Drying device and liquid ejection device

Abstract

To solve a suction failure of a sheet.SOLUTION: A drying device includes: an endless conveyance belt 18 that conveys a sheet S; sucking means 30 that sucks the sheet S to the conveyance belt 18; and drying means 23 disposed to face a sheet sucking surface 18b of the conveyance belt 18 and drying the sheet S. The sucking means 30 includes a plurality of suction members 31 arranged side by side in a sheet conveyance direction A inside the conveyance belt 18. A suction force of at least one suction member 31 of the plurality of suction members 31 is different from suction forces of the other suction members 31.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a drying device and a liquid ejection device. [Background technology]

[0002] 2. Description of the Related Art As an example of a liquid ejection device, an inkjet type image forming device that ejects ink onto a sheet to form an image is known.

[0003] Some of such image forming apparatuses are provided with a drying device that dries the ink ejected onto the sheet.

[0004] For example, Patent Document 1 (JP 2014-181130 A) proposes a technology in which a sheet onto which ink has been ejected is adsorbed and transported by a guide plate or a transport belt, and the ink is dried by irradiating the sheet with infrared light or blowing dry air onto it.

[0005] However, in a configuration in which a sheet is attracted and conveyed, there are cases in which the sheet cannot be attracted and conveyed satisfactorily. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to improve the poor sheet adsorption. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a drying device comprising an endless conveying belt for conveying a sheet, an adsorption means for adsorbing the sheet to the conveying belt, and a drying means arranged opposite the sheet adsorption surface of the conveying belt for drying the sheet, wherein the adsorption means comprises a plurality of suction members arranged in a line in the sheet conveying direction inside the conveying belt, and the suction force of at least one of the plurality of suction members is different from the suction force of the other suction members. Effect of the Invention

[0008] According to the present invention, the sheet can be adsorbed and transported satisfactorily. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of a liquid ejection apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a control unit according to the first embodiment of the present invention. [Diagram 3] FIG. 1 is a side view of a drying device according to a first embodiment of the present invention. [Figure 4] 1 is a plan view of a drying device according to a first embodiment of the present invention. [Diagram 5] 1 is a diagram showing a configuration of a characteristic part of a drying device according to a first embodiment of the present invention; [Figure 6] FIG. 4 is a diagram showing a configuration of a characteristic part of a drying device according to a second embodiment of the present invention. [Figure 7] 13A and 13B are diagrams illustrating an embodiment in which a second suction member moves together with a downstream support roller. [Figure 8] 6A to 6C are diagrams illustrating a configuration of a second suction member. [Figure 9] 11 is a diagram for explaining an arrangement of a second suction member and a negative pressure generating means. FIG. [Figure 10] FIG. 11 is a diagram showing a configuration of a characteristic part of a drying device according to a third embodiment of the present invention. [Figure 11] FIG. 13 is a diagram for explaining the direction in which the air outlet faces. [Figure 12] FIG. 11 is a block diagram showing a configuration of a control unit according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a diagram illustrating an example of a control flow for controlling an air volume. [Figure 14] FIG. 2 is a perspective view of an ultraviolet ray irradiation unit which is an example of a drying unit. [Figure 15] FIG. 1 is a reference diagram for explaining a problem with a drying device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below with reference to the attached drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are given the same reference numerals as far as they can be distinguished, and the description will be omitted after it has been explained once. In the following description, "image formation", "recording", and "printing" are all synonymous.

[0011] <Configuration of Liquid Ejection Apparatus> First, the configuration of a liquid ejection device according to a first embodiment of the present invention will be described with reference to FIG.

[0012] 1, an inkjet type image forming apparatus is taken as an example of a liquid ejection apparatus 100 according to a first embodiment of the present invention. The liquid ejection apparatus 100 shown in FIG. 1 includes a sheet supply section 1, an image forming section 2, a drying section 3, a sheet ejection section 4, and a reversing conveying section 5.

[0013] The sheet supply unit 1 is a section that supplies sheets S as recording media on which an image is formed. The sheet supply unit 1 includes a supply tray 11 that can store a plurality of sheets S, and a feeding device 12 that separates and feeds the sheets S one by one from the supply tray 11. The sheets S fed by the feeding device 12 are supplied to the image forming unit 2.

[0014] The image forming section 2 is a section that forms an image on the sheet S. The image forming section 2 includes a liquid ejection section 13, a first carrying rotor 14, a second carrying rotor 15, and a third carrying rotor 16. The first carrying rotor 14, the second carrying rotor 15, and the third carrying rotor 16 are rotors that carry the sheet S on their outer circumferential surfaces and rotate to transport the sheet S. The sheet S transported from the sheet supply section 1 is carried on the first carrying rotor 14 and transferred to the second carrying rotor 15. The sheet S transferred to the second carrying rotor 15 is then transferred from the second carrying rotor 15 to the third carrying rotor 16. The liquid ejection section 13 includes a plurality of liquid ejection units 13C, 13M, 13Y, 13K, and 13W that eject liquid ink onto the sheet S carried on the second carrying rotor 15. In this embodiment, the liquid ejection unit 13C for cyan ink, the liquid ejection unit 13M for magenta ink, the liquid ejection unit 13Y for yellow ink, the liquid ejection unit 13K for black ink, and the liquid ejection unit 13W for white ink are arranged in this order from the upstream side in the rotation direction of the second carrying rotor 15 (the conveying direction of the sheet S). The arrangement of the liquid ejection units 13C, 13M, 13Y, 13K, and 13W is not limited to the order shown in FIG. 1, and may be in any order. In addition, the colors of ink used in each liquid ejection unit are not limited to cyan, magenta, yellow, black, and white. If necessary, a liquid ejection unit that ejects ink of other special colors such as white, gold, and silver in addition to white may be added.

[0015] When the sheet S is conveyed to a position facing each of the liquid ejection units 13C, 13M, 13Y, 13K, and 13W, ink is ejected from each of the liquid ejection units 13C, 13M, 13Y, 13K, and 13W onto the sheet S to form an image. Image formation is not limited to forming a full-color image using all of the liquid ejection units 13C, 13M, 13Y, 13K, and 13W, but it is also possible to form a monochromatic image using any one of the liquid ejection units 13C, 13M, 13Y, 13K, and 13W, or to form a two-color or three-color image using any two or three of the imaging units.

[0016] The drying section 3 is a section that dries the ink ejected onto the sheet S. The drying section 3 includes a drying device 10 that includes a drying means 23, a conveyor belt 18, and a sheet detection means 19. The drying means 23 is a means for drying the sheet S. In this embodiment, an ultraviolet irradiation means that irradiates ultraviolet rays toward the conveyed sheet S is used as the drying means 23. When ultraviolet rays are irradiated onto the ink on the sheet S, a coloring material such as a pigment or dye contained in the ink absorbs the ultraviolet rays and converts them into thermal energy, thereby generating heat. This causes the temperature of the ink to rise, and the water or organic solvent in the ink evaporates, causing the ink to dry. Alternatively, an infrared irradiation means that irradiates infrared rays onto the sheet S, or an air blowing means that blows air onto the sheet S may be used as the drying means 23. The sheet detection means 19 is a means for detecting the sheet S upstream of the drying means 23 in the conveying direction of the sheet S (hereinafter referred to as the "sheet conveying direction"). In this embodiment, the sheet detection means 19 is disposed downstream in the sheet conveying direction from the liquid discharger 13 and upstream in the sheet conveying direction from the third support rotor 16. As the sheet detection means 19, it is preferable to use a reflective or transmissive non-contact sensor.

