JP2016037532A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire with a tread produced using a rubber composition, while securing satisfactory wear resistance, capable of improving grip performance in the initial stage and stable grip performance during running and in the latter stage simultaneously to high dimensions.SOLUTION: Provided is a pneumatic tire with a tread using a rubber composition comprising a rubber component and an acrylic resin in which nitrogen adsorption specific surface area is 0.5 mor higher and glass transition temperature is 0 to 110°C and/or at least one resin selected from an alkylphenol-based resin, a coumarone-indene resin and a terpene phenol resin in which nitrogen adsorption specific surface area is 0.5 mand glass transition temperature is 60°C or higher, in which, to 100 pts.mass of the rubber component, the total content of the acrylic resin, the alkylphenol-based resin, the coumarone-indene resin and the terpene phenol resin is 1 to 100 pts.mass.SELECTED DRAWING: None

Description

The present invention relates to a pneumatic tire having a tread produced using a rubber composition.

It is desired that tire treads maintain excellent handling stability (grip performance) from the beginning of travel to the end of travel. In other words, it is desired to maintain good grip performance during running and late stage as well as excellent initial grip performance, and it is also required to ensure wear resistance that generally tends to contradict grip performance.

Conventionally, for the purpose of improving the initial grip performance, a method of increasing the blending amount of a low softening point resin or a liquid polymer or a method of blending a low-temperature softening agent has been studied, and the tire temperature becomes 60 ° C. or higher. In order to obtain a stable grip performance during traveling, a method of blending a high softening point resin has been studied.

However, when a low softening point resin is blended, although the initial grip performance is improved, there is a problem that the grip performance during running and in the latter stage decreases as the temperature of the tread increases. On the other hand, when a high softening point resin such as coumarone indene resin is blended, there is a problem in that the initial grip performance is greatly reduced although stable grip performance can be obtained during running and in the latter period.

Patent Document 1 discloses a method of combining a low softening point resin and a high softening point resin, which can be considered as a technique for solving these problems, into a rubber composition. However, since the compounding amount of the resin greatly affects the temperature characteristics of the entire rubber, the amount of resin that can be compounded is limited. As a result, even when the low softening point resin and the high softening point resin are used in combination, the initial grip performance and the stable grip performance during running cannot be obtained as much as when each resin is blended alone.

On the other hand, a technology to add a terpene resin or an aromatic resin, which has a structurally good compatibility with rubber and tends to be mixed, has been proposed. Further improvement is demanded in terms of improving grip performance and stable grip performance during and late driving at the same time.

JP 2004-137463 A

The present invention solves the above-mentioned problems and provides a tread produced using a rubber composition capable of simultaneously improving the initial grip performance and the stable grip performance during running / late stage at a high level while ensuring good wear resistance. An object is to provide a pneumatic tire having the same.

The present invention includes a rubber component, an acrylic resin having a nitrogen adsorption specific surface area of 0.5 m ² / g or more and a glass transition temperature of 0 to 110 ° C. and / or a nitrogen adsorption specific surface area of 0.5 m ² / g or more, a glass transition temperature. Containing at least one resin selected from the group consisting of an alkylphenol resin at 60 ° C. or higher, a coumarone indene resin, and a terpene phenol resin, with respect to 100 parts by mass of the rubber component, the acrylic resin, the alkylphenol resin The present invention relates to a pneumatic tire having a tread produced using a rubber composition having a total content of resin, coumarone indene resin and terpene phenol resin of 1 to 100 parts by mass.

It is preferable that the acrylic resin is a solventless acrylic resin.

It is preferable that the acrylic resin is a solventless styrene acrylic resin.

The hydroxyl value or acid value of the acrylic resin, the alkylphenol resin, the coumarone indene resin, and the terpene phenol resin is preferably 15 to 250 mgKOH / g.

The nitrogen adsorption specific surface area of the acrylic resin, the alkylphenol resin, the coumarone indene resin, and the terpene phenol resin is preferably 2 m ² / g or more.

100 parts by mass of the rubber component comprising an inorganic filler consisting of at least one selected from the group consisting of a compound represented by the following formula, magnesium sulfate, and silicon carbide, and having a nitrogen adsorption specific surface area of 5 to 120 m ² / g It is preferable to contain 1-70 mass parts with respect to.
mM · xSiO _y · zH ₂ O
Wherein M is at least one metal selected from the group consisting of Al, Mg, Ti, Ca and Zr, an oxide or hydroxide of the metal, m is an integer of 1 to 5, and x is (An integer of 0 to 10, y is an integer of 2 to 5, and z is an integer of 0 to 10.)

It is preferable that the inorganic filler is aluminum hydroxide.

According to the present invention, at least one selected from the group consisting of a rubber component and a predetermined amount of an acrylic resin having a specific nitrogen adsorption specific surface area and a specific glass transition temperature, an alkylphenol resin, a coumarone indene resin, and a terpene phenol resin. As a pneumatic tire having a tread made using a rubber composition containing two resins, the initial grip performance and the stable grip performance during and after driving (especially on the dry road surface) while ensuring good wear resistance The initial grip performance and the stable grip performance during and after driving are excellent at the same time.

The present invention was produced using a rubber composition containing a predetermined amount of a rubber component and at least one resin selected from the group consisting of a specific acrylic resin, alkylphenol resin, coumarone indene resin and terpene phenol resin. A pneumatic tire having a tread.

In the present invention, the specific acrylic resin is an acrylic resin having a nitrogen adsorption specific surface area of 0.5 m ² / g or more and a glass transition temperature of 0 to 110 ° C.
In the present invention, the specific alkylphenol resin is an alkylphenol resin having a nitrogen adsorption specific surface area of 0.5 m ² / g or more and a glass transition temperature of 60 ° C. or more.
In the present invention, the specific coumarone indene resin is a coumarone indene resin having a nitrogen adsorption specific surface area of 0.5 m ² / g or more and a glass transition temperature of 60 ° C. or more.
In the present invention, the specific terpene phenol resin is a terpene phenol resin having a nitrogen adsorption specific surface area of 0.5 m ² / g or more and a glass transition temperature of 60 ° C. or more.

