JP2007254707A - Modified glucan derivative for optical use and molded article for optical use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an α-hydroxy acid-modified glucan derivative (e.g. a modified cellulose acylate, etc.) capable of suitably being utilized for an optical use such as an optical film, etc., and having a high practicality. <P>SOLUTION: This modified glucan derivative having a glucan derivative (cellulose acetate, etc.) and a hydroxy acid-modified glucan derivative having a graft chain formed by graft-polymerizing the hydroxy acid component constituted by the α-hydroxy acid component (lactide, etc.) with the hydroxy group of the glucan derivative is provided by setting in average 0.1 to 5 mol ratio of the graft polymerized hydroxy acid component based on 1 mol glucose unit constituting the glucan derivative. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydroxy acid-modified glucan derivative (for example, hydroxy acid-modified cellulose acylate) useful as an optical application (for example, an optical film), and an optical molded body (for example, an optical film) formed from the modified glucan derivative. Etc.).

  Glucan having glucose as a structural unit, such as cellulose, starch (or amylose), and dextran, does not have thermoplasticity, and cannot be used as it is as plastic (thermoplastic plastic). Therefore, such a glucan (particularly cellulose) is utilized as a thermoplastic plastic by being acylated (acetylated or the like) for thermoplasticization.

  Among the glucans, in particular, cellulose is acylated and used for various uses as cellulose acylate (particularly, cellulose acetate). In particular, since cellulose ester is excellent in optical properties, it is used for optical applications such as a support for a photographic photosensitive material, a polarizing plate protective film for a liquid crystal display device, a retardation film, and a color filter. For example, cellulose diacetate having an average degree of substitution of about 2.4 to 2.5 is used for thermoforming in a form containing a plasticizer from the viewpoint of thermoplasticity. However, since such cellulose diacetate has a hydroxyl group, there are problems such as high hygroscopicity and reduced dimensional stability. Cellulose triacetate (average substitution degree of about 2.8 to 2.9) is processed into a film, fiber, or the like by a molding method using a limited solvent such as methylene chloride because of poor thermoformability. This is the actual situation. That is, although cellulose triacetate has a glass transition temperature Tg of about 120 ° C., the melting point Tm is not clear, and when heated, thermal decomposition precedes melting. Therefore, the cellulose triacetate film is unsuitable for thermoforming as described above and cannot be obtained by the melt film formation method [Cellulose Commun Vol.5, No.2 (1998) (Non-patent Document 1)] and stretched. Difficult to do. On the other hand, cellulose mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate can improve hot meltability and thermoformability (stretchability) as compared with cellulose triacetate.

  A technique for improving solubility, heat melting property and melt moldability by modifying cellulose acylate has also been reported. For example, JP-A-60-188401 (Patent Document 1) discloses that 0.5 to 4.0 moles of cyclic ester per anhydroglucose unit of a fatty acid cellulose ester (such as cellulose acetate) having a free hydroxyl group. A fatty acid cellulose ester-based thermoplastic molding material obtained by adding ε-caprolactone or the like is disclosed. This document also describes that internal plasticization can be performed by injection molding, extrusion molding, or the like without adding a large amount of plasticizer, and can be used for molded articles such as sheets and films. This document describes that in the examples, an ε-caprolactone-added cellulose acetate having a maximum degree of acetyl substitution of 2.25 was obtained. Such cellulose acetate having a low degree of acetyl substitution is poor in moisture resistance and inferior to that having a high degree of acetyl substitution in terms of optical properties, and as described above, usually for optical applications such as optical films. Cellulose acetate having a relatively high degree of acetyl substitution such as cellulose triacetate is used. In addition, in the method of this document, the acyl substitution of the cyclic ester-added fatty acid cellulose ester as a product may be caused by hydrolysis of the acyl group in the cyclic ester addition reaction. It is difficult to obtain a cyclic ester adduct having a desired acyl substitution degree, and there is a possibility that the optical properties may be lowered as described above due to the reduction of the acyl substitution degree.

  JP-A-6-287279 (Patent Document 2) discloses a lactide system in which lactide (A) and cellulose ester or cellulose ether (B) are subjected to ring-opening graft copolymerization in the presence of an esterification catalyst (C). A method for producing a graft copolymer is disclosed. In this document, lactide-based graft copolymers have transparency, decomposability, and thermoplastic properties, and are useful as film materials and molding resins, including lamination and ink resins. Is described.

  Cellulose esters modified with hydroxycarboxylic acids or cyclic esters (such as lactide and lactone) have higher thermoformability than cellulose acetate and the like, and thus may be applied to optical applications such as optical films. For example, JP-A-2001-281448 (Patent Document 3) discloses an optical element containing a copolymer of lactic acid and a (co) polymerizable polyfunctional compound other than lactic acid (Claim 1), other than lactic acid. The (co) polymerizable polyfunctional compound is composed of a hydroxycarboxylic acid other than lactic acid, a cyclic ester, a polyvalent carboxylic acid, an anhydride of a polyvalent carboxylic acid, a polyhydric alcohol, a polysaccharide, and an aminocarboxylic acid. An optical element that is at least one selected from the above (Claim 4), and an optical element that is at least one selected from the group consisting of cellulose and chemically modified cellulose (Claim 9) are disclosed. In addition, this document only describes polysaccharides such as cellulose as an example of a copolymerizable polyfunctional compound, and does not describe details of the chemically modified cellulose.

  JP-A-2005-300978 (Patent Document 4) is composed of a cellulose ester film obtained by stretching and orienting a cellulose ester resin sheet formed by a melt casting film forming method in the width direction, and has a thickness of 20 to 100 μm. A retardation film having an in-plane retardation (Ro) of 20 to 100 nm and a thickness direction retardation (Rt) of 90 to 200 nm is disclosed. In this document, cellulose acylates such as cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, and aliphatic polyester graft side chains (graft polymer side chains) are used as cellulose esters. The cellulose acetate etc. which have are illustrated. In this document, (i) cellulose acetate having an aliphatic polyester graft side chain includes cellulose acetate having an aliphatic polyester graft side chain having lactic acid as a main repeating unit, and (ii) lactic acid is mainly used. The degree of acetyl substitution of cellulose acetate having an aliphatic polyester graft side chain as a repeating unit is preferably 2.5 to 3.0 per glucose unit, and (iii) the molecular weight of the aliphatic polyester graft side chain is 1000 It is described that it is preferable that it is -10000. Specifically, in Example 2, 100 parts by weight of cellulose acetate (acetyl substitution degree: 2.8, number average molecular weight 120,000) that had been vacuum-dried at 60 ° C. for 24 hours was reacted with 400 parts by weight of L-lactide. Finally, a flaky reaction product was obtained, a mixture containing this reaction product and an antioxidant was pelletized, a resin sheet was obtained, and further stretched to obtain a retardation film having a thickness of 100 μm. Are listed.

However, in the cellulose acetate having an aliphatic polyester graft chain described in this document, since the amount of lactic acid (polylactic acid or polylactide) substituted for the cellulose acetate is too large, the original properties of cellulose acetate are deteriorated. Further, since the amount of lactic acid to be grafted is too large, the glass transition temperature of the modified cellulose acetate is low and the heat resistance is not sufficient. Moreover, such cellulose acetate having a large graft amount of lactic acid not only tends to change its optical characteristics due to heat, but also may impair the excellent characteristics of cellulose acetate. For example, when the polymerization degree or molecular weight of the lactic acid graft chain increases, the graft chain portion exhibits crystallinity, and whitening and haze deterioration tend to occur. Thus, cellulose acetate having a graft chain that can withstand practical use has not been known so far for optical applications.
JP-A-60-188401 (Claims, lower right column on page 2) JP-A-6-287279 (claims, column of effect of invention) JP 2001-281448 A (Claims, paragraph number [0033]) JP-A-2005-300978 (Claims, paragraph numbers [0023] [0029] [0030] [0074] to [0076]) Cellulose Commun Vol.5, No.2 (1998)

  Therefore, the object of the present invention is to provide a highly practical modified glucan that can impart optical properties without degrading the original properties of a glucan derivative (such as cellulose acylate) even when modified with an α-hydroxy acid component such as lactide. It is an object to provide a derivative (for example, modified cellulose acylate) and an optical molded body (for example, an optical film) formed of the modified glucan derivative.

