JPH04123908A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To reduce the weight of a tire and to secure the safety and reliability of a bead by using a bead reinforcing member formed of an organic fiber-resin complex cord meeting a specified condition. CONSTITUTION:A tire is at least provided with a bead 1, bead filler 2, and a carcass ply 3. In this case, an organic fiber-resin complex cord composed of a fiber aggregate formed of an organic fiber practically bundled in mutually parallel and a resin filled in the gap of the fiber aggregate is prepared. In addition to that, the bead 1 is provided with the organic fiber-resin complex cord which has the modulus of longitudinal elasticity of 1000kg/mm<2> or more, tensile strength of 1000kg or more, and the weight ratio of the above resin being within 25-80% by weight to the whole of the organic fiber-resin complex cord as a reinforcing member.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a pneumatic radial tire, and more specifically, the tire itself can be significantly reduced in weight by significantly reducing the weight of the bead and the area around the bead. This invention relates to pneumatic radial tires with improved fuel efficiency.

(Prior Art) Conventionally, as a heat reinforcement body for tires, it is known that, for example, a plurality of hard steel wires coated with rubber are extruded in parallel and then laminated and wound to have a predetermined diameter. .

The cross-sectional shape of this beat reinforcement body may be square, hexagonal, etc.
It has a polygonal shape. As another example, a bead with a circular cross section is also known, in which hard steel wire is spirally wound in multiple layers around an annular core wire.

(Problems to be Solved by the Invention) However, all conventional bead reinforcements use hard steel wire with a specific gravity of approximately 7.8, which increases the weight of the bead reinforcement itself. Therefore, there was a problem that the tire weight increased.

For this reason, attempts have been made to reduce the overall weight of the bead reinforcement by improving the breaking strength of the hard steel wire or by increasing the breaking strength per average cross-sectional area of the bead reinforcement. In all cases, the weight reduction rate of the bead reinforcement was about 10% at most, and the weight reduction rate relative to the entire tire weight was only about 0.3%.

Therefore, the purpose of the present invention is to reduce tire weight and improve rolling resistance by using organic fibers with low specific gravity for bead members, and to improve durability by adopting a bead structure suitable for the organic fiber bead member to be applied. Our objective is to provide a pneumatic radial tire that is also versatile.

(Means for Solving the Problems) The present inventors have conducted extensive studies on how to use organic fibers in the bead portion H without impairing the durability of the tire. The present invention was completed based on the discovery that the reinforcing body needs to have high rigidity as a physical property, and also needs to have a breaking strength of a certain value or more.

However, the present invention is directed to an organic fiber/resin composite consisting of a fiber aggregate made of IJ machine fibers bundled substantially in parallel, and a resin filled in the gaps between the fiber aggregates. and has an elastic modulus of 1000 mm2 or more and a tensile strength of 1000 ++ or more, and the weight ratio of the resin is an organic fiber/resin composite coat. The present invention relates to a pneumatic radial tire characterized in that the heat section is provided with an organic fiber/resin composite cord in an amount of 25 to 80% by weight based on the total weight as a reinforcing material.

In the beat part reinforcing material according to the present invention, only the part corresponding to the core of the heat part is made of metal such as steel, titanium, or inorganic material.
- The organic fiber/resin composite cord may be wound spirally around the cord.

Generally, changing the bead material from steel cord to organic fiber cord particularly lowers the elastic modulus, so increasing the amount of bead filler rubber around the bead may be considered, but in this case, the weight of the tire will increase. This results in a result that goes against the original purpose of the present invention, which is weight reduction.

Therefore, the elastic modulus of the beet filler rubber used in the present invention should be higher, preferably 0.30 kg/mm2 or more, and when cut on a plane passing through the tire center and perpendicular to the tire circumferential direction (see Fig. The cross-sectional area Sg (mm2) of the bead filler rubber (see) is the cross-sectional area S of the bead portion,
(mm”) and the following formula, S − / S b ≦ 3, and the elastic modulus of the bead filler rubber is 1
? , g and the cross-sectional area Sg of the bead filler rubber are expressed by the following formula 3%
It is preferable that the relationship () is satisfied.

In FIG. 1, 1 indicates a bead, 2 indicates a heat filler, and 3 indicates a carcass ply.

In the present invention, high strength and high elastic fibers such as aromatic polyamide fibers (aramid fibers), high strength and high elastic modulus PVA fibers, and liquid crystal polyester fibers can be suitably used as the organic fibers.

