Printing device and inkjet printing method

Abstract

To perform high-quality printing by sufficiently drying the ink fixed on a printed material with an upstream side inkjet head while preventing the condensation of a downstream side inkjet head.SOLUTION: Between upstream-side inkjet heads 5a,5b and downstream-side inkjet heads 5c,5d, provided is a heating plate 11 to heat and dry a printing sheet P from its back side, with its front side subjected to printing with the upstream-side inkjet heads 5a,5b. Between the heating plate 11 and the downstream-side inkjet heads 5c,5d, provided is a cooling plate 16 to cool the printing sheet P heated with the heating plate 11 from its back side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an inkjet printing apparatus and printing method, and more particularly to an inkjet printing apparatus and printing method which perform printing and drying in parallel. [Background technology]

[0002] Conventionally, a printing device has been known that includes an unwinding section that unwinds the substrate to be printed, a winding section that winds up the substrate to be printed unwound from the unwinding section, and multiple inkjet heads that print on the front side of the substrate to be printed unwound from the unwinding section, in which the multiple inkjet heads are divided into two groups and the substrate to be printed is heated between the two groups.

[0003] For example, as disclosed in Patent Document 1, a drying system is known which includes a first drying device that dries a first liquid that has adhered to an object to be adhered to, and a second drying device that dries a second liquid containing a conductor that has adhered to the object to be adhered to after the first drying device has dried the first liquid, and the first drying device is a dielectric heating device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6657946 Summary of the Invention [Problem to be solved by the invention]

[0005] In a drying system such as that described in Patent Document 1, when the substrate is heated by the first drying device, a temperature difference occurs between the substrate and the inkjet head that sprays the second liquid, resulting in the problem that the inkjet head that sprays the second liquid causes condensation due to the first liquid adhering to the substrate or moisture in the air.

[0006] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to enable printing with good print quality by preventing condensation on the downstream inkjet head while thoroughly drying ink deposited by the upstream inkjet head. [Means for solving the problem]

[0007] In order to achieve the above object, in the present invention, the printing material is forcibly cooled immediately after being heated, thereby preventing condensation on the downstream ink-jet head.

[0008] Specifically, in the first invention, An unwinding section that unwinds the printed material; a winding section that winds up the printing material unwound from the unwinding section; A plurality of inkjet heads for printing on the front side of the printing medium unwound from the unwinding section; a heating section provided between the upstream inkjet head and the downstream inkjet head, for heating and drying a substrate printed on a front side by the upstream inkjet head from a rear side of the substrate; A cooling section is provided between the heating section and the downstream inkjet head, and cools the printing substrate heated by the heating section from the back side of the printing substrate.

[0009] According to the above configuration, the ink from the upstream inkjet head is heated and evaporated in the heating section, and then immediately cooled in the cooling section, so that the temperature difference between the upstream inkjet head and the downstream inkjet head is reduced, and condensation does not form on the downstream inkjet head. In addition, since the printing material is forcibly cooled, there is no need to ensure a long transport distance to cool the heated printing material.

[0010] In the second invention, in the first invention, A first temperature sensor provided between the heating unit and the cooling unit; A second temperature sensor provided behind the cooling unit; and a control device that adjusts the temperatures of the heating section and the cooling section based on the temperatures detected by the first temperature sensor and the second temperature sensor, respectively.

[0011] According to the above configuration, the first temperature sensor can detect the degree of heating by the heating section, and the second temperature sensor can detect the degree of cooling by the cooling section, so that optimal temperature adjustment can be performed in real time, thereby more reliably preventing condensation on the downstream inkjet head.

[0012] In a third aspect of the present invention, in the first or second aspect of the present invention, the heating unit comprises a heating plate that heats the printing substrate while being in contact with the back side of the printing substrate, The cooling section comprises a cooling plate that cools the printing substrate while being in contact with the back side of the printing substrate.

[0013] According to the above configuration, the heating plate can efficiently heat the substrate while contacting the back surface of the substrate. Also, the cooling plate can efficiently cool the substrate while contacting the back surface of the substrate. Furthermore, because it is a contact type plate, it is difficult for mutual interference and adverse effects to occur, as occurs with hot and cold air.

[0014] A fourth aspect of the present invention provides a printing device characterized in that an influence suppression section for suppressing the influence between the heating section and the cooling section is provided between the heating section and the cooling section.

[0015] According to the above configuration, the influence between the heating section and the cooling section can be suppressed, so that, for example, it is possible to suppress the heating section from adversely affecting the cooling section, or the cooling section from adversely affecting the heating section.

