JP2007314612A - Active energy ray-curable aqueous ink, ink-jet printing method, ink cartridge, printing unit, and ink-jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-miscible active energy ray-curable aqueous ink quickly polymerizable by active energy rays, high in the crosslink degree of its cured product, and also good in the cured product adhesiveness to a printing medium. <P>SOLUTION: The active energy ray-curable aqueous ink essentially comprises water and a polymerizable material, wherein the polymerizable material is a specific water-soluble polymerizable material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an active energy ray-curable aqueous ink containing a novel water-soluble polymerizable compound, an ink jet recording method using the ink, an ink cartridge, a recording unit, and an ink jet recording apparatus.

  Conventionally, a technique using an aqueous paint or ink is known in an ultraviolet curing method in which a cured resin film is formed by curing a resin composition in ink by irradiation with an active energy ray such as ultraviolet rays and image formation is performed. ing. The material composition of the water-based paint or ink used at this time is prepared by using a non-aqueous ultraviolet curable resin composition in an emulsion state in an aqueous solvent. Such an ultraviolet curable resin composition itself is not water-soluble, and until now, in such technology, it has not been realized to make the ultraviolet curable resin itself or the catalyst itself aqueous. Is the current situation.

  Also in the ink jet recording method, ultraviolet curable ink is known. However, the resin composition used in this case is also non-aqueous, and a typical example is a so-called oil-based ink in which a pigment is dispersed in an organic solvent such as toluene or methyl ethyl ketone. In marking applications, an ink containing a monomer, an oligomer and a pigment dispersion is used without using a solvent. These inks are not suitable for precise recording because the viscosity of the ink is not sufficiently low, and are exclusively used for dot recording applications such as marking that do not require precision.

  The oil-based ink used in the ink jet recording as described above does not have ink properties suitable for full-color high-quality recording. In other words, oil-based inks are preferably used with care from the viewpoint of the environment, and solvent-free UV-curable inks can be used only in large-dot low-resolution recording apparatuses. Patent Document 1 discloses an attempt to dissolve an ultraviolet curable resin by using a large amount of vinyl pyrrolidone as a solvent to obtain an ink for ink jet recording. This technology is also intended to be applied to inkjet devices that use thermal energy, but there are practically large restrictions on the materials, such as the use of a large amount of monomers, and it is not very versatile. It cannot be applied. The reason for using the ultraviolet curable ink as described above is as follows.

1) Even if the ink or paint containing a resin dissolved in water is cured, the formed image is insufficient in terms of low water resistance or low gloss.
2) A water-soluble ultraviolet curable resin and a water-soluble polymerization initiator (hereinafter simply referred to as “catalyst”) that has a catalytic function to assist the curing of the resin have been hardly developed. This is the main reason. Furthermore, regarding water-based UV curable ink, as a cause that the material technology itself is difficult to advance,
3) When water is used as a coating solvent, water consumes a large amount of energy for drying compared to an organic solvent, and thus has a practically negative aspect.
It has been pointed out.

  However, it is also true that the ultraviolet curing technology is expected as a curing technology with less energy saving, environmental pollution, and environmental load. Furthermore, the use of the ultraviolet curing method is not limited to image recording in ink jet recording, but pretreatment for imparting recording suitability to the recording medium, and a material for protection and construction is applied to the recording medium on which the image is recorded. It is also useful in post-processing and the like.

U.S. Pat. No. 4,978,969

  Even in application to ink jet recording ink for the purpose of full-color and high-quality recording, the use of aqueous materials such as the above-mentioned aqueous active energy ray-curable resins and catalysts is extremely small. Here, in order to apply to the ink jet system, a material having a low viscosity and good flow characteristics that can correspond to a high density nozzle is required. For example, the amount of the polymerizable compound added in the ink can be increased, the substantial drying time can be shortened, and the cured ink film has excellent physical properties when cured after being applied to the recording medium, Resin materials (catalysts, polymerizable substances) with good co-solubility are required.

  A first example of such a water-soluble active energy ray-curable material is a water-soluble polymerizable compound having both an acidic group and a (meth) acryloyl group or a vinyl group in the molecule. 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 are in practical use. However, since the number of polymerizable functional groups is one per molecule, the polymerization rate is slow, and the degree of cross-linking of the cured product is extremely low, so that the main material of the water-soluble active energy ray-curable material It cannot be.

  The second example is a polymerizable compound that is hydrophilic in water by a polyethylene oxide chain as an industrially produced compound that is soluble in water and has two or more polymerizable functional groups in one molecule. ing. Examples of such include (meth) acrylic acid esters of polyhydric alcohols such as diethylene glycol di (meth) acrylate and tetraethylene glycol di (meth) acrylate. However, according to studies by the present inventors, these groups of compounds may not be water-soluble if the length of the ethylene oxide chain is short. On the other hand, if the ethylene oxide chain is long, water solubility 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 adhesion. .

  JP-A-8-165441 discloses a polyfunctional water-soluble polymerizable compound. The compound disclosed here uses a technique for obtaining water solubility by increasing the number of hydroxyl groups in the molecule in order to impart water solubility. However, according to the study by the present inventors, these 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 less than the level required for ink jet inks. There is a problem that it is a little expensive.

  Japanese Patent Application Laid-Open Nos. 2000-117960 and 2002-187918 disclose (meth) acrylic acid esters of hydrophilic polyepoxides derived from polyalcohols. 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 ink jet inks. However, when a certain color material is used in an ink containing a water-soluble polymerizable compound having a (meth) acrylic acid ester group, there are the following problems. That is, this is a case where an aqueous dye that dissolves in water with an anionic functional group or a pigment dispersion in which a pigment is dispersed in water with an anionic functional group is used as a coloring material. In this case, the pH of the ink is lowered to the acidic region as acrylic acid is generated by hydrolysis of the (meth) acrylic acid ester group. Accordingly, precipitation of the aqueous dye dissolved in the ink and aggregation of the dispersed pigment dispersion may occur, which is problematic in terms of the storage stability of the ink over time. Further, when the recording method is an ink jet recording method in which ink is ejected by the action of thermal energy corresponding to a recording signal, there are the following problems. That is, the water-soluble polymerizable compound in the ink undergoes thermal polymerization due to thermal energy, and a water-insoluble polymer is generated in the nozzle, which may cause problems in ink ejection.

