JPH09295360A - Vulcanized tread for retreaded tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture retarded tires without the detriment to productivity by positively preventing separation from the casing of a tread. SOLUTION: The vulcanized tread 4 for a retreaded tire is adhered integrally on the foundation tire via a cushion rubber layer 3, and provided with compression distortional release-absorption parts 4C at both its ends, and further it is provided integrally with the same quality of lower heat rubber 5 as the cushion rubber layer 3 at an adhesion area relative to the cushion rubber layer 3 or an adhesion area of an entire surface including the tread both ends.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vulcanized tread for retreaded tires.

[0002]

2. Description of the Related Art A vulcanized tread (referred to as a belt-shaped tread that has been previously vulcanized or semi-vulcanized to form a tread pattern, the same applies hereinafter) is attached to a buffed base tire with an adhesive and a thickness of 1 to 2 mm. A retreaded tire is created by pressure-bonding and vulcanizing with an unvulcanized cushion rubber layer interposed.

When this retreaded tire is mounted on an automobile or the like and is driven, the adhesive layer portion is repeatedly compressed by the rotational movement of the tire to generate dynamic strain, and the resulting heat generation or high heat generation due to repeated compression of the hard tread rubber. Deterioration is accelerated by peeling at the interface of the tire tire and the adhesive rubber layer or between the adhesive rubber layer and the vulcanized tread, especially at the tire shoulders where the movement is vigorous. I have something to do.

As a countermeasure against this, Japanese Unexamined Patent Publication No. 56-53903.
As disclosed in Japanese Unexamined Patent Publication (Kokai), a repetitive compression strain caused by tire rotation is formed by forming concave grooves continuous in the tread longitudinal direction, discontinuous concave grooves or hemispherical grooves on both side surfaces of a vulcanized tread. Was absorbed and absorbed (conventional example 1). In addition, as another measure, when creating a retreaded tire (when vulcanized treads are joined and integrated), an adhesive rubber sheet is attached to the part where peeling occurs (both ends of the tread) to increase the compression strain. Was relaxed and absorbed (No. 2 of the conventional example).

[0005]

In the conventional example 1, it is difficult to deepen the depth of the groove due to the structure, and the depth of the groove becomes shallow and the function of relaxing and absorbing the compressive strain is weakened. ..
On the other hand, in the conventional example 2, a step portion is formed by bonding the adhesive rubber sheets, and air may remain when vulcanization molding is performed due to the step portion, which may lead to adhesion failure. Not only does the surface curvature in the radial direction of the vulcanized tread differ because the rubber sheet part is thicker,
Since it is an unvulcanized rubber sheet, the vulcanization time may be increased and the productivity may be reduced.

Therefore, an object of the present invention is to provide a vulcanized tread for retreaded tires that solves the above problems and problems.

[0007]

According to the present invention, an unvulcanized cushion rubber layer 3 is interposed to vulcanize and vulcanize the base tire 2 so that they are joined and integrated together, and a compression strain relaxation absorbing portion 4C is provided at both ends. In the vulcanized tread 4 for retreaded tires, the following technical measures are taken to achieve the above-mentioned object.

That is, according to the present invention, the rubber 5 having the same quality as the cushion rubber layer 3 or having a low heat generation is integrally provided in the joint area of the both ends of the tread to the cushion rubber layer 3 or the joint area of the entire surface including both ends of the tread. It is characterized by that, by configuring in this way, there is no stepped portion, there is no air trap at the time of vulcanization, the vulcanization time does not increase and the adhesiveness without impairing the productivity, The cushioning property can be improved (Claim 1).

Further, since the thickness of the rubber 5 is 1 to 7 mm, the wear is not significantly reduced (Claim 2). Further, the joint area at both ends of the rubber 5 is 5 mm or more. Due to this, the function of relaxing and absorbing the compression strain can be maintained (claim 3).

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show a first embodiment, reference numeral 1 is a retreaded tire, and a base tire 2 is buffed by removing old tread by cutting or the like, and a buffed surface 2A is formed on the buffed surface 2A. The unvulcanized cushion rubber layer 3 is interposed and the vulcanized tread 4 is pressure-bonded and vulcanized to be joined and integrated.

In the vulcanized tread 4, a tread pattern 4B is formed on a strip-shaped main body 4A having a substantially flat trapezoidal shape, and compression strain relaxation absorption portions 4 are provided at both ends of the strip-shaped main body 4A.
C is provided. The compression strain relaxation absorbing portion 4C formed at both ends of the tread is a U-shaped cross-section groove, which is formed continuously or discontinuously in the tread longitudinal direction,
In FIGS. 1 (A) and 1 (B), rubbers 5 of the same quality as or low in heat generation of the rubber layer 3 are integrally provided in the joining regions of the both ends of the tread to the cushion rubber layer 3.

In the first embodiment shown in FIGS. 1A and 1B, the rubber 5 has a substantially trapezoidal cross section, and the relaxation absorbing portion 4C is formed on the rubber 5 itself, and the rubber 5 is added together with the belt-shaped body 4A. The interface (joint surface) with the vulcanized and unvulcanized cushion rubber layer 3 is formed as a flat surface without a step. FIG. 2 shows a second embodiment, and unlike the first embodiment in that the rubber 5 has a substantially triangular cross section, the rubber 5 itself has a relaxation absorbing portion 4C.

