JP2003311945A - Inkjet recorder, recording method, and ink for inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink, an inkjet recorder and an inkjet recording method using it, exhibiting excellent anti-clogging properties of an ink head, blur resistance, stability after printing (e.g. durability of image), and the like, and are capable of printing a high resolution image stably on any recording material while controlling the dot diameter. <P>SOLUTION: The inkjet printer for forming an image by ejecting ink contains at least one kind of photopolymerization compound, and a coloring agent from the opening of nozzles onto a recording body and then irradiating the ink with UV-rays. The ink is a liquid having a viscosity of 2-500 mPas at 30°C, a heater is provided in a head section having the nozzles, and the heater is controlled depending on the total number of times of ejecting ink per unit time. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink suitable for recording on any recording medium including a recording medium that does not absorb ink, an ink jet recording apparatus and an ink jet recording method using the ink.

[0002]

2. Description of the Related Art Conventionally, water-soluble liquid ink compositions have been widely used as ink compositions for ink jet recording. Further, while using a hot-melt type ink composition made of a wax or the like which is solid at room temperature, it is liquefied by heating or the like and is jetted by applying some energy, while being adhered on a recording medium (also referred to as a recording medium). A hot melt type ink jet recording method in which recording dots are formed by cooling and solidifying is also proposed.

Since hot melt type ink is solid at room temperature, it does not contaminate others during handling, and since the evaporation amount of ink during melting can be minimized, nozzle clogging does not occur. Further, since it solidifies immediately after being adhered to the recording medium, there is no "bleeding", and various recording media such as Japanese paper, drawing paper, postcards, and plastic sheets can be used without pretreatment. For example, U.S. Pat. No. 4,
Japanese Patent No. 391,369 and Japanese Patent No. 4,484,948 describe the invention of an ink composition capable of providing good print quality regardless of paper quality.

Further, Japanese Patent Application Laid-Open No. 56-93776 discloses an ultraviolet curable resin type ink composition having good adhesion to a metal surface, and further, an ink for ink jet recording which is cured by exposure to ultraviolet rays. Is disclosed in U.S. Pat. No. 4,228,438. This type of ink uses epoxy-modified acrylic resin and urethane-modified acrylic resin as binders, and
It is an ink containing a pigment having a particle diameter of not more than micron as a coloring component. Further, an ink using a cationically polymerizable epoxy resin as a binder disclosed in JP-A-58-32674, a water-soluble or water-insoluble dye as described in JP-A-5-186725. There have been disclosed those which facilitate printing on plain paper and recycled paper.

As described above, there is a demand for an ink jet recording method capable of high-definition printing of a photographic image quality level on various recording media such as various plastic sheets without using ink jet exclusive paper. However, an inkjet recording method having sufficient performance has not been completed yet.

[0006]

When the above water-based ink is used for printing, it is difficult to print on a recording material having no ink absorbency, and a large-sized ink drying device can be used even when special paper is used. is necessary. Further, due to the problem of bleeding, high-definition printing is difficult and the resolution is limited, so that the application is limited.

The hot-melt type ink using wax can print on a recording material having no ink absorbency, and high-speed printing is possible, but its abrasion resistance is very low, and Reliability is difficult to obtain, and smoothness is poor.

On the other hand, the ink jet recording method using an organic pigment as a coloring agent has many advantages over the ink jet recording method using a dye, particularly in terms of weather resistance, and therefore, OA equipment, general household printers, facsimiles. It is expected to be applied not only to office printers, but also to indoor and outdoor posters, large signs, cars, glass, elevators, wall and building decorations, and even printing on cloth.

In addition, the method of curing the ink with light such as ultraviolet rays enables printing on a recording medium that does not absorb ink. However, in an ink jet recording method using a pigment, in which water and an organic solvent are not substantially contained and the ink is cured by light such as ultraviolet rays, a high dot diameter which is aimed at by the present invention is controlled. There is no precedent for fine print. In high-definition printing, it is important that the diameter of dots formed is controlled to be small. When using ink-jet paper with high absorbency, the dot diameter that can be formed can be adjusted only by the amount of ink droplets, but when using inkjet to print onto a recording medium that does not absorb ink , It is difficult to control the dot diameter only by the ink droplet amount.
It is difficult to control the diameter of dots formed from small droplets.

An object of the present invention is to provide an epoch-making ink jet recording method which solves all the above problems.

That is, the ink head is excellent in clogging, bleeding resistance, stability after printing (image durability, etc.), and stable for all recording materials capable of high-definition printing with a controlled dot diameter. Accordingly, it is an object of the present invention to provide an inkjet recording ink capable of printing a high-definition image, and an inkjet recording apparatus and an inkjet recording method using the same.

[0012]

Means for Solving the Problems As a result of intensive studies by the present inventors, the object of the present invention can be achieved by adopting any of the following constitutions.

[1] In an ink jet recording apparatus for ejecting an ink containing at least one photopolymerizable compound and a colorant onto a recording medium through an opening of a nozzle and then irradiating ultraviolet rays to form an image. The ink is a liquid having a viscosity of 2 to 500 mPa · s at 30 ° C., a heater is installed in the head portion having the nozzle, and the heater is set in accordance with the total number of discharges of the ink per unit time. An inkjet recording device characterized by controlling.

[2] The ink jet recording apparatus according to [1], characterized in that the heater is controlled so that the time for operating the heater is shortened as the total number of ink ejections per unit time increases.

