JP5291967B2 - Water-based ink for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous ink for ink jet recording, with excellent aging stability and discharge stability besides glossiness and mapping property. <P>SOLUTION: The aqueous ink for ink jet recording comprises a polymer particle containing a coloring agent; at least one water-insoluble organic compound selected among the group consisting of ester compounds, ether compounds and sulfonic acid amides with a maximum weight of 5g or less (except aliphatic monoester compounds) soluble in 100 g of water (20&deg;C); a 4-12C alkane polyol; and a polyalkylene glycol or an alkyl ether thereof. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an aqueous ink for inkjet recording.

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 of vinyl polymer particles or polyester polymer particles containing a colorant, and water, in order to provide a water-based ink for ink-jet recording having high print density and excellent glossiness and image clarity. Although an aqueous dispersion for inkjet recording containing an insoluble organic compound (excluding a fatty acid derivative) is disclosed, it is not satisfactory in the temporal stability of the ink.
Patent Document 3 discloses an ink-jet pigment ink in which the total content of fatty acid derivatives in the pigment ink is 1.0% by mass or less, and the pigment particles are coated with a water-insoluble polymer. It is not satisfactory in sex.
Patent Document 4 discloses an aqueous ink composition containing a pigment coated with a water-insoluble polymer, water, and a water-soluble organic compound, and further containing a plasticizer. In addition, the ink is not satisfactory in terms of stability over time.

International Publication No. 00/39226 Pamphlet JP 2007-77375 A JP 2003-147236 A JP 2007-277291 A

  An object of the present invention is to provide a water-based ink for ink-jet recording which is excellent in glossiness and image clarity, and is excellent in stability over time and ejection stability.

The present invention includes a water-based ink for inkjet recording containing a polymer particle containing a colorant and a water-insoluble organic compound containing an alkane polyol and a polyalkylene glycol or an alkyl ether thereof so that the water-insoluble organic compound is contained in the polymer particle. It has been found that the above problems can be solved by stabilizing.
That is, the present invention has a maximum weight of 5 g or less that can be dissolved in 100 g (20 ° C.) of polymer particles containing a colorant, and is selected from the group consisting of an ester compound, an ether compound, and a sulfonic acid amide compound. Provided is an aqueous ink for inkjet recording comprising at least one water-insoluble organic compound (excluding a fatty acid monoester compound), an alkane polyol having 4 to 12 carbon atoms, and a polyalkylene glycol or an alkyl ether thereof.

  According to the present invention, it is possible to provide an aqueous ink for ink-jet recording that has excellent glossiness, image clarity, and ejection stability, excellent stability over time, and little change in glossiness when printed on dedicated paper.

The water-based ink for ink-jet recording of the present invention has a maximum weight of 5 g or less that can be dissolved in polymer particles containing colorant and 100 g of water (20 ° C.), and comprises an ester compound, an ether compound, and a sulfonic acid amide compound. It contains one or more water-insoluble organic compounds selected from the group (excluding fatty acid monoester compounds), alkane polyols having 4 to 12 carbon atoms, and polyalkylene glycols or alkyl ethers thereof.
Hereinafter, each component used in the present invention will be described.

(Alkane polyol having 4 to 12 carbon atoms)
In the present invention, an alkane polyol having 4 to 12 carbon atoms (hereinafter, also simply referred to as “alkane polyol”) stabilizes a water-insoluble organic compound in polymer particles by interaction with polyalkylene glycol or an alkyl ether thereof. It is considered that the stability of the glossiness and the ejection stability are improved.
The alkane polyol used is preferably a linear or branched alkane polyol having 6 to 10 carbon atoms, more preferably 8 to 10 carbon atoms. The alkane polyol has 2 or more hydroxyl groups, preferably 2 to 6 and more preferably 2 to 4.
The molecular weight of the alkane polyol is preferably from 100 to 500, more preferably from 100 to 300.
Specific examples of the alkanediol having 4 to 12 carbon atoms include 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,3 -Butanediol, 1,2-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,2-pentanediol, 2,4-diethyl-1,5-pentanediol, 1 2,4-trimethyl-1,3-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 1,6-hexanediol, 2- Examples include ethyl-1,3-hexanediol, 1,2-hexanediol, 1,2-octanediol, 1,2-decanediol, 1,2-dodecanediol, and the like.
Specific examples of the alkanetriol having 4 to 12 carbon atoms include 1,2,6-hexanetriol, 1,2,3-butanetriol, pentanetriol, 1,2,4-butanetriol and the like.
Among these, from the viewpoint of stability over time, alkanediols having 4 to 12 carbon atoms are preferable, alkanediols having 4 to 12 carbon atoms each having a hydroxyl group at adjacent carbon atoms, more preferably 4 to 12 1,2-alkanediol is more preferable, and 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol are more preferable.

