JPH1090500A - Method for irradiating object with active energy beam and object to be irradiated with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for irradiating an object with an active energy beam and an object to be irradiated with it which have little adverse effect on a working environment and can reduce the degree of an inactivation by an inactive gas. SOLUTION: If the acceleration voltage of an irradiating electron beam is 40kV or lower, the oxygen concentration of a part irradiated with the electron beam is adjusted to that in an approximate air atmosphere or lower and then an object is irradiated with the electron beam. If the acceleration voltage of an irradiating electron beam exceeds 40kV, the oxygen concentration is adjusted to the one shown by Y<=1.19×10<2> ×exp(-4.45×10<-2> ×X), letting the acceleration voltage (kV) = X and the oxygen concentration (%) in a part irradiated with the electron beam = Y, and then an object is irradiated with the electron beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accelerating electrons in a vacuum with respect to a coating material such as a coating material, a printing ink, an adhesive or the like provided on a base material, and applying the accelerated electrons to the coating material. The present invention relates to an active energy irradiation method for irradiating an object with an electron beam (EB) at ordinary pressure to cure or crosslink a coating material and the like, and to an active energy ray irradiated material.

[0002]

2. Description of the Related Art Electron beam curing has been proposed as a method for curing or crosslinking coating materials such as paints, printing inks and adhesives applied to substrates. Electron beam curing is a method in which electrons are accelerated by a voltage in a vacuum, the accelerated electrons are taken out into a normal pressure atmosphere such as air, and an object is irradiated with an electron beam (EB). Is usually 300 kV to 1 MV.

The advantages of curing and crosslinking by electron beam irradiation include the following. (1) It is environmentally friendly because it does not need to contain an organic solvent as a diluent.

(2) High curing speed (high productivity). (3) Less curing work area than heat drying. (4) Heat is not applied to the base material (applicable to heat-sensitive materials).

(5) Post-processing can be performed immediately (cooling, aging, etc. are unnecessary). (6) Since it is only necessary to control the electrical working conditions, it is easier to control than the temperature control during thermal drying.

(7) Since there is no need for an initiator and a sensitizer,
A product with less impurities can be produced (improved quality). By the way, in an electron beam curing apparatus generally used industrially, a polymerization reaction is caused by radicals generated by irradiating an object to be treated with an electron beam, whereby a polymer is formed and curing proceeds. in this case,
If oxygen is present in the irradiation chamber, radical polymerization is inhibited by the reaction between the growing radicals in the processed material and oxygen radicals generated by the electron beam. For this reason, generally 2
At present, irradiation is performed at an oxygen concentration of 500 ppm or less using nitrogen or the like even at a relatively low acceleration voltage of about 00 kV.

When an electron beam is irradiated in an air atmosphere, oxygen molecules are changed to ozone. Ozone is a substance that is extremely harmful to the human body. According to the recommendation of the allowable concentration of the Japan Society for Occupational Health (1992), the allowable concentration of ozone is 0.1 pp.
The ozone concentration is 0.1 ppm at the maximum and 0.05 pp on average according to the design standards of the Japan Air Cleaning Association.
m or less. Therefore, it is necessary to pay sufficient attention to ventilation and the like in the working environment at the time of electron beam irradiation. As a method of treating ozone, a method of decomposing ozone with activated carbon and reducing it to oxygen molecules is also used, but there are problems such as a short life of activated carbon, which is a serious problem in practical use.

[0008] For this reason, the curing or cross-linking technology by electron beam irradiation has been attracting attention as an environmentally friendly process that does not emit solvent and consumes energy from the viewpoint of the environmental problem that is a global problem. There are many examples that cannot be put to practical use due to the problems described above, the large size of the apparatus, the high initial investment, and the high running cost due to the use of inert gas (nitrogen).

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in consideration of the above circumstances, and has an active energy ray irradiation capable of reducing adverse effects on a working environment and reducing a degree of inerting by inert gas. It is an object to provide a method and an active energy irradiation.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention firstly provides a method in which the oxygen concentration in the electron beam irradiation section is substantially reduced when the acceleration voltage of the electron beam to be irradiated is 40 kV or less. If the oxygen concentration in the air is lower than or equal to the oxygen concentration, and the acceleration voltage of the electron beam to be irradiated exceeds 40 kV, the acceleration voltage (k
When V) is X, and when the oxygen concentration (%) of the electron beam irradiated portion is Y, the irradiation target is irradiated with an electron beam so that the oxygen concentration is represented by the formula (a). A method of irradiating a line is provided.

