| 摘要 |
1,235,752. Vinyl aromatic/maleic anhydride copolymers. DOW CHEMICAL CO. 3 July, 1968, No. 31790/68. Heading C3P. A process for batch polymerization of vinyl aromatic and maleic monomers, viz. maleic anhydride or C 1 -C 4 alkyl acid maleates, the resultant copolymer having a mole ratio of greater than 4 parts vinyl aromatic to one part maleic monomer, a viscosity of less than 0À9 cps. when measured in a 10% by weight solution in methylethylketone at 25‹ C. and having greater than 95 weight per cent of the copolymer within a range of 5 weight per cent maleic monomer content by fractionation analysis, which process comprises heating a polymerization solvent having a boiling point between 140-250‹ C. to reflux in an inert atmosphere and initially charging to the solvent 5 to 15 weight per cent of the total monomeric feed of vinyl and maleic monomers, the composition of the charge being calculated from the equation r 1 x = n - 1, wherein r 1 is the reactivity ratio for the reaction temperature and maleic monomer, x: 1 is the mole ratio of vinyl monomer to maleic monomer in the charge and A :1 is the mole ratio of vinyl to maleic monomer combined in the desired polymer, within 5 minutes feeding to the solvent a second charge of the vinyl and maleic monomer in a mole ratio of vinyl to maleic monomer of n: 1 together with a polymerization catalyst at a constant rate so as to maintain a constant-amount of vinyl monomer in the reactor, and thereafter carrying out the last 5 to 15 weight per cent polymerization by feeding to the solvent the remaining maleic monomer at rate equal to the rate of copolymerization of the vinyl monomer and terminating the reaction at greater than 95% by weight conversion. The vinyl aromatic monomer may be styrene, vinyl toluene, t-butyl styrene, vinyl xylene and/or -chlorostyrene or mixtures thereof with α-methyl styrene. When acid maleates are used, the polymer is de-esterified during and after polymerization by the distillation of. the alcohol component to produce the anhydride polymer. |
