JP6807653B2 - Rubber composition for tires - Google Patents

Description

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

In recent years, it has been required to reduce the rolling resistance of tires from the viewpoint of vehicle fuel efficiency. On the other hand, there is known a method of reducing the rolling resistance of a tire and improving the fuel efficiency of the tire by blending silica with a rubber component constituting the tire to reduce the hysteresis loss (tan δ).
However, since silica has a low affinity with the rubber component and has high cohesiveness between silicas, even if silica is simply mixed with the rubber component, the silica does not disperse, and the effect of reducing rolling resistance is sufficiently obtained. There was a problem that it could not be done. In addition, there is also a problem that workability deteriorates due to aggregation of silicas.

Under such circumstances, for example, Patent Document 1 discloses a technique for improving workability and low rolling resistance when a tire is formed by blending an amphoteric surfactant in a rubber composition for a tire.

Japanese Unexamined Patent Publication No. 2013-112743

On the other hand, when the present inventors examined a rubber composition for a tire containing an amphoteric surfactant based on Patent Document 1, it was found that its workability and fuel efficiency performance when made into a tire were not always sufficient. It was revealed. It was also clarified that the wear resistance of tires needs to be further improved.

Therefore, in view of the above circumstances, it is an object of the present invention to provide a rubber composition having excellent workability, low fuel consumption performance and wear resistance when made into a tire.

As a result of diligent studies on the above problems, the present inventors have found that the above problems can be solved by blending a specific cationic surfactant which is a quaternary ammonium salt having an amide bond, and have reached the present invention.
That is, the present inventor has found that the above problem can be solved by the following configuration.

(1) Contains diene-based rubber, silica, and a cationic surfactant,
The CTAB adsorption specific surface area of the silica is 115-300 m ² / g.
The above-mentioned cationic surfactant is a quaternary ammonium salt having an amide bond.
The content of the silica is 50 to 200 parts by mass with respect to 100 parts by mass of the diene rubber.
A rubber composition for a tire, wherein the content of the cationic surfactant is 0.05 to 10 parts by mass with respect to 100 parts by mass of the diene rubber.
(2) The rubber composition for a tire according to (1) above, wherein the cationic surfactant has two or more amide bonds.
(3) The rubber composition for a tire according to the above (1) or (2), wherein the cationic surfactant is a compound represented by the formula (1) described later.
(4) The rubber composition for a tire according to any one of (1) to (3) above, which further contains a glycerin partial fatty acid ester.
(5) The rubber composition for a tire according to (4) above, wherein the glycerin partial fatty acid ester is an ester of glycerin and a fatty acid having 14 to 24 carbon atoms.
(6) The above-mentioned (4) or (5), wherein the ratio of the content of the cationic surfactant to the content of the glycerin partial fatty acid ester is 0.1 to 1.0 by mass ratio. Rubber composition for tires.
(7) The rubber composition for a tire according to any one of (1) to (3) above, which further contains a fatty acid metal salt.
(8) The rubber composition for a tire according to (7) above, wherein the fatty acid metal salt is a fatty acid magnesium salt.
(9) The rubber composition for a tire according to (7) or (8) above, wherein the fatty acid metal salt is a metal salt of a fatty acid having 8 to 24 carbon atoms.
(10) Any of the above (7) to (9), wherein the ratio of the content of the cationic surfactant to the content of the fatty acid metal salt is 0.1 to 1.0 by mass ratio. The described rubber composition for tires.
(11) The rubber composition for a tire according to any one of (1) to (10) above, wherein the CTAB adsorption specific surface area of the silica is 180 to 300 m ² / g.

As shown below, according to the present invention, it is possible to provide a rubber composition having excellent workability, low fuel consumption performance and wear resistance when made into a tire.

It is a partial cross-sectional schematic diagram which shows an example of embodiment of the tire of this invention.

