JP2011207103A - Inkjet recording apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus capable of forming, on a non-absorbent recording medium by using a photo-curable ink composition, an image with preferable definition and glossiness and without excessive color mixture.SOLUTION: The inkjet recording apparatus 100 includes: a head 10; a first light source 21 disposed at least at one end of the head 10 in the scan direction, for light irradiation; a second light source 22 disposed at the end on the opposite side of the head 10 of the first light source 21, for light irradiation; and a third light source 23 disposed at the end on the opposite side of the first light source 21 of the second light source 22, for light irradiation.

Description

  The present invention relates to an ink jet recording apparatus and an image forming method.

  In recent years, development of photocurable ink compositions that are cured by ultraviolet rays, electron beams, or other light has been promoted. Such a photocurable ink composition is generally composed of a polymerizable compound, a polymerization initiator, a pigment and other additives. In general, when an image is formed using a photocurable ink composition, for example, after being deposited on a recording medium by an ink jet recording apparatus, by irradiating light using an appropriate light source, This is done by curing the composition.

  For example, Patent Document 1 discloses an image forming method for irradiating actinic ray curable ink with actinic rays by two or more irradiation means. In this publication, the degree of curing of the ink by the first actinic ray is set to 6 to 70%, and after all the printing is completed, a sufficient actinic ray is irradiated to completely cure, thereby forming a high-definition image. Is described.

JP 2004-216681 A

  By the way, the photocurable ink composition may be used for recording on a non-absorbing recording medium that does not absorb or hardly absorbs ink such as plastic, glass, and coated paper. In such recording, the photocurable ink composition does not penetrate into the recording medium and is adhered while the shape of the droplet is kept long. In the case where the attached droplets have fluidity, for example, they may merge with adjacent droplets to cause color mixing, or the droplets may get wet and spread, resulting in a reduction in image definition.

  Conversely, if the photocurable ink composition is made to adhere to a non-absorbent recording medium and then irradiated with sufficient light to increase the degree of curing, the fluidity of the droplets will be lost. Therefore, an image is formed with the shape of the droplet as it is attached. In this case, for example, it may not be sufficiently wet and spread, the line width may be insufficient, and the glossiness and texture of the image may deteriorate.

  As described above, when an image is formed using a photocurable ink composition on a non-absorbent recording medium, it is relatively difficult to form a desired image. For example, in the method described in Patent Document 1 described above, in which the degree of curing is simply 6 to 70% before the ink is completely cured, the fluidity of the droplets is reduced, resulting in higher image definition. Contrary to this, there is a concern that the fluidity is insufficient, the line width is insufficient, and the gloss and texture are not necessarily good.

  One of the objects according to some embodiments of the present invention is that a photocurable ink composition can be used to form an image on a recording medium with little color mixing and good definition and gloss. An ink jet recording apparatus and a recording method using the apparatus are provided.

  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 ink jet recording apparatus according to the present invention is:
A head that is scanned relative to the recording medium, ejects droplets of the photocurable ink composition from the nozzle holes, and adheres the droplets to the recording medium;
The head was scanned relative to the recording medium together with the head, and was disposed at at least one end in the scanning direction of the head at a first distance from the nozzle hole and attached to the recording medium. A first light source for irradiating the droplet with light;
The droplets scanned with the head relative to the recording medium are arranged at a second distance from the end of the first light source opposite to the head, and the droplets attached to the recording medium A second light source that emits light;
The liquid droplets that are scanned relative to the recording medium together with the head, are disposed at a third distance from the end of the second light source opposite to the first light source, and are attached to the recording medium. A third light source that emits light;
With
The first distance has such a magnitude that the light from the first light source is irradiated to the droplet after a time period of 0.001 second or more and 1 second or less after the droplet is attached to the recording medium. And
The second distance has a size such that the light from the second light source is irradiated to the droplet after a time period of 0.001 second to 1 second after being irradiated with the light from the first light source. It is characterized by.

  According to the ink jet recording apparatus of this application example, by providing the first light source and the second light source, two-stage preliminary curing can be performed on the photocurable ink composition before the main curing. Therefore, it is possible to easily control the color mixture, definition and gloss of the image formed on the recording medium. Therefore, for example, using a photocurable ink composition, an image with little color mixing and good definition and gloss can be formed on a recording medium.

[Application Example 2]
In application example 1,
The first distance can be smaller than the second distance.

  According to the ink jet recording apparatus of this application example, after the light from the first light source is irradiated to the droplets of the photocurable ink composition, the light from the second light source is irradiated after a sufficient period of time. Can do. As a result, the surface shape of the droplets attached to the recording medium can be made smoother, and an image with better glossiness can be formed on the recording medium.

[Application Example 3]
In application example 1 or application example 2,
The first light source and the second light source may be light emitting elements having an emission wavelength of 365 nm or more and 410 nm or less.

  According to the ink jet recording apparatus of this application example, since the first light source and the second light source are reduced in size and weight, for example, the degree of freedom in arranging them can be increased.

[Application Example 4]
In any one of Application Examples 1 to 3,
The head is fixed and the recording medium can be scanned.

  The ink jet recording apparatus of this application example is a line type ink jet recording apparatus that can perform recording by scanning a recording medium with respect to a head. According to the inkjet recording apparatus of this application example, similarly to the application example described above, by providing the first light source and the second light source, two-stage preliminary curing is performed on the photocurable ink composition before the main curing. It can be carried out. Therefore, for example, using a photocurable ink composition, an image with little color mixing and good definition and gloss can be formed on a recording medium.

[Application Example 5]
One aspect of the image forming method according to the present invention is:
An image forming method for forming an image with a photocurable ink composition on the recording medium using the ink jet recording apparatus described in any one of Application Examples 1 to 4.
The photocurable ink composition is cured to a curing rate of 1% or more and less than 30% by the light of the first light source, and is cured to a curing rate of 30% or more and less than 85% by the light of the second light source. It is characterized by.

  According to the image forming method of the application example, before the photocurable ink composition is fully cured, the preliminary curing with the first light source and the preliminary curing with the second light source are performed in two stages. Each light is irradiated so that the curing rate of the preliminary curing with the light source is 1% or more and less than 30%, and the curing rate of the preliminary curing with the second light source is 30% or more and less than 85%. Thereby, it is possible to form an image with good definition and gloss while suppressing color mixing of the image formed by the photocurable ink composition.

[Application Example 6]
In application example 5,
The relative scanning speed of the head and the recording medium may be 1 m / min or more and 50 m / min or less.

  According to the image forming method of this application example, it is possible to form an image with high definition and glossiness at high speed while suppressing color mixing of the image formed by the photocurable ink composition.

1 is a perspective view schematically showing an ink jet recording apparatus according to an embodiment. The figure which shows typically the side surface of the inkjet recording head and light source of embodiment. The figure which shows typically the lower surface of the inkjet recording head and light source of embodiment.

  Hereinafter, embodiments of the present invention will be described. In addition, the following embodiment demonstrates an example of this invention. Therefore, this invention is not limited to the following embodiment, The various modifications implemented in the range which does not change a summary are also included. Note that not all of the configurations described in the following embodiments are indispensable constituent requirements of the present invention.

1. Inkjet Recording Apparatus FIG. 1 is a perspective view schematically showing an inkjet recording apparatus 100 that is an embodiment of an inkjet recording apparatus according to the present invention. FIG. 2 is a diagram schematically showing the side surfaces of the head 10 and the light source 20 of the present embodiment. FIG. 3 is a diagram schematically showing the lower surfaces of the head 10 and the light source 20 of the present embodiment.

  The ink jet recording apparatus 100 according to this embodiment includes an ink jet recording head 10, a first light source 21, a second light source 22, and a third light source 23 as the light source 20.

1.1. Inkjet recording head The inkjet recording head 10 according to the present embodiment is scanned relative to the recording medium P, and ejects droplets of the photocurable ink composition from the nozzle holes 12 to apply liquid to the recording medium P. Drops can be deposited. In the present specification, the ink jet recording head 10 may be simply referred to as the head 10.

