Process for preparing esterified polysaccharides

Abstract

Provided is a method for producing an esterified polysaccharide capable of recycling a recovery liquid containing an onium salt by removing or reducing a carboxylic acid and substantially without the use of a catalyst for esterifying cellulose. A method for preparing an esterified polysaccharide comprises the following steps (1) to (8): (1) dissolving a polysaccharide in an onium salt, (2) adding an esterifying agent, (3) adding a solvent to precipitate the esterified polysaccharide, (4) filtering the esterified polysaccharide, (5) removing the solvent from the filtrate, (6) adding an amine to separate the onium salt from the amine-carboxylate, (7) recovering the onium salt, and (8) recycling the recovered onium salt.

Description

Technical Field

[0001] The present invention relates to a method for preparing an esterified polysaccharide. Background Art

[0002] There is a demand for protecting and maintaining the global or natural environment, and also for chemical substances and functional materials to impose a small burden on the environment or to be able to reduce the environmental burden. As such chemical substances and functional materials, natural polymers, particularly polysaccharides or polysaccharide derivatives, have been receiving attention.

[0003] Among polysaccharides, cellulose is used for membranes, fibers, pharmaceutical applications, etc. Cellulose derivatives are also widely used for commercial purposes.

[0004] Generally, cellulose is a β-1,4-linked polymer of dehydrated glucose, where glucose is used as a constituent unit.

[0005] A cellulose derivative is a compound in which at least a part of the three hydroxyl groups present in each glucose unit constituting cellulose is derivatized into other functional groups.

[0006] Esterified cellulose products obtained by esterifying cellulose and esterified cellulose derivative products obtained by esterifying the remaining hydroxyl groups in cellulose derivatives are also widely used for commercial purposes.

[0007] As a method for producing an esterified cellulose product, for example, Patent Document PTL 1 discloses a method for producing a cellulose ester, which includes dissolving cellulose in a carboxylated ionic liquid, contacting the cellulose solution with an acylating reagent in the presence of a catalyst to prepare a solution containing the cellulose ester, contacting the solution with a non-solvent to precipitate the cellulose ester, separating the precipitated cellulose ester from the carboxylated ionic liquid to recover the cellulose ester, and recycling the separated carboxylated ionic liquid for dissolving cellulose.

[0008] Citation List Patent Document PTL 1: JP2010-518244A Summary of the Invention

[0009] Technical Problem The method for manufacturing a cellulose ester disclosed in PTL 1 uses an acylating reagent to esterify cellulose and further uses a catalyst, i.e., methanesulfonic acid as a protonic acid, to increase the esterification rate.

[0010] The catalyst is considered to remain in the esterified cellulose, and in the case where the catalyst remains, it may affect the quality of the esterified cellulose used as a product.

[0011] In addition, since an acylating agent, i.e., acetic anhydride, is used and acetic acid remains after cellulose acylation, methanol is added to remove the residual acetic acid as methyl acetate. However, removing or reducing the remaining acetic acid is considered insufficient, and further removal or reduction of acetic acid is required to recycle the carboxylated ionic liquid.

[0012] Therefore, the problem is that a catalyst is needed to esterify cellulose and further removal or reduction of acetic acid is required.

[0013] In view of the current state of the art, an object of the present invention is to provide a method for preparing an esterified polysaccharide, preferably a method for preparing an esterified cellulose, which method is capable of further removing or reducing a carboxylic acid substantially without using a catalyst for esterifying cellulose.

[0014] Solution The inventors have conducted extensive research on a method for preparing an esterified polysaccharide, which method is capable of further removing or reducing a carboxylic acid substantially without using a catalyst for esterifying cellulose, and have completed the present invention.

[0015] Specifically, the present invention provides the following [1] to [7]. [1] A method for preparing an esterified polysaccharide, comprising the following steps (1) to (8): Step (1) Mixing an onium salt represented by formula (1) with a polysaccharide to dissolve the polysaccharide in the onium salt: Formula (1):

[0017] Wherein R 1 and R 2 are the same or different and each represents a hydrocarbon group optionally containing a heteroatom, R 1 and R 2 may contain a branched and / or cyclic structure and / or a double bond, R 3 represents a hydrogen atom or a C1-C5 hydrocarbon group, and R 4 represents a C1-C 12 hydrocarbon group and may contain a heteroatom, a double bond, a branched structure and / or a cyclic structure; Step (2) Adding an esterifying agent represented by formula (2) or formula (3) to the mixture obtained in step (1) to produce an esterified polysaccharide: Formula (2):

[0018] Wherein R5 represents a C1-C 12 hydrocarbyl group and may contain heteroatoms, double bonds, branched structures, and / or cyclic structures, Formula (3):

[0019] wherein R 5 represents a C1-C 12 hydrocarbyl group and may contain heteroatoms, double bonds, branched structures, and / or cyclic structures, and R 6 represents a hydrogen atom or a methyl group; Step (3): Add at least one selected from water, alcohols, and ketone solvents to the mixture obtained in Step (2) to precipitate the esterified polysaccharide, wherein the esterified polysaccharide is insoluble in the solvent; Step (4): Filter the esterified polysaccharide precipitated in Step (3) to separate the esterified polysaccharide from the filtrate, the filtrate containing the onium salt represented by Formula (1), the carboxylic acid represented by Formula (4), and the solvent in which the esterified polysaccharide is insoluble: Formula (4):

[0020] wherein R 5 represents a C1-C 12 hydrocarbyl group and may contain heteroatoms, double bonds, branched structures, and / or cyclic structures; Step (5): Heat and / or reduce the pressure of the filtrate separated in Step (4) to remove the solvent in which the esterified polysaccharide is insoluble from the filtrate; Step (6): Add the amine represented by Formula (5) to the mixture containing the onium salt represented by Formula (1) and the carboxylic acid represented by Formula (4) obtained in Step (5) to produce an amine-carboxylate salt, and separate the onium salt-containing layer from the amine-carboxylate salt-containing layer: Formula (5):

[0021] wherein R 7 , R 8 and R 9 may be the same or different and each represents a hydrogen atom or a C1-C 18 hydrocarbyl group and may contain double bonds, branched structures, and / or cyclic structures, and R 7 , R 8 and R 9 the total number of carbon atoms in is 8 or more; Step (7): Recover the onium salt-containing layer separated in Step (6) as the onium salt recovery liquid; and Step (8) introduces the recycled liquid recovered in step (7) into step (1). [2] The method for preparing an esterified polysaccharide according to [1], wherein in step (6), water and / or a hydrophilic solvent is added to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) obtained in step (5). [3] The method for preparing an esterified polysaccharide according to [1], wherein in step (6), either (i) an amine represented by formula (5), or (ii) an amine solution in which the amine is diluted with a hydrophobic solvent, is added to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) obtained in step (5). [4] The method for preparing an esterified polysaccharide according to [1], wherein in step (1), the onium salt represented by formula (1) has at least two types. [5] The method for preparing an esterified polysaccharide according to [1], wherein in step (2), the esterifying agent represented by formula (2) or formula (3) has at least two types. [6] The method for preparing an esterified polysaccharide according to [1], wherein in step (1), the onium salt represented by formula (1) is in the form of an onium salt solution, wherein the onium salt is diluted with an aprotic polar solvent. [7] The method for preparing an esterified polysaccharide according to [1], wherein in step (7), an amine represented by formula (5) is added to the onium salt-containing recovered liquid to produce an amine-carboxylate salt, the onium salt-containing layer is separated from the amine-carboxylate salt-containing layer, and the separated onium salt-containing layer is recovered as the onium salt-containing recovered liquid.

[0028] Advantages of the present invention According to the present invention, a method for producing an esterified polysaccharide can be provided, which can further remove or reduce carboxylic acid substantially without using a catalyst for esterifying cellulose, and the recovered liquid containing an onium salt recovered by this production method can be recycled. Detailed embodiments

[0029] The present invention will be specifically described below. One embodiment of the present invention relates to a method for preparing an esterified polysaccharide, comprising the following steps (1) to (8): Step (1): Mix the onium salt represented by formula (1) with the polysaccharide to dissolve the polysaccharide in the onium salt: Formula (1):

[0030] where R 1 and R 2 are the same or different and each represents a hydrocarbon group optionally containing a heteroatom, R 1 and R 2 may contain a branched and / or cyclic structure and / or a double bond, R 3 represents a hydrogen atom or a C1-C5 hydrocarbon group, and R 4 represents a C1-C 12 hydrocarbon group and may contain a heteroatom, a double bond, a branched structure and / or a cyclic structure; Step (2): Add an esterifying agent represented by formula (2) or formula (3) to the mixture obtained in step (1) to produce an esterified polysaccharide: Formula (2):

[0031] where R 5 represents a C1-C 12 hydrocarbon group and may contain a heteroatom, a double bond, a branched structure and / or a cyclic structure, Formula (3):

[0032] where R 5 represents a C1-C 12 hydrocarbon group and may contain a heteroatom, a double bond, a branched structure and / or a cyclic structure, and R 6 represents a hydrogen atom or a methyl group; Step (3): Add at least one solvent selected from water, alcohols and ketones to the mixture obtained in step (2) to precipitate the esterified polysaccharide, wherein the esterified polysaccharide is insoluble in the solvent; Step (4): Filter the esterified polysaccharide precipitated in step (3) to separate the esterified polysaccharide from the filtrate, the filtrate containing the onium salt represented by formula (1), the carboxylic acid represented by formula (4) and the solvent in which the esterified polysaccharide is insoluble: Formula (4):

[0033] where R 5represents C1-C 12 hydrocarbyl group and may contain heteroatoms, double bonds, branched structures, and / or cyclic structures; Step (5): Heating and / or reducing the pressure of the filtrate separated in step (4) to remove the solvent insoluble in the esterified polysaccharide from the filtrate; Step (6): Adding the amine represented by formula (5) to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) obtained in step (5) to produce an amine-carboxylate salt, and separating the onium salt-containing layer from the amine-carboxylate salt-containing layer: Formula (5):

[0034] wherein R 7 、R 8 and R 9 may be the same or different and each represents a hydrogen atom or a C1-C 18 hydrocarbyl group, and may contain double bonds, branched structures, and / or cyclic structures, and R 7 、R 8 and R 9 the total number of carbon atoms in is 8 or more; Step (7): Recycling the onium salt-containing layer separated in step (6) as the onium salt-containing recovered liquid; and Step (8): Introducing the recovered liquid recovered in step (7) into step (1).

[0035] The onium salt represented by formula (1) used in step (1) is at least one type or at least two types, such as 2 to 5 types, 2 to 4 types, 2 to 3 types, or 2 types.

[0036] The esterifying agent represented by formula (2) or formula (3) used in step (2) is at least one type or at least two types, such as 2 to 5 types, 2 to 4 types, 2 to 3 types, or 2 types.

