Scandium catalyst system and process for producing ethylene / butadiene copolymer

Abstract

To provide a new catalyst system, and a process for producing an ethylene / butadiene copolymer.SOLUTION: A process for producing an ethylene-butadiene copolymer includes copolymerizing butadiene with ethylene in the presence of a catalyst system. The catalyst system includes tris[(trimethylsilyl)methyl]scandium and an aluminum-containing activator.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a scandium catalyst system and a process for producing ethylene / butadiene copolymers. [Background technology]

[0002] Current catalysts used to prepare cis-polybutadiene do not incorporate significant amounts of ethylene. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 6,242,534 [Patent Document 2] U.S. Patent No. 6,207,757 [Patent Document 3] U.S. Patent No. 6,133,364 [Patent Document 4] U.S. Patent No. 6,372,857 [Patent Document 5] U.S. Patent No. 5,395,891 [Patent Document 6] U.S. Patent No. 6,127,488 [Patent Document 7] U.S. Patent No. 5,672,639 [Patent Document 8] U.S. Patent No. 6,608,125 [Patent Document 9] U.S. Patent Publication No. 2003 / 0130535 [Non-patent literature]

[0004] [Non-Patent Document 1] Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000 Parts, 2003, 62nd edition, the Institute of Petroleum, United Kingdom [Non-Patent Document 2] the Journal of the American Chemical Society, Vol. 60, p. 304 (1930) [Non-Patent Document 3] The Vanderbilt Rubber Handbook (1978), pp. 344-346 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable to develop new systems and methods for producing ethylene / butadiene copolymers. [Means for solving the problem]

[0006]

[0003] In some embodiments, a method for producing an ethylene-butadiene copolymer is disclosed. The method includes copolymerizing butadiene with ethylene in the presence of a catalyst system. The catalyst system includes tris[(trimethylsilyl)methyl]scandium; and an aluminum-containing activator. The catalyst system may further include a borate co-activator. In some embodiments, the borate co-activator includes a salt of tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and / or a salt of tetrakis(pentafluorophenyl)borate. The aluminum-containing activator may include an aluminoxane activator. In some embodiments, the aluminoxane activator includes a modified aluminoxane activator. The aluminoxane activator may include a methylaluminoxane activator. In some embodiments, the methylaluminoxane activator is a modified methylaluminoxane activator. The aluminum-containing activator may include MMAO-12. In some embodiments, the aluminum-containing activator comprises a trialkylaluminum activator; and the catalyst system further comprises a borate co-activator. The trialkylaluminum activator may comprise triisobutylaluminum. In some embodiments, the molar ratio of the aluminum-containing activator to tris[(trimethylsilyl)methyl]scandium ranges from about 20 to about 1000, from about 50 to about 500, or from about 75 to about 200. The method further comprises quenching the reaction product of the copolymerization. In some embodiments, the method further comprises drying the quenched reaction product. The reaction product may be quenched with a quenching composition containing isopropanol and butylated hydroxytoluene.

[0007]

[0004] In another embodiment, a method for producing an ethylene-butadiene copolymer is disclosed. The method includes providing a first composition containing butadiene and ethylene to a reactor; providing a second composition containing tris[(trimethylsilyl)methyl]scandium and a first aliquot of an aluminum-containing activator to the reactor; and copolymerizing the butadiene with the ethylene. The first composition may further include a second aliquot of an aluminum-containing activator. In some embodiments, the method further includes quenching a reaction product of the copolymerization; and drying the quenched reaction product. The aluminum-containing activator may include a modified aluminoxane activator; or the aluminum-containing activator may include a trialkylaluminum activator, and at least one of the first composition and the second composition may further include a borate co-activator.

[0008]

[0005] These and other non-limiting aspects and / or objectives of the present disclosure are described in more detail below.

