JP2003261799A - Active light-curable ink and ink jet recording method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active light-curable ink which has excellent curability and jetting stability and is optimized for obtaining high grade ink jet images, and to provide an ink jet recording method using the same. <P>SOLUTION: This ink jet recording method comprising jetting an active light-curable ink capable of being cured with the active light on a printing medium and then irradiating active light on the medium is characterized in that the active light-curable ink comprises a radical polymerization initiator, a polymerizable monomer, and a surface-coating agent. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an actinic ray curable ink and an ink jet recording method using the same,
More specifically, it relates to an actinic ray curable ink which is excellent in curability and emission stability and is optimized for obtaining a high quality inkjet image, and an inkjet recording method using the same.

[0002]

2. Description of the Related Art In recent years, the inkjet recording method has been simple and easy.
Since an image can be produced at low cost, it has been applied to various printing fields such as photography, various printing, marking, and special printing such as color filters. In particular, a recording device that emits and controls fine dots, and ink and ink absorption with improved color reproduction range, durability, emission suitability, coloring of color materials, and surface gloss have been dramatically improved. Using special paper,
It is also possible to obtain image quality comparable to silver salt photography. The improvement in image quality of today's inkjet recording system is achieved only when all of the recording device, ink, and special paper are provided.

However, in the ink jet system requiring a special paper, there are problems that the recording medium (hereinafter, also referred to as medium) is limited and the cost of the recording medium is increased. Therefore, many attempts have been made to record on a transfer medium different from dedicated paper by an inkjet method. Specifically, a phase change inkjet method using a solid wax ink at room temperature, a solvent inkjet method using an ink mainly composed of a quick-drying organic solvent, and a UV inkjet method in which cross-linking is performed by ultraviolet (UV) light after recording. Is.

Among them, the UV ink jet system has been attracting attention in recent years because it has a relatively low odor compared with the solvent type ink jet system and can perform recording on a recording medium which does not dry quickly and does not absorb ink. Fair 5-
54667, JP-A-6-200204, Special Table 200
No. 0-504778, a UV curable inkjet ink is disclosed.

However, in an image forming method using an actinic ray curable ink jet using ultraviolet rays or the like, it is an important factor that a high quality image can be formed even on a medium having no ink jet receiving layer, unlike the water based ink jet method. However, the conventional method causes problems such as bleeding and unevenness of the image when printing on a non-absorbent medium, especially the ink fixability on a medium with low surface tension is poor, and wrinkles occur when printing on a heat shrinkable material. It is not always possible to obtain sufficient performance in practice, such as the occurrence of curls and curls, and the current situation is that urgent improvement is required.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to obtain a high quality ink jet image which is excellent in curability and emission stability. An object is to provide an actinic ray curable ink and an inkjet recording method using the same.

[0007]

The above objects of the present invention have been achieved by the following constitutions.

1. An actinic ray curable ink used in an inkjet recording method in which an ink curable with an actinic ray is emitted to a printing medium and then irradiated with an actinic ray, wherein a radical polymerizable initiator, a polymerizable monomer and a surface coating agent are included. Actinic radiation curable ink.

2. In an inkjet recording method in which an actinic ray-curable ink that cures with an actinic ray is emitted to a printing medium and then irradiated with an actinic ray, the actinic ray-curable ink contains a radical polymerizable initiator, a polymerizable monomer and a surface coating agent. An ink jet recording method characterized by containing.

3. The surface energy of the print medium is 3
6. The ink jet recording method as described in the above item 2, which is 6 to 42 dyn / cm.

4. The surface energy of the print medium is 4
3. The ink jet recording method as described in the above item 2, which is 3 to 60 dyn / cm.

5. 5. The ink jet recording method according to any one of items 2 to 4, wherein the print medium is a non-absorbent recording medium.

6. 6. The inkjet recording method according to any one of items 2 to 5, wherein the print medium has a heat shrinkage rate at 80 ° C. of 5 to 50%.

7. The actinic radiation curable ink has landed,
The total ink film thickness after irradiation with actinic rays and curing is 2 to 2
It is 0 micrometer, The inkjet recording method of any one of said 2-6 characterized by the above-mentioned.

8. Appropriate amount of ejected ink liquid is 2 to 15p
7. The inkjet recording method according to any one of items 2 to 7, wherein the inkjet recording method is 1.

9. 9. The ink jet recording method according to any one of items 2 to 8, wherein after the actinic ray curable ink has landed, the actinic ray is irradiated for 0.001 to 1 second.

10. The active light has a peak illuminance in a wavelength range effective for curing of 1 mW / cm ² or more, 500 mW /
The inkjet recording method according to any one of items 2 to 9, wherein the inkjet recording method is less than cm ² .

11. The actinic ray has a peak illuminance of 500 mW / cm ² or more in a wavelength region effective for curing, 2000
The ink jet recording method according to any one of items 2 to 9, wherein the ink jet recording method is less than mW / cm ² .

As a result of earnest studies in view of the above problems, the inventor of the present invention ejects an ink curable with actinic rays onto a printing medium (hereinafter also referred to as a recording medium), and then irradiates the actinic rays with an ink jet recording method. As an actinic ray curable ink (hereinafter, abbreviated as the ink of the present invention) used for, a radically polymerizable initiator, a polymerizable monomer and a surface coating agent are contained, whereby a medium having low surface tension or a material having heat shrinkability However, it has been found that it is possible to obtain a level of fixability that can be practically used. Further, according to the inkjet recording method of the present invention,
Even in a medium having high surface tension, bleeding can be reduced and a high-definition image can be obtained.

Furthermore, since the ink of the present invention has optimized viscosity and surface tension and is free from polymerization inhibition by oxygen, good ejection properties and curability can be maintained even if the droplets are made small. As a result, a high resolution image can be formed. For the same reason, when the ink film thickness is reduced in order to utilize the texture of the medium to obtain gloss in the image, curing failure occurs. Since the ink of the present invention does not inhibit polymerization and has physical properties optimized for ejection, it is possible to obtain a high-quality image by combining it with a small droplet and a thin film.

Another advantage of the present invention is that the ink does not inhibit oxygen polymerization, so that good fixability can be achieved even under low illuminance. Further, since the ink has less reflected light from the medium and has excellent emission stability, it is possible to significantly improve nozzle clogging.

Further, it is possible to reduce contamination due to volatilization of the monomer and the initiator, which is a problem in the case of exposure with high illuminance, and it is possible to improve the bending suitability.

The details of the present invention will be described below. The actinic radiation curable ink of the present invention is characterized by containing a radically polymerizable initiator, a polymerizable monomer and a surface coating agent.

