JPS6261048B

1. A process for the production of 30 to 45% by weight aqueous acrylonitrile copolymer dispersions having an average particle diameter of =< 90 nm, as determined by the light scattering method, and a residual monomer content of acrylonitrile of =< 500 ppm by the emulsion polymerisation of from 5 to 50 parts by weight of acrylonitrile and from 50 to 95 parts by weight of at least one other vinyl monomer - the sum of the parts by weight is 100 - at temperatures of from 40 to 80 degrees C in the presence of at least one water-soluble radical former or redox system and in the presence of at least one anionic emulsifier and, optionally, the usual auxiliaries, up to a substantially complete conversion of the monomers, characterised in that at least one anionic emulsifier of the formula (I) : see diagramm : EP0005221,P6,F2 in which R**1 represents a saturated or straight-chain alkyl radical containing from 5 to 12 carbon atoms, n = 0 or 1, and m = 2 to 12, and Me represents an alkali metal or ammonium, is used in a total quantity of from 1 to 4 parts by weight - based on 100 parts by weight of monomer from 60 to 95% by weight of the quantity of emulsifier and from 4 to 20% by weight of the total quantity of monomers being initially introduced in most of the water, polymerisation being initiated with an aqueous solution of the radical former or the redox system, and from 5 to 40% by weight of the quantity of emulsifier in the rest of the water and the balance of the monomers subsequently being added.