Thermoplastic blow moldable polyethylene terephthalate compositions

Semi-crystalline blow moldable polyester compositions, formed by melt blending a polyester, an ethylene copolymer containing epoxide groups, an ionomer obtained by neutralizing with Na+ or K+ and optionally a second polyester.

BACKGROUND OF THE INVENTION 
Polyesters that are semicrystalline, particularly poly(ethylene 
terephthalate), PET, are used extensively in many applications that 
require good solvent resistance and good properties at elevated 
temperatures. They are ordinarily processed by injection molding, but 
there are many components of automobiles and other systems wherein such 
parts are hollow and to manufacture these by injection molding is very 
difficult and expensive. Many such parts can conceivably be made by blow 
molding provided the polymer system has adequate melt strength and melt 
viscosity and yields smooth high quality surfaces in the blow molded 
parts. Unfortunately, polyesters commercially available for injection 
molding and extrusion have melt viscosities which are too low to make them 
suitable for extrusion blow molding. It would be desirable to have blow 
moldable polyester compositions which provide moldings having smooth 
surfaces made from commercial injection moldable and extrusion grades of 
polyesters. 
The addition of conventional di- and polyepoxides and, more recently, the 
addition of ethylene copolymers containing glycidyl groups have been 
suggested for increasing the melt strength and viscosity of polyesters, 
but are not suitable for blow molding large objects having smooth surfaces 
and having complex cross-sections such as automobile parts. 
Further improvements in melt strength and melt viscosity have been provided 
by compositions which in addition to the ethylene copolymers containing 
glycidyl groups use small amounts of catalytic cations which may be 
introduced in the form of a zinc ionomer. Unfortunately it has been found 
that these catalyzed compositions may form small lumps when the 
compositions are exposed to processing temperatures for an extended period 
of time. Such prolonged exposure is not unusual in commercial blow molding 
operations where a substantial proportion of the resin must be recycled as 
regrinds. The presence of these lumps results in molded objects having 
surface blemishes or surface irregularities. 
Thus a need still exists for polyester compositions, particularly for 
PET-based compositions, which have sufficient melt strength and viscosity 
to permit extrusion blow molding of large and complex objects which at the 
same time exhibit uniform, smooth surfaces. 
BACKGROUND ART 
U.S. Pat. No. 4,659,757, granted Apr. 21, 1987 to Okamoto et al., discloses 
poly(ethylene terephthalate) (PET) molding compositions yielding impact 
resistant articles prepared by melt blending PET with 3 to 60 parts of a 
second polyester selected from the group consisting of (1) copolymers of 
ethylene glycol, terephthalic acid and aliphatic dicarboxylic acids 
containing at least 12 carbon atoms (2) copolymers of ethylene glycol, 
terephthalic acid and a poly(alkylene oxide) glycol, and (3) polyarylates. 
In addition the compositions must also contain (i) a nucleating agent 
selected from the group of finely divided inorganic nucleating agents, a 
metal salt of an organic carboxylic acid and an ionomer, (ii) a polyolefin 
to which has been grafted an olefin having carboxyl or anhydride groups, 
(iii) an olefin copolymer containing units derived from glycidyl 
(meth)acrylate and optionlly units derived from vinyl acetate as a third 
monomer and (iv) an ester-based plasticizer. As claimed, the compositions 
must contain the second polyester and each of ingredients (i), (ii), (iii) 
and (iv). 
U.S. Pat. No. 4,912,167, granted Mar. 27, 1990 to Deyrup et al and U.S. 
Pat. No. 4,914,156, granted Apr. 3, 1990 to Howe, disclose compositions 
which are blow moldable PET or poly(butylene terephthalate), PBT, 
containing an epoxide group-containing copolymer and a source of catalytic 
metal cations which source could be a small amount of a zinc ionomer, for 
example. The patents disclose olefin copolymers and acrylate copolymers 
containing epoxide groups, but prefers the olefin copolymers. The examples 
of the reference demonstrate that sodium ionomers are ineffective in 
providing blow moldability when used at the same concentration at which 
zinc ionomers are effective. 
U.S. Pat. No. 4,783,980, granted Jan. 28, 1988 to Deyrup discloses 
toughened thermoplastic polyester compositions prepared by melt blending 
at high shear 3-40 weight percent of an ethylene copolymer containing 
epoxide groups and 10-40 weight percent of units derived from a C.sub.2 
-C.sub.8 alkyl (meth)acrylate. A variety of optional ingredients may be 
added including plasticizers, poly(alkylene oxide) segments and 
crystallization promoters. As crystallization promoters one can use salts 
of hydrocarbon acids containing 7 to 54 carbon atoms or salts of ionomeric 
polymers. Example 1 discloses a single poly(ethylene terephthalate) 
composition which contains 3.8 weight percent of a sodium ionomer of an 
ethylene/methacrylic acid copolymer added as a crystallization promoter. 
U.S. Pat. No. 4,034,013 granted July 5, 1977 to Lane discloses that the 
notched impact strength and melt strength of PET and PBT are improved by 
incorporating small particles of a core-shell polymer wherein the core is 
a rubbery acrylate copolymer and the shell is a more rigid acrylate or 
styrene copolymer containing epoxide groups. 
