JP2007136859A - Imaging method, printed matter and image recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging method which can produce printed matter showing excellent character quality and gloss, with capabiliy to record a high-definition image, and printed matter and an image recording device. <P>SOLUTION: In this imaging method, an inkjet recording head with a partition formed of an actuator which deformably operates in response to applied voltage, and a drive signal generating means which makes the actuator deformingly operate to generate a drive signal with a specified pause time set between an expansion pulse and a contraction pulse of an ink chamber are provided. Thus inkjet ink which is curable by an active light is discharged onto a recording material, using the inkjet recording head which discharges an ink droplet by expanding and contracting the ink chamber upon the drive signal, and has the pause time set to a crosstalk dwindling time. The inkjet ink contains at least a coloring material, water and a polymer compound which has a plurality of side chains in a hydrophilic main chain, and further, can become crosslinked between the side chains by irradiating with active energy beams. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming method, a printed material, and an image recording apparatus that are capable of recording a high-definition image with excellent character quality and that are excellent in gloss.

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

  In particular, in recent years, the recording speed has been greatly improved, and printers having performance capable of withstanding light printing applications have been developed. However, in order to bring out the performance of the ink jet printer, an ink jet special paper provided with ink absorbability is required.

  When recording on coated paper or art paper that does not absorb much ink, or on plastic film that does not absorb ink at all, there are problems such as so-called bleed that cause different color ink liquids to mix on the recording medium and cause color turbidity. However, it has been a problem in providing a variety of recording media to inkjet.

  In response to the above problems, a hot-melt ink composition made from a solid wax or the like at room temperature is used, liquefied by heating, etc., sprayed with some energy, cooled and solidified while adhering to the recording medium. A hot melt type ink jet recording method for forming recording dots has been proposed. However, an image recorded by such a method has problems such as deterioration in quality due to the rising of the dots and lack of scratching performance 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 ultraviolet rays is disclosed (see Patent Document 1). In addition, a so-called non-aqueous ink containing a pigment as an essential component and a triacrylate or higher polyacrylate as a polymerizable material and using a ketone and an alcohol as a main solvent has been proposed (Patent Document 2). reference). Further, an ink using a water-based ultraviolet polymerization monomer has been proposed (see Patent Document 3).

  In these methods, since the ink itself is cured with a curing component, recording is possible even on a non-absorbing medium. However, since the curing component other than the colorant is contained in a large amount and does not volatilize, the recording surface is reduced. The ink dots swelled up, causing unnaturalness in image quality, especially gloss.

  Furthermore, there is a safety concern for the conventionally known curable components, and even if the safety is cleared, there is a problem that the selection of materials and physical properties cannot be performed due to the narrow selection of materials. .

  On the other hand, piezo method, thermal method, continuous method, and the like are known as ink jet recording methods for discharging ink by an ink jet recording head. From the viewpoint of discharge stability, a piezo method using a piezoelectric member is known. Widely used. This piezo method is a method in which an ink droplet is ejected from an ink nozzle by changing the pressure in the ink chamber by an actuator such as a piezoelectric member that is deformed and operated according to an applied voltage. A general ink jet recording head is provided with a large number of ink chambers and ink nozzles from the viewpoint of forming a high-quality and high-definition image. There is a problem in that crosstalk that causes large fluctuations in the ink in the chamber occurs. As a result, the flying accuracy of ink droplets is reduced, which is a great hindrance to high-definition image formation.

As one of the methods for solving the above crosstalk, an expansion pulse for expanding the volume of the ink chamber by deforming the actuator constituting the ink chamber partition, and a contraction of the volume of the ink chamber by deforming the actuator. Drive signal generating means for continuously generating a drive signal to be applied to the actuator a plurality of times with a predetermined pause time between the contraction pulses to be generated, and ink is generated by generating the drive signal from the drive signal generating means a plurality of times A method of improving a chamber by repeatedly expanding and contracting the chamber volume to continuously discharge a plurality of ink droplets from the ink discharge port and setting the pause time to a time to reduce crosstalk between adjacent ink chambers. Has been proposed (see Patent Document 4). A combination of this technique and actinic ray curable ink (radical polymerization and cationic polymerization) has been disclosed (see Patent Document 5), but in these inks, the polymerizable component is used in an ink composition ratio of 50% or more. As a result, the printed portion is raised and the image has no gloss. Also, due to the solvent-based ink (low surface tension), there is a problem that plain paper causes feathering and back-through.
U.S. Pat. No. 4,228,438 Japanese Patent Publication No. 5-64667 JP-A-7-224241 Japanese Patent Laid-Open No. 2002-19103 JP 2004-188768 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image forming method, a printed material, and an image that are excellent in character quality, can record a high-definition image, and can obtain a printed material excellent in gloss. It is to provide a recording apparatus.

  The above object of the present invention is achieved by the following configurations.

1. A common arrangement in which a plurality of ink chambers provided with ink nozzles for ejecting ink droplets constituting a partition is arranged by an actuator that deforms in response to an applied voltage of an adjacent ink chamber, and ink is supplied to each of the ink chambers. An ink jet recording head provided with an ink chamber;
A predetermined pause is applied between an expansion pulse that expands the volume of the ink chamber by deforming the actuator constituting the ink chamber partition wall and a contraction pulse that contracts the volume of the ink chamber by deforming the actuator. Drive signal generating means for continuously generating a drive signal to be applied to the actuator multiple times,
The volume of the ink chamber is repeatedly expanded and contracted by generating the drive signal from the drive signal generating means a plurality of times, and a plurality of ink droplets are continuously ejected from the ink nozzle, and the pause time is set between adjacent ink chambers. In an image forming method of discharging an inkjet ink that is cured by actinic rays onto a recording material with an inkjet recording head set to a time for reducing the crosstalk of
The inkjet ink contains at least a colorant, water, and a high molecular 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. An image forming method.

  2. The pause time between the expansion pulse and the contraction pulse is set such that the time difference between the center of the expansion pulse and the center of the contraction pulse is equal to the natural vibration period of the ink in the ink chamber. 2. The image forming method according to 1.

