Rubber composition and tire by using the same

The present invention relates to a rubber composition and a tire using the same.

Conventionally, in order to obtain a rubber composition showing high grip performance, for example, a rubber composition using styrene-butadiene copolymer rubber (SBR) having a high glass transition temperature (Tg) as a rubber component and process oil are highly softened. A rubber composition in which an equal amount was substituted with a point resin and filled with a rubber component, a rubber composition highly filled with a softening agent or carbon black, or a combination of the SBR, a highly softening point resin, the softening agent or carbon black was blended. Rubber compositions are known. However, the rubber composition using SBR having a high Tg has a problem that the temperature dependence becomes large and the performance change with respect to the temperature change becomes large. Further, when carbon black having a small particle size or a large amount of softener is used, there is a problem that the dispersibility of carbon black is poor and the wear resistance is lowered.

In order to improve these problems, a rubber composition using a low molecular weight styrene-butadiene copolymer has been proposed (see Patent Document 1). However, since the low molecular weight styrene-butadiene copolymer has a crosslinkable double bond, some low molecular weight components form crosslinks with the rubber component of the matrix and are incorporated into the matrix, resulting in sufficient hysteresis loss. There is a problem that it cannot be suppressed. Further, in order to prevent low molecular weight components from being incorporated into the matrix by cross-linking, when the double bond portion is saturated by hydrogenation, the compatibility with the matrix is significantly lowered, and as a result, the fracture resistance is lowered. There is a problem that low molecular weight components are bleeding.

Further, in order to improve high grip performance (wet grip performance) on a wet road surface, a rubber composition containing a halogenated butyl rubber or a halide of a copolymer of isobutylene and p-methylstyrene and silica has been proposed. (See Patent Document 2). However, this is an inadequate balance between grip performance and wear resistance. Similarly, in order to improve the wet grip performance, it has been proposed to use hydrogenated SBR for silica compounding (see Patent Document 3). However, the improvement of wet grip performance cannot be sufficiently improved.

<patcit num="1"><text>JP-A-63-101440</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2000-204198</text></patcit><patcit num="3"><text>International Publication No. 96/005250 Pamphlet</text></patcit>

<p> An object of the present invention is to provide a rubber composition having a well-balanced improvement in wet grip performance and wear resistance, and a tire using the same.</p>

<p> The present invention is a rubber component containing (A) a halide of butyl rubber halide or a copolymer of isobutylene and p-methylstyrene, and (B) a copolymer of a conjugated diene compound and an aromatic vinyl compound by solution polymerization. For 100 parts by weight, (C) low molecular weight aromatic vinyl-conjugated diene copolymer is 5 to 100 parts by weight, and (D) nitrogen adsorption specific surface area is 100 to 300 m.²A rubber composition containing 40 to 150 parts by weight of silica of / g, (E) 10 to 180 parts by weight of a softener, and (F) a silane coupling agent, which is a conjugated diene compound and an aromatic vinyl compound. Weight average molecular weight of copolymer (B) by solution polymerization is 5.0 × 10⁵~2.5×10⁶, The aromatic vinyl content is 20-60% by weight, the glass transition temperature is -70 to 0 ° C, and the vinyl bond amount in the conjugated diene is 15 to 70% by weight, and the low molecular weight aromatic vinyl-conjugated. The diene copolymer (C) is obtained by hydrogenating a low molecular weight aromatic vinyl-conjugated diene copolymer having a vinyl bond amount of 20 to 70% by weight in the conjugated diene portion, and is a copolymer (C). Weight average molecular weight of 1.0 × 10³~1.0×10⁵The rubber composition has an aromatic vinyl content of 10 to 75% by weight and a hydrogenation rate of 20 to 60%.</p><p> The rubber composition preferably contains 5 to 40 parts by weight of the low molecular weight aromatic vinyl-conjugated diene copolymer (C).</p><p> The present invention relates to a tire using the rubber composition.</p>

<p> According to the present invention, a specific rubber component, a hydrogenated low molecular weight aromatic vinyl-conjugated diene copolymer, silica, a softener, and a silane coupling agent are blended into a rubber composition to provide wet grip performance and resistance. Abrasion properties can be improved in a well-balanced manner.</p>

The rubber composition of the present invention includes (A) butyl rubber halide (hereinafter referred to as X-IIR) or a halide of a copolymer of isobutylene and p-methylstyrene (hereinafter referred to as X-IB-PMS). And (B) a rubber component containing a copolymer by solution polymerization of a conjugated diene compound and an aromatic vinyl compound, (C) a low molecular weight aromatic vinyl-conjugated diene copolymer, (D) silica, (E) a softener, It also consists of (F) silane coupling agent.

