Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/16—Ethylene-propylene or ethylene-propylene-diene copolymers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16G—BELTS, CABLES, OR ROPES, PREDOMINANTLY USED FOR DRIVING PURPOSES; CHAINS; FITTINGS PREDOMINANTLY USED THEREFOR
  • F16G1/00—Driving-belts
  • F16G1/14—Driving-belts made of plastics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16G—BELTS, CABLES, OR ROPES, PREDOMINANTLY USED FOR DRIVING PURPOSES; CHAINS; FITTINGS PREDOMINANTLY USED THEREFOR
  • F16G5/00—V-belts, i.e. belts of tapered cross-section
  • F16G5/12—V-belts, i.e. belts of tapered cross-section made of plastics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L11/00—Hoses, i.e. flexible pipes
  • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L11/00—Hoses, i.e. flexible pipes
  • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
  • F16L11/12—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
  • C08F210/18—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers with non-conjugated dienes, e.g. EPT rubbers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S526/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S526/916—Interpolymer from at least three ethylenically unsaturated monoolefinic hydrocarbon monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S526/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S526/938—Rubbery property

Definitions

• Embodiments of the present invention generally pertain to the field of molded or extruded elastomeric vehicle brake parts and power transmission belts. More particularly, the present invention is directed to vehicle brake parts and power transmission belts utilizing elastomeric polymer compounds displaying improved processability and improved cure characteristics. These elastomeric polymers are generally of the ethylene, alpha-olefin, vinyl norbomene type. BACKGROUND
• the rubber parts must retain much of their original flexibility to insure correct function.
• the engine compartment temperature will be substantially the same in most latitudes. Accordingly, the low temperature performance specification for most automobile parts is generally fixed by the most extreme ambient conditions, while the high temperature specification has increased due to the factors mentioned above, and usually is fixed by the running temperature of the engine.
• the engine compartment temperature may reach 120° C and often may reach 140° C or even 150° C, generally when the vehicle stops after operation and no cooling is exerted from the outside air flow as would be experienced during moving operation.
• Power transmission belting transmits power or motion between V shaped sheaves.
• Such belts are used generally in 5 market segments: automotive, industrial, agricultural, fractional horse power and recreational.
• the major applications of the power transmission belt or V-belts are in the automotive area.
• the objective of the belt maker is to supply the market with a belt which will provide long service life, low maintenance, efficient operation for reliable transmission of the power, quiet operation and low cost.
• automotive belts generally are used under hood, they receive the same heat stress as the other parts previously described. In particular, the expected service life is likely to increase in the range of 10 years under more servere temperatures.
• a belt is composed most often of different materials assembled together like textile cords, fabric rubber material and the like.
• ABS anti-lock braking systems
• SBR styrene butadiene rubber
• ethylene, alpha-olefin, non-conjugated diene, elastomeric polymer compounds contain a diene monomer selected from the group consisting of 5-ethylidene-2-norbornene, 1,4-hexadiene, 1,6 octadiene, 5- methyl-1,4 hexadiene, 3,7-dimethyl-l,6-octadiene, or combinations thereof.
• the key compound (hereinafter compound will refer to an elastomeric polymer in a compounded state, that is with filler/reinforcing materials, plasticizer, curatives, accelerates, and other additives well known to those of ordinary skill, unless otherwise indicated) requirements to manufacture a good quality belt include high tensile strength and high modulus, adhesion properties to textiles and fabric, wear and abrasion resistance against the pulleys or sheaves, tear resistance, dynamic properties to work in flexion mode, environmental resistance such as ozone, U.V, high heat resistance. Such a high performing compound has to have good rheological performance and cure properties to insure consistent, economical and quality production.
• a tensile gum which is in contact with the tension fabric layed at the outer portion of the belt and the tensile cord, providing rigidity and stress resistance
• a cement compound which is around the tensile cord to provide the best adhesion between the components
• a compression component which has the V-shape and may contain short fiber to enhance its mechanical characteristics when the V-shape is obtained by a grinding technique.
