PNEUMATIC TIRE

Abstract

The present invention provides a pneumatic tire that can improve wet grip performance while maintaining a good TGC resistance, even when the tire is stored as having a thin thickness of a subtread at a bottom of a tread main groove, and rim-assembled and mounted on a vehicle to be left to stand. The present invention relates to a pneumatic tire comprising a tread part, the tread part comprising at least a cap tread and a jointless band, the cap tread being formed of a rubber composition for a cap tread, the jointless band comprising fiber cords coated with a rubber composition for fiber cord toppings, the rubber composition for a cap tread comprising 3.0 parts by mass or more of antioxidant based on 100 parts by mass of a rubber component comprising a diene-based rubber, and wherein a subtread thickness at the bottom of tread main grooves is 0.1 to 3.0 mm

Claims

1. A pneumatic tire comprising a tread part, the tread part comprising at least a cap tread and a jointless band, the cap tread being formed of a rubber composition for a cap tread, the jointless band comprising fiber cords coated with a rubber composition for fiber cord toppings, the rubber composition for a cap tread comprising 3.0 parts by mass or more of antioxidant based on 100 parts by mass of a rubber component comprising a diene-based rubber, wherein a subtread thickness at the bottom of tread main grooves is 0.1 to 3.0 mm.

2. The pneumatic tire of claim 1, wherein the rubber composition for a cap tread comprises 0.10 to 6.0 parts by mass of surfactant having a HLB of 5 to 12 and/or C.sub.40-70 branched alkane based on 100 parts by mass of the rubber component.

3. The pneumatic tire of claim 1, wherein the rubber composition for a cap tread comprises a bisphenol-based antioxidant.

4. The pneumatic tire of claim 1, wherein the rubber composition for a cap tread comprises two or more selected from the group consisting of a phenylenediamine-based antioxidant, a bisphenol-based antioxidant, and a quinoline-based antioxidant.

5. The pneumatic tire of claim 1, wherein the rubber composition for a cap tread comprises 3.0 parts by mass or more of phenylenediamine-based antioxidant and/or bisphenol-based antioxidant based on 100 parts by mass of the rubber component.

6. The pneumatic tire of claim 1, wherein the rubber composition for a cap tread comprises 3.1 parts by mass or more of phenylenediamine-based antioxidant and quinoline-based antioxidant based on 100 parts by mass of the rubber component.

7. The pneumatic tire of claim 1, wherein the rubber composition for fiber cord toppings substantially does not comprise a phenylenediamine-based antioxidant and a bisphenol-based antioxidant.

Description

EXAMPLE

[0132] Although the present invention will be described based on examples, it is not limited to the examples only.

[0133] Various chemicals used in Examples and Comparative examples are shown below.

[0134] SBR1: N9548 manufactured by Zeon Corporation (styrene content: 35% by mass, vinyl content: 35% by mass, Mw: 1,090,000, oil-extended in a content of 37.5 parts by mass based on 100 parts by mass of a rubber component)

[0135] SBR2: NS612 manufactured by Zeon Corporation (styrene content: 15% by mass, vinyl content: 30% by mass, Mw: 780,000, not oil-extended)

[0136] BR: CB25 manufactured by LANXESS (BR synthesized using a neodymium (Nd) based catalyst (Nd-BR), cis content: 97% by mass, vinyl content: 0.7% by mass, Mw: 500,000)

[0137] Carbon black 1: Show Black N351H manufactured by Cabot Japan K.K. (N.sub.2SA: 69 m.sup.2/g)

[0138] Carbon black 2: Show Black N220 manufactured by Cabot Japan K.K. (N.sub.2SA: 111 m.sup.2/g)

[0139] Silica: ULTRASIL VN3 manufactured by Evonik Degussa GmbH (N.sub.2SA: 175 m.sup.2/g)

[0140] Silane coupling agent 1: Si75 manufactured by Evonik Degussa GmbH (bis(3-triethoxysilylpropyl)disulfide)

[0141] Silane coupling agent 2: NXT-Z45 manufactured by Momentive Performance Materials (silane coupling agent having a mercapto group)

[0142] Adhesive resin 1: Sylvatraxx 4401 manufactured by Arizona Chemical Company (α-methylstyrene resin, softening point: 85° C., Tg: 43° C., SP value: 9.1, Mw: 700)

[0143] Adhesive resin 2: YS resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (terpene styrene resin, softening point: 125° C., Tg: 64° C., SP value: 8.7, Mw: 800)

[0144] Adhesive resin 3: NOVARES C10 manufactured by Ruetgers Chemicals (liquid cumarone indene resin, softening point: 10° C., Tg: −30° C., SP value: 8.8, Mw: 350)

