JP2010208343A - Inkjet image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet image forming method for performing image formation using inkjet ink excellent in strike through resistance, image scratch resistance, paper feed adaptability, and ejection property, which can perform printing to various recording media. <P>SOLUTION: In the inkjet image forming method for performing image formation by ejecting inkjet ink containing at least an oil gelling agent and active ray-curable composition which is cured by active ray onto a recording medium from an inkjet recording head, the active ray is emitted within 0.001-5 seconds after the inkjet ink is landed on the recording medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel inkjet image forming method.

  In recent years, the ink jet recording system can create images easily and inexpensively, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters. In particular, a recording device that emits and controls fine dots, ink that has improved color reproduction gamut, durability, and emission suitability, and ink absorbability, coloring material color development, surface gloss, etc. have been dramatically improved. It is also possible to obtain image quality comparable to silver halide photography using special paper. The image quality improvement of today's ink jet recording system is achieved only when all of the ink jet recording apparatus, ink jet ink, and special paper are available.

  However, in an inkjet system that requires special paper, there is a problem that the recording medium that can be used is limited, the cost of the recording medium is increased, and the like.

  On the other hand, in the office, there is an increasing need for a system that can perform high-speed full-color printing without being restricted by a recording medium (for example, plain paper, coated paper, art paper, plain paper double-sided printing, etc.). In the electrophotographic system, there is a high-speed type capable of printing 100 sheets at an A4 size per minute, but the printing is limited to monochrome images, and the printing speed is increased in color printing, the simplicity of the apparatus, the cost, In order to satisfy any requirement such as power consumption, there are still many technical problems, and the user's request has not been satisfied.

  Even in the inkjet system, when water-based ink is used, plain paper is not suitable for high-speed printing because of the long drying time of water in the ink, and when water-based ink or oil-based ink is used, the ink In the case of a recording medium such as coated paper that does not have an absorbent layer, ink droplet repelling or poor ink drying results. In addition, oil-based inks that contain volatile solvents and have improved drying properties are not environmentally friendly methods because they release a large amount of volatile solvents to the outside during drying.

  In view of the above problems, a method has been proposed for recording an image on a recording medium different from dedicated paper by an inkjet recording method. For example, a phase change ink jet method using a wax ink solid at room temperature, a solvent ink jet method using an ink mainly composed of a fast-drying organic solvent, or crosslinking by irradiation with an actinic ray, for example, ultraviolet (UV) light after recording. For example, an ultraviolet inkjet method.

  Specifically, a method is disclosed in which an alkylarylcycloalkanol is included as a gelling agent in the ink and the bleeding between the color dots of the ink is improved by utilizing the solidification ability of the gelling agent (for example, (See Patent Document 1). However, in the above proposed method, only the gelling agent is used as the ink solidifying ability, and the ink solidifying ability is not sufficient. Therefore, particularly when transported at high speed using plain paper or the like in high-speed printing, There is a problem that the ink image is peeled off from the recording medium. Moreover, in the said patent document 1, no reference is made | formed regarding using an actinic-light curable composition with a gelatinizer in an ink.

  On the other hand, a room temperature solid ink containing a low melting point wax and an ultraviolet curable resin is heated to 120 ° C. and dissolved and printed on a commercially available high-quality paper, and then irradiated with ultraviolet rays to cause image bleeding, back-off, and fixability. Means for improvement is disclosed (for example, see Patent Document 2). However, since the heating is performed at a high temperature of 120 ° C., the heat resistance of the head of the ink jet printing apparatus and the load on the ink supply system are applied, and the durability of the printing apparatus is difficult. Furthermore, since the wax is contained in a large amount of 60% by mass, it is governed by the physical properties of the wax having inferior elasticity, and there is a drawback that cracking occurs on the ink surface when plain paper is conveyed at high speed in high-speed printing. . Moreover, it is not suggested at all that the oil gelling agent which concerns on this invention is included.

  Moreover, a technique for forming a gel electrolyte by adding a gelling agent to an electrolyte of a photoelectric conversion element to prevent a decrease in photocurrent density is disclosed (for example, see Patent Document 3). No mention is made of the application of.

  Also, ink-jet ink containing an organic solvent, a colorant, and an ultraviolet curable composition is printed on a polyethylene terephthalate film, a vinyl chloride sheet, etc., cured by irradiating with ultraviolet rays using an ultraviolet irradiation device, and ink fixing by touch dry evaluation. Although a technique for improving the solvent resistance by evaluating methanol rubbing is disclosed (for example, see Patent Document 4), when these structures are applied to printing on plain paper, the time lag from ink landing to ultraviolet irradiation In addition, there is a problem that the ink permeates into the plain paper and the ink comes through and cannot be printed on both sides of the plain paper.

  In addition, hot melt ink containing a (meth) acrylic acid copolymer having a weight average molecular weight of 500 to 30,000 is heated to 120 ° C. and applied to plain paper, bending resistance, rubbing resistance, and copy paper feeding compatibility A technique for improving the performance is disclosed (for example, see Patent Document 5). Since it is heated to a high temperature of 120 ° C. in the same manner as described above, the heat resistance of the head of the ink jet printing apparatus and the members of the ink supply system are loaded, and the durability of the apparatus is difficult. In addition, when printing on coated paper, there is a problem of degradation of image rubbing that is presumed to be derived from the ink rising shape at the time of droplet landing.

JP-A-11-315245 JP-A-7-186515 Japanese Patent Laid-Open No. 11-185836 JP 2002-241654 A JP 2000-72992 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet ink that can be printed on various recording media and has excellent resistance to back-through, image scratch resistance, paper feed compatibility, and emission. It is an object of the present invention to provide an inkjet image forming method for forming an image using the method.

The above object of the present invention is achieved by the following configurations.
(Claim 1)
An inkjet image forming method for forming an image by ejecting an inkjet ink containing at least an oil gelling agent and an actinic ray curable composition curable by actinic rays from a inkjet recording head onto a recording medium. An ink jet image forming method comprising forming an image by irradiating an actinic ray for 0.001 seconds to 5 seconds after the ink for ink has landed on the recording medium.

  Moreover, a preferable embodiment is shown below.

  1) An ink-jet ink used in ink-jet recording, comprising at least an oil gelling agent and an actinic ray curable composition that is cured by actinic rays.

  2) The inkjet ink according to 1), wherein the phase transition temperature of the ink is 40 ° C. or higher and 80 ° C. or lower.

  3) The ink for ink jet recording according to 1) or 2), wherein the ink viscosity at a temperature of the phase transition temperature of the ink + 5 ° C. is 1 to 10 mPa · s.

  4) Content of the said oil gelling agent is 0.3-15 mass%, The ink for inkjets of any one of 1) -3) characterized by the above-mentioned.

  5) Melting | fusing point of the said oil gelling agent is 40-90 degreeC, The ink for inkjets of any one of 1) -4) characterized by the above-mentioned.

  6) The inkjet ink according to any one of 1) to 5), wherein the actinic ray is an ultraviolet ray and the actinic ray curable composition is a cationic polymerizable composition.

  7) The inkjet ink according to any one of 1) to 6), which contains at least one photopolymerization initiator.

  8) An ink jet recording method for recording by ejecting the ink jet ink according to any one of 1) to 7) onto a recording medium from an ink jet recording head, wherein the ink jet ink is the recording medium. An ink jet recording method comprising irradiating actinic rays within 10 seconds after landing on an ink jet.

  9) An inkjet recording method for recording by ejecting the inkjet ink according to any one of 1) to 7) onto a recording medium from an inkjet recording head, wherein the inkjet recording head is a line head type An ink jet recording method, wherein:

  According to the present invention, there is provided an ink jet image forming method capable of printing on various recording media and forming an image using an ink jet ink excellent in showthrough resistance, image scratch resistance, paper feed compatibility, and emission properties. be able to.

