JP2012097194A - Polybutadiene and method for producing the same, and rubber composition and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for selectively producing polybutadiene from a mixture of 4C unsaturated hydrocarbons.SOLUTION: The method for producing polybutadiene is characterized in that polybutadiene is synthesized from a mixture containing 1,3-butadiene and 4C unsaturated hydrocarbon other than the 1,3-butadiene in the presence of a catalyst system comprising: a rare earth element compound or its reaction product with a Lewis base (component A); an organoaluminum compound (component B) represented by general formula (II): AlRRR(wherein Rand Rare the same or different and represent a 1-10C hydrocarbon group or H, and Rrepresents a 1-10C hydrocarbon group, provided that Rmay be the same as or different from the above Ror R); at least one halogen compound (component C) selected from a Lewis acid, the complex compound of a metal halide and a Lewis base, and an active halogen-containing organic compound; and, optionally, aluminoxane (component D).

Description

  The present invention relates to polybutadiene and a method for producing the same, and a rubber composition and a tire using polybutadiene, and more particularly to a method for selectively producing polybutadiene from a mixture of unsaturated hydrocarbons having 4 carbon atoms.

Conventionally, for selectively synthesizing polybutadiene having a high cis-1,4 bond content of butadiene monomer units from a mixture containing butadiene and other unsaturated hydrocarbons having 4 carbon atoms, such as C4 fraction. In addition, various catalysts have been studied. In Japanese Patent Laid-Open No. 58-154705 (Patent Document 1), a catalyst containing a combination of a rare earth metal compound and a trialkylaluminum is used to prepare a mixture containing 1,3-butadiene and other unsaturated C ₄ hydrocarbon compounds. It is disclosed that a high-cis polybutadiene can be selectively synthesized. However, in the method using the catalyst described in Patent Document 1, high-cis polybutadiene is not obtained in a sufficient yield. Also, in Japanese translation of PCT publication No. 2006-506494 (Patent Document 2), 1,3-butadiene and four carbon atoms are prepared using a catalyst comprising a combination of a rare earth metal organophosphate, an alkylaluminum and an alkylaluminum halide. It is disclosed that high-cis polybutadiene can be selectively synthesized from one or more monoolefins having the following formula. However, in Patent Document 2, no consideration has been given to the selective polymerization of 1,3-butadiene in the presence of unsaturated hydrocarbons other than monoolefins such as 1,2-butadiene and 1-butyne. Absent. Further, in US Pat. No. 3,066,128 (Patent Document 3), a special catalyst comprising a heavy metal halide such as cobalt halide and an active species is used to selectively select a mixture of butadiene, butene and cyclic hydrocarbon. Discloses that high-cis polybutadiene can be synthesized.

JP 58-154705 A JP-T-2006-506494 U.S. Pat. No. 3,066,128

  Therefore, an object of the present invention is to provide a novel method for selectively producing polybutadiene from a mixture of unsaturated hydrocarbons having 4 carbon atoms by a specific catalyst system, and a polybutadiene obtained by the method. . Another object of the present invention is a rubber composition comprising such a polybutadiene and having excellent wear resistance, crack growth resistance, ozone deterioration resistance and workability, and at least one of the rubber compositions. It is providing the tire used for the member.

  As a result of intensive studies to achieve the above object, the present inventors polymerized a mixture containing 1,3-butadiene and other unsaturated hydrocarbons having 4 carbon atoms in the presence of a specific catalyst system. As a result, it was found that polybutadiene can be selectively synthesized, and the present invention has been completed.

That is, the method for producing the polybutadiene of the present invention comprises:
Component (A): The following general formula (I):
L ₃ M (I)
[Wherein L is R ¹ CO ₂ , R ¹ O, (R ¹ O) ₂ P (═O) O (wherein R ¹ is a hydrocarbon group having 1 to 20 carbon atoms); Is a rare earth element having an atomic number of 57 to 71 in the periodic table], or a reaction product of these compounds with a Lewis base,
Component (B): The following general formula (II):
AlR ² R ³ R ⁴ ... (II)
[Wherein, R ² and R ³ are the same or different and are a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, and R ⁴ is a hydrocarbon group having 1 to 10 carbon atoms, provided that R ⁴ represents the above May be the same as or different from R ² or R ³ ],
Component (C): at least one halogen compound selected from the group consisting of Lewis acids, complex compounds of metal halides and Lewis bases, and organic compounds containing active halogens, and as required
Synthesis of polybutadiene from a mixture containing 1,3-butadiene and one or more unsaturated hydrocarbons having 4 carbon atoms other than 1,3-butadiene in the presence of a catalyst system comprising component (D): aluminoxane. It is characterized by.

