JP2019026791A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving fuel efficiency and wet grip performance in a well-balanced manner. SOLUTION: The rubber component, silica, glycerin fatty acid ester, and hydrogenated terpene-based resin are contained, and the total content of isoprene-based rubber, butadiene rubber and styrene-butadiene rubber in 100% by mass of the rubber component is 80 mass by mass. % Or more, the content of the silica with respect to 100 parts by mass of the rubber component is 50 parts by mass or more, the content of the glycerin fatty acid ester with respect to 100 parts by mass of the silica is 1 to 20 parts by mass, and the content of the hydrogenated terpene resin. A pneumatic tire using a rubber composition having a mass of 3 parts by mass or more for the tread. [Selection diagram] None

Description

The present invention relates to a pneumatic tire.

As the tire rubber composition, a rubber composition containing a conjugated diene polymer such as polybutadiene or butadiene-styrene copolymer and a filler such as carbon black or silica is used. In recent years, due to increasing interest in environmental issues, there has been a strong demand for lower fuel consumption for automobiles, and rubber compositions used for automobile tires are also required to have excellent fuel efficiency. .

As a method for improving fuel economy, for example, Patent Document 1 proposes a method using a diene rubber (modified rubber) modified with an organosilicon compound containing an amino group and an alkoxy group. However, in recent years, further improvement in fuel economy has been demanded due to an increase in interest in environmental problems. In addition, the required performance includes wet grip performance, etc., but generally there is a relationship contrary to low fuel consumption, and it is difficult to obtain each performance at a high level and in a well-balanced manner.

JP 2000-344955 A

An object of the present invention is to solve the above-mentioned problems and to provide a pneumatic tire that can improve fuel economy and wet grip performance in a well-balanced manner.

The present invention includes a rubber component, silica, glycerin fatty acid ester, and hydrogenated terpene resin, and a total content of isoprene-based rubber, butadiene rubber, and styrene-butadiene rubber in 100% by mass of the rubber component is 80% by mass. % Or more, content of the silica with respect to 100 parts by mass of the rubber component is 50 parts by mass or more, content of the glycerin fatty acid ester with respect to 100 parts by mass of the silica is 1 to 20 parts by mass, content of the hydrogenated terpene resin The present invention relates to a pneumatic tire using a rubber composition having 3 parts by mass or more as a tread.

The hydrogenated terpene resin preferably has a hydrogenation rate of 10% or more.
The glycerin fatty acid monoester content in the glycerin fatty acid ester is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more.

According to the present invention, since it is a pneumatic tire using a rubber composition containing a predetermined rubber, a silica, a glycerin fatty acid ester, and a hydrogenated terpene resin in a predetermined composition for a tread, Low fuel consumption and wet grip performance can be improved in a well-balanced manner.

The pneumatic tire of the present invention has a tread using a rubber composition containing a rubber component containing a predetermined rubber, silica, a glycerin fatty acid ester, and a hydrogenated terpene resin in a predetermined composition. By blending the specified amount of both glycerin fatty acid ester and hydrogenated terpene resin into the specified rubber component and silica-containing compound, the performance balance of fuel efficiency and wet grip performance is significantly improved (synergistically). Is done. The reason why such an effect can be obtained is not necessarily clear, but is presumed as follows.

By hydrogenating the terpene resin to reduce the polarity, the dispersibility of the glycerin fatty acid ester is improved, and good silica dispersibility can be realized due to this. And by improving the silica dispersibility in this way, fuel consumption can be improved, and at the same time, the wet grip performance can be improved by hydrogenation of the terpene resin. Therefore, it is presumed that the performance balance of fuel efficiency and wet grip performance is remarkably (synergistically) improved by the present invention.

(Rubber composition for tread)
Hereinafter, the rubber composition used for the tread will be described.
The rubber composition has a total content of isoprene-based rubber, butadiene rubber and styrene-butadiene rubber in 100% by mass of the rubber component of 80% by mass or more. From the viewpoint of performance balance between low fuel consumption and wet grip performance, the total content is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 100% by mass.

Of the isoprene-based rubber, butadiene rubber (BR), and styrene butadiene rubber (SBR), BR and SBR are preferable, and BR and SBR are more preferably used in combination from the viewpoint of the performance balance.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. As NR, SIR20, RSS # 3, TSR20, etc., IR, IR2200, etc., those commonly used in the tire industry can be used. Modified NR is deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), etc. Modified NR is epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Modified IR Epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more.

The rubber composition may not particularly contain isoprene-based rubber, but when the rubber component includes isoprene-based rubber, the content of isoprene-based rubber in 100% by mass of the rubber component is preferably 1 to 30% by mass, More preferably, it is 1-10 mass%.