[3] Before the ink is ejected according to the image data, the heater is controlled according to the total number of ink ejections per unit time calculated from the image data [1] ] Or the inkjet recording device of [2].

[4] The ink jet recording apparatus according to any one of [1] to [3], wherein the partition walls between the ink channels of the pressure generating chamber are made of piezoelectric elements.

[5] The ink jet recording apparatus according to any one of [1] to [4], which is composed of an ink having a viscosity at 30 ° C. of 10 to 500 mPa · s.

[6] An ink jet recording apparatus according to any one of [1] to [5], wherein the ejection amount per dot is 2 to 20 pl.

[7] The ink jet recording apparatus according to any one of [1] to [6], wherein the dot diameter formed on the recording medium is 50 to 200 μm.

[8] In the ink used in the ink jet recording apparatus according to any one of [1] to [7],
An ink for an inkjet recording device, which is substantially free of water and an organic solvent.

[0021]

[9] In the ink used in the inkjet recording device according to any one of [1] to [7],
An ink for an inkjet recording apparatus, wherein the colorant is a pigment, the average dispersed particle diameter of the pigment is 200 nm or less, and the addition amount is 0.5 to 30% by mass.

[10] An ink jet recording method comprising forming an image using the ink jet recording apparatus according to any one of [1] to [7].

[11] An ink jet recording method using a recording medium having no ink absorbency in the ink jet recording apparatus according to any one of [1] to [7].

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION [Ink Heating, Head Temperature Adjustment] In the recording method of the present invention, a heating heater is installed in the head portion. From the viewpoint of ejection stability, it is preferable to heat the ink to 40 to 150 ° C. with the heater to reduce the ink viscosity and eject the ink. More preferably, it is 40 ° C to 100 ° C. If the temperature is lower than 40 ° C or higher than 150 ° C, it becomes difficult to select the material. The radiation curable ink generally has a higher viscosity than the water-based ink even at this temperature, and thus the viscosity fluctuation range due to temperature fluctuation is large.

Since the viscosity fluctuation directly affects the droplet size and the droplet ejection speed as they are, and the image quality is deteriorated, it is necessary to keep the ink temperature as constant as possible. The control range of the ink temperature is set temperature ± 5 ° C, preferably set temperature ± 2 ° C, and more preferably set temperature ± 1 ° C. The recording device is equipped with a means for stabilizing the ink temperature, but the part that keeps the temperature constant is the ink tank (intermediate tank if there is an intermediate tank) and the piping system from the nozzle ejection surface, and heaters are installed on all members. May be installed. In order to control the temperature, it is preferable to provide a plurality of temperature sensors at each piping site and control heating according to the environmental temperature. Further, it is preferable that the head unit to be heated is thermally shielded or insulated so as not to be affected by the temperature from the apparatus body and the outside air. In order to shorten the printer startup time required for heating and to reduce the loss of thermal energy, it is preferable to perform heat insulation from other parts and reduce the heat capacity of the entire heating unit.

In the present invention, in addition to controlling the heater installed in the head portion in accordance with the ink temperature, the heater is controlled in accordance with the total number of times ink is ejected per unit time. What is said per unit time here?
It is 10 seconds to 0.1 seconds, preferably 1 second to 0.
1 second. The total number of ejections is the number of ejections per head ejected per unit time. As a control method, it is preferable to shorten the time for operating the heater as the total number of discharges increases. Specifically, the heater that is already operating before discharge is controlled so as to increase the time during which it is not operated, depending on the total number of discharges. Further, it is preferable to control the heater according to the total number of ink ejections per unit time calculated from the image data before the ink is ejected according to the image data to be formed. The term "before discharge" as used herein means to control the heater 10 seconds to 0.1 second before discharge.

[Inkjet Recording Device] FIG. 1 is a cross-sectional view of the configuration of a recording head of an embodiment of the inkjet recording device according to the present invention. In the figure, 1 is a substrate, 2
Is a piezoelectric element, 3 is a flow path plate, 3a is an ink flow path, 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, and 7 is a drive circuit. Printed circuit board (PCB), 8 is a lead wire, 9 is a drive electrode, 11 is a protective plate, 12 is a fluid resistance, 16 is a heater, 1
Reference numeral 7 is a heater power source, 18 is a heat transfer member, and 19 is a recording head.

FIG. 2 is an exploded view of the recording head. 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. The heat transfer member 18 is the heater 16
Heat from the heater 16 can be efficiently transmitted to the flow path plate 3 and the heater 16
The purpose is to carry the heat from the nozzle to the vicinity of the nozzle surface to warm the air in the vicinity of the nozzle surface. Therefore, a material having a high thermal conductivity is used. For example, metals such as aluminum, iron, nickel, copper, stainless steel, or SiC, B
Ceramics such as eO and AlN are preferable materials.

When the piezoelectric element is driven, the piezoelectric element is displaced in the direction perpendicular to the longitudinal direction of the flow path, and the volume of the flow path changes, 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.

3A and 3B are views for explaining how ink is ejected as ink droplets. FIG. 3A is a sectional view of a head portion, and FIG. 3B is a plan view of a nozzle plate. is there. In the figure, 20 is a recording medium, 21 is an ink droplet, 22a ...
22j is a nozzle and 23 is a platen. The ink droplet 21 ejected from the nozzle 22 flies toward the recording medium 20 and adheres thereto.