The surface coating agent in the present invention refers to a substance that forms a film on the surface when the ink is landed and then cured, and has an effect of suppressing the dissolution of oxygen into ink droplets. Examples thereof include surfactants and waxes.

As the surfactant which can be used in the present invention, known ones can be mentioned, for example, a silicone compound, a fluorine compound and the like. For example, a silicone type surfactant (eg, Silwet L720, F
Z2122, FZ2120, FZ2166, FZ217
1 (above, manufactured by Nippon Unicar Co., Ltd.), a silane coupling agent (for example, a silane coupling agent containing an unsaturated group), a carboxyl group, a mercapto group, an isocyano group, an amino group-containing coupling agent, and the like. To be As the fluorine-based compound, for example, a fluorine-based surfactant,
Acrylate, methacrylate, (polyoxyalkylene) acrylate or (polyoxyalkylene) methacrylate copolymer containing fluoroaliphatic group, JP-A-62-170950, JP-A-62-22614
3 and U.S. Pat. No. 3,787,351. Specifically, for example, Megafac F-171, 173, 177, 17
9, 142D, Defender MCF300, 312, 3
13 (above, manufactured by Dainippon Ink and Chemicals, Inc.) and Modibar F-100, 102, 110 (above, manufactured by NOF Corporation). Furthermore, JP-A-64-1814
Japanese Patent Publication No. 6-
No. 105351, Japanese Patent Publication No. 8-3630, and Fluorine-based surfactants described in JP-A-3-172849, JP-A-1-260055, JP-A-1-271.
The compounds described in JP-A No. 478 and JP-A No. 4-63802 can be preferably used. The water-repellent agent used for the water-repellent agent particles is preferably a fluorine-containing oligomer having hydrophilicity capable of forming a dispersed state at room temperature or an aqueous liquid, and specifically, Asahi Guard AG422, 428, 490, 530, 550, 71
0, 780, 880, 970, LS317 (all manufactured by Asahi Glass Co., Ltd.), TK Guard 505 (manufactured by Takamatsu Yushi Co., Ltd.), Dick Guard F-52S, F-70, F18,
F-90, F-90N, FS-90H (above, Dainippon Ink and Chemicals, Inc.) etc. can be mentioned. Among these, the side chain of the perfluoroalkyl group has 5 to 1 carbon atoms.
Water repellents having 5 carbon atoms are preferable, and water repellents having 6 to 12 carbon atoms are particularly preferable.

Further, for example, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl. Ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, tetra Oleic acid polyoxyethylene sorbit, polyethylene glycol monolaurate, polyethylene glycol Cole monostearate, polyethylene glycol monooleate, polyethylene glycol distearate, polyoxyethylene nonylphenyl ether formaldehyde condensate, oxyethyleneoxypropylene block copolymer, polyethylene glycol, nonionic activators such as tetraethylene glycol, lauryl alcohol Sodium salt of sulphate, sodium salt of octyl alcohol sulphate,
8 to 2 carbon atoms such as ammonium salt of lauryl alcohol sulfate and sodium secondary alkyl sulfate
2 higher alcohol sulfuric acid ester salts, for example, aliphatic alcohol sulfuric acid ester salts such as sodium salt of acetyl alcohol sulfuric acid ester, for example, sodium salt of dodecylbenzenesulfonic acid, sodium salt of isopropylnaphthalenesulfonic acid, and metanitrobenzenesulfonic acid. Alkylaryl sulfonates such as sodium salts, eg C ₁₇ H ₃₃ CON (CH ₃ ) C
Sulfonates of alkylamides such as H ₂ CH ₂ SO ₃ Na and the like, for example, anionic surfactants such as sulfonates of dibasic fatty acid esters such as sodium sulfosuccinate dioctyl ester and sodium sulfosuccinate dihexyl ester. , An alkylcarboxybetaine type, an alkylaminocarboxylic acid type, an alkylimidazoline type compound, or an amphoteric surfactant such as an organic boron compound disclosed in Japanese Patent Publication No. 1-57895.

Among the above compounds, the following surface active vinyl monomers can be preferably used.

[0028]

[Chemical 1]

Examples of waxes that can be used as the surface coating agent according to the present invention include carnauba wax and
Vegetable waxes such as wood wax, auricurie wax and espal wax; animal waxes such as beeswax, insect wax, shellac wax and whale wax; petroleum waxes such as paraffin wax, microcrystal wax, polyethylene wax, ester wax and acid wax;
In addition, waxes such as mineral waxes such as montan wax, ozokerite, ceresin and the like can be mentioned. Further, in addition to these waxes, higher fatty acids such as palmitic acid, stearic acid, margaric acid and behenic acid; palmityl alcohol, Higher alcohols such as stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol, eicosanol; higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate, myricyl stearate; acetamide, propionamide, palmitamide, Examples include amides such as stearic acid amide and amide wax; higher amines such as stearylamine, behenylamine and palmitylamine, and polymers such as ethylene-vinyl acetate polymer. 002-502443, the 2002-50
Amino functional latexes shown in 2442, acetoacetoxy functional and enamine functional polymers and the like are also suitably used.

The amount of the surface coating agent used in the present invention is 0.01 to 10% by mass based on the total mass of the ink.

The ink of the present invention contains a polymerizable monomer and a radical polymerizable initiator in addition to the above surface coating agent.

Various (meth) acrylate monomers can be used as the polymerizable monomer. For example, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomystil acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid. , Butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate,
Methoxy polyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid, lactone-modified flexible acrylate, Monofunctional monomers such as t-butylcyclohexyl acrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1, 6-hexanediol diacrylate,
1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, EO adduct of bisphenol A diacrylate, PO adduct of bisphenol A diacrylate, neopentyl glycol diacrylate hydroxypivalate, Bifunctional monomers such as polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxy. Triacrylate, cowprolactone modified trimethylolpropane tri Acrylate, pentaerythritol tetraacrylate, polyfunctional monomers having three or more functional such as caprolactam modified dipentaerythritol hexaacrylate and the like.

In addition, polymerizable oligomers can be blended in the same manner as the monomers. As the polymerizable oligomer,
Epoxy acrylate, aliphatic urethane acrylate,
Aromatic urethane acrylates, polyester acrylates, linear acrylic oligomers and the like can be mentioned.

In the present invention, it is particularly preferable to use a monofunctional, difunctional, trifunctional or higher polyfunctional monomer in combination as the polymerizable monomer. The monofunctional monomer has a large effect of reducing the shrinkage rate at the time of curing, has a low viscosity, and can easily obtain injection stability at the time of inkjet recording. The bifunctional monomer is preferably added because it has suitable sensitivity and excellent adhesion to various recording media. A trifunctional or higher polyfunctional monomer provides sensitivity and film strength after curing. By using these three in combination, curling and waviness due to curing shrinkage can be prevented,
Adhesion to a recording medium and high sensitivity are achieved.

