JP6955319B2 - Inkjet printer and inkjet printing method - Google Patents

Description

The present invention relates to an inkjet printer and an inkjet printing method for performing printing on a medium with solvent UV ink.

Conventionally, as an inkjet printer that prints on a medium with a solvent UV ink, the polymerization of at least one of a coloring material, a monomer and an oligomer cured by polymerization, and at least one of the monomer and an oligomer by irradiation with ultraviolet rays is started. An inkjet head that ejects solvent UV ink containing at least a photopolymerization initiator and a volatile organic solvent that volatilizes when heated toward the medium, and a solvent UV that is ejected by the inkjet head and landed on the medium. It is provided with a print heater that volatilizes a volatile organic solvent in the ink by heating, and a UV irradiation means that cures the solvent UV ink by irradiating the solvent UV ink ejected by the inkjet head and landed on the medium with ultraviolet rays. Is known (see Patent Document 1).

In a conventional inkjet printer, the volatile organic solvent in the solvent UV ink ejected by the inkjet head and landed on the medium is volatilized by heating with a print heater, and then the solvent UV ink is irradiated with ultraviolet rays by UV irradiation means. This cures the solvent UV ink. That is, after the volatile organic solvent in the solvent UV ink ejected by the inkjet head and landed on the medium is volatilized, there is a time until the solvent UV ink is cured. Therefore, the solvent UV ink ejected by the inkjet head and landed on the medium undergoes surface flattening, that is, leveling, with the passage of time until it is cured. Therefore, the brightness of the solvent UV ink ejected by the inkjet head and landed on the medium is improved after curing.

By using the solvent UV ink, the conventional inkjet printer can perform high-luminance printing, that is, gloss printing, as described above.

Here, the solvent UV ink is diluted with a volatile organic solvent unlike a normal UV ink. Therefore, the solvent UV ink is more likely to cause bleeding due to the volatile organic solvent after being ejected by the inkjet head and landed on the medium as compared with the ordinary UV ink.

Therefore, in order to suppress the bleeding of the solvent UV ink on the medium, the heating temperature of the print heater that volatilizes the volatile organic solvent in the solvent UV ink ejected by the inkjet head and landed on the medium is raised. , It is conceivable to complete the volatilization of the volatile organic solvent in the solvent UV ink at an early stage.

However, if the heating temperature of the print heater that volatilizes the volatile organic solvent in the solvent UV ink landed on the medium is raised, the medium may be damaged, such as cockling.

Therefore, conventionally, by suppressing the amount of solvent UV ink ejected by the inkjet head and landing on the medium, the total amount of the volatile organic solvent in the solvent UV ink landed on the medium is suppressed, thereby, on the medium. Suppresses bleeding of solvent UV ink in.

Japanese Unexamined Patent Publication No. 2014-172224

With the recent spread of solvent UV ink, there is a demand for printing with solvent UV ink on various media such as a medium that easily absorbs the landed solvent UV ink inside. ..

In addition, there is a demand for high-density printing with solvent UV ink, for example, for printing black to be blacker.

It is conceivable to meet these recent demands by increasing the amount of solvent UV ink ejected by the inkjet head and landed on the medium. However, if the amount of the solvent UV ink ejected by the inkjet head and landed on the medium is increased, the problem of bleeding of the solvent UV ink on the medium occurs as described above. Therefore, it is not possible to simply increase the amount of solvent UV ink ejected by the inkjet head and landed on the medium, and there is a problem that the above-mentioned recent demand cannot be met.

Therefore, the present invention presents an inkjet printer and an inkjet printing method capable of appropriately suppressing bleeding of solvent UV ink on a medium even if a large amount of solvent UV ink capable of performing gloss printing is landed on the medium. The purpose is to provide.

The inkjet printer of the present invention is heated by a coloring material, at least one of a monomer and an oligomer that is cured by polymerization, and a photopolymerization initiator that initiates the polymerization of at least one of the monomer and the oligomer by irradiation with ultraviolet rays. An inkjet head that ejects a solvent UV ink containing at least a volatile organic solvent that volatilizes to the medium, and the volatileness in the solvent UV ink that is ejected by the inkjet head and landed on the medium. A heating means for volatilizing an organic solvent by heating and a UV irradiation means for curing the solven UV ink by irradiating the solvent UV ink ejected by the inkjet head and landing on the medium with ultraviolet rays are provided. The UV irradiating means irradiates the solvent UV ink while being heated by the heating means with ultraviolet rays.