1 is a front view illustrating an example of a configuration of a main part of an ink jet recording apparatus that can be used in the present invention. FIG. 2 is a top view illustrating an example of a configuration of a main part of a line head type ink jet recording apparatus that can be used in the present invention.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  As a result of intensive studies in view of the above problems, the present inventors have found that an inkjet ink containing at least an oil gelling agent and an actinic ray curable composition that is cured by actinic rays is applied onto a recording medium from an inkjet recording head. An ink jet image forming method for forming an image by emitting an image, wherein after the ink jet ink has landed on the recording medium, an image is formed by irradiation with an actinic ray for 0.001 seconds to 5 seconds. Inkjet image forming method capable of printing on various recording media by the featured inkjet image forming method, and forming an image using an ink jet ink excellent in back-through resistance, image scratch resistance, paper feed compatibility, and emission properties As a result, the present invention has been found.

  By including an oil gelling agent and an actinic ray curable composition that is cured by actinic rays as an inkjet ink, the detailed reason why the above problem can be solved is presumed as follows.

  That is, by using an oil gelling agent for ink jet ink, solidification of the ink droplets is completed in a very short time when the ink droplets land on the recording medium including plain paper. It is possible to effectively prevent the diffusion of droplet components and the occurrence of show-through when using plain paper. However, only the phase inversion by the oil gelling agent (sol → gel) is insufficient in the strength of the formed image film, and the actinic ray curable composition simultaneously contained in the ink is cured by irradiation with ultraviolet rays or the like. As a result, a final image having excellent image rubbing properties can be obtained. It is presumed that the image formation having such characteristics can reduce the peeling of the printed image and the accompanying conveyance roller contamination and conveyance failure even when high-speed printing is performed.

  Details of the present invention will be described below.

  First, the oil gelling agent used for the ink-jet ink of the present invention (hereinafter also simply referred to as ink) will be described.

  The gel referred to in the present invention means that the solute has independent mobility due to the interaction such as lamellar structure, polymer network formed by covalent bond or hydrogen bond, polymer network formed by physical aggregation, and aggregate structure of fine particles. It has a structure that has been lost and assembled, and is a solidified or semi-solidified state with a sudden increase in viscosity and a significant increase in elasticity.

  The oil referred to in the present invention is a general term for compounds other than water, and the oil gelling agent according to the present invention refers to a compound that can form the gel when added to a compound other than water.

  In general, a gel becomes a fluid solution (sometimes called a sol) by heating, a thermoreversible gel that returns to the original gel when cooled, and once gelled, it can be reheated even if heated. There is a heat irreversible gel that does not return. The gel formed by the oil gelling agent according to the present invention is preferably a thermoreversible gel.

  In the ink of the present invention, the phase transition temperature of the ink is preferably 40 ° C. or higher and 80 ° C. or lower, more preferably 45 ° C. or higher and 70 ° C. or lower. If the ink phase transition temperature is 40 ° C. or higher, stable ejection is not affected by the printing environment temperature when ejecting ink droplets from the recording head (hereinafter referred to as “ejection”). If the temperature is 80 ° C. or lower, it is not necessary to heat the ink jet recording apparatus to an excessively high temperature, and the load on the head of the ink jet recording apparatus and the members of the ink supply system can be reduced.

  In order to realize the phase transition temperature of the ink defined above, the melting point of the oil gelling agent used is preferably 20 to 250 ° C, more preferably 40 to 90 ° C.

  The phase transition temperature by the sol-gel referred to in the present invention means a temperature at which the viscosity suddenly changes from a fluid solution state to a gel state, and the gel transition temperature, gel dissolution temperature, gel softening temperature, It is synonymous with the term called sol-gel phase transition temperature and gel point.

  The method for measuring the phase transition temperature of the ink of the present invention is, for example, a method in which a small iron piece sealed in a glass tube is placed in an dilatometer, and the point at which the ink liquid does not naturally fall in response to a temperature change is defined as a phase transition point. (J. Polym. Sci., 21, 57 (1956)), measuring the temperature at which an aluminum cylinder naturally falls when an aluminum cylinder is placed on the ink and the gel temperature is changed, as the phase transition temperature. (Rheological Society of Japan, Vol. 17, 86 (1989)). As a simple method, place a gel-like test piece on the heat plate, heat the heat plate, measure the temperature at which the shape of the test piece collapses, and obtain this as the sol-gel phase transition temperature. Can do.

  The oil gelling agent used in the ink of the present invention may be a high molecular compound or a low molecular compound, but is preferably a low molecular compound from the viewpoint of use in ink. Moreover, as the gel structure, a compound in which the oil gelling agent itself can form a fibrous aggregate is preferable. Formation of the fibrous aggregate can be easily confirmed by morphological observation with a transmission electron microscope.

  Specific examples of the oil gelling agent that can be used in the ink of the present invention are shown below, but the present invention is not limited only to these compounds.

  The compounds preferably used in the oil gelling agent are OG-1, OG-2, OG-5 and OG-15.

  In the ink of the present invention, the content of the oil gelling agent according to the present invention can be 0.1 to 30% by mass with respect to the total mass of the ink, but is preferably 0.3 to 15% by mass, It is particularly preferably 3 to 15% by mass. If the content of the oil gelling agent is in the range of 0.3 to 15% by mass, more stable emission characteristics can be obtained, and the object and effects of the present invention can be further exhibited. In particular, when a pigment is used as the coloring material, the oil gelling agent may impair the dispersion stability of the pigment, and therefore the oil gelling agent content is preferably in the range of 0.3 to 15% by mass.

  In the ink of the present invention containing the oil gelling agent, the ink viscosity at a temperature of the ink phase transition temperature + 5 ° C. is preferably 1 to 10 mPa · s, more preferably 1 to 5.0 mPa · s. . If the ink viscosity at a temperature of the ink phase transition temperature + 5 ° C. is in the range of 1 to 10 mPa · s, more stable emission characteristics can be obtained, and the object effect of the present invention can be further exhibited.

  Next, the actinic ray curable composition used in the inkjet ink of the present invention will be described.

  The photopolymerizable compound which is an actinic ray curable composition used in the present invention will be described. In the present invention, the photopolymerizable compound can be used without any particular limitation. Among them, a photocationically polymerizable compound or a radically polymerizable compound is preferably used, and a photocationically polymerizable compound is particularly preferable.

  As the photo cationic polymerizable monomer, various known cationic polymerizable monomers can be used. For example, the epoxies exemplified in JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, JP-A-2001-220526 Compounds, vinyl ether compounds, oxetane compounds and the like.

  In the present invention, for the purpose of suppressing the shrinkage of the recording medium during ink curing, it contains at least one oxetane compound as a photopolymerizable compound and at least one compound selected from an epoxy compound and a vinyl ether compound. Is preferred.

  A preferable aromatic epoxide is a di- or polyglycidyl ether produced by the reaction of a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof and epichlorohydrin, such as bisphenol A or an alkylene oxide thereof. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or alkylene oxide adducts thereof, and novolak type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

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

  Preferred aliphatic epoxides include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or Diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or alkylene oxide adduct thereof, polyethylene glycol or alkylene oxide adduct thereof Of polyalkylene glycols such as diglycidyl ether, polypropylene glycol or diglycidyl ether of its alkylene oxide adduct Glycidyl ether, and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  Among these epoxides, in view of fast curability, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable. In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

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

  Among these vinyl ether compounds, in consideration of curability, adhesion, and surface hardness, di- or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable. In the present invention, one of the above vinyl ether compounds may be used alone, or two or more thereof may be used in appropriate combination.

  The oxetane compound according to the present invention is a compound having an oxetane ring, and any known oxetane compound as introduced in JP-A Nos. 2001-220526 and 2001-310937 can be used.

  In the oxetane compound according to the present invention, when a compound having 5 or more oxetane rings is used, the viscosity of the ink is increased. Therefore, in the present invention, a compound having 1 to 4 oxetane rings is preferable.

  Hereinafter, although the specific example of the compound which has an oxetane ring based on this invention is demonstrated, this invention is not limited to these.

