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 prevents a rubber member disposed between an inner liner and a carcass ply of a pneumatic tire from shrinking after its molding, thus preventing member-to-member peeling in a green tire, and giving a green tire having a stable shape, and a pneumatic tire including the rubber composition.SOLUTION: Disclosed is a rubber composition for 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.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a rubber composition for a rubber member disposed between an inner liner and a carcass ply of a pneumatic tire, and to a pneumatic tire. [Background technology]

[0002] A pneumatic tire is composed of multiple rubber components. In a green tire before vulcanization, if the rubber components shrink after molding, problems such as peeling between components and an unstable shape of the green tire may occur. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2020-523456 [Patent Document 2] Special Publication No. 2017-524065 [Patent Document 3] JP 2015-131640 A Summary of the Invention [Problem to be solved by the invention]

[0004] A rubber member is sometimes disposed between the inner liner and the carcass ply in order to enhance adhesion, and this rubber member is particularly required to be resistant to shrinkage after molding.

[0005] In view of the above, an object of the present invention is to provide a rubber composition and a pneumatic tire using the same, which suppresses post-molding shrinkage of a rubber component arranged between an inner liner and a carcass ply of a pneumatic tire, thereby suppressing peeling between components in a green tire and obtaining a green tire with a stable shape.

[0006] Incidentally, Patent Document 1 describes a rubber composition containing surface-treated pyrolytic carbon black, Patent Document 2 describes a rubber composition containing pyrolytic carbon black coated with a silica layer, and Patent Document 3 describes a rubber composition containing pyrolytic carbon black as an antistatic agent.

[0007] However, none of the documents discloses that by disposing a rubber component made of a rubber composition containing pyrolytic carbon black between the inner liner and the carcass ply of a pneumatic tire, peeling between components in the green tire can be suppressed and a green tire with a stable shape can be obtained. [Means for solving the problem]

[0008] In order to solve the above problems, a rubber composition according to one embodiment of the present invention contains a diene rubber and pyrolytic carbon black, and is disposed between an inner liner and a carcass ply of a pneumatic tire.

[0009] The pyrolytic carbon black may contain 10 to 25% by mass of ash.

[0010] The content of the pyrolytic carbon black may be 10 to 50% by mass of the total inorganic filler.

[0011] A pneumatic tire according to one embodiment of the present invention has the above-mentioned rubber composition disposed between an inner liner and a carcass ply. Effect of the Invention

[0012] According to the rubber composition of the present invention, shrinkage of the rubber members after molding is suppressed, thereby suppressing peeling between the members in the green tire, and a green tire with a stable shape can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, matters related to the implementation of the present invention will be described in detail.

[0014] The rubber composition according to the present embodiment contains a diene rubber and pyrolytic carbon black.

[0015] The diene rubber according to the present embodiment is not particularly limited, but examples thereof include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, and styrene-isoprene-butadiene copolymer rubber. These diene rubbers can be used alone or in a blend of two or more. Among these, natural rubber alone or a combination of natural rubber and styrene butadiene rubber is preferred.

[0016] The pyrolytic carbon black according to the present embodiment can be obtained by a pyrolysis process of used pneumatic tires. The pyrolytic carbon black contains ash, and the content is not particularly limited, but is preferably 10 to 25 mass%. The ash content is a value measured at a measurement temperature of 750°C in accordance with JIS K6220-1. The pyrolytic carbon black is preferably not surface-treated.

[0017] The specific surface area of ​​the pyrolytic carbon black is not particularly limited, but is preferably 60 to 100 m in terms of N2SA specific surface area. 2 / g, and 70 to 90m 2 The N2SA specific surface area is preferably a value measured in accordance with the multipoint method of JIS K6217.

[0018] The rubber composition according to the present embodiment contains pyrolytic carbon black, which can suppress shrinkage of the rubber member after molding. By disposing this rubber member between the inner liner and the carcass ply, peeling between the members in the green tire can be suppressed, and a green tire with a stable shape can be obtained.

[0019] In the rubber composition according to the present embodiment, in addition to pyrolytic carbon black, reinforcing fillers such as silica and carbon black not treated by a pyrolytic process (hereinafter simply referred to as carbon black) can be used as the inorganic filler. That is, the inorganic filler may be a combination of carbon black and pyrolytic carbon black, a combination of silica and pyrolytic carbon black, or a combination of carbon black, pyrolytic carbon black, and silica. Preferably, carbon black and pyrolytic carbon black are used in combination.

[0020] The content of the inorganic filler is not particularly limited, and is, for example, preferably 10 to 70 parts by mass, more preferably 20 to 70 parts by mass, and further preferably 30 to 65 parts by mass, per 100 parts by mass of the rubber component.

[0021] The content of the pyrolytic carbon black is not particularly limited, but is preferably 10 to 50 mass % of the total inorganic filler. When the content of the pyrolytic carbon black is within the above range, shrinkage of the rubber member after molding is easily suppressed.

[0022] The carbon black (excluding pyrolytic carbon black) is not particularly limited, and various known types can be used. The content of carbon black is preferably 5 to 63 parts by mass, more preferably 10 to 63 parts by mass, and further preferably 15 to 58.5 parts by mass, based on 100 parts by mass of the rubber component.

