JP6834195B2 - Rubber composition - Google Patents

Description

The present invention relates to a rubber composition containing a rubber component containing styrene-butadiene rubber and a predetermined styrene acrylic resin.

Rubber compositions for tire treads, especially rubber compositions for treads of high-performance tires, are required to have excellent high-temperature grip.

The styrene acrylic resin has a high complex elastic modulus (G *) at a high temperature (for example, 100 ° C.), and the high temperature grip performance is improved by blending it with the rubber composition. However, the conventional styrene acrylic resin has a problem of poor compatibility with styrene butadiene rubber (SBR). Therefore, measures such as increasing the number of kneading, fine pulverization, and mixing with plasticizers and other resins have been taken, but since the compatibility with SBR is essentially poor, the entanglement between SBR and the resin is sufficient. Not enough high temperature grip performance is obtained.

Patent Document 1 states that a tire having a tread made of a rubber composition for tread containing an acrylic resin has improved initial grip performance, grip performance during running, and wear resistance in a well-balanced manner. Tires are listed, but compatibility with SBR is not considered.

Japanese Unexamined Patent Publication No. 2016-037532

An object of the present invention is to provide a rubber composition having excellent high temperature grip performance while ensuring good wear resistance.

The present invention relates to a rubber composition containing a rubber component containing 10 to 100% by mass of styrene-butadiene rubber and a styrene acrylic resin having an acid value of 30 to 100 mgKOH / g and a glass transition temperature of 62 to 83 ° C.

The SP value of the styrene acrylic resin is preferably ^{9.5 to 11.5 (cal / cm 3} ) ^1/2.

Further, it is preferable that 5 parts by mass or more of carbon black having ^{a nitrogen adsorption specific surface area of 151 m 2} / g or more is contained with respect to 100 parts by mass of the rubber component.

Further, it is preferable to contain a sulfur-containing compound having two or more alkoxysilyl groups.

The rubber composition of the present invention containing a rubber component containing styrene-butadiene rubber and a predetermined styrene acrylic resin is excellent in high-temperature grip performance while ensuring good wear resistance.

The rubber composition of the present invention contains a rubber component containing 10 to 100% by mass of styrene-butadiene rubber, and a styrene acrylic resin having an acid value of 30 to 100 mgKOH / g and a glass transition temperature of 62 to 83 ° C.

The rubber composition of the present invention contains a styrene acrylic resin having an acid value of 30 to 100 mgKOH / g and a glass transition temperature of 62 to 83 ° C. This styrene acrylic resin is excellent in compatibility with SBR and not only excellent in compatibility in the kneading process, but also can improve high temperature grip performance while ensuring wear resistance of the rubber composition. This is because the styrene-acrylic resin that bleeds during running and the SBR in the rubber residue adhering to the tire are well-adapted, so the G * of the rubber residue increases, and the high-temperature grip performance improves while ensuring wear resistance. It is considered to be.

The styrene acrylic resin is a copolymer containing a (meth) acrylic component and a component derived from styrene as constituent elements, and among them, the solvent-free styrene acrylic resin is used because the effect of the present invention can be obtained better. preferable. The solvent-free acrylic resin uses a high-temperature continuous polymerization method (high-temperature continuous lump polymerization method) (US Pat. No. 4,414,370) without using a polymerization initiator, a chain transfer agent, an organic solvent, etc. as auxiliary raw materials as much as possible. Specification, Japanese Patent Application Laid-Open No. 59-6207, Japanese Patent Application Laid-Open No. 5-58805, Japanese Patent Application Laid-Open No. 1-313522, US Pat. No. 5,010,166, Toa Synthesis Annual Report TRUE 2000 No. 3 p42- It is a styrene acrylic resin synthesized by the method described in 45 etc.). In addition, in this specification, (meth) acrylic means methacrylic and acrylic.

The styrene acrylic resin preferably does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, etc., which are auxiliary raw materials, and the purity of the styrene acrylic resin is preferably 95% by mass or more, more preferably 97% by mass or more. ..

