POLYESTER COMPOSITION

Abstract: Improved injection moldability of polyethylene tereph­ thalates is achieved by the addition of an epoxidized plasticizer and a nucleating agent cooperative with the epoxidized plasticizer to achieve the improved moldability even when the composition is injection molded using mold temperatures of at least as low as 93°C.

Description: POLYESTER COMPOSITION This invention relates to thermoplastic polyester compositions which are especially useful for Injection molding operations conducted at relativEly low mold temperatures. It has long been known that polyethylene terephthalate (PET) has superior physical properties, e.g., resistance to chemical attack, and desirable mechanical and electrical properties. Despite these superior physical properties, PET is not always the material of choice for injection molding usage because relatively high mold temperatures, e.g., 1200-14O0C., must be utilized to insure good moldability. Any attempt to use a lower mold temperature, e.g., 100 C. or lower, results in the injected material being unmoldable as, for one thing, tbe molded article sticks in the mold and often can only be removed with great difficulty. To circumvent this processing disadvantage, the molder is forced to select more expensive materials such as polybutylene terephthalate (PBT), inasmuch as this poly(alkylene terephthalate) is easily moldable even when using mold temperatures as low as 60 C. By being able to use a lower mold temperature for PBT, the time necessary for cooling the injection molded article to a temperature at which it can be removed from the mold is considerably shorter than the cooling ti.me necessary before the PET article can be removed from an initially hooter mold. Since this shorter cool-down period of PBT results in a shorter process cs 'e time and a higher rate of article production, economic justification exists for its use despite its higher unit cost. A welcome contribution to the art would be a PET composition which can be injection molded at relatively low mold temperatures (e.g., 100 C. and below) to yield articles exhibiting good moldability characteristics, e.g., good mold releasability and desirable physical properties. In accordance with this invention there is provided a thermoplastic injection moldable composition which comprises an intimate admixture of: (a) a polyethylene terepbthalate; and (b) an epoxidized plasticizer; and (c)j an adjuvant cooperative with the epoxidized plasticizer of (b) to improve the releasability from the mold1 of articles injection molded from the composition at mold temperatures of at least as low as 930C. Because of this cooperation between the components (b) and (c) above, the compositions may be molded at relatively low mold temperatures (e.g., about 50 C. to about 1000C.) without excessive sticking being encountered. It will be understood, of course, that if desired the composition of this invention may be injected molded at even higher mold temperatures (e.g., about 100 to about 1500C.). A further aspect of this invention is that the composition may additionally contain reinforcing amounts of a reinforcing filler, e.g., glass fibers either alone or in combination with particulate mineral fillers. Other additives may also be used in the composition such as flame retardants, impact modifiers, and the like. The polyethylene terephthalate used herein is preferably homopolymeric PET although crystallizable PET copolymers may also be used. Exemplary of useful PET copolymers are those copolymers in which the copolymer contains at least 80 mol percent of repeating units derived from terephthalic acid and ethylene glycol with the remainder (20 mol percent or less) being derived from other well known acid and/or glycol components. Representative acid components are phthalic acid, isophthalic acid, naphthalene 1,4- or 2,6-dicarboxylic acid, dipbenyl-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxy- lic acid, adipic acid, sebacic acid as well as their halo- genated (preferatly brominated) ccunterparts. The glycol components may be diethylene glycol, neopentyl glycol, cyclohexanedi- methanol, 2,2-bis (4-hydroxyphenyl) propane, 1,3-propanediol, 1,4-butanediol, dibromoneopentyl glycol, the bis(2-hydroxyethvl) ether of tetrabromobis- phenol A, tetrabromo- p-xylylene glycol and the like. The polyethylene terephthalates used herein can be virgin PET or reclaimed PET. Also the PET used in the compositions o' this invention should be injection moldable and thus generally can have an intrinsic viscosity (I.V.) as low as 0.3 and preferably between about 0.4 and 1.2, more preferably between about 0.5 and 1.0, as measured at 250C. in a solvent consisting of 60 percent by weight phenol and 40 percent by weight of tetrachloroethane. For most injection molding applications polyethylene terephthalates in which the I.V. is in the range of 0.4 to 0.9 are most preferred. The compositions of this invention preferably have an amount of the herein described epoxidized plasticizer (also sometimes referred to in the art as an "epoxy plasticizer") within the range of from about 0.5 to about 12 parts per hundred parts of PET (i.e., from about 0.5 to about 12 phr) and an amount of adjuvant within the range of from about 0.05 to about 5 parts per hundred parts of PET, (i.e., fron about 0.05 to about 5 phr). Most preferably, the amounts used for the two components of the composition fal' within the range of from about 2 to about S parts of epoxidized plasticizer and from about 0.1 to about 3 parts of adjuvant per hundred parts of PET. The epoxidized plasticizer described herein should have an oxirane oxygen content of about 0.5% to about 19.0Z by weight. Preferably, the oxirane oxygen content is in the range of from about 3.0% to about 10.0%. The epoxidized plasticizers may be prepared by techniques well known in the art by epoxidation, esterification and ester interchange. Typical techniques used in epoxidation, esterification and ester interchange reactions may be found for example in the chapters on "spoxidation", "Esterification" and "Ester Interchange" in