JPH059228A - Production of polybutadiene rubber - Google Patents

Abstract

PURPOSE:To obtain a polybutadiene undergoing a small die swell without detriment to abrasion resistance, high resiliency and low heat buildup inherent in the rubber during extrusion of its blend with a natural rubber and excellent in the properties of a vulcanizate by using a specified catalyst. CONSTITUTION:A polybutadiene rubber having a cis-1,4 bond content of 94% or above and a weight-average molecular weight to number-average molecular weight (Mw/Mn) ratio of 3.5 or below as determined by gel permeation chromatography is obtained by polymerizing 1,3-butadiene in an inert organic solvent in the presence of a catalyst consisting mainly of a compound (a) of a metal of group VIII of the periodic table, a boron halide compound (b), a trialkylaluminum (c), a dialkylaluminum (d) and an alcohol (e) and having a (c) to (d) molar ratio of 10/90-90/10 and an (e) to [(c)+(d)] molar ratio of 0.2-2.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polybutadiene rubber excellent in processability and physical properties, and more specifically, to a polybutadiene rubber exhibiting excellent processability and excellent physical properties when blended with a natural rubber. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, polybutadiene rubber has been used for tires by blending it with natural rubber, taking advantage of its properties such as abrasion resistance, high impact resilience, low temperature characteristics, bending resistance and low heat buildup. Among them, high cis-1,4-polybutadiene rubber having a high cis-1,4 content (hereinafter sometimes referred to as "high cis polybutadiene rubber") is cis-based in terms of abrasion resistance, high impact resilience, and low heat buildup. Superior to low-cis polybutadiene rubber with low 1,4 content. In particular, the high-cis polybutadiene rubber produced using a nickel-based catalyst is superior in roll winding property to other cobalt catalyst systems and titanium catalyst systems, but further improvement in extrusion processability is required. ..

As a method for reducing the die swell of extrusion processability, a polybutadiene rubber in which crystals of syndiotactic-1,2-polybutadiene are dispersed in high cis polybutadiene rubber has been proposed (Japanese Patent Publication No. 63-63). 1355, Japanese Patent Publication No. 55-17059, Japanese Patent Publication No. 64-2422, Japanese Patent Laid-Open No. 3-456.
09 publication). However, this polybutadiene rubber has a drawback that it has a low impact resilience because it contains a crystalline component as compared with a normal high-cis polybutadiene rubber, and it is not sufficient in tire performance.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. By using a specific catalyst, the abrasion resistance characteristic of polybutadiene rubber having a high cis-1,4 content is obtained. It is an object of the present invention to provide a method for producing a polybutadiene rubber which has a small die swell at the time of extrusion when used in a blend with a natural rubber and has excellent vulcanized physical properties while maintaining the properties, high impact resilience and low heat buildup.

[0005]

In the present invention, 1,3-butadiene is added to (a) a metal compound of Group VIII of the periodic table, (b).
Boron halide compound, (c) trialkylaluminum, (d) dialkylaluminum hydride and (e) alcohol as main components, and (c) / (d)
The component (molar ratio) is 10/90 to 90/10, and the component (e) component / [(c) + (d)] component (molar ratio) is 0.
The cis-containing polybutadiene rubber obtained by polymerizing in an inert organic solvent using a catalyst of 2 to 2.0
The present invention provides a method for producing a polybutadiene rubber, wherein the 1,4 content is 94% or more and the weight average molecular weight / number average molecular weight measured by gel permeation chromatography is 3.5 or less.

The (a) Group VIII metal compounds used in the catalyst of the present invention include nickel, cobalt,
Examples thereof include iron, platinum, palladium, osmium, and indium compounds. Specifically, they are organic nickel compounds soluble in an inert organic solvent, and nickel organic acid salts are typical. (A) Specific examples of the Group VIII metal compound of the periodic table include organic acid salts such as nickel naphthenate, nickel formate, nickel octenoate, nickel stearate, nickel citrate, nickel benzoate, and nickel toluate. Examples thereof include organic complex compounds such as nickel acetylacetone and nickel salts of alkylbenzene sulfonic acid. Among these, preferred (a) Group VIII metal compounds of the periodic table include nickel naphthenate, nickel octenoate, and nickel stearate.

