JP2009083272A - Undercoat liquid, ink set for ink jet recording, and ink jet recording method - Google Patents

Abstract

【選択図】なしEven when a non-absorbable recording medium is used, ink bleeding is effectively suppressed, image uniformity among various recording media is high, and line width non-uniformity caused by droplet ejection interference is reduced. Ink set for ink jet recording, which can suppress the occurrence of color unevenness, is excellent in image design with wide color reproducibility, is fast in curability, has no problem of blocking, and has excellent productivity and handleability. The undercoating liquid used in the invention and an ink jet recording method are provided.
An undercoat liquid comprising a radically polymerizable compound, a photopolymerization initiator, and a sensitizer represented by the formula (I) or (II) is used.

[Selection figure] None

Description

  The present invention relates to an undercoat liquid, an ink set for ink jet recording, and an ink jet recording method, and more particularly to an undercoat liquid, an ink set for ink jet recording, and an ink jet recording method suitable for forming a high-quality image at high speed.

  An ink jet system that ejects ink in droplets from an ink ejection port is used in many printers because it is small and inexpensive, and can form an image without contact with a recording medium. Among these inkjet methods, the piezo inkjet method that ejects ink using deformation of piezoelectric elements and the thermal inkjet method that ejects ink droplets using the boiling phenomenon of ink due to thermal energy are high resolution and high-speed printability. It has the characteristic that it is excellent in.

  Currently, high speed, high image quality, and fixability to recording media are important issues when ink is ejected onto non-water-absorbing recording media such as plain paper or plastic by inkjet printers. ing.

Ink jet recording is a method in which ink droplets are ejected according to image data, and lines are formed on the recording medium or images are formed on the recording medium. When recording, if it takes time to dry the droplets after droplet ejection or penetrate into the recording medium, the image is likely to bleed, and mixing between adjacent ink droplets on the recording medium This causes a problem in practical use such as the formation of sharp images and hinders the formation of sharp images. When mixing between droplets, adjacent droplets that have been struck are united to cause movement of the droplets, so that they deviate from the landing position, and when drawing thin lines, the line width is uneven. When a colored surface is drawn, color unevenness or the like occurs (hereinafter referred to as droplet ejection interference). In addition, since the degree of unevenness of the line width and the occurrence of color unevenness on the colored surface varies depending on the ink absorbability and wettability of the surface of the recording medium, various recording media can be used even if the ink used and its discharge conditions are constant. There was also a problem that the images were different.
In addition to the above problems, an image recorded on a non-absorbable recording medium is also problematic in terms of image fixability, such as being easily peeled off and inferior to scratching.

Various techniques have been proposed so far to solve the above problems.
For example, in order to give high-definition drawing properties, there is a method that uses a reactive two-component ink and causes both to react on the recording medium. For example, a liquid having a basic polymer is attached. Then, after applying a method of recording an ink containing an anionic dye (see, for example, Patent Document 1) or a liquid composition containing a cationic substance, an ink containing an anionic compound and a coloring material is applied. A method (for example, refer to Patent Document 2) is disclosed.
In addition, UV curable ink is applied as the ink, and UV curable color ink dots ejected onto the recording medium are irradiated with ultraviolet rays in accordance with their respective ejection timings to increase the viscosity and adjacent dots do not mix with each other. There has been proposed an ink jet recording method in which pre-curing is performed to an extent, and then ultraviolet curing is further performed to perform main curing (see, for example, Patent Document 3).

  In addition, a radiation-curable white ink is uniformly applied as an undercoat layer on a transparent or translucent non-absorbable recording medium, solidified or thickened by irradiation, and then a radiation-curable color ink set is used. There has been proposed a technique (for example, see Patent Documents 4 and 5) that improves the problem of color ink visibility, bleeding, and differences in images between various recording media. In addition, a technique has been proposed in which a substantially transparent actinic ray curable ink is applied by an inkjet head in place of the radiation curable white ink (see, for example, Patent Documents 6, 7, and 8).

Japanese Unexamined Patent Publication No. 63-60783 JP-A-8-174997 JP 2004-42548 A JP 2003-145745 A JP 2004-42525 A JP 2005-96254 A JP 2006-137185 A JP 2006-137183 A

  However, the method described in Patent Document 2 can avoid the problem of droplet ejection interference and bleeding on a specific substrate, but is insufficient from the viewpoint of image fixability. On the other hand, in the method described in Patent Document 5, bleeding is suppressed and image fixability is improved. However, there remains a problem that images are different between various recording media. Insufficient line width and color unevenness due to mixing are insufficient. In addition, the methods described in Patent Documents 3 and 4 are insufficient for eliminating non-uniform line width and color unevenness caused by mixing between droplets. Furthermore, the methods described in Patent Documents 6, 7, and 8 still have problems such as non-uniform line width and color unevenness due to mixing between droplets. In addition, when the radical polymerization type ink set described in Patent Document 6 is used, the curability of the ink is insufficient, and stickiness of the cured film and film peeling become a problem. In the method described in Patent Document 7, ink dots are not easily connected to each other, and if the ink application amount is small, the color density may be lowered, and if the ink application amount is increased, the feeling of relay becomes a problem. Furthermore, when using the radiation-curable liquid layer and ink set described in Patent Documents 7 and 8, the amount of ink liquid applied per unit pixel is increased in order to print a high-density image or a high-saturation image, If the concentration of the colorant contained in the ink is increased, curing may be insufficient. In order to improve curability, when the concentration of the sensitizer described in Patent Documents 7 and 8 such as thioxanthone compound is increased (about 4 wt% or more), blocking when the printed matter is overlapped (printed surface and substrate surface overlapped) After storing together, when the printing surface and the substrate surface are peeled off again, tearing of the film on the printing surface or transfer of the image to the substrate occurs.

  The present invention has been made in view of the above, and even when any non-absorbable recording medium is used, ink bleeding is effectively suppressed, and the image uniformity between various recording media is high. In addition, it is possible to suppress the occurrence of non-uniform line width and color unevenness due to droplet ejection interference, excellent in image design with wide color reproducibility, fast curability, and productivity and handling without the problem of blocking. An object of the present invention is to provide an ink set for ink jet recording excellent in properties, an undercoat liquid used in the ink set, and an ink jet recording method, and to achieve the object.

The above problems of the present invention have been solved by the following means 1), 4), 8) and 9). It is listed together with 2), 3), 5) to 7), 10) and 11) which are preferred embodiments.
1) an undercoat liquid comprising a radically polymerizable compound, a photopolymerization initiator, and a sensitizer represented by the formula (I) or (II);

In the formula (I), X represents O, S, or NR ^a . n1 represents 0 or 1.
R ^a , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ each independently represent a hydrogen atom or a monovalent substituent, Of these, at least one contains an ethylenically unsaturated double bond.
In formula (II), X represents O, S or NR ^b . n2 represents 0 or 1.
R ^b , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ each independently represent a hydrogen atom or a monovalent substituent, and at least one of these One contains an ethylenically unsaturated double bond.
In the formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ may be bonded to each other to form a ring. In II), R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be linked together to form a ring.
2) The undercoat liquid according to 1), which contains at least one compound selected from the group consisting of an acylphosphine oxide compound and an α-aminoacetophenone compound as a photopolymerization initiator,
3) The undercoat liquid according to 1) or 2), wherein the undercoat liquid contains a surfactant,
4) An ink set for ink jet recording, comprising at least the undercoat liquid according to any one of 1) to 3) and a coloring liquid containing at least a radical polymerizable compound, a photopolymerization initiator, and a coloring agent,
5) The ink set for inkjet recording according to 4), wherein the coloring liquid contains a sensitizer represented by the formula (I) or (II).
6) The ink set for ink jet recording according to 4) or 5), wherein the coloring liquid contains at least one compound selected from the group consisting of an acylphosphine oxide compound and an α-aminoacetophenone compound as a photopolymerization initiator,
7) The ink set for ink jet recording according to any one of 4) to 6), wherein the surface tension γA of the colored liquid and the surface tension γB of the undercoat liquid satisfy a relationship of γA> γB.
8) In an ink jet recording method using the ink set for ink jet recording according to any one of 4) to 7), a step of applying an undercoat liquid onto a recording medium, and a step of semi-curing the undercoat liquid; A step of forming an image by discharging a colored liquid onto the semi-cured undercoat liquid, and an inkjet recording method comprising:
9) In the ink jet recording method using the ink set for ink jet recording according to any one of 4) to 7), when a secondary color is formed using the coloring liquid A and the coloring liquid B having different hues. An inkjet recording method comprising: a step of semi-curing the colored liquid A; and a step of discharging the colored liquid B onto the semi-cured colored liquid A.
10) The inkjet recording method according to 8) or 9), wherein the step of semi-curing the undercoat liquid and / or the step of semi-curing the coloring liquid A is performed by ultraviolet light irradiation.
11) The inkjet recording method according to 10), wherein the ultraviolet light for semi-curing the undercoat liquid and / or the ultraviolet light for semi-curing the coloring liquid A includes light in a range of at least 340 to 400 nm.

  According to the present invention, ink bleeding is effectively suppressed regardless of which non-absorbable recording medium is used, image uniformity between various recording media is high, and due to mixing between droplets. Thus, it was possible to provide an undercoat liquid capable of suppressing the occurrence of non-uniform line width and color unevenness and achieving excellent color reproducibility. In addition, it was possible to provide an ink jet recording method having no blocking and excellent fixability of an image to a recording medium.

The present invention will be described in detail below.
The undercoat liquid of the present invention is an undercoat liquid containing at least a radical polymerizable compound and a photopolymerization initiator, and the undercoat liquid contains a sensitizer represented by the above formula (I) or (II). Moreover, the ink set for inkjet recording of the present invention includes at least the undercoat liquid and a coloring liquid containing at least a radical polymerizable compound, a photopolymerization initiator, and a coloring agent.
(1) Ink set for ink jet recording The ink set for ink jet recording of the present invention includes a coloring liquid containing at least a radical polymerizable compound, a photopolymerization initiator, and a colorant, and at least a radical polymerizable compound and a photopolymerization initiator. An ink set for inkjet recording comprising at least an undercoat liquid containing a sensitizer represented by the following formula (I) or (II):

In the formula (I), X represents O, S, or NR ^a . n1 represents 0 or 1.
R ^a , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ each independently represent a hydrogen atom or a monovalent substituent, Of these, at least one contains an ethylenically unsaturated double bond.
In formula (II), X represents O, S or NR ^b . n2 represents 0 or 1.
R ^b , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ each independently represent a hydrogen atom or a monovalent substituent, and at least one of them Contains an ethylenically unsaturated double bond.
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are linked together to form a ring. You may do it.

In the formula (I), X represents O, S, or NR ^a , and X is more preferably S. n ₁ represents 0 or 1.
R ^a , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ each independently represent a hydrogen atom or a monovalent substituent, At least one of them is a polymerizable group that reacts with a radical.
It is preferable that one polymerizable group is contained, and R ² , R ⁶ , R ⁹ and R ¹⁰ are preferable as the substitution position of the polymerizable group.

When R ^a represents ^a monovalent substituent, R ^a represents an alkyl group or an acyl group as a substituent other than the polymerizable group. Monovalent substitution other than the polymerizable group when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ represent a monovalent substituent. Groups include halogen atoms, aliphatic groups, aromatic groups, heterocyclic groups, cyano groups, hydroxy groups, nitro groups, amino groups, alkylamino groups, alkoxy groups, aryloxy groups, amide groups, arylamino groups, ureidos. Group, sulfamoylamino group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, substituted sulfonyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy Group, silyloxy group, aryloxycarbonyl group, aryloxycarbonylamino group, imide group, heterocyclic thio group, substituted sulfini Group, a substituted phosphoryl group, an acyl group, a carboxy group or a sulfo group. Of these, an alkyl group, a halogen atom, an alkoxy group, an alkylthio group, and a carboxy group are more preferable. Particularly preferred are an alkyl group and a halogen atom.

  The unsaturated double bond is preferably an ethylenically unsaturated bond, and preferably an acryloyl group, a methacryloyl group, a styryl group, a vinyl group, a vinyl ester group (same as vinyloxycarbonyl group; the same shall apply hereinafter), Examples include allyl group. More preferred is an acryloyl group, a methacryloyl group, a vinyl ester group, and even more preferred is an acryloyl group.

In addition, as an alkyl group in case ^Ra in formula (I) represents a monovalent substituent, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group Preferred are those having 1 to 4 carbon atoms such as methyl group, ethyl group, propyl group and isopropyl group, and methyl group and ethyl group are particularly preferred. Similarly, as the acyl group, those having 1 to 4 carbon atoms such as an acetyl group, a propionyl group and a butyryl group are preferable, and an acetyl group and a propionyl group are particularly preferable. Examples of the alkyl group when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ represent a monovalent substituent include a methyl group and an ethyl group , A propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a t-butyl group are preferred, and a methyl group, an ethyl group, a propyl group, and an isopropyl group are more preferable. A methyl group and an ethyl group are preferable.
Similarly, the alkoxy group has 1 to 4 carbon atoms such as methoxy group, ethoxy group, hydroxyethoxy group, isopropoxy group, propoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and t-butoxy group. Preferably, a methoxy group, an ethoxy group, an isopropoxy group, and a propoxy group are more preferable, and a methoxy group and an ethoxy group are particularly preferable.

  Similarly, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, a chlorine atom, a bromine atom and an iodine atom are more preferred, and a chlorine atom and a bromine atom are particularly preferred.

In the formula (II), X represents O, S, or NR ^b , and X is more preferably S. n ₂ represents an integer of 0 or 1.
R ^b , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ each independently represent a hydrogen atom or a monovalent substituent, and at least one of these represents Contains ethylenically unsaturated double bonds.
One polymerizable group is preferably contained in the molecule, and R ¹² , R ¹⁷ , and R ¹⁸ are preferable as the substitution position of the polymerizable group.

When R ^b represents a monovalent substituent, R ^b represents an alkyl group or an acyl group as the monovalent substituent other than the polymerizable group. When R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ represent a monovalent substituent, the monovalent substituent includes a halogen atom, an aliphatic group, Aromatic group, heterocyclic group, cyano group, hydroxy group, nitro group, amino group, alkylamino group, alkoxy group, aryloxy group, amide group, arylamino group, ureido group, sulfamoylamino group, alkylthio group, Arylthio group, alkoxycarbonylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, substituted sulfonyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryloxycarbonyl group, aryl Oxycarbonylamino group, imide group, heterocyclic thio group, substituted sulfinyl group, substituted phosphoryl group , Acyl group, carboxy group or sulfo group. Of these, an alkyl group, a halogen atom, an alkoxy group, an alkylthio group, and a carboxy group are more preferable. Particularly preferred are an alkyl group and a halogen atom.
Preferred examples of the ethylenically unsaturated group include acryloyl group, methacryloyl group, styryl group, vinyl group, acrylamide group, methacrylamide group, and allyl group. More preferred is an acryloyl group, a methacryloyl group, and still more preferred is an acryloyl group.

