GB1590528A

GB1590528A - Polyamides

Info

Publication number: GB1590528A
Application number: GB3154377A
Authority: GB
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1976-08-04
Filing date: 1977-07-27
Publication date: 1981-06-03
Also published as: IT1079370B; NL7708388A; FR2360621B1; DE2635085A1; GB1590529A; CH631727A5; FR2360621A1; JPS5318697A; GB1590530A

Abstract

Copolyamides comprising A) 50-99.9 mol% of units of the structure <IMAGE> and optionally <IMAGE>, B) 50-0.1 mol% of units of the structure <IMAGE> and optionally <IMAGE>, where R is 1) the radical of at least one cycloaliphatic diamine of the formula <IMAGE> where y is 0 or an integer from 1 to 3, and x is 0 or 1, and/or 2) the radical of bis(aminocyclohexyl)alkanes of the formula <IMAGE> where R' is hydrogen or methyl, it being possible for the two R' radicals to be identical or different, and/or 3) the radical of a heterocyclic amine of the formula <IMAGE> where R'' is methyl or ethyl, and the R'' radicals may be identical or different, and Z is 0 or an integer from 1 to 2, are obtained by first heating the mixture of isophthalic acid and optionally terephthalic acid and hexamethylenediamine and at least one of said diamines to temperatures between 190 DEG C and 230 DEG C, and, when this precondensation is complete, polycondensing the mixture to completion at temperatures between 240 DEG C and 300 DEG C. The resultant copolyamides can be used for the production of mouldings, such as fibres, films, sheets and injection mouldings.

Description

(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:- This invention relates to copolyamides of isophthalic acid, hexamethylene diamine and certain cyclic aliphatic diamines.

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

Patent Nos. 2,715,620 and 2,742,496) but because of their insufficient dimensional stability at elevated temperatures and their insufficient glass transition temperature 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 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 cyclic aliphatic diamines.

The present invention therefore relates to copolyamides consisting essentially of from 50 to 99.9 mol %, preferably 60 to 90 mol %, of units (A) having the structure:

and from 50 to 0.1 mol %, preferably 40 to 10 mol %, of units (B) having the structure:

wherein R denotes (1) a cycloaliphatic diamine group of the formula:

wherein x represents 0 or 1, and optionally (2) a bis-(aminocyclohexyl)-alkane group of the formula:

wherein R' denotes hydrogen or methyl, the two radicals R' being the same or different, and optionally (3) a heterocyclic amine group of the formula

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 %.

Preferably, from 50 to 100 mol % of the groups R are as defined above under (1).

Similar copolyamides wherein R is as defined above under (2) and (3) respectively are described and claimed in our copending divisional Applications Nos. 79 17534 (Serial No. 1,590,529) and 79 17535 (Serial No. 1,590,530).

The copolyamides are generally prepared by heating the mixture of isophthalic acid, hexamethylene diamine and at least one of the above mentioned diamines first to temperatures of between 1900C 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 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 other diamines.

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

Any loss in diamine occurring during polycondensation is compensated by using an appropriate excess of hexamethylene diamine.

The cyclic aliphatic diamines used can be selected from e.g. 1,4-diamino- cyclohexane and 4-aminomethylcyclohexylamine, and optionally bis-(aminocyclohexyl)-alkanes having from 13 to 15 C-atoms, e.g. bis-(4-amino-cyclohexyl)methane or bis-(4-aminocyclohexyl)-propane, or heterocyclic diamines having 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 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 250C in an Ubbelohde-Viskosimeter, is > 2. The copolyamides are transparent and can easily be processed thermoplastically. They may contain auxiliary agents and additives, 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.

Example 1.

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 with the addition of 0.84 g (2% by weight, based on the proportion of hexamethylene diamine originally put into the process) of hexamethylene diamine under an atmosphere of nitrogen with stirring, first to 2200 C for two hours and then to 2700C 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 250C in an Ubbelohde-Viskosimeter.

The glass transition 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 1,4-diaminocyclohexane were determined by differential thermoanalysis. The results are summarised in the Table below.

Molar ratio of hexamethylene diamine: Glass transition temperature 1,4-diaminocyclohexane ( C) 100 : 0 130 99 : 1 132 95 : 5 135 90 : 10 143 85 : 15 148 80 : 20 149 Example 2.

Comparison Example A mixture of the salt of isophthalic acid and hexamethylene diamine and of the salt of terephthalic acid and hexamethylene diamine is polycondensed as described in Example 1. The loss of diamine is compensated by the addition of 2% by weight of hexamethylene diamine (based on the quantity of hexamethylene diamine originally put into the process). The molecular weight is controlled by the addition of 0.5 mol of benzoic acid (based on 100 mol of salt). The following Table shows the dependence of the glass transition temperature on the ratio of isophthalic acid to terephthalic acid in the mixture.

