WO1985002622A1

WO1985002622A1 - Color stabilized compositions of polycarbonate-polyester compositions and method of stabilization

Info

Publication number: WO1985002622A1
Application number: PCT/US1984/001992
Authority: WO
Inventors: Roger W. Avakian; Ronald Edward Jodice
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1983-12-14
Filing date: 1984-12-06
Publication date: 1985-06-20
Anticipated expiration: 1986-06-14
Also published as: EP0167564A1; JPS61500667A

Abstract

Compositions of aromatic polycarbonate homopolymers and copolymers and polyesters or copolyesters are stabilized against yellowing by including a small amount, from 0.01 to 1.00 percent by weight, or phosphorous acid, phenyl phosphonic acid, or a fluoroalkyl derivative of phosphorous acid. Both compositions and method are disclosed.

Description

COLOR STABILIZED COMPOSITIONS OF POLYCARBONATE-POLYESTER COMPOSITIONS^" AND METHOD OF STABILIZATION

BACKGROUND OF THE INVENTION

Aromatic polycarbonate resins and polyester resins based the reaction of diols with diacids have constituted two classes of engineering thermoplastics separately useful to prepare shaped articles, as by molding, extrusion, and so forth. In recent years interest has grown in combining these polymers with blends to provide certain property profiles not usually found with use of either polymer alone. A shortcoming often associated with such polymer blends is the forma- tion of yellow color, however.

The reasons for the color formation, or yellow¬ ing, appear to be several. It has been attributed to the thermal degradation of one or more of the polymers at the elevated temperatures of formation or processing. Another possible reason is the presence, depending on how the polymer is formed, of metallic catalyst residues in the polymer. Still another possibility is the fact of bringing together the two polymers which appears to cause a degradation interaction. It has been proposed in the patent literature that these polymer blends can be stabilized against color formation by including certain phosphorus-contain¬ ing compounds. These are described in U.S. Patent No. 3,953,539 (Kawase, et al.) and British Patent No. 1,569,296. Also of interest is Seymour., et al., U.S. 4,088,709, which describes the stabilizing effect of trivalent phosphorus compounds without mention of bene¬ ficial effect on color stability.. - . INTRODUCTION TO THE INVENTION The discovery has now been made that certain phosphorus-containing materials, such as phosphorous acid, aryl phosphonic acid and fluorocarbon-substituted derivatives of phosphorous acid, can be added in very small amounts to blends of aromatic polycarbonates and polyesters to achieve better color stability. The results can actually be better than what is achieved with use of some phosphites. This invention thus comprises two facets: blend compositions which have been color stabilized with the aforementioned phosphorus compounds, and a method for imparting color stability to a thermoplastic molding composition comprising the inclusion of such phosphorus compounds in a blend of two or more thermoplastic polymers.

DETAILED DESCCRIPTION OF THE INVENTION The compositions of the invention, in their broadest aspects, will comprise a thermoplastic admix¬ ture of (a) an aromatic polycarbonate, an aromatic poly(ester-carbonate) , an aromatic dihydric phenol sulfone carbonate, or a mixture of any. of the foregoing, in combination with

(b) a polyester resin -comprising units of an aliphatic diol, aliphatic ether diol, a cycloaliphatic diol, or a mixture of such diols and an aromatic and/or cycloaliphatic diacid; and

(c) a color stabilizing amount of a (i) phos¬ phorus-containing compound of the formula

0 ιr

HO P OH

where Y is hydrogen or phenyl, or (ii) a phosphorus- containing compound of the formula

0

II

(R CH CH ) - P (OH) 2 m n

where R = F(CF CF ) , n and m being independently 1 f 2 2 t or 2, and t being an integer from 3 to 8, or a mixture of the two.

In a preferred embodiment, component (a) comprises an aromatic polycarbonate, especially a poly (bisphenol A carbonate) and (b) comprises a poly(alkylene terephthalate)resin, especially poly(l,4-butylene tere- phthalate) . In another preferred embodiment, component (a) comprises a poly(ester-carbonate) and component (b) comprises a copolyester based on isophthalic and tere- phthalic acid with an aliphatic diol. In still another preferred embodiment, component (a) is an aromatic di- hydric phenol sulfone resin, especially a copolymer of a sulfone and bisphenol A prepared with phosgene. All of these are made more resistant to color formation by the inclusion of a small amount of ^"a phosphorus compound as described above, and preferably phosphorous acid.