Examples of the (meth) acrylic component constituting the styrene acrylic resin include (meth) acrylic acid, (meth) acrylic acid ester (alkyl ester, aryl ester, aralkyl ester, etc.), (meth) acrylamide, and (meth). Examples include (meth) acrylic acid derivatives such as acrylamide derivatives. In addition, (meth) acrylic acid is a general term for acrylic acid and methacrylic acid.

Examples of the styrene acrylic resin include those having a modifying group such as a hydroxyl group, a carboxyl group, a maleine group, an epoxy group and a silanol group. A carboxyl group is preferable because the resin has a strong self-aggregating property and can form a hydrogen bond or a loose bond with a sulfur-containing compound having an alkoxysilyl group.

The acid value of the styrene acrylic resin is 30 mgKOH / g or more, preferably 35 mgKOH / g or more, and more preferably 40 mgKOH / g or more. If the acid value is less than 30 mgKOH / g, the high temperature grip performance tends to be insufficient. The acid value of the styrene acrylic resin is 100 mgKOH / g or less, preferably 90 mgKOH / g or less, and more preferably 80 mgKOH / g or less. When the acid value exceeds 100 mgKOH / g, it tends to be difficult to obtain the effects of the present invention. The acid value of the styrene acrylic resin in the present specification represents the amount of potassium hydroxide required to neutralize the acid contained in 1 g of the resin in milligrams, and is represented by the potential difference dropping method (JIS K). It is a value measured by 0070: 1992).

The glass transition temperature (Tg) of the styrene acrylic resin is 62 ° C. or higher, preferably 64 ° C. or higher, and more preferably 66 ° C. or higher. If the Tg is less than 62 ° C, the high temperature grip performance tends to be insufficient. The Tg of the styrene acrylic resin is 83 ° C. or lower, preferably 81 ° C. or lower, and more preferably 79 ° C. or lower. When Tg exceeds 83 ° C., it tends to be difficult to obtain the effect of the present invention. The glass transition temperature of the styrene acrylic resin in the present specification is a value measured by differential scanning calorimetry (DSC) under the condition of a heating rate of 10 ° C./min according to JIS K 7121.

^{The SP value of the styrene acrylic resin is preferably 9.5 (cal / cm 3} ) ^1/2 or more, preferably 9.7 (cal / cm ³ ) ^1/2 or more, preferably 9 from the viewpoint of self-aggregation due to polar groups. 9.9 (cal / cm ³ ) ^1/2 or more is more preferable. ^{The SP value is preferably 11.5 (cal / cm 3} ) ^1/2 or less, preferably 11.3 (cal / cm ³ ) ^1/2 or less, and 11.1 (cal / cm 3) 1/2 or less from the viewpoint of compatibility with SBR. / Cm ³ ) ^1/2 or less is more preferable. The SP value in the present specification means a solubility parameter calculated by the Hoy method based on the structure of the compound. The Hoy method is, for example, a calculation method described in KLHoy “Table of Solubility Parameters”, Solvent and Coatings Materials Research and Development Department, Union Carbites Corp. (1985).

The content of the styrene acrylic resin with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, and more preferably 2 parts by mass or more. If the content is less than 1 part by mass, the effect of the present invention tends to be insufficient. The content of the styrene acrylic resin is preferably 10 parts by mass or less, more preferably 8 parts by mass or less. When the content exceeds 10 parts by mass, the dispersibility in the SBR tends to deteriorate, and the wear resistance and the initial grip performance of running (the ability to follow the road surface unevenness before the tire warms up) tend to deteriorate.

The styrene-butadiene rubber (SBR) is not particularly limited, and examples thereof include emulsion polymerization SBR (E-SBR) and solution polymerization SBR (S-SBR), regardless of whether they are oil-expanded or not. Good. Of these, oil-extended and high-molecular-weight SBR is preferable from the viewpoint of grip performance. In addition, end-modified S-SBR having enhanced interaction with the filler and main chain-modified S-SBR can also be used. One type of these SBRs may be used, or two or more types may be used in combination.

From the viewpoint of grip performance, the styrene content of SBR is preferably 12% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, and particularly preferably 30% by mass or more. Further, if the styrene content is too high, the styrene groups are adjacent to each other, the polymer becomes too hard, the cross-linking tends to be non-uniform, the blow property during high temperature running may be deteriorated, and the temperature dependence is increased. 60% by mass or less is preferable, 50% by mass or less is more preferable, and 40% by mass or less is preferable, because the performance change with respect to the temperature change becomes large and stable grip performance during running tends not to be obtained well. More preferred. In this specification, the styrene content of SBR is ^{calculated by 1 1} H-NMR measurement.