With this configuration, the inkjet printer of the present invention simultaneously performs volatilization of a volatile organic solvent by heating and curing by irradiation with ultraviolet rays with respect to the solvent UV ink ejected by the inkjet head and landed on the medium. Therefore, even if a large amount of solvent UV ink capable of performing gloss printing is landed on the medium as compared with the conventional case, it is possible to appropriately suppress the bleeding of the solvent UV ink on the medium. If the solvent UV ink is irradiated with ultraviolet rays before the volatile organic solvent in the solvent UV ink ejected by the inkjet head and landed on the medium is completely volatilized by heating, the solvent UV ink has not yet been volatilized. Those skilled in the art may be concerned that the volatile organic solvent is trapped inside the cured solvent UV ink and cannot be volatilized. However, as a result of diligent research, the inventor of the present invention has a large number of pores in the polymer obtained by curing the monomer (oligomer) contained in the solvent UV ink. Therefore, the solvent UV ink after curing has a large number of pores. It was found that the volatile organic solvent trapped inside the solvent is discharged to the outside of the solvent UV ink through the above-mentioned pores. That is, even if the inventor of the present invention simultaneously performs volatilization of the volatile organic solvent by heating and curing by irradiation with ultraviolet rays on the solvent UV ink ejected by the inkjet head and landed on the medium. , It was found that the volatile organic solvent can be properly volatilized.

Further, the inkjet printer of the present invention includes a control unit that moves the inkjet head relative to the medium in the main scanning direction and prints on the medium in the main scanning direction by the inkjet head. The UV irradiation means emits ultraviolet rays to the solvent UV ink ejected by the inkjet head and landed on the medium during one printing in the main scanning direction by the inkjet head. You may irradiate.

With this configuration, the inkjet printer of the present invention exposes the solvent UV ink to ultraviolet light before the volatile organic solvent in the solvent UV ink ejected by the inkjet head and landed on the medium is completely volatilized by heating. Can be irradiated.

Further, the inkjet printer of the present invention includes a carriage on which the inkjet head is mounted, and the control unit moves the carriage relative to the medium in the main scanning direction to the medium. On the other hand, the inkjet head may be moved relative to the main scanning direction, and the UV irradiation means may be mounted on the carriage on the upstream side of the inkjet head in the moving direction of the carriage with respect to the medium.

With this configuration, the inkjet printer of the present invention can irradiate the solvent UV ink immediately after being ejected by the inkjet head and landed on the medium with ultraviolet rays.

Further, in the inkjet printer of the present invention, the solvent UV ink ejected by the inkjet head and landed on the medium is heated by the heating means from the time when the solvent UV ink is landed on the medium. May be started.

With this configuration, the inkjet printer of the present invention finishes volatilization of the volatile organic solvent by heating and curing by irradiation of ultraviolet rays with respect to the solvent UV ink ejected by the inkjet head and landed on the medium at an early stage. Therefore, the printing speed can be improved.

Further, in the inkjet printer of the present invention, the heating means may execute heating of the solvent UV ink ejected by the inkjet head and landed on the medium by heating the medium.

With this configuration, the inkjet printer of the present invention heats the solvent UV ink at a sufficient temperature from the time when the solvent UV ink is landed on the medium by heating the medium before the solvent UV ink is landed on the medium. Therefore, the printing speed can be further improved.

Further, the inkjet printer of the present invention includes a metal halide lamp capable of simultaneously performing heating and irradiation with ultraviolet rays, and the metal halide lamp may constitute both the heating means and the UV irradiation means. ..

With this configuration, the inkjet printer of the present invention realizes both heating and irradiation with ultraviolet rays by the metal halide lamp, so that the configuration can be simplified.

