JP2009091543A - Method for producing cellulose acetate derivative and new cellulose acetate derivative - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for industrially efficiently producing a cellulose acetate derivative having a high substitution degree and excellent in various characteristics, particularly optical characteristics. <P>SOLUTION: In the method for producing a cellulose acetate derivative, cellulose acetate having a total substitution degree of acetyl groups of 1.5-2.9 is allowed to react with a modifier reactive with a hydroxyl group, whereby a modifying group corresponding to the modifier is introduced into a hydroxyl group in the 6-position of a glucose skeleton to produce a cellulose acetate derivative having a higher substitution degree, wherein when the number of moles of water contained in the reaction system at the time of reaction initiation is denoted by x, the number of moles of hydroxyl groups in the 6-positions of the glucose skeletons of the cellulose acetate as a starting material is denoted by y, and the total number of moles of hydroxyl groups in the 2- and 3-positions of the glucose skeletons of the cellulose acetate is denoted by z, the modifier is used in a range from more than x moles to not more than (x+y+0.5z) moles to preferentially introduce the modifying group into a hydroxyl group in the 6-position of a glucose skeleton. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a method for producing a cellulose acetate derivative having a high degree of substitution useful as a raw material such as an adsorbent, a film, an optical isomer separating agent, particularly a photographic material or an optical material, and an aromatic acyl group is selectively selected at the 6-position. The present invention relates to a novel cellulose acetate derivative introduced in 1.

  Cellulose derivatives are known in which a plurality of modifying groups (for example, acetyl groups and modified groups other than acetyl groups) are introduced into the hydroxyl groups of cellulose. For example, Japanese Unexamined Patent Application Publication No. 2002-322201 discloses a cellulose mixed acid ester compound in which a hydrogen atom of a hydroxyl group of cellulose is substituted with a substituted or unsubstituted aromatic acyl group and a substituted or unsubstituted aliphatic acyl group. It is disclosed that according to this cellulose mixed acid ester compound, a film excellent in optical isotropy, transparency, water resistance, and dimensional stability can be formed. In the examples of this document, cellulose benzoate trifluoroacetate and the like are synthesized.

Japanese Patent Application Laid-Open No. 2006-328298 discloses an optical film formed by melting a composition mainly composed of cellulose ester, wherein the cellulose ester satisfies the following formulas (1) and (2). Is disclosed.
Formula (1) 2.4 <= X + Y <= 2.9
Formula (2) 0.3 <= Y <= 1.5
(Wherein X represents the degree of substitution with acetic acid and Y represents the degree of substitution with aromatic carboxylic acid)
In the examples of this document, cellulose is used as a raw material, and two kinds of carboxylic acids are reacted with this to synthesize cellulose mixed acylate such as cellulose acetate benzoate. However, this reaction is a reaction under heterogeneous conditions, and the reaction does not proceed uniformly. In addition, it is considered that the more reactive carboxylic acid reacts on the cellulose surface, and then the less reactive carboxylic acid reacts. Furthermore, the cellulose ester derivative to be produced is a composition having a large variation between molecules, such as a derivative rich in acetyl group or a derivative rich in benzoyl group. As a result, the solubility in the solvent differs among the products, causing phase separation or turbidity when used as a dope, difficult to filter, unable to filter, and increasing intermolecular substitution degree distribution. A composition having is obtained.

  Japanese Patent Application Laid-Open Nos. 2007-199392 and 2007-199391 disclose cellulose acylate films having specific optical characteristics. However, although these documents have obtained a high degree of benzoyl group substitution at the 6-position of the glucose skeleton, the cellulose acylate having a high total substitution degree and a rich introduction of an acyl group other than an acetyl group at the 6-position. The rate has not been obtained.

JP 2002-322201 A JP 2006-328298 A JP 2007-199392 A JP 2007-199391 A

  An object of the present invention is to provide a method for industrially efficiently producing a cellulose acetate derivative having various properties, particularly optical properties, and a high degree of substitution. Another object of the present invention is to provide a novel cellulose acetate derivative excellent in various properties, particularly optical properties.

  As a result of intensive studies to achieve the above object, the present inventors have determined that the amount of water in the reaction system and each position of the glucopyranose skeleton are added to cellulose acetate having an acetyl group total substitution degree of 1.5 to 2.9. When a hydroxyl-reactive modifier in an amount that takes into account the amount of hydroxyl groups is reacted, a modifying group corresponding to the modifier is selectively introduced into the hydroxyl group at the 6-position of the glucopyranose skeleton, and the cellulose acetate thus obtained The derivative was found to have excellent optical properties, and the present invention was completed.

  That is, in the present invention, a cellulose acetate having a total substitution degree of acetyl group of 1.5 to 2.9 is reacted with a hydroxyl group reactive modifier, and the hydroxyl group at the 6-position of the glucose skeleton is modified corresponding to the modifier. A method for producing a cellulose acetate derivative having a higher degree of substitution by introducing a group, wherein x is the number of moles of water contained in the reaction system at the start of the reaction, and the hydroxyl group at the 6-position of the glucose skeleton of the raw material cellulose acetate Where y is the number of moles and z is the total number of hydroxyl groups at the 2nd and 3rd positions of the glucose skeleton of the raw material cellulose acetate, the modifier is used in a range of more than x moles and not more than (x + y + 0.5z) moles. And providing a method for producing a cellulose acetate derivative, wherein the modifying group is selectively introduced into the hydroxyl group at the 6-position of the glucose skeleton.

  As the modifying agent, a compound selected from carboxylic acid, carboxylic acid halide, carboxylic acid anhydride and isocyanate compound can be used.

  In the production method, after reacting the modifying agent, another modifying agent may be reacted with the reaction product to introduce a modifying group corresponding to the modifying agent into at least a part of the remaining hydroxyl groups.

  In the present invention, the total substitution degree of the acetyl group is 1.5 to 2.9, and the substitution degree of the acyl group other than the acetyl group at the 6-position is the substitution degree of the acyl group other than the acetyl group at the 2-position and the 3-position. A cellulose acetate derivative characterized by being larger than the sum is provided. In this cellulose acetate derivative, the acyl group substitution degree other than the acetyl group at the 6-position is preferably 1.5 times or more the sum of the substitution degree of acyl groups other than the acetyl group at the 2-position and the 3-position. The acyl group other than the acetyl group may be an aromatic acyl group or a propionyl group.