The rubber composition for a tire of the present invention and the tire of the present invention will be described below.
The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

[Rubber composition for tires]
The rubber composition for tires of the present invention (hereinafter, also referred to as "composition of the present invention") contains a diene-based rubber, silica, and a cationic surfactant.
Here, the CTAB adsorption specific surface area of the silica is 115 to 300 m ² / g. The cationic surfactant is a quaternary ammonium salt having an amide bond. The content of the silica is 50 to 200 parts by mass with respect to 100 parts by mass of the diene rubber, and the content of the cationic surfactant is 0.05 with respect to 100 parts by mass of the diene rubber. It is 10 parts by mass.
Since the composition of the present invention has such a structure, it is considered that the above-mentioned effects can be obtained. The reason is not clear, but it is thought to be as follows.

The composition of the present invention contains a quaternary ammonium salt having an amide bond as a cationic surfactant. Here, the quaternary ammonium ion in the cationic surfactant interacts with the hydroxyl group on the surface of the silica to suppress the aggregation of the silicas, and further, the amide bond in the cationic surfactant causes the aggregation of the surfactants. It is thought to suppress it. As a result, in the composition of the present invention, the dispersibility of silica is extremely high, and it is considered that the composition exhibits excellent processability. Further, it is considered that the dispersibility of silica is extremely high also in the tire obtained from the composition of the present invention, and the effect of reducing hysteresis loss by silica is sufficiently exhibited. Furthermore, it is considered that the abrasion resistance is also excellent because the aggregation of silica is small.
When an amphoteric surfactant is used instead of the cationic surfactant, it is considered that the above-mentioned effects are not sufficiently exhibited due to the aggregation of the amphoteric surfactants.
However, the above mechanism is an estimation, and even if it is other than the mechanism, it is within the scope of the present invention.

Hereinafter, each component contained in the composition of the present invention will be described.

<Diene rubber>
The diene-based rubber contained in the composition of the present invention is not particularly limited, and specific examples thereof include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), and aromatic vinyl-conjugated diene copolymer. Examples thereof include coalesced rubber, acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). As the diene rubber, one kind of diene rubber may be used alone, or two or more kinds of diene rubber may be used in combination.

As the diene-based rubber, it is preferable to use an aromatic vinyl-conjugated diene copolymer rubber because the obtained tire has excellent rigidity, and a butadiene rubber (BR) is used in combination with the aromatic vinyl-conjugated diene copolymer. It is more preferable to do so.
Examples of the aromatic vinyl-conjugated diene copolymer rubber include styrene butadiene rubber (SBR) and styrene isoprene copolymer rubber. Of these, styrene-butadiene rubber (SBR) is preferable because the obtained tire has excellent rigidity.

The aromatic vinyl content (for example, styrene content) of the aromatic vinyl-conjugated diene copolymer is preferably 20 to 45% by mass, preferably 23 to 42% by mass, for the reason that the effect of the present invention is more excellent. More preferably.
Further, the amount of vinyl bond in the conjugated diene of the aromatic vinyl-conjugated diene copolymer is preferably 10 to 50%, preferably 25 to 48%, for the reason that the effect of the present invention is more excellent. More preferred. Here, the amount of vinyl bond refers to the ratio of 1,2-vinyl bond among cis-1,4-bond, trans-1,4-bond and 1,2-vinyl bond, which are the bonding modes of conjugated diene. Say.

The method for producing the aromatic vinyl-conjugated diene copolymer is not particularly limited, and the aromatic vinyl-conjugated diene copolymer can be produced by a conventionally known method.
Further, the aromatic vinyl and the conjugated diene as the monomer used in producing the aromatic vinyl-conjugated diene copolymer are not particularly limited.
Here, examples of the conjugated diene monomer include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and 2-chloro-1. , 3-butadiene, 1,3-pentadiene and the like.
On the other hand, examples of the aromatic vinyl monomer include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, and 2,4-diisopropylstyrene. Examples thereof include 4-tert-butylstyrene, divinylbenzene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethylaminoethylstyrene and vinylpyridine.

