JP2013075934A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire excellent in the quiet performance, fracture characteristics, and high-speed durability performance.SOLUTION: The pneumatic tire has a rubber layer between a breaker and an inner liner, wherein the rubber layer consists of a rubber composition including a rubber component and a complex that is obtained by mixing zinc oxide fine particles having an average primary particle diameter of 300 nm or less with fatty acid at a temperature equal to or higher than the melting point of the fatty acid.

Description

The present invention relates to a pneumatic tire.

In recent years, there has been a strong demand for low noise and quietness of passenger cars, and therefore, high-frequency quietness is also required for radial tires for passenger cars. As noise caused by tires, pattern noise based on a tread pattern, squeak / slip noise between a road surface and road noise during running are known.

Conventionally, the quiet performance of a tire has been generally improved by a tire pattern or a contact shape, but the improvement from the blending side of the rubber composition is still insufficient and there is room for improvement. As a technique for improving the silent performance by improving the blending surface, it is conceivable to increase the damping characteristics by using a blended rubber having a high loss tangent tan δ, and specifically, increasing the amount of carbon black is known.

However, when such a method is used, there is a problem that the high speed durability performance deteriorates because the rubber composition becomes high temperature during high speed running. It is conceivable to improve the high-speed durability performance by adding fine zinc oxide, but fine particles are difficult to disperse, so if the kneading is insufficient, poor dispersion will occur, and conversely the destructive properties will be It can get worse.

For example, Patent Document 1 discloses that the performance is improved by using a rubber composition containing fine particle zinc oxide and two types of silica, but the dispersibility of the fine particles is not sufficient, so the performance is improved. From this point of view, there is still room for improvement.

JP 2008-101127 A

The object of the present invention is to solve the above-mentioned problems and to provide a pneumatic tire excellent in quiet performance, fracture characteristics and high-speed durability performance.

The present invention is a pneumatic tire having a rubber layer between a breaker and an inner liner, wherein the rubber layer contains a rubber component, fine zinc oxide having an average primary particle size of 300 nm or less, and a fatty acid, not less than the melting point of the fatty acid. It is related with the pneumatic tire which consists of a rubber composition containing the complex obtained by mixing at the temperature of.

In the pneumatic tire, the rubber layer is preferably disposed between the breaker and the carcass and / or between the carcass and the inner liner.
In the complex, it is preferable that the content of the fine zinc oxide in a total of 100% by mass of the fine zinc oxide and the fatty acid is 10 to 90% by mass.

In the pneumatic tire, the rubber composition (the rubber layer) preferably includes 0.1 to 6 parts by mass of the fine particle zinc oxide with respect to 100 parts by mass of the rubber component.
The rubber composition (the rubber layer) has a carbon black content of 0 to 200 parts by mass, a silica content of 0 to 100 parts by mass, the carbon black, and 100 parts by mass of the rubber component. The total content of the silica is preferably 30 to 200 parts by mass.

According to the present invention, in a pneumatic tire having a rubber layer between a breaker and an inner liner, in the rubber layer, a rubber component, fine zinc oxide having an average primary particle size of 300 nm or less and a fatty acid are equal to or higher than the melting point of the fatty acid. Since the rubber composition containing the complex obtained by mixing at the temperature is used, excellent quiet performance, fracture characteristics and high-speed durability performance can be obtained.

It is a section explanatory view of the tire which shows one form of the insertion position of the rubber layer in the pneumatic tire of the present invention. It is a figure which shows the measurement result of FT-IR of the complex prepared by the manufacture example.

The pneumatic tire of the present invention has a rubber layer between a breaker and an inner liner, and the rubber layer contains a rubber component, fine zinc oxide having an average primary particle size of 300 nm or less, and a fatty acid at a temperature equal to or higher than the melting point of the fatty acid. And a complex obtained by mixing with a rubber composition.

It is expected to improve the fracture characteristics and improve the high-speed durability by reducing the fracture nuclei of rubber using fine particle zinc oxide. However, the fine zinc oxide is sufficiently dispersed in the usual several kneading steps. It is generally difficult to do. Therefore, when using fine particles having an average primary particle size of 300 nm or less, a high level of dispersion technique is required, and for example, a large number of kneading times are required, resulting in a decrease in productivity. On the other hand, if the kneading is insufficient, the fracture characteristics may be deteriorated due to poor dispersion.

