Abstract: A process for the preparation of a prepolymer amide, by hydrolytically polymerizing a lactam/water mixture of a C.sub.12 -aminocarboxylic acid lactam at a temperature in the range from 240-360.degree. C. and a steam pressure in the range of 30-180 bar, and wherein the water content of the lactam/water mixture is in the range of 7.5-30% by weight.

Abstract: A process produces a free flowing, silicic-acid-filled, powdered elastomer wherein the silicic acid employed has the properties set out below:(a) SiO.sub.2 content: about 82-91.5% by weight;(b) metallic oxides: about 0.5-3% by weight;(c) loss on ignition (DIN 55 921/2--measured at 100.degree. C.): about 8-15% by weight;(d) moisture (DIN 53 198--measured at 105.degree. C.): about 2-10% by weight;(e) surface area of the primary particles according to BET: about 40-250 m.sup.2 /g;(f) dibutyl phthalate absorption (ASTM D 2414-79) based on measured weight: about 170-290%.(g) linear average of numerical distribution of secondary particles: about 10-2,000 nm;(h) linear average of volume distribution of secondary particles: about 3-30 um;(i) proportion of secondary particles with a diameter of less than 1 um: about 0.01-5% by weightwherein the percentages of parameters (a) to (c), added up together, must yield 100% by weight.

Abstract: Polyamide powder coating compositions for the coating of metals at high temperatures are obtained by the precipitation method from polyamides having at least 10 aliphatically bound carbon atoms per carbonamide group, copolyamides having at least 70% of these polyamides and mixtures of homopolyamides and copolyamides having at least 70% of these polyamides.A. For the preparation of powder coating compositions useful in the fluidized bed coating method the polyamides with 10 or more carbon atoms and having a relative viscosity between 1.4 and 1.8 are added to at least twice the amount by weight of ethanol and while the mixture is being mechanically mixed in a closed vessel is converted into a solution at temperatures between 130.degree. and 150.degree. C. This solution is adjusted to a precipitation temperature of between 100.degree. and 125.degree. C. while avoiding the formation of local sub-cooling and is agitated under an inert gas atmosphere to suppress boiling.