JP2007197508A - Cellulose derivative film and optical film and image display device using the film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose derivative film which is suitably used for an optical film, excellently exhibits retardation, is least liable to change in retardation due to moisture. <P>SOLUTION: The film contains a cellulose derivative satisfying following formulas (1)-(3). Formula (1): 2≤A+B≤3. Formula (2): 0.05≤A≤2.0. Formula (3): 0.05≤B≤2.95. (In the formulas, A is a degree of substitution of a group expressed by (Ar)<SB>3</SB>C- to the hydrogen atoms constituting the hydroxyl groups of the cellulose; Ar is a 6-20C aromatic group; B is a degree of substitution of a 2-6C alkanoyl group to the hydrogen atoms constituting the hydroxyl groups of the cellulose). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cellulose derivative film that is suitable for an optical film, has little retardation change due to humidity, is transparent, and has excellent retardation development properties. Furthermore, the present invention relates to a high-quality retardation film, polarizing plate, optical compensation film, antireflection film and image display device using the cellulose derivative film.

  Cellulose acetate is used as a support for photographic light-sensitive materials because of its transparency, toughness, and optical isotropy, and is an optical film for image display devices such as liquid crystal display devices and organic EL display devices. As its use has been expanded. As an optical film for a liquid crystal display device, a polarizing plate protective film, an in-plane retardation (Re), and a thickness direction retardation (Rth) are developed to develop an STN (Super Twisted Nematic) system, etc. The liquid crystal display device is used as a retardation film.

  In recent years, VA (Vertical Alignment), OCB (Optical Compensated Bend), or IPS (In-Plane Switching) display devices have been developed that require higher Re and Rth phase differences than STN type. There is a demand for optical film materials having various retardation development properties according to the respective liquid crystal modes.

  Cellulose acetate has poor stretchability, and the retardation expression region due to stretch orientation of the polymer alone is limited. Further, since it is a relatively hydrophilic polymer, there is a characteristic that the retardation change due to humidity is relatively large.

  Therefore, as a new optical film material to meet the above requirements, a mixed ester of cellulose acetyl group and propionyl group (cellulose mixed acylate such as cellulose acetate propionate) is used, and the solution is applied onto the support. There has been proposed a cellulose derivative film produced by casting and evaporating a part of the solvent, and then peeling off from the support to form a cellulose derivative film (Patent Document 1). Also proposed is a method in which cellulose acetate butyrate and cellulose acetate propionate are used as a cellulose mixed acylate having a melting temperature lower than that of cellulose acetate, and this is melted to form an optical film (Patent Document 2). . Melt film formation does not use an organic solvent during film formation, and thus has the advantage that the steps of dissolution and drying can be omitted and the burden on the environment is less than that of solution film formation.

  Cellulose mixed acylates such as cellulose acetate propionate and cellulose acetate butyrate have the potential to solve the above-mentioned problems of cellulose acetate. Accordingly, there is a further need to provide a new polymer material for optical films capable of developing an unprecedented excellent retardation. For example, for optical compensation of IPS mode liquid crystal, an optical film having a positive Re and a small or negative Rth may be preferable. However, most conventional cellulose acylate materials have both Re and Rth positive. Therefore, it has been difficult to achieve optical characteristics in which Rth is small or negative.

On the other hand, a method of synthesizing 6-trityl cellulose by regioselectively substituting a hydrogen atom constituting the hydroxyl group at the 6-position of cellulose with a trityl group (Patent Document 3). Also disclosed is a method of synthesizing cellulose 6-trityl-2,3-bis (3,5-dimethylphenylcarbamate) using 6-tritylcellulose as a starting material (Patent Documents 4 and 5). However, cellulose 6-trityl-2,3-bis (3,5-dimethylphenylcarbamate) is only produced as a synthetic intermediate, and what about film formation of the compound and optical properties after film formation? Is also not described.
JP 2001-188128 A JP 2000-352620 A JP-A-7-70202 JP-A-6-329561 Japanese Patent Laid-Open No. 5-240848

  An object of the present invention is to provide a cellulose derivative film that can be suitably used as an optical film, has excellent retardation, and has little retardation change due to humidity. It is another object of the present invention to provide a high-quality retardation film, polarizing plate, optical compensation film, antireflection film, and image display device using the cellulose derivative film.

  As a result of diligent investigations, the present inventors have produced a cellulose derivative film that is excellent in retardation and has little retardation change due to humidity by using a cellulose (triarylmethyl) ether derivative having a specific structure. It has been found that it has an unexpected effect.

  Further, by producing a film made from the cellulose derivative, even in the case of performing melt film forming as well as solution film forming method, high-quality cellulose derivative optical film, retardation film, polarizing plate, optical compensation film The present inventors have found that an antireflection film and an image display device can be provided.

Thus, the above object of the present invention has been achieved by the present invention having the following constitution.
[Aspect 1]
A cellulose derivative film comprising a cellulose derivative characterized by satisfying the following formulas (1) to (3).
Formula (1): 2 ≦ A + B ≦ 3
Formula (2): 0.05 ≦ A ≦ 2.0
Formula (3): 0.05 ≦ B ≦ 2.95
(In the formula, A represents the degree of substitution of the group represented by (Ar) ₃ C— with respect to the hydrogen atom constituting the hydroxyl group of cellulose, Ar represents an aromatic group having 6 to 20 carbon atoms, and B represents the cellulose. This represents the degree of substitution of the alkanoyl group having 2 to 6 carbon atoms with respect to the hydrogen atoms constituting the hydroxyl group.)
[Aspect 2]
The cellulose derivative film according to aspect 1, wherein the cellulose derivative satisfies the following formulas (4) to (6).
Formula (4): 2.4 <= A + B <= 3
Formula (5): 0.05 <= A <= 1.4
Formula (6): 1.0 ≦ B ≦ 2.95

[Aspect 3]
The cellulose derivative film according to Aspect 1 or 2, wherein the group represented by (Ar) ₃ C— is a trityl group.
[Aspect 4]
The cellulose derivative film according to any one of aspects 1 to 3, wherein the alkanoyl group having 2 to 6 carbon atoms is an acetyl group, a propionyl group, or a butyryl group.
[Aspect 5]
Any one of Embodiments 1 to 4, wherein the in-plane retardation (Re) satisfies the following formula (i) and the thickness direction retardation (Rth) satisfies the following formula (ii): The cellulose derivative film according to one item.
Formula (i): 0 nm ≦ Re ≦ 300 nm
Formula (ii): −500 nm ≦ Rth ≦ 500 nm
[Aspect 6]
A cellulose derivative film obtained by stretching the cellulose derivative film according to any one of Embodiments 1 to 5 by 0.1% to 500% in at least one direction.
[Aspect 7]
Residual organic solvent amount is 0.01 mass% or less, The cellulose derivative film as described in any one of the aspects 1-6 characterized by the above-mentioned.
[Aspect 8]
A retardation film comprising the cellulose derivative film according to any one of aspects 1 to 7.

[Aspect 9]
It is a polarizing plate which consists of a polarizing film and two protective films which pinch | interpose this polarizing film, Comprising: At least one of two protective films is a cellulose derivative film or aspect as described in any one of aspect 1-7. A polarizing plate, which is the retardation film according to claim 8.
[Aspect 10]
An optical compensation film comprising an optically anisotropic layer formed by aligning a liquid crystalline compound on the cellulose derivative film according to any one of aspects 1 to 7 or the retardation film according to aspect 8. .
[Aspect 11]
An antireflection film comprising an antireflection layer on the cellulose derivative film according to any one of aspects 1 to 7 or the retardation film according to aspect 8.
[Aspect 12]
From the cellulose derivative film according to any one of aspects 1 to 7, the retardation film according to aspect 8, the polarizing plate according to aspect 9, the optical compensation film according to aspect 10, and the antireflection film according to aspect 11. An image display device using at least one selected from the group consisting of:

  The cellulose derivative film of the present invention is suitable as an optical film because it is excellent in retardation development and has little retardation change due to humidity. In addition, a retardation film, a polarizing plate, an optical compensation film, an antireflection film, and an image display device using the cellulose derivative film are all high-quality and excellent in optical properties.

  Hereinafter, the cellulose derivative film of the present invention and the production method thereof will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

<Cellulose derivative>
The cellulose derivative preferably used for the cellulose derivative film of the present invention will be described in detail.

(Basic structure)
The glucose unit which constitutes cellulose and has β-1,4 bonds has free hydroxyl groups at the 2nd, 3rd and 6th positions. The cellulose derivative is a polymer obtained by chemically modifying some or all of these hydroxyl groups. In the present invention, the degree of substitution means the total of the ratio of substitution of the hydroxyl group of cellulose for each of the 2-position, 3-position and 6-position (for example, 100% esterification is represented as substitution degree = 1). . In addition, natural cellulose raw materials contain components other than cellulose, such as polymers (hemicellulose) of constituent sugars other than glucose (for example, xylose, mannose, etc.) and lignin corresponding to the organism or purification method from which they are derived. However, in the present invention, polymers produced using cellulose raw materials containing these as raw materials are also collectively referred to as cellulose derivatives.

The cellulose derivative of the present invention has at least two kinds of substituents represented by (Ar) ₃ C— (Ar represents an aromatic group having 6 to 20 carbon atoms) and an alkanoyl group having 2 to 6 carbon atoms. In this group, the hydrogen atom constituting the hydroxyl group of cellulose is substituted.

(Substituent represented by (Ar) ₃ C—)
First, the substituent represented by (Ar) ₃ C— will be described. Here, Ar represents an aromatic group having 6 to 20 carbon atoms. Ar preferably has 6 to 18 carbon atoms, more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Here, the groups represented by Ar may be the same or may be 2 to 3 different groups.

  Ar may have a substituent, and preferred examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched, or cyclic alkyl group). , Bicycloalkyl groups and active methine groups), alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups (regardless of the position of substitution), acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, heterocyclic oxycarbonyl groups Carbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, carboxy group or a salt thereof, oxalyl group, oxamoyl group, cyano group, carboximide Yl group (Carbonimidoyl group), formyl group, hydroxy group, al Coxy group (including groups containing ethyleneoxy group or propyleneoxy group unit repeatedly), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino Group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamido group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, ammonio Group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, quaternized heterocyclic group containing nitrogen atom (for example, pyridinio group, Dazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group, N-acylsulfamoyl group, N -A sulfonyl sulfamoyl group or a salt thereof, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a silyl group and the like can be mentioned.

  Preferred examples of the group represented by Ar include a phenyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, a 2-methoxyphenyl group, a 3-methoxyphenyl group, and a 4-methoxyphenyl group. 2,3-dimethylphenyl group, 2,4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group, 2,3-dimethoxyphenyl group, 2,4-dimethoxyphenyl group, 2 , 5-dimethoxyphenyl group, 2,6-dimethoxyphenyl group, 4-ethylphenyl group, 2-ethylphenyl group, 4-isopropylphenyl group, 3-isopropylphenyl group, 4-t-butylphenyl group, 2-chlorophenyl Group, 3-chlorophenyl group, 4-chlorophenyl group, 2,4-dichlorophenyl group, 2-bromophenyl group, 4- Lomophenyl group, 2-fluorophenyl group, 4-fluorophenyl group, 4-cyanophenyl group, 4-iodophenyl group, 2,4,5-trimethoxyphenyl group, 3,4,5-trimethoxyphenyl group, 4 -Phenoxyphenyl group, 1-naphthyl group, 2-naphthyl group and the like.

  More preferably, a phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-methoxyphenyl group, 3-methoxyphenyl group, 4-methoxyphenyl group, 2,3-dimethylphenyl group 2,4-dimethylphenyl group, 2,3-dimethoxyphenyl group, 2,4-dimethoxyphenyl group, 2,5-dimethoxyphenyl group, 2,6-dimethoxyphenyl group, 4-ethylphenyl group, 2-ethyl A phenyl group, a 4-isopropylphenyl group, a 3-isopropylphenyl group, a 4-t-butylphenyl group, and the like, and particularly preferably a phenyl group, a 2-methylphenyl group, a 3-methylphenyl group, and a 4-methylphenyl group. 2-methoxyphenyl group, 3-methoxyphenyl group, 4-methoxyphenyl group and the like.

