JP2008173850A - Ultraviolet-curable inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet apparatus which has a high fixing speed and a high productivity, can record on various recording media, and is compact and at a low cost. <P>SOLUTION: In the inkjet apparatus 10 having a recording medium conveying means for conveying a recording medium, a full line inkjet head which delivers an ink curable by irradiating the recording medium conveyed by the recording medium conveying means with ultraviolet rays based on an image signal and has approximately the same length as the width of the recording medium, and ultraviolet irradiating means for curing the ink delivered on the recording medium by the full line head, two hot-cathode tubes 14 with an angle of aperture of 45-180° are arranged by relatively shifting them each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultraviolet curable ink jet recording apparatus, and more particularly to an ultraviolet curable ink jet apparatus having a hot cathode tube.

Inkjet devices that perform image formation by ejecting ink that is cured by energy such as ultraviolet rays and electron beams onto a recording medium using an inkjet head and curing the ink by energy irradiation are environmentally friendly and can be applied to various recording media at high speed. It has features such that it can be recorded and a high-definition image that is difficult to bleed can be obtained.
In particular, an apparatus using ultraviolet curable ink has been developed from the viewpoint of easy handling of a light source and compactness. In particular, using a web-like recording medium capable of high-speed conveyance utilizing its high-speed fixing property, the recording medium is disposed facing the recording medium in a state where a recording head having a full width is fixed. A so-called single-pass ink jet apparatus has been devised in which recording is completed only by passing under the head once.
When color printing is performed with this single-pass ink jet apparatus, fixed heads for the number of colors are arranged in the conveyance direction of the recording medium. In this case, in order to prevent mixing of different color inks, Patent Document No. 1 discloses an apparatus in which a light irradiation means is disposed downstream of each color head.
Patent Document 2 discloses an inkjet system that uses a cationic ultraviolet curable ink and uses an inexpensive cold cathode fluorescent tube and hot cathode fluorescent tube.
JP 2004-314586 A JP 2004-237602 A

  FIG. 6 shows an inkjet apparatus described in Patent Document 1 which is a single-pass inkjet system. In the figure, 60 is a conventional single-pass ink jet apparatus. In the single-pass inkjet device 60, the recording medium S is pulled out from the recording medium roll 61 wound in a roll shape, and first, a Y (yellow) color full-line inkjet in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S. While transporting under the head 63Y, the Y color ink is recorded on the recording medium S in a desired image form, and the Y color ink of the ultraviolet curable ink ejected onto the recording medium S is immediately after that for active energy curing. While passing under the lamp 64, it is fixed by receiving active energy. A strong light intensity is required to cure the ink, and very expensive high-pressure mercury lamps, medium-pressure mercury lamps, and metal halide lamps are used as light sources.

  Next, a UV-curable M-color ink is transferred onto the recording medium S while the ink is transported under the M (magenta) full-line inkjet head 63M in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S. The M color ink recorded in this manner and discharged onto the recording medium S is fixed immediately after receiving the active energy while passing under the active energy curing lamp 64.

  Further, the ultraviolet curable C-color ink is applied to the desired label on the recording medium S while being conveyed under the C (cyan) full-line inkjet head 63C in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S. Immediately thereafter, the C-color ink recorded in the image form and discharged onto the recording medium S is fixed by receiving active energy while passing under the active energy curing lamp 64.

  Finally, ultraviolet curable B-color ink is conveyed under the B (black) full-line inkjet head 63B in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S (perpendicular to the paper surface in the figure). Is recorded on the recording medium S like an image of a desired label, and the B color ink ejected to the recording medium S immediately after that is a metal halide lamp 65 having a light intensity higher than that of the active energy curing lamp 64 so far. The four colors are fixed by receiving the active energy while passing under and recording with the four colors of ink is performed.

As described above, the ultraviolet curable ink is applied to the single-pass inkjet device because of its excellent high-speed fixability, has high productivity, can be drawn on various recording media, and is environmentally friendly. Several systems have been launched that have advantages.
On the other hand, strong light intensity is required to cure the ink, and as a light source for ink curing, a very expensive high-pressure mercury lamp, medium-pressure mercury lamp, metal halide lamp, or the like has been conventionally used.

