Cellulose derivatives, resin compositions, molded articles, and methods for producing the same.

Abstract

This provides a novel cellulose derivative. [Solution] A cellulose derivative in which at least some of the hydrogen atoms of the hydroxyl groups contained in cellulose are substituted with lower acyl groups and lower alkoxycarbonyl groups, the degree of substitution DS1 of the lower acyl group is between 1.0 and 2.9, and the degree of substitution DS2 of the lower alkoxycarbonyl group is between 0.1 and 2.0.

Description

[Technical Field]

[0001] This disclosure relates to cellulose derivatives, resin compositions, molded articles, and methods for producing the same. [Background technology]

[0002] In recent years, with growing concern for the global environment, there has been a demand for the development of biomass-derived materials to replace petroleum-derived materials. From this perspective, cellulose, the main component of wood and cotton, has attracted attention, and various cellulose derivatives are being studied (Patent Documents 1-3).

[0003] Regarding methods for derivatizing cellulose, attempts have been made to use CO2 as a raw material, taking into consideration the problem of global warming (Non-patent documents 1-3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-279501 [Patent Document 2] Japanese Patent Publication No. 2010-84028 [Patent Document 3] Japanese Patent Publication No. 2010-37385 [Non-patent literature]

[0005] [Non-Patent Document 1] Kelechukwu N. Onwukamike et al., “Detailed Understanding of the DBU / CO2 Switchable Solvent System for Cellulose Solubilization and Derivatization”, ACS Sustainable Chem. Eng. 2018, 6, 1496?1503 [Non-Patent Document 2] Chen-Gang Wang et al., "Carbon Dioxide Mediated Cellulose Dissolution and Derivatization to Cellulose Carbonates in a Low-pressure System", Carbohydrate Polymer Technologies and Applications 3 (2022) 100186

Non-Patent Document 3

Summary of the Invention

Problem to be Solved by the Invention

[0006] However, from the perspective of expanding applications, there remains a continuing demand for the development of cellulose derivatives having excellent thermoplasticity and mechanical properties.

[0007] In view of the above problems, the present disclosure aims to provide a novel cellulose derivative. The present disclosure also aims to provide a novel method for producing a cellulose derivative using CO2 as a raw material.

Means for Solving the Problem

[0008] In order to solve the above problems, the present inventors conducted intensive studies, and have found that a cellulose derivative having excellent thermoplasticity and mechanical properties can be obtained by introducing a lower acyl group and a lower alkoxycarbonyl group into cellulose each in a specific amount. Although the mechanism is not clear, it is presumed that the introduction of lower acyl groups improves thermoplasticity and provides good moldability, while the lower alkyl groups of the lower alkoxycarbonyl groups introduced at the same time are short chains, contributing to the maintenance of interactions between polymer chains. Together, these factors impart excellent thermoplasticity and mechanical properties to the cellulose derivative.

[0009] The gist of this invention is as follows: [1] At least some of the hydrogen atoms of the hydroxyl groups contained in cellulose are substituted with lower acyl groups and lower alkoxycarbonyl groups, The degree of substitution DS1 of the lower acyl group is 1.0 or more and 2.9 or less. The degree of substitution DS2 of the lower alkoxycarbonyl group is between 0.1 and 2.0. Cellulose derivatives. [2] The cellulose derivative according to [1], wherein the lower acyl group is an acetyl group. [3] The cellulose derivative according to [1] or [2], wherein the lower alkoxycarbonyl group is an ethoxycarbonyl group. [4] The cellulose derivative according to any one of [1] to [3], wherein the degree of substitution DS2 of the lower alkoxycarbonyl group is 0.35 or more and 2.0 or less. [5] The degree of substitution DS1 of the lower acyl group is 2.0 or more and 2.6 or less, A cellulose derivative according to any one of [1] to [4], wherein the degree of substitution DS2 of the lower alkoxycarbonyl group is 0.40 or more and 0.60 or less. [6] A cellulose derivative according to any one of [1] to [5], wherein at least some of the hydrogen atoms of the hydroxyl groups contained in the cellulose are further substituted with lower alkyl groups. [7] The cellulose derivative according to [6], wherein the degree of substitution DS3 of the lower alkyl group is 0.10 or more and 0.30 or less. [8] The cellulose derivative according to [6] or [7], wherein the lower alkyl group is an ethyl group. A resin composition comprising a cellulose derivative as described in any of [9] [1] to [8]. A molded article obtained by molding the resin composition described in

[10] [9].

