FIELD: chemistry of polymers. SUBSTANCE: described is method of preparing water-soluble varnish binders after at least partial neutralization of carboxy groups of varnish binders based on oligourethane and acrylate copolymers, by copolymerization of mixture of acrylic monomers in the presence of oligourethane. Mixture of acrylic monomers includes mixture (A): (Aa) from 40 to 70 wt % of alkylmethacrylates alkyl residues of which have from 2 to 4 carbon atoms (Ab) from 5 to 20 wt % of hydroxyalkyl (meth)acrylates alkyl residues of which have from 2 to 5 carbon atoms, (Ab) from 3 to 15 wt % of methacrylic acid with addition of (Ar) from 10 to 35 wt % of aromatic vinyl compounds, total percentage for components A-(Ar) should constitute 100%, and components (Aa)-(Ar) are selected so that theoretically corresponding acrylate copolymer may have acid number from 30 to 90 mg KOH/g, hydroxyl number from 30 to 50 mg/KOH/g and temperature of transition into vitreous state from -5 go +25 C, and process is carried out in water-diluted organic solvent in the presence of radical polymerization initiator and (B) water-insoluble oligourethane prepared by reacting dihydric alcohol aliphatic ether or mixture of such dihydric alcohol with diisocyanates which does not contain free isocyanate groups and has hydroxyl number from 110 to 150 mg KOH/g, nitrogen content from 2.8 to 3.7 wt % and molecular weight from 750 to 1000, and said oligourethane being subjected to copolymerization provided that amount (B) in final product (AB) varies from 35 to 60 wt % and final product has acid number from 15 to 45 mg KOH/g, hydroxyl number from 75 to 110 mg KOH/g and ultimate viscosity number (1.5 % in chloroform (20 C) from 13.5 to 16.5 ml/g. EFFECT: compositions for use for high-quality water-soluble exterior varnishes of hot drying. 7 cl, 5 ex, 2 tbl