Japanese Patent Publication 59-184251, published Oct. 19, 1984 discloses 
that polyether ester block copolymers (100 parts) derived essentially from 
terephthalic acid, 1,4-butanediol and a poly(alkylene oxide) glycol when 
melt blended with 1-25 parts of an ionomer resin and 1-25 parts of an 
olefin copolymer containing epoxide groups form compositions having 
sufficiently high melt tension to permit extrusion blow molding. The 
compositions are further characterized as exhibiting good elastic recovery 
and softness. 
U.S. Pat. No. 4,246,378, granted Jan. 20, 1981 to Kometani et al discloses 
the addition of ethylene copolymers containing glycidyl groups for 
increasing the melt strength and viscosity of polyesters. 
SUMMARY OF THE INVENTION 
The present invention provides polyester compostions which are suitable for 
extrusion blow molding large objects having smooth surfaces. The 
compositions are based on injection molding and extrusion grades of PET. 
More specifically, the compositions of the present invention are 
semi-crystalline blow moldable compositions comprising melt blends 
consisting essentially of the following ingredients: 
a) 62-88 weight percent of at least one PET selected from the group 
consisting of branched PET having an inherent viscosity of at least about 
0.60 dl/g and a mixture of the branched PET and a linear PET having an 
inherent viscosity of at least about 0.65 dl/g, the mixture containing up 
to 90 weight percent of the linear PET, 
b) 10-30 weight percent of at least one ethylene copolymer, E/X/Y, wherein 
E is at least 50 weight percent of units derived from ethylene, X is 2-10 
weight percent of units derived from glycidyl (meth)acrylate and Y is 0-40 
weight percent of units derived from a C.sub.1 -C.sub.6 alkyl 
(meth)acrylate, and 
c) 2-8 weight percent of at least one ionomer obtained by neutralizing with 
Na.sup.+ or K.sup.+ at least about 40 percent of the carboxyl groups in 
an ethylene copolymer which contains about 9-20 weight percent of units 
derived from (meth)acrylic acid and 0-35 weight percent of units derived 
from C.sub.1 -C.sub.6 alkyl (meth)acrylate. 
Optionally, component d), a second polyester other than PET, may be added 
in the amount of 2-6 parts per 100 parts (pph) by weight of components a), 
b) and c), which second polyester assists in the processing of the 
compositions. The second polyester is selected from the group consisting 
of (1) polyesters of C.sub.3 -C.sub.10 .alpha., .omega.-diols and aromatic 
dicarboxylic acids, (2) polyarylates and (3) copolyetherester block 
copolymers.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention relates to semi-crystalline blow moldable polyester 
compositions which possess high melt strengths and melt viscosities as 
well as yielding high quality smooth surface appearance on the blow molded 
parts. 
More specifically, the compositions of the present invention are 
semi-crystalline blow moldable compositions comprising melt blends 
consisting essentially of the following ingredients: 
a) 62-88 weight percent of at least one PET selected from the group 
consisting of branched PET having an inherent viscosity of at least about 
0.60 dl/g and a mixture of the branched PET with a linear PET having an 
inherent viscosity of at least about 0.65 dl/g, the mixture containing up 
to 90 weight percent of the linear PET, 
b) 10-30 weight percent of at least one ethylene copolymer, E/X/Y, wherein 
E is at least 50 weight percent of units derived from ethylene, X is 2-10 
weight percent of units derived from glycidyl (meth)acrylate and Y is 0-40 
weight percent of units derived from a C.sub.1 -C.sub.6 alkyl 
(meth)acrylate, and 
(c) 2-8 weight percent of at least one ionomer obtained by neutralizing 
with Na.sup.+ or K.sup.+ at least about 40 percent of the carboxyl 
groups in an ethylene copolymer which contains about 9-20 weight percent 
of units derived from (meth)acrylic acid and 0-35 weight percent of units 
derived from C.sub.1 -C.sub.6 alkyl (meth)acrylate. 
The weight percentages given for each of components a), b) and c) are based 
on the total of these components only. 
In the above description, and throughout this application the description 
"(meth)acrylate" is meant to include both "acrylate" and "methacrylate." 
Optionally, component d), a second polyester other than PET, may be added 
in the amount of 2-6 pph by weight of components a), b) and c), which 
second polyester assists in the processing of the compositions. The second 
polyester is selected from the group consisting of (1) polyesters of 
C.sub.3-C.sub.10 .alpha., .omega.-diols and aromatic dicarboxylic acids, 
(2) polyarylates and (3) copolyetherester block copolymers. 
Preferred compositions of the present invention are semi-crystalline blow 
moldable compositions comprising melt blends consisting essentially of the 
following ingredients: 
a) 69-82 weight percent of at least one PET selected from the group 
consisting of branched PET having an inherent viscosity of at least about 
0.60 dl/g and a mixture of the branched PET with a linear PET having an 
inherent viscosity of at least about 0.65 dl/g, the mixture containing up 
to 80 weight percent of the linear PET, 
b) 15-25 weight percent of at least one ethylene copolymer, E/X/Y, wherein 
E is at least 57 weight percent of units derived from ethylene, X is 4-8 
weight percent of units derived from glycidyl (meth)acrylate and Y is 
10-35 weight percent of units derived from a C.sub.1 -C.sub.6 alkyl 
(meth)acrylate, and 
(c) 3-6 weight percent of at least one ionomer obtained by neutralizing 
with Na.sup.+ or K.sup.+ at least about 40 percent of the carboxyl 
groups in an ethylene copolymer which contains about 9-20 weight percent 
of units derived from (meth)acrylic acid and 0-35 weight percent of units 
derived from C.sub.1 -C.sub.6 alkyl (meth)acrylate. 
