JP2017144641A - Inkjet device and ink application method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet device which prevents entry of reflection light of ultraviolet light into a surface of an application head when a UV curable ink is applied to a thick coated object having a curved surface form.SOLUTION: An inkjet device includes: an application head 52 having a nozzle for discharging a UV curable ink; a stage 51 which is disposed facing the application head, fixes a coated object 30, and moves relative to the application head; an ultraviolet lamp 53 which is disposed behind the application head in a relative movement direction; and a control part which changes an ultraviolet irradiation direction of the ultraviolet lamp in conjunction with relative movement.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ink jet apparatus and an ink application method. In particular, the present invention relates to an ink jet apparatus that performs application of ultraviolet curable ink droplets and an ink application method.

  2. Description of the Related Art Conventionally, an ink jet apparatus has been widely used in order to apply a recording image or various materials to an object to be coated such as a predetermined image or pattern at a low cost. By moving the coating head installed in the inkjet device and the stage on which the coating object is fixed relatively, and ejecting ink from the coating head onto the coating object, a predetermined image or pattern is formed on the coating object. Form.

  In recent years, ultraviolet curable ink (hereinafter referred to as ultraviolet curable ink) is often used as ink ejected from a coating head. The ultraviolet curable ink is superior in weather resistance and water resistance as compared with the water-soluble ink, and thus has an advantage of wide use.

  In addition, the ultraviolet curable ink does not contain a solvent component as compared with the oil-based ink, so it is easy for the working environment. The oil-based ink takes a long time to dry the ink that has landed on the coated object. Since the ink is cured instantaneously by irradiating light (UV), the workability and productivity are excellent.

  These objects to be applied using ultraviolet curable ink are generally applied to a planar shape such as paper, but in recent years, a thick curved surface as the shape of an object for forming an image or a pattern. There is a need for direct application to shapes and the like.

  In an inkjet apparatus in which a predetermined image or pattern is formed on an object to be coated by discharging ultraviolet curable ink from the coating head, an ultraviolet irradiation device is usually installed in the vicinity of the coating head. After the ultraviolet curable ink is landed on the object to be coated from the coating head, the ultraviolet curable ink on the object to be coated is cured by irradiating this region with ultraviolet light from the ultraviolet irradiation device.

  The ultraviolet irradiation device is installed in a direction perpendicular to the object to be coated. When the object is irradiated with ultraviolet rays, the ultraviolet rays are reflected on the surface of the object to be diffused. The ultraviolet diffused light may be incident on the surface of the coating head of the ink jet apparatus.

  When ultraviolet rays are incident on the surface of the coating head, the ink in the nozzle for discharging the ultraviolet curable ink from the coating head thickens, or the ink is cured in some cases. Due to the thickening and curing of the ink in the nozzle, the ejection of the ink ejected from the nozzle becomes unstable, or the nozzle is clogged and the ink is not ejected, resulting in poor coating.

  For this reason, maintenance of the coating head, replacement work of the coating head, and the like frequently occur, which is a factor that reduces productivity.

  Therefore, there is an ink jet apparatus described in Patent Document 1. The ink jet apparatus described in Patent Document 1 will be described with reference to FIGS. 3 (a) and 3 (b). As shown in FIG. 3A, the inkjet apparatus of Patent Document 1 includes an application head 10 that discharges ultraviolet curable ink, an ultraviolet ray source 11 that includes a shielding member 12 installed on the rear side in the relative movement direction, It is comprised from the stage 14 in which the coating material 13 was installed.

  FIG. 3B shows a state in which the object to be applied with the ink is a thick curved object 30 to be coated, and the coating head 10 and the ultraviolet ray source are separated from the stage 14. It is necessary to install in the state.

  As shown in FIG. 3A, when the object to be coated 13 has a planar shape, ultraviolet curable ink is applied from the coating head to the object to be coated 13 placed on the stage 14. Thereafter, when the ultraviolet curable ink is cured by irradiating the ultraviolet ray 20, the reflected light 21 of the ultraviolet ray 20 emitted from the ultraviolet ray source 11 is applied to the coating head 10 by the shielding member 12 provided in the ultraviolet ray source 11. Directly or indirectly. For this reason, it is possible to prevent the viscosity increase of the ink in the nozzle of the coating head 10 and the ink curing, and it is possible to reduce the maintenance load and perform stable coating over the long term.

