Polydienes with reduced solution viscosity

Abstract

To provide a polydiene with improved processability while maintaining and / or enhancing the performance of a downstream product incorporating such polydiene.SOLUTION: There is provided a 1,4-cis polydiene formed by polymerizing at least a 1,3-butadiene monomer in the presence of a lanthanide catalyst system and a bis-diene additive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to polydienes having reduced solution viscosity. [Background technology]

[0002]

[0001] The use of polybutadiene, polyisoprene, polystyrene, and their copolymers is well known in the rubber and tire industries. Polybutadienes with a high 1,4-cis content, when cured, impart unique performance properties to downstream products. 1,4-cis polydienes formed with lanthanide-based (also known as rare earth) catalyst systems contain a linear backbone and are believed to offer better tensile properties, higher wear resistance, lower hysteresis, and better fatigue resistance compared to 1,4-cis polydienes prepared with other catalyst systems.

[0003]

[0002] Currently, high 1,4-cis content polybutadiene is produced almost exclusively using rare earth transition metal catalysts, such as neodymium. Despite their advantages, the use of such catalysts in the production of high 1,4-cis content polybutadiene presents several challenges, including high solution viscosity, low solids production rate, fouling, and high cold flow. Due to the increasing industrial demand for this rubber, nearly all high 1,4-cis polydiene production facilities are facing these challenges.

[0004]

[0003] Efforts have been made to ameliorate these problems. For example, U.S. Patent No. 10,316,121 discloses the use of a specific Lewis acid additive in a polymerization system containing activated cement to prepare, with a lanthanide-based catalyst and a conjugated diene monomer, a high 1,4-cis polydiene having useful resistance to cold flow.

[0005]

[0004] U.S. Patent No. 6,576,731 discloses a specific reagent for reducing the solution viscosity / Mooney viscosity ratio in the preparation of polybutadiene with a lanthanide-based catalyst. The reagent is a specific silane used as an intermediate for the preparation of polybutadiene.

[0006] It has now been discovered that the addition of a bisdiene additive to the preparation of high 1,4-cis polydienes desirably facilitates a reduction in the ratio of solution viscosity to Mooney viscosity. The present disclosure further relates to the method by which the polydiene compositions are synthesized. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 10,316,121 [Patent Document 2] U.S. Patent No. 6,576,731 [Patent Document 3] U.S. Patent No. 6,242,534 [Patent Document 4] U.S. Patent No. 6,207,757 [Patent Document 5] U.S. Patent No. 6,133,364 [Patent Document 6] U.S. Patent No. 6,372,857 [Patent Document 7] U.S. Patent No. 5,395,891 [Patent Document 8] U.S. Patent No. 6,127,488 [Patent Document 9] U.S. Patent No. 5,672,639 [Patent Document 10] U.S. Patent No. 6,608,125 [Patent Document 11] U.S. Patent No. 6,849,754 [Non-patent literature]

[0008] [Non-Patent Document 1] Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000 Parts, 2003, 62nd Edition, published by the Institute of British Petroleum (UK) [Non-patent document 2] Journal of the American Chemical Society, Volume 60, Page 304 (1930) [Non-patent document 3] The Vanderbilt Rubber Handbook (1978), pp. 344-346 Summary of the Invention [Means for solving the problem]

[0009] The present invention provides polydienes with improved processability that maintain and / or enhance the performance of downstream products incorporating such polydienes. The improved processability and performance is achieved by adding bis-dienes via comonomers.

[0010]

[0007] One or more embodiments of this disclosure relate to a method for preparing cis-polydienes having reduced SSV / Mooney ratios. According to the contemplated method, a 1,4-cis-polydiene preparation system is prepared by introducing a lanthanide-based catalyst and a conjugated diene monomer to either (A) a carbon-bridged bis-diene compound or (B) a heteroatom-bridged bis-diene compound.

[0011]

[0008] The present disclosure also relates to branched functionalized polymers defined by the formula: P-(CH2) n -X-(CH2) m -P wherein m+n is greater than 2 and P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%. In one embodiment, X is individually -CR2-, and R is hydrogen, fluoride, alkyl, cycloalkyl, or aryl, or a combination thereof.

[0012] In other embodiments, X is -SiR2-, where R is hydrogen, alkyl, aryl, alkoxy, aryloxy, a monovalent organic group, or a combination thereof.

[0013] In another embodiment, X is [ka] [In the formula, R is hydrogen, alkyl, aryl, alkyloxy, aryloxy, or a monovalent organic group, or a combination thereof, and t is 1 to 8.]

[0014] In another embodiment, X is -PR- and R is alkyl or aryl.

[0015] In other embodiments, X is -P(O)R-, where R is alkyl or aryl.

[0016] In another embodiment, X is [ka] [wherein t+g is greater than 2]

[0017] In other embodiments, X is an ethylene oxide group or a propylene oxide group.

[0018] Another embodiment of this disclosure also provides a branched functionalized polymer defined by the formula: P-(CH2) n -Y-(CH2) m -P wherein m+n is greater than 2, Y is sulfur or other chalcogen, and P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0019]

[0016] According to an embodiment of this disclosure, the method includes preparing a long-chain polymer by linking two polymer chains with a diene containing carbon or heteroatoms, and the reactor system is batch or continuous, or a mixture of the two. DETAILED DESCRIPTION OF THE INVENTION

[0020] It has now been discovered that the incorporation of bis-dienes into 1,4-cis polydiene polymers is, at least in part, the basis for producing 1,4-cis polydienes with reduced solution viscosity. Another aspect of the present invention is 1,4-cis polydienes produced using functionalized bis-diene additives. Contemplated bis-dienes include organic functional groups having sulfur, oxygen, silicon, or phosphorus atoms and are used in the presence of a lanthanide-based catalyst. The incorporation of one or more of the disclosed bis-dienes promotes long-chain branching of the 1,4-cis polydienes, which may or may not be functionalized, while desirably reducing the number of process steps, minimizing by-product waste, and eliminating the need for additional additives.

