JP2014009265A - Rubber composition for high performance wet tire tread, and high performance wet tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a rubber composition for a high performance wet tire tread that can improve heat sag resistance and abrasion resistance while maintaining or improving favorable wet grip performance; and a high performance wet tire using the same.SOLUTION: A rubber composition for a high performance wet tire tread includes: at least one chosen from a group consisting of a natural rubber and a diene-based synthetic rubber; carbon black; an amphoteric compound that has acidic and basic functional groups; and an inorganic compound represented by following formula (a) and having an average primary particle diameter of at most 10 μm. kMxSiOzHO (a). In the formula (a), Mis at least one metal chosen from a group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1-5, x is an integer of 0-10, y is an integer of 2-5, and z is an integer of 0-10.

Description

The present invention relates to a rubber composition for a high performance wet tire tread and a high performance wet tire produced using the rubber composition.

A high-performance wet tire tread rubber composition is required to have high wet grip performance, thermal sag performance, and abrasion resistance, and various devices have been made to ensure these performances. However, wet grip performance and wear resistance are contradictory performances, and it is difficult to achieve both.

For example, Patent Document 1 describes that wet grip performance can be improved by blending aluminum hydroxide, but there is a problem that wear resistance is lowered.

JP 2005-213353 A

The present invention solves the above-mentioned problems, and maintains or improves good wet grip performance while improving heat sag performance and wear resistance, and a high performance wet tire tread rubber composition using the same. The object is to provide a tire.

The present invention represents at least one selected from the group consisting of natural rubber and diene-based synthetic rubber, carbon black, an amphoteric compound having acidic and basic functional groups, and the following formula (E), average primary The present invention relates to a rubber composition for a high performance wet tire tread containing an inorganic compound having a particle size of 10 μm or less.
kM ₁・ xSiO _y・ zH ₂ O
(In the formula (A), M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, x Is an integer from 0 to 10, y is an integer from 2 to 5, and z is an integer from 0 to 10.)

（式（Ｉ）中、Ｒ^１は、炭素数２〜３０のアルキレン基、アルケニレン基又はアルキニレン基を表す。Ａは酸性官能基を表す。Ｒ^２及びＲ^３は、同一又は異なって、水素原子、炭素数１〜２０のアルキル基、アルケニル基若しくはアルキニル基、又は炭素数１〜２０のアルコキシシリル基を表す。式（Ｉ）で表される化合物は、該化合物の金属塩でもよい。） The amphoteric compound is preferably a compound represented by the following formula (I).

(In the formula (I), R ¹ represents an alkylene group having 2 to 30 carbon atoms, an alkenylene group or an alkynylene group. A represents an acidic functional group. R ² and R ³ are the same or different and represent a hydrogen atom. Represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an alkynyl group, or an alkoxysilyl group having 1 to 20 carbon atoms.The compound represented by the formula (I) may be a metal salt of the compound.)

（式（Ｉ−１）中、ｐは２〜８の整数を表す。式（Ｉ−２）中、ｑは２〜８の整数を表す。Ｍ^ｒ＋は金属イオンを表し、ｒはその価数を表す。） The amphoteric compound is preferably a compound represented by the following formula (I-1) and / or the following formula (I-2).

(In formula (I-1), p represents an integer of 2 to 8. In formula (I-2), q represents an integer of 2 to 8. Mr ⁺ represents a metal ion, and r represents a valence thereof. Represents.)

The metal ion represented by ^{Mr +} in the above formula (I-2) is preferably a lithium ion, a sodium ion, a potassium ion, a cesium ion, a cobalt ion, a copper ion, or a zinc ion.

The content of styrene butadiene rubber in 100% by mass of the rubber component is preferably 60 to 100% by mass.

It is preferable that the carbon black content is 10 to 50 parts by mass, the silica content is 30 to 100 parts by mass, and the inorganic compound content is 5 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

The inorganic compound is preferably an inorganic compound represented by the following formula (B).
Al (OH) _a O _b (Otsu)
(In the formula (B), 0 ≦ a ≦ 3, b = (3-a) / 2.)

The inorganic compound is preferably aluminum hydroxide.

The amphoteric compound content is preferably 0.01 to 0.8 parts by mass with respect to 100 parts by mass in total of carbon black, silica and inorganic compounds.

The present invention relates to a high performance wet tire produced using the rubber composition for a high performance wet tire tread.

According to the present invention, at least one selected from the group consisting of natural rubber and diene-based synthetic rubber, carbon black, an amphoteric compound having acidic and basic functional groups, and a specific inorganic compound are included. Since it is a rubber composition for performance wet tire treads, it is possible to improve thermal sag performance and wear resistance while maintaining or improving good wet grip performance.

The rubber composition for a high-performance wet tire tread of the present invention is an amphoteric compound having at least one selected from the group consisting of natural rubber (NR) and diene-based synthetic rubber, carbon black, and acidic and basic functional groups And a specific inorganic compound.