Since alkane polyol has high affinity with water-insoluble organic compounds, it is considered that alkane polyol contributes to stability in polymer particles. From this viewpoint, the absolute value of the difference in the solubility parameter (SP value) between the alkane polyol and the water-insoluble organic compound (hereinafter also simply referred to as “SP value”) is preferably 6 or less, and preferably 5 or less. Is more preferable, and it is still more preferable that it is 4.5 or less.
11-18 are preferable and, as for SP value of alkane polyol, 12-15 are more preferable.
7-12 are preferable and, as for SP value of a water-insoluble organic compound, 9-11 are more preferable.
The solubility parameter (SP value) referred to in the present specification was determined based on the following Fedors equation by the Fedors method [Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)]. The value δ [(MPa) ^1/2 ], which is obtained from the square root of the ratio of the sum of evaporation energy of atoms or atomic groups (Δei) of the chemical structure of the compound to the sum of molar volumes (Δvi).
Fedors equation: δ = (ΣΔei / ΣΔvi) ^1/2

(Polyalkylene glycol or its alkyl ether)
Polyalkylene glycol or its alkyl ether is considered to improve glossiness, stability of glossiness, and image clarity as well as ejection stability by interaction with alkane polyol. The polyalkylene glycol or alkyl ether thereof preferably has a maximum weight exceeding 5 g that can be dissolved in 100 g of water (20 ° C.). Polyalkylene glycols include polyethylene glycol, polypropylene glycol, poly (ethylene glycol / propylene glycol) [ethylene glycol and propylene glycol are randomly bonded], or polyethylene glycol / polypropylene glycol [polyethylene glycol and polypropylene glycol are block bonded. Etc.].
From the above viewpoint, the polyalkylene glycol or its alkyl ether is preferably polyethylene glycol represented by the following general formula (1) or its alkyl ether.
^{_{R 11 -O- (CH 2 CH 2}} O) n-H (1)
(In the formula, R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and n represents an average added mole number and is a number of 5 to 60.)
R ¹¹ is preferably a hydrogen atom or an alkyl group, and examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, a propyl group, a butyl group, a t-butyl group, an isobutyl group, and a pentyl group. In these, a hydrogen atom is preferable from a viewpoint of discharge stability.
n is an average addition mole number, 10-40 are preferable and 10-30 are still more preferable.
From the viewpoint of ejection stability, the molecular weight of the polyalkylene glycol or its alkyl ether is preferably 500 to 5000, and more preferably 500 to 3000.
Polyalkylene glycol or its alkyl ether can be used alone or in admixture of two or more at any ratio, and polyalkylene glycol and its alkyl ether can be used in combination.

(Water-insoluble organic compound)
In the present invention, the maximum weight that can be dissolved in 100 g (20 ° C.) of water is 5 g or less, and one or more water-insoluble organic compounds selected from the group consisting of ester compounds, ether compounds, and sulfonic acid amide compounds ( Hereinafter, simply referred to as “water-insoluble organic compound”) is used.
At least a part of the water-insoluble organic compound is contained in the polymer particles. As a result, the fusibility of the polymer particles ejected from the nozzles of the ink jet recording apparatus is enhanced, the polymer particles are uniformly diffused on the special paper, and the printing surface becomes smooth, thereby improving the gloss of the printed matter. I think that.
The fatty acid monoester compound is not included in the water-insoluble organic compound used in the present invention because the fatty acid monoester compound does not exhibit the effects described above. Here, the fatty acid monoester compound refers to a fatty acid monoester compound produced from a monovalent fatty acid which is a saturated or unsaturated aliphatic carboxylic acid and a monohydric alcohol.
More specifically, the fatty acid monoester refers to a monoester compound produced from a saturated or unsaturated aliphatic carboxylic acid having 8 to 22 carbon atoms and an alcohol, such as isotridecyl myristate, methyl stearate, methyl oleate. , Methyl palmitate, methyl behenate and the like. However, these fatty acid monoester compounds may be contained in the aqueous dispersion of the present invention as long as the object of the present invention is not impaired.

The water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, more preferably a molecular weight of 100 to 1,000, from the viewpoint of improving the glossiness and image clarity of the ink.
The maximum weight that can be dissolved in 100 g of water (20 ° C.) is 5 g or less, preferably 3 g or less, more preferably 1 g or less.
In order to improve the flexibility of the polymer, the water-insoluble organic compound preferably has a LogP value of −1 to 11, more preferably 1 to 9, still more preferably 1.5 to 8, and particularly preferably 2 to 7. preferable.
In addition, from the viewpoint of the interaction between the water-insoluble organic compound and the polymer particles, the value of [[Log P value of the water-insoluble organic compound] − [Log P value of the polymer]] is preferably −4 to 8, It is more preferably 2 to 6, more preferably −1.5 to 5, and particularly preferably −1 to 4.
Here, “Log P value” means the logarithmic value of the 1-octanol / water partition coefficient of water-insoluble organic compounds, 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. 84: 83-92 .). 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, or a sulfonic acid amide compound in order to make it easy to be contained in the polymer particles. Ester or ether compound having two or more ether bonds, and / or (g) one or more ester or ether bonds in the molecule, carboxy group, sulfate group, sulfonic acid group, phosphonic acid group, phosphoric acid residue An ester or ether compound having at least one functional group selected from the group consisting of a group, a carbonyl group, an epoxy group and a hydroxyl group is more preferred. (F) The ester or ether bond of the compound is preferably 2 to 3, and may have an ester bond and an ether bond. (G) As for the ester or ether bond of a compound, 1-3 are preferable. The number of functional groups is preferably 1 to 3. A phosphoric acid residue means the remaining phosphoric acid group in which a part of phosphoric acid was esterified.
Among the ester compounds, an ester obtained from a monovalent carboxylic acid or a salt thereof and a polyhydric alcohol, an ester obtained from a polyvalent acid (polyvalent carboxylic acid, phosphoric acid) or a salt thereof and a monohydric alcohol is preferred, and aliphatic. Or it is more preferable to have two aromatic carboxylic acid ester groups or three phosphoric acid ester groups. Examples of the salt include alkali metal salts, alkanolamine salts, ammonium salts and the like. Of the ether compounds, polyhydric alcohol ether compounds are preferred.

