JPH08120119A - Rubber composition for improved tire tread - Google Patents

Abstract

PURPOSE: To obtain a rubber composition for tire tread useful as a material for automobile tire requiring excellent processability, grip, high-speed durability and high-speed performances. CONSTITUTION: This rubber composition for tire tread is obtained by blending 100 pts.wt. of selectively and partially hydrogenated rubber which is obtained by selectively and partially hydrogenating the double bond of part B so as to make S-B copolymer rubber having a specific weight ratio of bonded S/ bonded B (wherein, S is styrene; B is butadiene) and a prescribed micro structure have 10-60% hydrogenation ratio based on the part B and the ratio of the amount of hydrogenated 1, 2 bond/that of the whole hydrogenated double bonds of 0.6-1.0 and has specific Mooney viscosity and glass transition temperature with 70-200 pts.wt. of prescribed carbon black, 40-100 pts.wt. of an extension oil for rubber and 1-10 pts.wt. of a curing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-like polymer composition, and more particularly to a tire having extremely good grip performance when used for tire tread applications, and having low heat buildup and excellent high-speed durability. It relates to a rubbery polymer composition that provides a tread.

[0002]

2. Description of the Related Art In recent years, with the development of the automobile industry, various performances such as safety, driving stability, economy, habitability, and pollution-free have been improved more than ever before with respect to tires mounted on automobiles. Is desired. In particular, as the number of automobiles traveling at high speed has increased due to the improvement of the traveling ability of automobiles and the maintenance of expressways, and as the motor sports have become widespread, tires traveling at a high speed of, for example, 200 Km / hr or more can be used at high speeds. In addition to improving the braking characteristics, steering stability, and cornering characteristics of the vehicle, high-speed durability is also required, such as prevention of blowout due to heat generation during high-speed driving.

Since the steering performance of a tire is mainly affected by the grip performance of a tire tread, it is necessary to increase the coefficient of friction with the road surface by using a composition having a high hysteresis loss as a tread rubber composition. Is widely practiced. In order to increase the hysteresis loss of the tread rubber composition, a rubber-like polymer having a glass transition temperature (Tg: extrapolation start temperature measured by DSC) higher than that of a normal raw material rubber is used as the raw material rubber used. In addition, a method of blending a large amount of carbon black having a small particle size and a large surface area as compared with a general tire tread composition is widely used.

However, in the method using a raw rubber having a high Tg, the hysteresis loss increases as the Tg of the raw rubber increases, but the compound becomes hard at low temperature and the grip performance of the tire in cold regions of 5 ° C. or lower. There is also a problem that the performance on snow and ice is extremely deteriorated, and the hysteresis loss is high, so the heat generation of the tread compound is also inferior.

On the other hand, the use of carbon black having a small particle size increases the heat generation of the tread compound to increase the rolling resistance, and in extreme cases causes a problem such as blowout of the tire to deteriorate the high speed durability. In addition, since the surface area of such carbon black is extremely large, the interaction with rubber increases, the viscosity of the rubber compound increases, the processability deteriorates, and it is relatively difficult to uniformly disperse the carbon black. Have problems such as.

Therefore, for a tire tread compound which is generally required to have high-speed maneuverability, a polymer having a relatively high molecular weight and a Tg of -60 to -40 ° C, which is not extremely high, is used in order to avoid blowout. It is common to use 70 to 130 parts by weight of carbon black having a small particle size per 100 parts by weight, but it cannot be said that high-speed durability is always sufficient, and since a polymer having a high molecular weight is used, The problem that it is difficult to process in the steps of kneading, extrusion and molding because the viscosity becomes high remains unsolved.

As described above, it has been difficult to provide a composition having both good grip performance and high-speed durability represented by heat resistance and good processability by conventional conventional techniques. Therefore, in order to solve the above problems, a method of using an improved raw material rubber, a method of using an improved carbon black, a tire tread application of good high-speed durability by a method of using a specific vulcanization system Several rubber compositions have been proposed.

For example, Japanese Examined Patent Publication No. 3-77223 discloses a rubber composition for a tire tread that has both low heat buildup and wet grip characteristics and has improved low temperature performance, and has a Tg of -30 ° C to -50 ° C. It has been proposed to use a mixture of the styrene-butadiene copolymer rubber and the polybutadiene rubber having Tg of −70 ° C. or lower as a raw material rubber, and to use a rubber composition having a specific storage shear elastic modulus at −30 ° C. . The proposed technique brings about a decrease in grip performance by blending a polybutadiene rubber, and since it blends a polybutadiene rubber which is originally inferior in processability, no workability has been solved.

