JP2007021958A - Active energy curing ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy curing ink jet recorder excellent in productivity in which high definition drawing can be carried out by preventing a foreign substance such as dust or paper powder from adhering to the vicinity of the nozzle in an ink jet head. <P>SOLUTION: The ink jet recorder comprises a means for irradiating active energy, an ink jet head ejecting ink which can be cured with active energy irradiated by the active energy irradiation means toward a recording medium, wherein a means for conveying the recording medium to a position opposing the ink jet head is further provided with a pressure regulation means for sustaining the pressure in the ink jet recorder higher than the pressure on the outside of the ink jet recorder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an active energy curable ink jet recording apparatus that forms an image on a recording medium by ink jet using ink that is cured by active energy such as ultraviolet rays and electron beams, and in particular, is an activity that is difficult for an ink jet head to fail. The present invention relates to an energy curable ink jet recording apparatus.

An active energy curable ink jet apparatus that forms an image by ejecting ink that is cured by active energy such as an electron beam or ultraviolet light onto a recording medium using an ink jet head and curing the ink by irradiation of the active energy is environmentally friendly. It has features such as high-definition images that can be recorded on various recording media at high speed and that are difficult to bleed (see, for example, Patent Document 1).
JP2003-200244A

4A and 4B are schematic diagrams of a configuration of an active energy curable ink jet recording apparatus of a conventional belt conveyance type full line head system, where FIG. 4A is a front view and FIG. 4B is a side view of the full line head portion. Yes.
Hereinafter, the active energy curable ink jet recording apparatus of FIG. 4 will be briefly described.
In the figure, reference numeral 400 denotes an active energy curable ink jet recording apparatus. In the housing 12 of the active energy curable ink jet recording apparatus 400, there are a recording medium storage unit 20, a transport unit 30, a scanning transport unit 40, and an image recording unit 50 that performs image recording and ultraviolet light irradiation fixing. And a tray 90 to which the recording medium S is sent out.

  In the recording medium storage unit 20, a storage cassette 22 is detachably disposed at the bottom of the housing 12.

  The transport unit 30 includes transport roller pairs 34 and 36 that transport the recording medium S fed by the feed roller 32 to the scanning holding unit 40.

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

The image recording unit 50 is provided with a head unit 52. A large number of the head units 52 (for example, black K) have their discharge ports directed toward the recording medium S1, in the direction perpendicular to the paper surface in FIG. In other words, they are arranged in the left-right direction in FIG.
In the drawing, only the black K full line head 52 is shown, but in the case of color, the dedicated full line heads for the colors of yellow Y, magenta M, and cyan C are also conveyed by the black K full line head 52. It is arranged in parallel with the black K full line head 52 upstream or downstream in the direction.
A head driver 54 is connected to each head unit 52 to control the amount of ink discharged from each ink discharge port. The head unit 52 is connected to a supply unit 70 that supplies ink of each color.

  Further, the active energy irradiation unit 56 disposed immediately after the image recording position 42P and downstream of the head unit 52 imparts active energy to the ink in order to immediately cure the ink ejected onto the recording medium S. .

A separation claw 92 is disposed downstream of the position where the recording medium S is separated from the conveyance belt 42 (downstream belt roller 44c position in the figure), and the leading end of the separation claw 92 is near the downstream belt roller 44c and the conveyance belt 42 of the recording medium S. Encourage peeling from
The tray 90 stores the recording media S peeled off from the conveying belt 42 in order.

  Further, in order to suppress the temperature rise in the casing 12 due to the active energy used for ink curing in the active energy irradiation section 56, the exhaust cooling section 80 is disposed at the upper part in the casing 12, and the exhaust cooling section 80 is The internal air is exhausted out of the apparatus.