The vinyl content of SBR is preferably 10% or more, more preferably 15% or more, from the viewpoint of hardness (Hs) and grip performance of the rubber composition. Further, from the viewpoint of grip performance, EB (durability), and wear resistance performance, 90% or less is preferable, 80% or less is more preferable, 70% or less is further preferable, and 60% or less is particularly preferable. In the present specification, the vinyl content of SBR (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectroscopy.

SBR also preferably has a glass transition temperature (Tg) of −70 ° C. or higher, more preferably −40 ° C. or higher. The Tg is preferably 10 ° C. or lower, and more preferably 5 ° C. or lower from the viewpoint of preventing embrittlement cracks in the temperate winter season. In this specification, the glass transition temperature of SBR is a value measured by differential scanning calorimetry (DSC) under the condition of a heating rate of 10 ° C./min according to JIS K 7121.

The weight average molecular weight (Mw) of SBR is preferably 700,000 or more, more preferably 900,000 or more, still more preferably 1 million or more, from the viewpoint of grip performance and blowability. Further, from the viewpoint of blowability, that is, filler dispersibility and crosslink uniformity, the weight average molecular weight is preferably 2 million or less, more preferably 1.8 million or less. In the present specification, the weight average molecular weight of SBR is gel permeation chromatography (GPC) (GPC-8000 series manufactured by Toso Co., Ltd., detector: differential refractometer, column: TSKGEL SUPERMALTPORE manufactured by Toso Co., Ltd.). It can be obtained by standard polystyrene conversion based on the measured value by HZ-M).

The content of SBR in the rubber component is 10 to 100% by mass, and 40% by mass or more is preferable, and 50% by mass or more is more preferable, because sufficient grip performance can be obtained. In the case of a high-performance tire, 80% by mass or more is particularly preferable, and 100% by mass is preferable from the viewpoint of grip performance. When two or more types of SBR are used in combination, the total content of all SBR is defined as the content of SBR in the rubber component of the present invention.

The rubber component may contain a rubber component other than SBR. Rubber components other than SBR include isoprene rubber containing natural rubber (NR) and polyisoprene rubber (IR), butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber ( Examples include diene rubber components such as NBR) and butyl rubber. In addition to SBR, these rubber components may be used alone or in combination of two or more. Among them, it is preferable to contain SBR and BR from the viewpoint of the balance between fuel efficiency, wear resistance, durability and grip performance.

The BR is not particularly limited, and for example, BR1220 manufactured by Nippon Zeon Corporation, BR130B and BR150B manufactured by Ube Industries, Ltd., and other BRs having a high cis content, and BR1250H manufactured by Nippon Zeon Corporation, etc. are modified. BR, BR containing syndiotactic polybutadiene crystals such as VCR412 and VCR617 manufactured by Ube Industries, Ltd., BR synthesized using a rare earth element-based catalyst such as BUNACB25 manufactured by LANXESS Co., Ltd. can be used. One type of these BRs may be used, or two or more types may be used in combination. Among them, BR (rare earth element BR) synthesized by using a rare earth element catalyst is preferable from the viewpoint of fuel efficiency and wear resistance.

The rare earth-based BR is a butadiene rubber synthesized by using a rare earth element-based catalyst, and has a feature of having a high cis content and a low vinyl content. As the rare earth BR, a general one can be used in tire manufacturing.

Known rare earth element catalysts used in the synthesis of rare earth BRs can be used, for example, lanthanum series rare earth element compounds, organoaluminum compounds, aluminoxanes, halogen-containing compounds, and catalysts containing Lewis bases if necessary. And so on. Among these, an Nd-based catalyst using a neodymium (Nd) -containing compound as the lanthanum-series rare earth element compound is particularly preferable.

Examples of the lanthanum series rare earth element compound include halides, carboxylates, alcoholates, thioalcolates, and amides of rare earth metals having atomic numbers 57 to 71. Above all, the Nd-based catalyst is preferable in that BR having a high cis content and a low vinyl content can be obtained.