In addition, the total substitution degree of each acyl group of the cellulose acetate derivative used as a raw material and the product can be measured by a conventional method such as ¹ H-NMR method or ¹³ C-NMR method. The substitution degree distribution of each acyl group (substitution degree at the 2nd, 3rd and 6th positions of the glucose skeleton) can be measured by a known method such as ¹³ C-NMR method. Regarding the measurement method, the method of Tezuka (Tezuka, Carbohydr. Res., 273, 83 (1995)) and JP-A-2002-338601 can be referred to.

  According to the production method of the present invention, since cellulose acetate which is easily dissolved in an organic solvent having an acetyl group total substitution degree of 1.5 to 2.9 is used as a raw material, an acylation reaction or the like can be performed in a homogeneous system. Compared with the case where cellulose is used as a raw material, the reaction rate can be remarkably increased, and a cellulose acetate derivative having a uniform degree of substitution between molecules can be efficiently produced. In addition, the amount of modifier used is determined in consideration of the amount of water in the reaction system at the start of the reaction and the amount of hydroxyl groups at the 2nd, 3rd and 6th positions of the glucose skeleton of the raw cellulose acetate. The modifying group (for example, benzoyl group) can be introduced in a regioselective manner, that is, in a highly selective manner at the 6-position of the glucose skeleton. Moreover, after making a modifier react, a desired modifier group can be introduce | transduced into a desired position by making another modifier react with a reaction product. Moreover, according to the production method of the present invention, a novel cellulose acetate derivative in which an aromatic acyl group is selectively introduced into the hydroxyl group at the 6-position can be produced industrially efficiently.

  The present invention also provides a novel cellulose acetate derivative in which an aromatic acyl group is selectively introduced into the 6-position hydroxyl group. This cellulose acetate derivative is excellent in various properties, particularly optical properties, for example, properties related to orientation birefringence and photoelastic coefficient when stretched into a film, and thus can be used as an optical material or the like.

  [Production of cellulose acetate derivative]

  In the method for producing a cellulose acetate derivative of the present invention, a hydroxyl group-reactive modifier is reacted with cellulose acetate having an acetyl group total substitution degree of 1.5 to 2.9, and the modification is made to the hydroxyl group at the 6-position of the glucose skeleton. A cellulose acetate derivative having a higher degree of substitution is produced by introducing a modifying group corresponding to the agent.

  In the present invention, since cellulose acetate having a total substitution degree of acetyl group of 1.5 to 2.9 is used as a raw material, the raw material is easily dissolved in an organic solvent, and a modification group introduction reaction such as an acylation reaction is performed in a homogeneous system. Can do. Therefore, compared with the case where a modifying group is introduced using cellulose as a raw material, variation in the distribution of substitution degree between molecules can be reduced, and a cellulose acetate derivative having a uniform substitution degree distribution can be obtained. The total degree of acetyl group substitution of cellulose acetate used as a raw material is preferably 1.7 to 2.7, more preferably 1.9 to 2.5.

  The hydroxyl-reactive modifier may be any modifier that is reactive with a hydroxyl group, and examples thereof include carboxylic acid, carboxylic acid halide, carboxylic acid anhydride, and isocyanate compound.

  Carboxylic acids include aliphatic carboxylic acids, aromatic carboxylic acids, alicyclic carboxylic acids, and the like. These carboxylic acids may have a substituent. Examples of the substituent include a halogen atom, a cyano group, a hydroxyl group, a nitro group, a silyl group, a silyloxy group, and an alkyl group having 1 to 12 carbon atoms (methyl, ethyl, propyl, isopropyl, butyl, t-butyl group, etc.) , C1-C12 alkoxy groups (methoxy, ethoxy, propoxy groups, etc.), C6-C20 aryl groups (phenyl, naphthyl groups, etc.), C6-C20 aryloxy groups (phenyloxy, naphthyloxy) Group), C1-C20 acyl group (acetyl, propionyl, benzoyl group, etc.), C1-C20 substituted or unsubstituted carbamoyl group, C1-C20 substituted or unsubstituted carbamoyloxy group, carbon A sulfamoyl group having 1 to 20 carbon atoms, a sulfamoyloxy group having 1 to 20 carbon atoms, a phosphino group, a phosphinyl group, a phosphono group Phosphinyloxy group, phosphonooxy group, phosphinylamino group, phosphonoamino group, ureido group having 1 to 20 carbon atoms, carboxyl group, substituted oxycarbonyl group having 1 to 20 carbon atoms (alkoxycarbonyl group, aryloxycarbonyl group) And an aralkyloxycarbonyl group).

  Representative examples of carboxylic acids include aliphatic carboxylic acids that may have a substituent such as acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, (meth) acrylic acid, cinnamic acid, and trifluoroacetic acid. Acid; benzoic acid, 1-naphthylcarboxylic acid, 2-naphthylcarboxylic acid, m-methylbenzoic acid, p-methylbenzoic acid, m-methoxybenzoic acid, p-methoxybenzoic acid, 3,5-dimethoxybenzoic acid, 3 , 4,5-trimethoxybenzoic acid, 2,4,6-trimethylbenzoic acid, m-cyanobenzoic acid, p-cyanobenzoic acid, m-chlorobenzoic acid, p-chlorobenzoic acid, m-fluorobenzoic acid, p -Fluorobenzoic acid, 2,5-dichlorobenzoic acid, p-acetylbenzoic acid, p-phenylbenzoic acid, p-formylbenzoic acid, pt-butylbenzoic acid, p-butoxy Benzoic acid, m-acetoxybenzoic acid, p-acetoxybenzoic acid, m-methoxycarbonylbenzoic acid, p-methoxycarbonylbenzoic acid, m-benzyloxybenzoic acid, p-benzyloxybenzoic acid, p-cyclohexylbenzoic acid, p -Methanesulfonylaminobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, m-acetaminobenzoic acid, p-acetaminobenzoic acid, m-benzoylaminobenzoic acid, p-benzoylaminobenzoic acid, m-benzoyloxybenzoic acid Acid, p-benzoyloxybenzoic acid, m-benzylbenzoic acid, p-benzylbenzoic acid, m- (N-phenylcarbamoyloxy) benzoic acid, p- (N-phenylcarbamoyloxy) benzoic acid, p- (ethoxycarbonyl) Amino) benzoic acid, p-methylthiobenzoic acid, p- An aromatic carboxylic acid which may have a substituent such as enylthiobenzoic acid, p-hydroxybenzoic acid, p- (4-pyridyl) benzoic acid; a fat which may have a substituent such as cyclohexanecarboxylic acid And cyclic carboxylic acids.

