Styrene-butadiene based redispersible polymer powders with improved stability in cement applications

摘要

A water redispersible polymer powder is produced by drying an aqueous mixture of a carboxylated styrene butadiene polymer and a colloidal stabilizer which includes a polyvinyl alcohol modified with an alkyl end chain. The alkyl modified polyvinyl alcohol provides excellent redispersibility of the redispersible polymer powder without adversely affecting spray drying. Cement compositions such as mortars, which contain the redispersible polymer powder with the alkyl modified polyvinyl alcohol exhibit unexpectedly superior stability and an unexpectedly lower rate of mortar viscosity buildup which is advantageous for workability or troweling.

主权项

1. A water redispersible polymer powder (RDP) composition comprising an admixture of a water insoluble film-forming polymer which is carboxylated and from 2% by weight to 20% by weight, based upon the weight of the water insoluble film-forming polymer of a colloidal stabilizer, said film forming polymer comprising a carboxylated styrene-butadiene copolymer, and said colloidal stabilizer comprising a combination of a polyvinyl alcohol having an alkyl end chain of from 6 carbon atoms to 20 carbon atoms (alkyl modified polyvinyl alcohol) and an unmodified polyvinyl alcohol wherein the amount of the alkyl modified polyvinyl alcohol is from 5% by weight to 70% by weight based on the weight of the colloidal stabilizer,
optionally, the water redispersible polymer powder composition further comprising cement ingredients in a dry mix formulation of the water redispersible polymer powder in an amount of at least 0.1% by weight, based upon the weight of the dry mix formulation.