[0037] In step (1), the polysaccharide may be mixed with an onium salt solution, wherein at least one onium salt represented by formula (1) is diluted with at least one aprotic polar solvent.

[0038] The onium salt represented by the following formula (1) used in step (1) of the production method of the present invention will be explained below.

[0039] Formula (1):

[0040] The onium salt represented by formula (1) is formed by an imidazolium cation represented by formula (1-1) and a carboxylate anion represented by formula (1-2).

[0041] Formula (1-1):

[0042] Formula (1-2):

[0043] The imidazolium cation represented by the following formula (1-1) is explained below.

[0044] Formula (1-1):

[0045] In Formula (1) and Formula (1-1), R 1 and R 2 are the same or different and each represents a hydrocarbon group optionally containing a heteroatom. R 1 and R 2 may contain a branched chain and / or a cyclic structure and / or a double bond. R 3 is a hydrogen atom or a C1-C5 hydrocarbon group.

[0046] The embodiments in which R 1 and R 2 in Formula (1) and Formula (1-1) are each a hydrocarbon group without a heteroatom are explained below.

[0047] In Formula (1) and Formula (1-1), when R 1 and R 2 are each a hydrocarbon group without a heteroatom, the number of carbon atoms in the hydrocarbon group is preferably 1 to 12, more preferably 1 to 8, even more preferably 1 to 3. The hydrocarbon group may be straight-chain and may contain a branched chain and / or a cyclic structure and / or a double bond.

[0048] In Formula (1) and Formula (1-1), examples of the "hydrocarbon group without a heteroatom" of R 1 and R 2 include a straight-chain or branched-chain alkyl group without a heteroatom, a straight-chain or branched-chain alkenyl group without a heteroatom, a straight-chain or branched-chain alkynyl group without a heteroatom, a branched-chain cycloalkyl group optionally without a heteroatom, a branched-chain cycloalkenyl group optionally without a heteroatom, a branched-chain aryl group optionally without a heteroatom, and a branched-chain aralkyl group optionally without a heteroatom.

[0049] Preferred are a straight-chain or branched-chain alkyl group without a heteroatom, a straight-chain or branched-chain alkenyl group without a heteroatom, and a branched-chain cycloalkyl group optionally without a heteroatom.

[0050] In Formula (1) and Formula (1-1), the "straight-chain or branched-chain alkyl group without a heteroatom" of R 1 and R 2 is preferably a straight-chain or branched-chain C1-C 12An alkyl group, more preferably a straight-chain or branched C1-C8 alkyl group without heteroatoms, even more preferably a straight-chain or branched C1-C4 alkyl group without heteroatoms, still more preferably a straight-chain or branched C1-C3 alkyl group without heteroatoms.

[0051] In formulas (1) and (1-1), R 1 and R 2 's "straight-chain or branched alkenyl group without heteroatoms" is preferably a straight-chain or branched C2-C 12 alkenyl group, more preferably a straight-chain or branched C2-C8 alkenyl group without heteroatoms, even more preferably a straight-chain or branched C2-C4 alkenyl group without heteroatoms, still more preferably a straight-chain or branched C2-C3 alkenyl group without heteroatoms.

[0052] In formulas (1) and (1-1), R 1 and R 2 's "optionally branched cycloalkyl group without heteroatoms" is preferably an optionally branched C3-C 12 cycloalkyl group, more preferably an optionally branched C3-C8 cycloalkyl group without heteroatoms, even more preferably an optionally branched C3-C4 cycloalkyl group without heteroatoms, still more preferably a C3 cycloalkyl group.

[0053] In formula (1-1), R 1 and R 2 's specific examples of "hydrocarbon group without heteroatoms" include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, vinyl, ethynyl, propenyl, isopropenyl, allyl, propargyl, butenyl, crotyl, butadienyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, phenyl, benzyl, tolyl, styryl, 2,4,6-trimethylphenyl. The hydrocarbon group without heteroatoms is preferably methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, more preferably methyl, ethyl, propyl, isopropyl, tert-butyl.

[0054] The following explains the embodiments in which R 1 and R 2 in formulas (1) and (1-1) are each a hydrocarbon group containing heteroatoms.

[0055] In formulas (1) and (1-1), when R 1 and R 2 are each a hydrocarbon group containing heteroatoms, the number of carbon atoms is preferably 2 to 12, more preferably 2 to 8, even more preferably 2 to 4. The hydrocarbon group can be straight-chain and can contain branches and / or cyclic structures and / or double bonds.

[0056] In Formulas (1) and (1-1), when R 1 and R 2 are each a hydrocarbon group containing a heteroatom, examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. The number of heteroatoms is preferably 1 to 5, and more preferably 1 or 2.

[0057] In Formulas (1) and (1-1), the "hydrocarbon group containing a heteroatom" of R 1 and R 2 means that in a hydrocarbon group without a heteroatom, (i) the bond between two adjacent carbon atoms and / or (ii) the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) are replaced by a structure such as -O-, -N<, -NH-, -S-, -C(=O)-O-, -C(=O)-, =N-, -C(=O)-N<, -C(=O)-NH-, -O-C(=O)-O-, -O-C(=O)-N<, -O-C(=O)-NH-, -C(=O)-N[-C(=O)-]-, -C(=O)-NH-C(=O)-, >N-C(=O)-N<, >N-C(=O)-NH-, -HN-C(=O)-NH-, -S(=O)-, -S(=O)2-, -S(=O)2-O-, -O-S(=O)2-O-, >N-C(=S)-N<, >N-C(=S)-NH-, -HN-C(=S)-NH-, -C(=N-)-, or -C(=NH)- to form a hydrocarbon group. The number and combination of substitutions of these structures are not particularly limited; however, the number of heteroatoms in R 1 and R 2 is preferably 1 to 5, more preferably 1 or 2.

[0058] Preferably, the heteroatom-containing hydrocarbon group is a hydrocarbon group formed by replacing (i) the bond between two adjacent carbon atoms and / or (ii) the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) in the hydrocarbon group with -O- or -S-, more preferably -O-.

[0059] In the present invention, the structure in which (i) the bond between two adjacent carbon atoms and / or (ii) the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) in the hydrocarbon group are replaced by -O- or -S- can be not only an -O- structure (ether structure) or an -S- structure (thioether structure), but also an epoxy structure or a thioepoxy structure, such as an epoxy group, a thioepoxy group, a glycidyl ether group, or a cyclohexyl epoxy group. In this case, R 1 and R 2 can be, for example, an epoxy group or a thioepoxy group.

[0060] When R 1 and R2 When there are two or more -O- and / or -S- structures, the number of carbon atoms between the -O- and / or -S- structures is preferably two or more.

[0061] In formulas (1) and (1-1), R 1 and R 2 Examples of the "heteroatom-containing hydrocarbon group" include a straight-chain or branched-chain alkyl group containing a heteroatom, a straight-chain or branched-chain alkenyl group containing a heteroatom, a straight-chain or branched-chain alkynyl group containing a heteroatom, an optionally branched cycloalkyl group containing a heteroatom, an optionally branched cycloalkenyl group containing a heteroatom, an optionally branched aryl group containing a heteroatom, and an optionally branched aralkyl group containing a heteroatom.

[0062] Preferred are a straight-chain or branched-chain alkyl group containing a heteroatom, a straight-chain or branched-chain alkenyl group containing a heteroatom, and an optionally branched cycloalkyl group containing a heteroatom.

[0063] The "straight-chain or branched-chain alkyl group containing a heteroatom" is preferably a straight-chain or branched-chain C1-C 12 alkyl group containing 1 to 5 heteroatoms.

[0064] In another embodiment, the straight-chain or branched-chain alkyl group containing a heteroatom is preferably a straight-chain or branched-chain C1-C 12 alkyl group containing 1 or 2 heteroatoms, more preferably a straight-chain or branched-chain C1-C8 alkyl group containing 1 or 2 heteroatoms, and even more preferably a straight-chain or branched-chain C1-C4 alkyl group containing 1 or 2 heteroatoms.

[0065] The "straight-chain or branched-chain alkenyl group containing a heteroatom" is preferably a straight-chain or branched-chain C2-C 12 alkenyl group containing 1 to 5 heteroatoms.

[0066] In another embodiment, the straight-chain or branched-chain alkenyl group containing a heteroatom is preferably a straight-chain or branched-chain C2-C 12 alkenyl group containing 1 or 2 heteroatoms, more preferably a straight-chain or branched-chain C2-C8 alkenyl group containing 1 or 2 heteroatoms, and even more preferably a straight-chain or branched-chain C2-C4 alkenyl group containing 1 or 2 heteroatoms.

[0067] The "optionally branched cycloalkyl group containing a heteroatom" is preferably an optionally branched C3-C 12 cycloalkyl group containing 1 to 5 heteroatoms.

[0068] In another embodiment, the optionally branched cycloalkyl group containing a heteroatom is preferably an optionally branched C3-C 12 cycloalkyl group containing 1 or 2 heteroatoms, more preferably an optionally branched C3-C8 cycloalkyl group containing 1 or 2 heteroatoms, and even more preferably an optionally branched C3-C4 cycloalkyl group containing 1 or 2 heteroatoms.

