JP3211274B2 - Method for producing conjugated diene polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for polymerizing a conjugated diene with a rare earth element catalyst, and then adding a coupling agent selected from a carboxylic acid ester compound and a carbonic acid ester compound to the obtained polymer solution to cause a reaction. The present invention relates to a method for producing a novel conjugated diene polymer, characterized in that the molecular weight of the polymer is increased or the polymer chain is branched.

[0002]

2. Description of the Related Art Numerous processes have been known for producing conjugated diene polymers having a high 1,4-cis bond content. 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 has a low cis bond content due to a lithium-based catalyst. It is industrially produced with butadiene polymers and is widely used for various rubber applications.

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 tackiness as compared with a high cis-butadiene polymer obtained by a transition metal catalyst (Kautschukun).
d Gummi kunst stoffe, 22nd
Volume, p. 293, published in 1969).

However, the solubility of the rare earth metal compound, which is the main component of this type of composite catalyst, or the entirety of these composite catalysts in the polymerization solvent is not sufficient, and may be non-uniform, resulting in insufficient catalytic activity. Was something. In addition, the molecular weight distribution of the resulting butadiene polymer becomes broad,
Therefore, rubber performance such as elasticity was not particularly excellent as compared with general high cis-butadiene rubber.

Various attempts have already been made to improve the drawbacks of these rare earth metal-based composite catalysts.
For example, prior to addition of a polymerization catalyst to a polymerization system, a method of pre-reacting in the presence of a small amount of a conjugated diene to improve the activity (Japanese Patent Publication No. 47-14729), a rare earth metal compound which is a main component of a composite catalyst Examples of the method include a method using an alcoholate of a rare earth metal and a method using a specified neodymium salt of a tertiary carboxylic acid to improve the solubility of a composite catalyst (JP-A-54-40890, JP-A-55-66903). ) Or a method using a specified neodymium salt of an organic phosphoric acid as a main component (Pyoc. China-US)
Bilateral Symp. Polym. Che
m. phys. 1979, 382 (published in 1982)) and the like. According to these improved catalyst technologies, a high cis-butadiene polymer having a relatively narrow molecular weight distribution can be obtained with high activity, and the polymer is said to have excellent physical performance.

[0006]

As described above, it is already known that a conjugated diene polymer having a high cis content can be obtained by a composite catalyst containing a rare earth metal compound as a main component. However, since the obtained polymer is generally a linear polymer having a small number of branched structures, it has excellent basic performance as a rubber material such as strength performance and elastic performance as compared with a conventional high cis conjugated diene polymer, Depending on the application, there is a problem in mixing properties with other polymer materials such as rubber, various fillers, etc. or processing operability. In particular, in the use as a resin modifier such as HIPS (rubber reinforced high impact polystyrene), the solution viscosity of the styrene solution of the linear rubber at the time of production becomes extremely high, so that the target HI
Although depending on the PS characteristics and the HIPS manufacturing method, generally, the demand for reducing the solution viscosity by introducing a branched structure was extremely strong.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, polymerized a conjugated diene with a rare earth element-based catalyst and then reacted with a carboxylic acid ester compound or a carbonic acid ester compound. As a result, the polymer molecular weight can be increased or the polymer chain can be branched, and the polymer obtained thereby can solve the above-mentioned problems while maintaining the excellent properties as a rubber material. The invention has been reached.

By the way, although the techniques are completely different, various kinds of terminal coupling agents are known in the art of anionic polymerization of conjugated dienes. Examples of coupling agents include multi-epoxide, multi-isocyanate, multi-imine,
Examples include compounds such as multialdehyde, multiketone, various carboxylic esters, multiacid anhydrides, multihalides, carbon monoxide, and carbon dioxide.

However, as a result of intensive studies by the present inventors, in the polymerization using a composite catalyst containing a rare earth element as a main component, the coupling efficiency when these coupling agents are used is affected by the reaction conditions. Surprisingly, when a carboxylic acid ester compound or a carbonic acid ester compound is used as a coupling agent, the effect of increasing the molecular weight of the polymer is extremely high. The inventors have found that a chain branching effect can be achieved, and have reached the present invention.

