JP2007268758A - Inkjet head drive device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet head drive device which maintains highly accurate recording of an image for a long time by preventing defective ejection of ink even when images are continuously formed by means of a full-line type ink jet head, and also to provide a method therefor. <P>SOLUTION: There are disclosed the full-line type inkjet head drive device having liquid droplet jet nozzles arranged in a whole width direction of a recording medium and the method for driving the inkjet head. A part of an image in which the prescribed number of pixels that become an image or a non-image is computed based on recording image data corresponding to a conveyance direction of the recording medium. The position of the inkjet head is changed in a front or back side of the computed prescribed number of continuous pixels, thereby changing the position relative to the recording medium. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, an active energy curable ink is ejected toward a recording medium by an ink jet head in which droplet ejection nozzles are arranged in the entire width direction of the recording medium, and the active energy is irradiated to the ink on the recording medium. The present invention relates to an inkjet head driving apparatus and method in active energy curable inkjet recording in which ink attached to a recording medium is cured and fixed.

An inkjet recording apparatus that discharges a functional liquid material to a recording medium is low in cost and relatively friendly to the environment. Recently, the number of types of recording media that can be recorded is increased, and high-speed and high-definition drawing can be performed. Has characteristics.
In recent years, the functional liquid is also used as an active energy curable ink that is cured by irradiation with active energy such as electron beams and ultraviolet rays, and the ink droplets are ejected onto a recording medium by an inkjet head. Various active energy curable ink jet recording apparatuses that perform image recording on a recording medium by curing the ink ejected thereon by irradiation of active energy have been proposed.

  This active energy curable ink jet recording apparatus records on various recording media at a high speed by utilizing the characteristics of the active energy curable ink itself as compared with a general ink jet recording apparatus that does not use an active energy curable ink. It is possible to obtain various advantages such as being able to record images with high definition and being resistant to bleeding, and being environmentally friendly.

  In particular, an apparatus using a UV curable ink that is cured by irradiation with ultraviolet rays as active energy has been developed from the viewpoint of easy handling of a light source, compactness, and the like (for example, see Patent Document 1).

By the way, in a droplet discharge nozzle equipped in such an ink jet head, when a pause operation that does not discharge ink droplets continues for a long time, or when ink droplet discharge is continuously performed for a certain amount or more, Ink ejection failure such as ink droplets bending away from the central axis of the nozzle or flying, or the particle size of the ejected ink droplets becoming non-uniform occurs. Invite. This phenomenon is particularly noticeable when an active energy curable ink is applied.
In other words, ejection failure when a pause operation that does not eject ink droplets continues for a long time is caused by nozzle clogging due to evaporation of solvent in the ink liquid stored around the nozzle opening end, aggregation of components, or separation. In addition, ejection failure when ink droplets are ejected continuously for more than a certain amount is caused by the inclusion of bubbles in the ink liquid stored around the opening end of the nozzle and the meniscus collapse at the nozzle It is.

Therefore, in an ink jet recording apparatus equipped with an ink jet head on a carriage that can reciprocate in the width direction of the recording medium, in order to prevent the above-described ink ejection failure, the outside of the image drawing width on the recording medium A technique for providing a head cleaning process called spitting or wiping in a state where an inkjet head is retracted at a position where the inkjet head is retracted and the inkjet head is retracted in this retracted area has been proposed.
The spitting process is a blanking process that discharges several drops of ink continuously and discards the abnormal ink stored around the nozzle opening end. The ink stored in the periphery is refreshed, and when the next ink droplet is ejected, normal ejection in which the ink droplet accurately flies on the central axis of the nozzle becomes possible.
The wiping process is a process of wiping the open end of the nozzle, and removes the ink aggregating component and foreign matter adhering to the open end of the nozzle to return the open end of the nozzle to a normal state.

JP 2004-90487 A JP 2004-174849 A

By the way, the ink jet head is not of the type mounted on the carriage that reciprocates as described above, and the droplet discharge nozzles are aligned and arranged along the width of the recording medium along the entire width of the recording medium. There is a full-line type that records images in units of drawing lines in the width direction.
Since this full-line type ink jet head is suitable for speeding up image recording, it is widely used in a plate making apparatus for performing a printing plate for printing.

  However, in this full-line type ink jet head, since each droplet discharge nozzle is always located inside the image drawing width, the above-described head cleaning by spitting or wiping cannot be performed.

  For this reason, when continuously recording the same partially biased image pattern, the nozzle that continues to discharge continuously and the nozzle that does not discharge ink droplets at all for a long period of time coexist. There is a problem that ink drawing failure occurs, and it is difficult to continuously form the same image pattern.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and an active energy curable ink is ejected toward a recording medium by an ink jet head in which droplet ejection nozzles are arranged in the entire width direction of the recording medium. When irradiating the ink on the recording medium with active energy to cure and fix the ink attached to the recording medium, ejection failure is not induced by the suspension of the operation of ejecting ink droplets or the continuous ejection operation, To provide an active energy curable ink jet recording method and apparatus capable of preventing high-precision image recording over a long period of time even when the same image pattern is continuously formed by preventing the occurrence of drawing failure due to ejection failure. It is.

The above-mentioned subject concerning the present invention is attained by the following composition.
(1) A full-line type ink jet head drive device comprising droplet discharge nozzles arranged in the entire width direction of a recording medium,
Head driving means for controlling droplet ejection of an ink jet head based on recording image data, and pixels that become an image or non-image pixels from the recording image data corresponding to the transport direction of the recording medium An image data analyzing means for calculating an image portion to be a number, and the inkjet head in a width direction of the recording medium, which is an orthogonal direction of the recording medium conveyance, around a predetermined continuous number of pixels calculated by the image data analysis means A head unit position adjusting mechanism for moving the inkjet head drive device.

  With such a configuration, a pixel or a non-image that becomes an image corresponding to the conveyance direction of the recording medium before occurrence of a drawing defect due to defective ink ejection due to continuous ejection or continuous pause of some nozzles The predetermined continuous number of pixels is calculated by the image data analysis means, and the inkjet head is moved around the predetermined continuous number. As a result, the change of the discharge nozzle is urged without moving the image position. By interrupting the continuous ejection and the continuous pause, the ink ejection failure due to the continuous operation of the nozzles is suppressed, and high-precision image recording can be maintained for a long time. As a result, nozzle clogging can be suppressed, high-speed and high-quality image formation can be performed, and the head life can be extended. Further, since the head is moved only in the direction perpendicular to the conveyance direction of the recording medium, it is simple and compact without using a complicated and large-scale moving mechanism, and it is not necessary to occupy a large space.

(2) The head unit position adjusting mechanism moves the ink jet head from the recording medium position in the recording medium width direction to set a head moving position for spitting at least a part of the head nozzle. The active energy curable ink jet drive device described in 1.
With such a configuration, the predetermined number of pixels is calculated from the recording image data corresponding to the recording medium conveyance direction, and as described above, the inkjet head is moved to the outside of the recording, and the head nozzle It is possible to set a head moving position for spitting at least a part of the head.

(3) The inkjet head driving device according to claim 3, wherein the predetermined number of continuous pixels is 10,000.
As described above, by limiting the number of pixels within 10,000, which is smaller than the number of continuous pixels in which defective ink discharge occurs due to continuous discharge, it is possible to prevent defective ink discharge due to continuous discharge.
(4) A full-line type inkjet head driving method comprising droplet discharge nozzles arranged in the entire width direction of a recording medium,
An image portion in which a pixel that is an image or a pixel that is not an image has a predetermined continuous number is calculated from the recording image data corresponding to the conveyance direction of the recording medium, and the head unit is around the predetermined continuous number of the calculated pixels. An ink jet driving method of moving the ink jet head in a recording medium width direction which is a direction orthogonal to the recording medium conveyance by a position adjusting mechanism.
With such a configuration, a pixel or a non-image that becomes an image corresponding to the conveyance direction of the recording medium before occurrence of a drawing defect due to defective ink ejection due to continuous ejection or continuous pause of some nozzles By calculating the predetermined continuous number of pixels, and moving the ink jet head around the predetermined continuous number, it is possible to prompt the change of the discharge nozzle without moving the image position on the recording medium. Interrupt continuous pauses. Therefore, ink ejection failure due to the continuous operation state of the nozzles is suppressed, and highly accurate image recording can be maintained over a long period of time.