[0069] In formulas (1) and (1-1), R 1 and R 2Specific examples of the "heteroatom-containing hydrocarbon group" include, but are not limited to, 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-isopropoxyethyl, 2-phenoxyethyl, 2-(benzyloxy)ethyl, 2-(p-methoxybenzyloxy)ethyl, 2-(2-methoxyethoxymethoxy)ethyl, 2-(2-benzyloxyethoxy)ethyl, 2-(dimethylamino)ethyl, 3-methoxypropyl, 3-ethoxypropyl, 3-propoxypropyl, 3-allyloxypropyl, 3-isopropoxypropyl, 3-(1-methylpropoxy)propyl, 3-(2-methylpropoxy)propyl, 3-(1,1-dimethylethoxy)propyl, 3-butoxypropyl, 3-pentyloxypropyl, 3-neopentyloxypropyl, 3-hexyloxypropyl, 3-cyclohexyloxypropyl, 3-heptyloxypropyl, 3-octyloxypropyl, 3-nonyloxypropyl, 3-(2-ethylhex-1-yloxy)propyl, 3-(2,4,6-trimethylphenoxy)propyl, 3-(2-methoxyethoxy)propyl, 3-(dimethylamino)propyl, 4-methoxybutyl, 4-ethoxybutyl, 4-propoxybutyl, 4-isopropoxybutyl, 4-allyloxybutyl, 4-butoxybutyl, 4-(1-methylpropoxy)butyl, 4-(2-methylpropoxy)butyl, 4-(1,1-dimethylethoxy)butyl, 4-pentyloxybutyl, 4-neopentyloxybutyl, 4-hexyloxybutyl, 4-cyclohexyloxybutyl, 4-heptyloxybutyl, 4-octyloxybutyl, 4-(2-ethylhex-1-yloxy)butyl, 5-methoxypentyl, 5-ethoxypentyl, 5-propoxypentyl, 5-isopropoxypentyl, 5-allyloxypentyl, 5-butoxypentyl, 5-(1-methylpropoxy)pentyl, 5-(2-methylpropoxy)pentyl, 5-(1,1-(dimethyl ethoxy) pentyl, 5-pentyloxy pentyl, 5-neopentyloxy pentyl, 5-hexyloxy pentyl, 5-cyclohexyloxy pentyl, 5-heptyloxy pentyl, 6-methoxy hexyl, 6-ethoxy hexyl, 6-propoxy hexyl, 6-isopropoxy hexyl, 6-(1-methyl propoxy) hexyl, 6-(2-methyl propoxy) hexyl, 6-(1,1-dimethyl ethoxy) hexyl, 6-pentyloxy hexyl, 6-neopentyloxy hexyl, 6-hexyloxy hexyl, 6-cyclohexyloxy hexyl, (2-methoxy cyclohexane-1-yl) methyl, (2-ethoxy cyclohexane-1-yl) methyl, (2-propoxy cyclohexane-1-yl) methyl, (2-isopropoxy cyclohexane-1-yl) methyl, (2-butoxy cyclohexane-1-yl) methyl, [2-(1-methyl propoxy) cyclohexane-1-yl] methyl, [2-(2-methyl propoxy) cyclohexane-1-yl] methyl, [2-(1,1-dimethyl ethoxy) cyclohexane-1-yl] methyl, (2-pentyloxy cyclohexane-1-yl) methyl, (2-neopentyloxy cyclohexane-1-yl) methyl, 2-methylthio ethyl, 3-methylthio propyl, 1-(methoxy methyl) propyl, (oxolane-2-yl) methyl, (furan-2-yl) methyl, 2-[(furan-2-yl) methylthio] ethyl, 2-(methylsulfonyl) ethyl, (thiophen-2-yl) methyl, p-methoxyphenyl, p-ethoxyphenyl, 3,4-methylenedioxyphenyl, 3,4-methylenedioxybenzyl and (7-oxabicyclo[2,2,1] heptan-2-yl) methyl, etc. Preferred are 2-methoxy ethyl, 3-methoxy propyl, 3-ethoxy propyl, 3-isopropoxy propyl, 3-butoxy propyl, 3-(2-methoxy ethoxy) propyl, 3-methylthio propyl and 3-(dimethyl amino) propyl; More preferred are 2-methoxy ethyl, 3-methoxy propyl and 3-(2-methoxy ethoxy) propyl.,

[0070] In formulas (1) and (1-1), R 3 is a hydrogen atom or a C1-C5 hydrocarbon group. The number of carbon atoms of the hydrocarbon group is preferably 1 to 3. The hydrocarbon group can be straight-chain and can contain branches and / or cyclic structures, double bonds and / or triple bonds.,

[0071] In formulas (1) and (1-1), R 3 Examples of the "C1-C5 hydrocarbon group" of include, but are not limited to, alkyl, alkenyl, alkynyl and cycloalkyl.,

[0072] The alkyl is preferably a straight-chain or branched C1-C5 alkyl, more preferably a straight-chain or branched C1-C3 alkyl.,

[0073] The alkenyl is preferably a straight-chain or branched C2-C5 alkenyl, more preferably a straight-chain or branched C2-C3 alkenyl.,

[0074] The cycloalkyl group is preferably an optionally branched C3-C5 cycloalkyl group, more preferably a C3 cycloalkyl group.

[0075] In formula (1) and formula (1-1), R 3 Specific examples of the "C1-C5 hydrocarbyl group" include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, vinyl, ethynyl, propenyl, and isopropenyl. Methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, and neopentyl are preferred, and methyl, ethyl, propyl, isopropyl, and tert-butyl are more preferred.

[0076] In formula (1-1), specific examples of the imidazolium cation having a hydrocarbyl group free of heteroatoms include 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-methyl-3-propylimidazolium, 1-butyl-3-methylimidazolium, 1-methyl-3-pentylimidazolium, 1-hexyl-3-methylimidazolium, 1-heptyl-3-methylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-3-nonylimidazolium, 1-decyl-3-methylimidazolium, 1,3-diallylimidazolium, 1-allyl-3-methylimidazolium, and 1-allyl-3-ethylimidazolium. The imidazolium cation having a hydrocarbyl group free of heteroatoms is preferably 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, and 1-butyl-3-methylimidazolium, but the present invention is not limited to these compounds.

[0077] In formula (1-1), specific examples of the imidazolium cation having a hydrocarbon group containing a heteroatom include 1,3-bis(2-methoxyethyl)imidazolium, 1,3-bis(2-ethoxyethyl)imidazolium, 1,3-bis(2-propoxyethyl)imidazolium, 1,3-bis(2-isopropoxyethyl)imidazolium, 1,3-bis(2-phenoxyethyl)imidazolium, 1,3-bis(2-benzyloxyethyl)imidazolium, 1,3-bis[2-(p-methoxybenzyloxy)ethyl]imidazolium, 1,3-bis[2-(2-methoxyethoxymethoxy)ethyl]imidazolium, 1,3-bis[2-(2-benzyloxyethoxy)ethyl]imidazolium, 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1,3-bis(3-propoxypropyl)imidazolium, 1,3-bis(3-isopropoxypropyl)imidazolium, 1,3-bis(3-allyloxypropyl)imidazolium, 1,3-bis(3-butoxypropyl)imidazolium, 1,3-bis[3-(1-methylpropoxy)propyl]imidazolium, 1,3-bis[3-(2-methylpropoxy)propyl]imidazolium, 1,3-bis[3-(1,1-dimethylethoxy)propyl]imidazolium, 1,3-bis[(oxolan-2-yl)methyl]imidazolium, 1,3-bis(3-pentyloxypropyl)imidazolium, 1,3-bis(3-neopentyloxypropyl)imidazolium, 1,3-bis(3-hexyloxypropyl)imidazolium, 1,3-bis(3-cyclohexyloxypropyl)imidazolium, 1,3-bis(3-heptyloxypropyl)imidazolium, 1,3-bis(3-octyloxypropyl)imidazolium, 1,3-bis(3-nonyloxypropyl)imidazolium, 1,3-bis{3-[(2-ethylhexan-1-yl)oxy]propyl}imidazolium, 1,3-bis[3-(2,4,6-trimethylphenoxy)propyl]imidazolium, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium, 1,3-bis[2-(dimethylamino)ethyl]imidazolium, 1,3-bis[3-(dimethylamino)propyl]imidazolium, 1,3-bis(2-methylthioethyl)imidazolium, 1,3-bis{2-[(furan-2-yl)methylthio]ethyl]imidazolium, 1,3-bis[2-(furan-2-yl)methyl]imidazolium, 1,3-bis[1-(methoxymethyl)propyl]imidazolium, 1,3-bis(4-methoxybutyl)imidazolium, 1,3-bis(4-ethoxybutyl)imidazolium, 1,3-bis(4-propoxybutyl)imidazolium, 1,3-bis(4-isopropoxybutyl)imidazolium, 1,3-bis(4-allyloxybutyl)imidazolium, 1,3-bis(4-butoxybutyl)imidazolium, 1,3-bis[4-(1-methylpropoxy)butyl]imidazolium, 1,3-bis[4-(2-methylpropoxy)butyl]imidazolium, 1,3-bis[4-(1,1-dimethylethoxy)butyl]imidazolium, 1,3-bis(4-pentyloxybutyl)imidazolium, 1,3-bis(4-neopentyloxybutyl)imidazolium, 1,3-bis(4-hexyloxybutyl)imidazolium, 1,3-bis(4-cyclohexyloxybutyl)imidazolium, 1,3-bis(4-heptyloxybutyl)imidazolium, 1,3-di(4-octyloxybutyl)imidazolium, 1,3-di{4-[(2-ethylhexan-1-yl)oxy]butyl}imidazolium, 1,3-di(5-methoxypentyl)imidazolium, 1,3-di(5-ethoxypentyl)imidazolium, 1,3-di(5-propoxypentyl)imidazolium, 1,3-bis(5-isopropoxypentyl)imidazolium, 1,3-bis(5-allyloxypentyl)imidazolium, 1,3-bis(5-butoxypentyl)imidazolium, 1,3-bis[5-(1-methylpropoxy)pentyl]imidazolium, 1,3-bis[5-(2-methylpropoxy)pentyl]imidazolium, 1,3-bis[5-(1,1-dimethylethoxy)pentyl]imidazolium, 1,3-bis(5-pentyloxypentyl)imidazolium, 1,3-bis(5-neopentyloxypentyl)imidazolium, 1,3-bis(5-hexyloxypentyl)imidazolium, 1,3-di(5-cyclohexyloxypentyl)imidazolium, 1,3-di(5-heptyloxypentyl)imidazolium, 1,3-bis(6-methoxyhexyl)imidazolium, 1,3-di(6-ethoxyhexyl)imidazolium, 1,3-bis(6-propoxyhexyl)imidazolium, 1,3-bis(6-isopropoxyhexyl)imidazolium, 1,3-bis(6-allyloxyhexyl)imidazolium, 1,3-bis(6-butoxyhexyl)imidazolium, 1,3-bis[6-(1-methylpropoxy)hexyl]imidazolium, 1,3-bis[6-(2-methylpropoxy)hexyl]imidazolium, 1,3-bis[6-(1,1-dimethylethoxy)hexyl]imidazolium, 1,3-bis(6-pentyloxyhexyl)imidazolium, 1,3-bis(6-neopentyloxyhexyl)imidazolium, 1,3-bis(6-hexyloxyhexyl)imidazolium, 1,3-bis(6-cyclohexyloxyhexyl)imidazolium, 1,3-bis[(2-methoxycyclohexan-1-yl)methyl]imidazolium, 1,3-bis[(2-ethoxycyclohexan-1-yl)methyl]imidazolium, 1,3-bis[(2-propoxycyclohexan-1-yl)methyl]imidazolium, 1,3-bis[(2-isopropoxycyclohexan-1-yl)methyl]imidazolium, 1,3-bis[(2-butoxycyclohexan-1-yl)methyl]imidazolium, 1,3-bis{[2-(1-methylpropoxy)cyclohexan-1-yl]methyl}imidazolium, 1,3-bis{[2-(2-methylpropoxy)cyclohexan-1-yl]methyl}imidazolium, 1,3-bis{[2-(1,1-dimethylethoxy)cyclohexan-1-yl]methyl}imidazolium, 1,3-bis[(2-pentyloxycyclohexan-1-yl)methyl]imidazolium, 1,3-bis[(2-neopentyloxycyclohexan-1-yl)methyl]imidazolium, 1,3-bis(3-methylthiopropyl)imidazolium, 1,3-bis[2-(methylsulfonyl)ethyl]imidazolium, 1,3-bis[(thiophen-2-yl)methyl]imidazolium, 1,3-Bis(p-methoxyphenyl)imidazolium, 1,3-bis(p-ethoxyphenyl)imidazolium, 1,3-bis(3,4-methylenedioxyphenyl)imidazolium, 1,3-bis(3,4-methylenedioxybenzyl)imidazolium, 1,3-bis{(7-oxabicyclo[2,2,1]hept-2-yl)methyl}imidazolium, 1-methoxypropyl-3-methylthiopropylimidazolium, 1,3-bis(3-methoxypropyl)-2-methylimidazolium, and 1,3-bis(2-methoxyethyl)-2-methylimidazolium. The imidazolium cations having a hydrocarbon group containing a hetero atom are preferably 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1,3-bis(3-propoxypropyl)imidazolium, 1,3-bis(3-isopropoxypropyl)imidazolium, 1,3-bis(3-allyloxypropyl)imidazolium, 1,3-bis(3-butoxypropyl)imidazolium, 1,3-bis[3-(1-methylpropoxy)propyl]imidazolium, 1,3-bis[3-(2-methylpropoxy)propyl]imidazolium, 1,3-bis[3-(1,1-dimethylethoxy)propyl]imidazolium, 1,3-bis[(oxolane-2-yl)methyl]imidazolium, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium, 1,3-bis(3-methylthiopropyl)imidazolium, 1-methoxypropyl-3-methylthiopropylimidazolium, 1,3-bis(3-methoxypropyl)-2-methylimidazolium, or 1,3-bis(2-methoxyethyl)-2-methylimidazolium, more preferably 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1-methoxypropyl-3-methylthioimidazolium, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium, 1,3-bis(2-methoxyethyl)-2-methylimidazolium, or 1,3-bis(3-methoxypropyl)-2-methylimidazolium, but the present invention is not limited to these compounds.,