  3. 3. The image forming method according to 1 or 2, wherein the inkjet ink contains a polymer compound in an amount of 0.8% by mass to 5.0% by mass with respect to the total mass of the ink.

  4). The hydrophilic main chain of the polymer compound contained in the inkjet ink is a saponified product of polyvinyl acetate, having a saponification degree of 77% to 99% and a polymerization degree of 200 to 4000. The image forming method according to any one of 1 to 3 above.

  5. 5. The polymer compound contained in the inkjet ink, wherein the modification rate of the side chain with respect to the hydrophilic main chain is 0.8 mol% or more and 4 mol% or less, The image forming method described in 1.

  6). A printed matter produced by the image forming method according to any one of 1 to 5 above, using a non-absorbent recording material.

  7). 6. An image recording apparatus used in the image forming method according to any one of 1 to 5 above.

  According to the present invention, it is possible to provide an image forming method, a printed material, and an image recording apparatus that are capable of recording a high-definition image with excellent character quality and that are excellent in gloss.

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

  The ink used in the image forming method of the present invention is a water-based ink, but when such an ink is used, the emission stability from the head is often unstable. In the recording head driving method described below, crosstalk has been improved, but the problem of droplet ejection properties after ejection has not been sufficient. In order to reduce such problems, the present invention can solve this problem by using the driving method according to the present invention for the driving method of the recording head as well as the idea for the ink composition. The droplet emission property here means not only ink ejection stability (does not eject), but also means that ink droplets after ejection do not form a chitin and ink splatter does not occur. The effect of improving the character quality was obtained. This is because the liquid droplet ejection property is improved when the ink contains the polymer compound according to the present invention, so that the wettability of the ink around the head nozzle is improved, and at the same time, the head driving conditions suitable for the liquid physical properties of the ink Was achieved.

  That is, as a result of intensive investigations in view of the above problems, the present inventor has found that an ink chamber provided with an ink nozzle that ejects ink droplets that form partition walls by an actuator that deforms in response to an applied voltage of an adjacent ink chamber. The ink jet recording head provided with a common ink chamber that supplies ink by communicating with each of the ink chambers and an actuator that forms the ink chamber partition are deformed to expand the volume of the ink chamber A drive signal generation that continuously generates a drive signal to be applied to the actuator by providing a predetermined pause time between the pulse and a contraction pulse that contracts the volume of the ink chamber by deforming the actuator. And repeatedly expanding and contracting the volume of the ink chamber by generating the drive signal from the drive signal generating means a plurality of times. A plurality of ink droplets are continuously ejected from the ink nozzle and the rest time is set to a time for reducing crosstalk between adjacent ink chambers. In the image forming method to be ejected, the inkjet ink has at least a colorant, water, and a plurality of side chains in a hydrophilic main chain, and can be cross-linked between the side chains by irradiating active energy rays. It has been found that an image forming method characterized by containing a polymer compound can realize an image forming method that is capable of recording high-definition images with excellent character quality, and capable of obtaining printed matter with excellent gloss. It is up to the present invention.

  Details of the present invention will be described below.

<Image recording device>
First, the details of the image recording apparatus used in the image forming method of the present invention will be described with reference to the drawings as appropriate. Note that the image recording layer device or the ink jet recording head (hereinafter also simply referred to as a recording head) in the drawings is an embodiment that can be used in the recording method or the image recording device of the present invention, and the present invention is included in these drawings. It is not limited only to the contents described.

  FIG. 1 is a front view showing a configuration of a main part of the image recording apparatus of the present invention.

  The image recording apparatus A includes a head carriage B, a recording head C, an irradiation unit D, a platen unit E, and the like. In the image recording apparatus A, a platen portion E is installed under a recording material P. The platen portion E has a function of absorbing ultraviolet rays and absorbs extra ultraviolet rays that have passed through the recording material P. As a result, a high-definition image can be reproduced very stably.

  The recording material P is guided by the guide member F, and moves from the near side to the far side in FIG. 1 by the operation of the conveying means (not shown). Head scanning means (not shown) scans the recording head C held by the head carriage B by reciprocating the head carriage B in the Y direction in FIG.

  The head carriage B is installed on the upper side of the recording material P, and accommodates a plurality of recording heads C, which will be described later, in accordance with the number of colors used for image printing on the recording material P, with the discharge ports arranged on the lower side. The head carriage B is installed with respect to the main body of the image recording apparatus A in a form that can reciprocate in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by driving the head scanning means.

  In FIG. 1, the head carriage B is illustrated as accommodating a recording head C of white (W), yellow (Y), magenta (M), cyan (C), black (K), and white (W). In practice, the number of colors of the recording head C stored in the head carriage B can be determined as appropriate.

  Although details of the recording head will be described later, the recording head C includes a plurality of actinic ray curable inks (for example, ultraviolet curable inks) supplied by an ink supply unit (not shown). The recording material P is discharged from the discharge port by the operation of the discharge means (not shown). The ultraviolet curable ink ejected by the recording head C is composed of a coloring material, a crosslinkable polymer compound, an initiator, and the like, and the initiator acts as a catalyst when irradiated with ultraviolet rays. It has the property of being cured by the accompanying cross-linking reaction.

  During a scan in which the recording head C moves from one end of the recording material P to the other end of the recording material P in the Y direction in FIG. 1 by driving the head scanning means, a certain area (landing possible area) in the recording material P In contrast, the ultraviolet curable ink jet ink according to the present invention (hereinafter also simply referred to as ink) is ejected as ink droplets, and the ink droplets are landed on the landable region.

  The above scanning is performed as many times as necessary, and after ink is ejected toward one landable area, the recording material P is appropriately moved from the front to the back in FIG. 1 by the conveying means, and scanning by the head scanning means is performed again. In the meantime, the recording head C discharges ink to the next landable area adjacent to the rearward direction in FIG.

  By repeating the above-described operation and ejecting ink from the recording head C in conjunction with the head scanning unit and the conveying unit, an image composed of an aggregate of ink droplets is formed on the recording material P.

  Next, details of a driving method for preventing crosstalk with the inkjet recording head according to the present invention will be described.