  Another object of the present invention is to provide a modified glucan derivative (for example, a modified cellulose acylate) that can impart excellent heat resistance and can be suitably used for optical applications such as an optical film, and an optical formed with the modified glucan derivative. The object is to provide a molded article (for example, an optical film).

  Still another object of the present invention is a modified glucan derivative having excellent optical properties and high practicality that can be suitably used even in applications requiring heat resistance, and optical molding formed with the modified glucan derivative. The object is to provide a body (eg, an optical film).

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that in a modified glucan derivative in which an α-hydroxy acid component (for example, lactic acid, lactide, etc.) is graft-polymerized to a glucan derivative (for example, cellulose acetate), The inventors have found that by setting the proportion of the hydroxy acid component substituted for the glucan derivative to a specific small proportion, optical characteristics can be imparted without impairing the excellent characteristics of the glucan derivative, and the present invention has been completed.

  That is, the optically modified glucan derivative of the present invention is a hydroxy acid-modified glucan derivative for use in optical applications. The glucan derivative (or glucan derivative skeleton) and the hydroxyl group of the glucan derivative have an α-hydroxy acid component. The hydroxy acid component composed of a graft chain formed by graft polymerization, and the ratio of the grafted hydroxy acid component is an average in terms of hydroxy acid with respect to 1 mol of glucose unit constituting the glucan derivative. 0.1 to 5 mol.

The glucan derivative may be a cellulose derivative, such as cellulose acylate (for example, cellulose C _2-4 acylate). In particular, the glucan derivative may be cellulose acylate (particularly cellulose acetate) having an average substitution degree of acetyl group of about 1.5 to 2.95.

  In the modified glucan derivative, the glucan derivative is cellulose acylate having an average substitution degree of acyl group of 2.6 or less, and the ratio of the graft-polymerized hydroxy acid component is 1 mol of glucose unit constituting the glucan derivative. On the other hand, the average may be 0.2-4 mol in terms of hydroxy acid.

The hydroxy acid component may be composed of at least one selected from α-hydroxy C _2-10 alkanecarboxylic acid and C _4-10 cyclic diester.

  The average degree of polymerization of the graft chain may be about 2 to 12 in terms of hydroxy acid. In particular, the graft chain may have an average degree of polymerization of 2 to 11 and an average molecular weight of 900 or less in terms of hydroxy acid. By using such a relatively low degree of polymerization as the graft chain, it is possible to modify the glucan derivative while efficiently maintaining the characteristics of the glucan derivative. In addition, by relatively reducing the degree of polymerization and the molecular weight of the graft chain, crystallization of the graft chain portion can be efficiently suppressed, and the glucan derivative can be efficiently modified without reducing whitening generation or transparency.

In a typical modified glucan derivative of the present invention, the glucan derivative is cellulose acylate having an average substitution degree of 2 to 2.95 (especially cellulose C _2-4 acylate such as cellulose acetate), and the hydroxy acid component is lactic acid and And / or at least composed of lactide, the ratio of the grafted hydroxy acid component is 0.2 to 4 moles on average in terms of hydroxy acid per mole of glucose units constituting the glucan derivative, and the average polymerization of graft chains Modified glucan derivatives having a degree of hydroxy acid conversion of 2.5 to 10.5 and an average molecular weight of the graft chain of 800 or less are included.

  The present invention also includes an optical molded body (particularly an optical film) formed from the modified glucan derivative.

  In the present specification, the “average degree of substitution” refers to a hydroxyl group that is derivatized (etherified, esterified, grafted, etc.) among the hydroxyl groups at the 2, 3 and 6 positions of the glucose unit (for example, This means the average degree of substitution (substitution ratio) of acyl groups and graft chains (or the average number of moles of derivatized hydroxyl groups at the 2, 3 and 6 positions of the glucose unit). "I agree."

In the present specification, the term “hydroxy acid component” is used to mean not only a hydroxy acid but also a lower alkyl ester of a hydroxy acid (eg, C _1-2 alkyl ester) and a cyclic ester of a hydroxy acid.

  In the modified glucan derivative of the present invention, since the ratio of the hydroxy acid component substituted for the glucan derivative is adjusted, the original characteristics of the glucan derivative (such as cellulose acylate) can be modified even with an α-hydroxy acid component such as lactide. Without impairing the optical properties, optical properties can be imparted and practicality is high. Moreover, the modified glucan derivative of the present invention can impart excellent heat resistance and can be suitably used for optical applications such as an optical film. Furthermore, it is excellent in optical characteristics (optical isotropy, optical anisotropy, etc.), can be suitably used even for applications requiring heat resistance, and has high practicality.

[Modified glucan derivative]
The hydroxy acid-modified glucan derivative of the present invention is composed of a glucan derivative and a graft chain formed by graft polymerization of a hydroxy acid component on the hydroxyl group of the glucan derivative.

(Glucan derivative)
The glucan derivative is not particularly limited as long as the hydroxy acid component has a hydroxyl group for graft polymerization. Usually, a part of the hydroxyl group of the glucose unit of glucan is derivatized (etherified, esterified, etc.). It may be a glucan derivative. That is, the glucan derivative is a derivative in which an acyl group or the like is substituted (bonded) to a hydroxyl group (hydroxyl groups located at positions 2, 3 and 6 of the glucose unit) contained in the glucose unit (or glucose skeleton) of the glucan. In many cases, the glucan derivative is a converted glucan derivative in which a part of the hydroxyl group remains. The glucan derivatives having a hydroxyl group may be used alone or in combination of two or more.

  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, lennatine, and dextran. Among these glucans, cellulose and starch (or amylose) are preferable from an industrial viewpoint, and cellulose is particularly preferable. Glucans may be used alone or in combination of two or more.

  Specific examples of the glucan derivative include etherified glucan and esterified glucan. Below, a cellulose derivative is explained in full detail as a typical glucan derivative.

Cellulose derivatives include cellulose ethers [eg, alkyl cellulose (eg, C _1-4 alkyl cellulose), hydroxyl alkyl cellulose (eg, hydroxy C _2-4 alkyl cellulose, etc.), hydroxyalkyl alkyl cellulose (hydroxy C _2-4 alkyl, etc.). C _1-4 alkyl cellulose, etc.), cyanoalkyl cellulose, carboxyalkyl cellulose (carboxymethyl cellulose, etc.)], cellulose esters (cellulose acylate; inorganic acid esters such as cellulose nitrate and cellulose phosphate; inorganic acids such as cellulose nitrate acetate) And mixed acid cellulose esters of organic acids).

Preferred cellulose derivatives include acylcellulose (or cellulose acylate) from the viewpoint of excellent optical properties. In the cellulose acylate, the acyl group can be appropriately selected depending on the application. For example, an alkylcarbonyl group [for example, a C _2-10 alkylcarbonyl group such as an acetyl group, a propionyl group, a butyryl group (for example, a C _2-8). Alkylcarbonyl group, preferably C _2-6 alkylcarbonyl group, more preferably C _2-4 alkylcarbonyl group)], etc.], cycloalkylcarbonyl group (for example, C _5-10 cycloalkylcarbonyl group such as cyclohexylcarbonyl group, etc.) And arylcarbonyl groups (for example, C _7-12 arylcarbonyl groups such as benzoyl group and carboxybenzoyl group). The acyl group may be bonded to the glucose unit of cellulose alone or in combination of two or more. Of these acyl groups, an alkylcarbonyl group is preferred. In particular, among these acyl groups, at least an acetyl group is preferably bonded to a glucose unit. For example, only an acetyl group may be bonded, and an acetyl group and another acyl group (C _3-4 acyl group). Group, etc.) may be bonded.

Typical cellulose acylates include cellulose C _2-6 acylates such as cellulose acetate (cellulose acetate), cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, preferably cellulose C _{2− 4-} Acylate etc. are mentioned, and especially cellulose acetate (especially cellulose diacetate or cellulose triacetate) is preferable.

