WO2016167289A1

WO2016167289A1 - Rubber composition and tire

Info

Publication number: WO2016167289A1
Application number: PCT/JP2016/061919
Authority: WO
Inventors: 加藤　学; 亮太高橋; 隆裕岡松; 美昭桐野
Original assignee: 横浜ゴム株式会社
Priority date: 2015-04-14
Filing date: 2016-04-13
Publication date: 2016-10-20
Also published as: JPWO2016167289A1

Abstract

The purpose of the present invention is to provide a rubber composition that has excellent low heat generation and excellent wear resistance. The present invention is a rubber composition that is for a tire tread and that contains: a rubber component that includes at least a modified diene rubber wherein 0.02-4 mol% of the total double bonds of a source-material diene rubber have been carboxy-group modified; a silica 1 that has a nitrogen-adsorption specific surface area of 155 m²/g or higher; a silica 2 that has a nitrogen-adsorption specific surface area of 125 m²/g or lower; and a silane coupling agent. The modified diene rubber content is 10-100 parts by mass per 100 parts by mass of the rubber component, the total content of the silica 1 and the silica 2 is 55-200 parts by mass per 100 parts by mass of the rubber component, and the silane coupling agent content is 2-16 mass% of said total content. The present invention is also a tire that has a tire tread that uses the rubber composition.

Description

Rubber composition and tire

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

Conventionally, tires are required to have excellent wet performance, low heat generation, wear resistance, and the like. However, if wet performance and low heat build-up are excellent, wear resistance may be sacrificed.
For this reason, for example, Patent Document 1 has been proposed for the purpose of improving the low rolling resistance, wet grip property and wear resistance from the conventional level.
Patent Document 1 discloses that 100 wt. Of diene rubber containing 5 to 50 wt.% Of terminally modified solution-polymerized styrene butadiene rubber (modified S-SBR) having a vinyl unit content of 25 wt% or more and a glass transition temperature of −50 ° C. or less. 2 to 50 parts by weight of an aromatic modified terpene resin having a softening point of 100 ° C. or higher, and 60 to 130 parts by weight of two types of silica X and silica Y in total, and the modified S-SBR The functional group is reactive with silanol groups on the silica surface, the ratio of silica to the total amount of the reinforcing filler containing silica and carbon black is 85% by weight or more, and the nitrogen adsorption specific surface area of the silica X is 140 m ^2. / g or more, the nitrogen adsorption specific surface area of the silica Y is less than 140 m ² / g exceed 100 m ² / g, and distribution of the silica X with respect to the diene rubber 100 parts by weight The amount of x parts by weight, when the amount of the silica Y and y parts by weight, tire rubber composition characterized by satisfying the relation of x / 7 <y ≦ x is described.

JP 2013-227375 A

When the present inventors prepared and evaluated the rubber composition containing 2 types of silica from which a nitrogen adsorption specific surface area differs based on patent document 1, such a rubber composition had abrasion resistance fallen. It has become clear that there is room for improvement in low exothermicity.
In view of the above circumstances, an object of the present invention is to provide a rubber composition excellent in low heat buildup and wear resistance.
Another object of the present invention is to provide a tire.

As a result of intensive studies to solve the above problems, the present inventors have found that the rubber composition contains a modified diene rubber modified with a carboxy group at a modification rate within a specific range, whereby a predetermined effect can be obtained. The headline, the present invention has been reached.
The present invention is based on the above knowledge and the like, and specifically, solves the above problems by the following configuration.

1. A rubber component containing at least a modified diene rubber in which 0.02 to 4 mol% of the total amount of double bonds of the raw diene rubber is modified with a carboxy group;
Silica 1 having a nitrogen adsorption specific surface area of 155 m ² / g or more;
Silica 2 having a nitrogen adsorption specific surface area of 125 m ² / g or less;
Containing a silane coupling agent,
The content of the modified diene rubber is 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component,
The total content of the silica 1 and the silica 2 is 55 to 200 parts by mass with respect to 100 parts by mass of the rubber component,
A rubber composition for a tire tread, wherein the content of the silane coupling agent is 2 to 16% by mass of the total content.
2. 2. The rubber composition according to 1 above, wherein the ratio of the content of the silica 1 to the content of the silica 2 (silica 1 / silica 2) is 2 to 10.
3. 3. The rubber composition according to 1 or 2 above, wherein the modified diene rubber is produced by reacting the raw diene rubber with a nitrone compound having a carboxy group and a nitrone group.
4). The nitrone compound is
N-phenyl-α- (4-carboxyphenyl) nitrone,
N-phenyl-α- (3-carboxyphenyl) nitrone,
N-phenyl-α- (2-carboxyphenyl) nitrone,
N- (4-carboxyphenyl) -α-phenylnitrone,
4. The rubber composition according to 3 above, which is at least one selected from the group consisting of N- (3-carboxyphenyl) -α-phenylnitrone and N- (2-carboxyphenyl) -α-phenylnitrone.
5. The rubber composition according to 3 or 4 above, wherein the content of the nitrone compound introduced into the modified diene rubber is 0.3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component. .
6). A rubber component having at least a modified diene rubber having a double bond and a carboxy group, wherein the content of the carboxy group is 0.2 to 4 mol% of the total of the double bond and the carboxy group;
Silica 1 having a nitrogen adsorption specific surface area of 155 m ² / g or more;
Silica 2 having a nitrogen adsorption specific surface area of 125 m ² / g or less;
Containing a silane coupling agent,
The content of the modified diene rubber is 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component,
The total content of the silica 1 and the silica 2 is 55 to 200 parts by mass with respect to 100 parts by mass of the rubber component,
A rubber composition for a tire tread, wherein the content of the silane coupling agent is 2 to 16% by mass of the total content.
7). A tire using the rubber composition according to any one of the above 1 to 6 for a tire tread.

