JPS6226103A - Radial tire reinforced with carbon fiber - Google Patents

Abstract

PURPOSE:To make improvements in corrosion resistance, high-speed durability and driving comfortableness, by setting up a cap ply part consisting of a thermal contractible organic fiber cord between an outermost layer of belt parts having carbon fiber cord embedded layers of more than one ply and a tread part. CONSTITUTION:A belt part 2 is made up of combining more than one ply of carbon fiber cord layers embedded in rubber of 30kg/cm<2>-60kg/cm<2> in 100% modulus in parallel at a small angle with the circumferential direction. And, a cap ply part 3, disposing thermal contractible organic fiber cords parallelly in a tire circumferential direction, is set up between an outermost layer of this belt part 2 and a tread part 4. With this constitution, corrosion resistance, high-speed durability and driving comfortableness are all improved without entailing any damage to abrasion resistance and steerability and, what is more, crushability in a carbon fiber is improvable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improved radial tire having a belt layer made of carbon fiber cords and a cap ply layer made of a heat-shrinkable organic fiber material.

(Prior art) Conventionally, steel belt radial tires have extremely superior wear resistance and maneuverability because steel has a higher modulus than aromatic polyamide, rayon, glass fiber, etc. It has the same drawbacks as the opposite method.

That is, the disadvantages are: [1] Moisture such as rainwater that enters from the traumatized area progresses corrosion of the steel cord, which reduces the adhesion between the cord and the rubber or reduces the fatigue resistance of the cord, leading to tire failure.

(2) Compared to aromatic polyamide, rayon, glass fiber, etc., steel is extremely heavy at the same tensile strength, so the weight of the belt increases, and the centrifugal force during running causes the scunding wave to Easily occurs and has poor high-speed durability. (3) Compared to aromatic polyamide, rayon, glass fiber, etc., steel has high bending rigidity, so the bending rigidity of the tread section is high, and the vibration ride quality when the tire rides over protrusions on the road surface. is inferior.

In order to improve these disadvantages of steel belt radial tires, we have used flexible carbon fiber cords as adhesives for tire belt components, which have high specific strength and specific modulus, are thermally and chemically stable, and have low bending rigidity. Japanese Patent Publication No. 56-40043 discloses a pneumatic tire reinforced with carbon fiber, which is characterized in that it can be used through Fractures will occur and the belt will be destroyed.
There was a problem in that the tire life was significantly reduced.

The purpose of the present invention is to improve corrosion resistance, high-speed durability, and ride comfort, without sacrificing the inherent advantages of steel radial tires that use only steel cords for the belt, such as wear resistance and maneuverability, while improving the corrosion resistance, high-speed durability, and riding comfort that are disadvantageous to these tires. The objective is to improve the carbon fiber and further improve the friability problem peculiar to carbon fiber.

(Means for Solving the Problems) As a result of extensive research into radial tires having a carbon fiber cord belt layer in order to solve the above problems, the present inventors found that at least one layer of the carbon fiber cord belt layer At least one cap ply layer made of cords of heat-shrinkable organic fiber material arranged approximately in the circumferential direction of the tire is disposed between the outermost belt layer and the tread layer; Confirm that the objective can be achieved by specifying the % modulus,
The present invention has been achieved.

That is, the present invention provides a carcass comprising a tread portion, a pair of side portions connected to both shoulders of the tread portion, and a pair of bead portions formed on the inner periphery of these side portions, and reinforced with a belt embedded inside the tread portion. In a radial tire having a carbon fiber cord of 30 kg/cm2 to 60 kg/cI11 in at least one layer of the belt layer,
A belt layer is embedded in rubber having a modulus and arranged in parallel at a small angle with respect to the circumferential direction, and between the outermost layer of the belt layer and the tread portion, a layer is placed approximately parallel to the tire circumferential direction. The present invention relates to a radial tire characterized by having at least one cap ply layer in which cords made of a heat-shrinkable organic fiber material are arranged in parallel and embedded in rubber.

The configuration of the present invention will be explained in detail below.

The carbon fibers used in the present invention may be, for example, carbonized fibers obtained by firing polyacrylic fibers, or carbonized fibers obtained using pitch from petroleum, coal, or the like as a raw material. The cord made of carbon fiber filaments is treated with an adhesive for adhesion to the rubber. For adhesive treatment, a mixed adhesive of resorcinol-formalin resin and latex (RFL
), but it is preferable to add rubber latex to the water-soluble epoxy compound treatment solution in the first stage. After this, the treated system is subjected to a dry heat treatment, and then the treated system is pre-twisted in the usual manner, a plurality of the strands (usually two) are aligned, and a final twist is applied in the opposite direction to the first twist.

