Coating device and coating system

Abstract

Provided is a coating device 1 which comprises: a coating processing unit 30 for performing predetermined coating processing with respect to a printed surface of a workpiece 2, which is a sheet-like object or a plate-like object having a surface that has been subjected to electronic print processing; a pair of pressure rollers 21, 22 which are arranged upstream or downstream of the coating processing unit 30 and which deliver the workpiece 2 while sandwiching and applying pressure to the workpiece 2; and a heating unit 23, 57 which is arranged in the same position as the pair of pressure rollers 21, 22 or upstream thereof, with respect to a conveying direction of the workpiece 2, and which heats the printed surface of the workpiece 2.

Description

Coating equipment and coating system

[0001] The present invention relates to a coating device and a coating system for coating a workpiece, such as a sheet or plate, whose surface has been subjected to a printing process.

[0002] Electronic printing printers (laser printers, LED printers, etc.) and inkjet printers are widely used as devices for printing on sheet-like or plate-like workpieces. Electronic printing printers use a laser or LED light source to attach toner to an inverse image formed on the surface of a drum, which is then transferred to the surface of the workpiece. Heat and pressure are then applied to fix the toner to the surface, forming a printing layer on the surface. Inkjet printers form a printing layer on the surface of the workpiece by spraying fine particles of liquid ink onto the surface.

[0003] In order to protect the printed layer formed on the surface of the workpiece in this way and to make the printed layer glossy, a process is carried out in which the surface of the workpiece (printed surface) after the printed layer has been formed is covered with a coating agent (for example, Patent Document 1).

[0004] JP 63-278847 A JP 2000-143030 A

[0005] When the same coating process was applied to workpieces on which printing layers had been formed using various electronic printing printers and inkjet printers sold by various manufacturers, it was found that the coating layer was prone to peeling off on workpieces on which printing layers had been formed using some electronic printing printers.

[0006] The problem that the present invention aims to solve is to provide a technology that prevents the coating layer from peeling off after a coating process is applied to a workpiece that is a sheet or plate-like object that has been subjected to electronic printing.

[0007] The coating device of the present invention, which has been made to solve the above problems, comprises a coating processing section that performs a predetermined coating process on the printed surface of a workpiece, which is a sheet-like or plate-like object whose surface has been subjected to an electronic printing process; a pair of pressure rollers that are arranged upstream or downstream of the coating processing section and that sandwich and pressurize the workpiece while sending it out; and a heating section that is arranged at the same position as the pair of pressure rollers or further upstream in the conveying direction of the workpiece and that heats the printed surface of the workpiece.

[0008] The predetermined coating treatment can be any of various conventionally known treatments, including, for example, a coating treatment using UV varnish or a coating treatment using water-based varnish.

[0009] The inventors conducted a peeling test in which adhesive tape was applied to and peeled off a workpiece coated using a conventional coating device. The results showed that, for workpieces printed using some electronic printing printers, the coating peeled off along with a portion of the printed layer. The printed layer of a printed item produced using an electronic printing printer is composed of toner. The peeling of the coating layer along with a portion of the printed layer is believed to be due to the toner not sufficiently coagulating and adhering to the printed surface when the printed item is produced using the electronic printing printer. In addition to a coating treatment unit that applies a coating to the printed surface, the present invention also includes a pair of pressure rollers located upstream or downstream of the coating treatment unit and applying pressure to the workpiece by sandwiching it between them, and a heating unit located at the same position as or upstream of the pair of pressure rollers in the workpiece transport direction and heating the printed surface of the workpiece. The heating unit heats the printed surface, and the pair of pressure rollers either directly pressurize the printed surface (if the pair of pressure rollers is located upstream of the coating treatment unit) or indirectly pressurize the printed surface via the coating formed by the coating treatment (if the pair of pressure rollers is located downstream of the coating treatment unit). Therefore, the toner aggregates and is more reliably fixed to the printing surface, and peeling of the coating layer after coating treatment can be suppressed.

[0010] In the coating device according to the present invention, it is preferable that the heating section heats the printing surface of the workpiece simultaneously with the application of pressure by the pair of pressure rollers.

[0011] In the coating device of the above embodiment, the toner can be more efficiently aggregated and fixed to the printing surface.

[0012] In the coating device according to the present invention, it is preferable that the pressure roller pair is arranged upstream of the coating processing section, and that the surface of the roller of the pressure roller pair that is positioned on the side that comes into contact with the printing surface is made of a material with a friction coefficient of 0.1 or less.

[0013] In the coating device of the above embodiment, the printing surface is heated and pressurized directly without passing through the coating surface, allowing the toner to aggregate and be more reliably fixed to the printing surface. In the coating device of the above embodiment, the surface of the roller that contacts the printing surface is made of a material with a low friction coefficient of 0.1 or less, which reduces the adhesion and wettability of the roller surface and prevents toner from adhering. Fluorine resin, for example, can be used as a material with a friction coefficient of 0.1 or less.

[0014] The coating device of the present invention aggregates the toner and fixes it to the printing surface, so that after a coating process is applied to a workpiece that has undergone electronic printing processing, the toner layer can be prevented from separating and peeling off along with the coating layer.

