JP2017075262A - Tire rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which makes it possible to obtain a tire having excellent wet performance and simultaneously excellent fuel economy and wear performance.SOLUTION: A tire rubber composition comprises, based on 100 pts.mass of diene rubber with an average glass transition temperature of -50 to -20°C, 10-80 pts.mass of silica and 1-50 pts.mass of cerium oxide, and also comprises sulfur-containing silane coupling agent at the rate of 3-20 mass% to the total content of the silica and the cerium oxide.SELECTED DRAWING: Figure 1

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 wetness (braking and driving performance on a wet road surface) and low rolling resistance at a higher level.
Conventionally, it is known that the low rolling resistance and wettability are improved by changing the filler blended in the rubber material constituting the tread portion of the tire from carbon black to silica. However, the silica compounded rubber tended to deteriorate the wear performance.

On the other hand, as a conventional method relating to a tire rubber composition, for example, those described in Patent Documents 1 and 2 have been proposed.
Patent Document 1 discloses that a conjugated diene compound-nonconjugated olefin copolymer (A) having a conjugated diene compound-derived content of 40 mol% or more, a conjugated diene polymer (B), and an ethylene-propylene-diene rubber. And a non-conjugated diene compound-nonconjugated olefin copolymer (C) containing a rubber composition, wherein the conjugated diene compound-nonconjugated olefin copolymer (A) is cerium. It is described that a conjugated diene compound and a non-conjugated olefin are polymerized by using a specific compound containing as a polymerization catalyst composition.

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

International Publication No. 2012/117715 Pamphlet JP 2014-231605 A

  As described above, a rubber composition that can provide a tire having excellent wettability and at the same time excellent 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 inventors of the present invention have made extensive studies for solving the above-mentioned problems, and a rubber composition containing a diene rubber having a specific glass transition temperature at a specific ratio, silica, cerium oxide, and a sulfur-containing silane coupling agent. However, the inventors have found that the above object can be achieved and completed the present invention.

  In addition, in the rubber composition 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. The catalyst used in the production process does not include cerium or cerium oxide.

The present invention includes the following (1) to (3).
(1) For 100 parts by mass of diene rubber having an average glass transition temperature of −50 to −20 ° C., 10 to 90 parts by mass of silica and 1 to 50 parts by mass of cerium oxide, and further a sulfur-containing silane coupling agent Is a rubber composition for tires containing 3 to 20% by mass with respect to the total amount of silica and cerium oxide.
(2) The tire rubber composition as described in (1) above, 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 the above (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 wet property, and is excellent also in low-fuel-consumption performance and abrasion performance simultaneously can be provided.

It is a partial section schematic diagram of the tire showing an example of the embodiment of the 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 with respect to 100 parts by mass of diene rubber having an average glass transition temperature of −50 to −20 ° C., and further sulfur-containing silane coupling. It is a rubber composition for tires which contains 3-20 mass% of agents in the ratio with respect to the total amount of the said silica and the said cerium oxide.
Hereinafter, such a rubber composition for tire is also referred to as “the 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), ethylene-propylene-diene copolymer Examples include coalesced rubber (EPDM), styrene-isoprene rubber, isoprene-butadiene rubber, nitrile rubber, and hydrogenated nitrile rubber.

As the diene rubber, for example, one kind in the above specific examples may be used alone, or two or more kinds may be used in combination.
When using individually by 1 type, that whose glass transition temperature of the diene rubber is -50 to -20 ° C is used.
When using 2 or more types together, the value which multiplied and added each mass% of each component to the glass transition temperature of each component is -50--20 degreeC.

  The glass transition temperature of the diene rubber is measured by differential scanning calorimetry (DSC) with a temperature increase rate of 20 ° C./minute, and a low-temperature baseline and a slope of the transition region (slope straight line). The temperature at the intersection of the extension lines. When the diene rubber is an oil-extended product, the glass transition temperature of the diene rubber in a state not containing an oil-extended component (oil) is used.

  As the diene rubber, styrene-butadiene rubber (SBR) and butadiene rubber (BR) are preferably used, and more preferably used in combination, because the wet performance and the low fuel consumption performance can be balanced.

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

<Silica>
The silica which the composition of this invention contains is not specifically limited, The conventionally well-known arbitrary silica currently mix | blended with the rubber composition for uses, such as a tire, can be used.

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

  In the present invention, the silica content is 10 to 80 parts by mass with respect to 100 parts by mass of the diene rubber, and the resulting tire has good wear resistance and a good balance of fuel efficiency. Therefore, it is more preferable that it is 20-70 mass parts, and it is further more preferable that it is 30-60 mass parts.

<Cerium oxide>
The 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, and more preferably 20 to 50 nm.

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

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 with respect to 100 parts by mass of the diene rubber, more preferably 5 to 45 parts by mass, and 10 to 40 parts by mass. Further preferred. When the blending amount of cerium oxide 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 it is possible to use any conventionally known sulfur-containing silane coupling agent blended in a rubber composition for applications such as tires. 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, etc., and these are 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 to the total amount of the silica and the cerium oxide (the content of the sulfur-containing silane coupling agent / (the content of silica + the content of cerium oxide). Amount) × 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 cerium oxide, the low fuel consumption performance, wet performance, and wear resistance of the tire are not improved. Processability also deteriorates. On the other hand, when the ratio with respect to the total amount of the said silica and the said cerium oxide becomes higher than 20 mass%, there exists a tendency for abrasion performance to fall.

