JPH05163310A - Method of polymerizing conjugated diene - Google Patents

Abstract

PURPOSE:To efficiently obtain a polymer which has a high cis content and a narrow mol.wt. distribution and shows excellent rubber properties by polymerizing a conjugated diene in the presence of a composite catalyst comprising specific components including a rare earth metal carboxylate. CONSTITUTION:A composite catalyst is prepared from a rare earth metal carboxylate represented by the formula (wherein Ln is a rare earth metal, R<1> to R<3> each is a 1-10C alkyl, R<4> is H or a 1-10C alkyl, and n is 1, 2, or 3) (e.g. neodymium 2,2,3,4-tetramethylpentanoate), an organoaluminum compound (e.g. trimethylaluminum), and a halogenated Lewis acid (e.g. diethylaluminum chloride). In the presence of this catalyst, a conjugated diene (e.g. butadiene) is bulk-polymerized or is solution-polymerized in a hydrocarbon solvent into a conjugated diene polymer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing conjugated diene polymers having a high 1,4-cis bond content and a narrow molecular weight distribution and exhibiting excellent rubber properties with extremely high efficiency. Is.

[0002]

2. Description of the Related Art As a method for polymerizing conjugated dienes having a high 1,4-cis bond content, many methods are already known. In particular, a butadiene polymer obtained by using a composite catalyst containing a transition metal compound such as nickel, cobalt, or titanium as a main component generally has a cis bond content of more than 90%, and the cis bond content of the butadiene polymer is low. It is industrially produced together with a butadiene polymer and widely used for various purposes.

As another method for producing a high-cis butadiene polymer, a method using a composite catalyst containing a rare earth metal compound as a main component is also known. The butadiene polymer obtained in this case is said to have a feature that it has excellent adhesiveness as compared with a high cis butadiene polymer obtained by a transition metal catalyst (Kautschuk und Gummi Kunst
stoffe, Vol. 22, p. 293, published 1969). However, the solubility of the rare earth metal compound, which is the main component of this type of composite catalyst, or the overall composite catalyst system in the polymerization solvent, etc., is not sufficient and may become heterogeneous, and its catalytic activity is insufficient. Met. Further, the obtained butadiene polymer has a wide molecular weight distribution, and therefore, the rubber performance such as elastic properties is not particularly excellent as compared with general high cis butadiene rubber.

Various attempts have already been made to improve the drawbacks of these composite catalysts containing a rare earth metal as a main component.
For example, prior to adding a polymerization catalyst to a polymerization system, a method of preliminarily reacting in the presence of a small amount of a conjugated diene to improve the activity (Japanese Patent Publication No. 47-14729), as a rare earth metal compound as a main component of a composite catalyst , A method using a rare earth metal alcoholate, and a method for improving the solubility of a composite catalyst by using a specified neodymium salt of a tertiary carboxylic acid (JP-A-54-40890).
Or Japanese Patent Laid-Open No. 55-66903) or a method using a specified neodymium salt of organic phosphoric acid as a main component (Py
oc. China-US Bilateral Symp. Polym. Chem. Phys. 19
79, 382 (published in 1982), etc., but the catalytic activity, especially at relatively high temperatures, is not always sufficient for industrial production, and further improvement has been desired. ..

As one of the measures to solve these problems, by using a composite catalyst containing a reaction product of a rare earth metal salt of carboxylic acid and a Lewis base such as alcohol or acetylacetone as a main component, polymerization with a hydrocarbon solvent is performed. A method for improving the solubility of the catalyst and achieving a high polymerization catalyst activity is also disclosed (JP-A-58-1709).

However, the incorporation of polar organic compounds such as alcohols and ketones into the polymerization solvent may lead to an increase in the required amount of organometals such as organoaluminum, especially in the relatively high polymerization temperature range. In addition, the resulting polymer has a non-uniform molecular weight, that is, a wide molecular weight distribution, which is not preferable for some purposes. Also,
It is known within the scope of the prior art that special operations such as pre-reactions or catalyst aging can also be used in order to achieve particularly high catalytic activities. However, the operations such as the preliminary reaction and the aging of the catalyst complicate the production process industrially, which causes problems such as a decrease in production efficiency and an increase in production cost.

