JP2002307907A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight pneumatic tire with excellent fuel consumption performance and free from having a problem in use caused by fatigue. SOLUTION: In this pneumatic tire, a bead core 1 and/or a bead apex 2 is formed of polyphenylene-ether resin, and a rubber composition adjacent to the bead core and/or bead apex (such as a rubber composition used for a carcass ply 3) contains styrene butadiene rubber at 5 wt.% or more in a rubber component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which is lightweight and has excellent fuel efficiency, and more particularly to a pneumatic tire which uses a highly rigid resin which can be bonded to a bead core and / or a bead apex by using a high rigid resin. To a pneumatic tire.

[0002]

2. Description of the Related Art In recent years, interest in preserving the global environment has been increasing, and the demand for lower fuel consumption has become increasingly severe in automobiles. As a technique for reducing fuel consumption, weight reduction of tires is effective, and various measures such as improvement of materials have been made in order to reduce weight of tires.

[0003] On the cord side, high-strength cords have been used to reduce the wire diameter and the number of components.

On the other hand, on the rubber surface, a method such as thinning a gauge using a high reinforcing material is adopted. As the high reinforcing material, a resin such as rubber or plastic with an increased amount of a filler or a crosslinking agent is used. Have been.

[0005] However, there is a limit even if the amount of the filler or the cross-linking agent is increased for high reinforcement. Attempts have been made to use resins such as plastics, but the adhesion to adjacent rubber is extremely poor and cannot be put to practical use. As a method of improving adhesiveness, there is a method of applying an adhesive or a bondable material obtained by improving rubber as an adhesive layer on an interface between a resin and rubber, but when such an adhesive layer is used, In a product such as a tire that repeatedly experiences fatigue, there is a problem that peeling occurs and the product cannot be used.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lightweight and fuel-efficient pneumatic tire by using a resin, and to separate at the interface between the resin and another rubber due to fatigue. An object of the present invention is to provide a pneumatic tire that does not cause the problem described above.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a high rigidity is required especially in a tire part, and a rubber-adherable and lightweight high-rigidity resin is used in a bead portion where a hard rubber is used. Another object of the present invention is to reduce the weight of a pneumatic tire without causing a problem such as separation at an interface between a resin and rubber.

That is, the present invention provides a bead core and / or
Alternatively, the bead apex is made of a polyphenylene ether resin represented by the following structural formula, and the rubber composition adjacent to the bead core and / or the bead apex contains 5% by weight of a styrene-butadiene rubber in a rubber component.
The present invention relates to a pneumatic tire containing the above.

The styrene-butadiene rubber (SBR)
Is preferably 15% by weight or more.

[0010]

Embedded image

(Wherein, n represents the degree of polymerization)

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, generally, a bead portion of a pneumatic tire is located inside a sidewall portion 6 and has a triangular cross section extending from the bead core 1 and the bead core outward in the tire radial direction. Bead apex 2 of shape, carcass ply 3 folded around the bead core from the inside of the tire to the outside so as to wrap the bead apex, chafer 4 arranged along the outside of the carcass, along the inside of the carcass It has an inner liner 5 to be arranged. Further, a clinch apex 7 is arranged outside the chafer 4.

In the present invention, the bead core 1 and / or
Alternatively, the bead apex 2 comprises a polyphenylene ether resin represented by the following structural formula.

[0014]

Embedded image

(Wherein, n represents the degree of polymerization)

Since the polyphenylene ether resin has a smaller specific gravity and a higher strength than a rubber material conventionally used for a bead portion, the weight of the tire can be reduced by using the polyphenylene ether resin for the bead portion. As a result, fuel efficiency can be improved.

Resins (for example, novolak-modified phenolic resins, epoxy resins, phenol / terpene resins, etc.) which have been conventionally used for the purpose of reducing the weight of tires have no adhesiveness to rubber, and the tire molding process before,
It had to be hot-pressed with rubber or applied an adhesive layer to the interface with rubber. However, since polyphenylene ether resin has excellent adhesive strength to rubber, it can be molded at a temperature higher than the melting temperature of the resin, and then can be attached to other rubber members in the tire molding process, and in the next vulcanization process, it will be sufficiently adhered. Vulcanized. Therefore, the problem that separation occurs at the interface between the resin and the rubber due to fatigue hardly occurs.

The value of the polymerization degree n of the polyphenylene ether resin is not particularly limited, but is preferably 10,000 or more. If n is less than 10,000, the resin strength tends to be low.

