JP2007145123A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire capable of enhancing the high-speed durability. <P>SOLUTION: As shown in Fig. 1, in the pneumatic radial tire 1, at least one belt reinforcing layer 7 is arranged on the outer circumferential side of a belt layer over the entire belt layer and/or on both ends thereof, and an organic fiber cord of the belt reinforcing layer 7 is spirally wound so as to be substantially parallel in the tire circumferential direction. (a) the size of the filaments of the organic fiber cord is 10-100 decitex, (b) the organic fiber cord is a multi-filament cord with the total size per unit cord being 1,000-6,000 decitex, and (c) the twist coefficient T expressed by the formula (1) of the organic fiber cord: T = TS × ä(TD/2ρ) × 0.139 × 0.9}<SP>1/2</SP>× 10<SP>-3</SP>(where, TS denotes the twist number (twist/10 cm), TD denotes the total size of the cord (decitex), and ρ denotes the density of the cord) is 0.12-0.5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire excellent in high speed durability.

In recent years, with the increase in the size of vehicles and the increase in vehicle types, the tire size has increased and the flatness has decreased. As the tire size increases and the flatness ratio decreases, the burden on the belt layer of the tire increases, and as a result, the conventional belt reinforcement layer using thin filament nylon has sufficiently low tire rigidity to ensure sufficient tire performance. There are some cases where you can't.
In contrast, a tire using a polyethylene naphthalate fiber or an aramid fiber, which is a highly elastic fiber other than nylon, has been devised for the belt reinforcing layer (see Patent Document 1). However, these tires are difficult to apply to general-purpose tires because of low productivity and high cost.
In addition, attempts have been made to increase the elastic modulus and increase the rigidity by reducing the twist of the nylon fiber cord (see Patent Documents 2, 3 and 4). However, when the number of twists is low, the adhesion to rubber may decrease due to filament breakage, and it is difficult to improve the high-speed durability as intended.
Therefore, there is a need for a technology that further improves the high-speed durability of a pneumatic radial tire with an economically advantageous configuration that can suppress the filament breakage of the fiber cord of the belt reinforcing layer and that can increase the rigidity of the belt reinforcing layer. It was rare.

JP 2003-191713 A Japanese Patent Laid-Open No. 7-9809 JP-A-7-81314 Japanese Patent Laid-Open No. 9-30208

  An object of the present invention is to provide a pneumatic radial tire that further improves high-speed durability under such circumstances.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have made the fineness of the filament of the organic fiber cord of the belt reinforcing layer, the total fineness per cord and the twist coefficient within a specific range. We have found that the objective can be achieved.
The present invention has been completed based on such findings.
That is, the present invention
1. A pair of bead portions; a toroidal carcass extending over both bead portions; a tread portion located at a crown portion of the carcass; and a sidewall portion of the carcass; A belt reinforcing layer comprising at least one layer is disposed on the outer peripheral side of the belt layer disposed between the belt layer and at both ends of the belt layer, and the organic fiber cord of the belt reinforcing layer is substantially disposed in the tire circumferential direction. A pneumatic radial tire in which the belt reinforcing layer is formed by being spirally wound so as to be parallel to each other, and (a) the fineness (decitex) of the filament of the organic fiber cord is 10 to 100 (B) Multifilament in which the organic fiber cord is 1000 to 6000 decitex as the total fineness per cord A Ntokodo, and (c) a pneumatic radial tire which twist coefficient T represented by the following general formula of the organic fiber cord (1) is characterized in that it is a 0.12 to 0.5,
General formula (1) T = TS × {(TD / 2ρ) × 0.139 × 0.9} ^1/2 × 10 ⁻³
(Where TS is the number of twists (times / 10 cm), TD is the total fineness of the cord (decitex), and ρ is the density of the cord), and 2. 2. The pneumatic radial tire according to 1 above, wherein the organic fiber cord of the belt reinforcing layer is made of nylon or polyester.
3. The pneumatic radial tire according to 2 above, wherein the organic fiber cord of the belt reinforcing layer is made of 66 nylon or polyethylene terephthalate.

  According to the present invention, it is possible to provide a pneumatic radial tire that further improves high-speed durability.

  The organic fiber cord used in the present invention is not particularly limited as long as the organic fiber cord satisfies the above-mentioned characteristics. As the fiber cord, nylon fiber cords such as 6 nylon and 66 nylon, and polyester fibers such as polyethylene terephthalate. A code etc. can be mentioned. Among them, an organic fiber cord made of 66 nylon or polyethylene terephthalate is preferable from the viewpoints of easily satisfying the above-mentioned characteristics, excellent tire performance requirements, and productivity and cost.

