JP2009148922A - Ink-jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording method for obtaining a printed matter excellent in image clarity. <P>SOLUTION: In the ink-jet recording method, an ink set equipped with two or more kinds of water-based inks having different compositions is used, at least one ink of the water-based inks contains a water-insoluble organic compound which a maximum weight dissolvable in 100 g water (20°C) is 5 g or less, and a dot by the other ink is struck in piles later on a dot struck previously by the ink. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording method.

The ink jet recording system is a recording system in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle and attaching them to a recording member. This method is widely spread because it is easy to make full color and is inexpensive, and has many advantages such as the ability to use plain paper as a recording member and non-contact with the object to be printed.
Among them, from the viewpoint of weather resistance and water resistance of printed matter, those using pigment-based ink as a colorant have become mainstream. (For example, see Patent Documents 1 to 3)

Patent Document 1 discloses a water-based ink in which a pigment is contained in a vinyl polymer.
Patent Document 2 discloses an aqueous dispersion for ink jet recording containing an aqueous dispersion of vinyl polymer particles or polyester polymer particles containing a colorant (B) and a water-insoluble organic compound (A).
Patent Document 3 discloses an ink set including two or more different color inks, and the ink contains a water-insoluble organic compound (A), polymer particles (B), and a colorant (C). An ink set for inkjet recording is disclosed.
However, the water-based ink containing the above-described pigment dispersion does not describe a printing method for improving image clarity.

International Publication No. 00/39226 Pamphlet JP 2007-77375 A JP 2006-316246 A

  An object of the present invention is to provide an ink jet recording method for obtaining a printed matter having excellent image clarity.

In order to solve the above problems, the present inventors have ejected an ink containing a water-insoluble organic compound from an inkjet nozzle onto a photographic paper, and ink droplets exist as dots, and later from the inkjet nozzle. It has been found that it is necessary for the dots of the ejected ink droplets to overlap.
That is, the present invention is an ink jet recording method using an ink set including two or more types of water-based inks having different compositions, wherein at least one of the water-based inks has a maximum weight that can be dissolved in 100 g of water. Provided is an ink jet recording method comprising a water-insoluble organic compound having a (20 ° C.) of 5 g or less, and the dots of other inks are subsequently superimposed on the dots on which the ink has been previously deposited. .

  According to the present invention, it is possible to give a printed matter with excellent image clarity when printing on photographic paper (dedicated paper).

(Inkjet recording method)
The present invention relates to an ink jet recording method using an ink set comprising two or more water-based inks having different compositions, wherein at least one water-based ink among the inks has a maximum weight (20 The ink-jet recording method comprises a water-insoluble organic compound having a temperature of 5 g or less, and dots of other inks are superimposed on the dots on which the ink has been previously deposited. Hereinafter, the present invention will be described in detail. A water-insoluble organic compound having a maximum weight (20 ° C.) that can be dissolved in 100 g of water of 5 g or less may be simply referred to as “water-insoluble organic compound”.

  In the ink jet recording method of the present invention, the ink containing the water-insoluble organic compound is first ejected from the ink jet nozzle, and ink droplets exist as dots on the photographic paper. In addition, the next ink is ejected from the inkjet nozzles on the dots, and the dots of the ink droplets overlap, so that the ink that was struck later spreads further and the printing surface becomes smoother, thereby improving the image clarity. I think that. This is because the dot surface becomes hydrophobic due to the presence of a water-insoluble organic compound in the ink that has been struck first, and hydrophobic substances such as pigments, polymer particles, and activators that are present in the ink that has been struck later. This is considered to be because the affinity with the site is improved and the wetting and spreading are promoted.

It is sufficient that at least a part of the dot that was struck first and the dot that was struck afterwards overlap, but from the viewpoint of effectively improving image clarity, the area ratio of the dots struck later It is preferable that 50% or more, more preferably 70% or more overlap with the previously hit dots. The diameter of the dot alone by the measurement method described later is preferably about 10 to 50 μm.
Normally, the overlap between dots does not completely match, so the area where the subsequent dots expand is the area where the dots that have been struck first overlap and the dots that have been struck after that have spread independently. The total area with the area (see FIG. 1B). Therefore, it is preferable that the ink of the subsequent dots overlaps the area where the first hit dots are continuously spread, that is, the continuous dot connection, because the area where the subsequent dots spread can be increased. .
In addition, the ink that is struck afterwards may or may not contain a water-insoluble organic compound, but in the case where other inks are further struck on the ink. Also, it is preferable that a water-insoluble organic compound is also present in the ink to be hit later.

The ink set used in the ink jet recording method of the present invention includes two or more inks having different compositions. Here, “different compositions” means that the components and / or contents contained in the ink are different. Specifically, two or more types of inks having different colors, two or more types of inks having different colorant contents in the ink, two or more types of inks having different types of water-insoluble organic compounds, and water-insoluble in the inks One or more types selected from two or more types of inks having different organic compound contents are preferred. In addition, “different color” means that the reflected light is measured at a wavelength of light of D65 / 2 by using a spectral color difference meter SE-2000 of Nippon Denshoku Industries Co., Ltd., excluding clear ink, When displayed in the L ^* a ^* b ^* color system, a ^* (red-green chromaticity) and / or b ^* (yellow-blue chromaticity) are not the same color. Examples of the ink include two or more selected from the group consisting of cyan ink, yellow ink, magenta ink, light cyan ink, dark yellow ink, light magenta ink, black ink (hereinafter referred to as colored ink), and clear ink. . Here, the clear ink is ink that does not substantially contain a colorant.
The ink set is preferably a set comprising a combination of two or more colors selected from these, and is any of a three-color ink set, a four-color ink set, a five-color ink set, a six-color ink set, and a seven-color ink set. May be.
The difference in the content of the colorant means that the difference in the content of the colorant in the ink is preferably 1% by weight or more, more preferably 2% by weight or more. Different types of water-insoluble organic compounds mean that the chemical structure of the water-insoluble organic compounds described later is different, and differences in the contents of water-insoluble organic compounds mean that there is a difference in the content of water-insoluble organic compounds in the ink. Is preferably 0.5% by weight or more, more preferably 1.0% by weight or more.

In the ink jet recording method of the present invention, the water-based ink that is first printed and / or the water-based ink that is repeatedly printed afterward preferably contains polymer particles.
The ink set used in the present invention preferably contains clear ink and colored ink. The clear ink preferably contains polymer particles, and when printed on photographic paper (dedicated paper), the portion between the high print area rate portion and the low print area rate portion, or between the print portion and the non-print portion. It is used to eliminate the difference in dot height, and the image clarity can be improved.

As a specific embodiment in the case where the ink that is applied first is a clear ink and the ink that is applied afterward is a colored ink, the clear ink is preferably an ink containing a water-insoluble organic compound and polymer particles. . The colored ink is preferably an ink containing a colorant and polymer particles, and may be an ink containing polymer particles containing a colorant (hereinafter sometimes referred to as “colorant-containing polymer particles”). Further preferred. The colored ink may contain a water-insoluble organic compound. The polymer particles contained in the clear ink and the colored ink are preferably crosslinked polymer particles.
Here, the ink containing colorant-containing polymer particles refers to an ink in which a solid content of a polymer containing a colorant is dispersed in an aqueous ink.

  As a specific embodiment in the case where the ink that is struck first is a colored ink and the ink that is struck afterward is a clear ink, the colored ink includes a water-insoluble organic compound, a colorant, and polymer particles. It is preferable that the ink contains a water-insoluble organic compound and colorant-containing polymer particles. The clear ink is preferably an ink containing polymer particles. The clear ink may contain a water-insoluble organic compound. The polymer particles contained in the colored ink and clear ink are preferably crosslinked polymer particles.

Both the ink that is applied first and the ink that is applied after overlapping may be colored ink or clear ink. In this case, the colored ink that is applied first is water-insoluble. An ink containing an organic compound, a colorant and polymer particles is preferred, and an ink containing a water-insoluble organic compound and colorant-containing polymer particles is more preferred. The colored ink that is repeatedly applied afterwards is preferably an ink containing a colorant and polymer particles, and more preferably an ink containing colorant-containing polymer particles.
The clear ink hit first is preferably an ink containing a water-insoluble organic compound and polymer particles. The clear ink that is repeatedly applied afterwards is preferably an ink containing polymer particles.
The colored ink and the clear ink that are applied later may contain a water-insoluble organic compound. The polymer particles are preferably crosslinked polymer particles.

  In the present invention, in a more preferred embodiment, the ink that is applied first is a clear ink, and the ink that is applied later is a colored ink. Clear inks usually have less solid content than colored inks, so the effect of expanding dots is small. For this reason, image clarity can be improved more effectively by making the clear ink contain a water-insoluble organic compound and expanding the dots of the ink containing a colorant that is applied later.

In the ink jet recording method of the present invention, it is preferable to print by overlapping dots, and it is preferable that the number of passes is large. Therefore, it is preferable to hit with a plurality of passes such as two passes or four passes rather than hitting with one pass.
From the viewpoint of improving image clarity, it is preferable to use photographic paper (dedicated paper) as the printing paper.