  Carboxylic acid halides include carboxylic acid chlorides and carboxylic acid bromides corresponding to the carboxylic acids. The carboxylic acid anhydride includes a carboxylic acid anhydride corresponding to the carboxylic acid.

  The isocyanate compound includes aromatic isocyanate, aliphatic isocyanate, alicyclic isocyanate and the like. These isocyanates may have a substituent. Examples of the substituent include the same substituents as the substituent that the carboxylic acid may have.

  As typical examples of the isocyanate compound, for example, phenyl isocyanate, 1-naphthyl isocyanate, 2-naphthyl isocyanate, 2-methylphenyl isocyanate, 3-methylphenyl isocyanate, 4-methylphenyl isocyanate, 3,5-dimethylphenyl isocyanate, 2-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, 4-chlorophenyl isocyanate, 2-methoxyphenyl isocyanate, 3-methoxyphenyl isocyanate, 4-methoxyphenyl isocyanate, 2-nitrophenyl isocyanate, 3-nitrophenyl isocyanate, 4-nitrophenyl isocyanate Aromatic isocyanates such as methyl isocyanate, ethyl isocyanate, butyl isocyanate And aliphatic isocyanates such as bets and the like.

  The modifying group introduced into the 6-position hydroxyl group is a corresponding acyl group when the modifying agent is a carboxylic acid, a carboxylic acid halide or a carboxylic anhydride, and when the modifying agent is an isocyanate compound, the corresponding substituted carbamoyl It is a group. For example, when the modifying agent is acetic acid, acetic acid chloride or acetic anhydride, the modifying group to be introduced is an acetyl group, and when the modifying agent is benzoic acid, benzoic acid chloride or benzoic anhydride, the modifying group to be introduced is When it is a benzoyl group and the modifying agent is phenyl isocyanate, the modifying group to be introduced is a phenylcarbamoyl group.

  An important feature of the present invention is that x is the number of moles of water contained in the reaction system at the start of the reaction, y is the number of moles of the hydroxyl group at the 6-position of the glucose skeleton of the raw cellulose acetate, and 2 of the glucose skeleton of the raw cellulose acetate. When the total number of moles of the hydroxyl group at the position and the 3-position is z, the modifier is used in the range of more than x moles and not more than (x + y + 0.5z) moles. Considering the amount of water in the system for deactivating the modifier, the amount of modifier used is within the above range, so that the desired modifying group can be selectively added to the hydroxyl group at the 6-position of the glucose skeleton and the desired amount. Can be introduced.

  The amount of the modifier used is preferably in the range of (x + 0.1y) mol or more and (x + y + 0.2z) mol or less. Moreover, the range of (x + 0.1y) mol or more and (x + 1.2y) mol or less is also preferable. By selecting the amount of the modifier used within the above range, the amount of the modifier introduced into the 6-position hydroxyl group can be adjusted.

  When the raw material cellulose acetate and a hydroxyl group-reactive modifier are reacted, a modifying group corresponding to the modifying agent is preferentially introduced into the hydroxyl group at the 6-position of the glucose skeleton of cellulose acetate. Thereafter, the remaining hydroxyl groups (remaining hydroxyl groups at the 6-position, hydroxyl groups at the 2-position and the 3-position) are subjected to another modification to the reaction product (after post-treatment as necessary and isolation of the reaction product). An agent (second modifier) can be reacted to introduce a modifying group corresponding to the second modifier. By selecting the amount of the second modifier used, the amount of the modifier introduced can be adjusted.

  For example, the raw material cellulose acetate is reacted with an aromatic acylating agent (aromatic carboxylic acid, aromatic carboxylic acid halide or aromatic carboxylic acid anhydride) as a modifier, and an aromatic acyl is added to the hydroxyl group at the 6-position of the glucose skeleton. By selectively introducing a group (such as a benzoyl group), a cellulose acetate derivative rich in the 6-position aromatic acyl group can be obtained. In addition, the raw material cellulose acetate is reacted with an aromatic acylating agent as a first modifying agent to selectively introduce an aromatic acyl group (such as a benzoyl group) into the hydroxyl group at the 6-position of the glucose skeleton. An aliphatic acylating agent (aliphatic carboxylic acid, aliphatic carboxylic acid halide, or aliphatic carboxylic acid anhydride) as a modifier of the amino acid, and an aliphatic acyl group (acetyl group) on the 2nd and 3rd hydroxyl groups of the glucose skeleton Etc.), a highly substituted cellulose acetate derivative rich in the 6-position aromatic acyl group can be obtained. Furthermore, after reacting a raw material cellulose acetate with an aliphatic acylating agent as a first modifier and selectively introducing an aliphatic acyl group (such as an acetyl group) into the hydroxyl group at the 6-position of the glucose skeleton, By reacting an aromatic acylating agent as a modifying agent and introducing an aromatic acyl group (such as a benzoyl group) into the 2- and 3-position hydroxyl groups of the glucose skeleton, the 2- and 3-position aromatic acyl groups are rich. A highly substituted cellulose acetate derivative can be obtained.

  In this way, by selecting the usage amount of the first modifying agent (first modifying agent) and the usage amount of another modifying agent (second modifying agent) to be used next if necessary, The degree of substitution (the degree of substitution of the modifying group corresponding to the first modifying agent, the degree of substitution of the modifying group corresponding to the second modifying agent, and the total degree of substitution) and the distribution of substituents can be controlled.

  In the reaction between cellulose acetate and the modifier, the reaction solvent is not particularly limited as long as it is a solvent that is excellent in the solubility of raw materials and products and does not inhibit the reaction, and can be appropriately selected depending on the type of raw materials. Examples of such solvents include ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and isophorone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and methyl formate; pyridine, N, N-dimethylformamide, Nitrogen-containing compounds such as N, N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, nitromethane; ethers such as tetrahydrofuran, dioxane, dioxolane (cyclic ethers, chain ethers); methylene chloride, chloroform, dichloroethane, tetrachloroethane And halogenated hydrocarbons such as carbon tetrachloride; sulfur-containing compounds such as dimethyl sulfoxide. Among these, pyridine, methylene chloride, chloroform, and cyclohexanone are preferable from the viewpoint of solubility of raw materials and products, and pyridine is particularly preferable. A solvent can be used individually or in combination of 2 or more types.

