JP2004322811A - Pneumatic tire and method of manufacturing the same - Google Patents

Abstract

An object of the present invention is to provide a pneumatic tire and a method of manufacturing the pneumatic tire which exhibit an excellent sealing effect by eliminating bubbles formed in an adhesive sealant layer as much as possible.
A pneumatic tire in which an adhesive sealant layer (8) obtained by decomposing a rubber component with a peroxide is disposed inside an inner liner layer (7) in a tread portion (1), and the adhesive sealant layer (8) is covered with a cover rubber layer (9). The twisted yarn 10 for releasing gas generated in the adhesive sealant layer 8 is disposed between the inner liner layer 7 and the cover rubber layer 9 so that at least one end extends from the edge 9a of the cover rubber layer 9. . Both ends in the tire circumferential direction of the sheet material 13 of the rubber composition to be modified into the adhesive sealant layer 8 are cut into inclined surfaces 13a inclined with respect to the thickness direction, and the sheet material 13 is formed into an annular shape through these inclined surfaces 13a. The adhesive sealant layer 8 is formed by joining.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire having a puncture preventing function and a method for manufacturing the same, and more particularly, to a pneumatic tire in which an adhesive sealant layer for preventing puncture formed by decomposing a rubber component by peroxide is disposed inside a tread portion. And its manufacturing method.
[0002]
[Prior art]
With the development of highways, a number of pneumatic tires have been proposed to avoid a sudden decrease in air pressure due to puncture in order to ensure the safety of the vehicle when the tire steps on a nail or the like while driving. I have.
[0003]
As such a pneumatic tire, an adhesive sealant layer is previously formed on the inner surface of the tire, and when the nail or the like reaches the inside of the tire, a sealant substance adheres to the nail or the like to exhibit a sealing effect. There is. Among them, utilizing the property that polyisobutylene rubber is decomposed by peroxide, a pneumatic tire in which a rubber composition containing polyisobutylene rubber, an inorganic filler and peroxide is modified into a sealant has been proposed. (For example, see Patent Document 1). In this case, the rubber composition that is modified into an adhesive sealant layer has the advantage that it can be handled as a sheet material during tire molding in the same manner as other tire constituent members, and exhibits adhesiveness due to thermal decomposition during tire vulcanization. become.
[0004]
However, when the rubber component is decomposed by the peroxide as described above, a gas may be generated in the adhesive sealant layer. And since the adhesive sealant layer is covered with the cover rubber layer, when gas is generated in the adhesive sealant layer, bubbles are formed between the inner liner layer and the cover rubber layer, and a sufficient sealing effect cannot be obtained. There's a problem. Moreover, when the temperature of the tire increases during running, the bubbles expand and the cover rubber layer ruptures, so that the sealing effect is greatly reduced and the appearance is poor. Further, when a sheet material of a rubber composition that is modified into an adhesive sealant layer is spliced in a tire molding process, air bubbles due to air accumulation are also easily formed in the splice portion, and it is desired to eliminate such air bubbles as much as possible. I have.
[0005]
[Patent Document 1]
JP-A-53-55802 [0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire and a method of manufacturing the pneumatic tire capable of exhibiting an excellent sealing effect by eliminating bubbles formed in an adhesive sealant layer as much as possible.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the pneumatic tire of the present invention has an adhesive sealant layer formed by decomposing a rubber component by peroxide, inside the inner liner layer in the tread portion, and the adhesive sealant layer is formed by a cover rubber layer. In the pneumatic tire covered with, a twisted yarn for releasing gas generated in the adhesive sealant layer extends at least one end from the edge of the cover rubber layer between the inner liner layer and the cover rubber layer. It is characterized in that it is arranged so that
[0008]
In order to achieve the above object, the method for manufacturing a pneumatic tire according to the present invention includes disposing a pressure-sensitive adhesive sealant layer formed by decomposing a rubber component with a peroxide, inside the inner liner layer in the tread portion, In a method of manufacturing a pneumatic tire in which a layer is covered with a cover rubber layer, between the inner liner layer and the cover rubber layer, a sheet material of a rubber composition to be modified into the adhesive sealant layer, at least one end of which is Forming a green tire in which twisted yarns extending from the edge of the cover rubber layer are arranged, and modifying the rubber composition of the sheet material into a gel-like sealant substance during vulcanization of the green tire to form the adhesive sealant layer. While forming, gas generated in the adhesive sealant layer through the twisted yarn is released. .
