JP2010280751A - Active energy ray-polymerizable material, curable liquid composition containing the material, ink, inkjet recording method, ink cartridge, recording unit, and inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray-curable aqueous inkjet ink which is rapidly polymerized by active energy rays of low energy capable of being deployed on high-speed aqueous inkjet printing and of which the cured product formed has a high degree of crosslinking and does not substantially cause hydrolysis when used in an aqueous system. <P>SOLUTION: The active energy ray-curable aqueous inkjet composition contains a hydrophilic polymerizable material 1 having a maleimide group in combination with a hydrophilic polymerizable material 2 having an ethylene unsaturated bond. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel active energy ray polymerizable substance, a curable liquid composition containing the substance, an ink, an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus.

  Conventionally, a technique of using a water-based paint or ink in a method of forming an image by forming a cured resin film by curing a resin composition in ink by light irradiation including an active energy ray is known. As the material composition of the water-based paint and ink used at this time, the following techniques are used. For example, a non-aqueous active energy ray curable resin composition is used which is prepared in an emulsion state in an aqueous solvent, and there is a technology for making an ultraviolet curable resin itself or a catalyst itself aqueous. .

  On the other hand, the technology for applying the active energy ray curable resin composition to the ink jet recording method is also known, and in recent years, it has been applied to the production of electronic circuit boards and display panels in addition to graphic arts, signs, displays, label printing, and package printing. Has been.

  Also in the case where an active energy ray curable ink is used in such an ink jet printing method, non-aqueous and aqueous resin compositions are known. Two types of ink are known as typical non-aqueous inks, and one of them is a so-called oil-based ink in which a pigment is dispersed in an organic solvent such as toluene or methyl ethyl ketone. ing. As another type, a so-called 100% curable ink (non-solvent ink) made of a monomer, an oligomer, and a pigment dispersion without using a solvent is known. However, when the oil-based ink is used, since the organic solvent is volatilized in the atmosphere, sufficient consideration for the environment is necessary. For the 100% curable ink, it is difficult to obtain glossiness of the image due to the unevenness of the printed part and the non-printed part on the recording medium, and it is difficult to develop the application for which high image quality is required. Is the current situation.

  However, the active energy ray curing technique is expected as a curing technique with less energy saving, environmental pollution, and environmental load. Furthermore, the use of active energy ray curing technology is not limited to image printing in inkjet printing, but pretreatment for imparting printability to the printing substrate, and materials for protecting and constructing the printed substrate. It is also useful in post-treatment after coating. In addition, by making the ink water-based, the unevenness of the image, which is a problem of the 100% curable ink, can be alleviated, which is advantageous from the viewpoint of high image quality. Under these circumstances, development of hydrophilic resins, polyfunctional monomers, monofunctional monomers, and photopolymerization initiators (hereinafter also simply referred to as catalysts) that can be applied to water-based active energy ray-curable inks for inkjet recording is required. -ing

  In order to apply an aqueous material to an ink jet recording system, a material having a low viscosity and good flow characteristics that can correspond to a high density nozzle is required. For example, when the amount of polymerizable substance added can be increased, the drying time is shortened, and the ink is applied and cured on the recording medium, the resulting ink film has excellent physical properties and good solubility with the colorant. Photopolymerization initiators, polyfunctional and monofunctional monomers, etc. that are functional materials are required. Among these, regarding the monomer, development of a material having high performance as a polyfunctional monomer is required in consideration of the polymerization rate, film physical properties after polymerization, and the like.

  As a first example of a hydrophilic active energy ray-curable monomer, an acidic group and a (meth) acryloyl group or a vinyl group are both present in the molecule and are hydrophilic polymerizable compounds. Is known. For example, an ester of succinic anhydride and 2-hydroxyethyl (meth) acrylate, an ester of orthophthalic anhydride and 2-hydroxyethyl (meth) acrylate, vinyl naphthalenesulfonic acid, and the like can be given.

  As a second example, a polymerizable compound imparted hydrophilicity by a polyethylene oxide chain is known as an industrially produced compound that is soluble in water and has two or more polymerizable functional groups in one molecule. It has been. Examples of such include (meth) acrylic acid esters of polyhydric alcohols such as diethylene glycol di (meth) acrylate and tetraethylene glycol di (meth) acrylate.

  Patent Document 1 discloses a polyfunctional hydrophilic polymerizable substance. The polymerizable substance disclosed herein uses a technique for obtaining hydrophilicity by increasing the number of hydroxyl groups in the molecule in order to impart hydrophilicity.

  In Patent Documents 2 and 3, (meth) acrylic acid ester of hydrophilic polyepoxide derived from polyalcohol is used. These compounds are excellent in polymerizability by active energy rays and physical properties of the cured product, and the viscosity of the aqueous solution satisfies the level required for the ink for ink jet recording.

JP-A-8-165441 JP 2000-117960 A JP 2002-187918 A

  However, in the first example, since the number of polymerizable functional groups is one in one molecule, the polymerization rate is slow and the degree of crosslinking of the cured product is extremely low. It is difficult to become the main material of the material.

  In the second example, according to the study by the present inventors, these groups of compounds have the following problems. That is, if the length of the ethylene oxide chain is short, the hydrophilicity becomes low. On the other hand, when the length of the ethylene oxide chain is long, hydrophilicity can be obtained, but the solid physical properties of the cured product when polymerized or cured are often insufficient in performance required for paints and inks such as hardness and adhesiveness. .

  Further, in Patent Document 1, according to the study by the present inventors, they are surely excellent in polymerization by active energy rays and excellent in physical properties of the cured product, but the viscosity of the aqueous solution is an ink for ink jet recording. There is a problem that it is slightly higher than the required level.

  In Patent Documents 2 and 3, as an ink coloring material containing a hydrophilic polymerizable compound having a (meth) acrylic acid ester group, an aqueous dye or an anionic functional group that dissolves in water with an anionic functional group. When an aqueous pigment dispersion in which a pigment is dispersed in water is used, the following problems occur. As acrylic acid is generated by hydrolysis of the (meth) acrylic acid ester group, the pH of the ink is lowered to the acidic region. This may cause precipitation of an aqueous dye that is stably dissolved in the alkaline pH to neutral range of the ink, and aggregation of the stably dispersed aqueous pigment dispersion. In terms of the storage stability of the ink over time, There's a problem.

  In addition, in the ink jet recording method in which thermal energy is applied to the ink, the hydrophilic polymerizable substance in the ink undergoes thermal polymerization due to thermal energy, and a water-insoluble polymer is generated in the nozzle, which causes a problem in ink ejection. Sometimes occurred.

  The present inventors have found that, in a water-based ink containing a coloring material using an active energy ray polymerizable substance, a practical curing performance can be obtained with a practical ultraviolet irradiation intensity, and discharge stability and stability over time are excellent. I found it. However, these inks also require the ability to cure even with low energy irradiation in order to cope with inkjet high-speed printing.

  The first object of the present invention is to provide an active energy ray-curable aqueous composition that is rapidly polymerized by low energy active energy rays and has a high degree of crosslinking of the cured product and excellent adhesion to a substrate. There is to do.

  The second object of the present invention is an active energy ray-curable aqueous composition that is rapidly polymerized by low energy active energy rays and has a high degree of cross-linking of the formed cured product and excellent adhesion to a recording medium. Another object of the present invention is to provide an active energy ray-curable water-based ink whose viscosity satisfies the low viscosity level required for ink jet recording and is excellent in storage stability over time.

  The third object of the present invention is to rapidly polymerize with a low energy active energy ray, and the formed cured product has a high degree of crosslinking, excellent adhesion to a recording medium, and its viscosity is required for inkjet recording. Even in an ink jet recording system that satisfies the low viscosity level and has excellent storage stability with time, and the recording method gives thermal energy corresponding to the recording signal and generates ink droplets by the energy, An object of the present invention is to provide an ink jet recording method using an active energy ray-curable water-based ink that does not cause thermal polymerization and has excellent ejection stability that does not affect ink ejection.

