MXPA00004960A - Modification of thermoplastic vulcanizates with a thermoplastic random copolymer of ethylene - Google Patents

Abstract

Random thermoplastic ethylene copolymers can be used to increase the elongation to break and toughness of thermoplastic vulcanizates. Polypropylene is a preferred thermoplastic phase. The rubber can be olefinic rubbers. Random thermoplastic ethylene copolymers are different from Ziegler-Natta ethylene copolymers as the compositional heterogeneity of the copolymer is greater with Ziegler-Natta copolymers. This difference results in substantial differences in properties (elongation to break and toughness) between thermoplastic vulcanizates modified with random thermoplastic ethylene and those modified with Ziegler-Natta ethylene copolymers. An increase in elongation to break results in greater extensibility in the articles made from a thermoplastic vulcanizate.

Description

MODIFICATION OF THERMOPLASTIC VULCANISES WITH A RANDOM THERAPY OF ETHYLENE FIELD OF THE INVENTION The ethylene thermoplastic random copolymers can be used to increase the elongation at break and the toughness of thermoplastic vulcanizates made from a thermoplastic polypropylene phase and a rubber that can be entangled. Ethylene thermoplastic random copolymers can be obtained from various suppliers as single-site catalyst polymers, often named polymerized metallocene catalyst polymers. They differ from other ethylene copolymers in that the comonomer can be uniformly distributed in substantially all polymer chains, although in the prior art thermoplastic ethylene copolymers the comonomer increased disproportionately in a portion of the polymer chains and the comonomer it was disproportionately reduced in a portion of the polymer chains, resulting in a broad composition distribution for the polymer.

BACKGROUND OF THE INVENTION Polypropylene thermoplastic vulcanizates and rubber have gained widespread acceptance as thermo-fix rubber substitutes in a variety of applications. It would be desirable for many of these applications to increase the elongation at break of said thermoplastic vulcanizates and increase the overall toughness (as measured by the area under the tensile strength curve) when a thermoplastic vulcanizate is measured in a stress test. Polyethylene and polyethylene copolymers are very interesting polymers because they can have amorphous regions and crystalline regions. The amorphous regions of the polyethylene are rounded at room temperature with a glass transition temperature well below 0 ° C. The crystalline regions of polyethylene and more rigid materials that have a melting point usually between about 80 ° C and 135 ° C depending on the characteristics of the crystals and the density of the polyethylene. The crystalline regions of polyethylene are denser, that is, they have higher densities than the amorphous regions of the polymer. High density polyethylene has relatively higher proportions of crystalline polymer compared to the amorphous polymer than its low density counterparts. Generally, the branching polymer chain and the incorporation of comonomers decrease the crystallinity of the polyethylene because the crystal structure can not contain many comonomers or large chain branches. The amorphous regions of the semicrystalline polyethylene add tenacity to the material, since it can undergo elastic and plastic deformation to withstand stresses or forces, thus preventing the crystalline regions from fracturing.

Ethylene-propylene-diene (EPDM) polymers also known as ethylene-propylene-diene-polymethylene rubber with ethylene to propylene weight ratios of 25:75 to about 75:25 have a sufficient incorporation of ethylene and propylene in the polymer chain in such a way that these materials are elastic at room temperature instead of solids, such as polyethylene or polypropylene. Polyethylene copolymers have been made in the past with catalysts other than single-site catalysts. Various polymerization techniques have been used in such a way that a specific portion of the comonomer is present in the copolymer. However, few polymerization catalysts or polymerization systems are known that actually randomize ethylene with comonomers in a thermoplastic copolymer. Linear low density polyethylene involves polymerization with a fed ethylene and a second olefin generally fed from 4 to 8 carbon atoms, maintaining a relatively constant feed rate. The catalysts have different different active sites, in such a way that some sites incorporate the second olefin more efficiently than others. The different sites can also result in different lengths for the polymer chains. This results in a broad molecular weight distribution and a broad composition distribution in the resulting polymer. Another method for making low density polyethylene involves the use of polymerization conditions that encourage branching in the polyethylene chain, said branching altering the crystallinity of the polyethylene and causing a reduced crystallinity and consequently a reduced density.