5A and 5B are schematic diagrams of the configuration of an active energy curable ink jet recording apparatus of a conventional roller-conveying full-line head system, where FIG. 5A is a front view and FIG. 5B is a side view of the full-line head portion. Yes.
In FIG. 5, reference numeral 500 denotes an active energy curable ink jet recording apparatus of a roller transport type, and the same components as those of the active energy curable ink jet recording apparatus of FIG.
In the figure, a platen platen 140 that supports a non-recording surface opposite to the recording surface of the recording medium S is provided, and conveying rollers 136 and 142 are disposed on the front and rear sides of the platen 140, respectively. Each conveying roller rotates in a predetermined direction around the axis center before and after the platen 140, and the recording medium S moves from the conveying roller 136 side to the conveying roller 142 side as each conveying roller 136, 142 rotates. Be transported.
A head unit 52 is disposed above the platen 140, and a plurality of ink discharge portions are arranged at the front end of the head unit 52 in the vertical direction on the paper surface to form a full line head. The tip is directed to the platen 140.
The ink ejected to the recording medium S on the platen 140 is given an active energy such as an electron beam or an ultraviolet ray by the active energy irradiation unit 56 disposed immediately downstream of the head unit 52, and is cured.

  In addition, an exhaust cooling unit 80 is disposed in the upper part of the housing 12 in order to suppress a temperature rise in the housing 12 due to light used for ink curing in the active energy irradiation unit 56, and the exhaust cooling unit 80 is interposed through the exhaust cooling unit 80. The internal air is exhausted outside the equipment.

In such a conventional active energy curable ink jet recording apparatus, if foreign matter such as dust or paper powder enters the apparatus and adheres to the vicinity of the nozzle of the ink jet head, the ink spreads on the nozzle plate. There is a problem that the ink cannot be stably operated because the ink discharge is poor or the ink on the nozzle plate is hardened by the active energy and the head cannot be used.
This is a particularly important problem when the recording medium is large or when the number of nozzles is large, and particularly in a full-line head system in which the maintenance interval is long because head scanning is not performed.
The present invention solves these problems by identifying the causes that cause these problems, prevents foreign matter from entering the apparatus, and does not require short-term maintenance. Therefore, it has excellent productivity and high image quality. An object of the present invention is to provide an active energy curable ink jet apparatus capable of performing drawing.

In order to achieve the above object, an invention according to claim 1 relates to an active energy curable ink jet recording apparatus, wherein an active energy irradiating means and an ink curable by the active energy irradiated by the active energy irradiating means are used as a recording medium. In an inkjet apparatus having an inkjet head that discharges toward the inkjet head and a conveying unit that conveys the recording medium to a position facing the inkjet head, the pressure inside the inkjet apparatus is maintained at a pressure higher than the pressure outside the inkjet apparatus. It is characterized by comprising pressure adjusting means.
According to a second aspect of the present invention, in the active energy curable ink jet apparatus according to the first aspect, the pressure adjusting means increases the pressure in the ink jet apparatus to a higher pressure within a range of 1 Pa to 50 kPa than the pressure outside the ink jet apparatus. It is characterized by maintaining.
According to a third aspect of the present invention, in the active energy curable ink jet apparatus according to the first or second aspect, the pressure adjusting unit generates an air flow in a direction from the ink jet head toward the recording medium. Yes.
According to a fourth aspect of the present invention, in the active energy curable ink jet apparatus according to the third aspect, the pressure adjusting means diverts an airflow directed toward the recording medium in a loading direction and a discharging direction of the recording medium. It is characterized by.

  As described above, according to the present invention, since the pressure inside the active energy curable ink jet apparatus is maintained at a pressure higher than the pressure outside the ink jet apparatus, the airflow always flows from the inside of the apparatus to the outside of the apparatus. Foreign matter from outside the device can not enter the device, so foreign matter such as dust and paper dust will not adhere to the vicinity of the nozzles of the inkjet head, and there will be no short-term maintenance. An active energy curable ink jet apparatus capable of performing the above is obtained.

Embodiments of the present invention will be described below with reference to the drawings.
<Example 1>
FIG. 1 is a schematic configuration diagram of an active energy curable ink jet recording apparatus of a full line head system according to a first embodiment of the present invention of a belt conveyance type, where (a) is a front view and (b) is a side view of a full line head part. Each figure is shown.
In the figure, reference numeral 100 denotes an active energy curable ink jet recording apparatus. In the housing 12 of the active energy curable ink jet recording apparatus 100, a recording medium storage unit 20 that stores a plurality of sheet-like recording media S of the same size and stores the recording medium S from the storage unit 20. Inkjet image on the conveyance unit 30, the scanning conveyance unit 40 that performs scanning while holding the recording medium S carried in by the conveyance unit 30 in the recording position range, and the recording medium S that is held and transferred and scanned by the scanning conveyance unit 40 An image recording unit 50 that performs recording and ultraviolet light irradiation fixing, and a tray 90 to which the recording medium S that has been recorded by the image recording unit 50 is sent out are provided.

