Ultraviolet light irradiation method, and ultraviolet light irradiation device

Abstract

To efficiently cure an object.SOLUTION: An ultraviolet light irradiation method incudes a first irradiation step of irradiating an object with first ultraviolet light at a peak wavelength of 360 nm or more and 410 nm or less and irradiance of 288 mW / cm2 or more for irradiation time of 2.5 seconds or more, and a second irradiation step of irradiating the object with second ultraviolet light at a peak wavelength of 260 nm or more and 290 nm or less and irradiance of 10.5 mW / cm2 or more for irradiation time of 2.5 seconds or more, after the first irradiation step, and cures the object having a thickness of 10 μm or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for irradiating ultraviolet light and an ultraviolet light irradiation device.

Background Art

[0002] For example, Patent Document 1 discloses an ultraviolet light irradiation method for curing an object by first irradiating only ultraviolet light having a peak wavelength of 365 nm and then irradiating only ultraviolet light having a peak wavelength of 240 nm (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An embodiment of the present disclosure aims to efficiently cure an object.

Means for Solving the Problems

[0005] The ultraviolet light irradiation method according to an embodiment of the present disclosure includes a first irradiation step of irradiating an object with first ultraviolet light having a peak wavelength of 360 nm or more and 410 nm or less, an irradiance of 288 mW / cm 2 or more, and an irradiation time of 2.5 seconds or more, and a second irradiation step of irradiating the object with second ultraviolet light having a peak wavelength of 260 nm or more and 290 nm or less, an irradiance of 10.5 mW / cm 2 or more, and an irradiation time of 2.5 seconds or more, and cures an object having a thickness of 10 μm or more.

Effects of the Invention

[0006] According to an embodiment of the present disclosure, an object can be efficiently cured.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] The ultraviolet light irradiation method and the ultraviolet light irradiation device according to the embodiments of the present disclosure will be described in detail with reference to the drawings. However, the embodiments shown below are examples of the ultraviolet light irradiation method and the ultraviolet light irradiation device for embodying the technical idea of the present embodiment, and are not limited thereto. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of the present disclosure only to a specific form unless there is a description to that effect, but are merely illustrative examples. Note that the sizes, positional relationships, etc. of the members shown in each drawing may be exaggerated for clarity of explanation. In the following description, the same names and reference numerals indicate the same or similar members, and detailed descriptions will be omitted as appropriate.

[0009] Also, in the following description, terms indicating a specific direction or position (for example, "up", "down" and other terms including these terms) may be used. These terms are used only for making the relative positions, orientations, directions, etc. in the referenced drawings easier to understand, and do not have to match the relationships during the use of the light emitting device according to the embodiment. Also, these directions are independent of the direction of gravity. In the terms of this specification, the depth direction can also be referred to as the thickness direction of the object.

[0010] [First Embodiment] <Configuration of the Ultraviolet Light Irradiation Device According to the First Embodiment> FIG. 1 is a schematic side view showing an example of an ultraviolet light irradiation device 100 according to the first embodiment. In FIG. 1, a part of each of the first ultraviolet light U1 and the second ultraviolet light U2 irradiated from the irradiation unit 1 is indicated by a thick arrow. However, the thick arrows indicating the first ultraviolet light U1 and the second ultraviolet light U2 show that the irradiation unit 1 can irradiate each of the first ultraviolet light U1 and the second ultraviolet light U2, and do not mean that the irradiation unit 1 irradiates the first ultraviolet light U1 and the second ultraviolet light U2 in parallel.