  In a preferred embodiment of the method for producing polybutadiene of the present invention, the component (A) is a neodymium branched carboxylate or a reaction product of the salt and a Lewis base.

  In another preferred embodiment of the method for producing polybutadiene of the present invention, the catalyst system comprises the component (A), the component (B), the component (C), and optionally the component (D) and a conjugated diene monomer. In the presence of

  In the method for producing polybutadiene of the present invention, the proportion of 1,3-butadiene in the mixture is preferably 20% by mass or more.

  In another preferred embodiment of the method for producing polybutadiene of the present invention, the mixture is a C4 fraction obtained by naphtha cracking.

  The method for separating polybutadiene and spent BB according to the present invention is a method for separating polybutadiene and spent BB from a C4 fraction obtained by cracking naphtha, wherein the polybutadiene is separated from the C4 fraction by the above polybutadiene production method. And then recovering the residue of the C4 fraction.

  The polybutadiene of the present invention is obtained by the above method, and the rubber composition of the present invention further includes the polybutadiene. Further, the tire of the present invention includes the rubber. The composition is used for any member of a tire.

  According to the present invention, a cis-1,4 bond content is obtained by polymerizing a mixture containing 1,3-butadiene and other unsaturated hydrocarbons having 4 carbon atoms in the presence of a specific catalyst system. High polybutadiene can be provided. The present invention also provides a rubber composition comprising such polybutadiene and having excellent wear resistance, crack growth resistance, ozone deterioration resistance and workability, and a tire using the rubber composition in at least any member. be able to. Furthermore, by using such a method for producing polybutadiene, polybutadiene and spent BB can be separated from a C4 fraction obtained by naphtha cracking.

It is the schematic of an example of the separation method of the polybutadiene and spent BB of this invention.

  Below, the manufacturing method of the polybutadiene of this invention is demonstrated in detail. The polybutadiene production method of the present invention is described in detail below in the presence of a catalyst system comprising the component (A), the component (B) and the component (C), or the component (A), the component (B), and the component (C). Synthesizing polybutadiene from a mixture containing 1,3-butadiene and one or more unsaturated hydrocarbons having 4 carbon atoms other than 1,3-butadiene in the presence of a catalyst system comprising component (D) and component (D); It is characterized by.

The component (A) of the catalyst system used in the method for producing polybutadiene of the present invention has the following general formula (I):
L ₃ M (I)
(In the formula, L is R ¹ CO ₂ , R ¹ O, (R ¹ O) ₂ P (═O) O (where R ¹ is a hydrocarbon group having 1 to 20 carbon atoms); Is a rare earth element having an atomic number of 57 to 71 in the periodic table) or a reaction product of these compounds with a Lewis base. Here, among the rare earth elements having atomic numbers 57 to 71, neodymium, praseodymium, cerium, lanthanum, gadolinium, or the like, or a mixture thereof is preferable, and neodymium is particularly preferable.

  As the compound represented by the general formula (I), a salt soluble in a hydrocarbon solvent is preferable, and specific examples thereof include carboxylates, alkoxides, and phosphates of the rare earth elements. Among these, , Carboxylates and phosphates are preferred, with carboxylates being particularly preferred. Here, examples of the hydrocarbon solvent include saturated aliphatic hydrocarbons having 4 to 10 carbon atoms such as butane, pentane, hexane and heptane, saturated alicyclic hydrocarbons having 5 to 20 carbon atoms such as cyclopentane and cyclohexane, -Monoolefins such as butene, 2-butene, aromatic hydrocarbons such as benzene, toluene, xylene, methylene chloride, chloroform, trichloroethylene, perchloroethylene, 1,2-dichloroethane, chlorobenzene, bromobenzene, chlorotoluene, etc. A halogenated hydrocarbon is mentioned.

In the rare earth element carboxylate, R ¹ may be saturated or unsaturated, preferably an alkyl group or an alkenyl group, and may be linear, branched or cyclic. Furthermore, the carboxyl group is bonded to a primary, secondary or tertiary carbon atom. As the carboxylate, specifically, octanoic acid, 2-ethylhexanoic acid, oleic acid, neodecanoic acid, stearic acid, benzoic acid, naphthenic acid, versatic acid [trade names of Shell Chemical Co., Ltd. , A carboxylic acid in which a carboxyl group is bonded to a tertiary carbon atom] and the like. Among these, salts of 2-ethylhexanoic acid, neodecanoic acid, naphthenic acid, and versatic acid are preferable. Among the carboxylates, neodymium carboxylates are more preferred, and neodymium branched carboxylates such as neodymium 2-ethylhexanoate, neodymium neodecanoate, and neodymium versatic acid salt are most preferred.

