JP2008296419A - Ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recorder superior in binding durability in a line head recording method. <P>SOLUTION: The ink jet recorder includes a line type ink jet recorder composed of a plurality of nozzles arranged for discharging an ink cured by irradiation of an active energy ray on a recording medium, a conveyance means for conveying the recording medium in the same direction as the arranged direction of the plurality of nozzles, and an irradiation means for irradiating the active energy ray on the ink landed on the recording medium. In the ink jet recorder, recording on the recording medium is performed a plurality of times by the same color ink, at least one irradiation of the active energy ray is performed during the plurality of times of recording, and irradiation of the active energy ray is performed after the last recording. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus using ink that is cured by irradiation with active energy rays.

  The ink jet recording apparatus is a relatively simple apparatus that can record high-definition images and has been rapidly developed in various fields. In addition, there are various uses of the ink jet recording method, and a recording medium or ink jet ink suitable for each purpose is used.

  In particular, in recent years, high speed and high image quality of the ink jet recording system have attracted much attention, and the recording width of the head has been increased from the viewpoint of increasing the number of nozzles of the ink jet recording head. Such an ink jet recording head is referred to as a line head (see Patent Document 1). By adopting such a line head type ink jet recording head, the recording speed has been greatly improved, and an ink jet recording apparatus having performance capable of withstanding light printing applications has also been developed. However, with normal water-based inkjet ink, printing paper with low ink absorption such as art paper and coated paper, which is mainly used as recording paper for offset printing and gravure printing, plastic film with no ink absorption, etc. In recording, there is a problem such as so-called color bleeding in which ink liquids having different hues are mixed on a recording medium and cause color turbidity.

  In response to the above problems, a hot-melt ink composition made of a solid wax or the like at room temperature is used. It is liquefied by heating, sprayed with some energy applied, and deposited on the recording medium, and at the same time cooled and solidified. A hot melt ink jet recording apparatus that records dots has been proposed (see Patent Documents 2 and 3). Since this hot melt ink is solid at room temperature, it does not get dirty during handling, and since it does not substantially evaporate ink when melted, it does not cause nozzle clogging. Furthermore, it is said to be an ink composition that solidifies immediately after adhering, has little color bleeding, and provides good print quality regardless of paper quality. However, an image recorded by such a method has problems such as deterioration in quality due to the rising of the dots and insufficient abrasion resistance because the ink dots are in the form of soft wax.

  On the other hand, an inkjet recording ink that is cured by irradiation with active energy rays has been disclosed (see Patent Document 4). In addition, a so-called non-aqueous ink containing a pigment as a colorant, a triacrylate or higher polyacrylate as a polymerizable material, and a ketone or alcohol as a main solvent has been proposed (see Patent Document 5). . An aqueous active energy ray-curable ink jet recording ink composition containing a polyurethane compound, a basic compound, a colorant, a water-soluble organic solvent and water containing a group having an active energy ray-curable unsaturated double bond Has been proposed (see Patent Document 6). Furthermore, a water-based inkjet ink comprising a self-dispersing pigment having one or more hydrophilic groups bonded to the surface of pigment particles, an ultraviolet curable monomer made of a vinyl compound, a photopolymerization initiator, and water. It has been proposed (see Patent Document 7).

However, when an inkjet ink containing a photocurable resin is recorded by the line head method, the ink droplets of adjacent dots land before the ink droplets ejected from the inkjet head are fixed by light irradiation. In the secondary color, tertiary color, and other regions where the ink droplets of each other are close to each other and have a large amount of shot, there is a new problem that banding occurs in a solid image of the same color.
JP-A-6-183029 U.S. Pat. No. 4,390,369 U.S. Pat. No. 4,484,948 U.S. Pat. No. 4,228,438 Japanese Patent Publication No. 5-64667 JP 2002-80767 A JP 2002-275404 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording apparatus having excellent banding resistance in a line head recording system using ink that is cured by irradiation with active energy rays.

The above object of the present invention is achieved by the following configurations.
1.
A line-type inkjet recording head in which a plurality of nozzles that discharge ink that is cured by irradiation of active energy rays to a recording medium are arranged;
Conveying means for conveying the recording medium in a direction perpendicular to the direction in which the plurality of nozzles are arranged;
Irradiating means for irradiating the ink landed on the recording medium with active energy rays,
Recording on the recording medium with the same color ink is performed in a plurality of times, and at least one active energy ray is irradiated during the plurality of times of recording, and the active energy rays are irradiated after the final recording. An ink jet recording apparatus.
2.
2. The ink jet recording apparatus according to item 1, wherein the resolution (dpi) of dots in the transport direction of the recording medium per recording is changed by changing the transport speed of the recording medium.
Here, dpi represents the number of dots per inch = 2.54 cm.
3.
By increasing the conveyance speed of the recording medium N times (N is an integer of 2 or more), the resolution (dpi) of dots in the conveyance direction of the recording medium per recording is 1 / N. 3. The inkjet recording apparatus according to 1 or 2 above.
4).
4. The recording apparatus according to any one of the above items 1 to 3, wherein dots are thinned out from a 2 × 2 dot matrix of the same color ink so as to be arranged obliquely, and recording is performed once with the same color ink. Inkjet recording apparatus.
5.
The ink of the same color is at least one type constituting an ink jet ink set comprising three or more types of inks having different hues;
Of the two ink combinations selected from the three or more inks, a combination of two inks having the worst bleeding is set in advance.
The above-mentioned items 1 to 3 are characterized in that the two kinds of ink dots having the worst bleeding are thinned out from a 2 × 2 dot matrix of various inks so as to be diagonally arranged, and recording is performed once with various inks. The inkjet recording apparatus of any one.
6).
6. The ink jet recording apparatus according to any one of 1 to 5, wherein the active energy ray is ultraviolet light.
7).
The ink jet recording apparatus according to any one of 1 to 6, wherein the conveying means is a belt.
8).
7. The ink jet recording apparatus according to any one of 1 to 6, wherein the conveying unit is a drum.
9.
The ink jet recording according to any one of 1 to 8, wherein the recording medium is reciprocated with respect to the line type ink jet recording head, and recording is performed by each of forward and backward movements of the recording medium. apparatus.
10.
10. The ink jet recording apparatus according to any one of 1 to 9, wherein the recording medium is a sheet.
11.
10. The ink jet recording apparatus according to any one of 1 to 9, wherein the recording medium is roll paper.

  According to the present invention, it is possible to provide an ink jet recording apparatus having excellent banding resistance in a line head recording method using ink that is cured by irradiation with active energy rays.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  The present invention relates to a line-type ink jet recording head in which a plurality of nozzles for discharging ink that is cured by irradiation of active energy rays to a recording medium, and a direction orthogonal to the direction in which the plurality of nozzles are arranged. , Having a conveying means for conveying the recording medium and an irradiating means for irradiating the ink landed on the recording medium with an active energy ray, and performing recording on the recording medium with the same color ink in a plurality of times, In addition, at least one active energy ray is irradiated during a plurality of times of recording, and the active energy rays are irradiated after the last recording, and the ink is cured by the irradiation of the active energy rays. Achieving an inkjet recording device with excellent banding resistance in the line head recording system using ink Heading, it is up which led to the present invention.

  When image recording is performed using an ink jet recording head of a line head type ink that is cured by irradiation with active energy rays, an image with a large amount of shot is recorded, particularly in a solid image portion recorded using the same color ink. The present inventors have found a problem that a so-called banding phenomenon is likely to occur, in which a stripe pattern is generated perpendicularly or parallel to the recording direction.

  As a result of diligent investigations on this problem, the present inventors have found that, after the first dot of the same color inkjet ink has landed on the recording medium, the second dot is positioned adjacent to the first dot. It has been found that banding is drastically eliminated by adopting an ink jet recording apparatus that performs irradiation of active energy rays at least once before the landing.

  The reason for this is not clear, but by irradiating light before adjacent dots of the same color land, the dots are sufficiently fixed on the recording medium or on the ink droplets that have already been ejected. It is presumed that the occurrence of the misalignment between the ink liquids between the two is suppressed and the banding is improved. Furthermore, even if the conditions such as the time from landing to irradiation and the time from landing to adjacent dots are the same, the color bleed between the same colors on the recording medium rather than the color bleed caused by the mixing of ink liquids of different colors on the recording medium. It has been found that the banding phenomenon caused by the mixing of the ink liquids has a more severe influence when the recorded inkjet recording image is visually observed. Compared to the method in which the same color ink is ejected at a short time interval of several hundred μsec or less and the active energy ray is finally irradiated, the same color ink is divided into a plurality of times, ink landing and light irradiation, and the adjacent dot landing. By irradiating the active energy ray at least once in a time interval of several hundred msec to several seconds, it has been possible to realize both good bleed resistance and banding resistance.

  In the present invention, the adjacent dots are defined as two dots that are in contact with the transport direction, two dots that are in contact with the transport direction perpendicularly, or four dots that combine them.

  The ink jet ink applied to the ink jet recording apparatus of the present invention preferably contains a photoreactive resin that is cured or cross-linked by irradiation with water and active energy rays. This is because the water-based ultraviolet curable ink-jet ink has a low viscosity, and therefore it takes a very short time to cause the ink liquid to shift between dots of the same color.

  As a photoreactive resin, a polymer compound having a plurality of side chains with respect to the hydrophilic main chain and capable of crosslinking between side chains by irradiation with active energy rays (hereinafter referred to as high active energy ray crosslinkability). This effect is noticeable even in a region where the amount of implantation is larger. The reason for this is that the ink containing the active energy ray-crosslinkable polymer has a very high viscosity increase rate with respect to light irradiation, so that it can be firmly fixed on the recording medium by the arrival of adjacent dots of the same color. It is estimated that this is possible. Further, by heating the back surface of the recording medium, leveling between dots is improved and glossiness is improved.

  Details of the present invention will be described below.

<Inkjet recording device>
FIG. 1 is a schematic top view showing an example of an ink jet recording apparatus in which an ink jet recording head unit including a plurality of ink jet recording heads as a comparative example and a light irradiation device are arranged.

  FIG. 1 shows an ink set composed of two or more inks on the platen 2 holding the recording medium P (in FIG. 1, an example of an ink set composed of yellow ink, magenta ink, cyan ink, and black ink). An ink jet recording head unit HU composed of a line head type ink jet recording head HY, HM, HC, HK, and a light irradiation device 5 on the downstream side (downstream in the transport direction). Inkjet recording apparatus 1. The ink set may be an ink set composed of two or more kinds of inks or may be a single color ink.

  Next, the recording order (landing order) of each ink using the inkjet recording apparatus 1 having the configuration shown in FIG. 1 will be described with reference to FIG. FIG. 2 shows dots of 3 × 3 = 9 pixels, but in this embodiment, the recording is performed a plurality of times (hereinafter, the times may be referred to as passes), and is composed of dots 1 to 4. An example of completing the recording of the unit area will be described.

  When recording on the recording medium in one pass using the inkjet recording apparatus 1 shown in FIG. 1, the landing order of the dots D of the respective color inks on the recording medium is basically shown in FIG. The indicated dot 1, dot 3, dot 2, and dot 4 are ejected to the recording medium almost simultaneously. The landing time difference between the dots 1 and 2 and the landing time difference between the dots 3 and 4 for the same color ink are determined by the resolution of the image in the conveyance direction of the recording medium and the conveyance speed of the recording medium. For example, when it is assumed that the conveyance speed is 350 mm / sec, the landing time difference between the dots 1 and 2 and the landing time difference between the dots 3 and 4 are approximately several tens of microseconds, although they differ depending on the resolution of the image. 100 μsec.

  FIG. 3 is a schematic top view showing an example of an ink jet recording apparatus in which a plurality of ink jet recording head units of the present invention and a plurality of light irradiation devices are arranged.

