JPH06226870A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire capable of displaying stable air seal property in protection from air leakage to be generated by treading nails, without degrading productivity. CONSTITUTION:A pneumatic tire 1 comprises a toroidal carcass consisting of at least one ply of a rubber coated layer of organic fiber cord arranged substantially in parallel with a flat face including a rotation axis of the tire. On the outer periphery of a crown 3 of the carcass 2, a belt 4 and 2 tread 5 are provided. An inner liner 6 is arranged on the inner periphery of the carcass 2 and a sealant layer 7 is arranged on the inner periphery of the belt 4. The ply of the carcass 2 has a wavy shape in the flat face at the crown 3 of the carcass 2. The sealant layer 7 is divided into two parts by the wavy ply so as to make an alternate arrangement along the direction of the width of the tire, pinching the ply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of exhibiting a stable sealing property against air leakage caused by nailing or the like by properly disposing a sealant layer on the crown portion of the tire. It is a thing.

[0002]

2. Description of the Related Art Pneumatic tires are
May be damaged such as nailing. If this damage reaches the inside of the tire, air leakage occurs, and especially when this air leakage occurs during high-speed traveling, there is a concern that a serious accident will occur.

Therefore, in order to ensure safety, studies are being made on prevention of air leakage. For example, it is known that it is useful to arrange a sealant layer with a constant thickness on the inner surface of the crown portion of the carcass of the tire. Specifically, even if nails etc. penetrate into the pneumatic tire and reach the inside of the tire, air leakage usually occurs due to this nail step portion, but if this nail step portion can be blocked by the sealant layer, air leakage will occur. Can be prevented.
The sealant layer is generally placed in a layer between the carcass ply and the inner liner, or between the inner liner and the additional liner.

[0004]

However, in a pneumatic tire having a sealant layer disposed between the above layers, the thickness of the sealant layer across the width of the crown portion of the tire is undesired due to the flow of the sealant substance due to centrifugal force generated during running. It becomes uniform, and as a result, a reliable air sealing property may not be obtained depending on the position where the nail sticks.

Further, in order to make the air-tightness of the pneumatic tire more reliable, it is known that a partition such as a partition wall may be provided in the sealant layer to suppress the flow of the sealant substance. However, there are disadvantages such as the need for a new member for use and a reduction in productivity due to the shape and arrangement of the new member.

In view of the above, the present invention provides a pneumatic method capable of suppressing the flow of a sealing material that tends to occur during running and maintaining a constant thickness of the sealant material over the entire crown portion of the tire without lowering productivity. The purpose of this is to develop a tire so that the air sealability can be stably exhibited against air leakage due to nail stepping and the like.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a toroidal carcass comprising at least one ply of a rubberized layer of organic fiber cords arranged substantially parallel to a plane containing the tire's axis of rotation. , The outer periphery of the crown portion of this carcass is provided with a belt in which at least two layers of cord rubberized layers are crossed and the tread portion reinforced by this belt, and the inner liner is provided on the inner periphery side of the carcass, and the inner periphery of the belt. In a pneumatic tire in which a sealant layer is disposed on each side, one of the plies of the carcass has a corrugated shape in the plane at the crown portion of the carcass, and the sealant layer is formed with the corrugated ply. The pneumatic tire is characterized in that the plies are sandwiched by being divided into two parts so as to be alternately arranged along the tire width direction.

FIG. 1 shows an example of a sectional structure of the pneumatic tire of the present invention taken along a plane including the rotational axis of the tire.
In the figure, 1 is a pneumatic tire, 2 is a carcass, 3 is a crown portion, 4 is a belt, 5 is a tread portion, 6 is an inner liner, and 7 is a sealant layer. In the illustrated pneumatic tire 1, a carcass 2 has a toroidal shape and is composed of at least one ply of a rubberized layer of organic fiber cords arranged substantially in parallel with a plane including a rotation axis of the tire. As the material of the organic fiber cord, polyester, aramid, nylon and the like are mainly preferable. The carcass 2 is preferably composed of two or more plies. Of these, two plies are one ply having a corrugated cross-sectional shape at the crown portion 3 of the carcass 2 and the other one ply having a normal shape. Preferably.

