JP6527019B2 - Rubber composition for tire and tire using the same - Google Patents

Description

  The present invention relates to a rubber composition for a tire and a tire using the same. More specifically, the present invention relates to a cushion rubber composition for retread tires used as a cushion rubber for retread tires, and a retread tire using the same. The present invention also relates to a tire inner liner or a rubber composition for squeegee, and a pneumatic tire using the same.

  For example, in heavy-duty pneumatic tires such as trucks and buses, retreading of the tire called retread may be performed. There is a method of bonding the tread rubber and the base tire by bonding the vulcanized tread rubber to the crown portion of the base tire via the cushion rubber, and is referred to as a pre-cure method. In the retread tire manufactured by the pre-cure method, the cushion rubber needs to have the fatigue resistance that adheres the vulcanized rubbers and does not peel off the tread rubber in the market use. Thus, cushion rubber is important in improving the durability of retread tire (tread resistance of tread rubber), and various proposals have been made (see, for example, Patent Document 1).

  On the other hand, the pneumatic tire comprises a carcass ply formed by coating a carcass cord with a coating rubber, and an inner liner for holding air pressure on the inner circumferential side of the carcass ply. Further, in order to prevent the carcass cords from being exposed to the inner liner side, a rubber sheet called a squeegee is interposed between the inner liner and the carcass ply. Conventionally, various proposals have been made as rubber compositions used for inner liners and squeegees (see, for example, Patent Documents 2 to 4). During the running of the pneumatic tire, peeling may occur between the inner liner and the carcass ply to impair the durability of the tire. Therefore, the rubber composition used for the inner liner and the squeegee is important in improving the durability of the tire.

  By the way, it is disclosed by patent document 2 to mix | blend a wax process zinc oxide with the rubber composition for inner liners. However, there is no disclosure of formulating zinc oxide treated with an organic acid.

  Further, in Patent Document 5, a rubber composition for a tire used for tread rubber or sidewall rubber of a pneumatic tire is surface-treated with an organosilane compound in order to improve mechanical properties such as breaking strength and low heat buildup. Techniques using the treated zinc oxide have been proposed. Although this example also discloses an example in which zinc oxide treated with propionic acid is compounded, it is described as a comparative example in which the effect is not sufficient, and zinc oxide treated with such an organic acid is used as a cushion for retread tire Neither the point of using for rubber | gum, an inner liner, squeegee nor the point of using what has a large nitrogen adsorption specific surface area as a process zinc oxide is disclosed.

JP, 2008-094266, A JP, 2011-116846, A Japanese Patent Application Laid-Open No. 06-087976 JP, 2013-018816, A JP 2012-149159 A

  The first invention aims to provide a cushion rubber composition of a retread tire capable of improving the durability of a retread tire, and a retread tire using the same.

  A second invention aims to provide a tire inner liner or a squeegee rubber composition capable of improving the durability of a pneumatic tire, and a pneumatic tire using the same.

The cushion rubber composition for retread tire according to the first invention has a nitrogen adsorption specific surface area of 6 m ² / g or more, which is treated with an aliphatic monocarboxylic acid having 2 to 10 carbon atoms per 100 parts by mass of diene rubber. The treated zinc oxide of the present invention contains 0.1 to 10 parts by mass of treated zinc oxide in which the amount of aliphatic monocarboxylic acid to be treated is 0.01 to 10 parts by mass with respect to 100 parts by mass of zinc oxide . In the retread tire according to the first aspect of the present invention, the cushion rubber composition is used as a cushion rubber which is interposed between a base tire and a tread rubber to bond them.

The rubber composition for a tire inner liner or squeegee according to the second invention has a nitrogen adsorption specific surface area of 6 m ² / g, which is treated with an aliphatic monocarboxylic acid having 2 to 10 carbon atoms per 100 parts by mass of the rubber component. The treated zinc oxide described above contains 0.1 to 10 parts by mass of treated zinc oxide in which the amount of aliphatic monocarboxylic acid to be treated is 0.01 to 10 parts by mass with respect to 100 parts by mass of zinc oxide . Further, a pneumatic tire according to a second aspect of the invention uses the rubber composition for an inner liner and / or a squeegee.

  According to the first invention, by using the treated zinc oxide having a high nitrogen adsorption specific surface area, which is treated with an organic acid, as the cushion rubber composition for retread tire, the cushion rubber is used as the base tire and tread rubber on the front and back sides. On the other hand, it adheres firmly, so that the durability of the retread tire can be improved.