When carbon black and an amphoteric compound having both an acidic functional group and a basic functional group are blended with natural rubber or a diene-based synthetic rubber, the acidic functional group of the amphoteric compound reacts with the rubber to produce a basic functional group. Since the group reacts with the carbon black surface, the dispersibility of the carbon black is improved, and heat generation can be appropriately suppressed by restraining the carbon black. Similarly, the basic functional group possessed by the amphoteric compound also reacts with the surface of a specific inorganic compound (for example, a hydroxyl group possessed by aluminum hydroxide), thereby improving the dispersibility of the specific inorganic compound and improving the dispersibility of the specific inorganic compound. Heat generation can be moderately suppressed by restraint. Therefore, in the present invention, carbon black, a specific inorganic compound compounded by blending carbon black, an amphoteric compound having acidic and basic functional groups, and a specific inorganic compound with natural rubber or diene synthetic rubber. While maintaining or improving the good wet grip performance due to, heat sag performance and wear resistance can be improved. In addition, by using an amphoteric compound and a specific inorganic compound in combination, the thermal sag performance could be improved synergistically. In addition, when the amphoteric compound and the specific inorganic compound were each blended alone, the wear resistance was lowered, but by using both, the wear resistance that could not be improved alone could be improved. .

In the present invention, the rubber component is NR, diene synthetic rubber (isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene. Rubber (NBR), ethylene propylene diene rubber (EPDM), butyl rubber (IIR), halogenated butyl rubber (X-IIR), etc.) are used. A rubber component may be used independently and may use 2 or more types together. Among these, NR, BR, and SBR are preferable, and SBR is more preferable because wet grip performance and wear resistance can be obtained in a well-balanced manner.

The SBR is not particularly limited, and for example, those commonly used in the tire industry such as emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR) can be used. Among these, E-SBR is preferable because it is excellent in workability, wet grip performance, wear resistance, and thermal sag performance.

The styrene content of SBR is preferably 25% by mass or more, more preferably 30% by mass or more. If the styrene content is less than 25% by mass, sufficient wet grip performance may not be obtained. The styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less. When the styrene content exceeds 60% by mass, not only the wear resistance is lowered, but also the temperature dependency is increased, and the performance change with respect to the temperature change is increased. For example, the thermal sag performance tends to be lowered.
In the present invention, the styrene content of SBR is calculated by ¹ H-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, and further preferably 60% by mass or more. If it is less than 10% by mass, sufficient wet grip performance and thermal sag performance tend not to be obtained. Further, the upper limit of the SBR content is not particularly limited, and may be 100% by mass.

In the present invention, carbon black is used.
The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 m ² / g or more, and more preferably 120 m ² / g or more. If it is less than 70 m ² / g, sufficient reinforcing properties cannot be obtained, and sufficient wear resistance and wet grip performance may not be obtained. The _N 2 SA is preferably 250 meters ² / g or less, more preferably 160 m ² / g. When it exceeds 250 m ² / g, the heat generation becomes large and the thermal sag performance tends to decrease.
Incidentally, _N 2 SA of carbon black, JIS K 6217-2: determined by 2001.

Carbon black has a dibutyl phthalate oil absorption (DBP) of preferably 50 ml / 100 g or more, and more preferably 100 ml / 100 g or more. If it is less than 50 ml / 100 g, sufficient reinforcing properties cannot be obtained, and sufficient abrasion resistance and wet grip performance may not be obtained. The DBP of carbon black is preferably 200 ml / 100 g or less, and more preferably 135 ml / 100 g or less. When it exceeds 200 ml / 100 g, the heat generation becomes large, and the thermal sag performance tends to decrease.
The DBP of carbon black is measured according to JIS K 6217-4: 2001.

The content of carbon black 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. If it is less than 10 parts by mass, sufficient wet grip performance and wear resistance may not be obtained. The content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. If it exceeds 50 parts by mass, the improvement in workability during unvulcanization is small, and the contribution to wet grip performance is also small. Further, the heat generation becomes large, and the heat sag performance tends to decrease.

In the present invention, an inorganic compound represented by the following formula (former) and having an average primary particle size of 10 μm or less is used.
kM ₁・ xSiO _y・ zH ₂ O
In (Formula (Jia), _{M 1} is at least one metal, oxide or hydroxide of the metal selected from the group consisting of Al, Mg, Ti and Ca, k is an integer of from 1 to 5 (preferably 1), x is an integer of 0 to 10 (preferably 0), y is an integer of 2 to 5, and z is an integer of 0 to 10 (preferably 0).

Examples of inorganic compounds represented by the above formula (A) include alumina, alumina hydrate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, talc, titanium white, titanium black, calcium oxide, calcium hydroxide, and aluminum magnesium oxide. Clay, pyrophyllite, bentonite, aluminum silicate, magnesium silicate, calcium silicate, aluminum calcium silicate, magnesium silicate and the like. These inorganic compounds may be used alone or in combination of two or more. Of these, M ₁ is a hydroxide of at least one metal selected from the group consisting of Al, Mg, Ti and Ca in the formula (A) because the effect of the present invention can be obtained more suitably. It is preferable that M ₁ is a hydroxide of Al. In addition, inorganic compounds represented by the following formula (B) can also be suitably used.
Al (OH) _a O _b (Otsu)
(In the formula (B), 0 ≦ a ≦ 3, b = (3-a) / 2.)

