JP2007136811A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method whereby an image of a high image quality without any incongruous touch in gloss can be formed by a high efficiency to large-size various recording media. <P>SOLUTION: An inkjet recorder is equipped with a carriage, a carriage driving means, an inkjet head, and an irradiation means with an active energy ray generating part which irradiates active energy rays. A mass of both the carriage and an object carried on the carriage is 1-10 kg. A driving force of the carriage driving means for moving the carriage back and forth is 40 N or smaller. In the inkjet recording method, ink which contains water and at least a polymer compound that has a plurality of side chains in a hydrophilic main chain and is capable of cross-linking between the side chains by irradiation of active energy rays is ejected from the inkjet head by using the inkjet recorder, and image formation is carried out by casting the active energy rays onto a recording medium to which the ink is ejected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording method using an ink jet ink containing an active energy ray-reactive polymer compound.

  The ink jet recording method is an image recording method applicable to on-demand printing on the premise of image formation for each small number of copies, and has been attracting attention in recent years. In the active energy ray curable ink jet system, an ink containing an active energy ray curable compound that is cured by irradiation with active energy rays such as ultraviolet rays (UV) is ejected from an ink jet head and landed on the recording medium. This is an image recording method in which ink is cured by irradiating active energy rays. Since ultraviolet rays (UV) are often used as active energy rays, it is often referred to as a UV inkjet method, and in order to cure ink on the recording medium, recording is possible regardless of the ink absorbency of the recording medium. It has the feature.

  In order to form a high-quality image on a recording medium in the image formation by the UV ink jet method, after the UV ink has landed on the recording medium, the UV ink is promptly irradiated and the UV ink is cured to control the dot diameter. There is a need. Therefore, for example, as in the technique disclosed in Patent Document 1, a light source such as an ultraviolet lamp is mounted on the carriage together with the ink jet head so that the light source moves together with the ink jet head when the ink jet head scans the recording medium. And an optical system such as an optical fiber, a collimator, and a mirror mounted on the carriage as in the technique disclosed in Japanese Patent Application Laid-Open No. H10-228688, and a horizontal direction of the inkjet head from the ultraviolet light source installed at a position away from the inkjet head. A method for inducing ultraviolet rays has been developed so far.

  However, in an inkjet printer that forms an image on a large-sized recording medium such as A0 or B0, when a heavy light source or optical system is mounted on the carriage, the carriage speed decreases, leading to a decrease in productivity. . In addition, when the driving force is increased to move the carriage in order to increase the productivity, it is difficult to control the ink ejection position by stopping the carriage at a predetermined position, resulting in a decrease in image quality. It was happening. As a method for solving this problem, a printer in which carriage mass and driving force are in a specific range is disclosed (see Patent Document 3). As a result, an image can be formed on a large format recording medium with high efficiency.

  However, many of the inks installed in these UV inkjet printers contain a large amount of curable components other than colorants and do not volatilize, so that the recording surface is raised by ink dots, resulting in unnaturalness of image quality, especially gloss. It was generated. 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 substances. .

On the other hand, inks using water-based ultraviolet-ray polymerization monomers containing water as a volatile component have been proposed (see, for example, Patent Document 4), but conventionally known water-based UV curable inks have no sensitivity to active energy rays. In many cases, a large light source having sufficient output and sufficient output is required. Therefore, it has been difficult to achieve both high-efficiency image formation on large-format recording media and high-quality image formation with excellent gloss.
JP-A-60-132767 US Pat. No. 6,145,979 Japanese Patent Laid-Open No. 2003-341021 JP-A-7-224241

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording method capable of forming a high-quality image with no glossy discomfort to various large-sized recording media with high efficiency.

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

1. A carriage that reciprocates on a recording medium, carriage drive means that reciprocates the carriage, an ink jet head that is mounted on the carriage and ejects ink toward the recording medium, and an active energy ray generator And an irradiating means for irradiating an active energy ray toward a recording medium on which ink is ejected,
The combined mass of the carriage and the object mounted on the carriage is 1 to 10 kg,
An ink jet recording apparatus in which a driving force for the carriage driving means to reciprocate the carriage is 40 N or less;
Water and an ink containing at least a polymer compound having a plurality of side chains in a hydrophilic main chain and irradiating with active energy rays can be cross-linked between the side chains are ejected from the ink jet head. An ink jet recording method comprising forming an image by irradiating an active energy ray on a recording medium on which ink is discharged.

  2. 2. The ink jet recording method according to 1, wherein the color of the ink ejected from the ink jet head includes at least four colors of yellow, magenta, cyan, and black.

  3. 3. The ink jet recording method according to 1 or 2, wherein the active energy ray generating unit is mounted on the carriage.

  4). 4. The ink jet recording method according to 3, wherein the active energy ray generating unit includes a fluorescent lamp.

  5. 4. The inkjet recording method according to 3, wherein the active energy ray generating unit includes an LD or an LED.

  6). The ink jet recording method according to any one of claims 1 to 5, wherein the ink is ejected from the ink jet head, the recording medium on which the ink is ejected is irradiated with active energy rays, and then dried.

  7). The inkjet recording method according to any one of 1 to 6, wherein the recording medium is a coated paper for printing.

  8). The inkjet recording method according to any one of 1 to 6, wherein the recording medium is a non-absorbent recording medium.

  According to the present invention, it has been possible to provide an ink jet recording method capable of forming a high-quality image without glossy discomfort with high efficiency on various large-sized recording media.

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

  In the ink jet recording apparatus, the mounting mass, which is the total mass of the carriage and the object mounted on the carriage, is 10 kg or less, so that even when the driving force for moving the carriage is 40 N or less, the initial speed is high. The carriage can be moved and scanning with an inkjet head can be performed with high responsiveness. Therefore, a high-quality image can be formed with high efficiency.

  Even when the mounting mass exceeds 10 kg, it is possible to perform scanning with high responsiveness of the inkjet head by setting the driving force to a value exceeding 40 N. However, in this case, it is difficult to control the speed and position of the inkjet head, and the image quality of the formed image is deteriorated.

  In addition, when the carriage mounting mass exceeds 10 kg and the driving force is 40 N or less, the initial speed of the carriage when the carriage moves at a high speed is lowered, so that the responsiveness at the time of scanning the ink jet head is lowered. As a result, productivity at the time of forming an image at a high speed is lowered. Therefore, when the carriage mounting mass exceeds 10 kg and the driving force is 40 N or less, there arises a problem that the efficiency at the time of image formation is lowered.

  On the other hand, when the carriage mounting mass is less than 1 kg, the number and size of ink jet heads that eject ink onto a recording medium in an ink jet printer that forms an image on a large recording medium such as A0 size or B0 size, for example. Now, the problem of being restricted by mass arises.

  When the number of inkjet heads that can be mounted on the carriage is limited, a color image is formed with a gradation that suits the user's intention, or white ink is ejected as opaque white onto a transparent recording medium so that the image does not transmit. There was a problem that it was difficult to do. Further, when there is a restriction on the size and mass of the ink jet head that can be mounted on the carriage, there is a problem that it is impossible to form an image at a high speed by mounting an ink jet head having a wide print width.

  As a result, by setting the carriage mounting mass to 1 to 10 kg and the carriage driving force to 40 N or less, it is possible to create an inkjet head that can form a high-quality image on a large-sized recording medium with high efficiency. it can.

  Further, by setting the carriage mounting mass to 10 kg or less, it is possible to compactly form each component such as carriage driving means for moving the carriage. Therefore, the inkjet printer can be provided in a compact form that is not limited by the installation location.

  Furthermore, by mounting the active energy ray generating unit on the carriage, the irradiation means can be simplified. This facilitates control of the irradiation means and enhances the durability of the irradiation means. Therefore, an inkjet printer capable of forming an image with high image quality and high efficiency can be easily controlled and provided at low cost.

  By having a fluorescent lamp, LD, and LED as the active energy ray generating unit, the carriage mounting mass can be easily reduced to 10 kg or less. Therefore, an ink jet printer can be manufactured by reducing restrictions on the number, size, and mass of the ink jet head. In addition, the irradiation means can be manufactured at low cost. Accordingly, an inkjet printer capable of forming an image with high image quality and high efficiency can be provided at low cost. Furthermore, since generation of ozone at the time of irradiation with active energy rays can be suppressed, an inkjet printer capable of forming an image with high image quality and high efficiency without causing bad odor can be provided at low cost.

  In the inkjet recording method of the present invention, the inkjet ink discharged onto the recording medium or the intermediate transfer medium is cured by irradiating with active energy rays, and then dried for the purpose of removing unnecessary water-soluble organic solvent. Is preferred.

  The ink drying means is not particularly limited, for example, a method of drying the recording medium or the intermediate transfer medium by contacting the back surface with a heating roller or a flat heater, a means for blowing warm air on the printing surface with a dryer, Alternatively, a method of removing volatile components by a decompression process can be appropriately selected or combined.

[Inkjet recording apparatus, inkjet recording method]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking as an example an ink jet printer that performs image formation by discharging UV ink onto a recording medium.