The monofunctional monomer is 5 to 5 parts of the total ink composition.
40% by mass, 5 to 40% by mass of the bifunctional monomer, and 5 to 30% by mass of the polyfunctional monomer are preferably contained.
The monomer used in combination has a solubility parameter (SP
The combination of the difference between the maximum and minimum values is 1 or more,
It is preferable in terms of adhesion to various base materials and prevention of curling due to curing shrinkage. More preferably, it is 1.5 or more.

From the viewpoint of safety such as sensitization, skin irritation, eye irritation, mutagenicity and toxicity, among the above monomers, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate,
Decyl acrylate, isomystil acrylate, isostearyl acrylate, ethoxydiethylene glycol acrylate, methoxy polyethylene glycol acrylate, methoxypropylene glycol acrylate, isobornyl acrylate, lactone-modified flexible acrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene Glycol diacrylate, EO-modified trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxytriacrylate, cowprolactone-modified trimethylolpropane triacrylate, pentaerythritol ethoxytetraacrylate, cap Lactam-modified dipentaerythritol hexaacrylate are preferable.

Further, among these, stearyl acrylate, lauryl acrylate, isostearyl acrylate, ethoxydiethylene glycol acrylate, isobornyl acrylate, tetraethylene glycol diacrylate, EO-modified trimethylolpropane triacrylate, glycerine propoxytriacrylate, cowprolactone-modified tri Methylolpropane triacrylate and caprolactam-modified dipentaerythritol hexaacrylate are particularly preferred.

As the initiator, conventionally known initiators such as aryl alkyl ketone, oxime ketone, S-phenyl thiobenzoate, titanocene, aromatic ketone, thioxanthone, benzyl and quinone derivatives and ketocoumarins can be used. For more information on initiators, see "Applications and Markets of UV / EB Curing Technology" (CMC Publishing, edited by Yoneho Tabata / edited by Radtech Study Group). Among them, acyl phosphine oxide and acyl phosphonate have high sensitivity and their absorption is reduced by photocleavage of the initiator, so that they are suitable for internal curing in an ink image having a thickness of 5 to 15 μm per color as in the inkjet method. Especially effective. In particular,
Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide are preferable.

Further, like the above-mentioned monomers, 1-hydroxy-cyclohexyl-phenyl-ketone and 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropane-1 were selected in consideration of safety. -One, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur (R) 1173) Is preferably used. The preferable addition amount is 1 to 6% by mass, and preferably 2 to 5% by mass of the whole ink composition. In the present invention, it is preferable to divide the irradiation into two stages by changing the wavelength or intensity, and it is particularly preferable to use two or more kinds of initiators together.

In addition, when coloring the ink composition,
Add colorant. As the coloring material, a coloring material that can be dissolved or dispersed in the main component of the polymerizable compound can be used, but a pigment is preferable from the viewpoint of weather resistance. The following pigments can be used, but the pigments are not limited thereto. C. I Pigment Yellow-1,3,1
2, 13, 14, 17, 81, 83, 87, 95, 10
9, 42, C.I. I Pigment Orange-1
6,36,38, C.I. I Pigment Red-
5,22,38,48: 1,48: 2,48: 4,4
9: 1, 53: 1, 57: 1, 63: 1, 144, 14
6,185,101, C.I. I Pigment Vio
let-19, 23, C.I. I Pigment Blu
e-15: 1, 15: 3, 15: 4, 18, 60, 2
7,29, C.I. I Pigment Green-7,
36, C.I. I Pigment White-6,1
8, 21, C.I. I Pigment Black-7, 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 to disperse the pigment. It is also possible to add a dispersant when dispersing the pigment. It is preferable to use a polymer dispersant as the dispersant. As the polymer dispersant, Solsp manufactured by Zeneca is used.
The erse series can be mentioned. Also, as a dispersion aid,
It is also possible to use synergists according to various pigments. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. The dispersion medium is a solvent or a polymerizable compound, but the radiation-curable ink used in the present invention is preferably solvent-free because it reacts and cures immediately after the ink has landed. If the solvent remains in the cured image, problems of solvent resistance deterioration and residual solvent VOC occur. Therefore, it is preferable in view of dispersion suitability that the dispersion medium is selected from a polymerizable compound, not a solvent, and a monomer having the lowest viscosity among them.

The dispersion has an average particle size of 0.08 to 0.5 μm.
And the maximum particle size is 0.3 to 10 μm,
A pigment, a dispersant, so that the thickness is preferably 0.3 to 3 μm,
Set the dispersion medium selection, dispersion conditions, and filtration conditions. By controlling the particle size, clogging of the head nozzle can be suppressed, and the ink storage stability, ink transparency, and curing sensitivity can be maintained. Color material is 1% by mass to 10% of the total ink
An addition amount of mass% is preferable.

A polymerization inhibitor may be added in an amount of 200 to 20,000 ppm in order to improve the storage stability of the ink.
Since it is preferable that the ultraviolet curable ink is heated to lower the viscosity and then ejected, it is preferable to add a polymerization inhibitor in order to prevent head clogging due to thermal polymerization.

Further, due to the light shielding effect of the ink coloring material, as a means for preventing sensitivity, it is also possible to combine a cationically polymerizable monomer having a long initiator life with an initiator to form a radical / cation hybrid type curable ink. .

The ink is preferably 7 to 30 mPa · s, more preferably 7 at a temperature at the time of ejection in consideration of ejection property.
The composition ratio is determined so as to be ˜20 mPa · s. 2
The ink viscosity at 5 ° C. is preferably 35 mPa · s or more. By increasing the viscosity at room temperature, it is possible to prevent ink from penetrating into porous recording media, reduce uncured monomer, and reduce odor. Also, when printing on non-absorption media, dots when landing Bleeding can be suppressed and the image quality is improved. Surface tension is preferably 200-300
μN / cm, more preferably 230 to 280 μN / cm
Is.

The recording medium used in the present invention is not particularly limited, but a preferable recording medium is a so-called non-absorptive material, such as a fibrous material such as paper for absorbing ink, or a support. It means that an ink absorption layer is provided on the disk and a resin that absorbs ink and swells is used, or that an ink absorption layer that forms voids in the layer by using a filler or resin particles is not provided. Specific examples include paper coated with a resin on the surface, plastic film, plastic sheet, metal, ceramic, glass, and the like.

The material of the plastic sheet or film is, for example, 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. Further, these copolymers and blends, and further crosslinked products can be used.

