JP2011255563A - Method for manufacturing retreaded tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing retreaded tire, capable of preventing the protrusion of cushion rubber at the time of vulcanization in manufacturing a retreaded tire using a precured tread.SOLUTION: A vulcanized precured tread 2 is wound around the crown part of a base tire 1 through unvulcanized cushion rubber 3 and a sealing member 5 covering a jointing part 4 from the surface side of a tread is arranged to the jointing end part thereof to vulcanize and bond the precured tread 2 and the base tire 1 to thereby manufacture the retreaded tire. In this retreaded tire manufacturing method, the sealing member 5 to be used has the unevenness corresponding to the surface groove shape of the precured tread 2 in the jointing part 4 and the width covering the cushion rubber 3 at least in the jointing part 4 in the peripheral direction of the tire and both ends in the width direction of the tire at the time of arrangement are positioned on the inside in the width direction of the tire from the interface of the precured tread 2 and the cushion rubber 3.

Description

  The present invention relates to a method for producing a retread tire (hereinafter, also simply referred to as “tire” and “manufacturing method”), and more particularly, to a method for producing a retread tire using a vulcanized precured tread.

  Conventionally, retreaded tires (retread tires) are widely known as recycled tires. The retread tire is a tire obtained by removing a tread or a tread and a part of a belt layer from a used tire, and a tread portion is replaced with a new tread.

  There are two methods for manufacturing a retread tire: a method in which an unvulcanized tread rubber is bonded to a base tire and vulcanized in a mold, and a tread rubber is patterned in a long mold and vulcanized and precured. There is a method in which a tread is formed and this precure tread is vulcanized and bonded to a base tire. Of these, in the latter method using the precure tread, first, the precure tread is wound around the base tire via the cushion rubber, and the end surfaces of the precure tread are bonded to each other, and then the end surfaces are joined together. A technique is used in which a raw tire is covered with an envelope, put into a vulcanizing can, and vulcanized.

  As an improvement technique related to the precure tread, for example, Patent Document 1 discloses that a precure tread disposed around a base tire is applied to the base tire through a cushion rubber in a reduced-pressure atmosphere in an envelope surrounding them. When performing sulfur bonding, a degassing sheet is disposed between the precure tread and the envelope to cover the entire surface of the precure tread, and the pre-bleed is evacuated through the degas sheet. A tire retreading method using cure tread is disclosed.

JP 2007-331152 A (Claims etc.)

  However, in the conventional method of manufacturing a retread tire using precure tread, the cushion rubber sometimes protrudes during vulcanization at the joint of the precure tread. That is, while heat and pressure are applied during vulcanization, unvulcanized rubber flows, but at the joint portion of the precure tread, as shown in FIGS. 4 (a) and 4 (b), the cushion rubber 11 Since the envelope 12 cannot suppress the flow of the cushion rubber 11, the cushion rubber 11 protrudes 11 </ b> A after vulcanization. Since such protrusion of the cushion rubber deteriorates the tire appearance, it has been required to be eliminated.

  Accordingly, an object of the present invention is to provide a method for producing a retread tire that solves the above-described problems and can prevent the protrusion of cushion rubber during vulcanization when producing a retread tire using a precure tread.

  As a result of intensive studies, the present inventor can solve the above-mentioned problems by arranging a specific-shaped sealing member on the cushion rubber at the joint portion of the precure tread to vulcanize the retread tire. As a result, the present invention has been completed.

That is, according to the present invention, a vulcanized precured tread is wound around a crown portion of a base tire via an unvulcanized cushion rubber, and the joint portion is covered from the tread surface side to the joint end portion of the precured tread. In the manufacturing method of the retread tire which arranges the sealing member and vulcanizes and bonds the precure tread and the base tire,
The sealing member has irregularities corresponding to the groove shape on the surface of the precure tread in the joint portion, and has a width that covers at least the cushion rubber in the joint portion in the tire circumferential direction. What uses both the width direction both ends is located inside a tire width direction rather than the interface of this precure tread and cushion rubber, It is characterized by the above-mentioned.