[0021]

[0018] One or more embodiments of this disclosure provide a method for preparing a branched 1,4-cis polydiene using a lanthanide-based catalyst, where the catalyst itself is prepared by incorporation of a bisdiene therein. Another embodiment of the present invention provides a method for preparing a heteroatom-functionalized polymer, the method comprising the steps of: (A) preparing a polymerization system comprising a branched 1,4-cis polydiene by introducing a lanthanide-based catalyst, a bisdiene, and a conjugated diene monomer; and (B) adding the heteroatom-containing bisdiene to the polymerization system comprising the cis-1,4-polydiene.

[0022] Generally speaking, branched polymers exhibiting reduced solution viscosity according to the present invention can be prepared by combining a diene monomer and a lanthanide-based catalyst with a bisdiene additive either before or during the initiation of polymerization of the 1,4-cis polydiene.

[0023] I. Diene Monomers Cis-1,4-polydienes can be prepared by polymerizing conjugated diene monomers using the disclosed catalyst systems. Many types of unsaturated monomers containing carbon-carbon double bonds can be polymerized into polymers using such metal catalysts. Elastomers or rubbery polymers can be synthesized by polymerizing diene monomers using this type of metal initiator system. The diene monomers that can be polymerized into synthetic rubbery polymers can be either conjugated or non-conjugated diolefins. Conjugated diolefin monomers containing 4 to 8 carbon atoms are generally preferred. Vinyl-substituted aromatic monomers can also be copolymerized with one or more diene monomers to form rubbery polymers, such as styrene-butadiene rubber (SBR). Some representative examples of conjugated diene monomers that can be polymerized into rubbery polymers include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-phenyl-1,3-butadiene, and 4,5-diethyl-1,3-octadiene. Some representative examples of vinyl-substituted aromatic monomers which can be utilized in the synthesis of rubbery polymers include styrene, 1-vinylnaphthalene, 3-methylstyrene, 3,5-diethylstyrene, 4-propylstyrene, 2,4,6-trimethylstyrene, 4-dodecylstyrene, 3-methyl-5-normal-hexylstyrene, 4-phenylstyrene, 2-ethyl-4-benzylstyrene, 3,5-diphenylstyrene, 2,3,4,5-tetraethylstyrene, 3-ethyl-1-vinylnaphthalene, 6-isopropyl-1-vinylnaphthalene, 6-cyclohexyl-1-vinylnaphthalene, 7-dodecyl-2-vinylnaphthalene, α-methylstyrene, and the like.

[0024]

[0021] There are no limitations herein on the diene monomer used. In one embodiment, the monomer may be 1,3-butadiene, which can be used to polymerize cis-1,4-polybutadiene.

[0025] II. Catalytic Systems The invention disclosed herein is not necessarily limited to a particular lanthanide-based catalyst system. In an embodiment of the present disclosure, the catalyst system used in the process of the present invention is prepared by preforming three catalyst components: (1) an alkylating agent, (2) a lanthanide-containing compound, and (3) a halogen source. In other embodiments, a compound containing a non-coordinating anion can be used as the halogen source. In the solution polymerization of the present invention, a polymerization medium comprising (4) an organic solvent can also be used.

[0026] A preferred catalyst component comprises (1) an organoaluminum compound, (2) a neodymium carboxylate, and (3) a dialkylaluminum chloride. In preparing the neodymium catalyst system, the neodymium carboxylate and the organoaluminum compound are first reacted together in the presence of isoprene for 10 to 30 minutes to produce the neodymium-aluminum catalyst component. In preparing the neodymium-aluminum catalyst component, the neodymium carboxylate and the organoaluminum compound are preferably reacted for 12 to 30 minutes, more preferably for 15 to 25 minutes.

[0027] The neodymium-aluminum catalyst component is then reacted with a dialkylaluminum chloride for a period of at least 30 minutes to produce a neodymium catalyst system. The activity of the neodymium catalyst system typically improves with increasing time given to this step, up to about 24 hours. Increasing the aging time beyond 24 hours typically does not result in higher catalyst activity. However, the catalyst system can be aged for much longer periods of time before use without any adverse consequences.

[0028] Neodymium catalyst systems are typically preformed at temperatures ranging from about 0° C. to about 100° C. More typically, neodymium catalyst systems are prepared at temperatures ranging from about 10° C. to about 60° C. Neodymium catalyst systems are preferably prepared at temperatures ranging from about 15° C. to about 30° C.

[0029] The organoaluminum compound contains at least one carbon-aluminum bond and can be represented by the following structural formula: [ka] [In the formula, R 1 is selected from the group consisting of alkyl groups (including cycloalkyl groups), alkoxy groups, aryl groups, alkaryl groups, arylalkyl groups, and hydrogen; R 2 is selected from the group consisting of alkyl groups (including cycloalkyl groups), aryl groups, alkaryl groups, arylalkyl groups, and hydrogen; R 3 is selected from the group consisting of alkyl groups (including cycloalkyl groups), aryl groups, alkaryl groups, and arylalkyl groups.

[0030] Representative compounds that meet this definition include diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, diphenylaluminum hydride, di-p-tolylaluminum hydride, dibenzylaluminum hydride, phenylethylaluminum hydride, phenyl-n-propylaluminum hydride, p-tolylethylaluminum hydride, p-tolyl-n-propylaluminum hydride, p-tolylisopropylaluminum hydride, benzylethylaluminum hydride, benzyl-n-propylaluminum hydride, and benzylisopropylaluminum hydride, as well as other organoaluminum hydrides. Also included are ethylaluminum dihydride, butylaluminum dihydride, isobutylaluminum dihydride, octylaluminum dihydride, amylaluminum dihydride, and other organoaluminum dihydrides. Also included are diethylaluminum ethoxide and dipropylaluminum ethoxide. Also included are trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum, triphenylaluminum, tri-p-tolylaluminum, tribenzylaluminum, ethyldiphenylaluminum, ethyl-di-p-tolylaluminum, ethyldibenzylaluminum, diethylphenylaluminum, diethyl-p-tolylaluminum, and diethylbenzylaluminum, as well as other triorganoaluminum compounds.

[0031] Neodymium carboxylates utilize organic monocarboxylic acid ligands containing 1 to 20 carbon atoms, such as acetic acid, propionic acid, valeric acid, hexanoic acid, 2-ethylhexanoic acid, neodecanoic acid, lauric acid, stearic acid, and the like, and include neodymium naphthenate, neodymium neodecanoate, neodymium octanoate, and other neodymium metal complexes with carboxylic acid-containing ligands containing 1 to 20 carbon atoms.

