Polyesters prepared from NH containing carboxylic acids

Linear thermoplastic polyesters obtained from (a) dicarboxylic acids which contain NH groups, (b) if desired, terephthalic acid and/or isophthalic acid, (c) if desired, diols containing aliphatic diol groups and (d) .beta.-hydroxyalkylated bisphenols are materials from which it is possible to produce shaped articles which have good properties, for example good resistance to stress cracking and stability to thermooxidative degradation, and also a low absorption of water.

The present invention relates to polyesters obtained from dicarboxylic 
acids which contain NH groups, if desired terephthalic acid and/or 
isophthalic acid, a .beta.-hydroxyalkylated bisphenol and, if desired, 
further diols containing aliphatic diol groups. 
Polyesters and copolyesters with s-triazinedicarboxylic acids are described 
in German Offenlegungsschriften Nos. 2,533,675 and 2,533,715. Copolyesters 
which contain dicarboxylic acid diamides are described in German 
Offenlegungsschrift No. 2,414,349. These polyesters which contain NH 
groups have the disadvantage that their stability to thermooxidative 
degradation is relatively low and that they possess a relatively high 
capacity for water absorption. Because of their low resistance to stress 
cracking, their field of application is limited. 
The object of the present invention is to provide polyesters which contain 
NH groups (polyester-amides), which show a lower absorption of water and 
have improved stability to thermooxidative degradation and resistance to 
stress cracking, without this resulting in a deterioration of the 
mechanical properties. 
The present invention relates to linear thermoplastic polyesters which have 
a relative viscosity of at least 1.30, measured on a solution of 1 g of 
polyester in 100 ml of a solvent consisting of equal parts of phenol and 
symmetrical tetrachloroethane at 30.degree. C., and consist, relative to 
the polyester, of (a) 25-50 mol % of at least one dicarboxylic acid which 
contains NH groups and is of the general formula I 
EQU hooc--a--(co).sub.n --NH--X--NH--(CO).sub.n --A--COOH (I) 
in which A represents o-, m- or p-phenylene and 1,4- or 1,6-naphthylene 
and, when n=O, X represents a radical of the formula II 
##STR1## 
in which R represents methyl, ethyl, cyclohexyl or phenyl, or, when n=1, X 
represents a divalent hydrocarbon radical of aliphatic or aromatic 
character, (b) 25-0 mol % of terephthalic acid and/or isophthalic acid and 
(c) 0 to 25 mol % of one or more diols containing aliphatic diol groups, 
wherein (d) 50-25 mol % of at least one bisphenol derivative of the 
general formula III 
##STR2## 
in which R.sup.1 represents a hydrogen atom, methyl or ethyl, R.sup.2 
represents a hydrogen, chlorine or bromine atom or methyl and Y represents 
substituted or unsubstituted alkylene, alkylidene or cycloalkylidene, a 
direct bond, O, S or SO.sub.2, have been co-condensed as a diol containing 
aliphatic diol groups. 
Preferably, the relative viscosity of the polyesters is 1.5-3.5. 
Preferably, the polyester consists to the extent of 40-50 mol %, and 
especially 50 mol %, of the dicarboxylic acids (a), to the extent of 10-0 
mol % of the dicarboxylic acids (b), to the extent of 10-0 mol % of the 
diols (c) and to the extent of 40-50 mol %, and especially 50 mol %, of 
the diols (d). 
In formula I, A preferably represents m-phenylene and especially 
p-phenylene. 
The triazinedicarboxylic acids of the formula I, in which R in formula II 
preferably represents ethyl and phenyl, are described in German 
Offenlegungsschrift No. 2,121,184. 
The dicarboxylic acid diamides of the formula I are known from German 
Offenlegungsschrift No. 2,414,349. In these compounds, X, as a divalent 
hydrocarbon radical, preferably represents linear or branched alkylene 
having, especially, 2 to 6 C atoms and especially represents substituted 
or unsubstituted cycloalkylene, alkylcycloalkylene, 
alkylcycloalkylenealkyl, arylene, alkylarylene or alkylarylenealkyl, which 
preferably contain a total of 5 to 15 C atoms. Cycloalkylene preferably 
contains 5 to 7 ring members and arylene is preferably phenylene. The 
alkylene groups in the cyclic radicals contain preferably 1 to 4 and 
especially 1 to 2 C atoms and in particular 1 C atom. 