The organoaluminum compound is represented by AlR ^a R ^b R ^c (in the formula, R ^a , R ^b , and R ^c represent hydrogen or a hydrocarbon group having 1 to 8 carbon atoms, which are the same or different). You can use things. Examples of the aluminoxane include chain aluminoxane and cyclic aluminoxane. Examples of the halogen-containing compound include AlX _k R ^d _3-k (in the formula, X is halogen, R ^d is an alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, and k is 1, 1.5, 2 or 3). Aluminum halide represented by): _{Strontium halides such as Me 3} SrCl, Me ₂ SrCl ₂ , MeSr HCl ₂ , and MeSrCl ₃ ; metal halides such as silicon tetrachloride, tin tetrachloride, and titanium tetrachloride can be mentioned. .. The Lewis base is used to complex a lanthanum series rare earth element compound, and acetylacetone, a ketone, an alcohol and the like are preferably used.

Rare earth element-based catalysts can be used in the state of being dissolved in an organic solvent (n-hexane, cyclohexane, n-heptane, toluene, xylene, benzene, etc.) during the polymerization of butadiene, or silica, magnesia, magnesium chloride, etc. It may be used by supporting it on a suitable carrier. The polymerization conditions may be either solution polymerization or bulk polymerization, the preferred polymerization temperature is -30 to 150 ° C., and the polymerization pressure may be arbitrarily selected depending on other conditions.

From the viewpoint of durability and wear resistance, the cis 1,4 bond content (cis content) of the rare earth BR is preferably 90% by mass or more, more preferably 93% by mass or more, and more preferably 95% by mass or more.

The vinyl content of the rare earth BR is preferably 1.8% by mass or less, more preferably 1.5% by mass or less, further preferably 1.0% by mass or less, and further preferably 0.8% by mass, from the viewpoint of durability and wear resistance. Mass% or less is particularly preferable. In the present specification, the vinyl content (1,2-bonded butadiene unit amount) and the cis content (cis 1,4 bond content) of BR can be measured by infrared absorption spectroscopy.

When BR is contained, the content of BR in the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, and 20% by mass or more from the viewpoint of wear resistance, grip performance, and fuel efficiency. Is even more preferable. The content is preferably 70% by mass or less, more preferably 60% by mass or less, and preferably 40% by mass or less for tires that require grip performance, from the viewpoints of wear resistance, grip performance, and fuel efficiency.

In addition to the above components, the rubber composition of the present invention contains a compounding agent generally used for producing the rubber composition, for example, a resin component other than the styrene acrylic resin, a process oil, a liquid polymer, and a reinforcing filler. , Coupling agent, zinc oxide, stearic acid, palmitic acid, lauric acid, fatty acid zinc soap, antiaging agent, wax, vulcanizing agent, vulcanization accelerator and the like can be appropriately contained.

The reinforcing filler is not particularly limited, and examples thereof include carbon black and white filler.

The nitrogen adsorption specific surface area (N ₂ ^{SA) of the carbon black is preferably 151 m 2} / g or more, more preferably 155 m ² / g or more, from the viewpoint of grip performance and wear resistance performance. Further, N ₂ ^{SA is preferably 600 m 2} / g or less, more preferably ^{500 m 2} / g or less, from the viewpoint of ensuring good filler dispersibility. The carbon black N ₂ SA in the present specification is a value obtained by the BET method in accordance with JIS K 6217-2: 2001.

When carbon black is contained, the content of the rubber component with respect to 100 parts by mass is preferably 5 parts by mass or more, and more preferably 7 parts by mass or more from the viewpoint of preventing ultraviolet cracks and abrasion resistance. The preferable carbon black content varies depending on the tire member used and the grip performance, wear resistance performance, and fuel efficiency performance expected of the tire. In the case of a tire such as a tread portion of a general-purpose tire whose wet grip performance is ensured by silica, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably 5 to 30 parts by mass. Further, in the case of a tire such as a tread portion of a high-performance tire that secures dry grip performance and wear resistance performance by carbon black, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably 40 to 150 parts by mass.