  In the present invention, the sealing member is preferably made of silicone rubber. Moreover, the width | variety in the tire circumferential direction of the said sealing member is 5 mm-10 mm suitably centering | focusing on the said junction part.

  According to the present invention, with the above-described configuration, when the retread tire using the precure tread is vulcanized, the flow of the cushion rubber can be suppressed by the sealing member, and the protrusion of the cushion rubber can be prevented. Thus, it has become possible to realize a method of manufacturing a retread tire that does not cause deterioration of the appearance of the product tire due to this.

It is explanatory drawing which concerns on the manufacturing method of the retread tire of this invention. It is another explanatory drawing which concerns on the manufacturing method of the retread tire of this invention. It is further explanatory drawing which concerns on the manufacturing method of the retread tire of this invention. It is explanatory drawing which shows the generation | occurrence | production state of protrusion of cushion rubber.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The present invention manufactures a retread tire by winding a vulcanized precured tread around a crown portion of a base tire via an unvulcanized cushion rubber and vulcanizing and bonding the precured tread and the base tire. This is related to the improvement of the method.

  In the present invention, first, as shown in FIG. 1A, the precure tread 2 is placed on the base tire 1 via the cushion rubber 3, and the ends of the precure tread 2 in the tire circumferential direction are placed together. Are joined via an unvulcanized cushion rubber 3. Thereafter, as shown in FIG. 2B, a sealing member 5 that covers the joint 4 from the tread surface side is disposed at the joint end of the precure tread 2. Such a sealing member 5 has irregularities corresponding to the groove shape on the surface of the precure tread 2 in the joint 4 as shown in FIG. 2 which is a cross-sectional view taken along the line AA in FIG. By arranging the sealing member 5 having such irregularities on the cushion rubber 3 in the joint portion 4, as shown in FIG. 3, the sealing member 5 suppresses the flow of the cushion rubber 3 during vulcanization, The cushion rubber 3 can be prevented from protruding outside the groove shape of the precure tread 2. In addition, the code | symbol 6 in a figure shows an envelope.

  The sealing member 5 is required to have at least a width that covers the cushion rubber 3 in the joint portion 4 in the tire circumferential direction, and thereby the effects of the present invention can be obtained. The width in the tire circumferential direction is 5 mm to 10 mm with the joint 4 as the center. If the width of the sealing member 5 in the tire circumferential direction is too wide, heat is not easily transmitted to the inside of the tire during vulcanization, which is not preferable.

  Further, as shown in FIG. 2, the sealing member 5 is required to have both ends 5 e in the tire width direction positioned on the inner side in the tire width direction than the interface between the precure tread 2 and the cushion rubber 3 at the time of arrangement. is there. Here, when the sealing member 5 is disposed such that both ends 5e in the tire width direction are located on the inner side in the tire width direction than the interface between the precure tread 2 and the cushion rubber 3, the sealing member is substantially used. 5 is arranged so as not to reach the interface. Since the interface between the precure tread 2 and the cushion rubber 3 is usually located on the outer side in the tire radial direction from the maximum width position of the tire, the tire width direction both ends 5e of the sealing member 5 are arranged on the tire more than the above interface. By positioning the inner side in the width direction, the sealing member 5 can be prevented from reaching the interface. When the sealing member 5 is disposed to the outer side in the tire width direction than the interface portion between the precure tread 2 and the cushion rubber 3 disposed on the base tire 1, the sealing member 5 is placed inside the tire together with the cushion rubber 3 during vulcanization. As a result of the suction, a recess is formed in the cushion rubber 3 portion of the product tire, and the tire appearance deteriorates.

  Since the sealing member 5 is for preventing the protrusion of the cushion rubber 3 in the joint portion 4 from the outside, the shape in the tire width direction is the tire width direction of the crown portion of the applied retread tire. It shall be along the R shape (see FIG. 2). Further, the circumferential shape of the sealing member 5 also follows the circumferential shape of the applied retread tire (see FIG. 1). The thickness of the portion of the sealing member 5 where the groove is not formed is not particularly limited, but from the viewpoint of handling and strength as a member and from the viewpoint of not hindering heat transfer during vulcanization. For example, 2 mm to 3 mm.

