JP2018002904A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition having excellent high-temperature grip performance while securing excellent wear resistance.SOLUTION: A rubber composition contains a rubber component containing a styrene-butadiene rubber of 10-100 mass%, and a styrene acrylic resin with an acid value of 30-100 mgKOH/g and a glass transition temperature of at 62-83°C.SELECTED DRAWING: None

Description

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

  A rubber composition for tire treads, particularly a rubber composition for treads of high-performance tires, is required to have excellent high temperature grip.

  Styrene acrylic resin has a high complex elastic modulus (G *) at a high temperature (for example, 100 ° C.), and high temperature grip performance is improved by blending with a 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, mixing with plasticizers and other resins have been taken, but since the compatibility with SBR is inherently poor, the entanglement between the SBR and the resin is sufficient. Moreover, sufficient high temperature grip performance is not obtained.

  Patent Document 1 discloses a pneumatic tire in which initial grip performance, grip performance during running, and wear resistance are improved in a well-balanced manner by using a tire having a tread composed of a rubber composition for a tread containing an acrylic resin. Although a tire is described, compatibility with SBR is not considered.

JP 2006-037532 A

  An object of this invention is to provide the rubber composition excellent in high temperature grip performance, ensuring favorable abrasion resistance.

  The present invention relates to a rubber composition containing a rubber component containing 10 to 100% by mass of a 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 .

Furthermore, it is preferable to contain 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.

  Furthermore, 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 in compatibility in the kneading process, but also can improve high temperature grip performance while ensuring the wear resistance of the rubber composition. This is because the styrene-acrylic resin that bleeds during running and the SBR in the rubber residue attached to the tire are familiar, so the G * of the rubber residue increases, ensuring high wear resistance and improving high-temperature grip performance. It is considered a thing.

  The styrene acrylic resin is a copolymer having a (meth) acrylic component and a component derived from styrene as constituent elements, and among these, the solventless styrene acrylic resin is used because the effects of the present invention can be obtained better. preferable. Solvent-free acrylic resin is a high-temperature continuous polymerization method (high-temperature continuous mass polymerization method) (U.S. Pat. No. 4,414,370) without using polymerization initiators, chain transfer agents, organic solvents and the like as auxiliary materials as much as possible. Description, Japanese Patent Application Laid-Open No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Application Laid-Open No. 1-313522, US Pat. No. 5,010,166, Toa Gosei Research Annual Report TREND 2000 No. 3 p42- Styrene acrylic resin synthesized by the method described in 45). In the present specification, (meth) acryl means methacryl and acryl.

  The styrene acrylic resin preferably contains substantially no polymerization initiator, chain transfer agent, organic solvent, or the like, which is a secondary raw material, 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) acryl 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. (Meth) acrylic acid is a generic 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 malee group, an epoxy group, and a silanol group. A carboxyl group is preferred because the resin has strong self-aggregation properties and can be hydrogen bonded or loosely bonded to 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. When the acid value is less than 30 mgKOH / g, the high temperature grip performance tends to be insufficient. Moreover, the acid value of a styrene acrylic resin is 100 mgKOH / g or less, 90 mgKOH / g or less is preferable and 80 mgKOH / g or less is more preferable. When an acid value exceeds 100 mgKOH / g, there exists a tendency for the effect of this invention to become difficult to be acquired. The acid value of the styrene acrylic resin in this specification is the amount of potassium hydroxide required to neutralize the acid contained in 1 g of the resin, expressed in milligrams. The potentiometric titration method (JIS K 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. When Tg is less than 62 ° C., the high temperature grip performance tends to be insufficient. Moreover, Tg of a styrene acrylic resin is 83 degrees C or less, 81 degrees C or less is preferable and 79 degrees C or less is more preferable. When Tg exceeds 83 ° C., the effect of the present invention tends to be difficult to obtain. In addition, the glass transition temperature of the styrene acrylic resin in this specification is a value measured by performing differential scanning calorimetry (DSC) in accordance with JIS K 7121 under the condition of a heating rate of 10 ° C./min.