[0023] The silica is not particularly limited, but wet silica such as wet precipitation silica and wet gel silica is preferably used. The content of silica is preferably 0 to 30 parts by mass, more preferably 0 to 20 parts by mass, and further preferably 0 to 10 parts by mass, based on 100 parts by mass of the rubber component.

[0024] The rubber composition according to the present embodiment may further contain a silane coupling agent such as sulfide silane, mercapto silane, etc. The content of the silane coupling agent is preferably 0 to 15 parts by mass relative to 100 parts by mass of silica.

[0025] In addition to the above-mentioned components, the rubber composition according to the present embodiment may contain, as appropriate, compounding chemicals typically used in the rubber industry, such as process oil, zinc oxide, stearic acid, softeners, plasticizers, waxes, antioxidants, vulcanizing agents, and vulcanization accelerators, within normal ranges.

[0026] Examples of the vulcanizing agent include sulfur components such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The content of the vulcanizing agent is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component. The content of the vulcanization accelerator is preferably 0.1 to 7 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0027] The rubber composition according to the present embodiment can be prepared by kneading in a conventional manner using a commonly used mixer such as a Banbury mixer, a kneader, a roll, etc. That is, in the first mixing stage, additives other than the vulcanizing agent and the vulcanization accelerator are added and mixed with the rubber component, and in the final mixing stage, the vulcanizing agent and the vulcanization accelerator are added to the obtained mixture and mixed to prepare the rubber composition.

[0028] The rubber composition thus obtained can be applied between the carcass ply and the inner liner of pneumatic tires of various uses and sizes, such as passenger cars, large tires for trucks and buses, etc. For example, the rubber composition can be molded into a predetermined shape by extrusion processing, combined with other parts to produce a green tire, and then vulcanized and molded at, for example, 130 to 190°C to produce a pneumatic tire.

[0029] The type of pneumatic tire according to the present embodiment is not particularly limited, and as described above, various types of tires such as tires for passenger cars and heavy-duty tires used for trucks, buses, etc. may be mentioned. EXAMPLES

[0030] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0031] Using a Banbury mixer, according to the formulation (parts by mass) shown in Table 1 below, first, in the first mixing stage (non-pro kneading process), the components except for the vulcanization accelerator and sulfur were added and mixed (discharge temperature = 160°C), and to the resulting mixture, in the final mixing stage (pro kneading process), the vulcanization accelerator and sulfur were added and mixed (discharge temperature = 90°C) to prepare a rubber composition.

[0032] Details of each component in Table 1 are as follows.

[0033] Natural rubber: RSS#3 SBR: JSR Corporation "JSR1502" Carbon black: "Seat V" manufactured by Tokai Carbon Co., Ltd., ash content = 0.1 mass%, N2SA specific surface area = 27 m 2 / g Pyrolytic carbon black 1: ash content = 15.1 mass%, N2SA specific surface area = 87 m 2 / g Pyrolytic carbon black 2: ash content = 20.8 mass%, N2SA specific surface area = 75 m 2 / g Zinc oxide: Zinc oxide 3 manufactured by Mitsui Mining & Smelting Co., Ltd. Species " Stearic acid: NOF Corp. "Beads stearic acid" Anti-aging agent: "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Oil: ENEOS Corporation "Process NC140" Sulfur: "Powdered sulfur" manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: Sansera NS-G manufactured by Sanshin Chemical Industry Co., Ltd.

[0034] The ash content in the pyrolytic carbon black was measured at a measurement temperature of 750° C. in accordance with JIS K6220-1.

[0035] The N2SA specific surface area of ​​the pyrolytic carbon black was measured in accordance with the multipoint method of JIS K6217.

[0036] The rubber shrinkage of each of the rubber compositions obtained was evaluated according to the following method.

[0037] Rubber shrinkage 1 (grain direction): The obtained rubber composition was extruded using rolls adjusted to a temperature of 80°C, and the length in the grain direction of the sample immediately after extrusion was measured. The sample was then left to stand at room temperature for 24 hours, and the length in the grain direction of the sample after standing for 24 hours was measured, and the shrinkage degree was calculated based on the following formula. The closer the shrinkage degree is to 0%, the less the sample has shrunk. The grain direction refers to the extrusion direction in which the rubber composition is extruded using rolls. Shrinkage = {(length immediately after extrusion - length after leaving for 24 hours) / length immediately after extrusion} x 100

[0038] Rubber shrinkage 2 (anti-grain direction): The shrinkage was determined in the same manner as above, except that the length of the sample in the anti-grain direction was measured. The closer the shrinkage is to 0%, the less elongation in the anti-grain direction occurs, and the less the sample shrinks. The anti-grain direction refers to the direction perpendicular to the extrusion direction in which the rubber composition was extruded using a roll.

[0039] [Table 1]

[0040] The results are shown in Table 1. Comparing Comparative Example 1 with Examples 1 to 3, it is clear that when pyrolytic carbon black is contained, shrinkage in the grain direction and elongation in the anti-grain direction can be suppressed. [Industrial Applicability]

[0041] The rubber composition of the present invention can be used in various tires for passenger cars, light trucks, buses, etc.

Claims

1. The rubber composition contains a diene rubber and pyrolytic carbon black having an ash content of 10 to 25% by mass, The rubber composition is for use in a rubber member disposed between an inner liner and a carcass ply of a pneumatic tire.

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

3. A pneumatic tire comprising the rubber composition according to claim 1 or 2 disposed between an inner liner and a carcass ply.

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