[0016] In a fifth aspect of the present invention, the influence suppression unit is a printing device that is a blower or suction device for creating an air flow in the heating unit and the cooling unit.

[0017] According to the above configuration, by creating an air flow between the heating section and the cooling section, it is easy to suppress the influence between them.

[0018] In a sixth aspect of the present invention, the influence suppression unit is a printing device that is a partition that isolates the heating unit from the cooling unit.

[0019] According to the above configuration, the influence between the heating section and the cooling section can be physically blocked by the partition wall, so that it is easy to suppress the influence between the two.

[0020] In the seventh invention, an unwinding process for unwinding the printed material; an upstream printing step of printing on a front side of the printing medium unwound from the unwinding section by an upstream inkjet head; a heating step of heating a printed material, the surface of which has been printed by the upstream inkjet head, from a back side of the printed material by a heating unit; a cooling step of cooling the heated printing substrate by a cooling section immediately after the heating step; a downstream printing step of printing the printing substrate by a downstream inkjet head after the cooling step; and a winding step of winding up the printed material that has been subjected to the downstream printing step.

[0021] According to the above configuration, the ink from the upstream inkjet head is heated and evaporated in the heating section, and then immediately cooled in the cooling section, so that the temperature difference between the upstream inkjet head and the downstream inkjet head is reduced, and condensation does not form on the downstream inkjet head. In addition, since the printing material is forcibly cooled, there is no need to ensure a long transport distance to cool the heated printing material.

[0022] In an eighth aspect of the present invention, in the seventh aspect of the present invention, a first measuring step of measuring the temperature of the printing substrate heated in the heating step; A second measuring step of measuring the temperature of the printing substrate cooled in the cooling step; and a temperature adjusting step of adjusting the temperatures of the heating unit and the cooling unit, respectively, based on the temperatures obtained in the first measuring step and the second measuring step.

[0023] According to the above configuration, the degree of heating by the heating section can be detected by the first measurement process, and the degree of cooling by the cooling section can be detected by the second measurement process, so that optimal temperature adjustment can be performed in real time, thereby more reliably preventing condensation on the downstream inkjet head. Effect of the Invention

[0024] As described above, according to the present invention, by preventing condensation on the downstream inkjet head while sufficiently drying the ink deposited by the upstream inkjet head, it is possible to perform printing with good print quality. [Brief description of the drawings]

[0025] [Figure 1] 1 is a front view showing an outline of a printing device according to a first embodiment of the present invention. [Diagram 2] FIG. 11 is a front view showing an outline of a printing device according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a front view showing an outline of a printing device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] [First embodiment] A first embodiment to which the present invention is applied will be described below with reference to FIG.

[0027] 1 shows an inkjet printing device 1 according to an embodiment of the present invention, and this printing device 1 is equipped with an unwinding section 2 that unwinds printing paper P as a printing substrate. This unwinding section 2 is configured to rotatably support a roll of printing paper P. The printing paper P is made of, for example, a paper material, but various films that can be printed with ink may also be used as the printing substrate.

[0028] The printing device 1 also includes a winding section 3 on the most downstream side that winds up the printing paper P unwound from the unwinding section 2. The unwinding section 2 is adapted to rotatably mount a roll of unprinted paper. The winding section 3 is driven, for example, by a drive device such as an electric motor (not shown) so that the printing paper is transported at a speed of, for example, 10 to 100 m / min. Although the illustration in FIG. 1 is simplified, in reality, the printing paper P unwound from the unwinding section 2 is guided by a number of guide rollers that are appropriately provided and wound up by the winding section 3. The printing paper wound up by the winding section 3 is taken out as a single roll.

[0029] Although not shown in FIG. 1, the printing paper P unwound from the unwinding section 2 may be corona-treated by a known corona treatment device.

[0030] Furthermore, the printing paper P that has been subjected to the corona treatment may be subjected to a preheat treatment in a preheat section (not shown).

[0031] The printing paper P is guided by a guide roller (not shown) and printed by the inkjet heads 5a and 5b on the most upstream side and the inkjet heads 5c and 5d on the downstream side in an inkjet system. The number and arrangement of the inkjet heads are not particularly limited. In this embodiment, two inkjet heads of each of four colors are arranged, but they may be arranged separately on the upstream side with one and three, or three and one, or five or more inkjet heads may be appropriately divided between the upstream side and the downstream side.

[0032] The printing device 1 is adapted to be heated by an inter-inkjet drying section 10 that heats the printing paper P whose obverse side has been printed by the upstream inkjet heads 5a, 5b.