[0032] The proportions of catalyst components utilized in preparing the neodymium catalyst system of the present invention can vary widely. The atomic ratio of halide ion to neodymium metal can vary from about 0.1 / 1 to about 6 / 1. A more preferred ratio is from about 0.5 / 1 to about 3.5 / 1, with a most preferred ratio being about 2 / 1. The molar ratio of trialkylaluminum or alkylaluminum hydride to neodymium metal can range from about 4 / 1 to about 200 / 1, with a most preferred range being from about 8 / 1 to about 100 / 1. The molar ratio of isoprene to neodymium metal can range from about 0.2 / 1 to 3000 / 1, with a most preferred range being from about 5 / 1 to about 500 / 1.

[0033] The amount of catalyst used to initiate polymerization can vary over a wide range. A low concentration catalyst system is usually desirable to minimize ash problems. Polymerization has been found to occur when the neodymium metal catalyst level varies between 0.05 and 1.0 millimoles of neodymium metal per 100 grams of monomer. A preferred ratio is between 0.1 and 0.3 millimoles of neodymium metal per 100 grams of monomer.

[0034] Of course, the concentration of the total catalyst system used will depend on factors such as the purity of the system, the desired rate of polymerization, the temperature, and others, so no specific concentration can be stated other than to say that a catalytic amount is used.

[0035] The temperature at which the polymerization reaction is carried out can vary over a wide range. Typically, the temperature can range from very low, such as -60°C, to high, for example, 150°C or higher. Thus, temperature is not a critical factor in the present invention. However, it is generally preferred to carry out the reaction at a temperature within the range of about 10°C to about 90°C. The pressure at which the polymerization is carried out can also vary over a wide range. The reaction can be carried out at atmospheric pressure, or, if desired, below or above atmospheric pressure. Generally, satisfactory polymerizations are obtained when the reaction is carried out at about the autogenous pressure developed by the reactants under the operating conditions used.

[0036] The polymerization can be terminated by the addition of an alcohol, an acid, or another proton source, such as water. Such a termination step results in the formation of a protonic acid. However, it has been unexpectedly discovered that better color can be obtained by utilizing an alkaline aqueous neutralizer solution to terminate the polymerization. Another advantage of using an alkaline aqueous neutralizer solution to terminate the polymerization is that no residual organic material is added to the polymerization product.

[0037] Polymerization can be stopped by simply adding an alkaline aqueous neutralizer solution to the polymer cement. The amount of alkaline aqueous neutralizer solution added is typically in the range of about 1 weight percent to about 50 weight percent, based on the weight of the polymer cement. More typically, the amount of alkaline aqueous neutralizer solution added is in the range of about 4 weight percent to about 35 weight percent, based on the weight of the polymer cement. Preferably, the amount of alkaline aqueous neutralizer solution added is in the range of about 5 weight percent to about 15 weight percent, based on the weight of the polymer cement.

[0038] The alkaline aqueous neutralizer solution typically has a pH in the range of 7.1 to 9.5. More typically, the alkaline aqueous neutralizer solution has a pH in the range of 7.5 to 9.0, preferably 8.0 to 8.5. The alkaline aqueous neutralizer solution is generally a solution of an inorganic base, such as sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, potassium phosphate, or the like. For example, the alkaline aqueous neutralizer solution can be a 0.25 weight percent aqueous solution of sodium bicarbonate. Because the alkaline aqueous neutralizer solution is insoluble in the polymer cement, it is important to utilize a significant level of agitation to mix the alkaline aqueous neutralizer solution throughout the polymer cement to terminate the polymerization. Because the alkaline aqueous neutralizer solution is insoluble in the polymer cement, it quickly separates after agitation is discontinued.

[0039] The 1,4-cis polydienes of the present invention are prepared by solution polymerization in the presence of a neodymium catalyst system. Such polymerizations are typically carried out in a hydrocarbon solvent, which may be one or more aliphatic, aromatic, paraffinic, or cycloparaffinic compounds. These solvents usually contain from 4 to 10 carbon atoms per molecule and are liquid under the conditions of the polymerization. Some representative examples of suitable organic solvents include pentane, isooctane, cyclohexane, normal hexane, benzene, toluene, xylene, ethylbenzene, and the like, alone or in admixture.

[0040] Catalyst systems that can be used in one or more embodiments of the present invention are commercially available. For example, useful preformed catalyst systems are available under the trade names COMCAT Nd-FC(NH), COMCAT Nd-FC / 20(NH), and COMCAT Nd-FC / SF (COMAR CHEMICALS (Pty) Ltd).

[0041] III. Bisdiene Additives As used herein, "bisdiene" refers to a compound containing at least two diene groups bonded together by carbon or heteroatoms, or a combination thereof.

[0042] In one or more embodiments, the 1,4-cis polydiene-containing bis-diene compound may be defined by Formula I: P-(CH2) n -X-(CH2) m -P (I) wherein m+n is greater than 2, and each X is an aliphatic hydrocarbon group, an alicyclic hydrocarbon, an aliphatic perfluorocarbon, or an aromatic hydrocarbon, or a combination thereof. P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0043] In one or more embodiments, the 1,4-cis polydiene-containing bis-diene compound may be defined by Formula II: P-(CH2) n -Y-(CH2) m -P (II) wherein m+n is greater than 2 and Y is sulfur or other chalcogen. P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0044] In one or more embodiments, the 1,4-cis polydiene-containing bis-diene compound may be defined by Formula III: P-(CH2) n -Z-(CH2) m -P (III) wherein m+n is greater than 2, Z is -SiR2-, -GeR2-, or -SnR2-, and R is hydrogen, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a monovalent organic group, or a combination thereof. P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0045] In one or more embodiments, the 1,4-cis polydiene-containing bis-diene compound may be defined by Formula IV: P-(CH2) n -T-(CH2) m -P (IV) wherein m+n is greater than 2 and T is a siloxane group. [ka] wherein R is hydrogen, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, a monovalent organic group, or a combination thereof, and t is 1 to 8. P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0046] In one or more embodiments, the 1,4-cis polydiene-containing bis-diene compound may be defined by Formula V: P-(CH2) n -G-(CH2) m -P (V) [In the formula, m+n is greater than 2, and G is an alkylphosphine group, an arylphosphine group, an alkylphosphine oxide group, or an arylphosphine oxide group.] P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0047] In one or more embodiments, the 1,4-cis polydiene-containing bis-diene compound may be defined by Formula VI: P-(CH2) n -H-(CH2) m -P (VI) wherein m+n is greater than 2 and H is [ka] and t+g is greater than 2.] P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0048] In one or more embodiments, the 1,4-cis polydiene-containing bis-diene compound may be defined by Formula VII: P-(CH2) n -L-(CH2) m -P (VII) wherein m+n is greater than 2 and L can be an ethylene oxide group or a propylene oxide group. P is a 1,4-cis polydiene polymer chain having a 1,4-cis bond content greater than 90%.