As the component (A) (hereinafter referred to as a halide (A)), X-IIR or X-IB-PMS is used. These may be used alone or in combination. Of these, it is preferable to use X-IB-PMS because it has excellent co-crosslinkability with other diene rubbers and can further improve wet grip performance and wear resistance.

The X-IIR may be any as long as it is generally used for rubber compounding, and there is no particular limitation, but the halogen content is 1.1 to 1.3% for chlorinated butyl rubber and 1.8 to 2.4% for brominated butyl rubber. preferable. Further, from the viewpoint of processability, it is preferable that the Mooney viscosity (@ 125 ° C) is 20 to 60, more preferably 25 to 55. Preferred specific examples include, for example, Chlorobutyl 1066, Chlorobutyl 1068, Bromobutyl 2244, and Bromobutyl 2255 manufactured by Nippon Synthetic Rubber Co., Ltd. and Exxon Scientific Co., Ltd.

The X-IB-PMS preferably has an isobutylene unit amount / p-methylstyrene unit amount of 90/10 to 98/2 by weight and a halogen content of 5 to 7% from the viewpoint of cocrosslinkability. As a preferable specific example, for example, Exxpro90-10 (trade name) manufactured by Exxon Chemical Co., Ltd. can be mentioned.

The component (B) (hereinafter referred to as copolymer (B)) is composed of a copolymer obtained by solution polymerization of a conjugated diene compound and an aromatic vinyl compound. Here, examples of the conjugated diene component include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene and the like. These may be used alone or in admixture of two or more. Of these, 1,3-butadiene is preferable. The aromatic vinyl component includes vinyl aromatics such as styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, and 2,4-trimethylstyrene. Examples include hydrocarbon monomers. These may be used alone or in admixture of two or more. Of these, styrene is preferable.

The copolymer (B) is obtained by solution-polymerizing the conjugated diene compound and an aromatic vinyl compound. Solution polymerization has the effect of facilitating control of the vinyl bond amount and molecular weight distribution in the conjugated diene portion.

The weight average molecular weight of the copolymer (B) is 5.0 × 10.⁵Above, preferably 7.5 × 10⁵That is all. Weight average molecular weight is 5.0 × 10⁵If it is less than, the wear resistance is lowered. The weight average molecular weight is 2.5 x 10⁶The following, preferably 2.0 × 10⁶It is as follows. Weight average molecular weight is 2.5 × 10⁶If it exceeds, the workability is lowered.

The aromatic vinyl content of the copolymer (B) is 20% by weight or more in the copolymer (B). If the aromatic vinyl content is less than 20% by weight, the wet grip performance is low. The aromatic vinyl content of the copolymer (B) is 60% by weight or less, preferably 50% by weight or less. When the aromatic vinyl content exceeds 60% by weight, when it exceeds 60% by weight, the wear resistance is lowered and the wet grip performance at low temperature is also lowered.

The glass transition temperature of the copolymer (B) is -70 ° C or higher, preferably -50 ° C or higher. If the glass transition temperature is less than -70 ° C, the wet performance is inferior. The glass transition temperature is 0 ° C or less. When the glass transition temperature exceeds 0 ° C, it tends to become excessively hard or brittle at low temperatures.

The vinyl bond amount in the conjugated diene portion of the copolymer (B) is 15% by weight or more, preferably 30% by weight or more. If the vinyl bond amount is less than 15% by weight, the wet grip performance is low. The vinyl bond amount is 70% by weight or less, preferably 50% by weight or less. If the vinyl bond amount exceeds 70% by weight, the wear resistance is lowered and the wet grip performance at low temperature is also lowered.

The rubber component consists of a halide (A) and a copolymer (B).

The content of the halide (A) in the rubber component is preferably 20% by weight or more, more preferably 30% by weight or more, in that it is excellent in the effect of improving wear resistance and wet grip performance. Further, it is preferably 60% by weight or less, and more preferably 50% by weight or less.

The content of the copolymer (B) in the rubber component is preferably 40% by weight or more, preferably 50% by weight or more, in that the effect of improving wear resistance and wet grip performance is also excellent. More preferably, it is 80% by weight or less, and more preferably 70% by weight or less.

