JP2015091662A - Control method of droplet discharge device, droplet discharge device and ink set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of a droplet discharge device capable of forming an excellent image for each printing mode.SOLUTION: A droplet discharge device includes: a head for discharging droplets of a radiation-curable ink composition and causing the droplets to adhere to a recording medium; and irradiation means for irradiating the droplets adhering to the recording medium with active radiation. A control method of the droplet discharge device has: a first printing mode using at least a first radiation-curable ink composition; and a second printing mode using the first radiation-curable ink composition and a second radiation-curable ink composition not used by the first printing mode. In the control method of the droplet discharge device, one of the first printing mode and the second printing mode is selected and printing is performed, and energy per unit area imparted to the droplets by the irradiation means in the first printing mode is different from that in the second printing mode.

Description

  The present invention relates to a method for controlling a droplet discharge device, and a droplet discharge device and an ink set used therefor.

  In recent years, development of radiation-curable inks that are cured by ultraviolet rays, electron beams, or other radiation has been promoted. Such a radiation curable ink is used as one of the reasons for having a quick drying property in recording on a non-absorbing medium that does not absorb or hardly absorbs ink such as plastic, glass, and coated paper. The radiation curable ink is composed of, for example, a polymerizable monomer, a polymerization initiator, a pigment and other additives.

  By the way, such a radiation curable ink is used to discharge radiation curable ink droplets onto a recording medium by an ink jet recording apparatus, and then the ink is cured by irradiating actinic radiation. It is known to form an image.

  For example, Patent Document 1 discloses that an actinic ray is applied to actinic ray curable ink landed on a recording medium by an irradiating unit using an inkjet recording apparatus having one head and irradiation units on both sides of the head. A method for forming an image by irradiation is described.

Japanese Patent No. 4147943

  In the image forming method using the ink jet recording apparatus described in Patent Document 1, all the actinic ray curable ink landed on the recording medium is given uniform energy by the irradiation means. At this time, in order to perform printing (for example, color printing) using a plurality of actinic ray curable inks, it is necessary to set irradiation conditions so that preferable energy is applied to all actinic ray curable inks. For this reason, when performing printing using a plurality of active curable inks, it may not be possible to set irradiation conditions most suitable for each active light curable ink.

  One of the objects according to some aspects of the present invention is to provide a method for controlling a droplet discharge device capable of forming a good image for each printing mode.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the method for controlling the droplet discharge apparatus according to the present invention is as follows:
A head for ejecting droplets of a radiation curable ink composition to adhere to a recording medium;
An irradiation unit that irradiates the droplets attached to the recording medium with active radiation;
A first printing mode using at least the first radiation curable ink composition;
A second print mode using the first radiation curable ink composition and a second radiation curable ink composition that is not used in the first print mode;
Printing by selecting the first printing mode and the second printing mode;
The energy per unit area given to the droplets by the irradiation means is different between the first printing mode and the second printing mode.

  According to the method for controlling a droplet discharge device according to Application Example 1, a good image can be formed for each print mode.

[Application Example 2]
In application example 1,
The first radiation curable ink composition is a black ink composition containing a black coloring material,
The second radiation curable ink composition is a color ink composition containing a color material,
The first printing mode is a monochrome printing mode using the black ink composition,
The second printing mode may be a color printing mode that uses at least the black ink composition and the color ink composition.

[Application Example 3]
In application example 1,
The first radiation curable ink composition is a first color ink composition containing a color material.
The second radiation curable ink composition is a second color ink composition different from the first color ink composition,
The first printing mode is a first color printing mode using a first color ink composition,
The second printing mode may be a second color printing mode that uses at least the first color ink composition and the second color ink composition.

[Application Example 4]
In any one of Application Examples 1 to 3,
In each of the first printing mode and the second printing mode, after the droplets of the radiation curable ink composition are attached to the recording medium, the droplets are collectively irradiated with actinic radiation. Can do.

[Application Example 5]
In any one of Application Examples 1 to 4,
The droplets can be irradiated with the active radiation within 500 ms after adhering to the recording medium.

[Application Example 6]
In any one of Application Examples 1 to 5,
The energy per unit area [E1 (mJ / cm ² ) given to the droplets with respect to the energy per unit area [E ₉₀ (mJ / cm ² )] for curing 90% of the ink composition used in the first printing mode. ² )] ratio [E1 / E ₉₀ (%)] and
The energy per unit area [E1 (mJ / cm ² ) given to the droplets with respect to the energy per unit area [E ₉₀ (mJ / cm ² )] for curing the ink composition used in the second printing mode by 90%. ² )] ratio [E1 / E ₉₀ (%)], the difference can be within 30%.

[Application Example 7]
One aspect of the droplet discharge device according to the present invention is:
A droplet discharge device used in the method for controlling a droplet discharge device according to any one of Application Examples 1 to 6,
The head moves along a predetermined direction;
The irradiation means is provided on at least one side of the head in the predetermined direction.

[Application Example 8]
One aspect of the ink set according to the present invention is:
An ink set including a first ink composition and a second ink composition used in the method for controlling a droplet discharge device according to any one of Application Example 1 to Application Example 6,
Comprising a plurality of radiation curable ink compositions;
The energy per unit area for curing the radiation curable ink composition by 90% is the highest among the plurality of radiation curable ink compositions of the black ink composition containing a black coloring material.

The perspective view which shows typically the droplet discharge apparatus which concerns on this embodiment. FIG. 4 is a schematic diagram illustrating a rear surface of a carriage of the droplet discharge device according to the embodiment. FIG. 4 is a schematic diagram illustrating a bottom surface of a carriage of the droplet discharge device according to the present embodiment.

  Hereinafter, preferred embodiments of the present invention will be described. Embodiment described below demonstrates an example of this invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention. Note that not all of the configurations described in the following embodiments are indispensable constituent requirements of the present invention.

1. Droplet Discharge Device A droplet discharge device according to an embodiment of the present invention includes a head that discharges droplets of a radiation curable ink composition and attaches them to a recording medium, and a droplet that adheres to the recording medium. An irradiation means for irradiating actinic radiation, and includes a first printing mode using a first ink set including the first ink composition, and the first ink composition and the first ink set. A second printing mode using a second ink set with no second ink composition, and printing by selecting the first printing mode and the second printing mode, and the irradiation means The energy per unit area given to the droplet is different between the first printing mode and the second printing mode. The first ink set only needs to include at least the first ink composition, and may include only the first ink composition. The first ink set may further include an ink composition that is not included in the second ink set.

  Hereinafter, a preferred embodiment of a liquid ejection device will be described in detail with reference to the drawings. FIG. 1 is a perspective view schematically showing an ink jet printer 20 (hereinafter also simply referred to as “printer 20”) which is an embodiment of a droplet discharge device according to the present invention. FIG. 2 is a schematic diagram showing the back surface of the carriage 50 when the conveyance direction SS of the recording medium P is the front surface of the carriage 50. FIG. 3 is a schematic diagram illustrating the bottom surface of the carriage 50 when the conveyance direction SS of the recording medium P is the front surface of the carriage 50. As shown in FIG. 1, the printer 20 includes a head 52 and a first light source 90 as an irradiation unit.

