JP6657761B2 - Rubber composition for tire - Google Patents

Description

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

2. Description of the Related Art In recent years, a labeling (display method) system has been applied to pneumatic tires, and a more advanced fuel-efficient technology is required.
Conventionally, a method of improving the low rolling resistance of a tire by blending silica has been proposed. However, at the same time, the viscosity tends to increase to deteriorate workability, and in addition, the wear performance tends to deteriorate.

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.

  Patent Document 2 discloses that a 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 a 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 having excellent fuel economy performance and also excellent workability 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 fuel economy performance and also excellent workability and wear performance.

  The present inventors have intensively studied to solve the above problems, at a specific ratio, a specific diene rubber, carbon black, including cerium oxide, a rubber composition having specific physical properties, the above-mentioned object. And accomplished 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 (4).
(1) For 100 parts by mass of a diene rubber containing 30 to 70% by mass of natural rubber and / or synthetic polyisoprene, carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 91 to 150 m ² / g is used in an amount of 30 to 150%. A rubber composition for a tire, comprising 100 parts by mass, 1 to 30 parts by mass of cerium oxide, and having a 100% modulus of 2.5 to 7.0 MPa when subjected to a tensile test.
(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) The rubber for a tire according to the above (1) or (2), further comprising silica, wherein the sulfur-containing silane coupling agent is contained in an amount of 3 to 20% by mass relative to the total amount of the silica and the cerium oxide. Composition.
(4) A pneumatic tire using the rubber composition for a tire according to any one of the above (1) to (3) for a rim cushion.

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

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 relates to 100 parts by mass of a diene rubber containing 30 to 70% by mass of natural rubber and / or synthetic polyisoprene, and 30 parts of carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 91 to 150 m ² / g. It is a rubber composition for tires containing 100 parts by mass and 1 to 30 parts by mass of cerium oxide and having a 100% modulus of 2.5 to 7.0 MPa when subjected to a tensile test.
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 contains 30 to 70% by mass of natural rubber and / or synthetic polyisoprene. That is, the total content of the natural rubber and the synthetic polyisoprene contained in the diene rubber is 30 to 70% by mass. If this total content is too low, the fracture properties tend to deteriorate.

  Components other than the natural rubber and the synthetic polyisoprene contained in the diene rubber are not particularly limited as long as they are diene rubbers having a double bond in the main chain. Specific examples include butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), and the like. These may be used alone or in combination of two or more. The molecular weight and microstructure are not particularly limited, and may be terminal-modified with an amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl group, or the like, or may be epoxidized.

As the diene rubber, it is preferable to use butadiene rubber (BR) because a balance between abrasion resistance and fuel economy can be achieved.
When butadiene rubber (BR) is used as the diene rubber, the BR in the diene rubber is preferably from 10 to 70% by mass, more preferably from 30 to 50% by mass. Within this range, the general physical properties of the vulcanized rubber composition will be better.

<Carbon black>
Carbon black-containing compositions of the present invention, the nitrogen adsorption specific surface area (N ₂ SA) is 91~150m ² / g, more preferably 100~120m ² / g.
In addition, the nitrogen adsorption specific surface area (N ₂ SA) is a value obtained in accordance with JIS K6217-2.

  In the present invention, the content of the carbon black is 30 to 100 parts by mass with respect to 100 parts by mass of the diene rubber, the resulting tire has good abrasion resistance, and a good balance of low fuel consumption performance. Therefore, the content is more preferably 30 to 75 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 a cerium oxide compound with a transmission electron microscope (TEM) at a magnification of 5,000 times, and arbitrarily selecting 500 pieces from the obtained photographs and using a caliper to correspond to each projected area circle. The diameter is measured to determine the integrated particle size distribution (volume basis), and the average particle diameter (median diameter) is calculated therefrom to obtain a value to be determined.

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 30 parts by mass, more preferably 5 to 30 parts by mass, based on 100 parts by mass of the diene rubber. When the compounding amount of cerium oxide is less than 1 part by mass, the low rolling property, toughness and processing performance of the tire are not improved, and when it is more than 30 parts by mass, the processability, toughness and physical properties at break tend to decrease.

<Silica>
Preferably, the composition of the present invention contains silica.
When the composition of the present invention contains silica, the silica 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 preferably 10 to 50 with respect to 100 parts by mass of the diene rubber, and the resulting tire has good abrasion resistance and a good balance of low fuel consumption performance. Therefore, the content is more preferably 20 to 45 parts by mass.

<Sulfur-containing silane coupling agent>
Preferably, the compositions of the present invention include a sulfur-containing silane coupling agent.
The sulfur-containing silane coupling agent is not particularly limited, and any conventionally known sulfur-containing silane coupling agent blended in a rubber composition for use in tires and the like can be used.

  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 a ratio (the content of only the cerium oxide when no silica is contained) to the total amount of the silica and the cerium oxide (the content of the sulfur-containing silane coupling agent). Is preferably 3 to 20% by mass, more preferably 5 to 15% by mass, and more preferably 7 to 10% by mass as (content of silica / (content of silica + content of cerium oxide) × 100). Is more preferable. 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 content of only cerium oxide when no silica is contained), the fuel efficiency of the tire is low. In addition, the processability and toughness are not improved, and the processability of the rubber is also deteriorated. 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, a filler other than silica and carbon black, a silane coupling agent other than the sulfur-containing silane coupling agent, a vulcanizing or crosslinking agent, a vulcanizing or crosslinking accelerator , Zinc oxide, a softener (oil), an antioxidant, a plasticizer, and other various additives commonly used in rubber compositions for tires. 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 vulcanizing agent or the crosslinking agent is preferably from 0.3 to 3.0 parts by mass, and more preferably from 0.5 to 2.5 parts by mass based on 100 parts by mass of the diene rubber. Is more preferred.
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 softening agent (oil) is preferably 1 to 50 parts by mass, more preferably 5 to 20 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, 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.