  The head 10 is not particularly limited as long as it has the above-described function, and any system may be used. As a recording method of the head 10, for example, a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, the ink is continuously ejected in the form of droplets from the nozzle, and the ink droplets are between the deflection electrodes. A method in which a print information signal is applied to the polarizing electrode for recording during flight, or a method in which ink droplets are ejected in accordance with the print information signal without being deflected (electrostatic suction method). Pressure is applied to the ink liquid with a small pump. , A method of forcibly ejecting ink droplets by mechanically vibrating the nozzle with a crystal resonator, etc., a method of simultaneously ejecting and recording ink droplets by simultaneously applying pressure and a printing information signal to the ink liquid with a piezoelectric element ( Piezo method), a method in which 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).

  Among these, the piezo method can be further classified, and can be classified into those having a thin film type ink jet recording head and those having a multilayer type ink jet recording head. The thin film type ink jet recording head includes a so-called unimorph type piezoelectric actuator, and discharges an ink composition from a nozzle by displacement of the piezoelectric actuator. On the other hand, the multilayer ink jet recording head has a mode in which the wall of the pressure chamber communicating with the nozzle is pushed and ejected from the nozzle by d31 mode driving of the multilayer piezoelectric element. The latter ink jet recording head is also referred to as a longitudinal mode ink jet recording head because the piezoelectric element pushes against the wall of the pressure chamber.

  Any of the above-described ink jet recording heads can be used as the head 10 of the present embodiment, but the longitudinal mode method can relatively increase the discharge force of the photocurable ink composition. Thus, it is possible to form a high-quality image at a high speed with less influence of a printing position shift or satellite. On the other hand, in the case of using a thin-film ink jet recording head, since it has a relatively small and lightweight configuration, it can operate at high speed and can form a high-definition and high-quality image at high speed.

  As the recording medium P that can be used in the ink jet recording apparatus 100 of the present embodiment, when a droplet of the photocurable ink composition is attached, the light for curing the droplet reaches the droplet. There is no particular limitation as long as it is possible. The recording medium P preferably has a printing surface that does not absorb or hardly absorbs ink droplets. Examples of the recording medium P having such a printing surface include non-absorbing recording media such as metal, glass, and plastic. The recording medium P may be colorless and transparent, translucent, colored and transparent, chromatic color opaque, achromatic color opaque, and the like. Further, the recording medium P may be any of a gloss type, a mat type, and a dull type. Examples of such a recording medium P include surface-treated paper such as coated paper, art paper, and cast coated paper, and plastic films such as vinyl chloride sheets and PET films. Examples of commercially available recording media include glossy vinyl chloride sheets (for example, trade name SP-SG-1270C: manufactured by Roland DG Corporation), PET films (for example, trade name XEROX FILM <no frame>: manufactured by Fuji Xerox Co., Ltd.), and the like. .

  The scanning of the head 10 relative to the recording medium P means that at least one of the head 10 and the recording medium P moves and the positional relationship between the two changes. For example, in the serial type ink jet recording apparatus 100 as shown in FIG. 1, the head 10 is moved by the operation of the carriage 50, and the recording medium P is moved by the operation of the platen 40 by the drive of the motor 30. By these operations, the relative positional relationship between the recording medium P and the head 10 changes. Thereby, the photocurable ink composition can be attached to different positions on the recording medium P. The speed at which the head 10 is scanned relative to the recording medium P is not particularly limited, but may be, for example, 1 m / min or more and 50 m / min or less.

  Although details will be described later, the light source 20 attached to the head 10 of the present embodiment is provided on at least one end side of the head 10 in the scanning direction MS. Although not shown, even in the case of an ink jet recording apparatus (for example, a line type printer) of a type in which the head does not move and the recording medium P moves, the light source 20 attached to the head 10 is the scanning direction of the head 10. It can be provided on the end side in the scanning direction SS of the recording medium P.

  The nozzle hole 12 is formed on the surface of the head 10 that faces the recording medium P. The head 10 can eject droplets of the photocurable ink composition through the nozzle holes 12. The number and arrangement of the nozzle holes 12 are not particularly limited. As shown in FIG. 3, in the head 10 of this embodiment, the nozzle holes 12 are provided in a row in a direction orthogonal to the moving direction of the carriage 50 (a direction along the scanning direction SS). Eight rows are formed in parallel along the scanning direction MS of the carriage 50.

1.2. Light Source The ink jet recording apparatus 100 according to this embodiment includes a first light source 21, a second light source 22, and a third light source 23. In the present specification, the first light source 21, the second light source 22, and the third light source 23 may be collectively referred to as the light source 20.

1.2.1. First Light Source The first light source 21 is scanned relative to the recording medium P together with the head 10 described above. Since the relative scanning content of the first light source 21 is the same as the scanning content of the head 10 described above, the description thereof is omitted.

  The first light source 21 moves with the above-described head 10 and is disposed at at least one end of the head 10 in the scanning direction. In the serial type ink jet recording apparatus 100 as shown in FIG. 1, it is preferable that one first light source 21 be provided at each end of the head 10 in the scanning direction (arrow MS in the figure). Although not shown, in a line-type ink jet recording apparatus of a type in which the head 10 is fixed and only the recording medium P is scanned, the downstream side in the scanning direction of the recording medium P (the photocurable ink composition is the recording medium). After adhering to P, it is preferably provided at one end of the side on which light from the first light source 21 can be irradiated: the tip side of the arrow SS in the figure. In the line-type ink jet recording apparatus, the first light source 21 may be provided on the upstream side in the scanning direction SS of the recording medium P (on the opposite side to the direction of the arrow SS in the drawing).

  The shape of the first light source 21 is not particularly limited, but the photocurable ink composition ejected from the nozzle holes 12 of the head 10 by one scan of the carriage 50 or one scan of the recording medium P is used. It is preferable that the droplet has a shape that can be irradiated with light. For example, in the example of FIG. 3, the nozzle hole 12 of the head 10 has a shape of the first light source 21 that can draw a locus including a locus drawn when the carriage 50 is scanned. Further, the size of the first light source 21 in the scanning direction and the distance between the first light source 21 and the recording medium P are arbitrarily set in consideration of the intensity of light to be irradiated, the period of irradiation, and the like. Can do.

  Examples of the light generated from the first light source 21 include electromagnetic waves such as 400 nm to 200 nm ultraviolet light, visible light, far ultraviolet light, g-line, h-line, i-line, KrF excimer laser light, ArF excimer laser light, and X-rays. Is mentioned. The light generation means of the first light source 21 is not particularly limited. Specific examples of the first light source 21 include, for example, metal halide lamps, xenon lamps, carbon arc lamps, chemical lamps, low-pressure mercury lamps, high-pressure mercury lamps, H lamps, D lamps, V lamps (Fusion System, etc.) And the like that guide light to the first light source 21 by a light guide, an optical fiber, or the like. Moreover, as a specific aspect of the other first light source 21, for example, a light emitting element such as an ultraviolet light emitting diode (ultraviolet LED) or an ultraviolet light emitting semiconductor laser can be used. When the light generating means of the first light source 21 is such a light emitting element, for example, the emission wavelength can be 365 nm or more and 410 nm or less. Selecting such a wavelength facilitates selection of the photopolymerization initiator in the photocurable ink composition. Moreover, when a light emitting element is selected as the light generating means of the first light source 21, the first light source 21 can be reduced in size and weight, and the degree of freedom in the arrangement of the first light source 21 can be increased. For example, in the example of FIG. 3, the first light source 21 has a configuration in which a plurality of ultraviolet light emitting diodes (ultraviolet LEDs) (symbol D) are arranged along the row of nozzle holes 12.

  The first light source 21 can irradiate the droplets of the photocurable ink composition attached to the recording medium P with light. The first light source 21 may continue to generate light, or may blink or increase / decrease the light. The first light source 21 is a first light source at a time interval of 0.001 second or more and 1 second or less after a droplet of the photocurable ink composition is ejected from the nozzle hole 12 of the head 10 and adheres to the recording medium P. 21 is provided at a position where the light generated from 21 is irradiated. In addition, the first light source 21 is provided such that the light generation site thereof is located at a first distance G1 from the nozzle hole 12 closest to the first light source 21 of the head 10.