1.1. Head The head 52 discharges the radiation curable ink composition into droplets having a minute particle diameter and ejects the droplets from the nozzle holes 53a to adhere onto the recording medium P. The head 52 is not particularly limited as long as it has the above function, and any recording method may be used. As a recording method of the head 52, for example, a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, ink is continuously ejected from the nozzle in the form of droplets, and the ink droplets are between the deflection electrodes. A method in which a print information signal is applied to the polarizing electrode during recording, or a method in which ink droplets are ejected in accordance with the print information signal without deflection (electrostatic suction method), and pressure is applied to the ink liquid using a small pump. , A method of forcibly ejecting ink droplets by mechanically vibrating the nozzle with a crystal resonator, etc., a method for simultaneously applying pressure and print information signals to the ink liquid with a piezoelectric element, and ejecting and recording ink droplets ( Piezo method), a method in which an ink liquid is heated and foamed with a microelectrode in accordance with a print information signal, and ink droplets are ejected and recorded (thermal jet method).

  The droplet discharge apparatus according to the present invention may be a serial type printer 20 in which a head 52 is mounted on a carriage 50 as shown in FIG. In the serial type printer 20, the head 52 moves in a predetermined direction as the carriage 50 moves in the predetermined direction MS. Further, when the platen 40 is operated by driving the motor 30, the recording medium P moves in the transport direction SS. Thereby, the radiation curable ink composition can be attached to different positions on the recording medium P.

  The head 52 is a serial head for full-color printing that ejects four colors of ink, and includes a nozzle row 53 corresponding to each color. The nozzle row 53 includes a large number of nozzle holes 53a. In addition to the head 52, the carriage 50 on which the head 52 is mounted contains a black cartridge 54 as a black ink container containing black ink supplied to the head 52, and color ink supplied to the head 52. A color ink cartridge 56 as color ink is mounted. The ink stored in each of the cartridges 54 and 56 is a radiation curable ink composition described later. The printer 20 according to the present embodiment includes the head 52 that ejects four colors of ink. However, the present invention is not limited to this, and it is only necessary to include a head that can eject ink of two or more colors. In addition, the printer 20 may replace the ink when selecting the print mode, and may include an ink set used in the print mode.

1.2. First Light Source The printer 20 according to this embodiment includes a first light source 90 as an irradiation unit. The first light source 90 irradiates actinic radiation to the droplets discharged and attached to the recording medium P by the head 52. In the example of FIGS. 1 to 3, the first light source 90 includes first light sources 90 </ b> A and 90 </ b> B provided at both ends of the head 52 in the predetermined direction MS. Specifically, as shown in FIG. 2, the first light source 90A is arranged on the right side of the head 52 (in the direction of arrow B in FIG. 2), and on the left side of the head 52 (in the direction of arrow C in FIG. 2) A first light source 90B is arranged. In the example of FIG. 1, one first light source is disposed on each side of one head, but two or more first light sources may be disposed on both sides of one head.

  The shape of the first light source 90 is not particularly limited, but the active radiation is applied to the droplets of the radiation curable ink composition ejected from the nozzle holes 53a of the head 52 and landed on the recording medium P by one movement of the carriage 50. Preferably, the shape can be irradiated. In the example of FIG. 3, the distance of the first light source 90 is formed to be longer than the distance of the nozzle row 53 in the transport direction SS of the recording medium P. If it forms so that actinic radiation can be irradiated, it will not specifically limit. In addition, the size (length) of the first light source 90 in the predetermined direction MS and the distance between the first light source 90 and the recording medium P are determined in consideration of the intensity of the active radiation to be irradiated, the irradiation period, and the like. It can be set arbitrarily.

  The first light source 90 irradiates the active radiation to the droplets of the radiation curable ink composition that has landed on the recording medium P. The first light source 90 takes into consideration the moving speed of the carriage 50 and the distance to the recording medium P from the viewpoint that a good image can be formed, and from 0 ms to 500 ms after the droplets land on the recording medium P. It is preferable to arrange the actinic radiation from the first light source 90 at a position where the droplet is irradiated within the period of time.

  As the 1st light source 90, it is preferable to use either LED (Light Emitting Diode) or LD (Laser Diode). Thereby, compared with the case where a mercury lamp lamp, a metal halide lamp, and other lamps are used, it is possible to avoid an increase in the size of the first light source 90 due to equipment such as a filter. Further, the intensity of the active radiation emitted by absorption by the filter does not decrease, and the radiation curable ink composition can be efficiently cured.

  Further, the emitted wavelength may be the same or different for each light source of the first light source 90 (for each of the first light sources 90A and 90B). When using LED or LD as a light source, the wavelength of the emitted active radiation should just be in the range of about 350-430 nm.

  In the example of FIG. 3, the first light source 90 has a configuration in which a plurality of ultraviolet light emitting diodes (ultraviolet LEDs) (symbol D) are arranged.

  Note that the printer 20 according to the present embodiment includes first light sources 90 on both sides of a predetermined direction MS of the head 52 in order to perform so-called bidirectional printing. On the other hand, if so-called unidirectional printing is performed in which the carriage moves only in one direction during printing, the first light source 90 need only be provided on one direction side (the carriage movement direction side) with respect to the head. . In any case, it is preferable that the position of the first light source 90 is adjusted so that the first light source 90 irradiates the droplet within 500 ms after the landing of the droplet. Note that the irradiation by the first light source 90 performed within 500 ms after the landing of the droplet is preferably completed within 500 ms.

1.3. Other Configurations The printer 20 according to the present embodiment can include the following configurations.

  The printer 20 according to the present embodiment may include a second light source (not shown). The second light source can further cure the droplets attached to the recording medium. The second light source may be mounted on the carriage 50 and provided closer to the recording medium P in the transport direction SS than the head 52. The second light source may be mounted on the carriage and disposed at a position opposite to the head 52 with respect to the first light source 90. Further, the second light source may be fixed on the transport direction SS side of the recording medium P without being mounted on the carriage 50. As described above, the installation position of the second light source is not particularly limited as long as the second light source is provided at a position where the droplet irradiated with the active radiation by the first light source 90 can be irradiated with the active radiation again.

  For the same reason as the first light source 90, the second light source is preferably an LED or an LD. When using LED or LD as a light source, the wavelength of the emitted active radiation should just be in the range of about 350-430 nm. Moreover, when it has two or more 2nd light sources, the wavelength radiate | emitted for every light source may be the same, and may differ.

  The printer 20 shown in FIG. 1 includes a motor 30 that sends the recording medium P in the transport direction SS, a platen 40, a carriage 50, and a carriage motor 60 that moves the carriage 50 in a predetermined direction MS. .

  The carriage 50 is pulled by a pulling belt 62 driven by a carriage motor 60 and moves along a guide rail 64.

  In the printer 20 shown in FIG. 1, a capping device 80 is provided at the home position of the carriage 50 (the position on the right side in FIG. 1) for sealing the surface of the head 52 where the nozzle holes 53a are formed when stopped. It has been. When the print job ends and the carriage 50 reaches above the capping device 80, the capping device 80 is automatically raised by a mechanism (not shown) to seal the surface of the head 52 where the nozzle holes 53a are formed. it can.

  The printer 20 illustrated in FIG. 1 includes a control unit 70. The control means 70 is configured using, for example, a computer having a CPU and a memory. The control means 70 executes various commands to move the carriage 50, eject the head 52, set the intensity and irradiation time of the active radiation of the first light source 90, and send the recording medium P in the transport direction SS. It is possible to perform such operation control.