[Ejection amount] The ejection amount per dot is 20
~ 2 pl is preferred. It is more preferably 10 pl or less, and further preferably 10 pl or less to 4 pl or more. 20p
If it exceeds 1, it is difficult to perform high-definition printing, and if it is less than 2 pl, the density of the formed image becomes low.

[Dot Diameter] The dot diameter formed on the recording medium is preferably 50 to 200 μm. More preferably 5
The thickness is 0 to 150 μm, and more preferably 55 to 120 μm. If it is less than 50 μm, the density of the formed image will be low, and if it exceeds 200 μm, high-definition printing will be difficult. It is difficult to obtain a high-definition image by controlling the dot diameter only by the droplet amount, and it is preferable to adjust the ink viscosity, the ultraviolet ray intensity, and the irradiation timing in addition to the ink droplet amount. The dot diameter can be controlled, enabling high-definition printing.

[Irradiation Ray Source] As the ultraviolet ray source, a mercury lamp, a metal halide lamp, an excimer lamp, an ultraviolet laser, an LED or the like can be used.

The basic irradiation method is disclosed in JP-A-60-132.
It is disclosed in Japanese Patent Publication No. 767. 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 time has elapsed after the ink has landed. Further, curing is completed by another light source that is not driven. WO9954415 discloses, as an irradiation method, a method using an optical fiber and a method of irradiating a recording section with UV light by applying a collimated light source to a mirror surface provided on the side surface of the head unit. In the recording method of the present invention, these irradiation methods can be used.

Specifically, a strip-shaped metal halide lamp tube and an ultraviolet lamp tube are preferable. The radiation source is substantially fixed to the recording device, and the moving part is eliminated, so that an inexpensive structure can be obtained.

It is preferable that the irradiation is performed for each printing of each color, that is, it is preferable that two kinds of radiation sources are prepared and the curing is completed by the second radiation source in any exposure method. This contributes to obtaining the wettability of the second color landing ink and the adhesiveness between the inks, and to assemble the radiation source at low cost.

It is preferable that the first radiation source and the second light source have different exposure wavelengths or exposure illuminances. The first irradiation energy is smaller than the second irradiation energy, that is, the first irradiation energy is 1 to 20 of the total irradiation energy.
%, Preferably 1 to 10%, more preferably 1 to 5%. By performing irradiation with different illuminance, the molecular weight distribution after curing becomes preferable. That is, when irradiation with high illuminance is performed at one time, the polymerization rate is increased, but the molecular weight of the polymerized polymer is small, and strength cannot be obtained. By changing the illuminance, a remarkable effect can be obtained in a composition having an extremely low viscosity such as an inkjet ink.

Further, the first irradiation is performed with the second longer wavelength so that the surface layer of the ink is hardened in the first irradiation to suppress the ink bleeding, and the irradiation line is used in the second irradiation. It is possible to cure the ink in the vicinity of the recording medium, which is hard to reach, to improve the adhesion. In order to accelerate the curing inside the ink, the second irradiation ray wavelength is preferably long wavelength.

[Irradiation Timing] In the recording method of the present invention, the ink described below is used, the ink is heated to a constant temperature, and the time from impact to irradiation is 0.01.
˜0.5 seconds, preferably 0.01 to 0.3 seconds, and more preferably 0.01 to 0.15 seconds. By controlling the time from landing to irradiation to an extremely short time in this way, it becomes possible to prevent the landing ink from bleeding before curing. In addition, since it is possible to expose the porous recording medium before the ink penetrates to a deep portion where the light source does not reach, residual unreacted monomer can be suppressed and odor can be reduced.

By adopting such a recording method, the dot diameter of the landed ink can be kept constant and the image quality can be improved even on various recording media having different wettability on the surface. Note that in order to obtain a color image, it is preferable to superimpose the colors in order of low lightness. When inks with low brightness are piled up, it is difficult for the irradiation line to reach the lower ink, which hinders the curing sensitivity, increases the amount of residual monomer, and causes odor.
Adhesion is likely to deteriorate. In addition, it is possible to irradiate all colors and expose them collectively, but it is preferable to expose each color one by one from the viewpoint of accelerating curing.

[Ink Absorptive Recording Medium] The recording material having no ink absorptivity or the recording material having a low ink absorptivity (or the ink non-absorptive recording material) in the present invention means
A recording medium made of a material having no ink absorption or a material having low ink absorption (or an ink non-absorption material),
Alternatively, it is a recording medium having a surface layer (printing layer) made of a material having no ink absorbability or a material having low ink absorbability (or an ink non-absorbent material), and the material having no ink absorbability or the ink absorbability. Low materials (or ink non-absorbent materials) are, for example, various plastics and metals.

[Water and Organic Solvent] The ink of the present invention preferably contains substantially no water or organic solvent. The term "substantially free from" means that the content of water and the organic solvent is less than 1% by mass. Moreover, the example of the organic solvent said here is shown below.

Examples of the organic solvent include high boiling point and low volatility polyhydric alcohols such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, polyethylene glycol and polypropylene glycol. To be Further, mono-ether compounds, di-ether compounds and ester compounds thereof such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether can be mentioned. Further, cellosolves such as methyl cellosolve and ethyl cellosolve, carbitols such as methyl carbitol and ethyl carbitol, morpholines such as morpholine and N-ethylmorpholine, and pyrrolidones such as N-methyl-2-pyrrolidone. Be done. Furthermore, highly volatile monohydric alcohols such as ethanol, propanol, isopropanol and butanol are also included.