  In glucan derivatives (especially cellulose derivatives such as cellulose acylates such as cellulose acetate), the average degree of substitution (average degree of substitution such as acyl groups, glucose of derivatized hydroxyl groups at the 2, 3 and 6 positions of glucose units) The average number of moles per mole of unit can be selected from the range of 0.5 to 2.999 (for example, 0.7 to 2.99), for example, 0.9 to 2.98 (for example, 1.2). To 2.97), preferably 1.5 to 2.96 (for example, 1.5 to 2.95), more preferably 1.7 or more (for example, 1.8 to 2.95, preferably 1.9). To 2.93)], especially 2.25 or more [eg 2.3 or more (eg 2.3 to 2.95), preferably 2.35 to 2.93 (eg 2.38 to 2.88). ), More preferably 2. Or more (e.g., 2.5 to 2.85) may be, usually from 2 to 2.95 (e.g., 2.05 to 2.92) may be used. Use of a glucan derivative having a relatively high degree of substitution [for example, an average degree of substitution of 2.25 or more (for example, 2.3 or more, preferably 2.4 or more)] is advantageous in terms of moisture resistance and optical properties. is there. In addition, the average substitution degree of an acyl group or the like is particularly 2.6 or less [eg, 1.5 to 2.55, preferably less than 2.5 (eg, 1.7 to 2.49), more preferably 1 0.8-2.48, ordinarily 1.9-2.46 (for example, about 2.2.45)]. When a glucan derivative having such an average degree of substitution is used, even if the hydroxy acid component is composed of an α-hydroxy acid component such as lactide, the glucan derivative is easily plasticized by grafting, which is advantageous from the viewpoint of thermoplasticization.

  Moreover, as a glucan derivative, a relatively high average substitution degree, for example, an average substitution degree of 2.7 or more (for example, 2.72 to 2.999), preferably 2.75 or more (for example, 2.78 to 2.995). ), More preferably 2.8 or more (eg 2.83 to 2.99), especially 2.85 or more (eg 2.87 to 2.97), usually 2.88 to 2.95 (eg 2 .89-2.93) glucan derivatives (especially cellulose acylates such as cellulose acetate) may be used. Glucan derivatives having such a high average substitution degree (especially cellulose acetate, ie, cellulose triacetate) As will be described later, it is useful for obtaining a film (a film having optical isotropy) having a remarkably small retardation value.

  The degree of polymerization of the glucan derivative (or glucan) is not particularly limited as long as the modified glucan derivative can be used for a desired purpose, and can be suitably used as long as it is about the same as a commercially available product currently industrially available. For example, the average polymerization degree (viscosity average polymerization degree) 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 glucan derivative (cellulose acylate etc.) may use a commercially available compound (for example, cellulose acetate etc.), and may synthesize | combine by a conventional method. For example, cellulose acylate is usually obtained by activating cellulose with an organic carboxylic acid corresponding to an acyl group (such as acetic acid) and then using an acylating agent (for example, an acid anhydride such as acetic anhydride) using a sulfuric acid catalyst. Prepare triacyl ester (especially cellulose triacetate), inactivate excess acylating agent (especially acid anhydride such as acetic anhydride) and acylate by deacylation or saponification (hydrolysis or aging) It can be manufactured by adjusting the degree. 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. Further, other glucans (for example, starch and the like) can be acylated (and deacylated) in the same manner as in the case of cellulose acylate.

  The graft chain is formed by graft polymerization (or reaction) of a hydroxy acid component to the hydroxyl group of this glucan derivative. That is, in the modified glucan derivative, the derivatized group (such as an acyl group) and the graft chain of the hydroxy acid component are bonded via the hydroxyl group of the glucose unit of the glucan derivative. As will be described later, the modified glucan derivative may have a hydroxyl group (unsubstituted hydroxyl group) remaining without being derivatized (acylation, grafting, etc.).

(Hydroxy acid component)
The hydroxy acid component is composed of an α-hydroxy acid component. As the α-hydroxy acid component, α-hydroxy acid [for example, α-hydroxy C _2-10 alkanecarboxylic acid such as glycolic acid, lactic acid (L-lactic acid, D-lactic acid), α-oxybutyric acid, preferably α -Hydroxy C _2-6 alkanecarboxylic acid, more preferably α- _{hydroxyC 2-4} alkanecarboxylic acid)], cyclic diesters [eg glycolide, lactide (L-lactide, D-lactide or mixtures thereof), etc. C _4-15 cyclic diester, preferably C _4-10 cyclic diester etc.] and the like. The hydroxy acid may be converted to a lower alkyl ester (for example, C _1-2 alkyl ester). Among these α-hydroxy acid components, lactic acid (L-lactic acid, D-lactic acid, or a mixture thereof) or lactide (L-lactide, D-lactide, or a mixture thereof) is preferable. The α-hydroxy acid component may be used alone or in combination of two or more.

  The hydroxy acid component may be composed of at least an α-hydroxy acid component, and may be composed of an α-hydroxy acid component and a lactone component.

Examples of the lactone component (or other hydroxy acid component) include lactones (or cyclic monoesters), hydroxy acids other than α-hydroxy acids, and the like. Examples of the lactone include β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, laurolactone, enanthlactone, dodecanolactone, stearolactone, α-methyl-ε-caprolactone. , Β-methyl-ε-caprolactone, γ-methyl-ε-caprolactone, β, δ-dimethyl-ε-caprolactone, 3,3,5-trimethyl-ε-caprolactone, C _3-20 lactone (preferably C _{4 -15} lactone, more preferably C _4-10 lactone). In addition, as the hydroxy acid component, a hydroxy acid excluding α-hydroxy acid (glycolic acid, lactic acid, etc.), for example, an aliphatic oxycarboxylic acid (eg, hydroxy C _2-10 alkane carboxylic acid such as 6-hydroxyhexanoic acid) Etc.). The hydroxy acid may be converted to a lower alkyl ester (for example, C _1-2 alkyl ester).

The lactone component is preferably composed of at least a lactone, and particularly preferred lactones include C _4-10 lactones (eg, C _5-8 lactones such as β-butyrolactone, δ-valerolactone, ε-caprolactone), particularly ε -Caprolactone is included. These lactone components may be used alone or in combination of two or more.

(Graft chain)
The average degree of polymerization of the graft chain (or the average number of moles added in terms of hydroxy acid of the hydroxy acid component constituting the graft chain) is 1 to 50 (for example, 1 in terms of lactic acid in terms of lactide). About 5 to 20), for example, 1 to 15 (for example, 1 to 13), preferably 1.5 to 12 (for example, 2 to 12), and more preferably 2.5 to 11 (for example, 3 to 10), usually about 2.5 to 10.5, and particularly about 1.8 to 9 (for example, about 2 to 7). 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.

  The average molecular weight (for example, number average molecular weight) of the graft chain can be selected from the range of 5000 or less (for example, 2000 or less), for example, less than 1000 (for example, about 80 to 950), preferably 900 or less (for example, 150 to about 870), more preferably 850 or less (for example, about 200 to 830), particularly 800 or less (for example, about 250 to 780), and usually 750 or less (for example, about 300 to 700).

  In addition, when the polymerization degree and molecular weight of the graft chain increase, the graft chain part has crystallinity, and when a thermal history higher than the glass transition temperature acts on the modified glucan derivative, whitening or haze deterioration is likely to occur due to crystallization. Become. For this reason, as described above, in the modified glucan derivative, it is preferable to adjust the polymerization degree and molecular weight of the graft chain to be relatively small.

  In the modified glucan derivative, the ratio of the graft-polymerized hydroxy acid component is an average of 0.1 to 5 mol (for example, 0.15 to 4.5) in terms of hydroxy acid with respect to 1 mol of glucose unit constituting the glucan derivative. Mol), for example, 0.2-4 mol (for example, 0.25-3.5 mol), preferably 0.3-3 mol (for example, 0.35-2.5), more preferably May be 0.4 to 3.2 mol (for example, 0.5 to 3 mol), usually about 0.6 to 3.5 mol, particularly 3 mol or less (for example, 0.1 to 2.5 mol). Mol, preferably 0.15 to 2 mol, more preferably 0.2 to 1.8 mol), usually 1.2 or less [e.g. 0.02 to 1.1, preferably 0.05 to 1 (e.g. 0.1 to 0.9), more preferably less than 0.5 (for example, 0. It may be 0.45) about]. It may be. The ratio (mole) of the hydroxy acid component refers to the hydroxy acid component added (or grafted) to the entire glucose unit of cellulose acylate regardless of whether the degree of polymerization of the graft chain is 1 or greater. The average number of moles added is shown. In the present invention, by grafting the hydroxy acid component at such a relatively small ratio, even if it is modified with an α-hydroxy acid component such as lactide, the characteristics of the glucan derivative (cellulose acylate, etc.) are lowered. And the glucan derivative can be modified. Further, by grafting at such a ratio, the heat resistance of the modified glucan derivative can be efficiently improved.

