| 摘要 |
<p>An aq. latex which forms contactable layers after drying contains (A) an amorphous copolymer, with modal mol. wt. Mp of 100,000-700,000 and Tg of -50 to below 0 deg.C, contg. vinylidene chloride and an internally plasticising comonomer, and (B) an amorphous copolymer contg. vinylidene chloride and a 1-12C alkyl or alkoxy- (1-12C alkyl) (meth)acrylate, styrene, acrylonitrile, vinyl acetate and/or vinyl ethyl ether, and with Tg 0-80 deg.C. The dry wt. ratio of A:B is 95:5 - 10:90. The ratio A:B is pref. 85:15-15:85. Copolymer A has Tg -40 to -5 deg.C, and contains 10-70 (20-60)% of vinylidene chloride, 30-90 (40-80)% of internal plasticiser (pref. n-butyl or 2-ethylhexyl acrylate), 0-20% vinyl chloride and 0-10 (0.1-8)% of an ethylenically unsatd. acid. The Mp is 100,000-500,000. A is pref. prepd. by monomer flooded copolymerisation. Copolymer B has Tg 2-60 deg.C, and contains 10-70 (35-70)% of vinylidene chloride 2-90 (5-90)% of (meth)acrylates, styrene, acrylonitrile, vinyl acetate or vinyl ethyl ether (esp. methyl methacrylate + n-butyl acrylate), 0-50% of vinyl chloride, 0-10 (0.1-8)% of an ethylenically unsatd. acid, and opt. an internally plasticising monomer. The unsatd. acid in A and B may be an ethylenically unsatd. carboxylic acid or sulphonic acid, pref. an aliphatic, alpha,beta-unsatd. carboxylic acid. Copolymer A and/or B may contain a crosslinking comonomer. The compsn. may contain a tackifying resin.</p> |