When the aromatic vinyl-conjugated diene copolymer is used, the content is preferably 50 to 100% by mass and 55 to 95% by mass of the diene rubber because the obtained tire has excellent rigidity. More preferably, it is more preferably 60 to 90% by mass.
Further, when the butadiene rubber (BR) is used in combination with the aromatic vinyl-conjugated diene copolymer, the content of the butadiene rubber (BR) is higher than that of the diene rubber because the effect of the present invention is more excellent. It is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, and even more preferably 20 to 40% by mass.

The weight average molecular weight of the diene-based rubber (particularly, the aromatic vinyl-conjugated diene copolymer) is not particularly limited, but is preferably 100,000 to 1,500,000 from the viewpoint of handling, 600, More preferably, it is 000 to 1,300,000. The weight average molecular weight (Mw) of the diene-based rubber shall be measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent in terms of standard polystyrene.

The Tg (glass transition temperature) of the diene-based rubber (particularly, the aromatic vinyl-conjugated diene copolymer) is not particularly limited, but it should be −70 to −10 ° C. for the reason that the effect of the present invention is more excellent. Is preferable, and the temperature is more preferably -40 to -20 ° C.

<Silica>
The silica contained in the composition of the present invention is not particularly limited as long as it is silica having a CTAB (cetyltrimethylammonium bromide) adsorption specific surface area of 115 to 300 m ² / g, and is blended in a rubber composition for applications such as tires. Any conventionally known silica can be used.
Examples of the silica include wet silica, dry silica, fumed silica, and diatomaceous earth. As the silica, one kind of silica may be used alone, or two or more kinds of silica may be used in combination.

The CTAB adsorption specific surface area is preferably 180 to 300 m ² / g because the effect of the present invention is more excellent.

In the present specification, the CTAB adsorption specific surface area is a value obtained by measuring the amount of CTAB adsorbed on the silica surface according to JIS K6217-3: 2001 "Part 3: How to obtain the specific surface area-CTAB adsorption method".

In the composition of the present invention, the content of silica is 50 to 200 parts by mass with respect to 100 parts by mass of the diene rubber. Among them, 70 to 150 parts by mass is preferable because the effect of the present invention is more excellent.

<Cationic surfactant>
The cationic surfactant (cationic surfactant) contained in the composition of the present invention has an amide bond (-NR-CO-: where R represents a hydrogen atom or a substituent (preferably a hydrocarbon group)). It is a quaternary ammonium salt having (hereinafter, also referred to as "specific cationic surfactant"). The quaternary ammonium salt is preferably a salt of a quaternary ammonium ion and a halide ion (fluoride ion, chloride ion, bromide ion, iodide ion, etc.).
In the present specification, the cationic surfactant is a surfactant having only a cationic (cationic) dissociation group as a dissociation group, and a cationic (cationic) dissociation group and an anion as a dissociation group. So-called amphoteric surfactants having both sex (anionic) dissociative groups are not included.

The number of amide bonds contained in the specific cationic surfactant is preferably 2 or more and 4 or less from the viewpoint of silica adsorption and silica dispersibility.

Preferable embodiments of the specific cationic surfactant include, for example, a compound represented by the following formula (1).

In the formula (1), R ¹ represents a hydrocarbon group having 1 to 8 carbon atoms or a group represented by the following formula (2), R ² represents an alkylene group, R ³ represents an acyl group, and R ⁴ Represents a methyl group, an ethyl group or a benzyl group, X represents a halogen atom, and m represents a number 1 to 3.

In formula (2), R ⁵ represents a hydrogen atom or an acyl group, R ⁶ represents a hydrogen atom or a methyl group, and n represents a number 1 to 3.

In the formula (1), R ¹ represents a hydrocarbon group having 1 to 8 carbon atoms or a group represented by the above formula (2). The hydrocarbon group having 1 to 8 carbon atoms includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secondary butyl group, a t-butyl group, a pentyl group, an isopentyl group, and a secondary pentyl group. , T-pentyl group, hexyl group, secondary hexyl group, heptyl group, secondary heptyl group, octyl group, secondary octyl group, 2-methylpentyl group, 2-ethylhexyl group, vinyl group, allyl group, propenyl group, Examples thereof include a butenyl group, an isobutenyl group, a pentanyl group, an isopentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a cyclohexyl group, a phenyl group, a methylphenyl group and a benzyl group.

