JPH11348513A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a good appearance of side wall rubber of a tire for a prolonged period. SOLUTION: Side wall rubber 9 allocated at a side wall part 3 comprises a 100 pts.wt. of rubber base material 1 made of natural rubber, butadiene rubber, or compounded rubber composed of natural rubber and butadiene rubber, and a black rubber composition containing at least 3-30 pts.wt. of composite mica chips 10 formed with mica flakes with an average area of 1×10<-4> -4 (mm<2> ) on each side with silane coupling agent adhered in advance, 20-70 pts.wt. of carbon and 5-30 pts.wt. of oil. The composite mica chips are arranged to be exposed on the external surface of the side wall 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of improving the appearance of sidewall rubber over a long period of time.

[0002]

2. Description of the Related Art In order to reinforce sidewall rubber of a pneumatic tire, a compounding agent such as oil, wax, an antioxidant and the like is contained. However, when new, the sidewall rubber also has a beautiful black color, but the above-mentioned compound migrates to the outer surface of the rubber with the passage of time, and the sidewall rubber does not change its color to white, brown or blue. However, there is a problem that the external appearance is significantly impaired.

Conventionally, various improvements have been made to the above-mentioned compounding agents in order to prevent such deterioration of the appearance of the side wall portion, but the effect has not yet been sufficiently exhibited. .

[0004] In addition, for example, by devising a fine pattern such as a graining process or a knurling process on the outer surface of the side wall rubber by a vulcanizing mold, it has been devised to make the deterioration of the appearance as small as possible. This method also does not prevent the discoloration of the sidewall rubber itself, so that its effect is small.

The inventors of the present invention have conducted intensive studies in view of the above situation, and have found that a rubber composition obtained by mixing mica particles having a silane coupling agent previously attached to a side wall rubber is basically used. The present inventors have found that the discoloration of the sidewall rubber as described above can be effectively hidden by the reflection of the light of the mica pieces without impairing the original durability required for the sidewall rubber itself, and completed the present invention. Was.

As a technique for blending mica with sidewall rubber, for example, Japanese Patent Application Laid-Open No. Sho 59-118509 has already been proposed. In this proposal, the sidewall rubber layer itself is transparent or translucent. Since it is made of a mixture and belongs to a technical field significantly different from ordinary black rubber tires, it does not provide a motivation to prevent deterioration of appearance due to discoloration of the sidewall portion.

[0007] As described above, an object of the present invention is to provide a pneumatic tire capable of maintaining the appearance of a sidewall rubber in a good state for a long period without impairing durability.

[0008]

According to the present invention, there is provided a pneumatic tire having a carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion. Is a rubber base material 1 made of natural rubber, butadiene rubber, or a blended rubber of natural rubber and butadiene rubber.
Flakes and an average surface area per side of 1
3 to 30 parts by weight of a composite mica particle in which a silane coupling agent is previously adhered to a mica particle of × 10 ^-4 to 4 (mm ² );
It is made of a black rubber composition containing at least 20 to 70 parts by weight of carbon and 5 to 30 parts by weight of oil, and the composite mica pieces are oriented so as to be exposed on the outer surface of the sidewall portion. It is characterized by.

In a preferred embodiment of the present invention, the silane coupling agent is bis- (3-triethoxysilylpropyl) tetrasulfide, γ-glycidoxypropyl-trimethoxysilane, γ-mercaptopropyl-trimethoxysilane. The pneumatic tire according to claim 1, comprising silane, γ-methacryloxypropyl-trimethoxysilane, or γ-aminopropyl-triethoxysilane.

According to a third aspect of the present invention, the composite mica piece is formed by immersing the mica piece in the silane coupling agent.
Or the pneumatic tire according to 2.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the pneumatic tire according to the present embodiment includes a carcass 6 that is folded back around a bead core 5 of a bead portion 4 from a tread portion 2 through a sidewall portion 3 and locked, and the inside of the tread portion 2 and Fig. 3 illustrates a radial tire for a passenger car having a belt layer 7 disposed radially outside the carcass 6 in the tire radial direction, and the left half is substantially symmetric with the right half.

The carcass 6 comprises, for example, one or more plies having a radial structure in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire equator C, in this embodiment, one plies. As the carcass cord, an organic fiber cord such as nylon, rayon, or polyester is used in the present embodiment, but a steel cord may be used if necessary and further depending on the type of tire.

