Printing apparatus and method for controlling the printing apparatus

Abstract

To provide a printing apparatus and a control method for the printing apparatus that can reduce the time required to form an adhesive layer with a simple structure. [Solution] A printing apparatus comprising an endless conveyor belt for transporting a recording medium, a drive unit for circulating rotation of the conveyor belt, a heating unit, a printing unit for printing on the recording medium, and a control unit, wherein the control unit can select between a first mode in which, when the conveyor belt is not holding the recording medium and is circulating rotation, the heating unit heats the aqueous adhesive applied to the conveyor belt to form an adhesive layer on the conveyor belt, and a second mode in which, when the conveyor belt is circulating rotation, the heating unit heats the adhesive layer and the printing unit prints on the recording medium held by the conveyor belt.

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus and a method for controlling a printing apparatus. [Background technology]

[0002] For example, as shown in Patent Document 1, a printing apparatus is known that applies ink to a recording medium being transported on a conveyor belt to print a predetermined image pattern. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-200120 [Overview of the project] [Problems that the invention aims to solve]

[0004] An adhesive is applied to the surface of the conveyor belt. The recording medium adheres to the adhesive layer obtained by drying the adhesive, allowing the conveyor belt to hold and transport the recording medium. Generally, an organic solvent-based adhesive is used for the conveyor belt. Therefore, careful consideration must be given to the handling of the adhesive during its manufacture and application to the conveyor belt. In particular, the application of the adhesive is subject to various constraints, such as ensuring sufficient ventilation, performing the application process quickly, and limiting the composition and amount of organic solvent used. Therefore, the use of an aqueous adhesive is also being considered.

[0005] Incidentally, conventional adhesives using organic solvents are flammable and therefore cannot be heated, but they have the advantage of being highly volatile, allowing them to dry quickly and form an adhesive layer. In contrast, aqueous adhesives are less volatile than adhesives using organic solvents, so it takes a considerable amount of time for an aqueous adhesive applied to the surface of a conveyor belt to dry naturally and form an adhesive layer. However, if a mechanism for drying aqueous adhesives is newly added to the printing apparatus, it complicates the structure of the printing apparatus. [Means for solving the problem]

[0006] A printing apparatus according to an application example of the present invention is a printing apparatus that prints on a recording medium while holding the recording medium with an adhesive layer formed of an aqueous adhesive containing water and resin, An endless conveying belt for transporting the recording medium, A drive unit that rotates the aforementioned conveyor belt in a circulating manner, A heating unit installed around the aforementioned conveyor belt, A printing unit that prints on the recording medium being transported by the aforementioned conveyor belt, A control unit that controls the operation of the drive unit, the heating unit, and the printing unit, Equipped with, The control unit, In a first mode, the conveyor belt is not holding the recording medium and is rotating in a circulating manner, and the heating unit heats the aqueous adhesive applied to the conveyor belt to form the adhesive layer on the conveyor belt. In a second mode, the conveyor belt is rotating in a circulating manner, the heating unit heats the adhesive layer, and the printing unit prints on the recording medium held by the conveyor belt. It is possible to select this option.

[0007] The control method for a printing apparatus according to an application example of the present invention is: An endless conveyor belt for transporting recording media, A drive unit that rotates the aforementioned conveyor belt in a circulating manner, A heating unit installed around the aforementioned conveyor belt, A printing unit that prints on the recording medium being conveyed by the conveying belt, A control method for a printing apparatus comprising: In a state where the conveying belt does not hold the recording medium and is circulating and rotating, heating the aqueous adhesive applied to the conveying belt by the heating unit to form an adhesive layer on the conveying belt in a first step; In a state where the conveying belt is circulating and rotating, heating the adhesive layer by the heating unit in a second step of printing on the recording medium held by the conveying belt by the printing unit; It has.

Brief Description of Drawings

[0008] [Figure 1] It is a schematic configuration diagram showing a printing apparatus according to the first embodiment. [Figure 2] It is a figure which shows the state which heats a coating film, applying the coating liquid of an aqueous adhesive on the conveying belt of the printing apparatus shown in FIG. [Figure 3] It is a flowchart which shows the control method of the printing apparatus shown in FIG. [Figure 4] It is a figure which shows the state which heats the coating film on the conveying belt of the printing apparatus which concerns on a 2nd embodiment.

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description does not limit the technical scope or the meaning of terms described in the claims. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0010] <First Embodiment> First, the printing apparatus 100 according to the first embodiment will be described.

[0011] FIG. 1 is a schematic configuration diagram showing a printing apparatus 100 according to the present embodiment. FIG. 2 is a diagram showing a state in which a coating film 13 is heated while applying a coating liquid 12 of an aqueous adhesive onto a conveyance belt 111 of the printing apparatus 100 shown in FIG. 1.

[0012] Hereinafter, for convenience of explanation, in FIGS. 1 and 2, the x-axis, the y-axis, and the z-axis are illustrated as three axes orthogonal to each other. The x-axis is an axis along one direction in the horizontal direction (the width direction of the conveyance belt 111), the y-axis is an axis in the horizontal direction and along a direction perpendicular to the x-axis (the traveling direction of the portion of the conveyance belt 111 that holds the recording medium W), and the z-axis is an axis along the vertical direction (the vertical direction in the figure). Also, the tip side of each illustrated arrow is the “positive side (+ side)”, and the base end side is the “negative side (− side)”. Further, the + side in the z-axis direction is referred to as “up” or “above”, and the − side in the z-axis direction is referred to as “down” or “below”.

[0013] The printing apparatus 100 according to the present embodiment will be outlined with reference to FIG. 1. By forming an adhesive layer 11 on a conveyance belt 111 using an aqueous adhesive containing water and a resin, and adhering a recording medium W to the adhesive layer 11, the recording medium W is held on the conveyance belt 111, and the conveyance belt 111 is circulated and rotated to convey the recording medium W, and it is a printing apparatus that prints on the conveyed recording medium W.

[0014] The printing apparatus 100 includes a conveyance device 110 having a conveyance belt 111 for conveying a recording medium W, an unwinding device (uncoiler) 120 for unwinding a long, unprinted recording medium W wound in a roll shape, and a winding device (coiler) 130 for winding up the printed recording medium W. The printing apparatus 100 further includes a printing unit 140 that applies ink onto the recording medium W conveyed by the conveyance belt 111 to print a desired image pattern, an ink drying unit 150 that dries the ink on the recording medium W, and a cleaning unit 160 that cleans the adhesive layer 11 after the recording medium W is separated from the adhesive layer 11.

[0015] The adhesive strength of the adhesive layer 11 tends to gradually decrease with repeated use or washing. Therefore, the printing apparatus 100 removes the old adhesive layer 11 that has been used multiple times on the conveyor belt 111 and applies an aqueous adhesive to the conveyor belt 111 to form a new adhesive layer 11. To form the adhesive layer 11, the printing apparatus 100 further includes a coating liquid supply unit 170 that supplies an aqueous adhesive coating liquid 12 onto the conveyor belt 111, as shown in Figure 2. The coating liquid supply unit 170 includes a coating liquid supply source 170a that applies the coating liquid 12 onto the conveyor belt 111, and a blade 170b that levels the coating liquid 12 applied to the conveyor belt 111 to a desired thickness. Hereinafter, the aqueous adhesive film on the conveyor belt 111 formed by leveling the coating liquid 12 with the blade 170b will also be referred to as the "coating film 13".

[0016] The printing apparatus 100 further includes a heating unit 180 positioned around the conveyor belt 111, a control unit 191 that controls the operation of each part of the printing apparatus 100, and an operation unit 197 that receives user input. The heating unit 180 is used for both heating to dry the coating film 13 on the conveyor belt 111, as shown in Figure 2, and heating to increase the adhesive strength of the adhesive layer 11 before the recording medium W adheres to the adhesive layer 11, as shown in Figure 1.

[0017] The recording medium W, the parts of the printing apparatus 100, and the aqueous adhesive will be described in detail below. In this embodiment, the transport direction for transporting the recording medium W is the y-axis direction. In the following, the state in which the coating film 13 on the transport belt 111 is dried to form the adhesive layer 11 will also be referred to as the "first mode," and the state in which printing is performed on the recording medium W will also be referred to as the "second mode."

[0018] Furthermore, for the sake of clarity, Figures 1 and 2 show the areas where the adhesive layer 11, coating liquid 12, and coating film 13 are provided using hatching. Also, for the sake of clarity, the thicknesses of the adhesive layer 11 and coating film 13 are shown to be greater than the thickness of the conveyor belt 111, but the relative sizes of these thicknesses are not limited to those shown. In addition, in Figure 2, the unwinding device 120, winding device 130, ink drying section 150, and cleaning section 160 are omitted from the illustration. Also, in Figure 2, the tensioners 113 and 114, which will be described later, are located away from the conveyor belt 111, but their illustration is omitted.

[0019] First, let's explain the recording medium W. A material to be printed can be used as the recording medium W. A material to be printed refers to fabrics, clothing, and other fashion products that are to be printed. Fabrics include woven, knitted, and nonwoven fabrics made from natural fibers such as cotton, silk, and wool, or synthetic fibers such as polyester and nylon, or composite fibers made by mixing these. Clothing and other fashion products include T-shirts, handkerchiefs, scarves, towels, tote bags, cloth bags, curtains, sheets, bed covers and other furniture after sewing, as well as fabrics before and after cutting that exist as parts before sewing.

[0020] The recording medium W is not limited to the above-mentioned printed material, but other materials such as plain paper, fine paper, and glossy paper, which are special papers for inkjet recording, can also be used. In addition, the recording medium W can also be, for example, a plastic film that has not been surface-treated for inkjet printing, i.e., one that does not have an ink-absorbing layer, a plastic coated on a substrate such as paper, or a plastic film to which a plastic film is bonded. The plastic is not particularly limited, but examples include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

[0021] Next, the transport device 110 of the printing device 100 will be described.

[0022] As shown in Figure 1, the conveying device 110 includes a conveying belt 111, a drive unit 112 that rotates the conveying belt 111 in a circular motion, and tensioners 113 and 114 that apply tension to the recording medium W being conveyed by the conveying belt 111. The drive unit 112 includes a driving roller 112a and a driven roller 112b that are spaced apart from each other in the y-axis direction, and a motor 112c that rotates the driving roller 112a.

[0023] The conveyor belt 111 is an endless belt. The conveyor belt 111 is stretched between the driving roller 112a and the driven roller 112b. The conveyor belt 111 is flexible.

[0024] The materials used to construct the conveyor belt 111 are not particularly limited, but examples include various resin materials, various rubber materials, cloth, or resin materials or rubber materials with reinforcing members such as fiber materials embedded within them.

[0025] The adhesive layer 11 is formed on the adhesive layer forming surface 111s (also simply referred to as "on the conveyor belt 111"), which is the outer surface of the conveyor belt 111. The adhesive layer forming surface 111s of the conveyor belt 111 may be a smooth surface, but it is preferable that it be somewhat rough in order to improve adhesion with the formed adhesive layer 11. For this reason, the adhesive layer forming surface 111s may be subjected to a roughening treatment. Also, for the same purpose, the adhesive layer forming surface 111s may be subjected to a predetermined chemical treatment. Furthermore, an adhesive layer forming layer (not shown) may be provided on the outer surface of the conveyor belt 111 to obtain an ideal adhesive layer forming surface 111s. In this case, the outer surface of the adhesive layer forming layer becomes the adhesive layer forming surface 111s.

