JP2010044244A - Retardation film and polarizing plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation film which is a single film without laminating and has positive wavelength dependence of retardation by which retardation increases as wavelength increases. <P>SOLUTION: The retardation film comprises a modified glucan derivative (such as a modified cellulose derivative) in which a hydroxy acid component (such as a cyclic ester) is graft-polymerized to hydroxyl groups of a glucan derivative (e.g., a cellulose derivative such as cellulose acetate), and the retardation film satisfies the expression: 0.05≤Re(450 nm)/Re(550 nm)≤0.9, wherein Re(450 nm) and Re(550 nm) denote retardation values at 450 nm wavelength and at 550 nm wavelength, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a retardation film (or retardation plate) useful as an optical element of a display device such as a liquid crystal display device, particularly wavelength dependency (positive wavelength dispersion) in which the retardation increases as the wavelength increases in the visible light region. And a polarizing plate using the retardation film.

  The retardation film is a film in which the refractive index of the polymer film is controlled in each of the three-dimensional directions, and can generally be obtained by orienting the polymer film by a stretching operation or the like. The main function of such a retardation film is to change the polarization state of light. For example, a λ / 4 plate that converts linearly polarized light into circularly polarized light, and λ / that converts the polarization vibration plane of linearly polarized light by 90 degrees. A reverse dispersion type (reverse wavelength dispersion type) retardation film such as two plates is known. That is, such a reverse dispersion type retardation film has a characteristic that the phase difference becomes larger on the longer wavelength side (reverse wavelength dispersion) in a predetermined wavelength region (for example, a region where the wavelength λ is about 400 to 700 nm). )is required.

  However, the conventional retardation film can adjust the phase difference of the light wavelength to a phase difference of λ / 4 or λ / 2 for monochromatic light, but it is a composite wave in which light beams having different wavelengths in the visible light region are mixed. When white light is incident, due to wavelength dispersibility, the form of polarized light at each wavelength is greatly different, resulting in a distribution of polarization state. As a result, for example, when a retardation film having a retardation of λ / 4 is produced, a sufficient effect is obtained only in a wavelength region where the retardation is approximately λ / 4. . There is also a problem that incident white light is converted into colored light.

  In order to solve such a problem, a broadband retardation film capable of giving a uniform retardation to light in a wide wavelength range has been studied. For example, in Japanese Patent Laid-Open No. 10-68816 (Patent Document 1), the phase difference of birefringent light is a ¼ wavelength plate and the phase difference of birefringent light is ½ wavelength. There is disclosed a retardation plate in which a half-wave plate is bonded in a state where their optical axes intersect. However, as in this document, a retardation plate that requires a quarter-wave plate and a half-wave plate cannot form an effective retardation plate with a single layer.

  Attempts have also been made to form broadband retardation films with a single film. For example, International Publication WO 00/026705 pamphlet (Patent Document 2) is a retardation film composed of a uniaxially stretched film, and the retardation at a wavelength of 450 nm and the retardation at 550 nm satisfy a predetermined relational expression, And the retardation film whose water absorption is 1% or less is disclosed. This document discloses a retardation film composed of a polycarbonate copolymer having a bisphenol skeleton and a bisphenolfluorene skeleton, and having a reverse wavelength dispersion (wavelength dependence) with a single film without lamination. Yes. However, since the retardation film is composed of a highly hydrophobic polycarbonate-based resin, it is necessary to devise a method for laminating with a polarizing plate using a polyvinyl alcohol-based resin.

  It is also known that cellulose acylate known to have various excellent optical properties is used for a retardation film. For example, in Japanese Patent No. 345779 (Patent Document 3), the birefringence Δn at a wavelength of 400 to 700 nm is larger as the wavelength is longer (for example, 0.6 <Δn · d (450) / Δn · d (550) <0). .97, 1.01 <Δn · d (650) / Δn · d (550) <1.35) A retardation plate comprising a polymer oriented film, wherein the polymer oriented film has an average refraction at the wavelength. There is disclosed a retardation plate characterized by being an oriented film of a polymer film made of cellulose acetate having a higher rate as the wavelength is shorter and having an acetylation degree of 2.4 to 2.9. In addition, this document describes that cellulose acetate having a degree of acetyl substitution of 2.5 to 2.8 achieves the object of the invention, and when the degree of acetylation is 2.8 or less, the stretching direction is the slow axis. It is described that Δn · d (450) / Δn · d (550) tends to increase as the degree of acetyl substitution decreases.

  In the example of this document, the value of Δn · d (450) / Δn · d (550) is 0.736 in a uniaxially stretched film formed of cellulose acetate having an acetylation degree of 2.661 (Example). 1) 0.894 (Example 2) in a uniaxially stretched film formed of cellulose acetate having a degree of acetylation of 2.534, and 0.659 (in a uniaxially stretched film formed of cellulose acetate having a degree of acetylation of 2.727. It is stated that a film which is Example 3) was obtained. However, cellulose acetate is poor in thermoplasticity and flexibility, and has high hygroscopicity. Therefore, in order to obtain an ideal reverse wavelength dispersion type retardation film, a plasticizer and a hydrophobizing agent are actually required. Become. Since such an additive affects wavelength dispersion, the value of Δn · d (450) / Δn · d (550) is 0.82 which is an ideal value of a reverse wavelength dispersion type retardation film. It becomes difficult to get close to with high accuracy.

Japanese Patent Application Laid-Open No. 2002-296422 (Patent Document 4) discloses that the substitution degree of acetyl group is 1.4 to 2.85, and the total substitution degree of acetyl group with propionyl group and / or butyryl group is 2.3. A method for producing a retardation film that uses a cellulose ester of ˜2.85 and is stretched 1.15 to 2.0 times under predetermined conditions is disclosed. In this document, the retardation film has a larger retardation in the wavelength range of 400 to 700 nm, and the longer the wavelength, the retardation at wavelengths of 450 nm, 550 nm, and 650 nm is R ₄₅₀ , R _550, and R ₆₅₀ , respectively. , 0.5 <R ₄₅₀ / R ₅₅₀ <1.0 and 1.0 <R ₆₅₀ / R ₅₅₀ <1.5.

Furthermore, the international publication WO2005 / 022215 pamphlet (patent document 5) discloses a retardation film formed of a cellulose derivative such as cellulose pentanate, cellulose hexanate, or cellulose heptinate acetate. This document describes that the birefringence and chromatic dispersion of the retardation film satisfy the following relationship.
(Re750 / Re550) = A1 / Δn + 1
(Re450 / Re550) = A2 / Δn−1
(Re750 / Re550) is a ratio of the retardation value at a wavelength of 750 nm to the retardation value at a wavelength of 550 nm, and indicates a value of 0.05 to 1.95. (Re450 / Re550) is the ratio of the phase difference value at a wavelength of 450 nm to the phase difference value at a wavelength of 550 nm, and shows a value of 0.05 to 1.95. Δn is birefringence at a wavelength of 550 nm of the retardation film, and shows a value of 0.001 to 0.06. A1 and A2 are constants and represent values of -0.06 to 0.06. When A1 is a positive value, A2 is a negative value. When A1 is a negative value, A2 is a positive value.

  In this document, the retardation ratio of a 77 μm-thick retardation film made from cellulose n-hexanate having a substitution number of 2.76, Re450 / Re550 is 0.91, and a longer wavelength gives a larger retardation. It can be used as an achromatic retardation film.

  However, in the cellulose esters of these documents, as in the case of the cellulose acetate, a plasticizer and a hydrophobizing agent may be necessary, and it becomes difficult to control wavelength dispersion. In particular, cellulose esters such as cellulose acetate propionate and cellulose acetate butyrate tend to generate propionic acid and butanoic acid as thermal decomposition products when heated during film formation by melt film formation or stretching. There is a risk of deteriorating sex and causing health damage. Also, cellulose esters such as cellulose n-hexanate are not industrially advantageous because their acylating agents required for synthesis are not common and are expensive.

  On the other hand, it is also known to obtain a reverse dispersion type retardation film by blending a plurality of polymers. For example, JP 2004-325523 A (Patent Document 6) discloses a resin (M1) having a positive refractive index anisotropy, a resin (M2) having a negative refractive index anisotropy, and dichroism. A single retardation film obtained by mixing a retardation adjusting agent (C) having the above is disclosed. However, the retardation film of this document requires a retardation adjusting agent. In addition, since a plurality of resins are combined, there is a risk of film characteristics being impaired, such as surface roughness. Furthermore, cycloolefin resins and polycarbonate resins used as specific resins are not sufficiently compatible with polarizing plates and are difficult to bond.

Japanese Patent Application Laid-Open No. 2007-298889 (Patent Document 7) discloses cellulose acetate C _3-4 acylate (A) having a specific substitution degree and residual hydroxyl group having a viscosity average polymerization degree different from that of component (A). A retardation film containing 0.30 or more of cellulose acylate (B) is disclosed. Japanese Patent Application Laid-Open No. 2007-310325 (Patent Document 8) includes cellulose acetate C _3-4 acylate (A) having a specific substitution degree and a sugar component composition having a larger glucose content than this component (A). A retardation film containing a cellulose acylate (B) having a hydroxyl group residual degree of 0.30 or more is disclosed. However, even in the retardation film of this document, since a plurality of cellulose acylates are used, there is a risk of surface roughness. Further, since cellulose acetate C _3-4 acylate such as cellulose acetate propionate is used, as described above, workability may be deteriorated and health damage may be caused, and it is difficult to control wavelength dependency.

  In addition, JP 2007-16137 A (Patent Document 9) discloses an optical film comprising a cellulose ester having at least a repeating unit represented by the general formula (1) or (2) as a main component. It is disclosed.

-O-A-OCO-B-CO- (1)
-O-A-CO- (2)
A and B represent a C1-C12 divalent hydrocarbon group or a C1-C12 divalent hydrocarbon group substituted with a hydroxyl group. However, A and B may be the same or different.

According to this document, the optical film may be a retardation film, and the wavelength dispersion in the in-plane retardation of the retardation film is preferably 0.7 <(R ₄₅₀ / R ₅₉₀ ) <1. 0, 1.0 <(R ₆₅₀ / R ₅₉₀ ) <1.5, more preferably 0.7 <(R ₄₅₀ / R ₅₉₀ ) <0.95, 1.01 <(R ₆₅₀ / R ₅₉₀ ) <1 .2 is described. However, there is no description about a method for making the wavelength dispersion characteristic of the retardation film reverse wavelength dispersion, and there is no description about the wavelength dispersion of cellulose ester.
JP-A-10-68816 (Claims) International Publication WO 00/026705 Pamphlet (Claims) Japanese Patent No. 345779 (claims, paragraph number [0026], Examples) JP 2002-296422 A (claims, paragraph number [0076]) International Publication WO2005 / 022215 Pamphlet (Claims, Paragraph Number [0042]) JP 2004-325523 A (Claims) Japanese Unexamined Patent Publication No. 2007-2988889 (Claims) JP 2007-310325 A (Claims) JP 2007-16137 A (claims, paragraph number [0086])

  Accordingly, an object of the present invention is to provide a retardation film having a positive wavelength dependency with a long wavelength and a large retardation with respect to the retardation, with a single film without being laminated.

  Another object of the present invention is to provide a retardation film that can reliably compensate for a phase shift even if it is a single film in a non-laminate form, as the wavelength increases in the visible light region. There is.

  Still another object of the present invention is to provide a retardation film capable of easily and accurately controlling the wavelength dependency with respect to the retardation.

  Still another object of the present invention is to provide a polarizing plate using the retardation film.

  As a result of intensive studies to achieve the above problems, the present inventors have found that a modified glucan derivative obtained by grafting a hydroxy acid component such as a lactone to a glucan derivative such as a cellulose acylate having a hydroxyl group has a positive wavelength dependency. (Reverse wavelength dispersion characteristics), the degree of such positive wavelength dependence depends on the degree of substitution of cellulose acylate, etc. When mixed, a phase difference film having a desired reverse wavelength dispersion characteristic easily without causing surface roughness of the film or deterioration of transparency observed even when cellulose acylates having different degrees of average substitution are mixed. (For example, the ratio of phase difference values at a wavelength of 450 nm and a wavelength of 550 nm, Re (450 nm) / Re (550 nm) is 0.82 or It found to be able to prepare the film in the vicinity), and completed the present invention.