Kirk-Othmer, Encyclopedia of Chemical Technology (second ed. 1965), vol. 8, pp. 238 et seq, pp. 313 et seq, and pp. 356 et seq, respectively. The "epoxy plasticizers" used pursuant to this invention represent epo::y oils and esters of the type used as plasticizer stabilizers for poly(vinyl chloride) resins. While any type cf epoxy plasticizer may @@@ employed in the practice of the invention preferred types include the following: (a) a hydrocarbyl ester of a mono eponidized alkenoic acid, said ester being characterized by containing from about 12 to about 50 carbon atoms (prefe-ably from about 16 to about 36 carbon atoms) in the molecule; (b) an epoxidized unsaturated triglyceride containing at least one epoxide group; and c) an epoxy ester mixture comprising at least one monoepoxy aliphatic monocarboxylic acid ester and at least one epoxy aliphatic monocarboxylic acid ester in which each of the epoxy esters contains from about 7 to about 50 carbon atoms in the molecule. Of the epoxy plasticizers of category (a) above, those having from about 16 to about 36 carbon atoms in the molecule are preferred for use in the compositions of tb.is invention. The alkenoic acids fro which the cPtegory (a) epoxidized esters (f this invention are derived are those having from about 7 to 36 carbon atoms and having the general formula: EMI7.1 wherein R1 is hydrogen or an alkyl radical, R2 is an alI:ylenc radical, and n is either 0 or Exemplary of such mono unsaturated acids are dtc-9-enoic acid, dodec-9-enoic acid, palmitoleic acid, oleic acid, petroselenic acid, vaccenic acid, gadoleic acid, 5-eicosenic acid, 5-docosenic acid, cetoleic acid, erucic acid, nervonic acid, 4-heptenoic acid, 3-methyl-7-octenoic acid, 4-methyl-3-hexenoic acid, 5-methyl-4-hexenoic acid, w-ethyl-3--pcntenoir acid, and 2-octenoic acid. Preferably, the alkenoic acid will have from about 14 to about 24 carbon atoms. Most preferred are the alkenoic acids, e.g., oleic acid, in which the single double bond is internally located, i.e., the double bond is at a non-terminal carbon atom. The epoxidized alkenoic esters of category (a) may be alkyl, aryl;wzalkyl, or cycloalkyi esters or mixtures thereof, with alkyl esters, in which the alkyl group has from about 7 to about 36 carbon atoms being preferred. The most highly preferred alkyl esters are those in which the alkyl group contains from about 7 to about 12 carbon atoms. For example, the alkyl ester can be one in which the alkyl radical forming the alkyl group is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, octyl, decyl, dodecyl, 4-methyloctyl, 2-butyl-2-methylhexyl, eicosyl and the like. A most useful es@en c@ this invention is @@e in which the alkyl group ceatains 8 carbon atome, e.g., octyl mone epoxidised morebasic alkencic acid. Exemplary of the aryl esters are those in which the aryl radical is: phenyl; lower alkyl substituted phenyls, e.g., tolyl (o-, m- or p-isomers), ethylphe yl (o-, m- or p-isomers); dimethylphenyl (various isomers such a@ 2,4-; 2,5-; 3,4- etc, is@@e@s); na@o or substituted phenyl, e.g., chloro@@@@@ @@@ @@omophenyl; naphthyl; and Zäkyl or nalog n substituted naphthyl such as 2-methyl-5-ethylnaphthyl, 2-propvl-4-methyl6-chloronaphthyl, and 7-chlcronaphthyl. Production of the esters of this invention can be effected by esterification of the select alkenoic acid followed by epoxidation of the resultant ester. Epoxidized octyl oleate (which iF also referred to as octyl epoxy stearate) having a 3.6% ty weight minimum oxirane oxygen content can be purchased under the designation DRAPEX 3.2 from Argus Cnemi@al Corporation. Brooklyn, New York 11231. The epoxidized unsaturated triglycerides of category (b) above are triglyce@ides of aliphatic monocarboxylic acid(s) in which each of the acid constituents usually contain from about 6 up to about 30 carbon atoms and in which at least one acid constituent is epoxidized. t will be understood tat an acid constituent may have i:nre tian one epox.de group and that more than one acid constituent may be epoxidized. Examples of aliphatic monocarboxylic acids which may be present in the triglyceride ester include, but are not limited to, the follows: c'eic acid, linoleic acid, linolenic acid, stearic acid, palmitic acid, myristic acid, lauric acid, eleostearic acid, licane acid, ricinoleic acid, palmitoleic acid., petroselenic acid, vaccenic acid, eru@ic acid arachicic acid, tetracosanoic acid, cupric acid, caproic acid and the like. It will be understood of course that prior to epoxidetion at least one of the acid group will contain olefinic unsaturation serving as the site(s) of epoxidation. The epoxidized unsaturated triglycerides of category (b) may be individual compounds or mixtures thereof. The mixtures of epoxidized unsaturated triglycerides should have an oxirane oxygen content falling in the range of about 0.5% to about 12.0 by weight. Preferably, tile oxirane oxygen content is in the range of from about 3.0% to about 10.0. Most preferably, the oxirane oxygen content is from about 7.0 to about 9.5%. The foregoing oxirane oxygen contents also apply to the individual compounds of category (b) when they are used as individual compounds rather than as Examples of unsaturated triglycerides of category (b) which may be expoxidized include, but are not limited to, the following: linseed oil, soybean oil, sunflower seed oil, safflower oil, hempseed oil, tung oil, oiticica oil, corn oil, sesame oil, cottonseed oil, castor oil, olive oil, peanut cil, rapeseed oil, coconut oil, babassu oil, palm oil end the like. Compounding and processing conditions make it preierable to use eponidized unsaturated triglycerides which are relatively non-volatile and easy to mix and to select those which have a molecular weight wbich is sufficiently high to provide these characteristics, for example, a molecular weight of about at least 400. Economic considerations make it convenient to use epoxidized unsaturated triglycerides with a molecular weight of about 400 to about 1000. however, it is deened feasible to use higher molecular eight epoxidized unsaturated triglycerides - ., those having molecular