[0009]
In providing the adhesive sealant layer formed by decomposing the rubber component with the peroxide as described above, by adding a twisted yarn for releasing gas generated at the time of vulcanization modification, bubbles formed in the adhesive sealant layer can be reduced as much as possible. And an excellent sealing effect can be exhibited.
[0010]
On the other hand, another pneumatic tire of the present invention for achieving the above object has an adhesive sealant layer formed by decomposing a rubber component by peroxide, inside an inner liner layer in a tread portion, and the adhesive sealant layer In a pneumatic tire covered with a cover rubber layer, both ends in the tire circumferential direction of a sheet material of a rubber composition to be modified into the adhesive sealant layer are cut into inclined surfaces inclined with respect to a thickness direction, respectively. Wherein the adhesive sealant layer is formed by joining the sheet material in an annular shape via a.
[0011]
Further, another method of manufacturing a pneumatic tire according to the present invention for achieving the above object includes disposing a pressure-sensitive adhesive sealant layer obtained by decomposing a rubber component with a peroxide inside an inner liner layer in a tread portion. A method of manufacturing a pneumatic tire in which an adhesive sealant layer is covered with a cover rubber layer, wherein the tire circumferential direction both ends of the sheet material of the rubber composition to be modified into the adhesive sealant layer are inclined with respect to the thickness direction. To form a green tire in which the sheet material is joined annularly through these inclined surfaces, and the rubber composition of the sheet material is modified into a gel-like sealant substance during vulcanization of the green tire. It is characterized by forming an adhesive sealant layer.
[0012]
In providing the adhesive sealant layer formed by decomposing the rubber component by the peroxide in this manner, the inclined surfaces inclined at both ends in the tire circumferential direction of the sheet material of the rubber composition to be modified into the adhesive sealant layer with respect to the thickness direction. And by joining the sheet material annularly through these inclined surfaces, it is possible to prevent air bubbles from being formed in the splice portion of the adhesive sealant layer due to air accumulation and exhibit an excellent sealing effect. .
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. In the respective drawings, the same components are denoted by the same reference numerals, and redundant description will be omitted.
[0014]
FIG. 1 is a meridian sectional view showing a pneumatic tire according to an embodiment of the present invention, wherein 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3, 3, and the end of the carcass layer 4 is turned around the bead core 5 from the inside to the outside of the tire. A belt layer 6 is arranged on the outer peripheral side of the carcass layer 4 in the tread portion 1. Further, an inner liner layer 7 is disposed inside the carcass layer 4. Further, at a position corresponding to the tread portion 1 inside the inner liner layer 7, an adhesive sealant layer 8 is disposed. Inside the adhesive sealant layer 8, a cover rubber layer 9 covering the inner surface of the adhesive sealant layer 8 is provided. Is arranged.
[0015]
The adhesive sealant layer 8 is obtained by heat-treating a rubber composition containing a rubber component decomposed by peroxide and 0.2 to 20 parts by weight of peroxide with respect to 100 parts by weight of the rubber component. . Such a rubber composition exhibits a solid state at the time of molding, and a rubber component is decomposed by heating during vulcanization to become a gel-like sealant substance, and exhibits tackiness in a vulcanized tire state.
[0016]
Examples of the rubber component decomposed by peroxide (hereinafter, referred to as a peroxide decomposable rubber component) include polyisobutylene rubber and butyl rubber (IIR). Butyl rubber is a copolymer of isobutylene and a small amount of isoprene, and usually has an unsaturation of 2.2 mol% or less.
[0017]
Here, if the amount of the peroxide is less than 0.2 parts by weight with respect to 100 parts by weight of the peroxide decomposable rubber component, the rubber component is not sufficiently decomposed and the sealing effect becomes insufficient. If it exceeds 300, the decomposition proceeds excessively and the viscosity decreases, so that the sealant substance may flow due to centrifugal force during high-speed running.
