JP2006347024A - Optical energy-curable inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical energy-curable inkjet recording device which can draw a high quality image with excellent color reproducibility, when color-matching an image drawn on a printing surface. <P>SOLUTION: This optical energy-curable inkjet recording device comprises an inkjet head which discharges an ink to be cured by irradiating with an optical energy, to a light-transmitting recording medium, a conveyance means for conveying the light-transmitting recording medium, an energy irradiation means which irradiates the printing surface where the ink of the light-transmitting recording medium is discharged, and a color detection means which detects the color of an image drawn to the printing surface from a non-printing surface on the opposite side to the printing surface of the light-transmitting recording medium. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light energy curable ink jet recording apparatus having a color correcting means for a translucent recording medium.

  Currently, an ink that is cured by light energy such as ultraviolet rays is ejected onto a recording medium by an inkjet head, and the ejected ink is irradiated with energy and cured to form an image on the recording medium. There is an apparatus (for example, Patent Document 1 below). Such a light energy curable ink jet recording apparatus is environmentally friendly and can perform high-speed recording on many types of recording media. In addition, a good high-definition image is obtained in which ink does not easily spread on the recording medium. Etc.

  The light energy curable ink jet recording apparatus is particularly suitable for use in recording on a translucent recording medium such as a transparent plastic film because the ink hardly bleeds when an image is formed on a non-absorbing recording medium. Is suitable.

JP 2004-181643 A

By the way, when an image is formed on a translucent recording medium, an image formed from a non-printing surface opposite to the printing surface on which ink is drawn is often visually recognized. At this time, the user performs color matching based on the color of the image viewed from the non-printing surface. However, when observing the color of an image formed on the printing surface from the non-printing surface of the translucent recording medium, it is difficult to accurately perform color matching. In particular, when irradiating light from the printing surface and observing the color of the image from the non-printing surface, accurate color matching is difficult, and printing and printing many sheets of recording media is wasteful. There was room for improvement.
Furthermore, normally, when the translucent recording medium is transported by the transport belt, the non-printing surface is in contact with the surface of the transport belt, so it is very difficult to check the print surface from the non-printing surface. It was difficult.

  The present invention has been made in view of the above circumstances, and its purpose is excellent in color reproducibility when performing color matching of an image drawn on a printing surface from a non-printing surface side of a translucent recording medium, An object of the present invention is to provide a light energy curable ink jet recording apparatus capable of drawing with high image quality.

  An object of the present invention is to provide an inkjet head that ejects ink that is cured by light energy irradiation onto a translucent recording medium, a transport belt that transports the translucent recording medium, and the translucent recording. An energy irradiating unit that irradiates light energy onto a printing surface of the medium on which the ink is ejected, and a color detecting unit that detects the color of the ink, and the detection light can be transmitted through at least a part of the conveyor belt. A light energy curable type, characterized in that a light transmitting portion is provided, ink is landed on the light transmitting portion at the time of color detection, and the landed ink is detected by the color detecting means through the light transmitting portion. This is achieved by an ink jet recording apparatus.

  The light energy curable ink jet recording apparatus of the present invention is provided with a color detecting means for detecting the color of ink landed on a light transmitting portion provided on a transport belt. And before actually printing on a recording medium, the color of the ink directly landed on the translucent part is detected by this color detection means. In this way, when color matching of images is performed, the color tone of the ink is detected by the color detection means via the translucent part, so that the desired color tone is obtained based on the color of the ink in the translucent part. The head unit can be adjusted so that At this time, since the ink is not landed on the recording medium at the time of color detection, loss of the recording medium consumed for color detection can be omitted. In addition, if the configuration is such that the color is detected by the color detection means, it is possible to perform highly reliable color matching compared to what the user observes the color by visually recognizing the user, Stable color reproducibility can be ensured and high-quality drawing can be performed. Further, unlike the prior art, it is not necessary to perform color matching repeatedly, and it is possible to avoid the occurrence of loss such as printing out a number of recording media.

  When detecting the color of the ink landed on the translucent part, a control unit for controlling the transport belt is provided so that the translucent part moves to a position where the detection light can be detected by the color detecting means. It is preferable that In this way, when performing color detection, the conveyance belt is driven and controlled, so that the position where the translucent part cannot transmit the detection light by driving the conveyance belt or the transmitted detection light is transmitted by the color detection means. It is possible to avoid moving to a position that cannot be detected, and to move the translucent part to an appropriate position. For this reason, since it is not necessary to set it as the structure which provides a translucent part in most conveyance belt surfaces, the mechanical strength of a conveyance belt is fully securable.