[0017] When the sheet S is transported by the transport belt 18 to a position facing the drying means 23, the drying process of the sheet S is performed by the drying means 23. In this embodiment, the ink on the sheet S is dried by irradiating the sheet S with ultraviolet rays from the ultraviolet irradiating means. The timing at which the sheet S is irradiated with ultraviolet rays is determined based on the timing at which the sheet detection means 19 detects the sheet S and the transport speed of the sheet S.

[0018] The sheet discharge section 4 is a section where the sheet S is discharged. The sheet discharge section 4 includes a discharge tray 20. When the sheet S is conveyed from the drying section 3 to the sheet discharge section 4, the sheet S is discharged onto the discharge tray 20.

[0019] The reverse conveying section 5 is a section that reverses the sheet S and conveys it again to the image forming section 2 when double-sided printing is performed. The reverse conveying section 5 is composed of a switchback conveying section 21 and a return conveying section 22. When double-sided printing is performed, an image is formed on the first surface (front surface) of the sheet S in the image forming section 2, and after the image on the first surface is dried in the drying section 3, the sheet S is conveyed to the reverse conveying section 5 without being conveyed to the sheet discharge section 4. Then, the sheet S is first conveyed in the reverse direction in the switchback conveying section 21 of the reverse conveying section 5, and then conveyed to the upstream side of the first support rotor 14 through the return conveying section 22. As a result, the sheet S is supplied to the image forming section 2 in a reversed state. Then, after an image is formed on the second surface (reverse surface) of the sheet S opposite to the first surface in the image forming section 2, the image on the second surface is dried in the drying section 3, and the sheet S is conveyed to the sheet discharge section 4.

[0020] <Control Unit Configuration> FIG. 2 is a block diagram showing the configuration of a control unit according to the first embodiment of the present invention.

[0021] 2, the liquid ejection device 100 includes a control unit 200 that controls various operations such as a sheet conveying operation, an image forming operation, a drying operation, etc. Specifically, the control unit 200 includes a main control unit 201, an image input unit 202, a droplet adhesion amount calculation unit 203, a speed setting unit 204, a sheet information input unit 205, a liquid ejection control unit 207, a conveyance control unit 208, and a drying control unit 209.

[0022] The main control unit 201 is composed of a CPU (Central Processing Unit) that controls the operation of the entire liquid ejection device 100, a ROM (Read Only Memory) that stores programs executed by the CPU and other fixed data, a RAM (Random Access Memory) that temporarily stores image information, and a rewritable NVRAM (Non-Volatile Random Access Memory) that retains data even when the power to the liquid ejection device 100 is cut off.

[0023] When the sheet speed is set by the speed setting unit 204, the main control unit 201 transmits a control signal to the conveyance control unit 208 based on the information of the set speed. The conveyance control unit 208 receives the control signal from the main control unit 201 and controls the conveyance operation of the conveyance unit 400. As a result, the sheet is conveyed at the set speed. The conveyance unit 400 includes the feeding device 12 of the sheet supply unit 1, the supporting rotors 14, 15, and 16 of the image forming unit 2, the conveyance belt 18 of the drying unit 3, the switchback conveyance unit 21 and the return conveyance unit 22 of the reverse conveyance unit 5, and the like.

[0024] Furthermore, when print image information is input to the image input unit 202, the main control unit 201 transmits a control signal to the liquid ejection control unit 207 based on the input image information. The liquid ejection control unit 207 receives the control signal from the main control unit 201 and controls the ejection operation of the liquid ejection unit 13. This causes liquid to be ejected from the liquid ejection unit 13, and an image according to the image information is formed on the sheet.

[0025] The image information input to the image input unit 202 is sent to the main control unit 201 as well as to the droplet adhesion amount calculation unit 203. The droplet adhesion amount calculation unit 203 calculates the droplet adhesion amount of liquid required for image formation based on the image information from the image input unit 202. The main control unit 201 transmits a control signal to the drying control unit 209 based on the droplet adhesion amount obtained from the droplet adhesion amount calculation unit 203 and the sheet information obtained from the sheet information input unit 205. The drying control unit 209 receives the control signal from the main control unit 201 and controls the drying strength of the drying means 23. For example, in this embodiment, the output strength of the ultraviolet light irradiated from the ultraviolet light irradiation means is controlled. The amount of heat and time required to dry the ink differs depending on the amount of ink ejected onto the sheet S or the surface material of the sheet. For this reason, based on the droplet adhesion amount obtained from the droplet adhesion amount calculation unit 203 and the sheet information obtained from the sheet information input unit 205, the main control unit 201 judges how easily the ink will dry, and the drying control unit 209 controls the drying strength of the drying means 23 in accordance with the judged ease of drying, thereby achieving good drying processing.

[0026] <Drying device configuration> Next, the configuration of the drying device 10 according to the first embodiment of the present invention will be described in detail with reference to FIGS.

[0027] As shown in FIG. 3, the drying device 10 according to the first embodiment of the present invention includes, in addition to the drying means 23 and the conveying belt 18, an upstream support roller 24, a downstream support roller 25, a belt drive motor 26, and an adsorption means 30.

[0028] The conveyor belt 18 is an endless belt, and is supported by being stretched across an upstream support roller 24 and a downstream support roller 25. The upstream support roller 24 is disposed upstream of the drying means 23 in the sheet conveying direction A, and is a driven roller that supports the conveyor belt 18 from the inside. On the other hand, the downstream support roller 25 is disposed downstream of the drying means 23 in the sheet conveying direction A, and is a drive roller that supports the conveyor belt 18 from the inside. When the downstream support roller 25 is driven to rotate by the drive of the belt drive motor 26, the conveyor belt 18 rotates, and the sheet S on the conveyor belt 18 is conveyed in the sheet conveying direction A.

[0029] The suction means 30 is a means for adsorbing the sheet S to the conveyor belt 18. As shown in FIG. 4, the suction means 30 has a suction member 31 and a negative pressure generating means 32. The suction member 31 is a member disposed inside the conveyor belt 18 and for sucking air through a plurality of suction holes 18a provided in the conveyor belt 18. The negative pressure generating means 32 is a means for generating a negative pressure for sucking air into the suction member 31. The negative pressure generating means 32 is connected to the suction member 31 via an air passage such as a duct, and is disposed outside the conveyor belt 18. A fan or a blower is used as the negative pressure generating means 32. When the negative pressure generating means 32 generates a negative pressure in the suction member 31, air is sucked through the suction holes 18a on the upper surface of the conveyor belt 18, and the sheet S is adsorbed to the upper surface of the conveyor belt 18 by the sucked air.