  That is, the position where the first light source 21 is installed is changed depending on the scanning speed of the carriage 50 and the recording medium P. For example, if the first distance G1 between the nozzle hole 12 closest to the first light source 21 and the light generation site of the first light source 21 is 10 mm, the scanning speed of the carriage 50 is 10 m / min. The light generated from the first light source 21 is irradiated 0.06 seconds after being ejected from the nozzle hole 12 and attached to the recording medium P. Similarly, for example, if the first distance G1 between the nozzle hole 12 closest to the first light source 21 and the light generation part of the first light source 21 is 140 mm, the scanning speed of the carriage 50 is 20 m / min. Is emitted from the first light source 21 after 0.42 seconds after being ejected from the nozzle hole 12 and attached to the recording medium P. These values are exemplifications of the actual size of each component. The actual size of the ink jet recording apparatus 100 of the present embodiment is 0.001 second or more after being ejected from the nozzle holes 12 of the head 10 and attached to the recording medium P. There is no limitation as long as the light generated from the first light source 21 is irradiated at a time interval of 1 second or less.

  The first distance G1 is 0.001 seconds after the droplets of the photocurable ink composition are ejected from the nozzle holes 12 of the head 10 and adhere to the recording medium P under various conditions as described above. The position is set such that the light emitted from the first light source 21 is irradiated at a time interval of 1 second or less.

  One of the functions of the first light source 21 is to perform a curing reaction of droplets of the photocurable ink composition attached to the recording medium P. If the recording medium P is non-absorbing, the droplets of the photocurable ink composition may spread unnecessarily on the recording medium P or may merge with other droplets if the recording medium P is uncured. Or mix more colors than necessary. After the droplets are attached, the light from the first light source 21 is irradiated within the above-described time range, whereby a part of the photocurable ink composition constituting the droplets is cured, and the recording medium P It is possible to suppress the above-described wet spreading more than necessary, and the mixing of other droplets with an unnecessarily mixed color or the like. In this specification, such an aspect of light irradiation may be referred to as “pinning”. In other words, one of the functions of the first light source 21 is to pin the droplets of the photocurable ink composition.

  The degree of pinning by the first light source 21 can be expressed by the conversion rate (curing rate) of the photocurable ink composition in the droplet, that is, the ratio of the cured composition to the composition of the entire droplet. For example, when expressed as a conversion rate (curing rate), it is preferably 1% or more and less than 30%. The pinning by the first light source 21 is performed in order to prevent the liquid droplets of the photocurable ink composition from spreading significantly wet and remarkably mixing colors, and does not completely suppress these phenomena. If the degree of pinning by the first light source 21 is 30% or more in the conversion rate, the viscosity of the droplet becomes too high, and the necessary wetting spread and the necessary color mixture may not be obtained. For example, the gloss and texture of the formed image may be adversely affected. The degree of pinning by the first light source 21 is more preferably 1% or more and less than 10%, and further preferably 1% or more and less than 5%, in terms of forming large dots quickly.

  The degree of pinning by the first light source 21 is the amount of light from the first light source 21, increase / decrease in the amount of light, blinking, size in the scanning direction, distance from the recording medium P, and in the photocurable ink composition. By adjusting at least one of the amount of the photopolymerization initiator and the kind of the color material, the above range can be set.

1.2.2. Second Light Source The second light source 22 is scanned relative to the recording medium P together with the head 10 described above. Since the relative scanning content of the second light source 22 is the same as the scanning content of the head 10 described above, the description thereof is omitted.

  The second light source 22 moves together with the head 10 described above, and is disposed at the end of the first light source 21 opposite to the head 10 with an interval of the second distance G2. When the first light source 21 is provided at both ends of the head 10, two second light sources 22 are provided on the opposite side, that is, at both ends of the two first light sources 21. Although not shown, the second light source 22 is also arranged at the end of the first light source 21 opposite to the head 10 with an interval of the second distance G2 in the line type ink jet recording apparatus. .

  The shape of the second light source 22 is not particularly limited, but the photocurable ink composition ejected from the nozzle holes 12 of the head 10 by one scan of the carriage 50 or one scan of the recording medium P is used. It is preferable that the droplet has a shape that can be irradiated with light.

  Since the light generated from the second light source 22 is the same as that of the first light source 21 described above, description thereof is omitted. In the example of FIG. 1, the second light source 22 has a configuration in which a plurality of ultraviolet light emitting diodes (ultraviolet LEDs) (symbol D) are arranged along the row of nozzle holes 12. Note that the configurations of the first light source 21 and the second light source 22 may be different from each other in terms of type and wavelength.

  The second light source 22 can irradiate the droplets of the photocurable ink composition attached to the recording medium P with light. The second light source 22 may continue to generate light, or may blink or increase / decrease the light. The second light source 22 is generated from the second light source 22 at a time interval of 0.001 second or more and 1 second or less after the light of the first light source 21 is irradiated to the droplets of the photocurable ink composition. It is provided so as to be a position where light is irradiated. Further, the second light source 22 is provided at a position where the light generation site is spaced from the light generation site of the first light source 22 by a second distance G2.

  That is, the position where the second light source 22 is installed is changed depending on the scanning speed of the carriage 50 and the recording medium P, as described in the first light source 21. For example, if the light generation part of the second light source 22 is 20 mm (second distance G2) from the light generation part of the first light source 22, the first light source is used when the scanning speed of the carriage 50 is 10 m / min. After the 21 light is irradiated, the light generated from the second light source 22 is irradiated 0.12 seconds later. Similarly, for example, if the light generation part of the second light source 22 is 140 mm (second distance G2) from the light generation part of the first light source 22, when the scanning speed of the carriage 50 is 20 m / min, After the light from the first light source 21 is irradiated, the light generated from the second light source 22 is irradiated after 0.42 seconds.

  The second distance G2 is a time period of 0.001 second or more and 1 second or less after the photocurable ink composition droplet is irradiated with the light from the first light source 21 under the various conditions as described above. It is set so that the light emitted from the second light source 21 is irradiated at intervals. These values are exemplifications of the actual size of each component. The actual size of the ink jet recording apparatus 100 according to the present embodiment is such that the second light source 22 converts the light of the first light source 21 into the droplets of the photocurable ink composition. Is not limited as long as the light emitted from the second light source 22 is irradiated at a time interval of 0.001 second or more and 1 second or less after the irradiation.

  One of the functions of the second light source 22 is to perform a curing reaction of the droplets of the photocurable ink composition attached to the recording medium P. If the recording medium P is non-absorbing, the droplets of the photocurable ink composition may spread unnecessarily on the recording medium P or may merge with other droplets if the recording medium P is uncured. Or mix more colors than necessary. In the inkjet recording apparatus 100 of the present embodiment, such a phenomenon is suppressed by the first light source 21 described above, an appropriate conversion rate (viscosity of droplets) is provided, and controlled wetting spread and color mixing are performed. It is performed during a period (0.001 second or more and 1 second or less) until the light from the second light source 22 is irradiated. Then, the light from the second light source 22 further cures a part of the photocurable ink composition constituting the droplet, spreads on the recording medium P, and merges with other droplets. Controls color mixing. That is, in the ink jet recording apparatus 100 of the present embodiment, the shape, wet spread, and color mixing degree of the droplets of the photocurable ink composition are reduced by the two pinnings using the light from the first light source 21 and the light from the second light source. Can be controlled.

  The degree of pinning after the irradiation of the light from the second light source 22 is preferably, for example, 30% or more and less than 85% in the total of the curing rate by the light from the first light source 21. If the degree of pinning by the second light source 22 is 85% or more in terms of the conversion rate, the viscosity of the droplets becomes too high, and the necessary wetting spread and necessary color mixing may not be obtained. In addition, when the degree of pinning by the second light source 22 is 85% or more in terms of conversion, the shape of the droplet is maintained as it is attached, and for example, the gloss and texture of the formed image are adversely affected. There may be. The degree of pinning by the second light source 22 is, for example, more preferably 40% or more and less than 85%, and further preferably 50% or more and less than 85% in terms of ensuring a sufficient line width. .

  The degree of pinning by the second light source 22 is the amount of light from the second light source 22, the increase or decrease in the amount of light, the blinking, the size in the scanning direction, the distance from the recording medium P, and the photocurable ink composition. It can set to the said range by adjusting at least 1 type, such as the quantity of a photoinitiator, and the kind of coloring material.

  Further, as described above, the first distance G1 and the second distance G2 are set so that the above-described time interval can be realized, but the first distance G1 may be smaller than the second distance G2. it can. In this way, when the scanning speed of the carriage 50 or the recording medium P is constant, wetting and spreading of the droplets of the photocurable ink composition adhering to the recording medium P are caused by the first light source 21. While being controlled by light, it is possible to lengthen the period during which wetting spread and color mixing occur in the controlled state. Thereby, it is possible to easily control the dot diameter and surface unevenness of the droplet.