  The control means 70 can have command information receiving means for receiving command information. The command information is output based on the operation of the operation accepting means by the user (for example, a touch panel and operation buttons provided on the printer 20, a keyboard such as a PC connected to the printer 20, etc.) and accepted by the command information accepting means. It is done. Examples of the command information include a first print mode execution command for executing a first print mode, which will be described later, and a second mode execution command for executing a second print mode. In addition, when executing the first printing mode, the control unit 70 performs control so that energy per unit area given to the droplets from the first light source is energy for the first printing mode. In addition, when executing the second printing mode, the control unit 70 performs control so that energy per unit area given to the droplets from the first light source is energy for the second printing mode. The energy can be controlled, for example, by changing the irradiation intensity of the first light source or changing the irradiation time of irradiation per unit area from the first light source.

  In addition, the control unit 70 can include an instruction execution unit that receives the instruction information output from the instruction information reception unit and performs an execution operation. The command execution means can perform an execution operation for controlling or coordinating the execution timing of each operation of the carriage 50, the head 52, the first light source 90, the motor 30, and the like.

1.4. Print Mode The printer 20 according to the present embodiment can execute the first print mode and the second print mode based on a command from the control unit 70. The mode in the present invention refers to a mode for forming a desired image on a recording medium using a droplet discharge device.

1.4.1. First Embodiment The first embodiment uses a monochrome print mode as the first print mode and a color print mode as the second print mode. Hereinafter, each print mode will be described in detail.

(1) Monochrome printing mode The monochrome printing mode is a mode for performing so-called monochrome printing using a black ink composition containing a black color material. In the monochrome printing mode, a black ink composition is used.

  The monochrome printing mode is executed as follows, for example. First, a monochrome print mode execution command is output by the operation of the operation receiving means by the user. The monochrome printing mode execution command is received by the command information receiving unit. Thereafter, the monochrome print mode execution command received by the command information receiving unit is output and received by the command execution unit. The command execution means performs an operation of selecting a black ink composition based on the monochrome print mode execution command and forming a monochrome image made of the black ink composition on the recording medium.

  Hereinafter, formation of an image on a recording medium in the monochrome printing mode will be described with reference to FIG. First, a black ink composition is ejected from the head 52 while moving the carriage 50 in the C direction, and a plurality of droplets are attached to the recording medium P. As a result of movement of the carriage 50 in the C direction (predetermined direction MS), the first actinic radiation is collectively irradiated by the first light source 90A to the plurality of droplets attached to the recording medium P. When the carriage 50 is moved in the B direction, the first actinic radiation is irradiated by the first light source 90B adjacent to the C direction side of each head 52.

  In this way, a monochrome image composed of the black ink composition is formed in a predetermined area of the recording medium P by repeating the operation from the adhesion of the droplet to the recording medium P to the irradiation of the active radiation to the droplet at least once. can do.

  Note that the number of times of irradiation of the active radiation applied to the droplets attached to the recording medium P by the first light source 90A is not particularly limited as long as it is one or more times. In addition, after the operation from the attachment of the droplet to the recording medium P to the irradiation of the active radiation to the droplet is performed once, an image is formed on the recording medium P by moving the recording medium P in the transport direction SS. May be. Alternatively, after performing a plurality of operations from attachment of the droplet to the recording medium P to irradiation of the active radiation to the droplet, an image is formed on the recording medium by moving the recording medium P in the transport direction SS. May be.

  Further, when the recording medium P is moved in the transport direction SS, the droplets attached to the recording medium P from the second light source provided on the transport direction SS side with respect to the head 52 may be further irradiated with actinic radiation. Good. Thereby, the droplets adhering to the recording medium P can be further cured.

(2) Color printing mode The color printing mode is an aspect for performing so-called color printing using the black ink composition used in the monochrome printing mode and the color ink composition containing a color material. It is. In the color printing mode, an ink set including a black ink composition and at least one color ink composition is used. Note that the color ink composition used in the color printing mode is not used in the monochrome printing mode described above.

  The color printing mode is different from the first mode in that two or more types of radiation-curable ink composition droplets are ejected from the head and the energy per unit area given to the droplets by the irradiation unit. Hereinafter, the difference between the color printing mode and the monochrome printing mode will be specifically described.

  In the color printing mode, two or more types of radiation curable ink compositions are ejected from the head. Therefore, two or more types of radiation curable ink composition droplets adhere to the recording medium P. Here, the radiation curable ink composition has different energy required for curing depending on the contained material and composition ratio. Therefore, when forming an image using two or more types of radiation curable ink compositions, it may be difficult to set irradiation conditions that give optimum energy for each type of radiation curable ink composition. is there. Therefore, in the case of forming an image using two or more types of radiation curable ink compositions, the irradiation conditions are preferable for all of the plurality of radiation curable ink compositions deposited on the recording medium. Set to On the other hand, since only one type of radiation curable ink composition (black ink composition) is used in the monochrome printing mode, irradiation conditions that give optimum energy to the radiation curable ink composition to be used (black ink composition portion) are used. Can be set. The irradiation conditions are set by adjusting the irradiation intensity and irradiation time applied to the droplets attached to the recording medium, the distance between the droplets attached to the recording medium and the irradiation means, and the like.

  Thus, the energy per unit area given to the droplets by the irradiation means is different between the monochrome printing mode and the color printing mode. Therefore, in the monochrome printing mode and the color printing mode, it is possible to set the optimum irradiation condition for each mode.

  Note that if the radiation curable ink composition contains a black color material, the black color material is likely to absorb energy. Therefore, the radiation curable ink composition containing a black color material tends to have a larger energy required for curing as compared with the case where another color material is contained. Therefore, it is more preferable that the energy per unit area given to the droplets in the monochrome printing mode is larger than the energy per unit area given to the droplets in the color printing mode. Accordingly, it is possible to efficiently cure the droplets attached to the recording medium P in the monochrome printing mode.

1.4.2. Second Embodiment In the second embodiment, the first color printing mode is used as the first printing mode, and the second color printing mode is used as the second printing mode. Hereinafter, each print mode will be described in detail.

(1) First Color Printing Mode The first color printing mode in the second embodiment is a so-called color that uses at least one color ink composition (first color ink composition) containing a color material. It is an aspect for performing printing. In the first color printing mode, an ink set including at least one color ink composition is used. In the first color printing mode in the second embodiment, a black ink composition may be used as in the color printing mode described in the first embodiment.

  Since the first color printing mode in the second embodiment is the same as the color printing mode in the first embodiment, the description thereof is omitted.

(2) Second Color Printing Mode Next, a light color printing mode that is an embodiment of the second color printing mode will be described. The light color printing mode includes a color ink composition (first color ink composition) used in the first color printing mode and a light color ink composition containing a light color coloring material not used in the first color printing mode ( This is an embodiment for performing so-called light color printing using the second color ink composition). In the light color printing mode, an ink set including at least one color ink composition and at least one light color ink composition is used.

  The second color ink composition may be an ink composition different from the first color ink composition. In addition to the light color ink composition, a special color ink composition such as red, orange, green, white, etc. Or an achromatic ink composition such as clear ink. Further, the second color printing mode may be a color printing mode other than the light color printing mode.

  In the present invention, the light color ink composition refers to an ink composition having a smaller color material content than a color ink composition using the same color material. As described above, since the light color ink composition has a smaller color material content than the color ink composition, the energy required for curing tends to be less than that of the color ink composition. Therefore, it is preferable that the energy per unit area given to the droplets in the light color printing mode is smaller than the energy per unit area given to the droplets in the color printing mode. Thereby, in the light color printing mode, it is possible to efficiently cure the droplets attached to the recording medium P.

