JP2014198821A - Tire rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire rubber composition which, while having excellent processability, can improve fuel economy, wet grip performance, wear resistance and driving stability in a balanced manner, and a pneumatic tire with the rubber composition used as a tread.SOLUTION: A tire rubber composition comprises: rubber components; silica; a silane coupling agent comprising a mercapto group which comprises a polysilyl bond unit (A) with a thiocarbonyl group and a polysilyl bond unit (B) with thiol, wherein the content of the bond unit (B) is 1-70 mol%; and saccharides.

Description

The present invention relates to a tire rubber composition and a pneumatic tire in which the rubber composition is applied to a tread.

In general, as a method of improving both the rolling resistance and wet grip performance (grip property on wet road surface or braking distance) of a pneumatic tire, silica filler is used and a rubber composition having a high glass transition temperature is used at a low temperature. Although there is a known method for increasing the hysteresis loss in the rubber composition, although the wet grip performance is improved with the rubber composition, the hysteresis loss at high temperature also increases, the rolling resistance increases, and the wear resistance performance also decreases. Tend. In addition, silica is agglomerated during kneading to increase the viscosity, resulting in a problem that the kneaded dough deteriorates and the workability is lowered.

A method using a copolymer such as styrene-isoprene-butadiene copolymer rubber (SIBR) has also been proposed, but it is difficult to achieve both high levels of wet grip performance and rolling resistance. Even if the low heat build-up is improved, there is a problem that steering stability and wet grip performance are lowered due to softening of rubber.

Furthermore, it is also proposed to add various silane coupling agents in order to enhance the reinforcing effect of the silica-containing rubber. Patent Document 1 and the like include sulfide-based silane cups such as bis- (3-triethoxysilylpropyl) tetrasulfide. Although the ring agent is disclosed, there are problems such as an increase in viscosity during processing of the rubber composition. Moreover, although the mercapto-type silane coupling agent is also disclosed, there are problems such as deterioration of the smoothness of the kneaded dough during processing.

Thus, in the silica compounded system, it is difficult to improve the fuel efficiency, wet grip performance, wear resistance and steering stability of the rubber composition produced in a well-balanced manner while being excellent in processability during production. Improvements are desired.

JP 2002-363346 A

The present invention solves the above-mentioned problems and has a rubber composition for tires that can improve fuel economy, wet grip performance, wear resistance, and steering stability in a well-balanced manner while having good processability, and the rubber composition An object of the present invention is to provide a pneumatic tire using a tire as a tread.

（式中、Ｒ^１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^２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^１とＲ^２とで環構造を形成してもよい。） The present invention includes a rubber component, silica, a binding unit A represented by the following general formula (1) and a binding unit B represented by the following general formula (2), and the content of the binding unit B is 1 to 70. The present invention relates to a rubber composition for tires containing a silane coupling agent having a mercapto group of mol% and a saccharide.

Wherein R ¹ is hydrogen, halogen, branched or unbranched alkyl group having 1 to 30 carbon atoms, branched or unbranched alkenyl group having 2 to 30 carbon atoms, branched or unbranched carbon group having 2 to 30 carbon atoms. An alkynyl group, or a group in which the terminal hydrogen of the alkyl group is substituted with a hydroxyl group or a carboxyl group, R ² represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched carbon number of 2 30 represents an alkenylene group or a branched or unbranched alkynylene group having 2 to 30 carbon atoms, and R ¹ and R ² may form a ring structure.)

The saccharide is preferably at least one selected from the group consisting of monosaccharides, disaccharides, trisaccharides, tetrasaccharides, oligosaccharides, and derivatives thereof.

The saccharide is preferably a polysaccharide and / or a derivative thereof.

It is preferable that the content of the silica is 15 to 150 parts by mass and the content of the saccharide is 2 to 25 parts by mass with respect to 100 parts by mass of the rubber component.

