Process for the production of emulsifier-free, self-crosslinkable rubber latices

Claim 1

A process for the production of an emulsifier-free self-crosslinkable rubber latex from 1 to 6 parts by weight of (meth)acrylic acid, 0.5 to 6 parts by weight of N-alkoxymethyl (meth)acrylamide and 88 to 98.5 parts by weight of a mixture of 10 to 90 parts by weight of one or more acyclic conjugated dienes containing from 4 to 9 carbon atoms and 10 to 90 parts by weight of one or more arylvinyl monomers containing from 8 to 12 carbon atoms and/or (meth)acrylonitrile, the quantity of (meth)acrylonitrile amounting to at most 50 parts by weight, characterised in that (a) an aqueous emulsion is prepared by adding at least part of the (meth)acrylic acid, part of the diene and further monomers to water, (b) the polymerisation reaction is initiated by the addition of an aqueous solution of a peroxodisulphate, (c) polymerisation is carried out in a first stage at a pH-value of from 3.5 to 7 and at a temperature above 70° C. until at least 50% of the monomers have been polymerised, (d) the rest of the monomers and more aqueous peroxodisulphate solution are added in one or more further stages, (e) the polymerisation reaction is continued at a pH-value of from 3.5 to 7 and at a temperature above 70° C. until at least 50% of the monomers have been polymerised and, in the last stage, until from 85 to 100% of the monomers have been polymerised.