| 摘要 |
This invention relates to the synthesis of a latex which can be used in making water reducible coating compositions, such as paints, which contain no or extremely low levels of volatile organic compounds. Coatings which are formulated with the latex of this invention offer an environmental advantage as well as excellent flexibility, excellent ultra-violet light resistance, and good water resistance. This invention more specifically discloses a process for producing a neutralized latex that is useful in the manufacture of water reducible coatings which comprises: (1) free radical aqueous emulsion polymerizing, at a pH of less than about 3.5, a monomer mixture which comprises, based on 100 weight percent monomers: (a) from about 30 to about 70 weight percent vinyl aromatic monomers, (b) from about 25 to about 65 weight percent of 2-ethylhexyl acrylate, (c) from about 1 to about 5 weight percent of acrylic acid, and (d) about 0.4 to about 3 weight percent methacrylic acid to produce a latex; wherein said emulsion polymerization step is conducted in the presence of about 0.5 to about 4 phm at least one phosphate ester surfactant and in the presence of about 0.5 to 4 phm of at least one water insoluble nonionic surface active agent selected from the group consisting of nonionic surfactants having a hydrophile-lipophile balance number of less than about 12, fatty alcohols, and polyols which are copolymers of ethylene oxide and propylene oxide; and (2) neutralizing the latex with ammonia to a pH which is within the range of about 7 to about 10.5 to produce the neutralized latex. |
