COMPOSITIONS BASED ON POLYAMIDES AND GLASS FIBERS AND USE THEREOF IN THE MEDICAL FIELD
The present invention relates to a molding composition comprising, by weight: a) 20% to 60%, especially from 20% to 50%, in particular 25% to 39.9%, of at least one long-chain aliphatic polyamide having a number of carbon atoms per nitrogen atom of greater than or equal to 9, in particular greater than or equal to 10, said at least one polyamide having an inherent viscosity in solution of less than or equal to 1.3, in particular less than or equal to 1.25, as determined in accordance with the standard ISO 307:2007 at a temperature of 20° C., b) 40% to 75% of glass fibers, especially from 50% to 75%, in particular from 60% to 70%, of glass fibers, and c) 0% to 5% by weight, preferably 0.1% to 5% by weight, of at least one additive, the sum of the proportions of each constituent of said composition being equal to 100%.
1 . A molding composition comprising, by weight:
a) 20% to 60% of at least one long-chain aliphatic polyamide having a number of carbon atoms per nitrogen atom of greater than or equal to 9, said at least one polyamide having an inherent viscosity in solution of less than or equal to 1.3, as determined in accordance with the standard ISO 307:2007 at a temperature of 20° C.,
b) 40% to 75% of glass fibers, said glass fibers being short glass fibers of circular cross section and having a fiber length of from 120 to 350 μm, and
c) 0% to 5% by weight of at least one additive, the sum of the proportions of each constituent of said composition being equal to 100%.
2 . The composition as claimed in claim 1 , wherein at least two long-chain aliphatic polyamides are present in the composition.
3 . The composition as claimed in claim 1 , wherein the long-chain aliphatic polyamide is obtained by polycondensation:
of at least one C 9 to C 18 amino acid, or of at least one C 9 to C 18 lactam, or of at least one aliphatic diamine Ca of at least one C 4 -C 36 diamine Ca with at least one C 4 -C 36 dicarboxylic acid Cb, or a mixture thereof.
4 . The composition as claimed in claim 1 wherein the long-chain aliphatic polyamide is obtained by polycondensation:
of at least one C 9 to C 18 amino acid, or of at least one C 9 to C 18 lactam.
5 . The composition as claimed in claim 1 , wherein said long-chain polyamide is chosen from PA1010, PA1012, PA1212, PA11 and PA 12.
6 . The composition as claimed in claim 1 , wherein said long-chain polyamide is chosen from PA11 and PA 12.
7 . The composition as claimed in claim 1 , wherein said at least one additive is chosen from fillers, dyes, stabilizers, plasticizers, surface-active agents, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, additives for laser marking, and mixtures thereof.
8 . A method for the manufacture of an article for the medical field, the method comprising manufacturing the article from the composition as defined in claim 1 .
9 . The method as claimed in claim 8 , wherein the article for the medical field is a surgical instrument.
10 . The method as claimed in claim 9 , wherein the article after steam sterilization exhibits a variation in cross section of less than 3% compared to the cross section before sterilization, determined on a type 1A test specimen.
11 . The method as claimed in claim 9 , wherein the article exhibits very good resistance to gamma-ray sterilization.
12 . The method as claimed in claim 10 , wherein the article after steam sterilization exhibits a variation in stress of less than 20% compared to the breaking stress before sterilization, determined in accordance with the standard ISO 527:2012 on a type 1A test specimen.
13 . The method in claim 8 , wherein the article is manufactured by injection molding.
14 . An article obtained by injection molding with a composition as defined in claim 1 .