JP6686362B2 - Rubber composition for tires - Google Patents

Description

  The present invention relates to a rubber composition for tires.

In recent years, a labeling (display method) system has been implemented for pneumatic tires, and it is required to achieve both wettability (braking / driving performance on wet road surface) and low rolling resistance at a higher level. This flow is not an exception for high-performance tires (UHPT) where steering stability including dry grip performance is most important, and it is necessary to improve low rolling resistance while ensuring excellent steering stability.
Conventionally, it is known that low rolling resistance and wettability are improved by changing the filler compounded into the rubber material forming the tread portion of the tire from carbon black to silica. However, the rubber compounded with silica tends to deteriorate in abrasion resistance.

On the other hand, as a conventional method related to a rubber composition for tires, for example, one described in Patent Document 1 has been proposed.
In Patent Document 1, a conjugated diene compound-non-conjugated olefin copolymer (A) having a content of a conjugated diene compound-derived portion of 40 mol% or more, a conjugated diene polymer (B), and ethylene-propylene-diene rubber. A rubber composition comprising a non-conjugated diene compound-non-conjugated olefin copolymer (C) containing is described, wherein the conjugated diene compound-non-conjugated olefin copolymer (A) is It is described that a specific compound containing antimony chloride and antimony pentachloride is used as a polymerization catalyst composition to polymerize a conjugated diene compound and a non-conjugated olefin.

International Publication No. 2012/117715 Pamphlet

  As described above, a rubber composition which is excellent in wettability, and at the same time, which can obtain a tire excellent in fuel consumption performance and wear performance has not been proposed.

  An object of the present invention is to provide a rubber composition capable of obtaining a tire having excellent wettability and at the same time excellent fuel consumption performance and wear performance.

  The inventors of the present invention have conducted extensive studies to solve the above problems, and in a specific ratio, a rubber composition containing a diene rubber having a specific glass transition temperature, silica, an antimony oxide compound, and a sulfur-containing silane coupling agent. It was found that the product achieves the above object, and completed the present invention.

  In addition, in the rubber composition described in Patent Document 1, it is described that antimony trichloride or antimony pentachloride can be used as a catalyst in the production process thereof, but the rubber composition finally obtained by production is described. Does not include antimony trichloride or antimony pentachloride as a catalyst used in the production process.

The present invention is the following (1) to (4).
(1) 80 to 180 parts by mass of silica and 1 to 50 parts by mass of an antimony oxide compound are added to 100 parts by mass of a diene rubber having an average glass transition temperature of −50 to −35 ° C., and further sulfur-containing silane coupling. A rubber composition for a tire, containing 3 to 20% by mass of the agent in a ratio to the total amount of the silica and the antimony oxide compound.
(2) The rubber composition for a tire according to (1), wherein the antimony oxide compound is fine particles having an average particle size of 20 to 60 nm.
(3) The alkylsilane having an alkyl group having 3 to 20 carbon atoms is further contained in an amount of 1 to 20% by mass with respect to the total amount of the silica and the antimony oxide compound. Rubber composition for tires.
(4) A pneumatic tire using the rubber composition according to any one of the above (1) to (3) for a tire tread.

  According to the present invention, it is possible to provide a rubber composition capable of obtaining a tire having excellent wettability and at the same time excellent fuel consumption performance and abrasion performance.

1 is a schematic partial cross-sectional view of a tire showing an example of an embodiment of a pneumatic tire of the present invention.

The present invention will be described.
The present invention contains 80 to 180 parts by mass of silica and 1 to 50 parts by mass of an antimony oxide compound with respect to 100 parts by mass of a diene rubber having an average glass transition temperature of −50 to −35 ° C., and further contains a sulfur-containing silane cup. A rubber composition for a tire, comprising a ring agent in an amount of 3 to 20% by mass with respect to the total amount of the silica and the antimony oxide compound.
Hereinafter, such a rubber composition for a tire is also referred to as a “composition of the present invention”.

<Diene rubber>
The diene rubber contained in the composition of the present invention is not particularly limited as long as it has a double bond in the main chain and has an average glass transition temperature of -50 to -35 ° C. Examples include natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene-propylene-diene co-weight. Examples include united rubber (EPDM), styrene-isoprene rubber, isoprene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber and the like.