  A fourth object of the present invention is to provide a recorded image, an ink cartridge, a recording unit, and an ink jet recording apparatus using the ink for ink jet recording.

  The above object is achieved by the present invention described below. That is, the present invention includes, as a first embodiment, at least water, a hydrophilic polymerizable compound 1, a hydrophilic polymerizable compound 2, and a hydrophilic polymerization initiator, and the hydrophilic polymerizable compound 1 and the hydrophilic polymerization. At least one of the polymerizable compounds 2 has two or more polymerizable groups, wherein the hydrophilic polymerizable compound 1 is a polymerizable substance having a maleimide group, and the hydrophilic polymerizable compound 2 is ethylenic. Provided is an active energy ray-curable liquid composition that is a hydrophilic polymerizable substance having an unsaturated bond.

  The active energy ray-curable aqueous composition preferably further contains a polymerization initiator that generates radicals by active energy rays; and further contains water. The polymerization initiator is preferably a water-soluble polymerization initiator.

  The present invention also provides, as a second embodiment, an active energy ray-curable ink comprising at least the active energy ray polymerizable substance of the present invention and a color material. The ink is suitable as an inkjet recording ink (hereinafter sometimes simply referred to as “ink”).

  In addition, as a third embodiment, the present invention provides a step of ejecting the ink of the present invention onto a recording medium, and irradiating the recording medium to which the ink is applied with active energy rays to cure the ink. There is provided an ink jet recording method comprising the step of: The ink jet recording method is preferably a method of applying the ink onto the recording medium by applying thermal energy to the ink.

According to a fourth embodiment of the present invention, there is provided a recorded image formed by the recording method of the present invention; and an ink container that stores the ink of the present invention. An ink cartridge comprising: an ink container containing the ink of the present invention; and a recording unit for discharging the ink; and the ink of the present invention There is provided an ink jet recording apparatus comprising: means for applying on a recording medium; and means for irradiating active energy rays to ink applied on the recording medium. In the apparatus, the means for irradiating the active energy rays is an ultraviolet irradiation lamp having a light source having a wavelength of 450 nm or less, and the irradiation intensity of the ultraviolet portion is in the range of 500 to 5,000 mW / cm ^2. preferable.

  According to the first embodiment of the present invention, an active energy ray curable type polymerized rapidly by a low energy active energy ray and having a high degree of crosslinking of the formed cured product and excellent adhesion to a substrate. An aqueous composition can be provided.

  According to the second embodiment of the present invention, the cured product formed by rapid polymerization with a low energy active energy ray has a high degree of cross-linking, and has high adhesion to a recording medium, low viscosity, and stability over time. It is possible to provide a hydrophilic active energy ray-curable ink that is also excellent.

  According to the third embodiment of the present invention, even in an ink jet recording method in which ink droplets are generated by applying thermal energy to ink, the ejection stability that does not affect ink ejection is excellent. An ink jet recording method using ink can be provided.

  Furthermore, according to the fourth embodiment of the present invention, a recording image formed by the recording method, an ink cartridge having the ink, a recording unit, and an ink jet recording apparatus can be provided.

FIG. 2 is a schematic view of the front of a suitable printer used in the present invention.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In view of the above-mentioned object, the present inventors have made at least water, a polymerizable substance represented by the hydrophilic polymerizable compound 1 having a maleimide group, and an ethylenically unsaturated bond in the course of various studies. An active energy ray-curable water-based ink containing a polymerizable substance represented by the hydrophilic compound 2 was prepared, and the active energy ray-curable water-based ink was evaluated. As a result, the active energy ray-curable ink having such a configuration is excellent in curing performance such as the degree of crosslinking and adhesiveness of a cured product even when irradiated with low energy active energy rays, and is further required for ink jet recording. It was found that the ink satisfies the viscosity level and is excellent in storage stability and ejection stability of the ink over time. And it came to make this invention.

  The reason why the excellent results of not only the curing performance but also the storage stability and ejection stability of the ink are obtained is not clear, but is considered as follows.

  Regarding the ink curing performance, the mechanism by which the curing performance of the aqueous composition and aqueous ink of the present invention is remarkably improved is estimated as follows. The hydrophilic polymerizable compound 1 of the present invention has a maleimide group. The maleimide group alone has a lower radical polymerization reactivity than conventional acrylic groups, but is excited by UV irradiation to generate radicals from the maleimide ring, which becomes the starting species and functions in addition to the originally contained photopolymerization initiator. In particular, it is considered that the polymerizing is facilitated by acting on the hydrophilic polymerizable compound 2 of the present invention. In the present invention, when the other hydrophilic polymerizable compound 2 has an electron donating group, since the maleimide group is an electron withdrawing group, a weak charge transfer complex is formed with the electron donating group, and this is irradiated with UV. It is considered that radicals are generated by this, which acts as a photopolymerization initiator and functions in addition to the originally contained photopolymerization initiator to copolymerize hydrophilic compound 1 and hydrophilic compound 2.

Further, it has recently been understood that a compound having a maleimide ring is less susceptible to oxygen inhibition, and the aqueous composition and ink jet ink of the present invention are less susceptible to oxygen inhibition of the polymerization reaction in addition to the excellent reactivity described above. It is presumed that it contributes to the curability of the water-based ink. Regarding the storage stability of the ink over time, the hydrophilic polymerizable compound 1 and the hydrophilic polymerizable compound 2 of the present invention have a conventional acrylic ester structure in an aqueous solution. Compared to the hydrophilic polymerizable substance it has, it is less susceptible to hydrolysis and produces very little acid. Therefore, the pH drop to the acidic region of the ink is suppressed, and aqueous dyes dissolved in water by anionic functional groups and aqueous pigment dispersions in which pigments are dispersed in water by anionic functional groups are stably dissolved. Or it can be dispersed. As a result, it is estimated that the ink has excellent storage stability over time.

  In addition, regarding the ink ejection stability, the hydrophilic polymerizable material represented by the general formula (I) has a resistance to thermal polymerization compared to a conventional hydrophilic polymerizable material having an acrylic ester structure, or hydrolysis. The amount of acid produced by is very small. As a result of suppressing the thermal polymerization of the curable composition by any of these, it is considered that the discharge stability is excellent.

  The action and effect in aqueous ink jet printing which is a main application example of the active energy ray polymerizable substance according to the present invention will be described below. As the active energy ray used in the present invention, ultraviolet rays, electron beams, and the like can be used. Hereinafter, ultraviolet curable inks that are radically polymerized and cured by particularly suitably used ultraviolet rays are listed as representative examples. Proceed with the explanation. However, the active energy ray used for curing in the present invention is not limited to ultraviolet rays.

The main purpose of using the active energy ray-curable ink according to the present invention as an aqueous ink for image recording used in the aqueous inkjet recording method is, for example, in the following points.
1) Increasing the drying property of ink and making it possible to cope with an improvement in printing speed. 2) A hydrophilic polymerizable substance is allowed to act as a binder of a coloring material so that an image having excellent scratch resistance can be formed on various recording media. 3) Light scattering from pigment particles is reduced, and a transparent ink layer can be formed. 4) As a result, the color reproduction range of the process color is expanded, and the ink is provided with an image forming ability that is high in density and excellent in saturation and brightness. 5) Further, it is possible to protect the color material from active light, gas components in the air, moisture, and the like.

  In particular, the ink of the present invention has a remarkable effect of improving the recording medium, such as plain paper, which has ink absorbability but it is difficult to improve the color of the pigment and to improve the scratch resistance. Is expected to do. Such effects are not limited to plain paper. For example, the same effects as with plain paper can be achieved for recording media with a low water-absorbing property such as offset printing paper, foam paper, and cardboard paper. To do. Furthermore, the ink of the present invention enables printing with a water-based ink on a non-absorbent printing substrate.

