JPH11188741A - Method and apparatus for cleaning vulcanizing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for cleaning a vulcanizing mold by removing the residue comprising a plastic material formed on the vulcanizing mold repeatedly used in the vulcanizing molding of a plastic product or the like. SOLUTION: An electrode 21 provided with air orifices communicating with jet orifices is arranged to the outer surface of a shower pipe and voltage is applied across the electrode 21 and a vulcanizing mold 10 to form a high frequency plasma region between the electrode and the mold and a reactive gas plasma is allowed to act on the vulcanizing mold 10 through the plasma region. The reactive gas plasma is ejected to the inner surface of the vulcanizing mold arranged in a vacuum treatment tank 1 from a large number of the jet orifices of the shower pipe to be allowed to act on the vulcanizing mold 10 to remove the elastomer residue on the surface of the mold by ashing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention removes residues from the above-mentioned materials generated in a vulcanization mold used repeatedly for vulcanization molding of rubber products such as rubber tires, vibration-proof rubbers, and plastic products such as elastomers. The present invention relates to a method and an apparatus for cleaning a vulcanizing mold.

[0002]

2. Description of the Related Art Elastomer products, especially rubber tire products and vibration-proof rubber products, satisfy the required performance. In addition to blending a reinforcing material such as black, it is necessary to blend a vulcanization accelerator and various chemicals for maintaining durability.

[0003] When vulcanizing and molding the unvulcanized rubber composition prepared as described above, a chemical reaction such as a crosslinking reaction generally occurs at a high temperature close to 200 ° C. Not only does it increase, but also gasifies partially, as a result, the rubber composition and the molding surface of the vulcanizing mold, as well as the very narrow gaps in the mating surfaces of the mold and the holes such as vent holes for air venting It is unavoidable that the chemical reaction product adheres firmly as a residue every time vulcanization and molding is carried out, albeit in a trace amount. By repeating this vulcanization molding many times, the residue is deposited with an unnoticeable thickness. This occurs not only in the rubber composition but also in other elastomers in a similar manner.

[0004] Vulcanized residues firmly adhered and deposited on such a vulcanizing mold adversely affect the appearance and quality of molded products.
It is necessary to remove the residue from the vulcanizing mold.

Conventionally, as a method of removing the residue generated in the above vulcanizing mold by ashing, a reactive gas is introduced into a vacuum processing tank, and a high-frequency A voltage is applied between two electrodes connected to a power supply to generate plasma in the reactive gas, and the plasma is applied to a vulcanizing mold disposed in a vacuum processing tank to form a surface of the mold. There is known a method for removing an elastomer residue (see JP-A-6-285868 and JP-A-8-21).
Nos. 6164 and 8-244041).

A reactive gas, which has been converted into plasma in advance, is ejected from a number of ejection holes of a shower tube toward an inner surface of a vulcanization mold placed in a vacuum processing tank, and the plasma is applied to the vulcanization mold. There is also known a method of cleaning a vulcanizing mold in which a converted reactive gas is caused to act to remove an elastomer residue on the surface by ashing (JP-A-8-300366).

As described above, the cleaning of a vulcanizing mold by plasma is known, but in a vulcanizing mold cleaning apparatus using a high-frequency capacitively coupled plasma, the structure of the apparatus itself is relatively simple. However, since the plasma density is low, cleaning takes time, and the utilization efficiency of the reactive gas used is low, it is necessary to use a large amount of gas.On the other hand, using a different method such as a microwave downflow method In the method using high-density plasma, it may be difficult to uniformly blow the gas over the whole, and it is difficult to clean a large mold.

The present invention has been made in view of the above circumstances, and it is possible to shorten the cleaning time, reduce the supply and discharge of the reactive gas, and reduce the size and shape of the mold to be cleaned. It is an object of the present invention to provide a method and an apparatus for cleaning a vulcanizing mold, which can be satisfactorily cleaned regardless of the type.

[0009]

In order to achieve the above object, the present invention provides the following method and apparatus for cleaning a vulcanizing mold.