[0049] In one or more embodiments, the bisdiene compound may be added after at least 50%, in other embodiments at least 60%, in other embodiments at least 70%, in other embodiments at least 80%, in other embodiments at least 90%, and in other embodiments at least 95% monomer conversion.

[0050] In one or more embodiments, the bis-diene compound may be added to the lanthanide-based catalyst system, or the entire catalyst mixture may be used as the lanthanide-based catalyst system.

[0051] In one or more embodiments, the bis-diene compound may be added to a different reactor where polymerization is initiated.

[0052] In one or more embodiments, the amount of bisdiene compound used to prepare the branched polydienes of the present invention can be expressed in terms of the amount of polymer present in the polymerization mixture. In one or more embodiments, the amount of bisdiene used is at least 1 mmol, in one or more embodiments at least 2 mmol, in one or more embodiments at least 3 mmol, in one or more embodiments at least 5 mmol, and in one or more embodiments at least 7 mmol per 1500 g of 1,4-cis polydiene. In contemplated embodiments, the bisdiene is added at anywhere from 0% to 95% monomer conversion.

[0053] Representative examples of suitable bisdienes bridged with an aliphatic hydrocarbon group, an alicyclic hydrocarbon, an aliphatic perfluorocarbon, or an aromatic hydrocarbon, or a combination thereof, include 3,6-dimethyleneocta-1,7-diene, 3,7-dimethylenenona-1,8-diene, 3,8-dimethylenedeca-1,9-diene, 3,9-dimethylenedeca-1,10-diene, 3,10-dimethylenedodeca-1,11-diene, 3,11-dimethylenedodeca-1,12-diene, 3,12-dimethylenetetradeca-1,13-diene, 3,13-dimethylenedicarboxylic acid esters, 3,14-dimethylenedicarboxylic acid esters, 3,15-dimethylenedicarboxylic acid esters, 3,16-dimethylenedicarboxylic acid esters, 3,17-dimethylenedicarboxylic acid esters, 3,18-dimethylenedicarboxylic acid esters, 3,19-dimethylenedicarboxylic acid esters, 3,20-dimethylenedicarboxylic acid esters, 3,21-dimethylenedicarboxylic acid esters, 3,22-dimethylenedicarboxylic acid esters, 3,23-dimethylenedicarboxylic acid esters, 3,24-dimethylenedicarboxylic acid esters, 3,25-dimethylenedicarboxylic acid esters, 3,26-dimethylenedicarboxylic acid esters, 3,27-dimethylenedicarboxylic acid esters, 3,28-dimethylenedicarboxylic acid esters, 3,29-dimethylenedicarboxylic acid esters, 3,30-dimethylenedicarboxylic acid esters, 3,31-dimethylenedicarboxylic acid esters, 3,32-dimethylenedicarboxylic acid esters, 3,33-dimethylenedicarboxylic acid esters, 3,34-dimethylenedicarboxylic acid esters, 3,35-dimethylened Methylenepentadeca-1,14-diene, 3,14-dimethylenehexadeca-1,15-diene, 3,15-dimethyleneheptadeca-1,16-diene, 3,16-dimethyleneoctadeca-1,17-diene, 3,17-dimethylenenonadeca-1,18-diene, 3,18-dimethyleneicosa-1,19-diene, 3,19-dimethylenehenicosa-1,20-diene, 3,20-dimethylenedocosa-1,21-diene, 7,10-dimethylene-7-vinyl-m-menth-8-ene, 1,3-bis(2-methylenebut-3-enyl)cyclohexane, 1, 3-Bis(3-methylenepent-4-enyl)cyclohexane, 3-methylene-6-[3-(4-methylenehex-5-enyl)cyclohexyl]hex-1-ene, 3-methylene-7-[3-(5-methylenehept-6-enyl)cyclohexyl]hept-1-ene, 7,10-dimethylene-7-vinyl-p-menth-8-ene, 1,4-bis(2-methylenebut-3-enyl)cyclohexane, 3-methylene-6-[4-(4-methylenehex-5-enyl)cyclohexyl]hex-1-ene, 3-methylene-7-[4-(5-methylenehept-6 -enyl)cyclohexyl]hept-1-ene, 1,3-bis(2-methylenebut-3-enyl)benzene, 1,4-bis(3-methylenepent-4-enyl)benzene, 3-methylene-7-[4-(5-methylenehept-6-enyl)phenyl]hept-1-ene, 1,3-bis(2-methylenebut-3-enyl)benzene, 1,3-bis(3-methylenepent-4-enyl)benzene, 3-methylene-6-[3-(4-methylenehex-5-enyl)phenyl]hex-1-ene, 4,4,5,5-tetrafluoro-3,6-dimethyleneocta-1,7-diene, 4,4,5,5,6,6-hexafluoro-3,7-dimethylenenona-1,8-diene, 4,4,5,5,6,6,7,7-octafluoro-3,8-dimethylendeca-1,9-diene, 4,4,5,5,6,6,7,7,8,8-decafluoro-3,9-dimethylendeca-1,10-diene, 4,4,5,5,6,6,7,7,8,8,9,9-dodecafluoro Fluoro-3,10-dimethylendodeca-1,11-diene, 5,5,6,6-tetrafluoro-3,8-dimethylendodeca-1,9-diene, 5,5,6,6,7,7-hexafluoro-3,9-dimethylendodeca-1,10-diene, 5,5,6,6,7,7,8,8-octafluoro-3,10-dimethylendodeca-1,11-diene, 5,5,6,6,7,7,8,8 9,9-Decafluoro-3,11-dimethylenetrideca-1,12-diene, 5,5,6,6,7,7,8,8,9,9,10,10-Dodecafluoro-3,12-dimethylenetetradeca-1,13-diene, 3,10-dimethylendodeca-1,6,11-triene, 3,12-dimethylenetetradeca-1,7,13-triene, 3,14-dimethylenehexadeca-1,8,1 5-triene, 3,16-dimethyleneoctadeca-1,9,17-triene, 3,18-dimethyleneicosa-1,10,19-triene, 3,20-dimethylenedocosa-1,11,21-triene, (6E)-3,10-dimethylenedodeca-1,6,11-triene, and (6Z)-3,10-dimethylenedodeca-1,6,11-triene.

