Background of the Invention

5

Field of the Invention

The present invention relates to thermoplastic polyester/elastomer grafted blends.

10

Description of the Prior Art

Thermoplastic polyesters such as poly(ethylene terephthalate) (hereinafter PET) and poly(butylene

_ - terephthalate) (hereinafter PBT) are widely used as engineering resins because they have high crystalline melting points. good mechanical properties, good hygrothermal dimensional stability, and good solvent resistance. However, although amorphous PET is quite

₂₀ ductile, PET does become brittle upon crystallization by thermal annealing and/or nucleation due to resulting morphological changes; it is also known that crystalline PET is more brittle than crystalline PBT. and therefore, is not as tough as crystalline PBT.

25

Elastomers have been blended with thermoplastic polyesters in order to improve toughness. For example,

U.S. Patent 3.435.093 teaches a blend of PET and an ionomer type hydrocarbon copolymer. U.S. Patent 4,090.996 teaches a composition of PBT. a block copolymer such as styrene-butadiene, and polyamide. U.S. Patent 4.096,202 teaches a blend of PBT and a core-shell rubber consisting of multiphase acrylic compositions. Although the addition of elastomer to ₅ PBT satisfactorily improves the notched impact of the

PBT, the addition of elastomer alone to PET does not satisfactorily improve the notched impact of the PET.

Even after annealing, an elastomer/PBT blend retains most of the improvement in notched impact. 5

Thus, the need exists in the art for a thermoplastic polyester/elastomer blend having improved impact resistance, tensile elongation, and resistance to embrittlement upon annealing. 0

Carbodiimides or polycarbodiimides have been added to PBT to improve impact strength as taught by U.S. Patent 4.110,302; to polyesters to improve thermal stability as taught by U.S. Patent 3,975.329. to provide polyesters suitable for extrusion and blow molding as taught by Chem. Abs. 85. 178533U (1976), and to increase melt strength as taught by U.S. Patent 4.071,503; to copolyesters to improve hydrolytic stability as taught by Chem Abs. 78. 17364e (1973); and ⁰ to polyphenylene ethers to functionalize them as taught by U.S. Patent 4.689,372. Polycarbodiimides also have been blended with polyether-ester copolymer elastomers and ethylene/carboxylic acid copolymers to increase melt strength as taught by U.S. Patent

25 3.9-63.801 and with maleic anhydride and hydroxy compounds to produce high temperature-resistant compositions as taught by U.S. Patent 4,465,839. According to Chem Abs. 104. 1501701.. a composition containing PBT. acrylate-butylene

30 diacrylate-diallylmaleate-methacryla e copolymer rubber, glass fibers, Mark EP-17, and bis(diisopropylphenyl)carbodiimide has good impact and hydrolysis resistance. These references do not teach

PET compositions containing polycarbodiimides wherein

^J ~ ^J ~~ improved toughness results.

European Patent Application 197789 teaches polyester compositions of PBT. butadiene-styrene-methyl methacrylate copolymer, and poly(4,4 '-diphenylmethane carbodiimide) ; the PBT compositions have good impact resistance. Although the reference teaches that a preferred polyester is PET. the reference does not contain Examples directed to PET compositions.

It would be desirable to have a thermoplastic polyester/elastomer blend having better impact resistance. tensile elongation. and resistance to embrittlement upon annealing.

Summary of the Invention

In one embodiment. the present invention provides a polycarbodiimide functionalized elastomer or rubber. As is commonly done in the art. the terms "rubber" and "elastomer" are used interchangeably throughout this application. This composition comprises the reaction product of (a) an elastomer having reactive groups thereon wherein the reactive groups are selected from the group consisting of carboxylic acids, acid anhydrides. acid amides, alcohols. amines. and the like; and (b) a polycarbodiimide. This reaction product, which is a polycarbodiimide functionalized elastomer, can be used alone as a molding composition or because the resulting reaction product is so reactive, the product is useful in the preparation of further products.

