JP2000142018A - Pneumatic tire and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate a manufacture of a pneumatic tire provided with a puncture-preventing sealing agent. SOLUTION: In a tread portion 2, a sealing rubber sheet 5 for sealing a sealing agent 6 for preventing a puncture between a tire inner space surface (i) and a tread inner space surface 2i facing thereto is circumferentially extended and is adhered to the tire inner space face (i). The sealing rubber sheet 5 is provided with an adhesion portion 5a in which both tire axial side edges are integrally adhered to an inner rubber 12 disposed along an inner space surface (i) of the tire; and a non-adhesion portion 5b capable of forming a bag-like portion for sealing the sealing agent between a plurality of adhesion-preventing sheets 13A, 13B provided between the adhesion portions 5a, 5a and superposed at the inside and the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubeless type pneumatic tire and a method of manufacturing a pneumatic tire capable of suppressing air leakage from a puncture in a tread portion caused by stepping on a nail or the like.

[0002]

2. Description of the Related Art As one means for preventing the occurrence of air leakage from a punctured part due to a stepping on a nail or the like, for example, as disclosed in JP-A-8-323875, a tire is disclosed. A bag-like portion is formed between the inner liner rubber facing the inner cavity and the sealing rubber sheet attached to the outside thereof, and after vulcanization molding of the tire, a puncture sealant is injected into the bag-like portion using a syringe or the like. Injections have been suggested.

[0003] When the sealing rubber sheet and the inner liner rubber are overlapped with each other in the process of forming a green tire, the bag-like portion is formed of powder such as talc or the like while leaving both side portions on the inner surface of the sealing rubber sheet. A liquid release agent is applied, and both sides of the sealing rubber sheet and the inner liner rubber are vulcanized and bonded at the time of vulcanization molding, so that only the application portion of the release agent is formed as a separated bag-like portion. (Publication

[0004].

[0005] However, in the case of forming the bag-like portion by applying such a release agent, the release agent tends to be excessively applied during the application operation. As a result, it is difficult to stably form a bag-shaped portion having a required strength, for example, the bonding margin of the sealing rubber sheet itself becomes too small, resulting in poor bonding or insufficient bonding strength. If the release agent scatters to other parts of the tire during such an application operation, the tire may be damaged at an early stage. Furthermore, in the coating operation, since the coating thickness varies, sometimes a portion that does not peel off from the inner liner rubber may be partially formed in the bag-shaped portion, and the filling of the puncture sealant becomes uneven. There's a problem.

Accordingly, the present invention is to easily and stably form a bag-shaped portion (non-adhesive portion) having a sufficient adhesive strength,
Moreover, it is an object of the present invention to provide a pneumatic tire that can be manufactured at a low cost and a pneumatic tire capable of efficiently producing a tire filled with a sealant with high quality with good yield.

[0007]

In order to achieve the above object, according to the present invention, there is provided a tire for preventing puncture between a tread portion and a tread inner surface facing a tire inner surface. A sealing rubber sheet for sealing the sealant is extended and attached in the circumferential direction of the tire cavity surface, and the sealing rubber sheet has both side edges in the tire axial direction on the tire cavity surface. An adhesive portion that is integrally bonded to the inner rubber disposed along the inner rubber, and a plurality of adhesion-preventing sheet bodies provided between the adhesion portions and overlapping inside and outside are provided, so that the seal is provided between the adhesion-preventing sheets. A pneumatic tire characterized by comprising a non-adhesive portion capable of forming a bag-like portion for sealing an agent.

According to a second aspect of the present invention, there is provided the pneumatic tire according to the first aspect, wherein the adhesion-preventing sheet is formed of a stretchable polymer film.