Such aromatic polyamide fibers include, for example, poly(],
] 4-phenylene terephthalamyl) fiber, poly-14
-phenylene terephthalamide-3,4'diaminodiphthalamide copolymer fiber, poly(1,4-benzamide) fiber, poly(1,,3-phenylene isophthalamide) fiber, and the like. Among these aromatic polyamide fibers, 1) Kevlar 49.
Kevlar 1.49 (product name) has an elastic modulus of 11ll100 (/mm2) and 14700 (kg/n), respectively.
+m2), which is particularly preferable.

In addition, high strength and high elasticity polyhinyl alcohol (+) VA)
Fibers are produced by spinning from organic solvent-based spinning solutions such as ethylene glycol and glycerin using a semi-dry and semi-wet spinning method.
A high-strength, high-elastic PVA fiber obtained by drawing, which is distinguished from conventional vinylon, has a filament strength of 158/d or more, and has a fiber strength of at least 10% on the surface of the fiber.
The one in which some of the 11 groups have been treated with dehydroxyl groups is preferable because it has excellent fatigue resistance.

For the organic fiber/resin composite coated reinforcement according to the present invention, for example, single fibers are bundled to have a density of 1,500 deniers, liquid bisphenol A epoxy is used as the epoxy resin, and liquid methylhexahydrophthalic anhydride is used as the curing agent. It was well penetrated into a mixture of hensyl dimethylamine as a curing accelerator and a portion of acid-terminated liquid NBR as an elastomer, and then heat-treated at 150°C for 3 minutes to form a fiber-resin composite linear body. can be used.

As the type of resin for embedding the organic fibers, both thermosetting resins and thermoplastic resins can be used.

Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, and bismaleimide resin.

In addition, thermal 0J plastic resins include: ・Nylon, polyester, polyetherethergetone, polycarbonate I
-, polyacecool, polyether sulfone, etc. In addition, a polymer blend using two or more of these may be used, or a blend of a thermosetting resin and a thermal iJJ plastic resin may be used.

(Function) The physical properties of organic fibers that can be used as bead materials in the pneumatic radial tie A of the present invention are compared with those of other cords and are shown in Table 1 below.

No. □-,,,! -,,,,,,-,-As is clear from the large box 1 table, steel coat clearly has a high specific gravity;
This is a major hindrance when trying to reduce the weight of tires. Therefore, it is desirable to use organic fibers with a low specific gravity, but using a material with a low modulus of elasticity will reduce the bead's original role of firmly fixing the tire and rim so that they do not move. Rim slippage occurs when the tire and rim become misaligned while driving due to insufficient performance.

That is, it is absolutely necessary to avoid insufficient tensile rigidity in the bead portion.

Further, in the present invention, it is necessary that the volume of the resin filled in the gaps between the organic fiber aggregates is within the range of 25 to 80% by weight based on the total volume of the cord resin composite.

If the proportion of resin exceeds 80% by weight, the tensile strength will decrease and the volume will become too bulky to obtain the same strength, which is not preferable. Preferably -1- resin ratio is 8
It is 0% by weight or less, more preferably 70% by weight or less. On the other hand, if the resin ratio is less than 25% by weight, the effect of bundling the organic fibers is low and the fibers tend to fray. In order to completely cover the fiber filaments, the volume ratio of the resin is preferably 25% by weight or more, more preferably 35% by weight.
It is more than Jyuashi%.

In addition, because the heating material undergoes large deformation during rimming due to its characteristics as a beet, the double organic woven 1i1/resin composite coat must have a tensile strength of at least 1.000 kg or more. This tensile strength is 10
If the weight is less than 0.00 kg, the heat may break during assembly, so it is extremely important that this condition is not met.

Furthermore, the small volume of bead filler rubber greatly contributes to reducing the weight of the tire, so its volume V9
is preferably less than three times the volume V of the bead portion.

That is, it is preferable that L/V≦3.

For convenience, the cross-sectional area of the bead filler rubber when cut on a plane passing through the center of the tire and perpendicular to the tire circumferential direction (see Figure 1) is assumed to be 39 (mm), and the cross-sectional area of the bead portion is assumed to be 39 (mm). If the area is S b (mm), these are approximately V9/V, , = 39/Sg, so 39/Sg≦
It is preferable to set it to 3.

Further, the elastic modulus of the heat filler rubber is at least 0.3.
0 kg/mm2 or more is required. The bead filler rubber also plays a part in the function of the bead, which is to securely fix the tire to the rim, so having an elastic modulus lower than this allows it to fully demonstrate its function as a bead.
1- is unfavorable.

In addition, if the tensile modulus Eg of the bead filler rubber is high, even if the cross-sectional area Sg of the bead filler rubber is small, it can still perform the function, so the following equation, EgXSg≧15 (kg), can be expressed. It is preferable to reduce 89 within a satisfactory range.

Here, the elastic modulus of beat filler rubber is JIS standard K
A test sample is prepared according to the method according to No. 6301, and the value obtained by dividing the stress value generated when the rubber is elongated by 50% by the cross-sectional area of the sample is shown.

