A molding composition of a terephthalate polyester such as PET, a plasticizing material and a crystal nucleating agent. The nucleating agent is a powdered metal hydroxide such as aluminum hydroxide, which raises the T.sub.cc of the composition and permits reduced cycling time and enables higher molecular weight polymer to be used in the molding process.

DESCRIPTION 
1. Field of the Invention 
This invention relates to the molding of crystallizable, linear, saturated 
polyester compositions and more particularly, to a composition wherein the 
temperature of crystallization of the polyester has been increased by the 
addition of an inorganic nucleating agent. 
2. Description of the Prior Art 
Thermoplastic, linear polyesters such as poly(ethylene terephthalate) and 
poly(butylene terephthalate) can be produced on a large scale at 
relatively low cost and have excellent physical properties in the 
crystalline state such as thermal stability due to their high melting 
points and low moisture absorption. In spite of these advantages 
poly(ethylene terephthalate) has found only limited use in the molding 
field due to the difficulty of converting them into crystallized articles 
with conventional molding equipment. Unmodified poly(ethylene 
terephthalate) crystallizes slowly from the melt making the process 
uneconomical and producing an article of non-uniform spherulite growth, 
low impact resistance, poor dimensional stability and rough surface. It 
also requires high molding temperatures which tend to degrade the 
polyester. Furthermore, the long mold cycle results in a long residence 
time of the polymer in the hot barrel of the processing equipment, 
severely degrading the polyester. 
Strength, dimensional stability and toughness of poly(ethylene 
terephthalate) can be improved by incorporating reinforcing materials such 
as glass fibers or mica. However, when such reinforcing materials are 
used, as is recommended in U.S. Pat. No. 3,368,995, molding temperatures 
of from 120.degree. C. to 200.degree. C. are required to obtain articles 
with good mold release and glossy surface appearance. Such high 
temperatures cannot be obtained with conventional molding equipment 
because molds are heated with water and only can obtain molding 
temperatures of up to 110.degree. C. Higher temperatures can be reached by 
means of oil-heated molding devices, but they are generally inconvenient, 
costly and hard to use. 
These difficulties are well known and described in the prior art, and 
numerous attempts were made to overcome them. Netherlands Application No. 
651174 recommends the addition of finely divided, inert, inorganic 
materials of particle size smaller than 2 microns to poly(ethylene 
terephthalate). Examples of the solid, inorganic substances that have been 
proposed are glass powder, carbon, talc, pyrophyllite, alkaline earth 
metal carbonates and metal oxides. These powders are introduced as seeding 
or nucleating agents to induce the formation of the first polyester 
crystals and thereby shorten the time of crystallization and the molding 
rate. Although these inert, inorganic additives produce some improvements 
in the density and dimensional stability of the shaped articles, the 
molding compositions so obtained still require molding temperatures above 
120.degree. C. and molding cycles of over 60 seconds. 
Several other additives have been proposed in combination with an inert, 
inorganic nucleating agent: U.S. Pat. No. 3,583,935 discloses the addition 
of a mold release agent consisting of an organic ester and an alkali metal 
salt or alkaline earth metal salt of an organic acid to the poly(ethylene 
terephthalate). British Pat. No. 1,315,699 recommends the admixture of a 
sodium, lithium or barium salt of a mono- or polycarboxylic acid to a 
saturated linear polyester. U.S. Pat. No. 3,583,935 proposes a composition 
containing up to 3% of epoxides of the formula 
##STR1## 
All these compositions tend to produce an improvement in the physical 
properties and surface appearance of the molded article, but they do not 
resolve the basic problems of molding poly(ethylene terephthalate)-based 
compositions as described hereinbefore, namely the need for high molding 
temperatures and long molding cycles. 
U.S. Pat. Nos. 3,435,093; 3,516,957 and 3,639,527 and Netherland 
application Nos. 79-01605 and 79-01609 disclose the use of ionic 
copolymers of .alpha.,.beta.-unsaturated olefins and with 
.alpha.,.beta.-unsaturated carboxylic acids in which all or a portion of 
the pendant carboxyl functions form an alkali metal salt of the copolymer. 