In the rare earth element alkoxide, examples of the alkoxy group represented by R ¹ O include a 2-ethyl-hexylalkoxy group, an oleylalkoxy group, a stearylalkoxy group, a phenoxy group, and a benzylalkoxy group. Among these, a 2-ethyl-hexylalkoxy group and a benzylalkoxy group are preferable.

  Examples of the rare earth element phosphate include the rare earth element, bis (2-ethylhexyl) phosphate, bis (1-methylheptyl) phosphate, bis (p-nonylphenyl) phosphate, and bis (polyethylene glycol). -P-nonylphenyl), phosphoric acid (1-methylheptyl) (2-ethylhexyl), phosphoric acid (2-ethylhexyl) (p-nonylphenyl) and the like, among these, , Bis (2-ethylhexyl) phosphate, and bis (1-methylheptyl) phosphate are preferable.

  Among the compounds represented by the general formula (I), neodymium phosphate and neodymium carboxylate are more preferable, especially neodymium 2-ethylhexanoate, neodymium neodecanoate, neodymium versatic acid. Most preferred is a branched carboxylate of neodymium such as a salt.

  Further, the component (A) may be a reaction product of a compound represented by the above general formula (I) and a Lewis base. The reaction product is improved in the solubility of the compound represented by the general formula (I) in the solvent by the Lewis base, and can be stably stored for a long period of time. The Lewis base used for easily solubilizing the compound represented by the general formula (I) in a solvent and for stable storage for a long period of time is 0 to 30 mol, preferably 1 It is used at a ratio of ˜10 mol as a mixture of the two or as a product obtained by reacting both in advance. Here, examples of the Lewis base include acetylacetone, tetrahydrofuran, pyridine, N, N-dimethylformamide, thiophene, diphenyl ether, triethylamine, an organic phosphorus compound, and a monovalent or divalent alcohol.

  The compound represented by the above general formula (I) as the component (A) described above or the reaction product of these compounds with a Lewis base may be used alone or in combination of two or more. It can also be used.

The component (B) of the catalyst system used in the method for producing polybutadiene of the present invention has the following general formula (II):
AlR ² R ³ R ⁴ ... (II)
(Wherein R ² and R ³ are the same or different and are a hydrocarbon group or hydrogen atom having 1 to 10 carbon atoms, and R ⁴ is a hydrocarbon group having 1 to 10 carbon atoms, provided that R ⁴ is And may be the same as or different from R ² or R ³ . Examples of the organoaluminum compound of the formula (II) include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-t-butylaluminum, tripentylaluminum, Trihexyl aluminum, tricyclohexyl aluminum, trioctyl aluminum; diethyl aluminum hydride, di-n-propyl aluminum hydride, di-n-butyl aluminum hydride, diisobutyl aluminum hydride, dihexyl aluminum hydride, diisohexyl hydride Aluminum, dioctyl aluminum hydride, diisooctyl aluminum hydride; ethyl aluminum dihydride, n-propyl aluminum diha Examples include idride and isobutylaluminum dihydride. Among these, triethylaluminum, triisobutylaluminum, diethylaluminum hydride, and diisobutylaluminum hydride are preferable. The organoaluminum compound as the component (B) described above can be used singly or as a mixture of two or more.

  The component (C) of the catalyst system used in the polybutadiene production method of the present invention is at least one selected from the group consisting of Lewis acids, complex compounds of metal halides and Lewis bases, and organic compounds containing active halogens. Halogen compound.

  The Lewis acid has Lewis acidity and is soluble in hydrocarbons. Specifically, methyl aluminum dibromide, methyl aluminum dichloride, ethyl aluminum dibromide, ethyl aluminum dichloride, butyl aluminum dibromide, butyl aluminum dichloride, dimethyl aluminum bromide, dimethyl aluminum chloride, diethyl bromide Aluminum, diethylaluminum chloride, dibutylaluminum bromide, dibutylaluminum chloride, methylaluminum sesquibromide, methylaluminum sesquichloride, ethylaluminum sesquibromide, ethylaluminum sesquichloride, dibutyltin dichloride, aluminum tribromide, antimony trichloride, Examples include antimony pentachloride, phosphorus trichloride, phosphorus pentachloride, tin tetrachloride, and silicon tetrachloride. Among these, diethylaluminum chloride, sesquiethylaluminum chloride, ethylaluminum dichloride, diethylaluminum bromide, ethylaluminum sesquibromide, and ethylaluminum dibromide are preferable. Alternatively, a reaction product of an alkylaluminum and a halogen such as a reaction product of triethylaluminum and bromine can be used.