As an inorganic compound represented by the above formula (B), alumina Al ₂ O ₃ (a = 0), aluminum hydroxide Al (OH) ₃ (a = 3), alumina hydrate (0 <a <3) And any mixtures of such oxides or hydroxides. These may be used alone or in combination of two or more. Among these, aluminum hydroxide is particularly preferably used because the wet grip performance can be further improved.

The average primary particle diameter of the inorganic compound is preferably 0.5 μm or more, more preferably 0.8 μm or more. When the thickness is less than 0.5 μm, it is difficult to disperse the inorganic compound, and wear resistance tends to deteriorate. The average primary particle size is preferably 10 μm or less, more preferably 5 μm or less. When the thickness exceeds 10 μm, the inorganic compound becomes a fracture nucleus and wear resistance tends to deteriorate.
In addition, in this invention, the average primary particle diameter of the said inorganic compound is a number average particle diameter, and is measured with a transmission electron microscope.

The content of the inorganic compound (preferably aluminum hydroxide) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 mass parts, there exists a possibility that the improvement effect of wet grip performance may be small. The content of the inorganic compound is preferably 30 parts by mass or less, more preferably 25 parts by mass or less. If it exceeds 30 parts by mass, poor dispersion may occur and the wear resistance may deteriorate.

The rubber composition of the present invention preferably contains silica. When silica is blended, the hydroxyl group on the silica surface reacts with the basic functional group of the amphoteric compound, so that the dispersibility of the silica is improved and the heat generation can be moderately suppressed by the restraint of the silica. Therefore, the effect of the present invention can be more suitably obtained by blending silica. Examples of the silica include dry method silica (anhydrous silica), wet method silica (hydrous silica), and the like. Of these, wet-process silica is preferred because it has many silanol groups.

The cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of silica is preferably 100 to 300 m ² / g because good wet grip performance, wear resistance and durability can be obtained. Moreover, it is preferable that the dibutyl phthalate oil absorption (DBP) of a silica is 150-300 mL / 100g for the same reason.
In addition, the cetyltrimethylammonium bromide adsorption specific surface area of silica is a value measured according to ASTM D3765-80, and the dibutyl phthalate oil absorption is a value measured according to the method described in JIS K 6221 6.1.2 A method.

The content of silica is preferably 30 parts by mass or more, more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. When the amount is less than 30 parts by mass, there is a tendency that a sufficient wet grip performance improvement effect cannot be obtained. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less. When the amount exceeds 100 parts by mass, dispersibility is deteriorated, and sufficient workability, wear resistance, and durability may not be obtained.

The total content of carbon black, silica and the above inorganic compound is preferably 60 parts by mass or more, more preferably 80 parts by mass or more with respect to 100 parts by mass of the rubber component. The total content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less. When the total content is within the above range, the effects of the present invention can be more suitably obtained.

When silica is blended with the rubber composition of the present invention, it is preferable to use a silane coupling agent together with silica. The silane coupling agent is not particularly limited and can be used in combination with silica in the conventional tire industry. For example, bis (3-triethoxysilylpropyl) polysulfide, bis (2-triethoxysilyl) Ethyl) polysulfide, bis (3-trimethoxysilylpropyl) polysulfide, bis (2-trimethoxysilylethyl) polysulfide, bis (4-triethoxysilylbutyl) polysulfide, bis (4-trimethoxysilylbutyl) polysulfide, etc. These silane coupling agents may be used alone or in combination of two or more. Of these, bis (3-triethoxysilylpropyl) polysulfide and bis (2-triethoxysilylethyl) polysulfide are preferable in terms of both the effect of adding a silane coupling agent and cost, and bis (3-triethoxysilylpropyl) tetrasulfide. Sulfide and bis (2-triethoxysilylethyl) tetrasulfide are more preferred.

The content of the silane coupling agent is preferably 2 parts by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of silica. If it is less than 2 parts by mass, the wear resistance tends to decrease. The content of the silane coupling agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. If it exceeds 20 parts by mass, there is a tendency that an improvement effect commensurate with the increase in cost cannot be obtained.

In the present invention, an amphoteric compound having an acidic functional group and a basic functional group is used. Examples of acidic functional groups include carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, thiosulfonic acid groups (—SSO ₃ H), dithiocarboxylic acid groups (—CSSH), and thioalkylcarboxylic acids having an alkyl group having 1 to 20 carbon atoms. Examples include an acid group (-SRCOOH: R is a linear or branched alkyl group), a phenolic hydroxyl group, and the like, and among them, a thiosulfonic acid group is preferable. Examples of basic functional groups include primary amino groups, secondary amino groups, and tertiary amino groups. The amphoteric compound may be a metal salt of the compound.

As the amphoteric compound, a compound represented by the following formula (I) can be preferably used.

(In the formula (I), R ¹ represents an alkylene group having 2 to 30 carbon atoms, an alkenylene group or an alkynylene group. A represents an acidic functional group. R ² and R ³ are the same or different and represent hydrogen. An atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an alkynyl group, or an alkoxysilyl group having 1 to 20 carbon atoms.The compound represented by the formula (I) may be a metal salt of the compound.)