[0009]

[0006] Below is a brief description of the drawings that are presented for the purpose of illustrating, and not for the purpose of limiting, the exemplary embodiments disclosed herein. [Brief description of the drawings]

[0010] [Figure 1] 1 is a flow chart illustrating a non-limiting example of a method for producing a catalyst composition according to some embodiments of the present disclosure. [Diagram 2] 1 is a flow chart illustrating a non-limiting example of a method for producing an ethylene-butadiene copolymer according to some embodiments of the present disclosure. [Diagram 3]

[0009] FIG. 1 is a partial side view of a non-limiting example of a tire according to some embodiments of the present disclosure. [Figure 4]1 is a flowchart illustrating a non-limiting example method of forming an article according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011]

[0011] The present disclosure may be understood more readily by reference to the following detailed description of the preferred embodiments contained therein, and the drawings in which: In the following specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings.

[0012]

[0012] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Methods and materials are described below, but similar or equivalent methods and materials can be used in the practice or testing of this disclosure. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and articles disclosed herein are merely illustrative and are not intended to be limiting.

[0013]

[0013] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0014]

[0014] The term "comprising" as used in the specification and in the claims may include "consisting of" and "consisting essentially of" embodiments. As used herein, the terms "comprise(s)", "include(s)", "having", "has", "can", "contain(s)", and variations thereof, are intended to be open-ended transitional phrases that require the presence of the named components / steps and allow for the presence of other components / steps. However, such statements should also be construed as describing compositions, mixtures, or methods that "consist of" and "consist essentially of" the recited components / steps, allowing for the presence of only the named components / steps, along with any impurities that may result from the named components / steps, and excluding other components / steps.

[0015]

[0015] Unless otherwise indicated to the contrary, numerical values ​​in this specification should be understood to include numerical values ​​that are the same when given the same number of significant digits, as well as numerical values ​​that differ from the stated value by less than the experimental error of conventional measurement techniques of the type used to determine the particular value.

[0016]

[0016] All ranges disclosed herein are inclusive of the recited endpoints and are independently combinable (e.g., the range "from 2 to 10" includes the endpoints 2 and 10 and all intermediate values). The endpoints of the ranges and any values ​​disclosed herein are not limited to the exact ranges or values; they are imprecise enough to include values ​​that are approximations of these ranges and / or values.

[0017]

[0017] Approximate language as used herein may be applied to modify any quantitative expression that may vary without resulting in a change in the basic function to which the language pertains. Thus, a value modified by one or more terms such as "about" and "substantially" may not be limited to the exact value specified in some cases. The modifier "about" should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. For example, the phrase "about 2 to about 4" also discloses a range of "2 to 4". The term "about" may refer to plus or minus 10% of the indicated numerical value. For example, "about 10%" may indicate a range of 9% to 11%, and "about 1" may mean 0.9 to 1.1.

[0018]

[0018] In the recitation of numerical ranges herein, each intervening numerical value is expressly contemplated to the same degree of precision, for example, in the range 6 to 9, the numerical values ​​7 and 8 are contemplated in addition to 6 and 9, and in the range 6.0 to 7.0, the numerical values ​​6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are expressly contemplated.

[0019]

[0019] The present disclosure relates to a process for producing ethylene-butadiene copolymers, the catalyst compositions used in the process, and articles formed from the compositions comprising the copolymers.

[0020] It has been unexpectedly discovered that the catalyst composition, when exposed to a mixture of butadiene and ethylene, is capable of producing copolymers with up to 6 mol % ethylene.

[0021] Scandium catalyst systems are the simpler and perhaps less costly class of catalysts reported in the literature.

[0022] 1 is a flow chart illustrating a non-limiting example of a method 100 for producing a catalyst composition according to some embodiments of the present disclosure. The method 100 includes dissolving tris[(trimethylsilyl)methyl]scandium in a solvent 110.

[0023]

[0023] An aluminum-containing activator and optionally a borate co-activator 120 are added. The solvent may be a hydrocarbon solvent. In some embodiments, the solvent comprises one or more aromatic, paraffinic, and / or cycloparaffinic compounds. The solvent may contain 4 to 10 carbon atoms. Non-limiting examples include butane, pentane, isooctane, cyclohexane, n-hexane, benzene, toluene, xylene, ethylbenzene, and diethylbenzene. Mixtures of two or more hydrocarbon solvents may also be utilized.

[0024]

[0024] The aluminum-containing activator may be an aluminoxane activator. The aluminoxane activator may be an alkylaluminoxane activator, such as a methylaluminoxane activator.