In order to further increase the adhesive strength between the bead core and / or bead apex made of the polyphenylene ether resin and the adjacent rubber composition, the adjacent rubber composition contains SBR in the rubber component. I do. Since SBR has a styrene unit, it has good compatibility with the polyphenylene ether resin, is sufficiently compatible with the polyphenylene ether resin at the interface at the vulcanization temperature, and can form a strong adhesive layer by crosslinking.

Here, the adjacent rubber composition is, for example, a rubber composition used for a carcass ply when both the bead core and the bead apex are made of a polyphenylene ether resin. When only the bead core is made of a polyphenylene ether resin, for example, it is a rubber composition used for a carcass ply and a bead apex. When only the bead core is made of a polyphenylene ether resin, for example, it is a rubber composition used for a carcass ply and a bead core.

The content of SBR is 5% by weight in the rubber component.
As described above, the content is preferably 10 to 80% by weight, and more preferably 15 to 70% by weight. If the SBR content is less than 5% by weight, poor adhesion to the bead core and / or bead apex made of the phenylene resin occurs, and
If it exceeds 0% by weight, the heat buildup of the rubber composition tends to increase.

The styrene unit content of the SBR is at least 15% by weight, especially 15 to 50% by weight, and more preferably 20 to 4% by weight.
Preferably it is 5% by weight. If the styrene unit content is less than 15% by weight, poor adhesion to the bead core and / or bead apex made of the phenylene resin tends to occur, and if it exceeds 50% by weight, the heat build-up of the rubber composition tends to increase. is there.

The rubber composition may contain other rubber components such as natural rubber (NR), butadiene rubber, styrene-butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, isoprene-butadiene rubber, and styrene-isoprene rubber. Rubber, styrene-isoprene-butadiene rubber, and the like.

The rubber composition may contain other components such as carbon black, a softener, an antioxidant, stearic acid, zinc oxide, a vulcanizing agent, a vulcanization accelerator, and a vulcanization accelerator. The compounding agents used in the rubber industry can be appropriately compounded.

As carbon black, ISAF, H
AF, FEF and GPF grades are preferably used. Carbon black is 30 parts by weight based on 100 parts by weight of the rubber component.
-100 parts by weight can be blended. If the amount of carbon black is less than 30 parts by weight, the durability tends to decrease, and if it exceeds 100 parts by weight, the heat generation tends to increase.

The bead core and / or bead apex and the rubber composition are molded in the form of each member, and then bonded together with other members in a tire molding process.
Adhesive vulcanization is performed in the tire vulcanization process.

The bead core and / or bead apex may be at or above the melting temperature of the polyphenylene ether resin, for example, 250 to 350 ° C., especially 270 to 34.
Molded at 0 ° C. If the molding temperature is lower than 250 ° C., the viscosity is high, and the flow tends to be poor at the time of injection molding.
When the temperature exceeds 0 ° C., the resin is thermally decomposed, so that the resin strength tends to decrease.

The vulcanization temperature in the tire vulcanization step is 200
° C or lower, and further, 190 to 150 ° C. If the vulcanization temperature is lower than 150 ° C., the temperature near the bead portion is low, so that the flowability of the rubber around the resin is poor and the interfacial adhesive strength tends to be low. It is prone to reversion and thermal degradation.

The pneumatic tire thus obtained can be suitably used especially as a tire for passenger cars.

[0030]

EXAMPLES Examples 1 and 2 and Comparative Examples 1 and 2 (Preparation of Bead Core and Bead Apex) Using the materials shown in Table 1, bead cores and bead apex were prepared. The bead cores of Example 1 and Comparative Example 2 and the bead apex of Examples 1 and 2 and Comparative Example 2 were prepared by preparing a bead core injection mold, and having a resin temperature of 3
Under conditions of 00 ° C. and a mold temperature of 100 ° C., a polyphenylene ether resin (VESTO manufactured by Daicel Huls Co., Ltd.) was used.
RAN1900) by injection molding.

For the bead cores of Example 2 and Comparative Example 1, a bead core made of a conventionally used steel wire was used. For the bead apex of Comparative Example 1, a rubber material generally used conventionally was: NR
(RSS # 3 manufactured by Tech Bee Hang Co.) 80 parts by weight, S
BR (SBR150 manufactured by JSR Co., Ltd.)
2: Bead apex comprising 20 parts by weight of styrene unit (23.5% by weight) and 80 parts by weight of carbon black (HAF: Diablock H manufactured by Mitsubishi Chemical Corporation) was used.

