JP2024048607A - Inkjet printing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printing device and method which prevent cracking of a printing image, and secure image quality and adhesion, when performing printing treatment on a metallic base material having inferior water absorption property using aqueous ink.

SOLUTION: An inkjet printing device includes: a head unit for discharging aqueous ink to non-absorptive metallic base materials 15a and 15b coated with a pretreatment agent for aggregating aqueous ink, and performing printing treatment thereon; a temperature sensor 27 for detecting temperatures of printing surfaces of the base materials 15a and 15b; and a heating unit 5 capable of heating the base materials at partially different temperatures in the printing treatment, on the basis of the temperatures detected by the temperature sensor 27.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an inkjet printing device and method that ejects ink onto a non-absorbent metal substrate to perform a printing process.

In recent years, inkjet printing devices have been proposed that eject ink onto a variety of substrates, including not only paper and film but also building materials and decorative panels, to perform printing processes.

For example, when printing on a metal substrate, which has poor water absorption properties, using an inkjet printing device that uses water-based ink, a pretreatment agent that causes an agglomeration reaction with the ink must be applied to the substrate in order to ensure image quality.

JP 2017-109411 A JP 2017-165005 A JP 2008-3032358 A

Here, the pretreatment agent needs to contain a binder resin to bond the pretreatment agent to the substrate. In addition, in order to improve compatibility with water-based ink and ensure image quality, it is preferable that the pretreatment agent is hydrophilic.

On the other hand, water-based inks contain colorants, water, solvents, activators, binder resins, etc. Therefore, if the substrate has poor water absorption, the ink components ejected onto the substrate during printing undergo an aggregation reaction to form an image, and at the same time, the moisture contained in the ink remains for a while on the pretreatment layer formed by the pretreatment agent.

As a result, the pretreatment layer gradually softens due to the moisture in the retained ink, and the ink layer that forms the image in the correct location through an aggregation reaction moves along with the pretreatment layer. As a result, the printed image appears cracked. The more retained moisture there is in the areas with higher print density, the more noticeable the cracks become.

To prevent such cracking of printed images, it is conceivable to use a pretreatment agent that is not easily softened by the moisture contained in the water-based ink, but weakening the hydrophilicity makes the ink more likely to repel, making it difficult to form accurate images using only the aggregation reaction between the pretreatment agent and the ink.

Another option is to reduce the moisture content in the ink, but if the ink solids content becomes higher than necessary, it will be difficult to eject ink from the inkjet head accurately and stably.

Another method that can be considered is to evaporate the water contained in the ink by heating, but in the case of metal-based substrates, the thermal conductivity may differ locally, and differences in surface temperature may cause the printed dot diameter to differ locally, resulting in uneven printing and density, leading to reduced image quality.

Patent Document 1 proposes an inkjet recording method that can prevent uneven density and cracks in the printed image and form high-definition images when performing solid printing with a large amount of ink applied onto a film substrate.

However, to form a coating layer containing 60% or more by mass of water-based latex resin, as in the method described in Patent Document 1, a highly viscous coating liquid must be handled, making it difficult to apply the coating uniformly to a metal substrate. In addition, film substrates have a different surface condition than metal substrates. Polypropylene in particular has surface treatments that enable printing, antistatic treatments, voids caused by the manufacturing method, and cushioning properties in the material. Metals do not have these characteristics, and the technology described in Patent Document 1, which is based on the premise of treatment on a film substrate, is insufficient.

Patent Document 2 also discloses an inkjet printing device that performs printing processing with aqueous ink on non-absorbent or low-absorbent substrates, but does not propose any method for solving the above-mentioned cracking of printed images.

Patent Document 3 also proposes a method of heating and drying a resin substrate or a non-absorbent inorganic substrate before or during transportation when printing with a non-aqueous ink containing a highly volatile organic solvent on the substrate. However, Patent Document 3 does not take into consideration the cracking of the printed image described above when using aqueous ink.