In the present invention, the surface energy of the recording medium is 36 to 42 dyn / cm, or the surface energy of the recording medium is 43 to 60 dyn / cm.
Is preferred. The surface energy (also referred to as wettability) referred to in the present invention can be evaluated by using the wet tension test method for plastic films and sheets according to JIS-K-6768.

The method for obtaining the recording medium having the surface energy specified in the present invention can be achieved by pretreating the recording medium. As the pretreatment, an easy contact layer for improving the wettability may be provided, and for example, solvent treatment, flame treatment, corona treatment, plasma treatment or the like can be performed. Further, when performing corona treatment or plasma treatment, it is preferable that the time from pretreatment to printing is short.

In the present invention, the recording medium is 80
It is preferable that the heat shrinkage at 5 ° C. is 5 to 50%.

The heat-shrinkable support used in the present invention is a support which shrinks in the longitudinal direction or the transverse direction by heat,
Various ordinary plastics and films thereof can be used. PET (polyethylene terephthalate) film, OPS (stretched polystyrene) film, OPP (stretched polypropylene) film
Film, ONy (stretched nylon) film, PVC
(Polyvinyl chloride) film, PE (polyethylene) film, and TAC (triacetyl cellulose) film can be used. Other plastics include polycarbonate, acrylic resin, ABS, polyacetal, P
VA, rubber, etc. can be used. Further, it is also applicable to metals and glasses.

Among these supports, the heat shrinkage in the longitudinal or transverse direction at 80 ° C. (evaluation condition: 70 ° C.,
A film having a hot water immersion time of 10 seconds) of 5 to 50% is preferable.

Next, details of the ink jet recording method of the present invention will be described. In the inkjet recording method of the present invention, the ink is ejected onto the recording medium by an inkjet head to draw an image, and then the active ray such as ultraviolet rays is irradiated to cure the ink.

The ink ejection conditions are 40 inks.
From the viewpoint of injection stability, it is preferable to heat the ink to -80 ° C to reduce the viscosity of the ink and eject the ink. Since the radiation-curable ink generally has a higher viscosity than the water-based ink, the fluctuation range of viscosity due to temperature fluctuation is large. Since the viscosity variation directly affects the droplet size and the droplet ejection speed and deteriorates the image quality, it is necessary to keep the ink temperature as constant as possible.

As the ink-jet head used in the present invention (hereinafter, also simply referred to as a head), a known one can be used, and a continuous type or a dot-on-demand type can be used. Among the dot-on-demand types, the thermal head is used for ejection, and therefore, Japanese Patent Application Laid-Open No. 9-3
A type having an operating valve as described in 23420 is preferred. In the piezo head, for example, European Patent A
Heads described in, for example, 277,703 and European Patent A278,590 can be used. The head preferably has a temperature control function so that the temperature of the ink can be controlled. It is preferable to set the emission temperature so that the viscosity at the time of ejection is 5 to 25 mPa · s and control the ink temperature so that the fluctuation range of the viscosity is within ± 5%. The drive frequency is preferably 5 to 500 kHz.

In the present invention, the amount of ink droplets is preferably 2 to 20 pl in order to obtain a high-definition image. Since the ink of the present invention has good ejection characteristics, it is possible to obtain a good image without causing nozzle clogging, dot bending, satellites, etc. even if the amount of droplets is small.

Further, in the present invention, in order to obtain a high-quality glossy image, the total ink film thickness printed is 2 to 2
It is preferably 0 μm.

Specific examples of the ink jet head that can be used in the present invention will be described below.

FIG. 1 is a sectional view showing an example of an ink jet head used in the ink jet recording method of the present invention.

FIG. 1A is a sectional view of the ink jet head, and FIG. 1B is an enlarged view taken along the line AA of FIG. 1A. In the figure, 1 is a substrate, 2 is a piezoelectric element, 3 is a flow path plate, 3a is an ink flow path, 3b is a wall portion, 4 is a common liquid chamber constituent member, 4a is a common liquid chamber, 5 is an ink supply pipe, 6 Is a nozzle plate, 6a is a nozzle, 7 is a drive circuit printed board (PCB), 8 is a lead wire, 9 is a drive electrode, 10 is a groove, 11 is a protective plate, 12 is a fluid resistance, 13 and 14 are electrodes, 15 Is an upper partition wall, 16 is a heater, 17 is a heater power source, 18 is a heat transfer member, and 19 is a recording head.

In the integrated head, the electrodes 13,
The laminated piezoelectric element 2 having 14 is grooved in the direction of the flow path 3a corresponding to the flow path 3a, and is divided into the groove 10, the driving piezoelectric element 2b, and the non-driving piezoelectric element 2a. Groove 1
Filler is enclosed in 0. The flow path plate 3 is bonded to the grooved piezoelectric element 2 through the upper partition wall 15. That is, the upper partition 15 is formed of the non-driving piezoelectric element 2.
It is supported by a and a wall portion 3b that separates the adjacent flow path. The width of the driving piezoelectric element 2b is slightly narrower than the width of the flow path 3a,
When a pulse-shaped signal voltage is applied to the driving piezoelectric element 2b selected by the driving circuit on the driving circuit printed board (PCB), the driving piezoelectric element 2b changes in the thickness direction and the flow path 3a passes through the upper partition wall 15. Changes, and as a result, ink droplets are ejected from the nozzles 6a of the nozzle plate 6.

Heaters 16 are adhered to the flow path plate 3 via heat transfer members 18, respectively. The heat transfer member 18 is provided around the nozzle surface. Heat transfer member 18
Aims to efficiently transfer the heat from the heater 16 to the flow path plate 3 and to convey the heat from the heater 16 to the vicinity of the nozzle surface to warm the air in the vicinity of the nozzle surface. Therefore, the thermal conductivity is good. Material is used. Examples of preferable materials include metals such as aluminum, iron, nickel, copper and stainless steel, and ceramics such as SiC, BeO and AlN.

When the piezoelectric element is driven, the piezoelectric element is displaced in the direction perpendicular to the longitudinal direction of the flow path, the volume of the flow path is changed, and the change in volume causes ink droplets to be ejected from the nozzle. The piezoelectric element is constantly given a signal to hold it so that the volume of the flow channel shrinks, and after the displacement of the selected flow channel in the direction of increasing the volume of the flow channel, the displacement of the volume of the flow channel is reduced again. By applying a given pulse signal, ink is ejected as ink droplets from the nozzle corresponding to the flow path.

FIG. 2 is a schematic view showing an example of an ink jet head section and a nozzle plate.

In FIG. 2, FIG. 2A is a sectional view of the head portion,
FIG. 2B is a plan view of the nozzle plate. 2 in the figure
Reference numeral 0 is a recording medium, 21 is an ink droplet, 22a to 22j are nozzles, and 23 is a platen. The ink droplet 21 ejected from the nozzle 22 flies toward the recording medium 20 and adheres thereto.