<Physical properties: 100% modulus>
The composition of the present invention contains each of the above components, and has a 100% modulus of 2.5 to 7.0 MPa when subjected to a tensile test.
That is, the composition of the present invention (unvulcanized) is press-vulcanized in a mold (15 cm × 15 cm × 0.2 cm) at 160 ° C. for 20 minutes to produce a vulcanized rubber sheet, which complies with JIS K6251: 2010. Then, a JIS No. 3 dumbbell-type test piece (thickness: 2 mm) was punched out, and a stress at the time of 100% deformation (100% modulus) measured by performing a tensile test at a temperature of 100 ° C. and a tensile speed of 500 mm / min, It becomes 2.5-7.0 MPa.
This 100% modulus is preferably from 3.0 to 5.5 MPa, and more preferably from 3.5 to 4.5 MPa.

[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. Among them, a pneumatic tire manufactured by using the composition of the present invention for a rim cushion is preferable.
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.

  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 8, Comparative examples 1 to 5>
As shown in the columns of the standard examples, the examples, and the comparative examples in Tables 1 and 2, the rubber compositions according to the standard examples 1, the standard examples 2, the examples 1 to 8, and the comparative examples 1 to 5 are shown. Was prepared by blending the components shown in Tables 1 and 2 in the amounts shown in Tables 1 and 2.
Specifically, first, the components excluding sulfur and the vulcanization accelerator among the components shown in Tables 1 and 2 below were mixed for 5 minutes using a 1.7-liter closed Banbury mixer, and 150 ± Released when the temperature reached 5 ° C., and cooled to room temperature to obtain a master batch. 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]
<Workability>
According to JIS K6300, using an L-type rotor (38.1 mm diameter, 5.5 mm thickness) with a Mooney viscometer, preheating time 1 minute, rotor rotation time 4 minutes, 100 ° C, 2 rpm did.
The results are shown in Tables 1 and 2. The results were shown as indexes with the standard example as 100. The lower the value, the lower the viscosity and the better the processability.

<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 Tables 1 and 2. The results were shown as indexes with the standard example as 100. The lower this value, the better the fuel economy performance.

<100% modulus>
With respect to the vulcanized rubber sheet produced as described above, a JIS No. 3 dumbbell-type test piece (thickness: 2 mm) was punched out in accordance with JIS K6251: 2010, and the 100% modulus (at a temperature of 100 ° C. and a tensile speed of 500 mm / min) was used. M100: stress at 100% deformation) was measured.
The results are shown in Tables 1 and 2.
The 100% modulus indicates the measurement result of the actually measured value (MPa).

<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 Tables 1 and 2. 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

[Specific description of each component in the table]
Details of each component shown in the table are as follows.
・ NR: Natural rubber TSR20
・ BR: ZEON NIPOL 1220
・ Carbon black: Niteron # 300 manufactured by Shin Nikka Carbon Co., Ltd., N ₂ SA 117 m ² / g
-Silica: Nipsil AQ manufactured by Tosoh Silica Co., Ltd.-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 = 0.6-2.0 m
-Zinc oxide: 3 types of zinc oxide manufactured by Shodo Chemical Co., Ltd.-Sulfur-containing silane coupling agent: bis- (3-triethoxysilylpropyl) tetrasulfide (TESPT), Si69 manufactured by Evonik
Aroma oil: Diana Process NH-60 manufactured by Idemitsu Kosan Co., Ltd.
-Stearic acid: Stearic acid YR manufactured by NOF Corporation
-Wax: OZOACE-0015A manufactured by Nippon Seiro Co., Ltd.
Anti-aging agent: SANTOFLEX 6PPD manufactured by FLEXSYS
・ Sulfur: Fine powder sulfur with Tanami Chemical Industry Co., Ltd. containing Kinka stamp oil (sulfur content 95.24 wt%)
・ Vulcanization accelerator: SANTOCURE CBS manufactured by FLEXSYS

[Explanation of test results]
<Examples 1 to 8>
In Examples 1 to 8, low fuel consumption performance, workability and wear performance were able to be improved.

<Comparative Examples 1, 3, 4>
This is an embodiment in which cerium oxide is not contained or its amount is small. In this case, the wear performance or workability deteriorated.

<Comparative Examples 2 and 5>
In this embodiment, the amount of cerium oxide is large. In this case, fuel economy performance and wear 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 (4)

30 to 100 parts by mass of carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 91 to 150 m ² / g with respect to 100 parts by mass of a diene rubber containing 30 to 70% by mass of natural rubber and / or synthetic polyisoprene. A rubber composition for a tire, comprising 1 to 30 parts by mass of cerium oxide and having a 100% modulus of 2.5 to 7.0 MPa when subjected to a tensile test at a temperature of 100 ° C.   The rubber composition for a tire according to claim 1, wherein the cerium oxide is fine particles having an average particle diameter of 20 to 60 nm.   The rubber composition for a tire according to claim 1 or 2, further comprising silica, wherein the sulfur-containing silane coupling agent is contained 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 any one of claims 1 to 3 for a rim cushion.

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