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Method for producing low-substituted hydroxypropylcellulose

A hydroxypropyl cellulose, low-substituted technology, applied in the field of producing low-substituted hydroxypropyl cellulose, can solve difficult, expensive and other problems, and achieve the effect of avoiding explosions

Active Publication Date: 2012-04-04
SHIN ETSU CHEM IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since these methods use expensive reagents, leave reagents in the resulting product, or require special equipment, it is considered difficult to realize these methods industrially

Method used

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  • Method for producing low-substituted hydroxypropylcellulose

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] A reactor with a volume of 144 liters and equipped with an internal stirring structure was filled with 8 kg of powdery slurry. Under stirring, 6.32 kg of 25% by weight aqueous sodium hydroxide solution was added to the reactor for 6 minutes, followed by stirring for 14 minutes to prepare alkali cellulose.

[0034] The reactor was then purged with nitrogen. After purging with nitrogen, 1.48 kg of propylene oxide was added while maintaining the reactor at 60° C. and an etherification reaction was performed for 75 minutes.

[0035] After the etherification reaction, the measured pressure in the reactor dropped to -0.080 MPa under stirring conditions. Then, the pressure in the reactor was increased to -0.0145 MPa with nitrogen. Once the air supply valve was opened to increase the pressure to 0 MPa, the vacuum valve and the air supply valve of the reactor were closed. Through this operation, the oxygen concentration in the reactor was adjusted to 3.0% by volume and depoly...

Embodiment 2

[0039] A reactor with a volume of 144 liters and equipped with an internal stirring structure was filled with 8 kg of powdery slurry. Under stirring, 6.32 kg of 35% by weight aqueous sodium hydroxide solution was added to the reactor for 6 minutes, followed by stirring for 14 minutes to prepare alkali cellulose.

[0040] The reactor was then purged with nitrogen. After purging with nitrogen, 1.48 kg of propylene oxide was added while maintaining the reactor at 60° C. and an etherification reaction was performed for 75 minutes.

[0041] After the etherification reaction, the measured pressure in the reactor dropped to -0.080 MPa under stirring conditions. Then, the pressure in the reactor was increased to -0.024 MPa with nitrogen. Once the air supply valve was opened to increase the pressure to 0 MPa, the vacuum valve and the air supply valve of the reactor were closed. Through this operation, the oxygen concentration in the reactor was adjusted to 5.0% by volume and depolym...

Embodiment 3

[0044] A reactor with a volume of 144 liters and equipped with an internal stirring structure was filled with 8 kg of powdery slurry. Under stirring, 6.32 kg of 35% by weight aqueous sodium hydroxide solution was added for 6 minutes, followed by stirring for 14 minutes to prepare alkali cellulose.

[0045] The reactor was then purged with nitrogen. After purging with nitrogen, 1.48 kg of propylene oxide was added while maintaining the reactor at 60° C. and an etherification reaction was performed for 75 minutes.

[0046] After the etherification reaction, the measured pressure in the reactor dropped to -0.080 MPa under stirring conditions. Then, the pressure in the reactor was increased to -0.0336 MPa with nitrogen. Once the air supply valve was opened to increase the pressure to 0 MPa, the vacuum valve and the air supply valve of the reactor were closed. Through this operation, the oxygen concentration in the reactor was adjusted to 6.8% by volume and depolymerization of t...

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Abstract

Provided is a method for producing low-substituted hydroxypropylcellulose in which depolymerization capable of achieving a target viscosity in a short time is carried out safely after an etherification reaction step. More specifically, provided is a method for producing low-substituted hydroxypropylcellulose having a degree of hydroxypropoxy substitution of from 9.5 to 16.0% by weight, comprising at least a step of reacting alkali cellulose with an etherifying agent and a step of carrying out depolymerization after the reaction.

Description

technical field [0001] The present invention relates to a method for producing cellulose ethers used in the fields of chemistry and medicine. Background technique [0002] Examples of depolymerization methods for reducing the viscosity of water-soluble cellulose ethers include methods using ozone or volatile acids such as hydrogen peroxide or hydrogen halide. However, since these methods use expensive reagents, leave reagents in the resulting product, or require special equipment, it is considered difficult to realize these methods industrially. [0003] Unexamined Japanese Patent Application Publication No. 61-264001 proposes a method of adjusting the amount of oxygen in a reactor for producing alkali cellulose. Since the degree of polymerization of cellulose is reduced by the reaction between oxygen and cellulose (depolymerization reaction) in the presence of alkali, a cellulose ether having a lower viscosity can be obtained when the amount of oxygen is larger. This meth...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B11/08
CPCC08B11/08C08B11/20C08B1/08C08B1/00C08B15/00C08B15/02
Inventor 北村彰铃木崇裕成田光男
Owner SHIN ETSU CHEM IND CO LTD
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