[0078] The carboxylate anion represented by the following formula (1-2) in the formula (1) is explained below.

[0079] Formula (1-2):

[0080] In the formulas (1) and (1-2), R 4 represents a C1-C 12 hydrocarbon group and may contain a hetero atom, a double bond, a branched structure, and / or a cyclic structure.

[0081] In the formulas (1) and (1-2), R 4 of the "C1-C 12 hydrocarbon group" preferably has 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms. The hydrocarbon may be straight-chain and may contain a branched and / or cyclic structure and / or a double bond.

[0082] In formulas (1) and (1-2), R 4 of "C1-C 12 hydrocarbyl" examples include linear or branched C1-C 12 alkyl, linear or branched C2-C 12 alkenyl, linear or branched C2-C 12 alkynyl, optionally branched C3-C 12 cycloalkyl, optionally branched C3-C 12 cycloalkenyl, optionally branched C6-C 12 aryl and optionally branched C7-C 12 aralkyl.

[0083] Preferably linear or branched C1-C 12 alkyl, linear or branched C2-C 12 alkenyl and optionally branched C3-C 12 cycloalkyl.

[0084] In formulas (1) and (1-1), R 4 of "linear or branched C1-C 12 alkyl" is preferably linear or branched C1-C8 alkyl, more preferably linear or branched C1-C4 alkyl, even more preferably linear or branched C1-C3 alkyl.

[0085] In formulas (1) and (1-1), R 4 of "linear or branched C2-C 12 alkenyl" is preferably linear or branched C2-C8 alkenyl, more preferably linear or branched C2-C4 alkenyl, even more preferably linear or branched C2-C3 alkenyl.

[0086] In formulas (1) and (1-1), R 4 of "optionally branched C3-C 12 cycloalkyl" is preferably optionally branched C3-C8 cycloalkyl, more preferably optionally branched C3-C4 cycloalkyl, even more preferably C3 cycloalkyl.

[0087] In formulas (1) and (1-2), R 4 of "C1-C 12 hydrocarbyl" specific examples include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, vinyl, ethynyl, propenyl, isopropenyl, allyl, propargyl, butenyl, crotyl, butadienyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, phenyl, benzyl, tolyl, styryl and 2,4,6-trimethylphenyl. C1-C 12The alkyl group is preferably methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, and hexyl, more preferably methyl, ethyl, propyl, isopropyl, and tert-butyl.

[0088] Among them, the R in Formula (1) and Formula (1-1) 4 The embodiments representing a hydrocarbon group containing a heteroatom are explained as follows.

[0089] In Formula (1) and Formula (1-2), when R 4 is a hydrocarbon group containing a heteroatom, the hydrocarbon group may be straight-chain and may contain branched chains and / or cyclic structures and / or double bonds.

[0090] In Formula (1) and Formula (1-2), when R 4 is a hydrocarbon group containing a heteroatom, the number of carbon atoms is preferably 2 to 12, more preferably 2 to 8, and even more preferably 2 to 4.

[0091] In Formula (1) and Formula (1-2), when R 4 is a hydrocarbon group containing a heteroatom, the number of heteroatoms is preferably 1 to 5, more preferably 1 to 2. Examples of heteroatoms include nitrogen atoms, oxygen atoms, and sulfur atoms.

[0092] In Formula (1) and Formula (1-2), R 4 The "hydrocarbon group containing a heteroatom" means that in a hydrocarbon group without a heteroatom, (i) the bond between two adjacent carbon atoms and / or (ii) the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) are replaced by structures such as -O-, -N<, -NH-, -S-, -C(=O)-O-, -C(=O)-, =N-, -C(=O)-N<, -C(=O)-NH-, -O-C(=O)-O-, -O-C(=O)-N<, -O-C(=O)-NH-, -C(=O)-N[-C(=O)-]-, -C(=O)-NH-C(=O)-, >N-C(=O)-N<, >N-C(=O)-NH-, -HN-C(=O)-NH-, -S(=O)-, -S(=O)2-, -S(=O)2-O-, -O-S(=O)2-O-, >N-C(=S)-N<, >N-C(=S)-NH-, -HN-C(=S)-NH-, -C(=N-)-, or -C(=NH)- to form a hydrocarbon group. The number and combination of these structural replacements are not particularly limited.

[0093] Preferably, the hydrocarbon group containing a heteroatom is a hydrocarbon group formed by (i) replacing the bond between two adjacent carbon atoms and / or (ii) replacing the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) in the hydrocarbon group with -O- or -S-, more preferably -O-.

[0094] R in formulas (1) and (1-2) 4 Among them, (i) the bond between two adjacent carbon atoms and / or (ii) the structure in which the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) in the hydrocarbon group are replaced by -O- or -S- can not only be an -O- structure (ether structure) or an -S- structure (thioether structure), but also an epoxy structure or a thioepoxy structure, such as an epoxy group, a thioepoxy group, a glycidyl ether group or a cyclohexyl epoxy group.

[0095] In formulas (1) and (1-2), when R 4 contains two or more -O- and / or -S- structures, the number of carbon atoms between the -O- and / or -S- structures is preferably two or more.

[0096] In formulas (1) and (1-2), examples of the "hydrocarbon group containing a heteroatom" of R 4 include a straight-chain or branched-chain alkyl group containing a heteroatom, a straight-chain or branched-chain alkenyl group containing a heteroatom, a straight-chain or branched-chain alkynyl group containing a heteroatom, a branched-chain cycloalkyl group optionally containing a heteroatom, a branched-chain cycloalkenyl group optionally containing a heteroatom, a branched-chain aryl group optionally containing a heteroatom, and a branched-chain aralkyl group optionally containing a heteroatom.

[0097] Preferred are a straight-chain or branched-chain alkyl group containing a heteroatom, a straight-chain or branched-chain alkenyl group containing a heteroatom, and a branched-chain cycloalkyl group optionally containing a heteroatom.

[0098] The "straight-chain or branched-chain alkyl group containing a heteroatom" is preferably a straight-chain or branched-chain C1-C 12 alkyl group containing 1 to 5 heteroatoms.

[0099] In another embodiment, the straight-chain or branched-chain alkyl group containing a heteroatom is preferably a straight-chain or branched-chain C1-C 12 alkyl group containing 1 or 2 heteroatoms, more preferably a straight-chain or branched-chain C1-C8 alkyl group containing 1 or 2 heteroatoms, and even more preferably a straight-chain or branched-chain C1-C4 alkyl group containing 1 or 2 heteroatoms.

[0100] The "straight-chain or branched-chain alkenyl group containing a heteroatom" is preferably a straight-chain or branched-chain C2-C 12 alkenyl group containing 1 to 5 heteroatoms.

[0101] In another embodiment, the straight-chain or branched-chain alkenyl group containing a heteroatom is preferably a straight-chain or branched-chain C2-C 12 alkenyl group containing 1 or 2 heteroatoms, more preferably a straight-chain or branched-chain C2-C8 alkenyl group containing 1 or 2 heteroatoms, and even more preferably a straight-chain or branched-chain C2-C4 alkenyl group containing 1 or 2 heteroatoms.

[0102] "Optionally branched cycloalkyl containing a heteroatom" is preferably optionally branched C3-C cycloalkyl containing 1 to 5 heteroatoms 12 cycloalkyl.

[0103] In another embodiment, the optionally branched cycloalkyl containing a heteroatom is preferably optionally branched C3-C cycloalkyl containing 1 or 2 heteroatoms 12 cycloalkyl, more preferably optionally branched C3-C8 cycloalkyl containing 1 or 2 heteroatoms, and even more preferably optionally branched C3-C4 cycloalkyl containing 1 or 2 heteroatoms.

[0104] In formulas (1) and (1-2), R 4 of "hydrocarbyl group containing a heteroatom" is preferably methoxymethyl, methoxyethyl, ethoxymethyl, propoxy or 2-methoxyethoxy, more preferably methoxymethyl, methoxyethyl or 2-methoxyethoxy, but the present invention is not limited to these groups.

[0105] In formulas (1) and (1-2), R 4 is preferably methyl, ethyl, methoxymethyl or methoxyethyl.

