WO1999011700A1

WO1999011700A1 - Curable composition having improved cured adhesion, tear resistance, cut-growth resistance, aged property retention

Info

Publication number: WO1999011700A1
Application number: PCT/US1998/018420
Authority: WO
Inventors: Robert Joseph Noel Bernier; Joseph Kestutis Valaitis
Original assignee: Union Carbide Chemicals & Plastics Technology Corporation
Priority date: 1997-09-03
Filing date: 1998-09-02
Publication date: 1999-03-11

Abstract

The present invention provides a composition comprising a granular, free-flowing ethylene-alpha olefin-diene elastomer produced in a gas phase polymerization, a metal salt of an α,β-ethylenically unsaturated carboxylic acid, a curing agent, and optionally a highly unsaturated rubber selected from the group consisting of polybutadiene, polyisoprene, polychloroprene, a styrene-butadiene rubber, polystyrene, and mixtures thereof. Preferably, the rubbers are also produced in a gas phase fluidized polymerization process using an inert particulate material.

Description

CURABLE COMPOSITION HAVING IMPROVED CURED

ADHESION, TEAR RESISTANCE, CUT-GROWTH

RESISTANCE, AGED PROPERTY RETENTION

Field of the Invention

This invention relates to curable compositions comprising a granular, free-flowing ethylene-alpha olefin-diene elastomer and an α,β-ethylenically unsaturated carboxylic acid. More particularly, the invention relates to curable compositions comprising a granular, free- flowing ethylene-alpha olefin-diene elastomer produced in the gas phase and an α.β-ethylenically unsaturated carboxylic acid of the formula (RCO)₂M which alone or in combination with other rubbers has improved cured adhesion, tear resistance, cut-growth resistance, and/or aged property retention.

Background of the Invention

There is an on-going need in the tire industry for individual tire components having a high level of cured adhesion in order to provide a tire which stands up to extended and/or extreme use conditions. In the tire industry, it is generally recognized that the higher the tear resistance and cut-growth resistance of the compounds employed in tire manufacture, the better or longer the life expectancy for the tire.

Co-agents or promoters, such as zinc diacrylates and dimethacrylates, for rubber-to-metal adhesion have been used to provide some of these advantages to sulfur-cured and peroxide-cured rubber compounds, such as with EPDMs produced in solution or bulk polymerization processes or with natural rubber, used in tires. Likewise, there is an on-going need in the roofing industry for roofing formulations having improved integrity of the membrane in order to extend the useful life of the membrane and to reduce warranty costs associated with premature failure. Further, roofing membranes can be exposed to conditions which can result in nicks and cuts from above or beneath, or experience damage due to high winds or building movement. There is a need for a roofing formulation having improved tear resistance, cut-growth resistance, resistance to penetration by sharp objects, and resistance to aging in order to extend the useful life and integrity of the roofing material. There are also similar needs and requirements for formulations used in the production of coolant hose, high pressure brake hose, and power transmission belts.

Accordingly, one or more of the aforementioned benefits are provided by the invention.

SUMMARY OF THE INVENTION

The present invention provides a composition comprising a granular, free-flowing ethylene-alpha olefm-diene elastomer produced in a gas phase polymerization, a metal salt of an α,β-ethylenically unsaturated carboxylic acid, a curing agent, and optionally a rubber selected from the group consisting of natural rubber, polybutadiene, polyisoprene, polychloroprene, a styrene-butadiene rubber, polystyrene, and mixtures thereof. Preferably, the rubbers, except for natural rubber, are also produced in a gas phase fluidized polymerization process. Detailed Description of the Invention

The present invention has utility in roofing materials, coolant hosing, high pressure brake hose, power transmission belts, automotive parts such as hosing, weather stripping, bumpers, and tire components such as sidewalls, tread, and innerliner. The present invention is particularly useful for the manufacture of pneumatic tires and their structural components to provide improved cured adhesion, improved tear resistance, improved cut-growth resistance, and/or improved aged property retention.

Ethylene-Alpha Olefin-Diene Elastomer. The ethylene- alpha olefin-diene elastomer of the composition is in granular, free- flowing particulate form with an average particle size diameter of 3mm or smaller. It is prepared by a fluidized bed process in the gas phase. Such processes are disclosed, for example, in U.S. Patent Nos. 4,994,534; 5,304,588; 5,317,036; 5,453,471; 5,585,184; and 5.616,661. Preferably, these polymerizations are conducted in a fluidized bed in the gas phase at or above the sticking or softening temperature of the final polymer product generally in the presence of inert particulate material selected from the group consisting of carbon black, silica, clay, talc, and mixtures thereof. Of the inert particulate materials, carbon black, silica, and mixtures of them are preferred. It is understood that the ethylene-alpha olefin-diene elastomer can include a blend of two or more ethylene-alpha olefin-diene polymers differing in, for example, molecular weight, amount of ethylene, amount and kind of alpha olefin, and/or amount and kind of diene, and the inert particulate material used to produce them in the gas phase. Typically, the alpha olefin contains 3 to 18 carbon atoms with 3 or 4 carbon atoms being preferred. Alpha olefins frequently used include propylene. 1-butene, and 4-methyl-l-pentene. The most preferred alpha olefin is propylene. The diene can include any of the dienes enumerated in U.S. Patent No. 5,317,036 and can include straight chain, branched chain, or cyclic hydrocarbon dienes having from about 5 to about 15 carbon atoms. Dienes which are particularly preferred include 1,4-hexadiene. dicyclopentadiene, 1,3-cyclopentadiene, 1,7-octadiene, methyloctadiene (e.g., 1 -methyl- 1,6-octadiene and 7-methyl-l,6-octadiene), ethylidene norbornene (e.g., 5-ethylidene-2-norbornene), and mixtures thereof. Of these, dicyclopentadiene, ethylidene norbornene, and methyloctadiene are most preferred.