At least one belt layer is used in which the carbon fiber cords obtained in this manner are embedded in rubber having a 100% modulus of 30 kg/cI11 to 60 kg/cd in parallel at a small angle to the circumferential direction. The 100% modulus of the embedded rubber is 30 kg/crl to 60 kg/cl [I is required because if it is less than 30 kg/crl, the rigidity of the belt will decrease, resulting in a decrease in tire wear resistance and handling stability. At the same time, fragmentation of the carbon fiber cord filament occurs, and on the other hand, if it exceeds 60 kg/cm2, the modulus is too high and the belt layer becomes hard, resulting in poor tire riding comfort.

A plurality of the carbon fiber belt layers may be used in an alternately crossed manner, or may be used in combination with a steel cord belt layer. In a preferred example in which the carbon fiber belt layer and the steel cord belt layer are used in combination, a first belt layer in which steel cords arranged on the carcass side are embedded in parallel in rubber, and a radially outer side of the first belt layer are provided. A second belt layer made of carbon fiber cord belt layers arranged so as to cross the cord direction of the first belt layer is used in combination. Further, the end portions of the carbon fiber cord belt layer may be used by being separated, or may be used by being folded back.

Next, a cap ply layer in which cords made of a heat-shrinkable organic fiber material are arranged substantially parallel to the tire circumferential direction is arranged between the outermost layer of the belt layer and the tread portion. This cap ply layer is -1i! Q is a reinforcing layer placed for the purpose of increasing the circumferential rigidity of the belt in order to improve the high-speed durability of the tire, and heat-shrinkable organic fiber materials include C, nylon cord, rayon cord, Although a polyester cord or the like is used, a polyhexamethylene adipamide fiber (66 nylon) cord is preferably used.

By the way, the present inventors have proposed that by arranging this cap ply layer in a tire using a carbon fiber cord belt layer, compressive strain due to buckling of the belt layer that occurs behind the ground contact area during tire cornering, or small protrusions on the road surface. It was confirmed that the compressive strain that occurs in the belt layer when passing over the belt, and the interlayer shear strain that occurs at the end of the belt are alleviated, thereby suppressing the fracture phenomenon of the carbon fiber cord filament. That is, in the present invention, the cap ply layer is arranged for the purpose of improving the high-speed durability of the tire and at the same time protecting the carbon fiber belt layer from human force applied from the tread portion. For this purpose, the width of the cap ply layer in the tire radial direction is preferably greater than the maximum width of the belt layer and preferably covers the entire belt layer. FIG. 1 is a partially cutaway perspective view of this preferred example of the tire of the present invention.
1 is a carcass part, 2 is a belt part, 3 is a cap ply part, 4 is a tread part, 5 is a side part, and 6 is a bead part. As shown in the figure, the width of the cap ply layer 3 in the tire radial direction is larger than the maximum width of the belt layer 2 and covers the entire belt layer, but it does not necessarily have to be larger than the maximum width of the belt layer 2. . In carbon fiber cord belt tires without the cap ply layer, at the end of tire running, especially when most of the tread is worn out, the compressive strain on the carbon fiber cord belt layer becomes large during cornering or when wrapping around small protrusions, causing the tread to deteriorate. This causes the carbon fiber cord filament at the bottom of the groove to break.

(Example) The invention will be explained in more detail by the following examples.

EXAMPLES Ten types of Example tires, Comparative Example tires, and conventional tires of tire size 195/70HR14 having the structures of the belt layer and cap ply layer shown in Table 1 were made. Incidentally, polyester cord 1000 D/2 2-bray was used for the carcass ply cord of these tires.

In addition, all carbon fiber cords in the table are 1800 D/2,
A steel seed with a twist number of 5 x 5 and an initial modulus of 600 g/D was used, and all steel seeds had a 1 x 5 x 0.23 structure and an initial modulus of 1.8 x lO' (kg/order 2). The angle of the carcass cord is 0° with respect to the tire radial direction, the angle of the belt cord is 306 with respect to the circumferential direction for both the carbon fiber cord and the steel cord, and the first layer,
The cord arrangement directions of the second layer were set to intersect with each other. Further, the angle of the cap ply cord was set to 0° with respect to the tire circumferential direction.