Further, Japanese Patent Publication No. 4-53895 discloses that
100 parts by weight of a raw rubber mainly composed of a styrene-butadiene copolymer having a specific structure, and carbon black 80-1
By adding 50 parts by weight and 30 to 120 parts by weight of a softening agent, and using a vulcanization accelerator containing 0.1 to 1.5 parts by weight of a thiuram-based vulcanizing agent, the crosslinked structure after vulcanization is specified. By doing so, a method of providing high speed durability and great grip performance is disclosed. However, this method can improve the performance, but cannot improve the workability.

On the other hand, by hydrogenating the double bond of the butadiene portion of the raw material polybutadiene rubber or the styrene-butadiene copolymer rubber, it has also been possible to improve the performance of the rubber compound used for the tire. Have been proposed to. For example, JP-A-60-252
No. 643 discloses a method of using a rubber composition obtained by hydrogenating a diene copolymer having a polymodal molecular weight distribution curve. JP-A No. 62-283105 discloses a diene copolymer having a terminal functional group. A rubber composition obtained by hydrogenating a polymer is used. Further, in JP-A-63-41547,
A method of using a rubber composition obtained by hydrogenating a branched diene polymer and a linear functional group-containing diene polymer is disclosed.

These methods aim to improve rolling resistance, workability, wear resistance and the like, and heat resistance and weather resistance. However, rolling resistance, workability, and
The improvement in abrasion resistance is due to the shape of the molecular weight distribution curve and the contribution of the terminal functional groups, while hydrogenation of the diene part contributes to the improvement of weather resistance and heat resistance, which is due to the double bond of the diene rubber. It is based on the general idea that the heat resistance and weather resistance, which are the drawbacks of the composition, are improved as the content is reduced. In any case, these methods make grip performance by making the hydrogenated butadiene part and the non-hydrogenated butadiene part exist in a specific ratio.
It was not intended to improve heat resistance and workability, and they did not bring about a composition for tires which is good at high speed running.

Further, JP-A-4-227648 proposes a rubber composition having a high modulus, a high impact resilience and a low exothermicity by selectively partially hydrogenating a vinyl bond of a diene polymer. ing. However, this method alone did not achieve a composition having sufficient grip performance and processability.

[0013]

DISCLOSURE OF THE INVENTION The present invention provides a raw material rubber that provides a rubber compound for passenger car tire treads that has both good grip performance and heat resistance at high speed and has excellent processing performance. Another object of the present invention is to provide a rubber composition.

[0014]

[Means for Solving the Problems] In order to achieve the above objects, the inventors of the present invention have earnestly studied, and as a raw material rubber for a rubber compound for tire tread, use a rubbery polymer having a specific limited polymer structure, Furthermore, they have found that the above problems can be solved by using this rubber-like polymer as a rubber composition having a specific composition, and have reached the present invention.

That is, in the present invention, (A) 100 parts by weight of a selected partially hydrogenated rubber which satisfies the following conditions (a) to (e) is used as a raw material rubber, and (a) the weight ratio of bound styrene / bound butadiene is 25:
/ 75 to 50/50 (b) 1,2 bond amount of the microstructure of the butadiene portion /
A styrene-butadiene copolymer rubber having a 1,4 bond molar ratio of 20/80 to 60/40 is used (c-1) based on the butadiene portion. (C-1) Hydrogenation rate is 10 to 60% (c- 2) Select a butadiene part double bond using a titanium-based hydrogenation catalyst so that the ratio of hydrogenated 1,2 bond amount / hydrogenated double bond amount is 0.6 to 1.0. Partially hydrogenated, (d) Mooney viscosity (ML1 + 4,100 ° C.) of 70-
At 200, (e) glass transition temperature is -50 to -15 ° C. (B) Nitrogen adsorption specific surface area is 90 to ²⁰⁰ m ² / g, D
70 to 200 parts by weight of carbon black having a BP oil absorption of 110 to 200 ml / 100 g, (C) 40 to 100 parts by weight of extender oil, and (D) 1 to 10 parts by weight of vulcanizing agent are blended. A rubber composition for a tire tread and a selected partially hydrogenated rubber of (A) as a raw material in the composition, 50 to 9
Rubber composition for tire tread using 5% by weight and 5% to 50% by weight of one or more rubbers selected from styrene-butadiene copolymer rubber, polybutadiene rubber, natural rubber and polyisoprene rubber Is provided.

The selected partially hydrogenated rubber of the raw rubber constituting the present invention is obtained by selectively and partially hydrogenating the butadiene part of the styrene-butadiene copolymer having a specific structure (hereinafter abbreviated as hydrogenation). It is a rubber-like polymer. The selected partially hydrogenated rubber will be described in detail below.

The weight ratio of bound styrene / bound butadiene of the styrene-butadiene copolymer which is the precursor of the selectively hydrogenated rubber constituting the present invention is in the range of 25/75 to 50/50. If the amount of bound styrene is less than 25% by weight, the grip force of the composition when used in a tire tread is insufficient,
When the amount of bound styrene exceeds 50% by weight, the hardness is increased, and the wear resistance and low temperature performance of the tire tread composition are significantly reduced.