These copolymers, when mixed with poly(ethylene terephthalate), are 
claimed to be effective in providing a composition that can be molded at 
temperatures below about 110.degree. C. and still produce a molded article 
having a smooth and glossy surface. However, these nucleating agents tend 
to produce degradation of the polyester during the molding process while 
the compositions containing them have a reduced melt index, making it 
harder to fill thin cross-sections in complicated shapes. 
In view of the ineffectiveness of the inorganic nucleating agents described 
in the prior art, our discovery that small amounts of certain solid, 
crystalline metal hydroxides produce an effective increase of the 
temperature of crystallization upon cooling from the melt (Tcc) of 
poly(ethylene terephthalate) (PET) and its analogs was therefore totally 
unexpected and fills an important need in the art of manufacturing 
articles of crystalline, saturated linear polyesters by molding the molten 
polymer composition. 
Additions of aluminum hydroxide powder to poly(1,4-butylene terephthalate) 
molding compositions in amounts of over 5% by weight have been disclosed 
as flame retardant fillers in Japanese Patent No. 75-109945. Example 4 of 
U.S. Pat. No. 3,544,523 describes the use of precipitated aluminum 
hydroxide as one of several inorganic anticaking agents in the solid state 
polymerization of poly(ethylene terephthalate), where the resin is 
maintained at 250.degree. C. for over 5 hours. 
In none of these inventions was the surprising effectiveness of crystalline 
aluminum hydroxide as a nucleating agent for the saturated, linear 
polyesters recognized, and the processes involved in the above-mentioned 
patents are substantially different from the process of the present 
invention. 
SUMMARY OF THE INVENTION 
This invention relates to a molding composition comprising: 
a. a thermoplastic, linear, saturated polyester of terephthalic acid, 
b. a plasticizer and 
c. a crystal nucleating agent, 
wherein the improvement consists in using as a nucleating agent a powdered 
crystalline metal hydroxide selected from the group of aluminum hydroxide, 
nickel hydroxide, indium hydroxide and copper hydroxide, in an amount 
sufficient to increase the crystallization temperature of the polyester 
composition in at least about 15.degree. C. with regard to that of the 
mixture of a and b. 
In addition, the composition may contain other ingredients commonly used in 
molding formulations and known to those skilled in the art, such as impact 
modifiers, mold release agents, chain extenders, lubricants, colorants, 
antioxidants, UV stabilizers, fillers and fiber reinforcement. 
The nucleating metal hydroxide c should be present as a fine powder with 
grain size not exceeding 45 microns. Preferably, the nucleating agent is 
present in an amount from 0.1% to 4% by weight of the polyester. In a 
preferred embodiment the polyester is poly(ethylene terephthalate), the 
plasticizer is neopentyldiol dibenzoate and the metal hydroxide is 
aluminum hydroxide in an amount of 1% by weight of poly(ethylene 
terephthalate). 
The present invention further relates to a process of molding linear, 
saturated polyester compositions from the melt by cooling in a water 
heated mold at temperatures not exceeding 110.degree. C. To accomplish 
this, the crystallization must begin at as high a temperature as possible. 
According to the present invention, this purpose is achieved by the 
addition, prior to molding, of a powdered, crystalline metal hydroxide as 
described in c hereinbefore, which causes a substantial decrease in the 
molding cycle and an increase in the Tcc of the polyester composition of 
at least about 15.degree. C. Tcc can be measured by Differential Scanning 
Calorimetry as described hereinafter. 
The present invention also relates to shaped articles made by molding a 
thermoplastic polyester composition as described in this specification, 
wherein the surface qualities are substantially improved with regard to 
those of an article produced in absence of the nucleating agents object of 
this invention. 
