JP2012121413A - Run-flat tire and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a run-flat tire with excellent durability, and to provide a method for manufacturing the same.SOLUTION: The run-flat tire includes a polymer thin film that is disposed on the inside in a tire axial direction of an insert and/or a bead and has a film thickness of 0.1-10 mm.

Description

The present invention relates to a run-flat tire and a manufacturing method thereof.

Even if run-flat tires with high-strength inserts (sidewall reinforcement layers) placed inside the sidewalls have been put into practical use and the air pressure has been lost due to puncture (zero internal pressure), the tires Even when subjected to repeated bending, the rubber is less damaged and can travel safely to some extent. As a result, there is no need to always have spare tires, and weight reduction of the entire vehicle can be expected. However, there is a limitation on speed and distance in run flat running during puncture of the run flat tire, and further improvement of the durability of the run flat tire is desired.

As a method of improving the durability of the run-flat tire, there is a method of suppressing deformation by increasing the thickness of the insert and preventing destruction due to the deformation. However, since the weight of the tire increases, it is contrary to the weight reduction that is the original purpose of the run-flat tire.

In addition, increasing the amount of reinforcing filler such as carbon black can increase the hardness of the insert and suppress deformation, but in the processes such as kneading and extruding, the load on the kneading machine increases and vulcanization occurs. Since heat generation increases in the post physical properties, improvement in run flat durability cannot be expected so much.

In addition, there is a method of increasing the amount of vulcanizing agent or vulcanization accelerator, but the elongation of rubber is reduced, the breaking strength is reduced, and a large amount of vulcanizing agent or vulcanization accelerator is present on the surface. Blooming tends to occur, and processability and storage stability tend to decrease.

Patent Document 1 discloses a method for improving the durability of a run-flat tire by blending a coal pitch-based carbon fiber into an insert or a sidewall. However, other methods are also required.

JP 2010-168540 A

An object of the present invention is to solve the above-described problems and provide a run-flat tire having excellent durability and a method for manufacturing the same.

The present invention relates to a run-flat tire having a polymer thin film disposed on the inner side in the tire axial direction of an insert and / or a bead and having a film thickness of 0.1 to 10 mm.

The polymer thin film preferably has a thermal conductivity of 1 to 30 W / m · K.

The polymer thin film preferably contains at least one polymer selected from the group consisting of polythiophene, polyaniline, polypyrrole, and derivatives thereof.

The present invention also includes the step 1 of attaching the polymer-containing solution 1 to the inside of the unvulcanized tire insert and / or the bead in the tire axial direction, and the inside of the unvulcanized tire insert and / or the bead in the tire axial direction. The present invention relates to a method for manufacturing the run-flat tire, which includes a step 2 of attaching a solution 2 containing a metal catalyst to the surface and a step 3 of vulcanizing the unvulcanized tire to form the polymer thin film in this order.

According to the present invention, since the run-flat tire has a specific polymer thin film disposed on the inner side in the tire axial direction of the insert and / or the bead, the heat generated in the insert and / or the bead is wheeled by the polymer thin film. By releasing to the side, excellent durability (run-flat durability) can be obtained. In addition, unlike the conventional method described above, there is no need to change the design of other tire members, so that problems such as an increase in tire weight do not occur.

1 is a cross-sectional view illustrating a part of a run flat tire according to an embodiment of the present invention.

Hereinafter, an example of a preferred embodiment of the run-flat tire of the present invention will be described with reference to the drawings as appropriate.
In FIG. 1, the vertical direction is the tire radial direction, the horizontal direction is the tire axial direction, and the direction perpendicular to the paper surface is the tire circumferential direction. The run flat tire 1 includes a tread portion 2, a sidewall portion 3, a carcass 4, a bead 5, a breaker 6, an insert 7, an inner liner 8, and a polymer thin film 9. The carcass 4 is configured by a carcass ply that is folded around the bead core 5 </ b> A included in the bead 5 from the tread portion 2 through the sidewall portion 3. The bead 5 includes a bead core 5A and a bead apex 5B extending outward from the bead core 5A in the tire radial direction. The breaker 6 is composed of two breaker plies 6A and 6B in which cords are arranged at an angle of 5 to 30 degrees in the tire circumferential direction. The breaker plies 6A and 6B are arranged so that the cords of the breaker plies 6A and 6B intersect each other. Has been. The insert 7 is disposed on the inner side in the tire axial direction of the carcass 4 and has a substantially crescent-shaped cross section. On the inner side in the tire axial direction of the insert 7, an inner liner 8 made of rubber that does not easily transmit air is disposed.