  The ink jet recording apparatus 1 shown in FIG. 3 has two ink jet recording head units HU1 and HU2 each composed of a plurality of ink jet recording heads corresponding to ink sets on a platen 2 holding a recording medium P. The light irradiation device 5 is disposed at a corresponding position on the downstream side (downstream in the transport direction) of each of the inkjet recording head units HU1 and HU2. The inkjet recording head unit HU1 and the inkjet recording head unit HU2 preferably have the same resolution, and the nozzle positions of the inkjet recording head unit HU1 and the inkjet recording head unit HU2 are arranged so as to be equal to each other in the vertical direction of the transport direction. It is preferable. After each ink is ejected from each ink jet recording head HK1, HC1, HM1, HY1 constituting the ink jet recording head unit HU1, each ink landed from the light irradiation device 5 arranged on the downstream side (downstream in the transport direction) After irradiating the droplets with active energy rays, and then ejecting ink from each of the inkjet recording heads HK2, HC2, HM2, and HY2 constituting the inkjet recording head unit HU2, the droplets are disposed downstream (downstream in the transport direction). Each of the landed ink droplets is irradiated with active energy rays from the light irradiation device 5. Ink set 1 (installed in HU1) and inkjet set 2 (installed in HU2) to be loaded in each inkjet recording head may be an ink set composed of two or more types of inks or may be a single color ink. However, the ink set 1 and the ink set 2 preferably have the same color ink. The same color ink is ink containing the same kind of color material.

  In addition, a recording operation for ejecting ink from each ink jet recording head, an operation for transporting a recording medium by transporting means (see FIGS. 18 to 20), and irradiating each ink droplet landed from the light irradiation device 5 with active energy rays The operation | movement to perform is performed based on control from the control part 3 (refer FIGS. 18-20).

  Next, the recording order (landing order) of each ink using the inkjet recording apparatus 1 having the configuration shown in FIG. 3 will be described with reference to FIG.

  As a first method for landing ink droplets on a recording medium, first, the ink 1 is made to land on the dots 1 and 4 shown in FIG. After irradiating the droplets with active energy rays and curing them, the inkjet recording head unit HU2 causes the dots 2 and 3 shown in FIG. 2 to land, and then the light irradiation device 5 activates each landed ink droplet. This is a method of curing by irradiating energy rays.

  FIG. 6 shows an ink landing state in each pass when such a recording method is used for an image obtained by solidifying Y, M, C, and K at 100%. FIG. 6 shows how recording is performed in each pass using a thinning pattern in which Y, M, C, and K are equal, from the first pass to the second pass, together with the landing order of each pixel. The four colors are arranged with respect to the paper surface in the order shown in the drawing, and are recorded in the landing order according to the conveyance direction (see FIG. 2) of the recording medium indicated by the arrow for each pass.

  In FIG. 6, dots are thinned out from a 2 × 2 dot matrix of the same color ink so as to be arranged diagonally, and printing is performed once with the same color ink, whereby dots are arranged in a checkerboard pattern during one-pass recording. . This increases the distance between dots during one-pass printing, makes it difficult for bleeding to occur, and makes it possible to irradiate light once before landing of adjacent dots of the same color ink. The banding of the solid image in the portion where there is a lot of is good.

  By taking such a landing order, for example, when the transport speed is 350 mm / sec, the dot 1 and the dot for the same color ink differ depending on the distance between the two inkjet recording heads that eject the same color ink. It is possible to adjust the landing time difference of 2 and the landing time differences of the dots 3 and 4 to several hundred msec. The resolution of the image obtained by this method is equal to the resolution of the inkjet recording head unit HU1 and the inkjet recording head unit HU2. As a result, it is possible to irradiate light once until the adjacent dot landing of the same color ink by the inkjet recording head unit HU2, and the banding resistance of the solid image in the portion where the amount of shots such as the secondary color is large is improved.

  Further, in the example of this hitting method, it is preferable to double the recording medium conveyance speed as compared with the ink jet recording apparatus of FIG.

  By changing the conveyance speed of the recording medium, the resolution (dpi) of dots in the conveyance direction of the recording medium per recording is changed. Specifically, the resolution (dpi) of dots in the recording medium conveyance direction per recording is set to 1 / N by increasing the recording medium conveyance speed N times (N is an integer of 2 or more). Thus, when there are a plurality of recording modes having different dot resolutions (dpi) in the conveyance direction of the recording medium per recording, the dot resolution (dpi) in the conveyance direction without changing the drive frequency of the inkjet recording head. ) Can be changed, so that more stable ink discharge is possible.

  In the above first method, the case where the dot thinning pattern is the same among the four color ink jet recording heads constituting one ink jet recording head unit HU has been described.

  On the other hand, as a second method for landing ink droplets on a recording medium, a case will be described in which the dot thinning pattern is made different between different color ink jet recording heads constituting one ink jet recording head unit HU.

  Here, since four colors of ink are recorded in two passes, at least two of these ink droplets must land on the same pixel in the same pass. In such a case, as shown below, grouping may be performed such that different thinning patterns are used for two colors that are particularly prone to bleeding.

  First, dots 1 and 4 shown in FIG. 2 are recorded by the inkjet recording heads HY1 and HC1 of the inkjet recording head unit HU1, and dots 2 and 3 shown in FIG. 2 are recorded by the inkjet recording heads HM1 and HK1. After irradiating and curing each of the landed ink droplets with active energy rays from the light irradiation device 5, the dots 2 and 3 shown in FIG. 2 are formed by the inkjet recording heads HY2 and HC2 of the inkjet recording head unit HU2. This is a method of recording, recording the dots 1 and 4 shown in FIG. 2 by the ink jet recording heads HM2 and HK2, and then irradiating each of the landed ink droplets with active energy rays and curing them. .

  FIG. 7 shows an ink landing state in each pass when such a recording method is used for an image obtained by solidifying Y, M, C, and K at 100%. FIG. 7 uses a thinning pattern in which C and Y are equal, K and M use a pattern complementary to this, and the state of recording while exchanging these in each pass from the first pass to the second pass. Up to the eye is shown together with the landing order of each pixel. The four colors are arranged with respect to the paper surface in the order shown in the figure, and are recorded in the landing order according to the conveyance direction of the recording medium indicated by the arrow for each pass.

  This method is characterized in that the ink amount of dots during one-pass printing is small. As a result, the dot diameter is reduced and bleeding is less likely to occur, and it is possible to irradiate light once before the adjacent dots land with the same color ink. Banding is good. In this example, a thinning pattern in which C and Y are equal is used, and K and M use a complementary pattern, and recording is performed while exchanging them in each pass. Therefore, M and K for Y and C are recorded. It is effective when applied when bleeding is likely to occur.

  By taking such a landing order, for example, when the transport speed is 350 mm / sec, it differs depending on the distance between two inkjet recording heads that eject the same color ink, but the same color dot 1 and dot 2 , And the landing time difference between the dots 3 and 4 of the same color can be adjusted to several hundred msec. The resolution of the image obtained by this method is equal to the resolution of the inkjet recording head units HU1 and HU2, and as a result, it is possible to irradiate light once before the adjacent dots of the same color ink land, and inkjet recording. Since the maximum ink shot amount of the image recorded by the head unit HU1 can be reduced, the banding resistance of the solid image is improved in a portion where the shot amount of the secondary color or the like is large.

  FIG. 8 is a modified example of FIG. 7, and uses a thinning pattern in which C and K are equal, and Y and M use a complementary pattern, and recording is performed while exchanging these in each pass. It is effective when applied when bleeding of Y and M with respect to C and K is likely to occur.

  FIG. 9 is a modified example of FIG. 7, and uses a thinning pattern in which Y and K are equal, and C and M use a complementary pattern, and recording is performed while exchanging these patterns in each pass. It is effective when applied when C and M bleeding with respect to Y and K is likely to occur.

  FIG. 10 is a modified example of FIG. 7, where Y uses a predetermined thinning pattern, K, M, and C use a complementary pattern, and recording is performed while exchanging these in each pass. . It is effective when applied when bleeding of K, C, and M with respect to Y is likely to occur.

  FIG. 11 is a modification of FIG. 7, where M uses a predetermined thinning pattern, K, Y, and C use a complementary pattern, and recording is performed while exchanging these in each pass. . It is effective when applied when bleeding of K, C, and Y with respect to M is likely to occur.

  FIG. 12 is a modified example of FIG. 7, in which C uses a predetermined thinning pattern, K, Y, and M use a complementary pattern, and recording is performed while exchanging these in each pass. . It is effective when applied when bleeding of K, Y, and M with respect to C is likely to occur.

  FIG. 13 is a modification of FIG. 7, where K uses a predetermined thinning pattern, M, Y, and C use a complementary pattern, and recording is performed while exchanging these in each pass. . It is effective when applied when bleeding of Y, C, and M with respect to K is likely to occur.

  FIG. 4 is a schematic top view illustrating an example of an ink jet recording apparatus in which a plurality of ink jet recording heads and a plurality of light irradiation apparatuses, which are comparative examples, are alternately arranged.

  In the ink jet recording apparatus 1 shown in FIG. 4, the ink jet recording heads HK, HC, HM, and HY are sequentially arranged on the platen 2 that holds the recording medium P in the transport direction, and further downstream of each ink jet recording head ( In this configuration, a pair of light irradiation devices 5 are arranged on the downstream side in the transport direction. The respective ink jet recording heads HK, HC, HM, and HY have the same resolution, and are preferably adjusted so that the nozzle positions of the respective ink jet recording heads are equal to the vertical direction of the transport direction.

  Next, the recording order (landing order) of each ink using the ink jet recording apparatus having the configuration shown in FIG. 4 will be described with reference to FIG.

  In the ink jet recording apparatus 1 having the configuration shown in FIG. 4, the dots 1 to 4 shown in FIG. 2 are simultaneously discharged onto the recording medium from the nozzles of the respective ink jet recording heads. Therefore, the landing time difference between the dots 1 and 2 of the same color and the landing time difference between the dots 3 and 4 of the same color are determined by the resolution of the image in the conveyance direction of the recording medium and the conveyance speed of the recording medium. When the speed is 350 mm / sec, the landing time difference between the dots 1 and 2 and the landing time difference between the dots 3 and 4 differ from several tens of microseconds to several hundreds of microseconds. It becomes.

  FIG. 5 is a schematic top view showing an example of an ink jet recording apparatus in which a plurality of ink jet recording head units and a plurality of light irradiation apparatuses according to the present invention are alternately arranged.

  An ink jet recording apparatus 1 shown in FIG. 5 includes an ink jet recording head unit HU1, ink jet recording heads HK2, HC2, and HM2, which are composed of ink jet recording heads HK1, HC1, HM1, and HY1 on a platen 2 that holds a recording medium P. And HY2, an inkjet recording head unit HU2, an inkjet recording head HK3, HC3, HM3 and HY3, an inkjet recording head unit HU3, and an inkjet recording head HK4, HC4, HM4 and HY4. Units HU4 are sequentially arranged in the conveyance direction of the recording medium, and a pair of light irradiation devices 5 are arranged on the downstream side (downstream side in the conveyance direction) of each inkjet recording head unit. A. The inkjet recording heads constituting the inkjet recording head units HU1 to HU4 have the same resolution. The inkjet recording head unit HU1 and the inkjet recording head unit HU4, and the inkjet recording head unit HU2 and the inkjet recording head unit HU3 are arranged so that the nozzle positions are equal in the vertical direction of the transport direction. Furthermore, as shown in FIG. 21, it is preferable that the nozzle pitches of the inkjet recording head unit HU1 and the inkjet recording head unit HU2 are shifted by a half pitch in the direction perpendicular to the transport direction.

  FIG. 21 is a bottom view showing a relationship of nozzle positions between the inkjet recording head units.

  FIG. 21 shows the arrangement of the nozzles N as viewed from the bottom side with respect to the inkjet recording head unit HU1 and the inkjet recording head unit HU2. For example, when the resolution of each inkjet recording head is x (dpi) The nozzle position interval in each inkjet recording head is 25.4 / x (mm), and the nozzle positions of each inkjet recording head constituting the inkjet recording head unit HU1 and the inkjet recording head unit HU2 are half pitch, that is, 12.2. It is preferable to adopt a configuration in which the position is shifted by 7 / x (mm).

