Preparation of linear polyester-polyepoxide reaction products via reactive concentrate

Branched polyester compositions having high melt viscosities, especially under conditions of low shear, are prepared in a two-step method. The first step is the reaction of a linear polyester, polycarbonate or polyester-polycarbonate containing free carboxylic acid groups with a polyfunctional epoxyalkyl compound such as triglycidyl isocyanurate to form a reactive concentrate. The second step is the reaction of said reactive concentrate with a polyester, such as poly(ethylene terephthalate) or poly(butylene terephthalate), containing a measurable proportion of carboxylic acid end groups. By this two-step method, it is possible to use less epoxy compound for a given melt viscosity level than is the case when the epoxy compound is directly blended with the polyester.

This invention relates to linear polyesters, and more particularly to the 
preparation therefrom of branched polyesters with advantageous melt 
viscosity properties. 
Linear polyesters, exemplified by poly(ethylene terephthalate) and 
poly(butylene terephthalate) (hereinafter "PET" and "PBT", respectively), 
are in wide industrial use for the preparation of articles by such forming 
methods as injection molding. Many of their properties, including chemical 
stability, solvent resistance and low permeability to gas, make them 
attractive candidates for such forming operations as blow molding, profile 
extrusion and thermo-forming. One problem in such operations is the 
relatively low melt viscosities of the polyesters, as a result of which 
the formed articles do not adequately retain their shape immediately after 
forming and before they have cooled. 
One method of increasing the melt viscosity of a linear polyester, 
described in U.S. Pat. No. 4,590,259, is to substantially increase its 
molecular weight. However, this can generally be achieved only with the 
use of specialized equipment. 
In order to maximize processability for processes that require high melt 
strength, such as blow molding, profile extrusion and sheet extrusion, it 
would be advantageous for the polyester to have low melt viscosity at high 
shear rates and high melt viscosity at low shear rates. For example, in 
blow molding low viscosity at high shear rates is desired in order to 
easily extrude the material, but high viscosity and high melt elasticity 
at low shear rates are necessary to maintain parison dimensions constant. 
Increasing molecular weight improves processing when high melt strength 
and viscosity are required at low shear rates, but has little or no effect 
on shear sensitivity. Thus, high molecular weight is ineffective to lower 
viscosity under conditions of high shear. 
In recent years, polyester materials which have melt viscosities and melt 
strengths capable of the desired variation have been developed. For 
example, Japanese Kokai 81/116749 describes the reaction of poly(ether 
ester) elastomers with triglycidyl isocyanurate (hereinafter "TGIC") to 
produce a material having desirable blow molding properties. Similar 
treatment of PBT is described in Japanese Kokai 75/96648. 
It is believed that upon treatment with a polyepoxide such as triglycidyl 
isocyanurate, a branched polyester is formed by reaction of the carboxylic 
acid end groups of the polyester with each of the epoxy groups. By reason 
of this branching, the polyester displays low viscosity at high shear 
rates, as during extrusion, and high viscosity and melt elasticity at low 
shear rates, as during hanging of a blow-molded parison, which insures 
dimensional stability. These are precisely the properties desired for such 
operations. 
A further advantage of this reaction is that it does not require specially 
designed facilities for polyester production. Ordinary equipment may be 
employed for the preparation of conventional polyesters such as PET, PBT 
and elastomeric polyesters. The conventional polyester is then blended 
with the polyepoxide and extruded under ordinary conditions, whereupon 
further reaction and branching take place. 
Upon further study of the reaction of polyesters with triglycidyl 
isocyanurate and similar polyepoxy compounds, it has been found that as 
the level of polyepoxide increases, melt viscosity increases to a very 
high level. From the standpoint of processability in normally employed 
equipment, the melt viscosity at the peak level may be considered 
infinite. At that level, therefore, the product is unworkable for purposes 
such as blow molding. An example of such a level is about 1-2% by weight 
for triglycidyl isocyanurate and a polyester having a carboxylic acid end 
group concentration in the range of 40-50 microequivalents per gram. 