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, from the viewpoint of self-aggregation property due to the polar group. .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, from the viewpoint of compatibility with SBR, and 11.1 (cal / Cm ³ ) ^1/2 or less is more preferable. In addition, SP value in this specification means the solubility parameter (Solubility Parameter) computed by the Hoy method based on the structure of a compound. The Hoy method is a calculation method described in, for example, 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. When the content is less than 1 part by mass, the effect of the present invention tends to be insufficient. Moreover, 10 mass parts or less are preferable and, as for content of a styrene acrylic resin, 8 mass parts or less are more preferable. When the content exceeds 10 parts by mass, dispersibility in SBR deteriorates, and wear resistance and initial running grip performance (road surface unevenness followability before the tire warms) tend to deteriorate.

  Styrene butadiene rubber (SBR) is not particularly limited, and examples thereof include emulsion polymerization SBR (E-SBR), solution polymerization SBR (S-SBR), and the like, whether oil-extended or not oil-extended. Good. Of these, oil-extended and high-molecular weight SBR is preferable from the viewpoint of grip performance. Further, terminal-modified S-SBR and main chain-modified S-SBR with enhanced interaction force with the filler can also be used. These SBRs may be used alone or in combination of two or more.

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 from the viewpoint of grip performance. Also, if the styrene content is too high, the styrene group is adjacent, the polymer becomes too hard, the cross-linking tends to be uneven, the blowability at high temperature running may be deteriorated, and the temperature dependency increases, Since the performance change with respect to the temperature change becomes large and there is a tendency that the stable grip performance during running tends not to be obtained well, it is preferably 60% by mass or less, more preferably 50% by mass or less, and 40% by mass or less. Further preferred. In the present specification, the styrene content of SBR is calculated by ¹ H-NMR measurement.

  The vinyl content of SBR is preferably 10% or more, more preferably 15% or more, from the viewpoint of the hardness (Hs) of the rubber composition and grip performance. Moreover, from a viewpoint of grip performance, EB (durability), and abrasion resistance performance, 90% or less is preferable, 80% or less is more preferable, 70% or less is further more preferable, and 60% or less is especially preferable. In addition, in this specification, the vinyl content (1,2-bond butadiene unit amount) of SBR can be measured by an infrared absorption spectrum analysis method.

  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 the present specification, the glass transition temperature of SBR is a value measured by performing differential scanning calorimetry (DSC) in accordance with JIS K 7121 under the condition of a heating rate of 10 ° C./min.

  The weight average molecular weight (Mw) of SBR is preferably 700,000 or more, more preferably 900,000 or more, and further preferably 1,000,000 or more from the viewpoint of grip performance and blowability. Further, from the viewpoint of blowability, that is, filler dispersibility and cross-linking uniformity, the weight average molecular weight is preferably 2 million or less, and more preferably 1.8 million or less. In addition, in this specification, the weight average molecular weight of SBR is gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTPORE manufactured by Tosoh Corporation). It can be determined 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, preferably 40% by mass or more, and more preferably 50% by mass or more, because sufficient grip performance can be obtained. When it is set as a high performance tire, 80 mass% or more is especially preferable, and 100 mass% is preferable from a viewpoint of grip performance. In addition, when using 2 or more types of SBR together, let the total content of all the SBR be content of SBR in the rubber component of this invention.

  The rubber component may contain a rubber component other than SBR. Rubber components other than SBR include isoprene-based rubbers including natural rubber (NR) and polyisoprene rubber (IR), butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber ( And diene rubber components such as NBR) and butyl rubber. These rubber components may be used alone or in combination of two or more in addition to SBR. Especially, it is preferable to contain SBR and BR from a viewpoint of the balance of low fuel consumption performance, abrasion resistance performance, durability, and grip performance.

  The BR is not particularly limited. For example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B having high cis content, such as BR150B, and BR1250H manufactured by Nippon Zeon Co., Ltd. BR, which contains 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, and the like can be used. These BR may use 1 type and may use 2 or more types together. Of these, BR (rare earth BR) synthesized using a rare earth element-based catalyst is preferable from the viewpoint of low fuel consumption performance and wear resistance performance.

  The rare earth BR is a butadiene rubber synthesized using a rare earth element-based catalyst, and has a characteristic that the cis content is high and the vinyl content is low. As the rare earth BR, those common in tire production can be used.

