal, but also a case where _{n x} and _{n y} are substantially equal. By "substantially equal" in the present application, n _x and n _y in a range which does not give practical effect on the overall optical properties of the liquid crystal panel is a spirit encompasses vary.

(2) “In-plane retardation (retardation) Re” refers to a retardation value in a film (layer) plane measured with light having a wavelength of 590 nm at 23 ° C. and 55% RH. Re is, when the respective slow axis direction of the film (layer) at a wavelength of 590 nm, the refractive index of the fast axis _direction, and n x, _{n y,} and a thickness of d (nm) of the film (layer), the formula: Re ₌ determined by _{(n x -n y) × d} .

(3) “Thickness direction retardation (phase difference) Rth” refers to a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C. and 55% RH. Rth is the slow axis direction of the film (layer) at a wavelength of 590 nm, a fast axis direction, refractive index in the thickness direction, _{respectively,} and _{n x, n y, n z} , d of (nm) of the film (layer) When the thickness is taken, it is obtained by the formula: Rth = {(n _x + n _y ) / 2−n _z )} × d.

  (4) “Nz coefficient” is a value calculated by the formula: Rth / Re + 0.5.

  In the present application, the “core layer” refers to a layer on the inner side of the laminated layers when the cellulose acetate laminated film is composed of three or more laminated layers. The layer thickness is preferably thicker than the skin layer on the outside. In addition, when the cellulose acetate laminated film has a two-layer structure, a layer having the thickest layer is defined as a “core layer”.

  On the other hand, the “skin layer” refers to a layer on the outer surface side of the laminated layers when the cellulose acetate laminated film is composed of three or more laminated layers. The layer thickness is preferably thinner than the core layer on the inner side.

  In the present application, the term “skin layer” refers to both “skin A layer” and “skin B layer”.

  The “skin A layer” may be referred to as an “air surface layer”, and the “skin B layer” may be referred to as a “support surface layer”. Furthermore, the “core layer” may be referred to as a “base layer”.

[Cellulose acetate laminate film]
The cellulose acetate laminated film of the present invention (hereinafter also referred to as “the film of the present invention”) is composed of a skin B layer containing a cellulose acetate satisfying the following formula (1) and a cellulose acetate satisfying the following formula (2). A cellulose acetate laminated film in which a core layer to be contained is laminated and formed, wherein at least one of the skin A layer and the core layer contains a compound having negative intrinsic birefringence.

Formula (1): 2.7 <Z ₁ <3.0
(In the formula (1), Z ₁ represents the total degree of acetyl group substitution of the cellulose acetate of the skin layer.)
Formula (2): 2.0 <Z ₂ <2.7
(In the formula (2), Z ₂ represents the total degree of acetyl group substitution of the cellulose acetate of the core layer.)
As a preferred embodiment of the present invention, the core layer preferably contains a compound having negative intrinsic birefringence. Thereby, the color balance of a liquid crystal display device can be made favorable. Furthermore, the core layer preferably contains a polycondensed ester.

  In the present invention, the skin A layer preferably contains a compound having negative intrinsic birefringence. Moreover, it is the aspect which has the skin B layer containing the cellulose acetate which satisfy | fills following formula (1) on the surface on the opposite side to the surface with the skin A layer of the said laminated | stacked core layer, The said skin B It is preferable that the layer contains fine metal particles and an amine-based dispersant to improve the peelability of the film from the metal belt, to suppress the expression and variation of Re and Rth, and to obtain a desired value. Further, the skin A layer preferably contains a polymer having a cyclic structure in the side chain.

  It is a preferable aspect of the present invention to use a low-substitution degree cellulose acetate satisfying the formula (2) and a polymer having a cyclic structure in the side chain as the skin A layer to form a laminated film. As a result, the adhesion of the cellulose acetate laminated film to the hydrophilic film is enhanced.

  Furthermore, it is also a preferred embodiment that a polycondensation ester is added to at least one of the core layer or the skin A layer and stretched, and partial fluctuations in the thickness of the core layer and the skin A layer that are technically unavoidable in co-casting occur. Even if it is a case, it can suppress the influence which the optical characteristic of the whole laminated film receives, and can suppress the variation of Re and Rth.

  Therefore, compared with the conventional cellulose acetate film, the cellulose acetate laminated film of the present invention has high expression of optical characteristics and very little variation in optical characteristics.

  In the present invention, from the viewpoint of film strength and productivity, the average layer thickness of the core layer is in the range of 30 to 100 μm, and the average layer thickness of at least one of the skin A layer and the skin B layer is the core layer. The average layer thickness is preferably in the range of 0.2 to 25%. Furthermore, from the viewpoint of optical uniformity, the film width is preferably in the range of 700 to 3000 mm.

(Cellulosic resin)
The cellulose acetate laminated film of the present invention is a cellulose acetate laminated film in which a skin B layer containing a specific cellulose acetate, a core layer containing a specific cellulose acetate, and a skin A layer are laminated and formed. Features.

  The cellulose resin used in the present invention is not particularly defined as long as the total substitution degree of the acyl group satisfies the formulas (1) and (2).

  In the present invention, it is necessary to use at least cellulose acetate as the cellulose resin.

  Examples of cellulose as an acetate raw material include cotton linter and wood pulp (hardwood pulp, softwood pulp). Cellulose acetate obtained from any raw material cellulose can be used, and in some cases, it may be mixed and used. Detailed descriptions of these raw material celluloses can be found in, for example, Marusawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, Nikkan Kogyo Shimbun (published in 1970) and Invention Association Publication Technical Report No. 2001-1745. No. (pages 7 to 8) can be used.

(Cellulose acetate)
Glucose units having β-1,4 bonds constituting cellulose have free hydroxy groups (hydroxyl groups) at the 2nd, 3rd and 6th positions. Cellulose acetate is a polymer obtained by acetylating part or all of these hydroxy groups (hydroxyl groups) with acetyl groups. The degree of acetyl group substitution means the ratio of cellulose acetylation (hydroxyl group) located at the 2-position, 3-position and 6-position (100% acetylation is substitution degree 1).

  Z1 more preferably satisfies 2.75 <Z1 <2.95, and particularly preferably satisfies 2.80 <Z1 <2.95.

  Z2 more preferably satisfies 2.1 <Z2 <2.6, and particularly preferably satisfies 2.3 <Z2 <2.5.

  The film of the present invention has a skin A layer containing cellulose acetate satisfying the formula (2) on the surface of the core layer opposite to the skin B layer. Is more preferable from the viewpoint of suitably controlling.

  In the acetylation of cellulose in the present invention, when an acid anhydride or acid chloride is used as an acetylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent. .

As the catalyst, when the acetylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acetylating agent is an acid chloride (for example, CH ₃ COCl), a basic catalyst is used. A compound is used.

  The most common industrial synthesis method of cellulose fatty acid esters is cellulose, mixed organic acids containing fatty acids (acetic acid, propionic acid, valeric acid, etc.) corresponding to acetyl groups and other acyl groups, or acid anhydrides thereof. This is a method of acylating with components.

  The cellulose acetate used for this invention is compoundable by the method described in Unexamined-Japanese-Patent No. 10-45804, for example.

<Polycondensed ester>
The cellulose acetate laminated film of the present invention comprises (a) an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue, and an average carbon number in the range of 5.5 to 10.0, (B) It is preferable that it is a laminated | multilayer film film of the aspect containing the polycondensation ester containing the aliphatic diol residue in the range whose average carbon number is 2.5-7.0.

  The polycondensed ester according to the present invention is a mixture of at least one dicarboxylic acid having an aromatic ring (also referred to as “aromatic dicarboxylic acid”) and at least one aliphatic dicarboxylic acid, for example, having an average carbon number of 5. It is obtained from 5 to 10.0 dicarboxylic acid and at least one aliphatic diol having an average carbon number of 2.5 to 7.0.

  Calculation of the average carbon number of the aliphatic dicarboxylic acid residue is performed separately for the dicarboxylic acid residue and the diol residue.

  The value calculated by multiplying the composition ratio (molar fraction) of the dicarboxylic acid residue by the constituent carbon number is defined as the average carbon number. For example, when the adipic acid residue and the phthalic acid residue are composed of 50 mol% each, the average carbon number is 7.0.

  The same applies to a diol residue. The average carbon number of an aliphatic diol residue is a value calculated by multiplying the constituent carbon number by the composition ratio (molar fraction) of the aliphatic diol residue. For example, when it is composed of 50 mol% of ethylene glycol residues and 50 mol% of 1,2-propanediol residues, the average carbon number is 2.5.

  The number average molecular weight of the polycondensed ester is preferably 500 to 2000, more preferably 600 to 1500, and still more preferably 700 to 1200. If the number average molecular weight of the polycondensed ester is 600 or more, the volatility is low, and film failure or process contamination due to volatilization under high temperature conditions during stretching of the cellulose ester film is less likely to occur. Moreover, if it is 2000 or less, compatibility with a cellulose ester will become high, and it will become difficult to produce the bleed-out at the time of film forming and the heat-stretching.

  The number average molecular weight of the polycondensed ester according to the present invention can be measured and evaluated by gel permeation chromatography. Further, in the case of a polyester polyol having an unsealed terminal, it can also be calculated from the amount of hydroxy group (hydroxyl group) per mass (hereinafter, hydroxy value (hydroxyl value)). The hydroxy value (hydroxyl value) is determined by measuring the amount (mg) of potassium hydroxide necessary for neutralizing excess acetic acid after acetylating the polyester polyol.

  The dicarboxylic acid as a mixture of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid according to the present invention is a dicarboxylic acid having an average carbon number of 5.5 or more and 10.0 or less. More preferably, it is 5.6 or more and 8 or less.

  If the average carbon number is 5.5 or more, a polarizing plate having excellent durability can be obtained. If the average number of carbon atoms is 10 or less, the compatibility with the cellulose ester is excellent, and the occurrence of bleed out can be suppressed in the process of forming the cellulose ester film.

  The polycondensed ester according to the present invention can be used as a plasticizer.

(Aromatic dicarboxylic acid residue)
The aromatic dicarboxylic acid residue is contained in a polycondensed ester obtained from a diol and a dicarboxylic acid containing an aromatic dicarboxylic acid.

  In the present specification, the “residue” is a partial structure of a polycondensed ester and represents a partial structure having characteristics of a monomer forming the polycondensed ester. For example, the dicarboxylic acid residue formed from the dicarboxylic acid HOOC-R—COOH is —OC—R—CO—.

  The aromatic dicarboxylic acid residue ratio of the polycondensed ester used in the present invention is 40 mol% or more, preferably 40 mol% to 95 mol%. More preferably, it is 45 mol%-70 mol%, and still more preferably 50 mol%-70 mol%.

  By setting the aromatic dicarboxylic acid residue ratio to 40 mol% or more, a cellulose ester film exhibiting sufficient optical anisotropy can be obtained, and a polarizing plate excellent in durability can be obtained. Moreover, if it is 95 mol% or less, it is excellent in compatibility with a cellulose ester, and it can make it hard to produce a bleed-out also at the time of film forming of a cellulose ester film, and the time of heat-stretching.

  Examples of the aromatic dicarboxylic acid used in the present invention include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, and 2,8-naphthalene. Examples thereof include dicarboxylic acid and 2,6-naphthalenedicarboxylic acid. Phthalic acid, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred, phthalic acid and terephthalic acid are more preferred, and terephthalic acid is even more preferred.

  In the polycondensed ester, an aromatic dicarboxylic acid residue is formed by the aromatic dicarboxylic acid used for mixing.

  Specifically, the aromatic dicarboxylic acid residue preferably includes at least one of a phthalic acid residue, a terephthalic acid residue, and an isophthalic acid residue, more preferably at least one of a phthalic acid residue and a terephthalic acid residue. 1 type is included, More preferably, a terephthalic acid residue is included.

  That is, by using terephthalic acid as the aromatic dicarboxylic acid for mixing in the formation of the polycondensed ester, it is more compatible with the cellulose ester and causes bleed-out even when the cellulose ester film is formed and heated and stretched. It can be set as a difficult cellulose-ester film. Moreover, aromatic dicarboxylic acid may be used alone or in combination of two or more. When two types are used, it is preferable to use phthalic acid and terephthalic acid.

  By using together two kinds of aromatic dicarboxylic acids of phthalic acid and terephthalic acid, the polycondensation ester at normal temperature can be softened, which is preferable in terms of easy handling.

  The content of the terephthalic acid residue in the dicarboxylic acid residue of the polycondensed ester is preferably 40 mol% to 95 mol%, preferably 45 mol% to 70 mol%, and preferably 50 mol% to 70 mol%. .

