Ethyl cellulose, method for producing ethyl cellulose with low degree of polymerization, and method for lowering degree of polymerization of ethyl cellulose

Abstract

The present invention provides a method for producing an ethyl cellulose with a low degree of polymerization.　Provided is a method for producing an ethyl cellulose with a low degree of polymerization, the method including: a step for preparing a starting material ethyl cellulose; and a step for subjecting the starting material ethyl cellulose to ethanolysis in the presence of an acid catalyst and ethanol so as to obtain an ethyl cellulose with a low degree of polymerization in which the degree of polymerization of the starting material ethyl cellulose is decreased.

Description

Ethyl cellulose, method for producing low-polymerization ethyl cellulose, and method for reducing the degree of polymerization of ethyl cellulose

[0001] The present disclosure relates to ethyl cellulose, a method for producing low-polymerization ethyl cellulose, and a method for reducing the polymerization degree of ethyl cellulose.

[0002] Toward the realization of a sustainable society, there is a need to expand the use of renewable biomass resources, especially cellulose, which is the most abundant organic resource on Earth as the main component of plant bodies.

[0003] Cellulose possesses chemical modification ability, hydrogen bonding ability, semi-rigidity, and chirality, and these one-dimensional structural properties allow molecular organization to be achieved relatively easily (Non-Patent Document 1).

[0004] Y. Nishio, Adv. Polym. Sci. , 205, 97 (2006).

[0005] One of the molecular organization forms of cellulose derivatives is the liquid crystal phase. Due to the semi-rigidity and chirality of the molecular chains, cellulose derivatives form a cholesteric liquid crystal structure (a structure in which thin layers of molecules aligned in one direction are stacked in a helical configuration). To date, control of the cholesteric structure using stimuli such as electric fields, light, pressure, and humidity has been investigated (Non-Patent Document 1).

[0006] In designing functional materials based on cellulose derivatives, it is important to improve their responsiveness to external stimuli. One possible way to improve responsiveness is to decrease the degree of polymerization of the cellulose derivatives and increase the mobility of the molecular chains.

[0007] Commercially available cellulose derivatives include, for example, ethyl cellulose. Ethyl cellulose is used in a variety of fields, including sheet molding, casting, extrusion, pressure molding, coating (e.g., hot melt, gel lacquer, lacquer, adhesive, printing ink, medical coating agent, etc.), and emulsification. Ethyl cellulose is produced by depolymerizing pulp with alkali (sodium hydroxide) and then ethylating the resulting alkali cellulose with ethyl chloride.

[0008] However, conventional ethyl cellulose has a high degree of polymerization (a number-average degree of polymerization (DPn) of more than 100 or a weight-average degree of polymerization (DPw) of more than 400), and it is difficult to design functional materials using ethyl cellulose.

[0009] A primary object of the present disclosure is to provide a method for producing low-polymerization ethyl cellulose. Another object of the present disclosure is to provide low-polymerization ethyl cellulose and a method for reducing the polymerization degree of ethyl cellulose.

[0010] As a result of extensive research, the inventors of the present disclosure have found that ethanolysis of starting ethyl cellulose having a high degree of polymerization in the presence of an acid catalyst and ethanol can produce low-polymerization ethyl cellulose, in which the degree of polymerization of the starting ethyl cellulose is reduced while the degree of substitution is substantially maintained. The present disclosure is an invention that was completed based on these findings and through further research.