  That is, the retardation film (or retardation plate) of the present invention is composed of a hydroxy acid-modified glucan derivative in which a hydroxy acid component is graft-polymerized to a hydroxyl group of a glucan derivative (such as a cellulose derivative). And the said retardation film (or retardation film) satisfies the following formula in one film (or one film without combining with a single layer film or another film) without laminating | stacking.

0.05 ≦ Re (450 nm) / Re (550 nm) ≦ 0.9
(In the formula, Re (450 nm) and Re (550 nm) indicate phase difference values at wavelengths of 450 nm and 550 nm, respectively.)
The retardation film may be composed of a plurality of hydroxy acid-modified glucan derivatives. That is, the hydroxy acid-modified glucan derivative has different reverse wavelength dispersion characteristics depending on the type of glucan derivative. Therefore, when blended, a retardation film having a reverse wavelength dispersion characteristic close to an ideal value, for example, without lamination. In one film, the retardation film satisfying the following formula can be obtained.

0.7 ≦ Re (450 nm) / Re (550 nm) ≦ 0.9
(In the formula, Re (450 nm) and Re (550 nm) are the same as above.)
In such a retardation film, the plurality of hydroxy acid-modified glucan derivatives include, for example, (A) a hydroxy acid-modified glucan derivative in which the glucan derivative is a cellulose acylate having an acyl group average substitution degree of 2.7 to 2.95. (B) The glucan derivative may be composed of a hydroxy acid-modified glucan derivative which is a cellulose acylate having an acyl group average substitution degree of 2.0 to 2.55. The modified glucan derivative is excellent in mutual compatibility, or does not cause surface roughness or decrease in transparency that occurs in blends of glucan derivatives (cellulose acylate, etc.). A retardation film having a value of / Re (550 nm) close to 0.82 can be easily obtained. When mixing such a plurality of hydroxy acid-modified glucan derivatives, the ratio between the modified glucan derivative (A) and the modified glucan derivative (B) is, for example, the former / the latter (weight ratio) = 90/10 to 10/90. It may be a degree.

In the retardation film of the present invention, typically, the glucan derivative is cellulose C _2-4 acylate, and the hydroxy acid component is hydroxy C _2-10 alkane carboxylic acid, C _4-10 lactone and C _4-10 cyclic. It is at least one selected from diesters, and the hydroxy acid component may be grafted at an average ratio of 0.1 to 4 mol in terms of hydroxy acid per 1 mol of glucose unit of the glucan derivative. In particular, the glucan derivative may be cellulose acetate and the hydroxy acid component may be C _4-10 lactone.

  The retardation film of the present invention is also excellent in various film properties. For example, the total light transmittance may be 85% or more and the haze may be 3% or less. As described above, the retardation film of the present invention does not impair transparency even if it is composed of a blend of modified glucan derivatives.

  Since the retardation film exhibits a positive wavelength dependency with respect to the retardation, it can be effectively used as a quarter wavelength plate or a half wavelength plate. Moreover, the said retardation film is suitable for lamination | stacking with a polarizing plate, and can form a circularly-polarized light or an elliptically polarizing plate by lamination | stacking with a retardation film and a polarizing plate.

  In the present invention, since the hydroxy acid component is graft-polymerized on a glucan derivative (cellulose derivative or the like), a positive wavelength dependence can be realized with respect to the retardation with a single film (retardation film) without lamination. Moreover, even if it is one film of a non-laminate form, the phase shift can be reliably compensated in the visible light region. Furthermore, since the degree of reverse wavelength dispersion can be adjusted by the average substitution degree of acyl groups and the like, the wavelength dependence of the phase difference can be easily and accurately controlled by blending a plurality of modified glucan derivatives. Moreover, even with such a blend, the surface roughness and transparency are not lowered, and the degree of reverse wavelength dispersion is simply set to the ideal value (Re (450 nm) / Re (550 nm) is about 0.82). And it can be close with high precision. Moreover, since the retardation film of the present invention is formed of a resin derived from a component such as cellulose and has excellent affinity with the polarizing plate and is easy to bond, the polarizing plate can be suitably formed.

  In the modified glucan derivative constituting the retardation film (or retardation plate), a hydroxy acid component is graft-polymerized (graft copolymerized) on the hydroxyl group (residual hydroxyl group) of the glucan derivative. That is, the hydroxy acid-modified glucan derivative is a compound in which a hydroxy acid component is graft-polymerized to the hydroxyl group of the glucan derivative. Specifically, the glucan derivative (glucan derivative having a hydroxyl group) and the hydroxyl group of the glucan derivative are hydroxylated. It is composed of a graft chain formed by graft polymerization of an acid component. The modified glucan derivative (graft) can be usually prepared by reacting (hydroxylating) a glucan derivative having a hydroxyl group with a hydroxy acid component in the absence of a solvent or in the presence of a catalyst.

[Glucan derivative]
The glucan is not particularly limited, and examples thereof include β-1,4-glucan, α-1,4-glucan, β-1,3-glucan, α-1,6-glucan and the like. Typical glucans include, for example, polysaccharides such as cellulose, amylose, starch, lentinan and dextran. Glucans can be used alone or in combination of two or more. Among these glucans, cellulose, starch (or amylose), particularly cellulose is preferable. As the cellulose, various cellulose sources such as wood pulp (coniferous pulp, hardwood pulp) and cotton linter pulp can be used. These pulps may usually contain foreign components such as hemicellulose. As the pulp, at least one kind of pulp selected from softwood pulp and linter pulp is often used. The α-cellulose content of the high-grade cellulose may be 98% or more (for example, 98.5 to 100%, preferably 99 to 100%, more preferably about 99.5 to 100%).

  The glucan derivative is a glucan derivative in which a part of the hydroxyl group of the glucose unit of the glucan is substituted (substituted by etherification, esterification, etc.), for example, the hydroxyl group of the glucose unit (or glucose skeleton) (2, In many cases, it is a derivative in which an acyl group or the like is substituted (bonded) to the hydroxyl groups located at the 3 and 6 positions and the hydroxyl group remains. The glucan derivatives having a hydroxyl group may be used alone or in combination of two or more.

  Specific examples of glucan derivatives include, for example, etherified glucans (such as cellulose ethers), esterified glucans (such as cellulose esters), and etherified and esterified glucans (such as cellulose ether esters). Is mentioned. Below, a cellulose derivative is explained in full detail as a typical glucan derivative.

Examples of the cellulose derivative include cellulose ethers [eg, alkyl cellulose (eg, C _1-4 alkyl cellulose such as methyl cellulose, ethyl cellulose, butyl cellulose), hydroxyalkyl cellulose (eg, hydroxy C _2-4 such as hydroxyethyl cellulose, hydroxypropyl cellulose, etc.). Alkyl cellulose, etc.), hydroxyalkyl alkyl cellulose (hydroxyethyl methyl cellulose, hydroxypropyl methylcellulose etc. hydroxy _C2-4 alkyl _C1-4 alkyl cellulose etc.), cyanoalkyl cellulose (cyanoethyl cellulose etc.), carboxyalkyl cellulose (carboxymethyl cellulose etc.) ), Etc.], cellulose esters (acyl cellulose or cellulose cellulose) Sylate; inorganic acid esters such as cellulose nitrate and cellulose phosphate; mixed acid cellulose esters of inorganic acids and organic acids such as cellulose nitrate acetate) and the like.

A preferred glucan derivative (especially cellulose derivative) is cellulose acylate (or cellulose ester). In the cellulose acylate, the acyl group includes, for example, an alkylcarbonyl group [for example, a C _2-10 alkylcarbonyl group such as an acetyl group, a propionyl group, a butyryl group (eg, a C _2-6 alkylcarbonyl group, preferably C _{2 -4} alkylcarbonyl group)], cycloalkylcarbonyl group (for example, _C5-10 cycloalkylcarbonyl group such as cyclohexylcarbonyl group), arylcarbonyl group (for example, _C7-12 arylcarbonyl group such as benzoyl group, etc.) ) And the like. The same or different acyl groups may be bonded to the glucose unit of cellulose. Of these acyl groups, a _C2-4 alkylcarbonyl group is preferred. In particular, among these acyl groups, at least an acetyl group is preferable. For example, only an acetyl group may be bonded to the glucose unit, and an acetyl group and another acyl group (such as a C _3-4 acyl group) May be combined.

Preferred glucans derivatives (cellulose derivatives such as cellulose acylate) is cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose C _2-4 acylate (a cellulose diacetate and cellulose acetate butyrate Cellulose acetate), and cellulose acetate is particularly preferable.

  In a glucan derivative (cellulose acylate such as cellulose acetate), the average degree of substitution of substituents (acyl group, alkyl group, etc.) is about 0.5 to 2.99 (for example, 0.7 to 2.95). The average degree of substitution of the glucan derivative (particularly cellulose acylate) is, for example, 1 to 2.95 (for example, 1.5 to 2.95), preferably 1.8 to 2.9, and more preferably May be about 1.9 to 2.85 (for example, 2.0 to 2.7). The average substitution degree of cellulose acylate is usually 2.0 to 2.9 (for example, 2.25 to 2.9), preferably 2.2 to 2.87 (for example, 2.3 to 2.87). More preferably, it may be about 2.3 to 2.85 (for example, 2.35 to 2.85), particularly about 2.35 to 2.8 (for example, 2.37 to 2.8).

  In addition, the reverse wavelength dispersion of the modified glucan derivative greatly depends on the average degree of substitution of the glucan derivative as described later, and the degree of reverse wavelength dispersion seems to increase as the average degree of substitution increases. Therefore, using such characteristics, the degree of reverse wavelength dispersion can be adjusted by combining a plurality of modified glucan derivatives derived from glucan derivatives having different average substitution degrees.

  In a glucan derivative (cellulose acylate, etc.), the ratio of hydroxyl group (remaining hydroxyl group) is, for example, 0.01 to 2.5 mol (for example, 0.05 to 2 mol) on average per 1 mol of glucose unit. ), Preferably 0.1 to 1.5 mol (for example, 0.12 to 1 mol), more preferably about 0.15 to 0.8 mol (for example, 0.18 to 0.7 mol), Also good.

  In addition, the hydroxyl group of the glucan derivative exists at the 2nd, 3rd and 6th positions of the glucose unit. The proportion of the hydroxyl group at the 6-position of such a glucan derivative may be, for example, about 30 to 80 mol%, preferably 35 to 70 mol%, more preferably about 40 to 65 mol% of the entire hydroxyl group. Usually, among the hydroxyl groups present at the 2nd, 3rd and 6th positions of the glucose unit, the hydroxy acid component seems to be easily graft polymerized to the 6th hydroxyl group. On the other hand, the wavelength dispersibility of the modified glucan derivative is greatly influenced by the acyl group of the glucan derivative, and the graft chain (or grafted hydroxy acid component) is hardly involved in the wavelength dispersibility in many cases. It seems to act in a direction to further relax the degree of sex. Therefore, when the concentration of the hydroxyl group at the 6-position is large, it is easy to adjust the degree of wavelength dispersion of the modified glucan derivative.

  Furthermore, the average degree of polymerization (viscosity average degree of polymerization) of the glucan derivative can be selected from the range of 70 or more (for example, 80 to 800), and is about 100 to 500, preferably 110 to 400, and more preferably about 120 to 350. May be.

In addition, a commercially available product may be used for the glucan derivative (such as cellulose acylate) having a hydroxyl group, or it may be synthesized by a conventional method. For example, cellulose acylate is usually obtained by activating cellulose with an organic carboxylic acid (such as acetic acid), and then using a sulfuric acid catalyst with an acylating agent (for example, an acid anhydride such as acetic anhydride) to form cellulose triacylate ( Primary cellulose acylate), decompose excess amount of acylating agent (especially acid anhydride such as acetic anhydride), adjust acylation degree by deacylation or saponification (hydrolysis or aging), It can be produced by producing secondary cellulose acylate. The acylating agent may be an organic acid halide such as acetic acid chloride, but usually C _2-6 alkanecarboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride can be used.