In addition, as the alkyl group when R ^b in the formula (II) represents a monovalent substituent, the methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group Preferred are those having 1 to 4 carbon atoms, such as methyl, ethyl, propyl and isopropyl, more preferred are methyl and ethyl. Similarly, as the acyl group, those having 1 to 4 carbon atoms such as an acetyl group, a propionyl group and a butyryl group are preferable, and an acetyl group and a propionyl group are particularly preferable. Examples of the alkyl group when R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ represent a monovalent substituent include a methyl group, an ethyl group, a propyl group, and an isopropyl group. , N-butyl group, sec-butyl group, t-butyl group and the like having 1 to 4 carbon atoms are preferable, methyl group, ethyl group, propyl group, isopropyl group are more preferable, methyl group, ethyl group The group is particularly preferred.
Similarly, the alkoxy group has 1 to 4 carbon atoms such as methoxy group, ethoxy group, hydroxyethoxy group, isopropoxy group, propoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and t-butoxy group. Preferably, a methoxy group, an ethoxy group, an isopropoxy group, and a propoxy group are more preferable, and a methoxy group and an ethoxy group are particularly preferable.

Similarly, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, a chlorine atom, a bromine atom and an iodine atom are more preferred, and a chlorine atom and a bromine atom are particularly preferred.
Two of R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ may be linked to each other, for example, condensed to form a ring.
Examples of the ring structure in the case where these form a ring include a 5- or 6-membered aliphatic ring and an aromatic ring, and may be a heterocyclic ring containing an element other than a carbon atom. The rings may be further combined to form a binuclear ring, for example, a condensed ring. Further, these ring structures may further have a substituent exemplified when R ^{1 to} R ⁸ represent a monovalent substituent in the formula (I). N, O, and S can be mentioned as an example of a hetero atom in case the formed ring structure is a heterocyclic ring.

  Examples of sensitizers that can be used more suitably include sensitizers represented by the following formula (IA) or formula (II-A).

In the formula (IA), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ are each independently a hydrogen atom, halogen atom, hydroxy Represents a group, cyano group, nitro group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxy group or sulfo group.
Preferred examples of the polymerizable group that reacts with a radical include acryloyl group, methacryloyl group, styryl group, vinyl group, vinyl ester group, and allyl group. More preferred is an acryloyl group, a methacryloyl group, a vinyl ester group, and even more preferred is an acryloyl group.

In the formula (II-A), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ are each independently a hydrogen atom, halogen atom, hydroxy group, cyano group, nitro Represents a group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxy group or sulfo group.
The ethylenically unsaturated group is a polymerizable group that reacts with a radical, and preferably includes an acryloyl group, a methacryloyl group, a styryl group, a vinyl group, a vinyl ester group, and an allyl group. More preferred is an acryloyl group, a methacryloyl group, a vinyl ester group, and even more preferred is an acryloyl group.
In the formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ may be bonded to each other to form a ring. In II), R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ may be linked to each other, for example, condensed to form a ring.

Examples of the ring structure in the case where these form a ring include a 5- to 6-membered aliphatic ring, an aromatic ring and the like, and may be a heterocyclic ring containing an element other than a carbon atom. The rings may be further combined to form a binuclear ring, for example, a condensed ring. Further, these ring structures may further have a substituent exemplified when R ^{1 to} R ⁸ represent a monovalent substituent in the formula (I). N, O, and S can be mentioned as an example of a hetero atom in case the formed ring structure is a heterocyclic ring.

  Examples of sensitizers that can be used more suitably include sensitizers represented by the following formula (IB) or formula (II-B).

In the formula (IB), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, It represents a hydroxy group, cyano group, nitro group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxy group or sulfo group.
Preferred examples of the ethylenically unsaturated group include acryloyl group, methacryloyl group, styryl group, vinyl group, vinyl ester group, and allyl group. More preferred is an acryloyl group, a methacryloyl group, a vinyl ester group, and even more preferred is an acryloyl group.

In the formula (II-B), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each independently a hydrogen atom, halogen atom, hydroxy group, cyano group, nitro Represents a group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxy group or sulfo group.
Preferred examples of the ethylenically unsaturated group include acryloyl group, methacryloyl group, styryl group, vinyl group, vinyl ester group, and allyl group. More preferred is an acryloyl group, a methacryloyl group, a vinyl ester group, and even more preferred is an acryloyl group.
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are connected to each other, for example, fused together. To form a ring.

Examples of the ring structure in the case where these form a ring include a 5- to 6-membered aliphatic ring, an aromatic ring and the like, and may be a heterocyclic ring containing an element other than a carbon atom. The rings may be further combined to form a binuclear ring, for example, a condensed ring. Further, these ring structures may further have a substituent exemplified when R ^{1 to} R ⁸ represent a monovalent substituent in the formula (I). N, O, and S can be mentioned as an example of a hetero atom in case the formed ring structure is a heterocyclic ring.
Examples of the sensitizer that can be particularly preferably used include sensitizers represented by the following formula (III).

式（ＩＩＩ）においてＲ¹⁹、Ｒ²⁰、Ｒ²¹、Ｒ²²、Ｒ²³、Ｒ²⁴、Ｒ²⁵、及びＲ²⁶はそれぞれ独立に水素原子、又は一価の置換基を表し、少なくとも一つはエチレン性不飽和基を含む。エチレン性不飽和基としては、好ましくはアクリロイル基、メタクリロイル基、スチリル基、ビニル基、ビニルエステル基、アリル基などが挙げられ、より好ましくはアクリロイル基、メタクリロイル基、ビニルエステル基、さらに好ましくはアクリロイル基が挙げられる。
Ｒ¹⁹、Ｒ²⁰、Ｒ²¹、Ｒ²²、Ｒ²³、Ｒ²⁴、Ｒ²⁵、及びＲ²⁶が一価の置換基を表す場合の、一価の置換基としては、ハロゲン原子、脂肪族基、芳香族基、複素環基、シアノ基、ヒドロキシ基、ニトロ基、アミノ基、アルキルアミノ基、アルコキシ基、アリールオキシ基、アミド基、アリールアミノ基、ウレイド基、スルファモイルアミノ基、アルキルチオ基、アリールチオ基、アルコキシカルボニルアミノ基、スルホンアミド基、カルバモイル基、スルファモイル基、置換スルホニル基、アルコキシカルボニル基、ヘテロ環オキシ基、アゾ基、アシルオキシ基、カルバモイルオキシ基、シリルオキシ基、アリールオキシカルボニル基、アリールオキシカルボニルアミノ基、イミド基、ヘテロ環チオ基、置換スルフィニル基、置換ホスホリル基、アシル基、カルボキシ基又はスルホ基などが挙げられる。なかでも、より好ましくは、アルキル基、ハロゲン原子、アルコキシ基、アルキルチオ基、カルボキシ基である。特に好ましくは、アルキル基、ハロゲン原子である。
Ｒ¹⁹、Ｒ²⁰、Ｒ²¹、及びＲ²²は、それぞれ隣接する２つが互いに連結、例えば、縮合して環を形成していてもよい。
これらが環を形成する場合の環構造としては、５〜６員環の脂肪族環、芳香族環などが挙げられ、炭素原子以外の元素を含む複素環であってもよく、また、形成された環同士がさらに組み合わさって２核環、例えば、縮合環を形成していてもよい。さらにこれらの環構造は、前記式（Ｉ）において、Ｒ¹乃至Ｒ⁸が一価の置換基を表す場合に例示した置換基をさらに有していてもよい。形成された環構造が複素環である場合のヘテロ原子の例としては、Ｎ、Ｏ、及びＳを挙げることができる。
本発明に好適に用いることのできる、増感剤の具体例〔式（Ｉ）で表される化合物：例示化合物（Ｉ−１）〜（Ｉ−２０）〕〔式（ＩＩ）で表される化合物：例示化合物（ＩＩ−１）〜（ＩＩ−７５）〕を以下に示すが、本発明はこれらに限定されるものではない。

In the formula (III), R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , and R ²⁶ each independently represent a hydrogen atom or a monovalent substituent, and at least one of them is ethylene Contains a unsaturated group. The ethylenically unsaturated group is preferably an acryloyl group, a methacryloyl group, a styryl group, a vinyl group, a vinyl ester group, an allyl group, more preferably an acryloyl group, a methacryloyl group, a vinyl ester group, more preferably an acryloyl group. Groups.
When R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , and R ²⁶ represent a monovalent substituent, the monovalent substituent includes a halogen atom, an aliphatic group, Aromatic group, heterocyclic group, cyano group, hydroxy group, nitro group, amino group, alkylamino group, alkoxy group, aryloxy group, amide group, arylamino group, ureido group, sulfamoylamino group, alkylthio group, Arylthio group, alkoxycarbonylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, substituted sulfonyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryloxycarbonyl group, aryl Oxycarbonylamino group, imide group, heterocyclic thio group, substituted sulfinyl group, substituted phosphoryl group , Acyl group, carboxy group or sulfo group. Of these, an alkyl group, a halogen atom, an alkoxy group, an alkylthio group, and a carboxy group are more preferable. Particularly preferred are an alkyl group and a halogen atom.
Two of R ¹⁹ , R ²⁰ , R ²¹ , and R ²² may be linked to each other, for example, condensed to form a ring.
Examples of the ring structure in the case where these form a ring include a 5- to 6-membered aliphatic ring, an aromatic ring and the like, and may be a heterocyclic ring containing an element other than a carbon atom. The rings may be further combined to form a binuclear ring, for example, a condensed ring. Further, these ring structures may further have a substituent exemplified when R ^{1 to} R ⁸ represent a monovalent substituent in the formula (I). N, O, and S can be mentioned as an example of a hetero atom in case the formed ring structure is a heterocyclic ring.
Specific examples of sensitizers that can be suitably used in the present invention [compound represented by formula (I): exemplified compounds (I-1) to (I-20)] [represented by formula (II) Compound: Exemplary Compounds (II-1) to (II-75)] are shown below, but the present invention is not limited thereto.

By using this undercoat liquid or ink set for inkjet recording, ink bleeding is effectively suppressed even when any non-absorbable recording medium is used, and image uniformity between various recording media is high, Further, it is possible to suppress the occurrence of non-uniform line width and color unevenness due to droplet ejection interference (mixing between droplets). Furthermore, it is possible to provide an ink set for ink jet recording which is excellent in fixability of an image to a recording medium and excellent in color reproducibility and ink storage stability.
The main requirements constituting the ink set for inkjet recording of the present invention will be described in detail below.

(Coloring liquid)
Among the liquid compositions constituting the ink set for inkjet recording of the present invention, the colored liquid is a colored liquid containing at least a radical polymerizable compound, a photopolymerization initiator, and a colorant.
From the viewpoint of image fixability, the radical polymerizable compound is preferably added in an amount of 40% by weight or more and 98% by weight or less, and 50% by weight or more and 95% by weight based on the total weight of the colored liquid. % Or less is more preferable, and 60% by weight or more and 90% by weight or less is particularly preferable. It is preferable for the amount of radically polymerizable compound added to be in the above range since the curability is excellent and the viscosity is appropriate.

The addition concentration of the photopolymerization initiator is preferably 0.1 to 20.0% by weight, more preferably 0.5 to 18.0% by weight, still more preferably, based on the total weight of the colored liquid. 1.0 to 15.0% by weight. It is preferable that the addition amount of the photopolymerization initiator is within the above range because it is excellent in curability and is appropriate from the viewpoint of reducing surface stickiness.
The colorant is added in an amount of 50% by weight or less, more preferably 1% by weight or more and 30% by weight or less, and more preferably 2% by weight or more and 20% by weight or more based on the total weight of the color liquid. It is particularly preferable that the amount is not more than wt%. It is preferable that the addition amount of the colorant be within the above range since good image density and storage stability can be obtained.
From the viewpoint of enhancing the curability inside the film, the coloring liquid preferably contains a sensitizer represented by the formula (I) as a sensitizer. One of these sensitizers may be used alone, or two or more thereof may be used in combination.

The concentration of the sensitizer contained in the coloring liquid is preferably 0.1 to 15.0% by weight, more preferably 0.5 to 10.0 based on the total weight of the coloring liquid. % By weight, more preferably 1.0 to 8.0% by weight. It is preferable for the amount added to be in the above range since good curability inside the film can be obtained.
Further, from the viewpoint of further enhancing the curability inside the film, the coloring liquid preferably contains at least one compound selected from the group consisting of an acylphosphine oxide compound and an α-aminoacetophenone compound as a photopolymerization initiator. . The coloring liquid may contain either one of an acylphosphine oxide compound and an α-aminoacetophenone compound, or both may be used in combination.
The addition concentration of at least one compound selected from the group consisting of acylphosphine oxide compounds and α-aminoacetophenone compounds contained in the colored liquid is 0.1 to 20.0 weights with respect to the total weight of the colored liquid. %, More preferably 0.5 to 18.0% by weight, still more preferably 1.0 to 15.0% by weight. It is preferable for the amount added to be in the above range since good curability inside the film can be obtained.

  The colored liquid may be a liquid at room temperature, but from the viewpoint of appropriate droplet ejection by ink jetting, the viscosity at 25 ° C. is preferably 100 mPa · s or less, or the viscosity at 60 ° C. is preferably 30 mPa · s or less, 25 ° C. The viscosity at is preferably 60 mPa · s or less or the viscosity at 60 ° C. is more preferably 20 mPa · s or less, and the viscosity at 25 ° C. is particularly preferably 40 mPa · s or less or the viscosity at 60 ° C. is 15 mPa · s or less.