[0026] The driving roller 112a and the driven roller 112b each extend along the x-axis direction. In this embodiment, the driving roller 112a and the driven roller 112b have approximately the same diameter. However, the diameters of the driving roller and the driven roller may be different.

[0027] The driving roller 112a rotates due to the operation of the motor 112c. The driven roller 112b is positioned on the y-axis side of the driving roller 112a. The driven roller 112b receives the rotational force of the driving roller 112a via the conveyor belt 111 and rotates in conjunction with the driving roller 112a.

[0028] The motor 112c is capable of forward and reverse rotation. This allows the drive unit 112 to switch the rotation direction of the conveyor belt 111 between the state of printing on the recording medium W (second mode) and the state of forming the adhesive layer 11 on the conveyor belt 111 (first mode).

[0029] Specifically, in the second mode, as shown in Figure 1, the driving roller 112a and the driven roller 112b rotate in the first direction a1 (counterclockwise in Figure 1) with an axis parallel to the x-axis as the central axis. Therefore, the conveyor belt 111 rotates in a circular motion such that it faces the negative side in the y-axis direction when positioned above the driving roller 112a and the driven roller 112b, and faces the positive side in the y-axis direction when positioned below the driving roller 112a and the driven roller 112b.

[0030] The recording medium W unwound from the unwinding device 120 is held in the portion of the conveyor belt 111 located above the driving roller 112a and the driven roller 112b, and is conveyed in the y-axis direction. During this conveyance, the printing unit 140 prints the desired image pattern onto the recording medium W.

[0031] Furthermore, in the first mode, as shown in Figure 2, the driving roller 112a and the driven roller 112b rotate in a second direction a2 (clockwise in Figure 2), which is opposite to the first direction a1, with an axis parallel to the x-axis as the central axis. As a result, the conveyor belt 111 rotates in a circular motion together with the coating film 13, so that when it is above the driving roller 112a and the driven roller 112b, it faces the positive y-axis direction, and when it is below the driving roller 112a and the driven roller 112b, it faces the negative y-axis direction.

[0032] The driven roller 112b is provided with a rotation detection unit 115 that detects the direction and amount of rotation of the driven roller 112b. The rotation detection unit 115 is not particularly limited, but examples include optical or magnetic rotary encoders. The control unit 191 acquires information regarding the direction and amount of rotation of the driven roller 112b from the rotation detection unit 115. Based on the acquired information, the control unit 191 can determine the direction of rotation, rotation speed (conveying speed), etc., of the circulating rotation of the conveyor belt 111, and performs drive control of the conveyor belt 111 in the first mode and the second mode, respectively. Note that the installation location of the rotation detection unit is not limited to the above. For example, the rotation detection unit may be installed on the driving roller. Also, the printing device does not necessarily have to be provided with a rotation detection unit.

[0033] As described above, in the printing apparatus 100, the rotation direction of the conveyor belt 111 differs between the first mode and the second mode. However, the rotation direction of the conveyor belt may be the same between the state in which printing is performed on the recording medium and the state in which an adhesive layer is formed on the conveyor belt.

[0034] As shown in Figure 1, the tensioners 113 and 114 are each roller-shaped. Like the driving roller 112a and driven roller 112b, the tensioners 113 and 114 are spaced apart from each other in the y-axis direction and extend along the x-axis direction. The tensioners 113 and 114 are configured to move in the z-axis direction by a moving mechanism (not shown) and to move closer to and further away from the conveyor belt 111. Examples of moving mechanisms include those equipped with a drive source such as an air cylinder, an oil cylinder, or a solenoid.

[0035] In the second mode, tensioner 113 clamps the recording medium W together with the conveyor belt 111 between itself and the driving roller 112a, and tensioner 114 clamps the recording medium W together with the conveyor belt 111 between itself and the driven roller 112b. The outer surfaces of tensioners 113 and 114 are in contact with the recording medium W, and the recording medium W is conveyed in the y-axis direction and rotates clockwise in Figure 1. As a result, the recording medium W, which is subjected to appropriate tension, is held and conveyed on the conveyor belt 111 while maintaining that tension. Therefore, the occurrence of wrinkles, sagging, etc. in the recording medium W during conveyance is reduced. As a result, when printing is applied to the recording medium W, the printing will be proper and of high quality. Note that tensioners 113 and 114 may be either driving or driving rotation.

[0036] As mentioned above, although not shown in Figure 2, in the first mode, tensioners 113 and 114 are positioned in standby positions away from the conveyor belt 111 and above.

[0037] Next, the unwinding device 120 will be described. As shown in Figure 1, the unwinding device 120 is positioned upstream of the transport device 110 in the transport direction of the recording medium W, i.e., on the y-axis + side. The unwinding device 120 includes an unwinding roller (feed-out reel) 121 that has the function of winding the unprinted recording medium W into a roll and feeding out the recording medium W, a motor 122 that rotates the unwinding roller 121, and a roller-shaped tensioner 123 that applies tension to the recording medium W between the unwinding roller 121 and the transport device 110.

[0038] Motor 122 rotates the unwinding roller 121 counterclockwise in Figure 1. The recording medium W passes above the tensioner 123 and then below the tensioner 113. The position of the upper end of the tensioner 123 in the z-axis direction is higher than the position of the portion of the adhesive layer 11 that is above the drive roller 112a and the driven roller in the z-axis direction. Therefore, the recording medium W unwound from the unwinding roller 121 moves diagonally downward at the position of the tensioner 123 and adheres to the adhesive layer 11 on the conveyor belt 111 at the position of the tensioner 113.

[0039] However, the configuration of the unwinding device is not limited to the above, as long as it can unwind the recording medium. For example, the unwinding device does not need to have a tensioner, or it may have two or more tensioners, and their arrangement is not particularly limited. Also, the rotation direction of the unwinding roller is not limited to the above direction.

[0040] Next, the winding device 130 will be described. The winding device 130 is positioned downstream of the conveying device 110 in the conveying direction of the recording medium W (towards the y-axis direction). The winding device 130 includes a winding roller 131 for winding the recording medium W into a roll, a motor 132 for rotating the winding roller, and roller-shaped tensioners 133, 134, and 135 that apply tension to the recording medium W between the winding roller 131 and the conveying device 110.

[0041] Motor 132 rotates the winding roller 131 clockwise in Figure 1. Tensioners 133, 134, and 135 are arranged at predetermined intervals in this order, moving away from the winding roller 131 (towards the upstream side). The recording medium W passes below tensioner 114 and then above tensioner 135. The position of the upper end of tensioner 135 in the z-axis direction is higher than the position in the z-axis direction of the portion of the adhesive layer 11 that is above the main roller 112a and driven roller 112b. Therefore, after printing, the recording medium W moves diagonally upward at the position of tensioner 114, separating from the adhesive layer 11 and the conveyor belt 111.

[0042] However, the configuration of the winding device is not limited to the above, as long as it can wind up the recording medium. For example, the winding device does not need to have a tensioner, and the number of tensioners provided in the winding device may be one, two, or four or more, and their arrangement is not particularly limited. Also, the rotation direction of the winding roller is not limited to the above direction.

[0043] Next, we will explain the printing unit 140. The printing unit 140 includes a carriage unit 142 having a plurality of inkjet heads 141 that eject ink toward the recording medium W, and an x-axis table (not shown) that supports the carriage unit 142 so as to be movable in the x-axis direction.

[0044] Each inkjet head 141 includes, for example, a head body with an internal flow channel filled with ink, and a group of nozzles having openings. The head body is provided with a piezoelectric element (piezoelectric body) corresponding to each ejection nozzle, and when a voltage is applied to the piezoelectric element, ink is ejected from the group of nozzles as droplets.

[0045] The ink contains a dye or pigment as a coloring agent in water as a solvent, and comes in four colors, such as cyan (C), magenta (M), yellow (Y), and black (K). Each color of ink is ejected independently from the inkjet head 141.

[0046] In the state for printing on the recording medium W (second mode), the carriage unit 142 is positioned above the portion of the recording medium W that is held by the conveyor belt 111. The unwinding device 120 intermittently feeds out the recording medium W while it is held by the conveyor belt 111. At this time, the printing unit 140 ejects ink from the nozzle group while the carriage unit 142 reciprocates in the x-axis direction against the held recording medium W. As a result, the desired image pattern is formed on the recording medium W and printing is performed. The image pattern may be multi-color printed or monochrome printed.

[0047] In this way, a printing area 144 is formed between the printing unit 140 and the conveyor belt 111. More specifically, the printing area 144 is located between the lower part of the carriage unit 142 and the area of ​​the outer surface of the adhesive layer 11 that is located between the tensioner 113 and the tensioner 114.

[0048] In states where no printing is being done on the recording medium W, such as when forming the adhesive layer 11 (first mode), the carriage unit 142 is waiting in a standby position, which is located away from the recording medium W (conveyor belt 111) in the x-axis direction when viewed from the z-axis direction.

[0049] However, the configuration of the printing unit is not limited to the above, as long as it can print on a recording medium. For example, the inkjet head may be a thermal type instead of a piezo type. Also, the printing unit may not use an inkjet head, for example, a transfer type printing method.

[0050] Next, we will explain the ink drying section 150. The ink drying unit 150 is located downstream of the printing unit 140 in the transport direction of the recording medium W (y-axis direction), and is positioned between the transport device 110 and the winding roller 131 of the winding device 130. The ink drying unit 150 includes a chamber 151 and a coil 152, which is a heat source (heater), located inside the chamber 151. The coil 152 is made of a heating element that generates heat when power is supplied to it, such as a nichrome wire. The heat generated by the coil 152 dries the ink on the recording medium W as it passes through the chamber 151.

[0051] However, the configuration of the ink drying unit is not limited to the above, as long as it can dry the ink on the recording medium. For example, the ink drying unit may be composed of other heaters such as sheath heaters, cartridge heaters, or infrared heaters. Furthermore, the printing device does not need to have an ink drying unit.

[0052] Next, the cleaning unit 160 will be described. The cleaning unit 160 is located below the conveyor belt 111 and the driven roller 112b. The cleaning unit 160 includes a storage tank 161 for storing cleaning fluid and a cleaning brush 162 located inside the storage tank 161. The cleaning brush 162 is configured to rotate by a motor (not shown). The cleaning unit 160 is configured to move in the z-axis direction by a moving mechanism (not shown) and to move toward and away from the conveyor belt 111. Examples of moving mechanisms include those equipped with a drive source such as an air cylinder, an oil cylinder, or a solenoid.

[0053] In the state where printing is performed on the recording medium W (second mode), the cleaning unit 160 is positioned so that the cleaning brush 162 contacts the adhesive layer 11 on the conveyor belt 111. As the cleaning brush 162 rotates, cleaning liquid is applied to the surface of the adhesive layer 11 after the recording medium W has separated, and the adhesive layer 11 is brushed. This removes foreign matter such as ink composition and fibers from the recording medium W that have adhered to the adhesive layer 11.

[0054] In the state where the adhesive layer 11 is formed (first mode), the cleaning unit 160 is in an inactive state. That is, the cleaning unit 160 is positioned in a standby position where the rotation of the cleaning brush 162 is stopped and it is separated from the conveyor belt 111 and the coating 13.

