WO1997013807A1

WO1997013807A1 - Polyester molding composition with improved flow and improved molded part surface

Info

Publication number: WO1997013807A1
Application number: PCT/US1996/016204
Authority: WO
Inventors: Harold Willis Tuller
Original assignee: Alliedsignal Inc.
Priority date: 1995-10-10
Filing date: 1996-10-10
Publication date: 1997-04-17

Abstract

Polyester molding compositions are produced which exhibit a good balance of properties such as flow into molds, gloss and other surface characteristics of molded parts such that they generally do not require painting prior to use. Such are particularly useful for molded parts for consumer and industrial applications. The composition contains a thermoplastic polyester polymer, a reinforcing component, a plasticizer, and a mixture of nucleating agents. A first nucleating agent is an alkali metal salt of a carboxylic acid in an amount of about 0.15 to about 0.35 percent by weight and a second nucleating agent is a metal salt ionomer at from about 0.35 to about 1.2 percent by weight.

Description

POLYESTER MOLDING COMPOSITION WITH IMPROVED

FLOW AND IMPROVED MOLDED PART SURFACE

This application claims the benefit of U.S. Provisional Application

No. 08/642,719, filed May 3, 1996.

BACKGROUND OF THE INVENTION

The present invention pertains to molding compositions. In particular, the invention relates to polyester molding compositions which exhibit a good balance of properties such as intrinsic viscosity, flow into molds, gloss, tensile strength of molded parts, and other surface characteristics of molded parts such that such parts generally do not require painting prior to use. These parts are particularly useful for molded articles for consumer and industrial applications, such as chairs.

It is known in the art that polyethylene terephthalate (PET) is a common thermoplastic, semicrystalline polyester which finds widespread use in fibers, films and packaging applications. Although PET exhibits excellent mechanical and thermal properties once it is oriented and crystallized, its crystallization rate is too slow for conventional injection molding processes. In order to address this problem, a variety of nucleating agents have been used with PET to promote its crystallization and moldability. Suitable nucleating agents are disclosed in U.S. patents 4,357,268; 4,322,355 and 4,551,485 which are incorporated herein by reference. It is also known that sodium carboxylate salts are efficient nucleators for PET. PET molding compositions employing such sodium carboxylate nucleators are known from U.S. Patents 3,435,093; 3,516,957 and 4,486,564 which are incorporated herein by reference. PET molding compositions containing these nucleators, although exhibiting good mechanical rigidity, are somewhat deficient in impact toughness and ductility.

PET molding compositions using a combination of nucleators is also recognized, however, known combinations of nucleators produce molding compositions, which when used in molded parts, produce parts which have good rigidity and impact toughness, but poor flow into molds and inadequate surface characteristics such as exposed fiberglass. It would be desirable to provide a thermoplastic polyester molding composition which exhibits a combination of good melt flow, and surface aesthetics while retaining good physical properties such as rigidity, impact toughness and fatigue.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a composition comprising: a) a polyester containing polymer; and b) a reinforcing component; and c) a plasticizer; and d) a mixture of nucleating agents comprising from about 0.15 to about 0.35 percent by weight of a first nucleating agent comprising an alkali metal salt of a carboxylic acid; and from about 0.35 to about 1.2 percent by weight of a second nucleating agent comprising a metal salt ionomer.

The invention also provides a method for improving the melt flow of a molding composition or improving the surface gloss of a molded article comprising at least one thermoplastic polyester containing polymer; at least one reinforcing component; at least one plasticizer capable of plasticizing the thermoplastic polyester containing polymer; and a nucleating agent. The method comprising incorporating in the composition a mixture of nucleating agents comprising from about 0.15 to about 0.35 percent by weight of the composition of a first nucleating agent which is an alkali metal salt of a carboxylic acid; and from about 0.35 to about 1.2 percent by weight of the composition of a second nucleating agent which is a metal salt ionomer.

The invention further comprises a process for the production of a composition suitable for molding comprising:

A) reacting at least one thermoplastic polyester containing polymer with a mixture of nucleating agents comprising from about 0.15 to about 0.35 percent by weight of the composition of a first nucleating agent which is an alkali metal salt of a carboxylic acid; and from about 0.35 to about 1.2 percent by weight of the composition of a second nucleating agent which is a metal salt ionomer; then B) blending therewith at least one reinforcing component and at least one plasticizer capable of plasticizing the thermoplastic polyester containing polymer.