By using at least one resin selected from the group consisting of an acrylic resin having a specific nitrogen adsorption specific surface area and a specific glass transition temperature, an alkylphenol resin, a coumarone indene resin and a terpene phenol resin as a resin component, Compared to the method of using a low softening point resin and a high softening point resin together, or the method of adding a terpene resin or an aromatic resin with good mixing properties with rubber, the initial stage while ensuring good wear resistance. Grip performance and stable grip performance during and late driving (especially initial grip performance on dry road surface and stable grip performance during and late driving) can be improved at a high level at the same time.

This is because at least one resin selected from the group consisting of acrylic resins, alkylphenol resins, coumarone indene resins and terpene phenol resins having not only a predetermined glass transition temperature but also a relatively large specific surface area is used. Since the dispersibility of the resin in the rubber is greatly increased, it is presumed that the above-mentioned effects are exhibited remarkably.

The rubber composition for a tread constituting the pneumatic tire of the present invention includes a rubber component, a predetermined amount of an acrylic resin having a specific nitrogen adsorption specific surface area and a specific glass transition temperature, an alkylphenol resin, a coumarone indene resin, and a terpene phenol. And at least one resin selected from the group consisting of resins.

Examples of rubber components that can be used in the present invention include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), and ethylene propylene diene rubber ( EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), diene rubber such as butyl rubber (IIR). A rubber component may be used independently and may use 2 or more types together. Of these, NR, BR, and SBR are preferable, and SBR is more preferable because grip performance and wear resistance can be obtained in a well-balanced manner.

The SBR is not particularly limited, and for example, emulsion-polymerized styrene butadiene rubber (E-SBR), solution-polymerized styrene butadiene rubber (S-SBR), process oil extended high molecular weight styrene butadiene rubber, and the like can be used. S-SBR is particularly preferable in that the effect of the present invention is effectively exhibited.

The styrene content of SBR is preferably 20% by mass or more, more preferably 25% by mass or more. When it is less than 20% by mass, sufficient grip performance tends to be not obtained. The styrene content is preferably 60% by mass or less, and more preferably 50% by mass or less. If it exceeds 60% by mass, not only the wear resistance will be lowered, but also the temperature dependency will increase, and the performance change with respect to the temperature change will become large, and stable grip performance during running and late will not be obtained well Tend. In the present invention, the styrene content of SBR is calculated by H ¹ -NMR measurement.

The content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 50% by mass or more, and particularly preferably 60% by mass or more. If it is less than 10% by mass, sufficient heat resistance, grip performance and wear resistance tend to be not obtained. Further, the upper limit of the SBR content is not particularly limited, and may be 100% by mass.

The present invention contains at least one resin selected from the group consisting of an acrylic resin having a specific nitrogen adsorption specific surface area and a specific glass transition temperature, an alkylphenol resin, a coumarone indene resin, and a terpene phenol resin. As a result, while maintaining good wear resistance, initial grip performance and stable grip performance during and late driving (especially initial grip performance on dry road surfaces and stable grip performance during and late driving) are simultaneously increased to a high level. It can be improved.

As the acrylic resin, a solventless acrylic resin can be suitably used in that the effect of the present invention can be obtained satisfactorily.

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- (Meth) acrylic resin (polymer) synthesized by the method described in 45 et al. In the present invention, (meth) acryl means methacryl and acryl.

It is preferable that the acrylic resin does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, or the like, which are auxiliary materials. Moreover, the said acrylic resin has a comparatively narrow composition distribution and molecular weight distribution obtained by continuous polymerization at the point of the effect of this invention.

As described above, the acrylic resin is preferably one that does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, or the like that is a secondary raw material, that is, has a high purity. The purity of the acrylic resin (ratio of the resin contained in the resin) is preferably 95% by mass or more, more preferably 97% by mass or more.

Examples of the monomer component constituting the acrylic resin include (meth) acrylic acid, (meth) acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth) acrylamides, and (meth) acrylamide derivatives. And (meth) acrylic acid derivatives. (Meth) acrylic acid is a general term for acrylic acid and methacrylic acid.

Moreover, as monomer components constituting the acrylic resin, together with (meth) acrylic acid and (meth) acrylic acid derivatives, styrene, α-methylstyrene, vinyl toluene, vinyl naphthalene, divinyl benzene, trivinyl benzene, divinyl naphthalene, etc. Aromatic vinyl may be used.

The acrylic resin may be a resin composed of only a (meth) acrylic component or a resin having components other than the (meth) acrylic component as components, but the effect of the present invention is more effective. From the reason that it can be suitably obtained, a styrene acrylic resin (solvent-free styrene acrylic resin) having a component derived from styrene together with a (meth) acrylic component is preferable.

The acrylic resin may have a hydroxyl group, a carboxyl group, an epoxy group, a silanol group, and the like. Among them, the acrylic resin has a hydroxyl group and a carboxyl group because the effects of the present invention can be more suitably obtained. It is preferable that it has a carboxyl group.

The alkylphenol-based resin is not particularly limited, and is an alkylphenol aldehyde condensation resin obtained by reacting an alkylphenol with an aldehyde such as formaldehyde, acetaldehyde, or furfural with an acid or alkali catalyst; an alkylphenol, and an alkyne such as acetylene; Alkylphenol alkyne condensation resins obtained by reacting these resins with modified resins such as cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resins, aniline, melamine, etc. Alkylphenol resin; and the like. Among these, from the viewpoint of the effect of the present invention, an alkylphenol alkyne condensation resin is preferable, and an alkylphenol acetylene condensation resin is particularly preferable.

Examples of the alkylphenol constituting the alkylphenol-based resin include cresol, xylenol, t-butylphenol, octylphenol, and nonylphenol. Of these, a phenol having a branched alkyl group such as t-butylphenol is preferable, and t-butylphenol is particularly preferable.