[0055] However, the configuration of the cleaning unit is not limited to the above, as long as the adhesive layer can be cleaned when necessary. For example, the cleaning unit may be configured to spray cleaning fluid from a nozzle onto the adhesive layer by operating a pump, thereby cleaning the adhesive layer. Alternatively, the cleaning unit may be configured to remove foreign matter by sliding a blade or brush against the adhesive layer. Furthermore, the printing apparatus may not even be provided with a cleaning unit.

[0056] Next, the aqueous adhesive that constitutes the coating solution 12 will be described. Aqueous adhesives are aqueous adhesive compositions containing resin and water. The constituent materials and physical properties of aqueous adhesives are described in detail below.

[0057] [resin] The resin is not particularly limited, but for example, (meth)acrylic resins can be used.

[0058] By including a (meth)acrylic resin, the adhesive strength and durability of the adhesive layer 11 can be improved. The (meth)acrylic resin may be a water-soluble resin or an emulsion dispersed in an aqueous solvent. In this embodiment, these are collectively referred to as (meth)acrylic resin. By using a (meth)acrylic resin, the environmental burden caused by organic solvents can be reduced, and the peelability of the recording medium W, especially the fabric, from the adhesive layer 11 tends to be further improved.

[0059] The (meth)acrylic resin is not particularly limited as long as it is a polymer obtained by polymerizing a (meth)acrylic monomer such as (meth)acrylic acid or (meth)acrylic acid ester as one component. Examples include homopolymers obtained from (meth)acrylic monomers and copolymers of (meth)acrylic monomers and other monomers. More specific examples of (meth)acrylic monomers are not particularly limited, but include (meth)acrylic monomers having aliphatic groups with 3 or fewer carbon atoms, such as methyl methacrylate (MMA), ethyl methacrylate (EMA), and n-propyl methacrylate (PMA); (meth)acrylic monomers having aliphatic groups with 4 or more carbon atoms, such as butyl methacrylate (BMA), butyl acrylate (BA), and 2-ethylhexyl acrylate (2EHA); and (meth)acrylic monomers having aromatic groups, such as styrene (St). Other monomers are not particularly limited, but examples include acrylamide and acrylonitrile.

[0060] The monomers contained in (meth)acrylic resins are not particularly limited, but examples include methyl methacrylate (MMA), ethyl methacrylate (EMA), n-propyl methacrylate (PMA), butyl methacrylate (BMA), styrene (St), butyl acrylate (BA), and 2-ethylhexyl acrylate (2EHA).

[0061] The monomer combinations are not particularly limited, but examples include those containing at least ethyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate; those containing at least methyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate; those containing at least n-propyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate; and those containing at least butyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate.

[0062] The aqueous adhesive composition contains at least a first (meth)acrylic resin and a second (meth)acrylic resin as the (meth)acrylic resin, and it is preferable that the glass transition temperature Tg1 of the first (meth)acrylic resin is higher than the glass transition temperature Tg2 of the second (meth)acrylic resin. By including two (meth)acrylic resins having such different glass transition temperatures Tg, the adhesive strength, durability, and the effect of suppressing the decrease in adhesive strength during brushing tend to be further improved.

[0063] The glass transition temperature Tg1 of the first (meth)acrylic resin is not particularly limited, but is preferably between -25°C and 25°C, and more preferably between -20°C and 20°C. When the glass transition temperature Tg1 is within the above range, the adhesive strength tends to improve.

[0064] The glass transition temperature Tg2 of the second (meth)acrylic resin is not particularly limited, but is preferably between -70°C and -15°C, and more preferably between -65°C and -20°C. When the glass transition temperature Tg2 is within the above range, the decrease in adhesive strength during brushing tends to be further suppressed.

[0065] The difference between the glass transition temperature Tg1 and the glass transition temperature Tg2, |Tg1-Tg2|, is preferably between 10°C and 50°C, and more preferably between 15°C and 45°C. When the difference |Tg1-Tg2| is within the above range, the adhesive strength and the effect of suppressing the decrease in adhesive strength during brushing tend to be further improved.

[0066] The glass transition temperature can be adjusted by the homopolymer glass transition temperature of the polymerizable compound used and the weight ratio of the polymerizable compound used. The glass transition temperature can be measured by conventionally known methods.

[0067] The monomers included in the first (meth)acrylic resin are not particularly limited, but it is preferable that they include at least ethyl methacrylate, butyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate; at least ethyl methacrylate, styrene, butyl acrylate, and 2-ethylhexyl acrylate; at least methyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate; or at least butyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate. Using the first (meth)acrylic resin containing the above monomers tends to further improve adhesive strength and the effect of suppressing the decrease in adhesive strength during brushing.

[0068] The first (meth)acrylic resin described above preferably contains a (meth)acrylic monomer as a constituent unit, the homopolymer having a glass transition temperature of 40°C or higher. The inclusion of the above monomer in the first (meth)acrylic resin tends to further improve the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing.

[0069] The content of (meth)acrylic monomers having a homopolymer glass transition temperature of 40°C or higher is preferably 20% to 70% by weight, and more preferably 25% to 65% by weight, relative to the total amount of the first (meth)acrylic resin. When the content of (meth)acrylic monomers having a homopolymer glass transition temperature of 40°C or higher is within the above range, the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing tend to be further improved.

[0070] The monomers included in the second (meth)acrylic resin are not particularly limited, but it is preferable that they include at least ethyl methacrylate, butyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate, or at least n-propyl methacrylate, butyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate. Using the second (meth)acrylic resin containing the above monomers tends to further improve adhesive strength and the effect of suppressing the decrease in adhesive strength during brushing.

[0071] The content of the first (meth)acrylic resin is preferably 50% to 85% by weight, and more preferably 53% to 82% by weight, relative to the total amount of the first (meth)acrylic resin and the second (meth)acrylic resin. When the content of the first (meth)acrylic resin is within the above range, the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing tend to be further improved.

[0072] The content of the second (meth)acrylic resin is preferably less than 50% by weight, and more preferably 10% by weight or more and 48% by weight or less, relative to the total amount of the first (meth)acrylic resin and the second (meth)acrylic resin. When the content of the second (meth)acrylic resin is within the above range, the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing tend to be further improved.

[0073] The content of (meth)acrylic resin is preferably 20% to 70% by weight, and more preferably 30% to 60% by weight, relative to the total amount of the aqueous adhesive composition (coating liquid 12). When the (meth)acrylic resin content is 20% by weight or more, the adhesive strength and durability of the resulting adhesive layer 11 tend to be further improved. Furthermore, when the (meth)acrylic resin content is 70% by weight or less, the applicability and storage properties of the aqueous adhesive composition tend to be further improved. Note that the resin content relative to the total amount of the aqueous adhesive composition refers to the amount of solids.

[0074] The content of the first (meth)acrylic resin is preferably 10% to 70% by weight, and more preferably 20% to 60% by weight, relative to the total amount of the aqueous adhesive composition (coating liquid 12). When the content of the first (meth)acrylic resin is within the above range, the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing tend to be further improved.

[0075] The content of the second (meth)acrylic resin is preferably 50% by weight or less, and more preferably 1% by weight or more and 40% by weight or less, relative to the total amount of the aqueous adhesive composition (coating liquid 12). When the content of the second (meth)acrylic resin is within the above range, the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing tend to be further improved.

[0076] The aqueous adhesive composition may contain resins other than (meth)acrylic resins. Such other resins are not particularly limited, but examples include urethane resins, silicone resins, and various elastomers (rubber-based materials). Furthermore, the resin is not limited to the above-mentioned (meth)acrylic resin or a composition primarily composed of (meth)acrylic resins; other examples include urethane resins, silicone resins, and various rubber-based materials.

[0077] [Tackifier] The aqueous adhesive composition preferably contains no or only a small amount of tackifier. When no or only a small amount of tackifier is present, the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing tend to be more sustained. Typical examples of such tackifiers include rosin compounds, terpene compounds, and hydrocarbon resins. More specifically, examples include rosin compounds such as natural rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, and pentaerythritol ester of modified rosin; terpene compounds such as copolymers of natural terpenes, three-dimensional polymers of natural terpenes, aromatically modified terpene resins, hydrogenated derivatives of aromatically modified terpene resins, terpene phenol resins, and terpene resins (monoterpenes, diterpenes, triterpenes, polypertenes, etc.); and hydrocarbon resins such as aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, styrene oligomers, aromatic petroleum hydrocarbon resins (C9 resins), and hydrogenated derivatives of aromatic petroleum hydrocarbon resins.

[0078] It is preferable that the tackifier is either not contained or contained in small amounts. If a tackifier is contained, its content is not particularly limited, but is preferably 5% by weight or less, more preferably 4% by weight or less, and even more preferably 0.1% by weight or more and 3.8% by weight or less, relative to the total amount of the aqueous adhesive composition (coating liquid 12). When the tackifier content is within the above range, the adhesive strength of the resulting adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing tend to be sustained. From a similar viewpoint, it is preferable that the total content of compounds selected from the group consisting of rosin compounds, terpene compounds, and hydrocarbon resins is also within the same range as above.

[0079] [water] The water content (moisture content) in the aqueous adhesive composition (coating liquid 12) is not particularly limited, but is preferably 30% by weight or more and 80% by weight or less, more preferably 35% by weight or more and 70% by weight or less, and even more preferably 40% by weight or more and 60% by weight or less. This makes it easier to level the coating liquid 12 applied to the adhesive layer forming surface 111s to a uniform thickness.

[0080] [Surfactants] The aqueous adhesive composition may contain a surfactant. The surfactant is not particularly limited, but examples include anionic surfactants, nonionic surfactants, and cationic surfactants.

[0081] Examples of anionic surfactants include alkyl sulfocarboxylates, alkyl diphenyl ether disulfonates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acyl amino acids and their salts, N-acyl methyl taurates, alkyl sulfates such as ammonium lauryl sulfate and sodium lauryl sulfate, alkyl sulfate polyoxyalkyl ether sulfates, alkyl sulfate polyoxyethylene alkyl ether phosphates, rosinic acid soaps, castor oil sulfates, lauryl alcohol sulfates, alkylphenol type phosphates, alkyl type phosphates, alkylaryl sulfonates, diethyl sulfosaturates, diethylhexyl sulfosaturates, and dioctyl sulfosaturates.

[0082] Examples of nonionic surfactants include acetylene glycol surfactants, silicone surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil, propylene glycol fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, alkyl polyglycosides, alkyldiethanolamides, and alkylamine oxides. Examples of commercially available nonionic surfactants are not particularly limited, but include Emulgen 123P, 430, 1108 (product names of Kao Corporation), Newcol 1006, 1008, 1020 (product names of Nippon Emulsifier Co., Ltd.), and Neugen DL-0415, ET-116B, ET-106A, DH-0300, YX-400, EA-160 (product names of Daiichi Kogyo Seiyaku Co., Ltd.).

[0083] Cationic surfactants include alkylamine salts, fatty acid amidoamine salts, monoalkyl quaternary ammonium salts, dialkyl quaternary ammonium salts, trialkyl quaternary ammonium salts, benzalkonium quaternary ammonium salts, benzethonium chloride, and alkylpyridinium salts.

[0084] In this embodiment, nonionic surfactants are preferred among these, and more specifically, alkyl ether-based nonionic surfactants are preferred. Using such surfactants tends to maintain durability.

