JPS6072941A - rubber composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a comb composition with improved rolling resistance, wet skid resistance, fracture properties and processability.

In recent years, due to the demand for lower fuel consumption and driving safety for automobiles, rubber materials with low rolling friction resistance and high wet skid resistance are being used as rubber materials for automobile tire treads. Styrene-butadiene copolymers containing one branched polymer have been proposed. .

For example, JP-A-57-559121 JP-A-57-874
07 etc. Since these styrene-butadiene copolymers are produced by cuticle polymerization, the molecular weight distribution is generally narrow with Mw//Mn less than 2, and therefore, the molecular weight distribution is narrow. - The processability of the compounded rubber, such as the ability to mix it with the rubber compounding components using a direct mixer and the ability to wrap it around a roll, is poor, and its tensile properties are still insufficient. When a small amount of other materials such as natural rubber or polyisozolene vinyl is blended in order to improve processability, there is a drawback that the impact resilience and tensile strength are reduced.

As a result of intensive research, the present inventors have found that a branched styrene-butadiene copolymer in which the bond in the branched portion is a tin-carbon bond has a molecular weight distribution curve with substantially a single peak and a broad molecular weight distribution. A rubber composition containing at least 50% by weight of a continuously polymerized styrene-citadiene copolymer with a high vinyl bond content has good processability, tensile properties, impact resilience, sea urchin, and toss skid resistance. Even a small amount of blended isogrene rubber has rebound resilience.

The present invention was achieved by discovering that the rubber material is suitable as a rubber material for tire treads without impairing tensile strength.

According to the invention, the coupling of an active styrene-butadiene copolymer anion obtained by polymerization with an organolithium compound initiator in a hydrocarbon solvent in the presence of an ether or a tertiary amine with a tin halide compound. A random styrene-butadiene copolymer obtained by the reaction, wherein the peak of the molecular weight distribution curve of the core copolymer measured by a molecular weight miniaturization chromatography is substantially one peak, M, /M, is 2 to 2.8%, Gi) the vinyl bond content of the butadiene moiety of the copolymer is 30 to 90%, and QiD the bound styrene content of the copolymer is 5 to 40% by weight. (ψ random styrene-butadiene in which the proportion of branched polymers bonded by tin-carbon bonds is at least 20% by weight, and υ the Mooney viscosity (ML, +4) of the copolymer is from 40 to 150); There is provided a rubber composition comprising at least 50% by weight of the total rubber component of the copolymer.

It is important that the copolymer in the present invention contains at least 20% by weight, preferably 30% by weight or more of a branched styrene-butadiene copolymer whose branched portions have tin-carbon bonds. If it is less than 20, the rebound resilience is poor.

The tin-carbon bond is preferably a mixture of tin-butadienyl and tin-styryl bonds from the viewpoint of the effects of the present invention and productivity.

In the case of a branched styrene-butadiene copolymer in which the bond in the branched portion is a metal-carbon bond other than tin, such as a silicon-carbon bond or a carbon-carbon bond, the branched styrene-butadiene copolymer with a tin-carbon bond of the present invention Compared to the ZEN copolymer, the Mooney viscosity of the cross-wire blend is higher, resulting in poor processability and lower impact resilience of the vulcanizate.

Molecular weight distribution Mw of the styrene-butadiene copolymer of the present invention
/MH is 2 or more and 2.8 or less; when My/Mn is less than 2, processability such as roll and calendar winding properties of the carbon kneaded material is poor; on the other hand, when M and /Mn exceed 2.8, the molecular weight Since the amount of low molecular weight components of 10,000 or less increases, the impact resilience decreases.

The amount of bound styrene in the above copolymer is from 5 to 40% by weight, and if it is less than 1% by weight, it will be poor in terms of wet skid properties and tensile properties, while if it exceeds 40% by weight, it will be poor in rebound.

It is also necessary that the bound styrene be distributed substantially randomly in the copolymer; 1. M.Kolthof
The oxidative decomposition method of f et al. [: J, Polymey Sei
, Vol.

The block polystyrene content, determined according to IP 429 (1946)], is not more than 20% by weight in bound styrene. If the content of pro- and polystyrene in the bonded styrene exceeds 20 parts by weight, it is unfavorable in terms of impact resilience.

The amount of vinyl in the above copolymer is 30 or more, preferably 4
If it is 0 eIb or more and 90 inches or less and less than 30 inches, it is not preferable in terms of wet skid resistance characteristics.

The Mooney viscosity of the above styrene-butadiene copolymer is 4
It is 0-150. If the Mooney viscosity is less than 40, it is unfavorable in terms of rebound resilience, and if it exceeds 150, it is unfavorable in terms of processability.