(5) The inkjet head driving method according to (4), wherein the predetermined continuous number of the pixels is a number corresponding to the pre-measured bubble generation before the ink in the nozzle.
(6) The inkjet head driving method according to (4), wherein the predetermined number of continuous pixels is a number corresponding to the pre-measured occurrence of sticking of the ink in the nozzle.
(7) The inkjet head driving method according to (4), wherein the predetermined number of continuous pixels corresponds to the vicinity of 5 minutes in the non-ejection time of the nozzle.

As shown in the above (3), (5), (6), and (7), the head adjustment mechanism is a use situation that is the change timing of the nozzle at the normal position set based on the image position on the recording medium. A predetermined continuous number of pixels that are images or non-image pixels corresponding to the conveyance direction of the recording medium before the occurrence of a drawing failure due to ink ejection failure due to continuous ejection or continuous pause of nozzles. By doing so, it is possible to comprehensively suppress the requirement for nozzle clogging, and it is possible to apply spitting at least a part of the head nozzle by moving the head or suctioning the head nozzle.
Here, the predetermined continuous number of pixels that are images or non-image pixels that correspond to the conveyance direction of the recording medium is a value that causes the mixture of bubbles and the meniscus collapse of the nozzle to begin to become noticeable. The predetermined value of the ejection time is a value at which ink evaporation and aggregation starts to become noticeable in the nozzle, and is a characteristic of the head unit, and is determined by measurement in advance.

  In the inkjet head driving apparatus and method according to the present invention, an image portion in which a pixel that is an image or a pixel that is a non-image is a predetermined continuous number is calculated from the image data for recording corresponding to the conveyance direction of the recording medium, By moving the inkjet head around the calculated number of consecutive pixels, the position of the image is changed before the ink droplet ejection operation pauses or the small volume ejection operation continues beyond a predetermined level. It is possible to reduce the possibility of occurrence and to suppress ink ejection defects due to the continuation of the same operating state of the nozzles. Accordingly, it is possible to provide an active energy curable ink jet recording apparatus that can form a high-speed and high-quality image without nozzle clogging.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an active energy curable ink jet recording method and apparatus according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an embodiment of an active energy curable ink jet recording apparatus for carrying out an active energy curable ink jet recording method according to the present invention, and FIG. 2 is a schematic diagram of the active energy curable ink jet recording apparatus shown in FIG. FIG. 3 is a block diagram of a head driver as a control unit for controlling the ink jet head in the active energy curable ink jet recording apparatus shown in FIG. 1.

The active energy curable ink jet recording apparatus 10 of this embodiment uses, as the active energy curable ink, a UV curable ink that is cured by irradiation with ultraviolet rays.
In FIG. 1, in the casing 12 of the active energy curable ink jet recording apparatus 10, a recording medium storage unit 20 that stores a plurality of sheet-shaped recording media S of the same size, and a storage unit 20. A transport unit 30 that picks up the recording medium S, a scanning transport unit 40 that transports the recording medium S carried by the transport unit 30 while holding it in the recording position range, and a target that is held and transferred by the scanning transport unit 40. An image recording unit 50 that performs inkjet image recording scanning and active energy irradiation fixing on the recording medium S, and a tray 90 to which the recording medium S that has been recorded by the image recording unit 50 is sent out are provided.
An ink supply unit 70 is connected to the image recording unit 50 for supplying ink.

  In the recording medium storage unit 20, a storage cassette 22 that stores recording media S in a stacked state is detachably disposed at the bottom of the housing 12, and recording media S of different sizes can be supplied by replacement. The recording medium storage unit 20 may be configured to mount a plurality of cassettes.

  The transport unit 30 is provided with a feed roller 32 that comes into contact with the leading end of the recording medium S in the storage cassette 22 set in the housing 12 in the insertion direction. Further, the recording medium S fed out by the feed roller 32 is supplied to the transport unit 30. Conveying roller pairs 34 and 36 for conveying to the scanning conveying unit 40 are provided.

  The scanning conveyance unit 40 includes a conveyance belt 42 that is stretched and driven by three belt rollers 44a, 44b, and 44c. The conveyance belt 42 is driven from the upstream belt roller 44b toward the downstream belt roller 44c, and the recording medium S is placed and conveyed on the conveyance belt 42 between the upstream belt roller 44b and the downstream belt roller 44c. A substantially intermediate position between the upstream belt roller 44b and the downstream belt roller 44c is set as an image recording position 42P.

  In the image recording unit 50, an ink-jet head (ink-jet head unit) 52 (detailed configuration and operation will be described later) is provided with the tip of the ink discharge unit facing the conveyance belt 42 at an image recording position 42P. The ink jet head 52 is a full line type head having an array of the lengths in the width direction of the recording medium S as shown in FIG. 2 to be described later, and adopts a piezo type head (described in an example described later). is doing. A head driver 54 is connected to the inkjet head 52 to control the ejection amount of each color of ink. An ink supply unit 70 is connected to the inkjet head 52 for supplying ink via an ink supply path 78. The ink supply unit 70 can be configured to be detachably equipped with an ink cartridge.

Further, an active energy irradiation unit 56 is disposed immediately after the image recording position 42P and downstream of the ink jet head 52, and gives strong energy sufficient to cure immediately after ink is ejected onto the recording medium S.
A separation claw 92 is disposed downstream of the position where the recording medium S is separated from the conveyance belt 42 (the position of the downstream belt roller 44c in this embodiment), and the leading end of the separation claw 92 is near the downstream belt roller 44c. Is peeled off from the conveyor belt 42. The tray 90 accommodates the recording medium S that has been peeled off from the transport belt 42.

  Since the active energy irradiation unit 56 uses strong light for curing the ink as described above, the exhaust cooling unit 80 is disposed in the upper part of the housing 12 in order to suppress the temperature rise in the housing 12. .

Next, the image recording unit of this embodiment will be described.
FIG. 2 is an enlarged perspective view of the image recording unit 50 and the conveyance operation unit 40 of the present embodiment.
The recording medium S supplied from the recording medium storage unit 20 is conveyed by the scanning conveyance unit 40 to the position of the upstream belt roller 44b.
The recording medium S held on the transport belt 42 with a uniform force is used for drawing by the image recording unit 50 when the leading end reaches the image recording position 42P. The ink jet head 52 of the image recording unit 50 has ink ejection openings in the width direction of the transport belt 42, and performs image recording scanning in accordance with the scanning timing of the transport belt 42. At this time, the ink jet head 52 is guided with ink from the ink supply unit 70, and image data is input to the head driver 54 to control the amount of ink discharged from the ink jet head 52.

A head unit position adjusting mechanism 120 is disposed along the longitudinal direction of the head unit 52 (the width direction of the recording medium S). The head unit position adjusting mechanism 120 is provided with a head unit drive control device 122 connected to the head unit 52. In the head unit drive control device 122, a pinion gear (not shown) is coupled to a built-in drive source such as a motor (not shown), and the pinion gear is engaged with the rack 124. With this configuration, the head unit 52 is held movably in the width direction of the recording medium S. The head unit drive control device 122 rotates the pinion gear at a predetermined rotation angle based on the head position signal given from the head driver 54, and moves the head unit 52 to a predetermined position in the length direction of the rack 124. Is moved to slide.
The head unit drive control device 122 may use rails or the like instead of the rack 124, and the motor may be a step motor. Alternatively, a ball screw device may be applied.

  In order to quickly cure the ink that has been ejected onto the recording medium S and in an image-formed state, the active energy irradiation unit 56 is disposed immediately downstream of the inkjet head 52 as described above. The arrangement is such that only the ink discharged to the recording medium S is irradiated, and the ink discharge port of the inkjet head 52 is not irradiated, thereby preventing ink curing at the discharge port. In particular, it is effective to carry out a light reflection preventing treatment (for example, a matte black treatment) on the conveyor belt 42, but such a light reflection preventing treatment may be applied to other parts other than the conveyor belt 42. It is effective.

