JPH0210164B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing conjugated diene polymers and copolymers of conjugated dienes and other conjugated dienes having high trans-1,4 bond content and narrow molecular weight distribution using a novel composite initiator. It has been well known that conjugated dienes are polymerized in a highly stereoregular manner by a so-called Ziegler catalyst, which is mainly composed of a transition metal compound such as nickel, cobalt, titanium, or vanadium. When trying to obtain a polymer with a high trans bond content, it is generally sufficient to use a catalyst containing a vanadium compound as the main component, and in this case, the trans bond content is 90 to 95% in the case of a butadiene polymer.
can be easily obtained. However, trans-polybutadiene, which has such high stereoregularity, exhibits strong crystallinity at room temperature and exhibits characteristics of thermoplastic resin rather than rubber elastic material, and is used for the skin of golf balls, etc., but it is also used for tires. It was never used for so-called rubber purposes, such as raw material rubber. On the other hand, diene polymers obtained by so-called anionic polymerization using organolithium compounds do not have a high degree of stereoregularity, and for example, butadiene polymers generally exhibit the following microstructure. Trans 1,4 bond 50-55% Cis 1,4 bond 35-40〃 1,2 vinyl bond 10-15〃 Also, according to the organolithium initiator, unlike the case of the Ziegler catalyst mentioned above, dienes alone can be used. Copolymerization with vinyl aromatic hydrocarbons is also practically possible. However, in the copolymerization of dienes and vinyl aromatic hydrocarbons using organolithium initiators, there is a large difference in the copolymerization reactivity of the two, so various measures are required to obtain completely random copolymers of the two. shall be. To obtain completely random copolymers of conjugated dienes and vinyl aromatic hydrocarbons, there are two methods: adding polar compounds such as ethers, thioethers, amines, etc. to the polymerization system, or adding alkali metals other than lithium, such as potassium. A method of coexisting organic compounds is known (Special Publication No. 36-15386).
No., Special Publication No. 44-20463, etc.). However, although these methods are effective as randomizing agents for the copolymerization of dienes and vinyl aromatic compounds, on the other hand, from a microstructural perspective, they do not increase the number of 1, 2 or 3, 4 bonds to a greater or lesser extent. Typically, an increase in 1,2 or 3,4 bonds results in a higher glass transition temperature than 1,4 bonds, which is undesirable in some applications. It is also known to coexist a barium compound such as barium tert-butoxide in a system using an organolithium compound as an initiator (Japanese Patent Publication No. 47-3728).
issue). According to this method, the copolymerization of conjugated dienes and vinyl aromatic compounds is randomized without increasing the number of 1,2 or 3,4 bonds. However, the trans bond content is maximum at about 65% in the case of polybutadiene obtained in cyclohexane, a preferred solvent with low molecular weight loss, compared to unprocessed polybutadiene obtained using organolithium compounds alone. No particular superiority in physical properties or processability of the sulfur or vulcanizate was found. Recently, the following initiators have become known as initiators that can achieve even higher trans bond content and, in some cases, randomize the copolymerization of conjugated dienes and vinyl aromatic hydrocarbons. It became. (a) Complex consisting of barium tertiary alkoxide and dibutylmagnesium (Special Publication No. 48910 of 1983). (b) A complex of organolithium and a barium compound of the following formula (Japanese Patent Application Laid-Open No. 1983-9090). (c) A composite cocatalyst consisting of an organolithium, barium or strontium compound and an organometallic compound B or A (Japanese Patent Publication No. 30543/1983). (d) Organolithium and Me [MR ¹ R ² R ³ R ⁴ ] ₂ or Me
[M′(R)′ ₄ ] complex (wherein Me is Ba, Ca,
(Sr or Mg, M represents B or Al, M' represents Zn) (Japanese Patent Application Laid-Open No. 17591/1983). (e) Organolithium, Ba, Sr or Ca compound,
A complex consisting of an organometallic compound of B or A, an alkali metal alcoholate, etc.
- No. 98077). Butadiene polymers obtained using these initiators have a trans 1,4 bond content of approximately 65 to 85%, and especially when the trans content exceeds about 75%, they are highly green as tire raw rubber. It indicates strength. However, each of these methods has drawbacks that are considered problematic in industrialization, albeit in different ways. That is, in the method using the complex shown in (a) above, the solubility of each component constituting the complex in the hydrocarbon solvent is insufficient, and in particular, the magnesium compound can only be used in a limited amount due to solubility. . Moreover, 75%
When producing a polymer having such a high trans-1,4 bond content, the polymerization activity of the initiator is relatively low, and the molecular weight of the resulting polymer is also low. Therefore, the vulcanized physical properties of the polymer are not sufficient for applications such as tire raw materials. In the method using a complex shown in (b), extremely complicated operations are required to prepare the barium compound complex itself, and in some cases, polymerization activity may not be found immediately, making it impossible to reproduce. There is. Further, the molecular weight distribution Mw/Mn is 4 to 4.0, and it is clear that such a wide molecular weight distribution causes deterioration of the vulcanized physical properties. In contrast, in the method using a composite cocatalyst shown in (c), it is relatively easy to adjust the catalyst components, and each component has sufficient solubility in hydrocarbon solvents, and from this point of view, it is a preferable catalyst. It can be said. however,