FIG. 7 shows an inkjet apparatus described in Patent Document 2 using an inexpensive hot cathode fluorescent tube.
In the figure, 70 is a carriage type ink jet device, 71 is a platen, 73 is an ink jet nozzle, 73Y is yellow, 73M is magenta, 73C is cyan, 73B is black, 74 is an inexpensive hot cathode fluorescent tube, 75 Is a driving device that scans the inkjet nozzle 73 and the hot cathode fluorescent tube 74 together in the width direction (X direction in the figure) of the recording medium S. The recording medium S has recorded and fixed four colors in one scan, and then moved by the recording width of the inkjet nozzle 73 in the vertical direction (Y direction in the figure) on the paper surface, and starts the next scan again. .

  Thus, according to the invention described in Patent Document 1, in a highly productive apparatus, it is necessary to increase the irradiation intensity as the light irradiation time is shortened. In order to prevent mixing, there is a drawback that the device becomes very expensive, and according to the invention described in Patent Document 2, since it is not a single pass, the curability under high speed conditions is not sufficient. There were drawbacks.

  The present invention has been made in order to solve the above-described problems, and provides a compact and inexpensive inkjet apparatus that can increase the fixing speed to increase the productivity, record on various recording media. It is aimed.

In order to achieve the above object, the invention according to claim 1 relates to an ink jet apparatus, wherein a recording medium transporting means for transporting a recording medium, and ultraviolet irradiation to the recording medium transported by the recording medium transporting means. A full-line inkjet head having a length substantially the same as the width of the recording medium that ejects ink curable by the image signal based on the image signal, and an ultraviolet irradiation means that cures the ink ejected onto the recording medium by the full-line head. The ultraviolet irradiation means includes an aperture type hot cathode tube.
According to a second aspect of the present invention, in the ink jet apparatus according to the first aspect, the aperture hot cathode tube has an aperture angle of not less than 45 ° and not more than 180 °.
According to a third aspect of the present invention, in the ink jet apparatus according to the second aspect, the plurality of hot cathode tubes are arranged with their positions in the recording medium width direction relatively shifted.
According to a fourth aspect of the present invention, in the ink jet apparatus according to the second or third aspect, the plurality of hot cathode tubes are arranged in parallel to each other, and the thickness tendency of the fluorescent paint film thickness of the hot cathode tubes is opposite to each other. It arranges so that it becomes.

According to a fifth aspect of the present invention, in the ink jet apparatus according to the first or second aspect, the ultraviolet irradiation means includes a plurality of aperture type hot cathode tubes, and each of the plurality of hot cathode tubes has a different distance to the irradiation surface. It is characterized by that.
The invention according to claim 6 is the ink jet apparatus according to claim 1 or 2, wherein the ultraviolet irradiation means includes a plurality of aperture type hot cathode tubes, and the central emission wavelengths of the plurality of hot cathode tubes are different from each other. It is said.

  According to the above configuration, it is possible to obtain an inkjet apparatus that is fast in fixing speed, high in productivity, can be recorded on various recording media, and is compact and inexpensive.

  Hereinafter, the present invention will be described based on an embodiment of an ink jet apparatus.

1A and 1B are schematic diagrams of an inkjet apparatus according to Embodiment 1 of the present invention, and FIG. 1B is a sectional view of an aperture type hot cathode tube used in FIG.
In FIG. 1, 10 is a single-pass ink jet apparatus according to the first embodiment, 11 is a recording medium roll, 12 is a take-up roll, 13 is a full-line ink jet head, and 14 is an active energy curing lamp. A tube, 15 is a metal halide lamp, and 16 is a cooling fan.
In the single-pass inkjet device 10, the recording medium S is pulled out from the recording medium roll 11 wound in a roll shape, and after recording and fixing are repeated for each color, the recording medium S is wound around the winding roll 12. First, while transporting under the Y (yellow) full-line inkjet head 13Y in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S, Y-color ink is recorded on the recording medium S in a desired image manner, Immediately thereafter, the Y-color ink of ultraviolet curable ink discharged onto the recording medium S is pinned by receiving active energy while passing under the aperture type hot cathode tube 14.

  Next, a UV-curable M-color ink is transferred onto the recording medium S while it is transported under the M (magenta) full-line inkjet head 13M in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S. The M color ink recorded in this manner and discharged onto the recording medium S is immediately pinned by receiving active energy while passing under the aperture type hot cathode tube 14.

  Further, a UV-curable C-color ink is applied to the desired label on the recording medium S while it is conveyed under the C (cyan) full-line inkjet head 13C in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S. Immediately thereafter, the C color ink recorded in the image form and discharged onto the recording medium S is pinned by receiving active energy while passing under the aperture type hot cathode tube 14.