The coumarone indene resin is a resin containing coumarone and indene as monomer components constituting the resin skeleton (main chain). In addition to coumarone and indene, monomer components contained in the skeleton include styrene, α-methyl Examples include styrene, phenol, methylindene, vinyltoluene and the like.

The terpene phenol resin is a resin using a terpene compound and a phenol compound as raw materials, and examples of the phenol compound used as a raw material for the terpene phenol resin include phenol, bisphenol A, cresol, and xylenol.

The nitrogen adsorption specific surface area (N ₂ SA) of the acrylic resin, the alkylphenol resin, the coumarone indene resin and the terpene phenol resin is 0.5 m ² / g or more, preferably 1.0 m ² / g or more, More preferably, it is 2.0 m ² / g or more. The upper limit of the _N 2 SA is not particularly limited. In the present invention, the nitrogen adsorption specific surface area of the acrylic resin, alkylphenol resin, coumarone indene resin and terpene phenol resin is determined in accordance with JIS K 6217-2: 2001.

The acrylic resin has a glass transition temperature (Tg) (° C./DSC) of 0 ° C. or higher, preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and still more preferably 50 ° C. or higher. Moreover, this Tg is 110 degrees C or less, Preferably it is 105 degrees C or less, More preferably, it is 100 degrees C or less, More preferably, it is 80 degrees C or less. If it is less than 0 ° C, the effect of improving the initial grip performance can be obtained, but there is a possibility that stable grip performance and wear resistance during running and the latter period may not be obtained well. Although the effect of improving the grip performance under extreme heat environment can be obtained, the initial grip performance and wear resistance may not be obtained well.
In the present invention, the glass transition point of the acrylic resin is a value measured by performing differential scanning calorimetry (DSC) according to JIS K 7121 under the condition of a heating rate of 10 ° C./min.

The Tg of the alkylphenol-based resin, the coumarone indene resin, and the terpene phenol resin is 60 ° C. or higher, preferably 65 ° C. or higher, more preferably 80 ° C. or higher. The Tg is preferably 110 ° C. or lower, more preferably 105 ° C. or lower, and still more preferably 100 ° C. or lower. If the temperature is less than 60 ° C, the effect of improving the initial grip performance can be obtained, but there is a possibility that stable grip performance and wear resistance during driving and the latter period may not be obtained well. Although the effect of improving the grip performance under extreme heat environment can be obtained, the initial grip performance and wear resistance may not be obtained well.
In the present invention, the glass transition point of the alkylphenol-based resin, coumarone indene resin, and terpene phenol resin is measured by performing differential scanning calorimetry (DSC) under the temperature increase rate of 10 ° C./min according to JIS K7121. Is the value to be

The hydroxyl value (OH value) of the acrylic resin, the alkylphenol resin, the coumarone indene resin and the terpene phenol resin is preferably 15 mgKOH / g or more, more preferably 30 mgKOH / g or more. The OH value is preferably 250 mgKOH / g or less, more preferably 200 mgKOH / g or less. If it is less than 15 mgKOH / g, the initial grip and the grip performance in the running / late stage may not be obtained at a high level. If it exceeds 250 mgKOH / g, the compatibility with the rubber component is deteriorated and sufficient destruction occurs. Characteristics may not be obtained and wear resistance may be significantly deteriorated.
In the present invention, the OH value of acrylic resin, alkylphenol resin, coumarone indene resin, and terpene phenol resin means the hydroxylation required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of resin. The amount of potassium is expressed in milligrams, and is a value measured by potentiometric titration (JIS K 0070: 1992). In addition, since acetylation by an acetic acid does not generate | occur | produce in a carboxyl group-containing acrylic resin, since OH value cannot be measured, the acid value mentioned later can be used instead of OH value.

In particular, the OH value of the acrylic resin is preferably 50 mgKOH / g or more, more preferably 60 mgKOH / g or more. The OH value is preferably 350 mgKOH / g or less, more preferably 300 mgKOH / g or less. The effect of this invention can fully be exhibited as it is in the said range.

In particular, the OH value of the alkylphenol-based resin is preferably 100 mgKOH / g or more, more preferably 150 mgKOH / g or more. The effect of this invention can fully be exhibited as it is in the said range.

In particular, the OH value of the coumarone indene resin is preferably 150 mgKOH / g or less, more preferably 100 mgKOH / g or less. The effect of this invention can fully be exhibited as it is in the said range.

In particular, the OH value of the terpene phenol resin is preferably 40 mgKOH / g or more. The OH value is preferably 150 mgKOH / g or less, more preferably 100 mgKOH / g or less. The effect of this invention can fully be exhibited as it is in the said range.

The acid value of the carboxyl group-containing acrylic resin is preferably 15 mgKOH / g or more, more preferably 30 mgKOH / g or more, and still more preferably 50 mgKOH / g or more. The acid value is preferably 350 mgKOH / g or less, more preferably 300 mgKOH / g or less, and still more preferably 280 mgKOH / g or less. If it is less than 15 mgKOH / g, the initial grip and the grip performance in the running / late stage may not be obtained at a high level. If it exceeds 350 mgKOH / g, the compatibility with the rubber component is deteriorated and sufficient destruction occurs. Characteristics may not be obtained and wear resistance may be significantly deteriorated.
In the present invention, the acid value of the carboxyl group-containing acrylic resin is the amount of potassium hydroxide required to neutralize the acid contained in 1 g of the resin, expressed in milligrams, and potentiometric titration method. (JIS K 0070: 1992).

The weight average molecular weight (Mw) of the acrylic resin is preferably 2,000 or more, more preferably 3,000 or more. The Mw is preferably 20,000 or less, more preferably 19,000 or less, and still more preferably 18,000 or less. If it is less than 2,000, an improvement in the initial grip performance can be obtained, but there is a possibility that a stable grip performance in the running / late period may not be obtained well. If it exceeds 20,000, dispersibility in rubber and There is a risk that the blooming property on the tire surface during and after the running will deteriorate and the improvement in grip performance will be reduced.