[0025] The aluminoxane activator may be a modified aluminoxane activator, such as a modified methylaluminoxane activator.

[0026] In some embodiments, the methylaluminoxane activator is modified by replacing a portion of the methyl groups with linear or branched alkyl groups having 3 to 10 carbon atoms. In some embodiments, 40 mol % or less (e.g., 5 to 35 mol %) of the alkyl groups may be replaced.

[0027]

[0027] Non-limiting examples of modified methylaluminoxane activators include MMAO-12, MMAO-3a, and MMAO-7.

[0028] The aluminum-containing activator may include at least an organoaluminum compound, such as a triorganoaluminum compound. The triorganoaluminum compound may be a trialkylaluminum compound.

[0029]

[0029] Non-limiting examples of aluminum-containing compounds include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum, triphenylaluminum, tri-p-tolylaluminum, tribenzylaluminum, ethyldiphenylaluminum, ethyl-di-p-tolylaluminum, ethyldibenzylaluminum, diethylphenylaluminum, diethyl-p-tolylaluminum, and diethylbenzylaluminum.

[0030] The molar ratio of the aluminum-containing activator to tris[(trimethylsilyl)methyl]scandium may range from about 20 to about 1000, from about 50 to about 500, or from about 75 to about 200.

[0031]

[0031] The borate coactivators include trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, tri(t-butyl)ammonium tetraphenylborate, N,N-dimethylanilinium tetraphenylborate, N,N-diethylanilinium tetraphenylborate, N,N-dimethylanilinium tetra-(3,5-bis(trifluoromethyl)phenyl)borate, N,N-dimethyl-(2,4,6-trimethylanilinium) tetraphenylborate, trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate, tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate, tetrakis(pentafluorophenyl)borate, tetrakis(pentafluorophenyl)borate N,N-dimethylanilinium;tetrakis(pentafluorophenyl)borate N,N-diethylanilinium;tetrakis(pentafluorophenyl)borate N,N-dimethyl-(2,4,6-trimethylanilinium);tetrakis-(2,3,4,6-tetrafluorophenyl)borate trimethylammonium;tetrakis-(2,3,4,6-tetrafluorophenyl)borate N,N-dimethylanilinium;tetrakis(pentafluorophenyl)borate di-(i-propyl) ammonium, dicyclohexylammonium tetrakis(pentafluorophenyl)borate; triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(o-tolyl)phosphonium tetrakis(pentafluorophenyl)borate, tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate; and / or N,N-dimethylanilinium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate.

[0032] The molar ratio of the aluminum-containing activator to the borate co-activator may range from about 20 to about 1000, from about 50 to about 500, or from about 75 to about 200.

[0033] The co-activator may be used stoichiometrically relative to the main metal catalyst. The molar ratio of borate co-activator to tris[(trimethylsilyl)methyl]scandium may be about 1.

[0034] 2 is a flow chart illustrating a non-limiting example of a method 201 for producing an ethylene-butadiene copolymer according to some embodiments of the present disclosure. The method 201 includes preparing a catalyst composition 200, copolymerizing ethylene and butadiene in the presence of the catalyst composition 230, quenching 240, and drying 250. The ethylene-butadiene copolymer may contain about 1 mol% to about 20 mol%, about 1 mol% to about 10 mol%, or about 1 mol% to about 7 mol% ethylene.

[0035] Optionally, a catalyst composition preparation step 200 is prepared as discussed above with respect to method 100. The catalyst composition includes tris[(trimethylsilyl)methyl]scandium, an aluminum-containing activator, and optionally a borate co-activator.

[0036] The ethylene and butadiene reacted during the copolymerization step 230 may be provided to the copolymerization reactor prior to the catalyst composition, simultaneously with the catalyst composition, and / or after the catalyst composition.

[0037] The copolymerization step 230 may include providing ethylene to the polymerization vessel containing the butadiene. The ethylene may be provided by flushing a solution containing butadiene in a solvent with ethylene. Ethylene gas may be provided to saturate the butadiene. A catalyst composition is provided to the polymerization vessel. The polymerization vessel may be heated to a temperature ranging from about 30° C. to about 150° C., from about 30° C. to about 100° C., or from about 40° C. to about 90° C., for a period ranging from about 15 minutes to about 36 hours, from about 20 minutes to about 12 hours, or from about 20 minutes to about 3 hours.