  In the light energy curable ink jet recording apparatus, it is preferable that a cleaning unit is provided which is formed so as to be in contact with the light transmitting portion of the transport belt and cleans the surface of the light transmitting portion. In this way, it is possible to prevent the ink that has landed on the translucent part from being removed by contacting the cleaning means and adhering to the transported recording medium, and to detect the next color. Can be done accurately.

  In the light energy curable ink jet recording apparatus, it is preferable that a control unit for adjusting a driving condition of the ink jet head is provided based on a color detection value obtained by the color detection means. In this way, if the color detection value is output to the control unit as an accurate information signal by the color detection means, the drive condition of the inkjet head can be accurately controlled based on the information signal by the control unit. become.

  In addition, the image forming apparatus includes a calculation unit to which a lookup table indicating the relationship of the inkjet head drive voltage to the color density is input, and the calculation unit compares the lookup table with the color of the image to determine the inkjet head drive conditions. Is preferably adjusted. In this way, by preparing a look-up table in advance, when actually performing color matching, the actual color value of the image detected by the color detection means is compared with the look-up table. By doing so, it is possible to determine the driving voltage of the inkjet head to be set in order to obtain a desired color, and it is possible to perform color matching more accurately by controlling the inkjet head by the control unit according to this driving voltage. Color reproducibility can be improved.

  According to the present invention, when performing color matching of an image drawn on the printing surface from the non-printing surface side of the translucent recording medium, light energy curing that can perform high-quality drawing with excellent color reproducibility. Type inkjet recording apparatus can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a light energy curable ink jet recording apparatus according to an embodiment of the present invention.
In FIG. 1, the light energy curable ink jet recording apparatus 10 has a housing 12. Inside the housing 12, a sheet-shaped translucent recording medium (hereinafter also simply referred to as “recording medium”) S of the same size is stored, and a recording medium storage unit 20 that stores a plurality of sheets is taken out from the storage unit 20. Transport unit 30 that functions as a transport unit that transports the recorded recording medium S, and scanning transport that scans the recording medium S while restricting the recording medium S transported from the transport unit 30 to be held in the recording position range. An image is formed by ejecting ink, which will be described later, onto the recording medium S that is held, transported, and scanned by the scanning unit 40 and the scanning conveyance unit 40, and the ink that forms the image is irradiated with light energy such as ultraviolet light. An image recording unit 50 that performs a process of fixing ink to the recording medium S and a tray 90 to which the recording medium S on which an image is drawn by the image recording unit 50 are sent out are provided.

  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 casing 12 of the light energy curable inkjet recording apparatus 10. The recording medium storage unit 20 can be supplied with recording media S of different sizes by replacement. Further, the recording medium storage unit 20 can be configured to mount a plurality of cassettes.

  In the transport unit 30, the top end in the insertion direction of the uppermost recording medium S stored in the storage cassette 22 in the state where the storage cassette 22 is loaded in the housing 12 at the most upstream part in the transport direction of the recording medium S. A feed roller 32 abutting on the part is provided. Further, conveyance roller pairs 34 and 36 for conveying the recording medium S fed by the feed roller 32 to the scanning unit 40 are provided.

  The scanning conveyance unit 40 includes a conveyance belt 42 that is stretched and driven by three conductive 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.

  In the scanning conveyance unit 40, the position where the leading edge of the recording medium S conveyed from the conveyance roller pair 36 of the conveyance unit 30 first contacts the conveyance belt 42 (the position of the upstream belt roller 44b in this embodiment shown in FIG. 1). Is provided with a corona charger 46. The corona charger 46 has a function of bringing the conveyance belt 42 and the recording medium S into close contact with each other by corona charging, and is disposed so as not to contact the recording medium S on the conveyance belt 42 and close to the conveyance belt 42. .