[0011] As shown in FIG. 1, the ultraviolet light irradiation device 100 has an irradiation unit 1 including a first irradiation unit 11 and a second irradiation unit 12. The irradiation unit 1 includes a first irradiation unit 11 that irradiates first ultraviolet light U1 having a peak wavelength of 360 nm or more and 410 nm or less. The first ultraviolet light U1 irradiated by the first irradiation unit 11 is irradiated onto the object S. The irradiation unit 1 also includes a second irradiation unit 12 that irradiates second ultraviolet light U2 having a peak wavelength of 260 nm or more and 290 nm or less. The second ultraviolet light U2 irradiated by the second irradiation unit 12 is irradiated onto the object S. In the example shown in FIG. 1, the ultraviolet light irradiation device 100 has a housing 2 in which the first irradiation unit 11 and the second irradiation unit 12 are arranged, and a control unit 3 that controls the irradiation of the ultraviolet light U from the irradiation unit 1 onto the object S. The ultraviolet light irradiation device 100 irradiates the object S with the first ultraviolet light U1 at an irradiance of 288 mW / cm 2 or more and an irradiation time of 2.5 seconds or more. Also, the ultraviolet light irradiation device 100 irradiates the object S with the second ultraviolet light U2 at an irradiance of 10.5 mW / cm 2 or more and an irradiation time of 2.5 seconds or more.

[0012] In the example shown in FIG. 1, the object S is a paint applied to the upper surface of the base material T. However, the object S is not limited to the paint, and may be an object other than the paint such as ink, adhesive, or coating agent as long as it is cured by being irradiated with the ultraviolet light U.

[0013] In the example shown in FIG. 1, the first irradiation unit 11 irradiates the first ultraviolet light U1 downward. The first ultraviolet light U1 is irradiated onto the object S from a position that is at an irradiation distance D away from the object S above the object S. The second irradiation unit 12 irradiates the second ultraviolet light U2 downward. The second ultraviolet light U2 is irradiated onto the object S from a position that is at an irradiation distance D away from the object S above the object S. For example, the first irradiation unit 11 and the second irradiation unit 12 are arranged at positions that are separated upward by a predetermined distance from the transport mechanism, and by transporting a transported object having a specific thickness (for example, an object in which the object S is provided on the base material T) by the transport mechanism, the object S located at a position that is at an irradiation distance D away from the object S can be irradiated with ultraviolet light. By transporting the base material T to the irradiation regions of the first ultraviolet light U1 and the second ultraviolet light U2, the object S provided on the upper surface of the base material is irradiated with the first ultraviolet light U1 and the second ultraviolet light U2. For example, after the first irradiation unit 11 irradiates the first ultraviolet light U1 onto the object S, the second irradiation unit 12 can irradiate the second ultraviolet light U2 onto the portion of the object S that has been irradiated with the first ultraviolet light U1. Note that the thickness of the transported object does not necessarily have to be a fixed thickness, and for example, the positions of the first irradiation unit 11 and the second irradiation unit 12 may be adjusted according to the thickness of the transported object. Also, if the change in the thickness of the transported object is sufficiently small, it is also possible to perform the same processing on transported objects having different thicknesses.

[0014] The first irradiation unit 11 may include a first lens that transmits the first ultraviolet light U1 irradiated onto the object S. The second irradiation unit 12 may include a second lens that transmits the second ultraviolet light U2 irradiated onto the object S. The irradiation distance D from the end of the first lens or the second lens on the object S side to the object S can also be referred to as the working distance.

[0015] In the example shown in FIG. 1, the base material T is conveyed in the conveying direction A indicated by the arrow by a conveying mechanism such as a conveyor. The ultraviolet light irradiation device 100 can irradiate the object S provided on the upper surface of the base material T conveyed in the conveying direction A with the first ultraviolet light U1 and the second ultraviolet light U2 from above. However, the ultraviolet light irradiation device 100 is not limited to irradiating the conveyed base material T with the ultraviolet light U, and may irradiate the object S on the stationary base material T with the ultraviolet light U. Further, the ultraviolet light irradiation device 100 may move the irradiation unit 1 to the stationary or conveyed base material T to irradiate the ultraviolet light U. Further, the irradiation of the ultraviolet light U by the ultraviolet light irradiation device 100 is not limited to irradiating the object S provided on the upper surface of the base material T from above, and may irradiate the object S provided on the lower surface of the base material T from below, or may irradiate the object S provided on the side surface of the base material T from the side.

[0016] For example, light emitting diodes (LEDs) can be used for the first irradiation unit 11 and the second irradiation unit 12. The first irradiation unit 11 and the second irradiation unit 12 can each include one or more light emitting diodes. When the first irradiation unit 11 includes a plurality of light emitting diodes, it is preferable that the plurality of light emitting diodes are of the same material. When the second irradiation unit 12 includes a plurality of light emitting diodes, it is preferable that the plurality of light emitting diodes are of the same material.