In the present invention, the group represented by (Ar) ₃ C— is preferably a trityl group, a diphenyl (4-methoxyphenyl) methyl group, a di (4-methoxyphenyl) phenylmethyl group, or a tri (4-methoxyphenyl) methyl. Group, diphenyl (4-methylphenyl) methyl group, di (4-methylphenyl) phenylmethyl group, tri (4-methylphenyl) methyl group, tri (4-chlorophenyl) methyl group, tri (4-cyanophenylmethyl) Group, tri (4-isopropylphenyl) methyl group and the like, more preferably trityl group, diphenyl (4-methoxyphenyl) methyl group, di (4-methoxyphenyl) phenylmethyl group, tri (4 -Methoxyphenyl) methyl group, diphenyl (4-methylphenyl) methyl group, di (4-methyl) Phenyl) phenylmethyl group, a tri (4-methylphenyl) methyl group, particularly preferably a trityl group, a tri (4-methoxyphenyl) methyl group, a tri (4-methylphenyl) methyl group and the like.

In the present invention, the group represented by (Ar) ₃ C— may be substituted at any position in the 2, 3, and 6 positions of the repeating unit of cellulose at an arbitrary ratio. It is preferable to introduce them selectively. Since only the 6-position of the hydroxyl group of the repeating unit of cellulose is a primary hydroxyl group, a method of selectively introducing it into the 6-position includes a method of etherifying cellulose by reacting with trityl chloride in the presence of a base. It can be illustrated.

(C2-C6 alkanoyl group)
Next, an alkanoyl group having 2 to 6 carbon atoms will be described.
The alkanoyl group in the present invention preferably has 2 to 5 carbon atoms, more preferably 2 to 4 carbon atoms, and particularly preferably 3 to 4 carbon atoms. When the number of carbon atoms is less than 2, it may not be preferable in terms of the suitability for production and stability of the compound. In addition, when the number of carbon atoms is 7 or more, the production suitability is lowered, and the glass transition temperature of the polymer may not be appropriate when used as a film.
Examples of preferred alkanoyl groups include acetyl, propionyl, butyryl, pentanoyl, heptanoyl, hexanoyl, isobutyryl, and pivaloyl groups. More preferred are an acetyl group, a propionyl group and a butyryl group, and particularly preferred are a propionyl group and a butyryl group.

In the present invention, the alkanoyl group having 2 to 6 carbon atoms may be substituted at any position of the 2, 3 and 6 positions of the repeating unit of cellulose in any ratio, but generally 2 or 3 It is preferable to introduce them selectively. As a method of selectively introducing into the 2- or 3-position, after selectively introducing the group represented by (Ar) ₃ C— into the 6-position of the hydroxyl group of cellulose, the hydroxyl group at the 2- or 3-position is acid halide or acid. A method of reacting with an anhydride or ketene can be exemplified.

The cellulose derivative of the present invention is characterized by satisfying the substitution degree of the following formulas (1) to (3).
Formula (1): 2 ≦ A + B ≦ 3
Formula (2): 0.05 ≦ A ≦ 2.0
Formula (3): 0.05 ≦ B ≦ 2.95
(In the formula, A represents the degree of substitution of the group represented by (Ar) ₃ C— with respect to the hydrogen atom constituting the hydroxyl group of cellulose, Ar represents an aromatic group having 6 to 20 carbon atoms, and B represents the cellulose. This represents the degree of substitution of the alkanoyl group having 2 to 6 carbon atoms with respect to the hydrogen atoms constituting the hydroxyl group.)

The cellulose derivative of the present invention preferably satisfies the following formulas (4) to (6).
Formula (4): 2.4 <= A + B <= 3
Formula (5): 0.05 <= A <= 1.4
Formula (6): 1.0 ≦ B ≦ 2.95

The cellulose derivative of the present invention more preferably satisfies the following formulas (7) to (9).
Formula (7): 2.6 <= A + B <= 3
Formula (8): 0.5 <= A <= 1.3
Formula (9): 1.3 ≦ B ≦ 2.5

The cellulose derivative of the present invention particularly preferably satisfies the following formulas (10) to (12).
Formula (11): 2.7 ≦ A + B ≦ 3
Formula (12): 0.6 ≦ A ≦ 1.2
Formula (13): 1.5 <= B <= 2.4

  Preferred examples of the cellulose derivative of the present invention include 6-trityl-2,3-diacetylcellulose, 6-trityl-2,3-dipropionylcellulose, 6-trityl-2,3-dibutyrylcellulose, 6-take (4 -Methoxyphenyl) methyl-2,3-diacetylcellulose, 6- (4-methoxyphenyl) methyl-2,3-dipropionylcellulose, 6- (4-methoxyphenyl) methyl-2,3-dibutyrylcellulose 6-tri (4-methylphenyl) methyl-2,3-diacetylcellulose, 6-tri (4-methylphenyl) methyl-2,3-dipropionylcellulose, 6-tri (4-methylphenyl) methyl-2 , 3-dibutyryl cellulose. More preferred are 6-trityl-2,3-diacetylcellulose, 6-trityl-2,3-dipropionylcellulose, 6-trityl-2,3-dibutyrylcellulose, and particularly preferred is 6-trityl-2. , 3-dipropionylcellulose, 6-trityl-2,3-dibutyrylcellulose.

  In the cellulose derivative, the chemical name is generally treated as a generic term that allows some variation in the structure, such as the degree of substitution and the hydroxyl group content. For example, triacetyl cellulose is a generic name for derivatives having a degree of substitution of about 2.7-3, and ethyl cellulose is a degree of substitution of about 1.5-3. Also in the present invention, the names of the above preferred examples are generic names that allow derivatives having a variation range in the degree of substitution and the hydroxyl group content without departing from the spirit of the present invention. For example, the trityl substitution degree at the 2,3,6 position is 0.02, 0.01, 0.89, respectively, and the propionyl substitution degree at the 2,3,6 position is 0.95, 0.95, 0, respectively. The .04 cellulose derivatives are also collectively referred to as 6-trityl-2,3-dipropionylcellulose.

<Method for producing cellulose derivative>
For general synthesis methods of the cellulose derivative of the present invention, JP-A-6-329561, JP-A-5-240848, Macromol. Chem. Phys., 1996, 197, 953-964, Macromol. Chem. Phys., 2002, 203, 961-967, Org. Biomol. Chem., 2004, 2, 402-407, etc. are also described in detail, and may be applied as appropriate in the present invention. Can do.
The substituents in the present invention may be introduced into the cellulose in any order and number of steps, but the 6-position hydroxyl group can be selectively etherified, and then the 2- and 3-position hydroxyl groups can be selectively acylated (esterified). preferable.

(Raw material and pretreatment)
As the cellulose raw material, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. As a cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92 mass% to 99.9 mass%.
When the cellulose raw material is in the form of a sheet or a lump, it is preferably pulverized in advance, and it is preferable that the pulverization proceeds until the cellulose is in the form of cotton, feathers or powder.

(Activation process)
In the present invention, the cellulose raw material is preferably subjected to a pretreatment (activation) for contacting with an activator prior to etherification. It is preferable to use water as the activator. The addition method can be selected from any method such as spraying, dripping and dipping, and the activation may be performed at any temperature.

  The addition amount of the activator is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 30% by mass or more based on cellulose. It is preferable that the amount of the activator is equal to or more than the lower limit value because problems such as a decrease in the degree of activation of cellulose do not occur. The upper limit of the addition amount of the activator is not particularly limited as long as productivity is not lowered, but is preferably 10000 times or less, more preferably 5000 times or less, and 1000 times or less by mass with respect to cellulose. It is particularly preferred that Activation may be carried out by adding a large excess of activator to cellulose, and then the amount of the activator may be reduced by performing operations such as filtration, air drying, heat drying, distillation under reduced pressure, and solvent substitution.

  In the present invention, the activation temperature is preferably 20 ° C to 100 ° C. Preferably it is 25 degreeC-100 degreeC, More preferably, it is 40 degreeC-100 degreeC, Most preferably, it is 40 degreeC-80 degreeC. The step of activating cellulose can also be performed under pressure or reduced pressure. Moreover, you may use electromagnetic waves, such as a microwave and infrared rays, as a heating means. The activation time is preferably 5 minutes or more, more preferably 1 hour or more, and particularly preferably 1.5 hours or more. The upper limit is not particularly limited as long as it does not affect the productivity, but is preferably 72 hours or less, more preferably 24 hours or less, and particularly preferably 12 hours or less.

(Dehydration treatment)
In the present invention, dehydration is preferably performed prior to etherification. In dehydration, it is preferable not to reduce the above-mentioned activation effect, and it is possible to remove moisture in cellulose by immersing cellulose in a polar organic solvent and repeating dehydration and immersion in a polar organic solvent. Preferably done. It is preferable to adjust the dehydration conditions (temperature, number of repetitions, etc.) depending on the presence or absence of activation or the content of activator.
As the polar organic solvent, any solvent can be selected as long as it is mixed with an activator such as water and does not inhibit the etherification described below. Preferable examples of the polar organic solvent include dimethylformamide, dimethylacetamide, N-methylpyrrolidone, acetonitrile, dimethylsulfoxide, pyridine and the like, and more preferable are dimethylformamide, dimethylacetamide, N-methylpyrrolidone and pyridine. Particularly preferred are dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.
The temperature of the dehydration treatment is preferably 20 ° C to 220 ° C. More preferably, it is 30 degreeC-190 degreeC, More preferably, it is 40 degreeC-185 degreeC, Most preferably, it is 60 degreeC-180 degreeC.
The water content in the dehydrated cellulose and the organic solvent is preferably 6% or less, more preferably 4% or less, and particularly preferably 3% or less.

(Dissolution)
In the present invention, it is also preferable to dissolve cellulose prior to etherification. Dissolution can be carried out by any method, but the cellulose is stirred with an organic solvent (preferably dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.) together with a salt such as lithium chloride, lithium bromide or lithium fluoride. Thus, a cellulose solution can be obtained. The addition amount of the salt is preferably 0.1 to 100 times by mass, more preferably 0.3 to 10 times, and particularly preferably 0.5 to 10 times that of cellulose. The amount of the organic solvent used is preferably 0.1 to 1000 times by mass, more preferably 0.5 to 100 times, and particularly preferably 1 to 30 times that of cellulose.
The temperature during dissolution is preferably 20 ° C to 220 ° C. More preferably, it is 30 degreeC-190 degreeC, More preferably, it is 40 degreeC-185 degreeC, Most preferably, it is 60 degreeC-180 degreeC.
In order to increase the solubility of cellulose, heating and cooling (preferably 0 ° C. to −100 ° C., more preferably −30 ° C. to −90 ° C., particularly preferably −50 ° C. to −90 ° C.) are repeated. Is also preferable. Furthermore, prior to the etherification described below, if undissolved cellulose is present, filtration may be performed to remove insoluble matters.

(Etherification)
Etherification may be carried out by any method, but it is preferable to react cellulose with a triarylmethyl halide (such as chloride, bromide, fluoride) as an etherifying agent in the presence of a base catalyst.
The addition amount of the etherifying agent is preferably 1 to 100 equivalents, preferably 1 to 50 equivalents, and particularly preferably 1 to 20 equivalents with respect to the hydroxyl group of cellulose.
Any base can be selected, but preferably pyridine, 2,6-lutidine, imidazole, triethylamine, diisopropylethylamine, morpholine, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, calcium carbonate, carbonate Sodium hydrogen, potassium hydrogen carbonate, sodium acetate and the like can be mentioned, more preferably pyridine, 2,6-lutidine, imidazole, triethylamine, diisopropylethylamine and the like can be mentioned, and particularly preferred are pyridine, triethylamine and diisopropyl. Examples include ethylamine. The addition amount of the etherifying agent is preferably 0 to 100 equivalents, preferably 0.5 to 50 equivalents, and particularly preferably 1 to 20 equivalents with respect to the hydroxyl group of cellulose. When a basic solvent (pyridine, dimethylformamide, dimethylacetamide, etc.) is used, etherification may be carried out without adding a base.

(Conditions for etherification)
In the present invention, the etherification can be carried out at any temperature, but is preferably 20 to 150 ° C, more preferably 30 to 120 ° C, and particularly preferably 40 to 100 ° C. The etherification time is preferably 0.1 to 1000 hours, more preferably 0.3 to 500 hours, and particularly preferably 1 to 100 hours.
It is also preferable to control the substitution degree and substitution degree distribution by adjusting the etherification temperature, time, and the concentration and amount of the etherifying agent and catalyst.

(Removal of ether body)
In the present invention, even if the ether form is once taken out and purified and then subjected to the acylation in the next step, the acylation in the next step may be continued without any particular purification.

