| 摘要 |
Sealing materials (I) are based on aq. acrylate-(copolymer) dispersions (II), and contain 0.1-6 wt.% partly hydrolysed polyvinyl alcohol (III). Prodn. of (I) from (II) comprises opt. adjusting to pH 8, adding the liq. organic components followed by pigments and fillers, and then adding (III) as a conc. aq. soln. Pref. (III) is added as a 30-40 wt.% aq. soln., pref. contg. foam suppressants and/or biocidal agents. Pref. (III) has deg. of hydrolysis (DH) of 42-97 (pref. 79-92)% and viscosity (4% aq. soln.) of 2-60 (pref. 15-30) mPa.s. (II) is an aq. dispersion of poly(meth)acrylate of (meth)acrylate copolymer, pref. obtd. by polymerisation of alkyl (meth)acrylates (IV) and/or copolymerisation of (IV) with (meth)acrylic acid, (meth)acrylamide, styrene, itaconic acid, acrylonitrile and/or citraconic acid etc., esp. a dispersion of poly0butyl or poly-ethylhexyl acrylate or alkyl (meth)acrylate/styrene copolymer. (II) has solids content 40-70 (pref. 45-65) wt.% and pH 7-9, pref. 8. (I) also contains plasticisers, fillers, pigments, rheology modifiers, dispersants, biocides, preservatives, anti-ageing additives, wetting agents, foam suppressants and/or skinning retarders. USE/ADVANTAGE - Incorporation of (III) gives sealants (I) (e.g. for building applications) with improved resistance to rain directly after application |
