JP2012062437A - Rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for tires, capable of producing tires improved in dispersibility of silica, increased in reinforcement activity and excellent in wet performance and rolling resistance.SOLUTION: There is provided a rubber composition comprising a diene-based rubber, silica, a sulfur-containing silane coupling agent and an amine compound, wherein the content of the silica is 20-120 pts.mass per 100 pts.mass of the diene-based rubber, the content of the sulfur-containing silane coupling agent is 3-15 pts.mass per 100 pts.mass of silica, the content of the amine compound is 0.5-10 pts.mass per 100 pts.mass of the silica and the amine compound is at least one selected from the group consisting of xanthin, xanthin derivatives, and salts thereof.

Description

  The present invention relates to a rubber composition and a pneumatic tire.

It is known to use a rubber composition containing silica as a technique for improving the wet performance of a tire and reducing rolling resistance. From the viewpoint of further improving the performance, a rubber composition using a silane coupling agent together with silica. Things are also known.
And when mix | blending a silane coupling agent with the composition which mix | blended the silica, when the coupling reaction (silanization) of a silica and a silane coupling agent is inadequate, the favorable dispersibility of a silica is not obtained. When the coupling reaction is excessive, there is a problem in that the quality of the rubber (especially reinforcing property) is deteriorated due to rubber burning.

  In order to solve such a problem, the present applicant has proposed a rubber composition having improved silica dispersibility in Patent Documents 1 to 3.

JP 2007-099896 A JP 2009-256439 A JP 2009-263584 A

  The present invention, like the inventions described in Patent Documents 1 to 3, can improve the dispersibility of silica, improve the reinforcing property, and produce a tire excellent in wet performance and rolling resistance. The purpose is to provide goods.

The present inventor has paid attention to the fact that the dispersibility of silica is improved to increase the breaking strength of rubber and improve the wet performance, and as a result of intensive studies to solve the above problems, xanthine, xanthine By using a rubber composition containing at least one selected from the group consisting of derivatives and salts thereof, a tire having improved wet performance and rolling resistance with improved silica dispersibility and improved reinforcing properties is produced. The present invention has been completed.
That is, the present invention provides the following (1) to (5).

(1) containing a diene rubber, silica, a sulfur-containing silane coupling agent and an amine compound,
The silica content is 20 to 120 parts by mass with respect to 100 parts by mass of the diene rubber,
The content of the sulfur-containing silane coupling agent is 3 to 15 parts by mass with respect to 100 parts by mass of the silica,
The content of the amine compound is 0.5 to 10 parts by mass with respect to 100 parts by mass of the silica.
A rubber composition in which the amine compound is at least one selected from the group consisting of a compound represented by the following formula (I) and a salt thereof.
[Wherein, R ^{1 to} R ³ each independently represents a hydrogen atom or an alkyl group. ]

(2) The rubber composition according to the above (1), wherein R ^{1 to} R ³ in the formula (I) are each independently a hydrogen atom or a methyl group.

(3) The rubber composition according to (1), wherein the compound represented by the formula (I) is a compound represented by any one of the following formulas (1) to (4).

(4) A pneumatic tire using the rubber composition according to any one of (1) to (3) above.

(5) A pneumatic tire using the rubber composition according to any one of (1) to (3) as a tread rubber of a tire.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition for tires which can produce the tire which was excellent in the wet performance and rolling resistance with which the dispersibility of the silica was improved and the reinforcement property improved can be provided.

It is a partial section schematic diagram of the tire showing an example of an embodiment of a tire of the present invention.

1. Rubber composition The rubber composition for tires of the present invention (hereinafter also simply referred to as “the rubber composition of the present invention”) contains a diene rubber, silica, a sulfur-containing silane coupling agent and an amine compound, and the silica The content of is 20 to 120 parts by mass with respect to 100 parts by mass of the diene rubber, and the content of the sulfur-containing silane coupling agent is 3 to 15 parts by mass with respect to 100 parts by mass of the silica. The content of the amine compound is 0.5 to 10 parts by mass with respect to 100 parts by mass of the silica, and the amine compound is at least one selected from the group consisting of xanthine, xanthine derivatives, and salts thereof. It is a certain rubber composition.
Below, each component which the rubber composition of this invention contains is demonstrated in detail.