BRIEF DESCRIPTION OF THE INVENTION Polypropylene thermoplastic vulcanizates, a rubber, and a random thermoplastic ethylene copolymer can be prepared by mixing a random thermoplastic copolymer of ethylene with the components of a thermoplastic vulcanizate or by mixing a random thermoplastic copolymer of ethylene with a thermoplastic vulcanized preformed polypropylene and a rubber . Ethylene thermoplastic random copolymers are commercially available as a result of the development of single site catalysts, including metallocene catalysts. Ethylene thermoplastic random copolymers currently have narrow molecular weight distributions and narrow composition distributions. The average concentration of the comonomer is from about 5 to about 30% by weight based on the weight of the ethylene copolymer. As is known in the art, thermoplastic vulcanizates usually comprise from about 15 to about 75 parts of the thermoplastic phase and from about 25 to about 85 parts by weight of the rubber phase. They can also comprise various amounts of healers, plasticizers, fillers, etc. The ethylene thermoplastic random copolymer is desirably present in amounts of about 5 to about 150 parts per 100 parts of polypropylene in the thermoplastic vulcanizer. The rubber may be any hydrocarbon rubber, such as butyl rubber, halobutyl rubber, halogenated (for example brominated) copolymers of paramethylstyrene and isobutylene, EPDM rubber, and natural rubber or homo or diene-based copolymer rubber.