Next, the configuration of the head driver 54 of the present embodiment and the active energy curable ink jet recording method controlled by the head driver 54 will be described.
FIG. 3 is a block diagram showing the ink jet head driving apparatus of the present embodiment.
As shown in FIG. 3, the head driver 54 that is an ink jet driving device includes a memory 81 that stores recording image data for ink ejection by the ink jet head 52, and pixels or non-images that become images from the recording image data. A pixel data analyzing unit 82 for calculating an image portion in which pixels serving as an image have a predetermined continuous number; a predetermined value setting unit 83 for setting a predetermined continuous number N of pixels as a reference for changing a recording image position by the inkjet head 52; The continuous number n of pixels to be an image or non-image corresponding to the transport direction of the recording medium calculated by the pixel data analysis unit 82 and the predetermined continuous number N set by the predetermined value setting unit 83 If the numerical value calculated by the pixel data analysis means 82 exceeds a predetermined value N, the inkjet head The change position determining means 84 for determining the change position of 52, and the image data for recording converted into the discharge nozzle for the changed position of the ink jet head 52 based on the change position determined by the change position determining means 84 And a head drive control unit 85 for sending to the head 52. The changed position data determined by the changed position determining means 84 is input to the head unit drive control device 122 of the head unit position adjusting mechanism 120, and the head unit moves at an appropriate timing.

  The recording image data stored in the memory 81 can be input from an input unit 86 such as a computer connected to the active energy curable ink jet recording apparatus 10.

  By providing the head driver 54 described above, the active energy curable ink jet recording apparatus 10 performs the ink jet head driving method of the present embodiment shown below. In other words, this is an inkjet head driving method in which the position of the inkjet head is changed based on a predetermined continuous number of pixels that are images or non-image pixels that correspond to the conveyance direction of the recording medium.

Next, FIG. 4 is an external perspective view showing another form of scanning conveyance of the recording medium according to the present invention.
In the embodiment of FIGS. 1 and 2, the sheet-like recording medium S is scanned and conveyed by the conveying belt. However, in the embodiment of FIG. 4, the web-like recording medium S1 wound around the upstream roll 102 is used. Supply. Similarly, the recording medium S is wound around the roll 104 on the downstream side. For this reason, the stationary platen 106 and the conveying roller pairs 108 and 110 are provided on the upstream side and the downstream side of the stationary platen 106. In this way, image recording using a roll-shaped recording medium is also possible.

Next, an example of the operation of the head unit position adjustment mechanism 120 will be described in detail with respect to this embodiment.
5A is a plan view of the head unit position adjusting mechanism 120 in the image recording unit 50 at the first position, and FIG. 5B is a plan view of the head unit position adjusting mechanism 120 in the image recording unit 50 at the second position. FIG. These are based on the transport mode shown in FIG. 4 and are described with nine nozzles, with the number of nozzles being extremely small, for ease of explanation. Ten nozzles are applied.

  When the recording start switch is turned on, one recording medium S is taken out from the storage cassette 22, and the recording medium S is placed on the conveying belt 42 via the feed roller 32 and the conveying roller pairs 34 and 36. Then, it is conveyed on the conveying belt 42 in the X direction. Then, at the image recording position 42 </ b> P, ink is ejected onto the recording medium S from the head unit 52 via the head driver 54 in the form of dots, so that the image M starts to be drawn on the surface of the recording medium S.

  At this time, as shown in FIG. 5A, the head unit drive control device 122 is in the first position A1, and the head unit 52 is in the first position B1. Based on the image data given from the head driver 54, the head drive control unit 85 has four nozzles among the plurality of nine nozzles 52a, 52b, 52c, 52d, 52e, 52f, 52g, 52h, and 52i. 52a, 52c, 52f, and 52h are selected and set. Thus, ink is ejected from the four nozzles 52a, 52c, 52f, and 52h.

Next, as shown in FIG. 5B, after FIG. 5A, it is determined that the numerical value corresponding to the conveyance direction of the recording medium calculated by the pixel data analyzing unit 82 exceeds a predetermined value N. When the image recording position is reached, the head unit drive control device 122 is slid to the second position A2 in the length direction of the rack 124, and the head unit 52 moves to the second position B2. The head drive control unit 85 then controls the four nozzles 52b, 52d, 52g, out of the nine nozzles 52a, 52b, 52c, 52d, 52e, 52f, 52g, 52h, and 52i. 52i is selected and set. Thereby, the ejection of ink from the nozzles 52a, 52c, 52f, and 52h is stopped, and ink is ejected from the four new nozzles 52b, 52d, 52g, and 52i. Thus, the nozzles are used while being shifted in the width direction of the recording medium S.
Here, the movement position of the head unit 52 is determined so as not to move too far from the first position A1 of the head unit drive control device 122 so that the head unit 52 does not move too far to the edge of the recording medium S. Yes. Thus, this operation is repeatedly executed based on the number of continuous pixels. The number of nozzles is an example, and actually, a plurality of nozzles are provided for each color.

  Here, in the inkjet head driving method, the predetermined continuous number N is set to 10,000 pixels in the image data corresponding to the conveyance direction of the recording medium. These figures are: “Inkjet head CA3 (manufactured by TOSHIBA TEC), temperature 45 ° C, drive voltage 23V, ink height -80mm, frequency 4.8kHz, drop number 7 drop, viscosity 10cP at 45 ° C, surface tension 30mN / m. This is effective from past data in an inkjet head having a configuration such as “discharge ink”. As described above, the continuous ejection is eliminated by changing the image recording position around 10,000 pixels, which is smaller than the continuous number of pixels corresponding to the conveyance direction of the recording medium in which the ink ejection failure occurs. Thus, it is possible to efficiently prevent ink ejection failure due to continuous ejection.

Next, in the above-described inkjet head driving method, the predetermined continuous number N corresponding to the conveyance direction of the recording medium can be set as the pixel continuous number before bubbles are generated in the ink in each nozzle of the inkjet head 52. This continuous number is set from data when bubbles are generated in the past. This is also a characteristic of each head unit, and is measured and determined in advance.
In such a configuration, one cause of ink ejection failure due to continuous ejection is the inclusion of bubbles in the ink liquid retained around the open end of the nozzle. Prior to the occurrence, continuous ejection can be eliminated by changing the image recording position, and ink ejection failure due to continuous ejection can be efficiently prevented.

Further, in the above driving method, the predetermined continuous number T of non-image pixels corresponding to the conveyance direction of the recording medium can be configured to be a time corresponding to before the ink in the nozzle is aggregated or fixed. This is also a characteristic of each head unit, and is measured and determined in advance.
With such a configuration, the ink sticking occurs as described above with respect to the ink sticking due to the evaporation of the solvent in the ink liquid or the aggregation of the components, which is one factor of the ink ejection failure due to the continuous pause of the nozzles. In this case, by changing the image recording position, it is possible to eliminate the continuous pause of the nozzles, and it is possible to efficiently prevent ink ejection failure due to the continuous pause.

  As described above, the head unit position adjusting mechanism 120 selects and sets the use of the nozzles 52a to 52i included in the head unit 52 from the image data, so that nozzles that have not discharged for a certain period of time or discharge for a certain period of time are performed. Instead of other nozzles, ejection or non-ejection can be performed. Thereby, nozzle clogging can be suppressed and high-speed and high-quality image formation can be performed.

  Further, when the head unit 52 can be brought close to the edge of the recording medium S during the processing of the nozzles 52a to 52i by the head unit position adjusting mechanism 120 as described above, a part or all of the head nozzles are used. In some cases, it is possible to set the position where the nozzle can be spited. When the nozzle is changed and set, the requirement for nozzle clogging is comprehensively confirmed by checking that there is no protrusion of the image on the recording medium S. It can also be suppressed.