[0017] The control unit 3 can control the irradiance of each of the first irradiation unit 11 and the second irradiation unit 12 by controlling the current value of the drive current supplied to each of the first irradiation unit 11 and the second irradiation unit 12. Further, the control unit 3 can control the irradiation time of each of the first irradiation unit 11 and the second irradiation unit 12 by controlling the timing of supplying or stopping the supply of the drive current to each of the first irradiation unit 11 and the second irradiation unit 12. The control unit 3 can be configured to include at least one of a CPU (Central Processing Unit), an electric circuit, or an electronic circuit.

[0018] <Method for irradiating ultraviolet light U according to the first embodiment> The ultraviolet light U irradiation method according to this embodiment has a peak wavelength of 360 nm or more and 410 nm or less, an irradiance of 288 mW / cm 2 or more, and includes a first irradiation step of irradiating the object S with the first ultraviolet light U1 for an irradiation time of 2.5 seconds or more. Further, the ultraviolet light U irradiation method according to this embodiment, after the first irradiation step, has a peak wavelength of 260 nm or more and 290 nm or less, and an irradiance of 10.5 mW / cm 2 or more, and includes a second irradiation step of irradiating the object S with the second ultraviolet light U2 for an irradiation time of 2.5 seconds or more. The ultraviolet light U irradiation method according to this embodiment cures the object S having a thickness of 10 μm or more.

[0019] For example, ultraviolet light with a long peak wavelength easily penetrates the surface of the object S, is absorbed after reaching deep inside. On the other hand, ultraviolet light with a short peak wavelength, after penetrating the surface of the object S, does not reach deep inside and is easily absorbed on the surface of the paint. Therefore, when irradiating the object S with ultraviolet light having a long peak wavelength and ultraviolet light having a short peak wavelength simultaneously, the vicinity of the surface of the object S hardens, and the hardened portion inhibits the progress of the ultraviolet light, so that the ultraviolet light may not reach deep inside the object S. Also, when irradiating the object S with ultraviolet light having a short peak wavelength and then irradiating with ultraviolet light having a long peak wavelength, the vicinity of the surface of the object S hardens first, and the hardened portion of the object S inhibits the progress of the ultraviolet light having a long peak wavelength, so that the ultraviolet light having a long peak wavelength may not reach deep inside the object S. If the ultraviolet light does not reach deep inside the object S, there is a possibility that the object S cannot be sufficiently cured.

[0020] Also, Patent Document 1 discloses a method of curing an object by first irradiating only ultraviolet light having a peak wavelength of 365 nm and then irradiating only ultraviolet light having a peak wavelength of 240 nm as an ultraviolet light irradiation method for curing an object. However, the object to be cured by the method disclosed here is an object having a thickness on the order of several μm, and does not sufficiently target an object having a thickness of 10 μm or more. This is presumably because, at the time of filing Patent Document 1, the method disclosed in Patent Document 1 was a method that could not obtain sufficient curing for an object having a large thickness.

[0021] Under such circumstances, at the time of filing the present application, a method for efficiently curing an object with a thickness of 10 μm or more has not been established, and the objects for which the curing treatment of the object by ultraviolet irradiation can be effectively used have been limited. In view of such a situation, rather than simply irradiating light with a peak wavelength of 360 nm or more and 410 nm or less and light with a peak wavelength of 260 nm or more and 290 nm or less, by controlling the irradiation of these lights with an appropriate irradiance and irradiation time, the present disclosure has value in that a method for efficiently curing an object with a thickness of 10 μm or more has been found.