DETAILED DESCRIPTION OF THE INVENTION The random thermoplastic ethylene copolymer used to modify the thermoplastic vulcanizates of the present invention is different from other ethylene copolymers used in the thermoplastic vulcanizates above; it is much more random in terms of incorporation of comonomers in the copolymer; previously, copolymers with more than 2, 5 or 10% by weight of comonomer were rubber or a physical mixture of low copolymers in repeating units of ethylene and other copolymers significantly richer in repeating units of ethylene, whose mixing would have a percentage in relative weight of comonomer and ethylene cited in the literature of the product. The thermoplastic random ethylene copolymer used in the present invention can have very narrow molecular weight distributions (number average molecular weight / number average molecular weight) of about 1.5 or 1.7 to 3.5, most desirably from 1.8 to about 3.0 and preferably about 1.5 or 1.9 to 2.8 due to the single site catalyst, also called metallocene catalyst, currently used to prepare such polymers. The description is not limited to the ethylene thermoplastic random copolymers made with metallocene catalysts, it also uses those commercially available polymers as illustrative of a polymerization method capable of making the random copolymers operable in the present disclosure. In addition, molecular weight distributions are recited as a method to identify such polymers, but they are not a requirement for the polymer to function in a thermoplastic vulcanizate. The ethylene thermoplastic random copolymer may have various amounts of one or more comonomers therein. In the examples, the ethylene thermoplastic random copolymer is often referred to as a plastomer which indicates that it has some properties of both a plastic and an elastomer. Desirably, the amount of repeating units of one or more comonomers is from about 5, 10, 15 or 20 to about 30 or 35% by weight of the ethylene thermoplastic random copolymer. Most desirably, the amount of repeating units of said comonomer (s) is from about 10 to about 25% by weight. The amount of ethylene in said thermoplastic random ethylene copolymer desirably is from about 65 or 70 to about 80, 85, 90 or 95% by weight, and very desirably from about 65, 70 or 75 to about 80, 85, or 90% by weight. The comonomer (s) can be any ethylenically unsaturated compound that can be copolymerized with ethylene using a single-site catalyst. The ethylenically unsaturated comonomer (s) desirably has from about 3 or 4 to about 12 carbon atoms, very desirably from about 3 or 4 to about 8 carbon atoms, and monoolefins with the specific scale of carbon atoms are preferred. carbon. Examples of such comonomers include alkyl acrylates, such as ethylacrylate, butylacrylate; monoolefins such as propylene or octene, etc. Ethylene thermoplastic random copolymers desirably have densities of about 0.85 or 0.86 to about 0.91, 0.92 or 0.93 grams per cubic centimeter, most desirably from about 0.86 or 0.87 to about 0.90, 0.91 or 0.92 grams per cubic centimeter. As the polymerization systems, for example, the single-site catalyst polymerization system including metallocene catalysts, readily incorporate comonomers with ethylene in the ethylene thermoplastic random copolymer, the comonomers are randomly distributed within the individual polymer chains and the individual polymer chains are uniform in the composition of the comonomer. Due to the uniform distribution of the repeating units of the comonomers within the polymer chains and the uniformity of the comonomer distribution within the polymer, contrary to the polyethylene copolymers of the prior art, the ethylene thermoplastic random copolymers tend to present very narrow melting temperature scales by test methods such as dynamic scanning calorimetry (DSC) compared to the prior art ethylene copolymers. This is due to the fact that ethylene thermoplastic random copolymers have a very uniform crystal structure and therefore melt within a very narrow temperature scale. Random ethylene copolymers vary from most other ethylene copolymers in that the melting point in the dynamic scanning calorimetry of the random copolymers decreases when the comonomer content increases. The peak represents the highest amount of endothermic crystal fusion at a single temperature. Therefore, desirably the random ethylene copolymer has a peak melting temperature of less than about 120 ° C, very desirably from about 50 about 120 ° C, even more desirably from about 55, 60 or 65 to about 105 or 110 ° C, and preferably about 55, 60 or 65 at about 90, 95 or 100 ° C. The ethylene copolymers of the prior art have a very wide melting temperature scale because they have a larger scale of copolymer compositions. The ethylene thermoplastic random copolymer can be incorporated into the components that are used to form a thermoplastic vulcanizate (TPV) or mixed with a TPV composition prior to vulcanization of the rubber component, or added after said vulcanization. The physical properties of the resulting mixture may or may not vary depending on whether the ethylene thermoplastic random copolymer was added before or after vulcanization of the rubber phase. The ethylene thermoplastic random copolymer can be considered a complement to the polypropylene of the thermoplastic vulcanizate or can be considered to be substituted on a weight basis for the polypropylene in a thermoplastic vulcanizate. When the random copolymer is added before vulcanization, it is anticipated that a majority of the ethylene thermoplastic random copolymers will be in the thermoplastic thermoplastic phase resulting thermoplastic, although they may be present disproportionately at the interface between the rubber phase and the thermoplastic phase. Because the melting temperature of the crystalline portion of the ethylene thermoplastic random copolymer is lower than that of the semi-crystalline polypropylene, it can easily be melted with the thermoplastic vulcanizate or components thereof at normal processing / mixing temperatures for the thermoplastic vulcanizate. The thermoplastic random ethylene copolymer is desirably present in amounts of about 5 to about 150 parts per 100 parts of propylene in the thermoplastic vulcanizate, most desirably in amounts of about 10 to about 120 parts per 100 parts of polypropylene, very desirably still from about 10 or 25 to about 100 parts per 100 parts by weight of polypropylene, and preferably from about 25 to 80% parts by weight per 100 parts by weight of the polypropylene. In this way, the ethylene thermoplastic random copolymer can be present in amounts of from 0 to about 60% by weight of the thermoplastic phase of the thermoplastic vulcanizate. Since the thermoplastic phase of the thermoplastic vulcanizate can be from about 15 to about 75% of the blend of the thermoplastic and rubber phase (without fillers, oils, etc.), the percentage of the ethylene thermoplastic random copolymer based on the The total weight of the thermoplastic vulcanizate can vary from 1 or 2 to about 40 or 50% by weight based on the combined weight of the thermoplastic polypropylene and the rubber components (without fillers, oils, etc.) or the weight of the thermoplastic vulcanizate. The main portion of polymers in thermoplastic vulcanizate is semicrystalline polypropylene; the ethylene thermoplastic random copolymer and a crosslinkable rubber. Examples of semicrystalline polypropylene are polypropylene, its copolymers and mixtures thereof. The rubber may be a polyolefin like EPDM rubber which, due to the random nature of its repeating structure or side groups, does not tend to crystallize. Examples of rubber include rubber EPDM, butyl rubber, halobutyl rubber, halogenated (for example brominated) copolymer of p-alkylstyrene and an isomonoolefin of about 4 to 7 carbon atoms (for example isobutylene), natural rubber, homo or copolymers of at least one diene monomer or combinations thereof. Minor amounts of other polymers may be added to modify the flow properties, such as fillers or diluents, or additives, such as polymeric antioxidants. Non-polymeric materials such as oils, fillers, diluents and additives (discussed in a later paragraph) may be present in large quantities. The amounts of most of the components to be mixed will be specified either 1) per 100 parts by weight of the semicrystalline polypropylene mixture and the rubber, or 2) per 100 parts by weight of rubber. The semicrystalline polypropylene desirably is from about 6 to about 85% by weight, very desirably from about 7 to about 75, and preferably from about 8 to about 60 weight percent of the thermoplastic vulcanizer, desirably, the rubber it is from about 5 to about 70, very desirably from about 10 to about 50 and preferably from about 15 to 45% by weight vulcanized thermoplastic. Desirably, the other conventional components of TPV, for example fillers, oils, curing agents, processing aids, etc., are close to 0, 1, 2 or 10 about 87, 88 or 89 percent by weight of the TPV, very desirably from about 0, 1, 2 or 15 to about 81, 82 or 83, and preferably from about 0, 1, 2 or 25 about 75, 76 or 79 weight percent. The semicrystalline polypropylene is desirably from about 15 to about 80 parts by weight, very desirably from about 25 to about 75 parts by weight, and preferably from about 75 to about 50 parts by weight per 100 parts of the mixture of semi-crystalline polypropylene and unsaturated rubber. The rubber desirably is from about 20 to about 85 parts in 25, most desirably from about 25 to about 75 parts by weight and preferably about 50 about 75 parts by weight per 100 parts by weight of said mixture. If the amount of the semicrystalline polypropylene is based on the amount of rubber, it is desirably from about 17.5 to about 320 parts by weight, very desirably from about 33 to about 300 parts and preferably from about 33 to about 200 parts. by weight per 100 parts by weight of rubber. The terms "mixture" and "thermoplastic vulcanizate" used herein mean a mixture ranging from small particles of well-dispersed crosslinked rubber in a semicrystalline polypropylene matrix to co-continuous phases of semicrystalline propylene and a partial rubber to fully crosslinked or combinations of the same. The term "thermoplastic vulcanizate" indicates that the rubber phase is at least partly cured (crosslinked). The term "thermoplastic vulcanizate" refers to compositions that may possess the properties of a thermoset elastomer and may be reprocessed in an internal mixer. Upon reaching the temperatures above the softening point or the melting point of the semicrystalline propylene phase, continuous sheets and / or molded articles may form what appears to complete the complete fabric or melt of the thermoplastic vulcanizate under conventional forming or molding conditions for the thermoplastics. Following the dynamic vulcanization (cure) of the rubber phase of the thermoplastic vulcanizate, desirably less than 5 weight percent of the rubber may be extracted from a sample of the thermoplastic vulcanizate in boiling xylene. Techniques for determining the rubber that can be extracted are set forth in the U.S. patent. No. 4,311, 628 and are incorporated herein by reference.

