JP2023155706A - Rubber composition and tire - Google Patents

Abstract

To provide a rubber composition and tire having excellent overall performance of fuel efficiency and wet grip performance.SOLUTION: There is provided a rubber composition which comprises a modified polymer modified with a divalent phenol compound and silica.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a rubber composition and a tire.

Various polymers are used in products such as tires, and it is desired that the polymers provide various performances.

An object of the present invention is to solve the above-mentioned problems and provide a rubber composition and tire that have excellent overall performance in terms of fuel efficiency and wet grip performance.

The present invention relates to a rubber composition containing a modified polymer modified with a dihydric phenol compound and silica.

According to the present invention, since the rubber composition contains a modified polymer modified with a dihydric phenol compound and silica, it is possible to improve fuel efficiency and wet grip performance.

This is an example of a synthesis example showing a route in which a dihydric phenol compound and a polymer react to synthesize a modified polymer.

<Rubber composition>
The present invention is a rubber composition containing a modified polymer modified with a dihydric phenol compound and silica.

The reason why the above-mentioned effects are obtained is not necessarily clear, but it is presumed to be due to the following mechanism.
Polymers modified with dihydric phenol compounds such as catechol have two hydroxyl groups, and these hydroxyl groups tend to bond or interact with silica, which is thought to function to improve the dispersibility of silica. It will be done. In addition, since it has a structure in which a planar benzene ring and two hydroxyl groups are connected, it is thought that when it interacts with silica, it can easily reduce its mobility and reduce heat generation.
Furthermore, dihydric phenol compounds such as catechol have underwater tackiness, and it is thought that wet grip performance is further improved by imparting underwater tackiness to the polymer.
Therefore, it is presumed that the overall performance of fuel efficiency and wet grip performance is improved.

(modified polymer)
In the modified polymer, the dihydric phenol compound refers to a compound having two phenolic --OH groups.

（前記式（１）～（３）中、Ｒ^１～Ｒ^４は、互いに独立して、水素原子、炭化水素基、ハロゲン原子、ヒドロキシル基、アセチル基、置換基を有してもよいアミノ基もしくは塩酸塩、置換基を有してもよいスルホン酸基もしくはスルホン酸塩基、チオール基、ニトロ基、シアノ基、カルボニル基、カルボキシル基またはハロゲン原子、ヒドロキシル基、カルボキシル基もしくはアミノ基で置換されていてもよい、炭素数１～２０のアルキル基、炭素数１～２０のアルコキシル基、炭素数１～２０のアルキルチオ基、炭素数２～２０のアルケニル基、炭素数２～２０のアルキニル基、炭素数６～２０のアリール基もしくは炭素数２～２０のヘテロアリール基を表す。） The dihydric phenol compound is not particularly limited as long as it is a compound having two phenolic -OH groups, such as a catechol compound represented by the following formula (1), a resorcinol represented by the following formula (2), etc. and hydroquinone compounds represented by the following formula (3).

(In the above formulas (1) to (3), R ¹ to R ⁴ are each independently a hydrogen atom, a hydrocarbon group, a halogen atom, a hydroxyl group, an acetyl group, an amino group which may have a substituent) or hydrochloride, a sulfonic acid group or sulfonic acid group which may have a substituent, a thiol group, a nitro group, a cyano group, a carbonyl group, a carboxyl group, or a halogen atom, a hydroxyl group, a carboxyl group, or an amino group. Alkyl group having 1 to 20 carbon atoms, alkoxyl group having 1 to 20 carbon atoms, alkylthio group having 1 to 20 carbon atoms, alkenyl group having 2 to 20 carbon atoms, alkynyl group having 2 to 20 carbon atoms, carbon Represents an aryl group having 6 to 20 carbon atoms or a heteroaryl group having 2 to 20 carbon atoms.)

Examples of hydrocarbon groups include alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups, and cyclo Cycloalkyl groups with 3 to 8 carbon atoms such as propyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; alkyl groups with 1 to 6 carbon atoms such as phenethyl and phenylpropyl; Examples include an aralkyl group to which an aryl group is bonded. Note that these groups include various isomers. R ¹ to R ⁴ may be bonded to each other to form a ring, and the ring formed by bonding is, for example, a methylene dioxy ring containing an alkylene group having 1 to 3 carbon atoms, an ethylene dioxy ring, etc. Examples include oxy ring and propylene dioxy ring.

Specific examples of the halogen atoms include fluorine, chlorine, bromine, or iodine atoms, or (fluoro)alkylsulfonyloxy groups such as methanesulfonyloxy, trifluoromethanesulfonyloxy, and nonafluorobutanesulfonyloxy; benzene Examples include aromatic sulfonyloxy groups such as a sulfonyloxy group and a toluenesulfonyloxy group.

Examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, and tert-butyl group.

Examples of the alkoxyl group having 1 to 20 carbon atoms include alkoxyl groups having 1 to 20 carbon atoms such as methoxyl group, ethoxyl group, and propoxyl group. Note that these groups include various isomers.

Examples of the alkylthio group having 1 to 20 carbon atoms include alkylthio groups having 1 to 20 carbon atoms such as methylthio group, ethylthio group, and propylthio group. Note that these groups include various isomers.

Specific examples of alkenyl groups having 2 to 20 carbon atoms include ethenyl group, n-1-propenyl group, n-2-propenyl group, 1-methylethenyl group, n-1-butenyl group, n-2-butenyl group, n-3-butenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, 1-methyl-1-propenyl group, 1-methyl-2-propenyl group, n- Examples include 1-pentenyl group, n-1-decenyl group, and n-1-eicosenyl group.

Specific examples of alkynyl groups having 2 to 20 carbon atoms include ethynyl group, n-1-propynyl group, n-2-propynyl group, n-1-butynyl group, n-2-butynyl group, n-3-butynyl group. group, 1-methyl-2-propynyl group, n-1-pentynyl group, n-2-pentynyl group, n-3-pentynyl group, n-4-pentynyl group, 1-methyl-n-butynyl group, 2- Methyl-n-butynyl group, 3-methyl-n-butynyl group, 1,1-dimethyl-n-propynyl group, n-1-hexynyl group, n-1-decynyl group, n-1-pentadecynyl group or n- Examples include 1-eicosynyl group.