The ethylene content of the ethylene-alpha olefin-diene is between about 40 to 85%, preferably about 50 to 80%. The alpha-olefin content is between about 13 to 60%, preferably about 20 to 50%. And, the diene content is about 0.1 to 30%, preferably about 1.5 to 15%.

The amount of ethylene-alpha olefin-diene in the composition of the invention ranges from about 8% to about 70% based upon the end use formulation, preferably about 20% to about 60%, because it depends on the product formulation. The ethylene-alpha olefin-diene of the composition has a Mooney as measured by ASTM D- 1646 ranging from about 5 to 500.

When ethylene-alpha olefin-diene is produced in the gas phase, preferably at or above the softening temperature of the polymer using inert particulate material, the product has a unique core-shell composition. In accordance with U.S. Patent No. 5,304,588, the resin particle comprises an outer shell having a mixture of inert particulate material and sticky polymer (e.g., ethylene-alpha olefin-diene) said inert particulate material being present in the outer shell in an amount higher than 75% by weight based on the weight of the outer - 0

shell, and an inner core having a mixture of said sticky polymer and the inert particulate material said sticky polymer being present in the inner core in an amount higher than 90% by weight based on the weight of the inner core.

Metal Salt of an α.β-Ethylenicallv Unsaturated Carboxylic Acid. This component of the composition of the invention has the general formula (RCO)2M, wherein R is an ethylenically unsaturated acrylic moiety having from 2 to 7 carbon atoms such as acrylic, methacrylic, cinnamic, crotonic acid moieties, and mixtures of them. Preferably, R is an acrylic acid moiety, a methacrylic acid moiety, or a mixture thereof. In the formula, M is a metal ion selected from the group consisting of sodium, potassium, magnesium, calcium, zinc, barium, aluminum, tin, zirconium, lithium, cadmium, and mixtures thereof. Preferably, M is zinc or magnesium; most preferably, M is zinc. The preferred zinc dimethacrylates and zinc diacrylates are powders and are disclosed in U.S. Patent Nos. 4,529,770 and 4,500,466. Generally, this component is formed by reacting under agitation the metal oxide and the carboxylic acid in a liquid medium, followed by drying. Alternatively, such metal salts of carboxylic acids are commercially available. Typically, the zinc dimethacrylate employed has a surface area of from about 3.0 to about 6.0 square meters per gram (m²/g) or more.

Amounts of the metal salt of an α,β-ethylenically unsaturated carboxylic acid which may be utilized in the composition of the invention depend upon the type or elastomer and/or highly unsaturated rubber employed, the type and amount of filler or mixture of fillers, and the properties desired in the cured or vulcanized composition which are dictated in part by its end-use. In general, the amount ranges from about 2.0 to 30 parts by weight per 100 parts by weight of the final rubbery polymer composition produced.

The metal salt of an α,β-ethylenically unsaturated carboxylic acid can be grafted in solution/slurry onto an ethylene-alpha olefin- diene backbone or other rubber using procedures and techniques well known to those skilled in the art or it can be added and blended in-situ during the mixing of the composition.

Curing Agents. Sulfur-containing compounds and peroxide curing agents can be used in the compositions of the invention. Curing agents for use in the invention include sulfur- containing compounds such as elemental sulfur, 4,4'- dithiodimorpholine, thiuram disulfides and thiuram polysulfides, alkylphenol disulfides, and 2-morpholino-dithiobenzothiazole; peroxides such as di-tertbutyl peroxide, tertbutylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-(tertbutylperoxy) hexane, di- (tertbutylperoxyisopropyl) benzene, tertbutyl peroxybenzoate and 1,1- di-(tertbutylperoxy)-3,3,5-trimethylcyclohexane; metal oxides such as zinc, magnesium, and lead oxides; dinitroso compounds such as p- quinone dioxime and p,p'-dibenzoylquinonedioxime: and phenol- formaldehyde resins containing hydroxymethyl or halomethyl functional groups.

Mixtures of two or more curing agents can be employed in the invention though this is generally not preferred. The suitability of any of these curing agents for use in the invention will be largely governed by the choice of elastomers, as is well known to those skilled in the compounding art. For the preferred ethylene-alpha olefin-diene polymers of the invention, the sulfur-containing compounds and the peroxides are the preferred vulcanizing agents, and the sulfur- containing compounds are most preferred.

The amount of the vulcanizing or curing agent can range from about 1 to 10 parts by weight based upon 100 parts of the ethylene- alpha olefin-diene polymer.