  When the hydroxy acid component is composed of an α-hydroxy acid component (for example, lactic acid and / or lactide) and a lactone component (for example, lactone), graft polymerization of the α-hydroxy acid component and the graft polymerization is performed in the modified glucan derivative. The ratio with respect to the lactone component is, in terms of hydroxy acid, the former / the latter (molar ratio) = 99/1 to 1/99, preferably 95/5 to 5/95 (for example, 90/10 to 10/90), More preferably, it may be about 80/20 to 20/80 (for example, 75/25 to 25/75).

  In the modified glucan derivative, the average degree of substitution of the graft chain (that is, the average degree of substitution of the graft chain with the hydroxy acid component grafted to the hydroxyl group of the glucan derivative, the average degree of substitution of the hydroxyl group grafted with the hydroxy acid component, glucose units The average number of moles of hydroxyl group derivatized by graft polymerization at the 2, 3 and 6 positions of the glucose unit per mole of glucose is, for example, 0.01 to 2 (for example, 0.015 to 1.5), preferably Is 0.02-1 (e.g. 0.025-0.8), more preferably 0.03-0.7 (e.g. 0.035-0.6), especially 0.04-0.5 (e.g. 0.045 to 0.4).

  In the modified glucan derivative, the ratio of the average substitution degree (number of moles) of the derivatized hydroxyl group other than the graft chain (for example, acyl group) and the average substitution degree (number of moles) of the graft chain is the former / the latter = 40/60 to 99.9 / 0.01 (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, it may be about 80/20 to 98/2 (for example, 85/15 to 97.5 / 2.5). In particular, when the average degree of substitution of a derivatized hydroxyl group such as an acyl group is relatively large, the ratio between the average degree of substitution of the derivatized hydroxyl group and the average degree of substitution of the graft chain is the former / the latter = 88 / 12 to 99.9 / 0.01 (for example, 90/10 to 99.7 / 0.3), preferably 93/7 to 99.5 / 0.5 (for example, 95/5 to 99.2 / 0) .8), more preferably about 96/4 to 99/1 (for example, 97/3 to 98.8).

  In the modified glucan derivative, the ratio of hydroxyl group (residual hydroxyl group) (or the ratio of hydroxyl group remaining without being derivatized or grafted to 1 mol of glucose unit) is 1 mol of glucose unit. For example, it can be selected from an average range of 0 to 1.2 mol, for example, 0.01 to 1 mol, preferably 0.02 to 0.8 mol, preferably 0.03 to 0.7 mol, and more preferably May be about 0.04 to 0.6 mol, usually about 0.05 to 0.55 mol. In particular, when the average degree of substitution of a derivatized hydroxyl group such as an acyl group is relatively large, the ratio of the hydroxyl group is, for example, an average of 0 to 0.3 mol, preferably 0.00. It may be about 01 to 0.2 mol, preferably 0.02 to 0.1 mol, more preferably about 0.03 to 0.08 mol.

In the modified glucan derivative, the 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 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., 5-8 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 two or more.

  In the modified glucan derivative in which the hydroxyl group is protected by the protecting group, the ratio of the protecting group (or the protecting ratio of the hydroxy group of the graft chain) can be selected from the range of 0.7 to 1 mol with respect to 1 mol of the graft chain. For example, it may be about 0.9 to 1 mol, preferably about 0.95 to 0.999 mol.

  In addition, the modified graft 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.

  The modified glucan derivative of the present invention has a relatively high glass transition temperature and high heat resistance despite having a graft chain grafted with a hydroxy acid component. The glass transition temperature of the glucan derivative of the present invention can be selected from the range of 70 ° C. or higher (for example, about 73 to 220 ° C.), for example, 75 to 200 ° C. (for example, 78 to 190 ° C.), preferably 80 ° C. or higher [ For example, 80 to 180 ° C. (for example, 82 to 170 ° C.)], more preferably about 85 to 160 ° C., and usually about 90 to 155 ° C. (for example, 95 to 150 ° C.). The glass transition temperature of the modified glucan derivative can be adjusted, for example, by adjusting the graft ratio of the hydroxy acid component, the degree of polymerization of the graft chain, the type of glucan derivative (substitution degree, type of substituent such as acyl group, etc.), etc. Can be adjusted. Usually, when the glucan derivative is the same, the glass transition temperature seems to decrease as the amount of hydroxy acid added to the glucan derivative or the degree of polymerization of the graft chain increases.

  In addition, the modified glucan derivative of the present invention is excellent in moisture resistance. For example, the water absorption of the modified glucan derivative is 8% or less (for example, about 0 to 7.5%) and 5% or less (for example, 0. 1 to 4%), preferably 3% or less (for example, about 0.2 to 2.7%), more preferably 2.5% or less (for example, about 0.3 to 2.2%), especially 2 % Or less (for example, about 0.5 to 1.8%).

(Method for producing modified glucan derivative)
The modified glucan derivative of the present invention can be obtained by reacting a glucan derivative and a hydroxy acid component (ring-opening polymerization reaction or condensation reaction). That is, a modified glucan derivative can be prepared by graft polymerization of a hydroxy acid component to a glucan derivative. The graft reaction (graft polymerization reaction) is a ring-opening reaction (ring-opening polymerization reaction, ring-opening grafting reaction) involving ring opening of the cyclic ester when a cyclic ester (eg, lactide) is used as the hydroxy acid component. Yes, it is a condensation reaction (condensation grafting reaction) when a hydroxy acid (such as lactic acid) is used. In the present invention, usually, a ring-opening grafting reaction using a cyclic ester can be suitably used.

  The water content of the glucan derivative and the hydroxy acid component used for graft polymerization (particularly, ring-opening polymerization reaction using a cyclic ester) is preferably as small as possible, and each is 0.5% by weight or less based on the whole. [0 (or detection limit) to about 0.3% by weight], preferably 0.1% by weight or less (for example, about 0.0001 to 0.05% by weight), more preferably 0.01% by weight or less (for example, , About 0.0003 to 0.005% by weight). The water content can be reduced by a conventional method, for example, distillation, contact with a desiccant (such as magnesium sulfate), or the like.

  In the reaction (graft polymerization), the ratio (use ratio) of the hydroxy acid component is not particularly limited and is, for example, 1 to 300 parts by weight (for example, 5 to 250 parts by weight), preferably 100 parts by weight of the glucan derivative. May be 10 to 200 parts by weight, more preferably 15 to 150 parts by weight (for example, 20 to 130 parts by weight), and usually 120 parts by weight or less (for example, 20 to 110 parts by weight).

  In the reaction (graft polymerization), the ratio (use ratio) of the hydroxy acid component is not particularly limited and is, for example, 1 to 300 parts by weight (for example, 5 to 250 parts by weight), preferably 100 parts by weight of the glucan derivative. May be 10 to 200 parts by weight, more preferably 15 to 150 parts by weight (for example, 20 to 130 parts by weight), and usually 120 parts by weight or less (for example, 20 to 110 parts by weight).

  The reaction (or graft polymerization) 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 acts as a catalyst for graft polymerization (particularly, ring-opening polymerization reaction using a cyclic ester) of a hydroxy acid component (such as lactide), and a metal that does not initiate polymerization alone Complexes (or metal compounds) may be used. By using such a catalyst (and a specific solvent described later), the formation of a homopolymer of a hydroxy acid component can be remarkably suppressed, and a graft polymer (modified glucan derivative) can be obtained with high efficiency. Further, when such a catalyst (and a specific solvent described later) is used, the degree of substitution of the acyl group as seen in the method of Patent Document 1 does not decrease, and the product after graft polymerization (that is, In the modified glucan derivative), the acyl substitution degree of the glucan derivative as a raw material can be reflected, and 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 start the polymerization is composed of a central metal and a ligand that coordinates to the central metal, and a specific ligand (or hydroxy acid component) that constitutes the metal complex. Examples of ligands that do not exhibit polymerization activity with respect to or a ligand that is inactive with respect to a hydroxy acid component include, for example, 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, etc.) Aliphatic carboxylic acids such as C _1-20 alkanoic acids such as hexanoic acid and 2-ethylhexanoic acid; aromatic carboxylic acids such as benzoic acid], carbonic acid, Examples thereof include ligands corresponding to oxalic acid (for example, halo, alkyl, acylacetonato, acyl) and the like. 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 carbonates, carboxylic acid alkaline earth metal salts such as calcium acetate), zinc compounds (zinc acetate, acetyl) Acetonate zinc, 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 alkanecarboxylate, preferably Tin C _4-14 alkanecarboxylates), alkyltin carboxylates (eg mono- or di-C _1-12 alkyl tin C _2-18 alkane carboxylates such as dibutyltin diacetate, dibutyltin dilaurate, monobutyltin trioctylate, etc.) Tin (or tin) carboxylates; alkyl tin oxides (for example, mono- or dialkyl tin oxides such as monobutyltin oxide and dibutyltin oxide); tin halides; tin halide acetylacetonate; inorganic acid tin (tin nitrate, sulfuric acid) Tin, etc.), lead compounds (eg, lead acetate), antimony compounds (eg, antimony trioxide), bismuth compounds (eg, bismuth acetate), typical metal compounds or typical metal complexes; rare earth metal compounds (eg, vinegar) Carboxylic acid rare earth metal salts such as lanthanum and samarium acetate), titanium compounds (such as titanium acetate), zirconium compounds (such as zirconium acetate and zirconium acetylacetonate), niobium compounds (such as niobium acetate), iron compounds (iron acetate, iron acetyl) Transition metal compounds such as acetonato).