  In the recording medium storage unit 20, a storage cassette 22 that stores the recording medium S is detachably disposed below the casing 12 of the active energy curable ink jet recording apparatus 100, and supplies recording media S of different sizes by replacement. Can do. The recording medium storage unit 20 may be configured to mount a plurality of cassettes.

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

The scanning conveyance unit 40 includes a conveyance belt 42 that is stretched and driven by three belt rollers 44a, 44b, and 44c. The conveyance belt 42 is driven from the upstream belt roller 44b toward the downstream belt roller 44c, and the recording medium S is placed and conveyed on the conveyance belt 42 between the upstream belt roller 44b and the downstream belt roller 44c. A number of suction holes for bringing the recording medium S into close contact with the transport belt 42 are provided in the transport belt 42, and the pressure is reduced by a vacuum suction device (not shown).
A substantially intermediate position between the upstream belt roller 44b and the downstream belt roller 44c is set as an image recording position 42P.

The image recording unit 50 is provided with a head unit 52 (for example, black K). A large number of the head units 52 have their discharge ports directed toward the recording medium S1, and are perpendicular to the paper surface in FIG. (That is, in the left-right direction in FIG. 1B). Ink is ejected from the head unit 52 onto a predetermined portion of the recording medium S like an image. In the drawing, only the black K full line head 52 is shown, but in the case of color, the dedicated full line head is similarly transferred for each color of yellow Y, magenta M, and cyan C. The black K full line heads 52 are arranged in parallel with the black K full line head 52 in the vicinity of the upstream or downstream.
A head driver 54 is connected to each head unit 52 to control the amount of ink discharged from each ink discharge port. The head unit 52 is connected to a supply unit 70 that supplies ink of each color.

  Further, immediately after the image recording position 42 </ b> P, an active energy irradiation unit (active energy source such as an ultraviolet ray or an electron beam) 56 is arranged downstream of the head unit 52. The active energy irradiation unit 56 gives the ink active energy such as ultraviolet rays in order to immediately cure the ink ejected on the recording medium S. As a light source that emits active energy, for example, a high-pressure mercury lamp, a metal halide lamp, a black light, a cold cathode tube, an LED (Light Emitting Diode), a laser, an electron gun, or the like can be used.

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 the figure), and the tip of the separation claw 92 contacts the conveyance belt 42 near the downstream belt roller 44c. The separation of the recording medium S from the conveyance belt 42 is urged.
The tray 90 stores the recording media S peeled off from the conveying belt 42 in order. The tray 90 has a leading end side (the conveyance direction side of the recording medium P) located outside the housing 12, a trailing end side 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.

According to the present invention, the above apparatus is characterized in that pressure adjusting means 110 to 130 are provided in place of the exhaust cooling unit 80 provided in FIGS. 4 and 5.
In the figure, 110 is a filter, 120 is a suction fan, and 130 is a duct.
The filter 110 removes dust and foreign matters when the outside air is taken into the apparatus to make clean air. The suction fan 120 introduces clean outside air trapped by the filter 110 into the apparatus. The duct 130 covers the exhaust side of the suction fan 120 on the one hand and extends to the tip while covering the inkjet head 52 on the other side, and opens toward the recording medium S side.

Next, functions of the pressure adjusting means 110 to 130 will be described.
When the suction fan 120 is activated, the outside air including dust is cleaned by the filter 110 and is taken into the apparatus, and the taken-in clean air flows through the duct 130 to the inkjet head 52, and from there to the recording medium S. Then, the air is exhausted toward the recording medium S and is discharged from the outlet of the tray 90 to the outside of the apparatus.
As described above, the pressure adjusting means 110 to 130 always keeps the inside of the ink jet apparatus at a high pressure. This pressure is desirably maintained at a high pressure within a range of 1 Pa to 50 kPa than the pressure outside the ink jet apparatus.
Thus, when the outside air cleaned by the pressure adjusting means 110 to 130 flows around the inkjet head 52 through the duct 130, an air curtain is formed around the inkjet head 52. Even if there is foreign matter such as dust or paper dust, these foreign matter cannot approach the nozzles of the inkjet head, and the inkjet head 52 is kept clean.
Further, when clean air flows along the surface of the recording medium S, dust or the like on the recording medium S is blown off, so that the fixing is performed with the surface of the recording medium S kept clean.
Further, since the inside of the apparatus is always kept at a high pressure, the inside of the apparatus is exhausted from the apparatus through the outlet of the tray 90 to the outside of the apparatus. Since the air sucked into the inside is cleaned by the filter 110, the inside of the apparatus is maintained in a clean state in the final steady state.