[0030] The drying means 23 face the sheet adsorption surface 18b, which is the upper surface of the conveyor belt 18, and are arranged in a line in the sheet conveying direction A. When the sheet S is conveyed while being adsorbed to the sheet adsorption surface 18b, the sheet S passes through the drying means 23 in order from the upstream side in the sheet conveying direction A, and is dried by each drying means 23.

[0031] In the first embodiment of the present invention, a plurality of suction members 31 are also provided corresponding to the drying means 23. That is, a plurality of suction members 31 are arranged side by side in the sheet conveying direction A so as to face each drying means 23 via the conveying belt 18. A plurality of negative pressure generating means 32 are also provided corresponding to the suction members 31.

[0032] <Problems with drying equipment> Here, problems with the drying device will be described using the configuration according to the first embodiment of the present invention as an example.

[0033] 3, when the sheet S is conveyed while being attracted to the conveyor belt 18, the drying process is sequentially performed by a plurality of drying means 23, thereby accelerating the drying of the ink on the sheet S. At this time, as the sheet S is conveyed downstream, the sheet S is heated by the drying process, and may deform. If the sheet S deforms, a gap is generated between the sheet S and the conveyor belt 18, and there is a risk that the sheet cannot be attracted well.

[0034] In addition, in a configuration in which the suction member 31 is disposed inside the conveyor belt 18, it is difficult to dispose the suction member 31 close to the upstream support roller 24 and the downstream support roller 25, so there is a problem that the suction force of the suction member 31 is difficult to obtain near the upstream support roller 24 and the downstream support roller 25. In general, at least one of the upstream support roller 24 and the downstream support roller 25 is configured to be movable in a direction toward and away from the other roller in order to eliminate the variation in tension of the conveyor belt 18 due to the dimensional tolerance of the conveyor belt 18. For this reason, the suction member 31 must be disposed with a space (interval) from the upstream support roller 24 or the downstream support roller 25 so as to avoid interference with the moving upstream support roller 24 or the downstream support roller 25. Therefore, it is not possible to dispose the suction member 31 close to the upstream support roller 24 or the downstream support roller 25, so there is a problem that good suction is difficult to obtain near the upstream support roller 24 and the downstream support roller 25.

[0035] 15, in a configuration in which the drying device 10 includes an air blowing means 40 that blows air to the sheet S to promote drying of the sheet S, when air is blown from the air blowing means 40 toward the conveyor belt 18 in a direction perpendicular to the sheet adsorption surface 18b, there is a problem that the leading edge e of the sheet S may be lifted or turned up from the conveyor belt 18 by the air flowing upstream in the sheet conveying direction A. The lifting and turning up of the leading edge of the sheet leads to poor conveyance of the sheet S, so in order to achieve good conveyance of the sheet S, it is necessary to suppress the lifting and turning up of the leading edge of the sheet.

[0036] Thus, in a drying device that conveys a sheet while adsorbing it, there are problems such as poor adsorption due to deformation of the sheet, poor adsorption due to insufficient suction force near the support roller, and poor adsorption due to the leading edge of the sheet lifting up or rolling up due to blowing air. Furthermore, such problems of poor adsorption tend to be more pronounced with small-sized sheets. That is, small-sized sheets have a smaller area that blocks the suction holes 18a of the conveyor belt 18 than large-sized sheets, so it is difficult to obtain negative pressure, and the problem of poor adsorption tends to occur more easily.

[0037] Therefore, in the first embodiment of the present invention, the following measures are taken to improve the sheet adsorption failure: The configuration of the characteristic portion according to the first embodiment of the present invention will be described below.

[0038] <Characteristic part configuration> FIG. 5 is a diagram showing the configuration of a characteristic portion of the drying device 10 according to the first embodiment of the present invention.

[0039] In FIG. 5, arrows B1 to B3 indicate the suction forces generated by the suction members 31. The length of each of the arrows B1 to B3 indicates the magnitude of the suction force. As shown in FIG. 5, the drying device 10 according to the first embodiment of the present invention is configured so that the suction force of the suction members 31 on the downstream side in the sheet conveying direction A is greater (B1 <B2<B3)。

[0040] In this way, by making the suction force of the suction member 31 stronger toward the downstream side in the sheet conveying direction A, the sheet S can be well attracted even if the sheet S is deformed by heat during the drying process. That is, the sheet S is attracted with a stronger suction force on the downstream side in the sheet conveying direction A where the sheet S is likely to deform than on the upstream side, so that the occurrence of a gap between the sheet S and the conveying belt 18 due to deformation of the sheet S can be suppressed. This makes it possible to well attract the sheet S to the conveying belt 18.

[0041] Further, the suction forces B1 to B3 of each suction member 31 are not limited to the case where they increase in order toward the downstream side in the sheet conveyance direction A (B1 < B2 < B3), and only the suction force B3 of the suction member 31 arranged on the most downstream side in the sheet conveyance direction A may be made larger than the suction forces B1 and B2 of the other upstream suction members 31 (B1 = B2 < B3). That is, among the plurality of suction members 31, the suction force of some or one suction member 31 may be made different from the suction forces of the other suction members 31. Note that the degree to which the suction force of the downstream suction member 31 is increased may be appropriately determined in consideration of the degree of deformation of the sheet S, etc. Also, the number of suction members 31 is not limited to three, and may be two, or four or more.

[0042] The magnitude of the suction force of each suction member 31 can be made different by individually setting the magnitude of the negative pressure generated by each negative pressure generating means 32. Also, the magnitude of the suction force of the suction member 31 may be adjustable according to the material or rigidity of the conveyed sheet S, etc. For example, when a sheet S that is not easily deformed is conveyed, since it may not be necessary to increase the suction force on the downstream side in the sheet conveyance direction A, the suction forces of each suction member 31 may be set to the same magnitude. On the other hand, when a sheet S that is easily deformed is conveyed, it is preferable to increase the suction force on the downstream side in the sheet conveyance direction A.

[0043] <Configuration of Other Embodiments> Subsequently, other embodiments different from the first embodiment of the present invention will be described. Hereinafter, the parts different from the first embodiment of the present invention will be mainly described, and the description of the same parts will be omitted as appropriate.

[0044] <Second Embodiment of the Present Invention> FIG. 6 is a diagram showing the configuration of the characteristic part of the drying apparatus 10 according to the second embodiment of the present invention.

[0045] 6, in the second embodiment of the present invention, the suction means 30 has, in addition to the first suction member 31, a second suction member 33 separate from the first suction member 31. The first suction member 31 here is a suction member disposed inside the conveyor belt 18 so as to face the drying means 23 with the conveyor belt 18 therebetween, like the suction member 31 according to the first embodiment of the present invention. On the other hand, the second suction member 33 is a suction member separate from the first suction member 31, and is disposed between the first suction member 31 at the most upstream position in the sheet conveying direction A and the upstream support roller 24, and between the first suction member 31 at the most downstream position in the sheet conveying direction A and the downstream support roller 25.

[0046] In this manner, the second suction member 33, which is separate from the first suction member 31, is disposed between the most upstream first suction member 31 and the upstream support roller 24, and between the most downstream first suction member 31 and the downstream support roller 25, thereby making it possible to ensure suction force in the vicinity of the upstream support roller 24 and the downstream support roller 25. This makes it possible to satisfactorily attract the sheet S in the vicinity of the upstream support roller 24 and the downstream support roller 25.

