Self-coalescing latex

摘要

The present invention relates to self-coalescing latexes that incorporate film fat ing polymers that are low molecular weight polymers that are compatible with the latex and act as thin plasticizers penetrating through the remainder of the latex particle and aiding in the coalescence of the remaining polymers. In a preferred embodiment, the self-coalescing latex is a sequentially polymerized polymer having at least a core, a shell and a skin. The film forming polymers are formed of monomers substantially the same as the monomers of the shell but having average weighted molecular weights substantially less than the polymers of the shell. The present invention also relates to the method of polymerizing the self-coalescing latex of the current invention, which largely results from the addition of a substantial amount of chain transfer agent to a remaining portion, about 15% or less, of the monomer pre-emulsion prior to polymerization. Lastly, the invention relates to paint compositions incorporating the self-coalescing latexes that are substantially free of coalescing agents or aids.

主权项

1. A self-coalescing latex comprising a sequentially designed polymer comprised of at least
from about 10 to about 50% by weight of hard monomers forming a first stage of the latex having a glass transition temperature from about 50° C. to about 130° C., from about 10 to about 60% by weight of soft monomers forming a second stage of the latex having a glass transition temperature from about −10° C. to about 50° C., and from about 0 to about 10% by weight of hydrophilic, hydrophobic or functional monomers wherein the polymer further comprises a film forming polymer having a weighted average molecular weight of less than about 40,000 Daltons and is present in about 0.5% by weight to less than about 10% by weight of the polymer.