Optionally, component d), a second polyester other than PET, may be added 
in the amount of 3-5 parts per 100 parts by weight of components a), b) 
and c), which second polyester assists in the processing of certain 
compositions. The second polyester is selected from the group consisting 
of (1) polyesters of C.sub.3 -C.sub.10 .alpha.,.omega.-diols and aromatic 
dicarboxylic acids, (2) polyarylates and (3) copolyetherester block 
copolymers. 
Component a) is a polyester selected from the group consisting of branched 
poly(ethylene terephthalate) (PET) having an inherent viscosity of at 
least 0.60 dl/g and mixtures of the branched PET with up to 90 weight 
percent of linear PET having an inherent viscosity of at least about 0.65 
dl/g. 
Linear PET is a well established commercial product which is normally made 
by esterification of terephthalic acid with ethylene glycol followed by 
polycondensation. PET having an inherent viscosity of about 0.65 dl/g may 
be made by polycondensation in the melt. PET having inherent viscosities 
of about 1.0 dl/g are usually prepared by subsequent solid phase 
polycondensation of lower molecular weight PET first prepared by melt 
condensation. Recycled PET bottle resin represents a source of relatively 
inexpensive linear PET which with proper recycling of PET bottles will be 
available in very substantial amounts. The PET used for bottles normally 
contains a minor amount, about 2% by weight, of a second glycol such as 
diethylene glycol, the presence of which facilitates the manufacture of 
oriented PET bottles; and normally has an inherent viscosity of at least 
0.65 dl/g and preferably has an inherent viscosity of about 0.7-0.72 dl/g. 
The presence of the second glycol monomer does not adversely affect the 
use of recycled PET resin in the present invention. 
Branched PET can be made by substantially the same processes as are used 
for linear PET with the exception that a minor amount of a tri- or higher 
functionality polyol or polyacid monomer is added to the polymerization. 
Trifunctional acids are usually preferred and of these, trimellitic 
anhydride or tri-lower alkyl esters of trimellitic acid are especially 
preferred. From about 0.2-1.0 mole of trifunctional monomer per 100 moles 
of terephthalic acid can be used with 0.4 to 0.7 moles being preferred. 
Branched PET containing preferred amounts of branching agent; i.e., 0.4 to 
0.7 moles of branching agent per 100 moles of terephthalic acid, are 
useful for preparing compositions of this invention which can be used for 
forming very large articles by extrusion blow molding. When blends of 
branched and linear PET are used, the higher the inherent viscosity of the 
linear PET, the smaller may be the proportion by weight of branched PET in 
the blends. The concentration of branching agent in the branched PET is 
also important in that a lesser amount of branched PET containing a higher 
level of branching agent is required than is a branched PET containing 
lower levels of branching agent. Compositions prepared from mixtures 
containing 10-60 weight percent branched PET, preferably 20-50 weight 
percent, having the preferred concentration of branching agent with 
recycled PET bottle resin, which normally has an inherent viscosity of 
about 0.7 dl/g, are very economical and highly useful for extrusion blow 
molding. 
Branched PET has a higher melt viscosity and greater melt strength than 
does linear PET having the same inherent viscosity. Because of these 
properties, branched PET having relatively low inherent viscosity is 
useful either alone or in admixture with linear PET in preparing the 
compositions of this invention. The use of branched PET alone or in blends 
with linear PET having a relatively low inherent viscosity yields 
compositions which are versatile in terms of the size and complexity of 
the articles which can be blow molded from them. For economic reasons, 
blends of branched PET with recycled PET bottle resin are of particular 
interest. 
Component b) is an ethylene copolymer, E/X/Y, where E is at least 50 weight 
percent of units derived from ethylene, X is 2-10 weight percent of units 
derived from glycidyl (meth)acrylate and Y is about 0-40 weight percent of 
units derived from C.sub.1 -C.sub.6 alkyl (meth)acrylate. Thus, component 
b may be a dipolymer of ethylene and glycidyl (meth)acrylate. More 
preferred are terpolymers containing up to 40 weight percent of units 
derived from meth(acrylate) lower alkyl esters of which n-butyl acrylate 
is preferred. Most preferred are terpolymers of ethylene containing 10-35 
weight percent of n-butyl acrylate and 4-8 weight percent of glycidyl 
methacrylate. 
Component b) is used in amounts of 10-30 weight percent, and more 
preferably 15-25 weight percent based on the total weight of components 
a), b), and c). Since components b) and c) each contribute to the blow 
moldability of the instant compositions by increasing melt viscosity, melt 
strength and die swell, the preferred amount of component b) used within 
the aforementioned ranges is partly dependent on the level of component 
c). The epoxide content of component b) is another factor which affects 
the amount of component b) used. In general, the greater the epoxide 
content of component b), the less of component b) will be required. 