The vulcanizing or curing agent can optionally also be employed in conjunction with one or more accelerators. The accelerator in the composition of the invention is selected from the group consisting of a sulfenamide, a thiazole, a dithiocarbamate, a thiuram, a xanthate, a thiourea, guanidine, and mixtures thereof. Of these, sulfenamides are preferred. Sulfenamides that can be employed in the invention generally are within two classes - benzothiazolsulfenamides, including bis-benzothiazolesulfenamides as disclosed in PCT/US91/05997, and thiocarbamylsulfenamides. Benzothiazolesulfenamides can be depicted as follows:

wherein Rl, R^, and R* can be the same or different and represent hydrogen, a C3 to C9 branched, linear, or cycloalkyl group, such as, but not limited to, isopropyl, isobutyl, cycloalkenyl, tert-butyl, tert-amyl, t- octyl, as well as representing an aryl group, for example, benzyl, dibenzyl or dithiobenzyl, with the proviso that Rl and R^ cannot both be hydrogen. Preferred sulfenamides employed in the composition of the invention as an accelerator can be selected from the group consisting of 4-morpholinyl-2-benzothiazole disulfide; N-oxy diethylene- 2-benzothiazole-sulfenamide; N-cyclohexyl-2- benzothiazolesulfenamide; N-isopropyl-2-benzothiazole-sulfenamide; N-tert-butyl-2-benzothiazolesulfenamide; N,N-dicyclohexyl-2- benzothiazole-sulfenamide; N,N-diethyl-2-benzothiazole-sulfenamide; N,N-diisopropyl-2-benzothiazole-sulfenamide; and N-cycloalkylbis(2- benzothiazolsulfen)amides preferably wherein the alkyl is a linear or branched C3 to C9 and mixtures thereof. Examples of the bis(2- benzothiazole)sulfenamides can include N-cyclohexylbis(2- benzothiazole)sulfenamide; N-isopropylbis(2- benzothiazole)sulfenamide; N-tert-octylbis(2- benzothiazole)sulfenamide; N-tert-amylbis(2- benzothiazole)sulfenamide; N-isobutylbis(2-benzothiazole)sulfenamide; N-tert-butylbis(2-benzothiazole)sulfenamide; N-benzylbis(2- benzothiazole)sulfenamide; and N-dibenzylbis(2- benzothiazole)sulfenamide.

Suitable thiocarbamylsulfenamides are well known and disclosed, for example, in U.S. Patent No. 4,008,190. In general, N,N- (higher alkyl)thiocarbamylsulfenamides of the present invention have the formula

A S

II

N— C— S— B

R A

where B is selected from the group consisting of R^L

/

— N , — N , (CHR) > and — N 7 ,O

R

wherein R3 is hydrogen or the same as R^, and R^ is selected from the group consisting of alkyl radicals containing about 1 to about 4 carbon atoms, cycloalkyl radicals containing 4 to 7 carbon atoms in the ring, a phenyl radical, and an aralkyl radical or alkaryl radical containing 7 to about 12 carbon atoms; R is hydrogen or an alkyl radical containing 1 to 2 carbon atoms; x is 4 to 7; and R^ and R^ are alkyl radicals containing 6 to 30 carbon atoms. The alkyl radicals can be linear or branched and can contain primary, secondary and/or tertiary carbon atom configurations. The cycloalkyl radicals can be further substituted with alkyl radicals containing 1 to 4 carbon atoms. The thiocarbamylsulfenamide compounds contain at least 12 carbon atoms in the total of groups R5 and Εβ, and up to 60 carbon atoms.

Preferably, R^ and R^ are alkyl radical containing about 8 to about 24 carbon atoms and R^ and R^ are the same, i.e., the amine is symmetrical; and B is -NRl'R^', wherein Rl' and R^ are cycloalkyl radicals containing 5 to 7 carbon atoms in the ring. Examples of the most preferred compounds are N- oxydiethylenethiocarbamyl-N'-oxydiethylene sulfenamide, N.N-di(2- ethylhexyl)thiocarbamyl-N',N'-dicyclohexylsulfenamide, N,N- ditetradecylthiocarbamyl-N',N'-dicycloheptylsulfenamide, N,N,- dioctadecylthiocarbamyl-N',N'-dicyclohexylsulfenamide, N,N- dieicosylthiocarbamyl-N',N'-dicyclohexylsulfenamide, and mixtures thereof. Illustrative thiazoles for use in the composition of the invention can include benzothiazyl disulfide, 2-mercaptobenzothiazole, and 2.2'-mercaptobenzothiazole disulfide, zinc 2- mercaptobenzothiazole, mixtures thereof, and the like.

Illustrative dithiocarbamates for use in the composition of the invention can include Bismate® (bismuth dimethyldithiocarbamate), Butyl Eight® (activated dithiocarbamate), Amyl Cadmate® (cadmium diamyldithiocarbamate), Ethyl Cadmate® (cadmium diethyldithiocarbamate), Cumate® (copper dimethyldithiocarbamate), Amyl Ledate® (lead diamyldithiocarbamate), Methyl Ledate® (lead dimethyldithiocarbamate), Ethyl Selenac® (selenium diethyldithiocarbamate), Methyl Selenac® (selenium dimethyldithiocarbate), Ethyl Tellurac® (tellurium diethyldithiocarbamate), Amyl Zimate® (zinc diamyldithiocarbamate), Butyl Zimate® (zinc di-n-butyldithiocarbamate), Ethyl Zimate® (zinc diethyldithiocarbamate), zinc dimethyldithiocarbamate and mixtures thereof.

Illustrative thiurams for use in the composition of the invention can include Sulfads® such as dipentamethylene thiuram hexasulfide, Butyl Tuads® such as tetrabutylthiuram disulfide, Captax-Tuads Blend® (a blend of 1 part 2-mercaptobenzothiazole and 2 parts tetramethylthiuram), Ethyl Tuads® such as tetraethylthiuram disulfide, Methyl-Ethyl Tuads® (a 60:40 blend of Methyl Tuads® and ethyl tuads), Methyl Tuads® such as tetramethylthiuram, and Unads® such as tetramethylthiuram monosulfi.de, and mixtures thereof. An illustrative xanthate for use in the composition of the invention can include Propyl Zithate® such as zinc isopropyl xanthate. An illustrative thiadiazine for use as an additional accelerator herein is Nanax ΝP® (or activated thiadiazine).

