Production process of cross-linked polyvinylpyrrolidone
Cross-linked polyvinylpyrrolidone is a water-insoluble homopolymer cross-linked by N-vinylpyrrolidone, with a molecular formula of (C6H9NO)n, where n represents the average number of 1-vinyl-2-pyrrolidone chain segments. Calculated as anhydrous, the nitrogen content (N) should be 11.0%-12.8%.
Cross-linked polyvinylpyrrolidone is mainly used in the pharmaceutical industry. As one of the three major new pharmaceutical excipients advocated internationally, it is mainly used as a disintegrant and filler in medicines, a super decomposer in tablets, and is used to disintegrate tablets and improve the release rate of active ingredients in tablets, capsules and pills. Insoluble cross-linked polyvinylpyrrolidone is a swellable polymer with a wide range of applications. Because they have a decomposing effect on tablets, can hydrophilize various insoluble drugs, can stabilize various suspending agents, and have the ability to form complexes and adsorption, they can be used as pharmaceutical adjuvants.
The preparation of cross-linked polyvinylpyrrolidone usually adopts the self-crosslinking polymerization method of N-vinylpyrrolidone. In this method, in the presence of alkali metal hydroxide, N-vinylpyrrolidone is heated to above 100°C to react with each other, and self-crosslink to obtain cross-linked polyvinylpyrrolidone, but the purity of the obtained cross-linked polyvinylpyrrolidone is not high.
In view of the wide range of effects of cross-linked polyvinylpyrrolidone, it is urgent to develop a new process for the synthesis of cross-linked polyvinylpyrrolidone. By controlling the polymerization reaction conditions, the reactants can fully react, and then obtain cross-linked polyvinylpyrrolidone with higher purity.
Step I: Dissolve anhydrous sodium sulfate, anhydrous disodium hydrogen phosphate, and polyvinylpyrrolidone K30 with purified water;
Add N-vinylpyrrolidone to the solution of step I, and fill it with nitrogen as a reaction protective gas;
Wherein, the mass ratio of anhydrous sodium sulfate, anhydrous disodium hydrogen phosphate, and polyvinylpyrrolidone K30 is 5:5:1-5:7:3, and the mass volume ratio of polyvinylpyrrolidone K30 to purified water is 1:100-1:120.
The present invention uses safe and cheap hydrogen peroxide as a catalyst, and uses the free radicals generated during its redox reaction to initiate polymerization. Hydrogen peroxide decomposes into water and oxygen, which is safe and non-toxic. The dispersant used in the present invention is a water-soluble organic polymer polyvinyl pyrrolidone K30, which can prepare cross-linked polyvinylpyrrolidone with uniform particle size and moderate apparent density.
The present invention continuously adds hydrogen peroxide catalyst, which can reduce the generation of impurities such as peroxides, is simpler to operate, and the cross-linked polyvinylpyrrolidone obtained has higher purity.