  According to the second invention, by using the treated zinc oxide having a high nitrogen adsorption specific surface area, which is treated with an organic acid, for the inner liner or the rubber composition for squeegee, the peeling between the inner liner and the carcass ply is prevented. The durability of the pneumatic tire can be improved.

(First embodiment: cushion rubber composition for retread tire)
The cushion rubber composition for retread tire according to the first embodiment is obtained by blending a diene rubber with a treated zinc oxide having a nitrogen adsorption specific surface area of 6 m ² / g or more treated with an organic acid. . By using such specific treated zinc oxide, the durability of the retread tire can be improved. The reason is not intended to be limited, but is presumed as follows. That is, the treated zinc oxide has a relatively large nitrogen adsorption specific surface area and a small particle size. Although small particle size zinc oxide is generally difficult to disperse, by treating with an organic acid, the organic acid acts as a lubricant at the time of kneading of the rubber composition, and the small particle size treated zinc oxide is highly advanced in the rubber composition It is considered to be dispersed. In addition, the presence of the organic acid on the surface of the zinc oxide makes it possible to use sulfur of diene rubber in the base tire or tread rubber which is vulcanized rubber and diene rubber in the cushion rubber which is unvulcanized rubber. It is believed that the crosslinkability via the core is greatly improved. Therefore, the adhesion between the cushion rubber and the base tire and the tread rubber can be improved, and the durability of the retread tire can be improved.

  In the cushion rubber composition, examples of the diene rubber compounded as the rubber component include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene-isoprene rubber, A butadiene isoprene rubber, a styrene butadiene isoprene rubber etc. are mentioned, These can be used individually or in mixture of 2 or more types, respectively. Preferably, it is NR, SBR, BR, or a blend of two or more thereof, and in one embodiment, NR alone or a blend of NR 60% by mass or more and SBR and / or BR 40% by mass or less may be used.

  The treated zinc oxide used in the present embodiment is obtained by treating zinc oxide with an organic acid. In general, zinc oxide (zinc white) acts as a vulcanization acceleration assistant to activate the vulcanization accelerator and increase the acceleration reaction in sulfur vulcanization of diene rubber, but in the present embodiment, the action of such zinc oxide is enhanced By previously treating the organic acid to zinc oxide, the action of zinc oxide can be further enhanced. In addition, the organic acid coated on the surface of the zinc oxide powder acts as a lubricant, whereby the dispersibility of the treated zinc oxide having a small particle size can be improved.

As the treated zinc oxide, one having a nitrogen adsorption specific surface area of 6 m ² / g or more as described above is used. While zinc oxide generally used has a nitrogen adsorption specific surface area of about 5 m ² / g or less, in the present embodiment, a small particle size product having a nitrogen adsorption specific surface area of 6 m ² / g or more is used. In combination with the surface treatment with an organic acid, fine dispersion in the rubber composition can be achieved, and the effect of improving the durability of the retread tire can be enhanced. The nitrogen adsorption specific surface area of the treated zinc oxide is preferably 7 m ² / g or more, more preferably 8 m ² / g or more. The upper limit of the nitrogen adsorption specific surface area is not particularly limited, and may be, for example, 50 m ² / g or less. Here, the nitrogen adsorption specific surface area is measured according to JIS K6217-7: 2013.

  As an organic acid used for surface treatment of zinc oxide, aliphatic carboxylic acid is preferable, and aliphatic monocarboxylic acid is more preferable. The aliphatic carboxylic acid may be saturated or unsaturated, and may be linear or branched. The carbon number of the aliphatic carboxylic acid may be 1 to 20, 1 to 16, 2 to 10, or 3 to 8. Preferred specific examples of aliphatic monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, caproic acid, enanthate, caprylic acid, pelargonic acid, capric acid, lauric acid, myristin Acid, palmitic acid, acrylic acid, crotonic acid, isocrotonic acid and the like can be mentioned, and these can be used alone or in combination of two or more. As the organic acid, an aliphatic monocarboxylic acid having 2 to 10 carbon atoms (more preferably, a saturated aliphatic monocarboxylic acid) is preferable, and more preferably the ease of treating zinc oxide and the above-mentioned effects and effects. Is a C3-C8 aliphatic monocarboxylic acid (more preferably, a saturated aliphatic monocarboxylic acid).