Illustrative thioureas for use in the composition of the invention can include Thiate E® (trimethylthiourea), Thiate H® (1,3- diethylthiourea), and Thiate U® (1,3-dibutylthiourea), and mixtures thereof.

In the composition according to the invention, based on 100 parts by weight of ethylene-alpha olefm-diene terpolymer. the accelerator level is about 0.2 to 5.0 parts by weight, preferably 0.5 to 3.0 parts by weight. It is further understood that, when a sulfenamide is employed in the invention, one or more of the other above-mentioned accelerators can be employed as a second accelerator in a minor amount or portion (that is, less than 50% by weight of the total amount of accelerator employed in the composition, preferably less than 30%, and most preferably less than 10%.

Highly Unsaturated Rubbers. The composition of the invention can optionally include a highly unsaturated rubber selected from the group consisting of natural rubber, polybutadiene, polyisoprene, polychloroprene, a styrene-butadiene rubber, polystyrene, and mixtures thereof. In a preferred embodiment, the rubbers, except for natural rubber, are also produced in a gas phase fluidized polymerization process. Such processes are taught, for example, in U.S. Patent No. 5,453,471; WO 95/09826; and WO 95/09827. Preferably, when these highly unsaturated rubbers are produced in the gas phase, they are polymerized preferably at or above their softening or sticking temperatures in the presence of an inert particulate material selected from the group consisting of carbon black, silica, clay, talc, polymeric material, and mixtures thereof. Preferably, the inert particulate material is carbon black, silica, or a mixture thereof. When these rubbers are produced in the gas phase as described, they are granular, free-flowing and mix and compound more easily with the other ingredients of the composition as compared to rubbers produced in non-gas phase, liquid (e.g., solution and/or bulk) polymerization processes, thereby affording many downstream processing, formulation, and end-use property advantages. These gas phase produced rubbers, like the gas phase ethylene-alpha olefm- diene, have the same unique core-shell configuration as well as a catalyst metal residue (e.g., Ni, Co, or rare earth such as neodymium in amounts ranging from 10 to 35,000 ppm) throughout the resin particle.

The rubber used in the composition comprise from about 10 to 80 parts by weight based upon the weight of the total composition, preferably from about 20 to 60 parts.

Other Additives. To the composition according to the invention can be added additives usually used in the rubber industry. These additives can include, for example, one or more fillers, plasticizers, antioxidants and antiozonants, activators, tackifiers, adhesion promoters, homogenizing agents, peptizers, pigments, flame retardants, fungicides, and the like.

Fillers for use in the invention include carbon black; silicates of aluminum, magnesium, calcium, sodium, potassium and mixtures thereof; carbonates of calcium, magnesium and mixtures thereof; oxides of silicon, calcium, zinc, iron, titanium, and aluminum; sulfates of calcium, barium, and lead: alumina trihydrate: magnesium hydroxide; phenol-formaldehyde, polystyrene, and poly(alphamethyl)styrene resins; natural and synthetic fibers: and the like.

Plasticizers for use in the invention include petroleum oils such as ASTM D2226 aromatic, naphthenic and paraffinic oils: polyalkylbenzene oils; organic acid monoesters such as alkyl and alkoxyalkyl oleates and stearates; organic acid diesters such as dialkyl, dialkoxyalkyl, and alkyl aryl phthalates, terephthalates, sebacates, adipates, and glutarates; glycol diesters such as tri-, tetra-. and polyethylene glycol dialkanoates; trialkyl trimellitates; trialkyl, trialkoxyalkyl, alkyl diaryl, and triaryl phosphates; chlorinated paraffin oils; coumarone-indene resins; pine tars; vegetable oils such as castor, tall, rapeseed, and soybean oils and esters and epoxidized derivatives thereof; and the like.

Antioxidants and antiozonants for use in the invention include hindered phenols, bisphenols, and thiobisphenols; substituted hydro quinone s ; tris (alky lp henyl)p hosp hite s ; dialky lthiodip roprionate s ; phenylnaphthylamines; substituted diphenylamines; dialkyl, alkyl aryl, and diaryl substituted p-phenylene diamines: monomeric and polymeric dihydroquinolines; 2-(4-hydroxy-3,5-t-butylaniline)-4,6- bis(octylthio)-l,3,5-triazine, hexahydro-l,3,5-tris-β-(3,5-di-t-butyl-4- hydroxyphenyl)propionyl-s-triazine, 2,4,6-tris(n-l,4-dimethylpentyl-p- phenylenediamino)-l,3,5-triazine, tris-(3,5-di-t-butyl-4-hydroxy- benzyl)isocyanurate, nickel dibutyldithiocarbamate, 2-mercap- totolylimidazole and its zinc salt, petroleum waxes, and the like.

Other additives for use in the invention include activators (metal oxides such as zinc, calcium, magnesium, cadmium, and lead oxides; fatty acids such as stearic, lauric, oleic, behenic, and palmitic acids and zinc, copper, cadmium, and lead salts thereof; di-. tri-, and polyethylene glycols; and triethanolamine). Tackifiers (rosins and rosin acids, hydrocarbon resins, aromatic indene resins, phenolic methylene donor resins, phenolic thermosetting resins, resorcenol- formaldehyde resins, and alkyl phenol formaldehyde resins such as octyl-phenol-formaldehyde resin), homogenizing agents, peptizers, pigments, flame retardants, fungicides, and the like can also be employed in the composition of the invention.