  Accordingly, a first object of the present invention is to provide an active energy ray-curable water-based ink (hereinafter simply referred to as “a”) that is rapidly polymerized by active energy rays and has a high degree of crosslinking of the cured product and excellent adhesion to a recording medium. In some cases, it is referred to as “ink”.

  The second object of the present invention is to provide an ink that achieves the above first object, the viscosity of which satisfies the low viscosity level required for inkjet, and is excellent in storage stability over time. It is in.

  A third object of the present invention is an ink that achieves the above first and second objects, and can be used in an ink jet recording system in which the recording method ejects ink by the action of thermal energy corresponding to a recording signal. To provide ink. That is, an object of the present invention is to provide an ink excellent in ejection stability that causes thermal polymerization by thermal energy and does not affect ink ejection.

  Another object of the present invention is to provide an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus using the above ink.

（一般式（Ｉ）中、Ｚはテトラカルボン酸の残基を示す。３個の内、少なくとも２個のＹは下記一般式（II）を示し、又、０乃至２個のＹは−ＯＭを示す。Ｍはそれぞれ独立に、水素原子、又はアルカリ金属を示す。

（一般式（II）中、Ａは、置換又は未置換のエチレンオキシド鎖、置換又は未置換のプロピレンオキシド鎖、及び置換又は未置換のアルキレン基からなる群から選ばれる少なくとも１つを示す。Ｘは水素原子又はメチル基を示す。但し、一般式（Ｉ）中のエチレンオキシド鎖及びプロピレンオキシド鎖の合計は１乃至１５個である。）） The above object is achieved by the present invention described below. That is, the present invention provides an ink characterized in that, in an ink containing at least water and a polymerizable substance, the polymerizable substance is a water-soluble polymerizable substance represented by the following general formula (I).

(In the general formula (I), Z represents a tetracarboxylic acid residue. Of the three, at least two Y represent the following general formula (II), and 0 to 2 Y represent —OM. Each M independently represents a hydrogen atom or an alkali metal.

(In General Formula (II), A represents at least one selected from the group consisting of a substituted or unsubstituted ethylene oxide chain, a substituted or unsubstituted propylene oxide chain, and a substituted or unsubstituted alkylene group. X represents A hydrogen atom or a methyl group, provided that the total number of ethylene oxide chains and propylene oxide chains in general formula (I) is 1 to 15))

  The present invention also includes a step of applying the ink to a recording medium, and a step of irradiating the recording medium to which the aqueous ink has been applied with active energy rays to cure the aqueous ink. Provide a method. The present invention also provides an ink cartridge comprising an ink containing portion for containing the ink. According to another aspect of the present invention, there is provided a recording unit comprising an ink storage portion for storing the ink and a recording head for discharging the ink. The present invention also provides an ink jet recording apparatus comprising means for irradiating the aqueous ink applied to a recording medium with active energy rays.

  According to the present invention, it is possible to provide an active energy ray-curable ink that is rapidly polymerized by active energy rays and has a high degree of cross-linking of the formed cured product and excellent adhesion to a recording medium. Further, it is possible to provide an ink that satisfies the low viscosity level required for inkjet and has excellent storage stability with time. Further, it is possible to provide an ink that can be used in an ink jet recording method in which the recording method ejects ink by the action of thermal energy corresponding to a recording signal. That is, it is possible to provide an ink having excellent ejection stability that causes thermal polymerization by thermal energy and does not affect the ejection of the ink. Furthermore, an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus using the ink can be provided.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In view of the above-described object, the present inventors have made various studies. In the process, an ink having the above composition and containing a water-soluble polymerization initiator that generates radicals by the action of active energy rays was prepared, and the ink was evaluated. As a result, the ink having such a configuration has been found to be excellent in curing performance (cured degree of the formed cured product), pH stability, and heat-resistant polymerization property, and has led to the present invention.

  The reason why such a result is obtained is not clear, but is considered as follows. The water-soluble polymerizable substance having an acrylamide structure represented by the general formula (I) used in the present invention is less susceptible to hydrolysis than the water-soluble polymerizable substance having an acrylic ester structure. As a result, since the amount of acrylic acid produced by hydrolysis that causes a change in pH is small, it is considered that the pH stability when the ink is prepared is excellent.

  Moreover, it is thought that the reason for being excellent in heat-resistant polymerizability is either of the following. This is because water-soluble polymerizable substances having an acrylamide structure are more resistant to thermal polymerization than those having an acrylic ester structure, or the amount of acrylic acid produced by hydrolysis is small, and acrylic acid itself is thermally polymerized. It is thought that this is because

  The operation and effect of the water-based inkjet method, which is a main application example of the ink of the present invention, will be described below. The active energy rays used in the present invention can be ultraviolet rays, electron beams, or the like. Hereinafter, description will be given by taking inks that are radically polymerized and cured by ultraviolet rays that are particularly preferably used as representative examples. Of course, the active energy ray used for curing in the present invention is not limited to ultraviolet rays.

The main purpose of using the ink of the present invention as the water-based ink used in the inkjet recording method is, for example, in the following points.
1) It is possible to cope with an improvement in recording speed by increasing the drying property of the ink.
2) By allowing the water-soluble polymerizable substance to act as a binder for the color material and applying the color material to the recording medium, it is possible to form an image having excellent scratch resistance on various papers.
3) Light scattering from the color material is reduced, and a transparent ink layer can be formed.
4) As a result, it is possible to expand the color reproduction range of the process color, give the ink an image forming ability with high density, and excellent chroma and lightness.
5) Further, it is possible to protect the color material from active light, gas components in the air, moisture, and the like.

  The use of 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 pigment color and scratch resistance. Demonstrate. Furthermore, the use of the ink of the present invention enables recording with a water-based ink on a non-absorbent recording medium.

  The active energy ray curing method is one of forced drying methods. Before the ink applied to a recording medium such as paper completely penetrates into the recording medium, that is, within the time when the ink forms a free surface. It can be said that this is a method of freezing the state. In the ink of the present invention, the permeation and evaporation of an aqueous solvent such as water gradually proceeds slowly from the solidified ink layer. However, as described above, apparent drying occurs quickly, so that the fixing time in the sense that paper conveyance, stacking, and the like are possible can be handled as being shortened. However, as long as an aqueous solvent is used, it is inevitable that true drying is slower than ink using an organic solvent. However, when using the ink of the present invention, a final forced heat dryer may be provided depending on the application.