  As described above, according to the present invention, the ink jet head is kept clean, the surface of the recording medium S is also cleaned, and foreign matter in the apparatus is discharged outside the apparatus, and clean air is generated in the apparatus. Therefore, there is no short-term maintenance, so that an active energy curable ink jet apparatus that is excellent in productivity and capable of drawing with high image quality can be obtained.

<Example 2>
2A and 2B are schematic diagrams of a configuration of an active energy curable ink jet recording apparatus of a full line head system according to a second embodiment of a roller conveyance type, in which FIG. 2A is a front view, and FIG. 2B is a side view of a full line head portion. Each is shown.
In FIG. 2, reference numeral 200 denotes an active energy curable ink jet recording apparatus of a roller conveyance type, which has a flat platen 140 that supports a non-recording surface opposite to the recording surface of the recording medium S. Conveying rollers 136 and 142 are provided, respectively. Each conveying roller rotates in a predetermined direction around the axis center before and after the platen 140, and the recording medium S moves from the conveying roller 136 side to the conveying roller 142 side as each conveying roller 136, 142 rotates. Be transported.
A head unit 52 is disposed above the platen 140, and a plurality of ink discharge portions are arranged at the front end of the head unit 52 in the vertical direction on the paper surface to form a full line head. The tip is directed to the platen 140. Ink is ejected from the head unit 52 onto a predetermined portion of the recording medium S like an image. In the case of color, similarly for each color of yellow Y, magenta M, and cyan C, the dedicated full line heads are close to each other upstream or downstream in the transport direction of the black K full line head 52, and the black K full Arranged in parallel with the line head 52.
The ink ejected on the recording medium S is given active energy by the active energy irradiation unit 56 disposed immediately downstream of the head unit 52 and is cured.

  According to the present invention, the above apparatus is characterized in that pressure adjusting means 110 to 130 are provided in place of the conventional exhaust cooling unit 80. In the figure, 110 is a filter, 120 is a suction fan, and 130 is a duct. The filter 110 removes dust and foreign matters when the outside air is taken into the apparatus to make clean air. The suction fan 120 introduces clean outside air trapped by the filter 110 into the apparatus. The duct 130 covers the exhaust side of the suction fan 120 on the one hand and extends to the tip while covering the inkjet head 52 on the other side, and opens toward the recording medium S side.

Next, functions of the pressure adjusting means 110 to 130 will be described.
When the suction fan 120 is activated, the outside air including dust is cleaned by the filter 110 and is taken into the apparatus, and the taken-in clean air flows through the duct 130 to the inkjet head 52, and from there to the recording medium S. Then, the air is exhausted toward the recording medium S and is discharged from the outlet of the tray 90 to the outside of the apparatus.
As described above, the pressure adjusting means 110 to 130 always keeps the inside of the ink jet apparatus at a high pressure. This pressure is desirably maintained at a high pressure within a range of 1 Pa to 50 kPa than the pressure outside the ink jet apparatus.
Thus, when the outside air cleaned by the pressure adjusting means 110 to 130 flows around the inkjet head 52 through the duct 130, an air curtain is formed around the inkjet head 52. Even if there is foreign matter such as dust or paper dust, these foreign matter cannot approach the nozzles of the inkjet head, and the inkjet head 52 is kept clean.
Further, when clean air flows along the surface of the recording medium S, dust or the like on the recording medium S is blown off, so that the fixing is performed with the surface of the recording medium S kept clean.
Further, since the inside of the apparatus is always kept at a high pressure, the inside of the apparatus is exhausted from the apparatus through the outlet of the tray 90 to the outside of the apparatus. Since the air sucked into the inside is cleaned by the filter 110, the inside of the apparatus is maintained in a clean state in the final steady state.