Both above and below the peak level melt viscosity decreases, rapidly at 
first and then more slowly. Optimum conditions for the purposes of this 
invention are attained at a point some distance down the steepest part of 
the curve, but where the absolute value of its slope is still quite high. 
It is very difficult to attain that point reliably and uniformly by simply 
blending the polyester with the polyepoxy compound, as by melt blending 
using such operations as extrusion. Incomplete blending may result in 
regions of higher or lower melt viscosity, resulting in inhomogeneity and 
formation of lumps and/or regions of gel. Moreover, if the target level is 
missed by a relatively small value the melt viscosity may be much higher 
or lower than that desired and expected. One outcome may be flaw sites in 
the finally formed article. 
Another disadvantage of simple blending is the requirement of repeated and 
prolonged handling of polyepoxides, some of which are irritants and/or 
health hazards. For example, triglycidyl isocyanurate has mutagenic 
properties. Contact with the body and inhalation should therefore be 
avoided as much as possible. 
U.S. Pat. No. 4,141,882 deals by implication with the problem of 
near-infinite melt viscosity in compositions comprising PET and 
polyepoxides such as triglycidyl isocyanurate. The solution described 
therein is the employment of a relatively low molecular weight 
epoxide-reactive compound, typically a carboxylic acid such as benzoic 
acid. The polyepoxide and epoxide-reactive compound may be simultaneously 
blended with the polyester, but are preferably preblended to form a 
"modifier" which is in turn blended with the polyester. 
For various reasons, this solution frequently proves unsatisfactory. In the 
first place, the reaction of a low molecular weight epoxide-reactive 
compound with a polyepoxide proceeds statistically rather than 
selectively, so that some proportion of the polyepoxide molecules will 
have all their epoxy groups consumed while others will remain totally 
unreacted; this causes non-uniformity and consequent unpredictability in 
the morphology of the final product. In the second place, polyepoxide 
which has reacted with the epoxide-reactive compound has thus been at 
least partially inactivated, meaning that even in the best morphological 
situation more polyepoxide is required than if no such epoxide-reactive 
compound were employed. In the third place, a substantial proportion of 
the polyepoxide will be converted by reaction into an epoxide compound of 
lower functionality which operates only to endcap the polyester or extend 
the chains thereof. Thus, the best result is an increase in molecular 
weight alone, which is of limited value for reasons previously stated. 
Other problems are also encountered when low molecular weight 
epoxide-reactive compounds are employed. For example, the problems in 
handling the polyepoxide and blending it in useful proportion with the 
polyester are not addressed in any useful sense by partial reaction with 
another low molecular weight compound. Also, the use of such 
epoxide-reactive compounds as benzoic acid in proportions at the high end 
of the disclosed range may cause color formation in the polyester, which 
is undesirable in certain applications. 
The present invention provides an improved method for the preparation of 
linear polyester-polyepoxide compositions which may be converted to 
branched polyesters with favorable melt viscosity properties. Said method 
facilitates production of homogeneous materials free from potential flaw 
sites, and minimizes body contact with irritants and potentially harmful 
chemicals. It also minimizes usage of polyepoxide and the proportion 
thereof which will provide the desired melt viscosity properties. Finally, 
it includes novel compositions which are capable of conversion to 
essentially colorless branched polyesters having the desired properties. 
In one of its aspects, the present invention is a method for preparing a 
branched polymer which comprises the steps of: 
(I) forming a reactive concentrate by effecting reaction between (A) at 
least one poly(O- or N-epoxyalkyl-substituted) cyclic amide, iide or 
imidate with (B) at least one linear polymer having substantial 
proportions of at least one of ester and carbonate structural units and a 
measurable proportion of free carboxylic acid groups, and 
(II) melt blending said concentrate with (C) at least one linear polyester 
having a substantial proportion of free carboxylic acid groups; 
the proportion of reagent A employed in step I being at least about 3 parts 
by weight per 100 parts of reagent B, and about 0.1-3.0 parts per 100 
parts of the total of reagents B and C. 
