Preparation technology of hydroxypropyl methylcellulose ether (HPMC)

Abstract

The invention relates to a preparation technology of hydroxypropyl methylcellulose ether (HPMC), belonging to the field of the fine chemical industry. The preparation technology comprises the following steps of: 1) independent alkalization: firstly adding 7-8 parts of caustic soda flakes into a diluting agent system in an alkalization kettle; then heating to increase temperature to 70-80DEG C and then decreasing temperature to 10-25DEG C; and finally adding 8-9 parts of refined cotton into the alkalization kettle and keeping the temperature to be constant at 10-25DEG C for 2-3 hours; and 2) two-step etherification: firstly, feeding alkalized materials in the alkalization kettle into an etherification kettle; then adding etherifying agent and increasing temperature to 53-58DEG C for first-step etherification; increasing temperature to 81-87DEG C for second-step etherification; and finally a proper amount of acetic acid into a reactor for neutralization to obtain the HPMC. Due to the preparation technology, the reaction uniformity is obviously improved; and compared with products which are obtained by adopting the traditional production method, the water retention rate of the HPMC prepared by adopting the technology is improved by more than 20 percent and the viscosity is improved by more than 30 percent.

Description

technical field

[0001] The invention relates to a production process of hydroxypropyl methylcellulose ether (HPMC), which belongs to the field of fine chemicals. Background technique

[0002] my country's cellulose derivatives industry started in the 1960s and has a history of more than 40 years. The development of HMPC in my country was relatively late. Wuxi Research Institute of Chemical Industry first carried out production process research in the 1970s. It was successfully prepared in the former Luzhou Chemical Plant in 1982, and the first production line was established in 1987. Compared with foreign countries, the number of cellulose ether manufacturers in my country is too large, the production capacity is greater than the demand, the scale and technical level of enterprises are quite different, there is a lack of investment in scientific research, and the progress of product updates is slow. With the rapid development of the fine chemical industry, people have highe...

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