MXPA99005467A - Abrasion-resistant, silane-crosslinkable polymer and polymer blend compositions - Google Patents

Abstract

A crosslinkable elastomer composition that includes a silane grafted ethylene alpha-olefin interpolymer elastomer with a hardness (Shore A)=85 and, optionally, a crystalline olefin polymer. Exposure to moisture converts the crosslinkable composition into a nonporous, grafted and crosslinked elastomer composition that has a hardness (Shore A)=85 and an abrasion resistance that is greater than that of the crosslinkable composition. It is also greater than that of an ungrafted elastomer composition that is prepared from the same elastomer(s) and optional crystalline olefin polymer(s) and is substantially free of grafting and crosslinking. Articles of manufacture fabricated from these compositions include shoe soles.

Description

POLYMER RETICULABLE BY SILAN RESISTANT TO ABRASION AND COMPOSITIONS OF POLYMERIC MIXTURES Field of the invention This invention is generally concerned with crosslinkable polymeric compositions. This invention is concerned in particular with such compositions wherein crosslinking (or crosslinking) occurs through a portion of vinyl silane. This invention is also concerned in particular with polymeric compositions which include an elastomer and a crystalline polymer, such as a polypropylene homopolymer or a propylene / alpha-olefin copolymer (α-olefin). This invention is more particularly concerned with polymeric compositions wherein the elastomeric components have a hardness (Shore A) of 85 or less (< 85).

BACKGROUND OF THE INVENTION A teaching accepted in the literature is that the wear rates in the materials in which the polymers are included can be correlated with the mechanical properties of such materials. The mechanical properties include hardness, tensile strength and elongation at break. See, for example, J. K. Lancaster, "Relationship Between the Wear of Polymers 30529 BEF 'and Their Mechanical Properties, "Proceedings of the Institution of Mechanical Engineers 1968-69, volume 183, part 3P, pages 98-106, Anne E. Bovari and Sherry B. Glenn, in" Selecting Materials for Wear Resistance ", Plastics Engineering, December 1995, pages 31-33, make several observations with respect to abrasion on page 32. "Abrasion occurs in contacts in which one surface is considerably harder than the other, for example, paper of sandpaper on wood. "They indicate that," in such a situation, the roughness of the hardest surface penetrates the softest surface and as a result of relative movement the material is displaced from the softer body. "They suggest that the generation of particles of Wear should be low and the abrasion resistance should be high when a material has a high hardness or resistance to penetration by asperities.The standard test method of the American Society for Testing a nd Materials (ASTM) for abrasion resistance is ASTM D 1630-83. The test method is particularly suitable for determining the abrasion resistance of a vulcanized rubber (or rubber) or other compounds used in shoe soles and heels. The method employs an abrasion machine from the National Bureau of Standards (NBS).

Mike Wilson in "Slip Resistance Performance of Soling Materials", SATRA Bulletin, May 1996, pages 77-79, a publication produced by SATRA Footwear Technology Center, suggests on page 78 that a minimum coefficient of friction (COF) for soles and Shoe heels in dry and wet quarry tile is 0.3. He also suggests on page 79 that athletic shoes and for industrial applications may be more demanding in terms of slip resistance and require a COF of at least 0.4, sometimes de-at least 0.6. - In order to obtain an acceptable life of the product for soles and shoe heels, an improvement in abrasion resistance is desirable. By following the teachings of Lancaster and Bovari et al. , a procedure to improve the resistance to abrasion is to increase the hardness in order to minimize the penetration by roughness. However, this procedure has its limits. At some point, the hardness is so high that consumers will not accept the use of material in soles and heels, shoes because they are uncomfortable. Shoe designers also have hardness limitations because the increasingly hard materials have fewer processing options. There is a need, particularly for end-use applications of footwear, such as soles and heels, to improve the abrasion resistance of a material without increasing its hardness to a level that renders it unacceptable from a consumer or designer's perspective.