(Esterification)
In the method for producing a cellulose derivative in the present invention, it is preferable to acylate a hydroxyl group of cellulose by adding an acid halide or acid anhydride of a carboxylic acid as an acylating agent to cellulose and reacting with a base as a catalyst. .

(Acylating agent)
The acylating agent used in the present invention is preferably a halide of an aliphatic carboxylic acid having 2 to 6 carbon atoms, more preferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbon atoms, and particularly preferably 3 to 4 carbon atoms. Or it is an acid halide.
The acid anhydride is preferably, for example, acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride, valeric anhydride, 3-methylbutyric anhydride, 2-methylbutyric anhydride, 2, 2-dimethylpropionic anhydride, hexanoic anhydride, 2-methylvaleric anhydride, 3-methylvaleric anhydride, 4-methylvaleric anhydride, 2,2-dimethylbutyric anhydride, 2,3- Examples thereof include dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, and cyclopentanecarboxylic anhydride. More preferred are acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, heptanoic anhydride and the like, and particularly preferred are acetic anhydride, propionic anhydride, butyric acid. Anhydrous.

  The acid halide is preferably, for example, acetyl chloride, acetyl bromide, propionyl chloride, propionyl bromide, butyric acid chloride, butyric acid bromide, 2-methylpropionic acid chloride, valeric acid chloride, 3-methylbutyric acid chloride, 2-methylbutyric acid chloride, 2,2-dimethylpropionic acid chloride, hexanoic acid chloride, 2-methylvaleric acid chloride, 3-methylvaleric acid chloride, 4-methylvaleric acid chloride, 2,2-dimethylbutyric acid chloride, 2,3-dimethylbutyric acid chloride, Examples include 3,3-dimethylbutyric acid chloride and cyclopentanecarboxylic acid chloride. More preferred are acetyl chloride, propionic acid chloride, butyric acid chloride, valeric acid chloride, hexanoic acid chloride, heptanoic acid chloride and the like, and particularly preferred are acetyl chloride, propionic acid chloride and butyric acid chloride.

  In the production method of the present invention, the acylating agent is preferably added in an amount of 1 to 50 equivalents relative to the hydroxyl group of cellulose, more preferably 1.1 to 30 equivalents, and 1.3 to 10 equivalents. Is particularly preferred.

  In the present invention, a cellulose mixed acylate may be obtained by using a plurality of acylating agents. As a synthesis method, an acylating agent derived from two carboxylic acids as an acylating agent is reacted by mixing or sequential addition (for example, acetyl chloride and propionyl chloride), and acylation constituted by two carboxylic acids A method using an agent (for example, acetic acid / propionic acid mixed acid anhydride), mixed acid anhydride ( For example, a method in which acetic acid / propionic acid mixed acid anhydride) is generated and reacted with cellulose, a cellulose derivative having a degree of substitution of less than 3 is once synthesized, and further, an acid anhydride or acid halide of a different carboxylic acid is used. The remaining hydroxyl group may be further acylated.

(catalyst)
The acylation catalyst used for the production of the cellulose derivative in the present invention preferably uses a base. Any base can be selected, but preferably pyridine, 2,6-lutidine, imidazole, triethylamine, diisopropylethylamine, morpholine, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, calcium carbonate, carbonate Sodium hydrogen, potassium hydrogen carbonate, sodium acetate and the like can be mentioned, more preferably pyridine, 2,6-lutidine, imidazole, triethylamine, diisopropylethylamine and the like can be mentioned, and particularly preferred are pyridine, triethylamine and diisopropyl. Examples include ethylamine. The addition amount of the etherifying agent is preferably 0 to 100 equivalents, preferably 0.5 to 50 equivalents, and particularly preferably 1 to 20 equivalents with respect to the hydroxyl group of cellulose.

(solvent)
In carrying out acylation, a solvent may be added for the purpose of adjusting viscosity, reaction rate, stirring property, acyl substitution ratio, and the like. As such a solvent, pyridine, 2,6-lutidine, dimethylformamide, dimethylacetamide, tetrahydrofuran, dioxane, N-methylpyrrolidone, dichloromethane, chloroform, acetone, ethyl methyl ketone, toluene, dimethyl sulfoxide, sulfolane, etc. should be used. You can also.
Preferred are pyridine, 2,6-lutidine, dimethylformamide, dimethylacetamide, tetrahydrofuran, dioxane, N-methylpyrrolidone, acetone, ethyl methyl ketone, dimethyl sulfoxide, sulfolane, and more preferably pyridine, dimethylformamide, dimethyl. Acetamide, tetrahydrofuran, N-methylpyrrolidone, acetone, ethylmethylketone, and the like are preferable, and pyridine, dimethylformamide, dimethylacetamide, tetrahydrofuran, N-methylpyrrolidone, acetone, and the like are particularly preferable.
The amount of the solvent can be arbitrarily selected, but the preferable addition amount is 0 to 5000% by mass, more preferably 0 to 3000% by mass, and particularly preferably 0 to 3000% by mass with respect to cellulose (mass conversion). 2000% by mass.

(Conditions for acylation)
In the present invention, acylation can be carried out at any temperature, but is preferably 20 to 150 ° C, more preferably 30 to 120 ° C, and particularly preferably 40 to 100 ° C. The etherification time is preferably 0.1 to 1000 hours, more preferably 0.3 to 500 hours, and particularly preferably 1 to 100 hours.
It is also preferable to control the substitution degree and the substitution degree distribution by adjusting the acylation temperature, time, and the concentration and amount of the acylating agent and the catalyst.

(Filtration)
The reaction mixture (dope) may be filtered for the purpose of removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in the cellulose derivative. Filtration may be performed in any step from the start of etherification to reprecipitation of the cellulose derivative of the present invention. For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.

(Reprecipitation)
The cellulose derivative solution thus obtained is mixed in a poor solvent (a solvent containing water, alcohol, etc.) or the cellulose derivative solution is mixed with the poor solvent to reprecipitate the cellulose derivative. The objective cellulose derivative can be obtained by washing. The reprecipitation may be carried out continuously or batchwise by a fixed amount. It is also preferable to control the form, apparent density, or molecular weight distribution of the re-precipitated cellulose derivative by adjusting the concentration of the cellulose derivative solution and the composition of the poor solvent according to the substitution mode or degree of polymerization of the cellulose derivative.
In addition, for the purpose of improving the purification effect, adjusting the molecular weight distribution and the apparent density, the cellulose derivative once reprecipitated is dissolved again in the good solvent (for example, acetic acid or acetone), and the poor solvent (for example, for example, The operation of reprecipitation by the action of water or an aqueous solution of carboxylic acid (acetic acid, propionic acid, butyric acid, etc.), methanol, etc. may be performed once or multiple times as necessary.

(Washing)
The produced cellulose derivative is preferably washed. The washing solvent may be any solvent as long as it has low solubility of the cellulose derivative and can remove impurities, but usually a poor solvent such as water or alcohol is used. The temperature of the cleaning liquid is preferably 15 ° C to 100 ° C, more preferably 25 ° C to 90 ° C, and particularly preferably 30 ° C to 80 ° C. The washing treatment may be performed by a so-called batch method in which filtration and replacement of the washing liquid are repeated, or may be carried out using a continuous washing apparatus. The progress of washing may be traced by any means, but preferred examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, and atomic absorption spectrum.

(Stabilization)
The cellulose derivative after washing is weakly alkaline (for example, carbonates, bicarbonates, hydroxides of sodium, potassium, calcium, magnesium, aluminum, etc.) in order to further improve the stability or reduce the carboxylic acid odor. It is also preferable to treat with an aqueous solution of an oxide.
The amount and type of the remaining stabilizer can be controlled by the amount of the cleaning liquid, the cleaning temperature, the time, the stirring method, the form of the cleaning container, the composition and concentration of the stabilizer.

(Degree of polymerization)
The degree of polymerization of the cellulose derivative used in the present invention is preferably from 80 to 1000, more preferably from 100 to 850, still more preferably from 120 to 750, and particularly preferably from 130 to 650, as a number average degree of polymerization according to the GPC method. . In addition to the molecular weight distribution measurement by gel permeation chromatography (GPC), the average degree of polymerization is Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. It can also be measured by methods such as year These are further described in detail in JP-A-9-95538.
In the present invention, the weight average degree of polymerization / number average degree of polymerization of the cellulose derivative is preferably 1.6 to 3.6, more preferably 1.7 to 3.3, and more preferably 1.8 to 3. .2 is particularly preferred.

In the present invention, the average degree of substitution of substituents can be determined by ¹ H-NMR or ¹³ C-NMR.

  In the present invention, two or more different cellulose derivatives may be mixed or separated into layers.

(Dry)
In the present invention, in order to adjust the water content of the cellulose derivative composition to a preferable amount, it is preferable to dry the cellulose derivative composition. The drying method is not particularly limited as long as the desired moisture content can be obtained. However, it is preferable that the drying method be performed efficiently by using means such as heating, air blowing, decompression, and stirring alone or in combination. The drying temperature is preferably 0 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 50 to 100 ° C. The water content of the cellulose derivative composition of the present invention is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

(Form)
Although the cellulose derivative composition of the present invention can take various shapes such as particles, powders, fibers, and lumps, it is preferable that the raw material for film production is in the form of particles or powders. The cellulose derivative composition may be pulverized or sieved to make the particle size uniform and improve the handleability. When the cellulose derivative composition is in the form of particles, 90% by mass or more of the particles to be used preferably have a particle size of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle size of 1-4 mm. The cellulose derivative composition particles preferably have a shape as close to a sphere as possible. The cellulose derivative composition of the present invention preferably has an apparent density of 0.5 to 1.3 g / cm ³ , more preferably 0.7 to 1.2 g / cm ³ , and particularly preferably 0.8 to 1.g. 15 g / cm ³ . The method for measuring the apparent density is defined in JIS K-7365.
The angle of repose of the cellulose derivative composition of the present invention is preferably 10 to 70 degrees, more preferably 15 to 60 degrees, and particularly preferably 20 to 50 degrees.

<Optical properties of cellulose derivative film>
Next, the cellulose derivative film of the present invention will be described. The cellulose derivative film of the present invention preferably satisfies the following formulas (i) and (ii).
Formula (i): 0 nm ≦ Re ≦ 300 nm
Formula (ii): −500 nm ≦ Rth ≦ 500 nm
Re is more preferably 0 nm to 250 nm, and particularly preferably 0 nm to 200 nm. Rth is more preferably −400 nm to 400 nm, and particularly preferably −300 nm to 400 nm.

  In this specification, Re and Rth are calculated based on the following. Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at wavelength λ. 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 incident on light having a wavelength of λ nm from the direction inclined by + 40 ° with respect to the normal direction of the film with Re (λ) and the slow axis (determined by KOBRA 21ADH) as the tilt axis (rotation axis). The retardation value measured in this way, and the retardation value measured by making light of wavelength λ nm incident from a direction inclined −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis KOBRA 21ADH is calculated based on the retardation value measured in (1). At this time, it is necessary to input an assumed value of average refractive index and a film thickness. KOBRA 21ADH calculates nx, ny, and nz in addition to Rth (λ). The average refractive index of 1.48 is used for cellulose acetate, but values of polymer films for typical optical applications other than cellulose acetate include cycloolefin polymer (1.52), polycarbonate (1.59), poly Values such as methyl methacrylate (1.49) and polystyrene (1.59) can be used. As the average refractive index value of other existing polymer materials, a polymer handbook (John Wiley & Sons, Inc.) or a catalog value of a polymer film can be used. In addition, in the case of a material whose average refractive index is unknown, it can be measured using an Abbe refractometer. In this specification, λ refers to 550 ± 5 nm or 590 ± 5 nm unless otherwise specified.

  Although the manufacturing method of the cellulose derivative film of this invention is not specifically limited, It is preferable to manufacture with the melt film forming method or the solution film forming method described below.

<Melting film formation>
The preferable form in the case of manufacturing the cellulose derivative film of this invention by a melt film forming method is demonstrated.

  In the present invention, only one type of cellulose derivative may be used, or two or more types may be mixed and used. Moreover, polymer components other than the cellulose derivative of the present invention and various additives can be appropriately mixed. The component to be mixed is preferably excellent in compatibility with the cellulose derivative, and the transmittance when formed into a film is preferably 80% or more, more preferably 90% or more, and particularly preferably 92% or more. Is desirable.