weights greater than 1000. Epoidized unsaturated triglycerides obtained by epoxidation of vegetable fat and oils are especially preferred. Most preferred are epoxidized soybean oil anci epoxidized linseed oil. Fpoxidized unsaturated triglycerides of category (b) can be maoe by techniques weil known to those having ordinary skill in the art. Such suitable compounds may be made by epoxidizing unsaturated triglycerides Including, but not limited to, linseed oil and soybean oil. The epoxidized compounds may be produced by introducing the epoxide linkage by treating the olefinic bond with an epoxidizing agent, such as a peracid, e.g., peracetic acid. by well k-o:-'n technicues. Epoxidized soybean oil having a 7.0% by weight minimum oxirane oxygen content can be purchased under the designation DRAPEX 6.8 and epoxidized linseed oil having a 9.3% by weight minimum oxirane oxygen content can be purchased under the designation DRAPEX 10.4 from Argus Chemical Corporation, Brooklyn, New ork 11231. Epoxy ester mixtures of category (c) above comprising at least one monoepoxy aliphatic monocarboxylic acid ester and at least one diepoxy aliphatic monocarboxylic acid ester in which each of the epoxy esters contains from about 7 to about 50 carbon atoms in the molecule represent still another type of epoxidized plasticizer used pursuant to this invention. By techniques well known in the art these epoxy ester mixtures can be derived from at least one alcohol having from one to about 20 carbon atoms and fro at least two different aliphatic monocarboxylic acids having from about 6 to about 30 carbon atoms or from at least two different alcohols having fro one to about 20 carbon atoms and from at least one aliphatic monocarboxylic acid having from about 6 to about 30 carbon atoms such that the epoxy ester mixture comprises at least one monoepoxy aliphatic monocarboxylic acid ester and at least one do epoxy aliphatic monocarboxylic acid ester in which each of the epoxy esters contains from about 7 to about 50 carbon atoms in the molecule The epoxy ester mixture of category (c) can also be derived from vegetable fats or vegetable oils, the fatty acid fraction of tall oil and other aliphatic monocarboxylic acid esters (by ester interchange with one or more alcohols containing from one to about 20 carbon atoms). It is also deemed feasible to derive the epoxy ester mixture from nonfractionated tall oil- i.e., tall oil that contains its resin acid (rosin or rosin acid) and fatty acid fractions. The alcohols of the category (c) epoxy ester mixtures have from one to about 20 carbon atoms and can be aliphatic, cyclic and aromatic. Exemplary of such alcohols are alkyl, alkenyl, aryl, cycloalkyl, aralkyl alcohols, and the like. Examples include, but are not limited to, the following: methanol, ethanol, propanol, butanol, pentanol, bexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecancl, 2-properie-l-o) (allyl alcohol), 2-buten-l-ol (crotyl alcohol), l-penten-3-ol, trans- 2-hexen-l-ol, 9-decen-l-ol, 10-undecen-1-ol ( -undecylenyl alcohol), cis-9-octadecen-l-ol (oleyl alcohol), cyclobutanol, cyclopentanol, cyclohexanol, cyclobeptanol, cyclooctanol, cyclododeca@ol, cyclopropylmethylcarbinol, cyclopropylmethanol, cyclopentylpropanol, l-cyclopentylethanol, cyclopentyl- methanol, 4-cyclobexyl-l-butanol (cyclohexylbutanol), cyclohexylmethanol, cyclooctylmethanol, cycloundecylmethanol, phenol, naphthol, anthranol, benzyl alcohol, methyiphenyl- carbinol, dimethylphenylethylcarbinol (benzyl-tert- butanol) and the like. The aliphatic monocarboxylic acids of the category (c) ester mixtures have from about 6 to about 30 carbon atoms. Examples include, but are not limited to, the following: oleic acid, linoleic acid, linolenic acid, stearic acid, palmitic acid, myristic acid, lauric acid, eleostearic acid, licanic acid, ricinoleic acid, palmitoleic acid, petroselenic acid, vaccenic acid, erucic acid, arachidic acid, tetracosanoic acid, capric acid, caproic acid and the like. It will be understood of course rhat there will be sufficient olefinic unsaturation either in the alcohol pcrtion or the acid portion so that epoxidation yields the monoepoxy and diepoxy compound. cottalned in the epoxy ester mixture of category (c). Thus, for example, it is possible to repare the following epoxy esters and to mix them to produce epoxy esther mixtures containing at least one monoepoxy aliphatic monocarboxylic acid ester and at least one diepoxy aliphatic monocarboxylic acid ester: : epoxidized octyl oleate, epoxidized octyl linoleate, epoxidized octyl linolenate, epoxidized octyl eleostearate, epoxidized octyl licanate, epoxidized octyl ricinoleate, epoxidized octyl palLitoleate, epoxidized octyl petroselenate, epoxidized octyl vaccenate, epoxidized octyl erucate, as well as the epoxidized methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, allyl, crotyl, oleyl, cyclobutyl, cyclooctyl, naphthyl, anthryl or benzyl esters thereof and the like; and glycidyl stearate, glycidyl palmitate, glycidyl myristate, glycidyl laurate, glycidyl arachidate, glycidyl tetracosanate, glycidyl caprate, glycicyl caproate, as well as the epoxidized crotyl and oleyl esters thereof and the like. Examples of vegetable fats and vegetable cils from which the epoxy ester mixture of category (c) may be derived include, but are not limited two, t following: coconut oil, babassu oil, palm oil, castor oil, olive oil, peanut oil, rapeseed oil, corn oil, sesame oil, cottonseed oil, soybean (il, runflower secd oil, safflower oil, hempseed oi, linseed oil, tung oil, oiticica oil and the like. Thus, for example, it is possible to prepare the methyl, ethyl, propyl, butyl, pentyl, benzyl, heptyl, octyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, allyl, crotyl, oleyl, cyclobutyl, cycl ooctyl, naphthyl, snthryi or benzyl epoxy esters of coconut oil, babassu oil, Dalm oil, castor oil, olive oil, pe@nut oil, rapeseed oil, corn oil, sesame oil, cottonseed oil, soybean oil, sunflower seed oil, safflower oil, hempseed oil, linseed oil, tung oil, or oiticica oil and the like. Mixtures comprising monoepoxy aliphatic