  Of these catalysts, tin complexes (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.

  In addition, the reaction (graft polymerization reaction) may be performed without a solvent or in a solvent, and may usually be performed in a solvent. Examples of the solvent include hydrocarbons, ethers (tetrahydrofuran, dioxane, dioxolane, etc.), esters (methyl acetate, ethyl acetate, etc.), nitrogen-containing solvents (nitromethane, acetonitrile, N-methylpyrrolidone, dimethylformamide, etc.), Ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, etc.), sulfoxides (dimethyl sulfoxide, etc.) may be used, and excess hydroxy acid components (eg lactone, lactide, etc.) It may be used. The solvents may be used alone or in combination of two or more.

  In addition, in the ring-opening polymerization reaction system using a cyclic ester, the influence of water in the polymerization system or the reaction can be suppressed as much as possible by using a specific solvent having low solubility in water in addition to the specific catalyst. Because of this, a modified glucan derivative can be obtained while suppressing the formation of a homopolymer of a hydroxy acid component at a high level. Specifically, the solubility in water at 20 ° C. of the solvent used for the graft polymerization reaction can be selected from the range of 10% by weight or less [for example, 0 (or detection limit) to 8% by weight], for example, 7% by weight or less. (For example, about 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) 1) or less (for example, 0.001 to 0.8 wt., Preferably 0.002 to 0.5 wt.%, More preferably about 0.003 to 0.3 wt.%).

Specific examples of the solvent having low solubility in water include aliphatic hydrocarbons [eg, alkanes (eg, C _7-20 alkanes such as heptane, octane, nonane, decane, etc.), cycloalkanes (eg, C _4-10 cycloalkane such as cyclohexane) and the like], aromatic hydrocarbons (eg, benzene, toluene, xylene (o, m or p-xylene), C _6-12 arenes such as ethylbenzene, preferably C _{6-6 10} arene), aliphatic ketones [e.g., dialkyl ketones (e.g., diethyl ketone, methyl n- propyl ketone, methyl isopropyl ketone, methyl n- butyl ketone, di-n- propyl ketone, diisopropyl ketone, such as diisobutyl ketone _{C 5- 15} dialkyl ketones, preferably _{C 7-10} Zia Kirketon), etc.], chain ethers [such as dialkyl ethers (C _6-10 dialkyl ether), non-halogenated solvents such as alkyl aryl ethers (such as anisole), etc.], a halogen-based solvent. 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.) .

  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 (grafting reaction) may be performed at room temperature, and may be performed under heating in order to perform the reaction efficiently. In the ring-opening polymerization reaction, when the boiling point of the solvent is A (° C.), the reaction temperature is usually a temperature equal to or higher than the boiling point of the solvent, for example, A to (A + 30) (° C.) [for example, A to (A + 25). ) (° C.)], preferably A to (A + 22) (° C.), more preferably about (A + 3) to (A + 20) (° C.). In addition, when a solvent is a mixed solvent, it is good also considering the boiling point of the solvent with the lowest boiling point in a pure substance as the said boiling point. When the reaction is carried out at a low temperature, the effect of suppressing the influence of water in the polymerization system (particularly the ring-opening polymerization system) is small, the formation of homopolymer cannot be suppressed, and the polymerization is carried out at a temperature that is too higher than the boiling point of the solvent used. In some cases, the reflux of the solvent becomes violent and control becomes difficult. Although specific reaction temperature is based also on the kind of solvent, it is 60-250 degreeC, for example, Preferably it is 80-220 degreeC, More preferably, it is 100-180 degreeC (for example, 105-170 degreeC), Usually 110-160 degreeC. It may be a degree.

  The reaction may be performed in air or in an inert atmosphere (such as a rare gas such as nitrogen or helium), and can usually be performed in an inert atmosphere. Moreover, you may perform reaction under a normal pressure or pressurization. Furthermore, the grafting may be performed with stirring.

  In addition, in order to suppress the production | generation of a homopolymer of a hydroxy acid component, or a side reaction efficiently, you may perform reaction in a state with as little water as possible. For example, in the reaction (particularly, ring-opening polymerization reaction), the water content with respect to the total amount of the glucan derivative, the hydroxy acid component, and the solvent is, for example, 0.3 wt% or less [0 (or detection limit) to 0.25 wt. %], 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, about 0.0005 to 0.12% by weight). In particular, it may be 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.

  In the graft polymerization reaction, the reaction time is not particularly limited, but may be, for example, 10 minutes to 24 hours, preferably 30 minutes to 10 hours, and more preferably about 1 to 6 hours.

  In the case of protecting the hydroxyl group and / or the carboxyl group, the protection is performed by separating (and purifying) the product obtained by the reaction (grafting), and by separating (and purifying) the graft product obtained by Protecting agent corresponding to the protecting group [for example, acylating agent such as acid halide and acid anhydride, protecting agent for hydroxyl group such as alkenyl acylate (for example, isopropenyl acetate, etc.); protecting agent for carboxyl group such as carbodiimide compound Etc.] may be allowed to react with each other, or may be carried out continuously in the same reaction system as the grafting. When the reaction is carried out in the same reaction system, a solvent may be added as necessary to reduce the viscosity of the reaction system, and a large amount or an excessive amount of a hydroxy acid component is used in advance in the grafting. An acid component may be used as a solvent.

  After completion of the reaction (after graft polymerization, after graft polymerization and protection of hydroxyl group), the reaction mixture is combined with a conventional method, for example, separation means such as filtration, concentration, distillation, extraction, neutralization and precipitation, or a combination thereof. Separation and purification can be performed by separation means.

  In the above method, A1 (mol) is the grafted hydroxy acid component, and A2 (mol) is the hydroxy acid component that forms the homopolymer of the hydroxy acid component that is produced (specifically, produced as a by-product). When [A1 / (A1 + A2)] × 100 (%), the graft efficiency is about 20% or more (for example, about 40 to 100%), 70% or more (for example, 80 to 100%), Preferably it is 85% or more (for example, about 88 to 99.9%), more preferably 90% or more (for example, about 93 to 99.8%), more preferably 95% or more (for example, 96 to 99.7%). Degree). In addition, it means that the production | generation of the homopolymer of a hydroxy acid component is suppressed, so that grafting efficiency is high.

[Optical molded product]
The modified glucan derivative of the present invention is useful for forming an optical molded article. The form of the optical molded body is not particularly limited, and may be any of a two-dimensional molded body (film, sheet, coating film (or thin film), etc.), a three-dimensional molded body such as a curved shape or a three-dimensional shape. Good.

  In particular, since the modified glucan derivative of the present invention has high heat resistance and optical properties (orientation birefringence), an optical film can be suitably formed. That is, the optical film of the present invention is formed (or configured) with the modified glucan derivative (for example, modified cellulose acylate).

  Below, an optical film and its manufacturing method are explained in full detail.

  The optical film (modified glucan derivative film, sometimes simply referred to as film) of the present invention is prepared by a melt film forming method (extrusion molding method, etc.), a solution film forming method (casting), depending on the degree of substitution and the type of acyl group. Method). Usually, a film having excellent flatness may be produced by a solution casting method.