(Water-insoluble organic compound)
In the present invention, since the water-insoluble organic compound is present in the previously hit dot, the dot surface becomes hydrophobic, and the hydrophobic ink such as pigment, polymer particles, and activator existing in the ink hit later. It is considered that the image clarity of the printed matter is improved by improving the affinity with the active substance and the part, promoting the wetting and spreading, and smoothing the printed surface.
Further, when polymer particles are used, at least a part of the water-insoluble organic compound is contained in the polymer particles to improve the flexibility of the polymer particles, and the fusibility between the polymer particles is increased. It is considered that the image clarity of the printed matter is improved by the polymer particles being uniformly diffused on the recording paper and the printing surface becoming smooth.

From the viewpoint of improving image clarity, the water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, and more preferably a molecular weight of 100 to 1,200.
The maximum weight (20 ° C.) of the water-insoluble organic compound that can be dissolved in 100 g of water is 5 g or less, preferably 3 g or less, more preferably 1 g or less, and particularly preferably 0.5 g or less.
The water-insoluble organic compound preferably has a LogP value of 4 to 4 from the viewpoint of improving the image clarity of printed matter when printed on special paper and improving the storage stability of an aqueous dispersion containing the water-insoluble compound. 16, more preferably 5 to 16, particularly preferably 6 to 15.

  Here, “Log P value” means the logarithmic value of 1-octanol / water partition coefficient of water-insoluble organic compounds, and is calculated by the fragment approach by SRC's LOGKOW / KOWWIN Program of KowWin (Syracuse Research Corporation, USA). The KowWin Program methodology is described in the following journal article: Meylan, WM and PH Howard. 1995. Atom / fragment contribution method for using octanol-water partition coefficients. J. Pharm. Sci. .). The fragment approach is based on the chemical structure of the compound and takes into account the number of atoms and the type of chemical bond. The LogP value is a numerical value generally used for relative evaluation of the hydrophilicity / hydrophobicity of an organic compound.

The water-insoluble organic compound is preferably at least one selected from the group consisting of an ester compound, an ether compound, and a sulfonic acid amide compound so that the polymer particle can be easily contained in the polymer particle. Two or more ester or ether compounds (f) and / or one or more ester or ether bonds in the molecule, a carboxy group, a sulfuric acid group, a sulfonic acid group, a phosphonic acid group, a phosphoric acid residue, An ester or ether compound (g) having at least one functional group selected from the group consisting of a carbonyl group, an epoxy group and a hydroxyl group is more preferred. The ester or ether bond of the compound (f) is preferably 2 to 3, and may have an ester bond and an ether bond. The number of ester or ether bonds in the compound (g) is preferably 1 to 3. The number of functional groups is preferably 1 to 3. In addition, a phosphoric acid residue means the remaining phosphoric acid group in which a part of phosphoric acid was esterified.
Among the ester compounds, esters obtained from monovalent carboxylic acids or salts thereof and polyhydric alcohols, polyacids (polycarboxylic acids, phosphoric acids) or esters obtained from salts thereof and monohydric alcohols are preferred, and ether compounds Of these, polyhydric alcohol ethers are preferred. Examples of the salt include alkali metal salts, alkanolamine salts, ammonium salts and the like.

As the monovalent carboxylic acid, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, Linear aliphatic carboxylic acids such as palmitic acid, branched aliphatic carboxylic acids such as pivalic acid, unsaturated aliphatic carboxylic acids such as acrylic acid and methacrylic acid), and aromatic carboxylic acids having 6 to 12 carbon atoms (for example, benzoic acid) Acid) and the like.
Examples of the polyvalent acid include aliphatic carboxylic acids having 2 to 12 carbon atoms such as maleic acid, fumaric acid, itaconic acid, succinic acid, adipic acid and sebacic acid, and 6 to 12 carbon atoms such as phthalic acid and trimellitic acid. Aromatic carboxylic acid, phosphoric acid and the like can be mentioned.
The monohydric alcohol is a linear or branched aliphatic alcohol having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, ethyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol). , Aromatic alcohols having 6 to 12 carbon atoms (for example, phenol) and alkylene oxide compounds thereof.
Examples of the polyhydric alcohol include polyhydric alcohols having 2 to 12 carbon atoms such as ethylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and glycerin, and alkylene oxide compounds thereof. A saturated or unsaturated fatty acid or alcohol can be used.

Specific examples of the water-insoluble organic compound include (1) aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, (3) cycloalkane (ken) carboxylic acid ester, (4) phosphoric acid ester, (5) Oxy acid ester, (6) glycol ester, (7) epoxy ester, (8) sulfonamide, (9) polyester, (10) glyceryl alkyl ether, (11) glyceryl alkyl ester, (12) glycol alkyl ether, etc. Can be mentioned.
Among these, from the viewpoint of improving image clarity, the compounds of (1) to (5), (8) and (10) are preferable, and (1) aliphatic carboxylic acid ester and (2) aromatic carboxylic acid ester. , (3) one or more selected from the group consisting of (3) cycloalkane (ken) carboxylic acid ester and (4) phosphoric acid ester, aliphatic dicarboxylic acid ester, aromatic di- or tricarboxylic acid ester, cyclohexane It is especially preferable that it is 1 or more types chosen from the group which consists of alkane (ken) dicarboxylic acid ester and phosphoric acid di or triester.

  (1) Aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, and (3) cycloalkane (ken) carboxylic acid ester are preferably compounds represented by the following formula (1).

(.R wherein, R ¹ and R ² are each independently a hydrogen atom, or a hydrocarbon group having 1 to 22 carbon atoms, R ³ is showing a divalent hydrocarbon group having 1 to 18 carbon atoms ¹ and R ² may be the same or different, except when R ¹ and R ² are both hydrogen atoms, R ^{1 to} R ³ may have a substituent, and m and n are Each independently represents an average addition mole number of 0 to 30, and AO represents an alkanediyloxy group.)

R ¹ and R ² are preferably a linear or branched alkyl or alkenyl group having 2 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, and 7 carbon atoms from the viewpoint of improving the image clarity of printed matter. -23, preferably an aralkyl group having 7 to 11 carbon atoms, or an aryl group having 6 to 22 carbon atoms, preferably 6 to 10 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group. Butyl group, hexyl group, 2-ethylhexyl group, octyl group, dodecyl group, cetyl group, phenyl group, benzyl group and the like. The same applies to the following equations.
R ³ is preferably a divalent aliphatic hydrocarbon group, a cyclic hydrocarbon group or an aromatic hydrocarbon group, preferably 2 to 15 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 carbon atoms. An alkanediyl group (alkylene group) or an alkenylene group having 8 to 8 carbon atoms, an arylene group having 6 to 10 carbon atoms, more preferably a phenylene group, or a cyclic saturated or unsaturated hydrocarbon group having 3 to 8 carbon atoms. Specifically, ethylene group, trimethylene group, propane-1,2-diyl group, tetramethylene group, heptamethylene group, hexamethylene group, pentane-1,5-diyl group, octamethylene group, dodecamethylene group, phenylene Groups and the like. The same applies to the following equations.
m and n are each independently preferably 0 to 20, more preferably 0 to 15, still more preferably 1 to 15, particularly preferably 2 to 14, and most preferably 2 to 12.

AO is the number of carbon atoms such as ethyleneoxy group (EO), propyleneoxy group (trimethyleneoxy group or propane-1,2-diyloxy group) (PO), butyleneoxy group (tetramethyleneoxy group etc.) (BO), etc. 2 to 4 alkanediyloxy groups (alkyleneoxy groups), and when m and n are 2 or more, AO may be the same or different, and when they are different, AO may be added in blocks or randomly. It may be.
Examples of the substituent that R ^{1 to} R ³ may have include halogen atoms such as fluorine, chlorine and bromine atoms, alkoxy groups having 1 to 12 carbon atoms such as methoxy, ethoxy and isopropoxy groups, phenyloxy Aryloxy groups such as oxycarbonyl groups such as methoxycarbonyl groups, acyl groups such as acetyl and benzoyl groups, acyloxy groups such as acetyloxy groups, cyano groups, nitro groups, hydroxyl groups, carboxy groups, oxo groups, epoxy groups , Ether groups, ester groups and the like (these are collectively referred to as “substituents”). These substituents may be one or a combination of two or more.
The substituent that R ³ may have is preferably —CO (O) — (AO) _L —R ⁴ . In the formula, AO is the same as described above. L has the same meaning as m described above, and the preferred range is also the same. R ⁴ has the same meaning as R ¹ described above, and the preferred range is also the same. In this case, R ³ is preferably an aromatic hydrocarbon group.

(1) The aliphatic carboxylic acid ester is more specifically a compound in which, in the formula (1), R ³ is a divalent aliphatic hydrocarbon group which may have a substituent. preferable. Examples of this substituent include the above-described substituents.
Specific examples of the aliphatic carboxylic acid ester include dimethyl adipate, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis (butyldiethylene glycol) adipate, dimethyl sebacate, diethyl sebacate Examples thereof include aliphatic dibasic acid esters such as keto, dibutyl sebacate, bis (2-ethylhexyl) sebacate, diethyl succinate and bis (2-ethylhexyl) azelate. Among these, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (butyldiethylene glycol) adipate, bis (octoxypolyethylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl and EO average added moles m and n, respectively) = 1 to 4), bis (octoxypolypropylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, average added moles of PO and n = 1 to 6), bis (octoxypolyethyleneglycol / polypropylene) Propylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, EO and PO total average addition moles m and n = 4-12, block addition), bis [octoxypoly (ethylene glycol propylene glycol)] adipate (R ¹ and R ² are both 2 -Ethylhexyl, EO and PO total average addition moles m and n = 4-12, random addition), diethyl sebacate, dibutyl sebacate, diisobutyl sebacate, etc. Diesters are particularly preferred.

