JP2003337199A - Method for cleaning electron beam penetration window and electron beam radiation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for removing a deposit on an electron beam penetration window of an electron beam radiation apparatus. <P>SOLUTION: A method for cleaning the electron beam penetration window for radiating the electron beam cleans the electron beam penetration window by blowing an active gas or an inert gas containing the active gas against the electron beam penetration window of an electron beam source or a vicinity of the same. The electron beam radiation apparatus comprises a jet nozzle for jetting the active gas or the inert gas containing the active gas provided in the vicinity of the electron beam penetration window of the electron beam source. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and apparatus for removing deposits on an electron beam transmission window of an electron beam irradiation apparatus.

[0002]

2. Description of the Related Art In recent years, paints, printing inks, adhesives, etc. which are cured by electron beam irradiation such as electron beam, ultraviolet ray, etc. have a processing speed higher than that of conventional thermosetting dry type paints, printing inks, adhesives etc. It has come to be put into practical use because it has advantages such as high speed, pollution-free by solvent-free, and miniaturization of electron beam irradiation device.

However, among such paints, printing inks, adhesives, etc., there are those which generate vaporized components in the electron beam irradiation chamber during vaporization, vaporization, or reaction.
There was a case where the material physically bounced due to carrier vibration in the irradiation chamber, wind pressure of the replacement gas (inert gas), etc., and was deposited on the electron beam transmission window of the electron gun. If such a deposit is present on the electron beam transmitting window, there are cases where the electron beam is blocked or heat is generated by absorbing the electron beam, and in the worst case, the transmitting window is damaged. In order to avoid these problems, it is essential to remove the deposit, but the electron beam transmission window of the electron gun uses a very thin thin film typified by titanium and aluminum to improve the electron beam transmission rate. However, it is virtually impossible to physically remove (wiping, etc.), and in the past, measures such as periodical replacement of the transparent window were made.

[0004]

However, in the method as described above, it is necessary to open the vacuum of the electron gun chamber to the atmosphere in order to replace the electron beam transmission window, and even for a large apparatus, the apparatus can be stopped for a week. In some cases,
There have been problems with reduced productivity and increased maintenance costs.

[0005]

Means for Solving the Problems As a result of experiments conducted by the present inventors in view of the above problems, the object to be irradiated is vaporized and evaporated in an electron beam irradiation chamber, or an evaporation component is generated in a reaction process, or In order to remove deposits adhering to the electron beam transmission window by physically bouncing due to carrier vibration in the irradiation chamber, wind pressure of inert gas, etc., an active gas should be added to the electron beam transmission window and its vicinity. It was found that it is very effective to remove the deposits (organic substances, etc.) deposited in the electron beam transmission window by irradiating the electron beam from the electron beam source while spraying.

That is, the first invention irradiates an electron beam while blowing an active gas or an inert gas containing the active gas onto the electron beam transmitting window of the electron beam source and / or its vicinity. This is a method of cleaning a transparent window. The second invention is that the active gas is oxygen gas and the oxygen gas is 10
The above method for cleaning an electron beam transmission window is characterized by containing 0 ppm or more. A third invention is an electron beam irradiation method characterized in that the electron beam transmission window is cleaned by the above method automatically or manually when the electron beam irradiation apparatus is started and / or stopped. A fourth invention is an electron beam irradiation apparatus characterized in that an injection nozzle of an active gas or an inert gas containing an active gas is provided in the vicinity of an electron beam transmission window of an electron beam source. A fifth aspect of the invention is the electron beam irradiation apparatus described above, wherein the injection nozzle also serves as a cooling nozzle for the electron beam transmission window. A sixth invention is the above-mentioned electron beam irradiation apparatus in which the electron beam transmission window of the electron beam source is made of silicon or a silicon compound.

By using the deposit removing method of the electron beam transmitting window and the electron beam irradiating device according to the present invention, it becomes possible to easily remove the deposit adhered during the irradiation process, and to recover the device for a short time. It is possible to provide an electron beam irradiation method and apparatus that achieve easy maintenance.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of an electron beam irradiation apparatus showing an embodiment of the present invention. Reference numeral 1 denotes an electron beam source, the inside of which is kept vacuum and has an electron gun 4 and an electron beam transmission window 5. The electrons generated by the electron gun 4 are accelerated by the high voltage applied to the electron gun 4, become an electron beam 9, pass through the electron beam transmission window, and are taken out to the irradiation chamber 3. The electron beam source used in the present invention has a low acceleration voltage, preferably 150 or less, more preferably 100 kV or less, and an irradiation device having a vacuum tube type electron beam irradiation unit is preferable. The vacuum tube type electron beam irradiation device is different from the type of device that irradiates an electron beam while constantly drawing a vacuum inside the drum, which is the electron beam generation part (electron beam source), because it is a vacuum tube type, so the electron beam generation part There is no need to vacuum.