  As a form of such spitting, as shown in FIGS. 5A and 5B, the head unit 52 has a configuration in which the spitting unit 60 is disposed at a position away from one end of the recording medium S. can do. In the spitting unit 60, for example, as shown in FIG. 5, the spitting tray 62 is provided at a position where the head unit 52 is moved in the lateral position of the recording medium S. With this arrangement, part or all of the head nozzles of the head unit 52 can be spited at a timing at which part or all of the head nozzles can be moved to the spitting tray 62.

Further, the spitting tray 62 can be provided with a suction pump 64 and an ink reservoir 66 connected via the suction pump 64. Then, as described above, at the timing when the head nozzle can be spited, the spitting tray 62 is brought into close contact with the head nozzle, and the ink in the nozzle is positively led out to the ink reservoir 66 by the suction pump 64. You can also.
With such a configuration, ink that tends to remain at the tip of the nozzle can be sucked, and the occurrence of ejection failure can be suppressed.

  Here, the “active energy” referred to in the present invention is not particularly limited as long as it can impart energy capable of generating a starting species in the ink composition by the irradiation, and broadly includes α rays, Including gamma rays, X-rays, ultraviolet rays, visible rays, electron beams, and the like. Among these, from the viewpoints of curing sensitivity and device availability, ultraviolet rays and electron beams are preferable, and ultraviolet rays are particularly preferable. Therefore, the ink composition of the present invention is preferably an ink composition that can be cured by irradiation with ultraviolet rays.

In the active energy curable ink jet recording apparatus of the present invention, the peak wavelength of the active energy is, for example, 200 to 600 nm, preferably 300 to 450 nm, more preferably, depending on the absorption characteristics of the sensitizing dye in the ink composition. Is suitably 350 to 450 nm. In addition, the (a) electron transfer type initiation system of the ink composition of the present invention has sufficient sensitivity even with low output active energy. Therefore, the output of active energy is, for example, 2,000 mJ / cm ² or less, preferably 10 to 2,000 mJ / cm ² , more preferably 20 to 1,000 mJ / cm ² , and still more preferably 50 to 800 mJ. An irradiation energy of / cm ² is appropriate. The active energy exposure surface illuminance (the maximum illuminance of the surface of the recording medium) is, for example, 10 to 2,000 mW / cm ^2, preferably, suitably be irradiated at 20 to 1,000 mW / cm ² is there.
In particular, in the active energy curable ink jet recording apparatus of the present invention, the active energy irradiation has an emission wavelength peak of 390 to 420 nm and a maximum illuminance on the surface of the recording medium of 10 to 1,000 mW / cm ² . It is preferable to irradiate from a light emitting diode that generates ultraviolet rays.

  In the active energy curable ink jet recording apparatus of the present invention, the active energy is applied to the ink composition ejected on the recording medium, for example, for 0.01 to 120 seconds, preferably for 0.1 to 90 seconds. It is appropriate to do.

  Furthermore, in the active energy curable ink jet recording apparatus of the present invention, the ink composition is heated to a constant temperature, and the time from the landing of the ink composition to the recording medium to the irradiation of the active energy is 0.01 to The time is desirably 0.5 seconds, preferably 0.02 to 0.3 seconds, and more preferably 0.03 to 0.15 seconds. Thus, by controlling the time from the landing of the ink composition to the recording medium to the irradiation of the active energy to an extremely short time, it is possible to prevent the landed ink composition from bleeding before curing. .

  In addition, in order to obtain a color image using the active energy curable ink jet recording apparatus of the present invention, it is preferable to superimpose in order from a color with low brightness. By overlapping in this way, the active energy can easily reach the lower ink, and good curing sensitivity, reduction of residual monomers, reduction of odor, and improvement of adhesion can be expected. In addition, although irradiation with active energy can be performed by injecting all the colors and exposing them together, exposure for each color is preferable from the viewpoint of promoting curing.

  Since the ink jet head used in the head unit 52 of the present invention is a piezo ink jet head, a multi-size dot of 1 to 100 pl, preferably 8 to 30 pl, for example, 320 × 320 to 4000 × 4000 dpi, preferably , 400 × 400 to 2400 × 2400 dpi, and can be driven so that it can be emitted. In the present invention, dpi represents the number of dots per 2.54 cm.

  Further, as described above, since the active energy curable ink such as the ink composition of the present invention desirably has a constant temperature for the discharged ink composition, from the ink supply tank to the inkjet head portion, It is preferable to perform temperature control by heat insulation and heating. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

  Further, mercury lamps and gas / solid lasers are mainly used as active energy sources, and mercury lamps and metal halide lamps are widely known as ultraviolet light curable ink jets. Furthermore, replacement with a GaN-based semiconductor ultraviolet light emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long lifetime, high efficiency, and low cost, and are expected as radiation sources for active energy curable ink jets.

  Further, as described above, a light emitting diode (LED) and a laser diode (LD) can be used as the active energy source. In particular, when an ultraviolet light source is required, an ultraviolet LED and an ultraviolet LD can be used. For example, Nichia Corporation has introduced a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. Further, when shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit active energy centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. A particularly preferable active energy source in the present invention is a UV-LED, and a UV-LED having a peak wavelength of 350 to 420 nm is particularly preferable.

  The specific properties of the recording medium that can be used in the present invention will be described below.

[Recording medium]
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and various kinds of non-absorbing resin materials used for ordinary non-coated paper, coated paper, so-called soft packaging, or the like. A resin film formed into a film can be used, and examples of the various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. In addition, examples of the plastic that can be used as the recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals and glasses can also be used as the recording medium.

  In the ink composition of the present invention, when a material with low thermal shrinkage at the time of curing is selected, the adhesive property between the cured ink composition and the recording medium is excellent. Films that tend to curl and deform, such as heat-shrinkable PET film, OPS film, OPP film, ONy film, PVC film, etc., have the advantage that a high-definition image can be formed.

Below, each component used for the ink composition which can be used by this invention is demonstrated sequentially.
[Ink composition]
The ink composition used in the present invention is an ink composition that can be cured by irradiation with active energy, and examples thereof include a cationic polymerization ink composition, a radical polymerization ink composition, and a water-based ink composition. These compositions will be described in detail below.

[Cationically-polymerized ink composition]
The cationic polymerization-based ink composition contains (a) a cationic polymerizable compound, (b) a compound that generates an acid upon irradiation with active energy, and (c) a colorant. If desired, it may further contain an ultraviolet absorber, a sensitizer, an antioxidant, an antifading agent, a conductive salt, a solvent, a polymer compound, a surfactant and the like.
Hereafter, each component used for a cationic polymerization type ink composition is demonstrated one by one.

[(A) Cationic polymerizable compound]
The (a) cationic polymerizable compound used in the present invention is not particularly limited as long as it is a compound that causes a polymerization reaction by an acid generated from a compound that generates an acid by irradiation of active energy (b) described later and cures. Various known cationic polymerizable monomers known as photo cationic polymerizable monomers can be used. Examples of the cationic polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

Examples of the epoxy compound include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides.
Aromatic epoxides include di- or polyglycidyl ethers produced by the reaction of polyphenols having at least one aromatic nucleus or their alkylene oxide adducts and epichlorohydrin, such as bisphenol A or its alkylene oxides. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or alkylene oxide adducts thereof, and novolak type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxide, cyclohexene oxide obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Or a cyclopentene oxide containing compound is mentioned preferably.

  Examples of the aliphatic epoxide include dihydric polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Typical examples include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, di- or tri- or di- or tri-glycol or adducts thereof. Polyglycidyl ether of polyhydric alcohol such as glycidyl ether, diglycidyl ether of polyethylene glycol or alkylene oxide adduct thereof, diglycidyl ether of polyalkylene glycol represented by diglycidyl ether of polypropylene glycol or alkylene oxide adduct thereof, etc. Can be mentioned. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

The epoxy compound may be monofunctional or polyfunctional.
Examples of monofunctional epoxy compounds that can be used in the present invention include, for example, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, 3 -Vinylcyclohexene oxide etc. are mentioned.