The functional group part containing nitrogen of the formula (I) binds to carbon black and the above inorganic compound by reacting with oxygen-containing hydrophilic functional groups such as a carboxyl group present on the surface of the carbon black and a hydroxyl group present on the above inorganic compound. The acidic functional group moiety reacts with the double bond of the polymer. Therefore, since the polymer is restrained by the reaction, the exothermic property can be appropriately suppressed. Therefore, thermal sag performance and wear resistance can be improved while maintaining or improving good wet grip performance by carbon black or the above-mentioned inorganic compound blend.

The carbon number of the alkylene group, alkenylene group, and alkynylene group of R ¹ is preferably 2 to 18, more preferably 2 to 12. R ¹ may be linear or branched, and specific examples of the alkylene group include ethylene group, propylene group, butylene group, and specific examples of the alkenylene group include vinylene group, propenylene group, butenylene group, etc. Specific examples of the alkynylene group include an ethynylene group, a propynylene group, and a butynylene group. R ¹ is preferably an alkylene group.

Examples of the acidic functional group for A include those described above. Examples of the alkyl group having 1 to 20 carbon atoms of R ² and R ³ include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkenyl group include a vinyl group, a propenyl group, and a butenyl group. An ethynyl group, a propynyl group, a butynyl group, etc. are mentioned, As a C1-C20 alkoxysilyl group, a triethoxysilyl group, a trimethoxysilyl group, etc. are mentioned. R ² and R ³ are preferably a hydrogen atom.

［式（Ｉ−１）中、ｐは２〜８の整数を表す。式（Ｉ−２）中、ｑは２〜８の整数を表す。Ｍ^ｒ＋は金属イオンを表し、ｒはその価数を表す。］ In the present invention, as the amphoteric compound, it is preferable to use a compound represented by the following formula (I-1) and / or a compound represented by the following formula (I-2).

[In formula (I-1), p represents an integer of 2 to 8. In formula (I-2), q represents an integer of 2 to 8. M ^{r +} represents a metal ion, and r represents its valence. ]

The compound represented by the above formula (I-2) can be produced by any known method. For example, a method of reacting a haloalkylamine with sodium thiosulfate, a method of reacting a potassium salt of phthalimide and a dihaloalkane with a sodium thiosulfate, and hydrolyzing the resulting compound. Can be mentioned.

Specifically, when q is a compound of 6, a method of reacting 6-halohexylamine with sodium thiosulfate, a compound obtained by reacting a potassium salt of phthalimide and 1,6-dihalohexane, and thiosulfuric acid Examples include a method of reacting with sodium and hydrolyzing the obtained compound.

When q is a compound of 3, a method of reacting 3-halopropylamine and sodium thiosulfate, a compound obtained by reacting potassium salt of phthalimide and 1,3-dihalopropane, and sodium thiosulfate And a method of hydrolyzing the resulting compound.

The compound represented by the above formula (I-1) can be produced, for example, by reacting the compound represented by the above formula (I-2) with a protonic acid.

In the present invention, a mixture of compounds represented by formulas (I-1) and (I-2) can also be used. The mixture is obtained by mixing a compound represented by the formula (I-1) and a compound represented by the formula (I-2), a metal-containing hydroxide, carbonate, and carbonic acid represented by the above M. A method of metallizing a part of the compound represented by the formula (I-1) using a hydrogen salt or the like, a method of neutralizing a part of the compound represented by the formula (I-2) using a proton acid Can be manufactured. The compounds represented by the formulas (I-1) and (I-2) thus produced can be removed from the reaction mixture by operations such as concentration and crystallization, and the extracted formula (I-1 ), The compound represented by (I-2) usually contains about 0.1 to 5% of water. In the present invention, only the compound represented by the formula (I-1) or only the compound represented by the formula (I-2) can be used. Furthermore, the compound represented by multiple types of compound represented by Formula (I-1) and the compound represented by Formula (I-2) can also be used together.

In formula (I-1), p represents an integer of 2 to 8, preferably 2 to 5. In formula (I-2), q represents an integer of 2 to 8, and preferably 2 to 5.

As the metal ion represented by ^{Mr +} , lithium ion, sodium ion, potassium ion, cesium ion, cobalt ion, copper ion and zinc ion are preferable, lithium ion, sodium ion and potassium ion are more preferable, and sodium ion is more preferable. . r represents the valence of the metal ion, and is not limited as long as it is a possible range for the metal. In general, r is 1 when the metal ion is an alkali metal ion, 2 or 3 when the metal ion is cobalt ion, an integer of 1 to 3 when the metal ion is copper ion, and 2 when the metal ion is zinc ion. According to the said manufacturing method, although the sodium salt of the compound represented by a formula (I-1) is obtained normally, it can convert into another metal salt by performing a cation exchange reaction.

The median diameter of the compounds represented by the above formulas (I-1) and (I-2) is preferably in the range of 0.05 to 100 μm, more preferably in the range of 1 to 100 μm. The median diameter can be measured by a laser diffraction method.