The total amount of additives can range from about 20 to 900 parts by weight based upon 100 parts of the elastomers in the composition. In general, the amount of filler ranges from about 1 to 500 parts by weight of the polymer composition; the amount of cure activators ranges from about 0.1 to 10 phr; the amount of antioxidants and antiozonants and stabilizers ranges from about 0.1 to 10 phr; the amount of softeners and tackifiers ranges from about 0.1 to 30 phr; the amount of processing oils or plasticizers ranges from about 1 to 200 phr; and the amount of homogenizing agents, peptizers, pigment, flame retardants, fungicides and the like ranges from about 1 to 200 phr.

Also, the composition can optionally contain an adhesion promoter. Illustrative adhesion promoters can include such resins as phenolic methylene donor resins, phenolic thermosetting resins, and resorcenol-formaldehyde resins. A number of the phenolic, rosin acid, and especially alkyl phenol formaldehyde resins can act both as a tackifier as well as cured adhesion promoter. Of these, octyl-phenol- formaldehyde resin is most preferred for its dual function of improved cured adhesion and tack. Forming the Composition. The mixing or blending of ingredients forming the composition according to the invention is performed by means well known to those skilled in the art. Such means can include, for example, a two-roll mill, Banbury® mixer, Henschel® mixer, extruder, or the like, in the usual manner.

Typically, the composition containing ethylene-alpha olefin-diene, e.g., EPDM, metal salt of an α,β-ethylenically unsaturated carboxylic acid, additional rubbers, other optional additives, and curing agent alone or in combination with an accelerator is mixed in two stages. Generally, all of the ingredients, except the accelerator and sulfur ("cure package"), are added in a first stage (often referred as the "masterbatch" stage). In a second stage, the curing agent (e.g., sulfur) and the accelerator or blend of accelerators are added to the masterbatch. This second stage is often referred to as the "final" stage. Alternatively, the accelerators can be incorporated in the masterbatch, or in single stage mixing. The ingredients are mixed at a temperature and time to obtain uniform mixing.

Curing temperatures and time are generally not critical and cure temperatures can range from about 250°F (121°C) to about 400°F (204°C) and cure times range from about 0.5 minutes to about 3 hours. Independent of the method of mixing the composition, the method of curing may be chosen from the many conventionally known methods including open steam, autoclave, press or mold curing, liquid salt bath, hot air, microwave, UHF or infrared vulcanization. The method of forming an article into a desired shape is largely dependent upon the mixing and curing method chosen and known to those skilled in the forming art. Some representative methods are mold forming, extrusion, roller head die forming, die cutting, hand lay-up. The elastomeric composition of the present invention can be employed in the production of elastomeric articles such as tire sidewalls, roofing membranes, as well as, other molded and extruded articles. And, in the case of tires, belts and hoses, these milling, molding and/or extruding methods are used at some point in the method of manufacturing.

Applications. The basic formulation performance requirements for any application are heavily dependent on the polymer used. However, the formulation can be enhanced significantly by the fillers, plasticizers, modifiers, and cure systems used. Formulations for the various applications vary in their constituents according to the necessary performance requirements.

Some of the applications are intended for relatively static in-use conditions such as coolant hose and roofing membrane. Other applications encounter dynamic in-service conditions such as tire sidewall and brake hose and power transmission belt.

These rubber components are exposed to different degrees of heat, ozone, UN, water, and petroleum derivatives. Aged property retention is beneficial in all applications. It is also important that all applications have good cut, chip, and tear resistance. Since conditions in which these applications are employed can differ, component in- service conditions thus dictate the formulation development for specific performance requirements.

Tire Sidewalls. When ΝR/BR is the polymer system, it requires high levels of antioxidants, antiozonants, and microcrystalline waxes to protect it from the environment. When EPDM is used, these protective materials are not necessary because of the inherent stability of EPDM.

Properties critical to the performance of tire sidewalls are dynamic ozone and flex resistance for the service life of the tire. It is also essential that the sidewall compound have good adhesion to the adjacent components (e.g., carcass and tread).

When NR/BR is used as the rubber in this application, the required protective materials function by migrating to the surface of the tire sidewall and cause discoloration and staining. The use of EPDM does not require the protective materials; and, thus, the unattractive sidewall appearance is not a problem. In fact EPDM gives the tire sidewall a naturally appealing black sheen appearance.

The benefits of using metal salts of α, β-ethylenically unsaturated carboxylic acid compounds in the EPDM formulation in which the EPDM is produced by a gas phase process include the following: enhanced cured adhesion to adjacent components; improved aged property retention; increased tear and cut-growth resistance; improved ozone and UN resistance; and improved flex fatigue.

Roofing Membrane. It is well known that EPDM has excellent long term weathering performance properties and is the reason why it is used for this application.

Usually EPDM roofing membranes carry a long term performance warranty; and, thus, formulation modifications which further improve the in-service life of the membrane are cost effective. The use of zinc dimethacrylate and related compounds has shown large improvements in aged property retention and especially aged tear and cut-growth resistance. The geometry of the tear path has been modified so that even when tear is initiated, at the higher required force, the damage is minimized because the tear path reverses on itself.

Coolant Hose. Coolant hose compounds have to have good heat resistance, compression set, coolant, and oxidative resistance. Zinc dimethacrylate and the related compounds, when incorporated into the hose formulation, show improvements in all of these properties; and, thus, extend the useful life of the automotive coolant hose.

High Pressure Brake Hose. Such properties as high temperature resistance, good ozone resistance, good flex fatigue, and good water and brake fluid resistance are critical for this application. The use of zinc dimethacrylate and the related compounds show improvements in all of these properties; and, thus, have extended the useful life of this automotive component.

