cis-1,4-Polybutadiene with Improved Cold Flow Resistance

Abstract

To provide a method for preparing cis-1,4-polydienes having useful resistance to a cold flow.SOLUTION: The method comprises the steps of: (i) preparing a polymerization system including a reactive polymer by introducing a lanthanide-based catalyst and a conjugated diene monomer, and ii) adding a Lewis acid to the polymerization system including the reactive polymer. The step (ii) is performed at 20°C-100°C. The Lewis acid and the reactive polymer are aged for at least 5 minutes prior to any quenching of the polymerization system. The Lewis acid is selected from the group consisting of titanium tetraalkoxides, boron trifluoride, trihydrocarbyl boranes, trihydrocarbyloxy borates, trihydrocarbylsilyl halides, trihydrocarbylsilyl triflates, titanium tetrahalides, aluminum trihalides and zinc dihalides.SELECTED DRAWING: None

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 108,883, filed on January 28, 2015; U.S. Provisional Patent Application No. 62 / 108,839, filed on January 28, 2015; and U.S. Provisional Patent Application No. 62 / 108,899, filed on January 28, 2015, the disclosures of which are incorporated herein by reference.

[0002] Embodiments of the present invention relate to cis-1,4-polybutadiene having improved cold flow properties. The polybutadiene is prepared using a lanthanide-based catalyst and treated with a Lewis acid.

Background Art

[0003] Lanthanide-based catalyst systems are known to be useful for polymerizing conjugated diene monomers to form polybutadienes having a high cis-1,4-bond content, a low 1,2-bond content, and a linear backbone. This cis-1,4-polybutadiene containing a linear backbone is considered to provide better tensile properties, higher abrasion resistance, lower hysteresis, and better fatigue resistance compared to cis-1,4-polybutadienes prepared using other catalyst systems (e.g., titanium-based, cobalt-based, and nickel-based catalyst systems). Therefore, cis-1,4-polybutadiene produced using a lanthanide-based catalyst is particularly suitable for use in tire components (e.g., sidewalls and treads).

[0004] However, a disadvantage of cis-1,4-polybutadiene prepared using a lanthanide-based catalyst is that the polymer may exhibit high cold flow because it has a linear backbone structure. High cold flow causes problems during storage and transportation of the polymer and also hinders the use of automatic feeding devices in rubber compound mixing facilities.

[0005] When synthesized using a lanthanide-based catalyst system, cis-1,4-polybutadiene can exhibit pseudo-living characteristics in that, upon completion of polymerization, some polymer chains possess reactive ends that can react with specific functionalizing agents to yield functionalized cis-1,4-polybutadiene. These functionalizing agents have been used to improve the cold flow resistance of the resulting polybutadiene. However, whether a specific functional group imparted to the polymer can improve cold flow resistance or reduce hysteresis is often unpredictable in many cases. Furthermore, a functionalizing agent effective for one type of polymer is not necessarily effective for another type of polymer, and vice versa.

[0006] Therefore, there is a need to develop a process for producing functionalized cis-1,4-polybutadiene having a combination of high cis content, a linear backbone, and improved cold flow resistance. This combination of polymer properties provides tires with excellent performance.

SUMMARY OF THE INVENTION

[0007] One or more embodiments of the present invention are methods for preparing cis-1,4-polybutadiene having useful resistance to cold flow, comprising the steps of preparing a polymerization system comprising a reactive polymer by introducing a lanthanide-based catalyst and a conjugated diene monomer, and adding a Lewis acid to the polymerization system comprising the reactive polymer.

[0008] Another embodiment of the present invention provides a vulcanizable composition comprising a filler, a curing agent, and cis-1,4-polybutadiene prepared by a method comprising the steps of polymerizing a conjugated diene monomer using a lanthanide-based catalyst to form a reactive polymer, and treating the reactive polymer with a Lewis acid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]

Figure 1

[0010]

Figure 2

Best Mode for Carrying Out the Invention

[0011] Embodiments of the present invention are at least partially based on finding a method for producing cis-1,4-polydiene having technically useful resistance to cold flow. According to an aspect of the present invention, cis-1,4-polydiene having reactive chain ends is prepared from a conjugated diene monomer and then treated with a Lewis acid before quenching the polymer. Without being bound by any particular theory, it is believed that by treating the cis-1,4-polydiene before quenching the polymer, the polymer chains are at least partially bonded or networked, thereby obtaining the desired cold flow resistance. Further, it has been confirmed that while the cold flow resistance of the polymer is improved, the Mooney viscosity of the polymer is not adversely affected, particularly at high shear. Further, in vulcanized rubber prepared using cis-1,4-polydiene of one or more embodiments, the properties are improved (e.g., the hysteresis loss is reduced). Monomer

[0012] Examples of conjugated diene monomers include 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 2,4-hexadiene. A mixture of two or more conjugated dienes may be used in the copolymerization. Catalyst system

[0013] In one or more embodiments, the catalyst system used in the present invention is a coordination catalyst system. In certain embodiments, this coordination catalyst system is a lanthanide-based catalyst system. In one or more embodiments, this catalyst system is a pre-formed lanthanide-based catalyst system. In other embodiments, this catalyst system is a lanthanide-based catalyst system formed in situ. Coordination catalyst system

[0014] Coordination catalyst systems are generally known. Important mechanistic features of coordination polymerization are described in books (e.g., Kuran, W., Principles of Coordination Polymerization; John Wiley & Sons: New York, 2001) and reviews (e.g., Mulhaupt, R., Macromolecular Chemistry and Physics 2003, volume 204, pages 289 - 327). The mechanism by which a coordination catalyst initiates the polymerization of a monomer is thought to involve the coordination or complexation of the monomer to the active metal center prior to insertion of the monomer into the growing polymer chain. Coordination catalysts have the beneficial feature that they can produce stereoregular polymers by stereochemically controlling the polymerization. As is known in the art, there are numerous methods for forming coordination catalysts. However, all methods ultimately generate an active intermediate that can coordinate with a monomer and insert the monomer into a covalent bond between the active metal center and the growing polymer chain. The coordination polymerization of conjugated dienes is thought to proceed via π-allyl complexes as intermediates. Coordination catalysts can be one-component, two-component, three-component, or multi-component systems. In one or more embodiments, the formation of a coordination catalyst may be carried out by combining a heavy metal compound (e.g., a transition metal compound or a lanthanide-containing compound), an alkylating agent (e.g., an organoaluminum compound), and optionally other cocatalyst components (e.g., a Lewis acid or a Lewis base). In one or more embodiments, the heavy metal compound may be referred to as a coordination metal compound. Lanthanide-based catalyst system

[0015] The practice of the present invention is not necessarily limited to selecting a specific lanthanide catalyst system. In one or more embodiments, the catalyst system used comprises (a) a lanthanide-containing compound, (b) an alkylating agent, and (c) a halogen source. In other embodiments, instead of a halogen source, a compound containing a non-coordinating anion or a non-coordinating anion precursor can be used. In these or other embodiments, other organometallic compounds, Lewis bases, and / or catalyst modifiers can be used in addition to the aforementioned components or ingredients. For example, in one embodiment, a nickel-containing compound can be used as a molecular weight regulator as disclosed in U.S. Patent No. 6,699,813, which is hereby incorporated by reference in its entirety. Lanthanide-containing compound

[0016] As described above, the lanthanide catalyst system used in the present invention can include a lanthanide-containing compound. Lanthanide-containing compounds useful in the present invention are compounds containing at least one atom of lanthanum, neodymium, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and didymium. In one embodiment, these compounds can include neodymium, lanthanum, samarium, or didymium. As used herein, the term "didymium" shall refer to a commercially available mixture of rare earth elements obtained from monazite sand. In addition, the lanthanide-containing compounds useful in the present invention can be in the form of elemental lanthanides.

[0017] The lanthanide atoms in the lanthanide-containing compound may be in various oxidation states, for example, but not limited to, oxidation states of 0, +2, +3, and +4. In one embodiment, a trivalent lanthanide-containing compound (wherein the lanthanide atom is in an oxidation state of +3) can be used. Suitable lanthanide-containing compounds include, but are not limited to, lanthanide carboxylates, lanthanide organic phosphates, lanthanide organic phosphonates, lanthanide organic phosphinates, lanthanide carbamates, lanthanide dithiocarbamates, lanthanide xanthates, lanthanide β-diketonates, lanthanide alkoxides or aryloxides, lanthanide halides, lanthanide pseudohalides, lanthanide oxyhalides, and organolanthanide compounds.

[0018] In one or more embodiments, the lanthanide-containing compound may be soluble in a hydrocarbon solvent (e.g., an aromatic hydrocarbon, an aliphatic hydrocarbon, or an alicyclic hydrocarbon). However, hydrocarbon-insoluble lanthanide-containing compounds may also be useful in the present invention, because they can be suspended in the polymerization medium to form catalytic active species.

[0019] For the sake of simplicity of explanation, in a further description of useful lanthanide-containing compounds, the focus is on neodymium compounds, but those skilled in the art will be able to select similar compounds based on other lanthanide metals.

[0020] Suitable neodymium carboxylates include, but are not limited to, neodymium formate, neodymium acetate, neodymium acrylate, neodymium methacrylate, neodymium valerate, neodymium gluconate, neodymium citrate, neodymium fumarate, neodymium lactate, neodymium maleate, neodymium oxalate, neodymium 2-ethylhexanoate, neodymium neodecanoate (also known as neodymium versatate), neodymium naphthenate, neodymium stearate, neodymium oleate, neodymium benzoate, and neodymium picolinate.

[0021] Suitable neodymium organic phosphates include, but are not limited to, neodymium dibutyl phosphate, neodymium dipentyl phosphate, neodymium dihexyl phosphate, neodymium diheptyl phosphate, neodymium dioctyl phosphate, neodymium bis(1-methylheptyl) phosphate, neodymium bis(2-ethylhexyl) phosphate, neodymium didecyl phosphate, neodymium didodecyl phosphate, neodymium dioctadecyl phosphate, neodymium dioleyl phosphate, neodymium diphenyl phosphate, neodymium bis(p-nonylphenyl) phosphate, neodymium butyl(2-ethylhexyl) phosphate, neodymium(1-methylheptyl)(2-ethylhexyl) phosphate, and neodymium(2-ethylhexyl)(p-nonylphenyl) phosphate.

[0022] Suitable neodymium organic phosphonates include, but are not limited to, neodymium butyl phosphonate, neodymium pentyl phosphonate, neodymium hexyl phosphonate, neodymium heptyl phosphonate, neodymium octyl phosphonate, neodymium (1-methylheptyl) phosphonate, neodymium (2-ethylhexyl) phosphonate, neodymium decyl phosphonate, neodymium dodecyl phosphonate, neodymium octadecyl phosphonate, neodymium oleyl phosphonate, neodymium phenyl phosphonate, neodymium (p-nonylphenyl) phosphonate, neodymium butyl butyl phosphonate, neodymium pentyl pentyl phosphonate, neodymium hexyl hexyl phosphonate, neodymium heptyl heptyl phosphonate, neodymium octyl octyl phosphonate, neodymium (1-methylheptyl) (1-methylheptyl) phosphonate, neodymium (2-ethylhexyl) (2-ethylhexyl) phosphonate, neodymium decyl decyl phosphonate, neodymium dodecyl dodecyl phosphonate, neodymium octadecyl octadecyl phosphonate, neodymium oleyl oleyl phosphonate, neodymium phenyl phenyl phosphonate, neodymium (p-nonylphenyl) (p-nonylphenyl) phosphonate, neodymium butyl (2-ethylhexyl) phosphonate, neodymium (2-ethylhexyl) butyl phosphonate, neodymium (1-methylheptyl) (2-ethylhexyl) phosphonate, neodymium (2-ethylhexyl) (1-methylheptyl) phosphonate, neodymium (2-ethylhexyl) (p-nonylphenyl) phosphonate, and neodymium (p-nonylphenyl) (2-ethylhexyl) phosphonate.