The inkjet printing method of the present invention is heated by a coloring material, at least one of a monomer and an oligomer that is cured by polymerization, and a photopolymerization initiator that initiates the polymerization of at least one of the monomer and the oligomer by irradiation with ultraviolet rays. An ink ejection step of ejecting a solvent UV ink containing at least a volatile organic solvent volatilized by the ink toward a medium by an inkjet printer, and the solvent UV ink ejected by the inkjet head and landed on the medium. A heating step of volatilizing the volatile organic solvent inside by heating, and UV irradiation for curing the solven UV ink by irradiating the solvent UV ink ejected by the inkjet head and landed on the medium with ultraviolet rays. The UV irradiation step is characterized by irradiating the solvent UV ink being heated by the heating step with ultraviolet rays.

With this configuration, the inkjet printing method of the present invention simultaneously executes volatilization of a volatile organic solvent by heating and curing by irradiation with ultraviolet rays on the solvent UV ink ejected by the inkjet head and landed on the medium. Therefore, even if a large amount of solvent UV ink capable of performing gloss printing is landed on the medium as compared with the conventional case, it is possible to appropriately suppress the solvent UV ink from bleeding on the medium.

The inkjet printer and the inkjet printing method of the present invention can appropriately suppress bleeding of the solvent UV ink on the medium even if a large amount of the solvent UV ink capable of performing gloss printing is landed on the medium as compared with the conventional case.

It is a perspective view of the inkjet printer which concerns on one Embodiment of this invention. It is a front view of a part of the inkjet printer shown in FIG. It is a side view of a part of the inkjet printer shown in FIG. It is a block diagram of the inkjet printer shown in FIG. (A) It is a figure which shows an example of the dot formed on the medium by the solvent UV ink immediately after being ejected by the inkjet head shown in FIG. 1 and landing on a medium. (B) It is a figure which shows an example of the dot shown in FIG. 5A in the case where a volatile organic solvent is volatilized by heating of a print heater. (A) is a diagram showing an example of dots formed on the medium by the solvent UV ink immediately after being ejected by the inkjet head shown in FIG. 1 and landed on the medium, with the example shown in FIG. 5 (a). Is a diagram showing a different example. (B) It is a figure which shows an example of the dot shown in FIG. 6A in the case where a volatile organic solvent is volatilized by heating of a print heater. (A) It is a top view of a part of the inkjet printer which concerns on one Embodiment of this invention, and is the figure which shows the example different from the example shown in FIG. (B) It is a side view of a part of the inkjet printer shown in FIG. 7 (a). (A) It is a top view of a part of the inkjet printer which concerns on one Embodiment of this invention, and is the figure which shows the example different from the example shown in FIG. 1 and FIG. (B) It is a side view of a part of the inkjet printer shown in FIG. 8 (a). (A) It is a top view of a part of the inkjet printer which concerns on one Embodiment of this invention, and is the figure which shows the example different from the example shown in FIG. 1, FIG. 7 and FIG. (B) is a plan view of a part of the inkjet printer shown in FIG. 9A, showing a state different from the state shown in FIG. 9A. It is a side view of a part of the inkjet printer which concerns on one Embodiment of this invention, and is the figure which shows the example different from the example shown in FIG. 1, FIG. 7, FIG. 8 and FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

First, the configuration of the inkjet printer according to the present embodiment will be described.

FIG. 1 is a perspective view of the inkjet printer 10 according to the present embodiment.

As shown in FIG. 1, the inkjet printer 10 extends in the main scanning direction with the medium conveying device 11 that conveys the medium 90 such as paper in the sub-scanning direction indicated by the arrow 10b orthogonal to the main scanning direction indicated by the arrow 10a. A guide rail 12 that is mounted on the guide rail 12, a carriage 13 that is movably supported by the guide rail 12 in the main scanning direction, and an inkjet head that is mounted on the carriage 13 and ejects solvent UV (ultraviolet) ink toward the medium 90. A 14 and an ultraviolet irradiation device 15 mounted on a carriage 13 and an ink tank (not shown) for storing a solvent UV ink supplied to the inkjet head 14 are provided.

