MXPA99007265A - Thermoplastic elastomer compositions from branched olefin copolymers - Google Patents

Abstract

The invention relates to a thermoplastic elastomer composition comprising a branched olefin copolymer derived from olfinically unsaturated monomers capable of insertion polymerization having A) a Tg as measured by DSC less than or equal to 10°C;B) Tm greater than 80°C;C) an elongation at break of greater than or equal to 300%;D) a tensile strength of greater than or equal to 1,500 psi (10,300 kPa);and E) an elastic recovery of greater than or equal to 50%. The invention also relates to process for preparing the invention composition comprising:A) polymerizing ethylene or propylene and optionally, one or more copolymerizable monomers in a polymerization reaction under conditions sufficient to form copolymer having greater than 40%chain end-group unsaturation;B) copolymerizing the product of A) with ethylene and one or more comonomers so as to prepare said branched olefin copolymer. The branched olefin copolymer compositions of the invention are suitable as replacements for styrene block copolymer compositions and in other traditional thermoplastic elastomer applications.

Description

COMPOSITIONS OF THERMOPASTIC ELASTOMER FROM RAMIFIED OLEFIN COPOLYMERS Technical Field The invention relates to thermoplastic elastomer compositions comprising branched olefin copolymers having crystallizable polyolefin side chains, incorporated into low crystallinity polyethylene backbones. Prior Art The copolymers of tri-blocks and multiple blocks are well known in the field of elastomeric polymers useful as thermoplastic elastomer compositions ("TPE") due to the presence of "soft" (elastomeric) blocks connecting blocks. hard "(crystallizable or glassy). The hard blocks link the polymer network together at typical temperatures of use. However, when heated above the melting temperature or the glass transition temperature of the hard block, the polymer flows easily, exhibiting thermoplastic behavior. See, for example, G. Holden and N.R. Legge, Thermoplastic Elastomers: A Comprehensive Review, Oxford University Press (1987). The best commercially known class of TPE polymers is that of styrenic block copolymers (SBC), typically linear polymeric tri-blocks such as styrene-isoprene-styrene and styrene-butadiene-styrene, the latter of which, when they are hydrogenated, they become essentially copolymers in blocks of styrene- (ethylene-butene) -styrene. SBC radial and branched star copolymers are also well known. These copolymers are typically prepared by sequential anionic polymerization or by chemical coupling of linear block copolymers. The glass transition temperature (Tg) of the typical TPE SBC is equal to or less than about 80-90 ° C, thus presenting a limitation on the utility of these copolymers under conditions of use of higher temperatures. See, "Structures and Properties of Block Polymers and Multiphase Polymer Systems: An Overview of Present Status and Future Potential", S.L. Add to the Sixth Biennial Symposium on Polimeros de Manchester (Manchester UMIST, March 1976). Polymerization of olefins by insertion, or coordination, can provide economically more efficient means of providing copolymer products, both due to process efficiencies and differences in costs of the feedstocks. In this manner, useful TPE polymers from olefinically unsaturated monomers, such as ethylene and C3-C8-olefins, have been developed and are also well known. Examples include physical blends of thermoplastic olefins ("TPO"), such as polypropylene with ethylene-propylene copolymers, and similar physical mixtures where the ethylene-propylene, or ethylene-propylene-diolefin phase, is dynamically vulcanized so as to keep discrete particles, in soft phase, well dispersed, in a polypropylene matrix. See, N.R. Legge, "Thermoplastic Elastomer Categories: A Comparison of Physical Properties", Elastomerics, pages 14-20 (September 1991), and references cited therein. The use of metallocene catalysts for polymerization of olefins has led to additional contributions to the field. U.S. Patent No. 5,391,629 discloses thermoplastic elastomer composites comprising linear block and tapered polymers from ethylene and alpha-olefin monomers. It is said that polymers are possible having hard and soft segments with single-site metallocene catalysts that are capable of preparing both segments. Examples of linear thermoplastic elastomers are provided having hard blocks of high density polyethylene or isotactic polypropylene and soft blocks of ethylene-propylene rubber. Japanese Advance Publication H4-337308 (1992) describes what is said to be a polyolefin copolymer product made by polymerizing propylene first so as to form isotactic polypropylene and then copolymerizing the polypropylene with ethylene and propylene, both polymerizations in the presence of an organoaluminum compound and a bisciclopentadienyl zirconium dihalide compound, bridged with silicon. Datta et al (D.J. Lohse, S. Datta and E.N. Kresge, Macromolecules 24, 561 (1991)), describe vertebral columns of EP functionalized with cyclic diolefins by terpolymerization of ethylene, propylene and diolefin. The "soft block" of EP, statistically functionalized, was then copolymerized with propylene in the presence of a catalyst that produces isotactic polypropylene. In this way, some of the "hard" polypropylene chains were grafted through residual olefinic unsaturation into the "soft" EP block as it formed. See also, EP-AO 366 411. A limitation of this class of reactions, in which chains with multiple functionalities are used in subsequent reactions, is the formation of undesirable high molecular weight material, typically referred to as a gel in the material . U.S. Patent No. 4,999,403 discloses similar graft copolymer compounds where the functional groups in the EPR backbone are used to graft isotactic polypropylene having reactive groups. In both cases, it is said that the graft copolymers are useful as compatibilizing compounds for physical mixtures of isotactic polypropylene and ethylene-propylene rubber. SUMMARY OF THE INVENTION The invention relates to a thermoplastic elastomer composition comprising a branched olefin copolymer derived from ethylenically unsaturated monomers capable of insertion polymerization, having A) a Tg, measured by DSC, less than or equal to 10 ° C.; B) a melting temperature (Tm) greater than 80 ° C; C) an elongation at break greater than or equal to 300%, preferably greater