Specific examples of the aryl group having 6 to 20 carbon atoms include phenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-phenanthryl group, 2-phenanthryl group. group, 3-phenanthryl group, 4-phenanthryl group, or 9-phenanthryl group.

Specific examples of heteroaryl groups having 2 to 20 carbon atoms include 2-thienyl group, 3-thienyl group, 2-furanyl group, 3-furanyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 3-isoxazolyl group, 4-isoxazolyl group, 5-isoxazolyl group, 2-thiazolyl group, 4-thiazolyl group, 5-thiazolyl group, 3-isothiazolyl group, 4-isothiazolyl group, 5-isothiazolyl group, 2-imidazolyl group, Examples include 4-imidazolyl group, 2-pyridyl group, 3-pyridyl group, and 4-pyridyl group.

Among the dihydric phenol compounds, the catechol compound represented by the formula (1) is preferable from the viewpoint of obtaining more effects. Suitable examples of the catechol compound include compounds represented by the following formulas (1a), (1b), and (1c), among which compounds represented by the following formulas (1b) and (1c). is preferable, and a compound represented by the following formula (1b) is more preferable.

In the present invention, in addition to the compounds represented by formulas (1a) to (1c), examples of the catechol compounds include dopamine, adrenaline, noradrenaline, dihydroxyphenylacetic acid, dihydroxyhydrocinnamic acid, dihydroxyacetophenone, and dihydroxybenzoic acid. , dihydroxybenzyl alcohol, methoxycatechol, nitrocatechol, Tyrone, and the like. Among them, dopamine, adrenaline, noradrenaline, dihydroxyphenylacetic acid, and dihydroxyhydrocinnamic acid are preferred from the viewpoint of obtaining more effects.

The reason why more effects are obtained when using the catechol compounds, particularly dopamine, etc. is not necessarily clear, but it is presumed to be due to the following mechanism.
By using a techol compound that has underwater tackiness, underwater tackiness is imparted to the polymer, which is thought to improve wet grip performance. Therefore, it is presumed that the overall performance of fuel efficiency and wet grip performance is further improved.

The polymer constituting the skeleton of the modified polymer is not particularly limited, and any polymer can be used.

The polymer may be an unmodified polymer or a modified polymer.
The modified polymer may be any polymer having a functional group, for example, a terminal-modified polymer (having the above-mentioned functional group at the end) in which at least one end of the polymer is modified with a compound (modifier) having the above-mentioned functional group. Terminal-modified polymers), main chain-modified polymers having the above-mentioned functional groups in the main chain, main-chain-terminated polymers having the above-mentioned functional groups in the main chain and ends (for example, main chain-terminated polymers having the above-mentioned functional groups in the main chain, and at least one The main chain end-modified polymer whose end is modified with the above-mentioned modifier) or a terminal-modified polymer whose hydroxyl group or epoxy group is introduced by modification (coupling) with a polyfunctional compound having two or more epoxy groups in the molecule. Examples include polymers.

Examples of the above 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, and disulfide groups. 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. . Note that these functional groups may have a substituent. Among these, from the viewpoint of reactivity with the phenylboronic acid compound represented by the formula (1), amino groups, epoxy groups, carboxyl groups, etc. are preferable.

Examples of the above-mentioned polymers include polymers having carbon-carbon double bonds.
Examples of the polymer having a carbon-carbon double bond include polymers such as diene rubber. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). ), etc. Other examples include polymers such as butyl rubber and fluororubber. Among these, from the viewpoint of reactivity with the dihydric phenol compound, fuel efficiency, wet grip performance, etc., isoprene-based rubber, NBR, BR, and SBR are preferred, isoprene-based rubber, NBR, and SBR are more preferred, and isoprene-based rubber, NBR, and SBR are more preferred. Rubber is more preferred. These may be used alone or in combination of two or more.

Although it is not necessarily clear why more effects are obtained when isoprene rubber, NBR, BR, or SBR is used, it is presumed to be due to the following mechanism.
By using a modified polymer (modified rubber) whose skeleton is composed of isoprene rubber, NBR, BR, and SBR, it is easy to mix with other rubber components, and is partially crosslinked by double bonds, which reduces heat generation caused by silica. Since it is possible to reduce the amount of water more easily, it is possible to impart excellent wet grip performance and fuel efficiency to the tire, and it is presumed that these overall performances are further improved.

Isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. As the NR, for example, those commonly used in the rubber industry, such as SIR20, RSS#3, and TSR20, can be used. The IR is not particularly limited, and for example, those commonly used in the rubber industry, such as IR2200, can be used. Modified NR includes deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), etc.; modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. As shown in these examples, the isoprene rubber may be an unmodified isoprene rubber or a modified isoprene rubber (such as ENR). These may be used alone or in combination of two or more.

From the viewpoint of reactivity with the dihydric phenol compound, the isoprene rubber is preferably a modified isoprene rubber. Examples of the functional groups added to the modified isoprene rubber include the aforementioned functional groups, and among them, carboxyl groups, An amino group and an epoxy group are preferred.

The BR is not particularly limited, and for example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth catalyst (rare earth BR), etc. can be used. These may be used alone or in combination of two or more. Among these, high-cis BR having a cis content of 90% by mass or more is preferred because it improves wear resistance. The BR may be unmodified BR or modified BR (such as carboxylic acid-modified BR). These may be used alone or in combination of two or more.

From the viewpoint of reactivity with the dihydric phenol compound, BR is preferably modified BR. Examples of the functional groups added to the modified BR include the above-mentioned functional groups, and among them, from the viewpoint of reactivity with the dihydric phenol compound, fuel efficiency, wet grip performance, etc., carboxyl groups and amino groups are added. , epoxy groups are preferred.

As the BR, for example, products manufactured by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

The SBR is not particularly limited, and for example, emulsion polymerized styrene butadiene rubber (E-SBR), solution polymerized styrene butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more. The SBR may be unmodified SBR or modified SBR (such as carboxylic acid modified SBR). These may be used alone or in combination of two or more.

