JPH0376326B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a method for producing a diene polymer by stereoregularly polymerizing a conjugated diene in the presence of water. Production of stereoregular polymers using transition metals
It has been extensively studied since Ziegler's invention. The stereoregular polymerization method using transition metals is characterized by extremely high regularity of the microstructure of the resulting polymer. Emulsion polymerization, radical polymerization, etc. cannot produce a polymer with a regular microstructure. Polymers produced using transition metals have excellent regularity in microstructure. However, it also has the disadvantage of being extremely sensitive to oxygen and moisture. For example, as polymerization of diene monomers using transition metals, Ni
Polymerization of cis-polybutadiene using _the compound _-BF3OEt2 - _AlR3 system is known, but water is a strong polymerization inhibitor. In addition _{, cis-}
Water is also an extremely strong polymerization inhibitor in the polymerization of isoprene. Furthermore, it is known that the presence of water during the production of 1.2 polybutadiene using a catalyst system consisting of a cobalt compound, organoaluminium, and carbon disulfide reduces the polymerization activity (Japanese Patent Publication No. 1989-19892, Japanese Patent Publication No. 1989-1989). −5436). On the other hand, there are also examples of using water as a transition metal catalyst component. For example, cis polymerization of butadiene using a cobalt compound-AlEt ₂ Cl-H ₂ O system (MORRIS GIPPIN
I&E PRODUCT RESEARCH AND
DEVELOPMENT 1 , (1), 32 (1962),) and the 1.2 polymerization of butadiene using a cobalt phosphine complex -AlR ₃ -H ₂ O system are known (Japanese Patent Publication No. 44-
32426). However, in the former system, the optimal amount of water is
It is effective when H ₂ O/Al is in a very small amount around 0.2 (molar ratio), and it does not polymerize at all when a large amount of water is present. Also, in the latter system, the optimal amount of water is H ₂ O/Al =
It has a value of 0.5 to 1.0, and is effective when used in small amounts; if a large amount of water is present, polymerization will not occur at all. As shown in the above example, water has conventionally been considered to be effective in stereoregular polymerization using a transition metal as a catalyst, or to be a strong polymerization inhibiting substance even in a small amount. For this reason, in solution polymerization using transition metals, in order to remove oxygen and water from the solvent, special improvements are made to the recovery system and the solvent is purified. In particular, the water content in the solvent cannot often be sufficiently reduced by simple distillation, etc., and is treated using a column packed with a desiccant such as molecular sheep or silica gel. This not only complicates the process but also cannot be ignored in terms of manufacturing costs. Attempts have been made to perform polymerization using water as a transition metal catalyst, but no success has yet been achieved. The present inventors have conducted intensive studies and succeeded in polymerizing diene monomers by stereoregular polymerization using transition metals using a suspension polymerization method in the presence of a large amount of water, leading to the present invention. In the method for producing a diene polymer of the present invention, a cobalt compound (A) and a metal hydride compound (B) of a metal of Groups 1 to 3 of the periodic table are mixed in advance in an amount of 1 to 100 times the mole of (A). At least one selected from carbon disulfide, phenylisothiocyanate, and a xanthogen compound is added to the catalyst obtained by contacting the catalyst in the presence of a conjugated diene.
This method is characterized by polymerizing a conjugated diene in an aqueous system in the presence of a catalyst system in which species coexist. According to the present invention, since water coexists in the polymerization system enables polymerization in an aqueous system, the viscosity within the polymerization system can be reduced, and the temperature within the polymerization system can be easily controlled. be. Further, while conventional solution polymerization uses a large amount of solvent and therefore requires a recovery system, the present invention requires a small-scale recovery system or no recovery system at all. Furthermore, there is no need to perform difficult and complicated treatments such as dehydrating monomers, etc. in advance. The present invention makes it possible to polymerize diene monomers even in the presence of a large amount of water by preparing a catalyst in advance under specific conditions. The present invention will be explained in detail below. Examples of the cobalt compound (A) used in the method of the present invention include organic acid salts such as cobalt octylate, cobalt naphthenate, cobalt benzoate, cobalt oxalate, cobalt malonate, and cobalt acetate, cobalt bisacetylacetonate, Cobalt complexes such as cobalt trisacetylacetonate, cobalt acetoacetate ethyl ester, triphenylphosphine complex of cobalt bromide, trim-