As such, in another embodiment, the present invention provides a composition of polycarbodiimide functionalized elastomer and thermoplastic polyester. The composition has improved impact resistance, tensile elongation. and resistance to embrittlement upon annealing. Thus, the present invention fulfills the need in the art for a thermoplastic polyester/elastomer blend having improved properties.

In another embodiment, the present invention provides a melt-blended composition comprising, based on the total composition: about 30 to 95 parts by weight PET; about 0_1 to 10 parts by weight polycarbodiimide; and about 1 to 70 parts by weight elastomer having reactive groups thereon wherein the reactive groups are selected from the group consisting of carboxylic acids, acid anhydrides, acid amides, alcohols, amines, and the like.

It has been found that a thermoplastic PET/modified elastomer composition having polycarbodiimide as a graft-linking agent has improved impact resistance, tensile elongation, and resistance to embrittlement upon annealing compared to a composition of PET. polycarbodiimide. and unmodified elastomer. Such compositions are useful in any application where enhanced impact resistance and tensile elongation of PET are required. Typical applications include automotive exterior parts including bumpers, fascia, and grill panels, and a variety of tubing and jacketing applications.

Other advantages of the present invention will become apparent from the following description and appended claims.

Detailed Description of the Preferred Embodiments

As mentioned above, the reaction product of the present invention has an elastomer. Generally, the elastomer has a Mooney viscosity of about 10 to 70 ML l+8@ 127°C units. More particularly, the elastomer has a Mooney viscosity of about 15 to 50 units,and preferably, about 25 to 50 units.

The elastomer is defined as having an ASTM D-638 tensile modulus of generally less than about 40,000, more particularly less than about 25,000, and preferably less than about 20,000. It can be a block or graft copolymer. Useful elastomeric polymers can be made from reactive monomers which can be part of the polymer chains or branches, or grafted onto the polymer. Useful elastomeric polymers may be produced by any well-known method including emulsion or solution polymerization. Such elastomeric polymers include homopolymers, such as polybutadiene and polyisoprene. and random or block copolymers, such as butadiene/styrene copolymers, acrylonitrile/butadiene copolymers, isobutylene/butadiene copolymers, ethylene/propylene copolymers, ethylene/propylene/diene copolymers. and et ylene alkyl acrylate copolymers. Useful elastomeric polymers can include aromatic vinyl monomers, olefins, and acrylic acid and methacrylic acid and their derivatives. Some preferred elastomers are butadiene/acrylonitrile copolymers, ethylene/propylene copolymers. ethylene alkyl acrylate copolymers, and styrene/butadiene block copolymers and their hydrogenated derivatives.

The elastomer is modified by copolymerization or post-reaction with modifiers such as unsaturated carboxylic acids and derivatives thereof such as amides and anhydrides, and unsaturated alcohols, and unsaturated amines. Commercially available carboxylated polymers such as carboxylated nitrile rubbers and et ylene-ethyl acrylate-acrylic acid polymer may be employed. The reactive groups may be randomly distributed along the length of the polymer chain or at the ends of the polymer chain. The carboxyl or carboxylate functionality can be supplied by reacting the elastomer with a modifier taken from the class consisting of ot , B-ethylenically unsaturated

monocarboxylic acids such as acrylic and methacrylic acids as well as dicarboxylic acids having from 4 to 8 carbon atoms, or derivatives thereof. Such derivatives include anhydrides of the dicarboxylic acids, or the metal salts of the acids.

Illustrative of such acids and derivatives are maleic acid. maleic anhydride, maleic acid amide, fumaric acid, fumaric acid amide, itaconic acid, itaconiσ anhydride. vinyl benzoic acid, and vinyl phthalic acid. Illustrative unsaturated alcohols include 2-propβn-l-ol. 2-buten-l-ol, 3-buten-l-ol, 3-buten-2-ol. 1-hexen-l-ol, 2-hexen-l-ol, 3-hexen-l-ol, 4-hexen-l-ol. 5-hexen-l-ol. 2-cyclohexene-ol, l-octen-3-ol. 5-decen-l-ol. 9-decen-l-ol, and 9-octadecen-l-ol. Illustrative unsaturated amines include p-aminostyrene and 2-aminopropylacrylamide. Preferred modifiers are acrylic acid, fumaric acid, and maleic anhydride. The modifier can be grafted to the copolymer by any well-known grafting process. The elastomer is modified to provide a greater improvement in composition properties when compared to an unfunctionalized elastomer.