From the viewpoint of reactivity with the dihydric phenol compound, SBR is preferably modified SBR. Examples of the functional groups added to the modified SBR include the above-mentioned functional groups, and among them, from the viewpoint of reactivity with the dihydric phenol compound, fuel efficiency, wet grip performance, etc., carboxyl groups and amino groups are added. , epoxy groups are preferred.

The amount of styrene in SBR is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more. Further, the amount of styrene is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less. Within the above range, tire performance such as wet grip performance tends to be better.
Note that in this specification, the styrene content of SBR is calculated by ¹ H-NMR measurement.

The amount of vinyl in SBR is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more. The amount of vinyl is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less. Within the above range, tire performance such as wet grip performance tends to be better.
Note that the vinyl content (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectroscopy.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used.

Examples of the above-mentioned polymer include polymers (rubber components) such as diene rubber, butyl rubber, and fluororubber, as well as liquid polymers (liquid resin, liquid diene polymer, liquid farnesene type) that are in a liquid state at room temperature (25°C). polymers, modified resins thereof, modified polymers, etc.) can also be used. Among these, liquid diene polymers are preferred from the viewpoints of reactivity with the dihydric phenol compound, fuel efficiency, wet grip performance, and the like. These may be used alone or in combination of two or more.
As described later, in the rubber composition of the present invention, the "rubber component" is a component that contributes to crosslinking, and is generally a polymer having a weight average molecular weight (Mw) of 10,000 or more, which is extracted with acetone. Even in the case of the liquid polymer, components that fall under the definition of "rubber component" are considered to be "rubber components" in the present invention.

From the viewpoint of reactivity with the dihydric phenol compound, the liquid polymer is preferably a modified liquid polymer. Examples of the functional groups added to the modified liquid polymer include the above-mentioned functional groups, and among them, carboxyl groups, amino and epoxy groups are preferred.

Liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5/C9 resins, and dicyclopentadiene (DCPD) resins. , coumaron indene resins (including coumaron and indene resins), phenol resins, olefin resins, polyurethane resins, acrylic resins, and the like. Moreover, these hydrogenated substances can also be used.

Examples of liquid diene-based polymers include liquid styrene-butadiene copolymer, liquid butadiene polymer, liquid isoprene polymer, liquid styrene-isoprene copolymer, liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), which is in a liquid state at 25°C. ), liquid styrene isoprene styrene block copolymer (liquid SIS block polymer), liquid farnesene polymer, liquid farnesene butadiene copolymer, and the like. These may have their terminals or main chains modified with polar groups. Moreover, these hydrogenated substances can also be used. Among these, liquid styrene-butadiene copolymers, liquid butadiene polymers, and liquid isoprene polymers are preferred from the viewpoint of reactivity with the dihydric phenol compound, fuel efficiency, wet grip performance, etc., and liquid isoprene polymers are more preferred. preferable.

The liquid farnesene-based polymer is a polymer obtained by polymerizing farnesene, and has a constituent unit based on farnesene. Farnesene includes α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1 , 6,10-dodecatriene), but (E)-β-farnesene having the following structure is preferred.

The liquid farnesene-based polymer may be a farnesene homopolymer (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). These may be used alone or in combination of two or more. Among these, a copolymer of farnesene and a vinyl monomer is preferred.

Examples of vinyl monomers include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5- t-Butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethyl Styrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, Examples include aromatic vinyl compounds such as vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and diphenylethylene containing a tertiary amino group, and conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Among them, butadiene is preferred. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferable.

In the farnesene-vinyl monomer copolymer, the mass-based copolymerization ratio of farnesene and vinyl monomer (farnesene/vinyl monomer) is preferably 40/60 to 90/10.

As the liquid farnesene polymer, one having a weight average molecular weight (Mw) of 3,000 to 300,000 can be suitably used. The Mw of the liquid farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less.

In this specification, weight average molecular weight (Mw) refers to gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL manufactured by Tosoh Corporation). It can be determined by standard polystyrene conversion based on the measured value by SUPERMULTIPORE HZ-M).

As the above-mentioned polymer, a resin (resin in a solid state at room temperature (25° C.)) can also be used.
Examples of the above resins (resins that are solid at room temperature (25°C)) include aromatic vinyl polymers that are solid at room temperature (25°C), coumaron indene resin, coumaron resin, indene resin, phenol resin, and rosin resin. , petroleum resins, terpene resins, acrylic resins, and modified resins thereof. Further, the resin may be hydrogenated. These may be used alone or in combination of two or more.
As described later, in the rubber composition of the present invention, the "rubber component" is a component that contributes to crosslinking, and is generally a polymer having a weight average molecular weight (Mw) of 10,000 or more, which is extracted with acetone. In the present invention, even in the case of the above-mentioned resin (resin in a solid state at room temperature (25°C)), components that fall under the definition of "rubber component" are considered "rubber components". shall apply.

From the viewpoint of reactivity with the dihydric phenol compound, the resin is preferably a modified resin. Examples of the functional groups added to the modified resin include the aforementioned functional groups, and among them, from the viewpoint of reactivity with the dihydric phenol compound, fuel efficiency, wet grip performance, etc., carboxyl groups and amino groups are preferred. , epoxy groups are preferred.

The softening point of the resin is preferably 50°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher. The upper limit is preferably 160°C or less, more preferably 150°C or less, and even more preferably 145°C or less. Within the above range, tire performance such as wet grip performance tends to be better. The softening point of the resin is the temperature at which the softening point specified in JIS K6220-1:2001 is measured using a ring and ball softening point measuring device.

The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. Examples include resins obtained by polymerizing α-methylstyrene and/or styrene, specifically styrene homopolymers (styrene resins), α-methylstyrene homopolymers (α-methylstyrene resins), and α-methylstyrene homopolymers (α-methylstyrene resins). ), copolymers of α-methylstyrene and styrene, and copolymers of styrene and other monomers.