The Mw of the alkylphenol-based resin, the coumarone indene resin, and the terpene phenol resin is preferably 500 or more, more preferably 530 or more. The Mw is preferably 2,000 or less, more preferably 1,500 or less. If it is less than 500, the initial grip performance can be improved, but there is a possibility that the stable grip performance in the running / late period may not be obtained well. If it exceeds 2,000, the dispersibility in the rubber and the running・ The bloom property to the tire surface in the latter period may deteriorate and the improvement in grip performance may be reduced.
In the present invention, Mw of acrylic resin, alkylphenol resin, coumarone indene resin and terpene phenol resin is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

The acrylic resin, the alkylphenol resin, the coumarone indene resin, and the terpene phenol resin are, for example, commercially available acrylic resin, alkylphenol resin, coumarone indene resin, terpene phenol resin, etc. It is prepared by imparting characteristics such as N ₂ SA. Examples of the pulverization treatment include conventionally known methods such as wet pulverization and dry pulverization (jet mill, current jet mill, counter jet mill, contraplex, etc.).

Specifically, as the acrylic resin, ARUFON series manufactured by Toagosei Co., Ltd. (UH-2170, UC-3000, UC-3900, UC-3920, UF-5080, UF-5022, UG-4035, UG -4040, UG-4070) and the like obtained by pulverization treatment, as the alkylphenol-based resin, as obtained by pulverization treatment on the commercial product such as BASF Koresin, and as the coumarone indene resin Commercially available products such as Knitlon Coumarone V-120 and V-120S manufactured by Nikko Chemical Co., Ltd. YS Polystar series (T160, T145, S145) manufactured by Yashara Chemical Co., Ltd. as the terpene phenol resin. ) And the like obtained by pulverizing a commercially available product.

The content of the acrylic resin is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 50 mass parts or less, More preferably, it is 40 mass parts or less, More preferably, it is 30 mass parts or less. If the amount is less than 1 part by mass, sufficient adhesive effect may not be obtained, and there is a risk that both the initial grip performance and the improvement in grip performance during running and in the latter stage may not be obtained. May not be obtained, and the wear resistance may be significantly deteriorated.

The content of the alkylphenol-based resin is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 4 parts by mass or more, and particularly preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. . Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 60 mass parts or less, More preferably, it is 40 mass parts or less. If the amount is less than 1 part by mass, sufficient adhesive effect cannot be obtained, and there is a possibility that both the initial grip performance and the improvement in grip performance during running and in the latter stage may not be obtained. May not be obtained, and the wear resistance may be significantly deteriorated.

The content of the coumarone indene resin is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 4 parts by mass or more, and particularly preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. is there. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 60 mass parts or less, More preferably, it is 40 mass parts or less. If the amount is less than 1 part by mass, sufficient adhesive effect cannot be obtained, and there is a possibility that both the initial grip performance and the improvement in grip performance during running and in the latter stage may not be obtained. May not be obtained, and the wear resistance may be significantly deteriorated.

The content of the terpene phenol resin is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 4 parts by mass or more, and particularly preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. . Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 60 mass parts or less, More preferably, it is 40 mass parts or less. If the amount is less than 1 part by mass, sufficient adhesive effect cannot be obtained, and there is a possibility that both the initial grip performance and the improvement in grip performance during running and in the latter stage may not be obtained. May not be obtained, and the wear resistance may be significantly deteriorated.

The total content of the acrylic resin, the alkylphenol resin, the coumarone indene resin and the terpene phenol resin is 1 part by mass or more, preferably 2 parts by mass or more, more preferably 100 parts by mass of the rubber component. 4 parts by mass or more, more preferably 8 parts by mass or more. Moreover, this total content is 100 mass parts or less, Preferably it is 90 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 70 mass parts or less. If the amount is less than 1 part by mass, sufficient adhesive effect cannot be obtained, and neither the initial grip performance nor the improvement of the grip performance during running / late stage can be obtained, and if it exceeds 100 parts by mass, sufficient fracture characteristics can be obtained. Therefore, the wear resistance is remarkably deteriorated.

In the present invention, in addition to the acrylic resin, the alkylphenol resin, the coumarone indene resin, and the terpene phenol resin, other acrylic resins, alkylphenol resins, coumarone indenes are used as long as the effects of the present invention are not impaired. You may mix | blend resin, such as resin and terpene phenol resin. In the present invention, the acrylic resin is used in combination with any alkylphenol resin such as the alkylphenol resin, or the acrylic resin is used in combination with any coumarone indene resin such as the coumarone indene resin. It is particularly preferable to use the acrylic resin in combination with any coumarone indene resin such as the coumarone indene resin.

In the present invention, it is preferable that a softener is further blended from the viewpoints of initial grip performance, stable grip performance during running and later stages, and the like. Although it does not specifically limit as a softening agent, Oil, a liquid diene polymer, etc. are mentioned.

Examples of the oil include process oils such as paraffinic, aroma-based and naphthenic process oils.

When oil is blended, the oil content is preferably 20 parts by mass or more, more preferably 25 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 85 mass parts or less, More preferably, it is 75 mass parts or less. If the amount is less than 20 parts by mass, the effect of the addition may not be obtained. If the amount exceeds 85 parts by mass, the wear resistance tends to deteriorate. In the present specification, the oil content includes the amount of oil contained in the oil-extended rubber.

The liquid diene polymer is a diene polymer in a liquid state at normal temperature (25 ° C.).
The liquid diene polymer preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 1.0 × 10 ^{3 to} 2.0 × 10 ⁵ measured by gel permeation chromatography (GPC), 3.0 It is more preferable that it is * 10 < ³ > -1.5 * 10 < ⁴ >. If it is less than 1.0 × 10 ³ , the grip performance is not improved and sufficient durability may not be ensured. On the other hand, if it exceeds 2.0 × 10 ⁵ , the viscosity of the polymerization solution becomes too high, and the productivity may be deteriorated or the fracture characteristics may be deteriorated. In the present invention, Mw of the liquid diene polymer is a polystyrene conversion value measured by gel permeation chromatography (GPC).