  As in the case of the ink of the present invention, how water-soluble polymerizable substances that undergo radical polymerization by active energy rays proceed in the presence of moisture is purely important as a problem of radical reaction rate. is there. According to the study by the present inventors, it has been observed that a colorless ink that does not contain a coloring material has a particularly slow reaction with water-based polymerizable substances in water compared to a solventless system. Absent. Of course, since the polymer contains water, the solid physical properties of the cured product are different from those of the solventless system.

Next, each constituent material of the ink of the present invention having the above-described excellent actions and effects will be described.
(Water-soluble polymerizable substance)
The water-soluble polymerizable substance used in the present invention is characterized by being represented by the following general formula (I).

（一般式（Ｉ）中、Ｚはテトラカルボン酸の残基を示す。３個の内、少なくとも２個のＹは下記一般式（II）を示し、又、０乃至２個のＹは−ＯＭを示す。Ｍはそれぞれ独立に、水素原子、又はアルカリ金属を示す。

（一般式（II）中、Ａは、置換又は未置換のエチレンオキシド鎖、置換又は未置換のプロピレンオキシド鎖、及び置換又は未置換のアルキレン基からなる群から選ばれる少なくとも１つを示す。Ｘは水素原子又はメチル基を示す。但し、一般式（Ｉ）中のエチレンオキシド鎖及びプロピレンオキシド鎖の合計は１乃至１５個である。））

(In the general formula (I), Z represents a tetracarboxylic acid residue. Of the three, at least two Y represent the following general formula (II), and 0 to 2 Y represent —OM. Each M independently represents a hydrogen atom or an alkali metal.

(In General Formula (II), A represents at least one selected from the group consisting of a substituted or unsubstituted ethylene oxide chain, a substituted or unsubstituted propylene oxide chain, and a substituted or unsubstituted alkylene group. X represents A hydrogen atom or a methyl group, provided that the total number of ethylene oxide chains and propylene oxide chains in general formula (I) is 1 to 15))

  In the present invention, the number of polymerization functional groups of the water-soluble polymerizable substance is preferably in the range of 2 to 3 from the viewpoints of ink curing performance and low viscosity. The curing performance improves as the number of polymerized functional groups in the water-soluble polymerizable substance increases. However, as the number of functional groups increases, the viscosity of the ink increases, and it becomes difficult to obtain an ink with good flow characteristics corresponding to an ink jet type high-density nozzle. On the other hand, if the functional group of the water-soluble polymerizable substance is 1, the polymerization rate is low and the degree of crosslinking of the cured product is extremely low, so that it is not suitable for the ink material of the present invention.

  The water-soluble polymerizable substance used in the present invention is imparted with hydrophilicity by an ethylene oxide chain and / or a propylene oxide chain, etc. included in the general formula (I). The total of the ethylene oxide chain and the propylene oxide chain in the general formula (I) is preferably in the range of 1 to 15, more preferably 1 to 5, and particularly preferably 2 to 3. If there are few ethylene oxide chains or propylene oxide chains in the water-soluble polymerizable substance, water solubility may not be obtained. On the other hand, when there are many ethylene oxide chains or propylene oxide chains, water solubility is obtained, but the solid physical properties of the cured product when polymerized or cured may be insufficient in performance such as hardness and adhesion. Here, the number of ethylene oxide chains and propylene oxide chains in the general formula (I) has a distribution, and is obtained as an average value. In the present invention, the above average value is defined as the total of the ethylene oxide chain and the propylene oxide chain.

Specific examples of the alkylene group in the general formula (II) include a methylene group, an ethylene group, a propylene group, and a butylene group. Of course, these alkylene groups may have a side chain or may have a substituent. Specific examples of the substituent include a hydroxyl group and an amino group. Further, the ethylene oxide chain and the propylene oxide chain in the general formula (II) are specifically represented by the following structural formula.

  In the general formula (I), examples of the tetracarboxylic acid residue represented by Z include the following. Examples include aromatic rings such as benzene rings, chain aliphatic compounds having 4 or more carbon atoms such as butanetetracarboxylic acid and ethylenediaminetetraacetic acid, and alicyclic compounds such as cyclohexane rings. The tetracarboxylic acid residue used in the present invention is not limited to these.

  Specific examples of the water-soluble polymerizable substance represented by the general formula (I) include water-soluble polymerizable substances having the structure shown below. However, the water-soluble polymerizable substance used in the present invention is not limited to these. These compounds have high hydrophilicity, are water-soluble, have polymerizability, have a high polymerization rate, and themselves have a low viscosity. At the same time, the viscosity of the aqueous solution is much lower than that of conventionally known compounds. In the present invention, two or more water-soluble polymerizable substances can be used in combination.

  The water-soluble polymerizable substance represented by the general formula (I) of the present invention is produced by the following method. For example, the exemplified compound 3 in the general formula (I) is obtained by condensing pyromellitic acid or pyromellitic anhydride to one amino group of ethylenediamine, and then condensing acrylic acid or acrylic acid chloride to the other amino group. Is obtained. The exemplified compound 3 can also be obtained by condensing acrylic acid or acrylic acid chloride to one amino group of ethylenediamine and then condensing the other amino group to pyromellitic acid or pyromellitic acid anhydride.

Moreover, the ethylene oxide or propylene oxide unit of (A) in the general formula (II) converts a diamine into an amino alcohol derivative. Thereafter, an addition reaction of ethylene oxide or propylene oxide is performed on the hydroxyl group, and an arbitrary equivalent number of ethylene oxide chains or propylene oxide chains are added. Then, it is obtained by performing a dehydration condensation reaction with the addition compound and C _{1 to} C ₄ alkanolacrylamide. Moreover, the compound which has a secondary alcohol group performs the addition reaction of epichlorohydrin to the hydroxyl group of an amino alcohol derivative, and adds a glycidyl group. Then, the addition compound is obtained by reacting ammonia to introduce an amino group, and then condensing acrylic acid or acrylic acid chloride.

  The group having an anionic group in the general formula (I) can be obtained by making at least one of the carboxyl groups of the tetracarboxylic acid an anionic group.

  The group having an anionic group in the general formula (I) has one of a carboxyl group or a sulfonic acid group, a phenoxy group, a phosphoric acid group, or a salt thereof. Further, it can be obtained by reacting a compound having a group capable of binding to an OH group with the above polyol, reacting with the above glycidyl group, or adding Michael to one acrylamide-bonded group.