The weight ratio of bound styrene / bound butadiene is preferably in the range 30/70 to 45/55, particularly preferably in the range 30/70 to 42/58. If the weight ratio of bound styrene / bound butadiene is within the above range, it is possible to use styrene that is bound in the molecular chain of the copolymer in any chain form such as random, block or partial block. However, those that do not contain a lot of block styrene that is a series of styrene,
It is preferable from the viewpoint of heat resistance of the composition, and it is preferable that the block ratio of styrene measured by the decomposition method using osmic acid or the ozone decomposition method is 10% by weight or less of the amount of bound styrene.

The selected partial hydrogenated rubber precursor styrene-butadiene copolymer microstructure of the butadiene part of the styrene-butadiene copolymer 1,
The molar ratio of 2 bonds / 1,4 bonds is 20/80 to 60
The range is / 40. The bonding mode of the butadiene moiety includes
There are 1,2 bond (synonymous with vinyl bond), cis-1,4 bond (synonymous with cis bond), and trans-1,4 bond (synonymous with trans bond), and the amount of 1,4 bond in the present invention is , Cis-1,4 bond and trans-1,4 bond.

When the amount of 1,2 bonds is less than 20% and the amount of 1,4 bonds exceeds 80%, the amount of 1,2 bonds that can be hydrogenated is insufficient and heat resistance when used in a tread composition. On the other hand, the amount of 1,2 bonds exceeds 60%, and the amount of 1,4 bonds is 40
If it is less than%, the strength, wear resistance and low temperature performance of the composition are extremely deteriorated. The molar ratio of 1,2 bond amount / 1,4 bond amount is preferably in the range of 25/75 to 55/45,
The molar ratio of binding amount / 1,4 binding amount is 30/70 to 55 /
The range of 45 is more preferable. Each bonding mode of the butadiene moiety may be one that exists uniformly in the molecular chain, or one that has various chain forms such as one that increases or decreases along the molecular chain.

The styrene-butadiene copolymer, which is a precursor of the selected partially hydrogenated rubber, can be prepared by a known method using an organolithium compound in a hydrocarbon solvent such as pentane, hexane, cyclohexane, benzene or toluene. Alternatively, it can be obtained by copolymerizing styrene and butadiene by using as a polymerization initiator with another organic alkali metal compound. The weight ratio of bound styrene / bound butadiene can be adjusted by the charging ratio of the monomers styrene and butadiene used. 1,2 bond amount of butadiene part /
It is possible to add polar compounds such as ethers, polyethers, tertiary amines, and polyamines so that the molar ratio of the 1,4 bond amount falls within the range specified in the present invention.

In general, when an organolithium compound is used as a polymerization initiator, trans-
The 1,4 bond / cis-1,4 bond molar ratio is approximately constant and ranges from 1.3 to 1.5. Further, during or after the polymerization, a functional compound such as divinylbenzene, silicon tetrachloride, tin tetrachloride, polyester, polyepoxide, benzophenone compound, cyclic amide, cyclic imide is added to the system to react with the active lithium terminal. Therefore, a branched polymer or a polymer having a terminal functional group can be obtained, and the branched polymer and the polymer having a terminal functional group can also be used in the present invention by utilizing the characteristics thereof. As a polymer production process, a known method such as a batch method, a continuous method or a combination thereof can be adopted.

The selected partially hydrogenated rubber which constitutes the present invention is prepared by adding water so that the double bond of the butadiene portion of the above-mentioned styrene-butadiene copolymer is made into a specific hydrogenated structure by using a titanium-based hydrogenation catalyst. It is a rubber-like polymer with the added characteristics. This selected partially hydrogenated rubber has a hydrogenation rate in the range of 10 to 60% based on the butadiene portion, and the ratio of hydrogenated 1,2 bond amount / hydrogenated total double bond amount is 0. It must be in the range from 0.6 to 1.0 and the above two requirements for hydrogenation must be met.

When the hydrogenation rate is less than 10%, the effect of improving the heat resistance of the tread composition is small, while the hydrogenation rate is 6%.
If it exceeds 0%, the reactivity with carbon black is reduced, and the strength, abrasion resistance and durability of the tread composition are significantly reduced. The hydrogenation rate is preferably in the range of 10 to 55%, particularly preferably in the range of 15 to 50%.

When the ratio of hydrogenated 1,2 bond amount / hydrogenated total double bond amount is less than 0.6, hydrogenated 1,4 bond amount, that is, tetramethylene unit increases and hardness increases. As a result, workability deteriorates, and heat resistance and wear resistance decrease. The ratio of hydrogenated 1,2 bond amount / hydrogenated double bond amount is 0.7 to 1.0
Is preferred.