[0015] FIG. 1 is an overall configuration diagram of a first embodiment of a coating apparatus according to the present invention. FIG. 2 is a schematic diagram illustrating the configuration of a toner aggregation section of the coating apparatus of the first embodiment. FIG. 3 is a schematic diagram illustrating the configuration of a coat section of the coating apparatus of the first embodiment. FIG. 4 is a schematic diagram illustrating the configuration of a varnish curing section of the coating apparatus of the first embodiment. FIG. 5 is an overall configuration diagram of a second embodiment of a coating apparatus according to the present invention. FIG. 6 is a diagram illustrating the configuration of a workpiece cooling section of the coating apparatus of the second embodiment. FIG. 7 is a schematic diagram illustrating the configuration near the sheet transport section in the workpiece cooling section of the coating apparatus of the second embodiment.

[0016] Two embodiments of the coating apparatus according to the present invention will be described below with reference to the drawings. Both the coating apparatus 1 of the first embodiment and the coating apparatus 100 of the second embodiment are apparatuses that coat the surface of a paper sheet that has been subjected to a printing (electronic printing) process using an electronic printing printer (laser printer, LED printer, etc.) with UV varnish. Note that in the drawings used in the following description, each part is shown at a scale different from the actual size, as appropriate, to clearly show the configuration of each part.

[0017] FIG. 1 is an overall perspective view of a coating apparatus 1 according to a first embodiment. However, in FIG. 1, the top and front side of the external housing, as well as some of the internal components, are not shown in order to illustrate the internal structure. The coating apparatus 1 includes, in order from the upstream side of the transport of the paper sheets, the object to be processed, a paper feed unit 10, a toner agglomeration unit 20, a coating unit 30, a transport unit 40, a varnish curing unit 50, and a stacking unit 60. The paper feed unit 10 to the coating unit 30, the transport unit 40, the varnish curing unit 50, and the stacking unit 60 are each integrated into a unit, and the coating apparatus 1 is configured by connecting each unit in sequence. The coating apparatus 1 also includes a control unit 80 that controls the operation of each of these units. For convenience, the direction in which the paper sheets are transported will be referred to as "forward" in the following description.

[0018] The paper feed unit 10 is a device that supplies paper sheets to the toner aggregation unit 20 located downstream, and includes a stacking unit 11 and a transport mechanism 12. In the stacking unit 11, uncoated paper sheets are stacked so that the processed surface (coated surface) that has been previously subjected to printing faces up. The transport mechanism 12 takes in the paper sheets stacked in the stacking unit 11 one by one and supplies them to the toner aggregation unit 20.

[0019] The toner agglomeration unit 20 is a device that aggregates the toner in the printing layer of the paper sheet 2 supplied from the paper supply unit 10 and fixes it to the printing surface. FIG. 2 shows a schematic diagram of the toner agglomeration unit 20. The toner agglomeration unit 20 has a pair of rollers (upper roller 21 and lower roller 22) arranged one above the other. The upper roller 21 has a built-in halogen lamp 23. The lower roller 22 is positioned so as to press the paper sheet 2 supplied from the paper supply unit 10 toward the upper roller 21, and the distance between the upper roller 21 and the lower roller 22 is shorter than the thickness of the paper sheet 2. Therefore, the paper sheet 2 drawn between the upper roller 21 and the lower roller 22 is pressed by being sandwiched between the upper roller 21 and the lower roller 22 and is then heated by the halogen lamp 23 before being sent out.

[0020] The surface of the upper roller 21 is made of a material with a low coefficient of friction. The upper roller 21 in the first embodiment is a rubber roller 211 with a built-in halogen lamp 23 and a fluororesin tube 212 with a friction coefficient of 0.1 wound around its surface, and the lower roller 22 is a rubber roller (rubber roller). In the first embodiment, the halogen lamp 23, which corresponds to the heating section in the present invention, is provided at the same position as the pair of pressure rollers consisting of the upper roller 21 and lower roller 22 in terms of the conveying direction of the workpiece sheet 2.

[0021] The coating unit 30 is a device that applies UV varnish to the upper surface (the surface to be treated) of the paper sheet 2 supplied from the toner aggregation unit 20. The coating unit 30 in the first embodiment has the same configuration as the coating unit in the embodiment described in the previous application by the present applicant (Patent Application No. 2022-172954). Only the essential parts will be described here.

[0022] The coating unit 30 includes an upper roller 31 and a lower roller 32, positioned above and below the path of the sheet 2 conveyed from the paper feed unit 10. Figure 3 shows a schematic diagram of the coating unit 30, including the upper roller 31 and the lower roller 32. The upper roller 31 has a groove formed in the width direction of its circumferential surface, corresponding to the width where the UV varnish is applied to the sheet 2. The upper roller 31 is preferably made of a rigid material, such as a gravure rod. The lower roller 22 has a width corresponding to the width where the UV varnish is applied to the sheet 2. The elastic roller portion has at least its circumferential surface made of a resilient material (e.g., rubber), and rigid roller portions (metal collars) at both ends of the elastic roller portion made of a rigid material (e.g., stainless steel). The diameter of the rigid roller portion (metal collar) is slightly larger (e.g., 0.2 mm) than the diameter of the elastic roller portion (rubber roller), with this difference being smaller than the thickness of the sheet 2. In this way, by making the height difference between the surface of the elastic roller portion and the surface of the rigid roller portion (metal collar) smaller than the thickness of the paper sheet 2, when the paper sheet 2 is not sandwiched, the circumferential surface of the grooved roller portion and the circumferential surface of the elastic roller portion are separated, preventing UV varnish from adhering to the circumferential surface of the elastic roller portion, and when the paper sheet 2 is sandwiched, the paper sheet 2 can be abutted against the circumferential surface of the grooved roller portion to apply UV varnish to the surface of the paper sheet 2.