[0010] Claim 1: A reactive gas, which is preliminarily converted into plasma, is ejected from a large number of ejection holes of a shower tube toward an inner surface of a vulcanization mold disposed in a vacuum processing tank, thereby forming the vulcanization mold. A method for cleaning a vulcanizing mold, in which a reactive gas converted into plasma is applied to ashing to remove an elastomer residue on the surface, an air hole communicating with the ejection hole is provided on an outer surface of the shower tube. A voltage is applied between the electrode and the vulcanizing mold to form a high-frequency plasma region therebetween, and the reactive gas converted into plasma is applied through the plasma region. A method for cleaning a vulcanization mold, wherein the method is applied to a vulcanization mold.

In another preferred embodiment, a vacuum processing tank, one end of which is inserted into the tank, and a plasma generator which is provided at the other end,
A reactive gas introduction pipe through which the reactive gas converted into plasma by the plasma generator flows, and one end of the introduction pipe existing in the vacuum processing tank connected to the reactive gas introduced from the introduction pipe; A shower tube having a large number of ejection holes for ejecting gas into the vacuum processing tank, and an inner surface of the vulcanizing mold arranged in the vacuum processing tank facing the ejection hole of the shower tube. In a vulcanizing mold cleaning apparatus in which a plasma-forming reactive gas is sprayed to ashing and removing an elastomer residue on the surface of the vulcanizing mold, the outer surface of the shower tube is communicated with the ejection hole. An electrode provided with an air hole is provided, and this electrode and the vulcanizing mold are connected to a high-frequency power source, respectively, and a voltage is applied between the electrode and the vulcanizing mold, so that a high-frequency plasma region is formed. The shape And, characterized that the vulcanization mold cleaning apparatus that it has to blow the plasma are reactive gases vulcanizing mold through the plasma zone.

In the present invention, by combining a microwave down-flow plasma with a high-frequency capacitively coupled plasma, a reactive gas passes through the high-density plasma at the time of gas introduction, thereby being excited into a highly reactive state. It is sprayed onto the vulcanizing mold without attenuating, which is further stimulated by high frequency plasma near the mold. Therefore, according to the present invention, both high-speed cleaning with active species in a more active excited state by high-density plasma and uniform cleaning of the entire vulcanization mold by high-frequency plasma are achieved, thereby shortening the cleaning time. And the gas use efficiency is increased, and the amount of gas used and the amount of exhaust gas can be reduced. Furthermore, according to the apparatus of the present invention, it is possible to perform excellent cleaning regardless of the size and shape of the mold.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a vulcanizing mold cleaning apparatus according to the present invention will be described in more detail with reference to the drawings.

In FIG. 1, a vacuum processing tank 1 has a container upper part 2 which can be vertically separated from each other and can be sealed at a lower position.
A vacuum pump not shown in the container lower part 2-2. The container 2 has a container 2 having a container lower part 2-1 and a container lower part 2-2. A suction unit 3 to be connected is provided. Prior to starting the cleaning operation of the vulcanizing mold 10, the vacuum pump is operated and the container 2
The inside air is exhausted in the direction of arrow A in the figure, and the air pressure inside the container 2 is set to a so-called medium vacuum to high vacuum of, for example, 10 ^-1 to 10 ^-5 Torr. In the illustrated example of the vacuum processing tank 1, the lower part 2-2 of the container is fixed to the floor surface Fs or the like by, for example, a plurality of columns 4 (only two are shown in the figure). The wheel conveyor 5 holds the vulcanizing mold 10 set on the surface plate 11.

Numeral 14 denotes a plasma flow shower pipe having a cylindrical outer peripheral surface. The shower pipe 14 has a large number of ejection holes 15 formed on the outer periphery thereof, and these ejection holes 15 are formed in the vulcanizing mold 10. And one end thereof is connected to one end of a reactive gas introduction pipe 16 protruding into the vacuum processing tank 1. Here, the shower tube 14 at the same time forms the cylinder having a space portion S ₁₄ in the interior of the peripheral surface, discoid plasma flow induced provided at the lower end of the inlet tube 16 to the inner peripheral surface of the cylindrical member 16 1 and the guiding member 16-
Connecting the first and the space portion S ₁₄ of the inner space S _16-1 and showering tube 14 to each other. As described above, although providing a plurality of ejection holes 15 penetrating in the space portion S ₁₄ on the entire surface of the outer periphery of the shower tube 14, the other of these jetting holes 15 are aligned in vertical and horizontal alignment, vertical direction (inlet pipe 16 extending direction) or a staggered arrangement in the lateral direction. The material of the shower tube 14 is quartz or alumina.