monocarboxylic acid esters arid epoxy aliphatic monocarboxylic acid esters (category (c) above) are available commercially. For example, epoxidized esters of soybean oil and linseed oil are available from Viking Chemical Company, 838 Baker Building, Minneapolis, Minnesota 55402, under the product designa ti@@ VIKOFLEX. Such epoxidized esters are: methyl epoxy soyate (VIKOFLEX 7010), ethyl epoxy soyate (VIKOFLEX 7020), propyl epoxy soyate (VIKOFLEX 7030), butyl epoxy soyate (VIKOFLEX 7040), lexyl epoxy soyate (VIKOFLEX 7060), octyl epoxy scyate (VIKOFLEX 7080), methyl epoxy linseedate (VIKOFLEX 9010), ethyl epoxy linseedate (VIKOFLEX 9020), propyl epoxy linseedate (VIKOFLEX 9030), butyl epoxy linseedate (VIKOFLEX 9040), hexyl epoxy linseedate (VIKOFLEX 9060) and octyl epoxy linseedate (VIKOFLEX 9080). An epoxy ester mixture of the fatty acid fraction of tall oil having a 5.0% by weight minimum oxirane oxygen content is commercally available from Argus Chemical Corporation, 633 Court Street, Brooklyn, N. Y. 11231 under the product designation DRAPEX 4.4, which is octyl epoxy tallate. To date, tests with certain epoxidized plasticizers and a cooperative adjuvant in the compositions of this Invention demonstrate that the adjuvant is synergistic. Thus, without the use of a synergistic adjuvant in conjunction with any of the above described hydrocarbyl esters of mono epoxidized alkenoic acids (category (a) above) there is no observed significant enhancement of PET moldability. Further, the use of the epoxidized unsaturated triglyceride (category (b) above), such as epoxidized soybean oil c. epoxidized linseed oil, in combination with a synergistic adjuvant. such as sodium stearate, gives a significart enhancement of PET moldability. Likewise, tne use of an cf there hareinefter de @cribed synergistic adjuvants without these epoxidized plasticizers i is thout observable effect. In view of the ineffectiveness of these epoxidized plasticizers and adjuvants when used alone, it is surprising that their use in combination gives the very neticeable moldability enhancement. Use of a cooperative adjuvant in conjunction with the above described epoxy estei mixture (category (c) above) gives very noticeable moldability enhancement over compositions without the epoxy ester mixture. Synergistic effect is rooted for example hy the use, as the adjuvant, of alkali metal salts of substantially saturated aliphatic monocarboxylic acids, such as sodium acetate, potassium acetate, sodium propionate, potassium propionate, sodium hexanoate, sodium octanoate, sodium decanoate, sodium laurate, potassium laurate, sodium tetradecanoate, sodium hexadecanoate, sodium stearate, and the like; and of alkali metal salts of unsaturated aliphatic monocarboxylic acids, such a± sodium acrylate, potassium methacrylate, and the like. Also commercially av@ilable soaps, such as IVORY SOAP and IVORY SNOW (which are manufactured by The Procter and Gamble Company of Cincinnati, Ohio, and IVORY SNOW is believed to comp-ise about 85% by weight sodium oils of tallow facty acids and about 15% by weight sodium salts of coconut fatty acids and IVORY SOAP is believed to comprise about 50% by weight sodium salts of tallow fatty acids and about 50% by weight sodium salts of coconut fatty acids) are useful as synergistic adjuvants. The lithium, cesium and rubidium salts while not as available and econo-ical, should provide the synergistic effect sought. Of the foregoing salts, sodium stearate Is most preferred. Other effective synergistic adjuvants include sodium carbonate, talc, mica, boron nitride, SURLYN 1605 (an ionomer resin containing sodiu. ions and manufactured by E. I. du Pont de Nemours and Company), p-hydroxybenzoic acid, sodiuir benzoate and zinc stearate. Without desiring to be bond by theoretical considerations, it is believed that naterials which, pursuant to this invention, serve as adjuvants tend to be substances which are also effective nucleating agents. In accordance with this theory, it is contemplated that other substances which will prove to be effective adjuvants for use in this invention include metal salts of carboxylic acid such as zinc, lead, calclus, barium and cupric laurates and stearates, and potassium benzoate; metal salts of inorganic acids such as silver nittate and stannous chletide; highly @olat organic compounds such as m-hydroxybenzoic acid, tetrachlorophthalic anhydride, inositol and phthalimide; sodium and potassium salts oi organic polymers containing pendant carboxyl groups such as copolymers of olefins and actylic or methactylic acids and copolymers of aromatic olefins and maleic anhydride; and the like. Note in this conncetion french 2,129,162; British 2,015,013; and The British Polvmer Journal, Volume 11, pages 146-150 (September 1979). To date tests performed using the epoxy ester mixtures of category (c) have not been extensive enough to prove that the cooperation exerted between the epoxy ester mixtures and the adjuvants is synergistic (i.e., all of the necessary baselines have not ben run). However, inasmuch as synergistic coopeiation was found tc exist between many other combinations of this invention, it is contemplated and indeed expected that the combinations of the epoxy ester mixtures and the adjuvants will prove synergistic in actual practice. To insure even dispercion of the epoxidized plasticizer and the adjuvant in the PET, it is preferred that the adjuvant and the epoxid zed plasticizer, when it exists as a solid, be of a particle CiLe so thtt at least 30% will pass through a 100 mesh U. S. Standard Sieve. Highly preferred epoxidized plasticizer-adjuvant combinations are: the ester-adjuvant combinatfon of epoxidized octyl oleate and sodium stearate; the epoxidized unsaturated triglyceride-adjuvant combinations of epoxidized soybean oil and sodium stearate and epoidized linseed oil and sodium stearate; and the Epoxy ester mixture-adjuvant combinations of the epoxy esters of soybean oil, of linseed oil or of the fatty acid fraction of tall oil and sodium stearate, combina- tions of octyl epoxy soyate (e.g., VIKOFLEX 7080), octyl epoxy linseedate (e.g., XrIKOFLEX 9080) or octyl epoxy tallate (e.g., DRAPEX 4.4) and sodium stearate are more preferred. To improve the injection moldability of polyethylene terephthalates any standard commercial grade or any heat stable grade of sodium stearate is utilizable in the compositions of this invention provided that the sodium stearate utilized is of a particle size so that at least 30% will pass through a 100 mesh, U. S. Standard Sieve. For example, such sodium stearate cen be purchased as "Sodium Stearate or or "Sodium Stearate, Heat-Stable" from Witco Chemical Corporation, Organic Divisiet. New Work, New York 10017. As mentioned previously, other additives may also be utilized in the composition of this invention For example, it is most useful it the composition additionally conteins a reinforcing filler This filler, depending on its nature, an increase the strength and impact qualities of the PET composition. In fact, he us of a reinforcing riller is often required by most present day commercial usage of injection molded PET. In general, any reinforcement can be used, e.g., fibers, whiskers, or platelets of metals, e.g., aluminum, iron or nickel, and the like, and non-metals, e.g., ceramics, carbon filaments, silicates, asbestos, titanate whiskers, quartz, glass flakes and fibers, and the like. Although it iv only necessary to have at least a reinforcing amount of the reinforcing filler present, in general, the filler will comprise from about 10 to about 160 parts per hundred of the unreinforced polyethylene terephthalate resin. Amounts of filler, especially glass fibers, in the range of from about 30 to about 140 parts per hundred of the unreinforced PET are preferred as such compositions have particularly desirable properties. From the standpoint of ease of injection molding usage, reinforced compositions of this invention, especisll, those using glass fibers, preferably contain a filler constituent in an amount within the range of from about 30 te about 90 parts per hundred parts by eight of the un@einforced polyethylene terephthate resin. Of the various fillers that may be used in the compositions of this invention the preferred reinforcing filler are glass. It is most preferred to use fibrous glass filaments cf lime-aluminum borosilicate glass that are relatively soda free. Th--s is known 9 "E" glass. The length of the glass filaments and whether they are bundled into fibers and the fibers bundled in turn to roving, etc., is not critical to this invention. However, it has been found convenient to use glass strands of at least about 1/8 inch in length. It is to be understood that during compounding considerable fragmentation of the strands will occur and that even further reduction of length occurs in the final injection molded article. Other additives may also be utilized in the composition of this invention to achieve certain desirable characteristics in the final injection molded product. For example, flame retardants, impact modifers, antioxidants, ultraviolet ray absorbents, lubricants, antistatic agents, colorizing agents (e.g., zinc sul fide), antifungal agents, foaming agents, etc., depending upon the ultimate use of the arcicle injection molded. .he compositions cf this invention can be pre- pared by blending the various components in a blender, e.g., a tumble blender or a Henschel mixer, compounding the mixture in an e':truder, e.g., a twin-screw 28 m Werner-Pfleiderer extruder, and thereaftal chopping the extrudate into pellets. The resaltant product is suitable for use in injection molding c@erarions. It is noteworthy that the compositions of th3s invention can be satisfactorily injection molded at mold temperatures less than 100 C. with an acceptab@y short cycle time and with the molded article exhibiting physical properties which ate commercially attractive or at least have commercial potential. The present invention is further illustrated in the following examples, which are not to be construed as limiting. EXAMPLES 1-29 The various PET compositions of Examples 1-29 were prepared by mixing the components to form a premix, compounding the premix in a single screw extruder at temperatures of about 500 F. (2600C.), and molding the pellets into an article on a reciprocating screw Injection molding machine. The injection mold was suitably shaped and dimensioned for providing an article having the configuration shown n the Figure -- which 5 is a top plan view of the article. The mold utilized was a center gated mcld having a nonmovable planar sprue side tjd a movable cavity side. As can be seen in the Figure the article formed by the mold bas a plurality of runners, labeled "A", which terminate into various test pieces. Emanating from the center C the runner grid is a conventional tapered spruc. Tre of the test pieces are reciangular bets and are labeled with the letter "B". These "B" bars are about six inches long, 1/2 inch wide and 1/5 inch thick. The test piece labeled "C" in the Figure is a reciangular bar which is 2-1/2 inches long, 1/2 inch wide and 1/8 inch thick. The two "dog bone" shaped test pieces are labeled "D" and are used for the testing of tensile properties. They measure about 6-1/2 inches long, 1/8 inch thick and 3/4 inch in width at each of their ends and 1/2 inch in width at their middles. The test piece labeled "E" is 4 inches long, 2-3/4 inches wide and 1/8 inch thick. The runners ad sprue are approximately 3/8 inch in cross sectional witch. This configuration for the test article was chosen for it complexity and for its yield of test specimens which are used in accordance with well recognized standard tests. The complexity of the article configuration was also thought sufficient to give a good prediction of moldability performance of tithe composition wne used @o form typical commercial articles. The PET, @poxidized plasticizer, glass and sodium stearate used iii the Examples are identified as follows: -- Polyethylene Terephthalate (ET): fro Goodyear Tire and Rubber Company; Vituf 5900 - crystalline PET having an intrinsic viscosity of 0.59 measured at 250C. in solvent consisting of 60 percent by weight