  The curing method using active energy rays is considered to be one of forced drying methods, and forms a free surface before ink applied on a recording medium such as paper penetrates into the recording medium. It can be said that this is a method of freezing the state in time. In the ink of the present invention, permeation and evaporation of a solvent component such as water gradually proceeds from the solidified ink layer. As described above, apparent drying occurs quickly. Therefore, the fixing time in the sense that the recording medium can be transported and stacked can be handled as being shortened. However, as long as the aqueous solvent is used, it is inevitable that the true drying is slower than the ink using the organic solvent. Therefore, when the ink of the present invention is used, it is possible to provide a final forced heat dryer depending on the application.

  As in the ink of the present invention, in the presence of moisture, how the curing of the hydrophilic polymerizable substance that undergoes radical polymerization by active energy rays proceeds purely as a problem of radical reaction rate. It is. According to the study by the present inventors, it has not been observed that a colorless ink having no coloring material has a particularly slow reaction in water polymerization compared to a solventless system. Of course, since the polymerized product contains water, the solid physical properties are different from those in the case of a solventless system.

Next, each constituent material of the active energy ray-curable ink of the present invention having the above-described excellent actions and effects will be described.
(Hydrophilic polymerizable substance)
The polymerizable substance used in the ink of the present invention is hydrophilic. That the polymerizable substance referred to in the present invention is hydrophilic means that the polymerizable substance is in the following state.
(1) Soluble in an organic solvent miscible with water, and the organic solvent solution is water-soluble (2) Even if the polymerizable substance itself is water-insoluble, it is treated in a form that can be emulsified in water. (3) Water-soluble One of the active energy ray polymerizable substances used in the ink of the present invention is the hydrophilic polymerizable compound 1 having a maleimide group. The hydrophilic polymerizable compound 1 preferably has one or more sites represented by the following general formula (I).

(Wherein A ₁ is selected from the group consisting of an optionally substituted ethylene oxide chain, an optionally substituted propylene oxide chain and an optionally branched substituted or unsubstituted alkylene group. Or at least one or a combination of two or more thereof.)
At least one of the active energy ray polymerizable substances further used in the ink of the present invention is a hydrophilic polymerizable compound 2 having an ethylenically unsaturated bond. The hydrophilic polymerizable compound 2 preferably has one or more sites represented by the following general formula (II).

(Wherein A ₂ is selected from the group consisting of an optionally substituted ethylene oxide chain, an optionally substituted propylene oxide chain and an optionally branched substituted or unsubstituted alkylene group. And B ₂ represents a moiety represented by the following general formula (III-1) or general formula (III-2).)

  (Here, X represents a cyclic linking group having a carbonyl group and a site comprising an unsaturated carbon bond adjacent to the carbonyl group.)

(Here, Y ₁ represents a hydrogen atom, a methyl group, or a halogen atom. D represents any one selected from the following group.)

(R ₂ , R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom, a methyl group or an ethyl group.)
Furthermore, the hydrophilic polymerizable compound 2 is preferably a compound having one or more sites represented by the following general formula (IV).

(Wherein A ₃ is selected from the group consisting of an optionally substituted ethylene oxide chain, an optionally substituted propylene oxide chain and an optionally branched substituted or unsubstituted alkylene group. D ₂ represents an electron donating group, and Y ₂ represents a hydrogen atom, a methyl group, or a halogen atom.)
The number of functional groups of the active energy ray polymerizable substance used in the present invention is preferably in the range of 2 to 6, more preferably in the range of 3 to 4, from the viewpoints of ink curing performance and low viscosity. It is. Curing performance improves as the number of polymerized functional groups in the hydrophilic polymerizable material increases, but the viscosity of the ink increases as the number of functional groups increases, and the flow characteristics corresponding to high-density nozzles of ink jet recording systems are good. It becomes difficult to obtain an active energy ray-curable ink. Further, when the active energy ray-polymerizable substance has a polymerization functional group of 1, the polymerization rate is slow and the degree of crosslinking of the cured product is extremely low, so that it is not suitable for the material of the active energy ray-curable aqueous ink of the present invention. The hydrophilic polymerizable substance used in the present invention may be a monofunctional monomer having a polymerization functional group of 1, but in this case, it is necessary to further contain an active energy ray polymerizable substance having a polymerizable functional group of 2 or more. is there.

The active energy ray polymerizable substance of the present invention includes an ethylene oxide chain / propylene oxide chain or a hydroxyl group contained in each group of A ₁ , A ₂ , and A _{3 in} the general formulas (I), (II), and (IV). Imparts hydrophilicity. The number of ethylene oxide chains or propylene oxide chains contained in each group of A ₁ , A ₂ , and A ₃ is preferably in the range of 0 to 5, more preferably in the range of 1 to 3. _Further, A _1, A 2, total number of the number and propylene oxide units ethylene oxide units in _{A 3} is preferably a 1-6. In addition, the ethylene oxide unit and the propylene oxide unit in the present invention are specifically units represented by the following structural formula. If the ethylene oxide chain or the propylene oxide chain in the active energy ray polymerizable substance is short, the hydrophilicity is lowered. On the other hand, when the ethylene oxide chain or propylene oxide chain is long, hydrophilicity can be obtained, but solid physical properties when polymerized or cured may be insufficient in performance such as hardness and adhesiveness.

  In the present invention, it is preferable that the hydrophilic polymerizable compound 1 and the hydrophilic compound 2 each independently have a polyol residue. A polyol residue is obtained by removing two or more hydroxyl groups from a polyol. Preferred polyols include the following.

  Specifically, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3 -Butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, glycerin, 1,2,4-butanetriol, 1,2, 6-hexanetriol, 1,2,5-pentanetriol Thiodiglycol, trimethylol propane, ditrimethylolpropane, trimethylolethane, di-trimethylolpropane, neopentyl glycol, pentaerythritol, dipentaerythritol and their condensates.

  Examples of other polyols include the following.

  Specifically, for example, low molecular weight polyvinyl alcohol and triose, tetrose (erythritol, threitol), pentose (ribitol, arabinitol, xylitol), hexose (allitol, alitolitol, glucitol, mannitol, iditol, galactitol, inositol), Examples thereof include monosaccharides such as heptose, octose, nonose, and decos, and their deoxy sugars, aldonic acid, and aldaric acid derivatives. Of course, the polyol used in the present invention is not limited to these.

  Among these polyols, the following are particularly preferable. Specifically, for example, glycerin, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,2,5-pentanetriol, trimethylolpropane, trimethylolethane, neopentylglycol, penta Erythritol is mentioned.

  Specific preferred specific examples of the hydrophilic polymerizable compound 1 and the hydrophilic polymerizable compound 2 include, for example, active energy ray polymerizable substances having the structures shown below, and the active energy ray polymerization used in the present invention. The sex substance is not limited to these. These compounds are hydrophilic, have polymerizability, have a high polymerization rate, have a low viscosity per se, and have a viscosity in the case of an aqueous solution as compared with conventionally known compounds. The viscosity becomes extremely low.

  In the present invention, two or more kinds of active energy ray polymerizable substances disclosed in the present specification can be used in combination. For example, the hydrophilic polymerizable compound 2 will be described in relation to exemplary compounds II-11 and II-12, which will be described later. For these compounds, N-vinylamide bonds are exemplified as terminal groups having radical polymerizability. In the present invention, when creating an active energy ray-curable ink, an ink design considering various viewpoints may be required. For example, there is a problem of ink viscosity and polymerized film strength, and for this, for example, it is possible to achieve such a balance by mixing exemplary compounds 1 and 2. In some cases, a monofunctional monomer having one N-vinylamide bond introduced in Exemplified Compound 1 may be used in the ink. Or you may combine the compound which has another terminal group, for example, the monomer which made the reactive terminal group vinyl sulfone.

  As described above, the polyfunctional monomer or the monofunctional monomer that can be combined in the present invention is not particularly limited as long as it is a compound within the range disclosed in the present invention. Further, there is no particular problem even if a conventionally known hydrophilic monomer or water-dispersible monomer is combined with the polymerizable substance of the present invention within the scope of the present invention.

  Specific example of hydrophilic polymerizable compound 1

  Regarding the position where the maleimide group enters the terminal, when the carbon of the glycerin residue is 1, 2, and 3 from the top, Example Compound I-3 shows the terminal of 1 and 3 carbons. It may be 2 (2 and 3) carbon. Regarding the fact that such substituent isomers fall within the category of exemplary compounds, this applies to all the exemplary compounds below, regardless of the number of substituents.