Generally, the elastomer contains based on the weight of the elastomer, about 0.1 to 9 percent, preferably about 0.1 to 4 percent, and more preferably about 0.1 to 2.0 percent by weight of the modifier. Generally, the modified elastomer has a number average molecular weight of from about 2,000 to 100.000; preferably about 2,000 to 65,000; more preferably about 5,000 to 35.000; and most preferably about 5,000 to 20.000. A preferred elastomer is aleated ethylene propylene rubber which is 45% by weight ethylene and 54.6% by weight propylene. The elastomer has a 25 Mooney viscosity and is modified with 0.4% maleic anhydride; the elastomer is available in commercial quantities.

Based on the total reaction product, generally about 90 to 99.5 parts by weight modified elastomer are used. Preferably, about 95 to 99.5 parts, and more preferably, about 97 to 99 parts by weight modified elastomer are used.

As mentioned above, the reaction product of the present invention has a polycarbodiimide. Generally, useful polycarbodiimides have average molecular weights of about 1,000 to 15,000. If the polycarbodiimide is to be blended with a thermoplastic polyester, the polycarbodiimide should be dispersible with the molten thermoplastic polyester. Polycarbodiimides having molecular weights greater than about 15,000 may not be dispersible in the thermoplastic polyester.

Useful polycarbodiimides have the following repeating unit

•ex - N = C = N

wherein

X represents a hydrocarbon radical which may be an aliphatic radical containing from 1 to 20 carbon atoms, a cycloaliphatic radical containing from 5 to 12 carbon atoms, an aromatic radical containing from 6 to 16 carbon atoms, or an aromatic or cycloaliphatic C _ς -C ₁₂ radical containing one or more heteroatoms such as N. 0, or S.

The polycarbodiimides may be formed in any manner known to those skilled in the art. for example, by heating diisocyanate compounds in the presence or absence of solvent. The formation of the polycarbodiimide is accompanied by the evolution of carbon dioxide gas.

Although the polycarbodiimides useful in the present invention may be prepared without the use of a catalyst, much higher temperatures are needed in the absence of a catalyst. For certain polycarbodiimides, the use of such high temperatures may result in the formation of large quantities of side products and discolored products. Thus, the polycarbodiimides may be typically prepared by heating the isocyanates in the presence of a catalyst such as the phosphorus containing catalysts described in U.S. Patent 2,853,473 and Monagle, J.J., "Carbodii ides. III. Conversion of Isocyanates to Carbodiimides, Catalyst Studies." J. Ore. Chem. 27. 3851 (1962).

Particularly useful polycarbodiimides include poly (2,4.6-triisopropyl-l,3-phenylene carbodiimide) ; poly(tolyl carbodiimide): poly(4,4'-diphenylmethane carbodiimide) ; poly(3.3 '-dimethyl-4.4'-biphenylene carbodiimide): poly(p-phenylene carbodiimide); poly(m-phenylene carbodiimide); poly

(3.3*-dimethyl-4,4'-diphenylmethane carbodiimide) ; poly(naphthylene carbodiimide); poly(isophorone carbodiimide); poly(cumene carbodiimide); polyCmesitylene carbodiimide); and mixtures thereof. A preferred polycarbodiimide is poly(2, ,6-triisopropyl-l,3-phenylene carbodiimide) which is commercially available as Stabaxol P-100 from Rhein-Chemie.

Based on the total reaction product, generally about 0.5 to 10 parts by weight polycarbodiimide are used. Preferably, about 0.5 to 5 parts, and more preferably, about l to 3 parts by weight polycarbodiimide are used.