  Examples of polyfunctional epoxy compounds include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, and brominated bisphenol. S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxy 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxycyclo) Xylmethyl) adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ′, 4′-epoxy-6 '-Methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylenebis (3,4-epoxycyclohexanecarboxylate) , Epoxyhexahydrophthalate dioctyl, epoxyhexahydrophthalate di-2-ethylhexyl, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether Glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1,2,7,8- Examples include diepoxyoctane and 1,2,5,6-diepoxycyclooctane.

  Among these epoxy compounds, aromatic epoxides and alicyclic epoxides are preferable from the viewpoint of excellent curing speed, and alicyclic epoxides are particularly preferable.

  Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

The vinyl ether compound may be monofunctional or polyfunctional.
Specifically, examples of monofunctional vinyl ethers include, for example, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, Cyclohexylmethyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether , Methoxypolyethyleneglycol Vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, Examples thereof include chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether and the like.

  Examples of polyfunctional vinyl ethers include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, and bisphenol F. Divinyl ethers such as alkylene oxide divinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol Hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide addition Examples thereof include polyfunctional vinyl ethers such as pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

  As the vinyl ether compound, a di- or trivinyl ether compound is preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and a divinyl ether compound is particularly preferable.

The oxetane compound in the present invention refers to a compound having an oxetane ring, and a known oxetane compound can be arbitrarily selected and used as described in JP-A Nos. 2001-220526, 2001-310937, and 2003-341217. .
The compound having an oxetane ring that can be used in the ink composition of the present invention is preferably a compound having 1 to 4 oxetane rings in the structure. By using such a compound, it becomes easy to maintain the viscosity of the ink composition within a good handling range, and obtain high adhesion between the cured ink composition and the recording medium. Can do.

The compound having such an oxetane ring is described in detail in the above-mentioned JP-A No. 2003-341217, paragraph numbers [0021] to [0084], and the compounds described therein can be suitably used in the present invention.
Among the oxetane compounds used in the present invention, it is preferable to use a compound having one oxetane ring from the viewpoint of the viscosity and tackiness of the ink composition.

In the ink composition of the present invention, these cationic polymerizable compounds may be used alone or in combination of two or more, but from the viewpoint of effectively suppressing shrinkage during ink curing. Is preferably a combination of at least one compound selected from an oxetane compound and an epoxy compound and a vinyl ether compound.
The content of the (a) cationic polymerizable compound in the ink composition is suitably 10 to 95% by mass, preferably 30 to 90% by mass, and more preferably 50 to 85%, based on the total solid content of the composition. It is the range of mass%.

[(B) Compound that generates acid upon irradiation with active energy]
The ink composition of the present invention contains a compound that generates an acid upon irradiation with radiation (hereinafter, appropriately referred to as “photoacid generator”).
Examples of the photoacid generator that can be used in the present invention include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, and light used for microresists. (400-200 nm ultraviolet rays, far ultraviolet rays, particularly preferably g-line, h-line, i-line, KrF excimer laser beam), ArF excimer laser beam, electron beam, X-ray, molecular beam, ion beam, etc. A compound capable of generating can be appropriately selected and used.

  Examples of such a photoacid generator include an onium salt such as a diazonium salt, an ammonium salt, a phosphonium salt, an iodonium salt, a sulfonium salt, a selenonium salt, an arsonium salt, or the like, which decomposes upon irradiation with radiation to generate an acid. Halogen compounds, organometallic / organic halides, photoacid generators having o-nitrobenzyl type protecting groups, compounds that generate sulfonic acids by photolysis, such as iminosulfonates, disulfone compounds, diazoketosulfones And diazodisulfone compounds.

  As the photoacid generator, oxazole derivatives and s-triazine derivatives described in JP-A No. 2002-122994, paragraphs [0029] to [0030] are also preferably used. Furthermore, onium salt compounds and sulfonate compounds exemplified in JP-A No. 2002-122994, paragraph numbers [0037] to [0063] can also be suitably used as the photoacid generator in the present invention.

(B) A photo-acid generator can be used individually by 1 type or in combination of 2 or more types.
The content of the (b) photoacid generator in the ink composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably in terms of the total solid content of the ink composition. Is 1-7 mass%.

  In the ink composition of the present invention, various additives can be used in combination with the essential components according to the purpose. These optional components will be described.

[(C) Colorant]
The ink composition of the present invention can form a visible image by adding a colorant. For example, when forming an image area of a lithographic printing plate, it is not always necessary to add it, but it is also preferable to use a colorant from the viewpoint of plate inspection of the obtained lithographic printing plate.
There is no restriction | limiting in particular in the coloring agent which can be used here, According to a use, well-known various color materials and (pigment, dye) can be selected suitably, and can be used. For example, when forming an image excellent in weather resistance, a pigment is preferable. As the dye, both water-soluble dyes and oil-soluble dyes can be used, but oil-soluble dyes are preferred.

[Pigment]
The pigment preferably used in the present invention will be described.
The pigment is not particularly limited, and all commercially available organic and inorganic pigments or pigments dispersed in an insoluble resin or the like as a dispersion medium, or the resin is grafted onto the pigment surface Can be used. Moreover, what dye | stained the resin particle with dye can be used.
Examples of these pigments include, for example, “Pigment Dictionary” (2000), edited by Seijiro Ito. Herbst, K.M. Hunger “Industrial Organic Pigments”, JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, and JP 2003-342503 A3.

  Specific examples of organic pigments and inorganic pigments that can be used in the present invention include C.I. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Non-benzidine type azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  C. As a thing which exhibits red or magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G ′ Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

  As a pigment exhibiting blue or cyan, C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Phthalocyanine pigments such as C.I. Pigment Blue 15 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

As a pigment exhibiting green, C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. And azo metal complex pigments such as CI Pigment Green 8 (Nitroso Green).
As a pigment exhibiting an orange color, C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. And anthraquinone pigments such as CI Pigment Orange 51 (dichloropyrantron orange).

Examples of the black pigment include carbon black, titanium black, and aniline black.
Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) or the like can be used.

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a large hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

For dispersing the pigment, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, or a wet jet mill is used. be able to.
It is also possible to add a dispersant when dispersing the pigment. Examples of the dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a high molecular weight unsaturated acid ester, a high molecular copolymer, a modified polyacrylate, an aliphatic Examples thereof include polyvalent carboxylic acids, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, and pigment derivatives. It is also preferable to use a commercially available polymer dispersant such as the Solsperse series from Zeneca.
Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  In the ink composition, as a dispersion medium for various components such as pigments, a solvent may be added, or the solvent-free low molecular weight component (a) cationic polymerizable compound may be used as a dispersion medium. However, the ink composition of the present invention is a radiation curable ink, and is preferably solventless in order to cure the ink after it is applied to a recording medium. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a problem of VOC (Volatile Organic Compound) of the remaining solvent occurs. From such a viewpoint, as the dispersion medium, (a) a cationically polymerizable compound is used, and among them, it is preferable to select a cationically polymerizable monomer having the lowest viscosity in terms of dispersion suitability and handling properties of the ink composition. .

The average particle size of the pigment is preferably 0.02 to 4 μm, more preferably 0.02 to 2 μm, and more preferably 0.02 to 1.0 μm.
Selection of pigments, dispersants, and dispersion media, dispersion conditions, and filtration conditions are set so that the average particle diameter of the pigment particles falls within the above preferred range. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

〔dye〕
The dye used in the present invention is preferably oil-soluble. Specifically, it means that the solubility in water at 25 ° C. (the mass of the dye dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Accordingly, so-called water-insoluble oil-soluble dyes are preferably used.