[0047] Since the second suction member 33 is disposed in a limited space between the upstream and downstream support rollers 24, 25 and the first suction member 31, it is preferable that the second suction member 33 is smaller than the first suction member 31. Therefore, it is preferable that the length of the second suction member 33 in the sheet conveying direction A is shorter than the length of the first suction member 31 in the sheet conveying direction A. In addition, if the direction perpendicular to the sheet adsorption surface 18b of the conveyor belt 18 is defined as the "width direction" of the first suction member 31 and the second suction member 33, it is preferable that the width of the second suction member 33 is equal to or smaller than the width of the first suction member 31.

[0048] As shown in FIG. 7, in the second embodiment of the present invention, the second suction member 33 is configured to be movable together with the downstream support roller 25. This allows the second suction member 33 to be disposed in the vicinity of the downstream support roller 25. That is, even if the downstream support roller 25 moves in the direction of the arrow in FIG. 7 to adjust the tension of the conveyor belt 18, the second suction member 33 moves following the movement of the downstream support roller 25 at this time, so that it is not necessary to secure a space between the second suction member 33 and the downstream support roller 25 to avoid interference between them. As a result, the second suction member 33 can be disposed in the vicinity of the downstream support roller 25, so that the suction force in the vicinity of the downstream support roller 25 can be secured. In addition, when the upstream support roller 24 functions as a tension adjustment roller, instead of the downstream support roller 25, the second suction member 33 can be configured to be movable following the movement of the upstream support roller 24, so that the second suction member 33 can be disposed in the vicinity of the upstream support roller 24. The second suction member 33 is not limited to being disposed near both the upstream support roller 24 and the downstream support roller 25, and may be disposed near only one of them.

[0049] 8, in the second embodiment of the present invention, the second suction member 33 has a sharp suction portion 33a having a wedge-shaped cross section tapered toward the upstream support roller 24 and the downstream support roller 25. The sharp suction portion 33a is disposed on the sheet adsorption surface 18b of the conveyor belt 18 so as to enter the wedge-shaped gap C between the support rollers 24, 25 and the conveyor belt 18, so that the second suction member 33 can be disposed closer to the support rollers 24, 25. Air is also sucked in by the sharp suction portion 33a, so that suction can be performed at a position closer to the support rollers 24, 25, and therefore the suction force in the vicinity of the support rollers 24, 25 can be more effectively exerted.

[0050] 9, in the second embodiment of the present invention, the upstream second suction member 33 is disposed upstream of the most upstream drying means 23 in the sheet conveying direction A and downstream of the upstream support roller 24 in the sheet conveying direction A. The downstream second suction member 33 is disposed downstream of the most downstream drying means 23 in the sheet conveying direction A and upstream of the downstream support roller 25 in the sheet conveying direction A. In other words, the upstream and downstream second suction members 33 are not disposed in positions facing the drying means 23 across the conveying belt 18. Therefore, each second suction member 33 is in an environment where it is less susceptible to the heat from the drying means 23.

[0051] In contrast, the first suction member 31 is disposed at a position facing the drying means 23 across the conveyor belt 18, and is therefore susceptible to the heat from the drying means 23. For this reason, the negative pressure generating means 32 is disposed outside the conveyor belt 18 (see FIG. 4). In other words, if the negative pressure generating means 32 is disposed inside the first suction member 31, there is a risk that the negative pressure generating means 32 will be affected by the heat from the drying means 23, causing parts to deteriorate or performance to decrease. Therefore, the negative pressure generating means 32 is disposed outside the conveyor belt 18, rather than inside the first suction member 31.

[0052] On the other hand, since the second suction member 33 is not easily affected by the heat from the drying means 23, as shown in Fig. 9, the negative pressure generating means 34 is disposed inside the second suction member 33. This makes it possible to save space and reduce the size.

[0053] In addition, since the first suction member 31 and the second suction member 33 are provided with separate negative pressure generating means 32, 34, it is possible to individually set the suction force of each of the first suction member 31 and the second suction member 33. For example, the suction force of the second suction member 33 on the downstream side may be set to be greater than the suction forces of the first suction member 31 and the second suction member 33 on the upstream side, so that the suction force on the downstream side in the sheet conveying direction A can be satisfactorily secured.

[0054] Third embodiment of the present invention FIG. 10 is a diagram showing the configuration of a characteristic portion of a drying device 10 according to a third embodiment of the present invention.

[0055] 10, the drying device 10 according to the third embodiment of the present invention includes an air blowing means 40 that blows air to the sheet S. A fan, a blower, or the like is used as the air blowing means 40. The air blowing means 40 blows air to the sheet S adsorbed to the conveyor belt 18, thereby accelerating the drying of the sheet S.

[0056] Here, the air blowing means 40 has an air blowing port 41 arranged to face the downstream side of the sheet conveying direction A. That is, in the third embodiment of the present invention, unlike the example shown in Fig. 15, the air blowing port 41 is arranged to face not in a direction perpendicular to the sheet adsorption surface 18b of the conveying belt 18 but in a direction inclined toward the downstream side from a direction perpendicular to the sheet adsorption surface 18b.

[0057] In this way, by arranging the air outlet 41 so as to face the downstream side in the sheet transport direction A, air is blown from the air outlet 41 toward the downstream side in the sheet transport direction A. This makes it possible to reduce the amount of air flowing toward the upstream side in the sheet transport direction A, making it possible to suppress lifting or rolling up of the leading edge of the sheet S caused by air being blown against the leading edge of the sheet S. In this case, air is blown against the trailing edge of the sheet S, but even if the trailing edge of the sheet S lifts up or rolls up and gets caught on the drying means 23 or the like, the catch is released as the sheet S is transported, so transport failure is unlikely to occur.

[0058] 11, the "direction in which the air outlet 41 faces" does not mean the direction of the opening 41a shown in Fig. 11, but means the direction in which the ventilation passage 41b near the opening 41a extends. Therefore, although the direction of the opening 41a itself is different between Fig. 11(a) and (b), the directions in which the ventilation passage 41b near the opening 41a extends are both directions facing the downstream side of the sheet conveying direction A, so the "direction in which the air outlet 41 faces" is also the downstream side of the sheet conveying direction A.

[0059] The number of the air blowing means 40 may be multiple or may be one. When multiple air blowing means 40 are provided, the air volumes of the air blowing means 40 may be different from each other or may be the same. Also, the air volume of the air blowing means 40 may be adjustable according to the rigidity of the sheet S being transported. For example, when thin paper with low rigidity is transported, the air volume of the air blowing means 40 may be reduced compared to when thick paper with high rigidity is transported, thereby more reliably suppressing the sheet S from floating up or turning over due to the air blowing.

[0060] Furthermore, since the stiffness of the sheet S is correlated with the "basis weight", which is the mass per unit area of ​​the sheet, the air volume may be changed according to the basis weight.