[0011] That is, the present disclosure provides the following aspects of the invention. [Item 1] A method for producing low-polymerization ethyl cellulose, comprising the steps of: preparing a starting ethyl cellulose; and ethanololyzing the starting ethyl cellulose in the presence of an acid catalyst and ethanol to obtain low-polymerization ethyl cellulose, in which the degree of polymerization of the starting ethyl cellulose is reduced. [Item 2] A method for producing low-polymerization ethyl cellulose according to Item 1, in which the starting ethyl cellulose has a number-average degree of polymerization (DPn) of more than 180. [Item 3] A method for producing low-polymerization ethyl cellulose according to Item 1 or 2, in which the starting ethyl cellulose has a weight-average degree of polymerization (DPw) of more than 500. [Item 4] A method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 3, in which the starting ethyl cellulose has a degree of ethyl substitution (DS) of 1.0 to 3.0. [Item 5] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 4, wherein the acid catalyst is at least one selected from the group consisting of p-toluenesulfonic acid, inorganic acids, organic acids, and cation exchange resins. [Item 6] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 5, wherein the amount of the acid catalyst used is 1 to 30 equivalents / anhydroglucose unit (AGU). [Item 7] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 6, wherein the reaction temperature is 20 to 100°C. [Item 8] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 7, wherein the number-average degree of polymerization (DPn) of the low-polymerization ethyl cellulose is 180 or less. [Item 9] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 8, wherein the number-average degree of polymerization (DPn) of the low-polymerization ethyl cellulose is 100 or less. [Item 10] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 9, wherein the low-polymerization ethyl cellulose has a weight-average degree of polymerization (DPw) of 500 or less. [Item 11] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 10, wherein the low-polymerization ethyl cellulose has a weight-average degree of polymerization (DPw) of 260 or less.[Item 12] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 11, wherein the degree of ethyl substitution (DS) of the low-polymerization ethyl cellulose is 1.0 to 3.0. [Item 13] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 12, wherein the number-average molecular weight (Mn) of the low-polymerization ethyl cellulose is 30,000 or less. [Item 14] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 13, wherein the weight-average molecular weight (Mw) of the low-polymerization ethyl cellulose is 80,000 or less. [Item 15] The method for producing low-polymerization ethyl cellulose according to any one of Items 1 to 14, wherein the polydispersity (Mw / Mn) of the low-polymerization ethyl cellulose is 10 or less. [Item 16] The method for producing a low-polymerization ethylcellulose according to any one of Items 1 to 15, wherein the low-polymerization ethylcellulose has only a hydroxyl group at the C4 position of the non-reducing terminal glucose residues of the remaining starting ethylcellulose, excluding molecules containing non-reducing terminal glucose residues from the starting ethylcellulose. [Item 17] Ethylcellulose having a number-average degree of polymerization (DPn) of 35 or less. [Item 18] The ethylcellulose according to Item 17 having a weight-average degree of polymerization (DPw) of 90 or less. [Item 19] The ethylcellulose according to Item 17 or 18, which exhibits liquid crystallinity. [Item 20] The ethylcellulose according to any one of Items 17 to 19, having a degree of ethyl substitution (DS) of 1.0 to 3.0. [Item 21] The ethylcellulose according to any one of Items 16 to 20, having a number-average molecular weight (Mn) of 7,300 or less. [Item 22] The ethylcellulose according to any one of Items 16 to 21, having a weight-average molecular weight (Mw) of 20,000 or less. [Item 23] The ethyl cellulose according to any one of Items 17 to 22, having a polydispersity (Mw / Mn) of 10 or less. [Item 24] The ethyl cellulose according to any one of Items 17 to 23, wherein the C4 position of the non-reducing terminal glucose residues of the remaining starting ethyl cellulose, excluding molecules containing a non-reducing terminal glucose residue from the starting ethyl cellulose, is solely a hydroxyl group. [Item 25] A method for reducing the degree of polymerization of ethyl cellulose, comprising ethanolyzing the starting ethyl cellulose in the presence of an acid catalyst and ethanol to reduce the degree of polymerization of the starting ethyl cellulose.[Item 26] Ethyl cellulose having a number average degree of polymerization (DPn) of 35 or less. [Item 27] ​​Ethyl cellulose having a weight average degree of polymerization (DPw) of 90 or less. [Item 28] Ethyl cellulose exhibiting liquid crystallinity.

[0012] According to the present disclosure, it is possible to provide a method for producing low-polymerization ethyl cellulose. Furthermore, according to the present disclosure, it is also possible to provide low-polymerization ethyl cellulose and a method for reducing the polymerization degree of ethyl cellulose.

[0013] The method for producing low-polymerization ethyl cellulose according to the present disclosure is characterized by comprising the following steps: a step of preparing a raw material ethyl cellulose; and a step of subjecting the raw material ethyl cellulose to ethanolysis in the presence of an acid catalyst and ethanol to obtain low-polymerization ethyl cellulose in which the degree of polymerization of the raw material ethyl cellulose has been reduced.

[0014] According to the method for producing low-polymerization ethyl cellulose of the present disclosure, it is possible to suitably produce low-polymerization ethyl cellulose in which the polymerization degree of the raw material ethyl cellulose is reduced. Hereinafter, the method for producing low-polymerization ethyl cellulose (method for reducing the polymerization degree of ethyl cellulose) of the present invention and the low-polymerization ethyl cellulose will be described in detail.

[0015] In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Separately described upper and lower limits, upper and lower limits, or lower and lower limits may be combined to form a numerical range. In the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0016] Additionally, each feature disclosed herein can be combined with any other feature disclosed herein.

[0017] 1. Method for Producing Low-Polymerization Ethyl Cellulose The method for producing low-polymerization ethyl cellulose according to the present disclosure includes the steps of: preparing a starting material ethyl cellulose; and ethanololyzing the starting material ethyl cellulose in the presence of an acid catalyst and ethanol to obtain low-polymerization ethyl cellulose in which the degree of polymerization of the starting material ethyl cellulose has been reduced.

