METHOD FOR OBTAINING 40% AQUEOUS SOLUTION OF POLYACRYLIC ACID FOR DENTISTRY Russian patent published in 2021 - IPC C08F120/06 C08F220/06 C08F2/10 A61K6/00 

FIELD: dentistry.

SUBSTANCE: present invention relates to a method for producing a 40% aqueous solution of polyacrylic acid (hereinafter – PAA) for dentistry. This method involves the polymerization of acrylic acid in an aqueous medium in the presence of the initiator alpha, alpha’-azoisobutyronitrile. In the homogenizer, a polymerization mixture is prepared by mixing acrylic acid for 15-20 minutes with the addition of an initiator taken in an amount of 1.8-2.1 wt.% relatively to acrylic acid. Water is added to the finished polymerization mixture and the mixture is fed from the homogenizer to the reactor with water preheated to 94±1°C at a speed of 126 cm³/min. The polymerization process is carried out at a temperature of 94±2°C and constant mixing at a speed of 200 rpm. After the end of the feeding of the monomer mixture, the mixture is kept in the reactor, while mixing for 25-35 minutes at a temperature of 97±1°C. The 19-21% aqueous solution of PAA obtained at the end of the polymerization process is concentrated by vacuum distillation of water. In the reactor, the number of mixer rotations is increased from 200 rpm to 400 rpm, while gradually reducing the residual pressure from 0.6 atm to 0.15 atm, and also gradually reducing the temperature to 60°C. The resulting product is highly pure, free of foreign impurities and unpleasant smells that are unacceptable for the oral cavity of patients.

EFFECT: technical result is the development of a method for producing a 40% aqueous solution of polyacrylic acid without the use of a molecular weight regulator, which has a compressive strength of -70 MPa and a solidification time of 6-7 minutes.

1 cl, 2 ex