  An example of the compound having one oxetane ring is a compound represented by the following general formula (1).

In the general formula (1), R ¹ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, or an aryl group. , Furyl group or thienyl group. R ² represents an alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl- C2-C6 alkenyl group such as 2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group, phenoxyethyl group, etc. A group having an aromatic ring, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethylcarbonyl group, a propylcarbonyl group, and a butylcarbonyl group, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethoxycarbonyl group, a propoxycarbonyl group, and a butoxycarbonyl group; Alkoxycarbonyl group, ethylcarbamoyl group, propylcarbamoyl group, butylcarbamoyl group, pentylcarbamoyl An N-alkylcarbamoyl group having 2 to 6 carbon atoms, such as a group; As the oxetane compound used in the present invention, it is particularly preferable to use a compound having one oxetane ring because the resulting composition has excellent tackiness, low viscosity and excellent workability.

  An example of a compound having two oxetane rings includes a compound represented by the following general formula (2).

In the general formula (2), R ¹ is the same group as that in the general formula (1). R ³ is, for example, a linear or branched poly (alkyleneoxy) group such as a linear or branched alkylene group such as an ethylene group, a propylene group or a butylene group, a poly (ethyleneoxy) group or a poly (propyleneoxy) group. ) Group, propenylene group, methylpropenylene group, butenylene group or other linear or branched unsaturated hydrocarbon group, alkylene group containing carbonyl group or carbonyl group, alkylene group containing carboxyl group, alkylene containing carbamoyl group Group.

As the R ^3, the following general formula (3) can also include polyvalent group selected from groups represented by (4) and (5).

In the general formula (3), R ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. An alkoxy group having 1 to 4 carbon atoms, a halogen atom such as a chlorine atom or a bromine atom, a nitro group, a cyano group, a mercapto group, a lower alkyl carboxyl group, a carboxyl group, or a carbamoyl group.

In the general formula (4), R ⁵ represents an oxygen atom, a sulfur atom, a methylene group, NH, SO, SO ₂ , C (CF ₃ ) ₂ , or C (CH ₃ ) ₂ .

In General formula (5), R < ⁶ > is a C1-C4 alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, or an aryl group. n is an integer of 0-2000. R ⁷ is a methyl group, an ethyl group, a propyl group, a butyl group having 1 to 4 carbon atoms, or an aryl group. R ⁷ may further include a group selected from the group represented by the following general formula (6).

In the general formula (6), R ⁸ is a methyl group, an ethyl group, a propyl group, butyl alkyl group having 1 to 4 carbon atoms such as a group, or an aryl group. m is an integer of 0-100.

  Specific examples of the compound having two oxetane rings include the following compounds.

Exemplary compound 1 is a compound in which R ¹ is an ethyl group and R ³ is a carboxyl group in the general formula (2). Exemplary compound 2 is a compound in which, in the general formula (2), R ¹ is an ethyl group, R ³ is the general formula (5), R ⁶ and R ⁷ are methyl groups, and n is 1.

Among the compounds having two oxetane rings, preferred examples other than the above compounds include compounds represented by the following general formula (7). In general formula (7), ^{R 1} has the same meaning as ^{R 1} in the general formula (1).

  An example of a compound having 3 to 4 oxetane rings is a compound represented by the following general formula (8).

In the general formula (8), ^{R 1} is the same meaning as ^{R 1} in the general formula (1). As R ⁹ , for example, a branched alkylene group having 1 to 12 carbon atoms such as groups represented by the following A to C, a branched poly (alkyleneoxy) group such as a group represented by the following D, or the following E And branched polysiloxy groups such as those shown. j is 3 or 4.

In the above A, R ¹⁰ is a lower alkyl group such as a methyl group, an ethyl group, or a propyl group. Moreover, in said D, p is an integer of 1-10.

  Illustrative compound 3 is an example of a compound having 3 to 4 oxetane rings.

  Furthermore, examples of the compound having 1 to 4 oxetane rings other than those described above include compounds represented by the following general formula (9).

In the general formula (9), ^{R 8} has the same meaning as ^{R 8} in the general formula (6). R ¹¹ is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, or a trialkylsilyl group, and r is 1 to 4.

  Preferable specific examples of the oxetane compound used in the present invention include the following compounds.

  The method for producing each compound having an oxetane ring described above is not particularly limited, and may be a conventionally known method, for example, Pattisson (DB Pattison, J. Am. Chem. Soc., 3455, 79). (1957)) discloses a method for synthesizing an oxetane ring from a diol. In addition to these, compounds having 1 to 4 oxetane rings having a high molecular weight of about 1000 to 5000 are also included. Examples of these specific compounds include the following compounds.

  Next, the radical polymerizable compound will be described.

  Examples of the radical polymerizable compound include photopolymerizable compositions described in JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, and JP-A-10-863. The photocurable material used and the cationic polymerization type photocurable resin are known, and the cationic polymerization type photocurable resin sensitized to a long wavelength region longer than visible light is also disclosed in, for example, -43633, JP-A-8-324137, and the like.

  The radical polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and may be any compound as long as it has at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. , Oligomers, polymers and the like having a chemical form. Only one kind of radically polymerizable compound may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties.

  Examples of compounds having an ethylenically unsaturated bond capable of radical polymerization include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and their salts, esters, urethanes, amides. And radically polymerizable compounds such as unsaturated monomers, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. Specifically, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol Diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol Tetraacrylate, dipentaery Acrylic acid derivatives such as lithol tetraacrylate, trimethylolpropane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, N-methylol acrylamide, diacetone acrylamide, epoxy acrylate, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate , Lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylol Methacryl derivatives such as tan trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate More specifically, Yamashita Junzo, “Crosslinker Handbook”, (1981 Taiseisha); Kato Kiyomi, “UV / EB Curing Handbook (Materials)” (1985, Polymer Publication) ); Rad-Tech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products described in the above, or radically polymerizable or crosslinkable monomers known in the industry Oligomers and polymers can be used. The amount of the radical polymerizable compound added is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

  As a cationic polymerization type photo-curing resin, a type (mainly epoxy type) of an epoxy type UV curable prepolymer that is polymerized by cationic polymerization, the monomer contains two or more epoxy groups in one molecule. Mention may be made of prepolymers. Examples of such prepolymers include alicyclic polyepoxides, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyhydric alcohols, polyglycidyl ethers of polyoxyalkylene glycols, and polyglycidyls of aromatic polyols. Examples include ethers, hydrogenated compounds of polyglycidyl ethers of aromatic polyols, urethane polyepoxy compounds, and epoxidized polybutadienes. One of these prepolymers can be used alone, or two or more thereof can be mixed and used.

  Other examples of the cationic polymerizable compound contained in the cationic polymerizable composition include the following (1) styrene derivatives, (2) vinyl naphthalene derivatives, (3) vinyl ethers, and (4) N-vinyl compounds. Can be mentioned.

(1) Styrene derivatives Examples include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, p-methoxy-β-methylstyrene, and the like.

(2) Vinylnaphthalene derivatives For example, 1-vinylnaphthalene, α-methyl-1-vinylnaphthalene, β-methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene, 4-methoxy-1-vinylnaphthalene, etc. is there.

(3) Vinyl ethers For example, isobutyl vinyl ether, ethyl vinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-methoxyphenyl vinyl ether, α-methylphenyl vinyl ether, β-methylisobutyl vinyl ether, β-chloroisobutyl vinyl ether and the like.

(4) N-vinyl compounds such as N-vinylcarbazole, N-vinylpyrrolidone, N-vinylindole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylacetanilide, N-vinylethylacetamide, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam, N-vinylimidazole and the like.

  The ink of the present invention preferably contains at least one photopolymerization initiator.

  Photopolymerization initiators can be broadly classified into two types: intramolecular bond cleavage type and intramolecular hydrogen abstraction type.