[0023] Suitable neodymium organic phosphinates include, but are not limited to, neodymium butyl phosphinate, neodymium pentyl phosphinate, neodymium hexyl phosphinate, neodymium heptyl phosphinate, neodymium octyl phosphinate, neodymium (1-methylheptyl) phosphinate, neodymium (2-ethylhexyl) phosphinate, neodymium decyl phosphinate, neodymium dodecyl phosphinate, neodymium octadecyl phosphinate, neodymium oleyl phosphinate, neodymium phenyl phosphinate, neodymium (p-nonylphenyl) phosphinate, neodymium dibutyl phosphinate, neodymium dipentyl phosphinate, neodymium dihexyl phosphinate, neodymium diheptyl phosphinate, neodymium dioctyl phosphinate, neodymium bis(1-methylheptyl) phosphinate, neodymium bis(2-ethylhexyl) phosphinate, neodymium didodecyl phosphinate, neodymium dioctadecyl phosphinate, neodymium dioleyl phosphinate, neodymium diphenyl phosphinate, neodymium bis(p-nonylphenyl) phosphinate, neodymium butyl(2-ethylhexyl) phosphinate, neodymium (1-methylheptyl)(2-ethylhexyl) phosphinate, and neodymium (2-ethylhexyl)(p-nonylphenyl) phosphinate.

[0024] Suitable neodymium carbamates include, but are not limited to, neodymium dimethylcarbamate, neodymium diethylcarbamate, neodymium diisopropylcarbamate, neodymium dibutylcarbamate, and neodymium dibenzylcarbamate.

[0025] Suitable neodymium dithiocarbamates include, but are not limited to, neodymium dimethyldithiocarbamate, neodymium diethyldithiocarbamate, neodymium diisopropyldithiocarbamate, neodymium dibutyldithiocarbamate, and neodymium dibenzyldithiocarbamate.

[0026] Suitable neodymium xanthates include, but are not limited to, neodymium methyl xanthate, neodymium ethyl xanthate, neodymium isopropyl xanthate, neodymium butyl xanthate, and neodymium benzyl xanthate.

[0027] Suitable neodymium β-diketonates include, but are not limited to, neodymium acetylacetonate, neodymium trifluoroacetylacetonate, neodymium hexafluoroacetylacetonate, neodymium benzoylacetonate, and neodymium 2,2,6,6-tetramethyl-3,5-heptanedionate.

[0028] Suitable neodymium alkoxides or aryloxides include, but are not limited to, neodymium methoxide, neodymium ethoxide, neodymium isopropoxide, neodymium 2-ethylhexoxide, neodymium phenoxide, neodymium nonylphenoxide, and neodymium naphthoxide.

[0029] Suitable neodymium halides include, but are not limited to, neodymium fluoride, neodymium chloride, neodymium bromide, and neodymium iodide. Suitable neodymium pseudohalides include, but are not limited to, neodymium cyanide, neodymium cyanate, neodymium thiocyanate, neodymium azide, and neodymium ferrocyanide. Suitable neodymium oxyhalides include, but are not limited to, neodymium oxyfluoride, neodymium oxychloride, and neodymium oxybromide. A Lewis base (e.g., tetrahydrofuran (“THF”)) may be used to facilitate solubilization of this class of neodymium compounds in an inert organic solvent. When using a lanthanide halide, lanthanide oxyhalide, or other lanthanide-containing compound containing a halogen atom, the lanthanide-containing compound may optionally provide all or part of the halogen source in the lanthanide-based catalyst system.

[0030] As used herein, the term "organolanthanide compound" refers to any lanthanide-containing compound that contains at least one lanthanide-carbon bond. These compounds mainly, but not exclusively, include compounds containing cyclopentadienyl ("Cp"), substituted cyclopentadienyl, allyl, and substituted allyl ligands. Suitable organolanthanide compounds include, but are not limited to, Cp3Ln, Cp2LnR, Cp2LnCl, CpLnCl2, CpLn(cyclooctatetraene), (C5Me5)2LnR, LnR3, Ln(allyl)3, and Ln(allyl)2Cl (where Ln represents a lanthanide atom and R represents a hydrocarbyl group). In one or more embodiments, the hydrocarbyl groups useful in the present invention may contain heteroatoms such as nitrogen atoms, oxygen atoms, boron atoms, silicon atoms, sulfur atoms, and phosphorus atoms, etc. alkylating agent

[0031] As described above, the lanthanide-based catalyst system used in the present invention can include an alkylating agent. In one or more embodiments, the alkylating agent (which may also be referred to as a hydrocarbylating agent) includes an organometallic compound capable of transferring one or more hydrocarbyl groups to another metal. Generally, these agents include organometallic compounds of positive metals, such as Group 1, Group 2, and Group 3 metals (Group IA, Group IIA, and Group IIIA metals). Alkylating agents useful in the present invention include, but are not limited to, organoaluminum compounds and organomagnesium compounds. As used herein, the term "organoaluminum compound" refers to any aluminum compound containing at least one aluminum-carbon bond. In one or more embodiments, an organoaluminum compound soluble in a hydrocarbon solvent can be used. As used herein, the term "organomagnesium compound" refers to any magnesium compound containing at least one magnesium-carbon bond. In one or more embodiments, an organomagnesium compound soluble in a hydrocarbon can be used. As will be described in detail later, some species of suitable alkylating agents can be in the form of halides. When the alkylating agent contains a halogen atom, the alkylating agent may also function as all or part of the halogen source in the aforementioned catalyst system. Organoaluminum compound

[0032] In one or more embodiments, the organoaluminum compounds that can be used in the lanthanide-based catalyst system have the general formula AlR n X 3-n(In the formula, each R may independently be a monovalent organic group bonded to an aluminum atom via a carbon atom, each X may independently be a hydrogen atom, a halogen atom, a carboxylate group, an alkoxide group, or an aryloxide group, and n may be an integer in the range of 1 to 3) is included. In one or more embodiments, each R may independently be a hydrocarbyl group, such as, for example, an alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an alkenyl group, a cycloalkenyl group, a substituted cycloalkenyl group, an aryl group, a substituted aryl group, an aralkyl group, an alkaryl group, an allyl group, and an alkynyl group, and each group contains from 1 carbon atom (or the minimum number of carbon atoms appropriate to form the group) up to about 20 carbon atoms. These hydrocarbyl groups may contain heteroatoms, such as, but not limited to, nitrogen atoms, oxygen atoms, boron atoms, silicon atoms, sulfur atoms, and phosphorus atoms.)

[0033] General formula AlR n X 3-n The types of organoaluminum compounds represented by include, but are not limited to, trihydrocarbylaluminum, dihydrocarbylaluminum hydride, hydrocarbylaluminum dihydride, dihydrocarbylaluminum carboxylate, hydrocarbylaluminum bis(carboxylate), dihydrocarbylaluminum alkoxide, hydrocarbylaluminum dialkoxide, dihydrocarbylaluminum halide, hydrocarbylaluminum dihalide, dihydrocarbylaluminum aryloxide, and hydrocarbylaluminum diaryloxide compounds. In one embodiment, the alkylating agent can include trihydrocarbylaluminum, dihydrocarbylaluminum hydride, and / or hydrocarbylaluminum dihydride compounds. In one embodiment, when the alkylating agent includes an organoaluminum hydride compound, the aforementioned halogen source can be provided by a tin halide, which is disclosed in U.S. Patent No. 7,008,899, which is hereby incorporated by reference in its entirety.)

[0034] Suitable trihydrocarbyl aluminum compounds include, but are not limited to, trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tri-n-propyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, tri-t-butyl aluminum, tri-n-pentyl aluminum, trineopentyl aluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum, tris(2-ethylhexyl) aluminum, tricyclohexyl aluminum, tris(1-methylcyclopentyl) aluminum, triphenyl aluminum, tri-p-tolyl aluminum, tris(2,6-dimethylphenyl) aluminum, tribenzyl aluminum, diethylphenyl aluminum, diethyl-p-tolyl aluminum, diethylbenzyl aluminum, ethyldiphenyl aluminum, ethyldi-p-tolyl aluminum, and ethyldibenzyl aluminum.

[0035] Suitable dihydrocarbyl aluminum hydride compounds include, but are not limited to, diethyl aluminum hydride, di-n-propyl aluminum hydride, diisopropyl aluminum hydride, di-n-butyl aluminum hydride, diisobutyl aluminum hydride, di-n-octyl aluminum hydride, diphenyl aluminum hydride, di-p-tolyl aluminum hydride, dibenzyl aluminum hydride, phenylethyl aluminum hydride, phenyl-n-propyl aluminum hydride, phenylisopropyl aluminum hydride, phenyl-n-butyl aluminum hydride, phenylisobutyl aluminum hydride, phenyl-n-octyl aluminum hydride, p-tolylethyl aluminum hydride, p-tolyl-n-propyl aluminum hydride, p-tolylisopropyl aluminum hydride, p-tolyl-n-butyl aluminum hydride, p-tolylisobutyl aluminum hydride, p-tolyl-n-octyl aluminum hydride, benzylethyl aluminum hydride, benzyl-n-propyl aluminum hydride, benzylisopropyl aluminum hydride, benzyl-n-butyl aluminum hydride, benzylisobutyl aluminum hydride, and benzyl-n-octyl aluminum hydride.

[0036] Suitable hydrocarbyl aluminum dihydrides include, but are not limited to, ethyl aluminum dihydride, n-propyl aluminum dihydride, isopropyl aluminum dihydride, n-butyl aluminum dihydride, isobutyl aluminum dihydride, and n-octyl aluminum dihydride.

[0037] Suitable dihydrocarbyl aluminum halide compounds include, but are not limited to, diethylaluminum chloride, di-n-propylaluminum chloride, diisopropylaluminum chloride, di-n-butylaluminum chloride, diisobutylaluminum chloride, di-n-octylaluminum chloride, diphenylaluminum chloride, di-p-tolylaluminum chloride, dibenzylaluminum chloride, phenylethylaluminum chloride, phenyl-n-propylaluminum chloride, phenylisopropylaluminum chloride, phenyl-n-butylaluminum chloride, phenylisobutylaluminum chloride, phenyl-n-octylaluminum chloride, p-tolylethylaluminum chloride, p-tolyl-n-propylaluminum chloride, p-tolylisopropylaluminum chloride, p-tolyl-n-butylaluminum chloride, p-tolylisobutylaluminum chloride, p-tolyl-n-octylaluminum chloride, benzylethylaluminum chloride, benzyl-n-propylaluminum chloride, benzylisopropylaluminum chloride, benzyl-n-butylaluminum chloride, benzylisobutylaluminum chloride, and benzyl-n-octylaluminum chloride.

