JPH04341374A - Method for irradiation with ultraviolet rays - Google Patents

Abstract

PURPOSE:To always uniformly irradiate an object to be coated with ultraviolet rays regardless of the shape and size of the object to be coated by devising the arranging positions of a plurality of lamps and freely changing over the outputs of the lamps, when the ultraviolet curable coating solution applied to the object to be coated is irradiated with ultraviolet rays to be cured. CONSTITUTION:A plurality of lamps 2 are arranged so that each of the axial lines of the light emitting tubes of the lamps 2 and the advance direction of an object to be coated form a predetermined angle theta excepting a right angle, pref., an angle of 45 deg. or less and the outputs per unit length of the lamps 2 are made possible to be changed over to at least two stages. The lamps 2 each of which is constituted of a light emitting pipe 21 and a reflecting mirror 22 are arranged in a tunnel shape and the number of the lamps 2 and the change-over of the lamps 2 are determined corresponding to necessary irradiation energy and the shape and size of the object 1 to be coated. When the angle theta of inclination is provided, luminous intensities hourly change at the respective points A, B, C on the surface of the object 1 to be coated and integrated energy is uniformized as a whole.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for curing an ultraviolet curable coating liquid (hereinafter referred to as a coating liquid) applied to an object to be painted, and more specifically to a method for curing an ultraviolet curable coating liquid (hereinafter referred to as a coating liquid) applied to an object to be painted. The present invention relates to a method for uniformly irradiating ultraviolet rays onto a painted coating solution.

0002

[Prior Art] Generally, in order to irradiate a coating liquid applied to an object to be coated with ultraviolet rays, when the object to be coated has a flat shape, a lamp 2 is emitted as shown in Fig. 4(a). tube 21
are arranged so that their axes are perpendicular to the traveling direction of the object 1 to be coated, and the required number of beams are lined up and irradiated. A commonly used lamp 2 consists of an arc tube 21 and a reflector 22, and the total output (W) of the arc tube 21 is determined by the arc tube length (cm) x output per unit length (W/cm). . On the other hand, reflector 2
Although the reflection characteristics, that is, the light distribution characteristics of the mirror 2 differ depending on its shape, generally, a reflecting mirror 22 whose cross-sectional shape is a parabola, an ellipse, or a similar shape is widely used.

If a parabolic section is used and the arc tube 21 is placed at the focus of the parabola, ideally (that is, the diameter of the arc tube = 0)
) parallel light can be irradiated. On the other hand, in the case of an elliptical cross section, if the arc tube 21 is placed at the first focal point, the reflected light ideally has the property of condensing at the second focal point. but,
In either case, the size of the arc tube 21 is finite and is not so small that it can be ignored compared to the size of the reflecting mirror, so an ideal light distribution cannot be obtained; In order to increase the utilization efficiency of the light emitted from the tube 21, in most cases, the design is such that the light is concentrated and distributed.

As an example, a light distribution diagram is shown in FIG. As can be understood from the figure, the illuminance is highest directly below the arc tube 21, and rapidly decreases as it moves away from directly below. Furthermore, as is clear from FIGS. 12A, 20B, and 2C, as the distance to the irradiation surface increases, the maximum irradiance becomes smaller and the light distribution becomes smoother.

[0005]

[Problem to be Solved by the Invention] Therefore, when irradiating ultraviolet rays onto a three-dimensional object 1 using the above-mentioned general lamp, the same concept as the arrangement shown in FIG. 4(a) should be used. , simply arranging the lamp 2 perpendicular to the traveling direction of the object 1 to be painted as shown in FIG. ) will be partially different, and uniform irradiation will not be possible, especially on the sides. On the other hand, even if the arrangement of the lamp 2 is changed by 90 degrees as shown in FIG. 4(c), the light distribution of the light emitted from the lamp 2 will be roughly as shown in FIG. Since it is not flat, uniform irradiation cannot be performed as in the case of FIG. 4(b).

Furthermore, when the irradiation distance is constant and the shape and size of the object 1 to be coated changes, the irradiation distance will change in both cases of FIGS. 4(b) and 4(c) from the above-mentioned light distribution state. Since the irradiation distance deviates from the preset best irradiation distance and becomes inappropriate, either excessive energy supply (overcure) or insufficient energy (undercure) will result. As a countermeasure when the shape and size of the object 1 to be coated changes, what has traditionally been done is to make it possible to change the irradiation distance and position of each lamp individually or to some extent collectively using a motor, etc. The lamp arrangement is changed every time the object 1 to be coated changes, but if the object 1 to be coated is changed frequently, there is a problem with followability, and the lamp drive mechanism is exposed to ultraviolet rays and high-temperature atmospheres. This method has problems such as the problem that the lamp 2 is placed in a fixed position, and that the device is more expensive than a method in which the lamp 2 is fixedly installed.

The present invention solves the above problems and enables uniform irradiation of not only flat objects but also three-dimensional objects with ultraviolet rays using relatively inexpensive equipment. The purpose is to provide an irradiation method.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the gist of the present invention is to provide a method for curing an ultraviolet curable coating liquid applied to an object by irradiating it with ultraviolet rays. Install the lamp so that the axis of the lamp and the direction of movement of the object to be coated form a predetermined angle other than a right angle, and set the output per unit length of the lamp to at least 2.
This ultraviolet irradiation method is characterized in that the entire surface to be coated is uniformly irradiated with ultraviolet rays by changing the lamp output in accordance with the size and shape of the object to be coated. As one of the preferred embodiments,
There is a method in which a plurality of lamps are arranged in a tunnel shape when viewed from the direction in which the object to be coated is traveling.

