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Production Technology of hydroxypropyl Methyl Cellulose
1. Production method(Huibai reagent: http://www.hnhbsj.com)
Hydroxypropyl methyl cellulose (HPC) is generally produced from cotton wool. The production process includes three steps: alkali treatment, hydroxypropylation and methylation. Cotton wool is usually treated with 50% to obtain cellulose, propylene oxide for hydroxypropylation, and methylation with methylene methane. The technical indexes of evaluating hydroxypropyl methyl cellulose are methyl substitution degree, etherification efficiency, polymerization degree and viscosity.
At present, the production methods of hydroxypropyl methyl cellulose are mainly divided into one-step etherification method and stepwise etherification method according to different operating procedures, and these two processes can be carried out under different reaction conditions.
(l) step etherification method
1. Firstly, the powder cotton velvet reacted with propylene oxide in nitrogen for 3 h, and the reaction temperature was 30 ~ 60 ℃. Then the sh, reaction temperature was 35 ~ 80 ℃, and the degree of substitution of the compacted propyl group was 23. 5%.
(2) the alkali-treated cotton wool reacted with propylene oxide in the presence of halogenated hydrocarbons, and then, in the presence of sodium nitroxide, a methanethane was obtained. The conversion rates of propylene oxide and methane were 42.6% and 41.6%, respectively.
(2) One-step etherification
1. When the mixture of powdered cotton velvet and 50%Na0H aqueous solution is 60 ℃, the mixture gas of 52% methyl ether, 43% chloroform and 5% propylene oxide is continuously passed through under the pressure of 2.26X10 at the fourth power MPa of the reactor. Add 50%NaOH solution again and mix it. The methane continues to flow into the atmosphere and reacts at 80 ℃. The degree of substitution of methyl and hydroxypropyl methyl cellulose was 20.0 and 25.4 respectively, and the insoluble substance was less than 0.05. The conversion of methane and propylene oxide was 53.8% and 42.6% respectively.
(2) 50%NaOH aqueous solution was sprayed on powdered cotton velvet and heated to 85 ℃, adding propylene oxide, chloroform and heating until the reaction was complete. The degree of methyl substitution of hydroxypropyl methylcellulose was 17.0 and the degree of substitution of hydroxypropyl methylcellulose was 24.8. The conversion of methyl and propylene oxide was 37.8 and 26.2 respectively.
2. Production process(Huibai reagent: http://www.hnhbsj.com)
As a typical Nonionic cellulose ether, hydroxypropyl methyl cellulose (HPC) is usually produced by intermittent method and continuous method. Batch method is to treat cotton velvet after alkali treatment, then press, comminute, ripen, and then etherification reaction with etherifying agent in autoclave, feed into single kettle and discharge from single kettle. The continuous process is that cotton wool is not pressed, crushed and cooked in the process of alkali treatment. Instead, it is carried out in a set of continuous equipment, and etherification reaction, continuous feed and continuous discharge are carried out in a high pressure pipeline reactor. According to different requirements, there can be different viscosity of various brands for selection.
The material comes from the network.
For more information on biochemical reagents, check out Huibai Reagent's official website: http://www.hnhbsj.com
(all contents of this website are marked as "Huibai Reagent", copyright is owned by Huibai Reagent. Any media, website or individual shall not be reproduced without authorization, otherwise, legal liability will be investigated. Authorization to reprint should be marked "source: Huibai Reagent". This website indicates the source is other media content is reprinted, reprint only for the viewpoint sharing, the copyright belongs to the original author all, if has the infringement copyright, please contact us in time.
Hydroxypropyl methyl cellulose (HPC) is generally produced from cotton wool. The production process includes three steps: alkali treatment, hydroxypropylation and methylation. Cotton wool is usually treated with 50% to obtain cellulose, propylene oxide for hydroxypropylation, and methylation with methylene methane. The technical indexes of evaluating hydroxypropyl methyl cellulose are methyl substitution degree, etherification efficiency, polymerization degree and viscosity.
At present, the production methods of hydroxypropyl methyl cellulose are mainly divided into one-step etherification method and stepwise etherification method according to different operating procedures, and these two processes can be carried out under different reaction conditions.
(l) step etherification method
1. Firstly, the powder cotton velvet reacted with propylene oxide in nitrogen for 3 h, and the reaction temperature was 30 ~ 60 ℃. Then the sh, reaction temperature was 35 ~ 80 ℃, and the degree of substitution of the compacted propyl group was 23. 5%.
(2) the alkali-treated cotton wool reacted with propylene oxide in the presence of halogenated hydrocarbons, and then, in the presence of sodium nitroxide, a methanethane was obtained. The conversion rates of propylene oxide and methane were 42.6% and 41.6%, respectively.
(2) One-step etherification
1. When the mixture of powdered cotton velvet and 50%Na0H aqueous solution is 60 ℃, the mixture gas of 52% methyl ether, 43% chloroform and 5% propylene oxide is continuously passed through under the pressure of 2.26X10 at the fourth power MPa of the reactor. Add 50%NaOH solution again and mix it. The methane continues to flow into the atmosphere and reacts at 80 ℃. The degree of substitution of methyl and hydroxypropyl methyl cellulose was 20.0 and 25.4 respectively, and the insoluble substance was less than 0.05. The conversion of methane and propylene oxide was 53.8% and 42.6% respectively.
(2) 50%NaOH aqueous solution was sprayed on powdered cotton velvet and heated to 85 ℃, adding propylene oxide, chloroform and heating until the reaction was complete. The degree of methyl substitution of hydroxypropyl methylcellulose was 17.0 and the degree of substitution of hydroxypropyl methylcellulose was 24.8. The conversion of methyl and propylene oxide was 37.8 and 26.2 respectively.
2. Production process(Huibai reagent: http://www.hnhbsj.com)
As a typical Nonionic cellulose ether, hydroxypropyl methyl cellulose (HPC) is usually produced by intermittent method and continuous method. Batch method is to treat cotton velvet after alkali treatment, then press, comminute, ripen, and then etherification reaction with etherifying agent in autoclave, feed into single kettle and discharge from single kettle. The continuous process is that cotton wool is not pressed, crushed and cooked in the process of alkali treatment. Instead, it is carried out in a set of continuous equipment, and etherification reaction, continuous feed and continuous discharge are carried out in a high pressure pipeline reactor. According to different requirements, there can be different viscosity of various brands for selection.
The material comes from the network.
For more information on biochemical reagents, check out Huibai Reagent's official website: http://www.hnhbsj.com
(all contents of this website are marked as "Huibai Reagent", copyright is owned by Huibai Reagent. Any media, website or individual shall not be reproduced without authorization, otherwise, legal liability will be investigated. Authorization to reprint should be marked "source: Huibai Reagent". This website indicates the source is other media content is reprinted, reprint only for the viewpoint sharing, the copyright belongs to the original author all, if has the infringement copyright, please contact us in time.
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