  By setting the terephthalic acid residue ratio to 40 mol% or more, a cellulose ester film exhibiting sufficient optical anisotropy can be obtained. Moreover, if it is 95 mol% or less, it is excellent in compatibility with a cellulose ester, and it can make it hard to produce a bleed-out also at the time of film forming of a cellulose ester film, and the time of heat-stretching.

(Aliphatic dicarboxylic acid residue)
The aliphatic dicarboxylic acid residue is contained in a polycondensed ester obtained from a diol and a dicarboxylic acid containing an aliphatic dicarboxylic acid.

  In the present specification, a residue is a partial structure of a polycondensed ester and represents a partial structure having the characteristics of a monomer forming the polycondensed ester. For example, the dicarboxylic acid residue formed from dicarboxylic acid HOOC-R-COOH is -OC-R-CO-.

  Examples of the aliphatic dicarboxylic acid preferably used in the present invention include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. Examples include acid or 1,4-cyclohexanedicarboxylic acid.

  In the polycondensed ester, an aliphatic dicarboxylic acid residue is formed from the aliphatic dicarboxylic acid used for mixing.

  The dicarboxylic acid residue preferably has an average carbon number in the range of 5.5 to 10.0, more preferably 5.5 to 8.0, and 5.5 to 7.0. Is more preferable. If the average carbon number of the aliphatic diol is 7.0 or less, the heat loss of the compound can be reduced, and the occurrence of planar failure that may be caused by process contamination due to bleed-out during drying of the cellulose acetate web can be prevented. . Moreover, it is preferable that the aliphatic diol has an average carbon number of 2.5 or more because the compatibility is excellent and precipitation of the polycondensed ester hardly occurs.

  Specifically, it preferably contains a succinic acid residue, and when two types are used, it preferably contains a succinic acid residue and an adipic acid residue. That is, one or two or more aliphatic dicarboxylic acids may be used for mixing in the formation of the polycondensed ester. When two types are used, it is preferable to use succinic acid and adipic acid. When one kind is used, it is preferable to use succinic acid. The average carbon number of the diol residue can be adjusted to a desired value, which is preferable in terms of compatibility with the cellulose ester.

  In the present invention, two or three dicarboxylic acids are preferably used. When using two kinds, it is necessary to use one kind of aliphatic dicarboxylic acid and one kind of aromatic dicarboxylic acid. When using three kinds, one kind of aliphatic dicarboxylic acid and two kinds of aromatic dicarboxylic acid or aliphatic dicarboxylic acid are used. Two kinds of acids and one kind of aromatic dicarboxylic acid can be used. This is because the average carbon number value of the dicarboxylic acid residue can be easily adjusted, the content of the aromatic dicarboxylic acid residue can be within a preferable range, and the durability of the polarizer can be improved.

(Aliphatic diol)
The aliphatic diol residue is contained in a polycondensed ester obtained from an aliphatic diol and a dicarboxylic acid containing a dicarboxylic acid.

  In the present specification, a residue is a partial structure of a polycondensed ester and represents a partial structure having the characteristics of a monomer forming the polycondensed ester. For example, the diol residue formed from the diol HO—R—OH is —O—R—O—.

  Examples of the diol that forms the polycondensed ester include aromatic diols and aliphatic diols, including at least aliphatic diols.

  The polycondensed ester contains an aliphatic diol residue having an average carbon number of 2.5 to 7.0. Preferably, it is an aliphatic diol residue having an average carbon number of 2.5 to 4.0. When the average carbon number of the aliphatic diol residue is larger than 3.0, the compatibility with the cellulose ester is low, the bleedout is likely to occur, the weight loss of the compound is increased, and the cellulose acetate web is dried. Planar failures occur that may be caused by contamination. In addition, if the aliphatic diol residue has an average carbon number of less than 2.0, the synthesis becomes difficult, so it cannot be used.

  Examples of the aliphatic diol used in the present invention include alkyl diols and alicyclic diols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3- Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl -1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, diethylene glycol, cyclohexanedimethanol, etc. Is preferably used together with ethylene glycol as one or a mixture of two or more.

  The preferred aliphatic diol is at least one of ethylene glycol, 1,2-propanediol, and 1,3-propanediol, and particularly preferably at least one of ethylene glycol and 1,2-propanediol. When two types are used, it is preferable to use ethylene glycol and 1,2-propanediol. By using 1,2-propanediol or 1,3-propanediol, crystallization of the polycondensed ester can be prevented.

  In the polycondensed ester, a diol residue is formed by the diol used for mixing.

  The diol residue preferably contains at least one of an ethylene glycol residue, a 1,2-propanediol residue, and a 1,3-propanediol residue, and is an ethylene glycol residue or a 1,2-propanediol residue. More preferably.

  Among the aliphatic diol residues, the ethylene glycol residue is preferably 20 mol% to 100 mol%, and more preferably 50 to 100 mol%.

(Sealing)
The terminal of the polycondensed ester according to the present invention is not capped and remains a diol or carboxylic acid, or may be further reacted with a monocarboxylic acid or monoalcohol to carry out so-called terminal capping.

  As monocarboxylic acids used for sealing, acetic acid, propionic acid, butanoic acid and the like are preferable, acetic acid or propionic acid is more preferable, and acetic acid is most preferable. As monoalcohols used for sealing, methanol, ethanol, propanol, isopropanol, butanol, isobutanol and the like are preferable, and methanol is most preferable. When the number of carbon atoms of the monocarboxylic acid used at the terminal of the polycondensed ester is 3 or less, the loss on heating of the compound does not increase, and no surface failure occurs.

  More preferably, the terminal of the polycondensed ester of the present invention is not sealed and remains a diol residue, or is more preferably sealed with acetic acid or propionic acid.

  Both ends of the polycondensed ester according to the present invention may be sealed or unsealed.

  When both ends of the condensate are unsealed, the polycondensed ester is preferably a polyester polyol.

  One aspect of the polycondensation ester according to the present invention is a polycondensation ester in which the aliphatic diol residue has a carbon number of 2.5 or more and 7.0 or less, and both ends of the condensate are unsealed. Can do.

  When both ends of the condensate are sealed, it is preferably sealed by reacting with a monocarboxylic acid. At this time, both ends of the polycondensed ester are monocarboxylic acid residues. In the present specification, a residue is a partial structure of a polycondensed ester and represents a partial structure having the characteristics of a monomer forming the polycondensed ester. For example, the monocarboxylic acid residue formed from monocarboxylic acid R—COOH is R—CO—. It is preferably an aliphatic monocarboxylic acid residue, more preferably an aliphatic monocarboxylic acid residue having 22 or less carbon atoms, and an aliphatic monocarboxylic acid residue having 3 or less carbon atoms. More preferably it is. In addition, an aliphatic monocarboxylic acid residue having 2 or more carbon atoms is preferable, and an aliphatic monocarboxylic acid residue having 2 carbon atoms is particularly preferable.

  One aspect of the polycondensation ester according to the present invention is a polycondensation ester in which the aliphatic diol residue has a carbon number of more than 2.5 and 7.0 or less, and both ends of the condensate are monocarboxylic acid residues. Can be mentioned.

  When the number of carbon atoms of the monocarboxylic acid residue at both ends of the polycondensed ester is 3 or less, the volatility is lowered, the weight loss due to heating of the polycondensed ester does not increase, and process contamination and surface failure occur. Can be reduced.

  That is, aliphatic monocarboxylic acids are preferable as monocarboxylic acids used for sealing. More preferably, the monocarboxylic acid is an aliphatic monocarboxylic acid having 2 to 22 carbon atoms, more preferably an aliphatic monocarboxylic acid having 2 to 3 carbon atoms, and an aliphatic monocarboxylic acid having 2 carbon atoms. A residue is particularly preferred.

  For example, acetic acid, propionic acid, butanoic acid, benzoic acid and derivatives thereof are preferable, acetic acid or propionic acid is more preferable, and acetic acid is most preferable.

  Two or more monocarboxylic acids used for sealing may be mixed.

  Both ends of the polycondensed ester of the present invention are preferably sealed with acetic acid or propionic acid, and most preferably both ends become acetyl ester residues (sometimes referred to as acetyl residues) by acetic acid sealing.

  When both ends are sealed, the state at normal temperature is unlikely to be in a solid form, the handling is good, and a cellulose ester film excellent in humidity stability and polarizing plate durability can be obtained.

  Specific examples A-1 to A-31, B-3, B-4, B-6, B-9, B-10 of the polycondensation ester according to the present invention in the following Tables 1 to 3 and the scope according to the present invention Specific examples B-1, B-2, B-5, B-7, and B-8 of other polycondensation esters will be described, but are not limited thereto.

  The synthesis of the polycondensed ester according to the present invention may be carried out by any of conventional methods such as a hot melt condensation method by a polyesterification reaction or transesterification reaction between a diol and a dicarboxylic acid, or an interfacial condensation method between these acid chlorides and glycols. This method can be easily synthesized. In addition, the polycondensed ester according to the present invention is described in detail in Koichi Murai, “Plasticizer Theory and Application” (Kokai Shobo Co., Ltd., first edition issued on March 1, 1973). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.

  The content of the polycondensed ester in the cellulose ester film is preferably 1 to 20% by mass, more preferably 2 to 10% by mass, and 2 to 5% by mass with respect to the amount of cellulose ester. Most preferred.

  The content of the raw material aliphatic diol, dicarboxylic acid ester, or diol ester contained in the polycondensate according to the present invention in the cellulose ester film is preferably less than 1% by mass, and more preferably less than 0.5% by mass. Examples of the dicarboxylic acid ester include dimethyl phthalate, di (hydroxyethyl) phthalate, dimethyl terephthalate, di (hydroxyethyl) terephthalate, di (hydroxyethyl) adipate, and di (hydroxyethyl) succinate. Examples of the diol ester include ethylene diacetate and propylene diacetate.

<Compound represented by formula (A)>
In the film of the present invention, a compound represented by the following general formula (A), a compound having negative intrinsic birefringence] a plasticizer such as a phthalate ester or a phosphate ester; an ultraviolet absorber; an antioxidant; a mat Additives such as agents can also be added.

  In the present invention, the core layer preferably contains a compound represented by the following general formula (A) having a total average substitution degree in the range of 4.5 to 6.9.

(Wherein R _{1 to} R ₈ each independently represents a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ may be the same) , May be different.)
Preferable specific examples of the compound represented by the general formula (A) include compounds shown in Tables 1 to 3. In addition, R described in Table 4 below represents any one of R _{1 to} R ₈ . As the substituent for the alkylcarbonyl group and the arylcarbonyl group, substituents such as a phenyl group and an alkoxy group included in the alkylcarbonyl group and the arylcarbonyl group shown in the following table are preferable.

<Compound with negative intrinsic birefringence>
In the present application, the “compound having negative intrinsic birefringence” refers to a compound exhibiting negative intrinsic birefringence in a specific direction of the film in the cellulose acetate film. “Negative intrinsic birefringence” refers to the property of negative birefringence. Whether or not it has a negative intrinsic birefringence can be known, for example, by measuring the birefringence of the film in a system not added with the compound with a birefringence meter and comparing the difference. it can.

  The compound having negative intrinsic birefringence according to the present invention is not particularly limited, and known compounds exhibiting negative intrinsic birefringence can be used.

  Examples of the compound having negative intrinsic birefringence include a polymer having negative intrinsic birefringence, and acicular fine particles having negative intrinsic birefringence (including polymer acicular fine particles having negative intrinsic birefringence). Can be mentioned. Hereinafter, a polymer having negative intrinsic birefringence that can be used in the present invention will be described.

<Polymer having negative intrinsic birefringence>
“Polymer having negative intrinsic birefringence” refers to a direction in which the refractive index of light in the alignment direction is orthogonal to the alignment direction when light is incident on a layer formed with molecules having a uniaxial alignment. The polymer (polymer) which becomes smaller than the refractive index of light.

  Examples of such a polymer having a negative intrinsic birefringence include a polymer having a specific cyclic structure, a styrene polymer such as polystyrene and a styrene-maleic anhydride copolymer (SMA resin), and an acrylic such as polymethyl methacrylate. Polymers, cellulose ester polymers (except those with positive birefringence), polyester polymers (except those with positive birefringence), polymers with furanose or pyranose structures, acrylonitrile polymers, alkoxysilyls Examples thereof include polymers and multi-component (binary, ternary, etc.) copolymer polymers thereof. These may be used individually by 1 type and may use 2 or more types together. Further, when it is a copolymer, it may be a block copolymer or a random copolymer.