The silica is silica (I) having a nitrogen adsorption specific surface area of 100 m ² / g or less and silica (II) having a nitrogen adsorption specific surface area of 180 m ² / g or more, and the silica with respect to 100 parts by mass of the rubber component The total content of (I) and (II) is preferably 10 to 150 parts by mass, and the content of silica (I) and (II) preferably satisfies the following formula.
(Content of silica (I)) × 0.2 ≦ (content of silica (II)) ≦ (content of silica (I)) × 6.5

In 100% by mass of the rubber component, the content of styrene butadiene rubber is preferably 30% by mass or more.

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

According to the present invention, since it is a rubber composition for a tire containing a rubber component, silica, a specific mercapto-based silane coupling agent, and a saccharide, excellent processability at the time of processing (production) of the rubber composition It is possible to provide a pneumatic tire with improved fuel economy, wet grip performance, wear resistance, and steering stability in a well-balanced manner.

The rubber composition for tires of the present invention contains a rubber component, silica, a silane coupling agent having a specific mercapto group, and a saccharide.

By adding both a specific mercapto-based silane coupling agent and a saccharide component in silica compounded rubber, while maintaining excellent processability during processing (manufacturing), low fuel consumption of the rubber composition produced It is possible to synergistically improve the performance balance of (rolling resistance), wet grip performance, wear resistance, and steering stability, particularly low fuel consumption, wet grip performance, and wear resistance. The reason why such an effect is obtained is not clear, but it is presumed that the use of a specific mercapto-based silane coupling agent together with saccharide synergistically improves the dispersibility of silica.

The rubber component is not particularly limited. For example, natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), isoprene rubber (IR), ethylene propylene diene rubber ( EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. Of these, SBR and BR are preferable, and SBR is particularly preferable from the viewpoint of improving wet grip performance, rolling resistance, and wear resistance.

SBR is not particularly limited, and those commonly used in the tire industry such as emulsion-polymerized styrene butadiene rubber (E-SBR), solution-polymerized styrene butadiene rubber (S-SBR), and modified SBR thereof can be used. Among them, from the viewpoint of improving wet grip performance, rolling resistance and abrasion resistance, it is modified (coupled) with a polyfunctional compound (modifier) having two or more epoxy groups in the molecule, and hydroxyl groups and epoxies. Modified SBR into which a group has been introduced is preferred. In addition, what made the modifier react with the terminal of rubber | gum is preferable, and the modification | denaturation method can be implemented by a conventionally well-known method, such as the method of adding a modifier to SBR solution and making it react.

The polyfunctional compound having two or more epoxy groups in the molecule is not particularly limited as long as it is a compound having two or more epoxy groups in the molecule, but two or more epoxy groups and one or more in the molecule. A polyfunctional compound having a nitrogen-containing group is preferred, and a polyfunctional compound represented by the following formula is more preferred.

（式中、Ｒ^１１及びＲ^１２は、同一又は異なって、炭素数１〜１０の２価の炭化水素基を表し、該炭化水素基は、エーテル、及び３級アミンからなる群より選択される少なくとも１種の基を有してもよい。Ｒ^１３及びＲ^１４は、同一若しくは異なって、水素原子、又は炭素数１〜２０の１価の炭化水素基を表し、該炭化水素基は、エーテル、及び３級アミンからなる群より選択される少なくとも１種の基を有してもよい。Ｒ^１５は、炭素数１〜２０の１〜６価の炭化水素基を表し、該炭化水素基は、エーテル、３級アミン、エポキシ、カルボニル、及びハロゲンからなる群より選択される少なくとも１種の基を有してもよい。ｍは１〜６（好ましくは１〜４）の整数を表す。）

(Wherein R ¹¹ and R ¹² are the same or different and represent a divalent hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group is selected from the group consisting of ethers and tertiary amines. R ¹³ and R ¹⁴ may be the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group is an ether And at least one group selected from the group consisting of tertiary amines, R ¹⁵ represents a 1 to 6-valent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group is And at least one group selected from the group consisting of ether, tertiary amine, epoxy, carbonyl, and halogen, m represents an integer of 1 to 6 (preferably 1 to 4).

The polyfunctional compound is more preferably a polyfunctional compound having a diglycidylamino group. Further, the number of epoxy groups in the molecule of the polyfunctional compound is 2 or more, more preferably 3 or more, and further preferably 4 or more.