In the practice of the present invention, a composition is prepared which is broadly composed of a thermoplastic polyester containing polymer, a reinforcing filler, a plasticizer and a blend of nucleators.

The thermoplastic polyester polymer useful for the present invention includes homopolymers and copolymers formed by condensing a dicarboxylic acid or an ester forming compound thereof, with an aliphatic or aromatic diol or an ester forming compound thereof. Suitable dicarboxylic acids for preparing polyesters according to the invention non-exclusively include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, 1,10-decane dioic acid, 1,12-dodecane dioic acid and the like. Suitable aliphatic diols are glycols non¬ exclusively include ethylene glycol, 1,3-propylene glycol, 1,4-cyclohexane dimethanol, and the like. Suitable aromatic diols include hydroquinone, substituted hydroquinone, bisphenol A, and the like. Other ester forming monomers such as hydroxybenzoic acid and hydroxynaphthoic acid may also be included. The preferred composition of the present invention includes linear, saturated polyesters of aromatic dicarboxylic acids. Preferred polyesters non-exclusively include, polyethylene terephthalate (PET) , polybutylene terephthalate, polyethylene naphthalate (PEN) , poly-1,4-cyclohexane dimethylene terephthalate

(PCHT) , and liquid crystalline polyesters such as aromatic polyesters, including polyhydroxybenzoic- hydroxynaphthoic acid copolymer which is commercially available as Vectra from Hoechst Celanese of Somerville, New Jersey. Included within the definition of thermoplastic polyester containing polymers within the context of the invention are polyester homopolymers, mixtures of different polyesters, copolymers of different polyesters and copolymers of polyesters with other moieties, as are well known to the skilled artisan. Polyethylene terephthalate is the most preferred due its ability to be molded at low molding temperatures. The PET may be newly produced virgin PET or may be recycled from soda bottles, fibers, films, and the like. The thermoplastic polyester containing polymers of this invention have a preferred melting point in the range of from about 200 °C to about 330 °C or more preferably from about 220 °C to about 290 °C and most preferably from about 250° C. to about 275° C. The PET used in this invention has a preferred intrinsic viscosity as measured in a 60:40 mixture of phenol and tetrachloroethane of from about 0.3 to about 1.2 deciliters/gram, with a preferred intrinsic viscosity range of from about 0.4 to 0.7 deciliters/gram. Intrinsic viscosity is obtained by extrapolation of viscosity value to zero concentration of solutions of poly(ethylene terephthalate) in the 60 to 40 weight/volume ratio of phenol and tetrachloroethane. The measurements are normalized to 25° C. The polyethylene terephthalate can contain also minor amounts, up to 10%. of other comonomers such as polyethers, 1,4- cyclohexyldimethyldiol, butylenediol neopentyldiol, diethylene glycol, or glutaric acid. The thermoplastic polyester containing polymer component is preferably present in the overall composition in an amount of from about 30 % to about 90 % by weight of the composition, more preferably from about 35 % to about 75 % and most preferably from about 50 % to about 65 % by weight of the composition.

The composition then contains a reinforcing component such as glass fibers and reinforcing fillers. Glass fibers useful for the present composition include chopped glass fibers up to about 5 mm in length. Reinforcing fillers non¬ exclusively include minerals, metals, metal oxides, siliceous materials and metal salts. Examples non- exclusively include mica, alumina, feldspar, asbestos, talc, calcium carbonates, pigments, carbon black, quartz, novaculite, wollastonite, glass flakes, glass beads, clays, silica, kaolinite, bentonite, garnet, saponite, beidellite, other silicates, and mixtures of any of the foregoing. The filler component is preferably treated with a sizing agent such as an amino or epoxy silane, phenolic novolak, multifunctional epoxy compound such as bisphenol A-diglycidyl ether, or triglydidyl cyanurates which serves as a surface adhesion promoter. The reinforcing component is present in an amount sufficient to increase the heat resistance of the compoβition as compared to a similar composition without the reinforcing component. The reinforcing component is preferably present in an amount of from about 15% to about 55%, preferably from about 25% to about 45 % and more preferably from about 25% to about 35% based on the total weight of the composition. The composition contains a plasticizer component. The plasticizer component may be any composition known to plasticize thermoplastic polyester polymers. Such include the organic esters disclosed in U.S. patents 3,516,957; 4,352,904; 4,486,564; 4,429,067; 4,223,125; 4,435,546 and 4,548,978. The preferred plasticizers are the esters of ethoxylated aromatic alcohols which are disclosed in U.S. patent 5,028,647. All of the foregoing patents are incorporated herein by reference.