Further, ethyl acetate, butyl acetate, methyl benzoate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, N-methyl-2-pyrrolidone,
Examples thereof include N, N dimethylformamide, ethylene glycol ethers, ethylene glycol acetates, propylene glycol ethers and propylene glycol acetates.

[Viscosity of Ink] The ink of the present invention is a liquid having a viscosity at 30 ° C. of 2 to 500 mPa · s. Preferably, it is 10 to 500 mPa · s.
If it is less than 2 mPa · s, bleeding is deteriorated, and 500 mPa
・ If it exceeds s, the smoothness of the image quality is lost. Further, the ink is preferably a liquid of 3 to 30 mPa · s at 60 ° C., and more preferably 3 to 20 mPa · s. At 3 mPa · s or less, problems occur in high-speed injection,
Further, if it is 500 mPa · s or more, the injection property deteriorates.

[Photopolymerizable Compound, Photopolymerization Initiator] The photopolymerizable compound is a radical polymerizable compound, for example, JP-A-7-
159983, Japanese Examined Patent Publication No. 7-31399, JP-A-8-
A photo-curable material using a photo-polymerizable composition described in JP-A No. 224982 and JP-A No. 10-863 and a photo-curable resin of a cation polymerization type are known, and more than visible light recently. The photo-curable resin of the photo-cationic polymerization system sensitized to the long wavelength region of JP-A-6-43633 is also disclosed.
It is disclosed in Japanese Patent Laid-Open No. 8-324137.

The radical-polymerizable compound is a compound having a radical-polymerizable ethylenically unsaturated bond, and may be any compound as long as it has at least one radical-polymerizable ethylenically unsaturated bond in the molecule. Often,
Those having chemical forms such as monomers, oligomers and polymers are included. The radical-polymerizable compound may be used alone, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve target properties.

Examples of the radically polymerizable compound having an ethylenically unsaturated bond include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid, and salts and esters thereof.
Radical polymerizable compounds such as urethane, amide and anhydride, acrylonitrile, styrene, and various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides and unsaturated urethanes can be mentioned. 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, dipentaerythritol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, acrylic acid derivatives such as N-methylol acrylamide, diacetone acrylamide, epoxy acrylate, methyl methacrylate, n- Butylme Acrylate, 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, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxy) Methacryl derivatives such as polyethoxyphenyl) propane, other, allyl glycidyl ether, diallyl phthalate, derivatives of allyl compounds such as triallyl trimellitate, more specifically, Shinzo Yamashita, "Crosslinking agent handbook", (1981 Taiseisha); Kiyomi Kato, "UV / EB curing handbook (raw materials)" (1985, Kobunshi Kogyokai); Radtech Research Group, "UV / EB" Application of technology and the market ", 79
Page, (1989, CMC); Eiichiro Takiyama,
Commercially available products described in "Polyester Resin Handbook" (1988, Nikkan Kogyo Shimbun) and the like, or radically polymerizable or crosslinkable monomers, oligomers and polymers known in the art can be used. The amount of the radically polymerizable compound added is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

As a radical polymerization initiator, Japanese Examined Patent Publication No. S59
-1281, Japanese Patent Publication No. 61-9621, and JP-A-6-6
Triazine derivatives described in each publication such as 0-60104,
JP-A-59-1504 and JP-A-61-243807
Organic peroxides described in each publication such as Japanese Patent Publication No. 43-23
684, Japanese Patent Publication No. 44-6413, Japanese Patent Publication No. 44-64
No. 13 and Japanese Patent Publication No. 47-1604, and diazonium compounds described in US Pat. No. 3,567,453, US Pat. Nos. 2,848,328, 2,852,379, and No. 2,940,853, organic azide compounds described in each specification, JP-B-36-2206
No. 2, JP-B-37-13109, JP-B-38-180
No. 15, Japanese Patent Publication No. 45-9610 and other ortho-quinone diazides, Japanese Patent Publication No. 55-39162,
JP-A-59-14023 and the like, and "Macromolecules, No. 10"
Vol. 1, p. 1307 (1977), various onium compounds, azo compounds described in JP-A-59-142205, JP-A-1-54440, EP 109,851, and EP 126. , 712
No. etc., each statement, "Journal of Imaging
Science "(J.Imag.Sci.)", No. 30
Vol., Page 174 (1986), metal allene complexes, Japanese Patent Application No. 4-56831 and Japanese Patent Application No. 4-89.
(Oxo) sulfonium organoboron complex described in Japanese Patent No. 535, a titanocene described in Japanese Patent Application Laid-Open No. 61-151197, "Coordination Chemistry Review (Coordination Chemistry Review)".
y Review) ", Vol. 84, 85, p. 277 (1988) and transition metal complexes containing a transition metal such as ruthenium described in JP-A-2-182701.
2,4,5-triarylimidazole dimers and carbon tetrabromide described in JP-A-3-209477 and JP-A-5-
Examples thereof include organic halogen compounds described in JP-A 9-107344. 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 a radically polymerizable ethylenic unsaturated bond.

As the cationic polymerization type photocurable resin, an epoxy type ultraviolet curable prepolymer of a type (mainly an epoxy type) in which polymerization is caused by cationic polymerization, and a monomer has two or more epoxy groups in one molecule. The prepolymer contained can be mentioned. Examples of such prepolymers include alicyclic polyepoxides, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyhydric alcohols, polyglycidyl ethers of polyoxyalkylene glycols, and polyglycidyl aromatic polyols. Examples thereof include ethers, hydrogenated compounds of polyglycidyl ethers of aromatic polyols, urethane polyepoxy compounds and epoxidized polybutadienes. These prepolymers can be used alone, or in addition,
It is also possible to use a mixture of two or more thereof.