  In the present specification, the ink jet printer 1 of the type that irradiates UV ink with ultraviolet rays will be described as an example as a preferable example in terms of high curability of the ink and low cost associated with the active energy ray source. The ink jet printer according to the present invention is not limited to one using UV ink.

  In addition, it is possible to use ink having a property of being cured by irradiation with active energy rays such as infrared rays, visible rays, electron beams, and X-rays. Here, the active energy ray is an active energy ray in a broad sense, and does not indicate only that having the ability to ionize air, but includes electromagnetic waves such as infrared rays, visible rays, ultraviolet rays, and electron beams as described above. .

  FIG. 1 is a perspective view schematically showing an ink jet printer 1 according to the present invention. The ink jet printer 1 is a printer for forming a color image on a large recording medium P such as an A0 size or a B0 size, which has extremely low absorbability with respect to UV ink such as a plastic sheet. The ink jet printer 1 forms an image by a capstan system that forms an image on the recording medium P by ejecting UV ink from the ink jet head 2 while moving both the ink jet head 2 and the recording medium P. As shown in FIGS. 1 and 2, the inkjet printer 1 includes an inkjet head 2, a carriage 3, an irradiation unit 4, a guide rail 5, a conveyance unit, a temperature adjustment unit, a carriage driving unit, a control unit (not shown), and the like. Configured.

  A control means (not shown) includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an interface, and the like, and is related to image data to be formed on the recording medium P and the recording medium P. Each component of the inkjet printer 1 is controlled based on data and the like. The guide rail 5 guides the carriage 3 when the carriage 3 moves in the X direction in FIG.

  The carriage 3 is a housing for mounting the inkjet head 2, the irradiation means 4, etc., and is installed on the guide rail 5 in a form that can move in the X direction. The carriage 3 is equipped with the inkjet head 2, the irradiation means 4, the intermediate tank 6, the secondary irradiation means 8, the temperature adjusting means (not shown), the inkjet head drive circuit, and the like.

  The carriage driving means includes an electric motor (not shown) and the like, and applies a driving force for the carriage 3 to reciprocate in the X direction. Here, the condition of the driving force will be described later.

  The inkjet head 2 includes a plurality of ejection units and ejection ports (not shown). The ejection unit includes, for example, a piezo element, and forms ink dots on the recording medium P by ejecting UV ink from an ejection port when voltage is applied from an inkjet head driving circuit. A plurality of ink-jet heads 2 are mounted on the carriage 3 in such a manner that a plurality of ink-jet heads 2 are arranged in a line in the X direction according to the color of ink used in the ink-jet printer 1 and the discharge ports face downward so as to face the recording medium P. Is done.

  Here, FIG. 2 shows an example in which four color inks of magenta (M), cyan (C), yellow (Y), and black (B) are used, and one inkjet head 2 is used for one color. The drawing is done. As described above, by allowing the inkjet printer 1 to eject UV inks of four colors of magenta (M), cyan (C), yellow (Y), and black (K) from the inkjet head 2, the recording medium P is provided. In contrast, a color image can be formed.

  In addition to the above-described inkjet head 2 that ejects the four color inks, the inkjet head 2 that ejects white (W) ink is mounted on the carriage 3 so that the recording medium P made of a transparent film is whitened. The image quality of the image can be improved by preventing the image formed thereafter or before from being transmitted. For example, as shown in FIG. 3A, two white ink-jet heads 2 are arranged such that two color ink Y, M, C, and K ink-jet heads 2 are sandwiched in the X direction. As shown in FIG. 3B, for example, a configuration in which one is installed on the upstream side and the downstream side in the Y direction with respect to the Y, M, C, and K inkjet heads. The two white inkjet heads 2 are not necessarily installed. For example, one of the left and right white inkjet heads 2 in FIG. 3A is omitted, or the Y, M, C, and K inkjet heads 2 are omitted. On the other hand, one white ink jet head 2 may be installed on one of the upstream side or the downstream side in the Y direction.

  Here, the color of the UV ink discharged from the inkjet printer 1 is a design matter. Depending on the user's intention, depending on the characteristics of the image formed on the recording medium P, the ink jet printer 1 may be secondary colors of yellow, magenta, cyan, orange, red, purple, blue in addition to the above-mentioned colors. Further, an ink jet that discharges ink such as green or so-called light color ink having a low color material density may be further mounted. As the light color ink, any of the light color inks of each color may be mounted, but it is preferable to mount at least a color such as light magenta (LM) or light cyan (LC).

  The ink jet head drive circuit generates an applied voltage based on the control of the control unit, and applies a voltage to each ejection portion of the ink jet head 2.

  The irradiating unit 4 includes a generating unit that generates ultraviolet rays, and irradiates the region of the recording medium P where the UV ink is ejected with ultraviolet rays. By irradiating the ink dots on the recording medium P in this way, the surface layer portion of the ink dots is cured to prevent bleeding on the recording medium P and unnecessarily spreading. The irradiating means 4 has a form in which the generating part and other components are combined, and is mounted on the carriage in a form facing the recording medium P.

  As an arrangement form of the irradiation means 4, for example, as shown in FIG. 2A, two ink jet heads 2 are arranged in the X direction with the inkjet head 2 sandwiched in the X direction. As shown in FIG. 2 (b), there is a form in which the inkjet heads 2 are alternately arranged in the X direction. Further, as shown in FIG. 3, when the white inkjet heads 2 are arranged on the upstream side and the downstream side in the Y direction with respect to the inkjet heads 2 of color inks such as Y, M, C, and K, the respective inkjet heads. Further, the irradiation means 4 is installed in a form sandwiching 2.

  Here, it is preferable that the irradiating means 4 is installed so that the time from when the UV ink lands on the recording medium P until it is irradiated with ultraviolet rays is 0.02 to 500 ms. When the time is less than 0.02 ms, the UV ink that has landed on the recording medium P is cured without being sufficiently leveled as ink dots, so the dot diameter becomes extremely small, and the image formed on the recording medium P The image quality of the image becomes lower, and the adhesion of the ink dots to the recording medium P becomes lower, resulting in a problem that the image strength is lowered. On the other hand, when the time exceeds 500 ms, the image quality of the image is deteriorated, for example, by UV ink spreading on the recording medium P.

  The light emission source emits ultraviolet light to irradiate the UV ink on the recording medium P. For example, a mercury lamp, a metal halide lamp, an excimer lamp, a fluorescent lamp, an LD (Laser Diode), an LED (Light Emitting Diode), or the like can be used as the light source applied to the generation unit, and UV ink is quickly cured by irradiation. A light-weight one that generates light of a wavelength is appropriately selected.

  As a light source applied to the generator, for example, a fluorescent lamp is preferable. By applying a fluorescent lamp as the light source, the generating portion can be made light. By making the generating portion light in this way, it becomes easy to suppress the mounting mass of the carriage 3 to 10 kg or less for the purpose as will be described later, and the restrictions on the number, size, and mass of the inkjet head 2 can be reduced. it can. Further, by applying a fluorescent lamp to the light source, the generating part can be manufactured at low cost.

  As a light source other than the fluorescent lamp, LD (Laser Diode) and LED (Light Emitting Diode) are preferable. By applying LD or LED to the generator, the generator can be made light and the same effect as in the case of a fluorescent lamp can be achieved. Moreover, by applying LD or LED, generation of ozone accompanying ultraviolet irradiation can be suppressed and generation of malodor can be prevented.

  Further, in the irradiation unit 4, the method in which the generating unit is mounted on the carriage 3 as in the present embodiment is preferable in terms of durability and controllability of the irradiation unit 4. By providing durability to the irradiation unit 4 in this way, it is possible to reduce labor and cost related to maintenance of the inkjet printer 1. Moreover, the operation of the inkjet printer 1 can be facilitated by improving the controllability of the irradiation means 4.

  Here, the carriage 3 is the mass of the carriage 3 which is a combined mass of components related to UV ink ejection and ultraviolet irradiation, such as the inkjet head 2 mounted on the carriage 3, the irradiation means 4, the intermediate tank 6, and the inkjet head drive circuit. The mounting mass is preferably 1 to 10 kg, and more preferably 1 to 7 kg. The driving force for moving the carriage 3 when scanning with the inkjet head 2 is preferably 40 N or less.

  When the mounting mass is less than 1 kg, the number, size, and mass of the inkjet heads 2 that can be mounted on the carriage 3 are significantly limited in order to reduce the mounting mass.

  By being restricted by the number of ink jet heads 2, in addition to the ink jet heads 2 that eject inks of process colors of Y, M, C, and K, the ink jet head 2 that ejects special colors according to the characteristics of the image is moved to the carriage 3. A clear image that does not transmit by forming a color image with a gradation that fits the user's intention, or by performing whitening with opaque color on a highly transmissive recording medium P. It becomes difficult to form the film.

  In addition, by being restricted by the size and mass of the inkjet head 2, the inkjet head 2 is restricted to have a wide print width and widen the area where ink can be ejected in one scan. This causes a problem that it is difficult to form an image at high speed.