As the diene rubber, for example, one of the above specific examples may be used alone, or two or more thereof may be used in combination.
When used alone, one having a glass transition temperature of the diene rubber of −50 to −35 ° C. is used.
In the case of using two or more kinds in combination, a glass transition temperature of each component is multiplied by mass% of each component, and the sum is -50 to -35 ° C.

  Regarding the glass transition temperature of the diene rubber, a thermogram was measured by a differential scanning calorimetry (DSC) under a heating rate condition of 20 ° C./minute, and the low temperature side baseline and the slope of the transition region (gradient straight line) were respectively measured. The temperature at the intersection of the extension lines of. Further, when the diene rubber is an oil-extended product, the glass transition temperature of the diene rubber in a state in which the oil-extended component (oil) is not contained.

  As the diene rubber, it is preferable to use natural rubber (NR) or styrene-butadiene rubber (SBR), and it is more preferable to use them in combination, because the wet performance and the low fuel consumption performance can be balanced.

  When natural rubber (NR) and styrene-butadiene rubber (SBR) are used together as the diene rubber, SBR in the diene rubber is preferably 50 to 90% by mass, and 60 to 85% by mass. Is more preferable. Within this range, the rubber composition after vulcanization will have better general physical properties.

<Silica>
The silica contained in the composition of the present invention is not particularly limited, and any conventionally known silica compounded in a rubber composition for use in a tire or the like can be used.

  Specific examples of the silica include fumed silica, calcined silica, precipitated silica, pulverized silica, fused silica and colloidal silica. These may be used alone or in combination of two or more. You may use together.

  In the present invention, the content of the silica is 80 to 180 parts by mass with respect to 100 parts by mass of the diene rubber, the wear resistance of the obtained tire is good, and the balance of fuel economy performance is good. Therefore, the amount is more preferably 95 to 150 parts by mass, further preferably 100 to 135 parts by mass.

<Antimony oxide compound>
The antimony oxide compound contained in the composition of the present invention is not particularly limited, and is preferably fine particles having an average particle diameter of 20 to 60 nm, more preferably 25 to 50 nm.

  The average particle size is determined by taking a picture of the antimony oxide compound at a magnification of 5000 times using a transmission electron microscope (TEM), selecting 500 particles arbitrarily from the obtained picture, and using a caliper to correspond to each projected area circle. The diameter is measured to obtain an integrated particle size distribution (volume basis), and the average particle diameter (median diameter) is calculated from the particle size distribution to obtain the obtained value.

Examples of the antimony oxide compound include antimony tin oxide, antimony zinc oxide, and antimony titanium oxide.
The antimony oxide compound contains antimony oxide.
The antimony oxide compound contained in the composition of the present invention is preferably an antimony oxide-tin system or an antimony oxide-indium system. Since the rubber can be made conductive by blending a tin or indium compound, the silica blended rubber can be prevented from being charged.

  In the present invention, the content of the antimony oxide compound is 1 to 50 parts by mass, more preferably 5 to 45 parts by mass, and preferably 10 to 40 parts by mass with respect to 100 parts by mass of the diene rubber. Is more preferable. When the compounding amount of the antimony oxide compound is less than 1 part by mass, the low rolling property, wet performance and wear performance of the tire are not improved, and when it exceeds 50 parts by mass, the wear performance tends to decrease.

<Sulfur-containing silane coupling agent>
The sulfur-containing silane coupling agent contained in the composition of the present invention is not particularly limited, and any conventionally known sulfur-containing silane coupling agent which is blended in the rubber composition for applications such as tires may be used. it can.

  Specific examples of the sulfur-containing silane coupling agent include 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide and triethoxysilylpropyl. -Methacrylate-monosulfide, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, bis- [3- (triethoxysilyl) -propyl] tetrasulfide, bis- [3- (trimethoxysilyl) -propyl ] Tetrasulfide, bis- [3- (triethoxysilyl) -propyl] disulfide, 3-mercaptopropyl-trimethoxysilane, 3-mercaptopropyl-triethoxysilane and the like can be mentioned, and one of these can be used alone. May be used, it may be used in combination of two or more thereof.

