JP3510811B2 - Pneumatic tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubeless pneumatic tire capable of suppressing air leakage from a tread sting due to nailing or the like.

[0002]

2. Description of the Related Art As one of means for preventing air leakage from a punctured portion caused by nailing or the like, as shown in FIG. 8, for example, an inner liner facing a tire inner cavity is known. A bag-shaped portion c is formed between the rubber a and a sealing rubber sheet b attached to the inside thereof, and after the tire is vulcanized and molded, a puncture sealing agent is injected into the bag-shaped portion c such as a syringe f. There has been proposed a method of injecting by using (for example, Japanese Patent Laid-Open No. 8-323875).

This bag-shaped portion c is formed by stacking the sealing rubber sheet b and the inner liner rubber a in the green tire forming step, leaving talc and the like on both sides of the inner surface of the sealing rubber sheet b. The powdery or liquid mold release agent is applied in advance, and both sides of the sealing rubber sheet b and the inner liner rubber a are vulcanized and adhered at the time of vulcanization molding, so that only the mold release agent applied part is formed. Is formed by peeling.

In such a pneumatic tire t, the sealing rubber sheet b is adhered to the inner liner rubber a only on both sides even after vulcanization in order to form the bag portion c.
However, as a result of various experiments conducted by the inventors, as shown in FIG. 9 which is an XX cross section of FIG. 8, the sealing rubber sheet b is wavy in the tire circumferential direction after vulcanization and has a poor finish. It was found that This is because the sealing rubber sheet b has a remarkably large elongation rate per unit force as compared with the carcass ply g, the breaker ply h, and the like in which the sealing rubber sheet b is reinforced by the fiber cords and the like arranged on the tire radial direction outer side of the tire. Also, in the sealing rubber sheet b, there is a large gap between the circumference during tire molding and the circumference during expansion and deformation by being pressed against the mold during the vulcanization step,
It is considered that this is because the sealing rubber sheet b remains as a difference between stretching (expansion) during vulcanization and shrink (shrinkage) after vulcanization.

Such a corrugation phenomenon of the sealing rubber sheet b makes the void (radial direction) dimension of the bag-like portion c non-uniform in the tire circumferential direction, and thus it becomes difficult to uniformly fill the sealing agent. However, it has been pointed out that air tends to remain when the sealant is injected, which causes a problem that the puncture sealing performance of the tire itself is deteriorated.

The present invention has been devised in view of the above problems, and can suppress the corrugation of the bag-shaped portion (non-adhesive portion) and the like, can be formed accurately and stably, and can be used as a sealant. It is an object of the present invention to provide a pneumatic tire capable of producing a high-quality tire having a high yield and a high yield and efficiency.

[0007]

In order to achieve the above object, the invention according to claim 1 comprises a toroidal carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion and the tread. A pneumatic tire in which a puncture-preventing sealant extending in the tire circumferential direction is arranged inside the portion, wherein the carcass is a tread portion.
From the side wall to the bead, and
And two plies that are located inside the tire radial direction
It is possible to form a bag-shaped portion for containing the sealant and to the cord.
Therefore, it has one or more reinforced sealing plies ,
And the ply for sealing and the ply on the outside are integrally formed.
Adhesive parts to be adhered and rubber provided between these adhesive parts
By interposing an anti-adhesion sheet having releasability,
Front with the non-bonded part where the two plies are prevented from bonding
It is characterized by forming a bag-like portion .

The invention according to claim 2 is the carcass.
From the tread to the bead through the sidewall
4. It has two plies which overlap inside and outside.
The invention according to claim 1 is a ply that overlaps with the inside and outside, and a ply for sealing.
And a rubber sheet between the
The ply is adhered by interposing a sheet
It is characterized by forming a bag-shaped portion.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a pneumatic tire and a manufacturing method thereof according to the present invention will be described below with reference to the drawings, taking a tire for a motorcycle as an example of a pneumatic tire. FIG. 1 illustrates a motorcycle tire (hereinafter, simply referred to as “tire”) 1. A toroidal carcass extending from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4 is illustrated. And a puncture-preventing sealant 9 extending in the tire circumferential direction is provided inside the tread portion 2, and the sealant 9 is reinforced by a cord inside the tire radial direction of the sealant 9. It has one or more plies 7 for sealing which form a bag-shaped part B for accommodating 9.

