JPH1152098A - Electron beam irradiator and window foil for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a corrosion-proof window foil by using an aluminum-alloy foil as a metal foil and using what is formed by further coating a titanium layer coating the alloy foil with a hard coating as a window foil. SOLUTION: This device is equipped with an electron beam generating section 10 that extracts thermions emitted from a cathode as an electron beam and accelerates it, an irradiation chamber 20 where an object is irradiated with the electron beam and a window foil 32 that is used as a partition between a vacuum atmosphere in the electron beam generating section 10 and an irradiated atmosphere in the irradiation chamber 9 and extracts the electron beam. The window foil 32 is constituted by containing an aluminum-alloy foil, a titanium film for coating the surface of the aluminum-alloy foil on the side of the irradiation chamber and hard coatings for coating the titanium film. Consequently, the window foil 32 is obtained that has high electron beam transmissivity and is free from the occurrence of flaws in handling or the corrosion due to abrasion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam irradiator used for surface treatment, and more particularly to a window foil used for an electron beam irradiator used for curing or immediate drying of ink and for surface sterilization. And an electron beam irradiation apparatus using the same.

[0002]

2. Description of the Related Art In recent years, surface treatments such as curing, immediate drying, and surface sterilization of ink have been performed using ultraviolet rays or electron beams. However, in the method using ultraviolet rays, it is necessary to add a photopolymerization initiator, and since ultraviolet rays have a low transmission power, there is a problem that the inside of an opaque material such as a coloring paint cannot be treated. . Therefore, low-energy electron beams are mainly used for such surface treatment.

In a conventional low energy type electron beam irradiation apparatus, thermoelectrons emitted from a linear filament are taken out as an electron beam, and this electron beam is accelerated in a vacuum space in an accelerating tube and then passed through an irradiation window. Take out into the irradiation room. Then, target processing is performed by irradiating the object to be processed conveyed in the irradiation chamber. The irradiation window has a window foil for separating a vacuum atmosphere in the acceleration tube and an irradiation atmosphere in the irradiation chamber.
As the window foil, a metal having no pinhole and having mechanical strength enough to maintain a vacuum atmosphere in the acceleration tube, for example, a titanium foil having a thickness of 10 to 20 μm or an aluminum foil having a thickness of 10 μm is used. Usually, a titanium foil having a thickness of about 12.7 μm is most often used as a window foil because of its easy mechanical handling.

FIG. 1 shows a schematic configuration of an example of an electron beam irradiation apparatus. This electron beam irradiation apparatus is of a low energy type, and includes an electron beam generator 10, an irradiation chamber 20, and an irradiation window 30. The electron beam generator 10 has a terminal 12 for generating an electron beam and an acceleration tube 14 for accelerating the electron beam generated in the terminal 12 in a vacuum space (acceleration space). In order to prevent electrons from colliding with gas molecules and losing energy, the inside of the electron beam generator 10 is controlled to 10 ⁻⁶ to 10 ⁻⁷ by a diffusion pump or the like (not shown).
It is kept at Torr vacuum. The terminal 12 has a linear filament 12a that emits thermoelectrons, a gun structure 12b that supports the filament, and a grid 12c that controls thermoelectrons generated by the filament.

[0005] The irradiation chamber 20 includes an irradiation space 22 for irradiating an object to be processed with an electron beam. In this example, the irradiation space 22 inside the irradiation chamber 20 has an air atmosphere. The object to be processed moves from the right side to the left side in FIG. 1 by a transporting means such as a conveyor in which the irradiation space 22 is not shown. The irradiation window 30 includes a window foil 32 made of metal foil and a window foil 3.
And a window frame structure 34 for supporting the window foil and cooling the window foil. The window foil 32 separates a vacuum atmosphere in the electron beam generator 10 from an air atmosphere in the irradiation space 22, and extracts an electron beam to the irradiation chamber through the window foil 32. The window foil 32 provided at the boundary between the electron beam generator 10 and the irradiation chamber 20 has no pinholes, has a mechanical strength enough to maintain a vacuum atmosphere in the electron beam generator 10, and also transmits the electron beam. A metal having a small specific gravity and a small thickness is desirable for ease of use.

In such a low energy type electron beam irradiation apparatus, the acceleration voltage of the electron beam is as small as about 150 kV, and most of the electron beam is absorbed by the window foil. Aluminum having a lower density than titanium is suitable as a material for the window foil. However, aluminum is easily corroded by a reactive gas such as ozone generated by an electron beam.
No. 2, as in the electron beam irradiation apparatus shown in Japanese Patent Application Publication No.
Those coated with titanium of 2 to 1.0 μm are also used.