Examples of X as alkylene are methylene, ethylene, 1,2- and 1,3-propylene, 
1,2-, 1,3- and 1,4-butylene, pentylene, hexylene and dodecylene. 
Examples of divalent aromatic hydrocarbon radicals are: p- and m-phenylene, 
p- and m-tolylene, p- and m-xylylene, 1-methylenephenyl and 1,3- or 
1,4-bis-methylene-benzene. 
Examples of suitable cycloaliphatic and cycloaliphatic-aliphatic divalent 
radicals are: 3-methylene-3,5,5-trimethyl-1-cyclohexyl (isophorone); 
bis-(3-methylcyclohexylene-4)-methane, 2,2-bis-(p-cyclohexylene)-propane, 
bis-(p-cyclohexylene)-methane, 1,8-menthylene, 2-methylene-cyclopentyl, 
1,3-cyclohexylene, 1,4-cyclohexylene, 2-methyl-1,3-cyclohexylene, 
2-methyl-1,4-cyclohexylene, 1,3-cyclopentylene, 1,3-cycloheptylene, 
1,4-cycloheptylene, 1-methylenecyclohexyl and 
1,4-bis-methylenecyclohexane. 
X in formula I is preferably phenylene, cyclohexylene or a radical of the 
formulae 
##STR3## 
The polyesters can also contain diols (c) having aliphatic diol groups. 
Examples of such diols are linear or branched alkylene-diols having 
preferably 2 to 12 and especially 2 to 6 C atoms. The alkylenediol is 
especially ethylene glycol or tetramethylene glycol. 1,4-Cyclohexanediol 
and 1,4-di-hydroxymethyl-cyclohexane may also be mentioned. 
A further group of diols (c) having aliphatic diol groups are those of the 
general formula IV 
##STR4## 
in which R.sup.3 represents methyl or preferably represents a hydrogen 
atom and Z represents a radical of the formulae V-Vc 
##STR5## 
in which R.sup.4, R.sup.5 and R.sup.6 independently of one another 
represent alkyl having 1 to 4 C atoms or together represent tetra- or 
penta-methylene and the R.sup.7 independently of one another represent a 
hydrogen, chlorine or bromine atom. 
The diols of the formula IV are known and are described, for example, in 
German Offenlegungsschriften Nos. 1,812,003, 2,342,432, 2,342,372 and 
2,453,326. Examples are: 
N,N'-bis-(.beta.-hydroxyethyl-5,5-dimethyl)-hydantoin, 
N,N'-bis-(.beta.-hydroxypropyl-5,5-dimethyl)-hydantoin, 
methylene-bis-[N,N'-(.beta.-hydroxyethyl)-5-methyl-5-ethylenehydantoin], 
methylene-bis-[N-(.beta.-hydroxyethyl)-5,5-dimethylhydantoin], 
N,N'-bis-(.beta.-hydroxyethyl)-benzimidazolone, 
-(tetrachloro)-benzimidazolone or -(tetrabromo)-benzimidazolone. 
Preferably, in formula IV, R.sup.3 represents a hydrogen atom, R.sup.4, 
R.sup.5 and R.sup.6 represent methyl and all the R.sup.7 represent either 
a hydrogen atom, a chlorine atom or a bromine atom. 
In the diols (d), R.sup.1 in formula III preferably represents methyl and 
especially represents a hydrogen atom. R.sup.2 is, furthermore, preferably 
bonded in the two ortho-positions relative to the oxygen atom. In 
particular, R.sup.2 represents a hydrogen atom. 
Examples of substituted or unsubstituted alkylene are: methylene, ethylene, 
phenylmethylene, diphenylmethylene and methylphenylmethylene. 