  The concentration of the raw material cellulose acetate used in the reaction can be appropriately selected in consideration of solubility, reaction efficiency, etc., but is generally about 2 to 50% by weight, preferably about 5 to 20% by weight.

  In the production method of the present invention, there is no particular limitation on the method of adding a modifier (carboxylic acid, carboxylic acid halide, carboxylic acid anhydride, isocyanate compound, etc.) to the reaction system, and it may be added all at once. In order to control the reaction, it is preferable to add sequentially (added continuously or intermittently).

  If necessary, a base may be added to the reaction system in order to promote the reaction and capture the generated hydrogen halide and the like. Examples of the base include nitrogen-containing aromatic compounds such as pyridine and dimethylaminopyridine, tertiary amines such as triethylamine, tri-n-butylamine and tri-propylamine, and inorganic bases. Pyridine and the like can be used as a solvent as described above. Moreover, when using carboxylic acid as a modifier, an acid catalyst such as sulfuric acid or perchloric acid may be added to the reaction system.

  The reaction temperature varies depending on the type of raw material, but is usually 0 to 150 ° C, preferably about 30 to 130 ° C.

  By the above reaction, a cellulose acetate derivative in which a modifying group (for example, acyl group, substituted carbamoyl group, etc.) corresponding to the modifying agent used for the hydroxyl group at the 6-position of the glucose skeleton of the raw material cellulose acetate is selectively introduced in a desired amount is obtained. Generate. As described above, another modifying group can be similarly introduced into the remaining hydroxyl groups.

  After completion of the reaction, alcohol is added to the reaction mixture, and the remaining excess modifiers (acid halide, acid anhydride, isocyanate compound, etc.) with high reactivity are extremely low in reactivity and soluble in water and organic solvents. Is preferably converted to an ester having a high molecular weight. By converting the excess modifier to an ester in this way, impurities derived from the modifier, for example, compounds having low solubility in water or organic solvents such as carboxylic acid which is a hydrolysis product of the modifier, other It is possible to prevent troubles such as coloring and white turbidity of the product due to impurities, interference of function expression, mixing of impurities into the product, etc., and it is possible to industrially efficiently obtain high purity and high quality cellulose acetate derivatives. Become.

  Examples of the alcohol include methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-butanol, isobutyl alcohol, s-butyl alcohol, t-butyl alcohol, pentanol, 2-pentanol, 3-pentanol, hexanol, Monohydric alcohols such as octanol, cyclopentyl alcohol, cyclohexyl alcohol, and benzyl alcohol; polyhydric alcohols such as ethylene glycol and glycerin can be used. Among these, alcohols having 1 to 5 carbon atoms such as methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-butanol, t-butyl alcohol, pentanol, 2-pentanol, and 3-pentanol are preferable.

  The amount of alcohol used may be an amount necessary for esterifying all of the remaining excess modifier. For example, 1 to 20 mol, preferably 1. About 5 to 10 moles. If the amount of alcohol is too small, the modifying agent may remain without being completely esterified, and if the amount of alcohol is too large, the produced cellulose acetate derivative may precipitate. When the cellulose acetate derivative is precipitated at this stage, impurities are easily taken in. Therefore, the esterification reaction of the remaining modifier is preferably carried out under a condition that does not precipitate the produced cellulose acetate derivative (in a homogeneous system).

  The reaction temperature in the reaction between the alcohol and the remaining excess modifier can be appropriately selected according to the cellulose acetate derivative as the target product and the type of alcohol to be added. In order to suppress the transesterification reaction with the added alcohol, it is usually 80 ° C. or lower, preferably 60 ° C. or lower, more preferably 50 ° C. or lower. The minimum of reaction temperature should just be a temperature which does not impair progress of reaction, for example, 30 degreeC, Preferably it is 40 degreeC. The reaction time varies depending on the reaction temperature and the like, but is generally about 0.1 to 12 hours, preferably about 0.1 to 3 hours.

  From the reaction mixture after the reaction between the raw material cellulose acetate and the modifying agent, if necessary, esterify the modifying agent such as excess acylating agent as described above, and then separate the cellulose acetate derivative as the target product. . The method for separating cellulose acetate is not particularly limited. For example, precipitation, crystallization, filtration, washing, drying, extraction, concentration, column chromatography and the like can be used alone or in appropriate combination of two or more. A method of separating the cellulose acetate derivative by precipitation (including reprecipitation) is particularly preferable in terms of properties, purification efficiency, and the like. The precipitation operation is performed by mixing the solution containing the cellulose acetate derivative with the poor solvent, such as pouring the solution containing the produced cellulose acetate derivative into the poor solvent of the cellulose acetate derivative. Examples of the solvent for the solution containing the cellulose acetate derivative (good solvent for the cellulose acetate derivative) include, for example, nitrogen-containing heterocyclic compounds such as pyridine, ketones such as acetone, halogenated hydrocarbons such as methylene chloride, esters, ethers, amides, Examples include aprotic polar solvents. These solvents can be used alone or in combination of two or more. As the solvent, nitrogen-containing heterocyclic compounds such as pyridine, ketones such as acetone, and halogenated hydrocarbons such as methylene chloride are particularly preferable.

  The poor solvent of the cellulose acetate derivative may be a solvent having a low solubility of the cellulose acetate derivative. For example, methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-butanol, t-butyl alcohol, pentanol, 2-pen Examples thereof include alcohols having 1 to 5 carbon atoms such as tanol and 3-pentanol (particularly monohydric alcohols); water; aliphatic hydrocarbons such as hexane; alicyclic hydrocarbons such as cyclohexane. These solvents can be used alone or in combination of two or more. Examples of a combination of two or more solvents include a mixed solution of two or more types of alcohol having 1 to 5 carbon atoms, a mixed solution of alcohol having 1 to 5 carbon atoms and water, and the like. As the poor solvent, alcohol having 1 to 5 carbon atoms is particularly preferable.

  The amount of the poor solvent used in the precipitation operation is, for example, 50 to 20000 parts by weight, preferably 100 to 10,000 parts by weight, and more preferably 150 to 1000 parts by weight with respect to 100 parts by weight of the cellulose acetate derivative solution. . If the amount of the poor solvent is too small, it may be difficult to efficiently obtain a high-quality cellulose acetate derivative. Conversely, if the amount of the poor solvent is too large, it is economically disadvantageous.