[0054] Representative examples of suitable bisdienes bridged by sulfur and other chalcogens, or combinations thereof, include, but are not limited to, 2-(1-methyleneprop-2-enyldithio)buta-1,3-diene, 2-[(2-methylenebut-3-enyldithio)methyl]buta-1,3-diene, 3-methylene-5-(3-methylenepent-4-enyldithio)pent-1-ene, 3-methylene-6-(4-methylenehex-5-enyldithio)hex-1-ene, and 3-methylene-7-(5-methylenehept-6-enyldithio)hept-1-ene.

[0055] Representative examples of suitable bisdienes crosslinked with silanes or siloxanes include, but are not limited to, dimethylbis(1-methyleneprop-2-enyl)silane, dimethylbis(2-methylenebut-3-enyl)silane, dimethylbis(3-methylenepent-4-enyl)silane, dimethoxybis(1-methyleneprop-2-enyl)silane, dimethoxybis(2-methylenebut-3-enyl)silane, dimethoxybis(3-methylenepent-4-enyl)silane, [dimethyl(1-methyleneprop-2-enyl)siloxy]bis(methyl)(1-methyleneprop-2-enyl)silane, [dimethyl(2-methylenebut-3-enyl)siloxy]bis(methyl)(2-methylenebut-3-enyl)silane.

[0056] Representative examples of suitable bisdienes bridged by phosphines or phosphine oxides include, but are not limited to, methylbis(1-methyleneprop-2-enyl)phosphine, bis(1-methyleneprop-2-enyl)(phenyl)phosphine, methylbis(1-methyleneprop-2-enyl)phosphine oxide, bis(1-methyleneprop-2-enyl)(phenyl)phosphine oxide, methylbis(2-methylenebut-3-enyl)phosphine, bis(2-methylenebut-3-enyl)(phenyl)phosphine, methylbis(2-methylenebut-3-enyl)phosphine oxide, bis(2-methylenebut-3-enyl)(phenyl)phosphine oxide. Representative examples of suitable bisdienes bridged by epoxides include, but are not limited to, 2,3-bis(2-methylenebut-3-enyl)oxirane, 2,3-bis(3-methylenepent-4-enyl)oxirane, and 2,3-bis(4-methylenehex-5-enyl)oxirane.

[0057] Representative examples of suitable bridged bisdienes are 3-methylene-5-[2-(3-methylenepent-4-enyloxy)ethoxy]pent-1-ene, 3-methylene-6-[2-(4-methylenehex-5-enyloxy)ethoxy]hex-1-ene, 3-methylene-7-[2-(5-methylenehept-6-enyloxy)ethoxy]hept-1-ene, 3-methylene-8-[2-(6-methyleneoct-7-enyloxy)ethoxy]hept-1-ene, ]oct-1-ene, 14-methylene-2-vinyl-5,8,11-trioxahexadeca-1,15-diene, 16-methylene-2-vinyl-6,9,12-trioxaoctadeca-1,17-diene, 18-methylene-2-vinyl-7,10,13-trioxaicosa-1,19-diene, 20-methylene-2-vinyl-8,11,14-trioxadocosa-1,21-diene.

[0058] Final polymer In one or more embodiments, the final polymers may have a 1,2-bond content of less than 1.5%. This percentage is based on the number of diene mer units incorporating 1,2-bonds relative to the total number of diene mer units. In one or more embodiments, these polymers may have a 1,2-bond content of about 0.05% to about 1.5%. The cis-1,4-bond content, cis-1,2-bond content, and trans-1,4-bond content may be determined by infrared spectroscopy.

[0059] In one or more embodiments, the number average molecular weight (Mn) of the cis-1,4-polydiene polymers can be from about 25,000 to about 700,000, more preferably from about 50,000 to about 350,000, and most preferably from about 125,000 to about 250,000, as measured using size exclusion chromatography (SEC). In contemplated embodiments, the 1,4-cis polydienes are characterized by a Mooney viscosity measurement (ML1+4 at 100°C) of from about 15 to about 90, and most preferably from 40 to about 65.

[0060] In one embodiment, the polymer can be a 1,4-cis polybutadiene rubber (BR). The BR can be conveniently characterized, for example, by having at least a 90 percent cis 1,4-content. In one embodiment, the polymer is functionalized. In another embodiment, the polymer is not functionalized.

[0061] The final polymer may be compounded into a rubber composition. The rubber composition may optionally contain, in addition to the polymer, one or more olefinically unsaturated rubbers or elastomers. The phrase "olefinically unsaturated rubber or elastomer" or "diene-based elastomer" is intended to include both natural rubber and its various raw and reclaim forms, as well as various synthetic rubbers. In describing this invention, the terms "rubber" and "elastomer" may be used interchangeably unless otherwise indicated. The terms "rubber composition," "compounded rubber," and "rubber compound" are used interchangeably and refer to rubbers in which various components and materials have been blended or mixed; such terms are well known to those skilled in the art of rubber mixing or compounding. Representative synthetic polymers are the homopolymerization products of butadiene and its homologs and derivatives, such as methylbutadiene, dimethylbutadiene, and pentadiene, as well as copolymers such as those formed from butadiene, or its homologs or derivatives, with other unsaturated monomers. Among the other unsaturated monomers are acetylenes, such as vinyl acetylene; olefins, such as isobutylene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds, such as acrylic acid, acrylonitrile (which polymerizes with butadiene to form NBR), methacrylic acid, and styrene (which polymerizes with butadiene to form SBR), as well as vinyl esters and various unsaturated aldehydes, ketones, and ethers, such as acrolein, methyl isopropenyl ketone, and vinyl ethyl ether.Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), butyl rubber, halobutyl rubber, such as chlorobutyl or bromobutyl rubber, styrene / isoprene / butadiene rubber, copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile, and methyl methacrylate, and ethylene / propylene terpolymers, also known as ethylene / propylene / diene monomer (EPDM), particularly ethylene / propylene / dicyclopentadiene terpolymers. Additional examples of rubbers that can be used include alkoxy-silyl end-functionalized solution-polymerized polymers (SBR, PBR, IBR, and SIBR), silicon-coupled and tin-coupled star-branched polymers. Preferred rubbers or elastomers are polyisoprene (natural or synthetic), polybutadiene, and SBR.