The present invention aims to provide an inkjet printing device and method that can prevent cracking of the printed image and ensure image quality and adhesion when performing printing processing using aqueous ink on metal-based substrates that have poor water absorption.

The inkjet printing device of the present invention includes a head unit that performs a printing process by ejecting aqueous ink onto a non-absorbent metal substrate coated with a pretreatment agent that causes the aqueous ink to aggregate, a temperature detection unit that detects the temperature of the substrate's printing surface, and a heating unit that can heat the substrate at different temperatures in different parts of the substrate during the printing process based on the temperature detected by the temperature detection unit so that the temperature of the substrate's printing surface becomes uniform.

The inkjet printing device of the present invention detects the temperature of the printing surface of the substrate, and based on the detected temperature, heats the substrate at different temperatures during printing, thereby preventing cracks in the printed image and ensuring image quality and adhesion.

FIG. 1 is an external perspective view showing a schematic configuration of an embodiment of an inkjet printing apparatus according to the present invention; A diagram showing the internal structure of the shuttle unit. Top view of the flatbed unit, shuttle unit, and heating unit Flatbed unit, shuttle unit and heating unit viewed from the left FIG. 1 is a diagram showing a schematic configuration of an airflow generating unit; FIG. 2 is a block diagram showing the configuration of the controlled object of the inkjet printing apparatus shown in FIG. 1 is a flowchart illustrating a process flow using the inkjet printing apparatus shown in FIG.

An embodiment of an inkjet printing device of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram of an inkjet printing device 1 of this embodiment. In the following description of the embodiment, the up, down, left, right, front, and rear directions indicated by arrows in FIG. 1 are the up, down, left, right, front, and rear directions of the inkjet printing device 1 of this embodiment.

As shown in FIG. 1, the inkjet printing device 1 of this embodiment includes a shuttle base unit 2, a flatbed unit 3, a shuttle unit 4, a heating unit 5, and a thermographic camera 6 (not shown in FIG. 1).

The shuttle base unit 2 supports the shuttle unit 4 and the heating unit 5, and moves the shuttle unit 4 and the heating unit 5 in the front-back direction (sub-scanning direction). Specifically, the shuttle base unit 2 includes a stand 11, sub-scanning drive guides 13A and 13B, and a sub-scanning drive motor 12 (see FIG. 6).

The stand 11 is formed in a rectangular frame shape and supports the shuttle unit 4 and the heating unit 5. Sub-scanning drive guides 13A and 13B extending in the front-rear direction are formed on the left and right frames of the stand 11. The sub-scanning drive guides 13A and 13B guide the shuttle unit 4 and the heating unit 5 to move in the front-rear direction. The sub-scanning drive motor 12 drives the sub-scanning drive guides 13A and 13B to move the shuttle unit 4 and the heating unit 5 in the front-rear direction.

The flatbed unit 3 supports the substrate 15 (see Figure 2).

In this embodiment, a non-absorbent metal-based plate-shaped substrate 15 is used as the substrate 15. Examples of non-absorbent metal-based substrates 15 include a single metal substrate made of metal only, a composite substrate with a flat metal plate surface (printing surface) and a cushioned back surface made of fibrous metal, a substrate made of metal and hollow, a substrate whose hollow portion is made of a material other than metal, a substrate whose surface (printing surface) is formed in a flat bridge shape with curvature and only a part of its back surface is in contact with the flatbed unit 3, and a substrate that combines the various substrates described above. These non-absorbent metal-based plate-shaped substrates 15 are used for building materials, clock dials, doors, etc.

To determine non-absorbency, tilt the substrate 15 at 45°, drop two drops of water using a dropper with a total length of 135 mm and inner and outer diameters of 1.7 mm and 3.1 mm, and measure the distance traveled by the drop after two seconds. A distance of 15 cm/2s or more is defined as non-absorbency.