Examples of the liquid diene polymer include a liquid styrene butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), a liquid styrene isoprene copolymer (liquid SIR), and the like. It is done. Among these, liquid SBR is preferable because it provides a good balance between wear resistance and stable grip performance during and after traveling.

When the liquid diene polymer is blended, the content of the liquid diene polymer is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 120 mass parts or less, More preferably, it is 80 mass parts or less. If it is less than 10 parts by mass, sufficient grip performance tends not to be obtained, and if it exceeds 120 parts by mass, the wear resistance tends to deteriorate.

The total content of the various resins such as the acrylic resin, the alkylphenol resin, the coumarone indene resin, the terpene phenol resin, and other acrylic resins, the oil, and the liquid diene polymer is 100 mass of a rubber component. Preferably it is 50-250 mass parts with respect to a part, More preferably, it is 100-200 mass part, More preferably, it is 120-180 mass part. The effect of this invention is acquired more suitably as the said content is in the said range.

The rubber composition for a tread in the present invention preferably contains carbon black from the viewpoint of excellent wear resistance.

_N 2 SA of the carbon black is preferably 100 m ² / g or more, more preferably at least 105m ² / g, more 110m ² / g is more preferable. The N ₂ SA is preferably 600 m ² / g or less, more preferably 250 m ² / g or less, and still more preferably 200 m ² / g or less. If it is less than 100 m ² / g, the grip performance tends to decrease, and if it exceeds 600 m ² / g, good dispersion is difficult to obtain, and the wear resistance tends to decrease. In addition, N ₂ SA of carbon black is obtained in accordance with ASTM D 6556.

The specific surface area of cetyltrimethylammonium bromide (CTAB) of carbon black is preferably 100 m ² / g or more, and more preferably 120 m ² / g or more. Further, the _N 2 SA is preferably from 300 meters ² / g or less, more preferably 250m ² / g. If it is less than 100 m ² / g, the grip performance tends to decrease, and if it exceeds 300 m ² / g, good dispersion is difficult to obtain, and the wear resistance tends to decrease. In addition, the CTAB specific surface area of carbon black is measured according to ASTM D 3765.

The content of carbon black is preferably 50 parts by mass or more, more preferably 80 parts by mass or more, and still more preferably 100 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 200 mass parts or less, More preferably, it is 150 mass parts or less. If the amount is less than 50 parts by mass, sufficient wear resistance and grip performance may not be obtained. If the amount exceeds 200 parts by mass, fracture characteristics, wear resistance and grip performance may be deteriorated.

The rubber composition for a tread in the present invention preferably contains at least one inorganic filler selected from the group consisting of a compound represented by the following formula, magnesium sulfate, and silicon carbide.
mM · xSiO _y · zH ₂ O
Wherein M is at least one metal selected from the group consisting of Al, Mg, Ti, Ca and Zr, an oxide or hydroxide of the metal, m is an integer of 1 to 5, and x is (An integer of 0 to 10, y is an integer of 2 to 5, and z is an integer of 0 to 10.)

Examples of the compound represented by the above formula include alumina, alumina hydrate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, talc, titanium white, titanium black, calcium oxide, calcium hydroxide, magnesium aluminum oxide, clay, pyro Examples thereof include phyllite, bentonite, aluminum silicate, magnesium silicate, calcium silicate, aluminum calcium silicate, magnesium silicate, zirconium, and zirconium oxide. An inorganic compound may be used independently and may be used in combination of 2 or more type.

Among the above inorganic fillers, it has a Mohs hardness of 3 or more, water resistance, and oil resistance, and when processed into a particle size of a micron unit, a scratching effect is produced or a bloom of an adhesive component that expresses grip performance is promoted. This improves the grip performance. In addition, from the point that good wear resistance can be obtained, a metal having M of Al or Zr, an oxide or hydroxide of the metal is preferable, and from the point that the amount of resources is abundant and inexpensive, aluminum hydroxide, oxidation Zirconium is more preferred. Further, aluminum hydroxide is particularly preferable from the viewpoint of obtaining good kneading productivity and extrusion processability.

The N ₂ SA of the inorganic filler is preferably 5 to 120 m ² / g. Outside the above range, wear resistance and grip performance may be deteriorated. The lower limit of the N ₂ SA is more preferably 10 m ² / g. Further, the upper limit of the N ₂ SA is more preferably 115 m ² / g, still more preferably 110 m ² / g.
Incidentally, _N 2 SA of the inorganic filler is a value measured by the BET method in accordance with ASTM D3037-81.

The average particle diameter of the inorganic filler is preferably 1.5 μm or less, more preferably 0.69 μm or less, and still more preferably 0.6 μm or less. The average particle diameter is preferably 0.2 μm or more, more preferably 0.25 μm or more, and further preferably 0.4 μm or more. If it exceeds 1.5 μm, wear resistance and grip performance may be reduced. If it is less than 0.2 μm, secondary agglomerates in the rubber are likely to be formed, and wear resistance and grip performance are deteriorated. There is a risk. In addition, the average particle diameter of an inorganic filler is a number average particle diameter, and is measured with a transmission electron microscope.

The Mohs hardness of the inorganic filler is preferably 7 or less, comparable to silica, from the viewpoint of ensuring the wear resistance and grip performance of the tire and suppressing metal wear of a Banbury mixer or an extruder. More preferably. Mohs hardness is one of the mechanical properties of materials and is a measurement method that has been widely used in minerals for a long time. Scrub a substance you want to measure hardness (such as aluminum hydroxide) with a standard substance and check for scratches. Measure Mohs hardness.

