Copolyesters useful for fibers having high elongation and modulus contain minor amounts of ##STR1## units where Y is oxygen or carbonyl.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to certain fiberforming, melt-spinnable wholly 
aromatic copolyesters prepared from (a) 4-hydroxybenzoic acid, a 
hydroquinone, terephthalic acid and 4-hydroxy- or 
4-carboxy-3'(4"-hydroxybenzoyl)benzophenone or from (b) a hydroquinone, 
terephthalic acid and 4-hydroxy- or 
4-carboxy-3'(4"-hydroxybenzoyl)benzophenone. These copolyesters are useful 
for preparation of filaments having high break elongation and high 
modulus. They are also useful for extrusion molding or injection molding 
and for preparation of tough films. 
2. Description of the Prior Art 
Aromatic copolyesters capable of forming optically anisotropic melts are 
well known in the art. These polymers have yielded heat-treated fibers 
with combinations of high modulus and low break elongation. These 
properties are especially useful in tire cords or drive belts. On the 
other hand there are uses such as in nonwovens or in fiber/plastic 
composites which would benefit from a combination of high modulus and high 
break elongation. The preparation of anisotropic fiber-forming, 
melt-spinnable polyesters yielding fibers with modulus above 140 dN/tex 
and with elongation above 9% is a worthwhile objective. 
Anisotropic melt polymers containing units derived from diketodiols are 
disclosed in U.S. Pat. Nos. 4,226,970 and 4,269,965 but the desired 
combination of high modulus and high break elongation is not disclosed in 
these references. It is believed that differences in structure are 
responsible. 
SUMMARY OF THE INVENTION 
The present invention is directed to melt-spinnable copolyesters of 
fiber-forming molecular weight that exhibit optical anisotropy in the melt 
and consist essentially of (a) Units I, II, III and IV or (b) Units I, II 
and III, said units having the structural formulas: 
##STR2## 
where X is selected from the group consisting of hydrogen, halo- 
(preferably chloro-) or lower alkyl (preferably methyl), or aryl 
(preferably phenyl); Y is selected from the group consisting of oxygen and 
carbonyl; and wherein said copolyesters consisting essentially of Units I, 
II, III and IV contain from about 10 to 15 mole % of Unit I, from about 10 
to 20 mole % of Unit II, from about 10 to 15 mole % of Unit III and from 
about 50 to 70 mole % of Unit IV; and wherein said copolyesters consisting 
essentially of Units I, II and III contain from about 40 to 45 mole % of 
Unit I, from about 40 to 50 mole % of Unit II and from about 10 to 15 mole 
% of Unit III. In each case the number of dioxy units in the copolyester 
is substantially equal to the number of dicarbonyl units. 
One group of preferred copolyesters of the invention consists essentially 
of Units I, II, III and IV where in Unit I, X is hydrogen or chloro-. 
Other preferred copolyesters of the invention consist essentially of Units 
I, II and III where in Unit I, X is chloro- or phenyl-. Melt-spun and 
heat-strengthened filaments of such polyesters as well as films and molded 
or extruded articles from such polyesters are included in the invention. 
DETAILED DESCRIPTION OF THE INVENTION 
Unit I in the copolyesters of the invention is 1,4-dioxyphenylene, lower 
alkyl-, halo-, or aryl-1,4-dioxyphenylene. Methyl and phenyl groups 
exemplify the preferred lower alkyl and aryl groups, respectively. Unit II 
is the terephthaloyl radical. Unit III is the 
oxy-1,4-phenylene-carbonyl-1,3-phenylene-carbonyl-1,4-phenylene-oxy 
radical or the oxy-1,4-phenylene-carbonyl-1,3 
phenylene-carbonyl-1,4-phenylene-carbonyl radical. Unit IV is 
p-oxybenzoyl. 
The number of dioxy units present in the copolyester is substantially equal 
to the number of dicarbonyl units. Mole % is calculated on the basis of 
total moles of units present, i.e. [I+II+III+IV]. 
Suitable precursors for Unit I include hydroquinone or the corresponding 
substituted hydroquinones. This precursor is generally employed in the 
form of the diacetate. Terephthalic acid is a suitable precursor for Unit 
II while 4-hydroxybenzoic acid in the form of the monoacetate is useful 
for providing Unit IV. The diacetate of 
4-hydroxy-3'(4"-hydroxybenzoyl)benzophenone or the monoacetate of 
4-carboxy-3'(4"-hydroxybenzoyl)benzophenone can provide Unit III. 
