JP2007083509A - Photo-curing type inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo-curing type inkjet recorder which removes smell brought about from ink at no cost, and is friendly to an environment with odor peculiar to ozone eliminated. <P>SOLUTION: In the photo-curing type inkjet recorder 10 which has an ultraviolet energy irradiating means 12, an inkjet head 11 that delivers an ink I curable by ultraviolet energy irradiated by the ultraviolet energy irradiating means 12 toward a recording medium S on the basis of an image signal, and a recording medium conveying means which conveys the recording medium S to a position opposed to the inkjet head 11, an ozone deodorizing means 13 which deodorizes the smell brought out from the ink by the ozone generated by the ultraviolet irradiating means 12 is set in the immediate vicinity of the downstream side of the ultraviolet irradiating means 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photocurable inkjet recording apparatus that forms an image on a recording medium by inkjet using an ink that is cured by light energy such as ultraviolet rays.

  An inkjet apparatus that forms an image by ejecting ink that is cured by energy such as ultraviolet rays onto a recording medium using an inkjet head, and curing the ink by energy irradiation, can be recorded on various recording media at high speed. In addition, it has a feature such that a high-definition image can be obtained with little bleeding. In particular, an apparatus using an ultraviolet curable ink has been developed from the viewpoint of easy handling of a light source and compactness.

On the other hand, since it is difficult to eject high-viscosity inks, inkjet heads are driven by heating the heads to lower the ink viscosity during drawing. Ink containing is used.
Therefore, the ink has an odor, and this volatile component has a problem because it may cause discomfort to the human body. Therefore, development of an ink with less odor has been attempted, but a product with high cost and satisfactory characteristics has not yet been obtained.

In addition, in electrostatic ink jet recording, ink can be properly discharged even with a low driving voltage, and even when continuous recording is performed at high speed, charged particle concentration and ink jet recording with stable discharge state can be performed. As described above, it has been known to include ozone removing means for removing ozone inside the recording apparatus from the vicinity of the ink jet head. However, the odor from the ink remained neglected.
JP 2005-096207 A

  The present invention has been made to solve such problems, and captures and decomposes the generated ink volatile components to eliminate odors, eliminates odors peculiar to ozone, and has excellent productivity and high image quality. An object of the present invention is to provide a photocurable ink jet apparatus capable of performing simple drawing.

In order to solve the above-mentioned problems, the invention described in claim 1 relates to a photo-curable ink jet recording apparatus, wherein an ultraviolet energy irradiating means and an ink that can be cured by the ultraviolet energy irradiated by the ultraviolet energy irradiating means are used as an image signal. Generated by the ultraviolet irradiation means in a photocurable inkjet recording apparatus having an inkjet head that discharges toward a recording medium based on the recording medium, and a recording medium conveyance unit that conveys the recording medium to a position facing the inkjet head Ozone deodorizing means for collecting ozone is provided, and the odor generated from the ink is introduced into the ozone deodorizing means, whereby the ink odor is deodorized in the ozone deodorizing means.
According to a second aspect of the present invention, there is provided the photocurable ink jet recording apparatus according to the first aspect, wherein the cooling air that flows over the discharged ink passes through the ozone deodorizing means. It is characterized by providing.
According to a third aspect of the present invention, in the photocurable ink jet recording apparatus according to the second aspect, the air that has passed through the ozone deodorizing means is exhausted outside the apparatus.
According to a fourth aspect of the present invention, there is provided the photocurable ink jet recording apparatus according to the third aspect, wherein an activated carbon filter is provided at an external outlet for exhausting air that has passed through the ozone deodorizing means to the outside. It is a feature.