  The treated amount of the organic acid in the treated zinc oxide is not particularly limited, but 0.01 to 10% by mass with respect to zinc oxide (that is, 0.01 to 10 parts by mass of the organic acid with respect to 100 parts by mass of zinc oxide) Is preferably 0.05 to 3.0% by mass.

  As such treated zinc oxide, commercially available ones can be used, and zinc oxide coated with an organic acid is used by adding and mixing zinc oxide with an organic acid. May be For example, an ethanol solution of an organic acid is dropped into a water slurry of zinc oxide, and the solution is stirred and then dried.

  In the cushion rubber composition, the content of the treated zinc oxide can be set in the same manner as the general compounding amount of zinc oxide, and specifically, 0.1 parts by weight per 100 parts by weight of diene rubber. The amount is preferably 10 parts by mass, more preferably 1 to 8 parts by mass, and still more preferably 2 to 5 parts by mass.

  In the cushion rubber composition, a filler composed of carbon black and / or silica can be blended. It is preferable to use carbon black as the filler. The carbon black is not particularly limited, and various known types can be used. For example, various furnace blacks such as SAF grade (N 100 series), ISAF grade (N 200 series), HAF grade (N 300 series), FEF grade (N 500 series) (both are ASTM grade) can be used. You may use combining the carbon black of a seed or more. The compounding amount of the filler (preferably carbon black) is not particularly limited, and is preferably 20 to 100 parts by mass, more preferably 30 to 80 parts by mass with respect to 100 parts by mass of the diene rubber. More preferably, it is 30-60 mass parts.

  Cushion rubber compositions generally include, in addition to the above components, stearic acid, anti-aging agents, oils, waxes, tackifiers, vulcanizing agents, vulcanization accelerators, vulcanization retarders, etc., in rubber compositions in general. Various additives used can be blended.

  It does not specifically limit as a compounding quantity of a stearic acid, For example, 0.5-10 mass parts may be sufficient with respect to 100 mass parts of diene based rubbers, and 1-5 mass parts may be sufficient.

  Examples of the vulcanizing agent include sulfur such as powdery sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur and the like, and although not particularly limited, the compounding amount thereof is 100 parts by mass of diene rubber The amount is preferably 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass.

  As a vulcanization accelerator, for example, dibenzothiazolyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), zinc salt of 2-mercaptobenzothiazole (ZnMBT), cyclohexylamine salt of 2-mercaptobenzothiazole (CMBT) ), Thiazole-based vulcanization accelerators such as 2- (4'-morpholinodithio) benzothiazole (MDB), zinc dibenzyldithiocarbamate, zinc dimethyldithiocarbamate (ZnMDC), and dithiocarbamic acids such as zinc diethyldithiocarbamate (ZnEDC) Salt-based vulcanization accelerator, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (BBS), N, N-diisopropyl-2-benzothiazole Sulfenamide-based vulcanization accelerators such as sulfenamide (DPBS), thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrabutylthiuram disulfide (TBTD), 1,3-diphenylguanidine (DPG) Guanidine-based vulcanization accelerators such as 1,3-di-o-tolylguanidine (DOTG), thiourea-based vulcanization accelerations such as N, N'-diphenylthiourea, trimethylthiourea and N, N'-diethylthiourea Agents and the like. These can be used alone or in combination of two or more. Among these, the combined use of a thiazole based vulcanization accelerator, a dithiocarbamate based vulcanization accelerator and a guanidine based vulcanization accelerator is preferable. The compounding amount of the vulcanization accelerator is preferably 0.1 to 7 parts by mass, and more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the diene rubber.

  The cushion rubber composition can be prepared by kneading according to a conventional method using a mixer such as a Banbury mixer, a kneader, or a roll which is usually used.

  The cushion rubber composition is used as a cushion rubber of a retread tire. That is, when the tread surface of a tire which has been worn and has finished its primary life is buffed into a base tire, and the pre-vulcanized tread rubber (precure tread) is attached to the crown portion of the base tire, the rubber composition The unvulcanized sheet-like cushion rubber is interposed between the two, and heated to, for example, 90 to 140 ° C. to vulcanize the cushion rubber, thereby bonding the base tire and the tread rubber. Thereby, the retread tire which concerns on one Embodiment is obtained.