than 500%; D) a tensile strength greater than or equal to 1,500 psi (10,300 kPa), preferably greater than 2,000 psi (13,800 kPa); and E) an elastic recovery greater than or equal to 50%. More particularly, the branched olefin copolymer is one comprising crystallizable side chains derived from olefins, optionally with one or more copolymerizable monomers, such that the T is greater than 80 ° C, and the number average molecular weight (Mn) is greater than 1,500 and less than 45,000. The thermoplastic elastomer composition of the invention can be prepared by the process comprising: A) copolymerizing an olefin, optionally with one or more copolymerizable monomers, in a polymerization reaction under conditions sufficient to form crystallizable or glassy copolymer having more than 40% unsaturation of chain end groups; B) copolymerizing the product of A) with ethylene and one or more copolymerizable monomers in order to prepare said branched olefin copolymer. This thermoplastic elastomer composition exhibits elastic properties comparable or superior to those of the traditionally important SBC copolymers, thus providing alternative means as sources of feedstock and industrial production for this important class of commercial products. Brief Description of the Drawings Figure 1 illustrates a comparison of measured physical properties of branched olefin copolymers of the invention with a commercially available block copolymer thermoplastic elastomer elastomer. Detailed Description of the Invention The thermoplastic elastomer compositions of this invention comprise branched copolymers wherein both the backbone of the copolymer and the polymer side chains are derived from polymerized monoolefins under conditions of coordination or insertion with activated organometallic transition metal catalyst compounds. The side chains are copolymerized so as to exhibit crystalline, semi-crystalline or glassy properties, suitable for hard phase domains according to the meaning understood in the art of these terms, and they bind to a polymeric backbone that is less crystalline or glassy than the side chains, preferably substantially amorphous, so as to be suitable for the soft complementary domains characteristic of the thermoplastic elastomer compositions. The crystallizable side chains comprise chemical units capable of forming crystalline or glassy polymer segments under conditions of insertion polymerization. Monomers known to meet this criterion are ethylene, propylene, 3-methyl-1-pentene, and their copolymers, including copolymers of ethylene with α-olefin, cyclic olefin or styrenic co-monomers. Ethylene or propylene copolymer side chains are preferred with the proviso that the amount of co-monomer is insufficient to disturb the crystallinity, such that the Tm is reduced below 80 ° C. Suitable co-monomers include C3-C20 α-olefins or geminally disubstituted monomers, C5-C25 cyclic olefins, styrenic olefins and substituted lower alkyl analogs of (C3-C8) carbons of the cyclic and styrenic olefins. In this way, typically, the side chains may comprise from 85 to 100 mole% ethylene, and from 0 to 15 mole% co-monomer, preferably 90-99 mole% ethylene and 1-10 mole% co-monomer. monomer, most preferably 94-98 mole% ethylene and 2-6 mole% co-monomer. Alternatively, the side chains may comprise from 90 to 100 mol% propylene, and from 0 to 10 mol% co-monomer, preferably 92-99 mol% propylene and 1-8 mol% co-monomer, most preferably 95-98 mole percent propylene and 2-5 mole percent co-monomer. In particular, as the Mn value of the side chains increases by about 3,000, it is preferred to introduce small amounts of co-monomer to minimize brittleness, for example about 0.2-4.0 mole% of co-monomer. The selection of co-monomer may be based on properties other than the ability to disturb the crystallinity, for example a longer olefin comonomer, such as 1-octene, may be preferred over a shorter olefin such as 1-butene for improved tear of polyethylene film. For improved elasticity properties of polyethylene film or barrier, a cyclic comonomer such as norbornene or substituted alkyl norbornene may be preferred over an alpha-olefin. The side chains can have a narrow or broad molecular weight distribution (Mw / Mn), for example from 1.1 to 30, typically 2-8. Additionally, the side chains may have different co-monomer compositions, for example including the orthogonal compositional distributions described in U.S. Patent No. 5,382,630 (CDBI greater than 50%), incorporated herein by reference for purposes of US patent practice. Optionally, mixtures of side chains with different molecular weights and / or compositions can be used. The Mn value of the side chains is within the range of greater than or equal to 1,500 and less than or equal to 45,000. Preferably, the Mn value of the side chains is from 1,500 to 30,000, and most preferably Mn is from 1,500 to 25,000. The number of side chains is related to the Mn value of the side chains such that the total weight ratio of the side chains to the total weight of the polymer backbone segments between and outside the incorporated side chains is less than 60. %, preferably 40-50%. The molecular weight is determined here by measurements of gel permeation chromatography (GPC) and differential refractive index (DRI). A preferred branched olefinic copolymer within this class will have a melting enthalpy (? Hf), as measured by differential scanning calorimetry, less than or equal to 90 cal / g (measured by integrating recorded thermal fluxes at temperatures greater than or equal to 80 ° C. while exploring at a value greater than or equal to 5 ° C / min). The spine, or the polymeric spine segments, when taken together with the side chain interruption of the spinal structure, must have a Tm (or Tg if it does not exhibit a Tm) than the side chains. In this way, it will preferably comprise segments of chemical units that do not have a measurable crystallinity, or having a Tg less than -10 ° C. The spine segments, taken together, will typically have a Tm less than or equal to 80 ° C and a Tg less than or equal to -10 ° C. Elastomeric spinal columns will be particularly suitable, and will typically be composed of ethylene and one or more C3-C12 α-olefins or diolefins, particularly propylene and 1-butene. Other copolymerizable monomers include geminally disubstituted olefins such as isobutylene, cyclic olefins such as cyclopentene, norbornene and substituted alkyl norbornenes, and styrenic monomers such as styrene and