In order to obtain the selected partially hydrogenated rubber having the above specific hydrogenated structure, a titanium-based hydrogenation catalyst, that is, an organometallic compound of titanium alone or with lithium,
A method of using a homogeneous hydrogenation catalyst composed of an organometallic compound such as magnesium or aluminum (Japanese Patent Publication No. 63-4841 and Japanese Patent Publication No. 1-37970) under relatively mild conditions of low pressure and low temperature is known. Used.
This catalyst system is capable of hydrogenation reaction in a small amount, and it is not necessary to remove the catalyst residue after the reaction. However, when the hydrogenation rate is higher than the range of the present invention even when this titanium-based hydrogenation catalyst is used, the hydrogenated polymer does not have the desired performance, so the reaction temperature, the amount of catalyst, the amount of hydrogen supplied It is necessary to adjust the hydrogenation rate under such reaction conditions.

Further, by using this titanium-based hydrogenation catalyst system, the hydrogenation selectivity of 1,2 bonds is high, and in addition, even if the molecular weight is the same as that of the polymer before hydrogenation, it is blended. A selected partially hydrogenated rubber having a reduced Mooney viscosity (ML1 + 4,100 ° C.) and improved processability can be obtained.

The Mooney viscosity (ML1 + 4,100 ° C.) of the selected partially hydrogenated rubber of the present invention is in the range of 70 to 200 in order to retain the heat resistance and strength of the tread compound and bring about sufficient processability. Need to be When the Mooney viscosity is less than 70, heat resistance, strength and abrasion resistance are insufficient, and when the Mooney viscosity exceeds 200, workability becomes a problem. The Mooney viscosity is preferably in the range of 80 to 160.

The glass transition temperature (Tg) of the selected partially hydrogenated rubber of the present invention must be in the range of -50 to -15 ° C. The glass transition temperature specified in the present invention is an extrapolation temperature measured using DSC. The glass transition temperature of the selected partially hydrogenated rubber depends on the amount of bound styrene and the bonding mode of the butadiene portion (cis bond, trans bond, 1,2-bond, hydrogenated 1,4 bond, hydrogenated 1,2-bond). It depends on 1,
Due to the selective partial hydrogenation of the 2-bond, the glass transition temperature of the selectively partially hydrogenated rubber is lowered by 1 to 10 ° C. as compared with the polymer before hydrogenation. When the glass transition temperature is less than -50 ° C, the grip performance of the tread compound is low, while the glass transition temperature is-
If it exceeds 15 ° C, low-temperature performance and wear resistance are significantly deteriorated. The glass transition temperature is preferably in the range of −45 to −20 ° C.

The molecular weight distribution (weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)) of the selected partially hydrogenated rubber of the present invention is preferably in the range of 1.05 to 4.0.

The selected partially hydrogenated rubber of the present invention is practically used as an oil-extended rubber by adding 5 to 100 parts by weight of the extender oil for rubber to 100 parts by weight of the selected partially hydrogenated rubber as is done in general rubber. It is possible to use it. When the Mooney viscosity of the selected partially hydrogenated rubber is 80 or more, it is preferable to use an oil-extended rubber in order to improve processability. Oil-extended Mooney viscosity when using oil-extended rubber (ML1 + 4,100 ℃)
Is preferably in the range of 30 to 80. As the extender oil to be used, aromatic type, naphthene type and paraffin type ones are used, and among them, the aromatic type extender oil is preferable. When the oil-extended polymer is used, the Tg of the selected partially hydrogenated rubber of the present invention changes depending on the amount of the extender oil, as is known in general oil-extended polymers. It is necessary to keep in mind that it is a weight average value of the Tg of the oil and the Tg of the extending oil.

Next, in the rubber composition of the present invention, by using the reinforcing carbon black having a specific property in a specific amount range, grip performance is imparted and good abrasion resistance is obtained. . In the present invention, the selected partially hydrogenated rubber is used alone as a raw material rubber for a rubber composition, or is used together with another rubber-like polymer in a range not losing the characteristics of the selected partially hydrogenated rubber. When used with other rubber-like polymers, the selected partially hydrogenated rubber is 50 to 50% of the raw rubber.
Used in the range of 95% by weight.

The rubber used in the present invention together with the selected partially hydrogenated rubber in the range of 5 to 50% by weight of the raw rubber is selected from polybutadiene rubber or styrene-butadiene copolymer rubber, natural rubber and polyisoprene rubber. It is one kind or two or more kinds. These rubbers are used for the tire tread rubber of the present invention together with the selected partially hydrogenated rubber for the purpose of improving the workability, strength, low temperature performance and the like of the rubber composition for the tire tread of the present invention, and they are selected. It should not significantly impair the advantages of the rubber composition for a tire tread brought about by the partially hydrogenated rubber in grip performance and heat resistance.