In the present invention, the modified diene rubber contained in the rubber composition described in 6 above corresponds to the modified diene rubber contained in the rubber composition described in 1 above. In the present invention, the modified diene rubber is any one of the modified diene rubber contained in the rubber composition described in 6 above and the modified diene rubber contained in the rubber composition described in 1 above. If it is.
The components other than the modified diene rubber in the rubber composition described in 6 above are the same as the components other than the modified diene rubber in the rubber composition described in 1 above.

The rubber composition of the present invention is excellent in low heat buildup and wear resistance.
The tire of the present invention is excellent in low heat buildup and wear resistance.

It is a partial section schematic diagram of the tire showing an example of an embodiment of a tire of the present invention.

The present invention will be described in detail below.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Moreover, in this specification, when a component contains 2 or more types of substances, content of the said component refers to the total content of 2 or more types of substances.

The rubber composition of the present invention is
A rubber component containing at least a modified diene rubber in which 0.02 to 4 mol% of the total amount of double bonds of the raw diene rubber is modified with a carboxy group;
Silica 1 having a nitrogen adsorption specific surface area of 155 m ² / g or more;
Silica 2 having a nitrogen adsorption specific surface area of 125 m ² / g or less;
Containing a silane coupling agent,
The content of the modified diene rubber is 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component,
The total content of the silica 1 and the silica 2 is 55 to 200 parts by mass with respect to 100 parts by mass of the rubber component,
A rubber composition for a tire tread, wherein the content of the silane coupling agent is 2 to 16% by mass of the total content.

Since the rubber composition of the present invention has such a configuration, it is considered that a desired effect can be obtained. The reason is not clear, but it is presumed that it is as follows.
When silica with a large nitrogen adsorption specific surface area and silica with a small nitrogen adsorption specific surface area are used in combination, silica with a small nitrogen adsorption specific surface area is unlikely to interact with rubber, so silica is difficult to disperse in the rubber component, low heat build-up, etc. The effect of is difficult to obtain.
On the other hand, a modified diene rubber modified to a carboxy group at a specific modification rate can interact and / or bond with silica. Since the modified diene rubber can interact strongly with two types of silica having different nitrogen adsorption specific surface areas and different reinforcing properties, by using a modified diene rubber and a silane coupling agent in combination, Silica can be further dispersed.
Therefore, it is considered that further low heat build-up and wear resistance could be improved by using the modified diene rubber.

[Rubber composition]
Hereinafter, each component contained in the rubber composition of the present invention will be described in detail.
<< Rubber component >>
The rubber component contained in the rubber composition of the present invention contains at least a modified diene rubber.

<Modified diene rubber>
The modified diene rubber contained in at least the rubber component is a modified diene rubber in which 0.02 to 4 mol% of the total amount of double bonds of the raw diene rubber is modified with carboxy groups. In the present specification, the ratio of the carboxy group (mol) of the modified diene rubber to the total amount (mol) of double bonds of the raw diene rubber, or the double bond and carboxy of the modified diene rubber. The ratio of the carboxy group (mole) to the total group (mole) may be referred to as the modification rate. That is, in the present invention, the modification rate is 0.02 to 4 mol%.

In the present invention, the modified diene rubber has a double bond and a carboxy group, and the content of the carboxy group is 0.2 to 4 mol% of the total of the double bond and the carboxy group.
In the present invention, the modified diene rubber has a carboxy group as a modifying group.

(Modified group)
The modified diene rubber can have a carboxy group as a modifying group in at least one of the main chain and the side chain. Further, at least a part of the main chain or at least a part of the side chain of the modified diene rubber can have a carboxy group as a modifying group.

Examples of the modifying group in the main chain include a group represented by the following formula (I).
Examples of the modifying group in the side chain include a group represented by the following formula (II).