According to a third aspect of the present invention, there is provided a method of manufacturing a pneumatic tire in which a sealant for preventing puncture is sealed with a sealing rubber sheet extending in a circumferential direction on the inner surface of the tire. Attachment step of sticking a rubber stopper sheet on a molding former, and attaching an adhesion prevention sheet narrower than the sealing rubber sheet at a position equidistant from the upper surface and both side edges of the sealing rubber sheet. A bonding sheet bonding step of aligning both side edges of the sheet and laminating and bonding two or more of the bonding sheets inside and outside to form a sealing rubber sheet with the bonding sheet; On the upper surface, a raw cover body forming step of forming a raw cover body by positioning a tread lumen surface to be a tire lumen surface of a tread portion, after vulcanizing the raw cover body, adhesion between the adhesion-preventing sheets is performed. Prevented tire lumen surface and sealing rubber A non-adhesive portion between the sealing rubber sheet and a perforation step of forming an injection hole for injecting a sealant into the sealing rubber sheet, and an injection step of injecting a sealant from the injection hole. I have.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pneumatic tire and a method of manufacturing the same according to the present invention will be described below with reference to the drawings, taking a motorcycle tire as an example of a pneumatic tire. FIG. 1 illustrates a motorcycle tire 1 (hereinafter referred to as a tire 1). The tire 1 has a bead portion 4 at each inner end of a sidewall portion 3 extending radially inward from both ends of a tread portion 2. And the tread portion 2 faces the tire lumen surface i.
A sealing rubber sheet 5 for sealing a sealant 6 for preventing puncture is provided between the sealing rubber sheet 5 and the peripheral surface i of the tire so as to extend in the circumferential direction.

The tire 1 is reinforced by a cord layer including a carcass 8 bridged between the bead portions 4, 4 and a breaker 9 disposed radially outside the carcass 8 and inside the tread portion 2. The required tire strength and rigidity are provided. The bead portion 4 is provided with a bead apex rubber 11 having a triangular cross section extending radially outward from the bead core 10 to increase the rigidity of the bead portion.

The carcass 8 may be a radial or semi-radial structure in which carcass cords are arranged at an angle of 70 to 90 degrees with respect to the circumferential direction, or a bias structure in which carcass cords are arranged at an angle of 35 degrees or more and less than 70 degrees. The carcass ply described above is used, and in this example, one carcass ply is illustrated in which both ends are folded back around the bead core 10 and locked.

The breaker 9 is formed of one or more breaker plies in which the breaker cords are arranged at an angle of 0 to 70 degrees with respect to the circumferential direction, and the number of the plies is set as required. In addition, the breaker 9 can be omitted depending on the tire.

An inner liner rubber 12 which is hardly permeable to gas in this embodiment is attached to the inner surface of the carcass 8 so that the inner liner rubber 12 is attached to the inner surface i of the tire.
Are arranged along with the inner rubber G. The inner liner rubber 12 is made of, for example, butyl rubber, halogenated butyl rubber, brominated butyl rubber, or the like, has a substantially uniform thickness of, for example, about 0.5 to 2.0 mm, and covers almost the entire inner surface of the carcass 8. Are arranged as described above. In some cases, the topping rubber topping the carcass ply forms the inner rubber G disposed along the tire inner surface i.

In this embodiment, the inner liner rubber 1
2 shows the inner surface on which the sealing rubber sheet 5 is provided. In this example, the sealing rubber sheet 5 is exemplified by a band-shaped rubber sheet having a width of 80% or more of the area Y of the tread lumen surface 2i and extending continuously in the circumferential direction. The “region Y of the tread lumen surface” is a region on the tire lumen surface which is sandwiched between normals N, N standing on the tread surface 2S at the tread edge Te.

At both side edges of the sealing rubber sheet 5, adhesive portions 5a, 5a, which are, for example, vulcanized and bonded integrally with the inner liner rubber 12 forming the inner rubber G in this example.
a. The width L0 of each of the bonding portions 5a (FIG. 1)
Is preferably set to, for example, 4.0 to 10.0 mm, more preferably 5.0 to 7.0 mm. When the width L0 of the bonding portion 5a is smaller than 4.0 mm, the bonding strength tends to be insufficient, and when the width L0 exceeds 10.0 mm,
The width of the area filled with the sealant 6 is unnecessarily reduced.

The sealing rubber sheet 5 is, for example, 0.5 to
Preferably, the thickness is 2.0 mm. This thickness is 0.
If it is less than 5 mm, the strength is insufficient and the sealing or protection of the sealing agent 6 is insufficient, and the internal pressure filled in the tire is
There is a tendency that it is difficult to uniformly load the sealant 6.
Conversely, if the thickness of the sealing rubber sheet 5 exceeds 2.0 mm, an unnecessary increase in tire weight tends to occur. From such a viewpoint, the thickness of the sealing rubber sheet 5 is 1.0 to 1.5.
mm is particularly preferred.