[0106] Specific examples of the carboxylate anion represented by formula (1-2) include: acetate ion, propionate ion, acrylate ion, propiolate ion, butyrate ion, isobutyrate ion, methacrylate ion, crotonate ion, tetrolate ion, cyclopropanecarboxylate ion, valerate ion, isovalerate ion, pivalate cation, angelicate ion, tiglate ion, cyclobutanecarboxylate ion, hexanoate ion, cyclopentanecarboxylate ion, heptanoate ion, sorbate ion, cyclohexanecarboxylate ion, benzoate ion, octanoate ion, 2-ethylhexanoate ion, toluate ion, 2-norbornanecarboxylate ion, nonanoate ion, cinnamate ion, decanoate ion, adamantanecarboxylate ion, geranate ion, undecylenate ion, laurate ion, and naphthoate ion. The carboxylate anion is preferably acetate ion, propionate ion, acrylate ion, propargyl ion, butyrate ion, isobutyrate ion, methacrylate ion, crotonate ion, tetrolate ion, valerate ion, isovalerate ion, pivalate ion, methoxyacetate ion, ethoxyacetate ion, propoxyacetate ion, (2-methoxyethoxy)acetate ion, (2-ethoxyethoxy)acetate ion, (2-propoxyethoxy)acetate ion, 3-(2-methoxyethoxy)propionate ion, 3-(2-ethoxyethoxy)propionate ion, 3-(3-methoxypropoxy)propionate ion, 3-(3-ethoxypropoxy)propionate ion, 3-(3-propoxypropoxy)propionate ion, 3-[2-(2-methoxyethoxy)ethoxy]propionate ion, 3-[2-(2-ethoxyethoxy)ethoxy]propionate ion, 4,7,10,13-tetraoxatetradecane ion, 4,7,10,13-tetraoxapentadecane ion, 4,7,10,13,16-pentaoxaheptadecane ion, 4,7,10,13,16-pentaoxaoctadecane ion, (methylthio)acetate ion, (ethylthio)acetate ion, 3-(methylthio)propionate ion, 3-[(2-methoxyethyl)thio]propionate ion, or 3-[(2-ethoxyethyl)thio]propionate ion, particularly preferably acetate ion, methoxyacetate ion, acrylate ion, or methacrylate ion, but the present invention is not limited to these ions.

[0107] The imidazolium carboxylate represented by formula (1) is preferably an onium salt formed by a combination of a cation selected from 1,3-bis(2-methoxyethyl)imidazolium, 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1,3-bis(3-methylthiopropyl)imidazolium, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium, 1-methoxypropyl-3-methylthiopropylimidazolium, 1,3-bis(2-methoxyethyl)-2-methylimidazolium, and 1,3-bis(3-methoxypropyl)-2-methylimidazolium and an anion selected from acetate ion, methoxyacetate ion, acrylate ion, and methacrylate ion.

[0108] More specifically, the onium salts represented by formula (1) include 1,3-bis(2-methoxyethyl)imidazolium acetate, 1,3-bis(3-methoxypropyl)imidazolium acetate, 1,3-bis(3-methoxypropyl)imidazolium acrylate, 1,3-bis(3-methoxypropyl)imidazolium methacrylate, 1,3-bis(3-ethoxypropyl)imidazolium acetate, 1-methoxypropyl-3-methylthiopropylimidazolium acetate, 1,3-bis(3-methylthiopropyl)imidazolium acetate, 1,3-bis(2-methoxyethyl)-2-methylimidazolium acetate, 1,3-bis(2-methoxyethyl)-2-methylimidazolium acrylate, 1,3-bis(2-methoxyethyl)-2-methylimidazolium methacrylate, 1,3-bis(3-methoxypropyl)-2-methylimidazolium acetate, 1,3-bis(3-methoxypropyl)-2-methylimidazolium acrylate, 1,3-bis(3-methoxypropyl)-2-methylimidazolium methacrylate, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium acetate, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium acrylate, and 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium methacrylate. The onium salt is preferably 1,3-bis(3-methoxypropyl)imidazolium acetate, 1,3-bis(3-methoxypropyl)imidazolium acrylate, or 1,3-bis(3-methoxypropyl)imidazolium methacrylate, but the present invention is not limited to these compounds.

[0109] The polysaccharide in the present invention is a substance composed of a large number of monosaccharide molecules polymerized by glycosidic bonds. Examples of the monosaccharide molecules include glucose, fructose, glucosamine, and N-acetylglucosamine. Glucose-derived polysaccharides include glycogen, starch, cellulose, dextrin, and gellan gum, fructose-derived polysaccharides include fructan, and glucose-derived polysaccharides include chitin and chitosan. In particular, insoluble cellulose, gellan gum, chitin, chitosan, etc. are applicable to the present invention.

[0110] Cellulose refers to glucose polymers and their derivatives polymerized through β-1,4-glucosidic bonds. The degree of polymerization of glucose in cellulose is not particularly limited, but is preferably 200 or higher. Examples of derivatives include carboxymethylated derivatives, aldehydated derivatives, and esterified derivatives. Cellulose can also contain cellooligosaccharides and cellobiose, which are partial decomposition products of cellulose. In addition, cellulose can be a composite material with β-glucosides (glycosides), lignocellulose of lignin and / or hemicellulose, or a composite material with pectin, etc. Cellulose can be crystalline cellulose or amorphous cellulose, but is preferably crystalline cellulose. In addition, cellulose can be naturally derived or artificially synthesized. The source of cellulose is also not limited. Cellulose can be of plant, fungal, or bacterial origin.

[0111] The cellulose according to the present invention further includes cellulose-containing materials. Specific examples of the cellulose-containing materials include pulp, natural fibers such as cotton and hemp, regenerated fibers such as rayon, cuprammonium, and acetate, straw and other types of stalks, agricultural wastes such as bagasse and wood chips, and biomass including waste paper, construction waste, and various other wastes. When natural fibers such as pulp, cotton, and hemp, regenerated fibers such as rayon, cuprammonium, and acetate, stalks such as straw, agricultural wastes such as bagasse and wood chips, biomass such as waste paper, and various wastes such as construction waste are dissolved in the onium salt described in the present invention, it is preferable to use slices of these materials to shorten the dissolution time required.

[0112] The "esterifying agent" used in step (2) of the production method of the present invention is explained below.

[0113] The "esterifying agent" used in the present invention is an esterifying agent represented by the following formula (2) or (3).

[0114] Formula (2):

[0115] Formula (3):

[0116] In formula (2) or (3), R 5 is a C1-C 12 hydrocarbyl group and may contain heteroatoms, double bonds, branched structures, and / or cyclic structures.

[0117] In formula (2) or (3), R 5 of the "C1-C 12 hydrocarbyl group" preferably has 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms. The hydrocarbon can be straight-chain and can contain branched and / or cyclic structures and / or double bonds.

[0118] In formula (2) or (3), R 5 of the "C1-C12 Examples of "hydrocarbyl" include linear or branched C1-C 12 alkyl, linear or branched C2-C 12 alkenyl, linear or branched C2-C 12 alkynyl, optionally branched C3-C 12 cycloalkyl, optionally branched C3-C 12 cycloalkenyl, optionally branched C6-C 12 aryl and optionally branched C7-C 12 aralkyl.

[0119] Preferably linear or branched C1-C 12 alkyl, linear or branched C2-C 12 alkenyl and optionally branched C3-C 12 cycloalkyl.

[0120] In formula (2) or (3), R 5 of "linear or branched C1-C 12 alkyl" is preferably linear or branched C1-C8 alkyl, more preferably linear or branched C1-C4 alkyl, and even more preferably linear or branched C1-C3 alkyl.

[0121] In formula (2) or (3), R 5 of "linear or branched C2-C 12 alkenyl" is preferably linear or branched C2-C8 alkenyl, more preferably linear or branched C2-C4 alkenyl, and even more preferably linear or branched C2-C3 alkenyl.

[0122] In formula (2) or (3), R 5 of "optionally branched C3-C 12 cycloalkyl" is preferably optionally branched C3-C8 cycloalkyl, more preferably optionally branched C3-C4 cycloalkyl, and even more preferably C3 cycloalkyl.

[0123] In formula (2) or (3), R 5 of "C1-C 12 hydrocarbyl" specific examples include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, vinyl, ethynyl, propenyl, isopropenyl, allyl, propargyl, butenyl, crotyl, butadienyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, phenyl, benzyl, tolyl, styryl and 2,4,6-trimethylphenyl. Preferably methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl and hexyl, more preferably methyl, ethyl, propyl, isopropyl and tert-butyl.

[0124] The following explains R in formula (2) or (3). 5 This is an embodiment of a hydrocarbon group containing a heteroatom.

[0125] In formula (2) or (3), when R 5 is a "hydrocarbon group containing a heteroatom", the hydrocarbon group can be straight-chain and can contain branches and / or cyclic structures and / or double bonds.

[0126] In formula (2) or (3), when R 5 is a hydrocarbon group containing a heteroatom, the number of carbon atoms is preferably 2 to 12, more preferably 2 to 8, and even more preferably 2 to 4.

[0127] In formula (2) or (3), when R 5 is a hydrocarbon group containing a heteroatom, the number of heteroatoms is preferably 1 to 5, more preferably 1 or 2. Examples of heteroatoms include nitrogen atoms, oxygen atoms, and sulfur atoms.

[0128] In formula (2) or (3), R 5 The "hydrocarbon group containing a heteroatom" of R means that in a hydrocarbon group without heteroatoms, (i) the bond between two adjacent carbon atoms and / or (ii) the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) are replaced by structures such as -O-, -N<, -NH-, -S-, -C(=O)-O-, -C(=O)-, =N-, -C(=O)-N<, -C(=O)-NH-, -O-C(=O)-O-, -O-C(=O)-N<, -O-C(=O)-NH-, -C(=O)-N[-C(=O)-]-, -C(=O)-NH-C(=O)-, >N-C(=O)-N<, >N-C(=O)-NH-, -HN-C(=O)-NH-, -S(=O)-, -S(=O)2-, -S(=O)2-O-, -O-S(=O)2-O-, >N-C(=S)-N<, >N-C(=S)-NH-, -HN-C(=S)-NH-, -C(=N-)- or -C(=NH)- to form a hydrocarbon group. The number and combination of these structural substitutions are not particularly limited.

[0129] Preferably, the heteroatom-containing hydrocarbon group is a hydrocarbon group formed by replacing (i) the bond between two adjacent carbon atoms and / or (ii) the hydrogen atoms of one -CH2- (methylene) and the hydrogen atoms of another -CH2- (methylene) in the hydrocarbon group with -O- or -S-, and more preferably -O-.

[0130] R in formula (2) or formula (3) 5In (i), the bond between two adjacent carbon atoms and / or (ii) the hydrogen atoms of one -CH2- (methylene) and another -CH2- (methylene) in the hydrocarbon group are replaced by -O- or -S-. The structure can not only be an -O- structure (ether structure) or an -S- structure (thioether structure), but also an epoxy structure or a thioepoxy structure, such as an epoxy group, a thioepoxy group, a glycidyl ether group or a cyclohexyl epoxy group.

[0131] In formula (2) or formula (3), when R 5 When containing two or more -O- and / or -S- structures, the number of carbon atoms between the -O- and / or -S- structures is preferably two or more.

[0132] In formula (2) or (3), R 5 Examples of the "heteroatom-containing hydrocarbon group" include a straight-chain or branched-chain alkyl group containing a heteroatom, a straight-chain or branched-chain alkenyl group containing a heteroatom, a straight-chain or branched-chain alkynyl group containing a heteroatom, an optionally branched cycloalkyl group containing a heteroatom, an optionally branched cycloalkenyl group containing a heteroatom, an optionally branched aryl group containing a heteroatom, and an optionally branched aralkyl group containing a heteroatom.