  As an ink jet recording head, an on-demand ink jet recording head in which a partition between adjacent ink chambers is configured by an actuator such as a piezoelectric member is known. This head has an advantage that a large number of ink chambers partitioned by partition walls can be easily arranged at high density.

  For example, as shown in FIGS. 2 and 3, an ink jet recording head using a piezoelectric member as an actuator has two rectangular piezoelectric members 1 and 2 whose polarization directions are opposite to each other in the plate thickness direction. The piezoelectric members 1 and 2 are fixed to the substrate 3 having a dielectric constant lower than that of the piezoelectric member, and the piezoelectric members 1 and 2 are parallel with the same width at regular intervals using, for example, a diamond cutter. A plurality of long grooves having the same depth and the same length are cut to form the ink chamber 4.

  Electrodes 5 are formed by electroless nickel plating on the side and bottom surfaces of the ink chamber 4, and electrodes 6 are also formed by electroless nickel plating on the rear upper surface of the substrate 3 from the rear end of the ink chamber 4. A circuit board 7 having a drive circuit formed on the upper end face is bonded and fixed.

  A frame-like member 9 constituting a common ink chamber 8 is bonded and fixed on the ink chamber 4 of the piezoelectric members 1 and 2, and an ink supply port 10 that communicates with the common ink chamber 8 on the frame-like member 9. It is closed by the top plate 11 provided with. Further, an orifice plate 13 provided with a plurality of ink discharge ports 12 at the tip of each of the piezoelectric members 1 and 2 is bonded and fixed with an adhesive.

  Next, the operating principle of this ink jet recording head will be described.

  In FIG. 4A, paying attention to the five ink chambers 4a, 4b, 4c, 4d, and 4e, the electrodes 5a to 5e of the ink chambers 4a to 4e are set to the ground potential, and the electrodes of the central ink chamber 4c. When a positive voltage is applied to 5c, the piezoelectric members 1 and 2 have their polarization directions facing outward as indicated by arrows in the figure, so that both sides of the ink chamber 4c contract the volume of the ink chamber 4c due to shear strain. Deform inward as you do.

  Further, a positive voltage is applied to the electrodes 5a, 5b, 5d, and 5e of the ink chambers 4a, 4b, 4d, and 4e adjacent to the central ink chamber 4c with the electrodes 5a to 5e of the ink chambers 4a to 4e at the ground potential. When applied, as shown in FIG. 4 (b), both side surfaces of the electrode 5c of the ink chamber 4c are deformed outward so as to enlarge the volume of the ink chamber 4c. By utilizing such deformation of the ink chamber, ink droplets are ejected from the ink chamber. Specifically, the volume of the ink chamber is enlarged and the ink chamber 8 is filled with ink from the common ink chamber 8, and then the volume of the ink chamber is contracted to increase the pressure in the ink chamber from the ink discharge port 12. Ink droplets are ejected.

  Next, a method for driving the ink jet recording head according to the present invention will be described.

  FIG. 5 is a block diagram showing a configuration of the ink jet recording head driving apparatus according to the present embodiment. In FIG. 5, 21 is a printer controller that controls each part, 22 is an image memory that stores print data from the printer controller 21, and 23 is print data that is controlled by the printer controller 21 and stored in the image memory 22. The print data transfer block is transferred to the head drive circuit 24.

  The head drive circuit 24 drives the inkjet recording head 25 based on the print data transferred from the print data transfer block 23. A drive waveform when the head drive circuit 24 drives the ink jet recording head 25 is controlled by a drive waveform control circuit 26, and this drive waveform control circuit 26 is controlled by the printer controller 21.

  The ink jet recording head 25 used in the present invention is a share mode type ink jet recording head, and the configuration thereof is the same as that of the ink jet recording head shown in FIGS.

  6 to 8 are diagrams illustrating driving waveforms when the head driving circuit 24 drives the ink chambers of the ink jet recording head 25. FIG. In the drawing, i-3, i-2, i-1, i, i + 1, i + 2, and i + 3 indicate ink chambers that are continuously connected.

  FIG. 6 shows a driving waveform when a positive voltage is applied to each of the ink chambers i-3 to i + 3 at a predetermined timing to perform 7-drop driving, and FIG. 7 shows the voltage applied to the ink chamber that does not operate as the ground potential. The drive waveforms when the ink chambers i-3 to i + 3 are each driven with 7 drops are shown.

  The ink chamber performs the same operation regardless of whether the drive waveform of FIG. 6 or the drive waveform of FIG. 7 is used. Here, the case where the ink chamber is driven using the drive waveform of FIG. State.

  In this share mode type recording head, the i-3th, ith, and i + 3th ink chambers are driven simultaneously, but the i ± 2nd and i ± 1st ink chambers in between are not driven simultaneously, The i-2th and i + 1th ink chambers are driven simultaneously, but the ith and i-1th ink chambers in between are not driven simultaneously, and the i-1th and i + 2th ink chambers are driven simultaneously. The i-th and i + 1-th ink chambers in between are driven in three divisions so that they are not driven simultaneously. The ink chamber adjacent to the ink chamber driven by the three-division driving is directly affected, for example, so that erroneous ink ejection or the like does not occur.

  Each drive waveform W3 shown in FIG. 7 is a series of seven drive pulses W4 having the configuration shown in FIG. 8. Each drive pulse W4 is applied with an expansion pulse W4a that is a negative voltage pulse for expanding the ink chamber and pulse application. Is formed by a rest time W4b for stopping the ink and a contraction pulse W4c which is a positive voltage pulse for contracting the ink chamber.

  The ink jet recording head is driven by 1 drop for discharging one small ink droplet when one drive pulse W4 is applied, and is driven by 1 to 7 drops by connecting the drive pulses W4 in a range of 1 to 7 Thus, 7 gradation printing is possible except white.

  The time difference between the center of the expansion pulse W4a and the center of the contraction pulse W4c is 2AL, which is set to a time equal to the natural vibration period of the ink in the ink chamber. The pulse time width of the expansion pulse W4a is set to 1AL, and the pulse time width of the contraction pulse W4c is set in the range of 0.6AL to 1AL, here 1AL. Note that AL is a unit of time, and is the time for the pressure in the ink chamber to reverse from positive pressure to negative pressure or from negative pressure to positive pressure due to natural vibration, which is half of the natural vibration period of ink in the ink chamber. It's time.