In formula (2), R ⁵ represents a hydrogen atom or an acyl group. In the present invention, the acyl group refers to a residue obtained by removing OH from a monovalent carboxylic acid. Examples of such carboxylic acids include acetic acid, propionic acid, butanoic acid, pentanoic acid, isopentanoic acid, caproic acid (hexanoic acid), heptanic acid, caproic acid (octanoic acid), nonanoic acid, capric acid (decanoic acid), and laurin. Saturated fatty acids such as acid (undecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), stearic acid (octadecanoic acid), arachidic acid (eicosanoic acid), behenic acid (docosic acid), tetracosanoic acid, hexacosanoic acid, etc. Unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, ellaic acid, and erucic acid; hydroxy fatty acids such as ricinoleic acid and hydroxystearic acid can be mentioned.

In formula (2), R ⁶ represents a hydrogen atom or a methyl group, and n represents a number 1-3 (preferably an integer 1-3). R ⁶ is preferably a hydrogen atom, and n is preferably 1 because it is more excellent in adsorptivity to silica.

In the formula (1), R ¹ is preferably a methyl group or an ethyl group, and more preferably a methyl group, from the viewpoint of adsorptivity to silica.

In formula (1), R ² represents an alkylene group. Examples of the alkylene group a methylene group, an ethylene group, a propylene group, a hexamethylene group, since octamethylene group and the like, excellent by adsorption onto silica, industrial availability of raw materials is easy, R ² is ethylene A group and a propylene group are preferable.

In the formula (1), R ³ represents an acyl group, and examples of the carboxylic acid corresponding to the acyl group include the carboxylic acid exemplified by R ⁵ in the formula (2). From the viewpoint of adsorptivity to silica and dispersibility of silica, fatty acids having 8 to 22 carbon atoms are preferable, and fatty acids having 10 to 18 carbon atoms are more preferable. R ⁴ represents a methyl group, an ethyl group or a benzyl group, and a methyl group is preferable from the viewpoint of adsorptivity to silica. X represents a halogen atom, and examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom. As X, a chlorine atom is preferable from the viewpoint of adsorptivity to silica. m represents a number of 1 to 3 (preferably an integer of 1 to 3), and m is preferably 2 from the viewpoint of adsorptivity to silica and dispersibility of silica. When a plurality of acyl groups are present in the compound represented by the formula (1), they may be the same group or different groups.

In the composition of the present invention, the content of the specific cationic surfactant is 0.05 to 10 parts by mass with respect to 100 parts by mass of the above-mentioned diene rubber. If the content of the specific cationic surfactant is less than 0.05 parts by mass, the dispersibility of silica becomes insufficient, and if it exceeds 10 parts by mass, the durability of the rubber is lowered. The content of the specific cationic surfactant with respect to 100 parts by mass of the diene rubber is preferably 0.1 to 5 parts by mass, and more preferably 1 to 3 parts by mass. As the specific cationic surfactant, one type may be used alone, or two or more types may be used in combination.

<Arbitrary ingredient>
(Glycerin partial fatty acid ester)
The composition of the present invention preferably contains a glycerin partial fatty acid ester together with the above-mentioned specific cationic surfactant. Since the glycerin partial fatty acid ester improves the dispersibility of the specific cationic surfactant, as a result, the dispersibility of silica is further enhanced, and the above-mentioned effect of the present invention becomes more excellent. In the present invention, the partial fatty acid ester means a compound in which a part of the hydroxyl groups of the polyhydric alcohol is esterified with a fatty acid, and the glycerin partial fatty acid ester includes a glycerin monofatty acid ester and a glycerin difatty acid ester. ..