DETAILED DESCRIPTION OF THE INVENTION 
The composition of the present invention includes linear, saturated 
polyesters of terephthalic acid. The preferred linear, saturated 
polyesters include poly(ethylene terephthalate), poly(1,4-butylene 
terephthalate), poly(1,6-hexylene terephthalate) and 
poly(1,4-cyclohexylenedimethylene terephthalate) with poly(ethylene 
terephthalate) being most preferred. The poly(ethylene terephthalate) for 
use with the present invention has an intrinsic viscosity range between 
about 0.4 and about 1.00, with a preferred intrinsic viscosity range 
between about 0.60 and 0.95. Intrinsic viscosity is obtained by 
extrapolation of viscosity values to zero concentration of solutions of 
poly(ethylene terephthalate) in a 60 to 40 weight/volume ratio of phenol 
and tetrachloroethane. The measurements are normalized to 25.degree. C. 
The poly(ethylene terephthalate) can contain minor amounts, up to 5 
percent, of other comonomers such as 1,4-cyclohexane dimethanol, 
1,4-butanediol, neopentyldiol, diethylene glycol, glutaric acid or adipic 
acid. 
A plasticizer is included in the composition of the present invention. The 
plasticizer allows crystallization of amorphous areas of the poly(ethylene 
terephthalate) to continue at lower temperatures than if a plasticizer 
were not used. This is particularly important in low temperature molding 
where the mold temperature is below the temperature at which 
crystallization is expected to stop. This temperature for pure 
poly(ethylene terephthalate) is about 125.degree. C. 
The plasticizers which can be used with the composition of the present 
invention are of the type known in the art which can be used with linear 
saturated polyester molding compositions preferably poly(ethylene 
terephthalate). A nonlimiting group of plasticizers are the following 
organic esters. The organic esters can be the product of an aromatic 
carboxylic acid of 7-11 carbon atoms containing at least one carboxyl 
group per aromatic nucleus, and an alcohol selected from those of the 
formula (HOCH.sub.2) R'.sub.x wherein x is 1, 2 or 3 and R' is hydrocarbon 
radical of 2-15 carbon atoms (preferably 2-10 carbon atoms) or those of 
the formula HO(R"O).sub.y R"' wherein y is a cardinal number between 1 and 
8, R" is a hydrocarbon radical of 2-15 carbon atoms (preferably 2-8 carbon 
atoms) and R"' is --H or a hydrocarbon radical of 2-20 carbon atoms 
(preferably 2-12 carbon atoms). The plasticizer used can also be the 
product of an aliphatic carboxylic acid of 1 to 20 carbon atoms containing 
1-3 carboxyl groups, and an alcohol of the formula HO(R"O).sub.y R"', 
wherein R", R"' and y are defined above. Other plasticizers proposed for 
use with compositions object of this invention include the following: 
organic ketones of the formula 
##STR2## 
organic sulfones of the formula RSOOR; organic sulfoxides of the formula 
R.sub.2 SO; organic nitriles of the formula RCN; and organic amides of the 
formula 
##STR3## 
wherein R is a hydrocarbon radical group of 1-25 carbons, and R' is a 
hydrogen or hydrocarbon radical group of 1-25 carbon atoms. A preferred 
aliphatic plasticizer is dioctyl adipate, and a preferred aromatic 
plasticizer is neopentyldiol dibenzoate. Other aromatic plasticizers which 
can be used include: triethylene glycol dibenzoate, glyceryl tribenzoate, 
and pentaerythritol tetrabenzoate. In the present invention the amount of 
plasticizer added can be up to 15% by weight of the polyester. Preferably, 
there is between about 2% and 10% based on the weight of the poly(ethylene 
terephthalate) of plasticizer, and most preferably there is between about 
3% and about 8% of plasticizer based on the weight of the poly(ethylene 
terephthalate). 
The nucleating agents used in the present invention are solid crystalline 
metal hydroxides of the group consisting of aluminum hydroxide, nickel 
hydroxide, indium hydroxide and copper hydroxide. One or a mixture of 
these hydroxides can be used in the compositions encompassed by this 
invention. The hydroxides used are commercial grade products. In the 
examples they were sieved through mesh no. 325 which ascertains a grain 
size not greater than 45 microns, and were dried to a water content of 
less then 20 ppm. The preferred nucleating agents are aluminum hydroxide 
and nickel hydroxide; aluminum hydroxide being the most preferred. 