Similarly, the surface tension at 25 ° C. of the colored liquid is preferably 18 mN / m or more and 40 mN / m or less, more preferably 20 mN / m or more and 35 mN / m or less, and more preferably 22 mN / m or more and 32 mN / m from the viewpoint of ink jetting appropriateness. m or less is more preferable.
The “viscosity” here is a viscosity determined using a RE80 viscometer manufactured by Toki Sangyo Co., Ltd. The RE80 type viscometer is a conical rotor / plate type viscometer corresponding to the E type. The measurement was performed at a rotation speed of 10 rpm using the first rotor. However, for those having a viscosity higher than 60 mPa · s, the measurement was performed while changing the number of revolutions to 5 rpm, 2.5 rpm, 1 rpm, 0.5 rpm, or the like as necessary.
Here, the surface tension is measured at a liquid temperature of 25 ° C. by the Wilhelmy method using a commonly used surface tension meter (for example, surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd.). It is a measured value.

(Undercoat liquid)
Among the liquid compositions constituting the ink set for inkjet recording of the present invention, the undercoat liquid contains at least a radical polymerizable compound, a photopolymerization initiator, and a sensitizer represented by the formula (I) or (II). It is characterized by including.
From the viewpoint of image fixability, the radical polymerizable compound is preferably added in an amount of 40 wt.% Or more and 98 wt.% Or less, and 50 wt.% Or more and 95 wt. % Or less is more preferable, and 60% by weight or more and 90% by weight or less is particularly preferable. It is preferable for the amount of radically polymerizable compound added to be in the above range since the curability is excellent and the viscosity is appropriate.

The addition concentration of the photopolymerization initiator is preferably 0.1 to 20.0% by weight, more preferably 0.5 to 18.0% by weight, still more preferably, based on the total weight of the undercoat liquid. 1.0 to 15.0% by weight. It is preferable that the addition amount of the photopolymerization initiator is within the above range because it is excellent in curability and is appropriate from the viewpoint of reducing surface stickiness.
The addition concentration of the sensitizer contained in the undercoat liquid is preferably 0.1 to 15.0% by weight, more preferably 0.5 to 10.0 based on the total weight of the undercoat liquid. % By weight, more preferably 1.0 to 8.0% by weight. It is preferable for the amount added to be in the above range since good curability inside the film can be obtained.

Further, from the viewpoint of further enhancing the curability inside the film, the undercoat liquid preferably contains at least one compound selected from the group consisting of acylphosphine oxide compounds and α-aminoacetophenone compounds as a photopolymerization initiator. . The undercoat liquid may contain either one of an acylphosphine oxide compound and an α-aminoacetophenone compound, or both may be used in combination.
The addition concentration of at least one compound selected from the group consisting of acylphosphine oxide compounds and α-aminoacetophenone compounds contained in the undercoat liquid is 0.1 to 20.0% by weight relative to the total weight of the undercoat More preferably, it is 0.5-18.0 weight%, More preferably, it is 1.0-15.0 weight%. It is preferable for the amount added to be in the above range since good curability inside the film can be obtained.

From the viewpoint of uniformly coating the recording medium, the viscosity of the undercoat liquid at 25 ° C. is preferably 1000 mPa · s or less, or the viscosity at 60 ° C. is preferably 300 mPa · s or less, and the viscosity at 25 ° C. is 600 mPa · s or less. Alternatively, the viscosity at 60 ° C is more preferably 200 mPa · s or less, and the viscosity at 25 ° C is particularly preferably 400 mPa · s or less, or the viscosity at 60 ° C is 150 mPa · s or less.
Similarly, from the viewpoint of uniformly coating on the recording medium, the surface tension at 25 ° C. of the undercoat liquid is preferably 16 mN / m or more and 38 mN / m or less, more preferably 18 mN / m or more and 33 mN / m or less, and 20 mN / m. More preferably, it is 30 mN / m or less.

  Further, from the viewpoint of enhancing the color reproducibility of the image, the undercoat liquid preferably contains substantially no colorant or preferably contains a white pigment. The phrase “substantially does not contain a colorant” does not exclude the inclusion of a colorless and transparent dye / pigment, or a very small amount that cannot be visually recognized. The allowable amount is preferably 1% by weight or less, particularly preferably not contained, based on the total weight of the undercoat liquid. Moreover, the white pigment which can be preferably used is described in the item of (colorant).

Hereinafter, various components used in the coloring liquid and the undercoat liquid will be described.
(Radically polymerizable compound)
The radical polymerizable compound used for the coloring liquid and the undercoat liquid will be described.
As the polymerizable compound, various (meth) acrylates can be preferably used.
For example, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isoamyl stil acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, Butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, -Hydroxy-3-phenoxypropyl acrylate, 2-acryloylethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl phthalic acid, lactone-modified flexible acrylate, t- A monofunctional monomer such as butylcyclohexyl acrylate may be mentioned.

  Also, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexane Diol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, EO (ethylene oxide) adduct of bisphenol A, PO (propylene oxide) adduct of bisphenol A Diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, polytetramethylene glycol diacrylate Rate, trimethylolpropane triacrylate, EO modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxytriacrylate, caprolactone modified trimethylolpropane triacrylate And polyfunctional monomers such as pentaerythritol ethoxytetraacrylate and caprolactone-modified dipentaerythritol hexaacrylate.

  In addition, polymerizable oligomers can be blended in the same manner as the monomer. Examples of the polymerizable oligomer include epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, polyester acrylate, and linear acrylic oligomer.

  As the radically polymerizable compound constituting the coloring liquid and the undercoat liquid, the radically polymerizable compounds listed above can be appropriately used. From the viewpoint of improving the flexibility and abrasion resistance of the cured product, the radically polymerizable compound is used. Are preferably monofunctional cyclic (meth) acrylates, and more preferably any one of the following compounds (M-1 to M-29).

(Photopolymerization initiator)
As the photopolymerization initiator contained in the colored liquid and undercoat liquid of the present invention, known radical polymerization initiators can be used in addition to the above-mentioned acylphosphine oxide compound and α-aminoacetophenone compound. The photopolymerization initiator that can be used in the present invention may be used alone or in combination of two or more.
The photopolymerization initiator that can be used in the present invention is a compound that generates a polymerization initiating species upon irradiation with actinic radiation. Examples of the actinic radiation include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays. However, ultraviolet rays or visible rays are preferable from the viewpoint of device cost and operational safety.

  As the specific photopolymerization initiator, those known to those skilled in the art can be used without limitation, and specifically, for example, Bruce M. et al. Monroe et al., Chemical Review, 93, 435 (1993). R. S. By Davidson, Journal of Photochemistry and biologic A: Chemistry, 73.81 (1993). J. P. Faussier “Photoinitiated Polymerization—Theory and Applications”: Rapra Review vol. 9, Report, Rapra Technology (1998). M. Tsunooka et al. , Prog. Polym. Sci. , 21, 1 (1996). Many are described. In addition, a large number of chemical amplification type photoresists and compounds used for photocationic polymerization are described in (Organic Electronics Materials Study Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), pages 187 to 192). ing. Further, F.I. D. Saeva, Topics in Current Chemistry, 156, 59 (1990). G. G. Maslak, Topics in Current Chemistry, 168, 1 (1993). H., et al. B. Shuster et al, JACS, 112, 6329 (1990). I. D. F. Eaton et al, JACS, 102, 3298 (1980). A group of compounds that undergo oxidative or reductive bond cleavage through interaction with the electronically excited state of the sensitizer as described in the above.

  Furthermore, as described above, from the viewpoint of further increasing the curability inside the film, the photopolymerization initiator of the present invention contains at least one compound selected from the group consisting of acylphosphine oxide compounds and α-hydroxyacetophenone compounds. It is preferable. Acylphosphine oxide compounds and α-hydroxyacetophenone compounds that can be preferably used are as follows.

<Α-Aminoacetophenone compound>
The α-aminoacetophenone compound may be used alone or in combination of two or more.
As the α-aminoacetophenone compound, a compound represented by the following formula (1) can be preferably used.

In the formula, X ¹ represents a group represented by the following (a), (b) or (c).

式中ｐは０又は１である。

In the formula, p is 0 or 1.

式中ｑは０乃至３の整数であり、ｒは０又は１である。

In the formula, q is an integer of 0 to 3, and r is 0 or 1.

In the formula, Y represents a hydrogen atom, a halogen atom, an OH group, or an alkyl group having 1 to 12 carbon atoms (note that unless otherwise specified, an alkyl group means a linear or branched alkyl group. The same applies to the invention.), An alkoxy group having 1 to 12 carbon atoms, an aromatic ring group, or a heterocyclic group. A preferable example of the aromatic ring group is a phenyl group or a naphthyl group. Moreover, as said heterocyclic group, a furyl group, a thienyl group, or a pyridyl group can be illustrated preferably.
The alkyl group, alkoxy group, aromatic ring group, and heterocyclic group in Y may have a substituent.
Examples of the substituent that the alkyl group in Y may have include an OH group, a halogen atom, —N (X ¹⁰ ) ₂ (wherein two X ¹⁰ are independently a hydrogen atom, an alkyl having 1 to 8 carbon atoms). Group, an alkenyl group having 3 to 5 carbon atoms, a phenylalkyl group having 7 to 9 carbon atoms, a hydroxyalkyl group having 1 to 4 carbon atoms, or a phenyl group.), An alkoxy having 1 to 12 carbon atoms group, -COOR (R represents an alkyl group having 1 to 18 carbon _{atoms.), - CO (OCH 2} OCH 2) n OCH 3 (. n represents an integer of 1 to 20), or, -OCOR (R represents an alkyl group having 1 to 4 carbon atoms).
As the substituent that the alkoxy group in Y may have, —COOR (R represents an alkyl group having 1 to 18 carbon atoms) or —CO (OCH ₂ CH ₂ ) _n OCH ₃ (n Represents an integer of 1 or more and 20 or less.
As the substituent that the aromatic ring group or heterocyclic group in Y may have, — (OCH ₂ CH ₂ ) _n OH (n represents an integer of 1 or more and 20 or less), — (OCH ₂ CH ₂ ) _N OCH ₃ (n represents an integer of 1 to 20), an alkylthio group having 1 to 8 carbon atoms, a phenoxy group, and —COOR (R represents an alkyl group having 1 to 18 carbon atoms), _{-CO (OCH 2 CH 2) n} OCH 3 (n represents an integer of 1 to 20.), a phenyl group, or, benzyl groups.
If possible, these substituents may have two or more, and if possible, the substituents may be further substituted.
In the formula, X ¹² represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. X ¹³ , X ¹⁴ and X ¹⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. X ¹³ and X ¹⁴ may be cross-linked to form an alkylene group having 3 to 7 carbon atoms.

In the formula, X ² represents the same group as X ¹ , a cycloalkyl group having 5 or 6 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or a phenyl group.
The alkyl group and phenyl group in X ² may have a substituent.
Examples of the substituent that the alkyl group in X ² may have include an alkoxy group having 1 to 4 carbon atoms, a phenoxy group, a halogen atom, and a phenyl group.
Examples of the substituent that the phenyl group in X ² may have include a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.
If possible, these substituents may have two or more, and if possible, the substituents may be further substituted.
In the formula, X ¹ and X ² may be cross-linked to form a group represented by the following formula.

In the formula, X ¹³ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 5 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, or a phenylalkyl having 7 to 9 carbon atoms. Represents a group.
The alkyl group, alkenyl group, cycloalkyl group and phenylalkyl group in X ¹³ may have a substituent, such as an OH group, an alkoxy group having 1 to 4 carbon atoms,- CN or -COOR (R represents an alkyl group having 1 to 4 carbon atoms).
In the formula, X ¹⁴ is an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 5 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, a phenylalkyl group having 7 to 9 carbon atoms, or phenyl Represents a group.
The alkyl group, alkenyl group, cycloalkyl group, phenylalkyl group, and phenyl group in X ¹⁴ may have a substituent.
Examples of the substituent that the alkyl group, alkenyl group, cycloalkyl group, and phenylalkyl group in X ¹⁴ may have include an OH group, an alkoxyl group having 1 to 4 carbon atoms, —CN, or —COOR. (R represents an alkyl group having 1 to 4 carbon atoms). When the alkyl group denoted by X ¹⁴ has a substituent, the number of carbon atoms in the alkyl group that is substituted is preferably 2 to 4.
Examples of the substituent that the phenyl group in X ¹⁴ may have include a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or —COOR (where R is 1 carbon atom). Represents an alkyl group of 4 or less.).
Here, X ¹³ and X ¹⁴ are cross-linked to form an alkylene group having 1 to 7 carbon atoms, a phenyl alkylene group having 7 to 10 carbon atoms, an o-xylylene group, a 2-butenylene group, or 2 or 3 oxa- or aza-alkylene groups may be formed.
X ¹³ and X ¹⁴ may be cross-linked to form an alkylene group having 3 to 7 carbon atoms.
The alkylene group formed by crosslinking X ¹³ and X ¹⁴ is, as a substituent, an OH group, an alkoxy group having 1 to 4 carbon atoms, or —COOR (R represents an alkyl having 1 to 4 carbon atoms). .), And —O—, —S—, —CO—, or —N (X ¹⁶ ) — (X ¹⁶ is a hydrogen atom, having 1 to 12 carbon atoms) in the bond. An alkyl group, or 1 or 2 or more -O- in a bonding chain, an alkenyl group having 3 to 5 carbon atoms, a phenylalkyl group having 7 to 9 carbon atoms, a hydroxyalkyl group having 1 to 4 carbon atoms, —CH ₂ CH ₂ CN, —CH ₂ CH ₂ COOR (where R represents an alkyl group having 1 to 4 carbon atoms), an alkanoyl group having 2 to 8 carbon atoms or a benzoyl group intervening 1 or more carbon atoms Represents an alkyl group of 12 or less.) Yes.
In the formula, X ⁵ , X ⁶ , X ⁷ , X ⁸ and X ⁹ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 or 6 carbon atoms, a phenyl group, benzyl group, a benzoyl group, -OX ¹⁷ group, -SX ¹⁸ group, -SO-X ¹⁸ group, -SO ₂ -X ^{18 group, -N (X 19) (X} 20) group, -NH-SO ₂ -X ²¹ groups or a group represented by the following formula is represented.

Wherein, Z is -O -, - S -, - N (X 10) -X 11 -N (X 10) - or a group represented by the following formula. X ¹ , X ² , X ³ and X ⁴ have the same meanings as in the formula (1).

