Abstract: A process for continuously preparing copolyamides from lactams and salts of diamines and dicarboxylic acids, in which lactams together with salts of diamines and dicarboxylic acids are passed from the top downward through a vertical polymerization tube at polyamide-forming temperatures, which comprises a) intensively mixing an aqueous solution of lactams with salts of diamines and dicarboxylic acids under elevated pressure which is greater than the vapor pressure of the mixture which arises in a mixing apparatus at a temperature of from 80 to 300° C., b) feeding the mixture thus obtained to a heated helical tube evaporator in which a liquid phase and a vapor phase form at a temperature of from 140 to 300° C.

Abstract: The present invention relates to a process for preparing polyamides, comprising a hydrolytic polymerization and at least two extraction steps which are not in immediate succession.

Abstract: A process for continuously preparing copolyamides from lactams and salts of diamines and dicarboxylic acids, in which lactams together with salts of diamines and dicarboxylic acids are passed from the top downward through a vertical polymerization tube at polyamide-forming temperatures, which comprises a) intensively mixing an aqueous solution of lactams with salts of diamines and dicarboxylic acids under elevated pressure which is greater than the vapor pressure of the mixture which arises in a mixing apparatus at a temperature of from 80 to 300° C., b) feeding the mixture thus obtained to a heated helical tube evaporator in which a liquid phase and a vapor phase form at a temperature of from 140 to 300° C.

Abstract: A process for continuous extraction of polyamide particles in an essentially vertical extraction column using an aqueous extractant comprises using an extraction column that is divided into two zones and performing an extraction with a recirculating 15-40% strength by weight aqueous &egr;-caprolactam solution in the first zone and then with countercurrent water at a from 5 to 40° C. lower temperature in the second zone. The process provides for economical extraction of polyamides with a low level of monomers and oligomers.

Abstract: Radiation-curable binders which are obtained by reactingA) an amine/formaldehyde condensate having a molar ratio of formaldehyde to amino groups of from 1:1 to 2:1 withB) one or more esters, having a free hydroxyl group, of acrylic acid or of methacrylic acid with polyalcohols which contain from two to four alcoholic hydroxyl groups, from 0.1 to 0.3 hydroxyl equivalent of component B) being used per methylol equivalent of component A),in the presence of a strong acid are suitable for use in coating materials.

Abstract: In the Czochralski crucible pulling of crystal ingots, in particular those of silicon and having particularly large crystal diameters, the degree of filling of the crucible is kept approximately constant during the pulling process by continuously adding solid or liquid recharging material. According to the invention, the known disadvantages of thermal disturbances and the introduction of impurities and particles are overcome by a recharging system with a gas-tight seal, comprising additional crucible, stock container for semiconductor material and dopant having the appropriate feedlines and an exhaust gas line. In addition, the process makes possible a regulatable and separate recharging of dopant via the additional crucible.

Abstract: In the Czochralski crucible pulling of crystal ingots, in particular those of silicon and having particularly large crystal diameters, the degree of filling of the crucible is kept approximately constant during the pulling process by continuously adding solid or liquid recharging material. According to the invention, the known disadvantages of thermal disturbances and the introduction of impurities and particles are overcome by a recharging system with a gas-tight seal, comprising additional crucible, stock container for semiconductor material and dopant having the appropriate feedlines and an exhaust gas line. In addition, the process makes possible a regulatable and separate recharging of dopant via the additional crucible.