The styrene-butanoene copolymer of the present invention can be produced by the following various methods. One method is to carry out continuous polymerization by continuously introducing monomers, solvents, vinyl quantity regulators, and initiators into two or more tower houses or seed reactors connected in series, and then to carry out continuous polymerization. This is a method in which a tin halide compound is added at the inlet and a coupling reaction is performed to obtain a polymer containing a branched polymer with a wide molecular weight distribution.In the above method, diethyl ether, orthodimethoxybenzene is used as a preferable vinyl content regulator. , tetrahydrofuran, dimethoxyethane, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, NN
Ethers or tertiary amines such as N'N'-tetramethylethylenediamine, N-methylmorpholine, pyridine, sopiperidinoethane are used. Hydrocarbon solvents such as hexane, hegetane, cyclohexane, and benzene are used as solvents.

As an initiator, n-butyllithium, 5ee-butyllithium, t-butyllithium, 1,4-dilithiobutane,
Organolithium compounds such as 1,5-silithiopentane are used. Polymerization is carried out at -20 to 150°C, preferably 0 to 1
It is carried out at isothermal or elevated temperatures in the range of 20°C.

Power,! The cylinder reaction is carried out in the range of 0.1 to 2.0 equivalents of the tin halide compound per 1 gram equivalent of the temperature probe in the range of 0 to 120°C.

As a cassylinder agent, tetrachlorotin, trichloromethyltin, tetrabromtin, tribrommethyltin,
Tin halide compounds such as bis()IJ dichlorotanyl)ethane are used.

Rubbers to be blended with the styrene-butadiene copolymer of the present invention include natural dem, high-cis 1,4 polyimprene rubber polymerized with a Tig 2-type catalyst or an organolithium catalyst, and emulsion-polymerized styrene-citadiene copolymer rubber. , styrene-butadiene copolymer rubber polymerized with an organolithium catalyst (this may have a branched portion, like the styrene-citadiene copolymer of the present invention, or it may not have a branched portion) (It may be linear), high 7 s 1.4 polybutadiene polymerized with a Ziegler type catalyst, low cis I liptadiene polymerized with an organolithium catalyst, etc. are used. These natural rubbers and synthetic rubbers are used alone or in combination of two or more in an amount of 50% by weight or less in the total rubber component of the composition. If it exceeds 50% by weight, it is not preferable in terms of wet skidding.

In the case of blends with natural rubber or polyisogrene rubber,
From the viewpoint of tensile strength and rebound resilience, it is preferable that the content is 10% by weight or more.

The rubber composition of the present invention comprises gross oil, carden black, its brightening agent, antioxidant, antiozonant, zinc white, stearic acid, and vulcanization accelerator.

It is used in combination with vulcanizing agents, etc.

The vulcanized product of the rubber composition of the present invention takes advantage of the above-mentioned characteristics and can be used for tire applications such as tire treads and carcass, belts, anti-vibration rubber, industrial products and the like.

The present invention will be explained below with reference to Examples, but the present invention is not limited by these Examples.In Example 0, bonded styrene was measured by an infrared method using a calibration curve of absorption due to phenyl groups at 699 cm2.

The microstructure of the polybutadiene moiety was determined using an infrared method (Mogo/Mn
and the proportion of branched polymer (a) is LALLS (LowA
ng@Lat@r Light Scattering
) The weight was measured using a GPC (repermeability chromatograph) equipped with a detector. The GpC column was 78 and Gel G7000) i3. manufactured by Toyo Noda. G6000H3
, G5000H3゜G4000)13 and a precolumn, and measured at room temperature using hydrofuran as a carrier solvent. The proportion of O-branched polymer calculated from 4 was determined as follows.

That is, the polymer is measured by GPC-LALLS, and this is defined as iw@Next, 2 g of stearic acid is added to 100 g of the polymer, and the nip width is 1.4 mm with a 9-inch roll at 130°C. After masticating for a minute, My was measured in the same manner and this was defined as My2. The proportion of the branched polymer was determined by the following formula.

The rebound resilience was measured at 70° C. so that the rolling of the tire was an indicator of the friction resistance. A Dunlop trypsometer was used as the measuring device. Tensile properties were measured in accordance with JIS K6301.

Wet skiing and de resistance were measured using a British Stanley skid tester on a wet indoor asphalt road surface (25℃).
It was measured with It is indicated by an index with Comparative Example 1 set as 100.

Example 1 Two polymerization reactors with a capacity of 101 and equipped with a stirrer and a jacket were connected in series and maintained at 50°C, and the first reactor was charged with 26 ml of 1,3-butadiene containing 40 ppm of 1,2-butadiene. .09/min, styrene 9, OII
/min, cyclohexa717517m1n',
Polymerization was carried out by continuously feeding 0.075 g of n-butyllithium per 1001 monomers using a metering pump at a rate of 0.551/min of tetrahydrofluff.

