JPH0372290A - Continuous measuring method for amount of low-energy electron beam - Google Patents

Abstract

PURPOSE:To enable execution of continuous measurement and monitoring by applying an electron beam continuously onto a film-form substance which is running and by taking out a transmitted electron beam as a current. CONSTITUTION:Electron beams 8 accelerated under a high voltage and in high vacuum pass through an irradiation window 7 and are transmitted through a film-form substance 15 which is running, and part of them falls on an electrode 9 located just below. The electron of the electron beam 8 caught thereby passes through an ammeter 10 and proceeds to the ground. This ammeter 10 is fitted in a pair discretely from others on an electrode plate provided in a plurality in the width direction, and a current value thereof is recorded continuously in a recorder 12 through an amplifier 11. Thereby it can be monitored continuously whether a change in the amount of the electron beams 8 at the time of irradiation in a regular operation, deflection of the amount in the width direction at that time, or the like occurs or not.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the use of electron beams to continuously crosslink so-called film-like materials such as various films, sheets, and coated films. This invention relates to a method for continuously measuring electron dose.

[Conventional technology]

The electron beam generates thermoelectrons by heating a tungsten filament with electricity in a high vacuum (10-5 Tart or less), and at the same time charges a negative high voltage (150KV to 500KV) so that the filament side becomes a cathode. By using a clone repulsion saw, negatively charged electrons are accelerated to the grounded irradiation window, which is the anode side, and taken out into the atmosphere or inert gas through the irradiation window. By irradiating the material surface with electrons, it is ionized or activated to cause a polymerization reaction.

This electron beam irradiation dose evaluation method has conventionally been used by Far
Film dosimeters such as Radiochromic dosimeters, blue cellophane dosimeters, and cellulose triacetate dosimeters are commercially available from West Technology, etc., but all of these dosimeters are attached to the top of the object to be irradiated and placed under the irradiation window. This method measures the change in absorbance due to blue coloring and decolorization by passing the electron beam through it, and indirectly measures the dose on a batch-by-batch basis. Similarly, continuous measurement was not possible because the film dosimeter was pasted across the width of the object to be irradiated.

[Problems to be solved by the invention] These film dosimeters change color or bleach due to sunlight or fluorescent light, and absorb humidity in the atmosphere, so they require considerable effort to handle and are subject to large errors. There is a drawback that it can easily occur.

Furthermore, it can only be measured in batches by attaching it to the object to be irradiated, and when continuously irradiating a continuously moving film-like object, it is necessary to continuously monitor the irradiation dose, but continuous measurement is difficult. There were problems such as.

The present invention has been made in view of the above problems,
The object thereof is to provide a method for continuously measuring the irradiation dose of an electron beam while continuously irradiating a moving film-like object without the above-mentioned drawbacks.

[Means for solving problems]

That is, the present invention continuously irradiates a moving film-like object with an electron beam from an irradiation device, and receives the transmitted electron beam by an electrode placed directly below the film-like object and extracts it as an electric current to reduce the irradiation dose. This invention relates to a method for continuously determining the low-energy electron dose, which is characterized by continuous measurement and monitoring.

The following explanation will be given with reference to the drawings. As shown in FIG.
The electrode 9 is installed at a position where it can capture the . A conductive wire electrically connected to this electrode is led out of the irradiation device and connected to the negative terminal of the ammeter 10. Also, ammeter 10
The positive terminal of is grounded. The Ti flow value flowing here is continuously recorded by a recorder 12 via an amplifier 11.

FIG. 2 shows the structure of the electrode 9. Although there are three sets of electrode plates 21, this is not restrictive.

There are cases in which one electrode is large enough to cover the entire surface, and there are also cases in which a plurality of electrodes, three or more electrodes are used in the width direction, but three sets are shown in the diagram for illustration purposes. Furthermore, although the shape of the electrode Fi21 will be described using a rectangle, the present invention is not particularly limited to this. The material of the electrode plate 21 is preferably heat resistant and corrosion resistant. An electrical insulating plate 18 is attached on top of the pedestal 17. The electrode plate 21 is placed on top of this, and is installed so as to be electrically insulated from the pedestal 17. Each electrode Fi, 21
Connect the conductive wire 20 to the terminal so that no contact failure occurs.