  In the first recording method using the ink jet recording apparatus 1 shown in FIG. 5, first, ink is ejected by the ink jet recording head unit HU1, the curing process is performed by the light irradiation device 5, and then the ink jet recording head unit HU2 is used. The ink is ejected by the light irradiation device 5, the curing process is performed by the light irradiation device 5, the ink is ejected by the ink jet recording head unit HU3, the curing process is performed by the light irradiation device 5, and finally the ink is ejected by the ink jet recording head unit HU4. It discharges and performs a hardening process with the light irradiation apparatus 5, and records an image. The ink jet set loaded in each ink jet recording head unit may be an ink set composed of two or more kinds of inks or may be a single color ink, but the ink jet set loaded in each ink jet recording head unit is It is preferable to have inks of the same color.

  Next, the recording order (landing order) of each ink using the ink jet recording apparatus 1 having the configuration shown in FIG. 5 will be described with reference to FIG. It is not limited to the landing order.

  First, the dot 1 shown in FIG. 2 was recorded from the ink jet recording head unit HU1 and irradiated with active energy rays, and then the dot 4 shown in FIG. 2 was recorded from the ink jet recording head unit HU2 and irradiated with active energy rays. Thereafter, the dots 3 shown in FIG. 2 are recorded from the ink jet recording head unit HU3 and irradiated with active energy rays, and finally, the dots 2 shown in FIG. 2 are recorded from the ink jet recording head unit HU4. , And image recording is completed.

  FIG. 14 shows an ink landing state in each pass when such a recording method is used for an image obtained by solidifying Y, M, C, and K at 100%. FIG. 14 shows how recording is performed in each pass using a thinning pattern in which Y, M, C, and K are equal, from the first pass to the fourth pass, together with the landing order of each pixel. The four colors are arranged with respect to the paper surface in the order shown in the figure, and are recorded in the landing order according to the conveyance direction of the recording medium indicated by the arrow for each pass.

  FIG. 14 is characterized in that the dots are arranged not to be continuous in any of the transport direction, the nozzle arrangement direction, and the oblique direction during one pass printing. This increases the distance between dots during one-pass printing, makes it difficult for bleeding to occur, and makes it possible to irradiate light once before landing of adjacent dots of the same color ink. The banding of the solid image in the portion where there is a lot of is good. Compared with the configuration of FIG. 3, since the distance between dots at the time of one-pass printing becomes longer, the effect of suppressing bleeding is high.

  In image recording using the inkjet recording apparatus 1 shown in FIG. 5, for example, when the transport speed is 350 mm / sec, the color of the same color varies depending on the distance between any two inkjet recording heads that eject the same color ink. With respect to all combinations of two arbitrary dots selected from four dots 1 to 4, the landing time difference can be adjusted to several hundred msec, and at least one light irradiation can be performed during this time. The resolution of the image obtained by this method is twice that of the inkjet recording head unit HU1, and the maximum ink ejection amount of the image recorded by the inkjet recording head unit HU1 can be reduced. Banding resistance of a solid image in a portion with a large amount becomes good.

  In the example of this hitting method, it is preferable to double the recording medium conveyance speed as compared with the ink jet recording apparatus of FIG.

  In the above first method, the case where the dot thinning pattern is the same among the four color ink jet recording heads constituting one ink jet recording head unit HU has been described.

  On the other hand, as a second method for landing ink droplets on a recording medium, a case will be described in which the dot thinning pattern is made different between different color ink jet recording heads constituting one ink jet recording head unit HU.

  Here, since four colors of ink are recorded in four passes, it becomes possible for the four colors of ink to land on different pixels in the same pass. That is, these four color ink droplets are not simultaneously recorded at the same landing point in the same pass. In such a case, as shown below, particularly in one-pass printing, grouping is performed such that a pattern in which two colors that are likely to cause bleeding are arranged diagonally among adjacent 2 × 2 = 4 dots is used. Just do it.

  Specifically, among the combinations of the two colors selected from the four colors of ink, the combination of the two colors having the worst bleeding is experimentally obtained and set in advance. What is necessary is just to perform recording once with the four color inks by thinning out the dots of the two color inks having the worst bleeding from the 2 × 2 dot matrix of the four color inks so as to be arranged obliquely.

  First, the dot 1 shown in FIG. 2 is recorded by the ink jet recording head HY1 of the ink jet recording head unit HU1, the dot 2 shown in FIG. 2 is recorded by the ink jet recording head HM1, and the ink jet recording head HC1 shown in FIG. The dots 3 are recorded, the dots 4 shown in FIG. 2 are recorded by the ink jet recording head HK1, and each of the landed ink droplets is once irradiated with an active energy ray and cured by the light irradiation device 5, and then the ink jet recording is performed. 2 is recorded by the ink jet recording head HY2 of the head unit HU2, the dot 3 shown in FIG. 2 is recorded by the ink jet recording head HM2, and the dot 2 shown in FIG. 2 is recorded by the ink jet recording head HC2. Ink jet recording head HK2 2, after recording the dots 1 shown in FIG. 2 and irradiating the ink droplets that have landed once with active energy rays and curing them, the ink jet recording head HY3 of the ink jet recording head unit HU3 2 is recorded, the dot 1 shown in FIG. 2 is recorded by the ink jet recording head HM3, the dot 4 shown in FIG. 2 is recorded by the ink jet recording head HC3, and the ink jet recording head HK3 records in FIG. The dots 3 shown in FIG. 2 are recorded, and each of the landed ink droplets is irradiated with an active energy ray from the light irradiation device 5 to be cured, and then the dots shown in FIG. 2 are formed by the ink jet recording head HY4 of the ink jet recording head unit HU4. 3 and the dots 4 shown in FIG. 2 is recorded by the ink jet recording head HC4, the dot 2 shown in FIG. 2 is recorded by the ink jet recording head HK4, and the active energy is applied to each landed ink droplet from the light irradiation device 5. This is a method of curing by irradiating a line.

  FIG. 15 shows an ink landing state in each pass when such a recording method is used for an image obtained by solidifying Y, M, C, and K at 100%. FIG. 15 shows a state in which recording is performed using four thinning patterns which are different in each of the four colors and have complementary relations in each pass in order of recording in the four passes. Up to the fourth pass is shown together with the landing order of each pixel. The four colors are arranged with respect to the paper surface in the order shown in the figure, and are recorded in the landing order according to the conveyance direction of the recording medium indicated by the arrow for each pass.

  FIG. 15 is characterized in that the ink amount of dots during one-pass printing is small. As a result, the dot diameter is reduced and bleeding is less likely to occur, and it is possible to irradiate light once before the adjacent dots land with the same color ink. Banding is good. Since this example uses a pattern in which Y and K and C and M are arranged diagonally in adjacent 2 × 2 = 4 dots, bleeding between Y and K and / or C and M is likely to occur. It is effective when applied to. Compared to FIG. 3, since the amount of dot ink during one-pass printing is further reduced, the bleeding suppression effect is high.

  By taking such a landing order, for example, when the conveyance speed is set to 350 mm / sec, it varies depending on the distance between any two inkjet recording heads that discharge the same color ink, but the dots 1 to 4 of the same color With respect to all combinations of two arbitrary dots selected from four dots, the landing time difference can be adjusted to several hundreds msec, and at least one light irradiation can be performed during this time. The resolution of the image obtained by this method is twice that of the inkjet recording head unit HU1, and the maximum ink ejection amount of the image recorded by the inkjet recording head unit HU1 can be reduced. Banding resistance of a solid image in a portion with a large amount becomes good.

  FIG. 16 is a modification of FIG. 15 and uses a pattern in which C and K and Y and M are arranged obliquely in adjacent 2 × 2 = 4 dots, so C and K and / or Y and M are used. It is effective when it is applied to the case where inter-bleeding is likely to occur.

  FIG. 17 is a modification of FIG. 15 and uses a pattern in which C and Y and K and M are arranged diagonally in adjacent 2 × 2 = 4 dots, so C and Y and / or K and M are used. It is effective when it is applied to the case where inter-bleeding is likely to occur.

  The ink jet recording apparatus of the present invention is not limited to the two pass recording ink jet recording apparatus shown in FIG. 3 or the four pass recording ink jet recording apparatus shown in FIG. The above-described configuration capable of multi-pass recording and light irradiation is one of the preferred ink jet recording apparatuses.

  Further, the number of ink jet recording head units is not limited to the case of two stages shown in FIG. 3 or the case of four stages shown in FIG. 5, and the number of ink jet recording head units is one or more. It is also applied when configured with

  In addition, it is also preferable that the recording medium is reciprocally conveyed or circulated and conveyed in the same direction with respect to the inkjet recording head unit so as to perform recording of a plurality of passes. The number of ink jet recording head units and active energy irradiation devices can be reduced. This is particularly effective when the ink jet recording head unit is composed of one stage.

  For example, when recording an image with an inkjet recording head unit in which a recording medium is reciprocally conveyed by a conveying means such as a roller, a belt, or a drum, or circulated and conveyed in the same direction, and a plurality of nozzles are arranged in a direction perpendicular to the conveying of the recording medium. The ink jet recording head unit is moved in the nozzle arrangement direction in units of 1 / n of the nozzle arrangement interval in synchronization with the reciprocating conveyance or circulation conveyance of the recording medium, and 1 / n of the nozzle arrangement interval is obtained by n recording medium conveyance. It is preferable to record an image at a recording density.

  A drum is preferable as the conveying means for circulating in the same direction. For example, when an image is recorded with an inkjet recording head unit in which a plurality of nozzles are arranged in a direction orthogonal to the rotation direction (a direction parallel to the drum rotation axis), the recording medium is wound around a drum and synchronized with the drum rotation. Then, it is preferable to move the inkjet recording head unit in the nozzle arrangement direction in units of 1 / n of the nozzle arrangement interval, and to record an image at a recording density of 1 / n of the nozzle arrangement interval by n rotations of the drum.

  Hereinafter, a specific example of the preferred ink jet recording apparatus 1 will be described with reference to FIGS.

  FIG. 18 is a schematic diagram illustrating an example of an inkjet recording apparatus that conveys a recording medium with a belt.

  The ink jet recording apparatus according to the present embodiment shows a specific example of the ink jet recording apparatus according to the embodiment described with reference to FIG. 3, and the same reference numerals are used for members having the same configuration, and the description thereof is omitted. Only the added configuration will be described.

  The ink jet recording apparatus 1 includes a platen 2 that functions as a suction box, a perforated belt 4 as a conveying unit, a control unit 3, a paper feeding unit 7, a paper discharging unit 10, a gas-liquid separation unit 8, and a negative pressure generating unit. A pump 9 and an air tube 10 are provided.

  The platen 2 has a plurality of openings (not shown), and the back surface of the perforated belt 4 that faces the two inkjet recording head units HU1 and HU2 and the light irradiation device 5 disposed at the corresponding position. The air-liquid separation unit 8 and the pump 9 are connected via an air tube 10.

  An ink tank (not shown) for storing ink and an ink supply pump are connected to the two inkjet recording head units HU1 and HU2.

  The perforated belt 4 includes a recording medium suction hole and an ink suction hole, and is configured to be rotatable by a driving source such as a motor (not shown). The recording medium P faces the two inkjet recording head units HU1 and HU2. The recording medium P that has been transported to the position and finished recording is transported toward the paper discharge unit 10.

  The paper feed unit 7 stores a recording medium P made of a sheet, and conveys the recording medium P toward the perforated belt 4.

  The control unit 3 controls the operation of each unit of the inkjet recording apparatus 1.

  The recording medium P is conveyed from the sheet feeding unit 7 to the position of the perforated belt 4 according to a command from the control unit 3, sucked by the platen 2, and adsorbed to the perforated belt 4. Along with the rotation, the two ink jet recording head units HU1 and HU2 are conveyed to recording positions facing each other to record an image, and after each recording, irradiation with active energy rays is performed by the light irradiation device 5.