[0007]

However, Japanese Patent Application Laid-Open No.
In the window foil described in JP-A-20294, in which the surface of an aluminum foil is coated with titanium in a thickness of 0.2 to 1.0 μm, the titanium layer often scratches when the titanium coating side comes into contact with something during handling. In addition, even during normal use, the window foil remains
And the window foil is bent when the device is evacuated or opened to the atmosphere, and the contact portion with the window frame structure is worn. As a result, there is a problem that the scratched portion and the worn portion are corroded. Therefore, an object of the present invention is to provide an electron beam irradiation device provided with a window foil that does not cause corrosion due to scratching or abrasion.

[0008]

According to the present invention, there is provided an irradiation window in an electron beam irradiation apparatus, comprising: an aluminum alloy foil; a titanium film covering the aluminum alloy foil; and a hard film covering the titanium film. The present invention provides a window foil for use. Further, according to the present invention, an electron beam generator for extracting thermoelectrons emitted from a cathode as an electron beam and accelerating the electron beam, an irradiation chamber for irradiating an object to be processed with the electron beam, What is claimed is: 1. An electron beam irradiation apparatus, comprising: a window foil for separating a vacuum atmosphere in an electron beam generating section from an irradiation atmosphere in an irradiation chamber and extracting an electron beam, wherein the window foil is an aluminum alloy foil; It is an object of the present invention to provide an electron beam irradiation device comprising a titanium film covering at least a surface of the foil on the irradiation chamber side, and a hard film covering the titanium film. According to the present invention, it is possible to obtain an electron beam irradiation apparatus provided with a window foil that has a high electron beam transmittance and does not cause corrosion due to scratching or abrasion during handling.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A window foil in an electron beam irradiation apparatus according to the present invention comprises an aluminum alloy foil, a titanium film covering the aluminum alloy foil, and a hard film covering the titanium film. . Preferably, an aluminum alloy foil having a thickness of 5 to 20 μm is used as the metal foil, and the surface of the aluminum alloy foil on the irradiation chamber side is coated with titanium having a thickness of 0.03 μm or more, more preferably 0.05 μm or more. Is further 0.03 μm or more, more preferably 0.1 μm or more.
Coat with a hard coating of 05 μm or more.

The aluminum alloy foil preferably has a thickness of 5 to 20 μm. The reason why the thickness is set to 5 μm or more is that it is difficult to manufacture a thin film having no pinholes necessary for maintaining a vacuum at a thickness smaller than the above value. This is because it becomes large, and the advantage of changing from titanium to aluminum alloy foil is lost. More preferably, the thickness of the aluminum alloy foil is 10 to 15 μm. Here, as the aluminum alloy that can be used, pure aluminum, Al-
Cu-based, Al-Mn-based, Al-Si-based, Al-Mg-based,
Al-Mg ₂ Si based, include various alloys such as Al-Zn-based. In particular, Al-Cu-based and Al-Mg-based are preferred because they have excellent tensile strength.

In order to maintain high electron beam transmittance and prevent corrosion, it is necessary to coat titanium on the irradiation chamber side of the aluminum alloy foil. The thickness of the titanium film is preferably 0.03 μm or more in order to obtain a sufficient adhesion,
More preferably, it is 0.05 μm or more. As the titanium coating, one made of pure titanium can be used. Further, it is necessary to coat the surface of the titanium film with a hard coating in order to give the outermost surface sufficient hardness and abrasion resistance so that the outermost surface is hardly damaged. This hard coating preferably has a thickness of 0.03 μm, more preferably 0.1 μm.
It is not less than 05 μm.

The total thickness of the titanium layer and the hard coating layer is:
0.1-1 μm is preferred. When the total thickness of the titanium layer and the hard coating layer is 0.1 μm or less, the anticorrosion effect is insufficient, and when it is 1 μm or more, the aluminum alloy foil may be significantly curled due to the residual stress of the coating. It may be difficult to handle when attaching to a computer.
It is not preferable to directly coat the aluminum alloy foil with the hard coating because the adhesion is small and the aluminum alloy foil is easily peeled off. A preferred combination of the respective thicknesses of the titanium layer and the hard coating layer is a combination of a 0.03 to 1 μm titanium layer and a 0.03 to 1 μm hard coating layer. A more preferred combination is
0.05-0.5μm titanium layer and 0.05-0.5μ
m is a combination of hard coating layers. As the material of the hard coating, TiN, TiC, TiCN, TiO ₂ , Al
₂ O ₃ , AlTiN, AlN, CrN, Cr ₂ O ₃ , diamond, diamond-like carbon, SiO ₂ ,
SiC, SiN, CBN, and mixtures thereof can be used. Among them, titanium nitride (TiN) is preferable because it can be formed in the same process as titanium coating and can be relatively easily formed by a vapor deposition method, an ion plating method, or a reactive sputtering method.