The carcass 6 has a radial or semi-radial structure in which carcass cords made of organic fiber cords such as nylon, rayon and polyester are arranged at an angle of 70 to 90 degrees with respect to the circumferential direction, or a carcass of 35 to 70 degrees. One or more carcass plies with an angled bias structure are used. In the present embodiment, the carcass 6 includes two plies 7 which are overlapped inside and outside with the sealing ply 7 being positioned from the tread portion 2 through the sidewall portion 3 to the bead portion 4 and inside the tire radial direction. Including the plies 7 and 6A, and the outer ply 6B on the outside, a total of 3
The thing formed by the sheet of plies is illustrated.

In this example, the encapsulating ply 7 is illustrated as terminating from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. An inner liner rubber i is provided on the inner surface of the sealing ply 7. As the inner liner rubber i, butyl rubber, which has excellent gas impermeability such as butyl rubber, halogenated butyl rubber, and brominated butyl rubber, can be used. For example, a substantially uniform thickness of about 0.5 to 2.0 mm can be used. In addition to the above, the inner surface of the sealing ply 7 can be covered over almost the entire area to prevent air leakage in the tire inner cavity.

The other plies constituting the carcass 6, that is, the plies 6A and 6B, are directed from the tread portion 2 through the sidewall portion 3 to the bead portion 4 around the bead core 5 from the inner side to the outer side in the tire axial direction. The one that is folded back and terminated is illustrated. A bead apex rubber 8 having a triangular cross-section that extends radially outward from the bead core 5 is arranged in the bead portion 4.

The tire 1 of this example has at least one ply 7 for sealing, which is reinforced by a cord, inside the bag-shaped portion B in the radial direction of the tire. It is possible to reduce the difference in rigidity between the outside of the direction (plies 6A, 6B) compared to the conventional case. As a result, the ply 7 for sealing, which is the inner side of the bag-shaped portion B, is not undulated due to an excessive rigidity difference, and the bag-shaped portion B can be formed with high accuracy, and the seal for puncture prevention is formed. It is useful for producing tires filled with the agent 9 with high quality and with good yield and efficiency.

Further, in this embodiment, the sealing ply 7 and the outer ply 6A are integrally provided, for example, an adhesive portion 11 which is adhered by vulcanization, and between the adhesive portion 11 and in the tread portion 2. In addition, the bag-shaped portion B is formed by the non-adhesive portion 12 in which the two plies 7 and 6A are prevented from adhering to each other by interposing the anti-adhesion sheet 10 having the rubber releasability. .

In this case, when forming the bag-like portion B, the ply 7 for sealing the deposition-inhibitory sheet 10 having a constant width and a constant thickness.
Is sufficient to intervene between the ply 6A and the ply 6A, workability in manufacturing can be improved, and the width of the bag-shaped portion B, and consequently the volume of the bag-shaped portion B, can be managed with high accuracy. homogenized and thickness of the sixth layer useful elevational one also to improve the puncture sealing performance.

It is particularly preferable that the deposition-preventing sheet 10 has an elongation property capable of being expanded and deformed together with the surrounding plies during, for example, green tire molding and vulcanization molding. For that purpose, although it is not particularly limited, for example, one having an elongation of 20% or more for a load of 400 g per 8 mm of sheet width is particularly preferable.

As such an anti-adhesion sheet 10, for example, polyfluoroethylene resin which is Teflon (trademark of DuPont) is preferable, and its thickness is 0.05 mm to 0.1 mm.
By setting the thickness to about 5 mm, for example, about 0.1 mm, necessary and sufficient elongation performance can be obtained. Further, for the deposition-inhibitory sheet 10, instead of such a polyfluoroethylene resin, for example, a nylon film or the like can be used as a cheaper material. As this nylon film, for example, one mainly made of nylon 6 (trade name "Rayfan N
“O”, manufactured by Toray Synthetic Film Co., Ltd.) is particularly preferable from the viewpoint of elongation performance and rubber releasability. Table 1 shows the physical properties of such a nylon film.

[0018]

[Table 1]

As a result of various experiments conducted by the inventors, when such a nylon film is used as the anti-adhesion sheet 10, it shows good anti-adhesion properties and elongation performance even if its thickness is, for example, about 25 μm. Have been confirmed. Further, the deposition-preventive sheet 10 is not limited to these examples,
Needless to say, various materials can be used, such as those obtained by impregnating a rubber release agent with another polymer film such as a polyethylene film, or those subjected to a rubber release surface treatment.

