Polyester molding compositions

This invention relates to a molded object prepared from a copolyester having an inherent viscosity of 0.4 to 1.1 dL/g, PA1 wherein the acid component comprises repeat units from 90 to 40 mole % terephthalic acid and from 10 to 60 mole % of one or more additional dibasic acids selected from the group consisting of isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and stilbenedicarboxylic acid; PA1 wherein the glycol component comprises repeat units from 1,4-cyclohexanedimethanol.

This invention relates to certain molded objects comprising 
poly(1,4-cyclohexylenedimethylene terephthalate) copolyesters which have 
improved toughness, clarity and stress crack resistance. 
BACKGROUND OF THE INVENTION 
Various polymeric materials have been widely used over the past 60 years 
for molding toothbrushes, tool handles, windshield scrapers, steering 
wheels, hair brushes, cutlery, eyeglass frames and the like. In many of 
these applications, the molded part must be clear, tough, impact 
resistant, stress crack resistant, hydrolysis resistant as well as having 
a pleasing feel and appearance. 
Plasticized cellulose acetate propionate (CAP) compositions have been used 
successfully in the past for toothbrush handles. Such compositions have 
good clarity, sparkle and overall appearance. However, design changes in 
toothbrush handles to increase the bristle density has led to cracking in 
certain brushes, The cracks which occur during bristle insertion are a 
result of insufficient weld-line strength. Increased plasticizer 
concentrations improve the weld-line strength but this leads to decreased 
stiffness which can result in inadequate bristle retention. 
Certain rigid polyurethane materials have been evaluated in this 
application but this polymer is difficult to mold, and the urethane 
linkages in the polymer chain can hydrolyze in the presence of moisture 
during molding. 
Polyester materials such as poly(ethylene terephthalate) (PET) and 
poly(1,4-cyclohexylenedimethylene terephthalate) (PCT) have many desirable 
properties for molded parts but these polymers are readily crystallizable 
and provide hazy or opaque objects when molded in thick parts. 
Modification of PET polymers with high levels of glycol components other 
than ethylene glycol provide clear, tough molded parts but they tend to 
stress crack in the presence of certain toothpaste solutions containing 
mint oil. 
For example, U.S. Pat. No. 2,901,466 (1959) assigned to Eastman Kodak 
Company describes a wide range of linear polyesters and polyesteramides 
derived from 1,4-cyclohexanedimethanol (CHDM). Many of the compositions 
are readily crystallizable and molded parts are hazy or opaque. Thus, they 
are not suitable for clear, molded objects. 
There is a need in the art, therefore, for molding compositions which have 
visual clarity and which have improved molding and physical property 
requirements. 
SUMMARY OF THE INVENTION 
This invention relates to molded objects prepared from a copolyester having 
an inherent viscosity of 0.4 to 1.1 dL/g, 
wherein the acid component comprises repeat units from 90 to 40 mole % 
terephthalic acid and from 10 to 60 mole % of one or more additional 
dibasic acids selected from the group consisting of isophthalic acid, 
cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, 
diphenyldicarboxylic acid, and stilbenedicarboxylic acid; and, 
wherein the glycol component comprises repeat units from 
1,4-cyclohexanedimethanol. 
These molded objects have the advantage of having improved clarity and 
stress crack resistance. They also have good physical properties including 
strength, stiffness, impact resistance and hydrolysis resistance.

DESCRIPTION OF THE INVENTION 
It has been found that certain PCT copolyesters are highly suitable for 
molding clear, tough, stress crack resistant parts. 
The molded objects are prepared from a copolyester having an inherent 
viscosity of 0.4 to 1.1 dL/g, 
where the acid component comprises repeat units from 90 to 40 mole %, 
preferably 85 to 52 mole %, more preferably, 83 to 52 mole % terephthalic 
acid and from 10 to 60 mole %, preferably 15 to 48 mole, preferably 17 to 
48 mole %, of one or more additional dibasic acids selected from the group 
consisting of isophthalic acid, cyclohexanedicarboxylic acid, 
naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 
stilbenedicarboxylic acid; 
where the glycol component comprises repeat units from 
1,4-cyclohexanedimethanol, preferably 80 to 100 mole % 
1,4-cyclohexanedimethanol, more preferably, 85 to 100 mole %, even more 
preferably 90 to 100 mole %, and even more preferably 95 to 100 mole %. 
When using the cyclohexanedicarboxylic acids, they may be in the cis or 
trans forms or as cis/trans isomer mixtures. The lower alkyl esters, such 
as the methyl esters, may be used instead of the dibasic acids in 
preparing the molding compositions of this invention. 
When cyclohexanedicarboxylic acid is used, 1,3- and 
1,4-cyclohexanedicarboxylic acid are preferred. When 
naphthalenedicarboxylic acid is used, 2,6-, 2,7-, 1,4-and 
1,5-naphthalenedicarboxylic acid are preferred. 
The molded objects of the invention, may comprise up to 10 mole % of even 
further additional dibasic acids. These dibasic acids may be selected from 
one or more of the group consisting of aromatic dicarboxylic acids, 
aliphatic dicarboxylic acids, and cycloaliphatic dicarboxylic acids, each 
preferably having 4 to 40 carbon atoms. More specifically, these 
additional dibasic acids can be selected from one or more of the group 
consisting of phthalic acid, cyclohexanediacetic acid, succinic acid, 
glutaric acid, adipic acid, azelaic acid, sebacic acid, isophthalic acid, 
cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, 
diphenyldicarboxylic acid, and stilbenedicarboxylic acid. 
Preferred additional carboxylic acids are selected from the group 
consisting of isophthalic acid, cyclohexanedicarboxylic acid, 
naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 
stilbenedicarboxylic acid. Even more preferred additional dibasic acids 
include isophthalic acid, cyclohexanedicarboxylic acid and 
naphthalenedicarboxylic acid. 
