JP6540263B2 - Rubber composition - Google Patents

Description

  The present invention relates to rubber compositions.

BACKGROUND ART In recent years, a labeling (display method) system has been enforced for pneumatic tires, and it has been required to achieve both wetness (control and drive on a wet road surface) and low rolling resistance at a higher level.
Heretofore, it has been known that low rolling resistance and wet properties are improved by changing the filler to be blended to the rubber material constituting the tread portion of the tire from carbon black to silica. However, the toughness of the silica-containing rubber tends to be deteriorated as compared with the carbon black-containing rubber due to the difference in the reinforcing structure inside the rubber.

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

WO 2012/117715 pamphlet

  As described above, a rubber composition capable of obtaining a tire excellent in wetness and at the same time low in rolling resistance and also excellent in toughness has not been proposed conventionally.

  An object of the present invention is to provide a rubber composition which can obtain a tire which is excellent in wet property and at the same time low in rolling resistance and also excellent in toughness.

  The inventors of the present invention have conducted intensive studies to solve the above problems, and a rubber composition containing a diene rubber, silica, an antimony oxide compound, and a sulfur-containing silane coupling agent in a specific ratio achieves the above objects. The present invention has been completed.

  In the rubber composition described in Patent Document 1, although it is described that antimony trichloride or antimony pentachloride can be used as a catalyst in the production process, the rubber composition produced and finally obtained In addition, antimony trichloride or antimony pentachloride as a catalyst used in the production process is not included.

The present invention is the following (1) to (2).
(1) 20 to 150 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, and further containing a sulfur-containing silane coupling agent, the total of the silica and the antimony oxide compound The rubber composition containing 3-20 mass% in the ratio with respect to quantity.
(2) The rubber composition as described in (1) above, wherein the antimony oxide compound is a fine particle having an average particle diameter of 20 to 60 nm.

  According to the present invention, it is possible to provide a rubber composition which can obtain a tire which is excellent in wetness and at the same time has low rolling resistance and also excellent toughness.

The present invention will be described.
The present invention contains 20 to 150 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, and further contains a sulfur-containing silane coupling agent with the silica and the antimony oxide compound. It is a rubber composition containing 3 to 20% by mass in a ratio to the total amount.
Such a rubber composition is hereinafter also referred to as "the composition of the present invention".

<Diene-based rubber>
The diene-based rubber contained in the composition of the present invention is not particularly limited as long as it has a double bond in its main chain, and specific examples thereof 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 rubber (EPDM), styrene-isoprene rubber, isoprene-butadiene rubber, nitrile rubber And hydrogenated nitrile rubber and the like, and these may be used alone or in combination of two or more.

  Among these, styrene-butadiene rubber (SBR) and butadiene rubber (BR) are preferably used because it is possible to balance the wet performance and the rolling resistance performance, and it is more preferable to use these in combination.

  When a styrene butadiene rubber (SBR) and a butadiene rubber (BR) are used in combination as a diene rubber, the SBR in the diene rubber is preferably 50 to 90 mass%, and 60 to 85 mass%. Is more preferred. Within this range, the general physical properties of the rubber composition after vulcanization become better.

<Silica>
The silica contained in the composition of the present invention is not particularly limited, and any conventionally known silica blended in rubber compositions for applications such as tires can be used.

  Specific examples of the silica include fumed silica, calcined silica, precipitated silica, crushed silica, fused silica, colloidal silica, etc. 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 20 to 150 parts by mass with respect to 100 parts by mass of the diene rubber, the abrasion resistance of the obtained tire is good, and the balance of the rolling resistance performance is good. Therefore, it is more preferable that it is 50-140 mass parts, and it is further more preferable that it is 70-130 mass parts.

<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, and more preferably 25 to 50 nm.

  For the average particle size, an antimony oxide compound is photographed at a magnification of 5000 times using a transmission electron microscope (TEM), and 500 pieces are arbitrarily selected from the obtained photographs, and each projected area circle equivalent using a caliper The diameter is measured to obtain an integrated particle size distribution (volume basis), and from this, the average particle diameter (median diameter) is calculated to obtain a value.

Examples of antimony oxide compounds include antimony tin oxide, antimony zinc oxide and antimony titanium oxide.
Furthermore, the antimony oxide compound includes antimony oxide.
The antimony oxide compound contained in the composition of the present invention is preferably an antimony-tin oxide type or an antimony-indium oxide type. The conductivity can be imparted to the rubber by blending the tin or indium-based compound, and therefore, it becomes possible to prevent the silica-blended rubber 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, based on 100 parts by mass of the diene rubber, and more preferably 10 to 50 parts by mass. More preferably, it is 40 parts by mass. When the compounding amount of the antimony oxide compound is less than 1 part by mass, the low rolling property, the wet performance and the toughness of the rubber of the tire are not improved, and when it is more than 50 parts by mass, the toughness of the rubber is reduced.