The compounds represented by the above formulas (I-1) and (I-2) may be used after being previously mixed with a carrier. Examples of the support agent include “inorganic fillers and reinforcing agents” described on pages 510 to 513 of “Rubber Industry Handbook <Fourth Edition>” edited by the Japan Rubber Association. Among them, carbon black, silica, calcined, etc. Clay and aluminum hydroxide are preferred. Although the usage-amount of a support agent is not specifically limited, The range of 10-1000 mass parts is with respect to 100 mass parts of total amounts of the compound represented by the said formula (I-1) and / or (I-2). preferable.

In the rubber composition of the present invention, the content of the amphoteric compound is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass with respect to 100 parts by mass in total of carbon black, silica and the inorganic compound. As mentioned above, More preferably, it is 0.09 mass part or more, Most preferably, it is 0.15 mass part or more. If it is less than 0.01 parts by mass, the wet grip performance, thermal sag performance, and wear resistance may not be improved in a well-balanced manner. Moreover, this content becomes like this. Preferably it is 0.8 mass part or less, More preferably, it is 0.5 mass part or less, More preferably, it is 0.3 mass part or less. If it exceeds 0.8 parts by mass, wet grip performance, thermal sag performance, and abrasion resistance (particularly wet grip performance) may be deteriorated.

In addition to the above components, the rubber composition of the present invention includes compounding agents generally used in the production of rubber compositions, such as zinc oxide, stearic acid, processing aids, various anti-aging agents, oils and the like. Softeners, aromatic petroleum resins, waxes, vulcanizing agents such as sulfur, vulcanization accelerators, and the like can be appropriately blended.

Although it does not specifically limit as a softener which can be used by this invention, For example, mineral oils, such as aromatic oil, a process oil, paraffin oil, will be mentioned if it is oil. Further, as the softening agent, it is more preferable to use a liquid diene polymer as the softening agent from the viewpoint of excellent balance of heat resistance, thermal sag performance, and wet grip performance. These softeners may be used alone or in combination of two or more.

The liquid diene polymer is not particularly limited as long as it is a liquid diene polymer. For example, liquid styrene-butadiene copolymer (rubber), butadiene polymer (rubber), isoprene polymer (rubber), acrylonitrile. Examples thereof include butadiene copolymer (rubber). Among them, a liquid styrene butadiene copolymer (liquid SBR) is preferable because heat resistance, heat sag performance, and wet grip performance can be obtained in a well-balanced manner.

The weight average molecular weight (Mw) of the liquid diene polymer is preferably 1000 or more, more preferably 2000 or more, and still more preferably 3000 or more. If Mw is less than 1000, the wear resistance tends to decrease. The Mw of the liquid diene polymer is preferably 50000 or less, more preferably 40000 or less, and still more preferably 15000 or less. When Mw exceeds 50000, the difference in molecular weight from the rubber component becomes small, and the effect as a plasticizer tends to be hardly exhibited.
In this specification, the weight average molecular weight (Mw) is a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL manufactured by Tosoh Corporation. It is a value obtained by standard polystyrene conversion based on the measured value by SUPERMALTPORE HZ-M).

The content of the liquid diene polymer is preferably 20 parts by mass or more, more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 20 parts by mass, sufficient wet grip performance and thermal sag performance tend not to be obtained. Further, the content of the liquid diene polymer is preferably 120 parts by mass or less, more preferably 90 parts by mass or less, with respect to 100 parts by mass of the rubber component. When it exceeds 120 parts by mass, the wear resistance may be deteriorated.

In the present invention, the amount of oil is preferably 20 to 100 parts by mass, more preferably 50 to 90 parts by mass with respect to 100 parts by mass of the rubber component because the effects of the present invention can be suitably obtained. . Here, the amount of oil contained in the oil-extended rubber is also included in the amount of oil blended.

In this invention, it is preferable to mix | blend aromatic petroleum resin from the reason that the effect of this invention is acquired suitably. Aromatic petroleum resins include phenolic resins, coumarone indene resins, styrene resins, rosin resins, DCPD resins and the like. Among these, a styrene resin is preferable because an effect of the present invention can be more suitably obtained, and an aromatic vinyl polymer obtained by polymerizing α-methylstyrene and / or styrene is more preferable.

In the aromatic vinyl polymer, styrene and α-methylstyrene are used as the aromatic vinyl monomer (unit), and either a homopolymer of each monomer or a copolymer of both monomers is used. Good. The aromatic vinyl polymer is preferably an α-methylstyrene homopolymer or a copolymer of α-methylstyrene and styrene because it is economical, easy to process, and excellent in wet grip performance.

The softening point of the aromatic petroleum resin is preferably 70 ° C. or higher, more preferably 80 ° C. or higher. If it is less than 70 ° C., the wet grip performance tends to deteriorate. The softening point is preferably 140 ° C. or lower, more preferably 120 ° C. or lower, and still more preferably 100 ° C. or lower. When it exceeds 140 ° C., wear resistance and wet grip performance tend to deteriorate.
The softening point of the aromatic petroleum resin is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1: 2001 is measured with a ring and ball softening point measuring device.

The weight average molecular weight (Mw) of the aromatic petroleum resin is preferably 500 or more, more preferably 800 or more. If it is less than 500, there is a tendency that a sufficient improvement effect of wet grip performance cannot be obtained. The weight average molecular weight of the aromatic petroleum resin is preferably 3000 or less, more preferably 2000 or less. If it exceeds 3000, the wear resistance tends to deteriorate.