[0038] Suitable hydrocarbyl aluminum dihalide compounds include, but are not limited to, ethylaluminum dichloride, n-propylaluminum dichloride, isopropylaluminum dichloride, n-butylaluminum dichloride, isobutylaluminum dichloride, and n-octylaluminum dichloride.

[0039] General formula AlR n X 3-nOther organoaluminum compounds useful as alkylating agents that can be represented by include dimethylaluminum hexanoate, diethylaluminum octoate, diisobutylaluminum 2-ethylhexanoate, dimethylaluminum neodecanoate, diethylaluminum stearate, diisobutylaluminum oleate, methylaluminum bis(hexanoate), ethylaluminum bis(octoate), isobutylaluminum bis(2-ethylhexanoate), methylaluminum bis(neodecanoate), ethylaluminum bis(stearate), isobutylaluminum bis(oleate), dimethylaluminum methoxide, diethylaluminum methoxide, diisobutylaluminum methoxide, dimethylaluminum ethoxide, diethylaluminum ethoxide, diisobutylaluminum ethoxide, dimethylaluminum phenoxide, diethylaluminum phenoxide, diisobutylaluminum phenoxide, methylaluminum dimethoxide, ethylaluminum dimethoxide, isobutylaluminum dimethoxide, methylaluminum diethoxide, ethylaluminum diethoxide, isobutylaluminum diethoxide, methylaluminum diphenoxide, ethylaluminum diphenoxide, and isobutylaluminum diphenoxide, but are not limited thereto.

[0040] Another class of organoaluminum compounds suitable for use as alkylating agents in lanthanide-based catalyst systems is aluminoxane. Aluminoxane can include oligomeric linear aluminoxane that can be represented by the following general formula, and

Chemical formula

Chemical formula

[0041] The preparation of aluminoxane can be carried out by reacting a trihydrocarbyl aluminum compound with water. This reaction can be carried out by known methods such as (1) a method of dissolving the trihydrocarbyl aluminum compound in an organic solvent and then contacting it with water, (2) a method of reacting the trihydrocarbyl aluminum compound with water adsorbed on, for example, the water of crystallization contained in a metal salt or an inorganic or organic compound, or (3) a method of reacting the trihydrocarbyl aluminum compound with water in the presence of a monomer or monomer solution to be polymerized.

[0042] Suitable aluminoxane compounds include, but are not limited to, methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, n-propylaluminoxane, isopropylaluminoxane, butylaluminoxane, isobutylaluminoxane, n-pentylaluminoxane, neopentylaluminoxane, n-hexylaluminoxane, n-octylaluminoxane, 2-ethylhexylaluminoxane, cyclohexylaluminoxane, 1-methylcyclopentylaluminoxane, phenylaluminoxane, and 2,6-dimethylphenylaluminoxane. The formation of modified methylaluminoxane can be achieved by substituting about 5 to 95% of the methyl groups of methylaluminoxane with C2-C 12 hydrocarbyl groups, preferably isobutyl groups.

[0043] In one or more embodiments, the aluminoxane can be used alone or in combination with other organoaluminum compounds. In one embodiment, methylaluminoxane can be used in combination with at least one other organoaluminum compound (AlR n X 3-n etc.), for example, diisobutylaluminum hydride. U.S. Patent Application Publication No. 2008 / 0182954 shows other examples of using aluminoxane and organoaluminum compounds in combination, and this document is hereby incorporated by reference in its entirety. In one or more embodiments, the catalyst composition used in the present invention lacks, or is substantially lacking in, aluminoxane. Organic magnesium compound

[0044] As described above, alkylating agents useful in the lanthanide-based catalyst system can include organomagnesium compounds. In one or more embodiments, the organomagnesium compounds that can be used include those represented by the general formula MgR2 (wherein each R is independently a monovalent organic group that may be bonded to the magnesium atom via a carbon atom). In one or more embodiments, each R is independently a hydrocarbyl group, for example, but not limited to, an alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an alkenyl group, a cycloalkenyl group, a substituted cycloalkenyl group, an aryl group, an allyl group, a substituted aryl group, an aralkyl group, an alkaryl group, and an alkynyl group, and each group contains from 1 carbon atom (or the minimum number of carbon atoms appropriate to form the group) up to about 20 carbon atoms. These hydrocarbyl groups may also contain heteroatoms, for example, but not limited to, nitrogen, oxygen, silicon, sulfur, and phosphorus atoms.

[0045] Suitable organomagnesium compounds that can be represented by the general formula MgR2 include, but are not limited to, diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium, dibutylmagnesium, dihexylmagnesium, diphenylmagnesium, and dibenzylmagnesium.

[0046] Another class of organomagnesium compounds that can be used as alkylating agents can be represented by the general formula RMgX, where R may be a monovalent organic group bonded to the magnesium atom through a carbon atom, and X may be a hydrogen atom, a halogen atom, a carboxylate group, an alkoxide group, or an aryloxide group. When the alkylating agent is an organomagnesium compound containing a halogen atom, the organomagnesium compound can function as both the alkylating agent and at least a part of the halogen source in the catalyst system. In one or more embodiments, R may be a hydrocarbyl group, such as, but not limited to, an alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an alkenyl group, a cycloalkenyl group, a substituted cycloalkenyl group, an aryl group, an allyl group, a substituted aryl group, an aralkyl group, an alkaryl group, and an alkynyl group, and each group contains from 1 carbon atom (or the minimum number of carbon atoms appropriate to form the group) up to about 20 carbon atoms. These hydrocarbyl groups may also contain heteroatoms, such as, but not limited to, nitrogen atoms, oxygen atoms, boron atoms, silicon atoms, sulfur atoms, and phosphorus atoms. In one embodiment, X may be a carboxylate group, an alkoxide group, or an aryloxide group, and each group contains from 1 to about 20 carbon atoms.

[0047] Examples of the types of organomagnesium compounds that can be represented by the general formula RMgX include, but are not limited to, hydrocarbylmagnesium hydride, hydrocarbylmagnesium halide, hydrocarbylmagnesium carboxylate, hydrocarbylmagnesium alkoxide, and hydrocarbylmagnesium aryloxide.

[0048] Suitable organomagnesium compounds that can be represented by the general formula RMgX include methylmagnesium hydride, ethylmagnesium hydride, butylmagnesium hydride, hexylmagnesium hydride, phenylmagnesium hydride, benzylmagnesium hydride, methylmagnesium chloride, ethylmagnesium chloride, butylmagnesium chloride, hexylmagnesium chloride, phenylmagnesium chloride, benzylmagnesium chloride, methylmagnesium bromide, ethylmagnesium bromide, butylmagnesium bromide, hexylmagnesium bromide, phenylmagnesium bromide, benzylmagnesium bromide, methylmagnesium hexanoate, ethylmagnesium hexanoate, butylmagnesium hexanoate, hexylmagnesium hexanoate, phenylmagnesium hexanoate, benzylmagnesium hexanoate, methylmagnesium ethoxide, ethylmagnesium ethoxide, butylmagnesium ethoxide, hexylmagnesium ethoxide, phenylmagnesium ethoxide, benzylmagnesium ethoxide, methylmagnesium phenoxide, ethylmagnesium phenoxide, butylmagnesium phenoxide, hexylmagnesium phenoxide, phenylmagnesium phenoxide, and benzylmagnesium phenoxide, but are not limited thereto. Halogen source

[0049] As described above, the lanthanide-based catalyst system used in the present invention can include a halogen source. As used herein, the term "halogen source" refers to any substance containing at least one halogen atom. In one or more embodiments, it is possible to provide at least a portion of the halogen source by either the aforementioned lanthanide-containing compound and / or the aforementioned alkylating agent when these compounds contain at least one halogen atom. In other words, the lanthanide-containing compound can function as both the lanthanide-containing compound and at least a portion of the halogen source. Similarly, the alkylating agent can function as both the alkylating agent and at least a portion of the halogen source.

[0050] In another embodiment, at least a portion of the halogen source can be present in the catalyst system in the form of discrete and different halogen-containing compounds. Various compounds (or mixtures thereof) containing one or more halogen atoms can be used as the halogen source. Examples of halogen atoms include, but are not limited to, fluorine, chlorine, bromine, and iodine. Combinations of two or more types of halogen atoms can also be used. Halogen-containing compounds that are soluble in hydrocarbon solvents are suitable for use in the present invention. However, halogen-containing compounds that are insoluble in hydrocarbons are also useful because they can be suspended in the polymerization system to form catalytically active species.

[0051] Useful types of halogen-containing compounds that can be used include, but are not limited to, elemental halogens, mixed halogens, hydrogen halides, organic halides, inorganic halides, metal halides, and organometallic halides.

[0052] Suitable elemental halogens include, but are not limited to, fluorine, chlorine, bromine, and iodine. Some specific examples of suitable mixed halogens include iodine monochloride, iodine monobromide, iodine trichloride, and iodine pentafluoride.

[0053] Suitable hydrogen halides include, but are not limited to, hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide.

[0054] Suitable organic halides include, but are not limited to, t-butyl chloride, t-butyl bromide, allyl chloride, allyl bromide, benzyl chloride, benzyl bromide, chloro-diphenylmethane, bromo-diphenylmethane, triphenylmethyl chloride, triphenylmethyl bromide, benzylidene chloride, benzylidene bromide, methyltrichlorosilane, phenyltrichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane, trimethylchlorosilane, benzoyl chloride, benzoyl bromide, propionyl chloride, propionyl bromide, methyl chloroformate, and methyl bromoformate.

[0055] Suitable inorganic halides include, but are not limited to, phosphorus trichloride, phosphorus tribromide, phosphorus pentachloride, phosphorus oxychloride, phosphorus oxybromide, boron trifluoride, boron trichloride, boron tribromide, silicon tetrafluoride, silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, arsenic trichloride, arsenic tribromide, arsenic triiodide, selenium tetrachloride, selenium tetrabromide, tellurium tetrachloride, tellurium tetrabromide, and tellurium tetraiodide.

[0056] Suitable metal halides include, but are not limited to, tin tetrachloride, tin tetrabromide, aluminum trichloride, aluminum tribromide, antimony trichloride, antimony pentachloride, antimony tribromide, aluminum triiodide, aluminum trifluoride, gallium trichloride, gallium tribromide, gallium triiodide, gallium trifluoride, indium trichloride, indium tribromide, indium triiodide, indium trifluoride, titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, zinc dichloride, zinc dibromide, zinc diiodide, and zinc difluoride.