In the above formula (I), each of a21 and a22 is preferably independently 0 to 5, more preferably 0, 1 or 2.
a21 + a22 is preferably 1 or more, more preferably 1 to 4, and still more preferably 1 to 2.

In formula (I), a21, a22, and a21 + a22 are the same as n, m, and m + n in formula (3) described later, respectively.

In the above formula (II), each of a31 and a32 is preferably independently 0 to 5, more preferably 0, 1 or 2.
a31 + a32 is preferably 1 or more, more preferably 1 to 4, and still more preferably 1 to 2.

A31, a32, a31 + a32 in the formula (II) are the same as n, m, m + n in the formula (3) to be described later.

Examples of the main chain of the modified diene rubber include those similar to the diene rubber used as the raw material diene rubber described later. Among these, aromatic vinyl-conjugated diene copolymer rubber is preferable and styrene butadiene rubber is more preferable from the viewpoint of excellent low heat build-up and excellent strength characteristics.

(Method for producing modified diene rubber)
The modified diene rubber has at least one of low exothermic property and wear resistance (hereinafter referred to as “the effect of the present invention is more excellent”), so that the raw material diene rubber and a modifier having a carboxy group are used. What is manufactured by making it react is preferable.

The modified diene rubber is preferably modified with a carboxy group in one or both of the main chain and the side chain.

-Raw material diene rubber The diene rubber used as the raw material diene rubber is not particularly limited. For example, natural rubber (NR), isoprene rubber (IR), aromatic vinyl-conjugated diene copolymer rubber, acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (for example, Br-IIR, Cl-IIR) and chloroprene rubber (CR). Among these, aromatic vinyl-conjugated diene copolymer rubber is preferable and styrene butadiene rubber is more preferable from the viewpoint of excellent low heat build-up and excellent strength characteristics.

The styrene butadiene rubber (SBR) that can be used as the raw material diene rubber is not particularly limited as long as it is a copolymer of styrene and butadiene. Styrene butadiene rubber is excellent in reactivity with the modifier because of its small steric hindrance in the unsaturated bond derived from butadiene.

The amount of styrene contained in the styrene butadiene rubber is preferably 10% by mass or more, more preferably 26 to 70% by mass, based on all the structural units constituting the styrene butadiene rubber, from the viewpoint of excellent compatibility with the modifier.
Here, the styrene content of the styrene butadiene rubber refers to the ratio (mass% or weight%) of the styrene unit in all the structural units constituting the styrene butadiene rubber.
In the present invention, the microstructure of the styrene butadiene rubber was measured according to JIS K 6239: 2007 (raw material rubber-solution polymerization SBR microstructure determination method).

Examples of the double bond derived from butadiene in the styrene-butadiene rubber include 1,4-bond (cis-1,4-bond, trans-1,4-bond) and 1,2-bond.
The proportion of 1,4-bonds in the double bonds of the styrene butadiene rubber is preferably 20 to 80 mol%, more preferably 25 to 65 mol%, based on the total amount of double bonds.
Here, the proportion of 1,4-bonds in the double bonds of styrene-butadiene rubber refers to all double bonds of styrene-butadiene rubber (trans-1,4 units of butadiene component, cis-1,4 1 and 4 units (1,4-bond) (unit: mol%).

The proportion of 1,2-bonds in the double bonds of styrene-butadiene rubber (vinyl amount or vinyl bond amount) is preferably 20 to 80 mol%, and 35 to 75 mol% in the total amount of double bonds. Is more preferable.
Here, the proportion of 1,2-bonds in the double bonds of styrene butadiene rubber means 1,2 units (1,2-bonds) of all double bonds of styrene butadiene rubber. It refers to the ratio (mol%).

The glass transition temperature of the raw diene rubber is not particularly limited. For example, from the viewpoint of better wear resistance, it is preferably −20 ° C. or lower.
When the raw diene rubber is an aromatic vinyl-conjugated diene copolymer rubber, it is preferably −20 ° C. or lower and −80 ° C. or higher.
When the raw diene rubber is other than aromatic vinyl-conjugated diene copolymer rubber, it is preferably -50 to -80 ° C.
The glass transition temperature is measured by using a differential scanning calorimeter (DSC) at a rate of temperature increase of 20 ° C./min and calculated by the midpoint method.

The weight average molecular weight of the raw material diene rubber is preferably 100,000 to 1,500,000, more preferably 100,000 to 1,400,000 from the viewpoint of handleability, and 300,000. More preferably, it is ˜1,300,000. The weight average molecular weight (Mw) of the raw material diene rubber is measured in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

-Modifying agent The modifying agent that can be used when producing the modified diene rubber is described below. The denaturing agent is preferably a compound having at least a carboxy group, and more preferably a nitrone compound having a carboxy group and a nitrone group.