Preferably, the reaction product of modified elastomer and polycarbodiimide is made by melt blending the modified elastomer and polycarbodiimide above the melting temperature of the elastomer. The reaction product is prepared by melt-blending the modified elastomer with polycarbodiimide using conditions which are severe enough for a satisfactory reaction to occur. Typical reaction temperatures range from about 240 to 300°C. The reaction product does not have to be

10 the complete reaction of the modified elastomer and polycarbodiimide; it is only necessary that a sufficient amount of reaction occur between the modified elastomer and polycarbodiimide so that the reactive groups of the polycarbodiimide can react with

15 another component to form a graft-linked blend.

While not wishing to be bound by any theory, it is believed that the polycarbodiimide functionalizes the elastomer by a bond through a double bond of the

²⁰ polycarbodiimide. This bond forms a graft to the modified elastomer.

The reaction product itself is useful in that it can be used as a molding compound or independently kept for later blending with other materials.

For preparing other embodiments of the present invention, any thermoplastic polyester which is terminally-reactive is useful in the present invention. Such terminal reactivity is provided by groups such as carboxyl, anhydride, hydroxyl, amino. epoxy, and the like. Such thermoplastic polyesters may be prepared by known techniques such as by alcoholysis of esters of terephthalic acid with ethylene glycol or ^JJ butanediol and subsequent polymerization or by heating the glycols with the free acids or with halide derivatives thereof.

Generally, the thermoplastic polyesters have an intrinsic viscosity of about 0.3 to 1.0. and preferably 0.5 to 0.9. Intrinsic viscosity is obtained by extrapolation of viscosity values to zero concentration of solutions of poly(ethylene terephthalate) in 60 to 40 weight/weight ratio of phenol and tetrachloroethane. The measurements are normalized to 25°C.

Examples of useful thermoplastic polyesters include poly(ethylene terephthalate); poly(propylene terephthalate); poly(butylene terephthalate); poly(pentylene terephthalate); and poly(cyclohexene terephthalate). Preferred thermoplastic polyesters are poly(ethylene terephthalate) and poly(butylene terephthalate) .The more preferred thermoplastic polyester is poly(ethylene terephthalate). Scrap or recycled thermoplastic polyester resin may also be used.

To make a composition based on the reaction product. the reaction product is preferably melt blended with the thermoplastic polyester. Conventional melt-blending techniques can be used, and advantageously, a closed mixing device such as an extruder is used. Typical extrusion temperatures are above the melting point of the thermoplastic polyester but below the degradation point of the components. For superior mixing, the melt temperature of the final composition should exceed about 245°C. Typical reaction temperatures range from about 250 to 280°C. The polycarbodiimide and modified elastomer can be fed together at the throat and the thermoplastic polyester fed into the system downstream.

Based on the total composition, the composition comprises generally about 5 to 70 parts by weight, preferably about 10 to 40 parts by weight, and more preferably about 10 to 30 parts by weight reaction

product; and generally about 30 to 95 parts by weight, preferably about 60 to 90 parts by weight, and more preferably about 70 to 90 parts by weight thermoplastic polyester.

While not wishing to be bound to any particular theory, it is believed that the reactive groups of the polycarbodiimide react with the terminal groups on the thermoplastic polyester. As such, the polycarbodiimide

10 forms a linkage between the modified elastomer and thermoplastic polyester. As a result, the composition has improved impact resistance, tensile elongation, and resistance to embrittlement upon annealing.

15 In another embodiment, the PET, polycarbodiimide, and modified elastomer are melt blended together. Generally based on the total composition, about 30 to 95 parts by weight thermoplastic polyester, about 0.1 to 10 parts by

20 weight polycarbodiimide, and about 1 to 70 parts by weight modified elastomer are used. Preferably based on the total composition, about 60 to 90 parts by weight thermoplastic polyester, about 0.5 to 5 parts by weight polycarbodiimide, and about 10 to 40 parts by - c- . . weight modified elastomer are used. More preferably based on the total composition, about 70 to 90 parts by weight thermoplastic polyester, about 1 to 3 parts by weight polycarbodiimide, and about 10 to 30 parts by weight modified elastomer are used.

30

The components may be fed into an extruder in a variety of ways. All components may be fed into the throat and extruded with a mixing screw. The polycarbodiimide and the thermoplastic polyester may be 5 fed in at the throat and the modified elastomer fed downstream.