BRIEF DESCRIPTION OF THE INVENTION One aspect of the invention is a non-porous, grafted and crosslinked elastomeric composition comprising at least one ethylene / alpha-olefin interpolymer (EAO) elastomer having a hardness (Shore A) < 85 and optionally a crystalline olefin polymer, the elastomer is grafted with a silane portion that promotes crosslinking of the grafted elastomer in the presence of moisture and then is crosslinked after exposure to moisture, the grafted and crosslinked elastomeric composition has a hardness ( Shore A) < 85 and an abrasion resistance (ASTM D 1630-83, Radent (or abrasion machine) of the NBS) which is greater than that of either a crosslinkable composition which is the elastomeric composition. before grafting and cross-linking or a similar composition prepared by using an ungrafted version of the same ethylene / alpha-olefin interpolymer elastomer. The abrasion resistance of the grafted and crosslinked elastomeric composition is desirably at least 25 percent (%) greater, preferably at least 50% greater than that of either the elastomeric composition prior to grafting and crosslinking or the similar composition. A second aspect of the invention is a crosslinkable elastomeric composition comprising at least one grafted EAO interpolymer elastomer having hardness (Shore A) < 85 and optionally at least one crystalline olefin polymer, the elastomer is grafted with a silane portion that promotes crosslinking of the grafted elastomer in the presence of moisture, the crosslinkable composition has an abrasion resistance and then exposure to moisture produces a grafted crosslinked elastomeric composition having an abrasion resistance, the abrasion resistance of the crosslinked composition is greater than the abrasion resistance of the crosslinkable composition, desirably at least (>) 25% higher, preferably, > 50% higher DESCRIPTION OF THE PREFERRED EMBODIMENTS Unless otherwise stated herein, all ranges include both endpoints. "Ethylene polymers" means a copolymer of EAO (ethylene alpha-olefin) or a copolymer of EAO modified by diene. Exemplary polymers include ethylene / propylene (EP) copolymers, ethylene / octene (EO) copolymers, ethylene / butylene (EB) copolymers and ethylene / propylene / diene interpolymers (EPDM). More specific examples include linear ultra low density polyethylene (ULDPE) (eg, Attane ™ manufactured by the Dow Chemical Company), homogeneously branched linear ethylene / alpha-olefin copolymers (eg, Tafmer ™ from Mitsui Petrochemicals Company Limited and Exact ™ by Exxon Chemical Company), homogeneously branched substantially linear ethylene / alpha-olefin polymers (eg, Affinity ™ polymers available from The Dow Chemical Company and Engage® polymers available from Dupont Dow Elastomers, LLC) and ethylene copolymers polymerized by high pressure free radicals, such as ethylene / vinyl acetate (EVA) polymers (e.g., ELVAX ™ polymers manufactured by EI Dupont de Nemours and Company). The most preferred olefin polymers are homogenously linear substantially linear branched ethylene copolymers with a density (measured according to ASTM D-792 standard of 0.85 to 0.92 g per cubic centimeter (g / cm3) especially 0.85 to 0.90 grams / cm3 and a melt flow index or MI (measured in accordance with ASTM D-1238 (190 ° C / 2.16) from 0.01 to 500, preferably from 0.05 to 30 grams per 10 minutes (g / 10 minutes) The substantially linear ethylene polymers and the various functionalized ethylene copolymers such as EVA (containing 0.5 to 50% by weight units derived from vinyl acetate) are especially preferred EVA polymers having an MI (ASTM D - 1238) from 0.01 to 500, preferably 0.05 to 150 g / 10 minutes are very useful in the present invention. "Substantially linear" means that a polymer has a fundamental chain substituted with 0.01 to 3 long chain branches per 1,000 carbons in the fundamental chain. "Long chain branching" or "LCB" means a chain length greater than or equal to 6 carbon atoms. At a higher level of this length, nuclear magnetic resonance spectroscopy based on carbon 13 (13 C NMR can not distinguish or determine a real number of carbon atoms in the chain.) In some instances, a chain length may be so long As the fundamental chain of the polymer to which it is attached, for the ethylene / α-olefin copolymers, the long chain branch is longer than the short chain branch resulting from the incorporation of the α-olefin (s). ) to the polymer backbone "Interpolymer" refers to a polymer having at least two monomers polymerized therein, including, for example, copolymers, terpolymers and tetrapolymers, including in particular a polymer prepared by the polymerization of ethylene with at least one comonomer, usually an α-olefin of 3 to 20 carbon atoms (3 to 20 carbon atoms) Illustrative α-olefins include propylene, l-butene, 1-hexene, 4-methyl-1- pen Teno, 1-heptene, 1-octene and styrene. The α-olefin is desirably an α-olefin of 3 to 10 carbon atoms. Preferred copolymers include copolymers of EP and EO. Illustrative terpolymers include an ethylene / propylene / octene terpolymer also as ethylene terpolymers, an α-olefin of 3 to 20 carbon atoms and a diene such as dicyclopentadiene 1,4-hexadiene, 1,3-pentadiene (piperylene) - or 5-ethylidene-2-norbornene (ENB). Terpolymers are also known as EPDM terpolymers wherein the α-olefin is propylene or generically as terpolymers of EAODM. Substantially linear ethylene α-olefin interpolymers ("SLEP" or "substantially linear ethylene polymers") are characterized by a narrow molecular weight distribution (MWD) and a narrow short chain branching distribution (SCBD) and can be prepared as is described in US Pat. No. 5,272,236 and 5,278,272, the relevant portions of both are incorporated herein by reference.The SLEP exhibit outstanding physical properties by virtue of its narrow MWD and its narrow SCBD coupled with the LCB. LCB in these olefinic polymers allows faster processing (faster mixing, faster processing speeds) and allows for more efficient free radical crosslinking US Patent 5,272,236 (column 5, line 67 to column 6, line 28) describes the SLEP production via a continuous controlled polymerization process by using at least one area but allows multiple reactors at a sufficient polymerization temperature and pressure to produce a SLEP having desired properties. Polymerization is preferably carried out via a solution polymerization process at a temperature of ~ 20 ° C to 250 ° C using catalytic technology of restricted geometry. Suitable restricted geometry catalysts are described in column 6, line 29 to column 13, line 50 of US patent 5,272,236. These catalysts comprise a metal coordination complex comprising a metal of groups 3-10 or the series of lanthanides of the periodic table of the elements and a delocalized pi-linked portion substituted with a restricting-inducing portion. The complex has a restricted geometry around the metal atom such that the angle in the metal between the centroid of the substituted, delocalised pi-linked portion and the center of at least one remaining substituent is less than that angle in a complex similar that contains a similar pi-linked portion that lacks such a substituent that induces the restriction. If such complexes comprise more than one delocalised substituted pi-linked portion., only one such portion for each metal atom of the complex is a substituted, delocalised, cyclized pi-linked portion. The catalyst further comprises an activating co-catalyst such as tris (pentafluoro-phenyl) borane. Specific catalytic complexes are discussed in the US patent 5,272,236 in the column, line 57 to column 8, line 58 and in the US patent 5,2 ^ 78,272 in column 7, line 48, to column 9, line 37. The North American patent 5,272,236 in column 8, lines 34-49 and US patent 5,278,272 in column 9, lines 21-37 describe specific catalysts as complexes: (tert-butylamido) (tetramethyl-? 5-cyclopentadienyl) -1 dichloride, 2-ethanedylzirconium, (tert-butylamido) dichloride (tetramethyl-? 5-cyclopentadienyl) -1, 2-ethanedyltitanium, (methylamido) dichloride (tetramethyl-? 5-cyclopentadienyl) -1,2-ethanedylzirconium, (methylamido) dichloride ) (tetramethyl-? 5-cyclopentadienyl) -1, 2-ethanedithyium, dichloride (ethylamido) (tetramethyl-? 5-cyclopentadienyl) -methylene-titanium, (tert-butylamido) -dibenzyl (tetramethyl-? 5-cyclopentadienyl) si-lanzinium dibenzyl, (benzylamido) dimethyl- (tetramethyl-? 