  In the scanning conveyance unit 40, a static eliminator 48 is provided at a position where the recording medium S is separated from the conveyance belt 42 (in this embodiment, the downstream belt roller 44c position). The static eliminator 48 is disposed so as not to contact the recording medium S on the conveyance belt 42 and in the vicinity of the conveyance belt 42. In the scanning conveyance unit 40, an almost intermediate position between the upstream belt roller 44b and the downstream belt roller 44c is set as an image recording position 42P. The corona charger 46 and the static eliminator 48 may be omitted and the configuration omitted.

  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, and the ejection amount of each ink color of the head unit 52 is controlled by driving the head drive 54. The head unit 52 is connected to an ink supply unit 70 for supplying ink.

  Further, an ultraviolet irradiation unit 56 is arranged immediately after the image recording position 42P and downstream of the head unit 52. In addition, the ultraviolet irradiation part 56 is good also as a structure assembled | attached to the head unit 52 so that it may mention later. The ultraviolet irradiation unit 56 functions as energy irradiation means for irradiating the ink ejected onto the recording medium S with ultraviolet light, which is light energy. Hereinafter, it is also referred to as energy irradiation means 56.

  Since the ultraviolet irradiation unit 56 uses high light energy to cure the ink ejected to the recording medium S as described above, the temperature inside the housing 12 is increased by the heat generated in the vicinity of the ultraviolet irradiation unit 56. To rise. Therefore, an exhaust cooling unit 80 is disposed in the upper part of the housing 12 in order to suppress an increase in the temperature inside the housing 12. Hot air inside the housing 12 is discharged to the outside of the housing 12 via the exhaust cooling unit 80.

  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 has a function of sequentially stacking and storing the recording media S peeled from the transport belt 42. A tray 90 is provided at a position downstream of the peeling claw 92 in the transport direction. The tray 90 has a leading end side (that is, a downstream side in the transport direction) located outside the housing 12, a trailing end portion located inside the housing 12, and a leading end portion lower than the rear end portion. Thus, they are arranged at a predetermined inclination angle.

Next, the transport system of the light energy curable ink jet recording apparatus according to the present invention will be described.
FIG. 2 is a diagram for explaining a transport system of the light energy curable inkjet recording apparatus of the present embodiment.

  As shown in FIGS. 1 and 2, the transport mechanism of the present embodiment includes a transport belt 42, and the transport belt 42 is stretched and driven by three belt rollers 44a (not shown), 44b, and 44c. The conveying belt 42 is driven from the upstream belt roller 44b toward the downstream belt roller 44c, and the recording medium S is placed on the conveying belt 42 between the upstream belt roller 44b and the downstream belt roller 44c and along the conveying direction A. Be transported.

  A head unit 52 is disposed above the recording medium S. The head unit 52 is suspended and supported by a guide member 58 extending in a direction (scanning direction B) orthogonal to the transport direction A, and is reciprocally movable along the scanning direction B while being guided by the guide member 58. Yes.

  Here, the head unit 52 includes four recording heads that respectively eject ultraviolet curable inks of four colors (yellow Y, magenta M, cyan C, and black K) toward the recording surface of the recording medium S.

  In the figure of the head unit 52, two ultraviolet irradiation units 56a and 56b that perform ultraviolet irradiation are mounted on both the left and right sides, respectively, and the ultraviolet irradiation units 56a and 56b can be moved together by the reciprocating movement of the head unit 52. Yes. The ultraviolet curable ink ejected from each nozzle and landed on the recording medium S is irradiated with ultraviolet rays by at least one ultraviolet irradiation unit of the ultraviolet irradiation units 56a and 56b passing immediately above.

  In FIG. 2, a so-called scanning head unit that scans the recording medium S is provided. However, the recording heads are arranged in parallel in the width direction of the recording medium S (left and right directions in FIGS. 2 and 3). A so-called full line head type head unit may be provided. In this case, an ultraviolet irradiation unit capable of irradiating at least the full width of the recording medium is arranged downstream of the sub-line full line head. Further, a plurality of ultraviolet irradiation units capable of irradiating light at least the full width of the recording medium may be arranged downstream of each of the minor number of full line heads.

  FIG. 3 is a schematic diagram for explaining a state in which an image is formed on a recording medium in the present embodiment.