[0085] The surfactant content is preferably 1% by weight or more and 7% by weight or less, and more preferably 2% by weight or more and 6% by weight or less, relative to the total amount of the aqueous adhesive composition (coating liquid 12).

[0086] [organic solvent] In this embodiment, the aqueous adhesive composition preferably contains no organic solvent or only a small amount of it, from the viewpoint of reducing environmental impact and impact on the human body. Furthermore, if an organic solvent is included, the content of the organic solvent is preferably 5.0% by weight or less, and more preferably 2.5% by weight or less, relative to the total amount of the aqueous adhesive composition (coating liquid 12). This reduces the environmental impact and the amount of VOCs (volatile organic compounds) when using the aqueous adhesive composition, which tends to improve the working environment.

[0087] [Colorants] In this embodiment, the aqueous adhesive composition preferably contains no colorant or only a small amount of colorant. If a colorant is included, the colorant content is preferably 1.0% by weight or less, and more preferably 0.5% by weight or less, relative to the total amount of the aqueous adhesive composition (coating liquid 12). This clearly distinguishes the aqueous adhesive composition of this embodiment from compositions intended for coloring, such as ink compositions, printing pastes, and paints.

[0088] [Storage modulus] The aqueous adhesive composition in this embodiment is a raw material for forming an adhesive layer 11 on the conveyor belt 111 of the printing apparatus 100. Despite being derived from an aqueous adhesive composition, the adhesive layer 11 in this embodiment has the necessary and sufficient adhesive strength to convey the recording medium W while holding it, and also has excellent durability, i.e., the persistence of its adhesive strength. As a result, the conveyor belt 111 can convey the recording medium W while securely holding it. Therefore, printing defects (malfunctions) such as misalignment of the print caused by poor holding or poor conveyance of the recording medium W are suppressed, and proper and good printing can be achieved. Furthermore, this effect is maintained for a long period of time. Such an adhesive layer 11 has the following characteristics and physical properties.

[0089] The storage modulus of the adhesive layer 11 obtained in this embodiment at 23°C is 1.5 × 10⁻⁶ 5 Pa or more 5.0×10 5 It is preferable that it is less than or equal to Pa, and 1.6 × 10 5 Pa or more 4.8×105 It is more preferably below Pa, and 2.0×10 5 Pa or more and 4.5×10 5 It is even more preferably below Pa. When the storage elastic modulus is 1.5×10 5 Pa or more, it is possible to suppress the decrease in adhesive force due to washing the adhesive surface with water. Also, when the storage elastic modulus is 5.0×10 5 Pa or less, the initial adhesive force can be increased.

[0090] The method for forming the adhesive layer 11 for measuring the storage elastic modulus is not particularly limited. For example, an aqueous adhesive composition is applied to a 25 mm wide slide glass at room temperature to a thickness of 0.2 mm and dried under conditions of 50% humidity, 23°C, and for 12 hours.

[0091] When forming an adhesive layer 11 (hereinafter referred to as "the first acrylic adhesive layer") consisting only of the first (meth)acrylic resin by the same method as the aqueous adhesive composition, the storage elastic modulus of the first acrylic adhesive layer at 23°C is not particularly limited, but is preferably 1.0×10 5 Pa or more and 8.0×10 5 Pa or less, and more preferably 1.6×10 5 Pa or more and 7.6×10 5 Pa or less. When the storage elastic modulus of the first acrylic adhesive layer is within the above range, the adhesive force of the adhesive layer 11 and the effect of suppressing the decrease in adhesive force during brushing tend to be further improved.

[0092] When forming an adhesive layer 11 (hereinafter referred to as "the second acrylic adhesive layer") consisting only of the second (meth)acrylic resin by the same method as the aqueous adhesive composition, the storage elastic modulus of the second acrylic adhesive layer at 23°C is not particularly limited, but is preferably 6.0×10 5 or more and 8.0×10 5 Pa or less, and more preferably 7.0×10 5 or more and 7.5×10 5It is more preferable that the storage modulus of the second acrylic adhesive layer is within the above range, which tends to further improve the adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing.

[0093] [Adhesive strength] The adhesive strength of the adhesive layer 11 obtained by this embodiment at room temperature (23°C) is not particularly limited, but is preferably 0.3 N / 50 mm or more and 3.0 N / 50 mm or less, more preferably 0.5 N / 50 mm or more and 2.0 N / 50 mm or less, and even more preferably 0.7 N / 50 mm or more and 1.8 N / 50 mm or less. Having the adhesive strength at 23°C within the above range further improves the good adhesive strength of the adhesive layer 11 and the effect of suppressing the decrease in adhesive strength during brushing.

[0094] [viscosity] The viscosity of the coating liquid 12 used to form the adhesive layer 11 at room temperature (23°C) is not particularly limited, but is preferably 1 cps or more and 500 cps or less, more preferably 5 cps or more and 470 cps or less, even more preferably 100 cps or more and 450 cps or less, and particularly preferably 120 cps or more and 400 cps or less. This makes it easier to level the coating liquid 12 applied to the adhesive layer forming surface 111s to a uniform thickness, contributing to the uniformity of the thickness and surface properties of the resulting adhesive layer 11.

[0095] [thickness] The average thickness of the adhesive layer 11 formed on the conveyor belt 111 is not particularly limited, but is preferably 0.03 mm to 7.0 mm, more preferably 0.08 mm to 1.0 mm, and even more preferably 0.1 mm to 0.5 mm. By setting the average thickness of the adhesive layer 11 within the above range, the adhesive strength of the adhesive layer 11 can be improved and its durability can be increased. Furthermore, when forming the adhesive layer 11 using the coating liquid 12, a uniform and homogeneous adhesive layer 11 with good adhesion to the adhesive layer forming surface 111s can be formed relatively easily.

[0096] Next, the coating liquid supply source 170a of the coating liquid supply unit 170 will be described. As shown in Figure 2, the coating liquid supply source 170a applies a water-based adhesive coating liquid 12 to the area of ​​the adhesive layer forming surface 111s of the conveyor belt 111 that is located above the active roller 112a and the driven roller 112b. The coating liquid supply source 170a includes a storage section 171 for storing the coating liquid 12, a liquid delivery pipe 172 for delivering the coating liquid 12 from the storage section 171 to the vicinity of the adhesive layer forming surface 111s of the conveyor belt 111, and a liquid delivery pump 173 provided in the middle of the liquid delivery pipe 172.

[0097] The storage section 171 is made up of a rigid or flexible container capable of holding the coating liquid 12. The upper end (one end) of the liquid delivery pipe 172 is connected to the storage section 171. The lower end (the other end) of the liquid delivery pipe 172 is located above the adhesive layer forming surface 111s of the conveyor belt 111 and downstream of the printing section 140 in the conveying direction of the recording medium W (y-axis direction). When the liquid delivery pump 173 is operated, the coating liquid 12 in the storage section 171 is delivered through the liquid delivery pipe 172 and discharged from the lower end of the liquid delivery pipe 172 toward the adhesive layer forming surface 111s of the conveyor belt 111.

[0098] The lower end of the liquid delivery pipe 172 branches into multiple channels, although this is not shown in the diagram. The branched channels are aligned along the x-axis, that is, along the width direction of the conveyor belt 111. This allows the coating liquid 12 to be supplied evenly (without excess or deficiency) to the required area of ​​the adhesive layer forming surface 111s. The lower end of the liquid delivery pipe 172 may be provided with a nozzle, orifice, etc.

[0099] The amount of coating liquid 12 supplied per unit time from the liquid supply pipe 172 to the adhesive layer forming surface 111s, i.e., the sum of the amounts supplied in each branch channel (hereinafter simply referred to as "supply amount"), is not particularly limited, but is preferably 15 ml / min or more and 67 ml / min or less, and more preferably 22 ml / min or more and 50 ml / min or less. By using such a supply amount, the coating liquid 12 can be applied quickly, and the coating film 13 can be leveled more uniformly and effectively by the blade 170b.

[0100] The coating liquid supply source 170a may be configured to continuously supply the coating liquid 12, or it may be configured to supply it intermittently.

[0101] The configuration and method for applying the aqueous adhesive to the conveyor belt are not limited to those described above. For example, the storage section may be a flexible container, and the coating liquid supply source may have a pressurizing section that pressurizes the storage section from the outside. In this case, the pressurizing section pressurizes the storage section, pushing the coating liquid in the storage section into the liquid supply pipe. The coating liquid is then discharged from the lower end of the liquid supply pipe and applied to the conveyor belt. Examples of pressurizing sections include those that pressurize the storage section with air pressure, and those that physically pressurize using components such as pressurizing plates or pressure rollers. The coating liquid supply source may also be configured to supply the coating liquid in the storage section to the conveyor belt by free fall via the liquid supply pipe. Furthermore, the printing device may not have a coating liquid supply source, and the coating liquid may be applied to the conveyor belt by, for example, an external coating liquid supply source. Moreover, the coating liquid supply source itself may not exist, regardless of whether it is included in the printing device or not. In this case, the aqueous adhesive can be applied to the conveyor belt by methods such as an operator applying the aqueous adhesive to the conveyor belt using an application tool.

[0102] Next, I will explain blade 170b. The blade 170b smooths the coating liquid 12 supplied to the adhesive layer forming surface 111s by the coating liquid supply source 170a while the conveyor belt 111 is rotating in a circular motion. In other words, the blade 170b functions as a squeegee. The blade 170b is elongated and extends in the width direction of the conveyor belt 111. The blade 170b forms a coating film 13 of generally uniform thickness.

[0103] The blade 170b may be rigid or flexible. The constituent material of the blade 170b is not particularly limited, but examples include various metal materials, various ceramic materials, various resin materials, various rubber materials, or resin materials or rubber materials with reinforcing members such as fiber materials embedded within them.

[0104] The blade 170b is configured to be movable in the z-axis direction by a moving mechanism (not shown). Examples of such moving mechanisms include those equipped with a drive source such as an air cylinder, an oil cylinder, or a solenoid.

[0105] When leveling the coating liquid 12 supplied from the coating liquid supply source 170a to form a coating film 13, the blade 170b is positioned above the conveyor belt 111. More specifically, the blade 170b is located between the lower end of the liquid supply pipe 172 and the printing unit 140, that is, upstream of the lower end of the liquid supply pipe 172 in the conveying direction of the recording medium W (y-axis + side) and downstream of the printing unit 140 in the conveying direction of the recording medium W (y-axis - side).

[0106] On the other hand, as shown in Figure 1, in states where the coating liquid 12 is not leveled, such as when printing on the recording medium W (second mode) or when the coating film 13 has been formed, the blade 170b moves to a retracted position above the conveyor belt 111. However, the printing device may not be provided with a blade movement mechanism, and the operator may attach or detach the blade to the conveyor as needed.

[0107] As shown in Figure 2, when leveling the coating liquid 12 to form the coating film 13, the lower end (the end on the z-axis side) of the blade 170b is spaced a predetermined distance G from the adhesive layer forming surface 111s. This distance G is one important factor in determining the thickness of the adhesive layer 11. The distance G is determined appropriately according to various conditions such as the composition, viscosity, supply amount of the coating liquid 12 and the adhesive strength of the target adhesive layer 11. If at least one, particularly two or three of the viscosity, supply amount, and adhesive strength of the coating liquid 12 are within the preferred ranges described above, the distance G is preferably 0.05 mm to 5 mm, and more preferably 0.1 mm to 0.5 mm. This makes it possible to form a coating film 13 with a more uniform thickness.