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, Straight chain 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) 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 C2-C12 polyhydric alcohols 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) Oxyacid ester, (6) glycol ester, (7) epoxy ester, (8) sulfonamide, (9) polyester, (10) glyceryl alkyl ether, (11) glyceryl alkyl ester, (12) glycol alkyl ether, ( 13) glycol alkyl ester, (14) ether or ester of trimethylolpropane, (15) ether or ester of pentaerythritol, and the like.
Among these, from the viewpoints of image clarity and gloss, the compounds (1) to (5), (8) and (10) are preferred, and are aliphatic di- or tricarboxylic acid esters, and (2) aromatic carboxylic acids. It is preferably at least one selected from the group consisting of an ester, (3) cycloalkane (ken) carboxylic acid ester, and (4) phosphoric acid ester, an aliphatic dicarboxylic acid ester, an aromatic di- or tricarboxylic acid ester, a cycloester It is most preferably at least one selected from the group consisting of alkane (ken) carboxylic acid esters and phosphate esters, and most preferably a compound represented by the following general formula (1).

  (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 (2).

(.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 gloss 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, still more 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, EO average addition moles m and n = 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 -Ethyl hexyl, 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 (3).

(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 aromatic carboxylate 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 Phthalate 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, carbon number 3 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) More specifically, the cycloalkane (ken) carboxylic acid ester is more preferably a cyclohexane (cene) carboxylic acid ester represented by the following formula (4). Examples of the cycloalkane (ken) group include 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 (5).

(In the formula, R ¹ and R ² have the same meaning as described above and may be the same or different.)
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 A phosphate etc. are mentioned. 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) The oxyacid ester is preferably a compound represented by the following formula (6).

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above. R ¹ and R ² may be the same or different.)
Specific examples of the oxyester include triethyl acetylcitrate, tributyl acetylcitrate, methyl acetylricinoleate and the like.

  (6) The glycol ester is preferably a compound represented by the following formula (7).

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above. R ¹ and R ² may be the same or different.)
Specific examples of the glycol ester include diethylene glycol dibenzoate and triethylene glycol di (2-ethylhexoate).

  (7) The epoxy ester is preferably a compound represented by the following formula (8).

(In the formula, R ¹ has the same meaning as described above. R ⁴ and R ⁵ each independently represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and R ⁶ represents an alkanediyloxy group having 1 to ⁶ carbon atoms. Show.)
Specific examples of the epoxy ester include butyl epoxy stearate and octyl epoxy stearate.

  (8) The sulfonamide is preferably a compound represented by the following formula (9).

(In the formula, R ¹ and R ² have the same meaning as described above and may be the same or different.)
Specific examples of the sulfonamide include o- and p-toluenesulfonamide, N-butylbenzenesulfonamide and the like.

  (9) The polyester is preferably a compound represented by the following formula (10).

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above and may be the same or different. P represents a number of 1 to 18, preferably 1 to 10.)
Specific examples of the 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. The alkyl group has 8 to 30 carbon atoms, preferably 8 to 22 carbon atoms, and more preferably 8 to 14 carbon atoms. Examples of the alkyl group include 2-ethylhexyl, (iso) octyl, (iso) decyl, (iso) dodecyl, (iso) myristyl, (iso) cetyl, (iso) stearyl, and (iso) behenyl groups.
There is no restriction | limiting in particular about the position of an alkyl group, Either 1-alkyl glyceryl monoether and 2-alkyl glyceryl monoether may be sufficient.

(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 of the compound (12) include ethylene glycol and neopentyl glycol, and the alkyl group is a straight chain having 1 to 22 carbon atoms, preferably 6 to 20 carbon atoms, more preferably 8 to 18 carbon atoms. Or a branched alkyl group is mentioned.

(Coloring agent)
The colorant used in the present invention is not particularly limited, and pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.) can be used, but water resistance, dispersion stability and resistance From the viewpoint of abrasion, pigments and hydrophobic dyes are preferable. Among them, it is preferable to use a pigment in order to express the high weather resistance which has been recently demanded.
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. In particular, from the viewpoints of bleeding resistance, water resistance, and the like, it is preferable to include a pigment and / or a hydrophobic dye in the polymer particles.
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 hydrophobic dye is not particularly limited as long as it can be contained in the polymer particles. 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 containing colorant)
In the present invention, the polymer particles are used to improve glossiness by interaction with a water-insoluble organic compound. Moreover, in order to disperse | distribute a coloring agent stably, a coloring agent is contained in a polymer particle.
Examples of the polymer used for the polymer particles include polyester, polyurethane, and vinyl polymer. From the viewpoint of dispersion stability, a vinyl polymer obtained by addition polymerization of a vinyl monomer (vinyl compound, vinylidene compound, vinylene compound) is used. preferable.
The polymer is preferably a water-insoluble polymer in order to easily contain a water-insoluble organic compound. 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.

