ALKALI-SOLUBLE RESIN (ASR) SHELL EPOXY RDP EXHIBITING IMPROVED SHELF STABILITY

摘要

The present invention provides shelf stable redispersible multilayer polymer particles (RDPs) comprising a major proportion of epoxy resins, a methacrylic acid or anhydride containing alkali soluble polymer outer layer and a hydrophobic chain transfer agent or a high glass transition temperature colloidal stabilizer, such as poly(vinyl pyrrolidinone) or its copolymer, as well as to methods of making the same.

主权项

1. A redispersible polymer powder composition comprising as powder or an aqueous dispersion multilayer polymer particles of from 50 to 90 wt. % of epoxy resin compositions having a calculated glass transition temperature (Tg) of from 0 to 40° C., and from 10 to 50 wt. %, of an alkali soluble polymer shell around the epoxy resin, which polymer shell is the copolymerized product of from 10 to 50 wt. % of methacrylic acid or its anhydride, based on total weight of monomers copolymerized to form the alkali soluble polymer shell, and the remainder of one or more ethylenically unsaturated comonomer and one or more chain transfer agent,
wherein in the redispersible polymer powder, (i) the alkali soluble polymer comprises in copolymerized form from 0.1 to 10 wt. %, based on total weight of monomers copolymerized to form the alkali soluble polymer shell plus chain transfer agents, of one or more hydrophobic chain transfer agent, (ii) the redispersible polymer powder comprises from 3 to 25 wt. % based on the total weight of epoxy resin, alkali soluble polymer and colloidal stabilizer solids, of one or of a mixture of colloidal stabilizers having a Tg of 90° C. or more, or (iii) both (i) and (ii).