In particular, it is preferable to use an inorganic filler having a Mohs hardness of less than 7 and a Mohs hardness of the inorganic filler dehydration reaction product of 8 or more. For example, aluminum hydroxide has a Mohs hardness of about 3 and prevents abrasion (wear) of the banbury and rolls, and the surface layer undergoes a dehydration reaction (transition) due to vibration, heat generation and partial kneading during running and late, Since it is converted to alumina with a Mohs hardness of about 9 and has a hardness higher than that of road stones, excellent wear resistance and grip performance can be obtained. Here, it is not necessary to convert the entire inside of the aluminum hydroxide, and a road surface scratching function can be expressed by partial conversion. Aluminum hydroxide and alumina are stable against water, base and acid, and do not inhibit vulcanization or promote oxidative degradation. The Mohs hardness after the transfer of the inorganic filler is more preferably 7 or more, and the upper limit is not particularly limited. Diamonds have a maximum value of 10.

The inorganic filler preferably has a thermal decomposition start temperature (DSC endothermic start temperature) of 160 to 500 ° C, more preferably 170 to 400 ° C. If the temperature is lower than 160 ° C., thermal decomposition or reaggregation proceeds excessively during kneading, and metal wear such as the rotor blades of the kneader or the wall of the container may be excessive. In addition, the thermal decomposition start temperature of an inorganic filler is calculated | required by implementing differential scanning calorimetry (DSC). The thermal decomposition also includes a dehydration reaction.

The inorganic filler can be used a commercially available product having the N ₂ SA, also like subjected to a treatment such as grinding an inorganic filler treated product was adjusted to a particle having the above characteristics can be used. When the pulverization treatment is performed, conventionally known methods such as wet pulverization and dry pulverization (jet mill, current jet mill, counter jet mill, contraplex, etc.) can be applied.
Further, if necessary, it is fractionated by a membrane filter method frequently used in medicine and bio-related, and a product having a predetermined N ₂ SA can be prepared and used as a rubber compounding agent.

The content of the inorganic filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 1 part by mass, sufficient grip performance may not be obtained. Moreover, this content becomes like this. Preferably it is 70 mass parts or less, More preferably, it is 65 mass parts or less, More preferably, it is 60 mass parts or less. When it exceeds 70 mass parts, there exists a possibility that abrasion resistance may deteriorate.

In the present invention, as the reinforcing filler, those conventionally used in rubber compositions for tires such as silica and calcium carbonate can also be used.

In addition to the above components, the tread rubber composition in the present invention includes compounding agents generally used in the tire industry, such as wax, zinc oxide, stearic acid, mold release agent, anti-aging agent, sulfur and the like. Materials such as vulcanizing agents and vulcanization accelerators may be appropriately blended.

The zinc oxide used in the present invention is not particularly limited, and examples thereof include those used in the rubber field such as tires. Here, fine zinc oxide can be suitably used among zinc oxides. Specifically, it is preferable to use zinc oxide having an average primary particle diameter of 200 nm or less, and more preferably 100 nm or less. Although the minimum of this average primary particle diameter is not specifically limited, Preferably it is 20 nm or more, More preferably, it is 30 nm or more. In addition, the average primary particle diameter of zinc oxide represents the average particle diameter (average primary particle diameter) converted from the specific surface area measured by the BET method by nitrogen adsorption. The specific surface area measured by the BET method by nitrogen adsorption _(N 2 SA) is preferably 10 to 50 m ² / g.

When blending zinc oxide, the content of zinc oxide is preferably 0.5 to 10 parts by mass or less, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component. The effect of this invention is acquired more suitably as content of zinc oxide exists in the said range.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, guanidine, and dithiocarbamate vulcanization accelerators. Among them, in the present invention, thiazole, thiuram, and dithiocarbamate are used. A system vulcanization accelerator can be preferably used.

Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and the like. Among them, di-2-benzothia Zolyl disulfide is preferred. Examples of thiuram-based vulcanization accelerators include tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N), and among them, TOT-N preferable. Examples of the dithiocarbamate vulcanization accelerator include zinc dibenzyldithiocarbamate (ZTC) and zinc ethylphenyldithiocarbamate (PX).

When the vulcanization accelerator is blended, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 15 parts by mass with respect to 100 parts by mass of the rubber component. Part or less, more preferably 10 parts by weight or less. If it is less than 1 part by mass, a sufficient vulcanization speed cannot be obtained, and there is a tendency that good grip performance and wear resistance cannot be obtained. If it exceeds 15 parts by mass, blooming occurs and grip performance and wear resistance are poor. May decrease.

The rubber composition for a tread in the present invention can be produced by a conventionally known method.
First, after compounding (adding) components other than sulfur and a vulcanization accelerator into a rubber kneading apparatus such as a Banbury mixer or an open roll and kneading (base kneading step), sulfur and vulcanization are further added to the obtained kneaded product. It can be produced by a method of blending (adding) a sulfur accelerator, kneading and then vulcanizing.

The base kneading step is not particularly limited as long as the rubber component or the like is kneaded, in addition to the method of performing the base kneading step in one step, the rubber component, the acrylic resin, the alkylphenol resin, the above A divided two-step base kneading step may be used in which the coumarone indene resin or the terpene phenol resin is kneaded in advance and the kneaded product and other components excluding sulfur and the vulcanization accelerator are kneaded.

The rubber composition is suitable for a tread for a pneumatic tire, particularly for a cap tread for a high-performance vehicle.