  In addition, about the manufacturing method of a general cellulose acylate, "Wood chemistry (the top)" (Umeda et al., Kyoritsu publication Co., Ltd. 1968 publication, page 180-190) can be referred. Japanese Patent Application Laid-Open No. 9-286801 may be referred to for a method for adjusting the substitution degree of cellulose acylate. In addition, according to the method of this literature, it is easy to obtain a cellulose acylate having a relatively large proportion of the hydroxyl group at the 6-position. Furthermore, other glucans (for example, starch and the like) can be acylated (and deacylated) in the same manner as in the case of cellulose acylate.

[Hydroxy acid component]
Examples of the hydroxy acid component include hydroxy acids (for example, hydroxyalkane carboxylic acids), cyclic esters, and the like. Cyclic esters include lactones (cyclic monoesters) and cyclic diesters. The hydroxyalkane carboxylic acid, glycolic acid, lactic (L- lactic, D- lactic acid), hydroxypropionic acid (hydro acrylic acid), alpha-oxy-butyric acid, hydroxy _{C 2-10} alkanecarboxylic acid such as 6-hydroxy hexanoic acid (Preferably α-hydroxy C _2-6 alkane carboxylic acid, more preferably α-hydroxy C _2-4 alkane carboxylic acid) and the like. In addition, the hydroxy acid may be converted to a lower alkyl ester (for example, C _1-2 alkyl ester). Among these hydroxy acids, α-hydroxy acid [particularly lactic acid (L-lactic acid, D-lactic acid, or a mixture thereof)] is particularly preferable. Hydroxy acids may be used alone or in combination of two or more. Examples of the lactone (cyclic monoester) include β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, laurolactone, enanthlactone, dodecanolactone, stearolactone, α- C _3-20 lactones such as methyl-ε-caprolactone, β-methyl-ε-caprolactone, γ-methyl-ε-caprolactone, β, δ-dimethyl-ε-caprolactone, 3,3,5-trimethyl-ε-caprolactone , Preferably C _4-15 lactone, more preferably C _4-10 lactone). Examples of the cyclic diester include C _4-15 cyclic diester such as glycolide and lactide (L-lactide, D-lactide or a mixture thereof), preferably C _4-10 cyclic diester.

Preferred hydroxy acid components include cyclic esters such as C _4-10 lactones (eg, C _4-8 lactones such as β-butyrolactone, δ-valerolactone, ε-caprolactone), C _4-10 cyclic diesters [lactide (L -C _4-8 cyclic diesters such as lactide, D-lactide, or mixtures thereof]. As the cyclic ester, usually ε-caprolactone or lactide (L-lactide, D-lactide, or a mixture thereof) is often used.

  These hydroxy acid components can be used alone or in combination of two or more. Examples of the combination of different kinds of hydroxy acid components include a combination of ε-caprolactone and lactide (L-lactide, D-lactide, or a mixture thereof).

In particular, the hydroxy acid component may be a lactone component (lactone, hydroxy acid other than α-hydroxy acid, for example, C _4-10 lactone such as ε-caprolactone). When such a hydroxy acid component is used, the reverse wavelength dispersion can be easily adjusted in combination with a glucan derivative. In addition, the lactone component is less likely to cause surface roughness and is advantageous in terms of film storage stability (or storage stability).

  The reverse wavelength dispersion of the modified glucan derivative seems to depend somewhat on the type of hydroxy acid component. Therefore, the degree of reverse wavelength dispersibility can be adjusted by appropriately selecting together with the average degree of substitution of the glucan derivative as described above, the graft ratio described later, and the like.

  The ratio of the hydroxy acid component is not particularly limited, and is, for example, 5 to 1000 parts by weight (for example, 10 to 400 parts by weight), preferably 20 to 200 parts by weight with respect to 100 parts by weight of the glucan derivative having a hydroxyl group. More preferably, it may be about 30 to 150 parts by weight (for example, 35 to 130 parts by weight, particularly 25 to 80 parts by weight), and is usually 50 to 170 parts by weight (for example, 60 to 140 parts by weight, preferably 65 parts by weight). ˜120 parts by weight).

[catalyst]
The reaction (graft polymerization reaction) depends on the type of hydroxy acid component (for example, cyclic ester), but a conventional catalyst [for example, organic acid, inorganic acid, metal (alkali metal, magnesium, zinc, tin, aluminum, etc.) And metal compounds [tin compounds (dibutyltin laurate, tin chloride), organic alkali metal compounds, organic aluminum compounds, organic titanium compounds (such as titanium alkoxide), organic zirconium compounds, etc.]]. The catalysts may be used alone or in combination of two or more.

  In particular, as a catalyst (graft polymerization catalyst), a compound that becomes a catalyst for graft polymerization (particularly, ring-opening polymerization reaction using a cyclic ester) of a hydroxy acid component (cyclic ester, etc.), and starts polymerization alone A metal complex (or a metal compound) that is not used may be used. Even if the metal complex coexists with a monomer having no hydroxyl group such as a cyclic ester, the polymerization does not start with only these two components, and has a hydroxyl group such as a glucan derivative or water existing as an impurity in the system. Polymerization can only be initiated in the presence of the compound. By using such a catalyst (and a specific solvent described later), the production of a homopolymer of the hydroxy acid component derived from the catalyst can be remarkably suppressed. Further, when such a catalyst (and a specific solvent described later) is used, the substitution degree of the acyl group does not decrease, and the glucan derivative as a raw material in the product after graft polymerization (that is, the modified glucan derivative) is used. Thus, a modified glucan derivative having a desired acyl substitution degree (and graft chain substitution degree) can be efficiently obtained.

The metal complex (metal compound) that does not initiate the polymerization is composed of a central metal and a ligand coordinated to the central metal, and a specific ligand (or a cyclic ester) constituting the metal complex. Examples of ligands that do not exhibit polymerization initiation activity or ligands that are inactive to cyclic esters include carbon monoxide, halogen atoms (such as chlorine atoms), oxygen atoms, hydrocarbons [for example, alkanes (C _1-20 alkane, etc.), cycloalkane, arene (benzene, toluene, etc.)], β-diketone (β-C _5-10 diketone, such as acetylacetone), carboxylic acid [eg, alkanoic acid (acetic acid, pentanoic acid, Aliphatic carboxylic acids such as hexanoic acid, _C1-20 alkanoic acids such as 2-ethylhexanoic acid; aromatic carboxylic acids such as benzoic acid, etc.], carbonic acid, boric acid And the like ligands (for example, halo, alkyl, acylacetonato, acyl, etc.). These ligands may be coordinated to the central metal alone or in combination of two or more.

Typical graft polymerization catalysts include metal complexes having no alkoxy groups (and hydroxyl groups) and / or amino groups (amino groups other than tertiary amino groups) as ligands, such as alkali metal compounds (alkali carbonates). Metal salts, carboxylic acid alkali metal salts such as sodium acetate), alkaline earth metal compounds (eg, alkaline earth metal carbonate carbonates, carboxylic acid alkaline earth metal salts such as calcium acetate), zinc compounds (zinc acetate, Zinc acetylacetonate, etc.), aluminum compounds (eg, trialkylaluminum), germanium compounds (eg, germanium oxide, etc.), tin compounds [eg, tin carboxylates (eg, tin octylate (eg, stannous octylate), etc.) Tin C _2-18 alkane carboxylate, preferred Or tin C _4-14 alkane carboxylate), alkyl tin carboxylate (eg mono or di C _1-12 alkyl tin C _2-18 alkane carboxylate such as dibutyltin diacetate, dibutyltin dilaurate, monobutyltin trioctylate, etc.) Tin (or tin) carboxylates such as; alkyl tin oxides (eg mono- or dialkyl tin oxides such as monobutyltin oxide, dibutyltin oxide); tin halides; tin halide acetylacetonate; inorganic acid tin (tin nitrate) Polystannoxane (for example, dihalotetraalkyl distanoxanes, distanoxanes such as diacyloxytetraalkyl distanoxane)], lead compounds (such as lead acetate), antimony Typical metal compounds or typical metal complexes such as compounds (such as antimony trioxide) and bismuth compounds (such as bismuth acetate); rare earth metal compounds (for example, rare earth metal carboxylates such as lanthanum acetate and samarium acetate), titanium compounds (titanium acetate) Transition metal compounds such as zirconium compounds (such as zirconium acetate and zirconium acetylacetonate), niobium compounds (such as niobium acetate), and iron compounds (such as iron acetate and iron acetylacetonate).

  Among these catalysts, tin-based catalysts (or tin compounds) such as tin carboxylates are particularly preferable. The catalysts may be used alone or in combination of two or more.

In the reaction (graft polymerization reaction), the ratio (use ratio) of the catalyst is, for example, 10 ⁻⁷ to 10 ⁻¹ mol, preferably 5 × 10 ^{−7 to} 5 to ¹ mol of the hydroxyl group of the glucan derivative. It may be about 10 ⁻² mol, more preferably about 10 ^{−6 to} 3 × 10 ⁻² mol.

[solvent]
In a polymerization reaction system using a hydroxy acid component (such as a cyclic ester), the use of a specific solvent with low water solubility (hydrophobic solvent) or a solvent with a low water content suppresses the influence of water as much as possible. The formation of homopolymers (such as cyclic esters) can be significantly suppressed. Therefore, it is useful to suppress polymerization of the hydroxy acid component alone (that is, formation of a homopolymer such as a cyclic ester) by combining the specific catalyst and a specific solvent. In addition, polymerization of the hydroxy acid component alone can also be suppressed by using the specific catalyst in the absence of a solvent.

  The solubility of the solvent in water at 20 ° C. (or the water content of the solvent) can be selected from the range of 10% by weight or less [eg, 0 (or detection limit) to 8% by weight], for example, 7% by weight or less (eg, , 0.0001 to 6% by weight), preferably 5% by weight or less (for example, about 0.0005 to 4% by weight), more preferably 3% by weight or less (for example, about 0.0008 to 2% by weight), In particular, it may be 1% by weight or less (for example, about 0.001 to 0.8% by weight), and 0.7% by weight or less (for example, 0. 002-0.5% by weight, preferably 0.003-0.3% by weight, more preferably 0.005-0.1% by weight, especially about 0.007-0.05% by weight). .

Specific examples of the solvent having low solubility in water include aliphatic hydrocarbons [eg, alkanes (eg, linear or branched C _7-20 alkanes such as heptane, octane, nonane, decane, etc.) ), Cycloalkane (eg, C _4-10 cycloalkane such as cyclohexane)], aromatic hydrocarbons (eg, benzene, toluene, xylene (o, m or p-xylene), C _6-12 such as ethylbenzene) Arenes, preferably C _6-10 arenes), aliphatic ketones [eg, dialkyl ketones (eg, diethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, di n-propyl ketone, diisopropyl ketone, _{C 5-15} dialkyl ketones such as diisobutyl ketone, preferably _{C 7-10} dialkyl ketones), etc.], chain ethers [for example, dialkyl ethers (e.g., di-n- propyl ether, diisopropyl ether, etc. _{C 6-10} dialkyl ether such as di-n- butyl ether), alkyl aryl ethers Non-halogen solvents such as (anisole and the like), halogen solvents and the like. Examples of halogen solvents include haloalkanes (eg, halo C _1-10 alkanes such as dichloroethane, trichloroethane, tetrachloroethane, dichloropropane), halocycloalkanes (halo C _4-10 cycloalkanes such as chlorocyclohexane), halogen-based solvents, and the like. Halogenated hydrocarbons such as aromatic hydrocarbons (halo C _6-12 arenes, preferably halo C _6-10 arenes such as chlorobenzene, dichlorobenzene, chlorotoluene, chloromethylbenzene, chloroethylbenzene, etc.) .