<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 mixed in a rubber composition for applications such as tires may be used. it can.

  Specifically as the silane coupling agent, 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] tetra Sulfide, bis- [3- (triethoxysilyl) -propyl] disulfide, 3-mercaptopropyl-trimethoxysilane, 3-mercaptopropyl-triethoxysilane, etc. may be mentioned, and one of these may be used alone. Well, 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 antimony oxide compound (content of the sulfur-containing silane coupling agent / (content of silica + antimony oxide compound) The content of X) 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, rolling resistance and wet performance of the tire and toughness are not improved and the rubber Processability also deteriorates. On the other hand, when the ratio with respect to the total amount of the said silica and the said antimony oxide compound becomes higher than 20 mass%, toughness will fall.

<Other ingredients>
In the composition of the present invention, in addition to the above-mentioned components, fillers (for example, carbon black etc.) other than silica, vulcanization or crosslinking agent, vulcanization or crosslinking accelerator, zinc oxide, softener (oil), aging Various other additives generally used in tire rubber compositions such as inhibitors and plasticizers can be blended. The blending amounts of these additives can be conventional conventional blending amounts as long as the purpose of the present invention is not violated.

For example, the content of the filler (for example, carbon black) other than silica 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 in a blend with a secondary, More preferably, it is from 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 softener (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 antiaging 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 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.

[Production method]
The rubber composition of the present invention can be produced by mixing and kneading the above-mentioned components.
Among the above components, components other than the vulcanizing (crosslinking) agent and the vulcanizing (crosslinking) accelerator are mixed and kneaded to form a masterbatch, and the masterbatch is made into the vulcanizing (crosslinking) agent and the vulcanizing (crosslinking) The rubber composition is preferably produced by mixing an accelerator and kneading using an open roll or the like. Thus, a masterbatch consisting of components other than the vulcanizing (crosslinking) agent and the vulcanization (crosslinking) accelerator is prepared, and the masterbatch is mixed with the vulcanizing (crosslinking) agent and the vulcanization (crosslinking) accelerator By kneading, it is possible to shorten the kneading time after mixing the vulcanizing (crosslinking) agent and the vulcanizing (crosslinking) accelerator, and a vulcanized (crosslinked) rubber due to the occurrence of nonuniform vulcanization (crosslinking). It is possible to prevent the deterioration of the physical properties of the composition and to facilitate control of vulcanization (crosslinking).

[Pneumatic tire]
A pneumatic tire can be obtained using the composition of the present invention. A pneumatic tire is vulcanized or crosslinked at a temperature according to, for example, the type of diene rubber, vulcanizing agent or crosslinking agent, vulcanization accelerator or crosslinking accelerator contained in the composition of the present invention and the compounding ratio thereof , And the tread portion, the sidewall portion, and the like.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the examples.

[Production of rubber composition]
<Standard Example, Examples 1 to 6, Comparative Examples 1 to 4>
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, the examples 1 to 6 and the comparative examples 1 to 4 have the respective components shown in the table Were prepared by blending them in the amounts shown in Table 1.
Specifically, among the components shown in Table 1 below, the components other than sulfur and the vulcanization accelerator were mixed for 5 minutes using a 1.7 liter closed Banbury mixer, and reached 150 ± 5 ° C. It was discharged when cooled and cooled to room temperature to obtain a masterbatch. Further, using the above-mentioned Banbury mixer, the obtained masterbatch was mixed with sulfur and a vulcanization accelerator to obtain a rubber composition.

  In Table 1, SBR indicates the amount (unit: parts by mass) of the oil-excellent product, and the value in parentheses indicates the net amount (unit: part by mass) of SBR contained in SBR.

[Preparation 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 produce a vulcanized rubber sheet.

[Test evaluation method]
<Toughness>
The vulcanized rubber sheet prepared as described above is punched out of a JIS No. 3 dumbbell-shaped test piece (2 mm in thickness) according to JIS K6251: 2010, and 100% modulus (temperature 100 ° C., tensile speed 500 mm / min) M100: stress at 100% deformation) and breaking strength (E _B : stress at break) were measured. Then, to calculate the M100 ^0.75 × E _B, and the toughness index it.
The measurement results were expressed as an index with the value of the standard example as 100. The larger the value, the better the toughness.
When it is excellent in toughness, breaking strength is large, when it is made into a tire, it is excellent in abrasion resistance and is further excellent in tensile strength.

<Tan δ (60 ° C.)>
The vulcanized rubber sheet produced as described above was subjected to a tensile strain of 10% ± 2%, a frequency of 20 Hz, a temperature of 60 using a visco-elastic spectrometer (manufactured by Iwamoto Seisakusho Co., Ltd.) according to JIS K 6394: 2007. Under the conditions of ° C., tan δ (60 ° C.) was measured.
The measurement results were expressed as an index with the value of the standard example as 100. The smaller the tan δ (60 ° C.), the better the low rolling resistance when made into a tire.