5-cyclopentadienyl) -silantitanium dichloride, (f enylphosphido) dimethyl (tetramethyl-? 5-cyclopentadienyl) silancirconium dibenzyl and (tert-butylamido) -dimethyl (tetramethyl-? 5-cyclopentadienyl) silantitanium dimethyl. The teachings regarding catalytic complexes in general and these specific complexes are incorporated by reference. A SLEP (substantially linear ethylene polymer) is characterized by a narrow molecular weight distribution (MWD) and, if it is an interpolymer, by a narrow distribution of the comonomer. A SLEP is also characterized by a low residue content, specifically in terms of residues - catalysts, unreacted comonomers and low molecular weight (MW) oligomers generated during polymerization. A SLEP is further characterized by a controlled molecular architecture that provides good processability although the MWD is narrow in relation to conventional olefin polymers. A preferred SLEP has a variety of distinctive characteristics, one of which is a comonomer content that is between 20 and 80 weight percent (% by weight), more preferably between 30 and 70 weight% of ethylene and the rest consists of one or more comonomers. The SLEP comonomer content can be measured by using infrared (IR) spectroscopy according to method B of ASTM D-2238 or ASTM D-3900. The comonomer content can also be determined by 13 C NMR spectroscopy. The additional distinguishing characteristics of SLEP include I2 and the melt flow ratio (MFR or I10 / I2) • Interpolymers desirably have an I2 (ASTM D-1238, condition 190 ° C / 2.16 kilograms (Kg) (previously condition E)); of 0.01-500 g / 10 minutes, more preferably 0.05-150 grams / 10 minutes. SLEPs also have an I10 / I2 (ASTM D-1238) > 5.63, preferably 6.5-15, more preferably 7-10. For a SLEP, the I10 / I2 ratio serves as an indication of the degree of LCB, such that a higher I10 / I2 ratio is equal to a higher degree of LCB in the polymer. A further distinguishing feature of a SLEP is MWD (Mw / Mn or "polydispersity index"), as measured by gel permeation chromatography (GPC). The Mw / Mn ratio is defined by the equation: The MWD is desirably > 0 and < 5, especially 1.5-3.5 and preferably 1.7-3. A homogenously branched SLEP surprisingly has an MFR that is essentially independent of its MWD. This contrasts markedly with homogeneously linear heterogeneously branched and branched homogeneous linear branched ethylene copolymers where the MWD must be increased to increase the MFR. A SLEP can be further characterized because it has a critical cutoff speed at the beginning of the surface melt fracture (OSMF) of at least 50% greater than the critical cutoff speed to the OSMF of a linear olefin polymer having an I2 and Mw / Mn similar. SLEPs that meet the criteria mentioned above are properly produced by geometry-restricted catalysis by Dow Chemical and DuPont Dow Elastomers L.L.C. For many elastomeric applications, such as insulation of wires and cables, weatherstripping, fibers, seals, gaskets, foams, footwear, hoses, pipes, bellows and belts, certain physical properties, such as tensile strength, hardened of compression and end-use temperature of articles made from one or more olefins can be improved by introducing chemical bonds between the molecular chains that make up the polyolefin (s). As used herein, "crosslinking (s)" (or cross-linking) refers to the presence of two or more chemical bonds between the same two chain molecules. Where there is only one chemical bond between two molecule chains, it is referred to as "branch point" or "branch". Cross-links (or cross-links) and branch points can be introduced between different molecular chains by any of a variety of mechanisms. One mechanism involves the grafting of a chemically reactive compound to individual molecular chains or polymer backbones that constitute a bulky polymer such that the grafted compound on a chain can subsequently react with a similar grafted compound on another chain to form the crosslink, of branch or both. The crosslinking of the silane exemplifies this mechanism. Any silane or mixture of such silanes that will effectively graft the components to the elastomeric compositions of the present invention, especially the elastomeric phase, can be used as the silane portion in the practice of this invention. Suitable silanes include of the general formula: CH2"= --CC f- - ((lCC-0) x (C H2 H2n) and SiR3 in which R 'is a hydrogen atom or methyl group, x and y are 0 or 1 with the proviso that when x is 1, y is 1; n is an integer from 1 to 12 inclusive, preferably from 1 to 4 and each R is independently a hydrolyzable organic group such as an alkoxy group of 1 to 12 carbon atoms (eg, methoxy, ethoxy, butoxy), an aryloxy group (e.g., phenoxy), an aralkoxy group (e.g., benzyloxy), an aliphatic acyloxy group of 1 to 12 carbon atoms (e.g., formyloxy, acetyloxy, propanoyloxy), amino or substituted amino groups (alkylamine, arylamino) or a lower alkyl group (of 1 to 6 carbon atoms), with the proviso that not more than the three R groups is an alkyl group ( for example, vinyl dimethylmethoxy silane). The use of "C" with a range of subscript denotes the number of carbon atoms in, for example, a lower alkyl group. Silanes useful in the care of silicones having ketoxy hydroxyl groups such as vinyl tris (methylethylketoamino) silane are also suitable. Useful silanes include unsaturated silanes comprising an ethylenically unsaturated hydroxycarboxyl group, such as a vinyl, allyl, isopropyl, butyl, cyclohexenyl or gamma- (meth) acryloxy allyl group, and a hydrolyzable group such as, for example, a hydrocarbyloxy group, hydrocarbonyloxy or hydrocarbylamino group Examples of hydrolyzable groups include methoxy, ethoxy, formyloxy, acetoxy, propionyloxy and alkyl or arylamino groups The preferred silanes are the unsaturated alkoxy silanes which can be grafted onto the polymer.The groups vinyl trimethoxy silane, vinyl triethoxy silane, gamma- (meth) acryloxy propyl trimethoxy silane and mixtures of these silanes are the preferred silanes for use in establishing cross-links or cross-links.The amount of silane used in the practice of this invention can vary widely depending on the nature of the silanes. components of the elastomeric phase, the silane, the processing conditions, the ef hydration phenomenon, the final application and similar factors, but normally is greater than or equal to 0.1, preferably used greater than or equal to 0.3, more preferably greater than or equal to 0.4 parts of silane per one hundred parts of elastomeric resin (phr) . Considerations of convenience and economy are usually the main limitations in terms of the maximum amount of silane used in the practice of this invention. Normally, the maximum amount of silane is not greater than 3.5, preferably not exceeding 2.5 more preferably not exceeding 2.0 phr. As used in "phr", "resin" means the elastomer plus any other polymer (s) included with the elastomer during grafting. An amount of less than 0.1% by weight is undesirable because it does not result in branching, sufficient cross-linking or both to give improved morphological and rheological properties. An amount of more than 3.5% by weight is undesirable because the elastomeric domains or elastomeric phase becomes crosslinked at a level that is too high to result in a loss of impact properties. The silane is grafted to the resin (elastomer plus any other polymer included with the elastomer during grafting) by any conventional method, usually in the presence of a free radical indicator, such as a peroxide or an azo compound or by ionization radiation. Organic initiators, especially peroxide initiators are preferred. Examples of peroxide initiators include - ^ - dicumyl peroxide, di-tert-butyl peroxide, t-butyl perbenzoate, benzoyl peroxide, eumeno hydroperoxide, t-butyl perbenzoate, benzoyl peroxide, eumenohydroperoxide, t-butyl peroctoate, methyl ethyl ketone peroxide, 2,5-dimethyl-2,5-di (t-butyl peroxyhexane), lauryl peroxide and tert-butyl tert-acetate An appropriate azo compound is azobisisobutyl nitrite. The amount of the initiator may vary, but is normally present in an amount greater than or equal to 0.04 preferably greater than or equal to 0.05, phr Normally, the amount of the initiator is not greater than 0.15, preferably not greater than about 0.10 phr. The proportion of silane to the initiator can also vary widely, but a common ratio of silane: initiator is between 10: 1 and 30: 1, preferably between 18: 1 and 24: 1.