J. Am. Chem. Soc. 60 pp 2283-2285 (October, 1938) discloses preparation of 
4-hydroxy-3'(4"-hydroxybenzoyl)benzophenone. The monoacetate of 
4-carboxy-3'(4"-hydroxybenzoyl)benzophenone is prepared as follows: 
97.0 g (0.40 mole) of 3(4'-hydroxybenzoyl)benzoic acid was condensed with 
37.0 g (0.40 mole) of toluene in a mixture of 200 g of HF and 95.0 g (1.40 
moles) of BF.sub.3 in a 1 liter Hastalloy.RTM. C shaker tube with 
agitation for 18 hours at 30.degree. C. The reaction mixture was poured 
onto ice, the product collected, washed with water, suspended in water and 
neutralized with aqueous ammonia to a pH of 7-8, collected again, dried, 
and recrystallized twice from ethanol/water (1/1 by volume) by dissolving 
in ethanol, filtering, then diluting with water to provide 
3(4"-hydroxybenzoyl)4'-methylbenzophenone. Melting point is 
175.5.degree.-176.degree. C. Calculated for C.sub.21 H.sub.16 O.sub.3 : C, 
79.7%; H, 5.10%. Found: C, 79.6%, H, 5.10%. 
3(4"-Hydroxybenzoyl)4'-methylbenzophenone (79.0 g, 0.25 mole) was oxidized 
with 53 g (0.53 mole) chromic anhydride (CrO.sub.3) in a mixture of acetic 
acid (500 ml), concentrated H.sub.2 SO.sub.4 (1.5 g) and acetic anhydride 
(178 g, 1.75 moles) in a flask equipped with stirrer, thermometer, 
condenser and portal for addition of ingredients. All ingredients except 
CrO.sub.3 were added, and the mixture stirred overnight, then at 
60.degree. C. again overnight, to ensure actylation of the phenolic group. 
The CrO.sub.3 was added in increments of about 10 g such that with 
intermittent cooling a temperature of 50.degree. C. was maintained. After 
subsequent addition of 200 ml more acetic acid and overnight stirring at 
ambient temperature, the reaction mixture was diluted to a total volume of 
2 liters with ice and water, stirred, the product collected, washed with 
water and dried. Crystallization twice from acetic acid yielded 71% of 
4-carboxy-3'(4"-acetoxybenzoyl)benzophenone, m.p., 241.degree.-242.degree. 
C. Calculated for C.sub.23 H.sub.16 O.sub.6 : C, 71.1; H, 4.15. Found: C, 
71.3; H, 4.31. 
The precursor reactants are generally combined in proportions corresponding 
to the molar proportions of the units desired in the copolyester products 
except that it is preferred to use a molar excess, indicated in the 
examples as (%) of the more volatile diacetate of hydroquinone, or 
substituted hydroquinone. 
Conventional polymerization techniques may be employed such as described in 
the aforementioned U.S. Pat. No. 4,118,372 and more particularly in the 
examples described below. In general, a mixture of monomers is heated with 
stirring, under nitrogen in a 250 ml 3-necked flask or polymerization tube 
in a Wood's metal bath or other suitable heating medium from approximately 
250.degree. C. to 330.degree.-380.degree. C. Polymerization is continued 
for up to a total of 0.5 to one hour or longer if necessary until a 
polymer of fiber-forming molecular weight is obtained. Usually a vacuum is 
applied to obtain a final product with high molecular weight. The 
copolyesters of the invention exhibit optical anisotropy in the melt as 
described in U.S. Pat. No. 4,118,372. 
FILAMENT PREATION 
The copolyesters of the invention are spun into filaments by conventional 
melt-spinning techniques without substantial degradation. In the examples 
below, filaments were prepared by melt-spinning into a quenching 
atmosphere of air or nitrogen and collected at a windup speed specified in 
the example. Melt pumping speed is adjusted to give the approximate linear 
density (D) shown in the tables at the stated windup rate. 
As used herein, the term "as-spun fiber" refers to a fiber which has not 
been drawn or heat treated after extrusion and normal windup. 