[0108] It is preferable that this distance G is approximately equal along the longitudinal direction of the blade 170b, i.e., along the x-axis direction. This makes it possible to make the thickness of the coating 13 uniform in the x-axis direction.

[0109] The length of the blade 170b in the width direction (x-axis direction) of the conveyor belt 111 is not particularly limited, but is preferably 50 cm or more and 300 cm or less, and more preferably 100 cm or more and 200 cm or less. This allows the length of the blade 170b in the width direction of the conveyor belt 111 to be equal to or longer than the width of the conveyor belt 111, regardless of the model of the printing device 100 or the size of the conveyor belt 111. Thus, the blade 170b can cover the entire width direction or effective area of ​​the conveyor belt 111, and the coating liquid 12 can be evenly distributed.

[0110] The configuration and method for leveling (forming a coating film) the aqueous adhesive coating on the conveyor belt are not limited to those described above. For example, the printing apparatus may be equipped with other leveling tools such as a squeegee, roller, brush, or air knife instead of a blade. Alternatively, the printing apparatus may not be equipped with leveling tools such as a blade, and the operator may level the coating on the conveyor belt using a squeegee, roller, brush, or other tool.

[0111] Next, the heating section 180 will be described. The heating unit 180 is located on the outer circumference of the conveyor belt 111. More specifically, as shown in Figures 1 and 2, the heating unit 180 is located directly below the conveyor belt 111 and is positioned on the positive y-axis side of the cleaning unit 160. The heating unit 180 is separated from the adhesive layer forming surface 111s of the conveyor belt 111, and further separated from the coating film 13 and adhesive layer 11 formed thereon, and is in non-contact with all of them. Therefore, when heating the coating film 13 and adhesive layer 11, damage to the coating film 13 and adhesive layer 11 or adhesion of dirt to them can be suppressed.

[0112] The heating unit 180 includes a radiating plate 181, a heat source 182 for heating the radiating plate 181, and a frame 183 as a base for fixing the radiating plate 181 and the heat source 182.

[0113] The radiating plate 181 extends along the width direction (x-axis direction) of the conveyor belt 111. The length of the radiating plate 181 in the width direction is longer than the length of the conveyor belt 111 in the width direction. Both ends of the radiating plate 181 in the width direction protrude from the conveyor belt 111 in the width direction (x-axis direction + side and - side) when viewed from above. The constituent material of the radiating plate 181 is not particularly limited, but examples include various metal materials such as aluminum or aluminum alloys, copper or copper alloys, and iron alloys such as stainless steel. Alternatively, the radiating plate 181 may be made by bonding a metal layer to a heat-resistant material such as ceramic material or glass.

[0114] The heat source 182 is joined to the lower surface of the radiating plate 181 by adhesive or the like. In this embodiment, the heat source 182 is composed of a sheet heater. The sheet heater is constructed by sandwiching a heating element such as metal foil inside a sheet member made of a flexible synthetic resin or the like. The heat source 182 extends along the width direction of the conveyor belt 111. The length of the heat source 182 in the width direction is longer than the length of the conveyor belt 111 in the width direction. Both ends of the heat source 182 in the width direction protrude from the conveyor belt 111 in the width direction (+ and - sides in the x-axis direction) when viewed from above.

[0115] The heat source 182 generates heat when power is supplied to its heating element, and this heat is transferred to the radiating plate 181. The radiating plate 181 heats up as heat is transferred from the heat source 182. The heated radiating plate 181 emits radiant heat toward the conveyor belt 111.

[0116] In the state in which the adhesive layer 11 is formed (first mode), the heating unit 180 heats the coating film 13 on the conveyor belt 111. As a result, the coating film 13 on the conveyor belt 111 dries and the adhesive layer 11 is formed. Here, "drying" is synonymous with "removal of water" or "dehydration," and refers to reducing the water content of the coating film 13. In this specification, the "adhesive layer 11" means the coating film 13 from which at least a portion of the water has evaporated, i.e., the water content has been reduced, and some water may remain in the adhesive layer 11.

[0117] The moisture content of the adhesive layer 11 after heating and drying by the heating unit 180 is not particularly limited, but is preferably 0.01% by weight or more and 5% by weight or less, more preferably 0.1% by weight or more and less than 2% by weight, and even more preferably 0.5% by weight or more and less than 1% by weight. By keeping the moisture content of the adhesive layer 11 below the above upper limit, adhesion of the adhesive layer 11 to the recording medium W can be suppressed. By keeping the moisture content of the adhesive layer 11 above the above lower limit, hardening of the adhesive layer 11 can be suppressed, making it easier to adhere the adhesive layer 11 to the recording medium W.

[0118] On the other hand, in the state where printing is performed on the recording medium W (second mode), the heating unit 180 heats the adhesive layer 11 on the conveyor belt 111. This causes the adhesive layer 11 to soften appropriately, making it easier to adhere to the recording medium W. As a result, the adhesive force of the adhesive layer 11 to the recording medium W increases, and good retention of the recording medium W is achieved.

[0119] However, the configuration of the heating unit is not limited to the above, as long as it can heat the coating and adhesive layer. For example, the heating unit may not have a radiating plate. Also, instead of a sheet heater, a rod heater, or an infrared heater such as a sheathed heater, cartridge heater, or ceramic heater may be used as the heat source for the heating unit.

[0120] Furthermore, the position of the heating element is not limited to the position shown in the figure. In the second mode, the heating element can be positioned to heat the adhesive layer before the recording medium adheres, and in the first mode, it can be positioned to heat the coating film. For example, the heating element may be positioned on the y-axis + side of the main roller. Alternatively, the heating element may be positioned inside the conveyor belt, heating the adhesive layer and coating film via the conveyor belt. Alternatively, the heating element may be provided in an arc shape, wrapping around from the y-axis + side of the main roller to below the main roller. By positioning at least a part of the heating element on the y-axis + side of the main roller, the viscosity of the coating film increases on the y-axis - side of the main roller, ensuring shape retention. Therefore, when the coating film wraps around the outer circumference of the main roller downwards, dripping from the coating film and deformation of the coating film due to gravity can be suppressed.

[0121] In this embodiment, the heating unit 180 is fixedly installed on the conveying device 110, but this is not limited to this configuration. For example, the heating unit may be movable along the rotational direction of the conveying belt (e.g., the y-axis direction, the z-axis direction). In this case, the printing device may be provided with a moving mechanism for moving the heating unit, and the position of the heating unit, for example, the position in the y-axis direction or the z-axis direction, may be set by the operation of this moving mechanism to suit heating in the first mode and the second mode, respectively. Examples of moving mechanisms include those equipped with a drive source such as an air cylinder, an oil cylinder, or a solenoid.

[0122] Next, the control unit 191 will be described. The control unit 191 is electrically connected to the drive unit 112, rotation detection unit 115, unwinding device 120, winding device 130, printing unit 140, ink drying unit 150, cleaning unit 160, coating liquid supply unit 170, heating unit 180, and operation unit 197 of the transport device 110, respectively. It transmits and receives signals between these units to control their operation and acquire information. The control unit 191 includes a storage unit 192, an arithmetic processing unit 193, and a communication unit 194. The control unit 191 also has a built-in clock (timer) and may control the operating timing of each part of the printing device 100.

[0123] The memory unit 192 stores programs for operating each part of the printing device 100, information regarding operating conditions, and the like. Examples of the memory unit 192 include volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory).

[0124] The arithmetic processing unit 193 is composed of a processor such as a CPU (Central Processing Unit), and reads and executes various programs, such as operation programs, stored in the memory unit.

[0125] The communication unit 194 is an interface for sending and receiving signals to and from each part of the printing device 100. The communication unit 194 is connected to each part of the printing device 100 by wire or wireless.

[0126] The control unit 191 can select between a first mode for forming the adhesive layer 11 and a second mode for printing on the recording medium W. Details of the control method in each mode will be described later.

[0127] Next, the operating unit 197 will be described. The control unit 197 is comprised of a touch panel that also functions as a display unit. The control unit 197 displays a selection screen for the first mode and the second mode. The user operates the control unit 197 to select the first mode if they want to form the adhesive layer 11, or to select the second mode if they want to print on the recording medium W. The control unit 191 controls each part according to the mode selected by the user on the control unit 197.

[0128] However, the configuration of the control unit is not limited to the above. For example, the selection screen for the first and second modes may be displayed on a display unit such as an LCD panel, and the control unit may be configured with separate operation buttons, a keyboard and mouse, etc., from the display unit. Alternatively, the control unit may have physical operation buttons or switches that can switch between each mode. Furthermore, the control unit may be configured to select the first and second modes by recognizing the voice spoken by the user.

[0129] Furthermore, the printing unit may not have an operating unit, and the system may be configured so that the selection of the first or second mode is performed automatically or according to a predetermined program (sequence control) by the control unit or an external device capable of communicating with the control unit. For example, such a configuration may include a control unit that has a built-in clock and selects (switches) between the first and second modes based on a predetermined timing chart.

[0130] Next, the control method for the printing device 100 will be described. Figure 3 is a flowchart showing the control method for the printing device 100 shown in Figure 1.

[0131] The control method for the printing apparatus 100 includes a first step S1 for forming an adhesive layer 11 and a second step S2 for printing on a recording medium W. The first step S1 corresponds to a first mode, and the second step S2 corresponds to a second mode.

[0132] Before the first step S1 in which the adhesive layer 11 is formed, the old adhesive layer 11 on the conveyor belt 111 is removed in advance. Also, as shown in Figure 2, the conveyor belt 111 is not holding the recording medium W, and the blade 170b is positioned above the conveyor belt 111. The user operates the control unit 197 to select the first mode.

[0133] This enables the first step S1, which forms the adhesive layer 11. Specifically, the control unit 191 rotates the main roller 112a in the second direction a2 by operating the drive unit 112 of the conveying device 110, causing the conveying belt 111 to circulate clockwise in Figure 2, while supplying the aqueous adhesive coating liquid 12 onto the conveying belt 111 by operating the coating liquid supply source 170a.

[0134] The supplied coating liquid 12 passes through the gap between the lower end of the blade 170b and the adhesive layer forming surface 111s to form a coating film 13. This coating film 13 moves in the y-axis direction + as the conveyor belt 111 moves, wraps around the outer circumference of the main roller 112a downwards, and then passes above the heating section 180 in the y-axis direction -. The coating film 13 is allowed to air dry to some extent between passing the lower end of the blade 170b and moving in the y-axis direction + as it wraps around the outer circumference of the main roller 112a. This increases the viscosity of the coating film 13, ensuring shape retention, and thus suppresses dripping from the coating film 13 and deformation of the coating film 13 due to gravity before it reaches the heating section 180.

[0135] The control unit 191 heats and dries the coating film 13 by operating the heating unit 180 to form an adhesive layer 11. At this time, the coating liquid supply source 170a may supply the coating liquid 12 so that the coating film 13 becomes a single layer, or it may supply the coating liquid 12 so that the coating film 13 becomes a laminate of multiple layers. Once a coating film 13 of the desired thickness has been formed over the entire circumference of the conveyor belt 111, the control unit 191 stops the operation of the coating liquid supply unit 170.