[0009]

[Operation] The illuminance of the painted surface of the object to be painted moves sequentially from time to time on the irradiation distribution curve of the lamp, making it possible to equalize the integrated energy as a whole. Moreover, the total energy in the optimum state can be secured in terms of absolute level, and as a result, energy approximately equal to the integrated energy when passing through an intermediate illuminance level in the irradiation distribution curve is provided over the entire area.

Furthermore, if the shape and size of the object to be coated changes, the absolute level and uniformity may be affected. Adjust the irradiation energy level from the lamp 2, select an appropriate inclination angle θ, and switch the output to maintain the integrated energy level over the entire painting surface for objects of various shapes and sizes. At the same time, achieve uniformity.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to the drawings. Figure 1 shows an embodiment of the ultraviolet irradiation method according to the present invention, in which the lamp is installed so that the arc tube axis of the lamp and the traveling direction of the object to be coated form a certain angle (hereinafter referred to as the inclination angle = θ°). In the figures, (a) is a plan view, and (b) is a front view. FIG. 2 is a flowchart for explaining the procedure for implementing the present invention.

In FIG. 1, 1 is an object to be painted, 2 is a lamp, 21 is an arc tube which is one of the components of the lamp 2, and 22 is a lamp.
also indicates a reflecting mirror. In the figure, the inclination angle θ is greater than 0° and smaller than 90°, but preferably 45°.
The following is good. If the angle exceeds 45°, the state gradually approaches the state shown in FIG. 4(b), which is not preferable. Although the number of lamps 2 is not particularly specified, it should be determined depending on the required irradiation energy and the shape and size of the object to be coated 1, and is generally preferably in the range of 3 to 10 lamps. Figure 3 shows the illuminance distribution curve according to the irradiation distance of a commonly used lamp as mentioned above.The irradiation distribution becomes smoother as the distance increases from L1 → L2 → L3, but the absolute level is almost proportional to the distance. going down.

Similar to the conventional method, when irradiating the object 1 by arranging it in a tunnel with a plurality of lamps 2 parallel to the traveling direction of the object 1 as shown in FIG. 4(c), the irradiation shown in FIG. 3(c) If irradiation is applied by applying distribution, a certain degree of uniformity can be obtained, but the absolute level is insufficient. On the other hand, if the irradiation distribution shown in FIG. 3(b) is applied, point C (
In Figure 1), the exposure is at point c, which has high illuminance from beginning to end, so a high integrated energy (= illuminance x time) can be obtained.
At points B to A, only the integrated energy corresponding to points b and a, which have medium to low illumination levels, is obtained, resulting in lack of uniformity.

However, if the inclination angle θ is provided as in the present invention, the illuminance of each of the points A, B, and C, which is the painting surface of the object 1, changes moment by moment on the curve shown in FIG. 3(b). , for example a
→It moves as shown in b, and the integrated energy can be equalized as a whole. In addition, as an absolute level, the total energy in the state shown in Figure 3(b) can be secured, so as a result, the irradiation energy is approximately equal to the cumulative energy when passing through the intermediate illuminance level shown in Figure 3(b) over the entire area. You will be able to get it for a long time.

However, if the shape and size of the object 1 to be coated changes, the absolute level and uniformity may be affected. By switching, the irradiation energy level from the lamp 2 is adjusted, and by combining both the inclination angle θ and the output switching, it is possible to integrate the entire coating surface for any object 1 of various shapes and sizes. It is necessary to maintain energy levels and achieve uniformity.

To explain the flow of the control method using FIG. 2, first, the common number and arrangement of lamps are determined based on the shape and size of the object 1 to be coated, and then the concept of the present invention is applied. Therefore, measure in advance and set an appropriate inclination angle θ.

After that, when actually processing the object 1 to be coated, for example, if a signal is sent via a control device (not shown) and the outputs per unit length of each lamp 2, 2, . . . are switched electrically, the current The most suitable irradiation can be applied to the object 1 being treated. Various methods can be considered to determine the type of object 1 to be painted, and there are no particular regulations, but the most primitive method is manual input by humans to non-contact recognition of the shape of the actual object using a CCD camera or the like. Any advanced method that can be performed with current technology can be applied to the present invention.

[0018]

Effects of the Invention As explained above, according to the present invention, there is no need for an expensive drive device to move the lamp, and even if the lamp is in a fixed arrangement, it can be used to paint objects of various shapes and sizes. In either case, it is possible to maintain and equalize the appropriate integrated energy over the entire painted surface, which is extremely useful from an industrial perspective.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the ultraviolet irradiation method according to the present invention.

FIG. 2 is a flowchart illustrating a procedure for implementing the present invention.

FIG. 3 is a distribution diagram showing the light distribution characteristics of commonly used lamps.

FIG. 4 is an explanatory diagram showing a conventional ultraviolet irradiation method.

[Explanation of symbols]

1 Object to be painted 2 Lamp 21 Arc tube 22 Reflector θ　　　　　　　　　　Inclination angle

Claims (2)

[Claims] Claim 1: A method of curing an ultraviolet curable coating liquid applied to an object to be painted by irradiating it with ultraviolet rays, in which a plurality of lamps are used, except that the arc tube axes of the lamps and the direction of movement of the object to be painted are perpendicular to each other. In addition to installing the lamp at a predetermined angle, the output per unit length of the lamp can be switched in at least two stages, and the output of the lamp can be switched according to the size and shape of the object to be painted, and the entire surface to be painted can be coated. An ultraviolet irradiation method characterized by irradiating uniform ultraviolet rays to [Claim 2] Claim 1, wherein the plurality of lamps are arranged in a tunnel shape when viewed from the traveling direction of the object to be coated.
Ultraviolet irradiation method described.