  By configuring as described above, the odor generated from the ink is deodorized by using the ozone generated by the ultraviolet irradiation means effectively (waste) without using an ozone generator, so there is no cost. In addition, it is possible to obtain an environmentally friendly photo-curable ink jet recording apparatus in which the smell peculiar to ozone is eliminated by the oxidation reaction.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a principle diagram of ozone deodorization according to the present invention in a photocurable ink jet recording apparatus.
In the figure, 10 is a photocurable ink jet recording apparatus according to the present invention, and the conventional apparatus is an ink jet head 11 that discharges an ultraviolet curable ink I onto a recording medium S, and an ink downstream of the ink jet head 11 in the recording medium conveyance direction. An ultraviolet light source 12 for curing is disposed to give light energy for curing the ink I ejected onto the recording medium S.
In the present invention, an ozone deodorizing device 13 is further provided downstream of the ultraviolet light source 12 for ink curing. Since the ultraviolet light source 12 for curing ink contains short waves, ozone is inevitably generated during use, and this ozone is collected in the ozone deodorizer 13 by the cooling fan of the ultraviolet light source 12 (see FIG. 2), and The principle of the present invention is that deodorization is carried out by the oxidizing action of ozone O3 by introducing the evaporated odor generated from the ink.

Next, the material, configuration, and function of the ozone deodorizer 13 will be described.
The ozone deodorizing device 13 is an oxide or metal of Mn, Ag, Fe, Co, Zn, Ni, Pt, Pd, Rh on at least one carrier from the group consisting of silica, alumina, zirconia, titania, zeolite and activated carbon. An adsorption cracking catalyst carrying at least one of the above has a honeycomb shape. The honeycomb shape is preferably 250 to 550 cells / 10 cm ² .

  The coated type in which the base material is coated with a catalyst, or the integrally formed type in which only the catalyst is integrally formed into a honeycomb shape may be used, and the shape of each cell in the honeycomb shape is not particularly limited. Any shape such as a lattice shape, a triangular shape, a hexagonal shape, or a corrugated shape may be used. Furthermore, the shape is not limited to the honeycomb shape, and may be, for example, a particulate shape as long as there is no problem of dust clogging or pressure loss.

The function of the ozone deodorizing device 13 is as follows.
In FIG. 1, an inkjet head 11 ejects ultraviolet curable ink I onto a recording medium S, and an ultraviolet light source 12 for curing the ink irradiates the ejected ink with ultraviolet rays to be cured. At this time, ozone is generated by the ultraviolet light source 12 for ink curing. The stronger the brightness, the more ozone is generated. This ozone is collected in the ozone deodorizer 13 by a cooling fan of the ultraviolet light source 12.

FIG. 2 shows two specific methods for collecting ozone generated by the ultraviolet light source 12 in the ozone deodorizing device 13 with a cooling fan. (A) is a lamp horizontal type, and (b) is a lamp vertical type.
In each figure, the light from the lamp 12a irradiates the ink I on the recording medium S below, and a large amount of ozone O3 is generated around the lamp 12a.
Conventionally, ozone O3 was left unattended, but ozone O3 was discharged from the opposite side of the lamp housing 12b (FIG. A) by the air flow of the cooling fan 12c that cools the lamp 12a, and the ozone deodorizing device arranged in the vicinity. Keep in 13.

  On the other hand, in FIG. B, a large amount of ozone O3 generated in the vicinity of the lamp 12a is sucked up and stored in the ozone deodorizing device 13 arranged in close proximity by the principle of the Pitot tube (a flow is generated from the high pressure side to the low pressure side). Keep it.

  Now, returning to FIG. 1, a large amount of ozone O3 collected as shown in FIG. 2 is present in the ozone deodorizing apparatus 13 of FIG. An opening is opened in the housing 19 region on the opposite side of the ink landing region with the ozone deodorizing device 13 as the center, and the activated carbon filter 14 is fitted therein. An exhaust fan 15 for discharging the internal air to the outside of the housing 19 is provided to face the activated carbon filter 14. Therefore, when the exhaust fan 15 is rotated, the odor generated from the ejected ink I advances in the arrow N direction and enters the ozone deodorizing device 13. Since the ozone deodorizing device 13 itself is a porous material, it can enter from any direction.

  Therefore, the odor that has entered the ozone deodorizing device 13 comes into contact with the ozone deodorizing device 13, and the odor is decomposed by oxidative decomposition treatment (deodorizing treatment) with a large amount of ozone O3. According to the present invention, it is possible to obtain both effects.

  Further, even when ozone having a reaction equivalent or more with respect to the total amount of odor components in the odor gas is injected into the deodorization device, the remaining unreacted ozone is decomposed in the ozone deodorization device 13, so the deodorization device 13. Ozone odor is hardly generated at the outlet of the gas, but when some ozone is discharged, the activated carbon filter 14 decomposes ozone. In this way, in any case, neither ozone nor odor is discharged outside the apparatus.