The upper end of the introduction pipe 16 is connected to a pipe 19 passing through a plasma flow generating furnace 18 via a connector 17. Frequency 300MHz-30GHz, preferably 1G
The output power from the microwave power supply unit 20 at 10 Hz to 10 GHz is transmitted to the plasma flow generation furnace 18, and the reactive gas to be flowed in the direction of the arrow B is turned into plasma by the discharge of the microwave power. At that time, the frequency, the supplied power amount, and the inflow amount (SCCM) of the reactive gas are selected so that the density of the neutral active species in the plasma flow becomes a desired value. As the reactive gas, either oxygen gas alone or a mixed gas of the main component oxygen gas and the auxiliary component halide gas, preferably CF ₄ gas, is used as the reactive gas, and oxygen (O, O ₂ , O ₃ ) A radical, CF ₄ radical, is obtained. Plasma flow generator 18
Is not limited to a single unit. Preferably, a plurality of furnaces or a plurality of furnaces are connected in parallel to the connector 17, and microwaves are transmitted to each furnace.

Reference numeral 21 denotes a cylindrical electrode provided on the outer peripheral surface of the shower tube 14 and having a large number of ventilation holes 22 communicating with the ejection holes 15. The electrode 21 is connected to a high frequency power supply 23. At the same time, the vulcanizing mold 10 is also connected to the high-frequency power source 23 via the surface plate 11 to form a high-frequency plasma region P between the electrode 21 and the vulcanizing mold 10. In addition,
24 is a matching box.

Using the above vulcanizing mold cleaning device, the vulcanizing mold 1
In removing the elastomer residue on the inner surface of the plasma flow generation furnace 18, the plasma flow generated in the plasma flow generation furnace 18
9, the connector 17, inlet tube 16 and the guide member 16-1 is guided inside reached space S ₁₄ of the showering tube 14, wherein the vulcanization mold through the vent holes 22 of the plurality of ejection holes 15 and electrodes 21 10 are uniformly ejected in the direction of the arrow toward the entire inner peripheral surface. That is, even during the series of operations, the vacuum pump is operated to continuously exhaust the gas in the vacuum processing tank 1 from the suction unit 3, and the pressure inside the processing tank 1 is constantly set to 0.01 to 10 Torr.
This is because the pressure is kept constant within the range of r.

In this case, in the present invention, the plasma flow acts on the vulcanization mold 10 through a high-frequency plasma region P formed between the electrode 21 and the vulcanization mold 10. The plasma flow is further activated and acts uniformly on the vulcanizing mold 10, whereby high-speed cleaning with active species in a more active excited state by microwave downflow high-density plasma and mold by high-frequency plasma An even cleaning of the whole is achieved.

Here, as the reactive gas, oxygen gas alone or a mixed gas with a halide gas containing oxygen gas as a main component can be suitably used.
O ₂ and O ₃ , and the halide gas is F
(Fluorine), CF ₄ , NF ₃ , SF _{6 and the} like can be suitably used, but are not particularly limited.

The amount of inflow of the reactive gas (SCCM) is
Although it is appropriately adjusted, for example, when a mixed gas of oxygen gas and halide gas is used, oxygen gas 100 to 10
The halide gas is preferably set to 0 to 50%, particularly preferably 5 to 30% with respect to 000 SCCM, particularly 100 to 2000 SCCM.

Further, the conditions for generating the high frequency capacitively coupled plasma are appropriately selected.
z, especially 1-100 MHz, power 1-20 KW, especially 5
Preferably, the condition is 10 to 10 KW.

According to the present invention, the reactive gas is subjected to a two-stage plasma treatment, so that the reactive gas can be efficiently converted into plasma, the waste of the reactive gas is avoided, and the supply amount and the discharge amount are reduced. The amount can be reduced. Since the plasma processing achieves a high-density plasma flow, the ashing speed for the residue is dramatically improved.