[0145] Surfactant 1: STRUKTOL WB16 manufactured by Schill+Seilacher GmbH (mixture of a fatty acid ester and a fatty acid metal salt, HLB: 8.3, SP value: 10.0)

[0146] Surfactant 2: NEWPOL PE-64 manufactured by Sanyo Chemical Industries, Ltd. (pluronic nonionic surfactant, HLB: 10.9, SP value: 9.2)

[0147] Surfactant 3: PEG4000N manufactured by Sanyo Chemical Industries, Ltd. (polyethylene glycol, HLB: 19.5, SP value: 9.6)

[0148] Surfactant 4: Stearic acid “Camellia” manufactured by NOF CORPORATION (HLB: 4.2, SP value: 9.1)

[0149] Wax 1: OZOACE 355 manufactured by Nippon Seiro Co., Ltd. (paraffin wax, branched alkane of 40 to 70 carbon atoms: 8.3% by mass, melting point: 70° C.)

[0150] Wax 2: Hi-Mic 1080 manufactured by Nippon Seiro Co., Ltd. (microcrystalline wax, branched alkane of 40 to 70 carbon atoms: 47.0% by mass, melting point: 84° C.)

[0151] Oil 1: VivaTec 500 manufactured by H & R Group (TDAE oil)

[0152] Oil 2: Diana process AH-24 manufactured by Idemitsu Kosan Co., Ltd. (aroma-based process oil)

[0153] Phenylenediamine-based antioxidant 1: Vulkanox 4020 manufactured by LANXESS (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD))

[0154] Phenylenediamine-based antioxidant 2: Vulkanox 4030 manufactured by LANXESS (N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD))

[0155] Phenylenediamine-based antioxidant 3: Vulkanox DPPD manufactured by LANXESS (N,N′-diphenyl-p-phenylenediamine (DPPD))

[0156] Bisphenol-based antioxidant 1: NS-6 manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (2,2′-methylenebis(4-methyl-6-tert-butylphenol))

[0157] Bisphenol-based antioxidant 2: NS-30 manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (4,4′-butylidebis(3-methyl-6-tert-butylphenol))

[0158] Quinoline-based antioxidant: Nocrac 224 manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMQ))

[0159] Zinc oxide 1: Ginrei R manufactured by Toho Zinc Co., Ltd.

[0160] Zinc oxide 2: Zinc flower No. 2 manufactured by Mitsui Mining & Smelting Co., Ltd.

[0161] SUMIKANOL 620: SUMIKANOL 620 manufactured by Taoka Chemical Co., Ltd. (modified resorcinol resin (modified resorcinol/formaldehyde condensate))

[0162] SUMIKANOL 507A: SUMIKANOL 507A manufactured by Sumitomo Chemical Co., Ltd. (modified etherified methylolmelamine resin (partial condensate of hexamethylolmelamine pentamethyl ether (HMMPME)), comprising 35% by mass of silica and oil)

[0163] Stearic acid: Stearic acid “Camellia” manufactured by NOF CORPORATION

[0164] Sulfur 1: insoluble sulfur comprising 10% of oil: Seimi sulfur manufactured by Nippon Kanryu Industry Co., Ltd. (insoluble sulfur having 60% or more insolubles derived from carbon disulfide, oil content: 10% by mass)

[0165] Sulfur 2: HK-200-5 manufactured by Hosoi Chemical Industry Co., Ltd. (powdered sulfur comprising 5% by mass of oil)

[0166] Vulcanization accelerator 1: Nocceler NS manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (N-tert-butyl-2-benzothiazolyl sulfeneamide (TBBS))

[0167] Vulcanization accelerator 2: Nocceler D manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (diphenylguanidine (DPG))

EXAMPLES AND COMPARATIVE EXAMPLES

[0168] According to the compounding formulations shown in Tables 1 to 3, using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., all chemicals other than sulfur and vulcanization accelerators were kneaded. Next, sulfur and vulcanization accelerators were added to the obtained kneaded product and then kneaded using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was used to be molded into a shape of a cap tread and a jointless band, attached together with other tire members to prepare an unvulcanized tire, and vulcanized at 170° C. to obtain a test tire (205/65R15, 8.7 kg). Besides, the test tire was prepared with a tread pattern of a five-main groove structure, a subtread structure being subject to the specifications shown in Tables 2 and 3, and nylon 6,6 (1400d-tex/2, cord diameter: 0.54 mm) manufactured by Asahi Kasei Corporation being used as a fiber cord. Performance of the obtained test tire was evaluated by the following test.

<Processability Test>

[0169] For each unvulcanized JLB rubber composition (Compounding 1 and Compounding 2), a rubber sheet was pressure-bonded to a fiber cord fabric (diameter: 1.7 m) with a roll, wound up, and then cut into a tape shape of 10 cords. The appearance was visually inspected, and a minor defect rate was determined with those having no take-off and tear-off of a rubber and rubber burning being regarded as quality products. The inverse values of the obtained minor defect rate were expressed as indexes as Compounding 1 being 100. The results show that the larger the index is, the lower the defect rate is.