The sealing agent 9 filled in the bag-like portion B is liquid at room temperature (20 ° C.), for example, has a viscosity of 2.0 to 10.0 mPa · s (temperature 20 ° C.). The viscous material described above can be preferably used. Besides this,
Various liquid or gel puncture sealants can be used as long as they can enter the nail hole in the temperature range of −20 ° C. to 60 ° C. and seal the nail hole by its self-sealing action.
In this example, the sealing agent 9 has a width of 80% or more of the inner area Y of the tread and is continuously arranged in the circumferential direction. Here, the “tread inner region Y” means a region on the tire inner surface sandwiched by the normals N and N standing on the tread surface 2S at the tread edge Te.
Thereby, the puncture sealing effect can be exhibited over a wide range.

Although not shown in this example, the tire 1
Can further reinforce the tread portion 2 and the like by a cord layer including a breaker, a belt, and the like arranged outside the carcass 6 in the radial direction and inside the tread portion 2.

FIG. 7 shows another embodiment of the present invention. In this example, the carcass 6 extends from the tread portion 2 to the sidewall portion 3 to a bead portion (not shown) and the sealing ply 7 is positioned on the inner side in the tire radial direction. It is composed of 7, 6A. In the tread portion 2, these plies 6A,
7 between the rubber sheets 14a and 14b,
By interposing the adhesion-preventing sheet 10 between the rubber sheets 14a and 14b, the two plies 7, 6A
In this example, the bag-shaped portion B is formed by preventing the above-mentioned adhesion.

In the above two embodiments, the ply 7 for sealing forms the ply of the carcass 6 extending from the tread portion 2 to the sidewall portion 3 to the bead portion 4. For example, it may be terminated at the inner region Y of the tread and disposed only on the inner side in the radial direction of the sealant 6. Also, two or more sealing plies 7 can be arranged.

Next, an example of a method of manufacturing such a pneumatic tire 1 will be described. The manufacturing method of the present embodiment includes a perforating step, an attaching step, an adhesion-preventing sheet attaching step, a raw cover body forming step, and an injecting step.

In the perforating step, as schematically shown in FIGS. 2A and 2B, the inner liner rubber i cut into a predetermined width and a predetermined length, the sealing ply 7, or the inner under cutting is cut. The liner rubber i and the sealing ply 7 are provided with an injection hole 15 for injecting the sealing agent 6 after vulcanization to form the inner liner rubber i with a hole and the sealing ply 7. In the present embodiment, the injection hole 15 having a diameter of 2 to 8 mm is formed in the central portion in the width direction of each rubber or ply.

In the attaching step, as schematically shown in FIG. 3, the inner liner rubber i having holes and the sealing ply 7 are sequentially wound and attached on the molding former 20. Further, in the step of attaching the adhesion-preventing sheet, as schematically shown in FIG. 4, the adhesion-preventing sheet 10 is attached to the upper surface of the sealing ply and the position corresponding to the inside area Y of the tread. In this case, the step of applying the release agent can be replaced with a very simple operation of sticking the adhesion-preventing sheet 10 having a constant width and a constant thickness on the sealing rubber sheet 5, and the productivity is remarkably improved. Can be improved.

Further, in the green cover forming step, as schematically shown in FIG. 5, the other plies 6A, 6B and the bead core 5 are placed on the sealing ply 7 to which the adhesion preventing sheet 10 is attached.
Is added to the tire base structural material and is expanded and deformed into a toroidal shape to form the raw cover body 1A. Here, as the tire base structure material, in this example, bead apex rubber 11, tread rubber 2G, side wall rubber 3 are also used.
Including G and the like, for example, the carcass plies 6A and 6B are folded back at both ends prior to expansion and deformation.

In the injection step, the green cover body 1A is vulcanized and then injected from the injection hole 15 as shown in FIG.
It is a step of injecting the sealing agent 9 into the bag-shaped portion B formed by the non-adhesive portion 12 between the ply 7 and the ply 6A for sealing, the adhesion of which is prevented by the adhesion-preventing sheet 10. . In this injection, a prescribed amount of the sealant 9 is injected using a syringe-like injector f to form a layer of the sealant 9 which is swollen to a predetermined thickness as shown in FIG. In this example, the injection hole 15 after injection is appropriately sealed with an unvulcanized or already vulcanized rubber sheet coated with an adhesive.