  In the present embodiment, at least a part of the transport belt 42 is provided with a translucent portion 42A made of a light-transmitting material so that the color can be detected by the color detection means 14. Further, the color detecting means 14 is provided so as to face the surface opposite to the transport surface (upper side surface in FIG. 3) for transporting the recording medium S. The color detection unit 14 has a function of detecting the color of the ink droplet d1 discharged to the light transmitting portion 42A of the transport belt 42 from the non-printing surface side. As the color detection means 14, a known color detection means can be used. Further, as shown in FIG. 3, a light source 18 for detecting a color may be provided on the opposite side of the color detection unit 14 across the conveyance path of the recording medium S.

  The light energy curable ink jet recording apparatus 10 according to the present embodiment includes a tint detection unit 14 that detects the tint of an image by the ink droplets d1 ejected to the translucent part 42A. By doing so, it is possible to easily and more accurately detect the color of the image by using the color detection means 14 when performing color matching of the images. And if it is set as the structure which detects a color by the color detection means 14, compared with what observes a color by the user visually recognizing conventionally, color matching with high reliability can be performed. Therefore, stable color reproducibility can be ensured and high-quality drawing can be performed. In addition, it is possible to avoid the occurrence of loss such as printing out a number of recording media for color matching as in the past.

Next, the light transmission part formed in the conveyance belt of this embodiment is demonstrated.
FIG. 4 is a diagram illustrating an example of a light transmitting portion of the conveyance belt according to the present embodiment.
As shown in FIG. 4, in the configuration provided with the scanning type ink jet, the head unit 52 moves in the scanning direction, and the area where the ink is hit also moves in the scanning direction. At this time, the translucent part 42A can be configured to be formed at least partially in the width direction of the transport belt (left and right direction in FIG. 4).

  As shown in FIGS. 1 and 4, when performing color detection, the translucent part 42 </ b> A in which ink has been ejected in advance is moved to the front surface of the color detection means 14, and at this time, the translucent part 42 </ b> A detects When the detection light that has been transmitted and is in a position where the detected color can be detected by the color detection means 14, the detection light is applied to the ink applied in advance on the printing surface of the translucent portion 42A. Further, the color of the ink on the printing surface is detected by detecting the color by the color detecting means 14 through the light transmitting portion.

As shown in FIG. 4, the form in which the translucent portion is provided on the conveyor belt can be applied not only to the scanning head unit but also to the configuration of the full line head.
As shown in FIG. 4, if the transmission belt 42 is provided with the translucent portion 42 </ b> A, it is not necessary to provide the translucent portion 42 </ b> A on the majority of the conveyance belt 42. It can be secured sufficiently.

  Next, an example of a control system of the light energy curable ink jet recording apparatus of this embodiment will be described. FIG. 5 is a block diagram illustrating the control system of the present embodiment. FIG. 6 is a flowchart for explaining the procedure of color detection and color matching performed by the control of FIG.

  The ink jet recording apparatus 10 includes a control unit 21 that adjusts the driving conditions of the ink jet head. The color detection unit 14 outputs the detected detection value of the color to the control unit 21, and the control unit 21 adjusts the driving condition of the inkjet head 100 based on the detection value. In this way, if the color detection value is output to the control unit as an accurate information signal by the color detection means 14, the control unit 21 can accurately control the driving conditions of the inkjet head 100 based on the information signal. Will be able to.

  In addition, a lookup table L1 indicating the relationship of the drive voltage of the inkjet head 100 to the color density is input, and the computation unit 24 compares the lookup table L1 with the color of the image. It is preferable to adjust the driving conditions of the inkjet head 100.

  Further, in the present embodiment, when detecting the color of the ink applied to the transport belt translucent part 42A before printing on the recording medium S, the control unit 21 allows the translucent part 42A to transmit the detection light. Then, the position is moved so that the position can be detected by the color detection means 14. The control unit 21 is connected to a belt driving unit 26 that can drive and control the conveyance belt 42 in the conveyance direction to adjust the position of the light transmitting unit 42A. As the belt driving unit 26, belt rollers 44a, 44b, and 44c may be applied as shown in FIG. 1, or a member that drives and controls the conveyance belt may be applied separately.

  When performing color detection and color matching, first, ink is test-drawn on the transport belt translucent portion 42A (step S11).

  After the test drawing, the ink is cured by the ultraviolet irradiation unit 56, and the cured ink d1 is irradiated with light energy from the light source 18 for color detection (step S12), and the color detection is performed from the non-printing surface side of the recording medium S. The color of the image drawn on the printing surface of the translucent part 42A by the means 14 is detected (step S13).