<Wet Grip Performance>

[0170] Each test tire was mounted to all wheels of an actual test vehicle (domestic FF vehicle, displacement: 2000 cc), and a braking distance from an initial speed of 100 km/h on a wet road surface was measured. It was expressed as an index as Comparative example 1 being 100 by the following equation. The results show that the larger the index is, the better the wet grip performance is. A performance target value shall be 100 or more, preferably 105 or more.

(Wet grip performance index)=(braking distance of tire in Comparative example 1)/(braking distance of each test tire)×100

<TGC Resistance>

[0171] For the obtained test tires, 12 tires were stacked horizontally in a warehouse in the Osaka area and stored for 3 months. Due to the total weight of the upper tires (as an actual load, a load of 8.7 kg×11 tires is transmitted from the upper tires), ozone cracks become likely to occur at the bottom of the main groove of the lower tire, and thus after the storage for 3 months, a degree of TGC occurrence in the main groove of the bottom tire, which is deformed the most, was observed, and it was expressed as an index as the result of Comparative example 1 being 100. The results show that the larger the index is, the higher the TGC resistance is, and the better the TGC can be suppressed. A performance target value shall be 100 or more.

TABLE-US-00001 TABLE 1 Compounding amount JLB compounding kind (part by mass) Compounding 1 Compounding 2 NR 70 70 SBR 30 30 Carbon black 1 45 45 Phenylenediamine-based antioxidant 1 — 1.0 Quinoline-based antioxidant 2.0 2.0 Zinc oxide 1 7.0 7.0 SUMIKANOL 620 1.0 1.0 Stearic acid 3.0 3.0 SUMIKANOL 507A 1.5 1.5 Sulfur 1 3.75 3.75 Vulcanization accelerator 1 1.0 1.0 Processability of JLB rubber 100 90

TABLE-US-00002 TABLE 2 Example 1 2 3 4 5 6 7 8 9 10 Compounding amount (part by mass) SBR 1 41.25 41.25 41.25 41.25 41.25 41.25 41.25 41.25 41.25 41.25 SBR 2 50 50 50 50 50 50 50 50 50 50 BR 20 20 20 20 20 20 20 20 20 20 Carbon black 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Silica 100 100 100 100 100 100 100 100 100 100 Silane coupling agent 1 8.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 Silane coupling agent 2 — — — — — — — — — — Adhesive resin 1 10 10 10 10 10 10 10 10 10 10 Adhesive resin 2 — — — — — — — — — — Adhesive resin 3 — — — — — — — — — — Surfactant 1 2.0 2.0 2.0 2.0 2.0 2.0 — — 2.0 — Surfactant 2 — — — — — — 2.0 — — — Surfactant 3 — — — — — — — 2.0 — — Wax 1 1.76 1.76 1.76 1.76 1.76 1.76 1.76 1.76 1.76 0.76 Wax 2 — — — — — — — — — 1.00 (C.sub.40-70 branched alkane 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.53 contained in the above wax) Phenylenediamine-based 4.0 8.0 4.0 4.0 — 6.0 4.0 4.0 8.0 4.0 antioxidant 1 Phenylenediamine-based — — — — 4.0 — — — — — antioxidant 2 Phenylenediamine-based — — — — — — — — — — antioxidant 3 Bisphenol-based — — — 4.0 — — — — — — antioxidant 1 Bisphenol-based 4.0 8.0 4.0 — 4.0 — 4.0 4.0 8.0 4.0 antioxidant 2 Quinoline-based 1.0 1.0 1.0 1.0 1.0 3.0 1.0 1.0 1.0 1.0 antioxidant Stearic acid 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Process oil 14 6.0 14 14 14 14 14 14 6.0 14 Zinc oxide 2 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Sulfur 2 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Vulcanization accelerator 1 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 Vulcanization accelerator 2 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 JLB compounding kind 1 1 1 1 1 1 1 1 1 1 Subtread gauge (mm) 2.0 2.0 0.5 2.0 2.0 2.0 2.0 2.0 0.5 2.0 Index Wet grip performance 115 125 120 110 110 111 114 113 130 120 TGC resistance 115 125 105 108 112 114 120 119 105 115 Example 11 12 13 14 15 16 17 18 19 Compounding amount (part by mass) SBR 1 41.25 41.25 41.25 41.25 41.25 41.25 41.25 41.25 41.25 SBR 2 50 50 50 50 50 50 50 50 50 BR 20 20 20 20 20 20 20 20 20 Carbon black 5.0 5.0 5.0 5.0 5.0 5.0 5.0 19 5.0 Silica 100 100 100 120 120 120 100 80 100 Silane coupling agent 1 8.0 8.0 — 9.6 9.6 9.6 8.0 6.4 8.0 Silane coupling agent 2 — — 8.0 — — — — — — Adhesive resin 1 10 — 10 10 10 10 10 10 10 Adhesive resin 2 — — — — — — — — 10 Adhesive resin 3 — 20 — — — — — — — Surfactant 1 — 2.0 2.0 — — 1.0 2.0 2.0 2.0 Surfactant 2 — — — — — — — — — Surfactant 3 — — — — — — — — — Wax 1 — 1.76 1.76 0.76 0.76 0.76 1.76 0.76 1.76 Wax 2 1.00 — — 1.00 1.00 1.00 — 1.00 — (C.sub.40-70 branched alkane 0.47 0.15 0.15 0.53 0.53 0.53 0.15 0.53 0.15 contained in the above wax) Phenylenediamine-based 4.0 4.0 4.0 4.0 8.0 3.0 4.0 8.0 2.0 antioxidant 1 Phenylenediamine-based — — — — — — — — — antioxidant 2 Phenylenediamine-based 2.0 — — — — — — — — antioxidant 3 Bisphenol-based — — — — — — — — — antioxidant 1 Bisphenol-based 4.0 4.0 4.0 4.0 8.0 — 4.0 8.0 — antioxidant 2 Quinoline-based 1.0 1.0 1.0 1.0 1.0 — 1.0 1.0 1.0 antioxidant Stearic acid 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Process oil 14 4.0 14 30 22 30 14 6.0 10 Zinc oxide 2 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Sulfur 2 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Vulcanization accelerator 1 1.3 1.3 2.4 1.3 1.3 1.3 1.3 1.3 1.3 Vulcanization accelerator 2 2.5 2.5 — 2.5 2.5 2.5 2.5 2.5 2.5 JLB compounding kind 1 1 1 1 1 1 2 1 1 Subtread gauge (mm) 2.0 2.0 2.0 2.0 0.5 2.0 2.0 2.0 2.0 Index Wet grip performance 120 120 119 134 150 120 113 110 108 TGC resistance 115 115 117 111 120 105 118 115 102