[0023] A doctor blade 33, which is a plate-shaped member that makes linear contact with the circumferential surface of the upper roller 31, is located on the circumferential surface of the upper roller 31, at a position before the contact point with the lower roller 32 in the rotational direction of the upper roller 31 (upstream in the conveying direction of the paper sheets 2). Plate-shaped sidewall members are provided on both ends of the linear contact point between the upper roller 31 and the doctor blade 33, closing the sides of the space between the circumferential surface of the upper roller 31 and the surface of the doctor blade 33. The space surrounded by the upper roller 31, doctor blade 33, and sidewall members is used as a varnish reservoir 34. Liquid varnish is supplied to the varnish reservoir 34 from a varnish supply unit 35 provided above it.

[0024] The conveying unit 40 is a device that conveys the paper sheets 2 that have been coated with UV varnish in the coating unit 30 to the varnish curing unit 50 located downstream. The conveying unit 40 includes a conveying table 41, two belts 42 wound around the conveying table 41, and a drive unit (not shown) that rotates the two belts 42.

[0025] The varnish curing unit 50 is a device that cures the UV varnish applied to the paper sheets 2 transported from the transport unit 40. Figure 4 shows a schematic configuration of the varnish curing unit 50. As shown in Figure 4, the varnish curing unit 50 includes a resin film supply roller 51, a first upper resin film pressing roller 52, a first lower resin film pressing roller 53, a second resin film pressing roller 54, a resin film recovery roller 55, and a UV light source 56.

[0026] The resin film pressing first upper roller 52 and the resin film pressing first lower roller 53 have the same configuration as the upper roller 21 and the lower roller 22 in the toner agglomeration section 20. That is, a halogen lamp 57 is built into the resin film pressing first upper roller 52. The resin film pressing first lower roller 53 is arranged so as to press the sheet 2 from below toward the resin film pressing first upper roller 52, and the distance between the resin film pressing first upper roller 52 and the resin film pressing first lower roller 53 is shorter than the thickness of the sheet 2. Therefore, the sheet 2 drawn between the resin film pressing first upper roller 52 and the resin film pressing first lower roller 53 is pressed by being sandwiched between the resin film pressing first upper roller 52 and the resin film pressing first lower roller 53, and is then heated by the halogen lamp 57 while being sent out.

[0027] The surface of the resin film pressing first upper roller 52 is made of a material with a low coefficient of friction. The resin film pressing first upper roller 52 in the first embodiment is formed by wrapping a fluororesin tube 522 around the surface of a rubber roller 521 incorporating a halogen lamp 57, and the resin film pressing first lower roller 53 is also a rubber roller. In the first embodiment, the halogen lamp 57, which corresponds to the heating section in the present invention, is also provided at the same position as the pair of pressure rollers consisting of the resin film pressing first upper roller 52 and the resin film pressing first lower roller 53, with respect to the conveying direction of the workpiece sheet 2.

[0028] The resin film supply roller 51 is formed by winding a long resin film 58. The resin film pressing first upper roller 52 and the resin film pressing first lower roller 53 sandwich and transport the paper sheet 2 along the transport path (the path indicated by the dashed line in FIG. 4 ). When the paper sheet 2 is sandwiched between the resin film pressing first upper roller 52 and the resin film pressing first lower roller 53, the resin film 58 supplied from the resin film supply roller 51 is pressed against the upper surface of the paper sheet 2. The resin film supply roller 51 rotates in response to this rotation. This causes the resin film 58 to be airtightly attached to the upper surface of the paper sheet 2, and air (especially oxygen gas that inhibits the curing of the coating agent) present between the resin film 58 and the paper sheet 2 is expelled. The resin film recovery roller 55 recovers the resin film 58 by winding it from the paper sheet 2 after the UV varnish has cured.

[0029] The UV light source 56 is located between the pressure roller pair consisting of the resin film pressing first upper roller 52 and the resin film pressing first lower roller 53 and the resin film pressing second roller 54, and irradiates the UV varnish-coated surface of the paper sheet 2, to which the resin film 58 is airtightly attached, with ultraviolet light. The resin film 58 is made of a material that transmits ultraviolet light, and the UV varnish applied to the surface of the paper sheet 2 is cured by the ultraviolet light passing through the resin film 58 and irradiating it. After the resin film 58 is peeled off, the paper sheet 2 is sent to the stacking section 60 and stacked. While the resin film 58 is used here, other materials may be used as long as they transmit the light emitted from the light source 56 and can be airtightly attached to the top surface of the paper sheet 2. Furthermore, because the resin film 58 directly contacts the printing surface, it is preferable that at least the surface that contacts the printing surface be made of a material with a low coefficient of friction, similar to the surface of the upper roller 21. Specifically, it is preferable that the material has a friction coefficient equal to or less than 0.1, which is the friction coefficient of fluororesin.

