PROCESS FOR THE PRODUCTION OF HIGH SOLIDS LATEX

摘要

By utilizing the process of this invention latices having solids contents of greater than 40 percent can be prepared with minimal microcoagulum formation. These latices can be used in making paint formulations which have improved storage stability. This invention more specifically discloses a process for preparing a latex having a high solids content which comprises the steps of (1) terpolymerizing a vinyl aromatic monomer, an alkyl propenoic acid ester, and an alkyl propenoic acid monomer in an aqueous polymerization medium by free radical polymerization in a first polymerization step to produce a seed polymer latex; (2) neutralizing the seed polymer latex to a pH of about 7 to about 10 by the addition of an alkali to produce a neutralized seed polymer latex; (3) adding additional vinyl aromatic monomer and alkyl propenoic acid ester to the neutralized seed polymer latex and allowing the additional vinyl aromatic monomer and the additional alkyl propenoic acid ester to polymerize in a second polymerization step to a solids content of at least about 40% to produce the latex having the high solids content; wherein about 20 percent to about 40 percent of the total amount of monomers polymerized in the first polymerization step and the second polymerization step are polymerized in the first polymerization step; and wherein the additional vinyl aromatic monomer and the additional alkyl propenoic acid ester are added in the second polymerization step at rate whereby a monomer conversion of at least 85 percent is maintained at all times.