| 摘要 |
Copolymers (I) for use as thixotropic thickening agents for aq. coating systems contain repeat units derived from ethyl acrylate (EA), methacrylic acid (MAA), and a water-soluble crosslinking monomer (I) selected from alkylene bisacrylamides and ethylene glycol dimethacrylate; in wt. % ratio 25-55:45-75:0.05-0.75 (most pref. 35-45:55-65:0.1-0.3). Brookfield RVT viscosity (50 rpm; no.3 spindle) of a 2 wt. % aq. soln. at pH7-8 is 50-2000 (pref. 700-1000) mPa. s. Also claimed are aq. coating compsns. (II) comprising (a) a water-reducible resin; (b) (I); (c) pigment; (d) plasticiser; and (e) water. The resin contains repeat units from (i) styrene, alpha-methy-lstyrene and vinyl toluene; (ii) 3-5C alkyl acrylate(s); and (c) carboxylic monomer(s) from (meth)acrylic, fumaric, itaconic and maleic acids and maleic anhydride; in wt. % ratio (i):(ii):(iii) 50-90:10-40:1-10.
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