substituted alkyl styrenes. Vertl columns of low crystallinity are suitable, examples being copolymers of ethylene with high content of co-monomer (as described above), for example greater than 8 mol% of co-monomer. As indicated above, the spinal column mass will typically comprise at least 40% by weight of the total polymer mass, that of the spine and side chains together, so that the spine will typically have a nominal heavy weight average molecular weight. (Mw) at least equal to or greater than about 50,000. The term "nominal" is used to indicate that the direct measurement of Mw of the spine is largely impossible, but that the characterization of the copolymer product will exhibit Mw measurements that correlate with a narrow approximate weight of the polymeric backbone, including only the monoolefin mer derivatives and the insertion fractions of the lateral branches. The branched olefin copolymers comprising the side chains and backbones will typically have an Mw equal to or greater than 50,000, as measured by GPC / DRI, as defined for the examples. The Mw value typically can exceed 300,000, preferably 200,000, up to 500,000 or more. The thermoplastic elastomer composition of the invention can be prepared by a process comprising: A) copolymerizing ethylene or propylene, optionally with one or more copolymerizable monomers, in a polymerization reaction under conditions sufficient to form a copolymer having more than 40% unsaturation of chain end groups, a Tm greater than or equal to 80 ° C and a Tg less than or equal to 10 ° C; B) copolymerizing the product of A) with ethylene and one or more copolymerizable monomers in order to prepare said branched olefin copolymer. For ethylene-based macromers prepared in step A), the Tg is preferably less than -5 ° C, more preferably less than -10 ° C. Step A) of the process can be usefully implemented in a solution process in which ethylene and, optionally, one or more copolymerizable monomers are contacted with an activated transition metal olefin polymerization catalyst. by an alumoxane co-catalyst, the molar ratio of aluminum to transition metal being less than about 220: 1. The terminally unsaturated copolymer population thus formed, with or without separation of the copolymer product having only saturated ends, can then be copolymerized with ethylene and copolymerizable monomers in a separate reaction by polymerization of ethylene in solution, in slurry or in the gas phase. , with an activated transition metal insertion polymerization catalyst, particularly a catalyst capable of incorporating the ethylene copolymers in said branched olefin copolymer. Alternatively, step A) of the process can be implemented in a solution process in which propylene and, optionally, one or more copolymerizable monomers, are contacted with a stereo transition metal olefin polymerization catalyst. -rigid, one capable of producing stereo-regular polypropylene, activated by any suitable co-catalyst, the reaction temperature maintained at sufficiently high levels so as to achieve significant populations of terminally unsaturated polymer chains, for example to more than about of 85 ° C, preferably more than around 90 ° C. The terminally unsaturated copolymer population thus formed, with or without separation of the copolymer product having only saturated ends, can then be copolymerized with ethylene and copolymerizable monomers, or other selection of monomers suitable for the preparation of low crystallinity polymers, in a separate reaction by polymerization of ethylene in solution, in slurry or in gaseous phase, with an activated transition metal insertion polymerization catalyst, particularly a catalyst capable of incorporating the propylene copolymers in said branched olefin copolymer having the low crystallinity backbone. Sufficient conditions for forming the side-chain ethylene copolymer include using ratios of ethylene and co-monomer reagents to ensure the described constitution of the side chain olefin-derived unit, more catalyst and process conditions that lead to the formation of unsaturated chain ends. The teachings of U.S. Provisional Patent Application Serial No. 60 / 037,323, filed on February 7, 1997, are specific to the selection and use of suitable catalysts for preparing macromeric copolymer chains with a high unsaturation yield. vinyl. The metallocene catalyst used in step A) in the preparation of the macromer containing unsaturation can be essentially any catalyst capable of polymerization by insertion of ethylene, it can be one capable of high incorporation of co-monomer (see below) or of low incorporation of co-monomer. Those with low incorporation capacity are typically the ones that are most congested at the metal coordination site, so that the unbridged and substituted metallocene catalysts are particularly suitable. See also U.S. Patent No. 5,498,809 and international publications WO 94/19436 and WO 94/13715, which describe means of preparing copolymers of ethylene and 1-butene vinylidene terminated in high yields. See also the teachings of the United States patent application Serial No. 08/651, 030, pending, filed May 21, 1996, regarding the preparation of ethylene-isobutylene copolymers having high levels of unsaturation of vinylidene chain ends. Through the above description, and below, the phrase "end of chain" or "terminal", when referring to unsaturation, means olefinic unsaturation suitable for insertion polymerization, whether or not precisely located within the term of a chain. See also U.S. Patent Nos. 5,324,801 and 5,621,054, which are directed to alternating cyclic ethylene-olefin copolymers having crystalline melting points of 235 ° C and more.; the macromers produced with the suitable catalysts of these descriptions will have effective glassy attributes to function as the hard phase component of the thermoplastic elastomers of this invention. All documents of this paragraph are incorporated herein by reference. In a particular embodiment, an ethylene-containing polymer-containing macromer product, suitable as a branch for a subsequent polymerization reaction, can be prepared under solution polymerization conditions with preferred molar ratios of aluminum in the alkyl activator alumoxane, for example methyl alumoxane (MAO), to transition metal. Preferably, that level is greater than or equal to 20 and less than or equal to 175; more preferably, greater than or equal to 20 and less than or equal to 140; and most preferably, greater than or equal