1.2.3. Third Light Source The third light source 23 is scanned relative to the recording medium P together with the head 10 described above. Since the relative scanning content of the third light source 23 is the same as the scanning content of the head 10 described above, the description thereof is omitted.

  The third light source 23 moves together with the head 10 described above, and is disposed at the end of the second light source 22 opposite to the head 10 with an interval of a third distance G3. When the first light source 21 is provided at both ends of the head 10, two third light sources 23 are provided on the opposite side, that is, at both ends of the two second light sources 22. Although not shown, the third light source 23 is also arranged at the end of the second light source 22 on the side opposite to the head 10 with an interval of a third distance G3 in the line type ink jet recording apparatus. .

  The shape of the third light source 23 is not particularly limited, but the photocurable ink composition ejected from the nozzle hole 12 of the head 10 by one scan of the carriage 50 or one scan of the recording medium P is used. It is preferable that the droplet has a shape that can be irradiated with light.

  Since the light generated from the third light source 23 is the same as that of the first light source 21 described above, description thereof is omitted. In the example of FIG. 1, the third light source 23 has a configuration in which a plurality of ultraviolet light emitting diodes (ultraviolet LEDs) (symbol D) are arranged along the row of nozzle holes 12. The first light source 21, the second light source 22, and the third light source 23 may be different from each other in configuration type, wavelength, and the like.

  The third light source 23 can irradiate the droplets of the photocurable ink composition attached to the recording medium P with light. The third light source 23 may continue to generate light, or may blink or increase / decrease the light. The arrangement of the third light source 23 is not particularly limited, and the size of the third distance G3 is not particularly limited.

  One of the functions of the third light source 23 is to perform a curing reaction of the droplets of the photocurable ink composition attached to the recording medium P. When the recording medium P is non-absorbing, the photocurable ink composition droplets are subjected to two-stage pinning by the light of the first light source 21 and the second light source 22, and then, The light curable ink composition can be sufficiently cured by the light from the third light source 23 (main curing). Therefore, since the pinning is performed twice by the irradiation of the light from the first light source 21 and the second light source 22, the size of the third distance G3 is appropriately arranged according to the restriction of the arrangement in the apparatus, for example. Can. For example, when the cumulative curing rate is as low as about 30% to 50% due to the light irradiation of the second light source 22, the shape of the droplet may change after two pinnings. Alternatively, the third light source 23 can be arranged by appropriately setting the third distance G3. In this case, the shape and wet spread of the photocurable ink composition droplets can be controlled by the size of the third distance G3.

  The degree of curing after irradiation of the light from the third source 23 is preferably, for example, 85% or more and 100% or less in the total of the curing rates by the light from the first light source 21 to the third light source 23. If the degree of curing by the third light source 23 (main curing) is 85% or more in terms of conversion, sufficient curing is achieved, but more preferably 90% or more.

  The degree of the main curing by the third light source 23 is the amount of light from the third light source 23, increase / decrease in the amount of light, blinking, size in the scanning direction, distance from the recording medium P, and photocurable ink composition. It can set to the said range by adjusting at least 1 type, such as the quantity of a photoinitiator in it, and the kind of coloring material.

1.3. Other Configurations The ink jet recording apparatus 100 according to the present embodiment can have the following configurations.

  In the ink jet recording apparatus 100 exemplified in the present embodiment, as described above, the head 10 is a serial head for full color printing that ejects ink of three or more colors, and includes a large number of nozzle holes 12 for each color. It has been. In addition to the head 10, a plurality of cartridges 52 as ink containers containing various photocurable ink compositions supplied to the head 10 are mounted on the carriage 50 on which the head 10 is mounted. The ink stored in each cartridge 52 is a photocurable ink composition to be described later. The photocurable ink composition ejected by the head 10 may be one color or two or more colors.

  Further, the ink jet recording apparatus 100 shown in FIG. 1 includes a motor 30 that sends the recording medium P in the scanning direction SS, a platen 40, a carriage 50 on which the head 10 is mounted, and a carriage motor that moves the carriage 50 in the scanning direction MS. 60.

  The carriage 50 is pulled by a pulling belt 62 driven by a carriage motor 60 and moves along a guide rail 64. The head 10 is mounted on the carriage 50, and moves in the scanning direction MS as the carriage 50 moves in the scanning direction MS.

  In the illustrated ink jet recording apparatus 100, 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 10 where the nozzle holes 12 are formed when stopped. ing. 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 10 on which the nozzle holes 12 are formed. it can.

1.4. Photocurable Ink Composition Examples of the photocurable ink composition ejected by the head 100 of the ink jet recording apparatus 100 of the present embodiment include those containing at least a polymerizable compound and a photopolymerization initiator. It is done.

1.4.1. Polymerizable compound The photocurable ink composition of this embodiment contains a polymerizable compound. Examples of such polymerizable compounds include those having at least one of photocationic polymerizability and photoradical polymerizability. The polymerizable compound contained in the photocurable ink composition may have a photocationically polymerizable functional group and a photoradical polymerizable functional group in one molecule. The polymerizable compound includes a monomer as a monomer and an oligomer having a dimer to a quanta or a molecular weight of up to about several thousand. Those contents are adjusted so that it may become the viscosity range which can be used as an inkjet ink.

  Examples of the radical photopolymerizable group include those having a radical having an unsaturated double bond capable of radical radical polymerization, such as acryloyl group, methacryloyl group, acrylamide group, methacrylamide group, allyl group, vinyl ether group, A vinyl thioether group, a vinyl amino group, and a vinyl group are exemplified, and from the viewpoint of particularly high photoradical polymerization reactivity, an acryloyl group, an acrylamide group, a methacryloyl group, and a methacrylamide group are more preferable, and an acryloyl group is more preferable. And acrylamide group.

  Specific examples of the monomer of the radical photopolymerizable compound include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid, and esters thereof, and styrene derivatives such as styrene, vinyltoluene, and dimethylstyrene. N-vinyl compounds such as N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide, N-vinylacetamide, N-substituted maleimide, acrylonitrile, acryloylmorpholine, and the like.

  Specific examples of oligomers of radical photopolymerizable compounds include polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligo acrylate, alkyd acrylate, polyol acrylate, polyester methacrylate, polyurethane methacrylate, epoxy methacrylate, polyether methacrylate, oligo methacrylate. , Alkyd methacrylate, polyol methacrylate and the like.

  Among these, as the polymerizable compound of the present embodiment, acrylic acid esters having an acryloyl group, an N-vinyl compound, and acryloylmorpholine are preferable because of excellent photopolymerizability.

  Specific examples of the polymerizable compound include (meth) acrylates, (meth) acrylamides, N-vinyl compounds, and the like.

  Monofunctional (meth) acrylates include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, stearyl (Meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, 2- Ethylhexyl diglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, cyanoethyl (meth) Acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl (meth) acrylate, alkoxyethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) Acrylate, 2- (2-butoxyethoxy) ethyl (meth) acrylate, 2,2,2-tetrafluoroethyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorodecyl (meth) acrylate, 4-butylphenyl (Meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate Glycidyl (meth) acrylate, glycidyloxybutyl (meth) acrylate, glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, hydroxyalkyl (meth) acrylate, 2- Hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, dimethylaminoethyl (meth) acrylate , Diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, trimethoxysilylpropyl (meth) acrylate Acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, trimethoxysilylpropyl (meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, oligoethylene oxide monomethyl ether ( (Meth) acrylate, polyethylene oxide (meth) acrylate, oligoethylene oxide (meth) acrylate, oligoethylene oxide monoalkyl ether (meth) acrylate, polyethylene oxide monoalkyl ether (meth) acrylate, dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl Ether (meth) acrylate, oligopropylene oxide Alkyl ether (meth) acrylate, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl ( (Meth) acrylate, perfluorooctylethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, EO-modified phenol (meth) acrylate, EO-modified cresol (meth) acrylate, EO-modified nonylphenol (meth) acrylate, Examples thereof include PO-modified nonylphenol (meth) acrylate and EO-modified-2-ethylhexyl (meth) acrylate.