That is, the present invention relates to (a) general formula LnY ₃ (formula
Where Ln is a rare earth element and Y is an acid residue)
Organic compounds of rare earth elements to be, (b) an organoaluminum compound and (c), the periodic table IIIb, IVb or Vb
Condensed dienes are subjected to bulk polymerization or solution polymerization in a hydrocarbon solvent in the presence of a composite catalyst comprising a halogen-containing Lewis acid compound selected from halides of elements belonging to the following, and then an ester compound of carboxylic acid and alcohol or phenol and carbonic acid A method for producing a novel conjugated diene-based polymer, characterized by adding and reacting a coupling agent selected from ester compounds of phenol and alcohol or phenol. The ester compound of a carboxylic acid and an alcohol or a phenol as a coupling agent is preferably defined by the following general formula (1).

[0011]

Embedded image Here, R ¹ has a carbon number in the range of 1 to 10,000, more preferably 1 to 1,000, and particularly preferably 1 to 1,000.
There are in the range of 100 aliphatic, cycloaliphatic or aromatic hydrocarbon groups. R ² is an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 50 carbon atoms, particularly preferably 1 to 20 carbon atoms. n is an integer in the range of 1 to 5,000, more preferably in the range of 1 to 500, and particularly preferably in the range of 1 to 10. By selecting the number n, the functional number of the coupling agent, and thus the number of branches of the obtained conjugated diene polymer can be freely adjusted.

Preferred specific examples include ethyl acetate, butyl stearate, diethyl adipate, diethyl maleate, methyl benzoate, ethyl acrylate, methyl methacrylate, diethyl phthalate, diethyl isophthalate, diethyl terephthalate, and trimellitate. Examples thereof include tributyl acid, tetraoctyl pyromellitate, hexaethyl melitate, phenyl acetate, polymethyl methacrylate, polyethyl acrylate, and polyisobutyl acrylate. The other coupling agent, an ester compound of carbonic acid and alcohol or phenol, is preferably defined by the following general formula (2).

[0013]

Embedded image Here, R ³ and R ⁴ are an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 50 carbon atoms, particularly preferably an aliphatic or alicyclic group having 1 to 20 carbon atoms. Or it is an aromatic hydrocarbon group.

Preferred examples include dimethyl carbonate,
Examples thereof include diethyl carbonate, dipropyl carbonate, dihexyl carbonate, dicyclohexyl carbonate, and diphenyl carbonate. Further, as long as the object of the present invention is not impaired, the coupling agent molecule may contain an aprotic polar group such as an ether group or a tertiary amino group. The coupling agent may be a mixture of two or more of these compounds. Furthermore, a compound containing a free carboxylic acid group, an alcohol group, or a phenol group may be contained as an impurity within a range not to impair the object of the present invention.

The rare earth element compound as the component (a) constituting the composite catalyst used in the method for producing a conjugated diene polymer of the present invention has the formula

[0016]

Embedded image It is represented by LnY ₃ . Here, Ln is a rare earth element. Specifically, scandium, yttrium or an atomic number of 57 to
It is a lanthanide series rare earth element of the periodic table No. 71. Among them, lanthanum, cerium, praseodymium, neodymium and gadolinium are preferred, and neodymium is particularly preferred in view of the balance between performance and industrial availability. Also,
These rare earth elements may be a mixture of two or more kinds. Y represents an acid residue. Preferred examples include salts of alcohols, phenols, thioalcohols, thiophenols, amines, carboxylic acids, organic phosphoric acids, and organic phosphorous acids.

The alcohol type compounds (alkoxides and phenoxides) are represented by the general formula

[0018]

Embedded image R ⁵ is preferably an alkyl group having 1 to 40 carbon atoms, an alkenyl group, an alkyl- or alkenyl-substituted phenyl group or an alkyl- or alkenyl-substituted naphthyl group. The alkyl or alkenyl group may be linear, branched or cyclic. Specific examples of preferred alcohols and phenols include 2-ethyl-hexyl alcohol, oleyl alcohol, stearyl alcohol, nonylphenol, benzene alcohol and the like.

The thioalcohol type compound (thioalkoxide, thiophenoxide) is represented by the general formula

[0020]

Embedded image R ⁶ is preferably an alkyl group having 1 to 40 carbon atoms, an alkenyl group, an alkyl- or alkenyl-substituted phenyl group or an alkyl- or alkenyl-substituted naphthyl group. The alkyl or alkenyl group may be linear, branched or cyclic.

The amine compound of the rare earth metal is represented by the general formula

[0022]

Embedded image Wherein R ⁷ is preferably an alkyl group having 1 to 40 carbon atoms, an alkenyl group, an alkyl or alkenyl substituted phenyl group or an alkyl or alkenyl substituted naphthyl group. The alkyl or alkenyl group may be linear, branched or cyclic.