The content of SBR in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 50% by mass or more, and still more preferably 70 from the viewpoint that wet grip performance, rolling resistance and wear resistance can be improved. It may be 100% by mass or more.

The BR is not particularly limited. For example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR150B manufactured by Ube Industries, Ltd., high cis content BR, 1, VCR412, VCR617 manufactured by Ube Industries, etc. Commonly used in the tire industry such as BR containing 2-syndiotactic polybutadiene crystal (SPB) can be used. Among these, BR having a cis content of 95% by mass or more is preferable.

The content of BR in 100% by mass of the rubber component is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, and may not be blended. If it exceeds 40% by mass, the performance balance of wet grip performance, rolling resistance and wear resistance may be lowered.

Examples of the silica include, but are not limited to, dry method silica (anhydrous silicic acid), wet method silica (anhydrous silicic acid), and the like, and wet method silica is preferable because it has many silanol groups. Examples of commercially available wet process silica include Ultrasil VN3 manufactured by Degussa, and Nip Seal VN3 AQ manufactured by Nippon Silica Kogyo Co., Ltd. Silica may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of the silica is preferably 20 m ² / g or more, more preferably 50 m ² / g or more, still more preferably 100 m ² / g or more, and particularly preferably 150 m ² / g or more. . Further, it is preferably 400 m ² / g or less, more preferably 300 m ² / g or less, still more preferably 250 m ² / g or less. If it is less than 20 m ² / g, the dispersibility improving effect and the reinforcing effect tend to be small, and if it exceeds 400 m ² / g, the dispersibility is poor and the heat generation property of the tire tends to increase.

The content of silica is preferably 15 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, Preferably it is 150 mass parts or less, More preferably, it is 120 mass parts or less, More preferably, it is 100 mass parts or less. If it is less than 15 parts by mass, the effect of blending, that is, wet grip performance and rolling resistance cannot be improved, and if it exceeds 150 parts by mass, the dispersibility of silica is deteriorated and the properties such as wear resistance and strength are deteriorated. Tend.

When two or more types of silica are blended, silica (I) having a nitrogen adsorption specific surface area of 100 m ² / g or less and silica (II) having a nitrogen adsorption specific surface area of 180 m ² / g or more in a predetermined ratio. It is preferable to mix. By blending the silica (I) and (II) at a predetermined ratio, wet grip performance and wear resistance can be further improved.

The N ₂ SA of silica (I) is preferably 100 m ² / g or less, more preferably 80 m ² / g or less, and still more preferably 60 m ² / g or less. When it exceeds 100 m < ² > / g, there exists a possibility that the effect by combined use of silica (I) and (II) may not fully be acquired. N ₂ SA of silica (I) is preferably 20 m ² / g or more, more preferably 30 m ² / g or more. If it is less than 20 m ² / g, sufficient reinforcing properties cannot be obtained, and the wear resistance tends to deteriorate.

Although it does not specifically limit as silica (I), For example, Ultrasil 360 by Degussa, Z40 by Rhodia, RP80 by Rhodia, etc. can be used. Silica (I) may be used alone or in combination of two or more.

The content of silica (I) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 1 part by mass, the rolling resistance tends not to be sufficiently reduced. The content of silica (I) 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, and particularly preferably 50 parts by mass or less. When it exceeds 150 mass parts, there exists a tendency for abrasion resistance to deteriorate.

N ₂ SA of silica (II) is preferably 180 m ² / g or more, more preferably 190 m ² / g or more, and further preferably 200 m ² / g or more. If it is less than 180 m ² / g, the effect of the combined use of silica (I) and (II) may not be sufficiently obtained. Further, N ₂ SA of silica (II) is preferably 300 m ² / g or less, more preferably 240 m ² / g or less. If it exceeds 300 m ² / g, the fuel efficiency tends to deteriorate.

Although it does not specifically limit as silica (II), For example, Zeosyl 1205MP made from Rhodia etc. can be used. Silica (II) may be used alone or in combination of two or more.