  Examples of the intramolecular bond cleavage type photopolymerization initiator include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2. -Hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4 Acetophenones such as -thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone; benzoins such as benzoin, benzoin methyl ether, benzoin isopropyl ether; 2 , 4,6-Trimethylbenzoindiphenyl Scan fins oxides such acylphosphine oxide of benzil, methyl phenylglyoxylate esters.

  On the other hand, as an intramolecular hydrogen abstraction type photopolymerization initiator, for example, benzophenone, methyl 4-phenylbenzophenone, o-benzoylbenzoate, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl Benzophenones such as diphenyl sulfide, acrylated benzophenone, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 3,3'-dimethyl-4-methoxybenzophenone; 2-isopropylthioxanthone, 2 Thioxanthone series such as 1,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone; amino benzophenone series such as Michler-ketone, 4,4'-diethylaminobenzophenone; 10-butyl- - chloro acridone, 2-ethyl anthraquinone, 9,10-phenanthrenequinone, camphorquinone, and the like.

  The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 10.00% by mass of the actinic ray curable composition.

  Examples of radical polymerization initiators include triazine derivatives described in JP-B-59-1281, JP-B-61-9621, JP-A-60-60104, JP-A-59-1504, and JP-A-59-1504. Organic peroxides described in JP-A-61-243807, JP-B-43-23684, JP-B-44-6413, JP-B-44-6413, JP-B-47-1604, etc., and the United States Diazonium compounds described in Japanese Patent No. 3,567,453, organic azides described in US Pat. Nos. 2,848,328, 2,852,379 and 2,940,853 Compounds, ortho-quinonediazides described in JP-B 36-22062, JP-B 37-13109, JP-B 38-18015, JP-B 45-9610 and the like, Various onium compounds described in JP-A-55-39162, JP-A-59-14023, and the like, and “Macromolecules, Vol. 10, page 1307 (1977); No. 142205, JP-A-1-54440, European Patent No. 109,851, European Patent No. 126,712, etc., “Journal of Imaging Science” (J. Imag. Sci.), Vol. 30, page 174 (1986), (oxo) sulfonium organoboron complexes described in Japanese Patent Nos. 2711491 and 2803454, 61-151197, titanocenes, “Coordination Chemistry Levi A transition metal complex containing a transition metal such as ruthenium described in (Coordination Chemistry Review), 84, 85-277 (1988) and JP-A-2-182701, No. 2,4,5-triarylimidazole dimer, carbon tetrabromide, and organic halogen compounds described in JP-A-59-107344. These polymerization initiators are preferably contained in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the compound having an ethylenically unsaturated bond capable of radical polymerization.

  In the ink of the present invention, a photoacid generator can also be used.

  As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), 187. To page 192). Examples of compounds suitable for the present invention are listed below.

First, diazonium, ammonium, iodonium, sulfonium, aromatic onium compounds such as phosphonium ^{_{B (C 6 F 5) 4}} -, PF 6 -, AsF 6 -, SbF 6 -, CF 3 SO 3 - and salts be able to.

  Specific examples of onium compounds that can be used in the present invention are shown below.

  Secondly, sulfonated substances that generate sulfonic acid can be mentioned, and specific compounds thereof are exemplified below.

  Thirdly, halides that generate hydrogen halide can also be used, and specific compounds thereof are exemplified below.

  Fourthly, an iron allene complex can be mentioned.

  Next, each component of the ink of the present invention excluding the above items will be described.

  The coloring material used in the ink of the present invention is not particularly limited, and dyes or pigments can be used, but oil-soluble dyes and pigments are preferred.

  Specific examples of oil-soluble dyes that can be used in the present invention are given below, but the present invention is not limited to these.

<Magenta dye>
MS Magenta VP, MS Magenta HM-1450, MS Magenta HSo-147 (manufactured by Mitsui Toatsu Co., Ltd.), AIZENSOT Red-1, AIZEN SOT Red-2, AIZEN SOTRed-3, AIZEN SOT Pink-1, EPIRON Red GE SPECIAL (above, manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN Red FB 200%, MACROLEX Red Violet R, MACROLEX ROT5B (above, manufactured by Bayer Japan), KAYASET Red B, KAYASET Red 130, KAYASET Red Japan 802 ), PHLOXIN, ROSE BENGAL, ACID Red (above, made by Daiwa Kasei), HSR-31, DIARESIN Red K (below) , Manufactured by Mitsubishi Kasei Co., Ltd.), Oil Red (manufactured by BASF Japan Co., Ltd.).

<Cyan dye>
MS Cyan HM-1238, MS Cyan HSo-16, Cyan HSo-144, MS Cyan VPG (manufactured by Mitsui Toatsu Co., Ltd.), AIZEN SOT Blue-4 (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN BR. Blue BGLN 200%, MACROLEX Blue RR, CERES Blue GN, SIRIUS SUPRATURQ. Blue Z-BGL, SIRIUS SUTRA TURQ. Blue FB-LL 330% (above, Bayer Japan), KAYASET Blue FR, KAYASET Blue N, KAYASET Blue 814, Turq. Blue GL-5 200, Light Blue BGL-5 200 (above, Nippon Kayaku Co., Ltd.), DAIWA Blue 7000, Oleosol Fast Blue GL (above, Daiwa Kasei), DIARESIN Blue P (Mitsubishi Kasei), SUDAN Blue 670, NEOPEN Blue 808, ZAPON Blue 806 (above, manufactured by BASF Japan).

<Yellow dye>
MS Yellow HSm-41, Yellow KX-7, Yellow EX-27 (Mitsui Toatsu), AIZEN SOT Yellow-1, AIZEN SOT YellowW-3, AIZEN SOT Yellow-6 (above, manufactured by Hodogaya Chemical Co., Ltd.), MACROLEX Yellow 6G, MACROLEX FLUOR. Yellow 10GN (above, manufactured by Bayer Japan), KAYASET Yellow SF-G, KAYASET Yellow 2G, KAYASET Yellow AG, KAYASET Yellow EG (above, manufactured by Nippon Kayaku Co., Ltd.), Daiwa Yellow 330H HSY-68 (manufactured by Mitsubishi Kasei Co., Ltd.), SUDAN Yellow 146, NEOPEN Yellow 075 (above, manufactured by BASF Japan).

<Black dye>
MS Black VPC (Mitsui Toatsu Co., Ltd.), AIZEN SOT Black-1, AIZEN SOT Black-5 (above, Hodogaya Chemical Co., Ltd.), RESORIN Black GSN 200%, RESOLIN Black BS (above, Bayer Japan Co., Ltd.), KAYASET Black A-N (manufactured by Nippon Kayaku Co., Ltd.), DAIWA Black MSC (manufactured by Daiwa Kasei Co., Ltd.), HSB-202 (manufactured by Mitsubishi Kasei Co., Ltd.), NEPTUNE Black X60, NEOPEN Black X58 (manufactured by BASF Japan) .

  Next, the pigment will be described.

  In the ink of the present invention, a pigment having good dispersion stability with respect to the ink component and excellent weather resistance can be preferably used. Although it does not necessarily limit as a pigment, For example, the organic or inorganic pigment of the following number described in a color index can be used for this invention.

  Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, and 53: 1. 57: 1, 57: 2, 58: 4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 104, 108, 112, 122, 123, 144, 146 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13 16, 20, 36, blue or cyan pigments include Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 1 7-1, 22, 27, 28, 29, 36, 60, as green pigment, Pigment Green 7, 26, 36, 50, as yellow pigment, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, and black pigments such as Pigment Black 7, 28, 26 can be used depending on the purpose.