• power transmission belts have generally been manufactured by using chloroprene type rubber. This material has the advantage of being processable by calendering, having good adhesion properties on the different cords and fabric, and the ability to be cured by zinc oxide to provide high mechanical properties at the temperatures today in use under the hood.
• the ethylene, alpha-olefin, non-conjugated diene, elastomeric polymer compounds are generally formulated with polymer, carbon black, process aids, curatives, and other additives known to those of ordinary skill in the art so in compounds substantially without liquid plasticizers and/or oils. Therefore the polymer has the double role of being the plasticizing agent during the processing of the compound and providing the best of its elastic properties once cured.
• the processability of a given polymer or polymer compound is also of importance in the manufacture of brake parts for consistency and general quality of production. A material which displays generally a lower viscosity at compounding and molding temperatures without the tendency to prematurely cure or scorch, would be desirable.
• a rubber compounder or fabricator of brake parts will plasticize or masticate the elastomer while adding materials such as waxes and/or reinforcing materials, antioxidants, antiozonants, curatives, accelerators, and other additives which would be well known to those of ordinary skill in the art, to produce an elastomer compound for use in brake parts.
• materials such as waxes and/or reinforcing materials, antioxidants, antiozonants, curatives, accelerators, and other additives which would be well known to those of ordinary skill in the art, to produce an elastomer compound for use in brake parts.
• plasticization, mastication, and/or compounding, or both takes place in a roll mill or an internal kneader, such as a Banbury mixer or the like.
• the materials are then fed to a device which can meter the compound (often an extruder) and force (piston of a press) the compounded elastomer into molding cavities for shaping and curing.
• Improvements in brake part manufacturing economics can be attained in many ways. Economies of scale in such a molding operation might include larger presses, and larger molds with more cavities (more parts) and/or faster cycle times. Regardless of the methods used, the processability of an elastomer compound can have a substantial impact on these economies. A lower compound viscosity could equate to more mold cavities filled faster. A faster part cure rate could lead to decreased molding cycle times, another process improvement that could also lead to economies.
• a lower compound viscosity for a given elastomeric polymer will generally be limited by the viscosity of the elastomer base of the compound during the compounding step. Further, faster, more complete cures can be adjusted, within limits, by the type of or amount of curative, and the heat transfer in the mold. However, the compounder will often have to compromise between higher levels of curative and premature scorch. Premature scorch can lead to incomplete mold cavity filling and part defects. Additionally, attempting to increase heat transfer can lead to also premature scorch, part defects and incomplete mold cavity filling.
• brake parts and/or power transmission belts made from a compound including an ethylene, alpha-olefin, vinyl norbomene elastomeric polymer will generally have improved resistance to deterioration in high temperature aging in air or polar fluids, will maintain even better low temperature performance, will resist shrinkage when exposed to heat and polar fluids compared to brake parts made from ethylene, alpha-olefin, non-conjugated dienes where the non-conjugated diene is selected from the group consisting of 5-ethylidene-2- norbomene, 1,4-hexadiene, 1,6 octadiene, 5-methyl-l,4 hexadiene, 3,7-dimethyl- 1,6-octadiene, or combinations thereof or power transmission belts made from chloroprene rubber.
• ethylene, alpha-olefin, vinyl norbomene elastomeric polymers and brake part components or power transmission belts made from compounds based on these elastomeric polymers will show lower viscosity, leading to improved compound processability, faster cure rate, and improved cure level over the ethylene, alpha-olefin, non-conjugated diene elastomer based compounds (brake parts) and chloroprene rubber compounds (belts) mentioned above.