  Next, the pressure change in the ink chamber when the drive pulse shown in FIG. 8 is applied to the ink chamber of the inkjet recording head 25 will be described with reference to FIG. First, the expansion pulse W4a expands the volume of the ink chamber at the falling edge of the waveform, and the internal ink pressure becomes the negative pressure P1. When the time of 1AL has elapsed from the fall of the waveform, the ink pressure in the ink chamber becomes positive pressure P2 due to natural vibration. Further, when the expansion pulse W4a ends, the ink chamber contracts, the ink pressure further increases from P2 to P3, and ink discharge is started from the ink discharge port of the ink chamber.

  When a time of about 0.5 AL has elapsed since the start of ink ejection, the pressure of the ink in the ink chamber changes to a negative pressure P4 due to natural vibration. Then, when 1AL has elapsed from the rise of the expansion pulse W4a, the ink ejection ends. At that time, the pause time W4b ends, the ink chamber contracts by the rise of the contraction pulse W4c, and the negative pressure state of the ink chamber is relaxed from P5 to P6.

  At the time when 1 AL has elapsed from the rise of the contraction pulse W4c, the ink pressure is positive pressure P7. At that time, the contraction pulse W4c falls, the contracted ink chamber returns to the original state, and the pressure in the ink chamber becomes almost zero. As described above, by applying the drive pulse shown in FIG. 8 to the ink chamber of the ink jet recording head, the residual pressure vibration having the natural vibration frequency of the ink that easily generates crosstalk can be made substantially zero.

  Further, a drive pulse W6 as shown in FIG. 10 may be used as the drive pulse. This drive pulse W6 is obtained by reducing the pulse time width of the contraction pulse W6c while keeping the time difference between the center of the expansion pulse W6a and the center of the contraction pulse W6c at 2AL, and the rest time W6b is longer than 1AL accordingly. Become.

  Such a drive pulse W6 is effective in the case of a head in which, for example, the pressure vibration generated by the expansion pulse W6a is attenuated at the time of applying the contraction pulse W6c. There is an effect that the residual pressure vibration can be further attenuated.

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

  In the image forming method of the present invention, by using the ink-jet ink according to the present invention, an excellent gloss can be obtained unlike the conventionally known ultraviolet curable ink (solvent-based ink). In addition, there is an advantage that crosstalk is reduced by adding a small amount of the water-soluble polymer according to the present invention to the ink. Further, in the case of ink having such a composition and the above driving conditions, it is considered that the discharged ink droplets are very stable and the scattering is reduced, so that the character quality is greatly improved.

[Active energy ray crosslinkable polymer compound]
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 with active energy rays is a saponified product of polyvinyl acetate, polyvinyl acetal, polyethylene Oxide, polyalkylene oxide, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, or a derivative of the hydrophilic resin, and at least one hydrophilic selected from the group consisting of these copolymers In the resin, a modified group such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, or a photodepolymerization type is introduced into the side chain. Photopolymerizable crosslinkable groups are desirable from the viewpoints of sensitivity and performance of the generated image.

  In the hydrophilic main chain, a saponified product of polyvinyl acetate is preferable from the viewpoint of convenience for introduction of side chains and handling, and the polymerization degree is preferably 200 or more and 4000 or less, and 200 or more and 2000 or less is a viewpoint of handling. Is more preferable. The modification rate of the side chain with respect to the main chain is preferably 0.3 mol% or more and 4 mol% or less, and more preferably 0.8 mol% or more and 4 mol% or less from the viewpoint of reactivity. If it is less than 0.3 mol%, the crosslinkability is insufficient and the effect of the present invention is reduced. If it is more than 4 mol%, the crosslink density is increased and the film is hard and brittle, and the strength of the film is lowered.

  As the photodimerization-type modifying group, those in which a diazo group, a cinnamoyl group, a stilbazonium group, a stilquinolium group or the like is introduced are preferable. For example, a photosensitive resin described in JP-A-60-129742 (Composition).

  The photosensitive resin described in JP-A-60-129742 is a compound represented by the following general formula (1) in which a stilbazonium 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. This 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, a resin represented by the following general formula (5) shown in JP-A Nos. 2000-181062 and 2004-189841 is 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— or —O—, and Y represents an aromatic ring or a single bond. And m represents an integer from 0 to 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.

  Such an active energy ray-crosslinking resin is preferably contained in an amount of 0.8% by mass to 5.0% by mass relative to the total mass of the ink. The presence of 0.8% by mass or more improves cross-linking efficiency, and beading and color bleeding are more preferable due to a rapid increase in ink viscosity after cross-linking. If it is 5.0% by mass or less, it is difficult to adversely affect the ink physical properties and the state in the ink head, which is preferable from the viewpoint of the emission property and the ink storage property. Further, crosstalk in the recording method is less likely to occur, and printing and swell are reduced, which is preferable in terms of gloss.

  In such an active energy ray-crosslinked polymer compound, the main chain originally having a certain molecular weight is cross-linked between the side chains through a cross-linking bond. The effect of increasing the molecular weight per photon is remarkably large compared to a conventionally known active energy ray-curable resin produced by polymerization. On the other hand, since conventionally known active energy ray curable resins cannot control the number of crosslinking points, the physical properties of the cured film cannot be controlled, and they tend to be hard and brittle.

  In the resin 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.

  Furthermore, since ink using a conventionally known active energy ray-curable resin is a component that is involved in curing almost all of the materials other than the color material, the dots after curing rise and the image quality represented by gloss is significantly deteriorated. On the other hand, the ink-jet ink according to the present invention requires a small amount of the crosslinkable polymer compound and has a large amount of dry components, so that the image quality after drying is improved and the fixability is also good.

[Photopolymerization initiator, sensitizer]
In the present invention, it is also preferable to add a photopolymerization initiator or a sensitizer. These compounds may be dissolved or dispersed in a solvent, or may be chemically bonded to the photosensitive resin.