Examples of the cationically polymerizable compound contained in the cationically polymerizable composition include, for example, the following (1) styrene derivative, (2) vinylnaphthalene derivative, and (3).
Examples thereof include vinyl ethers and (4) N-vinyl compounds. (1) Styrene derivative For example, 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-
Vinyl naphthalene and the like. (3) Vinyl ethers For example, isobutyl vinyl ether, ethyl vinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-methoxyphenyl vinyl ether,
Examples include α-methylphenyl vinyl ether, β-methyl isobutyl 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 content of the above cationically polymerizable compound in the cationically polymerizable composition is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

Aromatic onium salts can be mentioned as the initiator of the cationically polymerizable photocurable resin. As the aromatic onium salt, a salt of a Group Va element of the periodic table, for example, a phosphonium salt (for example, triphenylphenacylphosphonium hexafluorophosphate), a salt of a Group VIa element, for example, a sulfonium salt (for example, triphenylsulfonium tetrafluoroborate) , Triphenylsulfonium hexafluorophosphate, tris (4-thiomethoxyphenyl) hexafluorophosphate, sulfonium and triphenylsulfonium hexisafluoroantimonate), and salts of Group VIIa elements, such as iodonium salts (eg, diphenyliodonium chloride). Etc.) can be mentioned.

The use of such an aromatic onium salt as a cationic polymerization initiator in the polymerization of epoxy compounds is described in US Pat. Nos. 4,058,401 and 4,0.
69,055, 4,101,513 and 4,161,478.

Preferred cationic polymerization initiators include
Examples thereof include sulfonium salts of Group VIa elements. Among them, from the viewpoint of ultraviolet curability and storage stability of the ultraviolet curable composition, triarylsulfonium hexafluoroantimonate is preferable. Also, Photo Polymer Handbook (Photo Polymer Conversation Edition, Industrial Research Committee issue 1
989), pages 39 to 56, known photopolymerization initiators, and compounds described in JP-A No. 64-13142 and JP-A No. 2-4804 can be optionally used. .

[Coloring Agent] As the coloring agent in the ink composition of the present invention, conventionally known dyes and pigments can be used. As the coloring agent in the present invention, a pigment is more preferable.

Examples of the water-soluble dye include C.I. I. Direct Black-2, -4, -9, -11, -17,-
19, -22, -32, -80, -151, -154,
-168, -171, -194; C.I. I. Direct Blue-1, -2, -6, -8, -22, -34, -7
0, -71, -76, -78, -86, -112, -1
42, -165, -199, -200, -201, -2
02, -203, -207, -218, -236, -2
87; C.I. I. Direct Red-1, -2, -4,-
8, -9, -11, -13, -15, -20, -28,
-31, -33, -37, -39, -51, -59,-
62, -63, -73, -75, -80, -81, -8
3, -87, -90, -94, -95, -99, -10
1, -110, -189; C.I. I. Direct Yellow-1, -2, -4, -8, -11, -12, -26,-
27, -28, -33, -34, -41, -44, -4
8, -58, -86, -87, -88, -135, -1
42, -144; C.I. I. Food black-1, -2;
C. I. Acid Black-1, -2, -7, -16,
-24, -26, -28, -31, -48, -52,-
63, -107, -112, -118, -119, -1
21, -156, -172, -194, -208;
I. Acid Blue-1, -7, -9, -15, -2
2, -23, -27, -29, -40, -43, -5
5, -59, -62, -78, -80, -81, -8
3, -90, -102, -104, -111, -18
5, -249, -254; C.I. I. Acid Red-
1, -4, -8, -13, -14, -15, -18,-
21, -26, -35, -37, -110, -144,
-180, -249, -257; C.I. I. Acid Yellow-1, -3, -4, -7, -11, -12, -1
3, -14, -18, -19, -23, -25, -3
4, -38, -41, -42, -44, -53, -5
5, -61, -71, -76, -78, -79, -12
2 etc.

The oil-soluble dyes include azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoimine dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, and naphthalene dyes. Phthalimide dye,
Examples include perinone dyes and phthalocyanine dyes,
It is not limited to these.

The water-insoluble dyes and pigments are not particularly limited, but include organic pigments, inorganic pigments, colored polymer particles, water-insoluble dyes, disperse dyes and oil-soluble dyes. Examples of black pigments include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. For example, Raven 7000, Raven 5750, Rav.
en5250, Raven5000 ULTRA II,
Raven3500, Raven2000, Raven
1500, Raven 1250, Raven 1200,
Raven1190 ULTRA II, Raven11
70, Raven 1255, Raven 1080, Ra
ven1060 (above, Colombian carbon company make), Regal400R, Regal330R, Re
gal660R, Mogul L, Black Pea
rls L, Monarch700, Monarch8
00, Monarch, 880, Monarch90
0, Monarch1000, Monarch110
0, Monarch1300, Monarch1400
(Above made by Cabot), Color Black F
W1, Color BlackFW2, Color B
rack FW2V, Color Black 18,
Color Black FW200, Color B
rack S150, Color Black S16
0, Color Black S170, Pritex
35, Printex U, Printex Vrintex
140U, Printex140V, Special
Black 6, Special Black 5, S
special Black 4A, Special B
rack4 (above, manufactured by Degussa), No. 25, N
o. 33, No. 40, No. 47, No. 52, N
o. 900, No. 2300, MCF-88, MA60
0, MA7, MA8, MA100 (above, manufactured by Mitsubishi Chemical Co., Ltd.) and the like can be used.