  Except for the above, the light color printing mode is the same as the first color printing mode, and a description thereof will be omitted.

1.4.3. Others The comparison of the energy per unit area given to the droplets by the irradiation unit in the first printing mode and the second printing mode may be based on the energy given to the droplets until all irradiation by the irradiation unit is completed. Then, the energy given to the droplets by the irradiation means by a preset time may be used as a reference. The properties of the actinic radiation curable ink composition droplets tend to be determined by the energy per unit area given within 500 ms after adhering to the recording medium P. Therefore, the comparison of the energy per unit area given to the droplets by the irradiation unit in the monochrome printing mode and the color printing mode is based on the energy per unit area given to the droplets within 500 ms after adhering to the recording medium P. It is preferable to do.

  In each printing mode, it is preferable that the droplets are irradiated with actinic radiation within 500 ms after adhering to the recording medium P. As a result, a part of the radiation curable ink composition constituting the droplet is cured, spreads more than necessary on the recording medium P, and mixes with other droplets more than necessary. An image with good gloss, high color density, and reduced bleeding can be formed on the recording medium P. On the other hand, when the actinic radiation is irradiated for the first time after the droplet has adhered to the recording medium and has exceeded 500 ms, the droplet is cured in a state where the droplet is too wet and spread on the recording medium. . As a result, blurring or an image with reduced color density may be formed on the recording medium P.

Further, in the first printing mode, energy per unit area given to the droplets with respect to energy per unit area [E ₉₀ (mJ / cm ² )] for curing 90% of the ink composition provided in the first ink set. In the ratio [E1 (mJ / cm ² )] [E1 / E ₉₀ (%)] (hereinafter also referred to as “ratio A”) and in the second printing mode, the ink composition provided in the second ink set Ratio [E1 / E ₉₀ (%) of energy [E1 (mJ / cm ² )] per unit area given to the droplets relative to energy [E ₉₀ (mJ / cm ² )] per unit area to be 90% cured )] (Hereinafter also referred to as “ratio B”) is preferably within 30% (0% to 30%), and within 20% (0% to 20%). Particularly preferred. When the difference between the ratio A and the ratio B is within the above range, an image having excellent gloss and high color density can be formed on a recording medium regardless of which printing mode is used.

  Note that the difference between the ratio A and the ratio B is that the ratio A and the ratio B among the ratio A and the ratio B, and the ratio A and the ratio A when the plural types of ink compositions are used in each printing mode. The difference between the ink compositions including the difference B is the largest difference between them.

In each printing mode, the energy per unit area given to the droplets is 30% or more of the energy per unit area [E ₉₀ (mJ / cm ² )] for curing the radiation curable ink composition by 90% 60 % Or less, more preferably 40% or more and 60% or less, and particularly preferably 40% or more and 50% or less. Thereby, an image having excellent gloss and high color density can be formed on the recording medium.

The energy per unit area [mJ / cm ² ] given to the droplet in the present invention is, for example, the irradiation intensity [mW / cm ² ] per unit area on the surface of the droplet discharged onto the recording medium P and the irradiation. It can be obtained from the product of the duration [s]. The irradiation intensity can be measured with an ultraviolet intensity meter or the like.

Further, the energy per unit area (E ₉₀ ) [mJ / cm ² ] for curing the radiation curable ink composition in the present invention by 90% is the conversion rate of the polymerizable compound in the radiation curable ink composition is 90. This is the energy required to make a percentage. When the conversion ratio of the polymerizable compound contained in the radiation curable ink composition is 90% or more, the radiation curable ink composition is sufficiently cured and forms a good image with excellent abrasion resistance on the recording medium. can do. The conversion can be determined from the change in absorbance at the peak of a specific absorption spectrum using FT-IR (Fourier transform infrared spectrophotometer).

1.5. Radiation curable ink composition In this embodiment, the printer 20 can eject a plurality of radiation curable ink compositions. Hereinafter, the radiation curable ink composition that can be used in the printer 20 according to the present embodiment will be described in detail.

1.5.1. Polymerizable Compound The radiation curable ink composition according to this embodiment contains a polymerizable compound. Examples of the polymerizable compound include monofunctional monomers, bifunctional monomers, trifunctional monomers, urethane acrylate oligomers, and amino acrylates shown below.

  The monofunctional monomer is not particularly limited. For example, (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl (meth) acrylate, (2-methyl-2-isobutyl-1,3- Dioxolan-4-yl) methyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, methoxydiethylene glycol mono (meth) acrylate, (meth) acryloylmorpholine, dicyclopentenyloxyethyl (meth) acrylate, di Cyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, isobornyl (meth) acrylate, trimethylolpropane formal mono (meth) acrylate, adamantyl (meth) acrylate, oxetane (meth) acrylate Over DOO, 3,3,5-trimethylcyclohexane (meth) acrylate. These polymerizable compounds can be used alone or in combination of two or more. In this specification, the description of (meth) acrylate indicates acrylate or methacrylate.

  The bifunctional monomer is not particularly limited, and examples thereof include alkylene glycol di (meth) acrylate and di (meth) acrylate having an alicyclic structure. Examples of the alkylene glycol di (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and 1,9-nonanediol. Di (meth) acrylate, polyethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2-hydroxy-1, Examples include 3-di (meth) acryloxypropane. Examples of the di (meth) acrylate having an alicyclic structure include tricyclodecane dimethanol di (meth) acrylate, dioxane glycol di (meth) acrylate, isocyanuric acid EO-modified di (meth) acrylate, and dimethylol tricyclo. Examples include decanedi (meth) acrylate and 1,3-adamantanediol di (meth) acrylate. These polymerizable compounds can be used alone or in combination of two or more.

  The trifunctional monomer is not particularly limited. For example, trimethylolpropane tri (meth) acrylate, trimethylolpropane EO-modified tri (meth) acrylate, trimethylolpropane PO-modified tri (meth) acrylate, and glycerin PO-modified tri (meth). Examples thereof include acrylate and isocyanuric acid EO-modified tri (meth) acrylate.

  Moreover, as another polymeric compound, the N-vinyl compound may be included. Examples of the N-vinyl compound include N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, and derivatives thereof.

  Moreover, the urethane type oligomer may be included as a polymeric compound. The urethane-based oligomer means one having at least one urethane bond and radically polymerizable unsaturated double bond in the molecule. Here, the oligomer used in this embodiment is a small number of units substantially or conceptually obtained from a molecule having a small relative molecular mass (synonymous with molecular weight), generally about 2 to 20 times. Molecules with a medium relative molecular mass with a repetitive structure of about twice.

  Examples of the urethane oligomer include oligomers produced by an addition reaction between a polyol and a polyisocyanate and a polyhydroxy compound. Examples of urethane oligomers include polyester urethane acrylate, polyether urethane acrylate, polybutadiene urethane acrylate, and polyol urethane acrylate. Specifically, examples of the urethane oligomer include CN963J75, CN964, CN965, CN966J75 (all available from SARTOMER).

  Moreover, amino acrylate may be included as a polymeric compound. As aminoacrylate, what is obtained by making bifunctional (meth) acrylate and an amine compound react is mentioned.