The most preferred plasticizer is an ester of an ethoxylated aromatic alcohol wherein the ethoxylated aromatic alcohol has the formula

HO-(RO)n-R¹-(OR)_n-OH

wherein each R is the same or different hydrocarbon radical of from 2 to 4 carbon atoms, and each n can be the sane or a different integer of from 2 to 15. By the "same or different" it is meant that where the symbol R or n appear more than once in the formula it can be the same or different in that formula. R¹ is an aromatic radical, preferably derived from an aromatic dialcohol, most preferably bisphenol A. The ethoxylated alcohol has greater than about 20 carbon atoms and preferably 25 to 50 carbon atoms. The alcohol is esterified with an acid which is a carboxylic acid of from 1 to 25 carbon atoms, preferably 3 to 10 carbon atoms. The acid is preferably an aliphatic acid. The acid has from 1 to 3 carboxyl groups and preferably 1 to 2 carboxyl groups with one carboxyl group most preferred. The ester formed has a molecular weight of from about 500 to about 1500, preferably from about 700 to about 1,200, and more preferably from about 800 to about 1,000.

The preferred ethoxylated aromatic alcohols are derived from aromatic dialcohols having from at least 6 carbon atoms and preferably from 6 to about 15 carbon atoms. The aromatic portion of the aromatic dialcohol can contain substituent groups which do not make the plasticizer ineffective. Such groups include hydrocarbons such as methyl groups, ester groups, halogen containing groups and the like. Preferred aromatic dialcohols, include bisphenol A, resorcinol, dihydroxynapthalene (i.e. 2,6 dihydroxynapthalene), and biphenol, with bisphenol A being most preferred. The ethoxylated bisphenol A has the formula H₃

HO-(RO)_n-Ph-C-Ph-(OR)_n-OH I

CH₃

Ph represents a phenylene ring, R is -CH₂CH2- ^{and n} is from 3 to 5, and more preferably, n is 5. The carboxylic acid has from about 1 to about 25 and preferably from about 3 to about 10 carbon atoms and preferably from about 1 to about 3, and most preferably one carboxyl group. The most preferred carboxylic acid is an aliphatic carboxylic acid with from about 3 to about 10 carbon atoms and 1 carboxyl group. Useful acids include, but are not limited to, acetic acid, butyric acid, caproic acid, caprylic acid, pelargonic acid, 2- ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, rieinolic acid, 2-ethyl butyric acid, tall oil acids, fatty acids, and the like. The most preferred acid is 2- ethylhβxanoic acid. Di- and tri-carboxylic acids which are useful include adipic acid, azelyic acid, citric acid, fumaric acid, maleic acid, glutaric acid, succinic acid, tartaric acid, and sebacic acid. The above list of acids is illustrative rather than limiting.

A preferred ester of the present composition is di¬ ll 2-ethylhexoate of an ethoxylated Bisphenol A having the formula:

5

^CH3-^(CH2⁾3 (CH2)₃-CH₃

and has a molecular weight of 876. This 15 plasticizer is commercially available as Plasthall 7070 from CP. Hall Company of Chicago, Illinois. The plasticizer component is preferably present in an amount of from about 1 % to about 5 % by weight of the composition. A more preferred range is from 20 about 2.5 % to about 3.5 % by weight of the composition.

The composition then contains a mixture of nucleating agents. A first nucleating agent is an 25 alkali metal salt of a carboxylic acid. A second nucleating agent is a metal salt ionomer.

The first nucleating agent is an alkali metal salt of a carboxylic acid. The preferred alkali metals 30 are sodium and potassium with sodium being most preferred. The carboxylic acids may have from about 14 to about 22 carbon atoms and preferably from about 16 to about 20 carbon atoms, and most preferably 18 carbon atoms.