• the vehicle brake part and/or power transmission belt will comprise an ethylene, alpha-olefin, vinyl norbomene polymer, wherein a compound made utilizing such a polymer has: a) Mooney viscosity (ML 1+4 100° C) up to 80; b) maximum cure state MH-ML (as determined by a Monsanto-Flexys oscillating disc rheometer (ODR) 2000 @ 180° C,+3°arc) of at least 140 daN.m; c) a cure rate measured in the same conditions by the ODR of at least 70 daN.m/min; d) a modulus @ 100% elongation of at least 5 MPa measured on pads cured 10 minutes @ 180° C; and e) a compression set up to 25% when measured on button cured 12 minutes @ 180° C and compressed by 25% for 22 hours at 150° C.
• Mooney viscosity ML 1+4 100° C) up to 80
• MH-ML as determined by a Mon
• Various embodiments of our invention concern certain classes of fabricated ethylene, alpha-olefin, vinyl norbomene elastomeric polymer articles and their uses. These articles have unique characteristics which make them well suited for use in certain applications. Brake parts, brake mechanisms, power tramsission belt, V- belts or toothed belts and the like made from these polymers, exhibit improved resistance to deterioration in hostile environments over brake parts, brake mechanisms, and power transmission belts based on molded and/or extruded parts made from previously available materials, such as ethylene, alpha-olefin, non- conjugated diene, elastomeric polymer's containing, for instance, 5-ethylidene-2- norbornene, 1,4-hexadiene, 1,6 octadiene, 5-methyl-l,4 hexadiene, 3,7-dimethyl- 1,6-octadiene, and the like, as well as styrene butadiene rubbers (S
• the ethylene, alpha-olefin, vinyl norbomene, elastomeric polymers of certain embodiments of the present invention on which the brake part or power transmission belt compounds are based will generally need lower levels of diene to achieve similar physical properties, when compared to brake parts made from previously available ethylene, alpha-olefin, non-conjugated diene, elastomeric polymer's based on non-conjugated dienes other than vinyl norbomene.
• the relatively low level of vinyl norbomene can lead to better heat aging, extending the temperature operating range or longer useful life of brake partsor power transmission belts based on certain embodiments of the present invention, when compared with materials previously available.
• This feature permits the use of materials such as those described in the present invention in brake parts or power transmission belts over a wide and realistic range of temperatures due to either ambient conditions (generally the low temperature requirement) or increased under the hood temperatures and for long useful part life.
• Brake parts and or power transmission belts manufactured based on the elastomeric polymers of various embodiments of the present invention will include ingredients, in addition to the elastomeric polymer or polymers, that will be well known to those of ordinary skill in the art.
• Such ingredients include but are not limited to carbon black, process aids, plasticizer, waxes, reinforcing short fibers, antioxidants, accelerators, curatives, and the like, and when some or all of such ingredients are included (mixed) in the elastomeric polymer, the mix is known as a compound.
• ethylene, alpha-olefin, diene monomer elastomeric polymer 1 Fourier Transfer Included in the brake part components contemplated by various embodiments of the present invention are cups, coupling disks, diaphragm cups, boots, tubing, sealing gaskets, parts of hydraulically or pneumatically operated apparatus, o-rings, pistons, valves, valve seats, valve guides, and other elastomeric polymer based parts or elastomeric polymers combined with other materials such as metal, plastic combination materials which will be known to those of ordinary skill in the art.
• the power transmission belts include V-belts, toothed belts with truncated ribs containing fabric faced V's, ground short fiber reinforced V's or molded gum with short fiber flocked Vs.
• the cross section of such belts and their number of ribs may vary with the final use of the belt, the type of market and the power to transmit. They also can be flat made of textile fabric reinforcement with frictioned outside faces.
• the ethylene, alpha-olefin, vinyl norbomene, elastomeric polymer component contains ethylene in the range of from 50 to 90 mole percent ethylene, preferably in the range of from 50 to 70 mole percent, more preferably in the range of from 50 to 65 mole perc 'ent,based on the total moles of the polymer
• the elastomeric polymer contains, in the range of 0.2 to 5.0 mole percent of vinyl norbomene, preferably in the range of from 0.2 to 3.0 mole percent, more preferably in the range of from 0.2 to 2.0 mole most preferably 0.2 to 0.8 percent.