（上記一般式（III）中、Ｒ₂はアルキル基、フェニル基（未置換、又はハロゲン、アルキル基、アルキルオキシ基、スルホン酸基（−ＳＯ₃Ｍ）、カルボキシル基（−ＣＯ₂Ｍ）、ヒドロキシル基（−ＯＭ）及びそれらの塩、又は下記一般式（IV）の原子団から選ばれる任意の置換基により１乃至４回置換されている。）を表す。 (Water-soluble polymerization initiator)
The water-soluble polymerization initiator used in the present invention is preferably at least one substance selected from the following general formulas (III), (V) to (VIII).

(In the general formula (III), R ₂ is an alkyl group, a phenyl group (unsubstituted or halogen, an alkyl group, an alkyloxy group, a sulfonic acid group (—SO ₃ M), a carboxyl group (—CO ₂ M), A hydroxyl group (—OM) and a salt thereof, or an arbitrary substituent selected from an atomic group represented by the following general formula (IV).

（上記一般式（IV）中、Ｒ₅は、−［ＣＨ₂］_x2−（ｘ２は０又は１）、又は置換若しくは未置換のフェニレン基を表す。Ｒ₆は水素原子、スルホン酸基（−ＳＯ₃Ｍ）、カルボキシル基（−ＣＯ₂Ｍ）、又はヒドロキシル基（−ＯＭ）を表す。ｍ２は０乃至１０の整数、ｎ２は０又は１を表す。Ｒ₃はアルキルオキシ基又はフェニル基（未置換、又はハロゲン、アルキル基、アルキルオキシ基から選ばれる任意の置換基により１乃至４回置換されている。）を表す。Ｒ₄は前記一般式（Ｖ）で示される原子団を表す。Ｍはそれぞれ独立に、水素イオン、アルカリ金属イオン、アルカリ土類金属イオンの当量、又はＨＮＲ₇Ｒ₈Ｒ₉で表されるアンモニウムイオン（Ｒ₇、Ｒ₈、Ｒ₉はそれぞれ独立に、水素原子、アルキル基、モノヒドロキシル置換アルキル基、又はフェニル基を意味する。）を表す。）

(In the general formula (IV), R ₅ represents — [CH ₂ ] _x2 — (x2 is 0 or 1) or a substituted or unsubstituted phenylene group. R ₆ represents a hydrogen atom, a sulfonic acid group (— SO ₃ M), a carboxyl group (—CO ₂ M), or a hydroxyl group (—OM), m2 represents an integer of 0 to 10, n2 represents 0 or 1. R ₃ represents an alkyloxy group or a phenyl group ( R ₄ represents an atomic group represented by the general formula (V), which is unsubstituted or substituted 1 to 4 times by an arbitrary substituent selected from a halogen, an alkyl group, and an alkyloxy group. M is independently hydrogen ion, alkali metal ion, equivalent of alkaline earth metal ion, or ammonium ion represented by HNR ₇ R ₈ R ₉ (R ₇ , R ₈ , R ₉ are each independently hydrogen atom , Alkyl group, monohydroxyl Conversion alkyl group, or means a phenyl group.) Represents a.)

（一般式（Ｖ）中、ｍ３は１以上の整数であり、ｎ３は０以上の整数であり、ｍ３＋ｎ３は１乃至８の整数である。）

(In general formula (V), m3 is an integer of 1 or more, n3 is an integer of 0 or more, and m3 + n3 is an integer of 1 to 8.)

（一般式（VI）中、Ｒ₁₀及びＲ₁₁はそれぞれ独立に、水素原子、又は置換若しくは未置換のアルキル基であり、ｍ４は５乃至１０の整数である。）

(In General Formula (VI), R ₁₀ and R ₁₁ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group, and m4 is an integer of 5 to 10.)

（一般式（VII）中、Ｒ₁₀及びＲ₁₁はそれぞれ独立に、水素原子、又は置換若しくは未置換のアルキル基であり、Ｒ₁₂は、−（ＣＨ₂）_x−（ｘは０又は１）、−Ｏ−（ＣＨ₂）_y−（ｙは１又は２）又は置換若しくは未置換のフェニレン基であり、Ｍは水素原子又はアルカリ金属である。）

(In General Formula (VII), R ₁₀ and R ₁₁ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₁₂ is — (CH ₂ ) _x — (x is 0 or 1). , —O— (CH ₂ ) _y — (y is 1 or 2) or a substituted or unsubstituted phenylene group, and M is a hydrogen atom or an alkali metal.

（一般式（VIII）中、Ｒ₁₀及びＲ₁₁はそれぞれ独立に、水素原子、又は置換若しくは未置換のアルキル基であり、Ｍは水素原子又はアルカリ金属である。）

(In general formula (VIII), R ₁₀ and R ₁₁ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group, and M is a hydrogen atom or an alkali metal.)

In general formulas (III) to (VIII), the alkyl group is preferably a linear or branched lower alkyl group, and specific examples include a methyl group, an ethyl group, a propyl group, and a butyl group. It is done. The alkyloxy group is preferably a linear or branched lower alkyloxy group, and specific examples include lower alkyloxy groups such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. M is an alkali metal ion, an equivalent of an alkaline earth metal ion, or an ammonium ion represented by HNR ₇ R ₈ R ₉ . Specific examples of the alkali metal ion include ions such as lithium, sodium and potassium. Specific examples of alkaline earth metal ions include ions of calcium, strontium, barium and the like. Specific examples of the ammonium ion represented by HNR ₇ R ₈ R ₉ include ions such as ammonium, dimethylethanolammonium, methyldiethanolammonium, triethanolammonium, and anilinium. Of course, the present invention is not limited to these.

  Specific examples of these water-soluble polymerization initiators include, for example, water-soluble polymerizable substances having the structure shown below, but the water-soluble polymerization initiator used in the present invention is not limited thereto.

  In the present invention, when a thioxanthone-based water-soluble polymerization initiator or the like is used as the water-soluble polymerization initiator, it is preferable to add a hydrogen donor. Examples of the hydrogen donor that can be used in the present invention include triethanolamine.

  In the present invention, two or more water-soluble polymerization initiators can be used in combination. By adding two or more types of water-soluble polymerization initiators, generation of further radicals can be expected using light having a wavelength that cannot be effectively used with one type of water-soluble polymerization initiator. Further, the water-soluble polymerization initiator as described above is not necessarily used when an electron beam curing method in which an ink is cured using an electron beam as an active energy ray.