The fatty acid of the glycerin partial fatty acid esters, include carboxylic acids exemplified by R ⁵ of formula (2), from the viewpoint of dispersibility of the silica, preferably saturated fatty acids from 14 to 24 carbon atoms, saturated 16-22 Fatty acids are more preferred, and stearic acid is most preferred. One type of fatty acid may be used alone or two or more types may be used in combination, but when there are two or more types of fatty acids, one of them is preferably stearic acid.

The glycerin partial fatty acid ester is preferably a glycerin monofatty acid ester from the viewpoint of silica dispersibility, and in the case of a mixture of the glycerin monofatty acid ester and the glycerin difatty acid ester, the content of the glycerin monofatty acid ester is at least 50% by mass. Is preferable.

When the composition of the present invention contains a glycerin partial fatty acid ester, if the content of the glycerin partial fatty acid ester is too small, the effect of improving the dispersibility of silica cannot be obtained, and if it is too large, the physical properties of rubber. May have an adverse effect on. Therefore, the ratio of the content of the above-mentioned specific cationic surfactant to the content of the glycerin partial fatty acid ester (specific cationic surfactant / glycerin partial fatty acid ester) is 0.01 to 10 by mass ratio. Is preferable, 0.1 to 1.0 is more preferable, and 0.2 to 0.5 is further preferable.
The content of the glycerin partial fatty acid ester is preferably 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the diene rubber described above. The total content of the above-mentioned specific cationic surfactant and the glycerin partial fatty acid ester is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the above-mentioned diene rubber. One type of glycerin partial fatty acid ester may be used alone, or two or more types may be used in combination.

(Fatty acid metal salt)
The composition of the present invention preferably contains a fatty acid metal salt together with the above-mentioned specific cationic surfactant. Since the fatty acid metal salt improves the dispersibility of the specific cationic surfactant, as a result, the dispersibility of silica is further enhanced, and the above-mentioned effect of the present invention becomes more excellent.

The fatty acid metal salt is a salt of a fatty acid and a metal.
The fatty acid of the fatty acid metal salt, include carboxylic acids exemplified by R ⁵ of formula (2), from the viewpoint of the dispersibility of the silica, saturated fatty acids having 8 to 24 carbon atoms are preferred, 10 to 22 carbon atoms Saturated fatty acids are more preferred, saturated fatty acids with 16 to 22 carbon atoms are even more preferred, and behenic acid is most preferred. One type of fatty acid may be used alone, or two or more types may be used in combination.
Examples of the metal of the fatty acid metal salt include alkali metals, alkaline earth metals, transition metals (metals of groups 3 to 11), aluminum, germanium, tin, antimony, etc. Among them, alkali metals (lithium, potassium, (Sodium, etc.), alkaline earth metals (berylium, magnesium, calcium, strontium, barium, etc.), etc., and from the viewpoint of silica dispersibility, alkali metals and alkaline earth metals are more preferable, and alkaline earth metals are further preferable. Preferably, magnesium is most preferred.
Specific examples of preferable fatty acid metal salts include potassium stearate, zinc stearate, magnesium stearate, magnesium oleate, magnesium palmitate, magnesium myristate, magnesium laurate, magnesium linoleate, magnesium behenate and the like.

When the composition of the present invention contains a fatty acid metal salt, if the content of the fatty acid metal salt is too small, the effect of improving the dispersibility of silica cannot be obtained, and if it is too large, the physical properties of rubber are adversely affected. May appear. Therefore, the ratio of the content of the above-mentioned specific cationic surfactant to the content of the fatty acid metal salt (specific cationic surfactant / fatty acid metal salt) is preferably 0.01 to 10 in terms of mass ratio. , 0.1 to 1.0, more preferably 0.2 to 0.5. The content of the fatty acid metal salt is preferably 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the above-mentioned diene rubber. The total content of the above-mentioned specific cationic surfactant and the fatty acid metal salt is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the above-mentioned diene rubber. One type of fatty acid metal salt may be used alone, or two or more types may be used in combination.