The above coumaron indene resin is a resin containing coumaron and indene as main monomer components constituting the skeleton (main chain) of the resin. In addition to coumaron and indene, monomer components contained in the skeleton include styrene, α-methylstyrene, methylindene, and vinyltoluene.

The above-mentioned coumaron resin is a resin containing coumaron as a main monomer component constituting the skeleton (main chain) of the resin.

The above-mentioned indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

As the above-mentioned phenol resin, known resins such as polymers obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst can be used. Among these, those obtained by reaction with an acid catalyst (such as novolac type phenol resin) are preferred.

Examples of the rosin resin include rosin resins typified by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

Examples of the petroleum resin include C5-based resins, C9-based resins, C5/C9-based resins, dicyclopentadiene (DCPD) resins, and hydrogenated products thereof. Among these, DCPD resin and hydrogenated DCPD resin are preferred.

The above-mentioned terpene resin is a polymer containing terpene as a constituent unit. Examples include polyterpene resins obtained by polymerizing terpene compounds, aromatic modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds, and the like. Aromatically modified terpene resins include terpene phenol resins made from terpene compounds and phenol compounds, terpene styrene resins made from terpene compounds and styrene compounds, and terpene styrene resins made from terpene compounds, phenol compounds, and styrene compounds. Terpenephenolstyrenic resins can also be used. Examples of terpene compounds include α-pinene and β-pinene; examples of phenolic compounds include phenol and bisphenol A; and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.).

The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, styrene acrylic resins such as styrene acrylic resins, which have a carboxyl group and are obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component, can be mentioned. Among these, solvent-free carboxyl group-containing styrene acrylic resins can be preferably used.

The reaction process between the dihydric phenol compound and the polymer is not particularly limited, and a known method can be used, and it may be carried out in a solvent such as water or an organic solvent, or it may be carried out without a solvent. . The solvent is not particularly limited, but it is preferably one in which both the dihydric phenol compound and the polymer can be easily dissolved. The solvent used in the reaction is not particularly limited, and any solvent that allows the reaction to proceed may be appropriately selected, such as ethers such as ethylene glycol dimethyl ether, tetrahydrofuran, and 1,4-dioxane, and aromatic hydrocarbons such as toluene. , dimethyl sulfoxide (DMSO), water, and mixtures thereof. Known catalysts can be used as appropriate for the reaction, such as palladium catalysts, EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide), HOBt (1-hydroxybenzotriazole), and the like. The mixing ratio of the dihydric phenol compound used in the reaction and the polymer may be appropriately selected within a range that allows the reaction to proceed. The reaction temperature and time may be appropriately set depending on the dihydric phenol compound and the polymer at which the reaction proceeds.

To explain a specific example of synthesis of a modified polymer, for example, modified polymer A can be synthesized by the synthetic route shown in FIG.

Specifically, for example, the catecholamine shown in FIG. 1 is dissolved in dimethyl sulfoxide (DMSO), and the resulting solution is added to a CHCl ₃ solution of liquid polyisoprene modified with carboxyl groups.
Next, catalysts (condensing agents) EDC, HOBt, and TEA are further added to the prepared solution and dissolved by stirring.
By reacting overnight, precipitating in methanol, and drying, the target modified polymer (polymer modified with a catechol compound represented by the above formula (1b) (modified polymer A)) is obtained.

As mentioned above, the rubber composition of the present invention contains a modified polymer modified with the above-mentioned dihydric phenol compound, and includes, for example, a modified polymer of rubber such as the above-mentioned diene rubber (modified rubber), the above-mentioned liquid Modified polymers of liquid polymers (modified liquid polymers) that are in a liquid state at room temperature (25°C), such as resins, and modified polymers (modified resins) of resins that are in a solid state at room temperature (25°C), such as the aromatic vinyl polymer mentioned above. Can be mentioned.
Among these, a composition containing at least one of the modified rubber and the modified liquid polymer is desirable.

The rubber composition includes a rubber component.
In the rubber composition of the present invention, the "rubber component" is a component that contributes to crosslinking, and is generally a polymer having a weight average molecular weight (Mw) of 10,000 or more and which is not extracted by acetone. Corresponds to rubber components.
Here, if the modified polymer modified with the dihydric phenol compound is crosslinked, has an Mw of 10,000 or more, and is not extracted by acetone, the modified polymer corresponds to a rubber component.

When the rubber composition includes a modified polymer modified with the dihydric phenol compound corresponding to the rubber component, the content of the modified polymer modified with the dihydric phenol compound in 100% by mass of the rubber component is particularly Although not limited, it is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The upper limit is not particularly limited, but is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.
In addition, "the content of the modified polymer modified with the dihydric phenol compound in 100% by mass of the rubber component" refers to the modified polymer modified with the dihydric phenol compound corresponding to the rubber component in 100% by mass of the rubber component. Refers to the polymer content.

When a rubber component includes a modified polymer modified with the dihydric phenol compound, the rubber composition may contain other "rubber components" other than the modified polymer modified with the dihydric phenol compound. Examples of other rubber components include the aforementioned diene rubber, butyl rubber, and fluororubber.

In this case, the content of the other rubber components in 100% by mass of the rubber component is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit is not particularly limited, but is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.

On the other hand, when the modified polymer modified with the dihydric phenol compound is a modified polymer that is in a liquid state at 25°C (modified liquid polymer), in the rubber composition, the modified polymer modified with the dihydric phenol compound based on 100 parts by mass of the rubber component is The content of the modified polymer (modified liquid polymer) is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 25 parts by mass or more, particularly preferably 30 parts by mass or more. The upper limit is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 40 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.
In this case, the modified polymer modified with the dihydric phenol compound (modified liquid polymer) corresponds to a liquid plasticizer (a plasticizer in a liquid state at normal temperature (25° C.)) described below.

Further, in the case where the modified polymer modified with the dihydric phenol compound is a modified polymer (modified resin) of a resin that is solid at 25°C, in the rubber composition, the modified polymer modified with the dihydric phenol compound based on 100 parts by mass of the rubber component. The content of the modified modified polymer (modified resin) is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 25 parts by mass or more, particularly preferably 30 parts by mass or more. The upper limit is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 40 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.
In this case, the modified polymer (modified resin) modified with the dihydric phenol compound corresponds to the resin described below (resin in a solid state at room temperature (25° C.)).