[0022] In the present embodiment, the second irradiation unit 12 irradiates the object S with the second ultraviolet light U2 after the first irradiation unit 11 irradiates the object S with the first ultraviolet light U1. Thereby, after curing the deep part of the object S by irradiating the first ultraviolet light U1 that easily reaches the deep part of the object S, the vicinity of the surface of the object S can be cured by irradiating the second ultraviolet light U2 that hardly reaches the deep part of the object S. By sufficiently curing the object S from the surface to the deep part, in the present embodiment, an object S with a thickness of 10 μm or more can be efficiently cured. Note that the peak wavelength of each of the first ultraviolet light U1 and the second ultraviolet light U2 may include a variation in wavelength. For example, the first ultraviolet light U1 with a peak wavelength of 365 nm may include ultraviolet light with a peak wavelength of 360 nm or more and 370 nm or less in consideration of a wavelength variation of about ±5 nm. Further, for example, the second ultraviolet light U2 with a peak wavelength of 280 nm may include ultraviolet light with a peak wavelength of 275 nm or more and 285 nm or less in consideration of a wavelength variation of about ±5 nm.

[0023] In the ultraviolet irradiation device 100, for example, in the range where the conveyance speed of the object S is 1 m / min or more and 100 m / min or less, the irradiance is 288 mW / cm 2 or more, and the irradiation time of the first ultraviolet light U1 is 2.5 seconds or more, and the irradiance is 10.5 mW / cm 2As described above, and by irradiating the second ultraviolet light U2 with an irradiation time of 2.5 seconds or more, the above effect that an object with a thickness of 10 μm or more can be efficiently cured can be obtained.

[0024] In addition, the ultraviolet light irradiation method according to this embodiment can also be considered from the perspective of the integrated light amount of the ultraviolet light U irradiated on the object S. However, capturing only the integrated light amount may include unrealistic technologies, and thus it is not necessarily an appropriate expression of the invention. For example, if the technology is specified only by the integrated light amount, theoretically the irradiation time can be extended indefinitely, resulting in unrealistic and inefficient forms. Therefore, when considering from the integrated light amount, the upper limit of the irradiation time during which the object S is irradiated with the ultraviolet light U should be specified. For example, in the ultraviolet light irradiation device 100, the integrated light amount of the ultraviolet light U irradiated on the object S is 22.1 J / mm 2 or more, and can be configured such that the irradiation time is 100 seconds or less. If the irradiation time can be 100 seconds or less, the curing process can proceed efficiently.

[0025] Also, depending on the irradiation conditions of the ultraviolet light, if only the ultraviolet light with a longer peak wavelength is irradiated first and then the ultraviolet light with a shorter peak wavelength is irradiated, an object with a thickness of 10 μm or more may not be efficiently cured. However, in this embodiment, after irradiating the ultraviolet light with a longer peak wavelength, not only irradiating the ultraviolet light with a shorter peak wavelength, but also the irradiance is 288 mW / cm 2 or more, and after irradiating the object S with the first ultraviolet light U1 with an irradiation time of 2.5 seconds or more, the irradiance is 10.5 mW / cm 2 or more, and the object S is irradiated with the second ultraviolet light U2 with an irradiation time of 2.5 seconds or more. Under such specific irradiation conditions, an object with a thickness of 10 μm or more can be efficiently cured. Regarding the relationship between various irradiation conditions and the curing state, which is the basis for efficiently curing an object with a thickness of 10 μm or more according to the above irradiation conditions, it will be described later with reference to Table 1 and Table 2.

[0026] In the method of irradiating ultraviolet light U by the ultraviolet light irradiation device 100 shown in FIG. 1, each of the first ultraviolet light U1 and the second ultraviolet light U2 is light using a light-emitting diode as a light source. The light-emitting diode is small in size compared with a light source of ultraviolet light such as a mercury lamp. Therefore, by using the light-emitting diode as a light source, in the method of irradiating ultraviolet light U by the ultraviolet light irradiation device 100 shown in FIG. 1, the method of irradiating ultraviolet light U can be executed using the small-sized ultraviolet light irradiation device 100. Further, the light-emitting diode has a narrow half-value width of the emission peak in the emission spectrum compared with a light source of ultraviolet light such as a mercury lamp. The first ultraviolet light U1 does not substantially contain light having a wavelength of 340 nm or less. The second ultraviolet light U2 does not substantially contain light having a wavelength of 310 nm or more. Therefore, by using the light-emitting diode as a light source, when irradiating each of the first ultraviolet light U1 and the second ultraviolet light U2, it is possible to efficiently cure a desired region while avoiding curing of a region different from the desired region in the depth direction of the object S.