The composition of the present invention preferably contains both a glycerin partial acid ester and a fatty acid metal salt together with the above-mentioned specific cationic surfactant, for the reason that the above-mentioned effect of the present invention is further excellent.

(Other additives)
If necessary, the composition of the present invention may further contain additives as long as the effects and purposes are not impaired.
Examples of the above-mentioned additives include fillers other than silica (for example, carbon black), zinc oxide (zinc oxide), stearic acid, antiaging agents, processing aids, process oils, aroma oils, liquid polymers, and terpene resins. Examples thereof include various additives generally used in rubber compositions such as thermosetting resins, vulcanizing agents (for example, sulfur), and vulcanization accelerators.

<Method of preparing rubber composition for tires>
The method for preparing the composition of the present invention is not particularly limited, and as a specific example thereof, each of the above-mentioned components is kneaded using a known method or device (for example, Banbury mixer, kneader, roll, etc.). The method etc. can be mentioned. When the composition of the present invention contains sulfur or a vulcanization accelerator, components other than sulfur and the vulcanization accelerator are first mixed at a high temperature (preferably 140 to 160 ° C.), cooled, and then sulfur or It is preferable to mix the vulcanization accelerator.
In addition, the composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[tire]
The tire of the present invention is a tire manufactured by using the composition of the present invention described above. Of these, a tire using the composition of the present invention for a tire tread is preferable.
FIG. 1 shows a schematic partial cross-sectional view of a tire showing an example of an embodiment of the tire of the present invention, but the tire of the present invention is not limited to the aspect shown in FIG.

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 portion.
Further, a carcass layer 4 in which a fiber cord is embedded is mounted between the pair of left and right bead portions 1, and the end portion of the carcass layer 4 is placed around the bead core 5 and the bead filler 6 from the inside to the outside of the tire. It is folded back and rolled up.
Further, in the tire tread portion 3, a belt layer 7 is arranged on the outside of the carcass layer 4 over one circumference of the tire.
Further, in the bead portion 1, the rim cushion 8 is arranged at a portion in contact with the rim.
The tire tread portion 3 is formed by the composition of the present invention described above.

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

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

<Preparation of rubber composition for tires>
The components shown in Table 1 below were blended in the proportions (parts by mass) shown in the same table.
Specifically, first, among the components shown in the same table, the components excluding sulfur and the vulcanization accelerator were mixed for 5 minutes using a 1.7 liter sealed Banbury mixer. The temperature at the time of release was 152 ° C., and the mixture was cooled to room temperature to obtain a masterbatch. Further, using the above-mentioned Bunbury mixer, sulfur and a vulcanization accelerator were mixed with the obtained masterbatch for 3 minutes and released at 110 ° C. to obtain a rubber composition for a tire.

<Evaluation>
The obtained rubber composition for tires was evaluated as follows.

(Workability)
Mooney viscosity (ML _{1 + 4} ) at 100 ° C. was measured according to JIS K6300-1: 2013. The reciprocal of Mooney viscosity is shown in Table 1. The results were expressed as an index with the reciprocal of the Mooney viscosity of Comparative Example 1 as 100. The larger the index, the lower the viscosity and the better the workability.

(Fuel efficiency performance)
The obtained rubber composition for tires (unvulcanized) was press-vulcanized in a mold (15 cm × 15 cm × 0.2 cm) at 160 ° C. for 20 minutes to prepare a vulcanized rubber sheet.
The produced vulcanized rubber sheet was subjected to a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K6394: 2007 under the conditions of a stretch deformation strain rate of 10% ± 2%, a frequency of 20 Hz, and a temperature of 60 ° C. , Tan δ (60 ° C.) was measured.
The reciprocal of tan δ (60 ° C.) is shown in Table 1. The results were expressed as an index with the reciprocal of tan δ (60 ° C.) of Comparative Example 1 as 100. The larger the index, the smaller the tan δ (60 ° C.), and the better the fuel efficiency performance.