Reagent A used in the method of this invention is at least one poly(O- or 
N-epoxyalkyl-substituted) cyclic amide, imide or imidate, usually 
containing one non-epoxy cyclic moiety although compounds with linked or 
fused moieties are also contemplated. It is most often a compound in which 
the epoxyalkyl group is bonded directly to the oxygen or nitrogen atom; 
however, compounds containing intervening structure, such as 
2-carboglycidyloxyethyl compounds, may also be used. The presence of more 
than one epoxy group per molecule is essential. At least three of such 
groups are highly preferred, with three and only three being especially 
preferred, by reason of the ease of preparation therefrom of branched 
polyesters with a minimum of crosslinking and resulting gel formation. 
Illustrative cyclic nuclei which may be present in reagent A are the 
triazine, barbiturate, hydantoin, uracil, pyromellitic diimide, 
piperazinedione and parabanate ring systems. As previously noted, the 
epoxy-containing functionalities may be present as substituents on oxygen 
or nitrogen atoms therein, with nitrogen atoms frequently being preferred. 
The most suitable compounds are triazine derivatives including triglycidyl 
cyanurate and TGIC. TGIC is particularly preferred by reason of its 
availability and particular suitability for the formation of branched 
polyesters. It has the formula 
##STR1## 
In step I of the method of this invention, a reactive concentrate is formed 
by the reaction of reagent A with (B) at least one linear polymer having 
substantial proportions (generally at least 40 and preferably 75-100 mole 
percent) of at least one of ester and carbonate structural units and also 
having free carboxylic acid groups as described hereinafter. It is 
apparent that this reagent may be a polyester, a polycarbonate, a 
polyester-polycarbonate or a copolyester or copolycarbonate with other 
structural units, provided the carboxylic acid end groups are present as 
described hereinafter. Linear polyesters are preferred. They may be 
crystalline or amorphous and are preferably crystalline. 
The ester structural units in reagent B typically have the formula 
##STR2## 
wherein each R.sup.1 is independently a divalent aliphatic, alicyclic or 
aromatic radical containing about 2-10 carbon atoms and each R.sup.2 is 
independently a divalent aliphatic, alicyclic or aromatic radical 
containing about 2-10 and usually about 6-10 carbon atoms. Polyesters 
containing such units may be prepared by the known reaction of dihydroxy 
compounds with dicarboxylic acids or functional derivatives thereof such 
as anhydrides, acid chlorides or lower alkyl (especially methyl) esters, 
preferably the esters. 
The R.sup.1 radicals may be one or more aliphatic or alicyclic hydrocarbon 
radicals containing about 2-10 carbon atoms, alicyclic radicals being 
known to those skilled in the art to be equivalent to aliphatic radicals 
for the purposes of the invention. They are most often derived from 
aliphatic or alicyclic dihydroxy compounds such as ethylene glycol, 
1,4-butanediol, propylene glycol, 1,3-propanediol, 1,6-hexanediol, 
1,10-decanediol, 1,4-cyclohexanedimethanol and 2-butene-1,4-diol. Aromatic 
dihydroxy compounds, especially bisphenols such as bisphenol A, may also 
be employed. The R.sup.1 radicals may also contain substituents which do 
not substantially alter the reactivity of the dihydroxy compound (e.g., 
alkoxy, halo, nitrile) or hetero atoms (e.g., oxygen or sulfur). The 
aliphatic and alicyclic R.sup.1 radicals are usually saturated. 
The R.sup.2 radicals may be derived from such acids as succinic, adipic, 
maleic, isophthalic and terephthalic acids or similar substituted and 
hetero atom-containing acids. 