  As described above, according to the present invention, the ink jet head is kept clean, the surface of the recording medium S is also cleaned, and foreign matter in the apparatus is discharged outside the apparatus, and clean air is generated in the apparatus. Therefore, there is no short-term maintenance, so that an active energy curable ink jet apparatus that is excellent in productivity and capable of drawing with high image quality can be obtained.

<Example 3>
1 and 2 show an active energy curable ink jet recording apparatus of a type in which the recording medium S is stored in the storage cassette 22 of the recording medium storage unit 20 and the recording medium S is transported therefrom. 3 is applied to an active energy curable ink jet recording apparatus in which a recording medium S is inserted from a manual feed port. Accordingly, the apparatus has an inlet in addition to the recording medium outlet (tray 90) in the apparatus, which is different from FIGS.
FIG. 3 shows an active energy curable ink jet recording apparatus according to Embodiment 3 of the present invention.
In the figure, 300 is an active energy curable ink jet recording apparatus according to Example 3, 110 is a filter, 120 is a suction fan, 130 is a duct, and 30a is a recording medium manual feed port.
In this apparatus, since there is a manual feed port for the recording medium S in addition to the outlet for the recording medium S, the flow of the air flowing to the ink jet head 52 is divided into the downstream side W2 and the upstream side W3. While removing dust and the like on S, the air is exhausted from the outlet and the inlet to the outside of the apparatus.

The inside of the ink jet apparatus is always kept at a high pressure by the pressure adjusting means 110 to 130, and the pressure is desirably kept at a high pressure within a range of 1 Pa to 50 kPa than the pressure outside the ink jet apparatus.
Thus, when the outside air cleaned by the pressure adjusting means 110 to 130 flows around the inkjet head 52 through the duct 130, an air curtain is formed around the inkjet head 52. Even if there is foreign matter such as dust or paper dust, these foreign matter cannot approach the nozzles of the inkjet head, and the inkjet head 52 is kept clean.
Furthermore, since clean air flows in both the upstream and downstream directions along the surface of the recording medium S, ink landing is performed in a state where dust or the like on the recording medium S is blown away and the surface of the recording medium S is kept clean. And ink fixing is performed.
Further, since the inside of the apparatus is always kept at a high pressure, the inside of the apparatus is exhausted from the apparatus through the outlet of the tray 90 to the outside of the apparatus. Since the air sucked into the inside is cleaned by the filter 110, the inside of the apparatus is maintained in a clean state in the final steady state.

  As described above, according to the present invention, the ink jet head is kept clean, the surface of the recording medium S is also cleaned, and foreign matter in the apparatus is discharged outside the apparatus, and clean air is generated in the apparatus. Therefore, there is no short-term maintenance, so that an active energy curable ink jet apparatus that is excellent in productivity and capable of drawing with high image quality can be obtained.

  In the first to third embodiments, a full line head is used as an ink jet, but the present invention can be effectively applied to a serial scan head.

  In the above example, a system in which a full line head is applied as a head has been described. However, the present invention can be effectively applied even in a system using a serial scan head.

  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-type ink composition contains (a) a cationic polymerizable compound and (b) a compound that generates an acid upon irradiation with 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 and cures by an acid generated from a compound that generates an acid upon irradiation with light energy, which will be described later. Various known cationic polymerizable monomers known as photo cationic polymerizable monomers can be used. Examples of the cationic polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  The surface tension of the ink composition of the present invention is preferably 20 to 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 compounds having addition-polymerizable ethylenically unsaturated bonds that can be used in the ink composition of the present invention include unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid Etc.) and an aliphatic polyhydric alcohol compound, an amide of the unsaturated carboxylic acid and an aliphatic polyamine compound, and the like.

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

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

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate. Furthermore, the mixture of the above-mentioned ester monomer can also be mention | raise | lifted. Specific examples of 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.