Examples of substituted or unsubstituted alkylidene are: ethylidene, 1,4- 
or 1,2-propylidene, butylidene, 1,1-dichloroethylidene or 
1,1,1-trichloroethylidene. 
Examples of cycloalkylidene are: cyclopentylidene, cyclohexylidene, 
cycloheptylidene and cyclooctylidene. 
The diols of the formula II are obtained by reacting corresponding 
bisphenols with ethylene oxide, propylene oxide or butylene oxide. 
Examples of bisphenols are: bis-(p-hydroxyphenyl)ether or thioether, 
bis-(p-hydroxyphenyl)-sulphone, bis-(p-hydroxyphenyl)-methane, 
1,2-bis-(p-hydroxyphenyl)-ethane, phenyl-bis-(p-hydroxyphenyl)-methane, 
diphenyl-bis-(p-hydroxyphenyl)-methane, 
2,2-bis-(4'-hydroxy-3'-methylphenyl)-propane, 
2,2-bis-(4'-hydroxy-3',5'-dimethylphenyl)-propane, 
2,2-bis-(4'-hydroxy-3'-chlorophenyl)-propane, 
2,2-bis-(4'-hydroxy-3',5'-dichlorophenyl)-propane, 
2,2-bis-(4'-hydroxy-3',5'-dibromophenyl)-propane, 1,1- or 
2,2-bis-(p-hydroxyphenyl)-butane, 1,1-dichloro- or 
1,1,1-trichloro-2,2-bis-(p-hydroxyphenyl)-ethane and 
1,1-bis-(p-hydroxyphenyl)-cyclopentane and especially 
2,2-bis-(p-hydroxyphenyl)-propane (bisphenol A) and 
1,1-bis-(p-hydroxyphenyl)-cyclohexane (bisphenol C). 
A particularly preferred diol from this group is 
2,2-bis-[4'-(.beta.-hydroxyethyl)-phenyl]-propane. 
The polyesters according to the invention are obtained according to known 
processes by subjecting the dicarboxylic acids, or thereof 
polyester-forming derivatives to a polycondensation reaction with one or 
more diols containing aliphatic alcohol groups at temperatures of 
50.degree. to 320.degree. C., under normal pressure, in vacuo and/or in a 
stream of inert gas, until the desired viscosity is reached. 
The known processes for the preparation of the novel polyesters are, for 
example, solution condensation or azeotropic condensation, interfacial 
condensation, melt condensation or solid phase condensation as well as 
combinations of these methods, depending on which polyester-forming 
derivatives and reaction catalysts are used. Solid phase condensation can 
also be carried out in thin layers, if necessary with the aid of a solid 
parting agent, for example micromica, talc, titanium dioxide or glass 
balls. 
Polyester-forming derivatives of the dicarboxylic acids which are used are, 
in the main, the low-molecular dialkyl esters having 1 to 4 carbon atoms 
in the molecule, preferably the dimethyl esters or diphenyl esters. 
Furthermore, the acid dihalides, especially the acid dichlorides, and the 
mixed anhydrides obtained from the dicarboxylic acids and low-molecular 
aliphatic monocarboxylic acids are also suitable. 
In one embodiment, the polyesters according to the invention can be 
prepared by esterifying or transesterifying the dicarboxylic acid, or 
several dicarboxylic acids, or their low-molecular dialkyl esters, with 
diols having aliphatic alcohol groups, at 150.degree.-250.degree. C. in an 
inert atmosphere, for example a nitrogen atmosphere, in the presence of 
catalysts and while at the same time removing the water or alkanol formed, 
and subsequently carrying out the polycondensation reaction at 200.degree. 
to 320.degree. C. and under reduced pressure in the presence of specific 
catalysts until the polycondensation products have the desired viscosity. 
After it has been removed from the reaction vessel and cooled, the 
resulting polyester melt is granulated or broken into chips in a 
conventional manner. 
Esterification catalysts which can be used are, in a known manner, amines 
and inorganic or organic acids, for example hydrochloric acid or 
p-toluenesulphonic acid, or, alternatively, metals or metal compounds 
which are suitable as transesterification catalysts. 