[0018]
As the peroxide, acyl peroxides (for example, benzoyl peroxide, p-chlorobenzoyl peroxide), ketone peroxides (for example, methyl ethyl ketone peroxide), peroxyesters (for example, t-butyl peroxyacetate, t-butylperoxybenzoate, t-butylperoxyphthalate), alkyl peroxides (for example, dicumyl peroxide, di-t-butylperoxybenzoate, 1,3-bis (t-butylperoxyisopropyl) benzene) ), Hydroperoxides (for example, t-butyl hydroperoxide) and the like.
[0019]
The rubber composition for a sealant may contain another rubber component in addition to the peroxide decomposable rubber component. The rubber component is not particularly limited as long as it can be used for a tire, and examples thereof include isoprene rubber, styrene butadiene rubber, butadiene rubber, and natural rubber.
[0020]
Further, to the rubber composition for the sealant, if necessary, a catalyst such as cobalt naphthenate is added to promote decomposition of the rubber component by peroxide, or an inorganic filler such as carbon black or silica is added. Or an adhesive such as polybutene, or a plasticizer such as an aromatic process oil, a naphthene process oil, or a paraffin process oil. However, clay is not preferred because it hinders peroxide decomposition.
[0021]
In the pneumatic tire, between the inner liner layer 7 and the cover rubber layer 9, a twisted yarn 10 having at least one end extending from the edge 9 a of the cover rubber layer 9 in the tire width direction is arranged. The twisted yarn 10 passes through the inside of the adhesive sealant layer 8 as shown in FIG. The material of the twisted yarn 10 is not particularly limited as long as it has a property of releasing gas, and cotton or a synthetic fiber such as nylon, polyester, or aramid is used. Among them, cotton is preferable from the viewpoint of gas permeability. used.
[0022]
FIGS. 3A to 3C are inner views of the tread portion for illustrating the arrangement of the twisted yarn, respectively, and FIG. 3A shows both ends of the twisted yarn 10 extending from the edge 9 a of the cover rubber layer 9. FIG. 3B shows a case where one end of the twisted yarn 10 is extended from the edge 9 a of the cover rubber layer 9, and FIG. 3C shows a case where the twisted yarn 10 is crossed and both ends thereof are covered with the cover rubber layer 9. 3 shows a case where the edge portion 9a extends from the edge portion 9a. In each case, a plurality of twisted yarns 10 are arranged at intervals in the tire circumferential direction T.
[0023]
As illustrated in FIGS. 3A to 3C, the twisted yarn 10 needs to be arranged so that at least one end thereof extends from the edge 9 a of the cover rubber layer 9, but the arrangement is not particularly limited. Absent. In addition, the twisted yarn 10 can be braided and arranged in a net shape if necessary.
[0024]
FIG. 4 is a cross-sectional view of a tire forming step for explaining the method of manufacturing the pneumatic tire. As shown in FIG. 4, first, the cover rubber layer 9 is wound around the outer peripheral side of the forming drum 12, and at least one end extends in the tire width direction from the edge 9 a of the cover rubber layer 9 around the outer peripheral side of the cover rubber layer 9. A sheet material 13 of a rubber composition to be modified into an adhesive sealant layer 8 is wound together with the twisted yarn 10 to be output. Next, other tire components (not shown) including the inner liner layer 7 are sequentially laminated on the outer peripheral side of the forming drum 12. As a result, between the inner liner layer 7 and the cover rubber layer 9, a sheet material 13 of the rubber composition to be modified into the adhesive sealant layer 8 and the twisted yarn 10 having at least one end extending from the edge 9 a of the cover rubber layer 9. To form a green tire. When this green tire is vulcanized in a mold, the rubber component of the sheet material 13 is decomposed by peroxide and changes into a gel-like sealant substance to form the adhesive sealant layer 8. At this time, gas generated inside the adhesive sealant layer 8 is released to the outside of the adhesive sealant layer 8 (inside the tire) via the twisted yarn 10.