The material of the conducting wire 20 is desirably heat resistant and corrosion resistant, and preferably has a sufficient cross-sectional area. As the electron beam continues to be irradiated, the kinetic energy of the electrons is converted into thermal energy.
The temperature is quite high, but if the wire is coated with vinyl or the like, the coating material will carbonize and break down, causing a short circuit inside the device and making accurate measurements impossible. Further, the generated carbonized gas adheres to and contaminates the titanium foil of the irradiation window 7, and the transmission of the electron beam 8 is significantly reduced.

Therefore, for the conducting wire 20, a method must be taken such as passing a highly heat-resistant coated wire or a bare wire through the ceramic tube.

Further, if the conducting wire 20 directly receives the transmitted electron beam 8, it will act as an electrode, so this point needs to be taken into consideration.

[Effect]

As shown in FIGS. 1 and 3, the electron beam 8 accelerated in a high voltage and high vacuum is emitted after passing through the titanium foil of the irradiation window 7, and then passing through the traveling film-like material 15. A portion of this falls on the electrode 9. The electrons of the electron beam 8 captured here pass through the ammeter 10 and proceed to the ground. This current value is
The data are continuously recorded by the recorder 12 via the recorder 12.

As a result, it is possible to check whether there are any fluctuations in the dose of the electron beam 8 during steady-state irradiation or unevenness in the dose in the width direction.
Can be continuously monitored.

The present invention provides a very useful solution to the conventional problem in which it has been difficult to manage the dose in the width direction and the entire length of the film-like material 15.

[Example] Hereinafter, an example will be described in which an apparatus as shown in FIGS. 2 and 3 is used.

For the electrode Fi21, a titanium foil having a thickness of 11.5 μm, a width of 10 mm, and a length of 60 m5 was used. A bare copper wire was used as the conducting wire 20, and was passed through a ceramic tube to prevent it from coming into contact with the pedestal 17 and the electron beam irradiation body, and to prevent it from being directly exposed to the electron beam.

As the membrane material 15, a polyethylene film having a thickness of 60 μm was run at a speed of 50 m/min. At an accelerating voltage of 165 KV, the absorbed dose on this polyethylene film surface was 3.
0. 4.8.6.5. 8. Settings were made for each of ORad.

Under these conditions, there was no film, one film, two films, and an adhesive (7.9 μm thick) between the two films.
The transmitted dose was measured using the measuring electrodes 9 for each case in which the two electrodes were sandwiched.

The results are shown in Table 1 and FIG.

Table 1 As shown in Figure 4, there is a proportional relationship between the absorbed dose and the electrode current, so by measuring the transmitted dose,
The absorbed dose on the film can be indirectly controlled. Using this method, the dose can be monitored across the width and entire length of the product without stopping the production line.

For example, even if a rod-shaped tungsten filament 1 reaches the end of its life after long-term operation and a failure occurs in electron beam irradiation, it can be dealt with immediately. As an equipment measure, it is possible to set upper and lower limits for the electrode current value, and if the electrode current value does not fall within these limits, an alarm is sounded or the line is stopped. In terms of product support, it is now possible to read and track record charts, identify and inspect product defects, and play an important role in quality control! It will become a thing.

[Effects of the Invention] As described above, according to the present invention, it is possible to continuously measure and monitor the electron dose to a moving film-like object, and it is possible to provide products with stable quality.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the low-energy electron beam irradiation device, FIG. 2 is a front view and plan view of the measurement electrode, and FIG. 3 is a circuit diagram of the electron beam irradiation device and the measurement electrode device. FIG. 4 is a diagram showing the relationship between the absorbed dose on the film-like material and the electrode current. Description of symbols 1, rod-shaped tungsten filament 2, control electrode 1 3. Control electrode 2 Vacuum chamber shielding part Electron beam ammeter recorder Guide roll Winding roll Insulation plate Heat-resistant outer tube conductor (ceramic tube)

Claims (1)

[Claims] 1. The moving film-like object is continuously irradiated with an electron beam from an irradiation device, and the transmitted electron beam is received by an electrode placed directly below the film-like object and extracted as an electric current to continuously adjust the irradiation dose. A method for continuously measuring low-energy electron doses.