The preferred Group I metal salt is a sodium compound. The salts are preferably prepared by reacting an organic carboxylic acid with a Group I metal base to form a Group I metal salt. Suitable carboxylic acid containing compounds include such aromatic acids as benzoic acid and substituted benzoic acid, aliphatic acids such as pivalic acid, fatty acids such as stearic acid, palmitic acid, and dimer acids. The most preferred first nucleating agent is sodium stearate. The first nucleating agent is present in the overall composition in an amount sufficient to increase the crystallization of the polyester compared to a similar composition without the nucleating agent. It is preferably present in an amount of from about .15 % to about .35 %, more preferably from about .28 % to about .35 % and most preferably from about .30 % to about .32 % by weight of the composition.

The second nucleating agent is a metal salt ionomer, preferably an alkali metal salt ionomer. The preferred alkali metals are sodium and potassium, with sodium being most preferred. The «„„„,„

PC17US96/16204

ionomers are low molecular weight alpha olefin containing compounds, such as polyethylene, which have an acid moiety. In the preferred embodiment the ionomers are salts which are the reaction product of a metal base and a low molecular weight copolymer of an alpha-olefin and an acid. The ionomers are formed from organic polymers which are copolymerized with a minor proportion of an acid to provide a copolymer having an acidic moiety. These are then neutralized with a metal or quaternary ammonium base to incorporate metal or ammonium ions into the polymer. The«ionomers themselves are known in the art. Organic polymers useful for this invention non-exclusively include homopolymers and copolymers of alpha-olefins, preferably C₂-Cg olefins, more preferably polyethylene and polypropylene and most preferably polyethylene. The copolymers include an acid moiety which in the preferred embodiment is a carboxylic acid, preferably an unsaturated carboxylic acid. Useful carboxylic acids include monocarboxylic and polycarboxylic acids and derivatives thereof, including esters and anhydrides which are capable of reacting with the bases recited. Useful carboxylic acids or derivatives thereof include unsaturated monocarboxylic acid containing from 3 to 6 carbon atoms and dicarboxylic acids containing from 4 to 8 carbon atoms. Examples of acids copolymerizable with the organic polymer include acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, sulfonic acids and phosphonic acids. Also useful are acid halides, amides and esters including acrylyl chloride and acrylamide. Esters which can be used include methyl acrylate, methyl methacrylate, ethyl acrylate and dimethylaminoethyl methacrylate. Also useful are monoesters of dicarboxylic acids, such as methyl hydrogen maleate, methyl hydrogen fumarate, ethyl hydrogen fumarate, and maleic anhydride. Particularly preferred compounds include alpha,beta- ethylenically unsaturated acids and derivatives thereof. A preferred copolymer acid is a copolymer of ethylene and an alpha,beta-ethylenically unsaturated monocarboxylic acid having 3 to 6 carbon atoms. A most preferred alpha,beta- ethylenically unsaturated monocarboxylic acid is acrylic acid. The most preferred copolymer is ethylene-acrylic acid copolymer. In general the copolymer has an acid number in the range from about 1 to about 250, with an acid number from about 40 to 160 being preferred, and an acid number from about 40 to 120 being most preferred. The acid number is determined by the number of milligrams of potassium hydroxide needed to neutralize one gram of polymer. In accordance with the invention, the organic polymer portion desirably is of low molecular weight and has a number average molecular weight of from about 500 to about 6,000, and preferably from about 1,000 to about 3,500. It constitutes at least about 50, preferably from about 50 to about 99.5, more preferably, about 65 to about 99.2, and most preferably from about 80 to about 98 mol percent of the copolymer. The balance is the acid moiety. The formed copolymers are also of low molecular weight and have a number average molecular weight of from about 500 to about 6,000, and preferably from about 1,000 to about 3,500. Multifunctional polymers with two or moles of acid per polymer molecule are of particular use. The copolymers desirably have a Brookfield viscosity of from about 2 to about 20 grams/cm-sec (200 to about 2,000 centipoises) at 140 °C. , preferably from about 5 to about 10 grams/cm-sec. (500 to about 1,000 centipoises) at 140 °C. Preferred are copolymers of ethylene and acrylic or methacrylic acid containing from about 1% to about 20% by weight acrylic acid or methacrylic acid in the copolymer, preferably about 3.5% to about 12%, and further characterized by a number average molecular weight of from about 1500 to about 3500, an acid number of from about 10 to about 200, preferably about 20 to about 130, and hardness (0.1 mm penetration) of from about 0.5 to about 30, preferably from about 1 to about 10 when tested at room temperature, about 25 °C, according to ASTM D-5 using a needle with a load of 100 grams for 5 seconds. The low molecular weight copolymer acids include the copolymers of ethylene disclosed in U.S. Patent 3,658,741 which is incorporated by reference. The most preferred copolymer is a 15% acrylic acid/85% ethylene copolymer. Useful copolymer acids are commercially available from AlliedSignal Inc. as AC^R540; AC^R580, AC^R5120, AC^R5180 and AC^R5200.