While any conventional method for grafting the silane to the resin can be used, a preferred method is to mix the two with the initiator in the first stage of a reactor extruder, such as a single screw or twin screw extruder, of preference one with a length / diameter ratio (L / D) of 25: 1 or greater. The grafting conditions may vary, but the melting temperatures are usually 160 ° C-280 ° C, preferably 190 ° C-250 ° C, depending on the residence time and the half-life of the initiator. - The curing is preferably accelerated with a catalyst and any catalyst that provides this function can be used in this invention. These catalysts generally include organic bases, carboxylic acids and organometallic compounds in which they include organic titanates and complexes or carboxylates of lead, cobalt, iron, nickel, zinc and tin. Illustrative catalysts include dibutyltin dilaurate, dioctyltin maleate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octoate, lead naphthenate, zinc caprylate, and cobalt naphthenate. Tin carboxylate, especially dibutyltin dilaurate and dioctyltin maleate and titanium compounds, especially 2-ethylhexide titanium are particularly effective for this invention. The catalyst is preferably dibutyltin dilaurate. The catalyst (or mixture of catalysts) is present in a catalytic amount, commonly between 0.005 and 0.3 phr, based on the weight of the elastomer. Cross-links (or cross-links), branch points or both, resulting from the curing process can be formed between two elastomeric molecules, two crystalline polyolefin polymer molecules, an elastomeric molecule and a crystalline polyolefin polymer molecule or any combination thereof. The crosslinking catalyst, while preferred, is not necessary to effect the crosslinking of a silane-grafted elastomer.The crosslinking may occur with the same "as long as the required elastomer and the crystalline polymer molecules are present. As time passes by leaving compositions or articles containing a silane grafted elastomer in an atmosphere filled with moisture or vapor, where time is not critical and energy savings are desired, a simple humidity environment without added heating will suffice. The elastomeric compositions of the present invention can be manufactured s in parts, sheets or other form when using any of a variety of conventional procedures. These methods include, for example, injection molding, blow molding and extrusion, injection molding is preferred. The compositions can also be formed, spun or drawn into films, laminates of multilayers or extruded sheets or can be compounded with one or more organic or inorganic substances in any machine suitable for such purposes. The manufacturing can be carried out either before or after curing by moisture, but is preferably carried out before curing by moisture for ease of processing. - The crystalline olefin polymer is appropriately selected from an EAO polymer having an ethylene content of more than 85% by weight based on the weight of the copolymer, high density polyethylene and propylene / ethylene copolymers having an ethylene content of not more than 10% by weight, based on the weight of the copolymer. Suitable polypropylene resins include, for example, propylene homopolymer, random or disordered propylene / ethylene copolymers, propylene / ethylene block copolymers, disordered propylene / butene copolymers and propylene / ethylene / butene terpolymers. The preparation of polypropylene resins involves the use of Ziegler catalysts, which allow the stereoregular polymerization of propylene to form isotactic polypropylene. The catalyst used is usually a titanium trichloride in combination with aluminum diethylchloride as further described in the North American Cecchin patent., USP 4,177,160. The various types of polymerization processes used for the production of polypropylene include the suspension process, which is put into operation at a temperature of 50-90 ° C and a pressure of 0.5-1.5 MPa (5-15 atmospheres) and the gaseous phase and liquid monomer processes in which care must be taken to remove the amorphous polymer separation. The ethylene can be added to the reaction to form a polypropylene with ethylene blocks. Polypropylene resins can also be prepared by using any of a variety of metallocene, single-site, and restricted-geometry catalysts coupled with their associated processes. The polypropylene resins, when included as a component of the non-porous crosslinked grafted elastomeric compositions of the present invention are included in an amount of a range of 1-50 parts by weight (pbw) per one hundred pbw of the elastomer. The range is preferably 5-30 pbw. Polypropylene resins desirably have a melt flow rate (MFR) measured at 230 ° C and 2.16 kilograms (Kg), from 0.5-70 g / 10 minutes.