  In the present invention, the content of the sulfur-containing silane coupling agent is a ratio (content of the sulfur-containing silane coupling agent / (content of silica + antimony oxide compound to the total amount of the silica and the antimony oxide compound. Content) × 100) is 3 to 20% by mass, preferably 5 to 15% by mass, and more preferably 7 to 10% by mass. When the blending amount of the sulfur-containing silane coupling agent is less than 3% by mass with respect to the total amount of the silica and the antimony oxide compound, the low fuel consumption performance and wet performance of the tire, and the abrasion resistance are not improved, and the rubber is used. Processability also deteriorates. On the other hand, if the ratio with respect to the total amount of the silica and the antimony oxide compound is higher than 20% by mass, the wear performance tends to decrease.

<Alkylsilane>
The composition of the present invention further comprises a ratio of an alkylsilane having an alkyl group having 3 to 20 carbon atoms to the total amount of the silica and the antimony oxide compound (content of alkylsilane / (content of silica + antimony oxide). The content of the compound) × 100) is preferably 1 to 20% by mass.

  The alkylsilane is preferably an alkyltriethoxysilane having an alkyl group having 3 to 20 carbon atoms.

  As the alkyl group having 3 to 20 carbon atoms, methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, etc. Is mentioned. Among them, an alkyl group having 7 to 20 carbon atoms is preferable, an alkyl group having 8 to 10 carbon atoms is more preferable, and an octyl group and a nonyl group are more preferable, from the viewpoint of compatibility with a diene rubber.

  When the composition of the present invention contains the above-mentioned alkylsilane, it is possible to suppress aggregation of silica and increase in viscosity, and to manufacture a tire having excellent wet performance and low fuel consumption performance. In particular, it is possible to prevent the viscosity of the rubber composition from increasing and to improve the processability.

  The reason for this is not clear, but it is considered that the alkylsilane promotes the reaction (silanization) between silica and the silane coupling agent to improve the dispersibility of silica.

  The compounding amount of the alkylsilane having 3 to 20 carbon atoms is preferably 1 to 10% by mass, more preferably 1 to 6% by mass based on the total amount of silica and the antimony oxide compound. Not only is the dispersibility of the silica improved and the fuel economy performance improved, but a large amount of silica can be blended by suppressing the increase in viscosity of the composition of the present invention, which results in good dry and wet performance. Can be secured.

<Other ingredients>
In the composition of the present invention, in addition to the above components, an aromatic terpene resin, a filler other than silica (for example, carbon black, etc.), a silane coupling agent other than the sulfur-containing silane coupling agent, and a vulcanization agent. Alternatively, various other additives generally used in tire rubber compositions such as a cross-linking agent, a vulcanization or cross-linking accelerator, zinc oxide, a softening agent (oil), an antiaging agent, and a plasticizer may be blended. You can The amounts of these additives to be compounded can be conventional general amounts, as long as the object of the present invention is not violated.

For example, the content of the filler other than silica (for example, carbon black) is preferably 4 to 30 parts by mass, and more preferably 5 to 25 parts by mass with respect to 100 parts by mass of the diene rubber.
The content of the vulcanizing agent or the crosslinking agent is preferably 1 to 50 parts by mass, and more preferably 5 to 30 parts by mass with respect to 100 parts by mass of the diene rubber.
The content of the vulcanization accelerator or the crosslinking accelerator is preferably 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the diene rubber in the primary accelerator alone or in the blend with the secondary accelerator. It is more preferably from 0.0 to 2.5 parts by mass.
The content of zinc oxide is preferably 0.2 to 10.0 parts by mass and more preferably 0.4 to 5.0 parts by mass with respect to 100 parts by mass of the diene rubber.
The content of the softening agent (oil) is preferably 10 to 60 parts by mass and more preferably 15 to 45 parts by mass with respect to 100 parts by mass of the diene rubber.
The content of the antioxidant is preferably 0.1 to 5.0 parts by mass, and more preferably 0.2 to 4.0 parts by mass with respect to 100 parts by mass of the diene rubber.
The content of the plasticizer such as a thermoplastic resin is preferably 0 to 30 parts by mass, and more preferably 0 to 20 parts by mass with respect to 100 parts by mass of the diene rubber.