HEAT TREATMENT AND UTILITY 
Following collection, samples of undrawn (as-spun) monofilament were 
heat-treated in essentially relaxed condition in an oven as taught in 
Luise U.S. Pat. No. 4,183,895. Heating was in a purged nitrogen atmosphere 
with temperature increased in stages. Typically, temperature was raised 
from room temperature to 200.degree. C. in 2 hours, then to 304.degree. C. 
in another 7 hours, and finally maintained at 304.degree. C. for an 
additional 7 to 16 hours. The final temperature, which is usually the 
maximum temperature, is critical for achieving maximum break elongation 
and high modulus. 
The flow temperature of the filaments is a function of thermal history and 
molecular weight. Crystallization and molecular weight growth during heat 
treatment can increase the flow temperature of the filaments, making 
possible heat treatment temperatures in excess of the original polymer 
flow temperature. The maximum temperature for optimum development of high 
break elongation and high modulus should be close to or above the initial 
flow temperature, preferably above the initial flow temperature. Higher 
molecular weights favorably affect the development of high break 
elongation. Higher spin stretch factors also favor the development of high 
break elongation (determined from orifice diameter and tex as-spun). 
The heat treated fibers of this invention are useful for a variety of 
applications such as in ropes or in nonwoven sheets, but it is believed 
they are most useful in reinforcement of plastic composites where the 
composite is expected to absorb a high amount of energy under stress 
before failure. 
TEST METHODS 
Inherent viscosity (n.sub.inh), a measure of molecular weight, was computed 
from n.sub.inh =(ln n.sub.rel)/C where n.sub.rel is the relative viscosity 
and C is solution concentration in grams of polymer per deciliter of 
solvent. Relative viscosity is the ratio of polymer solution flow time to 
solvent flow time in a capillary viscometer at 30.degree. C. The solvent 
employed was a mixture of 7.5% trifluoroacetic acid/17.5% methylene 
chloride/12.5% dichlorotetrafluoroacetone hydrate/12.5% 
perchloroethylene/50% p-chlorophenol (all percentages by volume). The 
concentration was 0.5 g polymer per deciliter of solvent. 
The polymers were characterized by polymer flow temperature, meaning the 
lowest temperature at which polymer was observed to be molten, showing 
flow properties and allowing fibers to be drawn from the melt. The 
filament flow temperatures were determined as in U.S. Pat. No. 4,183,895, 
Col. 11. 
Monofilament tensile properties were measured in accordance with A.S.T.M. 
2101 Part 33 (1980) using a recording stress-strain analyzer at 70.degree. 
F. (21.1.degree. C.) and 65% relative humidity. Gauge length was 1.0 in 
(2.54 cm), and rate of elongation was 10%/min. Results are reported as 
D/T/E/M or T/E/M where D is linear density in tex units, T is breeak 
tenacity in dN/tex, E is elongation-at-break expressed as the percentage 
by which initial length increased, and M is initial tensile modulus in 
dN/text. Since linear density is normally substantially unchanged by 
heat-treatment, it is reported only for the as-spun filament. Average 
tensile properties for five filament samples are reported.

EXAMPLES 
The same general procedure was used in all the examples. It should be 
understood that the results reported below are believed to be 
representative of what can be obtained and do not constitute all the runs 
performed involving the indicated reactants. Unfamiliarity with the 
reaction requirements of the system, use of impure reactants or 
inappropriate heat treatment conditions may cause other results such as 
lower elongation or modulus to be obtained. 
In the examples, the diacetate of the dihydric phenols and the monoacetate 
of the hydroxyacid was used. The terephthalic acid was used as such rather 
than as esters or other derivatives. 
In the examples below, the following code is employed to identify the 
polymerization reactants or functional equivalents as well as the repeat 
units provided by such reactants. 
HQ--hydroquinone 
CHQ--chlorohydroquinone 
PHQ--phenylhydroquinone 
TPA--terephthalic acid 
HBA--4-hydroxybenzoic acid 
DKDH--4-hydroxy-3'(4"-hydroxybenzoyl)benzophenone 
DKHA--4-carboxy-3'(4"-hydroxybenzoyl)benzophenone 
The monomer ingredients were added in substantially the same molar ratios 
as desired in the final polymer except that an excess (usually 4 to 7%) of 
acetylated dihydric phenol was generally used. The resultant polymer is 
identified, for example, as CHQ/TPA/DKDH/HBA (10/20/10/60) meaning it 
contained 10 mole % of chloro-1,4-dioxyphenylene units (from the diacetate 
of chlorohydroquinone), 20 mole % of terephthaloyl units (from 
terephthalic acid), etc. (excesses of diacetates are not included in these 
percentages). 
