Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B3/00—Preparation of cellulose esters of organic acids
  • C08B3/16—Preparation of mixed organic cellulose esters, e.g. cellulose aceto-formate or cellulose aceto-propionate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B1/00—Preparatory treatment of cellulose for making derivatives thereof, e.g. pre-treatment, pre-soaking, activation
  • C08B1/02—Rendering cellulose suitable for esterification
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/08—Cellulose derivatives
  • C08L1/10—Esters of organic acids, i.e. acylates
  • C08L1/14—Mixed esters, e.g. cellulose acetate-butyrate

Definitions

• the present invention relates to a method for producing a cellulose derivative and a cellulose derivative.
• Bioplastics derived from plants as the raw material can contribute to countermeasures against the depletion of petroleum and the global warming, and therefore are beginning to be used for durable products such as an electronic device and an automobile, as well as general products such as a package, a container and a fiber.
• a representative example of the non-edible portion available as a raw material for bioplastics is cellulose, which is a main component of woods and vegetation, and various bioplastics utilizing it as the raw material have been developed and commercially produced.
• Such cellulose is a polymer in which ⁇ -glucose molecules are polymerized linearly. Due to the presence of three hydroxy groups in the ⁇ -glucose unit constituting cellulose, hydrogen bonds are formed intermolecularly (interchain) and intramolecularly. Accordingly, cellulose itself has no thermoplasticity and low solubility to a solvent except for special solvents. Further, cellulose has high water absorbability and low water resistance because it has many hydroxy groups, which are hydrophilic groups.
• a method for modifying cellulose As a method for modifying cellulose, a method is known in which the hydrogen atom in a hydroxy group in cellulose is replaced with a short-chain acyl group such as an acetyl group. According to this method, the number of the hydroxy groups can be reduced to thereby lower the formation rate of intermolecular hydrogen bonds. Further, it has been considered to introduce a long-chain organic group having a larger number of carbon atoms in addition to a short-chain acyl group such as an acetyl group to thereby produce a cellulose derivative having good thermoplasticity or water resistance.
• Patent Literature 1 describes a cellulose derivative in which at least some of the hydrogen atoms in the hydroxy groups in cellulose is replaced with a short-chain acyl group (e.g., an aliphatic acyl group having 2 to 4 carbon atoms) and a long-chain acyl group (e.g., an aliphatic acyl group having 5 to 20 carbon atoms), and discloses that the cellulose derivative has a low water absorption rate and good thermoplasticity, strength and rupture elongation, and is suitable for molding processing.
• a short-chain acyl group e.g., an aliphatic acyl group having 2 to 4 carbon atoms
• a long-chain acyl group e.g., an aliphatic acyl group having 5 to 20 carbon atoms
• Patent Literature 2 describes a cellulose derivative with cardanol introduced thereinto, and discloses that the cellulose derivative has improved thermoplasticity, mechanical properties and water resistance.
• Patent Literature 3 describes a cellulose derivative with cardanol and abietic acid introduced thereinto, and discloses that the cellulose derivative has improved thermoplasticity, mechanical properties and water resistance.
• Non Patent Literature 1 describes a cellulose derivative with a short-chain acyl group and a long-chain acyl group simultaneously introduced thereinto by using a special solvent (N-dimethylacetamide/lithium chloride system) for dissolving cellulose therein.
• a special solvent N-dimethylacetamide/lithium chloride system
• Non Patent Literature 2 describes a derivative with a short-chain acyl group and a long-chain acyl group simultaneously introduced thereinto by reacting a mixed acid anhydride constituted of a short-chain carboxylic acid and a long-chain carboxylic acid with cellulose in an acid catalyst system.
• Patent Literature 1
• Patent Literature 2
• Patent Literature 3
• a base catalyst is also available in place of an acid catalyst.
• a long-chain acylating agent is less reactive than that in the case of utilizing an acid catalyst, and hence it is difficult to obtain a cellulose derivative with a sufficient amount of long-chain acyl group introduced thereinto to develop desired properties.
• An object of the present invention is to provide a method which enables to efficiently produce a cellulose derivative with improved properties, and to provide a cellulose derivative with improved properties.
• a method for producing a cellulose derivative comprising reacting a mixed acid anhydride represented by the following chemical formula (A):
• R SH represents an organic group having 1 to 3 carbon atom(s); and R LO represents an organic group having an electron-withdrawing property, with cellulose in the presence of a base catalyst in an organic solvent having an electron pair-donating property to form a cellulose derivative with a first acyl group (—COR SH ) and a second acyl group)(—COR LO ) introduced at hydroxy groups in the cellulose.
• the first acyl group is an acyl group having 2 to 4 carbon atoms
• the second acyl group is an acyl group represented by the following chemical formula (B):
• —OR represents an organic group having 1 to 24 carbon atom(s) other than a cardanoxy group.
• a cellulose-based resin composition containing the above cellulose derivative as a base resin.
• a molded object obtained by molding the above cellulose-based resin composition.
• a method which enables to efficiently produce a cellulose derivative with improved properties can be provided, and a cellulose derivative with improved properties can be provided.
• a mixed acid anhydride constituted of a first carboxylic acid (e.g., a short-chain carboxylic acid) and a second carboxylic acid (e.g., a long-chain carboxylic acid), which are different to each other in acidity, is reacted with cellulose in the presence of a base catalyst in an organic solvent satisfying particular conditions, and thereby there can be obtained a cellulose derivative with a first acyl group (e.g., a short-chain acyl group) and a second acyl group (e.g., a long-chain acyl group) derived from the mixed acid anhydride, the acyl groups being introduced at hydroxy groups in the cellulose.
• a first carboxylic acid e.g., a short-chain carboxylic acid
• a second carboxylic acid e.g., a long-chain carboxylic acid
• a desired acyl group e.g., a long-chain acyl group
• a cellulose derivative with properties such as thermoplasticity, mechanical properties and water resistance
• Cellulose as the starting raw material is a linear polymer in which ⁇ -D-glucose molecules ( ⁇ -D-glucopyranose) are polymerized through ⁇ (1 ⁇ 4) glycoside linkages as shown in the following formula (1).
• Each of the glucose units constituting cellulose has three hydroxy groups (—OH).
• n is a natural number and represents the number of repeating units.
• hydroxy groups in cellulose molecules form intermolecular (interchain) hydrogen bonds, resulting that a sheet-like two-dimensional structure is formed in crystalline cellulose.
• the hydroxy groups at positions 6 and 3 are involved in the formation of the intermolecular (interchain) hydrogen bond.
• the hydroxy group at position 2 is involved in the formation of an intramolecular (intrachain) hydrogen bond to the hydroxy group at position 6.
• an intramolecular (intrachain) hydrogen bond is formed also between the oxygen atom forming the ether linkage (—O—) in the pyranose ring and the hydroxy group at position 3.
• a cellulose derivative with a first acyl group such as a short-chain acyl group and a second acyl group such as a long-chain acyl group introduced at these hydroxy groups in cellulose as the starting raw material is produced by utilizing acylation reaction.
• Cellulose is a main component of vegetation, particularly a cell wall of a plant cell and a plant fiber, and present therein bonding to other components such as lignin. Accordingly, cellulose can be obtained by a treatment for separating other components such as lignin from vegetation.
• wood pulp such as kraft pulp, which has a high content of cellulose
• cotton e.g., cotton linter
• pulp e.g., wood pulp
• the size and form of cellulose to be used as the starting raw material it is preferred to use a cellulose having an appropriate particle size and particle shape in view of reactivity at the acylation reaction, dispersibility in a reaction solvent and handleability at solid-liquid separation.
• a fibrous or powdery product having a diameter of 1 ⁇ m to 100 ⁇ m (preferably, 10 ⁇ m to 50 ⁇ m) or a length of 10 ⁇ m to 100 mm (preferably, 100 ⁇ m to 10 mm) can be used.
• the polymerization degree of cellulose to be used as the starting raw material is preferably in the range of 50 to 5000, more preferably in the range of 100 to 3000, and still more preferably 200 to 3000 in terms of a glucose polymerization degree (average polymerization degree).
• a cellulose-based resin using a cellulose derivative to be obtained may be insufficient in strength, heat resistance or the like.
• the melt viscosity of a cellulose-based resin using a cellulose derivative to be obtained may be too high to cause an obstacle in molding.
• Cellulose to be used as the starting raw material may have been mixed with chitin or chitosan, which has a similar structure to cellulose.
• the content of chitin and chitosan based on the whole mixture is preferably 30% by mass or less, preferably 20% by mass or less, and still more preferably 10% by mass or less.