  Specific product names include, for example, chromofine yellow 2080, 5900, 5930, AF-1300, 2700L, chromofine orange 3700L, 6730, chromofine scarlet 6750, chromofine magenta 6880, 6886, 6891N, 6790, 6887. , Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, Chromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Ku Mofine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400 (B), 2500, 2600, ZAY-260, 2700 (B), 2770, Seika Fast Red 8040 , C405 (F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B1476T-7, 1483LT, 3840, 3870 , Seika Fast Bordeaux 10B-430, Seica Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C7 18, A612, cyanine blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichi Seika Kogyo), KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302 , 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (large Nippon Ink Chemical Co., Ltd.), Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pi gment Yellow 1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, C USN, Colortex Maroon 601, Colortex Brown B610N, Colortex violet 600, Pigment Red 122, Colortex Blue 516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403B, Col. , Lionol lue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink), Toner Magenta E02, Permanent RubinF6B, Toner Yellow HG, Permanent Yellow GG-02, Black Bumpy Carbon G2 , # 2400, # 2350, # 2200, # 1000, # 990, # 980, # 970, # 960, # 950, # 850, MCF88, # 750, # 650, MA600, MA7, MA8, MA11, MA100, MA100R , MA77, # 52, # 50, # 47, # 45, # 45L, # 40, # 33, # 32, # 30, # 25, # 20, # 10, # 5, # 44, And the like, such as F9 (manufactured by Mitsubishi Chemical).

  Further, it is also possible to use a dispersion liquid in which the pigment is dispersed in high concentration in advance in water, a solvent, a polymerizable monomer or the like.

  Dispersing agents used to disperse the pigment include, for example, higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, polyoxy Activators such as alkylene alkyl ether phosphates, polyoxyalkylene alkyl phenyl ethers, polyoxyethylene polyoxypropylene glycols, glycerin esters, sorbitan esters, polyoxyethylene fatty acid amides, amine oxides, or styrene, styrene derivatives, vinyl naphthalene Block copolymer comprising two or more monomers selected from derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, random Polymers and can be exemplified salts thereof.

  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. It is also possible to add a dispersant when dispersing the pigment.

  The pigment is preferably dispersed with an average particle size of 0.08 to 0.5 μm, and the maximum particle size is 0.3 to 10 μm, preferably 0.3 to 3 μm. Set selection, dispersion conditions, and filtration conditions. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

  The amount of pigment or oil-soluble dye added is preferably 0.1 to 20% by mass, more preferably 0.4 to 10% by mass. If it is 0.1% by mass or more, good image quality can be obtained, and if it is 20% by mass or less, an appropriate ink viscosity in ink ejection can be obtained. In addition, two or more kinds of colorants can be mixed as appropriate for color adjustment.

  Various organic solvents can be used in the ink of the present invention.

  Examples of solid oily media include beeswax, carnauba wax, rice wax, wood wax, jojoba oil, whale wax, candelilla wax, lanolin, montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, petrolactam. Natural waxes such as polyethylene wax, chlorinated hydrocarbons, palmitic acid, stearic acid, behenic acid, tiglic acid, 2-acetonaphthobehenic acid, 12-hydroxystearic acid, dihydroxystearic acid and other organic acids; dodecanol, tetradeca Nord, Hexadecanol, Eicosanol, Docosanol, Tetracosanol, Hexacosanol, Octacosanol, Dodecenol, Myricyl Alcohol, Tetracenol, Hexadecenol, Eicosenol, Docoseno , Pinene glycol, hinokiol, butynediol, nonanediol, isophthalyl alcohol, mesicerine, hexanediol, decanediol, tetradecandiol, hexadecandiol, docosandiol, tetracosandiol, tvneol, phenylglycerin, eicosandiol , Octanediol, phenylpropylene glycol and other alcohols; bisphenol A, p-α-cumylphenol and other phenols; organic acid esters of the above organic acids such as glycerin, ethylene glycol and diethylene glycol; stearic acid cholesterol, palmitic acid cholesterol , Cholesterol, myristic acid cholesterol, behenic acid cholesterol, lauric acid cholesterol, melicinate cholesterol, etc. Fatty acid esters; saccharide fatty acid esters such as sucrose stearate, sucrose palmitate, saccharose behenate, saccharose laurate, saccharose melicinate, lactose stearate, lactose palmitate, lactose behenate, lactose laurate, lactose lactate; benzoyl Ketones such as acetone, diacetobenzene, benzophenone, tricosanone, heptacosanone, heptatriacontanone, hentriacontanone, stearone, laurone; oleic acid amide, lauric acid amide, stearic acid amide, ricinoleic acid amide, palmitic acid amide, Tetrahydrofuranamide, erucic acid amide, myristic acid amide, 12-hydroxystearic acid amide, N-stearyl erucic acid amide N-oleylstearic acid amide, N, N-ethylenebislauric acid amide, N, N-ethylenebisstearic acid amide, N, N-ethylenebisbehenic acid amide, N, N-xylylene bisstearic acid amide, N, N-butylenebisstearic acid amide, N, N-dioleyl adipic acid amide, N, N-dioleyl sebacic acid amide, N, N-distearyl sebacic acid amide, N, N-distearyl terephthalic acid amide, phenacetin, Amides such as toluamide and acetamide; Sulfonamides such as p-toluenesulfonamide, ethylbenzenesulfonamide and butylbenzenesulfonamide; Alkylnaphthalenes such as α-methylnaphthalene, β-methylnaphthalene and 2,6-dimethylnaphthalene; Dibutyl naphthalate, geo Chirufutareto, dibutyl adipate, dimethyl terephthalate, benzyl benzoate, carboxylic acid esters such as naphthalene-2,6-dicarboxylic acid methyl ester; tributyl phosphate, phosphoric acid esters such as triphenyl phosphate; and the like.

  Examples of the liquid oily medium include one organic solvent or a mixed solvent of two or more organic solvents. Examples of the organic solvent include ethanol, pentanol, heptanol, octanol, cyclohexanol, benzyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, furfuryl alcohol, anis alcohol, and the like; ethylene glycol monoethyl ether, ethylene glycol monophenyl Ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol diacetate, ethylene glycol Monoethyl ether ace And glycol derivatives such as propylene glycol diacetate; ketones such as benzyl methyl ketone, diacetone alcohol, and cyclohexanone; ethers such as butyl phenyl ether, benzyl ethyl ether, and hexyl ether; ethyl acetate, amyl acetate, benzyl acetate, Phenylethyl acetate, phenoxyethyl acetate, ethyl phenylacetate, benzyl propionate, ethyl benzoate, butyl benzoate, ethyl laurate, butyl laurate, isopropyl myristate, isopropyl palmitate, triethyl phosphate, tributyl phosphate, phosphoric acid Tricresyl, diethyl phthalate, dibutyl phthalate, diethyl malonate, dipropyl malonate, diethyl diethyl malonate, diethyl succinate, dibutyl succinate, glutaric acid Ethyl, diethyl adipate, dibutyl adipate, di (2-methoxyethyl) adipate, diethyl sebacate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate, dioctyl fumarate, 3-hexenyl cinnamate, etc. Esters of hydrocarbons; hydrocarbon solvents such as petroleum ether, petroleum benzyl, tetralin, delican, 1-amylbenzene, dimethylnaphthalene; acetonitrile, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane And polar solvents such as propylene carbonate, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, and N, N-diethyldodecanamide. These solvents may be used alone or in combination of two or more.

  In the ink of the present invention, in addition to the above description, if necessary, the output stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performance improvement objectives are known. Various additives such as a viscosity modifier, a specific resistance modifier, a film forming agent, an ultraviolet absorber, an antioxidant, a discoloration inhibitor, an antifungal agent, and a rust inhibitor can be appropriately selected and used.

  The recording medium that can be used for image formation with the ink of the present invention is not particularly limited, and is made of a paper base such as plain paper or art paper used for copying, ordinary uncoated paper, base paper, etc. In addition to coated paper with both surfaces coated with resin, various non-absorbable plastics and films used for so-called soft packaging can be used. Examples of various plastic films include PET film, OPS film, and OPP. A film, an ONy film, a PVC film, a PE film, and a TAC film can be mentioned. Moreover, it is applicable also to metals and glass.

  Next, the ink jet recording method of the present invention will be described.