The aluminum hydroxide used in this invention is added to the formulation 
in its hydrated form. The hydrate contains 30.+-.5% water of hydration 
which is lost at the 275.+-.25.degree. C. temperature interval. Moisture 
regained by the dehydrated aluminum hydroxide is not effective in 
regenerating its nucleating capacity. Unless specifically indicated, the 
aluminum hydroxide mentioned in this specification is meant to be its 
hydrated form. 
Table I shows the effectiveness of different metal hydroxides for 
increasing the Tcc of poly(ethylene terephthalate) which for the 
unmodified resin is about 190.degree. C. 
TABLE I 
______________________________________ 
METAL HYDROXIDES AS 
NUCLEATING AGENTS FOR PET 
ALL AT 1% LEVEL, ALL DRIED AT 130.degree. C. 
T.sub.cc Normalized to 
Metal Hydroxide 
T.sub.cc .degree.C. 
I.V. I.V. = 0.50 
______________________________________ 
COPPER 208 0.68 217 
NICKEL 204 0.64 212 
INDIUM 209 0.55 212 
BARIUM 195 0.73 206 
MAGNESIUM 208 0.41 203 
______________________________________ 
Table II shows that further elimination of water by drying at temperatures 
above 250.degree. C. diminishes the nucleating capacity of aluminum 
hydroxide. This illustrates the distinctive character of the nucleating 
effect of these hydroxides with regard to that of alumina and other 
inorganic powders used as nucleating agents in the prior art. 
TABLE II 
______________________________________ 
EFFECT OF DRYING Al(OH).sub.3.(H.sub.2 O).sub.n AT DIFFERENT 
TEMPERATURES 
% T.sub.cc Normalized 
Resin Nucleator I. Viscos. T.sub.cc .degree.C. 
to I.V. = 0.50 
______________________________________ 
Al(OH).sub.3 dried at 130.degree. C. 
PET 1.00 0.61 210 216 
Al(OH).sub.3 dried at 280.degree. C. 
PET 1.00 0.56 203 205 
Al(OH).sub.3 dried at 325.degree. C. 
PET 1.00 0.67 202 210 
Al.sub.2 O.sub.3 type Porocel 
PET 1.00 0.79 196 211 
Al.sub.2 O.sub.3 type - alumina 
PET 1.00 0.68 194 205 
Without Nucleator 
PET 0.76 192 190 
______________________________________ 
As a general condition we have found that the excellent nucleating ability 
of the compounds here described coincides with a property shared by all of 
them, namely the discontinuous loss of water in the 250.degree. 
C.-300.degree. C. temperature range (melt processing range of PET), either 
by dehydration or decomposition, which leaves behind a residue that is 
inert to the polyester composition and inocuous to the environment. 
The nucleating agent is used in an amount sufficient to produce an increase 
of at least about 15.degree. C. in the T.sub.cc with regard to that of the 
composition without the nucleator. The measurement of the T.sub.cc is done 
on a sample of about 7 milligrams which is placed in a Differential 
Scanning Calorimeter and heated at 10.degree. C./min. from room 
temperature to 300.degree. C. It is held at 300.degree. C. for 5 minutes. 
The sample is then cooled at 10.degree. C./min. The T.sub.cc appears as a 
sharp peak on the cooling branch of the curve. 
The T.sub.cc for pure poly(ethylene terephthalate) having an intrinsic 
viscosity normalized to 0.50 is approximately 190.degree. C. The following 
table shows the T.sub.cc 's obtained with poly(ethylene terephthalate) of 
initial IV=0.95 and varying amounts of aluminum hydroxide. 
TABLE III 
______________________________________ 
EFFECT OF VARYING AMOUNTS OF ALUMINUM 
HYDROXIDE ON POLY(ETHYLENE TEREPHTHALATE) 
I.V. T.sub.cc Normalized* 
PET + Nucleator 
T.sub.cc of Product 
to I.V. = 0.50 
______________________________________ 
0.0% Al(OH).sub.3 
188 0.7 190.degree. C. 