(Abrasion resistance)
The vulcanized rubber sheet prepared as described above is subjected to wear reduction under the conditions of a temperature of 20 ° C. and a slip ratio of 50% using a Lambourn wear tester (manufactured by Iwamoto Seisakusho) in accordance with JIS K6264-1, 2: 2005. It was measured.
The results are shown in Table 1. The results are indexed by the following equation, with the wear amount of Comparative Example 1 as 100. The larger the index, the smaller the amount of wear and the better the wear resistance.
Abrasion resistance = (Abrasion amount of Comparative Example 1 / Abrasion amount of sample) × 100

The details of each component in Table 1 are as follows.
-SBR: Buna VSL 5025-2 HM manufactured by LANXESS, Tg (glass transition temperature): -27 ° C., styrene content: 25% by mass
・ BR: Nipol BR 1220 manufactured by Zeon Corporation
・ Carbon Black: Tokai Carbon Co., Ltd. Seest 7HM
-Silica 1: Solvay Zeosil 1165MP
-Silica 2: Zeosil 1205MP manufactured by Solvay
-Silane coupling agent: KBE-846 (bis (3- (triethoxysilyl) propyl) tetrasulfide) manufactured by Shin-Etsu Chemical Co., Ltd.
Cationic surfactants: following structure (where, R ³ represents an acyl group derived from decanoic acid (capric acid))

-Amphoteric tenside: Anhitor 20AB manufactured by Kao Co., Ltd., cocamidopropyl betaine-glycerin partial fatty acid ester: glycerin monostearic acid ester / glycerin distearate ester = 2/1 (mass ratio)
-Fatty acid metal salt 1: potassium stearate (potassium content 12.5% by mass)
-Fatty acid metal salt 2: Magnesium stearate (magnesium content 4.5% by mass)
-Fatty acid metal salt 3: Magnesium behenate (magnesium content 3.4% by mass)
・ Aroma oil: H & R aroma oil ・ Zinc flower: Zinc oxide 3 types manufactured by Shodo Chemical Co., Ltd. ・ Stearic acid: Industrial stearic acid N manufactured by Chiba Fatty Acid Co., Ltd.
・ Vulcanization accelerator: Noxera CZ-G manufactured by Ouchi Shinko Co., Ltd.
・ Sulfur: Oil-treated sulfur manufactured by Hosoi Chemical Co., Ltd.

Examples 1 to 10 containing the specific cationic surfactant showed excellent processability, fuel efficiency and abrasion resistance.
Comparison of Examples 1 and 3 to 4 and 6 to 9 (contrast of the embodiment in which the CTAB adsorption specific surface area of silica is 160 m ² / g) and comparison of Examples 2 and 5 and 10 (CTAB adsorption of silica). Examples 3 to 4 and 6 to 9 and Examples 5 and 10 further containing a glycerin partial fatty acid ester or a fatty acid metal salt from the aspect of the specific surface area of 200 m ² / g) are more excellent processed. It showed good properties, low fuel consumption performance and wear resistance. Among them, Examples 6 to 9 and 10 containing a fatty acid metal salt showed further excellent processability and fuel efficiency.
In addition, the contrast of Examples 1 and 2 (contrast of the embodiment containing neither the glycerin partial fatty acid ester nor the fatty acid metal salt), the contrast of Examples 3 to 5 (contrast of the embodiment containing the glycerin partial fatty acid ester), and From the comparison of Examples 6 to 10 (contrast of the aspect containing the fatty acid metal salt), Examples 2, 5 and 10 in which the CTAB adsorption specific surface area of silica is 180 to 300 m ² / g have better wear resistance. showed that.
Further, from the comparison between Examples 3 and 4 (contrast of the embodiment in which the CTAB adsorption specific surface area of silica is 160 m ² / g and the glycerin partial fatty acid ester is contained), the cationic interface with respect to the content of the glycerin partial fatty acid ester. Example 4 in which the ratio of the content of the activator was 0.1 to 1.0 by mass showed better processability, low fuel consumption performance and abrasion resistance.
Further, from the comparison of Examples 6 to 9 (contrast of the embodiment in which the CTAB adsorption specific surface area of silica is 160 m ² / g and the fatty acid metal salt is contained), the cationic surfactant with respect to the content of the fatty acid metal salt Examples 7 to 9 in which the content ratio was 0.1 to 1.0 by mass showed better workability and abrasion resistance.
Further, from the comparison between Examples 7 and 8 (contrast in the embodiment in which the metal stearic acid salt is contained and the ratio of the content of the cationic surfactant to the content of the metal stearic acid salt is 0.25). Example 8 in which the fatty acid metal salt contained was a magnesium salt of a fatty acid showed better processability.
Further, from the comparison between Examples 8 and 9 (contrast of the aspect in which the CTAB adsorption specific surface area of silica is 160 m ² / g and the fatty acid magnesium salt is contained), the fatty acid metal salt contained has 20 or more carbon atoms. Example 9, which is a metal salt of the fatty acid of the above, showed better processability, low fuel consumption performance and abrasion resistance.

