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
  • C08L23/10—Homopolymers or copolymers of propene
• • 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
  • C08L23/10—Homopolymers or copolymers of propene
  • C08L23/12—Polypropene
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/08—Polymer mixtures characterised by other features containing additives to improve the compatibility between two polymers
• • 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
  • C08L23/10—Homopolymers or copolymers of propene
  • C08L23/14—Copolymers of propene
  • C08L23/142—Copolymers of propene at least partially crystalline copolymers of propene with other olefins

Definitions

• This invention relates to at least partially cross-linked olefin thermoplastic elastomers containing at least one polymer derived from a metallocene production process.
• Olefin thermoplastic elastomers have been widely used, particularly as substitutes for vulcanized rubbers, and more particularly in the field of molded products. These cross-linked olefin thermoplastic elastomers possess exceptional properties, including tensile strength, elongation at break, elastomeric properties, and heat resistance. Historically, many of the elastomers of the type identified above, have been constructed of polymers made from a Ziegler-Natta catalyzed reaction. However, as described in U.S. Patent No. 5,198,401 , herein incorporated by reference, and International Application No.
• the polymerization of olefins, diolefins and acetylenically unsaturated monomers to homopolymers and copolymers in the presence of an ionic metallocene catalyst is now producing unique materials.
• the polypropylene polymers obtained via the metallocene catalysis process are generally at least substantially isotactic and often fully isotactic.
• low ethylene content EPR's are being produced. Specifically, the reactions are performed in the presence of a metallocene catalyst of the general formula
• Cp is a cyclopentadienyl ring or a derivative thereof;
• M is a Group IV, V or VI transition metal;
• R is a hydrocarbyl group or hydrocarboxyl group having from 1 to 20 carbon atoms;
• X is a halogen and, m equals 1 to 3; n equals 0 to 3; Q equals 0 to 3, and the sum of m + n + q is equal to the oxidation strength of the transition metal.
• Further examples of metallocenes catalysts and processes are provided for in U.S. Patent Nos. 4,530,914; 4,871 ,705; 4,937,299; 5,124,418; 5,017,714; 5,120,867; 5,278,119;
• thermoplastic elastomers TPEs
• the compositions of this invention comprise a cross- linked or at least partially cross-linked thermoplastic elastomeric composition formed of from 10 to 90 percent of a first polymeric material comprised of ethylene, ⁇ -olefin and optionally a non-conjugated diene, and 90 to 10 percent of a second olefin polymeric material, wherein at least one of the first or second polymeric materials is at least partially the product of a metallocene polymerization reaction.
• the first or second polymeric material can be comprised of a blend of two or more polymers provided at least one is a metallocene polymer.
• the first polymeric material is an elastomer of ethylene-propylene-diene-polymethylene, i.e., an EPDM.
• EPDM is intended to reflect a terpolymer of ethylene, propylene and a non-conjugated diene.
• the copolymer is an elastomer of ethylene and propylene, referred to sometimes as EPR and sometimes as EP(D)M-wherein the diene is optional.
• the EP(D)M rubber has an ethylene content of less than 40 percent. More preferably, the EP(D)M rubber will have an ethylene content of less than 20 percent by weight. However, it is believed that metallocene EP(D)M may have certain advantages even with a C 2 above 40 percent.
• thermoplastic phase of the invention include thermoplastic crystalline polyolefin, homopolymers and copolymers. They are desirably prepared from monolefin monomers having three to six carbon atoms such as propylene, 1-butene, isobutylene, 1-pentene and the like, with polypropylene being preferred.
• the second olefin polymeric material is polypropylene.
• the polypropylene is a metallocene derived polypropylene.
• a third-or more-polymeric material is added to the composition.
• Fig. 1 provides a graphical comparison of melt flow rate versus toughness at 23°C of TPE compounds in accord with the present invention
• Fig. 2 is a graphical representation of the comparison of melt flow rate versus ACR viscosity at 200°C;
• Fig. 3 is a graphical comparison of stress-strain for Ziegler-Natta polypropylene versus metallocene polypropylene at various melt flow rates
• Fig. 4 is a graphical comparison of the spiral flow of DVA's based on polypropylene type at 20 and 30 MFR;
• Fig. 5 is a graphical comparison of the spiral flow of DVA's based on polypropylene type at .7 and 5 MFR.