to 20 and less than or equal to 100. The temperature, pressure and reaction time depend on the selected process but are generally within the normal ranges for a process in solution. In this way, temperatures can vary from 20 to 200 ° C, preferably from 30 to 150 ° C, and more preferably from 50 to 140 ° C. Reaction pressures may generally vary from atmospheric to 345 MPa, preferably to 182 MPa. For typical reactions in solution, temperatures will typically vary from ambient to 190 ° C, with ambient pressures to 3.45 MPa. Reactions can be run on charges. The conditions for suitable slurry reactions are similar to the solution conditions, except that the reaction temperatures are limited to those below the melting temperature of the polymer. In an additional, alternative reaction configuration, a supercritical fluid medium can be used at temperatures up to 250 ° C and pressures up to 345 MPa. Under high temperature and pressure reaction conditions, the macromer product of lower molecular weight ranges are typically produced, for example, with Mn of about 1,500. In an alternative embodiment, a macromeric product containing propylene, containing polymeric vinyl, can be prepared under solution polymerization conditions with suitable metallocene catalysts to prepare either isotactic polypropylene or syndiotactic polypropylene. A preferred reaction process for propylene macromers having high levels of terminal vinyl unsaturation is described in U.S. Patent Application Serial No. 60 / 067,783, filed December 10, 1997, attorney's file No. 97B075. Typically used catalysts are bridged, helical or asymmetric, stereo-rigid metallocenes. See, for example, U.S. Patent Nos. 4,892,851; 5,017,714; 5,132,281; 5,155,080; 5,296,434; 5,278,264; 5,318,935, WO-A-PCT / US92 / 10066, WO-A-93/19103, EP-A2-0 577 581, EP-A1-0 578 838, and the academic literature "The Influence of Aromatic Substituents on the Polymerization Behavior of Bridged Zirconocene Catalysts ", Spaleck, W. et al., Organometallics 1994, 13, 954-963, and" Ansa-Zirconocene Polymerization Catalysts with Annelated Ring Ligands-Effects on Catalytic Activity and Polymer Chain Lengths ", Brinzinger, H. and collaborators, Organometallics 1994, 13, 964-970, and the documents referred to therein. Preferably, for isotactic polypropylene, the stereo-rigid transition metal catalyst compound is selected from the group consisting of bis (indenyl) zirconocenes or bridged hafnocenes. In a preferred embodiment, the transition metal catalyst compound is bis (indenyl) zirconocene or bridged dimethylsilyl hafnocene. More preferably, the transition metal catalyst compound is dimethylsilyl (2-methyl-4-phenylindenyl) zirconium dichloride or hafnium or dimethyl. In another preferred embodiment, the transition metal catalyst is an (indenyl) hafnocene dimethylsilyl bridged such as dimethylsilyl bis (indenyl) hafnium dimethyl or dichloride. The method for preparing propylene-based macromers having a high percentage of vinyl terminal linkages involves: a) contacting, in solution, propylene, optionally a minor amount of copolymerizable monomer, with a catalyst composition containing the metal catalyst compound of activated, stereo-rigid transition, at a temperature of about 90 to about 120 ° C; and b) recovering isotactic or syndiotactic polypropylene chains having number average molecular weights from about 2,000 to about 50,000 Daltons. Preferably, the solution comprises a hydrocarbon solvent. More preferably, the hydrocarbon solvent is aromatic. Also, the propylene monomers are preferably contacted at a temperature of 95 to 115 ° C. More preferably, a temperature of 100 to 110 ° C is used. Most preferably, the propylene monomers are contacted at a temperature of 105 to 110 ° C. The pressures of the reaction can vary from atmospheric to 345 MPa, preferably to 182 MPa. The reactions can be run in loads or continuously. Conditions for suitable slurry type reactions will also be suitable and are similar to the conditions in solution, the polymerization being run typically in liquid propylene under pressures suitable for this. All documents are incorporated by reference herein. Additionally, the branched olefin copolymer thermoplastic elastomer composition of the invention can be prepared directly from the selected olefins concurrently in the presence of a mixed catalyst system comprising at least a first transition metal olefin polymerization catalyst, capable of preparing ethylene or propylene copolymers having more than 40% unsaturation of chain end groups, and at least one second transition metal olefin polymerization catalyst, capable of incorporating the side chains of the homopolymer or ethylene copolymer or propylene in said branched olefin copolymer. This in situ method can be implemented by any method that allows both the preparation of unsaturated macromers having crystalline, semi-crystalline or glassy properties, and the copolymerization of the macromers with co-monomers constituting the low crystallinity backbone, such that the branched copolymer be prepared. Gaseous, slurry and solution processes can be used under conditions of temperature and pressure known to be useful in such processes. Suitable first catalyst compounds which, when activated, can achieve high chain end unsaturations, specifically include those identified above with respect to the preparation of high vinyl or vinylidene macromers. Preferably, catalysts which are active for ethylene homopolymerization but which do not appreciably incorporate monomers with higher carbon numbers, as discussed above, or which only do so with a congruent reduction in the Mn value, will be particularly suitable for the preparation of crystalline or glassy side chains in the concurrent method, or in situ, of preparing the thermoplastic copolymer compositions of the invention, as long as the Mn value can be raised or maintained over the minimum of the side chains. Suitable second catalyst compounds include those which are capable of good co-monomer incorporation without significant depression in the Mn value for the polymer backbone under the conditions of temperature and pressure used. The teachings of the provisional patent application of the United States, Serial No. 60 / 037,323, filed on February 7, 1997, are specific to the selection and use of suitable catalysts to prepare branched olefin copolymers and are directed to suitable catalyst compounds for high incorporation of comonomers and macro-monomers . As indicated