The content of the aromatic petroleum resin is preferably 2 parts by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 2 parts by mass, the effect of improving wet grip performance may not be sufficiently obtained. Moreover, this content becomes like this. Preferably it is 25 mass parts or less, More preferably, it is 20 mass parts or less. If it exceeds 25 parts by mass, sufficient wet grip performance may not be obtained. In addition, the temperature dependency increases, and the performance change with respect to the temperature change increases, and for example, the thermal sag performance tends to decrease.

Although it does not specifically limit as a vulcanizing agent, Sulfur, an alkylphenol, sulfur chloride condensate, etc. can be used conveniently, and sulfur is preferable.

The sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. The sulfur content is preferably 2 parts by mass or less, more preferably 1 part by mass or less. By adjusting within the above range, the effect of the present invention can be obtained more suitably.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Is mentioned. Of these, thiazole vulcanization accelerators are preferred because of a good balance between scorch and vulcanization speed.

Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and the like. Of these, di-2-benzothiazolyl disulfide is preferred because it has a good balance between scorch and vulcanization speed.

The content of the vulcanization accelerator is preferably 1.5 parts by mass or more, more preferably 2.5 parts by mass or more, and preferably 6 parts by mass or less, more preferably 100 parts by mass of the rubber component. Is 5 parts by mass or less. By adjusting within the above range, the effect of the present invention can be obtained more suitably.

As a method for producing the rubber composition of the present invention, known methods can be used. For example, the above components are kneaded using a rubber kneading apparatus such as an open roll, a Banbury mixer, a closed kneader (kneading step). ), And then vulcanized. Among them, the kneading step is preferably a base kneading step for kneading materials other than the vulcanizing agent and the vulcanization accelerator, and a kneaded product obtained by the base kneading step because the effects of the present invention can be obtained more suitably. It is preferable to include a finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator.

The kneading temperature in the base kneading step is preferably 160 ° C. or higher, more preferably 165 ° C. or higher. By kneading at 160 ° C. or higher, the reactivity of the amphoteric compound is improved, and the effect of improving the performance obtained by blending the amphoteric compound can be exhibited more remarkably. The kneading temperature is preferably 180 ° C. or lower, more preferably 175 ° C. or lower. If it exceeds 180 ° C., gelation of the polymer occurs, and the Mooney viscosity increases, which is not preferable for processing. The kneading time in the base kneading step is not particularly limited, but is usually 30 seconds or more, preferably 1 minute or more. The upper limit of the kneading time is not particularly limited, but is preferably 30 minutes or less.

The finishing kneading step and the vulcanizing step can be performed by a conventionally known method.

The rubber composition of the present invention can be suitably used for a tread of a high performance wet tire.

The high-performance wet tire of the present invention is produced by an ordinary method using the rubber composition. That is, if necessary, a rubber composition containing various additives is extruded in accordance with the shape of a tread or the like at an unvulcanized stage, molded by a normal method on a tire molding machine, After bonding together with the tire member to form an unvulcanized tire, the tire can be manufactured by heating and pressing in a vulcanizer. In addition, the high-performance wet tire in this specification is a pneumatic tire that is particularly excellent in wet grip performance, and includes a concept for a competition tire for a wet road surface used in a competition vehicle.

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 the production examples will be described together.
3-bromopropylamine hydrobromide: manufactured by Kanto Chemical Co., Ltd. Sodium thiosulfate pentahydrate: manufactured by Kanto Chemical Co., Ltd. phthalimide potassium: manufactured by Kanto Chemical Co., Ltd. dimethylformamide: manufactured by Kanto Chemical Co., Ltd. 1,6-dibromohexane: hydrazine monohydrate manufactured by Kanto Chemical Co., Ltd .: manufactured by Kanto Chemical Co., Ltd.

(Production Example 1 S- (3-aminopropyl) thiosulfuric acid (amphoteric compound A))
To a reaction vessel substituted with nitrogen gas, 75 g of 3-bromopropylamine hydrobromide, 85.26 g of sodium thiosulfate pentahydrate, 375 ml of methanol and 375 ml of water were added, and the mixture was refluxed at 70 ° C. for 5 hours. did. After allowing to cool, methanol was removed under reduced pressure. To the residue was added 13.68 g of sodium hydroxide, and the mixture was stirred at room temperature for 1 hour, and then the solvent was removed under reduced pressure. 600 ml of ethanol was added to the obtained residue and refluxed for 1.5 hours. Hot filtration was performed, and the filtrate was concentrated under reduced pressure to obtain crystals. The crystals were taken out by filtration, washed with ethanol, and further washed with hexane. The obtained crystals were vacuum-dried to obtain sodium S- (3-aminopropyl) thiosulfate.
52 g of sodium S- (3-aminopropyl) thiosulfate, 90 ml of water and 5 mol / l hydrochloric acid were added to the reaction vessel substituted with nitrogen gas, and the resulting solution was concentrated under reduced pressure, and the crystals were taken out by filtration. The obtained crystals were vacuum-dried to obtain S- (3-aminopropyl) thiosulfuric acid.