The sealant layer 7 includes a belt 4 and a carcass 2.
In order to prevent the flow of the sealant substance, it is preferable that the sealant substance is disposed between any two members of the ply and the inner liner 6 to seal the sealant substance between these members. The enclosed sealant material is further divided into two halves along the tire width direction by the ply of the carcass 2 having the corrugation, and the corrugated plies are adjacent to each other at the maximum peak positions in the radial direction of the tire. Since the plies are in close contact with each other, they are alternately arranged in the tire width direction with the plies sandwiched therebetween. It is preferable that the sealant materials arranged alternately have an overlapping portion on the widthwise end side thereof along the radial direction of the tire.

The sealant material includes polyethylene, polypropylene, polybutadiene, polyisoprene, polyisoprene-butadiene copolymer, polystyrene-butadiene copolymer, butyl rubber, halogenated butyl rubber, acrylonitrile-butadiene copolymer, silicone rubber and thermoplastic resin. It is preferable to be composed of one kind or two or more kinds selected from the above, and if necessary, an adhesive, a softening agent, a filler and the like may be blended. Further, it may have a cross-linking structure by any one of the cross-linking methods of sulfur cross-linking, peroxide cross-linking and photo-cross-linking, and a vulcanizing agent, a peroxide cross-linking agent, a photo-crosslinking agent, etc. may be appropriately blended. it can. The viscosity of the sealant material is 6 × 10 4 poise or less at 60 ° C., 10
It is preferable that it has fluidity at a temperature of not less than ° C. This is because if the viscosity is too high, a sufficient sealing effect cannot be obtained. The viscosity is measured by spectrometer RVE
(Manufactured by Rheometrics).

The belt 4 is composed of at least two cord rubberized layers which are cross-laminated, steel cords having a normal twist structure are used for the cords, and the cord arrangement of each cord rubberized layer is the tire equator. It was arranged to be inclined in the opposite direction to the plane. For the inner liner 6, a normal butyl rubber was used.

[0012]

According to the present invention, the sealant layer 7 is disposed between any two members of the belt 4, the ply of the carcass 2 and the member of the inner liner 6, and in particular, the ply of the carcass 2 having a corrugated shape. By partitioning, the flow of the sealant substance can be suppressed even when centrifugal force is generated during traveling, so that the sealant substance can be retained at a predetermined position, and the sealant layer 7 has a uniform thickness over the entire crown portion of the tire. Can be maintained. Moreover, since the ply of the carcass 2 is used as a member for partitioning the sealant layer 7, it is not necessary to select the shape and arrangement of the partitioning member, which has been complicated until now.

[0013]

EXAMPLE A pneumatic radial tire for passenger cars having a tire size of 275 / 40ZR17 was tested as a test tire. Examples 1 to 6 are invention tires having a tire width cross section shown in FIG. 1, and a conventional example is composed of one ply having a carcass having a normal shape as shown in FIG. 2, and a sealant layer is arranged between this ply and an inner liner. A conventional tire having a tire width cross section described above and a comparative example are a comparative tire having a tire width cross section shown in FIG. 1 and using a sealant material having high viscosity.

The invention tire having the tire structure shown in FIG. 1 has a toroidal shape consisting of two plies of a rubberized layer of polyester cords (1500d / 2) arranged at 0 ° with respect to the plane including the rotation axis of the tire. An inner peripheral side of the carcass 2 is provided with a carcass 2 and a belt 4 having a crossed arrangement of two layers of cord rubber and a tread portion 5 reinforced by the belt 4 on the outer periphery of a crown portion 3 of the carcass 2. Is provided with an inner liner 6 and a sealant layer 7 is provided on the inner peripheral side of the belt 4. The cord rubberized layer forming the belt 4 was a steel cord having a 1 × 5 twist structure, and the cords were arranged at an angle of 25 ° with respect to the tire equatorial plane. One of the plies of the carcass 2 has a corrugated shape in a plane including the rotation axis of the tire at the crown portion 3 of the carcass 2 (a peak-to-peak width W between peaks and valleys is 2 mm, and a peak-to-peak interval is one cycle). Distance T is 70m
m), and the sealant layer 7 is divided into two parts by the corrugated ply so that the ply is sandwiched and the sealant material is alternately arranged along the tire width direction. The alternately arranged sealant substances were arranged to have overlapping portions on the widthwise end sides thereof along the tire radial direction.