  (2) More specifically, the aromatic carboxylic acid ester is more preferably a compound represented by the following formula (2).

(In the formula, R ¹ and R ² have the same meaning as described above and may be the same or different. AO, m and n have the same meaning as described above, and m and n are 2 or more. AO may be the same or different.)
Specific examples of aromatic carboxylic acid esters include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, bis (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, octyl benzyl phthalate, nonyl Phthalic acid esters such as benzyl phthalate, stearyl benzyl phthalate, octyl decyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, bis (dimethylcyclohexyl) phthalate, bis (t-butylcyclohexyl) phthalate, ethyl phthalyl ethyl glycolate, tributyl trimellitate, Trimellitic acid esters such as triisobutyl trimellitate and tri (2-ethylhexyl) trimellitate It is below. Among these, 3 carbon atoms such as phthalic acid diester having an aliphatic alcohol residue having 1 to 5 carbon atoms such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, octyl benzyl phthalate, nonyl benzyl phthalate, stearyl benzyl phthalate Benzyl phthalate having -18 alkyl groups, bis (octoxypolyethylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, average addition number m of EO and n = 1-5), bis (octoxy Polypropylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, average added moles m and n of PO = 1 to 4), bis (octoxypolyethylene glycol / polypropylene glycol) phthalate (R ¹ and R ² Are both 2-Echi Hexyl, each total average addition mole number m and n = 4 to 12 of EO and PO, block addition), bis [Okutokishipori (ethylene glycol-propylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, EO and The total average number of moles of PO added m and n = 4 to 12, random addition) and the like, and phthalic acid esters such as tributyl trimellitate and triisobutyl trimellitate, The trimellitic acid diester is particularly preferred.

  (3) The cycloalkane (ken) carboxylic acid ester is more preferably a cyclohexane (cene) carboxylic acid ester represented by the following formula (3). (3) The cycloalkane (ken) carboxylic acid ester includes, as the cycloalkane (ken) group, a cyclic hydrocarbon group which may have one unsaturated group having 3 to 8 carbon atoms.

(In the formula, R ¹ and R ² have the same meaning as described above, and may be the same or different. AO, m and n have the same meaning as described above, and m and n are 2 or more. AO may be the same or different.)
Specific examples of the cycloalkane (ken) carboxylic acid ester include cyclohexane carboxylic acid esters such as 1,2-cyclohexanedicarboxylic acid dibutyl ester, 1,2-cyclohexanedicarboxylic acid diisononyl ester, and 3,4-cyclohexene dicarboxylic acid dibutyl ester. And cyclohexene carboxylic acid esters such as 3,4-cyclohexene carboxylic acid diisononyl ester.
(4) The phosphate ester is preferably a compound represented by the following formula (4).

(In the formula, R ¹ and R ² have the same meaning as described above and may be the same or different.)
(4) Specific examples of phosphate esters include tributyl phosphate, tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2 -Ethylhexyl diphenyl phosphate and the like. Among these, phosphate esters having a C5-C9 alkoxyalkyl group such as tris (butoxyethyl) phosphate, phosphate esters having a C4-12 aliphatic hydrocarbon group such as tributyl phosphate, tris ( Butoxyethyl) phosphates, tricresyl phosphates, trixylenyl phosphates, cresyl diphenyl phosphates, and other phosphate esters having an aromatic hydrocarbon group of 7 to 12 carbon atoms are particularly preferred. The phosphoric acid ester is preferably a phosphoric acid di- or triester.

  (5) Specific examples of oxyacid esters include triethyl acetylcitrate, tributyl acetylcitrate, and methyl acetylricinoleate.

  (6) Specific examples of glycol esters include diethylene glycol dibenzoate, triethylene glycol di (2-ethylhexoate), and the like.

  (7) Specific examples of the epoxy ester include butyl epoxy stearate and octyl epoxy stearate.

  (8) Specific examples of the sulfonamide include o- and p-toluenesulfonamide, N-butylbenzenesulfonamide and the like.

  (9) Specific examples of polyester include poly (1,2-butanediol adipate), poly (1,3-butanediol adipate) and the like.

  (10) Specific examples of the glyceryl alkyl ether include glyceryl monoether, glyceryl diether, and glyceryl triether. In these, the glyceryl monoether which has a C8-C30 linear or branched alkyl group is preferable. As carbon number of an alkyl group, More preferably, it is 8-22, More preferably, it is 8-14. There is no restriction | limiting in particular in the position of an alkyl group.

(11) Specific examples of the glyceryl alkyl ester include glyceryl monoalkyl ester, glyceryl dialkyl ester, and glyceryl trialkyl ester.
Among these, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, palmitic acid) Linear aliphatic carboxylic acids such as branched aliphatic carboxylic acids such as pivalic acid) esters are preferred. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
More specifically, glyceryl triacetate, glyceryl diacetate, glyceryl monoacetate and the like can be mentioned.

(12) Specific examples of glycol alkyl ether include glycol monoalkyl ether and glycol dialkyl ether.
Examples of the glycol include ethylene glycol and neopentyl glycol. Examples of the alkyl group include linear or branched alkyl groups having 1 to 22 carbon atoms. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
Said water-insoluble organic compound can be used individually or in mixture of 2 or more types. Among these, the compound represented by the formula (1) is preferable from the viewpoint of image clarity.

(Coloring agent)
The colorant used in the colored ink is not particularly limited, and pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.) can be used, but water resistance, storage stability and From the viewpoint of scratch resistance, pigments and hydrophobic dyes are preferred. Among them, it is preferable to use a pigment in order to express the high weather resistance which has been recently demanded. That is, the present invention is suitable for enhancing the image clarity and storage stability of water-based inks using pigments.
When the pigment and the hydrophobic dye are used in an aqueous ink, it is preferable to use a surfactant and a polymer to form fine particles that are stable in the ink. Furthermore, it is preferable to contain a pigment and / or a hydrophobic dye in the polymer particles from the viewpoint of bleeding resistance and water resistance.
The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments.
Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Of these, carbon black is preferred particularly for black aqueous inks. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.
Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments.
Specific examples of preferred organic pigments include C.I. I. Pigment yellow, C.I. I. Pigment Red, C.I. I. Pigment violet, C.I. I. Pigment blue, and C.I. I. One or more types of products selected from the group consisting of pigment green are listed.
Examples of extender pigments include silica, calcium carbonate, and talc.

The type of the hydrophobic dye is not particularly limited, but those that can be contained in the polymer particles are preferable. The hydrophobic dye is dissolved in an amount of 2 g / L or more, preferably 20 to 500 g / L (25 ° C.) with respect to the organic solvent (preferably methyl ethyl ketone) used in the production of the polymer from the viewpoint of efficiently containing the dye in the polymer. What to do is desirable.
Examples of the hydrophobic dye include oil-soluble dyes and disperse dyes. Among these, oil-soluble dyes are preferable.
Examples of the oil-soluble dye include C.I. I. Solvent Black, C.I. I. Solvent Yellow, C.I. I. Solvent Red, C.I. I. Solvent Violet, C.I. I. Solvent Blue, C.I. I. Solvent Green, and C.I. I. One or more types of products selected from the group consisting of Solvent Orange are listed, which are commercially available from Orient Chemical Co., Ltd., BASF Corp. and others.
The above colorants can be used alone or in admixture of two or more at any ratio.

(Polymer particles)
Among the water-based inks used in the present invention, the water-based ink hit first may contain polymer particles from the viewpoint of containing a water-insoluble organic compound in the polymer particles and stabilizing in the water-based ink. preferable.
Furthermore, the water-insoluble organic compound in the water-based ink dots that have been struck first effectively spreads the dots of the ink that will be struck over again, from the viewpoint of improving image clarity. It is preferable that the water-based ink to be hit also contains polymer particles.
Therefore, the water-based ink constituting the ink set used in the present invention preferably contains polymer particles. In the case of a colored ink, a colorant can be contained in the polymer particles in the water-based ink, and the colorant can be stably dispersed.

  The polymer used for the polymer particles is preferably a water-insoluble polymer from the viewpoint of improving image clarity and stabilizing a water-insoluble organic compound or a colorant. Here, the water-insoluble polymer means that when the polymer is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolution amount is 10 g or less, preferably 5 g or less, more preferably 1 g or less. Is a polymer. When the polymer has a salt-forming group, the dissolution amount is a dissolution amount when the salt-forming group of the polymer is neutralized 100% with acetic acid or sodium hydroxide depending on the type.

Examples of the polymer to be used include vinyl polymers, polyesters, polyurethanes and the like. From the viewpoint of storage stability, vinyl polymers obtained by addition polymerization of vinyl monomers (vinyl compounds, vinylidene compounds, vinylene compounds) are preferable.
Examples of the polymer particles include vinyl polymer particles, ester polymer particles, and urethane polymer particles. These particles are preferably polymer particles that can be dispersed as a polymer emulsion in a medium containing a continuous phase in an aqueous system in the presence or absence of a surfactant. In particular, (i) emulsion polymer particles obtained by emulsion polymerization of an ethylenically unsaturated monomer using a surfactant and / or reactive surfactant, and (ii) a structural unit derived from a salt-forming group-containing monomer. Self-emulsifying polymer particles are preferred.
The (ii) self-emulsifying polymer particles refer to polymer particles that are emulsified in water by a functional group (particularly a basic group or a salt thereof) of the polymer itself in the absence of a surfactant.
Here, the emulsified state means a solution in which 30 g of polymer is dissolved in 70 g of an organic solvent (for example, methyl ethyl ketone), a neutralizing agent capable of neutralizing 100% of the salt-forming group of the water-insoluble polymer (if the salt-forming group is anionic). Sodium hydroxide, acetic acid if cationic) and 200 g of water are mixed and stirred (30 minutes, 25 ° C.), and then the organic solvent is removed from the mixed solution. It means a state in which it can be visually confirmed that it exists stably for at least one week at ° C.