Molar ratio of isophthalic acid: Glass transition temperature terephthalic acid ( C) 60 : 40 133 70 : 30 132 75 : 25 132 85 : 15 132 95 : 5 132 Example 3.

Transparent copolyamides of isophthalic acid, hexamethylene diamine and 4aminomethyl-cyclohexylamine were prepared as in Example 1 with varying molar ratios of the diamine components. The glass transition temperature of the polyamides are set forth in the following Table.

Molar ratio of hexamethylene diamine: Glass transition temperature 4-aminomethyl-cyclohexylamine ( C) 90 : 10 140 80 : 20 150 Example 4.

A transparent copolyamide was prepared from isophthalic acid, hexamethylene diamine, 1,4-diaminocyclohexane and bis-(4-aminocyclohexyl)methane. Polycondensation was carried out for two hours at 2200C and three hours at 2700C in a nitrogen atmosphere with stirring. The molar ratio of the diamines or salts to isophthalic acid was 80:10:10 respectively. The copolyamide had a glass transition temperature of 153"C.

In the present specification and claims, the rings in the formulae are unsubstituted except for any specific substituents indicated.

WHAT WE CLAIM IS: 1. Transparent copolyamides consisting essentially of from 50 to 99.9 mol % of units (A) having the structure:

and from 50 to 0.1 mol % of units (B) having the structure:

wherein R denotes

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

Molar ratio of isophthalic acid: Glass transition temperature terephthalic acid ( C) 60 : 40 133 70 : 30 132 75 : 25 132 85 : 15 132

95 : 5 132 Example 3.

Transparent copolyamides of isophthalic acid, hexamethylene diamine and 4aminomethyl-cyclohexylamine were prepared as in Example 1 with varying molar ratios of the diamine components. The glass transition temperature of the polyamides are set forth in the following Table.

Molar ratio of hexamethylene diamine: Glass transition temperature 4-aminomethyl-cyclohexylamine ( C) 90 : 10 140 80 : 20 150 Example 4.

A transparent copolyamide was prepared from isophthalic acid, hexamethylene diamine, 1,4-diaminocyclohexane and bis-(4-aminocyclohexyl)methane. Polycondensation was carried out for two hours at 2200C and three hours at 2700C in a nitrogen atmosphere with stirring. The molar ratio of the diamines or salts to isophthalic acid was 80:10:10 respectively. The copolyamide had a glass transition temperature of 153"C.

In the present specification and claims, the rings in the formulae are unsubstituted except for any specific substituents indicated.

WHAT WE CLAIM IS: 1. Transparent copolyamides consisting essentially of from 50 to 99.9 mol % of units (A) having the structure:

and from 50 to 0.1 mol % of units (B) having the structure:

wherein R denotes

(1) a cycloaliphatic diamine group of the formula:

wherein x represents 0 or 1, and optionally (2) a bis-(aminocyclohexyl)-alkane group of the formula:

wherein R' denotes hydrogen or methyl, the two radicals R' being the same or different, and optionally (3) a heterocyclic amine group of the formula

wherein R" denotes methyl or ethyl, the radicals R" being the same or different, and z represents 0, 1 or 2, the sum of (A) and (B) being 100%.
2. Copolyamides as claimed in Claim 1, consisting essentially of from 60 to 9a mol % of units having the structure (A) and from 40 to 10 mol % of units having the structure (B).
3. Copolyamides as claimed in Claim 1, wherein R is derived from 1,4diaminocyclohexane or 4-aminomethyl-cycldhexylamine, and optionally bis-(4aminocyclohexyl)-methane, bis-(4-aminocyclohexyl)-propane or piperazine.
4. A copolyamide according to claim 1, substantially as herein described with reference to any of the Examples.
5. A process for preparing a copolyamide according to claim 1, which comprises condensing, in the required proportions, isophthalic acid, hexamethylene diamine and a diamine corresponding to the group R, optionally in the form of their salts.
6. A process according to claim 5, wherein precondensation is carried out at a temperature of from 190 to 2300 C, and polycondensation is completed at a temperature of from 240 to 3000 C.
7. A process according to claim 5, substantially as herein described with reference to any of the Examples.
8. A copolyamide when prepared by a process according to any one of claims 5 to 7.
9. Shaped articles comprising a copolyamide according to any one of claims 1 to 4 and 8.