[11] A method for producing a cellulose derivative according to any one of [1] to [8], comprising adding carbon dioxide gas to a solution containing cellulose in which at least some of the hydrogen atoms of the hydroxyl groups contained in the cellulose are replaced with lower acyl groups, a strong base, and an organic solvent, and then reacting it with a lower alkyl halogenated material. [Effects of the Invention]

[0010] This disclosure provides novel cellulose derivatives along with methods for producing them. The cellulose derivatives of this disclosure exhibit excellent thermoplastic and mechanical properties and can be used in a variety of applications. The methods for producing them of this disclosure use CO2 as a raw material and contribute to the reduction of CO2 in the atmosphere. [Brief explanation of the drawing]

[0011] [Figure 1] This is the FT-IR chart for the cellulose derivative of Example 1. [Figure 2] This is the FT-IR chart for the cellulose derivative of Example 2. [Figure 3] This is the FT-IR chart for the cellulose derivative of Example 3. [Figure 4] This is the FT-IR chart for the cellulose derivative of Example 4. [Figure 5] This is the FT-IR chart for the cellulose derivative of Example 5. [Figure 6] This is the FT-IR chart for the cellulose derivative of Example 6. [Figure 7] This is a chart of the 1H-NMR spectrum of the cellulose derivative of Example 2. [Figure 8] This is a chart of the 1H-NMR spectrum of the cellulose derivative of Example 3. [Figure 9] This is a chart of the 1H-NMR spectrum of the cellulose derivative in Comparative Example 2. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure are described below. The configurations and combinations thereof in each embodiment of this disclosure are examples, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of this disclosure. This disclosure is not limited to the embodiments.

[0013] Each aspect disclosed herein can be combined with any other features disclosed herein.

[0014] [Explanation of terms]

[0015] In this specification, "cellulose" refers to a polymer compound in which numerous glucose units (glucopyranose units) are polymerized by β-1,4-glucosidic bonds, wherein the hydroxyl groups bonded to the carbon atoms at positions 2, 3, and 6 of the glucose units are unsubstituted.

[0016] In this specification, "lower alkyl group" refers to an alkyl group having 1 to 6 carbon atoms. Lower alkyl groups may be linear or branched. Examples of lower alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, pentyl group, and hexyl group.

[0017] In this specification, "lower acyl group" refers to -C(=O)-R 1 It is a group represented by R 1 This refers to a lower alkyl group. The above definition and examples apply to lower alkyl groups.

[0018] In this specification, "lower alkoxy group" means -OR 2 It is a group represented by R 2 This refers to a lower alkyl group. The above definition and examples apply to lower alkyl groups.

[0019] In this specification, "degree of substitution" refers to the average number of substituents introduced to the three hydroxyl groups in a glucose unit of a cellulose derivative, per glucose unit.

[0020] [Cellulose derivatives] The cellulose derivatives of this disclosure are cellulose derivatives in which at least some of the hydrogen atoms of the hydroxyl groups contained in cellulose are substituted with lower acyl groups and lower alkoxycarbonyl groups, the degree of substitution DS1 of the lower acyl group is 1.0 or more and 2.9 or less, and the degree of substitution DS2 of the lower alkoxycarbonyl group is 0.1 or more and 2.0 or less.

[0021] Specifically, the cellulose derivatives of this disclosure are conjugates of glucose units represented by the following formula, wherein a lower acyl group and a lower alkoxycarbonyl group are bonded to at least a portion of the bonds extending from the three oxygen atoms of the glucose unit within the conjugate. [ka] (In the formula, * represents a coupling.)

[0022] The lower acyl group and the lower alkoxycarbonyl group may substitute for some of the hydrogen atoms of any of the hydroxyl groups bonded to the carbon atoms at positions 2, 3, and 6 in the glucose unit.

[0023] The lower acyl group is preferably an acetyl group, propionyl group, butyryl group, hexanoyl group, etc., from the viewpoint of imparting thermoplasticity to the cellulose derivative, with the acetyl group being particularly preferred. The lower acyl group may be used alone or in combination of two or more types.

[0024] The lower alkoxycarbonyl group is preferably an ethoxycarbonyl group or a methoxycarbonyl group, with the ethoxycarbonyl group being preferred, from the viewpoint of maintaining the interaction between polymer chains. The lower alkoxycarbonyl group may be used alone or in combination of two or more types.

[0025] In the cellulose derivatives of this disclosure, the degree of substitution DS1 of the lower acyl group is 1.0 or more and 2.9 or less. If the degree of substitution DS1 is within this range, the cellulose derivative can be imparted with excellent thermoplasticity. The degree of substitution DS1 of the lower acyl group is preferably 1.5 or more, more preferably 2.0 or more, from the viewpoint of promoting the reaction by improving solubility in organic solvents during the reaction, and is preferably 2.8 or less, more preferably 2.6 or less, from the viewpoint of achieving the introduction of a larger number of ethoxycarbonyl groups derived from CO2.

[0026] In the cellulose derivatives of this disclosure, the degree of substitution DS2 of the lower alkoxycarbonyl group is 0.1 or more and 2.0 or less. When the degree of substitution DS2 is within this range, the interactions between polymer chains can be easily maintained. From the viewpoint of utilizing CO2 and further improving thermoplasticity, the degree of substitution DS2 of the lower alkoxycarbonyl group is preferably 0.35 or more, more preferably 0.40 or more, and from the viewpoint of maintaining mechanical properties, it is preferably 0.80 or less, more preferably 0.60 or less.

