JPH01123801A - Production of cellulose ether - Google Patents

Abstract

PURPOSE:To produce economically a cellulose ether of a uniform distribution of substituents, by treating cellulose with an alkali to form an alkali cellulose in a process for producing a cellulose ether, and further carrying out a specified treatment on this alkali cellulose with an epoxy compound. CONSTITUTION:Cellulose (e.g., wood pulp) is dispersed in 5-30pts.wt., per pt.wt. cellulose, lower aliphatic alcohol (e.g., t-butanol)/water solvent containing 1.0-3.0mol. of an alkali (e.g., NaOH) per mol of glucose residues of cellulose in a nitrogen stream to give an alkali cellulose, which is reacted with 2.5-5mol., per glucose residue, of an epoxy compound (e.g., ethylene oxide) in the presence of an alkali and further reacted with 0.1-0.9mol., per mol of the alkali metal hydroxide used, of a compound (e.g., 2-chloroethanol) which can react with an alkali to form an epoxy compound.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing cellulose ether with a uniform distribution of substituents.

(Prior art and problems) Cellulose ether is an industrially important compound as a water-soluble polymer, but cellulose ether, which has a uniform distribution of substituents, is enzyme-resistant and hard to rot, so it is used in various applications including paints. It is used for a purpose.

Conventionally, as a method for obtaining such cellulose ether, as is well known in this field, cellulose ether having a degree of substitution of about 1.0 is first subjected to W! ! ! left behind,
Using the obtained cellulose ether as a raw material, perform the etherification reaction again at a low alkali concentration, or add acid during the etherification reaction to reduce the alkali concentration in the reaction system, and then add an etherification agent to the reaction system. However, these methods require a long and complicated manufacturing process, and therefore this type of cellulose ether is expensive in terms of cost. I had no choice but to do so.

The present inventors have completed the present invention as a result of intensive studies on a method for efficiently producing cellulose ether having a uniform substituent distribution in a shorter process.

(Means for Solving the Problems) That is, the present invention provides a method for producing cellulose ether by treating cellulose with an alkali to obtain alkali cellulose, and then reacting the alkali cellulose with an epoxy compound in the presence of an alkali. This method of producing cellulose ether is characterized by adding a compound that reacts with an alkali in the reaction system to generate an epoxy compound.

As the raw material cellulose of the present invention, any of wood bulbs, linters, etc. can be used. There are two methods for producing cellulose ether: a kneader method and a slurry method. Although the present invention can be applied to either method, it is preferable to use the slurry method. In addition, the solvent used in the slurry method is usually Various organic solvents to aqueous solvents can be used, but lower aliphatic alcohol-aqueous solvents such as t-butanol and isopropanol are particularly preferred.The amount of solvent to be used is from 5 times the weight of the cellulose used. It can be used in a range of 30 times.

The alkali used in the present invention may be any alkali that produces so-called alkali cellulose, and includes alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, but sodium hydroxide is usually used. It will be done. The amount used is determined by the amount of gluco of cellulose used.
It is preferable to use 1.0 to 3.0 molar equivalents, preferably 162 to 2.0 molar equivalents, per mole of -s residue.

Examples of the epoxy compound to be reacted with the alkali cellulose after the alcelization reaction include alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, and derivatives thereof. The amount of the epoxy compound to be reacted depends on the degree of substitution of the target cellulose ether, but it is per glucose residue of the cellulose used.2.
A range of 5 to 5 molar equivalents can be used.

In the present invention, the compound added to the reaction system during the etherification reaction is a compound that reacts with an alkali in the reaction system to generate an epoxy compound. For example, as a compound that generates ethylene oxide, 2-chloroethanol, ethylene Fatty acid esters of 2-chloroethyl alcohol such as glycol monoacetate, ethylene glycol diacetate, 2-chloroethyl acetic acid, and sulfonic acid esters of 2-chloroethyl alcohol are used. The amount used should not be greater than the alkali used, but it can be used within a range of 0.9 molar equivalent from Oll of the alkali metal hydroxide used. Although it is not necessary to lower the temperature of the reaction system during addition, it may be added after cooling the reaction system.

(Effect of the invention) In the conventional method, it is difficult to maintain a high concentration in the reaction system due to the low boiling point of the epoxy compound such as ethylene oxide, which is an etherification agent. Since the temperature of the reaction system had to be lowered, complicated steps were required in order to obtain a cellulose ether having a degree of substitution of 2.0 or more and a uniform substituent distribution.

In the method of the present invention, cellulose is treated with an alkali to obtain alkali cellulose, and then an epoxy compound is added and the reaction system is heated to perform an etherification reaction. By adding a compound that generates an epoxy compound and continuing the reaction, the alkali concentration in the system is reduced during the etherification reaction, and the concentration of the etherification agent in the system is increased without lowering the temperature of the reaction system. This is an extremely effective method that can accelerate the reaction rate.

According to the method of the present invention, the reaction time can be significantly shortened, and cellulose ether with a uniform distribution of substituents can be economically advantageously produced.

