N-vinylpyrrolidone with a purity of 99.99% was used as the raw material, purified water was used, and sulfur dioxide was used as an initiator, wherein the sulfur dioxide existed in the form of a 10% sulfur dioxide solution.
First, pure water and N-vinylpyrrolidone were added to the polymerization kettle to obtain a solution of N-vinylpyrrolidone with a concentration of 33.3%. Under the condition of 40°C, stirring was carried out. After stirring evenly, 0.54% by weight of sulfur dioxide was added as an initiator. , and then 0.2% by weight of catalyst was added, and the polymerization reaction occurred under these conditions.
The temperature of the polymerization reaction was controlled at 40°C, and the pH value of the solution was adjusted to 9 by dripping concentrated ammonia. After fully stirring, the reaction time was 6.5 hours, and then sampling and analysis were performed to detect the content of N-vinylpyrrolidone. If the content of N-vinylpyrrolidone is less than 20PPm, the reaction is completed. If the content is greater than 20PPm, continue the reaction until the content of N-vinylpyrrolidone is less than 20PPm. The sampling detection adopts high pressure liquid chromatography analysis method.
Under stirring conditions, the Pvp Polyvinylpyrrolidone kettle was cooled to room temperature, and a colorless transparent liquid was obtained in the kettle, and an aqueous solution of Pvp Polyvinylpyrrolidone with a K value of 30 was obtained. The qualified polymer solution is directly introduced into a spray drying system or a drum drying system for drying, the pressure is controlled at -1000pa, and the drying temperature is 160°C, and white Pvp Polyvinylpyrrolidone powder is obtained after drying.
A preparation method of Pvp Polyvinylpyrrolidone is prepared according to the following steps:
(a) 0.51 mmol of ferrous chloride and 0.2 g of crospovidone were added to the flask, 40 mL of ethanol was added, and stirred uniformly under nitrogen protection;
(b) 160mmol of N-vinylpyrrolidone was added to the flask and stirred uniformly;
(c) adding 0.8mmol methyl 2-bromopropionate to the flask, stirring at 40° C. to carry out a polymerization reaction, reacting for 7 hours, and filtering to obtain a polyvinylpyrrolidone crude material;
(d) 1 g of crospovidone is added to the Pvp Polyvinylpyrrolidone crude material and mixed, after stirring, filtering, and after the solvent is distilled off under reduced pressure, then washed with anhydrous ether to obtain polyvinylpyrrolidone;
Wherein, the adopted crospovidone has a particle size of 5 μm and a bulk density of 0.4 g/mL.
A kind of preparation method of high molecular weight Pvp Polyvinylpyrrolidone, its steps are as follows:
First, add 750kg of pure water into the polymerization kettle, adjust the pH value to make the pH value > 7.0; add 250kg of NVP to the pure water under stirring, heat up to about 50-55°C under the protection of nitrogen, remove it with ultrasonic waves Oxygen for 30 minutes; when the polymerization kettle temperature reached 70 ° C, 2.5kg of azobisisobutylimidazoline hydrochloride was added to the reaction kettle, and a polymerization reaction occurred under this condition; after 6 hours of constant temperature of reaction, start sampling Analyze and detect the NVP content in the sample. When the NVP content is less than 0.002%, lower the temperature of the reaction system to below 40 degrees, and end the reaction to obtain a polymer solution with a K value of about 55; this polymer solution is dried by spray drying. , a white powdery product was obtained.