  When the mounted mass exceeds 10 kg and the driving force is 40 N or less, the initial speed of the carriage 3 is remarkably reduced when the carriage 3 is reciprocated in the X direction to scan the inkjet head 2. When the initial speed of the carriage 3 is lowered in this way, the response when scanning the inkjet head 2 at a high speed is delayed, and as a result, the productivity of the image forming work on the recording medium P is lowered, and therefore the efficiency of the image forming work cannot be improved. The problem arises.

  On the other hand, in order to increase the response of the carriage 3, when a high driving force exceeding 40 N is applied to the carriage 3 having a loading mass exceeding 10 kg, it becomes difficult to control the speed and position of the carriage 3 with high accuracy, and recording is performed. Since the accuracy of the position and shape of the ink dots formed on the medium P is lowered, there arises a problem that the image quality of the image formed on the recording medium P is lowered as a result.

  Further, when the mounting mass of the carriage 3 exceeds 10 kg, components such as the inkjet head 2, carriage driving means for reciprocating the carriage 3 during scanning, and a chassis for storing and protecting each component of the inkjet printer 1 Need to be formed into a large volume and mass. For this reason, the entire inkjet printer 1 has a large volume and mass, and there is a problem that the installation location is restricted.

  By setting the mounting mass of the carriage 3 to 10 kg or less, the carriage 3 can be reciprocated in the X direction with high responsiveness even if the driving force is 40 N or less. Therefore, an image can be formed on a large-sized recording medium P with high image quality and high efficiency.

  In order to enable high-productivity image formation on the recording medium P, the weight of each component mounted on the carriage 3 such as the inkjet head 2 and the irradiation unit 4 and the capacity of the intermediate tank 6 can be reduced. By doing so, the mounting mass of the carriage 3 is suppressed to 10 kg or less. The specific means for suppressing the mounting mass of the carriage 3 is a design matter, and is determined as appropriate on the condition that the image quality of the image formed on the recording medium P is not deteriorated.

  The secondary irradiation unit 8 includes a generation unit that emits ultraviolet rays having a wavelength region different from that of the generation unit of the irradiation unit 4, and irradiates ultraviolet rays over the entire width of the recording medium P downstream of the carriage 3 in the Y direction. Installed in a possible form.

  The ink dots that are formed on the recording medium P and whose surface layer portion is cured by being irradiated with ultraviolet rays by the irradiation means 4 are cured to the inside by being irradiated by the secondary irradiation means 8 and are firmly attached to the recording medium P. Glued to.

  As a light source applied to the generating part of the secondary irradiation means 8, a mercury lamp, a metal halide lamp, a flash light source, a fluorescent lamp, or the like is applicable, and a light source that can effectively cure ink dots to the inside is appropriately selected. The

[Ink-jet ink]
Next, the inkjet ink used in the recording method of the present invention will be described. The inkjet ink (hereinafter also simply referred to as ink) used in the recording method of the present invention has a plurality of side chains in the hydrophilic main chain and is capable of cross-linking between the side chains by irradiation with active energy rays. It contains a molecular compound (hereinafter also referred to as a crosslinkable polymer compound).

(Crosslinkable polymer compound)
By applying the crosslinkable polymer compound according to the present invention to ink, sufficient curability is exhibited by irradiation with low energy active energy rays, so that a lighter light source can be mounted on the carriage. This makes it possible to achieve both sufficient curability of ink and carriage mass within a predetermined range. An ink-jet ink can be obtained in which the resolution of the formed image is high, gloss is good, and bleeding between colors is small.

  Next, the crosslinkable polymer compound according to the present invention will be described.

  The hydrophilic main chain of the crosslinkable polymer compound according to the present invention includes saponified polyvinyl acetate, polyvinyl acetal, polyethylene oxide, polyalkylene oxide, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxy And propyl cellulose.

  Among these, when the hydrophilic main chain is a saponified product of polyvinyl acetate, the introduction of the side chain is simplified and the handleability is improved. The degree of polymerization of the main chain is in the range of 200 to 2000, but the degree of polymerization is particularly preferably 200 to 500 from the viewpoint of sufficiently achieving the object effects of the present invention. If the degree of polymerization is 200 or more, a moderate increase in viscosity during the crosslinking reaction can be imparted, and color bleed and beading described later can be sufficiently prevented. If the degree of polymerization is 2000 or less, an increase in viscosity when added to the ink can be suppressed, and good emission stability can be obtained.

  For the side chain, a modifying group such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, and a photodepolymerization type can be introduced. From the viewpoint of reactivity with the color material to be combined, the side chain is preferably nonionic, anionic, or amphoteric (betaine compound). Particularly, when the color material is combined with an anionic dye or an anionic pigment, the side chain is It is preferably nonionic or anionic, and particularly preferably nonionic.

  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 more preferably 1.5 to 3.0 mol% in view of reactivity. To more preferable. If the modification rate of the side chain with respect to the hydrophilic main chain is 0.8 mol% or more, it has sufficient crosslinkability, and the object effect of the present invention can be obtained. On the other hand, if it is 4.0 mol% or less, the crosslinking density is appropriate, so that a flexible image film can be easily obtained and the film strength is particularly good.

  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.

  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.

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

  The amount of the polymer compound added to the ink that has a plurality of side chains in the hydrophilic main chain according to the present invention and can be cross-linked between the side chains by irradiation with active energy rays is 0.8-5. It is preferably 0%.

  If the addition amount is within this range, the crosslinking efficiency is improved, and the ink is ejected from the head and adhered to the base material, and then crosslinked, so that the viscosity of the ink after crosslinking is rapidly increased and the beading resistance and color bleed resistance are increased. Will improve. When the addition amount is less than 0.8%, the objective effect of the present invention obtained due to insufficient crosslinkability is reduced, and when it exceeds 5.0%, the ink viscosity increases and affects intermittent emission stability. Sometimes.

  In the inkjet ink of the present invention, when using a polymer compound having a photopolymerizable modifying group, it is preferable to use a known photopolymerization initiator, and it is particularly preferable to use a water-soluble photopolymerization initiator.

  As a water-soluble photopolymerization initiator applicable to the ink jet ink of the present invention, a compound represented by the following general formula (7) is preferable from the viewpoint of compatibility with a polymer compound and sensitivity.

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

  The photopolymerization initiator is preferably grafted to the side chain with respect to the hydrophilic main chain of the polymer compound according to the present invention.

  Next, other components of the inkjet ink used in the recording method of the present invention will be described.

(Color material)
As the color material used in the ink jet ink used in the recording method of the present invention, a dye or a pigment can be used.

  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.

  Hereinafter, specific examples of the dye applicable to the ink jet ink used in the recording method of the present invention will be listed, but the present invention is not limited to these exemplified dyes.

  Examples of water-soluble dyes that can be used in the present invention include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, and diphenylmethane dyes.

<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.

  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.

  In addition, chelate dyes and azo dyes used for silver dye bleach (silver dye bleaching) photosensitive materials (for example, Cibachrome manufactured by Ciba Geigy) can be used.

  Chelating dyes are described, for example, in British Patent No. 1,077,484. As for azo dyes for silver dye bleaching photosensitive materials, for example, British Patent Nos. 1,039,458, 1,004,957, 1,077,628, U.S. Pat. 612,448.

  Examples of the pigment that can be used in the present invention include conventionally known organic or inorganic pigments. For example, azo pigments such as azo lake pigments, 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. Polycyclic pigments, dye lakes such as basic dye type lakes and acid dye type lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments, and inorganic pigments such as carbon black .

  Hereinafter, specific examples of the pigment applicable to the ink-jet ink of the present invention will be listed, but the present invention is not limited only to these exemplified pigments.

  Examples of magenta or red pigments 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 orange or yellow pigments 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. Pigment yellow 138, C.I. I. Pigment yellow 150, pigment yellow 180, and the like.

  Examples of green or cyan pigments 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 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of the pigment for black include carbon black.

(Self-dispersing pigment)
In the inkjet ink used in the recording method of the present invention, a self-dispersing pigment can be used as a pigment. The self-dispersing pigment refers to a pigment that can be dispersed without a dispersant, and particularly preferably pigment particles having a polar group on the surface.

  Pigment particles having a polar group on the surface are pigments directly modified with a polar group on the surface of the pigment particle, or organic substances having an organic pigment mother nucleus and having a polar group bonded directly or via a joint , Referred to as pigment derivative).

  Examples of the 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 sulfonic acid group.

  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. By making the pigment particle surface described in JP-A-11-323232, JP-A-2000-265094 and the like with an appropriate oxidizing agent, a polar group such as a sulfonic acid group or a salt thereof is formed on at least a part of the pigment surface. The method of introduce | transducing 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 pigment particle surface 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.

  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 (eg, lithium, sodium, potassium, magnesium, calcium, aluminum, nickel, ammonium) and organic salts (eg, triethylammonium, diethylammonium, pyridinium, triethanolammonium, etc.). A counter salt having a monovalent valence is preferable.

(Method for producing pigment dispersion)
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.