The copolymer is then neutralized by a suitable metal or ammonium base which can be reacted directly with the copolymer by addition. The base is preferably added in the form of an aqueous slurry and/or solution to enhance dispersion in the copolymer. The neutralization reaction is preferably conducted at a temperature above the melt temperature of the copolymer reaction product. The reaction is preferably conducted at about 1 atmosphere. The reaction can be conducted continuously or in batches. The reaction is conducted until a desired degree of neutralization is attained. Bases having valences of 1 to 3 can be used to neutralize the copolymer acid. Preferably, the bases have metallic cations derived from a group of metals which can be chosen from Groups I, II, III and the transition elements for use in this process. Metal cations which are preferred are sodium, potassium, magnesium, calcium, barium, zinc and aluminum cations, with sodium, zinc, calcium and magnesium cations being most preferred. Suitable bases can be metal salts including oxides, hydroxides, acetates, methoxides, oxylates, nitrates, carbonates and bicarbonates. Preferred metallic salt containing materials include calcium oxide, calcium hydroxide, calcium acetate, magnesium oxide and zinc acetate.

The copolymer acid can be neutralized up to 100 percent. It is preferred to neutralize the copolymer reaction product to from 1 to 100 percent, more preferably from 25 to 100 percent. Most preferably 40 to 100 percent of the total acid groups in the reaction product are neutralized with the base .

Reaction additives to help facilitate the reaction can also be added. A particularly preferred additive is an acid such as acetic acid, preferably glacial acetic acid which iβ added to help speed the reaction and make a more uniform ionomer. Other acids include organic acids such as formic acid and propionic acid as well as inorganic or mineral acids such as HCl and H₂S0₄. The organic or inorganic acid, when it is used is present in an amount sufficient to protonate the base. Suitable amounts of the additive range from about 0.1 to 1.0, preferably from about .2% to about .5% based on the weight of the copolymer. The acid converts the base, such as the metal oxides, or hydroxides to more soluble forms. This helps to speed the reaction and reduce agglomerates of the metal compound. It has been found that the addition of water significantly assists in driving the reaction. In the preferred embodiment, water is added to the blend in an amount of from about 0.1% to about 50%, preferably from about 0.1% to about 25% and most preferably from about 0.1% to about 10% based on the total reaction rnase. In a most preferred embodiment an aqueous slurry of the „ „_T„_Λ ,

PCT/US96/16204

cation containing compound is combined with the reaction additive, i.e., acetic acid, and this slurry added to a reactor containing molten polymer. The preferred method of preparing the ionomer of the invention comprises heating the copolymer to above the melting point of the copolymer, preferably from about 100 °C. to about 250 °C. , more preferably about 125 °C. to about 250 °C, and most preferably about 140 °C. to about 175 °C. A sufficient amount of at least one metal or quaternary ammonium containing base is added to neutralize the acid moiety of the copolymer as soon as the polymer or polymer mixture is molten, preferably at a rate that prevents surface accumulation of the base or slurry. An ionomer is formed by the reaction of residual acid groups on the acid containing copolymer with a cation from the base. The preferred ionomer for this invention is an ethylene-acrylic acid copolymer sodium salt. Ionomers useful for this invention include those disclosed in U.S. patents 4,381,376; 4,603,172 and 4,412,040 which are incorporated herein by reference. The most preferred ionomers are low molecular weight sodium ionomers of ethylene copolymers having a carboxylic acid moiety, including low molecular weight carboxyl containing homopolymers and copolymers of ethylene such as ethylene-acrylic acid, ethylene-methacrylie acid and ethylene-fumaric acid. Preferably, the ionomers formed from this invention have a number average molecular weight that ranges from about