• a first acyl group (—COR SH , e.g., a short-chain acyl group) and a second acyl group (—COR LO , e.g., a long-chain acyl group) are introduced at hydroxy groups in cellulose by utilizing acylation reaction.
• —COR SH e.g., a short-chain acyl group
• —COR LO e.g., a long-chain acyl group
• a mixed acid anhydride represented by the following formula (A) can be utilized as the main supply source for the second acyl group (—COR LO ).
• this mixed acid anhydride an acid anhydride constituted of a first carboxylic acid (a short-chain carboxylic acid) and a second carboxylic acid (e.g., a long-chain carboxylic acid) which are different to each other in acidity (acid dissociation constant: pKa) can be used.
• R SH represents an organic group having 1 to 3 carbon atom(s); and R LO represents an organic group having an electron-withdrawing property.
• an acid anhydride ((R LO CO) 2 O) of the second carboxylic acid (R LO COOH) can also be utilized as the supply source for the second acyl group) (—COR LO ).
• an acid anhydride ((R SH CO) 2 O) of the first carboxylic acid (R SH COOH: a short-chain carboxylic acid) can also be utilized in addition to the mixed acid anhydride represented by formula (A).
• the number of carbon atoms of the first acyl group is preferably in the range of 2 to 4, and is more preferably 2 or 3 (an acetyl group, a propionyl group), and still more preferably 2 (an acetyl group).
• the hydrocarbon group R SH (R SH in the formula) constituting the first acyl group is preferably a saturated chain hydrocarbon group having 1 to 3 carbon atom(s) (a methyl group, an ethyl group, a propyl group, an isopropyl group), more preferably a hydrocarbon group having 1 or 2 carbon atom(s) (a methyl group, an ethyl group), and still more preferably a hydrocarbon group having 1 carbon atom (a methyl group).
• the carboxylic acid corresponding to the first acyl group is preferably acetic acid, propionic acid, butyric acid or isobutyric acid, more preferably acetic acid or propionic acid, and still more preferably acetic acid.
• the number of the first acyl groups (—COR SH : a short-chain acyl group) per glucose unit (three hydroxy groups) (degree of substitution with the first acyl group: DS SH ) (average value), that is, the number of hydroxy groups replaced with the first acyl group per glucose unit (degree of substitution at hydroxy group) (average value) is preferably 0.1 or more, more preferably 0.5 or more, and still more preferably 1.0 or more in view of obtaining a sufficient effect of the introduction.
• DS SH is preferably 2.9 or less, and more preferably 2.5 or less.
• the degree of substitution with the first acyl group (DS SH ) corresponds to the ratio of the number of the first acyl groups bonded to cellulose relative to the cellulose in terms of glucose unit in the cellulose.
• the van der Waals' force (intermolecular bond) of the cellulose can be reduced.
• the formation of the intermolecular (interchain) hydrogen bond between the hydroxy groups at position 3 and 6 can be inhibited.
• the organic group R LO in the mixed acid anhydride represented by the above formula (A) has an electron-withdrawing property and the electron-withdrawing property is preferably higher than that of the hydrocarbon group R SH . This enables to enhance the reactivity of the second acyl group)(—COR LO to be introduced at a hydroxy group in cellulose to facilitate the introduction of the second acyl group, which is relatively more difficult to introduce than the first acyl group (a short-chain acyl group).
• acylation reaction is a nucleophilic substitution reaction
• the following reaction progresses and the second acyl group (—COR LO ) is preferentially introduced at the hydroxy group (—OH).
• R′—O—H represents cellulose.
• R LO is preferably a group containing at least one divalent group selected from the group consisting of an ether group (—O—), an ester group (—O—CO—), an amide group (—NH—CO—), a urethane group (—NH—CO—O—) and a carbonate group (—O—CO—O—); a first organic group bonding to the carbonyl carbon in the mixed acid anhydride of formula (A); and a second organic group linked to the first organic group through the divalent group.
• This divalent group is preferably bonding to a carbon atom (a carbon atom in the first organic group) bonding to the carbonyl carbon in the mixed acid anhydride of formula (A).
• the carbon atom (the carbon atom bonding to the carbonyl group) is preferably bonding the oxygen atom or nitrogen atom at the terminal of the divalent group (in the case that an oxygen atom is present at the terminal, the oxygen atom is preferably bonding to the above carbon).
• the total number of carbon atoms constituting the first organic group and the second organic group is preferably in the range of 2 to 48, and more preferably in the range of 2 to 25.
• the first organic group is preferably a saturated chain hydrocarbon group having 1 to 3 carbon atom(s), and more preferably a methylene group.
• the second organic group is preferably a hydrocarbon group having 1 to 24 carbon atom(s).
• the divalent group is preferably an ether group (—O—).
• R LO examples include a methoxymethyl group, an ethoxymethyl group, a phenoxymethyl group, a cardanoxymethyl group and a hydrogenated cardanoxymethyl group. That is, examples of the carboxylic acid corresponding to the second acyl group include methoxyacetic acid, ethoxyacetic acid, phenoxyacetic acid, cardanoxyacetic acid and hydrogenated cardanoxyacetic acids.
• Examples of the hydrogenated cardanoxymethyl group include 3-pentadecylphenoxymethyl group (—CH 2 —O—C 6 H 4 —(CH 2 ) 14 CH 3 ), in which the double bonds in the aromatic ring have not been hydrogenated, and 3-pentadecylcyclohexyloxymethyl group (—CH 2 —O—C 6 H 10 —(CH 2 ) 14 CH 3 ), in which the double bonds in the long chain portion and the aromatic ring have been hydrogenated.
• examples of R LO include an aryl group such as a phenyl group and a tolyl group; and an aralkyl group such as a benzyl group and a phenylethyl group.
• examples of the carboxylic acid corresponding to the second acyl group include benzoic acid; methyl-substituted benzoic acids such as o-methylbenzoic acid, m-methylbenzoic acid and p-methylbenzoic acid; and aromatic carboxylic acids such as phenylacetic acid, p-methylphenylacetic acid, 3-phenylpropionic acid, p-methylphenylpropionic acid and cinnamic acid.
• the cellulose, the first carboxylic acid (R SH COOH: a short-chain carboxylic acid) corresponding to the first acyl group (—COR SH : a short-chain acyl group) and the second carboxylic acid (R LO COOH) corresponding to the second acyl group (—COR LO ) which constitute a cellulose derivative produced by the method for production according to an exemplary embodiment of the present invention are preferably each derived from a natural source such as a plant or each prepared by using an organic compound derived from a natural source such as a plant as the raw material.
• a monocarboxylic acid prepared by using cardanol or a cardanol derivative extracted from a cashew nut shell as the raw material can be suitably utilized as the second carboxylic acid (R LO COOH) corresponding to the second acyl group (—COR LO ).
• a hydrogenated cardanoxyacetic acid (3-pentadecylphenoxyacetic acid) prepared by using a hydrogenated cardanol (m-n-pentadecylphenol (or 3-pentadecylphenol): HO—C 6 H 4 —(CH 2 ) 14 CH 3 ), in which the double bonds in the long chain portion have been hydrogenated and the benzene ring has not been hydrogenated, as the raw material can be suitably utilized as the second carboxylic acid (R LO COOH) corresponding to the second acyl group (—COR LO ).
• a hydrogenated cardanoxyacetic acid (3-pentadecylcyclohexyloxyacetic acid) prepared by using a hydrogenated cardanol (3-pentadecylcyclohexanol: HO—C 6 H 10 —(CH 2 ) 14 CH 3 ), in which the double bonds in the long chain portion and the benzene ring have been hydrogenated, as the raw material can be suitably utilized as the second carboxylic acid (R LO COOH).
• a cellulose derivative produced by the method for production according to an exemplary embodiment of the present invention can contain as the second acyl group an acyl group corresponding to a monocarboxylic acid other than monocarboxylic acids prepared by using cardanol or a cardanol derivative (a cardanol derivative having a benzene ring derived from cardanol) as the raw material. That is, in this cellulose derivative, the first acyl group and the second acyl group are introduced at at least some of hydroxy groups contained in cellulose, and the first acyl group and the second acyl group are an aliphatic acyl group having 2 to 4 carbon atoms and an acyl group represented by the following formula (B), respectively:
• —OR represents an organic group having 1 to 24 carbon atom(s) other than a cardanoxy group.
• This cellulose derivative can be efficiently produced by the method for production according to an exemplary embodiment of the present invention, and can have improved properties (e.g., thermoplasticity and shock resistance) depending on the structure and the amount of the first and second acyl groups to be introduced.