(Surfactant applicable to pigment dispersion)
In preparing the pigment dispersion, if necessary, a surfactant or a polymer dispersant may be contained as a pigment dispersant. The type of surfactant and polymer dispersant is not particularly limited. Examples of the surfactant include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, and naphthalene sulfonates. , Alkyl phosphate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide and the like As the polymer dispersant, a water-soluble resin is preferably used from the viewpoint of ejection stability. For example, styrene, a styrene derivative, a vinyl naphthalene derivative, acrylic acid, an acrylic acid derivative, maleic acid, maleic acid. acid Examples include conductors, itaconic acid, itaconic acid derivatives, fumaric acid, block copolymers composed of two or more monomers selected from fumaric acid derivatives, random copolymers, and salts thereof. Styrene-acrylic acid-alkyl acrylate ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid-acrylic acid Examples thereof include an alkyl ester copolymer, a styrene-methacrylic acid copolymer, a styrene-maleic acid half ester copolymer, a vinyl naphthalene-acrylic acid copolymer, and a vinyl naphthalene-maleic acid copolymer.

  The amount of each polymer dispersant added to the total amount of the ink is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass. Two or more of these polymer dispersants can be used in combination.

(Particle size of pigment particles)
The particle size of the pigment particles includes the particle size (primary particle size) obtained by directly observing the particles with an electron microscope, and the dispersed particle size (secondary particle size) using a particle size measuring device utilizing light scattering. There is a viscosity-converted particle size obtained from the intrinsic viscosity.

  The primary particle size of the pigment in the ink of the present invention is preferably 10 to 1000 nm, more preferably 10 to 70 nm, from the viewpoint of light resistance and dispersion stability. If the thickness is smaller than 10 nm, the light resistance is not deteriorated. If the thickness is larger than 100 nm, the head is clogged due to aggregation. Here, in order to obtain the primary particles, the major axis of 1000 pigment particles is measured with a transmission electron microscope, and the average value (number average) can be obtained.

(solvent)
In the inkjet ink used in the recording method of the present invention, it is preferable to use a water-soluble organic solvent. Examples of the water-soluble organic solvent that can be used in the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl). Alcohol), polyhydric alcohols (for example, 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 (for example, ethylene glycol monomethyl ether, ethylene glycol) Ether monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl 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, mole) Phosphorus, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N , N-dimethylacetamide, etc.), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides ( For example, dimethyl sulfoxide etc.), sulfones (for example, sulfolane etc.), urea, acetonitrile, acetone etc. are mentioned. Preferable water-soluble organic solvents include polyhydric alcohols. Furthermore, it is particularly preferable to use a polyhydric alcohol and a polyhydric alcohol ether in combination.

  One or more water-soluble organic solvents may be used in combination. The total amount of the water-soluble organic solvent added to the ink is 5 to 60% by mass, preferably 10 to 35% by mass.

(Inkjet ink set)
The ink set for ink jet used in the recording method of the present invention is composed of ink for three colors or four or more colors.

  As the inks having different hues constituting the ink jet ink set used in the recording method of the present invention, it is preferable to use an ink set composed of yellow, magenta, cyan and black ink jet inks.

  Further, in addition to the four color inks, a light cyan ink, a light magenta ink, a dark yellow ink, and a light black ink (gray ink) may be used. It is also possible to use so-called special color inks such as blue, red, green, orange and violet.

<Dark ink>
In the ink jet ink set used in the recording method of the present invention, an ink jet ink set composed of at least two inks of the same color having different densities in at least one color ink may be used. Furthermore, an ink jet ink set composed of at least two same color inks having different densities in two or more inks may be used. In particular, at least two same color inks having different densities in three or more color inks may be used. From the viewpoint of gradation, it is preferable to use an ink-jet ink set comprising: In particular, it is preferable to use at least two inks having different densities in magenta ink or cyan ink having high human visibility.

  The density ratio of the ink sets for ink jets having different densities may be an arbitrary value. However, in order to perform smooth gradation reproduction, the ratio between the high density ink and the low density ink (the color material density of the low density ink / the high density ink) The color material density of the density ink is preferably between 0.1 and 1.0, more preferably between 0.2 and 0.5, and between 0.25 and 0.4. It is particularly preferred.

<White ink>
In the ink jet ink set used in the recording method of the present invention, a white ink containing a white pigment may be used in addition to the colored pigment. The white pigment used is not particularly limited as long as it makes the ink-jet ink white, and examples thereof include inorganic white pigments, organic white pigments, and white hollow polymer fine particles.

  Examples of inorganic white pigments include sulfates of alkaline earth metals such as barium sulfate, carbonates of alkaline earth metals such as calcium carbonate, silicas such as fine silicate, synthetic silicate, calcium silicate, alumina , Alumina hydrate, titanium oxide, zinc oxide, talc, clay and the like. In particular, since titanium oxide has a high refractive index, it is fine and has high concealability and colorability, and can be preferably used.

  Examples of the organic white pigment include organic compound salts disclosed in JP-A No. 11-129613 and alkylene bismelamine derivatives disclosed in JP-A Nos. 11-14365 and 2001-234093. Specific examples of the white pigment include Shigenox OWP, Shigenox OWPL, Shigenox FWP, Shigenox FWG, Shigenox UL, and Shigenox U (all trade names manufactured by Hackol Chemical Co.).

  Examples of the white hollow polymer fine particles include thermoplastic fine particles made of a substantially organic polymer disclosed in US Pat. No. 4,089,800.

  In the present invention, the white pigment may be used alone or in combination. For the dispersion of the pigment, 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, a paint shaker, or the like can be used. Further, it is possible to add a dispersant when dispersing the pigment.

  A normal dispersant can be used as the dispersant, but a polymer dispersant is preferably used.

  The pigment is preferably dispersed with an average particle diameter of 0.05 to 1.0 μm, more preferably 0.08 to 0.3 μm.

<Colorless ink>
In the inkjet ink set of the present invention, a colorless ink (also referred to as a transparent ink) that does not substantially contain a coloring material can be used in combination.

  In the present invention, the colorless ink containing substantially no color material means a state in which the content of the color material is 0.1% or less with respect to the total ink mass, and preferably contains no color material. is there.

  The component contained in the colorless ink according to the present invention may be either uniformly dissolved or present in a non-uniform dispersion system. Examples of the resin that can be added include an aqueous resin in a dissolved state, an aqueous resin in a dispersed state, an organic solvent based resin in a dissolved state, an organic solvent based resin in a dispersed state, and the like. A resin dispersed in an aqueous system is preferred. Although colorless inks obtained by removing only the color material from the ink-jet ink used can be used, it is preferable to add the following additives in order to add various functions.

  Examples of resins that are dissolved in water include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, color ginnan (κ, ι, λ, etc.), agar, pullulan, water-soluble Polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like can be added.

  As the resin dispersed in an aqueous system, it is particularly preferable to add fine particles of a thermoplastic resin because the glossiness of the image is improved. As the thermoplastic resin fine particles, the thermoplastic resin that can be added to the surface layer of the recording medium or the kind described in the description of the fine particles can be used. In particular, it is preferable to apply those which do not cause thickening or precipitation even when added to the ink. The average particle size of the thermoplastic resin particles is preferably 0.5 μm or less. The fine particles of the thermoplastic resin to be added are preferably those that melt and soften in the range of 0 to 150 ° C.

(Other additives)
In the ink of the present invention, if necessary, various known additives such as ejection stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other performance improvement purposes, for example, , Viscosity modifier, Surface tension modifier, Specific resistance modifier, Film forming agent, Dispersant, Surfactant, Ultraviolet absorber, Antioxidant, Anti-fading agent, Antifungal agent, Rust inhibitor, etc. For example, polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, urea resin, or melamine Organic latex such as resin, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil and other oil droplets, On- or nonionic surfactants, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, JP-A-57-87989, 60-72785, 61-146591, JP-A-1-95091 and JP-A-3-13376, etc., and JP-A-59-42993, 59-52689, 62- 280069, 61-242871, and JP-A-4-219266, etc., optical brighteners, pH adjusters such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. Can be mentioned.

<latex>
In the inkjet ink used in the recording method of the present invention, latex may be added to the ink. Examples thereof include latex such as styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, acrylic ester copolymer, polyurethane, silicon-acrylic copolymer, and acrylic-modified fluorine-fatting. The latex may be obtained by dispersing polymer particles using an emulsifier, or may be dispersed without using an emulsifier. A surfactant is often used as an emulsifier, but a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer in which a solubilizing group is graft-bonded, a single group having a solubilizing group). It is also preferable to use a polymer obtained from a monomer and a monomer having an insoluble part.

  In addition, it is particularly preferable to use soap-free latex in the inkjet ink used in the recording method of the present invention. Soap-free latex is a latex that does not use an emulsifier and a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer in which a solubilizing group is graft-bonded, a solubilizing group) A polymer obtained from a monomer having an insoluble part and a monomer having an insoluble part).

  In recent years, as latex polymer particles, there are also latexes in which core-shell type polymer particles having different compositions at the center and outer edge of the particles are dispersed in addition to the latex in which the polymer particles are uniform throughout. However, this type of latex can also be preferably used.

  In the inkjet ink used in the recording method of the present invention, the average particle size of the polymer particles in the latex is preferably 10 to 300 nm, and more preferably 10 to 100 nm. When the average particle size of the latex exceeds 300 nm, the glossiness of the image is deteriorated, and when it is less than 10 nm, the water resistance and scratch resistance become insufficient. The average particle size of the polymer particles in the latex can be determined by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, or a laser Doppler method.