The (b) boron halide compound includes boron trifluoride, boron trichloride and other boron halides, boron trifluoride ethyl etherate, boron trifluoride butyl etherate and other boron trifluoride. A boron halide complex compound such as etherate is used. Among these, boron trifluoride and boron trifluoride etherate are particularly preferable.
Furthermore, (c) trialkylaluminum includes trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trihexylaluminum and the like. Furthermore, examples of the (d) dialkylaluminum hydride include diethylaluminum hydride, diisopropylaluminum hydride, diisobutylaluminum hydride and the like. Furthermore, examples of the alcohol (e) include methanol, ethanol, n-propanol, isopropanol, isobutanol, t-butanol, n-hexanol, n-octanol, and 2-ethylhexanol.

The amount of the catalyst used in the present invention is 100 g of 1,3-butadiene, and (a) the metal compound of Group VIII of the periodic table is 0.0
It is about 1 to 1 mmol, preferably about 0.02 to 0.5 mmol. If it is less than 0.02 mmol, the polymerization reaction may not be initiated, while if it exceeds 1 mmol, a high molecular weight product may not be obtained, which is not preferable. Also,
(B) The amount of the boron halide compound used is 0.05 to
It is about 20 mmol, preferably about 0.2 to 10 mmol. Further, the amount of the (c) trialkylaluminum used is preferably about 0.05 to 10 mmol, preferably about 0.2 to 5 mmol. Further, the amount of the (d) dialkylaluminum hydride used is 0.1 to
It is about 10 mmol, preferably about 0.2 to 5 mmol. Furthermore, the amount of (e) alcohol used is 0.02 to
It is about 40 mmol, preferably about 0.1 to 10 mmol. If it is less than 0.02 mmol, Mw / Mn may increase, while if it exceeds 40 mmol, the polymerization reaction may not start, which is not preferable.

The catalyst used in the present invention includes the above (a) to
It is composed of component (e), and in particular, component (c) / component (d) (molar ratio) is 10/90 to 90/10, and component (e) / [(c) + (d)] component (molar ratio). ) Is 0.2-2.
Must be in the 0 range. If the component (c) / (d) (molar ratio) is less than 10/90, Mw / Mn may increase, whereas if it exceeds 90/10, the polymerization reaction may not start, which is not preferable. The molar ratio of the components (c) / (d) is preferably 15/85 to 85/15. Further, when the (e) component / [(c) + (d)] component (molar ratio) is less than 0.2, Mw / Mn becomes large, resulting in large die swell, which is not preferable, while when it exceeds 2.0. However, the polymerization activity is lowered, which is not preferable. (E) component /
The [(c) + (d)] component (molar ratio) is preferably 0.
2 to 1.5.

The catalyst used in the present invention comprises the catalyst components in any order, preferably [(d) → (c) → (b) →
(A)] → (e), [(e) → (d) → (c)] →
(B) → (a), {[(c) + (d)] → (b) →
(A)} → (e), {(d) → (c) → (b) →
[(A) + (e)]} or {[(c) + (d)]
It is prepared by mixing in the order of → (b) → [(a) + (e)]}. The catalyst may be prepared by mixing the respective components in advance before contacting it with the 1,3-butadiene of the present invention, or in the presence of 1,3-butadiene in the polymerization reactor. It is also possible to mix and prepare each component.

In the present invention, 1,3-butadiene is polymerized in an inert organic solvent using a catalyst containing the above components (a) to (e) as a main component. The polymerization solvent is an inert organic solvent, such as benzene, toluene, xylene,
Aromatic hydrocarbon solvents such as cumene, n-pentane, n-
Aliphatic hydrocarbon solvents such as hexane and n-butane, alicyclic hydrocarbon solvents such as methylcyclopentane and cyclohexane, methylene chloride, chloroform, carbon tetrachloride, trichloroethylene, perchlorethylene, chlorobenzene, bromobenzene and chloro. Halogenated hydrocarbon solvents such as toluene and mixtures thereof, preferably n-hexane, n-heptane, n-octane, n-decane, cyclohexane, toluene, xylene.