  As the rare earth element-based catalyst used for the synthesis of the rare earth-based BR, known catalysts can be used, for example, a lanthanum series rare earth element compound, an organoaluminum compound, an aluminoxane, a halogen-containing compound, and a catalyst containing a Lewis base as necessary. Etc. 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 compounds include halides, carboxylates, alcoholates, thioalcolates, amides, and the like of rare earth metals having an atomic number of 57 to 71. Among these, the Nd-based catalyst is preferable in that a 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 (wherein R ^a , R ^b and R ^c are the same or different and represent hydrogen or a hydrocarbon group having 1 to 8 carbon atoms). Things can be used. Examples of the aluminoxane include a chain aluminoxane and a cyclic aluminoxane. Examples of the halogen-containing compound include AlX _k R ^d _3-k (wherein X is halogen, R ^d is an alkyl group having 1 to 20 carbon atoms, aryl group or aralkyl group, k is 1, 1.5, 2 or 3). Aluminum halides represented by: strontium halides such as Me ₃ SrCl, Me ₂ SrCl ₂ , MeSrHCl ₂ , MeSrCl ₃ ; metal halides such as silicon tetrachloride, tin tetrachloride, titanium tetrachloride, etc. . The Lewis base is used for complexing a lanthanum series rare earth element compound, and acetylacetone, ketone, alcohol and the like are preferably used.

  The rare earth element-based catalyst may 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 may be silica, magnesia, magnesium chloride, etc. It may be used by being supported on an appropriate 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.

  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 from the viewpoint of durability and wear resistance.

  The vinyl content of the rare earth BR is preferably 1.8% by mass or less, more preferably 1.5% by mass or less, still more preferably 1.0% by mass or less, from the viewpoint of durability and wear resistance. A mass% or less is particularly preferred. In the present specification, the vinyl content (1,2-bond butadiene unit content) and cis content (cis 1,4-bond content) of BR can be measured by infrared absorption spectrum analysis.

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

  In addition to the above components, the rubber composition of the present invention is a compounding agent generally used in the production of rubber compositions, for example, resin components other than the styrene acrylic resin, process oil, liquid polymer, reinforcing filler , A coupling agent, zinc oxide, stearic acid, palmitic acid, lauric acid, fatty acid zinc soap, anti-aging 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. N ₂ SA is preferably 600 m ² / g or less, and more preferably 500 m ² / g or less, from the viewpoint of ensuring good filler dispersibility. Incidentally, N ₂ SA of the carbon black in the present specification, JIS K 6217-2: a value determined by the BET method in compliance with 2001.

  In the case of containing carbon black, the content with respect to 100 parts by mass of the rubber component is preferably 5 parts by mass or more and more preferably 7 parts by mass or more from the viewpoints of preventing ultraviolet cracks and wear resistance. The preferred carbon black content varies depending on the tire member used and the grip performance, wear resistance, and fuel efficiency expected of the tire. In the case of a tire that ensures wet grip performance with silica, such as a tread portion of a general-purpose tire, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably 5 to 30 parts by mass. In addition, in the case of a tire that ensures dry grip performance and wear resistance performance with carbon black, such as a tread portion of a high-performance tire, 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, and talc. These white fillers can be used alone or in combination of two or more. It can also be used in combination. Silica is preferred because of its excellent wear resistance, durability, wet grip performance and low fuel consumption performance.

The BET specific surface area of silica is preferably 70 to 300 m ² / g, more preferably 80 to 280 m ² / g, and still more preferably 90 to 250 m ² / g, from the viewpoints of wear resistance performance, wet grip performance and workability. Incidentally, N ₂ SA of the silica in this specification is a value measured by the BET method in accordance with ASTM D3037-81.

  In the case of containing silica, the content with respect to 100 parts by mass of the rubber component is preferably 40 parts by mass or more and more preferably 50 parts by mass or more from the viewpoint of wet grip performance. Further, the content of silica is preferably 150 parts by mass or less, and more preferably 140 parts by mass or less, from the viewpoint of ensuring workability and fracture resistance (TB) that suppresses shrinkage associated with cooling after vulcanization.

  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. As for content with respect to 100 mass parts of silica in the case of containing a coupling agent, 6-8 mass parts is preferable.

  In addition, the rubber composition of the present invention preferably contains a sulfur-containing compound having an alkoxysilyl group, and in combination with a styrene acrylic resin, the grip performance can be further improved. It is more preferable to contain a sulfur-containing compound having 2 or more. This is because a pseudo-crosslink is formed in the rubber composition by hydrogen bonding between the carboxyl group of the styrene acrylic resin and the alkoxy group of the sulfur-containing compound having two or more alkoxysilyl groups to increase the molecular weight. it is conceivable that. That is, since a styrene acrylic resin having many carboxyl groups and a high acid value is easily increased in molecular weight by a sulfur-containing compound having two or more alkoxysilyl groups, a sulfur having a high acid value styrene acrylic resin and two or more alkoxysilyl groups. It is considered that the effect of the present invention can be more effectively exhibited by using the containing 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, the alkoxysilyl group may have different alkoxy groups, or may have different alkoxy groups. The alkoxy groups 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.