The number of carboxy groups per molecule in the modifier is preferably 1 or more, can be 10 or less, more preferably 1 to 4, and more preferably 1 to 2. preferable.

The nitrone group is a group represented by the following formula (1).

In the above formula (1), * represents a bonding position.
The number of nitrone groups per molecule in the denaturant is preferably 1 to 3.

The modifying agent is preferably a compound represented by the following formula (2).

In the above formula (2), X and Y each independently represent an aliphatic hydrocarbon group, an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. The carboxy group can be attached to one or both of X and Y.

Examples of the aliphatic hydrocarbon group represented by X or Y include an alkyl group, a cycloalkyl group, and an alkenyl group.
Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, Examples thereof include a tert-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, n-hexyl group, n-heptyl group, n-octyl group and the like.
Of these, an alkyl group having 1 to 18 carbon atoms is preferable, and an alkyl group having 1 to 6 carbon atoms is more preferable.

Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like.
Of these, a cycloalkyl group having 3 to 10 carbon atoms is preferable, and a cycloalkyl group having 3 to 6 carbon atoms is more preferable.

Examples of the alkenyl group include a vinyl group, 1-propenyl group, allyl group, isopropenyl group, 1-butenyl group, 2-butenyl group and the like.
Of these, an alkenyl group having 2 to 18 carbon atoms is preferable, and an alkenyl group having 2 to 6 carbon atoms is more preferable.

Examples of the aromatic hydrocarbon group represented by X or Y include an aryl group and an aralkyl group.
Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group. Among them, an aryl group having 6 to 14 carbon atoms is preferable, and an aryl group having 6 to 10 carbon atoms is more preferable. A phenyl group and a naphthyl group are more preferable.
Examples of the aralkyl group include a benzyl group, a phenethyl group, and a phenylpropyl group. Among them, an aralkyl group having 7 to 13 carbon atoms is preferable, an aralkyl group having 7 to 11 carbon atoms is more preferable, and a benzyl group is preferable. Further preferred.

Examples of the aromatic heterocyclic group represented by X or Y include, for example, pyrrolyl group, furyl group, thienyl group, pyrazolyl group, imidazolyl group (imidazole group), oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, pyridyl group. (Pyridine group), furan group, thiophene group, pyridazinyl group, pyrimidinyl group, pyrazinyl group and the like. Of these, a pyridyl group is preferable.

The substituent other than the carboxy group that the group represented by X or Y may have is not particularly limited, and examples thereof include an alkyl group having 1 to 4 carbon atoms, a hydroxy group, an amino group, a nitro group, and a sulfonyl group. Group, alkoxy group, halogen atom and the like.
In addition, examples of the aromatic hydrocarbon group having such a substituent include aryl groups having an alkyl group such as tolyl group and xylyl group; substituents such as methylbenzyl group, ethylbenzyl group, and methylphenethyl group. An aralkyl group having the following: and the like.

The modifier is preferably a compound represented by the following formula (3) from the viewpoint of excellent compatibility and reactivity with the raw material diene rubber.

In formula (3), m and n each independently represent an integer of 0 to 5, and the sum of m and n is 1 or more.
The integer represented by m is preferably an integer of 0 to 2, and more preferably an integer of 0 to 1, because the solubility in a solvent at the time of synthesizing a modifier is improved and the synthesis is facilitated.
The integer represented by n is preferably an integer of 0 to 2, more preferably an integer of 0 to 1, because the solubility in a solvent at the time of synthesizing a modifier is improved and the synthesis is facilitated.
The total of m and n (m + n) is preferably 1 to 4, and more preferably 1 to 2.

The modifier is N-phenyl-α- (4-carboxyphenyl) nitrone represented by the following formula (3-1), N-phenyl-α- (3-carboxyl represented by the following formula (3-2). Phenyl) nitrone, N-phenyl-α- (2-carboxyphenyl) nitrone represented by the following formula (3-3), N- (4-carboxyphenyl) -α represented by the following formula (3-4) -Phenylnitrone, N- (3-carboxyphenyl) -α-phenylnitrone represented by the following formula (3-5), and N- (2-carboxyphenyl) represented by the following formula (3-6) It is preferably at least one selected from the group consisting of -α-phenylnitrone.

The method for synthesizing the modifier is not particularly limited, and a conventionally known method can be used. For example, a compound having a hydroxyamino group (—NHOH) and a compound having an aldehyde group (—CHO) have a molar ratio of hydroxyamino group to aldehyde group (—NHOH / —CHO) of 1.0 to 1. By stirring in an organic solvent (for example, methanol, ethanol, tetrahydrofuran, etc.) at room temperature for 1 to 24 hours in an amount of 5, a compound having a nitrone group can be produced by reacting both groups. In the above, any one or both of the compound having a hydroxyamino group and the compound having an aldehyde group may have a carboxy group. When the modifier further has a substituent other than a carboxy group, either one or both of the compound having a hydroxyamino group and the compound having an aldehyde group can have the above substituent.

