JP2003327745A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which substantially does not allow snow and ice to adhere to the surface of a tire tread on an actual frozen road surface, and thus further improves the frictional force on ice by increasing the direct contact area between the tread surface and the frozen road surface. <P>SOLUTION: The rubber composition is obtained by incorporating 3-20 pts.wt. capsuled particles containing a water-repellent substance into a rubber matrix comprising at least one rubber component selected from a natural rubber and a diene rubber. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition, particularly a rubber composition suitable for a tire tread, and more specifically, by increasing a direct contact area between a tire tread surface and a frozen road surface, a frictional force is increased. The present invention relates to a pneumatic tire using a rubber composition for a tire tread having improved tire.

[0002]

2. Description of the Related Art A method of improving friction on ice by removing a water film generated on the surface of ice by mixing rubber with a hard foreign substance, a foaming agent, hollow particles, etc. and forming microscopic unevenness on the surface is known. It has been studied a lot in the past. Further, in Japanese Unexamined Patent Publication No. 9-241427, fine particles of a silicone-based polymer that are easily deposited on the tire tread surface are compounded in rubber, and the water repellency of the deposited silicone-based polymer is utilized to make it possible to use on a frozen road surface. A technique has also been reported in which a water film existing between the tire tread surface and the road surface is removed to improve the adhesive frictional force with the road surface.

The effect of these blending techniques is generally confirmed by the frictional force between rubber and ice, but in practice, tires running on snow and ice roads often have snow or ice on the tread surface. Because of the situation, especially when entering a frozen road from a snowy road, the snow or ice adhering to it interferes with the direct contact between the tread surface and the frozen road surface, and greatly inhibits the effect of improving the frictional force on ice by the above compounding agent. Will result in

[0004]

Therefore, according to the present invention, snow or ice does not substantially adhere to the tire tread surface on an actual frozen road surface, and thus the direct contact between the tread surface and the frozen road surface occurs. An object of the present invention is to provide a rubber composition in which the frictional force on ice is further improved by increasing the area.

[0005]

According to the present invention, 3 to 20 parts by weight of capsule particles containing a water-repellent substance in a rubber matrix containing a rubber component consisting of at least one selected from natural rubber and diene rubber. There is provided a rubber composition which is compounded in parts.

Further, according to the present invention, there is provided a rubber composition in which the water repellent substance is silicone oil.

Further, according to the present invention, there is provided a pneumatic tire having at least a tire tread made of the above rubber composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, by incorporating capsule-shaped particles encapsulating a water-repellent substance into rubber, a microscopic structure that accompanies the destruction of the capsule encapsulating the water-repellent substance on the tire tread surface in contact with a frozen road surface. Improvement of frictional force on ice by formation of uneven surface, improvement of grip on frozen road surface by removal of water film, and adhesion of snow and ice due to formation of water-repellent film on tire tread surface of water-repellent substance released by its destruction It has been found that the frictional force between the tread surface and the frozen road surface can be further improved by preventing and further increasing the direct contact area by removing the water film. Further, when the water-repellent substance is mixed with rubber as it is, the presence of the water-repellent substance causes a significant deterioration in workability such as slip in a mixer, and
Since a problem such as migration of the water-repellent substance in the rubber compound also occurs, the present invention intends to solve the problem by encapsulating the compound in a capsule.

Since the rubber composition of the present invention has the above-mentioned characteristics, it is particularly useful when used for a tire tread member of a pneumatic tire. Further, as the water-repellent substance to be encapsulated in the capsule, silicone oil is particularly preferably used because it has high water-repellent performance and stable performance.

The capsule-shaped particles containing the water-repellent substance incorporated in the rubber composition of the present invention are commercially available from Matsumoto Yushi-Seiyaku Co., Ltd. under the trade name "SIL" (silicone oil-encapsulating capsule) and the like. It can be obtained by appropriately encapsulating a water-repellent substance in a known method using a thermoplastic resin material useful as a known encapsulating agent. As the capsule-shaped particles, μm
Those of the order, especially those of 10 to 50 μm are effectively used.

The water-repellent substance contained in the capsule is, for example, silicone oil, paraffin oil,
Naphthene oil, aroma oil, or those containing fluorine resin fine particles are effectively used. Of these, use of silicone oil is particularly preferable as described above.

Further, the capsule-shaped particles are composed of the rubber component 1.
3 to 20 parts by weight, preferably 5 to 100 parts by weight
Add 15 parts by weight. When the content is less than 3 parts by weight, the desired effect cannot be exhibited, and when it exceeds 20 parts by weight, the sheeting property becomes poor, which is not preferable.