  In addition, there is an ink jet apparatus described in Patent Document 2. The inkjet device described in Patent Document 2 will be described with reference to FIGS. 4 (a) and 4 (b). In the ink jet apparatus described in Patent Document 2, as shown in FIG. 4A, the application head 10 for discharging the ultraviolet curable ink is located away from the application head, and is inclined to the direction away from the application head. The ultraviolet irradiation device 32 and the stage 14 on which the workpiece 13 is installed.

  FIG. 4B shows a state where the object to be coated with ink is a thick curved object 30 to be coated, with the coating head 10 and the ultraviolet ray source separated from the stage 14. It is necessary to install.

  As shown in FIG. 4A, when the object to be coated 13 has a planar shape, ultraviolet curable ink is applied from the coating head 10 to the object to be coated 13 placed on the stage 14. Thereafter, when the ultraviolet ray 20 is irradiated to cure the ultraviolet curable ink, the ultraviolet ray irradiation device 32 is inclined in a direction away from the coating head 10. For this reason, since the scattering of the ultraviolet rays 20 does not diffuse in the direction of the coating head 10, the UV irradiation to the nozzles of the coating head 10 can be almost eliminated. For this reason, a maintenance load can be reduced and stable coating can be performed over a long period of time.

JP 2004-314304 A JP 2009-226692 A

  However, in the ink jet devices described in Patent Document 1 and Patent Document 2, as shown in FIGS. 3 (b) and 4 (b), when the coating object to be coated is a thick curved surface, the coating is performed. Since the thickness of the object is large, it is necessary to perform the discharge of the ultraviolet curable ink and the curing with the ultraviolet light by greatly separating the distance between the coating head and the stage on which the coating object is fixed.

  When a thick curved object 30 on the stage 14 is applied with the ink jet apparatus described in Patent Document 1, as shown in FIG. 3B, the ultraviolet rays from the ultraviolet ray source 11 depend on the position of the object 30. When 20 is reflected by the object 30 to be coated, there is a case where it is not shielded by the shielding member 12. As a result, the reflected ultraviolet light 21 is incident on the surface of the coating head, causing an increase in the viscosity of the ink in the nozzles of the coating head 10 and solidification of the ink, causing defective ejection from the coating head 10.

  When the thick curved object 30 on the stage 14 is applied by the ink jet apparatus described in Patent Document 2, as shown in FIG. 4B, the ultraviolet irradiation device 32 moves away from the application head 10. In the object 30 to be coated, a portion 31 of the surface opposite to the coating head 10 is shaded when irradiated with ultraviolet rays and is not irradiated with UV, and an image quality caused by uncured ultraviolet curable ink is generated in this portion. Incurs a decline.

  The present invention solves the above-mentioned conventional problems. When a thick curved object to be coated is applied with an ultraviolet curable ink, the reflected light of ultraviolet rays is prevented from entering the surface of the coating head. It is an object of the present invention to provide an ink jet apparatus and an ink application method for irradiating ultraviolet rays on the entire surface.

  In order to achieve the above object, a coating head having a nozzle for discharging ultraviolet curable ink and a coating head disposed to face the coating head, fix an object to be coated, and move relative to the coating head. An inkjet apparatus including a stage, an ultraviolet irradiation device disposed behind the relative movement direction of the coating head, and a control unit that changes the ultraviolet irradiation direction of the ultraviolet irradiation device in conjunction with the relative movement is used.

  In addition, a coating process in which an ultraviolet curable ink is discharged from a coating head in which a plurality of nozzles are arranged to an object to be coated, an irradiation process in which the ultraviolet curable ink is irradiated with ultraviolet rays from an ultraviolet irradiation device, and the ultraviolet curing. An ink application method including a changing step of changing an ultraviolet irradiation angle of the ultraviolet irradiation device so that the ultraviolet light reflected by the mold ink is not irradiated on the nozzle.