(Pigment dispersion)
The ink of the present invention can be used as a colored ink that is cured by irradiation with an active energy ray or an active energy ray-curable coating material by containing a pigment as a coloring material. At this time, it is preferable to use a pigment dispersion in which a pigment is uniformly dispersed in an aqueous medium as a coloring material. As the pigment dispersion, it is particularly preferable to use a pigment dispersion in which the pigment is stably dispersed in water with an anionic functional group. For example, water-based gravure inks, pigment dispersions for aqueous writing instruments, and pigment dispersions for conventionally known inkjet inks that are stable in nonionic or anionic systems can be applied as they are.

  Pigment dispersions having an anionic dissociation group and dispersed using an alkali-soluble water-soluble polymer are disclosed, for example, in JP-A Nos. 5-247392 and 8-143802. A pigment dispersion dispersed with a surfactant having an anionic dissociation group is disclosed in JP-A-8-209048. A pigment dispersion encapsulated with a polymer and dispersed by imparting an anionic dissociation group to its surface is described in the following document. The documents are JP-A-10-140065, JP-A-9-316353, JP-A-9-151342, JP-A-9-104834, and JP-A-9-031360. Further, a pigment dispersion in which a pigment is dispersed by bonding an anionic dissociation group to the pigment surface by a chemical reaction is described in the following document. The references are US Pat. No. 5,837,045 and US Pat. No. 5,851,280. In the ink of the present invention, any of the various pigment dispersions described above can be used as the ink coloring material.

  When a pigment is used as the coloring material of the ink of the present invention, it is preferable to use a pigment dispersion in which the pigment is dispersed in the form of fine particles. In particular, the basic elements of a pigment dispersion that can be suitably used for ink are as follows. That is, the pigment is dispersed in an aqueous medium, and the particle size distribution as a dispersion is in the range of 25 nm to 350 nm in terms of average particle diameter. The viscosity of the ink containing the pigment can be adjusted to a range that does not affect ejection. Furthermore, it is preferable to satisfy the aforementioned compatibility with the water-soluble polymerizable substance of the present invention, which is essential for making the ink curable with active energy rays. 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 used as appropriate when indicated by the color index (CI) number.
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.
In addition, C.I. I. Pigment Orange: 16, 36, 43, 51, 55, 59, 61, 71.
In addition, C.I. 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.
In addition, C.I. I. Pigment violet: 19, 23, 29, 30, 37, 40, 50.
In addition, C.I. I. Pigment Blue: 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64.
In addition, C.I. I. Pigment green: 7, 36.
In addition, C.I. I. Pigment brown: 23, 25, 26, and the like.

<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 recorded material, it is sufficiently smaller than the wavelength of visible light, so that a recorded material that can be said to be sufficiently transparent can be obtained if the scattering is small.

<Dye>
The ink of the present invention is not limited to the above-described pigment, but may be an ink having a mode in which a dye is used as a coloring material and a water-soluble dye is contained in a dissolved state. The dye can be used as long as fading due to irradiation with active energy rays does not cause a practical problem. Further, a color material dispersion containing a disperse dye, an oil-soluble dye or the like in a dispersed state can also be applied in the same manner as the above-described pigment dispersion. These are appropriately selected according to the application.

  For example, in the case of the ink of the present invention, it is preferable that after the ink is applied to a recording medium (paper or the like), the active energy ray-curable polymer substance in the ink is polymerized and cured by the active energy rays. As described above, when a dye is used as a coloring material, unlike the case of using the above-described pigment, it cannot be used without any fading due to active energy ray irradiation, and is somewhat accompanied by fading. For this reason, when a dye is applied as the colorant of the ink, it is preferable to use a so-called azo metal-containing dye, which forms a complex with metal ions, because there is little fading due to light. However, if the level of fading is not a problem, even a general water-soluble dye can be used at least as an ink. On the premise of this, dyes applicable in the sense of having a hue of black or process color are the following compounds.

Examples of the dye having a black hue include monoazo complexes, disazo complexes, and non-complex azo black dyes coordinated with a polyvalent metal such as Cr, Cu, Mn, Al, Zn, and Fe. Is mentioned. C. I. Direct black: 7, 19, 51, 154, 174, 195 and the like can be suitably used.
In addition, the dyes used in other color inks can be appropriately selected from those listed below when indicated by the color index (CI) number.
C. I. Acid yellow: 11, 17, 23, 25, 29, 42, 49, 61, 71.
In addition, C.I. I. Direct yellow: 12, 24, 26, 44, 86, 87, 98, 100, 130, 132, 142.
In addition, C.I. I. Acid Red: 1, 6, 8, 32, 35, 37, 51, 52, 80, 85, 87, 92, 94, 115, 180, 254, 256, 289, 315, 317.
In addition, C.I. I. Direct red: 1, 4, 13, 17, 23, 28, 31, 62, 79, 81, 83, 89, 227, 240, 242, 243.
In addition, C.I. I. Acid Blue: 9, 22, 40, 59, 93, 102, 104, 113, 117, 120, 167, 229, 234, 254.
In addition, C.I. I. Direct blue: 6, 22, 25, 71, 78, 86, 90, 106, 199 and the like.
The dye content (% by mass) in the ink is preferably 0.1% by mass or more and 10% by mass or less based on the total mass of the ink. When the content of the dye is low, for example, it is preferably applied to a so-called light ink of density-modulated ink.

<Prescription for clear ink>
The ink of the present invention can be made a clear ink by containing a transparent water-based ink without containing the colorant as described above. In particular, when prepared so as to have ink jet recording characteristics, a clear ink as an active energy ray-curable aqueous ink can be obtained. If such an ink is used, a clear film can be obtained because it does not contain a color material. The use of clear inks that do not contain color materials can be used for undercoats to give recording media suitability for image recording, or to protect the surface of images formed with ordinary inks, and to give decoration and gloss For example, it can be used as an overcoat for the purpose. In the clear ink, colorless pigments and fine particles that are not intended for coloring can be dispersed and contained depending on applications such as oxidation prevention and fading prevention. By adding these, it is possible to improve various characteristics such as image quality, fastness and workability (handling property) of the recorded matter in both the undercoat and the overcoat.

  Prescription conditions for such a clear ink are as follows. The content (% by mass) of the water-soluble polymerizable substance is preferably 10% by mass or more and 70% by mass or less based on the total mass of the ink. Moreover, it is preferable that a water-soluble polymerization initiator (for example, active energy ray polymerization catalyst) shall be 1 to 10 mass parts with respect to 100 mass parts of said water-soluble polymerizable substances. At the same time, the content (% by mass) of the water-soluble polymerization initiator is preferably 0.5% by mass or more based on the total mass of the ink. The content (% by mass) of water and / or water-soluble organic solvent is preferably 40% by mass to 90% by mass, and more preferably 60% by mass to 75% by mass, based on the total mass of the ink. .

