JP5995751B2 - How to use a pneumatic tire - Google Patents

Description

The present invention relates to a pneumatic tire and an automobile traveling method for mounting the pneumatic tire.

Various performances are required for automobile tires, and in particular, excellent wet grip performance is desired from the viewpoint of safety. As a means for improving the wet grip performance of a tire, a method for increasing tan δ at 0 ° C. is conventionally known, and various techniques have been proposed.

Further, Patent Document 1 discloses a pneumatic tire in which the performance on ice is improved by adjusting the tread surface roughness and rubber hardness after running to a predetermined range using particles mainly composed of cellulose. . However, there is still room for improvement in terms of improving wet grip performance.

JP 2003-192844 A

An object of the present invention is to solve the above-mentioned problems and to provide a pneumatic tire having good wet grip performance and an automobile traveling method using the pneumatic tire.

The present invention relates to a pneumatic tire in which a tread surface roughness Rz ^tr is adjusted in accordance with a road surface roughness Rz ^ro .

It is preferable to adjust to 0.6 ≦ Rz ^tr / Rz ^ro ≦ 1.3.

Rz ^tr is preferably 7 to 10 μm.

The present invention also relates to an automobile traveling method for mounting the pneumatic tire on an automobile.

According to the present invention, since the pneumatic tire has the tread surface roughness Rz ^tr adjusted in accordance with the road surface roughness Rz ^ro , excellent wet grip performance can be obtained.

The pneumatic tire of the present invention is obtained by adjusting the tread surface roughness Rz ^tr in accordance with the road surface roughness Rz ^ro .

Wet grip performance by adjusting Rz ^tr so that the surface roughness (Rz ^ro ) of the road surface on which the vehicle is driven and the surface roughness (Rz ^tr ) of the tread surface (contact surface) are the same or approximate. Is increased. This means that when Rz ^tr is brought closer to Rz ^ro , the road surface and the tread surface mesh with each other, the frictional force of the rubber increases, and the road surface unevenness and the tread surface unevenness and catching increase, thereby significantly improving the wet grip performance. It is inferred that

In the present invention, the tread surface roughness Rz ^tr and the road surface roughness Rz ^ro are ten-point average roughness (RzJIS) measured in accordance with Annex 1 (reference) of JIS B0601: 2001.

In the present invention, the wet grip performance increases as the tread surface roughness Rz ^tr / road surface roughness Rz ^ro is closer to 1.0, preferably 0.6 ≦ Rz ^tr / Rz ^ro ≦ 1.3, more preferably 0.7 ≦ Rz ^tr / Rz ^ro ≦ 1.2, particularly preferably Rz ^tr / Rz ^ro = 1.0.

The tread surface roughness Rz ^tr is preferably 7 to 15 μm, more preferably 7 to 12 μm, and still more preferably 7 to 10 μm. If it is less than 7 μm, the tread surface is too smooth, and there is a possibility that improvement in wet grip performance may not be expected. If it exceeds 15 μm, the tread surface roughness is too large for the road surface. There is a possibility that improvement of wet grip performance cannot be expected.

The method of adjusting Rz ^{tr in} the present invention can be used without any particular restriction on the method of adjusting the surface roughness, buffing the tread surface, adding a water-soluble compound, adding a material that volatilizes at the vulcanization temperature, and inserting a needle , Etc. Of these, addition of a water-soluble compound is preferable. For example, when a tire produced by kneading a water-soluble compound having a particle size (diameter) of 7 to 10 μm is mounted on an automobile and travels on a wet road surface, the water-soluble compound comes into contact with water on the road surface and dissolves. Since the unevenness of 7 to 10 μm is formed on the surface, the wet grip performance on the road surface having the same unevenness can be remarkably improved.

The water-soluble compound (fine particles of the water-soluble compound) is not particularly limited as long as it is a compound that dissolves in water. For example, water-soluble salts such as sodium chloride, sodium sulfate, sodium nitrate; starch, polyamine, polyvinyl alcohol, polyacryl Examples thereof include water-soluble polymers such as acid, polyacrylamide, polyethylene oxide, polyvinyl pyrrolidone, and polyvinyl amide. Of these, water-soluble salts are preferable, and sodium chloride is more preferable from the viewpoint of safety. These can be used alone or in combination of two or more.

As the average particle diameter of the water-soluble compound (fine particles of the water-soluble compound), it is preferable to appropriately adopt a value according to the road surface roughness, for example, preferably 7 to 15 μm, more preferably 7 to 12 μm, 7 10 μm is more preferable. In the present specification, the average particle size can be measured by observation with a transmission electron microscope (TEM). Specifically, a photograph is taken with a transmission electron microscope. When the shape of the fine particles is spherical, the diameter of the sphere, when the needle or bar is a short diameter, when it is irregular, the average particle diameter from the center is measured. The average value of 100 particles is the average particle size.

The tread hardness of the pneumatic tire is preferably 60 or more, more preferably 65 or more, and still more preferably 68 or more. By setting the hardness to 60 or more, the frictional force of rubber due to the engagement between the tread surface and the road surface is increased, and the wet grip performance can be improved. The tread hardness is preferably 75 or less, more preferably 72 or less, from the viewpoint of improving durability against chipping. In addition, the hardness of the tread rubber in the present invention is a hardness measured with a type A durometer (measurement temperature 25 ° C.) in accordance with JIS K6253-3: 2012.