  Among these, a polymer having a specific cyclic structure, a styrene polymer, and an acrylic polymer are more preferable, and polyvinylpyrrolidone, polystyrene, poly α-methylstyrene, polyhydroxystyrene, polyacrylate, polyacrylic ester, and styrene-maleic acid. A copolymer is particularly preferred.

(Polymer having specific cyclic structure in side chain)
The cellulose acetate laminated film of the present invention preferably contains a polymer having a cyclic structure in the side chain in at least one of the skin A layer and the skin B layer.

  As the polymer having negative intrinsic birefringence, a polymer having a cyclic structure represented by the general formula (21) or (22) in the side chain is also preferable.

  It may have only one or a plurality of cyclic structures represented by the general formula (21) or (22), and may have a side chain in addition to that.

(Circular structure represented by general formula (21))
The cyclic structure represented by the general formula (21) will be described.

In the general formula (21), X ¹ represents CR ¹ or a nitrogen atom, and is preferably a nitrogen atom. In addition, * represents a connection part with a polymer. The same applies to the following general formulas (22) to (25).

R ¹ represents a hydrogen atom or a monovalent substituent, and the monovalent substituent is not particularly limited. Examples of the monovalent substituent include the substituents described immediately after the specific examples c1 to c15 of the linking group (c) in the description of the retardation developer described below.

Y ¹ represents a carbon atom, a nitrogen atom or a sulfur atom, preferably a carbon atom or a sulfur atom, and more preferably a carbon atom.

L ¹ represents a single bond or a connecting group having a connecting chain length of 1 atom, and L ¹ is preferably a single bond. The atom linking group is not particularly limited, and examples thereof include a divalent carbon atom-containing linking group, a divalent nitrogen atom-containing linking group, a sulfur atom, and an oxygen atom.

L ² represents a linking group having a linking chain length of 2 to 6 atoms. The connecting chain length of L ² is preferably 2 to 5 atoms, and more preferably 2 to 4 atoms. The linking group is not particularly limited as long as it is divalent, and examples thereof include a divalent carbon atom-containing linking group and a divalent nitrogen atom-containing linking group. The linking group may further have a substituent. Examples of such a substituent include the substituents described immediately after the specific examples c1 to c15 of the linking group (c) in the description of the retardation developer described later.

L ² is particularly preferably a substituted or unsubstituted alkylene group having 2 to 4 carbon atoms.

  The cyclic structure represented by the general formula (21) may form an aromatic ring, a hetero ring, or an aromatic hetero ring as a whole. Moreover, although the some cyclic structure may be included, it is preferable that it is a single cyclic structure.

As a preferable combination of X ¹ , Y ¹ , L ¹ and L ² , X ¹ is a nitrogen atom, Y ¹ is a carbon atom, L ¹ is a single bond, and L ² has ² to 4 carbon atoms. The case where it is a substituted or unsubstituted alkylene group is preferable, and it is more preferable that it is a structure represented by General formula (23) or (24).

(Circular structure represented by general formula (23) or (24))
First, the cyclic structure represented by the general formula (23) will be described.

In General Formula (23), R ¹⁹ represents a substituted or unsubstituted alkylene group having 2 to 4 carbon atoms, and a substituted or unsubstituted alkylene group having 3 carbon atoms is more preferable.

  Examples of the substituent include the substituents described immediately after the specific examples c1 to c15 of the linking group (c) in the description of the retardation developer described below. In addition, the substituent may or may not have a structure of —C (═O) —, but if it has, —C (═O) — in the general formula (23). It is preferable that the direction is close to the parallel direction.

(Circular structure represented by general formula (24))
Next, the cyclic structure represented by the general formula (24) will be described.

In the general formula (24), R ²⁰ represents a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms. R ²⁰ is more preferably a substituted or unsubstituted alkylene group having 2 carbon atoms.

  As said substituent, the thing similar to what was demonstrated by General formula (23) can be used, and its preferable range is also the same.

  The cyclic structure represented by the general formula (21) is most preferably a pyrrolidone structure.

  Although the specific example of the cyclic structure represented by the said General formula (21), (23) or (24) is given, it is not limited to these.

(Circular structure represented by general formula (22))
The cyclic structure represented by the general formula (22) will be described below.

In the general formula (22), X ² represents CR ¹³ R ¹⁴ , NR ¹⁵ , an oxygen atom or a sulfur atom. X ² is preferably a ^CR 13 ^{R 14, NR 15,} and more preferably CR ¹³ R 14, ^{NR 15.}

Y ² represents a carbon atom, a nitrogen atom or a sulfur atom, preferably a carbon atom or a sulfur atom, and more preferably a carbon atom.

Y ³ represents CR ¹⁶ R ¹⁷ , NR ¹⁸ , an oxygen atom, a sulfur atom, —C (═O) —, —N (═O) — or S (═O) —, and —S (═O) —. , —C (═O) — is preferable, and —C (═O) — is more preferable.

R ^{2 to} R ¹⁸ represent a hydrogen atom or a monovalent substituent, and more preferably a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms.

  k1, m1, and n1 each independently represents an integer of 0-2. k1 is preferably 0 or 1, and more preferably 0. m1 is preferably 0 or 1. n1 is preferably 0 or 1. More preferably, the sum of m1 and n1 is 0 or 1.

  The k1 partial structure, the m1 partial structure, and the n1 partial structure are joined in any order.

  The cyclic structure represented by the general formula (22) may form an aromatic ring, a hetero ring, or an aromatic hetero ring as a whole. Moreover, although the some cyclic structure may be included, it is preferable that it is a single cyclic structure.

As a preferable combination of X ² , Y ² , Y ³ , R ^{2 to} R ¹⁸ , k1, m1 and n1, X ² is NR ¹⁵ , Y ² is a carbon atom, and Y ³ is —C (═O )-, R ^{2 to} R ¹⁸ are hydrogen atoms, k1 is 0, m1 is 0 or 1, and n1 is 0 or 1, and is represented by the general formula (25). A structure is more preferable.

  (Circular structure represented by general formula (25))

In the general formula (25), R ²¹ is a hydrogen atom, a group represented by the following general formula (25-1), a group represented by the following general formula (25-2), or a C 1-8 substitution or An unsubstituted alkyl group is represented.

R ^{31 to} R ⁴⁷ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms that may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. And an atom or group selected from the group consisting of polar groups.

In formula (25-1), the p1 and q1 is 0 or a positive integer, when p1 = q1 = ^{0, R 32} and ^{R 35} or ^{R 35} and ^{R 39} may have a hetero atom bonded to each other A monocyclic or polycyclic group may be formed.

  In general formula (25-2), s is 0 or an integer of 1 or more.

R ^{22 to} R ²⁹ represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, preferably a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, and more preferably a hydrogen atom. .

  m2 and n2 each represents 0 or 1.

  Although the specific example of the cyclic structure represented by the said General formula (22) or (25) is given, it is not limited to these.

  As the polymer having negative intrinsic birefringence, a styrene polymer is also preferable.

  The styrenic polymer is preferably a structural unit obtained from an aromatic vinyl monomer represented by the following general formula (31).

In the formula, each of R ^{101 to} R ¹⁰⁴ independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. Represents a hydrocarbon group of 1 to 30 or a polar group, and R ¹⁰⁴ may be the same atom or group or different atoms or groups, and may be bonded to each other to form a carbocyclic or heterocyclic ring ( These carbocycles and heterocycles may form a monocyclic structure, or other rings may be condensed to form a polycyclic structure.

  Specific examples of the aromatic vinyl monomer include styrene; α-methylstyrene; β-methylstyrene; alkyl-substituted styrenes such as o-methylstyrene, m-methylstyrene, and p-methylstyrene; 4-chlorostyrene Halogen substituted styrenes such as 4-bromostyrene; o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3,4-dihydroxy Hydroxystyrenes such as styrene; vinyl benzyl alcohols; alkoxy-substituted styrenes such as p-methoxystyrene, p-tert-butoxystyrene, m-tert-butoxystyrene; 3-vinylbenzoic acid, 4-vinylbenzoic acid, etc. Vinylbenzoic acids; methyl-4-vinyl Vinyl benzoates such as benzoate, ethyl-4-vinylbenzoate; 4-vinylbenzyl acetate; 4-acetoxystyrene; amide styrenes such as 2-butylamidostyrene, 4-methylamidostyrene, p-sulfonamidostyrene; Aminostyrenes such as 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline and vinylbenzyldimethylamine; Nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; 3-cyanostyrene, 4-cyanostyrene Cyanostyrenes such as; vinyl phenylacetonitrile; aryl styrenes such as phenylstyrene; and indenes, but the present invention is not limited to these specific examples. Two or more of these monomers may be used as a copolymerization component. Of these, styrene and α-methylstyrene are preferred because they are easily available industrially and are inexpensive.

(Acrylic polymer)
As the polymer having negative intrinsic birefringence, an acrylic polymer is also preferable.

  The acrylic polymer is preferably a structural unit obtained from an acrylate ester monomer represented by the general formula (32).

In the formula, each of R ^{105 to} R ¹⁰⁸ independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. This represents a hydrocarbon group of 1 to 30 or a polar group.

  Examples of the acrylate monomer include, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, tert-). , Pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), acrylic acid Nonyl (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2- Hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid (2-methoxyethyl) Acrylic acid (2-ethoxyethyl) phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl), acrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), Methacrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), acrylic acid (o or m or p-tolyl), methacrylic acid (o or m or p-tolyl), benzyl acrylate, benzyl methacrylate, phenethyl acrylate, Phenethyl methacrylate, acrylic acid (2-naphthyl), cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl), acrylic acid (4-ethylcyclohexyl), methacrylic acid ( 4-Eth (Lucyclohexyl) and the like, or those obtained by replacing the acrylic ester with a methacrylic ester, but the present invention is not limited to these specific examples. Two or more of these monomers may be used as a copolymerization component. Of these, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, tert-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), or those obtained by replacing the above acrylate esters with methacrylate esters are preferred.

(Copolymer)
The polymer having negative intrinsic birefringence may be a copolymer unless it is contrary to the gist of the present invention. Moreover, when it is a copolymer, it may be a block copolymer or a random polymer. Moreover, a graft copolymer may be sufficient.

  The polymer having the cyclic structure represented by the general formula (21) or (22) in the side chain is a monomer having the cyclic structure represented by the general formula (21) or (22) in the side chain. Even if it is a polymer, it may be a copolymer of a monomer having a cyclic structure represented by two or more of the above general formulas (21) or (22) in the side chain. Or the copolymer of the monomer which has the cyclic structure represented by (22) in a side chain, and another monomer may be sufficient.

  The other monomers are not particularly limited, and examples thereof include acrylic acid, methacrylic acid, alkyl esters of acrylic acid (such as methyl acrylate and ethyl acrylate), alkyl esters of methacrylic acid (such as methyl methacrylate and ethyl methacrylate), and acrylic acid. Hydroxyalkyl esters (such as hydroxyethyl acrylate), hydroxyalkyl esters of methacrylic acid (such as hydroxyethyl methacrylate), aminoalkyl esters of acrylic acid (such as diethylaminoethyl acrylate), aminoalkyl esters of methacrylic acid, monoesters of acrylic acid and glycol Esters, monoesters of methacrylic acid and glycol (such as hydroxyethyl methacrylate), alkali metal salts of acrylic acid, alkali gold of methacrylic acid Salt, ammonium salt of acrylic acid, ammonium salt of methacrylic acid, quaternary ammonium derivative of aminoalkyl ester of acrylic acid, quaternary ammonium derivative of aminoalkyl ester of methacrylic acid, fourth of diethylaminoethyl acrylate and methyl sulfate Quaternary ammonium compounds, vinyl methyl ether, vinyl ethyl ether, alkali metal salts of vinyl sulfonic acid, ammonium salts of vinyl sulfonic acid, styrene sulfonic acid, styrene sulfonate, allyl sulfonic acid, allyl sulfonate, methallyl sulfonic acid, Methallyl sulfonate, vinyl acetate, vinyl stearate, N-vinylimidazole, N-vinylacetamide, N-vinylformamide, N-vinylcaprolactam, N-vinylcarbazole, acrylic Amide, methacrylamide, N- alkylacrylamide, may be mentioned N- methylolacrylamide, N, N- methylenebisacrylamide, glycol diacrylate, glycol dimethacrylate, divinylbenzene, and glycol diallyl ether. Among these, vinyl acetate, acrylic acid, methacrylic acid, and methyl methacrylate are preferable, vinyl acetate and hydroxyalkyl ester of methacrylic acid are more preferable, and hydroxyalkyl ester of methacrylic acid is particularly preferable.

  When the substitution degree of the cellulose acetate resin is high, the cellulose acetate resin has increased hydrophobicity. Therefore, the monomer having the cyclic structure represented by the general formula (21) or (22) in the side chain is used as another monomer. It is preferable to increase the hydrophobicity and improve the compatibility as a copolymer.

