JP7583246B2 - How to clean tire curing bladders - Google Patents

Description

The present invention relates to a method for cleaning a tire vulcanization bladder, and more specifically, to a method for cleaning a tire vulcanization bladder that removes adhering dirt while ensuring the releasability of the outer surface of the tire vulcanization bladder, allowing it to be used repeatedly.

When vulcanizing a green tire, a tire vulcanization bladder is expanded inside the green tire placed in a tire vulcanization mold, and the green tire is heated while being pressurized. A release agent is often applied to the outer surface of the vulcanization bladder to prevent adhesion with the inner surface of the vulcanized tire (see, for example, Patent Document 1). Unwanted dirt adheres to this outer surface as the vulcanization is repeated, and as the dirt increases, it affects the appearance quality of the vulcanized tire. For this reason, the tire vulcanization bladder is replaced with a new one after it has been used for a specified period or a specified number of times, for example.

When a tire curing bladder is replaced with a new one, it is often only dirty on the outer surface, but the bladder itself (the bladder base material) still has sufficient durability. Therefore, there is room for improvement in order to repeatedly use curing bladders with a healthy base material without wasting them.

JP 2009-83466 A

The object of the present invention is to provide a method for cleaning a tire vulcanization bladder that removes adhering dirt while ensuring releasability of the outer surface of the tire vulcanization bladder, allowing it to be used repeatedly.

In order to achieve the above-mentioned object, the method for cleaning a tire vulcanization bladder of the present invention is a cleaning method for removing dirt that has adhered to the surface of a release agent layer of a tire vulcanization bladder, the outer surface of which is covered with a release agent layer, during vulcanization of a green tire, the method being characterized in that the dirt is a component of a rubber composition that forms the green tire, and a solvent is applied to the surface, the dirt is dissolved in the solvent while leaving the release agent layer, and the dirt is removed from the surface.

According to the present invention, dirt adhering to the release agent layer covering the outer surface of the bladder is dissolved in the applied solvent while the release agent layer remains. Therefore, the outer surface of the bladder is free of dirt and remains covered with the release agent layer, ensuring releasability and enabling the bladder to be used repeatedly.

FIG. 2 is an explanatory diagram illustrating a tire vulcanization bladder as viewed from the front. FIG. 2 is an explanatory diagram illustrating the tire vulcanization bladder of FIG. 1 in a plan view. FIG. 3 is an explanatory diagram illustrating the left half of the tire vulcanization bladder of FIG. 2 in a vertical cross-sectional view. FIG. 4 is a partially enlarged view of FIG. 3 . 1 is an explanatory diagram illustrating a tire vulcanization bladder cleaning device as viewed from the front with the right half of the vulcanization bladder in vertical section; FIG. 6 is an explanatory diagram illustrating the cleaning device of FIG. 5 in a plan view. FIG. 4 is a graph illustrating the change over time in the degree of dissolution of the stain and the release agent layer. 5 is an explanatory diagram illustrating a state in which the stain in FIG. 4 has been dissolved in a dissolving liquid and removed. FIG. 13 is an explanatory diagram illustrating another cleaning device as viewed from the front with the lower half of the vulcanization bladder in vertical section; FIG.

The method for cleaning a tire vulcanization bladder of the present invention will be described below based on the embodiment shown in the figure.

The tire vulcanization bladder 10 (hereinafter referred to as the bladder 10) illustrated in Figures 1 to 4 is a cylindrical body with both ends open. The dashed line CL in the figure indicates the position of the cylindrical axis of the bladder 10. The outer surface 13 of the bladder 10, which is the subject of cleaning in the present invention, is covered with a release agent layer 12. The base material of the bladder 10 is formed from vulcanized rubber, so the base material surface 11 is vulcanized rubber. The inner surface 14 of the bladder 10 is not covered with a release agent layer 12, so the base material surface 11 is exposed as is.

The release agent that forms the release agent layer 12 has the function of preventing adhesion between the base surface 11 of the bladder 10 and the vulcanized tire, and allowing the tire to be smoothly peeled off from the bladder 10. The release agent layer 12 is formed from a known release agent such as a fluororesin or silicone. The thickness of the release agent layer 12 varies depending on the size of the tire to be vulcanized, but is generally about 10 μm to 200 μm, for example.