  When the temperature of the odor gas is lowered, the adsorption capacity of the catalyst in the ozone deodorizer 13 for the odor component tends to be remarkably lowered. According to the present invention, the hot air that has cooled the ultraviolet light source 12 is applied to the odor gas. Therefore, since the odor gas is warmed, moisture condensation on the catalyst can be prevented, and the adsorption capacity (deodorization performance) can be stably maintained for a long period of time, that is, there is a separate heating device for warming the odor gas. A third secondary effect that it becomes unnecessary is obtained.

Next, measurement and control of the ozone amount in the ozone deodorizing apparatus 13 will be described.
For the measurement of the amount of ozone, for example, a commercially available ozone sensor using the principle of an ultraviolet absorption type can be used. If this ozone sensor is installed in the ozone deodorizing device 13, the analog output value of the ozone sensor changes depending on the ozone concentration, so if the analog output value of the ozone sensor decreases, the ozone concentration decreases. Therefore, a large amount of ozone is generated, and in the opposite case, it is suppressed.
The ozone amount is controlled by the brightness of the ultraviolet irradiation lamp. Increasing the luminance increases the amount of ozone, and decreasing the luminance decreases the amount of ozone.

  Alternatively, the amount of ozone generated can be changed by controlling the temperature of the surface of the ultraviolet irradiation lamp 12 by changing the rotational speed of the cooling fan that cools the ultraviolet irradiation lamp 12 while keeping the luminance constant. When the amount of ozone is small, the number of revolutions may be decreased, and if it is excessive, the number of revolutions may be increased.

  The timing of controlling the amount of ozone should be avoided because the ink is irradiated with energy that exceeds the desired amount of energy during ink irradiation. It is good to carry out in the period when ink irradiation is not performed (for example, the return period of an inkjet head). Further, even if the amount of ozone in the ozone deodorizing device 13 increases, the lamp does not turn off (because it takes time to rise to a predetermined brightness once the lamp is turned off), the lamp brightness is maintained in a lowered state. It is good.

  As described above, according to the present invention, all odor components contained in ozone and odor gas are oxidatively decomposed (deodorized) by ozone in the ozone deodorizing device 13 and are exhausted by the exhaust fan 15 as odorless gas. Released into the outside atmosphere.

FIG. 3 shows a schematic configuration diagram of a photocurable ink jet recording apparatus according to Embodiment 1 in which the apparatus of the present invention of FIG. 1 is mounted.
In the figure, in a housing 10, a recording medium storage unit 20 that stores a plurality of sheet-shaped recording media S of the same size and a transport unit 30 that takes out the recording medium S from the storage unit 20, A scanning conveyance unit 40 that conveys the recording medium S carried by the conveyance unit 30 while holding it in the recording position range, and an inkjet image recording scan and ultraviolet light irradiation fixing to the recording medium S that is held and transferred by the scanning conveyance unit 40. (In this embodiment, ultraviolet light is used) and a tray 90 to which the recording medium S that has been recorded by the image recording unit 50 is sent out.

  In the recording medium storage unit 20, a storage cassette 22 for storing the recording medium S is detachably disposed at the bottom of the housing 12 of the photocurable inkjet recording apparatus 10, 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 includes a feed roller 32 that abuts on the leading end of the recording medium S in the storage cassette 22 set in the housing 12 in the insertion direction, and further transports and scans the recording medium S fed out by the feed roller 32. Conveying roller pairs 34 and 36 for conveying to the section 40 are provided.

  The transport scanning unit 40 includes a transport 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, the head unit 52 is provided with the tip of the ink ejection unit directed toward the transport belt 42 at the image recording position 42P. A head driver 54 is connected to the head unit 52 to control the ejection amount of each ink color. The head unit 52 is connected to an ink supply unit 70 for supplying ink.
In addition, an ultraviolet irradiation unit 56 is disposed downstream of the head unit 52 and applies light energy to the ink to cure it. An ozone deodorizing device 59 is disposed immediately downstream of the ultraviolet irradiation unit 56 according to the present invention.
In the ultraviolet irradiation unit 56, as described above, strong light is used to cure the ink, so that the temperature in the housing 12 rises. In order to suppress this, the exhaust cooling unit 80 is disposed in the upper part of the housing 12.
The ozone generated from the ultraviolet irradiation unit 56 is collected and the odor generated from the ink discharged to the recording medium S is also collected and oxidized and decomposed (deodorized), and activated carbon by an exhaust fan of the exhaust cooling unit 80 as odorless gas. It is discharged into the atmosphere outside the machine through the filter 215.