The semicrystalline propylene comprises semicrystalline thermoplastic polymers of the polymerization of monoolefin monomers (for example from 2 to 10 carbon atoms) by a high pressure, low pressure or intermediate pressure process; or by a Ziegler-Natta catalyst, or by metallocene catalysts. It can have any tacticity (eg isotactic and syndiotactic) or it can be a copolymer such as an impact modified propylene copolymer or a random polypropylene copolymer. Desirably, the monoolefin monomers converted to repeating units are at least 80, 85 or 93 percent monoolefins of the formula CH 2 = C (CH 3) -H. The polypropylene can be a homopolymer as well as a reactor copolymer. Desirably it has a peak melting temperature of at least 120 ° C. The rubber can be any rubber that can react and cross-link under cross-linking conditions. These rubbers may include natural rubber, EPDM rubber, butyl rubber, halobutyl rubber, halogenated (for example brominated) copolymers of p-alkylstyrene and an isomonoolefin, homo or copolymers from at least one conjugated diene, or combinations thereof. EPDM, butyl and halobutyl rubber are referred to as rubbers with low residual unsaturation content and are preferred when the vulcanizate needs good thermal stability or oxidation stability. The low-saturation residual rubber grades desirably have less than 10% by weight repeating units with saturation. Desirably, rubbers, acrylate rubber and epichlorohydrin rubber are excluded. For the purposes of the present invention, the copolymers will be used to define polymers of two or more monomers, and the polymers may have repeating units of one or more different monomers. The rubber is desirably an olefin rubber like rubber type EPDM. EPDM-type rubbers are generally terpolymers derived from the polymerization of at least two different monoolefin monomers having from 2 to 10 carbon atoms, preferably from 2 to 4 carbon atoms, and at least one polyunsaturated olefin having 5 carbon atoms. at 20 carbon atoms. Said monoolefins desirably have the formula CH 2 = CH-R wherein R is H or an alkyl of 1 to 12 carbon atoms and preferably are ethylene and propylene. Desirably, the repeating units of at least two monoolefins (preferably ethylene and propylene) are present in the polymer at weight ratios of 25:75 to 75:25 (ethylene: propylene) and constitute from about 90 to about of 99.6 percent by weight of the polymer. The polyunsaturated olefin can be a straight, branched, cyclic, bridged ring, bicyclic, fused ring bicyclic, etc. compound, and preferably is a non-conjugated diene. Desirably the repeating units of the unconjugated polyunsaturated olefins is from about 0.4 to about 10 weight percent of the rubber. The rubber may be a butyl rubber, halobutyl rubber or a halogenated (for example brominated) copolymer of p-alkylstyrene and an isomonoolefin of 4 to 7 carbon atoms. "Butyl rubber" is defined as a polymer comprising predominantly isobutylene repeating units but including some repeating units of a monomer that provides sites for crosslinking. The monomers that provide sites for crosslinking can be a polyunsaturated monomer such as a conjugated diene or divinylbenzene. Desirably from about 90 to about 99.5 percent by weight of the butyl rubber are repeating units derived from the polymerization of isobutylene, and from about 0.5 to about 10 percent by weight of the repeating units are from at least one polyunsaturated monomer having from 4 to 12 carbon atoms. Preferably, the polyunsaturated monomer is sopropene or divinylbenzene. The polymer can be halogenated or further improve the crosslinking reactivity. Preferably, the halogen is present in amounts of about 0.1 to about 10 weight percent, most preferably from about 0.5 to about 3.0 weight percent based on the weight of the halogenated polymer; preferably, the halogen is chlorine or bromine. The brominated copolymer of p-alkylstyrene, having about 9 to 12 carbon atoms, and an isomonoolefin, having 4 to 7 carbon atoms, desirably has from about 88 to about 99 weight percent of an isomonoolefin, very desirably from about 92 to about 98 weight percent, and from about 1 to about 12 weight percent of p-alkylstyrene, most desirably from about 2 to about 8 weight percent based on the weight of the copolymer before halogenation. Desirably, the alkylstyrene is p-methylstyrene and the isomonoolefin is isobutylene. Desirably, the bromine percentage is from about 2 to about 8, very desirably from about 3 to about 8, and preferably from about 5 to about 7.5 weight percent based on the weight of the halogenated copolymer. The halogenated copolymer is in a complementary amount, that is, from about 92 to about 98, most desirably from about 92 to about 97, and preferably from about 92.5 to about 95 weight percent. These polymers are commercially available from Exxon Chemical Co. Other rubber such as natural rubber or homo or copolymers of at least one conjugated diene can be used in dynamic vulcanization. These rubbers have a greater unsaturation than the rubber EPDM and the butyl rubber. The natural rubber and said homo or copolymers of a diene can optionally be partially hydrogenated to increase the thermal and oxidation stability. Synthetic rubber may be non-polar or polar depending on the comonomers. Desirably, the homo or copolymers of a diene have at least 50 percent by weight repeating units of at least one conjugated diene monomer having from 4 to 8 carbon atoms. The comonomers can be used and include aromatic vinyl monomers having from 8 to 12 carbon atoms and acrylonitrile or alkyl-substituted acrylonitrile monomers having from 3 to 8 carbon atoms. Other comonomers, desirably used, include monomer repeating units having unsaturated dicarboxylic acid