The glycol component may contain up to 20 mole % of one or more additional 
aliphatic or alicyclic glycols, preferably containing 2 to 20 carbon 
atoms. These additional glycols may be selected from the group consisting 
of ethylene glycol, diethylene glycol, triethylene glycol, propanediol, 
butanediol, pentanediol, hexanediol, neopentyl glycol and 
tetramethylcyclobutanediol. Ethylene glycol is particularly preferred. 
Very small amounts (less than 1.5 mole %) of certain branching agents such 
as trimellitic anhydride, trimellitic acid, pyromellitic dianhydride, 
trimesic acid, hemimellitic acid, glycerol, trimethylolpropane, 
pentaerythritol, 1,2,4-butanetriol, 1,2,6-hexanetriol, sorbitol, 
1,1,4,4-tetrakis(hydroxymethyl)cyclohexane, dipentaerythritol and the like 
may be used. 
The copolyesters of this invention are readily prepared using melt phase or 
solid state polycondensation procedures well known in the art. They may be 
made by batch or continuous processes. Examples of these processes can be 
found in U.S. Pat. Nos. 4,256,861, 4,539,390, and 2,901,466 and include 
preparation by direct condensation or by ester interchange. 
Specifically, the polymers of this invention may be prepared according to 
the methods described in U.S. Pat. No. 2,901,466. However, the preparation 
of the polymers of this invention is not particularly limited to the 
method described in U.S. Pat. No. 2,901,466. This patent discloses 
interchange reactions as well as polymerization build-up processes. 
Briefly, a typical procedure consists of at least two distinct stages; the 
first stage, known as ester-interchange or esterification, is conducted 
under an inert atmosphere at a temperature of 150.degree. to 250.degree. 
C. for 0.5 to 8 hours, preferably from 180.degree. to 240.degree. C. for 1 
to 4 hours. The glycols, depending on their reactivities and the specific 
experimental conditions employed, are commonly used in molar excesses of 
1.05-2.5 per total moles of acid-functional monomers. The second stage, 
referred to as polycondensation, is conducted under reduced pressure at a 
temperature of 230.degree. to 350.degree. C., preferably 265 to 
325.degree. C., and more preferably 270.degree. to 300.degree. C. for 0.1 
to 6 hours, preferably 0.25 to 2 hours. Stirring or appropriate conditions 
are used in both stages to ensure adequate heat transfer and surface 
renewal of the reaction mixture. The reactions of both stages are 
facilitated by appropriate catalysts, especially those well-known in the 
art, such as alkoxy titanium compounds, alkali metal hydroxides and 
alcoholates, salts of organic carboxylic acids, alkyl tin compounds, metal 
oxides, and so forth. 
Suitable copolyesters will have inherent viscosity (I.V.) values of about 
0.4 to about 1.1 dL/g. Such values are obtained in a 60/40 
phenol/tetrachlorethane solution containing 0.5 grams (g) of polymer in 
100 milliliters (mL) of solution. It is preferred that the copolyesters 
have I.V. values of at least 0.5 dL/g. 
Preferred copolyesters must have glass transition temperatures (Tg) of at 
least 70.degree. C. as determined by Differential Scanning Calorimetry 
(DSC) and a crystallization half-time of at least 1 minute as measured by 
a small angle laser light scattering technique. 
The technique for determining the crystallization haze half-times consists 
primarily in following the increase in depolarization of plane-polarized 
light by the polyester. The method used in this invention is primarily 
that shown in "A New Method for Following Rapid Rates of Crystallization", 
I. Poly (hexamethylene adipamide), J. H. Magill, Polymer, Vol. 2, page 
221-233 (1961) with the exception that Magill uses a polarizing microscope 
as the source of light and light-collection lenses. In measuring the 
crystallization half-times of the present invention, a helium-neon laser 
[with a small angle light scattering technique (SALS)] was used as was 
shown by Adams and Stein in J. Polymer Sci. A2, Vol. 6 (1962). 
Crystallization half-times are measured at the time in which the 
transmitted intensity is half of the maximum intensity achieved. 
The method used is generally as follows: 
(1) Melt the sample to remove existing crystallinity; 
(2) Crystallize the sample polyester at a predetermined temperature; 
(3) Record the transmitted light intensity plotted versus time; 
(4) Find the time at which the transmitted intensity is half of the maximum 
intensity achieved. 
The above procedure is repeated at different temperatures until a minimum 
value for the crystallization half-time can be measured. "Minimum value" 
refers to the lowest measurable point on a curve plotted using the 
temperature data and corresponding crystallization half-time data. 
The term "crystallization haze half-time as measured from the melt phase" 
as defined herein is the procedure as describe above. 
It is preferred that the molded objects of the invention have a 
crystallization haze half-time of greater than 1 minute, preferably 
greater than 3 minutes, and more preferably greater than 5 minutes. 
When the molded objects of the invention have crystallization haze 
half-times as described, they are generally visually clear for regions of 
a molded object having a thickness of from 1 to 11.5 mm, preferably 3 to 
11.5." 
It is also preferable that molded objects prepared from the blends of the 
invention have a diffuse transmittance value of less than about 60%, more 
preferably, less than about 40%, and more preferably, less than about 20% 
as determined by ASTM Method D1003. When the diffuse transmittance value 
is less than about 60%, the molded objects are visually clear. 
Also, the molded objects of the invention demonstrate improved stress 
cracking resistance as determined for test specimens which are 0.32 
centimeters thick under a flexural load with 1.4% strain and with 2.7% 
strain and as demonstrated more fully in the following Examples. 
This stress cracking resistance testing is preferably performed in the 
presence of a flavorant. More preferably, the flavorant is a mint oil. Of 
the possible mint oils, it is preferable that the mint oil is either 
peppermint oil or spearmint oil. 
The stress cracking resistance measurements used in the invention are also 
preferably performed in the presence of a toothpaste solution comprising 
water and a toothpaste containing greater than 0.6 weight % mint oil or, 
more specifically, in the presence of peppermint oil directly as described 
more fully in the following Examples. 