[0027] In particular, from the standpoint of imparting excellent thermoplastic and mechanical properties to the cellulose derivative, it is preferable that the degree of substitution DS1 of the lower acyl group is 2.0 or more and 2.6 or less, and the degree of substitution DS2 of the lower alkoxycarbonyl group is 0.40 or more and 0.60 or less.

[0028] In this specification, the degree of substitution of the lower acyl group DS1 and the degree of substitution of the lower alkoxycarbonyl group DS2 are, 1 The measurement can be performed using 1H-NMR, specifically by the method described in the examples.

[0029] The cellulose derivatives of this disclosure may not have at least some of the hydrogen atoms of the hydroxyl groups contained in cellulose substituted. That is, the cellulose derivatives may have hydroxyl groups derived from cellulose.

[0030] In the cellulose derivatives of this disclosure, the residual amount of hydroxyl groups may be 1.9 or less, or it may be 0. If the residual amount of hydroxyl groups is 0, it means that there are no hydroxyl groups derived from cellulose in the cellulose derivative. The residual amount of hydroxyl groups is preferably 0.30 or less, and more preferably 0.20 or less, in order to fully obtain the effect of introducing lower acyl groups and lower alkoxy groups.

[0031] In this specification, "residual hydroxyl group amount" refers to the average number per glucose unit of the three hydroxyl groups in a cellulose derivative that remain without substituents being introduced.

[0032] In this specification, the residual amount of hydroxyl groups refers to the amount of cellulose obtained by benzoylating all the remaining hydroxyl groups of the glucose units in the cellulose derivative. 1 Alternatively, the characteristic peaks may be calculated from the integral ratio of characteristic peaks after performing 1H-NMR analysis, assuming a total of 3.0 substituents including the benzoyl group.

[0033] The cellulose derivatives of this disclosure may have lower alkyl groups as substituents on at least some of the hydrogen atoms of the hydroxyl groups contained in the cellulose. The biodegradability of the cellulose derivatives can be easily controlled by introducing lower alkyl groups. Preferably, the lower alkyl group is an ethyl group or a methyl group. The lower alkyl group may be a single group or two or more.

[0034] The degree of substitution DS3 of the lower alkyl group can be 1.9 or less, and may be 0. If the degree of substitution DS3 is 0, it means that the lower alkyl group is not present. If the lower alkyl group is present, the degree of substitution DS3 can be greater than 0, but from the viewpoint of controlling biodegradation, it is preferably 0.10 or more, more preferably 0.20 or more, and from the viewpoint of allowing sufficient introduction of lower alkoxycarbonyl groups by utilizing CO2, it is preferably 0.30 or less, and more preferably 0.25 or less.

[0035] In the present specification, the degree of substitution of the lower alkyl group can be determined by, for example, subjecting a cellulose derivative to alkali treatment to hydrolyze the lower acyl group and lower alkoxycarbonyl group, then acetylating the resulting product by the acetic anhydride / pyridine method, 1 analyzing and measuring the product by H-NMR, and calculating from the ratio of the peak area of the lower alkyl group to the peak area of the pyranose ring ((peak area of lower alkyl group) / (peak area of pyranose ring)).

[0036] In the cellulose derivative of the present disclosure, the substituents for the hydrogen atoms of the hydroxyl groups contained in cellulose are a lower acyl group and a lower alkoxycarbonyl group, or a lower acyl group, a lower alkoxycarbonyl group and a lower alkyl group.

[0037] In the cellulose derivative of the present disclosure, the sum of DS1, DS2, DS3 and the residual amount of hydroxyl groups is 3.0. DS3 may be 0, which in this case means that no lower alkyl group is present. In addition, the residual amount of hydroxyl groups may be 0, which in this case means that all hydrogen atoms of the hydroxyl groups contained in cellulose are substituted.

[0038] In the cellulose derivative of the present disclosure, the sum of DS1 and DS2 can be 1.1 or more and 3 or less. From the viewpoint of improving mechanical properties, the sum of DS1 and DS2 is preferably 1.5 or more, more preferably 2.0 or more. The sum of DS1 and DS2 may be 3, which in this case means that the lower alkyl group and residual hydroxyl groups are substantially absent.

[0039] However, the cellulose derivative of the present disclosure can be other than a cellulose derivative in which the lower acyl group is an acetyl group, the degree of substitution DS1 is 2.2, the lower alkoxycarbonyl group is an ethoxycarbonyl group, and the degree of substitution DS2 is 0.3.

[0040] The weight average molecular weight (Mw) of the cellulose derivative of the present disclosure is not particularly limited, and may be, for example, 0.10×10 5 to 1.00×10 6The following is possible, preferably 0.50 × 10 5 The above is true, and preferably 5.00 × 10 5 The following applies: The number-average molecular weight (Mn) of the cellulose derivatives of this disclosure is not particularly limited, for example, 0.10 × 10 5 The above 5.00 x 10 5 The following is possible, preferably 0.50 × 10 5 The above is true, and preferably 4.00 × 10 5 The following applies: In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) may be pullulan-equivalent values ​​measured by gel permeation chromatography (GPC).