  On the contrary, when the substitution degree of the cellulose acetate resin is low, the hydrophobicity of the cellulose acetate resin is lowered, and thus the monomer having the cyclic structure represented by the general formula (21) or (22) in the side chain. It is preferable to reduce the hydrophobicity as a copolymer with other monomers to improve the compatibility. For example, when a vinylpyrrolidone homopolymer is used as a polymer having a cyclic structure represented by the general formula (21) or (22) in the side chain, the vinylpyrrolidone homopolymer is hydrophilic and thus highly substituted. The compatibility with the cellulose acetate resin of the degree is not good. Therefore, for example, by using a copolymer of polyvinylpyrrolidone and polyvinyl acetate and adjusting the copolymerization ratio, the hydrophilicity / hydrophobicity can be adjusted according to the degree of substitution of the cellulose acetate resin. By adjusting the compatibility in this manner, it is possible to suppress crying and whitening of the obtained cellulose acetate laminated film, which is preferable.

  When the monomer having the cyclic structure represented by the general formula (21) or (22) in the side chain is a copolymer with another monomer, the monomer is represented by the general formula (21) or (22). The copolymerization ratio of the monomer having a cyclic structure in the side chain and the other polymer monomer is preferably 3: 7 to 9: 1, more preferably 3: 7 to 7: 3. : 5-7: 3 is particularly preferable.

  When the polymer having negative intrinsic birefringence is a copolymer, the aromatic vinyl monomer represented by the general formula (31) and the acrylate ester represented by the general formula (32) Those containing at least one structural unit obtained from a monomer are also preferred.

In the formula, each of R ^{101 to} R ¹⁰⁴ independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. Represents a hydrocarbon group of 1 to 30 or a polar group, and R ¹⁰⁴ may be the same atom or group or different atoms or groups, and may be bonded to each other to form a carbocyclic or heterocyclic ring ( These carbocycles and heterocycles may form a monocyclic structure, or other rings may be condensed to form a polycyclic structure.

In the formula, R ^{105 to} R ¹⁰⁸ each independently have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom, and the number of substituted or unsubstituted carbon atoms 1-30 hydrocarbon groups or a polar group is represented.

  Further, the structure other than the above constituting the copolymer composition is preferably excellent in copolymerizability with the monomer, and examples thereof include maleic anhydride, citraconic anhydride, cis-1-cyclohexene-1 , 2-dicarboxylic anhydride, 3-methyl-cis-1-cyclohexene-1,2-dicarboxylic anhydride, 4-methyl-cis-1-cyclohexene-1,2-dicarboxylic anhydride and the like, acrylonitrile, Nitrile group-containing radical polymerizable monomers such as methacrylonitrile; amide bond-containing radical polymerizable monomers such as acrylamide, methacrylamide, trifluoromethanesulfonylaminoethyl (meth) acrylate; fatty acid vinyls such as vinyl acetate; Chlorine-containing radical polymerizable monomers such as vinyl and vinylidene chloride; 1,3-butadiene; Isoprene, 1,4-dimethyl butadiene and the like can be mentioned conjugated diolefins but the present invention is not limited thereto. Of these, styrene-acrylic acid copolymers, styrene-maleic anhydride copolymers, and styrene-acrylonitrile copolymers are particularly preferred.

  In the cellulose acetate laminated film of the present invention, the compound having negative intrinsic birefringence is preferably a styrene polymer from the viewpoint of further improving the wet heat durability of optical properties. In addition, it is preferable that the styrenic polymer is a styrene-maleic anhydride copolymer from the viewpoint of further improving the wet heat durability of optical characteristics.

  The addition amount of the compound having negative intrinsic birefringence is preferably 0.5 to 40 parts by mass, more preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the cellulose acetate resin. 1 to 20 parts by mass is more preferable.

  In the cellulose acetate laminated film of the present invention, the content of the compound having negative intrinsic birefringence contained in the core layer and skin A layer is 5% or more and less than 50% with respect to cellulose acetate. It is preferable from the viewpoint of maintaining durability of optical characteristics under conditions.

  The cellulose acetate laminated film of the present invention may or may not contain a compound having negative intrinsic birefringence in the skin B layer, but includes a compound having negative intrinsic birefringence in the skin B layer. In this case, the content thereof is preferably 5% or less, more preferably less than 3%, and particularly preferably less than 2% with respect to cellulose acetate.

  When the compound having negative intrinsic birefringence is a polymer having negative intrinsic birefringence, the weight average molecular weight is preferably 500 to 100,000, and preferably 700 to 50,000. More preferred is 1,000 to 25,000.

  If the molecular weight is 500 or more, the volatility is good, and if the molecular weight is 100,000 or less, the compatibility with the cellulose acetate resin is good, so the film forming property of the cellulose acetate laminated film is good, both of which are preferable. .

<Other additives>
In the present invention, deterioration inhibitors, ultraviolet absorbers, peeling accelerators, matting agents, lubricants, the aforementioned plasticizers, and the like can be appropriately used as necessary.

(Deterioration inhibitor)
In the present invention, a known deterioration (oxidation) inhibitor such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-) is added to the cellulose acetate solution. 3-methylphenol), 1,1'-bis (4-hydroxyphenyl) cyclohexane, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, penta A phenolic or hydroquinone antioxidant such as erythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert) It is preferable to use a phosphorus-based antioxidant such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The addition amount of the deterioration inhibitor is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the cellulose resin.

(UV absorber)
In the present invention, an ultraviolet absorber is preferably used for the cellulose acetate solution from the viewpoint of preventing deterioration of a polarizing plate or liquid crystal. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. Examples of hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Examples of benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5- Triazine, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4- Hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, (2- (2'-hydroxy-3', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] The addition amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio in the entire optical film.

(Matting agent fine particles)
The cellulose acetate laminated film of the present invention preferably contains metal fine particles and an amine-based dispersant in at least one of the skin A layer and the skin B layer.

  By adding the matting agent, the slipping property is improved, which is preferable in terms of production suitability when continuously producing a long cellulose acetate film.

  As metal fine particles used as a matting agent, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Mention may be made of magnesium silicate and calcium phosphate.

  As the metal fine particles, those 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 diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm can reduce the haze of the film, and are more preferable. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter 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 about 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, and are present on the film surface in an amount of 0.00. Unevenness of about 1 to 3.0 μm is formed. The secondary average particle diameter is preferably about 0.2 μm to 1.5 μm, more preferably about 0.4 μm to 1.2 μm, and further preferably about 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.

  As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  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 / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

A fine particle dispersion can be used in the method for producing a cellulose acetate film having particles having a small secondary average particle size. Several methods are conceivable when preparing a dispersion of fine particles. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are mixed with stirring in advance, adding this fine particle dispersion to a small amount of a separately prepared cellulose acetate solution, stirring and dissolving, and further mixing with the main cellulose acetate dope solution There is. This method is a preferable 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, a small amount of cellulose acetate is added to the solvent, dissolved by stirring, then 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 mixed with the dope solution using an in-line mixer. There is also a method of mixing well. Any method may be used, and the present invention is not limited to these methods. The concentration of silicon dioxide when the silicon dioxide fine particles are mixed with a solvent and dispersed is preferably about 5 to 30% by mass, more preferably about 10 to 25% by mass, and still more preferably about 15 to 20% by mass. 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 acetate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and more preferably 0.08 to 0.16 g per 1 m ^2. More preferred.

  The solvent used in the above preparation method 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 formation of a cellulose acetate.

  The amount of the matting agent contained in the cellulose acetate of the present invention is preferably 0.03 to 0.1% by mass, and 0.05 to 0.08% by mass with respect to the total mass of the cellulose acetate. It is more preferable. If the content of the matting agent is large, the haze increases, which is not preferable. If the content is too small, the slipping property of the film is deteriorated, and the occurrence of creaking and scratches during conveyance becomes a problem. According to the production method of the present invention described later, even when a film is produced using a cellulose acetate composition containing a relatively large amount of matting agent, the haze increase of the film can be suppressed. A satisfactory film can be stably produced.

(Amine dispersant)
In this invention, it is preferable to use 1 type, or 2 or more types chosen from an amine type dispersing agent and a carboxy-group containing polymer dispersing agent as a dispersing agent.

  In particular, the cellulose acetate laminated film of the present invention preferably contains an amine-based dispersant in at least one of the skin A layer and the skin B layer.

  As the amine dispersant, at least one dispersant among alkylamine and amine salt of polycarboxylic acid is preferable. For example, polyester acid, polyether ester acid, fatty acid, fatty acid amide, polycarboxylic acid, alkylene oxide, polyalkylene oxide, polyoxyethylene fatty acid ester, polyoxyethylene glycerin fatty acid ester, and derivatives thereof are aminated. Can be mentioned. Examples of amine salts include amidoamine salts, aliphatic amine salts, aromatic amine salts, alkanolamine salts, and polyvalent amine salts. Specific examples include polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, tripropylamine, diethylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine and the like.

  Specific examples include Solspers series (manufactured by Lubrizol), Ajisper series (manufactured by Ajinomoto Co., Inc.), BYK series (manufactured by Big Chemie), and EFKA series (manufactured by EFKA). In addition, when a dispersant such as a surfactant type is used, the adsorption to the surface of the conductive component is insufficient compared to the polymer dispersant, and the particles may easily reaggregate. The dispersant is expensive, and since the molecular weight is lower than that of the binder resin, it is desirable to keep the addition amount small. However, if the amount of the dispersant is too small, poor wetting of the conductive component and a decrease in dispersion stability are caused. As addition amount, 0.05-10 mass parts is preferable with respect to 10 mass parts of silicon oxide fine particles.

  As the carboxy group-containing polymer dispersant, at least one of a polycarboxylic acid and a salt thereof is preferable. For example, polycarboxylic acid, ammonium polycarboxylate, sodium polycarboxylate and the like can be mentioned. Specific examples include polyacrylic acid, ammonium polyacrylate, sodium polyacrylate, ammonium polyacrylate copolymer, polymaleic acid, ammonium polymaleate, and sodium polymaleate.

  These amine dispersants and carboxy group-containing polymer dispersants can be used in the form of a solution dissolved in a solvent component, or commercially available ones can also be used. The addition amount of these amine-based dispersant and / or carboxy group-containing polymer dispersant may be appropriately adjusted according to the use of the titanium oxide dispersion and the type of the dispersant, but is not more than 0. It is preferable that it is 2 mass% or more. When the addition amount of the dispersing agent is less than 0.2% by mass with respect to the matting agent, an effect sufficient to improve the dispersibility of the matting agent cannot be obtained.

(Peeling accelerator)
It is preferable that the film of the present invention contains a release accelerator from the viewpoint of more releasability. The peeling accelerator can be included at a ratio of 0.001 to 1% by mass, for example, and the addition of 0.5% by mass or less is preferable because separation of the release agent from the film hardly occurs. 005% by mass or more is preferable because a desired peeling reduction effect can be obtained. Therefore, it is preferably included at a rate of 0.005 to 0.5% by mass, and at a rate of 0.01 to 0.3% by mass. More preferably. As the peeling accelerator, known ones can be employed, and organic and inorganic acidic compounds, amine compounds, surfactants, chelating agents and the like can be used. Among them, polyvalent carboxylic acids and esters thereof, and amine compounds are effective, and the amine dispersant can be effectively used for the peelability of the film in addition to the dispersing effect of the matting agent. .

(Explanation of dope preparation, physical properties, size, etc.)
When the matting agent is added to the cellulose acetate solution, the method is not particularly limited, and any method can be used as long as a desired cellulose acetate solution can be obtained.

  For example, an additive may be included at the stage of mixing cellulose acetate and a solvent, or an additive may be added after preparing a mixed solution with cellulose acetate and a solvent. Further, it may be added and mixed immediately before casting the dope, which is a so-called immediately preceding addition method, and the mixing is used by installing screw-type kneading online. Specifically, a static mixer such as an inline mixer is preferable.

