| 摘要 |
Heterogeneous, solvent- and plasticizer-free polyvinyl ester dispersions which are stabilized by protective colloids and which have a minimum filming temperature of below 10 DEG C. are disclosed. These dispersions are made of a mixture of (a) a homopolymer or copolymer A having a glass transition temperature of above 20 DEG C., whereby homopolymer or copolymer A includes (i) from 85 to 100% by weight of at least one vinyl ester of carboxylic acids having 1 to 18 carbon atoms; (ii) from 0 to 5% by weight of at least one alpha , beta -unsaturated carboxylic acid; (iii) from 0 to 5% by weight of at least one mono-olefinically unsaturated compound (a3) having at least one amino or amido group, and (iv) from 0 to 5% by weight of at least one polyethylenically unsaturated monomer, and (b) a copolymer B having a glass transition temperature of below 20 DEG C., whereby copolymer B includes (i) from 45 to 98% by weight of at least one vinyl ester of carboxylic acids having 1 to 18 carbon atoms; (ii) from 2 to 50% by weight of at least on alpha -mono-olefin having 1 to 4 carbon atoms and (iii) from 0 to 5% by weight of at least one polyethylenically unsaturated monomer. Also disclosed are powders obtained from these dispersions by spray-drying, and dispersion prepared by redispersing the spray-drying powders. These materials are suitable as adhesives for bonding porous and semiporous substrates.
|