The pneumatic tire of the present invention is produced by a usual 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 of the present invention can be used for tires for passenger cars, trucks and buses, sports cars, two-wheeled motorbikes, competition vehicles, etc., 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 limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
SBR: Toughden 4850 manufactured by Asahi Kasei Corporation (styrene content: 40% by mass, containing 50 parts by mass of oil with respect to 100 parts by mass of rubber solid content)
Carbon black: HP180 manufactured by Orion Engineered Carbons (N ₂ SA: 175 m ² / g, CTAB specific surface area: 181 m ² / g)
Liquid diene polymer: L-SBR-820 (liquid SBR, Mw: 10,000) manufactured by Kuraray Co., Ltd.
Oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Inorganic filler 1 (aluminum hydroxide 1): dry pulverized product of ATH # B manufactured by Sumitomo Chemical Co., Ltd. (average particle size: 0.5 μm, N ₂ SA: 75 m ² / g, Mohs hardness: 3, thermal decomposition product (Morse hardness of (alumina): 9, thermal decomposition start temperature: 200 ° C.)
Inorganic filler 2 (aluminum hydroxide 2): ATH # B manufactured by Sumitomo Chemical Co., Ltd. (average particle size: 0.6 μm, N ₂ SA: 15 m ² / g, Mohs hardness: 3, thermal decomposition product (alumina)) Mohs hardness: 9, thermal decomposition start temperature: 200 ° C)
Inorganic filler 3 (aluminum hydroxide 3): Heidilite H-43 (average particle size: 0.75 μm, N ₂ SA: 6.7 m ² / g, Showa Denko Co., Ltd., Mohs hardness: 3, thermal decomposition product (Morse hardness of (alumina): 9, thermal decomposition start temperature: 200 ° C.)
Acrylic resin 1-1: ARUFON UC-3900 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 60 ° C., acid value: 108 mgKOH / g, (Mw: 4,600, N ₂ SA: 0 m ² / g)
Acrylic resin 1-2: dry pulverized product of ARUFON UC-3900 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 60 ° C., acid value: (108 mg KOH / g, Mw: 4,600, N ₂ SA: 0.2 m ² / g)
Acrylic resin 1-3: dry pulverized product of ARUFON UC-3900 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 60 ° C., acid value: 108 mg KOH / g, Mw: 4,600, N ₂ SA: 1.5 m ² / g)
Acrylic resin 1-4: dry pulverized product of ARUFON UC-3900 (solvent-free styrene acrylic resin (containing carboxyl group), manufactured by Toagosei Co., Ltd., purity: 98% by mass or more, Tg: 60 ° C., acid value: (108 mg KOH / g, Mw: 4,600, N ₂ SA: 4.0 m ² / g)
Acrylic resin 2-1: ARUFON UH-2170 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing hydroxyl group), purity of 98% by mass or more, Tg: 60 ° C., OH value: 88 mgKOH / g, Mw: 14,000, N ₂ SA: 0 m ² / g)
Acrylic resin 2-2: dry pulverized product of 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., OH value: 88 mgKOH / g, Mw: 14,000, N ₂ SA: 0.2 m ² / g)
Acrylic resin 2-3: dry pulverized product of ARUFON UH-2170 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing hydroxyl group), purity of 98% by mass or more, Tg: 60 ° C., OH value: 88 mgKOH / g, Mw: 14,000, N ₂ SA: 1.5 m ² / g)
Acrylic resin 2-4: ARUFON UH-2170 dry pulverized product manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing hydroxyl group), purity of 98% by mass or more, Tg: 60 ° C., OH value: 88 mgKOH / g, Mw: 14,000, N ₂ SA: 5.0 m ² / g)
Acrylic resin 3-1: ARUFON UC-3920 (solvent-free styrene acrylic resin (carboxyl group-containing), manufactured by Toagosei Co., Ltd., purity: 98 mass% or more, Tg: 102 ° C., acid value: 240 mgKOH / g, (Mw: 15,500, N ₂ SA: 0 m ² / g)
Acrylic resin 3-2: dry pulverized product of ARUFON UC-3920 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 102 ° C., acid value: 240 mg KOH / g, Mw: 15,500, N ₂ SA: 0.2 m ² / g)
Acrylic resin 3-3: dry pulverized product of ARUFON UC-3920 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 102 ° C., acid value: 240 mg KOH / g, Mw: 15,500, N ₂ SA: 1.8 m ² / g)
Acrylic resin 3-4: dry pulverized product of ARUFON UC-3920 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 102 ° C., acid value: 240 mg KOH / g, Mw: 15,500, N ₂ SA: 11.0 m ² / g)
Acrylic resin 4: 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, Mw : 2,000)
Acrylic resin 5: 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, Mw: 10,000, N ₂ SA: 4.0 m ² / g)
Acrylic resin 6: dry pulverized product of ARUFON UC-3080 manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic resin (containing carboxyl group), purity: 98% by mass or more, Tg: 133 ° C., acid value: 230 mgKOH / g, Mw: 14,000, N ₂ SA: 12.3 m ² / g)
Alkylphenol resin 1-1: Koresin manufactured by BASF (condensation resin of pt-butylphenol and acetylene, Tg: 98 ° C., OH value: 198 mg KOH / g, N ₂ SA: 0 m ² / g)
Alkylphenol resin 1-2: Koresin manufactured by BASF (condensation resin of pt-butylphenol and acetylene, Tg: 98 ° C., OH value: 198 mgKOH / g, N ₂ SA: 4.0 m ² / g)
Coumarone Indene Resin 1-1: Coumarone V-120 (Coumarone Indene Resin, Tg: 65 ° C., OH Value: 30 mg KOH / g, Mw: 960, N ₂ SA: 0 m ² / g, manufactured by Nikkiso Chemical Co. )
Coumarone indene resin 1-2: Dry pulverized product of Coumarone V-120 manufactured by Nikkaku Chemical Co., Ltd. (coumarone indene resin, Tg: 65 ° C., OH value: 30 mg KOH / g, Mw: 960, N ₂ SA: 4.0m ² / g)
Aromatic terpene resin 1-1: YS resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (aromatic modified terpene resin, Tg: 65 ° C., OH value: 0 mg KOH / g, N ₂ SA: 0 m ² / g)
Aromatic terpene resin 1-2: dry pulverized product of YS resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (aromatic modified terpene resin, Tg: 65 ° C., OH value: 0 mg KOH / g, N ₂ SA: 4.0 m ² / g )
Terpene phenol resin 1-1: Sylvares TP115 manufactured by Arizona Chemical Co., Ltd. (terpene phenol resin, Tg: 57 ° C., OH value: 50 mg KOH / g, Mw: 600, N ₂ SA: 0 m ² / g)
Terpene phenol resin 1-2: dry pulverized product of Sylvares TP115 manufactured by Arizona Chemical Co., Ltd. (terpene phenol resin, Tg: 57 ° C., OH value: 50 mg KOH / g, Mw: 600, N ₂ SA: 4.0 m ² / g)
Terpene phenol resin 2-1: YS Polystar T160 manufactured by Yashara Chemical Co., Ltd. (terpene phenol resin, Tg: 100 ° C., OH value: 56 mg KOH / g, N ₂ SA: 0 m ² / g)
Terpene phenol resin 2-2: dry pulverized product of YS polystar T160 manufactured by Yasuhara Chemical Co., Ltd. (terpene phenol resin, Tg: 100 ° C., OH value: 56 mg KOH / g, N ₂ SA: 3.8 m ² / g)
Zinc oxide: Zincock Super F-2 manufactured by Hakusuitec Co., Ltd. (average primary particle size: 65 nm, N ₂ SA: 20 m ² / g)
Anti-aging agent 1: Antigen 6C (N-phenyl-N ′-(1,3-dimethyl) -p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Anti-aging agent 2: Nocrack 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Sulfur: HK-200-5 (5% oil-containing powder sulfur) manufactured by Hosoi Chemical Co., Ltd.
Vulcanization accelerator 1: Noxeller DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Noxeller TOT-N (tetrakis (2-ethylhexyl) thiuram disulfide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