• the second acyl group is preferably an organic group having no aromatic ring from the viewpoint of the coloring or hue of a resin to be obtained. Accordingly, from the viewpoint of the coloring or hue of a resin to be obtained, R in the formula is preferably an aliphatic hydrocarbon group having 1 to 24 carbon atom(s), and more preferably an aliphatic saturated hydrocarbon.
• the first acyl group (an aliphatic acyl group having 2 to 4 carbon atoms) is, as with the above-described first acyl group (—COR SH ), preferably an acetyl group or a propionyl group, and particularly preferably an acetyl group.
• cardanoxy group means a group containing a benzene ring derived from cardanol, and hence cardanoxy groups represented by the following formulae:
• —OR in the above formula (B) can contain a 3-pentadecylcyclohexyloxy group (—O—C 6 H 10 —(CH 2 ) 14 CH 3 ), which is a cardanoxy group in which the double bonds in both of the long chain portion and the benzene ring derived from cardanol have been hydrogenated.
• the number of the second acyl groups (—COR LO , e.g., a long-chain acyl group) per glucose unit (three hydroxy groups) in cellulose (degree of substitution with the second acyl group: DS LO ) (average value), that is, the number of hydroxy groups replaced with the second acyl group per glucose unit (degree of substitution at hydroxy group) (average value) is preferably 0.1 or more, more preferably 0.2 or more, and still more preferably 0.4 or more in view of obtaining a sufficient effect of the introduction.
• DS LO is preferably 2.9 or less, and more preferably 1.5 or less.
• the degree of substitution with the second acyl group (DS LO ) corresponds to the ratio of the number of the second acyl groups bonded to cellulose relative to the cellulose in terms of glucose unit in the cellulose.
• the total of DS SH and DS LO is preferably in the range of (DS SH +DS LO ) ⁇ 2 in order to effectively inhibit the formation of an intermolecular (interchain) hydrogen bond by hydroxy groups (—OH) in the cellulose derivative.
• the total of the degrees of substitution (DS SH +DS LO ) is more preferably in the range of (DS SH +DS LO ) ⁇ 2.3, still more preferably in the range of (DS SH +DS LO ) ⁇ 2.4, and particularly preferably in the range of (DS SH +DS LO ) ⁇ 2.5 from the viewpoint of inhibiting the formation of an intramolecular (intrachain) hydrogen bond by hydroxy groups (—OH) in the molecule.
• the characteristics (physical properties) of a cellulose derivative to be made also depend on the ratio of DS SH to DS LO (DS LO /DS SH ) in addition to the total degree of substitution (DS SH +DS LO ). In other words, it is necessary to appropriately select the total degree of substitution (DS SH +DS LO ) and the ratio of degrees of substitution (DS LO /DS SH ) depending on characteristics (physical properties) required for a cellulose derivative to be made.
• the total degree of substitution (DS SH +DS LO ) and the ratio of the degrees of substitution (DS LO /DS SH ) under conditions that the number of substitution with the second acyl group (such as a long-chain acyl group) per glucose unit in a cellulose derivative to be made (DS LO ) (average value) is in the range of 0.1 to 2.9, and preferably in the range of 0.1 to 1.5.
• a long-chain hydrocarbon group possessed by the monovalent group R LO constituting the long-chain acyl group can be utilized to modify physical properties such as fluidity and thermoplasticity.
• the long-chain hydrocarbon group possessed by the monovalent group R LO preferably has the number of carbon atoms more than that of the monovalent group R SH in a short-chain acyl group (—COR SH ), which is the first acyl group, by two or more, more preferably by three or more, and still more preferably five or more.
• one type of the second acyl group (—COR LO : e.g., a long-chain acyl group) is usually introduced; however, two or more types thereof may optionally be introduced.
• the ratio of the amounts of the respective second acyl groups to be introduced is determined depending on the reactivities of the mixed acid anhydrides (R SH —CO—O—CO—R LO ) as supply sources for the respective second acyl groups and the concentrations of the respective mixed acid anhydrides contained in the reaction solution.
• the amounts of the respective second acyl groups)(—COR LO to be introduced and the amount of the first acyl group (a short-chain acyl group: —COR SH ) to be introduced can be regulated to achieve a desired ratio by selecting the concentrations of the respective mixed acid anhydride (R SH —C—O—C—R LO ) contained in the reaction solution and the concentration of the acid anhydride ((R SH CO) 2 O) derived from a short-chain carboxylic acid (R SH COOH).
• the mixed acid anhydride (R SH —CO—O—CO—R LO ) to be utilized for the acylation reaction can be prepared through the following reaction by using, for example, the second carboxylic acid (R LO COOH: e.g., a long-chain carboxylic acid) or an alkali metal salt of the second carboxylic acid (such as R LO COONa: e.g., a long-chain carboxylic acid sodium salt) and an acid chloride (R SH CO—Cl) derived from the first carboxylic acid (R SH COOH: a short-chain carboxylic acid).
• R LO COOH e.g., a long-chain carboxylic acid
• R LO COONa e.g., a long-chain carboxylic acid sodium salt
• R SH CO—Cl acid chloride
• the mixed acid anhydride (R SH —CO—O—CO—R LO ) to be utilized for the acylation reaction can be prepared through the following reaction by using the second carboxylic acid (R LO COOH) and an acid anhydride ((R SH CO) 2 O) derived from the first carboxylic acid (R SH COOH).
• the second carboxylic acid (R LO COOH) and the mixed acid anhydride generated (R SH —CO—O—CO—R LO ) reacts to form an acid anhydride ((R LO CO) 2 O) of the second carboxylic acid (R LO COOH) through the following reaction.
• the reaction mixture to be obtained contains the mixed acid anhydride (R SH —CO—O—CO—R LO ), the acid anhydride ((R LO CO) 2 O) of the second carboxylic acid, the first carboxylic acid (R SH COOH), which is a by-product of the reaction, and the second carboxylic acid (R LO COOH) and the acid anhydride ((R SH CO) 2 O) of the first carboxylic acid, which are residual raw materials.
• each of the concentrations of the mixed acid anhydride (R SH —CO—O—CO—R LO ), the anhydride ((R LO CO) 2 O) of the second carboxylic acid, the first carboxylic acid (R SH COOH), the second carboxylic acid (R LO COOH) and the acid anhydride ((R SH CO) 2 O) of the first carboxylic acid in the reaction mixture to be obtained is determined depending on the concentration of the second carboxylic acid (R LO COOH) as the starting raw material at the beginning of the reaction and the concentration of the acid anhydride ((R SH CO) 2 O) of the first carboxylic acid as the starting raw material at the beginning of the reaction.
• the above reaction mixture can be utilized as a supply source for the second acyl group (—COR LO ) and a supply source for the first acyl group (—COR SH ) in the acylation reaction.
• the ratio of the amount of the first acyl group (—COR SH ) to be introduced to the amount of the second acyl group (—COR LO ) to be introduced can be controlled by adjusting the ratio of the total of the concentration of the mixed acid anhydride (R SH —CO—O—CO—R LO ) and the concentration of the acid anhydride ((R LO CO) 2 O) of the second carboxylic acid to the concentration of the acid anhydride ((R SH CO) 2 O) of the first carboxylic acid.
• a separately-prepared mixture in which the mixed acid anhydride (R SH —CO—O—CO—R LO ), the acid anhydride ((R LO CO) 2 O) of the second carboxylic acid and the acid anhydride ((R SH CO) 2 O) of the first carboxylic acid are mixed together in a predetermined concentration ratio can be utilized as a supply source for the second acyl group (—COR LO ) and the first acyl group (—COR SH ).
• the properties of a cellulose derivative to be made can be modified; for example, water resistance or thermoplasticity can be improved by controlling the ratio of the amounts of the second acyl group)(—COR LO and the first acyl group (—COR SH ) to be introduced into cellulose in the acylation reaction and controlling the total of the amounts of the second acyl group (—COR LO ) and the first acyl group (—COR SH ) to be introduced into cellulose in the acylation reaction.
• the acylation reaction is preferably performed in a solvent having a high electron pair-donating property.
• This enables to efficiently introduce the first acyl group (—COR SH : a short-chain acyl group) and the second acyl group (—COR LO : e.g., a long-chain acyl group) at hydroxy groups in cellulose.
• a solvent having a high electron pair-donating property has a high hydrogen bond-receptive ability, and therefore can activate hydrogen bonds abundantly present in cellulose to some extent, which promotes the reaction.
• the solvent to be used for the method for production is preferably an aprotic organic solvent which exhibits no reactivity against the acid anhydride to be used in the acylation reaction and can dissolve the acid anhydride to be used in the acylation reaction therein.
