Process for preparing poly(ester-amides)

Disclosed is a process for preparing poly(ester-amides) by aminolysis of polyesters and glycol esters with diamines or aminoalcohols and then polycondensation. This process is thus useful in the production of poly(ester-amides) which find application in the production of fibers, films, sheets, molded objects, and other products.

DESCRIPTION 
1. Technical Field 
This invention relates to a process for preparing poly(ester-amides) by 
aminolysis of polyesters and glycol esters with diamines or aminoalcohols 
and then polycondensation. This process is thus useful in the production 
of poly(ester-amides) which find application in the production of fibers, 
films, sheets, molded objects, and other products. 
2. Background of the Invention 
Poly(ester-amides) prepared by conventional melt techniques of ester 
interchange of a glycol and diamine with a dialkyl ester of a dicarboxylic 
acid are generally low molecular weight and are highly colored. It is very 
surprising that high inherent viscosity, tough, clear, light yellow 
polymers can be prepared using an aminolysis process. Poly(ester-amides) 
can also be prepared using a dicarboxylic acid instead of the dialkyl 
ester of a dicarboxylic acid, but since the amine-acid reaction proceeds 
at elevated temperatures at a much higher rate than does glycol-ester 
interchange, a heterogeneous polymer composition is obtained. In many 
cases, particularly with aromatic acids, a low molecular weight product is 
obtained because of solidification caused by high-melting polyamide 
blocks. Poly(ester-amides) prepared using our new aminolysis process are 
high molecular weight, tough polymers. 
Tough films are obtained from the polymers of this invention by pressing or 
by extrusion. Molding plastics having good properties are obtained by 
injection molding at about 240.degree.-300.degree. C., depending on the 
melting point of the poly(ester-amide). In addition to plastics, the 
compositions of this invention may be fabricated to give other types of 
shaped objects, such as foamed plastics, fibers. films extruded shapes, 
and coatings. 
Of interest is Bull. Acad. Sci., USSR, pages 202-204 (1958) which describes 
the aminolysis of poly(ethylene sebacate) with 1,6-hexanediamine. No other 
polyesters or diamines are disclosed as reactants. 
DESCRIPTION OF THE INVENTION 
According to the present invention, there is provided a process for 
preparing linear condensation poly(ester-amides) which comprises reacting 
in a molten form a compound of the formula 
##STR1## 
wherein n is 1-200 and R is a divalent alicyclic radical having 4 to 20 
carbon atoms, a divalent aliphatic radical having 4 to 20 carbon atoms or 
a divalent aromatic radical having 6 to 16 carbon atoms with the carbonyl 
linkages separated by at least 3 carbon atoms, with (a) about 5-50 mol % 
of a diamine of the formula 
EQU NH.sub.2 --CH.sub.2 --R.sup.1 --CH.sub.2 --NH.sub.2 
wherein R is a divalent alicyclic radical having 4 to 20 carbon atoms, a 
divalent aliphatic radical having 0 to 20 carbon atoms or a divalent 
aromatic radical having 6 to 16 carbon atoms, or (b) about 5-80 mol % of 
an aliphatic or cycloaliphatic amino alcohol having 4-20 carbon atoms to 
form a high melt viscosity polymer having an I.V. of at least 0.4. Also, 
the present invention provides poly(ester-amides) having an I.V. of at 
least 0.4 and having repeating units of 
##STR2## 
wherein R is a divalent alicyclic radical having 4 to 20 carbon atoms a 
divalent aliphatic radical having 4 to 20 carbon atoms, or a divalent 
aromatic radical having 6 to 16 carbon atoms with the carbonyl linkages 
separated by at least 3 carbon atoms, and R.sup.1 is a divalent alicyclic 
radical having 4 to 20 carbon atoms, a divalent aliphatic radical having 0 
to 20 carbon atoms or a divalent aromatic radical having 6 to 16 carbon 
atoms. 
Examples of dicarboxylic acids that can be used to prepare the starting 
polyester or glycol ester include terephthalic, isophthalic, adipic, 
azelaic, suberic, pimelic, sebacic, the isomeric cyclohexanedicarboxylic 
acids, sulfonyldibenzoic diphenic, oxydibenzoic, methylenedibenzoic, 
monochloroterephthalic, dichloroterephthalic, and naphthalenedicarboxylic 
acids. Neopentyl glycol is used as the diol component. 