Examples of the aromatic vinyl component in the low molecular weight aromatic vinyl-conjugated diene copolymer (C) (hereinafter referred to as copolymer (C)) include styrene, α-methylstyrene, 1-vinylnaphthalene, and 3-vinyl. Examples thereof include vinyl aromatic hydrocarbon monomers such as toluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, and 2,4-trimethylstyrene. These may be used alone or in admixture of two or more. Of these, styrene is preferable.

Examples of the conjugated diene component in the copolymer (C) include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene and the like. These may be used alone or in admixture of two or more. Of these, 1,3-butadiene is preferable.

The copolymer (C) is obtained by hydrogenating a copolymer having a vinyl bond amount of 20% by weight or more, preferably 30% by weight or more in the conjugated diene portion. If the vinyl bond amount is less than 20% by weight, sufficient wet grip performance cannot be obtained. Further, the copolymer (C) is obtained by hydrogenating a copolymer sub-polymer having a vinyl bond amount of 70% by weight or less. If it exceeds 70% by weight, the wear resistance will decrease.

The weight average molecular weight of the copolymer (C) is 1.0 × 10.³Above, preferably 2.0 × 10³That is all. Weight average molecular weight is 1.0 × 10³If it is less than, the wear resistance is not sufficient. The weight average molecular weight is 1.0 × 10.⁵Below, preferably 8.0 × 10⁴It is as follows. Weight average molecular weight is 1.0 × 10⁵If it exceeds, sufficient wet grip performance cannot be obtained.

The aromatic vinyl content in the copolymer (C) is 10% by weight or more, preferably 20% by weight or more. If the vinyl content is less than 10% by weight, sufficient wet grip performance cannot be obtained. The aromatic vinyl content is 75% by weight or less, preferably 50% by weight or less. If the aromatic vinyl content exceeds 75% by weight, the abrasion resistance will decrease.

The hydrogenation rate of the double bond of the conjugated diene portion in the copolymer (C) is 20% or more, preferably 30% or more, more preferably 40% or more, further preferably 43% or more, and particularly preferably 45%. .. If the hydrogenation rate is less than 20%, the copolymer (C) is incorporated into the rubber component which is a matrix, and sufficient wet grip performance cannot be obtained. The hydrogenation rate is 60% or less, preferably 55% or less, and more preferably 50% or less. If the hydrogenation rate exceeds 60%, the rubber composition becomes hard and sufficient wet grip performance and wear resistance cannot be obtained, and there is a possibility of bleeding out.

The content of the copolymer (C) is 5 parts by weight or more, preferably 15 parts by weight or more, and more preferably 20 parts by weight or more with respect to 100 parts by weight of the rubber component. If the blending amount is less than 5 parts by weight, sufficient wet grip performance cannot be obtained. The content is 100 parts by weight or less, preferably 70 parts by weight or less, and more preferably 40 parts by weight or less. If the content exceeds 100 parts by weight, not only the workability is lowered, but also the wear resistance is lowered.

Nitrogen adsorption specific surface area (N) used in the present invention₂SA) is 100 ~ 300m²Silica (D) of / g is formulated to improve wet performance.

The N₂SA gives a reinforcing effect, does not deteriorate the dispersibility, and suppresses heat generation, so it is 100m.²/ g or more, 300m²It may be less than / g, but from the viewpoint of wear resistance (strength), it is 100m.²/ g or more, 250m²It is preferably less than / g. N₂SA is 100m²If it is smaller than / g, the reinforcing effect is small and 300m²If it exceeds / g, the dispersibility is poor and heat generation increases.

Examples of silica (D) include dry silica (silicic anhydride) and wet silica (hydrous silicic acid) that satisfy the above requirements. Preferred specific examples include, for example, Nipcil VN3 and Nipcil AQ manufactured by Nippon Silica Co., Ltd., and Ultrasil VN3 manufactured by Degussa Co., Ltd.

The blending amount of silica (D) is 40 parts by weight or more, preferably 50 parts by weight or more with respect to 100 parts by weight of the rubber component. If the blending amount is less than 40 parts, the improvement in rolling resistance and wet skid performance of the silica-blended rubber composition becomes small. The blending amount is 150 parts by weight or less, preferably 130 parts by weight or more. If the blending amount exceeds 150 parts by weight, it becomes difficult to knead the rubber, and conversely, the wear resistance deteriorates and the rolling resistance increases.