In the present invention, a complex obtained by mixing finely divided zinc oxide and a fatty acid, which are difficult to disperse, at a temperature equal to or higher than the melting point of the fatty acid is used after being easily dispersed. That is, premixing makes a complex state of fatty acid zinc, which can be easily dispersed, so that it can be highly dispersed by kneading several times without increasing the number of times of special kneading. Therefore, it is possible to uniformly disperse the finely divided zinc oxide, improving the fracture characteristics and improving the high-speed durability while obtaining good productivity. Moreover, since the rubber layer using such a component is provided between the breaker and the inner liner, excellent quiet performance can be obtained. Therefore, in the present invention, a pneumatic tire excellent in quiet performance, fracture characteristics, and high speed durability performance can be provided.

In the pneumatic tire of the present invention, a rubber layer is disposed between the breaker and the inner liner. The position where the rubber layer is provided is not particularly limited as long as it is between the tire breaker and the inner liner. For example, the form shown in FIG. FIG. 1 is a cross-sectional explanatory view of a tire showing an embodiment of a rubber layer insertion position in the present invention. In addition, the pneumatic tire of this invention is not limited to the form of FIG.

The tire shown in FIG. 1 has a second breaker 1, a first breaker 2, a carcass 3, and an inner liner 4, and a rubber layer in the present invention is provided between the second breaker 1 and the inner liner 4. It has been. Specifically, the rubber layer C is inserted between the first breaker 2 and the carcass 3, and the rubber layer D is inserted between the carcass 3 and the inner liner 4.

When the rubber layer is disposed on the first breaker 2 (base tread A) or between the first breaker 2 and the second breaker 1 between the first breaker 2 and the second breaker 1, the high speed durability is deteriorated, and the rubber layer is disposed on the inner side E of the inner liner 4. The rubber layer deteriorates due to air oxidation. On the other hand, by arranging the rubber layer C between the first breaker 2 / carcass 3 and the rubber layer D between the carcass 3 / inner liner 4 in the present invention, noise is suppressed and silent performance is improved. it can.

The rubber layer C and / or the rubber layer D comprises a rubber composition containing a rubber component and a complex obtained by mixing fine zinc oxide having an average primary particle diameter of 300 nm or less and a fatty acid at a temperature not lower than the melting point of the fatty acid. .

Rubber components that can be used in the rubber layers C and D include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), and chloroprene rubber (CR). And diene rubbers such as butyl rubber (IIR) and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more. Among them, NR and SBR are preferable because high tan δ and excellent fracture characteristics can be obtained, and a combination of these is more preferable.

The NR is not particularly limited, and for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20, and the like can be used.

The content of NR in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 40% by mass or more, and further preferably 55% by mass or more. If it is less than 20% by mass, sufficient fracture characteristics tend not to be obtained. The content is preferably 95% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less. If it exceeds 95% by mass, tan δ tends to decrease.

The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR) and the like can be used. Among these, S-SBR is preferable because blowout hardly occurs.

The styrene content of SBR is preferably 15% by mass or more, more preferably 20% by mass or more. If it is less than 15% by mass, tan δ may not be sufficiently increased. The styrene content is preferably 40% by mass or less, more preferably 30% by mass or less. When it exceeds 40% by mass, heat is likely to be generated, and high-speed durability performance may be deteriorated.
Incidentally, styrene content ^is calculated by H 1 -NMR measurement.

The content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. If it is less than 5% by mass, tan δ tends to decrease. The content is preferably 80% by mass or less, more preferably 60% by mass or less, and still more preferably 45% by mass or less. If it exceeds 80% by mass, sufficient fracture characteristics tend not to be obtained.

In the rubber layers C and D, the complex is obtained by mixing fine zinc oxide having an average primary particle size of 300 nm or less and a fatty acid at a temperature equal to or higher than the melting point of the fatty acid, and can be used as a vulcanization aid. .

The average primary particle diameter of the particulate zinc oxide is 300 nm or less, preferably 150 nm or less, more preferably 100 nm or less, and still more preferably 50 nm or less. The lower limit of the average primary particle diameter of the fine particle zinc oxide is not particularly limited, but is preferably 20 nm or more, more preferably 40 nm or more. Within the above range, excellent fracture characteristics and high-speed durability can be obtained.
In addition, the average primary particle diameter of fine particle zinc oxide is an average particle diameter (average primary particle diameter) converted from the specific surface area measured by BET method by nitrogen adsorption.