Other ingredients may be used in the toothpaste solutions including 
glycerine, sodium bicarbonate, water, hydrated silicate, polyethylene 
glycol, sodium laural sulfate, sodium laural sarcosinate, sodium 
pyrophosphates, sodium phosphates, sorbitol, sodium benzoate, sodium 
saccharin, xantham gum, cellulose gum, flavorants, sodium saccharin, FD&C 
blue #1 and FD&C yellow #10, FD&C red 30, 1-hydroxy-2-propanone, 
3-octanol, 4-methyl-1-(1-methylethyl)cyclohexene, pulegone, dodecanol, 
3-phenyl-2-propenal, dodecanol, eugenol and titanium dioxide. 
Flavorants useful in performing the tests of the invention include 
peppermint oil, curly mint oil, anise oil, Japanese anise oil, caraway 
oil, eucalyptus oil, fennel oil, cinnamon oil, clove oil, geranium oil, 
sage oil, pimento oil, thyme oil, and majoram oil. 
Mint oil may contain several ingredients including, but not limited to: 
limonene, cineole, menthone, menthol, and carvone. 
The copolyesters may be used in clear form or they may be colored or 
pigmented with additives or copolymerizable colorants. Typically useful 
copolymerizable colorants are described in U.S. Pat. Nos. 5,030,708 
(1991), 5,102,980 (1992) and 5,194,571 (1993) all assigned to Eastman 
Kodak Company, incorporated herein by reference. 
Other additives such as stabilizers, antioxidants, mold release agents, 
fillers and the like may also be used if desired. Polymer blends may be 
used. 
The copolyesters of this invention are easy to mold into desired shapes 
such as toothbrush handles, hair brush handles, ice scrapers, cutlery or 
cutlery handles, tool handles, automotive steering wheels, eyeglass frames 
and the like. This invention can be further illustrated by the following 
examples of preferred embodiments thereof, although it will be understood 
that these examples are included merely for purposes of illustration and 
are not intended to limit the scope of the invention unless otherwise 
specifically indicated. The starting materials are commercially available 
unless otherwise indicated. Percentages are by weight unless otherwise 
stated. 
I. PREATION OF COPOLYESTERS AND MOLDED OBJECTS 
Example 1--Comparative--Preparation of Copolyesters containing 
terephthalate, ethylene glycol and 3 mole % 1,4-cyclohexanedimethanol 
A 5000 mL stainless steel reactor equipped with an agitator shaft, nitrogen 
inlet, and an outlet to allow for removal of volatile materials was 
charged with 679.7 grams (3.5 mole) of dimethyl terephthalate (DMT), 427.8 
grams (6.9 mole) of ethylene glycol (EG), 16.4 grams (0.11 mole) of 
1,4-cyclohexanedimethanol (CHDM) (70% trans isomer/30% cis isomer) and 
1.35 mL of a 3.30% (w/v) solution of titanium (IV) isopropoxide in 
n-butanol. The reactor was purged with nitrogen and heated to 200.degree. 
C. under a slow nitrogen sweep with agitation and held for one hour. The 
reactor temperature was raised to 220.degree. C. and held for two hours. 
The temperature was raised to 280.degree. C. and the nitrogen purge was 
removed and a vacuum was applied such that a vacuum of &lt;0.5 mm was 
attained over a 30 minute period. The reactor was stirred under vacuum for 
one hour. The vacuum was then displaced with a nitrogen atmosphere and the 
polymer was extruded through an opening in the bottom of the reactor. The 
extruded rod was cooled in an 5.degree. C. water bath and pelletized. The 
recovered polymer pellets had an inherent viscosity of 0.70 deciliters 
(dL)/g according to ASTM D3835-79. The diol component of the polymer 
consisted of 96 mole % EG, 3 mole % CHDM and 1 mole % diethylene glycol 
(DEG) as measured by gas chromatography on a hydrolyzed sample. A glass 
transition temperature (T.sub.g) of 78.degree. C. and a melting point 
(T.sub.m) of 248.degree. C. were measured by DSC (differential scanning 
calorimetry) analysis. The crystallization haze half-time as measured from 
the melt phase was 0.8 minutes. The sample was dried at 150.degree. C. in 
a dehumidifier drier for about 4 hours and injection molded into clear 
plaques that were 7.5 centimeters (cm) square and 0.32 cm thick. Located 
approximately 1 cm from the plaque edge was an area 1.1, cm by 0.6 cm 
which contains twelve holes approximately 0.1 cm in diameter as shown in 
FIG. 1. This area of the plaque was used to simulate the head of a 
toothbrush into which bristles would be inserted. 
Example 2--Comparative--Preparation of Copolyester containing 
terephthalate, EG and 31 mole % CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 679.5 grams (3.5 mole) 
DMT, 365.6 grams (5.9 mole) EG, 160.4 grams (1.1 mole) CHDM and 2.05 mL of 
a 3.30% (w/v) solution of titanium isopropoxide in n-butanol. The diol 
interchange step was conducted at 200.degree. C. for one hour and at 
210.degree. C. for two hours. The polycondensation step was conducted at a 
vacuum of 0.5 mm Hg for one hour. The polymer was extruded from the bottom 
of the reactor. The extruded rod was cooled in an 5.degree. C. water bath 
and pelletized. The recovered polymer pellets had an inherent viscosity of 
0.74 dL/g. The diol component of the polymer consisted of 68 mole % EG, 31 
mole % CHDM and 1 mole % DEG. The amorphous copolymer possessed a T.sub.g 
of 80.degree. C. as determined by DSC analysis. The crystallization haze 
half-time as measured from the melt phase was greater than 1 hour. The 
sample was dried at 65.degree. C. in a dehumidifier drier for about 16 
hours. It was injection molded into clear specimens set forth in Example 
1. 