  When ink remaining on the nozzle surfaces of the two inkjet recording head units HU1 and HU2 is sucked by the platen 2, a large amount of mist (water droplets) containing ink is generated in the air tube 10 connected to the platen 2. The gas-liquid separation unit 8 separates the air and the ink liquid and stores only the ink liquid in a waste liquid tank (not shown) by suction from the pump 9.

  In the present embodiment, the recording medium P is sucked and held on the belt by suction, but the recording medium P can also be sucked and held on the belt by electrostatic suction.

  FIG. 19 is a schematic diagram illustrating an example of an inkjet recording apparatus in which the recording medium is roll paper.

  The ink jet recording apparatus 1 uses a platen 2 as a suction guide means having both functions of a roll paper as a recording medium P, a transport guide for transporting the recording medium P, and a box for sucking ink.

  The ink jet recording apparatus 1 in the present embodiment is similar to the ink jet recording apparatus 1 in the embodiment described with reference to FIG. 18, and the same reference numerals are used for members having the same configuration. Only the differences in configuration will be described.

  18 differs from the ink jet recording apparatus 1 of the embodiment of FIG. 18 in that a belt is not used as a transport unit for transporting the recording medium P, and the recording medium P is transported using a roll paper original winding roller 13 and a driving roller 14 as transport means. It is a point.

  The original winding roller 13 is supported so as to be rotatable about its axis, and the recording medium P is wound around the original winding roller 13 in advance. The drive roller 14 is rotatable about its axis and is rotated by a drive source such as a motor (not shown).

  The recording medium P led from the original winding roller 13 is led to the driving roller 14. As a result, a conveyance path for conveying the recording medium P is established. Then, when the driving roller 14 is rotated by a driving source such as a motor, the recording medium P is drawn out from the original winding roller 13, and the drawn recording medium P is conveyed to the driving roller 14.

  On the surface of the platen 2, recording medium suction holes and ink suction holes corresponding to the holes of the perforated belt 4 described with reference to FIG. 18 are formed. When the recording medium is transported, the recording medium P is transported while being attracted to the platen 2 by the recording medium suction hole or the ink suction hole, and at the time of ink suction, the nozzles of the two inkjet recording head units HU1 and HU2 together with the air from the ink suction hole. The ink adhering to the surface is sucked.

  According to this configuration, since it is not necessary to use a belt, the recording medium P can be transported with a simple configuration, and the size and cost of the apparatus can be reduced.

  It is also preferable that the recording medium is reciprocated with respect to the line-type ink jet recording head so that recording is performed by each of the forward and backward movements of the recording medium. The number of inkjet recording heads and active energy irradiation devices can be reduced. For example, in the above-described embodiment, the recording medium can be easily moved backward by rotating the original winding roller 13 as a driving roller in the winding direction of the original winding roller 13.

  FIG. 20 is a schematic diagram illustrating an example of an ink jet recording apparatus that transports a recording medium with a drum.

  The ink jet recording apparatus 1 uses a recording medium transport drum (hereinafter also simply referred to as a drum) as a transport guide for transporting the recording medium P.

  The ink jet recording apparatus 1 in the present embodiment is similar to the ink jet recording apparatus 1 in the embodiment described with reference to FIG. 18, and the same reference numerals are used for members having the same configuration. Only the differences in configuration will be described.

  In FIG. 20, reference numeral 11 denotes a drum, which is configured to be rotatable in a direction indicated by an arrow by a driving unit (not shown).

  18 differs from the ink jet recording apparatus 1 of the embodiment of FIG. 18 in that a belt is not used as a transport unit for transporting the recording medium P, and the recording medium P is transported using the drum 11 as a transport unit. The charging means 20 is provided as a means for electrostatic adsorption. When the recording medium P passes between the drum 11 and the charging unit 20, the recording medium P is charged by the charging unit 20 and electrostatically attracted to the drum 11.

  A one-stage ink jet recording head unit HU arranged in an arc shape is arranged to face the outer peripheral surface of the drum 11.

  The recording medium P made of sheet paper is conveyed from the paper feeding unit 7 to the position of the drum 11 according to a command from the control unit 3, electrostatically adsorbed to the drum 11, and inkjet recording as the drum 11 rotates. The image is recorded by being conveyed to a recording position facing the recording head unit HU.

  Here, in the above-described embodiments of FIGS. 18 and 19, the case where the inkjet recording head unit is configured in two stages by HU1 and HU2, and ink is ejected from each of HU1 and HU2 to record an image on a recording medium will be described. did.

  In the present embodiment, a case will be described in which an inkjet recording head unit is configured in one stage with HU, and an image is recorded on a recording medium by ejecting ink from the HU.

  In this embodiment, the case where the ink jet recording head unit is configured in one stage will be described. However, as in the above-described embodiment, the ink jet recording head units HU1 and HU2 are configured in two stages or more. In the case of being configured by the number of stages, the present embodiment can be applied to each stage.

  If the resolution of the inkjet recording head unit HU used is the same as the resolution in the nozzle arrangement direction of the image to be recorded, thinning recording is performed. If the resolution of the inkjet recording head unit HU is lower, the resolution is synchronized with drum rotation. The inkjet recording head unit HU is moved in the nozzle arrangement direction to record an image.

  The ink jet recording head unit HU is configured to be movable along a rotation axis direction of the drum 11, that is, a direction substantially perpendicular to the conveyance direction of the recording medium P (the rotation direction of the drum 11), and the recording medium P is moved along the conveyance direction. In the process of scanning, ink is ejected from the nozzles of the inkjet recording head unit HU to record a one-pass image on the recording medium P, and the active energy ray is irradiated by the light irradiation device 5, and the drum 11 rotates once. When one scanning is completed, the inkjet recording head unit HU is moved by a predetermined amount along the nozzle arrangement direction, and the drum 11 is further rotated once to perform image recording for the second pass and active energy rays generated by the light irradiation device 5 as described above. Irradiation takes place. These steps are repeated for the required number of passes to complete the image recording.

  If the resolution of the inkjet recording head unit HU to be used is the same as the resolution in the nozzle arrangement direction of the image to be recorded, it is only necessary to perform thinning recording every rotation of the drum, and it is necessary to move the inkjet recording head unit HU. Absent.

  The recording medium P on which the image has been recorded is released from the surface of the drum 11 by the separation unit, and is discharged to the paper discharge unit 10 through the belt-shaped transport unit 4.

  According to this configuration, when the recording medium is circulated with respect to the ink jet recording head unit and recording is performed in a plurality of passes, the recording medium P is brought into close contact with the drum 11 and rotated to thereby stably convey the recording medium. It becomes possible.

  In the present embodiment, recording of one pass or more is performed by one rotation of the drum 11, and image recording is completed by two or more rotations. By increasing the number of drum rotations, image recording can be performed in more passes without increasing the number of ink jet recording head units.

  In this embodiment, the recording medium P is attracted and held on the drum 11 by electrostatic attraction. However, a plurality of apertures are provided on the surface of the drum 11, and the inside is made negative by suction means such as a vacuum pump. By doing so, it is possible to attract and hold the recording medium P on the surface.

  Alternatively, a plurality of sheets may be simultaneously sucked and held on the drum 11 to perform image recording.

  In the ink jet recording apparatus of the present invention, examples of the active energy rays applied to the ink droplets that have landed on the recording medium include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays. It is preferable to use electron beams and ultraviolet rays, which are easy to handle, are easy to handle, and are widely used industrially. In the present invention, ultraviolet rays are particularly preferable.

  When using an electron beam, the amount of the electron beam to be irradiated is preferably in the range of 0.1 to 30 Mrad. If it is less than 0.1 Mrad, a sufficient irradiation effect cannot be obtained, and if it exceeds 30 Mrad, the support or the like may be deteriorated.

  When ultraviolet rays are used, the light source is, for example, a low pressure, medium pressure, high pressure mercury lamp, metal halide lamp, xenon lamp having a light emission wavelength in the ultraviolet region, cold cathode tube, hot cathode tube having an operating pressure of several hundred Pa to 1 MPa. A conventionally well-known thing, such as LED, is used.

  As the irradiation condition of the active energy ray, it is preferable that the active energy ray is irradiated for 0.01 to 5.0 seconds after the ink has landed on the recording medium. In order to record a high-definition image, it is particularly important that the irradiation timing is as early as possible.

  In the inkjet recording apparatus of the present invention, as a method for controlling the time from when the ink droplets land on the recording medium until the active energy ray is irradiated by the active energy ray irradiation light source, preferably the active energy ray irradiation light source This can be achieved by appropriately adjusting the distance between the nozzles of the inkjet recording head and the conveyance speed of the recording medium.

  In the present invention, it is more preferable to heat the back surface of the recording medium during recording or before and after recording. As the heating means, there is a method of bringing the recording medium into contact with a heating roller, a flat heater, or the like, and it can be appropriately selected. A preferable heating temperature range is 30 degrees or more and 70 degrees or less. When heated to 30 ° C. or higher, the gloss of the recorded material becomes good, and when it is 70 ° C. or lower, the recording medium is not deformed and the conveyance property is good.

  In the present invention, a drying step may be provided after irradiation with active energy rays. The drying means to be applied after irradiation is not particularly limited. For example, a method of drying the recording medium by bringing the back surface of the recording medium into contact with a heating roller or a flat heater, a means for blowing warm air on the recording surface with a dryer, or a decompression process. The method of removing volatile components by the above, drying by electromagnetic waves such as microwave drying, etc. can be appropriately selected or combined.

(Member of recording device)
The member of the recording apparatus used in the ink jet recording apparatus of the present invention is preferably a member having a low transmittance or reflectance with respect to the active energy ray in order to prevent irradiation of the active energy ray, for example, the head surface due to irregular reflection of ultraviolet rays.

  In addition, a method in which a shutter is mounted on the active energy ray irradiation unit is preferable. For example, when ultraviolet rays are used, the ratio of illuminance at the time of opening and closing the shutter is preferably shutter open / shutter close = 10 or more. The above is more preferable, and 10,000 or more is more preferable.

(Inkjet recording head)
In the ink jet recording apparatus of the present invention, an ink jet ink according to the present invention is ejected onto a recording medium using an ink jet recording head, and an image is recorded. The demand method or the continuous method may be used. As the discharge method, an electro-mechanical conversion method (for example, single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), electro-thermal conversion method (for example, thermal ink jet) Specific examples include a mold, a bubble jet (registered trademark) type, an electrostatic attraction method (for example, an electric field control type, a slit jet type, etc.), and a discharge method (for example, a spark jet type). However, any discharge method may be used.

(Line head type ink jet recording head)
In the ink jet recording apparatus of the present invention, as a recording method, an ink jet recording head having a line head method which is severely demanded for clogging is used. A line-type ink jet recording head is an ink jet recording head that is longer than the width of the recording medium, and even if it is a long head having a large number of nozzles, a plurality of ink jet recording heads are unitized to make it longer Even such a head can be preferably used. By using a line-type ink jet recording head, a carriage equipped with the recording head scans in a direction perpendicular to the direction in which the recording medium is conveyed, so that more recording can be performed in a shorter time than a serial head that records an image. It becomes possible to do it, and productivity improves dramatically.

<Inkjet ink>
Next, the inkjet ink according to the present invention will be described.

[Photoreactive resin]
The inkjet ink according to the present invention (hereinafter also simply referred to as ink) preferably contains a photoreactive resin.

  As the photoreactive resin, for example, a polymerization monomer, a polymerization oligomer, or the like can be used. As the polymerization monomer, a radical polymerizable monomer, a cationic polymerizable monomer and the like are preferable. It is also preferable to use a monofunctional, bifunctional, or trifunctional or higher polyfunctional monomer in combination. Conventionally known photo radical initiators and photo cationic initiators can be used.

  The effect of the present invention can be exerted in the water-based ultraviolet curable ink-jet ink. Examples of the water-based ultraviolet curable ink-jet ink include an ink containing an emulsion in which a polymerization oligomer is dispersed in water.

  In the present invention, as a photoreactive resin, a polymer compound having a plurality of side chains in a hydrophilic main chain and capable of crosslinking between side chains by irradiation with active energy rays (hereinafter referred to as active energy ray cross-linking). It is particularly preferable to use an organic polymer). Hereinafter, the active energy ray crosslinkable polymer will be described.

