METHOD OF PREPARING BUTADIENE-NITRILE RUBBERS Russian patent published in 2001 - IPC

FIELD: manufacture of industrial rubber products. SUBSTANCE: described is method for preparing butadiene-nitrile rubbers by aqueous emulsion copolymerization of butadiene and acrylic acid nitrile in the presence of emulsifier, e.g. soap of tall oil fraction, initiator, molecular weight regulator by feeding acrylic acid nitrile: 66-80 wt % at the beginning of process and 10-17 wt %, 25-30 and 40-50 wt %, during conversions of monomers. Process is carried out at emulsifier content of 2.5-2.7 wt % and 5-25 wt % of first portion of acrylic acid nitrile as 2-7 % aqueous solution are premixed with aqueous phase at said acrylic acid nitrile solution to aqueous phase ratio of 1:2-10 by volume, respectively, and 73-95 wt % of first portion is added in the form of acrylic acid nitrile. Method makes it possible to increase stability of latex, reduce content of emulsifier and reduce content of impurity of emulsifier in the resulting rubber product and also improve physico-mechanical and frost resistance characteristics of rubbers. EFFECT: more efficient preparation method. 5 ex, 2 tbl