[0018] In the method for producing low polymerization degree ethyl cellulose according to the present disclosure, the raw material ethyl cellulose to be subjected to low polymerization is not particularly limited, and commercially available products can be used.

[0019] The number average degree of polymerization (DPn) of the raw material ethyl cellulose is not particularly limited. For commercially available products, the number average degree of polymerization (DPn) of the raw material ethyl cellulose is, for example, more than 180, 185 or more, or 200 or more, and is 500 or less, 400 or less, or 300 or less. Examples of the number average degree of polymerization (DPn) range include more than 180 and 500 or less, more than 180 and 400 or less, more than 180 and 300 or less, about 185 to 500, about 185 to 400, about 185 to 300, about 200 to 500, about 200 to 400, and about 200 to 300.

[0020] The weight-average degree of polymerization (DPw) of the raw material ethyl cellulose is not particularly limited. The number-average degree of polymerization (DPn) of the raw material ethyl cellulose, if commercially available, is, for example, more than 500, 505 or more, or 550 or more, and is 10,000 or less, 1,000 or less, and the range of the weight-average degree of polymerization (DPw) may be more than 500 and 10,000 or less, more than 500 and 1,000 or less, about 505 to 10,000, about 505 to 1,000, about 550 to 10,000, or about 550 to 1,000.

[0021] The degree of ethyl substitution (DS) of the starting ethyl cellulose is also not particularly limited. In the method for producing low-polymerization ethyl cellulose of the present disclosure, there is no significant difference between the degree of ethyl substitution (DS) of the starting ethyl cellulose and the degree of ethyl substitution (DS) of the low-polymerization ethyl cellulose, so the degree of ethyl substitution (DS) of the starting ethyl cellulose can be selected depending on the desired degree of ethyl substitution (DS) of the low-polymerization ethyl cellulose. Examples of the degree of ethyl substitution (DS) of the starting ethyl cellulose include 1.0 to 3.0, 1.5 to 3.0, and 2.0 to 3.0.

[0022] The acid catalyst is not particularly limited as long as it can promote the ethanolysis reaction of raw material ethyl cellulose in the presence of ethanol. Specific examples of the acid catalyst include inorganic acids such as p-toluenesulfonic acid, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and boric acid; organic acids such as acetic acid and formic acid; and cation exchange ion exchange resins. Only one type of acid catalyst may be used for the ethanolysis, or two or more types may be used.

[0023] The amount of the acid catalyst used is not particularly limited, as long as it is an amount that can promote the ethanolysis reaction of the starting ethyl cellulose in the presence of ethanol. The amount of the acid catalyst used is preferably 1 equivalent / anhydroglucose unit (AGU) or more, more preferably 3 equivalents / anhydroglucose unit (AGU) or more, even more preferably 5 equivalents / anhydroglucose unit (AGU) or more, preferably 10 equivalents / anhydroglucose unit (AGU) or more, and even more preferably 15 equivalents / anhydroglucose unit (AGU) or more, and the upper limit is, for example, 30 equivalents / anhydroglucose unit (AGU) or less, and preferred ranges include 1 to 30 equivalents / anhydroglucose unit (AGU), 1 to 10 equivalents / anhydroglucose unit (AGU), and 1 to 5 equivalents / anhydroglucose unit (AGU).

[0024] The amount of ethanol used is not particularly limited as long as the ethanololysis of the starting ethyl cellulose can proceed in the presence of ethanol. From the viewpoint of favorable ethanololysis of the starting ethyl cellulose, it is preferable to use an excess amount of ethanol relative to the starting ethyl cellulose.

[0025] In the method for producing low-polymerization ethyl cellulose according to the present disclosure, it is preferable to use ethanol as a solvent and ethanolize raw ethyl cellulose in an ethanol solvent containing an acid catalyst. The solvent used for ethanololysis contains at least ethanol. That is, ethanol alone may be used as the solvent for ethanololysis, or ethanol may be used in combination with another solvent.

[0026] Examples of other solvents include aprotic solvents. Examples of aprotic solvents include sulfoxide solvents such as DMSO (dimethyl sulfoxide), methyl ethyl sulfoxide, and diethyl sulfoxide; alkylamide solvents such as N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dimethylacetamide (DMAC), and N,N-diethylacetamide; and pyrrolidone solvents such as N-methyl-2-pyrrolidone (NMP), 2-pyrrolidone, and 3-pyrrolidone. When using other solvents, the proportion of ethanol in the total amount of solvent used for ethanololysis is preferably 10% by mass or more, more preferably 50% by mass or more, even more preferably 80% by mass or more, and preferably 90% by mass or more. Furthermore, a small amount of water may be used in combination with ethanol as another solvent, within a range in which the low polymerization degree ethyl cellulose of the present disclosure can be suitably obtained.

