JP4762071B2 - Tires that can suppress noise - Google Patents

Description

  The present invention relates to a tire capable of suppressing noise.

  Tires are required to have various characteristics. In particular, as a part of improving the global environment, development of fuel-efficient tires with reduced tire rolling resistance is strongly demanded.

  In order to reduce tire weight and suppress heat generation, this low fuel consumption tire is designed with a thin thickness for each part of the tire, and the rubber material used is a relatively soft rubber compound from the viewpoint of durability and heat generation. Things are used. As a result, there is a problem that road noise cannot be suppressed.

  Conventionally, as a technique for suppressing road noise, for example, (A) a technique of increasing the restraining force of a breaker to suppress vibration of a steel cord, and (B) a technique of restraining with a band to suppress vibration of the steel cord. , (C) a method of increasing the tread gauge to improve cushioning, (D) a method of increasing the loss tangent tan δ of the tread to absorb vibration, and (E) a sponge on the tire inner surface to absorb vibration And (F) a method of sticking a sealant material to the tire inner surface in order to absorb vibration.

  However, when the methods (C), (D), (E), and (F) are used, there is a problem that rolling resistance increases. In addition, the tire weight increases and cannot be adopted from an economical viewpoint.

  Further, when the methods (A) and (B) are used, there is a problem that stress is concentrated on the cut end of the steel cord and durability is lowered.

  In addition, a technique is known in which a reinforcing layer having a predetermined shape and made of rubber having a predetermined range of tan δ and hardness is inserted in the sidewall portion (see, for example, Patent Document 1). However, there is still room for improvement in terms of an increase in tire weight, difficulty in obtaining a uniform vulcanized shape, and deterioration in uniformity.

Japanese Patent Laid-Open No. 2002-301912

  An object of the present invention is to provide a tire capable of suppressing noise while maintaining rolling resistance and durability.

  In the present invention, the JIS-A hardness measured at 23 ° C. is 40 to 65 between the breaker and the inner liner, measured at a temperature of 10 ° C., a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ± 2%. It is related with the tire which has a rubber layer which consists of a rubber composition whose loss tangent is 0.04-1.20, and whose thickness is 0.8-4.0 mm.

  According to the present invention, by having a rubber layer having a predetermined hardness, loss tangent and thickness between the breaker and the inner liner, noise can be suppressed while maintaining rolling resistance and durability. Tires can be provided.

  The tire of the present invention has a rubber layer.

  The rubber layer is preferably made of a rubber composition containing a rubber component and carbon black.

  The rubber component is not particularly limited as long as it is used for the purpose of reducing noise. For example, styrene butadiene rubber (SBR), butyl rubber (IIR), 3,4-isoprene rubber (3,4-IR) ) Etc. These rubber components may be used alone or in combination of two or more. Among these, SBR is preferable because it is excellent in breaking strength and adhesiveness with an adjacent rubber member.

  The glass transition temperature (Tg) of the rubber component is preferably −15 ° C. or higher. When the Tg of the rubber component is less than −15 ° C., tan δ is small and the noise suppressing effect tends to be small. The Tg of the rubber component is preferably 15 ° C. or lower, and more preferably 10 ° C. or lower. If the Tg of the rubber component exceeds 15 ° C., the winter hardness (Hs) is too high, so that it tends to be inferior in durability even when used in a temperate region.

  In the present invention, it is preferable to contain ultrafine carbon black.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 170 m ² / g or more, and more preferably 180 m ² / g or more. If N ₂ SA of carbon black is less than 170 m ² / g, it tends to be difficult to increase tan δ while keeping Hs within a predetermined range. Also, N ₂ SA of the carbon black is preferably at most 380m ² / g, more preferably at most 350m ² / g. If the N ₂ SA of the carbon black exceeds 380 m ² / g, the carbon black tends to be too fine and the rubber component and carbon black tend to be poorly dispersed and mixed.

  The dibutyl phthalate oil absorption (DBP) of carbon black is preferably 115 ml / 100 g or more, and more preferably 120 ml / 100 g or more. When the DBP of carbon black is less than 115 ml / 100 g, Hs tends to be small and the breaking strength tends to be low. The DBP of carbon black is preferably 190 ml / 100 g or less, more preferably 170 ml / 100 g or less. When the DBP of carbon black exceeds 190 ml / 100 g, the structure is too high and the rubber component and carbon black tend to be poorly dispersed and mixed.