[0033] The inter-inkjet drying section 10 is equipped with a heating plate 11 as a heating section that contacts and heats the back side of the printing paper P. The heating plate 11 is made of, for example, a metal plate equipped with an internal water jacket, and a heat medium made of water, oil, etc. heated by a temperature regulator 12 is circulated. The heating plate 11 itself is configured to be able to be heated to approximately 30 to 100°C by this heat medium.

[0034] The heating section may use other heating methods such as heating with a heater including an electric heating wire, heating by electromagnetic waves, or infrared heating with mid-infrared rays (MIR) of about 2.5 to 4 μm.

[0035] The inter-inkjet drying section 10 may further include a dryer 14 that dries the printing paper P from above. The dryer 14 is not particularly limited to a specific type, such as hot air drying, but it assists the drying by the heating plate 11, and for example, has an outlet 13 provided above the heating plate 11 and is capable of discharging air containing ink vapor from an outlet 15 provided at a position away from the outlet 13. By not only heating and drying the printing paper P with the heating plate 11, but also heating and discharging it with the inter-inkjet drying section 10, the ink is dried more efficiently.

[0036] As a feature of this embodiment, a cooling plate 16 is provided between the heating plate 11 and the downstream inkjet heads 5c, 5d as a cooling section that cools the back side of the printing paper P heated by the heating plate 11. The cooling plate 16 is made of, for example, a metal plate equipped with an internal water jacket, and a heat medium made of water, oil, or the like cooled by a chiller 17 circulates through the cooling plate 16. This heat medium allows the cooling to a temperature of 15°C or higher and 35°C or lower by the cooling plate 16.

[0037] The cooling section may use other cooling methods such as blowing cold air from the front side of the printing paper P.

[0038] A first temperature sensor 18, for example an infrared temperature sensor, is provided between the heating plate 11 and the cooling plate 16. This first temperature sensor 18 is capable of measuring the temperature of the printing paper P heated by the heating plate 11 from the rear surface.

[0039] A second temperature sensor 19, for example an infrared temperature sensor, is provided behind the cooling plate 16. This second temperature sensor 19 is capable of measuring the temperature of the printing paper P heated by the cooling plate 16 from the front side. Note that the second temperature sensor 19 may also be capable of measuring the temperature of the printing paper P from the rear side.

[0040] The detection values ​​of the first temperature sensor 18 and the second temperature sensor 19 are transmitted to the control device 20, which controls the temperature regulator 12 and the chiller 17 to adjust the temperatures of the heating plate 11 and the cooling plate 16, respectively.

[0041] For example, if the transport distance between the upstream inkjet heads 5a, 5b and the downstream inkjet heads 5c, 5d is 750 mm, the heating plate 11 is 260 mm and the cooling plate is 260 mm, a gap of 75 mm may be provided between the upstream inkjet and the downstream inkjet, and a gap of 80 mm may be provided between the heating plate 11 and the cooling plate 16. In this way, the space for the inter-inkjet drying section 10 is kept to a minimum.

[0042] A heating roll 21 is provided on the most downstream side for heating and drying the printing paper P printed by the inkjet heads 5a to 5d. The heating roll 21 has an outer diameter of, for example, about 600 mm, is heated to about 30 to 100°C, and serves to heat the wrapped printing paper P and dry the ink.

[0043] -Inkjet printing method- A method for performing inkjet printing on printing paper P using the above-mentioned printing device 1 will be described.

[0044] First, in the unwinding process, the printing paper P is unwound. This is started in the winding process by driving the drive device to wind up the printing paper P. For example, when the amount of ink applied is 10 g / m in a wet state, 2 At this time, the conveying speed is approximately 50 m / min.

[0045] Next, in a corona treatment step, corona treatment is performed on the surface of the printing paper P. This corona treatment may be omitted.

[0046] Next, in a preheating step, the printing paper P may be dried in advance to a moisture content lower than the normal moisture content.

[0047] Next, in the upstream printing process, a predetermined ink (for example, black, cyan) is applied to the printing paper P by the inkjet heads 5a and 5b.

[0048] Next, in a heating step, the printing paper P printed by the upstream inkjet heads 5a, 5b is heated from the back side by the heating plate 11 to, for example, 70°C to 80°C. In this heating step, the printing paper P is additionally heated by the dryer 14, and evaporated steam is exhausted. In a first measurement step, the temperature of the printing paper P after heating is measured from the back side by the first temperature sensor 18, and the measurement result is sent to the control device 20. If the measurement result is too high or too low, the control device 20 may automatically adjust the temperature of the heat medium of the temperature regulator 12.