Tolylphosphine complex, cobalt bromide trim-
Triarylphosphine complexes of cobalt halides such as xylylphosphine complexes, pyridine complexes of cobalt chloride, pyridine derivative complexes of cobalt halides such as β-picoline complexes of cobalt chloride, ethyl alcohol complexes of cobalt chloride,
(1,3-butadiene) [1-(2-methyl-3-
butenyl)-π-allyl]cobalt, tris-π
-Allyl cobalt, bicyclo-[3,3,0]-octidienyl-1,5-cyclooctadiene cobalt, bis-(π-allyl)-halogenocobalt (however, the halogen is either I, Br, or Cl) ), monovalent or zero-valent cobalt complexes such as octacarbonyl dicobalt. One type or two or more types of these cobalt compounds can be used. Hydrogenated metal compounds of metals from groups of the periodic table (B)
A compound that reduces a cobalt compound is preferably used. As the metals in the ~groups of the periodic table, metals in groups a, b, a, b, a, and b can be used, and among these, groups a, a, and a are preferable, and preferable metals include:
Examples include Li, Na, K, Mg, Zn, and Al, with Li and Al being particularly preferred metals. Preferred metal hydride compounds (B) are hydrogenated derivatives of the above-mentioned metals, and include metal hydride compounds such as lithium aluminum hydride, sodium poron hydride, and lithium poron hydride. These metal compounds can be used alone or in combination of two or more. The use of carbon disulfide and/or phenylisothiocyanate as component (C) used in the present invention is not particularly limited, but it is preferable to remove dissolved oxygen in advance by nitrogen bubbling or the like. As a xanthogen compound, the general formula

It is a compound having the formula: methylxanthate, ethylxanthate, n-propylxanthate, isopropylxanthate, n-butylxanthate, sec-butylxanthate, 6-butylxanthate, n
- xanthate acids such as pentylxanthate, n-hexylxanthate, n-heptylxanthate, n-octylxanthate, 2-ethylhexylxanthate, phenylxanthate, p-tolylxanthate, and lithium of these xanthate; sodium,
Potassium salts and dimethylxanthogen disulfide, diethylxanthogen disulfide, di-
n-propylxanthogen disulfide, diisopropylxanthogen disulfide, di-n-butylxanthogen disulfide, di-t-butylxanthogen disulfide, 2-ethylhexylxanthogen disulfide, diphenylxanthogen disulfide, ethyl Xanthogen disulfides such as phenylxanthogen disulfide are preferably used. Among these, xanthogen disulfide is particularly preferred, and dimethylxanthogen disulfide, diisopropylxanthogen disulfide, and diphenylxanthogen disulfide are particularly preferred. The method of preparing the catalyst used in the process of the invention is of critical importance. The method for preparing the catalyst used in the present invention is to first bring a specific amount of a cobalt compound (A) into contact with a metal hydride compound (B) of group 1 of the periodic table in the presence of a conjugated diene and cause the reaction. be. The molar ratio of conjugated diene/Co compound during this preparation is preferably 1 to 100, more preferably 6
-50, and the molar ratio of (B)/(A) is preferably 0.3-100, more preferably 0.9-50. The temperature during preparation is preferably -78°C to 100°C, more preferably -30°C to 50°C. By stirring the solvent and catalyst component as necessary during preparation, (A) and
The reaction with (B) can be carried out uniformly. Preferred solvents used for catalyst preparation include toluene, benzene, xylene, hexane, heptane, pentane, refined kerosene, and the like. Stirring is sufficient to mix the inside uniformly. The preparation time is affected by the temperature at the time of preparation, but it is usually 5 minutes to 2 minutes.
It takes about an hour. Component (C) may be added in advance to the aqueous suspension or emulsion of the monomer or monomer solvent solution, or added to the polymerization system simultaneously with the addition of the reaction product of the cobalt compound described above. Good too. Of these, the former is preferred.
The above (C) component is per mole of cobalt compound (A)
0.01-100 mol is preferable, and 0.3-10 mol is more preferable. The water used in the polymerization of the present invention is preferably water from which dissolved oxygen has been removed by nitrogen bubbling or the like. The amount of water is the amount necessary to bring the water and the diene monomer or the solution of the diene monomer in the solvent into a suspended state. The preferred amount of water is the volume ratio of the diene monomer or diene monomer solution.