In the ink jet recording method of the present invention, the ink emitted onto the recording medium is irradiated with actinic rays to be cured.

The light source used in the irradiation means according to the present invention is an actinic ray such as a near infrared ray, a visible ray, an ultraviolet ray or an electron beam, and a light source having an emission wavelength in the ultraviolet region is particularly preferable. Is a light source having a main wavelength of 300 to 400 nm, and includes, for example, a low pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, an excimer lamp,
Xenon lamp, halogen lamp, fluorescent lamp, cold cathode tube,
Examples include electrodeless UV lamps, lasers, LEDs and the like.

In the present invention, as the irradiation means, an actinic ray can be irradiated from the light source to the substrate. For example,
As disclosed in JP-A-60-132767, a method of moving an ultraviolet lamp together with a recording head for scanning a recording medium, and a technique disclosed in US Pat. No. 6,145,979, A method is known in which an ultraviolet light source installed at a position distant from the recording head guides the ultraviolet light to the side of the recording head using an optical system such as an optical fiber, a collimator, or a mirror. In addition, Japanese Patent Application No. 2001-35021
It is also possible to provide a linear light source across the width direction from the upper part of the recording head as shown in FIG. In the present invention, the illuminance means the total irradiation energy of actinic rays, and the irradiation timing means the time from the landing to the start of irradiation. The peak wavelength is a wavelength having the largest irradiation energy among the active rays of 450 nm or less, and the peak illuminance indicates the illuminance at the peak wavelength. Further, the irradiation time is a time during which an active ray of 1/10 or more of the maximum illuminance is irradiated in the irradiation part. In the present invention, the spectral illuminance is spectrophotometer USR-40D / V manufactured by Ushio Inc.
Then, the measurement pitch is measured at 10 nm.

As another irradiation means that can be used in the present invention, active light irradiation can be performed on the substrate by an application method of the first irradiation means. For example, applying a method of moving an ultraviolet lamp together with a recording head to irradiate an active ray while mounting a light source on a carriage and operating a recording medium, or recording from a fixed ultraviolet light source with an optical system such as an optical fiber, collimator, or mirror. It is also possible to use a method of inducing ultraviolet rays to the side of the head. It is also possible to provide a linear light source that illuminates the entire width of the base material. In the irradiating means according to the present invention, it is also possible to disperse the light emitted from one light source by using a filter, a mirror or the like and separately irradiate it into the first and second irradiating means.

In the present invention, it is preferable to irradiate the actinic ray within 0.001 to 1 second after the actinic ray curable ink has landed. Irradiation interval of irradiation rays is 0.001
If the time is shorter than 2 seconds, the distance between the nozzle and the light source becomes too short, the sublimate generated by curing may contaminate the head, or the nozzle may be clogged by light sneaking in, which is not preferable. If it is longer than 1 second, the effect of the present invention cannot be sufficiently obtained.

Further, as one of preferred embodiments of the method of irradiating with actinic rays in the present invention, the peak illuminance of actinic rays in the wavelength region effective for curing is 1 mW / cm ² or more, 500.
It is less than mW / cm ² .

As another preferred embodiment of the actinic ray irradiation method of the present invention, the actinic ray has a peak illuminance in the wavelength region effective for curing of 500 mW / cm ² or more, 20 or more.
It is less than 00 mW / cm ² .

The printing method used in the present invention is preferably an ink jet method in which small ink droplets are ejected from multiple nozzles. FIG. 3 shows an example of an inkjet printing method that can be preferably used in the present invention.

In FIG. 3, a) in FIG. 3 is a method (line head method) in which the head is arranged in the width direction of the printing portion and printing is performed while the recording medium is conveyed, and in b) in FIG. A method of printing while moving in the sub-scanning direction (flat head method), a method of c) in FIG. 3 is a method of printing while the head scans in the width direction on the recording medium (capstan method), Either method can be used.

[0074]

EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.

Example 1 <Preparation of Ink Set A> [Preparation of Each Pigment Dispersion] The following compositions were blended by a pressure kneader, and then kneaded and dispersed by a three-roll mill to obtain each pigment dispersion. It was In these preparations, the temperature was controlled appropriately so as not to exceed 80 ° C.

(Black pigment dispersion: K1) Pigment Black 7 (carbon black) 70 parts by mass Styrene / acrylic acid ester copolymer (acid value 1 or less) 10 parts by mass Phenoxy polyethylene glycol acrylate 20 parts by mass Polymerization inhibitor (Sumitomo Chemical, Sumilizer GS) 0.1 parts by mass (Yellow pigment dispersion: Y1) Pigment Yellow 93 70 parts by mass Nonionic dispersant 10 parts by mass Phenoxy polyethylene glycol acrylate 20 parts by mass Polymerization inhibitor (Sumitomo Chemical, Sumilizer GS) 0.1 parts by mass (magenta pigment dispersion: M1) Pigment Violet 19 70 parts by mass Nonionic dispersant 10 parts by mass Phenoxy polyethylene glycol acrylate 20 parts by mass Polymerization inhibitor (Sumitomo Chemical, Sumilize r GS) 0.1 parts by mass (cyan pigment dispersion: C1) Pigment Blue 15: 3 70 parts by mass Nonionic dispersant 10 parts by mass Phenoxy polyethylene glycol acrylate 20 parts by mass Polymerization inhibitor (Sumitizer GS, Sumilizer GS) 0 1 parts by mass [Preparation of Ink for Each Color] Ink set A was prepared by using the above pigment dispersions to prepare each color ink having the constitution shown in Table 1.

To prepare each color ink, all the materials other than the pigment dispersion were mixed in advance, and after confirming that they were sufficiently dissolved, the temperature was raised to 50 ° C., and then each pigment dispersion was added little by little, and then the dissolver was added. After thoroughly stirring using
It filtered with the filter of m. Also, as pre-processing, 1
Pre-filtration of 0 μm was performed. It should be noted that in the filtration step, the occurrence of pressure loss was small and a sufficient filtration rate was obtained.

Next, each ink was heated to 50 ° C. and decompressed while stirring to remove dissolved air and water, thereby preparing each color ink. The viscosity of each prepared color ink at 25 ° C. is 12 to 22 mP.
a · s, the surface tension was 24 to 30 mN / m, and the average particle size of the pigment particles was 0.08 to 0.3 μm.