As the carboxylic acid compound of the rare earth element,
General formula

[0024]

Embedded image R ⁸ is preferably an alkyl group, alkenyl group, alkyl- or alkenyl-substituted phenyl group or alkyl- or alkenyl-substituted naphthyl group in the range of 1 to 40. An alkyl or alkenyl group is linear,
It may be branched or annular. The carboxyl group may be a primary, secondary or tertiary bond to a hydrocarbon. Specific examples of preferred carboxylic acids include octanoic acid, 2-ethyl-hexanoic acid, oleic acid, stearic acid, benzoic acid, naphthenic acid, and versatic acid 10 (trade name of Shell Chemical).

The organic phosphate compound of the rare earth element includes
General formula

[0026]

Embedded image Wherein R ⁹ and R ¹⁰ are the same or different and are preferably an alkyl group in the range of 1 to 40, an alkenyl group, an alkyl or alkenyl substituted phenyl group or an alkyl or alkenyl substituted naphthyl group. In particular, the alkyl or alkenyl group may be linear, branched or cyclic. As specific examples of preferred organic phosphoric acid compounds,
Tris (di-2-ethylhexyl phosphate) and tris (dinonylphenyl phosphate) are exemplified.

The rare earth element organic phosphite compound is represented by the general formula

[0028]

Embedded image R ¹¹ and R ¹² are the same or different and are preferably 1 to 40 alkyl groups, alkenyl groups, alkyl or alkenyl substituted phenyl groups or alkyl or alkenyl substituted naphthyl groups. The alkyl or alkenyl group may be linear, branched or cyclic. Specific examples of preferred organic phosphite compounds include tris (di-2-ethylhexyl phosphite) and tris (dinonylphenyl phosphite).

The organoaluminum compound as component (b) constituting the composite catalyst used in the method for producing a conjugated diene polymer of the present invention has the formula

[0030]

Embedded image It is represented by Here, R ¹³ is an aliphatic or alicyclic hydrocarbon group having 1 to 20, preferably 2 to 8 carbon atoms, or an alkyl or alkenyl group having 6 to 20, preferably 6 to 12 carbon atoms. Represents a substituted aromatic hydrocarbon group. l is 0, 1 or 2, preferably 0 or 1, and H represents a hydrogen atom.

Specific examples of preferred organoaluminum compounds include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trihexylaluminum, tricyclohexylaluminum, diethylaluminum dihydride, diisobutylaluminum hydride, ethylaluminum dihydride, isobutyl Examples include aluminum dihydride, and particularly preferred examples include triethylaluminum, triisobutylaluminum, diethylaluminum hydride, and diisobutylaluminum hydride. Further, a mixture of two or more of these may be used.

The Lewis acid compound containing a halogen element as the component (c) constituting the composite catalyst used in the method for producing a conjugated diene polymer of the present invention is represented by IIIb or IV in the periodic table.
A halogen compound of an element belonging to b or Vb, preferably, a halide of an aluminum element or an organic metal halide is used. As the halogen element, chlorine or bromine is preferable.

Examples of these compounds include methyl aluminum dibromide, methyl aluminum dichloride, ethyl aluminum dibromide, ethyl aluminum dichloride, butyl aluminum dibromide,
Butylaluminum dichloride, dimethylaluminum bromide, dimethylaluminum chloride, diethylaluminum bromide, diethylaluminum chloride, dibutylaluminum bromide, dibutylaluminum chloride, methylaluminum sesquibromide, methylaluminum sesquichloride, ethylaluminum sesquibromide, ethylaluminum sesquichloride, dibutyltin There are dichloride, aluminum tribromide, antimony trichloride, antimony pentachloride, phosphorus trichloride, phosphorus pentachloride and tin tetrachloride,
Particularly preferred examples include diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum bromide, ethylaluminum sesquibromide and ethylaluminum 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 the purpose. The amount of component (a) used is generally 0.01 to 5 mmol, preferably 0.05 to 1 mmol, per 100 g of the conjugated diene monomer. Generally, the amount of component (b) used is 0.1
It can be used in the range of .about.50 mmol, preferably 0.5.about.10 mmol. Further, the molar amount used of the component (c) differs 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 rare earth element (Ln). Generally, halogen atom / Ln = 1 to 6, preferably Can be used in the range of 2 to 4.