  The metal halide constituting the complex compound of the above metal halide and Lewis base includes beryllium chloride, beryllium bromide, beryllium iodide, magnesium chloride, magnesium bromide, magnesium iodide, calcium chloride, calcium bromide, iodine. Calcium chloride, barium chloride, barium bromide, barium iodide, zinc chloride, zinc bromide, zinc iodide, cadmium chloride, cadmium bromide, cadmium iodide, mercury chloride, mercury bromide, mercury iodide, manganese chloride, Manganese bromide, manganese iodide, rhenium chloride, rhenium bromide, rhenium iodide, copper chloride, copper iodide, silver chloride, silver bromide, silver iodide, gold chloride, gold iodide, gold bromide, etc. Of these, magnesium chloride, calcium chloride, barium chloride, manganese chloride, zinc chloride, and copper chloride are preferred. , Magnesium chloride, manganese chloride, zinc chloride, copper chloride being particularly preferred.

  Moreover, as a Lewis base which comprises the complex compound of the said metal halide and a Lewis base, a phosphorus compound, a carbonyl compound, a nitrogen compound, an ether compound, alcohol, etc. are preferable. Specifically, tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, triethylphosphine, tributylphosphine, triphenylphosphine, diethylphosphinoethane, diphenylphosphinoethane, acetylacetone, benzoylacetone , Propionitrile acetone, valeryl acetone, ethyl acetylacetone, methyl acetoacetate, ethyl acetoacetate, phenyl acetoacetate, dimethyl malonate, diethyl malonate, diphenyl malonate, acetic acid, octanoic acid, 2-ethyl-hexanoic acid, olein Acid, stearic acid, benzoic acid, naphthenic acid, versatic acid, triethylamine, N, N-dimethylacetamide, tetrahydrofuran, diphenyl ether, 2-ethyl-hexyl alcohol, Examples include oleyl alcohol, stearyl alcohol, phenol, benzyl alcohol, 1-decanol, and lauryl alcohol. Among these, tri-2-ethylhexyl phosphate, tricresyl phosphate, acetylacetone, 2-ethylhexanoic acid, versatic acid, 2 -Ethylhexyl alcohol, 1-decanol and lauryl alcohol are preferred.

  The Lewis base is reacted at a ratio of 0.01 to 30 mol, preferably 0.5 to 10 mol, per 1 mol of the metal halide. When the reaction product with the Lewis base is used, the metal remaining in the polymer can be reduced.

  Examples of the organic compound containing the active halogen include benzyl chloride.

  In addition to the above components (A) to (C), it is preferable to use an organoaluminum oxy compound, so-called aluminoxane, as the component (D) in addition to the above components (A) to (C). Here, examples of the aluminoxane include methylaluminoxane, ethylaluminoxane, propylaluminoxane, butylaluminoxane, chloroaluminoxane and the like. By adding aluminoxane as the component (D), the molecular weight distribution becomes sharp, the activity as a catalyst is improved, and the reaction rate of 1,3-butadiene is improved.

  The amount or composition ratio of each component of the catalyst system used in the present invention is appropriately selected according to its purpose or necessity. Of these, the component (A) is preferably used in an amount of 0.00001 to 1.0 mmol, more preferably 0.0001 to 0.5 mmol, per 100 g of 1,3-butadiene. When the amount of component (A) used is less than 0.00001 mmol, the polymerization activity is low, and when it exceeds 1.0 mmol, the catalyst concentration increases and a deashing step is required. Moreover, the ratio of (A) component and (B) component is molar ratio, and (A) component: (B) component is 1: 1-1: 700, Preferably it is 1: 3-1: 500. Furthermore, the ratio of the halogen in the component (A) and the component (C) is in a molar ratio of 1: 0.1 to 1:30, preferably 1: 0.2 to 1:15, more preferably 1: 2.0 to 1: 5.0. It is. Further, the ratio of aluminum to the component (A) in the component (D) is 1: 1 to 700: 1, preferably 3: 1 to 500: 1 in terms of molar ratio. Outside the range of these catalyst amounts or component ratios, it is not preferable because it does not act as a highly active catalyst or requires a step of removing the catalyst residue. In addition to the above components (A) to (D), the polymerization reaction may be carried out in the presence of hydrogen gas for the purpose of adjusting the molecular weight of the polymer.

  As a catalyst component, in addition to the components (A), (B), (C), and (D), a small amount of a conjugated diene monomer such as 1,3-butadiene may be used. May be used at a ratio of 0 to 1000 moles per mole of the component (A). A conjugated diene monomer such as 1,3-butadiene as a catalyst component is not essential, but when used in combination, there is an advantage that the catalytic activity is further improved.

