JPH08156523A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE: To provide a pneumatic radial tire in which the tire weight can be reduced. CONSTITUTION: This pneumatic radial tire has a carcass 6 extended from a tread part 2 and turned around the bead core 5 of a bead part 4 through a side wall part 3, and engagingly locked in both the ends; and a belt layer 7 formed of belt plies 7A, 7B extended on the tire radial outside of the carcass 6 in the tread inner part, and having belt cords arranged thereon and rubberized. The belt cord is formed by bonding a plurality of filaments (f) by an adhesive containing an urethane group, an epoxy group, or the both without mutually stranding, and covering the surface with a coating agent containing at least resorcinol, formaldehyde, and rubber latex.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire capable of reducing tire weight without increasing passing noise.

[0002]

2. Description of the Related Art In recent years, various lightweight fuel-efficient tires having a smaller rolling resistance have been developed for the purpose of energy saving and efficiency improvement as part of environmental improvement.
Generally, as a method for reducing the weight of tires, the number of each ply such as a carcass layer, a belt layer, and a breaker layer made up of a plurality of plies is reduced from the conventional one such as three to two, or two to one. So called less ply,
In addition to reducing the thickness of the ply topped with a cord with a smaller diameter than before, making the ply thinner less denier, lightening the tread weight by shallow digestion of the tread pattern, etc.
Examples include a method of replacing the band cord with steel having a large specific gravity with an organic fiber cord.

[0003]

The above-mentioned less ply, less denier, less tread weight, etc.
For tire components that are originally necessary, it is a major premise to do so while maintaining their performance.
In particular, the less ply and the reduction in the weight of the tread are nothing but the removal of the flesh to the limit while leaving the tire components left, and there is naturally a limit in achieving a significant reduction in the weight of the tire.

Therefore, another remaining method for reducing the weight of tires is to replace the belt cord used in the belt layer with steel having a large specific gravity with another lightweight alternative material. Although various trials and errors were made, it was difficult to maintain the tire performance equivalent to that of the steel cord, and it was not possible to obtain the basic tire performance requirements such as an increase in tire passing noise due to a decrease in the rigidity of the belt layer, It has not yet succeeded in reality.

As a result of intensive studies in view of the above problems, the present inventor has found a method of raising the organic fiber cord to a rigidity almost equal to that of steel cord, and completed the present invention. Of.

Therefore, according to the present invention, a plurality of filaments are bound together with an adhesive containing a urethane group, an epoxy group or both without being twisted with each other, and the surface is coated with resorcin, formaldehyde, rubber latex, etc. Based on the use of belt cords coated with, it is possible to obtain the rigidity of steel cords even with organic fiber cords, and to reduce the tire weight without increasing passing noise. It is intended to be provided.

[0007]

SUMMARY OF THE INVENTION According to the present invention, at least one carcass having both ends locked by folding back around a bead core of a bead portion from a tread portion to a sidewall portion and radially arranging carcass cords. A pneumatic radial tire comprising a carcass consisting of a ply, and a belt layer consisting of a belt ply that extends outside the tire radial direction of the carcass and inside the tread portion and aligns the belt cords and rubberizes the belt, The belt cord is a coating material in which a plurality of filaments are bound together by an adhesive containing a urethane group, an epoxy group or a urethane group and an epoxy group without being twisted with each other, and the surface contains at least resorcin, formaldehyde and rubber latex. Pneumatic radial tie characterized by being coated with It is.

The filament of the belt cord is
It is desirable that the tensile elastic modulus is 8000 kg / mm ² or more.

[0009]

According to the present invention, the tensile elastic modulus is 8000 kg / mm.
^{Since two} or more filaments are bound together without being twisted together with an adhesive containing a urethane group, an epoxy group, or a urethane group and an epoxy group, belt cords are better than cords obtained by twisting filaments. hand,
As a result of being able to improve strength and elastic modulus, the rigidity of the belt layer can be made almost equal to that using a steel cord,
The tire weight can be greatly reduced without increasing passing noise. In the present application, "to bind the belt cord without twisting a plurality of filaments with each other" means that the plurality of filaments are bound in parallel with each other, and cannot be said to be substantially twisted, It should be understood as meaning that the number of twists per 10 cm of belt cord is less than 1.

Moreover, since the filaments of the belt cord are bound together by using an adhesive without being twisted with each other, the unit length of the cord is longer than that of the twisted cord in which the same number of filaments of the same material are twisted together. The weight per hit is reduced, the amount of cord used is reduced, and the weight of the tire is further reduced.

Further, by coating the surface of the filaments bound with the adhesive with a coating agent containing resorcin, formaldehyde, rubber latex, etc., the adhesiveness when embedded in a rubber composition can be improved. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The pneumatic radial tire 1 of the present invention is folded back from the main body portion 6A extending from the tread portion 2 through the sidewall portion 3 to the bead portion 4 and around the bead core 5 in this example from the inner side to the outer side in the tire axial direction. Carcass 6 consisting of a carcass ply 6a whose both ends are locked by a portion 6B
A belt layer 7 including belt plies 7A and 7B extending outside the carcass 6 in the tire radial direction and inward of the tread portion 2 and having the belt cords 9 aligned and rubberized; It is provided with a bead apex 8 made of hard rubber extending radially outward, and is mainly used as a radial tire for passenger cars.

