JP3391703B2 - Pneumatic tire - Google Patents

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 The sidewall rubber of a pneumatic tire contains a compounding agent such as oil, wax and an anti-aging agent in order to reinforce the sidewall rubber. However, the sidewall rubber also has a beautiful black color when it is new, but the compounding agents described above migrate to the outer surface of the rubber with the passage of time, and the sidewall rubber does not discolor such as white discoloration, brown discoloration or blue discoloration. However, there was a problem that the appearance was significantly impaired.

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

Further, for example, a fine pattern such as graining or knurling is formed on the outer surface of the sidewall rubber by using a vulcanizing mold to make the deterioration of the appearance inconspicuous as much as possible. Since this method also does not prevent discoloration of the side wall rubber, its effect is small.

The inventors of the present invention have conducted extensive studies in view of the above situation, and as a result, based on the fact that a rubber composition in which mica particles having a silane coupling agent preliminarily adhered thereto are mixed is used as a sidewall rubber, is basically used. The inventors have found that the discoloration of the sidewall rubber as described above can be effectively hidden by the reflection of light from the mica particles without impairing the original durability required for the sidewall rubber itself, and have completed the present invention. It was

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

As described above, an object of the present invention is to provide a pneumatic tire capable of maintaining the outer appearance of the sidewall rubber in a good condition for a long period of time without impairing its durability.

[0008]

The invention according to claim 1 of the present invention is a pneumatic tire comprising a carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion, wherein the sidewall portion is provided. The side wall rubber disposed in is a rubber base material 1 made of natural rubber, butadiene rubber, or a compounded rubber of natural rubber and butadiene rubber.
00 parts by weight is flaky and has an average surface area of 1 on one side.
3 to 30 parts by weight of a composite mica particle in which a silane coupling agent is previously attached 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 particles are oriented so as to be exposed on the outer surface of the sidewall part. Is characterized by.

According to the invention of claim 2, the silane coupling agent is bis- (3-triethoxysilylpropyl) tetrasulfide, γ-glycidoxypropyl-trimethoxysilane, γ-mercaptopropyl-trimethoxy. The pneumatic tire according to claim 1, comprising silane, γ-methacryloxypropyl-trimethoxysilane or γ-aminopropyl-triethoxysilane.

The invention according to claim 3 is characterized in that the composite mica particles are formed by immersing the mica particles in the silane coupling agent.
Or the pneumatic tire according to 2.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION 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 and locked around a bead core 5 of a bead portion 4 from a tread portion 2 through a sidewall portion 3 and an inner side of the tread portion 2. 1 illustrates a radial tire for a passenger vehicle including a belt layer 7 arranged on the outer side in the tire radial direction of the carcass 6, the left half being substantially symmetrical with the right half.

The carcass 6 is composed of, for example, one or more, in this example, one ply of a radial structure in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire equator C. As the carcass cord, an organic fiber cord such as nylon, rayon or polyester is adopted in this example, but a steel cord may also be adopted according to the type of tire if necessary.

The belt layer 7 has 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, in this example, two inner and outer belt plies 7A,
7B is formed by stacking the cords in a direction in which the cords cross each other. In addition, the belt ply 7A in the radial direction
Is formed wider than the outer belt ply 7B. As the belt cord, a steel cord is used in this example, but a highly elastic organic fiber cord such as aramid or rayon can also be used if necessary.

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

As described above, by mixing the composite mica small piece 10 with the sidewall rubber 9 and orienting it so as to be exposed on the outer surface of the sidewall portion 3, the sidewall rubber 9 made of black rubber will change with time. Even if discoloration occurs, the outer surface of the sidewall rubber always exhibits a glitter due to the reflection of light by the composite mica small 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.

Further, the mica small piece 11 is used as a composite mica small piece 10 to which a silane coupling agent is attached prior to compounding with the rubber base material. Thereby, the coupling agent acts as a connecting bridge between the mica small piece 10 and the rubber base material, the adhesiveness with the rubber base material is further enhanced, and the deterioration of the durability of the sidewall rubber 9 is also effectively prevented. sell.

In this example, the side wall rubber 9 is arranged outside the carcass 6 in the tire axial direction to form the outer surface of the tire. However, the side wall rubber 9 may be composed of two or more layers. You can. At this time, the rubber layer containing the mica particles is arranged on the outermost side in the tire axial direction. Further, as the rubber base material of the sidewall rubber 9, natural rubber, butadiene rubber, or a blend rubber in which natural rubber and butadiene rubber are blended, which are excellent in adhesiveness, scratch resistance and flexibility, can be preferably adopted.

Mica is a mineral that has the property of peeling off evenly and thinly, and various types such as muscovite, phlogopite and biotite can be adopted. In this example, muscovite (trade name: Muscovite , Main component KAl ₂ ·
Although AlSi ₃ O ₁₀ (OH) ₂ ) is adopted, these may be used alone or in combination of two or more.