[0027] <Example of curing experiment results of object S> An example of the curing experiment results of the object S will be described. The main experimental conditions are shown below. Note that the size of the base material T is the area of the base material T in a direction substantially orthogonal to the depth direction. · Irradiation distance D: 50 mm · Size of base material T: 50 mm × 50 mm · Conveying speed V: 20 mm / s · Average thickness of object S: 80 μm · Peak wavelength of the first irradiation unit 11: 365 nm · Peak wavelength of the second irradiation unit 12: 280 nm

[0028] Table 1 shown below shows an example of the experimental results of the relationship between the irradiance and the curing state of each of the first irradiation unit 11 and the second irradiation unit 12.

[0029]

Table 1

[0030] Table 2 shown below indicates the correspondence between the symbols indicating the cured state in Table 1 and the cured state.

[0031]

Table 2

[0032] In the evaluation of the cured state in Table 2, a stamp with a pattern formed on the object S after applying it to the base material T and irradiating it with ultraviolet light U was placed, a load of 1 kg was applied, and it was left standing for 5 minutes. After standing, the cured state was evaluated from the degree of the stamp pattern remaining on the object S. "◎" indicates a state where there is no remaining trace of the stamp pattern, "〇" indicates a state where a part of the stamp pattern remains, and "×" indicates a state where the stamp pattern clearly remains.

[0033] In Table 1, each of the current value of 1760 mA of the second irradiation unit 12 and the current value of 1320 mA of the second irradiation unit 12 is the sum of the current values of the current supplied to the second irradiation unit 12 in each of the two transports of the object S. The other current values in Table 1 are the current values of the current supplied to the first irradiation unit 11 or the second irradiation unit 12 in one transport of the object S. Also, the irradiance of 28.0 mW / cm 2 of the second irradiation unit 12, and the irradiance of 21.0 mW / cm 2 of each are the sum of the irradiances of the light irradiated from the second irradiation unit 12 in each of the two transports of the object S. The other irradiances are the irradiances of the light irradiated from the first irradiation unit 11 or the second irradiation unit 12 in one transport of the object S. The integrated light amount means the light amount obtained by integrating the light amount of the ultraviolet light U over the irradiation time.

[0034] As shown in Table 1 and Table 2, the irradiance of the first ultraviolet light U1 in the first irradiation step is 384 mW / cm 2 or more, and the irradiance of the second ultraviolet light U2 in the second irradiation step is 14 mW / cm 2When the above conditions were met, the curing state of the object S became "◎". From this result, the irradiance of the first ultraviolet light U1 in the first irradiation step was 384 mW / cm 2 or more, and the irradiance of the second ultraviolet light U2 in the second irradiation step was 14 mW / cm 2 or more, it was found that the object S with a thickness of 10 μm or more could be efficiently cured.

[0035] As shown in Table 1 and Table 2, when the integrated light amount of the ultraviolet light U irradiated on the object S was 22.1 J / mm 2 or more, the curing state of the object S became "◎" or "〇". From this result, it was found that when the integrated light amount of the ultraviolet light U irradiated on the object S was 22 J / mm 2 or more, the object S with a thickness of 10 μm or more could be effectively cured.

[0036] As shown in Table 1 and Table 2, the object S after the second irradiation step had good tackiness. From this result, it was found that the object S after the second irradiation step could efficiently cure the object S with a thickness of 10 μm or more. In this curing experiment, it was also confirmed that when the thickness of the object S was less than 10 μm, if only ultraviolet light with a peak wavelength of 365 nm was irradiated under the conditions that the irradiance was less than 288 mW / cm2 and the irradiation time was less than 2.5 seconds, the tackiness was insufficient.

[0037] [Second Embodiment] Next, the ultraviolet light irradiation device and the ultraviolet light irradiation method according to the second embodiment will be described. Note that the same names and reference numerals as those in the already described embodiments indicate the same or similar members or configurations, and the detailed description will be omitted as appropriate.