The BR is not particularly limited, and any of unmodified BR and modified BR can be used. For example, a high cis content BR, a BR containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), a butadiene rubber synthesized using a rare earth element-based catalyst (rare earth BR), and a tin compound. Commonly used in the tire industry, such as tin-modified butadiene rubber (tin-modified BR). As BR, commercially available products such as Ube Industries, JSR, Asahi Kasei, and Nippon Zeon can be used. These may be used alone or in combination of two or more.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. The content is preferably 70% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less. Within the above range, the performance balance between fuel efficiency and wet grip performance is remarkably improved.

The cis content of BR is preferably 95% by mass or more, more preferably 97% by mass or more.
The cis content can be measured by infrared absorption spectrum analysis.

It does not specifically limit as SBR, For example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), etc. can be used. The SBR may be either a non-modified SBR or a modified SBR, but a modified SBR is preferable from the viewpoint of the performance balance. As commercial products, products manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used.

The content of SBR in 100% by mass of the rubber component is preferably 40% by mass or more, more preferably 60% by mass or more, and still more preferably 65% by mass. The content is preferably 90% by mass or less, more preferably 80% by mass or less. Within the above range, the performance balance between fuel efficiency and wet grip performance is remarkably improved.

The amount of styrene in SBR is preferably 10% by mass or more, more preferably 20% by mass or more. There exists a tendency for favorable wet grip performance to be acquired by making it more than a minimum. The amount of styrene is preferably 50% by mass or less, more preferably 45% by mass or less. By setting it to the upper limit or less, heat generation is reduced, and good fuel economy tends to be obtained.
The amount of styrene is calculated by H ¹ -NMR measurement.

The amount of vinyl in SBR is preferably 25% by mass or more, more preferably 30% by mass or more. There exists a tendency for favorable wet grip performance to be acquired by making it more than a minimum. The vinyl content is preferably 65% by mass or less, more preferably 60% by mass or less. By setting it to the upper limit or less, good wear resistance tends to be obtained.
In the present specification, the vinyl content (1,2-bond butadiene unit content) can be measured by infrared absorption spectrum analysis.

The weight average molecular weight Mw of SBR is preferably 150,000 or more, more preferably 300,000 or more. By setting the lower limit or more, good fuel economy tends to be obtained. The Mw is preferably 1.5 million or less, more preferably 1.2 million or less, and still more preferably 1 million or less. There exists a tendency for favorable workability to be acquired by making it into an upper limit or less.
Mw is based on a value measured by gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ-M manufactured by Tosoh Corporation). It can be measured as a standard polystyrene equivalent value.

As described above, modified SBR can be preferably used in the present invention. However, such modified SBR may be any SBR having a functional group that interacts with a filler such as silica, for example, at least one of SBR. Terminal modified SBR modified with a compound having a functional group (modifier) at the terminal (terminal modified SBR having the functional group at the terminal), main chain modified SBR having the functional group at the main chain, main chain And main chain terminal-modified SBR having the above functional group at the terminal (for example, main chain terminal modified SBR having the above functional group in the main chain and at least one terminal modified with the above modifier) or 2 in the molecule Examples thereof include terminal-modified SBR modified (coupled) with a polyfunctional compound having one or more epoxy groups and introduced with a hydroxyl group or an epoxy group.

Examples of the functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfides. Group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. . These functional groups may have a substituent. Among them, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group ( An alkoxysilyl group having 1 to 6 carbon atoms is preferred.

（式中、Ｒ^１、Ｒ^２及びＲ^３は、同一又は異なって、アルキル基、アルコキシ基、シリルオキシ基、アセタール基、カルボキシル基（−ＣＯＯＨ）、メルカプト基（−ＳＨ）又はこれらの誘導体を表す。Ｒ^４及びＲ^５は、同一又は異なって、水素原子又はアルキル基を表す。Ｒ^４及びＲ^５は結合して窒素原子と共に環構造を形成してもよい。ｎは整数を表す。） As the modified SBR, SBR modified with a compound (modifier) represented by the following formula is particularly preferable.

Wherein R ¹ , R ² and R ³ are the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (—COOH), a mercapto group (—SH) or a derivative thereof. R ⁴ and R ⁵ may be the same or different and each represents a hydrogen atom or an alkyl group, R ⁴ and R ⁵ may be bonded to form a ring structure with a nitrogen atom, and n represents an integer.)

As the modified SBR modified with the compound represented by the above formula (modifier), the polymerization terminal (active terminal) of the styrene butadiene rubber (S-SBR) of solution polymerization is the compound represented by the above formula. Modified SBR (modified SBR described in JP 2010-111753 A) is preferably used.

R ¹ , R ² and R ³ are preferably alkoxy groups (preferably having 1 to 8 carbon atoms, more preferably having 1 to 4 carbon atoms). R ⁴ and R ⁵ are preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. In the case of forming a ring structure with a nitrogen atom bonded to R ⁴ and R ^5, it is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as cyclohexyloxy group) and an aryloxy group (such as phenoxy group and benzyloxy group).