Also contemplated are polymers in which at least a portion of the R.sup.1 
and/or R.sup.2 values are soft segment radicals such as poly(oxyethylene) 
or poly(oxybutylene). Such polymers may be prepared by incorporating 
compounds such as polyethylene glycol, caprolactone or dicarboxylic acids 
containing polyoxyalkylene segments in the polymerization reaction, and 
are typically elastomeric. Illustrative polyesters of this type are 
available from DuPont and General Electric under the trade names HYTREL 
and LOMOD, respectively. 
Preferably, R.sup.1 and R.sup.2 are hydrocarbon radicals, typically 
containing about 2-10 and preferably 2-6 carbon atoms. Most often, R.sup.1 
is aliphatic and R.sup.2 is aromatic. The polymer is most desirably a 
poly(alkylene terephthalate), particularly PET or PBT and especially the 
latter. It usually has a number average molecular weight of at least about 
4000, preferably in the range of about 10,000-70,000, as determined by gel 
permeation chromatography or by intrinsic viscosity (IV) at 30.degree. C. 
in a mixture of 60% (by weight) phenol and 40% 1,1,2,2-tetrachloroethane. 
Polycarbonates are also useful as reagent B. They typically contain 
structural units of the formula 
##STR3## 
wherein A.sup.1 is an aromatic radical. Suitable A.sup.1 values include 
m-phenylene, p-phenylene, 4,4'-biphenylene, 2,2-bis(4-phenylene)propane, 
2,2-bis(3,5-dimethyl-4-phenylene)propane and similar radicals such as 
those which correspond to the dihydroxyaromatic compounds disclosed by 
name or formula (generic or specific) in U.S. Pat. No. 4,217,438. Also 
included are radicals containing non-hydrocarbon moieties. These may be 
substituents such as chloro, nitro, alkoxy and the like, and also linking 
radicals such as thio, sulfoxy, sulfone, ester, amide, ether and carbonyl. 
Most often, however, all A.sup.1 radicals are hydrocarbon radicals. 
The A.sup.1 radicals preferably have the formula 
EQU --A.sup.2 --Y--A.sup.3 -- (III) 
wherein each of A.sup.2 and A.sup.3 is a divalent monocyclic aromatic 
radical and Y is a bridging radical in which one or two atoms separate 
A.sup.2 from A.sup.3 The free valence bonds in formula III are usually in 
the meta or para positions of A.sup.2 and A.sup.3 in relation to Y. Such 
A.sup.1 values may be considered as being derived from bisphenols of the 
formula HO--A.sup.2 --Y--A.sup.30 H. Frequent reference to bisphenols will 
be made hereinafter, but it should be understood that A.sup.1 values 
derived from suitable compounds other than bisphenols may be employed as 
appropriate. 
In formula III, the A.sup.2 and A.sup.3 values may be unsubstituted 
phenylene or substituted derivatives thereof, illustrative substituents 
(one or more) being alkyl, halo (especially chloro and/or bromo), nitro, 
alkoxy and the like. Unsubstituted phenylene radicals are preferred. Both 
A.sup.2 and A.sup.3 are preferably p-phenylene, although both may be o-or 
m-phenylene or one o- or m-phenylene and the other p-phenylene. 
The bridging radical, Y, is one in which one or two atoms, preferably one, 
separate A.sup.2 from A.sup.3. It is most often a hydrocarbon radical and 
particularly a saturated radical such as methylene, cyclohexylmethylene, 
2-[2.2.1]bicycloheptylmethylene, ethylene, 2,2-propylene, 
1,1-(2,2-dimethylpropylene), 1,1-cyclohexylene, 1,1-cyclopentadecylene, 
1,1-cyclododecylene or 2,2-adamantylene, especially a gem-alkylene 
radical. Also included, however, are unsaturated radicals and radicals 
which are entirely or partially composed of atoms other than carbon and 
hydrogen. Examples of such radicals are 2,2-dichloroethylidene, carbonyl, 
thio and sulfone. For reasons of availability and particular suitability 
for the purposes of this invention, the preferred radical of formula II is 
the 2,2-bis(4-phenylene)propane radical, which is derived from bisphenol A 
and in which Y is isopropylidene and A.sup.2 and A.sup.3 are each 
p-phenylene. 