  In the pneumatic radial tire of the present invention, a belt reinforcing layer is disposed on the entire outer periphery and / or both ends of the belt layer, the belt reinforcing layer is made of an organic fiber cord, and rubberized including a plurality of fiber cords. The belt reinforcing layer is preferably formed by winding the narrow strip formed endlessly in a spiral shape so that the cord is substantially parallel to the tire circumferential direction. If the belt reinforcement layer does not have such a spiral structure, a joint can be formed in the tire circumferential direction, so that the tension in the circumferential direction improves rather than between the joints at the joint and the lower layers. Deviation occurs, and no effect is seen even if the code characteristics are limited as described above.

  Moreover, it is important that the fineness of the filament of the organic fiber cord is 10 to 100 dtex, that is, the filament has a larger diameter than before. Thereby, the filament breakage of the organic fiber cord can be suppressed, and the temporal stability of adhesion with rubber can be improved. According to the experiment, it was confirmed that when the fineness of the filament of the organic fiber cord is 10 dtex or more, the temporal stability of the adhesion with the rubber can be improved even with the low twist cord. It was also confirmed that when the fineness of the filament of the organic fiber cord is 100 dtex or less, it is possible to prevent a decrease in initial adhesion with rubber due to a decrease in the amount of adhesive attached to the filament due to a thick filament diameter. .

In relation to the above, in the present invention, the twist coefficient T represented by the general formula (1) of the organic fiber cord of the belt reinforcing layer is required to be 0.12 to 0.5. The lower the twist coefficient T, the higher the elastic modulus of the cord, that is, the higher the rigidity, and the higher the durability of the tire. However, when the twisting coefficient T is less than 0.12, it is difficult to suppress the deterioration of the stability of the adhesive over time due to filament breakage even if the filament diameter is larger than the conventional one. When the twist coefficient T exceeds 0.50, the elastic modulus of the cord is lowered, the belt reinforcing layer cannot be made highly rigid, and the improvement effect of the high speed durability of the tire cannot be expected.
In calculating the twist coefficient T, (number of twist) × (upper twist) indication of the number of twists TS, for example, one number 20 out of 20 × 20 is used. In addition, when the numerical values of the lower twist and the upper twist are different,
Use the value of the upper twist. In the case of only the lower twist, the value of the lower twist is used.

  In addition, if the organic fiber cord of the belt reinforcing layer is a multifilament cord having a total fineness of 1000 to 6000 dtex as a total cord, a highly rigid and lightweight tire can be configured. If it is less than 1000 decitex, a highly rigid belt reinforcing layer cannot be constituted by one layer, and if it exceeds 6000 decitex, the thickness of the belt reinforcing layer increases, resulting in an increase in tire weight. The organic fiber cord of the belt reinforcing layer is preferably a twisted cord.

  As described above, by making the cord of the belt reinforcing layer the optimum filament fineness, the optimum total fineness and the optimum twisting factor, it is economically advantageous, that is, at a lower cost, the high-speed durability of the tire is improved. Can be improved.

Hereinafter, with reference to FIGS. 1-6, the structure of the pneumatic radial tire of this invention is demonstrated in detail. FIGS. 1-6 is sectional drawing of the example from which the pneumatic radial tire of this invention differs, respectively.
1 to 6, a pneumatic radial tire 1 includes a carcass 3 that is folded and locked from the inner side to the outer side of a bead core 2 that occupies a central position of the bead portion, and a tread that is positioned at a crown portion of the carcass 3. Part 5, side wall part 4 of carcass 3, at least two belt layers 6 arranged inside tread part 5, belt layer 6 on the outer periphery side of belt layer 6 and / or on both ends. A belt reinforcing layer 7 composed of at least one layer is provided. The belt reinforcing layer 7 is wound endlessly in a spiral shape (spiral shape) so that the organic fiber cord is substantially parallel to the tire circumferential direction (0 ° to 5 °). The belt reinforcing layer 7 should protrude beyond the belt layer 6 in the radial direction (direction perpendicular to the circumferential direction). The carcass 3 has organic fiber cords arranged substantially in the radial direction, and is composed of at least one layer. In the belt layer 6, non-extensible cords represented by aramid fibers and steel cords are arranged at an inclination angle of 10 ° to 30 ° with respect to the circumferential direction (or the equator plane of the tire), and at least one layer, preferably Two layers of non-extensible cords are superimposed so as to cross in different directions.