<Examples and Comparative Examples>
In accordance with the formulation shown in Table 1, compounding materials other than sulfur and a vulcanization accelerator were kneaded for 5 minutes at a discharge temperature of 150 ° C. using 4.0 L Banbury manufactured by Kobe Steel. Sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 4 minutes under the condition of a discharge temperature of 95 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was molded into a tread shape, bonded together with other tire members on a tire molding machine, vulcanized at 160 ° C. for 20 minutes, and a test tire (tire size: 215). / 45R17).
In Examples 20 and 21, the rubber component and the acrylic resin were previously kneaded, that is, the rubber component and the acrylic resin 1-4, and the rubber component and the acrylic resin 3-4 were discharged at 120 ° C., respectively. After pre-kneading for 4 minutes under the conditions, a test tire was obtained under the same conditions as in other formulation examples.

The following evaluation was performed about the test tire obtained by the said manufacture. The results are shown in Table 1.

(Initial grip performance)
The test tire was mounted on a 2000 cc domestic FR vehicle, and the vehicle traveled 10 laps on a dry asphalt road test course. At that time, the test driver evaluated the control stability during steering in the second lap, and the index was displayed with Comparative Example 1 as 100 (initial grip performance index). The larger the value, the higher the initial grip performance. The index value was judged to be good when it was 100 or more, and particularly good when it was 110 or more.

(Grip performance during and late driving)
The test tire was mounted on a 2000 cc domestic FR vehicle, and the vehicle traveled 10 laps on a dry asphalt road test course. At that time, the test driver compared and evaluated the stability of control during steering of the best lap and the final lap. The larger the value, the smaller the decrease in grip performance during and late driving on the dry road surface, indicating that stable grip performance during and during driving can be obtained better. The index value was judged to be good when it was 100 or more, and particularly good when it was 110 or more.

(Abrasion resistance)
The test tire was mounted on a domestic FR vehicle with a displacement of 2000 cc, 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 Comparative Example 1 being 100 (wear resistance index). It shows that abrasion resistance is so high that a numerical value is large. When the index value was 88 or more, it was judged to be good.

As shown in Table 1, in the examples in which specific resins of predetermined N ₂ SA and Tg were blended, the initial grip performance and the stable grip performance during the running / late period were secured while ensuring good wear resistance (especially the initial grip on the dry road surface). It was revealed that the performance and stable grip performance during and late driving can be improved at the same time.

Claims (7)

A rubber component and an acrylic resin having a nitrogen adsorption specific surface area of 0.5 m ² / g or more and a glass transition temperature of 0 to 110 ° C. and / or a nitrogen adsorption specific surface area of 0.5 m ² / g or more and a glass transition temperature of 60 ° C. or more. Containing at least one resin selected from the group consisting of alkylphenol resins, coumarone indene resins and terpene phenol resins,
A tread produced using a rubber composition in which the total content of the acrylic resin, the alkylphenol resin, the coumarone indene resin, and the terpene phenol resin is 1 to 100 parts by mass with respect to 100 parts by mass of the rubber component. Pneumatic tire having The pneumatic tire according to claim 1, wherein the acrylic resin is a solventless acrylic resin. The pneumatic tire according to claim 1 or 2, wherein the acrylic resin is a solventless styrene acrylic resin. The pneumatic tire according to any one of claims 1 to 3, wherein a hydroxyl value or an acid value of the acrylic resin, the alkylphenol resin, the coumarone indene resin, and the terpene phenol resin is 15 to 250 mgKOH / g. The acrylic resin, the alkylphenol resin, the coumarone-indene resin and pneumatic tire according to any one of claims 1 to 4 nitrogen adsorption specific surface area of the terpene phenol resin is 2m 2 ^{/ g} or more. 100 parts by mass of the rubber component comprising an inorganic filler consisting of at least one selected from the group consisting of a compound represented by the following formula, magnesium sulfate, and silicon carbide, and having a nitrogen adsorption specific surface area of 5 to 120 m ² / g The pneumatic tire according to any one of claims 1 to 5, which is contained in an amount of 1 to 70 parts by weight based on the weight.
mM · xSiO _y · zH ₂ O
Wherein M is at least one metal selected from the group consisting of Al, Mg, Ti, Ca and Zr, an oxide or hydroxide of the metal, m is an integer of 1 to 5, and x is (An integer of 0 to 10, y is an integer of 2 to 5, and z is an integer of 0 to 10.) The pneumatic tire according to any one of claims 1 to 6, wherein the inorganic filler is aluminum hydroxide.