Power Transmission Belt. Heat, cut-growth, and ozone resistance are critical requirements in this application. The use of metal salts of α, β-ethylenically unsaturated acid compounds results in the improvement of the required performance characteristics.

All references cited herein are incorporated by reference.

Whereas the scope of the invention is set forth in the appended claims, the following examples illustrate certain aspects of the present invention. The examples are set forth for illustration only and are not to be construed as limitations on the invention, except as set forth in the claims. All parts and percentages are by weight unless otherwise specified. EXAMPLES Mixing Procedures. Mixing of the subject compounds was done in a two stage process; in the first stage (masterbatch stage) all of the ingredients were added except the cure system, in the second stage (final stage) the cure system was added and the compound was then ready for sheeting and curing. The mixture may also be done as a one stage process where all of the materials are incorporated in a single stage as is obvious to those knowledgeable in this art.

First Stage (Masterbatch) Mixing Procedure For the Tire Formulations. The masterbatch was mixed in a laboratory "B" size (approximately 1685 cc mixing cavity volume) Banbury® at 77 revolutions per minute rotor speed. The Banbury® was preheated to 120°F and the masterbatch ingredients were loaded in the following sequence: one half of the polymer; all of the remaining masterbatch materials such as oil, zinc oxide, stearic acid, zinc stearate. resin and zinc dimethacrylate or zinc diacrylate; and finally the remaining polymer. These materials were then mixed for 1.0 minute. After one minute mixing, all of the carbon black was added and the masterbatch continued to be mixed for a total accumulated time of 3.0 minutes. At the three minute time, the ram was raised and swept down. The ram was lowered again and mixing was continued for a total mixing time of 4.5 minutes, during which time the Banbury® temperature rises to 300° to 320°F. The batch was dumped, sheeted to an approximate thickness of 0.5 inch on a 120°F, two roll mill (6 inch diameter, 12 inch width) and allowed to cool to room temperature prior to the second stage addition of the cure system. First Stage (Masterbatch) Mixing Procedure For the Roofing Formulations. With the laboratory "B" size Banbury® at 120°F, all of the masterbatch ingredients were loaded in the following order: one half carbon black and clay, one half of the polymer, zinc oxide, stearic acid, processing oil, zinc dimethacrylate, second half of the polymer, and remaining carbon black and clay. The masterbatch was then mixed for 1.5 minutes. The batch was dumped with the temperature between 290° to 300°F. The batch was sheeted on a 120°F two roll mill to an approximate thickness of 0.5 inches and allowed to cool to room temperature prior to the second stage addition of the curatives.

Second Stage (Final) Mixing Procedure For the Tire and Roofing Formulations. The two roll, laboratory size (6 inch diameter, 12 inch width) mill was preheated to 120°F. The masterbatch was added to the mill and milled until banding on the mill was consistently good (about one minute). Sulfur was added and three cross-cuts were made on each side, followed by two end-roll passes. The accelerator, or accelerator blend, or peroxide and co-agents were then added followed by five cross-cuts each side and two end-roll passes. The final formulation was allowed to cool to room temperature prior to the preparation of test specimens.

Tire Sidewall Compound Improvement. Tables 1 (Formulations) and 2 (Properties) illustrate the benefits of using α,β-ethylenically unsaturated carboxylic acid compounds (zinc dimethacrylate and zinc diacrylate and others) in a 100% EPDM tire sidewall formulation. Performance property improvements are evident at all levels of zinc dimethacrylate (4 to 20 phr) and zinc diacrylate (10 phr) tested. The benefits evident and shown in Table 2 include the following: Enhanced cured adhesion values by as much as 80%; Improved aged property retention (stress-strain and hardness) by as much as 20%; Increased Die C tear resistance by as much as 65%; Improved cut-growth resistance by as much as three orders of magnitude or higher.

As those familiar with the performance of tire materials know, these type of performance improvements will result in tires with improved durability and extend the useful life of tires built with these materials.

Rubber Roofing Compound Improvements. Tables 3 (Formulations) and 4 (Properties) illustrate performance property improvements at all levels (2 to 12 phr) of zinc dimethacrylate used in these evaluations. The benefits shown in Table 4 include the following; Improved aged property retention (stress-strain and hardness) by as much as 50%; Improved Die C tear strength by as much as 37%; Improved normal trouser tear strength by as much as 183%: Improved aged trouser tear retention by as much as 1,573%. Not only is the magnitude of the trouser tear force increased, but the direction of the tear propagation path is reversed. The tear damage that would thus be incurred with this type of roofing membrane would be limited in that the tear path would turn back on itself rather than propagate along the length of the roof.

As those familiar with the performance of roofing membrane materials know, these failure and aged property retention improvements will result in increased useful life of the membrane and reduced costs associated with warranties. TABLE 1: FORMULATIONS

Sample No. 2 3 4 5 10

MASTERBATCH STAGE Elastoflo™ MEGA 4246* 120.0 120.0 120.0 120.0 120.0 120.0 120.0 120.0 120.0 120.0

N 660 Carbon Black 30.0 26.0 22.0 30.0 30.0 30.0 30.0 30.0 20.0 30.0

Naphtenic Oil 10.0 10.0 10.0 4.0 6.0 4.0 4.0 4.0 4.0

Zinc Oxide 4.0 4.0 4.0 4.0 4.0 4.0 ... ... ... 4.0

Stearic Acid 1.0 1.0 1.0 1.0 1.0 4.0 — ... ... 4.0

Zinc Stearate ... ... ... ... ... ... 5.0 5.0 ... ...