In the formula, X ¹⁰ is the same as described above, X ¹¹ is a linear or branched alkylene group having 2 to 16 carbon atoms, or one or more —O—, —S—, or —N in these chains. (X ¹⁰ ) — represents a linear or branched alkylene group having 2 to 16 carbon atoms (X ¹⁰ is the same as described above).
X ¹⁷ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, — (CH ₂ CH ₂ O) _n H (n is an integer of 2 to 20), an alkanoyl group having 2 to 8 carbon atoms, and 3 carbon atoms. Alkenyl group having 12 or less, cyclohexyl group, hydrocyclohexyl group, phenyl group, phenylalkyl group having 7 to 9 carbon atoms, or —Si (R ⁴ ) _r (R ⁵ ) _3-r (R ⁴ is carbon number) 1 to 8 alkyl groups, R ⁵ represents a phenyl group, and r represents 1, 2 or 3).
The alkyl group and phenyl group in X ¹⁷ may have a substituent.
As the substituent that the alkyl group for X ¹⁷ may have, —CN, —OH, an alkoxy group having 1 to 4 carbon atoms, an alkenyloxy group having 3 to 6 carbon atoms, —OCH ₂ CH ₂ CN , —CH ₂ CH ₂ COOR (R represents an alkyl group having 1 to 4 carbon atoms), —COOH, or —COOR (R represents an alkyl group having 1 to 4 carbon atoms). . When the alkyl group denoted by X ¹⁷ has a substituent, the carbon number of the alkyl group is substituted is preferably 1 or more and 6 or less.
Examples of the substituent that the phenyl group in X ¹⁷ may have include a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.
X ¹⁸ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 12 carbon atoms, a cyclohexyl group, a phenyl group, or a phenylalkyl group having 7 to 9 carbon atoms.
The alkyl group and phenyl group in X ¹⁸ may have a substituent.
The substituent which the alkyl group in X ¹⁸ may have is —SH, —OH, —CN, —COOR (R represents an alkyl group having 1 to 4 carbon atoms), 1 to 4 carbon atoms. Or an —OCH ₂ CH ₂ CN, or —OCH ₂ CH ₂ COOR (wherein R represents an alkyl having 1 to 4 carbon atoms).
Examples of the substituent that the phenyl group in X ¹⁸ may have include a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.
X ¹⁹ and X ²⁰ are each independently a hydrogen atom; an alkyl group having 1 to 12 carbon atoms; a hydroxyalkyl group having 2 to 4 carbon atoms; an alkoxyalkyl group having 2 to 10 carbon atoms; The following alkenyl groups; a cycloalkyl group having 5 to 12 carbon atoms; a phenylalkyl group having 7 to 9 carbon atoms; a phenyl group; a halogen atom; an alkyl group having 1 to 12 carbon atoms; A phenyl group substituted by an alkoxy group; or an alkanoyl group having 2 or 3 carbon atoms; or a benzoyl group. X ¹⁹ and X ²⁰ are cross-linked to form an alkylene group having 2 to 8 carbon atoms, or an OH group, an alkoxy group having 1 to 4 carbon atoms, or —COOR (R is an alkyl group having 1 to 4 carbon atoms. ) An alkylene group having 2 to 8 carbon atoms substituted by a group; an alkylene group having 2 to 8 carbon atoms in which —O—, —S— or —N (X ¹⁶ ) — is interposed in the bond chain (X ¹⁶ may be the same as described above.
X ²¹ represents an alkyl group having 1 to 18 carbon atoms; phenyl group; naphthyl group; or a phenyl group substituted by a halogen atom, an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 8 carbon atoms; Represents a naphthyl group.

  It is more preferable that the formula (1) is represented by the formula (d).

In formula (d), X ¹ and X ² each independently represent a methyl group, an ethyl group, or a benzyl group, —NX ³ X ⁴ represents a dimethylamino group, a diethylamino group, or a morpholino group, and X ⁵ Represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkylthio group having 1 to 8 carbon atoms, a dimethylamino group, or a morpholino group. -NX ³ X ⁴ is a dimethylamino group Among these, or, more preferably morpholino group.

Furthermore, an acid adduct salt of the compound represented by the above formula (1) can also be used as the α-aminoacetophenone compound.
As commercially available α-aminoacetophenone compounds, polymerization initiators available from Ciba Specialty Chemicals under the trade names Irgacure 907 (IRGACURE 907), Irgacure 369 (IRGACURE 369), and Irgacure 379 (IRGACURE 379) are available. It can be illustrated.

Specific examples of the α-aminoacetophenone compound include the following compounds.
For example, 2-dimethylamino-2-methyl-1-phenylpropan-1-one, 2-diethylamino-2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino-1-phenylpropane- 1-one, 2-dimethylamino-2-methyl-1- (4-methylphenyl) propan-1-one, 2-dimethylamino-1- (4-ethylphenyl) -2-methylpropan-1-one, 2-dimethylamino-1- (4-isopropylphenyl) -2-methylpropan-1-one, 1- (4-butylphenyl) -2-dimethylamino-2-methylpropan-1-one, 2-dimethylamino -1- (4-methoxyphenyl) -2-methylpropan-1-one, 2-dimethylamino-2-methyl-1- (4-methylthiophenyl) propane- -One, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (IRGACURE 907), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane -1-one (IRGACURE 369), 2-benzyl-2-dimethylamino-1- (4-dimethylaminophenyl) -butan-1-one, 2-dimethylamino-2-[(4-methylphenyl) methyl] And -1- [4- (4-morpholinyl) phenyl] -1-butanone (IRGACURE 379).

<Acylphosphine oxide compound>
The acylphosphine oxide compound is preferably a compound represented by the following formula (2) or the following formula (3).

R ¹ and R ² in the formula (2) each independently represent an aliphatic group, an aromatic group, an aliphatic oxy group, an aromatic oxy group, or a heterocyclic group, and R ³ represents an aliphatic group or an aromatic group. Represents a group or heterocyclic group. R ¹ and R ² may combine to form a 5-membered to 9-membered ring. The ring structure may be a heterocyclic ring having an oxygen atom, a nitrogen atom, a sulfur atom or the like in the ring structure.
Examples of the aliphatic group represented by R ¹ , R ^2, or R ³ include an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aralkyl group, and a substituted aralkyl group. Among them, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aralkyl group, or a substituted aralkyl group is preferable, and an alkyl group and a substituted alkyl group are particularly preferable. The aliphatic group may be a cyclic aliphatic group or a chain aliphatic group. The chain aliphatic group may have a branch.
Examples of the alkyl group include linear, branched, and cyclic alkyl groups. The number of carbon atoms of the alkyl group is preferably 1 or more and 30 or less, and more preferably 1 or more and 20 or less. The preferred range of the number of carbon atoms in the alkyl part of the substituted alkyl group is the same as in the case of the alkyl group. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, neopentyl group, An isopropyl group, an isobutyl group, etc. are mentioned.
Examples of the substituent of the substituted alkyl group include —COOH (carboxyl group), —SO ₃ H (sulfo group), —CN (cyano group), halogen atom (for example, fluorine atom, chlorine atom, bromine atom), —OH. (Hydroxy group), C30 or less alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, benzyloxycarbonyl group), C30 or less alkylsulfonylaminocarbonyl group, arylsulfonylaminocarbonyl group, alkylsulfonyl group An arylsulfonyl group, an acylaminosulfonyl group having 30 or less carbon atoms, an alkoxy group having 30 or less carbon atoms (for example, a methoxy group, an ethoxy group, a benzyloxy group, a phenoxyethoxy group, a phenethyloxy group, etc.), Alkylthio groups (eg methylthio , Ethylthio group, methylthioethylthioethyl group, etc.), aryloxy groups having 30 or less carbon atoms (for example, phenoxy group, p-tolyloxy group, 1-naphthoxy group, 2-naphthoxy group, etc.), nitro group, alkoxycarbonyloxy group , Aryloxycarbonyloxy group, acyloxy group having 30 or less carbon atoms (for example, acetyloxy group, propionyloxy group, etc.), acyl group having 30 or less carbon atoms (for example, acetyl group, propionyl group, benzoyl group, etc.), carbamoyl group (For example, carbamoyl group, N, N-dimethylcarbamoyl group, morpholinocarbonyl group, piperidinocarbonyl group, etc.), sulfamoyl group (for example, sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfonyl group, piperidinyl) Nosulfonyl group), carbon number 0 or less aryl group (for example, phenyl group, 4-chlorophenyl group, 4-methylphenyl group, α-naphthyl group, etc.), substituted amino group (for example, amino group, alkylamino group, dialkylamino group, arylamino group, Diarylamino group, acylamino group, etc.), substituted ureido group, substituted phosphono group, heterocyclic group and the like. Here, the carboxyl group, the sulfo group, the hydroxy group, and the phosphono group may be in a salt state. In this case, the cation that forms a salt is a group that can form a cation, and is an organic cationic compound, a transition metal coordination complex cation (such as the compound described in Japanese Patent No. 2791143) or a metal cation (for example, Na ⁺ , K ⁺ , Li ⁺ , Ag ⁺ , Fe ²⁺ , Fe ³⁺ , Cu ⁺ , Cu ²⁺ , Zn ²⁺ , Al ^3+, etc.) are preferred.

Examples of the alkenyl group include linear, branched, and cyclic alkenyl groups. The number of carbon atoms of the alkenyl group is preferably 2 or more and 30 or less, and more preferably 2 or more and 20 or less. The alkenyl group may be a substituted alkenyl group having a substituent or an unsubstituted alkenyl group, and the preferred range of the number of carbon atoms in the alkenyl part of the substituted alkenyl group is the same as that of the alkenyl group. . Examples of the substituent for the substituted alkenyl group include the same substituents as those for the substituted alkyl group.
Examples of the alkynyl group include linear, branched, and cyclic alkynyl groups, and the number of carbon atoms of the alkynyl group is preferably 2 to 30, and more preferably 2 to 20. The alkynyl group may be a substituted alkynyl group having a substituent or an unsubstituted alkynyl group, and the preferred range of the number of carbon atoms in the alkynyl part of the substituted alkynyl group is the same as in the case of the alkynyl group. . Examples of the substituent for the substituted alkynyl group include the same substituents as those for the substituted alkyl group.
Examples of the aralkyl group include aralkyl groups having a linear, branched, or cyclic alkyl side chain, and the number of carbon atoms of the aralkyl group is preferably 7 or more and 35 or less, and more preferably 7 or more and 25 or less. . The aralkyl group may be a substituted aralkyl group having a substituent or an unsubstituted aralkyl group, and the preferred range of the number of carbon atoms in the aralkyl part of the substituted aralkyl group is the same as in the case of the aralkyl group. . Examples of the substituent for the substituted aralkyl group include the same substituents as those for the substituted alkyl group. In addition, the aryl part of the aralkyl group may have a substituent, and the substituent is the same as that of the alkyl group and a linear, branched or cyclic alkyl group having 30 or less carbon atoms. Can be illustrated.

Examples of the aromatic group represented by R ¹ , R ² or R ³ include an aryl group and a substituted aryl group. The number of carbon atoms of the aryl group is preferably 6 or more and 30 or less, and more preferably 6 or more and 20 or less. The preferable range of the number of carbon atoms in the aryl part of the substituted aryl group is the same as that of the aryl group. Examples of the aryl group include a phenyl group, an α-naphthyl group, a β-naphthyl group, and the like. Examples of the substituent of the substituted aryl group include the same substituents as those in the case of the substituted alkyl group and linear, branched or cyclic alkyl groups having 30 or less carbon atoms.
The aliphatic oxy group represented by R ¹ or R ² is preferably an alkoxy group having 1 to 30 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a butoxy group, an octyloxy group, and a phenoxyethoxy group. It is done. However, it is not limited to these.
The aromatic oxy group represented by R ¹ or R ² is preferably an aryloxy group having 6 to 30 carbon atoms, for example, phenoxy group, methylphenyloxy group, chlorophenyloxy group, methoxyphenyloxy group, octyl An oxyphenyloxy group etc. are mentioned. However, it is not limited to these.
The heterocyclic group represented by R ¹ , R ² or R ³ is preferably a heterocyclic group containing an N, O or S atom, for example, a pyridyl group, a furyl group, a thienyl group, an imidazolyl group, a pyrrolyl group or the like. Is mentioned.
In addition, the compound represented by the formula (2) is bonded to another compound represented by the formula (2) in R ¹ , R ² or R ³ to form a multimer having two or more acylphosphine structures. May be.

R ⁴ and R ⁶ in the formula (3) each independently represent an alkyl group, an aryl group, or a heterocyclic group, and R ⁵ represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, or a heterocyclic group. To express.
The alkyl group, aryl group, heterocyclic group, alkoxy group, and aryloxy group represented by R ⁴ , R ^5, or R ⁶ may have a substituent. The same substituents as in (2) can be mentioned.
The alkyl group, aryl group, heterocyclic group, alkoxy group and aryloxy group in the formula (3) have the same meaning as in the formula (2).
In addition, the compound represented by the formula (3) is bonded to another compound represented by the formula (3) in R ⁴ , R ⁵ or R ⁶ to form a multimer having two or more acylphosphine structures. May be.

  The compound represented by the formula (2) is more preferably a compound represented by the following formula (4).

In the formula (4), R ⁷ and R ⁸ each independently represent a phenyl group, a methoxy group or an isopropoxy group, and R ⁹ represents a 2,4,6-trimethylphenyl group or a 2,4-dimethylphenyl group. , 2-methylphenyl group (o-toluyl group), isobutyl group, or t-butyl group.

  The compound represented by the formula (3) is more preferably a compound represented by the following formula (5).

In the formula (5), R ¹⁰ and R ¹² each independently represents 2,4,6-trimethylphenyl group, 2,6-dimethylphenyl group, or 2,6-dimethoxyphenyl group, and R ¹¹ represents phenyl. Represents a group or a 2,4,4-trimethylpentyl group.

Examples of the acylphosphine oxide compound represented by the formula (2) or (3) include, for example, JP-B 63-40799, JP-B 5-29234, JP-A-10-95788, JP-A-10- Examples include compounds described in Japanese Patent No. 29997.
Specific examples of the acylphosphine oxide compound include the following compounds (Exemplary Compounds (P-1) to (P-26)), but the present invention is not limited to these.