Examples of the white filler include silica, aluminum hydroxide, magnesium sulfate, zirconium oxide, alumina (aluminum oxide), calcium carbonate, talc, etc., and two or more of these white fillers may be used alone. It can also be used in combination. Silica is preferable because it has excellent wear resistance, durability, wet grip performance, and fuel efficiency.

The BET specific surface area of silica is preferably 70 to 300 m ² / g, more preferably 80 to 280 m ² / g, and even ^{more preferably 90 to 250 m 2} / g, from the viewpoint of wear resistance, wet grip performance and workability. _{The N 2} SA of silica in the present specification is a value measured by the BET method according to ASTM D3037-81.

When silica is contained, the content of the rubber component with respect to 100 parts by mass is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, from the viewpoint of wet grip performance. The silica content is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, from the viewpoint of processability, suppressing shrinkage due to cooling after vulcanization, and ensuring breaking drag (TB).

Examples of the coupling agent include a silane coupling agent and a carbon coupling agent, and a coupling agent conventionally used in the rubber industry can be used. When the coupling agent is contained, the content of silica with respect to 100 parts by mass is preferably 6 to 8 parts by mass.

Further, the rubber composition of the present invention preferably contains a sulfur-containing compound having an alkoxysilyl group, and when used in combination with a styrene acrylic resin, the grip performance can be further improved. Therefore, the alkoxysilyl group It is more preferable to contain a sulfur-containing compound having 2 or more of. This is because the carboxyl group of the styrene acrylic resin and the alkoxy group of the sulfur-containing compound having two or more alkoxysilyl groups are hydrogen-bonded to increase the molecular weight, so that pseudo-crosslinks are formed in the rubber composition. it is conceivable that. That is, since a styrene acrylic resin having many carboxyl groups and a high acid value is likely to have a high molecular weight due to a sulfur-containing compound having two or more alkoxysilyl groups, a styrene acrylic resin having a high acid value and sulfur having two or more alkoxysilyl groups It is considered that the effect of the present invention can be more effectively exerted by using the contained compound in combination.

The alkoxy groups in the sulfur-containing compound having two or more alkoxysilyl groups may be the same or different. That is, it may have a different alkoxy group depending on the alkoxysilyl group, or it may have a different alkoxy group. The alkoxy group in each alkoxysilyl group may be the same or different. Examples of the sulfur-containing compound having two or more alkoxysilyl groups include bis (3-triethoxysilylpropyl) disulfide and bis (3-triethoxysilylpropyl) tetrasulfide.

When a sulfur-containing compound having two or more alkoxysilyl groups is contained, the content of the rubber component with respect to 100 parts by mass is such that the effect of containing the sulfur-containing compound having two or more alkoxysilyl groups is sufficiently exhibited. 0.7 parts by mass or more is preferable, and 0.5 parts by mass or more is more preferable. Further, the content of the sulfur-containing compound having two or more alkoxysilyl groups is preferably determined according to the content of silica when it also functions as a silane coupling agent, and the coupling with respect to 100 parts by mass of silica described above. It is preferably included in the content of the agent.

The rubber composition of the present invention can be produced by a general method. For example, a known kneader used in the general rubber industry such as a Banbury mixer, a kneader, and an open roll is used to knead each of the above components other than the cross-linking agent and the vulcanization accelerator, and then knead the components. , A cross-linking agent and a vulcanization accelerator are added, the mixture is further kneaded, and then vulcanization is performed.

The rubber composition of the present invention can be used for applications requiring grip, that is, tires, sole rubber, industrial belts, butyl frame rubber, packing, seismic isolation rubber, chemical stoppers, etc. Among them, sole rubber. It is suitable for treads of industrial belts and pneumatic tires, and is particularly suitable for cap treads of high-performance tires.

The pneumatic tire is manufactured by a conventional method using the rubber composition. That is, the rubber composition containing the above components is extruded according to the shape of the tread at the unvulcanized stage, and is molded together with other tire members by a normal method on a tire molding machine. Form a vulcanized tire. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

The pneumatic tire can be used for tires for passenger cars, trucks / buses, sports cars, two-wheeled motorcycles, competition vehicles, etc., but is particularly preferably used as a high-performance tire. The high-performance tire in the present invention is a tire having particularly excellent grip performance (particularly, dry grip performance), and is a concept including a competition tire used for a competition vehicle, and the competition tire is a race or the like. It can be suitably applied to competition tires, particularly dry competition tires used on dry road surfaces.