The titanium and the hard coating are deposited by vacuum deposition, ion plating, sputtering, CV
It can be performed by various methods such as Method D, and is not particularly limited. As an example, FIG. 2 shows a schematic diagram of an apparatus for a vacuum deposition method that can be used to produce the window foil of the present invention. The vacuum container 41 provided with the diffusion pump 42 and the rotary pump 43 can be evacuated to 10 ^-5 Torr or less by the pumps 42 and 43. In a vacuum vessel 41, a titanium evaporation crucible 44 containing titanium therein, a hollow cathode type electron gun 45, a shutter 4
6, a vapor deposition roll 47, two pay-out / wind-up rolls 48, and a quartz oscillation type film thickness meter 49 are arranged. This apparatus uses an electron gun 4 in an argon atmosphere at a degree of vacuum of about 1 × 10 ⁻⁴ Torr.
From 5, the electron beam 50 is irradiated to the titanium in the crucible 44 for titanium evaporation, and the titanium is heated and evaporated by the heat of the electron beam. The evaporated titanium is partially ionized in the electron beam, accelerated by a potential difference from a deposition roll, and deposited on the aluminum alloy foil substrate 51. The deposited film thickness can be determined from the film forming speed measured by the quartz oscillation type film thickness meter 49 and the aluminum alloy foil substrate transfer speed.

When titanium nitride is used as the hard coating, it can be formed by the same process as that for coating titanium. That is, a nitrogen gas is introduced during the formation of titanium to generate titanium nitride, and a film of this titanium nitride is formed on the surface of the titanium film. At this time, a layer in which titanium is continuously changed to titanium nitride may be formed from the surface of the aluminum alloy foil to the surface of the irradiation chamber by gradually increasing the nitrogen gas introduction amount. Further, a graded composition layer of titanium and titanium nitride may be used, or two independent layers of titanium and titanium nitride may be formed.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which are not intended to limit the present invention. Although titanium nitride was used for the hard coating in the example, TiC, TiC
N, TiO ₂ , Al ₂ O ₃ , AlTiN, AlN, Cr
It goes without saying that N, Cr ₂ O ₃ , diamond, diamond-like carbon, SiO ₂ , SiC, SiN, CBN, and mixtures thereof can be widely used.

As Conventional Examples 1 and 2, a titanium foil having a thickness of 12.7 μm and an aluminum alloy foil having a thickness of 12.7 μm (type of alloy: Al-Mg alloy 505) were used as window foils.
2) was used. As Conventional Examples 3 to 7, a thickness of 12.7 μm
Of titanium alloy on the surface of the irradiation chamber side of the aluminum alloy foil of 0.05 μm, 0.1 μm, 0.2 μm, 1 μm, respectively.
One coated to a thickness of 2 μm was used.

The coating of titanium in Conventional Examples 3 to 7 was performed by a vacuum deposition method using an apparatus as shown in FIG.
Table 1 shows the results of examining the window foils of Conventional Examples 1 to 7 for electron beam transmittance and for the presence or absence of corrosion after a 50-hour irradiation test.

[0018]

[Table 1]

From Table 1, it can be seen that by changing the window foil base material from titanium foil to aluminum alloy foil, the amount of electron beam transmission increases and more effective use of X-rays becomes possible. On the other hand, aluminum alloy foil has a problem of corrosion due to ozone generated by an electron beam, but in conventional examples 3 to 6 in which the surface is coated with a titanium film to a thickness of 0.05 to 1 μm,
Basically, there was no corrosion, indicating corrosion resistance. Conventional examples 3 to 6
As for, scratches presumed to have occurred due to handling during attachment to the irradiation window and the like were observed in some titanium, and slight corrosion was observed in the scratched portions. The cause is
It is estimated that the hardness of the titanium film is insufficient,
It is considered that a thickness of 2 μm or less is likely to cause damage to the film. However, if titanium is coated with a thickness of more than 1 μm, it becomes difficult to handle the foil as described in JP-A-7-20294. In Conventional Example 7 coated with 2 μm of titanium, the curl of the aluminum alloy foil was remarkable due to the residual stress of the titanium film, making handling difficult.
Could not be used.