[0136] Furthermore, the conveyor belt 111 rotates multiple times from the time the heating unit 180 starts heating the coating 13 until it finishes. This allows the coating 13 to dry thoroughly. However, if the coating 13 is sufficiently dry, the conveyor belt 111 may only need to rotate once.

[0137] When the control unit 191 determines that the coating film 13 has dried sufficiently and the adhesive layer 11 has formed, it notifies the user by displaying a message on the operation unit 197, stops the operation of the heating unit 180 and the drive unit 112, and allows the user to select the second mode on the operation unit 197. The control unit 191 may also determine that an adhesive layer 11 with appropriate properties (moisture content, thickness, viscosity, etc.) has been formed when it recognizes, based on its built-in clock, that a predetermined time has elapsed since the start of the first mode. Alternatively, the control unit 191 may determine that an adhesive layer 11 with appropriate properties has been formed when the conveyor belt 111 has been rotated a predetermined number of times since the start of the first mode.

[0138] Furthermore, the printing apparatus may be equipped with an adhesive layer detection unit capable of detecting the properties of the coating film (moisture content, thickness, viscosity, etc.), and the control unit may have a determination unit that determines whether or not an adhesive layer with appropriate properties has been formed based on the detection results of the adhesive layer detection unit. Specifically, for example, the printing apparatus may be equipped with a moisture content detection unit capable of detecting the moisture content of the coating film as the adhesive layer detection unit, and the determination unit may determine that an adhesive layer 11 with appropriate properties has been formed when the detected moisture content of the coating film falls below a predetermined threshold (upper limit). Examples of moisture content detection units include an infrared moisture meter, an electrical resistance meter, a capacitance meter, etc. Also, for example, the printing apparatus may be equipped with a monitor unit such as a camera that images the coating film as the adhesive layer detection unit, and the determination unit may recognize the properties of the adhesive layer based on the image captured by the monitor unit and determine whether or not an adhesive layer with appropriate properties has been formed.

[0139] Next, the user operates the control unit 197 to select the second mode. The control unit 191 activates the blade 170b's moving mechanism, pre-moving the blade 170b above the transport device 110.

[0140] This enables the second step S2, which involves printing onto the recording medium W. Specifically, as shown in Figure 1, the control unit 191 rotates the main roller 112a in the first direction a1 by operating the drive unit 112 of the transport device 110, causing the transport belt 111 to rotate in a counterclockwise direction in Figure 1, while simultaneously heating the adhesive layer 11 obtained in the first step S1 by operating the heating unit 180. This heating increases the adhesive strength of the adhesive layer 11, resulting in good retention of the recording medium W.

[0141] Furthermore, the control unit 191 operates the unwinding device 120 to unwind the unprinted recording medium W from the unwinding roller 121. The recording medium W unwound by the unwinding device 120 adheres to the heated adhesive layer 11 at the position of the tensioner 113, is held by the transport belt 111 which is moving in a circulating rotation, and is transported downstream in the transport direction. At the same time, the control unit 191 operates the printing unit 140 to print a predetermined image pattern on the recording medium W held by the transport belt 111. In this way, by the recording medium W adhering to the adhesive layer 11 with sufficiently increased adhesive strength, the transport belt 111 can transport the recording medium W stably and properly. Therefore, the printing device 100 can prevent printing defects such as misalignment caused by poor holding or poor transport of the recording medium W, and can print a proper and high-quality image on the recording medium W.

[0142] The printed recording medium W separates from the adhesive layer 11 and the conveyor belt 111 at the position of the tensioner 114. The control unit 191 operates the ink drying unit 150 to dry the ink adhering to the printed recording medium W, and operates the winding device 130 to wind up the ink-dried recording medium W using the winding roller 131.

[0143] The control unit 191 may clean the adhesive layer 11 after the recording medium W has peeled off by operating the cleaning unit 160. The adhesive layer 11 has cooled down by the time it reaches the cleaning unit 160. Therefore, damage to the adhesive layer 11 by the cleaning unit 160 can be suppressed, and the adhesive layer 11 can be reused in good condition.

[0144] As explained above, the rotation direction of the conveyor belt 111 in the second mode is opposite to the rotation direction of the conveyor belt 111 in the first mode. Therefore, it becomes easier to adjust both the timing from when the coating liquid 12 supplied onto the conveyor belt 111 in the first mode is heated by the heating unit 180, and the timing from when the recording medium W adheres to the adhesive layer 11 heated by the heating unit 180 in the second mode.

[0145] Furthermore, the heating unit 180 is positioned below the conveyor belt 111, and in the second mode, along the rotational direction of the conveyor belt 111, the position where the adhesive layer 11 is heated by the heating unit 180, the position where the unwound recording medium W begins to adhere to the adhesive layer 11, the position where the printing unit 140 prints on the recording medium W (printing area 144), and the position where the coating film 13 is formed are arranged in this order. Therefore, in the second mode, the time from when the heating unit 180 heats the adhesive layer 11 until the recording medium W adheres to the adhesive layer 11 can be made relatively short. As a result, the heated adhesive layer 11 can adhere to and hold the recording medium W before it cools down, that is, before its adhesive strength decreases. On the other hand, in the first mode, the coating film 13 after passing through the blade 170b can be allowed to air dry to some extent before reaching the heating unit 180. This natural drying process prevents dripping from the coating 13 and deformation of the coating 13 due to gravity before the coating 13 reaches the heating section 180 located below the conveyor belt 111.

[0146] The control unit 191 may notify (display) the operation unit 197 or the like, for example, when the portion of the recording medium W that has been printed has been wound onto the winding roller 131 by the operation of the winding device 130, according to the winding length or elapsed time.

[0147] The heating conditions for the coating film 13 (water-based adhesive) in the first mode and the heating conditions for the adhesive layer 11 in the second mode may be the same or different, but for the reasons described below, it is preferable that they be different. In this specification, "heating conditions" include the heating temperature of the coating film 13 and the adhesive layer 11, and the heating time for heating the coating film 13 and the adhesive layer 11.

[0148] The heating conditions are preferably set such that the total amount of thermal energy H1 applied to the coating film 13 per unit area in the first mode is greater than the total amount of thermal energy H2 applied to the adhesive layer 11 per unit area in the second mode. The thermal energy ratio H1 / H2 is not particularly limited, but is preferably 1.2 or more and 100 or less, and more preferably 10.0 or more and 50 or less. In order to satisfy these heating conditions, in this embodiment, the heating temperature by the heating unit 180 is the same in the first mode and the second mode, but the heating time is different.

[0149] The heating temperature can be, for example, the ambient temperature between the coating film 13 or adhesive layer 11 and the heating section 180, and is adjusted by the amount of power (wattage) supplied to the heat source 182. In the first and second modes, the heating temperature is not particularly limited, but is preferably 30°C to 80°C, more preferably 30°C to 70°C, and even more preferably 35°C to 60°C, respectively.

[0150] The heating time corresponds to the total time that the coating 13 or adhesive layer 11 per unit area passes directly over the heat dissipation area of ​​the heating unit 180. Therefore, the heating time is determined by the length of the heat dissipation area of ​​the heating unit 180 along the y-axis, the rotational speed of the conveyor belt 111, and the number of times the coating 13 or adhesive layer 11 per unit area passes over the heating unit 180.

[0151] Here, the "heat dissipation region" refers to the region in the heating unit 180 that dissipates heat towards the conveyor belt 111. In this embodiment, the radiating plate 181 and the heat source 182 correspond to the heat dissipation region. In this embodiment, the length of the radiating plate 181 and the heat source 182 along the y-axis is constant regardless of whether it is the first mode or the second mode. However, the length of the heat dissipation region along the y-axis can be changed according to each mode, and the heating time can be adjusted by changing the length of the heat dissipation region along the y-axis according to the mode. For example, a configuration in which a radiating plate and a heat source are set as one unit, multiple such units are arranged along the y-axis, and the number of heat sources supplied with power is changed according to the mode.

[0152] In this embodiment, the rotational speed V1 of the conveyor belt 111 in the first mode (clockwise in Figure 2) and the rotational speed V2 of the conveyor belt 111 in the second mode (counterclockwise in Figure 1) are made different, thereby creating a difference between the total amount of thermal energy H1 and the total amount of thermal energy H2. In particular, while the heating temperature of the heating unit 180 is the same in both the first and second modes, the rotational speed V1 of the conveyor belt 111 in the first mode is made slower than the rotational speed V2 of the conveyor belt 111 in the second mode. As a result, in the first mode in which the adhesive layer 11 is formed, the coating film 13 is sufficiently dried, and an adhesive layer 11 with good adhesive strength and durability can be formed. In addition, the coating film 13 on the conveyor belt 111 can be allowed to air dry to some extent before it reaches the heating unit 180 located below the conveyor belt 111. Therefore, as mentioned above, dripping from the coating film 13 and deformation of the coating film 13 due to gravity can be suppressed.

[0153] On the other hand, in the frequently used second mode, the conveyor belt 111 is rotated at a relatively fast rotation speed V2, which rapidly increases the adhesive strength of the adhesive layer 11 and allows for rapid printing on the recording medium W. The adhesive layer 11 achieves sufficiently high adhesive strength, i.e., high holding power of the recording medium W, through heating. Therefore, even when the recording medium W is conveyed at a relatively fast speed, good print quality can be obtained without printing defects such as misalignment caused by poor holding or poor conveying.

[0154] The rotational speed ratio V1 / V2 is not particularly limited, but is preferably 0.05 or more and 0.9 or less, more preferably 0.07 or more and 0.7 or less, and even more preferably 0.1 or more and 0.5 or less. By setting the rotational speed ratio V1 / V2 within the above range, in the first mode, an adhesive layer 11 with good adhesive strength and durability can be easily and quickly formed. On the other hand, in the second mode, which is used frequently, the adhesive strength of the adhesive layer 11 can be quickly increased while printing quickly on the recording medium W with good print quality. In particular, by setting the rotational speed ratio V1 / V2 to or below the above upper limit, the time required for drying the coating film 13 can be reduced while ensuring sufficient transport speed of the transport belt 111 in the first mode.

[0155] In the first mode, the rotational speed V1 of the conveyor belt 111 depends on the moisture content and heating temperature of the coating film 13, but is preferably, for example, 0.1 m / min or more and 10 m / min or less, more preferably 0.5 m / min or more and 5 m / min or less, and even more preferably 1 m / min or more and 3 m / min or less. In the second mode, the rotational speed V2 of the conveyor belt 111 depends on the heating temperature, but is preferably, for example, 2 m / min or more and 30 m / min or less, more preferably 5 m / min or more and 20 m / min or less, and even more preferably 8 m / min or more and 12 m / min or less.

[0156] The number of times the coating film 13 per unit area passes over the heating unit 180 is the number of times N1 the conveyor belt 111 rotates in a circular motion from the time the heating unit 180 starts heating the coating film 13 until it finishes heating, and in this embodiment, this is multiple times. The number of times the adhesive layer 11 per unit area passes over the heating unit 180 is the number of times N2 the conveyor belt 111 rotates in a circular motion from the time the heating unit 180 starts heating the adhesive layer 11 until the recording medium W adheres to it. In this embodiment, since the conveyor belt 111 holds the unwound recording medium W while heating the adhesive layer 11 on the rotating conveyor belt 111, the number of times N2 the conveyor belt 111 rotates in a circular motion from the time the heating unit 180 starts heating the adhesive layer 11 until the recording medium W adheres to it is 1 time.