[0025]
In providing the adhesive sealant layer 8 formed by decomposing the rubber component by the peroxide as described above, by adding the twisted yarn 10 for releasing gas generated at the time of vulcanization and denaturation, air bubbles formed in the adhesive sealant layer 8 can be reduced. It can be eliminated as much as possible and an excellent sealing effect can be exhibited. In addition, it is possible to prevent the cover rubber layer 9 from being ruptured due to the expansion of the air bubbles due to the rise in the tire temperature during running, and it is possible to more reliably prevent the sealing effect from further deteriorating and the appearance from being poor.
[0026]
Here, the adhesive sealant layer in the conventional pneumatic tire will be described. In a conventional pneumatic tire, as shown in FIG. 5, a gas generated by the decomposition of a rubber component during vulcanization remains as bubbles 11 inside the adhesive sealant layer 8, which is a factor that hinders the sealing effect. Become. Such bubbles 11 are effectively eliminated by the addition of the twisted yarn 10 described above.
[0027]
In the method of manufacturing the pneumatic tire, in the step of winding the sheet material 13 around the outer peripheral side of the forming drum 12 together with the twisted yarn 10 extending in the tire width direction from the edge 9a of the cover rubber layer 9, the outer peripheral side of the cover rubber layer 9 is formed. The twisted yarn 10 and the sheet material 13 may be wound separately, or the twisted yarn 10 and the sheet material 13 may be combined in advance and wound around the outer peripheral side of the cover rubber layer 9.
[0028]
In the method for manufacturing a pneumatic tire, as shown in FIG. 6, an inclined surface inclined with respect to a thickness direction by skive cutting at both ends in a tire circumferential direction of a sheet material 13 of a rubber composition to be modified into an adhesive sealant layer 8. 13a is preferably formed. Then, a green tire in which the sheet material 13 is joined annularly through these inclined surfaces 13a is formed, and the rubber composition of the sheet material 13 is modified into a gel-like sealant substance during vulcanization of the green tire, thereby forming an adhesive sealant. It is preferable to form the layer 8.
[0029]
In providing the pressure-sensitive adhesive sealant layer 8 formed by decomposing the rubber component with the peroxide as described above, the rubber composition sheet material 13 modified into the pressure-sensitive adhesive sealant layer 8 is inclined at both ends in the tire circumferential direction with respect to the thickness direction. By forming the inclined surfaces 13a to be formed and joining the sheet material 13 in an annular shape through these inclined surfaces 13a, it is possible to prevent air bubbles from being formed in the splice portion of the adhesive sealant layer 8 due to air accumulation and to provide an excellent seal. The effect can be exhibited. In addition, it is possible to prevent the cover rubber layer 9 from being ruptured due to the expansion of the air bubbles due to the rise in the tire temperature during running, and it is possible to more reliably prevent the sealing effect from further deteriorating and the appearance from being poor.
[0030]
That is, in the conventional pneumatic tire having a puncture prevention function, in order to form the adhesive sealant layer 8 seamlessly in the step of joining the sheet material 13 in a ring shape, as shown in FIG. Since both longitudinal ends of the 13 are overlapped and joined, a void 14 is generally formed in the splice. Then, the voids 14 remain as bubbles in the adhesive sealant layer 8 in the tire after vulcanization, which is a factor that hinders the sealing effect. Such air bubbles are effectively eliminated by forming inclined surfaces 13a at both ends in the tire circumferential direction of the sheet material 13 and joining the sheet material 13 annularly through these inclined surfaces 13a.
[0031]
Further, when the sheet material 13 is joined in a ring shape through the inclined surface 13a, the volume of the adhesive sealant layer 8 becomes uniform on the circumference, so that the mass balance of the tire is improved, and the nail is nailed to any part in the tire circumferential direction. This provides an effect that a good sealing effect can be obtained even if the object is pierced.
[0032]
The angle α of the inclined surface 13a with respect to the longitudinal direction (tire circumferential direction) of the sheet material 13 is preferably set to 20 ° to 45 ° in consideration of workability at the time of cutting, adhesive strength, and the like. If the inclination angle α is less than 20 °, the workability at the time of cutting decreases, and if it exceeds 45 °, the adhesive strength of the splice portion becomes insufficient.