The production method of the modified diene rubber is not particularly limited, and examples thereof include a method of mixing the raw diene rubber and the modifier at 100 to 200 ° C. for 1 to 30 minutes.

The amount of the modifying agent (eg, nitrone compound) used in producing the modified diene rubber is preferably 0.3 to 10 parts by mass with respect to 100 parts by mass of the raw diene rubber. More preferred is 3 parts by mass.

<Modification rate>
In the present invention, the modified diene rubber is a modified diene rubber in which 0.02 to 4 mol% of the total amount of double bonds of the raw diene rubber is modified with carboxy groups, or double bonds and carboxy groups. A modified diene rubber having a carboxy group content of 0.2 to 4 mol% of the total of double bonds and carboxy groups.
In the present invention, the modification rate is 0.02 to 4 mol%. The above modification rate is preferably 0.10 to 3 mol%, more preferably 0.15 to 2 mol%, from the viewpoint of being excellent in a predetermined effect.

In the present invention, the modification rate can be determined, for example, by performing NMR (nuclear magnetic resonance) measurement of the raw diene rubber and the modified diene rubber. Specifically, the raw diene rubber and the modified diene rubber were subjected to ¹ H-NMR measurement (CDCl ₃ , 400 MHz, TMS: tetramethylsilane) using CDCl ₃ as a solvent, and around 8.08 ppm (with carboxy group) (Specifically, when a carboxy group is bonded to a benzene ring, it belongs to two protons bonded to a carbon atom adjacent to the carbon atom to which the carboxy group is bonded.) Was measured to calculate the denaturation rate.

The content of the modifying agent (for example, nitrone compound) introduced into the modified diene rubber is 0.3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component because the effect of the present invention is more excellent. Preferably, the amount is 0.3 to 5 parts by mass.

Modified diene rubbers can be used alone or in combination of two or more.

<Content of modified diene rubber>
In the present invention, the content of the modified diene rubber is 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component. The content of the modified diene rubber is preferably 20 to 80 parts by mass, more preferably 25 to 70 parts by mass with respect to 100 parts by mass of the rubber component, from the viewpoint that the effects of the present invention are more excellent. .

In the present invention, the rubber component may further contain a rubber other than the modified diene rubber. Examples of the rubber other than the modified diene rubber include a diene rubber. The diene rubber is not particularly limited. Examples thereof include the same raw material diene rubbers that can be used when producing a modified diene rubber.
Among these, at least one selected from the group consisting of natural rubber, styrene butadiene rubber and butadiene rubber is preferable.
Natural rubber, styrene butadiene rubber and butadiene rubber are not particularly limited. For example, it can be the same as the raw material diene rubber.

The average glass transition temperature of the rubber component is preferably −50 ° C. or less, and can be −50 to −80 ° C., because the hardness of the tire can be kept low even at low temperatures and the performance on the ice of the tire is good. It is more preferable that The average glass transition temperature is an average value of the glass transition temperature. When only one type of modified diene rubber is used as the rubber component, it means the glass transition temperature of the modified diene rubber. When two or more kinds of modified diene rubbers are used as the rubber component, or when the modified diene rubber and other rubber are used in combination, the average value of the glass transition temperature of the entire rubber component is meant. In this case, the average glass transition temperature can be calculated from the glass transition temperature of each rubber and the blending ratio of each rubber.

<Silica 1>
Silica 1 contained in the rubber composition of the present invention is not particularly limited as long as its nitrogen adsorption specific surface area (N ₂ SA) is 155 m ² / g or more. For example, a conventionally well-known thing is mentioned.

In the present invention, the nitrogen adsorption specific surface area of silica is measured in accordance with JIS K6430.

Nitrogen adsorption specific surface area of the silica 1 from the viewpoint of the effect of the present invention more excellent, preferably 155 ~ 250m ² / g, more preferably 160 ~ 200m ² / g.

Specific examples of the silica 1 include fumed silica, calcined silica, precipitated silica, pulverized silica, fused silica, colloidal silica, and the like.
Silica 1 can be used alone or in combination of two or more.

<Silica 2>
Silica 2 contained in the rubber composition of the present invention is not particularly limited as long as its nitrogen adsorption specific surface area is 125 m ² / g or less.

Nitrogen adsorption specific surface area of the silica ₂ (N 2 SA), from the viewpoint that the effect of the present invention more excellent, preferably 80 ~ 125m ² / g, more preferably 100 ~ 120m ² / g.

Specific examples of silica include fumed silica, calcined silica, precipitated silica, pulverized silica, fused silica, colloidal silica, and the like.