The content of silica (II) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 1 part by mass, there is a tendency that sufficient wear resistance cannot be obtained. The content of silica (II) 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, and particularly preferably 60 parts by mass or less. If it exceeds 150 parts by mass, the fuel efficiency tends to deteriorate.

The total content of silica (I) and (II) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 mass parts, there exists a tendency for sufficient reinforcement effect by blending silica (I) and (II) not to be acquired. The total content of silica (I) and (II) is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 100 parts by mass or less. When the amount exceeds 150 parts by mass, it is difficult to uniformly disperse silica in the rubber composition, and the fuel efficiency tends to deteriorate.

The content of silica (I) and the content of (II) preferably satisfy the following formula.
(Content of silica (I)) × 0.2 ≦ (content of silica (II)) ≦ (content of silica (I)) × 6.5
The content of silica (II) is preferably 0.2 times or more, more preferably 0.5 times or more of the content of silica (I). If it is less than 0.2 times, sufficient reinforcing properties may not be obtained. Further, the content of silica (II) is preferably 6.5 times or less, more preferably 4 times or less, and still more preferably 1 time (1 time) or less of the content of silica (I). If it exceeds 6.5 times, a sufficient improvement effect may not be obtained.
In addition, content of silica (I) and silica (II) is a mass part with respect to 100 mass parts of rubber components.

（式中、Ｒ^１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^２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^１とＲ^２とで環構造を形成してもよい。） In the present invention, the specific mercapto-based silane coupling agent includes a bonding unit A represented by the following general formula (1) and a bonding unit B represented by the following general formula (2), and the inclusion of the bonding unit B A silane coupling agent having a mercapto group in an amount of 1 to 70 mol% is used.

Wherein R ¹ is hydrogen, halogen, branched or unbranched alkyl group having 1 to 30 carbon atoms, branched or unbranched alkenyl group having 2 to 30 carbon atoms, branched or unbranched carbon group having 2 to 30 carbon atoms. An alkynyl group, or a group in which the terminal hydrogen of the alkyl group is substituted with a hydroxyl group or a carboxyl group, R ² represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched carbon number of 2 30 represents an alkenylene group or a branched or unbranched alkynylene group having 2 to 30 carbon atoms, and R ¹ and R ² may form a ring structure.)

The silane coupling agent having the above structure has an increased viscosity during processing as compared with polysulfide silanes such as bis- (3-triethoxysilylpropyl) tetrasulfide because the molar ratio of the bond unit A to the bond unit B satisfies the above conditions. Is suppressed. This is presumably because the increase in Mooney viscosity is small because the sulfide portion of the bond unit A is a C—S—C bond and is thermally stable compared to tetrasulfide and disulfide.

Moreover, when the molar ratio of the bond unit A and the bond unit B satisfies the above conditions, shortening of the scorch time is suppressed as compared with mercaptosilane such as 3-mercaptopropyltrimethoxysilane. This is because the bonding unit B has a structure of mercaptosilane, but the —C ₇ H ₁₅ part of the bonding unit A covers the —SH group of the bonding unit B, so that it does not easily react with the polymer and scorch is less likely to occur. This is probably because of this.

In the silane coupling agent having the above structure, the content of the binding unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99, in that the effects of the present invention can be obtained satisfactorily. The mol% or less, more preferably 90 mol% or less. Further, the content of the bonding unit B is preferably 5 mol% or more, more preferably 10 mol% or more, preferably 65 mol% or less, more preferably 55 mol% or less. Further, the total content of the binding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%.
The content of the bond units A and B is an amount including the case where the bond units A and B are located at the terminal of the silane coupling agent. The form in which the bonding units A and B are located at the end of the silane coupling agent is not particularly limited, as long as the units corresponding to the general formulas (1) and (2) indicating the bonding units A and B are formed. Good.

Examples of the halogen for R ¹ include chlorine, bromine, and fluorine.

Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms of R ¹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert- Examples thereof include a butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group. The number of carbon atoms of the alkyl group is preferably 1-12.

Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms of R ¹ include vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group and 2-pentenyl. Group, 1-hexenyl group, 2-hexenyl group, 1-octenyl group and the like. The alkenyl group preferably has 2 to 12 carbon atoms.

Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms of R ¹ include ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octynyl group, nonynyl group, decynyl group, undecynyl group, Dodecynyl group etc. are mentioned. The alkynyl group preferably has 2 to 12 carbon atoms.

Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms of R ² include ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, Examples include dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, and octadecylene group. The alkylene group preferably has 1 to 12 carbon atoms.

Examples of the branched or unbranched C2-C30 alkenylene group of R ² include vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group and 2-pentenylene. Group, 1-hexenylene group, 2-hexenylene group, 1-octenylene group and the like. The alkenylene group preferably has 2 to 12 carbon atoms.

Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms of R ² include ethynylene group, propynylene group, butynylene group, pentynylene group, hexynylene group, heptynylene group, octynylene group, nonynylene group, decynylene group, undecynylene group, Dodecynylene group etc. are mentioned. The alkynylene group preferably has 2 to 12 carbon atoms.

In the silane coupling agent having the above structure, the total repeating number (x + y) of the repeating number (x) of the bonding unit A and the repeating number (y) of the bonding unit B is preferably in the range of 3 to 300. Within this range, since the mercaptosilane of the bond unit B is covered by —C ₇ H ₁₅ of the bond unit A, it is possible to suppress the scorch time from being shortened and to have good reactivity with silica and rubber components. Can be secured.

As the silane coupling agent having the above structure, for example, NXT-Z30, NXT-Z45, NXT-Z60 manufactured by Momentive, etc. can be used. These may be used alone or in combination of two or more.

The content of the silane coupling agent having the specific mercapto group is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more with respect to 100 parts by mass of silica. Moreover, Preferably it is 20 mass parts or less, More preferably, it is 16 mass parts or less, More preferably, it is 10 mass parts or less. If the amount is less than 1 part by mass, the fuel efficiency deteriorates. If the amount exceeds 20 parts by mass, no further improvement in characteristics such as fuel efficiency and wet grip performance is observed, and an effect commensurate with the increase in cost is achieved. There is a tendency not to be obtained.

In the rubber composition of the present invention, another silane coupling agent may be used in combination.
Examples of other silane coupling agents include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylpropyl) tetrasulfide, and 3-mercapto. Examples thereof include propyltriethoxysilane and 2-mercaptoethyltrimethoxysilane. Of these, bis (3-triethoxysilylpropyl) tetrasulfide and 3-mercaptopropyltriethoxysilane are preferable from the viewpoint of the reinforcing effect and processability of the silane coupling agent, and bis (3- 3-Triethoxysilylpropyl) tetrasulfide is particularly preferred. In addition, the content of the other silane coupling agent is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of silica, and is preferably smaller than the content of the specific mercapto-based silane coupling agent. .

Examples of the saccharide used in the present invention include monosaccharides, disaccharides, trisaccharides, tetrasaccharides, oligosaccharides, polysaccharides, and derivatives thereof (compounds having a similar structure to these and having the same effect). Can be mentioned. Of these, polysaccharides and derivatives thereof are preferred from the standpoint that the effects of the present invention are remarkably obtained. In the present invention, the oligosaccharide is a conjugate of 5 to 9 monosaccharides, and the polysaccharide is a conjugate of 10 or more monosaccharides. Saccharides may be used alone or in combination of two or more.

Monosaccharides and derivatives thereof include trioses (ketotriose, aldotriose, etc.); tetroses (ketototerose, erythrose, throse, etc.); pentoses (ketopentoses such as ribulose, xylulose, ribose, arabinose, xylose) Aldoses such as lyxose, deoxyribose, etc .; hexoses (ketohexoses such as psicose, fructose, sorbose, tagatose, aldohexoses such as allose, altrose, glucose, mannose, gulose, idose, galactose, talose, fucose, Deoxy sugars such as fucose and rhamnose); heptoses (such as cedoheptulose); and derivatives thereof. Of these, fructose is preferable.

