METHOD FOR PREPARING ACRYLIC ACID Russian patent published in 2005 - IPC

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing synthetic high-molecular compounds, in particular, polyacrylic acid. Invention proposes a method for preparing polyacrylic acid by radical polymerization of monomer dissolved in a solvent in the present of an initiating agent. Isolation of polyacrylic acid is carried out by four-steps distillation off of a solvent under vacuum wherein at the first step distillation off is carried out under the residual pressure 110-550 mm of mercury column, intensive stirring and temperature 85-104°C; at the second step distillation off is carried out under the residual pressure 20-100 mm of mercury column and temperature 60-85°C; at the third step - under the residual pressure 10-20 mm of mercury column, at slow stirring and temperature 55-60°C; at the fourth step - under the residual pressure 3-10 mm of mercury column, at minimal rate of a mixer and at temperature 50-55°C. The polymerization process of acrylic acid is carried out at temperature 102-104°C for 60-70 min since the induction moment period termination after addition of the preliminary prepared polymerization mixture containing acrylic acid and an initiating agent dissolved in a solvent to a solvent heated to 94-95°C. The proposed method shows simplicity and economy and doesn't require the complex equipment. The prepared anhydrous polyacrylic acid powder is used in medicine, in particular, for making the cement filling composition used in therapeutic stomatology. Invention provides the development of a method for preparing high pure, finely dispersed, powder-like and easily dosing anhydrous polyacrylic acid.

EFFECT: improved preparing method.

3 cl, 1 ex