[0038]

[0038] The quenching step 240 includes providing a quenching composition to the polymerization vessel. The quenching composition may contain an acidic proton source and / or a protic quenching agent. An antioxidant may be included in the quenching composition and / or may be provided simultaneously or sequentially to the polymerization vessel. In some embodiments, the quenching composition contains isopropanol and butylated hydroxytoluene (BHT). In some embodiments, an excess of isopropanol or other protic solvent is added along with 0.1 phr to 1.0 phr, 0.25 phr to 0.75 phr, or about 0.5 phr of a stabilizer (e.g., BHT).

[0039] The drying step 250 evaporates the solvent and may be passive or active.

[0040]

[0040] Articles made using the ethylene / butadiene copolymers are also disclosed. For example, the ethylene / butadiene copolymers may be useful in making tires.

[0041]

[0041] The rubber composition may be incorporated into various rubber components of a tire. For example, the rubber component may be the tread (including the tread cap and tread base), sidewall, apex, chafer, sidewall insert, wire coat, or innerliner. In one embodiment, the component is the tread.

[0042]

[0042] The pneumatic tire may be a race tire, a passenger tire, an aircraft tire, an agricultural tire, an earthmoving tire, an off-road tire, a truck tire, and the like. In one embodiment, the tire is a passenger or truck tire. The tire may be radial or bias.

[0043]

[0043] The rubber composition may be used in other products including, but not limited to, non-pneumatic tires, belts, hoses, shoes, air springs, engine mounts, and the like.

[0044] In addition to the ethylene-butadiene copolymer, the rubber composition may optionally contain one or more rubbers or elastomers containing olefinic unsaturation. The phrase "rubber or elastomer containing olefinic unsaturation" or "diene-based elastomer" is intended to include both natural rubber and its various raw and reclaim forms, as well as various synthetic rubbers. In this description, the terms "rubber" and "elastomer" may be used interchangeably unless otherwise specified. The terms "rubber composition," "compounded rubber," and "rubber compound" are used interchangeably to refer to rubber blended or mixed with various ingredients and materials, such terms being well known to those skilled in the art of rubber mixing or compounding. Representative synthetic polymers are the homopolymerization products of butadiene and its analogs and derivatives, such as methylbutadiene, dimethylbutadiene, and pentadiene, as well as copolymers formed from butadiene or its analogs or derivatives with other unsaturated monomers. Among the latter are acetylenes, such as vinyl acetylene; olefins, such as isobutylene, which is copolymerized with isoprene to form butyl rubber; vinyl compounds, such as acrylic acid, acrylonitrile (which is copolymerized with butadiene to form NBR), methacrylic acid, and styrene, which is polymerized with butadiene to form SBR, as well as vinyl esters, and various unsaturated aldehydes, ketones, and ethers, such as acrolein, methyl isopropenyl ketone, and vinyl ethyl ether. Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), butyl rubber, halobutyl rubber such as chlorobutyl rubber or bromobutyl rubber, styrene / isoprene / butadiene rubber, copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile, and methacrylates, and ethylene / propylene terpolymers, also known as ethylene / propylene / diene monomer (EDPM), especially ethylene / propylene / dicyclopentadiene terpolymer.Additional examples of rubbers that may be used include alkoxy-silyl end-functionalized solution polymerized polymers (SBR, PBR, IBR, and SIBR), silicon-coupled and tin-coupled star-branched polymers. Preferred rubbers or elastomers are polyisoprene (natural or synthetic), polybutadiene, and SBR.

[0045] In some embodiments, the at least one additional rubber is preferably of at least two diene-based rubbers, such as cis 1,4-polyisoprene rubber (natural or synthetic, but preferably natural), 3,4-polyisoprene rubber, styrene / isoprene / butadiene rubber, emulsion and solution polymerization derived styrene / butadiene rubber, cis 1,4-polybutadiene rubber and butadiene / acrylonitrile copolymers prepared by emulsion polymerization, or a combination of two or more rubbers.