(Production Example 2 S- (6-Aminohexyl) thiosulfuric acid (amphoteric compound B))
To the reaction vessel, 99.2 g of potassium phthalimide and 480 ml of dimethylformamide were added. To this mixture, a mixture of 200 g of 1,6-dibromohexane and 200 ml of dimethylformamide was added dropwise at room temperature. After completion of the dropwise addition, the resulting mixture was heated to 120 ° C. and refluxed for 5 hours. After standing to cool, the solvent was distilled off from the reaction mixture. Ethyl acetate and water were added for liquid separation, and then the organic layer was concentrated. Hexane and ethyl acetate were added to the resulting residue to precipitate crystals. The crystals were taken out and dried under vacuum to obtain N- (6-bromohexyl) phthalimide.
To the reaction vessel, 40 g of N- (6-bromohexyl) phthalimide, 32.0 g of sodium thiosulfate pentahydrate, 200 ml of methanol and 200 ml of water were added, and the mixture was refluxed for 5 hours, allowed to cool and then the reaction mixture. The solvent was distilled off. To the obtained residue, 200 ml of ethanol was added and refluxed for 1.5 hours. Hot filtration was performed, and the filtrate was concentrated under reduced pressure to obtain crystals, and then allowed to stand. The crystals were taken out by filtration, washed with ethanol, and further washed with hexane. The obtained crystals were vacuum-dried to obtain 6-phthalimidohexyl thiosulfate sodium salt.
A reaction vessel purged with nitrogen was charged with 20.0 g (54.7 mmol) of sodium salt of 6-phthalimidohexylthiosulfate and 200 ml of ethanol, and 4.25 g (84.8 mmol) of hydrazine monohydrate was added to the resulting mixture. It was dripped. After completion of the dropwise addition, the resulting mixture was stirred at 70 ° C. for 5 hours, and then ethanol was distilled off under reduced pressure. 100 ml of methanol was added to the residue and refluxed for 1 hour. Crystals were obtained by hot filtration, washed with methanol, and vacuum-dried to obtain S- (6-aminohexyl) thiosulfate sodium salt.
26 g of sodium S- (6-aminohexyl) thiosulfate, 45 ml of water and 5 mol / l hydrochloric acid were added to the reaction vessel substituted with nitrogen gas, the resulting solution was concentrated under reduced pressure, and the crystals were taken out by filtration. The obtained crystals were vacuum-dried to obtain S- (6-aminohexyl) thiosulfuric acid.

The median diameter (50% D) of the amphoteric compounds A to B obtained in the above Production Examples 1 and 2 was measured by a laser diffraction method (measurement procedure is as follows) using a SALD 2000J model manufactured by Shimadzu Corporation. When measured, the median diameter (50% D) was 66.7 μm. The obtained amphoteric compounds A to B were pulverized and their median diameter (50% D) was adjusted to 14.6 μm and used in the following examples.
<Measurement operation>
Amphoteric compounds A to B were dispersed in a mixed solution of a dispersion solvent (toluene) and a dispersant (10% by mass sodium di-2-ethylhexyl sulfosuccinate / toluene solution) at room temperature, and ultrasonic waves were applied to the resulting dispersion. While irradiating, the dispersion was stirred for 5 minutes to obtain a test solution. The test solution was transferred to a batch cell and measured after 1 minute. (Refractive index: 1.70-0.20i)

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
SBR: Nipol 9548 manufactured by Nippon Zeon Co., Ltd. (E-SBR, styrene content: 35% by mass, containing 37.5 parts by mass of oil with respect to 100 parts by mass of rubber solid content)
Carbon black: Seast 9 (N ₂ SA: 142 m ² / g, DBP: 115 ml / 100 g) manufactured by Tokai Carbon Co., Ltd.
Aluminum hydroxide: Heidilite H-43 (average primary particle size: 1 μm) manufactured by Showa Denko KK
Silica: Nippon Sil VN3 (CTAB: 168 m ² / g, DBP: 183 ml / 100 g, N ₂ SA: 177 m ² / g) manufactured by Nippon Silica Kogyo Co., Ltd.
Amphoteric compound (A): S- (3-aminopropyl) thiosulfuric acid (prepared in Production Example 1)
Amphoteric compound (B): S- (6-aminohexyl) thiosulfuric acid (prepared in Production Example 2)
Liquid SBR: RICON100 (Mw: 5000) manufactured by Sartomer
Oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Resin: SYLVARES SA85 manufactured by Arizona chemical (copolymer of α-methylstyrene and styrene (aromatic vinyl polymer), softening point: 85 ° C., Mw: 1000)
Zinc oxide: Zinc oxide stearic acid manufactured by Mitsui Mining & Smelting Co., Ltd .: Anti-aging agent manufactured by NOF Corporation: Antigen 6C (N- (1,3-dimethylbutyl) -N manufactured by Sumitomo Chemical Co., Ltd.) '-Phenyl-p-phenylenediamine)
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Noxeller DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(Examples and Comparative Examples)
In accordance with the formulation shown in Table 1, materials other than sulfur and a vulcanization accelerator were kneaded for 2 minutes at 165 ° C. using a 1.7 L Banbury mixer manufactured by Kobe Steel Co., Ltd. to obtain a kneaded product. . Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes at 80 ° C. using a biaxial open roll to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was molded into a tread shape, and bonded together with other tire members on a tire molding machine, and press vulcanized at 150 ° C. for 30 minutes, and a test tire (tire size: 195 / 65R15).