[0007]

As described above, a conjugated catalyst having a high cis content can be produced by a composite catalyst containing a rare earth metal compound as a main component, particularly a composite catalyst containing a rare earth metal salt compound of a carboxylic acid as a main component. It is already known that However, it has been desired to further improve the polymerization catalytic activity, particularly the catalytic activity at relatively high temperatures.

[0008]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventor has found that a composite catalyst using a rare earth metal salt compound of a carboxylic acid having a specific structure is subjected to a preliminary reaction or catalyst aging. It is possible to achieve high catalytic activity, especially extremely high catalytic activity at relatively high temperatures, without the need for special operations, and the resulting polymers have a high cis content and excellent molecular weight distribution uniformity. The present invention has been found to have a narrow molecular weight distribution.

[0009] Among the conventionally known conjugated gen polymerization methods using a rare earth metal salt of a carboxylic acid, a rare earth metal salt of a primary carboxylic acid cannot achieve high solubility in an organic solvent. Even with a rare earth metal salt of a secondary carboxylic acid, high solubility in an organic solvent cannot be sufficiently achieved. Therefore, the polymerization activity of the composite catalyst using the rare earth metal salts of both types of carboxylic acid is generally low, and the molecular weight distribution of the obtained polymer is wide, which is not preferable. The rare earth metal salt of a tertiary carboxylic acid achieves high solubility in an organic solvent, and some improvement in the polymerization catalytic activity of the composite catalyst is recognized. However, the catalytic activity, particularly the catalytic activity at a relatively high temperature, is not always sufficient for industrially producing the conjugated gen polymers, and further improvement has been required.

The high catalytic activity of the composite catalyst used in the present invention, particularly the extremely high catalytic activity at relatively high temperatures, limits the carboxylic acid group which is a ligand of the rare earth metal salt to the scope of the claims of the present invention. As described above, it is achieved only by using a specific structure. That is, by limiting the alkyl group of the carboxylic acid compound to a multi-branched structure in a specific range, a high catalytic activity, particularly an extremely high catalytic activity at high temperature, is achieved, and in general, a polymer obtained by polymerization at high temperature is Despite the broadening of the molecular weight distribution,
In the present technology, the surprising effect that the homogeneity of the molecular weight distribution is maintained was found, and the present invention was achieved.

Regarding the method for polymerizing conjugated gens using a carboxylic acid salt of a rare earth metal, JP-A-54-40890 and JP-A-55-66903 describe the use of tertiary carboxylic acids. That is, the use of a carboxylic acid having a tertiary carbon atom at the α-position to the carbonyl group has been known. However, conventionally, all of the alkyl groups bonded to the carbon atom at the α-position have been disclosed only in a straight chain, and the idea of further branching the alkyl group, especially the carbon at the β-position is tertiary or quaternary. The way of thinking has never been done before.

That is, according to the present invention, as described in claim 1,
(A) a rare earth metal salt of a carboxylic acid represented by the following chemical formula 2,

[0013]

[Chemical 2]

Conjugated dienes characterized by subjecting conjugated dienes to bulk polymerization or solution polymerization in a hydrocarbon solvent in the presence of a composite catalyst comprising (b) an organoaluminum compound and (c) a halogen-containing Lewis acid compound. The present invention relates to a polymerization method of. Here, Ln in the general formula and the chemical formula 2 showing the composite catalyst component (a) is a rare earth metal element, R ¹ , R ² and R ³ represent an alkyl group having 1 to 10 carbon atoms, and R ⁴ is hydrogen or 1 to 1 carbon atoms
The rare earth metal element constituting the composite catalyst component (a), which is an alkyl group having 10 and n is an integer of 1, 2 or 3, is an element having an atomic number of 57 to 71, preferably an atomic number of 57. Of the 60 elements, the most preferred metal is neodymium. The rare earth metals that can be used may be a mixture of rare earth metals with each other or may contain a small amount of another metal.