  As for in-line addition, in order to eliminate concentration unevenness, particle aggregation, etc., Japanese Patent Application Laid-Open No. 2003-053752 adds an additive solution having a different composition to the main raw material dope in a method for producing a cellulose acetate film. There is described an invention in which the distance L between the nozzle tip and the starting end portion of the in-line mixer is 5 times or less of the main raw material pipe inner diameter d, thereby eliminating concentration unevenness, matting particles and the like. As a more preferred embodiment, the distance (L) between the tip opening of the additive liquid supply nozzle having a composition different from that of the main raw material dope and the starting end of the in-line mixer is 10 times or less the inner diameter (d) of the supply nozzle tip opening. The in-line mixer is a static non-stirring type in-tube mixer or a dynamic stirring type in-tube mixer. More specifically, it is disclosed that the flow rate ratio of the cellulose acetate film main raw material dope / in-line additive solution is 10/1 to 500/1, preferably 50/1 to 200/1. Furthermore, the additive is also added to Japanese Patent Application Laid-Open No. 2003-014933 of the invention aiming at a retardation film with little additive bleed-out, no delamination phenomenon, excellent slipperiness and excellent transparency. As a method to do this, it may be added to the melting pot, or a solution in which additives or additives are dissolved or dispersed between the melting pot and the co-casting die may be added to the dope being fed. However, in the latter case, it is described that it is preferable to provide a mixing means such as a static mixer in order to improve the mixing property.

  The film of the present invention contains a matting agent in the skin B layer, and is resistant to scratches by reducing the coefficient of friction on the film surface. It is preferable from the viewpoint of prevention, and from the viewpoint of film haze, it is more preferable not to include a matting agent in the skin A layer.

  In the film of the present invention, when the matting agent is not added in a large amount, the haze of the film does not increase, and when actually used in an LCD, inconveniences such as a decrease in contrast and generation of bright spots are unlikely to occur. If the amount is too small, the above-mentioned creaking and scratch resistance can be realized. From these viewpoints, it is preferably included at a ratio of 0.01 to 5.0 mass%, more preferably included at a ratio of 0.03 to 3.0 mass%, and a ratio of 0.05 to 1.0 mass% It is particularly preferable to include

(Haze)
The optical film of the present invention preferably has a haze of less than 1%, more preferably less than 0.5%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as an optical film.

(Average moisture content)
In the film of the present invention, the equilibrium water content at 25 ° C. and 60% relative humidity is preferably 4% or less, more preferably 3% or less. By setting the average moisture content to 4% or less, it is easy to cope with changes in humidity, and the optical characteristics and dimensions are more difficult to change.

(Re, Rth)
When the retardation value of the film of the present invention is used for a retardation film, Re and Rth are appropriately selected depending on the design of the liquid crystal cell and the optical film. In general, Re is 25 nm ≦ | Re | It is preferable that ≦ 100 nm and the retardation Rth in the film thickness direction is 50 nm ≦ | Rth | ≦ 250 nm. The Re is more preferably 30 nm ≦ | Re | ≦ 80 nm, and particularly preferably 35 nm ≦ | Re | ≦ 70 nm. The Rth is more preferably 70 nm ≦ | Rth | ≦ 240 nm, and particularly preferably 90 nm ≦ | Rth | ≦ 230 nm.

  Re (λ) and Rth (λ) in the present application represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. In the present application, the wavelength λ is 590 nm unless otherwise specified.

  Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments).

  Rth (λ) is the value of Re (λ) with the in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotary axis) (if there is no slow axis, any in-plane The rotation axis is the rotation axis.) With respect to the normal direction of the film, from the normal direction to 50 degrees on one side, the light of wavelength λ nm is incident from each inclined direction in steps of 10 degrees, and a total of 6 points are measured. KOBRA 21ADH calculates based on the measured retardation value, the assumed average refractive index, and the input film thickness value.

  The retardation value is measured from any two directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), and the value Rth can also be calculated based on the assumed average refractive index and the input film thickness value.

  Here, 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 main optical films are exemplified below: cellulose acetate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59).

By inputting the assumed average refractive index values and thicknesses, KOBRA 21ADH calculates the _{n x, n y, n z} .

The calculated _{n x, n y, n z} from _{N z = (n x -n z} ) / (n x -n y) is further calculated.

  Here, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. d represents the film thickness.

Rth = ((n _x + n _y ) / 2−n _z ) × d
At this time, an average refractive index n is required as a parameter, and a value measured by an Abbe refractometer (“Abbe refractometer 2-T” manufactured by Atago Co., Ltd.) was used.

(Nz coefficient)
In the film of the present invention, the Nz coefficient represented by the following formula (3) is appropriately selected depending on the design of the liquid crystal cell, the optical film, and the like, but is generally preferably 7 or less. More preferably, it is more preferably 4.5 or less.

Formula (3): Nz coefficient = Rth / Re + 0.5
(Film thickness)
In the film of the present invention, the average thickness of the core layer is preferably 30 to 100 μm, more preferably 30 to 80 μm, and further preferably 30 to 70 μm. By setting it to 30 μm or more, the handling property when producing a web-like film is improved, which is preferable. Moreover, by setting it as 70 micrometers or less, it is easy to respond to a humidity change and it is easy to maintain an optical characteristic.

  The film of the present invention may have an average film thickness of at least one of the skin A layer or the skin B layer of 0.2% or more and less than 25% of the average film thickness of the core layer. If it is less than 25%, the optical performance of the core layer can be effectively utilized, and the laminate film can be effectively used. Is preferable from the viewpoint of obtaining sufficient optical characteristics, more preferably 0.5 to 15%, and particularly preferably 1.0 to 10%. Moreover, it is more preferable that the average film thickness of the skin A layer and the skin B layer are both 0.2% or more and less than 25% of the average core layer film thickness.

(Film width)
The film of the present invention preferably has a film width of 700 to 3000 mm, more preferably 1000 to 2800 mm, and particularly preferably 1500 to 2500 mm.

[Method for producing cellulose acetate laminated film]
The method for producing a cellulose acetate laminated film of the present invention (hereinafter also referred to as “manufacturing method according to the present invention”) satisfies the above formula (1) and a dope containing cellulose acetate that satisfies the above formula (2). A step of multilayer casting a dope containing cellulose acetate on the support in this order simultaneously or sequentially, a step of drying the multilayer cast dope and peeling from the support, and a film after peeling And a retardation adjusting agent is added to at least one of the core layer dope and the skin B layer dope.

(Preparation of dope)
Specifically, in the production method according to the present invention, the film of the present invention is produced using a solution (dope) obtained by dissolving cellulose acetate in an organic solvent by a solvent cast method.

  The organic solvent is selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to include a solvent. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone, and ester (that is, —O—, —CO—, and COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxy group (hydroxyl group). In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.

  Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.

  Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.

  Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon.

  Two or more organic solvents may be mixed and used.

  A cellulose acetate solution can be prepared by a general method. A general method means processing at a temperature of 0 ° C. or higher (ordinary temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent.

  The amount of cellulose acetate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).

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

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

  When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.

  It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.

  Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

  A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, cellulose acetate can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose acetate by a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method.

  In the cooling dissolution method, first, cellulose acetate is gradually added with stirring to an organic solvent at room temperature. The amount of cellulose acetate is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.

  The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). When cooled in this way, the mixture of cellulose acetate and organic solvent solidifies.

  The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The faster the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling to the final cooling temperature.

  Furthermore, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), cellulose acetate is dissolved in the organic solvent. The temperature can be raised by simply leaving it at room temperature or in a warm bath. The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. .

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

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

(Co-casting)
A cellulose acylate film can be produced from the prepared two or more kinds of cellulose acetate solutions (dope) by a solvent cast method.

  The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35% by mass. The surface of the drum or band is preferably finished in a mirror state.

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

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

  In the present invention, the obtained cellulose acetate solution (dope) is formed by casting the two or more kinds of cellulose acetate solutions on a smooth band or drum as a support.

  There is no restriction | limiting in particular as a manufacturing method of the film of this invention other than the above, A well-known co-casting method can be used. For example, a film may be produced by laminating and laminating a solution containing cellulose acetate from a plurality of casting ports provided at intervals in the traveling direction of the metal support. The methods described in JP-A Nos. 158414, 1-122419, and 11-198285 can be applied. Further, it may be formed into a film by casting a cellulose acetate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933.

  A cellulose acetate film in which a flow of a high-viscosity cellulose acetate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acetate solution and the high- and low-viscosity cellulose acetate solution is simultaneously extruded. A casting method may be used. Furthermore, it is also a preferred embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution.

  Alternatively, by using two casting ports, the film cast on the metal support is peeled off by the first casting port, and the second casting is performed on the side in contact with the metal support surface. Further, a film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235.

  The cellulose acetate solution to be cast may be the same solution or different cellulose acetate solutions, and is not particularly limited. In order to give a function to a plurality of cellulose acetate layers, a cellulose acetate solution corresponding to the function may be extruded from each casting port.

  Furthermore, the cellulose acetate solution according to the present invention can be simultaneously cast with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorption layer, a polarizing layer). . As a method for producing the film of the present invention, it is preferred that the film formation is simultaneous or sequential multilayer casting film formation.

  In the conventional single-layer liquid, it is necessary to extrude a high-concentration and high-viscosity cellulose acetate solution in order to obtain the required film thickness. In many cases, this causes a problem such as a fault or flatness. As a solution to this, by casting a plurality of cellulose acetate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also a reduction in drying load can be achieved by using a concentrated cellulose acetate solution, and the production speed of the film can be increased.

  In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 0.2 to 50% of the total film thickness, more preferably 2 to 30%. . Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness.

  In the case of co-casting, a cellulose acetate film having a laminated structure can be produced by co-casting cellulose acetate solutions having different additive concentrations such as the plasticizer, ultraviolet absorber, and matting agent. For example, a cellulose acetate film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer.

  In addition, the kind of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect that a release agent is contained only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer.

  Further, the viscosity of the solution containing cellulose acetate at the time of casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity of the layer.

  In the present invention, the multi-layer cast dope is dried and peeled from the support.

(Drying process)
A method for drying a web which has been dried on a drum or belt and peeled off will be described. The web peeled at the peeling position just before the drum or belt makes one round is conveyed by alternately passing through a group of rolls arranged in a staggered manner, or the both ends of the peeled web are gripped by clips or the like and are not contacted. It is conveyed by the method of conveying it automatically. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds. In the drying process after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferred. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, but may be appropriately selected according to the type and combination of the solvents used. In the production of the film of the present invention, the web (film) peeled from the support is preferably stretched when the amount of residual solvent in the web is less than 120% by mass.

  The residual solvent amount can be expressed by the following formula.

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

(Stretching)
The manufacturing method which concerns on this invention includes the process of extending | stretching the film after peeling after the process of drying the dope which carried out multilayer casting, and peeling from a support body.

  In the present invention, the solution cast film can be stretched without being heated to a high temperature as long as the residual solvent amount is in a specific range, but it is preferable because drying and stretching can shorten the process. . That is, the stretching process may be performed in a state where the solvent remains, or the stretching process after drying may be performed. However, if the temperature of the web is too high, the plasticizer will volatilize, so a range of 120 to 180 ° C is preferred. In addition, stretching in biaxial directions perpendicular to each other is an effective method for bringing the refractive indexes Nx, Ny, and Nz of the film within the scope of the present invention.

  For example, in the case of stretching in the casting direction, if the shrinkage in the width direction is too large, the value of Nz becomes too large. In this case, it can be improved by suppressing the width shrinkage of the film or stretching in the width direction. When stretching in the width direction, the refractive index may be distributed with a width. This is sometimes seen when using, for example, the tenter method, but it is a phenomenon that occurs when the film is stretched in the width direction and contraction force is generated at the center of the film and the end is fixed. It is thought to be called the Boeing phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed, and the distribution of the width retardation can be improved.

  Furthermore, the film thickness fluctuation | variation of the film obtained by extending | stretching in the biaxial direction orthogonal to each other can be reduced. If the film thickness variation of the optical film is too large, the retardation will be uneven. The film thickness variation of the optical film is preferably in the range of ± 3%, and more preferably ± 1%. For the purposes as described above, a method of stretching in the biaxial directions orthogonal to each other is effective, and the stretching ratios in the biaxial directions orthogonal to each other are 1.2 to 2.0 times and 0.7 to 1.0, respectively. It is preferable that the range be doubled. Here, stretching to 1.2 to 2.0 times with respect to one direction and making the other perpendicular to 0.7 to 1.0 times means that the distance between the clip or pin supporting the film is This means that the distance is 0.7 to 1.0 times the interval before stretching.

  In general, when a biaxial stretching tenter is used to stretch in the width direction so as to have an interval of 1.2 to 2.0 times, a contracting force acts in the longitudinal direction that is the perpendicular direction.

  Therefore, if the force is applied in only one direction and the stretching is continued, the width in the perpendicular direction is reduced, but this means that the amount of shrinkage is suppressed with respect to the amount that shrinks without restricting the width. This means that the interval between the clip or pin whose width is restricted is restricted to a range of 0.7 to 1.0 times that before stretching.