[0038] [Configuration of the Ultraviolet Light Irradiation Device According to the Second Embodiment]< FIG. 2 is a schematic side view showing an example of the ultraviolet light irradiation device 100a according to the second embodiment. In FIG. 2, a part of each of the first ultraviolet light U1, the second ultraviolet light U2, and the third ultraviolet light U3 irradiated from the irradiation unit 1 is indicated by a thick arrow. However, the thick arrows indicating the first ultraviolet light U1, the second ultraviolet light U2, and the third ultraviolet light U3 show that the irradiation unit 1 can irradiate each of the first ultraviolet light U1, the second ultraviolet light U2, and the third ultraviolet light U3, and do not mean that the irradiation unit 1 irradiates the first ultraviolet light U1, the second ultraviolet light U2, and the third ultraviolet light U3 in parallel.

[0039] As shown in FIG. 2, the ultraviolet light irradiation device 100a further includes a third irradiation unit 13 that irradiates the object S with the third ultraviolet light U3 having a peak wavelength of 300 nm or more and 350 nm or less, an irradiance of 6 mW / cm 2 or more, and an irradiation time of 2.5 seconds or more. This point is different from the first embodiment described above.

[0040] For example, a light emitting diode can be used for the third irradiation unit 13. When the third irradiation unit 13 uses a light emitting diode as a light source, the third ultraviolet light U3 does not substantially contain light having a wavelength of 280 nm or less and light having a wavelength of 370 nm or more. The third irradiation unit 13 may include one or more light emitting diodes. When the third irradiation unit 13 includes a plurality of light emitting diodes, it is preferable that the plurality of light emitting diodes are made of the same material.

[0041] The control unit 3 can control the irradiance of the third irradiation unit 13 by controlling the current value of the drive current supplied to the third irradiation unit 13. Further, the control unit 3 can control the irradiation time by the third irradiation unit 13 by controlling the timing of supplying or stopping the drive current to the third irradiation unit 13.

[0042] <Method for irradiating ultraviolet light U according to the second embodiment> The method for irradiating the ultraviolet light U according to the present embodiment is such that, after the first irradiation step and before the second irradiation step, the peak wavelength is 300 nm or more and 350 nm or less, and the irradiance is 6 mW / cm 2Furthermore, it further includes a third irradiation step of irradiating the object S with the third ultraviolet light U3 for 2.5 seconds or more. This is the main difference from the first embodiment described above.

[0043] By the method of irradiating the ultraviolet light U according to this embodiment, in the depth direction, the region between the region cured in the first irradiation step and the region cured in the second irradiation step can be preferably cured. Thereby, the uncured region can be reduced, and the object S can be cured efficiently.

[0044] In the method of irradiating the ultraviolet light U by the ultraviolet light irradiation device 100a shown in FIG. 2, the third ultraviolet light U3 is light using a light-emitting diode as a light source. By using a light-emitting diode as a light source, in the method of irradiating the ultraviolet light U by the ultraviolet light irradiation device 100a shown in FIG. 2, the method of irradiating the ultraviolet light U can be executed using a small-sized ultraviolet light irradiation device 100. Further, by using a light-emitting diode as a light source, when irradiating each of the first ultraviolet light U1, the second ultraviolet light U2, and the third ultraviolet light U3, while avoiding curing of a region different from the desired region in the depth direction of the object S, the desired region can be cured efficiently.

[0045] Although the preferred embodiments have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope described in the claims.

[0046] The numbers such as ordinal numbers and quantities used in the description of the embodiments are all exemplified for specifically explaining the technology of the present disclosure, and the present disclosure is not limited to the exemplified numbers. Also, the connection relationship between the components is exemplified for specifically explaining the technology of the present disclosure, and the connection relationship for realizing the functions of the present disclosure is not limited thereto.

[0047] The ultraviolet light irradiation method of the present disclosure can efficiently cure an object, and thus can be suitably used in applications such as painting, coating, printing, and exposure for irradiating the object with ultraviolet light to cure the object. From the viewpoint of efficiently curing an object with a thickness of 10 μm or more, it is particularly suitable for painting applications of vehicles such as automobiles. However, the ultraviolet light irradiation method of the present disclosure is not limited to these applications.