Extender oils, such as paraffinic oils, aromatic oils, naphthalenic oils, mineral oils and liquid polybutene can be used in the elastomeric, grafted and non-porous crosslinked compositions of the present invention. Naphthalene oils are preferred by ethylene / alpha-olefin copolymers and paraffinic oils are preferred by polymers of EPDM and EAODM. The extender oils perform functions such as reducing the viscosity of the composition and softening the compositions. They are optional components, but when present, they are normally used in quantity in a range of 1-150 pbw per 100 pbw of polymers contained in the compositions of the present invention. The range is preferably 15-100 pbw. A variety of additives be advantageously used in the compositions of this invention for other purposes such as the following, any one or more of which be used: antimicrobial agents, such as organometallic compounds, isothiazolones, organosulfur and mercaptans; antioxidants such as phenolics, secondary amines, phosphites and thioesters; antistatic agents such as quaternary ammonium compounds, amines and ethoxylated, glycerol, propoxylated compounds; fillers and reinforcing agents such as glass, metal carbonates such as calcium carbonate, metal sulfates such as calcium sulfate, talc, clays, silicas, carbon blacks, graph fibers and mixtures thereof; hydrolytic stabilizers; lubricants such as fatty acids, fatty alcohols, esters, fatty amides, metal stearates, paraffinic and microcrystalline waxes, silicones and esters of orthophosphoric acid; mold release agents such as fine particles or powdered solids, soaps, waxes, silicones, polyglycols and complex esters such as trimethylolpropanetristearate or penteritritol tetrastearate; pigments, dyes and colorants; plasticizers such as esters of dibasic acids (or their anhydrides) with monohydric alcohols such as o-phthalates, adipates and benzoates; thermal stabilizers such as organotin mercaptides, an octyl ester of thioglycolic acid and a barium or cadmium carboxylate; ultraviolet light stabilizers used as a hindered amine, an o-hydroxy-phenylbenzotriazole, a 2-hydroxy-4-alkoxybenzophenone, a salicylate, a cyanoacrylate, a nickel chelate and a benzylidene malonate and oxalanilide. A preferred hindered phenolic antioxidant is the antioxidant Irganox ™ 1076, available from Ciba Geigy Corp. Such additives, if used, do not normally exceed 45% by weight of the total composition and are advantageously 0.001-20% by weight, preferably 0.01 - 15% by weight and more preferably 0.1 - 10% by weight based on the total weight of the composition. Manufacturing articles that can be made from the non-porous grafted and crosslinked elastomeric compositions of the present invention include for example those selected from the group consisting of gaskets, membranes, sheets, shoe sole components, shoe upper components, axle or tree bushings and wear control items such as drawer joints and slides. Those skilled in the art will readily appreciate other articles of manufacture that can be made from the compositions of the present invention. The non-porous, grafted and crosslinked elastomeric compositions of the present invention, particularly when manufactured in shoe sole components, have a coefficient of friction (COF) measured in accordance with ASTM D-1894 standard, when using a masonry tile (dry and wet) of at least 0.3. The COF measured with wet masonry tile is beneficially at least 0.4, desirably at least 0.45, preferably at least 0.5 and more preferably at least 0.55. The COF, measured with dry masonry tile, is beneficially at least 0.4, desirably at least 0.6, preferably 0.9, more preferably at least 1.0. The same COF values are applied to the crosslinkable compositions of the present invention following crosslinking and fabrication. The following examples illustrate but do not explicitly or implicitly limit the present invention. Unless stated otherwise, all parts and percentages are by weight on a total weight basis.