Example 3--Comparative--Preparation of Copolyester containing 
terephthalate, EG and 62 mole % CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 679.7 grams (3.5 mole) 
DMT, 305.6 grams (4.9 mole) EG, 302.5 grams (2.1 mole) CHDM and 2.06 mL of 
a 3.30% (w/v) solution of titanium isopropoxide in n-butanol. The diol 
interchange step was conducted at 200.degree. C. for one hour and at 
210.degree. C. for two hours. The polycondensation step was conducted at a 
vacuum of 0.5 mm Hg for 45 minutes. The polymer was extruded from the 
bottom of the reactor. The extruded rod was cooled in an 5.degree. C. 
water bath and pelletized. The recovered polymer pellets had an inherent 
viscosity of 0.72 dL/g. The diol component of the polymer consisted of 37 
mole % EG, 62 mole % CHDM and 1 mole % DEG. A T.sub.g of 82.degree. C. and 
a T.sub.m of 225.degree. C. were obtained for the copolymer by DSC 
analysis. The crystallization haze half-time as measure from the melt 
phase was 28 minutes. The sample was dried at 65.degree. C. in a 
dehumidifier drier for about 16 hours and injection molded into clear 
specimens set forth in Example 1. 
Example 4--Comparative--Preparation of Copolyester containing 
terephthalate, EG and 81 mole % CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 679.2 grams (3.5 mole) 
DMT, 248.1 grams (4.0 mole) EG, 432.9 grams (3.0 mole) CHDM and 2.38 mL of 
a 3.30% (w/v) solution of titanium isopropoxide in n-butanol. The diol 
interchange step was conducted at 200.degree. C. for one hour and at 
210.degree. C. for two hours. The polycondensation step was conducted at a 
vacuum of 0.5 mm Hg for 40 minutes. The polymer was extruded from the 
bottom of the reactor, cooled in an 5.degree. C. water bath and 
pelletized. The recovered polymer pellets had an inherent viscosity of 
0.76 dL/g and the diol component of the polymer consisted of 18 mole % EG, 
81 mole % CHDM and 1 mole % DEG. A T.sub.g of 87.degree. C. and a T.sub.m 
of 257.degree. C. were obtained for the copolymer by DSC analysis. The 
crystallization haze half-time as measured from the melt phase was 3 
minutes. The sample was dried at 150.degree. C. in a dehumidifier drier 
for about 4 hours and injection molded into clear specimens set forth in 
Example 1. 
Example 5--Comparative--Preparation of Copolyester containing 95 mole % 
terephthalate, 5 mole % isophthalate and CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 645.2 grams (3.3 mole) 
DMT, 34.1 grams (0.2 mole) dimethyl isophthalate (DMI), 555.7 grams (3.9 
mole) CHDM and 2.68 mL of a 3.30% (w/v) solution of titanium isopropoxide 
in n-butanol. The reactor was purged with nitrogen and heated to 
300.degree. C. under a slow nitrogen sweep with agitation. The reactor 
temperature was held for 30 minutes and then the nitrogen purge was 
removed and a vacuum was applied such that a vacuum of &lt;0.5 mm Hg was 
attained over a 30 minute period. The vacuum and temperature was held for 
50 minutes. The polymer was extruded from the bottom of the reactor. The 
extruded rod was cooled in an 5.degree. C. water bath and pelletized. The 
recovered polymer pellets had an inherent viscosity of 0.78 dL/g and the 
polymer consisted of 95 mole % terephthalate and 5 mole % isophthalate as 
measured by .sup.1 H NMR. A T.sub.g of 92.degree. C. and a T.sub.m of 
287.degree. C. were obtained for the copolymer by DSC analysis. The 
crystallization haze half-time as measured from the melt phase was 0.5 
minutes. The sample was dried at 150.degree. C. in a dehumidifier drier 
for about 4 hours and injection molded into clear specimens set forth in 
Example 1. 
Example 6--Example of the Invention--Preparation Copolyester Containing 83 
Mole % terephthalate, 17 Mole % isophthalate and CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 577.3 grams (3.0 mole) 
DMT, 101.9 grams (0.5 mole) DMI, 565.4 grams (3.9 mole) CHDM and 2.67 mL 
of a 3.30% (w/v) solution of titanium isopropoxide in n-butanol. The 
reactor was purged with nitrogen and heated to 290.degree. C. under a slow 
nitrogen sweep with agitation. The reactor temperature was held for 30 
minutes and then the nitrogen purge was removed and a vacuum was applied 
such that a vacuum of &lt;0.5 mm Hg was attained over a 30 minute period. The 
vacuum and temperature was held for 43 minutes. The polymer was extruded 
from the bottom of the reactor, cooled in an 5.degree. C. water bath and 
pelletized. The recovered polymer pellets had an inherent viscosity of 
0.70 dL/g and the polymer consisted of 83 mole % terephthalate and 17 mole 
% isophthalate as measured by .sup.1 H NMR. A T.sub.g of 89.degree. C. and 
a T.sub.m of 262.degree. C. were obtained for the copolymer by DSC 
analysis. The crystallization haze half-time as measured from the melt 
phase was 1.5 minutes. The sample was dried at 150.degree. C. in a 
dehumidifier drier for about 4 hours and injection molded into clear 
specimens set forth in Example 1. 
Example 7--Example of the Invention--Preparation of Copolyester containing 
70 mole % terephthalate, 30 mole % isophthalate and CHDM 
The apparatus and procedure set, forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 476.3 grams (2.5 mole) 
DMT, 204.1 grams (1.0 mole) DMI, 555.8 grams (3.9 mole) CHDM and 2.67 mL 
of a 3.30% (w/v) solution of titanium isopropoxide in n-butanol. The 
reactor was purged with nitrogen and heated to 290.degree. C. under a slow 
nitrogen sweep with agitation. The reactor temperature was held for 30 
minutes and then the nitrogen purge was removed and a vacuum was applied 
such that a vacuum of &lt;0.5 mm Hg was attained over a 30 minute period. The 
vacuum and temperature was held for 53 minutes. The polymer was extruded 
from the bottom of the reactor. The extruded rod was cooled in an 
5.degree. C. water bath and pelletized. The recovered polymer pellets had 
an inherent viscosity of 0.70 dL/g and the polymer consisted of 70 mole % 
terephthalate and 30 mole % isophthalate as measured by .sup.1 H NMR. An 
amorphous polymer was recovered that had a Tg of 87.degree. C. as measured 
by DSC. The crystallization haze half-time as measured from the melt phase 
was 6.8 minutes. The sample was dried at 65.degree. C. in a dehumidifier 
drier for about 4 hours and injection molded into clear specimens set 
forth in Example 1. 