[0079]

[Table 1]

The details of each additive shown in Table 1 are as follows. DPCA60: KAYARAD DPC manufactured by Nippon Kayaku Co., Ltd.
A (caprolactam-modified dipentaerythritol hexaacrylate) TEGDA: Osaka Organic Co., viscoat # 335HP
(Tetraethylene glycol diacrylate) PO-A: Kyoeisha Chemical Co., Ltd., light acrylate PO-
A (phenoxyethyl acrylate) I369: Ciba Specialty Chemicals, Ir
gacure369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1

[0081]

[Chemical 2]

<< Preparation of Ink Set B >> [Preparation of Pigment Dispersion] A pigment dispersion having the following composition was prepared. The average particle size was dispersed so as to be 0.2 to 0.3 μm.

(Black pigment dispersion: K2) Pigment Black 7 20 parts by mass Polymeric dispersant (Solsperse manufactured by Zeneca) 5 parts by mass Stearyl acrylate 75 parts by mass (Yellow pigment dispersion: Y2) Pigment Yellow 12 10 parts by mass High Molecular Dispersant (Solsperse manufactured by Zeneca) 5 parts by mass Stearyl Acrylate 85 parts by mass (Magenta Pigment Dispersion: M2) Pigment Red 57: 1 15 parts by mass Polymer Dispersant (Solsperse manufactured by Zeneca) 5 parts by mass Stearyl Acrylate 80 parts by mass Parts (cyan pigment dispersion: C2) Pigment Blue 15: 3 20 parts by mass Polymeric dispersant (Solsperse manufactured by Zeneca) 5 parts by mass Stearyl acrylate 75 parts by mass [Preparation of inks of each color] Each dispersion described above It used, to prepare a ink having the following formulation, which was used as an ink set B.

(Black Ink 2) Black pigment dispersion: K2 15 parts by mass Stearyl acrylate 65 parts by mass Tetraethylene glycol diacrylate (bifunctional) 10 parts by mass Caprolactam modified dipentaerythritol hexaacrylate (6 functional) 5 parts by mass Initiator (Ciba, Irgacure 184) 5 parts by mass (Yellow Ink 2) Yellow pigment dispersion: Y2 20 parts by mass Stearyl acrylate 60 parts by mass Tetraethylene glycol diacrylate (bifunctional) 10 parts by mass Caprolactam modified dipentaerythritol hexaacrylate ( Hexafunctional) 5 parts by mass Initiator (manufactured by Ciba, Irgacure 184) 5 parts by mass (Magenta ink 2) Magenta pigment dispersion: M2 20 parts by mass Stearyl acrylate 60 parts by mass Tetraethyl Lenglycol diacrylate (2 functional) 10 parts by mass Caprolactam modified dipentaerythritol hexaacrylate (6 functional) 5 parts by mass Initiator (manufactured by Ciba, Irgacure 184) 5 parts by mass (Cyan ink 2) Cyan pigment dispersion: C215 Parts by mass Stearyl acrylate 65 parts by mass Tetraethylene glycol diacrylate (bifunctional) 10 parts by mass Caprolactam modified dipentaerythritol hexaacrylate (6 functional) 5 parts by mass Initiator (manufactured by Ciba, Irgacure 184) 5 parts by mass or more for each color ink Was filtered with a filter having an absolute filtration accuracy of 2 μm to obtain an ink. The viscosity of the ink at 25 ° C. is 80 to 150 mPa · s, and the viscosity at 70 ° C. is 1
Surface tension at 0 to 20 mPa · s and 25 ° C is 240
˜280 μN / cm.

<< Printing of Inkjet Image >> [Printer] The printer uses the method described in the line head method (a in FIG. 3) (hereinafter referred to as method A), and the printer head and the engine are shown in FIG. ) And (b) were used, and the positions of the printer head and the irradiation light source were appropriately adjusted so that the irradiation timing (irradiation interval) after landing shown in Table 2 was reached.

More specifically, the printer head is as shown in FIG.
The ink supply system described in (a) and (b) is used, and the ink supply system includes an original tank, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo type inkjet head. The part was insulated and heated. The temperature sensor was provided in the vicinity of each of the nozzles of the ink supply tank and the inkjet head, and the temperature was controlled so that the nozzle portion was always set temperature ± 2 ° C. The nozzle pitch was 300 dpi, and 512 nozzles were provided for each head. Further, the nozzle diameter is adjusted to 10 to 30 μm, the injection temperature is adjusted to 20 to 150 ° C., and the driving voltage is adjusted to 5 to 30 V so that the droplet amount and the ink film thickness shown in Table 2 are obtained. The irradiation time of the light source was also adjusted within the range of 0.01 to 20 seconds. The term "dpi" used in the present invention is 2.54.
Represents the number of dots per cm, and the printed image density is 3
It was set to 00 × 300 dpi.

Using the above image forming apparatus, as shown in Table 2, ink type, ink droplet amount, ink film thickness, irradiation light source and its illuminance, irradiation timing after irradiation (irradiation interval),
Combined with print recording media of each surface energy, 1
Images 101 to 107 were created by printing solid patches of secondary colors (Y, M, C, K) and secondary colors (B, G, R).

Details of the recording medium and the irradiation light source shown in Table 2 are as follows. (Recording medium) OPP: Stretched polypropylene film PE: Polyethylene film (irradiation light source) Cold cathode fluorescent lamp: Hivec's main wavelength 365 nm UV fluorescent lamp: NIPPO ELECTRIC's main wavelength 365 nm Metal halide: Nihon Battery's main wavelength 365 nm << Image Evaluation >> Images 101-created as described above
For No. 107, solid patches of primary colors (Y, M, C, K) and secondary colors (B, G, R) were visually observed, banding was evaluated according to the following criteria, and the obtained results are displayed. Two
Shown in.

5: No banding 4: 1 Slight banding on one patch 3: Slight banding on two patches 2: Strong banding on one patch 1: Weak banding on three or more patches 0.2 Banding resistant to more than one patch In the above evaluation, 3 to 5 was judged to be a practically acceptable range.

[0090]

[Table 2]

As is clear from Table 2, the image produced using the ink set A of the present invention has excellent banding resistance, even when printed on various recording media, as compared with the comparative example. I understand.

Example 2 << Printing of Inkjet Image >> In the inkjet image printing of Example 1, as a printer, the method described in the flat head system (b of FIG. 3) instead of the line head system (system A), Hereinafter, the method will be referred to as method B), and as shown in Table 3, the ink type, the ink droplet amount, the ink film thickness, the irradiation light source and its illuminance, the irradiation timing, and the print recording medium of each surface energy are combined. Images 201 to 208 are created by printing blank characters of different sizes in solid patches of primary colors (Y, M, C, K), secondary colors (B, G, R) and 4-color solid patches. did.

