JP2000080116A - Preparation of conjugated diene polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymerization process for preparing a conjugated diene polymer using a monoorganolithium compound or polyfunctional organolithium compound as a polymerization initiator, wherein the polymerization rate is high even when polymerized at a relatively low polymerization temperature and therefore a conjugated diene polymer with a small amount of gel formation is obtained, and regulation in the bonding structure of a conjugated diene unit in the resultant polymer is not regulated by a polar compound. SOLUTION: When carrying out anionic polymerization using an organic monolithium compound or polyfunctional organic lithium compound as a polymerization initiator, polymerization of a conjugated diene is carried out at a polymerization temperature of from 0 to 140 deg.C in a non-polar hydrocarbon solvent in the presence of a π complex compound comprising a benzene ring compound having a substituent in a molar ratio against polymerization initiator active points of the πcomplex compound within the range of from 1/10 to 1,000/1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel method for producing a conjugated diene polymer using a polymerization initiator comprising a monoorganic lithium compound or a polyfunctional organolithium compound.

[0002]

2. Description of the Related Art Attempts to polymerize a conjugated diene using a monoorganic lithium compound or a polyfunctional organolithium compound as a polymerization initiator have been studied for a long time, and commercial production is currently being carried out. For example, they use n-butyllithium or sec-butyllithium as a polymerization initiator and polymerize butadiene or isoprene in a non-polar hydrocarbon solvent by a batch method or a continuous method. It is used after being crosslinked. Specific applications include tires, belts, hoses, etc., as well as rubber for rubber-modified polystyrene.

In the anionic polymerization of a conjugated diene, a polar compound such as an amine compound or an ether compound is used to increase the polymerization rate or to enhance the copolymerizability with an aromatic monovinyl compound. The bond structure of the conjugated diene is changed by the polar compound,
The resulting polymer has an increased content of 1,2-vinyl bonds or 3,4-vinyl bonds. Further, in normal commercial production, polymerization is carried out at a polymerization temperature of 60 to 140 ° C. in order to increase the polymerization rate and improve productivity. The formation of a degraded polymer is recognized, and the product quality is degraded.

Studies have been made to increase the polymerization rate in nonpolar hydrocarbon solvents without using polar compounds. For example,
It is known that the use of durene as a π-electron donor in anionic polymerization changes the polymerization rate of styrene. J. of Polymer Science, Part A, 3, 1037-1044, (196
According to 5), in a non-polar hydrocarbon solvent, when the molar ratio of durene to the polymerization active terminal Li is 1/5, the polymerization rate of styrene is about 2 times as compared with the case without durene.
It is reported to be twice as large, and there is a description suggesting the formation of a π complex by durene. However, there was no suggestion of an attempt to polymerize a conjugated diene polymer by actively using a π-complexing compound such as durene.

In the commercial production of conjugated diene polymers by anionic polymerization in a conventional non-polar hydrocarbon solvent, a high polymerization temperature is employed with an emphasis on productivity, and batch polymerization or continuous polymerization at a high polymerization rate is performed. The polymerization temperature is 60
~ 140 ° C is used. However, at a polymerization temperature exceeding 100 ° C., a crosslinking reaction proceeds due to a double bond based on a conjugated diene, or a polymerization active terminal reacts with another polymer,
A polymer having a molecular weight exceeding a target molecular weight is generated by the generation of a branched structure by bonding, and in a severe case, a gel having a molecular weight that is insoluble in a solvent is generated, and a product with reduced product quality is obtained. On the other hand, when polymerization is carried out at a temperature of 20 to 60 ° C. in a non-polar hydrocarbon solvent not using a polar compound, the polymerization reaction rate is low, so that there is a disadvantage that the polymerization takes a long time to complete.

[0006] The polymerization reaction rate can be increased by using a polar compound such as the above-mentioned amine compound or ether compound, or by performing polymerization in a polar solvent. However, in this case, the microstructure of the obtained conjugated diene polymer changes and the content of 1,2-vinyl bonds or 3,4-vinyl bonds increases. As a result, the secondary transition temperature and Tg of the obtained conjugated diene polymer are increased, and the low-temperature characteristics of the polymer are impaired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to produce a conjugated diene polymer using a monoorganic lithium compound or a polyfunctional organolithium compound as a polymerization initiator at a relatively low polymerization temperature. However, it is an object of the present invention to provide a polymerization method in which a conjugated diene polymer having a high polymerization reaction rate and hence a small amount of gel formed can be obtained, and the binding structure of the conjugated diene caused by the polar compound is not restricted.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to overcome the above-mentioned drawbacks relating to the production of a conjugated diene polymer using a monoorganic lithium compound or a polyfunctional organolithium compound as a polymerization initiator. As a result, the following invention was completed. That is, the present invention uses a monoorganic lithium compound or a polyfunctional organolithium compound as a polymerization initiator in the presence of a π-complexed compound comprising a benzene ring compound having a substituent to polymerize a conjugated diene in a nonpolar hydrocarbon solvent. To a method for producing a conjugated diene polymer.

