JPH1129603A - Modified diene-based rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject rubber suitable for vehicle tires by modifying a diene-based rubber of high cis-1,4-structure with a compound composed of a functional group containing chlorosulphenyl or chlorosulfonyl group and nitrogen atom, in such a way to introduce sulfur and nitrogen atoms in the stock rubber. SOLUTION: This rubber is obtained by modifying a diene-based rubber of high cis-1,4-structure, having a Mooney viscosity of 20 to 80 and weight- average molecular weight of 200,000 to 1,000,000, with a compound composed of a functional group containing chlorosulphenyl or chlorosulfonyl group and nitrogen atom, in such a way to introduce sulfur and nitrogen atoms in the stock rubber and increase Mooney viscosity of the stock rubber by at least 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a diene rubber having a high cis-1,4 structure modified by a compound having a nitrogen-containing functional group and a chlorosulfenyl or chlorosulfonyl group. It relates to a modified diene rubber and can be used for automobile tires.

[0002]

2. Description of the Related Art Conventionally, polybutadiene rubber (BR), natural rubber (NR), styrene-butadiene rubber (SBR) and the like have been used as automobile tire rubber. In recent years, there has been an increasing demand for low fuel consumption of automobiles and a demand for running safety on snow and ice, and it has been desired to develop a material having low rolling resistance and a large road grip on snow and ice as an automobile tire tread rubber. Rubber having high rebound resilience (small rolling resistance) such as BR has a low wet skid resistance, and SBR has a high wet skid resistance but a high rolling resistance.

Hitherto, as a method for solving such a problem, many methods have been proposed in which a low cis conjugated diene rubber is chemically modified with a modifier using a lithium catalyst. For example, a method of modifying low cis BR with a benzophenone compound is disclosed in JP-A-58-162604 and JP-A-59-162604.
The rolling resistance of an automobile tire is small, the wet skid resistance is large, and the rebound resilience is improved. A method for modification with an aromatic thioketone is described in U.S. Pat. No. 3,755,269.

Further, Japanese Patent Publication Nos. 6-53766, 6-57769, and 6-78450 disclose a diene rubber having an active alkali metal terminal with a nitroamino compound, a nitro compound, and a nitro compound. It is described that a rubber having excellent rebound resilience and low low-temperature hardness can be obtained by reacting with an alkyl compound. However, low cis BR has insufficient abrasion resistance, and this problem cannot be solved by modification, and SBR has low rebound resilience and does not solve this defect even after modification.

[0005]

Heretofore, there has been little known about a modification method for a rubber having a high cis-1,4 structure content produced by using a cobalt, nickel, titanium, or neodymium catalyst. In view of the above problems, the present invention provides a rubber having a high cis-1,4-structure content by using a compound containing a chlorosulfenyl group or a chlorosulfonyl group in a molecule and a functional group containing a nitrogen element. , A modified diene-based rubber, and by introducing sulfur and nitrogen elements into the modified diene-based rubber, a rubber suitable as an automobile tire tread rubber having good abrasion resistance, rolling resistance and wet skid property is obtained. It is intended to provide.

[0006]

According to the present invention, there is provided a modified diene-based rubber comprising: (a) a diene-based rubber having a repeating unit of 80;
% Or more has a cis-1,4 structure and Mooney viscosity (ML _{1 +} 4,1
(B) a diene rubber having a weight average molecular weight (Mw) of 200,000 to 1,000,000 according to GPC (b) a functional group containing a nitrogen element and a chlorosulfenyl group or A modified diene rubber modified by a compound having a sulfonyl group, wherein (c) the modified diene rubber contains a sulfur element and a nitrogen element, and the Mooney viscosity thereof is increased by one or more as compared with before the modification. It is about. The diene rubber is produced using a cobalt, nickel, titanium or neodymium catalyst system.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the components of the present invention will be specifically described. The diene rubber will be described. A diene rubber is a rubber obtained by polymerizing or copolymerizing a conjugated diene with a cobalt, nickel, titanium, or neodymium catalyst system, and cis-1, 80% or more of the repeating structure.
4-structure. Preferably, 90% or more is cis-1,4.
And more preferably 95% or more of a conjugated diene polymer or copolymer rubber. 80 repeating structures
% Of the diene rubber having a cis-1,4-structure of less than 10% is not preferable since the object of the present invention cannot be achieved because of low rebound resilience. Specific examples of the diene rubber include polybutadiene (BR), polyisoprene (IR), styrene-butadiene rubber (SBR), isoprene-butadiene rubber, and nitrile-butadiene rubber (NBR).
Preferably it is BR. Generally, a commercially produced product may be used, or an appropriately synthesized product may be used.