  In the inkjet ink used in the recording method of the present invention, the latex is preferably added so that the solid content is 0.1 to 20% by mass relative to the total mass of the ink. It is particularly preferable that the content be 0.5 to 10% by mass. If the amount of latex solids added is less than 0.1% by mass, it is difficult to exert a sufficient effect on the weather resistance, and if it exceeds 20% by mass, the ink viscosity increases over time and the ink storage stability is increased. There are many problems that arise.

<Outgoing stabilizer for thermal>
The ink jet ink used in the recording method of the present invention may be used in a thermal ink jet printer. At this time, in order to solve the clogging of the head called kogation, (M ₁ ) ₂ SO ₄ , CH ₃ COO (M ₁ ), Ph-COO (M ₁ ) disclosed in Japanese Patent Laid-Open No. 2001-81379 ), (M ₁ ) NO ₃ , (M ₁ ) Cl, (M ₁ ) Br, (M ₁ ) I, (M ₁ ) ₂ SO ₃ and (M ₁ ) ₂ CO ₃ Good. Here, M ₁ represents an alkali metal, ammonium, or organic ammonium, and Ph represents a phenyl group. Examples of the alkali metal include Li, Na, K, Rb, and Cs. Examples of organic ammonium include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, trihydroxymethylamine, dihydroxymethylamine, monohydroxymethylamine, monoethanolammonium, diethanolammonium, triethanol. Ammonium, N-methylmonoethanolammonium, N-methyldiethanolammonium, monopropanolammonium, dipropanolammonium, tripropanolammonium, etc. are mentioned.

<Crosslinking agent>
The inkjet ink used in the recording method of the present invention may contain a crosslinking agent. Specific examples of the crosslinking agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) , -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum, boric acid or a salt thereof.

<Anti-fading agent>
In the ink jet ink used in the recording method of the present invention, a known anti-fading agent can be used in conventional ink jet inks. This anti-fading agent suppresses fading caused by light irradiation and fading caused by various oxidizing gases such as ozone, active oxygen, NOx, and SOx. Examples of such anti-fading agents include antioxidants described in JP-A-57-74192, JP-A-57-87989, and JP-A-60-72785, and ultraviolet absorbers described in JP-A-57-74193. Hydrazides described in JP-A-61-154989, hindered amine antioxidants described in JP-A-61-146591, nitrogen-containing heterocyclic mercapto compounds described in JP-A-61-177279, The thioether antioxidants described in 1-111577 and 1-36479, the hindered phenol antioxidants having a specific structure described in JP-A-1-36480, JP-A-7-195824 and 8-150773. Ascorbic acids described in No. 7, zinc sulfate described in JP-A-7-149037, thiocyanic acid described in JP-A-7-314882 Thiourea derivatives described in JP-A-7-314883, saccharides described in JP-A-7-276790 and 8-108617, and phosphate-based antioxidants described in JP-A-8-118791. Examples thereof include nitrites, sulfites and thiosulfates described in JP-A-8-300807, and hydroxylamine derivatives described in JP-A-9-267544 as anti-fading agents. Furthermore, polycondensates of dicyandiamide and polyalkylene polyamines described in JP-A No. 2000-266928 and the like are also effective anti-fading agents in inkjet.

<PH buffer agent>
In the inkjet ink used in the recording method of the present invention, a pH buffer agent may be added to the ink. For example, organic acids and inorganic acids. Examples of the organic acid include nonvolatile phthalic acid, terephthalic acid, salicylic acid, benzoic acid, sebacic acid, lauric acid, palmitic acid, ascorbic acid, citric acid, malic acid, lactic acid, succinic acid, succinic acid, and polyacrylic acid. And various organic acids such as benzylic acid.

<Antifoaming agent>
In the inkjet ink used in the recording method of the present invention, an antifoaming agent can be added, and a commercially available product can be used without particular limitation as the antifoaming agent. Examples of such commercially available products include KF96, 66, 69, KS68, 604, 607A, 602, 603, KM73, 73A, 73E, 72, 72A, 72C, 72F, 82F, 70, 71 manufactured by Shin-Etsu Silicone. 75, 80, 83A, 85, 89, 90, 68-1F, 68-2F (trade name), and the like. Although there is no restriction | limiting in particular in the compounding quantity of these compounds, It is preferable to mix | blend 0.001-2 mass% in the ink of this invention. When the compounding amount of the compound is less than 0.001% by mass, bubbles are likely to be generated during ink preparation, and it is difficult to remove small bubbles in the ink, but when the amount exceeds 2% by mass, the generation of bubbles is suppressed. During printing, repellency may occur in the ink and the print quality may be deteriorated.

<Surfactant>
Surfactants preferably used in the inkjet ink used in the recording method of the present invention include alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, and polyoxyalkylene alkyls. Anionic surfactants such as ether phosphates and fatty acid salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers Agents, glycerin esters, sorbitan esters, polyoxyethylene fatty acid amides, active agents such as amine oxides, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

(Preparation of ink)
There is no particular limitation on the preparation of the ink jet ink used in the recording method of the present invention, but when preparing an ink containing a dispersion such as a pigment, a disperse dye, inorganic fine particles, resin fine particles, agglomeration in the preparation process, It is preferable to prepare the ink so that settling does not occur. If necessary, a preparation method such as adjusting the order of addition of the dispersion, solvent, water, photosensitive resin and other additives, and the addition rate can be taken. In addition, for the purpose of stabilizing dispersion and redispersing the agglomeration generated during the blending of the ink during or after blending, a dispersion process using a bead mill or ultrasonic waves, a heat treatment, or the like may be performed.

(Ink physical properties)
<viscosity>
The viscosity of the inkjet ink used in the recording method of the present invention is not particularly limited, but is preferably 2 to 100 mPa · s. Moreover, it is preferable that the viscosity of the inkjet ink of the present invention has no speed dependency.

  In the inkjet ink of the present invention, the viscosity at 25 ° C. is preferably 15 mPa · s or less, more preferably 5 to 15 mPa · s.

  The ink viscosity (mPa · s) in the present invention is not particularly limited as long as it is tested with a standard solution for calibration of a viscometer specified in JIS Z 8809, and is measured at 25 ° C. according to a known method. As the viscosity measuring device, a rotary, vibration or capillary type viscometer can be used, for example, a Saybolt viscometer, a Redwood viscometer, etc., for example, a cone plate type manufactured by Tokimec E type viscometer, Toki Sangyo E Type Viscometer (rotary viscometer), Tokyo Keiki B type viscometer BL, Yamaichi Denki FVM-80A, Nametor Kogyo Viscoliner VISCO MATE MODEL VM-1A, DD-1 manufactured by Denki Co., Ltd. can be exemplified.

<surface tension>
Moreover, in the inkjet ink used in the recording method of the present invention, the surface tension is preferably 40 mN / m or less, more preferably 20 to 35 mN / m.

  The surface tension (mN / m) of the ink referred to in the present invention is a value obtained by measuring the surface tension measured at 25 ° C., and the measurement method is described in general interface chemistry, colloid chemistry reference books, etc. For example, New Experimental Chemistry Course Volume 18 (Interface and Colloid), The Chemical Society of Japan, published by Maruzen Co., Ltd. 68-117 can be referred to. Specifically, it can be determined using a ring method (Dunoi method) or a platinum plate method (Wilhelmy method), but in the present invention, it is represented by a surface tension value (mPa · s) measured by the platinum plate method. For example, it can be measured using a surface tension meter CBVP-Z manufactured by Kyowa Interface Science.

<Electrical conductivity>
In the inkjet ink used in the recording method of the present invention, from the viewpoint of ink storage stability, the electrical conductivity is preferably 1 to 500 mS / m, more preferably 1 to 200 mS / m, and still more preferably. 10 to 100 mS / m. When the electric conductivity of the ink exceeds 500 mS / m, an emission defect due to deposition of a coloring material or the like occurs. Moreover, if it is 1 ms / m or less, sufficient electrostatic repulsion for allowing the dispersion to exist stably cannot be obtained, and it will also aggregate. Therefore, the dispersion can be stably present by setting the electric conductivity to 1 to 500 mS / m.

  In the ink according to the present invention, there is no particular limitation as a means for achieving a desired electric conductivity. In the present invention, a pigment is used as a coloring material, and a polymer compound (polymer dispersing agent) is used as a pigment dispersant. The method used or a method using an electrical conductivity modifier, for example, an inorganic salt such as potassium chloride, ammonium chloride, sodium sulfate, sodium nitrate, or sodium chloride, or an aqueous amine such as triethanolamine is appropriately selected or combined. Can be achieved.

  The measurement of the electrical conductivity of the ink in the present invention should be easily performed according to the method described in JIS K 0400-13-10 (1999) or the method disclosed in JP-A-61-61164. Can do.

<Ion concentration adjustment>
In preparing the inkjet ink used in the recording method of the present invention, it is preferable to adjust the ion concentration as appropriate.