Second Embodiment: Tire inner liner or rubber composition for squeegee
The tire inner liner or the rubber composition for squeegee according to the second embodiment comprises a rubber component mixed with a treated zinc oxide having a nitrogen adsorption specific surface area of 6 m ² / g or more treated with an organic acid. is there.

  In the rubber composition for the inner liner, it is preferable to use butyl-based rubber as the rubber component from the viewpoint of air permeation resistance. Examples of butyl rubber include halogenated butyl rubber such as brominated butyl rubber (BIIR) and chlorinated butyl rubber (CIIR), butyl rubber (IIR) and the like, and these are used alone or in combination of two or more kinds. be able to. The rubber component may be butyl rubber alone or may be a blend of butyl rubber and diene rubber. In that case, preferably 50 parts by mass or more, and more preferably 70 parts by mass or more of the 100 parts by mass of the rubber component is butyl rubber. Examples of the diene-based rubber used in combination with the butyl-based rubber include various diene-based rubbers listed in the first embodiment, and preferred are NR and / or BR.

  In the rubber composition for squeegee, it is preferable to use a diene rubber as the rubber component. Examples of the diene rubber include various diene rubbers listed in the first embodiment, and preferably the rubber component is at least one selected from the group consisting of NR, SBR and BR, more preferably, It is a blend of NR alone or NR 60% by mass or more and SBR and / or BR 40% by mass or less.

As the treated zinc oxide, one having a nitrogen adsorption specific surface area treated with an organic acid of 6 m ² / g or more as in the first embodiment is used. Details of the preferable range of the nitrogen adsorption specific surface area, the specific example of the organic acid, the treatment amount, the treatment method and the like are the same as in the first embodiment, and the description will be omitted. The compounding amount in the rubber composition can be set in the same manner as the general compounding amount of zinc oxide, and specifically, it is 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. Is preferable, and more preferably 1 to 8 parts by mass.

  In the inner liner or the squeegee rubber composition, a filler composed of carbon black and / or silica can be blended. It is preferable to use carbon black as the filler. The blending amount of the filler (preferably carbon black) is not particularly limited, and is preferably 20 to 100 parts by mass, and more preferably 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

  In rubber compositions for inner liners or squeegees, in addition to the above-mentioned components, stearic acid, anti-aging agent, tackifier, sulfur, vulcanization accelerator, vulcanization retarder, etc. are generally used in rubber compositions Additives can be blended. The compounding amount of sulfur is preferably 0.1 to 3 parts by mass, more preferably 0.3 to 2 parts by mass with respect to 100 parts by mass of the rubber component in the case of the rubber composition for the inner liner. In the case of the rubber composition for use, it is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

  The inner liner or the rubber composition for squeegee can be prepared by kneading according to a conventional method using a mixer such as a Banbury mixer, a kneader or a roll which is usually used. The obtained rubber composition can be used as a rubber composition constituting an inner liner and / or a squeegee of a pneumatic tire. For example, an unvulcanized tire formed into a sheet by a roll, an extruder or the like according to a conventional method and pasted the sheet as an inner liner and / or a squeegee to the inside of the carcass ply may be, for example, 130 to By vulcanizing at 160 ° C., a pneumatic tire provided with an inner liner and / or a squeegee made of the above rubber composition can be obtained. Only the inner liner may be formed of the above rubber composition, only the squeegee may be formed of the above rubber composition, and both the inner liner and the squeegee may be formed on the above rubber composition. By using the above-described organic acid-treated zinc oxide having a high nitrogen adsorption specific surface area in both the inner liner and the squeegee, the effect of suppressing the peeling between the inner liner and the carcass ply can be further enhanced. The thickness of the inner liner varies depending on the tire size and the like, but is usually 0.5 to 3.0 mm. The thickness of the squeegee varies depending on the tire size and the like, but is usually 0.5 to 3.0 mm.

  Hereinafter, although the example of the present invention is shown, the present invention is not limited to these examples.

(First embodiment)
Using the Banbury mixer, according to the composition (parts by mass) shown in Table 1 below, first, at the first mixing stage, other compounding agents other than sulfur, vulcanization accelerator and vulcanization retarder are added to the diene rubber And kneaded (discharge temperature = 160.degree. C.), then, at the final mixing stage, sulfur, a vulcanization accelerator and a vulcanization retarder are added to the obtained kneaded product and kneaded (discharge temperature = 90.degree. C.), A cushion rubber composition for retread tire was prepared. However, in Example 4, a part of vulcanization accelerator (vulcanization accelerator 1) is added in the first mixing stage, and the remaining vulcanization accelerators (vulcanization accelerators 2 and 3) are added in the final mixing stage. Added with sulfur and cure retarder. The details of each component in Table 1 are as follows.