In one embodiment of the present invention, in an anionic polymerization using a monoorganic lithium compound or a polyfunctional organolithium compound as a polymerization initiator, a π-complexed compound composed of a benzene ring compound having a substituent is replaced with a π-complexed compound. The molar ratio of the complexing compound to the polymerization initiator active site is 1/10 to 10
A method of producing a conjugated diene polymer in which a conjugated diene is polymerized in a nonpolar hydrocarbon solvent at a polymerization temperature of 0 to 140 ° C. in the range of 00/1. As the non-polar hydrocarbon solvent to be used, aliphatic hydrocarbons having 4 to 8 carbon atoms, alicyclic hydrocarbons or mixtures thereof can be used, but n-hexane and cycloalkanes, particularly cyclohexane, cyclopentane Is preferred.

Examples of the monoorganic lithium compound used as a polymerization initiator include n-butyllithium, sec-butyllithium, tert-butyllithium, 2-methyl-propyllithium, i-propyllithium and the like. Lithium, sec-butyllithium, t
tert-Butyl lithium is preferred. The amount of the monoorganic lithium compound to be used is appropriately changed depending on the molecular weight of the target block copolymer and the amount of the polymerization inactivating component caused by the reaction vessel and the like. The polymerization initiator containing a polyfunctional organolithium compound having an active site of three or more functional groups used in the present invention is an active site having a polymerization activity obtained by reacting the above monoorganic lithium compound with another compound. It is a polymerization initiator containing at least 5% by weight or more of a trifunctional or higher polyfunctional organolithium compound.

[0011] Of these examples, particularly representative ones are:
It is a reaction product containing a monoorganic lithium compound and a polyvinyl aromatic compound. For example, a reaction product of a monoorganic lithium compound and a polyvinyl aromatic compound, a reaction product of reacting a monoorganic lithium compound with a conjugated diene monomer, and then reacting with a polyvinyl aromatic compound, or a monoorganic lithium compound A reaction product of reacting a compound with an aromatic monovinyl compound and then reacting with a polyvinyl aromatic compound, or a monoorganic lithium compound and a conjugated diene monomer or an aromatic monovinyl compound, and a polyvinyl aromatic compound. A reaction product or the like obtained by simultaneously reacting the components is used. Further, a catalyst obtained by reacting a reaction product of a monoorganic lithium compound with an aromatic monovinyl compound with a polyvinyl aromatic compound and then further reacting the aromatic monovinyl compound is also effective.

Specific methods for producing a polymerization initiator containing a polyfunctional organolithium compound having three or more functional active points are described in JP-A-57-40513 and JP-A-57-40.
No. 514, Japanese Unexamined Patent Publication No. 2-229809, and the like. For example, the reaction can be adjusted under the condition that the moles of divinylbenzene and n-butyllithium are 0.05 to 0.5, or the reaction can be adjusted by further adding butadiene. From the produced polyfunctional organolithium compound having three or more functional active sites, a polymer having a so-called radial structure or radial structure can be produced.

The π-complexed compound comprising a benzene ring compound having a substituent is a compound which participates in the association of an organolithium compound or a lithium ion having polymerization activity and has a function of partially dissociating the association. A compound which does not react with an organic lithium compound or a lithium ion having polymerization activity or has a reaction rate sufficiently lower than the polymerization rate of a monomer. They include compounds having a benzene ring, benzene substituted with three or more alkyl groups, dodecahydrotriphenylene, diphenyl-substituted methylene compounds, and 1,1-diphenyl-substituted ethylene compounds.

Specifically, in addition to the above-mentioned dodecahydrotriphenylene, 1,2,4,5-tetramethylbenzene (durene), hexamethylbenzene, 2,2-diphenylpropane, and tetraphenylethylene are exemplified.
These π-complexing compounds are used in a molar ratio of 1/10 to 1000/1 with respect to the total number of active sites of the polymerization initiator. The optimum range varies depending on each compound. / 1, but also limited by the solubility in the solvent used.
These π-complexed compounds and the polymerization initiator composed of a monoorganic lithium compound or a polyfunctional organolithium compound can be mixed in advance, but they can be separately added to the polymerization solvent before adding the polymerization monomer. Is preferred. Further, it is appropriate to add the two and mix them with stirring immediately before the introduction of the monomer.