(Preparation of Case) A case (carcass ply) made of rubber shown in Table 1 was prepared. In Table 1,
Rubber A uses 70 parts by weight of NR (RSS # 3 manufactured by Techbee Hang Co.) and 30 parts by weight of SBR (SBR1502 manufactured by JSR Corporation; styrene unit amount: 23.5% by weight) as rubber components. And 45 parts by weight of carbon black (HAF: Diablock H manufactured by Mitsubishi Chemical Corporation) and aroma oil (Co., Ltd.)
5 parts by weight of JOMO Process X140 manufactured by Japan Energy, 2 parts by weight of an antioxidant (Nocrack 6C manufactured by Ouchi Shinko Chemical Co., Ltd.), stearic acid (Nippon Oil & Fats Co., Ltd.)
2 parts by weight, zinc flower (zinc flower No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd.) 5 parts by weight, sulfur (powder sulfur manufactured by Tsurumi Chemical Co., Ltd.)
It is a rubber composition obtained by compounding 3 parts by weight and 1 part by weight of a vulcanization accelerator (Noxeller NS manufactured by Ouchi Shinko Chemical Industry Co., Ltd.). Rubber B used 100 parts by weight of NR as a rubber component, and the other components were the same as rubber A.

The case was obtained by mixing rubber A or rubber B with an internal mixer such as Banbury and topping with a case cord material (polyester 1670dex (decitex) / 2 strands).

[0034]

[Table 1]

(Preparation of Tire) Each bead core, bead apex, case and other tire members were bonded together to form a tire. After that, it is vulcanized at 190 ° C,
A radial tire having a tire size of 215 / 45R17 was obtained.

(Evaluation Items of Tires) Weight reduction index Using the tire weight of Comparative Example 1 as a reference (100), an index was indicated using the following formula (weight reduction index). The smaller the index, the lighter the tire.

(Weight reduction index) = (tire weight of each example) ÷
(Tire weight of Comparative Example 1) × 100

Driving stability Each test tire was set at an air pressure of 230 kPa and the displacement was 2
It was mounted on a 000cc FR car, and a feeling test was performed to evaluate the steering stability according to the following criteria. ：: The steering stability is excellent. Δ: Equivalent based on Comparative Example 1.

Ride comfort Each test tire was set at an air pressure of 230 kPa and the displacement was 2
The vehicle was mounted on a 000 cc passenger car and subjected to a feeling test to evaluate the riding comfort according to the following criteria. ：: Very good ride comfort. ：: Excellent ride comfort. Δ: Equivalent based on Comparative Example 1. ×: Poor riding comfort.

(Evaluation results)

[0041]

[Table 2]

Polyphenylene ether is used for the bead core and / or bead apex, and SBR is used for the case.
In Examples 1 and 2, the tires were reduced in weight, the peeling did not occur at the interface between the resin of the bead portion and the case, and the steering stability and riding comfort were good.

The tire of Comparative Example 2 did not undergo an actual vehicle test (evaluation of steering stability and riding comfort) because the bead portion swelled after vulcanization of the tire. The cause is
It is considered that the adhesion between the resin and the case was insufficient.

[0044]

According to the present invention, by replacing the bead core and / or bead apex with a rubber-bonded high-rigidity resin, that is, a polyphenylene ether resin, a pneumatic tire with reduced weight and improved fuel efficiency can be obtained. Obtainable.

Further, the case cord does not undulate around the bead, and the case stretch can be obtained uniformly. Therefore, it is possible to improve steering stability, ride comfort, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a bead portion of a pneumatic tire.

[Explanation of symbols]

 Reference Signs List 1 Bead core 2 Bead apex 3 Carcass ply 4 Chafer 5 Inner liner 6 Side wall 7 Clinch apex

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 AC01W AC02W AC03W AC06W AC07W AC08W AC08X GN01

Claims (2)

[Claims] 1. A bead core and / or a bead apex comprising a polyphenylene ether resin represented by the following structural formula, wherein the rubber composition adjacent to the bead core and / or the bead apex comprises a styrene-butadiene rubber in a rubber component. Pneumatic tire containing 5% by weight or more. Embedded image (Where n represents the degree of polymerization) 2. The pneumatic tire according to claim 1, wherein the styrene unit content of the styrene-butadiene rubber is 15% by weight or more.