The dye used in the present invention preferably has an oil-solubilizing group introduced into the above-described dye mother core in order to dissolve the necessary amount in the ink composition.
As the oil-solubilizing group, long chain, branched alkyl group, long chain, branched alkoxy group, long chain, branched alkylthio group, long chain, branched alkylsulfonyl group, long chain, branched acyloxy group, long chain, branched alkoxycarbonyl group, Long chain, branched acyl group, long chain, branched acylamino group long chain, branched alkylsulfonylamino group, long chain, branched alkylaminosulfonyl group and these long chains, aryl groups containing branched substituents, aryloxy groups, aryloxycarbonyl Group, arylcarbonyloxy group, arylaminocarbonyl group, arylaminosulfonyl group, arylsulfonylamino group and the like.
In addition, for water-soluble dyes having carboxylic acid and sulfonic acid, long chain, branched alcohol, amine, phenol, aniline derivatives are used as oil-solubilizing alkoxycarbonyl groups, aryloxycarbonyl groups, alkylaminosulfonyl groups, A dye may be obtained by conversion to an arylaminosulfonyl group.

The oil-soluble dye preferably has a melting point of 200 ° C. or lower, more preferably has a melting point of 150 ° C. or lower, and still more preferably has a melting point of 100 ° C. or lower. By using an oil-soluble dye having a low melting point, the precipitation of dye crystals in the ink composition is suppressed, and the storage stability of the ink composition is improved.
Further, it is desirable that the oxidation potential is noble (high) in order to improve fading, particularly resistance to oxidizing substances such as ozone and curing characteristics. For this reason, as the oil-soluble dye used in the present invention, those having an oxidation potential of 1.0 V (vs SCE) or more are preferably used. The oxidation potential is preferably higher, the oxidation potential is more preferably 1.1 V (vs SCE) or more, and particularly preferably 1.15 V (vs SCE) or more.

As the yellow dye, a compound having a structure represented by the general formula (Y-I) described in JP-A No. 2004-250483 is preferable.
Particularly preferred dyes are dyes represented by the general formulas (Y-II) to (Y-IV) described in paragraph [0034] of JP-A No. 2004-250483. And the compounds described in paragraphs [0060] to [0071] of JP-A-250483. The oil-soluble dye of the general formula (Y-I) described in the publication may be used not only for yellow but also for inks of any color such as black ink and red ink.

The magenta dye is preferably a compound having a structure represented by the general formulas (3) and (4) described in JP-A No. 2002-114930. Specific examples include paragraphs of JP-A No. 2002-114930. Examples include the compounds described in [0054] to [0073].
Particularly preferred dyes are azo dyes represented by the general formulas (M-1) to (M-2) described in paragraph numbers [0084] to [0122] of JP-A No. 2002-121414, and specific examples Examples thereof include compounds described in paragraph numbers [0123] to [0132] of JP-A No. 2002-121414. The oil-soluble dyes represented by the general formulas (3), (4) and (M-1) to (M-2) described in the publication are used not only for magenta but also for any color ink such as black ink and red ink. May be.

Examples of cyan dyes include dyes represented by formulas (I) to (IV) described in JP-A No. 2001-181547, and paragraphs [0063] to [0078] of JP-A No. 2002-121414. The dyes represented by the general formulas (IV-1) to (IV-4) are listed as preferable examples, and specific examples include paragraph numbers [0052] to [0066] in JP-A No. 2001-181547. Examples thereof include the compounds described in paragraph Nos. [0079] to [0081] of Kai 2002-121414.
Particularly preferred dyes are phthalocyanine dyes represented by general formulas (CI) and (C-II) described in paragraphs [0133] to [0196] of JP-A No. 2002-121414, A phthalocyanine dye represented by formula (C-II) is preferred. Specific examples thereof include the compounds described in JP-A No. 2002-121414, paragraph numbers [0198] to [0201]. The oil-soluble dyes of the formulas (I) to (IV), (IV-1) to (IV-4), (CI) and (C-II) are not only cyan but also black ink or green ink. The ink may be used for any color ink.

  These colorants are preferably added in an amount of 1 to 20% by mass in terms of solid content in the ink composition, and more preferably 2 to 10% by mass.

[Other ingredients]
The various additives used as necessary are described below.
[Ultraviolet absorber]
In the present invention, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image and preventing discoloration.
Examples of the ultraviolet absorber are described in JP-A-58-185679, JP-A-61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Benzotriazole compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194843, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492 and 56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in No. 24239, compounds that emit ultraviolet light by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, so-called fluorescent brighteners, and the like.
Although the addition amount is appropriately selected according to the purpose, it is generally about 0.5 to 15% by mass in terms of solid content.

[Sensitizer]
If necessary, a sensitizer may be added to the ink composition of the present invention for the purpose of improving the acid generation efficiency of the photoacid generator and increasing the photosensitive wavelength. Any sensitizer may be used as long as the photoacid generator is sensitized by an electron transfer mechanism or an energy transfer mechanism. Preferably, aromatic polycondensed compounds such as anthracene, 9,10-dialkoxyanthracene, pyrene and perylene, aromatic ketone compounds such as acetophenone, benzophenone, thioxanthone and Michlerketone, and heterocyclic compounds such as phenothiazine and N-aryloxazolidinone Is mentioned. The addition amount is appropriately selected according to the purpose, but is generally 0.01 to 1 mol%, preferably 0.1 to 0.5 mol%, based on the photoacid generator.

〔Antioxidant〕
An antioxidant can be added to improve the stability of the ink composition. Examples of the antioxidant include European published patents, 223739, 309401, 309402, 310551, 310552, 359416, and 3435443. JP, 54-85535, 62-262417, 63-113536, 63-163351, JP-A-2-262654, JP-A-2-71262, Examples thereof include those described in Kaihei 3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.1 to 8% by mass in terms of solid content.

[Anti-fading agent]
In the ink composition of the present invention, various organic and metal complex anti-fading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the metal complex anti-fading agent include nickel complexes and zinc complexes. No. 17643, VII, I to J, No. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .
The addition amount is appropriately selected according to the purpose, but is generally about 0.1 to 8% by mass in terms of solid content.

[Conductive salts]
Conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, and dimethylamine hydrochloride can be added to the ink composition of the present invention for the purpose of controlling ejection properties.

〔solvent〕
In order to improve the adhesion to the recording medium, it is also effective to add a very small amount of an organic solvent to the ink composition of the present invention.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone, alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol, and chlorine such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, glycols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether And ether solvents.
In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC, and the amount is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass with respect to the whole ink composition. % Range.

[Polymer compound]
Various polymer compounds can be added to the ink composition of the present invention in order to adjust film physical properties. Examples of polymer compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, a copolymer containing “carboxyl group-containing monomer”, “methacrylic acid alkyl ester”, or “acrylic acid alkyl ester” as a structural unit is also preferably used as the copolymer composition of the polymer binder.

[Surfactant]
A surfactant may be added to the ink composition of the present invention.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.

In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to inhibit the adhesion to recording media such as polyolefin and PET, and the like, The tackifier which does not do can be contained.
As a tackifier, specifically, a high molecular weight adhesive polymer (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms) described in JP-A-2001-49200, 5-6p. An ester with an alcohol having, an ester of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms) Or a low molecular weight tackifying resin having a polymerizable unsaturated bond.

[Preferred physical properties of ink composition]
The ink composition of the present invention preferably has an ink viscosity of 7 to 30 mPa · s, more preferably 7 to 20 mPa · s at the temperature at the time of ejection in consideration of ejection properties, and is in the above range. It is preferable to adjust the composition ratio appropriately. The ink viscosity at 25 to 30 ° C. is 35 to 500 mPa · s, preferably 35 to 200 mPa · s. By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be prevented, uncured monomer can be reduced, and odor can be reduced. Dot bleeding at the time of landing can be suppressed, and as a result, the image quality is improved. If the ink viscosity at 25 to 30 ° C. is less than 35 mPa · s, the effect of preventing bleeding is small, and conversely if it is greater than 500 mPa · s, there is a problem in the delivery of the ink liquid.

  The surface tension of the ink composition of the present invention is preferably 20 to 40 mN / m, more preferably 25 to 35 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and uncoated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and 40 mN / m or less is preferable in terms of wettability.