  The precipitated cellulose acetate derivative is subjected to solid-liquid separation operations such as filtration and centrifugation, and the obtained solid is subjected to reprecipitation as necessary, followed by drying to obtain high-purity and high-quality cellulose. An acetate derivative can be obtained.

  As a method for purifying cellulose acetate derivatives, cellulose acetate derivative powders (for example, those obtained by the above-described precipitation operation), cellulose acetate derivatives are difficult to dissolve, and are produced by the reaction of modifiers such as acylating agents with alcohol. A method of washing (extracting) the ester and other impurities with a solvent that is easily dissolved is also preferred. As such a solvent, the solvent illustrated as a poor solvent of the said cellulose acetate derivative is mentioned. Among these, the said C1-C5 alcohol is preferable.

  According to the production method of the present invention, the total degree of substitution with substituents (modifying groups) is 1.6 to 3.0, the total degree of substitution with acetyl groups is 1.5 to 2.9, and the total degree of substitution with substituents other than acetyl groups. 0.1-1.5, the substitution degree at the 2-position is 0.5-1.0, the substitution degree at the 3-position is 0.5-1.0, and the substitution degree at the 6-position is 0.5-1.0. A cellulose acetate derivative can be obtained.

  In addition, as described above, an acylating agent other than the acetylating agent (aromatic acylating agent, propionylating agent, etc.) is used as the first modifying agent, and aliphatic acylation is used as the second modifying agent as necessary. Cellulose acetate derivatives rich in acyl groups other than acetyl groups (aromatic acyl groups, propionyl groups, etc.) (highly substituted cellulose rich in 6-position aromatic acyl groups, etc.) by using agents (acetylating agents, etc.) Acetate derivatives). In addition, an aliphatic acylating agent (such as an acetylating agent) is used as the first modifying agent, and an acylating agent other than the acetylating agent (such as an aromatic acylating agent or a propionylating agent) is used as the second modifying agent. Thus, a highly substituted cellulose acetate derivative rich in acyl groups other than the acetyl group (aromatic acyl group, propionyl group, etc.) at the 2- and 3-positions can be obtained. As the acyl group other than the acetyl group, an aromatic acyl group or a propionyl group is preferable, and an aromatic acyl group is particularly preferable.

  In cellulose acetate derivatives rich in acyl groups other than the 6-position acetyl group (aromatic acyl group, propionyl group, etc.), the total degree of acetyl group substitution is 1.5 to 2.9, and other than the acetyl group in the 6-position The degree of substitution of acyl groups (aromatic acyl groups, propionyl groups, etc.) is preferably greater than the sum of substitution degrees of acyl groups (aromatic acyl groups, propionyl groups, etc.) other than acetyl groups at the 2-position and 3-position. The substitution degree of the aromatic acyl group at the 6-position is 1.5 times or more, especially 1.7 times or more of the sum of the substitution degree of acyl groups other than the acetyl group at the 2-position and the 3-position (aromatic acyl group, propionyl group, etc.) It is more preferable that The substitution degree of acyl groups other than the acetyl group at the 6-position (aromatic acyl group, propionyl group, etc.) is, for example, about 0.10 to 0.40, preferably about 0.15 to 0.35, and the 2nd and 3rd positions. The degree of substitution with an acyl group other than the acetyl group (aromatic acyl group, propionyl group, etc.) is, for example, about 0 to 0.12, preferably about 0 to 0.09.

  In the highly substituted cellulose acetate derivative rich in acyl groups (aromatic acyl group, propionyl group, etc.) other than the 2- and 3-position acetyl groups, the acyl group total substitution degree is 1.6 to 3.0, The degree of substitution is preferably 1.5 to 2.9, and the acyl group other than the acetyl group (aromatic acyl group, propionyl group, etc.) and the total degree of substitution is preferably 0.1 to 1.5. The total degree of substitution with an acyl group is preferably 2.8 to 3.0, more preferably 2.9 to 3.0. The total degree of substitution with an acetyl group is preferably 1.8 to 2.8, more preferably 2.2 to 2.7. The total substitution degree of acyl groups other than acetyl groups (aromatic acyl groups, propionyl groups, etc.) is preferably 0.2 to 1.2, more preferably 0.3 to 0.8. In addition, the sum of the substitution degree of the acyl group other than the acetyl group (aromatic acyl group, propionyl group, etc.) at the 2nd and 3rd positions is substituted with the acyl group other than the acetyl group (aromatic acyl group, propionyl group etc.) at the 6th position It is preferably 2.5 times or more, more preferably 3.0 times or more with respect to the degree. The degree of acyl group substitution at the 2-position, the degree of acyl group substitution at the 3-position, and the degree of acyl group substitution at the 6-position are usually in the range of 0.9 to 1.0, respectively. Moreover, the sum of substitution degree of acyl groups (aromatic acyl group, propionyl group, etc.) other than the acetyl group at the 2-position and 3-position is usually 0.1 to 1.0, preferably 0.15 to 0.7, Preferably it is about 0.2-0.5. Furthermore, substitution degree of acyl groups other than the acetyl group at the 6-position (aromatic acyl group, propionyl group, etc.) is usually 0 to 0.5, preferably 0 to 0.3, more preferably 0 to 0.2 (for example, 0.01 to 0.2). The degree of substitution at the 6-position with an acetyl group is usually 0.5 to 1.0, preferably 0.7 to 1.0, and more preferably 0.8 to 1.0.

  Since the production method of the present invention does not require a sulfuric acid catalyst, the production of low molecular weight components can be suppressed, the molecular weight distribution can be reduced, and coloring of the product can be reduced. For example, by the method of the present invention, a cellulose mixed acylate having a coloring degree of 200 or less, more preferably 150 or less, and further preferably 100 or less in terms of the Hazen unit color number can be obtained.

  The cellulose acetate derivative obtained by the method of the present invention can be used as a material such as a fiber, an adsorbent, a film (particularly an optical film), an optical isomer separating agent, or the like, as it is or further derivatized. Moreover, the function can be changed or a new function can be added by adding this cellulose acetate derivative or further its derivative to another substance or material.

  In particular, the cellulose acetate derivative rich in the 6-position aromatic acyl group and the highly substituted cellulose acetate derivative rich in the 2-position and 3-position aromatic acyl groups have optical properties such as orientation birefringence when stretched into a film. And is excellent in the properties relating to the photoelastic coefficient, it can be suitably used as an optical material or the like. This will be described below.