Specific examples of the modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltri Examples include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. Of these, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferable. These may be used alone or in combination of two or more.

As the modified SBR, modified SBR modified with the following compound (modifier) can also be suitably used. Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylol ethane triglycidyl ether, trimethylol propane triglycidyl ether; and two or more of diglycidylated bisphenol A Polyglycidyl ethers of aromatic compounds having the following phenol groups; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxidized liquid polybutadiene; 4,4′-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine and 4,4′-diglycidyl-dibenzylmethylamine; diglycidylaniline, N, N′-diglycidyl-4-glycidyloxyaniline, diglycidyl Luso toluidine, tetraglycidyl meta-xylene diamine, tetraglycidyl diaminodiphenylmethane, tetraglycidyl -p- phenylenediamine, diglycidyl aminomethyl cyclohexane, diglycidyl amino compounds such as tetraglycidyl-1,3-bisaminomethylcyclohexane;

Amino group-containing acid chlorides such as bis- (1-methylpropyl) carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N, N-dimethylcarbamic acid chloride, N, N-diethylcarbamic acid chloride; 1 , 3-bis- (glycidyloxypropyl) -tetramethyldisiloxane, epoxy group-containing silane compounds such as (3-glycidyloxypropyl) -pentamethyldisiloxane;

(Trimethylsilyl) [3- (trimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (triethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (tripropoxysilyl) propyl] sulfide, (trimethylsilyl) [3 -(Tributoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldiethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldioxy) Sulfide group-containing silane compounds such as propoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldibutoxysilyl) propyl] sulfide;

N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane; 4-N, N-dimethylaminobenzophenone, 4-N, N-di-t-butylaminobenzophenone, 4-N, N-diphenylaminobenzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 4,4′-bis (diphenylamino) benzophenone, N, N, N ′, N ′ A (thio) benzophenone compound having an amino group and / or a substituted amino group such as bis- (tetraethylamino) benzophenone; 4-N, N-dimethylaminobenzaldehyde, 4-N, N-diphenylaminobenzaldehyde, 4-N, Amino groups such as N-divinylaminobenzaldehyde And / or a benzaldehyde compound having a substituted amino group; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, N-methyl-5 N-substituted pyrrolidones such as methyl-2-pyrrolidone N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone; N-methyl-ε-caprolactam; N such as N-phenyl-ε-caprolactam, N-methyl-ω-laurylactam, N-vinyl-ω-laurylactam, N-methyl-β-propiolactam, N-phenyl-β-propiolactam, etc. -Substituted lactams;

N, N-bis- (2,3-epoxypropoxy) -aniline, 4,4-methylene-bis- (N, N-glycidylaniline), tris- (2,3-epoxypropyl) -1,3,5 -Triazine-2,4,6-triones, N, N-diethylacetamide, N-methylmaleimide, N, N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3 -Diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N, N-dimethylaminoacetophene, 4-N, N-diethylaminoacetophenone, 1,3-bis (diphenyl) Amino) -2-propanone, 1,7-bis (methylethylamino) -4-heptanone, etc. can be mentioned. Of these, modified SBR modified with alkoxysilane is preferable.
In addition, modification | denaturation by the said compound (modifier) can be implemented by a well-known method.

Rubber components that can be used in addition to isoprene-based rubber, BR, and SBR include diene systems such as acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). Rubber. These may be used alone or in combination of two or more.

The rubber composition preferably contains silica from the viewpoint of performance balance between low fuel consumption and wet grip performance. 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. Examples of commercially available products include products such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama.

The content of silica is 50 parts by mass or more, preferably 70 parts by mass or more, and more preferably 80 parts by mass or more with respect to 100 parts by mass of the rubber component. There exists a tendency for favorable wet grip performance to be acquired by making it more than a minimum. The content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 110 parts by mass or less. By making it below the upper limit, good processability and silica dispersibility tend to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 m ² / g or more, more preferably 80 m ² / g or more, and further preferably 150 m ² / g or more. There exists a tendency for favorable wet grip performance to be acquired by making it more than a minimum. The N ₂ SA is preferably 280 m ² / g or less, more preferably 240 m ² / g or less. By making it below the upper limit, good dispersibility, low fuel consumption and the like tend to be obtained.
The _N 2 SA of silica is a value determined by the BET method in accordance with ASTM D3037-93.

When the rubber composition contains silica, it preferably contains a silane coupling agent.
Examples of the silane coupling agent include any silane coupling agent conventionally used in combination with silica in the rubber industry. Specifically, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) Tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, Bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide, bis (4-trimethoxy) Rilbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, etc. Sulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive's NXT, NXT-Z and other mercapto, vinyltriethoxysilane, vinyltrimethoxysilane and other vinyl, 3-amino Amino-based compounds such as propyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycine such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane Dokishi system, 3-nitro-trimethoxysilane, 3-nitro-propyl triethoxysilane nitro-based, such as, 3-chloropropyl trimethoxy silane, etc. chloro systems such as 3-chloropropyl triethoxy silane. Examples of commercially available products include products such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Amax Co., Ltd., Toray Dow Corning Co., Ltd.