Example 8--Example of the Invention--Preparation of Copolyester containing 
61 mole % terephthalate, 39 mole % 1,4-cyclohexanedicarboxylate and CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 404.7 grams (2.1 mole) 
DMT, 243.6 grams (1.4 mole) of dimethyl 1,4-cyclohexanedicarboxylate 
(DMCD) (35% trans isomer/65% cis isomer), 580.4 grams (4.03 mole) of CHDM 
and 2.65 mL of a 3.30% (w/v) solution of titanium isopropoxide in 
n-butanol. The reactor was purged with nitrogen and heated to 220.degree. 
C. for 60 minutes under a slow nitrogen sweep with sufficient agitation. 
After raising the temperature to 290.degree. C. the nitrogen purge was 
removed and a vacuum was applied such that a vacuum of &lt;0.5 mm Hg was 
attained in 30 min. The vacuum and temperature was held for 120 minutes to 
perform the polycondensation. The vacuum was then displaced with a 
nitrogen atmosphere and the polymer was drained from the bottom of the 
reactor, cooled in an 5.degree. C. water bath and pelletized. An inherent 
viscosity of 0.70 dL/g was determined for the recovered polymer. The 
polymer contained 61 mole % terephthalate and 39 mole % 
1,4-cyclohexanedicarboxylate (51% trans isomer/49% cis isomer) as measured 
by .sup.1 H NMR. A T.sub.g of 72.degree. C. and a T.sub.m of 223.degree. 
C. were obtained for the copolymer by DSC analysis. The crystallization 
haze half-time as measured from the melt phase was 15 minutes. The sample 
was dried at 65.degree. C. in a dehumidifier drier for about 4 hours and 
injection molded into clear specimens set forth in Example 1. 
Example 9--Example of the Invention--Preparation of Copolyester containing 
52 mole % terephthalate, 48 mole % 1,4-cyclohexanedicarboxylate and CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 404.7 grams (2.1 mole) 
of dimethyl terephthalate (DMT), 243.6 grams (1.4 mole) of dimethyl 
1,4-cyclohexanedicarboxylate (95% trans isomer/5% cis isomer), 580.4 grams 
(4.03 mole) of CHDM and 2.68 mL of a 3.30% (w/v) solution of titanium 
isopropoxide in n-butanol. The reactor was purged with nitrogen and heated 
to 290.degree. C. under a slow nitrogen sweep with agitation. The reactor 
temperature was held for 30 minutes and then the nitrogen purge was 
removed and a vacuum was applied such that a vacuum of &lt;0.5 mm was 
attained over a 30 minute period. The vacuum and temperature was held for 
53 minutes. The polymer was extruded from the bottom of the reactor 
through an orifice. The extruded rod was cooled in an 5.degree. C. water 
bath and pelletized. An inherent viscosity of 0.74 dL/g was determined for 
the recovered polymer. The polymer contained 52 mole % terephthalate and 
48 mole % 1,4-cyclohexanedicarboxylate (88% trans isomer/12% cis isomer) 
as measured by .sup.1 H NMR. A glass transition temperature T.sub.g of 
78.degree. C. and a T.sub.m of 225.degree. C. were obtained for the 
polymer by DSC analysis. The crystallization haze half-time as measured 
from the melt phase was 11.5 minutes. The sample was dried at 65.degree. 
C. in a dehumidifier drier for about 4 hours and injection molded into 
clear specimens set forth in Example 1. 
Example 10--Example of the Invention--Preparation of Copolyester containing 
70 mole % terephthalate, 30 mole % 2,6-naphthalenedicarboxylate and CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 477.0 grams (2.5 mole) 
DMT, 203.9 grams (1.0 mole) DMI, 565.4 grams (3.9 mole) CHDM and 2.67 mL 
of a 3.30% (w/v) solution of titanium isopropoxide in n-butanol. The 
reactor was purged with nitrogen and heated to 290.degree. C. under a slow 
nitrogen sweep with agitation. The reactor temperature was held for 30 
minutes and then the nitrogen purge was removed and a vacuum was applied 
such that a vacuum of &lt;0.5 mm was attained over a 30 minute period. The 
vacuum and temperature was held for 43 minutes. The polymer was extruded 
from the bottom of the reactor. The extruded rod was cooled in a 5.degree. 
C. water bath and pelletized. The recovered polymer pellets had an 
inherent viscosity of 0.64 dL/g and the polymer consisted of 70 mole % 
terephthalate and 30 mole % naphthalate as measured by .sup.1 H NMR. A 
T.sub.g of 103.degree. C. and a T.sub.m of 246.degree. C. were obtained 
for the polymer by DSC analysis. The crystallization haze half-time as 
measured from the melt phase was 9 minutes. The sample was dried at 
85.degree. C. in a dehumidifier drier for about 4 hours and injection 
molded into clear specimens set forth in Example 1. 