The sealing rubber sheet 5 has substantially the same butyl rubber, brominated butyl rubber,
Particularly preferred are rubber compositions that can be bonded to the inner rubber G by the heat of vulcanization, such as halogenated butyl rubber, and various rubbers such as a compounded rubber obtained by blending a diene rubber such as styrene / butadiene can be used as appropriate.

The bonding portion 5 of the sealing rubber sheet 5
A plurality of deposition sheets 13A and 13B (which may be simply referred to as “deposition sheet 13” when collectively referred to) are superposed between a and 5a in a radial direction,
A non-adhesive portion 5b that can form a bag-like portion for sealing the sealant 6 is formed between the adhesion-preventing sheets 13A and 13B.

The sealant 6 has a liquid or gel state at normal temperature (20 ° C.) and has a viscosity of 2.0 to 1 for example.
A viscous material having a pressure of 0.0 mPa · s (temperature: 20 ° C.) can be suitably used. In addition, various puncture sealants can be used as long as they can seal nail holes in a temperature range of -20 ° C to 60 ° C.

Further, the adhesion-preventing sheet 13 has, for example, a width substantially equal to the area Y of the tread lumen surface 2i, and in this example, is made to be about 8 to 20 mm narrower than the sealing rubber sheet 5. This shows what is formed of a band. Further, the adhesion-preventing sheet of this example is made of a polymer film that can be stretched in accordance with the expansion and deformation of the tire. For example, a polymer film having an elongation of 20% or more for a load of 400 g per 8 mm of sheet width is particularly preferable.

The anti-adhesion sheet 13 of the present embodiment is, for example, one having no releasability from rubber. Accordingly, the inward facing surface of the inner anti-adhesive sheet 13A is in close contact with the sealing rubber sheet 5, and the outer facing surface of the outer anti-adhesive sheet 13B is in close contact with the inner rubber G. However, the adhesion-preventing sheets 13A and 13B have physical properties such that they do not adhere to each other at least by the heat of vulcanization of the tire. Thus, in the present embodiment, the sealant 6 is filled between the anti-adhesion sheets 13 while adopting an inexpensive polymer film having no releasability from rubber, for example, a polyethylene film. The bag-shaped part can be easily formed, which helps to reduce the cost of the tire.

In addition, as shown in FIG. 3, as a method of stacking the attachment-preventing sheet 13 inside and outside in the tire radial direction, one sheet S is continuously wound two or more times in the circumferential direction, and FIG. As shown, a sheet obtained by superimposing two sheets S1 and S2 may be wound one round with an overlap margin. Also, as shown in FIG. 5, a wide sheet S may be folded at substantially the middle in the width direction to form two layers and wound one or more times. Further, as shown in FIG. 6, both ends of the wide sheet may be wound. May be folded back toward the center in the width direction to overlap the inside and outside. As described above, various methods can be adopted as a method of stacking the adhesion-preventing sheets 13A and 13B.

As the adhesion-preventing sheet 13, an expensive but rubber-releasing film such as Teflon (trademark of DuPont) such as polyfluoroethylene resin can be used. In this case, although not shown, a bag-like portion can be formed not only between the adhesion-preventing sheets, but also between each adhesion-preventing sheet and the rubber, and the sealing agent 6 is multi-layered (for example, 2 to 3).
Layer).

As a result of experiments by the inventors, such a film could be set to a thickness of, for example, about 0.05 mm to 0.15 mm. In addition, a nylon film can be used as a material which is more inexpensive and has rubber releasability than the polyfluoroethylene resin film. As this nylon film, for example, a film mainly made of nylon 6 (trade name “Reifan NO”,
Toray Synthetic Film Co., Ltd.) is particularly preferred. Table 1 shows the physical properties of such a nylon film.

[0026]

[Table 1]

As a result of various experiments by the inventors, when such a nylon film is used as an anti-adhesion sheet, good anti-adhesion properties and elongation performance are exhibited even if its thickness is, for example, about 25 μm. That has been confirmed.

Next, an embodiment of a method for manufacturing the tire 1 will be described. The manufacturing method of the present embodiment includes an attaching step, an adhesion-preventing sheet laminating step, a raw cover body forming step,
An example including a drilling step and an injection step will be exemplified, and will be described below in order.