<Total content of silica 1 and silica 2>
In the present invention, the total content of silica 1 and silica 2 is 55 to 200 parts by mass with respect to 100 parts by mass of the rubber component. The total content of silica 1 and silica 2 is preferably 55 to 180 parts by mass, and preferably 55 to 160 parts by mass with respect to 100 parts by mass of the rubber component, from the viewpoint that the effects of the present invention are more excellent. More preferred.

(Silica 1 / Silica 2)
The ratio of the content of silica 1 to the content of silica 2 (silica 1 / silica 2. mass ratio) is preferably 2 to 10 from the viewpoint that the effect of the present invention is more excellent, and 2.2 to 5 More preferably, it is more preferably 2.4 to 2.8.

<Silane coupling agent>
The silane coupling agent contained in the rubber composition of the present invention is not particularly limited.
Specific examples of the silane coupling agent include silane coupling agents containing a sulfur atom such as mercaptosilane and sulfide silane.
Examples of mercaptosilane include C ₁₃ H ₂₇ O— (CH ₂ CH ₂ O) ₅ ] ₂ (CH ₂ CH ₂ O) Si (CH ₂ ) ₂ SH: 3-mercaptopropyltrimethoxysilane, 3-mercapto Examples include a silane coupling agent having a mercapto group such as propyltriethoxysilane.
Examples of the sulfide silane include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (2-trimethoxysilyl). Ethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide A silane coupling agent having a (poly) sulfide bond such as
A silane coupling agent can be used individually or in combination of 2 types or more, respectively.

<Content of silane coupling agent>
In the present invention, the content of the silane coupling agent is 2 to 16% by mass of the total content of silica 1 and silica 2. The content of the silane coupling agent is preferably 2 to 14% by mass, and preferably 3 to 12% by mass, based on the total content of silica 1 and silica 2, from the viewpoint that the effects of the present invention are more excellent. More preferred.

(Other ingredients)
The rubber composition of the present invention may further contain an additive as long as the effect and purpose are not impaired. As the additive, for example, rubber other than the diene rubber, the silica other than the filler (e.g., silica 1,2 other than silica (e.g., nitrogen adsorption specific surface area of 125m ² / g to greater than less than 155m ² / g A certain silica), carbon black, clay, mica, talc, calcium carbonate, aluminum hydroxide, aluminum oxide, titanium oxide), vulcanization accelerator, resin such as terpene resin, zinc oxide, stearic acid, anti-aging agent, Examples of the rubber composition for tires generally used include processing aids, oils (for example, aroma oil, process oil), liquid polymers, thermosetting resins, and vulcanizing agents such as sulfur. The content of the additive can be appropriately selected.

Carbon black The rubber composition of the present invention preferably further contains carbon black.
The carbon black is not particularly limited, and, for example, SAF (Super Ablation Furnace; the same applies hereinafter) -HS (High Structure, the same applies hereinafter), SAF, ISAF (Intermediate Super Absorption Furnace, the same applies hereinafter) -HS, ISAF, IS-AF LS (Low Structure. Same as below), IISAF (Intermediate ISAF)-HS, HAF (High Ablation Furnace. Same as below)-HS, HAF, HAF-LS, FEF (Fast Extruding Furnace) be able to.

The CAB (abbreviation for n-hexadecyltrimethylammonium bromide) adsorption specific surface area of carbon black is not particularly limited. CTAB adsorption specific surface area of carbon black, from the viewpoint of the effect of the present invention is more excellent, preferably 60 ~ 250m ² / g, more preferably 90 ~ 200m ² / g. Here, the CTAB adsorption specific surface area of carbon black was measured according to the CTAB adsorption method described in JIS K 6217-3.

The content of carbon black is not particularly limited, but is preferably 5 to 70 parts by mass, more preferably 8 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

-Terpene-type resin The rubber composition of this invention can contain a terpene-type resin further. The terpene resin may be a polymer that uses at least a terpene monomer as a monomer, and may be either a homopolymer or a copolymer. The terpene resin may be modified with, for example, an aromatic compound.
Examples of the terpene monomer include α-pinene, β-pinene, dipentene, limonene, and derivatives thereof.
Examples of aromatic compounds include styrene, α-methylstyrene, vinyl toluene, indene, and phenols.

Examples of the terpene resin include aromatic modified terpene resins. The terpene resin is preferably an aromatic modified terpene resin.
The softening point of the terpene resin (especially aromatic modified terpene resin) is preferably 60 to 150 ° C., more preferably 70 to 130 ° C.
The terpene resin is not particularly limited for its production. For example, a conventionally well-known thing is mentioned. The terpene resins can be used alone or in combination of two or more.

