METHOD FOR PRODUCTION OF ETHYLENE-VINYL ACETATE COPOLYMERS Russian patent published in 2000 - IPC

FIELD: polymer production. SUBSTANCE: ethylene-vinyl acetate copolymers are prepared in high-pressure radical copolymerization carried out in single- or multizone tubular reactor provided with reaction mixture cooling system in each reactor zone. Unreacted reaction mixture, containing ethylene, vinyl acetate, and copolymers, is separated in high- and low-pressure recycle system, and high- and low-pressure recycle mixtures are added to stream containing initial ethylene. Process is distinguished by that additional vinyl acetate is fed into each reaction zone at points corresponding halve reaction mixture conversion attained in given zone. Amount of additional vinyl acetate (G_rm, kg/h) is estimated from formula: G_va = K*G_rm*C*q/2, where G_va is amount of reaction mixture fed into reaction zone, kg/h; C content of vinyl acetate in mixture, wt %; q conversion of reaction mixture in given zone, wt %; and K is constant equal to (0.90-1.33)*10^-4. EFFECT: improved working characteristics of copolymer due to its homogeneity. 2 dwg, 1 tbl, 11 ex