3 mass parts or more are preferable with respect to 100 mass parts of silica, and, as for content of a silane coupling agent, 5 mass parts or more are more preferable. There exists a tendency for the effect by addition to be acquired as it is 3 mass parts or more. The content is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. When the amount is 20 parts by mass or less, an effect commensurate with the blending amount is obtained, and good workability during kneading tends to be obtained.

The rubber composition preferably contains carbon black from the viewpoint of the performance balance. Although it does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 etc. are mentioned. As commercial products, products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Nisshinka Carbon Co., Ltd., Columbia Carbon Co., etc. it can.

The content of carbon black is preferably 5 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. By setting the lower limit or more, sufficient reinforcing properties can be obtained, and good wet grip performance tends to be obtained. The content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. By making it below the upper limit, good rolling resistance tends to be obtained.

Nitrogen adsorption specific surface area _(N 2 SA) of carbon black is preferably ^{20~200m 2 / g, 30~60m 2 /} g is more preferable. By setting the lower limit or more, good wet grip performance and the like tend to be obtained. By making it below the upper limit, there is a tendency that sufficient fuel economy and processability can be obtained.
In this specification, _N 2 SA of carbon black, JIS K 6217-2: determined by 2001.

In the rubber composition, the total content of carbon black and silica is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and preferably 180 parts by mass or less with respect to 100 parts by mass of the rubber component. More preferably, it is 150 mass parts or less, More preferably, it is 120 mass parts or less. If it is in the said range, while being able to obtain favorable wet grip performance and excellent fuel efficiency, the effects of the present invention are sufficiently exhibited.

You may mix | blend inorganic fillers and organic fillers other than carbon black and a silica with the said rubber composition. Examples of the inorganic filler include talc, aluminum hydroxide, aluminum oxide, magnesium hydroxide, magnesium oxide, magnesium sulfate, titanium white, titanium black, calcium oxide, calcium hydroxide, aluminum magnesium oxide, clay, pyrophyllite, bentonite. , Aluminum silicate, magnesium silicate, calcium silicate, aluminum calcium silicate, magnesium silicate, silicon carbide, zirconium, zirconium oxide and the like. Examples of the organic filler include cellulose nanofibers.

The rubber composition contains a glycerin fatty acid ester. A glycerin fatty acid ester is a compound in which a fatty acid is ester-bonded to at least one of the three OH groups of glycerin, and there are glycerin fatty acid monoester, glycerin fatty acid diester, and glycerin fatty acid triester depending on the number of fatty acid bonds. .

The content of the glycerin fatty acid ester is 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more from the viewpoint of improving the dispersibility of the ester with respect to 100 parts by mass of silica. The content is 20 parts by mass or less, preferably 12 parts by mass or less, more preferably 9 parts by mass or less, from the viewpoint of suppressing deterioration in rubber physical properties after vulcanization.

The content of the glycerin fatty acid ester is 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more from the viewpoint of improving the dispersibility of the ester with respect to 100 parts by mass of the rubber component. The content is preferably 20 parts by mass or less, more preferably 11 parts by mass or less, and still more preferably 8 parts by mass or less, from the viewpoint of suppressing deterioration of rubber physical properties after vulcanization.

The fatty acid constituting the glycerin fatty acid ester is preferably 8 to 28 carbon atoms, more preferably 8 to 22 carbon atoms, still more preferably 10 to 18 carbon atoms, and particularly preferably 12 to 18 carbon atoms, from the viewpoint of the performance balance. Of fatty acids. The fatty acid may be any of saturated, unsaturated, straight chain, and branched chain, and in particular, a straight chain saturated fatty acid is preferable. Specific examples of the fatty acid include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, linoleic acid and the like. Lauric acid, palmitic acid, and stearic acid are preferable, and palmitic acid and stearic acid are particularly preferable.

The content of glycerin fatty acid monoester in 100% (mass%) of glycerin fatty acid ester (content of glycerin fatty acid monoester in 100 mass% of the total amount of glycerin fatty acid ester) is preferably 50% or more from the viewpoint of the performance balance. 70% or more is more preferable, and 90% or more is still more preferable. The upper limit is not particularly limited, and may be 100%.

Glycerin fatty acid ester can be manufactured by the esterification method manufactured from glycerol and fatty acid which decomposed | disassembled fats and oils, the transesterification method which used fats and oils and glycerin as a raw material, etc. By using materials derived from natural products as raw materials such as fats and oils and fatty acids, it is possible to obtain a glycerin fatty acid ester with reduced environmental load and the like. Commercial products of glycerin fatty acid esters can also be used, and examples include Leodol MS-60, Excel P-40, Excel 200 and the like manufactured by Kao Corporation. These glycerin fatty acid esters can be blended by arbitrarily selecting one or more kinds.