The modifier will be described. The modifier is a compound having a chlorosulfenyl group (—SCl) or a chlorosulfonyl group (—SO ₂ Cl) in the molecule and a compound having a functional group having a nitrogen element at the same time. Carbamoyl group as a functional group having a nitrogen element,
Nitro, nitroso, amino, methylamino, quinolino, dimethylamino, anilino, acetamido, imino, phenylimino, oxyamino,
Examples include an oximino group, a nitroamino group, a hydrazino group, a diazo group, an azo group, an azoxy group, a hydrazo group, a phenylazo group, and an amidino group. Specific examples of the modifier include chlorosulfenyl compounds such as 2,4-dinitrobenzenesulfenyl chloride, 4-nitrobenzenesulfenyl chloride, 4-nitrobenzenesulfonyl chloride, 2-acetamidobenzenesulfonyl chloride, 1-amino Naphthyl-5
Chlorosulfonyl compounds such as sulfonyl chloride, quinoline sulfonyl chloride, dimethylsulfamoyl chloride, dimethylsulfonyl chloride, and 2,4-dinitrobenzenesulfonyl chloride. These modifiers may be used alone or in combination of two or more.

A method for modifying a diene rubber will be described. The modification of the diene rubber may be carried out by contacting and modifying the above-described modifier with the diene rubber in an organic solvent, or by adding the modifier directly to the polymerization solution of the diene rubber. Can be. As another method, it is also possible to directly knead and modify with an extrusion kneader or the like. When the modification reaction rate is low, aluminum halide or alkyl halide can be used as a catalyst to increase the reaction rate. Examples of the aluminum halide include aluminum chloride, aluminum bromide, and aluminum iodide. Examples of the alkyl halide include ethyl bromide, ethyl iodide, butyl chloride, butyl bromide, and butyl iodide.

As the organic solvent used in the modification reaction, any organic solvent which does not react with the diene rubber can be used. Usually the same as the polymerization solvent, such as aromatic hydrocarbons such as benzene, chlorobenzene, toluene and xylene, aliphatic hydrocarbons such as n-heptane, n-hexane, n-pentane and n-octane, cyclohexane, methylcyclohexane , Tetralin, decalin and the like are preferably used. Further, methylene chloride, tetrahydrofuran and the like can be used.

The denaturation temperature in the solution is preferably in the range of 0 to 100 ° C, more preferably in the range of room temperature to 70 ° C. If the temperature is too low, the progress of the modification reaction is slow, and if the temperature is too high, the polymer gels, which is not preferable. The denaturation time in the solution is not particularly limited, but is usually preferably in the range of 0.5 to 6 hours. If the denaturation time is too short, the reaction does not proceed sufficiently, and if the time is too long, the polymer may gel, which is not preferable.

The concentration at which the diene rubber is dissolved in the solvent is in a preferable state in order to smoothly carry out the modification reaction. The amount of diene rubber is 5 to 500 g per liter of solvent,
Preferably 20 to 200 g, more preferably 30 to 10 g.
0 g.

The amount of the modifier used will be described. The amount of the modifier used is 0.01 to 1 with respect to 100 g of the diene rubber.
It is 50 mmol, preferably 1 to 100 mmol, more preferably 3 to 50 mmol. If the amount used is small, the amount of nitrogen element and sulfur element introduced into the modified diene rubber becomes small, and the modification effect is small. If the amount is too large, the unreacted modifier remains in the modified diene-based rubber, and the removal thereof is troublesome, which is not preferable. In the modification reaction, a catalyst can be used depending on the type of the modifying agent. At this time, the amount of the catalyst used is 0.01 g per 100 g of the diene rubber.
-100 mmol, preferably 0.05-50 mmol, more preferably 0.08-20 mmol.