• the balance of the elastomeric polymer will generally be made up of an alpha- olefin, selected from the group consisting of propylene, butene-1, hexene-1, 4- methyl-1 pentene, octene-1, decene-1, combinations thereof and the like.
• the preferred alpha-olefins are propylene, hexene-1, and octene-1.
• the alpha-olefin or alpha-olefins maybe present in the elastomeric polymer in the range of from 10 to 50 mole percent, preferable 30 to 50 mole percent, more preferably 35 to 50 mole percent.
• the elastomeric polymer will have a Mooney viscosity generally in the range of from 10 ML 1+4, 125° C, to MST 5+6, 200° C of 80 , preferably in the range of from ML 15 to MST 60, more preferably in the range of from ML 20 to MST 40.
• the elastomeric polymer will have a branching index (BI) (method of determination discussed below) generally in the range of from 0.1 to 0.7, preferably in the range of from 0.2 to 0.7, more preferably in the range of from 0.3 to 0.6.
• BI branching index
• the elastomeric polymer will have a M w GPC-LALLS ⁇ n.
• M w /M n GPC-DRI (hereinafter, M w /M n ) above 2.5, preferably above 3, more preferably above 4, most preferably above 5.
• the elastomeric polymer can be extended with an oil; aromatic, naphetenic or paraffinic, preferably paraffinic.
• the content of oil may vary from 0 % to 200%, preferably 0% to 100%, more preferably 0% to 50%.
• a combination of low and high ML polymers for optimization of elastic properties may be used.
• Carbon black used in the reinforcement of rubber generally produced from the combustion of a gas and/or a hydrocarbon feed and having a particle size from 20 nm to 100 nm for the regular furnace or channel black or from 150 to 350 nm for the thermal black.
• Level in the compound may range from 10 to 200 parts per 100 parts of elastomeric polymer (pphep).
• Processing oil preferably paraffinic
• Processing oil can be added for the power transmission belts to adjust the viscosity of the compound for good processing and the hardness in the range of 70 Shore A.
• Level in the compound may vary from 0 to 200 parts per hundred of elastomeric polymer(pphep).
• Process aids as used in such compounds can be a mixture of fatty acid ester or calcium fatty acid soap bound on a mineral filler. They are used to help the mixing of the compound and the injection of the compound into a mold. Levels range from 0.5 to 5 (pphep). • Other types of process aid can be low molecular weight polyethylene (copolymer) wax or paraffin wax. Level may range from 0.5 to 5 pphep.
• Antioxidants can be added to improve the long term heat aging, for instance a quinolein (TMQ : tri methyl hydroxyquinolein) and imidazole (ZMTI : Zincmercapto toluyl imidazole). Level ranges from 0.5 to 5 pphep.
• TMQ tri methyl hydroxyquinolein
• ZMTI Zincmercapto toluyl imidazole
• Coagents are those used to improve the peroxide cross link density by acting: either through an addition mechanism like sulfur, thiuram (TMTDS or DPPT) (0.3 pphep typically) or methacrylate (EDMA or TMPTM) or modified methacrylate (zinc diacrylate or zinc dimethacrylate) and maleimide (HVA) (0.5 to 5 pphep typically). or by transfer mechanism like the 1,2 polybutadiene or the alkyl cyanurate (TAC) (typically 0.5 to 5 pphep) and combinations thereof.
• TTTDS or DPPT 0.3 pphep typically
• EDMA or TMPTM methacrylate
• HVA maleimide
• transfer mechanism like the 1,2 polybutadiene or the alkyl cyanurate (TAC) (typically 0.5 to 5 pphep) and combinations thereof.
• Short fiber may be added in power transmission belts to improve their modulus and the belt's ability to be grinded by a rotating tool to precisely form the V- shape.
• the fiber may be cotton, polyamide, polyester or aramid or the like.