The melt viscosity at 220 ° C. of the cellulose derivative composition used for melt film formation (the melt viscosity at 220 ° C. of the cellulose derivative film to be produced) is preferably 100 Pa · s to 2000 Pa · s, more preferably 120 Pa · s to 1500 Pa ·. s, more preferably 150 Pa · sj to 1000 Pa · s.
In order to make melt viscosity into said preferable range, it is preferable that the number average degree of polymerization of a cellulose derivative is 70-250, More preferably, it is 90-200, Most preferably, it is 120-180. Moreover, it is preferable that a weight average polymerization degree is 150-700, More preferably, it is 200-550, Most preferably, it is 250-500.
If the degree of polymerization is too larger than the preferred range, the melt viscosity may become too high and film formation may be difficult. On the other hand, if the degree of polymerization is too smaller than the preferred range, the strength as a film will be too low, and the melt viscosity will be too low and sufficient shearing may not be applied during kneading, resulting in insufficient kneading.

(Stabilizer)
In the present invention, it is effective to add a stabilizer in order to maintain the stability of the cellulose derivative during high-temperature melt film formation. In particular, it is preferable to add at least one selected from a phenol-based stabilizer having a molecular weight of 500 or more and a phosphite-based stabilizer or a thioether-based stabilizer having a molecular weight of 500 or more. As the preferred phenol-based stabilizer, any known phenol-based stabilizer can be used. Preferable phenolic stabilizers include hindered phenolic stabilizers. In particular, it is preferable to have a substituent at a site adjacent to the phenolic hydroxyl group. In this case, the substituent is preferably a substituted or unsubstituted alkyl group having 1 to 22 carbon atoms, such as a methyl group, an ethyl group, a propionyl group, An isopropionyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, an isopentyl group, a t-pentyl group, a hexyl group, an octyl group, an isooctyl group, and a 2-ethylhexyl group are more preferable. Moreover, the stabilizer which has a phenol group and a phosphite group in the same molecule is also mentioned as a preferable material.

  These are readily available as commercial products and are sold by the following manufacturers. From Ciba Specialty Chemicals, Irganox 1076, Irganox 1010, Irganox 3113, Irganox 245, Irganox 1135, Irganox 1330, Irganox 259, Irganox 565, Irganx 565, Ir35x1025 Moreover, it can obtain from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-20, ADK STAB AO-70, and ADK STAB AO-80. Furthermore, from Sumitomo Chemical Co., Ltd., it can obtain as Sumilizer BP-76, Sumilizer BP-101, Sumilizer GA-80. In addition, it is also possible to obtain as Sinox 326M and Sinox 336B from Sipro Kasei Co., Ltd.

  It is also preferable to contain a phosphite stabilizer having a molecular weight of 500 or more that has an antioxidant effect. Examples of these compounds include the compounds described in JP-A No. 2004-182979, [0023] to [0039], JP-A No. 51-70316, JP-A No. 10-306175, JP-A No. 57-. No. 78431, JP-A-54-157159, and JP-A-55-13765. In addition, as other stabilizers, it is selected from the materials described in detail on pages 17 to 22 of the Japan Institute of Invention Information (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). Can be used. These are commercially available from Asahi Denka Kogyo Co., Ltd. as ADK STAB 1178, 2112, PEP-8, PEP-24G, PEP-36G, and HP-10, and Sandostab P-EPQ from Clariant. Is possible.

  As the thioether stabilizer, any known thioether stabilizer can be used. It is commercially available from Sumitomo Chemical Co. as Sumilizer TPL, TPM, TPS and TDP. It is also available from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-412S. When these stabilizers are used, at least one phenol-based stabilizer and at least one selected from a phosphite-based stabilizer or a thioether-based stabilizer are each contained in an amount of 0.02 to 3% by mass based on the cellulose derivative. It is preferable to contain 0.05-1 mass% especially. The ratio of the content of the phenol stabilizer and the phosphite stabilizer or thioether stabilizer is not particularly limited, but is preferably 1/10 to 10/1 (parts by mass), more preferably 1 / 5 to 5/1 (parts by mass), more preferably 1/3 to 3/1 (parts by mass), and particularly preferably 1/3 to 2/1 (parts by mass).

  In the present invention, a stabilizer having a phenol group and a phosphite group in the same molecule is also recommended. Those materials are described in JP-A-10-273494. As a commercially available product, Sumilyzer GP (Sumitomo Chemical Co., Ltd.) can be mentioned. Further, a long chain aliphatic amine described in JP-A-61-63686, a compound containing a sterically hindered amine group described in JP-A-6-329830, and a hindered dye described in JP-A-7-90270. Peridinyl light stabilizers and organic amines described in JP-A-7-278164 may also be used. Preferred amine stabilizers are ADK STAB LA-57, LA-52, LA-67, LA-62, LA-77 from Asahi Denka, and TINUVIN 765, 144 from Ciba Specialty Chemicals. It is commercially available. The use ratio of amines to phosphites is usually about 0.01 to 25% by mass.

(Plasticizer)
If a plasticizer is added to the molten cellulose derivative, the crystal melting temperature (Tm) of the cellulose derivative can be lowered. Although the molecular weight of the plasticizer used for this invention is not specifically limited, Preferably a high molecular weight plasticizer is mentioned, For example, molecular weight is preferable 500 or more, More preferably, it is 550 or more, Furthermore, 600 or more is preferable. Examples of the plasticizer include phosphate esters, alkylphthalylalkyl glycolates, carboxylic acid esters, and fatty acid esters of polyhydric alcohols. These plasticizers may be solid or oily. That is, the melting point and boiling point are not particularly limited. When performing melt film formation, those having non-volatility can be particularly preferably used.

  Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, and phenyl diphenyl phosphate.

  Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of carboxylic acid esters include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and diethylhexyl phthalate, and acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate. Citric acid esters of In addition, it is also preferable to use butyl oleate, methyl acetyl linoleate, dibutyl sebacate, triacetin or the like alone or in combination.

  The addition amount of these plasticizers is preferably 0% by mass to 15% by mass, more preferably 0% by mass to 10% by mass, and particularly preferably 0% by mass to 8% by mass of the cellulose derivative composition used for melt film formation. . These plasticizers may be used in combination of two or more as required.

(UV absorber)
An ultraviolet inhibitor may be added to the cellulose derivative composition used for melt film formation. With respect to the ultraviolet ray inhibitor, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-118233. 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, and JP-A-2000-204173. . The addition amount is preferably 0.01 to 2% by mass, more preferably 0.01 to 1.5% by mass of the melt (melt) to be prepared.

  These ultraviolet absorbers are available as the following commercial products. As benzotriazoles, TINUBIN P (Ciba Specialty Chemicals), TINUBIN 234 (Ciba Specialty Chemicals), TINUBIN 320 (Ciba Specialty Chemicals), TINUBIN 326 (Ciba Specialty Chemicals) TINUBIN 327 (Ciba Specialty Chemicals), TINUBIN 328 (Ciba Specialty Chemicals), Sumisorb 340 (Sumitomo Chemical), Adekas Type LA-31 (Asahi Denka Kogyo Co., Ltd.), etc. . In addition, as benzophenone-based ultraviolet absorbers, Seasorb 100 (manufactured by Sipro Kasei Co., Ltd.), Seasorb 101 (manufactured by Sipro Kasei Co., Ltd.), Seasorb 101S (manufactured by Sipro Kasei Co., Ltd.), Seasorb 102 (manufactured by Sipro Kasei Co., Ltd.), Seasorb 103 (Sipro Kasei) Kasei Co., Ltd.), Adekas Type LA-51 (Asahi Denka Kogyo Co., Ltd.), Chemisorp 111 (Chemipro Kasei Co., Ltd.), UVINUL D-49 (BASF Corp.), and the like. Examples of oxalic acid anilide UV absorbers include TINUBIN 312 (manufactured by Ciba Specialty Chemicals) and TINUBIN 315 (manufactured by Ciba Specialty Chemicals). In addition, as a salicylic acid ultraviolet absorber, Seasorb 201 (manufactured by Sipro Kasei) and Seasorb 202 (manufactured by Sipro Kasei) are marketed, and as a cyanoacrylate ultraviolet absorber, Seasorb 501 (manufactured by Sipro Kasei), UVINUL N-539 (BASF) is available.

(Fine particles)
In the present invention, it is also preferable to add fine particles to the cellulose derivative composition used for melt film formation.
In the present invention, the fine particles include inorganic compound fine particles or organic compound fine particles, and either one or both of them may be included. The average primary particle size of the fine particles contained in the cellulose derivative in the present invention is preferably 5 nm to 3 μm, more preferably 5 nm to 2.5 μm, and particularly preferably 20 nm to 2.0 μm. The addition amount of the fine particles is preferably 0.005 to 1.0% by mass, more preferably 0.01 to 0.8% by mass, and further 0.02 to 0.4% by mass with respect to the cellulose derivative. Particularly preferred. In the present invention, the “average primary particle size” refers to the particle size of fine particles in a dispersed state (non-aggregated state). The average primary particle size is determined by dynamic light scattering (several nm-1 μm), laser diffraction (0 0.1 μm to several thousand μm) and a laser diffraction / scattering method (several tens nm to 1 μm) based on Mie theory.

Preferred examples of the inorganic compound fine particles include SiO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ , In ₂ O ₃ , MgO, BaO, MoO ₂ , V ₂ O ₅ , talc, clay, Examples include calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Preferably, at least one of SiO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ , In ₂ O ₃ , MgO, BaO, MoO ₂ , and V ₂ O ₅ is preferable, and SiO ₂ is more preferable. , TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ .

As the fine particles of SiO ₂ , for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, manufactured by Nippon Aerosil Co., Ltd.) can be used. As the ZrO ₂ fine particles, for example, commercially available products such as Aerosil R976 and R811 (above, manufactured by Nippon Aerosil Co., Ltd.) can be used. Seahoster KE-E10, E30, E40, E50, E50, E70, E150, W10, W30, W50, P10, P30, P50, P100, P150, P250 ) Etc. are also used. Further, silica microbeads P-400 and 700 (catalyst chemical industry products) can also be used. SO-G1, SO-G2, SO-G3, SO-G4, SO-G5, SO-G6, SO-E1, SO-E2, SO-E3, SO-E4, SO-E5, SO-E6, SO- It can also be used as C1, SO-C2, SO-C3, SO-C4, SO-C5, SO-C6 (manufactured by Admatechs Co., Ltd.). Further, Moritex Corp. silica particles (aqueous dispersion powdered) 8050, 8070, 8100, 8150 can also be used.

  Preferable examples of the organic compound fine particles include polymers such as silicone resins, fluorine resins, and acrylic resins, and silicone resins are particularly preferable. The silicone resin preferably has a three-dimensional network structure, such as Tospearl 103, 105, 108, 120, 145, 3120, and 240 (above, manufactured by Toshiba Silicone Co., Ltd.). Commercial products having a trade name can be used.

Furthermore, the fine particles comprising an inorganic compound are preferably surface-treated in order to stably exist in the cellulose derivative composition and the film. The inorganic fine particles are preferably used after being subjected to a surface treatment. The surface treatment method includes chemical surface treatment using a coupling agent and physical surface treatment such as plasma discharge treatment and corona discharge treatment. In the present invention, the use of a coupling agent is preferred. As the coupling agent, an organoalkoxy metal compound (for example, a silane coupling agent, a titanium coupling agent, etc.) is preferably used. When inorganic fine particles are used as the fine particles (especially when SiO ₂ is used), treatment with a silane coupling agent is particularly effective. An organosilane compound can be used as the silane coupling agent. Although the usage-amount of the said silane coupling agent is not specifically limited, It is recommended to use 0.005-5 mass% preferably with respect to an inorganic fine particle, Furthermore, 0.01-3 mass% is preferable.
The fine particles may be mixed with the cellulose derivative in any step of film formation. Among the steps for producing the cellulose derivative, the fine particles are added in any step before reprecipitation, and are reconstituted in a state containing the fine particles. It is also preferred to precipitate.

(Release agent)
It is also preferable that the cellulose derivative composition used for melt film formation contains a compound having a fluorine atom. The compound having a fluorine atom can exhibit an action as a release agent, and may be a low molecular weight compound or a polymer. Examples of the polymer include the polymers described in JP-A No. 2001-269564. A polymer having a fluorine atom is preferably a polymer obtained by polymerizing a monomer containing an ethylated unsaturated monomer containing a fluorinated alkyl group as an essential component. The fluorinated alkyl group-containing ethylenically unsaturated monomer related to the polymer is not particularly limited as long as it is a compound having an ethylenically unsaturated group and a fluorinated alkyl group in the molecule. A surfactant having a fluorine atom can also be used, and a nonionic surfactant is particularly preferable.