[0046] In some embodiments, emulsion polymerization derived styrene / butadiene (E-SBR) may be used having a more conventional styrene content of about 20 to about 28 percent bound styrene, or, in some applications, E-SBR having a medium to relatively high bound styrene content, i.e., about 30 to about 45 percent bound styrene.

[0047] By emulsion polymerization prepared E-SBR, it is meant that styrene and 1,3-butadiene are copolymerized as an aqueous emulsion. Such are well known to those skilled in such art. The amount of bound styrene may vary, for example, from about 5 to about 50 percent. In one embodiment, the E-SBR may contain acrylonitrile to form a terpolymer rubber as an E-SBAR, for example, in an amount of about 2 to about 30 weight percent bound acrylonitrile in the terpolymer.

[0048] Emulsion polymerization prepared styrene / butadiene / acrylonitrile copolymer rubbers containing from about 2 to about 40 weight percent bound acrylonitrile in the copolymer are also contemplated as diene based rubbers.

[0049] Solution polymerization prepared SBR (S-SBR) typically has a bound styrene content ranging from about 5 to about 50, preferably from about 9 to about 36 percent. S-SBR can be conveniently prepared, for example, by organolithium catalysis in the presence of an organic hydrocarbon solvent.

[0050] In one embodiment, cis 1,4-polybutadiene rubber (BR) may be used. Such BR may be prepared, for example, by organic solution polymerization of 1,3-butadiene. The BR may be conveniently characterized, for example, by having a cis 1,4-content of at least 90 percent.

[0051]

[0051] cis 1,4-polyisoprene and cis 1,4-polyisoprene natural rubber are well known to those having skill in the rubber art.

[0052]

[0052] The term "phr" as used herein, in accordance with conventional practice, refers to "parts by weight of a respective material per 100 parts by weight of rubber or elastomer."

[0053] The rubber composition may contain up to 70 phr of processing oil. The processing oil may be included in the rubber composition as an extending oil typically used to extend the elastomer. The processing oil may be included in the rubber composition by adding the oil directly during rubber compounding. The processing oil used may include both the extending oil present in the elastomer and the processing oil added during compounding. Suitable processing oils include various oils known in the art, including aromatic, paraffinic, naphthenic, vegetable oils, and low PCA oils, such as MES, TDAE, SRAE, and heavy naphthenic oils. Suitable low PCA oils include those having a polycyclic aromatic content of less than 3 weight percent as determined by the IP346 method. The procedure for the IP346 method can be found in Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000 Parts, 2003, 62nd Edition, published by the Institute of Petroleum, United Kingdom.

[0054] The rubber composition may contain from about 10 to about 150 phr of silica. In another embodiment, from 20 to 80 phr of silica may be used.

[0055]

[0055] Commonly used siliceous pigments that can be used in rubber compounds include conventional pyrogenic and precipitated siliceous pigments (silica). In one embodiment, precipitated silicas are used. The conventional siliceous pigments used are precipitated silicas, such as those obtained by acidification of soluble silicates, e.g. sodium silicate.

[0056] Such conventional silicas may be characterized, for example, by having a BET (Brunauer-Emmett-Teller) surface area, as measured using nitrogen gas. In one embodiment, the BET surface area may range from about 40 to about 600 square meters per gram. In another embodiment, the BET surface area may range from about 80 to about 300 square meters per gram. The BET method of measuring surface area is described in the Journal of the American Chemical Society, Vol. 60, p. 304 (1930).

[0057] Conventional silicas may be characterized as having a dibutyl phthalate (DBP) absorption value ranging from about 100 to about 400, alternatively from about 150 to about 300.

[0058]

[0058] Conventional silica can be expected to have an average ultimate particle size in the range of 0.01 to 0.05 microns as determined, for example, by electron microscopy, although the silica particles may be smaller or possibly larger in size.

[0059]

[0059] Various commercially available silicas may be used, such as, by way of example only and without limitation herein, silicas commercially available from PPG Industries under the Hi-Sil trademark designated 210, 243, etc.; silicas available from Rhodia designated, for example, Z1165MP and Z165GR, and silicas available from Degussa AG designated, for example, VN2 and VN3.