[0049] Then, in a cooling step immediately after the heating step, the heated printing paper P is cooled to 15° C. or higher and 35° C. or lower by the cooling plate 16. In a second measurement step, the temperature of the cooled printing paper P is measured from the front side by the second temperature sensor 19, and the measurement result is sent to the control device 20. The control device 20 may automatically adjust the temperature of the heat medium of the chiller 17 if the measurement result is too high or too low.

[0050] Next, the downstream inkjet heads 5c, 5d print, for example, magenta and yellow on the front side of the printing paper P. At this time, since the printing paper P has already been cooled to 15°C or more and 35°C or less by the cooling plate 16, no condensation occurs on the downstream inkjet heads 5c, 5d. Also, since the ink ejected from the upstream inkjet heads 5a, 5b has already been sufficiently dried in the heating process, the ink ejected from the downstream inkjet heads 5c, 5d does not mix or bleed on the printing paper P.

[0051] Then, in the final drying step, the paper is heated to about 60° C. on the outer periphery of the heat roll 21. As a result, the ink on the printing paper P is almost completely dried.

[0052] Then, in the winding process, the printing paper P is wound onto the winding section 3 with the ink being sufficiently dry. In this embodiment, the printing surface that is not sufficiently dry does not come into contact with the roller, so the roller does not get dirty and a clean finished print is produced.

[0053] In this embodiment, since the heated print paper P is forcibly cooled just before the downstream inkjet heads 5c and 5d, there is no need to ensure a long transport distance for cooling the heated print paper P.

[0054] Furthermore, since the first temperature sensor 18 can detect the degree of heating by the heating plate 11 and the second temperature sensor 19 can detect the degree of cooling by the cooling plate 16, optimal temperature adjustment can be performed in real time, thereby more reliably preventing condensation on the downstream inkjet heads 5c, 5d.

[0055] The partition 24 and the blower 22 may be provided separately or in combination on the printing device 1. Either may be selected as appropriate.

[0056] Therefore, according to the printing device 1 of this embodiment, it is possible to perform printing with good print quality by preventing condensation on the downstream inkjet heads 5c and 5d while thoroughly drying the ink deposited by the upstream inkjet heads 5a and 5b. [Second embodiment]

[0057] A second embodiment of the present invention will now be described with reference to FIG. In addition, since this embodiment has a configuration in which a blower device serving as an influence suppression section is added to the first embodiment, the same components are given the same reference numerals and the description thereof will not be repeated.

[0058] As shown in Fig. 2, in this embodiment, an air blower 22 is provided between the heating plate 11 and the cooling plate 16. Examples of the air blower 22 include an air fan and an air blower. The air blower 22 generates an air flow in a wind direction 23 between the heating plate 11 and the cooling plate 16, thereby preventing the air heated by the heating plate 11 from adversely affecting the cooling plate 16 and the air cooled by the cooling plate 16 from adversely affecting the heating plate 11. Specifically, the air heated by the heating plate 11 is rapidly cooled by the cooling plate 16, which can prevent adverse effects such as condensation on the temperature sensor 18, the cooling plate 16, the printing paper P, and other devices. [Third embodiment]

[0059] A third embodiment of the present invention will now be described with reference to FIG. In addition, since this embodiment has a configuration in which a partition wall serving as an influence suppression portion is added to the first embodiment, the same components are given the same reference numerals and the description thereof will not be repeated.

[0060] As shown in Fig. 3, in this embodiment, a partition wall 24 is provided between the heating plate 11 and the cooling plate 16. Examples of the partition wall 24 include a plastic plate, an air cushion sheet, an aluminum alloy plate, a concrete plate, a glass plate, and a plaster board. The partition wall 24 physically isolates the heating plate 11 from the cooling plate 16, thereby preventing the air heated by the heating plate 11 from adversely affecting the cooling plate 16 and the air cooled by the cooling plate 16 from adversely affecting the heating plate 11. Specifically, it is possible to prevent adverse effects such as condensation on the temperature sensor 18, the cooling plate 16, the printing paper P, and other devices caused by the air heated by the heating plate 11 being rapidly cooled by the cooling plate 16.

[0061] (Other embodiments) The present invention may have the following configurations with respect to the above first to third embodiments.

[0062] That is, the printing paper P may be brought into close contact with the heating plate 11 and the cooling plate 16 by a method such as electrostatic charging or suction, so as to facilitate the transfer of temperature.

[0063] In addition, in the above embodiment, two of each of the four color inkjet heads 5a, 5b, 5c, and 5d are arranged, and a heating plate 11 and a cooling plate 16 are arranged between them, but a heating plate 11 and a cooling plate 16 may also be arranged between each of the inkjet heads 5a, 5b, 5c, and 5d.