[0030] The control unit 80 controls the operation of each of the above-mentioned units. The control unit 80 is actually a personal computer, and the required functions are realized by executing a dedicated program pre-installed on the processor. The control unit 80 is equipped with a memory unit 81 in which various information related to the coating process is stored. The control unit 80 is also connected to an input unit 82 consisting of a keyboard, mouse, etc., which allows the user to perform appropriate input operations, and a display unit 83 consisting of a liquid crystal display, etc., which displays appropriate information such as a setting screen for coating process conditions and the status of the device.

[0031] Next, a process flow for coating the entire surface of a paper sheet 2, the surface of which has been subjected to a printing process by an electronic printing printer, with UV varnish using the coating device 1 of the first embodiment will be described.

[0032] The sheets 2, the surfaces of which have been subjected to printing processing by the electronic printing printer, are stacked in advance in the stacking section 11 of the paper feed section 10 with the printed surface (the surface to be processed) facing up.

[0033] When the user instructs coating processing of the printing sheet 2 by performing a predetermined input operation via the input unit 82, the control unit 80 executes coating processing of the printing sheet 2 as follows.

[0034] In the paper feed unit 10, the paper sheets 2 stacked in the stacking unit 11 are sent one by one from the top to the toner condensing unit 20. In the toner condensing unit 20, the printed layer of the paper sheet 2 is pressed by being sandwiched between an upper roller 21 and a lower roller 22, and at the same time, the printed layer is heated by a halogen lamp 23 built into the upper roller 21. In the toner condensing unit 20, the paper sheet 2 that has been printed by the electronic printing printer is further heated and pressurized, thereby condensing the toner and more reliably fixing it to the printed surface.

[0035] In the coating section 30, UV varnish stored in a varnish reservoir 34 is applied to the entire circumferential surface of the upper roller 31. Next, a doctor blade 33 removes the UV varnish from the circumferential surface of the upper roller 31, leaving only the UV varnish that has penetrated into the grooves formed in the circumferential surface of the upper roller 31. The upper roller 31 and lower roller 32 sandwich the paper sheet 2 delivered from the paper feed section 10 and deliver it forward. At this time, the rigid roller portions located at both ends of the upper roller 21 and lower roller 22, which are made of a rigid material, abut against each other without deforming. Meanwhile, the elastic roller portions are compressed and elastically deformed when abutting against the upper roller 31. This presses the paper sheet 2 against the upper roller 31, causing the UV varnish to flow out of the grooves in the circumferential surface of the upper roller 31 and adhere to the top surface of the paper sheet 2.

[0036] The paper sheet 2 sent out from the coating section 30 is then transported by the transport section 40 and enters the varnish curing section 50. In the varnish curing section 50, as described above, the paper sheet 2 is sandwiched and pressurized between the resin film pressing first upper roller 52 and the resin film pressing first lower roller 53, and is simultaneously heated by the halogen lamp 57 while being transported. As a result, the toner layer is coagulated, similar to the toner coagulation section 20, and is more reliably fixed to the printing surface.

[0037] The first upper resin film pressing roller 52 and the first lower resin film pressing roller 53 press the resin film 58 supplied from the resin film supply roller 51 against the upper surface of the paper sheet 2, airtightly adhering the resin film 58 to the UV varnish-coated surface of the paper sheet 2. This removes air (especially oxygen) from the UV varnish-coated surface and spreads the UV varnish evenly across the entire surface. The UV varnish is then cured by irradiation with ultraviolet light from the UV light source 56. The resin film 58 adhered to the UV varnish-coated surface is then collected by the resin film collection roller 55, and the UV-varnished paper sheet 2 is sent to the stacking section 60.

[0038] In an electronic printer, a reverse image formed with toner on the surface of a drum is transferred to the surface of a workpiece, and heat and pressure are applied to condense the toner and fix it to the printing surface, forming a printing layer on the surface.Thus, electronic printers also include a mechanism for fixing the toner by applying heat and pressure, but in some models, the degree of heat and pressure may not be sufficient.

[0039] The inventors prepared test papers by applying a UV varnish coating to sheets of paper that had been printed using various models of electronic printing printers sold by various companies, and then attached adhesive tape to the surface of these test papers and peeled it off.It was found that with some models of electronic printing printers, the coating layer peeled off along with the printing layer (toner layer).

[0040] In the coating device 1 of the first embodiment, the printing layer of the paper sheet 2 is simultaneously heated and pressurized by the pressure roller pair consisting of the upper roller 21 and lower roller 22 of the toner agglomeration unit 20, which agglomerates the toner and more reliably fixes it to the printing surface. Also, the pressure roller pair consisting of the first upper resin film pressing roller 52 and the first lower resin film pressing roller 53 of the varnish curing unit 50 simultaneously heats and pressurizes the printing layer of the paper sheet 2 via the resin film 58, which agglomerates the toner and more reliably fixes it to the printing surface. By heating and pressurizing the printing layer of the paper sheet 2 in this way, it is possible to prevent the coating layer from peeling off after coating the paper sheet 2 whose surface has been printed by an electronic printer.