Further, magnetic fine particles such as magnetite and ferrite, titanium black and the like can be used as the black pigment.

Cyan color pigments include C.I. I. Pigment Blue-1, C.I. I. Pigment Blue-2,
C. I. Pigment Blue-3, C.I. I. Pigment Blue-15, C.I. I. Pigment Blue-15:
1, C.I. I. Pigment Blue-15: 3, C.I. I.
Pigment Blue-15: 34, C.I. I. Pigment Blue-16, C.I. I. Pigment Blue-22,
C. I. Pigment Blue-60 and the like.

Examples of magenta pigments include C.I. I. Pigment Red-5, C.I. I. Pigment Red-7,
C. I. Pigment Red-12, C.I. I. Pigment Red-48, C.I. I. Pigment Red-4
8: 1, C.I. I. Pigment Red-57, C.I. I.
Pigment Red-112, C.I. I. Pigment Red-122, C.I. I. Pigment Red-123,
C. I. Pigment Red-146, C.I. I. Pigment Red-168, C.I. I. Pigment Red-
184, C.I. I. Pigment Red-202 and the like.

As the yellow pigment, C.I. I. Pigment
Yellow-1, C.I. I. Pigment Yellow-2,
C. I. Pigment Yellow-3, C.I. I. Pigment yellow-12, C.I. I. Pigment Yellow-
13, C.I. I. Pigment Yellow-14, C.I. I.
Pigment yellow-16, C.I. I. Pigment Yellow-17, C.I. I. Pigment Yellow-73,
C. I. Pigment Yellow-74, C.I. I. Pigment Yellow-75, C.I. I. Pigment Yellow-83, C.I. I. Pigment Yellow-93, C.I.
I. Pigment Yellow-95, C.I. I. Pigment Yellow-97, C.I. I. Pigment Yellow-9
8, C.I. I. Pigment Yellow-114, C.I. I.
Pigment Yellow-128, C.I. I. Pigment
Yellow-129, C.I. I. Pigment Yellow-1
51, C.I. I. Pigment Yellow-154 and the like.

In addition to the above-mentioned three primary color pigments of black and cyan, magenta and yellow, specific color pigments such as red, green, blue, brown and white, metallic luster pigments such as gold and silver, colorless extender pigments,
It is also possible to use a plastic pigment or the like. In addition to the above, a newly synthesized pigment may be used. Further, these pigments may be surface-treated. Examples of the surface treatment method include treatment with a coupling agent such as alcohol, acid, base and silane compound, polymer grafting treatment, and plasma treatment. The coloring material used in the present invention preferably has a small content of organic and inorganic impurities. Generally, since commercially available coloring materials have a large content of impurities, it is desirable to use a purified product thereof. The color material used in the solid ink composition of the present invention is 0.1 to the ink mass.
It is used in the range of 30% by mass, preferably 1 to 15% by mass.

[Pigment Dispersion, Dispersion Particle Size] In the present invention,
Preference is given to using dispersed pigments.

Examples of the dispersant used for dispersing the pigment include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates and alkyl phosphates. , Polyoxyalkylene alkyl ether phosphate,
Activator such as polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, or styrene, styrene derivative, vinylnaphthalene derivative, acrylic acid, acrylic acid Examples thereof include block copolymers, random copolymers and salts thereof composed of two or more monomers selected from derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives. be able to.

For dispersing the pigment, various types such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill and a paint shaker can be used. It is also preferable to remove coarse particles from the pigment dispersion using a centrifugal separator or using a filter.

The average particle size of the pigment dispersion used in the ink of the present invention is preferably 200 nm or less, more preferably 100 nm or less.

The addition amount of the pigment dispersion used in the ink of the present invention is generally preferably in the range of 0.5 to 30% by mass, more preferably 1 to 20%.

In addition to the above, the ink of the present invention contains a preservative,
A mildew-proofing agent, a viscosity modifier, etc. may be contained as necessary.

[Other Additives] As additives to the ink of the present invention, other additives such as a reaction diluent, a filler, a flow aid, a thixotropic agent, a wetting agent, a defoaming agent and a plasticizer may be used. Can be included. In addition, stabilizers such as light stabilizers, ultraviolet absorbers, antioxidants, polymerization inhibitors, and corrosion inhibitors, or Si compounds, waxes, etc. may be added.

[PH] The pH of the ink in the present invention is
It is preferably 4 to 10. More preferably, 5
~ 9. Although the reason for the effect of the present invention is not clear, it is considered that the compatibility between the pigment and the photopolymerizable compound contributes to the dispersion stability of the pigment.

[Surface Tension] In the ink of the present invention,
The surface tension of the ink needs to be in the range of 20 to 60 mN / m, preferably 25 to 50 mN / m, in consideration of the wettability with respect to the recording material and the head nozzle member.
It is set in the range of m. Ink surface tension is 25mN /
When it is lower than m, the ink easily overflows from the nozzle, and when it is higher than 60 mN / m, the drying time becomes long.