[0061] In this case, as shown in Fig. 12, the control unit 200 includes an air volume control unit 210 that controls the air volume of the blowing means 40 based on the basis weight of the sheet obtained from the sheet information input unit 205. The air volume control unit 210 sets the maximum current value supplied to the blowing means 40 or the maximum rotation speed of the fan as the maximum output (100%), and controls the air volume by changing the ratio of the output to the maximum output (duty ratio). The maximum air volume output is, for example, 3.0 [m 3 / mim] or more 4.0[m 3 / mim] will be set to the range below.

[0062] FIG. 13 shows an example of a control flow for controlling the air volume.

[0063] As shown in FIG. 13, when the printing operation is started, first, it is determined whether the basis weight of the sheet is less than 170 [gsm]. This determination is made by the main control unit 201 which acquires information on the basis weight of the sheet from the sheet information input unit 205. Then, when it is determined that the basis weight is less than 170 [gsm], the air volume is set within a range of 10% to less than 30% of the maximum output. On the other hand, when it is determined that the basis weight is 170 [gsm] or more, the air volume is set within a range of 30% to 50% of the maximum output. The setting of the air volume in each case is made by the air volume control unit 210 which receives a control signal from the main control unit 201. Then, when the sheet is conveyed to a position facing the blowing means 40, air is blown from the blowing means 40 to the sheet S at the set air volume.

[0064] In this way, when the basis weight is less than 170 [gsm], the air volume is relatively reduced to prevent the sheet S, which has low rigidity, from lifting or curling up. On the other hand, when the basis weight is 170 [gsm] or more, the air volume is relatively increased to promote drying of the sheet S.

[0065] The basis weight value that is the criterion for controlling the air volume is not limited to 170 [gsm], but can be set arbitrarily depending on the type of sheet, etc. Similarly, the air volume to be set can also be set arbitrarily.

[0066] As described above, according to each embodiment of the present invention, the sheet can be satisfactorily attracted and conveyed, so that it is possible to improve the sheet attraction failure. Furthermore, the configurations according to each embodiment may be implemented independently, or two or more of them may be combined.

[0067] Here, the "liquid ejection device" according to the present invention includes various liquid ejection devices, as long as the device includes an inkjet type image forming device, which is an example of a liquid ejection device, and is equipped with a liquid ejection unit and ejects liquid onto a sheet by driving the liquid ejection unit. Therefore, the "liquid ejection device" according to the present invention is not limited to a device that visualizes meaningful images such as characters and figures using ejected liquid. For example, the "liquid ejection device" also includes a device that forms a pattern that has no meaning in itself, a device that creates a three-dimensional image, and even a treatment liquid ejection device that ejects a treatment liquid onto the surface of a sheet for the purpose of modifying the surface of the sheet.

[0068] Furthermore, the "liquid ejection device" according to the present invention may include means for feeding, conveying, and discharging a sheet, a pre-processing device, and a post-processing device. Furthermore, the "liquid ejection device" may be one in which the liquid ejection section moves relatively to the sheet, or one in which the liquid ejection section does not move relatively. Specific examples include a serial type liquid ejection device in which the liquid ejection head (liquid ejection section) moves, and a line type liquid ejection device in which the liquid ejection head (liquid ejection section) does not move.

[0069] The "sheet" onto which the liquid is ejected includes any material to which the liquid can adhere at least temporarily, and includes materials to which the liquid can adhere and stick, and materials to which the liquid can adhere and penetrate. Specific examples include recording media such as paper, recording paper, film, and cloth, and electronic boards. The material of the "sheet" may be any material to which the liquid can adhere even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, and ceramics.

[0070] The "liquid" discharged by the "liquid discharge device" may have a viscosity or surface tension that allows it to be discharged from the liquid discharge unit, and is not particularly limited. However, it is preferable that the viscosity of the liquid is 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or a pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, an amino acid, a protein, or calcium, an edible material such as a natural dye, etc. These can be used for applications such as inkjet ink, a surface treatment liquid, a component of an electronic element or a light-emitting element, a liquid for forming an electronic circuit resist pattern, and a material liquid for three-dimensional modeling.

[0071] As the drying means provided in the drying device according to the present invention, for example, ultraviolet ray irradiation means such as those listed below can be used.

[0072] <Configuration of ultraviolet irradiation means> FIG. 14 is a perspective view of an ultraviolet ray irradiation means 17 which is an example of the drying means.

[0073] As the light source of the ultraviolet irradiation means 17, an LED is preferable, and among them, a light emitting diode (UV-LED) that emits ultraviolet light is preferable. The ultraviolet irradiation means 17 shown in FIG. 14 has an irradiation surface 17a on which a plurality of granular UV-LED light emitting elements 170 are arranged. Each UV-LED light emitting element 170 emits light with the same illuminance, so that the irradiation surface 17a as a whole emits light uniformly. When an LED is used as the light source, unlike a metal halide lamp, the wavelength as a light source tends to be sharp with a single peak even without using a wavelength cut filter. This makes it possible to reduce the difference in the progress of drying due to the color difference of the ink.

[0074] The ultraviolet light (UV light) irradiated from the ultraviolet light irradiation means 17 is preferably ultraviolet light having a peak wavelength of 300 nm or more and 400 nm or less. The wavelength distribution of the ultraviolet light is not particularly limited and can be changed as appropriate. For example, the full width at half maximum can be about 15 nm.

[0075] <Ink> Next, the ink used in the present invention will be described, although the ink is not limited to the ink below.

[0076] The ink includes a liquid composition mainly composed of water or an organic solvent, or both of them. An ink including such a liquid composition can also be called an aqueous ink. The liquid composition may include an ultraviolet polymerization initiator and an ultraviolet polymerizable compound, but if the liquid composition includes these, the content of the ultraviolet polymerization initiator and the ultraviolet polymerizable compound is suppressed to less than a predetermined amount. Therefore, even if ultraviolet rays are irradiated from the ultraviolet irradiation means 17 to ink containing less than a predetermined amount of the ultraviolet polymerization initiator and the ultraviolet polymerizable compound, curing by polymerization reaction does not occur or hardly occurs.

[0077] On the other hand, in the case of a UV-curable material such as a UV ink containing a predetermined amount or more of an ultraviolet polymerization initiator and an ultraviolet polymerizable compound, when ultraviolet light is irradiated, the initiator in a radical or cationic active state reacts with the ultraviolet polymerizable compound, causing the ultraviolet polymerizable compound to polymerize and harden into a resin. This fixes the ink to the sheet. However, when a UV-curable material is used, there is a problem that a small amount of radical or cationic active substance may remain in the printed image after hardening, making it difficult to obtain a safe printed matter. In addition, the initiator and polymerizable compound are expensive, which also causes a problem of high running costs.

[0078] Therefore, by using an ink having a low content of ultraviolet polymerization initiator and ultraviolet polymerizable compound, it is possible to reduce running costs and obtain printed matter having good safety.

[0079] <Liquid composition> Next, the liquid composition contained in the ink will be described, although the liquid composition is not limited to the following liquid composition.

[0080] The liquid composition contains water or an organic solvent, and if necessary, contains other components such as a coloring material, a resin, etc. The liquid composition may also contain an ultraviolet polymerization initiator and an ultraviolet polymerizable compound.