After reaching a steady state, 1/6 mole of tetrachlorotin is added to n-butyllithium at the inlet of the second reactor, and a coupling reaction is carried out in the second reactor at 50°C. was carried out.

After adding 0.5 g of 2,6-ditertiary-butyl-p-cresol per 100 g of polymer to the polymer solution, the solvent was removed by steam stripping, and the mixture was dried with a hot roll at 110°C.

Example 2.3, Comparative Example 3 The rubber of Example 1 and natural rubber (R8SΦ3) were blended according to the blending ratio shown in Table 2.

Example 4 Three polymerization reactors each having a capacity of 101 and having a stirrer and a jacket were connected in series and maintained at 50°C, and the first reactor was charged with 1.3-butadiene containing 40 ppm of 1.2-butadiene. 17.1 g/min, styrene 5,9 J
7/mln + cyclohexane 189 I! /min
, tetrahydrofuran at a rate of 2.8 II/min and n-butyllithium in an amount of 0.07711 per 100 I of monomer were continuously fed using a metering pump for polymerization. After reaching a steady state, 1/6 mole of tetrachlorotin is added to n-butyllithium at the inlet of the third reactor, and a coupling reaction is carried out in the third reactor at 50°C. ◎ Example 5 Gafu of Example 4 and natural rubber (R8S+3) were blended at the time of kneading according to the blending ratio shown in Table 2.

Comparative Example 1 In a 5-hole polymerization reactor with a stirrer and a jacket, 1,2
- 1,3-butadiene 3 containing 20 ppm of butadiene
70Ii, styrene 125.9. Cyclohexane 2,2
Prepare 50g, tetrahydrofuran 6, 75.9 30
After the mixture was heated to a temperature of 0.3° C., 0.32 ON of n-butyllithium was added and polymerization was carried out under adiabatic conditions. Immediately after the polymerization temperature stopped increasing, 1,3-butadiene 59 was added, and after 5 minutes, tetrachlorotin was added to n-butyllithium by IA.
A molar amount was added and the coupling reaction was carried out for 20 minutes.

Comparative Example 2 The rubber of Comparative Example 1 and natural rubber (R8S+3) were blended at the blending ratio shown in Table 2 during kneading.

Comparative Example 4 Using the recipe of Example 1, the amount of 3 groups was changed to 1 as in Example 4.
O Comparative Example 5 was polymerized in the same manner as in Example 1, except that the mixture was returned to the first reactor, the residue was fed to the third reactor, and tetrachlorotin was added at the inlet of the third reactor. 1 to monomer 10011 of n-butyllithium
The same procedure as in Example 1 was conducted except that 0.068& was used for n-butyllithium and 1/20 mole of tetrachlorotin was used for n-butyllithium.

Comparative Example 6 The same procedure as in Example 1 was conducted except that 76 mol of tetrachlorosilicon was used relative to n-butyllithium.

Comparative Example 7 The same procedure as Example 1 was carried out except that 0.35j' of tetrahydrofuran was used in Example 1. Comparative Example 8 In Example 1, 1,3-butadiene was fed at 35 F/ml, and styrene was fed. Monomer 1
The same procedure as in Example 1 was conducted except for the feed size of 0.07ON of n-butyllithium to 0.0019.

Table 1 Polymer to.

HAF car? 5゜Zinc white 3 Stearic acid 1 Vulcanization accelerator Ns* Sulfur 1.75 * N-tert-7'thyl-2-benzothiacylsulfenamide Note) Examples 2, 3.5 and Comparative Example 2, In No. 3, the above polymer 109 is a blend polymer.

Claims (1)

[Claims] A cup of an active styrene-butadiene copolymer anion obtained by continuous polymerization using an organolithium compound initiator in a hydrocarbon solvent in the presence of an ether or a tertiary amine and a tin halide compound. A random styrene-butadiene copolymer obtained by a ring reaction, comprising: (1) group permeation chromatography of the copolymer;
The peak of the molecular weight distribution curve according to 7 is substantially one peak, and the MW/Mn is 2 to 2.8 (1), and the vinyl 8 content of the butadiene portion of the copolymer is 30 to 90%. , OID the bound styrene content of the copolymer is from 5 to 40% by weight, (ψ the proportion of branched polymers bound by tin-carbon bonds is at least 20% by weight, M the copolymer A rubber composition comprising at least 50% by weight of a random styrene-butadiene copolymer having a Mooney viscosity (ML) of 40 to 150.