[0041] Furthermore, the number-average degree of polymerization of the cellulose derivatives of this disclosure is not particularly limited and can be, for example, 100 or more and 1000 or less, preferably 200 or more, and preferably 800 or less. In this specification, the number-average degree of polymerization may be a value converted from a value measured by GPC.

[0042] [Method for producing cellulose derivatives] Another embodiment of the present disclosure is a method for producing a cellulose derivative of the present invention, which includes adding carbon dioxide gas to a solution containing cellulose in which at least some of the hydrogen atoms of the hydroxyl groups contained in the cellulose are substituted with lower acyl groups, a strong base, and an organic solvent, and then reacting it with a lower alkyl halogen.

[0043] The manufacturing method of this disclosure uses a solution containing cellulose in which at least some of the hydrogen atoms of the hydroxyl groups contained in the cellulose are replaced with lower acyl groups (hereinafter also referred to as "lower acyl-substituted cellulose"), a strong base, and an organic solvent.

[0044] In lower acyl-substituted cellulose, it is preferable that the hydrogen atoms of the hydroxyl groups contained in the cellulose are not substituted with anything other than lower acyl groups.

[0045] In lower acyl-substituted cellulose, the lower acyl group is preferably an acetyl group, propionyl group, butyryl group, hexanoyl group, etc., with acetyl group being the most preferred. The lower acyl group may be a single group or two or more groups.

[0046] The degree of substitution of the lower acyl group in lower acyl-substituted cellulose can be between 1.0 and 2.9. From the viewpoint of promoting the reaction by improving solubility in organic solvents during the reaction, the degree of substitution of the lower acyl group is preferably 1.5 or higher, more preferably 2.0 or higher, and from the viewpoint of introducing more ethoxycarbonyl groups derived from CO2, it is preferably 2.8 or lower, more preferably 2.6 or lower. The degree of substitution of the lower acyl group in lower acyl-substituted cellulose is substantially the same as the degree of substitution DS1 of the lower acyl group in the final product, the cellulose derivative.

[0047] The weight-average molecular weight (Mw) of lower acyl-substituted cellulose is not particularly limited, for example, 0.10 × 10⁻⁶. 5 The above 1.00 × 10 6 The following is possible, preferably 0.50 × 10 5 The above is true, and preferably 5.00 × 10 5 The following applies: The number-average molecular weight (Mn) of lower acyl-substituted cellulose is not particularly limited, for example, 0.10 × 10⁻⁶. 5 The above 5.00 x 10 5 The following is possible, preferably 0.50 × 10 5 The above is true, and preferably 4.00 × 10 5 The following applies:

[0048] Furthermore, the number-average degree of polymerization of the lower acyl-substituted cellulose is not particularly limited and can be, for example, 100 to 1000, preferably 200 or more, and preferably 800 or less.

[0049] Examples of strong bases include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; quaternary ammonium hydroxides such as tetramethylammonium hydroxide (TMAH) and tetraethylammonium hydroxide (TEAH); organic bases having an amidine skeleton such as 1,8-diazabicyclo[5.4.0]undeca-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,5,7-triazabicyclo[4.4.0]deca-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]deca-5-ene; and organic bases having a guanidine skeleton such as 1,1,3,3-tetramethylguanidine (also known as TMG). In particular, organic bases having an amidine skeleton, such as DBU and DBN, are advantageous in that they deprotonate the hydroxyl groups of cellulose, and the cellulose carbonate produced when the deprotonated hydroxyl groups react with carbon dioxide gas (CO2) is readily soluble in organic solvents (e.g., dimethyl sulfoxide). The strong base may be used alone or in combination of two or more types.

[0050] The amount of strong base can be between 1 / 4 mole and 4 moles per mole of glucose units contained in the lower acyl-substituted cellulose, preferably 1 / 3 mole or more, more preferably 1 mole or more, and preferably 3 moles or less, and more preferably 2 moles or less. From the viewpoint of obtaining good thermal fluidity, a smaller amount of strong base is preferable, and for example, it is advantageous to have 2 moles or less per mole of glucose units.

[0051] From the viewpoint of solubility of lower acyl-substituted cellulose, aprotic polar solvents are preferred as organic solvents, such as amide solvents like dimethyl sulfoxide, dimethylformamide, N,N-dimethylacetamide, N-methylpiperidone, and 1,3-dimethyl-2-imidazolidinone; sulfolanes; and cyclic ether solvents like tetrahydrofuran. Among these, cyclic ether solvents such as dimethyl sulfoxide and tetrahydrofuran are preferred from the viewpoint of affinity with the reactants and products. The organic solvent may be used alone or in combination of two or more types.