1,000 to about 100,000, preferably from about 500 to about 10,000. In the more preferred, the ionomers have a molecular weight of about 500 to about 5,000 and most preferably from about 1,000 to about 2,000. However, the molecular weight can be several orders of magnitude higher where polymer networks are formed by neutralizing multifunctional polymers. The ionomers have a viscosity at 190° C of from about 500 to about 50,000 grams/cm-sec (about 50,000 to about 5,000,000 centipoise), preferably from about 750 to about 20,000 grams/cm- sec, (about 75,000 to about 2,000,000 centipoise) and most preferably from about 1,000 to about 10,000 gramβ/cm-sec. (about 100,000 to about 1,000,000 centipoise).

The second nucleating agent component is present in the overall composition in an amount sufficient to increase the crystallization rate of the polyester compared to a similar composition without the second nucleating agent. It is preferably present in an amount of from about 0.35 % to about 1.2 %, more preferably from about 0.6 % to about 1.0 % The most preferred component is λclyn 285 available commercially from AlliedSignal Inc., of Morristown, New Jersey. In the preferred embodiment, each of the nucleating agents are sodium salts and have a sodium content of at least about .045 percent by weight of total sodium and preferably from about .045 to about .080 percent by weight of sodium.

The composition may also optionally include other additives known to those skilled in the art such as lubricants, plasticizers, flame retardants, processing aids, impact modifiers, pigments, heat stabilizers, uv stabilizerβ, antioxidants in minor amounts effective for their indicated purposes. A minor amount means lesβ than about 50% by weight of the composition. The amounts at which these optional components may be used can be readily determined by those skilled in the art. One preferred processing aid is dioctyl adipate which may be present in an amount of from about 0.06 to about 0.12 weight percent based on the weight of the overall composition. Suitable antioxidants include Irganox 1010, a hindered phenol, Irgaphos 168, a phosphite, and B225, a mixture of Irganox 1010 and Irgaphos 168, all of which are commercially available from Ciba Geigy. The antioxidant may be present in an amount of from about 0.25 to about 0.7 weight percent based on the weight of the overall composition. One suitable stabilizer is diglycidyl ether bisphenol A having a molecular weight of 2,000, which may be present in an amount of from about 0.5 to about 0.8 weight percent based on the weight of the overall composition. A suitable impact modifier is ethylene methyl acrylate which may be present in an amount of from about 1.9 to about 2.5 weight percent based on the weight of the overall composition.

The components of the present invention are preferably combined by melt blending in an extruder by methods well known in the art. In thermoforming applications, the present compositions may be used along with continuous glass fiber reinforcements which may be of the woven or non-woven types. The compositions of the present invention are useful for manufacturing shaped articles, such as structural parts, by such processes as injection molding, gas-assist injection molding, blow molding, extrusion thermoforming and the like. The compositions are evaluated for acceptability according to several criteria. Molded parts made from the composition must have good mechanical properties and appearance and the composition must have good melt flow characteristics. A test molded part should test at least about 600 cycles under fatigue testing according to ASTM D671. It should test at least about 14 foot pounds under no-notch Izod impact testing according to ASTM D4812.

Intrinsic viscosity should be at least about .49 dl/g according to ASTM,D4603, and tensile strength should be at least about 20,000 psi according to ASTM D638. Useful articles should have a surface appearance which is smooth, glossy and without any protruding filler such as fiberglass. For the purpose of this invention, spiral flow is a measure of melted composition viscosity which simulates injection molding. A spiral cavity mold having a 1/4^N x 3/16" cross section and a length of 65 inches is calibrated in inches from 0 to 65 inches along its length. A molten test composition iβ formed at a 580°F melt temperature with a 235°F mold temperature. The molten teβt compoβition iβ pressed through the spiral mold at 600 psi and the number of inches travelled in the mold is measured. A spiral flow of at least about 35 inches is desirable.

The following non-limiting examples serve to illustrate the invention.