It is 0.2 times or more, more preferably 1 time or more. If the amount of water is too large, the polymerization efficiency per reaction volume will decrease. The conjugated diene used in the present invention is preferably a conjugated diene having 4 to 5 carbon atoms, such as butadiene or isoprene. Further, in addition to the conjugated diene, a small amount of other monomers such as olefin can also be coexisting in the polymerization system. The present invention involves polymerizing a conjugated diene monomer in an aqueous system. Examples of aqueous polymerization include suspension polymerization and emulsion polymerization, but suspension polymerization is preferred. Further, in the aqueous polymerization, an organic solvent that dissolves the conjugated diene monomer can be used as necessary. Organic solvents for dissolving monomers during polymerization include aromatic hydrocarbon solvents such as benzene, toluene, and xylene; pentanehexane, heptane,
Aliphatic hydrocarbon solvents such as octane; halogenated hydrocarbon compounds such as methylene chloride, ethylene dichloride, trichloroethane, and chlorobenzene; ethyl acetate, propyl acetate, butyl acetate, ethyl octylate, ε-caprolactone, γ-valerolactone, etc. Ester solvent; methanol, ethanol, isopropyl alcohol, n-butanol,
sec- Alcohol solvents such as butanol, octanol, and ethylene glycol; Ketone solvents such as acetone, methyl ethyl ketone, acetophenone, and acetylacetone; Nitrile solvents such as acetonitrile, adiponitrile, and benzonitrile; ε-caprolactam, propiolactam, butyrolactam, and valero Amide solvents such as lactam, N-methylpyrrolidone, N-ethylpyrrolidone, N-methylformamide, N-ethylformamide, and N,N-dimethylformamide can be mentioned. Among these, ester solvents are particularly preferred. The amount of solvent is preferably 0 to 1000 relative to the monomer.
% by weight, more preferably 0 to 300% by weight. Further, in the present invention, the polymerization temperature is from 0°C to 80°C, preferably from 5°C to 50°C. According to the present invention, since the polymerization system is maintained in a suspended state, the viscosity inside the reactor is low and the temperature can be easily controlled. Additionally, a small amount of surfactant may be added to the reaction system to stabilize the suspended state. The polymers obtained according to the invention contain a high proportion of unsaturated side chains (high content of 1,2-bonds). In addition, the melting point (Tm) of the polymer can be adjusted to 80% by changing the type and amount of organic solvent in which the monomer is dissolved.
It can be controlled from around ℃ to around 200℃. The more organic solvent there is, the lower the Tm will be. In this case, when a hydrocarbon solvent such as toluene or hexane is used, there is little change in Tm, but when a polar solvent such as an ester, alcohol, ketone, nitrile, amide, or sulfoxide is used, the Tm decrease effect is small. big. The present invention further provides BR, SBR, IR, EPR, EPDM,
In addition to synthetic rubbers such as NBR, monomers such as conjugated dienes and carbon disulfide are dissolved in a polymer solution obtained by a known method, and water is added to form a suspension or emulsion state. ) and (B) It is also possible to polymerize by adding a cobalt compound. The polymer obtained by the present invention can be used alone or in combination with other rubbers, synthetic resins, etc., and can be used in tires, footwear, films, sponges, anti-vibration rubber, etc.
In addition to bottles, it is also suitable as a modification material for other rubbers and resins. The present invention will be described below in more detail with reference to Examples, but the present invention is not restricted to these Examples as long as the gist of the present invention is not exceeded. Example 1 (Preparation of catalyst) A Teflon-coated stirring bar and cobalt octylic acid were placed in a 300 ml pressure bottle that had been purged with nitrogen in advance.
After adding 10 ml of 0.20 mol/Ritter cyclohexane solution, the bottle was capped. 0 after adding 3.5ml of butadiene
Place in a water bath at 60°C and add a 0.1 mol/liter isopropyl alcohol solution of sodium borohydride while vigorously rotating the stirring bar.
Added ml. The reacted cobalt solution was reacted for about 15 minutes and used in the polymerization described below. (Polymerization) 200 ml of distilled water was added to a 350 ml pressure bottle, and after bubbling nitrogen for 5 minutes, 17.7 g of butadiene was added and the bottle was capped. To this was added 0.20 mmol of carbon disulfide and 7.4 ml (0.20 mmol of cobalt) of the above-mentioned reacted cobalt solution, and after vigorous shaking, the mixture was placed in a rotating polymerization tank at 20° C. and polymerized for 1 hour. After polymerization, the polymer was collected by filtration using Tetron cloth. It was immersed in a methanol solution in which the anti-aging agent BHT was dissolved and then vacuum-dried at 50°C. The yield was 92%; the 1,2 content of the polymer was 96%; the Tm by DSC ^* was 172°C. ^* DSC: Abbreviation for Differential Scanning Calorimeter. Determined using Dupont Model 900 DSC analyzer. The heating rate was 20°C/min, the sample was 10 mg, and alumina was used as a reference. The microstructure of the polymer was calculated using the Morero method using infrared absorption spectra. Example 2 Using the catalyst prepared in Example 1, polymerization was carried out using a solution of the monomer in ε-caprolactone during polymerization. (Polymerization) Add 200 ml of distilled water to a 350 ml pressure bottle, and after bubbling nitrogen for 5 minutes, ε-caprolactone 1
ml and 17.7 g of butadiene and capped. Add 0.20mM of carbon disulfide and the reacted cobalt solution of Example 1 to this.
