JPS6242768A - Method for irradiating electron beam - Google Patents

Abstract

PURPOSE:To reduce the consumption of inert gas by firstly irradiating a part of the absorbed dose necessary for a material to be irradiated in an inert gas atmosphere and then irradiating the balance absorbed dose in air. CONSTITUTION:With respect to a method for irradiating an electron beam on the material to be irradiated and curing a coated film, the inert gas is firstly supplied into an irradiation chamber 2 from a gas supply port 3 to form the inert gas atmosphere, then a film 5 is rewound from a rewinding device 11, a resin is coated on the surface by a coater 10, an electron beam E which is a part of the necessary absorbed dose is irradiated from an electron beam irradiating device 1 to precure the coated film and the penetration of oxygen into the coated film is made difficult. The film 5 is wound by a winding device 12, the pressure in the irradiation chamber 2 is made positive, air is charged, the film is again set on the rewinding device 11 and the balance dose is irradiated from the electron beam irradiating device 1. Consequently, the consumption of the inert gas can be remarkably reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electron beam irradiation method for irradiating an object with an electron beam to cure, for example, a coating film, and particularly relates to an electron beam irradiation method for curing a coating film, etc. Concerning consumption reduction methods.

[Conventional technology]

When an object to be irradiated is irradiated with an electron beam, a conventional method has been adopted in which the irradiation is performed in an atmosphere of an inert gas such as nitrogen gas.

In the following, the hardening of the coating film by electron beam irradiation (
This will be explained using the case of Guaring as an example.

When a coating film is cured by electron beam irradiation, the coating film is cured by radical polymerization, but if oxygen is present in the irradiation atmosphere at that time, a phenomenon occurs in which the radicals are consumed by oxygen and polymerization becomes impossible. Therefore, in order to lower the oxygen concentration in the irradiation atmosphere (for example, to several hundred ppm or less), the irradiation chamber is filled with an inert gas such as nitrogen gas, and electron beam irradiation is performed in the inert gas atmosphere.

[Problem that the invention seeks to solve]

When curing a coating film with an electron beam, it is usually necessary to irradiate the electron beam at a dose (absorbed dose) of about IM rad to a dozen or more M rad, although this varies depending on the type of resin in the coating film. Conventionally, this &'[ is irradiated at once or in multiple steps, but in both cases the irradiation is done in an inert gas atmosphere, and the amount of inert gas at that time is usually several tens of Nm3/hr. The problem is that a large amount of inert gas is consumed.

Therefore, an object of the present invention is to provide an electron beam irradiation method that can reduce the amount of inert gas consumed.

[Means for solving problems]

The electron beam irradiation method of this invention first irradiates a part of the required absorbed dose of the object to be irradiated at once or in multiple doses in an inert gas atmosphere, and then irradiates the remaining 8a amount once in air. It is characterized by being irradiated in two or more times.

[Effect]

The initial electron beam irradiation in an inert gas atmosphere causes oxygen to penetrate into the irradiated object.Therefore, there is no problem even if the remaining dose is irradiated in air (and it also causes the inert gas to be irradiated). Gas consumption is reduced.

〔Example〕

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the electron beam irradiation method according to the present invention. This device uses film 5
an unwinding device 11 for unwinding the film, and a coater 10 for applying a coating film to the surface of the film 5. A conveyor line 6 that has rollers 7 and the like and conveys the film 5, a winding device 12 that winds up the film 5, and an inert gas such as nitrogen gas that is provided in the middle of the conveyor line 6 and is supplied with an inert gas such as nitrogen gas from a gas supply port 3. It consists of an irradiation chamber 2 in which the electron beam is supplied, an electron beam irradiation device 1 that irradiates the coated film (irradiation object) 5 with an electron beam E, and the like. Note that 8 is an X-ray shielding plate.

During electron beam irradiation, first, only a portion of the required absorbed dose is irradiated in an inert gas atmosphere. That is, an inert gas is supplied into the irradiation chamber 2 from the gas supply port 3 to create an inert gas atmosphere therein.

Then, the film 5 is unwound from the unwinding device 11, a resin (coating film) is applied to the surface of the film in the coater 10, and the film is exposed to a part of the required absorbed dose for the film 5 in an inert gas atmosphere in the irradiation chamber 2. A dose of electron beam E is irradiated from an electron beam irradiation device 1 to precure the coating film. This makes it difficult for oxygen to penetrate into the coating film.