<Reactive diluent>
As described above, when the ink of the present invention is used as a clear ink, an aqueous 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, thus reducing the effect on solid physical properties. is there. Examples of the reactive diluent selected for such purposes include the following. Examples thereof include acryloylmorpholine, N-vinylpyrrolidone, acrylamide, methylenebisacrylamide, monosaccharide monoacrylate, oligoethylene oxide monoacrylate, and dibasic acid monoacrylate.

<Solvent component>
Further, when the ink of the present invention is used as a clear ink, it is preferable not to use a solvent that imparts moisture retention, which has been conventionally used for water-based inkjet inks. This is because the clear ink does not contain a solid component such as a pigment, so that the viscosity is small and can be easily recovered even if there is a slight viscosity increase. Of course, it is permissible to add more highly moisturizing solvents as described below. These can be selected from a large number of compounds conventionally used in aqueous inkjet.

  When the ink of 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 recording medium. In the case of recording on a non-absorbable recording medium, the solvent component is not included in the ink, but only water is contained, and all of the polymerizable substance component is cured and solidified. preferable.

  When the solvent component is added to the ink in an amount of 10% by mass or more, it is preferable that the recording medium on which the image is formed has a certain absorbency in terms of the strength of the finally obtained ink film. For example, in the case of recording with a water-based gravure ink, a recording medium imparted with constant wettability and permeability is used and forced drying is performed. Similarly, in the ink of the present invention, when the solvent component is added to the ink in an amount of 10% by mass or more, a pretreatment for imparting water-based ink acceptability to the recording medium is performed and the ink is activated. It is preferable to perform natural or forced drying treatment after the energy ray curing. Since various water-soluble polymerizable substances disclosed in the present invention have a certain moisture retention (water evaporation suppression, water absorption), it is also possible to have an ink configuration in which the solvent is completely eliminated. . In this case, in order to ensure the reliability of the recording apparatus at a practical level, measures such as capping, ink suction at the start of recording, and idle ejection may be taken.

  Listed below are water-soluble organic solvents that can be used in the water-based ink of the present invention and can be evaporated and dried relatively easily. In the ink of the present invention, a solvent arbitrarily selected from these water-soluble organic solvents can be added. Examples thereof include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, and ethylene glycol monoallyl ether. Moreover, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and triethylene glycol monomethyl ether are listed. In addition, glycol ethers such as triethylene glycol monoethyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether, and monohydric alcohols can be used.

<Material structure in ink containing colorant>
When the ink of the present invention is used as an ink containing a coloring material, it is preferable to adjust the contents of the catalyst and the water-soluble polymerizable substance in the ink according to the absorption characteristics of the containing coloring material. As described above, the content of water and / or water-soluble organic solvent is 40% by mass to 90% by mass based on the total mass of the ink, and further 60% by mass to 75% by mass. The following is preferable. Furthermore, the content (% by mass) of the water-soluble polymerizable substance in the ink is preferably 1% by mass to 35% by mass, and more preferably 10% by mass to 25% by mass based on the total mass of the ink. The water-soluble polymerization initiator depends on the content of the water-soluble polymerizable substance, but is generally 0.1% by mass or more and 7% by mass or less, more preferably 0.3% by mass or more and 5% by mass based on the total mass of the ink. The following is preferable.

  When a pigment is used as the ink coloring material, the content (% by mass) of the pure pigment in the ink is generally 0.3% by mass or more and 10% by mass or less based on the total mass of the ink. preferable. The coloring power of the pigment depends on the dispersion state of the pigment particles. However, when the content of the pure pigment is 0.3% by mass or more and 1% by mass or less based on the total mass of the ink, the range used as a light ink. It becomes. Further, when it is more than that, that is, more than 1% by mass and 10% by mass or less, a concentration used for general color coloring is given. The concentration of the pigment dispersion also depends on the viscosity and flow characteristics required by the recording apparatus.

  Regarding the viscosity of the ink, when applied to an on-demand type ink jet recording apparatus, the upper limit of the viscosity at 25 ° C. is preferably 15 mPa · s. In addition, when applied to an ink jet recording apparatus having high density and high driving frequency nozzles, the upper limit of the viscosity at 25 ° C. is preferably 10 mPa · s.

  The surface tension is preferably 35 mN / m (dyne / cm) or more at 25 ° C. in view of recording on a recording medium such as plain paper using the ink of the present invention. In recording on plain paper, it is preferable to sufficiently suppress bleeding between colors. For this purpose, in ordinary inkjet inks, it is necessary to adjust the surface tension to a low value of about 30 mN / m and allow the ink to penetrate into the recording medium within a short time. However, this case is accompanied by a decrease in image density.

  On the other hand, in the ink of the present invention, it is preferable to set the surface tension as high as possible so that the ink stays on the surface of the recording medium as much as possible when the active energy is irradiated. By doing so, the ink is effectively cured in the vicinity of the surface of the recording medium, bleeding can be sufficiently suppressed, and at the same time, a high image density can be obtained. In order to ensure this image density, on the other hand, it is preferable that the ink is wetted to the recording medium to some extent at the time of active energy irradiation, so the upper limit of the surface tension is about 50 mN / m at 25 ° C. More preferred.

<< Inkjet recording method >>
Next, an ink jet recording method in which the ink as described above is applied to a recording medium by an ink jet recording method and then cured by irradiation with an active energy ray will be described.

<Recording device>
The ink of the present invention is suitably used for an ink jet recording type head. It is also effective as an ink storage container for storing the ink or as an ink for filling the ink. In particular, the present invention provides an excellent effect in a recording apparatus having a bubble jet (registered trademark) recording head among inkjet 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 particular, in the case of the on-demand type, the electrothermal transducer disposed corresponding to the sheet or liquid path holding the ink is subjected to a rapid temperature rise corresponding to the recorded information and exceeding the nucleate boiling. At least one drive signal is applied. In this way, heat energy is generated in the electrothermal transducer, causing film boiling on the heat acting surface of the recording head, resulting in a one-to-one correspondence with this drive signal and forming bubbles in the ink. It is effective because it is possible. By the growth and contraction of the bubbles, ink is ejected through the ejection opening 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 the drive signal in the form of a pulse, those described in US Pat. No. 4,463,359 and US Pat. No. 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.