The carboxylic acid constituting the composite catalyst component (a) has a tertiary or quaternary β-position relative to the carbonyl group.
Having 1, 2 or 3 primary carbon atoms, that is, n in the chemical formula 2 is 1, 2 or 3, and the carbon atom at the α-position to the carbonyl group is tertiary carbon atom. Unless it is an acid, the excellent effect of the present invention, that is, the high catalytic activity, particularly the extremely high catalytic activity at high temperature, and the effect that the polymer obtained has excellent uniformity in molecular weight distribution cannot be achieved.

The carboxylic acid constituting the composite catalyst component (a) used in the present invention includes various organic acids not particularly specified in the present invention, carboxylic acids other than those specified in the present invention, organic phosphoric acid and sulfone. An acid, phenol, etc. may be contained as impurities. However, even in this case, the effect of the present invention cannot be sufficiently achieved unless the hyperbranched carboxylic acid specified in the present invention is contained in an amount of at least 50 mol%, preferably 70%, particularly preferably 90% or more.

The hyperbranched carboxylic acid used in the present invention is, for example, a so-called Koch, which is obtained by reacting a polyolefin mixture containing an isobutylene unit in a proportion of 60% by weight or more with carbon monoxide and water in the presence of a catalyst. It can be produced by reaction. As an example of a specific method for producing the carboxylic acid, JP-A-62-164645 can be cited.

Specific examples of the carboxylic acid which constitutes the catalyst component (a) of the conjugated gen polymerization method of the present invention include:
2,3,4-tetramethylpentanoic acid, 2-ethyl-
2,3,3-trimethylbutanoic acid and the like can be mentioned. Specific examples of preferred industrial products include Equacid 9 and Equacid 13 (multibranched saturated tertiary fatty acids mainly having 9 and 13 carbon atoms, trade names of Idemitsu Petrochemical Co., Ltd.). Of course, a mixture of two or more of these may be used.

These rare earth metal salts of carboxylic acids can be easily obtained, for example, by reacting the corresponding sodium salts of carboxylic acids with chlorides of rare earth metals in a solvent such as water, alcohol or acetone. .. The organoaluminum compound which is the component (b) constituting the composite catalyst of the present invention is represented by the following formula.

AlR ⁵ _{3 -m} H _m wherein R ⁵ is an aliphatic hydrocarbon group, alicyclic hydrocarbon group having 1 to 20 carbon atoms, preferably 2 to 8 carbon atoms, or 6 to 20 carbon atoms, preferably Represents an alkyl-substituted aromatic hydrocarbon group in the range of 6 to 12. m is 0, 1 or 2, preferably 0 or 1, and H represents a hydrogen atom.

Specific examples of preferable organic aluminum compounds include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trihexylaluminum, tricyclohexylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, ethylaluminum dihydride, isobutylaluminum. Examples thereof include dihydride and the like, and particularly preferable examples include triethylaluminum, triisobutylaluminum, diethylaluminum hydride, and diisobutylaluminum hydride. Also, a mixture of two or more of these may be used.

The halogen-containing Lewis acid compound which is the component (c) constituting the composite catalyst of the present invention is III in the periodic table.
Examples thereof include halides or organometallic halides of elements belonging to b, IVb or Vb, preferably aluminum element, and as the halide, chlorine or bromine is preferable. Examples of these compounds, 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 aluminum bromide, diethyl aluminum chloride, dibutyl aluminum bromide.