  As polyfunctional (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate (DPGD (M) A), tripropylene glycol di (meth) acrylate (TPGD (M) A), 2,4-dimethyl-1,5-pentanediol di (meth) acrylate, butylethylpropanediol di (meth) Acrylate, ethoxylated cyclohexanemethanol di (meth) acrylate, triethylene glycol di (meth) acrylate (TEGD (M) A), polyethylene glycol di (meth) acrylate, oligoethylene glycol di (meth) acrylate, ethylene glycol (Meth) acrylate, 2-ethyl-2-butyl-butanediol di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, EO-modified bisphenol A di ( (Meth) acrylate, bisphenol F polyethoxydi (meth) acrylate, polypropylene glycol di (meth) acrylate, oligopropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 2-ethyl-2-butyl-propane Diol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, tricyclodecane di (meth) acrylate, etc. They include a (meth) acrylate.

  Furthermore, as polyfunctional (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, alkylene oxide modified tri (meth) acrylate of trimethylolpropane, pentaerythritol tri (meth) acrylate , Dipentaerythritol tri (meth) acrylate, trimethylolpropane tri ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, propionate dipentaerythritol tri (meth) acrylate, tri ( (Meth) acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) a Relate, propoxylated trimethylolpropane tri (meth) acrylate, ethoxylated glycerol tri (meth) acrylate: trifunctional, pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, Propionic acid dipentaerythritol tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate: tetrafunctional, sorbitol penta (meth) acrylate, dipentaerythritol penta (meth) acrylate: pentafunctional, dipentaerythritol hexa ( (Meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide modified hexa (meth) acrylate, cap Lactone-modified dipentaerythritol hexa (meth) acrylate or hexafunctional, and the like.

  (Meth) acrylamides include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, Nn-butyl (meth) acrylamide, Nt -Butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) Examples include acrylamide and (meth) acryloylmorpholine.

The N-vinyl compound has a structure in which a vinyl group is bonded to nitrogen (> N—CH═CH ₂ ). Specific examples of the N-vinyl compound include, for example, N-vinylformamide, N-vinylcarbazole, N-vinylindole, N-vinylpyrrole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, and their Derivatives, and N-vinylcaprolactam is particularly preferable among these compounds.

  Examples of the photocationically polymerizable group include an epoxy ring, an oxetane ring, an oxolane ring, a dioxolane ring, and a vinyl ether group. Regarding the epoxy ring, aromatic and alicyclic systems are preferable from the viewpoint of excellent curing speed, and alicyclic epoxy rings are particularly preferable.

  Specific examples of the polymerizable compound having cationic polymerizability include an epoxy compound, a vinyl ether compound, an oxetane compound and the like as the cationic polymerizable compound.

  The content of the polymerizable compound contained in the photocurable ink composition is suitably 5% by mass or more and 95% by mass or less, and preferably 7% by mass or more and 90% by mass with respect to the entire photocurable ink composition. Hereinafter, it is more preferably in the range of 10% by mass to 80% by mass.

1.4.2. Photopolymerization initiator The photocurable ink composition of this embodiment contains a photopolymerization initiator. As a photoinitiator, the substance which produces the active seed | species which causes superposition | polymerization of a polymeric compound by light can be mentioned.

  Photopolymerization initiators that generate radicals by light (photoradical polymerization initiators) include arylalkyl ketones, oxime ketones, S-phenyl thiobenzoate, titanocene, aromatic ketones, thioxanthones, benzyl and quinone derivatives, ketocoumarins, etc. Conventional initiators known in the art can be used.

  Specific examples of the photo radical polymerization initiator include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, benzophenone, 2-chlorobenzophenone, p, p′-dichlorobenzophenone, p, p′-bisdiethylaminobenzophenone. Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-propyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal, 2,2-dimethoxy-1,2- Diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] Enyl} 2-methylpropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1,2-dimethylamino-2- (4-methylbenzyl) -1- ( 4-morpholin-4-yl-phenyl) butan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2, 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinopropan-1-one, thioxanthone, 2-chlorothioxanthone, 2 -Hydroxy-2-methyl-1-phenyl-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-methylbenzoyl fill formate, azo-bis-isobutyronitrile Lilo nitrile, benzoyl peroxide, di -tert- butyl peroxide, and the like.

  Examples of commercially available photo radical polymerization initiators include IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-ketone), DAROCUR 1173. (2-hydroxy-2-methyl-1-phenyl-propan-1-one), IRGACURE 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane- 1-one), IRGACURE 127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one), IRGACURE 907 (2-Methyl-1- (4-methylthiophenyl) -2-morphol Linopropan-1-one), IRGACURE 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1), IRGACURE 379 (2- (dimethylamino) -2-[(4- Methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), DAROCUR TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), IRGACURE 819 (bis (2, 4,6-trimethylbenzoyl) -phenylphosphine oxide), IRGACURE 784 (bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1-) Yl) -phenyl) titanium), IRGACURE OXE 01 (1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)]), IRGACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (Mixture of (2-hydroxyethoxy) ethyl ester) (manufactured by Ciba Japan KK), DETX-S (2,4-diethylthioxanthone) (Nippon Kayaku Co., Ltd. )), Lucirin TPO, LR8883, LR8970 (above, manufactured by BASF), and Ubekrill P36 (manufactured by UCB) ).

  Photopolymerization initiators that generate cations (acids) by light (photocation polymerization initiators) include onium salts such as arylsulfonium salts and aryliodonium salts, o-nitrobenzyl tosylate, and arylsulfonic acid p-nitrobenzyl esters. And an acid generator such as an initiator that generates a sulfonic acid such as a sulfonium acetophenone derivative, an allene-ion complex derivative such as an iron-allene complex, a diazonium salt derivative, a triazine-based initiator, and other halides. Specific examples of the cationic photopolymerization initiator include arylsulfonium salt derivatives such as Syracure UVI-6990, Syracure UVI-6974 manufactured by Union Carbide, Adekaoptomer SP-150, Adekaoptomer manufactured by Asahi Denka Kogyo Co., Ltd. SP-152, Adeka optomer SP-170, Adeka optomer SP-172 and the like are mentioned. As the allyl iodonium salt derivative, RP-2074 made by Rhodia is mentioned, and as the allene-ion complex derivative, Ciba Geigy is made. Irgacure 261 and the like.

  The content of the polymerization initiator contained in the photocurable ink composition is preferably 1% by mass or more and 20% by mass or less, and preferably 3% by mass or more and 15% by mass with respect to the entire photocurable ink composition. More preferably, it is contained below. By setting it as the said range, there exists an effect of hold | maintaining sclerosis | hardenability, without reducing the mechanical strength of the photocurable ink composition after hardening. As the photopolymerization initiator, those having sensitivity to irradiated light can be appropriately selected and used. Further, the degree of pinning of the droplets of the photocurable ink composition can be adjusted by the type and blending amount of the photopolymerization initiator. For example, when it is desired to reduce the degree of pinning, the degree of pinning can be adjusted by reducing the amount of light from the first light source 21 and the second light source 22, but within this range the amount of photopolymerization initiator is reduced. This can also be done.

  As the polymerizable compound and the photopolymerization initiator, a photoradical polymerization initiator is used for photopolymerization of the photoradical polymerizable compound, and a photocationic polymerization initiator is used for photopolymerization of the photocationic polymerizable compound. When using a radical photopolymerizable compound and a cationic photopolymerizable compound together, a radical photopolymerization initiator and a cationic photopolymerization initiator are used in combination.

1.4.3. Other components 1.4.3.1. Color Material The photocurable ink composition of the present embodiment can contain a color material and a dispersant.

  In this case, examples of the color material include pigments and dyes, and a color material that can be used for normal ink can be used without any particular limitation.

  The ink composition of the present embodiment may further include a color material. The coloring material is selected from pigments and dyes, but it is preferable to use pigments from the viewpoint of light resistance. In this embodiment, the light resistance of the ink composition can be improved by using a pigment as the color material. As the pigment, both inorganic pigments and organic pigments can be used. The ink composition preferably contains 1 to 10% by mass of the color material, and more preferably 1 to 5% by mass.

  As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used.

  Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Polycyclic pigments, dye chelates (for example, basic dye chelates, acid dye chelates, etc.), dye rakes (basic dye rakes, acid dye rakes), nitro pigments, nitroso pigments, aniline black, daytime A photofluorescent pigment is mentioned. The said pigment may be used individually by 1 type, and may use 2 or more types together.