The modified diene rubber obtained according to the present invention may be blended alone or blended with other synthetic rubbers or natural rubbers, if necessary, oil-extended with a process oil, and then a filler such as carbon black. Vulcanization by adding a vulcanizing agent, vulcanization accelerator and other usual compounding agents,
Used for rubber applications requiring mechanical properties and abrasion resistance such as belts and various other industrial products. It can also be used as a modifier for plastics.

[0015]

EXAMPLES The present invention will now be described specifically with reference to examples, but these do not limit the purpose of the present invention. Mooney viscosities (ML _{1 + 4} , 100 ° C.) of the rubbery polymers obtained in Examples and Comparative Examples, cis-1,4
-Structure, molecular weight and molecular weight distribution, nitrogen content and sulfur content were measured as follows. Mooney viscosity (ML _{1 + 4} , 100 ° C) : JIS K630
0 according to Shimadzu's Mooney viscometer (SMV-20
0) was preheated at 100 ° C. for 1 minute and measured for 4 minutes and expressed as the Mooney viscosity of the rubber (ML _{1 + 4} , 100 ° C.). Cis-1,4-structure amount : The microstructure of the polymer was measured by infrared absorption spectrum analysis using a 0.4 wt% carbon disulfide solution to calculate the cis-1,4-structure amount. Molecular weight and molecular weight distribution : Weight average molecular weight (Mw) calculated using a calibration curve obtained from a molecular weight distribution curve of gel permeation chromatography (manufactured by Tosoh Corporation, GPC) at a temperature of 40 ° C. using polystyrene as a standard substance and tetrahydrofuran as a solvent. And the number average molecular weight (Mn) is determined, and the weight average molecular weight (Mw) and M
w / Mn. Nitrogen content : Quantified by the Kjeldahl method according to JIS K0102. Sulfur content : Approximately 10 mg of a polymer was precisely weighed as a sample, and sulfur oxide generated by burning at a temperature of 300 to 1,000 ° C. by a combustion tube combustion method was supplemented with a sodium carbonate / H ₂ O ₂ absorbing solution. Thereafter, a calibration curve was prepared in advance using a standard solution having a known sulfur content using ion chromatography (manufactured by Nippon Dionex, AQ type), and quantification was performed. Rebound: Use the Dunlop triple-Soviet meter 23
It was measured at ° C. and shown in%. Hardness : Measured at -20 ° C according to JIS K6301. tan δ : Rheometrics viscoelasticity meter (RS
(A2 type) at a temperature of 70 ° C. and a frequency of 10 Hz. Wet skid resistance : Measured according to ASTM E303 using a portable skid resistance meter manufactured by Stanley. Indices of grip characteristics (driving performance, braking performance and steering performance) on wet road surfaces indicate that the larger the value, the better.