• an acetic acid molecule is adsorbed on a hydroxy group in the cellulose via a hydrogen bond.
• This acetic acid molecule forms a hydrogen bond with the solvent having a high electron donating property, for example, pyridine to form an acetic acid-pyridine complex, and as the result, the acetic acid molecule is eliminated from the hydroxy group in the cellulose.
• the hydroxy group from which the acetic acid molecule has been eliminated is susceptible to the acylation reaction compared to a hydroxy group on which an acetic acid molecule is adsorbed.
• the mixed acid anhydride (R SH —CO—O—CO—R LO ) and the acid anhydride (R SH CO) 2 O) of a short-chain carboxylic acid are consumed to form the short-chain carboxylic acid (R SH —COOH) as the by-product.
• an organic solvent having a high electron pair-donating property for example, pyridine
• this short-chain carboxylic acid (R SH —COOH) as the by-product can be converted to a short-chain carboxylic acid (R SH —COOH)-pyridine complex to thereby avoid the elevation of the concentration of the short-chain carboxylic acid (R SH —COOH) in the reaction liquid.
• the second carboxylic acid (R LO COOH) and the short-chain carboxylic acid (R SH —COOH) contained in the mixture can be converted in advance to a short-chain carboxylic acid (R SH —COOH)-pyridine complex and a second carboxylic acid (R LO COOH)-pyridine complex, respectively.
• an organic solvent having a high electron pair-donating property for example, pyridine
• an organic solvent having a donor number (Dn), which is a measure of an electron pair-donating property, of 10 or more is preferably used, more preferably an organic solvent having a donor number of 13 or more is used, and particularly preferably an organic solvent having a donor number of 21 or more is used.
• the acylation reaction (esterification reaction) can be promoted by performing the reaction in the presence of a base catalyst, which enables to efficiently introduce the first acyl group (—COR SH : a short-chain acyl group) and the second acyl group (—COR LO : e.g., a long-chain acyl group) at hydroxy groups in cellulose.
• a base catalyst acts on the hydrogen atom in a hydroxy group to induce polarization to this hydroxy group, and hence the acylation reaction is promoted.
• DMAP N,N-dimethyl-4-aminopyridine
• a nitrogen-containing basic organic compound having a tertiary amine structure is preferably used, that is, a basic organic compound containing a nitrogen atom constituting a tertiary amine structure is preferably used.
• a base catalyst include amine-based compounds (such as trimethylamine, triethylamine, N,N-diisopropylethylamine, quinuclidine, 1,4-ethylenepiperazine (DABCO), tetramethylethylenediamine), pyridine-based compounds (such as dimethylaminopyridine (DMAP: N,N-dimethyl-4-aminopyridine) and 4-pyrrolidinopyridine), imidazole-based compounds (such as 1-methylimidazole and 1,2-dimethylimidazole), amidine-based compounds (such as diazabicycloundecene (DBU) and diazabicyclocyclononene (DBN)).
• DMAP dimethylaminopyridine
• DBN dimethyl
• the conversion rate of the hydroxy groups can be appropriately set.
• the number of residual hydroxy groups per glucose unit in a cellulose derivative to be produced (level of residual hydroxy group: DS OH ) (average value) can be set to 0 to 2.8.
• DS OH is preferably 0.7 or less, and more preferably 0.5 or less. Some of the hydroxy groups may be remaining, and for example, DS OH can be set to 0.01 or more, and even 0.1 or more.
• the level of residual hydroxy group (DS OH ) corresponds to the ratio of the number of residual hydroxy groups relative to the cellulose derivative in terms of glucose unit in the cellulose derivative.
• a short-fiber cellulose can be used which are commonly obtained by refining cotton (e.g., cotton linter) or pulp (e.g., wood pulp).
• This short-fiber cellulose is usually adsorbing moisture, and it is preferred to perform a pre-treatment step to remove the moisture being adsorbed prior to a reaction step to introduce the first acyl group (—OCR SH : a short-chain acyl group) and the second acyl group (—OCR LO : e.g., a long-chain acyl group) through the acylation reaction.
• —OCR SH a short-chain acyl group
• —OCR LO e.g., a long-chain acyl group
• hydrolysis reaction of an acid anhydride such as the mixed acid anhydride (R SH —CO—O—CO—R LO ), the acid anhydride ((R SH CO) 2 O) derived from the first carboxylic acid (R SH COOH)) to be used in the acylation reaction is inhibited, and therefore the reduction of reactivity due to consumption of the acid anhydride caused by the water being adsorbed is avoided.
• an acid anhydride such as the mixed acid anhydride (R SH —CO—O—CO—R LO )
• an activation step to contact an “activation solvent” with cellulose as the raw material, the dissociation of intramolecular (intrachain) and intermolecular (interchain) hydrogen bonds in the cellulose caused by hydroxy groups in the cellulose can be promoted. This enables to enhance the reactivity of the cellulose.
• the dissociation of the hydrogen bond between the oxygen atom of the hydroxy group at position 6 and the hydrogen atom of the hydroxy group at position 2 or the dissociation of the hydrogen bond between the oxygen atom of the hydroxy group at position 3 and the hydrogen atom of the hydroxy group at position 6 in an adjacent cellulose molecule is promoted through the following mechanism.
• the water (H 2 O) being adsorbed on a hydroxy group is removed through the following mechanism.
• the hydrogen-bonded complex structure constituted of the hydroxy group and the water being adsorbed thereon dissociates, and the detached water molecule becomes in a state of being solvated by an activation solvent molecule.
• the hydroxy group from which the water molecule has been dissociated and an activation solvent molecule form a complex structure, and thereby the readsorption of a water molecule on a hydroxy group is prevented.
• the activation treatment step for the purpose of removing water (H 2 O) in cellulose and swelling an aggregate (powder) by utilizing the activation solvent can be performed by using a wet process by employing a method in which a powder cellulose is soaked in the activation solvent (soaking method), a method in which the activation solvent is sprayed on a powder cellulose or the like to contact the cellulose with the activation solvent.
• Performing the activation treatment step as described above allows various compounds such as the solvent, the base catalyst and the acid anhydride contained in the reaction solution, which are utilized in performing the subsequent acylation reaction, to easily enter into a space between cellulose molecule chains within the swelled aggregate (powder). As the result, the efficiency of the acylation reaction of cellulose is enhanced.
• activation treatment step can be applied treatment conditions of common activation treatments applied for cellulose as the raw material, in performing acetylation of cellulose by utilizing acetic anhydride ((CH 3 CO) 2 O).
• a hydrophilic organic solvent which has a high affinity for a hydroxy group present in the glucose unit constituting cellulose and is excellent in an ability to dissolve water therein, is preferably used.
• water and a hydrophilic organic solvent can also be used as the activation solvent to perform the activation treatment.
• hydrophilic organic solvent examples include water-miscible monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enantoic acid, caprylic acid and pelargonic acid; water-miscible alcohols such as methanol, ethanol, 1-propanol and 2-propanol; water-miscible nitrogen-containing organic compounds such as dimethylformamide, formamide and ethanolamine; and water-miscible sulfoxide compounds such as dimethylsulfoxide. Two or more of these can also be used in combination.
• water-miscible monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enantoic acid, caprylic acid and pelargonic acid
• water-miscible alcohols such as methanol, ethanol, 1-propanol and 2-propanol
• water-miscible nitrogen-containing organic compounds such
• An activation treatment with water and acetic acid, an activation treatment with acetic acid or an activation treatment with dimethylsulfoxide is preferably used, and an activation treatment with water and acetic acid is more preferably used.
• a powder cellulose is dispersed in water to swell with moisture, followed by separating excessive moisture, and thereafter the resultant can be dispersed in acetic acid so as to replace water molecules (H 2 O) in the cellulose with acetic acid molecules (CH 3 COOH) and dissociate a part of the hydrogen-bonded complex structures in the cellulose.
• cellulose can be dissolved in dimethylsulfoxide without being swelled with moisture, so as to replace water molecules (H 2 O) contained in the cellulose with dimethylsulfoxide molecules ((CH 3 ) 2 SO) and dissociate a part of the hydrogen-bonded complex structures in the cellulose.
• the activation treatment with dimethylsulfoxide as the activation solvent tends to improve the amount of long-chain acyl group to be introduced.
• the activation treatment with acetic acid as the activation solvent is advantageous from the viewpoint of purification of a product of interest and recovery of raw materials because the number of components in the reaction system is not increased.
• the amount of the activation solvent to be used can be set, for example, to 10 parts by mass or more, preferably 20 parts by mass or more, and more preferably 30 parts by mass or more based on 100 parts by mass of cellulose.