Also, as the non-absorbent metal plate-shaped substrate 15, a substrate that has been plated with brass can be used. Examples of plating include silver plating, nickel plating, and chrome plating. The difference in the plating process results in different thermal conductivity and different temperature rises due to heating.

In addition, the number of substrates 15 placed on the flatbed unit 3 is not limited to one, but multiple substrates can be placed and printed simultaneously.

The flatbed unit 3 is disposed in a rectangular recess formed inside the stand portion 11 of the shuttle base unit 2. The flatbed unit 3 has a substrate placement surface 3a, which is a horizontal surface on which the substrate 15 is placed. The flatbed unit 3 has a hydraulic drive mechanism (not shown) and the like, which is configured to adjust the height of the substrate placement surface 3a.

The flatbed unit 3 also includes a heater section 7 (see FIG. 2) that heats the entire substrate placement surface 3a. In this embodiment, a sheet heater having an electric heating wire is used as the heater section 7, but a hot plate may also be used.

The shuttle unit 4 performs a printing process on the substrate 15. Figure 2 shows the schematic configuration of the shuttle unit 4.

As shown in FIG. 2, the shuttle unit 4 includes a housing 21, a main scanning drive guide 22, a main scanning drive motor 23 (see FIG. 6), a head lift guide 24, a head lift motor 25 (see FIG. 6), a head unit 26, and a temperature sensor 27 (not shown in FIG. 2, see FIGS. 3 and 4). In this embodiment, the temperature sensor 27 corresponds to the temperature detection unit of the present invention.

The housing 21 houses the head unit 26 and other components. The housing 21 is formed in a gate shape that straddles the flatbed unit 3 in the left-right direction. The housing 21 is supported by the stand 11 of the shuttle base unit 2 and is configured to be movable along the sub-scanning drive guides 13A and 13B.

The main scanning drive guide 22 guides the head unit 26 to move in the left-right direction (main scanning direction). The main scanning drive guide 22 is formed of a long member that extends in the left-right direction. The head unit 26 moves in the left-right direction by the main scanning drive motor 23.

The head lift guide 24 guides the head unit 26 to move in the vertical direction. The head lift guide 24 is formed from a member that is elongated in the vertical direction. The head lift guide 24 is configured to be movable in the left-right direction along the main scanning drive guide 22 together with the head unit 26. The head unit 26 is raised and lowered in the vertical direction by the head lift motor 25.

The head unit 26 performs printing by ejecting ink onto the substrate 15 while moving left and right along the main scanning drive guide 22 as described above. The head unit 26 has four inkjet heads 31 as shown in FIG. 2.

The four inkjet heads 31 are arranged in parallel in the left-right direction. Each of the four inkjet heads 31 ejects ink of a different color (e.g., cyan, black, magenta, and yellow).

In this embodiment, an aqueous ink is used. The aqueous ink contains a colorant, water, a solvent, an activator, a binder resin, and the like. As the colorant, a pigment is preferable from the viewpoint of light resistance. Water is a dispersion medium for the colorant and the binder resin, and is used to adjust the solid content of the ink. The solvent is used as an anti-drying agent for the nozzles of the inkjet head, and the activator is used as a surface tension adjuster for the ink. The binder resin is used to adhere the colorant to the layer of the pretreatment agent, and undergoes an aggregation reaction with the pretreatment agent.

The heating unit 5 dries the ink on the substrate 15 to which the pretreatment agent has been applied, and heats the printing surface of the substrate 15 during the printing process. Figure 3 is a top view of the flatbed unit 3, two substrates 15a and 15b, the shuttle unit 4, and the heating unit 5, and Figure 4 is a left-side view of the flatbed unit 3, the shuttle unit 4, and the heating unit 5.

The heating unit 5 includes multiple airflow generating units 5a to 5d arranged in the left-right direction. In this embodiment, four airflow generating units 5a to 5d are provided, but any other number may be used as long as one or more substrates 15 placed on the substrate mounting surface 3a can be partially heated at different temperatures.