Octyl Phenol Formaldehyde Resin 4.0 4.0 ... ... 6.0 8.0 8.0 8.0 8.0 8.0

Zinc Dimethacrylate ... 4.0 8.0 10.0 6.0 10.0 10.0 10.0 20.0 —

Zinc Diacrylate 10.0

Masterbatch Total 169.0 169.0 165.0 169.0 173.0 180.0 177.0 177.0 168.0 180.0

FINAL STAGE Insoluble Sulfur 1.0 1.0 1.0 1.0 1.4 2.0 3.0 ... 2.0

N-t-Butyl-2-Benzothiazyl Disulfide 2.3 2.3 2.3 2.3 2.3 2.3 ... 2.3 Tetramethylthiuram Disulfide 0.2 0.2 0.2 0.2 ... — ... 0.1 Dithiodimorpholine 2.5 2-(Morpholinodithio)-Benzothiazole 1.5 ... N,N'-m-Phenylenedimeleimide 1.5 Dicumyl Peroxide (40%) 4.0 ... Benzothiazyl Disulfide 0.2 ... Final Stage Total 172.5 172.5 168.5 172.5 176.7 184.3 181.3 181.5 173.7 184

Contains 20 phr carbon black per 100 parts EPDM polymer. Comparative example.

D-17453

23

TABLE 2: FORMULATION PROPERTIES Sample No. 1** 2 3 4 5 6 7 8 9 10

Cured Adhesion - ASTM

D413

Average, lb. /in. 51.1 29.0 71.5 64.1 48.7 70.8 73.0 92.9 63.5 65.0

Peak, lb ./in. 52.3 30.0 82.4 66.0 50.6 72.1 74.6 94.4 64.2 70.0

Failure Mode Int.Fac Off. Fa Fab.Fa Fab.Fai Off.Fab Int.Fac Int.Fac Int.Face Int.Face Off.Fa e b. il 1 e e b.

(0 c

CD Stress-Strain Properties, <Λ

H Normal ASTM D 412,

H Aged ASTM D 573

H m 300% Modulus, psi 1090 640 600 820 1096 1126 932 891 2111 964

0) Tensile, psi. 2967 2480 2280 1760 2611 2307 1731 2520 3067 1882 x m Aged Retention, 89 103 88 99 94 95 109 88 102 107 m %

Elongation, % 534 740 820 750 688 681 725 702 501 732

31

C Aged Retention, 72 84 87 88 69 66 83 67 84 88 m %

Shore "A" Hardness, ASTM σσ>> D412

Normal 77 76 79 84 8 833 8 877 8 855 8 855 8 833 87

Aged 81 82 82 85 8 877 8 888 8 888 8 877 8 866 87

Change + 4 1 3 2 3

Die C Tear, ASTM D 625 lb./in. 234 276 263 263 299 292 284 296 299 284

TABLE 3: ROOFING FORMULATIONS*

Sample No. 1 2 3 4 5

Elastoflo™ MEGA 7315 20.0** 120.0** 120.0** 120.0** 120.0**

N 330 Carbon Black 20.0 20.0 20.0 20.0 20.0

N 650 Carbon Black 70.0 70.0 70.0 70.0 70.0

Clay 40.0 40.0 40.0 40.0 40.0

Zinc Oxide 3.0 3.0 3.0 3.0 3.0

Stearic Acid 1.0 1.0 1.0 1.0 1.0

Paraffϊnic Oil 80.0 78.0 76.0 72.0 68.0

Zinc Dimethacrylate 0.0 2.0 4.0 8.0 12.0

Masterbatch Total 334.0 334.0 334.0 334.0 334.0

Final Stage

Sulfur 1.0 1.0 1.0 1.0 1.0

Tetramethylthiuram Disulfide 0.5 0.5 0.5 0.5 0.5

N-t-Butyl-2-Bensothiazyl Disulfide 2.8 2.8 2.8 2.8 2.8

Final Stage Total 383.3 383.3 383.3 383.3 383.3

* Test stopped at 3,000 cycles. ** Comparative example.

TABLE 4: ROOFING FORMULATIONS PROPERTIES

Sample No. I **

Rheometer at 320F, ASTM D 2084 Torque, lb./in.: Minimum 9.31 7.41 9.37 10.44 12.81 Maximum 27.59 37.54 27.59 23.37 30.61 Ts, Min. 2.50 4.17 2.58 2.67 3.42 Tso, Min. 3.58 5.83 3.67 5.00 6.17 Too, Min. 88..2255 1188..9922 88..2233 1155..5500 1188..8833

Streess-Strain Properties, Normal ASTM D 412, Aged ASTM D 573 200% Modulus, psi. 754 625 470 428 659 Tensile, psi. 1961 1990 1431 1181 1206

Aged Retention, % 100.7 96.7 126.3 126.8 141.8 Elongation, % 495 605 718 718 568

Aged Retention, % 49.2 44.6 56.1 62.0 60.2

Shore "A" Hardness, Normal 65.8 68.0 66.8 67.8 72.6

Aged 75.8 74.6 74.0 73.0 87.8 Change 10.0 6.6 7.2 5.2 5.2

Die C Tear, ASTM D 625, lb./in. 171.2 193.0 234.9 223.8 222.7

Trouser Tear, ASTM D 470 Modified ** Comparative example.