  At this time, in the longitudinal direction, a force is exerted to shrink the film by stretching in the width direction. By taking the interval between the clips or pins in the longitudinal direction, an excessive tension is not applied in the longitudinal direction. There is no particular limitation on the method of stretching the web.

  For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction between the rolls. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination.

  That is, the film may be stretched in the transverse direction, longitudinally, or in both directions with respect to the film forming direction, and when stretched in both directions, simultaneous stretching or sequential stretching may be used. May be. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  Moreover, it is preferable that the manufacturing method which concerns on this invention includes the process of extending | stretching the film after the said extending | stretching process again from viewpoints, such as expansion of an optical expression area | region by reduction of optical expression property, especially Nz coefficient.

(Description of optical member)
[Polarizer]
Since the cellulose acetate film of the present invention has high optical expression, it is preferably used as a retardation film as a protective film for a polarizing plate. The polarizing plate is formed by laminating and laminating a protective film on at least one surface of the polarizer. A conventionally known polarizer can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film is treated with a dichroic dye such as iodine and stretched.

  The bonding of the cellulose acetate film and the polarizer (also referred to as “polarizing film”) is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. As this water-soluble polymer adhesive, a completely saponified (saponified) polyvinyl alcohol aqueous solution is preferably used.

In this embodiment, the radiation curable composition used as an adhesive is for bonding the first and second protective layers and the polarizer. The radiation curable composition can contain the following (a) to (c) and other optional components.
(A): Alicyclic epoxy compound (b): Compound containing at least one hydroxy group (hydroxyl group) and having a number average molecular weight of 500 or more (c): Photoacid generator Hereinafter, each component will be described in detail. .

Component (a):
Component (a) constituting the radiation curable composition is an alicyclic epoxy compound, preferably an alicyclic epoxy compound having two or more alicyclic epoxy groups in one molecule. When an alicyclic epoxy compound having two or more alicyclic epoxy groups in one molecule is contained in an amount of 50% by mass or more in the total amount of the component (a), a good curing rate and mechanical strength can be maintained.

  Specific examples of the alicyclic epoxy compound used as the component (a) include 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5 -Spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6 -Methylcyclohexyl-3 ', 4'-epoxy-6'-methylcyclohexanecarboxylate, ε-caprolactone modified 3,4-epoxycyclohexylmethyl-3', 4'-epoxycyclohexanecarboxylate, trimethylcaprolactone modified 3,4- Epoxy cyclohexylme 3 ′, 4′-epoxycyclohexanecarboxylate, β-methyl-δ-valerolactone modified 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane) , Ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylenebis (3,4-epoxycyclohexanecarboxylate), dioctyl epoxycyclohexahydrophthalate, di-2-ethylhexyl epoxycyclohexahydrophthalate, etc. Can be mentioned.

  Among these alicyclic epoxy compounds, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, ε-caprolactone modified 3,4-epoxy Cyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, trimethylcaprolactone modified 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, β-methyl-δ-valerolactone modified 3,4-epoxy More preferred is cyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl-3', 4'-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexane Cyclohexylmethyl) adipate is more preferable.

  These commercially available products include Celoxide 2021, Celoxide 2021P, Celoxide 2081, Celoxide 2083, Celoxide 2085, Epolide GT-300, Epolide GT-301, Epolide GT-302, Epolide GT-400, Epolide 401, Epolide 403 (or more, Daicel Chemical Industries, Ltd.).

  The content of the alicyclic epoxy compound in the radiation curable composition is preferably 10 to 80% by mass, more preferably 12 to 75% by mass, and particularly preferably 15 to 70% by mass. When the content is less than 10% by mass, the mechanical strength and heat resistance of the adhesive layer tend to be insufficient. When this content rate exceeds 80 mass%, there exists a tendency for deformation | transformation, such as curvature of the adhesive bond layer formed by hardening | curing a radiation-curable composition, to become large.

Component (b):
Component (b) constituting the radiation curable adhesive composition is a compound containing one or more hydroxy groups (hydroxyl groups) and having a number average molecular weight of 500 or more.

  Component (b) has one or more, preferably 1 to 4, hydroxy groups (hydroxyl groups) in one molecule. The number average molecular weight of the component (b) is 500 or more, preferably 1,000 or more, more preferably 1,500 or more. The upper limit of the average molecular weight is not particularly limited, but is preferably 20,000, more preferably 10,000 from the viewpoint of preventing an excessive increase in the viscosity of the adhesive composition. When the average molecular weight is less than 500, the cutting resistance at the time of cutting the polarizing plate is inferior, which is not preferable. The number average molecular weight of the component (b) is a value measured according to ASTM D2503. By using the component (b), a laminated film having excellent adhesive strength can be obtained.

  Examples of the compound suitably used as the component (b) include polycaprolactone diol, polyether diol, polyester diol, and other polyols.

  Examples of the polycaprolactone diol include polycaprolactone diol obtained by reacting ε-caprolactone with a diol.

  Examples of the diol used here include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, neopentyl glycol, Examples include 1,4-cyclohexanedimethanol and 1,4-butanediol. Examples of commercially available products of these polycaprolactone diols include Plaxel 205, 205H, 205AL, 212, 212AL, 220, and 220AL (manufactured by Daicel Chemical Industries, Ltd.).

  The polyether diol is preferably an aliphatic polyether diol, and examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, and polydecamethylene glycol. Commercially available products of these polyether diols include PEG # 600, # 1000, # 1500, # 1540, # 4000 (above, manufactured by Lion), Exenol 720, 1020, 2020, 3020, 510, Preminol PPG4000 (above Asahi Glass Co., Ltd.).

  The polyester diol is preferably a copolymer of an aliphatic diol compound and an aliphatic dicarboxylic acid compound. Examples of the aliphatic diol compound include 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 3-methyl- 1,5-pentanediol and the like, and examples of the aliphatic dicarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid and the like.

  One or more aliphatic diols can be used, and one or more aliphatic dicarboxylic acids can be used. Commercially available products of these polyester diols include Kuraray polyol N-2010, O-2010, P-510, P-1010, P-1050, P-2010, P-2050, P-3010, P-3050 (or more, Kuraray Co., Ltd.).

  Examples of the other polyols include trihydric or higher polyhydric alcohols such as trimethylolpropane, glycerin, pentaerythritol, sorbitol, sucrose, and quadrol, ethylene oxide (EO), propylene oxide (PO), butylene oxide, tetrahydrofuran, and the like. A polyether polyol obtained by modifying with a cyclic ether compound of

  Specific examples of such compounds include EO-modified trimethylolpropane, PO-modified trimethylolpropane, tetrahydrofuran-modified trimethylolpropane, EO-modified glycerol, PO-modified glycerol, tetrahydrofuran-modified glycerol, EO-modified pentaerythritol, PO-modified pentaerythritol, Tetrahydrofuran-modified pentaerythritol, EO-modified sorbitol, PO-modified sorbitol, EO-modified sucrose, PO-modified sucrose, EO-modified sucrose, EO-modified quadrole, etc. can be exemplified, among which EO-modified trimethylolpropane, PO-modified trimethylol Propane, PO-modified glycerin and PO-modified sorbitol are preferred.

  Commercially available products of the above other polyols include Sannix TP-700, Sannix GP-1000, Sannix SP-750, Sannix GP-400, Sannix GP-600 (above, manufactured by Sanyo Chemical Co., Ltd.), etc. Can be mentioned.

  Moreover, as a polyol used suitably as a component (b), the polymer of a hydroxy group (hydroxyl group) containing unsaturated compound can be mentioned. Examples of the hydroxy group (hydroxyl group) -containing unsaturated compound include hydroxy group (hydroxyl group) -containing (meth) acrylates. Specifically, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, 2-hydroxyalkyl (meth) acryloyl phosphate, 4-hydroxycyclohexyl ( (Meth) acrylate, 1,6-hexanediol mono (meth) acrylate, neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolethanedi (meth) acrylate, pentaerythrine Ritorutori (meth) acrylate, dipentaerythritol penta (meth) acrylate. Furthermore, the compound obtained by addition reaction of glycidyl group containing compounds, such as alkyl glycidyl ether, allyl glycidyl ether, and glycidyl (meth) acrylate, and (meth) acrylic acid is mentioned.

The component (b) is also preferably a polycarbonate diol represented by the following formula (PC).
Formula (PC): HO— (R ⁶ —O—CO—O) _m — (R ⁷ —O—CO—O) _n —R ⁸ —OH
(In the formula, R ⁶ and R ⁷ each independently represent a divalent hydrocarbon group having 2 to 12 carbon atoms, R ⁸ represents the same structure as either R ⁶ or R ⁷ , and m represents 2 to 150. , N is 0 to 150, and m + n is 2 to 200.)
The method for producing the polycarbonate diol represented by the above formula (PC) is not particularly limited, and examples thereof include known methods such as a transesterification reaction between a diol compound and a carbonate compound, and a polycondensation reaction between a diol compound and phosgene. . Examples of the diol compound used for the production of component (b) include 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl. -1,8-octanediol and the like. Moreover, in order to obtain moderate adhesive strength, a polycarbonate diol containing an aliphatic hydrocarbon group having 6 carbon atoms such as 1,6-hexanediol and 3-methyl-1,5-pentanediol is more preferable.

  Examples of commercially available compounds that can be suitably used as polycarbonate diol include DN-980, 981, 982, 983 (manufactured by Nippon Polyurethane), PC-8000 (PPG), PC-THF-CD (BASF Japan). Manufactured), Kuraray polyol C-590, C-1090, C-2050, C-2090, C-3090, C-2065N, C-2015N (above, manufactured by Kuraray Co., Ltd.), Plaxel CD CD210PL, Plaxel CD CD220PL ( As mentioned above, Daicel Chemical Industries Ltd.) etc. are mentioned.

  In the composition for radiation curable adhesive, the content of the component (b) is preferably 2 to 50% by mass, more preferably 3 to 45% by mass, and particularly preferably 3 to 3% from the viewpoint of adhesive strength, viscosity, and the like. 40% by mass.

Component (c):
Component (c) constituting the radiation curable composition is a photoacid generator.

Examples of the photoacid generator include onium salts having a structure represented by the following general formula (ON). This onium salt has a substantial light absorption wavelength below 400 nm.
Formula (ON): [R ⁹ aR ¹⁰ bR ¹¹ cR ¹² dz] ^{p +} [MX _{q + p} ] ^p−
(Wherein the cation is an onium ion, Z represents S, Se, Te, P, As, Sb, Bi, O, I, Br, Cl, or N ₂ , and R ⁹ , R ¹⁰ , R ^11, and R 2) ¹² represents the same or different organic group, a, b, c and d are each an integer of 0 to 3, and (a + b + c + d−p) is equal to the valence of Z. M is a halide complex. [MX _{q + p} ] represents a metal or metalloid constituting the central atom of, for example, B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V, Cr, Mn, X is a halogen atom such as F, Cl, Br, etc., p is the net charge of the halide complex ion, and q is the valence of M.)
In the general formula (ON), specific examples of the onium ion include diphenyliodonium, 4-methoxydiphenyliodonium, bis (4-methylphenyl) iodonium, bis (4-tert-butylphenyl) iodonium, bis (dodecylphenyl). Diaryliodonium such as iodonium, triarylsulfonium such as triphenylsulfonium and diphenyl-4-thiophenoxyphenylsulfonium, bis [4- (diphenylsulfonio) -phenyl] sulfide, bis [4- (di (4- ( 2-hydroxyethyl) phenyl) sulfonio) -phenyl] sulfide, η ⁵ -2,4- (cyclopentadienyl) [1,2,3,4,5,6-η]-(methylethyl) -benzene] -Iron (1+) etc. are mentioned.

In the general formula (ON), specific examples of the anion [MX _{q + p} ] include tetrafluoroborate (BF ₄ ⁻ ), hexafluorophosphate (PF ₆ ⁻ ), hexafluoroantimonate (SbF ₆ ⁻ ), hexafluoroarce. Nate (AsF ₆ ⁻ ), hexachloroantimonate (SbCl ₆ ⁻ ) and the like.

Moreover, the onium salt which has an anion represented with general formula [ _MXq (OH) < ^- >] can be used. Further, perchlorate ion (ClO ₄ ⁻ ), trifluoromethane sulfonate ion (CF ₃ SO ₃ ⁻ ), fluorosulfonate ion (FSO ₃ ⁻ ), toluene sulfonate ion, trinitrobenzene sulfonate anion, trinitrotoluene sulfonate Onium salts having other anions such as anions can also be used.