(Vinyl polymer)
As the vinyl polymer, (a) a salt-forming group-containing monomer (hereinafter sometimes referred to as “(a) component”), (b) a macromer (hereinafter sometimes referred to as “(b) component”) and / or (c ) A vinyl polymer obtained by copolymerizing a monomer mixture (hereinafter also referred to as “monomer mixture”) containing a hydrophobic monomer (hereinafter also referred to as “component (c)”) is preferable. This vinyl polymer has a structural unit derived from the component (a), a structural unit derived from the component (b) and / or a structural unit derived from the component (c). A more preferable vinyl polymer has a structural unit derived from the component (a) or a structural unit derived from the components (a) and (c) as a main chain, and a graft having a structural unit derived from the component (b) as a side chain. It is a polymer.

(A) The salt-forming group-containing monomer is used from the viewpoint of enhancing the storage stability of the resulting dispersion. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group, and a carboxy group is particularly preferable.
Examples of the salt-forming group-containing monomer include cationic monomers and anionic monomers described in JP-A-9-286939, paragraph [0022].
Representative examples of the cationic monomer include unsaturated amine-containing monomers and unsaturated ammonium salt-containing monomers. Among these, N, N-dimethylaminoethyl (meth) acrylate, N- (N ′, N′-dimethylaminopropyl) (meth) acrylamide and vinylpyrrolidone are preferable.
Representative examples of anionic monomers include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and the like.
Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid. Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconic acid ester, and the like. Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, etc. Is mentioned.
Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of storage stability and ejection stability.

(B) The macromer is used from the viewpoint of enhancing the storage stability of the polymer particles. The macromer includes a macromer which is a monomer having a polymerizable unsaturated group having a number average molecular weight of 500 to 100,000, preferably 1,000 to 10,000. In addition, the number average molecular weight of (b) macromer is measured using polystyrene as a standard substance by gel chromatography using chloroform containing 1 mmol / L of dodecyldimethylamine as a solvent.
Among (b) macromers, from the viewpoint of storage stability of polymer particles, styrene macromers and aromatic group-containing (meth) acrylate macromers having a polymerizable functional group at one end are preferable.
Examples of the styrenic macromer include a styrene monomer homopolymer or a copolymer of a styrene monomer and another monomer. Examples of the styrene monomer include styrene, 2-methylstyrene, vinyl toluene, ethyl vinyl benzene, vinyl naphthalene, chlorostyrene, and the like.

Examples of the aromatic group-containing (meth) acrylate-based macromer include a homopolymer of an aromatic group-containing (meth) acrylate or a copolymer thereof with another monomer. As an aromatic group-containing (meth) acrylate, an arylalkyl having 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably 7 to 12 carbon atoms, which may have a substituent containing a hetero atom. (Meth) acrylate having an aryl group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a group or a substituent containing a hetero atom In addition, examples of the substituent containing a hetero atom include a halogen atom, an ester group, an ether group, and a hydroxy group. Examples include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, and benzyl (meth) acrylate is particularly preferable.
The polymerizable functional group present at one end of the macromer is preferably an acryloyloxy group or a methacryloyloxy group, and the other monomer to be copolymerized is preferably acrylonitrile.
The content of the styrene monomer in the styrene macromer or the aromatic group-containing (meth) acrylate in the aromatic group-containing (meth) acrylate macromer is preferably 50% by weight from the viewpoint of increasing the affinity with the pigment. Above, more preferably 70% by weight or more.

(B) The macromer may have a side chain composed of another structural unit such as an organopolysiloxane. This side chain can be obtained, for example, by copolymerizing a silicone macromer having a polymerizable functional group at one end represented by the following formula (5).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _{t -Si (CH 3) 3 (} 5)
(In the formula, t represents a number of 8 to 40).
Examples of commercially available styrenic macromers as component (b) include Toa Gosei Co., Ltd. trade names, AS-6 (S), AN-6 (S), HS-6 (S), and the like. It is done.

(C) The hydrophobic monomer is used from the viewpoint of improving the printing density. Examples of the hydrophobic monomer include alkyl (meth) acrylates and aromatic group-containing monomers.
As the alkyl (meth) acrylate, those having an alkyl group having 1 to 22 carbon atoms, preferably 6 to 18 carbon atoms are preferable. For example, methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meta) ) Acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) Examples include decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, and (iso) stearyl (meth) acrylate.
In the present specification, “(iso or tertiary)” and “(iso)” mean both the case where these groups are present and the case where these groups are not present. Indicates. “(Meth) acrylate” indicates acrylate, methacrylate, or both.

The aromatic group-containing monomer has an aromatic group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a substituent containing a hetero atom. Vinyl monomers are preferable, and examples thereof include the styrene monomer (c-1 component) and the aromatic group-containing (meth) acrylate (c-2 component). The above-mentioned thing is mentioned as a substituent containing a hetero atom.
Among the components (c), a styrene monomer (c-1 component) is preferable from the viewpoint of improving printing density, and styrene and 2-methylstyrene are particularly preferable as the styrene monomer. The content of the component (c-1) in the component (c) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving printing density.
Moreover, as an aromatic group containing (meth) acrylate (c-2) component, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, etc. are preferable. The content of the component (c-2) in the component (c) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving printing density and gloss. Moreover, it is also preferable to use (c-1) component and (c-2) component together.

The monomer mixture may further contain (d) a hydroxyl group-containing monomer (hereinafter sometimes referred to as “component (d)”). (D) A hydroxyl group-containing monomer is used to further improve storage stability.
As the component (d), for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, polyethylene glycol (n = 2 to 30, n represents the average number of added moles of oxyalkylene group. The same)) (meth) acrylate, polypropylene glycol (n = 2-30) (meth) acrylate, poly (ethylene glycol (n = 1-15) / propylene glycol (n = 1-15)) (meth) acrylate, etc. Can be mentioned. Among these, 2-hydroxyethyl (meth) acrylate, polyethylene glycol monomethacrylate, and polypropylene glycol methacrylate are preferable.

The monomer mixture may further contain (e) a monomer represented by the following formula (6) (hereinafter sometimes referred to as “(e) component”).
^{_{CH 2 = C (R 5)}} COO (R 6 O) q R 7 (6)
Wherein R ⁵ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ⁶ is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ⁷ is A monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom or a phenyl group optionally having an alkyl group having 1 to 9 carbon atoms, q means the average number of moles added. , 1 to 60, preferably 1 to 30.)
The component (e) is used for further improving the dischargeability.
As a hetero atom contained in the monomer of Formula (12), a nitrogen atom, an oxygen atom, a halogen atom, and a sulfur atom are mentioned, for example.
Preferable examples of R ⁵ include a methyl group, an ethyl group, and an (iso) propyl group.
Preferred examples of the R ⁶ O group include an oxyethylene group, an oxytrimethylene grave, an oxypropane-1,2-diyl group, an oxytetramethylene group, an oxyheptamethylene group, an oxyhexamethylene group, and two or more kinds thereof. Examples thereof include oxyalkanediyl groups having 2 to 7 carbon atoms (oxyalkylene groups).
Preferable examples of R ⁷ include an aliphatic alkyl group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, an alkyl group having 7 to 30 carbon atoms having an aromatic ring, and Examples thereof include an alkyl group having 4 to 30 carbon atoms having a hetero ring and an optionally substituted phenyl group having 1 to 8 carbon atoms.

  Specific examples of the component (e) include methoxypolyethylene glycol (1 to 30: the value of q in the formula (6); hereinafter the same) (meth) acrylate, methoxypolytetramethylene glycol (1 to 30) ( (Meth) acrylate, ethoxy polyethylene glycol (1-30) (meth) acrylate, octoxy polyethylene glycol (1-30) (meth) acrylate, polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether, (iso) Propoxy polyethylene glycol (1-30) (meth) acrylate, butoxypolyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Polymerization) (1-30, ethylene glycol therein: 1-29) (meth) acrylate, phenoxy (ethylene glycol / propylene glycol copolymer) (1-30, ethylene glycol therein: 1-29) (meth) An acrylate etc. are mentioned. Among these, octoxypolyethylene glycol (1-30) (meth) acrylate and polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether are preferable.

Specific examples of commercially available (d) and (e) components include Shin-Nakamura Chemical Co., Ltd. polyfunctional acrylate monomer (NK ester) M-40G, 90G, 230G, and Nippon Oil & Fats Co., Ltd. BLEMMER series, PE-90, 200, 350, PME-100, 200, 400, 1000, PP-500, 800, 1000, AP-150, 400, 550, 800 , 50PEP-300, 50POEP-800B, 43PAPE600B, and the like.
The components (a) to (e) can be used alone or in admixture of two or more.