  There are no particular restrictions on the photopolymerization initiator and photosensitizer to be applied, and conventionally known ones can be used. From the viewpoints of water-soluble photopolymerization initiator and photosensitizer being miscible and reaction efficiency. preferable. In particular, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (HMPK), 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 -2,4,5-triarylimidazole dimer of diphenylimidazole dimer, benzyldimethyl ketal, 2-benzyl-2-dimethyl Amino-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 photopolymerization initiators, accelerators and the like can also be added. Examples of these include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, triethanolamine and the like.

  Even if these photoinitiators are grafted to the side chain with respect to the hydrophilic main chain.

(Colorant)
As the colorant used in the ink-jet ink of the present invention, various dyes or pigments known in ink-jet can be used, but in combination with the ionicity of the side chain of the active energy ray-crosslinking resin, Preferably there is.

(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, An anionic dye is preferable.

[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. Basic Yellow>
1, 2, 11, 13, 15, 19, 21, 28, 29, 32, 36, 40, 41, 45, 51, 63, 67, 70, 73, 91,
<C. I. Basic Orange>
2, 21, 22,
<C. I. Basic Red>
1, 2, 12, 13, 14, 15, 18, 23, 24, 27, 29, 35, 36, 39, 46, 51, 52, 69, 70, 73, 82, 109,
<C. I. Basic Violet>
1, 3, 7, 10, 11, 15, 16, 21, 27, 39,
<C. I. Basic Blue>
1, 3, 7, 9, 21, 22, 26, 41, 45, 47, 52, 54, 65, 69, 75, 77, 92, 100, 105, 117, 124, 129, 147, 151,
<C. I. Basic Green>
1, 4,
<C. I. Basic Brown>
1,
<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.

  Furthermore, examples of the dye include a compound represented by the following general formula (8) or a compound represented by the general formula (9).

In the general formula (8), R ₁ represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom or a phenylcarbonyl group. R ₂ may be different and represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom. R ₃ represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom or an alkyl group. R ₄ represents a hydrogen atom or a substitutable substituent, preferably a hydrogen atom or an aryloxy group. R ₅ may be different and represents a hydrogen atom or a substitutable substituent, and is preferably a sulfonic acid group. n represents an integer of 1 to 4, and m represents an integer of 1 to 5.

In the general formula (9), X represents a phenyl group or a naphthyl group, may be substituted with a substitutable substituent, and is preferably substituted with a sulfonic acid group or a carboxyl group. Y represents hydrogen ion, sodium ion, potassium ion, lithium ion, ammonium ion or alkylammonium ion. R ₆ may be different and represents a hydrogen atom or a substituent that can be substituted on the naphthalene ring. q represents 1 or 2. p represents an integer of 1 to 4. However, q + p = 5. Z represents a substitutable substituent, and represents a carbonyl group, a sulfonyl group or a group represented by the following general formula (10), and particularly preferably a group represented by the following general formula (10).

In the general formula (10), W ₁ and W ₂ each independently represent a halogen atom, amino group, hydroxyl group, alkylamino group or arylamino group, preferably a halogen atom, hydroxyl group or alkylamino group.

[Disperse dye]
As the disperse dye, various disperse dyes such as azo disperse dyes, quinone disperse dyes, anthraquinone disperse dyes, quinophthalone disperse dyes can be used, and specific compounds thereof are listed below.

<C. I. Disperse Yellow>
3, 4, 5, 7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 108, 114, 116, 118, 119, 122, 124, 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 184, 186, 192, 198, 199, 202, 204, 210, 211, 215, 216, 218, 224, 227, 231, 232,
<C. I. Disperse Orange>
1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 47, 48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142,
<C. I. Disperse Red>
1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151, 152, 153, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 23 , 240,257,258,277,278,279,281,288,298,302,303,310,311,312,320,324,328,
<C. I. Disperse Violet>
1, 4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77,
<C. I. Disperse Green>
9,
<C. I. Disperse Brown>
1, 2, 4, 9, 13, 19,
<C. I. Disperse Blue>
3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 79, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 154, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 3 0,333,
<C. I. Disperse Black>
1, 3, 10, 24
Etc.

  These dyes listed above are described in “Dyeing Note 21st Edition” (published by Color Dyeing Co., Ltd.) and the like.

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

  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.

  As a method for dispersing the pigment, for example, various dispersing machines 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. It is also preferable to use a centrifugal separator or a filter for the purpose of removing the coarse particles of the pigment dispersion.

  In the ink of the present invention, a self-dispersed pigment in which polar groups such as sulfonic acid and carboxylic acid are pendant on the pigment surface, or a pigment dispersed using a polymer dispersant is preferable.

  The polymer dispersant applicable to the present invention is not particularly limited, and a water-soluble resin or a water-insoluble resin is used. Examples of these polymers include styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, methacrylic acid, methacrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid. Examples thereof include a polymer composed of a single monomer selected from acid derivatives, a copolymer composed of two or more monomers, and salts thereof. Water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives, gelatin, and polyethylene glycol can also be used.

  The content of these water-soluble resins with respect to the total amount of ink is preferably 0.1 to 10% by mass, and more preferably 0.3 to 5% by mass. These water-soluble resins can be used in combination of two or more.

  The average particle size of the pigment dispersion used in the inkjet ink of 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.

(Water-soluble solvent)
As a solvent applicable to the ink of the present invention, an aqueous liquid medium is preferably used, and 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), polyhydric alcohols (eg, ethylene glycol, diethylene glycol, Triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether, ethylene Glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Nomethyl 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), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetra) , Tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2 -Pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone), sulfoxides (for example, dimethyl sulfoxide) and the like.

[Surfactant]
Surfactants preferably used in the ink of the present invention include alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, fatty acids. Anionic surfactants such as salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers, glycerin esters, sorbitan Activators such as esters, polyoxyethylene fatty acid amides and amine oxides, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

  These surfactants can also be used as pigment dispersants, and anionic surfactants can be particularly preferably used.

[Various additives]
The ink of the present invention may contain other conventionally known additives. For example, optical brighteners, antifoaming agents, lubricants, preservatives, thickeners, antistatic agents, matting agents, water-soluble polyvalent metal salts, acid bases, pH adjusters such as buffer solutions, antioxidants, surface tension It is a regulator, a non-resistance modifier, a rust inhibitor, an inorganic pigment, and the like.