[0041] In electronic printers, polyester particles are often used as toner. Therefore, it is considered effective to heat and pressurize the printed layer of the paper sheet 2 under conditions that partially melt the polyester particles. Specifically, for example, it is recommended to pressurize the printed surface of the paper sheet 2 at a temperature between 80°C and 150°C. The inventors used the same printed material in which the coating layer and toner layer peeled off in the peel test described above and subjected it to heating and pressurization treatment within the above temperature range using the coating device 1 of the first embodiment. The inventors were able to peel off the adhesive tape without peeling off the coating layer or toner layer. This confirmed that the toner layer was sufficiently cohesive and fixed to the printed surface with sufficient strength. On the other hand, when the heating temperature was lowered to 60°C, the toner layer was not fixed with sufficient strength and peeled off along with the coating layer. Furthermore, when the heating temperature exceeded 150°C, the toner melted and became liquid, potentially causing it to separate from the workpiece. Of course, these heating and pressurizing conditions are merely an example, and the heating and pressurizing conditions (temperature and pressure) can be appropriately determined taking into consideration the state of the printing layer (toner fixation state) and the like, based on the results of a peel test conducted on the paper sheet 2 to be coated or on a test paper created using the same model of electronic printing printer as the paper sheet to be coated. It goes without saying that the upper roller 21 and the first upper resin film pressing roller 52 should be made of a material that has sufficient heat resistance to the temperatures to which they are heated by the heat sources of the halogen lamps 23, 57 built into them.

[0042] The upper roller 21 of the toner agglomeration unit 20 directly contacts the printing surface of the paper sheet 2 and presses the printing layer against it. Using a rubber roller with a high coefficient of friction (e.g., a coefficient of friction of 2.3 or higher, as in Patent Document 2), as is commonly used in paper transport mechanisms, can result in toner adhesion to the roller surface. Therefore, the surface of the upper roller 21, which contacts the printing surface, is preferably made of a material with a low coefficient of friction. In the first embodiment, the upper roller 21 of the toner agglomeration unit 20 is made of a rubber roller 211 wrapped around its surface with a fluororesin tube 212, which has a low coefficient of friction of 0.1. This reduces the adhesion and wettability of the surface, thereby preventing toner transfer from the printing layer. In the first embodiment, the coefficient of friction is used as an index for reducing the adhesion and wettability of the surface of the upper roller 21. However, the surface of the upper roller 21 may be made of a material selected based on an index other than the coefficient of friction, as long as it is a physical quantity that reflects the characteristics of low adhesion and wettability. In addition, since the surface of the other roller (lower roller 22) that makes up the pressure roller pair is made of rubber with sufficient elasticity, the entire surface of the sheet 2 can be evenly pressurized when the sheet 2 is clamped.

[0043] Next, a coating apparatus 100 according to a second embodiment will be described. In the following description, components common to those of the coating apparatus 1 according to the first embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0044] 5 is a perspective view of the entire coating apparatus 100 of the second embodiment. As with FIG. 1, the top and front side of the external housing and some of the internal components of the apparatus are not shown in order to show the internal structure. The coating apparatus 100 includes the same components as those of the first embodiment, namely, the paper feed unit 10, the toner aggregating unit 20, the coating unit 30, the conveying unit 40, the varnish curing unit 50, and the collecting unit 60, as well as a workpiece cooling unit 70. The workpiece cooling unit 70 is disposed between the toner aggregating unit 20 and the coating unit 30.

[0045] The workpiece cooling section 70 is a device that cools the printing surface that has been heated in the toner agglomeration section 20. Fig. 6 is an enlarged view of the characteristic components of the workpiece cooling section 70, and Fig. 7 shows a cross section near the conveyance path of the paper sheet 2.

[0046] The workpiece cooling section 70 includes three upper rollers 71 located above the conveyance path for the paper sheet 2 and three lower rollers 72 located below the conveyance path, facing the upper rollers 71. The pair of rollers consisting of the upper rollers 71 and the lower rollers 72 corresponds to the cooling roller pair in this invention. It is preferable to use an upper roller 71 with at least the surface that contacts the printed surface made of a material with high thermal conductivity. Because metals generally have high thermal conductivity, the upper roller 71 is preferably a roller with at least its surface made of metal. In the second embodiment, the upper roller 71 is an aluminum pipe roller. Aluminum is particularly suitable for the upper roller 71 because it has high thermal conductivity and is relatively inexpensive. Because paper sheets 2 generally have thermal insulation properties, even if the surface of the lower roller 72 is made of a material with high thermal conductivity, the cooling effect on the printed surface is limited. Therefore, in this embodiment, a rubber roller is used as the lower roller 72. Of course, the lower roller 72 may also be made of a material with high heat dissipation efficiency, similar to the upper roller 71.

[0047] A gear is formed on one end of each of the three lower rollers 72 (the front side of the paper in FIG. 6 ), and a flat first gear 73 is arranged so as to mesh with the gears of the two adjacent lower rollers 72. A second gear 74 is arranged so as to mesh with this first gear 73 and a gear 751 of the motor 75. Therefore, when the motor 75 is operated, the lower roller 72 is rotated via the second gear 74 and the first gear 73, and when a sheet is sandwiched between them, the upper roller 71 rotates in response to the rotation of the lower roller 72.

[0048] Blower fans 76 that blow air downward are disposed at positions (two locations) above the upper rollers 71 and between two adjacent upper rollers. Although not shown in Fig. 6, a ventilation guide 77 that is open on both sides in the horizontal direction perpendicular to the sheet conveyance direction is disposed in the workpiece cooling section 70 so as to cover the above-mentioned components. Here, the blower fans 76 blow air, but they may also blow gases other than air.