(filler)
The rubber composition of the present invention contains silica.
Examples of usable silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), and the like. Among these, wet process silica is preferred because it has a large number of silanol groups. As the silica, for example, products manufactured by Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used.

The average particle diameter of silica is preferably 24 nm or less, more preferably 17 nm or less, even more preferably 16 nm or less, particularly preferably 15 nm or less, and preferably 6 nm or more, more preferably 9 nm or more, and even more preferably 12 nm or more. It is. Within the above range, better effects tend to be obtained.

In this specification, transmission electron microscopy (TEM) observation is used to measure the average particle diameter of silica. Specifically, silica particles are photographed using a transmission electron microscope, and when the particle shape is spherical, the diameter of the sphere is taken as the particle diameter, and when it is acicular or rod-like, the short axis is taken as the particle diameter. In the case of a standard type, the average particle diameter from the center is defined as the particle diameter, and the average value of the particle diameters of 100 fine particles is defined as the average particle diameter.

In the rubber composition, the content of silica is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 75 parts by mass or more, particularly preferably 85 parts by mass, based on 100 parts by mass of the rubber component. That's all. The upper limit is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.

Although it is not necessarily clear why the above effects are better obtained when the predetermined amount of silica is included, it is presumed to be due to the following mechanism.
It is thought that the dihydric phenol compound interacts with the silica, disperses the silica well, and improves the wet grip performance. Therefore, it is presumed that the overall performance of fuel efficiency and wet grip performance is further improved.

When containing silica, a silane coupling agent may be blended with the silica.
The usable silane coupling agent is not particularly limited and can be any silane coupling agent conventionally used in combination with silica in the rubber industry. For example, bis(3-triethoxysilylpropyl)tetra Sulfide, 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-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N - Sulfide series such as dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercapto Ethyltriethoxysilane, mercapto type such as NXT and NXT-Z manufactured by Momentive, vinyl type such as vinyltriethoxysilane and vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, etc. Amino type, glycidoxy type such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3- Examples include chloro-based materials such as chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. As commercially available products, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Kasei Kogyo Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among these, sulfide type and mercapto type are preferred, and mercapto type is more preferred.

As the mercapto-based silane coupling agent, in addition to compounds having a mercapto group, compounds having a structure in which a mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used.

（式中、Ｒ^１００１は－Ｃｌ、－Ｂｒ、－ＯＲ^１００６、－Ｏ（Ｏ＝）ＣＲ^１００６、－ＯＮ＝ＣＲ^１００６Ｒ^１００７、－ＮＲ^１００６Ｒ^１００７及び－（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１～１８の一価の炭化水素基であり、ｈは平均値が１～４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１～１８の一価の炭化水素基、Ｒ^１００３は－［Ｏ（Ｒ^１００９Ｏ）_ｊ］－基（Ｒ^１００９は炭素数１～１８のアルキレン基、ｊは１～４の整数である。）、Ｒ^１００４は炭素数１～１８の二価の炭化水素基、Ｒ^１００５は炭素数１～１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。）

（式中、ｖは０以上の整数、ｗは１以上の整数である。Ｒ^１１は水素、ハロゲン、分岐若しくは非分岐の炭素数１～３０のアルキル基、分岐若しくは非分岐の炭素数２～３０のアルケニル基、分岐若しくは非分岐の炭素数２～３０のアルキニル基、又は該アルキル基の末端の水素が水酸基若しくはカルボキシル基で置換されたものを示す。Ｒ^１２は分岐若しくは非分岐の炭素数１～３０のアルキレン基、分岐若しくは非分岐の炭素数２～３０のアルケニレン基、又は分岐若しくは非分岐の炭素数２～３０のアルキニレン基を示す。Ｒ^１１とＲ^１２とで環構造を形成してもよい。） Particularly suitable mercapto-based silane coupling agents include a silane coupling agent represented by the following formula (S1), and a combination of a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II). Examples include silane coupling agents containing silane coupling agents.

(In the formula, R ¹⁰⁰¹ is -Cl, -Br, -OR ¹⁰⁰⁶ , -O(O=)CR ¹⁰⁰⁶ , -ON=CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , -NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and -(OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) (R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ may be the same or different, each being a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms; , h has an average value of 1 to 4), R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is -[O(R ¹⁰⁰⁹ O) _j ]- group (R ¹⁰⁰⁹ is an alkylene group having 1 to 18 carbon atoms, j is an integer of 1 to 4), R ¹⁰⁰⁴ is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 1005 is an alkylene group having 1 to 18 carbon atoms, and R ¹⁰⁰⁵ is a divalent hydrocarbon group having 1 to 18 carbon atoms. ~18 monovalent hydrocarbon groups, x, y, and z are numbers that satisfy the following relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1.)

⁽ In the formula, v is an integer of 0 or more, and w is an integer of 1 or more. 30 alkenyl group, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or one in which the terminal hydrogen of the alkyl group is substituted with a hydroxyl group or carboxyl group.R ¹² is the branched or unbranched carbon number It represents an alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms.R ¹¹ and R ¹² form a ring structure. )

In formula (S1), R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ each independently represent a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aryl group and an aralkyl group. Preferably, it is a group selected from the group consisting of: Further, when R ¹⁰⁰² is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is selected from the group consisting of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group. It is preferable that it is a group. R ¹⁰⁰⁹ is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. R ¹⁰⁰⁴ is, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, or an arylene group having 6 to 18 carbon atoms. and an aralkylene group having 7 to 18 carbon atoms. Alkylene groups and alkenylene groups may be linear or branched, and cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups have a functional group such as a lower alkyl group on the ring. You may do so. R ¹⁰⁰⁴ is preferably an alkylene group having 1 to 6 carbon atoms, particularly a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, or a hexamethylene group.