(polymer)
The polymer used in the present invention includes a structural unit derived from the salt-forming group-containing monomer (a) (hereinafter also referred to as “component (a)”), a structural unit derived from the (meth) acrylate compound (b), and specifically Includes a structural unit derived from a (meth) acrylic acid ester-based macromer (b) (hereinafter also referred to as “component (b)”), an alkyl ester or aryl ester (c) of (meth) acrylic acid (hereinafter “(c)”) From the structural unit derived from the structural unit derived from the component unit) and the alkanediyl oxide ester (d) of (meth) acrylic acid represented by the following general formula (11) (hereinafter also referred to as “component (d)”) It is preferable from the viewpoint of ejection stability that it consists essentially of one or more structural units selected from the group consisting of: In particular, when the water-based ink of the present invention is used for a thermal ink jet recording apparatus, it is preferable because it can reduce the adhesion of a polymer to an ink discharge nozzle.
Here, “essentially” means a range that does not impair the effects of the present invention, preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.1% or less, derived from other monomer components. It means that it may have a structural unit, and it is preferable not to have a structural unit derived from another monomer component.
CH ₂ = C (R ¹² ) COO (R ¹³ O) _q R ¹⁴ (11)
(In the formula, R ¹² represents a hydrogen atom or a methyl group, R ¹³ represents a hydrocarbon group having 2 or 3 carbon atoms, R ¹⁴ represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 22 carbon atoms, q represents the average number of moles added and is a number from 1 to 60.)
This polymer is preferably obtained by copolymerizing a monomer mixture containing the component (a) and the component (b), the component (c) and / or the component (d) (hereinafter also referred to as “monomer mixture”).

(A) The salt-forming group-containing monomer is used from the viewpoint of enhancing the dispersion 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 a cationic monomer and an anionic monomer. Examples thereof include those described in paragraph [0022] of JP-A-9-286939.
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. Unsaturated phosphoric acid monomers include vinyl phosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyciethyl phosphate Etc.
Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of dispersion stability and ejection stability.

The (b) (meth) acrylic acid ester-based macromer (hereinafter, also simply referred to as “(b) macromer”) is used from the viewpoint of enhancing the dispersion stability of the polymer particles when the polymer particles contain a colorant. it can. The (meth) acrylic acid ester-based macromer means one having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group present at one end of the macromer.
(B) 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 the macromers (b), from the viewpoint of dispersion stability of polymer particles, styrene macromers and aromatic group-containing (meth) acrylate macromers having the polymerizable functional group at one end are exemplified.
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.
Moreover, as another monomer copolymerized, the acrylonitrile etc. which are represented by following formula (12) are preferable.

(In the formula, x and y represent the average added mole number, and x / y = 6/4 to 10/0.)
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% from the viewpoint of increasing the affinity with the colorant. % Or more, 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 (13).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _{t -Si (CH 3) 3 (} 13)
(In the formula, t represents a number of 8 to 40).
(B) Styrenic macromers that are commercially available as macromers include, for example, trade names of Toa Gosei Co., Ltd., AS-6 (S), AN-6 (S), HS-6 (S), and the like. It is done.

(C) Alkyl ester or aryl ester of (meth) acrylic acid can be used from the viewpoint of enhancing storage stability.
(C) The alkyl ester of (meth) acrylic acid includes (meth) acrylic acid ester having an alkyl group having 1 to 22 carbon atoms, preferably 1 to 18 carbon atoms, more preferably 1 to 12 carbon atoms. .
Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (meth) acrylic acid (iso or tert-) butyl, (meth) acrylic acid (iso ) Amyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid (iso) octyl, (meth) acrylic acid (iso) decyl, (meth) acrylic acid (iso) dodecyl, ( Examples include (meth) acrylic acid (iso) stearyl.
Specific examples of the (meth) acrylic acid aryl ester include 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, such as phenyl (meth) acrylate, benzyl (meth) acrylate, and phenoxyethyl (meth) acrylate. More preferable examples include aryl groups having 6 to 12 carbon atoms, arylalkyl groups, and (meth) acrylic acid aryl esters which may have an alkoxy group.
In the present specification, “(iso or tert-)” and “(iso)” mean that both of these groups are present and not present, and these groups are present. If not, it indicates normal. “(Meth) acrylic acid” refers to acrylic acid and / or methacrylic acid.
Among the above, (meth) acrylic acid aryl ester is preferable, and benzyl methacrylate is more preferable from the viewpoint of increasing adsorption power to the pigment and obtaining higher storage stability and printing density.

(D) Alkanediyl oxide ester of (meth) acrylic acid The polymer used in the present invention assists the stability after the pigment is contained in the polymer, and from the viewpoint of enhancing the ejection stability, the following general formula ( 11) The structural unit derived from alkanediyl oxide ester (d) of (meth) acrylic acid represented by 11).
CH ₂ = C (R ¹² ) COO (R ¹³ O) _q R ¹⁴ (11)
(In the formula, R ¹² represents a hydrogen atom or a methyl group, R ¹³ represents a hydrocarbon group having 2 or 3 carbon atoms, R ¹⁴ represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 22 carbon atoms, q represents the average number of moles added and is a number from 1 to 60.)
Specific examples of R ¹³ include an ethylene group, a trimethylene group, or a propane-1,2-diyl group. q means the average number of added moles, preferably 7 to 30, and more preferably 8 to 23. When q is 2 or more, R ¹³ may be the same or different and may be either block addition or random addition.
R ¹⁴ is preferably a linear or branched alkyl group having 3 to 22 carbon atoms, more preferably 8 to 18 carbon atoms. Specifically, methyl group, ethyl group, (iso) propyl group, (iso or tert-) butyl group, (iso) amyl group, hexyl group, 2-ethylhexyl group, (iso) octyl group, (iso) decyl Group, (iso) dodecyl group, (iso) stearyl group, behenyl group and the like.
However, when the average added mole number q is 4 or less, R ¹⁴ is preferably a linear or branched alkyl group having 3 to 22 carbon atoms from the viewpoint of ejection stability and storage stability.