It is necessary that the starting materials and the solvent used in the reaction are sufficiently purified before use. It is necessary to consider the impurities brought in from the reaction vessel and the like. The monomers used for the polymerization reaction are also appropriately purified. The conjugated diene used for producing the polymer is a monomer usually used in anionic polymerization. For example, as the conjugated diene, butadiene, isoprene, 2-ethyl-1,3-
Butadiene, 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene, 1,3-cyclohexadiene and the like. Other monomers used for producing the copolymer include styrene, α-methylstyrene, p-methylstyrene, m
-Methylstyrene, o-methylstyrene, p-tert
-Butylstyrene, 1,1-diphenylethylene, and vinylnaphthalene. As other monomers, divinylbenzene, (meth) acrylates, vinylpyridine, and ε-caprolactone can also be used as the copolymerization component.

A block copolymer can also be produced using the above-mentioned monomers. As a method of polymerizing a block copolymer having a linear structure using a monoorganic lithium as a polymerization initiator, there are usually a method in which monomers are sequentially added and a method in which a block copolymer is prepared by utilizing the reactivity ratio of monomers. The latter is, for example, a method in which a conjugated diene and an aromatic monovinyl compound are simultaneously charged into a polymerization reaction vessel.First, polymerization of the conjugated diene starts, and a copolymerized portion of the conjugated diene and the aromatic monovinyl compound is gradually formed, and finally, A homopolymer of the aromatic monovinyl compound is formed. In the case of a block copolymer having a radial structure, a method of coupling a block copolymer of an aromatic monovinyl compound having a polymerization active terminal and a conjugated diene, or a respective homopolymer having a polymerization active terminal with a coupling agent. And a method of previously synthesizing a polyfunctional polymerization initiator and polymerizing a block copolymer by a method similar to the polymerization method using a monoorganic lithium compound as a polymerization initiator.

A conjugated diene or aromatic monovinyl compound is used in a nonpolar hydrocarbon solvent in the presence of a monoorganic lithium compound or a polyfunctional organolithium compound as a polymerization initiator in the presence of a π-complexed compound comprising a benzene ring compound having a substituent. When polymerizing the compound alone, a polar compound is unnecessary. However, a small amount of a polar compound is required when polymerizing a block copolymer in which an aromatic monovinyl compound is polymerized subsequently to a conjugated diene or a random copolymer thereof. This is because when only the π-complexed compound is present in the non-polar solvent, butadienyllithium which is the polymer active end of the conjugated diene does not react with the aromatic monovinyl compound, so that polymerization does not proceed, but a small amount of the polar compound This is because the coexistence of the compound initiates the polymerization of the aromatic monovinyl compound to form a copolymer for the first time. Examples of the polar compound include ether compounds such as tetrahydrofuran (THF), diethoxypropane, glyme, and diglyme, and tertiary amines such as triethylamine and tetramethylethylenediamine. These polar compounds have a concentration of 0.1.
1% or less is appropriate. When used as a solvent for polymerizing a conjugated diene, a very small amount, for example, 10
About 300 ppm. The preferred polar compound is TH
F.

The polymer obtained by polymerization using the monoorganic lithium compound and the polyfunctional organic lithium compound of the present invention as a polymerization initiator has a lithium anion terminal having polymerization activity at each polymer terminal, and the activity A polar group can be introduced using the terminal. For example, when reacted with ethylene oxide, a telechelic polymer having a hydroxyl group at a terminal can be obtained. When reacted with carbon dioxide and hydrolyzed, a polymer having a terminal carboxylic acid group is obtained. According to this method, for example, a polymer having a functional group at the terminal of a conjugated diene polymer having a small 1,2-vinyl structure can be synthesized.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. The solvent, durene and monomer were purified by dehydration and distillation to remove impurities. Tetraphenylethylene was purified by repeating recrystallization and sublimation. In particular, monomers were distilled quickly. The concentration of the purchased cyclohexane solution of n-butyllithium (hereinafter referred to as “n-BuLi”) was determined by titration and used.