  As described above, according to the ink jet apparatus of the present invention, the direction of the ultraviolet ray irradiated from the ultraviolet ray irradiation device to the coated object can be arbitrarily changed when the ultraviolet ray is irradiated after the ultraviolet curable ink is discharged onto the coated object. Can do. At this time, the surface of the object to be coated is always irradiated with ultraviolet rays, and the inclination of the ultraviolet irradiation device can be controlled so that the ultraviolet rays do not hit the coating head surface. Thus, UV curable ink can be applied.

(A) The perspective view of the inkjet apparatus in embodiment, (b) Sectional drawing which showed the positional relationship of the coating head, ultraviolet irradiation device, and to-be-coated object of the inkjet apparatus in embodiment (A)-(c) is process drawing of apply | coating an ultraviolet curable ink to a to-be-coated article, and irradiating an ultraviolet-ray with the inkjet apparatus of embodiment. (A)-(b) Sectional drawing which shows the conventional inkjet apparatus described in patent document 1 (A)-(b) Sectional drawing which shows the conventional inkjet apparatus described in patent document 2

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment)
<Whole device>
FIG. 1A is a perspective view of an ink jet apparatus according to an embodiment of the present invention. The ink jet apparatus according to the embodiment includes a movable stage 51 installed on a gantry 50 and a support frame 54 for installing an application head 52 and an ultraviolet irradiation device 53 on the gantry 50.

  The base 50 uses a surface plate having a structure having high rigidity and high flatness (for example, a stone surface plate). On the gantry 50, a stage 51 that can move in the vertical direction and the horizontal direction with respect to the coating head 52 is installed. The stage 51 is connected to a ball screw 55 in each direction so that it can freely move in the vertical and horizontal directions with respect to the coating head 52. A motor 56 for rotating the ball screw 55 is connected to the ball screw 55, and the position of the stage 51 is freely moved by controlling the rotation of the motor 56. The motor 56 is connected to a control device for controlling the rotation of the motor 56, and can be moved to a predetermined position on the gantry 50 at an arbitrary speed by a command from the control device.

  Small small holes are formed on the surface of the stage 51, and these holes can be evacuated. An object to be coated on which ultraviolet curable ink is to be applied is placed on the stage 51, and the object to be coated can be fixed by vacuum suction of a small hole on the stage 51.

  A gate post type gantry 57 is installed on the frame so as to straddle the frame 50. The gantry 57 is configured by a support frame 54 having high rigidity like the gantry 50. A gantry 57 is provided with a support frame 54 on which a coating head 52 and an ultraviolet irradiation device 53 are installed. This support frame 54 uses a support frame 54 having a high rigidity so that there is almost no deformation even if the coating head 52 and the ultraviolet irradiation device 53 are attached.

  A bracket for attaching the coating head 52 is installed on the gantry 57 side of the support frame 54. This bracket has an adjustment mechanism that can adjust the parallelism between the surface of the coating head 52 and the surface of the stage 51 and the distance between the coating head 52 and the stage 51. With this adjustment mechanism, the coating head 52 is installed in a state where the parallelism between the coating head 52 and the stage 51 and the distance between the coating head 52 and the stage 51 are appropriately adjusted.

  In FIG. 1A, only one head is instructed for the coating head 52, but actually, a plurality of heads are installed side by side in the longitudinal direction of the stage to discharge a plurality of ultraviolet curable inks.

  In the coating head 52, a plurality of nozzles for discharging ultraviolet curable ink are arranged. In order to discharge the ultraviolet curable ink from each nozzle, an application head that discharges the ultraviolet curable ink by changing the internal pressure in each nozzle by a piezoelectric element was used. In order to control the discharge amount of the coating liquid discharged from each nozzle, it is necessary to control the voltage of the piezoelectric element installed in each nozzle. The coating head 52 is connected to a control device for controlling the piezoelectric elements installed in the nozzles. By controlling the piezoelectric elements of the nozzles of the coating head 52 from the control device, the requested coating pattern can be obtained. Ink for application can be discharged. An ink supply pipe (not shown) for supplying ultraviolet curable ink is connected to the coating head 52, and the ultraviolet curable ink is appropriately supplied to the coating head 52 to stably discharge the ultraviolet curable ink. ing.