The fatty acid is not particularly limited, and examples thereof include saturated fatty acids such as stearic acid, palmitic acid, myristic acid, and lauric acid, and unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. Of these, saturated fatty acids are preferable because of their excellent fracture characteristics and high-speed durability, and those represented by the following formula are more preferable.
CH ₃ (CH ₂ ) _r COOH
(In the formula, r represents an integer of 10 to 30 (preferably 14 to 18).)
As such a fatty acid, stearic acid is preferable because it has high fracture characteristics and high-speed durability performance.

The complex can be prepared by mixing fine particle zinc oxide and a fatty acid at a temperature equal to or higher than the melting point of the fatty acid, for example, 40 to 100 ° C. for 1 to 30 minutes (preferably 69.6 to 80 ° C. for 3 to 10 minutes. More preferably, the mixing may be performed under conditions of 70 to 75 ° C. for 3 to 10 minutes. The mixing step can be performed using a known heating device or mixing device. For example, fine particles of zinc oxide and fatty acid are stirred and heated using a Henschel mixer, a water bath, an oil bath, etc., and the fatty acid is melted to form fine particles. Complexes can be prepared by mixing with zinc oxide.

The obtained complex is preferably in a solid state at normal temperature (23 ° C.). By kneading the solid state complex with the rubber component, the fine zinc oxide and the fatty acid can be well dispersed in the rubber component, and the fracture characteristics and the high-speed durability performance can be improved.

In the above complex, the content of the fine zinc oxide in the total 100% by mass of the fine zinc oxide and the fatty acid is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 40% by mass or more. If it is less than 10% by mass, the effect of improving the fracture characteristics and the high-speed durability performance may not be sufficiently obtained. The content of fine zinc oxide is preferably 90% by mass or less, more preferably 70% by mass or less. When it exceeds 90 mass%, there is little fatty acid and there exists a possibility that the above-mentioned improvement effect cannot fully be acquired.

In the rubber composition for forming the rubber layers C and D, the content of the fine particle zinc oxide is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 0.1 parts by mass, sufficient crosslinking efficiency cannot be obtained, and excellent fracture characteristics and high-speed durability performance may not be obtained. Moreover, this content becomes like this. Preferably it is 6 mass parts or less, More preferably, it is 4 mass parts or less. When the amount exceeds 6 parts by mass, the fine zinc oxide is not dispersed and becomes a fracture nucleus, and the fracture characteristics tend to deteriorate.

In the rubber composition forming the rubber layers C and D, the content of the fatty acid is preferably 0.1 parts by mass or more, and more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 0.1 parts by mass, the crosslinking density is low and the fracture characteristics tend to deteriorate. Moreover, this content becomes like this. Preferably it is 6 mass parts or less, More preferably, it is 4 mass parts or less. If it exceeds 6 parts by mass, the workability tends to deteriorate.

In addition, fine particle zinc oxide and fatty acid may be added separately in addition to the above complex, and in this case, each of the above contents means the total amount contained in each rubber composition forming the rubber layers C and D. .

The rubber composition for forming the rubber layers C and D preferably contains carbon black. Due to this reinforcing effect, excellent fracture characteristics and high-speed durability performance can be obtained.

Examples of carbon black that can be used include GPF, FEF, HAF, ISAF, and SAF, but are not particularly limited. Carbon black may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 15 m ² / g or more, and more preferably 20 m ² / g or more. If it is less than 15 m ² / g, tan δ may not be sufficiently increased. Further, the nitrogen adsorption specific surface area of the carbon black is preferably from ^{60 m} 2 / g, more preferably not more than ^{40m 2 / g, 35m 2 /} g or less is more preferable. If it exceeds 60 m ² / g, the temperature becomes high during high-speed running, and the high-speed durability performance may deteriorate.
In addition, the nitrogen adsorption specific surface area of carbon black is measured based on JISK6217-2: 2001.

Carbon black has a dibutyl phthalate (DBP) oil absorption of preferably 20 ml / 100 g or more, more preferably 50 ml / 100 g or more, and even more preferably 70 ml / 100 g or more. If it is less than 20 ml / 100 g, the fracture characteristics may deteriorate. The DBP oil absorption of carbon black is preferably 105 ml / 100 g or less, more preferably 95 ml / 100 g or less. If it exceeds 105 ml / 100 g, the temperature becomes high during high-speed traveling, and the high-speed durability performance may deteriorate.
The DBP oil absorption of carbon black is measured according to JIS K6217-4: 2001.