The ultraviolet irradiation device 15 is a device that cures the solven UV ink by irradiating the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 with ultraviolet rays, and constitutes a UV irradiation means. The ultraviolet irradiation device 15 is arranged on both sides of the inkjet head 14 in the main scanning direction indicated by the arrow 10a. The ultraviolet irradiation device 15 may be arranged on only one side of the inkjet head 14 in the main scanning direction. The ultraviolet irradiation device 15 is composed of, for example, a UV-LED (Light Emitting Diode) unit.

The solvent UV ink discharged by the inkjet head 14 is a photopolymerization initiator that initiates the polymerization of at least one of a coloring material, a monomer and an oligomer that is cured by polymerization, and at least one of the monomer and an oligomer when irradiated with ultraviolet rays. And an ink containing at least a volatile organic solvent that volatilizes when heated. As the coloring material, for example, pigments such as white and process colors, aluminum particles, and the like can be adopted. For example, solvent UV ink is composed of a coloring material, at least one of a monomer and an oligomer, and a photopolymerization initiator, and a volatile organic solvent is added to a UV curable ink having a viscosity of 20 mPa · sec or more (room temperature 25 ° C.). This is an ink having a viscosity of 3 mPa · sec or more and 18 mPa · sec or less (room temperature 25 ° C.).

FIG. 2 is a front view of a part of the inkjet printer 10. FIG. 3 is a side view of a part of the inkjet printer 10.

As shown in FIGS. 2 and 3, the inkjet printer 10 uses a print heater 16 as a heating means for heating to volatilize the volatile organic solvent in the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90. , The inkjet head 14 is provided in the ejection direction of the solvent UV ink by the inkjet head 14. The print heater 16 is composed of, for example, a rubber heater.

FIG. 4 is a block diagram of the inkjet printer 10.

As shown in FIG. 4, the inkjet printer 10 includes the above-mentioned medium transfer device 11, the inkjet head 14, and the print heater 16, and the carriage 13 (see FIG. 1) in the main scanning direction indicated by the arrow 10a (see FIG. 1). A carriage drive device 17 that moves a device, a communication unit 18 that is a communication device that communicates with an external device, and storage such as an inkjet (Electrically Erasable Program Read Only Memory) and an HDD (Hard Disk Drive) that store various data. It includes a storage unit 19 which is a device, and a control unit 20 which controls the entire inkjet printer 10.

The control unit 20 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores programs and various data in advance, and a RAM (Random Access Memory) used as a work area of the CPU. ing. The CPU is designed to execute a program stored in the ROM or the storage unit 19.

Next, the operation of the inkjet printer 10 will be described.

When print data is transmitted from a computer such as a PC (Personal Computer) (not shown), the control unit 20 prints an image based on the transmitted print data on the medium 90. Specifically, the control unit 20 first sufficiently heats the medium 90 by the print heater 16. Next, the control unit 20 ejects ink to the medium 90 by the inkjet head 14 while moving the carriage 13 with respect to the medium 90 in the main scanning direction indicated by the arrow 10a by the carriage driving device 17. Further, when the ink jet head 14 ejects ink to the medium 90, the control unit 20 causes the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 to be irradiated with ultraviolet rays by the ultraviolet irradiation device 15. Cure UV ink. That is, the ultraviolet irradiation device 15 cures the solven UV ink by irradiating the solven UV ink being ejected by the inkjet head 14 and landing on the medium 90 and being heated by the print heater 16 with ultraviolet rays. .. The control unit 20 transfers the medium 90 to the carriage 13 each time printing by the inkjet head 14 and the ultraviolet irradiation device 15 is completed during one movement of the carriage 13 with respect to the medium 90 in the main scanning direction indicated by the arrow 10a. It is moved by the medium transfer device 11 in the sub-scanning direction indicated by the arrow 10b.

The dots formed on the medium 90 by the solvent UV ink when the control unit 20 operates as described above will be described.

FIG. 5A is a diagram showing an example of dots 31 formed on the medium 90 by the solvent UV ink immediately after being ejected by the inkjet head 14 and landed on the medium 90. FIG. 5B is a diagram showing an example of dots 31 when the volatile organic solvent is volatilized by heating the print heater 16.