unsaturated carboxylic acids, unsaturated anhydrides of dicarboxylic acids, and include divinylbenzene, alkyl acrylates and other monomers having from 3 to 20 carbon atoms. Examples of synthetic rubbers include synthetic polyisopropene, polybutadiene rubber, styrene-butadiene rubber, butadiene-acrylonitrile rubber, etc. Synthetic functionalized rubbers with amino, functionalized with carboxy or functionalized with epoxy can be used, and examples of these include the natural rubbers EPDM, and functionalized with epoxy. These materials are commercially available. The thermoplastic vulcanizates of this description are generally prepared by melt blending semicrystalline polyolefins (for example polypropylene), rubber and other ingredients (filler, plasticizer, lubricant, stabilizer, etc.) in a mixer heated to a temperature higher than the temperature of fusion of semicrystalline polypropylene. Fillers, plasticizers, additives, etc. Optionals can be added at this stage or later. After sufficient mixing in the molten state to form a well-mixed mixture, the vulcanizing agents (also known as curators or crosslinkers) are generally added. In some embodiments, it is preferred to add the vulcanizing agent in the solution with a liquid, for example rubber processing oil, or in a masterbatch that is compatible with the other components. It is convenient to follow the progress of vulcanization by monitoring the mixing torque or mixing energy requirements during mixing. The curve of the mixing torque or mixing energy generally passes through a maximum after which the mixing can be continued in some way for a longer time to improve the manufacturing capacity of the mixture. If so desired, you can add some ingredients after completing the dynamic vulcanization. The random thermoplastic ethylene copolymer (s) may be added before, during or after vulcanization. After the discharge of the mixer, the mixture containing the vulcanized rubber and the thermoplastic can be milled, crushed, extruded, pelletized, injection molded or processed by any other desirable technique. It is usually desirable to allow the fillers and a portion of any plasticizer to be distributed in the semicrystalline rubber or polypropylene phase before the rubber phase or phases are crosslinked. The crosslinking (vulcanization) of rubber may occur in a few minutes or less depending on the mixing temperature, shear rate and activators present for curing. Suitable cure temperatures include from about 120 ° C or 150 ° C for a semicrystalline polypropylene phase to about 250 ° C, temperatures of about 150 ° C or 170 ° C to about 225 ° C or more are particularly preferred. 250 ° C. The mixing equipment can include Banbury ™ mixers, Brabender ™ and some mixing extruders. The thermoplastic vulcanizate may include a variety of additives. The additives include particulate fillers such as carbon black, silica, titanium dioxide, color pigments, clay, zinc oxide, stearic acid, stabilizers, anti-degradants, flame retardants, processing aids, adhesives, thickeners, plasticizers, wax , staple fibers (such as wood cellulose fibers) and extender oils. When extender oil is used, it may be present in amounts of about 5 to about 300 parts by weight per 100 parts by weight of the semicrystalline polypropylene and rubber mixture. The amount of extender oil (eg, hydrocarbon oils and ester plasticizers) can also be expressed from about 30 to 150 parts, and most desirably from about 70 to 200 parts by weight per 100 parts by weight of said rubber. When non-black fillers are used, it is desirable to include a coupling agent so that the interface between the non-black fillers and the polymers is made compatible. The desirable amounts of carbon black, when present, are from about 5 to about 250 parts by weight per 100 parts by weight of the rubber. The thermoplastic vulcanized compositions of the invention are useful for making a variety of items such as rims, hoses, belts, molds, gaskets and molded parts. They are particularly useful for making articles by extrusion, injection molding, blow molding and compression molding techniques. They are also useful for modifying thermoplastic resins and in particular polyolefin resins. The compositions can be blended with thermoplastic resins using conventional mixing equipment by making a rubber-modified thermoplastic resin. The properties of the modified thermoplastic resin depend on the amount of the mixed thermoplastic vulcanized composition. The force-tension properties of the compositions are determined in accordance with the test procedures set forth in ASTM D412. These properties include voltage adjustment (TS), resistance to the final voltage (UTS), modulus at 50% (M50), modulus at 100% (M100), and an elongation at the final break (UE). Tear resistance is measured in accordance with ASTM D623. Tenacity is measured in accordance with ASTM D2240, with a challenge of 5 seconds, using either the Shore A or Shore D scale. The compression fit (CS) is determined in accordance with ASTM D-395, method B, by Compress the sample for 22 hours at 100 ° C. Oil swelling (OS) (percentage change in weight) is determined in accordance with ASTM D-471 by immersing the sample in IRM 903 oil and, unless otherwise specified, for 24 hours at 125 ± 2 ° C . Especially preferred are compositions of the invention which are rubber compositions having tension adjustment values of about 50% or less, whose compositions meet the definition of rubber in accordance with the definition of ASTM standards, volume 28, page 756 (D1566). The compositions that are especially preferred are rubber compositions having a Shore D toughness of 60 or less, or a 100% modulus of 18 MPa or less, or a Young's modulus of less than 250 MPa.