Finally, consideration must be given to the proportion of branched PET 
used as well as its concentration of branching agent. 
Component c) is an ionomer obtained by neutralizing with Na.sup.+ or 
K.sup.+, provided by a basic sodium or potassium compound, at least about 
40 percent of the carboxyl groups contained in an ethylene copolymer 
containing about 9-20 weight percent of units derived from (meth)acrylic 
acid. Optionally these ionomers may oontain up to about 35 weight percent 
of units derived from C.sub.1 -C.sub.6 alkyl (meth)acrylate. A preferred 
termonomer is n-butyl acrylate. Component c) is used in amounts of 2-8 
weight percent, preferably 3-6 weight percent based on the total weight of 
components a), b), and c). Since component c) contributes to the blow 
moldability of the compositions of this invention, the preferred amount of 
component c) used depends at least in part on the amount of component b) 
present in a given composition. In addition, component c) improves the 
stability of the molten composition during processing which in turn 
permits extrusion of smooth parisons. 
As noted above, each of components b) and c) contributes to the blow 
moldability of the compositions of this invention. In general, increasing 
the concentration of either of the components within the ranges specified 
will raise the melt viscosity of a given blow molding composition. While 
blow moldability is more than a function of melt viscosity, for guidance 
it should be noted that compositions having melt viscosities at about 
270.degree. C. of at least about 10,000 to 15,000 Pa sec at 1 sec.sup.-1 
are usually suitable for forming articles requiring a parison of up 
to.about 61 cm (2 feet) in length and compositions having melt viscosities 
at the above temperature of at least about 20,000 to 30,000 Pa sec at 1 
sec.sup.-1 are usually suitable for forming articles requiring a parison 
greater than 61 cm in length. The melt rheology of the compositions df the 
present invention makes them suitable for thermoforming applications. 
Reference to the Samples contained below will assist one in selecting 
amounts of components b) and c) which will yield a composition suitable 
for a given molding application. 
As stated above, the addition of a minor amount of a polyester other than 
branched and/or linear PET may assist in the processing of certain 
compositions based on PET. Compositions melting near 250.degree. C or 
above generally exhibit melt viscosities which diminish rapidly with 
increasing tempertures in the range used for blow molding. The ratio of 
the melt viscosity at 27.degree. C. to the melt viscosity at 280.degree. 
C. may approach 10 for some compositions. Because of this extreme 
sensitivity of the melt viscosity to temperature, minor fluctuations in 
temperature on the low side result in excessive torque within the extruder 
of the blow molding machine while conversely, temperatures on the high 
side cause the melt to be too fluid to form a stable parison. Such 
compositions can only be blow molded satisfactorily in equipment where 
excellent temperature control is possible. By adding a minor amount of a 
second polyester, such sensitive compositions are converted to materials 
which can be readily processed in any conventional extrusion blow molding 
machine. The addition of a second polyester is usually not required for 
compositions of the present invention containing substantial amounts of 
recycled bottle PET because such PET already contains a second monomer 
which lowers the melting point of the composition and improves 
processibility. 
In essence, any polyester based on a diol other than ethylene glycol and/or 
based on a diacid other than terephthalic acid can be used to improve the 
processing of compositions which exhibit the problems just discussed. 
Polyesters based on aromatic diacids are preferred because compositions 
modified with aliphatic polyesters may exhibit decreased hydrolytic 
stability. Three classes of polyesters have been found to be particularly 
useful for the modification of temperature sensitive compositions. They 
are as follows: 
1. Polyesters of C.sub.3 -C.sub.10 .alpha., .omega.-diols and an aromatic 
dicarboxylic acid; 
2. Polyarylates of dihydric phenols and an aromatic dicarboxylic acid, and 
3. Copolyetherester block copolymers derived from a low molecular weight 
diol, a polyether glycol and an aromatic dicarboxylic acid. 
The polyesters of class 1 are close relatives of PET and can be prepared 
substantially by the same condensation procedures used to make PET. 
.alpha., .omega.-diols are preferred. Preferred dicarboxylic acids are the 
three isomeric phthalic acids, but substituted phthalic acids and acids 
such as 1,5-,2,6-and 1,4-naphthalene dicarboxylic acid are also useful. 
The preferred polyester of class 1 is PBT. 
The polyarylates of class 2 are aromatic polyesters derived from one or 
more dihydric phenols and one or more aromatic dicarboxylic acids. The 
dihydric phenol is preferably a bisphenol as described in U.S. Pat. No. 
4,187,358 having the structure: 
##STR1## 
wherein --X--is selected from the group consisting of nothing; i.e., a 
covalent bond, --O--, --S--, --SO.sub.2 --, --SO--, --CO--, an aIkylene 
group containing 1 to 5 carbon atoms and an alkylidene group containing 2 
to 7 carbon atoms, and R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.1 ', 
R.sub.2 ', R.sub.3 ', and R.sub.4 ', may be the same or different, and 
each is selected from the group consisting of a hydrogen atom, a chlorine 
atom, a bromine atom and an alkyl group containing 1 to 5 carbon atoms, 
and/or a functional derivative thereof. 2,2'-Bis(4-hydroxyphenyl)propane 
is most preferred. 