The test items and methods are as shown below, and the results are expressed as an index, with the result of the conventional tire set as 100.

○Abrasion resistance: Field test The amount of wear on the tread was measured after running 40,000 km.

○ Cornering force was measured on the drum and compared in terms of the magnitude of the cornering power.

Vibration ride comfort: A test driver conducted a feeling test on a test course on a gravel road, stone piles, and relay circuits.

O High speed durability Nidram test US standard F? JVSS No.
, according to the 109 high speed test, internal pressure 2.1 kg/cm2, load JIS load, rim size 5'/2 JJX14 at a speed of 81 km/h.
After running for 0 minutes, it was left to cool for 3 hours. 30 each from i21 km/h
I stepped up the speed by about 8 km/h minute by minute, and ran the car until the tire broke. The evaluation was based on the speed test and driving time at the time of tire failure.

○ In the crush resistance Ni-dram test, the belt was run under a constant load and speed with a slip angle applied so that compressive strain was applied to the belt, and the state of filament fracture in the carbon fiber cord after running was evaluated.

As shown in Table 1, No. 1 is the tire of the present invention.

1. The wear resistance of tires 2, 7, and 8.9 (example) is
No. 10, a conventional steel belt radial tire
This tire is equivalent to the previous tire (conventional example), and has significantly improved maneuverability, vibration riding comfort, and high-speed durability.

Even with the carbon fiber cord belt layer, 100% of the embedded rubber
% modulus is 30kg/an! If less than No. 3
The tire (comparative example) is inferior in terms of wear resistance and maneuverability, and also inferior in belt crushing resistance. In addition, if the 100% modulus of the embedded rubber exceeds 60 kg/cnf, a tire with Nα4 (
Comparative example) does not have good ride comfort.

Furthermore, it can be seen that in the case where there is no cap briquette cord layer, such as in the tires with Nα5 and 6 (comparative examples), the crushing resistance of the carbon fiber belt cord is poor. Furthermore, when there are two cap pride layers, No. 7 tire (example),
Tire No. 8 using nylon 6 (example)
Both have good belt cord crush resistance.

(Effects of the Invention) As explained above, according to the present invention, in a radial tire, a carbon fiber cord belt layer with a small number of layers is used, the 100% modulus of the embedded rubber is specified, and the outermost layer is By arranging at least one cap ply layer in which cords made of a heat-shrinkable organic fiber material are arranged between the belt layer and the tread, the abrasion resistance and maneuverability that are the advantages of conventional steel radial tires are maintained. However, it is possible to improve ride comfort and high-speed durability, which are disadvantageous, and also to improve the problem of crush resistance peculiar to carbon fiber cords.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of the tire of the present invention. 1...Carcass part 2...Belt part 3...Cap braai part 4...Tread part 5...Side part 6...Bead part

Claims (1)

[Scope of Claims] 1. Comprising a tread portion, a pair of side portions connected to both shoulders of the tread portion, and a pair of bead portions formed on the inner periphery of these side portions, and reinforced with a belt buried inside the tread portion. In a radial tire having a carcass with a carbon fiber cord of 30 kg/cm^2 to 60 kg/cm^2 in at least one layer of the belt layer,
A belt layer embedded in rubber having a modulus of 0.00% and arranged in parallel at a small angle to the circumferential direction is used, and between the outermost layer of the belt layer and the tread part, A radial tire reinforced with carbon fiber, characterized in that at least one cap ply layer is arranged in which cords made of heat-shrinkable organic fiber material are arranged in parallel and embedded in rubber in a substantially parallel manner. 2. The belt layer in which the carbon fiber cords are embedded in the rubber is composed of two cord layers in which the cords between the layers intersect with each other, and the cords of the cap ply layer are made of polyhexamethylene adipamide fibers. A radial tire according to claim 1. 3. The radial tire according to claim 2, wherein the cap ply layer consists of two layers. 4. The belt layer includes a first belt layer in which steel cords placed on the carcass side are embedded in parallel in rubber;
30 kg of the above-mentioned carbon fiber cords arranged on the outside in the radial direction of the belt layer so as to intersect with the cord direction of the first belt layer.
Claim 1 comprising a second belt layer embedded in a rubber having a 100% modulus of /cm^2 to 60 kg/cm^2 and arranged in parallel at a small angle to the circumferential direction. radial tire.