  Examples of the polymer compound having a plurality of side chains in the hydrophilic main chain according to the present invention and capable of crosslinking between the side chains by irradiating active energy rays include, for example, saponified polyvinyl acetate, polyvinyl acetal , Polyethylene oxide, polyalkylene oxide, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, or a derivative of the hydrophilic resin, and at least one selected from the group consisting of these copolymers In the hydrophilic resin, modified groups such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, and a photodepolymerization type are introduced into the side chain.

  As the side chain, nonionic, anionic and amphoteric (betaine compounds) are preferable, and in particular, when combined with an anionic pigment as a colorant, it is preferably nonionic or anionic from the viewpoint of ink storage stability. Particularly preferred is nonionic properties.

  In the hydrophilic main chain, a saponified product of polyvinyl acetate is preferable from the viewpoint of ease of introduction of side chains and handling, and the degree of saponification is preferably 77% or more and 99% or less. Further, the average degree of polymerization is preferably 200 or more and 4000 or less, more preferably 200 or more and 1800 or less from the viewpoint of handling, and the effect of the present invention can be more preferably exhibited at 200 or more and 500 or less. If the average degree of polymerization is 200 or more, the effect of thickening by drying is moderate, and the secondary color bleed when using the line head system is good. Further, when the average degree of polymerization is 500 or less, the discharge property after the discharge is stopped for a certain time, that is, the intermittent discharge property is good. The average degree of polymerization can be calculated according to Japanese Industrial Standard K 6726.

  The addition amount is preferably 1% by mass or more and 10% by mass or less with respect to the total amount of ink. If the addition amount is 1% by mass or more, the viscosity can be sufficiently increased during light irradiation and good bleeding resistance is obtained. If the addition amount is 10% by mass or less, the viscosity of the ink is adjusted to suit the ink jet recording head suitability. Furthermore, after the discharge is stopped for a certain period of time, the initial speed reduction is small.

  The modification rate of the side chain with respect to the hydrophilic main chain is preferably 0.8 mol% or more and 4.0 mol% or less, and is preferably 1.0 mol% or more and 3.5 mol% or less. From the viewpoint of If it is 0.8 mol% or more, sufficient fixing property is obtained, and if it is 4.0 mol% or less, storage stability is good.

  As the photodimerization-type modifying group, those in which a diazo group, a cinnamoyl group, a stilbazolium group, a stilquinolium group or the like is introduced are preferable. (Composition).

  The photosensitive resin described in JP-A-60-129742 is a compound represented by the following general formula (1) in which a stilbazolium group is introduced into a polyvinyl alcohol structure.

In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, and A- represents a counter anion.

  The photosensitive resin described in JP-A-56-67309 includes a 2-azido-5-nitrophenylcarbonyloxyethylene structure represented by the following general formula (2) in the polyvinyl alcohol structure, or the following general formula. It is a resin composition represented by (3) and having a 4-azido-3-nitrophenylcarbonyloxyethylene structure.

  Further, a modifying group represented by the following general formula (4) is also preferably used.

  In the formula, R represents an alkylene group or an aromatic ring. A benzene ring is preferred.

  As the photopolymerization type modifying group, for example, resins represented by the following general formula (5) shown in JP-A Nos. 2000-181062 and 2004-189841 are preferable from the viewpoint of reactivity.

In the formula, R ₂ represents a methyl group or a hydrogen atom, n represents 1 or 2, X represents — (CH ₂ ) m—COO—, —CH ₂ —COO— or —O—, and Y represents an aromatic ring. Or a single bond and m represent the integer of 0-6.

  Moreover, it is also preferable to use the photopolymerization type | mold modified group represented by following General formula (6) described in Unexamined-Japanese-Patent No. 2004-161942 for a conventionally well-known water-soluble resin.

In the formula, R ₃ represents a methyl group or a hydrogen atom, and R ₄ represents a linear or branched alkylene group having 2 to 10 carbon atoms.

  In the ink according to the present invention, it is preferable to add a water-soluble photopolymerization initiator. These compounds may be dissolved or dispersed in a solvent, or may be chemically bonded to the photosensitive resin.

  The water-soluble photopolymerization initiator to be applied is not particularly limited, but 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (HMPK) is particularly preferable from the viewpoint of mixing property and reaction efficiency. ), Thioxanthone ammonium salt (QTX), and benzophenone ammonium salt (ABQ) are preferable from the viewpoint of miscibility with an aqueous solvent.

  Furthermore, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (n = 1, HMPK) represented by the following general formula (7) from the viewpoint of compatibility with the resin, The ethylene oxide adduct (n = 2 to 5) is more preferable.

  In the formula, n represents an integer of 1 to 5.

  Other examples include benzophenones such as benzophenone, hydroxybenzophenone, bis-N, N-dimethylaminobenzophenone, bis-N, N-diethylaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone. Thioxanthones such as thioxatone, 2,4-diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and isopropoxychlorothioxanthone. Anthraquinones such as ethyl anthraquinone, benzanthraquinone, aminoanthraquinone and chloroanthraquinone. Acetophenones. Benzoin ethers such as benzoin methyl ether. 2,4,6-trihalomethyltriazines, 1-hydroxycyclohexyl phenyl ketone, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di ( m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-phenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-phenylimidazole dimer, 2- (P-methoxyphenyl) -4,5-diphenylimidazole dimer, 2-di (p-methoxyphenyl) -5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5- Diphenylimidazole dimer 2,4,5-triarylimidazole dimer, benzyldimethyl ketal, 2-benzyl-2-dimethyl Mino-1- (4-morpholinophenyl) butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-hydroxy-2-methyl-1-phenyl -Propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, phenanthrenequinone, 9,10-phenanthrenequinone, Benzoins such as methylbenzoin and ethylbenzoin, 9-phenylacridine, acridine derivatives such as 1,7-bis (9,9'-acridinyl) heptane, bisacylphosphine oxide, and mixtures thereof are preferably used. May be used alone or in combination.

  In addition to these water-soluble photopolymerization initiators, accelerators and the like can also be added. Examples of these include, for example, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, and triethanolamine.

  These water-soluble photopolymerization initiators are preferable even if they are grafted to the side chain with respect to the hydrophilic main chain.

  The polymer compound having a plurality of side chains in the hydrophilic main chain according to the present invention and capable of cross-linking between the side chains by irradiating active energy rays is the main chain side having a certain degree of polymerization. Since cross-linking is performed between the chains via a cross-linking bond, the effect of increasing the molecular weight per photon is significantly greater than that of an ultraviolet ray curable resin that is polymerized via a general chain reaction. As a result, a very high curing sensitivity was realized.

  In the active energy ray crosslinkable polymer used in the present invention, the number of crosslinking points can be completely controlled by the length of the hydrophilic main chain and the amount of side chains introduced, and the physical properties of the ink film can be controlled according to the purpose. It is.

[Color material]
As the coloring material used in the ink-jet ink according to the present invention, various dyes or pigments known in ink-jet can be used. From the combination with the ionicity of the side chain of the active energy ray-crosslinking resin, anionic Is preferred.

  The ink of the present invention is characterized in that ink of the same color is divided into a plurality of times and inkjet ink is ejected. The same color inks may have the same composition or different compositions.

(dye)
There is no restriction | limiting in particular as dye which can be used by this invention, Water-soluble dyes, such as an acid dye, a direct dye, and a reactive dye, a disperse dye, etc. are mentioned, It is an anionic dye.

<Water-soluble dye>
Examples of the anionic water-soluble dye that can be used in the present invention include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, diphenylmethane dyes, and the like. The specific compound is shown below. However, it is not limited to these exemplified compounds.

<C. I. Acid Yellow>
1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 42, 44, 49, 59, 61, 65, 67, 72, 73, 79, 99, 104, 110, 114, 116, 118, 121, 127, 129, 135, 137, 141, 143, 151, 155, 158, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 220, 230, 232, 235, 241, 242, 246,
<C. I. Acid Orange>
3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166, 168,
<C. I. Acid Red>
88, 97, 106, 111, 114, 118, 119, 127, 131, 138, 143, 145, 151, 183, 195, 198, 211, 215, 217, 225, 226, 249, 251, 254, 256, 257, 260, 261, 265, 266, 274, 276, 277, 289, 296, 299, 315, 318, 336, 337, 357, 359, 361, 362, 364, 366, 399, 407, 415,
<C. I. Acid Violet>
17, 19, 21, 42, 43, 47, 48, 49, 54, 66, 78, 90, 97, 102, 109, 126,
<C. I. Acid Blue>
1, 7, 9, 15, 23, 25, 40, 62, 72, 74, 80, 83, 90, 92, 103, 104, 112, 113, 114, 120, 127, 128, 129, 138, 140, 142, 156, 158, 171, 182, 185, 193, 199, 201, 203, 204, 205, 207, 209, 220, 221, 224, 225, 229, 230, 239, 249, 258, 260, 264, 278, 279, 280, 284, 290, 296, 298, 300, 317, 324, 333, 335, 338, 342, 350,
<C. I. Acid Green>
9, 12, 16, 19, 20, 25, 27, 28, 40, 43, 56, 73, 81, 84, 104, 108, 109,
<C. I. Acid Brown>
2, 4, 13, 14, 19, 28, 44, 123, 224, 226, 227, 248, 282, 283, 289, 294, 297, 298, 301, 355, 357, 413,
<C. I. Acid Black>
1, 2, 3, 24, 26, 31, 50, 52, 58, 60, 63, 107, 109, 112, 119, 132, 140, 155, 172, 187, 188, 194, 207, 222,
<C. I. Direct yellow>
8, 9, 10, 11, 12, 22, 27, 28, 39, 44, 50, 58, 79, 86, 87, 98, 105, 106, 130, 132, 137, 142, 147, 153,
<C. I. Direct orange>
6, 26, 27, 34, 39, 40, 46, 102, 105, 107, 118,
<C. I. Direct Red>
2, 4, 9, 23, 24, 31, 54, 62, 69, 79, 80, 81, 83, 84, 89, 95, 212, 224, 225, 226, 227, 239, 242, 243, 254,
<C. I. Direct Violet>
9, 35, 51, 66, 94, 95,
<C. I. Direct Blue>
1, 15, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 160, 168, 189, 192, 193, 199, 200, 201, 202, 203, 218, 225, 229, 237, 244, 248, 251, 270, 273, 274, 290, 291,
<C. I. Direct Green>
26, 28, 59, 80, 85,
<C. I. Direct Brown>
44, 106, 115, 195, 209, 210, 222, 223,
<C. I. Direct Black>
17, 19, 22, 32, 51, 62, 108, 112, 113, 117, 118, 132, 146, 154, 159, 169,
<C. I. Reactive Yellow>
2, 3, 7, 15, 17, 18, 22, 23, 24, 25, 27, 37, 39, 42, 57, 69, 76, 81, 84, 85, 86, 87, 92, 95, 102, 105, 111, 125, 135, 136, 137, 142, 143, 145, 151, 160, 161, 165, 167, 168, 175, 176,
<C. I. Reactive Orange>
1, 4, 5, 7, 11, 12, 13, 15, 16, 20, 30, 35, 56, 64, 67, 69, 70, 72, 74, 82, 84, 86, 87, 91, 92, 93, 95, 107,
<C. I. Reactive Red>
2, 3, 5, 8, 11, 21, 22, 23, 24, 28, 29, 31, 33, 35, 43, 45, 49, 55, 56, 58, 65, 66, 78, 83, 84, 106, 111, 112, 113, 114, 116, 120, 123, 124, 128, 130, 136, 141, 147, 158, 159, 171, 174, 180, 183, 184, 187, 190, 193, 194, 195, 198, 218, 220, 222, 223, 228, 235,
<C. I. Reactive Violet>
1, 2, 4, 5, 6, 22, 23, 33, 36, 38,
<C. I. Reactive Blue>
2, 3, 4, 5, 7, 13, 14, 15, 19, 21, 25, 27, 28, 29, 38, 39, 41, 49, 50, 52, 63, 69, 71, 72, 77, 79, 89, 104, 109, 112, 113, 114, 116, 119, 120, 122, 137, 140, 143, 147, 160, 161, 162, 163, 168, 171, 176, 182, 184, 191, 194, 195, 198, 203, 204, 207, 209, 211, 214, 220, 221, 222, 231, 235, 236,
<C. I. Reactive Green>
8, 12, 15, 19, 21,
<C. I. Reactive Brown>
2, 7, 9, 10, 11, 17, 18, 19, 21, 23, 31, 37, 43, 46,
<C. I. Reactive Black>
5, 8, 13, 14, 31, 34, 39,
<C. I. Food Black>
1, 2,
Etc.