Polyester-polycarbonates may also be used as component B. They are 
typically obtained by the reaction of at least one dihydroxyaromatic 
compound with a mixture of phosgene and at least one dicarboxylic acid 
chloride, especially isophthaloyl chloride, terephthaloyl chloride or 
both. Such polyester-polycarbonates contain structural units of formula II 
combined with units of formula I. 
For the purposes of this invention, it is essential that component B have a 
measurable proportion of free carboxylic acid groups, as determined by 
titration. In the case of polyesters and polyester-polycarbonates, these 
will usually be end groups, and their concentration is conventionally 
measured as microequivalents per gram. 
In the case of polycarbonates, carboxylic acid groups are frequently 
present as substituents on structural units derived from carboxylated 
bisphenols, as disclosed, for example, in U.S. Pat. No. 4,562,242, the 
disclosure of which is incorporated by reference herein. It is also 
possible, however, to prepare carboxylic acid-terminated polycarbonates by 
conventional interfacial polycarbonate methods employing a hydroxybenzoic 
acid or ester thereof as a chain termination agent, followed if 
appropriate by hydrolysis of the terminal ester groups. This method and 
the compositions prepared thereby are disclosed and claimed in copending, 
commonly owned application Ser. No. 109,873 filed Oct. 19, 1987, now U.S. 
Pat. No. 4,853,458. 
For the most part, a carboxylic acid group concentration in the range of 
about 5-250 microequivalents per gram is suitable. Polyesters may degrade 
to some extent on extrusion, increasing the concentration of such end 
groups which is available for reaction. It is, however, often preferred to 
employ polyesters having a carboxylic acid end group concentration in the 
range of about 10-100, especially about 30-100 and preferably about 40-80 
microequivalents per gram. 
The proportion of reagent A in the reactive concentrate, especially when 
reagent A is TGIC and reagent B is PBT, is at least about 3 and preferably 
about 3-20 parts by weight per 100 parts of reagent B. 
The preparation of the reactive concentrate may be effected in solution or 
in the melt. Melt reactions, typically involving extrusion, are generally 
preferred since they may be conveniently conducted in readily available 
equipment. Typically, reagents A and B are dry blended and are then 
extruded at temperatures in the range of about 200.degree.-300.degree. C. 
The reactive concentrate produced in step I is believed to comprise 
principally endcapped polyester, with a typical molecule thereof having 
two epoxide-functionalized end groups. Minor proportions of chain-extended 
polyester may also be present, as a result of reaction of at least two 
moles of polyester with one mole of polyepoxy compound. The concentrate is 
not believed to be significantly branched, and is similar in appearance 
and in many physical properties to the resin used as reagent B. No obvious 
indicia of phase separation are observed therein. 
The relevant physical properties of the concentrate are dominated by the 
polyester chains and are influenced very little by the 
epoxide-functionalized end groups. Consequently, said concentrate is 
highly compatible with unreacted polyester, yielding improved dispersion 
of the concentrate in step II described hereinafter. 
The concentrate is dust-free, and skin contact with and inhalation of 
reagent A are easily avoided. It may be readily pelletized for easy 
handling. By the preparation of (for example) one batch of said 
concentrate, continued or repeated handling of reagent A in high 
concentration is made unnecessary. 
In view of the much higher concentration of reagent A employed in 
preparation of the concentrate than in preparation of the blends of the 
prior art, it is unexpected that said concentrates are so similar in 
properties to the polyesters used in their preparation. 