On the other hand, Comparative Examples 1 and 2 containing no specific cationic surfactant had insufficient processability. In Comparative Example 1, the fuel efficiency performance was also insufficient.
Further, Comparative Example 3 in which the specific cationic surfactant was contained but the content of the specific cationic surfactant exceeded 10 parts by mass with respect to 100 parts by mass of the diene rubber was also insufficient in processability.
Further, Comparative Example 4 containing an amphoteric surfactant which is a quaternary ammonium salt having an amide bond instead of the specific cationic surfactant had insufficient wear resistance.

1 bead part 2 sidewall part 3 tire tread part 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 rim cushion

Claims (11)

Contains diene rubber, silica, and cationic surfactant,
The CTAB adsorption specific surface area of the silica is 115-300 m ² / g.
The cationic surfactant is a quaternary ammonium salt having an amide bond.
The content of the silica is 50 to 200 parts by mass with respect to 100 parts by mass of the diene rubber.
A rubber composition for a tire, wherein the content of the cationic surfactant is 0.05 to 10 parts by mass with respect to 100 parts by mass of the diene rubber. The rubber composition for a tire according to claim 1, wherein the cationic surfactant has two or more amide bonds. The rubber composition for a tire according to claim 1 or 2, wherein the cationic surfactant is a compound represented by the following formula (1).
In the formula (1), R ¹ represents a hydrocarbon group having 1 to 8 carbon atoms or a group represented by the following formula (2), R ² represents an alkylene group, R ³ represents an acyl group, and R ⁴ Represents a methyl group, an ethyl group or a benzyl group, X represents a halogen atom, and m represents a number 1 to 3.

In formula (2), R ⁵ represents a hydrogen atom or an acyl group, R ⁶ represents a hydrogen atom or a methyl group, and n represents a number 1 to 3. The rubber composition for a tire according to any one of claims 1 to 3, further comprising a glycerin partial fatty acid ester. The rubber composition for a tire according to claim 4, wherein the glycerin partial fatty acid ester is an ester of glycerin and a fatty acid having 14 to 24 carbon atoms. The rubber composition for a tire according to claim 4 or 5, wherein the ratio of the content of the cationic surfactant to the content of the partial fatty acid ester of glycerin is 0.1 to 1.0 by mass ratio. The rubber composition for a tire according to any one of claims 1 to 3, further comprising a fatty acid metal salt. The rubber composition for a tire according to claim 7, wherein the fatty acid metal salt is a fatty acid magnesium salt. The rubber composition for a tire according to claim 7 or 8, wherein the fatty acid metal salt is a metal salt of a fatty acid having 8 to 24 carbon atoms. The tire according to any one of claims 7 to 9, wherein the ratio of the content of the cationic surfactant to the content of the fatty acid metal salt is 0.1 to 1.0 by mass ratio. Rubber composition. The rubber composition for a tire according to any one of claims 1 to 10, wherein the silica has a CTAB adsorption specific surface area of 180 to 300 m ² / g.