[0052] The amount of organic solvent can be set as appropriate. For example, it can be 8 mL to 50 mL per 1 g of lower acyl-substituted cellulose, preferably 12 mL or more, more preferably 25 mL or more, and preferably 40 mL or less, and more preferably 30 mL or less.

[0053] In preparing the solution, it is preferable to mix a lower acyl base with an organic base, and then a strong base. In the solution, the strong base reacts with the remaining hydroxyl groups of cellulose, causing deprotonation. These deprotonated hydroxyl groups then form bonds with carbon dioxide gas (CO2) added in a subsequent step, react with the halogenated lower alkyl, and introduce lower alkoxycarbonyl groups.

[0054] Next, carbon dioxide gas is added to the obtained solution. The addition of carbon dioxide gas can be done in a sealed container. From the viewpoint of promoting the reaction, the amount of carbon dioxide gas can be in excess of the remaining hydroxyl groups of the lower acyl group-substituted cellulose used. For example, it can be 1 mole or more per mole of remaining hydroxyl groups of the lower acyl group-substituted cellulose, preferably 2 moles or more, and more preferably 3 moles or more. There is no particular upper limit to the amount of carbon dioxide gas, but for example, it can be 5 moles or less per mole of remaining hydroxyl groups of the cellulose used.

[0055] After adding carbon dioxide gas, stirring is performed. The stirring time can be set as appropriate, for example, from 1 hour to 48 hours. The stirring temperature can be set as appropriate, for example, from 10°C to 90°C, preferably from 25°C to 40°C, and may also be performed at room temperature.

[0056] A lower halogenated lower alkyl group is added to a solution to which carbon dioxide gas has been added and reacted to introduce a lower alkoxycarbonyl group into the lower acyl-substituted cellulose.

[0057] Examples of halogenated lower alkyls include fluorinated lower alkyls, bromide lower alkyls, and iodide lower alkyls. From the standpoint of ease of reaction and ease of synthesis, iodide lower alkyls are preferred.

[0058] The lower alkyl portion of the halogenated lower alkyl group should be selected to correspond to the lower alkyl portion of the lower alkoxycarbonyl group to be introduced. For example, when introducing an ethoxycarbonyl group, ethyl halogen can be used as the halogenated lower alkyl group, and ethyl iodide is preferred.

[0059] The halogenated lower alkyl can be in an amount of 1 / 4 mole to 4 moles per mole of glucose units contained in the lower acyl-substituted cellulose, preferably 1 / 3 mole or more, more preferably 1 mole or more, and preferably 3 moles or less, and more preferably 2 moles or less.

[0060] The reaction temperature can be set as appropriate, for example, between 10°C and 90°C, preferably between 25°C and 40°C, and the reaction may also be carried out at room temperature. The reaction time can be set as appropriate, for example, between 1 hour and 48 hours.

[0061] The cellulose derivative of this disclosure can be obtained by reprecipitation of the reaction solution using a solvent such as ethanol and then filtering the solution.

[0062] [Resin composition] Another embodiment of the present disclosure is a resin composition comprising a cellulose derivative of the present disclosure. The resin composition of the present disclosure may optionally contain various additives.

[0063] Examples of additives include fillers (organic fillers, inorganic fillers, etc.), flame retardants, UV absorbers, antioxidants, plasticizers, mold release agents, colorants (dyes, pigments, etc.), fragrances, antifouling agents, and humectants. Additives may be used individually or in combination of two or more types.

[0064] The resin compositions of this disclosure may contain polymer components other than the cellulose derivatives of this disclosure. The polymer components may be thermoplastic polymers or thermosetting polymers, and may be one or more of them.

[0065] The resin compositions of this disclosure may contain a solvent. The solvent may be an inorganic solvent (e.g., water) or an organic solvent (e.g., a lower alcohol, a polyhydric alcohol), and may be a single solvent or two or more solvents.

[0066] The resin composition of this disclosure preferably contains 60% by mass or more of the cellulose derivative of this disclosure in its solid content, and more preferably 80% by mass or more. The cellulose of this disclosure may be 100% by mass in the solid content, but may be 90% by mass or less in order to fully obtain the effects of additives and the like.

[0067] [Molded body] A further embodiment of the present disclosure is a molded article obtained by molding the resin composition of the present disclosure. Since the cellulose derivative of the present disclosure has excellent thermoplasticity, the resin composition of the present disclosure has good moldability. For example, a molded article can be obtained by melting the resin composition of the present disclosure by heating or the like and then molding it. The molding method is not particularly limited and examples include injection molding, extrusion molding, blow molding, etc. The heating temperature can be, for example, 120°C to 150°C. The molded article may be obtained by molding the cellulose derivative of the present invention.

[0068] Each embodiment disclosed herein can be combined with any other features disclosed herein. Each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications are permitted as appropriate, without departing from the spirit of this disclosure. Furthermore, each invention relating to this disclosure is not limited by the embodiments or the following examples, but is limited solely by the claims. [Examples]

[0069] The present disclosure will be explained in more detail below with reference to examples. However, the present disclosure is not limited to the following examples.