[0049] In the coating apparatus 100 of the second embodiment, as in the coating apparatus 1 of the first embodiment, in the toner agglomeration section 20, the paper sheet 2 is sandwiched between an upper roller 21 and a lower roller 22 to apply pressure to the printed surface, and at the same time, the printed layer is pressed by a halogen lamp 23 built into the upper roller 21. In the toner agglomeration section 20, the paper sheet 2 that has been printed by the electronic printing printer is heated and pressurized, thereby agglomerating the toner and more reliably fixing it to the printed surface.

[0050] In the coating device 100 of the second embodiment, the sheet 2 heated in the toner agglomeration section 20 is transported by three pairs of upper rollers 71 and lower rollers 72. At this time, at least the surface of the upper roller 71 is made of a material with high thermal conductivity (aluminum, etc.), so when the printed surface of the sheet 2 comes into contact with the upper roller 71, heat is transferred from the sheet 2 to the upper roller 71, cooling the printed surface. The printed surface is also cooled by air blown onto the sheet 2 from the blower fan 76. Furthermore, air is blown from the blower fan 76 onto the upper roller 71, cooling the upper roller 71 which has absorbed heat from the sheet 2. In addition, a ventilation guide 77 with openings on both sides in the horizontal direction perpendicular to the sheet transport direction is provided, regulating the flow of air blown from the blower fan 76.

[0051] As described above, in the coating device 1 of the first embodiment, the pair of pressure rollers consisting of the upper roller 21 and lower roller 22 of the toner agglomeration section 20 simultaneously heats and pressurizes the printed layer of the paper sheet 2, agglomerating the toner and more reliably fixing it to the printed surface, thereby preventing the coating layer from peeling off after coating the paper sheet 2. On the other hand, in the coating device 1 of the first embodiment, fine streaks (ridges) may appear on the UV-coated paper sheet due to various factors such as the characteristics of the paper sheet 2 (thickness of the workpiece, etc.), the viscosity of the varnish, surface tension, and the transport speed of the paper sheet 2 (workpiece).

[0052] The inventors investigated the causes of ribbing on coated sheets by adjusting various parameters in the coating device 1 of the first embodiment. They found that, for example, ribbing does not occur when the coating is performed by applying pressure only in the toner agglomeration section 20 without heating the sheet 2. They also found that lowering the heating temperature of the sheet 2 in the toner agglomeration section 20 reduces the number and size of ribbing that occurs. From these results, the inventors discovered that the main cause of ribbing on UV-coated sheets is that the sheet 2 heated in the toner agglomeration section 20 enters the coating section 30 while still hot, and the UV varnish is applied to the hot sheet 2.

[0053] The coating apparatus 100 of the second embodiment is an improvement over the coating apparatus 1 of the first embodiment based on the above findings. In the coating apparatus 100 of the second embodiment, as described above, the printed surface of the paper sheet 2 heated in the toner aggregating section 20 is cooled by contact with the upper roller 71 in the workpiece cooling section 70 and further cooled by air blown onto it from the blower fan 76. The inventors performed a coating process using the coating apparatus 100 of the second embodiment on a paper sheet 2 that had developed ridges after coating using the coating apparatus 1 of the first embodiment, and confirmed that no ridges were formed on the paper sheet 2 after coating. Tests conducted by the inventors revealed that, although it depends on the paper sheet 2 and the configuration of the printed layer, in many cases, no ridges are formed on the paper sheet 2 if the temperature of the printed surface of the paper sheet 2 is cooled to, for example, about 60 to 70°C in the workpiece cooling section 70 before feeding it to the coating section 30.

[0054] The coating apparatus 1 of the above embodiment and the coating apparatus 100 of the second embodiment are both examples and can be modified as appropriate within the spirit of the present invention. In the above embodiment, a case where a coating process is performed on a paper sheet 2 has been described, but the coating process can be performed on the surface of not only paper sheets but also sheet-like paper or sheet-like objects other than paper. Furthermore, the coating process can be performed on the surface of not only sheet-like objects but also plate-like objects. Furthermore, the coating process can be performed using a liquid coating agent other than UV varnish.

[0055] While the above embodiment describes the coating process for a single-sided printed sheet 2, the present invention can also be used for double-sided printed sheets 2 (i.e., coating both the front and back surfaces of the sheet 2). In this case, it is preferable to use a material with a low coefficient of friction (e.g., 0.1 or less) (e.g., fluororesin) for the surfaces of both the upper roller 21 and the lower roller 22. Furthermore, when coating both surfaces, a mechanism for simultaneously coating both surfaces can be provided by providing varnish curing units 50 above and below the transport path, or by providing two varnish curing units 50 and a mechanism for inverting the top and bottom surfaces of the sheet 2 between them. Furthermore, in the second embodiment, it is preferable to use a material with at least high thermal conductivity for both the upper roller 71 and the lower roller 72 of the workpiece cooling unit 70.

[0056] In the above embodiment, the surfaces of the upper roller 21 and the resin film pressing first upper roller 52 are made of a material with a low coefficient of friction, but this is intended to prevent toner from being transferred from the printing surface, and other configurations may be used as long as this purpose is achieved. For example, upper and lower rollers made of rubber may be used, and an insert may be placed between the upper roller and the printing surface of the workpiece, such as the paper sheet 2, with the surface on the side that comes into contact with the printing surface made of a material with a low coefficient of friction (for example, 0.1 or less).