phenol and 40 percent by weight of tetrachloroethane; -- Epoxidized Octyl Oleate (Octyl Epoxy Stearate): from Argus Chemical Corp under the designation DRAPEX 3.2; -- Glass Fiber Strands: from Owens-Corning Fiberglas, Corp., designated Owens-Corning Fiberglas 419AA (3/16 inch chopped strands) or PPG Industries, Inc., PPG 3540 Fiberglass (1/8 inch chopped strnds);and -- Sodium Stearate: such as that available from Witco Chemical Company. Tables I, II, and III (Examples 1-8, 9-16 and 17-24, respectively) report the observations noted of the moldability of various compositions of this invention. The observation of compositions not utilizing the combination of @poxidi@@d plasticized and adJuvants of this invention are shown in Table IV (Compatative Examples 25-29. Where moldability is shown as "Excellent", the molded article freely fell from the mold upon mold opening. A rating of "Good" Indicates that a majority of the molded articles fell freely from the cavity side or te mold. When less than a majority but till a substantial number of articles fell freely, a rating of "@air" was given. The "Poor" rating indicates that most of the injection molted articles bad to b p@lled from the cavity side of the mold but that no sticking to the sprue side of the mold was observed or that, even though the main portion of the article did not stick to the sprue side of the mold, the sprue portion of molded article stuck on the sprue side. A rating of "Non-Moldable" indicates that the article stuck to the sprue sid of the mold and that the molding cycle had to be stopped so that te molded article could be removed from the mold by chiseling, prying, etc. In ali the Examples the mold temperature was kept around 200 F. (930C.). Table I Compositions of This Invention and Their Moldability Examples Composition 1 2 3 4 5 6 7 8 PET Remin, parts 100 100 100 100 100 100 100 100 Glass Fiber, phr* 43 43 43 43 43 43 43 43 Octyl Epoxy Stearate, phr* 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Sodium Stearate, phr* 0.5 - - - - - - 0.3 Sodium Carbonate, phr* - 0.5 - - - - - Sodium Acetate, phr* - - 0.5 - - - - Sodium Propionate, phr* - - - 0.5 - - - Sodium Actylate, phr* - - - - 0.5 - - Sodium Methactylate, phr* - - - - - 0.5 - IVORY SNOW#, phr* - - - - - - 0.5 Talc, phr* - - - - - - - 1.0 Moldability Excel- Excel- Excel- Good Fair Poor Excel- Excellent lent lent lent lent @ Parts per 100 parts PET a Believed to be about 85% by weight sodium salts of tallow fatty acids and about 15% by weight sodium salts of coconut fatty acids. Table II Compositions of This Invention and Their Moldability Examples Composition 9 10 11 12 13 14 15 16 PET Resin, parts 100 100 100 100 100 100 100 100 Glass Fiber, phr* 43 43 - - 43 43 43 43 Octyl Epoxy Stearate, phr* 3.0 7.2 3.0 3.0 3.0 3.0 3.0 3.0 Sodium Stearate, phr* 0.5 - 0.5 0.5 - - - Boron Nitride, phr* - - - - 0.5 - - SURLYN 1605, phr* - - - - - 0.5 - p-Hydroxybenzoic Acid, phr* - - - - - - 0.5 Sodium Benzoate, phr* - - - - - - - 0.5 Titanium Dioxide, phr* 1.0 - - 0.3 - - - Talc, phr* - 1.4 - - - - - - Moldability Excel- Excel- Excel- Excel- Excel- Excel- Excel- Excellent lent lent lent lent lent lent lent * Parts per 100 parts PET Table III Compositions of This Invention and Their Moldability Examples Composition 17 18 19 20 21 22 23 24 PET Resin, parts 100 100 100 100 100 100 100 100 Glass Fiber, phr* 43 43 43 43 43 43 43 43 Octyl Epoxy Stearate, phr* 3.0 3.0 3.0 3.0 3.0 3.0 5.7 5.7 Zinc Stearate, phr* 0.5 - - - - - - Sodium Stearate, phr* - 0.5 0.5 0.5 0.5 0.5 0.7 0.7 Zinc Sulfide, phr* - 2.0 2.0 2.0 2.0 - - (Colorant) Titanium Dioxide, phr* - - - - - - - 0.7 (Colorant) Moldability Excel- Excel- Poor** Excel- Excel- Excel- Excel- Excellent lent lent lent lent lent lent * Parts per 100 parts PET ** Variant rating of poor believed to be the tesult of compounding errots. Table IV Compositions Not of This Invention and Their Moldability Comparative Examples Composition 25 26 27 28 29 PET Resin, parts 100 100 100 100 100 Glass Fiber, phr* - - 43 43 43 Octyl Epoxy Stearate, phr* - - - - 3.0 Sodium Stearate, phr* - - - 0.5 TiO2. phr* - 0.3 - - Moldability Non- Non- Non- Non- Non Moldable Moldable Moldable Moldable Moldable * Parts per 100 parts PET As can be seen from Table IV the absence of either the epoxidized plasticizer or the synergistic adjuvant results in a non-moldable composition under the same molding compositions. Comparable results were obtained with compositions corresponding to Example 18-21 except that the PET utilized was American Enka's T-0740. The data shown in Table V illustrate the good balance of physical properties exhibited by articles injection molded from compositions of this invention at mold temperatures of about 200 F. (93 C.). The test specimens were subjected to the following ASTM procedures: Specific Gravity -- D 792-66 (1975); Tensile-Yield, Elongation and Tensile Elastic Modulus -- D 638-77a; Flexural Strength and Flexural Elastic Modulus -- 790-71 (1978); Izod Impact for 1/4-inch bar at 23 C. - D 256-78; Heat Deflection Temperature -- D 648-72 (1978); Vicat Softening Point -- D 1525-76; and Rockwall Hardness -- D 785-65 (2976). Table V Compositions of This Invention and Their Physical Propetties Examples Composition 18 19 20 21 PET Resin (Vituf 5900) - patts 100 100 100 100 Glass Fibet, phr* 43 43 43 43 Octyl Epoxy Stearate, phr* 3 3 3 3 Sodium Stearatye, phr* 0.3 0.0.5 0.7 0.1 Properties Tensile Yield, psi 18.939 14.780 16.070 20.100 Tensile Elastic Modulus, 106 psi 1.30 1.31 1.40 1.24 Elongation, % < 10 < 10 < 10 < 10 Flexutal Strength, psi 30.510 29.840 29,530 31.