The polymerization temperature is usually from 20 ° C to 100 ° C,
It is preferably 40 to 80 ° C. The polymerization pressure is 0 to 5 atm (gauge pressure). The polymerization reaction may be a batch system or a continuous system. The monomer concentration in the solvent is usually 5
˜50 wt%, preferably 10-35 wt%. Further, in order to produce a polymer, in order not to deactivate the catalyst of the present invention and the polymer, it is necessary to take into consideration the inclusion of a compound having a deactivating action such as oxygen, water or carbon dioxide gas into the polymerization system as much as possible. Is. When the polymerization reaction has proceeded to the desired stage, the reaction mixture is added with alcohol, other polymerization terminator, antioxidant, antioxidant, ultraviolet absorber, etc., and then the produced polymer is separated, washed and dried according to a usual method. Thus, the desired polybutadiene rubber can be obtained.

According to the production method of the present invention, since a specific catalyst is used, a polybutadiene rubber rubber having a high cis-1,4 content and a sharp molecular weight distribution can be obtained. As described above, the polybutadiene rubber obtained by using the catalyst containing the components (a) to (e) as the main components is cis-
The 1,4 content is 94% or more and the Mw / Mn is 3.5 or less. If the cis 1,4 content of the polybutadiene rubber obtained in the present invention is less than 94%, it is not preferable in terms of impact resilience. The cis-1,4 content is preferably 95% or more. This cis-1,4 content can be easily adjusted by controlling the polymerization temperature. Further, in the present invention, Mw / Mn of polybutadiene rubber
When the value exceeds 3.5, the die swell becomes large, which is not preferable. The adjustment of this Mw / Mn is (e) / [(c) +
It can be easily carried out by controlling the molar ratio of the component (d)].

The solution viscosity SV of the polybutadiene rubber
To Mooney viscosity MV (ML _{1 + 4} , 100 ° C), S
V / MV is 4 or more, preferably 4.2 or more, and 4
If it is less than this, the die swell becomes large, which is not preferable. Also,
The molecular weight of the polybutadiene rubber obtained in the present invention can be varied over a wide range, but its polystyrene-equivalent weight average molecular weight is usually 10,000 to
100,000, preferably 40,000-80,000
When it is less than 10,000, it becomes a liquid polymer. On the other hand, when it exceeds 100,000, the processability is poor, excessive torque is applied during kneading with a roll or a Banbury, and the compounded rubber is deteriorated due to high temperature. Moreover, the dispersion of the carbon black becomes poor and the performance of the vulcanized rubber becomes poor, which is not preferable.

Further, when the polybutadiene rubber obtained by the present invention is used as a rubber product for industrial use, its Mooney viscosity (ML _{1 + 4} , 100 ° C.) is usually 20 to 1
If it is less than 20, the physical properties of the vulcanized rubber will be inferior, while if it exceeds 100, the processability will be inferior.

The polybutadiene rubber obtained by the present invention is used alone or blended with other synthetic rubber or natural rubber to be blended as a raw material rubber for use. In particular,
The polybutadiene rubber of the present invention exhibits a remarkable effect of improving extrusion processability when used in a blend with a natural rubber, and polybutadiene rubber / natural rubber (weight ratio) = 30 to 70/70.
A low die swell value is shown at a blend ratio of ˜30.

The blended rubber of the polybutadiene rubber of the present invention and natural rubber and / or synthetic rubber includes a reinforcing agent,
Contains softeners, anti-aging agents, cross-linking agents, cross-linking aids, etc.
Used as a rubber composition. Among them, carbon black, white carbon, talc, calcium carbonate, clay, etc. are used as the reinforcing agent, and naphthenic oil, aroma oil, paraffin oil, etc. are used as the softening agent.
As the anti-aging agent, amine-based and phenol-based anti-aging agents are used, as the cross-linking agent, sulfur, sulfur-containing compounds and the like are used, and as the cross-linking aid, thiazole-based and thiuram-based vulcanization accelerators are used. .. INDUSTRIAL APPLICABILITY The polybutadiene rubber of the present invention can be used in rubber applications where mechanical properties and abrasion resistance are required, such as tires, hoses, belts and various other industrial products.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, parts and% are based on weight unless otherwise specified.
In addition, various measurements in the examples were performed by the following methods.
Mooney viscosity (ML _{1 + 4} , 100 ° C) is a value after 4 minutes after preheating at 100 ° C for 1 minute using L-type rotor using SMV-200 type Mooney machine manufactured by Shimadzu Corporation. Was measured. The cis-1,4 content is from JASCO Corporation,
It measured using the A-2 type infrared spectrophotometer and calculated by the Morello method.