  In the solution casting method, the optical film is cast by casting a dope (or an organic solvent solution) containing a modified glucan derivative and an organic solvent onto a peelable support, and peeling off the formed film from the peelable support. Can be manufactured. The peelable support may usually be a metal support (such as stainless steel), or may be in the form of a drum or endless belt. The surface of the support is usually mirror-finished and often smooth.

The organic solvent for preparing the dope may be a halogen-based organic solvent (particularly a chlorine-based organic solvent) or a non-halogen-based organic solvent (particularly a non-chlorine-based organic solvent). The organic solvents may be used alone or in combination of two or more. For example, a chlorinated organic solvent and a non-chlorinated organic solvent may be combined. Examples of the halogen organic solvent (particularly chlorine organic solvent) include halogenated hydrocarbons (particularly chlorinated hydrocarbons) such as dichloromethane and chloroform. Examples of non-halogen organic solvents (particularly non-chlorine organic solvents) include esters (acetates such as methyl acetate, ethyl acetate, amyl acetate, and butyl acetate) and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone). Dialkyl ketones such as cyclohexanone), ethers (chain ethers such as diethyl ether, cyclic ethers such as dioxane and tetrahydrofuran), alcohols (for example, C such as methanol, ethanol, isopropanol, and n-butanol). _1-4 alkanols).

  For the dope, various additives such as plasticizer [phosphate ester plasticizer, carboxylic ester plasticizer (phthalate ester, adipic acid ester, sebacic acid ester, citrate ester, etc.), triacetin etc.], Stabilizers (antioxidants, ultraviolet absorbers, deterioration inhibitors, etc.), lubricants (particulate lubricants), flame retardants, mold release agents and the like may be added. Further, a retardation increasing agent (such as a retardation increasing agent described in JP-A-2001-139621), a release agent (such as a releasing agent described in JP-A-2002-30909), or the like may be added to the dope. .

  The dope can be prepared by using a conventional method such as a high temperature dissolution method or a cooling dissolution method. The cellulose ester concentration in the dope may be about 10 to 35% by weight, preferably about 20 to 30% by weight (for example, 15 to 25% by weight). Moreover, in order to obtain a high quality film (such as a film for a liquid crystal display device), the dope may be further filtered.

  A film can be produced by casting a dope on a support using a casting die or the like and drying. Usually, a dope is cast on a support, preliminarily dried, and then a predried film containing an organic solvent is dried to produce a film.

  In the melt film forming method, for example, the modified glucan derivative (and other components such as a plasticizer, if necessary) is melt-mixed with an extruder, extruded from a die (T-die, ring die, etc.), and cooled. You may manufacture a film by doing. The melt mixing temperature can be selected from a range of, for example, about 120 to 250 ° C.

  The thickness of the film can be selected according to the application, and may be, for example, about 5 to 200 μm, preferably about 10 to 150 μm, and more preferably about 20 to 120 μm.

  The film may be stretched. The film of the present invention is excellent in stretchability because the glucan derivative is modified with a hydroxy acid component. And by an extending | stretching process, an film can be efficiently orientated and an optically anisotropic film can be obtained simply. The film can be oriented by conventional methods (drawing, stretching, etc.), for example, uniaxial or biaxial, and may be oriented using the draw ratio of the take-up roll, gripping the end of the film with a chuck You may extend and orient. As the stretching method, heat stretching can be preferably used. For example, in the solution casting method, the film after drying or a pre-dried film containing a solvent may be oriented by stretching. In the melt film-forming method, the film-like melt extruded from the die of the extruder may be taken and cooled by a cooling means such as a cooling roll while being stretched in the uniaxial direction, and the film-like melt extruded from the die may be removed. It may be cooled and stretched at a predetermined temperature. Further, the film only needs to be oriented in at least one direction (vertical or take-up direction MD or width direction TD), and may be oriented in a tolerance or orthogonal direction. Further, the stretching treatment may be either uniaxial stretching or biaxial stretching.

  The degree of orientation (stretch ratio) of the film is about 1.05 to 8 times, preferably 1.1 to 4 times, more preferably 1.2 to 3 times, particularly about 1.4 to 2 times in at least one direction. There may be. In the biaxially stretched film, the MD direction is about 1.1 to 8 times (for example, 1.1 to 5 times, preferably 1.1 to 2 times, more preferably 1.2 to 1.5 times), It may be about 1.0 to 4 times (for example, 1.0 to 3 times, preferably 1.0 to 2 times, more preferably 1.1 to 1.5 times) in the TD direction.

  The stretching temperature of the film (unstretched film) is usually a temperature not lower than the glass transition temperature of the modified glucan derivative and can be selected at a temperature lower than the melting point. For example, when the glass transition temperature of the modified glucan derivative is A ° C, the stretching temperature may be A to A + 70 (° C), preferably A + 3 to A + 50 (° C), more preferably about A + 5 to A + 30 (° C). .

  In the present invention, an optical film having a desired retardation value in a wide range can be prepared. For example, in the film of the present invention (stretched film or unstretched film), the retardation value Re in the film plane and the retardation value Rth in the thickness direction of the film are each −250 nm to +500 nm (for example, −200 nm to +400 nm), preferably Is about −100 nm to +350 nm, more preferably about −50 nm to +300 nm. The in-plane retardation value Re may usually be a value in the vicinity of the center (or the center) of the film.

  In addition, the film of the present invention can easily impart excellent optical properties by a stretching process. For example, in a film subjected to a stretching process (such as a uniaxial or biaxial stretching process, such as a uniaxial stretching process in the width direction), the film The in-plane retardation value Re is 0 to 400 nm (for example, 5 to 350 nm), preferably 10 to 300 nm, more preferably 20 to 300 nm (for example, 25 to 250 nm), particularly 30 to 220 nm (for example, 35 to 200 nm). It may be a degree. In addition, in a film that has been subjected to stretching treatment (uniaxial or biaxial stretching treatment, such as uniaxial stretching treatment in the width direction), the retardation value Rth in the thickness direction of the film is −150 nm to +500 nm (for example, −100 nm to +450 nm), Preferably, it may be about −80 nm to +400 nm, more preferably about −60 nm to +350 nm. In particular, in a film subjected to stretching treatment (uniaxial or biaxial stretching treatment, such as uniaxial stretching treatment in the width direction), the retardation value Rth in the thickness direction of the film is −80 nm to +500 nm (for example, −60 nm to +450 nm), Preferably, it may be about −50 nm to +400 nm, more preferably about −45 nm to +350 nm (for example, −40 nm to +320 nm).

  In the present invention, a film is formed with a specific modified glucan derivative [for example, a modified glucan derivative having a cellulose acetate having an average substitution degree of 2.75 or more (for example, about 2.85 to 2.95) as a glucan derivative]. Optically isotropic film [for example, the in-plane retardation value Re is about 0 to 10 nm (for example, about 0 to 3 nm) and the thickness direction retardation value Rth is −10 nm to +10 nm (for example, An optical film of about −5 nm to +5 nm) can also be prepared. Such a film having optical isotropy is usually a film that has not been stretched (unstretched film) in many cases.

  The retardation value of the film (in-plane retardation value Re, thickness direction retardation value Rth) 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. Can be calculated based on the formula defined by the following formula.

Re = (nx−ny) × d
Rth = {(nx + ny) / 2−nz} × 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, nz represents the refractive index in the film thickness direction, and d represents the film thickness). )
In addition, the retardation value of the film which does not contain a plasticizer may be sufficient as the said retardation value normally.

  The modified glucan derivative of the present invention retains the characteristics of the glucan derivative sufficiently despite the α-hydroxy acid component being graft-polymerized, and also has optical characteristics (optical isotropic, optical Excellent anisotropy) and high practicality. Further, the optical characteristics can be easily controlled by adjusting the kind of glucan derivative, the graft ratio, the draw ratio, etc., and a wide range of optical characteristics can be imparted depending on the application. In addition, excellent optical characteristics can be easily imparted without causing whitening or a decrease in transparency associated with crystallization of the graft chain. Furthermore, the modified glucan derivative of the present invention is excellent in transparency and moisture resistance, and is a molded article for optical use [for example, display materials or display elements such as liquid crystal panels, lenses (glass lenses, contact lenses, etc.), etc.] It is useful to form. The molded article for optical use may be a molded article having a three-dimensional form as described above, and is particularly suitable for a film-like molded article. As a film (optical film), for example, a color filter, a base film for a photographic material, a film for a display device (for example, an optical compensation film such as an optical compensation film for a liquid crystal display device) depending on the optical properties to be imparted , Retardation films, protective films (protective films for polarizing plates, etc.), base films for antireflection films, and the like.