0.5% Al(OH).sub.3 
204 0.56 207 
0.75% Al(OH).sub.3 
207 0.52 208 
1.00% Al(OH).sub.3 
210 0.61 216 
______________________________________ 
A variety of other nucleating agents can be used in combination with the 
metal hydroxide nucleators of this invention. For example, inorganic 
powders such as clays, calcium carbonate, carbon powder and the like, 
sodium stearate, sodium citrate, poly(alkylene oxides), and ionomers. 
The following table illustrates the combination of Al(OH).sub.3 and 
poly(ethylene oxide) as nucleator for poly(ethylene terephthalate). 
PEO.sub.1 has Mw=100,000, PEO.sub.2 has Mw=15,000-20,000. 
TABLE IV 
______________________________________ 
T.sub.cc 
I.V. of 
Normalized* 
Molded to I.V. = 
Polyester 
Nucleating Agents 
T.sub.cc 
Product 
0.50 
______________________________________ 
PET 0.75% Al(OH).sub.3 + 
211 0.77 226 
5% PEO.sub.1 
" 0.75% Al(OH).sub.3 
204 0.81 221 
" 1.00% Al(OH).sub.3 + 
207 0.81 224 
5% PEO.sub.1 
" 1.00% Al(OH).sub.3 
207 0.69 217 
" 0.75% Al(OH).sub.3 + 
207 0.79 223 
5% PEO.sub.2 
" 0.75% Al(OH).sub.3 
212 0.74 225 
" 1.00% Al(OH).sub.3 + 
206 0.80 223 
5% PEO.sub.2 
" 1.00% Al(OH).sub.3 
206 0.70 217 
" 0.50% Al(OH).sub.3 + 
207 0.74 219 
5% PEO.sub.2 
______________________________________ 
*In Tables III and IV, and in various other Tables and Examples that 
follow, measured T.sub.cc values have been normalized from the actual 
intrinsic viscosity (IV) to an intrinsic viscosity of 0.50 based upon the 
relationship between IV and T.sub.cc of sodium ionomer or carboxylic 
esternucleated PET. The T.sub.cc of aluminum hydroxidenucleated PET has 
been found, however, to be significantly less IVdependant than sodium 
ionomeror carboxylatenucleated PET, thus accounting for the substantially 
different "normalized" T.sub.cc values in Tables III and IV for similar 
compositions of different PET IV values. 
The compositions object of this invention may contain impact modifiers in 
an amount of up to 10%, and preferably from about 2% to about 6% based on 
the weight of the polyester resin. The impact modifiers that can be used 
include rubbery impact modifiers, e.g. polysiobutylene; high impact 
polystyrene (HIS); acrylonitrile-butadiene-styrene alloy (ABS); 
homopolymers of .alpha.,.beta.-unsaturated olefins; homopolymers of 
methacrylic esters; copolymers of .alpha.,.beta.-unsaturated olefins with 
.alpha.,.beta.-unsaturated carboxylic acids or esters such as 
ethylene-acrylic acid, ethylene-methacrylic acid, ethylene-ethyl acrylate, 
ethylene-vinyl acetate; polyamides and ionic polymers (ionomers) obtained 
by partially or totally neutralizing the pendant carboxylic groups of 
organic polymers by metal ions. Examples of preferred impact modifiers 
used in compositions of the present invention are copolymers of ethylene 
and acrylic acid and terpolymers of ethylene, isobutyl methacrylate and 
methacrylic acid in which part of the acid groups are neutralized by 
sodium or zinc ions. Other examples of preferred impact modifiers are 
poly(methyl methacrylate); ABS resin and poly(ethylene propylene 
butadiene). Mixtures of similar or dissimilar types of the above mentioned 
impact modifiers may also be used. 
We have found that the effect of the nucleating agent in increasing the 
T.sub.cc of the composition is enhanced when part of the hydroxide is 
incorporated into the ionomeric impact modifier. The exact nature of this 
effect is not understood, but it cannot be attributed merely to the 
neutralization of the ionomer by the aluminum ion. In comparative 
experiments wherein the free carboxylic acid groups of the ionomer were 
reacted with aluminum formate or with aluminum isopropionate, the effect 
of the ionomer-Al(OH).sub.3 mixture could not be reproduced. The data 
given in Table V illustrate the point. 