therein, the preferred catalyst compounds for assembling the branched olefin copolymers from vinyl or vinylidene-containing macromers, ethylene and copolymerizable co-monomers, include the bridged bis-cyclopentadienyl and monocyclopentadienyl group IV metal compounds of the patents of the United States Nos. 5,198,401; 5,270,393; 5,324,801; 5,444,145; 5,475,075; 5,635,573; the international publications WO 92/00333 and WO 96/00244; see also the non-bridged monocyclopentadienyl group IV metal compounds of U.S. Patent Application Serial No. 08 / 545,973, filed October 20, 1995, and the bis-amido and bis-transition metal catalysts. Arylamido from U.S. Patent No. 5,318,935 and U.S. Patent Application Serial No. 08 / 803,687, filed February 24, 1997, and the α-diimine nickel catalyst complexes of the WO 96 publication / 23010. According to these teachings, the transition metal catalyst compounds are typically used with activating co-catalyst components as described, for example alkyl alumoxanes and ionizing compounds capable of providing a non-coordinating, stabilizing anion. The teachings of each of the documents in this paragraph are also incorporated by reference herein. Industrial Application The thermoplastic elastomer compositions according to the invention will have use in a variety of applications where other thermoplastic elastomer compositions have found use. Such uses include, but are not limited to those known for block styrene copolymers, for example copolymers of styrene-isoprene-styrene and styrene-butadiene-styrene, and their hydrogenated analogs. Such include a variety of uses such as spinal polymers in adhesive compositions and molded articles. These applications will benefit from the range of increased use temperatures, typically exceeding the 80-90 ° C limitation of the SBC copolymer compositions. The compositions of the invention will also be suitable as compatibilizing compounds for physical blends of polyolefins. Additionally, due to the inherent tensile strength, elasticity and processability, extruded films, coatings and packing compositions comprising the thermoplastic elastomer compositions of the invention can be prepared, optionally as modified with additives and conventional adjuvants. Furthermore, in view of the preferred process of preparation using insertion polymerization of readily available olefins, the thermoplastic elastomer compositions of the invention can be prepared with low cost petro-chemical feedstock, under conditions of low energy consumption (in comparison with conditions of processing in the molten state, of multiple steps, or anionic polymerization at low temperature, where vulcanization is needed to achieve morphologies of discrete thermoplastic elastomer). EXAMPLES In order to illustrate the present invention, the following examples are provided. Such are not intended to limit the invention in any respect, but are only provided for purposes of illustration. General: all polymerizations were carried out in a 1 liter Zipperclave reactor, equipped with a water jacket for temperature control. The liquids were measured in the reactor using calibrated sight glasses. High purity hexane, toluene and butene feeds (more than 99.5%) were purified by first passing through basic alumina activated at high temperature under nitrogen, followed by 13x molecular sieve activated at high temperature under nitrogen. Polymerization-grade ethylene was supplied directly in a line lined with nitrogen and used without further purification. Light methylalumoxane, 10% (MAO), in toluene, from Albermarle Inc., was used in stainless steel cylinders, divided into 1 liter glass containers, and stored in a laboratory glove box at room temperature. Ethylene was added to the reactor, as necessary, to maintain the total system pressure at the reported levels (operation in semi-loads). The ethylene flow rate was monitored using a Matheson mass flow meter (model No. 8272-0424). To ensure that the reaction medium was well mixed, a flat paddle stirrer was used rotating at 750 rpm. Reactor preparation: the reactor was first cleaned by heating to 150 ° C in toluene to dissolve any polymer residues, then cooled and drained. Next, the reactor was heated using a water jacket at 110 ° C and the reactor was purged with nitrogen flowing for a period of about 30 minutes. Prior to the reaction, the reactor was further purged using 10 cycles of nitrogen pressurization / ventilation (at 100 psi) and 2 cycles of ethylene presurization / ventilation (at 300 psi). The cycle served two purposes: (1) to intensely penetrate all dead ends, such as pressure gauges, to purge fugitive contaminants, and (2) to displace nitrogen in the system with ethylene, and (3) to test the reactor in terms of pressure. Catalyst preparation: all catalyst preparations were carried out in an inert atmosphere with less than 1.5 ppm H20 content. In order to accurately measure small amounts of catalyst, often less than 1 mg, fresh catalyst solution / dilution methods were used in the catalyst preparation. To maximize the solubility of the metallocenes, toluene was used as the solvent. Stainless steel transfer tubes were washed with MAO to remove impurities, drained, and the activator and catalyst were added by pipetting, first MAO. Macromer synthesis: first, the catalyst transfer tube was attached to a reactor gate under a continuous flow of nitrogen to purge ambient air. Next, the reactor was purged and tested for pressure, as noted above. Then, 600 ml of solvent was charged to the reactor and heated to the desired temperature. Co-monomer was then added (if present), the temperature was allowed to equilibrate, and the pressure of the base system was recorded. The desired partial pressure of ethylene was added at the top of the base system pressure. After allowing the ethylene to saturate the system (as indicated by the zero flow of ethylene), the catalyst was injected into a pulse using high solvent pressure. The progress of the reaction was monitored by reading the ethylene outlet of the electronic mass flow meter. When the desired amount of macromer had accumulated, the ethylene flow was terminated and the reaction was terminated by heating (approximately 1 minute) at 150 ° C for 30 minutes. At the end of the termination step, the reactor was cooled to the desired temperature for the assembly reaction of the LCB block (below) and a macromer sample was removed for analysis. Assembly of the LCB block structures: all reactions of long chain, branched