As a suitable example of the component (d), polyethylene glycol having an alkyl group at the terminal (n = 2 to 30, n represents the average number of added moles of alkanediyloxy group; the same shall apply hereinafter) (meth) acrylate, at the terminal Polypropylene glycol having an alkyl group (n = 2 to 30) (meth) acrylate, poly (ethylene glycol (n = 1 to 15) / propylene glycol (n = 1 to 15)) (meth) acrylate having an alkyl group at the terminal Etc.
Particularly preferred specific examples include 2-ethylhexyloxypolyethylene glycol (n = 4) methacrylate, 2-ethylhexyloxypolyethylene glycol (n = 9) methacrylate, methoxypolyethylene glycol (n = 9) methacrylate and the like.
Specific examples of the commercially available component (d) include monofunctional acrylate monomers (NK esters) EH-4E, EH-9E, M-90G from Shin-Nakamura Chemical Co., Ltd. Mer series, 50PEP-300, 50POEP-800B and the like.
The components (a) to (d) can be used alone or in admixture of two or more.

The content of the components (a) to (d) in the monomer mixture at the time of polymer production (content as an unneutralized amount; the same applies hereinafter) or derived from the components (a) to (d) in the water-insoluble polymer The content of the structural unit is as follows.
The content of 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 dispersion 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 viewpoints of glossiness and image clarity.
The content of component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The total content of [component (a) + component (d)] in the monomer mixture is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, from the viewpoint of dispersion stability of the resulting dispersion. is there. The total content of [component (b) + component (c)] is preferably 30 to 90% by weight, more preferably 40 to 80% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
Further, the weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.02 to 0.8, more preferably 0.03, from the viewpoint of glossiness and image clarity. It is -0.6, More preferably, it is 0.05-0.5.

(Manufacture of polymers)
The polymer used in the present invention is produced by copolymerizing the 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 is preferably from 5,000 to 500,000, more preferably from 10,000 to 400,000, and even more preferably from 10,000 to 300,000, from the viewpoint of printing density, glossiness, and dispersion stability of the colorant. 20,000 to 300,000 is particularly preferable. In addition, the weight average molecular weight of a polymer is measured by the method shown in an Example.
When the polymer has (a) a salt-forming group derived from a salt-forming group-containing monomer, the polymer is used after being 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
Moreover, when a salt formation group is a cationic group, it can obtain | require by a 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.

(Manufacture of water-based ink for inkjet recording)
Although there is no limitation in particular in the manufacturing method of the water-based ink for inkjet recording of this invention, For example, it can obtain by following process (1)-(3).
Step (1): Step of obtaining a dispersion of polymer particles containing a colorant by dispersing a mixture containing a polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent Step (2): Step (1) Step of removing the organic solvent from the obtained dispersion to obtain an aqueous dispersion of polymer particles containing a colorant Step (3): Step (2) The obtained polymer containing a colorant A step of mixing an aqueous dispersion of particles, a water-insoluble organic compound, an alkane polyol, and a polyalkylene glycol or an alkyl ether thereof.

In step (1), first, the polymer is dissolved in an organic solvent, and the resulting organic solvent solution is mixed with a colorant, water, and if necessary, a neutralizing agent, a surfactant, and the like. A method for obtaining an oil-in-water 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, but the degree of neutralization is not particularly limited. 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 water-insoluble 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 maximum weight that can be dissolved in 100 g of water (20 ° C.) is preferably 5 g or more, more preferably 10 g or more, more specifically preferably 5 to 80 g, and more preferably 10 to 50 g. In particular, methyl ethyl ketone and methyl isobutyl ketone are preferable.

There is no restriction | limiting in particular in the dispersion method of the mixture in the said process (1). Although the average particle size of the polymer particles can be atomized until the desired particle size is obtained without pre-dispersing, it is preferably pre-dispersed using a commonly used mixing and stirring device such as a media-type disperser. After that, it is preferable to control the average particle size of the polymer particles to be a desired particle size by applying a shear stress to the dispersion. The temperature in the dispersion in the step (1) is preferably 5 to 50 ° C, more preferably 10 to 35 ° C, and the dispersion time is preferably 1 to 30 hours, more preferably 2 to 25 hours.
Examples of means for applying the shear stress of this dispersion include a bead mill, a high-pressure homogenizer [Izumi Food Machinery Co., Ltd., trade name], a mini-lab type 8.3H type (Rannie Co., trade name) represented by a homovalve type high-pressure homogenizer, micro Examples thereof include a chamber type high-pressure homogenizer such as a fluidizer [Microfluidics, trade name] and a nanomizer [Nanomizer, trade name]. A plurality of these devices can be combined. Among these, a high-pressure homogenizer is preferable from the viewpoint of reducing the particle size of the pigment.