To adjust the surface tension, a surfactant may be contained, if necessary. As the surfactant preferably used in the ink of the present invention, for example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyls. Examples thereof include nonionic surfactants such as ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. Of these, anionic surfactants and nonionic surfactants are particularly preferable.

[0075]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the forms in these examples.

[Ink Composition] The following ink composition was added to 60
After heating the solid ink to 150 ° C. and mixing and stirring, the obtained liquid was filtered with a filter under heating and cooled to obtain an ink composition. However, the ink 2 was prepared by mixing without heating.

(Ink 1) (for comparison; solid ink) Colorant: C.I. I. Pigment Blue 15: 3 = 5 parts by mass (average dispersed particle size; 100 nm) Paraffin wax (155, manufactured by Nippon Seiro Co., Ltd.) 45 parts by mass Behenic acid (manufactured by Wako Pure Chemical Industries, Ltd.) 30 parts by mass Oleic acid amide (Kao Corporation) Manufactured by Fatty Acid Amide ON) 20 parts by mass (Ink 2) Cyan pigment dispersion C.I. I. Pigment Blue 15: 3 20 parts by mass Polymeric dispersant (Solsperse series manufactured by Zeneca) 5 parts by mass Stearyl acrylate 75 parts by mass In addition, the dispersion condition is that the average particle size of each pigment particle is 0.2 to 0.
Using a known dispersion device so that the range is 3 μm,
It was prepared by appropriately adjusting the dispersion conditions and then filtering with heating.

Cyan pigment dispersion 5 parts by mass Photopolymerizable compound: lauryl acrylate (monofunctional) 10 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (trifunctional) 10 parts by mass Caprolactam modified dipentaerythritol hexaacrylate (hexafunctional) 10 to 40 parts by mass Tetraethylene glycol diacrylate (bifunctional) 5 to 30 parts by mass (Addition amount is adjusted so that the viscosity becomes the value in the table) Polymerization initiator: Irgacure 184 (manufactured by Nippon Ciba Geigy) 2.5 Ink 2 was prepared by adding 2.5 parts by mass of Irgacure 907 (manufactured by Ciba-Geigy) and filtering it with a filter having an absolute filtration accuracy of 2 μm.

(Ink 3) Cyan pigment dispersion 5 parts by mass Photopolymerizable compound: lauryl acrylate (monofunctional) 10 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (trifunctional) 10 parts by mass AT-600 (Kyoeisha Chemical Co., Ltd. 10-40 parts by mass Tetraethylene glycol diacrylate (bifunctional) 5-30 parts by mass (addition amount is adjusted so that the viscosity becomes a value in the table) Polymerization initiator: Irgacure 184 (manufactured by Nippon Ciba Geigy) 2 0.5 parts by mass Irgacure 907 (manufactured by Japan Ciba Geigy) 2.5 parts by mass (Ink 4) Cyan pigment dispersion (average dispersed particle size: 100 nm) 5 parts by mass Photopolymerizable compound: 1,6-hexanediol diacrylate 15 Parts by weight 2-phenoxyethyl acrylate 20 parts by weight polypropylene glycol di Acrylate 10 to 20 parts by mass Octyl acrylate 10 to 29 parts by mass (Addition amount is adjusted so that the viscosity becomes a value in the table) Polymerization initiator: Irgacure 184 (manufactured by Nippon Ciba Geigy) 5 parts by mass 2-phenoxyethanol 1 part by mass [Inkjet image recording] Next, recording was performed on a recording medium by using an inkjet recording apparatus basically having the configuration of FIGS. The ink supply system was composed of a main tank, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo type inkjet head. The ink supply tank and the inkjet head were thermally insulated and heated. Temperature sensors are installed on the ink supply tank and inkjet head respectively, and the set temperature is ± 2 ° C.
The temperature was controlled so that Further, independently of this temperature control, the power source for driving the heater was controlled according to the number of ejections of the head. For the control, the time to stop the driving heater was set in the table according to the number of discharges per unit time in the table. At that time, the timing of stopping the heater was set as shown in the table with reference to the time point when the ink was ejected from the head.

The piezo type ink jet head is
Multi-size dots of 30 pl at 720 x 720 dpi
It was driven so as to be able to eject at a resolution of (dpi represents the number of dots per inch (2.54 cm)). After landing, the UV light was changed to an exposure surface illuminance of 1 to 100 mW / cm ^2, and the dot diameter was adjusted by increasing the illuminance to reduce the dot diameter and decreasing the illuminance to increase the dot diameter.

The exposure system, the main scanning speed and the emission frequency were adjusted so that the irradiation was started after the ink was landed on the recording medium.

Using the color inks prepared above, an ambient temperature of 2
It was irradiated with UV light at 5 ° C. The total exposure energy per color was uniformly 300 mJ / cm ² as the energy for completely curing so that the tackiness disappeared by touch. A PET film was used as the recording medium.

Viscosity The viscosity at 30 ° C. was measured by a rotary viscometer (E manufactured by Tokimec Co., Ltd.
DL model).

Head set temperature The inks of the present invention were printed at the ink temperatures set in the table, the comparative sample solid ink at 150 ° C and the comparative sample UV curable ink at 25 ° C.

[Characteristic Evaluation Method] 1. Continuous ejection property (bleeding) 100 sheets were continuously printed with a piezo type inkjet printer, and the printability was visually observed and judged.