(Example) Next, the present invention will be explained with reference to Examples and Comparative Examples.

Regarding the various bead materials shown in Table 2, type and weight of bead fiber, ratio of thermosetting resin, elastic modulus, strength, bead filler rubber cross-sectional area, bead cross-sectional area, bead filler rubber elastic modulus, bead breakage during rim assembly. The presence or absence of rim displacement was examined.

The strength and modulus of elasticity are measured using one steel cord or organic fiber/resin composite coat 1 that makes up Bea 1'.
Take out the book from the tire and read JIS standard Z 2241:
The elastic modulus is measured using a method similar to the tensile test method for metal materials, and the elastic modulus is calculated from the strength at break and the strength/elongation curve obtained at the same time. This is the value obtained by dividing the stress that would occur under the assumption that the material was elongated by 100% by q"1 by the measured cross-sectional area.

The rim displacement test was performed by marking the tires and rims in advance, and testing the brakes and lanes in the same manner as conducting the steering stability test on a vehicle equipped with 1,655R13 size tires using the sample bead material. After performing various menus such as changing gears and turning at high speed, we checked to see if there was any misalignment between the tire and the rim.

Here, Comparative Example 1 is a normal bead for passenger car tires currently in use, while Example] is an aramid fiber impregnated with an epoxy resin, and the resin and fiber are bonded together. The above-mentioned resin composite fiber cord was spirally wound several times in an annular shape with an inner diameter of approximately 13 inches, with a ratio of resin to the total volume of 40% by weight, and then immersed in RIi L solution and heated at 1.30°C.
165S after drying at 210°C and heat-treating
A bead for an R13 tire was made and a test was conducted on this bead material.

Comparative Example 2 uses organic fibers of aramid fibers as the bead material.
Although a resin composite cord is used, the weight ratio of the resin is 10% by weight based on the entire cord resin composite, which is outside the scope of the present invention. On the other hand, in Comparative Example 3, an organic fiber/resin composite cord of polyester fiber was used as the bead material.

Three types were created with different elastic modulus and amount of rubber.

The following was confirmed from Table 2.

Compared to the case where the steel cord of Comparative Example 2 was used as the bead material, the weight of the bead when the aramid fiber of Example 1 was used as the bead material was about half.

Although the bead weight of both Comparative Examples 2 and 3 was reduced, the tensile strength of Comparative Example 2 was low (the bead broke during rim assembly. On the other hand, the tensile strength of Comparative Example 3 was sufficient, but The elastic modulus was low, causing rim misalignment while driving.

In Example 2, because the elastic modulus of the bead filler rubber was lowered and the amount of bead filler rubber was also reduced, a slight rim shift occurred. On the other hand, in Comparative Example 4, rim displacement occurred because the elastic modulus of the bead filler rubber was too low. Furthermore, in Comparative Example 5, the amount of heat filler rubber was extremely reduced, so SgXEg was as low as 900 kg, and rim displacement was particularly large.

(Effects of the Invention) As explained above, in the pneumatic radial tire of the present invention, the heavy use of the tire is greatly reduced by using the bead reinforcement made of organic fiber/resin composite cords that meet specific conditions. The following effects are achieved: 1) the safety and reliability of the bead is improved;

[Brief explanation of the drawing]

FIG. 1 is a right half sectional view of a pneumatic tire as an example of the present invention, cut along a diagonal plane passing through the center of the tire and perpendicular to the circumferential direction of the tire. 1...Heat 2...Beat filler rubber 3...Carr force sublime

Claims (1)

[Scope of Claims] 1. An organic fiber/resin composite cord consisting of a fiber aggregate in which organic fibers are bundled substantially in parallel, and a resin filled in the gaps between the fiber aggregates, which 1000kg to
An organic fiber having an elastic modulus of /mm^2 or more and a tensile strength of 1000 kg or more, and in which the weight ratio of the above resin is within the range of 25 to 80% by weight based on the entire organic fiber / resin composite cord. A pneumatic radial tire characterized by having a resin composite cord as a reinforcing material in the bead portion. 2. The elastic modulus of the bead filler rubber is 0.30 kg/mm
^2 or more, and the cross-sectional area S_g (mm^2) of the bead filler rubber when cut along a plane passing through the center of the tire and perpendicular to the tire circumferential direction is equal to the cross-sectional area S_b (m
m^2) and the following: satisfies the relationship S_g/S_b≦3, and the elastic modulus E of the bead filler rubber
The pneumatic radial tire according to claim 1, wherein _g and the cross-sectional area S_g of the bead filler rubber satisfy the following relationship: S_g×E_g≧15 (kg).