In the step (2), an aqueous dispersion of polymer particles containing a colorant can be obtained by distilling off the organic solvent from the obtained dispersion by a known method to form an aqueous system. 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. 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 water dispersion obtained in the step (2), the water-insoluble organic compound, the alkane polyol, and the polyalkylene glycol or the alkyl ether thereof may be mixed. Preferably, the water dispersion obtained in the step (2) and the water-insoluble organic compound are mixed and dispersed, and then the alkane polyol and polyalkylene glycol or alkyl ether thereof are mixed. Thus, an aqueous dispersion of polymer particles containing a water-insoluble organic compound and a colorant, in which at least part of the water-insoluble organic compound is contained in the polymer particles, an alkane polyol and a polyalkylene glycol or an alkyl ether thereof. As a result, the aqueous dispersion can be stabilized and the ejection stability can be improved. The alkane polyol, polyalkylene glycol or alkyl ether thereof may be present together with the water-insoluble organic compound in the polymer particles, or may be present in the aqueous dispersion.
The means for performing the distributed processing is the same as in the above step (2). An ultrasonic homogenizer can also be used. For example, as the ultrasonic homogenizer, those having a frequency of 20 to 2000 kHz and a wattage per liter of the total reaction liquid amount of preferably 20 to 1000 W, more preferably 50 to 800 W are desirable. Such an ultrasonic disperser is commercially available from Nippon Seiki Seisakusho, Alex Co., Ltd. A plurality of these devices can be combined. 5-50 degreeC is preferable and, as for the temperature in dispersion | distribution of a process (3), 10-35 degreeC is still more preferable.

A commonly used wetting agent, penetrating agent, dispersant, viscosity modifier, antifoaming agent, antifungal agent, rust preventive agent and the like may be added to the water-based ink for inkjet recording of the present invention.
The average particle diameter of the polymer particles in the obtained water-based ink is preferably 0.01 to 0.5 μm, more preferably 0.03 to 0.3 μm, from the viewpoint of preventing clogging of the nozzles of the printer and dispersion stability. Especially preferably, it is 0.05-0.2 micrometer. The average particle diameter can be measured with a laser particle analysis system ELS-8000 (cumulant analysis) manufactured by Otsuka Electronics Co., Ltd. The measurement conditions are a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and an integration count of 100. The refractive index of water (1.333) is input as the refractive index of the dispersion solvent. The measurement concentration is usually about 5 × 10 ⁻³ wt%.

(Water-based ink for inkjet recording)
The content of each component in the water-based ink for ink-jet recording of the present invention and the ratio thereof are as follows.
In the water-based ink, the content of the water-insoluble organic compound is preferably 0.1 to 5% by weight, more preferably 0.15 to 3% by weight, and particularly preferably 0.2 to 2% by weight from the viewpoint of improving glossiness. preferable.
The content of the polymer particles in the water-based ink (the solid content excluding the water-insoluble organic compound and the colorant; the same shall apply hereinafter) is preferably from 0.25 to 10% by weight from the viewpoint of printing density and glossiness. 5-8 weight% is still more preferable, and 0.5-5 weight% is especially preferable.
In the water-based ink, the content of the colorant is preferably 1 to 15% by weight, more preferably 2 to 10% by weight, and particularly preferably 2 to 8% by weight from the viewpoint of printing density.
In the water-based ink, the content of the alkane polyol is preferably 0.2 to 10% by weight, more preferably 0.3 to 8% by weight, and more preferably 0.5 to 5% by weight from the viewpoint of glossiness due to the improvement of stability over time. Is particularly preferred.
In the water-based ink, the content of polyalkylene glycol or alkyl ether thereof is preferably 0.2 to 10% by weight, more preferably 0.5 to 8% by weight, from the viewpoint of ejection stability and gloss, and 1 to 6 Weight percent is particularly preferred.

The weight ratio of [water-insoluble organic compound / alkane polyol] is preferably 3/1 to 1/5, more preferably 1/1 to 1/5, and more preferably 1/2 to 1/5 from the viewpoints of stability over time and gloss improvement. 1/4 is more preferable.
The weight ratio of [alkane polyol / polyalkylene glycol and its alkyl ether] is preferably 3/1 to 1/5, more preferably 1/1 to 1/5 from the viewpoints of stability over time and gloss. More preferably, 1/1 to 1/3 is still more preferable.
The weight ratio of [water-insoluble organic compound / polymer particles] is preferably 1/50 to 1/1, more preferably 1/30 to 1/1, and more preferably 1/10 to 1/1 from the viewpoint of improving glossiness. Is more preferable.
The weight ratio of [water-insoluble organic compound / colorant] is preferably 1/40 to 5/1, more preferably 1/30 to 1/1, from the viewpoint of gloss.
The weight ratio of [polymer particles / colorant] is preferably 10/90 to 75/25, more preferably 20/80 to 50/50, from the viewpoints of dispersion stability of the polymer particles and printing density.
The water content in the water-based ink of the present invention is preferably 30 to 90% by weight, more preferably 40 to 80% by weight.
The surface tension (25 ° C.) of the water-based ink of the present invention is preferably 20 to 35 mN / m, more preferably 25 to 35 mN / m, from the viewpoint of ensuring good discharge properties from the ink nozzle.
In addition, the viscosity (20 ° C.) of the water-based ink is preferably 2 to 12 mPa · s, and more preferably 2.5 to 10 mPa · s in order to maintain good ejection properties.
The ink jet recording system used in the ink of the present invention is preferably a thermal ink jet recording apparatus from the viewpoints of excellent glossiness and image clarity, and excellent temporal stability and ejection stability.