When the composition of the present invention contains an aromatic modified terpene resin, it is preferably an aromatic modified terpene resin having a softening point of 60 to 180 ° C. Here, the softening point is a Vicat softening point measured according to JIS K7206: 1999.
The content of the aromatic modified terpene resin in the composition of the present invention is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the diene rubber, and is 5 for the reason that wet grip performance and durability are more excellent. It is preferably from 30 to 30 parts by mass. When the content of the aromatic terpene resin exceeds 50 parts by mass with respect to 100 parts by mass of the diene rubber, durability and abrasion resistance may be insufficient.

[Production method]
The rubber composition of the present invention can be produced by mixing and kneading the above components.
Of the above components, components other than the vulcanization (crosslinking) agent and the vulcanization (crosslinking) accelerator are mixed and kneaded to prepare a masterbatch, and the masterbatch is subjected to the vulcanization (crosslinking) agent and the vulcanization (crosslinking) ) It is preferable that a rubber composition is produced by mixing an accelerator and kneading with an open roll or the like. In this way, a masterbatch composed of components other than the vulcanization (crosslinking) agent and the vulcanization (crosslinking) accelerator is prepared, and the vulcanization (crosslinking) agent and the vulcanization (crosslinking) accelerator are mixed in the masterbatch. When kneading, the kneading time after mixing the vulcanization (crosslinking) agent and the vulcanization (crosslinking) accelerator can be shortened, resulting in uneven vulcanization (crosslinking). It is possible to prevent deterioration of the physical properties of the composition and facilitate control of vulcanization (crosslinking).

[Pneumatic tire]
The pneumatic tire of the present invention is a pneumatic tire manufactured using the composition of the present invention described above. Among them, a pneumatic tire produced by using the composition of the present invention for a tire tread is preferable.
FIG. 1 shows a partial cross-sectional schematic view of a tire showing an example of an embodiment of the pneumatic tire of the present invention, but the pneumatic tire of the present invention is not limited to the embodiment 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.
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 extends from the tire inner side to the outer side around the bead core 5 and the bead filler 6. It is folded back and rolled up.
Further, in the tire tread 3, the belt layer 7 is arranged outside the carcass layer 4 so as to extend around the circumference of the tire.
Further, in the bead portion 1, a rim cushion 8 is arranged at a portion in contact with the rim.

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

  Since the pneumatic tire of the present invention is excellent in wet grip performance, fuel efficiency performance and wear performance, it is particularly suitable for high performance tires.

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

[Production of rubber composition]
<Standard Example, Examples 1-6, Comparative Examples 1-5>
As shown in the standard example column, the example column, and the comparative example column of Table 1, the rubber compositions according to the standard examples, Examples 1 to 6 and Comparative examples 1 to 5 are each component shown in Table 1. Was blended in the blending amount shown in Table 1 to produce.
Specifically, first, the components shown in Table 1 below, excluding sulfur and the vulcanization accelerator, were mixed for 5 minutes using a 1.7-liter closed Banbury mixer, and the temperature reached 150 ± 5 ° C. When released, it was discharged and cooled to room temperature to obtain a masterbatch. Further, sulfur and a vulcanization accelerator were mixed with the obtained master batch using the above Banbury mixer to obtain a rubber composition.

[Preparation of vulcanized rubber sheet for evaluation]
The produced rubber composition (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.

[Test evaluation method]
<Abrasion performance>
With respect to the vulcanized rubber sheet produced as described above, the abrasion loss was measured at a temperature of 20 ° C. and a slip ratio of 50% using a Lambourn abrasion 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 expressed by the following formula with the wear amount of the standard example being 100. The larger the index, the smaller the amount of wear, and the better the wear performance when used as a tire.
Abrasion performance = (amount of wear of standard example / amount of wear of sample) × 100

<Low fuel consumption performance>
According to JIS K6394: 2007, using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.), tan δ (60 ° C.) under the conditions of 10% ± 2% of elongation deformation strain rate, frequency 20 Hz, temperature 60 ° C. It was measured.
The results are shown in Table 1. The result was shown as an index with the standard example being 100. The lower this value, the better the fuel economy performance.