[0157] Thus, in this embodiment, the number of rotations N1 of the conveyor belt 111 in the first mode is greater than the number of rotations N2 of the conveyor belt 111 in the second mode. Therefore, in the first mode, when the adhesive layer 11 is formed, the coating film 13 can be sufficiently dried, and an adhesive layer 11 with good adhesive strength and durability can be formed. On the other hand, in the second mode, which is used frequently, the adhesive strength of the adhesive layer 11 can be rapidly increased while printing can be done quickly on the recording medium W.

[0158] In the first mode, the number of rotations N1 of the conveyor belt 111 depends on the moisture content of the undried coating 13, the heating temperature, and the rotation speed V1, but is preferably between 1 and 60 times, more preferably between 10 and 50 times, and even more preferably between 20 and 40 times.

[0159] The heating conditions are not limited to those described above. For example, the heating temperature may differ between the first mode and the second mode, while the heating time may be the same. Alternatively, both the heating temperature and heating time may differ between the first mode and the second mode. In particular, the heating conditions in each mode, such as the heating temperature, rotation speeds V1, V2, rotation speed ratio V1 / V2, number of rotations N1, N2, total amount of thermal energy H1, H2, and thermal energy ratio H1 / H2, may differ from the values ​​or ranges described above.

[0160] The memory unit 192 stores the operating conditions of each part related to the heating conditions, for example, for each first mode and second mode, and these operating conditions are executed as needed. The operating conditions of each part related to the heating conditions are not particularly limited, but examples include the heating temperature or the set temperature of the heat source 182, the rotation speed V1, V2 or motor 112c, the number of times the conveyor belt 111 circulates N1, N2 or the time the conveyor belt 111 circulates. The control unit 191 can determine the rotation direction of the conveyor belt 111, the rotation speed V1, V2, the number of times N1, N2, etc., based on the detected values ​​(information) detected by the rotation detection unit 115 described above.

[0161] Furthermore, the storage unit 192 may store the total amount of thermal energy H1, H2 or the thermal energy ratio H1 / H2, and the arithmetic processing unit 193 may calculate the heating temperature, rotation speed V1, V2, number of cycles N1, N2, etc. for each mode based on these values. In this case, the numerical values ​​(parameters) related to the heating conditions, such as the heating temperature, rotation speed V1, V2, rotation speed ratio V1 / V2, number of cycles N1, N2, total amount of thermal energy H1, H2, and thermal energy ratio H1 / H2 for each mode, may be stored in the storage unit 192 in advance, or they may be input by the operation unit 197 and stored in the storage unit 192. In addition, these numerical values ​​stored in the storage unit 192 may be rewritable by operation of the operation unit 197. Furthermore, the printing device may be equipped with a thermometer and hygrometer capable of measuring the temperature and humidity of the atmosphere, and the control unit may adjust the heating conditions when heating the coating film according to the temperature and humidity measured by the thermometer and hygrometer. This allows for adjustment of heating conditions, such as increasing the heating temperature, when the temperature and humidity of the atmosphere are high and humid. As a result, an adhesive layer with good adhesion and durability can be formed stably and efficiently, regardless of the temperature and humidity of the printing apparatus.

[0162] As described above, the printing apparatus 100 is a printing apparatus that prints on a recording medium W while holding the recording medium W with an adhesive layer 11 formed of an aqueous adhesive containing water and resin. The printing apparatus 100 includes an endless conveyor belt 111 for transporting the recording medium W, a drive unit 112 for circulating rotation of the conveyor belt 111, a heating unit 180 installed around the conveyor belt 111, a printing unit 140 for printing on the recording medium W being transported by the conveyor belt 111, and a control unit 191 for controlling the operation of the drive unit 112, the heating unit 180, and the printing unit 140. The control unit 191 can select between a first mode and a second mode. In the first mode, when the conveyor belt 111 is not holding the recording medium W and is circulating rotation, the heating unit 180 heats the aqueous adhesive applied to the conveyor belt 111 to form an adhesive layer 11 on the conveyor belt 111. In the second mode, with the conveyor belt 111 rotating in a circular motion, the heating unit 180 heats the adhesive layer 11, and the printing unit 140 prints onto the recording medium W held by the conveyor belt 111.

[0163] Thus, by using an aqueous adhesive, the workload on the user can be reduced compared to using an adhesive that uses an organic solvent. Furthermore, since the heating unit 180 heats the aqueous adhesive applied to the conveyor belt 111 to promote drying, the time required to form the adhesive layer 11 can be reduced compared to natural drying. The heating unit 180 is used for both drying the aqueous adhesive applied to the conveyor belt 111 and heating the adhesive layer 11 to increase its adhesive strength. Therefore, the structure of the printing apparatus 100 can be simplified. In other words, a printing apparatus 100 can be realized with a simple structure that reduces the time required to form the adhesive layer 11. Moreover, since the heating unit 180 heats the aqueous adhesive applied to the conveyor belt 111 to dry it, the drying conditions of the aqueous adhesive can be stabilized. As a result, an adhesive layer 11 with good adhesive strength and durability can be stably formed regardless of the temperature and humidity of the atmosphere inside the printing apparatus 100. As a result, the printing device 100 can perform printing while properly transporting the recording medium W in a stable manner, thereby suppressing printing defects such as misalignment caused by poor holding or transport. This improves print quality.

[0164] Furthermore, the heating conditions for the aqueous adhesive in the first mode are different from those for the adhesive layer 11 in the second mode. Therefore, even though the heating unit 180 is used for both the first and second modes, it is possible to set heating conditions suitable for each mode.

[0165] Furthermore, the rotation speed of the conveyor belt 111 in the first mode is slower than the rotation speed of the conveyor belt 111 in the second mode. Therefore, in the first mode, which forms the adhesive layer 11, the coating film 13 can be dried at an appropriate drying rate, that is, it can be dried sufficiently to the desired extent, and an adhesive layer 11 with good adhesive strength and durability can be formed. On the other hand, in the second mode, which prints on a frequently used recording medium W, the adhesive strength of the adhesive layer 11 can be increased quickly while printing can be done quickly.

[0166] Furthermore, the rotation direction of the conveyor belt 111 in the first mode is opposite to the rotation direction of the conveyor belt 111 in the second mode. This makes it easier to adjust both the timing from when the coating liquid 12 supplied onto the conveyor belt 111 in the first mode is heated by the heating unit 180, and the timing from when the recording medium W adheres to the adhesive layer 11 heated by the heating unit 180 in the second mode.

[0167] Furthermore, the heating unit 180 is not in contact with the adhesive layer forming surface 111s of the conveyor belt 111. Therefore, damage to the adhesive layer 11 and coating 13 on the adhesive layer forming surface 111s, as well as the adhesion of dirt, can be suppressed.

[0168] Furthermore, the printing apparatus 100 is further equipped with a coating liquid supply unit 170 that applies a water-based adhesive coating liquid 12 to the adhesive layer forming surface 111s of the conveyor belt 111. This allows the printing apparatus 100 to supply the coating liquid 12 using its own coating liquid supply unit 170 and apply it to the adhesive layer forming surface 111s of the conveyor belt 111. As a result, the printing apparatus 100 can easily and stably form the coating film 13 and the adhesive layer 11, and can form a uniform and homogeneous adhesive layer 11 without unevenness in film thickness or properties. Consequently, the printing apparatus 100 can print while properly conveying the recording medium W in a stable and reliable manner, thereby improving print quality.

[0169] Furthermore, the resin includes a (meth)acrylic resin. By including such a resin in the adhesive layer 11, the adhesive strength, stability, and durability of the adhesive layer 11 can be improved. Moreover, such resins are highly versatile, readily available, and easy to handle. By selecting the chemical composition, molecular weight, glass transition temperature, etc., a wide range of settings are possible regarding the adhesive strength and its durability. Therefore, it is possible to easily design an adhesive layer 11 with desired performance and characteristics according to conditions such as the type and thickness of the recording medium W and printing conditions such as printing speed.

[0170] Furthermore, the control method for the printing apparatus 100 comprises an endless conveyor belt 111 for conveying a recording medium W, a drive unit 112 for circulating rotation of the conveyor belt 111, a heating unit 180 installed around the conveyor belt 111, and a printing unit 140 for printing on the recording medium W being conveyed by the conveyor belt 111. The control method for the printing apparatus 100 includes a first step S1 in which, while the conveyor belt 111 is not holding the recording medium W and is circulating rotation, the heating unit 180 heats the aqueous adhesive applied to the conveyor belt 111 to form an adhesive layer 11 on the conveyor belt 111, and a second step S2 in which, while the conveyor belt 111 is circulating rotation, the heating unit 180 heats the adhesive layer 11 and the printing unit 140 prints on the recording medium W held by the conveyor belt 111.

[0171] Thus, by using a water-based adhesive, the workload on the user can be reduced compared to using an adhesive that uses an organic solvent. Also, similar to the effect of the printing apparatus 100 described above, the time required to form the adhesive layer 11 can be reduced with a printing apparatus 100 that has a simple structure. Furthermore, an adhesive layer 11 with good adhesive strength and durability can be stably formed regardless of the temperature and humidity of the atmosphere inside the printing apparatus 100. As a result, the printing apparatus 100 can perform printing while properly transporting the recording medium W in the second step S2 while stably and reliably holding it, thereby improving print quality.

[0172] <Second Embodiment> Next, a printing apparatus 200 according to the second embodiment will be described.

[0173] Figure 4 shows the state in which the coating film 13 on the conveyor belt 111 of the printing apparatus 200 according to this embodiment is being heated.

[0174] Note that in Figure 4, the unwinding device 120, the winding device 130, the ink drying unit 150, and the washing unit 160 are omitted from the illustration. Also, in Figure 4, the tensioner 114 is located away from the conveyor belt 111, but its illustration is omitted.

[0175] The printing apparatus 200 according to this embodiment differs from the printing apparatus 100 according to the first embodiment in that it is equipped with an auxiliary heating unit 213 instead of the tensioner 113 of the printing apparatus 100 according to the first embodiment. Hereinafter, the differences between the second embodiment and the first embodiment will be mainly described, and descriptions of configurations similar to those of the first embodiment will be omitted as appropriate.

[0176] The auxiliary heating section 213 is roller-shaped. A heat source (heater) is provided inside the auxiliary heating section 213. In other words, the auxiliary heating section 213 is composed of heating rollers. The auxiliary heating section 213 is configured to move in the z-axis direction by a moving mechanism (not shown) and to move toward and away from the conveyor belt 111. Examples of the moving mechanism include those equipped with a drive source such as an air cylinder, an oil cylinder, or a solenoid. The heat source and the moving mechanism in the auxiliary heating section 213 are electrically connected to the control unit 191, and their operation is controlled by the control unit 191.