[0060]

[0060] Commonly used carbon blacks can be used as conventional fillers in amounts ranging from 10 to 150 phr. In another embodiment, 20 to 80 phr of carbon black may be used. Representative examples of such carbon blacks include N110, N121, N134, N220, N231, N234, N242, N293, N299, N315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990, and N991. These carbon blacks have iodine absorptions ranging from 9 to 145 g / kg and iodine concentrations ranging from 34 to 150 cm 3 It has a DBP value of up to / 100g.

[0061] Other fillers may be used in the rubber composition, including, but not limited to, particulate fillers including ultra-high molecular weight polyethylene (UHMWPE), crosslinked particulate polymer gels including, but not limited to, those disclosed in U.S. Patent Nos. 6,242,534; 6,207,757; 6,133,364; 6,372,857; 5,395,891; or 6,127,488, and plasticized starch composite fillers including, but not limited to, those disclosed in U.S. Patent No. 5,672,639. The aforementioned patents are incorporated herein by reference in their entirety. Such other fillers may be used in amounts ranging from 1 to 30 phr.

[0062] In some embodiments, the rubber composition may contain a conventional sulfur-containing organosilicon compound. In one embodiment, the sulfur-containing organosilicon compound is 3,3'-bis(trimethoxy or triethoxysilylpropyl) polysulfide. In one embodiment, the sulfur-containing organosilicon compound is 3,3'-bis(triethoxysilylpropyl) disulfide and / or 3,3'-bis(triethoxysilylpropyl) tetrasulfide.

[0063]

[0063] In some embodiments, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent No. 6,608,125. In one embodiment, the sulfur-containing organosilicon compound includes 3-(octanoylthio)-1-propyltriethoxysilane, CH3(CH2)6C(=O)-S-CH2CH2CH2Si(OCH2CH3)3 (commercially available as NXT™ from Momentive Performance Materials).

[0064]

[0064] In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent Publication No. 2003 / 0130535, the entirety of which is incorporated herein by reference. In one embodiment, the sulfur-containing organosilicon compound is Si-363 manufactured by Degussa.

[0065] The amount of the sulfur-containing organosilicon compound in the rubber composition will vary depending on the level of other additives used. Generally, the amount of the compound will range from 0.5 to 20 phr. In one embodiment, the amount will range from 1 to 10 phr.

[0066]

[0066] It will be readily understood by those skilled in the art that the rubber composition may be compounded by methods generally known in the art of rubber compounding, such as mixing various sulfur-vulcanizable component rubbers with various commonly used additive materials, such as sulfur donors, curing aids, such as activators and retarders, processing additives, such as oils, resins including tackifying resins, and plasticizers, fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants, and antiozonants, and peptizers. Depending on the sulfur vulcanizability and the intended use of the sulfur-vulcanized material (rubber), as known to those skilled in the art, the above-mentioned additives are selected and generally used in conventional amounts. Representative examples of sulfur donors include elemental sulfur (free sulfur), amine disulfides, polymeric polysulfides, and sulfur olefin adducts. In one embodiment, the sulfur-vulcanizing agent is elemental sulfur. The sulfur-vulcanizing agent may be used in an amount ranging from 0.5 to 8 phr, or in a range of 1.5 to 6 phr. A typical amount of tackifying resin, if used, comprises about 0.5 to about 10 phr, usually about 1 to about 5 phr. A typical amount of processing aid comprises about 1 to about 50 phr. A typical amount of antioxidant comprises about 1 to about 5 phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others, such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344 to 346. A typical amount of antiozonant comprises about 1 to 5 phr. A typical amount of fatty acid, which may include stearic acid, if used, comprises about 0.5 to about 3 phr. A typical amount of zinc oxide comprises about 2 to about 5 phr. A typical amount of wax comprises about 1 to about 5 phr. Often, microcrystalline wax is used. A typical amount of peptizer comprises about 0.1 to about 1 phr. Typical peptizers may be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

[0067] Accelerators are used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanizate. In one embodiment, a single accelerator system may be used, i.e., a primary accelerator. The primary accelerator(s) may be used in a total amount ranging from about 0.5 to about 4, or alternatively from about 0.8 to about 1.5 phr. In another embodiment, a combination of primary and secondary accelerators may be used, with the secondary accelerator being used in a smaller amount, for example, from about 0.05 to about 3 phr, to activate the vulcanizate and improve its properties. These accelerator combinations may be expected to produce a synergistic effect on the final properties, somewhat better than those produced by the use of either accelerator alone. Additionally, delayed-acting accelerators may be used that produce a satisfactory cure at normal vulcanization temperatures without being affected by normal processing temperatures. Vulcanization retarders may also be used. Suitable accelerator types that may be used include amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates, and xanthates. In one embodiment, if a second accelerator is used, the primary accelerator is a sulfenamide and the secondary accelerator may be a guanidine, dithiocarbamate, or thiuram compound.