7.4 ml was added, polymerization was carried out in the same manner as in Example 1, and post-treatment was carried out. The yield of the polymer is 93%; the 1,2 content of the polymer is
96%; Tm by DSC was 169°C. Example 3 The same procedure as in Example 2 was carried out except that methyl acetate was used instead of ε-caprolactone. The results are shown in Table 1. Example 4 The same procedure as in Example 2 was carried out except that dimethyl fumarate was used instead of ε-caprolactone. The results are shown in Table 1. Example 5 Polymerization was carried out using 15.9 g of butadiene and 2.2 g of isoprene instead of 17.7 g of butadiene in Example 1,
Post-treatment was carried out in the same manner as in Example 1. The yield of polymer was 53% and Tm was 159°C. The 1,2 bond of butadiene units in the polymer was 96%.
Furthermore, when the polymer was made into a film and an infrared absorption analysis was performed, absorption of 3,4 polyisoprene was observed at 890 cm. The lower Tm of the polymer indicates that butadiene and isoprene are copolymerized.

[Table] Comparative Example 1 After adding 200 ml of distilled water to a 350 ml pressure bottle and bubbling with nitrogen for 5 minutes, the monomers and catalyst components were added in the order of addition shown in Table 2 without pre-preparing the catalyst. No polymer was obtained. Table 2 Order of addition of monomers and catalyst components A BD→B→Co→CS ₂ B BD→B→CS ₂ →Co C BD→Co→B→CS ₂ D BD→Co→CS ₂ →B E BD→ CS ₂ →B→Co BD→CS ₂ →Co→B Note BD: Butadiene (17.7g), B: Sodium borohydride (0.72mM), Co: Cobalt octylate (0.24mM) CS ₂ (0.24mM) After each addition, the pressure bottle was shaken vigorously and allowed to stand for about 1 minute. Example 6 In order to further clarify the effects of the present invention, suspension polymerization was carried out using an autoclave with an internal volume of 850 ml. Distilled water in an autoclave with an internal volume of 850ml
Pour 300ml, purge with nitrogen for 10 minutes, and then heat to 5°C.
The mixture was cooled to 150 ml, and 15 ml of ε-caprolactone was added. Furthermore, 26.6 g of butadiene and 0.30 mmol of carbon disulfide were added and stirred vigorously. 11.0 ml of the catalyst (reacted cobalt solution) prepared in Example 1 (as the amount of cobalt)
0.30 mmol) and kept the polymerization temperature at 15 °C.
Polymerization was carried out for minutes. Post-treatment was carried out in the same manner as in Example 1. The results are shown in Table 3. Example 7 The experiment was carried out in Example 6 except that ε-caprolactone was replaced with ethyl acetate. The results are shown in Table 3. Examples 8 and 9 Example 7 was carried out by varying the amount of methyl acetate and the amount of the prepared catalyst. Example 10 The same procedure as in Example 9 was carried out by replacing methyl acetate with methanol. The results are shown in Table 3. Example 11 The amount of methyl acetate in Example 7 was changed to 30 ml, and polymerization was carried out without purging the autoclave with nitrogen. The polymer was obtained with a yield of 35%. This also shows that the catalyst of the present invention is strong not only against water but also against air. Example 12 After putting 300 ml of distilled water into an autoclave with an internal volume of 850 ml and performing a nitrogen purge for 10 minutes, it was cooled to 5°C, and 23.9 g of butadiene, 3.3 g of isoprene, and 0.21 mmol of carbon disulfide were added and stirred vigorously. 11.0 ml (cobalt amount: 0.30 mmol) of the catalyst prepared in Example 1 was added, the polymerization temperature was maintained at 15° C., polymerization was carried out for 20 minutes, and post-treatment was carried out in the same manner as in Example 1.

【table】 [Brief explanation of drawings]

FIG. 1 is a flowchart showing the steps for preparing a catalyst used in the method of the present invention.

Claims (1)

[Claims] 1. A cobalt compound (A) and a hydrogenated metal compound (B) of a metal from Groups 1 to 3 of the periodic table are brought into contact in advance in the presence of a conjugated diene in an amount of 1 to 100 times the mole of (A). A diene polymer characterized in that a conjugated diene is polymerized in an aqueous system in the presence of a catalyst system in which at least one selected from carbon disulfide, phenylisothiocyanate and a xanthogen compound coexists with the obtained catalyst. Production method.