Polyamide moulding composition, in particular for the production of mouldings in the drinking water sector

Abstract

A polyamide moulding composition in particular for use for components in the drinking water sector, made of the following constituents:(A) from 25 to 74.9% by weight of at least one semicrystalline, semiaromatic nylon-6,T / 6,I, composed of: (a1) from 65 to 82 mol % of terephthalic acid, based on the entirety of the dicarboxylic acids used; (a2) from 18 to 35 mol % of isophthalic acid, based on the entirety of the dicarboxylic acids used; (a3) 1,6-diaminohexane; (a4) at least one monobasic carboxylic acid; (a5) a phosphorus compound; with the first proviso that the molar ratio of the component (a3) to the entirety of the dicarboxylic acids used ((a1)+(a2)) is at least 1.04 and at most 1.15; and with the second proviso that the molar ratio of the component (a4) to the component (a3) is in the range from 0.01 to 0.08;(B) from 25 to 60% by weight of fibrous reinforcing materials;(C) from 0 to 30% by weight of particulate fillers;(D) from 0.1 to 2.0% by weight of heat stabilizers, with the proviso that no copper-containing stabilizers are present therein;(E) from 0 to 2% by weight of carbon black;(F) from 0 to 4% by weight of auxiliaries and / or additives differing from C, D and E; where the entirety of the components (A)-(F) makes up 100% by weight.

Description

TECHNICAL FIELD[0001]The present invention relates to a polyamide moulding composition, in particular for use in the drinking water sector, i.e. for the production of mouldings with improved performance in the long-term failure test under internal hydrostatic pressure at temperatures above room temperature, and where the processed moulding composition comes into contact with drinking water during correct use.PRIOR ART[0002]Semicrystalline semiaromatic polyamides or copolyamides were developed for use in high-temperature environments and, in particular with a content of at least 50 mol % of semialiphatic terephthalamide units, feature particularly good thermo-mechanical properties. The melting point of polyamides of this type is typically in the range from 270 to 330° C.[0003]Demanding applications in the sanitary sector and in particular in contact with drinking water moreover require high bursting pressure and high performance in the long-term failure test under internal hydrostati...

AI Technical Summary

Benefits of technology

The invention is about thermoplastic molding compositions that can be used to make molded objects that can withstand high temperatures and pressures, and are stable when exposed to warm water or food. These compositions can be used for applications such as water meters, valves, and parts for tea and coffee machines. They are also suitable for use in heating and cooling systems, including those used in automobiles. The technical effect is the production of molded objects that can withstand high temperatures and pressures, and are stable when exposed to warm water or food.

Problems solved by technology

However, when the mixtures of the invention, based on PA66 and on amorphous PA 6I / 6T (with a high proportion of 6I units), are in contact with water at 80° C., they do not have the strength or bursting pressure or performance in the long-term failure test under internal hydrostatic pressure that would lead to suitability and approval for drinking-water applications at high temperature and high pressure.

Other documents in turn say that certain upper or lower limits are necessary for terminal amino groups and terminal carboxy groups, but these do not provide any coherent picture in the context of improvement of the stability of semiaromatic polyamides in contact with water.