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 conveys the recording medium S near the downstream belt roller 44c. The peeling from the belt 42 is promoted. The tray 90 accommodates the recording medium S peeled from the conveyance belt 42.
As another configuration of the recording medium storage unit 20 described above, a cassette for supplying a recording material wound on a roll may be used. In this case, a cutter that cuts the recording material into a desired length is disposed in place of the operation roller 32 of the transport unit 30.

  Next, the present invention will be described along a series of operations of the present embodiment.

  The recording medium S held on the conveyance belt 42 is used for conveyance by the conveyance belt 42 when the leading end reaches the image recording position 42P. The head unit 52 of the image recording unit 50 has an ink discharge port in the width direction of the conveyance belt 42, and performs image recording scanning in accordance with the scanning timing of the conveyance belt 42. At this time, the image data is input to the head driver 54, the ink is guided from the ink supply unit 70, and the ink discharge amount from the head unit 52 is controlled. The distance between the tip of the head unit 52 and the recording medium S is always constant due to the uniform force due to electrostatic adsorption, and high-quality image formation is performed. Furthermore, it has been found that high image quality can be achieved by improving the landing position accuracy considered to be due to the electric field formed by the charging potential of the recording medium and improving the ink wettability.

As described above, the ultraviolet irradiation unit 56 and the ozone deodorizing device 59 are disposed downstream of the head unit 52. As a result, the ink is cured by being irradiated with ultraviolet rays by the ultraviolet irradiation unit 56, and the odor from the ink is oxidatively decomposed (deodorized) by the ozone deodorizer 59.
Further, the ultraviolet irradiation unit 56 is configured so that the ink discharge port of the head unit 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.
In this embodiment, a metal halide lamp is used as the light source of the ultraviolet irradiation unit 56. However, any other light source that generates light (specifically, ultraviolet light, electron beam, etc.) may be used. LED, ultraviolet laser, etc. can be raised.

  In the vicinity of the downstream belt roller 44c disposed downstream of the ultraviolet irradiation unit 56, as described above, the recording medium S is peeled from the transport belt 42 by the peeling claw 92 at a position where the recording medium S is separated from the transport belt 42. The recording medium S is sent onto the tray 90.

  A cleaning roller 45 rotates in contact with the conveyor belt 42 past the position of the downstream belt roller 44c. The surface of the cleaning roller 45 is sticky and removes dust, ink residue, and the like from the conveying belt 42 to prepare for the next image recording. Cleaning means other than the cleaning roller 45 have been proposed. Wiping with a non-woven fabric is also possible.

FIG. 4 is a schematic configuration diagram of a photocurable inkjet recording apparatus according to Embodiment 2 of the present invention.
In the figure, the movable platen 240 supports the recording medium S during recording conveyance. The movable platen 240 has a flat plate shape, and is preferably set to a size slightly larger than the maximum size of the recording medium S to support the entire recording medium. A ball nut 244 is fixed to the back surface of the movable platen 240 with respect to the recording material support surface by a bracket 245. A ball screw shaft 246 that passes through the ball nut 244 is arranged with its longitudinal direction parallel to the conveyance direction of the recording medium S. The ball nut 244 meshes with the ball screw shaft 246 and is driven by the rotation R of the ball screw shaft 246 to be restricted to the forward / backward movement X in the recording medium conveyance direction.

  A driven timing pulley 264 is disposed at the downstream end of the ball screw shaft 246 in the conveying direction. A drive motor 260 is disposed below the movable platen 240. A timing belt 266 is stretched between the drive timing pulley 262 and the driven timing pulley 264 that are rotationally driven by the drive motor 260 to transmit the rotational drive. The rotation by the drive motor 260 rotates the driven timing pulley 264 and rotates the ball screw shaft 246. This rotation is finally converted to linear movement in the recording medium conveyance direction by the ball nut 244. The movable platen 240 reciprocates between an initial position indicated by a solid line and a most downstream position indicated by a one-dot chain line in the drawing.