<Wet performance (wet skid)>
It measured based on the method of ASTME-303-83 on the condition of a wet road surface (water temperature 8 degreeC) using British Standard portable skid tester (made by Stanley London). This measurement makes it possible to evaluate grip characteristics (driving performance, braking performance and steering performance) on wet road surfaces.
The measurement results were expressed as an index with the value of the standard example as 100. The higher the value, the better the low temperature wet skid performance.

[Specific explanation of each component in the table]
The details of each component shown in the table are as follows.
SBR: Styrene butadiene rubber having a hydroxyl group (trade name E581, manufactured by Asahi Kasei Co., Ltd.): Oiled product (styrene content: 73% by mass), Tg: -27 ° C, weight average molecular weight: 1,260,000
・ BR: Butadiene rubber, Nippon Zeon Nipol 1220
Silica: Precipitated silica (Zeosil ^(R) 1165MP, manufactured by Rhodia)
Antimony tin oxide 1: Nano-D CEP, average particle size = 30 to 40 nm, manufactured by Nanotechnology
Antimony tin oxide 2: NYACOL SN902SD average particle diameter = 7 μm manufactured by Nyacol Nano Technology
Sulfur-containing silane coupling agent: bis- (3-triethoxysilylpropyl) tetrasulfide (TESPT), Si69 manufactured by Evonik
・ Zinc flower: 3 kinds of zinc oxide (made by Shodo Chemical Industry Co., Ltd.)
-Stearic acid: beads stearic acid (manufactured by NOF Corporation)
・ Anti-aging agent: Flexi-s 6PPD
Oil: Extract No. 4 S (Showa Shell Sekiyu KK)
・ Sulfur: Fine powder sulfur with gold oxide oil (made by Tsurumi Chemical Industry Co., Ltd.)
Vulcanization accelerator 1: Vulcanization accelerator CBS (Noxceler CZ-G, manufactured by Ouchi Shinko Chemical Co., Ltd.)
・ Vulcanization accelerator 2: Suncella DG, manufactured by Sanshin Chemical Industry Co., Ltd.

[Description of test results]
Examples 1-5
(1) The toughness was in the range of 101 to 111 with respect to 100 of the standard example, and a remarkable improvement was observed.
(2) The index of rolling resistance, tan δ (60 ° C.), was within the range of 92 to 116 with respect to 100 of the standard example, and a remarkable improvement was observed.
<3> The wet performance which is an index of the grip property on a wet road surface is in the range of 10 3 to 10 8 with respect to 100 of the standard example, and a remarkable improvement was observed.

Example 6
In Examples 1 to 5, antimony tin oxide having an average particle size of 30 to 40 nm was used, but in Example 6, antimony tin oxide 2 having an average particle size of 7 μm was used. That is, in the case of Example 6, antimony tin oxide having a larger average particle size than that of Examples 1 to 5 was used.
In this case, the toughness, tan δ (60 ° C.) and wet performance were 100, 99 and 101, respectively, relative to 100 of the standard example, and improvements were observed.

Comparative Example 1
It is a comparative example which did not mix | blend antimony tin oxide.
In this case, the toughness deteriorated compared to the standard example.
Moreover, although the silica compounding amount of Comparative Example 1 and the total compounding amount of the silica of Example 2 and antimony tin oxide are the same, in the case of Comparative Example 1 in comparison with Example 2, the toughness and wetness are Is inferior.
The tan δ is inferior to that of the second embodiment.

Comparative Example 2
It is a comparative example which did not mix | blend antimony tin oxide.
In this case, the toughness deteriorated compared to the standard example.
Moreover, although the silica compounding amount of Comparative Example 2 and the total compounding amount of the silica of Example 3 and antimony tin oxide are the same, in the case of Comparative Example 2 in comparison with Example 3, the toughness and wetness are Is inferior.
The tan δ is inferior to that of the third embodiment.

Comparative Example 3
It is a comparative example with many compounding quantities of antimony tin oxide.
In this case, the toughness deteriorated compared to the standard example.
The tan δ was 6% worse than the standard example.

Comparative Example 4
This is a comparative example in which the compounding amount of antimony tin oxide is small.
In this case, the toughness and wetness were comparable as compared with the standard example.
The tan δ was equivalent to the standard example.

Claims (1)

20 to 150 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, and a sulfur-containing silane coupling agent in a ratio to the total amount of the silica and the antimony oxide compound Containing 3 to 20 mass% ,
The rubber composition, wherein the antimony oxide compound is a fine particle having an average particle diameter of 20 to 60 nm.