  Specific example of hydrophilic polymerizable compound 2

  Among the hydrophilic polymerizable compounds 2 presented in the specific examples, Exemplified Compounds II-11, II-12, II-15, II-16, II-19, II-21 are particularly preferable, and Exemplified Compound II- 11, II-12, II-19 and II-21 are preferred.

The active energy ray polymerizable substance represented by the general formula (I) of the present invention is produced by the following method.
<Synthesis method>
For example, Japanese Patent Publication Nos. 44-29622, 47-24259, 47-25373, Japanese Patent Laid-Open Nos. 49-24435, 53-41221 can be used for synthesizing a compound having a vinylsulfone bond. No. 59-18944, JP-A-11-231488, and the like. Further, methods for synthesizing a compound having a vinyl ketone bond are described in, for example, JP-B-1-2095, JP-A-2-110114, JP-A-7-291886, and JP-A-2004-189715.

A method for synthesizing a compound having a vinyl ether bond is described, for example, in J. Org. of American Chemical Society, 2828 79 (5) (1957), 2833 79 (5) (1957), Tetrahedorn 233, 28 (1978), and the like. Moreover, the compound which has a vinylamide bond is described in Unexamined-Japanese-Patent No. 8-81428, Unexamined-Japanese-Patent No. 2002-167369, etc., for example. Compounds having an N-vinylpyrrolidone bond are described in, for example, JP-A-6-145410 and Japanese Patent No. 2939433. The polymerizable substance of the present invention can be synthesized with reference to the above literature.
(Hydrophilic polymerization initiator)
The polymerization initiator used in the present invention is hydrophilic. That the compound referred to in the present invention is hydrophilic means that the compound is in the following state. (1) Soluble in an organic solvent miscible with water, and the organic solvent solution is water-soluble (2) Even if the compound itself is water-insoluble, it is treated in a form that can be emulsified in water (3) Water-soluble The hydrophilic polymerization initiator used in the present invention may be any compound as long as it is a compound that generates radicals by active energy rays, but the following general formulas (2) and (4) to It is preferably at least one compound selected from the group consisting of (7).

R ₂ in the above formula represents an alkyl group or a phenyl group, R ₃ represents an alkyloxy group or a phenyl group, and R ₄ represents the following general formula (3).

R ₅ in the above formula represents — [CH ₂ ] _{x 2} — (x ₂ is 0 or 1) or a phenylene group, m 2 represents an integer of 0 to 10, n 2 represents 0 or 1, and R ₆ represents A hydrogen atom, a sulfone group, a carboxyl group, a hydroxyl group or a salt thereof is shown.

  M3 in the above formula represents an integer of 1 or more, n3 represents an integer of 0 or more, and m3 + n3 represents an integer of 1 to 8.

R ₁₀ and R ₁₁ in the above formula each independently represent a hydrogen atom or an alkyl group, and m4 represents an integer of 5 to 10.

R ₁₀ and R ₁₁ in the above formula each independently represent a hydrogen atom or an alkyl group, and R ₁₂ represents — (CH ₂ ) _x — (x is 0 or 1), —O— (CH ₂ ) _y —. (Y represents 1 or 2) or a phenylene group, and M represents a hydrogen atom or an alkali metal.

Each independently R ₁₀ and R ₁₁ in the formula is a hydrogen atom or an alkyl group, M represents a hydrogen atom or an alkali metal.

  In these, it is preferable that it is a compound shown by General formula (2), (4) and (5), and it is especially preferable that it is a compound shown by General formula (2) and (4).

The alkyl group and phenyl group R ₂ in the general formula (2) may have a substituent. Examples of such substituents include the following.

Specifically, for example, halogen, a lower alkyl group having 1 to 5 carbon atoms, a lower alkyloxy group having 1 to 5 carbon atoms, a group represented by the general formula (3), a sulfone group, a carboxyl group, a hydroxyl group, and Examples thereof include a salt of a sulfone group, a carboxyl group, or a hydroxyl group (—SO ₃ M, —CO ₂ M, —OM). Particularly preferred R ₂ is a phenyl group having a lower alkyl group having 1 to 5 carbon atoms as a substituent.

M is independently a hydrogen atom, an alkali metal, an alkaline earth metal, or ammonium represented by HNR ₇ R ₈ R ₉ (R ₇ , R ₈ , R ₉ are each independently a hydrogen atom, carbon number 1 A lower alkyl group of ˜5, a monohydroxyl-substituted lower alkyl group of 1 to 5 carbon atoms or a phenyl group).

Moreover, the phenylene group of R ₅ in the general formula (3) may have a substituent. Examples of such substituents include the following.

Specifically, for example, halogen, lower alkyl group having 1 to 5 carbon atoms, lower alkyloxy group having 1 to 5 carbon atoms, sulfone group, carboxyl group, hydroxyl group and sulfone group, carboxyl group, hydroxyl group salt ( _{-SO 3 M, -CO 2 M,} -OM) can be mentioned.

M is independently a hydrogen atom, an alkali metal, an alkaline earth metal, or ammonium represented by HNR ₇ R ₈ R ₉ (R ₇ , R ₈ , R ₉ are each independently a hydrogen atom, carbon number 1 A lower alkyl group of ˜5, a monohydroxyl-substituted lower alkyl group of 1 to 5 carbon atoms or a phenyl group).

Examples of the salt of R ₆ in the general formula (3) include —SO ₃ M, —CO ₂ M, and OM. Such M is each independently a hydrogen atom, an alkali metal, an alkaline earth metal or ammonium represented by HNR ₇ R ₈ R ₉ (R ₇ , R ₈ , R ₉ are each independently a hydrogen atom, 5 represents a lower alkyl group, a monohydroxyl-substituted lower alkyl group having 1 to 5 carbon atoms, or a phenyl group.).

The alkyloxy group and phenyl group of R3 in the general formula (2) may have a substituent. Examples of the substituent include halogen, a lower alkyl group having 1 to 5 carbon atoms, and 1 to 5 carbon atoms. A lower alkyloxy group may be mentioned. Particularly preferred R ₃ is an alkyloxy group, among them —OC ₂ H ₅ and OC (CH ₃ ) ₃ .

The alkyl groups of R ₁₀ and R _{11 in} the general formulas (5) to (7) may have a substituent. Examples of such substituents include the following.

Specific examples include halogens, sulfone groups, carboxyl groups, hydroxyl groups and sulfone groups, carboxyl groups, and hydroxyl group salts (—SO ₃ M, —CO ₂ M, —OM).

M is independently a hydrogen atom, an alkali metal, an alkaline earth metal, or ammonium represented by HNR ₇ R ₈ R ₉ (R ₇ , R ₈ , R ₉ are each independently a hydrogen atom, carbon number 1 A lower alkyl group of ˜5, a monohydroxyl-substituted lower alkyl group of 1 to 5 carbon atoms or a phenyl group).

  Particularly preferred specific examples of these hydrophilic polymerization initiators include, for example, hydrophilic polymerizable substances having the structure shown below, but the hydrophilic polymerization initiator used in the present invention is limited to these. is not.

  In the present invention, when a thioxanthone-based hydrophilic polymerization initiator or the like is used as the hydrophilic polymerization initiator, it is preferable to add a hydrogen donor. Examples of the hydrogen donor that can be used in the present invention include, but are not limited to, triethanolamine and monoethanolamine.