  Further, a plurality of air intake holes (not shown) are arranged on the recording medium placement surface of the movable platen 240. These intake holes are connected to piping inside the platen and further connected to an intake pipe 249 provided at the lower part of the movable platen 240. The intake pipe 249 is connected to an intake portion 247 disposed below the movable platen 240, and the recording medium S placed on the movable platen 240 is adsorbed by driving the intake portion 247.

  An image recording unit 150 is disposed near and above the intermediate position between the initial position and the downstream position of the movable platen 240. The image recording unit 150 includes a multi-channel type head unit 152, and the head unit 152 is suspended and supported by a guide member 158 extending in the scanning direction orthogonal to the back-and-forth movement X in the recording medium conveyance direction. The head unit 152 performs reciprocating scanning along the guide member 158. Basically, each photocurable ink of five colors (white W, yellow Y, magenta M, cyan C, black K) is applied to the recording medium S. Five nozzle groups each ejecting toward the recording surface are provided (in the vertical direction on the paper surface).

  In the case of the second embodiment in which the head unit 152 performs reciprocating scanning along the guide member 158, the ultraviolet irradiation units 156 are disposed on both sides of the head unit 152 with the head unit 152 interposed therebetween. The ozone deodorizing device 159 is disposed in the vicinity of at least one of the ultraviolet irradiation units 156 on both sides, and the ultraviolet irradiation unit 156 and the ozone deodorizing device 159 are moved together with the reciprocating movement of the head unit 152 and discharged from each nozzle. The ultraviolet curable ink that lands on the recording medium S is irradiated with ultraviolet rays, and ozone from the ultraviolet irradiation unit 156 and odors from the ejected ink are deodorized by the ozone deodorizing device 159. In this second embodiment, the ozone deodorizing device 159 moves, so the exhaust fan (FIG. 1) and the ozone deodorizing device 159 are preferably connected with a hose made of a stretchable material.

Next, the operation of the second embodiment will be described.
First, in the case of the present embodiment, the recording medium S is supplied to the recording apparatus by hand by hand as needed. The recording medium S supplied by a human hand is placed on the movable platen 240 in the initial position. The movable platen 240 remains stopped until the entire recording medium S is completely placed thereon.

  The cartridge mounting unit 70 is connected to the head unit 152, and the cartridge mounting unit 70 stores five inks storing W (white) Y (yellow) M (magenta) C (cyan) K (black). The cartridge 72 is mounted. Moreover, it can comprise so that attachment or detachment is possible respectively. As the ink supply path, first, the ink supply path 78 is connected from each cartridge 72 so as to be led out. Further, each ink supply path 78 is connected to the head-side ink supply path 155 via the valve unit 76 and is connected to each ink head of the head unit 152. On the other hand, the ink path from the valve unit 76 to the pump unit 74 branches, and the valve unit 76 and the pump unit 74 form an ink circulation part 75. An ink reflux path 79 is connected to each cartridge 72 from the pump unit 74 of the ink circulation unit 75.

Next, the operation of the second embodiment will be described.
First, in the case of the present embodiment, the recording medium S is supplied to the recording apparatus by hand by hand as needed. The recording medium S supplied by a human hand is placed on the movable platen 240 in the initial position. The movable platen 240 remains stopped until the entire recording medium S is completely placed thereon.

  At the time of image recording in which the head unit 152 is operated, the valve unit 76 makes the ink supply path 78 and the head side ink supply path 155 conductive. Therefore, ink is supplied from the cartridge mounting unit 70 in accordance with the driving of the head unit 152.

  Here, the path of the valve unit 76 is switched and the cartridge is mounted after a time has passed so long as the precipitation in the ink in the ink path becomes apparent when the photo-curable inkjet recording apparatus is turned on or when image recording is stopped. The unit 70 side ink supply path 78 is connected to the ink reflux path 79 via the pump unit 74. Then, by driving the pump unit 74, the ink in the ink supply path 78 starts to reflux.