(Pelletized)
The cellulose derivative and the additive are preferably mixed and pelletized prior to melt film formation.
Pelletization can be made by melting the cellulose derivative and the additive at 150 ° C. to 250 ° C. using a biaxial or uniaxial kneading extruder and then solidifying and cutting in noodles. Pelletization may be performed by an underwater cut method in which the material is cut while being extruded directly into water. More preferably, the kneading and extruding machine is a vent type and is pelletized while decompressing. Further, it is more preferable to pelletize the inside of the kneading extruder while replacing with nitrogen.
Preferably, the pellet size is such cross-sectional area is 1 mm ² to 300 mm ^2, a length 1Mm～30mm, and more preferably the cross-sectional area of 2 mm ² 100 mm ^2, length 1.5Mm～10mm.
The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 30 rpm to 500 rpm. The extrusion residence time in pelletization is 10 seconds to 30 minutes, preferably 30 seconds to 3 minutes.

(Specific method of melt film formation)
Below, the specific method of melt film forming is demonstrated.
(1) Drying Prior to melt film formation, moisture in the pellets is dried so that the moisture content is preferably 0.1% by mass or less, more preferably 0.01% by mass or less.
Drying temperature for this is preferably from 40 to 180 ° C., amount of drying air is preferably 20 to 400 m ³ / hour, and particularly preferably 100 to 250 m ³ / hour. The dew point of the drying wind is preferably 0 to -60 ° C, more preferably -20 to -40 ° C.

(2) Melt extrusion The dried cellulose derivative resin is fed into the cylinder from the feed port of the extruder.
The screw compression ratio of the extruder is preferably 2.5 to 4.5, more preferably 3.0 to 4.0. L (screw length) / D (screw diameter) is preferably 20 to 70. More preferably, it is 24-50. The melting temperature is preferably performed at the above-described temperature.
As the screw, a full flight, a mudock, a dull image, or the like can be used.
In order to prevent the oxidation of the resin, it is more preferable to carry out the inside of the extruder in an inert (nitrogen or the like) air stream or while evacuating it using a vented extruder.

(3) Filtration It is preferable to perform breaker plate type filtration at the exit of the extruder.
For high-precision filtration, it is preferable to provide a leaf type disk filter type filtration device after passing through the gear pump. Filtration may be performed in a single stage or in multiple stages. The filtration accuracy of the filter medium is preferably 3 μm to 15 μm, more preferably 3 μm to 10 μm. The filter medium is preferably stainless steel or steel, and stainless steel is particularly preferable. As the filter medium, a knitted wire or a sintered metal filter medium can be used, and the latter is particularly preferable.

(4) Gear pump It is preferable to install a gear pump between the extruder and the die in order to improve the thickness accuracy (reduction in fluctuation of the discharge amount). Thereby, the resin pressure fluctuation width of the die portion can be made within ± 1%.
In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw is also preferable. A high-precision gear pump using three or more gears is also effective. Since the staying part in the gear pump causes resin deterioration, a structure with less staying is preferable.
In order to stabilize the extrusion pressure, it is preferable to reduce the temperature fluctuation of the adapter connecting the extruder and the gear pump, and the gear pump and the die. For this purpose, it is more preferable to use an aluminum cast heater.

(5) Die As long as the molten resin stays in the die, any type of commonly used T die, fishtail die, and hanger coat die may be used. Also, there is no problem in placing a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance of the T-die outlet portion is generally 1.0 to 5.0 times the film thickness, more preferably 1.3 to 2 times.
The die clearance is preferably adjustable at intervals of 40 to 50 mm, and more preferably adjustable at intervals of 25 mm or less. A method of measuring the downstream film thickness and feeding it back to the die thickness adjustment is also effective in reducing the thickness variation.
Since the functional layer is provided on the outer layer, it is possible to produce a film having two or more kinds of structures using a multilayer film forming apparatus.
The preferred residence time of the resin from the supply port through the extruder until it exits the die is 2 minutes to 60 minutes, more preferably 4 minutes to 30 minutes.

(6) Casting The molten resin extruded from the die onto the sheet is cooled and solidified on the casting drum to obtain a film. At this time, it is also preferable to use a touch roll.
It is preferable to use 1 to 8 casting drums, more preferably 2 to 5 casting drums, and slowly cool them. The diameter of the casting roll and the touch roll is preferably 50 mm to 5000 mm, more preferably 150 mm to 1000 mm. The interval between the plurality of casting rolls is preferably 0.3 mm to 300 mm, more preferably 3 mm to 30 mm between the surfaces.
Then, it peels off from a casting drum, winds up after passing through a nip roll. The thickness of the unstretched film thus obtained is preferably 30 μm to 400 μm, more preferably 50 μm to 200 μm.

(7) Winding It is preferable to trim both ends before winding. The trimmed portion may be reused as a film raw material. As the trimming cutter, any rotary cutter, shear blade, knife, or the like may be used. Regarding the material, carbon steel, stainless steel, and ceramic can be used.
The winding tension is preferably 1 kg / m width to 50 kg / width, more preferably 3 kg / m width to 20 kg / m width. The take-up tension may be taken up with a constant take-up tension, but it is more preferable that the take-up tension is tapered and taken up according to the take-up diameter.
It is also necessary to adjust the draw ratio between the nip rolls so that the film does not receive a tension higher than the specified tension in the middle of the line.
Prior to winding, a laminate film may be attached to at least one side.

<Solution casting>
Next, the preferable form in the case of manufacturing the cellulose derivative of this invention with a solution casting method is demonstrated.
In the present invention, the solvent of the cellulose derivative is not particularly limited as long as the cellulose derivative can be dissolved, cast, and formed into a film and the object can be achieved. Preferred solvents include chlorinated organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, tetrachloroethylene, and non-chlorinated organic solvents.
The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The non-chlorine organic solvent used in the present invention is not particularly limited as long as the object can be achieved within the range in which the cellulose derivative can be dissolved, cast, and formed into a film. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is necessary to use at least 50% by mass of dichloromethane. The non-chlorine organic solvent used in combination with the present invention is described below. That is, as a preferable non-chlorine organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. Esters, ketones, ethers and alcohols may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a solvent. For example, other functional groups such as alcoholic hydroxyl groups can be used. You may have group simultaneously. In the case of a 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 esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and among them, saturated aliphatic hydrocarbon is preferable. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.

  The non-chlorine organic solvent used in combination with the chlorine-based organic solvent that is the main solvent used in the above cellulose derivative is not particularly limited, but methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, dioxane, It is selected from ketones or acetoacetates having 4 to 7 carbon atoms, alcohols or hydrocarbons having 1 to 10 carbon atoms. Preferred non-chlorine organic solvents used in combination are methyl acetate, acetone, methyl formate, ethyl formate, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. , 2-butanol, and cyclohexanol, cyclohexane, and hexane.

  The cellulose derivative of the present invention is preferably dissolved in an organic solvent in an amount of 10 to 35% by mass. More preferably, it is 13-30 mass%, and it is especially preferable that it is the cellulose derivative solution which 15-28 mass% is melt | dissolving. The method of carrying out the cellulose derivative at these concentrations may be carried out so that the cellulose derivative has a predetermined concentration at the stage of dissolution, or a concentration step which will be described later after being prepared in advance as a low concentration solution (for example, 9 to 14% by mass). May be adjusted to a predetermined high concentration solution. Furthermore, after adding a high concentration cellulose derivative solution in advance, various additives may be added to obtain a predetermined low concentration cellulose derivative solution. If there is no problem.

  Regarding the preparation of the cellulose derivative solution (dope) of the present invention, the dissolution method is not particularly limited, and may be room temperature, and further, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. With respect to these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511, Special JP-A-2000-273184, JP-A-11-323017, JP-A-11-302388, etc. describe methods for preparing a cellulose derivative solution. The above-described method for dissolving these cellulose derivatives in an organic solvent is applicable to the present invention as long as it is within the scope of the present invention. The details of these methods, particularly for non-chlorinated solvent systems, are described in detail on pages 22 to 25 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). Will be implemented. Furthermore, the cellulose derivative solution of the present invention is usually concentrated and filtered, and similarly described in detail on page 25 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). Has been. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

  The cellulose derivative solution of the present invention preferably has a viscosity and a dynamic storage modulus within the range. 1 mL of the sample solution was measured with a rheometer (CLS 500) using a Steel Cone having a diameter of 4 cm / 2 ° (both manufactured by TA Instruments). Measurement conditions were measured by varying the range from 40 ° C. to −10 ° C. at 2 ° C./min using an Oscillation Step / Temperature Ramp, static non-Newtonian viscosity n * (Pa · s) at 40 ° C. and storage at −5 ° C. The elastic modulus G ′ (Pa) was determined. Note that the measurement was started after the sample solution was kept warm until the liquid temperature became constant at the measurement start temperature. In the present invention, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s, The dynamic storage elastic modulus at 15 ° C. is preferably 1 to 1,000,000. Furthermore, it is preferable that the dynamic storage elastic modulus at a low temperature is large. For example, when the casting support is −5 ° C., the dynamic storage elastic modulus is preferably 10,000 to 1,000,000 Pa at −5 ° C. When a body is -50 degreeC, it is preferable that the dynamic storage elastic modulus in -50 degreeC is 10,000-5 million Pa.

(Specific method of solution casting)
Next, the manufacturing method of the cellulose derivative film of this invention is described. As a method and equipment for producing the cellulose derivative film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose derivative film are used. The dope (cellulose derivative solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support. The both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for silver halide photographic light-sensitive materials and functional protective films for electronic displays, in addition to the solution casting film forming apparatus, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. In many cases, a coating device is added to the surface processing of the film. Each of these manufacturing processes is described in detail on pages 25 to 30 of the Japan Society of Invention Public Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society of Invention). Including), metal support, drying, peeling, stretching, etc.

  Here, although the space temperature of a casting part is not specifically limited in this invention, It is preferable that it is -50-50 degreeC. Furthermore, it is preferable that it is -30-40 degreeC, and it is especially preferable that it is -20-30 degreeC. In particular, the cellulose derivative solution cast at a low space temperature can be cooled on the support instantly to increase the gel strength, thereby holding the film containing the organic solvent. Thereby, without evaporating the organic solvent from the cellulose derivative, it can be peeled off from the support in a short time, and high-speed casting can be achieved. The means for cooling the space may be normal air, nitrogen, argon, helium or the like, and is not particularly limited. In that case, the relative humidity is preferably 0 to 70%, more preferably 0 to 50%. Moreover, in this invention, the temperature of the support body of the casting part which casts a cellulose derivative solution is -50-130 degreeC, Preferably it is -30-25 degreeC, Furthermore, it is -20-15 degreeC. In order to keep the casting part at the temperature of the present invention, it may be achieved by introducing a cooled gas into the casting part, or a cooling device may be arranged in the casting part to cool the space. At this time, it is important to take care not to attach water, and it can be carried out by a method such as using dry gas.

  In the present invention, the following configurations are particularly preferred for the contents and casting of each layer. That is, the cellulose derivative solution is a cellulose derivative solution containing 0.1 to 20% by mass of at least one liquid or solid plasticizer with respect to the cellulose derivative at 25 ° C. and / or at least one kind. A cellulose derivative solution containing 0.001 to 5% by mass of a liquid or solid UV absorber based on the cellulose derivative, and / or an average particle size of 5 to 3000 nm of at least one solid. It is a cellulose derivative solution containing 0.001 to 5% by mass of a certain fine particle powder with respect to the cellulose derivative, and / or 0.001 to 0.001 of at least one fluorosurfactant with respect to the cellulose derivative. And / or at least one cellulose derivative solution containing 2% by mass It is a cellulose derivative solution containing 0.0001 to 2% by mass of a release agent with respect to the cellulose derivative, and / or contains 0.0001 to 2% by mass of at least one kind of deterioration inhibitor with respect to the cellulose derivative. And / or at least one optical anisotropy control agent is contained in an amount of 0.1 to 15% by mass with respect to the cellulose derivative, and / or at least one red It is preferably a cellulose derivative solution characterized by being a cellulose derivative solution containing 0.1 to 5% by mass of an external absorbent with respect to the cellulose derivative, and a cellulose derivative film produced therefrom.