The amount of the terpene resin is preferably 1 to 30 parts by mass, more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

(Method for producing rubber composition)
The method for producing the rubber composition of the present invention is not particularly limited, and specific examples thereof include, for example, kneading the above-described components using a known method and apparatus (for example, a Banbury mixer, a kneader, a roll, etc.). The method of doing is mentioned.
The rubber composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.
A tire can be manufactured using the rubber composition of the present invention. The rubber composition of the present invention is used for a tire tread. You may use the rubber composition of this invention for parts other than the tire tread of a tire.

[tire]
The tire of the present invention is a tire using the rubber composition of the present invention for a tire tread.
The tire of the present invention is not particularly limited as long as the tire tread is manufactured (formed) using the rubber composition of the present invention.
The rubber composition used for the tire tread is not particularly limited as long as it is the rubber composition of the present invention.

タイヤ Parts of the tire other than the tire tread to which the rubber composition is applied are not particularly limited. You may use the rubber composition of this invention for a tire tread, a bead part, a sidewall part, etc.

One preferred embodiment of the tire of the present invention is a pneumatic tire.
The tire of the present invention will be described below with reference to the accompanying drawings. The tire of the present invention is not limited to the attached drawings.

FIG. 1 is a schematic partial sectional view of a tire representing an example of an embodiment of a tire according to the present invention. The tire shown in FIG. 1 is a pneumatic tire.
In FIG. 1, reference numeral 1 represents a bead portion, reference numeral 2 represents a sidewall portion, and reference numeral 3 represents a tire tread. The tire tread 3 is manufactured using the rubber composition of the present invention.
Further, a carcass layer 4 in which fiber cords are embedded is mounted between the pair of left and right bead portions 1, and the end of the carcass layer 4 extends from the inside of the tire to the outside around the bead core 5 and the bead filler 6. Wrapped and rolled up.
In the tire tread 3, a belt layer 7 is disposed over the circumference of the tire on the outside of the carcass layer 4.
Moreover, in the bead part 1, the rim cushion 8 is arrange | positioned in the part which touches a rim | limb.

The tire of the present invention can be manufactured, for example, according to a conventionally known method.
When the tire of the present invention is a pneumatic tire, the gas filled in the pneumatic tire can be normal or air having an adjusted partial pressure of oxygen, or an inert gas such as nitrogen, argon, or helium. .

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

<Synthesis of Nitrone Compound 1>
Methanol (900 mL) warmed to 40 ° C. was placed in a 2 L eggplant flask, and terephthalaldehyde acid (30.0 g) represented by the following formula (b-1) was added and dissolved therein. A solution of phenylhydroxyamine (21.8 g) represented by the following formula (a-1) in methanol (100 mL) was added to this solution, and the mixture was stirred at room temperature for 19 hours. After completion of the stirring, nitrone compound (carboxynitrone, CPN) represented by the following formula (c-1) was obtained by recrystallization from methanol (41.7 g). The yield was 86%. The obtained nitrone compound is designated as nitrone compound 1. The molecular weight of the nitrone compound 1 is 241.

<Manufacture of modified diene rubber 1>
137.5 parts by mass of raw material SBR [styrene butadiene rubber, trade name E581, oil extended amount with respect to 100 parts by mass of net SBR: 37.5 parts by mass, weight average molecular weight: 1,200,000, styrene content: 37% by mass, vinyl bond Amount: 43%, glass transition temperature -27 ° C., manufactured by Asahi Kasei Chemical Co., Ltd.] and nitrone compound 1 (1 part by mass) with a mixer at 160 ° C. for 5 minutes to mix the above raw material SBR with nitrone compound 1 A modified diene rubber 1 modified with 1 was obtained.

In the above production, 0.22 mol% of the total amount of double bonds of the raw material SBR was modified by the nitrone compound 1 to a carboxy group.
The modified diene rubber 1 had a double bond and a carboxy group, and the content of the carboxy group was 0.22 mol% of the total of the double bond and the carboxy group.
The modification rate of the modified diene rubber 1 was 0.22 mol%.

<Manufacture of rubber composition>
Using each component shown in Table 1 below in the amount (parts by mass) shown in the same table, these were blended to produce a rubber composition. Specifically, first, among the components shown in Table 1 below, components other than sulfur and a vulcanization accelerator (CZ) were mixed for 5 minutes with a Banbury mixer at 80 ° C. to obtain a mixture. Next, the sulfur and the vulcanization accelerator were added to the mixture, and these were mixed using a roll to obtain a rubber composition.

In addition, when the usage-amount of the modified diene rubber 1 used in Table 1 is 40 parts by mass, the content of the net modified diene rubber contained in this is 29 parts by mass.

The content (CPN amount) of the nitrone compound 1 contained in the net 29 parts by mass of the modified diene rubber 1 is 0.32 parts by mass.

When the amount of SBR used in Table 1 is 28.75 parts by mass, the content of the net styrene butadiene rubber contained therein is about 21 parts by mass.