Y ≦ 1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) (a) Secondly, the oxygen concentration of the electron beam irradiating part is determined by the acceleration voltage of the electron beam to be irradiated. Is less than or equal to 40 kV, the acceleration voltage (kV) is X if the acceleration voltage of the electron beam to be irradiated exceeds 40 kV, and the oxygen concentration (% The present invention provides an active energy ray irradiation method characterized in that an irradiation target is irradiated with an electron beam so that the oxygen concentration represented by the equation (b) is obtained when Y is Y.

1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) ≧ Y ≧ 0.05 (b) Thirdly, in any of the above methods, when the acceleration voltage is 15
An active energy ray irradiation method characterized by being at 0 kV or less.

Fourth, there is provided an active energy ray irradiation method characterized by irradiating an object to be irradiated with ultraviolet rays in air and then irradiating an electron beam. Fifth, there is provided an active energy ray irradiation method characterized by irradiating an object to be irradiated with an electron beam having an acceleration voltage of 40 kV or less in air and then irradiating an ultraviolet ray.

Sixth, an active energy beam irradiation method characterized in that an object to be irradiated is irradiated with an electron beam at an acceleration voltage of 40 kV or less in air, and then irradiated with an electron beam at a higher acceleration voltage. I will provide a.

Seventh, an active energy beam irradiating method characterized in that an object to be irradiated is irradiated with an electron beam at an acceleration voltage of 30 kV or less in air, and then irradiated with an electron beam at a higher acceleration voltage. I will provide a.

Eighth, in any one of the above methods, the object to be irradiated is constituted by forming a coating material on a base material, and the coating material is cured or cross-linked by the irradiation of the electron beam. A method for irradiating active energy is provided. Ninth, there is provided an active energy ray-irradiated product obtained by irradiating with an electron beam by any one of the methods described above.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. FIG. 1 is a schematic view showing an electron beam irradiation apparatus for carrying out the present invention. The apparatus comprises a cylindrical vacuum vessel 1 made of glass or ceramic, an electron beam generating section 2 provided in the vessel 1 for taking out electrons emitted from a cathode as electron beams and accelerating them, An electron beam emitting unit 3 that is provided at an end of the container 1 and emits an electron beam, and has a pin unit 4 for supplying power from a power supply unit (not shown). The electron beam emitting section 3 is provided with a thin-film irradiation window 5. The irradiation window 5 of the electron beam emitting unit 3 has a function of transmitting an electron beam without transmitting a gas, and has a flat shape as shown in FIG. Then, an electron beam emitted from the irradiation window 5 is irradiated on the irradiation object arranged in the irradiation room.

An apparatus having such a configuration is disclosed in US Pat. No. 5,414,267, and is described in American I.
Min by nternational Technologies (AIT)
-Considered as an EB device. In this device, even at a low accelerating voltage, the reduction in the electron beam transmission power is small, and the electron beam can be extracted effectively. This makes it possible to cause the electron beam to act on the coating material on the base material at a low depth, thereby reducing the adverse effect on the base material and the amount of generation of secondary electron beams, resulting in a large shield. Becomes unnecessary.

Electron beam irradiation at a low accelerating voltage can significantly reduce the effect of excitation on oxygen molecules and reduce reaction inhibition on the surface of the coating material due to oxygen radicals. Therefore, there is a possibility that the degree of inerting by nitrogen gas or the like may be reduced as compared with the conventional case.

Therefore, the present inventors have conducted intensive studies on the acceleration voltage of the electron beam to be irradiated and the allowable oxygen concentration in the low acceleration voltage region. As a result, the acceleration voltage becomes 4
Above 0 kV, when the acceleration voltage (kV) is X and the oxygen concentration (%) of the electron beam irradiated portion is Y, the following (a)
It has been found that when the irradiation target is irradiated with an electron beam so as to have the oxygen concentration represented by the formula, reaction inhibition on the surface of the coating agent due to oxygen radicals does not occur, and a predetermined curing performance can be obtained.

Y ≦ 1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) (a) In the case of irradiation of 40 KV or less, the oxygen concentration is 20%
It was found that electron beam irradiation was possible before and after, that is, without inerting.

Therefore, in the present invention, the acceleration voltage is 40
In the case of kV or less, electron beam irradiation is performed at an oxygen concentration substantially in the air or a concentration lower than that.
Assuming that the acceleration voltage is X and the oxygen concentration of the electron beam irradiated portion is Y, the irradiation target is irradiated with the electron beam so as to have the oxygen concentration represented by the above equation (a).