Specific examples of R ¹⁰⁰² , R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ in formula (S1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group. group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclo Examples include hexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, and naphthylmethyl group.
As an example of R ¹⁰⁰⁹ in formula (S1), linear alkylene groups include methylene group, ethylene group, n-propylene group, n-butylene group, hexylene group, etc., and branched alkylene groups include: Examples include isopropylene group, isobutylene group, and 2-methylpropylene group.

Specific examples of the silane coupling agent represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, and 3-hexanoylthiopropyltriethoxysilane. lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoyl ruthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthio Examples include ethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. These may be used alone or in combination of two or more. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

In the silane coupling agent containing bonding unit A represented by formula (I) and bonding unit B represented by formula (II), the content of bonding unit A is preferably 30 mol% or more, more preferably 50 mol%. % or more, preferably 99 mol% or less, more preferably 90 mol% or less. Further, the content of bonding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, More preferably, it is 55 mol% or less. Further, the total content of bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, particularly preferably 100 mol%.
Note that the content of the bonding units A and B includes the case where the bonding units A and B are located at the ends of the silane coupling agent. When the bonding units A and B are located at the ends of the silane coupling agent, the form is not particularly limited, as long as they form units corresponding to the formulas (I) and (II) representing the bonding units A and B. .

Regarding R ¹¹ in formulas (I) and (II), examples of halogen include chlorine, bromine, and fluorine. Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms include a methyl group and an ethyl group. Examples of branched or unbranched alkenyl groups having 2 to 30 carbon atoms include vinyl groups and 1-propenyl groups. Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms include ethynyl group and propynyl group.

For R ¹² in formulas (I) and (II), examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include ethylene group and propylene group. Examples of branched or unbranched alkenylene groups having 2 to 30 carbon atoms include vinylene groups and 1-propenylene groups. Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include ethynylene group and propynylene group.

In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the number of repeats (v) of bonding unit A and the number of repeats (w) of bonding unit B are The total number of repetitions (v+w) is preferably in the range of 3 to 300.

In the rubber composition, the content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, based on 100 parts by mass of silica. Moreover, the said content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less.

The rubber composition may also contain fillers other than silica.
Other fillers that can be used include those known in the rubber field, such as inorganic fillers such as carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica; and poorly dispersible fillers. From the viewpoint of tire performance when applied to tire members, carbon black is preferred.

Carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, and the like. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or may be obtained by recycling tires. Further, the method for producing carbon black may be by combustion such as a furnace method, or by hydrothermal carbonization (HTC). Commercially available products include Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Nippon Kayaku Carbon Co., Ltd., and Columbia Carbon Co., Ltd. can. These may be used alone or in combination of two or more.

The cetyltrimethylammonium bromide (CTAB) specific surface area of carbon black is preferably 110 m ² /g or more, more preferably 120 m ² /g or more, even more preferably 130 m ² /g or more, and preferably 200 m ² /g. It is more preferably 160 m ² /g or less, still more preferably 140 m ² /g or less. Within the above range, better effects tend to be obtained.
Note that the CTAB specific surface area of carbon black is a value measured in accordance with JIS K6217-3:2001.

In the rubber composition, the content of carbon black is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 45 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.

In the rubber composition, the total amount of filler is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 85 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 200 parts by weight or less, more preferably 150 parts by weight or less, still more preferably 105 parts by weight or less, particularly preferably 95 parts by weight or less. Within the above range, there is a tendency for favorable effects to be obtained.

(Plasticizer)
The rubber composition may include a plasticizer.
A plasticizer is a material that imparts plasticity to a rubber component, such as liquid plasticizer (a plasticizer that is in a liquid state at room temperature (25°C)), resin (a resin that is in a solid state at room temperature (25°C)), etc. Can be mentioned.

In the rubber composition, the content of the plasticizer (total content of the modified polymer modified with the dihydric phenol compound (modified liquid polymer, modified resin) and other plasticizers) is based on 100 parts by mass of the rubber component. , preferably 15 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 40 parts by mass or more, particularly preferably 45 parts by mass or more. The upper limit is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 60 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.

Liquid plasticizers (plasticizers in a liquid state at room temperature (25°C)) that can be used in the rubber composition are not particularly limited, and may include oils, liquid polymers (the aforementioned liquid resins, liquid diene polymers, liquid farnesene polymers, etc.). ), etc. Here, examples of the liquid polymer include, in addition to the above-mentioned liquid resin, liquid diene polymer, and liquid farnesene polymer, a modified polymer that is in a liquid state at 25° C. (modified liquid polymer) that has been modified with the dihydric phenol compound. . These liquid plasticizers may be used alone or in combination of two or more.

In the rubber composition, the content of the liquid plasticizer is preferably 15 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, particularly preferably 45 parts by mass, based on 100 parts by mass of the rubber component. It is more than 100%. The upper limit is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 60 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.
Note that the content of liquid plasticizer also includes the amount of oil contained in the oil-extended rubber.

Oils include, for example, process oils, vegetable oils, or mixtures thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, and olive oil. , sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. Commercially available products include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo 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. Products from Nisshin Oilio Group Co., Ltd., etc. can be used. Among these, process oils (paraffinic process oils, aromatic process oils, naphthenic process oils, etc.) and vegetable oils are preferred.

In the rubber composition, the oil content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, still more preferably 30 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.
Note that the oil content also includes the amount of oil contained in the oil-extended rubber.

Examples of the above-mentioned resins (resins in a solid state at room temperature (25°C)) that can be used in the rubber composition include the above-mentioned aromatic vinyl polymers that are in a solid state at room temperature (25°C), coumaron indene resin, and coumaron resin. , indene resin, phenol resin, rosin resin, petroleum resin, terpene resin, acrylic resin, etc. In addition, the above-mentioned resins include the above-mentioned aromatic vinyl polymer that is solid at room temperature (25°C), coumaron indene resin, coumaron resin, indene resin, phenol resin, rosin resin, petroleum resin, terpene resin, acrylic resin. In addition to resins, modified polymers modified with the dihydric phenol compound and solid at 25° C. can also be used. The above resin may be hydrogenated. These resins may be used alone or in combination of two or more. Among these, aromatic vinyl polymers, petroleum resins, and terpene resins are preferred.