Content derived from the components (a) to (e) in the monomer mixture at the time of polymer production (content as an unneutralized amount; the same applies hereinafter) or the components (a) to (e) in the polymer The content of the unit is as follows.
The content of the component (a) is preferably 2 to 40% by weight, more preferably 2 to 30% by weight, and particularly preferably 3 to 20% by weight from the viewpoint of storage stability of the resulting dispersion.
The content of the component (b) is preferably 1 to 25% by weight, more preferably 5 to 20% by weight, particularly from the viewpoint of enhancing the interaction with the colorant.
The content of the component (c) is preferably 5 to 98% by weight, more preferably 10 to 60% by weight, from the viewpoint of improving print density.
The content of component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight, from the viewpoint of storage stability of the resulting dispersion.
The content of the component (e) is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of improving dischargeability.
The total content of [component (a) + component (d)] in the monomer mixture is preferably 6 to 60% by weight, more preferably 10 to 50% by weight, from the viewpoint of storage stability of the resulting dispersion. is there. The total content of [component (a) + component (e)] is preferably 6 to 75% by weight, more preferably 13 to 50% by weight, from the viewpoint of storage stability and dischargeability of the resulting dispersion. . The total content of [(a) component + (d) component + (e) component] is preferably 6 to 60% by weight, more preferably from the viewpoint of storage stability and dischargeability of the resulting dispersion. 7 to 50% by weight.
The weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.01 to 1, more preferably from the viewpoint of storage stability and print density of the resulting dispersion. Is 0.02 to 0.67, more preferably 0.03 to 0.50.

(Manufacture of polymers)
The polymer used in the present invention is produced by copolymerizing a monomer mixture by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable.
The solvent used in the solution polymerization method is not particularly limited, but a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol, and propanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate. Among these, methanol, ethanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, or a mixed solvent of one or more of these and water are preferable.
In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), t-butyl peroxyoctate, dibenzoyl oxide, etc. Known radical polymerization initiators such as organic peroxides can be used.
The amount of the radical polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture.
In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol and thiuram disulfide may be further added.

Since the polymerization conditions of the monomer mixture vary depending on the type of radical polymerization initiator, monomer, and solvent used, it cannot be determined unconditionally. Usually, the polymerization temperature is preferably 30 to 100 ° C, more preferably 50 to 80 ° C, and the polymerization time is preferably 1 to 20 hours. The polymerization atmosphere is preferably a nitrogen gas atmosphere or an inert gas atmosphere such as argon.
After completion of the polymerization reaction, the produced polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained polymer can be purified by repeating reprecipitation or by removing unreacted monomers and the like by membrane separation, chromatographic method, extraction method and the like.

The weight average molecular weight of the polymer used in the present invention is preferably 5,000 to 500,000, more preferably 10,000 to 400,000, and more preferably 10,000 to 300,000, from the viewpoints of image clarity and storage stability of the colorant. Preferred is 20,000 to 300,000. In addition, the weight average molecular weight of the polymer was measured by the method shown in the Examples.
When the polymer used in the present invention has (a) a salt-forming group derived from a salt-forming group-containing monomer, it is neutralized with a neutralizing agent. As the neutralizing agent, an acid or a base can be used depending on the type of the salt-forming group in the polymer. For example, hydrochloric acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid, lactic acid, succinic acid, glycolic acid, gluconic acid, glyceric acid and other acids, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methylamine, dimethylamine , Bases such as trimethylamine, ethylamine, diethylamine, triethylamine, triethanolamine, and tributylamine.

The degree of neutralization of the salt-forming group is preferably 10 to 200%, more preferably 20 to 150%, and particularly preferably 50 to 150%.
Here, the degree of neutralization can be determined by the following formula when the salt-forming group is an anionic group.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [acid value of polymer (KOH mg / g) × polymer weight (g) / (56 × 1000)]} × 100
When the salt-forming group is a cationic group, it can be determined by the following formula.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine value of polymer (HCL mg / g) × polymer weight (g) / (36.5 × 1000)]} × 100
The acid value and amine value can be calculated from the structural unit of the polymer. Alternatively, it can also be determined by a method in which a polymer is dissolved in an appropriate solvent (for example, methyl ethyl ketone) and titrated. The acid value or amine value of the polymer is preferably 50 to 200, more preferably 50 to 150.

(Crosslinked polymer particles)
The water-based ink used in the present invention may preferably contain crosslinked polymer particles as polymer particles. When the polymer particles used in the clear ink are cross-linked polymer particles, image clarity and storage stability can be improved, which is preferable. When the polymer particles used in the colored ink are cross-linked polymer particles, storage stability can be improved, which is preferable.

(Crosslinking agent)
In the production of the crosslinked polymer particles, it is preferable to use a crosslinking agent having at least two reactive functional groups (hereinafter also simply referred to as “crosslinking agent”) from the viewpoint of appropriately crosslinking the polymer. The molecular weight of the cross-linking agent is preferably 120 to 2000, more preferably 150 to 1500, and particularly preferably 150 to 1000, from the viewpoint of easy reaction and storage stability of the resulting cross-linked polymer particles.
The number of reactive functional groups contained in the crosslinking agent is preferably 2 to 6 from the viewpoint of controlling the molecular weight and improving storage stability. Preferred examples of the reactive functional group include one or more selected from the group consisting of a hydroxyl group, an epoxy group, an aldehyde group, an amino group, a carboxy group, an oxazoline group, and an isocyanate group.
The number of reactive functional groups is preferably 2 to 4 from the viewpoint of improving the image clarity by controlling the molecular weight. The reactive functional group is preferably at least one selected from the group consisting of a hydroxyl group, an epoxy group, an aldehyde group, an amino group, and a carboxy group.
Specific examples of the crosslinking agent include the following (a) to (g).
(A) Compounds having two or more hydroxyl groups in the molecule: for example, polyhydric alcohols such as ethylene glycol, diethylene glycol, and triethylene glycol.
(B) Compound having two or more epoxy groups in the molecule: for example, polyglycol such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether Glycidyl ether.
(C) Compounds having two or more aldehyde groups in the molecule: for example, polyaldehydes such as glutaraldehyde and glyoxal.
(D) Compounds having two or more amino groups in the molecule: for example, polyamines such as ethylenediamine and polyethyleneimine.
(E) Compounds having two or more carboxy groups in the molecule: for example, polyvalent carboxylic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid and adipic acid.
(F) Compound having two or more oxazoline groups in the molecule: for example, a compound in which 2 or more, preferably 2 to 3 oxazoline groups are bonded to an aliphatic group or an aromatic group, more specifically 2 , 2′-bis (2-oxazoline), 1,3-phenylenebisoxazoline, bisoxazoline compounds such as 1,3-benzobisoxazoline, and terminal oxazoline groups obtained by reacting the compound with a polybasic carboxylic acid (G) Compound having two or more isocyanate groups in the molecule: for example, organic polyisocyanate or isocyanate group-terminated prepolymer.

The polymer has a reactive group (crosslinkable functional group) capable of reacting with a crosslinking agent, and a suitable combination example of both is as follows.
When the reactive group of the polymer is an anionic group such as a carboxy group, a sulfonic acid group, a sulfuric acid group, a phosphonic acid group, or a phosphoric acid group, the cross-linking agents are the above (a), (b), (d) and (f ) Compounds are preferred. When the reactive group of the polymer is an amino group, the crosslinking agent is preferably the compounds (b), (c) and (e). When the reactive group of the polymer is a hydroxyl group, the crosslinking agent is preferably the compounds (c) and (e). When the reactive group of the polymer is an isocyanate group or an epoxy group, the crosslinking agent is preferably the compounds (a), (d) and (e).
Among the above combinations, the crosslinking agent preferably has a functional group that reacts with the anionic group of the polymer from the viewpoint of controlling the polymer so as to impart an appropriate crosslinking structure. (B) 2 in the molecule A combination with a compound having one or more epoxy groups is particularly preferred.

(Colorant-containing polymer particles / colorant-containing crosslinked polymer particles)
In the present invention, it is preferable to use colorant-containing polymer particles from the viewpoint of incorporating a colorant into the polymer particles, and from the viewpoint of excellent storage stability even when a water-insoluble organic compound is contained, a crosslinked polymer containing the colorant. It is more preferable to use particles (hereinafter sometimes referred to as “colorant-containing crosslinked polymer particles”).

The colorant-containing polymer particles can be produced, for example, by the following steps (1) and (2). The colorant-containing crosslinked polymer particles can be produced, for example, by the following steps (1) to (3).
Step (1): A step of dispersing a mixture containing a polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent to obtain a dispersion of colorant-containing polymer particles. Step (2): Step (1) Step of removing the organic solvent from the dispersion obtained in step 1) to obtain an aqueous dispersion of the colorant-containing polymer particles Step (3): cross-linking the polymer of the colorant-containing polymer particles obtained in step (2) Cross-linking with a colorant to obtain an aqueous dispersion of colorant-containing cross-linked polymer particles

In step (1), the polymer is first dissolved in an organic solvent, and then a colorant, water, and, if necessary, a neutralizing agent and a surfactant are added to and mixed with the obtained organic solvent solution. A method for obtaining an oil-in-water type dispersion is preferred. In the mixture, the colorant is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, the organic solvent is preferably 10 to 70% by weight, more preferably 10 to 50% by weight, and the polymer is 2 to 2% by weight. It is preferably 40% by weight, more preferably 3 to 20% by weight, and water is preferably 10 to 70% by weight, more preferably 20 to 70% by weight.
When the polymer has a salt-forming group, it is preferable to use a neutralizing agent. There is no particular limitation on the degree of neutralization when neutralizing with a neutralizer. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5 to 10. The pH can also be determined by the desired degree of neutralization of the polymer. Examples of the neutralizing agent include those described above. Further, the polymer may be neutralized in advance.
Examples of the organic solvent include alcohol solvents such as ethanol, isopropanol and isobutanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone, and ether solvents such as dibutyl ether, tetrahydrofuran and dioxane. Preferably, the amount dissolved in 100 g of water is preferably 5 g or more at 20 ° C., more preferably 10 g or more, more specifically preferably 5 to 80 g, more preferably 10 to 50 g, particularly methyl ethyl ketone. And methyl isobutyl ketone are preferred.