Examples of the tread include rubber compositions having the above-described characteristics. For example, a tread rubber composition containing a rubber component, a reinforcing filler, and the like can be used.

As rubber components, natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), butyl rubber (IIR) ), Halogenated butyl rubber (X-IIR), chloroprene rubber (CR), acrylonitrile (NBR), and the like. Of these, SBR is preferable in terms of wet grip performance.

The reinforcing filler is not particularly limited, but among these, carbon black and silica are preferable. Here, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 to 140 m ² / g, more preferably 90 to 120 m ² / g (based on JIS K 6217-2: 2001). Further, the content of carbon black is preferably 20 to 100 parts by mass, more preferably 35 to 65 parts by mass with respect to 100 parts by mass of the rubber component.

You may mix | blend the said water-soluble compound with the said rubber composition. In this case, the content of the water-soluble compound is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 100 parts by mass with respect to 100 parts by mass of the rubber component, from the viewpoint that excellent wet grip performance can be obtained. 2 parts by mass.

In addition to the above-mentioned components, the rubber composition includes compounding agents generally used in the production of rubber compositions, such as zinc oxide, stearic acid, anti-aging agents, softening agents such as oil, wax, sulfur, vulcanization An accelerator or the like can be appropriately blended.

The rubber composition is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll or the like and then vulcanizing.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, a rubber composition containing various additives as necessary is extruded in accordance with the shape of the tread at an unvulcanized stage, molded by a normal method on a tire molding machine, and other tires. Laminate together with the member to form an unvulcanized tire. This unvulcanized tire can be heated and pressurized in a vulcanizer to produce a pneumatic tire.

The pneumatic tire of the present invention can be used as various tires such as passenger car tires, truck / bus tires, and studless tires. Especially, since it is excellent in wet grip performance, it can be used suitably as a tire for wet road surfaces.

Furthermore, the automobile traveling method of the present invention is to attach the pneumatic tire to an automobile, and when the attached automobile is run on a road surface, the road surface and the tread surface mesh with each other, and the frictional force of rubber increases. The wet grip performance is significantly improved.

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.
SBR: 1502 made by JSR Corporation
Carbon Black: Dia Black I manufactured by Mitsubishi Chemical Corporation
Stearic acid: Zinc oxide manufactured by NOF Corporation: Zinc oxide 2 types manufactured by Mitsui Kinzoku Mining Co., Ltd. Anti-aging agent: Santoflex 13 manufactured by Flexis
Wax: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd.
Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. (200 mesh 5% oil)
Vulcanization accelerator: NOCELLER CZ from Ouchi Shinsei Chemical Co., Ltd.

(Tire manufacturing)
According to the formulation shown in Table 1, using a Banbury mixer, chemicals other than sulfur and a vulcanization accelerator were added and kneaded for 5 minutes so that the discharge temperature was about 150 ° C. Sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded at about 80 ° C. for 3 minutes using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was molded into a tread shape, bonded to another tire member, and vulcanized at 170 ° C. for 15 minutes to prepare a test tire.

The produced test tire was evaluated as follows, and the results are shown in Table 2.

<Wet grip performance>
By buffing the tread surface of the produced test tire, tires 1 to 7 having surface roughness Rz ^tr shown in Table 2 were produced. A four-level tire was produced. About the produced tires 1-7, the friction force test was done on condition of the following using the abrasion tester LAT-100 made from VMI. A frictional coefficient μ was calculated by running a distance of 300 m, averaging the friction force at that time, and dividing by the load. The larger μ, the better the wet grip performance.
Road surface: Asphalt load: 40N
Powder: 20%
Speed: 20km / h and 40km / h

<Surface roughness>
The tread surface roughness Rz ^tr and the road surface roughness Rz ^ro of the tires 1 to 7 were observed using a laser microscope VK9500 manufactured by Keyence Corporation. By moving the stage in one direction and further connecting the images, height information was obtained for an area with a width of 1.28 mm and a length of 10.1 mm. The objective lens used 10 times. The respective data scores were 432 points and 3865 points. And according to the appendix 1 (reference) of JISB0601: 2001, ten-point average roughness was measured.

<Tread hardness>
Regarding the treads of the tires 1 to 7, the hardness at 25 ° C. was measured with a type A durometer in accordance with JIS K6253-3: 2012 “vulcanized rubber and thermoplastic rubber—how to obtain hardness”.

From Table 2, it became clear that the tires 5 to 7 whose Rz ^tr / Rz ^ro is relatively close to 1.0 have a large friction coefficient and excellent wet grip performance.

Further, when a tire prepared by further adding sodium chloride to the same compounded rubber as in Table 1 was applied to a wet road surface, the wet grip performance was remarkably improved by adjusting the surface roughness in the same manner.

Claims (1)

A pneumatic tire prepared by kneading a rubber composition in which 0.1 to 10 parts by mass of a water-soluble salt having an average particle size of 7 to 15 μm is blended with 100 parts by mass of a rubber component is mounted on an automobile and wet road surface Step 1 for running,
By the running, the water-soluble salt is dissolved in contact with moisture on the road surface, and the tread surface roughness Rz ^tr 7-10 μm and the Rz ^tr And surface roughness Rz of the road surface ^ro Is 0.6 ≦ Rz ^tr / Rz ^ro A method for using a pneumatic tire, comprising the step 2 of adjusting to ≦ 1.3.