Abstract: The invention relates to a process and an apparatus for producing a profiled sheet, in which the sheet is provided with a corrugation which runs obliquely with respect to the edges of the sheet and has a substantially constant angle of inclination. At least one edge region of the sheet is deformed by means of a ram-like deformation tool (6) which is alternately brought into contact with the edge region and removed from the edge region.

Abstract: Polymer microparticles having a three-dimensional network structure and an average particle size of 0.01 to 1 micron are obtained by emulsion polymerization of ethylenically unsaturated monomeric composition containing (a) at least one polyfunctional monomer having a plurality of polymerizable sites, or (b) a combination of two ethylenically unsaturated monomers each bearing mutually reactive functional groups in an aqueous medium in the presence of a compound or resin having a betaine group. The betqine compound or resin is incorporated into the polymer microparticles by physically adhering or covalently binding thereto to enhance the dispensing stability of the microparticles over a wide range of pH.