Further, it is desired that the average surface area of one surface of the mica small piece 11 is 1 × 10 ⁻⁴ to 4 (mm ² ) in consideration of variations. 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 extrusion molding of the sidewall rubber 9, and the effect of reflecting light will be reduced.
On the other hand, 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 deteriorated. Preferably, the average surface area of the mica particles 11 is 1 × 10 ⁻² to 4 (mm ² ).

Further, the mica small piece 11 needs to be previously treated by a means such as spraying or dipping so that the silane coupling agent adheres to the surface thereof. Without such coupling agent adhesion treatment, the adhesiveness between the rubber base material and the mica particles is reduced, and the sidewall rubber 9
Durability will be significantly reduced.

Examples of such silane coupling agents include bis- (3-triethoxysilylpropyl).
Those selected from tetrasulfide, γ-glycidoxypropyl-trimethoxysilane, γ-mercaptopropyl-trimethoxysilane, γ-methacryloxypropyl-trimethoxysilane or γ-aminopropyltriethoxysilane are preferable. Further, the silane coupling agent is preferably added in a proportion of 1 to 10% by weight in the total mass of the composite mica small piece 11.

Further, the composite mica small piece 10 to which the silane coupling agent is attached needs to be mixed in an amount of 3 to 30 parts by weight with respect to 100 parts by weight of the rubber base material. If the compounding amount of the composite mica particles is less than 3 parts by weight, the light reflection amount is small, and if it exceeds 30 parts by weight, the durability of the sidewall rubber 9 tends to be deteriorated. Preferably, the compounding amount of the composite mica small piece 10 is 10 to 30 parts by weight, more preferably 20 to 10 parts by weight based on 100 parts by weight of the rubber base material.
30 parts by weight is desirable.

Further, the sidewall rubber 9 is required to contain at least 20 to 70 parts by weight of carbon and 5 to 30 parts by weight of oil in accordance with the customary practice. In particular, a sidewall rubber composition having a beautiful black color and suitably reinforced with carbon can be obtained. Needless to say, 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 compounds. The side wall rubber 9 containing such a mica small piece may be provided on at least one side wall portion 3.

[0024]

EXAMPLES A pneumatic tire having a tire size of 185 / 60R14 and a sidewall rubber containing the mica small pieces shown in Table 1 was experimentally produced (Examples 1 and 2,
Comparative Examples 1 to 5 and Conventional Example), the appearance of the side wall portion was compared between when new and after running, and the durability was also tested.

The outer appearance of the sidewall was evaluated by an index of 100 for each new tire of the conventional example (without mica small pieces) and after running. For durability, a drum tester was used. The maximum load is 1.3 times the standard maximum load to bend it significantly and speed is 2000km at 40km.
After running for m, the side wall rubber was damaged by the conventional example 1
It evaluated by the index set to 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 tires of the examples had a glittering side wall portion and maintained a very beautiful appearance and durability even after running. On the other hand, Comparative Example 1 in which the size and amount of the mica pieces are different
In No. 4, it was not possible to achieve both of these effects.

[0029]

As described above, in the present invention, the side wall rubber is blended with the composite mica particles obtained by adhering the silane coupling agent to the mica particles, and the orientation is performed so that the composite mica particles are exposed on the outer surface of the sidewall portion. As a result, even if the black rubber sidewall rubber discolors over time, the outer surface of the sidewall rubber always exhibits a sparkle due to the reflection of light by the small particles of the composite mica, which effectively causes the discoloration. Can be hidden. Therefore, the appearance of the sidewall portion can be improved for a long period of time.

The mica flakes are used as composite mica flakes to which a silane coupling agent is attached prior to compounding with the rubber base material, whereby the adhesiveness with the rubber base material is further enhanced, and the side wall rubber is It is also possible to effectively prevent a decrease in durability.

[Brief description of drawings]

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

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

[Explanation of symbols]

2 tread section 3 Side wall part 4 bead section 5 bead core 6 carcass 6A carcass ply 7 Belt layer 9 Sidewall rubber 10 Composite mica pieces

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI C08L 9/00 C08L 9/00 (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 1/00 B60C 13/00 C08K 3/04 C08K 9/06 C08L 7/00 C08L 9/00

Claims (3)

(57) [Claims] 1. A pneumatic tire having a carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion, wherein the sidewall rubber disposed in the sidewall portion is natural rubber, butadiene rubber, or 100 parts by weight of a rubber base material composed of a compounded rubber of natural rubber and butadiene rubber is in the form of flakes and the average surface area of one side is 1 × 10 ⁻⁴ to
3 to 30 parts by weight of composite mica particles in which a silane coupling agent is previously attached to 4 (mm ² ) mica particles and 20 to 70
A black rubber composition containing at least 5 parts by weight of carbon and 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 part. Pneumatic tires. 2. The silane coupling agent is bis- (3
-Triethoxysilylpropyl) tetrasulfide,
γ-glycidoxypropyl-trimethoxysilane, γ
A pneumatic tire according to claim 1, which comprises -mercaptopropyl-trimethoxysilane, γ-methacryloxypropyl-trimethoxysilane or γ-aminopropyl-triethoxysilane. 3. The pneumatic tire according to claim 1, wherein the composite mica flakes are formed by immersing the mica flakes in the silane coupling agent.