• DETAILED DESCRIPTION OF THE INVENTION Reference will now be made in detail to the present preferred forms of the invention. While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention defined by the appended claims.
• This invention is particularly directed to an elastomer phase such as metallocene ethylene, alpha-olefin (diene) polymethylene rubber e.g. ethylene-propylene (diene) polymethylene rubbers EP(D)M and/or a thermoplastic phase such as metallocene polypropylene.
• elastomer phase such as metallocene ethylene, alpha-olefin (diene) polymethylene rubber e.g. ethylene-propylene (diene) polymethylene rubbers EP(D)M and/or a thermoplastic phase such as metallocene polypropylene.
• ethylene-olefin (diene) polymethylene rubber e.g. ethylene-propylene (diene) polymethylene rubbers EP(D)M
• a thermoplastic phase such as metallocene polypropylene.
• propylene is the most common alpha-olefin in the representative elastomer
• other monomers such as butene-1 ,
• the invention is directed to the use of EP(D)M rubber as the elastomer component and polypropylene as the plastic component of a dynamically vulcanized alloy (DVA) composition-one of the components being the product of metallocene catalysis.
• DVA dynamically vulcanized alloy
• metallocene EP(D)Ms used in dynamically vulcanized alloys increase toughness by a factor of at least two.
• the dynamically vulcanized alloys of the present invention include, for example, cured blends of EP(D)M with thermoplastic crystalline polyolefins, homopolymers or copolymers.
• the invention is directed to the unexpected finding that EP(D)M polymers made by metallocene catalyst having an ethylene content from 10 to 40 percent by weight are excellent elastomers for use in dynamically vulcanized alloys.
• EP(D)M polymers having a low ethylene content provide particularly excellent properties in a DVA even at relatively low Mooney viscosities and (ii) provide a lower viscosity versus shear rate.
• EP(D)Ms having a C 2 level below 40 percent provide equivalent or improved physical properties in a DVA as compared to conventional EP(D)Ms, but at a lower cost.
• the particular EP(D)Ms which are the focus of the present invention are those prepared via a metallocene catalysis (M) process which is the preferred process for producing these low ethylene polymers.
• EP(D)Ms made by today's Ziegler-Natta catalysts (Z) do not polymerize low C 2 content polymers.
• improvements in DVA's have also been achieved using a combination of Ziegler-Natta and metallocene EP(D)Ms.
• the terpolymer will be used, i.e. EPDM.
• Suitable non-conjugated dienes include 5-ethylidene-2- norbornene(ENB); 1 , 4-hexadiene; 5-methylene-2-norbomene(MNB); 1 ,6- octadiene; 5-methyl-1 ,4-hexadiene; 3,7-dimethyl-1 , 6-octadiene; 1 ,3- cyclopentadiene; 1 ,4-cyclohexadiene; vinyl norbornene (VNB); dicyclopendadiene (DCPD).
• ENB 5-ethylidene-2- norbornene
• MNB 5-methylene-2-norbomene
• VNB vinyl norbornene
• DCPD dicyclopendadiene
• thermoplastic olefin polymer/copolymer thermoplastics can be significantly improved when the thermoplastic olefin polymer/copolymer is prepared via a metallocene catalysis process.
• polypropylene is used.
• fractional MFR high molecular weight polypropylene
• polypropylene includes homopolymers of propylene as well as reactor copolymers of polypropylene which can contain about 1 to 20 percent by weight of ethylene or an ⁇ -olefin comonomer of 4 to 16 carbon atoms, and mixtures thereof. Furthermore, it is believed that the use of a combination of metallocene polypropylene and Ziegler-Natta polypropylene also allows for the formation of superior DVA's.
• the DVAs are comprised of a metallocene polyolefin thermoplastic, particularly polypropylene, and a metallocene EP(D)M, or blends of these with Ziegler-Natta thermoplastics and/or elastomers.
• the DVA's of the present invention are preferably formed via melt blending in the presence of rubber curatives in a high shear device at an elevated temperature (e.g. 180°C).
• the onset of dynamic vulcanization is accompanied by a rapid increase in mixing torque and an increase in temperature.