The carbon black used in the rubber composition of the present invention has a nitrogen adsorption specific surface area of 90 to ²⁰⁰ m ² / g,
DBP oil absorption is 110 to 200 ml / 100 g of carbon black, and is 70 per 100 parts by weight of raw rubber.
~ 200 parts by weight are used. This carbon black has a small particle size and is highly active as compared with standard carbon black. Carbon black has a nitrogen adsorption specific surface area of 9
If it is less than 0 or the DBP oil absorption is less than 110, the strength and wear resistance are poor. On the other hand, if the carbon black has a nitrogen adsorption specific surface area of more than 200 or a DBP oil absorption of 200,
If it exceeds the range, poor dispersion and poor processability are exhibited.

When the amount of carbon black is less than 70 parts by weight with respect to 100 parts by weight of the raw rubber, grip is insufficient, and when it exceeds 200 parts by weight, workability is deteriorated and heat resistance is deteriorated. The amount of carbon black is 80 to 150
A range of parts by weight is preferred. Furthermore, it is also possible to use an inorganic reinforcing agent or filler such as silica, clay or calcium carbonate together with carbon black, if necessary.

Next, an extender oil for rubber is used in the rubbery polymer composition of the present invention, and 40 to 100 parts by weight is blended per 100 parts by weight of the rubbery polymer. The amount of extender oil for rubber is increased according to the amount of carbon black and is used to adjust the elastic modulus of the vulcanized tread compound. If the amount of the extender oil for rubber is less than 40 parts by weight, the elastic modulus of the tread compound will be too high, resulting in insufficient steering stability.
If it exceeds the weight part, heat resistance is deteriorated.

Next, in the rubbery polymer composition of the present invention, the vulcanizing agent is added in an amount of 1 to 10 per 100 parts by weight of the rubbery polymer.
Used in parts by weight. Sulfur is used as a typical vulcanizing agent, and in addition, sulfur-containing compounds, peroxides, etc. are used. In addition, a vulcanization accelerator such as a sulfenamide-based, guanidine-based, or thiuram-based vulcanization accelerator is used in combination with a vulcanizing agent, if necessary. Furthermore, zinc rubber, stearic acid, a vulcanization aid, an antiaging agent, and a processing aid are used as rubber chemicals in necessary amounts for the purpose.

The rubber-like polymer composition of the present invention is prepared by kneading a raw material rubber and carbon black, extending oil for rubber, chemicals for rubber and the like using an internal mixer or a mixing roll, and further adding sulfur such as sulfur. After being mixed with a vulcanizing agent and a vulcanization accelerator and molded, the vulcanized rubber compound, which is vulcanized at a temperature of 140 to 180 ° C., exhibits its performance and is used for a tire tread.

The rubber-like polymer of the present invention is preferably used in the form of a vulcanized rubber compound containing carbon black in a tire tread compound represented by high performance tires and all-season tires. It can also be applied to other tire applications, anti-vibration rubber, belts, industrial products, footwear, etc.

[0040]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but these do not limit the scope of the present invention.

Reference Example Production Method of Selected Partly Hydrogenated Rubber: Two autoclaves each having an inner volume of 10 liters, an inlet at the bottom and an outlet at the head, a stirrer and a jacket are connected as a reactor in series, and 1 Using a metering pump from the bottom of the base reactor, 20.7 g / min of butadiene, 9.3 g / min of styrene, 120 g / min of cyclohexane, 0.022 g / min of tetramethylethylenediamine as a polar substance, and a polymerization initiator. , N-butyllithium was continuously supplied at a rate of 0.011 g / min, and the reactor internal temperature was maintained at 100 ° C. Withdraw the polymer solution continuously from the reactor head,
The second reactor was fed. The second reactor was charged with 0.5 equivalent of tetraglycidyl-1,3 per mol of the active polymer.
-Bisaminocyclohexane was continuously added to cause a coupling reaction.

The obtained polymer solution was continuously fed to another autoclave type reactor equipped with a stirrer and a jacket with another internal volume of 10 liters, and used as a hydrogenation catalyst, g-p-
A mixture of trilyl-bis (1-cyclopentadienyl) titanium / cyclohexane solution and n-butyllithium / n-hexane solution was mixed with titanium at 50
An amount of ppm was continuously added, and this polymer solution was introduced into an atomizer and continuously hydrogenated at 2.5 kg / cm ² of hydrogen.