  In the casting step, one type of cellulose derivative solution may be cast in a single layer, or two or more types of cellulose derivative solutions may be co-cast simultaneously and / or sequentially. In the case of having a casting process comprising two or more layers, in the cellulose derivative solution and the cellulose derivative film to be produced, the composition of the chlorinated solvent in each layer is either the same or different, and the addition of each layer The additive is either one type or a mixture of two or more types, the addition position of the additive to each layer is either the same layer or a different layer, in the additive solution The concentration of each layer is either the same concentration or a different concentration, the aggregate molecular weight of each layer is either the same or a different aggregate molecular weight, and the temperature of the solution in each layer is Either the temperature is the same or different, the coating amount of each layer is either the same or different, and the viscosity of each layer is the same or different It is either one of the viscosities, the thickness of each layer after drying is the same or different thickness, and the materials present in each layer are the same or different or different A cellulose derivative solution characterized in that the physical properties of each layer are either the same or different physical properties, and the physical properties of each layer are either uniform or a distribution of different physical properties And a cellulose derivative film prepared from the solution thereof. Here, the physical properties include physical properties described in detail on pages 6 to 7 of the Japan Society of Invention Public Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society of Inventions). Haze, transmittance, spectral characteristics, retardation Re, Rth, molecular orientation axis, axial misalignment, tear strength, folding strength, tensile strength, roll-in / out Rt difference, creaking, dynamic friction, alkali hydrolysis, curl value, moisture content , Residual solvent amount, heat shrinkage rate, high humidity dimensional evaluation, moisture permeability, base flatness, dimensional stability, heat shrinkage start temperature, elastic modulus, and measurement of bright spot foreign matter, and base evaluation The impedance and surface shape used in the above are also included. In addition, the Yellow Index, Transparency, Thermophysical Properties (Tg, Crystallization) of Cellulose Derivatives described in detail on page 11 of the Japan Institute of Invention Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention) Heat).

<Treatment of cellulose derivative film>
(Stretching)
As described above, the cellulose derivative film of the present invention produced by the melt film forming method or the solution film forming method is stretched for the purpose of improving the surface shape, expressing Re, Rth, improving the linear expansion coefficient, and the like. Is preferred.
Stretching may be performed on-line during the film-forming process, or may be performed off-line after winding up once after film-forming is completed. That is, in the case of melt film formation, the stretching may be performed without completion of cooling during film formation, or may be performed after completion of cooling.
Stretching is preferably performed at Tg to (Tg + 50 ° C.), more preferably (Tg + 1 ° C.) to (Tg + 30 ° C.), and particularly preferably (Tg + 2 ° C.) to (Tg + 20 ° C.). A preferable draw ratio is 0.1% to 500%, more preferably 10% to 300%, and particularly preferably 30% to 200%. These stretching operations may be performed in one stage or in multiple stages. The draw ratio here is determined using the following equation.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / Length before stretching

Such stretching is performed by longitudinal stretching, lateral stretching, and combinations thereof. Longitudinal stretching includes (1) roll stretching (stretching in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side), (2) fixed end stretching (holding both ends of the film, And the like can be used. Further, for the transverse stretching, tenter stretching (stretching by stretching both sides of the film with a chuck and stretching it in the transverse direction (perpendicular to the longitudinal direction)) can be used. These longitudinal stretching and lateral stretching may be performed alone (uniaxial stretching) or in combination (biaxial stretching). In the case of biaxial stretching, it may be carried out in the longitudinal and transverse sequential manners (sequential stretching) or simultaneously (simultaneous stretching).
The stretching speed of longitudinal stretching and lateral stretching is preferably 10% / min to 10000% / min, more preferably 20% / min to 1000% / min, particularly preferably 30% / min to 800% / min. In the case of multi-stage stretching, the average value of the stretching speed of each stage is indicated.

Following such stretching, it is also preferable to relax by 0% to 10% in the longitudinal or transverse direction. Furthermore, it is also preferable to heat-fix at 150 to 250 degreeC for 1 second-3 minutes following extending | stretching.
The film thickness after stretching in this manner is preferably 10 to 300 μm, more preferably 20 μm to 200 μm, and particularly preferably 30 μm to 100 μm.

  The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, the closer to 0 °, the better, preferably 0 ± 3 °, more preferably 0 ± 2 °, and particularly preferably 0 ± 1 °. In the case of transverse stretching, 90 ± 3 ° or −90 ± 3 ° is preferable, 90 ± 2 ° or −90 ± 2 ° is more preferable, and 90 ± 1 ° or −90 ± 1 ° is particularly preferable.

  The above-mentioned unstretched or stretched cellulose derivative film may be used alone, or may be used in combination with a polarizing plate, a liquid crystal layer or a layer with a controlled refractive index (low reflective layer) or A hard coat layer may be provided for use.

(Photoelastic coefficient)
The cellulose derivative film of the present invention is preferably used as a polarizing plate protective film or a retardation plate. When used as a polarizing plate protective film or a retardation plate, the birefringence (Re, Rth) may change due to the stress due to expansion and contraction due to moisture absorption. Such a change in birefringence due to the stress can be measured as a photoelastic coefficient, and the range is preferably 5 × 10 ⁻⁷ (cm ² / kgf) to 30 × 10 ⁻⁷ (cm ² / kgf). More preferably, it is preferably 10 × 10 ⁻⁷ (cm ² / kgf) to 25 × 10 ⁻⁷ (cm ² / kgf), and 7 × 10 ⁻⁷ (cm ² / kgf) to 20 × 10 ⁻⁷ (cm ² / kgf). It is particularly preferred.

(surface treatment)
The cellulose derivative film that has not been stretched or has been stretched can optionally be subjected to surface treatment to achieve improved adhesion between the cellulose derivative film and each functional layer (for example, the undercoat layer and the back layer). . For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Among these, alkali saponification treatment is particularly preferable, and it is extremely effective as the surface treatment of the cellulose derivative film.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the dipping method, it can be achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 to 10 minutes, and then neutralizing, washing with water and drying. .

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during the alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or acid, and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods are described in JP 2002-82226 A and WO 02/46809 pamphlet.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be applied after the above surface treatment or may be applied without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Institute of Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

<Combination with functional layer>
Combining the cellulose derivative film of the present invention with the functional layer described in detail on pages 32 to 45 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). Is preferred. Among these, application of a polarizing film (formation of a polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

[Polarizing film]
(Polarized film material)
At present, commercially available polarizing films are generally made by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. is there. The polarizing film is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used.
Iodine and dichroic dye in the polarizing film exhibit polarizing performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (for example, sulfo, amino, hydroxyl). For example, the compounds described in page 58 of the Japan Society of Invention Disclosure Technique (Public Technical No. 2001-1745, published on March 15, 2001, Japan Society of Invention).

  As the binder of the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913, Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like are included. Silane coupling agents can be used as the polymer.

Of these, water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are preferable. Further preferred. It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%.
The polymerization degree of polyvinyl alcohol is preferably 100 to 5000.

The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.
The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), more preferably 25 μm or less, and particularly preferably 20 μm or less.

  The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (for example, boric acid and borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved.

  Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

(Stretching of polarizing film)
The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement by the wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. The draw ratio here represents (length of the polarizing film after stretching / length of the polarizing film before stretching). Stretching may be performed in parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification. More preferred is oblique stretching in which the film is stretched with an inclination of 10 to 80 degrees in the oblique direction.

(A) Parallel stretching method Prior to stretching, the PVA film is swollen. The degree of swelling is usually 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of usually 15 to 50 ° C., preferably 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be performed by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip rolls to be higher than that of the preceding nip rolls. The stretching ratio (after stretching / the length ratio in the initial state: the same hereinafter) is 1.2 to 3.5 times, more preferably 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. Then, it is made to dry at 50 to 90 degreeC, and a polarizing film is obtained.

(B) Diagonal stretching method The oblique stretching method can be carried out by stretching using a tenter projecting in the tilting direction, as described in JP-A-2002-86554. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.
The temperature during stretching is preferably 40 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. The relative humidity is preferably 50% to 100%, more preferably 70% to 100%, and particularly preferably 80% to 100%. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.

After the end of stretching, the film is preferably dried at 50 to 100 ° C., more preferably 60 to 90 ° C., preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and particularly preferably 45 ° (40 ° to 50 °).

(Lamination)
The saponified cellulose derivative film and a polarizing film prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably performed so that the casting axis direction of the cellulose derivative film and the stretching axis direction of the polarizing plate are 45 °.
The adhesive for bonding is not particularly limited, and examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.

  The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and particularly preferably in the range of 40 to 50% in the light with a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and particularly preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce a circularly polarizing plate. In this case, lamination is performed so that the slow axis of the λ / 4 plate and the absorption axis of the polarizing plate are 45 degrees. At this time, the λ / 4 plate is not particularly limited, but more preferably has a wavelength dependency such that the retardation becomes smaller as the wavelength becomes lower. Furthermore, it is preferable to use a polarizing film having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

[Addition of optical compensation layer (creation of optical compensation sheet)]
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the cellulose derivative film and further provides the optically anisotropic layer. Is formed.

(Alignment film)
An alignment film is provided on the surface-treated cellulose derivative film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after the alignment of the liquid crystalline compound, the alignment film plays the role and is not necessarily an essential component. That is, it is possible to produce a polarizing plate using the cellulose derivative film of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.

  The alignment film is an organic compound (for example, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, the crosslinkability has a function of bonding side chains having a crosslinkable functional group (for example, a double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional group into the side chain.

  As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph [0022] of JP-A-8-338913, for example. ), Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are particularly preferable. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state.

  For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy groups, dialkoxy groups, monoalkoxy groups), and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426, for example. Etc.

  When the side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer or the crosslinkable functional group is introduced into the side chain having the function of aligning liquid crystal molecules, the alignment film polymer and optical anisotropy are obtained. The polyfunctional monomer contained in the layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] of JP-A No. 2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.

  Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [0024] of JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without generation of reticulation can be obtained. May occur.

  The alignment film can be basically formed by applying the polymer on the transparent support containing the alignment film forming material and the crosslinking agent, followed by drying by heating (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating liquid is preferably a mixed solvent of an organic solvent (for example, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optically anisotropic layer reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heat drying can be normally performed at 20 degreeC-110 degreeC. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is more preferable. The drying time can usually be 1 minute to 36 hours, but is preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is usually 4.5 to 5.5, and 5 is particularly preferable.

The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment step performed when manufacturing a liquid crystal display device can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.

When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film with the polarizing film being transported. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll can be any. Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used in a liquid crystal display device, 40 to 50 ° is preferable. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

(Optically anisotropic layer)
Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, if necessary, the alignment film polymer is reacted with the polyfunctional monomer contained in the optically anisotropic layer, or the alignment film polymer is crosslinked using a crosslinking agent.
The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

1) Rod-like liquid crystalline molecules As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemical Chemistry of the Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable group and the polymerization described in paragraphs [0064] to [0086] of JP-A-2002-62427 are exemplified. Liquid crystal compounds.

2) Discotic liquid crystalline molecules The discotic liquid crystalline molecules include benzene derivatives described in the research report of C. Destrade et al., Mol. Cryst. 71, 111 (1981), C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990). Torxene derivatives, B. Kohne et al., Angew Chem. 96, 70 (1984) cyclohexane derivatives and JMLehn et al., J. Chem. Commun., 1794 (1985), J. Zhang et al., J. Am Chem. Soc. 116, 2655 (1994), including azacrown and phenylacetylene macrocycles.

  As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] of JP-A No. 2000-155216.

  In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing film side can be generally adjusted by selecting the discotic liquid crystalline molecules or the material of the alignment film, or by selecting the rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

(Other composition of optically anisotropic layer)
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. It is preferable that the liquid crystal molecules have compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or do not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer, and the thing which shows copolymerizability with respect to the liquid crystal compound which has said polymeric group is preferable. Examples thereof include those described in paragraph numbers [0018] to [0020] of JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1% by mass to 50% by mass and preferably in the range of 5% by mass to 30% by mass with respect to the discotic liquid crystalline molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] of JP-A No. 2001-330725.

  The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.

  Examples of the polymer include cellulose acylate. Preferable examples of cellulose acylate include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1% by mass to 10% by mass with respect to the liquid crystalline molecule so as not to inhibit the alignment of the liquid crystal molecules. More preferably, it is in the range.