There is no restriction | limiting in particular in the dispersion method of the mixture in process (1). Although the average particle size of the polymer particles can be atomized only by this dispersion until the desired particle size is reached, preferably after pre-dispersion using a commonly used mixing and stirring device such as an anchor blade, further shearing is performed. It is preferable to control the average particle size of the polymer particles so as to obtain a desired particle size by applying stress and applying this dispersion. 5-50 degreeC is preferable and dispersion | distribution of a process (1) has more preferable 10-35 degreeC.
As means for giving the shear stress of this dispersion, for example, a kneader such as a roll mill, a bead mill, a kneader, an extruder, a high-pressure homogenizer (Izumi Food Machinery Co., Ltd., trade name), a minilab 8.3H type (Rannie Co., trade name) Examples thereof include a chamber type high-pressure homogenizer such as a homo-valve type high-pressure homogenizer, a microfluidizer [Microfluidics, trade name], and a nanomizer [Nanomizer Co., trade name]. A plurality of these devices can be combined. Among these, when a pigment is used, a high-pressure homogenizer is preferable from the viewpoint of reducing the particle size of the pigment.

In step (2), an aqueous dispersion of colorant-containing polymer particles can be obtained by distilling off the organic solvent from the obtained dispersion by a known method. The organic solvent in the aqueous dispersion containing the obtained polymer particles is preferably substantially removed, but may remain as long as the object of the present invention is not impaired. It may be removed again later. The amount of the residual organic solvent is preferably 0.1% by weight or less, and more preferably 0.01% by weight or less.
The obtained aqueous dispersion of polymer particles containing the colorant is one in which the solid content of the polymer containing the colorant is dispersed in water as a main medium. Here, the form of the polymer particles is not particularly limited as long as the composite particles are formed of at least a colorant and a polymer. For example, a particle form in which a colorant is included in a polymer, a particle form in which a colorant is uniformly dispersed in a polymer, a particle form in which a colorant is exposed on the surface of a polymer particle, and the like are included.

In the step (3), the obtained colorant-containing polymer particles can be crosslinked with a crosslinking agent to obtain colorant-containing crosslinked polymer particles. In the step (3), from the viewpoint of storage stability, a method of cross-linking the polymer by mixing an aqueous dispersion of colorant-containing polymer particles and a cross-linking agent is preferable. Further, the catalyst, solvent, reaction temperature, and reaction time can be appropriately selected and determined depending on the crosslinking agent used. The reaction time is preferably 0.5 to 10 hours, more preferably 1 to 5 hours, and the reaction temperature is preferably 40 to 95 ° C.
Further, as the polymer crosslinking step, the polymer can be crosslinked by mixing the dispersion of polymer particles containing the colorant obtained in the step (1) and the crosslinking agent. In this case, an aqueous dispersion of crosslinked polymer particles containing a colorant is obtained by performing the step of removing the organic solvent from the dispersion of crosslinked polymer particles obtained in the crosslinking step in the same manner as in the step (2). Can be obtained.
The degree of crosslinking of the colorant-containing crosslinked polymer particles is preferably 0.5 to 20% by weight, more preferably 0.6 to 15% by weight, still more preferably 0.7 to 10% by weight, from the viewpoint of storage stability. Most preferably, it is 0.8 to 8 weight%.
The degree of crosslinking of the colorant-containing crosslinked polymer particles by the crosslinking agent can be determined by the method described later.

(Polymer particles for clear ink / crosslinked polymer particles for clear ink)
The clear ink used in the present invention preferably contains polymer particles from the viewpoint of improving image clarity, but contains crosslinked polymer particles from the viewpoint of excellent storage stability even if a water-insoluble organic compound is contained. More preferably.

The polymer particles used in the clear ink can be obtained by the same production method as the colorant-containing polymer particles in the steps (1) and (2) except that the polymer particles do not contain a colorant. The crosslinked polymer particles used in the clear ink can be obtained by the same production method as the colorant-containing crosslinked polymer particles in the steps (1) to (3) except that the polymer does not contain a colorant.
The crosslinking degree of the crosslinked polymer particles is preferably 0.5 to 20% by weight, more preferably 0.6 to 15% by weight, still more preferably 0.7 to 10% by weight, particularly preferably from the viewpoint of storage stability. 0.8 to 8% by weight.
The degree of cross-linking with the cross-linking agent of the cross-linked polymer particles for clear ink can be determined by the method described below.

Crosslinked polymer particles can also be produced by the following steps 1 and 2.
Step 1: Obtain an emulsion composition containing a polymer, a crosslinkable monomer having at least two reactive unsaturated groups in the molecule, an organic solvent, a hydrophobic monomer if necessary, and water Step 2: Obtained in Step 1 A step of obtaining a dispersion of crosslinked polymer particles by polymerizing the hydrophobic monomer and the crosslinking monomer in the obtained emulsion composition

In step 1, the polymer is first dissolved in an organic solvent, and then a crosslinkable monomer having at least two reactive unsaturated groups in the molecule, a hydrophobic monomer if necessary, water, and neutralization as necessary. A method of adding an agent, a surfactant and the like and mixing them to obtain an emulsified composition is preferred. In the emulsion composition, the organic solvent is preferably 5 to 60% by weight, more preferably 5 to 40% by weight, the polymer is preferably 1 to 30% by weight, more preferably 3 to 20% by weight, and the hydrophobic monomer is 1 to 30 wt% is preferable, 2 to 20 wt% is more preferable, the crosslinkable monomer is preferably 10 to 70 wt%, more preferably 20 to 70 wt%, and water is preferably 30 to 90 wt%, More preferably, it is 40 to 85% by weight. Preferred examples of the polymer and the organic solvent include those described above.
There is no particular limitation on the degree of neutralization when the polymer has a salt-forming group. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5-10. Further, a water-insoluble polymer having a salt-forming group may be neutralized in advance. Examples of the neutralizing agent include those described above.

Although there is no restriction | limiting in particular in the emulsification method in the process 1, It is preferable to fully emulsify a monomer mixture by the ultrasonic dispersion method etc. As an ultrasonic disperser, what has a frequency of 20 to 2000 kHz and a wattage per liter of the total reaction volume is preferably 20 to 1000 W, more preferably 50 to 800 W. Such an ultrasonic disperser is commercially available from Nippon Seiki Seisakusho, Alex Co., Ltd. The emulsification conditions in step 1 are preferably 5 to 50 ° C., and preferably about 0.5 to 3 hours.
The amount of the crosslinkable monomer having at least two reactive unsaturated groups in the molecule is 0 with respect to 100 parts by weight of the total of the hydrophobic monomer and the crosslinkable monomer from the viewpoint of image clarity and storage stability. 5 to 20 parts by weight is preferable, and 1 to 10 parts by weight is more preferable.

  Here, examples of the hydrophobic monomer include alkyl (meth) acrylates and aromatic group-containing monomers. Specific examples thereof include the hydrophobic monomers described in the polymer column. Among these, styrene monomers such as styrene and 2-methylstyrene, and aromatic group-containing (meth) acrylates such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are particularly preferable.

  Crosslinkable monomers having at least two reactive unsaturated groups in the molecule (also simply referred to as “crosslinkable monomers”) include: (1) ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol (Meth) acrylic acid ester compounds of polyhydric alcohols such as di (meth) acrylate and propylene glycol di (meth) acrylate; (2) acrylamide compounds such as N-methylallylacrylamide and bisacrylamide acetic acid; (3) divinylbenzene and the like (4) polyallyl compounds such as allyl etherified pentaerythritol, and the like.

In step 2, the hydrophobic monomer and the crosslinkable monomer in the obtained emulsion composition can be polymerized to obtain a dispersion of crosslinked polymer particles.
The catalyst, solvent, temperature, and time in the above reaction can be appropriately determined in consideration of the monomer to be used. The reaction time is preferably 0.5 to 10 hours, more preferably 1 to 5 hours, and the reaction temperature is preferably 40 to 95 ° C.
From the viewpoint of storage stability, the degree of crosslinking of the crosslinked polymer particles by the crosslinking monomer is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, still more preferably 1 to 10% by weight, particularly preferably. 2 to 8% by weight.
The degree of crosslinking of the colorant-containing crosslinked polymer particles and the crosslinked polymer particles for clear ink can be determined by the following formula.
Crosslinking degree of crosslinked polymer particles (% by weight) = [(crosslinkable monomer amount + crosslinker amount) / crosslinked polymer amount] × 100 (7)
The total amount of crosslinked polymer is the amount of polymer after crosslinking.
In the case of crosslinking with a crosslinking agent: The total amount of the crosslinked polymer is a total amount calculated by adding the amount of the crosslinking agent and the amount of the polymer, and the amount of the crosslinking monomer of the molecule is zero.
In the case of cross-linking with a cross-linkable monomer: The total amount of the cross-linked polymer is the total calculated amount of the cross-linkable monomer amount, the hydrophobic monomer amount and the polymer amount, and the cross-linking agent amount of the molecule is zero.
Both a crosslinking monomer and a crosslinking agent can be used.