  In the cellulose acetate derivative in which an aromatic acyl group is introduced into the hydroxyl group of the glucopyranose ring, when the polymer chain is oriented by stretching, it is bonded to the 2nd and 3rd positions bonded to the glucopyranose ring only through the oxygen atom. It is considered that the aromatic ring of the introduced aromatic acyl group is arranged in a direction orthogonal to the polymer chain, and the polarizability due to the aromatic ring faces in the direction orthogonal to the polymer chain. Therefore, it is considered that the aromatic acyl group introduced into the 2nd and 3rd positions acts to make the orientation birefringence of the cellulose mixed acylate negative. On the other hand, the aromatic ring of the aromatic acyl group introduced at the 6-position bonded to the glucopyranose ring via the methyleneoxy group is highly flexible, so it is oriented in the same direction as the polymer chain, resulting from the aromatic ring The polarizability is considered to be in the direction parallel to the polymer chain. Therefore, it is considered that the aromatic acyl group introduced at the 6-position acts to make the orientation birefringence of the cellulose mixed acylate positive. Therefore, the highly substituted cellulose acetate derivative rich in the 2-position and 3-position aromatic acyl groups, in which the aromatic acyl group is relatively rich in the 2-position and 3-position as compared with the 6-position, is a polymer chain. A material having a high polarizability in a direction orthogonal to the direction, and a direction showing a large birefringence is orthogonal to the stretching direction of the film (negative orientation birefringence). In addition, the cellulose acetate derivative rich in 6-position aromatic acyl group in which the aromatic acyl group is relatively rich in the 6-position as compared with the 2-position and 3-position has a high polarizability along the polymer chain. The direction in which the film becomes a material and exhibits large birefringence is the film stretching direction (positive orientation birefringence). By blending a material having a positive orientation birefringence and a material having a negative orientation birefringence at an appropriate ratio, the orientation birefringence of the retardation film can be controlled. The distribution of the substitution positions of the aromatic acyl group is considered to affect the photoelastic birefringence. As described above, see Sadao Fujii, “Required Properties and Material Design of Polymer Phase Retardation Film”, “Liquid Crystal”, Vol. 9, No. 4, 2005, pages 227 to 236. Therefore, the cellulose acetate derivative of the present invention is useful as a raw material for a retardation film and a protective film for a polarizing film.

  In the cellulose acetate derivative of the present invention, the sulfate group content is, for example, 200 ppm by weight or less (for example, 1 to 200 ppm by weight), preferably 150 ppm by weight or less (for example, 1 to 150 ppm by weight) based on the cellulose acetate derivative. ), More preferably 100 ppm by weight or less (for example, 1 to 100 ppm by weight), and particularly preferably 50 ppm by weight or less (for example, 1 to 50 ppm by weight). If a large amount of sulfate radicals remain, problems such as yellowing of the product color may occur when the product is dried or changes with time. In addition, there is a possibility of causing a functional inhibition.

The sulfate radical here means the total quantity of sulfate radicals present in the cellulose mixed acylate in the form of bound sulfuric acid, unbound sulfuric acid, sulfate, sulfate ester, sulfate complex, and the like. The content of sulfate radicals in the cellulose mixed acylate was determined by calcining an absolutely dry sample (cellulose mixed acylate) in an electric furnace at 1300 ° C, trapping the sublimed sulfurous acid gas in 10% by weight hydrogen peroxide, and measuring the coulometry. It can be measured by quantifying by a method (SO ₄ ^2- converted value). The unit is ppm by weight with respect to cellulose mixed acylate. The analysis conditions of the coulometric titration method are as follows. As an apparatus used for the coulometric titration method, for example, trade name “TOX-10Σ” manufactured by Mitsubishi Chemical Corporation may be mentioned.
Temperature: 1100 ° C
Sample amount: 20 ± 2mg
Combustion gas: Oxygen gas (99.7% or more)
Aeration rate: argon 200 ml / min, oxygen 150 ml / min
Combustion tube: quartz glass tube (inner tube inner diameter 13 mm, outer tube inner diameter 22 mm)

  According to the production method of the present invention, since it is not necessary to use sulfuric acid, it is possible to obtain a cellulose mixed acylate having a very low sulfate radical content as described above.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, “2-position Ac group” is 2-position acetyl group substitution degree, “3-position Ac group” is 3-position acetyl group substitution degree, and “6-position Ac group” is 6-position acetyl group substitution. “2-position Pr group” is the 2-position propionyl group substitution degree, “3-position Pr group” is the 3-position propionyl group substitution degree, “6-position Pr group” is the 6-position propionyl group substitution degree, “2-position Pr group” “Bz group” represents the degree of substitution of the benzoyl group at the 2-position, “3-position Bz group” represents the degree of substitution of the benzoyl group at the 3-position, and “6-position Bz group” represents the degree of substitution of the benzoyl group at the 6-position. “Ppm” means chemical shift or weight ppm.

In addition, the measurement of the substitution degree of the acyl group (DS), the substitution degree of the 2-position of the glucose skeleton (DS2), the substitution degree of the 3-position of the glucose skeleton (DS3), and the substitution degree of the 6-position of the glucose skeleton (DS6) It carried out as follows. The measurement conditions are as shown below.
Measuring equipment: AVANCE600 manufactured by Bruker
Measurement mode: ¹ H-NMR, ¹³ C-NMR
Measuring solvent: deuterated chloroform (with TMS)
Measurement temperature: 40 ° C
The substituent distribution is determined from the signal of the carbonyl group into which the acyl group has been introduced. The shape of the signal changes depending on the type of substituent, degree of substitution, and the position where the substituent is introduced. In addition, it is necessary to measure the cellulose acylate. Although the exact position specifying method differs depending on the degree of substitution and the substituent distribution, the numerical value of the substituent distribution in the present example is calculated as follows.
For example, in the case of cellulose acetate benzoate, in pyridine solvent sample, after propionylated with propionic anhydride, the ¹ H-NMR spectrum in deuterochloroform solvent was measured, after calculating a degree of substitution of each substituent group, ¹³ C- The NMR spectrum was measured, and the signal of benzoylcarbonyl carbon appearing in the vicinity of 164 to 167 ppm was indicated by a point as shown in FIG. 1 (indicated by Δ in the figure. Signal trough positions; around 164.9 ppm and around 165.5 ppm) ) And defined as the integrated intensity of each benzoylcarbonyl carbon at positions 2, 3, and 6 from the high magnetic field side. The degree of benzoyl substitution DSBzi (i is 2, 3 or 6) at the i-position of the glucose skeleton was determined from the following formula. DSBz represents the total degree of substitution of benzoyl groups.
DSBzi = DSBz * (i-position benzoylcarbonyl carbon signal integral intensity) / (sum of 2,3 and 6-position benzoylcarbonyl carbon signal integral intensity)

  Further, the degree of coloring was measured based on the color of JIS-K0071-1 chemical product. That is, the dope obtained by dissolving 2.4 g of the product in 40 mL of a mixed solvent of methylene chloride / methanol = 90/10 is put into a colorimetric tube, and colored by comparing with the reference color described in the JIS standard. The degree (number of Hazen unit colors) was measured.