Examples of disaccharides and derivatives thereof include α-diglucosides such as trehalose, cordobiose, nigerose, maltose and isomaltose; β-diglucosides such as isotrehalose, sophorose, laminaribiose, cellobiose and gentiobiose; α, β- such as neotrehalose Diglucoside; lactose, sucrose, isomaltulose (palatinose); and derivatives thereof. Of these, maltose is preferable.

Trisaccharides, tetrasaccharides, oligosaccharides and derivatives thereof include raffinose, melezitose, maltotriose, etc .; acarbose, stachyose, etc .; fructooligosaccharide, galactooligosaccharide, xylo-oligosaccharide, isomaltoligosaccharide, chitin oligosaccharide, chitosan oligosaccharide, And cyclic oligosaccharides such as fructooligosaccharide, galactooligosaccharide, mannan oligosaccharide, oligoglucosamine, dextrin, and cyclodextrin; and derivatives thereof.

The weight average molecular weight (Mw) of the polysaccharide and its derivative is preferably 10,000 to 2,000,000, more preferably 50,000 to 1,500,000, and even more preferably 50,000 to 100, from the viewpoint that the effects of the present invention can be obtained satisfactorily. 10,000, particularly preferably 100,000 to 1,000,000. The weight average molecular weight can be determined by high performance anion exchange chromatography (HPAEC) with a pulse amperometric detector or capillary electrophoresis.

Examples of polysaccharides and derivatives thereof include cellulose, starch such as amylose and amylopectin, homopolysaccharides such as glycogen; heteropolysaccharides such as agarose, carrageenan and pectin; mucopolysaccharides such as heparin, chitin and hyaluronic acid; derivatives thereof (Nitrocellulose, acetylcellulose, carboxymethylcellulose, etc.). Of these, starch and chitin are preferred.

The saccharide content is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, with respect to 100 parts by mass of the rubber component. If it is less than 2 parts by mass, the workability and wet grip performance are not sufficiently improved, and there is a possibility that the effect of improving fuel economy and wear resistance may not be obtained. Moreover, Preferably it is 25 mass parts or less, More preferably, it is 20 mass parts or less, More preferably, it is 15 mass parts or less. When the amount exceeds 25 parts by mass, the hardness is remarkably lowered and sufficient hardness cannot be secured, and the effects of the present invention may not be obtained satisfactorily.

In addition to the above components, the rubber composition of the present invention contains compounding agents usually used in the rubber industry, such as zinc oxide, anti-aging agents, softeners (oil etc.), vulcanizing agents, vulcanization accelerators, etc. May be appropriately blended.

Examples of the vulcanizing agent include sulfur. As the sulfur, powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used.

The sulfur content is preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more with respect to 100 parts by mass of the rubber component. Moreover, Preferably it is 3.0 mass parts or less, More preferably, it is 2.0 mass parts or less. If the amount is less than 0.5 parts by mass, the vulcanization rate tends to be slow and the vulcanization tends to be insufficient. On the other hand, if the amount exceeds 3.0 parts by mass, the vulcanization rate tends to be high and scorching tends to occur.

Examples of the vulcanization accelerator include guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, sulfenamide, thiourea, thiuram, dithiocarbamate, and zanddate compounds.

The content of the vulcanization accelerator is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass with respect to 100 parts by mass of the rubber component. Moreover, Preferably it is 4.0 mass parts or less, More preferably, it is 3.0 mass parts or less. If the amount is less than 1.0 part by mass, the vulcanization rate tends to be slow, and vulcanization tends to be insufficient. If the amount exceeds 4.0 parts by mass, the vulcanization rate tends to increase and scorching tends to occur.

The rubber composition of the present invention can be produced by a general method such as a method of kneading the above components with a Banbury mixer, a kneader, an open roll, etc., and then vulcanizing. Specifically, a compounding material other than the vulcanizing agent and the vulcanization accelerator is kneaded at a temperature of 130 to 160 ° C. (base kneading step), then sulfur and a vulcanization accelerator are added, and 80 to 120 ° C. To produce a vulcanized rubber composition by vulcanizing the unvulcanized rubber at a temperature of 150 to 190 ° C. (preferably 160 to 180 ° C.). it can.