The ink composition of the present invention thus adjusted is suitably used as an ink for inkjet recording. When used as an ink for ink jet recording, the ink composition is ejected onto a recording medium by an ink jet printer, and then the ejected ink composition is irradiated with radiation and cured to perform recording.
In the printed matter obtained with this ink, the image portion is cured by irradiation with radiation such as ultraviolet rays, and the strength of the image portion is excellent. Therefore, in addition to image formation with ink, for example, an ink receiving layer (image image of a lithographic printing plate) Part), and can be used for various purposes.

[Radical polymerization ink composition]
The radical polymerization ink composition contains (d) a radical polymerizable compound, (e) a polymerization initiator, and (f) a colorant. If desired, it may further contain a sensitizing dye, a co-sensitizer, and the like.
Hereinafter, each component used for the radical polymerization ink composition will be sequentially described.

(D) [Radically polymerizable compound]
Examples of the radically polymerizable compound include compounds having an ethylenically unsaturated bond capable of addition polymerization as described below.

[Compound having an ethylenically unsaturated bond capable of addition polymerization]
Examples of compounds having addition-polymerizable ethylenically unsaturated bonds that can be used in the ink composition of the present invention include unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid Etc.) and an aliphatic polyhydric alcohol compound, an amide of the unsaturated carboxylic acid and an aliphatic polyamine compound, and the like.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol di Acrylate, Tetraethylene glycol diacrylate, Pentaerythritol diacrylate, Pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (acryloxyethoxy) phenyl] dimethylmethane. Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate Sorbitol tetritaconate, etc.

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate. Furthermore, the mixture of the above-mentioned ester monomer can also be mention | raise | lifted. Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexa. Examples include methylene bis-methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide.

As another example, a vinyl compound containing a hydroxyl group represented by the following general formula (A) is added to a polyisocyanate compound having two or more isocyanate groups per molecule described in JP-B-48-41708. Examples thereof include vinyl urethane compounds containing two or more polymerizable vinyl groups in one molecule to which a monomer is added.
_{CH 2 = C (R) COOCH} 2 CH (R ') OH (A)
(However, R and R ′ represent H or CH _3. )
Further, as described in JP-A-51-37193, urethane acrylates, JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, etc. Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid can be used. Furthermore, Journal of Japan Adhesion Association vol.20, No. 7, pages 300 to 308 (1984) as photocurable monomers and oligomers can also be used. In the present invention, these monomers may be used in a chemical form such as a prepolymer, that is, a dimer, a trimer and an oligomer, or a mixture thereof and a copolymer thereof.

  The amount of the radical polymerizable compound used is usually 1 to 99.99%, preferably 5 to 90.0%, more preferably 10 to 70% with respect to all the components of the ink composition (where% is used herein) Mass%).

(E) [Polymerization initiator]
Next, the polymerization initiator used in the radical polymerization ink composition of the present invention will be described.
The polymerization initiator in the present invention is a compound that undergoes a chemical change through the action of light or the interaction with the electronically excited state of a sensitizing dye to generate at least one of radicals, acids, and bases. is there.

Preferred polymerization initiators include (I) aromatic ketones, (II) aromatic onium salt compounds, (III) organic peroxides, (IV) hexaarylbiimidazole compounds, (V) ketoxime ester compounds, (VI ) Borate compounds, (VII) azinium compounds, (VIII) metallocene compounds, (IX) active ester compounds, (X) compounds having a carbon halogen bond, and the like.
(F) Colorant The same as described in (c) can be used.

[Sensitizing dye]
In the present invention, a sensitizing dye may be added for the purpose of improving the sensitivity of the photopolymerization initiator. Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines ( For example, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, squalium) ), Coumarins (eg 7-diethylamino-4-methylcoumarin).

[Co-sensitizer]
Further, the ink of the present invention may contain a known compound having a function of further improving sensitivity or suppressing polymerization inhibition by oxygen as a co-sensitizer.

  Examples of such co-sensitizers include amines such as MR Sander et al., “Journal of Polymer Society”, Vol. 10, page 3173 (1972), Japanese Examined Patent Publication No. 44-20189, Japanese Patent Laid-Open No. 51-82102. Publication, JP 52-134692, JP 59-138205, JP 60-84305, JP 62-18537, JP 64-33104, Research Disclosure 33825 Specifically, triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like can be mentioned.

  Other examples include thiols and sulfides, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, and JP-A-56-75643. Specific examples include disulfide compounds, and specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene, and the like.

  Other examples include amino acid compounds (eg, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (eg, tributyltin acetate), and hydrogen described in Japanese Patent Publication No. 55-34414. Donors, sulfur compounds described in JP-A-6-308727 (eg, trithiane), phosphorus compounds described in JP-A-6-250387 (diethylphosphite, etc.), Si-- described in Japanese Patent Application No. 6-191605 H, Ge-H compound, etc. are mentioned.

  Moreover, it is preferable to add 200-20000 ppm of a polymerization inhibitor from a viewpoint of improving storability. The ink for ink jet recording of the present invention is preferably ejected by heating and lowering the viscosity in the range of 40 to 80 ° C., and a polymerization inhibitor is preferably added to prevent clogging of the head due to thermal polymerization. Examples of the polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cuperon Al.

[Others]
In addition, known compounds can be used as necessary. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins. Resin, rubber resin, wax and the like can be appropriately selected and used. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to contain a tackifier that does not inhibit the polymerization. Specifically, high molecular weight adhesive polymers described in JP-A-2001-49200, 5-6p (for example, esters of (meth) acrylic acid and alcohols having an alkyl group having 1 to 20 carbon atoms) , An ester of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer formed of an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms), A low molecular weight tackifying resin having a saturated bond.

  It is also effective to add a trace amount of organic solvent in order to improve the adhesion to the recording medium. In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC. % Range.

  In addition, as a means for preventing a decrease in sensitivity due to the light-shielding effect of the ink color material, it is also preferable to combine a cationic polymerizable monomer having a long polymerization initiator lifetime with a polymerization initiator to obtain a radical-cation hybrid type curable ink. One.

[Water-based ink composition]
The aqueous ink composition contains a polymerizable compound and a water-soluble photopolymerization initiator that generates radicals by the action of radiation. If desired, it may further contain a coloring material and the like.

[Polymerizable compound]
As the polymerizable compound contained in the aqueous ink composition of the present invention, a polymerizable compound contained in a known aqueous ink composition can be used.
A reactive material can be added to the water-based ink composition in order to optimize the formulation considering end-user characteristics such as curing speed, adhesion, and flexibility. Examples of such reactive materials include (meth) acrylate (ie, acrylate and / or methacrylate) monomers and oligomers, epoxides, and oxetanes.
Examples of acrylate monomers include phenoxyethyl acrylate, octyl decyl acrylate, tetrahydrofuryl acrylate, isobornyl acrylate, hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate (e.g., tetraethylene glycol). Diacrylate), dipropylene glycol diacrylate, tri (propylene glycol) triacrylate, neopentyl glycol diacrylate, bis (pentaerythritol) hexaacrylate, ethoxylated or propoxylated glycol and polyol acrylate (e.g. propoxylated neopentyl glycol Diacrylate, ethoxylated trimethylol proppant Acrylate), and mixtures thereof.
Examples of acrylate oligomers include ethoxylated polyethylene glycol, ethoxylated trimethylolpropane acrylate and polyether acrylate and ethoxylates thereof, and urethane acrylate oligomers.
Examples of methacrylates include hexanediol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and mixtures thereof.
The amount of oligomer added is preferably 1 to 80% by weight, more preferably 1 to 10% by weight, based on the total weight of the ink composition.

[Water-soluble photopolymerization initiator that generates radicals by the action of active energy]
The polymerization initiator that can be used in the ink composition of the invention will be described. As an example, for example, a photopolymerization initiator having a wavelength of up to about 400 nm may be mentioned. As such a photopolymerization initiator, for example, a photopolymerization initiator represented by the following general formula (hereinafter referred to as TX), which is a substance having functionality in a long wavelength region, that is, a sensitivity to generate a radical upon receiving ultraviolet rays. In the present invention, it is particularly preferable to select and use them appropriately.