[0133] Preferred are a straight-chain or branched-chain alkyl group containing a heteroatom, a straight-chain or branched-chain alkenyl group containing a heteroatom, and an optionally branched cycloalkyl group containing a heteroatom.

[0134] The "straight-chain or branched-chain alkyl group containing a heteroatom" is preferably a straight-chain or branched-chain C1-C alkyl group containing 1 to 5 heteroatoms. 12 alkyl group.

[0135] In another embodiment, the straight-chain or branched-chain alkyl group containing a heteroatom is preferably a straight-chain or branched-chain C1-C alkyl group containing 1 or 2 heteroatoms. 12 alkyl group, more preferably a straight-chain or branched-chain C1-C8 alkyl group containing 1 or 2 heteroatoms, and even more preferably a straight-chain or branched-chain C1-C4 alkyl group containing 1 or 2 heteroatoms.

[0136] The "straight-chain or branched-chain alkenyl group containing a heteroatom" is preferably a straight-chain or branched-chain C2-C alkenyl group containing 1 to 5 heteroatoms. 12 alkenyl group.

[0137] In another embodiment, the straight-chain or branched-chain alkenyl group containing a heteroatom is preferably a straight-chain or branched-chain C2-C alkenyl group containing 1 or 2 heteroatoms. 12 alkenyl group, more preferably a straight-chain or branched-chain C2-C8 alkenyl group containing 1 or 2 heteroatoms, and even more preferably a straight-chain or branched-chain C2-C4 alkenyl group containing 1 or 2 heteroatoms.

[0138] The "optionally branched cycloalkyl group containing a heteroatom" is preferably an optionally branched C3-C cycloalkyl group containing 1 to 5 heteroatoms. 12Cycloalkyl group.

[0139] In another embodiment, the optionally branched cycloalkyl group containing a heteroatom is preferably an optionally branched C3-C 12 cycloalkyl group containing 1 or 2 heteroatoms, more preferably an optionally branched C3-C8 cycloalkyl group containing 1 or 2 heteroatoms, and even more preferably an optionally branched C3-C4 cycloalkyl group containing 1 or 2 heteroatoms.

[0140] In formula (2) or (3), R 5 's "hydrocarbyl group containing a heteroatom" is preferably methoxymethyl, methoxyethyl, ethoxymethyl, propoxy or 2-methoxyethoxy, more preferably methoxymethyl, methoxyethyl or 2-methoxyethoxy, but the present invention is not limited to these groups.

[0141] In formula (2) or (3), R 5 is preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, octyl, dodecyl, tert-butyl, dodecyl, allyl, phenyl or methoxymethyl.

[0142] In formula (2) or (3), R 5 is preferably the same as R 4 in formula (1) and formula (1-2).

[0143] In formula (3), R 6 is a hydrogen atom or a methyl group.

[0144] More specific examples of the esterifying agent represented by formula (2) or (3) include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, isovaleric anhydride, pivalic anhydride, hexanoic anhydride, heptanoic anhydride, octanoic anhydride, nonanoic anhydride, decanoic anhydride, lauric anhydride, cyclohexanoic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, allylic anhydride, crotonic anhydride, methacrylic anhydride, methoxyacetic anhydride, phenoxyacetic anhydride, 4-methoxybenzoic anhydride, isopropenyl acetate, vinyl acetate, vinyl propionate, vinyl crotonate, butyl vinyl ester and pivalic vinyl ester. Preferred are acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, isovaleric anhydride, pivalic anhydride, hexanoic anhydride, heptanoic anhydride, octanoic anhydride, benzoic anhydride, allylic anhydride, methoxyacetic anhydride, isopropenyl acetate, vinyl acetate, vinyl propionate and butyl vinyl ester. More preferred are acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, isovaleric anhydride, pivalic anhydride, benzoic anhydride, isopropenyl acetate, vinyl acetate and butyl vinyl ester.

[0145] The solvent in which the esterified polysaccharide is insoluble used in step (3) of the production method of the present invention is explained below.

[0146] The "esterified polysaccharide-insoluble solvent" used in step (3) is at least one solvent selected from water, alcohols, and ketones. Specific examples of the alcohol include methanol, ethanol, propanol, and butanol. Specific examples of the ketone include acetone and methyl ethyl ketone. These solvents can be used in combination.

[0147] The carboxylic acid represented by the following formula (4) contained in the filtrate separated in step (4) of the present invention will be explained below.

[0148] Formula (4):

[0149] In formula (4), R 5 is a C1-C 12 hydrocarbon group and may contain a heteroatom, a double bond, a branched structure, and / or a cyclic structure. R 5 is the same as R 5 in formula (2) or formula (3).

[0150] Specific examples of the carboxylic acid represented by formula (4) include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, cyclohexanoic acid, benzoic acid, 2-methylbenzoic acid, allylic acid, crotonic acid, methacrylic acid, methoxyacetic acid, phenoxyacetic acid, and 4-methoxybenzoic acid. Preferred are acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, hexanoic acid, heptanoic acid, octanoic acid, benzoic acid, allylic acid, and methoxyacetic acid. More preferred are acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, and benzoic acid.

[0151] The amine represented by the following formula (5) used in step (6) of the production method of the present invention will be explained below.

[0152] Formula (5):

[0153] In formula (5), R 7 , R 8 , and R 9 may be the same or different and each represents a hydrogen atom or a C1-C 18 hydrocarbon group, and may contain a double bond, a branched structure, and / or a cyclic structure. The total number of carbon atoms in R 7 , R 8 , and R 9 is 8 or more.

[0154] In R 7 , R 8 , and R 9 in formula (5), the number of carbon atoms in the hydrocarbon group is 1 to 18, preferably 1 to 12, and more preferably 1 to 8.

[0155] R 7 、R 8 and R 9 The total number of carbon atoms in is 8 or greater, preferably 12 or greater and 24 or less.

[0156] Specific examples of the hydrocarbon group represented by R 7 、R 8 and R 9 include: methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, octadecyl. Isopropyl, sec-butyl, isobutyl, tert-butyl, neopentyl, 2-ethylhexyl each have a branched structure.

[0157] Specific examples of the hydrocarbon group containing a double bond represented by R 7 、R 8 and R 9 include: vinyl, ethynyl, propenyl, isopropenyl, allyl, propargyl, butenyl, crotyl, butadienyl and oleyl.

[0158] Specific examples of the hydrocarbon group having a cyclic structure represented by R 7 、R 8 、or R 9 include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, phenyl, benzyl, tolyl, styryl and 2,4,6-trimethylphenyl. Cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl and adamantyl each have a branched structure.

[0159] R 7 、R 8 、and R 9 are preferably a hydrogen atom, methyl, oleyl, 2-ethylhexyl, cyclohexyl, octadecyl or octyl.

[0160] Specific examples of the amine represented by formula (5) include tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trimethylamine, tridecylamine, oleylamine, di-2-ethylhexylamine, dicyclohexylamine, methyloctadecylamine, dimethyloctadecylamine and trioctylamine.

[0161] The steps (1) to (8) of the production method of the present invention will be explained below.

[0162] Step (1) is a step of mixing the onium salt represented by formula (1) with the polysaccharide to dissolve the polysaccharide in the onium salt.

[0163] In step (1), based on the total weight of the mixture of the onium salt and the polysaccharide as 100 wt%, the concentration of the polysaccharide contained in the mixture of the onium salt and the polysaccharide is 5 to 40 wt%, preferably 10 to 25 wt%.

[0164] The temperature at which the polysaccharide is dissolved in the onium salt is 10 to 120 °C, preferably 20 to 100 °C, more preferably 25 to 80 °C.

[0165] In step (1), the mixture of the onium salt and the polysaccharide can be stirred, shaken, ultrasonically irradiated, etc. to promote the dissolution of the polysaccharide.

[0166] Step (2) is a step of adding an esterifying agent represented by formula (2) or formula (3) to the mixture obtained in step (1) to produce an esterified polysaccharide.

[0167] The amount of the esterifying agent added to the mixture obtained in step (1) is 0.1 to 10 equivalents, preferably 1 to 3 equivalents, per glucose unit of the polysaccharide.

[0168] The temperature at which the esterifying agent is added to the mixture obtained in step (1) is -10 to 100 °C, preferably 0 to 80 °C.

[0169] The reaction between the polysaccharide and the esterifying agent is usually carried out with stirring at -10 to 100 °C, preferably 0 to 80 °C, for 0.5 to 2 hours.

[0170] The degree of esterification of the esterified polysaccharide to be produced is not particularly limited, and is preferably 1 to 3.

[0171] Step (3) is a step of adding a solvent insoluble in the esterified polysaccharide to the mixture obtained in step (2) to precipitate the esterified polysaccharide.

[0172] Based on the total weight of the onium salt used in step (1), the amount of the solvent insoluble in the esterified polysaccharide is 1 to 100 times, preferably 5 to 50 times. The temperature during precipitation is not particularly limited, and is preferably 10 to 50 °C; Step (4) is a step of filtering the esterified polysaccharide precipitated in step (3) to separate the esterified polysaccharide from the filtrate containing the onium salt represented by formula (1), the carboxylic acid represented by formula (4), and the solvent insoluble in the esterified polysaccharide.

[0173] The filtration method in step (4) is not particularly limited. Filtration can be carried out under normal pressure or reduced pressure, and can be carried out under heating.

[0174] The filtrate separated in step (4) may contain acetone or acetaldehyde, i.e., the decomposition products of the esterifying agent represented by formula (2) or formula (3).

[0175] Step (5) is a step of heating and / or reducing the pressure of the filtrate separated in step (4) to remove the solvent in which the esterified polysaccharide is insoluble from the filtrate.

[0176] The method for removing the solvent in which the esterified polysaccharide is insoluble from the filtrate separated in step (4) by heating and / or reducing the pressure is not particularly limited.

[0177] When removing the solvent in which the esterified polysaccharide is insoluble by heating and / or reducing the pressure, acetone or acetaldehyde, i.e., the decomposition product of the esterifying agent represented by formula (2) or formula (3), can be removed simultaneously.

[0178] Step (6) is a step of adding the amine represented by formula (5) to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) obtained in step (5) to produce an amine-carboxylate salt, and separating the onium salt-containing layer from the amine-carboxylate salt-containing layer.

[0179] The amount of the amine added to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) is 1 equivalent or more per equivalent of the carboxylic acid, usually 1 to 1.5 equivalents, preferably 1 to 1.2 equivalents, and more preferably 1 to 1.1 equivalents. An amine-carboxylate salt composed of the added amine and the carboxylic acid of formula (4) is generated, and a mixture of the onium salt of formula (1), the amine-carboxylate salt, and the remaining amine is obtained.

[0180] The reaction conditions for generating the amine-carboxylate salt by adding the amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) are as follows: the temperature is 0°C to 100°C, preferably 25°C to 80°C; for the reaction time, after adding the amine, it is preferably stirred for 0.5 to 3 hours, more preferably 1 to 2 hours.