The following evaluation was performed about the obtained tire for a test. The results are shown in Table 1.

(Wet grip performance evaluation)
The test tire was mounted on a domestic FR vehicle with a displacement of 2000 cc, and the vehicle was run for 10 laps on a wet asphalt road test course. At that time, the test driver evaluated the stability of the control at the time of steering. It shows that it is excellent in the grip performance (wet grip performance) on a wet road surface, so that a numerical value is large.

(Heat sag performance evaluation)
The test tire was mounted on a domestic FR vehicle with a displacement of 2000 cc, and the vehicle was run for 10 laps on a wet asphalt road test course. At that time, the test driver compared and evaluated the stability of control during steering on the third lap of running and the stability of control during steering on the tenth lap of driving, and the comparative example 1 was set to 100 and displayed as an index. It shows that it is excellent in the thermal drooping performance (sustainability of wet grip performance) on a wet road surface so that a numerical value is large.
Thermal sag performance of Comparative Example 1 = (Control stability during steering of the 10th lap of Comparative Example 1) / (Control stability during steering of the 3rd lap of Comparative Example 1)
Thermal sag performance = ((Control stability during steering in the 10th lap in each example) / (Control stability during steering in the 3rd lap in each example)) / (Thermal sag performance in Comparative Example 1) × 100

(Abrasion resistance evaluation)
The test tire was mounted on a 2000 cc domestic FR vehicle, and the vehicle was run on a wet asphalt road test course. The residual groove amount of the tire tread rubber at that time was measured (15 mm when new), and evaluated as wear resistance. The greater the amount of remaining grooves, the better the wear resistance. The amount of remaining grooves in Comparative Example 1 was taken as 100 and displayed as an index. It shows that it is excellent in abrasion resistance, so that a numerical value is large.

From the result of Table 1, the implementation which contains at least 1 sort (s) selected from the group which consists of a natural rubber and a diene type synthetic rubber, carbon black, the amphoteric compound which has an acidic and basic functional group, and a specific inorganic compound The example was able to improve the heat sag performance and wear resistance while maintaining or improving good wet grip performance.

Claims (10)

At least one selected from the group consisting of natural rubber and diene-based synthetic rubber, carbon black, an amphoteric compound having acidic and basic functional groups, and the following formula (Former), the average primary particle size is 10 μm A rubber composition for a high-performance wet tire tread containing the following inorganic compound.
kM ₁・ xSiO _y・ zH ₂ O
(In the formula (A), M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, x Is an integer from 0 to 10, y is an integer from 2 to 5, and z is an integer from 0 to 10.) The rubber composition for a high-performance wet tire tread according to claim 1, wherein the amphoteric compound is a compound represented by the following formula (I).

(In the formula (I), R ¹ represents an alkylene group having 2 to 30 carbon atoms, an alkenylene group or an alkynylene group. A represents an acidic functional group. R ² and R ³ are the same or different and represent a hydrogen atom. Represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an alkynyl group, or an alkoxysilyl group having 1 to 20 carbon atoms.The compound represented by the formula (I) may be a metal salt of the compound.) The rubber composition for a high-performance wet tire tread according to claim 1 or 2, wherein the amphoteric compound is a compound represented by the following formula (I-1) and / or the following formula (I-2).

(In formula (I-1), p represents an integer of 2 to 8. In formula (I-2), q represents an integer of 2 to 8. Mr ⁺ represents a metal ion, and r represents a valence thereof. Represents.) The high-performance wet according to claim 3, wherein the metal ion represented by ^{Mr +} in the formula (I-2) is a lithium ion, a sodium ion, a potassium ion, a cesium ion, a cobalt ion, a copper ion, or a zinc ion. Rubber composition for tire tread. The rubber composition for a high-performance wet tire tread according to any one of claims 1 to 4, wherein the content of styrene-butadiene rubber in 100% by mass of the rubber component is 60 to 100% by mass. The content of carbon black is 10 to 50 parts by mass, the content of silica is 30 to 100 parts by mass, and the content of inorganic compounds is 5 to 30 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition for a high-performance wet tire tread according to any one of the above. The rubber composition for a high performance wet tire tread according to any one of claims 1 to 6, wherein the inorganic compound is an inorganic compound represented by the following formula (B).
Al (OH) _a O _b (Otsu)
(In the formula (B), 0 ≦ a ≦ 3, b = (3-a) / 2.) The rubber composition for a high performance wet tire tread according to any one of claims 1 to 7, wherein the inorganic compound is aluminum hydroxide. The content of amphoteric compounds is 0.01 to 0.8 parts by mass with respect to 100 parts by mass in total of carbon black, silica and inorganic compounds, for high-performance wet tire treads according to any one of claims 1 to 8. Rubber composition. The high performance wet tire produced using the rubber composition for high performance wet tire treads in any one of Claims 1-9.