As another example, a vinyl compound containing a hydroxyl group represented by the following general formula (A) is added to a polyisocyanate compound having two or more isocyanate groups per molecule described in JP-B-48-41708. Examples thereof include vinyl urethane compounds containing two or more polymerizable vinyl groups in one molecule to which a monomer is added. CH ₂ = C (R) COOCH ₂ CH (R ′) OH (A) (where R and R ′ represent H or CH ₃ )
Further, as described in JP-A-51-37193, urethane acrylates, JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, etc. Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid can be used. Furthermore, Journal of Japan Adhesion Association vol.20, No. 7, pages 300 to 308 (1984) as photocurable monomers and oligomers can also be used. In the present invention, these monomers may be used in a chemical form such as a prepolymer, that is, a dimer, a trimer and an oligomer, or a mixture thereof and a copolymer thereof.

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

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

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

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

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

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

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

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

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

[Others]
In addition, known compounds can be used as necessary. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins. Resin, rubber resin, wax and the like can be appropriately selected and used. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to 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 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 glycol and polyol acrylate (e.g. propoxylated neopentyl glycol Diacrylate, ethoxylated trimethylol proppant Acrylate), and mixtures thereof.
Examples of acrylate oligomers include ethoxylated polyethylene glycol, ethoxylated trimethylolpropane acrylate and polyether acrylate and ethoxylates thereof, and urethane acrylate oligomers.
Examples of methacrylates include hexanediol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and mixtures thereof.
The amount of oligomer added is preferably 1 to 80% by weight, more preferably 1 to 10% by weight, based on the total weight of the ink composition.

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

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

  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 above-mentioned coloring material. In particular, if it is prepared so as to have ink jet recording characteristics, a clear ink for water-based photocurable ink jet recording can be obtained. If such an ink is used, a clear film can be obtained because it does not contain a color material. Clear inks that do not contain color materials can be used for undercoats to give recording materials suitable for image printing, or for surface protection of images formed with ordinary inks, further decoration and gloss The use etc. for the overcoat for the purpose of provision etc. are mentioned. In the clear ink, colorless pigments or fine particles that are not intended for coloring can be dispersed and contained according to these applications. By adding these, it is possible to improve various properties such as image quality, fastness, and workability (handling property) of the printed matter in both the undercoat and the overcoat.

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

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

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

1 is a schematic configuration diagram of an active energy curable ink jet recording apparatus of a full line head system according to a first embodiment of a belt conveyance type of the present invention. FIG. 5 is a schematic configuration diagram of an active energy curable ink jet recording apparatus of a full line head system according to a second embodiment of the roller conveyance type of the present invention. It is the structure schematic of the active energy curable inkjet recording device which concerns on Example 3 of this invention. 1 is a schematic configuration diagram of an active energy curable ink jet recording apparatus of a conventional full line head system of a belt conveyance type. It is the structure schematic of the active energy hardening type inkjet recording device of the conventional full line head system of a roller conveyance type.

Explanation of symbols

100, 200, 300 Active energy curable ink jet recording apparatus 12 according to the present invention 12 Case 20 Recording medium storage unit 22 Storage cassette 30 Transport unit 30a Recording medium manual feed port 32 Feed rollers 34, 36 Transport roller pair 40 Scan transport unit 44a, 44b, 44c Belt roller 42 Conveying belt 42P Image recording position 50 Image recording unit 52 Head unit 54 Head driver 70 Ink supply unit 56 Active energy irradiation unit 80 Exhaust cooling unit 90 Tray 92 Peeling claw S Recording medium

Claims (4)

  Active energy irradiating means, an inkjet head that ejects ink curable by active energy irradiated by the active energy irradiating means toward a recording medium, and conveying means that conveys the recording medium to a position facing the inkjet head An active energy curable ink jet apparatus comprising pressure adjusting means for maintaining the pressure inside the ink jet apparatus at a pressure higher than the pressure outside the ink jet apparatus.   2. The active energy curable ink jet apparatus according to claim 1, wherein the pressure adjusting means maintains the pressure inside the ink jet apparatus at a high pressure within a range of 1 Pa to 50 kPa than the pressure outside the ink jet apparatus.   The active energy curable ink jet apparatus according to claim 1, wherein the pressure adjusting unit generates an air flow in a direction from the ink jet head toward the recording medium.   4. The active energy curable ink jet apparatus according to claim 3, wherein the pressure adjusting means diverts an airflow directed toward the recording medium in a loading direction and a discharging direction of the recording medium.

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