Additionally, up to 40 mole percent of mononuclear dihydric phenols may be 
used in combination with the bisphenols. Representative are hydroquinone 
and resorcinol and substituted derivatives thereof containing one to four 
substituents selected from the group consisting of chlorine, bromine and 
lower alkyl. 
Preferably, a mixture of 90 to 0 mole percent of terephthalic acid and/or 
the functional derivatives thereof and 10 to 100 mole percent of 
isophthalic acid and/or its functional derivatives is used as the acid 
component to be reacted with the bisphenol to prepare the polyarylate. 
Preparative methods for polyarylates are described in detail in U.S. Pat. 
Nos. 3,884,990, 3,946,091, 4,052,481 and 4,485,230. 
Preferred polyarylates for use in the compositions of this invention are 
derived from isophthalic acid optionally containing up to 30 weight 
percent terephthalic acid and 2,2'-bis(4-hydroxyphenyl)propane. 
The copolyetherester block copolymers of class 3 consist essentially of 
15-95 weight percent of short chain ester units which are derived from a 
low molecular weight diol and an aromatic dicarboxylic acid and 5-85 
weight percent of long chain ester units which are derived from a 
poly(alkylene oxide) glycol having a number average molecular weight of 
400-6000 and an aromatic dicarboxylic acid. These polymers are readily 
prepared by substantially the same procedures useful for preparing PET, 
with the exception of adding a poly(alkylene oxide) glycol to the reaction 
mass. Polymers derived from terephthalic acid (optionally containing some 
isophthalic acid), butanediol and a poly(alkylene oxide) glycol selected 
from the group consisting of poly(tetramethylene oxide) glycol, 
poly(1,2-propylene oxide) glycol and ethylene oxide-capped 
poly(1,2-propylene oxide) glycol are readily available as commercial 
products. 
Of the three classes of polyesters, those of class 1 are preferred with 
poly(butylene terephthalate) being especially preferred when molded 
articles having high flexural modulus are desired. It should be noted that 
the polyesters of class 3 which are known to be elastomers reduce the 
rigidity of the compositions of this invention and yield articles having 
outstanding impact resistance. 
When the compositions are modified by the addition of a second polyester, 
the second polyester should be used in amounts of 2-6 parts by weight, 
preferably 3-5 parts by weight, based on 100 parts of the sum of 
components a), b) and c). Note that the sum of the percentages of a), b) 
and c) equals 100 weight percent and the amount of the second polyester, 
being an optional component, is in addition to the weight of the basic 
composition. 
The compositions of the present invention may contain minor amounts of a 
variety of additives which are frequently used in plastics. Such additives 
include antioxidants, UV stabilizers, dyes, pigments, flame retardants, 
fibrillatable fluoropolymers and fillers. The use of reinforcing fillers 
such as chopped glass fibers and acicular calcium metasilicate permits the 
preparation of moldings which exhibit exceptional rigidity. Reinforcing 
fillers may be used in amounts of up to about 40 parts by weight based on 
100 parts of the total of components a), b) and c) which three ingredients 
total 100%. In other words, up to about 40 parts by weight of filler can 
be used for 100 parts by weight of components a), b) and c). The presence 
of reinforcing fillers generally raises the melt viscosity of the 
compositions of this invention. If significant amounts of reinforcing 
fillers are used it may be necessary to either (1) decrease the amounts 
within the limits specified herein of components b and c each of which 
enhances melt viscosity; or (2) employ a PET or PET mixture [component a)] 
with a lower melt viscosity. For instance, with 20 parts of acicular 
calcium silicate, compositions based on branched PET having an inherent 
viscosity of 0.65 dl/g are so viscous that they may overheat in the 
extruder. This problem may be remedied by replacing part of the branched 
PET with linear PET having an inherent viscosity of about 0.65 to 0.7 
dl/g. Because of their potentially low cost, filled compositions based 
largely on recycled bottle PET are of particular interest for blow molded 
articles exhibiting exceptional rigidity. 
In the following samples the various samples were prepared by melt blending 
the indicated ingredients, by extrusion in a 28 or 57 mm twin screw 
extruder. 
For Table VI and VIII below the ingredients of the compositions, namely 
components a, b and c, were added to the rear of the extruder. For 
illustration, the feed rates for Sample 8-1 are as follows: 
Component a: 53.0 kgs/hr 
Component b: 12.3 kgs/hr 
Additives A and B: 726 gms/hr 
The ingredients were blended on a Werner and Pfleiderer bilobal twin screw 
extruder having a diameter of 57 mm and a length to diameter ratio of 37. 
The screw used was a general purpose screw with vacuum capability 
consisting of conveying elements to convey the feed material from the feed 
zone to a melting zone in which the material was compressed and melting 
begins. A section of "kneading blocks" followed by "reverse elements" next 
provides high shear and pressure to further the melting and mixing 
process. The reverse elements serve also to provide a melt seal following 
which the melt is decompressed in the section under vacuum. Following the 
vacuum zone, introduced via a side feeder at the rate of 6.54 kg/hour was 
a mixture obtained by dry blending components c) and components d) at a 
ratio of 9.6 to 4.8, respectively. Also introduced via the side feeder was 
Additive C at the rate of 18.2 kg/hr. After the side feeder, the screw 
recompresses the melt and passes it through kneading blocks and reverse 
elements which also serve as a vacuum seal for a second vacuum zone. Then 
the melt is recompressed and mixed as it passes through the end of the 
extruder and out the die. 