• Morphology typical of these DVAs prepared by dynamic vulcanization generally consists of a discontinuous array of rounded and irregular shaped rubber particles ranging in size from 0.2 - 5 ⁇ m in a continuous polyolefin matrix.
• a co-continuous state or a phase inversion is also possible depending on the amount of rubber (e.g. EPDM) relative to the plastic (e.g. polypropylene), and the cure system or degree of cure of the rubber.
• the rubber is desirably at least partially cross-linked, and may be completely or fully cross-linked.
• the partial or complete cross-linking can be achieved by adding an appropriate rubber curative to the blend of polyolefin and elastomer and vulcanizing the rubber to the desired degree under conventional vulcanizing conditions.
• dynamic vulcanization means a vulcanization or curing process for a rubber contained in a thermoplastic elastomer composition, wherein the rubber is vulcanized under conditions of high shear at a temperature above the melting point of the polyolefin component.
• the rubber is thus simultaneously cross-linked and dispersed as fine particles within the polyolefin matrix, although other morphologies may also exist.
• Dynamic vulcanization is effected by mixing the thermoplastic and elastomer components at elevated temperature on conventional mixing equipment such as roll mills, banbury mixers, brabender mixers, continuous mixers, mixing extruders and the like.
• the compositions can be processed and reprocessed by conventional plastic processing techniques such as extrusion, injection molding and compression molding.
• plastic processing techniques such as extrusion, injection molding and compression molding.
• Those of ordinary skill in the art will appreciate the appropriate quantities, types of cure systems and vulcanization conditions required to carry out the vulcanization of the rubber.
• the rubber can be vulcanized using varying amounts of curative, varying temperature and varying time of cure in order to obtain the optimum cross- linking desired.
• any known cure system for the rubber can be used, so long as it is suitable under the vulcanization conditions with the specific olefinic rubber or combination of rubbers being used with the polyolefin.
• These curatives include sulphur, sulphur donors, metal oxides, resin systems, peroxide-based systems, hydrosilation with platinum or peroxide and the like both with and without accelerators and coagents.
• the terms fully vulcanized and completely vulcanized as used in the specification means that the rubber component to be vulcanized has been cured to a state in which the elastomeric properties of the cross-linked rubber are similar to those of the rubber in its conventional vulcanized state, apart from the thermoplastic elastomer composition.
• the degree of cure can be described in terms of gel content or, conversely, extractable components. Alternatively, the degree of cure may be expressed in terms of cross-link density.
• inventive compounds may also include other curatives and reinforcing and non-reinforcing aides, antioxidants, stabilizers, rubber processing oils, extender oils, lubricants, antiblocking agents, antistatic agents, waxes, foaming agents, pigments, flame retardants and any of the other processing aids known in the rubber compounding art.
• esters may include either aliphatic mono or diesters or alternatively oligomeric aliphatic esters or alkyl ether esters.
• aliphatic tallate/oleate esters such as isooctyl tallate and n-butyl tallate are particularly preferred esters.
• the amount of polyolefin thermoplastic found to provide useful compositions is generally from about 10 to 90 weight percent, based on the weight of the rubber and polyolefin.
• the polyolefin thermoplastic content will range from about 10 to 40 percent by weight.
• thermoplastic elastomers of the invention set forth in the examples of the following tables.
• the raw materials used in the compositions are more fully described in the chart following the tables.
• TPEs were prepared by melt blending a rubber, a thermoplastic and optionally a diluent at T ⁇ 180°C in a high shear device, in the presence of curatives such that mixing and vulcanization occurred simultaneously.
• Other additives such as fillers, diluents (oil and plasticizer), antidegradants, etc., may be optionally added.
• Epsyn P597 rubber extended with 100 parts paraffinic oil, Ziegler Catalyst, (Copolymer Rubber & Chemical Co. - DSM)
• Vulkup 40 KE (Hercules) '
• thermoplastic elastomeric composition that fully satisfies the objects and advantages set forth above. While the invention has been described in conjunction while the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives will be apparent to those skilled in the art in light of the foreign description. Accordingly, it is intended to embrace all such alternatives, modification and variations as fall within the spirit and broad scope of the appended claims.

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• 1997
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