  Even when a solvent having a solubility in water of more than 10% by weight at 20 ° C., for example, a hydrophilic solvent, water is removed using a conventional method such as distillation or a desiccant (magnesium sulfate, etc.). It can be used effectively in the reaction. The hydrophilic solvent is not particularly limited as long as it does not have a functional group (hydroxyl group, primary or secondary amino group, etc.) that serves as a polymerization initiator (for example, a ring-opening polymerization initiator of a cyclic ester). For example, ketones (for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, etc.), esters (methyl acetate, ethyl acetate, etc.), nitrogen-containing solvents (nitromethane, acetonitrile, N-methylpyrrolidone, dimethyl) Formamide), glycols with modified terminal hydroxyl groups (for example, cellosolve acetates such as methyl glycol acetate, carbitol acetates, etc.), ethers (tetrahydrofuran, dioxane, dioxolane, etc.), sulfoxides (dimethylsulfoxide). Donado), and the like propylene carbonate. Furthermore, if necessary, an excess of a hydroxy acid component (eg, lactone, lactide, etc.) may be used as a solvent. The solvents may be used alone or in combination of two or more.

  The boiling point of the solvent is, for example, 60 ° C. or higher (for example, about 70 to 250 ° C.), preferably 80 ° C. or higher (for example, about 85 to 220 ° C.), more preferably 90 ° C. or higher (for example, about 95 to 200 ° C.). In particular, it may be 100 ° C. or higher (for example, about 105 to 180 ° C.). When the boiling point of the solvent is low, the reaction temperature is restricted and the polymerization rate is lowered.

  The ratio of the solvent can be selected from a range of 50 parts by weight or more (for example, about 55 to 500 parts by weight) with respect to 100 parts by weight of the glucan derivative, depending on the type of the solvent, for example, 60 to 450 parts by weight. (E.g. 65-400 parts by weight), preferably 60-300 parts by weight (e.g. 65-250 parts by weight), more preferably 70-200 parts by weight (e.g. 75-190 parts by weight), in particular 80-180 parts by weight. Part (for example, 85 to 170 parts by weight, preferably 90 to 150 parts by weight). The ratio of the solvent is, for example, 10 to 200 parts by weight, preferably 30 to 150 parts by weight, more preferably 40 to 120 parts by weight (for example, 50 parts by weight) with respect to 100 parts by weight of the total amount of the glucan derivative and the hydroxy acid component. ˜100 parts by weight), usually 45 to 90 parts by weight (for example, 50 to 80 parts by weight).

  The reaction between the glucan derivative and the hydroxy acid component may be carried out with as little water as possible in order to suppress the formation of a homopolymer of the hydroxy acid component and side reactions. The water content of the reaction system (liquid phase system of the reaction) is, for example, 0.5% by weight or less (0 (or detection limit) to about 0.4% by weight), and usually 0.3% by weight or less [ 0 to 0.25% by weight], preferably 0.2% by weight or less (for example, about 0.0001 to 0.18% by weight), more preferably 0.15% by weight or less (for example, 0.0005 to 0). .About 12% by weight), particularly 0.1% by weight or less (for example, about 0.001 to 0.05% by weight). In the case of grafting by a condensation reaction, a solvent having a boiling point higher than that of water may be used, and the reaction may be performed while removing water generated by azeotropic distillation. The water content of the reaction system can be adjusted by removing water from each raw material and solvent using a conventional method, for example, drying under reduced pressure, distillation, desiccant (magnesium sulfate, etc.) and the like. The moisture content can be measured according to JISK0113 (issued in 2005) using a Karl Fischer-type coulometric method moisture measuring device (CA-100, manufactured by Dia Instruments Co., Ltd.) equipped with a heating type moisture vaporizer.

  The reaction (grafting reaction) may be performed at room temperature, but is usually performed under heating or heating. Reaction temperature is 60-250 degreeC, for example, Preferably it is 80-220 degreeC, More preferably, it is 100-180 degreeC (for example, 105-170 degreeC), and about 110-160 degreeC may be sufficient normally. The reaction can be carried out in air or in an inert atmosphere (such as a rare gas such as nitrogen or helium) with stirring, and can usually be carried out in an inert atmosphere. Moreover, you may perform reaction under a normal pressure or pressurization.

  The reaction product produced by the grafting reaction may be separated and purified by a conventional method, for example, separation means such as filtration, concentration, distillation, extraction, neutralization, precipitation, or a separation means combining these.

[Modified glucan derivative]
In the retardation film of the present invention, not a glucan derivative such as a cellulose ester but a compound in which a hydroxy acid component is graft-polymerized to such a glucan derivative (modified glucan derivative), in particular, a blend of such a modified glucan derivative. use. By using a modified glucan derivative, it is possible to efficiently obtain a film that is excellent in thermoplasticity and flexibility and that can easily control wavelength dispersion.

  In the modified glucan derivative, the average degree of polymerization of the graft chain (or the average number of added moles in terms of hydroxy acid of the hydroxy acid component constituting the graft chain) is not particularly limited, but in terms of hydroxy acid (for example, hydroxy in ε-caprolactone is hydroxy. Hexanoic acid conversion, lactide conversion for lactide, etc., can be selected from the range of 1-100 (for example, 1-70), for example, 1-50, preferably 1.5-30 (for example, 1.8-25). More preferably, it may be about 2 to 20 (for example, 2.5 to 18), particularly 3 to 15, usually 1 to 20 (preferably 2 to 12, more preferably 3 to 10).

  In particular, a hydroxy acid component in which the graft chain is composed of at least an α-hydroxy acid component [for example, an α-hydroxy acid and / or a cyclic diester (for example, at least one selected from lactic acid and lactide)] undergoes graft polymerization. When the graft chain is formed, the average degree of polymerization of the graft chain is, for example, 1 to 13, preferably 1.5 to 12 (for example, 2 to 12), more preferably 2.5 in terms of hydroxy acid. -11 (for example, 3-10) grade may be sufficient. When the polymerization degree of the graft chain is adjusted to the above range, high heat resistance can be efficiently imparted to the modified glucan derivative without impairing the excellent properties of the glucan derivative (cellulose acylate, etc.).

  When the degree of polymerization or molecular weight of the graft chain (particularly the graft chain of an α-hydroxy acid component such as lactide) increases, the graft chain part may have crystallinity. In that case, when a thermal history higher than the crystallization temperature acts on the hydroxy acid-modified glucan derivative, whitening or the like is likely to occur due to crystallization. For this reason, the polymerization degree and molecular weight of the graft chain may be made relatively small (for example, the average polymerization degree is 20 or less) depending on the application.

  In the modified glucan derivative, the ratio of the grafted hydroxy acid component is, for example, 0.0001 to 10 mol (for example, average) in terms of hydroxy acid with respect to 1 mol of glucose unit of the glucan derivative (or constituting the glucan derivative). , 0.005 to 8 mol), for example, 0.05 to 5 mol (for example, 0.1 to 4 mol), preferably 0.15 to 4 mol (for example, 0.2 to 3. mol). 5 mol), more preferably 0.3 to 3 mol, usually about 0.35 to 3.2 mol, and particularly 3 mol or less (for example, 0.1 to 2.5 mol, preferably 0.1 mol). 15-2 mol, more preferably 0.2-1.8 mol), usually 1.2 mol or less {e.g. 0.02-1.2 mol (e.g. 0.05-1.2 mol), preferably Is 1 mol or less [e.g. To 1 mol (e.g., from 0.15 to 0.9 mol)], more preferably 0.2 to 1.1 moles (e.g., 0.3 to 1 mole) may be about}.

  In the modified glucan derivative, the graft-polymerized hydroxy acid component often does not have wavelength dispersibility, and the greater the proportion in the modified glucan derivative, the more the wavelength dispersibility of the modified glucan derivative is reduced (Re (450 nm ) / Re (direction in which 550 nm approaches 1) Therefore, if the proportion of the hydroxy acid component is too large, it may be difficult to obtain desired wavelength dispersibility. It is preferable to adjust to the range.

  In addition, the ratio (mol) of the hydroxy acid component is added to the whole glucose unit of a modified glucan derivative (such as cellulose acylate) regardless of whether the degree of polymerization of the graft chain is 1 or greater than 1 (or The average number of moles of grafted hydroxy acid component is shown. When the hydroxy acid component is grafted at such a relatively small ratio, the glucan derivative can be efficiently modified while maintaining the glass transition temperature of the glucan derivative (for example, cellulose acylate) without greatly decreasing.

  In the modified glucan derivative, the average degree of substitution of the graft chain (specifically, the average degree of substitution of the graft chain in which the hydroxy acid component is grafted to the hydroxyl group of the glucan derivative) is, for example, 0.01 to 2 (for example, 0.015 -1.5), preferably 0.02-1 (e.g., 0.025-0.8), more preferably 0.03-0.7 (e.g., 0.035-0.6), especially 0. It may be about 04 to 0.5 (for example, 0.045 to 0.4), usually about 0.03 to 0.3 (for example, 0.05 to 0.2). The average degree of substitution of the graft chain means the average number of moles per mole of glucose unit of the hydroxyl group derivatized by graft polymerization at the 2, 3 and 6 positions of the glucose unit, like the acyl group and the like. To do.

  In the modified glucan derivative, when the average substitution degree (number of moles) of a substituent other than the graft chain (substituted hydroxyl group, for example, acyl group) is A and the average substitution degree (number of moles) of the graft chain is B , A + B is, for example, 2.2 to 3.0, preferably 2.3 to 2.98 (for example, 2.35 to 2.97), and more preferably 2.4 to 2.95 (for example, It may be about 2.45 to 2.9).

  In the modified glucan derivative, the ratio of the average substitution degree (number of moles) of a substituent other than the graft chain (substituted hydroxyl group, for example, acyl group) to the average substitution degree (number of moles) of the graft chain is the former. / The latter = 40/60 to 99.9 / 0.1 (for example, 50/50 to 99.5 / 0.5), preferably 70/30 to 99/1 (for example, 75/25 to 98.5 / 1.5), more preferably about 80/20 to 98/2 (for example, 85/15 to 97.5 / 2.5).

  In the modified glucan derivative, the ratio of the hydroxyl group (residual hydroxyl group) can be selected, for example, from an average range of 0 to 1.2 moles per 1 mole of glucose unit, for example, 0.01 to 1 mole ( For example, it may be 0.02 to 0.8 mol), preferably 0.03 to 0.7 mol, more preferably 0.04 to 0.6 mol, and usually about 0.05 to 0.55 mol. .

In the modified glucan derivative, the substituted or derivatized group (acyl group, etc.), the degree of substitution of the graft chain, the hydroxyl group concentration, the degree of polymerization of the graft chain (molecular weight), etc. can be determined by conventional methods such as nuclear magnetic resonance. It can be measured using spectrum (NMR) ( ¹ H-NMR, ¹³ C-NMR, etc.) and the like.

  The modified glucan derivative may generally have a hydroxyl group. Examples of such a hydroxyl group include a hydroxyl group at the end of a graft chain, a hydroxyl group remaining in a glucose unit, and the like. Such a hydroxyl group may be protected with a protecting group as necessary for the purpose of suppressing or adjusting the hygroscopicity of the modified graft derivative.

The protecting group is not particularly limited as long as it is a non-reactive group capable of protecting a hydroxyl group. For example, an alkyl group [e.g., a methyl group, an ethyl group, a 2-cyclohexyl-2-propyl group, a hexyl group, a chloromethyl group, A C _1-12 alkyl group (preferably a C _1-6 alkyl group) which may have a substituent such as a halogen atom], a cycloalkyl group (for example, a cyclohexyl group or the like). C _5-8 cycloalkyl group), aromatic hydrocarbon group (C _6-12 aryl group such as phenyl group, aralkyl group such as benzyl group), bridged cyclic hydrocarbon group (adamantyl group, etc.) ) hydrocarbon group such as; oxacycloalkyl group (e.g., 5- to 8-membered oxacycloalkyl group); an alkoxyalkyl group _{(e.g., C 1-6} alkoxy - _1-6 alkyl group) acetal protecting group such as; alkylcarbonyl group (acetyl, C _1-10 alkylcarbonyl group such as propionyl), a cycloalkyl group, an acyl group such as an aryl carbonyl group. A protecting group may protect a hydroxyl group individually or in combination of 2 or more types.