Example 11--Example of the Invention--Preparation of Copolyester containing 
68 mole % terephthalate, 32 mole % 1,4-cyclohexanedicarboxylate and CHDM 
The apparatus and procedure set forth in Example 1 was used. The following 
amounts of reactants were charged to the reactor: 461.8 grams (2.4 mole) 
of dimethyl terephthalate (DMT), 224.0 grams (1.1 mole) of dimethyl 
1,4-cyclohexanedicarboxylate (95% trans isomer/5% cis isomer), 580.4 grams 
(4.03 mole) of CHDM and 2.68 mL of a 3.30% (w/v) solution of titanium 
isopropoxide in n-butanol. The reactor was purged with nitrogen and heated 
to 290.degree. C. under a slow nitrogen sweep with agitation. The reactor 
temperature was held for 30 minutes and then the nitrogen purge was 
removed and a vacuum was applied such that a vacuum of &lt;0.5 mm was 
attained over a 30 minute period. The vacuum and temperature was held for 
50 minutes. The polymer was extruded from the bottom of the reactor 
through an orifice. The extruded rod was cooled in an 5.degree. C. water 
bath and pelletized. An inherent viscosity of 0.70 dL/g was determined for 
the recovered polymer. The polymer contained 68 mole % terephthalate and 
32 mole % 1,4-cyclohexanedicarboxylate (89% trans isomer/11% cis isomer) 
as measured by .sup.1 H NMR. A glass transition temperature T.sub.g of 
82.degree. C. and a T.sub.m of 245.degree. C. were obtained for the 
polymer by DSC analysis. The crystallization haze half-time from the melt 
was 2 minutes. The sample was dried at 65.degree. C. in a dehumidifier 
drier for about 4 hours and injection molded into clear specimens set 
forth in Example 1. 
II. PREATION FOR AND PERFORMANCE OF STRESS CRACKING RESISTANCE METHODS 
USING PEPPERMINT OIL AND TOOTHPASTE SOLUTION 
A. Preparation of Toothpaste Solution 
A toothpaste solution using Toothpaste A as described in the following 
Tables was prepared using the following procedure. In a 500 ml container, 
50 grams of solid toothpaste was added 120 ml of plain tap water. The 
mixture was sealed and then stirred using a magnetic stirring bar and a 
magnetically driven stirring plate. After a 30 minute mixing time the 
dispersion was applied to the test specimens using an applicator brush and 
observed. The same toothpaste solution Was used throughout each testing 
cycle. The following morning the test specimens from Examples 1-10 were 
inspected and ranked on their appearance using the craze ranking system. 
Crazes are precursors to cracks which form due to the interaction of the 
solvent with the polymer matrix. Crazes are similar to cracks, but crazes 
contain highly oriented fibrils of polymer which span its faces. Crazes 
are not necessarily structural defects, but often lead to the formation of 
true cracks. After the ranking, the test specimens were wetted with the 
toothpaste solution. The specimens were wet with the toothpaste solution 8 
hours later and observed the following morning. 
The stress crack resistance to pepper mint oil was determined using the 
same methodology as the toothpaste solution testing. 
Peppermint oil has the following composition: 
______________________________________ 
Peppermint Oil Composition 
Compound Weight Percent 
______________________________________ 
Dimethylsulfide 0.02 
2 Methyl propanal 
0.03 
3 methyl propanal 
&lt;0.01 
2 Methyl butanal &lt;0.01 
3 Methyl butanal 0.15 
2 Ethyl furan 0.03 
trans-2,5-Diethyl THF 
0.02 
.alpha.-Pinene 0.66 
Sabinene 0.42 
Myrcene 0.18 
.alpha.-Terpinene 
0.34 
Limonene 1.33 
1,8 Cineole 4.80 
trans-Ocimene 0.03 
cis-Ocimene 0.31 
G-Terpinene 0.56 
trans-2-Hexenal 0.07 
para-Cymeme 0.10 
Terpeniolene 0.16 
Hexanol 0.13 
3 Octyl acetate 0.03 
cis-3-Hexenol 0.01 
3-Octanol 0.21 
trans-2-Hexenol 0.02 
Sabinene hydrate 0.80 
Menthone 20.48 
Menthofuran 1.67 
D-Isomenthone 2.77 
B-Bourbonol 0.37 
Neomenthylacetate 
0.21 
Linalool 0.26 
cis-Sabinene hydrate 
0.07 
Menthyl acetate 5.02 
Isopulegol 0.07 
Neoisomenthyl acetate 
0.26 
Neomenthol 3.34 
.beta.-Caryophyllene 
2.13 
Terpinene-4-ol 0.98 
Neoisoisopulegol 0.03 
Neoisomenthol 0.78 
Menthol 43.18 
Pulegone 0.77 
tran-.beta. Farenscene 
0.29 
Isomenthol 0.19 
Humelene 0.03 
.alpha.-Terpineol 
0.16 
Germacrene-D 2.29 
Piperitone 0.96 
Viridiflorol 0.26 
Eugenol 0.02 
Thymol 0.04 
______________________________________ 
B. Toothpaste and Peppermint Oil Resistance Testing of Molded Articles 
Plaques molded from Examples 1-10 were mounted in a testing rig shown in 
FIG. 2. In FIG. 2 the parts labelled A are clamps to hold the test 
specimen, B is the curved portion of the rig which determines the strain 
the test specimens are under and C is the molded plaque under strain. The 
testing rig was configured such that the flexural strain on each specimen 
is 2.7%. The testing rigs were used to simulate end-use conditions such as 
bristle insertion. The specimens remained in the testing rigs for 7 days 
and observed each day for the formation of crazes. A ranking system from 
1-3 was used to identify the severity of crazing on each specimen, (visual 
observation codes as referred to herein). In this system, visual 
observation code 1 was assigned to test plaques that exhibit no change 
during the testing period. As the severity of crazing increases the 
ranking increases in value. 
Table 1 illustrates the effect of 2.7% flexural strain on the test 
specimens fabricated from pellets of Examples 1-5. No effect was observed 
on all test specimens. This indicates that placement of the test specimens 
in the testing apparatus does not induce crazing. 
The effect of the toothpaste solution on Examples 1-5 under flexural strain 
are shown in Table 2. The data in Table 2 indicates that as the CHDM 
content of the copolyesters is increased relative to the EG content the 
resistance to stress cracking of the test specimen improves. At high 
levels of CHDM as illustrated by Examples 4 and 5, no effect was observed. 
The same trend was observed when peppermint oil was used as the chemical 
agent as shown in Table 3. 
