SYNTHETIC RESIN AND THE METHOD OF ITS PRODUCTION Russian patent published in 2007 - IPC C08G12/40 

FIELD: chemical industry; building materials industry; methods of production of the synthetic resin.

SUBSTANCE: the invention is pertaining to the synthetic resin and the method of its production. The synthetic resin is used predominantly in production of the wood chipboards, plywood and the glued joints of wood. The resin is produced by interaction of carbamide and formaldehyde at presence of the starch oxidized reactant at the following ratio of the components (in mass %): carbamide - 58.2-68.1; formaldehyde -29.0-37.9; the starch oxidized reactant - the rest up to 100. The produced resin has the molecular mass of no less than 1000. The method of the resin production provides for preparation of the reaction mixture on the basis of carbamide and formaldehyde with рН = 7.0-7.5 at the ratio of carbamide to formaldehyde equal to 1:2 mole. The first stage of the process includes the heating of the mixture to the temperature, which does not exceed the boiling temperature and keeping at this temperature during the time necessary for formation of the hydroxyl hydroxymethyl groups. The second stage includes the condensation at decreasing рН to 4.2-4.5 and keeping the initial temperature during the time necessary for formation of the oligomer with the degree of the polycondensation of 6-10, neutralization of the of a condensation solution to рН = 6.7-7.0. The third stage provides for reduction of the temperature by 20-27°С with the regard to the initial temperature. The fourth stage includes introduction of the additional batch of carbamide, the additional condensation with the subsequent cooling to the room temperature. At that prior to the beginning of the fourth stage the reaction mixture is introduced with the starch oxidized reactant in amount of 1-25 mass shares with respect to the theoretically dry substance per 100 mass shares of the theoretically dry formaldehyde. At that the molar ratio of the carbamide to the formaldehyde after the fourth stage makes 1 : (0.85-1.30). The technical result of the invention is reduction of the free formaldehyde contents at the simultaneous increase of the index of miscibility of the resin with the water.

EFFECT: the invention ensures reduction of the free formaldehyde contents at the simultaneous increase of the index of miscibility of the resin with the water.

8 cl, 5 ex, 1 tbl