Arkema France

Gregory Filou

Cyrille Mathieu

Holger Senff

Arnaud Lemaitre

A method for reducing the crystallization temperature and the melting temperature of a polyamide powder resulting from the polymerization of at least one predominant monomer, in which the reduction in the crystallization temperature is greater than the reduction in the melting temperature, the method including a step of polymerization of the at least one predominant monomer with at least one different minor comonomer polymerized according to the same polymerization process as the at least one predominant monomer, the at least one minor comonomer being chosen from aminocarboxylic acids, diamine/diacid pairs, lactams and/or lactones, and the at least one minor comonomer representing from 0.1% to 20% by weight of the total blend of the monomers(s) and comonomer(s), preferably from 0.5% to 15% by weight of the total blend, preferably from 1% to 10% by weight of the total blend.

Method for increasing the difference between the melting temperature and the crystallization temperature of a polyamide powder

The present invention relates to a method for reducing the crystallization temperature an the melting temperature of a polyamide powder resulting from the polymerization of at least one predominant monomer, in which the reduction in the crystallization temperature is greater than the reduction in the melting temperature, said method comprising a step of polymerization of said at least one predominant monomer with at least one different minor comonomer polymerized according to the same polymerization process as said at least one predominant monomer, said at least one minor comonomer being chosen from aminocarboxylic acids, diamine/diacid pairs, lactams and/or lactones, and said at least one minor comonomer representing from 0.1% to 20% by weight of the total blend of said monomers(s) and comonomer(s), preferably from 0.5% to 15% by weight of said total blend, preferably from 1% to 10% by weight of said total blend.

A method for preparing a recyclable polyamide powder, including the following consecutive steps: a) a step of adding 0.01 to 5 wt % of at least one antioxidant in powder form to a mixture including 20 to 95 wt % of polyamide powder and 5 to 80 wt % of liquid, relative to the weight of said mixture, the polyamide powder having a pH in the range from 3 to 8 and a yellowness index of less than 4, measured according to standard ASTM E 313-05, D1925, the liquid being a non-solvent for polyamide at a temperature between 5&#xb0; C. and the boiling temperature Tof said liquid; b) a step of homogenizing the mixture obtained in step a); c) a step of recovering powder isolated from the liquid.

Method for preparing a recyclable polyamide powder

A subject-matter of the invention is the use of a polyamide powder possessing a fireproofing property in a process for the manufacture of an object made of polyamide by sintering this powder using radiation, the said powder comprising, by weight, 2 to 40% of at least one flame retardant for respectively 98 to 60% of at least one polyamide, the flame retardant being a blend of at least one organic phosphinate of a metal and of at least ammonium polyphosphate.

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Manneville sur Risle, France

Gregory Filou