EXAMPLES Tables I through XI provide additional experimental data on polyethylenes and copolymers of mixed thermoplastic random ethylene, either with thermoplastic vulcanizates or precursors of thermoplastic vulcanizates. The ethylene homopolymers and some of the ethylene copolymers that are not really random when mixed with the thermoplastic vulcanizates or their precursors are control examples. Examples of the ethylene thermoplastic random copolymers blended with thermoplastic vulcanizates or their precursors are examples of the present invention. Tables I and II show the composition of various ethylene copolymers and the composition of various thermoplastic vulcanizates used in subsequent tables. Table X also shows various ethylene polymers or copolymers. The trade name Exact ™ is used by Exxon for some of its ethylene polymers polymerized with metallocene. The trade name Engage ™ is used by DuPont Dow Elastomers. In Table I, several experimental polymers (eg, those with SLP prefixes) from Exxon were used in the experimentation, but similar ethylene copolymers are currently available under the trade name Exact. Table III shows the variation in physical properties achieved with various quantities of four different ethylene-ethylene-1-butene random ethylene-ethylene random copolymers. The Shore A tenacity may increase or decrease from the addition of the random thermoplastic ethylene copolymers depending on the particular thermoplastic random ethylene copolymer used. The tensile strength usually increases along with the final elongation and relative tenacity. Oil swelling and set compression at 100 ° C typically increases with the addition of the random thermoplastic ethylene copolymer. Control samples (with a suffix C) are generally thermoplastic vulcanized without a random thermoplastic ethylene copolymer. Table IV illustrates mixtures of thermoplastic vulcanizate and thermoplastic random ethylene copolymers and their physical properties. These copolymers vary from those shown in Table II and which are copolymers of ethylene with 1-octene. Tables V and VI illustrate additional mixtures of ethylene or ethylene copolymers with thermoplastic vulcanizates. In these examples, the final elongation increases. Table VII lists various conventional ethylene copolymers used in subsequent tables. Table VIII illustrates mixtures of conventional ethylene copolymers and thermoplastic vulcanizates. The elongation at rupture of the mixtures and the tenacity are generally lower than the control without ethylene copolymers. There are increases in elongation and toughness with Vistalon ™ 808 and 4709, but adversely affect other properties such as increased oil absorption.