In step II, the reactive concentrate prepared in step I is melt blended 
with at least one linear polyester having a measurable proportion (as 
previously defined) of free carboxylic acid groups. The polyesters 
described hereinabove with respect to reagent B are also suitable for use 
as reagent C; in fact, it is generally preferred for reagents B and C to 
be the same polyester. However, another advantage of the invention is the 
ability to tailor the product by such expedients as employing PBT as 
reagent B and PET as reagent C. 
The melt blending conditions employed in step II are generally identical to 
those employed in step I when it is effected in the melt. The proportions 
of reactive concentrate and reagent C, especially when reagent A is TGIC 
and reagents B and C are both PBT, are such as to provide, in a formal 
sense, about 0.1-3.0 parts and preferably about 0.4-0.6 part of reagent A 
per 100 parts of reagents B and C combined. (Of course, reagent A as such 
is not present--at least not in these proportions--in step II since a 
significant proportion thereof has reacted with reagent B.) 
The method of this invention is frequently conveniently effected by dry 
blending the reactive concentrate with reagent C to form an intimate solid 
blend which is then melt processed as previously described. By reason of 
the uniformity and relatively low concentration of epoxide groups in the 
reactive concentrate, it is easy to "fine-tune" the concentration of such 
groups in the blend with reagent C, optimizing further reaction and 
attainment of the desired melt viscosity. 
Accordingly, another aspect of the invention is a composition comprising a 
blend of the previously described reactive concentrate and reagent C, 
reagent A being employed therein in the amount of about 0.1-3.0 parts by 
weight per 100 parts of the total of reagents B and C. 
Other materials which are chemically substantially inert may be blended 
into the compositions prepared by the method of this invention, at any 
appropriate stage of blending and especially during step II. Such 
materials include fillers, reinforcing materials, flame retardants, 
pigments, dyes, stabilizers, anti-static agents, mold release agents and 
impact modifying polymers, the latter being exemplified by core-shell 
polymers having a core comprising alkyl acrylate, diene and/or styrene 
units and a shell comprising alkyl methacrylate units. 
The viscosity properties of polyester-TGIC compositions are illustrated by 
a series of experiments in which the polyester employed was the PBT 
described hereinafter in Example 1. Table I lists melt viscosities and 
intrinsic viscosities (in the above-identified phenol-tetrachloroethane 
mixture) of the original PBT, extruded PBT and various PBT-TGIC mixtures 
prepared by dry blending and extrusion, also as described in Example 1. 
TABLE I 
______________________________________ 
Parts TGIC per Melt visc., 
IV, 
100 parts PBT poises .times. 10.sup.2 
dl./g. 
______________________________________ 
0 (untreated PBT) 
75 1.15 
0 (extruded PBT) 55* -- 
0.2 126 -- 
0.4 314 -- 
0.6 1579 -- 
1.0 ** 1.36 
3.0 146 1.18 
4.0 104 -- 
5.0 60 1.11 
6.0 70 -- 
7.0 39 1.07 
10.0 22 1.00 
20.0 20 -- 
______________________________________ 
*Average value. 
**Did not flow. 
From the table, it is apparent that a substantial increase in melt 
viscosity, accompanied by a modest increase in intrinsic viscosity, is 
exhibited upon increase of the TGIC proportion to a value on the order of 
1-2 parts per 100 parts of PBT. At 3.0 parts of TGIC and above, the melt 
viscosity drops rapidly, reaching essentially the value of PBT in the 
range of 5-7 parts and dropping even lower as the TGIC concentration is 
further increased. Thus, the preparation of concentrates in accordance 
with step I of this invention affords materials having properties which 
most resemble those of unreacted PBT, as opposed to blends containing TGIC 
in smaller proportions which have materially higher melt viscosities. 