@00 Flexutal Elestic Moduius, 105 psi 1.37 1.31 1.40 1.36 Izod Impact, 1/4" bar, ft-1b/in. 1.6 1.6 1.5 1.7 Izod Impact, 1/8" bar, ft-1b/in. 1.7 1.8 1.6 1.9 Rockwell Hardness, R Scale 122 122 122 * Parts per 100 parts PET EXAMPLES 30-52 The various PET compositions of Examples 30-52 were prepared as set forth in Examples 1-29. The PET, glass --nd sodium stearrte used in these Examples ar': identified .n Examples 1-29. The epoxidized plasticizers used n Examples 30-52 are identified as follows: -- Epoxidized Soybean Oil: from Argus Chemical Corp. under the designation DRAPEX 6.9, which is an essentially fully epoxidized soybean oil containing 7 weight percent of ox.rane oxygen; and -- Epoxidized Linseed Oil: from Argus Chemical Corp. under the designation DRAPEX 10.4. Tables VI and VI1 (Exemples 30-38 and 39-45, respectively) report the observations noted of the moldability of various compositions of this invention. The observation of compositions not utilizing the combination of epoxidized plasticizer and adjuvants of this invention are shown in Table VIII (Comparative Examples 46-52 of which 51 and 52 correspond to Compara tive Examples 28 and 27 respectively -- see Table IV.) The moldability ratings have the same definitions as those set forth in Examples 1-29. In all of these Examples the mold temperature was kept around 2000F. (930C.). Tably IV Compositions of This Invention and their Moidability Exaqples Composition 30 31 32 33 34 35 36 37 38 PET Resin, Parts 100 100 100 100 100 100 100 100 100 Glass Fiber, phr* 43 43 43 43 43 43 43 43 43 DRAPEX 6.8, phr* 6 6 3 4 5 6 8.6 5 5 Talc, phr* 2 1 1 1 1 1 1.4 - Mich, phr* - - - - - - - - TiO2, phr* - - - - - - - - Moldability Good Excel- Good Good Good Good Fxcei- Fait** Poor lent lent * Parts per 100 parts by weight of PET resin ** Amotphous skin Table VII Compositions of This Invention and Theit Moldability Examples Composition 39 40 41 42 43 44 45 PET Resin, parts 100 100 100 100 100 100 100 Glass Piber, phr* 43 43 43 43 43 43 43 DRAPEX 6.8, phr* 3 3 3 3 4.3 - 3 DRAPEX 10.4, phr* - - - - - 3 Sodium Stearatt, phr* 0.5 0.5 0.5 0.5 0.7 0.5 Sodium Methactylate. phr* - - - - - - 0.5 Moldability Excel- Good Good Good Excel- Excel- Poor lent lent lent * Parts per 100 patts by weight of PET resin Table VIII Compositions Not of This Invehtion and Their Moldability comparative Exemples Composition 46 47 48 49 50 51 52 PET Resin, parts 100 100 100 100 100 100 100 Glass Fibet, phr* 43 43 43 43 43 43 43 DRAPEX 6.8, phr* 6 3.0 8.6 - - - Talc, phr* - - - 2 2.8 - Sodium Steatate, phr* - - - - - 0.5 Moldability Non- Non- Non- Non- Non- Non- Nonmoldable moldable moldable moldable moldable moldable moldable * Parte per 100 parts of PET As cen be seen from Table VITI, the absence of either the ep@xidized plasticizet or the synergistic adjuvant te@ults in a non-moldable @@@@osition under the same molding conditions. The data shown in Table IX illustrate the good balance of physical properties exhibi@ed by arti@ies injection molded from compositicns of this invention at mold temperatures of about 200 F. (93 C.). The test specimens were subjected tc the ASTM proce@u@es set forth in Examples 1-29. Table 1X Compositions of This Invention and Their Physical Properties Examples Composition 36 39 41 42 43 PET Resin, parts 100 100 100 100 100 Glass Fiber, phr* 43 43 43 43 43 Dtapex 6.8, phr* 8.6 3 3 3 4.3 Sodium Stentate, phr* - 0.5 0.5 0.5 0.7 Talc, phr* 1.4 - - - Properties Tensile Yield, psi 15,900 18,800 18,600 18,500 18,800 Tensile Eiastic Modulus, 106 psi 1.38 1.32 1.42 1.38 1.32 Elongation, % - 10.9 8.3 < 10 Flexutal Strength, psi 26,400 32,200 30,000 30,400 32,200 Flexutal Elastic Modulus, 106 psi 1.29 1.44 1.33 1.41 1.44 Izod Impact, 1/4" bar, 1.3 1.6 1.6 1.7 1.6 ft-1b/in. Rockwell Hatdness, R Scale - 119 121 120 * Patts per 100 patts PET EXAMPLES 53-57 The various PET compositionE of Examples 53-57 were prepared as set forth in Examples 1-29. The PET and sodium stearate us in these Examples are identified in Examples 1-29. The enoxidized plasticizers and blast used in Examples 53-57 are identified as follows: -- Octyl Epoxy Soyate: from Viking Chemical Company under the product designation VIKOFLEX 7080; -- OCtY1 Epoxy Linseedate: from Viking Chemical Company under the product designation VIKOFLEX 9080; -- Octyl Epoxy Tallate: f-om Argus Chemical Corp. under the product designation DRAPEX 4.4; and -- Glass Fiber Strands: from Owens-Corning Fiberglas, Corp., designated Owens-Corning Fiberglas 419AA (3/16 inch chopped strands). Table X reports moldability of various compositions of this invention (Examples 53-55) and of compositions not of this invention (Comparative Examples 56 and 57 which correspond to Comparative Examples 28 and 27 respectively -- see Table IV) in terms of observation and "the number of sticks" (i.e., the number of times the molding cycle had to be stopped and a molded specimen physically removed from the mold) in relation to the "number of shots" (i.e., the number of inject-ions) that were made with the given PET composition. In severe cases, removal of a stuck part required prying or chiseling. Whe@e the obs@@vation is shown ns "Ex@@llent", the molded article freely fell from the mold upon mold opening. A @@ting of "Non-Moldable" indicates that the article stuck to the sprue side of the mold and that the moiding @ycle had to be stopped se that the molded article could be temoved from the mold by chiseling, prying etc. In all the Examples the mold temperature was kept around 200 F. (93 C). TABLE X Various PET Compositions and Their Moldability Examples Comparative Examples 53 54 55 56 57 Composition Polyethylene Tetephthalate, parts 100 100 100 100 100 Glass Fiber, phr* 43 43 43 43 43 Octyl Epoxy Linseedaten, phr* 3.0 - - - Octyl Epoxy Soyateb, phr* - 3.0 - - Octyl Epoxy Tallatec, phr* - - 3.0 - Sodium Stearate, phr* 0.5 0.5 0.5 0.5 Zinc Sulfided, phr* - - 2.0 - Moldability Obsetvation Excellent Excellent - Non- Nonmoldable moldable Numbet of Sticks/Number of Shots 0/10** 0/100** 0./15 10/10+ 10/10+ * Parts per 100 parts PET ** Estimate - number of shots were not recorded + Estimate - number of shots were not recorded; however, in each run the molded specimen had to be physically r@moved from the mold a VIKOFLEX 9080 from Viking Chemical Company b VIKOFLEX 7080 from Viking Chemical Company c DRAPEX 4.4 from Argus Chemical Corporation d Zinc Sulfide - colotizing agent As can be seen from Table X, comparative Examples 56 and 57, the absence of the epoxidized plasticizer or the absence of both the epoxidized plasticize and the adjuvant results in a non-moldable composition under the same molding conditions. The data shown in