In this embodiment, the thickness of the release agent layer 12 is equal to or greater than the general thickness, for example, 100 μm or more. The upper limit of the thickness of the release agent layer 12 is, for example, 500 μm.

When the bladder 10 is repeatedly used to manufacture tires by vulcanizing green tires, dirt X gradually adheres to the surface of the release agent layer 12, and the amount of dirt X adheres to the surface increases. The dirt X is a rubber composition (a component of the rubber composition) that forms the green tire. As the amount of dirt X adheres increases, the bladder 10 adheres more strongly to the vulcanized tire, making it difficult to peel the bladder 10 from the tire. In addition, unevenness caused by the dirt X is formed on the inner surface of the vulcanized tire. In the figure, the shaded area indicates the dirt X, and the release agent layer 12 and dirt X are drawn to be exaggerated and thick.

The inventors of the present application analyzed a number of bladders 10 with dirt X attached and found that, under the same conditions of use, the amount (accumulation) of dirt X increases with the number of times it is used, but the release agent layer 12 does not wear out significantly and its thickness remains almost the same. In addition, they found that, under the same conditions of use, the degree of accumulation of dirt X is substantially the same even if the thickness of the release agent layer 12 is different.

In the present invention, the outer surface 13 of the bladder 10 is cleaned, for example, after the bladder 10 has been used for a specified period of time or a specified number of times. During cleaning, a solvent D is applied to the surface of the release agent layer 12, and dirt X adhering to this surface is dissolved by the solvent D while the release agent layer 12 remains. In the figure, dirt X is scattered (dotted), but the degree of adhesion of dirt X varies, and it may adhere in the form of a thin film over a wide area.

An example of a procedure for cleaning the bladder 10 is as follows:

As illustrated in Figures 5 and 6, the cleaning device 1 used in this embodiment includes a freely movable arm 3, a processing head 2 held at the tip of the arm 3, a nozzle 2a installed on the processing head 2, a dissolving liquid tank 7 connected to the processing head 2 via a hose connected to a pump, a booth 5, and a control unit 8 that controls the movements of the arm 3, the pump, the processing head 2, etc. The rear end of the arm 3 is rotatably connected to a base 4.

The solvent tank 7 stores the solvent D, which is pumped to the processing head 2 (nozzle 2a) by a pump. When the release agent layer 12 is formed from a fluorine-based release agent, acetone or toluene is used as the solvent D. This is because these solvents D dissolve the dirt X, but fluorine-based release agents are difficult to dissolve.

The bladder 10 is installed inside the booth 5, and the inner surface 14 is covered with a protective material 9 that blocks the solvent D. It is recommended to close both end openings of the bladder 10 and apply internal pressure to slightly expand the bladder 10 before cleaning.

The treatment head 2 and the nozzle 2a are moved to a desired position inside the booth 5, while spraying the solvent D toward the surface of the release agent layer 12, so that the solvent D is applied to the surface of the release agent layer 12 so as to cover the entire range of the outer surface 13. The application of the solvent D is not limited to being performed while the bladder 10 is kept stationary, and the solvent D can also be applied while the bladder 10 is rotated about its cylindrical axis CL.

The arm 3 can be controlled to move along the outer surface 13 based on the external shape data of the bladder 10, or can be moved manually. In this embodiment, the inner surface 14 of the bladder 10 is covered with a protective material 9 to prevent the applied solvent D from adhering to the inner surface 14. The solvent D dissolves the dirt X, but also dissolves the vulcanized rubber base material of the bladder 10. There is a risk that the base material of the bladder 10 will dissolve in the solvent D and cause the bladder 10 to deteriorate, so to avoid this risk, the inner surface 14 is protected from the solvent D by the protective material 9.