With respect to component (a), this can comprise an aromatic polycarbonate resin, whicch can be made by those skilled in the art or can be obtained from a variety of commercial sources. They may be prepared by reacting a dihydric phenol with a carbonate precursor, such as phosgene, a haloformate or a carbonate ester. Typically, they will have recurring structural units of the formula:

wherein A is a divalent aromatic radical of the dihydric phenol employed in the polymer producing reaction. Pre¬ ferably, the aromatic carbonate polymers have an intrinsic viscosity ranging from 0.30 to 1.0 dl./g. (measured in methylene chloride at 25°C.) By dihydric phenols is meant mononuclear or polynuclear aromatic compounds con¬ taining two hydroxy radicals, each of which is attached to a carbon atom of an aromatic nucleus. Typical dihydric phenols include 2,2-bis-(4-hydroxy-phenyl)propane; 2-2- bis-(3,5-dimethyl-4-hydroxyphenyl)propane, 4,4"-dihydroxy- diphenyl ether, bis(2-hydroxyphenyl)methane, mixtures thereof and the like. The preferred aromatic carbonate polymer for component (a) is a homopolymer derived from 2,2-bis(4-hydroxy-phenyl)propane(bisphenol-A) .

Poly(ester-carbonates) for use in the invention are known and can be obtained commercially. Generally, they are copolyesters comprising recurring carbonate groups:

carboxylate groups:

aromatic carbocyclic groups in the linear polymer chain, in which at least some of the carboxylate groups and at least some of the carbonate groups are bonded directly to ring carbon atoms of the aromatic carbocyclic groups. These poly(ester-carbonate) copolymers, in general, are prepared by reacting a difunctional ca boxylic acid, such as phthalic acid, isophthalic acid, terephthalic acid, homophthalic acid, o-, m-, and p-phenylenediacetic acid, the polynuclear aromatic acids, such as diphenic acid, 1,4-naphthalic acid, mixtures of any of the fore¬ going, and the like, with a dihydric phenol and a car¬ bonate precursor, of the types described above. A par¬ ticularly useful polyester carbonate is derived from bisphenol-A, isophthalic acid, terephthalic acid, or a mixture of isophthalic acid and terephthalic acid, or the reactive derivatives of these acids such as tere- phthaloyl di-chloride, isophthaloyl dichloride, or a mixture thereof, and phosgene. The molar_.proportions of dihydroxy diaryl units to benzenedicarboxylate units to carbonate units can range from 1:0.30-0.80:0.70-0.20 and the molar range of terephthalate units to isophthalate units can range from 9:1 to 2:8 in this preferred family of resins.

The aromatic dihydric phenol sulfone resins used in component (a) are a family of resins which can

OM be made by those skilled in this art. For example, homopolymers of dihydric phenol, and a dihydroxydiphenyl sulfone and a carbonate precursor can be prepared as well as copolymers of a dihydric. henol and a carbonate precursor can be made according to the description in Schnell, et al., U.S. 3,271,367. A preferred material is made by polymerizing bis-(3,5-dimethyl-4-hydroxy phenyl) sulfone, alone, or especially in combination with bisphenol A with phosgene or a phosgene precursor, in accordance with the description in Fox, U.S. 3,737,409. Especially preferred is a copolymer made by reacting 40 to 99 wt. percent of the sulfone and 1 to 60 wt. percent of the bisphenol with phosgene.

With respect to component (b), polyesters suitable for use herein are derived from an aliphatic, aliphatic ether or cycloaliphatic diol, or mixtures thereof, containing from 2 to about 10 carbon atoms and at least one aromatic dicarboxylic acid. Preferred polyesters are derived from an aliphatic diol and an aromatic dicarboxylic acid and have repeated units of the following general formula:

wherein n is an integer of from 2 to 4. The most pre¬ ferred polyester is poly(ethylene terephthalate) .

Also contemplated herein are the above poly- esters with minor amounts, e.g., from 0.5 to about 2 percent by weight, of units derived from aliphatic acid and/or aliphatic polyols, to form copolyesters. The aliphatic polyols include glycols, such as poly(ethylene glycol). All such polyesters can be made following the teachings of, for example, U.S. Patent Nos. 2,465,319 and 3,047,539.