Although the present invention will be specifically described based on Examples, the present invention is not construed as being limited to these.

Various chemicals used in Examples and Comparative Examples will be described.
Modified SBR1: Prepared by the method for producing modified SBR1 described later (non-oil spread, styrene content: 27% by mass, vinyl content: 58%, Tg: -27 ° C., weight average molecular weight: 720,000)
Modified SBR2: Prepared by the method for producing modified SBR2 described later (oil spread 37.5 parts, styrene content: 41% by mass, vinyl content: 40%, Tg: -29 ° C., weight average molecular weight: 1.19 million).
BR: CB25 manufactured by LANXESS Co., Ltd. (Hisys BR synthesized using an Nd catalyst, Tg: -110 ° C.)
Isoprene rubber: TSR20 (natural rubber)
CB1: HP180 manufactured by Orion (N ₂ SA: 175m ² / g)
CB2: HP160 manufactured by Orion (N ₂ SA: ^{153m 2} / g)
CB3: Show Black N110 (N ₂ SA: ^{142m 2} / g) manufactured by Cabot Japan Co., Ltd.
Silica: ULTRASIL VN3 (N ₂ SA: 175m ² / g) manufactured by Evonik Degussa
Alkoxysilyl compound 1: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Alkoxysilyl compound 2: Si75 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa.
Alkoxysilyl compound 3: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive.
Aluminum hydroxide: Heidilite H43 manufactured by Showa Denko KK
Styrene acrylic resin 1: ARUFON UC-3120 manufactured by Toa Synthetic Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 72 ° C., acid value: 74 mgKOH / g, SP value 10.8 (cal / cm ³ ) ^1/2 , Mw: 3400)
Styrene acrylic resin 2: GIR-16 (solvent-free styrene acrylic resin (containing carboxyl group)) manufactured by Toa Synthetic Co., Ltd., purity: 98% by mass or more, Tg: 62 ° C., acid value: 33 mgKOH / g, SP value: 10.7 (cal / cm ³ ) ^1/2 , Mw: 3750)
Styrene acrylic resin 3: GIR-7 (solvent-free styrene acrylic resin (containing carboxyl group)) manufactured by Toa Synthetic Co., Ltd., purity: 98% by mass or more, Tg: 54 ° C., acid value: 72 mgKOH / g, SP value: 10.5 (cal / cm ³ ) ^1/2 , Mw: 8700)
Styrene acrylic resin 4: ARUFON UC-3900 manufactured by Toa Synthetic Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 60 ° C., acid value: 108 mgKOH / g, SP value 11.3 (cal / cm ³ ) ^1/2 , Mw: 4600)
Styrene acrylic resin 5: ARUFON UF-5041 manufactured by Toa Synthetic Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 77 ° C., acid value: 260 mgKOH / g, SP value 11.3 (cal / cm ³ ) ^1/2 , Mw: 7500)
Styrene acrylic resin 6: ARUFON UC-3910 manufactured by Toa Synthetic Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 85 ° C., acid value: 200 mgKOH / g, SP value 11.6 (cal / cm ³ ) ^1/2 , Mw: 8500)
Styrene acrylic resin 7: ARUFON UC-3920 manufactured by Toa Synthetic Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 102 ° C., acid value: 240 mgKOH / g, SP value : 11.9 (cal / cm ³ ) ^1/2 , Mw: 15500)
Styrene acrylic resin 8: ARUFON UH-2170 manufactured by Toa Synthetic Co., Ltd. (solvent-free styrene acrylic resin (containing hydroxyl group), purity: 98% by mass or more, Tg: 60 ° C., acid value: 88 mgKOH / g, SP value: 10.8 (cal / cm ³ ) ^1/2 , Mw: 14000)
Acrylic resin 1: ARUFON UC-3510 manufactured by Toa Synthetic Co., Ltd. (solvent-free all-acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: -50 ° C, acid value: 70 mgKOH / g, SP value 11.0 (cal / cm ³ ) ^1/2 , Mw: 2000)
Acrylic resin 2: ARUFON UC-3000 manufactured by Toa Synthetic Co., Ltd. (solvent-free all-acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 65 ° C., acid value: 74 mgKOH / g, SP value: 11.0 (cal / cm ³ ) ^1/2 , Mw: 10000)
Anti-aging agent 1: Antigen 6C (6PPD, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Anti-aging agent 2: Nocrack 224 (TMQ, 2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Plasticizer 1: TOP (Tris (2-ethylhexyl) phosphate, freezing point: -72 ° C, Mw: 435, flash point: 204 ° C) manufactured by Daihachi Chemical Industry Co., Ltd.
Plasticizer 2: BXA-N (bis (2- (2-butoxyethoxy) ethyl) adipate manufactured by Daihachi Chemical Industry Co., Ltd., freezing point: -19 ° C, Mw: 435, flash point: 207 ° C)
Oil: VIVATEC400 (TDAE oil) manufactured by H & R
Resin 1: YS resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (aromatic terpene resin, softening point: 125 ° C, Tg: 64 ° C)
Resin 2: BASF's koresin (phenolic resin, softening point: 145 ° C, Tg: 98 ° C)
Resin 3: M125 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenated styrene terpene resin, softening point: 125 ° C., Tg: 65)
Liquid SBR: L-SBR-820 (Mw: 10000) manufactured by Kuraray Co., Ltd.
Zinc oxide: Ginmine R manufactured by Toho Zinc Co., Ltd.
Stearic acid: Stearic acid made by NOF Corporation Camellia sulfur: HK-200-5 manufactured by Hosoi Chemical Industry Co., Ltd. (oil content 5% by mass)
Vulcanization Accelerator 1: Noxeller NS-G (TBBS, N-tert-butyl-2-benzothiazil sulfenamide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator 2: Noxeller D (DPG, 1,3-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator 3: Noxeller ZTC (zinc dibenzyldithiocarbamate) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(1) Production method of modified SBR1 Preparation of terminal modifier 1 In a nitrogen atmosphere, add 23.6 g of 3- (N, N-dimethylamino) propyltrimethoxysilane (manufactured by Azumax Co., Ltd.) to a 100 ml volumetric flask, and further. Anhydrous hexane (manufactured by Kanto Kagaku Co., Ltd.) was added to make the total volume 100 ml.
Preparation of Modified SBR1 18 L of n-hexane, 740 g of styrene (manufactured by Kanto Chemical Co., Inc.), 1260 g of butadiene, and 10 mmol of tetramethylethylenediamine were added to a sufficiently nitrogen-substituted 30 L pressure-resistant container, and the temperature was raised to 40 ° C. Next, 10 ml of 1.6 M butyllithium (manufactured by Kanto Chemical Co., Inc.) was added, the temperature was raised to 50 ° C., and the mixture was stirred for 3 hours. Next, 11 ml of terminal denaturant 1 was added, and the mixture was stirred for 30 minutes. After adding 15 ml of methanol and 0.1 g of 2,6-tert-butyl-p-cresol to the reaction solution, the reaction solution was placed in a stainless steel container containing 18 L of methanol to recover the aggregates. The obtained aggregate was dried under reduced pressure for 24 hours to obtain a modified SBR1. The amount of bound styrene was 27% by mass, the amount of vinyl was 58%, Tg: −27 ° C., and Mw was 720,000.