[0070] [Example 1] In a 50 mL reaction vessel, add cellulose diacetate (CDA; acetyl substitution degree 2.15; Mn: 1.00 × 10⁶). 5 Mw: 1.71 × 10 5 2.0 g of (number average degree of polymerization 396) was added, and 25 mL of dimethyl sulfoxide (DMSO) was added to it. A stirrer was added to the reaction vessel and the mixture was stirred for 30 minutes to prepare a CDA solution in DMSO (CDA / DMSO solution). To this solution, 0.39 mL of 1,8-diazabicyclo[5.4.0]undeca-7-ene (DBU) was added so that the ratio of moles of DBU to moles of glucose units (AGU) of CDA (DBU / AGU) was 1 / 3. Subsequently, a balloon containing approximately 1 liter of carbon dioxide (CO2) was quickly connected to a sealed reaction vessel, and CO2 gas was added. The mixture was then stirred for 1 hour. During this time, the temperature was maintained at room temperature. Subsequently, the reaction vessel was immersed in a water bath at room temperature, and while stirring, 0.21 mL of EtI was added and the reaction proceeded until the ratio of moles of iodoethane (EtI) to moles of glucose units (AGU) in CDA (EtI / AGU) was 1 / 3. The temperature was maintained at room temperature throughout the process. After stirring for 1 hour, the reaction solution was added to 300 mL of ethanol in a 500 mL beaker while stirring the ethanol. After stirring for about 10 minutes, the resulting white precipitate was filtered through a PTFE membrane filter with a pore size of 1 μm, and the filtrate was collected. The collected filtrate was transferred entirely to a 500 mL beaker containing 300 mL of ethanol, and stirred overnight at room temperature. After stirring overnight at room temperature, it was filtered in the same manner as described above, and the filtrate was collected. The collected filtrate was transferred entirely to a 500 mL beaker containing 100 mL of ethanol, and stirred for 2 hours. After stirring, it was filtered in the same manner as described above, and the filtrate was collected. The collected filtrate was again transferred entirely to a 500 mL beaker containing 100 mL of ethanol, and stirred for 2 hours. After stirring, it was filtered in the same manner as described above, and the filtrate was collected. The filtered material was transferred to 100-500 mL beakers and air-dried overnight at 55°C. The dried material was collected and further dried in a vacuum dryer at 40°C to obtain 2.1 g of the cellulose derivative of Example 1.

[0071] [Example 2] Except for using 1.17 mL of DBU so that the ratio of moles of DBU to moles of AGU (DBU / AGU) was 1, and using 0.63 mL of EtI so that the ratio of moles of EtI to moles of AGU (EtI / AGU) was 1, 2.2 g of the cellulose derivative of Example 2 was obtained in the same manner as in Example 1.

[0072] [Example 3] Except for using 2.34 mL of DBU so that the ratio of moles of DBU to moles of AGU (DBU / AGU) was 2, and using 1.26 mL of EtI so that the ratio of moles of EtI to moles of AGU (EtI / AGU) was 2, 2.4 g of the cellulose derivative of Example 3 was obtained in the same manner as in Example 1.

[0073] [Example 4] In a 50 mL reaction vessel, add cellulose diacetate (CDA; acetyl substitution degree 2.15; Mn: 1.00 × 10⁶). 5 Mw: 1.71 × 10 5 2.0 g of (number average degree of polymerization 396) was added, and a mixed solvent of 12.5 mL of DMSO and 12.5 mL of tetrahydrofuran (THF) was added. A stirrer was added to the reaction vessel and the mixture was stirred for 30 minutes to prepare a CDA solution in DMSO and THF (CDA / DMSO / THF solution). To this solution, 3.51 mL of DBU was added so that the ratio of moles of DBU to moles of glucose units (AGU) in CDA (DBU / AGU) was 3. Subsequently, a balloon containing approximately 1 liter of carbon dioxide (CO2) was quickly connected to a sealed reaction vessel, and CO2 gas was added. The mixture was then stirred for 1 hour. During this time, the temperature was maintained at room temperature. Subsequently, the reaction vessel was immersed in a water bath at room temperature, and while stirring, 1.89 mL of EtI was added so that the ratio of moles of iodoethane (EtI) to moles of glucose units (AGU) in CDA (EtI / AGU) was 3, and the reaction was carried out. The temperature was maintained at room temperature throughout. After stirring for 1 hour, the reaction solution was added to 300 mL of ethanol in a 500 mL beaker while stirring the ethanol. After stirring for about 10 minutes, the resulting white precipitate was filtered through a PTFE membrane filter with a pore size of 1 μm, and the filtrate was collected. The collected filtrate was transferred entirely to a 500 mL beaker containing 300 mL of ethanol and stirred overnight at room temperature. After stirring overnight at room temperature, it was filtered in the same manner as described above, and the filtrate was collected. The collected filtrate was transferred entirely to a 500 mL beaker containing 100 mL of ethanol and stirred for 2 hours. After stirring, it was filtered in the same manner as described above, and the filtrate was collected. The collected filtrate was again transferred entirely to a 500 mL beaker containing 100 mL of ethanol and stirred for 2 hours. After stirring, it was filtered in the same manner as described above, and the filtrate was collected. All of the filtrate was transferred to 100-500 mL beakers and air-dried overnight at 55°C. The dried material was collected and further dried in a vacuum dryer at 40°C to obtain the cellulose derivative of Example 4.