[0027] The reaction temperature when ethanolyzing raw ethyl cellulose in the presence of an acid catalyst and ethanol is not particularly limited as long as the ethanolysis of raw ethyl cellulose in the presence of ethanol can proceed. The reaction temperature is preferably 20°C or higher, more preferably 30°C or higher, even more preferably 40°C or higher, even more preferably 50°C or higher, and preferably 60°C or higher. The upper limit is, for example, 100°C or lower, 90°C or lower, and preferred ranges include about 20 to 100°C, about 20 to 90°C, about 30 to 100°C, about 30 to 90°C, about 40 to 100°C, about 40 to 90°C, about 50 to 100°C, about 50 to 90°C, about 60 to 100°C, and about 60 to 90°C.

[0028] The reaction time when ethanolyzing the starting ethyl cellulose in the presence of an acid catalyst and ethanol is not particularly limited as long as the ethanolysis of the starting ethyl cellulose in the presence of ethanol can proceed. The reaction time is preferably 1 hour or more, more preferably 2 hours or more, and even more preferably 3 hours or more. The upper limit is, for example, 24 hours or less, 20 hours or less, and preferred ranges include about 1 to 24 hours, about 1 to 20 hours, about 2 to 24 hours, about 2 to 20 hours, about 3 to 24 hours, and about 3 to 20 hours.

[0029] After ethanolysis of the raw material ethyl cellulose, the acid catalyst can be neutralized by adding an alkali in an amount equivalent to the acid catalyst. The alkali is not particularly limited as long as it can neutralize the acid catalyst. Specific examples of alkali include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia. Only one type of alkali may be used, or two or more types may be used. Alternatively, the alkali to be used may be dissolved in water and then added.

[0030] Furthermore, the low polymerization degree ethyl cellulose can also be isolated by utilizing known purification and concentration methods.

[0031] As described above, by subjecting raw material ethyl cellulose to ethanololysis in the presence of an acid catalyst and ethanol, low-polymerization ethyl cellulose, in which the degree of polymerization of the raw material ethyl cellulose is reduced, can be obtained.

[0032] The number average degree of polymerization (DPn) of the low-polymerization ethyl cellulose obtained by the method for producing low-polymerization ethyl cellulose of the present disclosure is preferably 180 or less, more preferably 150 or less, even more preferably 120 or less, and even more preferably 100 or less, and particularly preferably 80 or less, 60 or less, 35 or less, etc. The lower limit is, for example, 1 or more, preferably 5 or more, and even more preferably 10 or more. Preferred ranges include about 1 to 180, about 1 to 150, about 1 to 120, about 1 to 100, about 1 to 60, about 1 to 35, about 5 to 180, about 5 to 150, about 5 to 120, about 5 to 100, about 5 to 60, about 5 to 35, about 10 to 180, about 10 to 150, about 10 to 120, about 10 to 100, about 10 to 60, about 10 to 35, etc.

[0033] The weight-average degree of polymerization (DPw) of the low-polymerization ethyl cellulose obtained by the method for producing low-polymerization ethyl cellulose of the present disclosure is preferably 500 or less, more preferably 400 or less, even more preferably 300 or less, and even more preferably 260 or less, and particularly preferably 200 or less, 100 or less, or 90 or less. The lower limit is, for example, 1 or more, preferably 10 or more. Preferred ranges include about 1 to 500, about 1 to 400, about 1 to 300, about 1 to 260, about 1 to 200, about 1 to 100, about 1 to 90, about 10 to 500, about 10 to 400, about 10 to 300, about 10 to 260, about 10 to 200, about 10 to 100, and about 10 to 90.

[0034] The degree of ethyl substitution (DS) of the low polymerization ethyl cellulose obtained by the method for producing low polymerization ethyl cellulose of the present disclosure is preferably 1.0 to 3.0, more preferably 1.5 to 3.0, even more preferably 2.0 to 3.0, and particularly preferably 2.4 to 3.0.