  An aqueous dye solution having a predetermined concentration is measured by ICP-AES, and the ion concentration of the ink state is calculated in terms of the dye concentration used in the ink. By using distilled water or ion-exchanged water, the ion concentration at the time of ink formation can be estimated.

  Next, an ink is prepared by adding other additives and the like, and the ion concentration in the ink is measured by ICPAES. When the target ion concentration is exceeded, the ion concentration can be lowered by passing the aqueous dye solution through an ion exchange resin. Ion exchange can be performed a plurality of times to further reduce the ion concentration. If the desired ion concentration is not reached, the additives other than the dye are also subjected to treatment such as ion exchange. Moreover, you may add processes, such as filtration by an activated carbon process or an ultrafiltration membrane, as needed.

<Deaeration treatment>
The dissolved oxygen concentration in the inkjet ink used in the recording method of the present invention is preferably 2 ppm or less, more preferably 1 ppm or less. If the dissolved oxygen concentration in the ink-jet ink exceeds 2 ppm, cavitation occurs when ink is ejected, and emission defects are likely to occur.

  The method for adjusting the dissolved oxygen concentration is not particularly limited. However, as described in JP-A-11-209670, a method for degassing an inkjet ink under reduced pressure, a method for degassing by irradiating ultrasonic waves, and a method for degassing. Examples include a degassing method using a hollow fiber membrane. In particular, degassing with a degassing hollow fiber membrane is preferred.

〔recoding media〕
Next, the recording medium used in the present invention will be described.

  As the recording medium applicable in the ink jet recording method of the present invention, various papers, various films, various cloths, various woods, various ink jet recording media, and the like can be used. The recording medium is preferably a recording medium.

(Coated paper for printing)
Coated paper for printing is coated paper often used in printing. Generally, high-quality paper or medium-quality paper is used as the base paper, and after applying a pigment such as clay on the surface of the paper, smoothness is improved. Therefore, it is produced by applying a calendar process. Such processing improves whiteness, smoothness, printing ink acceptability, halftone dot reproducibility, printing gloss, printing opacity, and the like. The paper is classified into art paper, coated paper, lightweight coated paper, etc., depending on the coating amount, and is classified into glossy, dull, matte, etc., depending on the gloss of the paper.

Art paper is coated paper having a coating amount of about 20 g / m ^{2 on} one side, and is generally prepared by applying a pigment to the paper surface and then applying a calendar treatment. There are special art, medium art, matte (matte) art, single art (single side coating), double art (double side coating), and more specifically, OK Kanto N, Satin Kanto N, SA Kanou, Ultra Satin Kinto N, OK Ultra Aqua Satin, OK Kanto One Side, N Art Post, NK Special Sided Art, Thunderbird Super Art N, Thunderbird Super Art MN, Thunderbird Art N, Thunderbird Dull Art N, Hi McKinley Art, Hi McKinley Mat, High McKinley Pure Dull Art, Hi McKinley Super Dal, Hi McKinley Mat Elegance, Hi McKinley Deep Mat, etc.

The coated paper is a coated paper having a coating amount of about 10 g / m ^{2 on} one side, and is generally produced by processing with a coating apparatus provided in the middle of the paper machine. The coating amount is smaller than that of art paper, and the smoothness is slightly reduced, but the advantages are low cost and light weight. There is also a type of coated paper with a smaller coating amount, such as a light-weight coat and a finely coated paper. Specific examples of these coated papers include POD gloss coat, OK top coat +, OK top coat S, aurora coat, mu coat, mu white, thunderbird coat N, utrilo coat, pearl coat, white pearl coat, POD mat coat, New Age, New Age W, OK top coat mat N, OK royal coat, OK top coat dull, Z coat, Silver diamond, Ulite, Neptune, Mu mat, White mu mat, Thunderbird mat coat N, Utrilogros mat, New V mat, white new V mat, etc. are mentioned.

(Non-absorbent recording medium)
A non-absorbent recording medium is a medium in which the surface layer on which ink lands is in a substantially homogeneous state with no gap for absorbing ink. Here, voids that absorb ink include, for example, voids between fibers that form paper, gaps between polymers that form a resin that swells by absorbing ink, fillers, and resin particles. For example, voids in the formed layer.

  A recording medium having a void that absorbs ink in the surface layer is expensive and has a problem of low durability and weather resistance. On the other hand, there are many recording media made of non-ink-absorbing materials that are inexpensive and have a structure resistance and durability. Therefore, by allowing the inkjet printer according to the present invention to form an image on a non-ink-absorbing material, a printed matter suitable for an advertising medium, a packaging material, or the like can be produced at a low cost.

  Specific examples of non-ink-absorbing materials that do not have ink-absorbing voids in the surface layer include metals, glass, plastics that do not have an absorbing layer, and paper that has a resin-coated surface. Among the above materials, a paper coated with a resin on the surface and a plastic film for soft packaging materials are preferable because they are inexpensive, durable, and weather resistant, and can be easily applied to advertising media and packaging materials.

  Specific materials for plastic films for flexible packaging materials include polyester, polyolefin, polyamide, polyesteramide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-p-phenylene sulfide, polyether ester, polyvinyl chloride, Poly (meth) acrylic acid ester, polyethylene, polypropylene, and nylon are preferable, and copolymers, mixtures of the above-described materials, and materials formed by crosslinking the above-described polymers with each other are also applicable. Among the above materials, polyethylene terephthalate, polystyrene, polypropylene, and nylon are preferable in terms of transparency, dimensional stability, rigidity, environmental load, and cost.

  The plastic film having a thickness of 2 to 100 μm can be applied as a packaging material. The plastic film preferably has a thickness of 6 to 80 μm. When the thickness of the plastic film is less than 2 μm, there is a problem that the strength is low and the content is easily broken and the contents cannot be stored and protected. Moreover, when the said thickness exceeds 100 micrometers, the facility for packaging a content will become a special thing, and the problem that cost becomes high will arise. The plastic film preferably has a thickness of 10 to 70 μm.

(Image formation)
Next, a procedure for forming an image on a recording medium using an ink jet printer will be described with reference to FIG.

  Image formation proceeds by the ejection of UV ink by the inkjet head 2. At this time, the inkjet head 2 scans the recording medium P in the X direction by the reciprocating movement of the carriage 3 by the operation of the carriage driving means. In parallel with this scanning, UV ink is discharged from the discharge port of the inkjet head 2. The discharge of the UV ink is performed by applying a voltage from the inkjet head drive circuit to the discharge unit under the control of the control unit based on the image data formed on the recording medium P.

  The UV ink ejected from the inkjet head 2 is landed sequentially on the recording medium P to form ink dots. The ink dots spread on the recording medium P by leveling.

  Subsequent to the discharge of the UV ink from the inkjet head 2, the region of the recording medium P where the ink dots are formed is irradiated with ultraviolet rays.

  Scanning of the inkjet head 2 is performed in parallel with the discharge of UV ink. Therefore, UV ink is ejected from the inkjet head 2, and the UV ink is landed on the recording medium P to form ink dots. After the ink dots are appropriately spread by leveling, the irradiation means 4 moves immediately above the ink dots. It will be irradiated with ultraviolet rays. Thus, the ink dots are cured at the surface layer so as not to bleed.

  After the inkjet head 2 scans in the X direction over the entire width of the recording medium P and discharges UV ink, the recording medium P is appropriately conveyed in the Y direction by the conveying means. After the recording medium P is transported in the Y direction, the inkjet head 2 is further scanned and UV ink is ejected, and the ink dots formed by the ejection are irradiated by the irradiating means 4 and cured on the surface layer portion.

  By the conveyance in the Y direction by the conveyance means, the area where the ink dots are formed on the recording medium P moves to the area directly below the secondary irradiation means 8. When the secondary irradiating means 8 is irradiated with ultraviolet rays, the ink dots are cured to the inside and firmly adhered to the recording medium P.

  By repeating the above operation, an image is formed on the recording medium P. Here, when the recording medium P is a transparent material, the white ink is applied as opaque white to the area where the image of the recording medium P is formed by performing the above-described operation on the white ink, and then whitening is performed. The image formation is performed by repeating the above-described operation for color inks including process colors such as Y, M, C, and K. Further, when the recording medium P is made of a material that does not have transparency, image formation is performed by repeating the above operation only for the color ink.

  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.

Example << Synthesis of Crosslinkable Polymer Compound >>
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, respectively, and stirred in a hot water bath at 80 ° C. for 8 hours.

  Next, 45 g of polyvinyl acetate saponified product having a degree of polymerization of 300 and a saponification rate of 98% was dispersed in 225 g of ion-exchanged water, and then 4.5 g of phosphoric acid was added to this solution to obtain p- (3 -Methacryloxy-2-hydroxypropyloxy) benzaldehyde was added to polyvinyl alcohol so that the modification rate was 3.5 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. The ion exchange resin was filtered and then diluted with pure water to obtain a 15% by mass aqueous solution of the crosslinkable polymer compound 3. The crosslinkable polymer compound 3 has a plurality of side chains in a saponified product of polyvinyl acetate, which is a hydrophilic main chain, and can be cross-linked between the side chains by irradiating active energy rays. It is.

<Preparation of ink set>
[Preparation of ink set 1]
Ink set 1 composed of yellow ink 1, magenta ink 1, cyan ink 1 and black ink 1 was prepared according to the following method.