As shown in Figures 3 and 4, the airflow generating units 5a to 5d generate heated airflows in a direction along the printing surface of the substrate 15 (a direction along the substrate mounting surface 3a). In this embodiment, the airflow generating units 5a to 5d generate airflows that flow from the front side to the rear side.

Figure 5 shows an example of the configuration of airflow generating unit 5a. The other airflow generating units 5b to 5d have a similar configuration. As shown in Figure 5, airflow generating unit 5a includes an exhaust duct 50, a heater 51, and a fan 52.

As it is necessary to replace the air in a relatively closed space, a sirocco fan is preferable as the fan 52, as it has a strong pushing force and can blow air into a small space.

A PTC (Positive Temperature Coefficient) thermistor can be used as the heater 51, which allows for easy temperature control and wiring, and provides rapid temperature rise and stable heat generation characteristics.

In the airflow generating units 5a to 5d, the rotation speed of the fan 52 is controlled to control the volume of hot air, thereby controlling the heating temperature of the substrate 15. The heating temperature of each of the airflow generating units 5a to 5d is controlled independently.

The heating unit 5 is disposed behind the shuttle unit 4 as shown in Figures 3 and 4. The heating unit 5 moves in the same direction as the shuttle unit 4 in synchronization with it.

The temperature of the entire substrate placement surface 3a of the flatbed unit 3 is monitored by the above-mentioned thermographic camera 6 (see FIG. 4). Specifically, a compact thermographic camera 6 is mounted on the top of the shuttle unit 4. The thermographic camera 6 is preferably equipped with an infrared camera and a digital camera function. By simultaneously capturing images with the infrared camera and the digital camera, the temperature of the entire printing surface can be detected in real time, and temperature detection for each area of the heating mechanism (heater section 7 and airflow generating unit 5a) becomes possible. Then, based on the temperature state measured by the thermographic camera 6, the heater section 7 and each airflow generating unit 5a provided under the substrate placement surface 3a are controlled.

For example, when heating two substrates 15a and 15b with different thermal conductivities as shown in FIG. 3, the required surface temperature during printing may not be obtained by controlling the temperature of the heater unit 7 alone. The surface temperature required during printing is a temperature at which the ink ejected from the head unit 26 does not dry out and impair printing stability, and is a temperature at which the pretreatment layer made of the pretreatment agent does not soften due to moisture in the ink.

For example, the airflow generating units 5a and 5b apply the necessary hot air to the substrate 15a, and the airflow generating units 5c and 5d apply the necessary hot air to the substrate 15b, thereby making the surface temperatures of the substrates 15a and 15b uniform and providing the necessary surface temperature. Specifically, the surface temperatures of the substrates 15a and 15b are preferably 50°C or higher, and more preferably 55°C or higher. Note that, although an example of making the surface temperatures of the two substrates 15a and 15b uniform is described here, in the same manner, in the case where the thermal conductivity of one substrate 15 differs in parts, the airflow generating units 5a to 5d apply the necessary hot air to the substrate 15, making the surface temperature of the entire substrate 15 uniform and providing the necessary surface temperature.

In addition, because it takes time to change the temperature of the heater section 7, it is preferable to maintain the temperature of the heater section 7 constant and control the surface temperature of each of the substrates 15a, 15b independently by controlling the temperature of the hot air with the rotation speed of the fan 52 of each of the airflow generating units 5a to 5d.

The surface temperatures of the substrates 15a and 15b immediately before printing are measured by the temperature sensor 27 shown in Figures 3 and 4. As the temperature sensor 27, for example, a non-contact type infrared radiation thermometer can be used.

The temperature sensor 27 is provided on the front side of the head unit 26 and moves left and right together with the head unit 26. This allows the temperature sensor 27 to measure the surface temperature of the next scanning range while the head unit 26 ejects ink into a specified scanning range to perform the printing process.