  In the ink jet recording method of the present invention, an ink containing the oil gelling agent of the present invention and an actinic ray curable composition is ejected onto a recording medium by an ink jet recording method, and then ink droplets are gelled by the oil gelling agent. Thereafter, a method of irradiating actinic rays such as ultraviolet rays to cure the ink is preferable.

(Total ink film thickness after ink landing)
In the present invention, the total ink film thickness after the ink has landed on the recording medium and cured by irradiation with actinic rays is preferably 2 to 25 μm. Here, “total ink film thickness” means the maximum value of the film thickness of the ink drawn on the recording medium, and even for a single color, other two colors are superimposed (secondary color), three colors are superimposed, four colors are used. Even when recording is performed by the overlapping (white ink base) inkjet recording method, the meaning of the total ink film thickness is the same.

(Ink ejection conditions)
As the ink ejection conditions, it is preferable from the viewpoint of ejection stability that the recording head and ink are heated to 35 to 100 ° C. and ejected. The ink of the present invention has a large viscosity fluctuation range due to temperature fluctuation, and the viscosity fluctuation directly affects the droplet size and droplet ejection speed, causing image quality degradation. It is preferable to keep in and emit in that state. The predetermined temperature range is preferably set temperature ± 5 ° C., more preferably set temperature ± 2 ° C., and further preferably set temperature ± 1 ° C. The set temperature here refers to a reference temperature set as the temperature of ink when ink is ejected.

  In the present invention, the amount of liquid droplets ejected from each nozzle of the recording head is preferably 2 to 15 pl. Originally, in order to form a high-definition image, it is necessary for the amount of droplets to be within this range, but when discharging with this amount of droplets, the above-described discharge stability becomes particularly severe. According to the present invention, even when ejection is performed with a small droplet amount such as 2 to 15 pl, the ejection stability is improved and a high-definition image can be stably formed.

(Light irradiation conditions after ink landing)
In the image forming method of the present invention, it is preferable that the active light is applied within 10 seconds after the ink landing as the irradiation condition of the active light, more preferably 0.001 to 5 seconds, and still more preferably 0. .001 seconds to 2 seconds. In order to form a high-definition image, it is an important requirement that the irradiation timing be as early as possible.

  A basic method of actinic ray irradiation is disclosed in JP-A-60-132767. According to this, the light source is provided on both sides of the head unit, and the head and the light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In US Pat. No. 6,145,979, as an irradiation method, a method using an optical fiber or a method of applying a collimated light source to a mirror surface provided on the side of the head unit and irradiating the recording unit with UV light is disclosed. Yes. Any of these irradiation methods can be used in the image forming method of the present invention.

  In addition, the irradiation of actinic rays is divided into two stages. First, actinic rays are irradiated by the above-described method within 0.001 to 2.0 seconds after ink landing, and actinic rays are further irradiated after all printing is completed. The method is also a preferred embodiment. By dividing the irradiation of actinic rays into two stages, it is possible to further suppress the shrinkage of the recording medium that occurs during ink curing.

  Conventionally, in the UV ink jet system, a light source with high illuminance in which the total power consumption of the light source exceeds 1 kW · hr is usually used in order to suppress dot spreading and bleeding after ink landing. However, when these light sources are used, particularly in printing on a shrink label or the like, the shrinkage of the recording medium is so large that it cannot be used practically.

  In the present invention, it is preferable to use an actinic ray having a maximum illuminance in a wavelength region of 254 nm, and a high-definition image can be formed even when a light source having a total power consumption of 1 kW · hr or more is used, and the recording medium is contracted. Is also within a practically acceptable level.

In the present invention, it is preferable that the total power consumption of the light source for irradiating actinic rays is less than 1 kW · hr. Examples of the light source having a total power consumption of less than 1 kW · hr include, but are not limited to, a fluorescent tube, a cold cathode tube, a hot cathode tube, and an LED. Moreover, it is preferable that it is 0.1-50 mW / cm < ² > as an irradiation dose.

  Next, an example of an ink jet recording apparatus (hereinafter simply referred to as a recording apparatus) that can be used in the ink jet recording method of the present invention will be described.

  Hereinafter, a recording apparatus that can be used in the present invention will be described with reference to the drawings as appropriate. Note that the recording apparatus shown in the drawings is merely an embodiment of the recording apparatus that can be preferably used in the present invention, and the present invention is not limited to this drawing.

  FIG. 1 is a front view showing an example of a configuration of a main part of an ink jet recording apparatus that can be used in the present invention. The recording apparatus 1 includes a head carriage 2, a recording head 3, irradiation means 4 as means for irradiating actinic rays, a platen unit 5, and the like. In the recording apparatus 1, the platen unit 5 is installed under the recording medium P. The platen unit 5 has a function of absorbing ultraviolet rays, and absorbs excess ultraviolet rays that have passed through the recording medium P. As a result, a high-definition image can be reproduced very stably.

  The recording medium P is guided by the guide member 6 and moves from the near side to the far side in FIG. 1 by the operation of the conveying means (not shown). A head scanning unit (not shown) scans the recording head 3 held by the head carriage 2 by reciprocating the head carriage 2 in the Y direction in FIG.

  The head carriage 2 is installed on the upper side of the recording medium P and accommodates a plurality of recording heads 3 to be described later according to the number of colors used for image printing on the recording medium P and an ejection port (nozzle) arranged on the lower side. To do. The head carriage 2 is installed with respect to the main body of the recording apparatus 1 in such a manner that it can reciprocate in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by driving the head scanning means.

  In FIG. 1, the head carriage 2 is white (W), yellow (Y), magenta (M), cyan (C), black (K), light yellow (Ly), light magenta (Lm), and light cyan (Lc). In the drawing, the recording head 3 for light black (Lk) and white (W) is drawn. However, the number of the recording heads 3 accommodated in the head carriage 2 and the number of the recording heads 3 are accommodated in the embodiment. The color of the ink to be determined is appropriately determined.

  The recording head 3 records the ink containing the actinic radiation curable composition supplied from the ink supply means (not shown) from the discharge port by the operation of a plurality of discharge means (not shown) provided therein. The ink is discharged toward the medium P. The ink ejected by the recording head 3 is composed of a coloring material, a polymerizable monomer, an initiator and the like in addition to the oil gelling agent. After landing on the recording medium P, the ink is cooled and gelled. In the example, when irradiated with ultraviolet rays as an irradiation means, the photopolymerization initiator has a property of being cured by a monomer crosslinking or polymerization reaction accompanying the action of a photopolymerization initiator as a catalyst.

  The recording head 3 moves from one end in the width direction of the recording medium P to the other end of the recording medium P in the Y direction in FIG. The ink of the present invention is ejected as ink droplets on the possible region), and the ink droplets are landed on the landable region.

  The above-described scanning is performed as many times as necessary, and after the ink of the present invention is ejected toward one landing possible region, the recording medium P is appropriately moved from the front to the back in FIG. The ink of the present invention is ejected to the next landable area adjacent to the rearward direction in FIG.

  By repeating the above-described operation and ejecting the ink of the present invention from the recording head 3 in conjunction with the head scanning means and the conveying means, an image composed of the aggregate of the ink of the present invention is formed on the recording medium P.

  The irradiation unit 4 includes an ultraviolet lamp that emits ultraviolet light in a specific wavelength region with stable exposure energy and a filter that transmits ultraviolet light of a specific wavelength. Here, as the ultraviolet lamp, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a black light, an LED (light emitting diode), and the like can be applied. A cathode tube, a hot cathode tube, a mercury lamp or black light is preferred. In particular, a low-pressure mercury lamp, a hot cathode tube, a cold cathode tube, and a germicidal lamp that emit ultraviolet light having a wavelength of 254 nm are preferable because they can prevent bleeding and control the dot diameter efficiently. By using black light as the active light source of the irradiation means 4, the irradiation means 4 for curing the UV ink can be produced at low cost.