In the rubber composition, the content of the resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 7 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 90 parts by mass or less. Within the above range, there is a tendency for favorable effects to be obtained.

Examples of plasticizers include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., Nichino Chemical Co., Ltd. Products from Nippon Shokubai, ENEOS Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

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

The anti-aging agent is not particularly limited, but includes naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-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 type anti-aging agents such as diamines; quinoline type anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methyl Monophenolic anti-aging agents such as phenol and styrenated phenol; bis, tris, and polyphenols such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane; Examples include anti-aging agents. Among these, p-phenylenediamine-based antiaging agents and quinoline-based antiaging agents are preferred, including N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 , 2-dihydroquinoline polymers are more preferred. As commercially available products, for example, products manufactured by Seiko Kagaku Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis Co., Ltd., etc. can be used.

In the rubber composition, the content of the antiaging agent is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less.

The rubber composition may include stearic acid. In the rubber composition, 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, based on 100 parts by mass of the rubber component.

As the stearic acid, conventionally known ones can be used, and for example, products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

The rubber composition may include zinc oxide. In the rubber composition, the content of zinc oxide is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the rubber component.

As the zinc oxide, conventionally known zinc oxides can be used, such as those manufactured by Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. products can be used.

The rubber composition may contain wax. In the rubber composition, the wax content is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the rubber component.

The wax is not particularly limited, and includes petroleum waxes, natural waxes, etc. Synthetic waxes obtained by refining or chemically processing multiple 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 waxes derived from resources other than petroleum; for example, vegetable waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and jojoba wax; beeswax, lanolin, spermaceti wax, etc. animal waxes; mineral waxes such as ozokerite, ceresin, and petrolactam; and purified products thereof. As commercially available products, for example, products manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used.

The rubber composition may contain sulfur.
In the rubber composition, the content of sulfur is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 0.7 parts by mass or more, based on 100 parts by mass of the rubber component. be. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, still more preferably 3.0 parts by mass or less.

Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc. commonly used in the rubber industry. As commercially available products, products manufactured by Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis, Nippon Kanditsu 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 may also include a vulcanization accelerator.
In the rubber composition, the content of the vulcanization accelerator is usually 0.3 to 10 parts by weight, preferably 0.5 to 7 parts by weight, based on 100 parts by weight of the rubber component.

The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of vulcanization accelerators include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; tetramethylthiuram disulfide (TMTD); ), thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- Sulfenamide vulcanization accelerators such as 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide; diphenylguanidine; Examples include guanidine-based vulcanization accelerators such as di-ortho-tolyl guanidine and ortho-tolyl biguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

In addition to the above-mentioned components, the rubber composition may also contain appropriate additives such as release agents and pigments, depending on the field of application.

As a method for producing the rubber composition, a known method can be used. For example, it can be produced by kneading each component using a rubber kneading device such as an open roll or a Banbury mixer, and crosslinking as necessary. As for the kneading conditions, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes.

The rubber composition can be used for tires, shoe soles, flooring materials, vibration-proofing materials, seismic isolation materials, butyl frame materials, belts, hoses, packings, medicine stoppers, and other rubber industrial products. In particular, it is preferable to use it as a rubber composition for tires because it has excellent tire performance such as wet grip performance.

Tire members to which the rubber composition is applied are not particularly limited, and include treads (cap tread, base tread, etc.), sidewalls, bead apex, clinch apex, inner liner, undertread, breaker topping, ply topping, etc. Each member of an arbitrary tire may be mentioned. Among these, it can be suitably applied to treads because it has excellent wet grip performance.

<Tires>
Examples of tires to which the rubber composition is applied include pneumatic tires and non-pneumatic tires, among which pneumatic tires are preferred. In particular, it can be suitably used as summer tires, winter tires (studless tires, snow tires, studded tires, etc.), all-season tires, and the like. The tires can be used as tires for passenger cars, tires for large passenger cars, tires for large SUVs, tires for heavy loads such as trucks and buses, tires for light trucks, tires for two-wheeled vehicles, tires for racing (high performance tires), and the like. Among them, it can be suitably used for tires for passenger cars and tires for light trucks.

A tire is manufactured using the rubber composition according to a conventional method. For example, a rubber composition blended with various materials is extruded to match the shape of a tire component such as a tread at an unvulcanized stage, and then molded along with other tire components using a normal method on a tire molding machine. By this, after forming an unvulcanized tire, it can be heated and pressurized in a vulcanizer to manufacture a tire.

Examples (Examples) that are considered preferable for implementation are shown below, but the scope of the present invention is not limited to the Examples.

<Synthesis of modified polymer modified with dihydric phenol compound>
Modified polymer A (polymer modified with a catechol compound represented by formula (1b)) is synthesized by the synthetic route shown in FIG. 1.
Specifically, it is synthesized by the following method.

(Synthesis of modified polymer A)
Catecholamines are dissolved in dimethyl sulfoxide (DMSO) and the resulting solution is added to a solution of liquid polyisoprene modified with carboxyl groups in _CHCl3 .
Next, catalysts (condensing agents) EDC, HOBt, and TEA are further added to the prepared solution and dissolved by stirring.
By reacting overnight, precipitating in methanol, and drying, modified polymer A (component contributing to crosslinking, Mw approximately 30,000, polymer not extracted by acetone) is obtained.

In addition, the following materials are used for the synthesis of modified polymer A shown in FIG.
Catecholamine: manufactured by TCI DMSO: dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Liquid polyisoprene modified with carboxyl groups (LIR-410 manufactured by Kuraray, molecular weight 30,000, number of carboxyl groups per molecule: 10, glass transition temperature -59°C)
EDC: 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (manufactured by TCI)
HOBt: 1-hydroxybenzotriazole (manufactured by TCI)
TEA: Triethylamine (manufactured by TCI)

Note that it can be analyzed from the IR spectrum and ¹ H-NMR spectrum that liquid polyisoprene (modified polymer A) modified with catecholamine (catechol compound represented by formula (1)) is synthesized.