olefin copolymer (LCB) assembly were carried out in toluene, using ethylene at 100 psi and catalyst (C5Me4SiMe2NC12H23) TiCl2, activated with MAO. Butene was used as a co-monomer in most of the syntheses, but select reactions were carried out using norbornene comonomer in order to generate samples used to quantify the LCB content. The reaction was terminated by injection of methanol when the desired amount of polymer was produced (total mass accumulated). It was observed that the pressure drop of the reactor and the ethylene uptake were stopped within about 10 seconds from the injection. The product was poured into an excess of isopropyl alcohol and evaporated to dryness. In another example (Example 3), catalysts of Cp2ZrCl2 and (C5Me4SiMe2NC12H23) TiCl2 were used in mixed, single-step metallocene synthesis, where the macromers were prepared concurrently with the spine and incorporated therein. Catalyst pairing: for the example of the mixed metallocene in situ, the pair of metallocene catalysts was selected such that a good incorporation catalyst and a poor incorporation catalyst were used. For this technology, the good incorporator will typically exhibit three times the incorporation capacity of the poor incorporator, or even more preferably five times the incorporation capacity. The co-monomer incorporation ability is defined and measured for each catalyst compound, for the purposes of the present invention, in terms of weight percentage of butene incorporation using a defined standard reaction condition, as follows. A 1 liter autoclave reactor is purged 2 hours at 90 ° C with high purity nitrogen. The system then purged of nitrogen using ethylene flowing. Next, 600 ml of toluene and 50 ml of liquid butene were added. The system is left to equilibrate at 90 ° C. Next, ethylene is added at 100 psig until the solution is saturated. 1 mg of catalyst is added to 0.5 ml of 10% by weight MAO, in a stainless steel addition tube in a glovebox under inert atmosphere. Depending on the reactivity of the catalyst, more or less catalyst / MAO solution may be required to ensure substantial levels of polymerization without excessive reaction exotherms. The catalyst is injected into the reactor using solvent under pressure. The reactor pressure is maintained at 100 psig throughout the reaction, adding ethylene as required. The reaction is terminated before the compositions of the reagents change substantially within the reactor (less than 20% conversion, determined by analysis of the reaction product). The co-monomer incorporation is measured by 1 H NMR and is reported as ethyl groups per 1,000 carbon atoms. Example 1 Catalyst preparation: a stainless steel catalyst addition tube was prepared as noted above. An aliquot of 1 ml of 10% methylalumoxane (MAO) solution in toluene was added, followed by 5 ml of a solution in toluene containing 16 mg of (C5Me4SiMe2NC12H23) TiCl2. The sealed tube was removed from the glovebox and connected to a reactor gate under a continuous flow of nitrogen. A flexible stainless steel line of the reactor supply manifold was connected to the other end of the addition tube under a continuous flow of nitrogen.

Macromer synthesis: the reactor was purged of nitrogen simultaneously and tested for pressure using two ethylene fill / purge cycles (at 300 psig). Then, the reactor pressure was raised to approximately 40 psi to maintain a positive pressure in the reactor during the installation operations. The water temperature of the jacket was set at 90 ° C and 600 ml of toluene and 10 ml of butene were added to the reactor. The agitator was set at 750 rpm. Additional ethylene was added to maintain a positive gauge pressure in the reactor as ethylene in gas phase is absorbed into the solution. The reactor temperature controller was set at 90 ° C and the system was allowed to reach steady state. The ethylene pressure regulator was then set at 100 psig and ethylene was added to the system until a stable state was reached, as measured by zero ethylene uptake. The reactor was isolated and a pressurized toluene pulse at 300 psig was used to force the catalyst solution from the addition tube into the reactor. The ethylene feed manifold at 100 psig was immediately opened to the reactor in order to maintain a constant reactor pressure when the ethylene was consumed by the reaction. After 15 minutes of reaction, the reaction solution was rapidly heated to 150 ° C for 30 minutes, then cooled to 90 ° C. A sample of the pre-polymerized macromer was removed from the reactor.

Synthesis of LCB block copolymer: a stainless steel catalyst addition tube was prepared as noted above. An aliquot of 0.5 ml of a solution of 10% methylalumoxane (MAO) in toluene was added to the tube, followed by 1 ml of a solution in toluene containing 0.5 mg of (C5Me4SiMe2NC12H23) TiCl2 per ml. The sealed tube was removed from the glovebox and connected to a reactor gate under a continuous flow of nitrogen. A flexible stainless steel line of the reactor supply manifold was connected to the other end of the addition tube under a continuous flow of nitrogen. The temperature controller of the reactor was set at 90 ° C. Next, 70 ml of butene was added to the macromer-containing reactor and the system was allowed to reach thermal equilibrium. Ethylene was added immediately to the system at 100 psig (total). After allowing the ethylene to saturate the system (as indicated by zero ethylene flow), the catalyst was injected into a pulse using high pressure solvent. The progress of the reaction was monitored by reading the ethylene outlet of the electronic mass flow meter. The reaction was terminated by methanol injection after 15 minutes. The product was poured into an excess of isopropyl alcohol and evaporated to dryness. The total yield of the LCB block copolymer was 42.6 g. Example 2 Catalyst preparation: a stainless steel catalyst addition tube was prepared as noted above. An aliquot of 0.5 ml of 10% methylalumoxane (MAO) solution in toluene was added, followed by 5 ml of a solution in toluene containing 8 mg of Cp2ZrCl2. The sealed tube was removed from the glovebox and connected to a reactor gate under a continuous flow of nitrogen. A flexible stainless steel line from the reactor supply manifold was connected to the other end of the addition tube under a continuous flow of nitrogen. Macromer synthesis: the reactor was purged of nitrogen simultaneously and tested for pressure using two ethylene fill / purge cycles (at 300 psig). Then, the