• the amount of the activation solvent to be used in soaking cellulose in the activation solvent can be set to, for example, 1 or more, preferably 5 or more, and more preferably 10 or more in a mass ratio to cellulose (amount of activation solvent/amount of cellulose).
• the amount of the activation solvent to be used is preferably 300 or less, more preferably 100 or less, and still more preferably 50 or less in a mass ratio to cellulose (amount of activation solvent/amount of cellulose).
• the temperature in the activation treatment can be appropriately set, for example, in the range of 0 to 100° C. From the viewpoint of the efficiency of the activation and reduction of energy costs required for temperature maintenance, the temperature is preferably set in the range of 10 to 40° C., and more preferably in the range of 15 to 35° C.
• the duration for the activation treatment can be appropriately set, for example, in the range of 0.1 to 72 hours. From the viewpoint of obtaining a sufficient effect of the activation and shortening treatment time, the duration is preferably set in the range of 0.1 to 24 hours, and more preferably in the range of 0.5 to 3 hours.
• an excess of the activation solvent can be removed by using a solid-liquid separation method such as suction filtration.
• the replacement treatment of the activation solvent with the reaction solvent can be achieved by soaking the cellulose after the activation treatment with the solvent to be used in the subsequent acylation reaction according to the above soaking method of the activation treatment.
• the cellulose after the activation treatment is soaked in the reaction solvent to be used in the acylation reaction, due to the reaction solvent entering into the cellulose, the activation solvent remaining in the cellulose is detached and extracted into the reaction solvent.
• the cellulose is swelled with the reaction solvent to be in a state that no activation solvent is contained.
• the reaction solvent which has extracted the activation solvent can be removed by using a solid-liquid separation method such as suction filtration.
• an acylation reaction is performed by using a reaction solution containing the above-described mixed acid anhydride, the solvent and the base catalyst to introduce the first acyl group (—OCR SH : a short-chain acyl group) and the second acyl group (—OCR LO : e.g., a long-chain acyl group).
• a reaction solution containing the above-described mixed acid anhydride, the solvent and the base catalyst to introduce the first acyl group (—OCR SH : a short-chain acyl group) and the second acyl group (—OCR LO : e.g., a long-chain acyl group).
• heating or stirring can be performed as necessary.
• a solvent is preferably used which can dissolve an acid anhydride (acylating agent) such as the mixed acid anhydride and the base catalyst homogeneously, allow the reaction solution to enter into the cellulose and elute the by-product (the first carboxylic acid: a short-chain carboxylic acid) after the acylation reaction and the base catalyst from the cellulose.
• an acid anhydride acylating agent
• the reaction solution can enter into the cellulose and elute the by-product (the first carboxylic acid: a short-chain carboxylic acid) after the acylation reaction and the base catalyst from the cellulose.
• the amount of the solvent to be used for the reaction solution is, for example, preferably 1 or more, preferably 5 or more, and more preferably 10 or more in a mass ratio to cellulose (amount of solvent/amount of cellulose) from the viewpoint of progressing the reaction sufficiently, and preferably 300 or less, more preferably 100 or less, and 50 times or less from the viewpoint of efforts for removing the reaction solvent after an acylation reaction, reduction of material costs and the like.
• the amount of the base catalyst contained in the reaction solution is preferably in the range of 0.1% by mass or more and 100% by mass or less, more preferably in the range of 1% by mass or more and 80% by mass or less, and still more preferably in the range of 3% by mass or more and 50% by mass or less based on the amount of cellulose from the viewpoint of obtaining a sufficient effect of promoting the acylation reaction.
• the temperature of the reaction solution in the acylation reaction is preferably 10° C. or higher, more preferably 20° C. or higher, and still more preferably 30° C. or higher from the viewpoint of reaction efficiency and the like, and preferably 200° C. or lower, more preferably 150° C. or lower, and still more preferably 100° C. or lower from the viewpoint of suppression of a decomposition reaction, reduction of energy costs and the like.
• the reaction duration can be appropriately selected considering the reaction temperature, the reaction duration is preferably 0.5 hours or longer, and more preferably 1 hour or longer from the viewpoint of progressing the reaction sufficiently, and preferably 24 hours or shorter, and more preferably 15 hours or shorter from the viewpoint of making the production process more efficient.
• the cellulose derivative After the acylation reaction of cellulose, in the case that a part of a cellulose derivative produced constitutes a solid phase while the other part is in a state of being dissolved in the reaction solution, the cellulose derivative can be recovered in the following manner.
• a poor solvent is added to the reaction solution to precipitate the cellulose derivative dissolved in the reaction solution (reprecipitation), and the resultant is then subjected to a common solid-liquid separation to separate/remove the reaction solvent to which the poor solvent has been added.
• low-boiling point components such as the solvent and the by-product (such as acetic acid) in the reaction solution are removed under a reduced pressure, and to the obtained crude product containing the cellulose derivative is added a poor solvent to wash the crude product.
• This allows to recover both the cellulose derivative constituting a solid phase and the cellulose derivative dissolved in the reaction solution simultaneously.
• the latter method in which a crude product is washed with a poor solvent, can reduce the amount of the poor solvent to be used for recovery.
• a part of the cellulose derivative produced constituting a solid phase can be recovered by performing a common solid-liquid separation method to separate/remove the reaction solution. Further, the cellulose derivative dissolved in the reaction solution separated can be recovered by adding a poor solvent to this reaction solution to precipitate (reprecipitation) and the resultant is then subjected to a common solid-liquid separation to separate/remove the reaction solution to which the poor solvent has been added.
• the cellulose derivative constituting a solid phase after the acylation of cellulose and the cellulose derivative reprecipitated from the reaction solution can be recovered to use in a mixture thereafter.
• the first acyl group (—COR SH : a short-chain acyl group) and the second acyl group (—COR LO : e.g., a long-chain acyl group) have been introduced by utilizing hydroxy groups in cellulose. Accordingly, the cellulose derivative is reduced in intermolecular (interchain) hydrogen bonds (cross-linking sites) compared to cellulose.
• this long-chain acyl group acts as an internal plasticizer, which allows the cellulose derivative to exhibit good thermoplasticity.
• introduction of a highly-hydrophobic acyl group as the second acyl group can further improve water resistance.
• the number of residual hydroxy groups can be made larger than that of a common cellulose derivative, and thus the cellulose derivative can be obtained in a state that a part of the cellulose crystal remains with some of the intramolecular and intermolecular hydrogen bonds saved.
• the hydrogen-bonded portion has a reinforcing function, the strength and the stiffness are improved compared to those of a common cellulose derivative in which no cellulose crystal remains.
• a cellulose derivative obtained by using the method for production according to an exemplary embodiment of the present invention can be added an additive depending on desired properties to obtain a cellulose-based resin composition suitable for a molding material.
• cellulose-based resin composition can be applied various additives used for a common thermoplastic resin.
• addition of a plasticizer can further improve the thermoplasticity of the cellulose-based resin composition and the elongation at rupture of the molded object.
• plasticizer examples include phthalates such as dibutyl phthalate, diaryl phthalates, diethyl phthalate, dimethyl phthalate, di-2-methoxyethyl phthalate, ethyl phthalyl-ethyl glycolate and methyl phthalyl-ethyl glycolate; tartrates such as dibutyl tartrate; adipates such as dioctyl adipate and diisononyl adipate; polyalcohol esters such as triacetin, diacetyl glycerin, tripropionitrile glycerin and glycerin monostearate; phosphates such as triethyl phosphate, triphenyl phosphate and tricresyl phosphate; aliphatic dicarboxylic acid dialkyl ester such as dibutyl adipate, dioctyl adipate, dibutyl azelate, dioctylic acid dial
• plasticizers examples include cyclohexanedicarboxylates such as dihexyl cyclohexanedicarboxylate, dioctyl cyclohexanedicarboxylate and di-2-methyloctyl cyclohexanedicarboxylate; trimellitates such as dihexyl trimellitate, diethylhexyl trimellitate and dioctyl trimellitate; pyromellitates such as dihexyl pyromellitate, diethylhexyl pyromellitate and dioctyl pyromellitate.
• cyclohexanedicarboxylates such as dihexyl cyclohexanedicarboxylate, dioctyl cyclohexanedicarboxylate and di-2-methyloctyl cyclohexanedicarboxylate
• trimellitates such as dihexyl trimellitate, die
• cellulose-based resin composition according to an exemplary embodiment of the present invention can be added as necessary an inorganic or organic granular or fibrous filler. Addition of the filler can further improve the strength and the stiffness.