[0181] Step (7) is a step of recovering the onium salt-containing layer separated in step (6) as a recovered liquid containing the onium salt.

[0182] In step (7), the onium salt-containing layer separated in step (6) is recovered. The recovery method can be liquid separation or the like.

[0183] In step (7), a recovered liquid containing the onium salt represented by formula (1) is obtained. The residual amine that may be contained in the obtained recovered liquid can be removed by heating and / or reducing the pressure of the obtained recovered liquid.

[0184] Step (8) is a step of introducing the recovered liquid recovered in step (7) into step (1) and recycling the recovered liquid containing the onium salt represented by formula (1) as the onium salt used in step (1).

[0185] Step (8) is a step of introducing the onium salt-containing recovered liquid obtained in step (7) into step (1), and the method of this step is not particularly limited.

[0186] In a preferred embodiment of the present invention, in step (6) of the above method for preparing an esterified polysaccharide, water and / or a hydrophilic solvent is added to the mixture obtained in step (5) containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4).

[0187] A hydrophilic solvent refers to a solvent that can be dissolved in water or is miscible with water. Specific examples include C1-C4 lower alcohols, such as methanol, ethanol, propanol, and ethylene glycol.

[0188] Based on the total amount of the mixture containing the onium salt represented by formula (1), the carboxylic acid represented by formula (4), and water and / or a hydrophilic solvent being 100 wt%, the content of water and / or a hydrophilic solvent is 0.1 wt% to 90 wt% or 1 wt% to 70 wt%, preferably 5 wt% to 50 wt%.

[0189] In a preferred embodiment of the present invention, in step (6) of the above method for preparing an esterified polysaccharide, (i) the amine represented by formula (5) or (ii) an amine solution in which the amine is diluted with a hydrophobic solvent is added to the mixture obtained in step (5) containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4).

[0190] In the above (ii) where an amine solution in which the amine is diluted with a hydrophobic solvent is added, examples of the solvent used include chloroform, dichloromethane, 2-ethylhexanol, cyclohexanol, 1-octanol, and ethyl acetate, among which chloroform, 2-ethylhexanol, cyclohexanol, and 1-octanol are preferred.

[0191] The concentration of the amine solution obtained by diluting with a hydrophobic solvent is generally 0.01 g / L to 10.0 g / L, preferably 0.1 g / L to 5.00 g / L.

[0192] In a preferred embodiment of the present invention, water and a hydrophobic solvent can be further added to the mixture obtained in step (5) used in step (6) containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4).

[0193] The hydrophobic solvent can be the solvent used to dilute the amine to be added. Alternatively, the hydrophobic solvent can be added alone to the mixture in step (6) without being used to dilute the amine. The hydrophobic solvent added to the mixture obtained in step (5) is preferably a solvent that undergoes phase separation with water. Examples of the solvent that undergoes phase separation with water include hexane, heptane, toluene, chloroform, dichloromethane, 2-ethylhexanol, cyclohexanol, 1-octanol, and ethyl acetate. The solvent is preferably chloroform, 2-ethylhexanol, cyclohexanol, or 1-octanol.

[0194] When the mixture obtained in step (5) used in step (6) contains water and a hydrophobic solvent, the added amine forms an amine-carboxylate and is mainly extracted into the hydrophobic solvent layer. On the other hand, the onium salt represented by formula (1) is present in the aqueous layer. Therefore, separating the solvent layers enables the separation of the amine-carboxylate, resulting in an aqueous layer containing the onium salt represented by formula (1), with the amount of the carboxylic acid represented by formula (4) reduced or almost completely removed. It is difficult to remove the carboxylic acid represented by formula (4) present together with the onium salt of formula (1) by evaporation. However, the water in the aqueous layer containing the onium salt of formula (1) can be easily removed by evaporation to obtain the onium salt of formula (1).

[0195] Due to the presence of the carboxylic acid represented by formula (4), the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) exhibits a significantly reduced cellulose solubility. However, performing step (6) of the production method of the present invention significantly increases the cellulose solubility. For example, by removing 50% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 100% of the carboxylic acid represented by formula (4) from the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4), the cellulose solubility can be greatly increased.

[0196] When the amine is added in the form of an amine solution in which the amine is diluted with a solvent, and the separated liquid containing the onium salt represented by formula (1) separated in step (6) contains a solvent, the solvent can be distilled off from the separated liquid by heating and / or reducing the pressure.

[0197] In a preferred embodiment of the present invention, in step (1) of the method for preparing an esterified polysaccharide, the onium salt represented by formula (1) has at least two types.

[0198] Specific examples of the onium salt represented as a mixture of at least two types by formula (1) include a mixture of 1,3-dimethylimidazolium acetate and 1,3-diethylimidazolium acetate, a mixture of 1,3-dimethylimidazolium acetate and 1-ethyl-3-methylimidazolium acetate, a mixture of 1,3-diethylimidazolium acetate and 1-ethyl-3-methylimidazolium acetate, and a mixture of 1,3-dimethylimidazolium acetate, 1,3-diethylimidazolium acetate, and 1-ethyl-3-methylimidazolium acetate.

[0199] In a preferred embodiment of the present invention, in step (2) of the method for preparing an esterified polysaccharide, the esterifying agent represented by formula (2) or formula (3) has at least two types.

[0200] Specific examples of the esterifying agent represented by formula (2) or formula (3) as a mixture of at least two types include a mixture of acetic anhydride and propionic anhydride, a mixture of acetic anhydride and butyric anhydride, and a mixture of isopropenyl acetate and vinyl butyrate.

[0201] In a preferred embodiment of the present invention, in step (1) of the above method for preparing an esterified polysaccharide, the onium salt represented by formula (1) is in the form of an onium salt solution, wherein the onium salt is diluted with an aprotic polar solvent.

[0202] Examples of the aprotic polar solvent include but are not limited to dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, acetonitrile, and pyridine. The aprotic polar solvent may contain two or more organic solvents. These organic solvents are difficult to dissolve polysaccharides alone; however, when the solvent is used in combination with the onium salt (1) or with an onium salt composition, the solvent can contribute to, for example, increasing the solubility of the polysaccharide, accelerating the polysaccharide dissolution rate by reducing the viscosity, improving the processability during the polysaccharide recovery process, and controlling the physical properties of the recovered polysaccharide.

[0203] In a preferred embodiment of the present invention, in step (7) of the above method for preparing an esterified polysaccharide, an amine represented by formula (5) is added to the recovered liquid containing the onium salt to produce an amine-carboxylate, the onium salt-containing layer is separated from the amine-carboxylate-containing layer, and the separated onium salt-containing layer is recovered as the onium salt-containing recovered liquid.

[0204] The application of the esterified polysaccharide product obtained according to the present invention is not particularly limited. For example, the esterified polysaccharide product obtained according to the present invention can be used in the textile field, such as fibers, ropes, nets, woven or knitted fabrics, felts, wools, wood plastics, carbon fiber composites, glass fiber composites, cellulose nanofiber composites, lignocellulose nanofiber composites, and other textile composites; in the film field, such as polarizing plate protective films and optical films; in the plastic field, such as for medical devices, electronic component materials, packaging materials, spectacle frames, tubes, rods, tools, tableware, and toys; and in the civil engineering field, such as for concrete viscosity regulators and clay mineral viscosity regulators.

[0205] Examples The present invention will be described in detail below with reference to examples. However, the present invention is not limited by these examples.

[0206] 1,3-bis(3-methoxypropyl)imidazolium acetate ([(MeOPr)2Im][AcO]) used in the examples was prepared as described in Preparation Example 1 below.

[0207] Preparation Example 1 Charge a 5 L three-necked reactor purged with nitrogen with 260 g (3.22 mol based on formaldehyde) of 37 wt% aqueous formaldehyde solution (produced by Tokyo Chemical Industry Co., Ltd.), 290 g (4.83 mol) of acetic acid (produced by Junsei Chemical Co., Ltd.), 573 g (6.43 mol) of 3-methoxypropylamine (produced by Tokyo Chemical Industry Co., Ltd.), and 461 g (3.22 mol based on glyoxal) of 40 wt% aqueous glyoxal solution (produced by Tokyo Chemical Industry Co., Ltd.). Heat the resulting mixture to 40 °C and stir for 3 hours to obtain a yellow transparent liquid.

[0208] The 1H NMR data results of the resulting yellow transparent liquid are shown below.

[0209] 1H NMR (DMSO-d6) δ (ppm) = 9.41 (s, 1H), 7.78 (d, 2H), 4.22 (t, 4H), 3.33 (t, 4H), 3.22 (s, 6H), 2.07 - 2.00 (m, 4H), 1.56 (s, 3H) The results of the 1H NMR data indicate that the obtained yellow transparent liquid is 1,3-bis(3-methoxypropyl)imidazolium acetate ([(MeOPr)2Im][AcO]).

[0210] The amount of the obtained 1,3-bis(3-methoxypropyl)imidazolium acetate ([(MeOPr)2Im][AcO]) is 811 g, and the yield is 93%.

[0211] The 1-ethyl-3-methylimidazolium acetate used in Example 2 was produced by Tokyo Chemical Industry Co., Ltd.

[0212] Example 1 Place 1,3-bis(3-methoxypropyl)imidazolium acetate (9.20 g) and cellulose (1.02 g) (Avicel (registered trademark) PH-101) in a vial and stir at 80 °C for 1 hour. After one hour, observe the state of the resulting product and confirm that the cellulose has completely dissolved.

[0213] While cooling the reaction solution in an ice bath, add acetic anhydride (6.75 g, 3 equivalents per glucose unit) (produced by FUJIFILM Wako Pure Chemical Corporation). After addition, return the mixture to room temperature (25 °C) and stir for 2 hours.

[0214] After the reaction, pour the reaction solution into methanol (100 mL) to precipitate the solid. Filter the precipitated solid, wash it, and then dry it under vacuum to obtain a white solid.

[0215] The IR data of the obtained white solid are as follows. The wavelengths of C=O stretching vibration, C-H symmetric bending vibration, and C-O stretching vibration were confirmed by FT-IR (manufactured by Jasco Corporation): IR 1738 cm -1 (C=O stretching vibration), 1365 cm -1 (C-H symmetric bending vibration), 1211 cm -1 (C-O stretching vibration).

[0216] Based on the results of the IR data, it was confirmed that the obtained white solid was acetylated cellulose.

[0217] Furthermore, the remaining hydroxyl groups in glucose, which is a molecule constituting the obtained acetyl cellulose, were modified with a large excess of benzoyl chloride (manufactured by Fujifilm Wako Pure Chemical Corporation), and the degree of acetylation was measured by 1H NMR analysis. The measurement results are as follows.

[0218] Degree of acetylation: 2.90 Acetic acid was removed from the filtrate containing 1,3-bis(3-methoxypropyl)imidazolium acetate and acetic acid in the following manner.

