Abstract: Producing spherical polymers having a weight-averaged average particle diameter of 1 to 50 &mgr;m using a seed/feed process comprising the following steps: a) suspension of a monodisperse spherical seed in an aqueous phase, b) addition of at least one monomer and an initiator, c) polymerization of the monomer, of which there is at least one, wherein the seed consists of a polymer having a comb structure, gives rise to products having a particularly narrow grain size distribution.

Abstract: The present invention relates to a process for the preparation of microencapsulated polymers having a high surface smoothness, a soluble fraction of less than 6%, and a swelling index of between 1.3 and 9 by polymerizing a microencapsulated monomer mixture suspended in an aqueous phase containing at least one hydroxyaromatic compound as polymerization inhibitor, wherein the microencapsulated monomer mixture contains (a) 34 to 99.7% by weight of a monomer having one polymerizable C═C double bond, (b) 0.1 to 15% by weight of a crosslinking agent having at least 2 polymerizable C═C double bonds, (c) 0.2 to 1.0% by weight of at least one aliphatic peroxyester as polymerization initiator, and (d) 0 to 50% by weight of additives, the percentages being based on the sum of the components (a) to (c).

Abstract: This invention relates to spherical methyl methacrylate copolymers with an average particle size of 6 to 50 .mu.m and a narrow particle size distribution, and to a method of producing them. The invention further relates to the use of these spherical copolymers for the production of 3-D models by laser sintering.