[0035] The number average molecular weight (Mn) of the low polymerization degree ethyl cellulose obtained by the method for producing low polymerization degree ethyl cellulose of the present disclosure is preferably 30,000 or less, more preferably 20,000 or less, even more preferably 15,000 or less, even more preferably 10,000 or less, and particularly preferably 7,300 or less. The lower limit is, for example, 1,000 or more, preferably 3,000 or more, and even more preferably 5,000 or more. Preferred ranges include about 1,000 to 30,000, about 1,000 to 20,000, about 1,000 to 15,000, about 3,000 to 30,000, about 3,000 to 20,000, about 3,000 to 15,000, about 5,000 to 30,000, about 5,000 to 20,000, and about 5,000 to 15,000.

[0036] The weight average molecular weight (Mw) of the low polymerization degree ethyl cellulose obtained by the method for producing low polymerization degree ethyl cellulose of the present disclosure is preferably 80,000 or less, more preferably 60,000 or less, even more preferably 50,000 or less, still more preferably 30,000 or less, and particularly preferably 20,000 or less. The lower limit is, for example, 1,000 or more, preferably 5,000 or more, and even more preferably 100 00 or more, and preferred ranges include about 1000 to 80000, about 1000 to 60000, about 1000 to 50000, about 1000 to 30000, about 5000 to 80000, about 5000 to 60000, about 5000 to 50000, about 5000 to 30000, about 10000 to 80000, about 10000 to 60000, about 10000 to 50000, and about 10000 to 30000.

[0037] The polydispersity (Mw / Mn) of the low polymerization ethyl cellulose obtained by the method for producing low polymerization ethyl cellulose according to the present disclosure is preferably 10 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 3.5 or less. The lower limit is, for example, 1 or more, preferably 2 or more. Preferred ranges include 1 to 10, 1 to 7, 1 to 5, 2 to 10, 2 to 7, and 2 to 5.

[0038] The reduced polymerization degree ethyl cellulose obtained by the method for producing reduced polymerization degree ethyl cellulose of the present disclosure, excluding molecules containing non-reducing terminal glucose residues in the raw ethyl cellulose (EC), has only a hydroxyl group (100% hydroxyl group) at the C4 position of the non-reducing terminal glucose residues of the remaining EC. In other words, when the raw EC is decomposed, it can be said that the newly generated non-reducing terminals, excluding the non-reducing terminals of the raw EC, have only a hydroxyl group (100% hydroxyl group). In this specification, the reduced polymerization degree ethyl cellulose is simply referred to as reduced polymerization degree ethyl cellulose in which the 4-position on the non-reducing terminal side of the cellulose is a hydroxyl group. On the other hand, the reduced polymerization degree ethyl cellulose of the present disclosure differs from conventional ethyl cellulose produced by depolymerizing pulp with alkali in, for example, whether the C4 position of the non-reducing terminal glucose residue is only a hydroxyl group (100% hydroxyl group) or a mixture of an ethoxy group and a hydroxyl group.

[0039] The method for reducing the degree of polymerization of ethyl cellulose according to the present disclosure is a method for reducing the degree of polymerization of the starting ethyl cellulose by ethanolysis of the starting ethyl cellulose in the presence of an acid catalyst and ethanol, and the specific method is as described above.

[0040] 2. Low-polymerization ethyl cellulose The present disclosure can provide ethyl cellulose having a number-average degree of polymerization (DPn) of 35 or less. The present disclosure can also provide ethyl cellulose having a weight-average degree of polymerization (DPw) of 90 or less. There are no particular limitations on the method for producing these ethyl celluloses, but they can be suitably produced by the method for producing low-polymerization ethyl cellulose of the present disclosure described above in "1. Method for producing low-polymerization ethyl cellulose."

[0041] The preferred number-average degree of polymerization (DPn), weight-average degree of polymerization (DPw), degree of ethyl substitution (DS), number-average molecular weight (Mn), weight-average molecular weight (Mw), and polydispersity (Mw / Mn) of the low-polymerization ethyl cellulose of the present disclosure are the same as those of the low-polymerization ethyl cellulose described above in "1. Method for producing low-polymerization ethyl cellulose," and therefore descriptions thereof are omitted.

[0042] As described above, the reduced polymerization degree ethyl cellulose obtained by the method for producing reduced polymerization degree ethyl cellulose of the present disclosure differs from conventional ethyl cellulose produced by depolymerizing pulp with alkali in, for example, whether the C4 position of the non-reducing end glucose residue is solely a hydroxyl group (100% hydroxyl group) or a mixture of an ethoxy group and a hydroxyl group. Therefore, the reduced polymerization degree ethyl cellulose of the present disclosure, excluding molecules containing non-reducing end glucose residues in the raw ethyl cellulose (EC), has solely a hydroxyl group (100% hydroxyl group) at the C4 position of the non-reducing end glucose residue of the remaining EC. In other words, when the raw EC is decomposed, the newly generated non-reducing ends, excluding the non-reducing ends of the raw EC, are solely hydroxyl groups (100% hydroxyl group). In this specification, the reduced polymerization degree ethyl cellulose is also simply referred to as a reduced polymerization degree ethyl cellulose having a hydroxyl group at the 4-position on the non-reducing end side of the cellulose.