  An ultraviolet irradiation device 53 is attached to the front end side of the support frame 54 on which the coating head 52 is installed via a shaft. The shaft is provided with a motor 58 for rotating the shaft. By rotating the shaft, the direction of the ultraviolet irradiation device 53 attached to the shaft can be freely changed. A control device for controlling rotation of the motor is connected, and the angle of the ultraviolet irradiation device 53 is controlled by performing necessary rotation at a necessary timing.

<Detailed layout>
FIG. 1B is a sectional view showing the arrangement of the coating head 52, the ultraviolet irradiation device 53, and the thick curved object 30 placed on the stage 51. The stage 51 is moved in the direction of the arrow. The coating head 52 installed on the support frame 54 is installed so that the surface of the coating head 52 and the top of the coating object 30 (the part farthest from the stage) have a gap of about 1 to 2 mm. In this example, the coating head 52 and the ultraviolet irradiation device 53 are fixed on the support frame 54. The ultraviolet irradiation device 53 can rotate at that position and can change the ultraviolet irradiation direction.

  Note that the stage 51 may be moved relative to the coating head 52 and the ultraviolet irradiation device 53. The coating head 52 is located behind the stage 51 in the direction of relative movement, and the ultraviolet irradiation device 53 is located ahead. The coating head 52 approaches the coating object 30 on the stage 51 first, and then the ultraviolet irradiation device 53 approaches the coating object 30.

  The ultraviolet irradiation device 53 installed on the support frame 54 is installed at a position where the tip (irradiation port) of the ultraviolet irradiation unit of the ultraviolet irradiation device 53 is about 10 mm higher than the surface of the coating head 52 (lower surface, nozzle surface). Tilt to. The angle at which the ultraviolet irradiation device 53 is inclined is set at an angle toward the center of the radius of curvature of the curved surface of the coating object 13 when the ultraviolet irradiation device is positioned at the end of the coating object.

  The ultraviolet irradiation device 53 and the coating head are set at a distance L that is longer than the position where the extended line of the tangent line 61 between the inclination angle 60 and the curved surface of the object to be coated and the edge of the coating head surface on the ultraviolet irradiation device side intersect. Installed at a position away from 52.

<Application operation>
Fig.2 (a)-FIG.2 (c) are the figures which showed application | coating operation | movement in time series. A thick curved object 30 placed on the stage 51 is moved in the direction of the arrow shown in the figure (from right to left) and applied to the object 30. The coating head 52 and the ultraviolet irradiation device 53 are fixed, and the application of the ultraviolet curable ink from the coating head 52 and the irradiation of the ultraviolet light 20 from the ultraviolet irradiation device 53 are continuously performed on the object 30 by moving the stage 51. By performing, a coating pattern can be formed on the surface of the article 13 to be coated.

<Initial>
FIG. 2A shows an initial state in which ultraviolet curable ink is ejected from the coating head 52 to the object to be coated 30, and the ultraviolet curable ink is coated on the surface of the object to be coated 30. At this time, the ultraviolet irradiation device 53 is inclined in the direction of the coating head 52 to irradiate the coating object 30 with the ultraviolet rays 20. This is because the intensity of the ultraviolet ray 20 emitted from the ultraviolet ray irradiation device 53 is not uniform, and if the ultraviolet ray 20 is irradiated in a vertical state, the ultraviolet curable ink is distributed in a cured state depending on the position of the coating object 30.

  As shown in FIG. 2 (a), the ultraviolet rays 20 are irradiated with the side surface of the object to be coated 30 on which the ultraviolet curable ink is applied and UV cured. At this time, the ultraviolet rays 20 irradiated from the ultraviolet irradiation device 53 are reflected and diffused on the surface of the coating object 30. However, even if these reflected ultraviolet rays 20 and diffused ultraviolet rays 20 are diffused at maximum with respect to the direction of the coating head 52, the direction of the tangent 61 with the object to be coated 30 at the inclination angle 60 of the ultraviolet irradiation device 53. Therefore, it hits the side surface of the coating head 52 but does not reach the surface of the coating head 52.