reactor pressure was raised to approximately 20 psi to maintain a positive pressure in the reactor during the installation operation. The water temperature of the jacket was set at 90 ° C and 600 ml of toluene and 2 ml of 80.6% by weight norbornene in toluene were added to the reactor. The agitator was set at 750 rpm. Additional ethylene was added to maintain a positive gauge pressure in the reactor to the gas phase ethylene sorbent in the solution. The reactor temperature controller was set at 90 ° C and the system was allowed to reach steady state. The ethylene pressure regulator was then set at 30 psig and ethylene was added to the system until a stable state was reached, as measured by zero ethylene uptake. The reactor was isolated and a pressurized toluene pulse was used at 300 psig to force the catalyst solution from the addition tube to the reactor. The ethylene supply manifold at 30 psig was immediately opened to the reactor in order to maintain a constant pressure in the reactor when the ethylene was consumed by the reaction. After 15 minutes of reaction, the reaction solution was rapidly heated to 150 ° C for 30 minutes, then cooled to 90 ° C. A sample of the pre-polymerized macromer was removed from the reactor. Synthesis of LCB block copolymer: a stainless steel catalyst addition tube was prepared as indicated above. An aliquot of 0.5 ml of 10% methylalumoxane (MAO) solution in toluene was added, followed by 1 ml of a solution in toluene containing 1 mg of (C5Me4SiMe2NC12H23) TiCl2 per ml. The sealed tube was removed from the glovebox and connected to a reactor gate under a continuous flow of nitrogen. A flexible stainless steel line from the reactor supply manifold was connected to the other end of the addition tube under a continuous flow of nitrogen. The reactor temperature controller was set at 60 ° C. Next, 60 ml of 80.6% norbornene in toluene were added and the system was allowed to reach thermal equilibrium. Ethylene was then added to the system, at 100 psig (total). After allowing the ethylene to saturate the system (as indicated by zero ethylene flow), the catalyst was injected into a pulse using high pressure solvent. The progress of the reaction was monitored by reading the ethylene outlet of the electronic mass flow meter. The reaction was terminated by methanol injection after 5 minutes. The product was poured into an excess of isopropyl alcohol and evaporated to dryness. The total yield of the LCB block copolymer was 91.9 g. Example 3 Catalyst preparation: a stainless steel catalyst addition tube was prepared as noted above. An aliquot of 1 ml of 10% methylalumoxane (MAO) solution in toluene was added, followed by a solution in toluene containing 0.25 mg of (C5Me4SiMe2NC12H23) TiCl2 and 5 micrograms of Cp2ZrCl2. The sealed tube was removed from the glovebox and connected to a reactor gate under a continuous flow of nitrogen. A flexible stainless steel line of the reactor supply manifold was connected to the other end of the addition tube under a continuous flow of nitrogen. Synthesis of LCB block copolymer in situ: the reactor was purged of nitrogen simultaneously and tested for pressure using two ethylene fill / purge cycles (at 300 psig). Then, the reactor pressure was raised to approximately 40 psi to maintain a positive reactor pressure during installation operations. The water temperature of the jacket was set at 90 ° C and 600 ml of toluene and 20 ml of butene were added to the reactor. The agitator was set at 750 rpm. Additional ethylene was added to maintain a positive gauge pressure of the reactor as the ethylene in the gas phase was absorbed into the solution. The reactor temperature controller was set at 90 ° C and the system was allowed to reach steady state. The ethylene pressure regulator was then set at 100 psig and ethylene was added to the system until a stable state was reached, as measured by zero ethylene uptake. The reactor was isolated and a pressurized toluene pulse at 300 psig was used to force the catalyst solution from the addition tube into the reactor. The ethylene feed manifold at 100 psig was immediately opened to the reactor in order to maintain a constant pressure in the reactor when the ethylene was consumed by the reaction. The reaction was terminated by methanol injection after 7 minutes. The product is poured into an excess of isopropyl alcohol and evaporated to dryness. The total yield of the LCB block copolymer was 18.5 g. Properties The structural data for the selected materials are listed in Table 1. In the case of the first two elastomeric examples (1 and 2), the macromer was sampled directly from the reactor and characterized by 1H-NMR and GPC, while for Example 3 (synthesis of mixed metallocene), the properties of the macromer and of the spinal column were attributed from the corresponding reactions of a single metallocene . The stress data were obtained at room temperature and 80 ° C, according to the ASTM method D-14 (in figure 1, the tensile strength at break, at room temperature and 80 ° C, is reported in units of pounds per square inch, while elongation at break is reported as a percentage). Recovery was measured at room temperature using sample specimens identical to those used in the ASTM D-14 test, except that the sample was stretched 150%, then released for 10 minutes, and the percentage recovery to the original dimensions measured directly using reference marks in the test sample. Stress data for selected samples indicate that statistically branched LCB block copolymer formulations exhibited tensile strengths that were equal to or exceeded those of styrenic block copolymers (Kraton®), with slightly defensive elastic recoverability of Kraton®, but well within commercially useful limits (see Table 1 and Figure 1). The tensile strength is the highest for the LCB block copolymer of norbornene (4.011 psi), while the best elastic recovery (89%) was observed in a LCB block copolymer of mixed metallocene and butene. The macromers of both low molecular weight (10K, catalyzed with Cp2ZrCl2) and high Mn (30-40K, catalyzed with (C5Me4SiMe2NC12H23) TiCl2), gave LCB block copolymers with useful properties. LCB ethylene / butene block copolymers exhibit superior elastic properties to a random Exact® 4033 ethylene / butene (E / B) copolymer (Exxon Chemical Company), of similar density and equal to or better than a random ethylene / octene copolymer (E / 0) Engage® 8100 (Dow Chemical Company) of similar density (Table 2). The comparison