TABLE V 
______________________________________ 
EAA* neutralized 
T.sub.ch ** I.V. of 
Polyester with .degree.C. 
T.sub.cc .degree.C. 
Product 
______________________________________ 
PET IV = 0.5 
NaOH 120 213 0.48 
" Al formate 126 202 0.49 
" NaOH and Al 125 206 0.50 
formate 
______________________________________ 
*Ethylene acrylic acid copolymer 
**T.sub.ch = temperature of crystallization upon heating. 
Good impact modification is achieved with sodium ion percentage of 0.028% 
by weight of PET or lower, which is below the level of sodium at which the 
ionomer is said to affect the crystallization of PET according to Belgian 
Patent No. 874,469. 
The composition can contain a polyepoxide. The epoxy resins which can be 
used include an epoxy formed from bisphenol-A and glycidyl ether, or 
polyepoxides obtained by reacting orthocresol novolac and epichlorohydrin. 
Preferred polyepoxides are epoxy cresol novalac resins sold under the 
trademarks ECN 1235, 1273 and 1299 produced by the Ciba-Geigy Corporation. 
Preferably, there is up to about 3% and more preferably 0.5% to about 1.5% 
based on the weight of the poly(ethylene terephthalate) of polyepoxide. 
The polyepoxides act as chain extenders and help to compensate for 
poly(ethylene terephthalate) chains broken by hydrolysis. 
In addition to the components discussed above, the compositions of the 
present invention can contain additives commonly employed with polyester 
resins, such as colorants, mold release agents, antioxidants, flame 
retarding agents, ultraviolet light stabilizers and the like. 
Any suitable filler or reinforcing agent can be used. The fillers may 
optionally be treated with various coupling agents or adhesion promoters 
as is known to those skilled in the art. Examples of fillers include glass 
fibers, alumina, feldspar, asbestos, talc, calcium carbonates, clay, 
carbon black, quartz, novaculite and other forms of silica, kaolinite, 
bentonite, garnet, mica, saponite, beidellite, etc. The foregoing recited 
fillers are illustrative only and are not meant to limit the scope of the 
fillers that can be utilized in this invention. There is up to 150% by 
weight of the poly(ethylene terephthalate) of filler, and preferably about 
30% to about 90% by weight of the poly(ethylene terephthalate) of filler. 
The most preferred fillers are glass fibers.

The following examples are illustrative of molding compositions and 
procedures encompassed by the present invention. 
EXAMPLE 1 
A molding composition was prepared with the following ingredients: 
a. 1600 g poly(ethylene terephthalate) having intrinsic viscosity (IV) of 
0.95, 480 g fiberglass type 3540 and 16 g aluminum hydroxide were mixed 
and dried at 120.degree. C. to a water content of less than 20 ppm. 
b. 100 g EAA 455 neutralized with 8% by weight of aluminum hydroxide. EAA 
455 is an ethylene acrylic acid copolymer produced by Dow Chemical 
Corporation. 
c. 65 g Benzoflex.RTM. 312 mixed with 20 g Epoxy Cresol Novolac resin 1299. 
Benzoflex 312 is neopentyl diol dibenzoate. Epoxy 1299 is a polyfunctional 
epoxy resin having about 3 epoxy groups per molecule. It is manufactured 
by Ciba-Geigy Corporation. 
Ingredients a, b and c are mixed at about room temperature, passed through 
a single screw extruder at temperatures of between 265.degree. C. and 
275.degree. C., cooled in air stream and pelletized. 
EXAMPLES 2-6 
In the examples that follow Surlyn.RTM. 1855 and Surlyn.RTM. 1856 were used 
as impact modifiers. These are terpolymers of ethylene, methacrylic acid 
and isobutyl methacrylate in which part of the carboxylic functions are 
neutralized by zinc ions and sodium ions respectively. They are described 
in detail in the bulletin Surlyn Ionomer Resin E 1488 published by the 
DuPont Company. In a preferred embodiment of this invention the ground and 
dried ionomer resin is mixed with about 6% of its weight of powdered, 
vacuum dried aluminum hydroxide. The mixture is extruded and pelletized. 