• Examples of such a filler include mineral particles (such as talk, mica, calcined diatomaceous earth, kaolin, sericite, bentonite, smectite, clay, silica, a quartz powder, a glass bead, a glass powder, a glass flake, a milled fiber, wallastonite (or wollastonite)); boron-containing compounds (such as boron nitride, boron carbide and titanium boride); metal carbonates (such as magnesium carbonate, ground calcium carbonate and precipitated calcium carbonate); metal silicates (such as calcium silicate, aluminum silicate, magnesium silicate and magnesium aluminosilicate); metal oxides (such as magnesium oxide); metal hydroxides (such as aluminum hydroxide, calcium hydroxide and magnesium hydroxide); metal sulfates (such as calcium sulfate and barium sulfate); metal carbides (such as silicon carbide, aluminum carbide and titanium carbide); metal nitri
• the fibrous filler examples include organic fibers (such as natural fibers and papers); inorganic fibers (such as a glass fiber, an asbestos fiber, a carbon fiber, a silica fiber, a silica-alumina fiber, wollastonite, a zirconia fiber and a potassium titanate fiber); and metal fibers.
• organic fibers such as natural fibers and papers
• inorganic fibers such as a glass fiber, an asbestos fiber, a carbon fiber, a silica fiber, a silica-alumina fiber, wollastonite, a zirconia fiber and a potassium titanate fiber
• metal fibers such as a glass fiber, an asbestos fiber, a carbon fiber, a silica fiber, a silica-alumina fiber, wollastonite, a zirconia fiber and a potassium titanate fiber.
• fillers can be used singly or two or more thereof can be used in combination.
• a flame retardant To the cellulose-based resin composition according to an exemplary embodiment of the present invention can be added as necessary a flame retardant. Addition of the flame retardant can impart flame retardance.
• the flame retardant examples include metal hydrates such as magnesium hydroxide, aluminum hydroxide and hydrotalcite; basic magnesium carbonate, calcium carbonate, silica, alumina, talc, clay, zeolite, bromide-based flame retardants, antimony trioxide, phosphate-based flame retardants (such as aromatic phosphates and aromatic condensed phosphates) and compounds containing phosphorous and nitrogen (phosphazene compounds). These flame retardants can be used single or two or more thereof can be used in combination.
• a shock resistance improver To the cellulose-based resin composition according to an exemplary embodiment of the present invention can be added as necessary a shock resistance improver. Addition of the shock resistance improver can enhance the shock resistance of the molded object.
• shock resistance improver examples include rubber components and silicone compounds.
• the rubber component include a natural rubber, an epoxidized natural rubber and a synthetic rubber.
• the silicone compound include organic polysiloxanes formed through polymerization of an alkyl siloxane, an alkylphenyl siloxane or the like; or modified silicone compounds in which a side chain or a terminal of the organic polysiloxane is modified with a polyether, methylstyryl, an alkyl, a higher fatty acid ester group, an alkoxy group, fluorine, an amino group, an epoxy group, a carboxyl group, a carbinol group, a methacryl group, a mercapto group, a phenol group or the like.
• These shock resistance improvers can be used singly or two or more thereof can be used in combination.
• a modified silicone compound (a modified polysiloxane compound) is preferably used.
• a modified silicone compound a modified polydimethylsiloxane is preferably used which has a main chain composed of repeating units of dimethylsiloxane and has a structure in which some of methyl groups in the side chain or the terminal is replaced with an organic group including at least one group selected from an amino group, an epoxy group, a carbinol group, a phenol group, a mercapto group, a carboxyl group, a methacryl group, a long-chain alkyl group, an aralkyl group, a phenyl group, a phenoxy group, an alkylphenoxy group, a long-chain fatty acid ester group, a long-chain fatty acid amide group and a polyether group.
• Such an organic substituent possessed by the modified silicone compound improves the affinity for the above-described cellulose derivative to enhance the dispersibility in the cellulose-based resin composition, and hence a molded object excellent in shock resistance can be obtained by using the cellulose-based resin composition.
• Examples of the above organic substituent contained in the modified silicone compound include those represented by the following formulae (3) to (21).
• a and b each represent an integer of 1 to 50.
• R 1 to R 10 , R 12 to R 15 , R 19 and R 21 each represent a divalent organic group.
• the divalent organic group include alkylene groups such as a methylene group, an ethylene group, a propylene group and a butylene group; alkylarylene groups such as a phenylene group and a tolylene group; oxyalkylene groups and polyoxyalkylene groups such as —(CH 2 —CH 2 —O)c- (c represents an integer of 1 to 50) and —[CH 2 —CH(CH 3 )—O] d — (d represents an integer of 1 to 50); and —(CH 2 ) e —NHCO— (e represents an integer of 1 to 8).
• an alkylene group is preferred, and an ethylene group and propylene group are particularly preferred.
• R 11 , R 16 to R 18 , R 20 and R 22 each represent an alkyl group having 20 or less carbon atoms.
• the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group and a pentadecyl group.
• the above alkyl group may have one or more unsaturated bond(s) in the structure.
• the modified silicone compound can be dispersed in the cellulose derivative in the matrix in an appropriate particle diameter (e.g., 0.1 ⁇ m or larger and 100 ⁇ m or smaller).
• an appropriate particle diameter e.g., 0.1 ⁇ m or larger and 100 ⁇ m or smaller.
• Such a total average content of organic substituents is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and preferably 70% by mass or less, and more preferably 50% by mass or less.
• an appropriate amount of organic substituent are contained in the modified silicone compound, the affinity for the cellulose-based resin is improved to allow the modified silicone compound to be dispersed in the cellulose-based resin composition in an appropriate particle diameter and further enable to suppress bleed-out due to the separation of the modified silicone compound in a molded article.
• the total average content of organic substituents is too low, it is difficult to disperse the modified silicone compound in the cellulose-based resin composition in an appropriate particle diameter.
• the average content of the organic substituent in this modified polydimethylsiloxane compound can be determined by using the following formula (I).
• the equivalent of an organic substituent is the average value of the mass of the modified silicone compound per 1 mole of the organic substituent.
• the average content of the organic substituent in this modified polydimethylsiloxane compound can be determined by using the following formula (II).
• x is the average value of the mole fraction of the organic substituent-containing siloxane repeating unit to all the siloxane repeating units in the modified polydimethylsiloxane compound, and w is the formula weight of the organic substituent.
• the average content of the phenyl group in this modified polydimethylsiloxane compound can be determined by using the following formula (III).
• x is the average value of the mole fraction of the phenyl group-containing siloxane repeating unit to all the siloxane repeating units in the modified polydimethylsiloxane compound.
• the average content of the polyether group in this modified polydimethylsiloxane compound can be determined by using the following formula (IV).
• the HLB value is a value indicating the degree of affinity of a surfactant for water and oils, and defined as the following formula (V) according to a Griffin method.
• HLB value 20 ⁇ (total formula weight of hydrophilic portions/molecular weight) (V)
• the cellulose-based resin composition according to an exemplary embodiment may be added two or more modified silicone compounds which are different to each other in affinity for the cellulose derivative as the main component.
• the dispersibility of the modified silicone compound having a relatively low affinity (A1) is improved by the modified silicone compound having a relatively high affinity (A2), and thereby a cellulose-based resin composition having still more excellent shock resistance can be obtained.
• the total average content of organic substituents of the modified silicone compound having a relatively low affinity (A1) is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more, and preferably 15% by mass or less, and more preferably 10% by mass or less.
• the total average content of organic substituents of the modified silicone compound having a relatively high affinity (A2) is preferably 15% by mass or more, and more preferably 20% by mass or more, and preferably 90% by mass or less.
• the formulation ratio (mass ratio) of the modified silicone compound (A1) to the modified silicone compound (A2) can be set in the range of 10/90 to 90/10.
• the same repeating units may be linked sequentially, or different ones may be linked alternately or randomly.
• the modified silicone compound may have a branched structure.
• the number average molecular weight of the modified silicone compound is preferably 900 or more, more preferably 1000 or more, and preferably 1000000 or less, more preferably 300000 or less, and still more preferably 100000 or less.
• the number average molecular weight of the modified silicone compound is sufficiently large, the loss of the modified silicone compound due to volatilization can be suppressed when a melted cellulose derivative and the modified silicone compound are kneaded together in producing the cellulose-based resin composition.
• the molecular weight of the modified silicone compound is not too large and moderate, the dispersibility of the modified silicone compound in the cellulose-based resin composition is good, and hence a molded article having a homogeneous composition can be obtained.
• the number average molecular weight of the modified silicone compound As the number average molecular weight of the modified silicone compound, a measurement (calibrated with a standard polystyrene sample) by GPC using 0.1% solution of a sample (modified silicone compound) in chloroform can be employed.