The data in Tables 2 and 3 indicate that Examples 4 and 5 have superior 
resistance to stress cracking when exposed to toothpaste solution and 
peppermint oil under flexural strain than Examples 1-3. Examples 3, 4 and 
5 were injection molded into cylindrically shaped articles that were 
approximately 20 cm in length. The diameter of each article varied between 
5 and 11.5 mm. The molded articles prepared from Example 3 were clear 
throughout. The molded articles prepared from Examples 4 and 5 were not 
completely clear. They contained opaque sections, generally in the area of 
the article with the largest diameter. This result indicated that the 
copolyesters represented by Examples 4 and 5 are resistance to stress 
cracking however; molded articles with thick sections of materials in 
Examples 4 and 5 were not preferred. 
In Table 4, the effect of 2.7% flexural strain on specimens fabricated from 
Examples 6-10 is shown. The data in Table 4 indicates that placement of 
the test specimens in the testing apparatus does not induce crazing. The 
data in Table 5 indicates that the plaques molded from Examples 6-10 do 
not show any effect when tested under flexural strain in the presence of 
toothpaste solution. The data in Table 6 indicates that Examples 6-10 all 
show improved stress crack resistance to peppermint oil under flexural 
strain than Examples 1-3. Pellets from Examples 6-10 were injection molded 
into cylindrically shaped articles 20 cm long. The diameter of each 
article varied between 5 and 11.5 mm. The molded articles prepared from 
Example 6 contained opaque sections particularly in the thickest sections, 
while the articles prepared from Examples 7-10 were clear throughout. This 
result indicates that certain copolyesters can be used to produce molded 
articles with thick sections that have excellent clarity and are 
resistance to stress cracking by toothpaste and peppermint oil. 
Pellets from Example 6 were injection molded into cylindrically shaped 
articles 20 cm long. The diameter of each article varied between 5 and 7 
mm. The molded articles were clear throughout. This result indicates that 
certain copolyesters can be used to produce molded articles that have 
excellent clarity and are resistant to stress cracking by toothpaste and 
peppermint oil. 
TABLE 1 
______________________________________ 
Effect of 2.7% Flexural Strain on Copolyesters Without 
Use of Toothpaste A Solution or Peppermint Oil 
Time Example Example Example 
(hrs.) 
1 2 3 Example 4 
Example 5 
______________________________________ 
18 1 1 1 1 1 
42 1 1 1 1 1 
66 1 1 1 1 1 
90 1 1 1 1 1 
162 1 1 1 1 1 
186 1 1 1 1 1 
______________________________________ 
Visual Observation Codes: 
1 = No effect 
2 = test specimen is lightly crazed. Crazes are shallow and randomly 
located 
3 = test specimen is heavily crazed. Crazes are deep and randomly located 
TABLE 2 
______________________________________ 
Effect of Toothpaste A Solution on Copolyesters at 2.7% 
Flexural Strain 
Time Example Example Example 
(hrs.) 
1 2 3 Example 4 
Example 5 
______________________________________ 
18 3 3 3 1 1 
42 3 3 3 1 1 
66 3 3 3 1 1 
90 3 3 3 1 1 
162 3 3 3 1 1 
186 3 3 3 1 1 
______________________________________ 
Visual Observation Codes: 
1 = No effect 
2 = test specimen is lightly crazed. Crazes are shallow and randomly 
located 
3 = test specimen is heavily crazed. Crazes are deep and randomly located 
TABLE 3 
______________________________________ 
Effect of Peppermint Oil on Copolyesters at 2.7% Flexural 
Strain 
Time Example Example Example 
(hrs.) 
1 2 3 Example 4 
Example 5 
______________________________________ 
2 3S 3S 3S 2 2 
18 3S 3S 3S 2 2 
42 3S 3S 3S 2 2 
66 3S 3S 3S 2 2 
90 3S 3S 3S 2 2 
114 3S 3S 3S 2 2 
______________________________________ 
Visual Observation Codes: 
1 = No effect 
2 = test specimen is lightly crazed. Crazes are shallow and randomly 
located 
3 = test specimen is heavily crazed. Crazes are deep and randomly located 
S = test specimen swelled 
TABLE 4 
__________________________________________________________________________ 
Effect of 2.7% Flexural Strain on Copolyesters Without the Use of 
Toothpaste Solution or Peppermint Oil 
Time 
(hrs.) 
Example 6 
Example 7 
Example 8 
Example 9 
Example 10 
Example 11 
__________________________________________________________________________ 
18 1 1 1 1 1 1 
42 1 1 1 1 1 1 
66 1 1 1 1 1 1 
90 1 1 1 1 1 1 
162 1 1 1 1 1 1 
186 1 1 1 1 1 1 
__________________________________________________________________________ 
Visual Observation Codes: 
1 = No effect 
2 = test specimen is lightly crazed. Crazes are shallow and randomly 
located 
3 = test specimen is heavily crazed. Crazes are deep and randomly located 
TABLE 5 
______________________________________ 
Effect of Toothpaste A Solution on Copolyesters at 2.7% 
Flexural Strain 
Time Example Example Example 
(hrs.) 
6 7 8 Example 9 
Example 10 
______________________________________ 
18 1 1 1 1 1 
42 1 1 1 1 1 
66 1 1 1 1 1 
90 1 1 1 1 1 
162 1 1 1 1 1 
186 1 1 1 1 1 
______________________________________ 
Visual Observation Codes: 
1 = No effect 
2 = test specimen is lightly crazed. Crazes are shallow and randomly 
located 
5 = test specimen is heavily crazed. Crazes are deep and randomly located 
TABLE 6 
______________________________________ 
Effect of Peppermint Oil on Copolyesters at 2.7% Flexural 
Strain 
Time Example Example Example 
(hrs.) 
