SU927801A1 - Process for producing copolymers containing acrylamide and acrylonitrile links - Google Patents

Description

The invention relates to high molecular compounds, in particular to the preparation of polymers containing acrylamide and acrylonitrile units, which can be used in the chemical industry and, in particular, in the preparation of synthetic fibers based on polyacrylonitrile.

A method of producing polymers containing acrylamide and acrylonitrile units is known, by copolymerizing acrylonitrile with acrylamide in a 51.5% aqueous solution of sodium rhodanate, for 30-60 minutes 1.

However, the conversion of acrylonitrile reaches .85-90%, and the conversion of acrylamide is complete. Consequently, this process requires the removal of unreacted acrylonitrile and its return to the polymerization stage, which complicates the technological scheme. In addition, acrylamide is a very scarce and expensive monomer.

A known method for producing similar polymers by hydrolysis of polyacrylonitrile in the presence of sulfuric acid. Sulfuric acid hydrolysis of polyacrylonitrile is carried out at

20-25 ° C and a process time of 5 hours, after which the polymer containing acrylamide and acrylonitrile units from the reaction mixture is precipitated with water and then washed with plenty of water to remove sulfuric acid. An attempt to shorten the reaction time due to an increase in temperature does not lead to the desired result, since in this case polymers are obtained that do not contain acrylonitrile units 2.

15 The disadvantages of the method are

large amounts of wastewater, laborious separation of the reaction mixture, disposal of large quantities of dilute sulfuric acid, which

20 is formed in the polymer isolation stage.

The closest to the proposed technical essence is a method for producing copolymers containing acrylamide and acrylonitrile units by hydrolyzing polyacrylonitrile in an aqueous solution of rhodium salts in the presence of an inorganic or organic catalyst.

30 bases 3.

The disadvantage of this method is the need to wash out and / or neutralize the base after reaching the desired degree of hydrolysis, which complicates the technology.

The purpose of the invention is to simplify the technology.

This goal is achieved in that according to the method for producing copolymers containing acrylamide and acrylonitrile units by hydrolyzing polyacrylonitrile in an aqueous solution of rhodium salts, in the presence of a catalyst, manganese dioxide or a catalyst is used as a catalyst. based on activated metallic copper.

In the proposed method, the catalyst is removed from the reaction mass by filtration and can be used many times.

As a result of hydrolysis, polymers are obtained containing 5-50% acrylamide units. At the same time, the reaction time is 30-60 minutes. In the case of using partially hydrated polyacrylonitrile in the production of synthetic fiber, the reaction mass obtained by hydrolysis can be directly used to form the fiber.

Example 1.30G Dewar alloy (50% Cu, 45% A and 5% Zn) is treated with 200 ml of a 25% aqueous solution of caustic soda at 20–25 ° C for 15 h. The precipitate is filtered and shed with water until neutral and the resulting skeletal copper catalyst used in the hydrolysis of polyacrylonitrile.

In a glass vial, 2 g of a skeletal copper catalyst and 0.3 g of polyacrylonitrile (intrinsic viscosity 3.9 dl / g) dissolved in 15 ml of a 52% aqueous solution of rhodanite cache and stirred for 30 minutes at 80 s. From the reaction mixture, the polymer is precipitated with water, then washed with water until a negative reaction, potassium rhodium, and after drying, analyzed by IR spectroscopy, and the content of nitrogen in it is determined by which the composition of the copolymer is judged. 0.32 g of polymer was isolated, which contains 5% acrylamide units and 95% acrylonitrile units. Inherent viscosity 4.0 dl / g.

The results of examples 2-4, carried out according to the method of example 1, are presented in table. one.

Table 1

Example 5. 2 g of manganese dioxide and 10 ml of a 8.2% solution of polyacrylonitrile 45 (intrinsic viscosity 4.0 dp / g) in a 52% aqueous solution of rhodium sodium are placed in a vial. The ampoule is kept at 80 ° C for 1 h, after which the viscous reaction mass is diluted with 10 ml of water;

4.0 8.2

th solution of rhodium sodium. The catalyst is filtered off and the polymer is precipitated with water. In the polymer obtained (0.35 g), 32% acrylamide units and bv% acrylonitrile units were found. The results of experiments 6-9 are given in table. 2

table 2

36

.thirty

41 40 52

100

Claims (3)

30 60 60 100 100 Example 10. 20 g of the catalyst СНМ-1 (55% CuOf 26% ZnO; 10% residual moisture) are placed in a heated tube and for 15 hours a mixture of nitrogen and hydrogen (20 o6) is blown through the catalyst bed. %) at a rate of 50 ml / min. Under these conditions, with only copper oxide, while the other oxides that make up the catalyst do not undergo changes, 3 g of the reduced catalyst and are placed in a glass ampoule. 0.4 g of polyacrylonitrile dissolved in 15 ml of a 52% solution of the genus potassium gum and kept under stirring for 1 hour at lOOc. Next, the reaction mass is treated as in Example 1. 0.45 g of a polymer containing 35% acrylamide and 65% acrylonitrile was isolated. Thus, the use of the invention makes it possible to simplify the technology of producing copolymers containing acrylamide and acrylonitrile units, with the possibility of multiple uses of used catalysts. The method of obtaining copolymers containing acrylamide and acrylonitrile units by hydrolysis of polyacrylonitrile in an aqueous solution of rhodium salts in the presence of a catalyst, characterized in that, in order to simplify the technology, manganese dioxide or an catalyst based on activated metallic copper is used as a catalyst. Sources of information taken into account in the examination 1.Vurd. other. Investigation of the conditions for the preparation of acrylonitrile copolymer with acrylamide and the properties of fibers based on it. - Journal of Applied Chemistry. № 1, t. 49, 1976, from 2685-2688. 2. Zilberman B.N. other. The conversion of polyacrylonitrile and copolymers of acrylonitrile with isobutylene in the presence of sulfuric acid. - High molecular weight compounds. №7, t. A15, 1973, p. 1648-1653. 3. For Germany FRG 2552614, cl. C 08 F 8/12, 1978 (prototype).