The 3-necked flask or polymer tube was fitted with: (1) a glass stirrer 
extending through a pressure-tight resin bushing, (2) a nitrogen inlet, 
and (3) a short column leading to a water- or air-cooled condenser with a 
flask for collecting acetic acid by-product. An attachment for application 
of vacuum was provided at the end of the condenser. An electrically heated 
Wood's metal bath or a boiling liquid vapor bath mounted for vertical 
adjustment was used for heating. The reaction mixture was heated to 
increasing temperatures with stirring at atmospheric pressure under 
nitrogen purge until essentially all the acetic acid had evolved. Then, 
vacuum was applied and pressure was reduced gradually from atmospheric to 
less than 1 mm of mercury (133.3 Pa). Heating under vacuum at less than 1 
mm mercury pressure was then continued until viscosity had increased to a 
level believed satisfactory for melt-spinning. The cooled and solidified 
polymer was comminuted, and a portion was molded into a cylindrical plug 
for melt spinning. 
EXAMPLE 1 
Filaments from Copolyesters having the Composition CHQ/TPA/DKDH/HBA 
(10/20/10/60) 
A polyester was prepared by heating the following ingredients in a 3-necked 
flask as described previously: 
______________________________________ 
81.0 g 4-acetoxybenzoic acid 
(.450 mole) 
18.0 g chlorohydroquinone diacetate 
(.0787-mole) 
(7% excess) 
30.75 g 4-hydroxy-3'(4"-hydroxybenzoyl) 
benzophenone diacetate 
(.0764 mole) 
24.9 g terephthalic acid (.150 mole) 
______________________________________ 
In the above mixture it is assumed that all of the excess acetate should be 
provided through the chlorohydroquinone because of its greater volatility 
and tendency to distill. The flask was heated from 200.degree. to 
330.degree. C. in 32 min. Vacuum was then applied and the flask heated to 
345.degree. C. in 15 minutes. The resulting polymer softened at 
270.degree. C. and fibers could be pulled from a melt at 300.degree. C. 
The inherent viscosity was 1.46. Polymer flow temperature as measured in 
the thermo optical test of Schaefgen U.S. Pat. No. 4,118,372 was 
278.degree. C. 
The polymer was spun through a five-hole spinneret with orifices 0.23 mm in 
diameter and 1.60 mm in length with cell temperature 304.degree. C., 
spinneret temp 305.degree. C. and wind-up speed 914 meters/min. [1000 
ypm]. 
Properties of the as-spun filaments are shown in Table I along with 
properties of yarns heat-treated in a nitrogen atmosphere at various 
maximum temperatures. 
Yarns heated at a maximum 304.degree. C. had high break elongation (14.4%) 
and high modulus (183 dN/tex). 
TABLE I 
______________________________________ 
PROPERTIES OF FILAMENTS FROM 
CHQ/TPA/TKDH/HBA (10/20/10/60) 
Tex Initial 
per Tenacity Elongation 
Modulus 
Treatment Filament dN/tex at Break % 
dN/tex 
______________________________________ 
As-spun 0.47 2.4 1.2 275 
Max. temp. 298.degree. C. 
0.47 3.3 8.7 208 
Max. temp. 304.degree. C. 
0.45 3.4 14.4 184 
Max. temp. 325.degree. C. 
0.42 3.4 4.1 183 
______________________________________ 
The polymer of this example may be melt extruded as film or molded with 
heat and pressure into various shaped articles. 
EXAMPLE 2 
Repeating the Polymer of Example 1 with Higher Inherent Viscosity 
The polymerization of Example 1 was repeated using the same ingredients. 
The flask was heated from 200.degree. to 330.degree. C. in 30 minutes. 
Vacuum was then applied and heating was continued to 345.degree. C. in 53 
minutes. The inherent viscosity was 2.07, which is higher than in Example 
I. 