For the carcass ply 6a, a carcass cord made of an organic fiber such as polyester is used as the tire equator C.
The radial structure is arranged in the rubber composition at an angle of 60 ° to 90 ° with respect to the above, and at least one sheet, in this example, a structure consisting of one sheet is illustrated, but two or more sheets may be provided. Good. The upper edge height h1 of the folded portion 6B of the carcass ply 6a is about 45% of the height H from the bead base line BL to the upper surface of the tread from the bead base line BL when a prescribed internal pressure is filled. The one launched is illustrated. An inner liner 14 that holds the filled air in an airtight manner is attached to the inner surface of the carcass 6 facing the tire inner cavity 12.

The belt layer 7 on the outer side in the tire radial direction of the carcass 6 has a belt cord 9 with respect to the tire equator C.
Two belt plies 7A and 7B arranged at a small angle of 6 ° to 24 °, in this example 20 °, are arranged so that the belt cords cross each other, and the inner belt ply 7A
Is wider than the outer belt ply 7B and each end has a cut-end structure.

As shown in FIG. 2, the belt cord 9 is formed by binding a plurality of monofilament filaments f into one cord by using an adhesive 10 without twisting them.

It has been confirmed that the belt cord 9 in which the filaments f are bundled without being twisted in this way is improved in breaking strength by about 20% as compared with the cord which is twisted.

An organic fiber material having a tensile elastic modulus of 8000 kg / mm ² or more can be preferably used for the filament f. In this embodiment, polyarylate is shown, and the adhesive 10 is as follows. Those containing a urethane group, an epoxy group, or a urethane group and an epoxy group are preferable.

In the belt cord 9, the surface of one cord formed by binding the filaments f with the adhesive 10 is coated with a coating agent 11 capable of improving the adhesive force with the compounded rubber.
The coating material 11 contains at least resorcin, formaldehyde, and rubber latex in its components.

Further, the belt plies 7A and 7B are formed by embedding the belt cords 9 in a rubber composition as an aligned body of the belt cords which are aligned in parallel with each other to form a combed weave.

Further, on the outer side of the belt layer 7 in the radial direction of the tire, a belt-shaped ply of a small width or the like, to which one cord or a plurality of organic fiber cords are topped in parallel in order to prevent the lifting of the belt layer, is formed. A band layer 13 that is spirally wound is provided over.

(Specific example) Tire size is 185 / 70R
Radial tires for passenger cars having 14 and the configuration shown in FIG. 1 were prototyped (Examples 1 to 3), and tire weight, rolling resistance, and tire passing noise were measured. In addition, a plurality of filaments made of polyester are bound together with an adhesive containing urethane groups and epoxy groups without twisting each other, and the surface is coated with a coating agent containing at least resorcin, formaldehyde, and rubber latex. Align the carcass cords, and use this aligned body with butyl rubber or halogenated butyl rubber of 60% or more and 85%
A pneumatic tubeless tire with an inner liner removed by using a carcass ply embedded in a rubber composition containing the following range (Example 4) and a conventional product including a belt layer using a conventional steel cord are also included. I did the test. The test conditions are as follows.

A) Tire weight The weight per tire was measured and expressed as an index with the conventional product as 100. The smaller the value, the lighter the weight.

(B) Rolling resistance It was measured by using a rolling resistance tester and indicated by an index with the conventional product being 100. The smaller the value, the smaller the rolling resistance and the better.

C) Passing noise The test tire is mounted on a test vehicle (Toyota Vista) and IS
The passing noise was measured by traveling on the O road surface at a speed of 70 to 90 km / H. The test results are shown as an index with the conventional product being 100. The smaller the value, the lower the passing noise. The test results are shown in Table 1.

[0025]

[Table 1]

As a result of the test, it was confirmed that the tires of the examples reduced the weight of the tire as compared with the conventional product, had a low rolling resistance, and could maintain the passing noise almost equal to the conventional product.

[0027]

INDUSTRIAL APPLICABILITY As described above, the pneumatic radial tire of the present invention uses a material having a high rigidity as a belt cord and eliminates the use of a steel cord, so that the tire weight can be significantly reduced and the rolling resistance can be improved. Can be reduced and the passing noise level can be maintained.

[Brief description of drawings]

FIG. 1 is a left sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a sectional view for explaining a belt cord.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 9 Belt cord 10 Adhesive 11 Coating agent

Claims (2)

[Claims] 1. A carcass comprising at least one carcass ply in which both ends are locked by folding back around a bead core of a bead part from a tread part to a sidewall part, and the carcass. A radial tire having a belt layer made of a belt ply in which the belt cords are aligned and rubberized and which extend outside in the tire radial direction and inside the tread portion, and the belt cords have a plurality of filaments. Characterized by binding with an adhesive containing a urethane group, an epoxy group or a urethane group and an epoxy group without twisting each other, and coating the surface with a coating agent containing at least resorcin, formaldehyde and rubber latex Pneumatic radial tire to be. 2. The pneumatic radial tire according to claim 1, wherein the filament of the belt cord has a tensile elastic modulus of 8000 kg / mm ² or more.