Figure 6 is a block diagram showing the control system of the inkjet printing device 1 of this embodiment. The inkjet printing device 1 is equipped with a control unit 8 that controls the entire device. The control unit 8 is composed of a computer equipped with a CPU (Central Processing Unit), semiconductor memory, a hard disk, etc. The control unit 8 controls each part shown in Figure 6 by executing a program stored in advance in a storage medium such as the semiconductor memory or the hard disk, and by operating an electric circuit.

Next, the process flow using the inkjet printing device 1 of the above embodiment will be described with reference to the flowchart shown in FIG.

First, a pretreatment agent is applied to the printing surface of the substrate 15 (S10). The pretreatment agent can be applied using a spray, roller, brush, or the like.

Next, the substrate 15 to which the pretreatment agent has been applied is dried (S12). The pretreatment agent is dried at a temperature higher than the heating temperature during the printing process, and is dried in a drying device separate from the inkjet printing device 1. A drying temperature of 100°C or higher is preferable. If the substrate 15 is relatively small, a commercially available thermostatic bath can be used, and a batch-type electric dryer can be used. If the substrate is large, a conveyor-type continuous dryer can be used, and a dryer using a hot air drying method can be used.

Then, the substrate 15 on which the pretreatment agent has been dried is placed on the substrate placement surface 3a of the flatbed unit 3 (S14).

Next, the printing surface of the substrate 15 having a pretreatment layer made of a pretreatment agent is heated while ink is ejected from the head unit 26 onto the printing surface to perform the printing process (S16).

Specifically, the temperature of the entire printing surface of the substrate 15 is detected by the thermographic camera 6. The control unit 8 controls the heater unit 7 based on the temperature detected by the thermographic camera 6 to heat the entire substrate 15. The control unit 8 calculates, for example, a statistical value of the temperature distribution detected by the thermographic camera 6, and controls the heater unit 7 based on the statistical value. The statistical value may be an average value, a median value, a maximum value, a minimum value, or the like.

Here, since the heating by the heater unit 7 heats the entire substrate 15, if the thermal conductivity of the substrate 15 is not uniform, or if multiple substrates 15a, 15b with different thermal conductivities are heated by the heater unit 7 as described above, it may be difficult to make the temperature uniform across the entire printed surface of the substrate 15 or across the entire printed surfaces of the multiple substrates 15a, 15b.

Therefore, in this embodiment, the control unit 8 independently controls each of the airflow generating units 5a to 5d of the heating unit 5 to generate different volumes of hot air, thereby controlling the temperature to be uniform across the entire printed surface of the substrate 15 or across the entire printed surfaces of multiple substrates 15a, 15b.

More specifically, the control unit 8 moves the shuttle unit 4 and the heating unit 5 backward from the position shown in FIG. 1 to the initial printing position at the rear end of the substrate placement surface 3a.

Then, the control unit 8 moves the shuttle unit 4 and the heating unit 5 from rear to front, and when the temperature sensor 27 reaches the first scanning range, it moves the head unit 26 left and right and detects the temperature of the first scanning range with the temperature sensor 27. At this time, the temperature sensor 27 detects the temperature of each of the areas obtained by dividing the scanning range into four equal parts left and right. The four equal parts are the ranges that are heated by the airflow generating units 5a to 5d, respectively.

The control unit 8 then moves the shuttle unit 4 and the heating unit 5 further forward, and when the head unit 26 reaches the first scanning range, it ejects ink while moving the head unit 26 left and right, and prints the first scanning range. Then, while the head unit 26 is moving left and right in this first scanning range, the temperature sensor 27 detects the temperature of each of the four areas in the second scanning range. Also, while the head unit 26 is printing the first scanning range, the control unit 8 controls the airflow generating units 5a to 5d based on the temperature detected for each area, so that the temperature in each area is uniform.

That is, the control unit 8 performs the printing process while uniformly controlling the temperature of the first scanning range. By using the airflow generating units 5a to 5d to appropriately heat the substrate 15 during the printing process, it is possible to maintain print stability while suppressing the amount of moisture contained in the ink to a level that does not soften the pretreatment layer.

