METHOD FOR PREPARING PHENOL-RESORCINOL-FORMALDEHYDE RESIN Russian patent published in 2006 - IPC C08G8/24 

FIELD: chemical industry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of synthetic resins. Invention describes a method for synthesis of phenol-resorcinol-formaldehyde resin. Method involves condensation of phenol with formaldehyde in an aqueous medium in the presence of alkaline metal sulfite at heating and the following condensation of synthesized intermediate compound with resorcinol. Method involves dissolving alkaline metal sulfite in the first part of formaldehyde aqueous solution followed by addition diphenylolpropane as a phenol source up to the mole ratio diphenylolpropane : formaldehyde = 1:1, heating the reaction mixture to the boiling point and its keeping for 15-45 min and cooling to temperature 50-70°C. At the second step the second part of formaldehyde solution is added up to the mole ratio diphenylolpropane : formaldehyde = 1:(2.5-3.5) and the reaction mixture is kept at temperature 60-75°C for 1.5-2.5 h. At the third step co-condensation of synthesized intermediate compound with resorcinol is carried out up to achievement of required solubility in technical water in the volume ratio above 1:20 and prepared resin is dissolved in polar solvent and cooled. Invention provides a method for preparing phenol-resorcinol-formaldehyde resin showing low toxicity, high water-solubility, stability in storing and useful for practical using in different fields of industry.

EFFECT: improved preparing method of resin.

2 tbl, 4 ex