GB1590530A - Polyamides - Google Patents

Description

PATENT SPECIFICATION ( 11) 1590530

( 21) Application No 17535/79 ( 22) Filed 27 July 1977 ( 62) Divided out of No1 590 528 ( 19) ( 31) Convention Application No 2 635 085 O' ( 32) Filed 4 Aug 1976 in ( 33) Fed Rep of Germany (DE) ( 44) Complete Specification published 3 June 1981 ( 51) INT CL 3 C 08 G 69/26 ( 52) Index at acceptance C 3 R 22 C 22 D 1 A 2 22 D 1 B 2 22 D 2 A 2 22 D 2 B 3 22 M 7 22 N 1 B C 14 B C 22 C 23 C 24 C 33 B C 5 B 1 C 6 X SP C 3 Y B 262 B 263 B 270 B 284 B 285 G 220 G 310 G 315 G 330 H 600 ( 72) Inventors WERNER NIELINGER, BERT BRASSAT, HUGO VERNALEKEN and LUDWIG BOTTENBRUCH ( 54) POLYAMIDES ( 71) We, BAYER AKTIENGESELLSCHAFT, a body corporate organised under the laws of the Federal Republic of Germany, of 509 Leverkusen, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly

described in and by the following statement: 5

This invention relates to copolyamides of isophthalic acid, hexamethylene diamine and certain heterocyclic diamines.

Polyamides of isophthahlc acid and hexamethylene diamine are known (U S.

Patents Nos 2,715,620 and 2,742,496) but because of their insufficient dimensional stability at elevated temperatures and their insufficient glass transition temperature 10 they cannot be used for numerous applications It has therefore been proposed to solve this problem by preparing copolyamides with terephthalic acid.

Although the melting point of the products is thus raised, their glass transition temperature is not raised The glass transition temperature is the essential property determining the extent to which amorphous polymers can withstand thermal 15 stresses.

It has now surprisingly been found that the glass transition temperature of polyamides obtained from isophthalic acid and hexamethylene diamine can be raised by partially replacing the hexamethylene diamine with certain heterocyclic diamines 20 The present invention therfore relates to copolyamides consisting essentially of from 60 to 90 mol% of units (A) having the structure:

0 O C-N-(CH 2)6-NO o and from 40 to 10 mol% of units (B) having the structure:

2 Jo C-R 25 wherein R denotes a heterocyclic amine group of the formula:

I>_ Rle) z wherein R" denotes methyl or ethyl, the R radicals being the same or different, and z represents 0, 1 or 2, the sum of A and B being 100 mol% 5 The present application and our copending Application No 79 17534 (Serial No 1,590,529) are both divided from application No 31543/77 (serial No.

1,590,528) which describes and claims similar copolyamides in which R represents a cycloaliphatic diamine group of defined formula.

The copolyamides are generally prepared by heating the mixture of isophthalic 10 acid, hexamethylene diamine and at least one of the above mentioned diamines first to temperatures of between 190 C and 230 C After this precondensation, polycondensation is completed at temperatures of between 240 C and 300 C.

Precondensation may be carried out with or without the addition of water and it may be carried out at atmospheric pressure or under the vapour pressure of water 15 in sealed autoclaves.

The polycondensation is advantageously carried out using salts of the monomers.

The amine mixture is composed of 50 to 99 9 mol%, preferably 60 to 90 mol%, of hexamethylene diamine and 50 to 0 1 mol%, preferably 40 to 10 mol%, of the 20 other diamines.

The optimum proportion of hexamethylene diamine to heterocyclic diamines depends to some extent on the additional dimines used.

Any loss in diamine occuring during polycondensation is compensated by using an appropriate excess of hexamethylene diamine 25 The heterocyclic diamines used have from 4 to 8 C-atoms, e g piperazine.

Up to 10 mol%, preferably up to 5 mol%, of the isophthalic acid can be substituted by terephthalic acid without changing the properties of the copolyamide substantially.

The molecular weight of the polyamides can be controlled by means of 30 carboxylic acids or amines, preferably benzoic acid or sebacic acid.

The relative solution viscosity of the copolyamides according to the invention, determined on a 1 % by weight solution of the polyamide in m-cresol at 25 C in an Ubbelohde-Viskosimeter, is > 2 The copolyamides are transparent and can easily be processed thermoplastically They may contain auxiliary agents and additives, 35 for example lubricants, mould release agents, dyes, glass fibres, fillers or flameretarding agents The copolyamides may be used for the manufacture of shaped products with improved dimensional stability at elevated temperatures and improved glass transition temperatures such as fibres, sheets, plates or injectionmoulded articles 40 Example 1.

(Reference Example, according to Parent Application) 101 6 g ( 0 36 mol) of a salt of hexamethylene diamine and isophthalic acid and 11 21 g ( 0 04 mol) of a salt of 1,4-diaminocyclohexane and isophthalic acid are heated under the addition of 0 84 g ( 2 % by weight, based on the proportion of 45 hexamethylene diamine originally put into the process) of hexamethylene diamine under an atmosphere of nitrogen with stirring, first to 220 C for two hours and then to 270 C for three hours A transparent copolyamide is obtained It has a relative solution viscosity of 3 1, determined on a 1 % by weight solution of the polyamide in -m-cresol at 25 C in an Ubbelohde-Viskosimeter 50 The glass transistion temperature of this copolyamide as well as that of several other transparent copolyamides which were prepared in a similar manner but with a different molar ratio of hexamethylene diamine to 1,4diaminocyclohexane were determined by differential thermoanalysis The results are summarised in the Table below 55 1,590,530 1,590,530 Molar ratio of hexamethylene diamine:

1,4-diaminocyclohexane 100:0 99:1 95:5 90:10 85:15 80:20 Glass transition temperature ( C) 132 143 148 149 Example 2.

A transparent copolyamide of isophthalic acid, hexamethylene diamine and piperazine was prepared as in Example 1 and the glass transition temperature was determined by differential thermoanalysis.

Molar ratio of hexamethylene diamine:

piperazine 90:10 Glass transition temperature ( C)

Claims (2)

WHAT WE CLAIM IS:-

1.590530

1 Transparent copolyamides consisting essentially of from 60 to 90 mol% units (a) having the structure:

0 i H -C C-N-(CH 2)6-Nfrom 40 to 10 mol% of units (B) having the structure:

wherein R denotes a heterocyclic amine group of the formula:

and 7 15 790 30 wherein R" denotes methyl or ethyl, the radicals R" being the same or different, and z re Dresents 0 1 or

2.

the sum of (A) and (B) being 100 % 5 2 Copolyamides as claimed in Claim I, wherein R is derived from piperazine.

3 A copolyamide according to claim 1, substantially as herein described with reference to Example 2.

4 A process for preparing a copolyamide according to claim 1, which comprises condensing, in the required proportions, isophthalic acid, 10 hexamethylene diamine and a diamine corresponding to the group R, optionally in the form of their salts.

A process according to claim 4, wherein precondensation is carried out at a temperature of from 190 to 230 C, and polycondensation is completed at a temperature of from 240 to 300 C 15 6 A process according to claim 4, substantially as herein described with reference to Example 2.

7 A copolyamide when prepared by a process according to any one of claims 4 to 6.

8 Shaped articles comprising a copolyamide according to any one of claims 1 20 to 3 and 7.

ELKINGTON & FIFE, Chartered Patent Agents, Agents for the Applicants, High Holborn House, 52/54 High Holborn, London WC 1 V 65 H Printed for Her Mfajesty's Stationery Office by the Courier Press, Leamington Spa, 1981.

Published by the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.