A blend of the following components was fed into the throat of a 2.5 inch single screw extruder equipped with a 3 stage, 2 mixer screw and compounded at 520°F at a throughput rate of 180 lbs./hour. The extrudate was pelletized and dried. The compounded pellets were dried and injection molded into test parts on a 150 ton Cincinnati molder and tested for spiral flow. Mold profile temperature was 550-580 °F. In the following table, formulations C and D are according to the invention and formulations A, B, and E are comparative.

COMPONENTS fwt%ϊ A B

Polyethylene 59.72 60.15 61.75 62.17 62.42 terephthalate

PPG 3540 1/8^H 30.50 30.50 30.50 30.50 30.50 chopped strand glass

Plasthall 7070 2.90 2.90 2.90 2.90 2.90 Plasticizer

Diglycidyl ether 0.60 0.60 0.60 0.60 0.60 of bisphenol A Irganox 1010 0.15 0.15 0.15 0.15 0.15

Carbon Black cone. 1.20 1.20 1.20 1.20 1.20

Dioctyl adipate 0.08 0.08 0.08 0.08 0.08

Ethylene methyl 2.20 2.20 2.20 2.20 2.20 acrylate sodium stearate 0.15 0.22 0.31 0.35 0.45

Aclyn 285 2.50 2.00 0.80 0.35 0.00

RESULTS Spiral Flow 28 30 39.5 46 51

Intrinsic viscosity .51 .515 .505 .49 .47 (dl/g)* Tensile Strength 22.IK 22.4K 22.5K 22.OK 22.IK

No Notch 18.0 17.7 17.6 16.0 13.7

Izod Impact Ash 31.2 31.0 31.4 32.0 31.5

* 1.4 weight percent solution in 60:40 mixture of phenol and tetrachloroethane § 25°C.

From theβe results it is determined that formulations A, B, C and D have good intrinsic viscosity, i.e. values of .49 dl/g or above and comparable tensile strength and impact strength. A target spiral flow of at least about 35" is considered acceptable. This is attained by formulation C, D and E. Formulations A and B have spiral flow rates which are too low. Formulation E has a spiral flow rate which is acceptable however, it is considered unsatisfactory for passing rigorous impact and flexural fatigue testing of large molded parts.

EXAMPLE. 2 The following formulations were compounded in a fashion similar to Example 1.

COMPONENTS twt* . JL

Polyethylene 57.02 58.07 terephthalate

PPG 3540 1/8" 30.50 30.50 chopped strand glass

Plasthall 7070 2.90 2.90 Plasticizer

Diglycidyl ether 1.15 1.00 of bisphenol A

B-225 antioxidant 0.30 0.30

Gray concentrate 4.75 3.85

Dioctyl adipate 0.08 0.08

Ethylene methyl 2.20 2.20 acrylate sodium stearate 0.30 0.30

Aclyn 285 0.80 0.80

RESULTS

Melt Index (280°C) 16.2 29.8

2160 g weight

10 minutes

Spiral Flow 39 38 (580°F)

Flex Strength 32,000 32,400

Flex Modulus 1.28 1.3

Fatigue (cycles) 601 787 7000 Stress

Ash 30.3 29.8

Intrinsic .51 .52 Viβcoβity (Molded Part) (dl/g)*

Appearance Excellent Excelle (Molded Part) * 1.4 weight percent solution in 60:40 mixture of phenol and tetrachloroethane § 25°C.

From these results it is determined that both formulations have good intrinsic viscosity, spiral flow, excellent appearance and good mechanical properties.

EXAMPLE 3

The following formulations were compounded in a fashion similar to Example 1. The compounded pellets were injection molded into large chair shells as test parts at a mold temperature » 560- 580 °F. The molded test parts produced from the inventive compoβition had excellent flow propertieβ and βurface quality. The βurface did not requiring painting to be useful.

COMPONENTS fwt.%1 INVENTION COMPARATTVF.

Polyethylene terephthalate 57.82 60.65

Fiberglass 30.00 30.00

Plasthall 7070. Plasticizer 2.90 2.90

Dioctyl adipate 0.08 0.08

Irganox 1010 0.00 0.15

B225 antioxidant 0.30 0.00

Diglycidyl ether bisphenol A 0.85 0.60

Ethylene methyl acrylate 2.20 2.20

Sodium stearate 0.30 0.22

Aclyn 285 0.80 2.00

Black Color cone. 0.00 1.20

Gray Color cone. 4.75 0.00

SESJZ is. Spiral Flow 40" 30"

Intrinsic Viscosity .51 .51 (molded part)

These reβultβ βhow the inventive compoβition haβ good spiral flow while the comparative composition does not.