First, in the mounting step, as shown in FIG. 7A, in this example, the sealing rubber sheet 5 is affixed to the molding former 20 in a position corresponding to the tread inner region Y in a circumferential direction. To wear.

Next, the adhesion-preventing sheet laminating step is performed as shown in FIG.
As shown in (B), the both-side edges of the adhesion-preventing sheet 13 are aligned with the upper surface of the sealing rubber sheet 5 and at a position separated from the both-side edges by a distance equal to the width L0. Moreover, two or more sheets are laminated and adhered inside and outside (in this example, the adhesion-preventing sheets 13A and 13B overlap to form two layers) to form the sealing rubber sheet 5B with the adhesion-preventing sheet.

As described above, in the present invention, the step of conventionally applying the release agent one by one is a very simple step of attaching the anti-adhesion sheet 13 having a constant width and a constant thickness to the sealing rubber sheet 5. Can be replaced with work. Various methods as shown in FIGS. 3 to 6 can be adopted as a method of stacking the deposition-inhibiting sheet 13 inside and outside in the tire radial direction.

In this embodiment, as shown in FIG. 8A, an inner liner rubber 12 serving as a tread inner cavity surface 2i is provided on the upper surface of the sealing rubber sheet 5B provided with the anti-adhesion sheet.
8B, and a tire base structural material such as a carcass 8 and a bead core 10 is added to the inner liner rubber 12 as schematically shown in FIG. A green cover forming step of forming 1A is performed. Here, as the tire base structural material,
In this example, bead apex rubber 11, breaker 9, tread rubber 2G, and side wall rubber 3G are additionally provided, and both ends of carcass 8 are folded back before the expansion.

Next, after vulcanizing the green cover, in this example, the sealing rubber sheet 5 and the inner anti-adhesion sheet 13A are
An example in which a perforation process for forming an injection hole 15 for injecting the sealant 6 is performed is illustrated. For this reason, the injection hole 15 can be formed with higher precision than when the injection hole 15 is formed before vulcanization. In the present example, the injection hole 15 has a diameter of 2 to 2.
A sheet of 8 mm is pierced substantially at the center of the sealing rubber sheet 5 in the width direction, but the number, shape, size, and the like can be arbitrarily determined.

Further, as shown in FIG.
From the injection hole 15, at least the anti-adhesive sheet 13
A, a non-adhesive portion 5b between the inner liner rubber 12 and the sealing rubber sheet 5 where the adhesion is prevented between 13B,
A process of injecting the sealing agent 6 is performed. This injection is performed, for example, by injecting a prescribed amount using a syringe-shaped injector, whereby a layer of the sealant 6 swelling to a predetermined thickness is formed.
In this example, the injection hole 15 and the like after the injection are appropriately sealed with an unvulcanized or vulcanized rubber sheet coated with an adhesive.

As described above, in the method of manufacturing a pneumatic tire according to the present embodiment, a predetermined adhesion-preventing sheet is laminated inside and outside and affixed to the sealing rubber sheet 5 instead of applying a release agent. The efficiency is excellent, and the width L0 of the bonding portion 5a at both ends can be managed with high accuracy. as a result,
The adhesive strength of the bag-like portion can be increased and stabilized, and the non-adhesive portion 5b can be provided between the overlapping adhesion-preventing sheets and at the width thereof.
That is, the bag-shaped portion into which the sealing agent is injected can be easily and reliably formed, the volume thereof does not vary, and the sealing agent 6 can be formed.
A pneumatic tire having a uniform thickness of the puncture prevention layer can be obtained.

Further, it is possible to effectively suppress the peeling failure due to the coating unevenness of the conventional release agent, and it is possible to produce a high quality tire with good yield and efficiency.

Although the present embodiment has been described in detail, for example, the inner rubber G does not need to be the inner liner rubber 12 and may be used as a topping rubber for the carcass ply.
At this time, one bead portion 4 is provided so that the sealing rubber sheet 5 also has a function as the inner liner rubber 12.
To the other bead portion 4 and the present invention can be modified in various modes.

Note that the tire size of the structure shown in FIG.
A motorcycle tire of No. 00-10 was prototyped using the above-described manufacturing method, and trial production was performed according to the specifications shown in FIGS. 3 to 6 as a method of laminating an anti-adhesive sheet. Has been confirmed to be.