EXAMPLES Four different ethylene / octene polymers or SLEP are used in the examples. All are available from DuPont Dow Elastomers L.L.C. Polymer A is available as Engage® EG8445. Polymer B is available as Engage® EG8448. Polymer C is an experimental polymer and polymer D is available as Engage® EG8200. Table I below lists the density in grams per cubic centimeter (g / cm3) MI, in g / 10 minutes and percent (%) of crystallinity for each of the polymers. The crystallinity of a polymer is determined by differential scanning calorimetry (DSC) on a DSC TA Instrument 2920 equipped with liquid nitrogen cooling accessories. Samples are prepared in the form of thin films and placed in aluminum trays. They are initially heated to a temperature of 180 ° C and are kept at this temperature for four minutes. They are then cooled to 10 ° C per minute to a temperature of -100 ° C before they are reheated to 140 ° C at a rate of 10 ° C per minute. The total heat of fusion is obtained from the area under the melting curve. The percent crystallinity is determined by dividing the total heat of fusion by the value of the heat of fusion for the polyethylene (292 joules per gram (J / g)).

The grafting is carried out by a procedure that begins weighing 22.7 kilograms (Kg) of dry polymer pellets in a plastic lined cardboard drum (200 liters (50 gallons)) together with a pre-weighed solution of vinyltrimethoxysilane (VTMOS) and dicumyl peroxide (DCP) in a VTMOS: DCP ratio of 18: 1. The VTMOS and DCP are commercially available from Aldrich Chemical. The amount of VTMOS added is 1.8% by weight based on the weight of the polymer. The contents of the drum are mixed in a drum for one hour to allow uniform absorption on and to the pellets. Then, the content of the container is fed little by little to a twin-screw co-rotating screw extruder Werner Pfleiderer ZSK of 30 millimeters, equipped with a high-shear mixer screw. By operating at the temperatures (in degrees centigrade (° C)) shown in Table II below and at a speed of 100 revolutions per minute (rpm), the extruder effectively mixes the contents of the container in the molten state and grafts the silane to the elastomer When using a double-stranded nozzle and a pressure of 2.07 megapascals (300 pounds per square inch), the extruded product exits the extruder at a rate of 6.8 - 9.1 Kg per hour (15 to 20 pounds per hour). The extruded product enters the water bath where it is cooled. Then, the cooled extruded product is dried with an air knife, converted into pellets and placed in a bag filled with wax. Before being placed in the bag the resulting pellets are purged with anhydrous nitrogen. If an extender oil, such as Shellflex® 371, a naphthenic oil available from Shell Chemical Company, is necessary in a composition, the contents of the container, now converted into pellets, are passed a second time through the extruder and the oil to zone two of the extruder when using a pump and injection nozzle. The operating temperatures of the extruder necessary for the incorporation of the oil are also shown in Table II. For the incorporation of the oil, the extruder operates at a speed of 250 r.p.m. to provide an output of 11.3 to 13.6 Kg per hour (25 to 30 pounds per hour). Then, the exit of the extruder is processed, as it is assumed previously so that the polymer does not contain extender oil of the chain.