Dibutylaluminum chloride, methylaluminum sesquibromide, methylaluminum sesquibromide, ethylaluminum sesquibromide, ethylaluminum sesquichloride, dibutyltin dichloride, aluminum tribromide, antimony trichloride, antimony pentachloride, phosphorus trichloride, phosphorus pentachloride. And tin tetrachloride, and particularly preferable examples thereof include diethyl aluminum chloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, diethyl aluminum bromide, ethyl aluminum sesquibromide and ethyl aluminum dibromide.

The amount or composition ratio of each component of the composite catalyst used in the production method of the present invention varies depending on its purpose. Generally, conjugated diene monomer 100g
Therefore, the amount of component (a) used is 0.01 to 5 mmol, preferably 0.05 to 1 mmol. Generally, the amount of component (b) used is 0.1-5.
It can be used in an amount of 0 mmol, preferably 0.5 to 10 mmol. Further, the molar amount of the component (c) used varies depending on the number of halogen atoms contained in the molecule, and is represented by the number of halogen atoms per 1 mol of the component (a), generally halogen atom / (a) = 1 to 6, It can be preferably used in the range of 2 to 4 atoms / mole ratio.

The monomer that can be used in the production method of the present invention can be selected from conjugated diene compounds having a carbon number of 4 to 8 such as butadiene, isoprene, piperylene, and dimethylbutadiene, or a mixture thereof. The preferred monomer is butadiene. It is also possible to polymerize or copolymerize with a vinyl aromatic compound in the presence of a vinyl aromatic hydrocarbon compound such as styrene.

The production method of the present invention is carried out by a bulk polymerization method or a solution polymerization method. Examples of the polymerization solvent that can be used when the solution polymerization method is used include n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene, and other aliphatic hydrocarbons having a boiling point of 200 ° C. or less, alicyclic hydrocarbons, or Aromatic hydrocarbons are preferred. The polymerization solvent may of course be a mixture of these two components. It is also possible to contain a small amount of halogenated hydrocarbons such as methylene chloride and chlorobenzene and aprotic polar organic solvents such as ketone compounds, ether compounds and trialkylamine compounds, and depending on the conditions, polymerization of the composite catalyst is possible. The solubility in a solvent and thus the polymerization catalyst activity can be further improved.

The polymerization temperature in the production method of the present invention is −
It is carried out at 30 to 150 ° C, preferably 10 to 130 ° C, particularly preferably 30 to 120 ° C. The polymerization reaction type can be used in either a batch method or a continuous method. It is also possible in the production method of the present invention to carry out a preliminary reaction or aging of some or all of the catalyst components in the presence or absence of the conjugated diene monomer prior to the polymerization.

In the production method of the present invention, after the polymerization reaction reaches a predetermined polymerization rate, if necessary, a known terminal modifier or terminal branching agent, a polymerization terminator, and a polymer stabilizer are added to the reaction system. In addition, the polymer can be recovered by known solvent removal and drying operations in the production of conjugated diene polymers, such as steam stripping drying and heat drying. The terminal modifier can be selected from various terminal modifiers known in the anionic polymerization technology of conjugated dienes. A specific example is
For example, it can be known from the following publicly known materials.

JP 62-149708 A JP 62-156104 A JP 62-161844 A JP 63-003041 A JP 62-022852 A terminal branching agent is also generally used. It can be selected from terminal branching agents known in the art of anionic polymerization of conjugated dienes. Examples of this are multiepoxides, multiisocyanates,
Mention may be made of multiimines, multialdehydes, multiketones, multianhydrides, multiesters, monoesters, multihalides, carbon monoxide and carbon dioxide. Particularly preferred coupling agents are multihalogenated silicon compounds such as tetrachlorosilane, trichloromonomethylsilane, trichloromonoethylsilane, and dichlorodiethylsilane, and multihalogenated tin compounds such as tetrachlorotin, trichloromonomethyltin and trichloromonoethyltin. Ester compounds such as diethyl carbonate, diphenyl carbonate, and diethyl adipate.