<Medium term> (Point to rotate)
From FIG. 2A, the stage 51 moves to become FIG. 2B. FIG. 2B shows a limit region where the ultraviolet ray 20 irradiated from the ultraviolet ray irradiation device 53 hits the coating head 52 when reflected and diffused on the surface of the object to be coated 30.

  When the coating object 30 moves to this position, the direction of the ultraviolet irradiation device 53 is turned to an angle opposite to the coating head 52. The position of the limit region is a position where a tangent line 61 with the workpiece 13 at an inclination angle 60 of the ultraviolet irradiation device 53 and a perpendicular line 62 on the coating head side end surface of the UV irradiation opening of the ultraviolet irradiation device 53 intersect. . If the coating object 30 moves beyond this position and the ultraviolet irradiation device 53 is tilted toward the coating head 52, the ultraviolet light reflected and diffused by the coating object 30 hits the surface of the coating head 52 and strikes the coating head 52. The ultraviolet curable ink in the arranged nozzles or the ultraviolet curable ink scattered on the surface of the coating head 52 is cured, which causes non-ejection of the ultraviolet curable ink.

  At this time, the diffusion range of the ultraviolet rays 20 irradiated from the ultraviolet irradiation device 53 includes a tangent line 61 with the coating object 13 at an inclination angle 60 of the ultraviolet irradiation device 53 and an end face on the coating head side of the UV irradiation opening of the ultraviolet irradiation device 53. The irradiation range of the ultraviolet rays 20 is adjusted so as not to extend beyond the position where the perpendicular line 62 intersects. Alternatively, a lens for converging the ultraviolet rays 20 is installed at the UV emission port of the ultraviolet irradiation device 53, and the diffusion of the ultraviolet rays 20 is limited by making the ultraviolet rays into a line shape.

<Final stage>
The stage 51 further moves from FIG. 2 (b), resulting in FIG. 2 (c).

  FIG. 2C shows a state in which ultraviolet curable ink is ejected from the coating head 52 to the object to be coated 13 and the direction of the ultraviolet irradiation device 53 is changed when the ultraviolet curable ink is applied to the surface of the object to be coated 30. Shows the state. After the direction of the ultraviolet irradiation device 53 is changed, the irradiation of the ultraviolet ray 20 is continued until the ultraviolet ray 20 is irradiated on the entire surface of the coating object 30 coated with the ultraviolet curable ink from the coating head 52.

<Summary>
As described above, after the ultraviolet curable ink is ejected onto the thick curved object 13 and then irradiated with the ultraviolet rays 20, the direction of the ultraviolet rays irradiated from the ultraviolet irradiation device 53 to the object 13 is determined. Adjust according to the position. Thus, the ultraviolet curable ink can be applied to the entire surface of the object to be coated 30. At this time, since the ultraviolet rays 20 are adjusted so as not to hit the surface of the coating head 52, stable coating can be performed without non-ejection due to UV curing.

  In addition, when the ultraviolet light 20 is irradiated to the thick article 13 in advance, an ultraviolet intensity meter is installed in the coating head 10 so that the ultraviolet irradiation device tilts 60 so that the ultraviolet light 20 is not diffused into the coating head 10. You may plan optimization.

  Based on this proper value, after the ultraviolet curable ink is discharged from the coating head 10 to the object 13 to be coated, the ultraviolet curable ink is cured while the ultraviolet irradiating device 53 is appropriately tilted, thereby causing the non-ejection of the coating head. Stable coating is possible.

  Moreover, as shown in FIG. 2A to FIG. 2C, the cylindrical object is described as an example of the object to be coated 30, but it has a curved surface shape in multiple directions like a hemispherical shape. The same applies to the coating object 30 that is present.

  Furthermore, it is preferable that the application surface (the lower surface, the surface with the nozzle) of the application head 52 is installed at a position lower than the ultraviolet irradiation port of the ultraviolet irradiation device 53. This is because, as can be seen from FIG. 2A to FIG. 2C, the ultraviolet light reflected by the object to be coated 30 is not irradiated onto the coated surface more.