In the present invention, two or more hydrophilic polymerization initiators can be used in combination. By adding two or more types of hydrophilic polymerization initiators, generation of further radicals can be expected using light having a wavelength that cannot be effectively used with one type of hydrophilic polymerization initiator. Further, the hydrophilic polymerization initiator as described above is not always necessary when an electron beam curing method in which an ink is cured using an electron beam as an active energy ray.
(Aqueous pigment dispersion)
The active energy ray-curable ink according to the present invention is a colored active energy ray-curable ink or an active energy ray-curable paint that is cured by irradiation with an active energy ray or the like by containing a pigment as a colorant. Can be used. At this time, it is preferable to use an aqueous pigment dispersion in which a pigment is uniformly dispersed in an aqueous medium as a coloring material. As the aqueous pigment dispersion, it is particularly preferable to use an aqueous pigment dispersion in which a pigment is stably dispersed in water by an anionic functional group. For example, water-based gravure inks that are stable in nonionic or anionic systems, pigment dispersions for aqueous writing instruments, pigment dispersions for conventionally known ink jet recording inks, and the like can be applied as they are.

  Examples of pigment dispersions having an anionic dissociating group and dispersed using an alkali-soluble hydrophilic polymer are disclosed in, for example, JP-A Nos. 5-247392 and 8-143802. A pigment dispersion dispersed with a surfactant having an anionic dissociating group is disclosed in JP-A-8-209048. Further, the following publications disclose the pigment dispersion encapsulated with a polymer and dispersed by providing an anionic dissociation group on the surface thereof. For example, they are disclosed in JP-A-10-140065, JP-A-9-316353, JP-A-9-151342, JP-A-9-104834, and JP-A-9-031360. Further, as a pigment dispersion in which a pigment is dispersed by bonding an anionic dissociative group to the pigment surface by a chemical reaction, US Pat. No. 5,837,045 and US Pat. No. 5,851,280 are disclosed. There are dispersions as disclosed in the literature. In the ink of the present invention, any of the various pigment dispersions described above can be used as the ink coloring material.

  The active energy ray-curable ink according to the present invention is not limited to the pigment as described above, and a dye may be used as a coloring material, and an ink having a water-soluble dye in a dissolved state may be used by active energy ray irradiation. This is possible as long as fading is not a practical problem. Further, a color material dispersion containing a disperse dye, an oil-soluble dye, or the like in a dispersed state can be applied in the same manner as the above-described pigment dispersion. These are appropriately selected according to the application.

When a pigment is used as the coloring material of the ink according to the present invention, it is necessary to use a pigment dispersion in which the pigment is dispersed in a fine particle state in the medium. In particular, a pigment dispersion that can be suitably used for ink needs to have the following basic elements. Specifically, the pigment is dispersed in an aqueous medium, the particle size distribution as a dispersion is in the range of 25 nm to 350 nm in average particle diameter, and the viscosity of the final ink can be adjusted to a range that does not affect ejection. Is required. Furthermore, it is necessary that the compatibility with the above-described aqueous active energy ray-curable polymer of the present invention, which is essential for making the ink active energy ray-curable, is satisfied. Below, each constituent material which can be used for the pigment dispersion suitable in this invention is demonstrated.
<Pigment>
As the organic pigment having a hue as a process color used in the color ink, the following can be appropriately used. Examples of color index (CI) numbers include the following.

C. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 55, 74, 83, 86, 93, 97, 98, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185
C. I. Pigment Orange 16, 36, 43, 51, 55, 59, 61, 71
C. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 192, 202, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 272
C. I. Pigment Violet 19, 23, 29, 30, 37, 40, 50
C. I. Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64
C. I. Pigment Green 7, 36
C. I. Pigment Brown 23, 25, 26
<Particle diameter of pigment in ink>
The average particle diameter of the pigment particles is in the range of about 25 nm to 350 nm, preferably in the range of 70 nm to 200 nm. Although this range depends on the use of the printed matter, it is sufficiently smaller than the wavelength of visible light, so that it can be said that the printed matter can be said to be sufficiently transparent if the light scattering is small.
<Dye>
For example, in the case of the active energy ray-curable ink according to the present invention, after the ink is attached to a recording medium (such as recording paper), the active energy ray-curable polymer in the ink is polymerized by the active energy ray. It is preferable to cure. As described above, when a dye is used as a coloring material, unlike the case of using the above-described pigment, it is difficult to use in a state in which fading due to active energy ray irradiation is small, and there is a slight fading. For this reason, when a dye is applied as the coloring material of the ink, it is preferable to use a so-called azo metal-containing dye in which a complex is formed with metal ions because the fading due to light is small. However, if the level of fading is not a problem, even a general hydrophilic dye can be used at least as an ink.

  On the premise of this, the dye species applicable in the sense of having a process color color are the following compounds. Examples of color index (CI) numbers include the following.

C. I. Acid Yellow 11, 17, 23, 25, 29, 42, 49, 61, 71
C. I Direct Yellow 12, 24, 26, 44, 86, 87, 98, 100, 130, 132, 142
C. I Acid Red 1, 6, 8, 32, 35, 37, 51, 52, 80, 85, 87, 92, 94, 115, 180, 254, 256, 289, 315, 317
C. I Direct Red 1, 4, 13, 17, 23, 28, 31, 62, 79, 81, 83, 89, 227, 240, 242, 243
C. I Acid Blue 9, 22, 40, 59, 93, 102, 104, 113, 117, 120, 167, 229, 234, 254
C. I Direct Blue 6, 22, 25, 71, 78, 86, 90, 106, 199
A preferable content of the dye in the ink is 0.1% by mass to 10% by mass based on the total mass of the ink. When the content of the dye is low, it is preferably applied to, for example, a so-called light ink of density modulation ink.
<Prescription for clear ink>
The active energy ray-curable ink according to the present invention can be a clear ink by forming a transparent ink without containing the above-described coloring material. In particular, when prepared so as to have ink jet recording characteristics, an active energy ray-curable clear ink for ink jet recording can be obtained. If such an ink is used, a clear film can be obtained because it does not contain a color material. Applications of clear inks that do not contain color materials include the following. For example, it can be used as an undercoat for imparting suitability for image printing to a recording medium, or as an overcoat for the purpose of surface protection of images formed with ordinary ink, further decoration and glossiness, etc. Etc. In the clear ink, colorless pigments or fine particles that are not intended for coloring can be dispersed and contained in accordance with uses such as oxidation prevention and fading prevention. By adding these, in any of the undercoat and overcoat, various properties such as the image quality, fastness, and workability (handling property) of the printed matter can be improved.

When applied to such clear ink, the content of the active energy ray polymerizable substance is preferably 10% by mass to 70% by mass based on the total mass of the ink. Moreover, 1-10 mass parts of hydrophilic polymerization initiators (for example, active energy ray polymerization catalyst) are contained with respect to 100 mass parts of the above-mentioned polymerizable substances, and at the same time, hydrophilic polymerization initiator with respect to 100 mass parts of ink. Is preferably prepared so as to contain at least 0.5 parts by mass.
<Reactive diluent component>
As described above, when the active energy ray-curable ink according to the present invention is used as a clear ink, a polymerization-reactive low-viscosity monomer can be contained as a solvent. The advantage of using these substances rather than ordinary solvents is that these substances do not remain as plasticizers in the solid after reaction cured with active energy rays, so the effect on the physical properties of the solid is reduced. There is. Examples of reactive diluent components selected for such purposes include the following.
Specifically, for example, acryloylmorpholine used in the above-listed examples, N-vinyl pyrrolidone, acrylamide, methylene bisacrylamide, monosaccharide monoacrylate, oligoethylene oxide monoacrylate, and dibasic acid Examples include compounds such as monoacrylic acid esters.
<Solvent component>
Furthermore, when the active energy ray-curable ink according to the present invention is used as a clear ink, it is particularly preferable not to use a solvent that imparts moisture retention, such as those conventionally used in water-based inkjet recording inks. . This is because the clear ink does not contain a solid component such as a pigment, so the viscosity is small and it can be easily recovered even if there is a slight viscosity increase. Of course, solvents having higher moisturizing properties as described later can be added to the minimum necessary level. These can be selected from a large number of compounds conventionally used in aqueous inkjet.

  When the active energy ray-curable ink according to the present invention is used as an ink containing a color material, a solvent component can be added to the ink. The solvent component is added for the purpose of imparting non-volatility to the ink, lowering the viscosity, and imparting wettability to the printing substrate. In the case of printing on a non-absorbent substrate, it is preferable not to include the solvent component in the ink but to include only water so that all of the polymerizable substance component is cured and solidified. .