  The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(Formation of optically anisotropic layer)
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerizable initiator described later and optional components on the alignment film.
As the solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The coating liquid can be applied by a known method (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and particularly preferably 1 to 10 μm.

(Fixing the alignment state of liquid crystalline molecules)
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (US Pat. No. 2,448,828). Description), α-hydrocarbon substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2,951,758). ), A combination of triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compound (Japanese Patent Laid-Open No. 60-105667), U.S. Pat. No. 4,239,850) and oxadiazole compounds (described in U.S. Pat. No. 4,212,970).

The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
Light irradiation for polymerizing liquid crystalline molecules is preferably performed using ultraviolet rays.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, and particularly preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

(Combination with polarizing film)
It is also preferable to combine this optical compensation film and a polarizing film. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is produced. . When a polarizing plate using the cellulose derivative film of the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.

  The tilt angle of the polarizing film and the optical compensation layer may be stretched so as to match the angle formed by the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

[Application of antireflection layer (production of antireflection film)]
In general, the antireflection film transparently supports a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (ie, a high refractive index layer and a medium refractive index layer). It is provided on the body.
As a method of forming a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) having different refractive indexes are laminated, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or a sol-gel method of a metal compound such as a metal alkoxide. Examples thereof include a method of forming a thin film after forming a colloidal metal oxide particle film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310).

On the other hand, various antireflection films in which thin films are laminated by applying a dispersion in which inorganic particles are dispersed in a matrix have been proposed as antireflection films having high productivity. Examples of the antireflection film by application include an antireflection film in which a layer provided with an antiglare property having fine irregularities on the surface is formed as the uppermost layer.
The cellulose derivative film of the present invention can be applied to the antireflection film produced by any of the above methods, but is particularly preferably applied to an antireflection film produced by a coating method (coating type).

(Layer structure of coating type antireflection film)
An antireflection film consisting of a layer structure in which at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) are sequentially formed on a transparent support is designed so that the refractive index satisfies the following relationship: The
The refractive index of the high refractive index layer> The refractive index of the medium refractive index layer> The refractive index of the transparent support> The refractive index of the low refractive index layer Further, a hard coat layer is provided between the transparent support and the medium refractive index layer. May be. Further, it may be composed of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. Examples thereof include those described in JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like.

Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 etc.) etc. are mentioned.
The haze of the antireflection film is preferably 5% or less, and more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and particularly preferably 3H or more in a pencil hardness test according to JIS K5400.

(High refractive index layer and medium refractive index layer)
The layer having a high refractive index of the antireflection film is composed of a curable film containing at least an inorganic compound ultrafine particle having a high refractive index having an average particle size of 100 nm or less and a matrix binder.
The inorganic compound fine particles having a high refractive index include inorganic compounds having a refractive index of 1.65 or more, preferably inorganic compounds having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

  In order to obtain such ultrafine particles, a technique for treating the surface of the particles with a surface treatment agent (for example, described in JP-A Nos. 11-295503, 11-153703, and 2000-9908). Technology that treats with a silane coupling agent, technology that treats with an anionic compound or organometallic coupling agent described in JP 2001-310432 A, etc., technology that makes a core-shell structure with high refractive index particles as a core (For example, a technique described in JP-A-2001-166104), a technique using a specific dispersant (for example, JP-A-11-153703, US Pat. No. 6,210,858B1, JP-A-2002) Technology described in Japanese Patent Application Publication No. 2776069, etc. can be used. Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

Further, the composition is selected from a composition containing a polyfunctional compound having at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound having a hydrolyzable group, and a composition of a partial condensate thereof. At least one composition is preferred. Examples of the compounds used in these compositions include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, a curable film described in JP 2001-293818 A can be exemplified.

The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(Low refractive index layer)
The low refractive index layer is a layer formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is generally 1.20 to 1.55. Preferably it is 1.30-1.50.
The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. In order to greatly improve the scratch resistance, it is effective to impart slipperiness to the surface. Specifically, a conventionally known method for forming a thin film layer into which a silicone compound or a fluorine-containing compound is introduced can be applied. .

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. Moreover, it is preferable that a fluorine-containing compound is a compound containing the crosslinkable or polymerizable functional group which contains a fluorine atom in 35-80 mass%.

For example, paragraph numbers [0018] to [0026] of JP-A-9-222503, paragraph numbers [0019] to [0030] of JP-A-11-38202, and paragraph number [0027] of JP-A-2001-40284. To [0028], and compounds described in JP-A No. 2000-284102.
The silicone compound is a compound having a polysiloxane structure, and preferably has a curable functional group or a polymerizable functional group in the polymer chain and forms a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (manufactured by Chisso Corporation), polysiloxane having silanol groups at both ends (JP-A-11-258403, etc.) and the like can be mentioned.

The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out by light irradiation at the same time as or after coating the coating composition for forming the outermost layer containing a polymerization initiator or a sensitizer. It is preferable to carry out by heating.
A sol-gel cured film obtained by curing a condensation reaction between an organometallic compound such as a silane coupling agent and a silane coupling agent having a specific fluorine-containing hydrocarbon group in the presence of a catalyst is also preferable.

  For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly (perfluoroalkyl ether) group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002). And the like described in JP-A-53804).

The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. A low refractive index inorganic compound, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820), silane coupling agents, slip agents, surfactants, and the like.
When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and particularly preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer can be provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the organometallic compound having a hydrolyzable functional group is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.

Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and International Publication No. WOO / 46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described in the description of the high refractive index layer.
The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or more, more preferably 2H or more, and particularly preferably 3H or more in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

(Forward scattering layer)
The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.

  For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. The technique described in -107512 gazette etc. can be used.

(Other layers)
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(Application method)
Each layer of the antireflection film is formed by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, micro gravure method or extrusion coating method (US Pat. No. 2,681,294). According to the specification, it can be formed by coating.

(Anti-glare function)
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently retained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring an uneven shape onto the surface after coating (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401) Wherein) and the like.

<Liquid crystal display device>
The cellulose derivative film of the present invention, the polarizing plate using the cellulose derivative film, the retardation film and the optical film can each be preferably incorporated into a liquid crystal display. Each liquid crystal mode will be described below.

(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display)
This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. A liquid crystal display device using a bend alignment mode liquid crystal cell is disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensated Bend) liquid crystal mode.

  Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie near the cell substrate. .

  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.

(Evaluation of the physical properties)
(1) Average molecular weight It measured on the following conditions using the GPC apparatus (HLC-8220GPC by Tosoh), and calculated | required the number average molecular weight (Mn) and the weight average molecular weight (Mw). The calibration curve was prepared using polystyrene (TSK standard polyester: molecular weight 1050, 5970, 18100, 37900, 190000, 706000). The obtained average molecular weight was divided by the molecular weight per repeating unit determined from the degree of substitution determined by the method of (2) below to obtain weight average degree of polymerization (DPw) and number average degree of polymerization (DPn).
Eluent: DMF
Flow rate: 1 ml / min Detector: RI
Sample concentration 0.5%

(2) Degree of substitution
^The degree of substitution was determined by comparing the carbon area intensity ratio of the cellulose derivative by ¹³ C-NMR method.

(3) Glass transition temperature (Tg)
20 mg of a cellulose derivative film was placed in a DSC measurement pan. This was heated from 30 ° C. to 240 ° C. at 10 ° C./min in a nitrogen stream, and then cooled to 30 ° C. at −50 ° C./min. Thereafter, the temperature was raised again from 30 ° C. to 240 ° C., and the temperature at which the baseline began to deviate from the low temperature side was defined as Tg.

<Production Example> Synthesis of 6-tritylcellulose Tc-1
6-tritylcellulose Tc-1 was synthesized from cellulose (wood pulp) by the method described in Macromol. Chem. Phys., 1996, 197, 962.
The obtained 6-trityl cellulose had a number average molecular weight of 56,500 and a weight average molecular weight of 195,800.

<Example 1> Synthesis of 6-trityl-2,3-diacetylcellulose P-1 In a reaction vessel equipped with a stirrer and a cooling device, 5 parts by mass of 6-tritylcellulose and 50 parts by mass of pyridine are taken at 40 ° C. Stir to make a homogeneous solution. The mixture was cooled to 5 ° C. and 5.8 parts by mass of acetyl chloride was added over 1 hour, and then the internal temperature was raised to 50 ° C. and stirred for 8 hours. After adding 1.5 parts by mass of water and further stirring for 1 hour, the internal temperature was cooled to 25 ° C., and 50 parts by mass of acetone was added. 300 parts by mass of methanol was added, and the precipitated coarse product was collected by filtration. The operation of washing the crude product with methanol at 50 ° C. was repeated and purified to obtain 6-trityl-2,3-diacetylcellulose P-1.
The obtained 6-trityl-2,3-diacetylcellulose had a trityl substitution degree of 0.95, an acetyl substitution degree of 2.0, a number average molecular weight of 63,000, and a weight average molecular weight of 214200.

<Example 2> Synthesis of 6-trityl-2,3-dipropionylcellulose P-2 In a reaction vessel equipped with a stirrer and a cooling device, 5 parts by mass of 6-tritylcellulose and 50 parts by mass of pyridine were taken, and 40 ° C. To prepare a uniform solution. The mixture was cooled to 5 ° C. and 6.8 parts by mass of propionyl chloride was added over 1 hour, and then the internal temperature was raised to 50 ° C. and stirred for 8 hours. After adding 1.5 parts by mass of water and further stirring for 1 hour, the internal temperature was cooled to 25 ° C., and 50 parts by mass of acetone was added. 300 parts by mass of methanol was added, and the precipitated coarse product was collected by filtration. The operation of washing the crude product with methanol at 50 ° C. was repeated and purified to obtain 6-trityl-2,3-dipropionylcellulose P-2.
The obtained 6-trityl-2,3-diacetylcellulose had a trityl substitution degree of 0.95, a propionyl substitution degree of 2.0, a number average molecular weight of 65300, and a weight average molecular weight of 225,000.

<Example 3> Synthesis of 6-trityl-2,3-dibutyrylcellulose P-3 In a reaction vessel equipped with a stirrer and a cooling device, 5 parts by mass of 6-tritylcellulose and 50 parts by mass of pyridine were taken, and 40 ° C. To prepare a uniform solution. The mixture was cooled to 5 ° C., 8 parts by weight of butyric chloride was added over 1 hour, and the internal temperature was raised to 50 ° C. and stirred for 8 hours. After adding 1.5 parts by mass of water and further stirring for 1 hour, the internal temperature was cooled to 25 ° C., and 50 parts by mass of acetone was added. 300 parts by mass of methanol was added, and the precipitated coarse product was collected by filtration. The operation of washing the crude product with methanol at 50 ° C. was repeated and purified to obtain 6-trityl-2,3-dibutyrylcellulose P-3.
The obtained 6-trityl-2,3-dibutyryl cellulose had a trityl substitution degree of 0.95, a butyryl substitution degree of 1.7, a number average molecular weight of 70300, and a weight average molecular weight of 222300.

<Example 4> Synthesis of 6-trityl-2,3-dipropionylcellulose P-4 In a reaction vessel equipped with a stirrer and a cooling device, 5 parts by mass of 6-tritylcellulose and 50 parts by mass of pyridine were taken, and 40 ° C. To prepare a uniform solution. The mixture was cooled to 5 ° C., and 3.0 parts by mass of propionyl chloride was added over 1 hour, and then the internal temperature was raised to 50 ° C. and stirred for 8 hours. After adding 1.5 parts by mass of water and further stirring for 1 hour, the internal temperature was cooled to 25 ° C., and 50 parts by mass of acetone was added. 300 parts by mass of methanol was added, and the precipitated coarse product was collected by filtration. The operation of washing the crude product with methanol at 50 ° C. was repeated and purified to obtain 6-trityl-2,3-dipropionylcellulose composition P-4.
The obtained 6-trityl-2,3-dipropionyl cellulose had a trityl substitution degree of 0.95, a propionyl substitution degree of 1.85, a number average molecular weight of 62000, and a weight average molecular weight of 206700.

<Example 5> Melt film formation (1) Preparation of sample Cellulose derivatives prepared in Examples 1 to 4 and acetylcellulose CTA-1 (substitution degree 2.85) as a comparative example, Sumilizer GP (Sumitomo) as a heat stabilizer (Chemical Industry) 0.3% by mass and Adeka Stub LA-31 (Asahi Denka Kogyo Co., Ltd.) 1% by mass as an ultraviolet absorber were added and stirred well.