[0074] [Comparative Example 1] Cellulose diacetate (CDA) used as a raw material in Examples 1-4. Acetyl substitution degree 2.15. Mn: 1.00 × 10⁻⁶ 5 Mw: 1.71 × 10 5 The number-average degree of polymerization is 396.

[0075] [Comparative Example 2] 1 g of cellulose microcrystals (MCC; Merk's "microcrystalline for thin-layer chromatography"; CAS number: 9004-34-6) was added to a 50 mL reaction vessel, and then 25 mL of DMSO was added. To this solution, 8.28 mL of DBU was added so that the ratio of moles of DBU to moles of glucose units (AGU) in MCC (DBU / AGU) was 3. Thereafter, a balloon containing about 1 L of carbon dioxide (CO₂) was promptly connected to the sealed reaction vessel, CO₂ gas was added, and the mixture was stirred for 1 hour. During this period, the temperature was maintained at room temperature. Thereafter, the reaction vessel was immersed in a room-temperature water bath, and while stirring, 4.66 mL of EtI was added to cause a reaction such that the ratio of the number of moles of iodoethane (EtI) to the number of moles of glucose units (AGU) in MCC (EtI / AGU) was 3. During this period, the temperature was maintained at room temperature. After stirring for 1 hour, the reaction solution was added to 300 mL of ethanol in a 500 mL beaker while the ethanol was being stirred. After stirring for about 10 minutes, the resulting white precipitate was filtered through a PTFE membrane filter with a pore size of 1 μm, and the filtered material was collected. All of the collected filtered material was transferred to a 500 mL beaker containing 300 mL of ethanol, and the mixture was stirred overnight at room temperature. After stirring overnight at room temperature, this was filtered in the same manner as the method described above, and the filtered material was collected. All of the collected filtered material was transferred to a 500 mL beaker containing 100 mL of ethanol, and the mixture was stirred for 2 hours. After stirring, this was filtered in the same manner as the method described above, and the filtered material was collected. All of the collected filtered material was again transferred entirely to a 500 mL beaker containing 100 mL of ethanol, and the mixture was stirred for 2 hours. After stirring, this was filtered in the same manner as the method described above, and the filtered material was collected. All of the filtered material was transferred to a 100 to 500 mL beaker, and dried by blowing air at 55°C overnight. The dried product was collected and further dried in a vacuum dryer at 40°C to obtain the cellulose derivative of Comparative Example 2.

[0076] The following evaluations were performed on the cellulose derivatives of the Examples and Comparative Examples.

[0077] <FT-IR Spectrum Measurement> The FT-IR spectrum measurement was performed using a Fourier transform infrared spectrometer Spectrum 3 MIR-NIR manufactured by PerkinElmer. The measurement was carried out by the ATR method, with the number of integrations set to 64 or 32, and a resolution of 4 cm -1 , and the measurement wavelength was set to 4000-400 cm -1 . Charts of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Figures 1 to 6.

[0078] < 1 H-NMR measurement> The cellulose derivatives of Examples 2-3 were dissolved in deuterated chloroform. 1 The samples were subjected to 1H-NMR measurements. The sample concentration was 10 mg / mL, and the measurements were performed under the following conditions: observation time 0.15 seconds, relaxation time 1.0 seconds, observation frequency 300.1 MHz, and 16 integration cycles. The chemical shift values ​​of the obtained spectra were expressed in ppm, with the methyl group peak of the internal standard trimethylsilane (TMS) as the reference (0 ppm). All measurements were performed using a 300-MHz NMR spectrometer (Varian INOVA300). 1 The degree of substitution of the ethoxycarbonyl group of CDA (DS) can be determined from the H-NMR measurement results using the following formula. CO2Et ) was calculated here DS CO2Et This indicates the number of glucose units (AGU) in which three hydroxyl groups are replaced by ethoxycarbonyl groups. CO2CH2CH3 This is the peak area of ​​the ethoxycarbonyl group, and S COCH3 This indicates the peak area of ​​the acetyl group. DSacetyl is the degree of acetyl substitution, which is 2.15 in Examples 1-4 and Comparative Example 1.

number

[0079] For Comparative Example 2, since the cellulose derivative was insoluble in deuterated chloroform, it was acetylated using the acetic anhydride / pyridine method, then dissolved in deuterated chloroform, and measured in the same manner as above. Degree of substitution of the ethoxycarbonyl group (DS) CO2Et The value was calculated using the following formula.

number

[0080] Figures 7-9 show charts for Examples 2-3 and Comparative Example 2. Table 1 shows the results for the degree of substitution.