As shown in FIG. 5A, the dots 31 formed on the medium 90 by the solvent UV ink immediately after being ejected by the inkjet head 14 and landed on the medium 90 are hemispherical. Here, the medium 90 is sufficiently heated by the print heater 16. Therefore, the volatile organic solvent of the dots 31 shown in FIG. 5 (a) is volatilized by heating the print heater 16 from the time when the dots 31 are formed on the medium 90, and as shown in FIG. 5 (b), the surface of the dots 31 is volatile. Flattening, or leveling, occurs. Further, since the viscosity of the dot 31 is improved by volatilizing the volatile organic solvent, it becomes difficult to bleed. Then, the dots 31 are cured in the state shown in FIG. 5B by being irradiated with ultraviolet rays by the ultraviolet irradiation device 15, and are not completely blurred.

As described above, in the inkjet printer 10, the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 is subjected to volatilization of a volatile organic solvent by heating and curing by irradiation with ultraviolet rays. Since they are executed at the same time, even if a large amount of solven UV ink capable of performing gloss printing is landed on the medium 90 as compared with the conventional case, it is possible to appropriately suppress the solvent UV ink from bleeding on the medium 90.

When a large amount of solvent UV ink is landed on the medium 90, the film thickness of the solvent UV ink landed on the medium 90 becomes thick, so that the portion of the medium 90 covered with the solvent UV ink is concealed by the solvent UV ink. Can be improved.

When the color material of the solvent UV ink is scaly aluminum particles, as shown in FIG. 6A, the scaly aluminum particles 32 are ejected by the inkjet head 14 to the medium 90. Inside the dots 31 formed on the medium 90 by the solvent UV ink immediately after landing, they are oriented in various directions. However, as shown in FIG. 6B, when the surface of the dot 31 is flattened, that is, leveling occurs as the volatile organic solvent is volatilized, the particles 32 have the surface flattened dot. Inside the 31, it is aligned substantially parallel to the flat surface of the surface of the dots 31. Therefore, when the color material of the solvent UV ink is the scaly aluminum particles 32, the inkjet printer 10 obtains both the brightness and the hiding power of the solvent UV ink printed on the medium 90 on the surface of the dot 31. This can be improved by the particles 32 aligned substantially parallel to the flat surface. This effect can be obtained even if the particle size of the aluminum particles 32 is small. For example, the inkjet printer 10 can realize brightness having sufficient metallic luster and sufficient hiding property even when the particle size of the aluminum particles 32 is 0.5 μm or less.

The ultraviolet irradiation device 15 is mounted on the carriage 13 on the upstream side of the inkjet head 14 in the moving direction of the carriage 13 with respect to the medium 90 in the main scanning direction. With this configuration, the inkjet printer 10 is directed to the solvent UV ink immediately after being ejected by the inkjet head 14 and landed on the medium 90 on the upstream side of the inkjet head 14 in the direction of movement of the carriage 13 with respect to the medium 90 in the main scanning direction. Ultraviolet rays can be irradiated by the ultraviolet irradiation device 15 of the above.

In the inkjet printer 10, by adjusting the irradiation direction of ultraviolet rays by the ultraviolet irradiation device 15, the solvent UV ink immediately after being ejected by the inkjet head 14 and landed on the medium 90 is mainly used for the carriage 13 with respect to the medium 90. Ultraviolet rays can also be irradiated by the ultraviolet irradiation device 15 on the downstream side of the inkjet head 14 in the moving direction in the scanning direction.

Similarly, in the inkjet printer 10, when the ultraviolet irradiation device 15 is arranged on the carriage 13 on the upstream side of the inkjet head 14, for example, as shown in FIG. 7, in the moving direction of the carriage 13 with respect to the medium 90 in the sub-scanning direction. Even when the ultraviolet irradiation device 15 is arranged on the carriage 13 so as to be displaced from the inkjet head 14 in the sub-scanning direction, it is ejected by the inkjet head 14 by adjusting the irradiation direction of ultraviolet rays by the ultraviolet irradiation device 15. The solvent UV ink immediately after being landed on the medium 90 can be irradiated with ultraviolet rays by the ultraviolet irradiation device 15. In FIG. 7B, the broken line indicates the ultraviolet irradiation range of the ultraviolet irradiation device 15. However, in FIG. 7B, in order to facilitate understanding of the ultraviolet irradiation direction, the ultraviolet irradiation range by the ultraviolet irradiation device 15 is drawn toward the front side of the carriage 13 toward the drawing, but it is actually The ultraviolet irradiation device 15 irradiates the medium 90 with ultraviolet rays through a hole formed in the carriage 13.