<WET performance>
According to JIS K6394: 2007, using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.), tan δ (0 ° C.) is measured under the conditions of 10% ± 2% elongation deformation strain rate, 20 Hz frequency, and 0 ° C. temperature. It was measured.
The results are shown in Table 1. The results were expressed as an index with tan δ (0 ° C) of the standard example as 100. The larger the index, the larger the tan δ (0 ° C), and the better the wet grip performance when used as a tire.

[Specific description of each component in the table]
Details of each component shown in the table are as follows.
・ NR: Natural rubber (Tg: -65 ° C)
-E-SBR: Styrene butadiene rubber Nipol 9548 (Tg: -42 ° C manufactured by Nippon Zeon Co., Ltd.)
-S-SBR: Styrene butadiene rubber Nipol NS522 (Nippon Zeon Tg: -31 ° C)
-BR: Butadiene rubber Nipol BR1220 (manufactured by Zeon Corporation, Tg: -105 ° C)
・ Carbon black: Show black N339 (manufactured by Cabot Japan)
Silica: ZEOSIL ^(R) 1165MP (CTAB adsorption specific surface area: 159 m ² / g, manufactured by Rhodia)
・ Zinc oxide: 3 types of zinc oxide (made by Shodo Chemical Industry Co., Ltd.)
・ Stearic acid: beads stearic acid (NOF Corporation)
Sulfur-containing silane coupling agent: bis- (3-triethoxysilylpropyl) tetrasulfide (TESPT), Evonik Si69
-Aromatically modified terpene resin: YS resin TO-125 (manufactured by Yasuhara Chemical Co., Ltd.)
Alkyltriethoxysilane: Octyltriethoxysilane KBE-3083 (manufactured by Shin-Etsu Chemical Co., Ltd.)
Antimony tin oxide 1: Nano-D average particle size manufactured by Nanotechnology Co., Ltd. = 30-40 nm
Antimony tin oxide 2: NYACOL SN902SD manufactured by Nyacol Nano Technology Co., Ltd. average particle diameter = 7 μm
・ Aroma oil: Extract No. 4S (manufactured by Showa Shell Sekiyu KK)
-Sulfur: Fine powder sulfur containing Jinhua oil (sulfur content 95.24% by mass, manufactured by Tsurumi Chemical Industry Co., Ltd.)
・ Vulcanization accelerator 1: Succinol DG (Sumitomo Chemical Co., Ltd.)
・ Vulcanization accelerator 2: NOXCELLER CZ-G (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[Explanation of test results]
<Examples 1 to 6>
In Examples 1 to 6, it was possible to improve wear performance and WET performance while suppressing deterioration of low fuel consumption performance.

<Comparative Examples 1 and 2>
In this embodiment, antimony tin oxide is not included. In this case, wear performance and fuel economy performance deteriorated.

<Comparative example 3>
This is a mode in which the amount of antimony tin oxide is large. In this case, wear performance and fuel economy performance deteriorated.

<Comparative example 4>
In this embodiment, the amount of antimony tin oxide is small. In this case, the wear performance deteriorated.

<Comparative Example 5>
This is a mode in which the average glass transition temperature of the diene rubber is low. In this case, the WET performance deteriorated.

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 (4)

80 to 180 parts by mass of silica, 1 to 50 parts by mass of an antimony oxide compound, and 100% by mass of a diene rubber having an average glass transition temperature of −50 to −35 ° C., and a sulfur-containing silane coupling agent, the silica and the ratio of 3 to 20 wt% observed including in the total amount of said antimony oxide compound, a further alkylsilane having an alkyl group having 3 to 20 carbon atoms, the ratio of the total amount of the said silica antimony oxide compound A rubber composition for tires containing 1 to 20% by mass . 80 to 180 parts by mass of silica and 1 to 50 parts by mass of an antimony oxide compound which is a fine particle having an average particle size of 20 to 60 nm with respect to 100 parts by mass of a diene rubber having an average glass transition temperature of -50 to -35 ° C. A rubber composition for a tire, which further comprises a sulfur-containing silane coupling agent in an amount of 3 to 20% by mass with respect to the total amount of the silica and the antimony oxide compound. The tire rubber composition according to claim 2 , further comprising an alkylsilane having an alkyl group having 3 to 20 carbon atoms in an amount of 1 to 20% by mass based on the total amount of the silica and the antimony oxide compound.   A pneumatic tire using the rubber composition for a tire according to claim 1 as a tire tread.

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