  The color detection value detected by the color detection means 14 is output to the control unit 21. Then, the detected value is compared with the lookup table L1 input to the calculation unit 24 (step S14), and it is determined whether the detected color is appropriate (step S15). Here, the look-up table shows the relationship of the driving condition of the ink jet head with respect to the detected color density, and the look-up table shown in FIG. 7 can be used as an example. FIG. 7 shows a head drive voltage look-up table. In the look-up table shown in FIG. 7, the relationship between the head drive voltage (unit: volts) and the detected density of red (red) is shown as a correction curve. Based on this correction curve, it is possible to determine how much head driving voltage each of the plurality of inkjet heads (for example, heads 1 to 4 in FIG. 7) should be driven. In the lookup table, a correction curve related to driving conditions such as a head driving voltage may be set for blue and green (yellow, magenta, cyan, and black in the case of a subtractive color system).

  When it is determined that the detected color is inappropriate, the control unit 21 outputs a control signal to the inkjet head 100 to adjust the driving condition of the inkjet head 100 (step S16). Thus, after adjusting the driving conditions of the inkjet head 100, the test drawing is completed (step S17), and the main drawing based on the data on the recording medium S is started. If it is determined that the detected color is appropriate, the test drawing is completed without outputting a control signal from the control unit 21 to the inkjet head 100 (step S17), and the main drawing on the recording medium S is completed. To start.

  In this way, if the lookup table L1 is prepared in advance, when actually performing color matching, the actual measured value of the color of the image detected by the color detection means and the lookup table L1 are obtained. By comparing, the drive voltage of the inkjet head 100 to be set in order to obtain a desired color can be determined, and the color matching is performed more accurately by controlling the inkjet head 100 by the control unit according to this drive voltage. And color reproducibility can be improved.

[Ink composition]
The ink composition used in the present invention is an ink composition that can be cured by irradiation with light energy, and examples thereof include a cationic polymerization ink composition, a radical polymerization ink composition, and a water-based ink composition.

  The “light energy” as used in the present invention is not particularly limited as long as it can give energy capable of generating a starting species in the ink composition by irradiation, and is broadly divided into α rays, γ rays, X-rays, ultraviolet rays, visible rays and the like are included. Among these, ultraviolet rays are preferable from the viewpoint of curing sensitivity and device availability. 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 energy 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 It is suitable that it is 450 nm. The (a) electron transfer start system of the ink composition of the present invention has sufficient sensitivity even with low output light energy. Therefore, the output of light energy is, for example, 2,000 mJ / cm ² or less, preferably 10 to 2,000 mJ / cm ² , more preferably 20 to 1,000 mJ / cm ² , and still more preferably 50 to 800 mJ. An irradiation energy of / cm ² is appropriate. Also, light energy, exposure surface illuminance (the maximum illuminance of the surface of the recording medium) is, for example, 10 to 2,000 mW / cm ^2, preferably, suitably be irradiated at 20 to 1,000 mW / cm ² is there.
In particular, in the ink jet recording apparatus of the present invention, the light energy 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. The light emitting diode is preferably irradiated.

In the inkjet recording apparatus of the present invention, it is appropriate that light energy is applied to the ink composition ejected on the recording medium, for example, for 0.01 to 120 seconds, preferably 0.1 to 90 seconds. It is.
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 to the recording medium to the irradiation of light energy is 0.01 to 0.5 seconds. Preferably, the time is 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 energy in an extremely short time, it is possible to prevent the landed ink composition from bleeding before curing. .

  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, the active energy can easily reach the lower ink, and good curing sensitivity, reduction of residual monomers, reduction of odor, and improvement of adhesion can be expected. In addition, although irradiation with light energy can be performed by injecting all colors and exposing them together, exposure for each color is preferable from the viewpoint 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, since the light energy curable ink such as the ink composition of the present invention desirably has a constant temperature for the ink composition to be ejected, from the ink supply tank to the inkjet head portion, It is preferable to perform temperature control by heat insulation and heating. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

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

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

[Recording medium]
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and a resin film having ordinary translucency can be used. For example, a PET film, an OPS film, an OPP film, an ONy film, A PVC film, a PE film, a TAC film, etc. can be mentioned. In addition, examples of the plastic that can be used as a recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. In addition, translucent media or glass deposited with metal can be used as a recording medium.