Production Example 1
Wood pulp having an α-cellulose content of 97% was crushed and dried to a moisture content of 5%. The pulverized pulp was supplied to a pretreatment device, 25 parts by weight of glacial acetic acid per 100 parts by weight of α-cellulose was added to the pulp, and the mixture was mixed at 50 ° C. for 30 minutes to activate the cellulose.
The activated cellulose was transferred to a kneader-type acetylation apparatus, and 280 parts by weight of acetic anhydride and 450 parts by weight of glacial acetic acid which had been cooled to 10 ° C. in advance were added to the acetylation apparatus. Then 5 parts by weight of concentrated sulfuric acid was added and the whole mixture was mixed. Since heat accumulates in the contents of the reaction, acetylation is performed while controlling the temperature of the system by cooling so that the temperature of the system rises from the initial temperature of 10 ° C. to 68 ° C. over a period of 50 minutes at a substantially constant rate. The temperature of the system was maintained at 68 ° C. for 10 minutes.
To the system at 68 ° C., 24 parts by weight of 20 wt% magnesium acetate aqueous solution was added. The amount of magnesium acetate added was stoichiometrically excessive from the amount required for neutralization of sulfuric acid in the system. The completely neutralized mixture was transferred to an autoclave, and steam with a gauge pressure of 5 kg / cm ² was blown into the mixture while stirring the mixture and heated to 120 ° C. The mixture was kept at this temperature for 130 minutes for the first aging. The reaction mixture was quenched to 100 ° C. or lower, transferred to a precipitation tank equipped with a stirrer, and water was added to the tank. The produced cellulose acetate was precipitated, centrifuged to remove the solvent, transferred to a water washing tank, thoroughly washed with water in this tank, taken out of the tank and dried.
The obtained cellulose diacetate had a total acetyl group substitution degree of 2.19, a 2-position acetyl group substitution degree of 0.76, a 3-position acetyl group substitution degree of 0.79, and a 6-position acetyl group substitution degree of 0. .64.

Example 1 (Acylation of cellulose diacetate with benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 24.0 g (glucopyranose unit 0.094 mol) and pyridine 456.0 g (5.76 mol) were added, and the solution temperature was adjusted to 50 ° C. and dissolved. . Next, azeotropic dehydration was performed to distill 173.5 kg. After 129.2 g (1.64 mol) of pyridine was added to the system, the water content in the system was measured using a Karl Fischer moisture meter, and the water content in the system was 289 ppm. Subsequently, 6.32 g (0.045 mol) of benzoyl chloride was added dropwise over 23 minutes, the liquid temperature was adjusted to 40 ° C., and the mixture was aged for 5 hours while maintaining the temperature. After aging, the reaction solution was added to 1770.0 g of methanol for reprecipitation. The obtained fibrous solid was filtered, rinsed with methanol 150.0 g × 2 times, and then redissolved with 348.0 g of acetone. The solution was put into 1770.0 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with methanol (157.0 g × 2 times), and dried under reduced pressure overnight to obtain 25.9 g (yield: 92.7%) of cellulose acetate benzoate. It was. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.78, the 3-position Ac group: 0.78, the 6-position Ac group: 0.64, and the 2-position Bz group : 0.09, 3-position Bz group: 0.04, 6-position Bz group: 0.31. The coloring degree was 350 in terms of Hazen unit colors.

Example 2 (Acylation of cellulose diacetate with acetic anhydride and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 50.1 g (glucopyranose unit 0.20 mol) and pyridine 450.1 g (5.7 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 401.8 ppm. After adjusting the liquid temperature to 50 ° C. and adding 7.3 g (0.08 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the reaction solution was put into 2000.1 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 199.9 g of methanol, and then dried under reduced pressure in a vacuum dryer at 60 ° C. overnight. The dried fibrous solid was redissolved with 450.1 g (5.7 mol) of pyridine, and 38.0 g (0.27 mol) of benzoyl chloride was added dropwise thereto at room temperature over 30 minutes, and the liquid temperature was adjusted to 60 ° C. The mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or lower, and 8.7 g of methanol was added to treat the remaining benzoyl chloride. Subsequently, the reaction solution was added to 1999. 4 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 199.9 g of methanol, and redissolved with 800.2 g of acetone. The solution was poured into 4000.7 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 400.1 g of methanol, and dried under reduced pressure overnight to obtain 54.1 g (yield: 89.6%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.87, the 3-position Ac group: 0.81, the 6-position Ac group: 0.87, and the 2-position Bz group : 0.14, 3-position Bz group: 0.21, 6-position Bz group: 0.09. The coloring degree was 350 in terms of Hazen unit colors.

Example 3 (Acylation of cellulose diacetate with benzoyl chloride and acetic anhydride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 24.0 g (glucopyranose unit 0.09 mol) and pyridine 456.0 g (5.7 mol) were dissolved. This was azeotropically dehydrated, and 173.5 g of Py was distilled off. Thereafter, 129.2 g of Py was added to the system, and the water content in the system was measured using a Karl Fischer moisture meter. The water content in the system was 289 ppm. The liquid temperature was adjusted to 25 ° C., and 6.3 g (0.045 mol) of benzoyl chloride was added dropwise over 30 minutes, and then the liquid temperature was adjusted to 40 ° C. and aged for 5 hours while maintaining the temperature. Subsequently, 6.39 g (0.06 mol) of acetic anhydride was added, and then the liquid temperature was raised to 60 ° C. and aging was performed for 5 hours. Subsequently, after the liquid temperature was lowered to 40 ° C. or less, 200.1 g of methanol was added to treat the remaining acetic anhydride. Subsequently, the reaction solution was added to 1770.4 g of methanol for reprecipitation. The obtained fibrous solid was filtered, rinsed with 300.9 g of methanol, and redissolved with 348.2 g of acetone. The solution was put into 1770.7 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 150.1 g of methanol, and dried under reduced pressure overnight to obtain 24.7 g (yield: 88.4%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.91, 3-position Ac group: 0.96, 6-position Ac group: 0.69, 2-position Bz group : 0.09, 3-position Bz group: 0.04, 6-position Bz group: 0.31. The degree of coloring was 100 in terms of Hazen unit colors.