FIG. 3 shows a third embodiment, in which the belt-shaped main body 4 is used.
The relaxation absorbing portions 4C are formed at both ends of A, and the belt-shaped rubber 5 is vulcanized and adhered over the entire joint area including both ends of the tread. In the fourth embodiment shown in FIG. The relaxation absorbing portion 4C is formed on the rubber 5, and the thickness of the rubber 5 is changed to a wedge shape from both end portions of the tread toward the center portion of the tread. In the fifth embodiment shown in FIG. Is formed into a flat trapezoid that forms the bottom of the tread.

Here, the cushion rubber layer 3 is preferably a rubber material mainly composed of natural rubber and having a strong adhesive force and an adhesive force and a low dynamic heat generation.
A rubber material having a lower dynamic heat generation than the tread rubber can be adopted by blending synthetic rubber or natural rubber and synthetic rubber. The thickness of the rubber 5 is preferably 1 mm or more (the total thickness is 2 mm or more because the cushion rubber layer 3 is usually about 1 mm at the time of tire production) to 7 mm or less (total thickness 8 mm or less).

If the thickness of the rubber 5 is less than 1 mm, its function cannot be expected, and if it exceeds 7 mm, a cushion rubber layer 3 having relatively weak abrasion resistance appears on the surface before the tread use limit, which causes a large reduction in abrasion. It is because Further, the rubber 5 can be spread over the entire surface as shown in FIGS. 3 to 5, but when it is provided at both ends of the tread as shown in FIGS. 1 and 2, it is provided with a width of 5 mm or more so as to absorb and absorb the compression strain. Will be played sufficiently.

In the manufacture of retreaded tires, a molded tire is put in a vulcanization can and pressure-bonded, and therefore, generally 5 to 8 kg.
/ Cm ² of compressed air is filled, the compressed air is heated to about 90 to 130 ° C. using a heater or steam (indirect), and the molded tire is heated for about 180 to 300 minutes to perform vulcanization. In this case, the compressed air filled in the vulcanizer is compressed air at a temperature close to room temperature. A lot of energy costs and heating time are spent to heat the compressed air to 90 to 130 ° C.

Therefore, a commonly used compressor is equipped with a device for cooling the compression heat generated when compressed air is produced to a temperature close to room temperature. By removing (or lowering the cooling capacity), the compression heat generated when creating compressed air (5 kg / cm ² When creating compressed air, approximately 160 ° C, 8
It is possible to reduce the energy cost for heating the compressed air cooled to room temperature and the time for heating it by using compressed air of approximately 190 ° C in the case of compressed air of kg / cm ² and to expand the volume depending on the temperature. By using this air, it became possible to reduce the amount of air used.

Further, if the generated heat of compression is directly injected into the vulcanization can, the quality of the tire may be impaired due to the high temperature.
The cooling capacity of the cooling device was lowered, and the temperature of the compressed air was adjusted to about 110 ° C. in consideration of the temperature decrease. To reduce the temperature of the compressed air in the can that occurs over time, use a temperature controller. When the temperature decreases, inject hot compressed air while adjusting the internal pressure so that the temperature inside the can becomes 100 ± 5 ° C. Is desirable.

[0019]

EFFECTS OF THE INVENTION A retreaded tire prepared by using the vulcanized tread according to the present invention, which has been described in detail above, has compressive strain propagated from the ground contact surface, and the thickness of the rubber inserted inside the cushion rubber layer and the tread. By increasing the amount, the ability to alleviate and absorb the compression strain is enhanced, and when the rubber has low heat generation, thermal deterioration is improved and peeling of the tread can be reliably prevented.

Furthermore, since it is not necessary to increase the thickness of the unvulcanized cushion rubber layer, it is possible to improve the adhesiveness and cushioning property without wasting the vulcanizing time of pressure bonding and without impairing the productivity.

[Brief description of drawings]

1A is a partial cross-sectional view of a retreaded tire according to the first embodiment, and FIG. 1B is an enlarged view of the same.

FIG. 2 is an enlarged view of the second embodiment.

FIG. 3 is an enlarged view of the third embodiment.

FIG. 4 is an enlarged view of the fourth embodiment.

FIG. 5 is an enlarged view of the fifth embodiment.

[Explanation of symbols]

 1 Rehabilitated tire 2 tires 3 Cushion rubber layer 4 Vulcanized tread 4C Compressive strain relaxation absorber 5 Rubber

Claims (3)

[Claims] 1. An unvulcanized cushion rubber layer (3) is interposed and pressure-vulcanized to a base tire (2) so as to be joined and integrated, and both ends are provided with compression strain relaxation absorbing portions (4C). In the vulcanized tread (4) for retreaded tires, the same quality as the cushion rubber layer (3) is formed in the joint area of the tread end portions to the cushion rubber layer (3) or the entire joint area including the tread end portions. A vulcanized tread for retreaded tires, which is integrally provided with a rubber (5) having a low heat generation. 2. The vulcanized tread for retreaded tire according to claim 1, wherein the rubber (5) has a thickness of 1 to 7 mm. 3. The vulcanized tread for retreaded tires according to claim 1, wherein the joint area at both ends of the tread of the rubber (5) is 5 mm or more.