| 摘要 |
0.05-3 % by weight of a mixture of the following components which is free from mineral oxides, such as SiO2 or Al2O3, are used as defoamer (defoaming agent, foam breaker, foam suppressant) in aqueous dispersions and solutions of synthetic resins: A) 1-20 % by weight of a polydimethylsiloxane-polyoxyalkylene block polymer built up from 10-60 % by weight of methylsiloxane units and 90-40 % by weight of oxyalkylene units, in particular 75-10 % by weight of oxypropylene units and 0-25 % of oxyethylene units, and B) 99-80 % by weight of at least one neutral [lacuna] built up from mono- or dicarboxylic acids containing 4-12 carbon atoms and monoalcohols containing 4-12 carbon atoms, and preferably containing branched radicals. Component A) conforms to the formula (I) or (II) <IMAGE> Me = methyl, A = CH2CH2CH2O-(C3H6O)m-(C2H4O)n- or -O-(C3H6O)m-(C2H4O)n, X = A or a single bond, R = H or C1-4-alkyl or C2-12-acyl, a = 1-100, b = 0-50, c = a or 0, d = 0 or a, e = 0-2, m = 1-100, n = 0-20, with the proviso that, if X = a single bond, m is greater than n. An increase in the foam inhibition is possible by adding polysiloxanes of the formula (III), where the A):(III) mixing ratio is from 5:1 to 50:1. HO-SiMe2-(O-SiMe2)x-OSiMe2-OH (III> where x = 10-50 and Me = methyl.
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