In the following production examples, examples and comparative examples, “parts” and “%” are “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 each monomer shown in Table 1 were mixed and thoroughly replaced with nitrogen gas. A mixed solution was obtained.
On the other hand, the remaining 90% of the monomers shown in Table 1 were charged into a 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-dimethyl) were added. Valeronitrile)) 1.2 parts were added and mixed, and nitrogen gas substitution was sufficiently performed 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 shown below. The results are shown in Table 1.
(Measurement of weight average molecular weight of polymer)
Gel chromatography method using a N, N-dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent [GPC apparatus (HLC-8120GPC) manufactured by Tosoh Corporation, 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.
(B) Styrene macromer, manufactured by Toa Gosei Co., Ltd., trade name: AS-6 (S), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group (d) PP-800
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 12, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMMER PP-800
(E) 50POEP-800B
Octoxy polyethylene glycol polypropylene glycol monomethacrylate (average added mole number of ethylene oxide = 8, average added mole number of propylene oxide = 6, terminal: 2-ethylhexyl group): manufactured by NOF Corporation, trade name: BLEMMER 50POEP-800B

Synthesis Example 1 (Synthesis of water-insoluble organic compound)
In a reaction vessel, 100 parts of phthalic anhydride, 433 parts of an ethylene oxide 4 mol adduct of 2-ethylhexyl alcohol (manufactured by Nippon Emulsifier Co., Ltd .: New Coal 1004) and 0.5 parts of tetraisopropoxy titanate are mixed. After sufficient nitrogen gas replacement, the temperature was raised to 220 ° C. to carry out an esterification reaction. Further, the esterification reaction is completed by carrying out a reduced pressure reaction at 6.67 × 10 ³ Pa at the same temperature, and an excess of alcohol is distilled off to distill off the excess alcohol and add 4 moles of ethylene oxide of phthalic acid and 2-ethylhexyl alcohol. The water-insoluble organic compound A of the diester was obtained. The SP value of the water-insoluble organic compound A determined from the Fedors equation was 9.4.

Synthesis Example 2 (Synthesis of water-insoluble organic compound)
Synthesis Example 1 except that 433 parts of ethylene oxide 4 mole adduct of lauryl alcohol (manufactured by Kao Corporation: Emulgen 104P) was used instead of 433 parts of ethylene oxide 4 mole adduct of 2-ethylhexyl alcohol in Synthesis Example 1. In the same manner as in No. 1, a water-insoluble organic compound B of diester of phthalic acid and 4-ethylhexyl alcohol ethylene oxide 4 mol adduct was obtained. The SP value of the water-insoluble organic compound B determined from the Fedors equation was 9.3.

Production Example 2 (Production of aqueous dispersion of polymer particles containing pigment)
25 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and 6.7 parts of a neutralizing agent (5N aqueous sodium hydroxide solution) was contained therein (neutralization degree 75%). ) And 230 parts of ion-exchanged water to neutralize the salt-forming groups, and further 75 parts of a diazo pigment (CI Pigment Yellow 74, manufactured by Sanyo Dye Co., Ltd., trade name: FY7413) were added. Dispersion treatment was performed for 2 hours at a peripheral speed of 15 m / s using Picomill (trade name, dispersion medium: zirconia, temperature: 20 ° C., dispersion medium / dispersion weight ratio: 8/2). The obtained mixture was subjected to 10-pass dispersion treatment with a microfluidizer (trade name, manufactured by Microfluidics) at a pressure of 180 MPa.
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: Water of a pigment-containing polymer particle having a solid content concentration of 20% by filtering with a 25 mL needleless syringe (manufactured by Terumo Co., Ltd.) attached with 2.5 cm, manufactured by Fuji Film Co., Ltd., and removing coarse particles. A dispersion was obtained.

Example 1
(Manufacture of aqueous dispersion for inkjet recording)
Production Example 1 80 parts of an aqueous dispersion of pigment-containing polymer particles obtained and 2 parts of the water-insoluble organic compound A obtained in Synthesis Example 1 were mixed, and an ultrasonic homogenizer US-300T (manufactured by Nippon Seiki Seisakusho Co., Ltd.) was used. A water dispersion (water-insoluble organic compound-containing water dispersion) containing a water-insoluble organic compound and pigment-containing polymer particles was obtained by treatment with V-LEVEL 200 μA for 10 minutes.
(Manufacture of water-based ink)
Water-insoluble organic compound-containing aqueous dispersion 41.0 parts, 1,2-hexanediol 3.0 parts, glycerin 9.0 parts, ethylene glycol 6.0 parts, polyethylene glycol (average molecular weight 1000) 4.0 parts, acetylinol 1.0 part of EH (acetylene glycol ethylene oxide adduct, manufactured by Kawaken Fine Chemical Co., Ltd.) and 36.0 parts of ion-exchanged water were mixed, and the resulting liquid mixture was added to a 1.2 μm filter (acetylcellulose membrane, outer diameter). : 2.5 cm, manufactured by Fuji Film Co., Ltd.) and filtered with a 25 mL needleless syringe to remove coarse particles to obtain a water-based ink.

Example 2
A water-based ink was obtained in the same manner as in Example 1 except that the water-insoluble organic compound B was used instead of the water-insoluble organic compound A in Example 1.

Example 3
A water-based ink was obtained in the same manner as in Example 1 except that 1,2-pentanediol was used in place of 1,2-hexanediol.

Comparative Example 1
In Example 1, a water-based ink was obtained in the same manner as in Example 1 except that 19.0 parts of ion-exchanged water was used without using 1,2-hexanediol.
Comparative Example 2
In Example 1, a water-based ink was obtained in the same manner as in Example 1 except that polyethylene glycol was not used and 40.0 parts of ion-exchanged water was used.