  The content with respect to 100 parts by mass of the rubber component in the case of containing a sulfur-containing compound having two or more alkoxysilyl groups is because the effect of containing a 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. In addition, the content of the sulfur-containing compound having two or more alkoxysilyl groups is preferably determined according to the content of silica when serving as a silane coupling agent, and is coupled to 100 parts by mass of the silica described above. It is preferable to be included in the content of the agent.

  The rubber composition of the present invention can be produced by a general method. For example, in a known kneader used in a general rubber industry such as a Banbury mixer, a kneader, and an open roll, after kneading components other than the crosslinking agent and the vulcanization accelerator among the above components, Further, it can be produced by a method of adding a crosslinking agent and a vulcanization accelerator, kneading and then vulcanizing.

  The rubber composition of the present invention can be used for applications that require gripping force, that is, tires, shoe sole rubber, industrial belts, butyl frame rubber, packing, seismic isolation rubber, medicine plugs, etc. It is suitable for treads for industrial belts and pneumatic tires, and particularly suitable for cap treads of high-performance tires.

  The pneumatic tire is manufactured by a normal method using the rubber composition. That is, the rubber composition containing the above components is extruded in accordance with the shape of the tread at an unvulcanized stage and molded together with other tire members on a tire molding machine by a normal method. Form a vulcanized tire. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

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

  The present invention will be specifically described based on examples, but the present invention is not construed as being limited to these examples.