As described above, in the method for manufacturing a pneumatic tire of this example, since the deposition-preventing sheet 10 is provided on the sealing ply 7 instead of applying the release agent, the work efficiency is excellent, and the bag is excellent. It is possible to manage the width of the shaped portion B and the like with high accuracy. As a result, the adhesive strength of the bag-shaped portion B can be increased and stabilized, and the width of the non-adhesive portion 12, that is, the volume of the bag-shaped portion B into which the sealing agent 9 is injected is also uniform.
It is possible to obtain a pneumatic tire in which the layer of the sealing agent 9 has a uniform thickness.

[0030]

EXAMPLES Tire size 3.0, which forms the basic structure of FIG.
Various 0-10 motorcycle tires were made by various trials by the above-described manufacturing method while changing the number of sealing plies and the like. Then, the inner surface of the tire after vulcanization was closely inspected, and the finished state such as waviness was examined. Also, in order to check the puncture sealing ability of the tire, after assembling the test tire on the rim and filling the internal pressure,
Stick a nail from the surface side of the tread and make about 10
It was investigated whether or not it was possible to run for 00 km, and the maximum nail hole diameter capable of puncture sealing was investigated. In the examples, the total number of carcass plies was three, including the sealing plies. The test results are shown in Table 2.

[0031]

[Table 2]

As shown in Table 2, the tires of the examples had a better finish on the inner surface of the tire than the conventional examples, almost no waviness, and good puncture sealing performance. was gotten.

[0033]

As described above, according to the present invention, the inner side of the bag-shaped portion in the tire radial direction is preferably provided by providing the cord-reinforced sealing ply on the inner side of the tire radial direction of the bag-shaped portion. Therefore, the difference in rigidity between the bag-shaped portion and the outer side in the tire radial direction can be made smaller than in the conventional case. As a result, the ply for sealing, which forms the inner side of the bag-shaped portion, does not undulate due to an excessive rigidity difference even after vulcanization molding, so that the bag-shaped portion with high accuracy can be formed and puncture prevention can be performed. It is useful for producing a tire filled with a sealant with high quality and with high yield and efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a pneumatic tire of the present invention.

2A and 2B are perspective views illustrating a drilling process.

FIG. 3 is a schematic cross-sectional view showing an attaching step.

FIG. 4 is a schematic plan view illustrating a step of attaching an anti-adhesion sheet.

FIG. 5 is a schematic cross-sectional view illustrating a raw cover body forming step.

FIG. 6 is a schematic diagram illustrating an injection step.

FIG. 7 is a partial cross-sectional view showing another embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating a conventional pneumatic tire.

FIG. 9 is a partial cross-sectional view along the tire circumferential direction for explaining corrugation of the sealing rubber sheet.

[Explanation of symbols]

1 tire 2 tread section 3 Side wall part 4 bead part 5 bead core 6 carcass 6A, 6B ply 7 Ply for sealing 9 Sealant 10 Anti-adhesion sheet

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Claims (3)

(57) [Claims] 1. An air having a toroidal carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion and having a puncture-preventing sealant extending in the tire circumferential direction inside the tread portion. A filled tire, wherein the carcass passes from the tread portion to the sidewall portion.
The ply leading to the bead and the inner side of the tire in the radial direction.
Located to form a bag-like portion for containing the sealant and
And the ply for sealing at least one reinforced by the code
And the sealing ply and the outer ply are integrally formed.
Adhesive parts to be adhered and rubber provided between these adhesive parts
By interposing an anti-adhesion sheet having releasability,
Front with the non-bonded part where the two plies are prevented from bonding
A pneumatic tire having a bag-like portion . 2. The carcass includes a side track from a tread portion.
Two pieces of plastic that overlap the inside and outside of the bead part through the roll part
The pneumatic filter according to claim 1, characterized in that
No 3. A ply that overlaps the inside and outside, and a ply for sealing
A rubber sheet is placed between the
The ply is adhered to the bag by interposing a sheet.
3. The method according to claim 1 or 2, characterized in that the shaped portion is formed.
Pneumatic tires.