(Pigment)
As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used, but they are anionic pigments. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include cyclic pigments, dye lakes such as acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.

  Specific organic pigments are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 138.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

<Dispersant>
As the water-soluble polymer dispersant for stably dispersing the pigment in the ink, the following water-soluble resin can be used, which is preferable from the viewpoint of ejection stability.

  As the water-soluble resin, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer are preferably used. Styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer It is a water-soluble resin such as.

  The content of the water-soluble resin with respect to the total amount of the ink is preferably 0.1 to 10% by mass, and more preferably 0.3 to 5% by mass.

  Two or more of these water-soluble resins can be used in combination.

<Anionic pigment>
The form of the anionic pigment used in the present invention is preferably a pigment in which the pigment is dispersed with an anionic polymer dispersant or an anion-modified self-dispersing pigment from the viewpoint of dispersion stability.

  The anionic polymer dispersant refers to a dispersant having an anionic group obtained by neutralizing an acidic group in a molecule with a basic compound. Examples of the basic compound used at this time include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and amines such as ammonia, alkylamine, and alkanolamine. In the present invention, amines are particularly preferable. .

  The anionic polymer dispersant preferably used in the present invention is not particularly limited as long as the molecular weight is 1000 or more. For example, polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer Acrylic resins such as coalescence, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer Styrene-acrylic resin such as polymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer , Styrene-maleic acid copolymer, styrene-maleic anhydride male Inic acid copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer Polymers, vinyl acetate copolymers such as vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer, and copolymers or resins such as salts thereof are, for example, carboxylic acid, sulfonic acid or phosphonic acid. Includes homopolymers, copolymers and terpolymers with acid functionality. Monomers that give acid functionality are, for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, mesaconic acid, fumaric acid, citraconic acid, vinyl acetic acid, acryloxypropionic acid, vinyl sulfonic acid, Styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, allylsulfonic acid, allylphosphonic acid, vinylphosphonic acid and vinylsulfonic acid.

  The anion-modified self-dispersing pigment preferably used in the present invention refers to a pigment having an anionic group on the surface and capable of being dispersed without a dispersant. An anionic self-dispersing pigment refers to a pigment in which an acidic group is modified and neutralized with a basic compound, thereby making the anionic group dispersible in water without a dispersant.

  The pigment particle having an acidic group on the surface means a pigment directly modified with an acidic group on the surface of the pigment particle, or an organic substance having an organic pigment mother nucleus and having an acidic group bonded directly or through a joint. .

  Examples of the acidic group (also referred to as polar group) include a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a boric acid group, and a hydroxyl group, preferably a sulfonic acid group and a carboxylic acid group, and more preferably a carboxylic acid group. It is an acid group.

  Acid group modifiers include sulfuric acid, fuming sulfuric acid, sulfur trioxide, chlorosulfuric acid, fluorosulfuric acid, amidosulfuric acid, sulfonated pyridine salt, sulfamic acid and other treatments containing sulfur atoms, and the pigment particle surface is oxidized. Carboxylating agents such as sodium hypochlorite and potassium hypochlorite that introduce carboxylic acid groups can be mentioned. Among them, a sulfonating agent such as sulfur trioxide, sulfonated pyridine salt or sulfamic acid, or a carboxylating agent is preferable. Examples of basic compounds that neutralize acidic groups include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and amines such as ammonia, alkylamines, and alkanolamines. In the present invention, amines are used. Is particularly preferred.

  Examples of a method for obtaining pigment particles having a polar group on the surface include WO97 / 48769, JP-A-10-110129, JP-A-11-246807, JP-A-11-57458, and 11-189739. In other words, the surface of the pigment particles described in JP-A-11, JP-A-11-323232, JP-A-2000-265094, etc. is oxidized with an appropriate oxidizing agent, so that at least a part of the pigment surface has a sulfonic acid group or a salt thereof. The method of introduce | transducing such polar groups is mentioned. Specifically, it is prepared by oxidizing carbon black with concentrated nitric acid, or in the case of color pigments by oxidizing with sulfamic acid, sulfonated pyridine salt, amide sulfuric acid, etc. in sulfolane or N-methyl-2-pyrrolidone. can do. In these reactions, the pigment dispersion can be obtained by removing and purifying the substance that has been excessively oxidized and becomes water-soluble. Moreover, when a sulfonic acid group is introduced onto the surface by oxidation, the acidic group may be neutralized with a basic compound as necessary.

  Other methods include a method of adsorbing the pigment derivatives described in JP-A-11-49974, JP-A-2000-273383, JP-A-2000-303014, etc. on the surface of pigment particles by a treatment such as milling, and the like. Examples include a method of dissolving the pigment described in 2002-179777, 2002-201401 and the like together with a pigment derivative in a solvent and then crystallization in a poor solvent. Pigment particles having a polar group can be obtained.

  In the present invention, the polar group may be free or in a salt state, or may have a counter salt. Examples of the counter salt include inorganic salts (lithium, sodium, potassium, magnesium, calcium, aluminum, nickel, ammonium) and organic salts (triethylammonium, diethylammonium, pyridinium, triethanolammonium, etc.), preferably 1 A counter salt having a valence.

  The average particle diameter of the pigment dispersion used in the inkjet ink according to the present invention is preferably 500 nm or less, more preferably 200 nm or less, preferably 10 nm or more and 200 nm or less, and more preferably 10 nm or more and 150 nm or less. If the average particle size of the pigment dispersion exceeds 500 nm, the dispersion becomes unstable. In addition, even when the average particle size of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the ink tends to deteriorate.

  The particle size of the pigment dispersion can be determined by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. It is also possible to obtain a particle image with a transmission electron microscope on at least 100 particles and perform statistical processing on the image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). Is possible.

  Various methods such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used as a method for dispersing the pigment.

  The content of the colorant that can be dispersed or dissolved in water used in the inkjet ink according to the present invention is preferably 1 to 10% by mass relative to the total mass of the ink.

(Water-soluble solvent)
As the solvent applicable to the ink according to the present invention, an aqueous liquid medium is preferably used, and as the aqueous liquid medium, a mixed solvent such as water and a water-soluble organic solvent is more preferably used. Examples of water-soluble organic solvents that are preferably used include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, etc.), polyhydric alcohols (eg, ethylene glycol, diethylene glycol). , Triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether) , Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol Monophenyl ether, propylene glycol monophenyl ether, etc.), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylene) Tolamine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocyclics (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (for example, dimethyl sulfoxide, etc.) and the like.

[Surfactant]
Surfactants preferably used in the ink according to the present invention include alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, Anionic surfactants such as fatty acid salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers, glycerin esters, Activators such as sorbitan esters, polyoxyethylene fatty acid amides, amine oxides, cationic surfactants such as alkylamine salts and quaternary ammonium salts, silicone surfactants, fluorosurfactants And the like. These surfactants can also be used as pigment dispersants, and anionic surfactants can be particularly preferably used.

[Various additives]
The ink according to the present invention may contain other conventionally known additives. For example, fluorescent brighteners, antifoaming agents, lubricants, preservatives, thickeners, antistatic agents, matting agents, water-soluble polyvalent metal salts, acid bases, pH adjusters such as buffers, antioxidants, surfaces These are tension adjusters, specific resistance adjusters, rust inhibitors, inorganic pigments and the like.

  In addition to the above description, the ink according to the present invention is publicly known depending on the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Various additives, such as viscosity modifiers, specific resistance regulators, film recording agents, ultraviolet absorbers, antioxidants, anti-fading agents, antifungal agents, rust inhibitors, etc. can be appropriately selected and used, For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, 57-74192, 57-87989, 60-72785, 61-146591, JP-A-1-95091 and 3-13376, etc. Anti-fading agents, fluorescent whitening agents described in JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-4-219266. be able to.

"recoding media"
The paper, coated paper, there is a non-coated paper, as the coated paper, the coating amount per 1m ² is one side 20g before and after of art paper, 1m ² per coated amount on one side 10g before and after the coated paper Examples include a light coated paper having a coating amount per 1 m ^{2 of} about 5 g on one side, a fine coated paper, a mat coated paper with a matte finish, a dull coated paper with a dull finish, and a newspaper. Non-coated paper includes printing paper A using 100% chemical pulp, printing paper B using 70% or more chemical pulp, printing paper C using 40% or more and less than 70% chemical pulp, and printing using less than 40% chemical pulp. Examples thereof include paper D, gravure paper containing mechanical pulp and subjected to calendar treatment. More details are described in detail in “Latest Paper Processing Handbook” edited by the Paper Processing Handbook Editorial Committee, published by Tech Times, “Printing Engineering Handbook” edited by the Japan Printing Society.

  The plain paper is 80 to 200 μm uncoated paper belonging to a part of uncoated paper, special printing paper and information paper. The plain paper used in the present invention includes, for example, high-grade printing paper, intermediate-grade printing paper, low-grade printing paper, thin-like printing paper, fine-coating printing paper, special printing paper such as fine-quality printing paper, foam paper, PPC paper, and others There are information sheets and the like. Specifically, there are the following sheets and various modified / processed sheets using these sheets, but the present invention is not particularly limited thereto.

  High quality paper and colored high quality paper, recycled paper, copy paper / colored paper, OCR paper, carbonless paper / colored paper, synthetic paper such as YUPO 60, 80, 110 microns, YUPO COAT 70, 90 microns, etc. Coated paper 90kg, Foam mat paper 70, 90, 110kg, Foamed PET 38 microns, Mitsuori-kun (above, Kobayashi recording paper), OK fine paper, New OK fine paper, Sunflower, Phoenix, OK Royal White, Export fine paper ( NPP, NCP, NWP, Royal White) OK Book Paper, OK Cream Book Paper, Cream Premium Paper, OK Map Paper, OK Ishikari, Cucumber, OK Foam, OKH, NIP-N (above, Shin Oji Paper), Gold Wang, Toko, export quality paper, special demand quality paper, book paper, book paper L, light cream book paper, elementary textbook Paper, continuous slip paper, high quality NIP paper, silver ring, gold yang, gold yang (W), bridge, capital, silver ring book, harp, harp cream, SK color, securities paper, opera cream, opera, KYP medical record, silvia HN, Excellent Foam, NPI Foam DX (Nippon Paper), Pearl, Kinryo, Uscream fine paper, Special Book Paper, Super Book Paper, Book Paper, Diamond Foam, Inkjet Foam (Mitsubishi Paper), Carpet V, carpet SW, white elephant, luxury publication paper, cream carpet, cream white elephant, securities / voucher paper, book paper, map paper, copy paper, HNF (above, Hokuetsu), phone book cover, Book paper, cream shirairai, cream shirairaifu, cream shirairaifu, DSK (above, Daishowa Paper), Sendai MP fine paper, Jiang, Thunderbird fine, hanging paper, colored paper base, dictionary paper, cream book, white book, cream fine paper, map paper, continuous slip paper (above, Chuetsu Pulp), OP gold cherry (Chuetsu), gold sand, reference book paper, Replacement certificate paper (white), form printing paper, KRF, white foam, color foam, (K) NIP, fine PPC, Kishu inkjet paper (above, made by Kishu Paper), Taiou, Bright Foam, Kant, Kant White, Dante , CM paper, Dante Comic, Heine, paperback book paper, Heine S, New AD paper, Uto + 9 Lilo Excel, Excel Super A, Kant Excel, Excel Super B, Dante Excel, Heine Excel, Excel Super C, Excel Super D, AD Excel, Excel Super E, New Bright Foam, New Bright NIP (above, made by Daio Paper), Sun Ring, Moon Ring, Unzen, Galaxy, Baiyun, Weiss, Moon Ring Ace, Baiyun Ace, Unzen Ace (above, Nippon Paper Industries), Taiou, Bright Foam, Brightnip (Nagoya Pulp), Peony A, Golden Pigeon, Special Peony, White Peony A, White Peony C, Silver Pigeon, Super White Peony A, Light Cream White Peony, Special Medium Quality Paper, White Pigeon, Super Medium Quality Paper, Blue Pigeon, Red Pigeon, Gold Pigeon M Snow Vision, Snow Vision, Gold Pigeon Snow Vision, White Pigeon M, Super DX, Hamanasu O, Red Pigeon M, HK Super Printing Paper (above, Honshu Paper), Stalinden (A・ AW), Star Elm, Star Maple, Star Laurel, Star Poplar, MOP, Star Cherry I, Cherry I Super, Cherry II Super, Star Cherry III, Star Cherry IV, Cherry III Super, Chi Such as Jerry IV Super (manufactured by Marusumi Paper), SHF (manufactured by Toyo Pulp), and TRP (manufactured by Tokai Pulp).