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 extended, styrene content: 27 mass%, vinyl content: 58%, Tg: -27 ° C., weight average molecular weight: 720,000)
Modified SBR2: Prepared by a method for producing modified SBR2 described later (37.5 parts of oil extended, styrene content: 41% by mass, vinyl content: 40%, Tg: −29 ° C., weight average molecular weight: 1.19 million)
BR: CB25 manufactured by LANXESS Corporation (high-cis BR synthesized using Nd-based catalyst, Tg: -110 ° C)
Isoprene rubber: TSR20 (natural rubber)
CB1: HP180 manufactured by Orion (N ₂ SA: 175 m ² / g)
CB2: HP160 manufactured by Orion (N ₂ SA: 153 m ² / g)
CB3: Show Black N110 (N ₂ SA: 142 m ² / g) manufactured by Cabot Japan
Silica: ULTRASIL VN3 (N ₂ SA: 175 m 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 K.K.
Styrene acrylic resin 1: ARUFON UC-3120 manufactured by Toagosei 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 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (carboxyl group-containing), 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 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), 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 (solvent-free styrene acrylic resin (carboxyl group-containing), manufactured by Toagosei Co., Ltd., 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 Toagosei Co., Ltd. (solvent-free styrene acrylic resin (carboxyl group-containing), 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 (solvent-free styrene acrylic resin (carboxyl group-containing), manufactured by Toagosei Co., Ltd., 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 (solvent-free styrene acrylic resin (carboxyl group-containing), manufactured by Toagosei Co., Ltd., 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 Toagosei 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 (solvent-free all-acrylic resin (carboxyl group-containing), manufactured by Toagosei Co., Ltd., 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 (solvent-free all-acrylic resin (carboxyl group-containing), manufactured by Toagosei Co., Ltd., purity: 98% by mass or more, Tg: 65 ° C., acid value: 74 mgKOH / g, SP value: 11.0 (cal / cm ³ ) ^1/2 , Mw: 10,000)
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 Shinsei Chemical Co., Ltd.
Plasticizer 1: TOP (manufactured by Daihachi Chemical Industry Co., Ltd.) (Tris (2-ethylhexyl) phosphate, freezing point: -72 ° C, Mw: 435, flash point: 204 ° C)
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: VIVETEC400 (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: Colesin manufactured by BASF (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: 10,000) manufactured by Kuraray Co., Ltd.
Zinc oxide: Silver candy R made by Toho Zinc Co., Ltd.
Stearic acid: Stearic acid manufactured by NOF Corporation 椿 Sulfur: HK-200-5 manufactured by Hosoi Chemical Co., Ltd. (oil content 5% by mass)
Vulcanization accelerator 1: Noxeller NS-G (TBBS, N-tert-butyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Noxeller D (DPG, 1,3-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator 3: Noxeller ZTC (zinc dibenzyldithiocarbamate) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(1) Production method of modified SBR1 Production of terminal modifier 1 Under nitrogen atmosphere, 23.6 g of 3- (N, N-dimethylamino) propyltrimethoxysilane (manufactured by Amax Co.) was placed in a 100 ml volumetric flask, and Anhydrous hexane (manufactured by Kanto Chemical Co., Inc.) was added to make a total volume of 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 30 L pressure-resistant vessel sufficiently substituted with nitrogen, and the temperature was raised to 40 ° C. Next, 10 ml of 1.6 M butyl lithium (manufactured by Kanto Chemical Co., Inc.) was added, and the mixture was heated to 50 ° C. and stirred for 3 hours. Next, 11 ml of terminal modifier 1 was added and 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 put into a stainless steel container containing 18 L of methanol to collect aggregates. The obtained aggregate was dried under reduced pressure for 24 hours to obtain 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 Production of terminal modifier 2 In a nitrogen atmosphere, 20.8 g of 3- (N, N-dimethylamino) propyltrimethoxysilane (manufactured by Amax Co.) was placed in a 250 ml volumetric flask, and Anhydrous hexane (manufactured by Kanto Chemical Co., Inc.) was added to make a total volume of 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 30 L pressure vessel sufficiently substituted with nitrogen, and the temperature was raised to 40 ° C. . Next, after adding 1.8 ml of 1.6M butyl lithium (manufactured by Kanto Chemical Co., Inc.), the temperature was raised to 50 ° C. and stirred for 3 hours. Next, 4.1 ml of terminal modifier 2 was added and stirred for 30 minutes. After adding 15 ml of methanol and 0.1 g of 2,6-tert-butyl-p-cresol (manufactured by Ouchi Shinsei Chemical Co., Ltd.) to the reaction solution, 1200 g of TDAE was added and stirred for 10 minutes. Thereafter, the aggregate was recovered from the polymer solution by a 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, using a 1.7 L closed Banbury mixer, kneading chemicals other than sulfur and vulcanization accelerator at a discharge temperature of 170 ° C. for 5 minutes, kneading I got a thing. In the silica compounding formulations in Tables 1 and 2, the obtained kneaded material was kneaded again by the Banbury mixer at a discharge temperature of 150 ° C. for 4 minutes (remill). Next, using a biaxial open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded material, and kneaded for 4 minutes until reaching 105 ° C. to obtain an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition was molded into a tire tread shape, bonded together with other tire members on a tire molding machine, vulcanized at 170 ° C. for 12 minutes, and a test tire (tire size: 215). / 45R17). The following evaluation was performed about the obtained tire for a test.

High-temperature grip performance A test tire was mounted on a 2000 cc domestic FR vehicle, and the vehicle was run for 10 laps on a dry asphalt road test course. 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 index was displayed as a reference comparative example of 100. The larger the value, the smaller the decrease in grip performance during and late driving on the dry road surface, and the better the stable grip performance (high temperature grip performance) during driving and late driving can be obtained. To do. The reference comparative examples in Tables 1 and 2 were set as Comparative Example 1, and the reference comparative examples in Tables 3 and 4 were set as Comparative Example 13.

Abrasion resistance The test tire was mounted on a 2000 cc domestic FR vehicle, and the vehicle was run on a dry asphalt road test course. The remaining groove amount of the tire tread rubber at that time was measured (7.0 mm when new), and the index was displayed with the remaining groove amount of the reference comparative example being 100 (wear resistance index). The larger the value, the higher the wear resistance, and the performance target value is 105 or more. The results in Tables 1 and 2 are based on Comparative Example 1 as the reference comparative example, and the results in Tables 3 and 4 are based on Comparative Example 13 as the reference comparative example.

  From the results of Tables 1 to 4, it is understood 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 (4)

A rubber composition comprising 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 according to claim 1, wherein the styrene acrylic resin has an SP value of 9.5 to 11.5 (cal / cm ³ ) ^1/2 . 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 per 100 parts by mass of the rubber component. Furthermore, the rubber composition of any one of Claims 1-3 containing the sulfur containing compound which has 2 or more of alkoxy silyl groups.