  Examples of the bifunctional acrylate include propylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexanediol di (meth). Acrylate, 1,9-nonanediol di (meth) acrylate, alkylene glycol di (meth) acrylate such as neopentyl glycol di (meth) acrylate, di (meth) acrylate of bisphenol S ethylene oxide adduct, ethylene of bisphenol F Di (meth) acrylate of oxide adduct, di (meth) acrylate of ethylene oxide adduct of bisphenol A, di (meth) acrylate of ethylene oxide adduct of thiobisphenol, ethylene of brominated bisphenol A Bisphenol alkylene oxide adduct di (meth) acrylate such as di (meth) acrylate of oxide adduct, polyalkylene glycol di (meth) acrylate such as polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, hydroxypivalin Examples include di (meth) acrylate of acid neopentyl glycol ester.

  Examples of amine compounds include ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, n-pentylamine, isopentylamine, n-hexylamine, cyclohexylamine, n-heptylamine, and n-octylamine. Monofunctional amine compounds such as 2-ethylhexylamine, n-nonylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, benzylamine, phenethylamine, diethylenetriamine, triethylene Ethylenetetramine, tetraethylenepentamine, 1,6-hexamethylenediamine, 1,8-octamethylenediamine, 1,12-dodecamethylenediamine, o-phenylenediamine, p-phenylenediamine , M-phenylenediamine, o-xylylenediamine, p-xylylenediamine, m-xylylenediamine, menthanediamine, bis (4-amino-3-methylcyclohexylnomethane, 1,3-diaminocyclohexane, isophoronediamine And polyfunctional amine compounds such as spiroacetal-based diamines, and also high molecular weight type polyfunctional amine compounds such as polyethyleneimine, polyvinylamine, and polyallylamine.

  The content of the polymerizable compound is preferably 20% by mass or more, and more preferably 20% by mass or more and 95% by mass or less with respect to the total mass of the radiation curable ink composition.

1.5.2. Photopolymerization initiator The radiation curable ink composition according to the present embodiment may contain a photopolymerization initiator. The photopolymerization initiator is a general term for compounds having a function of initiating a copolymerization reaction of the above-described reaction components by irradiating the radiation curable ink composition discharged onto the recording medium with actinic radiation.

  Examples of the photopolymerization initiator include known photopolymerization initiators such as alkylphenone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, titanocene photopolymerization initiators, and thioxanthone photopolymerization initiators. It is done. Among these, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide having excellent compatibility with the above-mentioned reaction components, bis (2,4,6-trimethylbenzoyl) -phenylphosphine having a wide range of light absorption characteristics A molecular cleavage type such as fin oxide and a hydrogen abstraction type such as diethylthioxanthone are preferred. The reason why acylphosphine oxide-based photopolymerization initiators are preferable is that the structure of the chromophore changes greatly before and after photocleavage, so the change in absorption is large, and a short wavelength of absorption called photobleaching (photobleaching) is observed. Because it is. Moreover, it is because yellowing hardly occurs despite the absorption ranging from the UV to the VL region, and is excellent in internal curing. For this reason, it is particularly preferable for a transparent thick film or a pigmented coating film having a large hiding power. The reason why the thioxanthone photopolymerization initiator is preferable is that it reacts with oxygen remaining in the reaction system after photocleavage to lower the concentration of oxygen in the system. Since the degree of radical polymerization inhibition can be reduced as much as the oxygen concentration decreases, the surface curability can be improved. Further, it is particularly preferable to use an acyl phosphonic photopolymerization initiator and a thioxanthone photopolymerization initiator in combination. These photopolymerization initiators can be used singly or in combination of two or more, and each characteristic can be maximized.

  The content of the photopolymerization initiator is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 15% by mass or less with respect to the total mass of the radiation curable ink composition.

1.5.3. Other Additives The radiation curable ink composition according to the present embodiment can contain additives such as pigments, dispersants, slip agents, photosensitizers, polymerization inhibitors, and the like as necessary.

  The radiation curable ink composition according to this embodiment can function as a so-called clear ink as it is, but may further contain a pigment. Although it does not restrict | limit especially as a pigment which can be used in this embodiment, An inorganic pigment and an organic pigment are mentioned. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. On the other hand, organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinofullerone pigments, etc.) Nitro pigments, nitroso pigments, aniline black, and the like can be used.

  Among specific examples of pigments that can be used in the present embodiment, carbon black includes C.I. I. Pigment black 7, for example, No. available from Mitsubishi Chemical Corporation. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. Raven5750, 5250, 5000, 3500, 1255, 700, etc. available from Columbia Chemical Company 2200B, etc. Also, Regal400R, 330R, 660R, MoguL, available from Cabot 700, Monarch 800, 880, 900, 1000, 1100, 1300, 1400, etc. Also available from Degussa are ColorBlack FW1, FW2, FW2V, FW18, FW200, ColorBlackS150, S160. , S170, Printex35, U, V, 140U, Special Black6, 5, 4A, 4 and the like.

  Examples of pigments that can be used when the radiation curable ink composition according to this embodiment is a yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 180, 185, 213 and the like.

  Examples of pigments that can be used when the radiation curable ink composition according to the present embodiment is magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, 209, C.I. I. Pigment violet 19 and the like.

  Examples of pigments that can be used when the radiation curable ink composition according to the present embodiment is cyan ink include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15: 4, 16, 22, 60, and the like.

  Examples of pigments that can be used when the radiation curable ink composition according to this embodiment is a green ink include C.I. I. Pigment green 7, 8, 36, and the like.

  Examples of pigments that can be used when the radiation curable ink composition according to this embodiment is an orange ink include C.I. I. Pigment orange 51, 66 and the like.

  Examples of pigments that can be used when the radiation curable ink composition according to the present embodiment is white ink include basic lead carbonate, zinc oxide, titanium oxide, and strontium titanate.

  The average particle diameter of the pigment that can be used in the present embodiment is preferably in the range of 10 nm to 200 nm, more preferably in the range of 50 nm to 150 nm.

  The amount of the pigment that can be added to the radiation curable ink composition according to the present embodiment is 0.1% by mass or more and 25% by mass or less, more preferably, based on the total mass of the radiation curable ink composition. It is 0.4 mass% or more and 15 mass% or less.

  In the radiation curable ink composition according to this embodiment, a dispersant may be added for the purpose of improving the dispersibility of the pigment. Dispersants that can be used in the present embodiment include Solsperse 3000, 5000, 9000, 12000, 13240, 17000, 24000, 26000, 28000, 36000 (above, manufactured by Lubrizol), DISCOL N-503, N-506. , N-509, N-512, N-515, N-518, N-520 (above, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and the like.

  A slip agent may be added to the radiation curable ink composition according to this embodiment. The slip agent that can be used in the present embodiment is preferably a silicone-based surfactant, more preferably a polyester-modified silicone or a polyether-modified silicone. Specifically, examples of the polyester-modified silicone include BYK-347, 348, BYK-UV3500, 3510, 3530 (above, manufactured by BYK Chemie Japan Co., Ltd.), and the polyether-modified silicone includes BYK. -3570 (made by Big Chemie Japan Co., Ltd.) and the like.