Since some catalysts preferentially accelerate transesterification and 
others preferentially accelerate the polycondensation reaction, a 
combination of several catalysts is advantageously used. Examples of 
suitable transesterification catalysts are the oxides, salts or organic 
compounds of the metals calcium, magnesium, zinc, cadmium, manganese, 
titanium and cobalt. It is also possible to use the metals themselves as 
catalysts. The polycondensation reaction is catalysed, for example, by 
metals such as lead, titanium, germanium and, especially, antimony or tin, 
and the compounds thereof. These catalysts can be added together or 
separately to the reaction mixture. These catalysts are employed in 
amounts of about 0.001 to 1.0 percent by weight, relative to the acid 
component. 
Those catalysts which accelerate both the transesterification and the 
polycondensation reaction are particularly advantageously used in the 
preparation of the polyesters according to the invention. Possible 
catalysts of this type are, in particular, mixtures of different metals or 
metal compounds and also corresponding metal alloys. 
Another embodiment for the preparation of the novel polyesters consists in 
subjecting one or more dicarboxylic acid dihalides, preferably the acid 
dichlorides, to a polycondensation reaction with diols containing 
aliphatic alcohol groups, in the presence of a basic catalyst, in the 
temperature range from 0.degree. to 100.degree. C., with the elimination 
of hydrogen halide. The basic catalysts used are preferably amines or 
quaternary ammonium salts. The proportion of basic catalyst can be from 
0.1 to 100 mol %, relative to the acid halides. This process can also be 
carried out without a solvent, or in the presence of a solvent. 
The polycondensation reaction can also be carried out by first subjecting 
the starting compound to a condensation reaction in the melt until a 
certain viscosity is reached, then granulating the precondensate prepared 
in this way for example with the aid of an underwater granulator, and 
drying the granules and then subjecting them to a solid phase condensation 
reaction, for which vacuum and temperatures below the melting point of the 
granules are employed. Higher viscosities can be achieved by this means. 
Inert additives of all types, such as fillers or reinforcing fillers, such 
as kaolin, metal powders, wollastonite, glass balls and, especially glass 
fibres, inorganic or organic pigments, optical brighteners, delustering 
agents, mould release agents, agents which promote crystallization and 
flameproofing agents, can be added to the reaction mass during working up 
of the polyester melt or even prior to the polycondensation reaction. 
If the polycondensation reaction is carried out discontinuously, the inert 
additives can already be added during the final condensation steps, for 
example during the solid phase condensation reaction or at the end of the 
melt condensation. 
The polyesters according to the invention are amorphous, depending on which 
diols and which dicarboxylic acids are used as the starting components and 
the ratios in which these are employed. The polyesters are colourless to 
yellow coloured and are thermoplastic materials (engineering plastics), 
from which mouldings having valuable properties can be produced by the 
conventional shaping processes, such as casting, injection moulding and 
extruding. Examples of such mouldings are components for technical 
equipment, apparatus casings, household equipment, sports equipment, 
electrical insulations, car components, circuits, sheets, films and 
semi-finished products which can be shaped by machining. It is also 
possible to use the polyesters for coating articles by known powder 
coating processes and for the production of fibres. 
The polyesters according to the invention are surprisingly more stable to 
thermooxidative degradation and resistant to stress cracking. The 
absorption of water is also suprisingly lower. The mechanical properties 
are only slightly changed. The reduction in the notched impact strength on 
warm storage is also substantially less. The combustibility is 
surprisingly reduced. 
The polyesters prepared according to the examples which follow are 
characterised in more detail by the following identifying data. The 
polyesters are characterised by those morphological changes which are 
measured by means of differential thermal analysis on a sample which has 
been heat-treated at 30.degree. C. above the melting point or above the 
softening point for 3 minutes and then rapidly chilled. The chilled sample 
is heated at a heating rate of 16.degree. C./minute by means of a "DSC-1B" 
differential scanning calorimeter from Messrs. Perkin-Elmer. The 
thermogram of the sample shows the glass transition temperature (T.sub.g), 
the crystallisation temperature (T.sub.c) and the crystallite melting 
point (T.sub.m). 