The compositions may also include materials to insure uniform crystallinity after molding. These materials may include nucleating agents and plasticizers. Representative nucleating agents include ethylene based ionomers. Representative plasticizers include lactams such as caprolactam and lauryl lactam, sulfonaiαides such as o.p-toluenesulfonamide and N-ethyl, o.-p-toluenesulfonamide and other plasticizers known in the art.

The compositions of the present invention have improved toughness even after crystallization due to the nucleating agent and/or annealing, and are particularly useful in automotive applications where enhanced impact resistance and tensile elongation are advantageous.

Typical annealing conditions for compositions of the present invention include heating at 70 to 160°C for 1 to 24 hours.

The present invention is more fully illustrated by the following non-limiting Examples.

Melt blended compositions in the following Examples were tested according to the following procedures unless otherwise noted: ASTM D-256 notched Izod at 23°C, 0.1875 inch (0.476 cm) thick samples; ASTM D-790 flexural strength and modulus: ASTM D-638 tensile strength modulus and elongation; D-648 heat deflection temperature (HDT) and the indicated load pounds per square inch (psi).

Polymer blends were extruded on a Leistritz 1.1 inches (28 mm) co-rotating extruder using an intensive mixing screw and an L/D ratio of 40 using conditions in the Example.

All test bars were injection molded on an Arburg All Rounder model number 221E/150 with a 35 ton clamp force. Flex bars for testing flexural properties were 0.1875 inches (0.476 cm) thick and tensile bars were 0.125 inch (0.3175 cm) thick. Izod testing was conducted on the flex bars. Typical molding conditions follow: Zone temperatures 250°C, 255°C, 260°C; mold temperature 95°C, with 600 psi (4.1 MPa) and 400 psi (2.8 MPa) pressures and cycle times of 9, 16, 3 seconds. 0

Carboxyl titrations were performed on the solution of thermoplastic polyester in o-cresol/chloroform (70:30 ratio) with dilute sodium hydroxide in benzyl alcohol. 5

Viscosities were performed on a 0.5% solution of the thermoplastic polyester in phenol/trichloroethane (60:40 ratio) at 25°C.

0 In the Examples, all parts are percent by weight unless otherwise indicated.

Example 1

~, This example illustrates the preparation of a reaction product, and then the addition of PET to the reaction product.

Into a Leistritz co-rotating. twin screw extruder, 25 parts of a mixture of Exxon's EX 1601 maleated ethylene propylene rubber (hereinafter EPR) and Rhein-Chemie's Stabaxol P-100 polycarbodiimide with a molecular weight of 11,000 (97:3 ratio respectively) were fed at the throat and 75 parts PET were fed into Zone 5 (i.e., at a rate of three times the rubber feed rate.) The conditions of the extrusion were as follows: Temperatures (Zones 1-9. die) 200°C, 200°C. 220°C. 230°C. 260°C. 250°C. 240°C, 245°C. 250°C. 245°C;

melt temperature 260°C; 950 psi (6.55 MPa) die pressure; 12-14 amperes generated at 13 pounds per hour. A control (Comparative 1) without the Stabaxol P-100 was run. After cooling, pelletizing. drying, and molding into standard test bars, the physical properties of the blends were as follows:

Comparative 1 Example 1

Room Temp Notched Izod 1.5 (81) 6.1 (329)

(ft. lbs/in) (J/M)

Tensile Modulus (psi) 161,000 180.000

(MPa) (1.110) (1.241)

Tensile Strength (psi) (MPa) 3499 (24) 3760 (26)

Elongation to Break 52 90

This example demonstrates that a PET/polycarbodiimide functionalized rubber blend has improved impact resistance and elongation to break compared to a PET/non-polycarbodiimide functionalized rubber blend.

Example 2

This example also illustrates the preparation of a reaction product, and then the addition of PET to the reaction product.