Table IX shows mixtures of the precursors of a thermoplastic vulcanizate or a thermoplastic vulcanizate with a thermoplastic random ethylene copolymer. The purpose of this table is to demonstrate that the thermoplastic random ethylene copolymer can be added before or after curing and some changes in physical properties can be anticipated. Generally, if added after the cure, it is believed that the thermoplastic random ethylene copolymer causes a lower final Brabender torque, a slightly greater elongation at break and, as a result of greater elongation, a slightly higher toughness. The absorption of oil is expected to decrease from the addition of the thermoplastic random ethylene copolymer after vulcanization. Table X shows several additional polymers or copolymers of ethylene, both inside and outside the definition of random ethylene thermoplastic copolymer. Table XI shows the physical properties of the mixtures of a thermoplastic vulcanizate and the copolymers of ethylene and the random ethylene thermoplastic copolymers. The final elongation increases to a greater extent for the thermoplastic random ethylene copolymers than for the different copolymers and homopolymers. Table XII was prepared to better illustrate the difference between thermoplastic random ethylene copolymers and other copolymers of similar total comonomer concentration. The physical properties shown are the final elongation and modulus at 100 percent for the mixtures of thermoplastics and homopolymers and ethylene copolymers. The first and third examples are thermoplastic random ethylene copolymers according to this description. The second and fourth examples are not within the description of a thermoplastic random ethylene copolymer of the present disclosure. As can be seen from the data, the final elongation is much better for the first and third examples than for the other examples outside the scope of the present disclosure. As can be seen from the data of the module at 100 percent, the first and third compositions have a lower module, that is, a softer one than the second and fourth compositions that are outside the scope of the present disclosure. Table XIII was prepared to illustrate that a TPV using a butyl rubber, a nitrile rubber or natural rubber instead of EPDM rubber will have an improved final elongation and improved tensile strength when mixed with an ethylene copolymer random (plastomer).