[0033]
【The invention's effect】
As described above, according to the present invention, in providing an adhesive sealant layer formed by decomposing a rubber component by peroxide, a twisted yarn for releasing gas generated in the adhesive sealant layer, an inner liner layer and a cover rubber layer Since at least one end is arranged so as to extend from the edge of the cover rubber layer, air bubbles formed in the adhesive sealant layer are eliminated as much as possible, and it is possible to exhibit an excellent sealing effect Become.
[0034]
In addition, when providing an adhesive sealant layer formed by decomposing a rubber component with a peroxide, both ends in the tire circumferential direction of a sheet material of a rubber composition to be modified into an adhesive sealant layer are respectively inclined on a slope inclined with respect to a thickness direction. By cutting and joining the sheet material annularly through these inclined surfaces, it is possible to prevent air bubbles from being formed in the splice portion of the adhesive sealant layer due to air accumulation and to exert an excellent sealing effect Become.
[Brief description of the drawings]
FIG. 1 is a meridian half sectional view showing a pneumatic tire according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view showing a portion A in FIG. 1;
FIGS. 3A to 3C are inner views of a tread portion for illustrating the arrangement of twisted yarns, respectively.
FIG. 4 is a cross-sectional view of a tire forming process for explaining a method of manufacturing a pneumatic tire according to the present invention.
FIG. 5 is a sectional view showing an adhesive sealant layer in a conventional pneumatic tire.
FIG. 6 is a cross-sectional view showing a splice structure of a sheet material of the rubber composition for a sealant in the present invention.
FIG. 7 is a cross-sectional view showing a splice structure of a sheet material of a conventional rubber composition for a sealant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Belt layer 7 Inner liner layer 8 Adhesive sealant layer 9 Cover rubber layer 9a Edge part 10 Twist thread 13 Sheet material 13a Inclined surface α Incline angle

Claims (4)

On the inner side of the inner liner layer in the tread portion, an adhesive sealant layer formed by decomposing a rubber component by peroxide is arranged, and in a pneumatic tire in which the adhesive sealant layer is covered with a cover rubber layer,
A pneumatic tire in which a twist yarn for releasing gas generated in the adhesive sealant layer is arranged between the inner liner layer and the cover rubber layer so that at least one end extends from an edge of the cover rubber layer. . Inside the inner liner layer in the tread portion, an adhesive sealant layer formed by decomposing a rubber component by peroxide is disposed, and in a method for manufacturing a pneumatic tire in which the adhesive sealant layer is covered with a cover rubber layer,
Between the inner liner layer and the cover rubber layer, a sheet material of a rubber composition that is modified into the adhesive sealant layer, and a green tire in which at least one end is provided with a twisted yarn extending from an edge of the cover rubber layer. A gas generated in the pressure-sensitive adhesive sealant layer through the twisted yarn while molding and modifying the rubber composition of the sheet material into a gel-like sealant substance during vulcanization of the green tire to form the pressure-sensitive adhesive sealant layer A method for manufacturing a pneumatic tire in which a tire is pulled out. On the inner side of the inner liner layer in the tread portion, an adhesive sealant layer formed by decomposing a rubber component by peroxide is arranged, and in a pneumatic tire in which the adhesive sealant layer is covered with a cover rubber layer,
Cutting both ends in the tire circumferential direction of the sheet material of the rubber composition to be modified into the pressure-sensitive adhesive sealant layer into inclined surfaces inclined with respect to the thickness direction, and joining the sheet material annularly through these inclined surfaces. A pneumatic tire having the adhesive sealant layer formed thereon. Inside the inner liner layer in the tread portion, an adhesive sealant layer formed by decomposing a rubber component by peroxide is disposed, and in a method for manufacturing a pneumatic tire in which the adhesive sealant layer is covered with a cover rubber layer,
A green sheet obtained by cutting both ends in the tire circumferential direction of a sheet material of a rubber composition to be modified into the adhesive sealant layer into inclined surfaces inclined with respect to a thickness direction, and joining the sheet material in an annular shape through these inclined surfaces. A method for manufacturing a pneumatic tire, wherein a tire is formed and the rubber composition of the sheet material is modified into a gel-like sealant substance during vulcanization of the green tire to form the adhesive sealant layer.

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