Then, after the printing process of the first scanning range is completed, the control unit 8 moves the shuttle unit 4 and the heating unit 5 further forward. Then, when the head unit 26 reaches the second scanning range, the control unit 8 ejects ink while moving the head unit 26 left and right, and performs the printing process on the first scanning range. Then, while the head unit 26 is moving left and right in this second scanning range, the temperature sensor 27 detects the temperature of each of the four areas of the third scanning range. Also, while the head unit 26 is printing the second scanning range, the control unit 8 controls the airflow generating units 5a to 5d based on the temperature detected for each area, so that the temperature of each area is uniform.

As described above, while performing the printing process of the nth (n is a natural number equal to or greater than 1) scanning range, the control unit 8 detects the temperature of the (n+1)th scanning range using the temperature sensor 27, and while performing the printing process of the nth scanning range, controls the airflow generating units 5a to 5d so that the temperature of each of the four areas of the nth scanning range is uniform. The control unit 8 repeats the above operations while moving the shuttle unit 4 and the heating unit 5.

After the printing process of the substrate 15 is completed, the main drying process is performed (S18). In order to make the printed surface strong, the moisture, solvent, activator, etc. in the ink remaining in the above-mentioned heat printing process are completely evaporated in the main drying process. The main drying is performed in a drying device separate from the inkjet printing device 1 at a temperature higher than the heating temperature during the above-mentioned printing process. Since the solvent and activator in the ink are difficult to volatilize, it is preferable to perform the main drying process at 100°C or higher. As with the drying process of the pretreatment agent, if the substrate 15 is relatively small, a batch-type electric dryer can be used, and if the substrate is large, a conveyor-type continuous dryer can be used.

According to the inkjet printing device 1 of the above embodiment, the heating unit 5 is used to heat the substrate 15 at different temperatures in different parts so that the surface temperature of the printing surface of the substrate 15 becomes uniform during the printing process. This makes it possible to prevent cracks in the printed image and ensure image quality and adhesion when performing a printing process with aqueous ink on a single substrate having partially different thermal conductivities or when performing a printing process with aqueous ink on multiple substrates having different thermal conductivities.

In addition, the heating unit 5 can heat the printing surfaces of multiple substrates 15a, 15b with different thermal conductivities so that the temperature is uniform. This allows printing to be performed on multiple substrates 15a, 15b with different thermal conductivities at once, preventing cracks in the printed image and ensuring image quality and adhesion, while also improving productivity.

In addition, since multiple airflow generating units 5a to 5d are provided to generate heated airflow in a direction along the printed surface of the substrate 15, the printed surface of the substrate 15 can be partially heated with a simple and inexpensive configuration.

In addition to the multiple airflow generating units 5a to 5d, a heater section 7 is provided that heats the substrate 15 from the side opposite the printed surface, allowing the temperature of the printed surface to be controlled more quickly.

In addition, a temperature sensor 27 is provided in front of the head unit 26 in the direction of movement relative to the substrate 15, making it possible to detect the temperature of the printing surface of the substrate 15 immediately before the printing process, and to control the temperature of the printing surface of the substrate 15 with greater precision.

In the inkjet printing apparatus 1 of the present embodiment, the airflow generating units 5a to 5d are used to control the temperature at different parts, but if the heater section 7 is configured to be capable of controlling the temperature at different parts, the temperature of the printing surface of the substrate 15 may be controlled using only the heater section 7. Furthermore, the heating means is not limited to the airflow generating units 5a to 5d and the heater section 7 as in the above embodiment, but a halogen lamp or the like may also be used.
The present invention is not limited to the above-described embodiment, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, all the components shown in the embodiment can be appropriately combined. Of course, various modifications and applications are possible without departing from the spirit of the invention.

Next, we will explain an example of the inkjet printing device 1 according to the above embodiment.