  The cationic polymerization ink composition, radical polymerization ink composition, and water-based ink composition that can be used in the present invention 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 active light energy. 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 by irradiation with active light energy, which will be described later, and cures. In addition, 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 its alkylene oxide adducts, and novolak-type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

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

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

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

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

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

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

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

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

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

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

The compound having such an oxetane ring is described in detail in the above-mentioned JP-A No. 2003-341217, paragraph numbers [0021] to [0084], and the compounds described herein 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 energy]
The ink composition of the present invention contains a compound that generates an acid when irradiated with light energy (hereinafter, appropriately referred to as “photoacid generator”).
Examples of the photoacid generator that can be used in the present invention include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, and light used for microresists. A compound that generates an acid upon irradiation with ultraviolet rays (400 to 200 nm, far ultraviolet rays, particularly preferably g-line, h-line, i-line, KrF excimer laser beam), ArF excimer laser beam, and the like is appropriately selected and used. be able to.

  Examples of such a photoacid generator include an onium salt such as a diazonium salt, an ammonium salt, a phosphonium salt, an iodonium salt, a sulfonium salt, a selenonium salt, and an arsonium salt, which decomposes upon irradiation with light energy to generate an acid. Organic halogen compounds, organic metal / organic halides, photoacid generators having an o-nitrobenzyl-type protecting group, compounds that generate sulfonic acids by photolysis, such as iminosulfonates, disulfone compounds, diazoketo A sulfone and a diazo disulfone compound can be mentioned.

  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. When the pKa is smaller than 2, the stability of the ink composition with time is deteriorated. 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.
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. 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 orange, 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 weight copolymer, a modified polyacrylate, an aliphatic Examples thereof include polyvalent carboxylic acids, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, and pigment derivatives. It is also preferable to use a commercially available polymer dispersant such as the Solsperse series from Zeneca.
Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  In the ink composition, as a dispersion medium for various components such as pigments, a solvent may be added, or the solvent-free low molecular weight component (a) cationic polymerizable compound may be used as a dispersion medium. However, the ink composition of the present invention is a radiation curable ink, and is preferably solventless in order to cure the ink after it is applied to a recording medium. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a 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.
The selection of pigment, dispersant, dispersion medium, dispersion conditions, and filtration conditions are set so that the average particle diameter of the pigment particles is within the above-mentioned preferable 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. Therefore, a so-called water-insoluble oil-soluble dye is 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 paragraph numbers [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 mentioned as preferable examples, and specific examples include paragraph numbers [0052] to [0066] of JP-A No. 2001-181547. Examples thereof include the compounds described in paragraph Nos. [0079] to [0081] of JP-A No. 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. 5-194433, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492 and 56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in No. 24239, compounds that emit ultraviolet light by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, so-called fluorescent brighteners, and the like.
Although the addition amount is appropriately selected according to the purpose, it is generally about 0.5 to 15% by mass in terms of solid content.

[Sensitizer]
If necessary, a sensitizer may be added to the ink composition of the present invention for the purpose of improving the acid generation efficiency of the photoacid generator and increasing the photosensitive wavelength. Any sensitizer may be used as long as the photoacid generator is sensitized by an electron transfer mechanism or an energy transfer mechanism. Preferably, aromatic polycondensed compounds such as anthracene, 9,10-dialkoxyanthracene, pyrene and perylene, aromatic ketone compounds such as acetophenone, benzophenone, thioxanthone and Michlerketone, and heterocyclic compounds such as phenothiazine and N-aryloxazolidinone Is mentioned. The addition amount is appropriately selected depending on 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 Patent No. 223739, No. 309401, No. 309402, No. 310551, No. 310552, No. 4594416, German Published Patent No. 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. % 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 dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.

In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to inhibit the adhesion to recording media such as polyolefin and PET, and the like, The tackifier which does not do can be contained.
As the tackifier, specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, 5-6p (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms). An ester with an alcohol having, an ester of (meth) acrylic acid with an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid with an aromatic alcohol having 6 to 14 carbon atoms) And 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, so that it falls within the above range. It is preferable to adjust the composition ratio appropriately. The ink viscosity at 25 to 30 ° C. is 35 to 500 mPa · s, preferably 35 to 200 mPa · s. By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be prevented, uncured monomer can be reduced, and odor can be reduced. Dot bleeding at the time of landing can be suppressed, and as a result, the image quality is improved. If the ink viscosity at 25 to 30 ° C. is less than 35 mPa · s, the effect of preventing bleeding is small, and conversely if it is greater than 500 mPa · s, there is a problem in the delivery of the ink liquid.