Image recording is started by an image recording start button (not shown) provided in the image recording apparatus. At this timing at the latest, the intake section is driven, and the recording medium S placed on the movable platen 240 is adsorbed. At this timing, driving for moving the movable platen 240 by the driving motor 260 is started.
Here, the rotational force of the drive motor 260 is transmitted to the drive timing pulley 262, the timing belt 266, and the driven timing pulley 264 to rotate the ball screw shaft 246. This rotation is converted to a linear movement in the downstream direction by the ball nut 244.

Then, the movable platen 240 is moved from the initial position to the most downstream position (indicated by a one-dot chain line). At this time, image recording by the image recording unit 150 is started. That is, the ball nut 244 is moved at an image recording speed, and the image recording scan is executed by the head unit 152 on the recording medium S on the movable platen 240 that moves together. At this time, the ozone deodorizing device 159 provided by the present invention takes in the odor of the ink discharged to the recording medium S and the ozone from the ultraviolet irradiation unit 156, and deodorizes the odor and the odor of ozone. Thus, after the image recording is completed, the recorded recording medium S is manually collected from the platen 240 at the most downstream position (indicated by a one-dot chain line). There is no odor coming out of the device.
After the recording medium S is removed, the movable platen 240 at the most downstream position (one-dot chain line) returns to the initial position by the reverse drive of the drive motor 250 to prepare for the next image recording.

  Here, the “light” 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, but the curing sensitivity and the device are not limited. From the viewpoint of availability, ultraviolet rays are 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 inkjet recording apparatus of the present invention, the peak wavelength of light depends on the absorption characteristics of the sensitizing dye in the ink composition, but is, for example, 200 to 600 nm, preferably 300 to 450 nm, and more preferably 350 to 450 nm. It is appropriate that The (a) electron transfer start system of the ink composition of the present invention has sufficient sensitivity even with low output light. Therefore, the light output 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 / cm ² . A radiation energy of cm ² is appropriate. Further, the light exposure surface illuminance (the maximum illuminance of the surface of the recording medium) is, for example, 10 to 2,000 mW / cm ^2, is preferably a suitably be irradiated at 20 to 1,000 mW / cm ² .
In particular, in the ink jet recording apparatus of the present invention, light irradiation generates ultraviolet rays having an emission wavelength peak of 390 to 420 nm and a maximum illuminance on the recording medium surface of 10 to 1,000 mW / cm ^2. Irradiation from a light emitting diode is preferred.

In the ink jet recording apparatus of the present invention, it is appropriate that light 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. is there.
Furthermore, in the 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 on the recording medium to the light irradiation is 0.01 to 0.5 seconds. Desirably, it is preferably 0.01 to 0.3 seconds, more preferably 0.01 to 0.15 seconds. Thus, by controlling the time from the landing of the ink composition to the recording medium to the irradiation of light to an extremely short time, it is possible to prevent the landed ink composition from bleeding before being cured.

  In order to obtain a color image using the ink jet recording apparatus of the present invention, it is preferable to superimpose in order from the color with the lowest brightness. By overlapping in this way, light 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 it is possible to irradiate light and expose all colors at once, it is preferable to expose each color in terms of promoting curing.

  The inkjet head of the present invention is, for example, a piezo-type inkjet head, and multi-size dots 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. It can drive so that it can inject with the resolution of. In the present invention, dpi represents the number of dots per 2.54 cm.

  Further, as described above, it is desirable that the photocurable ink such as the ink composition of the present invention has a constant temperature for the ink composition to be ejected. It is preferable to perform temperature control by 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, gas / solid lasers, and the like are mainly used as light 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, LEDs (UV-LED) and LD (UV-LD) are small, have a long life, have high efficiency, and are low in cost, and are expected as radiation sources for photo-curable ink jets.

  As described above, a light emitting diode (LED) and a laser diode (LD) can be used as the light 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 light centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. A particularly preferable light source in the present invention is a UV-LED, and a UV-LED having a peak wavelength at 350 to 420 nm is particularly preferable.