The polymer thin film 9 is disposed inside the bead 5 and the insert 7 in the tire axial direction. Since the heat generated in the bead 5 and the insert 7 is released to the wheel side by the polymer thin film 9, breakage of the bead 5 and the insert 7 can be suppressed, and run-flat durability can be improved. The polymer thin film 9 may be disposed on the inner side in the tire axial direction from the bead 5 and the insert 7, and other members may be disposed between the polymer thin film 9 and the bead 5 and the insert 7 (this book In the embodiment, an inner liner 8 is disposed). Further, the polymer thin film 9 may be disposed on the inner side in the tire axial direction of at least one of the bead 5 and the insert 7, but is disposed on the inner side in the tire axial direction of both the bead 5 and the insert 7 as in the present embodiment. It is preferred that

The film thickness of the polymer thin film 9 is 0.1 mm or more, preferably 0.5 mm or more, more preferably 2 mm or more. If the thickness is less than 0.1 mm, the strength of the polymer thin film 9 is low, and good run-flat durability tends not to be obtained. The film thickness of the polymer thin film 9 is 10 mm or less, preferably 9 mm or less, more preferably 5 mm or less. If it exceeds 10 mm, the polymer thin film 9 cannot be formed uniformly, and there is a tendency that good run-flat durability cannot be obtained.
The film thickness of the polymer thin film 9 can be adjusted by, for example, a method of changing the number of times the solution containing the polymer is applied or the concentration of the polymer in the solution. Can be measured.

The thermal conductivity of the polymer thin film 9 is preferably 1 W / m · K or more, more preferably 4 W / m · K or more, and further preferably 6 W / m · K or more. If it is less than 1 W / m · K, the heat generated from the insert 7 and the bead 8 cannot be sufficiently released, and there is a tendency that good run-flat durability cannot be obtained. The thermal conductivity of the polymer thin film 9 is preferably 30 W / m · K or less, more preferably 15 W / m · K or less, and still more preferably 10 W / m · K or less. If it exceeds 30 W / m · K, the polymer thin film 9 is destroyed at an early stage and good run-flat durability tends not to be obtained.
The thermal conductivity of the polymer thin film 9 can be adjusted by, for example, a method such as changing the type of polymer, and can be measured by the method of an example described later.

The polymer thin film 9 contains at least one polymer selected from the group consisting of polythiophene, polyaniline, polypyrrole, and derivatives thereof from the viewpoint that a desired film thickness and thermal conductivity can be easily obtained. Is preferred. That is, the polymer thin film 9 is preferably prepared using the polymer as a raw material. Examples of the derivative include polyethylene dioxythiophene, polyaniline sulfonic acid, and a copolymer of ethyl 3-methyl-4-pyrrolecarboxylate and butyl 3-methyl-4-pyrrolecarboxylate. As the polymer, polythiophene and derivatives thereof are preferable from the viewpoint that the obtained polymer thin film 9 has good thermal conductivity and strength.

The run-flat tire 1 includes, for example, a step 1 in which a solution 1 containing a polymer is attached to the inner side in the tire axial direction of the insert 7 and / or the bead 5 of the unvulcanized tire, and the insert 7 and / or the unvulcanized tire. More preferably, the manufacturing method includes the step 2 of attaching the solution 2 containing the metal catalyst to the inside of the bead 5 in the tire axial direction and the step 3 of vulcanizing the unvulcanized tire to form the polymer thin film 9 in this order. can get. According to this manufacturing method, the polymer thin film 9 can be favorably bonded to other tire members, and run flat durability can be further improved. In addition, by using a metal catalyst, it is possible to efficiently form a smooth polymer thin film 9 and to allow the polymer thin film 9 to contain a metal derived from a metal catalyst and to obtain good thermal conductivity. .

(Process 1)
In step 1, a solution 1 containing a polymer is adhered to the inside of the uncured tire insert 7 and / or the bead 5 in the tire axial direction. A method for attaching the solution 1 is not particularly limited, and a general method can be used. For example, a method of applying the solution 1 using a brush or the like can be used.

As the solution 1, a solution in which a polymer is dissolved in a solvent can be used. It does not specifically limit as a solvent used for the solution 1, Well-known solvents, such as water, alcohol, toluene, are mentioned. The polymer is a raw material for the polymer thin film 8, and the above-described polythiophene and the like can be preferably used.

(Process 2)
In step 2, a solution 2 containing a metal catalyst is attached to the inside of the uncured tire insert 7 and / or the bead 5 in the tire axial direction. A method for attaching the solution 2 is not particularly limited, and a general method can be used. For example, a method of spraying the solution 2 using a spray or the like can be used.

As the solution 2, a metal catalyst dissolved in a solvent can be used. It does not specifically limit as a solvent used for the solution 2, Well-known solvents, such as water, alcohol, toluene, are mentioned. In addition, examples of the metal catalyst include metal salts such as ferric chloride, ferric nitrate, ferric bromide, cupric chloride, and molybdenum chloride. Among these, ferric chloride is preferable because the effects of the present invention can be obtained satisfactorily.