  The irradiating means 4 has the same shape as the largest one that can be set by the recording apparatus 1 among the landable areas where the recording head 3 ejects UV ink by one scan driven by the head scanning means, or from the landable area. Also has a large shape.

  The irradiation means 4 is fixed on both sides of the head carriage 2 so as to be substantially parallel to the recording medium P.

  As described above, as a means for adjusting the illuminance of the ink discharge portion, not only the entire recording head 3 is shielded, but in addition, the ink discharge of the recording head 3 is determined from the distance h1 between the irradiation means 4 and the recording medium P. It is effective to increase the distance h2 between the portion 31 and the recording medium P (h1 <h2), to separate the recording head 3 from the irradiation means 4, or to increase the distance between them. Further, it is more preferable to provide a bellows structure 7 between the recording head 3 and the irradiation means 4.

  Here, the wavelength of the ultraviolet rays irradiated by the irradiation means 4 can be changed as appropriate by replacing the ultraviolet lamp or filter provided in the irradiation means 4.

  The ink of the present invention has excellent ejection stability and is particularly effective when an image is formed using a line head type recording apparatus.

  FIG. 2 is a top view illustrating an example of a configuration of a main part of a line head type ink jet recording apparatus that can be used in the present invention. Those having the same functions as those shown in FIG. 1 will be described using the same reference numerals as those in FIG.

  The ink jet recording apparatus shown in FIG. 2 is called a line head system, and a plurality of ink jet recording heads 3 of each color are fixedly arranged on the head carriage 2 so as to cover the entire width of the recording medium P. Has been.

  On the other hand, on the downstream side of the head carriage 2, there is provided irradiation means 4 arranged so as to cover the entire width of the recording medium P and cover the entire width direction of the ink printing surface. As the ultraviolet lamp used in the illuminating means 4, the same one as described in FIG. 1 can be used.

  In the line head system shown in FIG. 2, the head carriage 2 and the irradiating means 4 are fixed, and only the recording medium P is transported, and ink is ejected and cured to form an image.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<Preparation of ink>
[Preparation of Ink 1: Comparative Example]
Color material: C.I. I. Pigment Blue 15: 3 (average particle size: 100 nm) 5 parts by mass Paraffin wax (manufactured by Nippon Seiwa Co., Ltd., 155) 45 parts by mass Behenic acid (manufactured by Wako Pure Chemical Industries, Ltd.) 30 parts by mass Oleic acid amide (manufactured by Kao Corporation, fatty acid) Amide ON) 20 parts by mass The above additives were sequentially mixed, heated to 150 ° C. and stirred, and then the obtained liquid was filtered through a filter under heating and cooled to prepare ink 1.

[Preparation of Ink 2: Comparative Example]
Color material: C.I. I. Pigment Blue 15: 3 (average particle size: 100 nm) 5 parts by mass Oil gelling agent (Exemplary Compound OG-12) 45 parts by mass Behenic acid (manufactured by Wako Pure Chemical Industries, Ltd.) 30 parts by mass Oleic acid amide (manufactured by Kao Corporation, fatty acid amide) ON) 20 parts by mass The above substances were mixed in sequence, heated to 80 ° C. and stirred, and then the obtained liquid was filtered with a filter under heating and cooled to prepare ink 2.

[Preparation of Ink 3: Comparative Example]
<Preparation of Cyan Pigment Dispersion 1>
C. I. Pigment Blue 15: 3 20 parts by mass Polymer dispersing agent (Solsperse series manufactured by Zeneca) 5 parts by mass Stearyl acrylate 75 parts by mass After mixing the above substances, the average particle size of the pigment particles is 0.2 to 0.3 μm. Using a known dispersing device, the dispersion conditions were appropriately adjusted so as to be within the range, dispersion was performed, and filter filtration was then performed under heating to prepare cyan pigment dispersion 1.

<Preparation of ink>
Cyan pigment dispersion 1 5 parts by weight Photopolymerizable compound 1: Lauryl acrylate (monofunctional) 10 parts by weight Photopolymerizable compound 2: Ethylene oxide modified trimethylolpropane triacrylate (trifunctional) 10 parts by weight Photopolymerizable compound 3: Caprolactam-modified dipentaerythritol hexaacrylate (hexafunctional) 40 parts by mass Photopolymerizable compound 4: Tetraethylene glycol diacrylate (bifunctional) 30 parts by mass Polymerization initiator 1: Irgacure 184 (Nippon Ciba Geigy) 2.5 parts by mass Polymerization initiator 2: Irgacure 907 (manufactured by Ciba Geigy Japan Co., Ltd.) 2.5 parts by mass The above substances were sequentially added and mixed, and then filtered using a filter having an absolute filtration accuracy of 2 μm to prepare ink 3.

[Preparation of Ink 4: Comparative Example]
Cyan pigment dispersion 1 (supra) 5 parts by mass Paraffin wax (manufactured by Nippon Seiwa Co., Ltd., 155) 45 parts by mass Photopolymerizable compound 1: Lauryl acrylate (monofunctional) 5.5 parts by mass Photopolymerizable compound 2: Ethylene Oxide-modified trimethylolpropane triacrylate (trifunctional) 5.5 parts by mass Photopolymerizable compound 3: Caprolactam-modified dipentaerythritol hexaacrylate (hexafunctional) 22 parts by mass Photopolymerizable compound 4: Tetraethylene glycol diacrylate (bifunctional) ) 17 parts by mass Polymerization initiator 1: Irgacure 184 (manufactured by Ciba Geigy Japan) 2.5 parts by mass Polymerization initiator 2: Irgacure 907 (manufactured by Ciba Geigy Japan) 2.5 parts by mass After sequentially adding and mixing the above substances Ink 4 was prepared by filtration using a filter having an absolute filtration accuracy of 2 μm.

[Preparation of ink 5: the present invention]
Cyan pigment dispersion 1 (supra) 5 parts by mass Oil gelling agent (Exemplary compound OG-3) 50 parts by mass Photopolymerizable compound 1: Lauryl acrylate (monofunctional) 5 parts by mass Photopolymerizable compound 2: Ethylene oxide modified tri Methylolpropane triacrylate (trifunctional) 5 parts by mass Photopolymerizable compound 3: Caprolactam-modified dipentaerythritol hexaacrylate (hexafunctional) 17.5 parts by mass Photopolymerizable compound 4: tetraethylene glycol diacrylate (bifunctional)
12.5 parts by mass Polymerization initiator 1: Irgacure 184 (Nippon Ciba Geigy) 2.5 parts by mass Polymerization initiator 2: Irgacure 907 (Nippon Ciba Geigy) 2.5 parts by mass After mixing by heating to 80 ° C., the mixture was filtered using a filter having an absolute filtration accuracy of 2 μm to prepare ink 5.

[Preparation of inks 6 to 11: the present invention]
Inks 6 to 11 were prepared in the same manner as in the preparation of Ink 5, except that the type and amount of oil gelling agent were changed as shown in Table 1. In addition, with the change of the addition amount of the oil gelling agent, the addition amount of the photopolymerizable compounds 1 to 4 was adjusted at the same ratio (1: 1: 4: 3) so that the total amount became 100 parts by mass. .

[Preparation of Ink 12: Present Invention]
Color material: C.I. I. Pigment Blue 15: 3 (average particle diameter: 100 nm) 5 parts by mass Oil gelling agent (Exemplary Compound OG-3) 50 parts by mass Polymerizable Compound 1: Alicyclic Epoxy Compound (CEL2021P, manufactured by Daicel Chemical Industries)
15 parts by mass Polymerizable compound 2: Oxetane (OXT221, manufactured by Toagosei Co., Ltd.) 26.5 parts by mass Photopolymerization initiator 1: Iodonium salt (IBPF, manufactured by Sanwa Chemical) 2.5 parts by mass Thioxanthone (DETX, Nippon Kayaku) Manufactured) 1.0 part by mass The above substances were sequentially added, heated to 120 ° C. and mixed, and then filtered using a filter having an absolute filtration accuracy of 2 μm to prepare ink 12.