As shown in the specification, transformer 1,
In order to obtain a relatively high 4-bond content, it is necessary to increase the proportion of the organometallic compound of metal B or A used, which reduces the molecular weight of the resulting polymer (as indicated by the intrinsic viscosity). ) or have the disadvantage of lowering the copolymerizability of styrene. Although the methods (d) and (e) proposed to improve this point certainly improve the drawbacks of the method (b) above, they are still not sufficient, especially in improving the copolymerizability of styrene. Not enough. Moreover, method (d) requires complicated operations to prepare the barium complex, and the resulting barium complex is poorly soluble in paraffinic hydrocarbon solvents such as n-hexane.
Although the method (e) does not have these drawbacks, the total amount of catalyst required to produce per monomer weight of the polymer, expressed as the sum of the catalyst components, is extremely high.
In its industrialization, not only economic efficiency becomes a problem, but also new problems are expected to arise, such as the need to remove catalyst residues in the polymer. The present invention improves the above-mentioned drawbacks of the prior art by using a new composite initiator that simply combines catalyst components that are easy to adjust and have sufficiently high solubility in hydrocarbon solvents. A conjugated diene polymer having a high trans-1,4 bond content and a narrow molecular weight distribution can be produced in good yield. Furthermore, in the copolymerization of a conjugated diene and a vinyl aromatic compound, a copolymer with a high content of bound styrene and having improved copolymerizability can be easily produced. That is, the present invention provides a method for producing a conjugated diene polymer, a copolymer of a conjugated diene with another conjugated diene, or a copolymer of a conjugated diene with a vinyl aromatic compound. - Consists of a magnesium compound (B) and an organoaluminium compound (C), and the molar ratio of compound (B) to compound (A) is 1 to 2, and the molar ratio of compound (C) is 1 to 3. This is a method for producing conjugated diene polymers having a high trans-1,4 bond content and a narrow molecular weight distribution, which is characterized by carrying out the reaction in the presence of a complex initiator. As described above, in the production method of the present invention, all the initiator components are soluble in a hydrocarbon solvent, and the polymerization operation can be easily carried out without requiring complicated preliminary adjustments. Examples of conjugated dienes used in the present invention include 1,3-butadiene, isoprene, 2,3-
Dimethyl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 2-phenyl-
Examples include 1,3-butadiene and 1-phenyl-1,3-butadiene. Further, examples of the vinyl aromatic compound used in the present invention include styrene, divinylbenzene, vinyltoluene, 1-vinylnaphthalene, α-methylstyrene, methoxystyrene, and the like. The most preferred practical form of polymerization of the present invention is
It is a polymer of butadiene alone or a copolymer of styrene and butadiene. The organic compound (A) of barium, which is the first component of the composite initiator used in the present invention, can be expressed by the following formula, and among these, particularly preferred are alcohol or phenol salts of barium. (In the formula, R is selected from aliphatic, alicyclic or aromatic hydrocarbon groups, and Y is an oxygen or sulfur atom.) Examples of these include barium salts of the following compounds. It will be done. Namely, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, tert-butyl alcohol, n-hexyl alcohol, cyclohexyl alcohol, allyl alcohol, cyclopentenyl alcohol, benzyl alcohol, phenol, catechol, 1-naphthol, 2,6
-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, nonylphenol, 4-phenylphenol, ethanethyl, 1
-Butanethyl, thiophenol, cyclohexanethiol, 2-naphthalenethiol, caprylic acid, lauric acid, myristic acid, palmitic acid,
Stearic acid, oleic acid, linoleic acid, linoleic acid, naphthoic acid, benzoic acid, hexanethylic acid, decanethylic acid, tridecanethionolic acid,
Thiobenzoic acid, acidic tert-butyl carbonate, acidic hexyl carbonate, acidic phenyl carbonate, thioacidic tert-carbonate
-butyl, dimethylamine, diethylamine, di-n-butylamine, etc. The organolithium-magnesium compound (B), which is the second component of the composite initiator of the present invention, can be obtained by reacting an organolithium compound and an organomagnesium compound. The organolithium-magnesium compound resulting from this reaction must be formed in advance by dissolving the initiator component in a hydrocarbon solvent before mixing barium, which is the first component of the composite initiator, with the organic compound or adding it to the polymerization system. Preferable from the viewpoint of sex. However, if the solubility of each component is sufficient, the two may be used separately without forming a complex of compound (B) in advance. Further, the reaction between the two is preferably carried out at a molar ratio of 1:1, but the present invention is not limited to this, and an excessive amount of unreacted organolithium compound or organomagnesium compound may be present. Particularly preferred organic lithium