After the addition of the antioxidant, the solvent was removed to obtain a partially hydrogenated rubber selected for analysis. Furthermore, an aromatic oil (X-14 manufactured by Japan Energy Co., Ltd.) was added to the polymer solution.
0) was added to 37.5 parts by weight per 100 parts by weight of the polymer to obtain an oil-extended rubber (Sample A-3). Further, selected partial rubbers (Samples A-2, A-4 to A-7) having different hydrogenation rates were obtained by changing the hydrogen pressure in the atomizer, the hydrogenation catalyst amount, and the stirring conditions. Also, collect a part of the polymer solution before hydrogenation,
After adding the antioxidant, the solvent was removed to obtain an unhydrogenated polymer (Sample A-1).

The sample A-1 was analyzed to find that the amount of bound styrene was 31%, the amount of bound butadiene was 69%, and the butadiene portion was calculated from the measurement results using an infrared spectrophotometer according to the Hampton method. The microstructure of is 1,2-bond 32%, cis-1,4 29%, trans-
39% of 1,4 bond, Mooney viscosity (ML1 + 4,1
00 ° C) is 140, glass transition temperature is -42 ° C, THF
Measurement using GPC as a solvent (pump: Shimadzu LC-5
A, column: HSG-40, 50, 60 each 1 piece, detector: RI molecular weight distribution, weight average molecular weight (M
w) is 485,000, the number average molecular weight (Mn) is 18.3,
The molecular weight distribution (Mw / Mn) was 2.65, and the shape of the GPC curve was monomodal.

Further, in the same manner as in obtaining the sample A-1, the amount of bound styrene, the amount of 1,2 bonds in the butadiene portion,
Polymers (Samples (B-1, C-1, F-1) before hydrogenation having different Mooney viscosities and glass transition temperatures were prepared.
These were subjected to the same hydrogenation reaction as that for obtaining Sample A-3,
Selected partially hydrogenated polymers having different amounts of bound styrene, 1,2 bonds of butadiene part, hydrogenation rate, Mooney viscosity, and glass transition temperature (Samples B-2 to B-5, C-2 to C-
3, D-1, E-1, F-2, G-1, H-1, J-
1, K-1, L-1, M-1, Q-1) were obtained.

For samples N-1 and P-1, the polymer before hydrogenation was prepared in the same manner as in sample A-1, and nickel naphthenate / n-butyllithium / hydrogen catalyst was used as a hydrogenation catalyst. This is a partially hydrogenated polymer obtained by carrying out a hydrogenation reaction using a solution prepared by previously mixing and mixing tetrahydrofuran = 1/8/20 (molar ratio), and is a sample for comparison.

The analysis values of the above samples are shown in Table 1-1 to Table 1-4.
Shown in The analysis was performed by the method shown below. 1) Amount of bound styrene and amount of bound butadiene The polymer before hydrogenation was used as a chloroform solution, and the amount of bound styrene [S] (wt%) was measured by absorption of UV at 254 nm by the phenyl group of styrene, and the amount of bound butadiene (w
t%) was calculated as 100- [S].

2) 1,2 bond amount of butadiene part, 1,
4 Bond amount The polymer before hydrogenation was made into a heavy chloroform solution, and FT-NM was used.
R (270 MHz, manufactured by JEOL Ltd.), ¹ H-N
Measure MR spectrum, chemical shift 4.7-5.2p
pm proton by 1,2 bonds (and signal C0 to) (= CH _2), chemical shifts 5.2~5.8ppm
The amount of 1,2 bonds [V] from the integrated intensity ratio of protons (= CH-) due to 1,4 bonds of (signal D0)
(% In BD) was calculated by the following formula. [V] = {2C0 / (C0 + 2D0)} × 100 1,4 bond amount (% in BD) = 100− [V]

3) Hydrogenation rate The integrated strength of 1,2 bond and 1,4 bond of the polymer before hydrogenation was determined by the method of ¹ H-NMR spectrum shown in 2). The ¹ H-NMR spectrum of the partially hydrogenated polymer was measured in the same manner, and a methyl proton (—CH ₃ ) with a hydrogenated 1,2 bond having a chemical shift of 0.6 to 1.0 ppm (signal A1), Chemical shift 4.7-5.2 pp
Proton (= CH ₂ ) due to unhydrogenated 1,2 bond of m (denoted as signal C1), chemical shift 5.2
The integrated intensity of 5.8 ppm (denoted as signal D1) of unhydrogenated 1,4 bond protons (= CH-) was obtained, and the hydrogenation rate was calculated as follows.

First, p = 3C0 / (3C1 + 2A1) A11 = p.times.A1 C11 = p.times.C1 D11 = p.times.D1 The hydrogenation rate [B] (%) of 1,2 bond was calculated by the following equation. [B] = {2A11 / (2A11 + 3C11)} × 100 The hydrogenation rate [C] (%) of 1,4 bond was calculated by the following formula. [C] = {(2D0-C0-2D11 + C11) (2D0-C
0)} × 100 The hydrogenation rate [A] (% in BD) of the entire butadiene part was obtained by the following formula. [A] = {[V] × [B] + (100− [V]) ×
[C]} / 100 Hydrogenated 1,2 bond amount [Hv] and hydrogenated 1,4 bond amount [Hb] [Hv] (% in BD) = [V] × [B] / 100 [ Hb] (% in BD) = (100− [V]) × [C] / 1
00

4) Glass transition temperature Measured at a temperature rising rate of 10 ° C./min using DSC. The extrapolation start temperature (On setpoint) was taken as Tg.