  When the solvent component is added to the ink in an amount of 10% by mass or more, in the sense of the strength of the finally obtained ink film, the printed material (recording medium) that forms an image has a certain absorbency. It is necessary to be. That is, in the case of printing with water-based gravure ink, a recording medium imparted with constant wettability and permeability is used and forced drying is performed. Also in the ink according to the present invention, when the solvent component is added to the ink in an amount of 10% by mass or more, for example, a pretreatment for imparting water-based ink acceptability to the recording medium is performed, and the ink is cured with active energy rays. After that, it is preferable to perform natural or forced drying treatment. Since the various hydrophilic polymerizable substances disclosed in the present invention themselves have a certain moisturizing property (inhibition of water evaporation, water absorption), it is possible to form an ink without a solvent. In this case, measures such as capping, ink suction at the start of printing, and idle ejection may be used to ensure printing reliability at a practical level.

Listed below are hydrophilic organic solvents which can be used in the ink of the present invention and which can be evaporated and dried relatively easily. In the ink of the present invention, a solvent arbitrarily selected from the following organic solvents can be added. Specifically, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoallyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl Examples include ethers, glycol ethers such as propylene glycol monomethyl ether and dipropylene glycol monomethyl ether, and monohydric alcohols.
<Material structure of colorant-containing ink>
When the active energy ray-curable ink according to the present invention is used for an ink containing a color material, the concentration of the catalyst and the active energy ray polymerizable substance in the ink is adjusted according to the absorption characteristics of the contained color material. It is preferable to adjust. The blending amount is preferably 40% to 90% by weight, particularly preferably 60% to 75% by weight, based on the total weight of the ink. Further, the content of the active energy ray polymerizable substance in the ink is preferably 1% by mass to 35% by mass, and particularly preferably 10% by mass to 25% by mass, based on the total mass of the ink. . The polymerization catalyst depends on the content of the active energy ray polymerizable substance, but is generally preferably 0.1% by mass to 7% by mass, particularly 0.3% by mass based on the total mass of the ink. It is preferable to set it as -5 mass%.

  When a pigment is used as the ink coloring material, the concentration of the pure pigment in the ink is preferably about 0.3% by mass to 10% by mass based on the total mass of the ink. The coloring power of the pigment also depends on the dispersion state of the pigment particles, but when the concentration of the pure pigment component is about 0.3% by mass to 1% by mass, the range is used as a light color ink. On the other hand, if it is more than that, it gives a concentration used for general color coloring. The concentration of the pigment dispersion also depends on the viscosity and flow characteristics required by the printing apparatus.

  Regarding the viscosity of the ink, in the case of an on-demand ink jet apparatus, there is no nonlinearity in a wide range of viscosity, and the upper limit is 15 mPa · s. In the case where the ink dots are fine high density and high drive frequency nozzles, the upper limit is 10 mPa · s.

  The surface tension is preferably 35 mN / m (dyne / cm) or more in consideration of printing the ink according to the present invention on plain paper. In order to sufficiently suppress the bleed phenomenon between colors in printing on plain paper, in ordinary inkjet recording ink, the surface tension is adjusted to a low value of about 30 mN / m, and the ink droplets are reduced for a short time. It is necessary to penetrate into the recording medium. However, this case is accompanied by a decrease in image density.

On the other hand, in the active energy ray-curable ink according to the present invention, it is preferable that the surface tension is as high as possible so that ink droplets stay on the surface of the recording medium as much as possible when the active energy is irradiated. Ink droplets are effectively cured on the surface of the recording medium, bleed can be sufficiently suppressed, and a high image density can be obtained at the same time. In order to secure this image density, on the other hand, it is necessary that the ink droplets are wetted to the recording medium to some extent when the active energy is irradiated, so the upper limit of the surface tension is preferably about 50 mN / m. preferable.
<Printer system>
The ink of the present invention is used for an ink jet discharge type head, and is also effective as an ink storage container in which the ink is stored or as a filling ink. In particular, the present invention provides an excellent effect in a bubble jet (registered trademark) type recording head and recording apparatus among ink jet recording methods.

  As for the typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferable. . This method can be applied to both a so-called on-demand type and a continuous type. In the case of the on-demand type, at least one that gives a rapid temperature rise exceeding the nucleate boiling corresponding to the recording information to the electrothermal transducer disposed corresponding to the sheet or liquid path holding the ink. One drive signal is applied. This is effective because heat energy is generated in the electrothermal transducer, and the film is boiled on the heat acting surface of the recording head. As a result, the drive signals can be made to correspond one-to-one and bubbles in the ink can be formed. By the growth and contraction of the bubbles, ink is ejected through the ejection openings to form at least one droplet. It is more preferable that the drive signal has a pulse shape, because the bubble growth and contraction is performed immediately and appropriately, and thus ink discharge with particularly excellent responsiveness can be achieved. As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.

  As the configuration of the recording head, a combination configuration (straight liquid flow path or right-angle liquid flow path) of an ejection port, a liquid path, and an electrothermal transducer as disclosed in the above specifications is effective. In addition to this, a configuration using US Pat. No. 4,558,333 and US Pat. No. 4,459,600 which disclose a configuration in which the heat acting portion is arranged in a bent region is also effective. . Alternatively, the present invention is also effective for the discharge method of the atmospheric communication method described in Japanese Patent No. 2968280, Japanese Patent No. 3246949, and Japanese Patent Application Laid-Open No. 11-188870. In addition, the present invention is also effective for a configuration in which a common discharge hole is used as a discharge portion of an electrothermal transducer for a plurality of electrothermal transducers (JP 59-123670 A, etc.). . Furthermore, the above-described effects can be more effectively exhibited for a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus. Specifically, a configuration in which the length is satisfied by a combination of a plurality of recording heads as disclosed in the above-described specification, or a configuration as a single recording head formed integrally can be employed.

  In addition, it is mounted on the main body of the device so that it can be electrically connected to the main body of the device and supplied with ink from the main body of the device. The present invention is also effective for a cartridge type recording head. In the present invention, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc. provided as the configuration of the recording apparatus to be applied, because the effects of the present invention can be further stabilized. . Specific examples thereof include a capping unit for the recording head, a cleaning unit, a pressure or suction unit, an electrothermal converter, a heating element different from this, or a preheating unit using a combination thereof, This is a preliminary ejection mode in which ejection different from recording is performed.

  Further, the recording apparatus of the present invention is specifically shown using a schematic view of the front of the printer in FIG. Such a recording apparatus includes an ink tank unit 1 that contains an active energy ray-curable aqueous ink, a head unit 2 that performs recording, a lamp unit 3 that performs ultraviolet irradiation for curing, and a drive unit 4 that drives the head unit and the lamp unit. A paper discharge unit 5 for conveying the recording medium is provided. The head unit 2 uses a multi-head in which a large number of heads are arranged. In addition to these, a wiping unit, a capping unit, a paper feeding unit, and a drive motor unit (not shown) are provided.

  In FIG. 1, the head portion 2 has nozzle portions for discharging active energy ray-curable water-based ink arranged symmetrically for each color. The head unit 2 and the lamp unit 3 are integrally scanned left and right, and after applying the active energy ray-curable water-based ink to the recording medium, the active energy irradiation is immediately performed (preferably used as the active energy). Details of the ultraviolet lamp to be obtained will be described later). Therefore, when this recording apparatus is used, an ink jet recording method capable of suppressing bleeding of ink droplets and bleeding between colors in recording on plain paper, and realizing high-quality and high-definition image formation can be obtained.

  The ink tank unit 1 is arranged with four colors of black (Bk), cyan (C), magenta (M), and yellow (Y), but light cyan (LC) is used to record a higher-definition image. ) Or light magenta (LM). Further, since the reactivity of black is inferior to that of other colors, a three-color arrangement that forms a process black combining cyan, magenta, and yellow may be used. In the present invention, a tank that can block light is used.