The solution viscosity (SV) is 5.23% toluene solution viscosity at 30 ° C. using a Canon Fenske viscometer.
It was measured at. The molecular weight of polybutadiene is Tosoh Corporation.
Manufactured by HLC-802 Model Gel Permeation Chromatograph. Column: GMHL x 2 Flow rate: 1 ml / sec Sample concentration: 0.02 g / 10 ml Tetrahydrofuran Measurement temperature: 40 ° C Die swell is manufactured by Nippon Synthetic Rubber Co., Ltd. slit slit rheometer at 100 ° C and 500 mm / min. The extrusion rate was calculated from the length and the weight.
The tensile test of the vulcanized rubber was measured according to JIS K6301. For the impact resilience, a value at 50 ° C. was measured by using an impact resilience tester manufactured by Dunlop.

Example 1 In an autoclave having an internal volume of 5 liters, which was replaced with nitrogen,
After 2,750 g of dehydrated and purified toluene was charged and 1.66 ml of 2-ethylhexyl alcohol was charged,
500 g of 1,3-butadiene was charged and the temperature was kept at 25 ° C. On the other hand, 0.51 mmol of nickel naphthenate, 10 mmol of boron trifluoride ethyl etherate, 1.66 mmol of diisobutylaluminum hydride and 1.66 mmol of triethylaluminum were charged into Schlenk substituted with nitrogen and aged at 20 ° C. for 60 minutes. After that, the entire amount was charged into the autoclave to start polymerization. After the initiation of polymerization, adjust the polymerization temperature to 60 ° C and
After stirring for an hour, methanol was added to the polymerization solution to terminate the polymerization.

Then, 2,4-t-butyl- was added to the polymerization solution.
After charging 2.5 g of p-cresol as a toluene solution, the solvent was removed and the product was dried on a hot roll at 120 ° C. Polymer yield 80%, Mooney viscosity 44.5, cis-
1,4 content is 94%, solution viscosity (SV) is 253 cp
s, number average molecular weight (Mn) is 206,000, weight average molecular weight (Mw) is 639,000, Mw / Mn is 3.1.
Met. Using the obtained polymer, a rubber composition was obtained with the following formulation, and the physical properties were evaluated. The results are shown in Tables 1-2.
Shown in.

Examples 2 to 6 Polybutadiene rubber was obtained in the same manner as in Example 1 except that the composition of the polymerization catalyst was changed, and the physical properties of the rubber composition were evaluated using the polybutadiene rubber. The results are shown in Tables 1-2. Comparative Examples 1 to 4 In Example 1, 2-ethylhexyl alcohol and diisobutylaluminum hydride were not used (Comparative Example 1), 2-ethylhexyl alcohol was used in a large amount (Comparative Example 2), and triethylaluminum was not used (Comparative Example). 3), polybutadiene rubber was obtained in the same manner as in Example 1 except that diisobutylaluminum hydride was not used (Comparative Example 4), and the physical properties were evaluated. The results are shown in Tables 3-4.

Formulation (part) Natural rubber (Mooney viscosity = 80) 50 Polybutadiene rubber 50 FEF carbon 50 Aromatic oil 10 Zinc flower No. 1 3 Stearic acid 2 Antigen 3C ^* 3 Sunceller NS ^** 0.8 Sulfur 1.5 *) N-phenyl-N'-isopropyl-p-phenylenediamine **) Nt-butyl-2-benzothiazolyl-sulfenamide

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

INDUSTRIAL APPLICABILITY The polybutadiene rubber obtained by the present invention has excellent vulcanization properties and dimensional stability during extrusion, particularly when blended with natural rubber, and is useful as a tire, especially as a sidewall material.

Claims (1)

Claims: 1. 1,3-butadiene, (a) Group VIII metal compound of the periodic table, (b) boron halide compound,
(C) Trialkylaluminum, (d) dialkylaluminum hydride and (e) alcohol as main components, and (c) / (d) component (molar ratio) is 10/9
0-90 / 10, moreover, component (e) / [(c) +
(D)] The component (molar ratio) is 0.2 to 2.0, and the cis-1,4 content of the resulting polybutadiene rubber is 94% or more by polymerizing in an inert organic solvent. A method for producing a polybutadiene rubber, wherein the weight average molecular weight / number average molecular weight measured by gel permeation chromatography is 3.5 or less.