[0068]

[0068] The mixing of the rubber composition can be accomplished by methods known to those skilled in the rubber mixing art. For example, the components are typically mixed in at least two stages, namely, at least one non-productive stage followed by a productive mix stage. The final curatives, including sulfur-vulcanizing agents, are typically mixed in the final stage, conventionally referred to as the "productive" mix stage, in which mixing typically occurs at a lower temperature than the mixing temperature(s) in the preceding non-productive mix stage(s) or at a final temperature. The terms "non-productive" and "productive" mix stages are well known to those skilled in the rubber mixing art. The rubber composition may be subjected to a thermomechanical mixing step. The thermomechanical mixing step generally involves mechanical work in a mixer or extruder for a suitable period of time to bring the rubber temperature between 140°C and 190°C. The suitable duration of the thermomechanical work varies as a function of the operating conditions and the volume and nature of the components. For example, the thermomechanical work may be from 1 to 20 minutes.

[0069]

[0069] The rubber composition may be incorporated into various rubber components of a tire. For example, the rubber component may be the tread (including the tread cap and tread base), sidewall, apex, chafer, sidewall insert, wire coat, or innerliner. In one embodiment, the component is the tread.

[0070]

[0070] The pneumatic tire may be a race tire, a passenger tire, an aircraft tire, an agricultural tire, an earthmoving tire, an off-road tire, a truck tire, and the like. In one embodiment, the tire is a passenger or truck tire. The tire may be radial or bias.

[0071]

[0071] The rubber composition may be used in other products including, but not limited to, non-pneumatic tires, belts, hoses, shoes, air springs, engine mounts, and the like.

[0072]

[0072] Vulcanization of pneumatic tires may be carried out at conventional temperatures ranging from about 100°C to 200°C. In one embodiment, vulcanization is carried out at a temperature ranging from about 110°C to 180°C. Any of the usual vulcanization processes may be used, such as heating in a press or mold, heating with superheated steam or hot air, etc. Such tires can be built, shaped, molded, and cured by a variety of methods that are known and readily apparent to those skilled in such art.

[0073]

[0073] Figure 3 is a partial side view of a non-limiting example of a tire 301 according to some embodiments of the present disclosure. The tire 301 includes a tread portion 302, a bead portion 303, and a sidewall portion 304 positioned between the tread portion 302 and the bead portion 303. The tread portion 302, the bead portion 303, and the sidewall portion 304 of a tire according to the present disclosure are not limited to the specific configuration shown in Figure 3. For example, there may be multiple sidewall portions, ribs, patterns, colors, etc. Figure 3 is provided to illustrate one example of where a composition containing a copolymer produced by the method of the present disclosure may be utilized. The copolymer may be utilized in one or more of the tread portion 302, the bead portion 303, and the sidewall portion 304.

[0074] 4 is a flow chart illustrating a non-limiting example of a method 455 for forming an article (e.g., a tire) according to some embodiments of the present disclosure. The method 455 includes a step 460 of providing a composition containing an ethylene-butadiene copolymer, a non-productive mix step 470, a productive mix step 480, and a vulcanization step 490.

