DETAILED DESCRIPTION OF THE INVENTION The rubbery polymers of this invention are synthesized utilizing a free radical emulsion polymerization technique.
These rubbery polymers are comprised of repeat units which are derived from (a) butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40% 2-ethylhexyl acrylate, (b) methyl methacrylate, ethyl methacrylate, methyl acrylate, or ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a half ester maleate soap, and (f) a crosslinking agent.
The crosslinking agent is typically a multi-functional acrylate, a multi-functional methacrylate or divinylbenzene.
Some specific examples of crosslinking agents which can be used include ethylene glycol methacrylate, divinylbenzene, and 1,4-butanediol dimethacrylate.
Technically, the rubbery polymers of this invention contain repeat units (chain linkages) which are derived from (a) butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40% 2-ethylhexyl acrylate, (b) methyl methacrylate, ethyl methacrylate, methyl acrylate, or ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a half ester maleate soap, and (f) a crosslinking agent.
These repeat units differ from the monomers that they were derived from in that they contain one less carbon-carbon double bond than is present in the respective monomer.
In other words, a 10 carbon-to-carbon double bond is consumed during the polymerization of the monomer into a repeat unit in the rubbery polymer.
Thus, in saying that the rubbery polymer contains various monomers in actuality means that it contains repeat units which are derived from those monomers.
The rubbery polymers of this invention will normally contain (a) from about 40 weight percent to about 80 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to 40 weight percent 2-ethylhexyl acrylate, (b) from about 5 weight percent to about 35 weight percent methyl methacrylate, ethyl methacrylate, methyl acrylate, or ethyl acrylate, (c) from about 4 weight percent to about 30 weight percent acrylonitrile, (d) from about 3 weight percent to about 25 weight percent styrene, (e) from about 0
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Nonmetallic Processes 
