JP2002001730A - Method for manufacturing bladder for vulcanizing tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a bladder for vulcanizing a tire capable of shortening a vulcanizing time in a vulcanizing mold of the bladder and suppressing a shortage of a lifetime of the bladder in the case of using for vulcanizing the tire. SOLUTION: The method for manufacturing the bladder for vulcanizing the tire comprises the steps of primarily vulcanizing the bladder 6 for vulcanizing the tire in the vulcanizing mold 1, and then secondarily vulcanizing the bladder in an atmosphere having an oxygen concentration of 5% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bladder for vulcanizing a tire, and more particularly, to a method for shortening the vulcanization time in a vulcanizing mold of a bladder and for using the tire for vulcanizing a tire. The present invention relates to a method for manufacturing a bladder for tire vulcanization that can suppress a shortening of the life of the bladder.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of tires, a bladder made of a rubber bag is inserted into the inner surface of an unvulcanized tire placed in a vulcanizer, and steam or warm water is injected into the bladder and heated. The tire is vulcanized by inflating the bladder.

[0003] In the manufacture of this tire vulcanizing bladder, unvulcanized rubber is allowed to flow into a vulcanizing mold and the rubber is vulcanized by heating to form a bladder shape. Since it takes a long time to vulcanize this bladder, remove the bladder early from the vulcanizing mold in a semi-vulcanized state, put the bladder into the heating chamber and heat it again for secondary vulcanization. Accordingly, a production method has been proposed which shortens the vulcanization time in a vulcanization mold and improves productivity.
However, when the bladder is heated and vulcanized in a heating chamber, the rubber in the bladder is degraded by oxygen in the air. However, there is a problem that the service life of the bladder is shortened, such as that the bladder is damaged at an early stage or the surface condition is deteriorated to be rough.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the vulcanization time of a bladder in a vulcanizing mold and to suppress the shortening of the life of the bladder when used for tire vulcanization. It is an object of the present invention to provide a method for producing a tire vulcanizing bladder.

[0005]

According to the present invention, a tire vulcanization is performed by first vulcanizing a tire vulcanizing bladder in a vulcanizing mold and then secondary vulcanizing in an atmosphere having an oxygen concentration of 5% or less. A method for producing a sulfur bladder is provided.

As described above, by performing the secondary vulcanization of the tire vulcanizing bladder in an atmosphere having an oxygen concentration of 5% or less, the rubber is prevented from being oxidized and degraded by oxygen during the secondary vulcanization. Shortening of the life of the bladder can be suppressed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a state in which a tire vulcanizing bladder is primarily vulcanized in a vulcanizing mold, and FIG. 2 shows an unvulcanized rubber flowing into the vulcanizing mold. It is sectional drawing which shows the state just before making it.

The vulcanizing mold 1 comprises an upper mold 2, a core 3, and a lower mold 4. First, as shown in FIG. 2, an unvulcanized rubber 5 which is a material for a tire vulcanizing bladder is placed in a lower mold 4 and then the upper mold 2 and the core 3 and the lower mold 4 are vertically moved. 1 and closed as shown in FIG. 1, the unvulcanized rubber 5 is allowed to flow into the vulcanizing mold 1, and is heated and vulcanized to form a tire vulcanizing bladder 6.

The primary vulcanization of the tire vulcanizing bladder is as follows:
Instead of completely vulcanizing the rubber, the vulcanizing mold 1 is opened early and the tire vulcanizing bladder 6 is taken out. The degree of the primary vulcanization may be any condition as long as the bladder shape is maintained and a porous state (void) due to undercure is not generated.

Next, the primary vulcanized bladder for tires is placed in an oven or the like and subjected to secondary vulcanization in an atmosphere having an oxygen concentration of 5% or less, so that the bladder for tire vulcanization is completely vulcanized. Is done. By replacing oxygen in the atmosphere with nitrogen or the like, the oxygen concentration is set to 5% or less, preferably 0%, and the amount of oxygen is significantly reduced compared to air in the atmosphere having an oxygen concentration of 21%. Secondary vulcanization of the bladder in this atmosphere can suppress oxidative deterioration of the rubber.

[0011]

EXAMPLES The present invention will be further described with reference to the following examples, but it goes without saying that the scope of the present invention is not limited to these examples. Examples 1 and 2 and Comparative Examples 1 to 3 Tire vulcanizing bladders using butyl rubber are shown in Table 1 below.
The primary vulcanization in the mold and the secondary vulcanization in an oven were carried out under the vulcanization conditions shown in the following. The oxygen concentration in the oven during the secondary vulcanization was adjusted by replacing part or all of the air with nitrogen. About the obtained tire vulcanizing bladder, the rubber properties shown below and the life when used for tire vulcanization were measured, and the results are specified in Table 1.

A 300% modulus, a tensile strength, and an elongation at break were measured in accordance with JIS K6251. Hardness JIS A hardness was measured according to JIS K6253. Bladder Life A bladder for tire vulcanization was used for tire vulcanization, and the number of times of vulcanization of the tire until the bladder life was exhausted, such as the bladder being damaged or the bladder surface being deteriorated and rough, was indicated by an index.

[0013]

[Table 1]

As shown in Table 1 above, Comparative Example 1 involved only the primary vulcanization step, so that the vulcanization time using the vulcanizer required 60 minutes and the bladder productivity was poor. Comparative Example 2 using atmospheric air as the secondary vulcanization atmosphere, and
In Comparative Example 3 using an oxygen concentration of 10% for the secondary vulcanization atmosphere, the bladder life was significantly reduced. In comparison, in Examples 1 and 2, the vulcanization time using a vulcanizer was reduced to 30 minutes, and
Good results were obtained in that the shortening of the bladder life was also suppressed.

[0015]

According to the present invention, the vulcanizing time of the bladder in the vulcanizing mold is reduced by subjecting the vulcanizing bladder to secondary vulcanization in an atmosphere having an oxygen concentration of 5% or less. The shortening of the life of the bladder when used for vulcanization can be suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a tire vulcanizing bladder is primarily vulcanized in a vulcanizing mold.

FIG. 2 is a cross-sectional view showing a state immediately before an unvulcanized rubber flows into a vulcanizing mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vulcanization mold 2 Upper mold 3 Core 4 Lower mold 5 Unvulcanized rubber 6 Tire vulcanizing bladder

Claims (1)

[Claims] 1. A method for producing a tire vulcanizing bladder, comprising: first vulcanizing a tire vulcanizing bladder in a vulcanizing mold and then secondary vulcanizing in an atmosphere having an oxygen concentration of 5% or less.