<Inkjet recording method>
In the ink jet recording method using the ink of the present invention, the ink for ink jet of the present invention is ejected onto a recording medium, and the ink is cured by irradiation with active energy rays.

  Hereinafter, a method for irradiating an inkjet ink with an active energy ray will be described.

[Active energy ray irradiation]
(Active energy rays)
Examples of the active energy rays in the present invention include electron beams, ultraviolet rays, α rays, β rays, γ rays, X-rays, etc., but they are dangerous to the human body and easy to handle. Electron beams and ultraviolet rays that are widely used are preferred. 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.

(Light irradiation conditions after ink landing)
As the irradiation condition of the active energy ray, it is preferable that the active energy ray is irradiated for 0.001 to 1.0 seconds after the ink has landed on the recording medium, and more preferably 0.001 to 0.00. 5 seconds. In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.

(Irradiation method of active energy rays)
As a method for irradiating active energy rays, a basic method is disclosed in Japanese Patent Application Laid-Open No. 60-132767. According to this, the light source is provided on both sides of the head unit, and the head and the light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In US Pat. No. 6,145,979, as an irradiation method, a method using an optical fiber or a method of irradiating a recording unit with ultraviolet rays by applying a collimated light source to a mirror surface provided on the side surface of the head unit is disclosed. . Any of these irradiation methods can be used in the inkjet recording method of the present invention.

  Also preferred is a method in which the irradiation of active energy rays is divided into two stages, and the active energy rays are first irradiated by the above-described method within 0.001 to 2.0 seconds after ink landing, and further the active energy rays are irradiated. It is one of. By dividing the irradiation of the active energy ray into two stages, it is possible to further suppress the shrinkage of the recording material that occurs during ink curing.

(Printer parts)
As a member used in the ink jet printer used in the ink jet recording method of the present invention, in order to prevent irradiation of the head surface due to irregular reflection of actinic rays, for example, ultraviolet rays, a material having a low transmittance or reflectance with respect to active energy rays is preferable. .

  The irradiation unit preferably has a shutter mounted. For example, when ultraviolet rays are used, the ratio of illuminance when opening and closing the shutter is preferably shutter open / shutter close = 10 or more, more preferably 100 or more. Preferably it is 10,000 or more.

"recoding media"
As a recording medium applicable to the ink jet recording method using the ink of the present invention, various types of recording media can be used, and examples thereof include paper, plastic, metal, cloth, and rubber. Of these, paper and plastic films are preferred as ink jet recording media generally used for forming images.

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-weight coated paper having a coating amount per 1 m ^{2 of} about 5 g on one side, a finely coated paper, a mat-like finished mat-coated paper, a dull-like finished dull-coated paper, and a newsprint. 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. Further details are described in detail in the “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 quality, hanging paper, colored paper base, dictionary paper, cream book, white book, cream quality 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, Utrilo 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 NI P (above, made by Daio Paper), Sun Ring, Moon Ring, Cloud Pass, Galaxy, Baiyun, Wyeth, Moon Ring Ace, Baiyun Ace, Cloud Pass Ace (above, Nippon Paper Industries), Taiou, Bright Foam, Bright Nip (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 (Made by 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, Cheri -IV Super (above, made by Maruzumi Paper), SHF (above, made by Toyo Pulp), TRP (above, made by Tokai Pulp), etc.

<Various films>
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. Resin-coated paper that is photographic printing paper or YUPO paper that is synthetic paper can also be used.

<Various inkjet recording media>
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 polymer compounds >>
[Synthesis of Polymer Compound 1]
56 g of glycidyl methacrylate, 48 g of p-hydroxybenzaldehyde, 2 g of pyridine, and 1 g of N-nitroso-phenylhydroxyamine ammonium salt were put in a reaction vessel and stirred in a hot water bath at 80 ° C. for 8 hours.

  Next, 45 g of saponified polyvinyl acetate having a polymerization degree of 300 and a saponification rate of 88% was dispersed in 225 g of ion-exchanged water, and then 4.5 g of phosphoric acid and p- (3-methacryloxy-) obtained by the above reaction were added to this solution. 2-hydroxypropyloxy) benzaldehyde was added to polyvinyl alcohol (polyvinyl acetate saponified product) so as to have a modification rate of 3 mol%, 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 1 hour. 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 0.1 g with respect to 100 g of the above 15% aqueous solution. Dilution was performed to obtain a 10% aqueous solution of polymer compound 1.

[Synthesis of polymer compounds 2 to 4]
In the synthesis of polymer compound 1, the polymerization degree of polyvinyl acetate saponified product, the saponification degree, and the amount of p- (3-methacryloxy-2-hydroxypropyloxy) benzaldehyde charged were appropriately changed, and the polymerization described in Table 1 Polymer compounds 2 to 4 having a degree, a modification rate, and a saponification degree were prepared.

<< Preparation of pigment dispersion >>
[Preparation of yellow pigment dispersion]
The following additives were mixed and dispersed using a sand grinder filled with 0.5 mm zirconia beads at a volume ratio of 50% to prepare a yellow pigment dispersion having a yellow pigment content of 10%. The average particle diameter of yellow pigment particles contained in this yellow pigment dispersion was 112 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

C. I. Pigment Yellow 74 12 parts Joncrill 61 (acrylic styrene resin dispersant, manufactured by Johnson) 3 parts Glycerin 15 parts Ion-exchanged water 70 parts [Preparation of magenta pigment dispersion and cyan pigment dispersion]
In the preparation of the yellow pigment dispersion, C.I. I. Instead of Pigment Yellow 74, the magenta pigment dispersion is C.I. I. Pigment Red 122, the cyan pigment dispersion is C.I. I. A magenta pigment dispersion and a cyan pigment dispersion were prepared in the same manner except that CI Pigment Blue 15: 3 was used. The average particle size of each pigment particle was 81 nm for magenta pigment particles and 95 nm for cyan pigment particles.