TABLE 4: ROOFING FORMULATIONS PROPERTIES

(CONTINUED)

Sample No. 1" 2 3 4 5

Average Normal, lb./in. 95.6 115.8 185.2 135.9 271.1

Aged, lb./in. 13.1 60.8 122.5 199.0 87.6

Retention, % 13.7 52.5 66.1 146.4 141.8 Peak Normal, lb./in. 121.8 146.3 224.9 222.2 420.3

Aged, lb./in. 1133..66 6655..33 113300..88 221144..00 9911..88

Retention, % 11.2 44.6 58.2 96.3 21.8

**Comparative example.

TABLE 5: ZDM OTHER GAS PHASE EPDM FORMULATIONS

Roofing Coolant Brake Trans.

Ingredients Tire SW Membrane Hose Hose Belt Elastoflo™ MEGA 4246 120.0 120.0 120.0 120.0 120.0

N 650 CB — 70.0 100.0 — —

N 660 CB 30.0 — -- -- --

N 330 CB — 20.0 -- -. —

N 762 CB — -- 95.0 — .-

N 774 CB — — — 70.0 --

Whiting - - 40.0 — 40.0

Clay — 40.0 — 30.0 30.0

Naphthenic Oil 6.0 - - - —

Paraffinic Oil -- 80.0 140.0 15.0 5.0

Zinc Oxide 4.0 3.0 3.0 5.0 5.0

Stearic Acid 1.0 1.0 1.0 1.0 1.0

Octyl-Phenol-Formaldehyde Resin 6.0 - - — 6.0

ZDM 6.0 8.0 12.0 10.0 10.0

MB Total 173.0 342.0 511.0 251.0 217.C

Sulfur 1.0 1.0 0.5 1.0 1.0

N-T-Butyl-2-Benzothiazole 2.3 2.8 - 2.8 2.3

Sulfenamide

TABLE 5: ZDM OTHER GAS PHASE EPDM FORMULATIONS

(CONTINUED)

Roofing Coolant Brake Trans.

Ingredients Tire SW Membrane Hose Hose Belt

Tetramethyl Thiuram Disulfide 0.5 3.0 0.5 4,4'-Dithio Dimorpholine 2.0 Zinc Dibutyldithiocarbamate 2.0 Zinc Dimethyldthiocarbamate 2.0

Total 176.3 346.3 520.5 255.3 220.3

Claims

What is claimed is:

1. A composition comprising an ethylene-alpha olefin- diene produced by a gas phase polymerization, a metal salt of an ╬▒,╬▓- ethylenically unsaturated carboxylic acid, a curing agent, and optionally a highly unsaturated rubber.

2. The composition of Claim 1 wherein the metal salt of an ╬▒, ╬▓-ethylenically unsaturated carboxylic acid has the formula (RCO)₂M, wherein R is an ethvlenically unsaturated acrylic moiety having 2 to 7 carbon atoms, M is a metal ion selected from the group consisting of sodium, potassium, magnesium, calcium, zinc, barium, aluminum, tin, zirconium, lithium, cadmium, and mixtures thereof; the ethylene-alpha olefin-diene contains an alpha olefin is selected from the group consisting of propylene, 1-butene, and 4- methyl-1-pentene; and the diene is selected from the group consisting of 1,4-hexadiene, dicyclopentadiene, 1,3-cyclopentadiene, 1,7-octadiene, methyloctadiene, ethylidene norbornene, and mixtures thereof; wherein the curing agent is selected from the group consisting of a sulfur-containing compound a peroxide, a metal oxide, a dinitroso compound, and mixtures thereof; and the highly unsaturated rubber is selected from the group consisting of natural rubber, polybutadiene, polyisoprene, polychloroprene, styrene-butadiene polymer, polystyrene, and mixtures thereof.

3. The composition of Claim 2 wherein the ethylene- alpha olefin-diene and the highly unsaturated rubber are both produced in a gas phase fluidized bed polymerization in the presence of at least one inert particulate material selected from the group consisting of carbon black, silica, clay, talc, polymeric materials, and mixtures thereof.

4. The composition of Claim 3 wherein the ethylene- alpha olefin-diene is ethylene-propylene-5-ethylidene-2-norbornene or ethylene-propylene-methyloctadiene; wherein the metal salt of an ╬▒,╬▓- ethylenically unsaturated carboxylic acid is a zinc dimethacrylate, a zinc diacrylate, or a mixture thereof; and wherein the highly unsaturated rubber is selected from the group consisting of polybutadiene, poly (styrene-butadiene), and polyisoprene.

5. The composition of Claim 1 wherein additives selected from the group consisting of fillers, plasticizers, antioxidants, antiozonants, activators, accelerators, tackifiers, homogenizing agents, peptizers, pigments, flame retardants, and fungicides are employed.

6. The composition of Claim 5 wherein the curing agent is a sulfur-containing compound, a peroxide, or a mixture thereof optionally employed in combination with an accelerator selected from the group consisting of a sulfenamide, a thiazole, a dithiocarbamate, a thiuram, a xanthate, a thiourea, a guanidine, and mixtures thereof.

7. An elastomeric article prepared by shaping and vulcanizing the composition of Claim 1.

8. The elastomeric article of Claim 8, which article is selected from the group consisting of a tire sidewall, hosing, belt, and a roofing membrane.

9. The use of the composition of Claim 1 in a tire, a roofing membrane, a coolant hose, a high pressure brake hose, and a power transmission belt.

10. The use of a metal salt of an ╬▒-╬▓ ethylenically unsaturated carboxylic acid and an ethylene-╬▒-olefin-diene produced in the gas phase to improve cut growth resistance, cured adhesion, tear resistance, and/or aged property retention.