Examples of the magnesium compound include lithium magnesium trialkyl. The organic lithium compound that can be used in the present invention can be expressed by the following formula. R(Li) _o (wherein R is selected from aliphatic, alicyclic or aromatic hydrocarbon groups, and n is an integer from 1 to 4) as an example of an organolithium compound The following can be mentioned. Namely, ethyllithium, n-propyllithium, iso-propyllithium, n-butyllithium, isoamyllithium, sec-amyllithium, n-hexyllithium, n-octyllithium, allyllithium, n-propenyllithium, iso-butenyl Lithium, benzyllithium, phenyllithium, 1,1-diphenylhexyllithium, tetramethylene dilithium, pentamethylene dilithium, hexamethylene dilithium, diphenylethylene dilithium, tetraphenylethylene dilithium, 1,5- Dilithium naphthalene, 1,4-dilithiocyclohexane,
These include polybutadienyllithium, polyisobutenyllithium, polystyryllithium, etc. The organomagnesium compound can be expressed by the following formula. R ₂ Mg (wherein R is selected from aliphatic, alicyclic or aromatic hydrocarbon groups) Examples of organomagnesium compounds include: That is, diethylmagnesium, di-n-propylmagnesium, di-iso-
Propylmagnesium, di-n-butylmagnesium, di-tert-butylmagnesium, di-n-
These include hexylmagnesium, di-n-propenylmagnesium, and diphenylmagnesium. The organoaluminum compound (C) which is the third component of the composite initiator of the present invention can be expressed by the following formula, and a particularly preferred compound is trialkylaluminum. R ₃ Al (wherein R is selected from aliphatic, alicyclic or aromatic hydrocarbon groups) Examples of organoaluminum compounds include the following. That is, tri-iso-butylaluminum, tri-n-propylaluminum,
Tri-iso-propyl aluminum, etc. The amount of initiator used depends on the polymerization purpose or polymerization method,
Although it varies widely depending on conditions,
The amount of component (A) constituting the composite initiator of the present invention is generally from 0.005 to 100 grams of total monomers.
Preferably it is 50 mmol. In the present invention, the molar ratio of compound B and compound (C) to compound (A) is limited to (B)/(A)=1-2 (C)/(A)=1-3. By using initiator components within these ranges, the present invention enables the production of conjugated diene polymers with high trans 1,4 bond content and narrow molecular weight distribution. When (B)/(A) is less than 1, the initiator activity decreases and the molecular weight distribution of the resulting polymer is broadened, which is not preferable. If (B)/(A) is 2 or more, the trans 1,4 bond content will decrease, which is not preferable. Also, even if (C)/(A) is less than 1, the transformer 1,
4 bond content decreases, which is not preferable. (C)/(A) is 3
Although it depends on the amount of component (B), the above is not preferable because the initiator activity and the copolymerizability of the conjugated diene and the vinyl aromatic compound are significantly reduced. The most preferred composite initiator is an initiator in which the compound (A) is an alcohol or phenol salt of barium, the compound (B) is a lithium/magnesium trialkyl, and the compound (C) is an aluminum trialkyl. Although polymerization using the composite initiator of the present invention can be carried out in bulk, it is generally preferable to carry out solution polymerization in a hydrocarbon solvent. Particularly useful hydrocarbon solvents include aliphatic or cycloaliphatic hydrocarbon compounds having from 3 to 10 carbon atoms, such as pentane, hexane, heptane, octane, cyclohexane, cyclooctane, etc., and mixtures thereof. Aromatic hydrocarbon compounds having 6 to 10 carbon atoms, such as benzene, xylene, ethylbenzene, etc., and mixtures thereof may also be used. These solvents may also contain small amounts of polar solvents, such as various ethers, thioethers, and amines. In addition, the polymerization temperature is preferably -40℃ to
The temperature is 160°C, particularly preferably 40°C to 120°C. The atmosphere of the polymerization system is preferably replaced with an inert gas such as nitrogen gas or argon gas. It is preferable to prevent compounds that react with organic metals, such as water, halogen compounds, and oxygen, from being mixed into the polymerization system. Conjugated diene polymers obtained in good yield with the above-described composite initiator of the present invention have a higher content of trans-1,4 bonds and a narrower molecular weight distribution than conventional polymers. Polymers with such high trans-1,4 bond content and narrow molecular weight distribution exhibit high unvulcanized material strength, high tensile strength during vulcanization, and low hysteresis loss represented by high rebound resilience, and are useful for tires, etc. It is a preferred raw material rubber for producing rubber products. EXAMPLES The present invention will be explained below using Examples, but the present invention is not limited to these Examples. Examples 1-2 In a pressure-resistant glass bottle with a capacity of about 1 filled with dry nitrogen, 100 g of 1,3-butadiene and 400 g of n-hexane as a solvent were added, an initiator was added with the components shown in Table 1, and 50 g of The polymerization reaction was carried out at ℃ for 7 hours. Table 1 shows the microstructure, yield, and intrinsic viscosity of the obtained polymer. Comparative Examples 1 to 5 Polymerization reactions were carried out in the same manner as in Examples 1 to 2, except that the composition of the composite initiator was changed to the composition shown in the Comparative Examples in Table 1. The results are shown in Table-1. Comparative Examples 6 to 9 Polymerization reactions were carried out in the same manner as in Example 1, except that the initiators shown in Table 2 were used. Display the results.
Shown in 2.