The polyesters which are derived from a cyclo¬ aliphatic diol and an aromatic and/or cycloaliphatic dicarboxylic acid are prepared, for example, by condensing either the cis- or trans-isomer (or mixtures thereof) of, for example, 1,4-cyclohexanedimethanol with an aromatic dicarboxylic acid so as to produce a polyester having recurring units of the following formula:

wherein the cyclohexane ring is selected from the cis- and trans-isomers thereof and R represents an aryl or cycloaliphatic radical containing 6 to 20 carbon atoms and which is the decarboxylated residue derived from an aromatic dicarboxylic acid.

Examples of aromatic dicarboxylic acids repre- sented by the decarboxylated residue R are isophthalic or terephthalic acid, l,2-di(p-carboxyphenyl)ethane, 4,4'-dicarboxydiphenyl ether, etc., and mixtures of these. All of these acids contain at least one aromatic nucleus. Acids containing fused rings can also be present, such as in 1,4- or 1,5-naphthalenedicarboxylic acids. Also contemplated are cycloaliphatic diacids, such as cyclohexane dicarboxylic acid. The preferred dicarboxylic acids are terephthalic acid or a mixture of terephthalic and isophthalic^" acids. Another preferred polyester may be derived from the reaction of either the cis- or trans-isomer (or a mixture thereof) of 1,4-cyclohexandimethanol with a mixture of isophthalic and terephthalic acids. Such a polyester would have repeating units of the formula: .

Still another preferred polyester is a copoly- ester derived from a cyclohexane dimethanol, an alkylene glycol and an aromatic dicarboxylic acid. These copoly¬ esters are prepared by condensing either the cis- or trans-isomer (or mixtures thereof) of, for example, 1,4- cyclohexane-dimethanol and an alkylene glycol with an aromatic dicarboxylic acid so as to produce a copoly- ester having units of the following formulae:

wherein the cyclohexane ring is selected from the cis- and trans-isomers thereof, R is as previously defined, n is an integer of 2 to 4, the x units comprise from about 10 to about 90 percent by weight and the y units comprise from about 90 to about 10 percent by weight.

Such a preferred copolyester may be derived from the reaction of either the cis- or trans-isomer (or mixtures thereof) of 1,4-cyclohexanedimethanol and ethylene glycol with terephthalic acid in a molar ratio of 1:2:3. These copolyesters have repeating units of the following formula:

wherein x and y are as previously defined.

Also included within this invention are polyesters derived from aliphatic ether diols, for example, tetraethylene diol, and diacids.

The polyesters described herein are either commercially available or can be produced by methods well known in .the art, such as those set forth in, for example, U.S. Patent No. 2,901,466. The polyesters used herein have an intrinsic viscosity of from about 0.4 to about 2.0 dl/g. as measured in a 60:40 phenol/tetrachloroethane mixture or similar solvent at 23°-30°C.

The relative amounts of components (a) and (b) can vary widely in the present blends. For instance, component (a) can be present in amounts from about 1 to about 99 parts by weight, and component (b) in amounts from about 99 to about 1 parts by weight.

As regards component (c), as explained only very small amounts of this material need be employed, and concentrations of from 0.01 to 1.00 percent by weight, per 100 parts of the (a) and (b) combined, will achieve the desired color stabilizing effect. The stabilizer will either be phosphorous acid (Y=H in the above formula), or phenyl phosohonic acid (Y=phenyl) or

OMP a fluorocarbon-substituted derivative of phosphorous acid, e.g., fluorocarbon substituted phosphite ester, or a mixture, as indicated. It is preferred to use the smallest amount necessary to obtain the desired result, since amounts in excess of that may be wasted and the possibility exists of some adverse effects on other properties.

- For those embodiments where flame retardancy is a desired characteristic, conventional additives may be included in conventional amounts. For instance, a sulfonate salt, e.g., potassium benzenesulfonic acid, or an aromatic halogen compound, e.g, tetrabromobisphenol A polymers or oligomers, alone, or with a suitable syner- gist, e.g., antimony oxide, can be used in concentrations of from about 0.05 to about 50.0 parts by weight per 100

_* parts of flammable resin n the composition.

The compositions can also contain effective amounts of other suitable additives, such as dyes, pigments and other colorants, fillers, reinforcing agents, lubricants, and so forth.