Example 4 (Acylation of cellulose diacetate with propionic anhydride and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask: 0.79, 6-position Ac group: 0.64) 10.0 g (glucopyranose unit 0.039 mol) and pyridine 90.0 g (1.1 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 650.98 ppm. After adjusting the liquid temperature to 50 ° C. and adding 3.69 g (0.028 mol) of propionic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the reaction solution was put into 400.1 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.3 g of methanol, and then dried under reduced pressure in a vacuum dryer at 60 ° C. overnight. The dried fibrous solid was redissolved with 90.1 g (1.1 mol) of pyridine, and 4.98 g (0.035 mol) of benzoyl chloride was added dropwise thereto at room temperature over 30 minutes, and the liquid temperature was adjusted to 60 ° C. The mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or less, and 40.1 g of methanol was added to treat the remaining propionic anhydride. Subsequently, the reaction solution was added to 400.0 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.0 g of methanol, and then redissolved with 160.0 g of acetone. The solution was poured into 800.0 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 80.1 g of methanol, and then dried under reduced pressure overnight to obtain 11.9 g (yield: 93.8%) of cellulose acetate benzoate propionate. It was. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.78, 3-position Ac group: 0.74, 6-position Ac group: 0.68, 2-position Bz group : 0.14, 3-position Bz group: 0.17, 6-position Bz group: 0.17, 2-position Pr group: 0.08, 3-position Pr group: 0.09, 6-position Pr group: 0.15 there were. The degree of coloring was 200 in terms of Hazen unit colors.

Example 5 (Acylation of cellulose diacetate using acetic anhydride and propionic anhydride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask: 0.79, 6-position Ac group: 0.64) 10.0 g (glucopyranose unit 0.039 mol) and pyridine 90.0 g (1.1 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 600.30 ppm. After adjusting the liquid temperature to 50 ° C. and adding 8.04 g (0.079 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the reaction solution was put into 400.1 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.3 g of methanol, and then dried under reduced pressure in a vacuum dryer at 60 ° C. overnight. The dried fibrous solid was redissolved with 90.1 g (1.1 mol) of pyridine, and 4.61 g (0.035 mol) of propionic anhydride was added dropwise to the mixture at room temperature over 30 minutes. The temperature was maintained and the mixture was aged for 7 hours. After aging, the liquid temperature was lowered to 40 ° C. or less, and 40.2 g of methanol was added to treat the remaining propionic anhydride. Subsequently, the reaction solution was added to 400.2 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.3 g of methanol, and then redissolved with 160.0 g of acetone. The solution was poured into 801.1 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 80.0 g of methanol, and then dried under reduced pressure overnight to obtain 10.6 g (yield: 90.7%) of cellulose acetate propionate. . When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.82, the 3-position Ac group: 0.78, the 6-position Ac group: 0.76, and the 2-position Pr group : 0.18, 3-position Pr group: 0.22, and 6-position Pr group: 0.24. The coloring degree was 50 in terms of Hazen unit colors.

Comparative Example 1 (Acylation of cellulose diacetate with benzoyl chloride (total benzoate))
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask: 0.79, 6-position Ac group: 0.64) 50.0 g (glucopyranose unit 0.19 mol) and pyridine 450.3 g (5.7 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 581.5 ppm. The liquid temperature was adjusted to 30 ° C., and 35.9 g (0.26 mol) of benzoyl chloride was added, followed by aging at 30 ° C. for 12 hours. Subsequently, the reaction solution was poured into 2143.7 g of methanol to precipitate a fibrous solid. The obtained fibrous solid was collected by filtration, rinsed with 214.4 g of methanol, and redissolved with 800.1 g of acetone. The solution was poured into 4001.5 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 400.1 g of methanol, and dried under reduced pressure overnight to obtain 60.8 g (yield: 91.3%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.76, the 3-position Ac group: 0.79, the 6-position Ac group: 0.64, and the 2-position Bz group : 0.24, 3-position Bz group: 0.21, 6-position Bz group: 0.36. The coloring degree was 60 in terms of Hazen unit colors.

It is a figure which shows the ¹³ C-NMR spectrum (partial) of a cellulose acetate benzoate (3 types).

Claims (6)

  The cellulose acetate having a total substitution degree of acetyl group of 1.5 to 2.9 is reacted with a hydroxyl-reactive modifier, and a modifying group corresponding to the modifier is introduced into the 6-position hydroxyl group of the glucose skeleton, A method for producing a cellulose acetate derivative having a higher degree of substitution, wherein x is the number of moles of water contained in the reaction system at the start of the reaction, y is the number of moles of the hydroxyl group at the 6-position of the glucose skeleton of the raw material cellulose acetate, When the total number of moles of hydroxyl groups at the 2-position and 3-position of the glucose skeleton of the raw material cellulose acetate is z, the modifier is used in the range of more than x moles (x + y + 0.5z) moles or less. A method for producing a cellulose acetate derivative, which is selectively introduced into a hydroxyl group at the 6-position of a glucose skeleton.   The method for producing a cellulose acetate derivative according to claim 1, wherein the modifying agent is a compound selected from a carboxylic acid, a carboxylic acid halide, a carboxylic acid anhydride, and an isocyanate compound.   The cellulose acetate derivative according to claim 1, wherein after reacting the modifying agent, another modifying agent is reacted with the reaction product to introduce a modifying group corresponding to the modifying agent into at least a part of the remaining hydroxyl groups. Production method.   The total substitution degree of the acetyl group is 1.5 to 2.9, and the substitution degree of the acyl group other than the acetyl group at the 6-position is larger than the sum of the substitution degree of the acyl group other than the acetyl group at the 2-position and the 3-position. Characteristic cellulose acetate derivative.   The cellulose acetate derivative according to claim 4, wherein the acyl group substitution degree other than the acetyl group at the 6-position is 1.5 times or more the sum of the substitution degree of acyl groups other than the acetyl group at the 2-position and the 3-position.   The cellulose acetate derivative according to claim 4 or 5, wherein the acyl group other than the acetyl group is an aromatic acyl group or a propionyl group.

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