Further, in the inkjet printer 10, even if the ultraviolet irradiation device 15 is not mounted on the carriage 13, the ultraviolet irradiation device 15 irradiates the solvent UV ink immediately after being ejected by the inkjet head 14 and landed on the medium 90. can do.

For example, as shown in FIG. 8, in the inkjet printer 10, the ultraviolet irradiation device 15 is not mounted on the carriage 13, and the entire range of one printing in the main scanning direction by the inkjet head 14 is irradiated with ultraviolet rays at once. In the case of an apparatus, immediately after being ejected by the inkjet head 14 and landed on the medium 90 by continuing to irradiate ultraviolet rays by the ultraviolet irradiation apparatus 15 during one printing in the main scanning direction by the inkjet head 14. The solvent UV ink of No. 1 can be irradiated with ultraviolet rays by the ultraviolet irradiation device 15. In FIG. 8B, the broken line indicates the ultraviolet irradiation range of the ultraviolet irradiation device 15.

Further, as shown in FIG. 9, the inkjet printer 10 is ejected by the inkjet head 14 even when the ultraviolet irradiation device 15 is not mounted on the carriage 13 and the ultraviolet irradiation direction can be changed. Immediately after being ejected by the inkjet head 14 and landing on the medium 90 by automatically changing the irradiation direction of ultraviolet rays by the ultraviolet irradiation device 15 toward the solvent UV ink immediately after being landed on the medium 90. The solvent UV ink can be irradiated with ultraviolet rays by the ultraviolet irradiation device 15. In FIG. 9, the broken line indicates the ultraviolet irradiation range of the ultraviolet irradiation device 15. However, in FIG. 9, in order to facilitate understanding of the ultraviolet irradiation direction, the ultraviolet irradiation range of the ultraviolet irradiation device 15 is set toward the drawing from the ultraviolet irradiation device 15, the guide rail 12, the carriage 13, and the inkjet head 14. Although drawn on the front side, the ultraviolet irradiation device 15 actually irradiates the space between the ultraviolet irradiation device 15, the guide rail 12, the carriage 13, and the inkjet head 14 with ultraviolet rays.

The ultraviolet irradiation device 15 preferably irradiates the solvent UV ink immediately after being ejected by the inkjet head 14 and landed on the medium 90 with ultraviolet rays, but during one printing in the main scanning direction by the inkjet head 14. In addition, the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 in this one printing may be irradiated with ultraviolet rays. With this configuration, the inkjet printer 10 emits ultraviolet rays to the solvent UV ink before the volatile organic solvent in the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 is completely volatilized by heating. Can be irradiated.

For example, in the inkjet printer 10, as shown in FIG. 8, the ultraviolet irradiation device 15 is not mounted on the carriage 13, and the entire range of one printing in the main scanning direction by the inkjet head 14 is irradiated with ultraviolet rays at once. In the case of an apparatus, the medium 90 is ejected by the inkjet head 14 by irradiating the ultraviolet irradiation device 15 with ultraviolet rays a specific number of times at a specific timing during one printing in the main scanning direction by the inkjet head 14. The solvent UV ink landed on the printer can be cured.

The solvent UV ink ejected by the inkjet head 14 may be irradiated with ultraviolet rays by the ultraviolet irradiation device 15 during flight before being landed on the medium 90.

In the inkjet printer 10, heating of the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 by the print heater 16 is started from the time when the solvent UV ink is landed on the medium 90. Therefore, the inkjet printer 10 finishes volatilization of the volatile organic solvent by heating and curing by irradiation of ultraviolet rays with respect to the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 at an early stage. Therefore, the printing speed can be improved.