(1) Diene rubber The diene rubber contained in the rubber composition of the present invention is not particularly limited as long as it has a double bond in the main chain. Specific examples thereof include natural rubber (NR) and 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, hydrogenated nitrile rubber and the like may be mentioned, and these may be used alone or in combination of two or more.

  Of these, styrene-butadiene rubber (SBR) and butadiene rubber (BR) are preferably used, and more preferably used in combination, because the balance between wet performance and reinforcing performance can be achieved.

(2) Silica The silica contained in the rubber composition of the present invention is not particularly limited, and any conventionally known silica compounded in the rubber composition for uses such as tires 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 content of the silica is 20 to 120 parts by mass of silica with respect to 100 parts by mass of the diene rubber, and the resulting tire has good wear resistance and improved strength. More preferably, it is 40-100 mass parts.

(3) Sulfur-containing silane coupling agent The sulfur-containing silane coupling agent contained in the rubber composition of the present invention is not particularly limited, and any conventionally known silane cup compounded in a rubber composition for use such as tires. A ring agent can be used.

  Specific examples of the 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] tetra Examples include sulfide, bis- [3- (triethoxysilyl) -propyl] disulfide, 3-mercaptopropyl-trimethoxysilane, 3-mercaptopropyl-triethoxysilane, and the like. 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 3 to 15 parts by mass with respect to 100 parts by mass of the silica, and the tensile strength after vulcanization of the rubber composition of the present invention at the time of cutting. It is more preferably 5 to 10 parts by mass because the physical properties such as elongation are improved.

(4) Amine compound The amine compound contained in the rubber composition of the present invention is an additive added from the viewpoint of promoting the coupling reaction (silanization) between the silica and the silane coupling agent described above. It is a compound represented by (I).

[Wherein, R ^{1 to} R ³ each independently represents a hydrogen atom or an alkyl group. ]

When alkyl groups are selected for two or more of R ^{1 to} R ³ , they are independently selected. That is, different alkyl groups may be selected, the same alkyl group may be selected, or two of the three may be the same and the other one may be a different alkyl group. .

Here, the alkyl group is not particularly limited, and examples thereof include a C _1-8 chain alkyl group and a C _3-10 alicyclic alkyl group.

Specific examples of the C _1-8 chain alkyl group include, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n -Propyl group, isopropyl group, neopropyl group, tert-propyl group and the like. Among these, a methyl group, an ethyl group or a propyl group is preferable, a methyl group or an ethyl group is more preferable, and a methyl group is more preferable.

Specific examples of the alicyclic alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Further, for example, it may be a bicycloalkyl group derived from bicyclo [1,1,0] butane, bicyclo [2,2,2] octane or other C _4-10 bicycloalkane.

  As the compound represented by the above formula (I), a compound represented by any one of the following formulas (1) to (4) is preferably exemplified because of its large silanization promoting effect. That is, the amine compound contained in the composition of the present invention is preferably at least one selected from the group consisting of compounds represented by any of the following formulas (1) to (4).

  In addition, since these are all amine compounds derived from natural products, they also have an advantage that they can greatly contribute to the reduction of environmental burden compared to petroleum-based synthetic compounds.

  Moreover, in this invention, content of the said amine compound is 0.5-10 mass parts with respect to 100 mass parts of said silica, The high dispersibility and modulus characteristic of the silica of the rubber composition of this invention obtained are obtained. Is more preferably 2.0 to 10 parts by mass from the reason that can be kept good.

(5) Components other than the above In addition to the above components, the rubber composition of the present invention includes a filler other than silica (for example, carbon black), a vulcanization or crosslinking agent, a vulcanization or crosslinking accelerator, zinc oxide, Various other additives generally used in tire rubber compositions such as oils, antioxidants, and plasticizers can be blended. 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.