〔recoding media〕
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and various non-absorbing resin materials used for ordinary non-coated paper and coated paper, so-called soft packaging, or films thereof. A resin film molded into a shape can be used, and examples of 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 a 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 are susceptible to curling and deformation, such as heat-shrinkable PET film, OPS film, OPP film, ONy film, PVC film, etc., have the advantage that high-definition images 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 light, 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 ink composition contains (a) a cationic polymerizable compound and (b) a compound that generates an acid upon irradiation with light. If desired, it may further contain (d) an organic acidic component having a pKa value of 2 to 6, (e) a colorant, 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 upon irradiation with light (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 aromatic 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-epoxy Hexylmethyl) 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) ), Dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 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 -Diepoxyoctane, 1,2,5,6-diepoxycyclooctane and the like.

  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, di- or trivinyl ether compounds are preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and divinyl ether compounds are 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 in a good handling range, and it is possible to obtain high adhesion between the cured ink composition and the recording medium. it can.

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 light]
The ink composition of the present invention contains a compound that generates an acid upon irradiation with light (hereinafter, appropriately referred to as “photoacid generator”).
As the photoacid generator that can be used in the present invention, it is used as a photoinitiator for photocationic polymerization, a photoinitiator for radical photopolymerization, a photodecolorant for dyes, a photochromic agent, or an ozone deodorizer resist. Irradiation with light (400-200 nm ultraviolet light, far ultraviolet light, particularly preferably g-line, h-line, i-line, KrF excimer laser beam), ArF excimer laser beam, electron beam, X-ray, molecular beam or ion beam The compound which generates an acid can be appropriately selected and used.

  Examples of such a photoacid generator include an onium salt such as diazonium salt, ammonium salt, phosphonium salt, iodonium salt, sulfonium salt, selenonium salt, and arsonium salt, which generates an acid upon decomposition by light irradiation, organic Halogen compounds, organometallic / organic halides, photoacid generators having o-nitrobenzyl type protecting groups, compounds that generate sulfonic acids upon 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.

[(D) Organic acidic component having a pKa value of 2 to 6]
In the ink composition of the present invention, (d) an organic acidic component having a pKa value of 2 to 6 (hereinafter sometimes simply referred to as “organic acidic component”) can be added. The organic acidic component (d) having a pKa value of 2 to 6 used in the present invention corresponds to a qualitatively weakly acidic organic compound. When the pKa of the organic acidic component is larger than 6, the sensitivity is lowered when it is added to the ink composition of the present invention. In the present invention, it is preferable to apply an organic acidic component having a pKa value of 2 to 6.

  Specific examples of the organic acidic component having a pKa value of 2 to 6 include carboxylic acids. Examples of carboxylic acids include acetic acid, phenylacetic acid, phenoxyacetic acid, methoxypropionic acid, lactic acid, hexanoic acid, heptanoic acid, octanoic acid, palmitic acid, stearic acid, oleic acid, linolenic acid, cyclopropylcarboxylic acid, cyclobutanecarboxylic acid. Acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, 1-adamantanecarboxylic acid, 1,3-adamantanedicarboxylic acid, norbornene-2,3-dicarboxylic acid, abietic acid, trans-retinoic acid, cyclohexylacetic acid, dicyclohexylacetic acid, Adamantane acetic acid, malonic acid, malonic acid monomethyl ester, fumaric acid, maleic acid, maleic acid monomethyl ester, itaconic acid, crotonic acid, succinic acid, adipic acid, sebacic acid, glycolic acid, diglycolic acid, mandelin , Tartaric acid, malic acid, arginic acid, cinnamic acid, methoxycinnamic acid, 3,5-dimethoxycinnamic acid, benzoic acid, salicylic acid, 4-hydroxybenzoic acid, gallic acid, 3-nitrobenzoic acid, 3-chloro Benzoic acid, 4-vinylbenzoic acid, t-butylbenzoic acid, 1-naphthoic acid, 1-hydroxy-2-naphthoic acid, fluorenone-2-carboxylic acid, 9-anthracenecarboxylic acid, 2-anthraquinonecarboxylic acid, phthalic acid , Phthalic acid monomethyl ester, isophthalic acid, terephthalic acid, trimellitic acid, trimellitic acid monomethyl ester, and other aliphatic or aromatic monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids having 1 to 20 carbon atoms. However, it is not limited to this.