  The content of carbon black is preferably 30 parts by weight or more and more preferably 35 parts by weight or more with respect to 100 parts by weight of the rubber component. If the carbon black content is less than 30 parts by weight, the processability of raw rubber dough before vulcanization is poor, and there is a tendency that sufficient Hs cannot be obtained. The carbon black content is preferably 60 parts by weight or less, more preferably 55 parts by weight or less. If the carbon black content exceeds 60 parts by weight, tan δ can be sufficiently increased, but Hs tends to be too high.

  In addition to the rubber component and carbon black, the rubber composition used in the rubber layer in the present invention is a compounding agent that is usually blended in the tire industry, such as zinc oxide. Stearic acid, various anti-aging agents, wax, tackifying resin, aroma oil, sulfur and other vulcanizing agents, various vulcanization accelerators, and the like can be appropriately blended as necessary.

  The JIS-A hardness at 23 ° C. of the rubber composition used for the rubber layer in the present invention is 40 or more, preferably 42 or more. When the JIS-A hardness of the rubber composition is less than 40, there is a problem in durability, and it cannot be set to a thickness effective in suppressing noise. The rubber composition has a JIS-A hardness of 65 or less, preferably 63 or less. If the JIS-A hardness of the rubber composition exceeds 65, a sufficient effect of suppressing noise cannot be obtained.

  The loss tangent (tan δ) measured at a temperature of 10 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of ± 2% of the rubber composition used in the rubber layer in the present invention is 0.04 or more, preferably 0.40 or more. More preferably, it is 0.50. When the tan δ of the rubber composition is less than 0.04, a sufficient effect of suppressing noise cannot be obtained. The tan δ of the rubber composition is 1.20 or less, preferably 1.10 or less. When the tan δ of the rubber composition exceeds 1.20, there is a problem in durability in a cold region.

  The thickness of the rubber layer used in the present invention is 0.8 mm or more, preferably 1.0 mm or more. If the thickness of the rubber layer is less than 0.8 mm, a sufficient noise reduction effect cannot be obtained. The rubber layer has a thickness of 4.0 mm or less, preferably 3.0 mm or less. When the thickness of the rubber layer exceeds 4.0 mm, the tire weight increases, so that rolling resistance and high-speed durability are deteriorated.

  The width of the rubber layer used in the present invention is preferably 0.5 times or more, more preferably 0.6 times or more the width of the breaker. When the width of the rubber layer is less than 0.5 times the width of the breaker, there is a tendency that a sufficient noise reduction effect cannot be obtained. The width of the rubber layer is preferably 2.0 times or less, more preferably 1.8 times or less the width of the breaker. When the width of the rubber layer exceeds 2.0 times the width of the breaker, the noise reduction effect tends to be small although the rolling resistance increases due to an increase in tire weight. In particular, when the width of the rubber layer is so long that the rubber layer reaches the bead, the rolling resistance is remarkably increased.

  FIG. 1 is a cross-sectional explanatory view of a tire for explaining an insertion position of a rubber layer used in the tire of the present invention.

  Referring to FIG. 1, in the tire of the present invention, the rubber layer is a layer inserted between the first breaker 2 and the inner liner 4.

  The layer between the first breaker 2 and the inner liner 4 refers to the first breaker / carcass layer C or the carcass / inner liner layer D.

  By making the rubber layer the layer C between the first breaker / carcass or the layer D between the carcass / inner liner, the rolling resistance can be maintained despite the insertion of the rubber layer having a large tan δ, , Noise can be suppressed.

  When the rubber layer is formed on the first breaker 2, that is, the base tread A or the layer B between the first breaker and the second breaker, the high speed durability is remarkably deteriorated.

  Further, when the rubber layer is the inner layer E of the inner liner 4, the rubber layer is deteriorated by air oxidation.