The polymer was melt spun through a five-hole spinneret having orifices 
0.36 mm in diameter and 0.23 mm in length with cell temperature 
367.degree. C. and spinneret temperature 371.degree. C. and a wind-up 
speed 183 m/min. 
Properties of the as-spun filaments are shown in Table 2. Properties after 
various maximum heat treatment temperatures are shown. Elongations above 
9% at break were obtained for all heat treatments with maximum temperature 
in the range 290.degree.-310.degree. C. Initial moduli for these filaments 
were 144 to 212 dN/tex. 
TABLE 2 
______________________________________ 
PROPERTIES OF FILAMENTS FROM 
CHQ/TPA/TKDH/HBA (10/20/10/60) SPUN 
FROM POLYMER WITH INHERENT VISCOSITY 2.07 
Tex Initial 
per Tenacity Elongation 
Modulus 
Treatment Filament dN/tex at Break % 
dN/tex 
______________________________________ 
As-spun 1.3 3.1 1.6 244 
Max. heat-treatment 
290.degree. C. 
1.2 4.2 11.3 144 
298.degree. C. 
1.3 4.0 27.6 212 
310.degree. C. 
1.3 3.6 14.8 192 
315.degree. C. 
1.2 3.6 7.6 203 
______________________________________ 
EXAMPLE 3 
Filaments from Copolyester having the Composition HQ/TPA/DKDH/HBA 
(10/20/10/60) 
A polyester was prepared by heating the following ingredients in a polymer 
tube as described earlier: 
______________________________________ 
21.6 g 4-acetoxybenzoic acid 
(.120 mole) 
8.2 g 4-hydroxy-3'(4"-hydroxybenzoyl) 
benzophenone diacetate 
(.0204 mole) 
(7.1% excess) 
4.07 g hydroquinone diacetate 
(.0210 mole) 
6.64 g terephthalic acid (.0400 mole) 
______________________________________ 
The tube was heated from 284.degree. C. to 346.degree. C. in 44 minutes. 
Vacuum was applied for another 40 minutes at 346.degree.-360.degree. C. 
Fibers could be pulled from the melt at 354.degree. C. Inherent viscosity 
was 1.43. The polymer was optically anisotropic in the melt. 
A filament was melt spun from a one-hole spinneret with a hole diameter of 
0.23 mm with a cell temperature of 358.degree. C. at a wind-up speed of 
549 m/min. As-spun properties and properties after heat-treatment are 
shown in Table 3. This polymer having hydroquinone in place of the 
chlorohydroquinone of Examples 1 and 2 still provided heat-treated fibers 
with high break elongation and modulus. 
TABLE 3 
______________________________________ 
PROPERTIES OF FILAMENTS FROM 
HQ/TPA/DKDH/HBA (10/20/10/60) 
Tex Initial 
per Tenacity Elongation 
Modulus 
Treatment Filament dN/tex at Break % 
dN/tex 
______________________________________ 
As-spun 0.71 1.2 0.8 46 
Heat treated: 
0.99 3.7 15.0 177 
25-200.degree. C., 2 hr. 
200-306.degree. C., 7 hr. 
304.degree. C., 7 hr. 
Heat treated: 
0.79 3.8 11.6 198 
25-235.degree. C., 2 hr. 
235-270.degree. C., 2 hr. 
235-270.degree. C., 2 hr. 
270-305.degree. C., 2 hr. 
305-320.degree. C., 16 hr. 
______________________________________ 
EXAMPLE 4 
Filaments from Copolyester having the Composition PHQ/TPA/DKDH (40/50/10) 
The following ingredients were charged to a polymer tube: 
______________________________________ 
22.5 g phenylhydroquinone diacetate 
(.0832 mole) 
(4.5% excess) 
8.2 g 4-hydroxy-3'(4"-hydroxybenzoyl) 
benzophenone diacetate 
(.0204 mole) 
16.6 g terephthalic acid (.100 mole) 
______________________________________ 
The tube was heated from 210.degree. to 350.degree. C. in 28 minutes. 
Vacuum was then applied and temperature continued at 350.degree. C. for 7 
min. Fibers could be pulled from the melt at 330.degree. C. The inherent 
viscosity was 1.20. 