• Cotton is the most popular today in fabrication of belts. Compatibilization agent like phenolic resin or polar polyolefins might be used to enhance the cohesion between the polymer and polar short fiber. Level of fiber may be between 1 and 50 pphep, more preferably 15pphep. • Curative(s)
• peroxides are used to cure the ethylene, alpha-olefin, vinyl norbomene, elastomeric polymer and the most commonly used are the butyl peroxy benzene, butyl peroxy-hexane, dicumyl peroxide, butyl peroxy-valerate, butyl peroxy methyl-cyclohexane or combinations thereof, and the like.
• Typical quantity ranges from 1 to 5 pphep calculated on a 100 percent active base.
• a compound formulated according to the recipe below will have a: a) a Mooney viscosity ML 1+4 100° C up to 80, preferably up to 70 more preferably up to 60, most preferably up to 50; b) maximum cure state, MH-ML (ODR 180° C ⁇ 3° arc) of at least 140 daN.m, preferably at least 170 daN.m, more preferably at least 190 daN.m, most preferably at least 200 daN.m; c) a cure rate of at least 70 daN.m/min.
• the Ziegler polymerization of the pendent double bond in vinyl norbomene incorporated in the polymer backbone is believed to produce a highly branched ethylene, alpha-olefin, non-conjugated diene elastomeric polymer.
• This method of branching permits the production of ethylene, alpha-olefin, non-conjugated diene elastomeric polymers substantially free of gel which would normally be associated with cationically branched ethylene, alpha-olefin, non-conjugated diene, elastomeric polymer elastomers containing, for instance, ethylidene norbomene as the termonomer.
• the catalyst used are VOCI3 (vanadium oxytrichloride) or VCI4 (vanadium tetrachloride).
• the co-catalyst is chosen from (i) ethyl aluminum sesqui chloride (SESQUI), (ii) diethyl aluminum chloride (DEAC) and (iii) equivalent mixture of diethyl aluminum chloride and triethyl aluminum (TEAL).
• SESQUI ethyl aluminum sesqui chloride
• DEAC diethyl aluminum chloride
• TEAL triethyl aluminum
• the choice of co-catalyst influences the compositional distribution in the polymer.
• Other catalysts and co-catalysts contemplated are discussed in the two Japanese laid open patent application incorporated by reference above. The polymer with broader compositional distribution is expected to provide worse low temperature properties.
• the polymerization is carried out in a continuous stirred tank reactor at 20-65° C at a residence time of 6-15 minutes at a pressure of 7 kg/cm2.
• the concentration of vanadium to alkyl is from 1 to 4 to 1 to 10.
• 0.3 to 1.5 kg of polymer is produced per gm of catalyst fed to the reactor.
• the polymer concentration in the hexane solvent is in the range of 3 - 7% by weight.
• the resulting polymers had the following molecular characteristics:
• the intrinsic viscosity measured in decline at 135° C are in the range of 0.5 - 5.0 dl/g.
• the molecular weight distribution (M w /M n ) is greater than or equal to 2.5.
• the branching index is in the range 0.2 - 0.7.
• vinyl norbomene containing ethylene, alpha-olefin, non-conjugated diene elastomeric polymers require lower levels of peroxide to attain the same cure state compared to ethylene, alpha-olefin, non- conjugated diene elastomeric polymers with, for example, ethylidene norbomene termonomer.
• the relative degree of branching in ethylene, alpha-olefin, non-conjugated diene elastomeric polymers is determined using a branching index factor. Calculating this factor requires a series of three laboratory measurements 1 of polymer properties in solutions. These are:
• An average branching index is defined as: M v br x M w> DRi
• M w,LALLS x M v DRI M w,LALLS x M v DRI
• M v br k(IV) ⁇ a
• M V Dr viscosity average molecular weight for branched polymer
• MLR Mooney Relaxation area
• ethylene, alpha-olefin, vinyl norbomene elastomeric polymers are conducted a laboratory pilot unit (output 4 Kg/day).
• Metallocene catalysis of the above monomers is also contemplated including a compound capable of activating the Group 4 transition metal compound of the invention to an active catalyst state is used in the invention process to prepare the activated catalyst.