[0043] Furthermore, the low-polymerization ethyl cellulose obtained by the method for producing low-polymerization ethyl cellulose of the present disclosure preferably exhibits liquid crystallinity. Therefore, the low-polymerization ethyl cellulose of the present disclosure preferably exhibits liquid crystallinity. The liquid crystallinity of ethyl cellulose means that it is evaluated as being levorotatory or dextrorotatory by <circular dichroism (CD) measurement> described in the Examples below.

[0044] A second method for producing low-polymerization ethyl cellulose may also be a method using cellulose as a raw material. In this case, low-polymerization ethyl cellulose is obtained by high-temperature, high-pressure treatment in the presence of an acid catalyst and ethanol. As the acid catalyst, a metal salt is preferred, and for example, an inorganic acid selected from sulfuric acid, phosphoric acid, and boric acid is preferred. These may also be used in the form of a neutralized salt, such as sodium phosphate, cesium phosphate, cesium sulfate, magnesium phosphate, aluminum phosphate, and aluminum borate.

[0045] The amount of these catalysts used is sufficient relative to the cellulose, and specifically, it is preferably about 1 to 30% by weight, more preferably 10 to 25% by weight, relative to the cellulose. These catalysts can be used alone or in combination of two or more.

[0046] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0047] (Comparative Examples 1-4) Commercially available ethyl cellulose (trade name: Ethyl cellulose manufactured by Tokyo Chemical Industry Co., Ltd.) was subjected to the evaluation described below. The ethyl cellulose of Comparative Example 1 was manufactured by Tokyo Chemical Industry Co., Ltd. under the product code E0290, the ethyl cellulose of Comparative Example 2 was manufactured by Tokyo Chemical Industry Co., Ltd. under the product code E0266, the ethyl cellulose of Comparative Example 3 was manufactured by Tokyo Chemical Industry Co., Ltd. under the product code E0072, and the ethyl cellulose of Comparative Example 4 was manufactured by Tokyo Chemical Industry Co., Ltd. under the product code E0265. Each ethyl cellulose was dissolved in acetone, precipitated in distilled water, dissolved again in acetone, and reprecipitated in n-hexane for purification. The ethyl celluloses of Comparative Examples 1 to 4 were not subjected to polymerization degree reduction, but for convenience, the evaluation results are listed in the section on low-polymerization ethyl cellulose in Table 1.

[0048] (Examples 1-6) The commercially available ethyl cellulose (trade name: Ethyl Cellulose manufactured by Tokyo Chemical Industry Co., Ltd.) used in Comparative Example 1 was used as the raw material ethyl cellulose and subjected to ethanololysis in the presence of an acid catalyst (p-toluenesulfonic acid (p-TsOH)) and ethanol (ethanol (ultra-dehydrated) manufactured by Wako Pure Chemical Industries, Ltd.). The ethyl cellulose was dissolved in acetone, precipitated in distilled water, dissolved again in acetone, and reprecipitated in n-hexane to purify the raw material ethyl cellulose, which was then subjected to ethanololysis. The reaction temperature was fixed at 60°C, and the acid catalyst The amount added was varied within the range of 3 to 15 equivalents / anhydroglucose unit (AGU) as shown in Table 1, and the reaction time was varied within the range of 2 to 6 hours as shown in Table 1. The reaction temperature was set and the reaction solution was stirred using a personal organic synthesis apparatus (Tokyo Rikakikai Co., Ltd., EYELA, PPM-5512), and a dedicated test tube (φ24, standard solution volume 12.5 mL) was used as the reaction vessel. 50 mg (0.216 mmol) of raw material ethyl cellulose was weighed into the reaction vessel and dried under vacuum at room temperature for 1 hour or more together with other laboratory equipment. The reaction was carried out under atmospheric pressure in a N2 atmosphere. The tube was then released and quickly sealed with a septum. 5 mL of ethanol was added at 25°C to dissolve the EC, and then a predetermined amount of p-TsOH was added and allowed to react at 60°C for a predetermined time. A NaOH / ethanol solution prepared by dissolving an equal amount of NaOH as p-TsOH in 3 mL of ethanol was added dropwise to neutralize the solution. The resulting white precipitate of sodium p-toluenesulfonate was separated by solution filtration (filter paper: Kiriyama hard filter paper No. 4), and the filtrate was concentrated using an evaporator. The other samples were dissolved in ethyl acetate and then washed with distilled water, and it was confirmed that the washing solution was neutral. After confirming the purity, the ethyl acetate was dehydrated with sodium sulfate. After removing the sodium sulfate by filtration of the solution, the ethyl acetate was removed using an evaporator. The obtained white powder was washed with n-hexane (to remove trace amounts of ethyl p-toluenesulfonate), yielding 40.0-48.5 mg (80-97 mol%) of low-polymerization ethyl cellulose. The low-polymerization ethyl celluloses of Examples 1 to 6 have only a hydroxyl group at the non-reducing end. More specifically, the low-polymerization ethyl cellulose of the present disclosure has only a hydroxyl group at the 4-position on the non-reducing end.