<Other ingredients>
In addition to the above components, the composition of the present invention includes an aromatic terpene resin, a filler other than silica (for example, carbon black), a silane coupling agent other than the above sulfur-containing silane coupling agent, and vulcanization. Or various other additives generally used for rubber compositions for tires, such as crosslinking agents, vulcanization or crosslinking accelerators, zinc oxide, softeners (oils), anti-aging agents, plasticizers, etc. Can do. As long as the amount of these additives is not contrary to the object of the present invention, a conventional general amount can be used.

For example, the content of fillers 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 0.3 to 3.0 parts by mass and more preferably 0.5 to 2.5 parts by mass with respect to 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 form of a primary accelerator alone or a blend with a secondary. It is more preferable that it is 0.0-2.5 mass parts.
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 anti-aging agent 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 a 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.

[Production method]
The rubber composition of the present invention can be produced by mixing and kneading the above components.
Among the above components, components other than the vulcanization (crosslinking) agent and the vulcanization (crosslinking) accelerator are mixed and kneaded to create a master batch, and the vulcanization (crosslinking) agent and vulcanization (crosslinking) are added to this master batch. ) It is preferable to produce a rubber composition by mixing an accelerator and kneading using 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 into the masterbatch. When kneaded, the vulcanization (crosslinking) rubber and the vulcanization (crosslinking) accelerator can be mixed to shorten the kneading time, resulting in non-uniform vulcanization (crosslinking). The physical properties of the composition can be prevented from being lowered, and vulcanization (crosslinking) can be easily controlled.

[Pneumatic tire]
The pneumatic tire of the present invention is a pneumatic tire manufactured using the composition of the present invention described above. Especially, it is preferable that it is a pneumatic tire manufactured using the composition of this invention for a tire tread.
FIG. 1 shows a schematic partial sectional view of a tire representing 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.
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 pneumatic tire of the present invention can be manufactured, for example, according to a conventionally known method. Moreover, as gas with which a tire is filled, inert gas, such as nitrogen, argon, helium other than the air which adjusted normal or oxygen partial pressure, can be used.

  Since the pneumatic tire of the present invention is excellent in wet grip performance, low fuel consumption performance and wear performance, it is particularly suitable for a low fuel consumption tire (a tire for low fuel consumption conforming to a labeling system).

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

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

[Production of vulcanized rubber sheet for evaluation]
The manufactured rubber composition (unvulcanized) was press vulcanized at 160 ° C. for 20 minutes in a mold (15 cm × 15 cm × 0.2 cm) to prepare a vulcanized rubber sheet.

[Test evaluation method]
<Abrasion performance>
The vulcanized rubber sheet produced as described above is subjected to wear loss under the conditions of a temperature of 20 ° C. and a slip rate of 50% using a Lambone 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 were expressed as an index according to 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 made into a tire.
Wear performance = (Abrasion amount of standard example / Abrasion amount of sample) × 100

<Low fuel consumption performance>
In accordance with JIS K6394: 2007, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.), tan δ (60 ° C.) under the conditions of an elongation deformation strain rate 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 are shown as an index with the standard example being 100. The lower this value, the better the fuel efficiency.

<WET performance>
In accordance with JIS K6394: 2007, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusyo), tan δ (0 ° C.) under the conditions of an elongation deformation strain rate 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 larger the tan δ (0 ° C.), and the better the wet grip performance when made into a tire.

[Specific description of each component in the table]
The details of each component shown in the table are as follows.
SBR1: NIPOL 1723 (styrene butadiene rubber, manufactured by Nippon Zeon)
-SBR2: NIPOL NS116R (styrene butadiene rubber, manufactured by Nippon Zeon)
BR: Butadiene rubber, Nipol 1220 manufactured by Nippon Zeon
・ 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 Industry Co., Ltd.)
・ Stearic acid: Beads stearic acid (manufactured by NOF Corporation)
Anti-aging agent 1: 6C: SANTOFLEX 6PPD (manufactured by Solutia Europe)
Anti-aging 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: Nanotechnology Nano-D CEP average particle size = 25-45 nm
・ Cerium oxide 2: FG-50 average particle size = 0.6 to 2.0 μm manufactured by Tribahaindustrie
Aroma oil: Extract No. 4 S (manufactured by Showa Shell Sekiyu KK)
・ Sulfur: Fine powder sulfur with Jinhua seal oil (sulfur content 95.24 mass%, manufactured by Tsurumi Chemical Co., Ltd.)
・ Vulcanization accelerator 1: DPG: Soxinol DG (Sumitomo Chemical Co., Ltd.)
・ Vulcanization accelerator 2: CZ: Noxeller CZ-G (Ouchi Shinsei Chemical Co., Ltd.)

[Explanation of test results]
<Examples 1-5>
In Examples 1 to 5, it was possible to improve the wear performance and the WET performance while suppressing the deterioration of the low fuel consumption performance.

<Comparative Examples 1 and 2>
The wear performance was deteriorated in a system containing no cerium oxide and less silica. On the other hand, in the system with a lot of silica, the fuel efficiency performance deteriorated.

<Comparative Example 3>
This is an embodiment with a large amount of cerium oxide. 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>
This is an embodiment in which the average glass transition temperature of the diene rubber is low. In this case, the fuel efficiency and WET performance deteriorated.

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 (3)

  For 100 parts by mass of diene rubber having an average glass transition temperature of −50 to −20 ° C., 10 to 80 parts by mass of silica, 1 to 50 parts by mass of cerium oxide, and further a sulfur-containing silane coupling agent, A rubber composition for tires, containing 3 to 20% by mass with respect to the total amount of silica and cerium oxide.   The tire rubber composition according to claim 1, wherein the cerium oxide is fine particles having an average particle diameter of 20 to 60 nm. A pneumatic tire using the rubber composition according to claim 1 or 2 for a tire tread.

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