  The production of the catalyst is, for example, by dissolving the components (A) to (C) in a solvent and further reacting 1,3-butadiene as necessary. In that case, the addition order of each component is not specifically limited, You may add an aluminoxane as (D) component as needed. From the viewpoint of improving the polymerization activity and shortening the polymerization initiation induction period, it is preferable that these components are mixed in advance, reacted and aged. Here, the aging temperature is 0 to 100 ° C, preferably 20 to 80 ° C. When the temperature is less than 0 ° C, ripening is not sufficiently performed, and when the temperature exceeds 100 ° C, the catalytic activity is lowered and the molecular weight distribution is widened. The aging time is not particularly limited, and can be ripened by contacting in the line before adding to the polymerization reaction tank. Usually, 0.5 minutes or more is sufficient and stable for several days.

  The mixture used in the method for producing polybutadiene of the present invention contains 1,3-butadiene and one or more unsaturated hydrocarbons having 4 carbon atoms other than 1,3-butadiene. Here, examples of the unsaturated hydrocarbon include 1-butene, 2-butene, isobutene, 1,2-butadiene, 1-butyne, vinylacetylene, and the like. Note that the mixture may contain saturated hydrocarbons having 4 carbon atoms such as butane and isobutane, and saturated or unsaturated hydrocarbons having 3 or 5 carbon atoms such as propane and propylene. Moreover, the C4 fraction obtained by naphtha cracking (specifically steam cracking) can be used for the said mixture.

  Conventionally, when a C4 fraction from naphtha is used as a raw material for polybutadiene, it is necessary to extract a gas such as butene from the C4 fraction and to separate butadiene and spent BB contained in the C4 fraction ( (See FIG. 1). Here, the gas refers to a gas component under normal temperature (25 ° C.) and normal pressure (1013 Pa), and the spent BB means a C4 fraction other than butadiene, usually after extracting butadiene from the C4 fraction. Refers to the remaining fraction. However, according to the production method of the present invention, the C4 fraction obtained by naphtha cracking can be directly used as a raw material for polymerization. The C4 fraction obtained by naphtha cracking has, for example, the composition shown in Table 1.

  Therefore, the present inventors have found a method capable of selectively synthesizing polybutadiene from the C4 fraction and separating polybutadiene and spent BB from the C4 fraction without requiring a step of extracting butadiene from the C4 fraction. It was. The method for separating polybutadiene and spent BB of the present invention is a method for separating butadiene and spent BB from a C4 fraction obtained by cracking of naphtha, which is obtained by cracking of naphtha by the above-described method for producing polybutadiene. The polybutadiene is synthesized from the C4 fraction, and then the residue of the C4 fraction is recovered to separate the polybutadiene and the spent BB (see FIG. 1). Here, the residue of the C4 fraction means a C4 fraction remaining after synthesizing polybutadiene from the C4 fraction, which contains components contained in the spent BB and is usually recovered as a gas.

  In the method for producing polybutadiene of the present invention, the proportion of 1,3-butadiene in a mixture containing 1,3-butadiene and one or more unsaturated hydrocarbons having 4 carbon atoms other than 1,3-butadiene. Is preferably 20% by mass or more, and more preferably in the range of 40 to 99% by mass. If the 1,3-butadiene content is less than 20% by mass, the ratio of the compound other than 1,3-butadiene is too high, and the conversion of 1,3-butadiene may decrease.

  In addition, according to the production method of the present invention, polybutadiene having a high cis-1,4 bond content of the butadiene monomer unit can be obtained, and acetylene series such as 1-butyne (ethylacetylene) and vinylacetylene is added to the above mixture. When hydrocarbons are included, the selectivity of the 1,3-butadiene monomer unit to the cis-1,4 structure is improved and the cis-1,4 bond content is greatly increased. The ratio of the acetylene-based hydrocarbon in the mixture is preferably in the range of 0.01 to 1% by mass. If the content of the acetylene-based hydrocarbon is less than 0.01% by mass, the effect of improving the selectivity is lowered.

  The production of the polybutadiene is preferably performed by solution polymerization. Here, in the case of solution polymerization, an inert organic solvent is used as the polymerization solvent. Examples of the inert organic solvent include saturated aliphatic hydrocarbons having 4 to 10 carbon atoms such as butane, pentane, hexane and heptane, saturated alicyclic hydrocarbons having 5 to 20 carbon atoms such as cyclopentane and cyclohexane, and monoolefins. , Aromatic hydrocarbons such as benzene, toluene, xylene, halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene, 1,2-dichloroethane, chlorobenzene, bromobenzene, chlorotoluene It is done. Among these, a C5-C6 aliphatic hydrocarbon and alicyclic hydrocarbon are especially preferable. These solvents may be used alone or in combination of two or more.