• Suitable activators include the ionizing noncoordinating anion precursor and alumoxane activating compounds, both well known and described in the field of metallocene catalysis.
• an active, ionic catalyst composition comprising a cation of the Group 4 transition metal compound of the invention and a noncoordinating anion result upon reaction of the Group 4 transition metal compound with the ionizing noncoordinating anion precursor.
• the activation reaction is suitable whether the anion precursor ionizes the metallocene, typically by abstraction of R] or R2, by any methods inclusive of protonation, ammonium or carbonium salt ionization, metal cation ionization or Lewis acid ionization.
• the critical feature of this activation is cationization of the Group 4 transition metal compound and its ionic stabilization by a resulting compatible, noncoordinating, or weakly coordinating (included in the term noncoordinating), anion capable of displacement by the copolymerizable monomers of the invention. See, for example, EP-A-0 277,003, EP-A-0 277,004, U.S. Patent No. 5,198,401, U.S. Patent No. 5,241,025, U.S. Patent No.
• Example 1 is a ethylene, propylene, and vinyl norbomene elastomeric polymer made ,using VOCI3 catalyst and ethylaluminum sesquichloride cocatalyst. Ethylene is present at 51.6 weight percent. Vinyl norbomene is present at 1.7 weight percent. The remainder of the terpolymer was made up of propylene. The raw polymer has a Mooney viscosity ML 1+4, 125° C of 21 and a Mooney relaxation MLR of 145, showing a high level of branching.
• Example 2 is a ethylene, propylene, and vinyl norbomene elastomeric polymer made ,using VOCI3 catalyst and ethylaluminum sesquichloride cocatalyst. Ethylene is present at 51.6 weight percent. Vinyl norbomene is present at 1.7 weight percent. The remainder of the terpolymer was made up of propylene. The raw polymer has a Mooney
• Example 2 is polymerized in substantially the same way as Example 1, except using the VCI4 as the catalyst.
• the ethylene content is 48.9 weight percent and vinyl norbomene content was approximately 1.9 weight percent.
• the remainder of the elastomeric polymer is made up of propylene.
• the elastomer has a Mooney viscosity of ML 1+4, 125° C of 20 and a Mooney relaxation (MLR) of 206. It shows an even higher level of branching compared with Example 1, generally indicative of improved processing during the compounding operation.
• Comparative Example 3 Comparative Example 3
• Comparative Example 3 is an ethylene/ propylene/ethylidene norbomene terpolymer prepared in a conventional Ziegler polymerization reaction. The product is produced in a single reactor without ammonia to promote cationic branching .
• the intention is to improve the processability by the addition of some level of branching, but not sufficient to gel the polymer.
• Branching in general plasticize the rubber and make easier the filler incorporation and the filler dispersion. It is particularly important in this application as there is substantially no oil or liquid plasticizer in the brake part compounds.
• the polymer has an ethylene content of 47.5 weight percent, ethylidene norbomene content of 5.1 weight percent, and the remainder of the elastomeric polymer is propylene.
• the Mooney viscosity ML 1+4, 125° C is 17 and the MLR is 98.
• Comparative Example 4 is polymerized to broaden the molecular weight distribution and produced a structure as described in U.S. patent 4,722,971 incorporated herein by reference for purposes of U.S. Patent practice.
• ethylene content is 48.3 weight percent
• the ethylidene norbomene content is 5.0 weight percent
• the remainder of the polymer is made up of propylene.
• the Mooney viscosity ML 1+4, 125° C is 26 and the MLR is 146.
• the polymer obtained has the same MLR as example 1, but at a higher
• Examples 5 - 9 utilized the elastomers of Examples 1 - 4 as well as a commercially available ethylene, alpha-olefin, ethylidene norbomene, elastomeric polymer (Vistalon® 2504 available from Exxon Chemical Company).
