the polymerization it is preferred to add from about 6 parts by weight to about 22 parts by weight of parts by weight to 1 part by weight of the crosslinking agent it is typically more preferred for from about 10 parts by weight to about 17 parts by weight of styrene from about 4 parts by weight to about 8 parts by weight of acrylonitrile and from about 0 1 parts by weight to about 0 5 parts by weight of the crosslinking agent to be added to the seed polymer latex to initiate the second phase of the polymerization a wide variety of crosslinking agents can be utilized in carrying out the polymerizations of this invention some representative examples of crosslinking agents that can be utilized include difunctional acrylates difunctional methacrylates trifunctional acrylates trifunctional methacrylates and divinylbenzene a crosslinking agent that has proven to be particularly useful is 1 4 butanediol dimethacrylate the half ester maleate soap that can be utilized in the polymerization is prepared by reacting maleic anhydride with a fatty alcohol containing from about 10 to about 24 carbon atoms it is typically preferred to utilize a fatty alcohol which contains from about 12 to about 16 carbon atoms one mole of the maleic anhydride is reacted with one mole of the fatty alcohol in producing the half ester maleate soap this reaction is typically conducted at a temperature which is within the range of about 50 u00b0 c to about 80 u00b0 c and can be depicted as follows str2 sodium hydroxide or potassium hydroxide is then typically added to make the half ester maleate soap.