USE OF STYRENE-MALEIC ANHYDRIDE COPOLYMERS (SMA RESINS) IN EMULSION COPOLYMERIZATION

The composition and quantity of styrene-maleic anhydride (SMA) copolym er resins were varied in emulsion copolymerizations of methyl methacry late and n-butyl acrylate conducted by both batch and semicontinuous p rocesses. The resulting particle sizes and levels of coagulum were mea sured to determine the optimum conditions for incorporation of the SMA resins into the resulting latexes. A semicontinuous process, in which no buffer was included and the SMA was added in a second stage comono mer emulsion, was found to produce coagulum-free latexes. These recipe s, however, relied on nucleation of the polymer particles by conventio nal surfactants [nonyl phenol poly(ethylene) oxide and its correspondi ng sulfate salt] with a first-stage addition of a monomer emulsion pre pared with these surfactants. SMA1000, having a 1/1 ratio of styrene t o maleic anhydride in its copolymer, was determined to be the preferre d resin las opposed to SMA2000 and SMA3000, having SMA ratios of 2/1 a nd 3/1, respectively) because it interacted the least with conventiona l surfactants, which allowed its ready incorporation into coagulum-fre e recipes. (C) 1998 John Wiley & Sons, Inc.