The softening agent (E) may be any as long as it has been conventionally used in the field of rubber compositions, and is not particularly limited. For example, paraffin-based process oils, naphthen-based process oils, aromatic process oils, etc. Examples include special process oil. These may be used alone or in combination of two or more. Of these, aromatic process oils, naphthenic process oils, and special process oils are preferable from the viewpoint of achieving both workability and performance.

The blending amount of the softening agent (E) is 10 parts by weight or more with respect to 100 parts by weight of the rubber component from the viewpoint of processability and performance of the rubber composition containing silica. If the blending amount of the softener (E) is less than 10 parts by weight, a filler such as silica cannot be highly filled. The blending amount of the softener (E) is 180 parts by weight or less, preferably 160 parts by weight or less. If it exceeds 180 parts by weight, workability, wear resistance, and tensile strength will decrease.

As the silane coupling agent (F), any silane coupling agent conventionally used in combination with silica can be used, but the general formula (1): Z-Alk-S_n-Alk-Z (1) (In the formula, Z is -Si (R)¹)₂R²,-SiR¹(R²)₂, -Si (R)²)₃(However, R¹Is an alkyl group with 1 to 4 carbon atoms, a cyclohexyl group or a phenyl group, R²Represents an alkoxy group having 1 to 8 carbon atoms or a cycloalkoxy group having 5 to 8 carbon atoms, and R¹2 or R²If two or more are included, they may be the same or different), Alk represents a divalent hydrocarbon group with 1 to 18 carbon atoms, n represents an integer from 2 to 8, and Z containing 2 each. , Alk may be the same or different, respectively) or general expression (2): Z-Alk-SH (2) In the formula, Z and Alk are preferably the same as described above. Specifically, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) Tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane , 3-Chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-Triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazoletetrasulfide, 3-triethoxysilyl Examples thereof include propylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide. These may be used alone or in combination of two or more. Of these, bis (3-triethoxysilylpropyl) tetrasulfide is preferable from the viewpoint of achieving both the effect of adding a silane coupling agent and the cost.

The blending amount of the silane coupling agent (F) may be a range that does not impair the effects of the present invention, but from the viewpoint of performance improvement and workability, 5 parts by weight with respect to 100 parts by weight of silica (D). The above is preferable. If the blending amount of the coupling agent (F) is less than 5 parts by weight, the silica tends to be poorly dispersed and the wear resistance and rolling resistance tend to be deteriorated. The amount of the coupling agent (F) to be blended is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less. If it exceeds 20 parts by weight, the rubber becomes too hard and the wet grip performance tends to deteriorate.

Further, in the rubber composition of the present invention, in addition to the above-mentioned components, various chemicals usually used in the rubber industry, for example, vulcanizing agents such as sulfur, various vulcanization accelerators, various antioxidants, stearic acid, etc. Additives such as zinc oxide, antioxidants, and ozone deterioration inhibitors can be blended.

The tire of the present invention is produced by a conventional method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention containing the various chemicals is extruded according to the shape of each member of the tire at the unvulcanized stage, and molded by a normal method on a tire molding machine. And form an unvulcanized tire. This unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited thereto.

(Synthesis of copolymer) The weight average molecular weight (Mw) was determined by using a GPC-8000 series device manufactured by Toso Co., Ltd., a differential refractometer was used as a detector, and the molecular weight was composed of standard polystyrene. The microstructure is at 25 ° C using the JEOL JNM-A 400 NMR device.¹1 H NMR was measured and its composition was determined from the ratio of phenyl protons based on styrene units of 6.7 to 7.2 ppm and methylene protons of vinyl bond based on butadiene units of 4.7 to 5.2 ppm obtained from the spectrum. Regarding the hydrogenation rate, 0.6 to 1.0 ppm of hydrogenated vinyl-bonded methyl protons and 4.7 to 5.2 ppm of unhydrogenated vinyl-bonded methylene protons of 5.2 to 5.8 ppm of unhydrogenated cis and trans. , Obtained by calculation from vinyl-bonded methine protons.