The pretreatment agent was applied to a non-absorbent metal substrate at 5 g/ ^m2 and dried at 100° C. for 5 minutes. Nickel-plated brass having a thickness of 0.5 mm was used as the non-absorbent metal substrate. The non-absorbency was 20 cm/2s.

The pretreatment agent used was a mixture of a polydiallylamine-based cationic water-soluble resin as an ink agglomeration component and a water-based acrylic resin as a binder component.

The temperature of the heater section 7 of the flatbed unit 3 was controlled to 53°C, and the heating unit 5 was controlled so that the substrate surface temperature was uniformly kept at 50°C, and printing was performed. CMYK water-based pigment inks were used. The printed image was a CMYK solid image. As a result, no cracks occurred in the printed image.

On the other hand, when the printing process was performed under the same conditions except for the heating by the heater section 7 and the heating unit 5 during the printing process, severe cracks occurred in the printed image.

The present invention further discloses the following supplementary notes.
(Additional Note)

In the inkjet printing device of the present invention, the heating unit can heat multiple substrates having different thermal conductivities so that the temperature of the printing surface of the substrates is uniform.

In addition, in the inkjet printing device of the present invention, the heating section can have multiple airflow generating sections that generate heated airflows in a direction along the printing surface.

In addition, the inkjet printing device of the present invention can have multiple airflow generating units as well as a heater unit that heats the substrate from the side opposite the printing surface.

In addition, in the inkjet printing device of the present invention, a temperature detection unit can be provided ahead of the head unit in the direction of movement relative to the substrate.

The inkjet printing method of the present invention detects the temperature of the printing surface of the substrate when performing printing processing by ejecting aqueous ink onto a non-absorbent metal substrate coated with a pretreatment agent that causes the aqueous ink to aggregate, and heats the substrate at different temperatures in parts based on the detected temperature so that the temperature of the printing surface of the substrate becomes uniform during printing processing.

1 Inkjet printing device 2 Shuttle base unit 3 Flat bed unit 3a Substrate mounting surface 4 Shuttle unit 5 Heating units 5a to 5d Air flow generating unit 6 Thermographic camera 7 Heater unit 11 Frame unit 12 Sub-scanning drive motor 13A, 13B Sub-scanning drive guide 15 Substrate 15a, 15b Substrate 21 Housing 22 Main scanning drive guide 23 Main scanning drive motor 24 Head lift guide 25 Head lift motor 13A, 13B Sub-scanning drive guide 26 Head unit 27 Temperature sensor 31 Inkjet head 50 Exhaust duct 51 Heater 52 Fan

Claims (6)

a head unit that performs a printing process by ejecting the aqueous ink onto a non-absorbent metal-based substrate that has been coated with a pretreatment agent that causes the aqueous ink to aggregate;
A temperature detection unit that detects the temperature of the printing surface of the substrate;
an inkjet printing apparatus comprising: a heating unit capable of heating the substrate at partially different temperatures during the printing process based on the temperature detected by the temperature detection unit. The inkjet printing device according to claim 1, wherein the heating unit is capable of heating the substrates having different thermal conductivities so that the temperatures of the printing surfaces of the substrates are uniform. The inkjet printing device according to claim 1, wherein the heating unit has a plurality of airflow generating units that generate heated airflows in a direction along the printing surface. The inkjet printing device according to claim 3, further comprising a heater unit that heats the substrate from the side opposite the printing surface, in addition to the plurality of airflow generating units. The inkjet printing device according to claim 1, wherein the temperature detection unit is provided on the front side of the head unit in the direction of movement relative to the substrate. When performing a printing process by discharging the aqueous ink onto a non-absorbent metal substrate to which a pretreatment agent that causes the aqueous ink to aggregate has been applied,
Detecting the temperature of the printing surface of the substrate;
The inkjet printing method further comprises heating the substrate at different temperatures during the printing process based on the detected temperature.