The details of the recording medium shown in Table 3 are as follows. Plasma OPP: Stretched polypropylene film surface subjected to atmospheric pressure plasma treatment Corona PE: Polyethylene film surface subjected to corona discharge treatment PET: Polyethylene terephthalate film << Evaluation of image >> Images 201 to 1 created as described above
For 208, banding was evaluated by the method described in Example 1, and bleeding was evaluated according to the following method.

(Evaluation of bleeding) In a four-color solid patch,
The image on which the printed characters with different points were printed was visually observed, and the number of points of characters that could be satisfactorily reproduced without bleeding was measured.

Table 3 shows the results obtained as described above.

[0096]

[Table 3]

As is clear from Table 3, the images printed on various recording media by the flat head type printer using the ink of the present invention showed less bleeding and banding than the comparative examples. I understand that.

Example 3 << Printing of Inkjet Image >> In the printing of the inkjet image of Example 1, as a printer, the method described in the capstan system (c of FIG. 3) instead of the line head system (system A), (Hereinafter referred to as method C), and as shown in Table 4, the ink type, the ink droplet amount, the ink film thickness, the irradiation light source and its illuminance, the irradiation timing, and the print recording medium type are combined to obtain ISO / JIS-SCID
N4 was printed to create images 301 to 307.

Details of the recording media shown in Table 4 are as follows. PVC: Hishilex 302-S (Mitsubishi resin thickness 50 μm, 80 ° C heat shrinkage 36% (TD)) OPS: DXL film 219V-01 (Mitsubishi resin 80 ° C heat shrinkage 25% (TD)) << Image Evaluation >> Image 301-created as described above
Regarding 307, the thermal shrinkage, curl and stretchability of the recording medium were evaluated according to the following methods, and the obtained results are shown in Table 4.

(Measurement of thermal shrinkage of recording medium) Each recording medium used was cut into a size of 100 mm in length and 10 mm in width, and the vertical and horizontal lengths (mm) before and after heating at 80 ° C. were measured. After being left in an atmosphere of 23 ° C. and 55% RH for 24 hours, it was accurately measured, and the heat shrinkage rate was measured by the following formula.

Thermal shrinkage (%) = [{(length before heat treatment)-(length after heat treatment)} / (length before measurement)] ×
100 (Evaluation of curl and stretchability) The curl and stretchability when each image was output were evaluated according to the following criteria.

◯: No curl or expansion / contraction at all Δ: Slight expansion / contraction is observed and weak curl occurs ×: Large contraction occurs and strong curl occurs, which is a problematic quality for practical use.

[0103]

[Table 4]

As is clear from Table 4, an image printed on a recording medium having a different thermal contraction rate with the ink of the present invention by a capstan type printer is superior in curl characteristic to the comparative example. I understand.

Example 4 According to the method described in Example 3, as shown in Table 5, the ink type, the ink droplet amount, the ink film thickness, the irradiation light source and its illuminance, the irradiation timing, the print recording medium type, and the like. , The primary colors (Y, M, C, K) and the secondary colors (B,
G, R) solid patch and ISO / JIS-SCID N
4 was printed to create images 401 to 417.

The details of the recording medium shown in Table 5 are as follows. Fine paper: OK Prince fine paper 127.5 g / m ² (manufactured by Oji Paper Co., Ltd.) Nonwoven fabric: OIKOS (manufactured by Nisshinbo Co., Ltd.) Further, the details of the irradiation light source other than those described above are as follows.

High pressure mercury lamp: Main wavelength 3 manufactured by Nippon Battery Co., Ltd.
66 nm << Evaluation of image >> Image 401 created as described above
For 417, the bending resistance and the image unevenness were evaluated according to the following methods.

(Evaluation of Bending Resistance) With respect to the prepared four-color solid patch image as the primary color, the bending resistance was evaluated according to the following method 5: No change was observed in the ink film during bending 4: Color change occurs in the bent part, but no cracks are observed. 3: There is a slight crack in the bent part, but there is no problem in practical use. 2: When bent, the ink film peels from the cracked part. ,
There is a problem in practical use 1: Cracks and dropout of the ink film occurred just by bending it. It was judged that there was no problem if the evaluation rank was 3 to 5.

(Evaluation of image irregularity) Each IS prepared above
Regarding the O4 / JIS-SCID N4 image, the unevenness feeling in the low density portion and the high density portion was evaluated according to the following criteria.

[0110] ○: No unevenness even when touched by hand △: Slightly uneven X: The unevenness is large and there is a problem in practical use Table 5 shows the results obtained as described above.

[0111]

[Table 5]

As is clear from Table 5, the images printed on various recording media with the ink of the present invention are superior in bending resistance and have less unevenness difference than the comparative examples.

Example 5 According to the method described in Examples 1 and 3, as shown in Table 6, ink type, printer type, ink droplet amount, ink film thickness, irradiation light source and its illuminance, irradiation timing, The primary colors (Y, M, C,
K) Solid patches of secondary colors (B, G, R) and characters with different points were printed to create images 501 to 518.

<< Evaluation of Image >> Characteristic reproducibility of images 501 to 518 created as described above is evaluated according to the following method, and ink droplet bending (flying linearity) at the time of printing each image. Was evaluated.

(Evaluation of Deflection of Ink Droplet) After printing a grid at 1 mm intervals and continuously printing 100 m ² of the grid,
Similar grids with 1 mm intervals were printed in a range of 3 × 3 cm, and the reproducibility of positional accuracy was evaluated according to the following criteria.

◯: The grid is printed at an accurate position Δ: Visually recognizable misalignment The number of dots in the grid is 5% or less ×: The misalignment of the grid printing position is large, which is a practical problem. Characters with certain quality (evaluation of character reproducibility) were printed with different points, and the points of characters that could be reproduced without being crushed or cut were recorded for the image.

Table 6 shows the results obtained as described above.

[0118]

[Table 6]

As is apparent from Table 6, the images printed on various recording media with the ink of the present invention and the ink jet recording method have less bending of droplets and excellent character reproducibility as compared with Comparative Examples. I know that

Example 6 According to the method described in Examples 1 and 3, as shown in Table 7, ink type, printer type, ink droplet amount, ink film thickness, irradiation light source and its illuminance, irradiation timing, Images 601 to 617 were created by printing the following images in combination with the types of print recording media.

<< Evaluation of Image >> With respect to the images 601 to 617 produced as described above, the brightness was evaluated and the clogging of the inkjet nozzle at the time of printing each image was evaluated according to the following method.

(Evaluation of Lightness) As an output image, the reflection density is 1. When the emission amount ratio of Y ink and M ink is 1: 1.
A red patch was prepared so as to have a color density of 6, and its lightness (L ^* ) was measured with a color analyzer (CMS- manufactured by Murakami Color Co., Ltd.).
1200).