（式中、ＧはＧＰＣのグリセリン面積、ＭＧはＧＰＣのモノグリセライド面積、ＤＧはＧＰＣのジグリセライド面積、ＴＧはＧＰＣのトリグリセライド面積である。） In the present invention, the monoglyceride content (glycerin fatty acid monoester content) in the glycerin fatty acid ester refers to that obtained by GPC analysis (gel permeation chromatography) according to the following formula: glycerin, monoglyceride, diglyceride It means the area ratio in the GPC analysis of monoglyceride to the total of (glycerin fatty acid diester) and triglyceride (glycerin fatty acid triester).

(In the formula, G is the glycerin area of GPC, MG is the monoglyceride area of GPC, DG is the diglyceride area of GPC, and TG is the triglyceride area of GPC.)

The measurement conditions for GPC are as follows.
[GPC measurement conditions]
GPC measurement was performed using the following measuring apparatus, and THF (tetrahydrofuran) as an eluent was flowed at a flow rate of 0.6 ml / min, and the column was stabilized in a constant temperature bath at 40 ° C. The measurement was performed by injecting 10 μl of a 1% by mass sample solution dissolved in THF.
Standard substance: Monodispersed polystyrene detector: RI-8022 (manufactured by Tosoh Corporation)
Measuring apparatus: HPLC-8220 GPC (manufactured by Tosoh Corporation)
Analytical column: TSK-GEL SUPER H1000 and 2 TSK-GEL SUPER H2000 connected in series (manufactured by Tosoh Corporation)

The rubber composition contains a hydrogenated terpene resin (hydrogenated terpene resin). The hydrogenated terpene resin is a resin obtained by hydrogenating a terpene resin.

As the terpene resin in the hydrogenated terpene tree, a polyterpene resin composed of at least one selected from terpene raw materials such as α-pinene, β-pinene, limonene, dipentene, etc., a fragrance using terpene compound and aromatic compound as raw materials Group-modified terpene resins, terpene phenol resins made from terpene compounds and phenolic compounds (terpene resins not hydrogenated), and the like. Here, examples of the aromatic compound used as a raw material for the aromatic modified terpene resin include styrene, α-methylstyrene, vinyl toluene, and divinyl toluene. Examples of the phenol compound used as a raw material for the terpene phenol resin include phenol, Bisphenol A, cresol, xylenol and the like can be mentioned.

Hydrogenation of the terpene resin can be carried out by a known method. Moreover, a commercial item can also be used for hydrogenated terpene resin. These hydrogenated terpene resins may be used alone or in combination of two or more.

The content of the hydrogenated terpene resin is 3 parts by mass or more, preferably 5 parts by mass or more, more preferably 7 parts by mass or more from the viewpoint of improving silica dispersibility and wet grip performance with respect to 100 parts by mass of silica. It is. The upper limit of the content is not particularly limited, but is preferably 25 parts by mass or less, more preferably 18 parts by mass or less, and still more preferably 13 parts by mass or less from the viewpoint of suppressing deterioration in rubber physical properties after vulcanization.

The content of the hydrogenated terpene resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, more preferably 100 parts by mass of the rubber component from the viewpoint of improving silica dispersibility and improving wet grip performance. 7 parts by mass or more. The upper limit of the content is not particularly limited, but is preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 12 parts by mass or less from the viewpoint of suppressing deterioration in rubber physical properties after vulcanization.

The hydrogenation rate (hydrogenation rate) of the hydrogenated terpene resin is preferably 10% (mol%) or more from the viewpoint of improving silica dispersibility and the performance balance. An upper limit is not specifically limited, What is necessary is just to select suitably.
In addition, a hydrogenation rate is a value calculated by the following formula from each integrated value of a double bond-derived peak by ¹ H-NMR (proton NMR), and means a hydrogenation rate of a double bond.
(Hydrogenation rate [%]) = {(A−B) / A} × 100
A: Integrated value of double bond peak before hydrogenation B: Integrated value of double bond peak after hydrogenation

The softening point of the hydrogenated terpene resin is preferably 75 ° C. or higher, more preferably 80 ° C. or higher, and still more preferably 90 ° C. or higher, from the viewpoint of ease of handling. Moreover, from a viewpoint of workability and the dispersibility improvement of a rubber component and a filler, 150 degrees C or less is preferable, 140 degrees C or less is more preferable, and 130 degrees C or less is still more preferable. The softening point of the resin in the present invention is 1 by a plunger while heating 1 g of resin as a sample at a heating rate of 6 ° C./min using a flow tester (manufactured by Shimadzu Corporation, CFT-500D). A load of .96 MPa was applied, the nozzle was extruded from a nozzle having a diameter of 1 mm and a length of 1 mm, and the plunger drop amount of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was obtained.

