The activation energy of the reaction in this step is reduced, while the fluidity of the reaction mixture is improved, and the defect of low yield of methylation reaction in the original process is solved. In the example, through the research and application of the solid phase reactor, hydroxypropyl methylcellulose phthalate particles are formed.
One is to become a highly efficient auxiliary, improve the reaction yield, and control the generation of side reactions,
Second, as a catalyst, HPMC is used as an efficient catalyst to improve the purity of reactants and the reaction yield, so that the reaction yield can be increased to 98%. The utilization rate of raw materials is increased to 95% through the use of hydroxypropyl methyl cellulose as auxiliary agent, which guarantees the preparation of hydroxypropyl methyl cellulose phthalate and prevents agglomeration between particles in the post-treatment process.
The third is to solve the problem of low yield of the original process. A representative experiment is to reduce the unit consumption of raw cotton fiber from 1.05t/t of the original process to 0.94t/t during the phthalic acid reaction., In the process of hydroxypropylation reaction, phthalic anhydride reaction residues, free phthalic acid and residual acetic acid solvent can be removed. The yield of this step was increased to 95%.