In the rubber composition forming the rubber layers C and D, when carbon black is included, the carbon black content is preferably 60 parts by mass or more, more preferably 80 parts by mass or more, with respect to 100 parts by mass of the rubber component. More preferably, it is 90 mass parts or more. If it is less than 60 parts by mass, sufficient tan δ and fracture characteristics may not be obtained. The carbon black content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and still more preferably 120 parts by mass or less. If it exceeds 200 parts by mass, the fracture characteristics and high-speed durability performance may be reduced.

Further, the rubber composition forming the rubber layers C and D may contain silica. When silica is contained, the content thereof is preferably 10 to 100 parts by mass, more preferably 20 to 80 parts by mass with respect to 100 parts by mass of the rubber component. Furthermore, when carbon black and / or silica are included, the total content thereof is preferably 30 to 200 parts by mass, more preferably 50 to 160 parts by mass with respect to 100 parts by mass of the rubber component. By adjusting to the above range, the effect of the present invention can be obtained satisfactorily. In addition, when mix | blending a silica, it is desirable to add a silane coupling agent further.

The rubber composition forming the rubber layers C and D preferably contains oil. Thereby, tan δ is increased and good silent performance is obtained. As the oil, for example, process oil, vegetable oil, or a mixture thereof can be used.

As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. Vegetable oils include castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Of these, an aroma-based process oil is preferably used.

In the rubber composition forming the rubber layers C and D, the oil content is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, with respect to 100 parts by mass of the rubber component. If it is less than 10 parts by mass, tan δ may not be sufficiently increased. The oil content is preferably 150 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 60 parts by mass or less. When it exceeds 150 mass parts, there exists a possibility that a fracture characteristic may deteriorate.

In addition to the components described above, the rubber composition contains compounding agents generally used in the production of rubber compositions, such as stearic acid, various anti-aging agents, anti-ozone degradation agents, waxes, vulcanizing agents, and vulcanization accelerators. An agent or the like can be appropriately blended.

The pneumatic tire of the present invention shown in FIG. 1 and the like has a rubber layer between the breaker and the inner liner (rubber layer C between the first breaker 2 and the carcass 3, and rubber between the carcass 3 and the inner liner 4). The layer D and the like can be applied and manufactured by a usual method. That is, the rubber composition prepared by a known kneading method by blending the above components is extruded in accordance with the shapes of the rubber layers C and D at an unvulcanized stage, and is combined with other tire members by a tire molding machine. An unvulcanized tire is formed by molding by an ordinary method. The unvulcanized tire is heated and pressurized in a vulcanizer to produce a tire.

The pneumatic tire of the present invention is suitably used for passenger car tires, particularly passenger car radial tires.

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.
NR: TSR20
SBR: SBR1502 (styrene content: 23.5% by mass) manufactured by Sumitomo Chemical Co., Ltd.
Carbon Black: Show Black N660 manufactured by Cabot Japan Co., Ltd. (N ₂ SA: 28 m ² / g, DBP oil absorption: 90 ml / 100 g)
Aroma oil: Process X140 made by Japan Energy Co., Ltd.
Zinc oxide: Three types of zinc oxide (average primary particle size: 1.0 μm) manufactured by Hakusui Tech Co., Ltd.
Fine zinc oxide 1: Zincock Super F-1 manufactured by Hakusuitec Co., Ltd. (average primary particle size: 100 nm)
Fine zinc oxide 2: Zinccock Super F-3 (average primary particle size: 50 nm) manufactured by Hakusui Tech Co., Ltd.
Fine Zinc Oxide 1, 2 and Zinc Oxide Complex: The following production examples: Stearic acid: Sulfur stearate manufactured by NOF Corporation: Powdered sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Ouchi Shinsei Chemical Industry Co., Ltd. Noxeller NS (Nt-butyl-2-benzothiazylsulfenamide)

(Production Example Preparation of Complex)
In accordance with the formulation shown in Table 1, using a Henschel mixer, stearic acid was heated to a melting temperature (69 to 72 ° C.) or higher, and after confirming that the stearic acid had melted, various zinc oxides were added. After stirring and mixing for 5 minutes, the complex was obtained by air cooling at room temperature.

(Confirmation of complex: FT-IR)
Regarding the complex of fine zinc oxide and stearic acid prepared in Production Example, and the complex of zinc oxide and stearic acid, the formation of the complex was confirmed using FT-IR. The formation of the complex was confirmed using fine zinc oxide. (FIG. 2).

(Examples and Comparative Examples)
According to the blending contents shown in Table 1, materials other than sulfur and vulcanization accelerator were kneaded for 3 minutes at 150 ° C. using a BP Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes under a condition of 80 ° C. using a biaxial open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 12 minutes to obtain a vulcanized rubber composition.