Next, the effects of the present invention will be specifically shown by the following experimental examples. [Experimental example] Japanese Unexamined Patent Publication No. Hei 8 (1996), which comprises eight split molds (segments Nos. 1 to 8) around a cylindrical electrode having an outer diameter of 480 mm and a height of 220 mm and a maximum inner diameter of 550 mm. using the apparatus shown in -216164 discloses, a mixed gas of O ₂ gas and CF ₄ gas as a reactive gas O ₂ 5
00 SCCM and CF ₄ at a flow rate of 250 SCCM (O ₂ : C
(F ₄ = 2: 1 flow ratio) into the vacuum processing tank. In this case, the reactive gas pressure was maintained at 1.5 Torr.

In this state, a voltage is applied between the electrode and the vulcanizing mold under the conditions of a frequency of 13.56 MHz and a power of 5 kW,
The treatment was performed for 120 minutes (Comparative Example 1).

Further, using the apparatus disclosed in Japanese Patent Application Laid-Open No. 8-300366, the above mixed gas was supplied at a frequency of 2.45 GHz and
The treatment was performed for 120 minutes in the same manner as described above, except that the plasma flow formed by microwave discharge at a power of 5 KW was blown onto the inner surface of the vulcanizing mold (Comparative Example 2).

Next, using the apparatus shown in FIG. 1, a plasma flow formed by microwave-discharging the mixed gas under the conditions of a frequency of 2.45 GHz and a power of 5 kW is blown to a vulcanizing mold, A voltage was applied between the mold and the vulcanizing mold under the conditions of a frequency of 13.56 MHz and a power of 5 KW to form a high-frequency plasma region, and the plasma flow was further processed through the high-frequency plasma region for 60 minutes ( Example).

Each segment No. of the vulcanizing mold Table 1 shows the results of evaluating the temperature, the degree of incineration of the residue, and the incineration uniformity based on the following criteria immediately after the treatments 1 to 8. The degree of incineration (average of incineration ) was evaluated as 5 points. The larger the degree of incineration, the better the incineration state, and 4 points or more were regarded as acceptable levels. Ashing uniformity A sample that could be almost uniformly incinerated and removed was evaluated as O, and a sample that did not was evaluated as X.

[0029]

[Table 1]

[0030]

According to the present invention, it is possible to efficiently and surely remove the elastomer residue of the vulcanizing mold in a short time and by reducing the amount of gas used and the amount of exhaust gas.

[Brief description of the drawings]

FIG. 1 is a schematic view of a vulcanizing mold cleaning apparatus according to one embodiment of the present invention.

[Description of Signs] 1 Vacuum processing tank 2-1 Upper container 2-2 Lower container 10 Vulcanizing mold 18 Plasma flow generator 20 Microwave power supply unit 21 Electrode 23 High frequency power supply

Claims (2)

[Claims] A reactive gas, which is preliminarily converted into plasma, is ejected from a plurality of ejection holes of a shower tube toward an inner surface of a vulcanization mold disposed in a vacuum processing tank, and a plasma is applied to the vulcanization mold. In the method of cleaning a vulcanizing mold, a reactive gas is acted on to remove the elastomer residue on the surface by ashing, an electrode provided with an air hole communicating with the ejection hole on the outer surface of the shower tube. And applying a voltage between the electrode and the vulcanizing mold to form a high-frequency plasma region between the electrodes and allowing the reactive gas converted into plasma to pass through the vulcanizing mold through the plasma region. A method for cleaning a vulcanizing mold, which is applied to a mold. 2. A vacuum processing tank, one end of which is inserted into the tank, and a plasma generating device provided on the other end side, and a reactive gas introduced by which the reactive gas converted into plasma by the plasma generating device flows. A pipe and a shower pipe which is connected to one end of the introduction pipe in the vacuum processing tank and has a large number of ejection holes for ejecting the plasma-formed reactive gas from the introduction pipe into the vacuum processing tank. The plasma-forming reactive gas is sprayed on the inner surface of a vulcanizing mold disposed in the vacuum processing tank with the inner surface facing the ejection hole of the shower tube, and the elastomer on the surface of the vulcanizing mold is sprayed. In a vulcanizing mold cleaning apparatus that removes residues by ashing, an electrode having an air hole communicating with the ejection hole is provided on an outer surface of the shower tube, and the electrode and the vulcanizing metal are provided. Each mold has high circumference By connecting to a microwave power source and applying a voltage between the electrode and the vulcanizing mold, a high-frequency plasma region is formed, and the reactive gas converted into plasma is passed through the plasma region to the vulcanizing mold. A vulcanizing mold cleaning device characterized by spraying.