  As the acylphosphine oxide compound, a monoacylphosphine oxide compound, a bisacylphosphine oxide compound, or the like can be used. As the monoacylphosphine oxide compound, a known monoacylphosphine oxide compound can be used. Examples thereof include monoacylphosphine oxide compounds described in JP-B-60-8047 and JP-B-63-40799. Specific examples include isobutyryl-methylphosphinic acid methyl ester, isobutyryl-phenylphosphinic acid methyl ester, pivaloyl-phenylphosphinic acid methyl ester, 2-ethylhexanoyl-phenylphosphinic acid methyl ester, pivaloyl-phenylphosphinic acid isopropyl ester, p. -Toluyl-phenylphosphinic acid methyl ester, o-toluyl-phenylphosphinic acid methyl ester, 2,4-dimethylbenzoyl-phenylphosphinic acid methyl ester, p-tert-butylbenzoyl-phenylphosphinic acid isopropyl ester, acryloyl-phenylphosphinic acid Methyl ester, isobutyryl-diphenylphosphine oxide, 2-ethylhexanoyl-diphenylphosphine oxide, o-to Yl-diphenylphosphine oxide, p-tertiarybutylbenzoyl-diphenylphosphine oxide, 3-pyridylcarbonyl-diphenylphosphine oxide, acryloyl-diphenylphosphine oxide, benzoyl-diphenylphosphine oxide, pivaloyl-phenylphosphinic acid vinyl ester, adipoyl-bis- Diphenylphosphine oxide, pivaloyl-diphenylphosphine oxide, p-toluyl-diphenylphosphine oxide, 4- (tertiarybutyl) -benzoyl-diphenylphosphine oxide, 2-methylbenzoyl-diphenylphosphine oxide, 2-methyl-2-ethylhexanoyl -Diphenylphosphine oxide, 1-methyl-cyclohexanoyl-diphenylphosphine Examples thereof include oxide, pivaloyl-phenylphosphinic acid methyl ester, and pivaloyl-phenylphosphinic acid isopropyl ester.

  A known bisacylphosphine oxide compound can be used as the bisacylphosphine oxide compound. Examples thereof include bisacylphosphine oxide compounds described in JP-A-3-101686, JP-A-5-345790, and JP-A-6-298818. Specific examples include bis (2,6-dichlorobenzoyl) -phenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -4- Ethoxyphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2-naphthylphosphine oxide, bis (2,6-dichlorobenzoyl) -1- Naphthylphosphine oxide, bis (2,6-dichlorobenzoyl) -4-chlorophenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2,4-dimethoxyphenylphosphine oxide, bis (2,6-dichlorobenzoyl)- Decylphosphine oxide, bis (2 , 6-dichlorobenzoyl) -4-octylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-dimethylphenylphosphine oxide, Bis (2,6-dichloro-3,4,5-trimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dichloro-3,4,5-trimethoxybenzoyl) -4-ethoxy Phenylphosphine oxide, bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -4-ethoxyphenylphosphine oxide, bis (2-methyl-1- Naphthoyl) -2-naphthylphosphine oxide, bis (2-methyl- 1-naphthoyl) -4-propylphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2-methoxy-1-naphthoyl) -4-ethoxyphenylphosphine oxide, Examples thereof include bis (2-chloro-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide.

  Among these, in the present invention, as the acylphosphine oxide compound, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (IRGACURE 819: manufactured by Ciba Specialty Chemicals), bis (2,6-dimethoxybenzoyl)- 2,4,4-trimethylpentylphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (DAROCUR TPO: manufactured by Ciba Specialty Chemicals, LUCIRIN TPO: manufactured by BASF) and the like are preferable.

<Other photopolymerization initiators>
The coloring liquid and the undercoat liquid can each contain other photopolymerization initiators. The polymerization initiator preferably contains a radical polymerization initiator. Examples of other polymerization initiators include α-hydroxyacetophenone compounds and oxime ester compounds.

(Coloring agent)
In the present invention, the coloring liquid contains at least a coloring agent. On the other hand, the undercoat liquid preferably contains substantially no colorant, or preferably contains a white pigment.
There is no restriction | limiting in particular in the coloring agent which can be used in this invention, According to a use, well-known various pigments and dyes can be selected suitably and can be used. Among these, the colorant and optionally the colorant contained in the undercoat liquid are preferably pigments from the viewpoint of excellent light resistance.

The pigment preferably used in the present invention will be described.
The pigment is not particularly limited, and all commercially available organic pigments and inorganic pigments, and those obtained by dyeing resin particles with a dye can be used. Furthermore, commercially available pigment dispersions and surface-treated pigments, for example, pigments dispersed in an insoluble resin or the like as a dispersion medium, or those obtained by grafting a resin on the pigment surface, etc., impair the effects of the present invention. It can be used as long as it is not.
As these pigments, for example, Seijiro Ito, “Dictionary of Pigments” (published in 2000), W. Herbst, K. Hunger, Industrial Organic Pigments, JP 2002-12607 A, JP 2002-188025 A, Examples thereof include pigments described in JP2003-26978A and JP2003-342503A.

  Specific examples of organic pigments and inorganic pigments that can be used in the present invention include C.I. I. Pigment Yellow 1 (Fast Yellow G, etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Pigment yellow 180, C.I. I. Non-benzidine type azo pigments such as C.I. Pigment Yellow 200 (Novoperm Yellow 2HG); I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  C. As a thing which exhibits red or magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment Violet 19 (unsubstituted quinacridone, CINQUASIA Magenta RT-355T; manufactured by Ciba Specialty Chemicals), C.I. I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

As a pigment exhibiting blue or cyan, C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Pigment blue 15, C.I. I. Phthalocyanine pigments such as C.I. Pigment Blue 15: 3 (IRGALITE BLUE GLO; manufactured by Ciba Specialty Chemicals) (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).
As a pigment exhibiting green, C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. And azo metal complex pigments such as CI Pigment Green 8 (Nitroso Green).
As a pigment exhibiting an orange color, C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. And anthraquinone pigments such as CI Pigment Orange 51 (dichloropyrantron orange).

  Examples of the black pigment include carbon black, titanium black, and aniline black. Examples of the carbon black include SPECIAL BLACK 250 (manufactured by Degussa).

Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) can be used.
Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a large hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

Dispersing colorants, for example, bead mill, ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, etc. Can be used.
When dispersing the colorant, a dispersant such as a surfactant can be added.
Moreover, when adding a coloring agent, it is also possible to use the synergist according to various coloring agents as a dispersing aid as needed. The dispersion aid is preferably added in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the colorant.

  In the coloring liquid and the undercoat liquid, as a dispersion medium for various components such as a colorant, a solvent may be added, or the polymerizable compound which is a low molecular weight component without a solvent may be used as the dispersion medium. However, the coloring liquid and the undercoating liquid are preferably active energy ray-curable liquids, and are preferably solvent-free in order to cure the coloring liquid and / or the undercoating liquid after being applied onto the recording medium. . This is because when the solvent remains in the image formed from the cured coloring liquid or undercoat liquid, the solvent resistance is deteriorated or a problem of VOC (Volatile Organic Compound) of the remaining solvent occurs. From such a viewpoint, it is preferable to use a polymerizable compound as the dispersion medium, and in particular, to select a polymerizable compound having the lowest viscosity from the viewpoint of improving dispersibility and handling properties of the ink composition.

The average particle size of the colorant used here is preferably 0.01 μm or more and 0.4 μm or less, and more preferably 0.02 μm or more and 0.2 μm or less, because the finer the color, the better the color developability. It is preferable to set the colorant, dispersant, dispersion medium, dispersion conditions, and filtration conditions so that the maximum particle diameter is 3 μm or less, preferably 1 μm or less. By controlling the particle size, clogging of the head nozzle can be suppressed, and the storage stability of the colored liquid and the undercoat liquid, the transparency of the colored liquid and the undercoat liquid, and the curing sensitivity can be maintained. In the present invention, by using the dispersant having excellent dispersibility and stability, a uniform and stable dispersion can be obtained even when a fine particle colorant is used.
The particle size of the colorant in the color liquid and undercoat liquid can be measured by a known measurement method. Specifically, it can be measured by a centrifugal sedimentation light transmission method, an X-ray transmission method, a laser diffraction / scattering method, and a dynamic light scattering method. In the present invention, a value obtained by measurement using a laser diffraction / scattering method is employed.

(Relationship between surface tension of coloring liquid and undercoat liquid)
From the viewpoint of preventing bleeding of the formed image for a long time until the coloring liquid applied on the recording medium is started, the surface tension of the undercoat liquid is set to γA (mN / m). When the tension is γB (mN / m), the relationship between γA and γB preferably satisfies the relationship γA> γB, more preferably satisfies the relationship γA−γB ≧ 1, and γA−γB ≧ 2. It is particularly preferable to satisfy this relationship.
The surface tension is a value measured at a liquid temperature of 25 ° C. by the Wilhelmy method using a commonly used surface tension meter (for example, surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd.). is there.

<Surfactant>
The coloring liquid and the undercoat liquid preferably contain a surfactant in order to satisfy the above relational expression, and in particular, the undercoat liquid preferably contains a surfactant.
Examples of the surfactant used in the present invention include the following surfactants. Examples thereof include those described in JP-A Nos. 62-173463 and 62-183457. Specifically, for example, anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene -Nonionic surfactants such as polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used as the known surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.
In particular, the surfactant used in the present invention is not limited to the above-described surfactant, and may be any additive capable of efficiently reducing the surface tension with respect to the added concentration.

(Other additives)
In the coloring liquid and undercoat liquid in the present invention, in addition to the polymerizable compound and the polymerization initiator, various additives can be used in combination according to the purpose. For example, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image. Further, an antioxidant can be added to improve the stability of the coloring liquid and the undercoat liquid.
Furthermore, various organic and metal complex anti-fading agents, conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, dimethylamine hydrochloride for the purpose of controlling ejection properties, ink compositions and substrates In order to improve the adhesiveness, an extremely small amount of organic solvent can be added.
Moreover, various polymer compounds can be added to adjust film physical properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination.
In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film properties, tackifiers that do not inhibit the polymerization in order to improve adhesion to polyolefins, PET, etc. Can be contained.

(2) Inkjet recording method <Recording method>
In the ink jet recording method of the present invention, an ink set for ink jet recording composed of a colored liquid for forming an image and an undercoat liquid used as an undercoat liquid is used.
The recording method includes (i) a step of applying an undercoat liquid onto a recording medium, (ii) a step of semi-curing the undercoat liquid, and (iii) discharging a colored liquid onto the semi-cured undercoat liquid. Image forming, and at least three processes.
From the viewpoint of improving the abrasion resistance and adhesion of the image, it is preferable to include (iv) a step of completely curing the image after the above three steps. Moreover, it is preferable that the colored liquid in the present invention uses a plurality of colored liquids as a multicolor ink set. When a multicolor ink set is used in this way, it is more preferable that the step of semi-curing the colored liquid droplets after applying the colored liquid of each color to the recording medium is more preferable. For example, when forming a secondary color using the coloring liquid A and the coloring liquid B having different hues, the coloring liquid B is applied onto the semi-cured coloring liquid A after the step of semi-curing the coloring liquid A. It is preferable that the discharging step be performed.

Therefore, the most preferable step of the ink jet recording method of the present invention is as shown in FIG.
FIG. 1 shows a conceptual diagram of an ink jet recording method that can be suitably used in the present invention. This will be described in detail below with reference to FIG.
The recording medium 6 is conveyed by recording medium conveying means 7A and 7B, and is conveyed from left to right in FIG.
The recording medium and the recording medium conveying means are not particularly limited, but in the present embodiment shown in FIG. 1, a plastic film is used as the recording medium, and the film unwinding as the recording medium conveying means. Machine (7A) and film winder (7B) are used.
In the first step, the undercoat liquid is applied onto the recording medium 6 by means 1 for applying the undercoat liquid. Examples of means for applying the undercoat liquid include a roll coater.
Subsequently, in the second step, the undercoat liquid applied on the recording medium 6 is semi-cured by means 2 for semi-curing the undercoat liquid. An example of means for semi-curing the undercoat liquid is an ultraviolet light source.
In the third step, a colored image is formed by means 3Y for applying a colored liquid onto the film of the undercoat liquid semi-cured on the recording medium 6. In FIG. 1, a yellow coloring liquid is applied to form a yellow image. As the means 3Y for applying the yellow coloring liquid, a yellow ink jet recording head can be exemplified. In the fourth step, the yellow colored liquid is semi-cured by means 4Y for semi-curing the colored liquid applied in the third step. In FIG. 1, an ultraviolet light source is used as a means for semi-curing the colored liquid, and the yellow colored liquid applied on the film of the undercoat liquid is semi-cured.
In the fifth step, the cyan color liquid is applied by means 3C for applying the cyan color liquid onto the undercoat liquid and / or yellow liquid film semi-cured on the recording medium, thereby forming a cyan image. Examples of the means 3C for applying the cyan coloring liquid include a cyan ink jet recording head. In the sixth step, the colored liquid applied in the fifth step is semi-cured. In FIG. 1, an ultraviolet light source is used as the means 4C for semi-curing the cyan coloring composition, and the cyan coloring liquid applied on the undercoat liquid and / or the yellow coloring composition film is semi-cured.
Similarly, in the seventh step, after forming a magenta image on any of the undercoat liquid, yellow color liquid, and cyan color liquid by means 3M for applying a magenta color liquid, magenta coloring is performed in the eighth step. The applied magenta coloring liquid is semi-cured by means 4M for semi-curing the liquid.
Further, in the ninth step, a black image is formed by means 3K for applying a black color liquid onto any one of the undercoat liquid, yellow color liquid, cyan color liquid and magenta color liquid. In the tenth step, the black colored liquid is semi-cured by means 4K for semi-curing the black colored liquid.
Subsequently, in the eleventh step, the formed full-color image is completely cured by means 5 for completely curing the formed full-color image.
Here, it is possible to omit the tenth step, and in this case, the recording medium to which the last colored liquid has been applied is completely cured without going through a semi-curing step.
Next, each step will be described.

<Step of applying undercoat liquid on recording medium>
In the step of applying the undercoat liquid on the recording medium, the undercoat liquid is applied to the same area as the image formed by discharging colored liquid droplets on the recording medium or an area wider than the image. Is preferred.
The amount of the undercoat liquid applied (weight ratio per unit area) is within the range of 0.05 to 5 when the maximum droplet amount (per color) of the colored liquid composition is 1. Is preferable, the range of 0.07 to 4 is more preferable, and the range of 0.1 to 3 is particularly preferable.

In the inkjet recording method of the present invention, a coating device, an inkjet nozzle, or the like can be used as means for applying the undercoat liquid on the recording medium.
The coating apparatus is not particularly limited and can be appropriately selected from known coating apparatuses according to the purpose, for example, an air doctor coater, a blade coater, a lot coater, a knife coater, a squeeze coater, and an impregnation coater. , Reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, extrusion coater and the like. For details, see Yuji Harasaki's “Coating Engineering”.
Among these, from the viewpoint of apparatus cost, the application of the undercoat liquid onto the recording medium is preferably performed by application using a relatively inexpensive bar coater or spin coater, or by the ink jet method.