• the content of such a modified silicone compound is preferably 1% by mass or more, and more preferably 2% by mass or more based on the whole cellulose-based resin composition in view of obtaining a sufficient effect of the addition.
• the content of the modified silicone compound is preferably 20% by mass or less, and more preferably 10% by mass or less.
• Adding such a modified silicone compound to the cellulose-based resin composition enables to disperse the modified silicone compound in the resin composition in an appropriate particle diameter (e.g., 0.1 to 100 ⁇ m), and hence the shock resistance of the molded object can be enhanced.
• an appropriate particle diameter e.g., 0.1 to 100 ⁇ m
• a cellulose-based resin composition may be added as necessary an additive commonly applied to a cellulose-based resin composition such as a colorant, an antioxidant and a heat stabilizer.
• cellulose-based resin composition may be added as necessary a common thermoplastic resin.
• thermoplastic resin excellent in flexibility such as a thermoplastic polyurethane elastomer (TPU)
• TPU thermoplastic polyurethane elastomer
• the content of such a thermoplastic resin (particularly, a TPU) is preferably 1% by mass or more, and more preferably 5% by mass or more based on the whole cellulose-based resin composition in view of obtaining a sufficient effect of the addition.
• the content of this thermoplastic resin (particularly, a TPU) is preferably 20% by mass or less, and more preferably 15% by mass or more.
• thermoplastic polyurethane elastomer (TPU) suitable for enhancing shock resistance those prepared by using a polyol, a diisocyanate and a chain extender can be used.
• polystyrene resin examples include a polyester polyol, a polyester ether polyol, polycarbonate polyol and a polyether polyol.
• polyester polyol examples include polyester polyols obtained by dehydration condensation reaction of a polycarboxylic acid such as an aliphatic dicarboxylic acid (such as succinic acid, adipic acid, sebacic acid and azelaic acid), an aromatic dicarboxylic acid (phthalic acid, terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid) and an alicyclic dicarboxylic acid (hexahydrophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid) or an acid ester or an acid anhydride thereof, with a polyalcohol such as ethylene glycol, 1,3-propanediol (HO—CH 2 CH 2 CH 2 —OH), 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanedio
• polyester ether polyol examples include compounds obtained by dehydration condensation reaction of a polycarboxylic acid such as an aliphatic dicarboxylic acid (such as succinic acid, adipic acid, sebacic acid and azelaic acid), an aromatic dicarboxylic acid (phthalic acid, terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid) and an alicyclic dicarboxylic acid (hexahydrophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid) or an acid ester or an acid anhydride thereof, with diethylene glycol or a glycol such as an alkylene oxide adduct (such as a propylene oxide adduct) or a mixture thereof.
• a polycarboxylic acid such as an aliphatic dicarboxylic acid (such as succinic acid, adipic acid, sebacic acid and azelaic acid), an aromatic
• polycarbonate polyol examples include polycarbonate polyols obtained by reacting one or two or more polyalcohols such as ethylene glycol, 1,3-propanediol (HO—CH 2 CH 2 CH 2 —OH), 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol and diethylene glycol, with diethylene carbonate, dimethyl carbonate, diethyl carbonate or the like.
• a copolymer of a polycaprolactone polyol (PCL) and a polyhexamethylene carbonate (PHL) may be used.
• polyether polyol examples include, for example, a polyethylene glycol, a polypropylene glycol and a polytetramethylene ether glycol which are obtained by polymerizing a cyclic ether such as ethylene oxide, propylene oxide and tetrahydrofuran, respectively, and a copolyether thereof.
• Examples of the diisocyanate used to form the TPU include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), tolidine diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylene diisocyanate (TMXDI), 1,8-diisocyanate methyloctane and dicyclohexylmethane diisocyanate (hydrogenated MDI; HMDI).
• MDI tolylene diisocyanate
• MDI 4,4′-diphenylmethane diisocyanate
• HDI 1,6-hexamethylene diisocyanate
• a low-molecular weight polyol can be used as the chain extender used to form the TPU.
• the low-molecular weight polyol include aliphatic polyols such as ethylene glycol, 1,3-propanediol (HO—CH 2 CH 2 CH 2 —OH), 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, 1,4-cyclohexanedimethanol and glycerin; and aromatic glycols such as 1,4-dimethylolbenzene, bisphenol A and an ethylene oxide or propylene oxide adduct of bisphenol A.
• a molded object to be prepared from the cellulose-based resin composition with this copolymer added thereto can be provided with further excellent shock resistance.
• thermoplastic polyurethane elastomers may be used singly or in combination.
• the method for preparing a cellulose-based resin composition by adding the additives and the thermoplastic resin to the cellulose derivative according to an exemplary embodiment is not particularly limited, and for example, a cellulose-based resin composition can be prepared by melt-blending the additives and the cellulose derivative by using hand-mixing or a compounding machine such as a known mixer, for example, a tumbler mixer, a ribbon blender, a uniaxial or multiaxial mixing extruder, a kneader and a kneading roll, and as necessary performing, for example, granulation into an appropriate shape.
• a known mixer for example, a tumbler mixer, a ribbon blender, a uniaxial or multiaxial mixing extruder, a kneader and a kneading roll, and as necessary performing, for example, granulation into an appropriate shape.
• a coagulating solvent is added thereto to obtain a mixture composition of the additives and the cellulose derivative, and thereafter the solvent is evaporated to afford a cellulose-based resin composition.
• the cellulose derivative according to an exemplary embodiment described above can be used as a base resin for a molding material (resin composition).
• the molding material using the cellulose derivative as the base resin is suitable for molded objects such as a housing such as an outer package for an electronical device.
• base resin means a main component in a molding material (resin composition), and that it is acceptable for a base resin to contain other components in such a range that the function of the main component is not inhibited.
• content fraction of the main component (base resin) is not particularly specified, the exemplary embodiment is intended to encompass the cases that the content fraction of the main component (base resin) is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more.
• the content of the cellulose derivative according to the exemplary embodiment of the present invention can be selected to be in the range of 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more based on the whole cellulose-based resin composition.
• the aqueous layer was separated and discarded by using a separating funnel, and the ether layer was washed twice with 400 mL of distilled water. Anhydrous magnesium sulfate was added to the ether layer for drying, and thereafter was filtered off. The filtrate (ether layer) was concentrated in an evaporator (90° C./3 mmHg) under a reduced pressure to afford a crude product in a yellowish brown powder as a solid content. The obtained crude product was recrystallized from n-hexane and dried in vacuum.
• the hydrogenated cardanoxyacetic acid obtained in Synthesis Example 1 was mixed with acetic anhydride and heated to afford a mixed acid anhydride 1 (hydrogenated cardanoxyacetic acid-acetic acid mixed acid anhydride, CH 3 (CH 2 ) 14 —C 6 H 4 —O—CH 2 —CO—O—CO—CH 3 ).
• the mixed acid anhydride 1 was made according to the following procedure.
• the obtained mixture 1 was analyzed by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz). The result showed that the molar ratio of acetic anhydride, the mixed acid anhydride 1, hydrogenated cardanoxyacetic anhydride, hydrogenated cardanoxyacetic acid and acetic acid contained in the mixture 1 was, in this order, 43.0:20.8:2.0:10.0:24.2.
• a mixed acid anhydride 2 (stearic acid-acetic acid mixed acid anhydride, CH 3 (CH 2 ) 16 CO—O—CO—CH 3 ).
• the mixed acid anhydride 2 was made according to the following procedure.
• the obtained mixture 2 was analyzed by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz). The result showed that the molar ratio of acetic anhydride, the mixed acid anhydride 2, stearic anhydride, stearic acid and acetic acid contained in the mixture 2 was, in this order, 40.0:23.5:3.0:6.6:26.9.
• an activation treatment for cellulose was performed according to the following method.
• a cellulose derivative was synthesized according to the following method.
• the above activation-treated cellulose was dispersed in 150 mL of dry pyridine. To this dispersion was added 3.0 g of dimethylaminopyridine (DMAP) and the mixture 1 containing the mixed acid anhydride 1 obtained in Synthesis Example 2, and stirred at 100° C. for 15 hours while heating. Subsequently, 1.5 L of methanol was added to the reaction solution to reprecipitate a solid, which was then filtered off. The solid content filtered off was washed twice with 150 ml of isopropyl alcohol at 60° C., and thereafter dried at 105° C. for 5 hours under vacuum. Thereby, 17.5 g of a long-chain/short-chain-bonded cellulose derivative was obtained.