[0081] The liquid composition can be used, for example, as a colored ink, a pretreatment liquid (undercoat liquid), a posttreatment liquid (protector coat liquid), or the like.

[0082] -UV polymerization initiators and UV polymerizable compounds- The liquid composition may contain an ultraviolet polymerization initiator and an ultraviolet polymerizable compound, but when the liquid composition contains these, the content of the ultraviolet polymerization initiator and the ultraviolet polymerizable compound is controlled to less than a predetermined amount, so that even if the liquid composition is irradiated with ultraviolet rays from an ultraviolet irradiation means, curing due to a polymerization reaction does not occur or hardly occurs.

[0083] When the liquid composition contains an ultraviolet polymerization initiator and an ultraviolet polymerizable compound, the content of the ultraviolet polymerization initiator is less than 0.1 mass % in the liquid composition, or the content of the ultraviolet polymerizable compound is less than 5 mass % in the liquid composition. When the liquid composition contains 0.1 mass % or more of the ultraviolet polymerization initiator and 5 mass % or more of the ultraviolet polymerizable compound, the cost increases and it becomes difficult to obtain a printed matter having good safety.

[0084] Examples of ultraviolet polymerization initiators include those capable of generating active species such as radicals or cations by UV (ultraviolet rays) and initiating polymerization of polymerizable compounds (monomers, oligomers). As such polymerization initiators, known radical polymerization initiators, cationic polymerization initiators, base generators, etc. are used alone or in combination of two or more.

[0085] Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

[0086] The ultraviolet-polymerizable compound is not particularly limited and can be appropriately changed. For example, a known polymerizable compound can be used. The polymerizable compound may be a monomer or an oligomer. For example, methacrylic acid can be used.

[0087] -water- The water content in the liquid composition is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of drying property and ejection reliability, however, it is preferably from 10% by mass to 90% by mass, and more preferably from 20% by mass to 60% by mass.

[0088] -Organic solvents- The organic solvent is not particularly limited, and any water-soluble organic solvent can be used. Examples of the organic solvent include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers, and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.

[0089] Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, and 1,4-pentanediol. Examples of suitable hexanediols include 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol.

[0090] Examples of polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether.

[0091] Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0092] Examples of the nitrogen-containing heterocyclic compounds include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone.

[0093] Examples of the amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide.

[0094] Examples of the amines include monoethanolamine, diethanolamine, and triethylamine.

[0095] Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol.

[0096] Other organic solvents include propylene carbonate, ethylene carbonate, and the like.

[0097] It is preferable to use an organic solvent having a boiling point of 250° C. or less, since this not only functions as a wetting agent but also provides good drying properties.

[0098] As the organic solvent, polyol compounds having 8 or more carbon atoms and glycol ether compounds are also suitably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.

[0099] Specific examples of glycol ether compounds include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0100] Polyol compounds having 8 or more carbon atoms and glycol ether compounds can improve the permeability of ink when paper is used as the sheet.

[0101] The content of the organic solvent in the liquid composition is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of drying property and ejection reliability, however, the content is preferably from 10% by mass to 60% by mass, and more preferably from 20% by mass to 60% by mass.

[0102] -Water and organic solvent content- The total amount of water and organic solvent in the liquid composition is preferably 80% by mass or more, and more preferably 90% by mass or more, in which case ejection properties can be improved.

[0103] -Coloring materials- The coloring material is not particularly limited, and pigments and dyes can be used.

[0104] As the pigment, an inorganic pigment or an organic pigment can be used. These can be used alone or in combination of two or more. Also, mixed crystals can be used as the pigment.

[0105] Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments.

[0106] As inorganic pigments, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used.

[0107] As organic pigments, azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be used. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.

[0108] Specific examples of pigments for black colors include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (CI Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (CI Pigment Black 1).

[0109] In addition, for color, CI Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, CI Pigment Orange Range 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 (Red oxide), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, CI Pi CI Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38; CI Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.

[0110] The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. One type of dye may be used alone, or two or more types may be used in combination.

[0111] Dyes such as CI Acid Yellow 17, 23, 42, 44, 79, 142, CI Acid Red 52, 80, 82, 249, 254, 289, CI Acid Blue 9, 45, 249, CI Acid Black 1, 2, 24, 94, CI Food Black 1, 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Directed Black 19, 38, 51, 71, 154, 168, 171, 195, CI Reactive Red 14, 32, 55, 79, 249, and CI Reactive Black 3, 4, and 35.

[0112] The content of the coloring material in the liquid composition is preferably from 0.1% to 15% by mass, and more preferably from 1% to 10% by mass, from the viewpoints of improving image density, good fixing property and ejection stability.

[0113] Methods for dispersing a pigment to obtain a liquid composition include a method of introducing a hydrophilic functional group into a pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant.

[0114] An example of a method for making a pigment self-dispersible by introducing a hydrophilic functional group into the pigment is a method in which a functional group such as a sulfone group or a carboxyl group is added to the pigment (e.g., carbon) to make it dispersible in water.

[0115] As a method for dispersing a pigment by coating its surface with a resin, a method for encapsulating the pigment in a microcapsule to make it dispersible in water can be mentioned. This can be called a resin-coated pigment. In this case, it is not necessary for all the pigments to be blended in the liquid composition to be coated with a resin, and uncoated or partially coated pigments may be dispersed in the liquid composition within a range that does not impair the effects of the present invention.

[0116] Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a known polymeric dispersant, such as a surfactant.

[0117] As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the pigment. As the dispersant, in addition to RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd., sodium naphthalenesulfonate formalin condensate can also be suitably used. The dispersant may be used alone or in combination of two or more kinds.

[0118] A liquid composition such as ink can be obtained by mixing a pigment with materials such as water or an organic solvent. A liquid composition can also be produced by mixing a pigment with other materials such as water and a dispersant to prepare a pigment dispersion and then mixing the pigment with materials such as water or an organic solvent.

[0119] The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. Dispersion is preferably performed using a dispersing machine.

[0120] The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency in terms of the maximum number is preferably 20 nm or more and 500 nm or less, more preferably 20 nm or more and 150 nm or less, in order to improve the dispersion stability of the pigment and the image quality such as ejection stability and image density. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0121] The pigment content in the pigment dispersion is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of obtaining good ejection stability and increasing image density, it is preferably 0.1% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass. It is preferable to filter coarse particles from the pigment dispersion using a filter, a centrifugal separator, or the like, and degas the pigment dispersion as necessary.

[0122] -resin- The type of resin contained in the liquid composition is not particularly limited and can be appropriately selected depending on the purpose. Examples of the resin include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic styrene resin, and acrylic silicone resin.

[0123] Resin particles made of these resins may be used. The resin particles may be dispersed in water as a dispersion medium to form a resin emulsion, and then mixed with materials such as a coloring material and an organic solvent to obtain a liquid composition. The resin particles may be appropriately synthesized or may be commercially available. These may be used alone or in combination of two or more types of resin particles.