[(E) 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. Although the ink composition of the present invention is a photocurable ink, it is preferable that the ink composition is solvent-free because it is cured after being applied to a recording medium. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a VOC (Volatile Organic Compound) problem 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]
A sensitizer may be added to the ink composition of the present invention as necessary 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, polymerization is not hindered to improve adhesion to recording media such as leveling additives, matting agents, waxes for adjusting film physical properties, polyolefins, PET, etc., if necessary. A tackifier or the like 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. 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 30 mN / m, more preferably 23 to 28 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 the wettability is preferably 30 mN / m or less.

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 light and cured to perform recording.
In the printed matter obtained with this ink, the image portion is cured by irradiation with light 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) of a lithographic printing plate Part), and can be used for various purposes.

[Radical polymerization ink composition]
The radical polymerization ink composition contains a radical polymerizable compound and a polymerization initiator. If desired, it may further contain a sensitizing dye, a coloring material, and the like.
Hereinafter, each component used for the radical polymerization ink composition will be sequentially described.

[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 And sorbitol tetritaconate.

  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) (where 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%, based on all components of the ink composition. Mass%).

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

  Preferred photopolymerization initiators include (a) aromatic ketones, (b) aromatic onium salt compounds, (c) organic peroxides, (d) hexaarylbiimidazole compounds, (e) ketoxime ester compounds, f) borate compounds, (g) azinium compounds, (h) metallocene compounds, (i) active ester compounds, (j) compounds having a carbon halogen bond, and the like.

[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 include 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 an 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 light. 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 light]
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 The use etc. for the overcoat for the purpose of provision etc. are mentioned. 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 active 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 above-described water-soluble polymerizable compound is used in an ink containing a coloring material, the concentration of the polymerization initiator and the polymerizable substance in the ink can be adjusted according to the absorption characteristics of the contained coloring material. preferable. 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.

It is a principle diagram of ozone deodorization according to the present invention in a photocurable ink jet recording apparatus. Two specific methods for collecting ozone generated by the ultraviolet light source in the ozone deodorizer 13 with a cooling fan are shown. (A) is a lamp horizontal type, and (b) is a run-op vertical type. BRIEF DESCRIPTION OF THE DRAWINGS It is the structure schematic of the photocurable inkjet recording device of Embodiment 1 carrying the ozone deodorizing apparatus of this invention. It is the structure schematic of the photocurable inkjet recording device of Embodiment 2 carrying the ozone deodorizing apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photocurable inkjet recording device 12 Case 13, 59, 159 Ozone deodorizing device 14, 215 Activated carbon filter S Recording medium 20 Recording medium storage part 22 Storage cassette 30 Conveyance part 32 Feed roller 34, 36 Conveyance roller pair 40 Conveyance scanning part 44a, 44b, 44c Belt roller 42 Conveying belt 42P Image recording position 50 Image recording unit 52 Head unit 54 Head driver 70 Ink supply unit 56, 159 Ultraviolet irradiation unit 80 Exhaust cooling unit 90 Tray 92 Separation claw 136 Scanning conveyance roller pair 140 Platen 150 Image recording unit 152 Head unit 156a, 156b UV irradiation unit 158 Guide member 240 Moving platen 244 Ball nut 245 Bracket 246 Ball screw shaft 250 Image recording unit 260 Drive motor 262 Drive timing Li 264 driven timing pulley 266 timing belt R rotational direction X moving direction

Claims (4)

  Ultraviolet energy irradiation means, an inkjet head that discharges ink curable by ultraviolet energy irradiated by the ultraviolet energy irradiation means toward a recording medium based on an image signal, and the recording medium at a position facing the inkjet head In a photo-curable inkjet recording apparatus having a recording medium conveying means for conveying, an ozone deodorizing means for collecting ozone generated by the ultraviolet irradiation means is provided, and an odor generated from the ink is introduced into the ozone deodorizing means. The photo-curable ink jet recording apparatus, wherein the ozone deodorizing means deodorizes the ink odor.   2. The photocurable ink jet recording apparatus according to claim 1, further comprising a cooling fan for flowing air so that the cooling air that has passed over the ejected ink passes through the ozone deodorizing means.   3. The photocurable ink jet recording apparatus according to claim 2, wherein the air passing through the ozone deodorizing means is exhausted outside the apparatus.   4. An ink jet apparatus according to claim 3, wherein an activated carbon filter is provided at an outside outlet for exhausting air that has passed through the ozone deodorizing means to the outside.

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