The amount of the coupling agent used is considered to be the optimum amount for maximum branching, so that the amount is equivalent to the used organic metal. However, depending on the desired degree of coupling,
Any amount of coupling agent can be used. Generally, the amount of coupling agent is 0.1 to 1.5 equivalents per organoaluminum. The coupling agent can be added alone or as an inert hydrocarbon solution. Further, the coupling agent can be added at once, dividedly or continuously. Although the coupling reaction varies depending on its reactivity, it is usually carried out at a temperature close to the polymerization temperature for a few minutes to a few hours.

The polymerization terminator can be selected from water or a protic polar organic compound. Examples of the latter include various alcohols, phenols and carboxylic acid compounds. The polymer stabilizer can be selected from known stabilizers for conjugated diene polymers and antioxidants. Particularly preferred examples of these are 2,6-di-tert-
Butyl-4-methylphenol, trinonylphenyl phosphate, phenyl-β-naphthylamine, N, N′-dialkyldiphenylamine, N-alkyldiphenylamine and the like can be mentioned.

The present invention provides a method for producing a conjugated gen polymer having a high cis-1,4-bond content and a narrow molecular weight distribution and exhibiting excellent rubber properties with extremely high efficiency. The resulting polymer is used for various applications that make use of its excellent rubber properties, for example, if necessary mixed with other synthetic rubber or natural rubber, and used for various parts of the tire such as tread, carcass, sidewalls, beads, or hoses. , Industrial use such as window frames, belts, anti-vibration rubber, raw rubber for automobile parts, and impact-resistant polystyrene,
By using it as a resin-reinforced rubber such as ABS resin, excellent performance and effect can be achieved.

[0033]

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0034]

[Example 1 and Comparative Examples 1 to 3] The inside of a sufficiently dried 10 liter pressure-resistant autoclave was sufficiently replaced with dry nitrogen and used for polymerization. In Example 1, 6 kg of a cyclohexane mixed solution containing 900 g of 1,3-butadiene was pressed into an autoclave, and then Equacid 13 (a multi-branched carboxylic acid having an average carbon number of 13 from Idemitsu Petrochemical Co., Ltd.) was used. A neodymium salt of a compound structure represented by the formula:
0.277 mmol, diisobutylaluminum hydride 4.44 mmol and ethylaluminum sesquichloride were added so as to have a Cl / Nd = 3 elemental ratio, and polymerization was carried out while adiabatically raising the temperature at a starting temperature of 40 ° C. for 1 hour. Including the comparative examples shown below, the maximum polymerization temperature was 10
5 to 115 ° C was reached. After polymerization, 10 wt% of BHT [2,6-bis (tert-butyl) -4-methylphenol]
After the reaction was stopped with 10 ml of a methanol / cyclohexane mixed solution of, the solvent was removed by heating to obtain a polymer.

Comparative Examples 1 to 3 are neodymium stearate,
A neodymium salt of neodymium 2-ethylhexanoate or versatic acid (Versatic acid 10: a trade name of Shell Chemistry, which is a tertiary carboxylic acid mixture having an average carbon number of 10, the chemical structure of which is shown in Chemical Formula 4). It is the result of using. These are primary carboxylic acid, secondary carboxylic acid and tertiary carboxylic acid, respectively, and all of the alkyl groups bonded to the β-position carbon are substantially linear.

[0036]

[Chemical 3]

The combination of each alkyl group is as follows: R ⁶ = CH ₃ , R ⁷ = iso-C ₃ H ₇ , R ⁸ = branched structure C ₇
H ₁₅ R ⁶ = CH ₃ , R ⁷ = tert-C ₄ H ₉ , R ⁸ = C _{6 of} branched structure
H ₁₃ R ⁶ = CH ₃ , R ⁷ = R ⁸ = neo-C ₅ H ₁₁ A mixture containing carboxylic acid as a main component.