The monomers which can be used in the production method of the present invention are generally those having 4 to 8 carbon atoms such as butadiene, isoprene, piperylene and dimethylbutadiene.
And the most 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 bulk polymerization or solution polymerization. Examples of the polymerization solvent that can be used when the solution polymerization method is used include aliphatic hydrocarbons having a boiling point of 200 ° C. or less, such as n-pentane, n-hexane, n-heptane, cyclohexane, benzene, and toluene, and alicyclic hydrocarbons. Hydrogen or aromatic hydrocarbons are preferred. The polymerization solvent may of course be a mixture of these two components. It is also possible to include 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. Can improve the solubility and thus the polymerization activity.

The polymerization temperature in the production method of the present invention is-
It is carried out at 30 to 150 ° C, preferably 10 to 120 ° C, particularly preferably 30 to 100 ° C. The polymerization reaction system can be used in either a batch method or a continuous method. Further, prior to the polymerization, in the presence or absence of the conjugated diene monomer, it is also possible in the production method of the present invention to carry out a pre-reaction or thermo-reaction of some or all of the catalyst components. is there.

In the production method of the present invention, a coupling agent is added after the polymerization reaction has achieved a predetermined polymerization rate,
The reaction increases the polymer molecular weight or branches the polymer chain. The amount of the coupling agent used is considered to be an amount that is equivalent to the amount of the polymerization active terminal, and is the optimum amount for the maximum increase in the molecular weight or the maximum branching. However, any range of coupling agent amounts can be used, depending on the degree of coupling desired.

In general, 0.01 to 1.5 equivalents, preferably 0.1 to 1.5 equivalents, per carbon-metal bond of organoaluminum.
Used at 1.0 equivalent of coupling agent. in this case,
Since the carboxylic acid ester compound undergoes an addition reaction with two polymer active terminal molecules per ester bond unit and the carbonate compound with three active polymer terminal molecules per carbonate bond unit, it is necessary to consider the equivalent number calculation. The coupling agent can be added alone or as an inert hydrocarbon solution. The coupling agent can be added all at once, dividedly or continuously. The coupling reaction varies depending on the reactivity, but is usually performed at a temperature close to the polymerization temperature for several minutes to several hours.

In the production method of the present invention, after performing a coupling reaction, if necessary, a polymerization terminator and a polymer stabilizer are added to the reaction system, and a known solvent removal and drying operation in the production of a conjugated diene polymer is carried out. For example, the polymer can be recovered by steam stripping drying, heating drying, or the like.

The polymerization terminator can be selected from water, a protic polar organic compound and the like. Examples of the latter include various alcohols, phenols, and carboxylic compounds.

The polymer stabilizer can be selected from known conjugated diene polymer stabilizers and antioxidants. Particularly preferred examples thereof include 2,6-di-tert-butyl-4-methylphenol, trinonylphenyl phosphate, phenyl-β-naphthylamine, N, N′-dialkyldiphenylamine, and N-alkyldiphenylamine.

[0043]

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

Example 1 and Comparative Example 1 The inside of a well-dried 1000 ml pressure-resistant autoclave was sufficiently replaced with dry nitrogen and used for polymerization. Example 1
After 600 g of a mixed solution of cyclohexane containing 90 g of 1,3-butadiene was injected into the autoclave, 0.27 mmol of neodymium 2-isopropyl-5-methylhexanoate, 4.4 mmol of diisobutylaluminum hydride, and ethylaluminum sesquichloride were dissolved in Cl 2. /
Nd was added so that the element ratio became 3, and polymerization was performed at 50 ° C. for 2 hours. After the polymerization, 0.38 mmol of butyl trimellitate was added as a coupling agent and reacted at 50 ° C. for 1 hour. After the reaction, BHT [2,6-bis (tert-
[Butyl) -4-methylphenol] was stopped with 10 ml of a 10 wt% methanol / siloxane mixture solution, and the polymer was separated with a large amount of methanol.
Vacuum dried at 0 ° C.

Comparative Example 1 was carried out under the same conditions as in Example 1 except that no coupling agent was added. Table 1 shows the measurement results of the polymer thus obtained, such as the yield, 1,4-cis content, and molecular weight. FIG. 1 shows the GPC measurement results.