Example 1 Bd with n-butyllithium initiator using durene
Polymerization of 10 Using a 10-liter autoclave with a stirrer, 6
The butadiene was polymerized at 5 ° C. Using a cyclohexane solvent, 0.05 parts by weight of n-BuLi and n-BuL
Durene having a molar ratio of 20 times i was charged into the reactor, and after 10 minutes, 100 parts by weight of butadiene was charged. The butadiene concentration was about 5% by weight. The resulting polybutadiene is
According to GPC, the number average molecular weight (Mn) was 150,000, and the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mw / Mn) was 1.
04. The microstructure determined by the Morero method based on the infrared absorption spectrum indicates that the 1,2-vinyl structure has 12
%, The 1,4-cis structure was 38%, and the 1,4-trans structure was 50%.

Comparative Example 1 Polymerization of Bd In the same manner as in Example 1, butadiene was polymerized without adding durene. The resulting polybutadiene is GPC
From that the number average molecular weight (Mn) is 145,000 and the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mw / Mn) is 1.0
It was 7. The microstructure determined by the Morero method based on the infrared absorption spectrum has a 1,2-vinyl structure of 12%,
37% 1,4-cis structure, 5% 1,4-trans structure
1%.

(Example 2) Measurement of polymerization rate The polymerization rate of butadiene at 20 ° C was measured using durene. Butadienyl lithium active terminal concentration is 10
^-3 mol / liter (hereinafter referred to as M) was used.

[Table 1] It is found that the use of durene increases the polymerization rate of butadiene.

[0023]

According to the present invention, even when a conjugated diene polymer is polymerized at a relatively low polymerization temperature using a monoorganic lithium compound or a polyfunctional organolithium compound as a polymerization initiator, the polymerization reaction rate is high. In addition, a conjugated diene polymer having a small amount of gel can be obtained. Further, since a polar compound containing nitrogen or oxygen that regulates the bonding structure of the conjugated diene polymer is not used, the amount of 1,2-vinyl bond or 3,4-
Since the amount of vinyl bonds is minimized, it is possible to obtain a polymer whose amount is freely controlled by adding an appropriate amount of a polar compound to increase the amount of the bonds. In addition, even when hydrogenating the obtained polymer, since a polar compound containing a nitrogen atom is not used, the polymerization solution can be directly used for a hydrogenation reaction using a catalyst poisoned by the polar compound.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Marcel Van Behren University of Leven Ceres Taynenran 200F B-3001 Hevely Belgium F-term (reference) 4J011 AA03 AA05 AA06 HA03 HA04 HB22 HB27 4J015 DA02 DA33 4J100 AB00Q AB02Q ABQ AB03 AB AL08Q AQ12Q AR18P AS01P AS02P AS03P AS04P BC43Q CA01 CA04 FA03

Claims (7)

[Claims] A conjugated diene is polymerized in a nonpolar hydrocarbon solvent using a monoorganic lithium compound as a polymerization initiator in the presence of a π-complexed compound comprising a benzene ring compound having a substituent. A method for producing a diene polymer. 2. In a non-polar hydrocarbon solvent, a polymerization initiator containing a polyfunctional organolithium compound having three or more functional sites is used in the presence of a π-complexing compound comprising a benzene ring compound having a substituent. A method for producing a conjugated diene polymer, comprising polymerizing a conjugated diene with 3. A π-complexed compound comprising a benzene ring compound having a substituent selected from benzene, dodecahydrotriphenylene, a diphenyl-substituted methylene compound, and a 1,1-diphenyl-substituted ethylene compound substituted with three or more alkyl groups. The method for producing a conjugated diene polymer according to claim 1, wherein the compound is at least one compound. 4. The benzene substituted with three or more alkyl groups is 1,2,4,5-tetramethylbenzene (durene) or hexamethylbenzene, and the diphenyl-substituted methylene compound is 2,2-diphenylpropane. Yes,
The method for producing a conjugated diene polymer according to any one of claims 1 to 3, wherein the 1,1-diphenyl-substituted ethylene compound is tetraphenylethylene. 5. The method for producing a conjugated diene polymer according to claim 1, wherein the monoorganic lithium compound is n-butyllithium sec-butyllithium or tert-butyllithium. 6. The method for producing a conjugated diene polymer according to claim 1, wherein the molar ratio of the π-complexed compound to the total active sites of the polymerization initiator is in the range of 1/10 to 1000/1. . 7. The method for producing a conjugated diene polymer according to claim 1, wherein the nonpolar hydrocarbon solvent is a solvent containing 0.1% or less of a polar compound.