Then, the film 5 is wound up by the winding device 12. In the above case, air flows into the irradiation chamber 2 from the outside by creating a positive pressure inside the irradiation chamber 2 and allowing the inert gas to leak out little by little from the inlet/outlet of the conveyor line 6. It is preferable to prevent

The remaining dose is then delivered in air. That is, in this example, the film 5 wound up by the winding device 12 is set again in the unwinding device 11, is supplied to the conveyor line 6 without passing through the coater 10, and the remaining dose of the electron beam E is emitted in the irradiation chamber 2. The electron beam is irradiated by an electron beam irradiation device 1, and then wound up by a winding device 12. At this time, no inert gas is supplied to the irradiation chamber 2 from the gas supply port 3, and the atmosphere inside the irradiation chamber 2 is left as air. This is because the previous irradiation has made it difficult for oxygen to penetrate into the coating film, and subsequent irradiation in the air will not cause the same problem in curing the coating film. Furthermore, this method significantly reduces the amount of inert gas consumed.

FIG. 2 is a schematic diagram showing another example of an apparatus for implementing the electron beam irradiation method according to the present invention. To explain the difference from FIG. 1, in this device, two irradiation chambers 2a, 2b and two electron beam irradiation devices 1a, 1b are provided in the middle of the conhair line 6, and the irradiation chamber 2a side is provided with two irradiation chambers 2a, 2b and two electron beam irradiation devices 1a, 1b. Only the inert gas is supplied from the gas supply port 3. That is, the film 5 coated with resin is first irradiated with an electron beam E in an inert gas atmosphere in the irradiation chamber 2a from the electron beam irradiation device 1a at a dose corresponding to a part of the required absorbed dose, and then in the irradiation chamber 2b. The remaining amount of electron beam E is irradiated in air from the electron beam irradiation device 1b. The film 5 is then wound up by a winding device 12 to become a product. Note that 13 is a partition plate that partitions the irradiation chambers 2a and 2b, but the conveyor line 6 may be separated into left and right sides at the partition plate 13. Further, in this embodiment, an inert gas flows into the irradiation chamber 2b from the irradiation chamber 2a side, but in this case, the irradiation chamber 2b has an atmosphere with an oxygen concentration of 5.
There is no need to control the amount to 00 ppm or less, and therefore there is no need to install an inert gas supply port in the irradiation chamber 2b.

In the above apparatus, unlike the apparatus shown in FIG.
The so-called divided irradiation described above can be performed continuously without resetting the irradiation device to the unwinding device 11. Therefore, productivity is very good.

Next, more specific examples of the present invention and comparative examples based on conventional methods are shown in the table. The table shows an example when the required absorbed dose is irradiated in two steps.
When 3 Mrad was irradiated at once in a nitrogen atmosphere (Comparative Example 1), ■ When irradiated in a nitrogen atmosphere in two 1° 5 Mrad doses (Comparative Example 2), and ■ The first 1.5
Mrad indicates the characteristics of the cured coating film when irradiated in a nitrogen atmosphere and 1.5 Mrad for the second time in air (Example).

(The following is a margin.) As can be seen from the table, the tensile strength was higher and a tougher film was obtained by split irradiation (Comparative Example 2, Example). In particular, in the examples, the first irradiation is carried out in a nitrogen atmosphere to pre-cure, making it difficult for oxygen to penetrate into the coating film, so even if the second irradiation is carried out in air, good curing is achieved. Ta.

Moreover, in the example, compared to comparative example 2, about 50 m3 of nitrogen gas could be saved per hour. In other words, by irradiating the electron beam in parts as in the above example, not only can the consumption of inert gas be saved, but depending on the resin of the coating film, it may be better to irradiate the electron beam at once in an inert gas atmosphere. It was found that a coating film with similar characteristics could be obtained.

Finally, although the above explanation is based on the case where irradiation is performed once in an inert gas atmosphere and once in air, each or either of them may be irradiated multiple times. . Furthermore, although the above description has been made using the example of curing a paint film, this invention is also applicable to other applications, such as processing of objects to be irradiated by electron beam irradiation in an inert gas atmosphere, such as modification of various plastics, cross-linking of rubber, etc. Of course, it can be widely applied to In addition, the shape of the object to be irradiated in this case is not limited to the film shape as described above, but may be other shapes such as a plate shape.

〔Effect of the invention〕

As described above, according to the present invention, the amount of inert gas consumed can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the electron beam irradiation method according to the present invention. FIG. 2 is a schematic diagram showing an example of an apparatus for carrying out the electron beam irradiation method according to the present invention. 1, la, 1b---Electron beam irradiation device, 2.2a.

Claims (1)

[Claims] (1) When irradiating an irradiated object with an electron beam, first irradiate a portion of the required absorbed dose of the irradiated object at once or in multiple doses in an inert gas atmosphere, and then irradiate the remaining dose. An electron beam irradiation method characterized by irradiation in air at once or in multiple steps.