TABLE-US-00003 TABLE 3 Comparative example 1 2 3 4 5 6 Compounding amount (part by mass) SBR 1 41.25 41.25 41.25 41.25 41.25 41.25 SBR 2 50 50 50 50 50 50 BR 20 20 20 20 20 20 Carbon black 5.0 5.0 5.0 19 19 5.0 Silica 100 100 100 80 80 80 Silane coupling agent 1 8.0 8.0 8.0 6.4 6.4 6.4 Silane coupling agent 2 — — — — — — Adhesive resin 1 10 10 10 10 10 10 Adhesive resin 2 Adhesive resin 3 Surfactant 1 2.0 2.0 2.0 2.0 2.0 2.0 Surfactant 2 — — — — — — Surfactant 3 — — — — — — Wax 1 1.76 1.76 1.76 1.76 1.76 1.76 Wax 2 — — — — — — (C.sub.40-70 branched alkane 0.15 0.15 0.15 0.15 0.15 0.15 contained in the above wax) Phenylenediamine-based 2.0 4.0 2.0 8.0 2.0 2.0 antioxidant 1 Phenylenediamine-based — — — — — — antioxidant 2 Phenylenediamine-based — — — — — — antioxidant 3 Bisphenol-based — — — — — — antioxidant 1 Bisphenol-based — 4.0 — 8.0 — — antioxidant 2 Quinoline -based 1.0 1.0 1.0 1.0 1.0 1.0 antioxidant Stearic acid 3.0 3.0 3.0 3.0 3.0 3.0 Process oil 20 14 20 6.0 20 6.0 Zinc oxide 2 2.0 2.0 2.0 2.0 2.0 2.0 Sulfur 2 1.5 1.5 1.5 1.5 1.5 1.5 Vulcanization accelerator 1 1.3 1.3 1.3 1.3 1.3 1.3 Vulcanization accelerator 2 2.5 2.5 2.5 2.5 2.5 2.5 JLB compounding kind 1 1 1 1 1 1 Subtread gauge (mm) 2.0 4.0 0.5 0 2.0 2.0 Index Wet grip performance 100 99 110 130 90 85 TGC resistance 100 125 80 95 106 106

[0172] From the results in Tables 1 to 3, it can be found that the pneumatic tire of the present invention, in which a predetermined amount of antioxidant was compounded to the rubber composition for a cap tread and a subtread thickness at the bottom of tread main grooves was set to be 0.1 to 3.0 mm, has good TGC resistance and wet grip performance.