As described above, it is considered possible to synthesize a polymer modified with the dihydric phenol compound.

Below, various chemicals used in Examples and Comparative Examples will be explained.

(rubber component)
NR:TSR20
SBR: HPR850 manufactured by JSR Corporation (styrene content: 27.5% by mass, vinyl bond amount: 59.0% by mass)
BR: BR150B manufactured by Ube Industries, Ltd. (vinyl content: 1% by mass, cis content: 97% by mass)
Modified polymer A: Synthesis of the above modified polymer A

(Chemicals other than rubber components)
Silica 1: Ultrasil VN3 manufactured by Evonik Degussa (average particle size: 17 nm)
Silica 2: Ultrasil 9100GR manufactured by Evonik Degussa (average particle size: 15 nm)
Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa
Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive
Carbon black 1: N220 (CTAB specific surface area: 111 m ² /g)
Carbon black 2: N134 (CTAB specific surface area: 142 m ² /g)
Solid resin: Sylvatraxx4401 manufactured by Arizona Chemical Company (styrene α-methylstyrene resin (copolymer of styrene and α-methylstyrene))
Oil: H&R VIVATEC500 (aromatic process oil)
Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Anti-aging agent: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p- manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) phenylenediamine)
Stearic acid: stearic acid “Tsubaki” manufactured by NOF Corporation
Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. 1: Noxela D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Noxela NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

<Preparation of test tires>
According to the formulation shown in Table 1, chemicals other than sulfur and the vulcanization accelerator are kneaded using a 1.7L Banbury mixer.
Next, sulfur and a vulcanization accelerator are added and kneaded into the obtained kneaded product using a roll to obtain an unvulcanized rubber composition.
The resulting unvulcanized rubber composition was molded into a tread shape and bonded together with other tire members on a tire molding machine to form an unvulcanized tire, which was then vulcanized at 170°C for 12 minutes and used for testing. Manufacture tires (size: 195/65R15, specifications: each table).

Table 1 shows the results calculated based on the following evaluation method assuming a test tire obtained from a composition whose formulation was changed according to Table 1.
Note that the standard comparative example is as follows.
Table 1: Comparative example 1

<Wet grip performance>
Each test tire is attached to all wheels of a vehicle (domestic FF 2000cc), and the braking distance from an initial speed of 100 km/h on a wet asphalt road surface is determined and expressed as an index when the standard comparative example is set as 100 (wet grip performance index). The larger the index, the shorter the braking distance and the better the wet grip performance.

<Fuel efficiency>
Each test tire was attached to all wheels of a vehicle (domestic FF 2000cc), and the distance from an initial speed of 100 km/h on a dry road surface until the vehicle came to a standstill when the accelerator was turned off was determined, and the standard comparison example Displayed as an index when the value is set to 100 (low fuel consumption performance index). The larger the index, the longer the distance until the vehicle comes to a standstill, and the better the fuel efficiency.

The present invention (1) is a rubber composition containing a modified polymer modified with a dihydric phenol compound and silica.

The present invention (2) is the rubber composition according to the present invention (1), wherein the modified polymer is a rubber component.

The present invention (3) is the rubber composition according to the present invention (1), wherein the modified polymer is a modified polymer that is in a liquid state at 25°C.

The present invention (4) is any one of the present inventions (1) to (3), wherein the dihydric phenol compound contains at least one selected from the group consisting of dobamine, noradrenaline, adrenaline, dihydroxyphenylacetic acid, and dihydroxyhydrocinnamic acid. A rubber composition according to claim 1.

The present invention (5) is characterized in that the polymer constituting the skeleton of the modified polymer is at least one selected from the group consisting of isoprene rubber, acrylonitrile butadiene rubber, butadiene rubber, and styrene butadiene rubber. The rubber composition according to any one of 4).

The present invention (6) is the rubber composition according to any one of the present inventions (1) to (5), wherein the content of silica is 10 to 150 parts by mass based on 100 parts by mass of the rubber component.

The present invention (7) is the rubber composition according to any one of the present inventions (1) to (6), wherein the average particle diameter of the silica is 16 nm or less.

The present invention (8) is the rubber composition according to any one of the present inventions (1) to (7), which contains a mercapto-based silane coupling agent.

The present invention (9) is the rubber composition according to any one of the present inventions (1) to (8), which contains a resin.

The present invention (10) is the rubber composition according to the present invention (9), wherein the resin is an aromatic resin.

The present invention (11) is the rubber composition according to any one of the present inventions (1) to (10), which contains carbon black having a cetyltrimethylammonium bromide specific surface area of 130 m ² /g or more.

The present invention (12) is a tire having a tire member made of the rubber composition according to any one of the present inventions (1) to (11).

Claims (12)

A rubber composition containing a modified polymer modified with a dihydric phenol compound and silica. The rubber composition according to claim 1, wherein the modified polymer is a rubber component. The rubber composition according to claim 1, wherein the modified polymer is a modified polymer that is in a liquid state at 25°C. The rubber composition according to any one of claims 1 to 3, wherein the dihydric phenol compound contains at least one selected from the group consisting of dobamine, noradrenaline, adrenaline, dihydroxyphenylacetic acid, and dihydroxyhydrocinnamic acid. 2. The rubber composition according to claim 1, wherein the polymer constituting the skeleton of the modified polymer is at least one selected from the group consisting of isoprene rubber, acrylonitrile butadiene rubber, butadiene rubber, and styrene butadiene rubber. The rubber composition according to claim 1, wherein the content of silica is 10 to 150 parts by mass based on 100 parts by mass of the rubber component. The rubber composition according to claim 1, wherein the silica has an average particle diameter of 16 nm or less. The rubber composition according to claim 1, comprising a mercapto silane coupling agent. The rubber composition according to claim 1, comprising a resin. The rubber composition according to claim 9, wherein the resin is an aromatic resin. The rubber composition according to claim 1, comprising carbon black having a cetyltrimethylammonium bromide specific surface area of 130 m ² /g or more. A tire comprising a tire member made of the rubber composition according to claim 1.

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