(2) Melt film formation After the cellulose derivative was formed into cylindrical pellets having a diameter of 3 mm and a length of 5 mm, the cellulose derivative was dried for 6 hours with a vacuum dryer at 110 ° C. to make the residual moisture 0.01% by mass or less. This was put into a hopper adjusted to (Tg-10 ° C), and under a nitrogen stream, a full flight screw with a melting temperature of 230 ° C and a compression ratio of 3.5 was used, and L (screw length) / D (screw Kneading and melting at (diameter) = 30.
Further, after the breaker plate type filtration was performed at the outlet of the extruder, after passing through the gear pump, it was passed through a 4 μm stainless leaf type disk filter type filtration device.
CTA-1 outside the present invention could not be pelletized under the above conditions.

Pellets excluding CTA-1 were extruded through a T die and formed into a film using the touch roll described in Example 1 of JP-A-11-235747. This was peeled off from the casting roll and wound up. In addition, after trimming both ends (each 3% of the total width) just before winding, the both ends were subjected to thicknessing processing (knurling) having a width of 10 mm and a height of 50 μm, and then wound into a roll. The organic solvent content (by gas chromatography method) of these films was 0.01% by mass or less.
The surface state of these films was visually observed, and the level at which no flow streaks were detected was judged good. Further, the light transmittance in terms of 100 μm was measured.

  It was confirmed that the film prepared from the cellulose derivative of the present invention exhibits good properties.

<Example 6> Solution casting (preparation of cellulose derivative solution)
(I) Preparation of Solvent A solvent having a solvent composition consisting of dichloromethane (82.0% by mass), methanol (15.0% by mass) and butanol (3.0% by mass) was prepared.

(Ii) Drying of cellulose derivative composition The above-mentioned cellulose derivative composition was dried to a water content of 0.5% or less.

(Iii) Addition of additive The additive having the following composition was added to the solvent obtained in (i). In addition, all the following addition amounts (mass%) are the ratio with respect to the absolute dry mass of a cellulose derivative.
[Additive composition]
Plasticizer A (triphenyl phosphate) 3.1% by mass
Plasticizer B (biphenyldiphenyl phosphate) 1% by mass
Optical anisotropy control agent (plate-like compound described in (Chemical Formula 1) described in JP-A-2003-66230) 2.95% by mass
UV agent a (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3
5-triazine) 0.5% by mass
UV agent b (2 (2′-hydroxy-3 ′, 5′-di-tert-
Butylphenyl) -5-chlorobenzotriazole) 0.2% by mass
UV agent c (2 (2′-hydroxy-3 ′, 5′-di-tert-
(Amylphenyl) -5-chlorobenzotriazole) 0.1% by mass
Citric acid ethyl ester (monoester: diester = 1: 1) 0.2% by mass

(Iv) Swelling / Dissolution Each cellulose derivative of (ii) was added to the solution containing the additive obtained in (iii) with stirring. After the stirring was stopped, the slurry was swelled at 25 ° C. for 3 hours to prepare a slurry. The slurry was stirred again to completely dissolve the cellulose derivative.

(V) Filtration / concentration Thereafter, the slurry is filtered with a filter paper having an absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further a filter paper having an absolute filtration accuracy of 2.5 μm (PH, FH025). ) To obtain a cellulose derivative solution. The concentration of the cellulose derivative solution was 25% by mass (total solid content × 100 / (total solid content + solvent amount)).

(Solution casting)
The above cellulose derivative solution was heated to 35 ° C. and cast on a mirror surface stainless steel support by the following band method. In the band method, the cellulose derivative solution was passed through a Giesser and cast onto a mirror surface stainless steel support having a band length of 60 m kept at 15 ° C. The Gieseer used was similar to that described in Japanese Patent Application Laid-Open No. 11-314233. Moreover, the space temperature of the casting part was 40 ° C., and air for supplying heat was blown at a wind speed of 30 m / sec. When the residual solvent reaches 100% by mass, the cellulose derivative film is peeled off from the mirror surface stainless steel support with a load of 20 g / cm, and the temperature is increased so that the temperature increase rate is 30 ° C./min between 40 ° C. and 120 ° C. (Temperature removal). Then, after drying at 120 ° C. for 5 minutes and further at 145 ° C. for 20 minutes, it was gradually cooled at 30 ° C./minute to obtain a cellulose derivative film. The obtained film was trimmed at both ends by 3 cm, and then a knurling having a height of 100 μm was imparted to a portion 2 to 10 mm from both ends and wound into a roll.
Table 2 shows the results of evaluation of Re, Rth, surface state, and light transmittance of each cellulose derivative film obtained in accordance with the above method.

  The film prepared from the cellulose derivative of the present invention has a characteristic of expressing negative Rth, which is difficult to achieve with conventional cellulose derivatives. Moreover, the film created from the cellulose derivative of this invention has shown favorable planar shape and transparency similarly to melt film forming.

<Example 7> Application of cellulose derivative film (production and evaluation of stretched film)
The unstretched film of the present invention was stretched and MD stretched at 100% / second and TD stretched at 20% / second at a temperature 10 ° C. higher than the Tg of each cellulose derivative film. The stretching method was carried out by sequential stretching in which transverse stretching was performed after longitudinal stretching and simultaneous biaxial stretching in which longitudinal and transverse stretching were simultaneously performed. Re and Rth of the cellulose derivative film produced by such a stretching method were measured, and all the cellulose derivative films of the present invention obtained good results satisfying the following range.
Formula (i): 0 nm ≦ Re ≦ 300 nm
Formula (ii): −500 nm ≦ Rth ≦ 500 nm

(Measurement of retardation change due to humidity)
With respect to the cellulose derivative films 101 to 104, 201 to 204 of the present invention and the comparative film 205, Re and Rth were measured at 25 ° C./relative humidity 10% and 25 ° C./relative humidity 80%, and the ratio (Re (Relative humidity 80%) / Re (relative humidity 10%) and Rth (relative humidity 80%) / Rth (relative humidity 10%)). The cellulose derivative film of the present invention had good properties with a value close to 1 and small retardation change due to humidity.

(Production and evaluation of polarizing plate)
(1) Saponification of Cellulose Derivative Film Each of the unstretched cellulose derivative film of the present invention and the stretched cellulose derivative film obtained by stretching the cellulose derivative film was saponified by the following method.
A 1.5 mol / L sodium hydroxide aqueous solution was used as the saponification solution. The temperature was adjusted to 60 ° C. and the cellulose derivative film was immersed for 2 minutes. Then, after being immersed in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, it was passed through a water-washing bath.

(2) Production of Polarizing Film According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and the film was stretched in the longitudinal direction to produce a polarizing film having a thickness of 20 μm.

(3) Bonding and Evaluation After selecting the polarizing film thus obtained and two saponified unstretched and stretched cellulose derivative films and sandwiching the polarizing film therebetween, PVA (Corporation) Using a Kuraray, PVA-117H) 3% aqueous solution as an adhesive, the polarizing axis and the cellulose derivative film were laminated so that the longitudinal direction was 90 °. Among these, an unstretched and stretched cellulose derivative film is attached to a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261 at 25 ° C. and 60% relative humidity. Brought into the humidity 10%. Any of the films using the cellulose derivative film of the present invention had a small change in color tone and good performance with little display unevenness.
In addition, according to Example 1 of Japanese Patent Application Laid-Open No. 2002-86554, a polarizing plate stretched using a tenter so that the stretching axis is inclined at 45 ° is similarly prepared using the cellulose derivative film of the present invention. As with the above, good results were obtained. Furthermore, when it was used for the IPS liquid crystal device described in Example 6 of JP-A-2005-206732, a liquid crystal display device having a wide contrast viewing angle and preferable was obtained.

(Production and evaluation of optical compensation film)
Instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, the above-described saponified stretched cellulose derivative film of the present invention was used, and this was used as JP-A-2002-62431. The bend-aligned liquid crystal cell described in Example 9 was attached at 25 ° C. and 60% relative humidity, and was brought into 25 ° C. and 10% relative humidity. When the cellulose derivative film of the present invention was used, good display performance with a small change in contrast was obtained.

Furthermore, in place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, the stretched cellulose derivative film of the present invention was used to produce an optical compensation filter film. In this case as well, a good optical compensation film could be produced.
Further, a polarizing plate and a retardation polarizing plate using the cellulose derivative film of the present invention are used in the liquid crystal display device described in Example 1 of JP-A-10-48420 and in Example 1 of JP-A-9-26572, respectively. An optically anisotropic layer containing the discotic liquid crystal molecules described above, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and JP-A-2000- When the 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of Japanese Patent No. 154261 and the IPS type liquid crystal display device shown in FIG. 11 of Japanese Patent Application Laid-Open No. 2004-12731 were used, a good liquid crystal display device was obtained. .

(Production and evaluation of low reflection film)
According to Example 47 of the Japan Institute of Invention Disclosure (Technology No. 2001-1745, published on March 15, 2001, Invention Association), a low reflection film was produced using the above-mentioned stretched cellulose derivative film. Good optical performance was obtained using the cellulose derivative film.
Further, the low reflection film is formed by using a liquid crystal display device described in Example 1 of JP-A-10-48420, a 20-inch VA liquid crystal display device described in FIGS. 20-inch OCB type liquid crystal display device described in FIGS. 10-15 of 2000-154261, and IPS type liquid crystal display device shown in FIG. 11 of Japanese Patent Application Laid-Open No. 2004-12731. As a result, a good liquid crystal display device was obtained.

  According to the present invention, it is possible to obtain a cellulose derivative film that can be suitably used as an optical film, has excellent retardation, and has little retardation change due to humidity. Furthermore, if this cellulose derivative film is used, a high-quality retardation film, polarizing plate, optical compensation film, antireflection film and image display device can be obtained. Therefore, the present invention is a useful invention with high industrial applicability.

Claims (12)

A cellulose derivative film comprising a cellulose derivative characterized by satisfying the following formulas (1) to (3).
Formula (1): 2 ≦ A + B ≦ 3
Formula (2): 0.05 ≦ A ≦ 2.0
Formula (3): 0.05 ≦ B ≦ 2.95
(In the formula, A represents the degree of substitution of the group represented by (Ar) ₃ C— with respect to the hydrogen atom constituting the hydroxyl group of cellulose, Ar represents an aromatic group having 6 to 20 carbon atoms, and B represents the cellulose. This represents the degree of substitution of the alkanoyl group having 2 to 6 carbon atoms with respect to the hydrogen atoms constituting the hydroxyl group.) The cellulose derivative film according to claim 1, wherein the cellulose derivative satisfies the following formulas (4) to (6).
Formula (4): 2.4 <= A + B <= 3
Formula (5): 0.05 <= A <= 1.4
Formula (6): 1.0 ≦ B ≦ 2.95 The cellulose derivative film according to claim 1, wherein the group represented by (Ar) ₃ C— is a trityl group.   The cellulose derivative film according to any one of claims 1 to 3, wherein the alkanoyl group having 2 to 6 carbon atoms is an acetyl group, a propionyl group, or a butyryl group. The in-plane retardation (Re) satisfies the following formula (i), and the retardation in the thickness direction (Rth) satisfies the following formula (ii). The cellulose derivative film according to claim 1.
Formula (i): 0 nm ≦ Re ≦ 300 nm
Formula (ii): −500 nm ≦ Rth ≦ 500 nm   A cellulose derivative film obtained by stretching the cellulose derivative film according to any one of claims 1 to 5 by 0.1% to 500% in at least one direction.   The cellulose derivative film according to claim 1, wherein the residual organic solvent amount is 0.01% by mass or less.   A retardation film comprising the cellulose derivative film according to claim 1.   It is a polarizing plate which consists of a polarizing film and two protective films which pinch | interpose this polarizing film, Comprising: At least one of two protective films is a cellulose derivative film as described in any one of Claims 1-7, or A retardation film according to claim 8.   Optical having an optically anisotropic layer formed by aligning a liquid crystalline compound on the cellulose derivative film according to any one of claims 1 to 7 or the retardation film according to claim 8. Compensation film.   An antireflection film comprising an antireflection layer on the cellulose derivative film according to any one of claims 1 to 7 or the retardation film according to claim 8.   The cellulose derivative film according to any one of claims 1 to 7, the retardation film according to claim 8, the polarizing plate according to claim 9, the optical compensation film according to claim 10, and the claim 11. An image display device comprising at least one selected from the group consisting of antireflection films.