<Preparation of vulcanized rubber sheet>
The rubber composition (unvulcanized) produced as described above was press-vulcanized at 160 ° C. for 20 minutes in a mold (15 cm × 15 cm × 0.2 cm) to produce a vulcanized rubber sheet.

<Evaluation>
The following evaluation was performed using the vulcanized rubber sheet produced as described above. The results are shown in Table 1.

(Low heat generation)
About the vulcanized rubber sheet produced as described above, in accordance with JIS K6394: 2007, using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho, under conditions of initial strain 10%, amplitude ± 2%, frequency 20 Hz, Under the condition of a temperature of 60 ° C., tan δ (60 ° C.) of the vulcanized rubber sheet was measured.
The obtained result was displayed as an index with the reciprocal of the value of Comparative Example 1 as 100.
The larger the index, the smaller the tan δ (60 ° C.), the lower the heat generation, the lower the rolling resistance when made into a tire, and the better the fuel efficiency.

(Abrasion resistance)
The abrasion resistance of the vulcanized rubber sheet produced as described above was measured in accordance with JIS K6264 using a Lambone abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.) at a temperature of 20 ° C., a load of 15 N, a slip ratio of 50%, The amount of wear was measured for 10 minutes.
The evaluation results of the wear resistance were displayed as indices with the amount of wear in each example as the reciprocal and the reciprocal of the amount of wear in Comparative Example 1 as “100”.
The larger the index, the smaller the amount of wear, and the better the wear resistance when made into a tire.

Details of each component shown in Table 1 are as follows.

As shown in Table 1, Comparative Examples 2 to 4 containing no modified diene rubber had lower abrasion resistance and room for improvement with respect to low heat build-up compared to Comparative Example 1.

On the other hand, it was confirmed that the rubber composition of the present invention can achieve a desired effect.
Comparing Examples 1 to 5 with respect to silica 1 / silica 2, Examples 1 to 4 in which silica 1 / silica 2 was 5 or less were superior to Example 5 in terms of low heat generation. In addition, Examples 2 to 5 in which the ratio of silica 1 / silica 2 was 2 or more were superior to Example 1 in abrasion resistance. From the above, it was confirmed that when the ratio of silica 1 / silica 2 is 2 or more and 5 or less, an effect of excellent balance between wear resistance and low heat build-up can be obtained.
When Examples 1 to 5 were compared with respect to the content of silica 2, it was confirmed that the higher the content of silica 2, the better the effect due to the low heat generation.

1 Bead part 2 Side wall part 3 Tire tread 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Rim cushion

Claims

A rubber component containing at least a modified diene rubber in which 0.02 to 4 mol% of the total amount of double bonds of the raw diene rubber is modified with a carboxy group;
Silica 1 having a nitrogen adsorption specific surface area of 155 m 2 / g or more;
Silica 2 having a nitrogen adsorption specific surface area of 125 m 2 / g or less;
Containing a silane coupling agent,
The content of the modified diene rubber is 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component,
The total content of the silica 1 and the silica 2 is 55 to 200 parts by mass with respect to 100 parts by mass of the rubber component;
A rubber composition for a tire tread, wherein the content of the silane coupling agent is 2 to 16% by mass of the total content.
The rubber composition according to claim 1, wherein the ratio of the content of the silica 1 to the content of the silica 2 (silica 1 / silica 2) is 2 to 10.
The rubber composition according to claim 1 or 2, wherein the modified diene rubber is produced by reacting the raw diene rubber with a nitrone compound having a carboxy group and a nitrone group.
The nitrone compound is
N-phenyl-α- (4-carboxyphenyl) nitrone,
N-phenyl-α- (3-carboxyphenyl) nitrone,
N-phenyl-α- (2-carboxyphenyl) nitrone,
N- (4-carboxyphenyl) -α-phenylnitrone,
The rubber composition according to claim 3, wherein the rubber composition is at least one selected from the group consisting of N- (3-carboxyphenyl) -α-phenylnitrone and N- (2-carboxyphenyl) -α-phenylnitrone.
The rubber composition according to claim 3 or 4, wherein a content of the nitrone compound introduced into the modified diene rubber is 0.3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component. object.
A rubber component having at least a modified diene rubber having a double bond and a carboxy group, wherein the content of the carboxy group is 0.2 to 4 mol% of the total of the double bond and the carboxy group;
Silica 1 having a nitrogen adsorption specific surface area of 155 m 2 / g or more;
Silica 2 having a nitrogen adsorption specific surface area of 125 m 2 / g or less;
Containing a silane coupling agent,
The content of the modified diene rubber is 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component,
The total content of the silica 1 and the silica 2 is 55 to 200 parts by mass with respect to 100 parts by mass of the rubber component;
A rubber composition for a tire tread, wherein the content of the silane coupling agent is 2 to 16% by mass of the total content.
A tire using the rubber composition according to any one of claims 1 to 6 for a tire tread.