Examples 1 to 13 and Comparative Examples 1 to 15 Using the samples shown in Tables 1-1 to 1-4 as raw rubbers, rubber compounds were obtained by the following compounding and kneading methods.

[Compounding] Raw material rubber (selected partially hydrogenated polymer or unhydrogenated polymer) 100 carbon black N234 ^{* 1} 85 aromatic oil X-140 50 ^{* 2} lead zinc 3 stearic acid 2 antioxidant 810NA ^{* 3} 1 Vulcanization accelerator CZ ^{* 4} 1.6 Sulfur yellow 2.4 ^{* 1} Tokai Carbon Co., Ltd. Seast 7H Nitrogen adsorption specific surface area 131 m ² / g DBP oil absorption 123 ml / 100 g ^{* 2 The} amount is included in the oil-extended polymer. Total amount and additional amount ^{* 3} N-isopropyl-N'-phenyl-p-phenylenediamine Ouchi Shinko Co., Ltd. Nocrac 810NA ^{* 4} N-Cyclhexyl-2-benzothiazylsulfenamide Ouchi Shinko NOXCELLER CZ Co., Ltd.

[Kneading method] B type Banbury mixer (capacity 1.7 liters) was used. Raw rubber, carbon black, aromatic oil, zinc oxide, stearic acid, and antioxidant are kneaded, and the maximum temperature reached is 170 ° C.) After cooling, sulfur and vulcanization accelerator are kneaded with an open roll set at 80 ° C. This was molded and vulcanized at 160 ° C. for 20 minutes with a vulcanizing press, and the performance of physical properties showing the following tire performance was measured.

1) Formulation Mooney Viscosity: Measured at 100 ° C. using a Mooney viscometer. The smaller the value, the better the workability. 2) Hardness: Measured by JIS-K-6301 JIS-A hardness meter. 3) Tensile strength: Measured by the tensile test method of JIS-K-6301. 4) Heat resistance: Goodrich flexometer is used. Rotation speed 1800 rpm, stroke 0.225 inch, load 55 pounds, starting temperature 100 ° C, difference ΔT between temperature after 20 minutes and starting temperature is measured.

5) Grip performance: Calculated from the values of E'and Tan δ measured using a viscoelasticity spectrometer (manufactured by Iwamoto Seisakusho) under the conditions of 10 Hz, 0 ° C. and dynamic strain of ± 1%. The larger the value, the better the grip performance. 6) Abrasion resistance: Measured using a pico abrasion tester. The larger the value, the better the wear resistance.

The results of performance measurement are shown in Tables 2-1 and 2-2. Further, FIG. 1 shows a balance between grip performance and heat resistance. The compositions using the selectively hydrogenated rubbers of Examples 1 to 15 limited by the present invention show good heat resistance, grip performance, and wear resistance. On the other hand, the compositions of Comparative Examples 1, 4, 6, 7 using a non-hydrogenated polymer and Comparative Example 2 using a polymer partially hydrogenated but less than the limitation of the present invention. All the compositions have poor heat resistance.

Comparative Example 3 is a composition using a polymer in which the ratio of hydrogenated 1,2 bonds is less than the limit of the present invention,
Comparative Example 5 is a composition having a hydrogenation rate higher than the limit of the present invention, but all of them are not preferable because of poor workability, high hardness and low tensile strength. In Comparative Example 8, the glass transition temperature of the raw rubber is lower than the limit of the present invention, and the grip performance of the composition is poor.

In Comparative Example 9, the amount of bound styrene of the raw material rubber is less than the limit of the present invention, the grip performance corresponding to the glass transition temperature cannot be obtained, and the tensile strength and abrasion resistance are poor. In Comparative Example 10, the amount of 1,4 bond of the raw rubber is less than the limit of the present invention, the hardness is too high and the heat resistance is poor. In Comparative Example 11, the amount of bound styrene of the raw material rubber is more than the limit of the present invention, the hardness is significantly increased, and the heat resistance is poor.

In Comparative Example 12, the amount of 1,2 bonds of the raw rubber is larger than the limit of the present invention, and the tensile strength and the high abrasion resistance are inferior. In Comparative Examples 13 and 14, the hydrogenation catalyst is not limited to the present invention, the ratio of hydrogenated 1,2 bonds is lower than the limitation of the present application, and both have poor heat resistance. In Comparative Example 15, the Mooney viscosity of the raw material rubber is lower than the limit of the present invention, and the heat resistance is poor.