  As the material of the sealing member 5, it is preferable to use silicone rubber, which is a material that does not deform or break even at 120 ° C. during vulcanization of the retread tire. Since silicone rubber is a flexible material, if the sealing member 5 made of silicone rubber is used, the groove shape of the precure tread 2 can be easily followed and the joint 4 of the precure tread 2 has a slight pattern shift. Even in such a case, it is possible to press the cushion rubber 3 of the joint portion 4 without a gap by the deformation of the sealing member 5. Further, by using the sealing member 5 made of silicone rubber, the sealing member 5 can be prevented from adhering to the cushion rubber 3. The sealing member 5 needs to be a member harder than the unvulcanized cushion rubber 3, but is a member softer than the precure tread 2. Specifically, for example, silicone rubber having a viscosity measured by a rotational viscometer of 60 degrees to 70 degrees is used.

  Since the sealing member 5 according to the present invention can effectively prevent the cushion rubber from protruding by using one member for each tire, it is easy to mount the retread tire at the time of manufacture. It also has the advantage of being. In addition, the sealing member 5 according to the present invention can be easily manufactured by molding based on the groove shape of the precure tread 2.

  In the manufacturing method of the retread tire of the present invention, only the point that vulcanization is performed using the sealing member 5 while suppressing the cushion rubber 3 in the joint portion 4 is important. It can be carried out according to the law and is not particularly limited. That is, after the sealing member 5 is disposed, the tire is covered with an envelope in the same manner as in the past, and is put into a vulcanizing can, and vulcanized according to a conventional method to obtain a retread tire with no protrusion of cushion rubber. be able to.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Example>
A used tire having a tire size of 11R22.5 was buffed to obtain a base tire. A precure tread was placed on the crown portion of the obtained base tire via an unvulcanized cushion rubber, and the tire circumferential ends were joined together via an unvulcanized cushion rubber. A sealing member that has irregularities corresponding to the groove shape on the surface of the precure tread in the joint at the joint end of the precure tread and covers the joint from the tread surface side is a cushion rubber in the joint in the tire circumferential direction. It was arranged so as to cover. The thickness of the sealing member in which the groove is not formed is 1 mm, and both ends in the tire width direction are located on the inner side in the tire width direction than the interface between the precure tread and the cushion rubber at the time of arrangement. did. Moreover, this sealing member was produced by molding using silicone rubber (manufactured by Momentive Co., Ltd., main agent: curing agent = 10: 1).

  The tire on which the sealing member was disposed was covered with an envelope and placed in a vulcanization can and vulcanized according to a conventional method to obtain a retread tire of an example. In the obtained retread tire, no protrusion of the cushion rubber was observed at the groove bottom portion of the joint portion of the precure tread.

1 tire 2 precure tread 3 cushion rubber 4 joint 5 sealing member 5e tire width direction both ends 11 of the sealing member 11 cushion rubber 11A protrusion of cushion rubber 6, 12 envelope

Claims (3)

A vulcanized precured tread is wound around the crown portion of the base tire via an unvulcanized cushion rubber, and a sealing member that covers the joint from the tread surface side is disposed at the joint end of the precured tread. In the method of manufacturing a retread tire for vulcanizing and bonding the precure tread and the base tire,
The sealing member has irregularities corresponding to the groove shape on the surface of the precure tread in the joint portion, and has a width that covers at least the cushion rubber in the joint portion in the tire circumferential direction. A method for producing a retread tire using a tire having both ends in the width direction positioned on the inner side in the tire width direction than the interface between the precure tread and the cushion rubber   The method for manufacturing a retread tire according to claim 1, wherein the sealing member is made of silicone rubber.   The method for manufacturing a retread tire according to claim 1 or 2, wherein a width of the sealing member in a tire circumferential direction is 5 mm to 10 mm with the joint portion as a center.

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