2. Method for Producing Rubber Composition The rubber composition of the present invention can be produced by mixing and kneading the above components. Among the above components, a vulcanization (crosslinking) agent and a vulcanization (crosslinking). Mixing and kneading ingredients other than accelerators to create a master batch, mixing this master batch with a vulcanization (crosslinking) agent and a vulcanization (crosslinking) accelerator, kneading using an open roll, etc., and rubber composition It is preferable to produce a product. 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.

3. Pneumatic tire The pneumatic tire of the present invention (hereinafter also simply referred to as “the tire of the present invention”) is a pneumatic tire using the above-described rubber composition of the present invention.
FIG. 1 shows a schematic partial sectional view of a tire representing an example of an embodiment of the tire of the present invention, but the 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 tire of the present invention is vulcanized or cured at a temperature corresponding to, for example, the diene rubber, vulcanizing agent or crosslinking agent, vulcanization accelerator or crosslinking accelerator contained in the rubber composition of the present invention and the blending ratio thereof. It can manufacture by bridge | crosslinking and forming a tread part, a side wall part, etc.

  In the present invention, from the viewpoint of utilizing the effects of the present invention in which the dispersibility of silica is improved, the decrease in reinforcement is suppressed, and the wet performance and rolling resistance are excellent, the tire has a larger amount of silica than other members. It is preferable to form the tread portion with the rubber composition of the present invention.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to these examples.

1. Rubber composition The composition of each rubber composition according to Standard Example 1, Examples 1 to 6 and Comparative Examples 1 and 2 is shown in the column of "Rubber Composition" in Table 1 (the unit is parts by mass). In the composition shown in the column of “Rubber composition” in Table 1, each component except the vulcanization accelerator and the vulcanizing agent is kneaded for 9 minutes with a 1.5 liter closed mixer and reaches 150 ° C. To obtain a master batch. A vulcanization accelerator and a vulcanizing agent were kneaded with this master batch with an open roll to obtain a rubber composition.

2. Physical property evaluation (1) M300 / M100 (index of reinforcement)
The obtained rubber composition was press vulcanized at 160 ° C. for 20 minutes using a 150 × 150 × 2 mm mold to form a vulcanized rubber sheet having a thickness of 2 mm.
A No. 3 dumbbell-shaped test piece was punched from this vulcanized rubber sheet, 100% modulus (M100) and 300% modulus (M300) were measured according to JIS K 6251: 2004, and a value of M300 / M100 was obtained. . The value of M300 / M100 of Examples 1 to 6 and Comparative Examples 1 and 2 was expressed as a percentage (%) with the value of Standard Example 1 as a reference (100%). This was used as an index of reinforcement.
Numerical values are shown in the column of M300 / M100 in Table 1. Larger numbers are better.

(2) TB (indicator of silica reinforcement)
A No. 3 dumbbell-shaped test piece was prepared, and TB (tensile strength) was measured according to JIS K 6251: 2004 (unit: MPa). The measured values of Examples 1 to 6 and Comparative Examples 1 and 2 were expressed as percentages (%) with the measured value of Standard Example 1 as a reference (100%).
Numerical values are shown in the TB column of Table 1. Larger numbers are better.

(3) EB (indicator of silica reinforcement)
A No. 3 dumbbell-shaped test piece was prepared, and EB (elongation at break) was measured in accordance with JIS K 6251: 2004 (unit:%). The measured values of Examples 1 to 6 and Comparative Examples 1 and 2 were expressed as percentages (%) with the measured value of Standard Example 1 as a reference (100%).
Numerical values are shown in the EB column of Table 1. Larger numbers are better.

(4) ΔG ′ (indicator of dispersibility of silica)
Vulcanization was carried out at 160 ° C. for 20 minutes using unvulcanized rubber, and strain shear stress G ′ having a strain rate of 0.28% to 30.0% was measured (unit: MPa). For the measurement, a viscoelasticity measuring device RPA2000 (manufactured by Alpha Technologies) was used. The difference ΔG ′ = (G ′ _0.28 −G ′ ₃₀ ) between G ′ (G ′ _0.28 ) when the strain rate is 0.28% and G ′ (G ′ _30.0 ) when the strain is 30.0%. _0.0 ), and the measured values of Examples 1 to 6 and Comparative Examples 1 and 2 were expressed in percentage (%) with the measured value of Standard Example 1 as a reference (100%).
Numerical values are shown in the column of ΔG ′ in Table 1. The smaller the value, the better the silica dispersibility.