Representative extrusion conditions for the compositions shown in Table 
VIII are: 
______________________________________ 
Setting 
Setting Setting Setting 
Setting Setting 
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5-10 
Die 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
______________________________________ 
260 260 260 260 260 260 
______________________________________ 
Screw Extru. Melt 
Speed Rate Temp 
Sample (rpm) Kg/hr (.degree.C.) 
______________________________________ 
8-1 225 90.8 326 
______________________________________ 
The product was extruded at a rate of 90.8 kgs/hour through a six hole die. 
Temperature of the melt exiting the extruder die was measured as the melt 
temperature. Melt strands exiting the extruder were quenched in water and 
cut into pellets. The pelletized product was dried at 
100.degree.-105.degree. C. in a circulating air drier equipped with 
dehumidifier. 
Representative extrusion conditions for the compositions shown in Table VI 
are: 
______________________________________ 
Setting 
Setting Setting Setting 
Setting Setting 
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5-10 
Die 
Temp Temp Temp Temp Temp Temp 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
______________________________________ 
270 270 270 270 270 270 
______________________________________ 
Screw Extru. Melt 
Speed Rate Temp 
Sample (rpm) Kg/hr (.degree.C.) 
______________________________________ 
6-1 175 68.1 326 
6-2 175 68.1 316 
6-3 175 68.1 323 
______________________________________ 
For the remaining Samples in Table VI, the amounts and proportions of the 
various components can be calculated from the information in Table VI. 
For Tables VII below the ingredients of the compositions were placed in a 
polyethylene bag and tumbled to mix. The resulting dry blend was melt 
blended on a Werner and Pfliederer twin-screw extruder having a diameter 
of 28mm and a length to diameter ratio of 27.5. The screw used is a 
general purpose screw with vacuum capability consisting of conveying 
elements to convey the feed material from the feed zone to a melting zone 
in which the material is compressed and melting begins. A section of 
"kneading blocks" followed by "reverse elements" next provides high shear 
and pressure to further the melting and mixing processes. The reverse 
elements serve also to provide a melt seal following which the melt is 
decompressed in the section under vacuum. Following the vacuum zone, the 
screw recompresses the melt and passes it through kneading blocks and 
reverse elements which also serve as a vacuum seal for this side of the 
vacuum zone. The melt is then further compressed and mixed as it passes 
through the end of the extruder and out the die. 
Representative extrusion conditions for the compositions shown in Table VII 
are: 
______________________________________ 
Setting 
Setting Setting Setting 
Setting Setting 
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Die 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
______________________________________ 
260 260 260 260 260 260 
______________________________________ 
Screw Extru. Melt 
Speed Rate Temp 
Sample (rpm) Kg/hr (.degree.C.) 
______________________________________ 
7-1 175 9.3 305 
7-2 175 8.2 313 
7-3 175 9.4 297 
7-4 175 7.8 312 
______________________________________ 
Temperatures of the melt exiting the extruder die were measured and 
reported above. The melt strand exiting the extruder was quenched in water 
and cut into pellets. The pelletized product was dried in a vacuum oven 
set a 120.degree. C. and purged with a slight nitrogen sweep overnight. 
For example, Sample 7-1 had a melt viscosity, measured using a Kayeness 
viscometer at 270.degree. C. of 30045 Pa sec at 1 sec-1, and 968 Pa sec at 
1000 sec-1. 
The dried resins for each extruded sample from Tables VI and VII were blow 
molded using a Rocheleau molding machine equipped with a single-screw 
extruder. The screw had a 3.81 cm diameter, a length to diameter ratio of 
20 and a compression ratio of 2 to 1. Samples marked with dashes denote 
that the particular sample was not blow molded. 
Representative blow molding temperature profiles used to produce the blow 
molded parts that appear on Table VI are: 
______________________________________ 
Setting Setting Setting 
Feed Transition Metering Setting 
Zone Zone Zone Die Zone 
(.degree.C.) 
(.degree.C.) (.degree.C.) 
(.degree.C.) 
______________________________________ 
270 270 265 260 
______________________________________ 
Screw 
Speed Mold 
Sample (rpm) Geometry 
______________________________________ 
6-1 54 Bottle 
6-2 73 Bottle 
6-3 110 Bottle 
______________________________________ 
Representative blow molding conditions and temperature profiles used to 
produce the blow molded parts that appear in Table VII are: 
______________________________________ 
Setting Setting Setting 
Feed Transition Metering Setting 
Zone Zone Zone Die Zone 
(.degree.C.) 
(.degree.C.) (.degree.C.) 
(.degree.C.) 