[0081] <Thermodynamic initiation temperature (thermoplasticity evaluation)> The thermal fluidization onset temperature of the cellulose derivatives in the examples and comparative examples was measured using a flow tester. The thermal fluidization onset temperature was measured using a constant-test force-type capillary tube rheometer and flow tester CFT-500EX manufactured by Shimadzu Corporation, and the temperature was increased. The measurement conditions were as follows. The results are shown in Table 1. Sample: 1.0-1.1g Load: 50kgf Die dimensions: Diameter 1.0mm, Length 1.0mm Plunger area: 1 cm 2 Preheating time: 120s Starting temperature: 50°C Heating rate: 5.0°C / min

[0082] <Mechanical properties> The cellulose derivatives of the examples and comparative examples were arranged in a rectangle (4 × 13 mm). 2 ) Place in mold, 120 o C. By applying uniaxial pressure at 120 MPa for 5 minutes, a prismatic molded product (4 × 13 × (2.3-3.0) mm) is produced. 3 ) was created. The density was determined from the weight and volume of the obtained molded body. The results are shown in Table 1.

[0083] The obtained molded bodies were subjected to a three-point bending test using a bending strength testing machine "MZ-250" (manufactured by Maruto Co., Ltd.). The distance L between the supports was 8 mm, and the crosshead speed for the bending test was 0.5 mm / min. Based on the test results, the three-point bending strength (MPa) and three-point bending strain were calculated using the following formulas. 3-point bending strength: σb=(3PL) / (2wt 2 ) Three-point bending strain: εb = (600st) / (L 2 ) In the formula, P is the maximum load (N), L is the distance between supports (mm), w is the width of the specimen (mm), t is the thickness of the specimen (mm), and s is the maximum deflection (mm).

[0084] The flexural modulus Eb(GPa) of each molded product was calculated from the slope of the stress-strain curve obtained from the three-point bending test.

[0085] Destructive energy (MJ / m 3 The area was calculated from the stress-strain curve and the horizontal axis.

[0086] The results are shown in Table 1. [Table 1]

[0087] Table 1 shows that the cellulose derivatives in the examples exhibit excellent thermoplastic and mechanical properties. In particular, Example 2 (acetyl substitution degree 2.15, ethoxycarbonyl substitution degree 0.45) and Example 3 (acetyl substitution degree 2.15, ethoxycarbonyl substitution degree 0.52) have low thermal fluidity initiation temperatures and exhibit excellent moldability. [Industrial applicability]

[0088] This disclosure provides novel cellulose derivatives along with methods for producing them. The cellulose derivatives of this disclosure exhibit excellent thermoplastic and mechanical properties, can be used in a variety of applications, and have high industrial utility. The methods for producing these derivatives of this disclosure use CO2 as a raw material and contribute to the reduction of CO2 in the atmosphere.

Claims

1. At least some of the hydrogen atoms in the hydroxyl groups contained in cellulose are substituted with lower acyl groups and lower alkoxycarbonyl groups. Degree of substitution of lower acyl groups (DS) １ The value is between 1.0 and 2.9, Degree of substitution of lower alkoxycarbonyl groups (DS) ２ The value is between 0.1 and 2.

0. Cellulose derivatives.

2. The cellulose derivative according to claim 1, wherein the lower acyl group is an acetyl group.

3. The cellulose derivative according to claim 1, wherein the lower alkoxycarbonyl group is an ethoxycarbonyl group.

4. Degree of substitution DS of the lower alkoxycarbonyl group ２ The cellulose derivative according to claim 1, wherein the ratio is 0.35 or more and 2.0 or less.

5. Degree of substitution of lower acyl groups (DS) １ The value is between 2.0 and 2.6, Degree of substitution of lower alkoxycarbonyl groups (DS) ２ A cellulose derivative according to claim 1, wherein the ratio is 0.40 or more and 0.60 or less.

6. The cellulose derivative according to claim 1, wherein at least some of the hydrogen atoms of the hydroxyl groups contained in the cellulose are further substituted with lower alkyl groups.

7. Degree of substitution of lower alkyl groups (DS) ３ The cellulose derivative according to claim 6, wherein the ratio is 0.10 or more and 0.30 or less.

8. The cellulose derivative according to claim 6, wherein the lower alkyl group is an ethyl group.

9. A resin composition comprising a cellulose derivative according to any one of claims 1 to 8.

10. A molded article obtained by molding the resin composition described in claim 9.

11. A method for producing a cellulose derivative according to any one of claims 1 to 8, comprising adding carbon dioxide gas to a solution containing cellulose in which at least some of the hydrogen atoms of the hydroxyl groups contained in the cellulose are replaced with lower acyl groups, a strong base, and an organic solvent, and then reacting it with a halogenated lower alkyl group.

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