(Clear ink)
The clear ink used in the present invention is preferably an ink containing a water-insoluble organic compound and polymer particles or crosslinked polymer particles. For the clear ink, the aqueous dispersion of polymer particles or the aqueous dispersion of crosslinked polymer particles obtained above can be preferably used.
The clear ink may contain a wetting agent, a penetrating agent, a dispersing agent, a viscosity modifier, an antifoaming agent, an antifungal agent, an anticorrosive agent, and the like that are usually used for water-based inks for inkjet recording.
The content (solid content) of the polymer particles and / or crosslinked polymer particles in the clear ink is preferably 0.3 to 15% by weight, more preferably 0.5 to 12% by weight, from the viewpoint of image clarity. 7-10% by weight is particularly preferred. The water content is preferably 60 to 95% by weight, more preferably 60 to 90% by weight.
When the clear ink contains a water-insoluble organic compound, the water dispersion containing the polymer particles and / or cross-linked polymer particles and the water-insoluble organic compound are mixed and dispersed as appropriate so that at least the water-insoluble organic compound is mixed. Some are contained in the polymer particles and stabilized.
The content when the water-insoluble organic compound is contained in the clear ink is preferably 0.05 to 3% by weight, more preferably 0.05 to 2% by weight, and particularly preferably 0.1 to 1.5% by weight. It is.
The weight ratio of the polymer particles and / or crosslinked polymer particles to the water-insoluble organic compound [water-insoluble organic compound / (polymer particle or crosslinked polymer particle)] is preferably 1/100 to 1/1, and 1/20 to 1 / 5 is more preferable.
The average particle size of the polymer particles and the crosslinked polymer particles is preferably 10 to 500 nm, more preferably 30 to 300 nm, and particularly preferably 50 to 200 nm, from the viewpoint of preventing clogging of the printer nozzle and dispersion stability. In addition, an average particle diameter can be measured on condition of the following using laser particle analysis system ELS-8000 (cumulant analysis) of Otsuka Electronics Co., Ltd., for example.
Measurement conditions: temperature of 25 ° C., angle 90 °, integrated 100 times, the input refractive index of water (1.333) as a refractive index of the dispersing medium, measuring a concentration usually 5 × 10- ³ weight between incident light and detector %degree

(Colored ink)
The colored ink used in the present invention is preferably an ink containing a water-insoluble organic compound, a colorant, and polymer particles or crosslinked polymer particles. For the colored ink, the aqueous dispersion of the colorant-containing polymer particles obtained above or the aqueous dispersion of the colorant-containing crosslinked polymer particles can be preferably used.
The content of the colorant in the colored ink is preferably 1 to 15% by weight, more preferably 2 to 12% by weight, and still more preferably 3 to 10% by weight.
Commonly used wetting agents, penetrating agents, dispersants, viscosity modifiers, antifoaming agents, antifungal agents, rustproofing agents and the like may be added to the colored ink.
The content (solid content) of the polymer particles and / or crosslinked polymer particles in the colored ink is preferably 0.3 to 15% by weight, more preferably 0.5 to 12% by weight, from the viewpoint of image clarity. 7-10% by weight is particularly preferred.
From the viewpoint of storage stability, the colorant is preferably contained in the polymer particle to become a colorant-containing polymer particle or a colorant-containing crosslinked polymer particle.

The content of the colorant-containing polymer particles or the colorant-containing crosslinked polymer particles is preferably 1 to 20% by weight, more preferably 1.5 to 15% by weight, and preferably 1.5 to 12% by weight. The content of water is preferably 50 to 80% by weight, more preferably 60 to 80% by weight.
When the colored ink contains a water-insoluble organic compound, the water-insoluble organic compound is mixed with the water dispersion containing the colorant-containing polymer particles or the colorant-containing cross-linked polymer particles and the water-insoluble organic compound, and appropriately dispersed, whereby the water-insoluble organic compound is mixed. At least a portion of the compound is contained in the polymer particles and stabilized.
The content when the water-insoluble organic compound is contained in the colored ink is preferably 0.05 to 3% by weight, more preferably 0.05 to 2% by weight, and particularly preferably 0.1 to 1.5% by weight. It is. The weight ratio of the polymer particles and / or crosslinked polymer particles to the water-insoluble organic compound [water-insoluble organic compound / (polymer particle or crosslinked polymer particle)] is preferably 1/100 to 1/1, and 1/20 to 1 / 5 is more preferable.

The average particle diameter of the colorant-containing polymer particles and the colorant-containing crosslinked polymer particles is preferably 10 to 500 nm, more preferably 30 to 300 nm, and particularly preferably 50 from the viewpoint of preventing clogging of the nozzle of the printer and dispersion stability. ~ 200 nm. The method for measuring the average particle size is the same as described above.
The surface tension (20 ° C.) in the clear ink and the colored ink is preferably 25 to 50 mN / m, more preferably 27 to 45 mN / m.
The viscosity (20 ° C.) of the clear ink and the colored ink is preferably 2 to 12 mPa · s, more preferably 2.5 to 10 mPa · s, from the viewpoint of maintaining good dischargeability.

In the following production examples, examples and comparative examples, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.
Production Example 1 (Production of polymer)
In a reaction vessel, 20 parts of methyl ethyl ketone, 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol), and 10% of 200 parts of the monomer mixture shown in Table 1 are mixed and mixed, and nitrogen gas replacement is sufficiently performed. And a mixed solution was obtained.
On the other hand, the remaining 90% of the monomer mixture shown in Table 1 was charged into the dropping funnel, and 0.27 part of the polymerization chain transfer agent, 60 parts of methyl ethyl ketone and a radical polymerization initiator (2,2′-azobis (2,4- Dimethylvaleronitrile)) 1.2 parts were added and mixed, and the gas was sufficiently replaced with nitrogen gas to obtain a mixed solution.
Under a nitrogen atmosphere, the mixed solution in the reaction vessel was heated to 65 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped over 3 hours. After 2 hours at 65 ° C. from the end of dropping, a solution obtained by dissolving 0.3 part of the radical polymerization initiator in 5 parts of methyl ethyl ketone was added, and further aged at 65 ° C. for 2 hours and 70 ° C. for 2 hours to obtain a polymer solution. It was.
The weight average molecular weight of the obtained polymer was measured by the method described below. The results are shown in Table 1.

(1) Weight average molecular weight of polymer Gel chromatography using N, N-dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent [GPC apparatus (HLC- 8120GPC), a column manufactured by Tosoh Corporation (TSK-GEL, α-M × 2), flow rate: 1 mL / min], using polystyrene as a standard substance.

The details of the compounds shown in Table 1 are as follows.
Styrene macromer: manufactured by Toa Gosei Co., Ltd., trade name: AS-6 (S) (50% toluene solution, solid content 15 parts), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group, polypropylene glycol monomethacrylate ( Propylene oxide average added mole number = 12, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMER PP-800
43PAPE-600B (phenoxy polyethylene glycol polypropylene glycol monomethacrylate, ethylene oxide average addition mole number = 6, propylene oxide average addition mole number = 6, terminal: phenyl group): manufactured by NOF Corporation, trade name: BLEMMER 43PAPE-600B

Preparation Example 1 (Preparation of magenta ink)
84 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure was dissolved in 248 parts of methyl ethyl ketone, and 15 parts of the neutralizing agent (5N aqueous sodium hydroxide solution) (neutralization degree 60%) and 862 parts of ion-exchanged water was added to neutralize the salt-forming group, and 288 parts of quinacridone pigment (CI Pigment Violet 19, manufactured by Clariant Japan Co., Ltd., trade name: Hostaperm Red E5B02) was further added to the bead mill type. Using a disperser UAM05 (manufactured by Kotobuki Industries Co., Ltd.), the mixture was dispersed at 20 ° C. for 2 hours (dispersion medium: zirconia, temperature: 20 ° C., dispersion medium / dispersion weight ratio: 8/2, peripheral speed 15 m / s ). The obtained mixture was subjected to 10-pass dispersion treatment at a pressure of 200 MPa with a microfluidizer (trade name, manufactured by Microfluidics).
After adding 250 parts of ion-exchanged water to the obtained dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, a part of water was further removed, and a 5 μm filter (acetylcellulose membrane, outer diameter: The polymer particles containing magenta pigment having a solid content concentration of 18% are removed by filtering with a 25 mL needleless syringe (manufactured by Terumo Co., Ltd.) having a volume of 2.5 cm, manufactured by Fuji Film Co., Ltd., and removing coarse particles. An aqueous dispersion was obtained.
Next, ethylene glycol diglycidyl ether (trade name: Denacol EX-810, manufactured by Nagase ChemteX Corporation, molecular weight: 216, epoxy equivalent 113) as a crosslinking agent with respect to 80 parts of this dispersion (of which 3.3 parts of polymer) 0.10 parts, 0.45 parts of ion-exchanged water was added, and the mixture was stirred at 80 ° C. for 3 hours to obtain a magenta pigment cross-linking polymer particle dispersion having a solid content concentration of 18% (degree of cross-linking: 3% by weight). Got.