Examples 2, 14 to 16 and Comparative Examples 16 to 18 The selected partially hydrogenated rubbers of Sample A-4 were used as raw material rubbers.
A rubber composition having the composition shown in Table 3 was prepared in the same manner as in Example 1, and the performance was measured. Table 3 shows the results. The compositions of Examples 2 and 14 to 16 in which the carbon black having the properties limited by the present invention was used in the amount limited by the present invention, exhibited good heat resistance, grip performance, and abrasion resistance.

In Comparative Example 16, the amount of carbon black blended is less than the limit of the present invention, and the grip is poor. Comparative Example 17
The amount of aromatic oil is less than the limit of the present invention, the workability is poor, and the hardness is too high, so the grip performance is poor. Comparative Example 18 is a carbon black that does not fall within the range of characteristics limited by the present invention, and has poor grip performance and abrasion resistance.

Examples 17 to 21 and Comparative Examples 19 to 20 The selected partially hydrogenated rubbers of Sample B-3 or Sample F-2 were used, and a blend system with other rubbers shown in Table 4 was used as a raw material rubber and shown in Table 4. A rubber composition having the formulation shown in Example 1 was prepared,
The performance was measured. The results are shown in Table 4. As shown in Table 4, the compositions of Examples 17 to 21 of the present invention show good heat resistance, grip performance, and wear resistance. On the other hand, the compositions of Comparative Examples 19 and 20 are inferior in grip performance.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

[0068]

[Table 5]

[0069]

[Table 6]

[0070]

[Table 7]

[0071]

[Table 8]

[0072]

EFFECT OF THE INVENTION By using the selected partially hydrogenated rubber of the present invention, which has the specified partial hydrogenation selectivity, in a composition containing a specific carbon black, a rubber for a tire tread excellent in processability, grip and high-speed durability. A composition is provided. This rubber composition for tires is useful as a material for automobile tires that require a high speed performance.

[Brief description of drawings]

FIG. 1 is a diagram showing a good balance between grip performance and heat resistance of the composition of the present invention.

Claims (2)

[Claims] 1. (A) 100 parts by weight of a selected partially hydrogenated rubber as a raw material rubber satisfying the following conditions (a) to (e), and (a) a weight ratio of bound styrene / bound butadiene is 25:
/ 75 to 50/50 (b) 1,2 bond amount of the microstructure of the butadiene portion /
A styrene-butadiene copolymer rubber having a 1,4 bond molar ratio of 20/80 to 60/40 is used (c-1) based on the butadiene portion. (C-1) Hydrogenation rate is 10 to 60% (c- 2) Select a butadiene part double bond using a titanium-based hydrogenation catalyst so that the ratio of hydrogenated 1,2 bond amount / hydrogenated double bond amount is 0.6 to 1.0. Partially hydrogenated, (d) Mooney viscosity (ML1 + 4,100 ° C.) of 70-
200, (e) glass transition temperature is -50 to -15 ° C. (B) Nitrogen adsorption specific surface area is 90 to ²⁰⁰ m ² / g, D
70 to 200 parts by weight of carbon black having a BP oil absorption of 110 to 200 ml / 100 g, (C) 40 to 100 parts by weight of extender oil, and (D) 1 to 10 parts by weight of a vulcanizing agent were blended. Rubber composition for tire tread. 2. (A-1) The selected partially hydrogenated rubber satisfying the following conditions (a) to (e) is 50 to 95% by weight of the raw rubber.
And (a) the weight ratio of bound styrene / bound butadiene is 25
/ 75 to 50/50 (b) 1,2 bond amount of the microstructure of the butadiene portion /
A styrene-butadiene copolymer rubber in which the molar ratio of the amount of 1,4 bonds is 20/80 to 60/40 is (c) based on the butadiene portion. (C-1) Hydrogenation rate is 10 to 60% (c- 2) Select a butadiene part double bond using a titanium-based hydrogenation catalyst so that the ratio of hydrogenated 1,2 bond amount / hydrogenated double bond amount is 0.6 to 1.0. Partially hydrogenated, (d) Mooney viscosity (ML1 + 4,100 ° C.) of 70-
200, (e) glass transition temperature is -50 to -15 ° C. (A-2) One or more rubber selected from styrene-butadiene copolymer rubber, polybutadiene rubber, natural rubber and polyisoprene rubber is 5 to 50% by weight of the raw rubber.
(B) nitrogen adsorption specific surface area is 90 to ²⁰⁰ m ² / g, D
70 to 200 parts by weight of carbon black having a BP oil absorption of 110 to 200 ml / 100 g, (C) 40 to 100 parts by weight of extender oil for rubber, and (D) 1 to 10 parts by weight of vulcanizing agent were blended. Rubber composition for tire tread.