A deposit removing gas injection nozzle 6 is installed in the vicinity of the electron beam transmission window of the electron beam source, and a gas flow 8 can be blown toward the electron beam transmission window. The deposit removal gas injection nozzle is designed so that the active gas is supplied from the gas supply pipe 7 and the gas can be blown to the electron beam transmission window. In addition, when the flow of the gas ejected from the deposit removal gas injection nozzle is directly blown to the electron beam transmission window, and the electron beam transmission window is likely to be damaged, the gas is once discharged near the electron beam transmission window. It is also possible to use a gas stream with a reduced flow rate by applying a stream.

Further, the deposit-removing gas injection nozzle is used as a deposit-removing gas injection nozzle when a gas is used for cooling the electron beam transmission window as seen in a normal electron beam irradiation device. You can share it. In this case, in the case where the gas species used at the time of electron beam processing and the gas used at the time of cleaning the transmission window are different, a mechanism (for example, a three-way cock) for selecting the gas species supplied to the deposit removal gas injection nozzle may be provided.

The active gas used for removing the deposit is one that can react with, combine with or activate the deposit, gasify or vaporize it, remove or reduce the deposit, and not deteriorate the electron beam transmission window. However, it is usually a mixed gas containing 100 ppm or more of oxygen gas in nitrogen gas, preferably 200 ppm or more, and more preferably 3 wt% or more (including air). . further,
A gas other than oxygen gas may be used as the active gas. If the deposit is a specific substance, it is also effective to use an active gas that is easily vaporized by reacting with or activating the substance. Generally, as the active gas, a reactive gas or the like that can react with, bond with or activate the deposit is used.

Reference numeral 2 denotes a transfer duct, which has a transfer roll 10 for transferring an object 11 to be irradiated and also has a function of blocking invasion of air from the outside and active energy rays.

When the deposits are continuously or continuously irradiated with an electron beam to paints, printing inks, adhesives, etc., some of the paints, printing inks, adhesives, etc. have electron beam irradiation chambers. Some of them generate vaporized components during vaporization, evaporation, and reaction, or they physically bounce due to carrier vibration in the irradiation chamber, wind pressure of inert gas, etc., and adhere to the electron beam transmission window. It may be accumulated.
For example, when an object to be flexographically printed with an ink consisting of 40 parts by weight of urethane acrylic oligomer and 60 parts by weight of pentaerythritol diethylene oxide adduct is irradiated with an electron beam, the deposit adhered to the electron beam transmissive window is a polymer of the ink composition. It is confirmed by analysis that it is a product.

To remove the deposit attached to the electron beam transmission window of the present invention, an electron beam is generated from the electron beam source while injecting an active gas or an inert gas containing the active gas from the deposit removal gas injection nozzle. Can be achieved. Although the cleaning mechanism of the present invention has not been analyzed in detail, it is considered that the deposit can be removed because the oxygen gas and the organic substance induce a chemical reaction or the like by the electron beam and become carbon dioxide gas.

It is desirable that the cleaning according to the present invention is performed periodically according to the operating conditions of the electron beam irradiation device. Normally, automatically when the electron beam irradiation device is started and / or stopped,
Or manually. It is also desirable to carry out the cleaning method of the present invention when the electron beam irradiation apparatus is in an operating state, i.e., idling, although the transfer of the irradiation object is stopped. That is, stop the electron beam irradiation device (print,
When coating etc. is stopped), it takes time to stabilize or stabilize the operation until operation.Therefore, it is common to keep the electron beam irradiation device in the operating state even if the transfer of the irradiation target is stopped. It can be done when idling.

Further, the electron beam irradiation apparatus of the present invention is an object to be cured, crosslinked or modified, for example, printing ink, paint,
It can be effectively applied to paper, metal, plastic film or sheet coated or formed with an adhesive agent, etc., but the electron beam irradiation apparatus according to the present invention is not limited in its use for curing, crosslinking or modifying an object to be irradiated. Not a thing.