______________________________________ 
260 260 260 250 
______________________________________ 
Screw 
Speed Mold 
Sample (rpm) Geometry 
______________________________________ 
7-1 77 Bottle 
7-2 40 Bottle 
7-3 105 Bottle 
7-4 47 Bottle 
______________________________________ 
The resins for each Sample in the Tables above were extruded at the 
designated screw speed through the die to produce a parison. Upon closing 
the molded, the part is blown with air at about 400 MPa. The blown part is 
cooled in the mold under pressure and ejected. The mold geometry of the 
bottles are 22.5 cm high and 7.5 cm diameter; and the spoiler has 
dimensions of 136 cm long, 9 cm wide and 1.5 cm thick. 
Blow molded automobile spoilers, were also produced from the compositions 
of Table VIII. The procedure and conditions used for blow molding the 
spoiler are as follows: 
The dried resin product was blow molded using a Sterling blow molding 
machine equipped with a 819 cm diameter barrier type screw with a length 
to diameter ratio of 24:1 and an accumulator of the first-in-first-out 
design with a capacity of 6.8 kg. The extruder barrel of the blow molding 
machine was heated and the temperature reulated at 260.degree. C., 
260.degree. C. 255.degree. C. and 255.degree. C. for each of the four 
temperature zones, respectively. The three zones of the accumulator were 
set at 263.degree. C. The extruder screw was operated at a rate of 30 RPM. 
The automobile spoler mold was heated to 90.degree. C. 
A number of physical properties were measured for each composition. The 
notch Izod impact strength was determined according to ASTM D-256 measured 
at 23.degree. C. Tensile properties (tensile yield strength and 
elongation) at room temperature were measured by ASTM Procedure D-638. The 
flexural modulus was measured according to ASTM Procedure D-790. Samples 
were also tested for melt viscosity. The measurement of melt viscosity is 
described below: 
Blow molding resins were first dried in a vacuum oven at 110.degree. C. 
overnight. Melt viscosity was measured using a Kayeness Rheometer under 
the following test conditions: 
Temperature: 270.degree. C. and/or 280.degree. C. 
Die Length to diameter ratio: 20 
Die Length: 15.24 mm 
Die diameter: 0.76m 
Piston diameter: 9.53 mm 
Piston rate: 1.52 to 152 mm/minute 
In Table I, the inherent viscosities of PET were measured at 25.degree. C. 
according to ASTM Procedure D-2857, "Standard Method for Dilute Solution 
Viscosity of Polymers". Viscosity was measured using a solution containing 
0.5 gm polymer per 100 ml of solution. The solvent used consisted of a 
mixture of 1 part trifluoroacetic acid and 3 parts methylene chloride by 
volume. 
In the following samples, all percentages of component a), b) and c), are 
given by weight. The amounts of materials other than components a), b) and 
c) are given in parts per 100 parts of the total weight of components a), 
b) and c). All values originally obtained in British units have been 
converted to S.I. units and rounded, where appropriate, and finally blanks 
in the Tables denote either absence of a particular component or that a 
particular test was not run. 
TABLE I 
______________________________________ 
Identification of 
Component a) 
Code Description 
______________________________________ 
A Polyethylene terephthalate (PET) 
containing 0.5 mole percent trimethyl 
trimellitate branching agent with an 
inherent viscosity (IV) of 0.65 dl/g. 
B Recycled bottle resin, linear PET 
containing about 2 weight percent of 
comonomer, with an IV of 0.7 dl/g. 
C PET homopolymer with an IV of 1.0 
dl/g. 
______________________________________ 
Table II 
Identification of 
Component b) 
Description 
Terpolymer of ethylene/27% butyl acrylate/5% glycidyl methacrylate 
Table III 
Identification of 
Component c) 
Description 
Sodium ionomer derived from ethylene/15% methacrylic acid copolymer (MAA) 
in which 59% of the acid groups have been converted to the corresponding 
sodium salt. 
Table IV 
Identification of Component d) 
Description 
A copolymer prepared by ester interchange followed by polycondensation of 
4.52 moles of dimethyl terephthalate, 1.32 moles of dimethyl isophthalate, 
1.0 mole of polytetramethyleneether glycol (having a number average 
molecular weight of 980) and excess 1,4-butanediol in the presence of 
tetrabutyl titanate catalyst. 
TABLE V 
______________________________________ 
Identification of Additives 
Code Description 
______________________________________ 
A Tetrakis [methylene (3,5-di-ter-butyl 
4-hydroxyhydrocinnamate)] methane 
B Oxidized polyethylene used as a mold 
release agent. 
C Acicular naturally occuring calcium 
meta silicate, surface modified. 
______________________________________ 
Samples 6-1 to 6-3 in Table VI, demonstrate the significance of components 
c) and d) in compositions of the present invention. 
Sample 6-1, which is a control Sample contains no component c), the 
ionomer. Bottles could only be obtained at the very beginning of blow 
molding (when the screw was only partially filled) on this sample due to 
the poor processibility, as shown by the fact that the screw speed dropped 
to zero. 
Sample 6-2 which contains component c) shows a higher melt viscosity at 
both 1 sec-1 and 1000 sec-1 than Sample 6-1 but was significantly more 
processible than Sample 6-1 as shown by the screw speed. Parisons were 
extruded continuously and blown without difficulty for Sample 6-2. 