The rubber composition of the present invention can be suitably used as a tire tread.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, it is extruded according to the shape of the tread at an unvulcanized stage, molded by a normal method on a tire molding machine, and bonded together with other tire members to form an unvulcanized tire. This unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

The pneumatic tire of the present invention can be applied to various tires such as passenger car tires, truck bus tires, and light truck tires.

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

Various chemicals used in the following examples and comparative examples will be described.
SBR: Asaprene E15 manufactured by Asahi Kasei Chemicals Corporation (S-SBR modified with a polyfunctional compound having two or more epoxy groups in the molecule (coupling), styrene unit amount: 23% by mass)
BR: Ubepol BR150B manufactured by Ube Industries, Ltd.
Silica 1: Ultrasil VN3 manufactured by Degussa (N ₂ SA: 175 m ² / g, DBP oil absorption: 210 ml / 100 g)
Silica 2: Ultrasil 360 manufactured by Degussa (N ₂ SA: 50 m ² / g)
Silica 3: Zeosyl 1205MP (N ₂ SA: 200 m ² / g) manufactured by Rhodia
Silane coupling agent 1: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Silane coupling agent 2: A1891 (3-mercaptopropyltriethoxysilane) manufactured by Momentive
Silane coupling agent 3: NXT-Z15 manufactured by Momentive (copolymer of bonding unit A and bonding unit B (in the above general formulas (1) and (2), bonding unit A: 85 mol%, bonding unit B) : 15 mol%))
Silane coupling agent 4: NXT-Z30 manufactured by Momentive (copolymer of bonding unit A and bonding unit B (in the above general formulas (1) and (2), bonding unit A: 70 mol%, bonding unit B)) : 30 mol%))
Silane coupling agent 5: NXT-Z45 manufactured by Momentive (copolymer of bonding unit A and bonding unit B (in the above general formulas (1) and (2), bonding unit A: 55 mol%, bonding unit B)) : 45 mol%))
Silane coupling agent 6: NXT-Z80 manufactured by Momentive (copolymer of bonding unit A and bonding unit B (in the above general formulas (1) and (2), bonding unit A: 20 mol%, bonding unit B)) : 80 mol%))
Sugar 1: Fructose (monosaccharide) manufactured by Nacalai Tesque
Sugar 2: Maltose (disaccharide) manufactured by Nacalai Tesque
Sugar 3: Corn starch (polysaccharide) manufactured by Nacalai Tesque
Saccharide 4: Chitin (powder) manufactured by Nacalai Tesque, Inc. (polysaccharide: β-1,4-poly-N-acetyl-D-glucosamine)
Oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Zinc oxide: Zinc oxide stearic acid manufactured by Mitsui Mining & Smelting Co., Ltd .: Stearic acid “Kashiwa” manufactured by NOF Corporation
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. 1: Noxeller CZ manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator 2: Noxeller D from Ouchi Shinsei Chemical Co., Ltd.

<Examples and Comparative Examples>
In accordance with the formulation shown in Tables 1 and 2, materials other than sulfur and a vulcanization accelerator were kneaded at 160 ° C. for 3 minutes using a 1.7 L Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 3 minutes at 80 ° C. using an open roll to obtain an unvulcanized rubber composition.

The obtained unvulcanized rubber composition was extruded into a sheet and molded into a tread portion of a tire to produce a trial tire (size: 195 / 65R15).

The following evaluation was performed about the obtained unvulcanized rubber composition and trial manufacture tire. The results are shown in Tables 1-2.

<Processability (Mooney viscosity)>
With respect to the unvulcanized rubber composition, Mooney viscosity (ML _{1 + 4} ) was measured at 130 ° C. using MV202 manufactured by Shimadzu Corporation based on JIS K6301. The value of the Mooney viscosity of Comparative Example 1 was taken as 100, and the Mooney viscosity of each formulation was displayed as an index. The Mooney viscosity indicates that the smaller the index value, the better the workability.