Natural rubber: RSS # 3
・ SBR: Nippon Zeon Co., Ltd. "NIPOL 1502"
-Carbon black 1: "Shaw Black N 326" manufactured by Cabot Japan Ltd.
-Carbon black 2: "Shaw Black N330T" manufactured by Cabot Japan Ltd.
-Stearic acid: "Stearic acid" manufactured by NOF Corporation
-Zinc oxide (A): "800" manufactured by Zinc Oxide LLC (nitrogen adsorption specific surface area 5.0 m ² / g, untreated product)
Zinc oxide (B): “800H” manufactured by Zinc Oxide LLC (nitrogen adsorption specific surface area 7.35 m ² / g, untreated product)
-Zinc oxide (C): "ZOCO 172" manufactured by Zochem (nitrogen adsorption specific surface area 4.75 m ² / g, propionic acid-treated product, throughput 0.1 mass%)
-Zinc oxide (D): "Zano 20 Plus ² " manufactured by Yumicore (nitrogen adsorption specific surface area 30 m ² / g, 3-aminopropyltrimethoxysilane-treated product, throughput 0.1 mass%)
-Zinc oxide (E): "800 HT" manufactured by Zinc Oxide LLC (nitrogen adsorption specific surface area 7.35 m ² / g, propionic acid-treated product, throughput 0.1 mass%)
-Zinc oxide (F): "800 HSA-T" manufactured by Zinc Oxide LLC (nitrogen adsorption specific surface area 9.0 m ² / g, propionic acid-treated product, throughput 0.1 mass%)
Zinc oxide (G): Coating treated zinc oxide prepared by treating “800H” manufactured by Zinc Oxide LLC with caproic acid (nitrogen adsorption specific surface area 7.35 m ² / g, throughput 0.1 mass%) (zinc oxide water slurry) Prepared by dropping an ethanol solution of caproic acid dropwise into this slurry and then stirring and drying)
・ Anti-aging agent: Ouchi Shinko Chemical Co., Ltd. product "Nocrac 6C"
Oil: JX Nippon Oil & Energy "Process P200"
-Tackifier: "Escollets 1102" manufactured by Exxon Mobil
Sulfur 1: Powdered sulfur from Tsurumi Chemical Industries, Ltd.
・ Vulcanization accelerator 1: Noccellar D manufactured by Ouchi Shinko Chemical Co., Ltd.
・ Vulcanization accelerator 2: "Noxceller M" manufactured by Ouchi Shinko Chemical Co., Ltd.
・ Vulcanization accelerator 3: "Noxceler ZTC" manufactured by Ouchi Shinko Chemical Co., Ltd.
・ Vulcanization retarder: Lancess "Bull Current E / C"

  The durability of the retread tire using each rubber composition obtained as a cushion rubber was evaluated. In detail, after attaching an unvulcanized cushion rubber sheet having a thickness of 1.5 mm to the precured tread, it is left at room temperature for a week, and then attached to a base tire of tire size 11R22.5, and then The cured rubber was manufactured by vulcanizing the cushion rubber. Step of attaching the obtained retread tire to a standard rim and grounding it to an indoor drum tester, and increasing the speed by 10 km / h every hour from 40 km / h under the conditions of air pressure and load specified by JATMA. The distance traveled until it broke under the up condition was measured. The value of Comparative Example 1 is represented by an index of 100. The larger the index, the longer the travel distance and the higher the durability. When the index is 105 or more, the effect of improving the durability is recognized.

  The results are as shown in Table 1. Compared to Comparative Example 1 which is a control using zinc oxide having a general nitrogen adsorption specific surface area, in Comparative Example 2 using a zinc oxide which is an untreated product although the nitrogen adsorption specific surface area is large, the effect of improving the durability Was inadequate. In Comparative Example 3, the treated zinc oxide treated with an organic acid was used, but since the nitrogen adsorption specific surface area was small, the effect of improving the durability was small. In Comparative Example 4, a treated zinc oxide having a large nitrogen adsorption specific surface area was used, but since it was a treated product with an organic silane compound, the effect of improving the durability was small. From this, it is considered that the improvement effect of the durability is not sufficient only by simply improving the dispersibility of the small particle size zinc oxide. On the other hand, in Examples 1 to 4 using organic acid-treated zinc oxide having a large nitrogen adsorption specific surface area, the durability was significantly improved. In addition, as shown in Comparative Example 5, when the propionic acid is mixed with zinc oxide in the first mixing step without being previously treated with zinc oxide, the remarkable improvement in durability as in Example 1 is obtained. Was not obtained.