The belt layer 7 includes at least two belt plies 7A in which cords are arranged at a small angle of 10 to 45 ° with respect to the tire equator, and in this example, two inner and outer belt plies 7A,
7B is formed by overlapping the cords in directions that cross each other. The belt ply 7A in the radial direction
Are formed wider than the outer belt ply 7B. Although the belt cord employs a steel cord in the present embodiment, a highly elastic organic fiber cord such as aramid or rayon may be used if necessary.

In the present embodiment, the side wall rubber 9 disposed on the side wall portion 3 is applied to 100 parts by weight of the rubber base material.
As shown in FIG. 2, the mica particles 11 each having a flaky shape having a smooth surface 11a and having an average surface area of 1 × 10 ⁻⁴ to 4 (mm ² ) on one surface are preliminarily attached to a silane coupling agent.
It is composed of a black rubber composition containing at least 30 parts by weight of the composite mica particles 10, 20 to 70 parts by weight of carbon, and at least 5 to 30 parts by weight of oil. In the present embodiment, one surface of the composite mica piece 10 is oriented substantially parallel to the outer surface while being exposed to the outer surface of the sidewall portion 3 by, for example, an extrusion molding process or a calendering process of raw sidewall rubber. FIG.

As described above, the compound mica small piece 10 is blended with the side wall rubber 9 and is oriented so as to be exposed on the outer surface of the side wall portion 3. Even if the discoloration occurs, the outer surface of the sidewall rubber always shows a brilliant shine due to the reflection of light by the composite mica piece 10, and the discoloration can be effectively hidden. Therefore, the appearance of the sidewall portion 3 can be improved over a long period of time.

The mica particle 11 is used as a composite mica particle 10 to which a silane coupling agent is adhered prior to compounding with a rubber base material. As a result, the coupling agent acts as a bonding bridge between the mica particles 10 and the rubber base material, whereby the adhesion to the rubber base material is further enhanced, and the durability of the sidewall rubber 9 is effectively prevented from being reduced. sell.

In the present embodiment, the sidewall rubber 9 is arranged outside the carcass 6 in the tire axial direction and forms the outer surface of the tire. However, the sidewall rubber 9 may be composed of two or more layers. Can. At this time, the rubber layer containing the mica pieces is disposed on the outermost side in the tire axial direction. Further, as the rubber base material of the side wall rubber 9, a natural rubber, a butadiene rubber, or a blend rubber in which a natural rubber and a butadiene rubber are blended, which are excellent in adhesiveness, trauma resistance and flexibility, can be preferably used.

Mica is a mineral having the property of being able to be peeled evenly and thinly. For example, various minerals such as muscovite, phlogopite and biotite can be employed. In this example, muscovite (trade name: Muscovite) is used. , The main component KAl ₂
Although AlSi ₃ O ₁₀ (OH) ₂ ) is employed, these may be used alone or in combination of two or more.

It is desirable that the average surface area of one side of the mica small piece 11 is 1 × 10 ⁻⁴ to 4 (mm ² ) in consideration of variation. The average surface area is 1 × 10 ⁻⁴ (mm
^If it is smaller than ² ), the mica will not be oriented substantially parallel to the outer surface of the sidewall rubber 9 during the extrusion molding of the sidewall rubber 9, so that the effect of reflecting light decreases,
Conversely, if it is larger than 4 (mm ² ), the shape of the mica itself tends to be large and the durability of the sidewall rubber 9 tends to be reduced. Preferably, the average surface area of the mica piece 11 is 1 × 10 ⁻² to 4 (mm ² ).

Further, the mica particles 11 need to be subjected to a treatment such that a silane coupling agent adheres to the surface thereof by means of spraying or dipping in advance. If such a coupling agent adhesion treatment is not performed, the adhesiveness between the rubber base material and the mica particles is reduced, and the side wall rubber 9
Endurance is greatly reduced.

As such a silane coupling agent, for example, bis- (3-triethoxysilylpropyl)
Those selected from tetrasulfide, γ-glycidoxypropyl-trimethoxysilane, γ-mercaptopropyl-trimethoxysilane, γ-methacryloxypropyl-trimethoxysilane and γ-aminopropyltriethoxysilane are preferred. Further, the silane coupling agent is preferably added so as to have a ratio of 1 to 10% by weight based on the total mass of the composite mica particles 11.