[Preparation of black pigment dispersion]
A carbon black self-dispersion cabo-jet 300 manufactured by Cabot was diluted with ion-exchanged water to prepare a black pigment dispersion having a carbon black content of 10%. The average particle diameter of the carbon black particles contained in the obtained black pigment dispersion was 154 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

<Preparation of ink set>
[Preparation of ink set 1]
(Preparation of yellow ink)
10% aqueous solution of polymer compound 1 20 parts Diethylene glycol 10 parts Glycerin 10 parts Triethylene glycol monobutyl ether 10 parts Yellow pigment dispersion 40 parts Surfinol 465 (manufactured by Air Products) 0.5 parts The above components were mixed. Thereafter, ion exchange water was added to make the total amount 100 parts to prepare a yellow ink.

(Preparation of magenta ink, cyan ink, black ink)
In the preparation of the yellow ink, magenta ink, cyan ink, and black ink were prepared in the same manner except that a magenta pigment dispersion, a cyan pigment dispersion, and a black pigment dispersion were used instead of the yellow pigment dispersion. .

[Preparation of ink sets 2 to 6]
Ink sets 2 to 6 were prepared in the same manner as in the preparation of the ink set 1 except that the polymer compound and the addition amount were changed as shown in Table 1. In the ink set having a large amount of polymer compound added, a predetermined amount of water was evaporated and used as a 20% aqueous solution.

[Preparation of ink set 7: comparative example]
Ink set 7 was prepared in the same manner as in preparing ink set 1 except that polymer compound 1 was removed from each ink.

[Preparation of ink set 8: comparative example]
(Preparation of yellow ink)
C. I. Pigment Yellow 74 4 parts Polymer Dispersant (manufactured by Solpers 3200 Avecia) 10 parts Polymerizable monomer: OXT221 (Oxetane Toagosei Co., Ltd.) 80 parts Photoacid generator: CS5102 (Nippon Soda Co., Ltd.) 5 parts Initiator aid: C17001 (Nippon Soda Co., Ltd.) 1 part After mixing each said structural component, the dispersion process was performed and yellow ink was prepared.

(Preparation of magenta ink, cyan ink, black ink)
In the preparation of the yellow ink, C.I. I. Instead of Pigment Yellow 74, magenta ink is C.I. I. Pigment Red 122, cyan ink is C.I. I. Magenta ink, cyan ink, and black ink were prepared in the same manner except that pigment blue 15: 3 and carbon black was used as the black ink.

<< Inkjet image forming method >>
[Inkjet image recording device]
An ink jet image recording apparatus as shown in FIG. 1 equipped with a piezo ink jet nozzle was used.

  The recording head includes an expansion pulse for expanding the volume of the ink chamber by deforming the actuator constituting the ink chamber partition having the configuration described in detail with reference to FIGS. Drive signal generating means for continuously generating a drive signal to be applied to the actuator with a predetermined pause time between the contraction pulse for contracting the volume of the ink chamber, and from the drive signal generating means When the drive signal is generated multiple times, the ink chamber volume is repeatedly expanded and contracted to continuously eject a plurality of ink droplets from the ink nozzle, and the pause time is reduced to reduce crosstalk between adjacent ink chambers. Using the inkjet recording head set to the time, the pause time between the expansion pulse and the contraction pulse is determined by the center of the expansion pulse and its convergence. The time difference from the center of the pulse is set to be equal to the natural vibration period of the ink in the ink chamber, and ink temperature detecting means for detecting the ink temperature in the ink chamber is provided, and the ink temperature is detected by the ink temperature detecting means. By doing so, the pause time between the expansion pulse and the contraction pulse was controlled in accordance with the change in the natural vibration period of the ink depending on the ink temperature. This is called drive control method 1. Further, in place of the drive signal control method described above, image formation was also performed by a method having the drive waveforms shown in FIGS. 11 and 12 (hereinafter referred to as drive control method 2).

[Image printing and evaluation]
Each ink set prepared above was loaded into the ink jet image recording apparatus to form an image, and the obtained images were evaluated as follows.

(Evaluation of character quality)
A piezo-type head having a nozzle diameter of 25 μm, a driving frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi (dpi in the present invention represents the number of dots per 2.54 cm) and a maximum recording density of 720 × 720 dpi is used. Using an on-demand inkjet printer, print 6-point MS Mincho characters with black ink on art paper (NK Art Kanfuji N, manufactured by Oji Paper). A magnifier was used to observe and character quality was evaluated according to the following evaluation criteria.

  In addition, each ink was continuously ejected, and 0.1 seconds after landing, a 120 W / cm metal halide lamp (MAL 400NL, manufactured by Nihon Battery Co., Ltd., power supply power 3 kW · hr) was irradiated.

A: There is no roughness and the dot shape is a perfect circle. O: A slight roughness is observed, but the dot shape is a perfect circle. Δ: A roughness is observed and the dot shape is slightly disturbed, but within the allowable range. Yes x: A level in which roughness is recognized and the dot shape is bad, causing a problem in practical use.

  XX: Both rough and dot shape are extremely bad.

(Evaluation of color bleed resistance)
Using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi using a piezo-type head having a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, art paper (NK Art Kanto N manufactured by Oji Paper) ), A black fine line having a width of 100 μm was printed on a magenta solid, and then visually observed, and color bleed resistance was evaluated according to the following criteria.

  In addition, each ink was continuously ejected, and 0.1 seconds after landing, a 120 W / cm metal halide lamp (MAL 400NL, manufactured by Nihon Battery Co., Ltd., power supply power 3 kW · hr) was irradiated.

◎: The boundary between the fine line and the solid is clear. ○: The boundary is slightly blurred, but there is no problem in practical use. △: The boundary is blurred, but practically acceptable. X: Obvious blurring is observed at the boundary, the line width is about 1.5 times, and this is a quality that is a practical problem. XX: The boundary between the fine line and the solid part is unclear. Quality and extremely low bleed resistance [Glossy]
Using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi, using a piezo head having a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, art paper (NK Art Kongo N, manufactured by Oji Paper) ) Was printed with a solid black of 10 cm × 10 cm, visually observed, and glossiness was evaluated according to the following criteria.