[0057] In the above embodiment, pressure roller pairs for heating and pressurizing the printed layer of the paper sheet 2 are provided in both the toner aggregation section 20 and the varnish curing section 50. However, they may be provided in only one of the sections. If pressure roller pairs are provided in only one of the sections, they should be located in a position where they can directly pressurize the printed layer, i.e., upstream of the area where the coating process is performed (coat section 30). In the above embodiment, the resin film pressing first upper roller 52 used in the varnish curing section 50 has a configuration similar to the upper roller 21 of the toner aggregation section 20. However, because the resin film pressing first upper roller 52 presses the printed layer of the paper sheet 2 via the resin film 58, there is no need to worry about toner adhesion, and the surface does not necessarily need to be made of a material with a low coefficient of friction.

[0058] In the above embodiment, the printing surface of the paper sheet 2 is simultaneously heated and pressurized using the halogen lamp 23 built into the upper roller 21 of the toner agglomeration unit 20 and the halogen lamp 57 built into the first upper resin film pressing roller 52 of the varnish curing unit 50. However, simultaneous heating and pressurization of the printing surface are not necessarily required. Specifically, for example, a separate heating unit may be provided upstream of the pressure roller pair that does not incorporate a heating unit, and the printing surface may be heated by the heating unit before being pressed. Furthermore, a heat source other than a halogen lamp may also be used. However, by incorporating a heating unit inside the roller to simultaneously pressurize and heat the printing surface, as in the above embodiment, the device can be made smaller and the toner can be effectively agglomerated and fixed to the printing surface.

[0059] In the above embodiment, the device is configured to coat the printed surface of a paper sheet 2 that has been printed by an electronic printer with UV varnish, but a similar configuration can also be used for devices that apply other types of coatings. For example, even in a device that applies a water-based coating to the printed surface of a workpiece, by using a configuration that pressurizes and heats the printed surface in the same way as above, the toner can be coagulated and fixed to the printed surface, preventing the coating layer and printed layer from peeling off.

[0060] In the above embodiment, the coating apparatus 1 is an integrated apparatus including both the toner aggregating unit 20 and the coater 30 and varnish curing unit 50. However, the coating apparatus 1 may also be an apparatus including the toner aggregating unit 20, coater 30, and varnish curing unit 50 separately. For example, if an existing coating apparatus exists, a toner aggregating unit having the toner aggregating unit 20 may be prepared separately from the existing coating apparatus, and the toner may be aggregating in the toner aggregating unit and fixed to the printing surface, and then the coating apparatus may apply the coating treatment. Alternatively, the toner may be aggregating in the toner aggregating unit and fixed to the printing surface after the coating treatment is performed in the coating apparatus. Furthermore, a coating system may be provided in which the toner aggregating unit having the toner aggregating unit 20 and the coating apparatus are separately provided, and the printing surface of the workpiece before and / or after the coating treatment is performed in the coating apparatus is heated and pressurized to aggregate the toner and fix it to the printing surface.

[0061] In the work cooling section 70 of the second embodiment, the paper sheets 2 are cooled using an upper roller 71 whose surface is made of a material with high thermal conductivity, and a blower fan 76, but the work cooling section 70 can be configured in any way that can cool the paper sheets 2 (such as a configuration in which cooling water is supplied to the inside of a metal roller with high thermal conductivity, such as aluminum).

[0062] Aspects It will be apparent to those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0063] (Item 1) A coating device according to one aspect of the present invention comprises a coating processing section that applies a predetermined coating process to the printed surface of a workpiece, which is a sheet-like or plate-like object having an electronic printing process applied to its surface; a pair of pressure rollers that are arranged upstream or downstream of the coating processing section and that sandwich and pressurize the workpiece while sending it out; and a heating section that is arranged at the same position as the pair of pressure rollers or further upstream in the conveying direction of the workpiece and that heats the printed surface of the workpiece.

[0064] (2) The coating device according to 2 is the coating device according to 1, wherein the heating section heats the printing surface of the workpiece simultaneously with the application of pressure by the pair of pressure rollers.

[0065] (Item 3) The coating device according to item 3 is the coating device according to either item 1 or 2, wherein the heating unit is built into the roller of the pair of pressure rollers that is positioned on the side of the printing surface.

[0066] (4) The coating device according to 4 is the coating device according to any one of 1 to 3, wherein the pair of pressure rollers is arranged upstream of the coating processing section, and the surface of the roller of the pair of pressure rollers that is positioned on the side that comes into contact with the printing surface is made of a material with a friction coefficient of 0.1 or less.

[0067] (Item 5) The coating device according to item 5 is the coating device according to any one of items 1 to 4, further comprising a work cooling unit provided between the pair of pressure rollers and the coating processing unit, for cooling the printing surface heated by the heating unit.

[0068] (Item 6) The coating device according to item 6 is the coating device according to item 5, wherein the work cooling section is provided with a pair of cooling rollers that sandwich and feed the work, and at least the surface of the roller that contacts the printing surface of the work is made of metal.