  The production of the polybutadiene is preferably carried out at a polymerization temperature of 25 ° C. or less, more preferably from 10 to −78 ° C. When the polymerization temperature exceeds 25 ° C., the polymerization reaction cannot be sufficiently controlled, and the cis-1,4 bond content of the produced polybutadiene may be decreased, and the vinyl bond content is increased.

  The above polybutadiene may be produced either batchwise or continuously. In addition, in the production of the polybutadiene, in order not to deactivate the rare earth element-based catalyst and the polymer, mixing of a deactivating compound such as oxygen, water, carbon dioxide gas is minimized in the polymerization reaction system. Consideration is necessary.

  Next, the polybutadiene of the present invention will be described in detail. The polybutadiene of the present invention comprises 1,3-butadiene monomer units and is obtained by the above-described method. The 1,3-butadiene monomer units have a very high cis-1,4 bond content. . In the present invention, the microstructure of the 1,3-butadiene monomer unit in polybutadiene is measured by Fourier transform infrared spectroscopy (FT-IR method), which is known to have high measurement accuracy of vinyl bond content. .

から導かれるｅ、ｆ、ｇの値を用い、下記式(IV)、式(V)、式(VI)：
(シス−１,４結合含量)＝ｅ／(ｅ＋ｆ＋ｇ)×100（％） ・・・ (IV)
(トランス−１,４結合含量)＝ｆ／(ｅ＋ｆ＋ｇ)×100（％） ・・・ (V)
(ビニル結合含量)＝ｇ／(ｅ＋ｆ＋ｇ)×100（％） ・・・ (VI)
に従ってシス−１,４結合含量、トランス−１,４結合含量及びビニル結合含量を求める。なお、上記スペクトルの1130cm^-1付近の山ピーク値ａはベースラインを、967cm^-1付近の谷ピーク値ｂはトランス−１,４結合を、911cm^-1付近の谷ピーク値ｃはビニル結合を、736cm^-1付近の谷ピーク値ｄはシス−１,４結合を示す。 <Analysis method of microstructure by FT-IR>
Using the carbon disulfide of the same cell as a blank, an FT-IR transmittance spectrum of a polybutadiene carbon disulfide solution prepared to a concentration of 5 mg / mL was measured, and a peak peak value near 1130 cm ⁻¹ of the spectrum was a, 967 cm. valley peak value around ^-1 b, when the valley peak value around 911 cm ^-1 was c, and valley peak value around 736cm ^-1 and d, the following matrix equation (III):

Using the values of e, f, and g derived from the following formulas (IV), (V), and (VI):
(Cis-1,4 bond content) = e / (e + f + g) × 100 (%) (IV)
(Trans-1,4 bond content) = f / (e + f + g) × 100 (%) (V)
(Vinyl bond content) = g / (e + f + g) × 100 (%) (VI)
To determine the cis-1,4 bond content, trans-1,4 bond content and vinyl bond content. In the above spectrum, the peak value a near 1130 cm ⁻¹ is the baseline, the valley peak value b near 967 cm ⁻¹ is the trans-1,4 bond, and the valley peak value c near 911 cm ⁻¹ is the vinyl bond. The valley peak value d near 736 cm ⁻¹ indicates a cis-1,4 bond.

The polybutadiene of the present invention preferably has a cis-1,4 bond content of 95% or more, and more preferably a cis-1,4 bond content of 98.0% or more. Polybutadiene having a cis-1,4 bond content of less than 95% has insufficient stretch crystallinity and has little effect of improving the wear resistance, crack growth resistance and ozone degradation resistance of the rubber composition. The polybutadiene body has a cis-1,4 bond content and a vinyl bond content represented by the following formula (VII):
(Vinyl bond content) ≦ 0.25 × {(cis-1,4 bond content) −97} (%) (VII)
It is preferable to satisfy this relationship. In this case, the stretched crystallinity of the polybutadiene is further improved, and by adding the polybutadiene to the rubber composition, the wear resistance, crack growth resistance and ozone deterioration resistance of the rubber composition can be further improved. .

  The polybutadiene of the present invention preferably has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn), that is, a molecular weight distribution (Mw / Mn) of 1.6 to 3.5, preferably 1.6 to 2.7. More preferably. Here, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values in terms of polystyrene measured by gel permeation chromatography (GPC). When the molecular weight distribution (Mw / Mn) of the polybutadiene is less than 1.6, the workability of the rubber composition containing the polybutadiene is deteriorated, so that kneading becomes difficult and the physical properties of the rubber composition may not be sufficiently improved. On the other hand, when the molecular weight distribution of polybutadiene exceeds 3.5, although the unvulcanized viscosity of the rubber composition is improved, a decrease in rubber physical properties such as hysteresis loss is unfavorable.