Table II - Operating conditions of the extruder A main batch of curing catalyst is prepared by using 11.4 Kg of Polymer D (Table I) and sufficient dibutyltin dilaurate crosslinking catalyst (DBTDL) (Aldrich Chemical) to provide a DBTDL content of 5000 parts per million polymer ( ppm). The grafted silane polymers, prepared as described above, are dry mixed with five percent by weight, based on the weight of the polymer plus the weight of the main batch. Then, the resulting dry mix is converted into ASTM test samples by using an alternative motion screw injection molding machine (Arburg Model 370C-800-225 800 kilonewtons hydraulic clamping force (screw of 30 millimeters)). The injection molding conditions are shown in Table III below. Table III - Conditions of the injection molding machine The silane grafted injection molded test specimens are separated by a paper towel and placed in a bag or plastic bag which is filled with water, sealed and placed in a furnace operating at a set temperature of 50. ° C for two days to effect crosslinking in the test specimens. Then, the samples are separated from the bags or bags and dried with towels before being subjected to physical properties tests as follows: a)% gel (ASTM D-2765), b) Shore A hardness (ASTM D-2240) ), c) Resistance to Traction (ASTM D-638), d) Elongation (ASTM D-638), e) Abrasion of NBS (ASTM D-1630) and f) Coefficient of Friction (COF) when using a masonry tile (dry and wet) (ASTM D-1894). The results of the physical properties tests are summarized in Table V below. Table IV shows the proportions of components for injection molded and cross-linked test samples grafted with silane. The proportions of components reflect the quantities of each component without taking into account any polymer used in the main lot. The polypropylene (PP) where it is added is commercially available from Himont under the trade designation Profax® 6323.

Three comparative examples are shown in Table V together with examples 1-14 which represent the present invention. Comparative examples A, B and C have respectively the same proportions of components as examples 2, 11 and 12, but are not grafted with silane or crosslinked. Example 13 is a mixture of 50% by weight of the material of example 12 and 50% by weight of the material of comparative example C. Example 14 is a mixture of 25% by weight of the material of? - example 12 and 75% - by weight of the material of comparative example C.

Table IV Proportions of components N.D. = Not Determined The data in Table V demonstrate that the representative compositions of the present invention provide physical properties, especially Shore A hardness and COF (wet masonry tile), which are normally required for end-use applications, such as athletic footwear. and industrial. Other physical properties, such as traction and elongation are acceptable for the same applications. In contrast, Comparative Example A, prepared from the same materials and using the same proportions of the materials as Example 2, but without silane grafting and crosslinking, has a gel content of 0, a hardness value (Shore A) comparable and a similar COF value, but a notably lower NBS abrasion value. "Significantly lower" means at least 25% lower, more frequently at least 50% lower. When the test samples are prepared as described above, but with a polymer having a hardness (Shore A) before grafting and crosslinking of more than 85, the hardness values (Shore A) are increased in relation to the same polymer without grafting and crosslinking, while the NBS reaction values decrease in relation to the same polymer without grafting and crosslinking. Similar results are expected for other compositions of the present invention. It is noted that, in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it refers.

Claims (13)