  More specifically, as an inorganic pigment used for black, the following carbon black, for example, No. manufactured by Mitsubishi Chemical Corporation is used. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; Cabot Regal 400R, Regal 330R, Regal 660L, Monal 660R 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color Black FW1, Color Black FW2, Bck, Col Black FW2, Cck W200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, or Special Black 4 and the like.

  The yellow organic pigments include CIPigment Yellow 1, CIPigment Yellow 2, CIPigment Yellow 3, CIPigment Yellow 4, CIPigment Yellow 5, CIPigment Yellow 6, CIPigment Yellow 7, CIPigment Yellow 10, CIPigment Yellow 11 , CIPigment Yellow 12, CIPigment Yellow 13, CIPigment Yellow 14, CIPigment Yellow 16, CIPigment Yellow 17, CIPigment Yellow 24, CIPigment Yellow 34, CIPigment Yellow 35, CIPigment Yellow 37, CIPigment Yellow 53 , CIPigment Yellow 55, CIPigment Yellow 65, CIPigment Yellow 73, CIPigment Yellow 74, CIPigment Yellow 75, CIPigment Yellow 81, CIPigment Yellow 83, CIPigment Yellow 93, CIPigment Yellow 94, CIPigment Yellow 95 , CIPigment Yellow 97, CIPigment Yellow 98, CIPigment Yellow 99, CIPigment Yellow 108, CIPigment Yellow 109, CIPigment Yellow 110, CIPigment Yellow 113, CIPigment Yellow 114, CIPigment Yellow 117, CIPigment Yellow 120, CIPigment Yellow 124, CIPigment Yellow 128, CIPigment Yellow 129, CIPigment Yellow 133, CIPigment Yellow 138, CIPigment Yellow 139, CIPigment Yellow 147, CIPigment Yellow 151, CIPigment Yellow 153, CIPigment Yellow 154, CIPigment Yellow 167, CIPigment Yellow 172, CIPigment Yellow 180, and the like.

  As magenta organic pigments, CIPigment Red 1, CIPigment Red 2, CIPigment Red 3, CIPigment Red 4, CIPigment Red 5, CIPigment Red 6, CIPigment Red 7, CIPigment Red 8, CIPigment Red 9 , CIPigment Red 10, CIPigment Red 11, CIPigment Red 12, CIPigment Red 14, CIPigment Red 15, CIPigment Red 16, CIPigment Red 17, CIPigment Red 18, CIPigment Red 19, CIPigment Red 21 , CIPigment Red 22, CIPigment Red 23, CIPigment Red 30, CIPigment Red 31, CIPigment Red 32, CIPigment Red 37, CIPigment Red 38, CIPigment Red 40, CIPigment Red 41, CIPigment Red 42 , CIPigment Red 48 (Ca), CIPigment Red 48 (Mn), CIPigment Red 57 (Ca), CIPigment Red 57: 1, CIPigment Red 88, CIPigment Red 112, CIPigment Red 114, CIPigment Red 122, CIPigment Red 123, C .I.Pigment Red 144, CIPigment Red 146, CIPigment Red 149, CIPigment Red 150, CIPigment Red 166, CIPigment Red 168, CIPigment Red 170, CIPigment Red 171, CIPigment Red 175, CIPigment Red 176, CIPigment Red 177, CIPigment Red 178, CIPigment Red 179, CIPigment Red 184, CIPigment Red 185, CIPigment Red 187, CIPigment Red 202, CIPigment Red 209, CIPigment Red 219, CIPigment Red 224, CIPigment Red 245, or CIPigment Violet 19, CIPigment Violet 23, CIPigment Violet 32, CIPigment Violet 33, CIPigment V iolet 36, CIPigment Violet 38, CIPigment Violet 43, CIPigment Violet 50, etc. Can be mentioned.

  Examples of cyan organic pigments include CIPigment Blue 1, CIPigment Blue 2, CIPigment Blue 3, CIPigment Blue 15, CIPigment Blue 15: 1, CIPigment Blue 15: 2, CIPigment Blue 15: 3, CIPigment Blue 15:34, CIPigment Blue 15: 4, CIPigment Blue 16, CIPigment Blue 18, CIPigment Blue 22, CIPigment Blue 25, CIPigment Blue 60, CIPigment Blue 65, CIPigment Blue 66, CIVat Blue 4 , CIVat Blue 60 and the like.

  Examples of organic pigments other than magenta, cyan and yellow include CIPigment Green 7, CIPigment Green 10, CIPigment Brawn 3, CIPigment Brawn 5, CIPigment Brawn 25, CIPigment Brawn 26, CIPigment Orange 1 , CIPigment Orange 2, CIPigment Orange 5, CIPigment Orange 7, CIPigment Orange 13, CIPigment Orange 14, CIPigment Orange 15, CIPigment Orange 16, CIPigment Orange 24, CIPigment Orange 34, CIPigment Orange 36 , CIPigment Orange 38, CIPigment Orange 40, CIPigment Orange 43, CIPigment Orange 63, and the like.

  In the present embodiment, in addition to the organic pigments listed above, dyes that are insoluble or hardly soluble in water, such as disperse dyes and oil-soluble dyes, can also be suitably used.

  When the above pigment is used as a coloring material for ink jet recording ink, the average particle diameter is preferably 500 nm or less, more preferably 200 nm or less, and further preferably 50 to 100 nm. When the average particle diameter of the core substance is within such a range, the ink for ink jet recording is effective in reliability such as ejection stability and dispersion stability, and can output a high-quality image.

  When the photocurable ink composition of the present embodiment contains a color material, the addition amount of the color material is preferably in the range of about 0.1% by mass or more and 25% by mass or less, more preferably 0.5% by mass. The range is about 15% by mass or less. Further, the degree of pinning of the droplets of the photocurable ink composition can be adjusted by the type and blending amount of the color material. For example, when it is desired to reduce the degree of pinning, the degree of pinning can be adjusted by reducing the light amounts of the first light source 21 and the second light source 22, but the type of the color material exemplified above can be selected, This can also be done by changing the blending amount of the colorant within the range.

  Further, when a pigment is contained in the photocurable ink composition, a pigment dispersion obtained by dispersing in a medium with a dispersant or a surfactant can be used. Furthermore, when pigments are contained in the photocurable ink composition, these pigments and a dispersant or a surfactant can be contained. As a preferable dispersant, a dispersant conventionally used for preparing a pigment dispersion, for example, a polymer dispersant can be used.

  As the dispersant, any dispersant used in ordinary ink can be used. Commercially available products can be used as the dispersant. Specific examples thereof include Hinoact KF1-M, T-6000, T-7000, T-8000, T-8350P, T-8000EL (manufactured by Takefu Fine Chemical Co., Ltd.). ) Polyester polymer compounds such as solsperse 13940, 20000, 24000, 32000, 32500, 33500, 34000, 35200, 36000 (manufactured by Lubrizol Corporation), disperbyk-161, 162, 163, 164, 166, 180, 190, 191, 192 (Bic Chemie), Floren DOPA-17, 22, 33, G-700 (Kyoeisha Chemical Co., Ltd.), Ajisper PB821, PB711 (Ajinomoto Co., Inc.), LP4010, LP4050, LP4055, OLYMER400,401,402,403,450,451,453 can be mentioned those alone or mixed (EFKA Chemicals Co., Ltd.).

  The content when the dispersing agent is contained in the photocurable ink composition is 5% by mass or more and 200% by mass or less with respect to the content of the coloring material (particularly the pigment) in the photocurable ink composition. The content is preferably 30% by mass or more and 120% by mass or less, and may be appropriately selected depending on the color material to be dispersed.

1.4.3.2. Additives The photo-curable ink composition comprising the photo-radical polymerizable compound of the present embodiment may contain a polymerization accelerator. In the case of radical photopolymerization, the polymerization accelerator is not particularly limited, and examples thereof include Darocur EHA, EDB (manufactured by Ciba Specialty Chemicals), EBECRYL 7100 (manufactured by Daicel-Cytec).

  The photocurable ink composition comprising a photoradical polymerizable compound may contain a thermal radical polymerization inhibitor. Thereby, the storage stability of the photocurable ink composition can be improved. Specific examples of the thermal radical polymerization inhibitor include methyl ether hydroquinone (MEHQ) (manufactured by Kanto Chemical Co., Inc.), tert-butyl-p-benzoquinone, Irgastab UV-10, UV-22 (manufactured by Ciba Specialty Chemicals). Etc.