  In addition, the modified glucan derivative is slight, but may have a carboxyl group. Such a carboxyl group may also be protected (or sealed) in the same manner as the hydroxyl group.

  In the modified glucan derivative, the content of the homopolymer of the hydroxy acid component can be selected from a range of 15% by weight or less (for example, about 0 to 12% by weight) with respect to the whole modified glucan derivative, for example, 10% by weight. Or less (for example, about 0.05 to 9% by weight), preferably 8% or less (for example, about 0.1 to 7% by weight), more preferably 5% or less (for example, 0.1 to 4.5%). % By weight, especially about 0.1 to 3% by weight). Thus, when there is little content of the free homopolymer of a hydroxy acid component, the optical characteristics (transparency, retardation, etc.) of a retardation film can be improved.

  The glass transition temperature Tg of the modified glucan derivative (modified cellulose acylate, etc.) is, for example, 70 ° C. or higher (for example, about 73 to 220 ° C.), preferably 75 to 200 ° C. (for example, 78 to 190 ° C.), Preferably, it may be about 80 to 180 ° C. (for example, 85 to 160 ° C.), usually 90 to 155 ° C. (for example, 95 to 150 ° C.), or 100 to 180 ° C. (for example, 110). ˜175 ° C., particularly 120 ° C. to 170 ° C.).

  Furthermore, the acid value of the modified glucan derivative is usually 20 mgKOH / g or less (for example, about 0 to 18 mgKOH / g), preferably 15 mgKOH / g or less (for example, about 0.1 to 12 mgKOH / g), more preferably 10 mgKOH. / G or less (for example, about 0.3 to 9 mgKOH / g), particularly 8 mgKOH / g or less (for example, about 0.5 to 7 mgKOH / g). The acid value of the modified glucan derivative is usually about 0.2 to 10 mgKOH / g (for example, 0.4 to 8 mgKOH / g), particularly about 0.5 to 5 mgKOH / g (for example, 0.5 to 3 mgKOH / g). There may be. A modified glucan derivative having a small acid value is excellent in hydrolysis resistance. The acid value can be reduced by reducing the content of the homopolymer of the hydroxy acid component and the unreacted hydroxy acid component. The acid value can be measured by a neutralization titration method using phenolphthalein as an indicator in accordance with JISK0070 (published in 1992).

  The modified glucan derivative may contain various additives as necessary, for example, stabilizers (antioxidants, ultraviolet absorbers, peroxide decomposers, thermal stabilizers, etc.), plasticizers (phthalate ester plasticizers, fatty acids). Ester plasticizers, phosphate ester plasticizers, citrate ester plasticizers, etc.), retardation modifiers (retardation modifiers disclosed in JP-A-2001-91743, for example, 2-hydroxy-4-benzyloxybenzophenone) Benzophenone-type retardation adjusting agents such as 2,4-dibenzyloxybenzophenone), mold release agents, lubricants, colorants and the like.

  In the present invention, even if the modified glucan derivative or the retardation film does not contain a retardation adjusting agent or a plasticizer, a retardation film having reverse wavelength dispersion in a wide wavelength range can be obtained.

[Phase difference film]
The retardation film composed of the modified glucan derivative may be an unstretched film or a stretched film (uniaxial or biaxially stretched film). In many cases, the retardation film is usually an unstretched film or a uniaxially stretched film. The draw ratio can be appropriately selected from the range of about 1.05 to 5 times depending on the retardation value, for example, 1.1 to 4 times, preferably 1.15 to 3 times, more preferably 1.2 to 2 times. It may be about 5 times (for example, 1.3 to 2.2 times).

  The retardation film is effective in compensating for a phase shift with a single film without being laminated. The modified glucan derivative exhibits reverse wavelength dispersion (positive wavelength dispersion, positive wavelength dependency) when a film is formed. That is, the retardation film of the present invention exhibits a large positive wavelength dependency with respect to retardation in a single film without being laminated, and satisfies the following formula.

0.05 ≦ Re (450 nm) / Re (550 nm) ≦ 0.9
(In the formula, Re (450 nm) and Re (550 nm) indicate phase difference values (retardation values) at wavelengths of 450 nm and 550 nm, respectively).
More specifically, when Re (450 nm) / Re (550 nm) = X, the value of X is 0.1 to 0.89, preferably 0.2 to 0.88, and more preferably 0.3 to It may be about 0.87 (for example, 0.35 to 0.86).

  In the retardation film exhibiting an ideal inverse wavelength dependency, the value of X is about 0.82. In the present invention, a retardation film having an X value of 0.82 or the vicinity thereof [for example, , X is 0.7 to 0.9, preferably 0.75 to 0.89 (for example, 0.77 to 0.89), more preferably 0.78 to 0.88 (for example, 0.8. 79 to 0.87), in particular 0.8 to 0.86 (for example, 0.81 to 0.85), and usually 0.78 to 0.86 retardation film].

  As described above, the value of X can be adjusted according to the type of the modified glucan derivative. Hereinafter, typical modified glucan derivative embodiments will be described.

(A) Glucan derivative has an acyl group having an average substitution degree of 2.7 or more (for example, 2.7 to 2.95, preferably 2.705 to 2.85, more preferably 2.71 to 2.82, particularly 2 Hydroxy acid-modified glucan derivatives which are cellulose acylates (eg, cellulose C _2-4 acylates such as cellulose acetate).

  In such a modified glucan derivative (A), the value of X is relatively small [for example, the range where X satisfies 0.05 ≦ X <0.7, typically X is 0.1 to 0. 0.65, preferably 0.2 to 0.63, more preferably 0.25 to 0.6 (eg 0.3 to 0.58), especially 0.35 to 0.55]. It seems to be easy to obtain.

  Therefore, a retardation film can be constituted only by the modified glucan derivative (A), and a retardation film having a relatively small value of X can be obtained, and the modified glucan derivative (A) and the value of X are relatively large. When combined with a modified glucan derivative that easily obtains a retardation film, for example, a modified glucan derivative (B) described later, the value of X is 0.82 or the vicinity thereof [for example, the range (the value of X is 0.7 to 0). It is also possible to obtain a retardation film that is approximately.

(B) The average substitution degree of the acyl group of the glucan derivative is 2.55 or less (for example, 2.0 to 2.55, preferably 2.1 to 2.52, more preferably 2.2 to 2.5, particularly 2 Hydroxy acid-modified glucan derivative which is a cellulose acylate (for example, cellulose C _2-4 acylate such as cellulose acetate).

  In such a modified glucan derivative (B), the value of X is relatively close to 1. [For example, the range where X satisfies 0.9 <X <1; typically, X is 0.9 to 0. .99, preferably 0.9 to 0.98, more preferably 0.905 to 0.97 (for example, 0.91 to 0.96), particularly 0.91 to 0.95]. It seems to be easy to obtain.

  For this reason, the modified glucan derivative (B) often does not form the retardation film of the present invention even when the retardation film is formed alone. However, as described above, the modified glucan derivative (A) and the modified glucan described below are often used. By combining (blending) with the derivative (C) or the like to form a retardation film, the value of X is 0.82 or the vicinity thereof [for example, the range (the value of X is about 0.7 to 0.9) )] Can be prepared. In addition, in cellulose acylate and the like, when components having different average substitution degrees are mixed, the surface smoothness is impaired due to insufficient compatibility. However, in the modified glucan derivative, the graft-polymerized hydroxy acid component is A film can be formed while maintaining such properties even if they are mixed, because they may act as a binder or a compatibilizing agent that improves the compatibility between glucan derivatives. Moreover, the modified glucan derivatives have the same refractive index, and the transparency of the film is not lowered. Since the value of X can be adjusted simply by adjusting the mixing ratio as appropriate, a retardation film having ideal reverse wavelength dispersion can be easily obtained. Therefore, adjustment of X by blending is very useful. It is.

(C) The average substitution degree of the acyl group of the glucan derivative is 2.55 to 2.7 [for example, 2.555 to 2.68, preferably 2.56 to 2.66, more preferably 2.57 to 2.65. In particular, a hydroxy acid-modified glucan derivative which is a cellulose acylate (for example, cellulose C _2-4 acylate such as cellulose acetate) of about 2.59 to 2.65 (for example, about 2.6 to 2.64).

  With such a modified glucan derivative (C), it is easy to obtain a retardation film having an X value of 0.82 or the vicinity thereof [for example, the above range (the X value is about 0.7 to 0.9)]. It is. Therefore, the modified glucan derivative (C) can form a retardation film as it is, thereby obtaining a retardation film having ideal reverse wavelength dispersion. In order to make the value of X closer to 0.82, the modified glucan derivative (C) may be blended with the modified glucan derivative (A) and / or the modified glucan derivative (B).

In the modified glucan derivatives (A) to (C), the hydroxy acid component is particularly a lactone component (lactone, hydroxy acid other than α-hydroxy acid, for example, C _4-10 lactone such as ε-caprolactone). In many cases. In the modified glucan derivatives (A) to (C), the graft ratio, the average degree of substitution of the graft chains, the average degree of polymerization and the like can be selected from the above ranges.

  The modified glucan derivatives (A), (B), and (C) may also be used alone or in combination of two or more. For example, a plurality of modified glucan derivatives (A) and one or more modified glucan derivatives (B) may be combined, and one modified glucan derivative (A) and one or more modified glucan derivatives (B) May be combined, or a plurality of modified glucan derivatives (C) may be combined.

  As described above, the retardation film of the present invention may be composed of a modified glucan derivative mixture obtained by mixing (blending) a plurality of modified glucan derivatives. In the case of mixing, the mixing ratio can be appropriately selected according to the desired X value and according to the type of the modified glucan derivative to be mixed. For example, when the modified glucan derivative (A) and the modified glucan derivative (B) are mixed, the ratio of the former / the latter (weight ratio) = 95/5 to 5/95 (for example, 90/10 to 10 / 90), preferably 80/20 to 20/80, more preferably 75/25 to 25/75, particularly about 70/30 to 30/70. When the modified glucan derivative (A) and the modified glucan derivative (C) are mixed, the same range may be used.

  Further, when the modified glucan derivative (B) and the modified glucan derivative (C) are mixed, the ratio of the former / the latter (weight ratio) = 80/20 to 1/99 (for example, 75/25 to 3 / 97), preferably 70/30 to 5/95, more preferably 65/35 to 7/93, particularly about 60/40 to 10/90.

  The modified glucan derivative to be blended is not particularly limited, but may be usually the same or the same modified glucan derivative. For example, the mixture of modified glucan derivatives may be a mixture of modified glucan derivatives made from cellulose acylate (for example, cellulose acetate) having the same acyl group but different average degree of substitution. A mixture of modified glucan derivatives made from cellulose acylate of different degrees (for example, a mixture of cellulose acetate and cellulose propionate or cellulose butyrate, a mixture of cellulose acetate and cellulose acetate propionate, etc.) Also good. In particular, cellulose acylates having the same acyl group but different average substitution degrees are often combined. In such blends, the hydroxy acid components are also often the same or the same type (for example, the same lactones or different lactones), and may be particularly the same.

  The retardation film of the present invention has reverse wavelength dispersion particularly in the wavelength range of 450 to 550 nm, but usually has reverse wavelength dispersion even outside this wavelength region. For example, the retardation film of the present invention may satisfy the following formula.

1.00 <Re (630 nm) / Re (550 nm) ≦ 1.6
(In the formula, Re (550 nm) and Re (630 nm) indicate phase difference values at wavelengths of 550 nm and 630 nm, respectively)
More specifically, when Re (630 nm) / Re (550 nm) = Y, Y = 1.01 to 1.5, preferably 1.02 to 1.4, and more preferably 1.03 to 1.3. (For example, about 1.05-1.2) may be sufficient. In particular, in a retardation film showing an ideal inverse wavelength dependency, the value of Y is about 1.15. In the present invention, a retardation film having a Y value of 1.15 or in the vicinity thereof [for example, , Y value is 1.03 to 1.25, preferably 1.04 to 1.2 (for example, 1.05 to 1.18), more preferably about 1.06 to 1.17. It is also possible to obtain

  The retardation value of the film (in-plane retardation value Re) is measured by measuring the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction, and from these refractive index values, Each can be calculated based on the formula defined by the following formula.