[0219] The filtrate was concentrated to remove methanol. To the concentrated filtrate (2.00 g), ion-exchanged water (6.04 g), 2-ethylhexanol (4.00 g) (manufactured by Junsei Chemical Co., Ltd.), and oleylamine (2.98 g) (manufactured by Sigma) were added and stirred.

[0220] The mixture was separated into an aqueous layer containing 1,3-bis(3-methoxypropyl)imidazolium acetate and an organic layer containing oleylamine acetate and 2-ethylhexanol. The obtained aqueous layer was concentrated and dried, and then 1H NMR was measured to determine the acetic acid removal rate according to the following formula.

[0221] Acetic acid removal rate (%) = (1 - (integral value of CH3 after removal - 3.00) / (integral value of CH3 before removal - 3.00)) × 100 Acetic acid removal rate (%) = 98.05 1,3-Bis(3-methoxypropyl)imidazolium acetate (0.91 g) from which acetic acid had been removed and cellulose (0.10 g) were placed in a vial and stirred at 80 °C for 1 hour.

[0222] After one hour, the state of the obtained product was observed, and it was confirmed that the cellulose had completely dissolved.

[0223] While cooling the reaction solution in an ice bath, acetic anhydride (0.68 g, 3 equivalents per glucose unit) (manufactured by Fujifilm Wako Pure Chemical Corporation) was added. After the addition, the mixture was returned to room temperature (25 °C) and stirred for 2 hours.

[0224] After the reaction, the reaction solution was poured into methanol (50 mL) to precipitate the solid. The precipitated solid was filtered, washed, and then dried under vacuum to obtain a white solid.

[0225] The IR data of the obtained white solid are shown below. The wavelengths of C=O stretching vibration, C-H symmetric bending vibration, and C-O stretching vibration were confirmed by FT-IR (manufactured by Jasco Corporation): IR 1738 cm -1 (C=O stretching vibration), 1365 cm -1 (C-H symmetric bending vibration), 1211 cm -1 (C-O stretching vibration).

[0226] Based on the results of the IR data, it was confirmed that the obtained white solid was acetylated cellulose.

[0227] In addition, the remaining hydroxyl groups in glucose, which is a molecule constituting the obtained acetylated cellulose, were modified with a large excess of benzoyl chloride (manufactured by FUJIFILM Wako Pure Chemical Corporation), and the degree of acetylation was measured by 1H NMR analysis. The measurement results are shown below.

[0228] Degree of acetylation: 2.92 Comparative Example 1 Cellulose (0.10 g) (Avicel (registered trademark) PH-101) was added to the filtrate (0.99 g) obtained in Example 1, and the mixture was stirred at 100 °C for 3 hours. After 3 hours, the state of the obtained product was observed, and it was confirmed that the cellulose was not dissolved at all.

[0229] Example 2: 1-Ethyl-3-methylimidazolium acetate (1.80 g) and cellulose (0.20 g) (Avicel (registered trademark) PH-101) were placed in a vial and stirred at 80 °C for 1 hour. After 1 hour, the state of the obtained product was observed, and it was confirmed that the cellulose had completely dissolved.

[0230] While cooling the reaction solution in an ice bath, acetic anhydride (1.37 g, 3 equivalents per glucose unit) (manufactured by FUJIFILM Wako Pure Chemical Corporation) was added. After the addition, the mixture was returned to room temperature (25 °C) and stirred for 2 hours.

[0231] After the reaction, the reaction solution was poured into methanol (50 mL) to precipitate the solid. The precipitated solid was filtered, washed, and then dried under vacuum to obtain a light yellow solid.

[0232] The IR data of the obtained white solid are shown below. The wavelengths of C=O stretching vibration, C-H symmetric bending vibration, and C-O stretching vibration were confirmed by FT-IR (manufactured by Jasco Corporation): IR 1738 cm-1 (C=O stretching vibration), 1365 cm -1 (C-H symmetric bending vibration), 1211 cm -1 (C-O stretching vibration).

[0233] Based on the results of the IR data, it was confirmed that the obtained white solid was acetylated cellulose.

[0234] In addition, the remaining hydroxyl groups in glucose, which is a molecule constituting the obtained acetylated cellulose, were modified with a large excess of benzoyl chloride (produced by FUJIFILM Wako Pure Chemical Corporation), and the degree of acetylation was measured by 1H NMR analysis. The measurement results are shown below.

[0235] Degree of acetylation: 2.77 In the following manner, acetic acid was removed from the filtrate containing 1-ethyl-3-methylimidazolium acetate and acetic acid: The filtrate was concentrated to remove methanol. To the concentrated filtrate (2.82 g), ion-exchanged water (5.43 g), 2-ethylhexanol (3.61 g) (produced by Junsei Chemical Co., Ltd.) and di-2-ethylhexylamine (3.81 g) (produced by Koei Chemical Co., Ltd.) were added and stirred.

[0236] The mixture was separated into an aqueous layer containing 1-ethyl-3-methylimidazolium acetate and acetic acid and an organic layer containing di-2-ethylhexylamine acetate and 2-ethylhexanol. The obtained aqueous layer was concentrated and dried, and then 1H NMR was measured to determine the acetic acid removal rate according to the following formula.

[0237] Acetic acid removal rate (%) = (1 - (integral value of CH3 after removal - 3.00) / (integral value of CH3 before removal - 3.00)) × 100 Acetic acid removal rate (%) = 96.17 1-ethyl-3-methylimidazolium acetate (0.91 g) from which acetic acid had been removed and cellulose (0.11 g) were placed in a vial and stirred at 80 °C for 1 hour.

[0238] After one hour, the state of the obtained product was observed, and it was confirmed that the cellulose had completely dissolved.

[0239] While cooling the reaction solution in an ice bath, acetic anhydride (0.67 g, 3 equivalents per glucose unit) was added. After addition, the mixture was returned to room temperature (25 °C) and stirred for 2 hours.

[0240] After the reaction, the reaction solution was poured into methanol (100 mL) to precipitate the solid. The precipitated solid was filtered, washed, and then dried under vacuum to obtain a white solid.

[0241] The IR data of the obtained white solid are shown below. The wavelengths of C=O stretching vibration, C-H symmetric bending vibration, and C-O stretching vibration were confirmed by FT-IR (manufactured by Jasco Corporation): IR 1738 cm -1 (C=O stretching vibration), 1365 cm -1 (C-H symmetric bending vibration), 1211 cm -1 (C-O stretching vibration).

[0242] Based on the results of the IR data, it was confirmed that the obtained white solid was acetylated cellulose.

[0243] Furthermore, the remaining hydroxyl groups in glucose, which is a molecule constituting the obtained acetylated cellulose, were modified with a large excess of benzoyl chloride, and the degree of acetylation was measured by 1H NMR analysis. The measurement results are shown below.

[0244] Degree of acetylation: 2.97 Industrial Applicability According to the present invention, a method for producing an esterified polysaccharide can be provided, which can further remove or reduce carboxylic acid substantially without using a catalyst for esterifying cellulose, and the recovered liquid containing an onium salt recovered by this production method can be recycled.

Claims

1. A method for preparing an esterified polysaccharide, comprising the following steps (1) to (8): Step (1): mixing an onium salt represented by formula (1) with a polysaccharide to dissolve the polysaccharide in the onium salt: Formula (1): ； in R 1 and R 2 are the same or different and each represents a hydrocarbon group optionally containing heteroatoms, R 1 and R 2 Contains branched chains and / or cyclic structures and / or double bonds, R 3 represents a hydrogen atom or a C1-C5 hydrocarbon group, and R 4 Represents C1-C 12 Hydrocarbyl and containing heteroatoms, double bonds, branched structures and / or cyclic structures; Step (2): adding an esterifying agent represented by formula (2) or formula (3) to the mixture obtained in step (1) to produce an esterified polysaccharide: Formula (2): ； in R 5 Represents C1-C 12 The hydrocarbon group may contain heteroatoms, double bonds, branched structures and / or cyclic structures. Formula (3): ； in R 5 Represents C1-C 12 The hydrocarbon group may contain heteroatoms, double bonds, branched structures and / or cyclic structures, and R 6 represents a hydrogen atom or a methyl group; Step (3): adding at least one solvent selected from water, alcohol and ketone to the mixture obtained in step (2) to precipitate the esterified polysaccharide, wherein the esterified polysaccharide is insoluble in the solvent; Step (4): filtering the esterified polysaccharide precipitated in step (3) to separate the esterified polysaccharide from a filtrate containing the onium salt represented by formula (1), the carboxylic acid represented by formula (4), and the solvent in which the esterified polysaccharide is insoluble: Formula (4): ； in R 5 Represents C1-C 12 The hydrocarbon group may contain heteroatoms, double bonds, branched structures and / or cyclic structures; Step (5): heating and / or reducing the pressure of the filtrate separated in step (4) to remove the solvent in which the esterified polysaccharide is insoluble from the filtrate; Step (6): adding an amine represented by formula (5) to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) obtained in step (5) to produce an amine-carboxylate, and separating the onium salt-containing layer from the amine-carboxylate-containing layer: Formula (5): ； in R 7 , R 8 and R 9 are the same or different and each represents a hydrogen atom or a C1-C 18 A hydrocarbon group, and containing double bonds, branched structures and / or cyclic structures, and R 7 , R 8 and R 9 The total number of carbon atoms in the compound is 8 or greater; Step (7): recovering the onium salt-containing layer separated in step (6) as an onium salt-containing recovery liquid; and Step (8): introducing the recovered liquid recovered in step (7) into step (1).

2. The method for preparing esterified polysaccharides according to claim 1, In step (6), water and / or a hydrophilic solvent is added to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (4) obtained in step (5).

3. The method for preparing esterified polysaccharides according to claim 1, In step (6), The following is added to the mixture containing the onium salt represented by the formula (1) and the carboxylic acid represented by the formula (4) obtained in step (5): (i) an amine represented by formula (5), or (ii) diluting the amine solution of the amine with a hydrophobic solvent.

4. The method for preparing esterified polysaccharides according to claim 1, in, In step (1), the onium salt represented by formula (1) is of at least two types.

5. The method for preparing esterified polysaccharide according to claim 1, in, In step (2), the esterification agent represented by formula (2) or formula (3) is of at least two types.

6. The method for preparing esterified polysaccharides according to claim 1, in, In step (1), the onium salt represented by formula (1) is in the form of an onium salt solution, wherein the onium salt is diluted with an aprotic polar solvent.

7. The method for preparing esterified polysaccharides according to claim 1, in, In step (7), an amine represented by formula (5) is added to the onium salt-containing recovery liquid to produce amine-carboxylate, the onium salt-containing layer is separated from the amine-carboxylate-containing layer, and the separated onium salt-containing layer is recovered as the onium salt-containing recovery liquid.

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