In the above general formulas TX-1 to TX-3, R2 represents — (CH ₂ ) _x — (x = 0 or 1), —O— (CH ₂ ) _y — (y = 1 or 2), substituted or unsubstituted Represents a phenylene group. When R2 is a phenylene group, at least one hydrogen atom in the benzene ring is, for example, a carboxyl group or a salt thereof, a sulfonic acid or a salt thereof, a linear or branched alkyl having 1 to 4 carbon atoms. May be substituted with one or more groups or atoms selected from a group, a halogen atom (fluorine, chlorine, bromine, etc.), an alkoxyl group having 1 to 4 carbon atoms, an aryloxy group such as a phenoxy group, and the like. . M represents a hydrogen atom or an alkali metal (for example, Li, Na, K, etc.). R3 and R4 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group. Examples of the alkyl group include, for example, a linear or branched alkyl group having about 1 to 10 carbon atoms, particularly about 1 to 3 carbon atoms. Moreover, as an example of the substituent of these alkyl groups, a halogen atom (a fluorine atom, a chlorine atom, an oxalic atom etc.), a hydroxyl group, an alkoxyl group (C1-C3 grade) etc. are mentioned, for example. M represents an integer of 1 to 10.

  Furthermore, in the present invention, a water-soluble derivative (hereinafter abbreviated as IC system) of a photopolymerization initiator Irgacure 2959 (trade name: manufactured by Ciba Specialty Chemicals) having the following general formula may be used. Specifically, IC-1 to IC-3 having the following formulas can be used.

[Prescription for clear ink]
The above-mentioned water-soluble polymerizable compound can be made into a clear ink by making it into the form of a transparent water-based ink without containing the above-mentioned coloring material. In particular, if it is prepared so as to have ink jet recording characteristics, a clear ink for water-based photocurable ink jet recording can be obtained. If such an ink is used, a clear film can be obtained because it does not contain a color material. Clear inks that do not contain color materials can be used for undercoats to give recording materials suitable for image printing, or for surface protection of images formed with ordinary inks, further decoration and gloss For example, it may be used for an overcoat for the purpose of application. In the clear ink, colorless pigments or fine particles that are not intended for coloring can be dispersed and contained according to these applications. By adding these, it is possible to improve various properties such as image quality, fastness, and workability (handling property) of the printed matter in both the undercoat and the overcoat.

  Prescription conditions for application to such a clear ink include 10 to 85% of a water-soluble polymerizable compound as a main component of the ink, a photopolymerization initiator (for example, an ultraviolet polymerization catalyst), and the above water-soluble polymerization. It is preferable to prepare such that 1 to 10 parts by mass with respect to 100 parts by mass of the organic compound and at least 0.5 part of the photopolymerization initiator is simultaneously contained with respect to 100 parts of ink.

[Material composition of colorant-containing ink]
When the water-soluble polymerizable compound described above is used for an ink containing a coloring material, the concentration of the polymerization initiator and the polymerizable substance in the ink should be adjusted according to the absorption characteristics of the contained coloring material. Is preferred. As described above, the amount of water or solvent is in the range of 40% to 90%, preferably in the range of 60% to 75%, based on mass, as the blending amount. Furthermore, the content of the polymerizable compound in the ink is in the range of 1% to 30%, preferably in the range of 5% to 20%, based on the mass, with respect to the total amount of the ink. The polymerization initiator depends on the content of the polymerizable compound, but is generally in the range of 0.1 to 7%, preferably 0.3 to 5% on the mass basis with respect to the total amount of the ink.

  When a pigment is used as the color material of the ink, the concentration of the pure pigment in the ink is generally in the range of 0.3% by mass to 10% by mass with respect to the total amount of the ink. The coloring power of the pigment depends on the dispersion state of the pigment particles, but if it is in the range of about 0.3 to 1%, it becomes a range used as a light-colored ink. On the other hand, if it is more than that, it gives a concentration used for general color coloring.

Comparative example

Next, a comparative example will be described.
In the comparative examples, the following articles and conditions were employed, and the results of the tack-free test when the UV light of each energy was irradiated were compared.
Ink: UV curable ink in general Head unit: CA3 manufactured by TOSHIBA TEC Capable of multi-drop ejection Resolution: 150 dpi
Image size: Conveyance direction length 100mm, width 50mm

  As a result of the comparative example, it has been found that, in the conventional normal drawing in which the nozzle is not changed while the head unit is stationary, ejection failure occurs in 512.4 sheets.

  Next, examples carried out to confirm the operational effects of the active energy curable ink jet recording apparatus of the present invention will be described. In addition, the present Example was performed on the same conditions as the comparative example mentioned above.

  As a result of the examples, it has been found that in any case, the interval at which nozzle clogging occurs is sufficiently long compared to the comparative example, and printing can be performed without problems. Thus, it can be seen that an image free from nozzle clogging can be formed by judging the use status of the nozzle and selecting and setting the nozzle.

1 is a schematic configuration diagram of an embodiment of an active energy curable ink jet recording apparatus for performing an active energy curable ink jet recording method according to the present invention. FIG. 2 is an enlarged perspective view of an image recording unit by an ink jet head in the active energy curable ink jet recording apparatus shown in FIG. 1. The block diagram of the head driver as a control part which controls an inkjet head in the active energy curing type inkjet recording device shown in FIG. FIG. 6 is an external perspective view showing another form of scanning conveyance of a recording medium according to the present invention. (A) is a plan view of the head unit position adjusting mechanism in the image recording unit at the first position, and (b) is a plan view of the head unit position adjusting mechanism in the image recording unit at the second position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Active energy curable inkjet recording device 12 Housing | casing S Recording medium 20 Recording medium accommodating part 30 Conveying part 40 Scanning conveying part 50 Image recording part 70 Cartridge mounting part 80 Exhaust cooling part 90 Tray 42 Conveying belt 42P Image recording position 52 Head units 52a, 52b, 52c, 52d, 52e, 52f, 52g, 52h, 52i Nozzle 54 Head driver 56 Ultraviolet irradiation unit 120 Head unit position adjustment mechanism 122 Head unit drive control device

Claims (7)

A full-line type ink jet head drive device comprising droplet discharge nozzles arranged in the entire width direction of a recording medium,
Head driving means for controlling droplet ejection of the inkjet head based on the recording image data;
Image data analysis means for calculating an image portion in which a pixel that is an image or a pixel that is a non-image is a predetermined continuous number from the recording image data corresponding to the conveyance direction of the recording medium;
A head unit position adjusting mechanism for moving the inkjet head in the recording medium width direction that is orthogonal to the recording medium conveyance around a predetermined number of consecutive pixels calculated by the image data analysis means;
An inkjet head drive device comprising:   2. The activity according to claim 1, wherein the head unit position adjusting mechanism sets a head moving position for moving at least a part of the head nozzle by moving the ink jet head from the recording medium position in the recording medium width direction. Energy curable inkjet drive.   The inkjet head driving device according to claim 1, wherein the predetermined number of continuous pixels is 10,000. A full-line type inkjet head driving method comprising droplet discharge nozzles arranged in the entire width direction of a recording medium,
An image portion in which a pixel that is an image or a pixel that is not an image has a predetermined continuous number is calculated from the recording image data corresponding to the conveyance direction of the recording medium, and the head unit is around the predetermined continuous number of the calculated pixels. An ink jet driving method of moving the ink jet head in a recording medium width direction which is a direction orthogonal to the recording medium conveyance by a position adjusting mechanism.   The inkjet head driving method according to claim 4, wherein the predetermined continuous number of pixels is a number corresponding to the pre-measured bubble generation before the ink in the nozzle.   The inkjet head driving method according to claim 4, wherein the predetermined continuous number of pixels is a number corresponding to the pre-measured occurrence of sticking of the ink in the nozzle.   The ink jet head driving method according to claim 4, wherein the predetermined number of continuous pixels corresponds to the vicinity of 5 minutes in the non-ejection time of the nozzle.

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