It is necessary to mix 3 to 30 parts by weight of the composite mica particle 10 with the silane coupling agent adhered to 100 parts by weight of the rubber base material. When the compounding amount of the composite mica particles is less than 3 parts by weight, the amount of reflected light is small, and when it exceeds 30 parts by weight, the durability of the sidewall rubber 9 tends to decrease. Preferably, the compounding amount of the composite mica particles 10 is 10 to 30 parts by weight, more preferably 20 to 30 parts by weight, based on 100 parts by weight of the rubber base material.
It is desirable to use 30 parts by weight.

Further, it is necessary that the sidewall rubber 9 contains at least 20 to 70 parts by weight of carbon and 5 to 30 parts by weight of oil according to a customary practice. Particularly, a beautiful black and suitably reinforced sidewall rubber composition is obtained with carbon. In addition, it goes without saying that such a rubber composition may contain various additives such as an antioxidant, a vulcanization accelerator, stearic acid, a wax and a resin in addition to the above-mentioned components. Note that the sidewall rubber 9 including such mica pieces may be disposed on at least one sidewall portion 3.

[0024]

EXAMPLES A pneumatic tire having a tire size of 185 / 60R14 and having sidewall rubber containing mica particles shown in Table 1 was prototyped (Examples 1 and 2;
Comparative Examples 1-5, Conventional Example), the appearance of the sidewall portion was compared with that of a new product after running, and the durability was also tested.

The appearance of the sidewall portion was evaluated by using a conventional tire (not including mica small pieces) as a new tire and an index of 100 after running. The durability was measured using a drum tester. Apply a vertical load of 1.3 times the maximum standard load and bend it greatly.
m, and the degree of damage to the sidewall rubber
The evaluation was performed using an index of 00. Table 1 shows the test results and the like. Table 2 shows the composition of the sidewall rubber.

[0026]

[Table 1]

[0027]

[Table 2]

As a result of the test, it was confirmed that the sidewalls of the example tires were brilliantly shining, and that the tire had a very beautiful appearance and durability even after running. On the other hand, Comparative Examples 1 to 4 in which the size and the amount of mica particles were varied.
In No. 4, such effects could not be achieved at the same time.

[0029]

As described above, according to the present invention, a composite mica particle obtained by adhering a silane coupling agent to a mica particle is blended with the sidewall rubber and oriented so as to be exposed on the outer surface of the sidewall portion. By doing so, even if the sidewall rubber of the black rubber discolors with the passage of time, the outer surface of the sidewall rubber always shows glitter and shine due to the reflection of light by the composite mica particles, and the discoloration is effectively reduced. Can be hidden. Therefore, the appearance of the sidewall portion can be improved over a long period of time.

The mica particles are used as composite mica particles to which a silane coupling agent is adhered prior to blending with the rubber substrate, whereby the adhesion to the rubber substrate is further enhanced, and A decrease in durability can also be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pneumatic tire showing one embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a mica piece.

[Description of Signs] 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Carcass ply 7 Belt layer 9 Sidewall rubber 10 Composite mica small piece

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 9/00 C08L 9/00

Claims (3)

[Claims] 1. A pneumatic tire having a carcass extending from a tread portion to a bead core of a bead portion via a sidewall portion, wherein the sidewall rubber disposed on the sidewall portion is natural rubber, butadiene rubber, or 100 parts by weight of a rubber substrate composed of a blended rubber of natural rubber and butadiene rubber are flaky and have an average surface area on one side of 1 × 10 ⁻⁴ to
3 to 30 parts by weight of a composite mica particle in which a silane coupling agent is previously adhered to 4 (mm ² ) mica particles;
It is made of a black rubber composition containing at least 5 parts by weight of carbon and at least 5 to 30 parts by weight of oil, and the composite mica particles are oriented so as to be exposed on the outer surface of the sidewall portion. Pneumatic tires. 2. The method according to claim 1, wherein the silane coupling agent is bis- (3
-Triethoxysilylpropyl) tetrasulfide,
γ-glycidoxypropyl-trimethoxysilane, γ
2. The pneumatic tire according to claim 1, comprising -mercaptopropyl-trimethoxysilane, [gamma] -methacryloxypropyl-trimethoxysilane or [gamma] -aminopropyl-triethoxysilane. 3. The pneumatic tire according to claim 1, wherein the composite mica particles are formed by immersing the mica particles in the silane coupling agent.