Into a Leistritz co-rotating. twin-screw extruder. 25 parts of a mixture of Exxon's EX 1601 mEPR and Rhein-Chemie's Stabaxol P-100 polycarbodiimide (97:3 ratio respectively) was fed at the throat and 75 parts PET premixed with 5% sodium Surlyn ionomer (a high molecular weight, ethylene-methacrylic acid copolymer neutralized with sodium) added as a nucleator were fed into Zone 5 at a rate of three times the

rubber feed rate. The conditions of the extrusion were as follows: Temperatures (Zones 1-9, die) 200°C, 200°C. 220°C, 230°C. 260°C. 250°C. 240°C. 245°C. 250°C, 245°C; melt temperature 260°C; 950 psi (6.55 MPa) die pressure; 12-14 amperes generated at 13 pounds per hour. A control (Comparative 2) was run without the Stabaxol P-100. After cooling, pelletizing, drying, and molding into standard test bars, the physical properties of the blends were as follows:

Comparative 2 Example 2

Room Temp Notched Izod 1.5 (81) No break (ft. lbs Iin.) (J/M) (>10 ft. lbs)

Tensile Modulus (psi) (MPa) 190,000 163.000

(1.310) (1.124)

Tensile Strength (psi) (MPa) 4.050 (20) 3.760 (26)

Elongation to Break 52 118

This example also illustrates that a PET/polycarbodiimide functionalized rubber blend has improved impact resistance and elongation to break compared to a PET/non-polycarbodiimide functionalized rubber blend.

Example 3

This example illustrates one possible order for feeding the components into the extruder wherein all components together were fed into an extruder.

An intimate blend of 70 parts PET recycled resin with an intrinsic viscosity of 0.7 and a carboxyl titration of 0.033 meq/gm. 4.7 parts of sodium Surlyn ionomer of the type used in Example 2 added as a

nucleator. 23.3 parts Exxon's EX 1601 mEPR. 1.1 parts Rhein Chemie's Stabaxol P-100 polycarbodiimide and 0.1 part paraffin oil was extruded on a 1.1 inches (28 mm) Leistritz ^' counter rotating, twin-screw extruder using an intensive mixing screw. The conditions of the extrusion were as follows: Temperatures (Zones 1-6, die) 180°C. 200°C» 230°C. 240°C. 250°C; melt temperature 255°C, 15 amperes generated at 200 rpm with 750 psi (5 MPa) die pressure and 10 pounds/hour. After cooling, pelletizing. drying at 120°C for 12 hrs. and molding into standard test bars, the blend showed the following properties compared to a control (Comparative 3) run under the same conditions but without the polycarbodiimide:

Comparative 3 Example 3

PET/EPR (weight ratio) 3:1 3:1

% Polycarbodiimide None 1.1 Additive

RT Notched IZOd 1.0 (54) 18.8 (1.015) (ft.lbs.in) (J/M)

Tensile Modulus (psi) (MPa) 199,000 197.000

(1.372) (1.358)

Tensile Strength (psi) (MPa) 4.242 (29) 4,326 (30)

Tensile Elongation 4.0 70.7 at Break (%)

This example also illustrates that a PET/polycarbodiimide/rubber blend has improved impact resistance and elongation to break compared to a PET/rubber blend without polycarbodiimide.

Example 4

This example illustrates another order for feeding the components into the extruder wherein PET and polycarbodiimide were fed in at the throat and the modified elastomer was fed into the system downstream.

Another dual feed system was set up for the 1.1 inches (28 mm) Leistritz co-rotating, twin screw extruder. In this case, polyester was fed with the carbodiimide down the throat and the elastomer was fed at Zone 5.

An intimate blend of 75 parts PET with an intrinsic viscosity of 0.7, 1.9 parts Rhein-Chemie's Stabaxol P-100 polycarbodiimide, and 0.1 part paraffin oil was fed through the throat and 25 parts Exxon's EX 1601 mEPR into Zone five. The conditions of the extrusion were as follows: Temperatures, Zone 1 260°C, Zones 2-9, die 250°C across; melt temperature 269°C, at 170 rpm, 1300 psi (9 MPa) die pressure, 15 amps at 20 pounds per hour. After cooling, pelletizing, drying, and molding into test bars, the blend showed a room temp notched Izod of 2.9 ft. lb/in (157 J/M) and elongation to break of 45% after annealing at 150°C for 15 hours. Even compared to Comparative 3. the composition retained its toughness better after annealing.