  The pneumatic tire of the present invention is manufactured by a normal method by applying the rubber layer to the first breaker / carcass C or the carcass / inner liner D. That is, the rubber composition of the present invention blended with various compounding agents as necessary is extruded into a predetermined shape in an unvulcanized stage, and molded by a normal method on a tire molding machine, Bonding together with other tire members forms an unvulcanized tire. Then, the tire of this invention can be manufactured by heat-pressing in a vulcanizer.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Solution-polymerized styrene butadiene rubber (S-SBR): SE8529 manufactured by Sumitomo Chemical Co., Ltd. (Coupled with SiCl ₄ , Tg: −13 ° C., tan δ peak temperature: 2 ° C., Mw: 950,000, styrene content: 40 weight) %, Vinyl bond content: 51% by weight, containing 44 parts by weight of oil (aromatic oil) per 100 parts by weight of rubber solid content)
Natural rubber (NR): RSS # 3 (Tg: -73 ° C)
Butadiene rubber (BR): BR150B manufactured by Ube Industries, Ltd. (Tg: -100 ° C)
Carbon black (1): HPT6 (N ₂ SA: 183 m ² / g, DBP: 123 ml / 100 g) manufactured by Cabot Japan
Carbon Black (2): Show Black N330 (N ₂ SA: 79 m ² / g, DBP: 102 ml / 100 g) manufactured by Cabot Japan
Zinc oxide: Zinc Hana No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stearic acid “Kun” manufactured by Nippon Oil & Fats Co., Ltd.
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Wax: Sunnock wax tackifying resin manufactured by Ouchi Shinsei Chemical Industry Co., Ltd .: SP1068 manufactured by Nippon Shokubai Co., Ltd.
Insoluble sulfur: Kristex OT10 manufactured by Flexis (pure sulfur content: 90% by weight, oil content 10% by weight)
Vulcanization accelerator CZ: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator DPG: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

Production Examples 1 to 5 (Production of rubber compositions 1 to 5)
According to the formulation shown in Table 1, various chemicals other than sulfur and a vulcanization accelerator were kneaded using a Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded material, and kneaded using an open roll to obtain an unvulcanized rubber composition. Furthermore, the obtained unvulcanized rubber composition was press-vulcanized for 12 minutes under the condition of 170 ° C. to produce rubber compositions 1 to 5. In Table 1, the content of S-SBR indicates the content including oil.

(Rubber hardness)
Based on JIS K 6253 “Method for testing hardness of vulcanized rubber and thermoplastic rubber”, the hardness (Hs) of the rubber specimen was measured using a type A durometer.

(Viscoelasticity test)
Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho, loss tangent tan δ at 10 ° C. was measured under conditions of a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ± 2%.

  Table 1 shows the rubber physical properties of the rubber compositions 1 to 5.

Examples 1-6 and Comparative Examples 1-10
The unvulcanized rubber composition is molded into the thickness and width shown in Table 2, applied to the insertion position shown in Table 2, and bonded together with other tire members, and press vulcanized at 185 ° C. for 10 minutes. The test summer tires (size: 195 / 65R15) of Examples 1 to 6 and Comparative Examples 1 to 10 were manufactured. In the width of rubber, 1 indicates the same width as the breaker, and 1/2 indicates a width that is 1/2 of the breaker. The term “up to bead” indicates that the inserted rubber layer reaches the bead.

(Noise interior sound)
The manufactured test summer tire was mounted on a test vehicle (Toyota Wish (WISH)), and the vehicle was driven on a smooth road surface at a speed of 50 km / h. . And the noise level of each composition was evaluated based on the noise level of Comparative Example 10. In addition, dB (A) indicates that the noise can be suppressed to ½ in the case of −3 dB (A), and that the noise can be suppressed to ¼ in the case of −6 dB (A). Show.

(Rolling resistance)
Using a rolling resistance tester, rolling resistance was measured when the test tire was run at a speed of 80 km / h under conditions of a rim of 15 × 6 JJ, an internal pressure of 200 kPa, and a load of 4 kN. And the rolling resistance of each formulation was corrected using the fact that the rolling resistance is proportional to the weight of the tire. Furthermore, the rolling resistance index of Comparative Example 10 was taken as 100, and the rolling resistance correction value for each formulation was displayed as an index. In addition, it shows that rolling resistance can be reduced and it is so favorable that a rolling resistance index | exponent is small.

  The evaluation results are shown in Table 2.

It is a section explanatory view of a tire for explaining an insertion position of a rubber layer used in a tire of the present invention.

Explanation of symbols

1 Second breaker 2 First breaker 3 Carcass 4 Inner liner A Base tread B Layer between first breaker / second breaker C Layer between first breaker / carcass D Layer between carcass / inner liner E Inside inner liner layer

Claims (3)

Between the breaker and the inner liner,
JIS-A hardness measured at 23 ° C. is 40 to 65,
A rubber composition having a loss tangent of 0.40 to 1.20 measured at a temperature of 10 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of ± 2%,
Thickness have a rubber layer is 0.8～4.0Mm,
Tires with a rubber layer that is not long enough to reach the bead . The tire according to claim 1, wherein the rubber component of the rubber layer is styrene butadiene rubber. The tire according to claim 1 or 2, wherein the width of the rubber layer is 0.5 to 2.0 times the width of the breaker.

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