• DMAP dimethylaminopyridine
• the DS LO in the above IR measurement was calculated by using the strength of the contraction peak (1586 cm ⁇ 1 ) derived from the benzene ring backbone.
• the DS SH in the IR measurement was defined as a value obtained by subtracting the DS LO from the total amount of acyl group introduced (the total degree of substitution: DS SH +DS LO ) determined by using the strength of the C ⁇ O contraction peak (1750 cm ⁇ 1 ) derived from the ester linkage. These peak strengths were normalized against the strength of the contraction peak (1050 cm ⁇ 1 ) derived from the ether linkage in the glucopyranose ring.
• the relationship between the degree of substitution and the peak strength was calibrated by using a reference material (the DS SH and the DS LO thereof can be calculated by using NMR) synthesized from acetylcellulose (2,6-diacetylcellulose) and hydrogenated cardanoxyacetyl chloride.
• the DS SH and the DS LO of the soluble part were measured by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz), the result of which showed that the DS SH was 2.4 and the DS LO was 0.5.
• the melt flow rate (MFR) of the obtained cellulose derivative was measured by using a flow tester (manufactured by Shimadzu Corporation, product name: CFT-500D).
• the size of the die used, the measuring temperature, the pre-heating duration and the load were set to 10 ⁇ 2 mm ⁇ , 200° C., 120 seconds and 500 kgf/cm 2 (49 MPa), respectively.
• Press molding was performed under the following conditions to obtained a molded object, and the moldability in the press molding was evaluated according to the following criteria.
• size of molded object thickness: 2 mm, width: 13 mm, length: 80 mm.
• ⁇ good
• ⁇ poor (generation of a void, a sink or a partial unfilled part)
• x unmoldable.
• a flexural test was performed for the molded object obtained by above molding in accordance with JIS K7171 (flexural strength, modulus of elasticity in flexure).
• the activation treatment for cellulose was performed according to the same procedure as in Example 1.
• a long-chain/short-chain-bonded cellulose derivative was made according to the same procedure as in Example 1 except that N-methylpyrrolidinone (NMP) was used in place of dry pyridine as a solvent used in synthesizing a cellulose derivative (acylation).
• NMP N-methylpyrrolidinone
• 17.6 g of a long-chain/short-chain-bonded cellulose derivative was obtained from the starting raw material (the cellulose content was 6.0 g (0.037 mol/glucose unit)).
• the degree of substitution with short-chain acyl group (DS SH ) and the degree of substitution with long-chain acyl group (DS LO ) of the obtained long-chain/short-chain-bonded cellulose derivative were measured by using IR (manufactured by JASCO Corporation, product name: FT/IR-4100) according to the measuring method described in Example 1.
• the DS SH and the DS LO of the soluble part were measured by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz), the result of which showed that the DS SH was 2.4 and the DS LO was 0.6.
• the activation treatment for cellulose was performed according to the same procedure as in Example 1.
• a long-chain/short-chain-bonded cellulose derivative was made according to the same procedure as in Example 1 except that dimethylformamide (DMF) was used in place of dry pyridine as a solvent used in synthesizing a cellulose derivative (acylation). As the result, 18.1 g of a long-chain/short-chain-bonded cellulose derivative was obtained from the starting raw material (the cellulose content was 6.0 g (0.037 mol/glucose unit)).
• DMF dimethylformamide
• the degree of substitution with short-chain acyl group (DS SH ) and the degree of substitution with long-chain acyl group (DS LO ) of the obtained long-chain/short-chain-bonded cellulose derivative were measured by using IR (manufactured by JASCO Corporation, product name: FT/IR-4100) according to the measuring method described in Example 1.
• the DS SH and the DS LO of the soluble part were measured by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz), the result of which showed that the DS SH was 2.3 and the DS LO was 0.7.
• the activation treatment for cellulose was performed according to the same procedure as in Example 1.
• a long-chain/short-chain-bonded cellulose derivative was made according to the same procedure as in Example 1 except that dimethylacetamide (DMAc) was used in place of dry pyridine as a solvent used in synthesizing a cellulose derivative (acylation). As the result, 17.7 g of a long-chain/short-chain-bonded cellulose derivative was obtained from the starting raw material (the cellulose content was 6.0 g (0.037 mol/glucose unit)).
• DMAc dimethylacetamide
• the degree of substitution with short-chain acyl group (DS SH ) and the degree of substitution with long-chain acyl group (DS LO ) of the obtained long-chain/short-chain-bonded cellulose derivative were measured by using IR (manufactured by JASCO Corporation, product name: FT/IR-4100) according to the measuring method described in Example 1.
• the DS SH and the DS LO of the soluble part were measured by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz), the result of which showed that the DS SH was 2.4 and the DS LO was 0.6.
• the activation treatment for cellulose was performed according to the same procedure as in Example 1.
• a long-chain/short-chain-bonded cellulose derivative was made according to the same procedure as in Example 1 except that dioxane was used in place of dry pyridine as a solvent used in synthesizing a cellulose derivative (acylation). As the result, 7.3 g of a long-chain/short-chain-bonded cellulose derivative was obtained from the starting raw material (the cellulose content was 6.0 g (0.037 mol/glucose unit)).
• the degree of substitution with short-chain acyl group (DS SH ) and the degree of substitution with long-chain acyl group (DS LO ) of the obtained long-chain/short-chain-bonded cellulose derivative were measured by using IR (manufactured by JASCO Corporation, product name: FT/IR-4100) according to the measuring method described in Example 1.
• the DS SH and the DS LO thereof could not be measured by using 1 H-NMR.
• DMSO dimethylsulfoxide
• a long-chain/short-chain-bonded cellulose derivative was made according to the same procedure as in Example 1 except that N-methylpyrrolidinone (NMP) was used in place of dry pyridine as a solvent used in synthesizing a cellulose derivative (acylation).
• NMP N-methylpyrrolidinone
• 21.2 g of a long-chain/short-chain-bonded cellulose derivative was obtained from the starting raw material (the cellulose content was 6.0 g (0.037 mol/glucose unit)).
• the degree of substitution with short-chain acyl group (DS SH ) and the degree of substitution with long-chain acyl group (DS LO ) of the obtained long-chain/short-chain-bonded cellulose derivative were measured by using IR (manufactured by JASCO Corporation, product name: FT/IR-4100) according to the measuring method described in Example 1.
• the DS SH and the DS LO of the soluble part were measured by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz), the result of which showed that the DS SH was 2.1 and the DS LO was 0.9.
• a long-chain/short-chain-bonded cellulose derivative was made according to the same procedure as in Example 1 except that the mixture 2 containing the mixed acid anhydride 2 obtained in Synthesis Example 3 was used in place of the mixture 1 containing the mixed acid anhydride 1 obtained in Synthesis Example 2 as a mixture containing a mixed acid anhydride used in synthesizing a cellulose derivative (acylation), and NMP was used in place of dry pyridine as a solvent.
• 10.2 g of a long-chain/short-chain-bonded cellulose derivative was obtained from the starting raw material (the cellulose content was 6.0 g (0.037 mol/glucose unit)).
• the degree of substitution with short-chain acyl group (DS SH ) and the degree of substitution with long-chain acyl group (DS LO ) thereof cannot be measured by using the measurement method with IR described in Example 1.
• the DS SH and the DS LO of the soluble part were measured by using 1 H-NMR (manufactured by Bruker Corporation, product name: AV-400, 400 MHz), the result of which showed that the DS SH was 2.9 and the DS LO was 0.1.
• thermoplasticity press moldability
• Example 1 Short-chain (SH) Type acetyl acetyl acetyl acetyl acetyl acetyl component Amount of charge 12 12 12 12 12 12 (in terms of DS) Long-chain (LO) Type hydroge- hydroge- hydroge- hydroge- hydroge- hydroge- stearoyl component nated nated nated nated nated cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- cardanoxy- acetyl acetyl acetyl acetyl acetyl acetyl acetyl acetyl Amount of charge 3 3 3 3 3 (in terms of DS) Activation solvent for cellulose water/ water/ water/ water/ water/ DMSO water/ acetic acetic acetic acetic
• Example 5 As is clear from comparison of Examples 1 to 4 with Example 5, it can be seen that using a solvent having a large electron pair-donating property (Dn) makes the degree of substitution with long-chain acyl group (DS LO ) higher to provide a short-chain/long-chain-bonded cellulose derivative excellent in thermoplasticity and strength properties. Further, as is clear from comparison of Example 2 with Example 6, it can be seen that using dimethylsulfoxide as the activation solvent for cellulose provides a cellulose derivative having higher DS LO .
• Dn electron pair-donating property
• DS LO long-chain acyl group

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