The glass transition temperature is given as the turning point at the 
sudden increase in the specific heat in the thermogram, the 
crystallisation temperature is given as the apex of the exothermic peak, 
the melting point is given as the apex of the endothermic peak and the 
decomposition temperature (T.sub.d) is given as that point at which the 
sudden exothermic and endothermic variations in the specific heat start. 
The relative viscosity of the polycondensation products of the examples is 
determined on solutions of 1 g of polyester in 100 ml of a mixture 
consisting of equal parts of phenol and symmetrical tetrachloroethane, at 
30.degree. C. The softening temperature (T.sub.s) is determined on a 
Kofler heated stage microscope at a heating rate of 15.degree. C./minute, 
a cross being formed from 2 filaments and the softening point being 
designated as that temperature at which the sharp angles of the cross 
disappear.

The examples which follow serve to illustrate the invention further. In 
these examples, parts are parts by weight. 
EXAMPLE 1 
248 parts of N,N'-bis-(4-carbomethoxybenzoyl)-isophoronediamine (compound 
A) and 158 parts of 2,2-bis-[4'-(.beta.-hydroxy-ethoxy)-phenyl]-propane (D 
22) and 0.146 part of isopropyl titanate are filled into a 2 liter reactor 
fitted with a stirrer, a nitrogen inlet, a condenser and a device for 
measuring the temperature. 97% of the amount of methanol theoretically to 
be expected is distilled off in the course of 2 hours and 15 minutes, 
whilst stirring and passing nitrogen through the mixture, and during this 
period the temperature of the reaction mixture rises to 240.degree. C. 
A vacuum of 50 mm Hg is then applied in the course of half an hour by means 
of a water pump and, at the same time, the reaction temperature is raised 
to 255.degree. C. Using a vacuum pump, the vacuum is increased, at a 
constant reaction temperature, to 0.07 mm Hg in the course of 15 minutes. 
15 minutes after this vacuum has been reached, the reaction is 
discontinued and the product is comminuted and subjected to a further 
condensation reaction (24 hours) in a thin layer at 210.degree. C. and 0.1 
mm Hg. This gives an amorphous polyester which has the following 
characteristics: 
Relative viscosity-- 1.74 dl/g 
Glass transition temperature (T.sub.g)-- 150.degree. C. 
Softening point-- 195.degree. C. 
EXAMPLE 2 
273 parts of 2-(diphenylamino)-4,6-bis-(p-carbethoxyanilino)-s-triazine 
(compound B) and 1 58 parts of 
2,2-bis-[4'-(.beta.-hydroxyethoxy)-phenyl]-propane (D 22) and 0.058 part 
of isopropyl titanate are filled into a 2 liter reactor fitted with a 
stirrer, a nitrogen inlet, a condenser and a device for measuring the 
temperature. 95% of the amount of methanol theoretically to be expected is 
distilled off in the course of 3 hours and 30 minutes, whilst stirring and 
passing nitrogen through the mixture, and during this period the 
temperature of the reaction mixture rises to 260.degree. C. A vacuum of 40 
mm Hg is applied in the course of half an hour by means of a water pump, 
whilst heating the reaction mixture to 270.degree. C. The vacuum is 
increased to 0.20 mm Hg, at a constant reaction temperature, in the course 
of 30 minutes using a vacuum pump. 21/2 hours after this vacuum has been 
reached, the reaction is discontinued and the product is comminuted and 
subjected to a further condensation reaction for 24 hours in a thin layer 
at 210.degree. C. and 0.1 mm Hg. This gives an amorphous polyester which 
has the following characteristics: 
Relative viscosity-- 1.80 dl/g 
Glass transition temperature (T.sub.g)-- 171.degree. C. 
Softening point (T.sub.s)-- 210.degree. C. 
EXAMPLES 3-5 
Various polyesters are prepared analogously to Example 1. Their 
characteristics and their composition are summarised in the table which 
follows: 
Table 1 
______________________________________ 
Exam- Molar T.sub.g 
T.sub.s 
ple No. 