  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, “parts” means “parts by weight” unless otherwise specified.

  In the examples, various characteristics were measured as follows.

(Glass-transition temperature)
The glass transition temperature (Tg) was measured using a high-sensitivity differential scanning calorimeter (“DSC6200”, manufactured by Seiko Instruments Inc.) according to the method of JIS K7121 under the following conditions.

Sample weight: 8.0mg
Nitrogen gas inflow rate: 40 ml / min.
Heating rate: 20 ° C./min.
Cooling rate: 20 ° C./min.
Measurement start temperature: 20 ° C
Measurement end temperature: 210 ° C
The glass transition temperature was measured under the same environment by leaving the sample in a constant temperature and humidity room at 23 ° C. and a relative humidity of 50% for 48 hours.

(Retardation value)
Using an automatic birefringence meter (manufactured by Oji Scientific Instruments Co., Ltd., “KOBRA-21ADH”) in an environment of 23 ° C. and 50% RH at a wavelength of 590 nm (film before stretching, after stretching) 3), and the refractive index nx in the slow axis direction, the refractive index ny in the fast axis direction, and the refractive index nz in the thickness direction are obtained. From these values, the in-plane of the film The retardation value Re and the retardation value Rth in the thickness direction of the film were calculated based on the formula defined by the following formula. The in-plane retardation value Re is a value near the center of the film.

Re = (nx−ny) × d
Rth = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness)

(Refractive index)
The films (unstretched films) and press pieces obtained in the examples and comparative examples were left in a constant temperature and humidity room at 23 ° C. and a relative humidity of 50% for 48 hours. The refractive index was measured according to JIS K7142 using “2T” manufactured by Atago.

(Haze)
The films obtained in Examples and Comparative Examples were left in a constant temperature and humidity room at 23 ° C. and a relative humidity of 50% for 48 hours. Under the same environment, the turbidimeter (Nippon Denshoku Industries Co., Ltd., “NDH5000W”) was used. The haze was measured according to JIS K7136.

(Abbe number)
The press pieces obtained in the examples and comparative examples were left in a constant temperature and humidity room at 23 ° C. and a relative humidity of 50% for 48 hours. Under the same environment, Abbe refractometer (manufactured by Atago Co., Ltd., “2T” ) To measure the Abbe number.

(Total light transmittance)
The films (unstretched films) obtained in Examples and Comparative Examples were allowed to stand for 48 hours in a constant temperature and humidity room at 23 ° C. and 50% relative humidity, and a turbidimeter (Nippon Denshoku Industries Co., Ltd., “NDH5000W” The total light transmittance was measured according to JIS K7361-1.

[Example 1]
(Synthesis of graft body)
In a reactor equipped with a stirrer and an irrigation type stirring blade, 70 parts of cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., L-20, substitution degree 2.41), L-lactide (manufactured by Musashino Chemical Laboratory) 30 parts were added and dried under reduced pressure at 65 ° C. for 12 hours at 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 67 parts of cyclohexanone (ANON) that had been dried and distilled in advance was added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Further, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate (graft) was separated by filtration. The coalescence was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-lactide graft copolymer) which L-lactide 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 lactic acid units (lactic acid units) grafted per mole of glucose unit was 0.85, and the average degree of substitution (DS) of graft chains (grafted L-lactide chains) was 0.22. The average degree of polymerization (DPn) of the lactic acid units in the graft chain was 3.9. Moreover, the glass transition temperature of the obtained graft body was 155.9 degreeC.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 7 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 further left for 24 hours to remove bubbles in the dope.

  The dope was cast on a glass plate at a dope temperature of 30 ° 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 leveling, the film was peeled off from the glass plate after drying for 8 minutes with a warm air dryer at 40 ° C. The film was then supported on a stainless steel frame and dried for 20 minutes with a hot air dryer at 100 ° C. to obtain a film with a thickness of 100 μm. Re of the obtained film (film before stretching, unstretched film) was 4 nm, and Rth was 173 nm. The obtained film had a total light transmittance of 93.5%, a refractive index of 1.47, and a haze of 0.5%.

  The obtained film (unstretched film) was 165 using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.3 times in the width direction at ° C. The stretched film had Re of 135 nm and Rth of 287 nm.

  Further, the obtained graft body was supplied to a hot press machine, and the press temperature was 210 ° C., the press pressure was 10 MPa, the cooling temperature was 15 ° C., the press time was 3 minutes, and the width was 5.0 cm. A press piece having a length of 5.0 cm and a thickness of 1.0 mm was molded, and the total light transmittance, refractive index, and Abbe number were measured. The obtained pressed piece had a total light transmittance of 92.6%, a refractive index of 1.47, and an Abbe number of 58.

[Example 2]
(Synthesis of graft body)
In a reactor equipped with a stirrer and an impeller type stirring blade, 50 parts of cellulose acetate (Daicel Chemical Industries, Ltd., L-20, substitution degree 2.41), L-lactide (manufactured by Musashino Chemical Laboratory) 50 parts was added and dried under reduced pressure at 65 ° C. for 12 hours at 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, 67 parts of cyclohexanone (ANON) that had been dried and distilled in advance was added, and the mixture was heated to 160 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 160 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Further, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate (graft) was separated by filtration. The coalescence was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-lactide graft copolymer) which L-lactide 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 lactic acid units (lactic acid units) grafted per mole of glucose units was 1.93, and the average degree of substitution (DS) of graft chains (grafted L-lactide chains) was 0.30. The average degree of polymerization (DPn) of the lactic acid units of the graft chain was 6.4. Moreover, the glass transition temperature of the obtained graft body was 126.7 degreeC.

(Create film)
Using the obtained grafted body, a film having a thickness of 100 μm was obtained in the same manner as in Example 1. Re of the obtained film (film before stretching) was 6 nm, and Rth was 76 nm. Further, the obtained film had a total light transmittance of 93.2%, a refractive index of 1.47 and a haze of 0.7%.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the resulting film (unstretched film) was 135. The film was stretched 1.3 times in the width direction at ° C. The stretched film had Re of 103 nm and Rth of 138 nm.

  Further, the obtained graft body was supplied to a hot press machine, and the press temperature was 210 ° C., the press pressure was 10 MPa, the cooling temperature was 15 ° C., the press time was 3 minutes, and the width was 5.0 cm. A press piece having a length of 5.0 cm and a thickness of 1.0 mm was molded, and the total light transmittance, refractive index, and Abbe number were measured. The obtained press piece had a total light transmittance of 92.5%, a refractive index of 1.47, and an Abbe number of 51.

[Example 3]
(Synthesis of graft body)
In a reactor equipped with a stirrer and an impeller type stirring blade, 50 parts of cellulose acetate (Daicel Chemical Industries, Ltd., L-20, substitution degree 2.41), L-lactide (manufactured by Musashino Chemical Laboratory) 50 parts was added and dried under reduced pressure at 65 ° C. for 12 hours at 4 Torr. After purging with dry nitrogen, a reflux condenser was attached, 67 parts of previously dried and distilled diisopropyl ketone (DIPK) was added, heated to 140 ° C., and stirred to dissolve cellulose acetate uniformly. The water content of the dissolved reaction solution was measured with a Karl Fischer moisture meter and found to be 0.04% by weight. To this reaction solution, 0.25 part of monobutyltin trioctylate was added and heated at 140 ° C. with stirring for 2 hours. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. The L-lactide conversion rate of the obtained reaction product was 84.1% (the average mole number (MS ′) of L-lactide reacted including that homopolymerized with respect to 1 mol of glucose unit from the conversion rate was 3). The acid value of the reaction product after drying under reduced pressure at 60 ° C. and removing the solvent was 5.9 mgKOH / g. Further, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate (graft) was separated by filtration. The coalescence was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-lactide graft copolymer) which L-lactide 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 lactic acid units (lactic acid units) grafted per mole of glucose unit was 2.98 (that is, graft efficiency 96.8%), and the graft chain (grafted L-lactide chain) The average degree of substitution (DS) was 0.32, and the average degree of polymerization (DPn) of lactic acid units in the graft chain was 9.4. Moreover, the glass transition temperature of the obtained graft body was 90.0 degreeC.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 7 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 further left for 24 hours to remove bubbles in the dope.