  The polybutadiene of the present invention preferably has a number average molecular weight (Mn) of 100,000 to 500,000, more preferably 150,000 to 300,000. If the number average molecular weight of the polybutadiene is less than 100,000, the elastic modulus of the vulcanizate is lowered, the hysteresis loss is increased, and the wear resistance is further deteriorated, and if it exceeds 500,000, the rubber composition containing the polybutadiene is not preferable. Workability deteriorates, kneading becomes difficult, and physical properties of the rubber composition cannot be sufficiently improved.

  Next, the rubber composition of the present invention will be described in detail. The rubber composition of the present invention is characterized by containing the above-mentioned polybutadiene as a rubber component. By mix | blending the said polybutadiene with a rubber composition, the abrasion resistance of a rubber composition, crack growth resistance, and ozone degradation resistance can be improved significantly. In order to sufficiently secure the effect of improving the characteristics, the rubber component constituting the rubber composition preferably contains 10% by mass or more of the polybutadiene. In the rubber composition of the present invention, rubber components such as natural rubber (NR) and polyisoprene rubber (IR) can be used in combination with the above polybutadiene as the rubber component.

  The rubber composition of the present invention is preferably formed by blending 10 parts by mass or more of a filler with 100 parts by mass of the rubber component. By containing 10 parts by mass or more of the filler, the reinforcing property of the rubber composition is further improved. Here, examples of the filler include carbon black and silica.

  Further, the rubber composition of the present invention is preferably sulfur crosslinkable. Vulcanized rubber obtained by crosslinking a rubber composition with sulfur has sufficient strength as a tire member. The rubber composition of the present invention is suitable as a tire tread because of excellent abrasion resistance, and is also suitable as a sidewall of a tire because of excellent crack growth resistance and ozone degradation resistance. Moreover, since it is excellent in workability | operativity, kneading | mixing is easy and can express a high physical property.

  In addition to the rubber components and fillers described above, the rubber composition includes rubbers such as vulcanizing agents, vulcanization accelerators, anti-aging agents, anti-scorching agents, softening agents, zinc oxide, stearic acid, and silane coupling agents. A compounding agent usually used in the industry can be appropriately selected and blended within a range not impairing the object of the present invention. As these compounding agents, commercially available products can be suitably used. In addition, the said rubber composition can be manufactured by mix | blending the various compounding agent suitably selected as needed with the rubber component, kneading | mixing, heating, extrusion, etc.

  Next, the tire of the present invention will be described in detail. The tire of the present invention is characterized by using the rubber composition described above for any member of the tire, and is excellent in wear resistance, crack growth resistance and ozone deterioration resistance. The tire of the present invention is not particularly limited as long as the rubber composition is used for any member, and examples of the member include a tread, a sidewall and the like, and can be manufactured by a usual method.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

<Polymer Production Example 1>
(Preparation of catalyst solution A)
In a glass bottle with a rubber stopper with a volume of 100 mL that has been dried and substituted with nitrogen, 0.53 mL of a cyclohexane solution of neodymium neodecanoate (neodymium concentration: 0.56 M), a toluene solution of methylaluminoxane (MAO) [PMAO manufactured by Tosoh Finechem] Aluminum concentration: 2.74M) 9.31mL, diisobutylaluminum hydride [manufactured by Kanto Chemical Co., Ltd.] hexane solution (0.95M) 6.63mL, aging at room temperature for 2 minutes, diethyl aluminum chloride [manufactured by Kanto Chemical Co., Ltd.] hexane solution (0.98M) 1.22 mL was added and aged for 15 minutes with occasional stirring at room temperature. The neodymium concentration in the catalyst solution A thus obtained was 0.012 M (mol / L).

(Production of polymer A)
A glass bottle with a rubber stopper having a volume of about 1 L that was dried and purged with nitrogen was charged with 71.4 g of a mixture having the following composition and 283 g of dry cyclohexane, respectively, and sufficiently cooled in a 10 ° C. water bath. Next, 2.36 mL of catalyst solution A prepared as described above (11.8 mmol in terms of neodymium) was added, and polymerization was performed in a water bath at 10 ° C. for 60 minutes. Subsequently, the reaction was stopped by adding 2 mL of an isopropanol solution (NS-5 concentration: 5% by mass) of the anti-aging agent 2,2′-methylene-bis (4-ethyl-6-tert-butylphenol) (NS-5). Further, after reprecipitation in an isopropanol solution containing a small amount of NS-5, the polymer A was obtained by drying in a conventional manner.