  As the various films, all commonly used films can be used. For example, there are a polyester film, a polyolefin film, a polyvinyl chloride film, a polyvinylidene chloride film, and the like. Also, resin-coated paper that is photographic recording paper, YUPO paper that is synthetic paper, and the like can be used.

  As the various ink jet recording media, an ink receiving layer is formed on the surface using an absorbent support or a non-absorbent support as a base material. Examples of the ink receiving layer include a coating layer, a swelling layer, and a fine void layer.

  The swelling layer absorbs ink when the ink receiving layer made of a water-soluble polymer swells. The fine void layer is composed of inorganic or organic fine particles having a secondary particle size of about 20 to 200 nm and a binder, and fine voids of about 100 nm absorb ink.

  In recent years, an inkjet recording medium in which the above-mentioned fine void layer is provided on a base material using RC paper in which both sides of a paper base material are coated with an olefin resin is preferably used in terms of photographic images.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

《Synthesis of active energy ray crosslinkable polymer compound》
(Synthesis of active energy ray crosslinkable polymer compound 1)
Active energy ray crosslinkable polymer compound 1 was synthesized according to the following method.

  Glycidyl methacrylate (58 g), p-hydroxybenzaldehyde (42 g), pyridine (3 g), and N-nitroso-phenylhydroxyamine ammonium salt (1 g) were placed in a reaction vessel and stirred in a water bath at 80 degrees for 8 hours.

  Next, 45 g of a polyvinyl acetate saponified product having an average degree of polymerization of 2200 and a saponification rate of 88% was dispersed in 225 g of ion-exchanged water, and then 4.5 g of phosphoric acid was added to this solution and p- (3- Methacryloxy-2-hydroxypropyloxy) benzaldehyde was added so that the modification rate was 3.0 mol% with respect to polyvinyl alcohol, and the mixture was stirred at 90 ° C. for 6 hours. After cooling the obtained solution to room temperature, 30 g of basic ion exchange resin was added and stirred for 2 hours.

  Thereafter, the ion exchange resin was filtered, and Irgacure 2959 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator was mixed at a rate of 0.5 g with respect to 100 g of a 15% aqueous solution, and then diluted with ion exchange water. As a result, an aqueous solution of 10% active energy ray-crosslinkable polymer compound 1 was obtained.

(Synthesis of Active Light Energy Ray Crosslinkable Polymer Compound 2)
In the synthesis of the actinic ray crosslinkable polymer compound 1, a polyvinyl acetate saponified product having an average degree of polymerization of 330 and a saponification rate of 88% is used as the polyvinyl acetate saponified product, and the modification rate is 3.0 mol%. A 10% aqueous solution of the active energy ray-crosslinkable polymer compound 2 was obtained in the same manner except that the amount of (3-methacryloxy-2-hydroxypropyloxy) benzaldehyde was appropriately adjusted.

<Preparation of ink set>
Ink sets 1 to 3 were prepared according to the following method.

(Preparation of pigment dispersion)
(Preparation of magenta pigment dispersion)
The following additives were mixed and dispersed using a sand grinder filled with 0.6 mm zirconia beads at a volume ratio of 50% to prepare a magenta pigment dispersion having a magenta pigment content of 15%. The average particle diameter of the magenta pigment particles contained in this magenta pigment dispersion was 120 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

C. I Pigment Red 122 15 parts Jonkrill 61 (styrene acrylic resin dispersant, manufactured by Johnson, solid content 30%) 10 parts Glycerin 15 parts Ion-exchanged water 67 parts (Preparation of black pigment dispersion)
Carbon black self-dispersion cabojet 300 manufactured by Cabot was diluted with ion-exchanged water to prepare a black pigment dispersion having a carbon black content of 15%. The average particle size of the carbon black particles contained in this black pigment dispersion was 130 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

(Preparation of yellow pigment dispersion)
The following additives were mixed and dispersed using a sand grinder filled with 0.6 mm zirconia beads at a volume ratio of 50% to prepare a yellow pigment dispersion having a yellow pigment content of 15%. The average particle size of the magenta pigment particles contained in this yellow pigment dispersion was 110 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

C. I Pigment Yellow 74 15 parts Jonkrill 61 (styrene acrylic resin dispersant, manufactured by Johnson, solid content 30%) 10 parts Glycerin 15 parts Ion-exchanged water 67 parts (Preparation of cyan pigment dispersion)
The following additives were mixed and dispersed using a sand grinder filled with 50% by volume of 0.6 mm zirconia beads to prepare a cyan pigment dispersion having a cyan pigment content of 15%. The average particle diameter of the cyan pigment particles contained in this cyan pigment dispersion was 130 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

C. I Pigment Blue 15 15 parts Jonkrill 61 (styrene acrylic resin dispersant, manufactured by Johnson, solid content 30%) 10 parts Glycerin 15 parts Ion-exchanged water 67 parts [Preparation of ink set 1]
(Preparation of magenta pigment ink 1)
Magenta pigment dispersion (solid content 15%) 20 parts Active energy ray crosslinkable polymer compound 1 aqueous solution (solid content 10%) 28 parts Propylene glycol 30 parts Ethylene glycol 10 parts Olphine E1010 (manufactured by Nissin Chemical) 1 part Prevention Glaze: Proxel GXL (manufactured by Avicia) 0.3 part Ion exchange water was added to finish to 100 parts.

(Preparation of black pigment ink 1)
A black pigment ink 1 was obtained in the same manner as in the preparation of the magenta pigment ink 1 except that a black pigment dispersion was used instead of the magenta pigment dispersion.

(Preparation of yellow pigment ink 1)
A yellow pigment ink 1 was obtained in the same manner as in the preparation of the magenta pigment ink 1 except that a yellow pigment dispersion was used instead of the magenta pigment dispersion.

(Preparation of cyan pigment ink 1)
Cyan pigment ink 1 was obtained in the same manner as in the preparation of magenta pigment ink 1 except that a cyan pigment dispersion was used instead of the magenta pigment dispersion.

  The magenta pigment ink 1, the black pigment ink 1, the yellow pigment ink 1 and the cyan pigment ink 1 prepared as above were used as an ink set 1.

[Preparation of ink set 2]
In the preparation of the magenta pigment ink 1, the black pigment ink 1, the yellow pigment ink 1, and the cyan pigment ink 1, in place of the 10% active energy ray-crosslinking polymer compound 1 aqueous solution, 10% active energy ray-crosslinking property is high. Magenta pigment ink 2, black pigment ink 2, yellow pigment ink 2 and cyan pigment ink 2 were prepared in the same manner except that the aqueous molecular compound 2 solution was used.

[Preparation of ink set 3]
(Preparation of magenta pigment ink 3)
Magenta pigment dispersion (solid content 15%) 20 parts Aqueous UV curable urethane acrylate resin emulsion (solid content 40%, manufactured by Taisei Kako Co., Ltd., trade name: WBR-839) 5 parts 2-pyrrolidinone 15 parts Ethylene glycol 10 parts Orphin E1010 (manufactured by Nissin Chemical Co., Ltd.) 1 part Antifungal agent: Proxel GXL (manufactured by Abyssia) 0.3 part Ion exchange water was added to finish to 100 parts.

(Preparation of black pigment ink 3)
In the preparation of the magenta pigment ink 3, the black pigment ink 3 and the yellow pigment ink 3 were similarly used except that a black pigment dispersion, a yellow pigment dispersion, and a cyan pigment dispersion were used instead of the magenta pigment dispersion. A cyan pigment ink 3 was obtained.

  The magenta pigment ink 3, the black pigment ink 3, the yellow pigment ink 3, and the cyan pigment ink 3 prepared above were used as an ink set 3.

<Recording images>
[Image recording method 1]
Image recording was performed using a line head type inkjet recording apparatus composed of the two inkjet recording head units shown in FIG.

  Each of the ink jet recording heads constituting the two ink jet recording head units has a piezo type having a nozzle diameter of 25 μm, a nozzle number of 512, a minimum liquid amount of 12 pl, and a nozzle density of 360 dpi (dpi represents the number of dots per 2.54 mm). The inkjet recording heads are configured to be an inkjet recording head unit HU1 (inkjet recording heads HK1, HC1, HM1, HY1) and an inkjet recording head unit HU2 (inkjet recording heads HK2, HC2, HM2, HY2), respectively. A line head type ink jet recording head unit having a maximum recording density of 360 × 360 dpi is arranged so as to cover the recording width perpendicular to the conveyance direction of the recording medium.

  The light source for irradiating active energy rays comprised a 160 W / cm metal halide lamp (manufactured by Nippon Battery Co., Ltd., MAN200 (N) L) to constitute a line head type active energy ray irradiating means (light irradiating device 5). Two sets of these were prepared and installed as shown in FIG. In this way, a line head type ink jet recording apparatus was produced.

  The ink set 1 was mounted on the ink jet recording head units HU1 and HU2 shown in FIG. 3, a recorded image was created at a conveyance speed of 300 mm / second, and irradiated from an active energy ray irradiation light source.

  The recording order (landing order) of each ink is the position of todd 1 and dot 4 from the ink jet recording heads HK1, HC1, HM1, and HY1 constituting the ink jet recording head unit HU1 in accordance with the dot landing order shown in FIG. Recorded. Next, from the inkjet recording heads HK2, HC2, HM2, and HY2 constituting the inkjet recording head unit HU2, recording is performed at the positions of the todd 2 and the dot 3, and after each recording, an active energy ray is irradiated to record the recorded image. Cured. Image recording was performed according to the above method, and this was designated as image recording method 1.

[Image recording method 2]
A flat panel heater is attached to the transport portion of the line head type ink jet recording apparatus having the configuration shown in FIG. 3 used in the image recording method 1 and the surface temperature is set to 60 ° C. An image recording method 2 was prepared in the same manner as in the image recording method 1 except that the ink jet set to be loaded and the conveyance speed of the recording medium were changed as shown in Table 1.

[Image recording method 3]
In the image recording method of image recording method 1, dots 1 and 4 were recorded by the inkjet recording heads HC1 and HY1 of the inkjet recording head unit HU1, and dots 2 and 3 were recorded by the inkjet recording heads HK1 and HM1. Further, this is the same as the image recording method 3 except that dots 2 and 3 are recorded by the inkjet recording heads HC2 and HY2 of the inkjet recording head unit HU2 and dots 1 and 4 are recorded by the inkjet recording heads HK2 and HM2. It was.

[Image recording method 4]
Image recording was performed using a line head type inkjet recording apparatus constituted by the four inkjet recording head units shown in FIG.