(2) Production method of modified SBR2 Preparation of terminal modifier 2 Nitrogen atmosphere, put 20.8 g of 3- (N, N-dimethylamino) propyltrimethoxysilane (manufactured by Azumax Co., Ltd.) in a 250 ml volumetric flask, and further Anhydrous hexane (manufactured by Kanto Chemical Co., Ltd.) was added to make the total volume 250 ml.
Preparation of Modified SBR2 18 L of n-hexane, 800 g of styrene (manufactured by Kanto Chemical Co., Inc.), 1200 g of butadiene, and 1.1 mmol of tetramethylethylenediamine were added to a sufficiently nitrogen-substituted 30 L pressure-resistant container, and the temperature was raised to 40 ° C. .. Next, 1.8 ml of 1.6 M butyllithium (manufactured by Kanto Chemical Co., Inc.) was added, the temperature was raised to 50 ° C., and the mixture was stirred for 3 hours. Next, 4.1 ml of terminal denaturant 2 was added, and the mixture was stirred for 30 minutes. After adding 15 ml of methanol and 0.1 g of 2,6-tert-butyl-p-cresol (manufactured by Ouchi Shinko Kagaku Co., Ltd.) to the reaction solution, 1200 g of TDAE was added and the mixture was stirred for 10 minutes. Then, the agglomerates were recovered from the polymer solution by steam stripping treatment. The obtained aggregate was dried under reduced pressure for 24 hours to obtain modified SBR2. The amount of bound styrene was 41% by mass, the amount of vinyl was 40%, Tg: −29 ° C., and Mw was 1.19 million.