[0069] (7) The coating device according to 7 is the coating device according to 5 or 6, wherein the workpiece cooling section includes a blowing section that blows gas onto the printing surface of the workpiece.

[0070] (Item 8) The coating apparatus according to item 8 is the coating apparatus according to item 7, wherein the work cooling section further includes a rectifying section that is provided to surround the spraying section and that rectifies the flow of gas sprayed from the spraying section onto the work.

[0071] (Item 9) The coating device according to item 9 is the coating device according to any one of items 1 to 8, wherein the surface of the pressure roller pair that is positioned on the printing surface side is made of fluororesin. Note that the coating device according to item 5 also includes a coating device in which both surfaces of the pressure roller pair are made of fluororesin.

[0072] (Item 10) The coating device according to item 10 is the coating device according to any one of items 1 to 9, further comprising an insert member interposed between the printing surface and the roller of the pair of pressure rollers that is positioned on the printing surface side, the insert member having a surface that comes into contact with the printing surface made of a material with a friction coefficient of 0.1 or less.

[0073] (Item 11) A coating system according to one aspect of the present invention comprises a coating device equipped with a coating processing section that applies a predetermined coating process to the printed surface of a workpiece, which is a sheet-like or plate-like object having an electronic printing process applied to its surface; a pair of pressure rollers that sandwich and pressurize the workpiece before it is coated by the coating device and / or the workpiece after it has been coated by the coating device, and feeds it out; and a toner agglomeration device that is positioned at the same position as the pair of pressure rollers or upstream of them in the transport direction of the workpiece, and is equipped with a heating section that heats the printed surface of the workpiece.

[0074] DESCRIPTION OF SYMBOLS 1... Coating device 2... Sheet 10... Paper feed section 11... Accumulating section 12... Conveying mechanism 20... Toner aggregation section 21... Upper roller 211... Rubber roller 212... Fluorine resin tube 22... Lower roller 23... Halogen lamp 30... Coating section 31... Upper roller 32... Lower roller 33... Doctor blade 34... Varnish reservoir 35... Varnish supply section 40... Conveying section 41... Conveying table 42... Belt 50... Varnish curing section 51... Resin film supply roller 52... Resin film pressing first upper roller 521... Rubber roller 522... Fluorine resin tube 53... Resin film pressing first lower roller 54... Resin film pressing second roller 55... Resin film recovery roller 56... UV light source 57... Halogen lamp 58... Resin film 60... Accumulating section 70... Work cooling section 71... Upper roller 72... Lower roller 73: First gear 74: Second gear 75: Motor 751: Gear 76: Blower fan 77: Ventilation guide 80: Control unit 81: Storage unit 82: Input unit 83: Display unit

Claims

1. a coating processing unit that applies a coating process using a liquid coating agent to a printed surface of a workpiece, which is a sheet-like or plate-like object having a surface subjected to an electronic printing process; a pair of pressure rollers arranged on the upstream side or downstream side of the coating processing unit, which sandwich the workpiece and pressurize it while sending it out; a heating unit that is arranged at the same position as the pair of pressure rollers or on the upstream side thereof in the conveying direction of the workpiece and heats the printing surface of the workpiece; A coating apparatus comprising:

2. The heating unit heats the printing surface of the workpiece simultaneously with the pressure applied by the pressure roller pair.

2. The coating apparatus according to claim 1.

3. The heating unit is built into the roller of the pair of pressure rollers that is disposed on the printing surface side.

2. The coating apparatus according to claim 1.

4. The pressure roller pair is disposed upstream of the coating processing unit, The surface of the pressure roller pair that is positioned on the side that comes into contact with the printing surface is made of a material with a friction coefficient of 0.1 or less.

2. The coating apparatus according to claim 1.

5. moreover, a workpiece cooling section provided between the pair of pressure rollers and the coating processing section, which cools the printing surface heated by the heating section; 5. The coating apparatus according to claim 4, further comprising:

6. The workpiece cooling unit includes a pair of cooling rollers that sandwich and send out the workpiece, and at least the surface of the roller that contacts the printing surface of the workpiece is made of metal.

6. The coating apparatus according to claim 5.

7. 6. The coating apparatus according to claim 5, wherein the workpiece cooling section includes a blowing section that blows gas onto the printing surface of the workpiece.

8. 8. The coating apparatus according to claim 7, wherein the workpiece cooling section further comprises a rectifying section that is provided to surround the spray section and that rectifies the flow of gas sprayed from the spray section onto the workpiece.

9. The surface of the pressure roller pair disposed on the printing surface side is made of fluororesin.

2. The coating apparatus according to claim 1.

10. an inserting member that is interposed between the printing surface and the roller of the pair of pressure rollers that is positioned on the printing surface side, and the surface that comes into contact with the printing surface is made of a material with a friction coefficient of 0.1 or less; The coating apparatus according to claim 1, further comprising:

11. a coating device including a coating processing unit that applies a coating process using a liquid coating agent to a printed surface of a workpiece, which is a sheet-like or plate-like object having an electronic printing process applied to its surface; a toner agglomeration device including a pair of pressure rollers that sandwich and pressurize the work before it is coated by the coating device and / or the work after it has been coated by the coating device, and a heating unit that is disposed at the same position as the pair of pressure rollers or upstream thereof in the conveying direction of the work, and that heats the printing surface of the work; A coating system comprising: