JP6657759B2 - Rubber composition for tire - Google Patents

Description

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

In recent years, a labeling (display method) system has been applied to pneumatic tires, and there is a demand for achieving a higher level of both wetness (braking / driving performance on wet road surfaces) and low rolling resistance.
Conventionally, it has been known that low rolling resistance and wettability are improved by changing a filler to be mixed into a rubber material constituting a tread portion of a tire from carbon black to silica. However, the silica-compounded rubber tends to have poor wear performance.

On the other hand, as conventional methods related to rubber compositions for tires, for example, those described in Patent Documents 1 and 2 have been proposed.
Patent Document 1 discloses 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-based polymer (B), and an ethylene-propylene-diene rubber. A rubber composition comprising a non-conjugated diene compound and a non-conjugated olefin copolymer (C) containing a conjugated diene compound and a non-conjugated olefin copolymer (C). It describes that a specific compound containing is used as a polymerization catalyst composition to polymerize a conjugated diene compound and a non-conjugated olefin.

  In Patent Document 2, pMC (percent Modern Carbon) obtained by polymerizing a monomer component derived from biomass and measured according to ASTM D6866-10 is 1% or more, and glass transition temperature (Tg) is -120 to -80. A rubber composition for a tire containing a biomass-derived rubber at a temperature of 0 ° C. is described, and it is described that a biomass-derived monomer component can be obtained using cerium oxide as a catalyst.

WO 2012/117715 pamphlet JP 2014-231605 A

  As described above, a rubber composition capable of obtaining a tire excellent in wettability and at the same time excellent in fuel efficiency 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 efficiency and wear performance.

  The present inventors have conducted intensive studies to solve the above problems, and at a specific ratio, a rubber composition containing a diene rubber having a specific glass transition temperature, silica, cerium oxide, and a sulfur-containing silane coupling agent. However, they have found that the above object is achieved, and have completed the present invention.

  In the rubber compositions described in Patent Documents 1 and 2, it is described that cerium or cerium oxide can be used as a catalyst in the production process. Does not include cerium or cerium oxide as a catalyst used in the production process.

The present invention is the following (1) to (3).
(1) With respect to 100 parts by mass of a diene rubber having an average glass transition temperature of -50 to -20 ° C, it contains 10 to 90 parts by mass of silica and 1 to 50 parts by mass of cerium oxide, and further contains a sulfur-containing silane coupling agent. And a rubber composition for a tire, comprising 3 to 20% by mass of the total amount of the silica and the cerium oxide.
(2) The rubber composition for a tire according to the above (1), wherein the cerium oxide is fine particles having an average particle diameter of 20 to 60 nm.
(3) A pneumatic tire using the rubber composition according to (1) or (2) for a tire tread.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which can obtain the tire which is excellent in wettability, at the same time, also excellent in fuel efficiency performance and abrasion performance can be provided.

It is a partial section schematic diagram 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 includes 10 to 80 parts by mass of silica and 1 to 50 parts by mass of cerium oxide, based on 100 parts by mass of a diene rubber having an average glass transition temperature of -50 to -20 ° C, and further contains a sulfur-containing silane coupling. A rubber composition for a tire, comprising an agent in an amount of 3 to 20% by mass relative to the total amount of the silica and the cerium oxide.
Hereinafter, such a rubber composition for a tire is also referred to as “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 -20 ° C. Examples include natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and ethylene-propylene-diene copolymer. Combined 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, a diene rubber having a glass transition temperature of −50 to −20 ° C. is used.
When two or more kinds are used in combination, those having a value obtained by multiplying the glass transition temperature of each component by the mass% of each component and adding the resulting values are −50 to −20 ° C.

  The glass transition temperature of the diene rubber is measured by a differential scanning calorimetry (DSC) at a heating rate of 20 ° C./min, and a thermogram is measured. Is the temperature at the intersection of the extension lines. When the diene-based rubber is an oil-extended product, the glass transition temperature of the diene-based rubber in a state in which the oil-extended component (oil) is not included is used.

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

  When styrene-butadiene rubber (SBR) and butadiene rubber (BR) are used in combination as the diene rubber, the SBR is preferably 50 to 100% by mass, more preferably 70 to 95% by mass in the diene rubber. Is more preferred. Within this range, the general physical properties of the vulcanized rubber composition will be better.

<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 applications such as tires can be used.

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

  In the present invention, the content of the silica is 10 to 80 parts by mass with respect to 100 parts by mass of the diene rubber, the resulting tire has good wear resistance, and a good balance of fuel economy performance is obtained. Therefore, the amount is more preferably 20 to 70 parts by mass, and still more preferably 30 to 60 parts by mass.

<Cerium oxide>
Cerium oxide 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 20 to 50 nm.

  The average particle diameter was determined by taking a photograph of cerium oxide at a magnification of 5000 using a transmission electron microscope (TEM), arbitrarily selecting 500 particles from the obtained photograph, and using a vernier caliper to calculate the equivalent diameter of each projected area circle. Is measured to obtain an integrated particle size distribution (volume basis), and an average particle diameter (median diameter) is calculated therefrom to obtain a value to be obtained.

Examples of cerium oxide include those represented by chemical formulas such as CeO ₂ and Ce ₂ O ₃ .

  In the present invention, the content of the cerium oxide is 1 to 50 parts by mass, preferably 5 to 45 parts by mass, more preferably 10 to 40 parts by mass with respect to 100 parts by mass of the diene rubber. More preferred. If the amount of cerium oxide is less than 1 part by mass, the low rolling properties, wet performance and wear performance of the tire are not improved, and if 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 blended in a rubber composition for use in tires or the like may be used. it can.

  Specific examples of the sulfur-containing silane coupling agent include, for example, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, 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. 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 based on a ratio (content of the sulfur-containing silane coupling agent / (content of silica + content of cerium oxide) to the total amount of the silica and the cerium oxide. 3) to 20% by mass, preferably 5 to 15% by mass, and more preferably 7 to 10% by mass. When the compounding 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 cerium oxide, the fuel efficiency, wet performance, and abrasion resistance of the tire are not improved, and the rubber is not improved. Workability also deteriorates. On the other hand, when the ratio to the total amount of the silica and the cerium oxide is higher than 20% by mass, the wear performance tends to decrease.

<Other ingredients>
In the composition of the present invention, in addition to the above components, an aromatic terpene resin, a filler other than silica (eg, carbon black, etc.), a silane coupling agent other than the above-mentioned sulfur-containing silane coupling agent, vulcanization Or blending various other additives generally used in tire rubber compositions such as a crosslinking agent, a vulcanization or crosslinking accelerator, zinc oxide, a softener (oil), an antioxidant, and a plasticizer. Can be. The compounding amounts of these additives can be conventional general compounding amounts, as long as the object of the present invention is not adversely affected.

For example, the content of the filler other than silica (for example, carbon black) is preferably 4 to 30 parts by mass, more preferably 5 to 25 parts by mass based on 100 parts by mass of the diene rubber.
The content of the vulcanizing agent or the crosslinking agent is preferably from 0.3 to 3.0 parts by mass, more preferably from 0.5 to 2.5 parts by mass, based on 100 parts by mass of the diene rubber. preferable.
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 a blend with the secondary accelerator. More preferably, the amount is from 0.0 to 2.5 parts by mass.
The content of zinc oxide is preferably from 0.2 to 10.0 parts by mass, more preferably from 0.4 to 5.0 parts by mass, based on 100 parts by mass of the diene rubber.
The content of the softener (oil) is preferably from 10 to 60 parts by mass, more preferably from 15 to 45 parts by mass, based on 100 parts by mass of the diene rubber.
The content of the antioxidant is preferably 0.1 to 5.0 parts by mass, more preferably 0.2 to 4.0 parts by mass, based on 100 parts by mass of the diene rubber.
The content of a plasticizer such as a thermoplastic resin is preferably from 0 to 30 parts by mass, more preferably from 0 to 20 parts by mass, based on 100 parts by mass of the diene rubber.

[Production method]
The rubber composition of the present invention can be produced by mixing and kneading each of the above components.
Among 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 vulcanization (crosslinking) agent and the vulcanization (crosslinking) are added to the masterbatch. ) It is preferable to mix an accelerator and knead the mixture using an open roll or the like to produce a rubber composition. 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 with the masterbatch. By kneading, the kneading time after mixing the vulcanizing (crosslinking) agent and the vulcanizing (crosslinking) accelerator can be shortened, and vulcanized (crosslinked) rubber due to uneven vulcanization (crosslinking) occurring In addition to preventing a decrease in the physical properties of the composition, the vulcanization (crosslinking) can be easily controlled.

[Pneumatic tires]
The pneumatic tire of the present invention is a pneumatic tire manufactured using the above-described composition of the present invention. Especially, it is preferable that it is a pneumatic tire manufactured using the composition of the present invention for a tire tread.
FIG. 1 shows a schematic partial cross-sectional view of a tire representing an example of an embodiment of the pneumatic tire of the present invention. However, 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 of the carcass layer 4 extends around the bead core 5 and the bead filler 6 from the inside of the tire to the outside. It is folded and wound up.
Further, in the tire tread 3, a belt layer 7 is arranged outside the carcass layer 4 over one circumference of the tire.
In the bead portion 1, a rim cushion 8 is disposed at a portion in contact with the rim.

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

  The pneumatic tire of the present invention is excellent in wet grip performance, low fuel consumption performance and wear performance, and is particularly suitable for low fuel consumption tires (tires with low fuel consumption in accordance with the labeling system).