The preparation of the molding composition is otherwise similar to that 
given in Example 1. 
TABLE VI 
______________________________________ 
Ex. Ex. Ex. Ex. Ex. 
2 3 4 5 6 
Ingredient % % % % % 
______________________________________ 
PET (IV = 0.53) 70.2 66.0 -- -- 
Pet (IV = 0.95) -- 70.2 61.3 62.5 
Fiberglass 21.0 21.0 29.4 29.8 30.4 
Aluminum hydroxide 
0.7 0.7 0.7 0.6 0.6 
Surlyn.RTM. 1855 + 5.5% Al(OH).sub.3 
4.4 4.4 -- -- -- 
Surlyn.RTM. 1856 + 5.5% Al(OH).sub.3 
-- -- -- 1.9 1.9 
EAA 455 + 5.5% Al(OH).sub.3 
-- -- -- 1.9 -- 
Benzoflex 312 2.8 2.8 3.9 3.7 3.8 
Epoxy ECN 1299 0.9 0.9 -- 0.8 0.8 
______________________________________ 
Extrusion was performed in a 3 zone extruder using a 3:1 screw operating at 
40 RPM. The temperature profile is preferably 260.degree. C. in zone 1 and 
2, and 265.degree. C. in zone 3. The two faces of the mold were set at 
temperatures below 110.degree. C. and the total molding cycle was 17 
seconds in examples 2 and 3, and 15 seconds in examples 4, 5 and 6. 
Table VII shows properties of molded articles obtained by the use of some 
of the formulations given. 
TABLE VII 
______________________________________ 
Ex. 3 Ex. 4 Ex. 5 Ex. 6 
______________________________________ 
IV of molded article 
0.86 0.58 0.57 0.57 
T.sub.cc of molded article .degree.C. 
209 208 208 212 
T.sub.cc normalized to IV = 0.50, 
229 212 211 216 
.degree.C. 
Breaking strength. PSI 
15560 19540 1 450 19340 
Breaking elongation % 
5.0 4.4 4.6 5.1 
Tensile modules PSI .times. 10.sup.6 
1.000 1.284 1.264 1.383 
Molding cycle sec. 
17 15 15 15 
______________________________________ 
Various mixtures, similar to that of Example 6 but with different impact 
modifiers, were also prepared, molded and tested for tensile (breaking) 
strength. Mixtures using as impact modifier either polymethylmethacrylate 
or poly(acrylonitrile-butadiene-styrene) (ABS) gave higher tensile 
strengths than the mixture of Example 6. A mixture using 
poly(ethylene-propylene-butadiene) gave a tensile strength slightly lower 
than the mixture of Example 6. Mixtures using polyethylene or 
ethylene-propylene rubber with 6% grafted acrylic acid gave lower and much 
lower tensile strengths than the mixture of Example 6. 
EXAMPLE 7 AND COMATIVE EXAMPLE 8 
Another feature of the present invention is the improvement in surface 
quality obtained in molded articles containing the novel nucleating agent. 
In example 7 and comparative example 8 the surface gloss of a molded 
article prepared with a composition containing aluminum hydroxide is 
compared with that of an article of identical composition from which 
aluminum hydroxide has been omitted. The test pieces were prepared in the 
same manner and under identical conditions as described for examples 1 
through 6. 
EXAMPLE 7 AND COMATIVE EXAMPLE 8 
Another feature of the present invention is the improvement in surface 
quality obtained in molded articles containing the novel nucleating agent. 
In example 7 and comparative example 8 the surface gloss of a molded 
article prepared with a composition containing aluminum hydroxide is 
compared with that of an article of identical composition from which 
aluminum hydroxide has been omitted. The test pieces were prepared in the 
same manner and under identical conditions as described for examples 1 
through 6. 