[0038]

[Chemical 4]

At least one of the alkyl groups of R ^{9 to} R ¹¹ is a methyl group, and all the alkyl groups are basically linear structures. It is a mixture of saturated fatty acids having an average carbon number of 10 as the whole carboxylic acid. The yield of the polymer thus obtained, 1,4-cis content, molecular weight distribution and Mooney viscosity are shown in Table 1. (3) Analytical method 1) The 1,4-cis content was measured using an infrared spectrophotometer,
It was obtained by data processing by the Morello method.

2) The molecular weight distribution was measured by gel permeation chromatography using THF (tetrahydrofuran) as a developing solvent.

[0041]

Example 2 In Example 2, the neodymium salt of Equacid 13 was replaced with Equacid 9 (a multi-branched carboxylic acid mixture having an average carbon number of 9 from Idemitsu Petrochemical Co., Ltd. 0.277 mmol of neodymium salt and 4.44 mmol of diisobutylaluminum in the presence of a small amount of butadiene monomer in advance in a nitrogen atmosphere.
Mix in a glass bottle, pre-react for 10 minutes, and add ethylaluminum sesquichloride to Cl / Nd =
It was added so as to have a three-element ratio and aged for 1 hour. Polymerization was performed while adiabatically raising the temperature at a starting temperature of 30 ° C. for 2 hours. The maximum temperature of polymerization reached 110 ° C. The other conditions were the same as in Example 1. The results are shown in Table 2.
Shown in.

[0042]

[Chemical 5]

The combination of each alkyl group is represented by R ¹² = CH ₃ , R ¹³ = R ¹⁴ = iso-C ₃ H ₇ R ¹² = CH ₃ , R ¹³ = C ₂ H ₅ , R ¹⁴ = tert-C ₄ H ₉ R ¹² = R ¹³ = CH ₃ , R ¹⁴ = neo-C ₅ H ₁₁ A mixture containing carboxylic acid as a main component.

[0044]

Examples 3 to 5 Examples 3 to 5 were carried out in the same manner as Example 1 except that the organoaluminum shown in Table 3 was used instead of diisobutylaluminum hydride. The results are shown in Table 3.

[0045]

Examples 9 to 11 Examples 9 to 11 are the same as Example 1 except that the halogen-containing Lewis acid shown in Table 4 was used in place of ethylaluminum sesquichloride so as to have a Cl / Nd = 3 element ratio. It carried out similarly. The results are shown in Table 4.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

INDUSTRIAL APPLICABILITY The polymerization method of the present invention shows a high catalytic activity, particularly an extremely high catalytic activity at high temperature, without requiring special operations such as pre-reaction or catalyst aging, and the conjugated gens are extremely efficiently. Can be polymerized. In addition, in general, although the molecular weight distribution of the polymer obtained by the polymerization at high temperature expands, the present technology maintains the uniformity of the molecular weight distribution. The polymer obtained has a high cis content and a narrow molecular weight distribution and exhibits excellent rubber properties.

Claims (2)

[Claims] 1. A rare earth metal salt of a carboxylic acid represented by the following formula (1): A method for polymerizing conjugated dienes, which comprises bulk polymerizing or solution polymerizing conjugated dienes in a hydrocarbon solvent in the presence of a composite catalyst comprising (b) an organoaluminum compound and (c) a halogen-containing Lewis acid compound. .. Here, Ln in the general formula showing the composite catalyst component (a), Formula 1 is a rare earth metal element, R ¹ , R ² and R ³ represent an alkyl group having 1 to 10 carbon atoms, and R ⁴ is hydrogen or 1 to 1 carbon atoms
It is an alkyl group having 10 and n represents an integer of 1, 2 or 3. 2. The amount of the composite catalyst component (a) used is 0.01 to 0.5 millimole, the amount of the component (b) is 0.1 to 50 millimole, and the component (c) to 100 g of the conjugated diene monomer. 2. The method for polymerizing conjugated dienes according to claim 1, wherein the amount of () is represented by the amount of halogen element with respect to the component (a), and is in the range of halogen / (a) = 1 to 6 atoms / mole ratio.