[0124] The volume average particle diameter of the resin particles is not particularly limited and can be appropriately selected according to the purpose, but from the viewpoint of obtaining good fixing property and high image hardness, it is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less. The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

[0125] The resin content is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of fixation property and storage stability of the liquid composition, however, the resin content is preferably from 1 mass % to 30 mass % and more preferably from 5 mass % to 20 mass % of the total amount of the liquid composition.

[0126] -Other ingredients- If necessary, surfactants, antifoaming agents, antiseptic and antifungal agents, rust inhibitors, pH adjusters, etc. may be added to the liquid composition.

[0127] -Pretreatment liquid (undercoat liquid)- When the liquid composition is used as a pretreatment liquid, the pretreatment liquid contains an organic solvent and water, and may contain a flocculant, a surfactant, an antifoaming agent, a pH adjuster, an antiseptic and antifungal agent, an antirust agent, etc. as necessary. The organic solvent, the surfactant, the antifoaming agent, the pH adjuster, the antiseptic and antifungal agent, and the antirust agent may be the same materials as those used in the liquid composition, and other materials used in known treatment liquids may be used. The type of the flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, and polyvalent metal salts.

[0128] -Post-treatment liquid (protector coating liquid)- When the liquid composition is used as the post-treatment liquid, the post-treatment liquid is not particularly limited as long as it can form a transparent layer. The post-treatment liquid is obtained by selecting and mixing organic solvents, water, resins, surfactants, defoamers, pH adjusters, antiseptics, antifungals, rust inhibitors, etc. as necessary. The post-treatment liquid may be applied to the entire image area formed on the sheet, or may be applied only to a selected area.

[0129] <Curable composition> In the present invention, in addition to the liquid composition, a curable composition that is cured by ultraviolet light may be applied to the sheet. When such a curable composition is used, the liquid composition is dried and cured at the same time by the ultraviolet light irradiation means, which is advantageous in that there is no need to provide a separate curing means.

[0130] The curable composition can be used as a colored ink, a white ink, a clear ink, a pretreatment liquid (undercoat liquid), a posttreatment liquid (protector coat liquid), etc. Among them, it is preferable to use it as a white ink or a clear ink. When it is a UV curable ink, it can be called a UV ink, etc.

[0131] When a curable composition is used, the safety and cost are inferior to those when a curable composition is not used, but by adding a special color such as white or clear, a printed matter with added value can be obtained. Furthermore, in the present invention, even when a curable composition is used, a liquid composition can be used in combination, so that a printed matter with good safety can be obtained with reduced running costs compared to the conventional example in which, for example, the black ink, cyan ink, magenta ink, yellow ink, and white ink are all UV-curable inks.

[0132] When using a curable composition, the order of application to the sheet may be changed as appropriate, as long as it is before the sheet is irradiated with ultraviolet light. It may be before the liquid composition is applied to the sheet, after the liquid composition is applied to the sheet, or simultaneously. In addition, the region to which the curable composition is applied may be changed as appropriate, and may be the same place as the liquid composition.

[0133] The curable composition contains, for example, a polymerization initiator and a polymerizable compound, and may contain other components such as a coloring material and an organic solvent, if necessary.

[0134] -Polymerization initiators and polymerizable compounds- As the polymerization initiator and the polymerizable compound, an ultraviolet polymerization initiator and an ultraviolet polymerizable compound can be used.

[0135] The polymerization initiator may be any one that can generate active species such as radicals or cations by ultraviolet light irradiated by an ultraviolet irradiation means and initiate polymerization of a polymerizable compound (monomer or oligomer). As such a polymerization initiator, known radical polymerization initiators, cationic polymerization initiators, base generators, etc., can be used alone or in combination of two or more, and among them, it is preferable to use a radical polymerization initiator. In addition, in order to obtain a sufficient curing speed, the polymerization initiator is preferably contained in an amount of 5 to 20% by mass relative to the total mass (100% by mass) of the curable composition.

[0136] Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

[0137] In addition to the polymerization initiator, a polymerization accelerator (sensitizer) can also be used in combination. The polymerization accelerator is not particularly limited, but for example, amine compounds such as trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, 2-ethylhexyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, and 4,4'-bis(diethylamino)benzophenone are preferred, and the content thereof may be appropriately set depending on the polymerization initiator used or its amount.

[0138] -Coloring materials- As the coloring material, various pigments or dyes that impart black, white, magenta, cyan, yellow, green, orange, gold, silver, etc. can be used, and coloring materials used in liquid compositions can be used.

[0139] The content of the coloring material may be appropriately determined in consideration of the desired color density and dispersibility in the composition, and is not particularly limited, but is preferably 0.1 to 20 mass% relative to the total mass (100 mass%) of the curable composition. The curable composition may be colorless and transparent without containing a coloring material, and in that case, it is suitable as, for example, an overcoat layer (protector coat layer) for protecting an image.

[0140] - Organic solvents - As the organic solvent, an organic solvent used in a liquid composition can be used. The curable composition may contain an organic solvent, but it is preferable that the composition does not contain an organic solvent if possible. If the composition does not contain an organic solvent, particularly a volatile organic solvent (VOC (Volatile Organic Compounds)-free composition), the safety of the place where the composition is handled is improved and it is possible to prevent environmental pollution. Note that the "organic solvent" means a general non-reactive organic solvent such as ether, ketone, xylene, ethyl acetate, cyclohexanone, toluene, etc., and should be distinguished from a reactive monomer. In addition, "not containing" an organic solvent means that the organic solvent is substantially not contained, and it is preferable that the organic solvent is less than 0.1 mass%.

[0141] The other components are not particularly limited, and examples thereof include conventionally known surfactants, polymerization inhibitors, leveling agents, defoamers, fluorescent brightening agents, penetration promoters, wetting agents (moisturizing agents), fixing agents, viscosity stabilizers, antifungal agents, preservatives, antioxidants, ultraviolet absorbers, chelating agents, pH adjusters, and thickeners.

[0142] -Preparation- The curable composition can be prepared using the various components described above. The preparation means and conditions are not particularly limited. For example, the curable composition can be prepared by putting a polymerizable monomer, a pigment, a dispersant, etc. into a dispersing machine such as a ball mill, a Kitty mill, a disk mill, a pin mill, or a Dyno mill, dispersing the ingredients to prepare a pigment dispersion, and then mixing a polymerizable monomer, an initiator, a polymerization inhibitor, a surfactant, etc. into the pigment dispersion.

[0143] -viscosity- The viscosity of the curable composition may be adjusted appropriately depending on the application or application means, and is not particularly limited. For example, when applying an ejection means that ejects the composition from a nozzle, the viscosity in the range of 20°C to 65°C, desirably the viscosity at 25°C is preferably 3 to 40 mPa·s, more preferably 5 to 15 mPa·s, and particularly preferably 6 to 12 mPa·s. It is particularly preferable that the viscosity range is satisfied without containing an organic solvent. The viscosity can be measured by using a cone-plate type rotational viscometer VISCOMETER TVE-22L manufactured by Toki Sangyo Co., Ltd., using a cone rotor (1°34'×R24), with a rotation speed of 50 rpm and a temperature of the constant temperature circulating water appropriately set in the range of 20°C to 65°C. A VISCOMATE VM-150III can be used to adjust the temperature of the circulating water.