In the inkjet printer 10, the print heater 16 heats the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 by heating the medium 90. Therefore, the inkjet printer 10 heats the solvent UV ink at a sufficient temperature from the time when the solvent UV ink is landed on the medium 90 by heating the medium 90 before the solvent UV ink is landed on the medium 90. Therefore, the printing speed can be further improved.

In the inkjet printer 10, heating of the solvent UV ink ejected by the inkjet head 14 and landed on the medium 90 by the heating means is started after the time when the solvent UV ink is landed on the medium 90. You may.

The inkjet printer 10 heats the solvent UV ink on the medium 90 by the print heater 16 from the side opposite to the inkjet head 14 side with respect to the medium 90. However, the inkjet printer 10 may be provided with a heating means for heating the solvent UV ink on the medium 90 from the inkjet head 14 side with respect to the medium 90 instead of the print heater 16, or may be added to the print heater 16. You may prepare for it. For example, as shown in FIG. 10, the inkjet printer 10 may include an infrared lamp 21 that heats the solvent UV ink on the medium 90 from the inkjet head 14 (see FIG. 2) side with respect to the medium 90.

The infrared lamp 21 shown in FIG. 10 can heat the solvent UV ink landed on the medium 90 by heating the medium 90 in advance, or the solvent UV ink itself landed on the medium 90 is used as the medium 90. It is also possible to heat directly without using the ink.

The ultraviolet irradiation device 15 may be a metal halide lamp capable of simultaneously performing heating and irradiation of ultraviolet rays. When the ultraviolet irradiation device 15 is a metal halide lamp, the ultraviolet irradiation device 15 constitutes both a heating means and a UV irradiation means. When the ultraviolet irradiation device 15 is a metal halide lamp, the inkjet printer 10 realizes both heating and irradiation of ultraviolet rays by the ultraviolet irradiation device 15 as a metal halide lamp, so that the configuration can be simplified.

The inkjet printer 10 cures the solvent UV ink by irradiating the inkjet head 14 that ejects the solvent UV ink toward the medium 90 and the solvent UV ink that is ejected by the inkjet head 14 and landed on the medium 90 with ultraviolet rays. Since the ultraviolet irradiation device 15 is installed on the same carriage 13, the ultraviolet irradiation device extending in the direction indicated by the arrow 10a on the downstream side in the transport direction of the medium 90 with respect to the inkjet head 14 is referred to as the carriage 13. The ultraviolet irradiation device can be miniaturized as compared with the configuration provided separately.

In the inkjet printer 10, since the inkjet head 14 and the ultraviolet irradiation device 15 are installed on the same carriage 13, the ultraviolet irradiation device is applied to the solvent UV ink immediately after being ejected by the inkjet head 14 and landed on the medium 90. Since the ultraviolet rays can be efficiently irradiated by the method 15, the energy consumption for irradiating the ultraviolet rays by the ultraviolet irradiation device can be suppressed.

Since the inkjet printer 10 can cure the solvent UV ink by irradiating the solvent UV ink immediately after being ejected by the inkjet head 14 and landing on the medium 90 with ultraviolet rays by the ultraviolet irradiation device 15, the ink jet printer 10 can cure the solvent UV ink on the medium 90. It is possible to prevent the solvent UV ink from bleeding. Therefore, the inkjet printer 10 can be superimposed on the medium 90 while curing the dots of the solvent UV ink, and has a wide expression range from a light density expressed by overlapping a small amount to a dark density expressed by overlapping a large amount. Can be printed with.

Since the inkjet printer 10 can prevent the solvent UV ink on the medium 90 from bleeding, it is less necessary to design the solvent UV ink so that the solvent UV ink in the liquid state does not bleed, and the solvent UV ink is reduced. The degree of freedom in designing can be improved.

In the present embodiment, the inkjet printer 10 includes only one inkjet head 14. However, the inkjet printer 10 may include a plurality of inkjet heads 14. When the inkjet printer 10 includes a plurality of inkjet heads 14, the color material of the solvent UV ink discharged from the inkjet heads 14 may be different for each of the plurality of inkjet heads 14.