It is advisable to determine in advance the degree of dissolution of the dirt X and the release agent layer 12 by the solvent D, and to determine the cleaning conditions based on these determined degrees of dissolution. Specifically, as shown in FIG. 7, the change over time in the degree of dissolution (degree of reduction) of the dirt X and the release agent layer 12 to which the solvent D has been applied is determined. FIG. 7 shows data Q1 and Q2 for two types of release agent layers 12, and data Qx for the dirt X.

Then, based on the data in FIG. 7, the elapsed time when the dissolution of the release agent layer 12 is within the allowable range and the dirt X is sufficiently dissolved and removed is determined. In FIG. 7, the release agent layer 12 shown by data Q1 does not dissolve at all in the solvent D and the initial amount remains, while the release agent layer 12 shown by data Q2 is only slightly dissolved. The dirt X shown by data Qx dissolves in the solvent D and the remaining amount decreases over time, until at the elapsed time t, the entire amount is dissolved and removed. Then, this determined elapsed time t is determined as the appropriate cleaning time for leaving the solvent D applied (adhered) to the surface of the release agent layer 12.

By applying (attaching) the solvent D to the surface of the release agent layer 12 for an appropriate cleaning time, as shown in FIG. 8, the dirt X is sufficiently dissolved in the solvent D and removed from the surface of the release agent layer 12. The release agent layer 12 is hardly dissolved in the solvent D, or is not dissolved excessively. After the dirt X is removed from the surface of the release agent layer 12, the solvent D is washed off from the bladder 10 to complete the cleaning. The protective material 9 is removed from the inner surface 14.

The release agent layer 12 remains on the outer surface 13 of the bladder 10 after cleaning. In other words, the outer surface 13 is covered with the release agent layer 12, ensuring releasability. Therefore, this bladder 10 can be used again to vulcanize green tires, just like when it was new, by utilizing the existing release agent layer 12. This allows the bladder 10, whose base material is still sound, to be used repeatedly without being wasted.

As mentioned above, it is preferable to make the initial thickness of the release agent layer 12 larger than the general thickness, or 50 μm or more, and more preferably 80 μm or more, since this widens the range of appropriate cleaning times. This also makes it possible to increase the number of times the bladder 10 can be cleaned and reused. As mentioned above, even if the release agent layer 12 is made thicker, the amount of dirt X that adheres to it does not increase.

A cleaning device 1 as exemplified in Fig. 9 may also be used. In this cleaning device 1, a dissolving agent D is stored in a processing container 6. The surface of the release agent layer 12 of the bladder 10 is immersed in this dissolving agent D to remove the dirt X. For example, the bladder 10 is laid down on its side and rotated about the cylindrical axis CL while the lower part is immersed in the dissolving agent D, whereby the dirt X can be dissolved and removed while the dissolving agent D is stirred.

Reference Signs List 1 Cleaning device 2 Processing head 2a Nozzle 3 Arm 4 Base 5 Booth 6 Processing container 7 Solvent tank 8 Control unit 9 Protective material 10 Tire vulcanization bladder 11 Base surface 12 Release agent layer 13 Outer surface 14 Inner surface D Solvent X Dirt

Claims (4)

1. A cleaning method for removing dirt that has adhered to a surface of a release agent layer of a tire vulcanization bladder, the outer surface of which is covered with a release agent layer, during vulcanization of a green tire, comprising:
the dirt is a component of a rubber composition forming the green tire,
A method for cleaning a tire vulcanization bladder, comprising applying a solvent to the surface , dissolving the dirt in the solvent while leaving the release agent layer, and removing the dirt from the surface. The method for cleaning a tire vulcanization bladder according to claim 1, in which the dissolving agent is applied to the surface of the vulcanization bladder without adhering to the inner surface of the vulcanization bladder. The method for cleaning a tire vulcanization bladder according to claim 1 or 2, in which the degree of dissolution of the dirt and the degree of dissolution of the release agent layer by the dissolving agent are grasped in advance, and the cleaning time for which the dissolving agent is applied to the surface is determined based on the degree of dissolution thus grasped. The method for cleaning a tire vulcanization bladder according to any one of claims 1 to 3, wherein the release agent layer is formed from a fluorine-based release agent, and toluene or acetone is used as the solvent.

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