SU111666A1 - The method of producing copolymers - Google Patents

Description

A known method for producing copolymers based on the reaction products of vinyl acetate with the crotonic acid ammonium salt.

A method is proposed for producing copolymers by heating a solution of copolymer of vinyl acetate and an ammonium salt of crotonic acid in an ammonia current while distilling off the reaction water with solvent vapors. The process is carried out in the absence of a catalyst. It is also proposed to convert copolymers of vinyl acetate with crotonamide into copolymers of vinyl alcohol with crotonamide by treatment with absolute alcohols in the presence of acidic (perchloric acid) or alkali (potassium hydroxide, sodium methoxide) catalysts.

The proposed method for producing copolymers provides copolymers with high heat resistance. For the reaction, copolymers of vinyl acetate (as well as vinyl formate, vinyl propionate, vinyl butyrate) and crotonic acid, containing various amounts of the latter (up to

50 mol. %) and various molecular weights (viscosity). The properties of the products obtained change regularly depending on the content of crotonamide in the copolymer.

Example 1. In a three-necked flask connected to a Dean and Stark trap equipped with a reflux condenser and an ammonia outlet, 16.25 g of a copolymer of vinyl acetate with crotonic acid ammonium salt (containing 27.87 mole% crotonic acid ammonium salt) were added and poured 88 hours of benzene. Ammonia is passed through the reaction mixture and heat is turned on. In 5-10 minutes After the benzene starts to boil in the trap, the first drop of water appears, after which the reaction is completed within 1 hour and 30 minutes. The resulting vinyl acetate / crotonamide copolymer is filtered, washed with benzene and dried in a vacuum dryer at 30 °. The yield of the dry copolymer is 15.2 g (93.6% of the reaction of the copolymer of vinyl acetate with the ammonium salt of crotonic acid). When the reaction

0.95 ml of water was divided (the theoretical amount was 0.96 liters). The copolymer contains 4.02% nitrogen (theoretical-. The content is 4.59%).

Example 2. 20 g of a vinyl propionate copolymer d The crotonic acid ammonium salt (containing 6.4 mol% crotonic acid ammonium salt) is treated with 100 g of benzene, in accordance with Example 1. The dehydration reaction ends after 1 hour and 20 minutes. The resulting vinylpropionate-crotonamide copolymer is filtered, washed with benzene and dried at 30 °. The yield of the dry copolymer is 18.8 g (94% of the reaction between the vinyl propionate copolymer and the crotonic acid ammonium salt). The copolymer contains 0.75% nitrogen (theoretical content 0.90%).

Example 3. 11 g of a copolymer of vinyl acetate with crotonic acid amide (containing; its 10.07 mol% crotonamide) are placed in a three-necked flask equipped with a stirrer, reflux condenser, and a dropping funnel. 51.5 g of absolute methyl alcohol and 0.43 g of potassium hydroxide are added to the flask and

the reaction mixture is heated by placing at 35 °. After 2 hours, the reaction is complete. The precipitated copolymer of vinyl alcohol and crotonamide is filtered off, washed with methanol, dried in a vacuum cleaner at room temperature. The copolymer contains 1.45% nitrogen and 3.69% residual acetate groups. It is soluble in water.

Subject invention

Claims (2)

1. A method of obtaining copolymers based on reaction products of vinyl acetate with crotonic acid ammonium salt, characterized in that, in order to increase the heat resistance of the copolymers, solutions of the products of interaction of vinyl acetate with crotonic ammonium salt are heated in a stream of ammonia while simultaneously removing water from the reaction mixture with solvent solvents . 2. A variation of the method according to claim 1, characterized in that the copolymers obtained are subjected to hydrolysis with absolute alcohols in the presence of acidic or heavy metal catalysts.