The aminolysis of the polyester may be carried out with 5-50 mol % of 
aliphatic or cycloaliphatic diamines having 2 to 20 carbon atoms. Examples 
include ethylenediamine, propylenediamine, and hexamethylenediamine. 
Branched chain aliphatic diamines such as 3-methylhexamethylenediamine, 
2-ethylhexamethylenediamine, 3-methylheptamethylenediamine, etc., also may 
be used. Amines containing an alicyclic nucleus can be advantageously 
used, as represented by 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 
1,4-cyclohexanebis(methylamine), etc. 
Aminolysis of the polyester can also be carried out with 5-80 mol % of 
aliphatic or cycloaliphatic aminoalcohols containing from 4 to 20 carbon 
atoms such as 4-aminomethylcyclohexanemethanol, 5-amino-1-pentanol, 
5-amino-2-ethyl-1-pentanol-1, 5-amino-2,2-dimethyl-1-pentanol, etc. 
Aminoalcohols containing only 2 and 3 carbon atoms apparently form cyclic 
componds during the preparation of the poly(ester-amides). 
The poly(ester-amides) of the invention are made by aminolysis of a 
polyester with a diamine or an aminoalcohol. In a typical laboratory 
preparation, the reactants are placed in a flask and evacuated and purged 
five times with nitrogen (to remove all traces of oxygen) before being 
heated at 120.degree. C. with stirring under nitrogen. The reactants are 
then heated to about 200.degree. C. (or at a temperature just below the 
boiling point of the diamine or aminoalcohol if its boiling point is lower 
than 200.degree. C.). The temperature of the bath is then increased to 
about 250.degree.-260.degree. C. and held for 15 minutes. At this stage, a 
clear, low melt viscosity product is obtained because of aminolysis of the 
polyester. A vacuum of about 0.5 millimeter is applied so that glycol can 
be distilled out, and stirring is continued until a high-melt viscosity 
polymer is obtained. The molecular weight of a crystalline prepolymer may 
be increased to a high value by heating particles of the polymer in an 
inert atmosphere or under reduced pressure at a temperature just below the 
softening point of the polymer. 
The compositions of this invention also may contain nucleating agents, 
organic fibers, pigments, glass fibers, asbestos fibers, antioxidants 
plasticizers, lubricants, and other additives. 
The poly(ester-amides) may be prepared in the melt by carrying out 
aminolysis of the polyester with either the diamine or amino alcohol. A 
typical experimental procedure for preparing poly(neopentylene 
terephthalate) and then a poly(ester-amide) is given below. 
97 g (0.5 mol) dimethyl terephthalate 
104 g (1.0 mol) 2,2-dimethyl-1,3-propanediol 
0.9 mL titanium tetraisopropoxide butanol solution 
The above ingredients are placed in a 500 mL flask and heated in a Wood's 
metal bath at 205.degree.-220.degree. C. with stirring under N.sub.2 for 
90 minutes. To remove the last traces of methanol, a partial vacuum (250 
mm Hg) is then applied for 30 minutes. The product is allowed to cool and 
28.6 g (0.2 mol) 4-aminomethylcyclohexanemethanol is added to the flask. 
The flask 90 minutes. The temperature of the bath is then is then heated 
at 200.degree. C. with stirring under N.sub.2 for increased to 275.degree. 
C. and held for 15 minutes. A vacuum of 0.5 mm of Hg is applied for 60 
minutes. A high melt viscosity, light amber, clear polymer with an I.V. of 
0.76 is obtained. NMR analysis indicates that the polymer contains 36 mol 
% of the aminoalcohol. 
Inherent viscosities (I.V.) are determined at 25.degree. C. in 60/40 
phenol/tetrachloroethane at a concentration of 0.50 g/100 mL. The melting 
points (Tm) and glass transition temperatures (Tg) are determined with a 
Perkin-Elmer DSC-2 differential scanning calorimeter. NMR spectra are 
determined on trifluoroaceticacid solutions of the poly(ester-amides) with 
a Varian A-60 spectrometer. Gel permeation chromatographic (gpc) data are 
obtained with a Waters, Model 200, gel permeation chromatography unit in 
m-cresol as a solvent at 100.degree. C. 