  Each of the ink jet recording heads constituting the four ink jet recording head units has a nozzle diameter of 25 μm, a nozzle number of 512, a minimum liquid amount of 12 pl, and a nozzle density of 180 dpi (where dpi represents the number of dots per 2.54 mm). Inkjet recording heads HU1 (inkjet recording heads HK1, HC1, HM1, HY1), inkjet recording head unit HU2 (inkjet recording heads HK2, HC2, HM2, HY2), inkjet recording head unit HU3 (inkjet recording head) Heads HK3, HC3, HM3 and HY3), an ink jet recording head unit HU4 (ink jet recording heads HK4, HC4, HM4 and HY4), Arranged so as to cover the perpendicular recording width in the conveying direction of the respectively recording medium, the maximum recording density is a line head type ink jet recording head unit is 360 × 360 dpi.

  The nozzle arrangement in each of these inkjet recording head units is such that the nozzle positions of the inkjet recording head unit HU1 and the inkjet recording head unit HU4, and the inkjet recording head unit HU2 and the inkjet recording head unit HU3 are equal in the vertical direction of the transport direction. It is arranged to be. Further, as shown in FIG. 21, the nozzle pitches of the ink jet recording head unit HU1 and the ink jet recording head unit HU2 are set to be shifted by a half pitch in the vertical direction of the transport direction. The active energy ray irradiation light source (light irradiation device 5) constituted a line head type active energy ray irradiation means by arranging 160 W / cm metal halide lamps (MAN200 (N) L manufactured by Nihon Battery Co., Ltd.). Four sets of these were prepared and installed as shown in FIG. In this way, a line head type ink jet recording apparatus was produced.

  Each ink jet recording head shown in FIG. 5 is mounted with the ink set 2 to create a recorded image at a conveyance speed of 400 mm / second, and after recording with each ink jet recording head unit, irradiation is performed from an active energy ray irradiation light source. did.

  The recording order (landing order) of each ink is recorded at the position of dot 1 from the ink jet recording head unit HU1 (ink jet recording heads HK1, HC1, HM1, HY1) according to the dot landing order shown in FIG. Recording is performed at the position of dot 2 from the recording head unit HU2 (inkjet recording heads HK2, HC2, HM2, HY2), and is performed at the position of dot 3 from the inkjet recording head unit HU3 (inkjet recording heads HK3, HC3, HM3, and HY3). Recording was performed, and recording was performed at the position of the dot 4 from the inkjet recording head unit HU4 (inkjet recording heads HK4, HC4, HM4, and HY4).

[Image recording method 5]
A flat panel heater is attached to the conveying portion of the line head type ink jet recording apparatus having the configuration shown in FIG. 5 used in the image recording method 4 and the surface temperature is set to 60 ° C. Further, each ink jet recording head unit An image recording method 5 was prepared in the same manner as in the image recording method 4 except that the ink jet set and the conveyance speed of the recording medium loaded in were changed as shown in Table 1.

[Image recording method 6]
Image recording was performed using a line head type ink jet recording apparatus provided with one ink jet recording head unit and one light irradiation device shown in FIG.

  The ink jet recording heads HK, HC, HM and HY constituting the ink jet recording head unit HU1 have a nozzle diameter of 25 μm, the number of nozzles 512, a minimum liquid amount of 12 pl, and a nozzle density of 360 dpi (where dpi represents the number of dots per 2.54 cm). The piezo-type ink jet recording head was disposed so as to cover the recording width perpendicular to the recording medium conveyance direction, and a line head type ink jet recording head having a maximum recording density of 360 × 360 dpi was recorded. The active energy ray irradiation light source (light irradiation device 5) constituted a line head type active energy ray irradiation means by arranging 160 W / cm metal halide lamps (MAN200 (N) L manufactured by Nihon Battery Co., Ltd.). In this way, a line head type ink jet recording apparatus was produced.

  The ink set 3 was attached to each ink jet recording head constituting the ink jet recording head unit shown in FIG. 1, a recorded image was created at a conveyance speed of 200 mm / second, and irradiated from an active energy ray irradiation light source.

[Image recording method 7]
Image recording was performed using a line head type ink jet recording apparatus in which the ink jet recording head having the structure shown in FIG.

  The inkjet recording heads HK, HC, HM and HY have a nozzle diameter of 25 μm, a nozzle number of 512, a minimum liquid amount of 12 pl, a nozzle density of 360 dpi (dpi represents the number of dots per 2.54 cm), respectively. A line head type ink jet recording head having a maximum recording density of 360 × 360 dpi was recorded with a recording head arranged so as to cover the recording width perpendicular to the conveyance direction of the recording medium.

  As the active energy ray irradiation light source, a 160 W / cm metal halide lamp (manufactured by Nippon Battery Co., Ltd., MAN200 (N) L) was arranged to constitute a line head type active energy ray irradiation means. Four sets of these were prepared and installed as shown in FIG. In this way, a line head type ink jet recording apparatus was produced.

  The ink set 3 was mounted on the ink jet recording head shown in FIG. 4, and a recorded image was created at a conveyance speed of 200 mm / second, and irradiated from an active energy ray irradiation light source.

<Evaluation of recorded images>
Each image created by the above image recording methods 1 to 7 was evaluated according to the following method.

[Evaluation of banding resistance]
In accordance with each of the image recording methods described above, a red solid image prepared by using a 10 cm × 10 cm magenta pigment ink and a yellow pigment ink on a coated paper (OK Top Coat Oji Paper Co., Ltd.) and a PET (polyethylene terephthalate) film as a recording medium. Was output, and the presence or absence of banding in the recorded solid image was visually observed, and banding resistance was evaluated according to the following criteria.

◎: No banding is observed ○: Vertical weak stripes are slightly generated in the transport direction △: Vertical stripes are slightly seen in the transport direction as a whole, but within a practically acceptable range ×: Transport direction In addition, the occurrence of vertical stripes is clearly observed. XX: The entire pattern is quite terrible and cannot be practically used. [Evaluation of color bleed resistance]
According to each of the image recording methods described above, the printing point is changed on a solid red image created using 10 cm × 10 cm magenta pigment ink and yellow pigment ink on coated paper (OK Top Coat, Oji Paper Co., Ltd.) as a recording medium. Thus, an image pattern in which black characters were arranged using black pigment ink was output.

  The recorded character image was visually observed for color mixing, and color bleed resistance was evaluated according to the following criteria.

◎: No color mixing at all ○: Color mixing is a little, but 7-point characters can be confirmed △: Color mixing is slightly, but 9-point characters can be confirmed, and is in a practically acceptable range ×: Color Mixing was severe and only 12-point characters could be confirmed. XX: Color mixing was quite severe and could not be confirmed even with 12-point characters [Evaluation of gloss]
According to each of the above image recording methods, “N2 Flowers (JIS 9204-2000)” was output as an output image to A4 coated paper (SA Kinfuji Oji Paper Co., Ltd.) as a recording medium, and an evaluation image sample was created. As panelists for image quality evaluation, 20 people were arbitrarily selected and visually evaluated for gloss. An offset print image created by offset printing (Printmaster GTO52 manufactured by Heidelberg) on the same recording medium was compared and evaluated as a reference sample. In the evaluation, the number of persons judged to have the same glossiness as that of the reference sample of the offset print image among the 20 panelists was totaled, and the glossiness was evaluated according to the following criteria.

A: 16 or more people evaluated to be equivalent to the reference sample of the offset print image ○: 13 to 15 people evaluated to be equivalent to the reference sample of the offset print image Δ: Number of people evaluated as being equal to 9 to 12 people X: Number of people evaluated as being equivalent to the reference sample of the offset printed image XX: Number of people evaluated to be equivalent to the reference sample of the offset printed image Table 1 shows the evaluation results obtained by 3 persons or less.

  As is clear from the results shown in Table 1, the images recorded using the ink jet recording apparatus having the configuration defined in the present invention used a low-absorbing recording medium and a non-absorbing recording medium in comparison with the comparative example. It can be seen that it is excellent in banding resistance at the time, and excellent in color bleed resistance and glossiness when using a low-absorbency recording medium.

It is a schematic top view showing an example of an ink jet recording apparatus in which an ink jet recording head unit composed of a plurality of ink jet recording heads and a light irradiation device are arranged. It is a schematic diagram which shows an example of each dot arrangement | positioning at the time of performing image recording. It is a schematic top view which shows an example of the inkjet recording device which arranged the some inkjet recording head unit and the some light irradiation apparatus. It is a schematic top view showing an example of an ink jet recording apparatus in which a plurality of ink jet recording heads and a plurality of light irradiation devices are alternately arranged. It is a schematic top view showing an example of an ink jet recording apparatus in which a plurality of ink jet recording head units and a plurality of light irradiation devices are alternately arranged. It is a schematic diagram which shows the landing order and position of the dot discharged from the inkjet recording head unit in the inkjet recording device shown in FIG. It is a schematic diagram which shows the landing order and position of the dot discharged from the inkjet recording head unit in the inkjet recording device shown in FIG. It is a schematic diagram which shows the modification of FIG. It is a schematic diagram which shows the modification of FIG. It is a schematic diagram which shows the modification of FIG. It is a schematic diagram which shows the modification of FIG. It is a schematic diagram which shows the modification of FIG. It is a schematic diagram which shows the modification of FIG. It is a schematic diagram which shows the landing order and position of the dot discharged from the inkjet recording head unit in the inkjet recording device shown in FIG. It is a schematic diagram which shows the landing order and position of the dot discharged from the inkjet recording head unit in the inkjet recording device shown in FIG. It is a schematic diagram which shows the modification of FIG. It is a schematic diagram which shows the modification of FIG. It is the schematic which shows an example of the inkjet recording device which conveys a recording medium with a belt. It is the schematic which shows an example of the inkjet recording device whose recording medium is roll paper. It is the schematic which shows an example of the inkjet recording device which conveys a recording medium with a drum. It is a bottom view showing the relationship of nozzle positions between inkjet recording head units.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 Platen 5 Light irradiation apparatus HU, HU1-HU4 Inkjet recording head unit N Nozzle P Recording medium

Claims (11)

A line-type inkjet recording head in which a plurality of nozzles that discharge ink that is cured by irradiation of active energy rays to a recording medium are arranged;
Conveying means for conveying the recording medium in a direction perpendicular to the direction in which the plurality of nozzles are arranged;
Irradiating means for irradiating the ink landed on the recording medium with active energy rays,
Recording on the recording medium with the same color ink is performed in a plurality of times, and at least one active energy ray is irradiated during the plurality of times of recording, and the active energy rays are irradiated after the final recording. An ink jet recording apparatus. The ink jet recording apparatus according to claim 1, wherein the resolution (dpi) of dots in the transport direction of the recording medium per recording is changed by changing the transport speed of the recording medium. By increasing the conveyance speed of the recording medium N times (N is an integer of 2 or more), the resolution (dpi) of dots in the conveyance direction of the recording medium per recording is 1 / N. The ink jet recording apparatus according to claim 1 or 2. 4. The recording according to claim 1, wherein dots are thinned out from the 2 × 2 dot matrix of the same color ink so as to be arranged obliquely, and recording is performed once with the same color ink. The inkjet recording apparatus described. The ink of the same color is at least one type constituting an ink jet ink set comprising three or more types of inks having different hues;
Of the two ink combinations selected from the three or more inks, a combination of two inks having the worst bleeding is set in advance.
4. One-time recording with various inks is performed by thinning out the dots of the two types of inks having the worst bleeding from the 2 × 2 dot matrix of various inks so as to be diagonally arranged. The ink jet recording apparatus according to any one of the above. The ink jet recording apparatus according to claim 1, wherein the active energy rays are ultraviolet rays. The inkjet recording apparatus according to claim 1, wherein the conveying unit is a belt. The inkjet recording apparatus according to claim 1, wherein the conveying unit is a drum. The inkjet according to any one of claims 1 to 8, wherein the recording medium is reciprocated with respect to the line-type inkjet recording head, and recording is performed by each of forward and backward movements of the recording medium. Recording device. The inkjet recording apparatus according to claim 1, wherein the recording medium is a sheet. The inkjet recording apparatus according to claim 1, wherein the recording medium is roll paper.

Images