<Low fuel consumption (rolling resistance)>
Using a rolling resistance tester, the rolling resistance value when a prototype tire is mounted on a 15 × 6JJ rim and run at an internal pressure of 230 kPa, a load of 3.43 kN, and a speed of 80 km / h is measured. The rolling resistance value of each formulation was displayed as an index with 1 being 100. The larger the index, the better the rolling resistance performance and the better the fuel efficiency.

<Wet grip performance>
The distance of Comparative Example 1 was measured by measuring the braking distance until stopping when braking at 100 km / h on a test course on an asphalt road surface with water sprayed on a traction test vehicle equipped with a prototype tire. The wet grip performance of each formulation was indicated as an index with 100 being 100. The larger the index, the better the wet grip performance.

<Abrasion resistance>
The vehicle was run with a prototype tire mounted, and the change in the groove depth of the tread pattern during running of 30000 km was measured. The amount of wear of each formulation was displayed as an index, with the amount of wear of Comparative Example 1 being 100. The larger the index, the better the wear resistance.

<Steering stability>
The prototype tires were mounted on all wheels of domestic FF2000cc, and the vehicle was run on the test course, and the steering stability was evaluated by sensory evaluation of the driver. Evaluation was made into a 10-point full scale, and the comparative example 1 was made into 6 points and relative evaluation was carried out. The larger the score, the better the steering stability.

From Tables 1 and 2, by using a silane coupling agent having a specific mercapto group and a monosaccharide or disaccharide in combination, by using the silane coupling agent and a polysaccharide together, while maintaining good processability, It has been clarified that the performance balance of low fuel consumption, wet grip performance, wear resistance and handling stability, particularly the low fuel consumption, wet grip performance and wear resistance performance balance can be synergistically improved. Further, when silica having two specific types of nitrogen adsorption specific surface areas was used, wet grip performance and wear resistance could be remarkably improved. Moreover, when a polysaccharide was used as the saccharide, a synergistic effect was more effectively exhibited.

Claims (7)

It contains a rubber component, silica, a binding unit A represented by the following general formula (1) and a binding unit B represented by the following general formula (2), and the content of the binding unit B is 1 to 70 mol%. A tire rubber composition comprising a silane coupling agent having a mercapto group and a saccharide.

Wherein R ¹ is hydrogen, halogen, branched or unbranched alkyl group having 1 to 30 carbon atoms, branched or unbranched alkenyl group having 2 to 30 carbon atoms, branched or unbranched carbon group having 2 to 30 carbon atoms. An alkynyl group, or a group in which the terminal hydrogen of the alkyl group is substituted with a hydroxyl group or a carboxyl group, R ² represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched carbon number of 2 30 represents an alkenylene group or a branched or unbranched alkynylene group having 2 to 30 carbon atoms, and R ¹ and R ² may form a ring structure.) The tire rubber composition according to claim 1, wherein the saccharide is at least one selected from the group consisting of monosaccharides, disaccharides, trisaccharides, tetrasaccharides, oligosaccharides, and derivatives thereof. The tire rubber composition according to claim 1, wherein the saccharide is a polysaccharide and / or a derivative thereof. The rubber composition for a tire according to any one of claims 1 to 3, wherein the content of the silica is 15 to 150 parts by mass and the content of the saccharide is 2 to 25 parts by mass with respect to 100 parts by mass of the rubber component. object. The silica is silica (I) having a nitrogen adsorption specific surface area of 100 m ² / g or less and silica (II) having a nitrogen adsorption specific surface area of 180 m ² / g or more, and the silica with respect to 100 parts by mass of the rubber component The rubber for tire according to any one of claims 1 to 4, wherein the total content of (I) and (II) is 10 to 150 parts by mass, and the content of silica (I) and (II) satisfies the following formula: Composition.
(Content of silica (I)) × 0.2 ≦ (content of silica (II)) ≦ (content of silica (I)) × 6.5 The tire rubber composition according to any one of claims 1 to 5, wherein a content of the styrene-butadiene rubber is 30% by mass or more in 100% by mass of the rubber component. The pneumatic tire which has a tread produced using the rubber composition in any one of Claims 1-6.