Preparation of the compositions and processing with finished, shaped articles may be accomplished using any suitable method. The ingredients may be mixed together, for instance, with use of extruders, dough mixers, Banbury mixers, or other mixing devices. The resulting blend may be formed or molded using compression, injection, sheeting or extrusion techniques, as desired and in accordance with particular requirements.

In one preferred procedure, the ingredients are prepared with a preblend, the preblend is extruded in a single screw extruder at 520 to 570°F. , the extrudate is cut into pieces and injection molded at to 525°F. (barrel) and 120 to 180°F. (mold).

The phosphorous acid or other phosphorus containing compound or material in accordance with this invention may be added as an aqueous solution or disper¬ sion or in the presence of moisture without fear of adversely affecting the color stability or other properties of the composition. Moldings made from the present compositions are more color stable due to the presence of the pre¬ scribed additive and will be more resistant to yellowing as indicated, for instance, by a lower yellowness index number, when processed at elevated temperatures, subjected to contact with metals while being processed, or, in general, exposed to those conditions which are known to normally cause yellowing in the case of the polymers described herein.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The invention is further illustrated by the following examples, which are not intended to be limiting.

EXAMPLE 1 A thermoplastic molding composition was pre¬ pared, containing 50% by weight of bisphenol A poly¬ carbonate, having an intrinsic viscosity of about 0.4 dl./g. in chloroform at 25°C. , 50% by weight of a co- polyester (KODAR A150, Eastman Kodak, prepared from 85 mole % bf terephthalate, 15 mole % of isόphthalate and 1,4-cyclohexane dimethanol) , and 0.07% by weight of ^• phosphorous acid. The phosphorous acid was added by shaking in a paint shaker with a blend of the two poly¬ mers. The resultant mixture was compounded by extrusion through a 3/4 inch Killion single-screw extruder with a length/diameter ratio of 24, vented to the atmosphere, using the following conditions: Screw: Twin-flighted

Set,^cF. 520 525 525 535 510 l,000psi 76 Actual, °F. 515 525 530 525

The extrudate was cooled by running through a water bath prior to pelletizing, then dried for 4 hours at 110°C. The pellets were injection molded into test pieces (dimensions: 2.5 inch x 2.5 inch x. 0.125 inch) using a 3 ounce Newbury molding machine and the following conditions:

Melt Temperature 520-550°F. Set Temperature 525°F Mold Temperature 150°F. Injection Rate Medium-Fast (40-20 sec.) Part Weight 50-80% of Shot Capacity

Yellowness index of the molded pieces was measured in accordance with standard, STM procedure D-1925. The results are shown in the Table below. These include a comparison with a corresponding composition containing 0.07% of diphenyl isodecyl phosphite (state-of-the-art compound) as the color stabilizer.

OMP TABLE 1

Yellowness

Add itive Index Phosphorous Acid 4.4

Diphenyl isodecyl phosphite 22.4

As can be seen, the blend containing phosphorous acid has a vastly lower yellowness index.

EXAMPLES 2-5 Several additional compositions in- accordance with the invention were prepared using the polymeric ingredients and amounts noted below. The color stabil¬ izer was phosphorous acid again, but added as a 70% aqueous solution at 0.1% by weight of the total com¬ position. The procedure was otherwise the same as described in Example 1. The yellowness index of each blend, and that of its corresponding control (the same blend but without phosphorous acid added) are listed in Table 2, below.

OMPI TABLE 2 POLYCARONATE BLENDS STABILIZED WITH PHOSPHOROUS COMPOUNDS

Yellowness Index Example Poly imers _a without H3—PO3 with H3—PO₃

2 Poly(ester-carbonate) : ~^* "~ ~^{* —} b copolyester

50:50 by weight 50.11 4.68

3 Polycarbonate: pol (1,4-butylene tere¬ phthalate) 77:23 by weight 50.76 26.70 c

4 Polysulfone :copoly-

•ester 50 :50 by weiαht 17. 27 9 .35 d

5 Poly(sulfone-carbonate) : b copolyester by weight 46.02 8.9

a = HIPEC, comprised of 93 mole % isophthalate, 7 mole % terephthalate, 75 mole % bisphenol A polyarylate and 25 mole % bisphenol A polycarbonate, b = KODAR A 150 (see Example 1) c - UDEL, Union Carbide Corp., containing some polycarbonate units. d = DAXUS, General Electric Co.