Further, the obtained unvulcanized rubber composition is formed into the shapes of rubber layers C and D in FIG. 1, and is bonded to other tire members to form a tire, followed by press vulcanization at 170 ° C. for 15 minutes. A test tire (tire size: 195 / 65R15) was manufactured.

The following evaluation was performed using the obtained vulcanized rubber composition and test tire. Each test result is shown in Table 1.

(Destructive properties)
The vulcanized rubber composition was subjected to a tensile test using a No. 3 dumbbell according to JIS K 6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”, and the breaking strength (TB) and elongation at break were measured. (EB) was measured. Based on the obtained measured value, a value of (TB × EB) / 2 was calculated, and Comparative Example 1 was set to 100, and the value of each formulation was displayed as an index. The larger the value, the better the rubber strength.

(High-speed durability)
Using a drum tester, the internal pressure (260 kPa), rim (6.0 JJ), longitudinal load (5.26 kPa), and camber angle (4 °) are satisfied in accordance with the load / speed performance test specified by ECE30. The step speed method was used. In the test, the running speed was sequentially increased and the speed (km / H) when the tire broke was measured. The breaking speed of Comparative Example 1 was set to 100, and each tire was displayed as an index. The larger the value, the better the high-speed durability performance.

(Viscoelasticity test)
With respect to the vulcanized rubber composition, the loss tangent tan δ at 60 ° C. was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. under conditions of an initial strain of 10%, a dynamic strain of 2%, and a vibration frequency of 10 Hz. The tan δ of Comparative Example 1 was set to 100, and each formulation was displayed as an index. The larger the value, the higher the damping characteristics and the better the quiet performance.

(Road noise performance)
A test tire is attached to all wheels of an automobile under conditions of internal pressure (internal pressure specified in JIS), and a smooth road surface is run at a speed of 80 km / h, and the overall noise level dB ( A) was measured and displayed as an index with Comparative Example 1 taken as 100. The larger the index, the lower the road noise.

In the example using the complex of fine zinc oxide and stearic acid, the fracture characteristics and the high-speed durability were improved as compared with the comparative example in which the fine zinc oxide and stearic acid were simply kneaded. In particular, in Comparative Example 3 in which fine zinc oxide having an average primary particle size of 50 nm was simply mixed, the dispersibility was poor and the performance was worse than in Comparative Example 1 using ordinary zinc oxide, but in complexed Example 2, The performance was significantly improved. Moreover, the quiet performance of the tire was also excellent. Moreover, in the normal mixture of zinc oxide, no complex was formed, and the performance was not sufficiently improved (Comparative Example 4, FIG. 2).
In addition, even when other fatty acids such as palmitic acid, myristic acid, lauric acid, oleic acid, linoleic acid, linolenic acid and fine zinc oxides 1 and 2 were used, the complex was formed well and the performance was improved. .

DESCRIPTION OF SYMBOLS 1 Second breaker 2 First breaker 3 Carcass 4 Inner liner A Base tread B Rubber layer C inserted between the first breaker 2 and the second breaker 1 Inserted between the first breaker 2 and the carcass 3 Rubber layer D Rubber layer inserted between the carcass 3 and the inner liner 4 E Rubber layer disposed inside the inner liner 4

Claims (5)

A pneumatic tire having a rubber layer between a breaker and an inner liner,
The pneumatic tire which consists of a rubber composition in which the said rubber layer contains a rubber component and the complex obtained by mixing the fine particle zinc oxide and fatty acid with an average primary particle diameter of 300 nm or less at the temperature more than melting | fusing point of the said fatty acid. The pneumatic tire according to claim 1, wherein the rubber layer is disposed between the breaker and the carcass and / or between the carcass and the inner liner. The pneumatic tire according to claim 1 or 2, wherein, in the complex, a content of the fine zinc oxide in a total of 100% by mass of the fine zinc oxide and the fatty acid is 10 to 90% by mass. The pneumatic tire according to any one of claims 1 to 3, wherein the rubber composition includes 0.1 to 6 parts by mass of the particulate zinc oxide with respect to 100 parts by mass of the rubber component. The rubber composition has a carbon black content of 0 to 200 parts by weight, a silica content of 0 to 100 parts by weight, and a total content of the carbon black and the silica with respect to 100 parts by weight of the rubber component. It is 30-200 mass parts, The pneumatic tire in any one of Claims 1-4.

Images