  Further, the photocurable ink composition may contain a surfactant. The surfactant is preferably dissolved in a photopolymerizable compound, and a silicone-based surfactant or a fluorine-based surfactant can be used. As the silicone surfactant, polyether-modified polydimethylsiloxane or polyester-modified polydimethylsiloxane can be used. Specific examples of the silicone surfactant include BYK-347, BYK-348, BYK-UV3500, 3510, 3530, 3570 (manufactured by Big Chemie Japan Co., Ltd.), UV-3500 (manufactured by Ciba Specialty Chemicals). Can be mentioned. These surfactants can also function as slip agents. A preferable addition amount when a surfactant is blended is 0.5% by mass or more and 4.0% by mass or less in the ink composition.

  Furthermore, an ultraviolet absorber, a leveling agent, etc. can be added to the photocurable ink composition of the present embodiment as necessary.

1.5. Curing of Photocurable Ink Composition The photocurable ink composition of the present embodiment contains at least the polymerizable compound and the polymerization initiator. Therefore, the photocurable ink composition can be cured by irradiating light from the light source 20.

When ultraviolet rays are used as the light of the light source 20, the amount of ultraviolet rays applied to the photocurable ink composition is 10 mJ / cm ² or more, 20,000 mJ / cm ² or less, and preferably 50 mJ / cm ² or more. Irradiation is performed in the range of 15,000 mJ / cm ² or less. If the ultraviolet irradiation amount is within the above range, the curing reaction of the polymerizable compound can be sufficiently performed.

  In the ink jet recording apparatus 100 of the present embodiment, the photocurable ink composition is pinned by the light from the first light source 21 and the second light source 22. The curing rate at the time of pinning can be set such that the amount of light irradiation at this point is 100% when the point at which no further curing reaction of the photocurable ink composition occurs is 100%. If a calibration curve of the curing rate with respect to the light irradiation amount is prepared in advance for the photocurable ink composition to be used, the droplets of the photocurable ink composition have a desired curing rate. The light irradiation amount of the first light source 21 and the second light source 22 can be set. In addition, the conversion rate of a photocurable ink composition can be calculated | required from the change value of the light absorbency in the peak of a specific absorption spectrum, for example using FT-IR (Fourier transform infrared spectrophotometer).

1.6. According to the ink jet recording apparatus 100 of the present embodiment, the first light source 21 and the second light source 22 are provided, so that the photocurable ink composition is preliminarily cured in two stages before the main curing (pinning). )It can be performed. Therefore, it is possible to easily control the color mixture, definition and gloss of the image formed on the recording medium. Therefore, for example, using a photocurable ink composition, an image with little color mixing and good definition and gloss can be formed on a recording medium. Further, according to the ink jet recording apparatus 100 of the present embodiment, the first light source 21 and the second light source 22 are arranged at a specific distance from the head 10, so that the light of each light source is turned on. The above two pinnings can be performed. That is, good pinning can be performed without performing control such as blinking of the light of each light source.

2. Image Forming Method The image forming method of the present embodiment includes discharging the above-described photocurable ink composition using the above-described inkjet recording apparatus 100 and attaching it to a recording medium. In the following, an example of an image forming method in which a dot group is formed by ejecting a photocurable ink composition onto a recording medium P using the inkjet recording apparatus 100 and depositing it on the recording medium P will be described.

  The image forming method of the present embodiment includes a droplet discharge step of discharging a droplet of the photocurable ink composition from the head 10, a first irradiation step of irradiating the droplet with light from the first light source 21, A second irradiation step of irradiating the droplets with light from the second light source 22.

2.1. Droplet Discharge Step This step is a step in which the photocurable ink composition is discharged as droplets from the head 10 of the ink jet recording apparatus 100 and the droplets are deposited on the recording medium P.

  In the image forming method of the present embodiment, the amount of liquid droplets ejected from one nozzle hole 12 of the head 10 is preferably 1 pl or more and 20 pl or less. When the amount of droplets is within the above range, the ejection stability is good, and a higher quality image can be obtained. FIG. 2 shows the droplet I attached to the recording medium P by this process.

2.2. Irradiation process 2.2.1. First Irradiation Step This step is a step of irradiating the droplets attached to the recording medium P with the first light source 21. Hereinafter, this process will be described by taking as an example the case where the head 10 moves in the direction of the arrow A shown in FIG.

  The droplet I attached to the recording medium P in the droplet discharge process moves to a position where one light of the first light source 21 is irradiated as a result of the head 10 moving in the direction of arrow A in the figure. This movement is the same when the recording medium moves in the direction of arrow B in the figure when the ink jet recording apparatus is a line type head. As a result, the droplet I is irradiated with the light from the first light source 21. By this step, a curing reaction of the photocurable ink composition constituting the droplet I occurs, and the first pinning of the droplet I is performed. Although not illustrated, in the present embodiment, since the first light source 21 is provided on both sides of the scanning direction of the head 10, the direction of movement of the head 10 and the recording medium P is opposite to the above example. Is the same process.

  The first irradiation process can be performed very easily using the above-described inkjet recording apparatus 100. Then, after the droplet discharge process, the first irradiation process can be performed at a time interval of 0.001 second or more and 1 second or less.

  The degree of pinning in the first irradiation step of the droplet I is set to 1% or more and less than 30% as the curing rate of the photocurable ink composition constituting the droplet I. In this way, it is possible to prevent the droplet I from being greatly wetted and spread on the recording medium P, and to prevent the color mixture from being noticeably mixed, and to produce controlled wet spread and color mixing. . The degree of pinning of the droplet I in the first irradiation step is more preferably 1% or more and less than 10%, and further preferably 1% or more and less than 5% in terms of curing rate.

2.2.2. Second Irradiation Step This step is a step of irradiating the droplets attached to the recording medium P with the second light source 22. Hereinafter, this process will be described by taking as an example the case where the head 10 moves in the direction of the arrow A shown in FIG.

  The droplet I attached to the recording medium P in the droplet discharge process is irradiated with the light of one second light source 22 as a result of the head 10 continuing to move in the direction of arrow A in the figure after the first irradiation process. Move to a position. This movement is the same when the recording medium moves in the direction of arrow B in the figure when the ink jet recording apparatus is a line-type head. As a result, the light from the second light source 22 is irradiated onto the droplet I. By this step, a curing reaction of the photocurable ink composition constituting the droplet I occurs, and the second pinning of the droplet I is performed. Although not shown, in the present embodiment, since the second light source 22 is provided on both sides of the scanning direction of the head 10, the direction of movement of the head 10 and the recording medium P is opposite to the above example. Is the same process.

  The second irradiation process can be performed very easily by using the ink jet recording apparatus 100 described above. And after a 1st irradiation process, a 1st irradiation process can be performed in the time interval within 0.001 second or more and 1 second or less.

  The degree of pinning in the second irradiation step of the droplet I is 30% or more and less than 85% as the curing rate of the photocurable ink composition constituting the droplet I, including the curing rate in the first irradiation step. To be. In this way, for example, when the droplet I on the recording medium P has a desired shape, or when there are a plurality of droplets I, their color mixture can be set to a desired level. Further, the degree of pinning by the second irradiation step is more preferably 40% or more and less than 85%, and further preferably 50% or more and less than 85% in terms of conversion.

2.2.3. Third Irradiation Step The image forming method of the present embodiment may include a third irradiation step. The third irradiation step is a step of irradiating the droplets attached to the recording medium P with the third light source 23.

  The droplet I attached to the recording medium P in the droplet discharge process is one third light source 23 as a result of the head 10 continuing to move in the direction of arrow A in the figure after the first irradiation process and the second irradiation process. It moves to the position where the light is irradiated. This movement is the same when the recording medium moves in the direction of arrow B in the figure when the ink jet recording apparatus is a line type head. As a result, the light from the third light source 23 is irradiated onto the droplet I. By this step, a curing reaction of the photocurable ink composition constituting the droplet I occurs, and the droplet I is fully cured. Although not shown, in the present embodiment, since the third light source 23 is provided on both sides of the scanning direction of the head 10, the direction of movement of the head 10 and the recording medium P is opposite to the above example. Is the same process.