The glass transition temperature (Tg) of the hydrogenated terpene resin is preferably 90 ° C. or lower, more preferably 70 ° C. or lower, from the viewpoint of preventing the glass transition temperature of the rubber composition from becoming high and deteriorating durability. 60 ° C. or lower is more preferable, 50 ° C. or lower is particularly preferable, and 40 ° C. or lower is most preferable. In addition, the lower limit of Tg is preferably 0 ° C. or higher, more preferably 5 ° C. or higher, and still more preferably 10 ° C. or higher, from the viewpoint of ensuring volatility.

The SP value of the hydrogenated terpene resin is preferably 8.00 to 13.00, and preferably 8.00 from the viewpoint that the silica dispersibility improving effect and the performance balance improving effect can be obtained by the combined use with the glycerin fatty acid ester. ~ 11.00 is more preferable, and 8.00 to 10.00 is still more preferable. The SP value means a solubility parameter calculated by the Hoy method based on the structure of the compound. The Hoy method is, for example, K.K. L. Hoy “Table of Solubility Parameters”, Solvent and Coatings Materials Research and Development Department, Union Carbites Corp. (1985).

The rubber composition preferably contains oil together with the glycerin fatty acid ester and the hydrogenated terpene resin from the viewpoint of the performance balance.

As the oil, for example, process oil, vegetable oil, or a mixture thereof can be used. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. Specific examples of the paraffinic process oil include PW-32, PW-90, PW-150, and PS-32 manufactured by Idemitsu Kosan Co., Ltd. Specific examples of the aroma-based process oil include AC-12, AC-460, AH-16, AH-24, and AH-58 manufactured by Idemitsu Kosan Co., Ltd. As vegetable oils and fats, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut hot water, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Commercial products include, for example, Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd. ) Etc. can be used. These may be used alone or in combination of two or more. Among these, paraffinic process oil is preferable because the effects of the present invention can be suitably obtained.

The total content of oil, glycerin fatty acid ester and hydrogenated terpene resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. . The total content is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. By making it within the above range, the performance balance is remarkably improved.

The rubber composition is preferably blended with wax from the viewpoint of crack resistance, ozone resistance and the like.

The wax is not particularly limited, and examples thereof include petroleum wax and natural wax. A synthetic wax obtained by refining or chemically treating a plurality of waxes can also be used. These waxes may be used alone or in combination of two or more.

Examples of petroleum waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are derived from non-petroleum resources. For example, plant waxes such as candelilla wax, carnauba wax, wood wax, rice wax, jojoba wax; beeswax, lanolin, whale wax, etc. Animal waxes; mineral waxes such as ozokerite, ceresin, petrolactam; and purified products thereof. As a commercial item, products, such as Ouchi Shinsei Chemical Co., Ltd., Nippon Seiwa Co., Ltd., Seiko Chemical Co., Ltd., can be used, for example.

The content of the wax is preferably 0.3 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. By making the lower limit or more, sufficient ozone resistance tends to be obtained. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less. By making it below the upper limit, there is a tendency that the balance between ozone resistance and cost is improved.

The rubber composition preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance and the like.

Although it does not specifically limit as anti-aging agent, Diphenylamine type anti-aging agents, such as naphthylamine type anti-aging agents, such as phenyl-alpha-naphthylamine; Octylated diphenylamine, 4,4'-bis (alpha, alpha'-dimethylbenzyl) diphenylamine N-isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylene P-phenylenediamine-based antioxidants such as diamines; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methyl Monophenolic antioxidants such as phenol and styrenated phenol; tetrakis- [methylene-3- (3 ', 5'-di-t Butyl-4'-hydroxyphenyl) propionate] bis methane, tris, and the like polyphenolic antioxidants. Of these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 More preferred is a polymer of 1,2-dihydroquinoline. Examples of commercially available products include Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flexis Co., Ltd.

The content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and still more preferably 2.0 parts by mass or more with respect to 100 parts by mass of the rubber component. By making the lower limit or more, sufficient ozone resistance tends to be obtained. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less. There exists a tendency for the favorable external appearance of a tire to be acquired by making it into an upper limit or less.

The rubber composition preferably contains stearic acid. The content of stearic acid is preferably 0.5 to 10 parts by mass or more, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of the performance balance.

As stearic acid, conventionally known ones can be used. For example, products such as NOF Corporation, NOF, Kao Corporation, Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd. can be used. .

The rubber composition preferably contains zinc oxide. The content of zinc oxide is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component, from the viewpoint of the performance balance.

In addition, as a zinc oxide, a conventionally well-known thing can be used, for example, Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. Can be used.

In the rubber composition, sulfur is preferably blended in that an appropriate cross-linked chain is formed in the polymer chain and a good performance balance is imparted.

The sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and still more preferably 1.0 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, and still more preferably 3.0 parts by mass or less. By making it within the above range, the effect of the present invention tends to be sufficiently obtained.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur that are generally used in the rubber industry. As commercial products, products such as Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nihon Kiboshi Kogyo Co., Ltd., Hosoi Chemical Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The rubber composition preferably contains a vulcanization accelerator.
The content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization speed and crosslinking density, but is usually 0.3 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The amount is preferably 0.5 to 7 parts by mass.

There is no restriction | limiting in particular in the kind of vulcanization accelerator, The normally used thing can be used. Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), Tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N′-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfena De-based vulcanization accelerator; diphenylguanidine, it may be mentioned di-ortho-tolyl guanidine, guanidine-based vulcanization accelerators such as ortho tri ruby guanidine. These may be used alone or in combination of two or more. Of these, sulfenamide vulcanization accelerators and guanidine vulcanization accelerators are preferable from the viewpoint of the performance balance.

In addition to the above components, the rubber composition may be appropriately mixed with a compounding agent generally used in the tire industry, such as a release agent.

As a method for producing the rubber composition, a known method can be used. For example, the components can be produced by a method of kneading each component using a rubber kneading device such as an open roll or a Banbury mixer and then vulcanizing. .

As the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30. Second to 30 minutes, preferably 1 to 30 minutes. In the final kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. Further, a composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200 ° C, preferably 140 to 180 ° C.

(Pneumatic tire)
The pneumatic tire of the present invention can be 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. A vulcanized tire can be formed. A tire is obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

The pneumatic tire of the present invention can be used as, for example, passenger car tires, truck / bus tires, motorcycle tires, and high-performance tires (competition tires, etc.).

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.
BR: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass)
Modified SBR: Production Example 1
Carbon Black: Show Black N550 (N ₂ SA: 42 m ² / g) manufactured by Cabot Japan
Silica: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 175 m ² / g)
Silane coupling agent: Si75 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa
Wax: Sunnock wax oil manufactured by Ouchi Shinsei Chemical Co., Ltd .: Process oil PW-32 (paraffinic process oil) manufactured by Idemitsu Kosan Co., Ltd.
AMS resin: SA85 manufactured by Arizona Chemical Co. (SP value 9.1, softening point 85 ° C., Tg 43 ° C.)
Hydrogenated polyterpene resin 1: P85 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenation rate 10% or more, SP value 8.36, softening point 85 ° C., Tg 43 ° C.)
Hydrogenated polyterpene resin 2: P105 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenation rate 10% or more, SP value 8.36, softening point 105 ° C., Tg 55 ° C.)
Hydrogenated polyterpene resin 3: P125 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenation rate 10% or more, SP value 8.36, softening point 125 ° C., Tg 67 ° C.)
Hydrogenated polyterpene resin 4: P150 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenation rate 10% or more, SP value 8.36, softening point 150 ° C., Tg 90 ° C.)
Hydrogenated aromatic modified terpene resin 1: M105 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenation rate 10% or more, SP value 8.52, softening point 105 ° C., Tg: 55)
Hydrogenated aromatic modified terpene resin 2: M125 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenation rate 10% or more, SP value 8.52, softening point 125 ° C., Tg 65 ° C.)
Non-hydrogenated polyterpene resin: PX800 manufactured by Yashara Chemical Co., Ltd. (hydrogenation rate 0%, SP value of 8.42, softening point 80 ° C., Tg 42 ° C.)
Glycerin fatty acid ester 1: Exel P-40S manufactured by Kao Corporation (monoester content 50 to 60% by mass, fatty acid: C16 content 30 to 40%, C18 content 50 to 60%)
Glycerin fatty acid ester 2: EXO 200 manufactured by Kao Corporation (C18F1 monoester content 79% by mass, fatty acid: C16 content 20-30%, C18 content 50-60%)
Glycerin fatty acid ester 3: Rheodor MS-60 (glycerol monostearate, monoester content: 100% by mass) manufactured by Kao Corporation
Anti-aging agent 1: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Anti-aging agent 2: Nocrack 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Stearic acid: Sulfur stearate manufactured by NOF Corporation: Powdered sulfur oxide manufactured by Tsurumi Chemical Co., Ltd. Zinc oxide: Zinc Hua No. 1 vulcanization accelerator manufactured by Mitsui Mining & Smelting Co., Ltd. NOxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide)
Vulcanization accelerator DPG: Noxeller D (1,3-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(Production Example 1)
Under a nitrogen atmosphere, put 3- (N, N-dimethylamino) propyltrimethoxysilane (3-dimethylaminopropyltrimethoxysilane) (manufactured by Amax Co.) into a 100 ml volumetric flask, and then add anhydrous hexane (Kanto Chemical Co., Ltd.) )) Was added to prepare a terminal modifier.
N-Hexane, styrene (manufactured by Kanto Chemical Co., Inc.), butadiene, and tetramethylethylenediamine were added to a pressure-resistant container sufficiently purged with nitrogen, and the temperature was raised to 40 ° C. Next, after adding butyl lithium (manufactured by Kanto Chemical Co., Inc.), the temperature was raised to 50 ° C. and stirred. Subsequently, a silicon tetrachloride / hexane solution was added and stirred. Further, the terminal modifier was added and stirred. After adding methanol (manufactured by Kanto Chemical Co., Ltd.) in which 2,6-tert-butyl-p-cresol (manufactured by Ouchi Shinsei Chemical Co., Ltd.) is dissolved in the reaction solution, the reaction solution is a stainless steel container containing methanol. The aggregates were collected in The obtained aggregate was dried under reduced pressure for 24 hours to obtain a modified SBR.
The resulting modified SBR had a styrene content of 35 mass%, a vinyl content of 50 mass%, and a weight average molecular weight Mw of 700,000.