6 7 8 Example 9 
Example 10 
______________________________________ 
1 2 2 3S 2 2 
22 2 2 3S 2 3 
46 2 2 3S 2 3 
70 2 2 3S 2 3 
94 2 2 3S 2 3 
118 2 2 3S 2 3 
______________________________________ 
Visual Observation Codes: 
1 = No effect 
2 = test specimen is lightly crazed. Crazes are shallow and randomly 
located 
3 = test specimen is heavily crazed. Crazes are deep and randomly located 
S = test specimen swelled 
Comparison of Tensile Strength of Molded Articles Before and After Exposure 
to Toothpaste Solution 
In Tables 7 and 8, the effect of the toothpaste solutions on retained 
tensile strength are displayed. Pellets of the examples listed in the 
tables were molded into tensile bars of 0.32 cm thickness as per ASTM 
method D638. One sample of the bars was tested as per ASTM D638 without 
any exposure to the toothpaste solution to establish a control standard. 
Additional bars were held in the strain rig described in the previous 
section at flexural strains of either 1.4% and 2.7%. The toothpaste 
solution was applied to these bars for one week as described in the 
previous section. After exposure, the bars were removed from the rig and 
tested per ASTM D638. The ratio of tensile strength of the exposed 
specimen to the tensile strength of the control standard multiplied times 
100% is the percent retained strength. Any Example which shows a retained 
strength of more than 90%, preferably, more than 95%, more preferably, 
more than 98%, and even more preferably, 100%, is deemed to possess 
sufficient chemical resistance for toothbrush applications. 
The data in Table 7 confirm that Examples 1-3 possess inferior chemical 
resistance after exposure to Toothpaste A. The data in Table 8 show how 
increasing the flavorant level in the toothpaste affect Examples 2, 3, 6 
and 11. The flavorant level was determined to be the total percentage of 
Limonene, Cineole, Methone, Menthol and Carvone, as determined by gas 
chromatography combined with mass spectroscopy. The levels of these 
components are also listed in Table 8. These five components are the chief 
compounds present in peppermint and spearmint oils. Levels of other 
components are listed in Table 9. 
TABLE 7 
______________________________________ 
Percentage of Retained Strength* 
@ 1.4% Flexural 
@ 2.7% Flexural 
Example Strain Strain 
______________________________________ 
1 30 27 
2 0 0 
3 38 0 
4 98 98 
5 100 100 
6 100 100 
7 100 100 
8 100 100 
9 100 100 
10 100 100 
11 100 100 
______________________________________ 
TABLE 8 
__________________________________________________________________________ 
Example 2 
Example 3 
Example 6 
Example 11 
Percent 
VO Code* 
VO Code* 
VO Code* 
VO Code* 
By Weight 
(% Retained 
(% Retained 
(% Retained 
(% Retained 
Flavorant 
Strength) 
Strength) 
Strength) 
Strength) 
__________________________________________________________________________ 
Toothpaste A* 
0.800% 
3 (0%) 1 (100%) 
1 (100%) 
Toothpaste B* 
0.475% 
1 (97%) 
2 (98%) 
1 (100%) 
1 (100%) 
Toothpaste C* 
0.685% 
2 (81%) 
2 (98%) 
1 (100%) 
1 (100%) 
Toothpaste D* 
0.480% 
2 (67%) 1 (100%) 
1 (100%) 
Toothpaste E* 
0.845% 
3 (0%) 3 (0%) 1 (100%) 
1 (100%) 
Toothpaste F* 
0.740% 
3 (0%) 1 (100%) 
1 (100%) 
__________________________________________________________________________ 
Flavorant Compositions by Weight Percentages for Toothpastes A-F: 
Limonene 
Cineole 
Menthone 
Menthol 
Carvone 
Total 
__________________________________________________________________________ 
Toothpaste A: 
&lt;0.01 0.02 0.105 0.67 0.01 0.800 
Toothpaste B: 
0.02 &lt;0.01 0.01 0.215 0.23 0.475 
Toothpaste C: 
&lt;0.01 0.015 0.09 0.57 0.01 0.685 
Toothpaste D: 
0.01 &lt;0.01 0.05 0.31 0.11 0.480 
Toothpaste E: 
0.02 0.035 0.245 0.465 0.08 0.845 
Toothpaste F: 
0.02 0.035 0.19 0.485 0.01 0.740 
__________________________________________________________________________ 
VO Code* = Visual Observation Code 
TABLE 9 
__________________________________________________________________________ 
CONCENTRATION (WEIGHT %) OF OTHER COMPOUNDS DETECTED 
IN TOOTHPASTES BY GAS CHROMATOGRAPHY/MASS SPECTROSCOPY 
Comp. 
Comp. 
Comp. 
Comp. 
Comp. 
Comp. 
Comp. 
Comp. 
Comp 
Comp 
Glycerin 
1 2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
Toothpaste A 
21.62 
0.01 0.025 
0.025 
0.085 
0.275 
0.115 0.07 
Toothpaste B 
18.06 0.01 
0.055 
0.155 0.55 
0.01 
Toothpaste C 
9.52 0.02 0.095 
0.175 
0.11 
0.06 
0.03 
Toothpaste D 
8.98 0.07 
0.01 
0.01 0.065 
0.275 0.105 
0.05 
0.05 
Toothpaste E 
21.67 
0.05 
0.01 
0.05 
0.025 
0.01 
0.28 0.13 0.08 
Toothpaste F 
12.15 
0.04 
0.01 
0.04 0.04 
0.14 0.065 0.01 
__________________________________________________________________________ 
Compound (Comp.) Identification 
1 1HO-2-Propanone 
2 3Octanol 
3 4Methyl-1-(1-methylethyl)cyclohexene 
4 Pulegone 
5 Dodecanol (isomer 1) 
6 Dodecanol (isomer 2) 
7 3Phenyl-2-propenal 
8 Dodecanol (isomer 3) 
9 Eugenol 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within, the spirit and scope of the 
invention. Moreover, all patents, patent applications (published and 
unpublished, foreign or domestic), literature references or other 
publications noted above are incorporated herein by reference for any 
disclosure pertinent to the practice of this invention.