  A photosensitizer may be added to the radiation curable ink composition according to this embodiment. Photosensitizers that can be used in this embodiment include amine compounds (aliphatic amines, amines containing aromatic groups, piperidine, reaction products of epoxy resins and amines, triethanolamine triacrylate, etc.), urea compounds ( Allylthiourea, o-tolylthiourea, etc.), sulfur compounds (sodium diethyldithiophosphate, soluble salts of aromatic sulfinic acid, etc.), nitrile compounds (N, N-diethyl-p-aminobenzonitrile, etc.), phosphorus compounds (tri -N-butylphosphine, sodium diethyldithiophosphide, etc.), nitrogen compounds (Michler ketone, N-nitrisohydroxylamine derivative, oxazolidine compound, tetrahydro-1,3-oxazine compound, formaldehyde or acetaldehyde and diamine condensate, etc. , Chlorine compounds (carbon tetrachloride, hexachloroethane, etc.) and the like.

  A polymerization inhibitor may be added to the radiation curable ink composition according to this embodiment. Examples of the polymerization inhibitor that can be used in this embodiment include hydroquinone, benzoquinone, and p-methoxyphenol.

1.5.4. Physical Properties (1) Viscosity The viscosity at 20 ° C. of the radiation curable ink composition according to this embodiment is preferably 5 mPa · s to 50 mPa · s, and more preferably 20 mPa · s to 40 mPa · s. When the viscosity at 20 ° C. of the radiation curable ink composition is within the above range, an appropriate amount of the radiation curable ink composition is ejected from the nozzle, and the flight bending and scattering of the radiation curable ink composition can be further reduced. Therefore, it can be suitably used for an ink jet recording apparatus. The viscosity was measured by using a viscoelasticity tester MCR-300 (manufactured by Pysica), increasing the Shear Rate to 10 to 1000 in an environment of 20 ° C., and reading the viscosity at Shear Rate 200.

(2) Surface Tension The surface tension at 20 ° C. of the radiation curable ink composition according to this embodiment is preferably 20 mN / m or more and 30 mN / m or less. When the surface tension at 20 ° C. of the radiation curable ink composition is within the above range, the radiation curable ink composition is hardly wetted by the liquid-repellent treated nozzle. Accordingly, an appropriate amount of the radiation curable ink composition is ejected from the nozzle, and the flight bending and scattering of the radiation curable ink composition can be further reduced, so that it can be suitably used for an ink jet recording apparatus. The surface tension was measured by using an automatic surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) to confirm the surface tension when the platinum plate was wetted with ink in an environment of 20 ° C.

(3) Energy per unit area for curing 90% of the radiation curable ink composition (E ₉₀ )
The E ₉₀ (mJ / cm ² ) of the radiation curable ink composition according to this embodiment is preferably 120 mJ / cm ² or more and 300 mJ / cm ² or less. When E ₉₀ of the radiation curable ink composition is within the above range, it becomes easy to use the printer 20 described above. It should be noted that the measurement of E ₉₀ can be done using a FT-IR (Thermo Fisher Scientific Co., Ltd., product name "MAGNA-IR 860 Nicolet").

1.6. Recording medium The recording medium used in the printer 20 according to the present embodiment is preferably non-ink-absorbing or low-absorbing. When the printer 20 of the present embodiment is used, a good image can be formed even if the recording medium is non-ink-absorbing or low-absorbing.

As a non-ink-absorbing recording medium, for example, a plastic film coated on a substrate such as a plastic film or paper that has not been surface-treated for inkjet printing (that is, an ink-absorbing layer is not formed). And those having a plastic film adhered thereto. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. Examples of the recording medium having low ink absorption include printing paper such as art paper, coated paper, and matte paper. Here, in this specification, “ink non-absorbing or low-absorbing recording medium” means “the amount of water absorption from the start of contact to 30 msec ^1/2 in the Bristow method is 10 mL / m ² or less. Recording medium ". This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method". In the present specification, a non-ink-absorbing or low-absorbing recording medium is also referred to as “plastic medium”.

2. EXAMPLES Hereinafter, the present invention will be specifically described with reference to the following examples, but the present invention is not limited thereto.

2.1. Preparation of pigment dispersion 18 parts by weight of black pigment (made by Ciba Specialty Chemicals, trade name “MICROLITH-WA Black C-WA”) as a color material, 1.2 parts by weight of Solsperse 36000 (manufactured by LUBRIZOL) as a dispersant Was added with phenoxyethyl acrylate (Osaka Organic Chemical Co., Ltd., trade name “V # 192”) as a monofunctional monomer to make 100 parts by mass, and the mixture was stirred to obtain a mixture. This mixture was subjected to a dispersion treatment for 6 hours together with zirconia beads (diameter 1.5 mm) using a sand mill (manufactured by Yaskawa Seisakusho Co., Ltd.). Then, the black pigment dispersion liquid was obtained by isolate | separating a zirconia bead with a separator. Similarly to the black pigment dispersion, a yellow pigment dispersion, a cyan pigment dispersion, a magenta pigment dispersion, a light cyan pigment dispersion, and a light magenta pigment dispersion were prepared.

2.2. Preparation of radiation curable ink composition A polymerizable compound, a photopolymerization initiator, a slip agent, and a polymerization inhibitor were mixed and completely dissolved so that the composition (mass%) shown in Table 1 was obtained. The black pigment dispersion was added dropwise with stirring so that the concentration of the black pigment was as shown in Table 1. After completion of the dropwise addition, the mixture was stirred for 1 hour at room temperature, and further filtered through a 5 μm membrane filter to obtain a black radiation curable ink composition. Similarly to the black radiation curable ink composition, the yellow radiation curable ink composition, the cyan radiation curable ink composition, the magenta radiation curable ink composition, the light cyan radiation curable ink composition, and the light magenta radiation curable. A mold ink composition was prepared.

The components used in Table 1 are as follows.
(1) Polymerizable compound / phenoxyacrylate (Osaka Organic Chemical Industry Co., Ltd., trade name “V # 192”)
・ Dicyclopentenyloxyethyl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name “FA512AS”)
・ Dicyclopentenyl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name “FA511AS”)
・ N-Vinylcaprolactam (trade name “N-Vinylcaprolactam” manufactured by BASF)
Amino acrylate (Daicel Cytec Co., Ltd., trade name “EBECRYL 7100”)
・ Tripropylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “APG-200”)
・ Dipropylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “APG-100”)
(2) Polymerization inhibitor, p-methoxyphenol (manufactured by Kanto Chemical Co., Inc.)
(3) Slip agent BYK-UV3500 (by Big Chemie Japan Co., Ltd., polydimethylsiloxane having a polyether-modified acrylic group)
(4) Photopolymerization initiator IRGACURE 819 (Ciba Japan Co., Ltd., bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, photopolymerization initiator)
DAROCUR TPO (Ciba Japan Co., Ltd., 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, photopolymerization initiator)
・ DETX (Nippon Kayaku Co., Ltd., photopolymerization initiator)
(5) Dispersant: Solsperse 36000 (manufactured by LUBRIZOL)
(6) Pigment / MICROLITH-WA Black C-WA (manufactured by Ciba Specialty Chemicals Co., Ltd., black pigment)
・ IRGALITE BLUE GLVO (Ciba Specialty Chemicals, Cyan Pigment)
・ CROMOPHTAL PinkPT (SA) GLVO Ciba Specialty Chemicals Co., Ltd., magenta pigment ・ IRGALITE YELLOW LBG Ciba Specialty Chemicals Co., Ltd., yellow pigment

2.3. Measurement of E ₉₀ of radiation curable ink composition Energy per unit area (E ₉₀ ) [mJ / cm ² ] for curing the radiation curable ink composition by 90% is FT-IR (Thermo Fisher Scientific Co., Ltd.) Product name “MAGNA-IR 860 Nicolet”) from the absorption spectrum peak (810 cm ⁻¹ ) of the vinyl group in each radiation-curable ink composition before and after irradiation with actinic radiation.