[0057] Suitable organometallic halides include, but are not limited to, dimethylaluminum chloride, diethylaluminum chloride, dimethylaluminum bromide, diethylaluminum bromide, dimethylaluminum fluoride, diethylaluminum fluoride, methylaluminum dichloride, ethylaluminum dichloride, methylaluminum dibromide, ethylaluminum dibromide, methylaluminum difluoride, ethylaluminum difluoride, methylaluminum sesquichloride, ethylaluminum sesquichloride, isobutylaluminum sesquichloride, methylmagnesium chloride, methylmagnesium bromide, methylmagnesium iodide, ethylmagnesium chloride, ethylmagnesium bromide, butylmagnesium chloride, butylmagnesium bromide, phenylmagnesium chloride, phenylmagnesium bromide, benzylmagnesium chloride, trimethyltin chloride, trimethyltin bromide, triethyltin chloride, triethyltin bromide, di-t-butyltin dichloride, di-t-butyltin dibromide, dibutyltin dichloride, dibutyltin dibromide, tributyltin chloride, and tributyltin bromide. Non-coordinating anion / non-coordinating anion precursor

[0058] In one or more embodiments, the lanthanide-based catalyst system can include a compound containing a non-coordinating anion or a non-coordinating anion precursor. In one or more embodiments, a compound containing a non-coordinating anion or a non-coordinating anion precursor can be used in place of the halogen source described above. A non-coordinating anion is a sterically bulky anion that, due to steric hindrance, does not form a coordination bond with, for example, the active center of the catalyst system. Non-coordinating anions useful in the present invention include, but are not limited to, tetraarylborate anions and fluorinated tetraarylborate anions. Further, a compound containing a non-coordinating anion can contain a counter cation, such as a carbonium, ammonium, or phosphonium cation. Exemplary counter cations include, but are not limited to, triarylcarbonium cations and N,N-dialkylanilinium cations. Examples of compounds containing non-coordinating anions and counter cations include, but are not limited to, triphenylcarbonium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, triphenylcarbonium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, and N,N-dimethylanilinium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

[0059] In this embodiment, a non-coordinating anion precursor can also be used. A non-coordinating anion precursor is a compound that can form a non-coordinating anion under reaction conditions. Useful non-coordinating anion precursors include, but are not limited to, triarylboron compounds, BR3 (wherein R is an aryl group with a high electron-withdrawing property, such as a pentafluorophenyl or 3,5-bis(trifluoromethyl)phenyl group).

[0060] The formation of the lanthanide-based catalyst composition used in the present invention may be carried out by combining or mixing the aforementioned catalyst components. One or more active catalyst species are considered to be obtained from combinations of lanthanide-based catalyst components, but the exact degree of interaction or reaction between the various catalyst components or components is not well understood. Accordingly, the term "catalyst composition" is used to encompass simple mixtures of components, composites of various components resulting from physical or chemical attraction, chemical reaction products of components, or combinations thereof as described above. amount

[0061] The aforementioned lanthanide-based catalyst composition may have high catalytic activity for polymerizing conjugated dienes to cis-1,4-polybutadiene over a wide range of catalyst concentrations and catalyst component ratios. Several factors may affect the optimal concentration of any one of the catalyst components. For example, since the catalyst components may interact to form active species, the optimal concentration for any one catalyst component may depend on the concentration of other catalyst components.

[0062] In one or more embodiments, the molar ratio of the alkylating agent to the lanthanide-containing compound (alkylating agent / Ln) may vary from about 1:1 to about 1,000:1, in other embodiments from about 2:1 to about 500:1, and in other embodiments from about 5:1 to about 200:1.

[0063] In these embodiments where aluminoxane and at least one other organoaluminum agent are used as the alkylating agent, the molar ratio of aluminoxane to the lanthanide-containing compound (aluminoxane / Ln) may vary from 5:1 to about 1,000:1, in other embodiments from about 10:1 to about 700:1, and in other embodiments from about 20:1 to about 500:1, and the molar ratio of at least one other organoaluminum compound to the lanthanide-containing compound (Al / Ln) may vary from about 1:1 to about 200:1, in other embodiments from about 2:1 to about 150:1, and in other embodiments from about 5:1 to about 100:1.

[0064] The molar ratio of the halogen-containing compound to the lanthanide-containing compound is best explained in terms of the ratio of the number of moles of halogen atoms in the halogen source to the number of moles of lanthanide atoms in the lanthanide-containing compound (halogen / Ln). In one or more embodiments, the halogen / Ln molar ratio can vary from about 0.5:1 to about 20:1, in other embodiments from about 1:1 to about 10:1, and in other embodiments from about 2:1 to about 6:1.

[0065] In yet another embodiment, the molar ratio of the non-coordinating anion or non-coordinating anion precursor to the lanthanide-containing compound (An / Ln) can be from about 0.5:1 to about 20:1, in other embodiments from about 0.75:1 to about 10:1, and in other embodiments from about 1:1 to about 6:1. Preparation of the catalyst system

[0066] The catalyst system used in the present invention can be formed by various methods.

[0067] In one or more embodiments, the in-situ formation of the lanthanide-based catalyst composition can be carried out by adding the catalyst components stepwise or simultaneously to a solution (or bulk monomer) containing the monomer and the solvent. In one embodiment, the alkylating agent can be added first, followed by the lanthanide-containing compound, and then a compound containing the halogen source or the non-coordinating anion or non-coordinating anion precursor.

[0068] In one or more embodiments, the lanthanide-based catalyst composition can be preformed. That is, the catalyst components are preliminarily mixed outside the polymerization system. In one or more embodiments, an active catalyst system is formed by preliminarily mixing the catalyst components. This active catalyst system can polymerize monomers, particularly conjugated diene monomers, into the desired cis-1,4-polybutadiene desired in one or more embodiments of the present invention. Examples of useful processes for preforming lanthanide-based catalyst compositions are disclosed in U.S. Patent Nos. 5,686,371, 6,576,731, U.S. Patent Application Publication Nos. 2002 / 0,035,226, 2012 / 0,208,964, 2013 / 0,237,669. These documents are incorporated herein by reference. Order of addition

[0069] In one or more embodiments, the catalyst system may be formed by mixing the catalyst components simultaneously or sequentially. When the components are mixed sequentially, first, the alkylating agent can be mixed with the lanthanide-containing compound, and then the mixture can be mixed with a compound containing a halogen source or a non-coordinating anion or a non-coordinating anion precursor. In other embodiments, first, the alkylating agent and the halogen source (or non-coordinating anion or non-coordinating anion precursor) can be mixed, and then the mixture can be mixed with the lanthanide-containing compound. In still other embodiments, first, the lanthanide-containing compound and the halogen source (or non-coordinating anion or non-coordinating anion precursor) can be mixed, and then the mixture can be mixed with the alkylating agent. Use of solvent

[0070] In one or more embodiments, a solvent can be used as a carrier to dissolve or suspend the catalyst to facilitate delivery of the catalyst to the polymerization system. In other embodiments, the monomer can be used as a carrier. In still other embodiments, the catalyst or initiator can be used in their undiluted state without using any solvent.

[0071] In one or more embodiments, the catalyst is preformed. In one or more embodiments, the preformation of the catalyst can be carried out with a solvent. In one or more embodiments, the solvent can be used as a carrier to dissolve or suspend the catalyst to facilitate the delivery of the catalyst to the polymerization system. In other embodiments, the monomer can be used as a carrier. In still other embodiments, the catalyst can be used undiluted without using any solvent.

[0072] In one or more embodiments, suitable solvents include organic compounds that do not polymerize and are not incorporated into the propagating polymer chains during the polymerization of the monomer in the presence of the catalyst or initiator. In one or more embodiments, these organic species are liquid at ambient temperature and pressure. In one or more embodiments, these organic solvents are inert to the catalyst or initiator. Exemplary organic solvents include hydrocarbons having low or relatively low boiling points such as aromatic hydrocarbons, aliphatic hydrocarbons, and cycloaliphatic hydrocarbons. Non-limiting examples of aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, diethylbenzene, and mesitylene. Non-limiting examples of aliphatic hydrocarbons include n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, isopentane, isohexane, isopentane, isooctane, 2,2-dimethylbutane, petroleum ether, kerosene, and petroleum spirit. Also, examples of cycloaliphatic hydrocarbons include cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane, but are not limited thereto. Mixtures of the above hydrocarbons can also be used. As is known in the art, for environmental reasons, it may be desirable to use aliphatic hydrocarbons and cycloaliphatic hydrocarbons. The low-boiling hydrocarbon solvent is typically separated from the polymer after the polymerization is complete.

[0073] Other examples of organic solvents include high molecular weight, high boiling point hydrocarbons, including hydrocarbon oils commonly used in oil-extended polymers. Examples of these oils include paraffinic oils, aromatic oils, naphthenic oils, vegetable oils other than castor oil, and low PCA oils such as MES, TDAE, SRAE, and heavy naphthenic oils. Since these hydrocarbons are non-volatile, they typically do not need to be separated and remain incorporated within the polymer. Use of Stabilizers

[0074] In one or more embodiments, the preparation of the catalyst system may optionally be carried out in the presence of a small amount of an alkene-containing compound that can stabilize the catalyst system. Useful alkene-containing compounds can include monomers as defined herein. Specific examples of monomers suitable for stabilizing the catalyst system include conjugated diene monomers such as 1,3-butadiene or isoprene. The amount of alkene-containing compound that can be used to stabilize the catalyst can range from about 1 to about 500 moles, in other embodiments from about 2 to about 250 moles, in other embodiments from about 3 to about 100 moles, in other embodiments from about 5 to about 500 moles, in other embodiments from about 10 to about 20 moles per mole of the lanthanide-containing compound. Conditions for Catalyst System Formation

[0075] In one or more embodiments, the catalyst system used in the present invention may be prepared at a specific temperature. In one or more embodiments, the preparation of the catalyst composition can be carried out at a temperature of -20°C or higher, in other embodiments 0°C or higher, in other embodiments 20°C or higher, in other embodiments 40°C or higher. In these or other embodiments, the preparation of the catalyst composition can be carried out at a temperature of 100°C or lower, in other embodiments 80°C or lower, in other embodiments 60°C or lower, in other embodiments 40°C or lower, in other embodiments 20°C or lower, in other embodiments 0°C or lower. Aging of the Catalyst System

[0076] In one or more embodiments, the catalyst composition may be aged before use (i.e., before addition to the polymerization system).

[0077] In one or more embodiments, the aging of the catalyst composition may be carried out at a temperature of -20 °C or higher, in other embodiments 0 °C or higher, in other embodiments 20 °C or higher, in other embodiments 40 °C or higher. In these or other embodiments, the aging of the catalyst composition may be carried out at a temperature of 100 °C or lower, in other embodiments 80 °C or lower, in other embodiments 60 °C or lower, in other embodiments 40 °C or lower, in other embodiments 20 °C or lower, in other embodiments 0 °C or lower. In certain embodiments, the catalyst composition may be aged in an environment where temperature control is not performed, where the catalyst composition may be exposed to a changing ambient temperature. In these or other embodiments, the catalyst composition may be aged at the above-described temperatures. Also, for at least a portion of the aging time, it may be further aged at an uncontrolled temperature.

[0078] In one or more embodiments, the aging of the catalyst composition may be carried out for 10 minutes or longer, in other embodiments 30 minutes or longer, in other embodiments 1 hour or longer, in other embodiments 3 hours or longer, in other embodiments 6 hours or longer, in other embodiments 12 hours or longer, in other embodiments 24 hours or longer, in other embodiments 6 days or longer, in other embodiments 12 days or longer, in other embodiments 30 days or longer, in other embodiments 60 days or longer. In these or other embodiments, the aging of the catalyst composition may be carried out for 1000 days or shorter, in other embodiments 750 days or shorter, in other embodiments 500 days or shorter, in other embodiments 300 days or shorter, in other embodiments 100 days or shorter, in other embodiments 24 days or shorter, in other embodiments 18 days or shorter, in other embodiments 12 days or shorter. In one or more embodiments, the aging of the catalyst composition is carried out for about 4 to about 16 days, in other embodiments about 5 to about 15 days, in other embodiments about 6 to about 12 days. Specific catalyst systems

[0079] In one or more embodiments, the catalyst used in the practice of the present invention is a preformed catalyst that is a combination or reaction product of a lanthanide carboxylate, an aluminum hydride, and an organometallic halide. In a specific embodiment, the lanthanide carboxylate is neodymium carboxylate, the aluminum hydride is dihydrocarbylaluminum hydride and / or hydrocarbylaluminum dihydride, and the organometallic halide is hydrocarbylaluminum sesquichloride. In a more specific embodiment, the catalyst system is a combination or reaction product of neodymium neodecanoate, diisobutylaluminum hydride, and ethylaluminum sesquichloride. The molar ratio of diisobutylaluminum hydride to neodymium neodecanoate in the catalyst system can be from about 5 to about 40, and in other embodiments can be from about 10 to about 20. Also, the molar ratio of ethylaluminum sesquichloride to neodymium neodecanoate in the catalyst system (best described as the molar ratio of the halogen atoms in ethylaluminum sesquichloride to the lanthanide atoms in neodymium neodecanoate (halogen / Ln)) can be from about 1 to about 4, and in other embodiments can be from about 2 to about 3. In these or other embodiments, these specific catalyst systems can include a conjugated diene (e.g., 1,3-butadiene or isoprene) as a stabilizer. In a more specific embodiment, the specific catalyst systems described are aged as described herein.

[0080] The catalyst system that can be used in one or more embodiments of the present invention may be a commercially available one. For example, as useful preformed catalyst systems, those with the trade names COMCAT Nd-FC(NH), COMCAT Nd-FC / 20(NH), COMCAT Nd-FC / SF [COMAR CHEMICALS (Pty) Ltd] can be used. Polymerization mixture

[0081] The production of the reactive polymer according to the present invention can be carried out by polymerizing a catalytically effective amount of a catalyst with a sufficient amount of a conjugated diene monomer to produce a polymer of a desired molecular weight. By introducing the catalyst and the conjugated diene monomer, a polymerization mixture is formed. This polymerization mixture is sometimes also referred to as a polymerization system, where the reactive polymer is formed. The amount of catalyst to be used may depend on the interaction of various factors (e.g., the type of catalyst or initiator used, the purity of the components, the polymerization temperature, the desired polymerization rate and conversion, the desired molecular weight, and many other factors). Therefore, regarding the specific amount of catalyst or initiator, it cannot be clearly stated other than that a catalytically effective amount of catalyst or initiator may be used.

[0082] In one or more embodiments, the amount of the coordination metal compound (e.g., lanthanide-containing compound) used can be varied from about 0.001 to about 2 mmol, in other embodiments from about 0.005 to about 1 mmol, and in still other embodiments from about 0.01 to about 0.2 mmol (per 100 grams of monomer).

[0083] In one or more embodiments, the polymerization may be carried out in a polymerization system containing a significant amount of solvent. In one embodiment, a solution polymerization system in which both the monomer to be polymerized and the formed polymer are soluble in the solvent may be used. In another embodiment, a precipitation polymerization system may be used by selecting a solvent in which the formed polymer is insoluble. In either case, in addition to the amount of solvent that may be used when preparing the catalyst or initiator, an amount of solvent is usually added to the polymerization system. The additional solvent may be the same as or different from the solvent used when preparing the catalyst or initiator. Exemplary solvents have been described above. In one or more embodiments, the solvent content of the polymerization mixture can be more than 20% by weight, in other embodiments more than 50% by weight, and in still other embodiments more than 80% by weight based on the total weight of the polymerization mixture.

[0084] In other embodiments, the polymerization system used can generally be considered a bulk polymerization system that is substantially solvent-free or contains a minimal amount of solvent. One of ordinary skill in the art will understand the benefits of a bulk polymerization process (i.e., a process in which the monomer serves as the solvent). Thus, it will be understood that the amount of solvent contained in the polymerization system is less than an amount that would have an adverse effect on the benefits sought by performing bulk polymerization. In one or more embodiments, the solvent content of the polymerization mixture can be less than about 20% by weight, in other embodiments less than about 10% by weight, and in still other embodiments less than about 5% by weight, based on the total weight of the polymerization mixture. In another embodiment, the polymerization mixture contains no solvent other than the solvent inherent to the raw materials used. In yet another embodiment, the polymerization mixture is substantially devoid of solvent. This refers to the absence of an amount of solvent that would have a significant impact on the polymerization process if present. A polymerization system that is substantially devoid of solvent can also be said to be substantially solvent-free. In certain embodiments, the polymerization mixture is devoid of solvent.

[0085] The polymerization may be carried out in any conventional polymerization vessel known in the art. In one or more embodiments, solution polymerization can be carried out in a conventional stirred tank reactor. In other embodiments, bulk polymerization can be carried out in a conventional stirred tank reactor, particularly when the monomer conversion is less than about 60%. In still other embodiments, particularly when the monomer conversion in the bulk polymerization process exceeds about 60% (in which case, typically, a highly viscous cement is obtained), bulk polymerization may be carried out in an elongated reactor (where the viscous cement during polymerization is moved by or substantially by a piston). For example, an extruder in which the cement is extruded by a self-cleaning single-screw or twin-screw agitator is suitable for this purpose. An example of a useful bulk polymerization process is disclosed in U.S. Patent No. 7,351,776, which is incorporated herein by reference.

[0086] In one or more embodiments, all of the components used for the polymerization can be mixed in a single vessel (e.g., a conventional stirred tank reactor), and all steps of the polymerization process can be carried out in this vessel. In other embodiments, two or more components can be pre-combined in one vessel and then transferred to another vessel where polymerization of the monomer (or at least a majority thereof) can be carried out.

[0087] The polymerization can be carried out as a batch process, a continuous process, or a semi-continuous process. In a semi-continuous process, the monomer is intermittently charged as needed to replace the already polymerized monomer. In one or more embodiments, the conditions under which the polymerization proceeds can be controlled to maintain the temperature of the polymerization mixture in the range of about -10°C to about 200°C, in other embodiments about 0°C to about 150°C, and in other embodiments about 20°C to about 100°C. In one or more embodiments, the heat of polymerization can be removed by external cooling with a thermally controlled reactor jacket, internal cooling by vaporization and condensation of the monomer using a reflux condenser connected to the reactor, or a combination of the two methods. Also, the polymerization conditions can be controlled to set the pressure at which the polymerization is carried out to be about 0.01 MPa to about 5 MPa (about 0.1 atm to about 50 atm), in other embodiments about 0.05 MPa to about 2 MPa (about 0.5 atm to about 20 atm), and in other embodiments about 0.1 MPa to about 1 MPa (about 1 atm to about 10 atm). In one or more embodiments, the pressure at which polymerization can occur includes the pressure at which most of the monomer is surely in the liquid phase. In these or other embodiments, the polymerization mixture can be maintained under anaerobic conditions. Pseudo-living polymer

[0088] The polymers produced by polymerization with a lanthanide catalyst can be polymers in which some or all of the resulting polymer chains possess reactive chain ends before the polymerization mixture is quenched. Therefore, when referring to a reactive polymer, it is referring to a polymer having reactive chain ends. As described above, the reactive polymers prepared using a lanthanide catalyst are sometimes referred to as pseudo-living polymers. In one or more embodiments, a polymerization mixture containing a reactive polymer may also be referred to as an active polymerization mixture or an active polymerization system. The percentage of polymer chains having reactive ends depends on various factors (e.g., the type of catalyst or initiator, the type of monomer, the purity of the components, the polymerization temperature, the monomer conversion rate, and many other factors). In one or more embodiments, at least about 20% of the polymer chains possess reactive ends, in other embodiments, at least about 50% of the polymer chains possess reactive ends, and in still other embodiments, at least about 80% of the polymer chains possess reactive ends. In any case, in accordance with aspects of the present invention, the reactive polymer can be treated with a Lewis acid. Functionalization reaction

[0089] In one or more embodiments, a reactive polymer containing reactive chain ends can optionally be end-functionalized by reacting its reactive chain ends with a functionalizing agent. In one or more embodiments, this functionalization is carried out before treatment with a Lewis acid. In one or more embodiments, the polydienes of the present invention are not functionalized.

[0090] In one or more embodiments, the reaction between any functionalizing agent and the reactive polymer can be carried out after a desired monomer conversion has been achieved and before the polymerization mixture is quenched by a quenching agent. In one or more embodiments, the reaction between the functionalizing agent and the reactive polymer occurs within 2 hours after reaching the peak polymerization temperature, within 1 hour in other embodiments, within 30 minutes in other embodiments, within 5 minutes in other embodiments, and within 1 minute in other embodiments. In one or more embodiments, the reaction between the functionalizing agent and the reactive polymer can occur immediately after reaching the peak polymerization temperature. In other embodiments, the reaction between the functionalizing agent and the reactive polymer can occur after the reactive polymer has been stored. In one or more embodiments, the storage of the reactive polymer is carried out at or below room temperature under an inert atmosphere. In one or more embodiments, the temperature at which the reaction between the functionalizing agent and the reactive polymer occurs can be from about 10°C to about 150°C, or from about 20°C to about 100°C in other embodiments. The time required for the reaction between the functionalizing agent and the reactive polymer to end depends on various factors (e.g., the type and amount of catalyst used to prepare the reactive polymer, the type and amount of functionalizing agent, and the temperature at which the functionalization reaction is carried out). In one or more embodiments, the reaction between the functionalizing agent and the reactive polymer can be carried out for about 10 to 60 minutes.

[0091] In one or more embodiments, any functionalizing agent may be introduced into the polymerization mixture at the location where the polymerization is carried out (e.g., within a vessel). In other embodiments, any functionalizing agent may be introduced into the polymerization mixture at a location different from the location where the polymerization is carried out. For example, any functionalizing agent may be introduced into the polymerization mixture within a downstream vessel (including a downstream reactor or tank, an in-line reactor or mixer, an extruder, or a devolatilization device). Functionalizing agent

[0092] In one or more embodiments, suitable functionalizing agents include compounds containing groups capable of reacting with the reactive polymers produced according to the present invention. Exemplary functionalizing agents include ketones, quinones, aldehydes, amides, esters, isocyanates, isothiocyanates, epoxides, imines, aminoketones, aminothioketones, and acid anhydrides. Examples of these compounds are disclosed in U.S. Pat. Nos. 4,906,706, 4,990,573, 5,064,910, 5,567,784, 5,844,050, 6,838,526, 6,977,281, and 6,992,147, U.S. Patent Application Publication Nos. 2006 / 0004131(A1), 2006 / 0025539(A1), 2006 / 0030677(A1), and 2004 / 0147694(A1), and Japanese Patent Application Nos. 05-051406(A), 05-059103A, 10-306113(A), and 11-035633(A). These documents are hereby incorporated by reference into this specification. Other examples of functionalizing agents include azine compounds as described in U.S. Pat. No. 7,879,952, hydrobenzamide compounds as disclosed in U.S. Pat. No. 7,671,138, nitro compounds as disclosed in U.S. Pat. No. 7,732,534, protected oxime compounds as disclosed in U.S. Pat. No. 8,088,868, heterocyclic nitrile compounds as disclosed in U.S. Pat. No. 8,314,189, halosilanes containing an amino group as disclosed in U.S. Pat. No. 8,258,332, imide compounds containing a protected amino group as disclosed in U.S. Pat. No. 7,906,592, nitroso compounds as disclosed in U.S. Patent Application Publication No. 2010 / 0168378, amino-containing compounds as disclosed in U.S. Patent Application Publication No. 2010 / 0099826, carboxylic acid esters or thiocarboxylic acid esters containing a silylated amino group as disclosed in U.S. Patent Application Publication No. 2011 / 0077325, polyoxime compounds as disclosed in U.S. Patent Application Publication No. 2011 / 0152449, polycyano compounds as disclosed in U.S. Patent Application Publication No. 2011 / 0288200, and nitrile compounds containing a protected amino group as disclosed in U.S. Patent Application Publication No. 2012 / 0059112.All of these disclosures are incorporated herein by reference.

[0093] The amount of any functionalizing agent that can be added to the polymerization mixture to obtain a functionalized polymer may depend on various factors (including the type and amount of catalyst used to synthesize the reactive polymer and the desired degree of functionalization). In one or more embodiments, when preparing a reactive polymer using a lanthanide-based catalyst, the amount of functionalizing agent used can be described based on the lanthanide metal of the lanthanide-containing compound. For example, the molar ratio of the functionalizing agent to the lanthanide metal can be from about 1:1 to about 200:1, in other embodiments from about 5:1 to about 150:1, and in other embodiments from about 10:1 to about 100:1. Lewis acid treatment

[0094] According to an aspect of the present invention, the reactive polymer is treated with a Lewis acid. In one or more embodiments, the Lewis acid is introduced into the polymerization system containing the reactive polymer (i.e., into the active polymerization mixture). In one or more embodiments, the introduction of the Lewis acid into the active polymerization mixture is carried out after the desired monomer conversion is achieved and before the polymerization mixture is quenched with a quenching agent. In one or more embodiments, the introduction of the Lewis acid into the active polymerization mixture can be carried out within 2 hours after reaching the peak polymerization temperature, in other embodiments within 1 hour, in other embodiments within 30 minutes, in other embodiments within 5 minutes, and in other embodiments within 1 minute. In one or more embodiments, the introduction of the Lewis acid into the active polymerization mixture can be carried out immediately after reaching the peak polymerization temperature. In other embodiments, the introduction of the Lewis acid into the active polymerization mixture can be carried out after the reactive polymer has been stored. In one or more embodiments, the storage of the reactive polymer is carried out at or below room temperature under an inert atmosphere. In one or more embodiments, since the introduction of the Lewis acid into the reactive polymer is carried out before quenching and / or functionalization, the polymer is in a reactive (i.e., pseudo-living) state at the time of introduction of the Lewis acid.

[0095] As described above, the polymer may optionally be functionalized. In one or more embodiments, the introduction of the Lewis acid may be performed simultaneously with the introduction of any functionalizing agent. In other embodiments, the introduction of the Lewis acid into the polymerization mixture may be performed after any functionalizing agent has been introduced and before the polymerization mixture is quenched with a quenching agent. In one or more embodiments, the introduction of the Lewis acid into the living polymerization mixture may be performed within 2 hours after any functionalizing agent has been introduced, within 1 hour in other embodiments, within 30 minutes in other embodiments, within 5 minutes in other embodiments, and within 1 minute in other embodiments.

[0096] In one or more embodiments, the temperature at which the Lewis acid is introduced into the living polymerization mixture may be from about 10 °C to about 150 °C, or from about 20 °C to about 100 °C in other embodiments. The time required for the reaction or interaction between the Lewis acid and any component of the polymerization mixture may depend on various factors (e.g., the type and amount of catalyst used in the preparation of the reactive polymer, the type and amount of Lewis acid, and the temperature at which the Lewis acid is introduced). In one or more embodiments, the Lewis acid and the reactive polymer are aged for at least 1 minute, at least 5 minutes in other embodiments, at least 20 minutes in other embodiments, at least 1 hour in other embodiments, and at least 2 hours in other embodiments before any quenching of the polymerization system.

[0097] In one or more embodiments, the Lewis acid may be introduced into the polymerization mixture at the location where the polymerization is carried out (e.g., in a vessel). In other embodiments, the Lewis acid may be introduced into the polymerization mixture at a location different from the location where the polymerization is carried out. For example, it may be introduced into the polymerization mixture in a downstream vessel (including a downstream reactor or tank, an in-line reactor or mixer, an extruder, or a devolatilization device).

[0098] In one or more embodiments, the amount of Lewis acid introduced into the polymerization system may be defined relative to the amount of lanthanide metal (e.g., neodymium atoms) in the polymerization system used for the preparation of the polymer. In one or more embodiments, the molar ratio of Lewis acid to lanthanide metal in the lanthanide-containing compound (LA / Ln) is at least 0.5:1, in other embodiments at least 1:1, and in other embodiments at least 5:1. In these or other embodiments, the molar ratio of Lewis acid to lanthanide metal (LA / Ln) is at most 150:1, in other embodiments at most 100:1, and in other embodiments at most 50:1. In one or more embodiments, the LA / Ln molar ratio is from about 0.5:1 to about 150:1, in other embodiments from about 1:1 to about 100:1, and in other embodiments from about 5:1 to about 50:1. Lewis acid

[0099] One of ordinary skill in the art will understand that a Lewis acid includes a compound that reacts with a Lewis base to form a Lewis adduct. According to this mechanism, the Lewis base donates an electron pair to the Lewis acid, and the Lewis acid accepts the electron pair. In one or more embodiments, the Lewis acid is not a Bronsted-Lowry acid and does not have an acidic hydrogen atom.

[0100] In one or more embodiments, the Lewis acid may be selected from titanium tetraalkoxides, boron trihalides, trihydrocarbylboranes, trihydrocarbyloxyborates, trihydrocarbylsilyl halides, trihydrocarbylsilyl triflates, silicon tetrahalides, titanium tetrahalides, aluminum trihalides, zinc dihalides, and phosphorus trihalides.

[0101] In one or more embodiments, the Lewis acid may be selected from boron trihalides, trihydrocarbylboranes, trihydrocarbyloxyborates, trihydrocarbylsilyl halides, silicon tetrahalides, titanium tetrahalides, and phosphorus trihalides.

[0102] In one or more embodiments, the Lewis acid may be selected from boron trihalides, trihydrocarbyloxyborates, titanium tetrahalides, and phosphorus trihalides.

[0103] In one or more embodiments, the boron trihalide may be defined by the following formula:

Chemical formula

[0104] In one or more embodiments, the trihydrocarbyloxyborate may be defined by the following formula:

Chemical formula

[0105] In one or more embodiments, the monovalent organic group may be a hydrocarbyl group, including, but not limited to, alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, aryl group, allyl group, aralkyl group, alkaryl group, or alkynyl group. The hydrocarbyl group also includes substituted hydrocarbyl groups, which refer to hydrocarbyl groups in which one or more hydrogen atoms are replaced by substituents such as hydrocarbyl, hydrocarbyloxy, silyl, or silyloxy groups. In one or two or more embodiments, these groups may contain from 1 (or the minimum number of carbon atoms appropriate to form the group) to about 20 carbon atoms. These groups may also contain heteroatoms, such as, but not limited to, nitrogen atom, boron atom, oxygen atom, silicon atom, sulfur atom, tin atom, and phosphorus atom.

[0106] In one or more embodiments, the titanium tetrahalide can be defined by the following formula:

Chemical formula

[0107] In one or more embodiments, the phosphorus trihalide can be defined by the following formula:

Chemical formula

[0108] In one or more embodiments, the Lewis acid may be part of a Lewis acid-Lewis base complex. For example, the Lewis acid boron trihalide can be used as a boron trifluoride complex. Suitable Lewis bases for complex formation include, but are not limited to, alcohols, water, oxygen-containing mineral acids, water, aldehydes, amines, esters, thioesters, ethers, thioethers, ketones, and nitriles.

[0109] In one or more embodiments, the ketone can be defined by the formula RCOR, where each R is independently a monovalent organic group. Representative examples of ketones suitably used in the boron trifluoride complex include acetone, methyl ethyl ketone, dibutyl ketone, methyl isobutyl ketone, ethyl octyl ketone, 2,4-pentanedione, butyl cycloheptanone, acetophenone, amyl phenyl ketone, butyl phenyl ketone, benzophenone, phenyl tolyl ketone, and quinone. Representative examples of boron trifluoride ketone complexes include boron trifluoride acetophenone and boron trifluoride benzophenone.

[0110] In one or more embodiments, the aldehyde can be defined by the formula RCHO, where each R is independently a monovalent organic group. Representative examples of aldehydes suitably used in the boron trifluoride complex include butyl aldehyde, anisaldehyde, cinnamaldehyde, isobutyl aldehyde, heptaldehyde, dodecyl aldehyde, benzaldehyde, phenylacetaldehyde, o-tolualdehyde, m-tolualdehyde, p-tolualdehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, and m-hydroxybenzaldehyde. Representative examples of boron trifluoride aldehyde complexes include boron trifluoride benzaldehyde and boron trifluoride tolualdehyde.

[0111] In one or more embodiments, the ester may be defined by the formula R-COOR, where each R is independently a monovalent organic group. Representative examples of esters include ethyl butyrate, ethyl octanoate, isopropyl hexanoate, amyl acetate, hexyl propionate, cetyl acetate, ethyl benzoate, amyl benzoate, phenyl acetate, phenyl butyrate, and phenyl benzoate. Representative examples of boron trifluoride ester complexes include boron trifluoride ethyl benzoate, boron trifluoride ethyl acetate, and boron trifluoride phenyl acetate. Those skilled in the art will be able to readily prepare thioester analogs based on the above description of esters.

[0112] In one or more embodiments, the ether may be defined by the formula R-O-R, where each R is independently a monovalent organic group. Representative examples of ethers include ethoxybutane, butoxybutane, ethoxyoctane, isopropoxyhexane, propoxyhexane, ethoxybenzene, and amyloxybenzene. Representative examples of boron trifluoride ether complexes include boron trifluoride methyl t-butyl ether, boron trifluoride dibutyl ether, and boron trifluoride dimethyl ether. Those skilled in the art will be able to readily prepare thioether analogs based on the above description of ethers.

[0113] In one or more embodiments, the nitrile may be represented by the formula RCN, where each R is a monovalent organic group. Representative examples of nitriles include acetonitrile, butyronitrile, acrylonitrile, benzonitrile, o-tolunitrile, m-tolunitrile, p-tolunitrile, and phenylacetonitrile. A representative example of a boron trifluoride nitrile complex includes boron trifluoride benzonitrile. Quenching

[0114] In one or more embodiments, after the reaction between the reactive polymer and the Lewis acid has occurred or ended, a quenching agent can be added to the polymerization mixture to add protons to the reaction product between the reactive polymer and the Lewis acid, deactivate any remaining reactive polymer chains, and / or deactivate the catalyst or catalyst component. The quenching agent may include a protic compound, examples of which include, but are not limited to, alcohols, carboxylic acids, inorganic acids, water, or mixtures thereof. In certain embodiments, quenching with an alcohol such as isopropanol is used. This is because it has been found that the use of isopropyl alcohol contributes to certain desirable properties in the final polymer (e.g., desirable cold flow). An antioxidant such as 2,6-di-tert-butyl-4-methylphenol may be added before, during, or after the addition of the quenching agent. The amount of antioxidant used may range from 0.2 wt% to 1 wt% based on the weight of the polymer product. Additionally, the polymer product can be oil-extended by adding oil to the polymer, which may be in the form of a polymer cement or polymer dissolved or suspended in the monomer. In the practice of the present invention, the amount of oil that may be added is not limited, and thus a normal amount may be added (e.g., 5 - 50 phr). Useful oils or extenders that may be used include, but are not limited to, aromatic oils, paraffinic oils, naphthenic oils, vegetable oils other than castor oil, low PCA oils such as MES, TDAE, and SRAE, and heavy naphthenic oils. Recovery of Polymer

[0115] After quenching the polymerization mixture, the various components of the polymerization mixture may be recovered. In one or more embodiments, unreacted monomer can be recovered from the polymerization mixture. For example, the monomer can be distilled from the polymerization mixture using techniques known in the art. In one or more embodiments, a devolatilization apparatus can be used to remove the monomer from the polymerization mixture. After removing the monomer from the polymerization mixture, the monomer may be purified, stored, and / or recycled back to the polymerization process.

[0116] The polymer product may be recovered from the polymerization mixture using techniques known in the art. In one or more embodiments, solvent removal and drying techniques may be used. For example, the polymer can be recovered by passing the polymerization mixture through a heated screw device (e.g., a devolatilizing extruder). In this device, the removal of volatile substances is carried out by vaporization at an appropriate temperature (e.g., about 100 °C to about 170 °C) and at atmospheric pressure or near atmospheric pressure. By this treatment, unreacted monomers and any low-boiling solvents are removed. Alternatively, the polymer can be recovered by subjecting the polymerization mixture to steam devolatilization and subsequently drying the resulting polymer cake in a hot air tunnel. The polymer can also be recovered by directly drying the polymerization mixture on a drum dryer. Properties of the Polymer

[0117] In one or more embodiments, the polymer of the present invention is cis-1,4-polybutadiene having a cis-1,4-bond content of more than 60%, in other embodiments more than about 75%, in other embodiments more than about 90%, in other embodiments more than about 95%, in other embodiments more than about 96%, in other embodiments more than about 97%, in other embodiments more than about 98%, in other embodiments more than about 99%. These percentages are based on the number of diene mer units and employ the cis-1,4 bond to the total number of diene mer units. Also, these polymers can have a 1,2-bond content of less than 7%, in other embodiments less than 5%, in other embodiments less than 2%, in other embodiments less than 1%. These percentages are based on the number of diene mer units and employ the 1,2-bond to the total number of diene mer units. The remainder of the diene mer units may employ trans-1,4-bonds. The measurement of the cis-1,4-, 1,2-, and trans-1,4-bond contents may be carried out by infrared spectroscopy.

[0118] In one or other embodiments, the number average molecular weight (M n) can be from about 1,000 to about 1,000,000, in other embodiments from about 5,000 to about 200,000, in other embodiments from about 25,000 to about 150,000, and in other embodiments from about 50,000 to about 120,000. This value is measured using gel permeation chromatography (GPC) calibrated with polybutadiene standards and Mark-Houwink constants for the polymer. The molecular weight distribution or polydispersity (M w / M n ) of the cis-1,4-polybutadiene of the present invention can be from about 1.5 to about 5.0, and in other embodiments from about 2.0 to about 4.0. In these or other embodiments, the M w / M n of the cis-1,4-polybutadiene of the present invention can be less than 3.0, in other embodiments less than 2.5, in other embodiments less than 2.3, in other embodiments less than 2.2, in other embodiments less than 2.1, and in other embodiments less than 2.0.

[0119] In one or more embodiments, the cold flow resistance of the polymer can be measured using a Scott plasticity tester. The measurement of cold flow resistance can be performed by placing a weight on a cylindrical button prepared from a sample of the polymer. The preparation of the button of the polymer sample can be done by molding about 2.5 g of the polymer at 100 °C for 20 minutes to prepare a cylindrical button with a diameter of 15 mm and a height of 12 mm. After cooling the button to room temperature, the button can be removed from the mold. Then, the button can be placed in the Scott plasticity tester at room temperature and the test can be performed by applying a load of 49 N (5 kg) to the sample. After 8 minutes, the residual sample gauge (i.e., the thickness of the sample) can be measured. Generally, the residual sample gauge can be used as an indicator of the cold flow resistance of the polymer, and the higher the residual sample gauge, the better the cold flow resistance.

[0120] Polymer products manufactured according to one or more embodiments of the present invention may have the beneficial feature of cold flow resistance. This beneficial cold flow resistance can be expressed as at least a 10% increase in cold flow due to gravity, at least a 20% increase in other embodiments, at least a 30% increase in other embodiments, at least a 40% increase in other embodiments, at least an 80% increase in other embodiments, at least a 100% increase in other embodiments, at least a 200% increase in other embodiments, at least a 300% increase in other embodiments when compared to similar polymer compositions (i.e., cis-1,4-polybutadiene) that have not been treated with a Lewis acid according to aspects of the present invention. Note that the increased cold flow resistance is determined using a Scott tester and the above-described analysis. Industrial Use

[0121] The cis-1,4-polybutadiene polymer of the present invention is advantageous in that it is particularly useful for the preparation of rubber compositions that can be used in the manufacture of tire components. Rubber compounding techniques and the additives used in the art are generally disclosed in The Compounding and Vulcanization of Rubber, in Rubber Technology (2 nd Ed. 1973).

[0122] The preparation of the rubber composition can be carried out by using the polymer alone or together with other elastomers (i.e., polymers that can be vulcanized to form compositions having rubber or elastomeric properties). Other elastomers that may be used include natural and synthetic rubbers. Synthetic rubbers are typically obtained from the polymerization of conjugated diene monomers, the copolymerization of conjugated diene monomers with other monomers (e.g., vinyl-substituted aromatic monomers), or the copolymerization of ethylene with one or more α-olefins and optionally one or more diene monomers.

[0123] Exemplary elastomers include natural rubber, synthetic polyisoprene, polybutadiene, polyisobutylene-co-isoprene, neoprene, poly(ethylene-co-propylene), poly(styrene-co-butadiene), poly(styrene-co-isoprene), poly(styrene-co-isoprene-co-butadiene), poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene), polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, and mixtures thereof. These elastomers can have innumerable macromolecular structures, for example, linear, branched, and star-shaped structures.

[0124] The rubber composition may contain fillers, for example, inorganic and organic fillers. Examples of organic fillers include carbon black and starch. Examples of inorganic fillers include silica, aluminum hydroxide, magnesium hydroxide, mica, talc (magnesium silicate hydrate), and clay (aluminum silicate hydrate). Carbon black and silica are the most common fillers used in the manufacture of tires. In certain embodiments, a mixture of different fillers may be advantageously used.

[0125] In one or more embodiments, carbon black includes furnace black, channel black, and lamp black. More specific examples of carbon black include super abrasion furnace black, intermediate super abrasion furnace black, high abrasion furnace black, high speed extrusion furnace black, fine furnace black, semi-reinforcing furnace black, medium processing channel black, hard processing channel black, conductive channel black, and acetylene black.

[0126] In certain embodiments, the surface area (EMSA) of the carbon black is at least 20 m 2 / g, and in another embodiment, at least 35 m 2It may also be / g, and the surface area value can be determined by the cetyltrimethylammonium bromide (CTAB) technique in accordance with ASTM D-1765. The carbon black can be in pelletized form or in non-pelletized flocculent form. The preferred form of the carbon black may depend on the type of mixing equipment used to mix the rubber compound.

[0127] The amount of carbon black used in the rubber composition may be up to about 50 parts by weight per 100 parts by weight (phr) of rubber, and typically about 5 to about 40 phr.

[0128] Some commercially available silicas that can be used include Hi-Sil™ 215, Hi-Sil™ 233, and Hi-Sil™ 190 (PPG Industries, Inc.; Pittsburgh, Pa.). Other suppliers of commercially available silica include Grace Davison (Baltimore, Md.), Degussa Corp. (Parsippany, N.J.), Rhodia Silica Systems (Cranbury, N.J.), and J.M. Huber Corp. (Edison, N.J.).

[0129] In one or more embodiments, the silica can be characterized by its surface area, thereby providing a measure of its reinforcing properties. The Brunauer-Emmett-Teller (「BET」) method (described in J. Am. Chem. Soc., vol. 60, p. 309 et seq.) is a widely recognized method for determining surface area. The BET surface area of the silica is generally less than 450 m 2 / g. Useful ranges of surface area include about 32 to about 400 m 2 / g, about 100 to about 250 m 2 / g, about 150 to about 220 m 2 / g.

[0130] The pH of the silica is generally from about 5 to about 7. Or slightly higher than 7. In other embodiments, it is from about 5.5 to about 6.8.

[0131] In one or more embodiments, when using silica as a filler (alone or in combination with other fillers), a binder and / or a shielding agent may be added to the rubber composition during mixing to enhance the interaction between the silica and the elastomer. Useful binders and shielding agents are disclosed in the following documents. U.S. Patent Nos. 3,842,111; 3,873,489; 3,978,103; 3,997,581; 4,002,594; 5,580,919; 5,583,245; 5,663,396; 5,674,932; 5,684,171; 5,684,172; 5,696,197; 6,608,145; 6,667,362; 6,579,949; 6,590,017; 6,525,118; 6,342,552; and 6,683,135. These are incorporated herein by reference.

[0132] The amount of silica used in the rubber composition can be from about 1 to about 100 phr, or in other embodiments from about 5 to about 80 phr. The useful upper limit range is limited by the high viscosity imparted by the silica. When using silica together with carbon black, the amount of silica can be lowered to about 1 phr. Since the amount of silica is low, the amount of binder and shielding agent used can be reduced. Generally, the amount of binder and shielding agent ranges from about 4% to about 20% based on the weight of the silica used.

[0133] A number of rubber curing agents (also called vulcanizing agents) may be used, including sulfur or peroxide-based curing systems. The curing agents are described in Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 20, pgs. 365~468, (3rd Ed. 1982), in particular, Vulcanization Agents and Auxiliary Materials, pgs. 390~402, and A.Y. Coran, Vulcanization, Encyclopedia of Polymer Science and Engineering, (2 nd Ed. 1989), which are hereby incorporated by reference. The vulcanizing agents can be used alone or in combination.

[0134] Other components typically used in rubber compounding may also be added to the rubber composition. These include accelerators, activator accelerators, oils, plasticizers, waxes, scorch inhibitors, processing aids, zinc oxide, tackifying resins, reinforcing resins, fatty acids such as stearic acid, peptizing agents, anti-degradants such as antioxidants and anti-ozone agents. In certain embodiments, the oils used include those conventionally used as extender oils. This is as described above.