Composition ratio .eta.rel 
(.degree. C.) 
(.degree. C.) 
______________________________________ 
3 Compound A + D22 
1:0.5:0.5 
1.51 170 200 
+ compound C 
4 Compound A + D33 
1:1 1.45 151 200 
5 Compound E + D22 
1:1 1.39 131 190 
______________________________________ 
Compound E=N,N'-bis-(4-carbobutoxybenzoyl)-m-phenylenediamine 
D 33= 2,2-bis-[4'-(.beta.-hydroxypropoxy)-phenyl]-propane 
Compound C=1,3-hydroxyethyl-4,5,6,7-tetrabromobenzimidazolone 
EXAMPLE 6 
(a) Test samples are prepared from a moulding composition prepared 
analogously to Example 1 and various properties, which are summarised in 
the table which follows, are measured on these samples. 
(b) For comparison with the above, a polybutylene terephthalate copolyester 
with 40 mol % compound A is prepared, test samples are prepared therefrom 
and the same properties are measured. 
Table 2 
______________________________________ 
b 
Property a (comparison) 
______________________________________ 
Maximum bending stress (kp/cm.sup.2) 
1,140 1,090 
DIN 53,452 
Modulus of elasticity from the 
20,000 17,000 
bending test DIN 53,452 (kp/cm.sup.2) 
Impact strength (cmkp/cm.sup.2) 
no break no break 
DIN 53,453 
Warm storage (130.degree. C., 50 days) 
22 45 
Reduction in the notched impact 
strength, in % 
Start of decomposition 
(thermogravimetry) 
in N.sub.2 (.degree. C.) 
334 320 
in air (.degree. C.) 
333 308 
Absorption of water in % 
2.5 2.5 
(in H.sub.2 O, 50 days) 
Stress cracking (= 2.5%, t = 1 
minute) 
in methanol resistant not resistant 
in diesel oil resistant not resistant 
Combustibility ASTM D 635 
70 90 
Burning time (seconds) 
70 90 
______________________________________ 
EXAMPLES 7-19 
Various polyesters are prepared analogously to Example 1. Their 
characteristics and their composition are summarised in Table 3 which 
follows. 
Table 3 
__________________________________________________________________________ 
Batch T.sub.g 
T.sub.s 
No. Composition Molar ratio 
.eta..sub.rel 
(.degree. C.) 
(.degree. C.) 
__________________________________________________________________________ 
7 B + C.sub.1 0.5:0.5 1.47 180 200 
8 B + IPA + C.sub.1 
0.35:0.15:0.5 
1.51 158 180 
9 B + TPA + D22 + CHDM 
0.35:0.15:0.25:0.25 
1.39 167 185 
10 B + TPA + D22 + 
0.4:0.1:0.25:0.25 
1.43 156 185 
1,6-hexanediol 
11 B + TPA + D22 0.4:0.1:0.5 
1.53 160 190 
12 B + TPA + IPA + D22 
0.25:0.15:0.1:0.5 
2.12 155 180 
13 D + B + D22 0.35:0.15:0.5 
1.46 152 175 
14 B + F 0.5:0.5 1.39 183 225 
15 I + D22 0.5:0.5 1.30 114 215 
16 K + D22 0.5:0.5 1.31 153 200 
17 L + D22 0.5:0.5 1.53 174 210 
18 M +D22 0.5:0.5 1.39 131 190 
19 N + D22 0.5:0.5 1.72 170 220 
__________________________________________________________________________ 
##STR6## 
Compound: 
X 
I CH.sub.2CH.sub.2 
Compound: 
R 
##STR7## 
L 
##STR8## 
M 
##STR9## 
N 
##STR10## 
Compound C.sub.1 : 
##STR11## 
Compound D: 
##STR12## 
Compound F: 
##STR13## 
__________________________________________________________________________ 
IPA = isophthalic acid 
TPA = tetraphthalic acid 
CHDM = 1,4-cyclohexanedimethanol 
D22 = 2,2-bis-[4'-(.beta.-hydroxyethoxy)-phenyl]-propane