  The configuration of the recording head includes a combination of a discharge port, a liquid path, and an electrothermal transducer (linear liquid flow path or right-angle liquid flow path) as disclosed in the above specifications, It is preferable to have a configuration in which the region is bent. These configurations are described in US Pat. No. 4,558,333 and US Pat. No. 4,459,600. Alternatively, the present invention is also effective for an air communication type discharge method described in Japanese Patent No. 29682880, Japanese Patent No. 3246949, and Japanese Patent Application Laid-Open No. 11-188870. In addition, the present invention is also effective for a configuration (JP-A-59-123670, etc.) in which a common discharge port is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters. .

  Further, a full-line type recording head having a length corresponding to the maximum recording medium width that can be recorded by the recording apparatus can be used as follows. For example, a configuration satisfying the length by a combination of a plurality of recording heads as disclosed in the above specification or a configuration as a single recording head formed integrally may be used. The present invention can exhibit the above-described effects more effectively in any of the configurations as described above.

  In addition, it is provided integrally with a replaceable chip-type recording head that enables electrical connection to the recording apparatus and supply of ink from the recording apparatus, or the recording head itself, by attaching it to the recording apparatus. The present invention is also effective when a cartridge type recording head is used.

  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. . Specifically, capping means for the recording head, cleaning means, pressurization or suction means, electrothermal converter or preheating means using a heating element different from this, or a combination thereof, and recording This is a preliminary discharge mode in which another discharge is performed.

  A specific example of a recording apparatus for carrying out the recording method of the present invention has a configuration as shown in the schematic diagram of the front side of the recording apparatus in FIG. For example, an ink cartridge unit 1 that contains the ink of the present invention, a head unit 2 that performs recording, a lamp unit 3 that performs ultraviolet irradiation for curing, a driving unit 4 that drives the head unit and the lamp unit, and a recording medium to be recorded Is a recording apparatus provided with a paper discharge unit 5 that conveys. 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, a nozzle unit for ejecting ink is arranged symmetrically for each color in a head unit 2, and the head unit 2 and the lamp unit 3 are integrally scanned left and right to apply ink to a recording medium. After that, irradiation with active energy is performed immediately. Details of the ultraviolet lamp preferably used as the active energy will be described later. Therefore, when this recording apparatus is used, an ink jet recording method capable of suppressing bleeding of ink and bleeding between colors on a recording medium such as paper can be obtained, and a high-quality and high-definition image formation can be realized. .

  In the ink cartridge unit 1, four colors of black (Bk), cyan (C), magenta (M), and yellow (Y) are arranged here. In order to record a higher-definition image, six colors of light cyan (LC) and light magenta (LM) may be arranged. Further, since the reactivity of black is inferior to that of other colors, a three-color arrangement for forming process black combining cyan, magenta, and yellow may be used. In the present invention, it is preferable to use an ink cartridge that can block light.

  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 feed / discharge is performed by wrapping 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 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 Pa to 10 Pa during lighting. The emission spectrum of these mercury lamps in the ultraviolet region is in the range of 184 nm to 450 nm, which is suitable for efficiently reacting a water-soluble polymerizable substance in black or colored ink. In addition, a small power supply can be used for mounting the power supply in the recording apparatus, which is also suitable in that sense. As the mercury lamp, for example, a metal halide lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon flash lamp, a deep ultraviolet lamp, a lamp that uses a microwave to excite the mercury lamp from the outside without using an electrode, an ultraviolet laser, and the like are in practical use. Since the emission wavelength region of these lamps includes the above range, it is basically applicable if the power source size, input intensity, lamp shape, etc. are allowed. The light source is selected in accordance with the sensitivity of the water-soluble polymerization initiator used.

UV intensity that may be used to cure the ink of the present invention, in the wavelength region effective for curing is preferably 500 mW / cm ² or more 5,000 MW / cm ² or less. If the irradiation intensity is weak, the effects of the present invention may not be sufficiently obtained. On the other hand, if the irradiation intensity is too strong, the recording medium 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 as long as the gist thereof is not exceeded. In the text, “part” and “%” are based on mass unless otherwise specified.

<Examples 1 to 8>
The components described in Table 1 below were mixed and dissolved or dispersed by thorough stirring, followed by pressure filtration with a filter having a pore size of 0.50 μm to prepare inks of Examples 1 to 8, respectively. The pH of the ink was adjusted using a 0.2N aqueous sodium hydroxide solution so that the pH was finally 8.5.

<Comparative Examples 1 and 2>
The components described in Table 1 below were mixed and dissolved or dispersed by thorough stirring, followed by pressure filtration with a filter having a pore size of 0.50 μm to prepare inks of Comparative Examples 1 and 2. The pH of the ink was adjusted using a 0.2N aqueous sodium hydroxide solution so that the pH was finally 8.5. Moreover, the following exemplary compounds 9 and 10 were used for the water-soluble polymerizable substance used in the comparative example.

<Evaluation of ink>
The inks of Examples 1 to 8 and Comparative Examples 1 and 2 of the present invention obtained above were loaded into an ink jet recording apparatus. The recording apparatus is an ink jet recording apparatus that ejects ink by the action of thermal energy according to a recording signal. Specifically, the inkjet recording device PIXUS550i (manufactured by Canon) is equipped with a UV lamp that excites a mercury lamp from the outside using a microwave in the form adjacent to the recording head portion as shown in FIG. What was done was used. The UV lamp used a D bulb. The intensity at the irradiation position is 1,500 mW / cm ² . Using the modified machine, the following items (1), (2), and (3) were evaluated according to the following methods and standards. Table 2 summarizes the evaluation results obtained using the inks of Examples 1 to 8 and Comparative Examples 1 and 2.

(1) Ink curing performance Using the modified machine, a 12-point character pattern was recorded on PPC paper (manufactured by Canon) with a predetermined ink. The following evaluation was performed on the obtained recorded matter. The evaluation of the clear ink in Example 1 was made with 12-point characters for ink containing only a normal solvent system that is not an active energy ray curing system and a color material immediately before recording with the clear ink (within 0.1 second). The pattern was recorded. Then, a 12-point character pattern of clear ink was recorded in an overcoat form.

(1-1) Fixability 10 seconds after recording, the above sample was loaded with sylbon paper on the recorded material, and the sillbon paper was pulled with a weight of 40 g / cm ² loaded on the recording surface. At that time, it was visually observed whether or not the non-recording part (white background part) and the Sylbon paper of the recording medium were stained by rubbing of the recording part, and evaluated according to the following criteria.
A: Dirt due to rubbing is not seen.
B: Almost no dirt due to rubbing.
C: Dirt due to rubbing is noticeable.