  Each ink was continuously ejected, and 0.1 seconds after landing, a 120 W / cm metal halide lamp (MAL 400NL power supply power 3 kW · hr, manufactured by Nippon Batteries Co., Ltd.) was irradiated.

A: Natural with almost no difference in glossiness between the recording surface and the substrate. ○: The glossiness of the recording surface and the substrate is slightly different but acceptable.

  (Triangle | delta): It can be observed visually that the glossiness of a recording surface and a base | substrate is slightly different, and the glossiness of a recording surface is remarkably higher than a base | substrate.

  X: It can be visually observed that the glossiness of the recording surface and the base is clearly different, and the glossiness of the recording surface is significantly higher than that of the base.

  XX: It can be visually observed that the glossiness of the recording surface and the ground is clearly different, and the glossiness of the recording surface is significantly lower than that of the ground.

(Evaluation of feathering)
Using a piezo-type head with a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle count of 128, and a nozzle density of 180 dpi, using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi, plain paper (First Konica Minolta Business Technology Co., Ltd.) A black thin line having a width of 250 μm and a length of 5 cm was printed on (Class paper), visually observed, and evaluated for feathering according to the following criteria.

  Each ink was continuously ejected, and 0.1 seconds after landing, a 120 W / cm metal halide lamp (MAL 400NL power supply power 3 kW · hr, manufactured by Nippon Batteries Co., Ltd.) was irradiated.

◎: Thin lines are reproduced without blurring due to bleeding ○: Lines are not thickened due to bleeding, but less than 5 spots, ink bleeding along the paper fiber is observed Δ: Lines are thickened due to bleeding No, but less than 10 places, ink bleeding along the paper fiber is observed. X: The line is slightly thickened due to bleeding, and more than 10 ink bleeding along the paper fiber is observed.

XX: Line thickening due to bleeding is intense, and ink bleeding along the paper fiber is observed at 20 or more locations (density measurement)
Using a piezo-type head with a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle count of 128, and a nozzle density of 180 dpi, using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi, plain paper (First Konica Minolta Business Technology Co., Ltd.) A black solid of 10 cm × 10 cm was printed on (Class paper), and the black density was measured with a reflection densitometer of X-Rite, and evaluated according to the following criteria.

  In addition, each ink was continuously ejected, and after landing for 0.1 seconds, 120 W / cm metal halide lamps (MAL 400NL power supply power 3 kW · hr, manufactured by Nihon Battery Co., Ltd.) disposed at both ends of the piezoelectric head were irradiated.

◎: Black density 1.5 or more ○: Black density 1.4 or more, less than 1.5 △: Black density 1.2 or more, less than 1.4 ×: Black density 0.8 or more, less than 1.2 XX: Table 2 shows the results obtained when the black density was less than 0.8.

  As is apparent from the results shown in Table 2, the image recording method using the ink set of the present invention is excellent in character quality and gloss even with a recording medium that does not absorb ink, and excellent in feathering resistance even on plain paper. It can be seen that the image density is obtained.

It is a front view which shows an example of a structure of the principal part of the image recording apparatus used for this invention. It is a longitudinal cross-sectional view which shows an example of a structure of the inkjet head used for this invention. It is a cross-sectional view which shows an example of the part of the inkjet head used for this invention. It is sectional drawing which shows an example of the principle of operation of the inkjet head used for this invention. It is a block diagram which shows an example of a structure of the inkjet head drive device used for this invention. It is a figure which shows an example of the head drive waveform which concerns on this invention. It is a figure which shows another example of the head drive waveform which concerns on this invention. The figure which shows an example of a structure of one drive pulse of the drive waveform in FIG. FIG. 9 is a waveform diagram showing a pressure change in the ink chamber when the drive pulse of FIG. 8 is applied to the ink chamber. It is a figure which shows another example of the drive pulse which concerns on this invention. It is a figure which shows the drive waveform at the time of the conventional 3 division drive. It is a figure which shows the structure of one drive pulse of the drive waveform of FIG.

Explanation of symbols

A image recording apparatus B head carriage C recording head D irradiation means E platen part F guide member H bellows structure P recording material 1, 2 piezoelectric member 4 ink chamber 12 ink discharge port 24 ink drive circuit 25 inkjet head 26 drive waveform control circuit

Claims (7)

A common arrangement in which a plurality of ink chambers provided with ink nozzles for ejecting ink droplets constituting a partition is arranged by an actuator that deforms in response to an applied voltage of an adjacent ink chamber, and ink is supplied to each of the ink chambers. An ink jet recording head provided with an ink chamber;
A predetermined pause is applied between an expansion pulse that expands the volume of the ink chamber by deforming the actuator constituting the ink chamber partition wall and a contraction pulse that contracts the volume of the ink chamber by deforming the actuator. Drive signal generating means for continuously generating a drive signal to be applied to the actuator multiple times,
The volume of the ink chamber is repeatedly expanded and contracted by generating the drive signal from the drive signal generating means a plurality of times, and a plurality of ink droplets are continuously ejected from the ink nozzle, and the pause time is set between adjacent ink chambers. In an image forming method of discharging an inkjet ink that is cured by actinic rays onto a recording material with an inkjet recording head set to a time for reducing the crosstalk of
The inkjet ink contains at least a colorant, water, and a high molecular 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. An image forming method. The pause time between the expansion pulse and the contraction pulse is set so that the time difference between the center of the expansion pulse and the center of the contraction pulse is equal to the natural vibration period of the ink in the ink chamber. Item 4. The image forming method according to Item 1. The image forming method according to claim 1, wherein the inkjet ink contains a polymer compound in an amount of 0.8% by mass to 5.0% by mass with respect to the total mass of the ink. The hydrophilic main chain of the polymer compound contained in the inkjet ink is a saponified product of polyvinyl acetate, having a saponification degree of 77% to 99% and a polymerization degree of 200 to 4000. The image forming method according to claim 1. The polymer compound contained in the inkjet ink has a modification rate of the side chain with respect to the hydrophilic main chain of 0.8 mol% or more and 4 mol% or less. The image forming method according to item. A printed matter produced using the non-absorbent recording material by the image forming method according to claim 1. An image recording apparatus used in the image forming method according to claim 1.

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