  The surface tension of the ink composition of the present invention is preferably 20 to 30 mN / m, more preferably 23 to 28 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and non-coated 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 energy and cured to perform recording.
In the printed matter obtained with this ink, the image portion is cured by irradiation with light energy such as ultraviolet rays, and the strength of the image portion is excellent.

[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 the compound having an addition polymerizable ethylenically unsaturated bond that can be used in the ink composition of the present invention include unsaturated carboxylic acids (for example, 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 be mention | raise | lifted. Specific examples of an amide monomer of an aliphatic polyvalent amine compound and an unsaturated carboxylic acid 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.

Other examples include vinyls containing a hydroxyl group represented by the following general formula (A) in a polyisocyanate compound having two or more isocyanate groups per molecule described in JP-B-48-41708. Examples thereof include a vinylurethane compound 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 can 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]
Furthermore, 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 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. Examples thereof 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, etc. Resin, rubber resin, wax and the like can be appropriately selected and used. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to contain a tackifier that does not inhibit the polymerization. Specifically, high molecular weight adhesive polymers described in JP-A-2001-49200, 5-6p (for example, esters of (meth) acrylic acid and alcohols having an alkyl group having 1 to 20 carbon atoms) , An ester of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer formed of an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms), A low molecular weight tackifying resin having a saturated bond.

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

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

In the 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 color material, the concentration of the polymerization initiator and the polymerizable substance in the ink can be adjusted in accordance with the absorption characteristics of the contained color material. preferable. As described above, the amount of water or solvent is in the range of 40% to 90%, preferably 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% on the mass basis with respect to the total amount of the ink. Although the polymerization initiator depends on the content of the polymerizable compound, it 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.

1 is a schematic configuration diagram of a light energy curable ink jet recording apparatus according to the present invention. It is a figure explaining a conveyance mechanism. It is a schematic diagram explaining the state which forms an image on a recording medium. It is a figure explaining an example of the translucent part of the conveyance belt of this embodiment. It is a block diagram explaining an example of the control system of a light energy curing type inkjet recording device. It is a flowchart explaining the process of the color detection performed by control of FIG. 5, and a color matching. 2 shows a head drive voltage lookup table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light energy curable inkjet recording device 14 Color detection means 21 Control part 24 Calculation part 42A Translucent part 52 Head unit 56 Ultraviolet irradiation part (energy irradiation means)
D Ink d1 Ink droplet L1 Look-up table S Translucent recording medium

Claims (5)

An ink jet head that ejects ink that is cured by irradiation with light energy onto a translucent recording medium;
A transport belt for transporting the translucent recording medium;
Energy irradiating means for irradiating light energy onto a printing surface on which the ink of the translucent recording medium is ejected;
A color detecting means for detecting the color of the ink;
At least a part of the transport belt is provided with a translucent part capable of transmitting detection light, and ink is landed on the translucent part at the time of color detection, and the landed ink passes through the translucent part to the color tint. A light energy curable ink jet recording apparatus characterized by detecting by a detecting means.   When detecting the color of the ink landed on the translucent part, the translucent part is controlled so that the translucent part moves to a position where the detection light can be detected by the tint detecting means. The light energy curable ink jet recording apparatus according to claim 1, further comprising a control unit.   3. The light energy curable ink jet recording apparatus according to claim 1, further comprising a cleaning unit which is formed so as to be in contact with the light transmitting part of the transport belt and which cleans the surface of the light transmitting part. .   4. The light energy according to claim 1, further comprising a control unit configured to adjust a driving condition of the inkjet head based on a color detection value obtained by the color detection unit. 5. A curable ink jet recording apparatus.   A calculation unit to which a look-up table indicating a relationship of the drive voltage of the inkjet head with respect to the color density is input; the calculation unit compares the look-up table with the color of the image; The light energy curable ink jet recording apparatus according to claim 1, wherein a driving condition is adjusted.

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