According to the formulation shown in Table 1, chemicals other than sulfur and a vulcanization accelerator were kneaded using a 1.7 L Banbury mixer until the temperature reached 180 ° C. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded until reaching 105 ° C., thereby obtaining an unvulcanized rubber composition. Next, the obtained unvulcanized rubber composition was press vulcanized at 160 ° C. for 15 minutes to obtain a vulcanized rubber composition.
Further, the obtained unvulcanized rubber composition is molded into a tread shape and bonded together with other tire members on a tire molding machine to form an unvulcanized tire, which is vulcanized at 170 ° C. for 12 minutes, and tested. Tires (size: 195 / 65R15) were manufactured.

The obtained vulcanized rubber composition was evaluated as follows, and the results are shown in Table 1 (reference comparative example: comparative example 1).

<Hardness measurement>
In accordance with JIS K6253, the hardness of each vulcanized rubber composition was measured (Shore-A measurement) using a hardness meter at a temperature of 25 ° C., and an index with the hardness of the reference comparative example as 100 (the hardness / each compounding / The hardness of the reference comparative example × 100) was calculated. It shows that it is excellent in steering stability, so that an index | exponent is large. The hardness index was set to 98 or more.

<Rolling resistance>
Using a rolling resistance tester, the rolling resistance when the test tire was run at a rim (15 × 6JJ), internal pressure (230 kPa), load (3.43 kN), speed (80 km / h) was measured, and the standard The index was expressed as an index when the comparative example was 100. Larger values indicate lower rolling resistance and better fuel efficiency. The rolling resistance index was set to 100 or more.

<Wet grip performance>
A test tire was mounted on all wheels of a vehicle (domestic FF2000cc), and a braking distance from an initial speed of 100 km / h was determined on a wet asphalt road surface. The results are expressed as an index with the reference comparative example being 100, and the larger the number, the better the wet grip performance. The index was calculated by the following formula. The target wet grip performance index was 105 or more.
Wet grip performance = (braking distance of reference comparative example) / (braking distance of each formulation) × 100

<Elongation at break>
Test pieces were prepared from each vulcanized rubber composition using a No. 3 dumbbell mold, and a tensile test was carried out at room temperature according to JIS K 6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”. The elongation at break EB (%) was measured, and an index (EB of each formulation / EB × 100 of the reference comparative example) with the EB of the reference comparative example being 100 was calculated. It shows that it is excellent in fracture strength, so that an index | exponent is large. The EB index was set to 100 or more.

In the rubber composition of the example in which both a glycerin fatty acid ester and a hydrogenated terpene resin are used in combination containing a predetermined rubber component and silica, the handling stability, fuel efficiency, wet grip performance, breaking strength (EB) The performance balance was significantly improved. Moreover, it became clear from Example 1 and Comparative Examples 2-4 that these performance balances are synergistically improved by combined use of glycerin fatty acid ester and hydrogenated terpene resin.

Claims (5)

Including a rubber component, silica, glycerin fatty acid ester, and hydrogenated terpene resin,
The total content of isoprene-based rubber, butadiene rubber and styrene butadiene rubber in 100% by mass of the rubber component is 80% by mass or more,
The silica content with respect to 100 parts by mass of the rubber component is 50 parts by mass or more,
A pneumatic tire using, as a tread, a rubber composition in which the content of the glycerin fatty acid ester is 1 to 20 parts by mass and the content of the hydrogenated terpene resin is 3 parts by mass or more with respect to 100 parts by mass of the silica. The pneumatic tire according to claim 1, wherein the hydrogenated terpene resin has a hydrogenation rate of 10% or more. The pneumatic tire according to claim 1 or 2, wherein the glycerin fatty acid monoester content in the glycerin fatty acid ester is 50% or more. The pneumatic tire according to any one of claims 1 to 3, wherein the glycerin fatty acid monoester content in the glycerin fatty acid ester is 70% or more. The pneumatic tire according to any one of claims 1 to 4, wherein the glycerin fatty acid monoester content in the glycerin fatty acid ester is 90% or more.