[0075] The following examples are provided to illustrate the devices and methods of the present disclosure. The examples are merely illustrative and are not intended to limit the disclosure to the materials, conditions, or process parameters previously described herein. EXAMPLES

[0076] A butadiene premix was prepared in toluene (15 wt%) and dried over a column of dry alumina / sieves. The premix was charged into a 4 oz Boston round bottle. The solution was saturated with ethylene gas by flushing with a stream of ethylene for about 5 minutes. A catalyst solution was prepared in toluene under an inert atmosphere by dissolving 7.4 mg (0.0164 mmol) of tris[(trimethylsilyl)methyl]scandium (CAS 872992-17-1) in 2 mL of toluene, followed by the addition of MMAO-12 (100 equiv., 1.64 mmol, 1.52 mL of a 7% solution). An additional aliquot of MMAO-12 (100 equiv., 1.64 mmol, 1.52 mL of a 7% solution) was charged into the polymerization vessel, followed by the entirety of the scandium catalyst solution. The bottle was heated to 50° C. for 3 hours, then quenched with an isopropanol / BHT solution and evaporated to remove the solvent. The resulting polymer was analyzed by 1H NMR and 13C NMR to determine the ethylene incorporation. By 13C NMR, the polymer was found to be 62% cis, 33% trans, and 5% vinyl. The ethylene incorporation measured by 1H NMR was found to be 7.4 mol%.

[0077]

[0077] This written description uses examples to describe the present disclosure, including the best mode, and to enable one of ordinary skill in the art to make and use the present disclosure. Other examples that occur to those of ordinary skill in the art are intended to be within the scope of the present disclosure if they have structural elements that do not differ from the same concept or include equivalent structural elements with insubstantial differences. It will be understood that the above-disclosed and other features and functions, or alternatives thereof, may be combined with many other different systems or applications. Various, currently unforeseen or unanticipated alternatives, modifications, variations, or improvements thereon may continue to be made by those of ordinary skill in the art, which are also intended to be encompassed by the following claims.

Claims

1. 1. A process for producing an ethylene-butadiene copolymer, comprising: Tris[(trimethylsilyl)methyl]scandium, and Aluminum-containing activators copolymerizing butadiene with ethylene in the presence of a catalyst system comprising A method comprising:

2. The method of claim 1 , wherein the catalyst system further comprises a borate coactivator.

3. The method of claim 2, wherein the borate co-activator comprises tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and / or tetrakis(pentafluorophenyl)borate.

4. The method of claim 1 , wherein the aluminum-containing activator is an aluminoxane activator.

5. The method of claim 4 , wherein the aluminoxane activator is a modified aluminoxane activator.

6. The method of claim 4, wherein the aluminoxane activator is a methylaluminoxane activator.

7. 7. The method of claim 6, wherein the methylaluminoxane activator is a modified methylaluminoxane activator.

8. The method of claim 1 , wherein the aluminum-containing activator comprises MMAO-12.

9. 10. The method of claim 1, wherein the aluminum-containing activator comprises a trialkylaluminum activator and the catalyst system further comprises a borate co-activator.

10. 10. The method of claim 9, wherein the trialkylaluminum activator comprises triisobutylaluminum.

11. The method of claim 9, wherein the borate co-activator comprises tetrakis(3,5-bis(trifluoromethyl)phenyl)borate.

12. 10. The method of claim 9, wherein the borate co-activator comprises tetrakis(pentafluorophenyl)borate.

13. 2. The method of claim 1, wherein the molar ratio of the aluminum-containing activator to tris[(trimethylsilyl)methyl]scandium is in the range of about 20 to about 1000.

14. quenching the reaction product of the copolymerization. The method of claim 1 further comprising:

15. Drying the quenched reaction product. The method of claim 14 further comprising:

16. 15. The method of claim 14, wherein the reaction product is quenched with a quenching composition comprising isopropanol and butylated hydroxytoluene.

17. 1. A process for producing an ethylene-butadiene copolymer, comprising: providing a first composition comprising butadiene and ethylene to a reactor; providing a second composition comprising a first aliquot of a tris[(trimethylsilyl)methyl]scandium and aluminum-containing activator to the reactor; copolymerizing butadiene with ethylene; A method comprising:

18. 20. The method of claim 17, wherein the first composition further comprises a second aliquot of the aluminum-containing activator.

19. quenching the reaction product of the copolymerization; drying the quenched reaction product; 20. The method of claim 17, further comprising:

20. (a) the aluminum-containing activator comprises a modified aluminoxane activator; or (b) the aluminum-containing activator comprises a trialkylaluminum activator, and at least one of the first composition and the second composition further comprises a borate co-activator; 20. The method of claim 17.

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