Process for the preparation of polyamide foam plastics

Claim 1

IN A PROCESS FOR PREPARING FOAMED POLYAMIDE MATERIALS BY AMINONICALLY POLYMERIZING LACTAM MONOMERS IN THE PRESENCE OF BLOWING AGENTS AND PORE-CONTROLLING AGENTS, THE IMPROVEMENT FOR CONTROLLING THE SIZE AND NUMBER OF PORES AND THE THICKNESS OF THE PARTITION WALLS TO PRODUCE A SUBSTANTIALLY UNIFORMED FOAMED MATERIAL CONSISTING ESSENTIALLY IN ADDING BEFORE POLYMERIZING THE COMBINATION OF (1) AT LAST ONE SUBSTANCE HAVING AN OPEN CELL STRUCTURE, AND BEING A MEMBER OF THE GROUP OF A. POROUS INORGANIC SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF EXPANDED PERLITE, EXPANDED VERMICULITE, PUMICE, LAVA AND SILICON DIOXIDE IN POROUS FORM, AND B. SYNTHETIC EXPANDED POROUS RESIN HAVING A MELTING OR SOFTENING TEMPERATURE HICH IS HIGHER THAN THE POLYMERIZATION TEMPERATURE OF THE SAID LACTAM MONOMERS TO BE POLYMERIZED, AND SELECTED FROM THE CLASS CONSISTING OF FOAMED UREA FORMALDEHYDE RESIN AND FOAMED PHENOL FORMALDEHYDE REIN. SAID POROUS SUBSTANCES HAVING A PARTICLES SIZE RANGING BETWEEN ABOUT 60 AND 110 MESH AND PRESENT IN SAID LACTAMS MONOMERS TO BE POLYMERIZED IN A QUANTITY OF ABOUT 0.1 TO 2 WEIGHT %; AND (2) AT LEAST ONE ORGANOSILOXANE PRESENT IN SAID LACTAMS MONOMERS TO BE POLYMERIZED IN A QUANTITY OF ABOUT 0.1 TO 1.5 WEIGHT %.