(Preparation of yellow ink 1)
The following compositions were sequentially mixed, dispersed using a bead mill, and then filtered through a # 3000 metal mesh filter to prepare yellow ink 1.

Crosslinkable polymer compound 3 2 parts as solid content Propylene glycol 10 parts 2-Pyrrolidinone 10 parts Activator: BYK347 (by Big Chemie) 0.05 part Polymerization initiator: Irgacure 2959 1 part Pigment: Cab-O-Jet270 (Cabot) (Yellow self-dispersing pigment)
3 parts as solid content Antifungal agent: Proxel GXL (manufactured by Avicia) 0.2 parts Ion exchange water was added to each of the above compositions to finish 100 parts.

(Preparation of magenta ink 1, cyan ink 1, black ink 1)
In the preparation of the yellow ink 1, the pigment was replaced with Cab-O-Jet 270, Cab-O-Jet 260 (magenta self-dispersing pigment manufactured by Cabot), Cab-O-Jet 250 (cyan self-dispersing pigment manufactured by Cabot), respectively. Magenta ink 1, cyan ink 1, and black ink 1 were prepared in the same manner except that Cab-O-Jet 300 (black self-dispersing pigment manufactured by Cabot) was used.

[Preparation of ink set 2]
Ink set 2 (comparative example) comprising yellow ink 2, magenta ink 2, cyan ink 2 and black ink 2 was prepared according to the following method.

(Preparation of yellow ink 2)
The following compositions were sequentially mixed and dispersed using a bead mill, and then pre-dispersed for 1 hour using a dissolver. Further, the mixture was kneaded using a bead mill and filtered through a # 3000 metal mesh filter to prepare yellow ink 2.

Active energy ray reactive compound: A-TMPT-3EO 5 parts Ethylene glycol 15 parts 1,2-hexanediol 8 parts Activator: Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part Polymerization initiator: Irgacure 2959 0.5 Part Pigment: C.I. I. Pigment Yellow 74 3 parts Pigment dispersant: Solsperse 20000 (manufactured by Avicia) 1 part Antifungal agent: Proxel GXL (manufactured by Abyssia) 0.2 part Ion exchange water was added to each of the above compositions to finish 100 parts.

  In the preparation of the yellow ink 2, the pigment is C.I. I. In place of Pigment Yellow 74, C.I. I. Pigment red 122, C.I. I. Magenta ink 2, cyan ink 2, and black ink 2 were prepared in the same manner except that CI pigment blue 15: 3 and carbon black were used.

[Preparation of ink set 3]
A yellow pigment dispersion Y1, a magenta pigment dispersion M1, a cyan pigment dispersion C1 and a black pigment dispersion K1 were obtained by blending a pigment, a dispersant and the like with the following composition.

  First, a small amount of phenoxyethyl acrylate was pre-dispersed with a pressure kneader together with a predetermined amount of pigment, dispersant, and acrylic resin, and the pigment surface was sufficiently wetted, and then kneaded with three roll mills. Subsequently, the remaining phenoxyethyl acrylate was added and dispersed by a bead mill.

<Yellow pigment dispersion Y1>
Pigment Yellow 180 (pigment) 15.0 parts by weight Nonionic dispersant (dispersant) 1.5 parts by weight Phenoxyethyl acrylate (polymerizable composition) 80.0 parts by weight Acrylic resin (acid value 0) 3.5 parts by weight <Magenta pigment dispersion M1>
Pigment Violet 19 (pigment) 15.0 parts by weight Nonionic dispersant (dispersant) 1.5 parts by weight Phenoxyethyl acrylate (polymerizable composition) 80.0 parts by weight Acrylic resin (acid value 0) 3.5 parts by weight Part <Cyan pigment dispersion C1>
Pigment Blue 15: 3 (pigment) 15.0 parts by weight Nonionic dispersant (dispersant) 1.5 parts by weight Phenoxyethyl acrylate (polymerizable composition) 80.0 parts by weight Acrylic resin (acid value 0) 3. 5 parts by mass <Black pigment dispersion M1>
Pigment Violet 19 (pigment) 15.0 parts by weight Nonionic dispersant (dispersant) 1.5 parts by weight Phenoxyethyl acrylate (polymerizable composition) 80.0 parts by weight Acrylic resin (acid value 0) 3.5 parts by weight Part Using the above pigment dispersions Y1, M1, C1, and K1, blending as shown in Table 1 to prepare ink set 3 composed of yellow ink 3, magenta ink 3, cyan ink 3, and black ink 3 did. First, all the materials shown in Table 1 except for the pigment dispersion were blended, and after confirming that the ink was sufficiently dissolved, the above-mentioned pigment dispersion was added little by little, and then fully dissolved using a dissolver. This was done by stirring. After blending, pre-filtration was performed with a 10 μm filter, followed by filtration with a 0.8 μm filter.

  Here, the abbreviations shown in Table 1 are as follows.

DPCA60: KAYARAD DPCA (caprolactam-modified dipentaerythritol hexaacrylate) manufactured by Nippon Kayaku Co., Ltd.
TEGDA: Osaka Organic Chemical Co., Ltd., Biscoat # 335HP (tetraethylene glycol diacrylate)
PO-A: Light acrylate PO-A (phenoxyethyl acrylate) manufactured by Kyoeisha Chemical Co., Ltd.
I369: Initiator, manufactured by Ciba Specialty Chemical, Irgacure 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1)
<Image formation>
An image was formed on a recording medium by an ink jet printer using the ink set. Mirror-coated platinum (manufactured by Oji Paper Co., Ltd.), which is a cast-coated paper for printing with little ink absorbability, was used as a recording medium on which image formation was performed.

  The carriage driving means for generating the driving force for moving the carriage 3 in FIG. 1 is UGFED-B5L (rated voltage: DC 30 V, rated torque: 0.0529 N · m, rated rotation) manufactured by YE Drive. Number: 4200 rpm, rated output: 23 W, rated current: 1.1 A, stationary torque: 0.392 N · m or more, no-load rotation speed: 4635 rpm ± 10%) was used as a power source.

  As the inkjet head 2, a piezo-type inkjet head having a nozzle diameter of 23 μm and 128 nozzles was used. Vero85 (manufactured by Integrated Technology) was used for the generating part of the irradiation means 4, and an ultra-small cold cathode black lamp TBB30 series (manufactured by Highbeck) was used for the generating part of the secondary irradiation means 8.

  The ink supply system for supplying UV ink to the inkjet head 2 includes a supply pipe and a pipe with a filter in addition to the main tank and the intermediate tank 6, and shields light from the intermediate tank 6 to the inkjet head 2.

The amount of ink ejected at one time was set to 7 pl. The drive frequency was set to 10 kHz so that an image could be formed at a resolution of 720 × 720 dpi (dpi represents the number of dots per 2.54 cm) when evaluating image quality and dot quality, which will be described later. In the evaluation of high-speed printing suitability described later, the frequency was set to 40 kHz so that an image can be formed with a resolution of 360 × 360 dpi. Further, the illuminance of ultraviolet rays irradiated from the irradiation unit 4 and the secondary irradiation unit 8 was adjusted to be 30 mW / cm ² in the recording medium P.

  For the above-described inkjet printer 1, recording medium P, and ink set 1, image formation in each example and comparative example was performed under the following conditions.

  In inkjet recording method 1, image formation was performed using one inkjet head 2 for each of the four colors Y, M, C, and K. Irradiation means 4 uses Vzero 85 as a generating part, and was alternately arranged with inkjet head 2 as shown in FIG.

  In the inkjet recording method 2, the same conditions as in the inkjet recording method 1 were used except that a polyethylene terephthalate film was used as the recording medium.

  In the ink jet recording method 3, the conditions were the same as those of the ink jet recording method 1, except that an LED was used as the generating unit of the irradiation unit 4 and SA Kanto + (Oji Paper) was used as the recording medium.

  In the inkjet recording method 4, Vzero85 (manufactured by Integrated Technology) was used for the generating part of the irradiation unit 4, and the same conditions as in Example 1 were used except for the type of light source used for the generating part. In the ink jet recording methods 5 and 6, the same conditions as those of the ink jet recording method 1 were adopted except that the ink set to be mounted was changed to the ink sets 2 and 3.

  Table 1 shows the carriage masses of the carriage 3 under the conditions of the inkjet recording methods 1 to 6. Under these conditions, the carriage 3 was reciprocated by applying a driving force of 30 N to the carriage 3, and the image quality of the image formed by performing image formation on the recording medium P was evaluated.

  Furthermore, image formation was performed on the recording medium P by setting the driving force of the carriage 3 in the inkjet recording method 4 to 45 N, and the image quality and the like of the formed image were evaluated. This was designated as inkjet recording method 7.

<Image formation>
The images created by the inkjet recording methods 1 to 7 were evaluated.

(image quality)
Visual evaluation was performed according to the following criteria.