Example 5

This example illustrates the effects of annealing a composition formed by feeding all components together into an extruder.

An intimate mixture of 80 parts PET, 20 parts Exxon's EX 1601 mEPR, 1.4 parts Rhein-Chemie's Stabaxol P-100 polycarbodiimide, and 0.1 part paraffin oil was fed together and extruded on a Leistritz co-rotating, twin screw extruder under the following conditions: Temperatures (Zone 1-9, die) 250°C across; melt temp 265°C at 150 rpm; 1120 psi (8 MPa) die pressure. 16 amps generated at 22 pounds per hour. The blend, after making standard test bars. showed the following

10) physical properties before and after annealing 15 hours at 150°C. A control (Comparative 5) without the Stabaxol P-100 was run.

Before After Comp. 5

15 Annealing Annealing A er Annealing

RT Notched Izod No Break 3.2 0.6 (ft. lbs/in) (J/M) (173) (32)

20

Tensile Modulus

(psi) (MPa) 196.000 251.000 249,000

(1.351) (1.730) (1.717)

25 Tensile Strength

(psi) (MPa) 4,750 6.470 6.180

(33) (45) (43)

Elongation at

30 Break (%) 117 51 4.8

The polycarbodiimide composition after annealing retained its toughness better than the control.

35

Example 6

A master batch of PET (0.7 IV) with 4% AClyn ionomer (from Allied-Signal Inc.) which is a sodium neutralized, low molecular weight ethylene acrylic acid copolymer and used as a nucleator, was prepared by melt blending the mixture in a 3" (7.62 cm) single-screw extruder (Egan) and pelletizing the extrudate. 77 parts of the dried, PET master batch pellets were mixed with 19.5 parts of mEPR, 2 parts of sulfonamide plasticizer (Monsanto's MX 2097), and 1.5 parts of Rhein Chemie's Stabaxol P-100 polycarbodiimide. and the mixture was extruded at 250°C on a 1.1 inches (28 mm) co-rotating. twin-screw extruder at 23 lbs/hr throughput rate. The extrudate was pelletized and dried. The pellets were injection molded at 250°C. into standard ASTM test specimens using a mold temperature of 25°C (Sample A) and 80°C (Sample B).

Sample A Sample B

Tensile Modulus (psi) (MPa) 240.000 250.000

(1.655) (1.724)

Tensile Strength (psi) (MPa) 5.656 5.947

(39) (41)

Elongation at Break 80% 72%

Notched Izod (ft lbs/in) (J/M) 8.8 3.2

(475) (173)

The results indicate that PET/polycarbodiimide/rubber blends have good impact resistance and elongation to break.

Example 7

This example uses a commercially available ethylene-butyl acrylate-maleic anhydride terpolymer (Lotador AX 8040) as a reactive impact modifier for the PET.

76 parts PET master batch pellets containing 4% AClyn ionomer (of the type used in Example 6) as nucleator were mixed with 20.5 parts of Lotador AX 8040. 2 parts of a sulfonamide plasticizer, and 1.5 parts of Rhein Chemie's Stabaxol P-100 polycarbodiimide. The mixture was then extruded on a 1.1 inches (28 mm) co-rotating, twin-screw extruder at 250°C and 28 Ibs/hr throughput rate. The extrudate was cooled, pel-letized. and dried. The pellets were then injection molded at 250°C into standard ASTM test specimens using a mold temperature of 80°C. The specimens tested after annealing overnight at 150°C showed the following properties: Tensile modulus 142,000 psi (979 MPa). Tensile strength = 6.400 psi (44 MPa). Elongation at break = 31%, Notched Izod = 2.9 ft.lbs/in (157 J/M) .

The results indicate that PET/polycarbodiimide/rubber blends have good impact resistance and elongation to break.