A melt spun mono-filament was prepared from a spinneret having an orifice 
diameter of 0.23 mm with spinneret temperature at 260.degree. C. and 
wind-up speed at 549 m/min. Properties of the resulting filament varied 
depending upon maximum heat-treatment temperatures. Highest break 
elongation (11.4%) was obtained with the maximum heat-treatment 
temperature at 277.degree. C. as shown in Table 4. Heat treatment 
temperatures above and below 277.degree. C. gave fibers with lower values. 
TABLE 4 
______________________________________ 
PROPERTIES OF FILAMENTS FROM 
PHQ/TPA/DKDH (40/50/10) 
Tex Initial 
per Tenacity Elongation 
Modulus 
Treatment Filament dN/tex at Break % 
dN/tex 
______________________________________ 
As-spun 0.51 2.9 3.3 166 
Max. heat 
treatment temp: 
292.degree. C. 
0.50 4.0 8.6 144 
286.degree. C. 
0.50 4.2 9.9 159 
277.degree. C. 
0.50 4.0 11.4 160 
267.degree. C. 
0.41 3.3 6.9 148 
260.degree. C. 
0.47 3.7 6.0 163 
258.degree. C. 
0.55 3.0 3.4 152 
______________________________________ 
EXAMPLE 5 
Filaments from a Polyester having the Composition CHQ/TPA/DKHA/HBA 
(14/14/12/60) 
The following ingredients were heated in a polymer tube under a stream of 
dry nitrogen with stirring: 
______________________________________ 
5.65 g 4-carboxy-3'(4"-hydroxybenzoyl)- 
benzophenone acetate (.0145 mole) 
4.03 g chlorohydroquinone diacetate 
(.0176 mole) 
(4.8% excess) 
2.79 g terephthalic acid (.0168 mole) 
12.90 g 4-hydroxybenzoic acid acetate 
(.0716 mole) 
______________________________________ 
The tube was heated from 200.degree. to 350.degree. C. in 60 minutes; then 
vacuum was applied and heating was continued at 350.degree. C. for 5 
minutes. The polymer had an inherent viscosity of 1.91. Polymer flow 
temperature was 319.degree. C. It was optically anisotropic in the melt. 
A molded plug was heated to 308.degree. C. and melt spun through a 
spinneret orifice 0.23 mm in diameter at a temperature of 320.degree. C. 
with a wind-up speed of 549 m/min. 
Properties of the fibers as-spun and after heat treatment are given in 
Table 5. 
TABLE 5 
______________________________________ 
PROPERTIES OF FILAMENTS FROM 
CHQ/TPA/DKHA/HBA (14/14/12/60) 
Tex Initial 
per Tenacity Elongation 
Modulus 
Treatment Filament dN/tex at Break % 
dN/tex 
______________________________________ 
As-spun 0.59 2.5 1.3 267 
Heat treated: 
0.55 4.0 9.8 241 
200-275.degree. C., 7 hrs. 
275.degree. C., 16 hrs. 
______________________________________ 
EXAMPLE 6 
Filaments from Polyester having the Composition CHQ/TPA/DKHA (43/43/14) 
The following ingredients were heated in a polymer tube: 
______________________________________ 
5.49 g 4-carboxy-3'(4"-hydroxybenzoyl) 
benzophenone acetate (.0141 mole) 
10.32 g chlorohydroquinone diacetate 
(.0451 mole) 
(5% excess) 
7.14 g terephthalic acid (.0430 mole) 
______________________________________ 
The tube was heated from 210.degree. to 340.degree. C. in 65 min.; then 
vacuum was applied and heating was continued for 10 minutes at 340.degree. 
C. The resulting fiber had an inherent viscosity of 1.32. 
The material was melt-spun at 325.degree. C. with a wind-up speed of 549 
m/min. using a single orifice 0.23 mm in diameter and 1.60 mm long. The 
preferred heat-treatment method was to increase the temperature 
progressively from 200.degree. to 268.degree. C. in 7 hours and then to 
heat at 268.degree. C. for 16 hours in a purged nitrogen atmosphere. 
The fibers exhibited the following properties: 
______________________________________ 
As-spun 
Heat-treated 
______________________________________ 
Tex per filament 0.20 0.22 
Tenacity, dN/tex 2.0 3.4 
Elongation at break, % 
1.5 13.7 
Initial Modulus, dN/tex 
189 151 
______________________________________