[0018]

Example 1 In the electron beam irradiation apparatus shown in FIG. 1, 40 parts by weight of a urethane acrylic oligomer (Beamset 505A-6 manufactured by Arakawa Chemical Industry Co., Ltd.), pentaerythritol diethylene oxide adduct
(Shin Nakamura Chemical Co., Ltd.'s ATM-4E) 60 hours by weight of flexographically printed ink on the irradiated object for 2 hours at a transport speed of 50 m / min
When the print-curing reaction of the irradiated object was carried out by passing it, deposits adhered to the electron beam transmission window. At this time, from the deposit removal gas injection nozzle that is also used as the electron beam transmission window cooling gas injection nozzle, cooling is performed while blowing nitrogen gas at a flow rate of 20 (l / min) onto the electron beam transmission window. 50kV,
It was driven by 8 mA.

After that, the object to be irradiated is taken out from the electron beam irradiation apparatus, and oxygen gas is used as an active gas from the deposit removal gas injection nozzle which is also used as the electron beam transmission window cooling gas injection nozzle, and 20 (l / min) The electron beam source was operated at an accelerating voltage of 50 kV and 8 mA for 2 hours while spraying on the electron beam transmitting window at a flow rate.

As the electron beam source, a vacuum tube type electron beam irradiation tube (Min.
-A device with 20 EB) was used.

The purification effect of the electron beam transmission window in this experiment is shown.
Shown in 1. In the table,% means% by weight. Example 2 Table 1 shows the active gas injected from the deposit removal gas injection nozzle.
The same experiment as in Example 1 was performed except that the mixed gas (including Air) with the nitrogen gas having the oxygen gas concentration shown in was used. Comparative Example 1 An experiment similar to that of Example 1 was performed, except that the gas ejected from the deposit removal gas ejection nozzle was nitrogen gas. Comparative Example 2 The same experiment as in Example 1 was performed except that the electron beam irradiation source was not driven during the deposit removal treatment. Comparative Example 3 The same experiment as in Example 1 was performed except that the gas was not injected from the deposit removal gas injection nozzle.

In all the examples and comparative examples, no damage was observed on the electron beam transmission window.

When these Examples 1 and 2 and Comparative Examples 1 to 3 are compared, it is possible to irradiate with an electron beam while blowing an active gas or a gas containing an active gas to the electron beam transmission window and its vicinity. It can be seen that removing the deposits adhering to the electron beam transmissive window is very effective for cleaning the electron beam transmissive window.

[0024]

According to the present invention, the deposits on the electron beam transmission window can be easily removed and reduced, and the damage and replacement of the electron beam transmission window can be reduced or reduced. As a result, it is possible to eliminate the problems of reduced productivity and increased maintenance costs.

[0025]

[Table 1]

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an electron beam irradiation apparatus showing one embodiment of the present invention.

[Explanation of symbols]

1 electron source 2 transport duct 3 irradiation room 4 electron gun 5 Electron beam transparent window 6 Deposition removal gas injection nozzle 7 Gas supply pipe 8 gas flow 9 electron beam 10 Conveyor roll 11 Irradiated object

Claims (6)

[Claims] 1. A method for cleaning an electron beam transmission window, which comprises irradiating an electron beam while blowing an active gas or an inert gas containing an active gas onto the electron beam transmission window of an electron beam source and / or in the vicinity thereof. . 2. The active gas is oxygen gas, and the oxygen gas is 100
2. The method for cleaning an electron beam transmission window according to claim 1, wherein the method includes cleaning at ppm or more. 3. An electron beam irradiation method characterized in that the electron beam transmission window is cleaned by the method according to claim 1 or 2 when the electron beam irradiation apparatus is started and / or stopped. 4. An electron beam irradiation apparatus, characterized in that an injection nozzle of an active gas or an inert gas containing an active gas is provided in the vicinity of an electron beam transmission window of an electron beam source. 5. The electron beam irradiation apparatus according to claim 4, wherein the injection nozzle also serves as a cooling nozzle for the electron beam transmission window. 6. The electron beam irradiation apparatus according to claim 4, wherein the electron beam transmission window of the electron beam source is made of silicon or a silicon compound.