[Preparation of Ink 13: Present Invention]
Color material: C.I. I. Pigment Blue 15: 3 (average particle size: 100 nm) 5 parts by mass Oil gelling agent (Exemplary Compound OG-3) 3.2 parts by mass Polymerizable Compound 1: Alicyclic Epoxy Compound (CEL2021P, manufactured by Daicel Chemical Industries)
32 parts by mass Polymerizable compound 2: Oxetane (OXT221, manufactured by Toagosei Co., Ltd.) 56.3 parts by mass Photoinitiator 1: Iodonium salt (IBPF, manufactured by Sanwa Chemical) 2.5 parts by mass Thioxanthone (DETX, Nippon Kayaku) Manufactured) 1.0 part by mass The above substances were sequentially added, heated and mixed at 80 ° C., and then filtered using a filter having an absolute filtration accuracy of 2 μm to prepare ink 13.

  In the preparation of the inks 1 to 13, a thickener was appropriately added so as to obtain the viscosity shown in Table 1, and adjusted to a desired viscosity.

<Measurement of physical properties of each ink>
[Measurement of ink phase transition temperature]
Place each gel-like ink test piece on a melting point measuring machine (ATM-01 ATM-01), heat at a heating rate of 5 ° C / min or less, measure the temperature at which the test piece melts, and repeat this operation three times. The average value was calculated repeatedly, and the first decimal place was rounded off to obtain the ink phase transition temperature.

(Measurement of ink viscosity)
The ink viscosity was measured using a rheometer MCR300 (manufactured by Paar Physical) at a shear rate of 1000 seconds ⁻¹ at an ink phase transition temperature of + 5 ° C. determined by the above method. Moreover, about the ink which does not contain an oil gelling agent, it measured at 25 degreeC.

<< Inkjet image formation >>
A line head type ink jet recording apparatus having a piezo-type recording head and having the configuration shown in FIG. 2 is loaded with each of the inks prepared above, and plain paper (XEROX 4024 manufactured by XEROX) and art paper (manufactured by Mitsubishi Paper Industries) Cyan solid images were continuously printed on each recording medium of Tokuhishi art double-sided N) to obtain images 1 to 13. The ink supply system consists of an ink tank, a supply pipe, a front chamber ink tank just before the head, a pipe with a filter, and a recording head, and the head chamber to the recording head portion is insulated from the others and heated at 120 ° C. . The recording head was driven so that 4 pl multi-size dots could be ejected at a resolution of 1440 × 1440 dpi, and each ink was ejected continuously. After each ink has landed, an energy density of 140 W / cm from a high-pressure mercury lamp VZero085 (manufactured by INTEGRATION TECHNOLOGY), 10 seconds after the ink landed by a lamp unit arranged on the downstream side of the carriage in the conveyance direction of the recording medium, The ink was cured by irradiating ultraviolet rays at an illuminance of 20 mJ / cm ² (integrated light amount). In addition, the illumination intensity of the irradiation light source measured the integrated illumination intensity of 254 nm using UVPF-A1 by Iwasaki Electric Co., Ltd. Moreover, dpi as used in the field of this invention represents the number of dots per 2.54 cm.

<Evaluation of formed image>
The following evaluations were performed on images formed according to the above method.

[Evaluation of through-hole resistance]
The back side of the image sample printed using plain paper as a recording medium was visually observed, and the back-through resistance was evaluated according to the following criteria.

○: No ink bleed or show-through on the back side △: Ink bleed or show-through on the back side is slightly recognized, but acceptable quality for back side printing ×: Clear ink bleed on the back side , Show-through, and unsuitable quality for backside printing [Evaluation of image scratch resistance]
After printing each color solid image on each recording medium (plain paper and art paper), using scratch strength tester HEIDON-18 (manufactured by HEIDON), measuring needle using 0.8mmR sapphire needle, scratch strength Was measured. For the measurement, a 10 cm scratch test at a constant load was performed three times, and the limit load at which there was no scratched part on the recording medium was defined as the scratch strength, and the image rubbing property was evaluated from the measured values according to the following criteria.

○: Scratch strength is 200 g or more Δ: Scratch strength is 100 to less than 200 g ×: Scratch strength is less than 100 g [Evaluation of paper feed compatibility]
After 50 images were output continuously on each recording medium (plain paper and art paper) under the above conditions, observe whether there was a stop due to jamming, adhesion of foreign matter to the transport roller, and peeling of the formed image The sheet feeding compatibility was evaluated according to the following criteria.

○: Jamming did not occur even when continuous output was performed, and no foreign matter adhered to the transport roller or film peeling of the formed image occurred. Δ: Jamming occurred, transport roller even when continuous output was performed. Foreign matter adhesion to the surface was not recognized, but slight film peeling was observed in a small part of the formed image. X: Jamming occurred several times during continuous output. [Evaluation of light emission]
At the time of forming each inkjet image, the nozzle portion was cleaned, and the light emission property was evaluated according to the following criteria.

○: Good discharge from all nozzles after one cleaning. △: Nozzle clogged after one cleaning. Good discharge from all nozzles by the second cleaning. ×: Even after the second cleaning. Clogging is observed with one or more nozzles. Table 1 shows the results obtained as described above.

  As is apparent from the results in Table 1, the ink of the present invention containing an oil gelling agent and an actinic ray curable composition that is cured by actinic rays is used for the comparative example even when printed on plain paper. In addition, it is found that the formed image is excellent in abrasion resistance, and in addition, the paper feeding compatibility and the emission property are excellent when continuously printed. Furthermore, in the ink of the present invention, the ink having an ink phase transition temperature in the range of 40 to 80, the ink having an ink viscosity of 1 to 10 mPa · s, and the content of the oil gelling agent in the ink is 0.1 to 5 It can be seen that the effect is more exhibited with the ink of mass% or the ink having the melting point in the range of 40 to 90 ° C.

Example 2
In the formation of the inkjet image described in Example 1, using the ink 3 (comparative example) and the ink 5 (present invention) prepared in Example 1, the line head type inkjet recording apparatus (method) described in Example 1 1) and the serial head type ink jet recording apparatus (type 2) having the configuration shown in FIG. 1, the time from the ink droplet landing on the recording medium until the ultraviolet irradiation is changed as shown in Table 2 In the same manner as above, images 14 to 21 were prepared, and in the same manner as in Example 1, evaluation of back-through resistance, image scratch resistance, paper feed suitability, and output property was performed according to the following method. Muscle unevenness resistance (banding resistance) was evaluated, and the results obtained are shown in Table 2.

[Evaluation of muscle unevenness resistance]
After 50 images were output continuously, the occurrence of streak unevenness in the cyan solid image of the final sample was visually observed, and streak unevenness resistance was evaluated according to the following criteria.

○: No generation of muscle is observed △: Very weak muscle is observed, but is in a practically acceptable range ×: Obvious generation of muscle is recognized, and the quality is a problem in practical use. The results obtained are shown in Table 2.

  As is apparent from the results in Table 2, the ink of the present invention has little show-through even when printed on plain paper, and is excellent in image scratch resistance, paper feed compatibility, and emission properties, and in addition, has excellent unevenness resistance. It turns out that it is. Among them, printing using a line head type ink jet recording apparatus, or a level in which the time from the ink droplet landing on the recording medium to the ultraviolet irradiation is 5 seconds shows a more preferable result. I understand that.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Head carriage 3 Inkjet recording head 31 Ink ejection port 4 Irradiation means 5 Platen part 6 Guide member 7 Bellows structure P Recording medium

Claims (1)

  An inkjet image forming method for forming an image by ejecting an inkjet ink containing at least an oil gelling agent and an actinic ray curable composition curable by actinic rays from a inkjet recording head onto a recording medium. An ink jet image forming method comprising: forming an image by irradiating an actinic ray within 0.001 second to 5 seconds after an ink for ink has landed on the recording medium.

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