(Process 3)
In step 3, the polymer thin film 9 is formed by vulcanizing the unvulcanized tire. The vulcanization method is not particularly limited, and those generally used in the tire industry can be used. The vulcanization temperature is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, preferably 200 ° C. or lower, more preferably 180 ° C. or lower. The vulcanization time is preferably 15 minutes or longer, more preferably 20 minutes or longer, preferably 30 minutes or shorter, more preferably 25 minutes or shorter. If the vulcanization temperature and vulcanization time are within the above ranges, the polymer thin film 9 having a desired film thickness can be efficiently formed.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

(material)
Polypyrrole: SSPY (copolymer of ethyl 3-methyl-4-pyrrolecarboxylate and butyl 3-methyl-4-pyrrolecarboxylate) manufactured by Kaken Sangyo Co., Ltd.
Polyaniline-containing solution: Toluene type (T) manufactured by Kaken Sangyo Co., Ltd. (toluene solution having a polyaniline (solid content) content of 6% by mass)
Polythiophene-containing solution: BaytronP HC V4 (polyethylenedioxythiophene (solid content) content 1.2% by weight aqueous solution) manufactured by Kaken Sangyo Co., Ltd.
Ferric chloride: Wako Pure Chemical Industries, Ltd. Toluene: Wako Pure Chemical Industries, Ltd. Ethyl alcohol: Wako Pure Chemical Industries, Ltd.

(Examples 1-2)
After producing an unvulcanized tire including an insert and a bead, a solution (produced by dissolving polypyrrole in toluene) having a polypyrrole content of 10% by mass was applied to the inside of the insert and bead in the tire axial direction with a brush (process) 1). After standing for 3 hours, a solution having a ferric chloride content of 20% by mass (produced by dissolving ferric chloride in ethyl alcohol) was sprayed on the inner side in the tire axial direction of the insert and bead (step 2). ). Thereafter, the unvulcanized tire was press vulcanized at 160 ° C. and 25 kgf for 20 minutes to produce a test run-flat tire (tire size: 195 / 65R15) (step 3). By this press vulcanization, a polymer thin film was formed on the inner side in the tire axial direction of the insert and the bead.

(Examples 3 to 4)
A test run-flat tire was produced in the same manner as in Example 1, except that the solution used in Step 1 was changed to a polyaniline-containing solution.

(Examples 5-6)
A test run flat tire was produced in the same manner as in Example 1 except that the solution used in Step 1 was changed to a polythiophene-containing solution.

(Comparative Example 1)
A test run flat tire was produced in the same manner as in Example 1 except that the polymer thin film was not formed.

(Comparative Examples 2-7)
A test run flat tire was produced by the same method as in any of Examples 1 to 6 except that the thickness of the polymer thin film was changed.

(Film thickness)
The film thickness of the polymer thin film was measured by using an electromagnetic film thickness meter (Positector 6000F series, simple film thickness meter DFT-F manufactured by Defersco) based on ASTM D1400, ISO2360, and ISO2808.

(Thermal conductivity)
The thermal conductivity of the polymer thin film was measured by a laser flash method using LF / TCM-FA8510B manufactured by Rigaku Corporation. In Comparative Example 1, the thermal conductivity of the internal components of the test run-flat tire was measured.

(Run flat durability)
The run flat tire for test was run on a drum at 80 km / h at an air pressure of 0 kPa, the running distance until the tire broke down was measured, and the running distance of each example was indicated by an index by the following formula. It shows that it is excellent in run flat durability (RF durability), so that an index | exponent is large.
(Run-flat durability index) = (travel distance in each example) / (travel distance in Comparative Example 1) × 100

From Tables 1 and 2, the examples having the polymer thin film having a film thickness within a specific range have greatly improved run-flat durability compared to the comparative example.

DESCRIPTION OF SYMBOLS 1 Run flat tire 2 Tread part 3 Side wall part 4 Carcass 5 Bead 5A Bead core 5B Bead apex 6 Breaker 6A Breaker ply 6B Breaker ply 7 Insert 8 Inner liner 9 Polymer thin film

Claims (4)

A polymer thin film disposed on the inner side in the tire axial direction of the insert and / or the bead;
A run-flat tire in which the polymer thin film has a thickness of 0.1 to 10 mm. The run flat tire according to claim 1, wherein the polymer thin film has a thermal conductivity of 1 to 30 W / m · K. The run-flat tire according to claim 1 or 2, wherein the polymer thin film includes at least one polymer selected from the group consisting of polythiophene, polyaniline, polypyrrole, and derivatives thereof. A step 1 of attaching a solution 1 containing a polymer to the inner side in the tire axial direction of an insert and / or a bead of an unvulcanized tire;
A step 2 of attaching a solution 2 containing a metal catalyst to the inside of the unvulcanized tire insert and / or bead in the tire axial direction;
The method for producing a run-flat tire according to any one of claims 1 to 3, further comprising, in this order, step 3 of vulcanizing the unvulcanized tire to form the polymer thin film.

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