From the above, it has been found that, when an aluminum alloy foil is used as a window foil base material and the surface thereof is coated with a titanium film to a thickness of 0.05 to 1 μm, the amount of electron beam transmission increases and corrosion can be prevented. Was. However, if such a titanium film alone is used, it is corroded from scratches. Therefore, on an aluminum alloy foil having a thickness of 12.7 μm, 0.05 μm in Examples 1 to 3, 0.1 μm in Examples 4 to 5, 0.5 μm in Examples 6 to 8, and Example 9 respectively.
In the case of -10, coating with a titanium film having a thickness of 1.0 μm is performed,
Further, the titanium film was set to 0.0
5 μm, 0.1 μm in Examples 4 and 10, Examples 2 and 7
Was further covered with a titanium nitride film having a thickness of 0.5 μm and Examples 3, 5 and 8 having a thickness of 1.0 μm. The film formation method is
The same vacuum evaporation method as in the conventional example was used. After a titanium film is formed to a predetermined thickness, if the gas introduced into the holocathode electron gun is changed to nitrogen, the evaporated titanium reacts with the nitrogen gas in the atmosphere to generate titanium nitride. Thereby, a film of titanium nitride is formed on the base material.

The aluminum alloy foils having a thickness of 12.7 μm were covered with titanium nitride films having a thickness of 0.05 μm and 0.1 μm, respectively. Table 2 shows the results of examining the electron beam transmittance, the presence or absence of corrosion after 50 hours, and the presence or absence of surface flaws of the window foils of Conventional Example 2, Examples 1 to 10 and Comparative Examples 1 and 2.

[0022]

[Table 2]

The window foils of Conventional Example 2 and Comparative Examples 1 and 2 are highly corroded. In particular, Comparative Examples 1 and 2 in which only aluminum nitride foil is coated with titanium nitride have poor adhesion of the titanium nitride film. The titanium film peeled off, and ozone entered the interface, causing corrosion at that portion. In Examples 1 to 10,
By coating the surface of the aluminum alloy foil with a titanium film having a thickness of 0.05 μm or more, and further covering the surface with a titanium nitride film having a thickness of 0.05 μm or more, while maintaining a high electron beam transmittance, Corrosion could be prevented. In Examples 3, 5, 8, and 10 in which the sum of the thickness of the titanium film and the thickness of the titanium nitride film was larger than 1 μm, the aluminum alloy foil was curled, and the mounting operation to the irradiation window became difficult. Therefore, considering the mounting operation to the irradiation window,
The sum of the thickness of the titanium film and the thickness of the titanium nitride film is 0.1 to 1 μm, which is a range in which the aluminum alloy foil does not curl.
Was found to be more preferable.

[0024]

As is apparent from the above description, according to the present invention, an aluminum alloy foil is used as a metal foil, and the aluminum alloy foil is coated with titanium.
By using the titanium layer coated with a hard coating as a window foil, the electron beam irradiation apparatus having a window foil that is hardly corroded because the surface is hardly damaged can be obtained. Further, the electron beam irradiation apparatus of the present invention has a high electron beam transmission amount, so that there is no loss of the electron beam and the electron beam can be efficiently taken out into the irradiation room.

[Brief description of the drawings]

FIG. 1 is a schematic view of an electron beam irradiation apparatus conventionally used.

FIG. 2 is a schematic view of an apparatus for a vacuum deposition method that can be used to manufacture the window foil of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electron beam generation part 12 Terminal 12a Filament 12b Gun structure 12c Grid 14 Accelerator tube 20 Irradiation room 22 Irradiation space 30 Irradiation window 34 Window frame structure 41 Vacuum container 42 Diffusion pump 43 Rotary pump 44 Crucible for titanium evaporation 45 Hollow cathode type electron Gun 46 Shutter 47 Evaporation roll 48 Dispensing / winding roll 49 Crystal oscillation type film thickness gauge 50 Electron beam 51 Aluminum alloy foil substrate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Urano 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Inside the Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Masaki Kono Kannon Shinmachi 4 in Nishi-ku, Hiroshima City, Hiroshima Prefecture Chome 6-22 Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory

Claims (2)

[Claims] 1. An irradiation window foil for an electron beam irradiation apparatus, comprising: an aluminum alloy foil; a titanium film covering the aluminum alloy foil; and a hard film covering the titanium film. 2. An electron beam generating section for taking out thermoelectrons emitted from a cathode as an electron beam and accelerating the electron beam, an irradiation chamber for irradiating an object to be processed with the electron beam, What is claimed is: 1. An electron beam irradiation apparatus comprising: a window atmosphere for separating a vacuum atmosphere in a beam generation unit and an irradiation atmosphere in an irradiation chamber and extracting an electron beam, wherein the window foil is an aluminum alloy foil; An electron beam irradiation apparatus, comprising: a titanium film covering at least the surface on the irradiation chamber side; and a hard film covering the titanium film.