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

[Production of rubber composition]
<Standard example, Examples 1 to 5, Comparative examples 1 to 5>
As shown in the column of the standard example, the column of the example, and the column of the comparative example in Table 1, the rubber compositions according to the standard example, Examples 1 to 5, and Comparative Examples 1 to 5 were each of the components shown in Table 1. Was blended in the amounts shown in Table 1 and produced.
Specifically, first, among the components shown in Table 1 below, components other than sulfur and the vulcanization accelerator were mixed using a 1.7-liter closed Banbury mixer for 5 minutes to reach 150 ± 5 ° C. The masterbatch was released when cooled and cooled to room temperature. Further, sulfur and a vulcanization accelerator were mixed with the obtained master batch using the Banbury mixer to obtain a rubber composition.

[Production 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 produce a vulcanized rubber sheet.

[Test evaluation method]
<Wear performance>
The weight loss of the vulcanized rubber sheet produced as described above was measured using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho) at a temperature of 20 ° C. and a slip ratio of 50% in accordance with JIS K6264-1, 2: 2005. It was measured.
The results are shown in Table 1. The results are expressed as an index according to the following equation, with the abrasion loss of the standard example as 100. The larger the index is, the smaller the wear amount is, and the better the wear performance is when the tire is made.
Abrasion performance = (abrasion amount of standard example / abrasion amount of sample) × 100

<Low fuel consumption performance>
According to JIS K6394: 2007, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.), tan δ (60 ° C.) was obtained under the conditions of an extensional deformation strain of 10% ± 2%, a frequency of 20 Hz, and a temperature of 60 ° C. It was measured.
The results are shown in Table 1. The results were shown as indexes with the standard example as 100. The lower this value, the better the fuel economy performance.

<WET performance>
According to JIS K6394: 2007, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.), tan δ (0 ° C.) was obtained under the conditions of an extensional deformation strain of 10% ± 2%, a frequency of 20 Hz, and a temperature of 0 ° C. 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 greater the tan δ (0 ° C.), and the better the wet grip performance when the tire is made.

[Specific description of each component in the table]
Details of each component shown in the table are as follows.
SBR1: NIPOL1723 (styrene butadiene rubber, manufactured by Zeon Corporation)
-SBR2: NIPOL NS116R (styrene butadiene rubber, manufactured by Zeon Corporation)
BR: Butadiene rubber, Nipol 1220 manufactured by Zeon Corporation
・ Carbon black: Show black N339 (manufactured by Cabot Japan)
^Silica: Zeosil (R) 1165MP (CTAB adsorption specific surface area: 159m ² / g, manufactured by Rhodia)
・ Zinc oxide: 3 types of zinc oxide (manufactured by Shodo Chemical Co., Ltd.)
・ Stearic acid: Bead stearic acid (made by NOF CORPORATION)
Anti-aging agent 1: 6C: SANTOFLEX 6PPD (manufactured by Solutia Europe)
・ Antiaging agent 2: RD: PILNOX TDQ (manufactured by NOCIL LIMITED)
-Sulfur-containing silane coupling agent: bis- (3-triethoxysilylpropyl) tetrasulfide (TESPT), Si69 manufactured by Evonik
Cerium oxide 1: Nano-D CEP manufactured by Nanotechnology, Inc. Average particle size = 25-45 nm
-Cerium oxide 2: FG-50 manufactured by Tri-Baheindustry Co., Ltd. Average particle size = 0.6 to 2.0 m
・ Aroma oil: Extract No.4S (manufactured by Showa Shell Sekiyu KK)
・ Sulfur: Fine powder sulfur containing Kinka Ind.
・ Vulcanization accelerator 1: DPG: Succinol DG (Sumitomo Chemical Co., Ltd.)
Vulcanization accelerator 2: CZ: Noxeller CZ-G (Ouchi Shinko Chemical Co., Ltd.)

[Explanation of test results]
<Examples 1 to 5>
In Examples 1 to 5, the wear performance and the WET performance were able to be improved while suppressing the deterioration of the fuel economy performance.

<Comparative Examples 1 and 2>
In a system containing no cerium oxide and containing a small amount of silica, the wear performance deteriorated. On the other hand, in a system containing a large amount of silica, the fuel economy performance deteriorated.

<Comparative Example 3>
In this embodiment, the amount of cerium oxide is large. In this case, the wear performance and the low fuel consumption performance deteriorated.

<Comparative Example 4>
In this embodiment, the amount of cerium oxide is small. In this case, the wear performance deteriorated.

<Comparative Example 5>
In this embodiment, the average glass transition temperature of the diene rubber is low. In this case, fuel economy performance and WET performance deteriorated.

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

Claims (2)

With respect to 100 parts by mass of a diene rubber having an average glass transition temperature of -50 to -20 ° C, 10 to 80 parts by mass of silica, and 1 to 50 parts by mass of cerium oxide which is fine particles having an average particle size of 20 to 60 nm. A rubber composition for a tire, further comprising a sulfur-containing silane coupling agent in an amount of 3 to 20% by mass relative to the total amount of the silica and the cerium oxide. A pneumatic tire using the rubber composition for a tire according to claim 1 in a tire tread.

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