• Vistalon 2504 has an ethylene content of approximately 50 weight percent, an ENB content of approximately 4 to 5 weight percent, with the remainder being propylene.
• This product has a typical Mooney Viscosity ML 1+4,125° C of 26 and a typical MLR of 70 (See Table II). All the materials are compounded as shown in Table I.
• Table III demonstrates that at an equivalent hardness, the modulus of the vinyl norbomene polymers is generally higher than the modulii of the ethylidene norbomene containing polymers. It is a characteristic typical of a higher cure state, which is beneficial in this type of application where for example a brake cup has to hold very high pressure during the braking process.
• the tensile strength of Examples 5 and 6 are generally in the range of those examples made with ethylidene norbomene, since the average molecular weight among those polymers is very much the same.
• the elongation at break values reflect also the higher degree of cross linking for the ethylene, alpha-olefin, vinyl norbomene, elastomeric polymer.
• the air aging data show among other things that the two vinyl norbomene containing elastomeric polymers, Examples 5 and 6, generally do not loose weight after air aging. This is an important factor when considering that the brake parts often are required not to shrink during their service life, because such shrinkage could be a point of failure for a brake system Also noted is the compression set of the materials which indicates good resistance to compression set and well meeting the specification.
• the low temperature properties have been determined through the measure of the glass transition temperature of the compound by a method using the Dynamic Mechanical Thermal Analyzer (DMT A) It has measured the dynamic loss tangent of the cured rubber in a dual cantilever bending mode with a shear oscillation of 1 Hz at an amplitude of 0.62mm over a range of temperature from -70 ° C and +150° C, ramping at 2° C/minute.
• DMT A Dynamic Mechanical Thermal Analyzer
• Example 10 shows a method of polymerizing ethylene, propylene, and vinyl norbomene , using VCI4 catalyst and EASC (Ethyl Aluminium Sesqui Chloride) cocatalyst.
• Ethylene is present at 50 weight percent Vinyl norbomene is present at 2.6 weight percent.
• the remainder of the terpolymer is made up of propylene
• the polymer with 39 parts per 100 of rubber (pphep) has a Mooney viscosity ML 1+4, 125° C of 49 and a Mooney relaxation MLR of 990, showing a high level of branching.
• This ethylene, alpha-olefin, vinyl norbomene elastomeric polymer is extended by 39 parts paraffinic oil for 100 parts of rubber to ease its processing at the manufacturing and compounding stages.
• Example 11 (prospective)
• the reference elastomer used in the belt is Chloroprene polymer such as
• Neoprene®available from DuPont Co. grades GRT for the cement, GK for the tensile gum and GW for the compression gum. These polymers are vulcanized in a press for 20 minutes at 160°C using a curing system based on Zinc Oxide (5pphep), Magnesium Oxide (3 pphep) and Stearic Acid (1 pphep). The hardness is measured between 70 and 80 Shore A, with a Modulus 100% over 5 Mpa and a tensile strength over 14 Mpa.
• the replacement of the above polychloroprene by the ethylene alpha-olefin, vinyl norbomene elastomeric polymer as described in the example 1 to 4 and example 10 generally gives the same hardness, Modulus 100% and physical properties, with a considerable improvement of the retention of those properties after air aging at a temperature of 125°C or 150°C for 1000 hours.
• the ethylene alpha-olefin, vinyl norbomene elastomeric polymer will provide a substantial increase of the service life of the belt which can be estimated to 2 to 6 times more than a similar belt fabricated from the polychloroprene, depending of the technique of the fabrication of the belt.
• Power transmission belts can also be produced with other elastomeric polymers like ACSM Alkylated Chlorosulfonated polyethylene from DuPontCo. or HNBR like Hydrogenated acrylonitrile rubber from Bayer Co. Such belts will provide also a substantial increase of the expected life time at elevated temperature, but at a cost significatively higher than a similar ethylene alpha-olefin, vinyl norbomene elastomeric polymer based power transmission belt compounds.
• EPDM 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
• VNB weight % 1.7 1.9 / / /

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