Examples and Comparative Examples According to the formulation shown in Tables 1 to 4, chemicals other than sulfur and vulcanization accelerator were kneaded at a discharge temperature of 170 ° C. for 5 minutes using a 1.7 L sealed Bunbury mixer, and kneaded. I got something. In the silica-blended formulations shown in Tables 1 and 2, the obtained kneaded product was kneaded again with the Banbury mixer at a discharge temperature of 150 ° C. for 4 minutes (remill). Next, using a twin-screw open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded for 4 minutes until the temperature reached 105 ° C. to obtain an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition is molded into the shape of a tire tread, bonded together with other tire members on a tire molding machine, vulcanized at 170 ° C. for 12 minutes, and tested tire (tire size: 215). / 45R17) was manufactured. The following evaluation was performed on the obtained test tires.

High-temperature grip performance test tires were mounted on a domestic FR vehicle with a displacement of 2000 cc, and the actual vehicle ran 10 laps on a test course on a dry asphalt road surface. At that time, the test driver compared and evaluated the stability of the control during steering of the best lap and the final lap, and the standard comparative example was set as 100 and displayed as an index. The larger the value, the smaller the decrease in grip performance during and after driving on a dry road surface, indicating that stable grip performance (high temperature grip performance) during and after driving can be obtained well, and 105 or more is set as the performance target value. To do. The reference comparison examples of Tables 1 and 2 are referred to as Comparative Example 1, and the reference comparison examples of Tables 3 and 4 are referred to as Comparative Example 13.

Abrasion resistance The above test tires were mounted on a domestic FR vehicle with a displacement of 2000 cc, and the actual vehicle was run on a test course on a dry asphalt road surface. At that time, the amount of remaining groove of the tire tread rubber was measured (7.0 mm when new), and the amount of remaining groove of each standard comparative example was set as 100 and displayed as an index (wear resistance index). The larger the value, the higher the wear resistance, and 105 or more is set as the performance target value. The results of Tables 1 and 2 used Comparative Example 1 as a reference comparative example, and the results of Tables 3 and 4 used Comparative Example 13 as a reference comparative example.

From the results in Tables 1 to 4, it can be seen that the rubber composition of the present invention containing a rubber component containing styrene-butadiene rubber and a predetermined styrene acrylic resin is excellent in high-temperature grip performance while ensuring good wear resistance. ..

Claims (5)

A rubber composition containing a rubber component containing 10 to 100% by mass of styrene-butadiene rubber and a styrene acrylic resin having an acid value of 30 to 100 mgKOH / g and a glass transition temperature of 62 to 83 ° C. The SP value of the styrene acrylic resin is 9.5~11.5 (cal / cm ³⁾ Ri ^1/2 der,
The SP value of Ru solubility parameter der calculated by Hoy method according to claim 1 rubber composition. The rubber composition according to claim 1 or 2, further comprising 5 parts by mass or more of carbon black having ^{a nitrogen adsorption specific surface area of 151 m 2} / g or more with respect to 100 parts by mass of the rubber component. The rubber composition according to any one of claims 1 to 3, further comprising a sulfur-containing compound having two or more alkoxysilyl groups. The rubber composition according to any one of claims 1 to 4, wherein the content of the styrene acrylic resin with respect to 100 parts by mass of the rubber component is 5 parts by mass or more.