Re = (nx−ny) × d
(In the formula, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, and d represents the thickness of the film.)
The retardation film of the present invention usually has a larger retardation as the wavelength increases in the visible light range, and a smaller retardation as the wavelength becomes shorter. That is, it has a positive wavelength dispersion characteristic. Therefore, it is effective in compensating for the phase shift of the light beam in the visible light range and realizing clear color reproducibility.

  The thickness of the retardation film is not particularly limited, and is, for example, 5 to 1000 μm (for example, 10 to 500 μm), preferably 20 to 300 μm (for example, 30 to 250 μm), and more preferably 50 to 200 μm (for example, 50 to 150 μm). It may be a degree.

  The retardation value (Re) of the retardation film can be selected from a range of, for example, about 1 to 1000 (for example, 2 to 800) at a wavelength of 550 nm, and usually 3 to 750 (for example, 5 to 600), preferably May be about 10 to 500 (for example, 50 to 400), more preferably about 75 to 350 (for example, 100 to 300). The retardation value can be easily adjusted depending on the degree of stretching.

  Such a retardation film has a positive wavelength dependency with respect to the retardation, can effectively compensate for a phase shift of a light beam having a predetermined wavelength, and can be used as a quarter-wave plate or a half-wave plate. . At a wavelength of 550 nm, the retardation value of the quarter-wave plate is about 110 to 160 nm (for example, 125 to 150 nm), and the retardation value of the half-wave plate is about 225 to 325 nm (for example, 250 to 300 nm). is there.

  The retardation film of the present invention is excellent in various film properties. For example, the total light transmittance of the retardation film of the present invention is 80% or more (for example, 83 to 99%), preferably 85% or more ( For example, it may be 87 to 98%), more preferably 90% or more (for example, 91 to 97%). The haze (total haze) of the retardation film of the present invention is 3% or less (for example, 0 to 2.5%), preferably 2% or less (for example, 0.1 to 1.8%), and more preferably. May be 1.5% or less (for example, 0.3 to 1.4%). In the retardation film of the present invention, in particular, even when composed of a plurality of modified glucan derivatives, surface roughness does not occur and transparency is not impaired.

[Method for producing retardation film]
The retardation film may be produced by forming a film or a sheet by a conventional method and without stretching (or orientation treatment) the obtained film or sheet, or may be produced by stretching (or orientation treatment). Good. For film molding, a melt molding method (melt film forming method) such as extrusion molding or blow molding may be used, or a cast molding method (cast film forming method) may be used. For film forming, a casting method is usually used. In the melt molding method, the modified glucan derivative alone or the composition containing the modified glucan derivative is melted using an extruder, extruded into a film form from a die slit, and cooled to prepare a film or sheet. A retardation film can be obtained without stretching (or orientation treatment) or stretching the film or sheet. In the melt molding method, extrusion molding is often performed using a T die. In the melt film-forming method, the film or sheet can be oriented by taking the molten film or sheet from the die. In the present specification, such an orientation can also be included in the concept of stretching.

  In the casting method, a film or sheet is prepared by casting a dope containing the modified glucan derivative, and a retardation film is obtained without stretching (or orientation treatment) or stretching the film or sheet. be able to. More specifically, the dope can be composed of the modified glucan derivative and a solvent in which the modified glucan derivative is soluble. Examples of the solvent include the above exemplified solvents (halogenated hydrocarbons such as methylene chloride and trichlorethylene, In addition to hydrocarbons, ketones, esters, ethers, etc.), alcohols (methanol, ethanol, isopropanol, etc.) can also be used. The concentration of the modified glucan derivative in the dope may be, for example, about 5 to 30% by weight, preferably about 10 to 25% by weight. The dope is cast on a peelable support (such as a metal drum) having a smooth surface, the solvent in the coating film of the dope is at least partially removed, and the solvent is contained by peeling from the support. A good film or sheet can be obtained. In the casting method, the film or sheet is stretched after the solvent is removed from the film or sheet.

  Cellulose acylates such as cellulose acetate and cellulose acetate propionate have different solvent solubility depending on the degree of substitution, and due to the affinity problem between the two components, a thick solution is produced during the solvent drying process of cast film formation. In the process of becoming, concentration fluctuations occur, the blended two components are likely to cause phase separation, and surface roughness occurs. However, the modified glucan derivative has a higher solubility in a solvent than the glucan derivative due to the graft-polymerized hydroxy acid component (or graft chain), so the difference in solubility between the components is reduced. Since the component (or graft chain) exhibits the effect of a compatibilizing agent that improves the affinity between the two components, it is difficult to cause concentration fluctuations, and a film having no surface roughness can be obtained.

  The stretching operation of the film or sheet may be, for example, stretched in the machine direction or the longitudinal direction (MD direction), may be stretched in the width direction (TD direction), or may be stretched in the MD direction and TD direction. . Stretching can be performed at a temperature equal to or higher than the glass transition temperature of the modified glucan derivative, and can usually be performed at a temperature equal to or lower than a predetermined temperature (glass transition temperature + 10 ° C.).

  The retardation film of the present invention is suitable for compensating for the retardation of light, and can be used in various optical devices as an optical element (such as an optical compensation film or an antireflection film). In particular, since a phase shift occurs due to transmission of liquid crystal or a polarizing plate, it is useful as an optical compensation film such as a retardation film in a liquid crystal display device. More specifically, a retardation film and a polarizing plate (or a polarizing film or a polarizer) may be laminated to form a circularly polarizing plate or an elliptically polarizing plate. In addition, a circularly-polarizing plate can be comprised by lamination | stacking with a quarter wavelength plate and a polarizing plate, and an elliptical polarizing plate can be comprised with lamination | stacking with a half-wave plate and a polarizing plate. The retardation film may be laminated on at least one surface of the polarizing plate (or polarizing film), or may be laminated on both surfaces of the polarizing plate. In such a laminated film, since the retardation film is composed of a glucan derivative, the retardation film can also function as a protective film for the polarizing plate. Therefore, the retardation film of the present invention is also useful as a protective film such as a polarizing plate protective film.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

  In the examples, various physical properties were measured as follows.

(Acetic acid average substitution degree of cellulose acetate, substituent distribution measurement of residual hydroxyl group)
Measurement of the average degree of substitution of cellulose acetate and the distribution of substituents of the remaining hydroxyl groups were carried out by propionylating the cellulose acetate to be analyzed and measuring the distribution of the substituted propionyl groups by NMR. Specifically, it is as follows.

(Propionylation)
0.4 g of cellulose acetate dried in a dryer at 80 ° C. for 24 hours was measured in a 50 ml eggplant type flask. Then, 8 ml of dichloromethane was added and mixed with stirring until uniform for about 1 hour. After confirming homogeneity, add 8 ml of pyridine, 8 ml of propionic anhydride in large excess to propionylation, 40 mg of dimethylaminopyridine, attach a condenser, and stir in an oil bath at 100 ° C. The reaction was carried out for 1 hour. After completion of the reaction, the reaction solution was added dropwise to 300 ml of methanol with stirring to obtain white fully substituted propionylated cellulose acetate. Then, the substituent distribution and the acetyl average substitution degree of each remaining hydroxyl group were determined from the peak area of the propionyl group substituted with the remaining hydroxyl groups at positions 2, 3 and 6 by ¹ H-NMR. The NMR measurement conditions are as follows.

Solvent: Deuterated chloroform Temperature: 40 ° C
Magnetic field strength: 500 MHz
Integration count: 16 times.

FIG. 1 is an example of a ¹ H-NMR spectrum of propionylated raw material cellulose acetate. In the figure, the unit of the horizontal axis is ppm, and the peak A (5-fold line) observed at 1.1 ppm is derived from the methyl group of propionic acid substituted at the 2nd and 3rd positions (2nd and 3rd positions). is there. Further, the methyl group of propionic acid substituted at the 6-position is observed as a peak B at 1.2 ppm in the vicinity of the peak A. Furthermore, a proton derived from a glucose unit is observed as a peak C at 3.4 to 5.2 ppm. The residual hydroxyl group substituent distribution and the acetic acid average substitution degree were calculated from these three peak areas.

That is,
2- and 3-position residual hydroxyl groups = (peak A area / 3) / (peak C area / 7)
Residual hydroxyl group at 6-position = (peak B area / 3) / (peak C area / 7)
Acetic acid average substitution degree = 3- (2,3-position residual hydroxyl group)-(6-position residual hydroxyl group)
I asked more.

(Measurement of primary structure of graft)
After purifying the obtained graft product, the molar fraction of each component from the peak area derived from the cellulose acetate and ε-caprolactone graft copolymer by a nuclear magnetic resonance apparatus (JNM A500, manufactured by JEOL Ltd.). The average number of moles of ε-caprolactone grafted on cellulose acetate (MS), the average degree of substitution of grafted ε-caprolactone (DS), and the average degree of polymerization of grafted ε-caprolactone (DPn) were determined. The NMR measurement conditions are as follows.

Solvent: dimethyl sulfoxide-d6
Temperature: 60 ° C
Magnetic field strength: 500 MHz
Integration count: 16 times.

(Haze)
The film was allowed to stand in a constant temperature and humidity room at 23 ° C. and 50% relative humidity for 48 hours, and in the same environment, using a turbidimeter (Nippon Denshoku Industries Co., Ltd., “NDH5000W”) according to JIS K7136. The haze was measured.

(Total light transmittance)
The film (unstretched film) was left in a constant temperature and humidity room at 23 ° C. and a relative humidity of 50% for 48 hours, and using a turbidimeter (Nippon Denshoku Industries Co., Ltd., “NDH5000W”), JIS K7361-1 The total light transmittance was measured according to the above.

[Reference Example 1]
(Synthesis of graft body)
Cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., L-20, average substitution degree 2.44, 2, 3rd position (2nd and 3rd positions, the same shall apply hereinafter) residual hydroxyl group in a reactor equipped with a stirrer and an irrigation type stirring blade 70 parts by weight of 0.31, 6-position residual hydroxyl group 0.25) was added, and dried under reduced pressure at 110 ° C. for 4 hours at 4 Torr. Thereafter, the system was purged with dry nitrogen, a reflux condenser was attached, 30 parts by weight of ε-caprolactone which had been dried and distilled beforehand, 2.7 parts by weight of dipropylphenylcarbodiimide (DPC), cyclohexanone which had been dried and distilled beforehand ( ANON) 67 parts by weight was added and heated to 150 ° C. and stirred to uniformly dissolve the cellulose acetate. The water content in this reaction system was 0.03% by weight. To this mixed solution, 0.25 part by weight of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction mixture was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts by weight of the reaction solution was dissolved in 90 parts by weight of dichloromethane, and then slowly dropped into 900 parts by weight of a large excess of methanol, and the precipitated precipitate (graft body) was separated by filtration. The caprolactone homopolymer was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-caprolactone graft copolymer) which (epsilon) -caprolactone grafted to the cellulose acetate.

And the primary structure of the graft body obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles (MS) of ε-caprolactone grafted per mole of glucose unit was 0.82, the average degree of substitution (DS) of the graft chain (grafted caprolactone) was 0.092, and ε- of the graft chain. The average degree of polymerization (DPn) of caprolactone was 8.9.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. The film was then supported on a stainless steel frame and dried for 30 minutes with a hot air dryer at 100 ° C. to obtain a film with a thickness of 105 μm. When the transparency of the film was measured, the total light transmittance was 92.2%, the total haze was 0.5%, and the external haze was 0.2%.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film is stretched in the width direction at 145 ° C. The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film was 100 μm, and the wavelength dispersion characteristic of retardation was measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. However, Re (550 nm) = 201 nm, Re (450 nm) / Re (550 nm) = 0.92, and Re (630 nm) / Re (550 nm) = 1.03.