Table XI illustrate the good balance of physical properties exhibited by articles injection molded from compositions of this invention at mold temperatures of about 200 F. (93 C.). The test specimens were subjected to the ASTM procedures set forth in Examples 1-29. TABLE XI Compositions of This Invention and Their Physical Propetties Examples 53 54 55 Composition Polyethylene Tetephthalats, parts 100 100 100 Glass Fibet, phr* 43 43 43 Octyl Epoxy Linseedaten, phr* 3.0 - Octyl Epoxy Soysteb, phr* - 3.0 Octyl Epoxy Tallatec, phr* - - 0.3 Sodium Stearate, phr* 0.5 0.5 0.5 zinc Sulfided, phr* - - 2.0 Properties Specific Gravity 1.583 1.587 1.578 Tensile Yield, psi 19,900 18,600 18,500 Tensile Elastic Modulus, 103 psi 1,330 1,410 1,405 Elongation at yield, % < 10 < 10 Flexutal Strength, psi 32,000 38,500 27,700 Flexutal Elastic Modulus, 103 psi 1,440 1.421 1,360 Izod Impact, 1/4" bar, ft-1bs/in. 1.9 2.0 1.4 Izod Impact, 1/8" bar, ft-1bs/in. 1.7 1.7 # 264 psi, C. 239 241 237 Heat Deflection Temperature # 66 psi, C. 250 249 Rockwell Hatdness, R Scale 123 123 * Parts per 100 parts PET a VIKOFLEX 9080 from Viking Chemical Company b VIKOFLEX 7080 from Viking Chemical Company c DRAPEX 4.4 from Argus Chemical Corporation d Zinc Sulfide - colorizing agent

Claims: CLALMS: 1. A. thermoplastic compoìtion which is injection-moldable at a relatively low mold temperature, said composition comprising an intimate admixture f: (a) a polyethylene terephthalatc; d (b) an epoxidized plasticizer; and (c) a nucleating agent cooperative with the epoxidixed plasticizer of (b) to improve the releasability from the injection mold, of articles injection molded from said composition at mold temprratre es of at least as low as 93 0C. 2. The composition of Claim 1 wherein said epoxidized plasticizer has an oxirane oxygen content within the range of 3.0% to 10.0% by weight. 3. The composition of Claim 1 wherein said epoxidized plasticizer is a hydrocarbyl ester of a mono epoxidized alkenoic acid, said ester being characterized by containing from 12 to 50 carbon atoms in the molecule. 4. The composition of Claim 3 wherein said hydrocarbyl ester is an alkyl ester in which the alkyl radical has from 7 to 36 carbon atoms. 5. The composition of Claim 4 wherein the ester is an octyl ester. 6. The composition of Claim 1 wherein said epoxidized plasticizer is epoxidized octyl oleate. 7. The composition of Claim 1 wherein said epoxidized plasticizer is an epoxidized unsaturated tri glycerin containing at least one epoxidt group. 8. The composit-on of Claim 7 wbereim -a-d epoxidized triglyceride is epoxidized linseed oil. 9. The composition of Claim 7 wherein said epoxidized triglyceride is epoxidized soybean oil. 10. The composition of Claim 1 wherein said epoxidized plasticizer is an epoxy ester mixture con,- prising at least one monoepoxy aliphatic monocarboxxl c acid ester and at least one dicsoxy aliphatic monocarboxylic acid ester in which each of the epoxy esters contains from 7 to 50 carbon atoms in the molecule. 11. The composition of Claim 10 wherein said epoxy ester mixture is derived from at least one alcohol having from one to 20 carbon atoms and from at least two different aliphatic monocarboxylic acids having from 6 to 30 carbon atoms. 12. The composition of Claim 10 wherein said epoxy ester mixture is derived from at least two different alcohols having from one to 20 carbon atoms and from at least one aliphatic monocarboxylic acid having from about 6 to 30 carbon atoms. 13. The composition of Claim 10 wherein said epoxy ester mixture is derived from vegetable oils s or vegetable fats. 14. The composition cf Claim 10 wherein said epoxy ester mixture is derived fro soybean oil or linseed oil. 15. The composition of Claim I wherein said nucleating agent is synergistially cooperative wiLh the epoxidized plasticizer. 16. The composition of Claim 35 wherein said synergistic nucleating agent is a monocarboxylic acid salt. 17. The copositior: oç Claim 15 wherein said synergistic nucleating agent is (a) an alkali metal monocarboxylic acid salt selected from sodium stearate, sodium acetate, sodium propionate, sodium acrylate, or sodium benzoate, (b) an intimate mixture comprising the sodium salts of tallow fatty acids and coconut fatty acids, or (c) sodium carbonate, talc, mica, boron .nitride, Et,-hydroxybenzoic acid, zinc stearate or an ionomer resin containing sodium ions. 18. The composition of Claim 1 wherein said epoxidized plasticizer is present in an amount within the range of from 0.5 to 12 parts per hundred parts of said polyethylene terephthalate and said nucleating agent is present within the range of 0.05 to 5 parts per hundred parts of said polyethylene terephthalate. 19. The composition of Claim 1 wherein said composition additionally contains a reinforcing filler which comprises glass fibers. 20. A thermoplastic composition which is injection-moldable at a relatively low mold temperature, said composition characterized by an intimate admixture of: (a) a polyethylene terephthalate having an intrinsic viscosity of between 0.4 and 0.9, as measured at 250C. in a solvent cons sting of 60* by weight of phenol and 40% by weight of tetracbloroethane; and (b) from 30 to 90 parts by weight of glass fiber reinforcing filler per 100 parts by weight of the polyethylene terephthalate; and (c) an epoxidized plasticizer; and (d) a nucleating agent cooperative with the epoxidized plasticizer of (c) to improve the releasability from the Injection mold, of articles Injection molded from said composition at mold temperatures of at least as low as s3 c . 21. The composition of Claim 20 wherein said epoxidized plasticizer is epo.idized ocryl oleate, epoxidized soybean oil, epoxidized linseed oil, octyl epoxy linseedate, octy epoxy soyete or octyl epoxy tallate and said nucleating agent is 2 sodium salt of a monocarboxylic acid. 22. The composition of Claim 21 wherein said nucleating agent is sodium stearate.

Inventors: CHUNG, JAMES Y.J., HORNBAKER, EDWIN D., JONES, JESSE D., LI, HSUEH M.
Applicants: ETHYL CORPORATION
Application year: 1982
Main classification: C08L67
IPC codes: C08K5