The conditions of step II provide excellent dispersion of the reactive 
concentrate in reagent C, insuring a high and uniform degree of branching 
throughout the composition and minimizing undesirable gel formation. The 
compositions thus obtained generally exhibit much lower melt viscosities 
than those listed in Table I when subjected to high shear. Thus, they may 
be conveniently extruded for purposes such as blow molding and profile 
extrusion. Said compositions also generally have higher melt viscosities 
after extrusion than blends of neat TGIC with polyesters in the same 
proportions, and frequently exhibit other beneficial properties as 
compared with unmodified polyesters, particularly higher impact strength 
and improved ductility.

The method of this invention is illustrated by the following examples. 
EXAMPLE 1 
A PBT having a number average molecular weight (as determined by gel 
permeation chromatography) of about 50,000 and a carboxylic acid end group 
concentration of about 45 microequivalents per gram was dried for 4 hours 
at 120.degree. C. in a circulating air oven and was then dry blended with 
TGIC in various proportions and extruded on a twin screw extruder at 400 
rpm. and 266.degree. C. The extrudates, which were the desired reactive 
concentrates, were quenched in water, pelletized and redried. They were 
then dry blended with further PBT and extruded under similar conditions. 
The relevant proportions and melt viscosities are given in Table II. Melt 
viscosities were determined at 250.degree. C. on a Tinius-Olsen melt 
plastometer. 
TABLE II 
______________________________________ 
Parts TGIC 
per 100 parts PBT Blend melt visc., 
Concentrate Blend poises .times. 10.sup.2 
______________________________________ 
20 0.5 371 
6 0.4 281 
5 0.4 356 
4 0.4 368 
3 0.4 378 
______________________________________ 
EXAMPLE 2 
Following the procedure of Example 1, the further concentrates and blends 
listed in Table III were prepared from the same PBT. 
TABLE III 
______________________________________ 
Parts TGIC per 100 parts PBT 
Concentrate 
Blend 
______________________________________ 
3.0 0.4 
4.3 0.53 
5.0 0.6 
5.3 0.51 
6.3 0.5 
7.5 0.5 
11.1 0.5 
25.0 0.5 
______________________________________ 
EXAMPLE 3 
The procedure of Example 1 was repeated, replacing the PBT in step II with 
a commercially available PET (Grade 5202A available from Rohm & Haas 
Company). The results are given in Table IV. Melt viscosity measurements 
were made at 265.degree. C. 
TABLE IV 
______________________________________ 
Parts TGIC per 100 parts polyester 
Blend melt visc., 
Concentrate Blend poises .times. 10.sup.2 
______________________________________ 
0 0* 14.6 
0 0** 13.2 
10 0.5 39.8 
20 1.0 47.4 
______________________________________ 
*Untreated PET. 
**Extruded PET. 
EXAMPLES 4-6 
Following the procedure of Example 1, TGIC-containing concentrates were 
prepared using the following polymers as reagent B: 
Example 4 --"KODAPAK 7352", a commercially available PET having an 
intrinsic viscosity of 0.74 dl./g. 
Example 5 --"CLEARTUF 1006B", a commercially available PET having an 
intrinsic viscosity of 1.04 dl./g. 
Example 6 --"HYTREL 4056", an elastomeric polyester commercially available 
from DuPont. 
Said concentrates were then blended with the PBT of Example 1 and the 
blends were extruded under the conditions employed in that example. The 
melt viscosities of the products were compared with those of controls 
comprising polyester blends from which the TGIC was absent. The relevant 
parameters and test results are given in Table V. 
TABLE V 
______________________________________ 
Concentrate Blend 
Parts Parts 
TGIC per TGIC per Melt viscosity 
100 parts Extrusion 
100 parts poises .times. 10.sup.2 
Example 
polymer temp., .degree. C. 
polymer Product 
Control 
______________________________________ 
4 5.3 271 0.5 422 95 
5 5.3 266 0.5 -- -- 
6 11.1 210 0.5 392 70 
______________________________________