In the present embodiment, the inkjet printer 10 moves the medium 90 relative to the inkjet head 14 in the sub-scanning direction by moving the medium 90 in the sub-scanning direction indicated by the arrow 10b. However, the inkjet printer 10 may move the inkjet head 14 relative to the medium 90 in the sub-scanning direction by moving the inkjet head 14 in the sub-scanning direction.

10 Inkjet printer 14 Inkjet head 15 Ultraviolet irradiation device (UV irradiation means)
16 Print heater (heating means)
21 Infrared lamp (heating means)
90 media

Claims (8)

Coloring materials that are scaly particles and
With at least one of the monomers and oligomers that cure by polymerization,
A photopolymerization initiator that initiates the polymerization of at least one of a monomer and an oligomer upon irradiation with ultraviolet light.
An inkjet head that ejects a solvent UV ink containing at least a volatile organic solvent that volatilizes by heating toward a medium,
A heating means for volatilizing the volatile organic solvent in the dots of the solvent UV ink ejected by the inkjet head and landing on the medium by heating.
A UV irradiation means for curing the solvent UV ink by irradiating the dots of the solvent UV ink ejected by the inkjet head and landing on the medium with ultraviolet rays is provided.
The heating means causes leveling, which is the flattening of the surface of the dots, by volatilizing the volatile organic solvent in the dots while being irradiated with ultraviolet rays by the UV irradiation means by heating. The coloring material is aligned within the dots substantially parallel to the flat surface of the surface.
The UV irradiating means irradiates the dots of the solvent UV ink being heated by the heating means with ultraviolet rays having an intensity that allows the leveling caused by the volatilization of the volatile organic solvent. A featured inkjet printer. The inkjet printer according to claim 1, wherein the coloring material is scaly aluminum particles. A control unit is provided which moves the inkjet head relative to the medium in the main scanning direction and prints on the medium in the main scanning direction by the inkjet head.
During one printing in the main scanning direction by the inkjet head, the UV irradiation means emits ultraviolet rays to the solvent UV ink ejected by the inkjet head and landed on the medium in this one printing. The inkjet printer according to claim 1 or 2, wherein the ink jet printer is characterized by irradiating. A carriage equipped with the inkjet head is provided.
The control unit moves the carriage relative to the medium in the main scanning direction, thereby moving the inkjet head relative to the medium in the main scanning direction.
The inkjet printer according to claim 3, wherein the UV irradiation means is mounted on the carriage on the upstream side of the inkjet head in the moving direction of the carriage with respect to the medium. The claim is characterized in that heating of the solvent UV ink ejected by the inkjet head and landed on the medium by the heating means is started from the time when the solvent UV ink is landed on the medium. The inkjet printer according to any one of items 1 to 4. The inkjet printer according to claim 5, wherein the heating means heats the solvent UV ink ejected by the inkjet head and landed on the medium by heating the medium. Equipped with a metal halide lamp that can simultaneously heat and irradiate ultraviolet rays
The inkjet printer according to any one of claims 1 to 6, wherein the metal halide lamp constitutes both the heating means and the UV irradiation means. Coloring materials that are scaly particles and
With at least one of the monomers and oligomers that cure by polymerization,
A photopolymerization initiator that initiates the polymerization of at least one of a monomer and an oligomer upon irradiation with ultraviolet light.
An ink ejection process in which a solvent UV ink containing at least a volatile organic solvent that volatilizes when heated is ejected toward a medium by an inkjet head of an inkjet printer.
A heating step of heating to volatilize the volatile organic solvent in the dots of the solvent UV ink ejected by the inkjet head and landed on the medium.
A UV irradiation step of curing the solvent UV ink by irradiating the dots of the solvent UV ink ejected by the inkjet head and landing on the medium with ultraviolet rays is provided.
In the heating step, the volatile organic solvent in the dots while being irradiated with ultraviolet rays by the UV irradiation step is volatilized by heating to cause leveling, which is the flattening of the surface of the dots. This is a step of aligning the coloring material in the dots substantially parallel to the flat surface of the surface.
The UV irradiation step is a step of irradiating the dots of the solvent UV ink while being heated by the heating step with ultraviolet rays having an intensity that allows the leveling caused by the volatilization of the volatile organic solvent. An inkjet printing method characterized by being present.

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