The polymers are dried in an oven at 80.degree. C. overnight and 
injection-molded to give 21/2.times.3/8.times.1/16-in. tensile bars and 
5.times.1/2.times.1/8 in. flexure bars for testing. ASTM procedures are 
used for measuring the tensile strength and elongation (ASTM D 1708) and 
flexural modulus (ASTM D 790). 
The following examples are submitted for a better understanding of the 
invention.

EXAMPLE 1 
This example illustrates the preparation of a poly(ester-amide) from 
poly(neopentylene terephthalate) by modification with 20 mol % 
1,6-hexanediamine. A mixture of 128.7 g (0.55 mol) of poly(neopentylene 
terephthalate) (I.V. 0.63) and 12.8 g (0.11 mol) of 1,6-hexanediamine is 
placed in a 500-ml flask equipped with a stirrer, a short distillation 
column and inlet for nitrogen. The flask is evacuated and purged five 
times with nitrogen before being lowered into a Wood's metal bath 
maintained at 120.degree. C. The mixture is heated under a nitrogen 
atmosphere with stirring to a temperature of 190.degree. C. A clear, light 
yellow, low melt viscosity product is obtained within 15 minutes. The 
temperature of the bath is then increased to 260.degree. C. for 15 
minutes. A vacuum of 0.5 mm of mercury is then applied over a period of 10 
minutes. After stirring is continued under 0.5 mm of mercury at 
260.degree. C. for 110 minutes, a high melt viscosity, clear, light amber 
polymer is obtained. The polymer has an inherent viscosity of 0.64 and a 
glass transition temperature of 84.degree. C. A nuclear magnetic resonance 
(NMR) spectrum shows that the polymer contains about 22 mol % 
1,6-hexanediamine. Gel permeation chromatographic (gpc) analysis shows 
that the polymer has a normal molecular weight distribution (Mw/Mn 2.1, 
Mz/Mn 4.4) where Mn is number average molecular weight. Mw is weight 
average molecular weight, and Mz is "Z" average molecular weight. 
Injection-molded bars have the following properties: tensile strength 7200 
psi, elongation 88%, flexural modulus 3.2.times.10.sup.5 psi. 
A broader molecular weight distribution (Mz/Mn 25, indicating branching) is 
obtained when the same poly(ester-amide) is prepared conventionally with 
terephthalic acid, neopentyl glycol, and 20 mol % 1,6-hexanediamine or 
when a poly(ester-amide) is prepared from poly(ethylene terephthalate) and 
20 mol % 1,6-hexanediamine (Mz/Mn 86). Lower ratios of Mz/Mn are 
indicative of linear polymers. 
EXAMPLE 2 
This example illustrates the preparation of a poly(ester-amide) from 
poly(neopentylene terephthalate) and 40 mol % 
4-aminomethylcyclohexanemethanol. A copoly(ester-amide) is prepared with 
0.1 mol of poly(neopentylene terephthalate) (I.V. 0.63) and 0.04 mol of 
4-aminomethylcyclolexanemethanol by the procedure of Example 1. A clear, 
light amber polymer is obtained. The polymer has an inherent viscosity of 
0.48 and a glass transition temperature of 109.degree. C. A film pressed 
from the polymer is clear and creasable. .sup.13 C NMR analysis shows that 
the polymer contains 40 mol % 4-aminomethylcyclohexanemethanol. Gpc 
analysis shows that the polymer has a normal molecular weight distribution 
(Mw/Mn 2.3. Mz/Mn 4.9). 
EXAMPLE 3 
A poly(ester-amide) is prepared with 0.1 mol of poly(neopentylene 
terephthalate) (I.V. 0.63) and 0.02 mol of 1.4-cyclohexanebismethylamine 
by the procedure of Example 1. The polymer has an inherent viscosity of 
0.42 and a glass transition temperature of 100.degree. C. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.