Sample 6-3 which contains a second polyester, component d, in addition to 
the ingredients used in Sample 6-2, shows good processibility as evidenced 
by the high screw speed despite its increased melt viscosity at shear 
rates of 1 sec-1 and 1000 sec-1 as compared to Sample 6-2. The bottles 
obtained for Sample 6-3 were smooth inside and outside. 
TABLE VI 
__________________________________________________________________________ 
Comparison of PET Blow Molding Resins 
__________________________________________________________________________ 
ID % % % pph 
Comp Comp Comp 
Comp Comp 
Additive 
Sample 
a a b c d A (pph) 
__________________________________________________________________________ 
*6-1 
A 80.39 19.62 
-- -- 0.326 
6-2 A 76.24 18.60 
5.15 -- 0.206 
6-3 A 76.24 18.60 
5.0 3.0 0.200 
__________________________________________________________________________ 
Viscosity 
Viscosity 
Pa sec @1 
Pa sec @1000 
Melt sec-1 sec-1 
Sample 
Temp (.degree.C.) 
RPM Kg/hr 
270.degree. C. 
280.degree. C. 
270.degree. C. 
280.degree. C. 
__________________________________________________________________________ 
*6-1 
324 175 68.1 43917 
12599 
1303 
632 
6-2 316 175 68.1 56909 
19536 
1409 
900 
6-3 323 175 68.1 65000 
32535 
1600 
900 
__________________________________________________________________________ 
Blow 
Molding 
Sample 
(RPM) 
Bottle Quality 
__________________________________________________________________________ 
*6-1 45.fwdarw.0 
Bottles ruptured in spots; uneven blow in the bottle 
6-2 65 Strong melt; bottle smooth outside, small specks inside 
6-3 130 Strong melt; bottle smooth outside and inside 
__________________________________________________________________________ 
*Control Sample 
Sample 7-1 through 7-4 in Table VII show PET compositions of the present 
invention containing linear PET and branched PET. 
In comparing Samples 7-1 and 7-3, Sample 7-1 gives bottles with smoother 
surface than Sample 7-3 which contained no component d and higher levels 
of ionomer component c). 
Compare control samples 7-2 and 7-4, which contain no branched PET to 
Samples 7-1 and 7-3 which contain branched PET. It can be seen that the 
control samples show lower processibility in the blow molding screw speed. 
TABLE VII 
__________________________________________________________________________ 
PET Formulation containing a Branched and Linear PET 
__________________________________________________________________________ 
ID % % % pph 
Comp Comp Comp 
Comp Comp 
Additive 
Sample 
a a b c d A (pph) 
__________________________________________________________________________ 
7-1 A 76.24 18.6 
5.17 3.1 0.21 
*7-2 
C 76.24 18.6 
5.17 3.1 0.21 
7-3 A 73.95 18.0 
8.02 -- 0.20 
*7-4 
C 73.95 18.0 
8.02 -- 0.20 
__________________________________________________________________________ 
Viscosity 
Viscosity 
Melt Pa sec @1 
Pa sec @1000 
Viscosity 
Sample 
Temp (.degree.C.) 
RPM Kg/hr 
sec-1 sec-1 Temp (.degree.C.) 
__________________________________________________________________________ 
7-1 305 175 9.2 30045 968 270 
*7-2 
313 175 8.2 26546 1149 270 
7-3 297 175 9.4 35368 1075 270 
*7-4 
312 175 7.8 41821 1387 270 
__________________________________________________________________________ 
Flex 
Blow 
Mod Molding 
Sample 
(MPa) 
(RPM) 
Bottle Quality 
__________________________________________________________________________ 
7-1 1482 
77 Strong melt; very smooth bottle 
*7-2 
1476 
40 Parison sagged in mold; bottle 
surface wavy; some lumps 
7-3 1462 
105 Slight specks on otherwise 
smooth surface 
*7-4 
1469 
47 Parison sagged in mold; bottle 
surface rough, many lumps 
__________________________________________________________________________ 
*Control Samples 
Sample 8-1 in Table VIII demonstrates the use of branched and linear PET in 
a composition of the present invention. The melt viscosities at both 1 
sec-1 and 1000 sec-1 are excellent and the blow molded automobile spoiler 
obtained showed very smooth surfaces and excellent melt strength. 
TABLE VIII 
__________________________________________________________________________ 
Filled Compositions Based on a Mixture of 
Branched and Recycled Bottle Linear PET 
__________________________________________________________________________ 
ID % % % pph 
Comp Comp Comp Comp Comp Additive 
Sample 
a a b c d A (pph) 
__________________________________________________________________________ 
8-1 A/B 15.2/60.8 
17.7 6.25 3.1 0.39 
__________________________________________________________________________ 
Melt Viscosity 
Viscosity 
Additive 
Additive 
Temp Pa sec @1 
Pa sec @1000 
Sample 
B (pph) 
C (pph) 
(.degree.C.) 
RPM Kg/hr 
sec-1 sec-1 
__________________________________________________________________________ 
8-1 0.65 26.0 326 225 90.8 
34000 1002 
__________________________________________________________________________ 
Sample 
Spoiler Quality 
__________________________________________________________________________ 
8-1 Strong melt; spoiler had reasonably smooth 
__________________________________________________________________________ 
surfaces