In consideration of the inhibition of the reaction on the surface of the coating agent caused by oxygen radicals, there is no lower limit of the oxygen concentration.
From the viewpoint of the running cost due to nitrogen substitution, it is preferable that the value be within the range of the following expression (b).

1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) ≧ Y ≧ 0.05 (b) When the acceleration voltage is low as described above, the amount of ozone generated at the same time Has also been found to be significantly reduced.

Irradiating an electron beam in the air without inerting has advantages such as lowering running costs. In the present invention, in consideration of this, in order to prevent polymerization inhibition due to oxygen radicals that are problematic in the electron beam irradiation in the air, first, the object to be irradiated is irradiated with ultraviolet light to cure only the surface layer portion, Thereafter, electron beam irradiation is performed. Thereby, polymerization inhibition by oxygen does not occur,
A more complete cured product can be obtained.

In the air, the object to be irradiated has an acceleration voltage of 4
By irradiating an electron beam of 0 kV or less and then irradiating an ultraviolet ray, similarly, polymerization inhibition by oxygen does not occur, and a more complete cured product can be obtained.

Further, the same effect can be obtained by irradiating an object to be irradiated with an electron beam having an acceleration voltage of 40 kV or less in the air and then irradiating the object with an electron beam at a higher acceleration voltage. In this case, the acceleration voltage is initially 30
It is more preferable to perform the electron beam irradiation at a higher acceleration voltage after the electron beam irradiation of kV or less.

A typical embodiment of the present invention is shown in FIG.
As shown in FIG. 1, the electron beam irradiation apparatus 1 having the above-described configuration
A plurality of zeros are combined to form an array 11. In an irradiation chamber 12 below the array 11, an irradiation target 13 transported at a predetermined speed is applied to each of the electron beam irradiation devices 10 constituting the array 11 from an electron beam irradiation device 10. There is a method of irradiating a line.
In the drawings, reference numeral 14 denotes an X-ray shield, and 15 denotes a conveyor shield.

The object to be irradiated in the present invention includes those formed by coating a base material with a coating agent or the like. The base material to which the coating agent is applied may be printing paper, treated or untreated, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, nylon, vinyl chloride, vinylidene chloride, and metals such as aluminum and steel. Cans and drawn metal cans coated with a polyester film.

Examples of applicable coating agents include printing inks,
Paints and adhesives. Among them, examples of the printing ink include ultraviolet and electron beam curable inks such as letterpress ink, offset ink, gravure ink, flexo ink, and screen ink.

Examples of the paint include resins such as acrylic resin, epoxy resin, urethane resin and polyester resin, and ultraviolet or electron beam curable paints using various photosensitive monomers.

Further, as the adhesive, a vinyl polymerization type (cyanoacrylate type, diacrylate type, unsaturated polyester resin type), a condensation type (phenol resin type, urea resin type, melamine resin type), a polyaddition type (epoxy type) Reaction-curing type (monomer type, resin type, urethane resin type)
Oligomer-type) adhesives. As an application example of the adhesive, in addition to a conventional one, it can be applied to a substrate which is weak to heat, such as adhesion of a lens and adhesion of a glass sheet.

In the coating agent according to the present invention, various additives conventionally used can be used.
Examples of various additives include pigments, dyes, stabilizers, solvents,
Preservatives, lubricants, activators and the like.

[0034]

Embodiments of the present invention will be described below. In the following description, "parts" and "%" are parts by weight and% by weight, respectively. Here, an example in which an offset ink is used as the curable coating composition will be described. The adjustment of the offset ink was performed in the following procedure.

[Preparation of varnish] Dipentaerythritol hexaacrylate 69.9%, hydroquinone 0.1
%, And the temperature was raised to 100 ° C. Thereafter, 30 parts of DT150 (a diallyl phthalate resin manufactured by Toto Kasei) was gradually charged and extracted at the time of dissolution. At this time, the viscosity is 210
It was 0 poise (25 ° C.).

[Adjustment of Printing Ink] An ink for offset printing was mixed according to the following formulation and dispersed with three rolls.

Indigo pigment (LIONOL BLUE FG7330) 15 parts The above varnish 50 parts Dipentaerythritol hexaacrylate 25 parts Pentaerythritol tetraacrylate 10 parts (A simple printer).