[Example 1]
(Synthesis of cellulose acetate)
698 parts by weight of acetic acid was uniformly sprayed on 1520 parts by weight of the pulverized pulp containing 8.2% by weight of water, and after stirring, the mixture was allowed to stand at room temperature for 90 minutes. The above-mentioned acetic acid impregnated pulp was put into a mixed solution of 3930.6 parts by weight of acetic anhydride, 5755 parts by weight of acetic acid and 115.4 parts by weight of 98% sulfuric acid cooled to about -10 ° C and mixed. By external cooling and external heating, the reaction temperature was linearly increased from 0 ° C. at the start of the reaction to 37 ° C. after 70 minutes, and further maintained at 37 ° C. for 80 minutes to synthesize cellulose acetate.

  To the synthesized cellulose acetate solution, 383.7 parts by weight of a 30% aqueous acetic acid solution was added and maintained at a reaction temperature of 47 ° C. for 130 minutes. The amount of water relative to acetic acid was 6.0 mol%. Thereafter, 297 g of an aqueous solution of magnesium acetate tetrahydrate was added to stop the reaction.

  The resulting solution was poured into 30 liters of 10% aqueous acetic acid with vigorous stirring to form a precipitate. The precipitate was separated by filtration, washed with running water, washed with hot water, further washed with running water and centrifuged, and dried at 50 ° C.

  The average cellulose acetate substitution degree of the obtained raw material cellulose acetate was 2.78, 2,3-position residual hydroxyl group 0.11, and 6-position residual hydroxyl group 0.11.

(Synthesis of graft body)
70 parts by weight of cellulose acetate (average substitution degree 2.78, 2,3-position residual hydroxyl group 0.11, 6-position residual hydroxyl group 0.11) obtained in a reactor equipped with a stirrer and an anchor type stirring blade were added, The film was dried under reduced pressure at 110 ° C. for 4 hours at 4 Torr. Thereafter, the system was purged with dry nitrogen, a reflux condenser was attached, 30 parts by weight of ε-caprolactone which had been dried and distilled beforehand, 2.7 parts by weight of dipropylphenylcarbodiimide (DPC), cyclohexanone which had been dried and distilled beforehand ( ANON) 67 parts by weight was added and heated to 150 ° C. and stirred to uniformly dissolve the cellulose acetate. The water content in this reaction system was 0.03% by weight. To this mixed solution, 0.25 part by weight of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction mixture was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts by weight of the reaction solution was dissolved in 90 parts by weight of dichloromethane, and then slowly dropped into 900 parts by weight of a large excess of methanol, and the precipitated precipitate (graft body) was separated by filtration. The caprolactone homopolymer was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-caprolactone graft copolymer) which (epsilon) -caprolactone grafted to the cellulose acetate.

And the primary structure of the graft body obtained by < ¹ > H-NMR was analyzed. As a result, the average mole number (MS) of ε-caprolactone grafted per mole of glucose unit was 0.67, the average degree of substitution (DS) of the graft chain (grafted caprolactone) was 0.062, and ε- of the graft chain. The average degree of polymerization (DPn) of caprolactone was 11.0.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 103 μm. When the transparency of the film was measured, the total light transmittance was 92.2%, the total haze was 0.5%, and the external haze was 0.2%.

  The unstretched film was measured in the width direction at 165 ° C. using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film is 97 μm, and the wavelength dispersion characteristic of retardation is measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. Re (550 nm) = 35 nm, Re (450 nm) / Re (550 nm) = 0.37, and Re (630 nm) / Re (550 nm) = 1.30.

[Example 2] (Synthesis of cellulose acetate)
Cellulose acetate was synthesized according to the method described in JP-A-9-286801. That is, 7.8 parts by weight of sulfuric acid, 260 parts by weight of acetic anhydride and 400 parts by weight of acetic acid were added to 100 parts by weight of cellulose, and acetylation was performed at 40 ° C. for 40 minutes. Thereafter, the reaction product was washed with a large excess of water, dried, and dissolved in 1500 parts by weight of DMSO (dimethyl sulfoxide). A mixture of 27 parts by weight of hydrazine monohydrate and 100 parts by weight of DMSO was added thereto, and partial hydrolysis was performed at 50 ° C. for 5 hours. Thereafter, the reaction product was precipitated with a large excess of water, washed and dried.

  Next, 100 parts by weight of the dried reaction product was dissolved in 3000 parts by weight of pyridine at 100 ° C. Trityl chloride was added to this by adding 8.5 parts by weight of trityl chloride, adjusting the temperature to 90 ° C., and stirring for 25 hours. Thereafter, 90 parts by weight of 4-dimethylaminopyridine and 50 parts by weight of acetic anhydride were further added, and the mixture was stirred at 60 ° C. for 20 hours for acetylation. Thereafter, the reaction product was precipitated with a large excess of water, and then washed with 1000 parts by weight of methanol three times. The reaction product was dried and then dissolved in 3000 parts by weight of chloroform. To this, 40 parts by weight of 30% by weight hydrobromic acid in acetic acid was added and stirred at 25 ° C. for 5 minutes to perform detritylation. The reaction product was precipitated with a large excess of water, washed with 1000 parts by weight of methanol three times, and dried to obtain cellulose acetate.

  Further, 100 parts by weight of the obtained cellulose acetate was dissolved in 500 parts by weight of methylene chloride. To this was added 1000 parts by weight of a 96% aqueous acetic acid solution, and the cellulose acetate was partially hydrolyzed with acetic acid and water at 65 ° C. for 45 minutes while removing methylene chloride under reduced pressure. The reaction was precipitated, washed and dried with a large excess of water.

  The average cellulose acetate substitution degree of the obtained raw material cellulose acetate was 2.72, the residual hydroxyl group at position 2,1, 0.11, and the residual hydroxyl group at position 6, 0.17.

(Synthesis of graft body)
70 parts by weight of cellulose acetate (average substitution degree 2.72, 2,3-position residual hydroxyl group 0.11, 6-position residual hydroxyl group 0.17) obtained in a reactor equipped with a stirrer and an irrigation type stirring blade were added, The film was dried under reduced pressure at 110 ° C. for 4 hours at 4 Torr. Thereafter, the system was purged with dry nitrogen, a reflux condenser was attached, 30 parts by weight of ε-caprolactone which had been dried and distilled beforehand, 2.7 parts by weight of dipropylphenylcarbodiimide (DPC), cyclohexanone which had been dried and distilled beforehand ( ANON) 67 parts by weight was added and heated to 150 ° C. and stirred to uniformly dissolve the cellulose acetate. The water content in this reaction system was 0.03% by weight. To this mixed solution, 0.25 part by weight of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction mixture was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts by weight of the reaction solution was dissolved in 90 parts by weight of dichloromethane, and then slowly dropped into 900 parts by weight of a large excess of methanol, and the precipitated precipitate (graft body) was separated by filtration. The caprolactone homopolymer was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-caprolactone graft copolymer) which (epsilon) -caprolactone grafted to the cellulose acetate.

And the primary structure of the graft body obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles (MS) of ε-caprolactone grafted per mole of glucose unit was 0.76, the average degree of substitution (DS) of the graft chain (grafted caprolactone) was 0.061, and ε- of the graft chain. The average degree of polymerization (DPn) of caprolactone was 12.5.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 106 μm. When the transparency of the film was measured, the total light transmittance was 92.2%, the total haze was 0.6%, and the external haze was 0.2%.

  The unstretched film was measured in the width direction at 165 ° C. using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film is 98 μm, and the wavelength dispersion characteristic of retardation is measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. Re (550 nm) = 42 nm, Re (450 nm) / Re (550 nm) = 0.53, and Re (630 nm) / Re (550 nm) = 1.22.

[Example 3]
(Create film)
Put 7.5 parts by weight of the graft obtained in Reference Example 1, 7.5 parts by weight of the graft obtained in Example 1, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol in a sealed container, and slowly mix the mixture. Dissolved over 24 hours with stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 110 μm. When the transparency of the film was measured, the transmittance was 92.6%, the total haze was 0.8, and the external haze was 0.6.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film is stretched in the width direction at 155 ° C. The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film is 106 μm, and the wavelength dispersion characteristic of retardation is measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. Re (550 nm) = 125 nm, Re (450 nm) / Re (550 nm) = 0.85, and Re (630 nm) / Re (550 nm) = 1.07.

[Example 4]
(Create film)
155 using the unstretched film obtained in Example 3 using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 2.0 times (uniaxial stretching at the free end) at a rate of 100% / min in the width direction at ° C. When the thickness of the obtained stretched film was 102 μm and the wavelength dispersion characteristic of retardation was measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity, Re (550 nm) = 137 nm, Re (450 nm) / Re (550 nm) = 0.84, and Re (630 nm) / Re (550 nm) = 1.08.

[Example 5]
(Create film)
6 parts by weight of the grafted body obtained in Reference Example 1, 9 parts by weight of the grafted body obtained in Example 1, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was stirred while slowly stirring. Dissolved over time. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 108 μm. When the transparency of the film was measured, the total light transmittance was 92.7%, the total haze was 1.0%, and the external haze was 0.6%.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film is stretched in the width direction at 155 ° C. The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film was 103 μm, and the wavelength dispersion characteristic of retardation was measured with an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) at 23 ° C. and 50% humidity. Re (550 nm) = 100 nm, Re (450 nm) / Re (550 nm) = 0.81, and Re (630 nm) / Re (550 nm) = 1.08.

[Example 6]
(Create film)
Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film obtained in Example 5 was 155. The film was stretched 2.0 times (uniaxial stretching at the free end) at a rate of 100% / min in the width direction at ° C. The thickness of the obtained stretched film is 99 μm, and the wavelength dispersion characteristic of retardation is measured with an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. Re (550 nm) = 122 nm, Re (450 nm) / Re (550 nm) = 0.79, Re (630 nm) / Re (550 nm) = 1.08.

[Example 7]
(Create film)
9.75 parts by weight of the graft body obtained in Reference Example 1, 5.25 parts by weight of the graft body obtained in Example 1, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol are placed in a sealed container, and the mixture is slowly added. Dissolved over 24 hours with stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 103 μm. When the transparency of the film was measured, the total light transmittance was 92.6%, the total haze was 1.2%, and the external haze was 0.6%.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film is stretched in the width direction at 145 ° C. The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film is 94 μm, and the wavelength dispersion characteristic of retardation is measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. Re (550 nm) = 145 nm, Re (450 nm) / Re (550 nm) = 0.87, and Re (630 nm) / Re (550 nm) = 1.06.

[Reference Example 2]
(Create film)
Cellulose acetate obtained in Example 1 (average substitution degree 2.78, 2,3-position residual hydroxyl group 0.11, 6-position residual hydroxyl group 0.11) 7.5 parts by weight, cellulose acetate (Daicel Chemical Industries, Ltd.) L-20, average substitution degree 2.44, 2,3-position residual hydroxyl group 0.31, 6-position residual hydroxyl group 0.25) 7.5 parts by weight, methylene chloride 78 parts by weight, and methanol 15 parts by weight Place in a container and dissolve the mixture over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 98 μm. When the transparency of the film was measured, the total light transmittance was 92.7%, the total haze was 2.7%, and the external haze was 1.6%. It was confirmed that the surface of the film was clearly rough and cloudy visually.

  The unstretched film was measured in the width direction at 190 ° C. using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. When the thickness of the obtained stretched film was 92 μm and the wavelength dispersion characteristic of retardation was measured with an automatic birefringence meter (KOBRA-WPR manufactured by Oji Scientific Instruments) in an atmosphere of 23 ° C. and 50% humidity, Re ( 550 nm) = 148 nm, Re (450 nm) / Re (550 nm) = 0.85, and Re (630 nm) / Re (550 nm) = 1.06.