Second Embodiment
A rubber composition for a tire inner liner and a rubber composition for a squeegee were prepared according to the composition (parts by mass) shown in Table 2 below using a Banbury mixer. The details of each component in Table 2 are as follows (the same as described in Table 1 is as described above).

-BIIR: Brominated butyl rubber, "Bromobutyl 2222" manufactured by ExxonMobil
・ Carbon black 3: GPF, "Siest V" manufactured by Tokai Carbon Co., Ltd.
・ Vulcanization accelerator 4: "Noxceler DM-P" manufactured by Ouchi Shinko Chemical Co., Ltd.
・ Vulcanization accelerator 5: "Noxceler DZ-G" manufactured by Ouchi Shinko Chemical Co., Ltd.
・ Sulfur 2: Muxlon HS OT-20 (20% oil) manufactured by Flexis.

  Using each of the obtained rubber compositions, a heavy load pneumatic tire (tire size: 11R22.5) was prototyped. In detail, after forming the inner liner rubber into a sheet with a thickness of 2 mm and the squeegee rubber with a thickness of 2 mm, an unvulcanized tire was produced in which the both were attached to the inside of the carcass ply. . All configurations except for the inner liner and the squeegee were common. Step up by assembling the obtained prototype tire on a standard rim and grounding it to an indoor drum tester and increasing the speed by 10 km / h every hour from 40 km / h under the conditions of air pressure and load specified by JATMA The distance traveled until it broke under the conditions was measured. Comparative Example 6 is represented by an index of 100. The larger the number, the longer the travel distance and the higher the durability. When the index is 105 or more, the effect of improving the durability is recognized.

  The results are as shown in Table 2. In contrast to Comparative Example 6 which is a control using zinc oxide having a general nitrogen adsorption specific surface area for both the inner liner and the squeegee, a comparative example using zinc oxide which is an untreated product although the nitrogen adsorption specific surface area is large In No. 7, the effect of improving the durability was insufficient. In Comparative Example 8, a treated zinc oxide treated with an organic acid was used for the inner liner, but since the nitrogen adsorption specific surface area was small, the effect of improving the durability was small. In Comparative Example 9, a treated zinc oxide having a large nitrogen adsorption specific surface area was used for the inner liner, but since it was a treated article with an organic silane compound, the effect of improving the durability was small. On the other hand, in Examples 5 to 10 in which organic acid-treated zinc oxide having a large nitrogen adsorption specific surface area was used as the inner liner and / or squeegee, the durability was significantly improved. In particular, in Example 8 in which organic acid-treated zinc oxide having a large nitrogen adsorption specific surface area was used for both the inner liner and the squeegee, the durability was remarkably improved.

Claims (4)

A treated zinc oxide which is treated with an aliphatic monocarboxylic acid having 2 to 10 carbon atoms and which has a nitrogen adsorption specific surface area of 6 m ² / g or more based on 100 parts by mass of a diene rubber is aliphatic with respect to 100 parts by mass of zinc oxide The cushion rubber composition for retread tires which contains 0.1-10 mass parts of processing zinc oxides which are 0.01-10 mass parts of processing amounts of monocarboxylic acid . A retread tire characterized in that the cushion rubber composition according to claim 1 is used as a cushion rubber interposed between a base tire and a tread rubber to bond the two. A treated zinc oxide which is treated with an aliphatic monocarboxylic acid having 2 to 10 carbon atoms and which has a nitrogen adsorption specific surface area of 6 m ² / g or more per 100 parts by mass of a rubber component is an aliphatic mono with respect to 100 parts by mass of zinc oxide A tire inner liner or a rubber composition for squeegee, comprising 0.1 to 10 parts by mass of a treated zinc oxide having a treated amount of carboxylic acid of 0.01 to 10 parts by mass. A pneumatic tire using the rubber composition according to claim 3 for an inner liner and / or a squeegee.