| 摘要 |
<p>An emulsion polymerisation process for making a low mol.wt., alkali-soluble copolymer of a water-insol. monoethylenically unsatd. aromatic monomer and methacrylic acid, comprises (1) heating to 75 deg.C or above, an aq. reaction mixt. having a pH of 4.5 or less, comprising (a) 25-75 pts.wt. water-insol. monoethylenically unsatd. aromatic monomer, (b) 25-75 pts.wt. methacrylic acid, (c) a polymerisation initiator; (d) a reducing agent, (e) a catalyst effective for promoting decompsn. of (c) in the presence of (d), and (f) sufficient chain transfer agent to limit the copolymer Mw to 2000-40000; and (2) maintaining the reaction mixt. at 75 deg.C or above for sufficient time to allow formation of the copolymer. (a) Pref. comprises styrene, alphamethyl styrene, vinyl toluene, vinyl xylene, ethyl vinyl benzene, vinyl benzyl chloride and/or vinyl naphthalene. Prefd. is styrene. (c) pref. comprises ammonium persulphate, Na persulphate and/or K persulphate. Prefd. is ammonium persulphate. (d) pref. comprises Na bisulphate, ascorbic acid, isoascorbic acid, Na formaldehyde sulphoxylate and/or Na hydrosulphite. Prefd. is Na bisulphite. (e) is pref. a transition metal cpd. comprising FeSO4.7H2O, FeCl2, CuSO4, CuCl2, Co(III) acetate and/or Co(II) sulphate. Prefd. is FeSO4.7H2O. (f) is pref. selected from alkyl mercaptans, esters of mercapto acetic acid and/or esters of mercapto propionic acid. Prefd. (f) comprises methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, the ethyl ester or 2-ethylhexyl ester of mercapto acetic acid and/or the isooctyl ester of mercaptopropionic acid.</p> |