[0064] Depending on the application, the inkjet head may be separated into inkjet head 5a and inkjet heads 5b, 5c, and 5d, and the heating plate 11 and cooling plate 16 may be disposed between inkjet head 5a and inkjet heads 5b, 5c, and 5d, or the inkjet head may be disposed in the following order: inkjet head 5a-heating plate 11 and cooling plate 16-inkjet heads 5b and 5c-heating plate 11 and cooling plate 16-inkjet head 5d. Furthermore, five or more sets of inkjet heads may be provided. In short, any configuration may be used as long as the heating plate 11 and cooling plate 16 are disposed between the upstream inkjet head and the downstream inkjet head.

[0065] In the second embodiment, the blower 22 is used as the influence suppression unit, but a suction device may be used. In short, there is no particular limitation as long as the configuration can suppress the air heated by the heating plate 11 from adversely affecting the cooling plate 16 and the air cooled by the cooling plate 16 from adversely affecting the heating plate 11 by generating an air flow of the air flow direction 23 between the heating plate 11 and the cooling plate 16. In addition, there is no particular limitation as to the wind direction of the air flow as long as it produces such an effect. In addition, the configuration may be such that the wind direction and the strength of the air flow can be changed and adjusted.

[0066] Moreover, the blower 22 and the partition wall 24 may be used in combination as the influence suppression section.

[0067] It should be noted that the above-described embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its applications, or uses. [Explanation of symbols]

[0068] 1 Printing device 2 Unwinding section 3 Winding section 5a, 5b Upstream inkjet head 5c, 5d Downstream inkjet head 10 Inkjet Drying Section 11 Heating plate 12 Temperature controller 13 Outlet 14 Dryer 15 Outlet 16 Cooling plate 17 Chiller 18 First temperature sensor 19 Second temperature sensor 20 Control device 21 Heat roll 22 Blower 23 Wind direction 24 Bulkhead

Claims

1. An unwinding section that unwinds the printed material; a winding section that winds up the printing material unwound from the unwinding section; A plurality of inkjet heads for printing on the front side of the printing medium unwound from the unwinding section; a heating section provided between the upstream inkjet head and the downstream inkjet head, for heating and drying a substrate printed on a front side by the upstream inkjet head from a rear side of the substrate; a cooling section provided between the heating section and the downstream inkjet head, for cooling the printing substrate heated by the heating section from the back surface side of the printing substrate; the heating unit comprises a heating plate that heats the printing substrate while being in contact with the back side of the printing substrate, The cooling unit is a cooling plate that cools the printing substrate while contacting the back side of the printing substrate. A printing device comprising:

2. 2. The printing device according to claim 1, A first temperature sensor provided between the heating unit and the cooling unit; A second temperature sensor provided behind the cooling unit; a control device that adjusts the temperatures of the heating unit and the cooling unit based on the temperatures detected by the first temperature sensor and the second temperature sensor, respectively. A printing device comprising:

3. In the printing device according to claim 1 or 2, a heat exchanger for exchanging heat with said cooling unit; and a heat exchanger for exchanging heat with said heating unit.

4. In the printing device according to claim 3, A printing apparatus in which the influence suppression unit is a blower or suction unit for creating an air flow between the heating unit and the cooling unit.

5. In the printing device according to claim 3, A printing apparatus, wherein the influence suppression unit is a partition that isolates the heating unit from the cooling unit.

6. an unwinding process for unwinding the printed material; an upstream printing step of printing on the front side of the printing medium unwound in the unwinding step by an upstream inkjet head; a heating step of heating the printed material, the surface of which has been printed by the upstream inkjet head, from the back side of the printed material by a heating unit having a heating plate that heats the printed material while being in contact with the back side of the printed material; a cooling step of cooling the heated printing substrate by a cooling unit including a cooling plate that cools the printing substrate while contacting the back side of the printing substrate immediately after the heating step; a downstream printing step of printing the printing substrate by a downstream inkjet head after the cooling step; and a winding step of winding up the printed material that has been subjected to the downstream printing step.

1. A method for ink-jet printing comprising the steps of:

7. 7. The inkjet printing method of claim 6, a first measuring step of measuring the temperature of the printing substrate heated in the heating step; a second measuring step of measuring the temperature of the printing substrate cooled in the cooling step; and a temperature adjustment step of adjusting the temperatures of the heating unit and the cooling unit based on the temperatures obtained in the first measurement step and the second measurement step.

1. A method for ink-jet printing comprising the steps of:

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