[0062] In one embodiment, the at least one additional rubber is preferably at least two of diene-based rubbers, for example, a combination of two or more rubbers, such as cis 1,4-polyisoprene rubber (natural or synthetic, preferably natural), 3,4-polyisoprene rubber, styrene / isoprene / butadiene rubber, emulsion and solution polymerization derived styrene / butadiene rubber, cis 1,4-polybutadiene rubber, and emulsion polymerization prepared butadiene / acrylonitrile copolymer.

[0063] In one embodiment of the present invention, emulsion polymerization-derived styrene / butadiene (E-SBR) may be used, which has a relatively common bound styrene content of from about 20 to about 28 percent, or for some applications, E-SBR having a moderate to relatively high bound styrene content, i.e., from about 30 to about 45 percent bound styrene.

[0064] Emulsion polymerization-prepared E-SBR refers to copolymerization of styrene and 1,3-butadiene as an aqueous emulsion. Such copolymerization is well known to those skilled in the art. The bound styrene content can vary, for example, from about 5 to about 50 percent. In one embodiment, the E-SBR may also contain acrylonitrile, for example, in an amount of from about 2 to about 30 weight percent bound acrylonitrile in the terpolymer, to form a terpolymer rubber as an E-SBAR.

[0065] Emulsion polymerization prepared styrene / butadiene / acrylonitrile copolymer rubbers containing from about 2 to about 40 weight percent bound acrylonitrile in the copolymer are also contemplated as diene-based rubbers for use in this invention.

[0066] Solution polymerization prepared SBR (S-SBR) typically has a bound styrene content within the range of about 5 to about 50 percent, preferably about 9 to about 36 percent. S-SBR can be conveniently prepared, for example, by organolithium catalysis in the presence of an organic hydrocarbon solvent.

[0067] In one embodiment, additional cis 1,4-polybutadiene rubber (BR) may be used.

[0068]

[0065] Cis 1,4-polyisoprene and cis 1,4-polyisoprene natural rubber are well known to those having skill in the rubber art.

[0069]

[0066] As used herein, and according to conventional practice, the term "phr" refers to "parts by weight of a respective material per 100 parts by weight of rubber or elastomer."

[0070] The rubber composition may also contain up to 70 phr of processing oil. The processing oil may be included in the rubber composition as an extender oil, typically used to extend the elastomer. The processing oil may also be included in the rubber composition by adding the oil directly during rubber compounding. The processing oil used may include both the extender oil present in the elastomer and the processing oil added during compounding. Suitable processing oils include various oils known in the art, including aromatic, paraffinic, naphthenic, vegetable, and low PCA oils, such as MES, TDAE, SRAE, and heavy naphthenic oils. Suitable low PCA oils include those having a polycyclic aromatic content of less than 3 weight percent as measured by the IP346 method. The procedure for the IP346 method can be found in Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000 Parts, 2003, 62nd Edition, published by the Institute of British Petroleum (UK).

[0071] The rubber composition may contain from about 1 to about 200 phr of silica.

[0072]

[0069] Commonly used siliceous pigments that can be used in rubber compounds include conventional calcined siliceous pigments and precipitated siliceous pigments (silica). In one embodiment, precipitated silicas are used. Conventional siliceous pigments used in the present invention are, for example, precipitated silicas such as those obtained by the acidification of soluble silicates, e.g., sodium silicate.

[0073] Such conventional silicas may be characterized by having a BET surface area, as measured, for example, using nitrogen gas. In one embodiment, the BET surface area may be in the range of about 40 to about 600 square meters per gram. In another embodiment, the BET surface area may be in the range of about 80 to about 300 square meters per gram. The BET method for measuring surface area is described in Journal of the American Chemical Society, Vol. 60, p. 304 (1930).

[0074] Conventional silicas may also be characterized by having a dibutyl phthalate (DBP) absorption value in the range of about 100 to about 400, or about 150 to about 300. Conventional silicas may be expected to have an average ultimate particle size, as determined by electron microscopy, in the range of, for example, 0.01 to 0.05 microns, although silica particles may be smaller or even larger in size.

[0075]

[0072] Various commercially available silicas may be used, for example, but not limited to, silicas available from PPG Industries under the Hi-Sil trademark, model numbers 210, 243, etc., silicas available from Rhodia, e.g., Z1165MP and Z165GR, and silicas available from Degussa AG, e.g., VN2 and VN3.

[0076]

[0073] Conventional carbon blacks can be used as conventional fillers in amounts ranging from 10 to 150 phr. In another embodiment, 20 to 80 phr of carbon black can be used. Representative examples of such carbon blacks include N110, N121, N134, N220, N231, N234, N242, N293, N299, N315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990, and N991.

[0077] Other fillers may be used in the rubber composition, including, but not limited to, particulate fillers including ultra-high molecular weight polyethylene (UHMWPE), crosslinked particulate polymer gels including, but not limited to, those disclosed in U.S. Patent Nos. 6,242,534, 6,207,757, 6,133,364, 6,372,857, 5,395,891, or 6,127,488, and plasticized starch composite fillers including, but not limited to, those disclosed in U.S. Patent No. 5,672,639. Such other fillers may be used in amounts ranging from 1 to 30 phr.

[0078] In one embodiment, the rubber composition may contain a conventional sulfur-containing organosilicon compound. In one embodiment, the sulfur-containing organosilicon compound is 3,3'-bis(trimethoxy or triethoxysilylpropyl) polysulfide. In one embodiment, the sulfur-containing organosilicon compound is 3,3'-bis(triethoxysilylpropyl) disulfide and / or 3,3'-bis(triethoxysilylpropyl) tetrasulfide.