  Finally, ultraviolet curable B-color ink is conveyed under the B (black) full-line inkjet head 13B in which a large number of inkjet nozzles are arranged in the width direction of the recording medium S (perpendicular to the paper surface in the figure). Is recorded on the recording medium S like an image of a desired label, and the B color ink discharged to the recording medium S is irradiated with the optical fiber 19 immediately after passing under the metal halide lamp 15 with high light intensity. As a result, irradiation is performed uniformly, the four colors are fixed by receiving the active energy, and the recording with the four colors of ink is performed.

Here, the aperture type hot cathode tube 14 will be described.
Aperture-type hot cathode fluorescent lamps have a structure in which an aperture that is not coated with a fluorescent material is provided on a part of the inner wall of the glass tube of the hot cathode fluorescent lamp to radiate light intensively and achieve high output. ing. FIG. 1B shows a sectional view of an aperture type hot cathode tube.
In FIG. 2B, the phosphor 14a is applied to the inside of the glass tube of the aperture type hot cathode tube 14, but the lower range of the angle θ in the figure is not applied in the tube axis direction.
The range of the uncoated portion is preferably a range where the central angle (aperture angle) θ is 45 ° to 180 ° in a cross section perpendicular to the tube axis, and if it is less than this, the light irradiation range becomes narrow, so the light energy necessary for pinning is reduced. If it is larger than this, the light irradiation range is widened and the aperture effect is weakened.

  As described above, according to the first embodiment, since the aperture type hot cathode tube is used, the energy output is high, the pinning speed can be increased, the productivity is high, and the recording is possible on various recording media. Since the aperture type hot cathode tube is much cheaper and smaller than the conventional high pressure mercury lamp, a compact and inexpensive ink jet apparatus can be obtained.

2A and 2B are diagrams for explaining a second embodiment of the present invention. FIG. 2A is a perspective view of an aperture type hot cathode tube constituting a light irradiation unit according to the second embodiment, and FIG. 2B is an aperture type of FIG. It is the front view (I) and the top view (B) of an edge part of a hot cathode tube. (C) is a front view (a) and an end plan view (b) showing an aperture type hot cathode tube of the arrangement normally considered.
The second embodiment is an invention in which two aperture type hot cathode tubes are arranged on the same plane. In the figure, 14-1 is a first aperture type hot cathode tube, 14-2 is a second aperture type hot cathode tube, and 14s is a socket part of each aperture type hot cathode tube. Since the diameter of the socket 14s is larger than the diameter of the glass portion, a large gap t2 between the glass tubes 14-1 and 14-2 when the socket portions 14s are arranged side by side so as to contact each other as shown in (c). As a result, the light intensity distribution in the transport direction becomes uneven, and the length in the transport direction becomes longer.
On the other hand, as shown in (a) and (b), the socket portions 14s are shifted from each other so that one socket 14s is in contact with the other glass tube (in the drawing, the socket of the second aperture type hot cathode tube 14-2). 14s is in contact with the glass tube of the first aperture type hot cathode tube 14-1), the gap t1 between the glass tubes 14-1 and 14-2 becomes small, and the light intensity distribution in the transport direction And the length in the transport direction is shortened.

  Further, the correlation between the light intensity at the portion of the reflecting mirror R and the light intensity on the recording medium S is examined in advance, and a light sensor for detecting the light intensity is attached to the portion of the reflecting mirror R that does not obstruct light irradiation, If the light intensity signal from the optical sensor is fed back to the inverter that is the power source of the hot cathode tube, the light intensity of the light source can be kept constant. That is, the actual light intensity on the recording medium S is obtained from the light intensity signal from the optical sensor based on the correlation, and when this is weaker than the predetermined light intensity, the output of the inverter is increased. If the light intensity is too high, the output of the inverter is increased so that the light intensity of the light source can be kept constant.