(1-2) Marker resistance One minute after recording, a yellow fluorescent pen (Spotlight Yellow; manufactured by Pilot) is used to mark the recording portion once with normal writing pressure, and the presence or absence of characters is visually observed. And evaluated according to the following criteria.
A: Character disturbance due to the marker does not occur.
B: Character disturbance due to the marker occurs slightly.
C: Character disturbance due to the marker is remarkably generated.

(2) Ink storage stability over time A predetermined ink was put in a Teflon (registered trademark) container and sealed. This was stored in an oven at 60 ° C. for 1 month. The viscosity of the pigment in the ink before and after storage was measured, and the rate of change from the initial value was evaluated according to the following criteria.
A: The measured value after storage is less than 10% of the initial measured value.
B: The measured value after storage is 10% or more and less than 30% with respect to the initial measured value.
C: The measured value after storage is 30% or more of the initial measured value.

(3) Discharge stability Using the above-described recording apparatus, horizontal ruled lines were continuously recorded on PPC paper (manufactured by Canon) with a predetermined ink, and the line thickness and twist were visually evaluated.
A: There is no change in the thickness of the line, and there is no twist.
B: Although there is a slight thinning of the line, there is no problem in actual use.
C: There is a thin line, and some distortion is seen.

以上のように本発明のインクは、インクの硬化性能、インクの経時保存安定性及び吐出安定性に優れている。

As described above, the ink of the present invention is excellent in ink curing performance, ink storage stability over time, and ejection stability.

FIG. 2 is a diagram schematically illustrating the front of a suitable recording apparatus used in the present invention.

Explanation of symbols

1: Ink cartridge unit for storing ink of the present invention 2: Head unit attached with an ink cartridge for actually recording 3: Lamp unit for irradiating ultraviolet rays for curing 4: Head unit and drive unit for driving the lamp unit 5: Paper discharge unit for conveying the recording medium to be recorded

Claims (11)

An active energy ray-curable aqueous ink containing at least water and a polymerizable substance, wherein the polymerizable substance is a water-soluble polymerizable substance represented by the following general formula (I): Water based ink.

(In the general formula (I), Z represents a tetracarboxylic acid residue. Of the three, at least two Y represent the following general formula (II), and 0 to 2 Y represent —OM. Each M independently represents a hydrogen atom or an alkali metal.

(In General Formula (II), A represents at least one selected from the group consisting of a substituted or unsubstituted ethylene oxide chain, a substituted or unsubstituted propylene oxide chain, and a substituted or unsubstituted alkylene group. X represents A hydrogen atom or a methyl group, provided that the total number of ethylene oxide chains and propylene oxide chains in general formula (I) is 1 to 15))   The active energy ray-curable water-based ink according to claim 1, wherein the water-based ink further contains a water-soluble polymerization initiator. The active energy ray-curable aqueous ink according to claim 2, wherein the water-soluble polymerization initiator is at least one selected from the following general formulas (III), (V) to (VIII).

(In the general formula (III), R ₂ represents an alkyl group, a phenyl group (unsubstituted or halogen, an alkyl group, an alkyloxy group, a sulfonic acid group (—SO ₃ M), a carboxyl group (—CO ₂ M), a hydroxyl group) Group (—OM) and a salt thereof, and an arbitrary substituent selected from an atomic group represented by the following general formula (IV).

(In the general formula (IV), R ₅ represents — [CH ₂ ] _x2 — (x2 is 0 or 1), or a substituted or unsubstituted phenylene group. R ₆ represents a hydrogen atom, a sulfonic acid group (— SO ₃ M), a carboxyl group (—CO ₂ M), or a hydroxyl group (—OM), m2 represents an integer of 0 to 10, n2 represents 0 or 1. R ₃ represents an alkyloxy group or a phenyl group ( R ₄ represents an atomic group represented by the general formula (IV), and M 4 represents an atomic group represented by the general formula (IV), and is substituted by a substituent selected from a halogen, an alkyl group, and an alkyloxy group. Independently, hydrogen ions, alkali metal ions, equivalents of alkaline earth metal ions, or ammonium ions represented by HNR ₇ R ₈ R ₉ (R ₇ , R ₈ , R ₉ are independently hydrogen atom, alkyl Group, monohydroxyl substituted Means Kill group, or a phenyl group.) Represents a.)

(In general formula (V), m3 is an integer of 1 or more, n3 is an integer of 0 or more, and m3 + n3 is an integer of 1 to 8.)

(In General Formula (VI), R ₁₀ and R ₁₁ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group, and m4 is an integer of 5 to 10.)

(In General Formula (VII), R ₁₀ and R ₁₁ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₁₂ is — (CH ₂ ) _x — (x is 0 or 1). , —O— (CH ₂ ) _y — (y is 1 or 2), or a substituted or unsubstituted phenylene group, and M is a hydrogen atom or an alkali metal.

(In general formula (VIII), R ₁₀ and R ₁₁ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group, and M is a hydrogen atom or an alkali metal.)   The active energy ray-curable water-based ink according to any one of claims 1 to 3, wherein the water-based ink further contains a color material.   The active energy ray-curable water-based ink according to any one of claims 1 to 4, wherein the water-based ink is for inkjet recording.   A step of applying the active energy ray-curable aqueous ink according to any one of claims 1 to 5 to a recording medium, and irradiating the recording medium to which the aqueous ink has been applied with active energy rays to cure the aqueous ink. An inkjet recording method comprising the steps of:   The ink jet recording method according to claim 6, wherein the ink jet method is a method of discharging ink by the action of thermal energy.   An ink cartridge comprising an ink storage unit that stores the active energy ray-curable water-based ink according to any one of claims 1 to 5.   A recording unit comprising: an ink storage unit that stores the active energy ray-curable water-based ink according to any one of claims 1 to 5; and a recording head for discharging the ink.   An ink jet recording apparatus comprising: means for irradiating the water-based ink according to any one of claims 1 to 5 applied with an active energy ray to a recording medium. Active energy ray irradiation means, an ultraviolet radiation lamp having the following light source wavelength 450 nm, the irradiation intensity of the ultraviolet is, according to claim 10 which is 500 mW / cm ² or more 5,000 MW / cm ² or less in the range Inkjet recording device.

Images