Specifically, first, the peak height A ₀ before irradiation of 810 cm ^-1, seek, and peak height A _t of 810 cm ^-1 after irradiation from the IR spectrum, using the following equation (1) curing The rate was calculated.

Curing rate (%) = 100 × (1−A _t / A ₀ ) (1)
As a result, energy (E ₉₀ ) [mJ / cm ² ] per unit area required for the radiation curable ink composition to have a curing rate of 90% was determined. Table 1 shows the E ₉₀ values of the obtained radiation curable ink compositions.

In addition, the measurement of energy per unit area given to the radiation curable ink composition is the distance from the UV-LED (the same as that used in the preparation of the evaluation sample described later) to the radiation curable ink composition, The measurement was performed with the same distance from the first light source 90 (UV-LED) used in the preparation of the evaluation sample described later to the recording medium. The radiation-curable ink composition was irradiated with the UV-LED having an active peak wavelength of 395 nm, and the energy per unit area given to the radiation-curable ink composition was measured. The energy [mJ / cm ² ] per unit area given to the radiation curable ink composition is the irradiation intensity [mW / cm ² ] per unit area on the surface of the droplets ejected to the recording medium P and the irradiation continuation. It was obtained from the product of time [s]. The irradiation intensity was measured using an ultraviolet intensity meter UM-10 and a light receiving unit UM-400 (manufactured by Konica Minolta Sensing Co., Ltd.).

2.4. Inkjet printer An inkjet printer PX-G5000 (manufactured by Seiko Epson Corporation) was modified to have the same configuration as the printer 20 of FIG. Specifically, the head 52 was modified so as to have the first light sources 90A and 90B provided on both sides in the predetermined direction MS. The cartridge 54 contains the black radiation curable ink composition, and the color ink cartridge 56 contains the cyan radiation curable ink composition, the magenta radiation curable ink composition, and the yellow radiation curable ink. A composition, a light cyan ink radiation curable ink composition, and a light magenta radiation curable ink composition were accommodated. Moreover, UV-LED was used for the 1st light source 90 (90A and 90B), and it was made possible to irradiate the droplet of a radiation curable ink composition with 395 nm ultraviolet rays.

2.5. Preparation of evaluation sample 2.5.1. Example 1
From head 52, cyan radiation curable ink composition (C), magenta radiation curable ink composition (M), yellow radiation curable ink composition (Y), black radiation curable ink composition (K), light cyan radiation curable. The ink droplets of the ink composition (Lc) and the light magenta radiation curable ink composition (Lm) were ejected onto the PET film, and then the ultraviolet rays were irradiated from the first light source 90 to the droplets. The PET film was moved in the transport direction SS. By repeating such an operation a plurality of times, an image in which each color of C, M, Y, K, Lc, and Lm was recorded on the PET film was obtained. Then, the image was completely cured by irradiating ultraviolet rays so that the energy per unit area finally given to the droplets forming the recorded image was E ₉₀ or more. In this way, an evaluation sample according to Example 1 was created.

  The printing conditions were a resolution of 720 × 720 dpi and a droplet amount of 14 pl. The droplets were irradiated with the first ultraviolet rays 50 ms after adhering to the PET film. Further, the energy per unit area initially given to the droplet is assumed to be E1.

2.5.2. Example 2
In the preparation of the evaluation sample according to Example 2, the irradiation conditions are set so that the energy (E1) per unit area given to the droplet within 500 ms is smaller than that of “2.5.1. Example 1”. It was adjusted. Other than this, an evaluation sample according to Example 2 was created in the same manner as in “2.5.1. Example 1” above.

2.5.3. Example 3
In the preparation of the evaluation sample according to Example 3, the irradiation conditions are set so that the energy (E1) per unit area given to the droplet within 500 ms is smaller than that of “2.5.1. Example 1”. It was adjusted. Other than this, an evaluation sample according to Example 3 was created in the same manner as in “2.5.1. Example 1” above.

2.5.4. Example 4
In the preparation of the evaluation sample according to Example 4, the irradiation conditions are set so that the energy per unit area (E1) given to the droplet within 500 ms is smaller than that of “2.5.1. Example 1”. It was adjusted. Other than this, an evaluation sample according to Example 4 was created in the same manner as in “2.5.1. Example 1” above.

2.5.5. Example 5
In the preparation of the evaluation sample according to Example 5, the irradiation conditions are set so that the energy (E1) per unit area given to the droplet within 500 ms is smaller than that of “2.5.1. Example 1”. It was adjusted. Other than this, an evaluation sample according to Example 5 was created in the same manner as in “2.5.1. Example 1” above.

2.5.6. Example 6
In the preparation of the evaluation sample according to Example 6, after the droplets of the black radiation curable ink composition (K) were ejected from the head 52 and deposited on the PET film, ultraviolet rays were applied to the droplets from the first light source 90. Irradiated to move the PET film in the transport direction SS. By repeating such an operation a plurality of times, a solid pattern image consisting only of the black radiation curable ink composition was formed on the PET film. Then, the solid pattern image was completely cured by irradiating the droplets forming the recorded solid pattern image with ultraviolet rays so that the energy per unit area finally given was E ₉₀ or more. In this way, an evaluation sample according to Example 1 was created.

  The printing conditions were a resolution of 720 × 720 dpi and a droplet amount of 14 pl. The droplets were irradiated with the first ultraviolet rays from the first light source 90 50 ms after adhering to the PET film.

2.5.7. Example 7
In the preparation of the evaluation sample according to Example 7, the irradiation conditions are adjusted so that the energy (E1) per unit area given to the droplet within 500 ms is larger than in “2.5.5.6 Example 6” above. did. Other than this, an evaluation sample according to Example 7 was created in the same manner as in “2.5. 6. Example 6” above.

2.5.8. Example 8
In the preparation of the evaluation sample according to Example 8, the irradiation conditions are adjusted so that the energy per unit area (E1) given to the droplet within 500 ms is larger than the above “2.5. 6. Example 6”. did. Other than this, an evaluation sample according to Example 8 was created in the same manner as in “2.5. 6. Example 6” above.

2.5.9. Example 9
In the preparation of the evaluation sample according to Example 9, the irradiation conditions are adjusted so that the energy (E1) per unit area given to the droplet within 500 ms is larger than in “2.5.5.6 Example 6” above. did. Other than this, an evaluation sample according to Example 9 was created in the same manner as in “2.5. 6. Example 6” above.

2.5.10. Example 10
Preparation of the evaluation sample according to Example 10 was performed in the same manner as “2.5. 7. Example 7” except that the time until the droplet was first irradiated with ultraviolet rays was 500 ms. In this way, an evaluation sample according to Example 10 was created.

2.5.11. Example 11
Preparation of the evaluation sample according to Example 11 was performed in the same manner as “2.5. 7. Example 7” except that the time until the droplet was first irradiated with ultraviolet rays was set to 800 ms. In this way, an evaluation sample according to Example 11 was created.