(Preparation of ink)
To 40.2 parts of the aqueous dispersion of the obtained magenta pigment cross-linking polymer particles, water-insoluble organic compound [(i) ethylene oxide adduct of phthalic acid and 2-ethylhexyl alcohol (average added mole number 4, Nippon Emulsifier Co., Ltd.) And (ii) 75 parts of a triester with an ethylene oxide adduct of trimellitic acid and lauryl alcohol (average added mole number 4, manufactured by Nippon Emulsifier Co., Ltd.). 1.3 parts were mixed and stirred to contain the water-insoluble organic compound in the polymer particles. In this mixed solution, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), 1 part of triethanolamine, Proxel XL2 (manufactured by Avicia Corporation) 0 3 parts and 39.2 parts of ion-exchanged water were mixed, and the resulting liquid mixture was attached with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Film Co., Ltd.) in a volume of 25 mL. The aqueous ink shown in Table 2 was obtained by filtering with a syringe without a needle and removing coarse particles.

Preparation Example 2 (Preparation of magenta ink)
A water-based ink shown in Table 2 was obtained in the same manner as in Preparation Example 1 except that no water-insoluble organic compound was added in Preparation Example 1.

Preparation Example 3 (Preparation of clear ink)
(Production of aqueous dispersion of crosslinked polymer particles for clear ink)
Into the reaction vessel, 137.5 parts of Liquid A (0.1% sodium hydroxide ion-exchanged water) was added and stirred (approximately 100 rpm) at room temperature under a styrene solution [styrene, divinylbenzene (100 parts of styrene). 6.4 parts by weight, pure content of divinylbenzene: 81% by weight, trade name: DVB-810, manufactured by Nippon Steel Chemical Co., Ltd., and 2,2′-azobis (2,4-dimethyl) as a polymerization initiator (Valeronitrile) (2.1 parts with respect to 100 parts of styrene, trade name: V-65, manufactured by Wako Pure Chemical Industries, Ltd.)] 11.4 parts and 35% methyl ethyl ketone solution of the polymer obtained in Production Example 1 After dripping 25.4 parts of B liquid mixed with 14.0 parts, ultrasonic dispersion is performed for 1 hour using an ultrasonic dispersion apparatus (manufactured by Nippon Seiki Seisakusho, Ultrasonic Generater Nissei Model USS-300T, 300 μA). thing The emulsion is then emulsified, heated to 75 ° C., stirred for 3 hours for polymerization, and then the organic solvent is removed and adjusted with ion-exchanged water to adjust the solid content concentration of the crosslinked polymer particles for clear ink to 10%. An aqueous dispersion (degree of crosslinking: 10% by weight) was obtained.

(Preparation of clear ink)
To 25.00 parts of the obtained dispersion of crosslinked polymer particles for clear ink, 0.4 part of the above water-insoluble organic compound, 17 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), Surfinol 465 (Nissin) 1 part of Chemical Industry Co., Ltd.), 1 part of triethanolamine, 0.3 part of Proxel XL2 (manufactured by Avicia Co., Ltd.), and 48.3 parts of ion-exchanged water were mixed, and the resulting liquid mixture was 1.2 μm. The clear ink shown in Table 2 was obtained by filtering with a 25 mL needleless syringe equipped with a filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Film Co., Ltd.) to remove coarse particles.

Preparation Example 4 (Preparation of clear ink)
Clear inks shown in Table 2 were obtained in the same manner as in Preparation Example 3 except that no water-insoluble organic compound was added in Preparation Example 3.

Examples 1-4 and Comparative Examples 1-4
As shown in Table 3, using the magenta ink obtained in Preparation Examples 1 and 2 and the clear ink obtained in Preparation Examples 3 and 4, the secondary color red (RGB value is R: 255, G: 0, B: 0) was instructed by a personal computer to evaluate ink wetting and spreading. The results are shown in Table 3.

(1) Evaluation of Wetting and Spreading of Ink Using a commercially available inkjet printer (manufactured by Seiko Epson Corporation, model number: PX-A650, piezo method), commercially available inkjet photo paper (manufactured by Seiko Epson Corporation) Glossy> Model No .: KA450PSK) was designated to print red solid [printing condition = paper type: EPSON photo paper, mode setting: photo], and printing was performed up to the second pass. In this evaluation, the dot in which the ink ejected from the magenta ink head (M head) was applied on the ink dot ejected from the yellow ink head (Y head) was evaluated.
Laser microscope (manufactured by Keyence Co., Ltd., product name: Ultra Depth) The long diameter of single dots ejected from the M head, which were laid on top of three or more connected ink dots (approximately 70 μm or more) ejected from the Y head. The shape was measured three times using a shape measuring microscope (model number: VK-8500), and the average value was obtained. The higher the numerical value, the higher the wet spreading property.
Here, the dots hit in a superimposed manner usually have an elliptical shape, and the major axis is measured. Further, the reason why the dots are superimposed on the ink connected to 3 dots or more (about 70 μm or more) is that it is considered that the dots that are applied afterward are sufficiently expanded under these conditions. If the ink hit later is overlapped by 50% or more in area with the ink hit earlier, the measurement is not affected.

  FIG. 1A is a diagram showing an ink jet recording method in which magenta ink is applied after clear ink is applied on dedicated paper, and FIG. 1B is a diagram in which dots are applied by the above method. It is an enlarged view of a paper surface. In FIG. 1B, a dot of clear ink in which three or more dots indicated by dotted lines are connected, a dot of solid ink indicated by a solid line and the spread thereof are indicated by X, and X is the major diameter of the dots of magenta ink. Indicates.

Next, with respect to the long diameter of single dots ejected from the M head, the enlargement ratio with respect to the diameter of single dots hit on the paper surface was determined. The higher the numerical value, the higher the wet spreading property. The diameter of the single dot applied to the paper surface of the magenta ink obtained in Preparation Example 1 was 23.8 μm, and the diameter of the single dot applied to the paper surface of Clear Ink obtained in Preparation Example 3 was 25.4 μm. there were. The results are shown in Table 3.
The Y head shown in Table 3 indicates a yellow ink head, and the M head indicates a magenta ink head. This indicates that printing was performed by setting the ink described in Table 3 to each ink head.

Examples 5-7 and Comparative Examples 5-6
As shown in Table 4, 45 ° image clarity was measured when overprinting was performed using the magenta ink obtained in Preparation Examples 1 and 2 and the clear ink obtained in Preparation Examples 3 and 4. The results are shown in Table 4.

(2) Evaluation of 45 ° image clarity After printing (first printing) the ink shown in Table 4 of 50% Duty on the commercially available inkjet photographic paper using the commercially available inkjet printer [printing condition = paper type: EPSON Photographic paper, mode setting: Photo], 50% duty overprinting (post-printing) was performed using the ink shown in Table 4 as another ink. After standing at 25 ° C. for 24 hours, the 45 ° image clarity is measured 3 times with a image clarity measuring device (trade name: image clarity measuring device, product number: ICM-1T, manufactured by Suga Test Instruments Co., Ltd.), and the average value is obtained. It was. The larger the value, the higher the image clarity.
Note that both the ink to be printed first and the ink to be printed later were printed using a magenta ink head (M head).

From the results shown in Table 3, in Examples 1 to 4, the ink was wet or spread later than Comparative Examples 1 to 4, and the ink containing the water-insoluble organic compound was hit afterwards. It can be seen that the ink is excellent in wet spread.
Further, from the results shown in Table 4, Examples 5 to 7 have high image clarity as compared with Comparative Examples 5 and 6, and excellent image clarity when ink containing a water-insoluble organic compound is hit first. I know that there is.

FIG. 1A is a diagram illustrating an ink jet recording method in which magenta ink is applied after clear ink dots are applied on dedicated paper, and FIG. 1B is a diagram in which dots are applied by the above method. It is an enlarged view of a paper surface.

Claims (9)

  An inkjet recording method using an ink set comprising two or more water-based inks having different compositions, wherein at least one of the water-based inks has a maximum weight (20 ° C.) that can be dissolved in 100 g of water of 5 g or less. An ink jet recording method, comprising: a water-insoluble organic compound, wherein dots of other inks are superimposed on the dots on which the ink has been previously deposited.   The ink jet recording method according to claim 1, wherein the ink that is hit first and / or the ink that is hit after overlapping includes polymer particles.   3. The ink jet recording method according to claim 1, wherein the content of the water-insoluble organic compound in the ink hit first is 0.05 to 3% by weight.   The inkjet recording method according to claim 1, wherein the water-insoluble organic compound is at least one selected from the group consisting of an ester compound, an ether compound, and a sulfonic acid amide compound.   The ink jet recording method according to claim 1, wherein the ink set comprises clear ink and colored ink.   6. The ink jet recording method according to claim 5, wherein the ink that is struck first is a clear ink, and the ink that is struck repeatedly afterward is a colored ink.   The inkjet recording method according to claim 5 or 6, wherein a clear ink contains the water-insoluble organic compound and polymer particles.   The inkjet recording method according to any one of claims 5 to 7, wherein a colored ink contains the water-insoluble organic compound, a colorant, and polymer particles.   The ink jet recording method according to any one of claims 2, 7, and 8, wherein the polymer particles are crosslinked polymer particles.

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