The foregoing data demonstrate the color stabiliz¬ ing effect of phosphorous acid.

OMPI EXAMPLES 6-9 The procedure of Examples 2-5 is repeated except that phenyl phosphonic acid is substituted for, phosphorous acid as the stabilizer. The results are shown in Table 3.

TABLE 3 POLYCARBONATE BLENDS COMBINED WITH PHOSPHORUS COMPOUND

Yellowness Index without with

Ex. Blend stabilizer stabilizer

6 HIPEC/KODAR A150 50.11 11.50

7 Polycarbonate/PBT 50.76 22.52

8 UDEL/KODAR A150 17.27 13.27 q DAXUS/KODAR A150 46.02 14.17

The foregoing data demonstrate the color stab- ilizing effect of phenyl phosphonic acid.

OMPI EXAMPLES 10-13 The procedure is again repeated, but with a fluorocarbon substituted phosphite ester (ZONYL* UR, DuPont de Nemours Co.) as the color stabilizer. The results are shown in Table .4.

TABLE 4 ' POLYCARBONATE BLENDS COMBINED WITH PHOSPHORUS COMPOUND

Yellowness Index

Ex^ Blend without Zonyl with Zonyl

10 HIPEC/KODAR A150 50.11 6. .71

11 Polycarbonate/PBT 50.76 42. .60

12 UDEL/KODAR 17.27 14. .08

13 DAXUS/KODAR A150 46.02 13. .33

The foregoing data demonstrate the color stabilizing effect of a fluorocarbon substituted phos- phite ester.

All of the patents mentioned above are incor¬ porated herein by reference.

Other modifications and variations of the invention are possible and will occur to those skilled in the art in the light of the above disclosure. It is to be understood, therefore, that changes may be made in the particular embodiments shown which are within the scope of the invention defined in the appended claims.

OMPI

Claims

CLAIMS :

1. A thermoplastic composition, comprising

(a) an aromatic polycarbonate, an aromatic poly(ester-carbonate) , an aromatic dihydric phenol sulfone carbonate, or a mixture of any of the foregoing, in combination with

(b) a polyester resin comprising units of an aliphatic diol, an aliphatic ether diol, a cyclo¬ aliphatic diol, or a mixture of such diols and an aromatic or cycloaliphatic diacid; and

(c) a color stabilizing amount of (i) a phosphorus-containing compound of the formula

0

II

HO P OH t

Y

0 (l

(R CH CH ) P — (OH) f 2 2 m n where R = F(CF CH ) , n and m are independently 1 or f 2 2 t 2, and t is an integer from 3 to 8.

2. A composition according to Claim 1, in which component (a) comprises an aromatic polycarbonate and component (b) comprises a poly(alkylene terephtha¬ late) resin. •

3. A composition according to Claim 2, in which (a) comprises poly(bisphenol A carbonate) and (b) comprises poly(l,4-butylehe terephthalate).

4. A composition according to Claim 1, in which component (a) comprises a poly(ester-carbonate) and component (b) comprises a copolyester.

OMPI

5. A composition according to Claim 4, in which the copolyester is derived from isophthalic acid, terephthalic acid and an aliphatic diol.

6. A composition according to Claim 1, in which (a) comprises an aromatic dihydric phenol sulfone and (b) comprises a copolyester.

7. A composition according to Claim 6, in which (a) is a copolymer of sulfone and bisphenol A with phosgene and (b) is derived from isophthalic acid, terephthalic acid and an aliphatic diol.

8. A composition according to Claim 1, in which the aromatic polycarbonate of (a) has recurring structural units of the formula

0

II C

wherein A is a divalent aromatic radical of a dihydric phenol.

9. A composition according to Claim 1, in which the poly(ester-carbonate) of (a) has recurring carbonate groups, recurring carboxylate groups and aromatic carbocyclic groups in the linear polymer chain, with at least some of the carboxylate groups and car- bonate groups being bonded directly to ring carbon atoms of the aromatic carbocyclic groups.

10. A composition according to Claim 1, in which the polyester of (b) has recurring units of the formula 0

wherein n is an integer of from 2 to 4.