⊚: No nozzle deficiency and good printability ◯: No nozzle deficiency but slight print disturbance Δ: Slight nozzle deficiency and print disturbance ×: There are many nozzle failures and printing is disturbed 2. Re-ejectability (ink clogging) After printing with a piezo type inkjet printer,
After left at the printing temperature for 6 hours, printing was performed again, and clogging and the like were confirmed by comparing printed matters.

⊚: No clogging and good printability ○: Slight omission can be observed Δ: Clogging, but printing is possible with a simple recovery operation ×: Printing is not possible Image durability For solid parts printed with a piezo type inkjet printer, scratch strength tester HEIDON-18
(Manufactured by HEIDON) and a 0.8 mm R sapphire needle was used as a measuring needle. Measurement is a constant load 10
The scratch test of cm was carried out three times, and the limit load at which there was no scratched portion up to the support was taken as the scratch strength of the present invention, and judged according to the following criteria.

◯: 200 g or more, Δ: less than 200 g, 100 g or more, x: less than 100 g 4. The solid portion (black) was printed with a smoothness piezo type inkjet printer, and after irradiating with ultraviolet rays, the ink film thickness was measured.

⊚: Thin and good ○: Thick but no problem for high-definition printing Δ: Thickness Slightly problematic for high-definition printing ×: Thick, unusable level Printing quality 8-point characters were printed, and the roughness of the characters and the shape of 1 dot for each color were magnified and evaluated with a magnifying glass.

∘: There is no roughness and the dot shape is perfect circle. ×: Roughness is visible and the dot shape is bad.Similar results are obtained for surface-treated transparent biaxially oriented polypropylene film with printability, soft vinyl chloride sheet, aluminum vapor-deposited paper, polyethylene film, polystyrene film. was gotten.

[0091]

[Table 1]

By adjusting the applied voltage, the droplet ejection speed was 5 to 10 m / s and the droplet amount was as shown in the table. 3 *: 10% by mass of methyl ethyl ketone was added to Ink 3.

[0093]

[Table 2]

It is understood that Examples 1 to 17 in the present invention have good characteristics, while Comparative Examples 1 to 3 have a problem in at least one of the characteristics.

[0095]

According to the present invention, the ink head is excellent in clogging, bleeding resistance, stability after printing (image durability, etc.), and enables high-definition printing with a controlled dot diameter. It is possible to provide an inkjet recording ink capable of stably printing a high-definition image on a recording material, and an inkjet recording device and an inkjet recording method using the same.

[Brief description of drawings]

FIG. 1 is a configuration cross-sectional view for explaining an example of an aspect of an inkjet recording apparatus according to the present invention.

FIG. 2 is an exploded configuration diagram of a recording head.

FIG. 3 is a diagram for explaining how ink is ejected as ink droplets.

[Explanation of symbols] 1 substrate 2 Piezoelectric element 3 flow path plates 3a ink flow path 4 Common liquid chamber components 4a Common liquid chamber 5 Ink supply pipe 6 nozzle plate 6a nozzle 7 Drive circuit printed board (PCB) 8 lead wires 9 Drive electrode 11 Protective plate 12 Fluid resistance 16 heater 17 Heater power supply 18 Heat transfer member 19 recording head

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 11/00 F term (reference) 2C056 EA04 EB49 EC07 EC29 FA04 FB04 FD20 HA15 HA44 2C057 AG45 AK01 AL31 AM24 BA05 BA14 2H086 BA02 BA05 BA19 BA55 BA59 BA60 BA61 BA62 4J039 AD03 AD07 AD09 AD10 AD21 AE05 BC51 BD02 BE01 BE02 BE27 EA06 EA41 EA44 EA46 EA47 GA24

Claims (11)

[Claims] 1. An ink jet recording apparatus for forming an image by irradiating an ultraviolet ray onto a recording medium after ejecting an ink containing at least one photopolymerizable compound and a colorant onto the recording medium. The ink is a liquid having a viscosity of 2 to 500 mPa · s at 30 ° C., a heater is installed in the head portion having the nozzle, and the heater is controlled according to the total number of times of discharging the ink per unit time. An ink jet recording apparatus characterized by: 2. The control is performed so that the time for operating the heater is shortened as the total number of ink ejections per unit time increases.
The inkjet recording device described. 3. The heater is controlled according to the total number of ink ejections per unit time calculated from the image data before the ink is ejected according to the image data. Or the ink jet recording apparatus according to 2. 4. The ink jet recording apparatus according to claim 1, wherein the partition wall between the ink channels of the pressure generating chamber is formed of a piezoelectric element. 5. The ink jet recording apparatus according to claim 1, wherein the viscosity at 30 ° C. is 1.
An inkjet recording apparatus comprising an ink of 0 to 500 mPa · s. 6. The inkjet recording apparatus according to claim 1, wherein the ejection amount per dot is 2 to 20 pl. 7. The ink jet recording apparatus according to claim 1, wherein a dot diameter formed on a recording medium is 50 to 200 μm. 8. The ink for use in an inkjet recording apparatus according to claim 1, which is substantially free of water and an organic solvent. 9. The ink used in the ink jet recording apparatus according to claim 1, wherein the coloring agent is a pigment, the average dispersed particle diameter of the pigment is 200 nm or less, and the addition amount is 0.5 to An ink for an ink jet recording apparatus, which is 30% by mass. 10. An ink jet recording method comprising forming an image using the ink jet recording apparatus according to claim 1. 11. An ink jet recording method, wherein a recording medium having no ink absorbability is used in the ink jet recording apparatus according to any one of claims 1 to 7.