[Reference Example 3]
(Create film)
6 parts by weight of cellulose acetate (manufactured by Daicel Chemical Industries, L-20, average substitution degree 2.44, 2,3-position residual hydroxyl group 0.31, 6-position residual hydroxyl group 0.25), obtained in Example 1 9 parts by weight of the graft, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 107 μm. When the transparency of the film was measured, the total light transmittance was 92.1%, the total haze was 5.4%, and the external haze was 1.8%. It was confirmed that the surface of the film was clearly rough and cloudy visually.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film is stretched in the width direction at 160 ° C. The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. When the thickness of the obtained stretched film was 100 μm and the wavelength dispersion characteristic of retardation was measured with an automatic birefringence meter (KOBRA-WPR manufactured by Oji Scientific Instruments) in an atmosphere of 23 ° C. and 50% humidity, Re ( 550 nm) = 67 nm, Re (450 nm) / Re (550 nm) = 0.71, and Re (630 nm) / Re (550 nm) = 1.12.

[Reference Example 4]
(Create film)
6. 7.5 parts by weight of cellulose acetate propionate (Eastman Chemical Co., CAP482-20, acetic acid average substitution degree 0.1, propionic acid average substitution degree 2.6), graft body obtained in Example 1 5 parts by weight, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 106 μm. When the transparency of the film was measured, the total light transmittance was 90.8%, the total haze was 23.2%, and the external haze was 17.6%. It was confirmed that the surface of the film was clearly rough and cloudy visually.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film is stretched in the width direction at 160 ° C. The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. When the thickness of the obtained stretched film was 100 μm and the wavelength dispersion characteristic of retardation was measured with an automatic birefringence meter (KOBRA-WPR manufactured by Oji Scientific Instruments) in an atmosphere of 23 ° C. and 50% humidity, Re ( 550 nm) = 48 nm, Re (450 nm) / Re (550 nm) = 0.73, and Re (630 nm) / Re (550 nm) = 1.12.

[Example 8] (Synthesis of cellulose acetate)
To 100 parts by weight of cellulose, 7.8 parts by weight of sulfuric acid, 260 parts by weight of acetic anhydride cooled to −10 ° C. and 400 parts by weight of acetic acid were added, and acetylation was performed at 40 ° C. for 40 minutes. Thereafter, the reaction product was precipitated and dried with a large excess of water, and dissolved in 1500 parts by weight of DMSO. A mixture of 27 parts by weight of hydrazine monohydrate and 100 parts by weight of dimethyl sulfoxide (DMSO) was added thereto, and partial hydrolysis was performed at 50 ° C. for 5 hours. Thereafter, the reaction product was precipitated, washed with a large excess of water, and dried.

  Next, 100 parts by weight of the dried reaction product was dissolved in 3000 parts by weight of pyridine at 100 ° C. To this was added 8.5 parts by weight of trityl chloride, and the temperature was adjusted to 90 ° C., followed by tritylation with stirring for 25 hours. Thereafter, 90 parts by weight of 4-dimethylaminopyridine and 50 parts by weight of acetic anhydride were further added, and acetylation was performed with stirring at 60 ° C. for 20 hours. Thereafter, the reaction product was precipitated with a large excess of water, and then washed with 1000 parts by weight of methanol three times. The reaction product was dried and then dissolved in 3000 parts by weight of chloroform. To this, 40 parts by weight of 30% by weight hydrobromic acid in acetic acid was added and stirred at 25 ° C. for 5 minutes to perform detritylation. The reaction product was precipitated with a large excess of water, washed with 1000 parts by weight of methanol three times, and dried to obtain cellulose acetate.

  Further, 100 parts by weight of the obtained cellulose acetate was dissolved in 500 parts by weight of methylene chloride. To this was added 1000 parts by weight of a 96% aqueous acetic acid solution, and the cellulose acetate was partially hydrolyzed with acetic acid and water at 65 ° C. for 115 minutes while removing methylene chloride under reduced pressure. The reaction was precipitated, washed and dried with a large excess of water. The average cellulose acetate substitution degree of the raw material cellulose acetate obtained was 2.62, 0.13 hydroxyl group at 2,3 position, and 0.21 hydroxyl group at 6 position.

(Synthesis of graft body)
70 parts by weight of cellulose acetate (average substitution degree 2.62; 2,3-position residual hydroxyl group 0.17, 6-position residual hydroxyl group 0.21) obtained in a reactor equipped with a stirrer and an anchor type stirring blade were added, The film was dried under reduced pressure at 110 ° C. for 4 hours at 4 Torr. Thereafter, the system was purged with dry nitrogen, a reflux condenser was attached, 30 parts by weight of ε-caprolactone which had been dried and distilled beforehand, 2.7 parts by weight of dipropylphenylcarbodiimide (DPC), cyclohexanone which had been dried and distilled beforehand ( ANON) 67 parts by weight was added and heated to 150 ° C. and stirred to uniformly dissolve the cellulose acetate. The water content in this reaction system was 0.03% by weight. To this mixed solution, 0.25 part by weight of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction mixture was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts by weight of the reaction solution was dissolved in 90 parts by weight of dichloromethane, and then slowly dropped into 900 parts by weight of a large excess of methanol, and the precipitated precipitate (graft body) was separated by filtration. The caprolactone homopolymer was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-caprolactone graft copolymer) which (epsilon) -caprolactone grafted to the cellulose acetate.

And the primary structure of the graft body obtained by < ¹ > H-NMR was analyzed. As a result, the average mole number (MS) of ε-caprolactone grafted per mole of glucose unit was 0.69, the average degree of substitution (DS) of the graft chain (grafted caprolactone) was 0.092, and ε- of the graft chain. The average degree of polymerization (DPn) of caprolactone was 7.5.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

  The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a film thickness of 145 μm. When the transparency of the film was measured, the total light transmittance was 92.6%, the total haze was 0.4%, and the external haze was 0.2%.

  The unstretched film was measured in the width direction at 165 ° C. using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film is 138 μm, and the wavelength dispersion characteristic of retardation is measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments Co., Ltd., KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. Re (550 nm) = 137 nm, Re (450 nm) / Re (550 nm) = 0.81, and Re (630 nm) / Re (550 nm) = 1.08.

[Example 9]
(Synthesis of cellulose acetate)
In a reactor equipped with a stirrer, an irrigation type stirring blade, and a cooling tube, cellulose acetate having a water content of 0.1% by weight preliminarily dried at 90 ° C. for 24 hours (manufactured by Daicel Chemical Industries, Ltd., L-20, Average substitution degree 2.44, 2,3-position residual hydroxyl group 0.31, 6-position residual hydroxyl group 0.25) 70 parts by weight and pyridine 740 parts by weight were added under stirring in a dry nitrogen atmosphere at 100 ° C. for 2 hours. Homogenization was performed. After confirming homogeneity, 4 parts by weight of 4-dimethylaminopyridine and 5.8 parts by weight of acetic anhydride were added, and the mixture was reacted at 100 ° C. for 1 hour with stirring. Thereafter, the reaction mixture was cooled to room temperature to obtain a reaction solution. Furthermore, 10 parts by weight of the reaction solution was dissolved in 90 parts by weight of dichloromethane, and then slowly dropped into 900 parts by weight of a large excess of methanol to obtain raw material cellulose acetate.

  The obtained raw material cellulose acetate had an average degree of substitution of acetic acid of 2.58, a residual hydroxyl group at 2- and 3-positions of 0.26, and a residual hydroxyl group of 6-position of 0.16.

(Synthesis of graft body)
70 parts by weight of cellulose acetate (average substitution degree 2.58, 2,3-position residual hydroxyl group 0.26, 6-position residual hydroxyl group 0.16) obtained in a reactor equipped with a stirrer and an irrigation type stirring blade were added, The film was dried under reduced pressure at 110 ° C. for 4 hours at 4 Torr. Thereafter, the system was purged with dry nitrogen, a reflux condenser was attached, 30 parts by weight of ε-caprolactone which had been dried and distilled beforehand, 2.7 parts by weight of dipropylphenylcarbodiimide (DPC), cyclohexanone which had been dried and distilled beforehand ( ANON) 67 parts by weight was added and heated to 150 ° C. and stirred to uniformly dissolve the cellulose acetate. The water content in this reaction system was 0.03% by weight. To this mixed solution, 0.25 part by weight of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction mixture was cooled to room temperature to terminate the reaction and obtain a reaction product. Furthermore, 10 parts by weight of the reaction solution was dissolved in 90 parts by weight of dichloromethane, and then slowly dropped into 900 parts by weight of a large excess of methanol, and the precipitated precipitate (graft body) was separated by filtration. The caprolactone homopolymer was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-caprolactone graft copolymer) which (epsilon) -caprolactone grafted to the cellulose acetate.

And the primary structure of the graft body obtained by < ¹ > H-NMR was analyzed. As a result, the average number of moles (MS) of ε-caprolactone grafted per mole of glucose unit was 0.82, the average degree of substitution (DS) of the graft chain (grafted caprolactone) was 0.071, and ε- of the graft chain. The average degree of polymerization (DPn) of caprolactone was 11.5.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 15 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. After the dope was filtered under pressure, the dope was removed by leaving still for 24 hours.

The dope was cast on a glass plate at a dope temperature of 20 ° C. using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After the leveling, the film was peeled off from the glass plate after drying for 30 minutes with a hot air dryer at 40 ° C. Next, the film was supported on a stainless steel frame and dried with a hot air dryer at 100 ° C. for 30 minutes to obtain a film having a thickness of 115 μm. When the transparency of the film was measured, the total light transmittance was 92.7%, the total haze was 0.5%, and the external haze was 0.2%.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the unstretched film is stretched in the width direction at 145 ° C. The film was stretched 1.5 times (free end uniaxial stretching) at a rate of 100% / min. The thickness of the obtained stretched film is 110 μm, and the wavelength dispersion characteristic of retardation is measured with an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WPR) in an atmosphere of 23 ° C. and 50% humidity. Re (550 nm) = 137 nm, Re (450 nm) / Re (550 nm) = 0.88, and Re (630 nm) / Re (550 nm) = 1.05.

FIG. 1 is a ¹ H-NMR spectrum (unit: ppm on the horizontal axis) of propionylated raw material cellulose acetate.

Claims (9)

A retardation film composed of a hydroxy acid-modified glucan derivative in which a hydroxy acid component is graft-polymerized to a hydroxyl group of a glucan derivative, and satisfying the following formula in one film without lamination.
0.05 ≦ Re (450 nm) / Re (550 nm) ≦ 0.9
(In the formula, Re (450 nm) and Re (550 nm) indicate phase difference values at wavelengths of 450 nm and 550 nm, respectively.) The retardation film according to claim 1, wherein the hydroxy acid-modified glucan derivative is composed of a plurality of hydroxy acid-modified glucan derivatives and satisfies the following formula in one film without being laminated.
0.7 ≦ Re (450 nm) / Re (550 nm) ≦ 0.9
(In the formula, Re (450 nm) and Re (550 nm) are the same as above.)   A plurality of hydroxy acid-modified glucan derivatives are (A) a hydroxy acid-modified glucan derivative in which the glucan derivative is a cellulose acylate having an acyl group average substitution degree of 2.7 to 2.95, and (B) the glucan derivative is an acyl group. The retardation film according to claim 2, comprising a hydroxy acid-modified glucan derivative having an average substitution degree of 2.0 to 2.55 cellulose acylate.   The retardation film according to claim 3, wherein the ratio of the modified glucan derivative (A) to the modified glucan derivative (B) is the former / the latter (weight ratio) = 90/10 to 10/90. The glucan derivative is cellulose C _2-4 acylate, and the hydroxy acid component is at least one selected from hydroxy C _2-10 alkane carboxylic acid, C _4-10 lactone and C _4-10 cyclic diester, The retardation film according to any one of claims 1 to 4, wherein the hydroxy acid component is grafted at an average ratio of 0.1 to 4 mol in terms of hydroxy acid with respect to 1 mol of glucose unit. The retardation film according to claim 1, wherein the glucan derivative is cellulose acetate and the hydroxy acid component is C _4-10 lactone.   The retardation film according to claim 1, having a total light transmittance of 85% or more and a haze of 3% or less.   The retardation film according to claim 1, which is a quarter-wave plate or a half-wave plate.   A circularly or elliptically polarizing plate in which the retardation film according to claim 1 and a polarizing plate are laminated.

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