Claims

What is claimed is:

1. A composition comprising: a) a polyester containing polymer; and b) a reinforcing component; and c) a plasticizer; and d) a mixture of nucleating agents comprising from about 0.15 to about 0.35 percent by weight of a first nucleating agent comprising an alkali metal salt of a carboxylic acid; and from about 0.6 to about 1.2 percent by weight of a second nucleating agent comprising a metal salt ionomer.

2. The composition of claim 1 wherein the polyester containing polymer component comprises polyethylene terephthalate.

3. The composition of claim 1 wherein the polyester containing polymer component has a melting point in the range of from about 200 °C to about 330 °C and an intrinsic viscosity as measured in a 60:40 mixture of phenol and tetrachloroethane at about 25 °C of from about 0.3 to about 1.2 deciliters/gram.

4. The composition of claim 1 wherein the reinforcing component comprises one or more components selected from the group consisting of mica, alumina, feldspar, asbestos, talc, calcium carbonates, pigments, carbon black, quartz, novaculite, wollastonite, glass flakes, glass beads, clays, silica, kaolinite, bentonite, garnet, saponite, beidellite, silicates.

5. The composition of claim 1 wherein the reinforcing component comprises one or more components selected from the group consisting of glass fibers and mica.

6. The composition of claim 1 wherein the plasticizer is an ester of an ethoxylated aromatic alcohol having the formula

HO-(RO)_n-R¹-(OR)_n-OH wherein each R is independently a hydrocarbon radicals of from 2 to 4 carbon atoms, each n is independently an integer of from 2 to 15, and R- is an aromatic radical.

7. The composition of claim 1 wherein the plasticizer has the formula

CH₃

I

HO-(RO)_n-Ph-C-Ph-(OR)_n-OH

I CH3

Ph is a phenylene ring, R is -CH2CH2-, and n is from about 3 to about 5.

8. The composition of claim 1 wherein the plasticizer has the formula CH₃ CH₃

I I CH CH₂

O CH₃ O

CH3-(CH2)3-CH-C-0-(CH2CH₂O)5-Ph-C-Ph-(OCH2CH2)5-0-C-CH-(CH2)3-CH₃.

CH₃

9. The composition of claim 1 wherein the first nucleating agent comprises sodium stearate.

10. The composition of claim 1 wherein the second nucleating agent ionomers are salts of the reaction product of a metal base and a copolymer of an alpha-olefin and an acid.

11. The composition of claim 1 wherein the second nucleating agent ionomers are sodium salts of a copolymer of an ethylene containing polymer and an unsaturated carboxylic acid.

12. The composition of claim 1 wherein the second nucleating agent ionomer is an ethylene-acrylic acid copolymer sodium salt.

13. A method for improving the melt flow of a molding composition comprising a polyester containing polymer; a reinforcing component; a plasticizer; and a nucleating agent, the method comprising incorporating in the composition a mixmre of nucleating agents comprising from about 0.15 to about 0.35 percent by weight of a first nucleating agent comprising an alkali metal salt of a carboxylic acid; and from about 0.35 to about 1.2 percent by weight of a second nucleating agent comprising a metal salt ionomer.

14. A method of improving the surface gloss of a molded article which comprises forming a molding composition comprising a polyester containing polymer; a reinforcing component; a plasticizer; and a nucleating agent, the method comprising incorporating a mixmre of nucleating agents in the composition before molding, the mixmre comprising from about 0.15 to about 0.35 percent by weight of a first nucleating agent comprising an alkali metal salt of a carboxylic acid; and from about 0.35 to about 1.2 percent by weight of a second nucleating agent comprising a metal salt ionomer.

15. A process for the production of a composition suitable for molding which comprises

A) reacting a polyester containing polymer with a mixture of nucleating agents comprising from about 0.15 to about 0.35 percent by weight of a first nucleating agent comprising an alkali metal salt of a carboxylic acid; and from about 0.35 to about 1.2 percent by weight of a second nucleating agent comprising a metal salt ionomer; then B) blending therewith a reinforcing component and a plasticizer.