EXAMPLE 7 
800 g Poly(ethylene terephthalate) of initial IV=0.95 
389 g fiber glass 
8 g aluminum hydroxide 
50 g Surlyn.RTM. 1856 compounded with 6% of its weight of aluminum 
hydroxide 
48 g Benzoflex.RTM. 
10 g Epoxy 1299 
EXAMPLE 8 
800 g Poly(ethylene terephthalate) of initial IV=0.95 
389 g fiber glass 
50 g Surlyn.RTM. 1856 
48 g Benzoflex 
10 g Epoxy 1299 
Mold temperature for both formulations was 105.degree. C. The gloss of the 
test pieces was measured by means of a Hunterlab Colorimeter Model D 25P-2 
using the 60 degree angle optical unit of a Modular Glossmeter accessory. 
A total of 52 measurements showed readings of 41.+-.9 for Example 7 against 
18.+-.3 for Comparative Example 8. 
In test series 3-C.sub.1 through 3-C.sub.4 and 5-CA through 5-CG, the 
formulations of Example 7 and Comparative Example 8 were molded and 
subjected to comparative experiments in order to show the effect of 
molding conditions on compositions differing only in the presence of 
Al(OH).sub.3. The results are shown in Table VIII. 
TABLE VIII 
______________________________________ 
IV of Mold 
Compo- Molded Gloss Cycle Temp. 
sition Test Article T.sub.cc .degree.C. 
at 60.degree. 
sec. .degree.C. 
______________________________________ 
Example 8 
3-C.sub.1 
0.57 202 15.6 15 105 
C.sub.2 0.49 203 20.0 15 105 
C.sub.3 0.55 203 19.1 15 105 
C.sub.4 0.69 202 18.3 13 105 
Example 7 
5-CA 0.62 207 35.9 15 105 
CB 0.63 213 42.0 25 105 
CC 0.68 208 41.1 15 99 
CD 0.62 214 42.2 25 99 
CE 0.66 212 37.8 15 99 
CF 0.62 215 41.2 25 99 
CG 0.64 209 44.0 13 99 
______________________________________ 
In articles molded from the composition of Comparative Example 8 (test 
series 3-C.sub.1 through 3-C.sub.4), acceptable surface quality could not 
be obtained below 100.degree. C. In contrast, test series 5-CA through 
5-CG using the composition of Example 7 shows that neither the increased 
mold temperature, nor the increased molding cycle produces an improvement 
in the surface quality of the molded article, which is substantially 
better than that obtained without the nucleator. The gloss values are 
averages of 5 specimens obtained with the same equipment and method as 
described in the foregoing gloss comparison of Examples 7 and 8. 
EXAMPLE 9 AND COMATIVE EXAMPLE 10 
In the following series of experiments, Example 9 containing PET (initial 
IV=0.95), 30% by weight of PET of fiber glass, 6% by weight of PET of 
Benzoflex.RTM. plasticizer and 1% by weight of PET of aluminum hydroxide 
was compared with Example 10 of identical composition in which the 
aluminum hydroxide was omitted. They were extruded under the same 
conditions and molding under the same conditions was attempted but 
unsuccessful with the unnucleated formulation of Comparative Example 10. 
TABLE IX 
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T.sub.cc .degree.C. 
Molding 
Com- normalized 
Cycle 
position 
Conditions 
IV T.sub.cc .degree.C. 
to IV = 0.50 
sec 
______________________________________ 
Example 9 
Extruded 0.74 207 220 N/A 
Example 9 
Molded 0.58 208 212 15 
cond A 
Example 9 
Molded 0.53 208 210 20 
cond B 
Example 9 
Molded 0.55 207 210 15 
cond C 
Example 10 
Extruded 0.80 182 187 N/A 
Example 10 
Molded 0.75 189 192 could 
cond A not be 
ejected 
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The examples given in this specification describe the best mode of carrying 
out the invention but should not be construed as limiting in regard to 
composition or procedure, and obvious modifications may occur to those 
skilled in the art. 
The scope of the invention is to be determined from the following claims.