As the rubber component used in the rubber composition of the present invention, any diene rubber conventionally used for tires and other general rubber members, such as natural rubber (NR), and various butadiene rubbers. (BR), various styrene-butadiene copolymer rubbers (SBR), polyisoprene rubber (IR), acrylonitrile butadiene rubber, chloroprene rubber, ethylene-propylene-diene copolymer rubber, styrene-isoprene copolymer rubber, styrene- Synthetic rubbers such as isoprene-butadiene copolymer rubber and isoprene-butadiene copolymer rubber are used alone or in a blend of two or more kinds. When the diene rubber is used as the tire tread rubber composition of the present invention, the glass transition temperature (Tg) has an average value in order to improve both low rolling resistance, abrasion resistance and low temperature performance. It is preferable to use one having a temperature of −55 ° C. or lower.

The rubber composition of the present invention may contain, as a rubber reinforcing agent, any carbon black usually added to a rubber composition or carbon black surface-treated with silica. Further, silica can be blended. The amount of carbon black used is 20 to 80 parts by weight, preferably 30 to 60 parts by weight, based on 100 parts by weight of the rubber component. If the blending amount is too small, the rubber cannot be sufficiently reinforced, and therefore, for example, abrasion resistance is deteriorated, which is not preferable, and conversely, if the blending amount is too large, the hardness becomes too high or the workability is deteriorated. Further, silica is 0 based on 100 parts by weight of the rubber component.
˜50 parts by weight. Silica does not have to be used, and when it is used, it is preferable to use it in a blending amount within a range where the balance of tan δ is improved. If it is too large, the electric conductivity will decrease, and the cohesive force will become strong. Is not preferable because the dispersion of is insufficient. The carbon black used in the present invention has a nitrogen adsorption specific surface area (N ₂ SA) of 70 m.
² / g or more, preferably 80 to ²⁰⁰ m ² / g, and dibutyl phthalate oil absorption (DBP) of 95 ml / 100 g
As described above, it is preferable to use one having a volume of 110 to 140 ml / 100 g.

The rubber composition of the present invention is further blended with usual vulcanizing or crosslinking agents, vulcanizing or crosslinking accelerators, various oils, anti-aging agents, which are generally blended for tires and other general rubbers. Agents, fillers, plasticizers, and other various additives can be compounded, and such compounding agents can be kneaded and vulcanized into a rubber composition by a general method, and vulcanized or crosslinked it can. The amounts of these additives to be added can also be the conventional amounts generally used unless the object of the present invention is violated.

[0016]

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited to these Examples.

Preparation of Samples According to the formulation shown in Table 1, a compounding agent other than sulfur, a vulcanization accelerator and a silicone oil encapsulating capsule was mixed for 5 minutes using a 1.7 liter closed Banbury mixer, and then the above Banbury was prepared. Mix sulfur, vulcanization accelerator and capsule containing silicone oil for 3 minutes in a mixer,
A rubber composition was obtained by kneading. The mixing processability of this unvulcanized rubber composition was observed. Then, this rubber composition was heated at 170 ° C. in a mold of 15 cm × 15 cm × 0.2 cm.
Then, the desired test piece (rubber sheet) was prepared by press vulcanization for 12 minutes and the μ value on ice was measured.

Test method 1) Mixing processability: The mixing processability was qualitatively judged from the dispersed state of the mixture and the sheeting property during roll work. “Good” means that the mixture is in a dispersed state (poor dispersion mass is measured by optical observation of the cut surface of the vulcanized rubber), and if there is no problem in sheeting property, “Bad” means that there is a problem in dispersed state or sheeting property. Indicates. 2) On ice μ: ice road surface prepared in a rotating drum (ice temperature -3
After spraying a certain amount of cutting ice like snow on top of the above, the torque and rubber generated when the cylindrical rubber sample was rotated at a slip ratio of 80% (drum rotation speed 20 km / h) against the ice road surface. Additional load to the sample (ground pressure 2.5
The friction coefficient was determined from kg / cm ² ). The result is shown as an index. The larger the index, the better the μ on ice.

The results of Comparative Examples 1 to 4 and Examples 1 and 2 are shown in Table 1.

[Table 1]

According to Table 1, when a predetermined amount of silicone-containing capsules is blended, both the mixing processability and the μ on ice are improved.

[0021]

As described above, according to the present invention, it is possible to prevent snow and ice from adhering to the tread surface, and to increase the direct contact area between the tread surface and the frozen surface, thereby further improving the frictional force. it can. Therefore, the rubber composition is extremely useful when used as a tire tread rubber composition.

Claims (3)

[Claims] 1. A rubber composition comprising 3 to 20 parts by weight of capsule particles containing a water-repellent substance in a rubber matrix containing a rubber component consisting of at least one selected from natural rubber and diene rubber. 2. The rubber composition according to claim 1, wherein the water-repellent substance is silicone oil. 3. A pneumatic tire comprising at least a tire tread made of the rubber composition according to claim 1.