  The dope was cast on a glass plate at a dope temperature of 30 ° 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 leveling, the film was peeled off from the glass plate after drying for 8 minutes with a warm air dryer at 40 ° C. The film was then supported on a stainless steel frame and dried for 60 minutes with a hot air dryer at 70 ° C. to obtain a film with a thickness of 100 μm. Re of the obtained film (film before stretching) was 1 nm, and Rth was 19 nm. Further, the obtained film had a total light transmittance of 93.4%, a refractive index of 1.47, and a haze of 0.3%.

  The obtained film (unstretched film) was measured using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.3 times in the width direction at ° C. The stretched film had Re of 34 nm and Rth of −43 nm.

  Further, the obtained graft body was supplied to a hot press machine, and the press temperature was 210 ° C., the press pressure was 10 MPa, the cooling temperature was 15 ° C., the press time was 3 minutes, and the width was 5.0 cm. A press piece having a length of 5.0 cm and a thickness of 1.0 mm was molded, and the total light transmittance, refractive index, and Abbe number were measured. The obtained press piece had a total light transmittance of 92.4%, a refractive index of 1.47, and an Abbe number of 50.

[Comparative Example 1]
(Create film)
Instead of the graft body, cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., LT-35, substitution degree 2.90, glass transition temperature 194.1 ° C.) was used in the same manner as in Example 1, A film with a thickness of 100 μm was obtained. Re of the obtained film (film before stretching) was 4 nm, and Rth was 80 nm. Further, the obtained film had a total light transmittance of 93.5%, a refractive index of 1.47 and a haze of 0.6%.

  The obtained film (unstretched film) was 180 using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). When the film was stretched 1.5 times in the width direction at 0 ° C., the film was broken. Therefore, the width of the obtained film was measured at 180 ° C. using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.2 times in the direction. The stretched film had Re of 4 nm, Rth of 70 nm, Re hardly changed, and remained optically uniaxial.

  Further, the obtained graft body was supplied to a hot press machine, and the press temperature was 210 ° C., the press pressure was 10 MPa, the cooling temperature was 15 ° C., the press time was 3 minutes, and the width was 5.0 cm. X An attempt was made to mold a press piece having a length of 5.0 cm and a thickness of 1.0 mm, but could not be molded.

[Comparative Example 2]
(Create film)
In place of the graft, cellulose acetate butyrate (manufactured by Kanto Chemical Co., Ltd., catalog No. 40425-1A, acetyl group substitution degree 1.06, butyryl group substitution degree 1.66, glass transition temperature 139.0 ° C. ) Was used in the same manner as in Example 1 to obtain a film having a thickness of 100 μm. Re of the obtained film (film before stretching) was 8 nm, and Rth was 127 nm. Further, the obtained film had a total light transmittance of 93.4%, a refractive index of 1.47 and a haze of 0.8%.

  The obtained film (unstretched film) was 150 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 in the width direction at ° C. The stretched film had Re of 118 nm and Rth of 89 nm.

  Further, the obtained graft body was supplied to a hot press machine, and the press temperature was 210 ° C., the press pressure was 10 MPa, the cooling temperature was 15 ° C., the press time was 3 minutes, and the width was 5.0 cm. A press piece having a length of 5.0 cm and a thickness of 1.0 mm was molded, and the total light transmittance, refractive index, and Abbe number were measured. The obtained pressed piece had a total light transmittance of 92.3%, a refractive index of 1.47, and an Abbe number of 44.

[Comparative Example 3]
(Synthesis of graft body)
In a reactor equipped with a stirrer and an impeller type stirring blade, 20 parts of cellulose acetate (manufactured by Daicel Chemical Industries, NAC, substitution degree 2.74), 80 parts of L-lactide (manufactured by Musashino Chemical Laboratory) And dried under reduced pressure at 65 ° C. for 24 hours at 4 Torr. Thereafter, purging was performed with dry nitrogen, a reflux condenser was attached, and the mixture was heated to 140 ° C. and stirred to dissolve cellulose acetate uniformly. To this reaction liquid, 0.10 parts of tin octoate was added and heated at 140 ° C. with stirring for 1 hour. Thereafter, the reaction solution was cooled to room temperature to terminate the reaction and obtain a reaction product. Further, 10 parts of the reaction product was dissolved in 90 parts of chloroform, and then slowly dropped into 900 parts of a large excess of methanol, and the precipitated precipitate (graft) was separated by filtration. The coalescence was removed. Furthermore, it heat-dried at 60 degreeC for 5 hours or more, and obtained the graft body (cellulose acetate-lactide graft copolymer) which L-lactide 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 lactic acid units (lactic acid units) grafted per mole of glucose units was 14.1, and the average degree of substitution (DS) of graft chains (grafted L-lactide chains) was 0.23. The average degree of polymerization (DPn) of lactic acid units in the graft chain was 60.5. Moreover, the glass transition temperature of the obtained graft body was 65.0 degreeC.

(Create film)
15 parts by weight of the obtained graft product, 78 parts by weight of methylene chloride, and 7 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 further left for 24 hours to remove bubbles in the dope.

  The dope was cast on a glass plate at a dope temperature of 30 ° 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 leveling, the film was peeled off from the glass plate after drying for 8 minutes with a warm air dryer at 40 ° C. The film was then supported on a stainless steel frame and dried for 120 minutes with a 45 ° C. hot air dryer to obtain a film with a thickness of 100 μm. Re of the obtained film (film before stretching) was 1 nm, and Rth was 4 nm. The obtained film had a total light transmittance of 93.3%, a refractive index of 1.49 and a haze of 1.5%.

  Using the tensile tester (Orientec Co., Ltd., “UCT-5T”) and the environmental unit (Orientec Co., Ltd., “TLF-U3”), the resulting film (unstretched film) was 75. The film was stretched 1.3 times in the width direction at ° C. The stretched film had Re of 34 nm and Rth of −15 nm.

  Further, the obtained graft body was supplied to a hot press machine, and the press temperature was 210 ° C., the press pressure was 10 MPa, the cooling temperature was 15 ° C., the press time was 3 minutes, and the width was 5.0 cm. A press piece having a length of 5.0 cm and a thickness of 1.0 mm was molded, and the total light transmittance, refractive index, and Abbe number were measured. The obtained pressed piece had a total light transmittance of 92.2%, a refractive index of 1.49, and an Abbe number of 41.

  The obtained results are shown in Tables 1 and 2. In Table 1, “CA” represents cellulose acetate, “LA” represents L-lactide, and “Tg” represents glass transition temperature.

Claims (9)

  A hydroxy acid-modified glucan derivative for use in optical applications, comprising a glucan derivative and a graft chain formed by graft polymerization of a hydroxy acid component composed of an α-hydroxy acid component on the hydroxyl group of the glucan derivative An optically modified glucan derivative having an average of 0.1 to 5 mol in terms of hydroxy acid with respect to 1 mol of glucose unit constituting the glucan derivative, in which the proportion of the hydroxy acid component grafted and polymerized is   The modified glucan derivative according to claim 1, wherein the glucan derivative is cellulose acylate having an average acyl group substitution degree of 1.5 to 2.95.   The glucan derivative is cellulose acylate having an average acyl group substitution degree of 2.6 or less, and the ratio of the grafted hydroxy acid component is 0 on average in terms of hydroxy acid with respect to 1 mol of glucose unit constituting the glucan derivative. 2. The modified glucan derivative according to claim 1, which is 2 to 4 mol. The modified glucan derivative according to claim 1, wherein the hydroxy acid component is composed of at least one selected from α-hydroxy C _2-10 alkanecarboxylic acid and C _4-10 cyclic diester.   The modified glucan derivative according to claim 1, wherein the average polymerization degree of the graft chain is 2 to 12 in terms of hydroxy acid.   The modified glucan derivative according to claim 1, wherein the graft chain has an average degree of polymerization of 2 to 11 and an average molecular weight of 900 or less in terms of hydroxy acid. The glucan derivative is cellulose C _2-4 acylate having an average degree of substitution of 2 to 2.95, the hydroxy acid component is at least composed of lactic acid and / or lactide, and the proportion of the grafted hydroxy acid component constitutes the glucan derivative The average of the graft chain is 2.5 to 10.5 in terms of hydroxy acid and the average molecular weight of the graft chain is 800 with respect to 1 mol of glucose unit. The modified glucan derivative according to claim 1, which is:   An optical molded body formed from the modified glucan derivative according to claim 1.   The optical molded body according to claim 8, which is an optical film.