[0079] In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent No. 6,608,125. In one embodiment, the sulfur-containing organosilicon compound includes 3-(octanoylthio)-1-propyltriethoxysilane, CH3(CH2)6C(=O)-S-CH2CH2CH2Si(OCH2CH3)3, commercially available as NXT™ from Momentive Performance Materials.

[0080] In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent No. 6,849,754. In one embodiment, the sulfur-containing organosilicon compound is Si-363 manufactured by Degussa.

[0081] The amount of sulfur-containing organosilicon compound in a rubber composition will vary depending on the level of other additives used. Generally speaking, the amount of this compound ranges from 0.5 to 20 phr. In one embodiment, the amount ranges from 1 to 10 phr.

[0082] Those skilled in the art will readily understand that rubber compositions are compounded by methods commonly known in the rubber compounding art, such as by mixing various sulfur-vulcanizable constituent rubbers with various commonly used additive materials, such as sulfur donors, curing aids such as activators and retarders, and processing additives such as oils, resins including tackifying resins, and plasticizers, fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants and antiozonants, and peptizers. As known to those skilled in the art, the additives mentioned above are selected and commonly used in conventional amounts depending on the intended use of the sulfur-vulcanizable and sulfur-vulcanized material (rubber). Representative examples of sulfur donors include elemental sulfur (free sulfur), amine disulfides, polymeric polysulfides, and sulfur olefin adducts. In one embodiment, the sulfur-vulcanizing agent is elemental sulfur. The sulfur-vulcanizing agent may be used in a range of 0.5 to 8 phr, or in a range of 1.5 to 6 phr. When used, typical amounts of tackifying resins range from about 0.5 to about 10 phr, usually from about 1 to about 5 phr. Typical amounts of processing aids range from about 1 to about 50 phr. Typical amounts of antioxidants range from about 1 to about 5 phr. Representative antioxidants can be, for example, diphenyl-p-phenylenediamine and others, such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344-346. Typical amounts of antiozonants range from about 1 to 5 phr. Typical amounts of fatty acids, which may include stearic acid, when used, range from about 0.5 to about 3 phr. Typical amounts of zinc oxide range from about 2 to about 5 phr. Typical amounts of waxes range from about 1 to about 5 phr. Microcrystalline waxes are often used. Typical amounts of peptizers range from about 0.1 to about 1 phr. Typical peptizing agents can be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

[0083] Accelerators are used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanizate. In one embodiment, a single accelerator system, i.e., a primary accelerator, may be used. The primary accelerator may be used in a total amount ranging from about 0.5 to about 4 phr, or from about 0.8 to about 1.5 phr. In another embodiment, a combination of a primary accelerator and a secondary accelerator may be used to activate and improve the properties of the vulcanizate, with the secondary accelerator used in a lower amount, e.g., from about 0.05 to about 3 phr. These accelerator combinations can be expected to produce a synergistic effect on the final properties, somewhat better than the effect produced by either accelerator alone. In addition, delayed-acting accelerators may be used that are unaffected by normal processing temperatures but produce a sufficient cure at ordinary vulcanization temperatures. Vulcanization retarders may also be used. Suitable types of accelerators that may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates, and xanthates. In one embodiment, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator may be a guanidine, dithiocarbamate, or thiuram compound.

[0084] Mixing of the rubber composition can be accomplished by methods known to those skilled in the rubber mixing art. For example, the ingredients are typically mixed in at least two stages, i.e., at least one non-productive mix stage followed by a productive mix stage. The final curatives, including sulfur vulcanizing agents, are typically mixed in the final stage, conventionally referred to as the "productive" mix stage, which typically involves mixing at a lower temperature, i.e., the final temperature, than the mixing temperature of the preceding non-productive mix stage. The terms "non-productive" and "productive" mix stages are well known to those skilled in the rubber mixing art. The rubber composition may be subjected to a thermomechanical mixing step. The thermomechanical mixing step generally involves mechanical work in a mixer or extruder for a suitable period of time to produce a rubber temperature between 140°C and 190°C. The appropriate duration of the thermomechanical work varies as a function of the operating conditions and the volume and nature of the ingredients. For example, the thermomechanical work may be from 1 to 20 minutes.

[0085] The 1,4-cis polydienes, or elastomer or rubber components of the present invention can be incorporated into various articles of manufacture, such as tires and industrial rubber products, which can be prepared using such rubber compositions. Upon vulcanization, such rubber compositions can be incorporated into pneumatic or non-pneumatic tires, belts, hoses, air springs, footwear, or motor mounts. In the case of tires, the rubber compositions can be incorporated into various rubber tire components, such as treads (including tread caps and / or tread bases), sidewalls, apex, chafers, sidewalls, inserts, wire coats, and / or innerliners. In one embodiment, the compound is a tread. In yet a further embodiment, the composition can be used in adhesives.

[0086] The pneumatic tire of the present invention can be a race tire, passenger tire, aircraft tire, agricultural tire, earthmover tire, off-road tire, truck tire, etc. In one embodiment, the tire is a passenger or truck tire. The tire can also be radial or bias.

[0087]

[0084] The present invention is illustrated by the following examples which are for illustrative purposes only and should not be construed as limiting the scope of the invention or the manner in which it may be practiced. Parts and percentages are given by weight unless specifically indicated otherwise. [Example]