【table】

[Table] Examples 1 to 2 using the composite initiator of the present invention have higher trans
It is clear that a polymer with a bond content of 1.4 is given in high yield. In addition, by comparison with Comparative Examples 1 to 5, it was found that the present composite initiator was effective in yield, viscosity, and trans
1.4 It is clear that the composition is well-balanced and preferable in terms of bonding, etc. Example 3 0.9 kg of 1,3-butadiene and 3.6 kg of n-hexane (group) as a solvent were added to a reactor with a capacity of about 8 filled with dry nitrogen, and after raising the temperature to 70°C, the reaction was started as shown in Table 3. agent was added to initiate the polymerization reaction.
The reaction was run for 90 minutes. The temperature of the polymerization system rose to a maximum of 95°C due to heat generation during polymerization. Table 3 shows the microstructure, yield, and molecular weight of the obtained polymer.

[Table] Example 4 A single blend of the polymer obtained in Example 3 was prepared according to the formulation shown in Table 4, and the physical properties of the vulcanized product were evaluated. The results are shown in Table-5. The same composition and the same conditions as in Table 4 were used for comparison, except that emulsion polymerized styrene-butadiene copolymer rubber (SBR1502) and solution polymerized butadiene polymer rubber (manufactured by Asahi Kasei Corporation, trade name: NF50R) were used. A formulation was prepared and its physical properties were evaluated. The evaluation results are shown in Table 5. As shown in Table 5, the butadiene polymers having a high trans-1,4 bond content and narrow molecular weight distribution obtained by the method of the present invention are extremely excellent raw material rubbers having strong tensile strength and high impact resilience.

【table】

【table】

Claims (1)

[Claims] 1. In producing a polymer of a conjugated diene, a copolymer of a conjugated diene and another conjugated diene, or a copolymer of a conjugated diene and a vinyl aromatic compound, an organic compound of barium (A) , consisting of an organolithium-magnesium compound (B) and an organoaluminum compound (C), and the molar ratio of the compound (B) to the compound (A) is 1 to 2, and the molar ratio of the compound (C) to the compound (A). 1. A method for producing conjugated diene polymers having a high trans-1,4 bond content and narrow molecular weight molecules, characterized in that the reaction is carried out in the presence of a complex initiator whose trans-1,4 bond content is from 1 to 3. 2. The method for producing conjugated diene polymers according to claim 1, wherein the organic compound of barium (A) is an alcohol or phenol salt of barium. 3. The method for producing conjugated diene polymers according to claim 1, wherein the composite initiator comprises barium alcohol or phenol salt, lithium-magnesium-trialkyl, and trialkylaluminum. 4. The method for producing conjugated diene polymers according to claim 1, 2 or 3, wherein the copolymer of conjugated diene and vinyl aromatic compound comprises 1,3-butadiene and styrene.