The types of viscous materials used for the sealant layer 7 are as follows. RB805 (manufactured by JSR) is used for syndiotactic 1,2 polybutadiene, and SIS5000 (J is used for styrene-isoprene thermoplastic resin).
SR made) and IR2200 (JS
R manufactured by R Co., and EH5520U (JS
R), LIR50 (Kuraray) for liquid isoprene, and KR for styrene-olefin thermoplastic resin.
ATON G1657 (manufactured by Shell Chemical Co., Ltd.), and dicumyl peroxide, Park Mill D (manufactured by NOF Corporation),
Irgacure 651 (manufactured by Ciba-Geigy) was used for benzyl dimethyl ketal, and A-TMPT (manufactured by Shin-Nakamura Chemical) was used for trimethylolpropane triacrylate. Sealant layer 7 of the pneumatic tire used in this test
The above viscous materials are blended in the proportions shown in Table 1, respectively. In Table 1, the presence or absence of crosslinking and the viscosity (60
(° C.) and the average thickness of the sealant layer 7 are also added.

[0016]

[Table 1]

The conventional tire used in the conventional example has a carcass composed of one ply having a normal shape as shown in FIG. 2, and has a tire width cross section in which a sealant layer is arranged between the ply and the inner liner. The structure is the same as the invention tire shown in FIG. 1, and the comparison tire used in the comparative example is the same as the invention tire shown in FIG. 1 except that a sealant material having a high viscosity is used.

Next, the test method will be described. In the test, the test tire was mounted on the rear of the vehicle, and a nail (diameter 3 mm, length 65 mm) was driven into the test tire until it reached the inside of the tire at the point P shown in FIGS. At a mean speed of 100 km / h and running around a 3.5 km circuit, checking the tire internal pressure every three hours, and measuring the running distance when the initial internal pressure of 240 kPa dropped to 140 kPa. evaluated. The results of these tests are shown in Table 2.

[0019]

[Table 2]

From these test results, Example 1 exhibited an excellent air-sealing property even under high-speed running conditions in which the sealant substance was liable to flow, as compared with the conventional example and the comparative example. Further, Examples 2 to 6 in which the conditions of the composition of the viscous material used for the sealant substance, the presence or absence of crosslinking, and the viscosity (60 ° C.) were changed within the proper range also showed excellent air sealability.

[0021]

According to the present invention, the sealant layer 7 is disposed between any two members of the belt 4, the ply of the carcass 2 and the member of the inner liner 6, and the ply of the carcass 2 is further corrugated. By partitioning with, since the flow of the sealant substance can be suppressed even when centrifugal force is generated during traveling, the sealant substance can be retained at a predetermined position, and the sealant layer 7 covers the entire crown portion of the tire (particularly the tire). A uniform thickness can be maintained over the width direction. Therefore, no matter where the nail or the like is stuck in the crown portion of the tire, since the sealant layer is uniformly present over the entire crown portion of the tire, it is possible to quickly block air leakage due to nail stepping and the like, which is stable. Air sealability can be obtained. Further, since the carcass ply is used as a member for partitioning the sealant layer 7, it is not necessary to select the shape and arrangement of the partitioning member, which has been complicated until now, and the productivity is improved.

[Brief description of drawings]

FIG. 1 is a width sectional view of a main part of a pneumatic tire used in Examples 1 to 6 and Comparative Example.

FIG. 2 is a width sectional view of a main part of a pneumatic tire used in a conventional example.

[Explanation of symbols]

 1,11 Pneumatic tire 2 Carcass 3 Crown part 4 Belt 5 Tread part 6 Inner liner 7 Sealant layer P Nail driving position T Peak-to-peak distance in one cycle W Peak-to-peak width

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Claims (1)

[Claims] 1. A toroidal carcass comprising at least one ply of a rubberized layer of organic fiber cords arranged substantially parallel to a plane including a rotation axis of a tire,
On the outer circumference of the crown portion of this carcass, a belt in which at least two cord rubberized layers are arranged in an intersecting arrangement and a tread portion reinforced by this belt are provided, an inner liner is provided on the inner circumferential side of the carcass, and an inner circumferential side of the belt is provided. In a pneumatic tire having a sealant layer respectively arranged, one of the plies of the carcass has a corrugated shape in the plane at the crown portion of the carcass, and the sealant layer is formed with the corrugated ply, A pneumatic tire characterized in that the ply is sandwiched by being divided into two parts so as to be alternately arranged along the tire width direction.