  However, in this case, it is necessary to narrow the ink application width and apply the ink to the object to be coated 30 and irradiate with ultraviolet rays. The application width is set to such a width that the distribution of the intensity of the ultraviolet rays 20 that can cure the ultraviolet curable ink to the same quality in the width direction of the article to be coated 30 when the object to be coated 30 is irradiated with the ultraviolet rays 20. With respect to the center of the coating width, the ultraviolet irradiation device 53 is tilted and irradiated repeatedly as shown in FIGS. Stable application is possible without causing ejection failure of the head.

  In the above example, the coating head 52 and the ultraviolet irradiation device 53 are fixed on the support frame 54. However, the distance between the coating head 52 and the ultraviolet irradiation device 53 may be changed relatively. That is, the angle of the ultraviolet irradiation device 53 is made constant, and the distance between the coating head 52 and the ultraviolet irradiation device 53 is changed before the ultraviolet light reflected by the coating object 30 is irradiated to the nozzle. As a result, it is possible to prevent the nozzles from being irradiated with ultraviolet rays reflected by the object to be coated 30.

  In the same manner as described above, it is preferable to obtain an operation in which the distance between the coating head 52 and the ultraviolet irradiation device 53 is relatively changed so as not to irradiate the nozzle with ultraviolet rays, and use the data.

  The ink jet apparatus according to the embodiment can be used not only for industrial use but also for consumer use. For industrial use, it is possible to apply UV-curing ink and cure the ink on a coated object having a thick convex shape and a curved end portion. It can be used for decorating designs and applying functional films to devices with a three-dimensional structure. In addition, it is widely used as an inkjet coating method.

DESCRIPTION OF SYMBOLS 10 Application | coating head 11 Ultraviolet ray source 12 Shielding member 13 To-be-coated object 14 Stage 20 Ultraviolet 21 Reflected light 30 To-be-coated object 31 Area 32 Ultraviolet irradiation apparatus 50 Mount 51 Stage 52 Application head 53 Ultraviolet irradiation apparatus 54 Support frame 55 Ball screw 56 Motor 57 Gantry 58 Motor 60 Angle 61 Tangent 62 Perpendicular

Claims (6)

An application head having a nozzle;
A stage that is disposed to face the coating head, fixes an object to be coated, and moves relative to the coating head;
An ultraviolet irradiation device disposed in front of the coating head with respect to the direction of relative movement of the stage;
An inkjet apparatus comprising: a control unit that changes an ultraviolet irradiation direction of the ultraviolet irradiation apparatus in conjunction with the relative movement. The controller is
When starting to irradiate the UV to the coated object,
The ultraviolet irradiation direction of the ultraviolet irradiation device is irradiated with being inclined in the direction in which the coating head is installed,
When the nozzle is irradiated with the ultraviolet light reflected by the coated object,
The inkjet apparatus according to claim 1, wherein the ultraviolet irradiation direction of the ultraviolet irradiation device is inclined to the opposite side of the coating head to irradiate the ultraviolet light. When the control unit previously irradiates the application object with the ultraviolet light at each position of the application object, the ultraviolet light reflected by the application object is not applied to the nozzle of the application head. The inkjet apparatus according to claim 1 or 2, wherein an ultraviolet irradiation direction of the ultraviolet irradiation apparatus is obtained and the ultraviolet irradiation direction is changed. An application head having a nozzle;
A stage that is disposed to face the coating head, fixes an object to be coated, and moves relative to the coating head;
An ultraviolet irradiation device disposed in front of the coating head with respect to the direction of relative movement of the stage;
An inkjet apparatus comprising: a control unit that changes a distance between the ultraviolet irradiation device and the coating head in conjunction with the relative movement. 5. The inkjet apparatus according to claim 1, wherein a coating surface of the coating head is installed at a position lower than an ultraviolet irradiation port of the ultraviolet irradiation apparatus. A coating step of discharging ultraviolet curable ink to a coating object from a coating head in which a plurality of nozzles are arranged;
An irradiation step of irradiating the ultraviolet curable ink with ultraviolet rays from an ultraviolet irradiation device;
A changing step of changing an ultraviolet irradiation angle of the ultraviolet irradiation device so that the ultraviolet light reflected by the ultraviolet curable ink is not irradiated on the nozzle.

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