○: There is almost no unevenness in the image and the image quality is good. ×: White spots and unevenness are seen in the image (high-speed printability)
The resolution is set to 360 × 360 dpi, the drive frequency is set to 40 kHz, and printing is performed by changing the main scanning speed, which is the speed at which the inkjet head 2 scans, to 1.0 m / s, 1.5 m / s, and 2.0 m / s. The productivity of image formation was evaluated.

A: Stable printing possible even at a main scanning speed of 2.0 m / s B: Stable printing possible even at a main scanning speed of 1.5 m / s or more X: Printing is unstable at a main scanning speed of 1.0 m / s (Ink Curability)
As an evaluation of ink curability, bleeding between different colors was visually evaluated according to the following criteria.

○: Bleeding between colors hardly occurs ×: Bleeding between colors occurs (image gloss)
Visual evaluation was performed according to the following criteria.

○: An image with a little glossiness between the printed part and the non-printed part and a good gloss feeling. X: An image with a feeling of strangeness between the image part and the non-image part and an inferior glossy result Table 2 shows the evaluation results.

  From Table 2, it can be seen that, in the ink jet recording methods 1 to 3 of the present invention, a high-quality image without glossy discomfort can be formed with high efficiency on a large recording medium.

  As shown in Table 2, in the ink jet recording methods 1 to 3, an image can be formed with a stable image quality with extremely little unevenness by setting the mounting mass of the carriage 3 to 1 to 10 kg. Further, by setting the driving force for reciprocating the carriage 3 to 30 N, even when the main scanning speed is set to 1.5 m / s or more, image formation can be performed efficiently with high productivity. Furthermore, by using the ink set 1 containing a high molecular compound that can be cross-linked by active energy rays, the ink exhibits excellent curability and an image with excellent gloss can be obtained in the ink jet apparatus having the above-described configuration. It was.

  As described above, the mounting mass, which is the mass of the ink jet head 2 and the irradiation means 4 on which the components relating to the ejection of the UV ink and the ultraviolet irradiation are mounted, is 10 kg or less, and the driving force for moving the carriage 3 is 40 N. Thus, even when the initial speed when the carriage 3 moves is increased and the inkjet head 2 is scanned with high responsiveness, the speed and position of the inkjet head 2 are controlled with high accuracy, and a large-sized recording medium An image can be formed on P. Therefore, an image can be formed on a large recording medium P with high image quality and high efficiency.

  Further, by setting the mounting mass of the carriage 3 to 10 kg or less, other components such as the carriage driving means can be made compact. Therefore, the inkjet printer 1 can be made compact without being restricted by the installation location.

  Further, by setting the total mass of the carriage 3 to 1 kg or more, the inkjet head 2 that discharges the special color ink can be mounted on the carriage 3 in addition to the inkjet head 2 that discharges the process color ink. Therefore, it is possible to form a color image with a gradation that matches the user's intention, or to white the transparent recording medium P. It is also possible to perform image formation at high speed by applying the inkjet head 2 having a wide printing width.

  Further, the inkjet printer 1 according to the present invention can form an image on a large recording medium P with high image quality and high efficiency. By providing images with high image quality and high efficiency in an inexpensive material having weather resistance and durability, it is possible to provide inexpensive prints with weather resistance and durability with high image quality and high efficiency. be able to.

  In the inkjet printer 1 according to the present invention, the means for setting the carriage mass of the carriage 3 to 1 to 10 kg does not necessarily reduce the weight of the light source applied to the generator as in the above-described embodiment.

  In order to set the mounting mass within the above range, for example, components such as the intermediate tank 6 and the ink jet head driving circuit can be reduced in weight or installed outside the carriage 3.

  Alternatively, the generating unit of the irradiation unit 4 may be installed apart from the carriage 3 without being mounted on the carriage 3. In this case, the carriage 3 is equipped with an optical system such as a mirror and a prism, and an active energy ray such as ultraviolet rays generated at the generating portion is guided onto the recording medium P by this optical system, so that the ink dot can be quickly formed after the ink dots are formed. The ink dots may be irradiated with active energy rays. Further, the irradiation means 4 may be installed in a form capable of irradiating active energy rays over the entire width of the recording medium P immediately above the area where the carriage 3 reciprocates.

  Means for setting the carriage mass of the carriage 3 to 1 to 10 kg is a design matter, and is appropriately determined on the condition that an image can be formed on the recording medium P with high image quality and high efficiency.

  The ink jet printer and the image recording method according to the present invention are not limited to those described above. The active energy rays irradiated by scanning with respect to the ink dots are not necessarily ultraviolet rays. In the inkjet printer 1 and the image recording method according to the present invention, the ink dots may be cured using active energy rays such as visible light, infrared rays, electron beams, and X-rays.

  For example, the ink jet printer and the image recording method according to the present invention may be configured to irradiate ink dots on a recording medium with an electron beam. By applying an electron beam as the active energy ray, the ink dot can be quickly cured even when an inexpensive ink that does not contain a polymerization initiator is applied. Therefore, a high-quality image can be formed on the recording medium P with high productivity and at low cost.

  In addition, when an electron beam is applied as the active energy ray, the generation of heat due to the generation and irradiation is less than that in the case of ultraviolet rays, so that the cost required for cooling the inkjet printer 1 can be reduced.

  Examples of the type of irradiation means that irradiates an electron beam as an active energy ray include “Development of UV / EB Curing Technology” (edited by Radtech Research Group, 1999 edition, page 95) and “Painting Technology” October 2001 issue 90 A known document such as a page is applicable.

  As an electron accelerator for electron beam irradiation applied to the irradiation means, a curtain beam type is preferable in that a large output can be realized at a relatively low cost.

  Moreover, it is preferable that the acceleration voltage in the case of electron beam irradiation is 100-300 kV. When the acceleration voltage is less than 100 kV, there is a problem that sufficient energy is not applied to the electron beam applied to the ink dots, and the ink dots cannot be sufficiently cured. On the other hand, when the acceleration voltage exceeds 300 kV, there arises a problem that the costs associated with the irradiation and production of the electron beam produced and maintained by the irradiation means increase.

  Moreover, it is preferable that the absorbed dose which an ink dot absorbs an electron beam is 0.5-10 Mrad. When the absorbed dose is less than 0.5 Mrad, the ink dots are not sufficiently cured on the recording medium P, and there arises a problem that the ink is blurred or the strength of the image is lowered. Further, when the absorbed dose exceeds 10 Mrad, there arises a problem that the recording medium P deteriorates.

  In addition, as other types of active energy rays, infrared rays having a wavelength of 800 nm or more may be applied as energy rays. In this case, an energy ray curable ink having a property of being cured by a thermal reaction can be applied. As the energy ray curable ink, a peroxide compound such as benzoyl peroxide as a thermal reaction initiator, a diazo compound (thermal radical generator) such as AIBN, and a compound common to the photoacid generator exemplified in the above-described examples are used. Applicable ones can be applied. In addition, a substance that has a strong tendency to absorb near-infrared rays and radiate heat, such as cyanine dyes, squarylium dyes, polymethine dyes, carbon black, and titanium black, may be used as the initiation assistant.

  In addition, the ink jet printer according to the present invention does not necessarily include secondary irradiation means. When the ink dots are cured only by irradiation of the irradiation means, the ink dots have sufficient strength and are cured, and the image is given sufficiently high strength by adhering to the recording medium with high adhesiveness. In this case, the ink jet printer may be configured not to include the secondary irradiation unit.

1 is a perspective view showing an outline of an ink jet printer according to the present invention. It is a principal part perspective view which shows the example of arrangement | positioning of the component mounted in the carriage applied to this invention. It is a principal part top view which shows the example of arrangement | positioning of the inkjet head applied to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Inkjet head 3 Carriage 4 Irradiation means 6 Intermediate tank 8 Secondary irradiation means P Recording medium

Claims (8)

A carriage that reciprocates on a recording medium, carriage drive means that reciprocates the carriage, an ink jet head that is mounted on the carriage and ejects ink toward the recording medium, and an active energy ray generator And an irradiating means for irradiating an active energy ray toward a recording medium on which ink is ejected,
The combined mass of the carriage and the object mounted on the carriage is 1 to 10 kg,
An ink jet recording apparatus in which a driving force for the carriage driving means to reciprocate the carriage is 40 N or less;
Water and an ink containing at least a polymer compound having a plurality of side chains in a hydrophilic main chain and irradiating with active energy rays can be cross-linked between the side chains are ejected from the ink jet head. An ink jet recording method comprising forming an image by irradiating an active energy ray on a recording medium on which ink is discharged. 2. The ink jet recording method according to claim 1, wherein colors of ink ejected by the ink jet head include at least four colors of yellow, magenta, cyan, and black. The inkjet recording method according to claim 1, wherein the active energy ray generation unit is mounted on the carriage. The inkjet recording method according to claim 3, wherein the active energy ray generation unit includes a fluorescent lamp. The inkjet recording method according to claim 3, wherein the active energy ray generation unit includes an LD or an LED. The ink jet recording method according to claim 1, wherein the ink is ejected from the ink jet head, and the recording medium on which the ink is ejected is irradiated with active energy rays and then dried. The ink jet recording method according to claim 1, wherein the recording medium is a coated paper for printing. The inkjet recording method according to claim 1, wherein the recording medium is a non-absorbable recording medium.

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