In the present invention, in addition to the recording system described above, a lamp is disposed on the front surface of the paper discharge unit, a paper supply / discharge process is performed around a rotating drum, and a drying unit is provided separately. Can be selected as appropriate.
<Ultraviolet irradiation lamp>
The ultraviolet irradiation lamp used for curing the active energy ray-curable ink particularly suitable in the present invention will be described below. The ultraviolet irradiation lamp is preferably a so-called low-pressure mercury lamp, high-pressure mercury lamp, mercury lamp coated with a phosphor, or the like whose mercury vapor pressure is 1 to 10 Pa during lighting. The ultraviolet region emission spectrum of these mercury lamps is 450 nm or less, particularly in the range of 184 nm to 450 nm, and is suitable for efficiently reacting a polymerizable substance in black or colored ink. Also, a small power supply can be used for mounting the power supply in the printer, which is also suitable in that sense. As the mercury lamp, for example, a metal halide lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon flash lamp, a deep UV lamp, a lamp that uses a microwave to excite a mercury lamp from the outside, and a UV laser are practically used. Since these mercury lamps include the above-mentioned range as the emission wavelength region, they are basically applicable as long as power source size, input intensity, lamp shape, etc. are allowed. The light source is selected according to the sensitivity of the catalyst used.

The necessary UV intensity is preferably about 500 to 5,000 mW / cm ^{2 from} the viewpoint of the polymerization rate. If the irradiation intensity is insufficient, the curing of the present invention cannot be obtained sufficiently. On the other hand, if the irradiation intensity is too strong, the printing substrate may be damaged or the color material may be faded.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited by the following examples unless it exceeds the gist.

<Examples 1 to 5 and Comparative Examples 1 and 2>
The components shown in Table 1 and Table 2 were mixed, sufficiently stirred, and filtered under pressure using a 1.2 micron filter to prepare liquid compositions of Examples 1 to 5 and Examples 1 and 2. Unless otherwise specified, the amount of a component in each liquid composition means “parts by mass”.

<Evaluation of film formability of aqueous composition>
Using the aqueous composition shown in Table 1, the film formability was evaluated as follows. A commercially available PET (polyethylene terephthalate) film was coated with the liquid compositions of Examples 1 to 12 at 5 g / m ² using a bar coater. The PET film thus coated was applied to a UV irradiation apparatus. As the UV lamp used, FUSION UV Systems Inc. A UV curable evaluation apparatus model LH6B manufactured by the company was used. The irradiation intensity was examined under the following three conditions. A: 1500mW / cm ^2, the condition B: 1000mW / cm ^2, the condition B: 500mW / cm ^2, the conveying speed was 0.4 m / sec. The pencil hardness of the film thus formed was measured with a commercially available pencil hardness tester. The measurement results are summarized in Table 2. Pencil hardness measurement conforms to JIS.

  As shown in Table 2, when the aqueous composition of the present invention was used, the curability did not change even under low irradiation conditions, and a pencil hardness with no practical problem was obtained.

<Examples 6 to 10 and Comparative Examples 3 and 4>
A cyan pigment dispersion was prepared as follows. Pigment Blue 15: 3 was used as a pigment, and a random polymer of styrene / acrylic acid / ethyl acrylate (average molecular weight: 3,500, acid value: 150) was used as a dispersant. These were dispersed by a bead mill, and finally a cyan pigment dispersion having a solid content of 10% by mass and a pigment / binder ratio of P / B = 3: 1 was obtained. The average particle size of the pigment was 120 nm. The average particle size of the pigment was measured using a laser light scattering type particle size measuring device.

  Next, after mixing the compounds having the composition shown in Table 3 and stirring sufficiently, pressure filtration was performed using a filter having a pore size of 0.50 μm to prepare inks used in Examples 6 to 10 and Comparative Examples 3 and 4. did. The pH of the ink was adjusted using a 0.2 N aqueous sodium hydroxide solution so that the pH was finally 8.5.

The ink prepared as described above was evaluated in the following manner.
[Evaluation printer]
An on-demand type ink jet recording apparatus Pixus 550i (manufactured by Canon Inc.) that discharges ink by applying thermal energy corresponding to the recording signal to the ink has been modified to have the same configuration as that shown in FIG. . Specifically, a UV lamp that excites a mercury lamp without an electrode from the outside using a microwave adjacent to the recording head portion was mounted. This printer was used for evaluation according to the evaluation methods and evaluation criteria described in (1) to (3) below. The UV lamp used a D bulb. The intensity at the irradiation position was 1500 mW / cm ² . Irradiation conditions were the following three conditions of integrated irradiation energy. The evaluation results are shown in Table 4. ("PIXUS" is a registered trademark)
D: 800 mJ / cm ²
E: 400 mJ / cm ²
F: 100 mJ / cm ²
(1) Ink curing performance 100% solid printing was performed on a PET film using each of the cyan inks of Examples 6 to 10 and Comparative Examples 3 and 4 and the printer. In the present invention, printing in which one pixel of an image formed at 600 × 600 dpi is completely filled with about 5 pl dots is called 100% solid.

The pencil hardness of the film thus formed was measured with a commercially available pencil hardness tester in the same manner as in Examples 1 to 5 and Comparative Example 1.
(2) Discharge stability The above-described printer was filled with predetermined ink, and horizontal ruled lines were continuously printed on PPC paper (manufactured by Canon), and the thickness of the lines and the landing positions of the dots were visually evaluated. .

A: There is no change in the thickness of the battle of the line, and there is almost no twist.

C: There is a thin line, and some twisting is observed. (3) Ink storage stability A predetermined ink was put into a Teflon (registered trademark) container and sealed. This was stored in an oven at 60 ° C. in the dark for 1 month. The average particle diameter of the pigment before and after storage was compared and evaluated according to the following criteria.

A: Change in average particle size is within ± 10% before and after storage B: Change in average particle size is within ± 15% before and after storage C: Change in average particle size exceeds 15% before and after storage

  As shown in Table 4, when the ink of the present invention was used, the curability did not change even under low irradiation conditions, and a pencil hardness with no practical problem was obtained. The ink of the present invention was excellent in ejection stability and stability over time.

<Examples 11, 12, and 13 Comparative Examples 5, 6, and 7>
Example 11, Comparative Example 5: Evaluation of Yellow Ink Example 12, Comparative Example 6: Evaluation of Magenta Ink Example 13, Comparative Example 7: Evaluation of Red Printed Portion Next, cyan dispersion used in Examples 6 to 10 A yellow and magenta dispersion was prepared in the same manner as the above.

(Preparation of yellow dispersion)
A yellow dispersion having a solid content of 10% by mass, P / B = 3/1, and an average particle size of 130 nm was prepared in the same manner as the preparation of the cyan dispersion except that Pigment Yellow 13 was used as the pigment.

(Preparation of magenta dispersion)
A magenta pigment dispersion having a solid content of 10% by mass, P / B = 3/1, and an average particle size of 125 nm was prepared in the same manner as the cyan dispersion, except that Pigment Red 122 was used as the pigment.

  Next, a yellow ink of Example 11 was produced in the same manner except that the cyan dispersion of Example 9 was replaced with the yellow dispersion produced above. Next, a magenta ink of Example 12 was produced in the same manner except that the cyan dispersion of Example 9 was replaced with the magenta dispersion produced above.

  Further, as a comparative example, the composition of Comparative Example 3 was used, and the yellow ink of Comparative Example 5 and the magenta ink of Comparative Example 6 were prepared using a yellow dispersion and a cyan dispersion as in Examples 11 and 12.

  In addition to the yellow and magenta inks produced above, the cyan ink used in Example 9 was combined to provide an ink set used in Examples 11-13. Using this ink set, the same printer as that used in Example 9 was used. On the PET film and Mitsubishi paper offset printing paper OK Kanto, yellow, magenta 100% solid printing, yellow 100% solid, magenta 100% solid The secondary color red of Example 13 and Comparative Example 7 to be formed was printed. In the present invention, printing in which one pixel of an image formed at 600 × 600 dpi is completely filled with about 5 pl dots is called 100% solid. Further, the UV irradiation was performed in the same manner as in the condition E of Example 9. For the yellow, magenta, and red portions of the image thus formed, the PET film printed matter was subjected to a pencil hardness test in the same manner as in Example 9. The above-described offset printing paper was subjected to the following fixability test. Furthermore, the following marker resistance test was performed using the yellow ink and magenta ink thus prepared. In addition, a discharge stability test and an ink storage stability test were performed using the yellow ink and the magenta ink thus prepared. The results are shown in Table 7.