  The third irradiation step can be performed very easily if the above-described ink jet recording apparatus 100 is used. The image forming method of the present embodiment uses the above-described ink jet recording apparatus 100. When the third irradiation step is performed, the droplet I is attached to the recording medium P, and the two pinning and main curing are performed. Can be realized every time the relative scanning of the head 10 and the recording medium P is performed once. Further, by setting the relative scanning speed of the head 10 and the recording medium P to 1 m / min or more and 50 m / min or less, the color mixture of the image formed by the photocurable ink composition is suppressed and the definition is reduced. In addition, an image with good glossiness can be formed at high speed.

3. Experimental Examples Hereinafter, the present invention will be specifically described with reference to some experimental examples, but these do not limit the scope of the present invention.

3.1. Photocurable Ink Composition A set of photocurable ink compositions common to each experimental example was prepared.

  As the polymerizable compound, 29.5% by mass of phenoxy acrylate (V # 192: manufactured by Osaka Organic Industry Co., Ltd.), 19.7% by mass of dicyclopentenyloxyethyl acrylate (FA512AS: manufactured by Hitachi Chemical Co., Ltd.), di 15.8% by mass of cyclopentenyl acrylate (FA511AS: manufactured by Hitachi Chemical Co., Ltd.), 9.8% by mass of vinylcaprolactam, 9.8% of dimethylol tricyclodecane diacrylate (EBECRYL IRR214K: manufactured by Daicel Cytec Co., Ltd.) 5% by mass, 5% by mass of IRGACURE 819 (manufactured by Ciba Specialty Chemicals), 4% by mass of DAROCURE TPO (manufactured by Ciba Specialty Chemicals), and 1 of DETX (manufactured by Nippon Kayaku Co., Ltd.) as a photopolymerization initiator Mass%, polymerization accelerator Then, 3% by mass of EBECRYL 7100 (manufactured by Daicel Cytec Co., Ltd.), as a slip agent, 0.2% by mass of BYK-UV3500 (manufactured by Big Chemie Japan Co., Ltd.), and solsperse 36000 (manufactured by Lubrizol) as a pigment dispersant ) 0.1% by mass and the pigment 2% by mass, mixed and dissolved, and further mixed and stirred with a magnetic stirrer at room temperature and normal pressure for 30 minutes.

  As a set of the photocurable ink composition, as the above-mentioned pigments, cyan pigments: those using IRGALITE BLUE GLVO (manufactured by Ciba Specialty Chemicals), magenta pigments: those using Pigment Red 122, yellow pigments: pigments A set using yellow 180 and a set using carbon black were used.

  After the photocurable ink composition was obtained, methyl ether hydroquinone (manufactured by Kanto Chemical Co., Inc.) and tert-butyl-p-benzoquinone (manufactured by Ciba Specialty Chemicals) were both used as polymerization inhibitors. An ink set common to each experimental example was prepared by adding 2000 ppm.

3.2. Inkjet recording apparatus The evaluation sample of each experimental example was created using a modified inkjet printer PX-G920 (manufactured by Seiko Epson Corporation) as an inkjet recording apparatus. The above-described photocurable ink composition set was introduced into each color ink cartridge of the printer. As a result of the modification, the first light source, the second light source, and the third light source configured by LEDs having a wavelength of 395 nm are provided on both sides in the scanning direction of the head as described in the above embodiment. Yes.

3.3. Preparation of sample for evaluation The sample of each experimental example was prepared by using a vinyl chloride sheet cut to A4 size as a recording medium, and setting the light amount of each light source so that the curing rate shown in Table 1 was obtained. did.

  In any sample, the printer is set up in the print mode of the media “PVC General 1” and the print quality “Pretty”, and the line width of one dot of each color and the density of the solid part can be evaluated, and color bleeding The test pattern was able to evaluate (mixed color) and gloss. Moreover, the light quantity of the 1st irradiation thru | or 3rd irradiation of each experiment example was adjusted as shown in Table 1 with the light quantity of LED. Although not shown, the curing rate of the photocurable ink composition is determined by preparing a calibration curve showing the relationship between the curing rate of the cyan photocurable ink composition and the amount of light, and the value is shown in Table 1. did. The scanning speed of the head was 30 m / min. Note that only the sample of Experimental Example 1 is provided with the second light source so that the first distance G1 described in the above embodiment is smaller than the second distance G2, and in the other experimental examples, the first distance G1 is used. The sample was printed with the same second distance G2.

3.4. Evaluation Method The color bleed, line width, and gloss were evaluated for the obtained samples of each experimental example.

  The color bleed was evaluated by visually observing the test pattern with a loupe or the like. “A” indicates no color bleed, “B” indicates that the test pattern color boundary is unclear, and “C” indicates that color mixing occurs at the test pattern color boundary. It described in Table 1.

  The line width was evaluated by visually observing the test pattern with a loupe or the like. “A” indicates that a sufficient line width is obtained and the solid part is filled with dots, and “B” indicates that the solid part is filled with dots although the line width is narrower than A, but the line width is narrow. Those in which the solid part is not buried are listed in Table 1 as “C”.

  The gloss was evaluated by visually observing the test pattern. Table 1 shows “A” for high gloss, “B” for gloss, and “C” for lack of gloss.

3.5. Evaluation results Table 1 shows that in each experimental example, the color bleed, the line width, and the gloss can be significantly changed by changing the curing rate in the first irradiation and the second irradiation. did. That is, it has been found that if the ink jet recording apparatus used in the experimental example is used, the way in which the droplets of the photocurable ink composition attached to the recording medium spread and the surface shape can be changed in a wide range.

  Further, it was found that the samples of Experimental Example 1 to Experimental Example 7 were all good in color bleed, line width, and gloss. That is, the conversion rate of the photocurable ink composition at the time of the first irradiation is 1% to 30%, and the conversion rate of the photocurable ink composition at the time of the second irradiation is 35% to 80%. It was found that the color bleed, line width, and gloss were all good in the sample with%.

  The embodiments and modified embodiments described above can be arbitrarily combined with a plurality of forms. Thereby, combined embodiment can have an effect which each embodiment has, or a synergistic effect.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. 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 10 ... Inkjet recording head (head), 12 ... Nozzle hole, 20 ... Light source, 21 ... First light source, 22 ... Second light source, 23 ... Third light source, 30 ... Motor, 40 ... Platen, 50 ... Carriage, 52 ... Cartridge, 60 ... carriage motor, 62 ... traction belt, 64 ... guide rail, 80 ... capping device, 100 ... inkjet recording device, P ... recording medium, I ... droplet, MS, SS ... scanning direction

Claims (6)

A head that is scanned relative to the recording medium, ejects droplets of the photocurable ink composition from the nozzle holes, and adheres the droplets to the recording medium;
The head was scanned relative to the recording medium together with the head, and was disposed at at least one end in the scanning direction of the head at a first distance from the nozzle hole and attached to the recording medium. A first light source for irradiating the droplet with light;
The droplets scanned with the head relative to the recording medium are arranged at a second distance from the end of the first light source opposite to the head, and the droplets attached to the recording medium A second light source that emits light;
The liquid droplets that are scanned relative to the recording medium together with the head, are disposed at a third distance from the end of the second light source opposite to the first light source, and are attached to the recording medium. A third light source that emits light;
With
The first distance has such a magnitude that the light from the first light source is irradiated to the droplet after a time period of 0.001 second or more and 1 second or less after the droplet is attached to the recording medium. And
The second distance has a size such that the light from the second light source is irradiated to the droplet after a time period of 0.001 second to 1 second after being irradiated with the light from the first light source. An ink jet recording apparatus. In claim 1,
The ink jet recording apparatus, wherein the first distance is smaller than the second distance. In claim 1 or claim 2,
The inkjet recording apparatus, wherein the first light source and the second light source are light emitting elements having an emission wavelength of 365 nm or more and 410 nm or less. In any one of Claims 1 to 3,
An ink jet recording apparatus in which the head is fixed and the recording medium is scanned. An image forming method for forming an image with a photocurable ink composition on the recording medium using the ink jet recording apparatus according to any one of claims 1 to 4,
The photocurable ink composition is cured to a curing rate of 1% or more and less than 30% by the light of the first light source, and is cured to a curing rate of 30% or more and less than 85% by the light of the second light source. An image forming method. In claim 5,
An image forming method, wherein a relative scanning speed of the head and the recording medium is 1 m / min or more and 50 m / min or less.

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