(Evaluation of Nozzle Clogging) With respect to 512 nozzles after printing an image of 1000 m ² , the presence or absence of nozzle clogging was visually observed and judged according to the following criteria.

[0124] 5: No nozzle clogging 4: 1% of nozzles are clogged 3: Clogs occur in 1 to less than 2% of nozzles 2: Clogging occurs in 2 to less than 5% of nozzles 1: Clogging occurs in 5% or more of nozzles If it was 3 to 5, it was judged as a practically feasible level.

Table 7 shows the results obtained as described above.

[0126]

[Table 7]

As is clear from Table 7, the images printed on various recording media with the ink of the present invention and the ink jet recording method have higher lightness and less clogging at the ink head nozzle than the comparative examples. I understand.

Example 7 According to the method described in Example 3, as shown in Table 8, ink type, printer type, ink droplet amount, ink film thickness, irradiation light source and its illuminance, irradiation timing, print recording. In combination with the media type, the primary colors (Y, M, C,
K) print solid patches of secondary colors (B, G, R),
Images 701-717 were created.

<< Evaluation of Image >> With respect to the images 701 to 717 produced as described above, the glossiness and the adhesiveness of the solid image portion were evaluated according to the following methods.

(Measurement of Glossiness of Solid Image Area) Glossiness was measured according to the method (60 degree specular glossiness (Gs 60 °)) defined in JIS-Z-8741, and the glossiness was 20. If it is above, it was judged as a practically feasible level.

(Evaluation of Adhesiveness) The solid image surface was cut with a razor such that 6 cuts were made so that the recording medium could not reach the recording medium, and 25 squares were formed. After a cellophane tape (R) having a width of 25 mm was adhered and strongly bonded onto this, the pieces were quickly peeled off at a peeling angle of 90 °, the number of squares peeled was measured, and the ranks A to E were divided according to the following criteria. It was

In the following ranks, A and B are practically acceptable. A: All the squares were not peeled off B: The number of peeled squares was 1 to 3 C: The number of peeled squares was 4 to 10 D: The number of peeled squares was 11 to 25 E: Yes, the number of peeled squares was 26 or more. The results obtained as described above are shown in Table 8.

[0133]

[Table 8]

As is clear from Table 8, the images printed on various recording media with the ink of the present invention are superior in glossiness to the comparative examples, and the formed images have good adhesiveness. I understand.

Example 8 According to the method described in Example 3, as shown in Table 9, ink type, printer type, ink droplet amount, ink film thickness, irradiation light source (metal halide) and its illuminance (100).
0 mW / cm ² ), irradiation timing, and print recording medium type are combined to print a solid patch of a primary color (Y, M, C, K) and a secondary color (B, G, R). ~
817 was created.

<Evaluation of Image> The images 801 to 817 produced as described above were evaluated for scratch strength and image storability according to the following methods.

(Measurement of Scratch Strength) The surface of each solid patch was scratched with a scratch strength tester (HEIDON-18 HE).
(Manufactured by IDON Co., Ltd.), a measuring needle is a sapphire needle of 1.0 mmR, scanning is performed while changing a load of 0 to 200 g, and a load value when a scratch is generated is measured, and an average value of 7 colors is obtained. I asked.

(Evaluation of Image Preservability) The image density of each solid patch of the primary color was measured when it was left outdoors for 3 months.
The image remaining ratio was calculated when the image density before standing was set to 100, and the average value of the image remaining ratios of the four colors was used as a measure of image storability.

Table 9 shows the results obtained as described above.

[0140]

[Table 9]

As is clear from Table 9, the images printed on various recording media with the ink of the present invention have excellent image strength (scratch strength) and good image storability as compared with Comparative Examples. I understand.

[0142]

According to the present invention, it is possible to provide an actinic ray curable ink which is excellent in curability and emission stability and is optimized for obtaining a high quality ink jet image, and an ink jet recording method using the same. It was

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an inkjet head used in an inkjet recording method of the present invention.

FIG. 2 is a schematic diagram showing an example of an inkjet head unit and a nozzle plate used in the inkjet recording method of the present invention.

FIG. 3 is a schematic diagram showing an example of an inkjet printing method that can be used in the present invention.

[Explanation of symbols]

1 substrate 2 Piezoelectric element 3 flow path plates 3a ink flow path 3b wall 4 Common liquid chamber components 4a Common liquid chamber 5 Ink supply pipe 6 nozzle plate 6a nozzle 7 Drive circuit printed board 8 lead wires 9 Drive electrode 10 grooves 11 Protective plate 12 Fluid resistance 13, 14 electrodes 15 Upper partition 16 heater 17 Heater power supply 18 Heat transfer member 19 recording head 20 recording media 23 Platen 24 Irradiation light source

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B41J 3/04 101Z

Claims (11)

[Claims] 1. An actinic ray curable ink used in an ink jet recording method in which an ink curable with actinic rays is emitted onto a printing medium and then irradiated with actinic rays. An actinic ray-curable ink, which comprises: 2. An ink jet recording method in which an actinic ray-curable ink that cures with actinic rays is emitted onto a printing medium and then irradiated with an actinic ray, wherein the actinic ray-curable ink comprises a radical polymerizable initiator and a polymerizable monomer. And an ink jet recording method comprising a surface coating agent. 3. The surface energy of the print medium is 36
The ink jet recording method according to claim 2, wherein the ink jet recording method is about 42 dyn / cm. 4. The surface energy of the print medium is 43
The ink jet recording method according to claim 2, wherein the ink jet recording method is about 60 dyn / cm. 5. The ink jet recording method according to claim 2, wherein the print medium is a non-absorbent recording medium. 6. The ink jet recording method according to claim 2, wherein the heat shrinkage rate of the print medium at 80 ° C. is 5 to 50%. 7. The total ink film thickness after the actinic ray curable ink has landed and has been cured by irradiation with actinic rays is 2 to 20.
It is μm, Any one of claims 2 to 6, characterized in that
Inkjet recording method according to item. 8. A proper amount of the ejected ink liquid is 2 to 15 pl.
The ink jet recording method according to any one of claims 2 to 7, wherein 9. The ink jet recording according to claim 2, wherein the actinic ray curable ink is irradiated with an actinic ray within 0.001 to 1 second after landing. Method. 10. The active light has a peak illuminance in a wavelength region effective for curing of 1 mW / cm ² or more and 500 mW / c.
The ink jet recording method according to any one of claims 2-9, characterized in that less than m ^2. 11. The active light has a peak illuminance of 500 mW / cm ² or more and 2000 m in a wavelength region effective for curing.
It is less than W / cm < ² >, The inkjet recording method of any one of Claims 2-9 characterized by the above-mentioned.