(Example) The present invention will be described below with reference to specific examples, but the present invention is not limited to these specific examples.

Example 1 85.1 g of wood pulp (6.0% moisture) was mixed with 990 g of 89% t-butanol containing 25.7 g of sodium hydroxide.
The mixture was dispersed in a stream of nitrogen. After stirring at 15°C for 2 hours, ethylene oxide 86.9. and heated to 55°C. After reacting for 1 hour, add 2-chloroethanol89.
Slowly drop 8 g. The reaction was carried out at 55°C for 2 hours and then at 70°C for 1 hour. After cooling the reaction system, nitric acid was added to make it neutral. After filtering, 80% acetone 80
The plate was washed twice with 0 all, and further washed with 100% acetone. The molar substitution degree (88) of the obtained droxyethyl cellulose was 2.45, the moisture content was 6%, and the yield was 140 g.
Met. The viscosity of the 2% aqueous solution was measured with a B-type viscometer and was found to be 4020 cps. Further, when the transparency was visually measured, it was found to be 600 W or more in a 2% aqueous solution. Furthermore, this hydroxyethyl cellulose was acid-hydrolyzed, reduced, and then methylated and analyzed by gas chromatography to examine the substituent distribution. As a result, glucose residues with a degree of substitution of 1 to 6 were as shown in the table.

Comparative Example In Example 1, the reaction was carried out without adding 2-chloroethanol. i.e. wood pulp (moisture 6.0%)
85.1. 89% containing 25.7° of sodium hydroxide
It was dispersed in 990 g of t-butanol under a nitrogen stream. 1
After stirring for 2 hours at 5°C, ethylene oxide 89.3. and heated to 55°C.

The reaction system, which was reacted for 3 hours and further reacted at 70° C. for 1 hour, was cooled and made neutral by adding nitric acid. After filtering 8
Wash twice with 0% acetone 800:1, then 100%
After washing with acetone, the resulting droxyethyl cellulose had an MS of 2.13, a moisture content of 4.1%, and a yield of 131 g. When the viscosity of a 2% aqueous solution was measured using a B-type viscometer, the result was 3.
It was 720 cps. Further, the transparency was visually measured and found to be 515++ m for a 2% aqueous solution. Furthermore, this hydroxyethyl cellulose was acid-hydrolyzed, reduced, and then methylated and analyzed by gas chromatography to examine the substituent distribution. As a result, glucose residues with a degree of substitution of 1 to 6 were as shown in the table.

Example 2 Wood pulp (moisture 6°0%) 85.1. was dispersed in 990 g of 89% t-butanol containing 25.7 g of sodium hydroxide under a nitrogen stream. After stirring at 15°C for 2 hours,
Add 86.9 g of ethylene oxide and heat to 55°C. After reacting for 1 hour, 2-chloroethyl acetate 3
Slowly drop 0.2 g.

The reaction was carried out at 55°C for 2 hours and then at 70°C for 1 hour.
After cooling the reaction system, nitric acid was added to make it neutral.

After filtration, it was washed twice with 800 ml of 80% acetone, and further washed with 100% acetone. The obtained droxyethylcellulose was 882.50% and the water content was 5.1%.
The yield was 142 tons. The viscosity of the 2% aqueous solution was measured with a B-type viscometer and found to be 3920 cps. In addition, when the transparency was visually measured, it was 620n with a 2% aqueous solution.
It was more than wa. Furthermore, this hydroxyethylcellulose was acid-hydrolyzed, reduced, methylated, and analyzed by gas chromatography to examine the substituent distribution.
Glucose residues with a degree of substitution of 1 to 6 were as shown in the table.

Example 3 85.1 g of wood pulp (6.0% moisture) was dispersed in 89% t-butanol containing 25.7 g of sodium hydroxide under a nitrogen stream. After stirring for 2 hours at 15°C, ethylene oxide 86.9. and heated to 55°C. After reacting for 1 hour, ethylene glycol diacetate 36.0
g was added slowly. 2 hours at 55°C, then 7
After cooling the 0 reaction system, which was reacted at 0° C. for 1 hour, nitric acid was added to make it neutral. After filtering, 80% acetone 800
ml twice and further washed with 100% acetone. The obtained hydroxyethylcellulose was 882.6,
The yield was 147 g with a moisture content of 7.0%. 2 with B type viscometer
% aqueous solution viscosity was measured and found to be 3770 cps. Further, when the transparency was visually measured, it was 600 degrees or higher in a 2% aqueous solution. Furthermore, the droxyethyl cellulose was acid-hydrolyzed, reduced, and then methylated and analyzed by gas chromatography to examine the substituent distribution. As a result, glucose residues with a degree of substitution of 1 to 6 were as shown in the table.

Claims (1)

[Claims] A compound that reacts with the alkali in the reaction system to generate an epoxy compound in a method of producing cellulose ether by treating cellulose with an alkali to obtain alkali cellulose and then reacting the alkali cellulose with an epoxy compound in the presence of an alkali. A method for producing cellulose ether, characterized by adding.