(Synthesis of Styrene-butadiene Copolymer (B) -1) 1000 g of cyclohexane, 20 g of tetrahydrofuran (THF), 80 g of 1,3-butadiene and 40 g of styrene were introduced into a 2 L autoclave with a fully nitrogen-substituted stirrer. The temperature in the autoclave was adjusted to 25 ° C. Next, 0.05 g of n-butyllithium was added and polymerized for 60 minutes under high temperature conditions, and it was confirmed that the conversion rate of the monomer was 99%. Then, 1.5 g of 2,6-di-t-butyl-p-cresol was added as an antioxidant. The results are shown in Table 1.

(Synthesis of Styrene-butadiene copolymers (B) -2 and (B) -3) Synthesis was carried out in the same manner as described above except that the mixing ratio of the monomers and the amount of catalyst were changed. The results are shown in Table 1.

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(Synthesis of low molecular weight aromatic vinyl-conjugated diene copolymer (C) -0) Cyclohexane 1000g, tetrahydrofuran (THF) 20g, 1,3-butadiene 150g and styrene 50g in a 2L autoclave with a fully nitrogen-substituted stirrer. Was introduced, and the temperature inside the autoclave was adjusted to 25 ° C. Next, 2.0 g of n-butyllithium was added and polymerized for 15 minutes under high temperature conditions, and it was confirmed that the conversion rate of the monomer was 99%. Then, 1.5 g of 2,6-di-t-butyl-p-cresol was added as an antioxidant. The results are shown in Table 2.

(Synthesis of low molecular weight aromatic vinyl-conjugated diene copolymer (C) -1) Add 200 g of copolymer (C) -0, 300 g of THF, and 10 g of 10% palladium carbon to a pressure-resistant container, replace with nitrogen, and then apply pressure. Is 5.0 kg / cm²The reaction was carried out at 80 ° C. The hydrogenation rate was calculated from the decrease in the spectrum of the unsaturated bond portion of 100 MHz proton NMR measured at a concentration of 15% by weight using carbon tetrachloride as a solvent. The results are shown in Table 2.

(Synthesis of copolymers (C) -2 to (C) -5) Synthesis was carried out in the same manner as described above except that the monomer charging ratio, the amount of catalyst, the hydrogen pressure, etc. were changed. The results are shown in Table 2.

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Examples 1 to 5 and Comparative Examples 1 to 5 The various chemicals used in Examples and Comparative Examples will be described below. Halide of copolymer of isobutylene and p-methylstyrene: Exxpro 90-10 brominated butyl rubber manufactured by Exxon Chemical Co., Ltd .: Bromobutyl 2255 carbon black manufactured by Exxon Chemical Co., Ltd .: Show manufactured by Showa Cabot Corporation Black N110 (N₂SA: 143m²/ g) Silica: Ultrasil VN3 manufactured by Degussa (nitrogen adsorption specific surface area 210 m)²/ g) Silane coupling agent: Si69 softener manufactured by Degussa Co., Ltd .: Diana process manufactured by Idemitsu Kosan Co., Ltd. AH-16 Stear acid: Zinc oxide made by Nippon Oil &amp; Fat Co., Ltd .: Mitsui Metal Mining Co., Ltd. Zinc Oxide No. 2 Sulfur: Powdered Sulfur Vulcanization Accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .1: Noxeller NS Vulcanization Accelerator manufactured by Ouchi Shinko Chemical Industry Co., Ltd. 2: Made by Ouchi Shinko Chemical Industry Co., Ltd. Noxeller D

Various test rubber compositions were obtained by kneading and blending according to the blending contents shown in Table 3. These formulations were press vulcanized at 170 ° C. for 20 minutes to obtain vulcanized products, which were tested for the properties shown below.

The evaluation of the vulcanized rubber will be described below. (Wet grip performance) A tire having a tread made of the rubber composition was produced. The road surface was watered with a sprinkler, and the actual vehicle was run using the prepared tires on a test course on a wet asphalt road surface. The test driver evaluated the stability of the control during steering at that time, and comparative example 1 was set as 100 and displayed as an index. The larger the value, the greater the wet grip performance, indicating that it is superior.

(Abrasion test) The tire was used to run 20 laps on the test course, the depth of the groove before and after the run was measured, and the index was displayed with Comparative Example 1 as 100. The larger the value, the greater the wear resistance and the better.

(Bleed resistance) The surface of the tire was observed, and the degree of bleeding of oily substances was visually judged. : No bleed : Slightly bleed ×: Severe bleed Table 3 shows the evaluation results obtained from the above tests.

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