[0088] Experiment 1 (control) Polymerization was carried out in a 37.85 liter (10 gallon) stirred reactor set at 75°C with an initial pressure ranging between 40 psig and 50 psig. To remove impurities, the mixture was dried by circulating it through a drying bed packed with silica gel, activated alumina, and molecular sieves for approximately 16 hours. The desired amount of premix was transferred to the reactor. The reactor was charged with 13.62 kg of premix (12%, 1620 grams of 1,3-butadiene in 12,000 grams of hexane) and diisobutylaluminum hydride (DIBAH) (14 mmol). The catalyst, neodymium preform with a Nd molar concentration of 0.06 (0.085 mmphr), was injected into the reactor (approximately 23 mL) to initiate the reaction. The catalyst was obtained from Comar Chemicals Ltd. and used as received. The reactor temperature rose sharply to 81-84°C. When the reaction was complete after approximately 90 minutes, the reactor contents (cement) were transferred to a stop cylinder (a 15-gallon stirred cylinder) to which was added isopropanol (2 phm), water (50 phm), and Irganox 1520L (0.15 phm) and stirred for 0.5 hours. The batch was steam distilled and dried. The polymer yield was 1591 g (98.2% conversion). Using a Monsanto Mooney viscometer with a large rotor, a 1-minute warm-up time, and a 4-minute run time, the Mooney viscosity (ML1+4) of the polymer was determined to be 18.5 at 100°C. As measured by gel permeation chromatography (GPC), the polymer had a number-average molecular weight (Mn) of 167,800 g / mol, a weight-average molecular weight (Mw) of 267,000 g / mol, and a molecular weight distribution (Mw / Mn) of 1.6. Infrared spectroscopy analysis of the polymer showed a 1,4-cis bond content of 95.23%, a 1,4-trans bond content of 4.13%, and a 1,2-bond content of 0.64%.

[0089] Test 2: The same procedure as above was followed, except that 3,8-bis(methylene)-1,9-decadiene (3.1 mmol) was added to the premix solution. The polymer yield was 1601 g (98.9% conversion). Using a Monsanto Mooney viscometer with a large rotor, a 1-minute warm-up time, and a 4-minute run time, the Mooney viscosity (ML1+4) of the polymer was determined to be 45.9 at 100°C. As measured by gel permeation chromatography (GPC), the polymer had a number-average molecular weight (Mn) of 202,600 g / mol, a weight-average molecular weight (Mw) of 396,000 g / mol, and a molecular weight distribution (Mw / Mn) of 1.95. Infrared spectroscopy analysis of the polymer indicated a 1,4-cis content of 96.1%, a 1,4-trans content of 3.65%, and a 1,2-linkage content of 0.25%.

[0090] Test 3: The same procedure as above was followed, except that 3,8-bis(methylene)-1,9-decadiene (6.6 mmol) was added to the premix solution. The polymer yield was 1577 g (97.3% conversion). Using a Monsanto Mooney viscometer with a large rotor, a 1-minute warm-up time, and a 4-minute run time, the Mooney viscosity (ML1+4) of the polymer was determined to be 89.4 at 100°C. As measured by gel permeation chromatography (GPC), the polymer had a number-average molecular weight (Mn) of 163,800 g / mol, a weight-average molecular weight (Mw) of 365,000 g / mol, and a molecular weight distribution (Mw / Mn) of 2.23. Infrared spectroscopy analysis of the polymer showed a 1,4-cis bond content of 95.55%, a 1,4-trans bond content of 4.14%, and a 1,2-bond content of 0.31%.

[0091]

[0088] Variations in the present invention are possible in light of the description thereof provided herein. While certain representative embodiments and details have been described for the purpose of illustrating the subject invention, those skilled in the art will understand that various changes and modifications can be made without departing from the scope of the subject invention. It is therefore understood that changes can be made in the particular embodiments described that are within the full intended scope of the invention, as defined by the following appended claims.

Claims

1. polymerizing at least 1,3-butadiene monomer in the presence of a lanthanide catalyst system and a bisdiene additive; A method for synthesizing 1,4-cis polydienes, comprising:

2. Bisdiene has the formula: Diene-(CH ２ ) ｎ -Y-(CH ２ ) ｍ -Jien wherein m+n is greater than 2 and Y is sulfur or other chalcogen. The method of claim 1 , comprising:

3. Bisdiene has the formula: Diene-(CH ２ ) ｎ -X-(CH ２ ) ｍ -Jien wherein m+n is greater than 2; X is an aliphatic hydrocarbon group, a cycloaliphatic hydrocarbon, an aliphatic perfluorocarbon, or an aromatic hydrocarbon, or a combination thereof; a silane or siloxane; a phosphine or phosphine oxide; an epoxide group, an ethylene oxide group, or a propylene oxide group. The method of claim 1 , comprising:

4. The method of claim 1 , wherein the lanthanide catalyst system comprises a neodymium catalyst.

5. 5. The method of claim 4, wherein the lanthanide catalyst system is prepared by (1) reacting a neodymium carboxylate with an organoaluminum compound in the presence of a conjugated diolefin monomer to form a neodymium-aluminum catalyst component, and (2) subsequently reacting the neodymium-aluminum catalyst component with an alkylaluminum chloride to form a neodymium catalyst system, wherein the neodymium catalyst is prepared at a temperature within the range of about −60° C. to about 150° C., wherein the organoaluminum compound is selected from the group consisting of trialkylaluminum compounds and dialkylaluminum hydride compounds, and wherein the molar ratio of isoprene monomer to neodymium ranges from about 5 / 1 to about 500 / 1.

6. A 1,4-cis polydiene that is the reaction product of at least 1,3-butadiene monomer in the presence of a lanthanide catalyst system and a bis-diene additive.

7. 7. The 1,4-cis polydiene of claim 6 having a Mooney viscosity (ML1+4 at 100° C.) of about 40 to about 90.

8. 7. The 1,4-cis polydiene of claim 6, wherein the molar ratio of monomer to bisdiene ranges from 4,200 to 29,000.

9. A tire having at least a tread compound or a carcass compound containing the 1,4-cis polydiene of claim 6.

10. The 1,4-cis polydiene of claim 6, wherein the bisdiene additive is crosslinked with an aliphatic hydrocarbon group, an alicyclic hydrocarbon, an aliphatic perfluorocarbon, or an aromatic hydrocarbon, or a combination thereof.

11. The 1,4-cis polydiene of claim 6, wherein the bisdiene additive is crosslinked with sulfur, chalcogen, or a combination thereof.

12. The 1,4-cis polydiene of claim 6, wherein the bisdiene additive is crosslinked with a silane or siloxane.

13. The 1,4-cis polydiene of claim 6, wherein the bis-diene additive is crosslinked with a phosphine or phosphine oxide.

14. The 1,4-cis polydiene of claim 6, wherein the bisdiene additive is crosslinked with an epoxide.

15. The 1,4-cis polydiene of claim 6, wherein the bis-diene additive is crosslinked with ethylene oxide or propylene oxide groups.

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