[0048] Aspects of the present disclosure are as follows, for example. <Item 1> A first irradiation step of irradiating an object with a first ultraviolet light having a peak wavelength of 360 nm or more and 410 nm or less, an irradiance of 288 mW / cm2 or more, and an irradiation time of 2.5 seconds or more; and after the first irradiation step, a peak wavelength of 260 nm or more and 290 nm or less, an irradiance of 10.5 mW / cm2 or more, and an irradiation time of 2.5 seconds or more A second irradiation step of irradiating the object with a second ultraviolet light, and an ultraviolet light irradiation method for curing the object having a thickness of 10 μm or more. <Item 2> The irradiance of the first ultraviolet light in the first irradiation step is 384 mW / cm2 or more, and the irradiance of the second ultraviolet light in the second irradiation step is 14 mW / cm2 or more. The ultraviolet light irradiation method according to <Item 1>. <Item 3> Further including a third irradiation step of irradiating the object with a third ultraviolet light having a peak wavelength of 300 nm or more and 350 nm or less, an irradiance of 6 mW / cm2 or more, and an irradiation time of 2.5 seconds or more after the first irradiation step and before the second irradiation step. The ultraviolet light irradiation method according to <Item 1> or <Item 2>. <Item 4> The integrated light amount of the ultraviolet light irradiated on the object is 22.1 J / mm2 or more. The ultraviolet light irradiation method according to any one of <Item 1> to <Item 3>. <Item 5> The object after performing the second irradiation step has good tackiness. The ultraviolet light irradiation method according to any one of <Item 1> to <Item 4>. <Item 6> The ultraviolet light is light using a light emitting diode as a light source. The ultraviolet light irradiation method according to any one of <Item 1> to <Item 5>. <Item 7> An ultraviolet light irradiation device comprising an irradiation unit that executes the ultraviolet light irradiation method according to any one of <Item 1> to <Item 6>.

Explanation of Signs

[0049] 1, 1a Irradiation unit 11 First irradiation unit 12 Second irradiation unit 13 Third irradiation unit 2 Housing 3 Control unit 100, 100a Ultraviolet light irradiation device A Conveying direction D Irradiation distance S Object T Substrate U Ultraviolet light U1 First ultraviolet light U2 Second ultraviolet light U3 Third ultraviolet light

Claims

1. The peak wavelength is 360 nm or more and 410 nm or less, and the irradiance is 288 mW / cm ２ or more, and a first irradiation step of irradiating the object with the first ultraviolet light for 2.5 seconds or more; After the first irradiation step, a second irradiation step of irradiating the object with a second ultraviolet light having a peak wavelength of 260 nm or more and 290 nm or less, a radiant exposure of 10.5 mW / cm ２ or more, and an irradiation time of 2.5 seconds or more is included, A method of irradiating ultraviolet light for curing the object having a thickness of 10 μm or more.

2. The irradiance of the first ultraviolet light in the first irradiation step is 384 mW / cm ２ or more, The irradiance of the second ultraviolet light in the second irradiation step is 14.0 mW / cm ２ or more. The method for irradiating ultraviolet light according to claim 1.

3. After the first irradiation step and before the second irradiation step, a third ultraviolet light having a peak wavelength of 300 nm or more and 350 nm or less, a radiation irradiance of 6 mW / cm ２ or more, and an irradiation time of 2.5 seconds or more is further included to irradiate the object, and the ultraviolet light irradiation method according to claim 1.

4. The integrated light amount of the ultraviolet light irradiated on the object is 22.1 J / mm ２ or more. The method for irradiating ultraviolet light according to claim 1.

5. The method of irradiating ultraviolet light according to claim 1, wherein the object after performing the second irradiation step has good tackiness.

6. The method of irradiating ultraviolet light according to claim 1, wherein the ultraviolet light is light using a light-emitting diode as a light source.

7. An ultraviolet light irradiation device comprising an irradiation unit that executes the method of irradiating ultraviolet light according to any one of claims 1 to 6.

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