<Polymer Production Example 2>
(Preparation of catalyst solution B)
In a glass bottle with a rubber stopper with a volume of 100 mL that has been dried and replaced with nitrogen, 0.27 mL of a neodymium neodecanoate cyclohexane solution (neodymium concentration: 0.56 M), and a toluene solution of triisobutylaluminum (aluminum concentration: 1.03 M) in sequence 4.22 mL Was added, and the mixture was aged at room temperature for 2 minutes. Then, 0.92 mL of a hexane solution (0.98M) of diethylaluminum chloride [manufactured by Kanto Chemical Co., Inc.] was added, and the mixture was aged at room temperature with occasional stirring for 15 minutes. The neodymium concentration in the catalyst solution B thus obtained was 0.012 M (mol / L).

(Production of polymer B)
71.4 g of the same mixture used in Polymer Production Example 1 and 283 g of dry cyclohexane were put into a glass bottle with a rubber stopper having a volume of about 1 L that was dried and purged with nitrogen, respectively, and sufficiently cooled in a 10 ° C. water bath. . Next, 5.32 mL (0.063 mmol in terms of neodymium) of the catalyst solution B prepared as described above was added, and polymerization was performed in a water bath at 10 ° C. for 60 minutes. Subsequently, the reaction was stopped by adding 2 mL of an isopropanol solution (NS-5 concentration: 5% by mass) of the anti-aging agent 2,2′-methylene-bis (4-ethyl-6-tert-butylphenol) (NS-5). Furthermore, after reprecipitating in an isopropanol solution containing a trace amount of NS-5, it was dried by a conventional method to obtain a polymer B.

  Table 1 shows the characteristics of the polybutadiene rubber (polymers A to B) obtained as described above. The microstructure was analyzed by the above-described FT-IR method. The number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were measured using a refractometer as a detector by GPC [manufactured by Tosoh Corporation, HLC-8020]. Shown in standard polystyrene conversion. The column is GMHXL [manufactured by Tosoh] and the eluent is tetrahydrofuran.

(Comparative example)
Except that neodymium trichloride was used in place of neodymium decanoate, the polymer was synthesized in the same manner as in Polymer Production Example 2, but the reaction rate of 1,3-butadiene in the mixture was less than 20%. Met.

Claims (9)

Component (A): The following general formula (I):
L ₃ M (I)
[Wherein L is R ¹ CO ₂ , R ¹ O, (R ¹ O) ₂ P (═O) O (wherein R ¹ is a hydrocarbon group having 1 to 20 carbon atoms); Is a rare earth element having an atomic number of 57 to 71 in the periodic table], or a reaction product of these compounds with a Lewis base,
Component (B): The following general formula (II):
AlR ² R ³ R ⁴ ... (II)
[Wherein, R ² and R ³ are the same or different and are a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, and R ⁴ is a hydrocarbon group having 1 to 10 carbon atoms, provided that R ⁴ represents the above May be the same as or different from R ² or R ³ ],
Component (C): at least one halogen compound selected from the group consisting of Lewis acids, complex compounds of metal halides and Lewis bases, and organic compounds containing active halogens, and as required
Synthesis of polybutadiene from a mixture containing 1,3-butadiene and one or more unsaturated hydrocarbons having 4 carbon atoms other than 1,3-butadiene in the presence of a catalyst system comprising component (D): aluminoxane. A process for producing polybutadiene characterized by the above.   The method for producing polybutadiene according to claim 1, wherein the component (A) is a branched carboxylate of neodymium or a reaction product of the salt and a Lewis base.   The catalyst system is preliminarily prepared in the presence of the component (A), the component (B), the component (C), and if necessary, the component (D) and a conjugated diene monomer. Item 2. A method for producing polybutadiene according to Item 1.   2. The method for producing polybutadiene according to claim 1, wherein the proportion of 1,3-butadiene in the mixture is 20% by mass or more.   The method for producing polybutadiene according to claim 1, wherein the mixture is a C4 fraction obtained by naphtha cracking. A method for separating polybutadiene and spent BB from a C4 fraction obtained by naphtha cracking,
A method for separating polybutadiene and spent BB, comprising synthesizing polybutadiene from the C4 fraction by the method for producing polybutadiene according to claim 5 and then recovering the residue of the C4 fraction.   A polybutadiene obtained by the method according to claim 1.   A rubber composition comprising the polybutadiene according to claim 7. A tire, wherein the rubber composition according to claim 8 is used for any member of the tire.

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