[0049] The commercially available ethyl cellulose of the comparative example and the low polymerization degree ethyl cellulose obtained in the examples were subjected to solubility measurement, circular dichroism (CD) measurement, and 1 The product was evaluated by HNMR measurement and GPC chromatographic measurement.

[0050] <Solubility Measurement> The ethyl cellulose of the comparative example and the low-polymerization ethyl cellulose obtained in the examples were used as samples. Each sample and chloroform were weighed into a 2 mL vial to give a concentrated solution with a sample concentration of 40 wt %, and the vial was sealed. The concentrated solution was visually inspected for homogeneity. If the solution was homogeneous, it was considered to be completely dissolved, and the solubility was described as "homogeneous." If the solution was not homogeneous due to residual polymer components, for example, it was described as "heterogeneous." If the solution was not homogeneous, "turning the sample tube upside down until the concentrated solution flows down from top to bottom under its own weight" was considered a single operation to promote dissolution (dissolution operation). This operation was repeated 0, 10, and 20 times, and then CD measurement was performed to evaluate the liquid crystallinity (solubility). If the CD measurement result showed a single peak, it was determined that the system was homogeneous, and the solubility was described as "homogeneous." If the CD measurement result did not show a single peak, it was determined that the system was heterogeneous, and the solubility was described as "heterogeneous." The results are shown in Table 1.

[0051] <Circular Dichroism (CD) Measurement> Commercially available ethyl cellulose for the comparative example and the low-polymerization ethyl cellulose obtained in the examples were used as samples. Each sample and chloroform were weighed into a 2 mL vial and sealed to form a concentrated solution with a sample concentration of 40 wt %. For circular dichroism (CD) measurements, a JASCO J-820DH circular dichroism spectrometer was used, and a JASCO PTC-423L Peltier thermostat was used for temperature control. The concentrated solution to be measured was prepared by tilting the vial in advance to allow the concentrated solution to flow onto the wall and then leaving it in a refrigerator (up to 5°C) for at least two days. The liquid crystal sample was left to stand at the measurement temperature for at least 20 minutes before the measurement. The measurement result was the maximum reflection wavelength λmax at which the reflection wavelength became single. Furthermore, the measurement results were used to determine whether the sample was levorotatory (left) or dextrorotatory (right). The results are shown in Table 1.

[0052] < 1H NMR Measurement> For the commercially available ethyl cellulose of the comparative example and the low polymerization degree ethyl cellulose obtained in the example, 1 H NMR measurement was carried out to determine the degree of ethyl substitution (DS). The results are shown in Table 1. Furthermore, since no peaks derived from aromatic compounds appeared in the vicinity of 7.0-8.0 ppm in the spectrum of the low polymerization degree ethyl cellulose obtained in each Example, it was confirmed that tosyl groups derived from p-toluenesulfonic acid were not introduced into the cellulose chain of the ethyl cellulose. 1 The HNMR measurement conditions were as follows: The sample was dissolved in deuterated chloroform and measured using an INOVA 300 NMR manufactured by Varian. The obtained spectrum was expressed in ppm units based on the internal standard substance TMS. Data processing was performed using Bruker's TopSpin ver. 4.1.4. Sample concentration: 5-10 mg / 0.75 mL, number of accumulations: 16, relaxation time: 3.5 seconds