Next, the glossiness, image clarity, and ejection stability of the water-based inks obtained in Examples and Comparative Examples were evaluated by the following methods. The results are shown in Table 2.
(1) Evaluation of Glossiness After preparing the water-based inks obtained in the examples and comparative examples, the ink after storage for 1 hour at room temperature and the ink after storage for 3 days at room temperature are commercially available from Canon Inc. Using a system ink jet printer (model number: PIXUS560i), solid printing is performed on commercially available inkjet photo paper (professional photo paper, model number: PR101A4, manufactured by Canon Inc.) [printing condition = paper type: professional photo paper, mode setting: standard. ] After standing at 25 ° C. for 24 hours, the gloss value of 20 ° was measured five times with a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: HANDY GLOSSMETER, product number: PG-1), and the average value was obtained. .
The change rate of the glossiness of the ink after storage for 3 days at room temperature relative to the glossiness of the ink after storage for 1 hour at room temperature was determined by the following formula and expressed as an absolute value.
Gloss change rate (%) = [(Glossiness after storage for 3 days−Glossiness after storage for 1 hour) / Glossiness after storage for 1 hour] × 100

(2) Evaluation of image clarity Using the printer, solid printing was performed on the commercially available inkjet photographic paper, and after standing at 25 ° C for 24 hours, the image clarity C value (comb width 2.0 mm) of 45 ° was measured. The average value was obtained by measuring three times with a measuring instrument (trade name: touch panel image clarity measuring instrument, product number: ICM-IT, manufactured by Suga Test Instruments Co., Ltd.).
The image clarity is to measure the sharpness or distortion when the image is reflected on the printed matter. When the numerical value is larger, the reflected image is clearer and less distorted, and the reflected image looks natural.

(3) Evaluation of ejection stability After printing test with the printer, cleaning is performed, left in a constant temperature bath at 40 ° C for 1 day, then returned to room temperature environment, and fine-mode paper (manufactured by Canon Inc.) is used in fine mode. 100 sheets were printed in the (high-speed printing mode), and the printed state of the 100th sheet was visually observed.
〔Evaluation criteria〕
○: The printed matter does not have “Nuke” or “Bend”.
Δ: “Nuke” or “bend” in the printed matter.
×: “Nuke” and “bend” are both present on the printed matter.
Here, “Nuke” refers to the case where there are nozzles that have not ejected ink and thick white streaks are present.

  From Table 2, the water-based inks of Examples 1 to 3 are superior to the water-based inks of Comparative Examples 1 and 2 in terms of gloss, image clarity, and ejection stability, and the ink after storage for 1 hour at room temperature. It can be seen that there is little change in gloss when printed on special paper with the ink after storage for 3 days, and the stability over time is excellent.

Claims (7)

One or more water-insoluble polymers selected from the group consisting of an ester compound, an ether compound, and a sulfonic acid amide compound having a maximum weight of 5 g or less that can be dissolved in 100 g (20 ° C.) of polymer particles containing a colorant. An aqueous ink for ink jet recording comprising an organic compound (excluding a fatty acid monoester compound), an alkane polyol having 4 to 12 carbon atoms , and a polyalkylene glycol or an alkyl ether thereof, wherein the polyalkylene glycol or the alkyl ether thereof is A water-based ink for ink jet recording, which is a compound represented by the following general formula (1), and the molecular weight of polyalkylene glycol or alkyl ether thereof is 500 to 3,000 .
^{_{R 11 -O- (CH 2 CH 2}} O) n-H (1)
(In the formula, R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and n represents an average added mole number and is a number of 5 to 60.)   The water-insoluble organic compound comprises (f) an ester or ether compound having two or more ester or ether bonds in the molecule, and / or (g) one or more ester or ether bonds in the molecule, The inkjet according to claim 1, which is an ester or ether compound having at least one functional group selected from the group consisting of a group, a sulfonic acid group, a phosphoric acid residue, a carbonyl group, an epoxy group and a hydroxyl group. Water-based ink for recording. The aqueous ink for inkjet recording according to claim 1 or 2 , wherein an absolute value of a difference in solubility parameter (SP value) between the water-insoluble organic compound and the alkane polyol is 6 or less. The water-based ink for inkjet recording according to any one of claims 1 to 3 , wherein a weight ratio of the water-insoluble organic compound to the alkane polyol (water-insoluble organic compound / alkane polyol) is 3/1 to 1/5. . An aqueous dispersion of polymer particles containing a colorant and a maximum weight that can be dissolved in 100 g (20 ° C.) of water is 5 g or less, and is selected from the group consisting of an ester compound, an ether compound, and a sulfonic acid amide compound followed by dispersing the seeds more water-insoluble organic compound, and water dispersion obtained, and an alkane polyol having 4 to 12 carbon atoms, is mixed with a polyalkylene glycol or an alkyl ether thereof of claim 1-4 Any of the water-based inks for ink-jet recording. The aqueous ink for inkjet recording according to any one of claims 1 to 5, wherein an absolute value of a difference in solubility parameter (SP value) between the water-insoluble organic compound and the alkane polyol is 4.5 or less. The aqueous ink for inkjet recording according to any one of claims 1 to 6, wherein the alkane polyol is an alkane polyol having 6 to 10 carbon atoms.