RUBBER COMPOSITION FOR RUBBER MEMBER DISPOSED BETWEEN INNER LINER AND CARCASS PLY OF PNEUMATIC TIRE, AND PNEUMATIC TIRE

Abstract

To provide a rubber composition that suppresses shrinkage after molding of a rubber member disposed between an inner liner and a carcass ply of a pneumatic tire, thereby suppressing peeling between members in a green tire and obtaining a green tire having a stable shape, and a pneumatic tire using the rubber composition. Disclosed is a rubber composition for use in a rubber member disposed between an inner liner and a carcass ply of a pneumatic tire, the composition containing a diene-based rubber and a pyrolytic carbon black.

Claims

1. A rubber composition for use in a rubber member disposed between an inner liner and a carcass ply of a pneumatic tire, the composition comprising a diene-based rubber and a pyrolytic carbon black as an inorganic filler.

2. The rubber composition according to claim 1, wherein the pyrolytic carbon black contains an ash content of 10 to 25% by mass.

3. The rubber composition according to claim 1, wherein the content of the pyrolytic carbon black is 10 to 50% by mass of the total inorganic filler.

4. The rubber composition according to claim 2, wherein the content of the pyrolytic carbon black is 10 to 50% by mass of the total inorganic filler.

5. A pneumatic tire comprising the rubber composition according to claim 1 disposed between an inner liner and a carcass ply.

6. A pneumatic tire comprising the rubber composition according to claim 2 disposed between an inner liner and a carcass ply.

7. A pneumatic tire comprising the rubber composition according to claim 3 disposed between an inner liner and a carcass ply.

8. A pneumatic tire comprising the rubber composition according to claim 4 disposed between an inner liner and a carcass ply.

Description

EXAMPLES

[0029] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0030] Using a Banbury mixer, according to the mix proportion (parts by mass) shown in Table 1 below, components other than a vulcanization accelerator and sulfur were added and mixed (discharge temperature=160° C.) in the first mixing stage (non-processing kneading process), and a vulcanization accelerator and sulfur were added and mixed (discharge temperature=90° C.) in the final mixing stage (processing kneading process) to prepare a rubber composition.

[0031] The details of each component in Table 1 are as follows. [0032] Natural rubber: RSS #3 [0033] SBR: “JSR1502” manufactured by JSR Corporation [0034] Carbon Black: “SEAST V” manufactured by Tokai Carbon Co., Ltd., ash content=0.1% by mass, N.sub.2SA specific surface area =27 m.sup.2/g [0035] Pyrolytic carbon black 1: ash content=15.1% by mass, N2SA specific surface area=87 m.sup.2/g [0036] Pyrolytic carbon black 2: ash content =20.8% by mass, N2SA specific surface area=75 m.sup.2/g [0037] Zinc oxide: “Zinc Oxide Type III” manufactured by Mitsui Mining & Smelting Co., Ltd. [0038] Stearic acid: “Bead Stearic Acid” manufactured by NOF Corporation [0039] Aging inhibitor: “NOCRAC 6C” manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. [0040] Oil: “Process NC140” manufactured by ENEOS Corporation [0041] Sulfur: “Powdered sulfur” manufactured by Tsurumi Chemical Industry Co., Ltd. [0042] Vulcanization accelerator: “Sanceler NS-G” manufactured by Sanshin Chemical Industry Co., Ltd.

[0043] The ash content in the pyrolytic carbon black was measured in accordance with JIS K6220-1 at a measuring temperature of 750° C.

[0044] The N2SA specific surface area of the pyrolytic carbon black was measured in accordance with the multipoint method of JIS K6217.

[0045] With respect to each of the rubber compositions obtained, the shrinkage property of the rubber was evaluated. The evaluation method is as follows. [0046] Rubber shrinkage 1 (grain direction): The obtained rubber composition was extruded using a roll whose temperature was adjusted to 80° C., and then the length in the grain direction of the sample immediately after extrusion was measured. Thereafter, the sample was allowed to stand at room temperature for 24 hours, the length in the grain direction of the sample after allowing to stand for 24 hours was measured, and the degree of shrinkage was obtained based on the following formula. A degree of shrinkage closer to 0% indicates that the sample has not shrunk. Note that the grain direction refers to an extrusion direction in which the rubber composition is extruded using a roll.

[0047] Degree of shrinkage={(length immediately after extrusion—length after standing for 24 hours)/length immediately after extrusion}×100 [0048] Rubber shrinkage 2 (against-the-grain direction): The degree of shrinkage was determined in the same manner as described above except that the length of the sample in the against-the-grain direction was measured. As the degree of shrinkage is closer to 0%, there is no elongation in the against-the-grain direction, indicating that the sample has not shrunk. Note that the against-the-grain direction refers to a direction orthogonal to the extrusion direction in which the rubber composition is extruded using a roll.

TABLE-US-00001 TABLE 1 Comparative Example Example Example Example 1 1 2 3 Natural rubber 50 50 50 50 SBR 50 50 50 50 Carbon black 60 52 45 30 Pyrolytic carbon — 8 15 — black 1 Pyrolytic carbon — — — 30 black 2 Zinc oxide 3 3 3 3 Stearic acid 1 1 1 1 Aging inhibitor 1 1 1 1 Oil 10 10 10 10 Sulfur 2 2 2 2 Vulcanization 1 1 1 1 accelerator Rubber shrinkage 1 24 21 19 17 (grain direction) Rubber shrinkage 2 −10 −7 −6 −5 (against-the-grain direction)

[0049] The results are as shown in Table 1, and it can be seen from the comparison between Comparative Example 1 and Examples 1 to 3 that shrinkage in the grain direction and elongation in the against-the-grain direction could be suppressed in the case of containing pyrolytic carbon black. Industrial Applicability

[0050] The rubber composition of the present invention can be used for various tires such as passenger cars, light trucks, and buses.