  Examples of onium salts used as component (c) include aromatic halonium salts described in, for example, JP-A-50-151996, JP-A-50-158680, JP-A-50-151997, VIA group aromatic onium salts described in JP-A-52-30899, JP-A-56-55420, JP-A-55-125105, etc., VA described in JP-A-50-158698, etc. Aromatic aromatic onium salts, oxosulfoxonium salts described in JP-A-56-8428, JP-A-56-149402, JP-A-57-192429, etc., JP-A-49-17040 Aromatic diazonium salts described in U.S. Pat. No. 4,139,655, and thiobililium salts described in US Pat. No. 4,139,655. Moreover, an iron / allene complex, an aluminum complex / photolytic silicon compound-based initiator, and the like can also be mentioned. Photoacid generators preferably used as component (c) are aromatic onium salts such as diaryl iodonium salts and triarylsulfonium salts, and more preferably triarylsulfonium salts.

  Examples of commercially available photoacid generators include UVI-6950, UVI-6970, UVI-6974, UVI-6990 (manufactured by Union Carbide), Adekaoptomer SP-150, SP-151, SP-170. SP-172 (above, manufactured by ADEKA Corporation), Irgacure 184, Irgacure 261 (above, manufactured by BASF Japan Co., Ltd.), CI-2481, CI-2624, CI-2639, CI-2064 (above, Nippon Soda Co., Ltd.) )), CD-1010, CD-1011, CD-1012 (above, manufactured by Sartomer), DTS-102, DTS-103, NAT-103, NDS-103, TPS-103, MDS-103, MPI-103 , BBI-103 (above, manufactured by Midori Chemical Co., Ltd.), PCI-061T, PCI-06 T, PCI-020T, PCI-022T (manufactured by Nippon Kayaku Co., Ltd.), CPI-110A, CPI-101A (above, SAN-APRO Ltd.), and the like. Among these, UVI-6970, UVI-6974, Adeka optomer SP-170, SP-172, CD-1012, MPI-103, CPI-110A, CPI-101A are high in the composition containing them. It is particularly preferable because photocuring sensitivity can be expressed. Said photo-acid generator can be used individually by 1 type or in combination of 2 or more types.

  A sensitizer may be used in combination in order to promote the generation of acid by the photoacid generator. Examples of the sensitizer include dihydroxybenzene, trihydroxybenzene, hydroxyacetophenone, dihydroxydiphenylmethane, and the like.

  In the radiation curable composition, the content of the photoacid generator is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and particularly preferably 0.3 to 3% by mass. . When the content is less than 0.1% by mass, the radiation curability of the radiation curable composition is lowered, and an adhesive layer having sufficient mechanical strength cannot be formed. If the content exceeds 10% by mass, the photoacid generator may adversely affect the long-term characteristics of the adhesive layer, which is not preferable.

  The manufacturing method of the polarizing plate according to the present invention includes (a) a polarizer and a first cellulose acetate film formed on the first surface of the polarizer, and the polarizer and the polarizer. A step of supplying a radiation-curable adhesive composition between the second cellulose acetate laminated film formed on the second surface of the first surface, and (b) the polarizer and the first cellulose acetate. A step of bonding the film and the second cellulose acetate laminated film through the radiation curable adhesive composition; and (c) the radiation curable adhesive composition by irradiation with radiation. And a step of forming a radiation curable adhesive layer, and at least the second cellulose acetate laminated film is preferably a production method of a mode in which saponification treatment is not performed. There.

[Liquid Crystal Display]
The cellulose acetate film of the present invention and the polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Nyst) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.

  The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. The bend alignment mode liquid crystal display device has an advantage of high response speed.

  In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.

  The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625 (in Japanese Patent Publication No. 176625), and (2) a liquid crystal cell (SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (for MVA mode) in order to enlarge the viewing angle. ), (3) a liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Sharp Technical Report No. 80, page 11); (4) A SURVAVAL mode liquid crystal cell (Monthly Display May 14th page (1999)) is included.

  The VA mode liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates. In one aspect of the transmission type liquid crystal display device of the present invention, the film of the present invention is disposed between the liquid crystal cell and one polarizing plate, or between the liquid crystal cell and both polarizing plates. Arrange two.

  In another aspect of the transmissive liquid crystal display device according to the present invention, an optical compensation sheet made of the film of the present invention is used as a transparent protective film for a polarizing plate disposed between a liquid crystal cell and a polarizer. The above optical compensation sheet may be used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, or two (between the liquid crystal cell and the polarizer) of both polarizing plates. You may use said optical compensation sheet for a sheet of protective film. When the optical compensation sheet is used for only one polarizing plate, it is particularly preferable to use it as a protective film for the liquid crystal cell side of the backlight side polarizing plate of the liquid crystal cell. For the lamination to the liquid crystal cell, the film of the present invention is preferably on the VA cell side. The protective film may be a normal cellulose acetate film, and is preferably thinner than the film of the present invention. For example, it is preferably 40 to 80 μm, and examples thereof include, but are not limited to, commercially available KC4UY (40 μm manufactured by Konica Minolta Opto), KC5UX (60 μm manufactured by Konica Minolta Opto), TD80 (80 μm manufactured by Fujifilm), and the like.

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

<Preparation of Cellulose Acetate Multilayer Film 101>
<Fine particle dispersion 1>
Fine particles (Aerosil R812V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Amine-based dispersant 6 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

  The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose esters A and B were added to a pressurized dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of dope solution for core layer>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acetate A 100 parts by mass Polycondensation compound A-3 4.0 parts by mass Compound C-7 having negative intrinsic birefringence (see Table 5) 6.0 parts by mass General formula ( Compound A-4 represented by A) (see Table 4) 6.0 parts by mass <Composition of dope solution for skin B layer>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acetate D 100 parts by mass Polycondensation compound A-3 4.0 parts by mass Compound A-4 represented by formula (A) (see Table 4) 6.0 parts by mass Fine particles Additive liquid 1 part by mass <Composition of dope liquid for skin A layer>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acetate A 100 parts by mass Compound 24-2 (see [Chemical Formula 6]) 5.0 parts by mass Compound C-7 having negative intrinsic birefringence (see Table 5) 2.0 Parts by mass polycondensation compound A-3 4.0 parts by mass UV absorber: product name TINUVIN 928 manufactured by BASF Japan Ltd.
Amine-based dispersant: Solspers 20000 (manufactured by Lubrizol)
Each of the above materials was put into a sealed container and dissolved while stirring to prepare each dope solution. Next, using the co-casting die shown in FIG. 1, a three-layer cellulose acetate laminated film (simply referred to as “cellulose” using a core layer dope, a skin A layer dope, and a skin B layer dope by a co-casting method. Acele film "or" laminated film ") 101 was produced.

  Each dope was cast at a temperature of 35 ° C. on a stainless steel support.

  After casting, an endless belt casting apparatus was used to uniformly cast the dope solution on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film became 75%, and then peeled off from the stainless steel belt support with a peeling tension of 150 N / m.

  The peeled cellulose acetate film was stretched 36% in the width direction using a tenter while applying heat at 150 ° C. The residual solvent at the start of stretching was 10%.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

  As described above, a cellulose acetate laminated film 101 having a dry film thickness of 60 μm was obtained.

  Hereinafter, cellulose acetate laminated films 102 to 130 were produced in substantially the same manner except that various additive types, solvent types, and film thicknesses were changed as shown in Tables 5 to 9.

  In addition, the Nz coefficient described in Table 9 was calculated by the above formula (3) based on Rth and Re measured under the above-described method and conditions.

<Preparation of hard coat film 1>
A hard coat layer coating solution is prepared by filtering the following hard coat layer coating composition on a polypropylene filter having a pore size of 0.4 μm on the core layer of the laminated cellulose acetate film 109 prepared above, and using a micro gravure coater. applying Te, after drying at 80 ° C., using an ultraviolet lamp, irradiance 80 mW / cm ² irradiation unit to cure the coating layer the amount of irradiation as 80 mJ / cm ^2, the hard coat layer of the dry film thickness of 9 .mu.m 1 Was formed, wound up, and a roll-shaped hard coat film 1 was produced.

<Hardcoat layer coating composition>
The following materials were stirred and mixed to obtain a hard coat layer coating composition.

Thermoplastic resin, polyester urethane resin (manufactured by Toyobo Co., Ltd., trade name “Byron UR1350”, solid content concentration 33% (toluene / methyl ethyl ketone solvent = 65/35))
6.0 parts by mass (2.0 parts by mass for polyester urethane resin)
Pentaerythritol triacrylate 30 parts by mass Pentaerythritol tetraacrylate 30 parts by mass Irgacure 184 (manufactured by BASF Japan, photopolymerization initiator) 3.0 parts by mass Irgacure 907 (manufactured by BASF Japan, photopolymerization initiator) 1.0 part by mass Polyether-modified polydimethylsiloxane (BYK-UV3510, manufactured by Big Chemie Japan Co., Ltd.) 2.0 parts by mass Propylene glycol monomethyl ether 150 parts by mass Methyl ethyl ketone 150 parts by mass Production of polarizing plate, panel production, evaluation of liquid crystal display device <Production of polarizing plate 201 >
A polarizing plate 201 was produced using one each of the hard coat film 1 and the cellulose acetate laminated film 101 as a protective film for the polarizing plate.

(A) Production of Polarizing Film What was impregnated with 10 parts by mass of glycerin and 170 parts by mass of water in 100 parts by mass of polyvinyl alcohol (hereinafter abbreviated as PVA) having a saponification degree of 99.95 mol% and a polymerization degree of 2400. After melt-kneading and defoaming, it was melt-extruded from a T-die onto a metal roll to form a film. Then, it dried and heat-processed and obtained the PVA film.

  The obtained PVA film had an average thickness of 25 μm, a moisture content of 4.4%, and a film width of 3 m. Next, the obtained PVA film was continuously treated in the order of pre-swelling, dyeing, uniaxial stretching by a wet method, fixing treatment, drying, and heat treatment to produce a polarizing film. That is, the PVA film was preliminarily swollen in water at a temperature of 30 ° C. for 30 seconds, and immersed in an aqueous solution having an iodine concentration of 0.4 g / liter and a potassium iodide concentration of 40 g / liter at a temperature of 35 ° C. for 3 minutes. Subsequently, the film was uniaxially stretched 6 times in a 50% aqueous solution with a boric acid concentration of 4% under the condition that the tension applied to the film was 700 N / m, and the potassium iodide concentration was 40 g / liter and the boric acid concentration was 40 g / liter. Then, it was immersed in an aqueous solution having a zinc chloride concentration of 10 g / liter and a temperature of 30 ° C. for 5 minutes for fixing. Thereafter, the PVA film was taken out, dried with hot air at a temperature of 40 ° C., and further heat-treated at a temperature of 100 ° C. for 5 minutes. The obtained polarizing film had an average thickness of 13 μm, a polarizing performance of a transmittance of 43.0%, a polarization degree of 99.5%, and a dichroic ratio of 40.1.

(B) Production of Polarizing Plate A polarizing plate 201 was produced by bonding the polarizing film, the cellulose acetate film 101 and the hard coat film 1 according to the following steps 1 to 4.
Process 1: The above-mentioned polarizing film was immersed for 1 to 2 seconds in the storage tank of the polyvinyl alcohol adhesive agent solution of 2 mass% of solid content.
Step 2: Excess adhesion of the hard coat film 1 in which a peelable protective film (made of PET) is pasted on the cellulose acetate film 101 and the hard coat layer to the polarizing film immersed in the polyvinyl alcohol adhesive solution in Step 1 The agent was lightly removed, and the cellulose acetate film 101 and the hard coat film 1 were sandwiched between the polarizing films and laminated.
Step 3: The laminate was bonded at a speed of about 2 m / min at a pressure of ^{20 to} 30 N / cm ² with two rotating rollers. At this time, it was carried out with care to prevent bubbles from entering.
Step 4: The sample prepared in Step 3 was dried in a dryer at a temperature of 80 ° C. for 5 minutes to prepare a polarizing plate.
Step 5: A commercially available acrylic pressure-sensitive adhesive is applied to the cellulose acetate laminated film 101 of the polarizing plate prepared in Step 4 so that the thickness after drying is 25 μm, and dried in an oven at 110 ° C. for 5 minutes to form an adhesive layer. And a peelable protective film was attached to the adhesive layer. This polarizing plate was cut (punched) into a size of 960 × 600 mm to produce a polarizing plate 201.

<Production of Polarizing Plates 202 to 228>
Polarizers 202 to 228 were produced in the same manner except that the cellulose acetate laminate film 101 was changed to the cellulose acetate laminate films 102 to 108 and 111 to 130 in the production of the polarizer 201.