[0135] All components of the rubber composition can be mixed using standard mixing equipment such as a Banbury or Brabender mixer, an extruder, a kneader, and two rolling mills. In one or more embodiments, the components are mixed in two or more stages. In the first stage, often also called the masterbatch mixing stage, a so-called masterbatch (typically containing rubber components and fillers) is prepared. The vulcanizing agent may be excluded from the masterbatch to prevent premature vulcanization (also known as scorch). The masterbatch can be mixed at an initial temperature of about 25°C to about 125°C and a discharge temperature of about 135°C to about 180°C. Immediately after the masterbatch is prepared, the vulcanizing agent can be introduced into the masterbatch and mixed in a final mixing stage, typically at a relatively low temperature to reduce the likelihood of premature vulcanization. Optionally, an additional mixing stage, often called a remill, can be used between the masterbatch mixing stage and the final mixing stage. When silica is included as a filler in the rubber composition, one or more remill stages are often used. The addition of various components containing the polymer of the present invention can be carried out during these remills.

[0136] Mixing procedures and conditions particularly applicable to silica-filled tire formulations are described in U.S. Pat. Nos. 5,227,425, 5,719,207, and 5,717,022, and European Patent No. 890,606, all of which are incorporated herein by reference. In one embodiment, the first masterbatch is prepared by including the polymer and silica of the present invention in the substantial absence of a coupling agent and a shielding agent.

[0137] The rubber compositions prepared from the polymers of the present invention are particularly useful in forming tire components such as treads, subtreads, sidewalls, body ply skims, bead fillers, and the like. Preferably, the polymers of the present invention are used in tread formulations and sidewall formulations. In one or more embodiments, these tread or sidewall formulations may contain from about 10% to about 100% by weight, in other embodiments from about 35% to about 90% by weight, and in other embodiments from about 50% to about 80% by weight (based on the total weight of the rubber in the formulation) of the polymer.

[0138] When rubber compositions are used in the manufacture of tires, these compositions can be processed into tire components by conventional tire manufacturing techniques such as standard rubber shaping techniques, molding techniques, and curing techniques. Typically, vulcanization is achieved by heating the vulcanizable composition in a mold. For example, the mold may be heated to about 140°C to about 180°C. The cured or crosslinked rubber composition can be referred to as vulcanized rubber (generally containing a thermoset three-dimensional polymer network). Other components such as fillers and processing aids may be uniformly dispersed throughout the crosslinked network. Pneumatic tires can be made as described in U.S. Patent Nos. 5,866,171, 5,876,527, 5,931,211, and 5,971,046, which are incorporated herein by reference.

[0139] To illustrate the practice of the present invention, the following examples were prepared and tested. However, these examples should not be regarded as limiting the scope of the present invention. The claims define the present invention.

Examples

[0140] In the following examples, the Mooney viscosity (ML 1+4 ) of the polymer samples was determined at 100°C using a Monsanto Mooney viscometer with a large rotor, a preheating time of 1 minute, and an operating time of 4 minutes. The number average (M n ) and weight average (Mw )The molecular weight was determined by gel permeation chromatography (GPC). The GPC equipment was equipped with a differential refractive index (RI) detector and an ultraviolet (UV) absorption detector. The cis-1,4-bond, trans-1,4-bond, and 1,2-bond contents of the polymer sample were determined by infrared spectroscopy.

[0141] The cold flow resistance of the polymer was measured using a Scott plasticity tester as described above.

[0142] Example 1 Synthesis of Unmodified cis-1,4-Polybutadiene A nitrogen-purged sealed glass container was filled with 92.9 g of anhydrous hexane and 240.4 g of a 20.8 wt% butadiene solution in hexane. To this mixture, 2.81 mL of a 1.03 M triisobutylaluminum solution in hexane, 0.91 mL of a 0.093 M neodymium versatate solution in cyclohexane, and 0.76 mL of a 0.167 M ethylaluminum dichloride solution in hexane were sequentially added. The polymerization mixture was immediately placed in a stirred tank at 80 °C. After stirring for 50 minutes, the polymerization was stopped by filling the polymerization mixture with 3.0 mL of a 10 wt% 2,6-di-tert-butyl-4-methylphenol solution in isopropanol. The polymer was coagulated in 8 liters of isopropanol containing 15 g of 2,6-di-tert-butyl-4-methylphenol and then drum dried. Refer to Table 1 for the property evaluation data of the polymer.

[0143] Example 2 Synthesis of BF3·Bu2O-Modified cis-1,4-Polybutadiene A nitrogen-purged sealed glass container was filled with 92.9 g of anhydrous hexane and 240.4 g of a 20.8 wt% butadiene solution in hexane. To this mixture, 2.81 mL of a 1.03 M triisobutylaluminum solution in hexane, 0.91 mL of a 0.093 M neodymium versatate solution in cyclohexane, and 0.76 mL of a 0.167 M ethylaluminum dichloride solution in hexane were sequentially added. The polymerization mixture was immediately placed in a stirred tank at 80 °C. After stirring for 50 minutes, 1.70 mL of a 1.00 M BF3·Bu2O solution in hexane was charged and the polymerization solution was stirred at 50 °C to treat the polymer with a Lewis acid. After stirring for 30 minutes, the polymerization was terminated by charging the polymerization mixture with 3.0 mL of a 10 wt% 2,6-di-tert-butyl-4-methylphenol solution in isopropanol. The polymer was coagulated in 8 liters of isopropanol containing 15 g of 2,6-di-tert-butyl-4-methylphenol and then drum-dried. Refer to Table 1 for the characteristic evaluation data of the polymer.

[0144] Example 3 Synthesis of unmodified cis-1,4-polybutadiene A nitrogen-purged sealed glass container was filled with 92.9 g of anhydrous hexane and 240.4 g of a 20.8 wt% butadiene solution in hexane. The preparation of the preformed catalyst was carried out by mixing 6.31 mL of a 3.17 M methylaluminoxane solution in toluene, 1.53 mL of 21.4 wt% 1,3-butadiene in a hexane solution, 2.16 mL of a 0.093 M neodymium versatate solution in cyclohexane, 3.89 mL of a 1.09 M diisobutylaluminum hydride solution in hexane, and 0.80 mL of a 1.07 M diethylaluminum chloride solution in hexane. The catalyst was aged for 15 minutes, diluted with 6.00 mL of toluene, and then 2.59 mL of the catalyst solution was charged into the container containing butadiene and hexane. This polymerization mixture was immediately placed in a stirred tank at 65 °C. After stirring for 60 minutes, the polymerization was terminated by charging the polymerization mixture with 3.0 mL of a 10 wt% 2,6-di-tert-butyl-4-methylphenol solution in isopropanol. This polymer was coagulated in 8 liters of isopropanol containing 15 g of 2,6-di-tert-butyl-4-methylphenol and then drum dried. Refer to Table 1 for the property evaluation data of the polymer.

[0145] Example 4 Synthesis of BF3·Bu2O-Modified Cis-1,4-Polybutadiene A nitrogen-purged sealed glass container was filled with 92.9 g of anhydrous hexane and 240.4 g of a 20.8 wt% butadiene solution in hexane. The preparation of the preformed catalyst was carried out by mixing 6.31 mL of a 3.17 M methylaluminoxane solution in toluene, 1.53 mL of 21.4 wt% 1,3-butadiene in a hexane solution, 2.16 mL of a 0.093 M neodymium versatate solution in cyclohexane, 3.89 mL of a 1.09 M diisobutylaluminum hydride solution in hexane, and 0.80 mL of a 1.07 M diethylaluminum chloride solution in hexane. The catalyst was aged for 15 minutes, diluted with 6.00 mL of toluene, and then 2.59 mL of the catalyst solution was charged into the container containing butadiene and hexane. This polymerization mixture was immediately placed in a stirred tank at 65 °C. After stirring for 60 minutes, 2.00 mL of a 1.00 M BF3·Bu2O (boron trifluoride dibutyl ether compound) solution in hexane was charged and the polymerization solution was stirred at 50 °C to treat the polymer with a Lewis acid. After stirring for 30 minutes, the polymerization was terminated by charging 3.0 mL of a 10 wt% 2,6-di-tert-butyl-4-methylphenol solution in isopropanol into the polymerization mixture. This polymer was coagulated in 8 liters of isopropanol containing 15 g of 2,6-di-tert-butyl-4-methylphenol and then drum dried. Refer to Table 1 for the characteristic evaluation data of the polymer.

[0146] Table 1 summarizes and shows the characteristics of unmodified cis-1,4-polybutadiene and BF3·Bu2O-modified cis-1,4-polybutadiene. Unmodified control samples prepared using two different catalyst systems are shown in Examples 1 and 3. BF3·Bu2O-modified polymers prepared from the same two catalyst systems are shown in Examples 2 and 4.

[0147] From the data in Figure 1, it can be seen that the cis-1,4-polybutadiene sample modified with BF3·Bu2O (Example 2) shows a significantly higher residual sample gauge value at the same polymer Mooney viscosity compared to the unmodified polymer, and as a result, shows significantly better cold flow resistance.

[0148] From the data in Figure 2, it can be seen that the cis-1,4-polybutadiene sample modified with BF3·Bu2O (Example 4) shows a significantly higher residual sample gauge value at the same polymer Mooney viscosity compared to the unmodified polymer, and as a result, shows significantly better cold flow resistance.

[0149] [Table 1]

[0150] Various modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The present invention is not formally limited to the exemplary embodiments described herein.

Claims

Claim 1 A method for preparing a cis-1,4-polybutadiene having useful resistance to cold flow, comprising: (i) preparing a preformed catalyst by combining (a) a lanthanide-containing compound, (b) an alkylating agent, and (c) a halogen source, and aging the preformed catalyst for 6 days or more; (ii) preparing a polymerization mixture by combining the preformed catalyst and butadiene to form an active polymerization mixture containing a reactive polymer having diene reactivity; (iii) bringing the active polymerization mixture containing the reactive polymer having diene reactivity to a peak polymerization temperature; (iv) in step (iii), after the active polymerization mixture containing the reactive polymer having diene reactivity reaches the peak polymerization temperature, adding a Lewis acid to the active polymerization mixture containing the reactive polymer having diene reactivity, and directly treating the reactive polymer having diene reactivity with the Lewis acid. The method according to claim 1, wherein step (iv) is carried out at 10°C to 150°C, and the Lewis acid and the reactive polymer having diene reactivity are aged for 1 hour or more before any quenching of the active polymerization mixture. Claim 2 The method according to claim 1, wherein the preformed catalyst is aged for 12 days or more. Claim 3 The method according to claim 1, wherein step (iv) is carried out at 20°C to 100°C. Claim 4 The method according to claim 1, wherein the preformed catalyst comprises a lanthanide carboxylate, an aluminum hydride, and an organometallic halide. Claim 5 The method according to claim 1, wherein step (ii) is carried out in a polymerization mixture containing less than 20% by weight of an organic solvent. Claim 6 The method according to claim 1, further comprising adding a functionalizing agent to the active polymerization mixture containing the reactive polymer having diene reactivity. Claim 7 The method according to claim 1, further comprising adding a coolant to the active polymerization mixture containing the reactive polymer having diene reactivity.

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