  1 to 6 each show an arrangement example of the belt reinforcing layer 7. FIG. 1 is a cross-sectional view of a tire in which a belt reinforcing layer 7 is uniformly wound around the outer peripheral side of the belt layer 6 from the cereal side to the anti-cereal side. FIG. 2 is a cross-sectional view of a tire in which a belt reinforcing layer 7 is wound around both ends on the outer peripheral side of the belt layer 6. In FIG. 3, two layers of the belt reinforcing layer 7 are similarly wound around both ends on the outer peripheral side of the belt layer 6. FIG. 4 is a cross-sectional view of a tire in which a belt reinforcing layer 7 is wound around the entire outer peripheral side of the belt layer 6 and a belt reinforcing layer 7 is further wound around both ends on the outer peripheral side. 5 and 6 are cross-sectional views of a tire in which the belt reinforcing layer 7 is wound around one layer on the entire tread portion and two layers on both ends, and two layers on the entire tread portion and one layer on both ends.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The tires used in Examples 1 to 4 and Comparative Examples 1 to 4 described later are as follows. The tire size used is a tubeless structure of 205 / 65R15, and the carcass is polyester (polyethylene) having a twist number of 1670 dtex / 2 (twisted 1670 dtex) (primary twist x upper twist) 40 x 40 (times / 10 cm). A terephthalate) cord was placed with a number of driven wires of 10/10 cm, and one layer was disposed at an angle of 0 ° with the radial direction. As the belt layer, two steel cord belts having a structure of 1 × 5 × 0.25 mm were arranged, the driving angle was 20 ° on the left and right with respect to the circumferential direction, and the number of driving was 80/10 cm. The belt reinforcing layer was spirally wound around the outer side of the belt layer at an angle of 0 to 5 ° with respect to the circumferential direction at 100 pieces / 10 cm. The belt reinforcing layer was arranged as shown in FIG. At this time, the belt reinforcing layer was wound around the entire outer peripheral side of the belt layer by 5 mm wide at both ends on the outer side in the radial direction of the belt layer. Then, a belt reinforcement layer was further wound around both ends on the outer peripheral side of the belt reinforcing layer so as to cover both ends on the outer peripheral side of the belt layer. This two-layer belt reinforcing layer was formed as described above using a strip having a narrow width of about 5 to 20 mm.

Resorcin-formalin condensate / latex (RFL) was used as an adhesive for adhesion to rubber. Here, RFL is adjusted to the following composition and aged for 24 hours or more.
・ Water 559 (parts by mass)
・ Resorcin 17
・ Formalin (37%) 22
・ Sodium hydroxide 2
・ Vinylpyridine-styrene-butadiene copolymer latex (41%) 400
First, after immersing the twisted yarn cord in this adhesive, an adhesive treatment cord can be obtained by performing a normal heat setting treatment.

Examples 1-4, Comparative Examples 1-4
Eight types of pneumatic radial tires having belt reinforcement layers shown in Table 1 were produced. Polyethylene terephthalate was used as the polyester fiber for the belt reinforcing layer. The density of 66 nylon was 1.14 kg / L, and the density of polyethylene terephthalate was 1.39 kg / L. As an evaluation of the high-speed durability of these tires, the vehicle was run at 150% load, which is the maximum load condition of JATMA, and the speed was increased by 10 km / h every hour. As an index. The higher the index, the better the high speed durability.

  As is clear from Table 1, the pneumatic radial tires of Examples 1 to 4 all showed improved high-speed durability.

  The pneumatic radial tire of the present invention effectively improves high-speed durability with the economically advantageous configuration described above, and thus various air for passenger cars, small trucks, light passenger cars, light trucks and large vehicles. Widely and suitably used as a radial tire.

It is sectional drawing which shows one Example of the pneumatic radial tire of this invention. It is sectional drawing which shows the other Example of the pneumatic radial tire of this invention. It is sectional drawing which shows the other Example of the pneumatic radial tire of this invention. It is sectional drawing which shows the other Example of the pneumatic radial tire of this invention. It is sectional drawing which shows the other Example of the pneumatic radial tire of this invention. It is sectional drawing which shows the other Example of the pneumatic radial tire of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic radial tire 2 Bead core 3 Carcass 4 Side wall part 5 Tread part 6 Belt layer 7 Belt reinforcement layer

Claims (3)

A pair of bead portions; a toroidal carcass extending over both bead portions; a tread portion located at a crown portion of the carcass; and a sidewall portion of the carcass; A belt reinforcing layer comprising at least one layer is disposed on the outer peripheral side of the belt layer disposed between the belt layer and at both ends of the belt layer, and the organic fiber cord of the belt reinforcing layer is substantially disposed in the tire circumferential direction. A pneumatic radial tire in which the belt reinforcing layer is formed by winding in a spiral shape so as to be parallel,
(A) The fineness of the filament of the organic fiber cord is 10 to 100 dtex, and (b) the organic fiber cord is a multifilament cord having a total fineness per cord of 1000 to 6000 dtex, And (c) a pneumatic radial tire characterized in that the twist coefficient T represented by the following general formula (1) of the organic fiber cord is 0.12 to 0.5.
General formula (1) T = TS × {(TD / 2ρ) × 0.139 × 0.9} ^1/2 × 10 ⁻³
(In the formula, TS is the number of twists (times / 10 cm), TD is the total fineness of the cord (decitex), and ρ is the density of the cord.)   The pneumatic radial tire according to claim 1, wherein the organic fiber cord of the belt reinforcing layer is made of nylon or polyester.   The pneumatic radial tire according to claim 2, wherein the organic fiber cord of the belt reinforcing layer is made of 66 nylon or polyethylene terephthalate.

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