[0046]

[Table 1]

(3) Analytical method (1) The 1,4-cis content was measured using an infrared spectrophotometer, and data was obtained by a Morello method. (2) The molecular weight was measured by gel permeation chromatography using THF (tetrahydrofuran) as a developing solvent. (3) GPC data peak analysis is performed for the coupling ratio to show the weight content of the coupling polymer contained in the polymer.

Examples 2 to 5 In Examples 2 to 5, the following Tables were used instead of butyl trimellitate.
Using the coupling agent described in 2 in the amount described in the table,
Other polymerization conditions were the same as in Example 1.
Table 2 shows the results.

[0049]

[Table 2]

Examples 6 to 8 Examples 6 and 7 were carried out in the same manner as in Example 1 except that diethyl carbonate was used as a coupling agent in place of butyl trimellitate and the addition amount shown in Table 3 was used. did. Table 3 shows the results.

[0051]

[Table 3]

Examples 9 to 11 Examples 9 to 11 were carried out in the same manner as in Example 1 except that the organic neodymium shown in Table 4 was used instead of neodymium 2-isopropyl-5-methylhexanoate. did. Table 4 shows the results.

[0053]

[Table 4]

Example 12 In Example 12, a glass bottle was prepared by adding 0.27 mmol of neodymium 2-isopropyl-5-methylhexanoate and 4.4 mmol of diisobutylaluminum hydride in a nitrogen atmosphere in the presence of a small amount of a butadiene monomer in advance. The mixture was preliminarily reacted for 10 minutes, and ethyl aluminum sesquichloride was further added so as to have an element ratio of Cl / Nd = 3, followed by aging for 1 hour. The polymerization temperature was 45 ° C., the polymerization time was 8 hours, and the other conditions were the same as in Example 1. Table 5 shows the results.

[0055]

[Table 5]

Examples 13 to 15 Examples 13 to 15 were carried out in the same manner as in Example 1 except that the organic aluminum shown in Table 6 was used instead of diisobutylaluminum hydride. Table 6 shows the results.

[0057]

[Table 6]

Examples 16 to 18 In Examples 16 to 18, a halogen-containing Lewis acid shown in Table 7 was used instead of ethylaluminum sesquichloride.
The polymerization was carried out in the same manner as in Example 1 except that the polymerization was performed so that 1 / Nd = 3 element ratio. Table 7 shows the results.

[0059]

[Table 7]

[0060]

According to the present invention, there is provided a conjugated diene system having a high cis 1,4-bond content, an increased molecular weight or a branched structure of a polymer molecular chain, excellent rubber properties and processing performance, and low solution viscosity. An object of the present invention is to provide a method for producing a polymer with high efficiency. The resulting polymer is used in various applications that take advantage of its excellent rubber properties and processing characteristics, for example, if necessary, by mixing with other synthetic rubbers or natural rubbers, and treads, carcass, sidewalls, bead portions, and other tire components. Or for automotive parts such as hoses, window frames, belts, raw rubber for vibration damping rubber, industrial products, and also as a resin reinforcing agent such as impact-resistant polystyrene and ABS resin. Performance and effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of GPC measurement of the polymers of Example 1 and Comparative Example 1.

[Explanation of symbols]

 1 Polymer of Example 1 2 Polymer of Comparative Example 1

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08F 4/00-4/82

Claims (3)

(57) [Claims] (A) The general formula LnY ₃ (where Ln is a rare compound )
An earth element, Y represents an acid residue), an organic compound of a rare earth element represented by (b) an organoaluminum compound and (c) an element belonging to IIIb, IVb or Vb of the periodic table
Condensed dienes are subjected to bulk polymerization or solution polymerization in a hydrocarbon solvent in the presence of a composite catalyst comprising a halogen-containing Lewis acid compound selected from halides , and then an ester compound of carboxylic acid and alcohol or phenol and carbonic acid and alcohol Alternatively, a method for producing a novel conjugated diene-based polymer, wherein a coupling agent selected from an ester compound with phenol is added and reacted. 2. A coupling agent comprising a compound selected from a carboxylate compound defined by the following general formula (1) and a carbonate compound defined by the following general formula (2): A method for producing the conjugated diene-based polymer according to claim 1. Embedded image Embedded image Here, R ¹ is an aliphatic, alicyclic or aromatic hydrocarbon group having ¹ to 10,000 carbon atoms, and n is 1 to
It is an integer in the range of 5,000. R ² , R ³ and R ⁴ are an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 50 carbon atoms. 3. The method according to claim 1, wherein the conjugated diene is 1,3-butadiene and / or isoprene.