FIGS. 3A and 3B are diagrams for explaining a third embodiment of the present invention. FIG. 3A is a sectional view taken along the axial direction of the glass tube of the aperture type hot cathode tube targeted by the third embodiment, and FIG. The perspective view of a hot cathode tube, (c) is a top view of the edge part of an aperture type hot cathode tube.
Although the third embodiment will be described based on the second embodiment, it is not necessarily an invention applicable only to the second embodiment. In FIG. 1A, the phosphor 14F is applied to the inside of the glass tube of the aperture type hot cathode tube. The thickness of the coating layer of the phosphor 14F is caused by the manufacturing method. As shown by the arrow K1, there is a tendency to become thicker from one side to the other (because the glass tube is immersed vertically in the phosphor liquid and pulled up vertically, the phosphor liquid adhering to the glass tube falls due to gravity. Therefore, in the vertical direction, it is considered that the upper part is thin and the lower part is thin). Therefore, if the thickness of the coating layer of the phosphor 14F is different, naturally the light intensity emitted therefrom is also different.
The third embodiment is an invention for correcting the manufacturing defect of the aperture type hot cathode tube. As shown in FIG. 2B, two aperture type hot cathode tubes 14-1 and 14-2 are formed according to the second embodiment. When juxtaposed, the thickness tendency K1 of the coating layer of the cathode tube 14-1 and the thickness tendency K2 of the coating layer of the cathode tube 14-2 are arranged opposite to each other. . By doing so, the light intensity characteristic of the cathode tube 14-1 and the light intensity characteristic of the cathode tube 14-2 are complemented to obtain a uniform light intensity characteristic as a whole, and a light source favorable for pinning can be obtained.

4A and 4B are diagrams for explaining a fourth embodiment of the present invention, in which FIG. 4A is a perspective view showing an arrangement relationship of two aperture type hot cathode tubes according to the fourth embodiment, and FIG. 4B is an aperture type of FIG. It is the front view (I) and the top view (B) of an edge part of a hot cathode tube.
In Example 4, as can be seen in FIGS. 4A and 4B, the vertical height of the aperture type hot cathode tube 14-1 from the recording medium S is H1, and the aperture type hot cathode tube 14-2 has the same height. It is characterized in that H2 (H1> H2) and the vertical height from the recording medium S is different. The recording medium S is conveyed in the direction of arrow H in the figure. That is, in the recording medium S, the ink is hardened weakly by the light of the hot cathode tube 14-1 having a long distance first, and then further hardened by the light of the near hot cathode tube 14-2. By doing so, the ink is suddenly heated suddenly, so that thermal distortion does not occur and good pinning is performed.

  As a modification of the fourth embodiment, instead of changing the distance, the distance may be the same and the light intensity of the two aperture type hot cathode tubes may be different (the first one is weakened).

5A and 5B are diagrams for explaining a fifth embodiment of the present invention. FIG. 5A is a perspective view of two aperture type hot cathode tubes according to the fourth embodiment, and FIG. 5B is a perspective view of the aperture type hot cathode tube of FIG. They are a front view (A) and a plan view (B) of an end.
The fifth embodiment is characterized in that two aperture-type hot cathode fluorescent lamps having different wavelengths of light λ are juxtaposed according to the second embodiment. For example, the wavelength λ of the first aperture type hot cathode tube 14-1 is 365 nm, and the wavelength λ of the second aperture type hot cathode tube 14-2 is 320 nm.
By doing so, light with a short wavelength λ (λ = 320 nm) is less likely to go into the ink, and thus contributes to the curing of the ink surface, whereas light with a long wavelength λ (λ = 365 nm) Since it is easy to go to the inside of the ink, by mainly taking charge of the internal curing of the ink, according to the fifth embodiment, it is possible to uniformly cure the ink inside and outside.

  As described above, according to the present invention, it is possible to obtain a compact and inexpensive ink jet apparatus that can increase the fixing speed, increase the productivity, and record on various recording media.

  The UV ink composition is preferably an ink composition that can be cured by irradiation with active energy.

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

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

In the inkjet apparatus of the present invention, it is appropriate that the active energy is applied to the ink composition ejected on the recording medium, for example, for 0.01 to 120 seconds, preferably for 0.1 to 90 seconds. is there.
Furthermore, in the ink jet 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 irradiation of the active energy is 0.01 to 0.5 seconds. Preferably, the time is 0.02 to 0.3 seconds, more preferably 0.03 to 0.15 seconds. Thus, by controlling the time from the landing of the ink composition to the recording medium to the irradiation of the active energy to an extremely short time, it is possible to prevent the landed ink composition from bleeding before curing. .

  In addition, in order to obtain a color image using the inkjet 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 active energy can be performed by injecting all the colors and exposing them together, exposure for each color is preferable from the viewpoint of promoting curing.