[0053] <GPC Chromatography Measurement> GPC chromatography measurement was performed on the commercially available ethyl cellulose of the comparative examples and the low-polymerization ethyl cellulose obtained in the examples, and the number-average molecular weight Mn, weight-average molecular weight Mw, polydispersity index Mw / Mn, DPn, degree of polymerization DPn, and degree of polymerization DPw were measured and calculated. The results are shown in Table 1. The measurement conditions for GPC chromatography were as follows. A sample was dissolved in THF (stabilizer: BHT) to a concentration of 0.5 mg / mL, and GPC measurement was performed using a Shimadzu LC-20 system (manufactured by Shimadzu Corporation). The measurement conditions were as follows: Flow rate: 0.2 mL / min Detector: RI detector Column temperature: 40°C Measurement time: 60 minutes Column: The following four columns (all manufactured by Tosoh Corporation) were used in conjunction. TSKgel Guardcolumn Super HZ-L (column size 4.6 mm I.D. x 15 cm) TSKgel Super HZ1000 (particle size 3 μm, column size 4.6 mm I.D. x 15 cm, exclusion limit molecular weight (polystyrene) 1,000) TSKgel Super HZ2000 (particle size 3 μm, column size 4.6 mm I.D. x 15 cm, exclusion limit molecular weight (polystyrene) 10,000) TSKgel Super HZ3000 (particle size 3 μm, column size 4.6 mm I.D. x 15 cm, exclusion limit molecular weight (polystyrene) 60,000)

[0054]

[0055] In Table 1, "-" indicates that the test was not performed. Also, in Table 1, "nd" indicates that there was no CD peak (i.e., there was no single peak).

[0056] In the above-mentioned solubility test, the low polymerization degree ethyl celluloses obtained in Examples 1 to 6 were confirmed to have uniform liquid crystallinity (solubility) by CD measurement after at least one dissolution procedure was repeated 20 times. That is, the low polymerization degree ethyl celluloses obtained in Examples 1 to 6 have excellent solubility.

[0057] (Example 7) 0.50 g of powdered cellulose (degree of polymerization 600) was added to a small autoclave (container volume 30 ml), and then 0.1 g of sodium phosphate and 10 ml of ethanol were added. The atmosphere was replaced with nitrogen and degassed. While stirring, the temperature was raised to 220°C in a high-temperature oil bath. The pressure inside the vessel initially indicated 2 MPa. After stirring for 10 hours, the mixture was cooled to room temperature. After distilling off unreacted ethanol, the mixture was washed with hydrous isopropanol (water content 15%) and acetone, and then dried under reduced pressure to obtain low-polymerization ethyl cellulose as a light brown solid. 1 From HNMR analysis, the degree of substitution of ethyl groups in ethyl cellulose was 2.5 per glucose unit.

Claims

1. A step of preparing raw material ethyl cellulose, and a step of subjecting the raw material ethyl cellulose to ethanolysis in the presence of an acid catalyst and ethanol to obtain ethyl cellulose with a reduced degree of polymerization, in which the degree of polymerization of the raw material ethyl cellulose is reduced. A method for producing ethyl cellulose with a reduced degree of polymerization, comprising the steps of:

2. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1, wherein the number average degree of polymerization (DPn) of the raw material ethyl cellulose is more than 180.

3. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1 or 2, wherein the weight average degree of polymerization (DPw) of the raw material ethyl cellulose is more than 500.

4. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1 or 2, wherein the ethyl substitution degree (DS) of the raw material ethyl cellulose is 1.0 to 3.

0.

5. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1, wherein the number average degree of polymerization (DPn) of the ethyl cellulose with a reduced degree of polymerization is 100 or less.

6. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1 or 2, wherein the weight average degree of polymerization (DPw) of the ethyl cellulose with a reduced degree of polymerization is 260 or less.

7. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1 or 2, wherein the ethyl substitution degree (DS) of the ethyl cellulose with a reduced degree of polymerization is 1.0 to 3.

0.

8. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1 or 2, wherein the number average molecular weight (Mn) of the ethyl cellulose with a reduced degree of polymerization is 30,000 or less.

9. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1 or 2, wherein the weight average molecular weight (Mw) of the ethyl cellulose with a reduced degree of polymerization is 80,000 or less.

10. The method for producing ethyl cellulose with a reduced degree of polymerization according to claim 1 or 2, wherein the polydispersity (Mw / Mn) of the ethyl cellulose with a reduced degree of polymerization is 10 or less.

11. Ethyl cellulose having a number average degree of polymerization (DPn) of 35 or less.

12. The ethyl cellulose according to claim 11, having a weight average degree of polymerization (DPw) of 90 or less.

13. The ethyl cellulose according to claim 11 or 12, having a number average molecular weight (Mn) of 7,300 or less.

14. The ethyl cellulose according to claim 11 or 12, having a weight average molecular weight (Mw) of 20,000 or less.

15. The ethyl cellulose according to claim 11 or 12, wherein the C4 position of the non-reducing terminal glucose residue of the remaining raw material ethyl cellulose excluding the molecule containing the non-reducing terminal glucose residue of the raw material ethyl cellulose has only a hydroxyl group.

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