<Step of semi-curing undercoat liquid and / or colored liquid>
In the present invention, “semi-cured” means partially cured (partially cured), and is a state in which the undercoat liquid and / or the colored liquid is partially cured but not completely cured. Say. When the undercoat liquid applied on the recording medium (base material) or the colored liquid discharged onto the undercoat liquid is semi-cured, the degree of curing may be uneven. For example, it is preferable that the undercoating liquid and / or the coloring liquid is hardened in the depth direction.

  As a method of semi-curing the undercoat liquid and / or the colored liquid, (1) a basic compound is imparted to the acidic polymer, or an acidic compound or a metal compound is imparted to the basic polymer. A method using an agglomeration phenomenon, (2) an undercoat liquid and / or a colored liquid is prepared in advance to have a high viscosity, and a low boiling point organic solvent is added thereto to reduce the viscosity, and the low boiling point organic solvent is evaporated to obtain the original liquid (3) A method of returning to the original high viscosity by heating and cooling the undercoat liquid and / or coloring liquid prepared to a high viscosity, and (4) an undercoating liquid and / or coloring liquid. Examples include a known thickening method such as a method in which an active energy ray or heat is applied to cause a curing reaction. Among these, (4) a method in which an active energy ray or heat is applied to the undercoat liquid and / or the colored liquid to cause a curing reaction is preferable.

  The method of causing an active energy ray or heat to cause a semi-curing reaction is a method in which the polymerization reaction of the polymerizable compound on the surface of the undercoat liquid and / or the colored liquid applied to the recording medium is insufficiently performed.

  When polymerizing a radically polymerizable undercoat liquid or colored liquid in an atmosphere containing a large amount of oxygen such as in the air or in air partially substituted with an inert gas, it is necessary to suppress the radical polymerization of oxygen. There is a tendency that radical polymerization is inhibited on the surface of the undercoat liquid layer or colored liquid droplets (hereinafter also referred to as colored liquid droplets) applied on the recording medium. As a result, the semi-curing becomes non-uniform, the curing progresses more inside the undercoat liquid layer or the colored liquid droplets, and the surface curing tends to be delayed. Here, the undercoat liquid layer is a layer of the undercoat liquid applied on the substrate.

  Even when the cationic polymerizable undercoat liquid or colored liquid is polymerized in an atmosphere having moisture, the undercoat liquid layer or colored liquid droplets applied on the recording medium because of the action of inhibiting the cationic polymerization of moisture. Curing progresses more inside and tends to delay the curing of the surface.

In the present invention, when the radical photopolymerizable undercoating liquid or coloring liquid is used in the presence of radical polymerization-inhibiting oxygen and partially photocured, the undercoating liquid and / or the coloring liquid is cured more than the outside. More progress inside.
In particular, the surface of the undercoat liquid is more likely to inhibit the polymerization reaction due to the influence of oxygen in the air compared to the inside. Therefore, the undercoat liquid can be semi-cured by controlling the active energy ray or heat application conditions.

  Among these, semi-curing by irradiation with active energy rays is preferable. As the active energy ray, α ray, γ ray, electron beam, X ray, ultraviolet ray, visible light, infrared ray or the like can be used. Among these, ultraviolet rays or visible light is preferable, and ultraviolet rays are more preferable. Furthermore, although it depends on the absorption characteristics of the sensitizer, the peak wavelength of the active radiation is, for example, preferably 200 to 600 nm, more preferably 300 to 450 nm, and further preferably 340 to 400 nm. .

The amount of energy required for semi-curing the undercoat liquid and / or the coloring liquid varies depending on the type and content of the polymerization initiator, but when energy is applied by active energy rays, 1 to 500 mJ / cm ² is preferable. . In addition, when energy is applied by heating, it is preferable to heat for 0.1 to 1 second under the condition that the surface temperature of the recording medium is in a temperature range of 40 to 80 ° C.

Generation of active species due to decomposition of the polymerization initiator is promoted by application of active energy rays such as actinic light and heating, or heat, and polymerizability or cross-linkability caused by the active species is increased by increasing the active species or increasing the temperature. The curing reaction by polymerization or crosslinking of the material is accelerated.
Moreover, thickening (viscosity increase) can also be suitably performed by irradiation of actinic light or heating.

  When a colored liquid is ejected onto the semi-cured undercoat liquid, or a different colored liquid (especially a colored liquid having a different hue) is ejected onto the semi-cured colored liquid, it is obtained. Which has a positive technical effect on the quality of the printed material produced. Moreover, the action mechanism can be confirmed by observing the cross section of the printed matter.

When a colored liquid of about 12 pL (picoliter; the same applies below) was deposited on a semi-cured undercoat liquid having a thickness of about 5 μm provided on the substrate, the droplets were ejected at a high density. A portion (high concentration portion) will be described as an example.
FIG. 2 is a schematic cross-sectional view showing an embodiment of a printed matter obtained by depositing a colored liquid on a semi-cured undercoat liquid layer. In the production of the printed matter shown in FIG. 2, the undercoat liquid is semi-cured, and the substrate 16 side is more cured than the surface layer. FIG. 2 shows an undercoat layer 14 in which a coloring liquid is applied to a semi-cured undercoat liquid layer.
In this case, the following three features are observed in the cross section of the obtained image 10.
(1) A part of the colored liquid cured product 12 appears on the surface.
(2) A part of the colored liquid cured product 12 is embedded in the undercoat layer 14, and
(3) An undercoat layer 14 exists between the lower side of the colored liquid cured product 12 and the substrate 16.
That is, the printed matter obtained by applying the coloring liquid onto the semi-cured undercoat liquid layer has a cross section as schematically shown in FIG. When the above conditions (1), (2), and (3) are satisfied, it can be said that the colored liquid is applied to the semi-cured undercoat liquid. In this case, the liquid droplets of the colored liquid ejected with high density are connected to each other to form a colored film, which gives a uniform and high color density. The undercoat layer means a layer obtained by curing the undercoat liquid layer.

3 and 4 are schematic cross-sectional views showing one embodiment of a printed matter obtained by depositing a colored liquid onto an uncured undercoat liquid layer. 3 and 4 show the undercoat layer 18 in which a colored liquid is applied to the uncured undercoat liquid layer.
When the colored liquid is ejected onto the uncured undercoat liquid layer, all of the colored liquid enters the undercoat liquid layer and / or the undercoat liquid does not exist below the colored liquid. Specifically, in FIG. 3, in the cross section of the image 10 to be obtained, the colored liquid cured product 12 is completely submerged in the undercoat layer 18, and a part of the colored liquid cured product 12 does not appear on the surface. . Further, as shown in FIG. 4, in the cross section of the obtained image 10, the undercoat layer 18 does not exist below the colored liquid cured product 12.
In this case, even if the coloring liquid is applied at a high density, the droplets are independent of each other, which causes a decrease in color density.

FIG. 5 is a schematic cross-sectional view showing one embodiment of a printed matter obtained by depositing a colored liquid onto a completely cured undercoat liquid layer. FIG. 5 shows the undercoat layer 20 in which a colored liquid is applied to the fully cured undercoat liquid layer.
When the colored liquid is ejected onto the completely cured undercoat liquid layer, the colored liquid does not enter the undercoat liquid layer. Specifically, as shown in FIG. 5, the colored liquid cured product 12 does not sink into the undercoat layer 20.
Such a state causes the occurrence of droplet ejection interference, a uniform colored liquid film layer cannot be formed, and the color reproducibility is lowered.

From the viewpoint of forming a uniform colored liquid liquid layer (colored film) and preventing the occurrence of droplet ejection interference without the liquid droplets becoming independent when the colored liquid droplets are applied at high density, The transfer amount of the undercoat liquid per unit area is preferably sufficiently smaller than the maximum droplet amount of the coloring liquid applied per unit area. That is, when the transfer amount (weight) per unit area of the undercoat liquid layer is M (undercoat liquid) and the maximum weight of the colored liquid applied per unit area is m (colored liquid), M (undercoat liquid), m The (coloring liquid) preferably satisfies the following relationship.
[M (colored liquid) / 30] ≦ [M (undercoat liquid)] ≦ [m (colored liquid)]
Further, it is more preferable that [m (colored liquid) / 10] ≦ [M (undercoat liquid)] ≦ [m (colored liquid) / 3], and [m (colored liquid) / 10] ≦ [M (undercoat). Liquid)] ≦ [m (colored liquid) / 5]. Here, the maximum weight of the coloring liquid applied per unit area is the maximum weight per color.
It is preferable that [m (colored liquid) / 30] ≦ [M (undercoat liquid)] because the occurrence of droplet ejection interference can be suppressed and the dot size reproducibility is excellent. Further, it is preferable that M (undercoat liquid) ≦ m (colored liquid) because a uniform colored liquid layer can be formed and an image having a high density can be obtained.

The transfer amount of the undercoat liquid layer per unit area was determined by the transfer test described below. After the completion of the semi-curing process (for example, after irradiation of active energy rays) and before droplets of colored liquid are ejected, a penetrating medium such as plain paper is pressed against the semi-cured undercoat liquid layer, It is defined by measuring the amount of the undercoat liquid transferred to the permeation medium.
For example, when the maximum discharge amount of the colored liquid is 600 × 600 dpi and the droplet ejection density is 12 picoliters per pixel (dot), the maximum weight m (colored liquid) of the colored liquid applied per unit area is 0.74 mg / cm ² (here, the density of the colored liquid is assumed to be about 1.1 g / cm ³ ). Therefore, amount of undercoat liquid layer transferred is preferably a unit area is per 0.025 mg / cm ² or more 0.74 mg / cm ² or less, more preferably 0.037 mg / cm ² or more 0.25 mg / cm ² or less More preferably, it is 0.074 mg / cm ² or more and 0.148 mg / cm ² or less.

When forming a secondary color with the coloring liquid A and the coloring liquid B, it is preferable to apply the coloring liquid B on the semi-cured coloring liquid A.
FIG. 6 is a schematic cross-sectional view showing one embodiment of a printed material obtained by ejecting the colored liquid B onto the semi-cured colored liquid A. FIG. FIG. 6 shows a colored liquid A cured product 24 and a colored liquid B cured product 22 obtained by applying the colored liquid B to the semi-cured colored liquid A.
When the colored liquid B is ejected onto the semi-cured colored liquid A, a part of the colored liquid B enters the colored liquid A, and the colored liquid A exists below the colored liquid B. . That is, the printed matter obtained by applying the coloring liquid B onto the semi-cured coloring liquid A has a part of the coloring liquid B cured product 22 on the surface as shown in FIG. Part of the colored liquid B cured product 22 is embedded in the colored liquid A cured product 24. Further, a colored liquid A cured product is present below the colored liquid B cured product 22. Colored liquid A cured film (colored film A, colored liquid A cured product 24 in FIG. 6) and colored liquid B cured film (colored film B, colored liquid B cured product 22 in FIG. 6) are laminated. Good color reproduction is possible.

7 and 8 are schematic cross-sectional views showing one embodiment of a printed matter obtained by depositing the colored liquid B on the uncured colored liquid A. FIG. FIG. 7 shows a colored liquid A cured product 26 and a colored liquid B cured product 22 obtained by applying the colored liquid B to the uncured colored liquid A.
When the colored liquid B is ejected onto the uncured colored liquid A, all of the colored liquid B sinks into the colored liquid A and / or the colored liquid A is not present below the colored liquid B. Become. That is, when a cross-sectional view of the obtained image is observed, as shown in FIG. 7, the entire colored liquid B cured product 22 is embedded in the colored liquid A cured product 26 and / or as shown in FIG. The colored liquid A cured product 26 does not exist in the lower layer of the colored liquid B cured product 22. In this case, even if the droplets of the colored liquid B are applied at a high density, the droplets are independent from each other, which causes a decrease in the saturation of the secondary color.

  FIG. 9 is a schematic cross-sectional view showing an embodiment of a printed matter obtained by ejecting the colored liquid B onto the completely cured colored liquid A. FIG. In FIG. 9, a colored liquid A cured product 28 and a colored liquid B cured product 22 obtained by adding the colored liquid B to the fully cured colored liquid A are shown. When the colored liquid B is ejected onto the completely cured colored liquid A, the colored liquid B will not enter the colored liquid A. As shown in FIG. 9, in the cross-sectional view of the obtained image, the colored liquid B cured product 22 does not sink into the colored liquid A cured product 28. Such a state causes the occurrence of droplet ejection interference, a uniform colored liquid film layer cannot be formed, and the color reproducibility is lowered.

From the viewpoint of forming a uniform colored liquid B liquid layer and suppressing the occurrence of droplet ejection interference, the unit area does not become independent when the colored liquid B liquid droplets are applied at high density. The transfer amount of the colored liquid A per hit is preferably sufficiently smaller than the maximum droplet amount of the colored liquid B applied per unit area. That is, when the transfer amount (weight) per unit area of the colored liquid A layer is M (colored liquid A) and the maximum weight of the colored liquid B discharged per unit area is m (colored liquid B), M (colored) Liquid A) and m (colored liquid B) preferably satisfy the following relationship.
[M (colored liquid B) / 30] ≦ [M (colored liquid A)] ≦ [m (colored liquid B)]
Further, it is more preferable that [m (colored liquid B) / 20] ≦ [M (colored liquid A)] ≦ [m (colored liquid B) / 3], and [m (colored liquid B) / 10] ≦. It is more preferable that [M (colored liquid A)] ≦ [m (colored liquid B) / 5].
It is preferable that [m (colored liquid B) / 30] ≦ [M (colored liquid A)] because the occurrence of droplet ejection interference can be suppressed and the dot size reproducibility is excellent. Further, [M (colored liquid A)] ≦ [m (colored liquid B)] is preferable because a uniform colored liquid layer can be formed and an image having a high density can be obtained.

Incidentally, the transfer amount (weight) of the colored liquid A per unit area is determined by the transfer test described below. After completion of the semi-curing process (for example, after irradiation with active energy rays) and before droplets of the colored liquid B are ejected, a penetrating medium such as plain paper is pressed against the semi-cured colored liquid A layer. The weight of the colored liquid A transferred to the permeation medium is defined by weight measurement.
For example, if the maximum discharge amount of the coloring liquid B is 12 picoliters per pixel at a droplet ejection density of 600 × 600 dpi, the maximum weight m (coloring liquid) of the coloring liquid B discharged per unit area is 0.74 mg / cm ² (here, the density of the colored liquid B is assumed to be about 1.1 g / cm ³ ). Thus, pigmented transfer amount of liquid A layer is preferably a unit area is per 0.025 mg / cm ² or more 0.74 mg / cm ² or less, more preferably 0.037 mg / cm ² or more 0.25 mg / cm ² Or less, more preferably 0.074 mg / cm ² or more and 0.148 mg / cm ² or less.