2.6. Evaluation test 2.6.1. Glossiness Evaluation Test Using the glossiness meter MULTI Gloss 268 (manufactured by Konica Minolta Co., Ltd.) based on JIS Z8741, the specular gloss at 60 degrees of the obtained image for the obtained evaluation samples of Examples 1 to 11 The degree was measured for each color. The evaluation criteria for the glossiness of the obtained image are as follows, and gloss is recognized by evaluation of B or higher.

A: Glossiness of 70 or more B: Glossiness of 50 or more and less than 70 C: Glossiness of 30 or more and less than 50 D: Glossiness of less than 30

2.6.2. Color Density Evaluation Test For the obtained evaluation samples of Examples 1 to 11, the optical density (OD value) was measured for each color using a colorimeter (product name: Spectrolino, manufactured by GretagMacbeth). The evaluation criteria of the obtained image are as follows. When the evaluation is “◎” and “◯” (OD value is 1.7 or more), an image having no problem in practical use is formed. I can judge.

A: OD value of 1.8 or more (high color density and good color development)
○: OD value 1.7 or more and less than 1.8 (color density is slightly low, but color developability is good)
Δ: OD value less than 1.7 (color density is low and color developability is poor)

2.6.3. Bleeding test The evaluation samples of Examples 1 to 11 obtained were evaluated by observing the blurring of the contour portion of the image for each color. The evaluation criteria are classified as follows. If the evaluation is “「 ”,“ ◯ ”, or“ Δ ”, it can be determined that an image having no problem in practical use is formed.
A: The outline of the sample is not blurred even by microscopic observation.
○: The sample outline does not bleed visually, but bleed is observed under a microscope.
Δ: Slight blurring can be visually confirmed on the outline of the sample.
X: Blur can be clearly confirmed visually on the outline of the sample.

2.7. Evaluation results The above evaluation results are shown in Tables 2 and 3.

  The evaluation result of the image created under the conditions of Example 1 showed that K ink can record a sufficiently good image under the conditions of Example 1. On the other hand, Y, C, M, Lc, and Lm inks recorded images with poor glossiness and color density. As described above, the condition according to Example 1 can be used as the monochrome print mode, but it is not preferable to use it in the color print mode and the light color print mode.

  From the evaluation results of the image created under the conditions of Example 2, it was shown that K, Y, C, and M inks can record a sufficiently good image under the conditions of Example 2. In particular, it was shown that K ink is most preferable to record an image under the conditions of Example 2. On the other hand, the Lc and Lm inks recorded images that were not excellent in gloss and color density. From the above, the condition of Example 2 can be particularly preferably applied to the monochrome printing mode.

  The evaluation results of the image created under the conditions of Example 3 showed that all the inks used were able to record a sufficiently good image under the conditions of Example 3. In particular, it was shown that Y, C, and M inks are most preferably recorded under the conditions of Example 2. From the above, the condition of Example 3 can be particularly suitably used for the color printing mode.

  The evaluation results of the image created under the conditions of Example 4 showed that all the inks used could record a sufficiently good image under the conditions of Example 4. In particular, it was shown that Lc and Lm inks are most preferable to record an image under the conditions of Example 4. From the above, the condition of Example 4 can be particularly suitably used for the light color printing mode.

  From the evaluation results of the image created under the conditions of Example 5, it was shown that C, M, Lc, and Lm inks can record a sufficiently good image under the conditions of Example 1. On the other hand, the images recorded with K and Y inks were slightly blurred. Thus, the conditions according to Example 5 can be suitably used as a light color printing mode that does not use Y ink.

  From the evaluation results of Examples 1 to 5 above, it was shown that an even better image can be formed by setting appropriate irradiation conditions for each printing mode.

  In any of the evaluation samples according to Examples 6 to 10, the time until the droplet was first irradiated with the active radiation was within 500 ms. Therefore, all of the evaluation samples according to Examples 6 to 10 had good glossiness and color density.

  On the other hand, in the evaluation sample according to Example 11, the first active irradiation beam was not irradiated to the droplet within 500 ms. Therefore, a slight blur occurred in the recorded image.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

  DESCRIPTION OF SYMBOLS 20 ... Inkjet printer, 30 ... Motor, 40 ... Platen, 50 ... Carriage, 52 ... Head, 53 ... Nozzle row, 53a ... Nozzle hole, 54 ... Black ink cartridge, 56 ... Color ink cartridge, 60 ... Carriage motor, 62 ... Towing belt, 64 ... guide rail, 70 ... control means, 80 ... capping device, 90 (90A, 90B) ... first light source.

Claims (8)

A head for ejecting droplets of a radiation curable ink composition to adhere to a recording medium;
An irradiation unit that irradiates the droplets attached to the recording medium with active radiation;
A first printing mode using at least the first radiation curable ink composition;
A second print mode using the first radiation curable ink composition and a second radiation curable ink composition that is not used in the first print mode;
Printing by selecting the first printing mode and the second printing mode;
The method for controlling a droplet discharge apparatus, wherein energy per unit area given to the droplets by the irradiation unit is different between the first printing mode and the second printing mode. In the control method of the droplet discharge device according to claim 1,
The first radiation curable ink composition is a black ink composition containing a black coloring material,
The second radiation curable ink composition is a color ink composition containing a color material,
The first printing mode is a monochrome printing mode using the black ink composition,
The method for controlling a droplet discharge device, wherein the second printing mode is a color printing mode using at least the black ink composition and the color ink composition. In the control method of the liquid discharging apparatus of Claim 1,
The first radiation curable ink composition is a first color ink composition containing a color material.
The second radiation curable ink composition is a second color ink composition different from the first color ink composition,
The first printing mode is a first color printing mode using a first color ink composition,
The method for controlling a droplet discharge device, wherein the second printing mode is a second color printing mode using at least the first color ink composition and the second color ink composition. In the control method of the droplet discharge device according to any one of claims 1 to 3,
In each of the first printing mode and the second printing mode, after the droplets of the radiation curable ink composition are attached to the recording medium, the droplets are collectively irradiated with actinic radiation. A method for controlling a droplet discharge device. In the control method of the droplet discharge device according to any one of claims 1 to 4,
A method for controlling a droplet discharge device, wherein the droplet is irradiated with the active radiation within 500 ms after adhering to the recording medium. A method for controlling a droplet discharge device according to any one of claims 1 to 5,
The energy per unit area [E1 (mJ / cm ² ) given to the droplets with respect to the energy per unit area [E ₉₀ (mJ / cm ² )] for curing 90% of the ink composition used in the first printing mode. ² )] ratio [E1 / E ₉₀ (%)] and
The energy per unit area [E1 (mJ / cm ² ) given to the droplets with respect to the energy per unit area [E ₉₀ (mJ / cm ² )] for curing the ink composition used in the second printing mode by 90%. ² )] in the ratio [E1 / E ₉₀ (%)] is within 30%. A droplet discharge device for use in the method of controlling a droplet discharge device according to any one of claims 1 to 6,
The head moves along a predetermined direction;
The irradiation unit is a droplet discharge device provided on at least one side of the head in the predetermined direction. An ink set comprising a first ink composition and a second ink composition for use in the method for controlling a droplet discharge device according to any one of claims 1 to 6,
Comprising a plurality of radiation curable ink compositions;
The ink set in which the energy per unit area for curing the radiation curable ink composition by 90% is the highest among the plurality of radiation curable ink compositions, which is the black ink composition containing a black colorant.

Images