[0039]

As described above, in the pneumatic tire according to claim 1 or 2, the puncture-preventing sealant is sealed between the tread portion and the tread cavity surface facing the tire cavity surface. Along with sealing the sealing rubber sheet to be extended in the tire cavity surface and circumferential direction, the sealing rubber sheet is
By attaching a plurality of anti-adhesion sheets overlapping inside and outside, a non-adhesion portion which can form a bag-shaped portion for sealing the sealant can be easily formed between the anti-adhesion sheets, and productivity is improved. .

Further, as the anti-adhesion sheet, for example, an inexpensive polymer film having no releasability from rubber can be used, and a puncture preventing tire can be provided at low cost. Further, it is possible to obtain a highly accurate pneumatic tire in which the volume of the bag-shaped portion into which the sealant is injected is not varied, and the thickness of the sealant layer is made uniform. Furthermore, when a film having a releasability from rubber is used for the anti-adhesion sheet,
The sealant can be formed in multiple layers, and the puncture prevention effect can be further enhanced.

According to the third aspect of the present invention, since an inner and outer anti-adhesion sheet is attached to the sealing rubber sheet instead of applying the release agent, the work efficiency is excellent and the bonding of both ends of the sealing rubber sheet is performed. It is possible to control the width of the portion with high precision, so that the adhesive strength of the bag-shaped portion can be increased and stabilized, and the width of the non-adhered portion, that is, the volume of the bag-shaped portion into which the sealing agent is injected is further increased. A pneumatic tire in which there is no variation and the thickness of the sealant layer is uniform can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a pneumatic tire.

FIG. 2 is an enlarged sectional view of the tread portion.

FIG. 3 is a side view showing an example of the overlap of the adhesion preventing sheets.

FIG. 4 is a side view showing another example of the overlap of the adhesion preventing sheets.

FIG. 5 is a cross-sectional view showing an example of the overlap of the adhesion preventing sheets.

FIG. 6 is a cross-sectional view showing another example of the overlap of the adhesion-preventing sheets.

FIGS. 7A and 7B are schematic views illustrating an attaching step and an adhesion-preventing sheet laminating step.

FIG. 8 (A) and (B) show an inner liner rubber sticking step,
It is a schematic diagram explaining a raw cover body formation process.

FIG. 9 is a schematic diagram illustrating an injection step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tire 1A Raw cover body 5 Sealing rubber sheet 5b Non-adhesive part 6 Sealing agent 8 Carcass 10 Bead core 12 Inner liner rubber 13 Deposition sheet 15 Injection hole 16 Tire base structural material 20 Molding former

Claims (3)

[Claims] 1. A sealing rubber sheet for sealing a puncture-preventing sealant between a tread portion and a tread inner surface facing a tire inner surface and extending in a circumferential direction of the tire inner surface. At the same time, the sealing rubber sheet is provided between the bonding portion and both side edges in the axial direction of the tire integrally bonded to the inner rubber disposed along the inner surface of the tire. And air having a non-adhesive portion capable of forming a bag-like portion for sealing the sealant between the anti-adhesion sheets when a plurality of anti-adhesion sheets overlapping inside and outside are provided. Containing tires. 2. The pneumatic tire according to claim 1, wherein the adhesion-preventing sheet is made of a stretchable polymer film. 3. A method for manufacturing a pneumatic tire in which a sealant for preventing puncture is sealed with a sealing rubber sheet extending in a circumferential direction on a tire cavity surface, wherein the sealing rubber sheet is formed on a molding former. Attachment step of adhering to the sealing rubber sheet, the adhesion sheet having a width smaller than that of the sealing rubber sheet, the upper edge of the sealing rubber sheet and a position equidistant from both side edges, aligning both side edges of the adhesion preventing sheet And attaching and bonding two or more sheets of the adhesion-preventing sheet inside and outside to form a sealing rubber sheet with the adhesion-preventing sheet. A raw cover body forming step of forming a raw cover body by locating a tread lumen surface serving as a lumen surface, and after vulcanizing the raw cover body, a tire lumen surface in which adhesion between the adhesion preventing sheets is prevented. To the non-adhesive part between the A method for manufacturing a pneumatic tire, comprising: a step of forming an injection hole for injecting a sealant in the sealing rubber sheet; and an injection step of injecting a sealant from the injection hole.