  In the case of a curing reaction based on an ethylenically unsaturated compound or a cyclic ether, the unpolymerization rate can be quantitatively measured by the reaction rate of an ethylenically unsaturated group or a cyclic ether group (described later).

  In the case where the semi-cured state of the undercoat liquid and / or the colored liquid is realized by a polymerization reaction of a polymerizable compound that starts polymerization by irradiation with active energy rays or heating, from the viewpoint of improving the scratching property of the printed matter, the unpolymerized rate (A (after polymerization) / A (before polymerization)) is preferably 0.2 or more and 0.9 or less, more preferably 0.3 or more and 0.9 or less, and 0.5 or more and 0.0 or less. Particularly preferably, it is 9 or less.

Here, A (after polymerization) is the absorbance of the infrared absorption peak due to the polymerizable group after the polymerization reaction, and A (before polymerization) is the absorbance of the infrared absorption peak due to the polymerizable group before the polymerization reaction. . For example, when the polymerizable compound contained in the undercoat liquid and / or the coloring liquid is an acrylate monomer or a methacrylate monomer, an absorption peak based on a polymerizable group (acrylate group, methacrylate group) can be observed in the vicinity of 810 cm ^−1. The unpolymerization rate is preferably defined by the absorbance of the peak. When the polymerizable compound is an oxetane compound, an absorption peak based on a polymerizable group (oxetane ring) can be observed in the vicinity of 986 cm ⁻¹ , and the unpolymerization rate is preferably defined by the absorbance of the peak. When the polymerizable compound is an epoxy compound, an absorption peak based on a polymerizable group (epoxy group) can be observed in the vicinity of 750 cm ⁻¹ , and the unpolymerization rate is preferably defined by the absorbance of the peak.

  Moreover, as a means for measuring an infrared absorption spectrum, a commercially available infrared spectrophotometer can be used, which may be either a transmission type or a reflection type, and is preferably selected as appropriate in the form of a sample. For example, it can be measured using an infrared spectrophotometer FTS-6000 manufactured by BIO-RAD.

<The process of providing a coloring liquid on a recording medium>
In the present invention, the colored liquid that is discharged onto the semi-cured undercoat liquid and / or the colored liquid film may be ejected with a droplet size of 0.1 pL or more and 100 pL or less (preferably by an inkjet nozzle). preferable. When the droplet size is within the above range, it is effective in that an image with high sharpness can be drawn at a high density. More preferably, it is 0.5 pL or more and 50 pL or less.
After applying the undercoat liquid, the droplet ejection interval until the colored liquid droplets are ejected is preferably in the range of 5 μs or more and 10 seconds or less. When the droplet ejection interval is within the above range, it is effective in that the effect of the present invention can be remarkably exhibited. The droplet ejection interval of the colored liquid droplets is more preferably 10 μs to 5 seconds, and particularly preferably 20 μs to 5 seconds.

  As means for applying the coloring liquid, it is preferable to use an ink jet head. As an inkjet head, for example, a charge control method that ejects ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezo element, an electric signal is converted into an acoustic beam, and ink is used. A head such as an acoustic ink jet method in which ink is ejected by using radiation pressure by irradiating the ink, and a thermal ink jet (bubble jet (registered trademark)) method in which ink is heated to form bubbles and the generated pressure is used. Is preferred.

<Step of completely curing the image>
The “complete curing” in the present invention refers to a state in which the inside and the surface of the undercoat liquid and the coloring liquid are completely cured. Specifically, after the completion of the complete curing process (for example, after irradiation with active energy rays or after heating), whether the surface of the undercoat liquid or colored liquid was transferred to the permeation medium by pressing the permeation medium such as plain paper. It can be judged depending on why. That is, the case where no transfer is performed is called a completely cured state.
As a curing means for completely curing the image, a light source for irradiating active energy rays, a heater such as an electric heater or an oven, and the like can be selected according to the purpose.
As the active energy ray, in addition to ultraviolet rays, for example, visible light, α ray, γ ray, X ray, electron beam and the like can be used. Of these, the active energy rays are preferably electron beams, ultraviolet rays and visible rays, and ultraviolet rays are particularly preferred from the viewpoint of cost and safety.
Full amount of energy required for the curing reaction, the composition, in particular depends on the type and content of the polymerization initiator, generally on the order 100 mJ / cm ² or more 10,000 / cm ² or less.
Suitable devices for irradiating active energy rays include metal halide lamps, mercury lamps, LED light sources, and the like.

In addition, when energy is applied by the heating, a device that generates heat can be used as the heating means. In this case, it is preferable that the base material to which the undercoat liquid and the coloring liquid are applied is heated for 0.5 seconds to 10 seconds under the condition that the surface temperature of the base material is in a temperature range of 50 ° C. or higher and 100 ° C. or lower. .
In the case of heating, a curing reaction due to polymerization or crosslinking of the polymerizable compound is promoted by the temperature rise, and the shape formed by the collision of the droplets becomes stronger. This is preferable because a strong image can be obtained.
Heating can be performed using a non-contact type heating means, and a heating device that passes through a heating furnace such as an oven, or a heating device that exposes the entire surface of ultraviolet light, visible light, infrared light, or the like is suitable. It is.
Examples of light sources suitable for exposure as the heating means include metal halide lamps, xenon lamps, tungsten lamps, carbon arc lamps, mercury lamps, and the like.

In FIG. 1, four color liquids of yellow, cyan, magenta, and black are used. However, the present invention is not limited to this, and a white color liquid can also be used. The order of the colored liquids to be ejected is not particularly limited, but it is preferable to apply the colored liquid with low brightness to the recording medium. When four colors of yellow, cyan, magenta, and black are used, yellow It is preferable to apply on the recording medium in the order of cyan → magenta → black. Further, in the case of using a coloring liquid of five colors obtained by adding white to this, it is preferable to apply the coloring liquid in the order of white → yellow → cyan → magenta → black.
At least one colorant may be used, but in order to obtain a full-color image, four colorants of yellow, cyan, magenta and black or five colorants of yellow, cyan, magenta, black and white are used. It is preferable to do. Furthermore, the present invention is not limited to this, and eight colored liquids of cyan, light cyan, magenta, light magenta, gray, black, white, and yellow can be used.

In the present invention, the ink jet recording method is not limited to the above ink jet recording method, and the ink set for ink jet recording of the present invention can also be used for other ink jet recording methods.
That is, after forming an image with a colored liquid, a method known to those skilled in the art can be appropriately selected, such as discharging or applying an undercoat liquid as an overcoat layer.

<Recording medium>
In the present invention, the material used for the recording medium is not particularly limited, and any material may be used. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the above-mentioned metal is laminated or deposited. A preferable support includes a polyester film and an aluminum plate.
In the present invention, a non-absorbable recording medium is preferably used as the recording medium. In the ink jet recording method, by applying a coloring liquid after applying an undercoat liquid, high-definition is achieved with respect to various non-absorbing recording media that have heretofore been difficult to form a fine image by droplet ejection interference. An image can be formed.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these.
(Preparation of pigment dispersion)
The components shown in Table 1 were mixed and stirred with a stirrer for 1 hour. The mixture after stirring was dispersed by bead mill dispersion to obtain a pigment dispersion. Dispersion conditions were such that zirconia beads having a diameter of 0.65 mm were filled at a filling rate of 70%, the peripheral speed was 9 m / s, and the dispersion time was 2 to 4 hours.
Table 1 shows the composition of the pigment dispersion.

Cyan pigment A: PB15: 3 (IRGALITE BLUE GLO; manufactured by Ciba Specialty Chemicals)
Magenta pigment A: PV19 (CINQUASIA MAGENTA RT-355D; manufactured by Ciba Specialty Chemicals)
Yellow pigment A: PY120 (NOVOPERM YELLOW H2G; manufactured by Clariant)
Carbon black: SPECIAL BLACK 250 (Degussa)
Titanium dioxide: CR60-2 (Ishihara Sangyo Co., Ltd.)
Dispersant A: BYK-168 (by Big Chemie)
Dispersant B: Solsperse 36000 (Noveon)
Polymerizable compound A: PEA (phenoxyethyl acrylate; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

(Preparation of liquid composition)
Tables 2 to 6 show the compositions of ink sets 1 to 5, respectively.
The components shown in Table 2 (unit: grams) were stirred, mixed and dissolved to obtain a liquid composition. In addition, when the surface tension of these liquid compositions was measured at a liquid temperature of 25 ° C. by the Wilhelmy method using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., surface tension meter CBVP-Z, etc.) The surface tension of the colored liquid was also in the range of 23 to 25 mN / m. On the other hand, the surface tension of the undercoat liquid was in the range of 20 to 22 mN / m.

Polymerizable compound A: PEA (phenoxyethyl acrylate; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Polymerizable compound B: DPGDA (dipropylene glycol diacrylate; manufactured by Daicel Cytec Co., Ltd.)
Polymerizable compound C: A-TMPT (trimethylolpropane triacrylate; manufactured by Shin-Nakamura Chemical Co., Ltd.)
Surfactant A: BYK-307 (manufactured by Big Chemie, surfactant)
Polymerization inhibitor A: FIRSTCURE ST-1 (manufactured by Albemarle)
Initiator A: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (acylphosphine oxides)
Initiator B: Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (acylphosphine oxides)
Initiator C: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one Sensitizer A: Formula A
Sensitizer B: Chemical formula B below
Sensitizer C: Chemical formula C below
Sensitizer D: Chemical formula D below
In the chemical formula below, Et represents an ethyl group.

(Image recording device)
The prepared colored liquids for five colors (M1 to M6, C1 to C6, Y1 to Y6, Bk1 to Bk6, W1 to W6) are ink jet printers (head mounted by Toshiba Tec Corporation = droplet ejection frequency: 6.2 kHz, nozzles) Number: 636, Nozzle density: 300 npi (nozzle / inch, the same applies below), Drop size: 5 sets of headsets with 6 lines to 42 pl arranged in 7 stages and 600 npi with a full line array Loaded).
The head was fixed to the machine in the order of white, yellow, cyan, magenta, and black from the upstream side in the recording medium conveyance direction, and an undercoat liquid roll coater and a semi-curing light source were further installed upstream of the white ink head. Here, as the undercoat liquid, undercoat liquids (U1 to U6) were used.
The recording medium can be moved directly under the head, and each of the white, yellow, cyan, and magenta heads loaded with colored liquids (M1 to M6, C1 to C6, Y1 to Y6, and W1 to W6) is provided. On the other hand, a pinning light source (semi-curing light source) was arranged in the traveling direction of the recording medium, and five metal halide lamps (light intensity 3,000 mW / cm ² ) were installed downstream of the black ink head.
An LED light source was used as the semi-curing light source and the pinning light source. As the LED, NCCU033 manufactured by Nichia Corporation was used. This LED outputs ultraviolet light having a wavelength of 340 nm or more and 400 nm or less centered on a wavelength of 365 nm from one chip, and when a current of about 500 mA is applied, light of about 100 mW is emitted from the chip. A plurality of these were arranged at intervals of 7 mm, and the current and the distance between the light source and the recording medium were adjusted so that the exposure intensity on the surface of the recording medium was about 100 mW / cm ² .
The irradiation energy by the metal halide lamp can be adjusted from 300 to 1,500 mJ / cm ² depending on the number of metal halide lamps to be lit. Specifically, 300 mJ / cm ² (1 unit lighting), 600 mJ / cm ² (2 units lighting), 900 mJ / cm ² (3 units lighting), 1,200 mJ / cm ² (4 units lighting), 1,500 mJ / Cm ² (5 units lit).
The recording medium was conveyed by roll conveyance, and an image of 600 dpi × 600 dpi was formed on the recording medium. The recording medium used here was plastic film A (made of white polyethylene) and plastic film B (made of transparent polyethylene).

Example 1
Using the image recording apparatus, images were formed on plastic film A (made of white polyethylene) and plastic film B (made of transparent polyethylene) by the procedure described below to obtain a printed matter.
The printing procedure is as follows (1) to (12).
(1) The undercoat liquid (U1) was uniformly applied to a thickness of 5 μm by a roll coater (application speed: 400 mm / s).
(2) After applying the undercoat liquid (U1), exposure was performed with a light source for semi-curing (light intensity 100 mW / cm ² ), and the applied undercoat liquid (U1) was in a semi-cured state.
(3) A white color liquid (W1) was applied to the recording medium to which the undercoat liquid was applied by a white head to form a white image.
(4) Exposure was performed with a light source for pinning (light intensity 100 mW / cm ² ), and the white liquid was brought into a semi-cured state.
(5) A yellow coloring liquid (Y1) was applied on the recording medium by a yellow head to form a yellow image.
(6) Exposure was performed with a light source for pinning (light intensity 100 mW / cm ² ), and the yellow coloring liquid was made into a semi-cured state.

(7) A cyan color liquid (C1) was applied on the recording medium by a cyan head to form a cyan image.
(8) Exposure was performed with a light source for pinning (light intensity 100 mW / cm ² ), and the cyan coloring liquid was in a semi-cured state.
(9) A magenta coloring liquid (M1) was applied on the recording medium by a magenta head to form a magenta image.
(10) Exposure was performed with a light source for pinning (light intensity 100 mW / cm ² ), and the magenta coloring liquid was made into a semi-cured state.
(11) A black color liquid (Bk1) was applied to the recording medium by a black head to form a black image.
(12) Exposure was performed with a metal halide lamp (light intensity 3,000 mW / cm ² ), and the image was completely cured. The exposure energy was adjusted to 300 to 1,500 mJ / cm ² depending on the number of metal halide lamps to be lit.

  Here, the conveyance speed of the non-recording medium was 400 mm / s, and the amount of the colored liquid per dot was about 12 picoliters. When forming an image of a tertiary color (for example, cyan, magenta, and yellow), (3), (4), (10), and (11) were omitted in the above procedure. Further, when forming an image of a secondary color (for example, cyan and magenta), (3) to (6), (10), and (11) were omitted in the above procedure. When forming an image of a primary color (for example, yellow), (3), (4), and (6) to (11) were omitted in the above procedure. When the plastic film A was used, the white ink application process ((3), (4)) was omitted.