Example 8

This example illustrates the use of the impact modified PET composition of this invention in tubing applications.

The blend composition from Example 7 was extruded into 0.25 "(0.635 cm) tubing of several different width thicknesses ranging from 20 mil to 40 mil. The extruder was a 1 1/2" (3.81 cm) NRM machine with 24/1 (L/D) screw with 3:1 compression ratio. The

barrel and die temperatures were maintained at 260°C. At a screw speed of 20-32 rpm. the tubing was extruded at approximately 19 ft/min (5.8 m/min) with draw ratios ranging from 3:1 to 5:1.

The tubing was heated at 180°C for 3 hours to see if any embrittlement which normally occurs with PET due to crystallization (with or without nucleator) occurred. The tubing made from the material of the current invention retained its flexibility even after the heat treatment.

Tubings of impact modified PET can be potentially used in a variety of applications such as fuel lines, optical fiber, encasement, etc.

Example 9

A PBT/polycarbodiimide functionalized rubber blend is prepared by following Example 1.

Comparative Example A

This example illustrates the effect of a multiphase, acrylic impact modifier as in U.S. Pat. 4.096,202 for PET.

A mixture of 80 parts of PET (0.7 IV) and 20 parts of a core-shell. acrylic impact modifier designated as Acryloid KM330 (Rohm and Haas) was extruded on a 1.1 inches (28 mm) co-rotating, twin-screw extruder at 250°C and 20 lbs/hr throughput rate. The extrudate was pelletized and dried. The dried pellets were injection molded into standard ASTM test specimens and tested both dry as molded and after annealing.

As molded: Tensile modulus = ^~ 216,000 psi (1489 MPa), Tensile strength = 5.040 psi (35 MPa). Elongation at break = 11%. Notched Izod = 1.2 ft.lbs/in (65 J/M).

After annealing: Tensile modulus = 236.000 psi (1.627

@ 180°C. 1 hr MPa), Tensile strength = 5,560 psi (38 MPa), Elongation at break =- 3.9%. Notched Izod <1.0 ft.lbs/in (54 J/M). O

After annealing: Tensile modulus = 244,000 psi (1,682 . @ 160°C, 3 hrs MPa). Tensile strength = 5,700 psi (39 MPa), Elongation at break = 8%. Notched Izod _ 1.2 ft.lbs/in (65 J/M) 5

The properties, particularly notched izod and elongation, are inferior to those obtained with the PET/polycarbodiimide/rubber compositions of the present invention. 0

Comparative Example B

This example illustrates the effect of a commercial thermoplastic polyurethane elastomer as 5 impact modifier for PET.

A mixture of 80 parts of PET (0.7 IV). preblended with 4% AClyn ionomer (of the type used in Example 6) as nucleator and 20 parts of a thermoplastic 0 polyurethane elastomer (Dow's Pellethane R-2355-95 AE) was extruded at 250°C on a l" (2.54 cm) single-screw extruder (Killion) and the extrudate was cooled, pelletized, and dried. The blend after injection molding showed the following properties: Notched Izod 5 - 0.6 ft.lbs/in (32 J/M), Tensile modulus = 294.000 psi (2,027 MPa). Tensile strength = 6.800 psi (47 MPa). Elongation at break = <5%.

The properties, particularly notched Izod and elongation, are inferior to those obtained with the PET/polycarbodiimide/rubber compositions of the present invention.

Comparative Example C

This example illustrates the effect of blending a commercial, unmodified EP rubber with PET.

80 parts of PET (0.7 IV. preblended with 4% AClyn ionomer of the type used in Example 6) and 20 parts of Vistalon MD 719 (Exxon) were melt blended and extruded on a 1.1 inches (28 mm) co-rotating, twin-screw extruder 250°C and 20 lbs/hr throughput rate. The pellets after drying were injection molded and tested as usual. The properties were as follows: Flexural modulus = 117.000 psi (807 MPa). Tensile strength = 5.000 psi (34 MPa), Notched Izod = 0.47 ft.lbs/in (25 J/M) .

Note the very low impact strength of the blend compared to the compositions of the present invention.

Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.