of linear LCB ethylene / norbornene (E / NB) block counterparts and LCB E / NB indicates that the LCB block copolymer is somewhat defensive in most areas, due in part to its much lower norbornene content. Of course, all LCB block copolymers melt at much higher temperatures than their linear counterparts, due to the crystallizable, low molecular weight branching component. It is interesting to note that LCB block copolymers retain considerable tensile strength even when heated above the melting temperature of their amorphous component (see voltage data at 80 ° C). The high temperature resistance observed can be due to the multiple block type networks in which the amorphous material is anchored to the zones of high fusion, high density by means of the side chains. Characterization of the product: the samples of the branched olefin copolymer product were analyzed by GPC using a Waters 150C high temperature system equipped with a DRl detector, Shodex AT-806MS column and operating at a system temperature of 145 ° C. The solvent used was 1,2,4-trichlorobenzene, from which polymer sample solutions of 0.1 mg / ml concentration were prepared for injection. The total solvent flow rate was 1.0 ml / minute and the injection size was 300 microliters. The GPC columns were calibrated using a series of narrow polystyrenes (obtained from Tosoh Corporation, Tokyo, 1989). For quality control, a wide standard calibration based on the linear PE sample NBS-1475 was used. The standard was run with each carousel of 16 jars. It was injected twice as the first sample of each load. After elution of the polymer samples, the resulting chromatograms were analyzed using the Waters Expert Ease program to calculate the molecular weight distribution and the Mn averages., Mw and Mz. Polymeric analysis: the molecular weight, the co-monomer content, and the structural distributions of unsaturated groups of the reaction products are reported in Table 2. It was found that the concentrations of unsaturated groups (total olefins per 1,000 carbon atoms) carbon) as well as the vinyl group selectivities increase with the reduction of aluminum: metal ratios, all other factors being equal. The reported concentrations of olefin co-monomer can be further increased by reducing the concentration of ethylene in solution (reducing the partial pressure of ethylene or increasing the temperature). Table 2 Comparison of Branched Copolymer Properties with Representative LDPEs Note: E = ethylene; B = butene; NB = norbornene; and O = octene Table 3 Comparison of Properties of Branched Copolymers with Commercial Copolymer Tri-Blocks (Figure 1)

Claims (7)

1. REVINDICATION 1. A thermoplastic elastomer composition, comprising a branched olefin copolymer, derived from olefinically unsaturated monomers capable of insertion polymerization, the copolymer having A) side chains with a number average molecular weight greater than 10,000 and less than 45,000, a Tg, measured by DSC, less than or equal to 10 ° C, and a Tm greater than 80 ° C; B) polymeric segments of elastomeric backbone having a Tg, measured by DSC, less than or equal to -10 ° C; C) an elongation at break greater than or equal to 300%; D) a tensile strength greater than or equal to 1,500 psi (10,300 kPa); and E) an elastic recovery greater than or equal to 50%.
2. 2. The thermoplastic elastomer composition of claim 1, wherein said branched olefin copolymer comprises side chains derived from ethylene, optionally with one or more copolymerizable monomers, such that the Tg of the side chains is less than -10 ° C.
3. The thermoplastic elastomer composition of claim 1, wherein said branched olefin copolymer comprises side chains derived from propylene, optionally with one or more copolymerizable monomers, such that the Tg of the side chains is less than 10 ° C and the Tm is greater than or equal to 110 ° C.
4. 4. The thermoplastic elastomer composition of claim 1, prepared by the process comprising: A) copolymerizing ethylene, optionally with one or more copolymerizable monomers, in a polymerization reaction under conditions sufficient to form copolymer having more than 40% unsaturation of chain end groups; B) copolymerizing the product of A) with ethylene and one or more copolymerizable monomers in order to prepare said branched olefin copolymer.
5. The thermoplastic elastomer composition of claim 4, wherein step A) is conducted by a solution process in which said ethylene and one or more copolymerizable monomers are contacted with a transition metal olefin polymerization catalyst. , activated by means of an alumoxane co-catalyst, the molar ratio of aluminum to transition metal being less than 220: 1.
6. 6. The thermoplastic elastomer composition of claim 5, wherein step B) is conducted in a separate reaction by polymerization of ethylene in solution, in slurry or in gas phase, with an activated transition metal insertion polymerization catalyst. The thermoplastic elastomer composition of claim 4, wherein step A) and step B) are conducted concurrently in the presence of a mixed catalyst system comprising at least one transition metal olefin polymerization catalyst, capable of preparing ethylene copolymers having more than 40% unsaturation of chain end groups and at least one transition metal olefin polymerization catalyst, capable of incorporating the ethylene copolymers into said branched olefin copolymer. Summary The invention relates to a thermoplastic elastomer composition, comprising a branched olefin copolymer, derived from olefinically unsaturated monomers capable of insertion polymerization, having A) a Tg, measured by DSC, less than or equal to 10 ° C; B) a Tm greater than 80 ° C; C) an elongation at break greater than or equal to 300%; D) a tensile strength greater than or equal to 1,500 psi (10,300 kPa); and E) an elastic recovery greater than or equal to 50%. The invention also relates to a process for preparing the composition of the invention, comprising: A) polymerizing ethylene or propylene and, optionally, one or more copolymerizable monomers in a polymerization reaction under conditions sufficient to form copolymer having more than 40% unsaturation of chain end groups; B) copolymerizing the product of A) with ethylene and one or more co-monomers so as to prepare said branched olefin copolymer. The branched olefin copolymer compositions of the invention are suitable as replacements for block styrene copolymer compositions and other traditional thermoplastic elastomer applications. FIGURE 1