(Example 2, Comparative Examples 1 and 2)
As described in Table 8, a recorded matter (image) was produced in the same manner as in Example 1 except that the coloring liquid and the undercoat liquid were replaced.

<Measurement and evaluation of transfer amount>
In any of Examples 1 to 3 and Comparative Examples 1 to 3, the maximum amount of coloring liquid applied per unit area (3), (5), (7), (9), and (11) ( weight) was in the range of 0.74mg / cm ² ~0.87mg / cm ² each color colored liquid.

In any of Examples 1 to 3 and Comparative Examples 1 to 3, exposure and pinning with a semi-curing light source in steps (2), (4), (6), (7), (8), and (10) withdrawn samples after exposure to use a light source was measured for the weight of the undercoat liquid to be transferred by the transfer test, there within from 0.10 mg / cm ² of 0.12 mg / cm ² after any step It was.

Therefore, the relationship between the transfer amount (weight) M (undercoat liquid) per unit area of the undercoat liquid layer and the maximum weight m (colored liquid) of the colored liquid discharged per unit area is
m (colored liquid) / 10 <M (undercoat liquid) <m (colored liquid) / 5
Was met.

In any of Examples 1 to 3 and Comparative Examples 1 to 2, exposure and pinning with a semi-curing light source in steps (2), (4), (6), (7), (8), and (10) withdrawn samples after exposure to use a light source was measured for the weight of the undercoat liquid to be transferred by the transfer test, there within from 0.10 mg / cm ² of 0.12 mg / cm ² after any step It was.
Therefore, the relationship between the transfer amount (weight) M (undercoat liquid) per unit area of the undercoat liquid layer and the maximum weight m (colored liquid) of the colored liquid discharged per unit area is
m (colored liquid) / 10 <M (undercoat liquid) <m (colored liquid) / 5
Was met.

On the other hand, the sample was prepared after the exposure with the semi-curing light source and the exposure with the pinning light source in the steps (2), (4), (6), (7), (8), and (10) of Comparative Example 3. extraction was measured the weight of the undercoat liquid transferred by the transfer test was in the range of 0.40 mg / cm ² of 0.60 mg / cm ² even after any step.
Therefore, the relationship between the transfer amount (weight) M (undercoat liquid) per unit area of the undercoat liquid layer and the maximum weight m (colored liquid) of the colored liquid discharged per unit area is
m (colored liquid) / 10 <M (undercoat liquid) <m (colored liquid) / 5
Did not meet.
Transfer amount of white coloring liquid after exposure to light source for pinning in step (4) in Examples 1 and 2 and Comparative Examples 1 and 2; transfer amount of yellow color liquid after exposure to light source for pinning in step (6); The transfer amount of the cyan coloring liquid after exposure to the light source for pinning in 8) and the transfer amount of the magenta coloring liquid after exposure to the light source for pinning in the step (10) were extracted after each step and measured by a transfer test. For any of the colored liquids, the transfer amount per unit area was in the range of 0.10 mg / cm ² to 0.12 mg / cm ² .
Therefore, in a combination of colored liquids having different hues, the weight M (colored liquid A) of the uncured portion of the colored liquid A previously applied onto the recording medium and the unit area of the colored liquid B applied later. The relationship of maximum weight m (colored liquid B) per hit is
m (colored liquid B) / 10 <M (colored liquid A) <m (colored liquid B) / 5
Was met.

On the other hand, the transfer amount of the white color liquid after the exposure to the light source for pinning in the step (4) in Example 3 and the comparative example 3, the transfer amount of the yellow color liquid after the exposure to the light source for pinning in the step (6), step (8). The transfer amount of the cyan coloring liquid after exposure to the light source for pinning in Step 1, and the transfer amount of the magenta coloring liquid after exposure to the light source for pinning in Step (10) were measured by a transfer test after extracting the sample. Transfer amount per unit area with respect to any of the colored liquid was in the range of 0.40 mg / cm ² of 0.60 mg / cm ^2.
Therefore, in a combination of colored liquids having different hues, the weight M (colored liquid A) of the uncured portion of the colored liquid A previously applied onto the recording medium and the unit area of the colored liquid B applied later. The relationship of maximum weight m (colored liquid B) per hit is
m (colored liquid B) / 10 <M (colored liquid A) <m (colored liquid B) / 5
Did not meet.

The transfer test was conducted using plain paper (Fuji Xerox Co., Ltd., copy paper C2, product code V436) as the non-penetrable medium. The plain paper was pressed with a uniform force (500 to 1000 mN / cm ² ) against the semi-cured undercoat liquid or semi-cured colored liquid on the recording medium that had been extracted, and allowed to stand for about 1 minute. Thereafter, the plain paper was gently peeled off, the weight of the plain paper before and after the transfer test was measured, and the result was obtained by dividing by the area where the undercoat or colored liquid was formed.

<Evaluation items>
[Curing property test]
Curability was defined by the exposure energy at which the surface was not sticky after printing.
As for the presence or absence of stickiness on the surface after printing, plain paper (copy paper C2 manufactured by Fuji Xerox Co., Ltd.) is pressed immediately after printing. It was judged that there was nothing.
Exposure ^{energy, 300mJ / cm 2, 600mJ /} cm 2, 900mJ / cm 2, 1,200mJ / cm 2, is changed from 1,500 mJ / cm ^2, it was evaluated according to the following criteria.

In addition, sclerosis | hardenability was evaluated using the printed matter A (FIG. 10 (a)). In FIG. 10A, 400 is a solid print portion formed with primary colors (cyan, magenta, yellow, black, or white), and is colored at 12 picoliters per pixel at a pixel density of 600 × 600 dpi. Liquid droplets were applied to print a primary color solid image. Reference numeral 401 denotes a portion to which no coloring liquid is applied. The coloring liquid is not applied and the undercoat liquid is exposed on the surface. When color ink (cyan, magenta, yellow) and black ink are used, an image is formed on plastic film A (made of white polyethylene), and when white ink is used, it is placed on plastic film B (made of transparent polyethylene). An image was formed.
5: Stickiness disappeared after exposure at 300 mJ / cm ² .
4: Stickiness disappeared after exposure at 600 mJ / cm ² .
3: No stickiness after exposure at 900 mJ / cm ² .
2: No stickiness after exposure at 1,200 mJ / cm ² .
1: Stickiness disappeared after exposure at 1,500 mJ / cm ² .

Table 8 shows the results of the curability test. Here, the lower tack-free sensitivity is preferable from the viewpoint of curability, and particularly preferably 1,000 mJ / cm ² or less (5 to 3).

[Blocking test]
When the printed surface and the substrate surface were overlapped and peeled off after a certain time, the presence or absence of tearing of the film on the printed surface or transfer to the substrate surface was evaluated.
The printed materials used for the blocking test were all exposed with an exposure energy of 1,000 mJ / cm ² . In addition, the printed matter was stored at room temperature for 24 hours in which the printed surface and the substrate surface were superimposed and a uniform load (1 kg / cm ² ) was applied to the entire printed matter by weight. After 24 hours, the printed surface and the substrate surface were peeled off, and evaluated visually according to the following criteria.

  The results of the blocking test are shown in Table 8. Here, it is preferable from the viewpoint of curability that the printed surface is not torn or transferred to the substrate surface. In particular, only 3 is acceptable in the above criteria.

[Color reproducibility evaluation test]
Using the image recording apparatus, the color reproducibility (color reproduction maximum range) of each ink set was determined according to the following criteria by determining the coverage of pantone color sample book data (PANTON FORMULA GUIDED SOLID COATED). The print image data is color patch data of all 950 colors allocated uniformly. Here, chromaticity (a ^* , b ^* ) was measured with SPM100-II manufactured by Gretag.

As an evaluation image, a color patch image printed on a plastic film A (made of white polyethylene) was used.
5: Inclusion rate 90%
4: Inclusion rate 80% or more and less than 90% 3: Inclusion rate 70% or more and less than 80% 2: Inclusion rate 60% or more and less than 70% 1: Inclusion rate less than 60%

  Table 8 shows the results of the color reproducibility evaluation test. Here, it is preferable that the color reproduction maximum range is wide. In the above criteria, the coverage is within an allowable range of 60% or more (5-2), and particularly preferably 80% or more (5, 4).

In the case of an ink set to which a sensitizer having a polymerizable group (sensitizers A and B) is added (Examples 1, 2 and 3), even with an exposure energy of 300 to 600 mJ / cm ² showing excellent curability. There was no stickiness and there was no problem in the blocking test.
On the other hand, in the case of an ink set to which a sensitizer having no polymerizable group (sensitizers C and D) was added (Comparative Examples 1 and 2), the curability was within an acceptable range, but the blocking test The film was broken and transferred to the substrate. It is suggested that blocking is likely to occur because the ratio of the non-curable component in the ink is increased.

When an ink set containing no sensitizer was used (Comparative Example 3), the curability and the blocking test were acceptable, but the color reproducibility was remarkably lowered. The undercoating liquid and the coloring liquid could not form a preferable semi-cured state, and a decrease in density was observed for both the primary color and the secondary color, resulting in a narrow color reproduction range.
However, when a sensitizer is added only to the undercoat liquid (Example 3), the undercoat liquid can form a preferred semi-cured state even if the colored liquid cannot form a preferred semi-cured state, and the primary color. There was no decrease in the concentration of. However, since the secondary color density was reduced, the color reproduction range was narrow, but it was within the allowable range.

It is an example of the conceptual diagram of the inkjet recording device which can be used suitably for this invention. It is a cross-sectional schematic diagram which shows one embodiment of the printed matter obtained by droplet-dropping a colored liquid on the semi-hardened undercoat liquid layer. It is a cross-sectional schematic diagram which shows one embodiment of the printed matter obtained by droplet-dropping a colored liquid on the uncured undercoat liquid layer. It is a cross-sectional schematic diagram which shows another embodiment of the printed matter obtained by depositing a coloring liquid on the uncured undercoat liquid layer. It is a cross-sectional schematic diagram which shows one embodiment of the printed matter obtained by depositing a coloring liquid on the undercoat liquid layer of a completely hardened state. It is a cross-sectional schematic diagram which shows one embodiment of the printed matter obtained by depositing the coloring liquid B on the semi-cured coloring liquid A. It is a cross-sectional schematic diagram which shows one embodiment of the printed matter obtained by ejecting the coloring liquid B on the uncured coloring liquid A. It is a cross-sectional schematic diagram which shows other one Embodiment of the printed matter obtained by droplet-dropping the coloring liquid B on the uncured coloring liquid A. It is a cross-sectional schematic diagram which shows one embodiment of the printed matter obtained by depositing the coloring liquid B on the coloring liquid A in a completely cured state. It is a conceptual schematic diagram which shows the image formed in the Example.

Explanation of symbols

1 Means for applying undercoat liquid 2 Means for semi-curing undercoat liquid 3Y, 3C, 3M, 4K Means for applying colored liquid 4Y, 4C, 4M, 4K Means for semi-curing colored liquid 5 Means for completely curing image 6 Recording medium 7A, 7B Recording medium conveying means 10 Image 12 Colored liquid cured product 14 Undercoat layer 16 in which colored liquid is applied to semi-cured undercoat liquid layer Base material 18 Colored liquid in uncured undercoat liquid layer The undercoat layer 20 to which the colored liquid is applied to the completely cured undercoat liquid layer 22 The colored liquid B cured product 24 The colored liquid obtained by adding the colored liquid B to the semi-cured colored liquid A A cured product 26 Colored solution A cured product 28 obtained by applying colored solution B to uncured colored solution A Colored solution A cured product obtained by applying colored solution B to completely cured colored solution A 400 Solid with primary color Portion not granted field 401 colored liquid (undercoat liquid is exposed on the surface)
402 Solid or secondary color solid print portion 403 A portion to which no coloring liquid is applied (the undercoat liquid comes out on the surface)
404 Solid or secondary color solid print part 405 Black character part

Claims (11)

Radically polymerizable compounds,
A photopolymerization initiator, and
An undercoat liquid comprising a sensitizer represented by formula (I) or (II).

In the formula (I), X represents O, S, or NR ^a . n1 represents 0 or 1.
R ^a , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ each independently represent a hydrogen atom or a monovalent substituent, Of these, at least one contains an ethylenically unsaturated double bond.
In formula (II), X represents O, S or NR ^b . n2 represents 0 or 1.
R ^b , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ each independently represent a hydrogen atom or a monovalent substituent, and at least one of these One contains an ethylenically unsaturated double bond.
In the formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ may be bonded to each other to form a ring. In II), R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be linked together to form a ring.   The undercoat liquid according to claim 1, wherein the undercoat liquid contains at least one compound selected from the group consisting of an acylphosphine oxide compound and an α-aminoacetophenone compound as a photopolymerization initiator.   The undercoat liquid according to claim 1 or 2, wherein the undercoat liquid contains a surfactant.   An ink set for inkjet recording, comprising at least the undercoat liquid according to any one of claims 1 to 3, and a coloring liquid containing at least a radical polymerizable compound, a photopolymerization initiator, and a coloring agent.   The ink set for inkjet recording according to claim 4, wherein the coloring liquid contains a sensitizer represented by the formula (I) or (II).   The ink set for inkjet recording according to claim 4 or 5, wherein the colored liquid contains at least one compound selected from the group consisting of an acylphosphine oxide compound and an α-aminoacetophenone compound as a photopolymerization initiator.   The ink set for inkjet recording according to any one of claims 4 to 6, wherein the surface tension γA of the coloring liquid and the surface tension γB of the undercoat liquid satisfy γA> γB. In the ink jet recording method using the ink set for ink jet recording according to any one of claims 4 to 7,
Applying an undercoat liquid onto the recording medium;
Semi-curing the undercoat liquid;
Forming an image by discharging a colored liquid onto the semi-cured undercoat liquid.   In the ink jet recording method using the ink set for ink jet recording according to any one of claims 4 to 7, coloring is performed when a secondary color is formed using the coloring liquid A and the coloring liquid B having different hues. An inkjet recording method comprising a step of semi-curing the liquid A and a step of discharging the color liquid B onto the semi-cured color liquid A.   The inkjet recording method according to claim 8 or 9, wherein the step of semi-curing the undercoat liquid and / or the step of semi-curing the coloring liquid A is ultraviolet light irradiation.   The inkjet recording method according to claim 10, wherein the ultraviolet light for semi-curing the undercoat liquid and / or the ultraviolet light for semi-curing the coloring liquid A includes light in a range of at least 340 to 400 nm.

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