EXAMPLE 1 A polybutadiene rubber (UBE, Ube Industries, Ltd., manufactured by Ube Industries, Ltd.) was prepared in a 2-liter glass separable flask equipped with a stirrer and a temperature controller.
EPOL-340L, ML _{1 + 4} , 100 ° C = 34, cis-
1,4-structure = 98%, weight average molecular weight by GPC =
510,000, molecular weight distribution Mw / Mn = 2.4) 13
0 g and 1.2 liters of toluene are added, and the mixture is stirred at 60 ° C.
And the polybutadiene was completely dissolved. Next, 39 mmol of the modifying agent 2,4-dinitrobenzenesulfenyl chloride previously dissolved in tetrahydrofuran was added, and a denaturing reaction was performed at 60 ° C. for 2 hours. After completion of the reaction, the reaction solution was cooled to room temperature, transferred to a 3 liter flask, and 1.2 liter of methanol was added to precipitate a modified polybutadiene. This precipitation-modified polybutadiene was separated through a 300-mesh wire gauze and used as an antioxidant.
[Methylene-3- (3 ', 5'-di-t-butyl-4'
-Hydroxyphenyl) propionate] methane (Irganox 1010, manufactured by Ciba-Geigy Japan) was charged and kneaded at 1,000 ppm with respect to the polybutadiene rubber, followed by vacuum drying at 100 ° C. for 1 hour to obtain a modified polybutadiene rubber. Purification of modified polybutadiene rubber ; 10 g of this modified polybutadiene rubber was added to 300 ml of toluene and stirred at room temperature to dissolve completely, and then 300 ml of methanol was added to this solution to precipitate the modified rubber and to obtain a solid content of 250 ml. Filtration and separation were performed using a mesh wire mesh. This operation was repeated again to remove the denaturing agent, and the purified modified polybutadiene rubber was dried under vacuum at 100 ° C. for 1 hour and evaluated as a sample for analysis. The modified polymers obtained in Examples and Comparative Examples were also subjected to the same purification. ML _{1 + 4} ,
100 DEG C. = 53, nitrogen content = 3,760 ppm, sulfur content = 5,600 ppm, Mw = 993,000, molecular weight distribution Mw / Mn = 4.04. [Example 2]

A modified polybutadiene rubber was obtained in the same manner as in Example 1 except that the amount of the modifier was changed to 26 mmol. This modified polybutadiene rubber is ML _{1 + 4} , 100 ° C
= 51, nitrogen content = 2,730 ppm, sulfur content =
3,000 ppm, Mw = 1,014,600, molecular weight distribution Mw / Mn = 4.24.

Example 3 A modified polybutadiene rubber was obtained in the same manner as in Example 1 except that the amount of the modifier was changed to 13 mmol. This modified polybutadiene rubber is ML
_{1 + 4} , 100 ℃ = 47, nitrogen content = 1,730ppm,
Sulfur content = 1,700 ppm, Mw = 936,70
0, molecular weight distribution Mw / Mn = 3.54.

Example 4 A modified polybutadiene rubber was obtained in the same manner as in Example 1 except that 52 mmol of dimethylsulfamoyl chloride was used instead of 2,4-dinitrobenzenesulfenyl chloride as a modifier. This modified polybutadiene rubber has ML _{1 + 4} , 100 ° C. = 35, nitrogen content = 55 ppm, sulfur content = 50 ppm, Mw
= 675,200, molecular weight distribution Mw / Mn = 2.69.

Example 5 A modified polybutadiene rubber was obtained in the same manner as in Example 4 except that 52 mmol of dimethylsulfamoyl chloride as a modifier was used and 26 mmol of aluminum chloride was used as a catalyst for the modification reaction. This modified polybutadiene rubber has ML _{1 + 4} , 100 ° C. = 45, nitrogen content = 45 ppm, sulfur content = 40 ppm, Mw
= 625,700, molecular weight distribution Mw / Mn = 2.36.

Example 6 1,040 ml of cyclohexane and 1,3-butadiene 5 were placed in a 3 liter autoclave equipped with a temperature controller and a stirrer in which the inside was replaced with nitrogen.
20 ml was charged and heated to 50 ° C. with stirring, and 3.9 mmol of diisobutylaluminum hydride in a heptane solution, 0.5 mmol of neodymium versatate in a heptane solution, and diethylaluminum monochloride in a heptane solution were added. 3 mmol was continuously added in sequence, and polymerization was carried out at 50 ° C. for 1 hour. After completion of the polymerization, 5.2 ml of a tetrahydrofuran solution containing 5 ml of methanol and 26 mmol of 2,4-dinitrobenzenesulfenyl chloride was introduced into the autoclave, and a denaturation reaction was performed at 50 ° C. for 1 hour. Next, ethanol containing 0.5 g of Irganox 1010 /
1300 ml of a mixed solution of acetone was added to precipitate and recover the modified polybutadiene rubber. Vacuum drying was performed at 60 ° C. for 8 hours to obtain a modified polybutadiene rubber. This modified polybutadiene rubber has ML _{1 + 4} , 100 ° C. = 55, nitrogen content = 2,960 ppm, sulfur content = 3,080.
ppm, Mw = 1,000,000, molecular weight distribution Mw /
Mn = 6.03.