Each component shown in the column of the rubber composition in Table 1 is as follows. In Table 1, the blending amount of each component of the rubber composition is (B) silica, (E) vulcanizing agent, (F) vulcanization accelerator, (G) vulcanization acceleration aid, and (H). About other compounding agents, (A) Relative value (part by mass) when the total of diene rubber is 100 parts by mass, (C) about sulfur-containing silane coupling agent and (D) amine compound, B) Relative values (parts by mass) when silica is 100 parts by mass are shown.
(A) Diene rubber Diene rubber 1: VSL-5025 HM-1 (styrene-butadiene rubber (SBR); manufactured by LANXCESS; oil exhibition, Table 1 shows rubber content excluding oil)
Diene rubber 2: Nipol 1220 (Butadiene rubber (BR); manufactured by Nippon Zeon)
(B) Silica Silica 1: Zeosil 1165MP (silica; manufactured by Rhodia)
(C) Sulfur-containing silane coupling agent Silane coupling agent 1: Si69 (bis [3- (triethoxysilyl) propyl] tetrasulfide; manufactured by Degussa)
(D) Amine compound Amine compound 1: Caffeine (caffeine; manufactured by Tokyo Chemical Industry Co., Ltd.)
Sulfur 1: Oil-treated sulfur (sulfur; manufactured by Hosoi Chemical Co., Ltd .; 5.1% oil content, Table 1 shows sulfur content excluding oil)
(F) Vulcanization accelerator Vulcanization accelerator 1: Suntocure CBS (N-cyclohexyl-2-benzothiazole; manufactured by FLEXSYS)
Vulcanization accelerator 2: Parkasit DPG (N, N'-diphenylguanidine; manufactured by FLEXSYS)
(G) Vulcanization acceleration aid Vulcanization acceleration aid 1: 3 types of zinc white (Zinc oxide; manufactured by Shodo Chemical Co., Ltd.)
Vulcanization acceleration aid 2: beads stearic acid YR (stearic acid; manufactured by NOF Corporation)
(H) Other compounding agents Oil 1: Process X-140 (Process oil; manufactured by Japan Energy)

3. Description of results of physical property evaluation From the results shown in Table 1 above, the rubber compositions of Examples 1 to 6 prepared by blending a predetermined amount of caffeine (compound represented by the following formula (1)) Compared with the rubber composition of Standard Example 1 prepared without blending, a tire having improved silica dispersibility (ΔG ′), improved reinforcing properties (TB, EB), and excellent wet performance and rolling resistance. It was found that it can be produced.

  On the other hand, the rubber composition of Comparative Example 1 prepared by blending a small amount of caffeine has little improvement effect compared to the rubber composition of Standard Example 1, and the rubber of Comparative Example 2 prepared by blending a large amount of caffeine. The composition was found to have improved silica dispersibility (ΔG ′) but lower reinforcement (TB, EB) than the rubber composition of Standard Example 1.

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 (5)

Containing a diene rubber, silica, a sulfur-containing silane coupling agent and an amine compound,
The silica content is 20 to 120 parts by mass with respect to 100 parts by mass of the diene rubber,
The content of the sulfur-containing silane coupling agent is 3 to 15 parts by mass with respect to 100 parts by mass of the silica,
The content of the amine compound is 0.5 to 10 parts by mass with respect to 100 parts by mass of the silica,
A rubber composition in which the amine compound is at least one selected from the group consisting of a compound represented by the following formula (I) and a salt thereof.
[Wherein, R ^{1 to} R ³ each independently represents a hydrogen atom or an alkyl group. ] 2. The rubber composition according to claim 1, wherein in the formula (I), R ^{1 to} R ³ are each independently a hydrogen atom or a methyl group. The rubber composition according to claim 1, wherein the compound represented by the formula (I) is a compound represented by any one of the following formulas (1) to (4).
  A pneumatic tire using the rubber composition according to claim 1.   The pneumatic tire which used the rubber composition in any one of Claims 1-3 for the tread rubber of a tire.