  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 1 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 active 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 cartridge 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.

〔recoding media〕
The label recording medium used in the present invention is not particularly limited, and covers various kinds of non-absorbent resin materials used for ordinary non-coated paper, coated paper, and so-called soft packaging as a cover, or in the form of a film. A molded resin film 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.

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

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

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

Examples of the epoxy compound include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides.
Aromatic epoxides include di- or polyglycidyl ethers produced by the reaction of polyphenols having at least one aromatic nucleus or their alkylene oxide adducts and epichlorohydrin, such as bisphenol A or its alkylene oxides. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or 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 active energy]
The ink composition of the present invention contains a compound that generates an acid upon irradiation with radiation (hereinafter, appropriately referred to as “photoacid generator”).
Examples of the photoacid generator that can be used in the present invention include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, and light used for microresists. (Irradiation of active energy of 400 to 200 nm, active energy, 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 A compound that generates an acid can be appropriately selected and used.

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

[(C) Colorant]
The ink composition of the present invention can form a visible image by adding a colorant. For example, when forming an image area of a lithographic printing plate, it is not always necessary to add it, but it is also preferable to use a colorant from the viewpoint of plate inspection of the obtained lithographic printing plate.
There is no restriction | limiting in particular in the coloring agent which can be used here, According to a use, well-known various coloring agents, (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 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 cation polymerizable compound is used, and among them, it is preferable to select a cation polymerizable monomer having the lowest viscosity in terms of dispersion suitability and handling property 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 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.
The addition amount is appropriately selected according to the purpose, but 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, 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 at page 527, ibid. 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. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, a copolymer containing “carboxyl group-containing monomer”, “methacrylic acid alkyl ester”, or “acrylic acid alkyl ester” as a structural unit is also preferably used as the copolymer composition of the polymer binder.

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

In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to inhibit the adhesion to recording media such as polyolefin and PET, and the like, The tackifier which does not do can be contained.
As 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.

  The surface tension of the ink composition of the present invention is preferably 20 to 40 mN / m, more preferably 25 to 35 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and uncoated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and the wettability is preferably 40 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 radiation and cured to perform recording.
In the printed matter obtained with this ink, the image portion is cured by irradiation with radiation such as active energy, and the strength of the image portion is excellent. Therefore, in addition to image formation with ink, for example, an ink receiving layer ( It can be used for various purposes such as formation of an image portion.

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

[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 also 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. CH2 = C (R) COOCH2CH (R ') OH (A) (where R and R' represent H or CH3)
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% with respect to all the components of the ink composition (where% is used herein) Mass%).

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

  Preferred polymerization initiators include (i) aromatic ketones, (ii) aromatic onium salt compounds, (iii) organic peroxides, (iv) hexaarylbiimidazole compounds, (v) ketoxime ester compounds, (vi ) Borate compounds, (vii) azinium compounds, (viii) metallocene compounds, (ix) active ester compounds, (x) compounds having a carbon halogen bond, and the like.

[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 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. 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. % Range.

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

[Water-based ink composition]
The aqueous ink composition contains a polymerizable compound and a water-soluble photopolymerization initiator that generates radicals by the action of radiation. If desired, it may further contain a colorant 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 in consideration of end-operator characteristics such as curing speed, adhesion, and flexibility. Examples of such reactive materials include (meth) acrylate (ie, acrylate and / or methacrylate) monomers and oligomers, epoxides, and oxetanes.
Examples of acrylate monomers include phenoxyethyl acrylate, octyl decyl acrylate, tetrahydrofuryl acrylate, isobornyl acrylate, hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate (e.g., tetraethylene glycol). Diacrylate), dipropylene glycol diacrylate, tri (propylene glycol) triacrylate, neopentyl glycol diacrylate, bis (pentaerythritol) hexaacrylate, ethoxylated or propoxylated glycol and polyol acrylate (e.g. propoxylated neopentyl glycol Diacrylate, ethoxylated trimethylol proppant Acrylate), and mixtures thereof.
Examples of acrylate oligomers include ethoxylated polyethylene glycol, ethoxylated trimethylolpropane acrylate and polyether acrylate and ethoxylates thereof, and urethane acrylate oligomers.
Examples of methacrylates include hexanediol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and mixtures thereof.
The amount of oligomer added is preferably 1 to 80% by weight, more preferably 1 to 10% by weight, based on the total weight of the ink composition.