Fixability test 10 seconds after printing, the sample was placed on a printed recording medium, and the sylbon paper was pulled with a load of 40 g / cm ² on the recording surface. It was visually observed whether or not the non-printed part (white background part) of the recording medium and the printed part of the Sylbon paper were smudged, and evaluated according to the following criteria.

A: No part due to rubbing B: Almost no dirt due to rubbing C: Contaminant part due to rubbing is conspicuous ・ Marker resistance Yellow ink, magenta ink of each of Examples 11 and 12 and Comparative Examples 5 and 6 Using the printer, 12-point characters were printed on Canon PPC paper. 1 minute after printing, the above-mentioned sample was marked once with a normal writing pressure using a fluorescent pen spotlight yellow manufactured by Pilot, and visually observed for the presence or absence of disorder of the characters, and evaluated according to the following criteria. .

A: Character disorder due to the marker does not occur B: Character disorder due to the marker slightly occurs C: Character disorder due to the marker significantly occurs

  As shown in Table 5, when the ink of the present invention was used, pencil hardness, fixing property, and marker resistance, which had practically no problem with curability, were obtained. The ink of the present invention was excellent in ejection stability and stability over time.

  As described above, according to the present invention, even when low-energy UV irradiation conditions are used, the curability is good, and even when an ink containing a coloring material such as a pigment is produced, there is practical curing performance and fixability. In addition, it is possible to provide an ink excellent in marker resistance, excellent in ejection stability and stability over time. Further, the above-described embodiments are examples given to show the basic configuration of the present invention, and it goes without saying that, for example, ink having the same performance can be provided even when a dye is used as a coloring material.

DESCRIPTION OF SYMBOLS 1 Ink tank part which accommodates the aqueous | water-based active energy ray curable ink of this invention 2 The head part which an ink tank is attached and actually performs recording 3 The lamp part which performs the ultraviolet irradiation for hardening 4 A head part and a lamp part are driven Drive unit 5 Paper discharge unit for conveying the recording medium to be recorded

Claims (16)

  At least one of water, hydrophilic polymerizable compound 1, hydrophilic polymerizable compound 2 and hydrophilic polymerization initiator, and at least one of the hydrophilic polymerizable compound 1 and hydrophilic polymerizable compound 2 has a polymerizable group. 2 or more, wherein the hydrophilic polymerizable compound 1 is a polymerizable substance having a maleimide group, and the hydrophilic polymerizable compound 2 is a hydrophilic polymerizable substance having an ethylenically unsaturated bond An active energy ray-curable aqueous composition characterized by the above. 2. The active energy ray-curable aqueous composition according to claim 1, wherein the hydrophilic polymerizable compound 1 has one or more sites represented by the following general formula (I).

(Wherein A ₁ is selected from the group consisting of an optionally substituted ethylene oxide chain, an optionally substituted propylene oxide chain and an optionally branched substituted or unsubstituted alkylene group. Or at least one or a combination of two or more thereof.) The active energy ray-curable aqueous composition according to claim 1 or 2, wherein the hydrophilic polymerizable compound 2 has one or more sites represented by the following general formula (II).

(Wherein A ₂ is selected from the group consisting of an optionally substituted ethylene oxide chain, an optionally substituted propylene oxide chain and an optionally branched substituted or unsubstituted alkylene group. And B ₂ represents a moiety represented by the following general formula (III-1) or general formula (III-2).)

(Here, X represents a cyclic linking group having a carbonyl group and a site comprising an unsaturated carbon bond adjacent to the carbonyl group.)

(Here, Y ₁ represents a hydrogen atom, a methyl group, or a halogen atom. D represents any one selected from the following group.)

(R ₂ , R ₃ , R ₄ and R ₅ each independently represents a hydrogen atom, a methyl group or an ethyl group) The active energy ray-curable aqueous composition according to claim 1, wherein the hydrophilic polymerizable compound 2 has at least one site represented by the following general formula (IV).

(Wherein A ₃ is selected from the group consisting of an optionally substituted ethylene oxide chain, an optionally substituted propylene oxide chain and an optionally branched substituted or unsubstituted alkylene group. D ₂ represents an electron donating group, and Y ₂ represents a hydrogen atom, a methyl group, or a halogen atom.)   The active energy ray-curable aqueous composition according to claim 1, wherein at least one of the hydrophilic polymerization initiators is an acyl phosphine oxide compound. The active energy ray-curable aqueous composition according to claim 5, wherein the acylphosphine oxide compound contains one or more compounds represented by the following general formula (V).

(Wherein R ₆ is a lower alkyl group, phenyl group (the phenyl group is unsubstituted or halogen, lower alkyl group, lower alkyloxy group, sulfone group, sulfonic acid group, carboxyl group, hydroxyl group and salts thereof; _{SO 3 -M +, - CO 2} -M +, - O-M +, .R7 lower alkyl group or a phenyl showing a is substituted 1 to 4 times) by any substituent selected from the following atomic groups (E) A group (the phenyl group is unsubstituted or substituted 1 to 4 times by an arbitrary substituent selected from a halogen, a lower alkyl group, and a lower alkyloxy group), and R ₈ is an atom represented by the atomic group (E). Indicates a group.)

(In atomic group E, R ₉ represents — [CH ₂ ] _{X 2} — (X ₂ is 0 or 1) or a substituted or unsubstituted phenylene group, R ₁₀ represents a hydrogen atom, a sulfone group, a carboxyl group, or a hydroxyl group. groups and salts ^{_{thereof;. -SO 3 - M +,}} -CO 2 - M +, -O - M + .m2 representing a is an integer of 0, n2 represents 0 or 1 or each of the M + is independently Represents an equivalent of hydrogen ion, alkali metal ion, alkaline earth metal ion, or ammonium ion represented by HNR ₁₁ R ₁₂ R _{13. In the} ammonium ion, R ₁₁ , R ₁₂ , and R ₁₃ are each independently a hydrogen atom. A lower alkyl group, a monohydroxyl-substituted lower alkyl group or a phenyl group.)   An active energy ray-curable ink comprising at least the active energy ray-curable aqueous composition according to claim 1 and a coloring material.   The active energy ray-curable aqueous composition according to claim 1, which is for inkjet recording.   The active energy ray-curable ink according to claim 7, which is an inkjet recording ink.   An active energy ray-curable aqueous composition according to claim 8 and an inkjet recording ink according to claim 9 are ejected onto a recording medium, and the aqueous composition or the recording medium to which the ink is applied is active. An ink jet recording method comprising a step of irradiating an energy ray to cure the aqueous composition or the ink.   The inkjet recording method according to claim 10, wherein thermal ink is applied to the aqueous composition or the ink to apply the ink onto a recording medium.   A recorded image formed by the ink jet recording method according to claim 10.   An ink cartridge comprising an ink containing portion containing the aqueous composition for ink jet recording according to claim 8 or the ink for ink jet recording according to claim 9.   An ink containing portion containing the inkjet recording aqueous composition according to claim 8 or the inkjet recording ink according to claim 9 and a recording head for discharging the aqueous composition or the ink. A recording unit characterized by the above.   Means for applying the aqueous composition for ink jet recording according to claim 8 or the ink for ink jet recording according to claim 9 to a recording medium, and active energy rays to the ink applied to the recording medium An ink jet recording apparatus comprising a means for irradiating the light. The inkjet according to claim 15, wherein the means for irradiating the active energy ray is an ultraviolet irradiation lamp having a light source having a wavelength of 450 nm or less, and an irradiation intensity of the ultraviolet portion is in a range of 500 to 5,000 mW / cm ^2. Recording device.

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