[0177] In the second mode, similar to the tensioner 113 in the first embodiment, the outer circumferential surface of the roller of the auxiliary heating unit 213 is positioned to contact the recording medium W, and the auxiliary heating unit 213 rotates together with the transport of the recording medium W. As a result, the auxiliary heating unit 213 performs the same function as the tensioner 113 shown in Figure 1. That is, in the second mode, the auxiliary heating unit 213 sandwiches the recording medium W together with the transport belt 111 between itself and the main roller 112a, applying appropriate tension to the recording medium W. The auxiliary heating unit 213 may rotate as the main unit or as the driven unit. In this case, power may be supplied to the heat source of the auxiliary heating unit 213, or the heat source inside the auxiliary heating unit 213 may be inactive. When power is supplied to the heat source of the auxiliary heating unit 213, the auxiliary heating unit 213 can heat the adhesive layer 11 via the recording medium W. As a result, the adhesive strength of the adhesive layer 11 can be further increased.

[0178] During the first mode, the auxiliary heating unit 213 is moved from a standby position separated from the conveyor belt 111 to a position where the outer surface of the rollers of the auxiliary heating unit 213 comes into contact with the coating film 13. Power is supplied to the heat source inside the auxiliary heating unit 213, and the auxiliary heating unit 213 auxiliaryly heats and dries the coating film 13. At this time, the auxiliary heating unit 213 may rotate counterclockwise in Figure 4 along with the conveyance of the coating film 13.

[0179] Thus, the auxiliary heating unit 213 is used for both assisting (accelerating) the drying of the coating film 13 by auxiliaryly or preliminarily heating the coating film 13 in the first mode, and for further optimizing the transport of the recording medium W by applying tension to the recording medium W in the second mode. Therefore, the printing apparatus 200 exhibits the same effects as described in the printing apparatus 100 according to the first embodiment, while simplifying the configuration of the printing apparatus 200 and further reducing the time required to form the adhesive layer 11, while forming an adhesive layer 11 with good adhesive strength and durability.

[0180] Next, the control method for the printing device 200 will be explained. In the first mode, the control unit 191, similar to the first embodiment, rotates the conveyor belt 111 in a circulating manner by operating the drive unit 112 of the conveying device 110, while supplying the aqueous adhesive coating liquid 12 onto the conveyor belt 111 by operating the coating liquid supply source 170a. The coating liquid 12 on the conveyor belt 111 is leveled by the blade 170b, resulting in a coating film 13 with a generally uniform thickness. The control unit 191 then operates the heating unit 180 to heat the coating film 13. Before the supply of the coating liquid 12 by the coating liquid supply source 170a is started, the control unit 191 moves the auxiliary heating unit 213 to a standby position away from the coating film 13 on the conveyor belt 111.

[0181] Next, the control unit 191 stops the supply of coating liquid 12 by the coating liquid supply unit 170. At this time, the drive unit 112 continues to circulate the conveyor belt 111, and the heating unit 180 continues to heat the coating film 13.

[0182] Next, as shown in Figure 4, the control unit 191 activates the movement mechanism of the auxiliary heating unit 213, bringing the auxiliary heating unit 213 into contact with the coating film 13 on the conveyor belt 111, and heating the coating film 13 through the operation of the heating unit 180 and the auxiliary heating unit 213. By using the auxiliary heating unit 213 in addition to the heating unit 180 for auxiliary heating, the coating film 13 can be dried more quickly. Furthermore, since the auxiliary heating unit 213 heats the coating film 13 in contact with it, the coating film 13 can be dried efficiently and thoroughly. As a result, an adhesive layer 11 with good adhesive strength and durability can be formed.

[0183] The timing for bringing the auxiliary heating unit 213 into contact with the coating film 13 on the conveyor belt 111 is not particularly limited, but for example, it is set to a timing when the coating film 13 has dried to some extent by the heating unit 180, and the aqueous adhesive (aqueous adhesive composition) constituting the coating film 13 does not adhere to the auxiliary heating unit 213 even when the auxiliary heating unit 213 is brought into contact with the coating film 13.

[0184] At the timing when the auxiliary heating unit 213 is brought into contact with the coating film 13 on the conveyor belt 111, the moisture content of the coating film 13 is preferably 0.1% by weight or more and 10% by weight or less, more preferably 0.5% by weight or more and 5% by weight or less, and even more preferably 1% by weight or more and 3% by weight or less. According to the inventors' studies, it has been found that when the water in the coating film 13 is evaporated until the moisture content of the coating film 13 is below the above upper limit, the adhesion of the aqueous adhesive composition constituting the coating film 13 to the auxiliary heating unit 213 can be suitably suppressed. Furthermore, by bringing the auxiliary heating unit 213 into contact with the coating film 13 when the moisture content of the coating film 13 is above the above lower limit, the coating film 13 can be dried relatively quickly.

[0185] In the second mode, the control unit 191 rotates the conveyor belt 111 in a circulating manner by operating the drive unit 112 of the conveying device 110, while heating the adhesive layer 11 with the heating unit 180. This increases the adhesive strength of the adhesive layer 11, improving the holding ability of the recording medium W. The control unit 191 also operates the unwinding device 120 to unwind the recording medium W from the unwinding roller 121. At this time, the control unit 191 operates the movement mechanism of the auxiliary heating unit 213 to bring the outer circumferential surface of the roller of the auxiliary heating unit 213 into contact with the recording medium W on the conveyor belt 111, applying appropriate tension to the recording medium W. The recording medium W unwound by the unwinding device 120 comes into contact with the outer circumferential surface of the roller of the auxiliary heating unit 213 and adheres to the adhesive layer 11 on the conveyor belt 111. As a result, the conveyor belt 111 holds the recording medium W and conveys it downstream in the conveying direction.

[0186] Simultaneously, the control unit 191 operates the printing unit 140 to print as the recording medium W held by the conveyor belt 111 passes through the printing area 144. The control unit 191 operates the ink drying unit 150 to dry the ink adhering to the printed recording medium W, and operates the winding device 130 to wind the printed recording medium W onto the winding roller 131. In this way, the auxiliary heating unit 213 applies appropriate tension to the recording medium W, reducing the occurrence of wrinkles, sagging, etc., during the conveyance of the recording medium W. As a result, when printing is performed on the recording medium W, the printing is proper and of high quality.

[0187] As described above, the printing apparatus 200 is further equipped with an auxiliary heating unit 213. In the first mode, the auxiliary heating unit 213 contacts the aqueous adhesive applied to the conveyor belt 111 and heats the aqueous adhesive together with the heating unit 180. As a result, the aqueous adhesive can be dried quickly and thoroughly. Consequently, an adhesive layer 11 with good adhesive strength and durability can be formed quickly.

[0188] The printing apparatus 200 may be equipped with an auxiliary heating unit 213 instead of the tensioner 114 of the printing apparatus 100 according to the first embodiment. Alternatively, both tensioners 113 and 114 may be replaced with the auxiliary heating unit 213. Furthermore, the user may be able to select whether or not to use the auxiliary heating unit 213 in the second mode via the operation unit 197.

[0189] Furthermore, the configuration, position, function, and usage method of the auxiliary heating unit are not limited to those described above. For example, the movement mechanism of the auxiliary heating unit may be such that the auxiliary heating unit can move along the transport direction of the recording medium. Also, the auxiliary heating unit is not limited to a roller shape.

[0190] Although the printed apparatus and control method of the printed apparatus of the present invention have been described above in the illustrated embodiments, the present invention is not limited to these embodiments. Furthermore, each part and each process of the printed apparatus and the control method of the printed apparatus can be replaced with any structure or process that can perform similar functions. In addition, any structure or process may be added. [Explanation of Symbols]

[0191] 11...Adhesive layer, 12...Coating liquid, 13...Coating film, 100...Printing device, 110...Conveying device, 111...Conveyor belt, 111s...Adhesive layer forming surface, 112...Drive unit, 112a...Driven roller, 112b...Driven roller, 112c...Motor, 113...Tensioner, 114...Tensioner, 115...Rotation detection unit, 120...Unwinding device, 121...Unwinding roller, 122...Motor, 123...Tensioner, 130...Winding device, 131...Winding roller, 132...Motor, 133...Tensioner, 134...Tensioner, 135...Tensioner, 140...Printing unit, 141...Inkjet head, 142...Carrier 144…Printing area, 150…Ink drying section, 151…Chamber, 152…Coil, 160…Cleaning section, 161…Storage tank, 162…Cleaning brush, 170…Coating liquid supply section, 170a…Coating liquid supply source, 170b…Blade, 171…Storage section, 172…Liquid supply pipe, 173…Liquid supply pump, 180…Heating section, 181…Radiating plate, 182…Heat source, 183…Frame, 191…Control unit, 192…Storage unit, 193…Calculation processing unit, 194…Communication unit, 197…Operation unit, 200…Printing device, 213…Auxiliary heating section, G…Distance, S1…First process, S2…Second process, W…Recording medium, a1…First direction, a2…Second direction

Claims

1. A printing apparatus for printing on a recording medium while holding the recording medium with an adhesive layer formed of an aqueous adhesive containing water and resin, An endless conveying belt for transporting the recording medium, A drive unit that rotates the aforementioned conveyor belt in a circulating manner, A heating unit installed around the aforementioned conveyor belt, A printing unit that prints on the recording medium being transported by the aforementioned conveyor belt, A control unit that controls the operation of the drive unit, the heating unit, and the printing unit, Equipped with, The control unit, In a first mode, the conveyor belt is not holding the recording medium and is rotating in a circulating manner, and the heating unit heats the aqueous adhesive applied to the conveyor belt to form the adhesive layer on the conveyor belt. In a second mode, the conveyor belt is rotating in a circulating manner, the heating unit heats the adhesive layer, and the printing unit prints on the recording medium held by the conveyor belt. A printing apparatus characterized by the ability to select [a specific option].

2. The printing apparatus according to claim 1, wherein the heating conditions for the aqueous adhesive in the first mode are different from the heating conditions for the adhesive layer in the second mode.

3. The printing apparatus according to claim 2, wherein the rotational speed of the conveyor belt in the first mode is slower than the rotational speed of the conveyor belt in the second mode.

4. The printing apparatus according to any one of claims 1 to 3, wherein the direction of rotation of the conveyor belt in the first mode is opposite to the direction of rotation of the conveyor belt in the second mode.

5. The printing apparatus according to any one of claims 1 to 3, wherein the heating section is not in contact with the adhesive layer forming surface of the conveyor belt.

6. It is further equipped with an auxiliary heating section, The printing apparatus according to claim 5, wherein the auxiliary heating unit, in the first mode, comes into contact with the aqueous adhesive applied to the conveyor belt and heats the aqueous adhesive together with the heating unit.

7. The printing apparatus according to any one of claims 1 to 3, further comprising a coating liquid supply unit for applying the aqueous adhesive coating liquid to the adhesive layer forming surface of the conveyor belt.

8. The printing apparatus according to any one of claims 1 to 3, wherein the resin comprises a (meth)acrylic resin.

9. An endless conveyor belt for transporting recording media, A drive unit that rotates the aforementioned conveyor belt in a circulating manner, A heating unit installed around the aforementioned conveyor belt, A printing unit that prints on the recording medium being transported by the aforementioned conveyor belt, A control method for a printing apparatus comprising: The first step involves heating the aqueous adhesive applied to the conveyor belt by the heating unit while the conveyor belt is not holding the recording medium and is rotating in a circulating manner, thereby forming an adhesive layer on the conveyor belt. A second step involves heating the adhesive layer with the heating unit while the conveyor belt is rotating in a circulating manner, and printing on the recording medium held by the conveyor belt with the printing unit. A method for controlling a printing apparatus, characterized by having the following features.

Images