"gT

OMPI >

11. A composition according to Claim 1, in which (b) has recurring units of the formula

wherein R is aryl or cycloaliphatic having from 6 to 20 carbon atoms and which is the decarboxylated residue derived from an aromatic dicarboxylic acid.

12. A composition according to Claim 1, in which (b) has repeating units of the formula

13. A composition according to Claim 1, in which (b) is a copolyester having repeating units of the formulae

wherein R is aryl or cycloaliphatic having from 6 to 20 carbon, atoms, the x units comprise from about 10 to about 90 percent by weight, and the y units comprise from about 90 to about 10 percent by weight. 14. A composition according to Claim 13, in which (b) is derived from the reaction of 1,4-cyclό- hexanedimethanol and ethylene glycol with terephthalic acid. •5 15. A composition according to Claim 1, which contains from 0.01 to 1.00 percent by weight of (c , based on 100 parts of (a) and (b) combined.

16. A composition according to Claim 1, which comprises from 1 to 99 parts by weight of (a) and from

10 99 to 1 parts by weight of (b) , based on 100 parts of the two together.

17. A method for imparting color stability to a thermoplastic molding composition comprising

(a) an aromatic polycarbonate, an aromatic 15 poly(ester-carbonate) , an aromatic dihydric phenol sulfone carbonate, or a mixture of any of the foregoing, in combination with

(b) a polyester resin comprising units of an aliphatic diol, an aliphatic ether diol, a cycloali-

20 phatic diol, or a mixture of such diols and an aromatic or cycloaliphatic diacid, said method comprising including in the composition

25 0

II

HO P OH

I

Y where Y is hydrogen or phenyl, or (ii) a phosphorus- containing compound of the formula

30

0

⁽R CH CH )— p— (OH) -- 2 m n

where R - F I CF CF ) , n and m are independently 1 or

35 f 2 2 t 2, and t is an integer from 3 to 8.

18. A method according to Claim 17, in which the color stabilizer, component (c), is added to the composition as an aqueous dispersion or otherwise in the presence of moisture. •5

19. A method according to Claim 17, in which component (a) comprises an aromatic polycarbonate and component (b) comprises a poly(alkylene terephthalate).

20. A composition according to Claim 19,_. in which (a) comprises poly(bisphenol A carbonate) and (b) 0 comprises poly(1,4-butylene terephthalate).

21. A method according to Claim 17, in which component (a) comprises a poly(ester-carbonate) and component (b) comprises a copolyester.

22. A method according to Claim 21, in which 5 (b) is derived from isophthalic acid, terephthalic acid and an aliphatic diol.

23. A method according to Claim 17, in which component (a) comprises an aromatic dihydric phenol sulfone and component (b) comprises a copolyester. 0 24. A method according to Claim 23, in which

(a) is a copolymer of sulfone and bisphenol A with phosgene and (b) is derived from isophthalic acid, terephthalic acid and an aliphatic diol.

25. A method according to Claim 17, in which 5 the aromatic polycarbonate of (a) has recurring struc¬ tural units of the formula

0 II h O-A- 0 — C —. wherein A is a divalent aromatic radical of a dihydric 0 phenol.

OMPI

26. A method according to Claim 17, in which the poly(ester-carbonate) of (a) has recurring carbonate groups, recurring carboxylate groups and aromatic car¬ bocyclic groups in the linear polymer chain, with at least some of the carboxylate groups and carbonate groups being bonded directly to ring carbon atoms of the aromatic carbocyclic groups.

27. A method according to Claim 17, in which the polyester of (b) has recurring units of the formula

wherein n is an integer of from 2 to 4.

28. A method according to Claim 17, in which

(b) has recurring units of the formula

29. A method according to Claim 1, in which (b) has repeating units of the formula

0 CH / CH— o— c

30. A composition according to Claim 17, in which (b) is a copolyester having repeating units of the formulae

wherein R is aryl or cycloaliphatic having from 6 to.20 carbon atoms, the x units ccomprise from about 10 to about 90 percent by weight, and the y units comprise from about -90 to about 10 percent by weight.

31. A method according to Claim 30, in which

(b) is derived from the reaction of 1,4-cyclohexane- dimethanol and ethylene glycol with terephthalic acid.

32. A method according to Claim 17, in whicch

(c) is included in an amount of from 0.001 to 1.00 per¬ cent by weight, based on 100 parts of (a) and (b) combined.

OMPI