[0144] To summarize the above-described aspects of the present invention, the present invention includes at least the following aspects.

[0145] [First aspect] The first aspect is a drying device comprising an endless conveying belt for conveying a sheet, an adsorption means for adsorbing the sheet to the conveying belt, and a drying means arranged opposite the sheet adsorption surface of the conveying belt for drying the sheet, wherein the adsorption means comprises a plurality of suction members arranged in a line in the sheet conveying direction inside the conveying belt, and the suction force of at least one of the plurality of suction members is different from the suction force of the other suction members.

[0146] [Second aspect] A second aspect is the drying device of the first aspect, wherein the suction force of a suction member on a downstream side in a sheet transport direction among the plurality of suction members is greater than the suction force of a suction member on an upstream side in the sheet transport direction.

[0147] [Third aspect] A third aspect is a drying device comprising an endless conveying belt for conveying a sheet, an adsorption means for adsorbing the sheet to the conveying belt, a drying means arranged opposite the sheet adsorption surface of the conveying belt for drying the sheet, an upstream support roller arranged upstream of the drying means in the sheet conveying direction and supporting the conveying belt from the inside, and a downstream support roller arranged downstream of the drying means in the sheet conveying direction and supporting the conveying belt from the inside, wherein the adsorption means has a first suction member arranged inside the conveying belt so as to face the drying means across the conveying belt, and a second suction member arranged inside the conveying belt downstream of the drying means in the sheet conveying direction and upstream of the downstream support roller in the sheet conveying direction.

[0148] [Fourth aspect] A fourth aspect is a drying device comprising an endless conveying belt for conveying a sheet, an adsorption means for adsorbing the sheet to the conveying belt, a drying means arranged opposite the sheet adsorption surface of the conveying belt for drying the sheet, an upstream support roller arranged upstream of the drying means in the sheet conveying direction and supporting the conveying belt from the inside, and a downstream support roller arranged downstream of the drying means in the sheet conveying direction and supporting the conveying belt from the inside, wherein the adsorption means has a first suction member arranged inside the conveying belt so as to face the drying means across the conveying belt, and a second suction member arranged inside the conveying belt upstream of the drying means in the sheet conveying direction and downstream of the upstream support roller in the sheet conveying direction.

[0149] [Fifth aspect] A fifth aspect is the drying device according to the third aspect, wherein the second suction member is configured to be movable together with the downstream support roller.

[0150] [Sixth aspect] A sixth aspect is the drying device according to the fourth aspect, wherein the second suction member is configured to be movable together with the upstream support roller.

[0151] [Seventh aspect] A seventh aspect is the drying device according to any one of the third to sixth aspects, wherein a length of the second suction member in the sheet transport direction is shorter than a length of the first suction member in the sheet transport direction.

[0152] [Eighth aspect] An eighth aspect is any one of the third to seventh aspects, wherein the second suction member is a drying device having a negative pressure generating means therein.

[0153] [Ninth aspect] A ninth aspect is a drying device comprising an endless conveying belt for conveying a sheet, an adsorption means for adsorbing the sheet to the conveying belt, a drying means arranged opposite the sheet adsorption surface of the conveying belt for drying the sheet, and a blowing means for blowing air at the sheet adsorbed to the conveying belt, wherein the air outlet of the blowing means is arranged to face downstream in the sheet conveying direction.

[0154] [Tenth aspect] A tenth aspect is a liquid ejection device including a liquid ejection section that ejects liquid onto a sheet, and a drying device according to any one of the first to ninth aspects that dries the sheet onto which the liquid has been ejected. [Explanation of symbols]

[0155] 10 Drying equipment 13 Liquid discharge part 18 Conveyor belt 23 Drying means 24 Upstream support roller 25 Downstream support roller 30 Adsorption means 31 suction member (first suction member) 32 Negative pressure generating means 33 Second suction member 34 Negative pressure generating means 40 Air blowing means 41 Ventilation vent 100 Liquid dispensing device A Sheet transport direction S Seat [Prior art documents] [Patent documents]

[0156] [Patent Document 1] JP 2014-181130 A

Claims

1. an endless conveyor belt for conveying a sheet; an adsorption means for adsorbing the sheet to the conveyor belt; a drying means disposed opposite to the sheet adsorption surface of the conveyor belt and configured to dry the sheet, the suction unit includes a plurality of suction members arranged in a line in a sheet conveying direction on the inner side of the conveying belt, A drying device, characterized in that the suction force of at least one of the plurality of suction members is different from the suction forces of the other suction members.

2. 2. The drying device according to claim 1, wherein the suction force of the suction member on the downstream side in the sheet transport direction is greater than the suction force of the suction member on the upstream side in the sheet transport direction.

3. an endless conveyor belt for conveying a sheet; an adsorption means for adsorbing the sheet to the conveyor belt; a drying means arranged to face the sheet adsorption surface of the conveyor belt and configured to dry the sheet; an upstream support roller that is disposed upstream of the drying means in a sheet conveying direction and supports the conveying belt from an inside thereof; a downstream support roller that is disposed downstream of the drying means in a sheet conveying direction and supports the conveying belt from an inside thereof, The drying device is characterized in that the suction means includes a first suction member arranged on the inside of the conveying belt so as to face the drying means across the conveying belt, and a second suction member arranged on the inside of the conveying belt downstream of the drying means in the sheet conveying direction and upstream of the downstream support roller in the sheet conveying direction.

4. an endless conveyor belt for conveying a sheet; an adsorption means for adsorbing the sheet to the conveyor belt; a drying means arranged to face the sheet adsorption surface of the conveyor belt and configured to dry the sheet; an upstream support roller that is disposed upstream of the drying means in a sheet conveying direction and supports the conveying belt from an inside thereof; a downstream support roller that is disposed downstream of the drying means in a sheet conveying direction and supports the conveying belt from an inside thereof, The drying device is characterized in that the suction means includes a first suction member arranged on the inside of the conveying belt so as to face the drying means across the conveying belt, and a second suction member arranged on the inside of the conveying belt upstream of the drying means in the sheet conveying direction and downstream of the upstream support roller in the sheet conveying direction.

5. The drying device according to claim 3 , wherein the second suction member is configured to be movable together with the downstream support roller.

6. The drying device according to claim 4 , wherein the second suction member is configured to be movable together with the upstream support roller.

7. The drying device according to claim 3 or 4, wherein a length of the second suction member in the sheet transport direction is shorter than a length of the first suction member in the sheet transport direction.

8. 5. The drying apparatus according to claim 3, wherein the second suction member has a negative pressure generating means therein.

9. an endless conveyor belt for conveying a sheet; an adsorption means for adsorbing the sheet to the conveyor belt; a drying means arranged to face the sheet adsorption surface of the conveyor belt and configured to dry the sheet; A drying device including a blower that blows air to the sheet adsorbed on the conveyor belt, A drying device, characterized in that an air outlet of the air blowing means is arranged to face downstream in a sheet conveying direction.

10. 10. A liquid ejection apparatus comprising: a liquid ejection section that ejects liquid onto a sheet; and the drying device according to claim 1, that dries the sheet onto which the liquid has been ejected.

Images