After printing, EB irradiation was performed using an AIT Min-EB apparatus capable of variably adjusting the acceleration voltage in units of 1 kV. Irradiation condition is acceleration voltage 40 ~ 150K
V, current value 600μA, conveyor speed 10m / mi
n. Inerting was performed using nitrogen. The oxygen concentration was changed by adjusting the nitrogen flow rate. At this time, the oxygen concentration was measured using an oxygen concentration meter (zirconia type LC-750H manufactured by Toray Engineering).

After the irradiation, the curability was evaluated on the basis of the dryness with a touch finger and the adhesion by peeling off a cellophane tape. The evaluation criteria were as follows. Drying property: (completely cured) 5 to 1 (uncured) Adhesion: (good) 5 to 1 (poor) The results obtained are shown in Table 1.

[0040]

[Table 1]

Based on the results, the range of oxygen concentration at which good curability was obtained was determined for each acceleration voltage. FIG. 4 shows the results. As shown in this figure, the acceleration voltage is 40 KV.
In the above description, assuming that the acceleration voltage (kV) is X and the oxygen concentration (%) of the electron beam irradiated portion is Y, the oxygen concentration Y is a region below the straight line shown by the equation (1) in the drawing, that is, (a) It has been confirmed that it is effective to irradiate an irradiation target (a coating provided on a base material) with an electron beam in the region of the formula (1).

Y ≦ 1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) (a) In consideration of economy and the like, equations (1) and (2) in FIG. , That is, the region of the formula (b) was confirmed to be more preferable. 1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) ≧ Y ≧ 0.05 (b)

[0043]

As described above, according to the present invention,
Provided are an active energy ray irradiation method and an active energy irradiated object, which have a small adverse effect on a working environment and can reduce the degree of inertization by an inert gas.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an electron beam irradiation apparatus for carrying out the present invention.

FIG. 2 is a view showing an electron beam emitting unit of the apparatus shown in FIG.

FIG. 3 is a diagram for explaining one embodiment when implementing the present invention.

FIG. 4 is a diagram showing a relationship between an acceleration voltage and an allowable oxygen concentration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Electron beam generation part 3 ... Electron beam emission part 4 ... Pin part 5 ... Irradiation window 10 ... Electron beam irradiation device 11 ... Array 12 ... Irradiation room 13 ... Irradiation Body 14 X-ray shield 15 Conveyor shield

Claims (9)

[Claims] When the acceleration voltage of an electron beam to be irradiated is 40 kV or less,
When the oxygen concentration in the air is substantially equal to or less than the air concentration, and the acceleration voltage of the electron beam to be irradiated exceeds 40 kV, the acceleration voltage (kV) is X, and the oxygen concentration (%) of the electron beam irradiated portion is
, And irradiating the irradiated object with an electron beam so that the oxygen concentration is represented by the formula (a). Y ≦ 1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) (a) 2. When the oxygen concentration of the electron beam irradiator is less than 40 kV,
When the oxygen concentration in the air is substantially equal to or less than the air concentration, and the acceleration voltage of the electron beam to be irradiated exceeds 40 kV, the acceleration voltage (kV) is X, and the oxygen concentration (%) of the electron beam irradiated portion is
, And irradiating the irradiation target with an electron beam so that the oxygen concentration is represented by the formula (b). 1.19 × 10 ² × exp (−4.45 × 10 ⁻² × X) ≧ Y ≧ 0.05 (b) 3. The active energy ray irradiation method according to claim 1, wherein the acceleration voltage is 150 kV or less. 4. An active energy ray irradiation method comprising irradiating an object to be irradiated with ultraviolet rays in air and then irradiating an electron beam. 5. An acceleration voltage of 40 k is applied to an object to be irradiated in air.
An active energy ray irradiation method, comprising irradiating an electron beam of not more than V and then irradiating ultraviolet rays. 6. An acceleration voltage of 40 k is applied to an object to be irradiated in air.
A method for irradiating an active energy ray, comprising irradiating an electron beam of V or less, and then irradiating the electron beam with a higher acceleration voltage. 7. An object to be irradiated has an acceleration voltage of 30 k in air.
7. The active energy beam irradiation method according to claim 6, wherein after the electron beam irradiation of V or less is performed, the electron beam irradiation is performed at a higher acceleration voltage. 8. The object to be irradiated, wherein a coating material is formed on a base material, and the coating material is cured or cross-linked by the irradiation of the electron beam. 8. The active energy irradiation method according to 7. 9. An active energy ray-irradiated substance obtained by irradiating an electron beam by the method according to any one of claims 1 to 8.