<Preparation of Polarizing Plate 229>
Preparation of adhesive (a) Preparation of UV adhesive (1) Preparation of UV adhesive 1 12 parts “Aronix M-315” manufactured by Toagosei Co., Ltd. 32.5 parts “Celoxide 2021P” manufactured by Daicel Chemical Industries, Ltd. Kuraray Co., Ltd. “Kuraray Polyol C-2090” 10 parts, San Apro Co., Ltd. “CPI-110A” 2.5 parts, Sakamoto Pharmaceutical Co., Ltd. “SR-NPG” 33 parts, Sanyo Chemical Industries Co., Ltd. “Sun” 8 parts of Knicks GP-400 and 2 parts of “Irgacure 184” manufactured by BASF Japan were mixed to prepare UV adhesive 1.

(2) Preparation of UV Adhesive 2 58.8 parts of 4-hydroxybutyl acrylate, 19.6 parts of vinyl ester resin (bisphenol vinyl ester), bis ((meth) acryloyloxymethyl) tricyclo [5.2.1. ^02,6 ] decane 19.6 parts, 2,4,6-trimethylbenzoyldiphenylphosphine oxide 1.1 parts, Nippon Kayaku Co., Ltd. "KAYAMER PM-2" 0.1 parts, 2-mercaptobenzothiazole 0.5 parts and 0.3 part of “Sumitizer GA80” manufactured by Sumitomo Chemical Co., Ltd. were mixed to prepare UV adhesive 2.

Bonding method (a) UV adhesive UV adhesive 1 or 2 is coated on the cellulose acetate laminated film 101 using a wire bar coater # 3, and a defect such as air bubbles enters the PVA film produced thereon. Bonded so that there was no. Next, the UV adhesive 1 or 2 was applied on the hard coat film 1 using a wire bar coater # 3, and was bonded on the PVA of the bonded film so that no defects such as bubbles would enter. . The four sides of the cellulose acetate film are fixed with tape so that the hard coat film 1 is on the glass plate, and the cellulose acetate laminated film 101 is coated with a metal halide lamp (illuminance 220 mW / cm ² , irradiation light quantity 1,000 mJ / cm ² ). Light was irradiated from the side, and the mixture was allowed to stand at 23 ° C. and 50% RH for 24 hours.

  Thereafter, a commercially available acrylic pressure-sensitive adhesive was applied to the cellulose acetate laminated film 101 side of the produced polarizing plate so that the thickness after drying was 25 μm, and dried in an oven at 110 ° C. for 5 minutes to form an adhesive layer. A peelable protective film was attached to the adhesive layer.

  In this way, a polarizing plate 229 was produced.

<Production of Polarizing Plates 230 to 235>
Polarizers 230 to 235 were produced in the same manner except that the cellulose acetate laminate film 101 was changed to the cellulose acetate laminate films 103, 113, 117, 121, 127, and 130, respectively.

<Production of Liquid Crystal Display Device 401>
The polarizing plate of the liquid crystal panel of the 40-inch display KDL-40V5 made by SONY is peeled off, and the prepared polarizing plate 201 is used as the viewing side polarizing plate so that the hard coat layer is on the viewing side. Was pasted. Further, on the backlight side, a polarizing plate 236 which is laminated and bonded so as to sandwich the polarizing film with the laminated cellulose acetate film 110 in the same manner as in the above procedure is liquid crystal using an acrylic adhesive having a thickness of 25 μm. The liquid crystal panel 301 was produced by bonding to cell glass. Next, the liquid crystal panel 301 was set on a liquid crystal television, and a liquid crystal display device 401 was manufactured.

<Production of Liquid Crystal Display Devices 402 to 428>
In the production of the liquid crystal display device 401, except that the polarizing plate 201 is changed to the polarizing plates 202 to 235, respectively, the adhesive layer and the liquid crystal cell glass are bonded so that the hard coat layer is on the viewing side. did. Moreover, on the backlight side, the polarizing plate 236 laminated and bonded so as to sandwich the polarizing film with the laminated cellulose acetate film 110 in the same manner as in the above procedure was changed to polarizing plates 237 to 270, respectively. Similarly, it bonded to liquid crystal cell glass using the acrylic adhesive with a thickness of 25 micrometers, and produced the liquid crystal panels 302-335. Next, the liquid crystal panels 302 to 335 were set on a liquid crystal television, and liquid crystal display devices 402 to 435 were manufactured.

[Evaluation]
Hereinafter, various properties of the laminated cellulose acetate film were measured and measured by the following methods.

(Hygroscopic expansion coefficient)
The hygroscopic expansion coefficient (cm / cm ·% RH) is represented by the following formula. In the following, L4 is the length (mm) of the film sample when it is changed to a relative humidity (RH4) of 23 ° C., L0 is the original size (mm) of the film sample in the standard state (23 ° C., 55% RH), RH0 is the standard relative humidity (% RH), and RH4 is the changed relative humidity (% RH).

β = {(L4-L0) / L0} / (RH4-RH0)
The hygroscopic expansion coefficient is a change in dimensions per 1% of relative humidity, and indicates whether the film has a large change or a small film due to a change in humidity. In the present invention, the hygroscopic expansion coefficient is preferably 8 × 10 ⁻⁵ (cm / cm ·% RH) or less, more preferably 6 × 10 ⁻⁵ (cm / cm ·% RH) or less. It is more preferable that it is not more than × 10 ⁻⁵ (cm / cm ·% RH).

(Moist heat dimensional stability)
A cross-shaped mark is attached to two locations (MD direction and long direction) on the surface of the cellulose ester film sample, heat treatment (conditions: 80 ° C., 90% RH, 200 hours) is performed, and the distance between the marks using a factory microscope Was measured. The dimensional change rate was calculated by the following formula, assuming that the distance before the heat treatment is a1 and the distance after the heat treatment is a2.
Dimensional change rate (%) = (a1-a2) / a1 × 100
(Peelability)
5: Peelability was very good, and no optical unevenness was visible on the film after peeling.
4: Peelability was good and optical unevenness was slightly visible on the film after peeling.
3: Separation was possible, and after peeling, there was no streak-like film thickness unevenness, but optical unevenness was visible.
2: The peelability was poor, and stripe-like film thickness unevenness was visible on the film after peeling.
1: The peelability was very poor, and the film was partially stretched during peeling.

(Internal haze)
First, the internal haze referred to in the present invention is a haze generated by a scattering factor inside the film, and the inside is a portion of 5 μm or more from the film surface.

  The internal haze is measured with a haze meter by dropping a solvent having a refractive index of film refractive index ± 0.05 on the film interface so that the haze on the film surface can be ignored as much as possible.

<Measurement of haze inside film (hereinafter abbreviated as internal haze)>
Haze meter (turbidity meter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.)
The light source uses a 5V9W halogen bulb, and the light receiving unit uses a silicon photocell (with a relative visibility filter).

  In the present invention, in the haze measurement of the film when a solvent having a refractive index of ± 0.05 is dropped on the film interface with this apparatus, the value is preferably 0.02 or less. The measurement was performed according to JIS K-7136.

  The internal haze measurement is performed as follows. A description will be given with reference to FIGS.

  First, the blank haze 1 of a measuring instrument other than a film is measured.

  1. Drip a drop (0.05 ml) of glycerin on a cleaned glass slide. At this time, care is taken so that bubbles do not enter the droplet. Glass must be washed with a detergent (see Fig. 2).

  2. Place the cover glass on top of it. Glycerin spreads without pressing the cover glass.

  3. Set on a haze meter and measure blank haze 1.

  Next, the haze 2 including the sample is measured.

  4). Glycerin (0.05 ml) is dropped onto the slide glass (see FIG. 2 (a)).

  5. A sample film to be measured is placed thereon (see FIG. 2B).

  6). Glycerin (0.05 ml) is dropped on the sample film (see FIG. 2C).

  7). A cover glass is placed thereon (see FIG. 2D).

  8). Set in a haze meter and measure haze 2.

  9. (Haze 2) − (Haze 1) = (Internal haze) is calculated.

  The glass and glycerin used in the above measurement are as follows.

Glass: MICRO SLIDE GLASS S9213 MATUNAMI
Glycerin: Kanto Kagaku Deer Special Grade "Evaluation"
The following evaluation was performed about the polarizing plates 201-270 and the image display apparatuses 401-435.

(Polarizer)
a. Observation of deformation failure The polarizing plate subjected to the above durability test was observed from the hard coat layer side, and the state of deformation failure was observed according to the following criteria.

A: Deformation failure is not observed at all. O: Deformation failure is observed in a small part, but there is no problem in actuality. Δ: Deformation failure is partially observed. There is a problem in terms of actual damage ×: It can be seen that partial deformation failure is clearly seen even from a distance.

(Liquid crystal display device)
a << Evaluation of streaks >>
Each of the produced liquid crystal display devices 401 to 435 was treated for 300 hours at 60 ° C. in order to see deterioration due to heat, and then returned to 23 ° C. and 55% RH. Then, after turning on the power and turning on the backlight, the streak (streaks) at the time of black display 2 hours later was visually evaluated according to the following criteria.
◎: No streak ○: A weak streak exists in the center △: A weak streak exists from the center to the end ×: A strong streak exists in the entire surface .

b << Evaluation of visibility >>
About each produced said liquid crystal display device, after leaving for 100 hours on 60 degreeC and 90% RH conditions, it returned to 23 degreeC and 55% RH. Thereafter, the surface of the display device was visually observed and evaluated according to the following criteria.
A: No wavy unevenness is observed on the surface. O: A slight wavy unevenness is observed on the surface. Δ: A slight wavy unevenness is slightly observed on the surface. The above evaluation results are shown in Tables 10 to 13 below.

  As can be seen from the results shown in Tables 10 to 13, the laminated cellulose acetate film of the present invention has excellent performance in terms of hygroscopic expansion coefficient, wet heat dimensional stability, and peelability.

  Moreover, as can be seen from the results shown in Tables 10 to 13, the polarizing plate produced from the laminated cellulose acetate film of the present invention has no deformation failure when stored under high temperature and high humidity, and is bonded to a polarizer. Excellent in properties. In addition, when the polarizing plate is used in a liquid crystal display device, it exhibits excellent performance in both streaking and visibility (clearness).

DESCRIPTION OF SYMBOLS 10 Co-casting die 11 Base part 13, 15 Surface layer slit 14 Base layer slit 16 Metal support 17, 19 Surface layer dope 18 Base layer dope 20 Multilayer web

Claims (10)

A skin B layer containing cellulose acetate satisfying the following formula (1), a core layer containing cellulose acetate satisfying the following formula (2), and a skin A layer containing cellulose acetate satisfying the following formula (2) A cellulose acetate laminated film formed by lamination, wherein the core layer contains a compound having negative intrinsic birefringence.
Formula (1): 2.7 <Z ₁ <3.0
(In the formula (1), Z ₁ represents the total degree of acetyl group substitution of the cellulose acetate of the skin layer B.)
Formula (2): 2.0 <Z ₂ <2.7
(In the formula (2), Z ₂ represents the total degree of acetyl group substitution of the cellulose acetate of the core layer and skin layer A.)   (A) a dicarboxylic acid residue having an average carbon number of 5.5 to 10.0 including an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue; and (b) an average carbon number of 2. The cellulose acetate laminated film according to claim 1, comprising a polycondensed ester containing an aliphatic diol residue in the range of 5 to 7.0.   The cellulose acetate laminated film according to claim 1 or 2, wherein a polymer having a cyclic structure in a side chain is contained in at least one of the skin A layer and the skin B layer.   The cellulose acetate laminated film according to any one of claims 1 to 3, wherein at least one of the skin A layer and the skin B layer contains metal fine particles and an amine-based dispersant.   The average layer thickness of the core layer is in the range of 30 to 100 μm, and the average layer thickness of at least one of the skin A layer and the skin B layer is in the range of 0.2 to 25% of the average layer thickness of the core layer. The cellulose acetate laminated film according to any one of claims 1 to 4, wherein the cellulose acetate laminated film is.   The film width is in the range of 700 to 3000 mm, and the cellulose acetate laminated film according to any one of claims 1 to 5 characterized by the above-mentioned. The core layer contains a compound represented by the following general formula (A) having a total average substitution degree in the range of 4.5 to 6.9. The cellulose acetate laminated film according to any one of the above.

(Wherein R _{1 to} R ₈ each independently represents a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ may be the same) , May be different.) The Nz coefficient represented by following formula (3) is 7 or less, The cellulose acetate laminated film as described in any one of Claim 1- Claim 7 characterized by the above-mentioned.
Formula (3): Nz coefficient = Rth / Re + 0.5   A polarizing plate comprising the cellulose acetate laminated film according to any one of claims 1 to 8.   A liquid crystal display device comprising the cellulose acetate laminated film according to any one of claims 1 to 8.

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