Example 7 In the same manner as in Example 6, 1040 ml of toluene and 520 ml of 1,3-butadiene were charged and maintained at 25 ° C. with stirring. Next, 0.047 mmol of nickel naphthenate, 0.52 mmol of boron trifluoride ethyl etherate and 0.44 mmol of triethylaluminum were previously placed in an aging flask at room temperature.
The mixture was mixed for 10 minutes to carry out an aging reaction. The whole amount of the aging solution was introduced, the temperature was raised to 60 ° C., and polymerization was performed for 2 hours. After the polymerization, 13 ml of methanol and 2,
Then, 5.2 ml of a tetrahydrofuran solution containing 26 mmol of 4-dinitrobenzenesulfenyl chloride was introduced, and a denaturation reaction was performed at 60 ° C. for 1 hour. Then I
1300 ml of a mixed solution of ethanol / acetone containing 0.5 g of rganox1010 was added to precipitate and recover the modified polybutadiene rubber. Vacuum drying was performed at 60 ° C. for 8 hours to obtain a modified polybutadiene rubber. This modified polybutadiene rubber has ML _{1 + 4} , 100 ° C. = 42, nitrogen content = 2,450 ppm, sulfur content = 2,580 pp
m, Mw = 614,000, molecular weight distribution Mw / Mn =
It was 3.90.

Comparative Example 1 A modification reaction was carried out in the same manner as in Example 1 except that 26 mmol of dimethylcarbamoyl chloride was used as a modifier. The rubbery polymer obtained had ML _{1 + 4} , 100 ° C. = 34, nitrogen content = 10 ppm, sulfur content = not detected, Mw = 528,000, molecular weight distribution Mw / Mn = 2.40.

Comparative Example 2 Example 1 was repeated except that 19.5 mmol of 2,4-diaminobenzophenone was used as a modifier.
A denaturation reaction was performed in the same manner as described above. The rubbery polymer obtained was ML _{1 + 4} , 100 ° C. = 34, nitrogen content = 15 pp.
m, sulfur content = not detected, Mw = 618,000,
The molecular weight distribution Mw / Mn was 2.40.

Comparative Example 3 The polybutadiene rubber used in Example 1 was compounded as shown in Table 1 to prepare a rubber composition. Similarly, in Examples 1 to 7 and Comparative Examples 1 and 2, rubber compositions were prepared by blending as shown in Table 1. The obtained mixture was press-vulcanized at 150 ° C. for 12 minutes, and the physical properties of the vulcanized product were tan δ as loss tangents of rebound resilience, hardness and dynamic viscoelastic modulus, and wet skid resistance (Comparative Example 1 was taken as 100). Table 2 shows the measured values.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

Since the modified diene rubber of the present invention contains a nitrogen element and is modified with a chlorosulfenyl (or chlorosulfonyl) compound as a functional group, nitrogen and sulfur elements are contained in the modified diene rubber molecule. At the same time, the rebound resilience is improved, and the wet skid resistance is also improved.

Continued on the front page (72) Inventor Noriko Yagi 2-1-1 Tsutsui-cho, Chuo-ku, Kobe-shi, Hyogo Sumitomo Rubber Industries, Ltd.

Claims (2)

[Claims] In a modified diene rubber, (a) 80% or more of the repeating units of the diene rubber have a cis-1,4 structure and a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 20 to 80;
Weight average molecular weight (Mw) of 200,000-PC
1,000,000 diene rubber is modified with (b) a compound having a functional group having a nitrogen element and a chlorosulfenyl group or a chlorosulfonyl group, and (c)
A modified diene rubber wherein the modified diene rubber which has been modified and has a sulfur element and a nitrogen element has a Mooney viscosity increased by one or more as compared to before the modification. 2. The diene rubber according to claim 1, wherein the diene rubber is cobalt,
Manufactured with nickel, titanium or neodymium catalysts.