1. Claims Having described the invention as above, the content of the following claims is claimed as property: 1. A non-porous, grafted and crosslinked elastomeric composition, characterized in that it comprises at least one cross-linked grafted ethylene / α-olefin interpolymer elastomer. having a hardness (Shore A) of not more than 85 and at least one crystalline olefin polymer, the crystalline olefin polymer is selected from a polypropylene homopolymer, an ethylene / α-olefin polymer having a content of ethylene of more than 85% by weight, based on the weight of the copolymer, high density polyethylene or a propylene / ethylene copolymer having an ethylene content of not more than 10% by weight, based on the weight of the copolymer, The grafted and crosslinked elastomeric composition has a hardness (Shore A) of not more than 85 and an abrasion resistance (ASTM D 1630-83, Raedor (or abrasion machine) of NBS) which is greater than that of an ungrafted elastomer composition, the ungrafted composition is prepared from the same elastomer (s) and crystalline olefin polymer (s), except that the elastomer is substantially free of grafting and crosslinking.
2. 2. A crosslinkable elastomeric composition, characterized in that it comprises at least one elastomer and grafted ethylene alpha-olefin interpolymer (EAO) having a hardness (Shore A) less than or equal to 85 and at least one crystalline olefin polymer, the polymer of Crystalline olefin is selected from a polypropylene homopolymer, an ethylene / α-olefin polymer having an ethylene content of more than 85% by weight, based on the weight of the copolymer, high density polyethylene or a propylene copolymer / ethylene having an ethylene content of not more than 10% by weight, based on the weight of the copolymer, the elastomer is grafted with a silane portion that promotes crosslinking (or crosslinking) of the grafted elastomer in the presence of moisture, the crosslinkable composition has an abrasion resistance and immediately after exposure to moisture produces a grafted, crosslinked elastomeric composition, which has a To abrasion resistance, the abrasion resistance of the crosslinked composition is greater than the abrasion resistance of the crosslinkable composition.
3. 3. The composition according to claim 1 or claim 2, characterized in that the silane portion is represented by the general formula: CH2-C- (C: -0) x (CnH2n) SiR3 in which R 'is a hydrogen atom or methyl group; x and y are 0 or 1, with the proviso that when x is 1, y is 1; n is an integer from 1 to 12 inclusive and each R is independently a hydrolyzable organic group selected from the group consisting of an alkoxy group having from 1 to 12 carbon atoms, an aralkoxy group having from 1 to 12 atoms or a lower alkyl group having from 1 to 6 carbon atoms inclusive, with the proviso that no more than two of three R groups are an alkyl group.
4. 4. The composition according to claim 3, characterized in that the silane portion is an unsaturated alkoxy silane selected from vinyl trimethoxy silane, vinyl triethoxy silane and gamma- (meth) acryloxy propyltrimethoxy silane.
5. The composition according to claim 3, characterized in that the crosslinked elastomeric composition has an abrasion resistance that is at least 25% greater than that of the ungrafted elastomeric composition or the crosslinkable composition.
6. 6. The composition according to claim 3, characterized in that the α-olefin is selected from propylene, butene, 4-methyl-1-butene, 1-hexene, 1-heptane, styrene and 1-octene.
7. The composition according to claim 3, characterized in that the ethylene / α-olefin interpolymer is selected from homogenous linear and substantially linear branched ethylene polymers with a density of 0.85 to 0.92 g / cm 3 and a flow index in the state melted from 0.01 to 500 g / 10 minutes.
8. 8. The composition according to claim 7, characterized in that the interpolymer is an ethylene / propylene / octene interpolymer.
9. 9. The composition according to claim 3, characterized in that the ethylene / α-olefin interpolymer is a -etherpolymer of ethylene, an α-olefin containing from 3 to 20 carbon atoms and a diene monomer, the monomer of diene is at least one of dicyclopentadiene, 1,4-hexadiene, 1,3-pentadiene and 5-ethylidene-2-norbonene.
10. The composition according to claim 7, characterized in that the ethylene / α-olefin interpolymer is a substantially linear ethylene polymer having an ethylene content in a range of 20 and 80% by weight inclusive and a comonomer content which may include more than one comonomer in a range of 80 to 20% by weight inclusive, the content totals 100% by weight, a melt flow index (I2) of 0.01 to 500 g / minutes, a melt flow ratio (MFR or I10 / I2) that is greater than or equal to 5.63, a molecular weight distribution (Mw / Mn) that is greater than 0 but less than 5 and a critical cutting speed at the beginning of melt fracture (OSMF) of at least 50 percent greater than the critical cutting speed at the start of melt fracture of a linear olefin polymer having a melt flow index (I2) and weight distribution molecular (Mw / Mn) similar.
11. The composition according to claim 3, characterized in that it further comprises an extender oil selected from paraffinic oils, aromatic oils, naphthenic oils, mineral oils and liquid polybutenes, the extender oil is present in an amount in a range of 1. to 150 parts by weight per 100 parts by weight of ethylene / α-olefin interpolymer elastomer and crystalline olefin polymer and optionally at least one additive selected from the group consisting of antimicrobial agents, antistatic agents, fillers and reinforcing agents selected from glass, metal carbonates, metal sulphates, talc, clays, silicas, carbon black, graphite fibers and mixtures thereof, lubricants, mold release agents, pigments, plasticizers, thermal stabilizers and ultraviolet light stabilizers , the additive (s) is (are) present in a total amount that is not more than 45% by weight based on the total weight of the composition.
12. 12. The composition according to claim 3, characterized in that the grafted and crosslinked elastomeric composition has a coefficient of friction (ASTM D-1894) measured with a wet masonry tile of at least 0.3.
13. 13. An article of non-porous manufacture, made from the grafted and crosslinked elastomeric composition according to any of claims 1-12, characterized in that it is selected from gaskets, membranes, sheets, footwear sole components, top components of footwear, shafts or axle bushes and articles for the control of wear, articles for the control of wear include articulations and sliding of drawers. SUMMARY OF THE INVENTION A crosslinkable elastomeric composition is described which includes an ethylene alpha-olefin interpolymer elastomer grafted by silane, with a hardness (Shore A) less than or equal to 85 and optionally a crystalline olefin polymer. Exposure to moisture converts the crosslinkable composition into a non-porous grafted and crosslinked elastomeric composition having a hardness (Shore A) less than or equal to 85 and an abrasion resistance that is greater than that of the crosslinkable composition. It is also greater than that of an ungrafted elastomeric composition that is prepared from the same elastomer (s) and optional crystalline olefin polymer (s) and is substantially free of grafting and crosslinking. In the articles of manufacture made from these compositions, shoe soles are included.