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

   Further, in the present invention, a water-soluble derivative (hereinafter abbreviated as an 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 colorant as described above. 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 colorant. Clear inks that do not contain colorants can be used for undercoating to give recording materials suitable for image printing, or for surface protection of images formed with ordinary ink, for 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.

  As prescription conditions when applied to such a clear ink, the water-soluble polymerizable compound as a main component of the ink is 10 to 85%, a photopolymerization initiator (for example, an active energy polymerization catalyst), and the water-soluble compound described above. It is preferable to prepare such that 1 to 10 parts by mass with respect to 100 parts by mass of the polymerizable compound and, at the same time, at least 0.5 part of the photopolymerization initiator is contained with respect to 100 parts of ink.

[Material composition in colorant-containing ink]
When the above-described water-soluble polymerizable compound is used in an ink containing a colorant, the concentration of the polymerization initiator and the polymerizable substance in the ink can be adjusted in accordance with the absorption characteristics of the colorant contained. 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 colorant 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 density used for general color coloring.

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

BRIEF DESCRIPTION OF THE DRAWINGS It is an inkjet apparatus which concerns on Example 1 of this invention, (a) is the apparatus conceptual diagram, (b) is sectional drawing of the aperture type hot cathode tube used by (a). It is a figure explaining Example 2 of this invention, (a) is a perspective view of the aperture type hot cathode tube which comprises the light irradiation part which concerns on Example 2, (b) is an aperture type hot cathode tube of (a). They are a front view (A) and a plan view (B) of an end. (C) is a front view (a) and an end plan view (b) showing an aperture type hot cathode tube of the arrangement normally considered. It is a figure explaining Example 3 of this invention, (a) is sectional drawing along the axial direction of the glass tube of the aperture type hot cathode tube which Example 3 is object, (b) is an aperture type hot cathode tube A perspective view and (c) are plan views of the end portion of the aperture type hot cathode tube. FIG. 6 is a diagram for explaining a fourth embodiment of the present invention, in which (a) is a perspective view showing the arrangement relationship of two aperture type hot cathode tubes according to the fourth embodiment, and (b) is a diagram of the aperture type hot cathode tube of (a). They are a front view (A) and a plan view (B) of an end. FIG. 6 is a diagram for explaining a fifth embodiment of the present invention, where (a) is a perspective view of two aperture type hot cathode tubes according to the fourth embodiment, and (b) is a front view of the aperture type hot cathode tube of FIG. ) And a plan view (b) of the end portion. This is an inkjet apparatus described in Patent Document 1 which is a single-pass inkjet system. An ink jet apparatus described in Patent Document 2 using an inexpensive hot cathode fluorescent tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Single-pass inkjet apparatus 11 which concerns on this invention Recording medium roll 12 Winding roll 13 Full line inkjet head 14 Aperture type hot cathode tube 14-1 1st aperture type hot cathode tube 14-2 2nd aperture type Hot cathode tube 15 Metal halide lamp 16 Cooling fan S Recording medium

Claims (6)

The width of the recording medium for discharging the recording medium based on the image signal, the recording medium conveying means for conveying the recording medium, and the ink curable by irradiating the recording medium conveyed by the ultraviolet ray with the ultraviolet rays In an inkjet apparatus having a full-line inkjet head having the same length and an ultraviolet irradiation means for curing ink ejected onto a recording medium by the full-line head,
An ink jet apparatus, wherein the ultraviolet irradiation means includes an aperture type hot cathode tube.   The inkjet apparatus according to claim 1, wherein the aperture type hot cathode tube has an aperture angle of 45 ° or more and 180 ° or less.   3. The ink jet apparatus according to claim 2, wherein the plurality of hot cathode tubes are arranged with their positions in the recording medium width direction relatively shifted.   4. The inkjet according to claim 2, wherein the plurality of hot cathode tubes are arranged in parallel to each other, and the thickness tendency of the fluorescent paint film thickness of the hot cathode tubes is opposite to each other. apparatus.   3. An ink jet apparatus according to claim 1, wherein said ultraviolet irradiation means includes a plurality of aperture type hot cathode tubes, and each of the plurality of hot cathode tubes has a different distance to the irradiation surface.   3. The ink jet apparatus according to claim 1, wherein the ultraviolet irradiation means includes a plurality of aperture type hot cathode tubes, and the center emission wavelengths of the plurality of hot cathode tubes are different from each other.

Images