Available from Exxon * Available from DuPont Dow Elastomers ** Melt index is in accordance with ASTM D-1238 (E) The residual value of thermoplastic vulcanizates being conventional TPV components that include oils, fillers, processing aids, healers, etc.

-J t 00 or w OR) Vistalon ™ is available from Exxon in ? C? 00 or Although in accordance with the patent statutes the best mode and the preferred embodiment have been established, the scope of the invention is not limited by them, instead it is defined by the scope of the appended claims.

Claims (13)

NOVELTY OF THE INVENTION CLAIMS

1. A thermoplastic vulcanized composition comprising from about 20 to about 85 parts by weight of rubber and from about 15 to about 80 parts by weight of semi-crystalline polypropylene, wherein said parts by weight are based on 100 parts by weight of said rubber, and said polypropylene, and a thermoplastic random ethylene copolymer having a peak melting temperature of about 55 to about 100 ° C, wherein the weight ratio of said polypropylene to said random ethylene copolymer is closely from 100: 5 to 100: 150 and wherein said random ethylene copolymer comprises from about 60 to about 95 weight percent methylene repeating units and from about 5 to about 30 weight percent units of repeating one or more other ethylenically unsaturated monomers based on the weight of said random ethylene copolymer; wherein said rubber comprises an ethylene-propylene-diene rubber, natural rubber, butyl rubber, halogenbutyl rubber, halogenated rubber, p-alkylstyrene copolymer and at least one somonoolefin having from 4 to 7 carbon atoms, a rubber homopolymer of a conjugated diene having from 4 to 8 carbon atoms, or a rubber copolymer having at least 50% by weight of repeating units of at least one conjugated diene having from 4 to 8 atoms of carbon or combinations thereof; and wherein said thermoplastic vulcanizate composition has a tension adjustment of about 50% or less as determined by ASTM D41

2. 2. The composition according to claim 1, further characterized in that said rubber was dynamically vulcanized in the presence of at least said semicrystalline polypropylene thus forming said thermoplastic vulcanizate.

3. The composition according to claim 1, further characterized in that said random ethylene copolymer comprises from about 70 to about 90 weight percent of ethylene repeating units and from about 10 to about 30 percent by weight of repeating units of at least one monoolefin having from 3 to 8 carbon atoms.

4. The composition according to claim 1, further characterized in that said peak melting temperature is from about 55 to about 90 ° C.

5. The composition according to claim 4, further characterized in that said random ethylene copolymer comprises from about 70 to about 90 weight percent of ethylene repeating units and from about 10 to about 30 percent by weight of repeating units of at least one monoolefin having from 3 to 8 carbon atoms.

6. The composition according to claim 5, further characterized in that said random ethylene copolymer comprises from about 65 to about 85 weight percent of ethylene repeating units and from about 15 to about 25 percent by weight of repeating units of at least one monoolefin having from 3 to 8 carbon atoms.

7. The composition according to claim 1, further characterized in that said rubber comprises ethylene-propylene-diene rubber.

8. The composition according to claim 1, further characterized in that said rubber comprises butyl rubber, halogenbutyl rubber or a halogenated rubber copolymer of p-alkylstyrene copolymer and isobutylene.

9. The composition according to claim 1, further characterized in that said rubber comprises natural rubber.

10. The composition according to claim 1, further characterized in that said rubber comprises a rubber homopolymer of a conjugated diene having from 4 to 8 carbon atoms or a rubber of copolymer having at least 50 weight percent of repeating units of at least one conjugated diene having from 4 to 8 carbon atoms or combinations thereof.

11. A process for preparing a thermoplastic vulcanized composition comprising: mixing from about 20 to about 85 parts by weight of rubber and from about 15 to about 80 parts by weight of a semi-crystalline polypropylene, wherein said parts by weight are based on 100 parts by weight of said rubber and said semi-crystalline polypropylene, and a thermoplastic random ethylene copolymer having a peak melting temperature of about 55 to about 100 ° C; wherein the weight ratio of said polypropylene to said random ethylene copolymer is from about 100: 5 to 100: 150, and wherein said random ethylene copolymer comprises from about 60 to about 95 weight percent units of repeating ethylene and from about 5 to about 30 weight percent repeat units of 1 or more different ethylenically unsaturated monomers based on the weight of said random ethylene copolymer, and dynamic vulcanization of said rubber after mixing with said semi-crystalline polypropylene, or said random ethylene copolymer, or combinations thereof, to provide a thermoplastic vulcanized composition having a tension adjustment of about 50 percent or less as determined by ASTM D4

12. 12. The process according to claim 11, wherein said random ethylene copolymer has a peak melting temperature of about 55 to about 90 ° C.

13. The process according to claim 11, further characterized in that said thermoplastic ethylene copolymer is added and mixed after vulcanizing said rubber.