JP2006176623A - Water-based ink for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink for inkjet recording simultaneously satisfying excellent gloss properties and fixing properties at high levels when printed on an exclusive paper sheet while attaining a satisfactorily high printing density when printed on a plain paper sheet, and an aqueous dispersion for inkjet recording used for the manufacture of the ink. <P>SOLUTION: The aqueous dispersion for inkjet recording comprises an aqueous dispersion of a water-insoluble vinyl polymer particle containing a quinacridone pigment (A) and a pigment derivative (B) obtained by introducing an acidic group into an organic pigment, where the water-insoluble vinyl polymer has a constituting unit represented by formula (1) (wherein R<SP>1</SP>is a hydrogen atom or a methyl group; and R<SP>2</SP>is, optionally substituent-bearing, a 7-22C arylalkyl group or a 6-22C aryl group). The water-based ink comprises the aqueous dispersion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aqueous ink for inkjet recording. Specifically, an inkjet recording water-based ink that can exhibit high gloss and fixing properties when printed on special paper while satisfying a high print density when printed on plain paper, and inkjet recording water used for the ink Concerning the dispersion.

The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording member and attaching them. This method is easily spread at a full color and is inexpensive, and can be used as a recording member, and can be used as a recording member.
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, and a graft polymer using a macromer as a vinyl polymer in order to impart a high printing density.
Patent Document 2 discloses an organic pigment mass having good dispersion stability, which contains an organic pigment such as a quinacridone pigment, a sulfonated organic pigment, a monovalent inorganic counterion and a divalent or higher inorganic counterion. ing. It is described that the water-based ink using the organic pigment mass can be stored for a long period of time.
However, there is a need for an aqueous dispersion for inkjet recording and a water-based ink having a higher level of superior performance.

International Publication No. 00/39226 Pamphlet JP-A-11-49974

  The present invention is a stable aqueous dispersion of water-insoluble vinyl polymer particles containing a quinacridone pigment, which has a high gloss when printed on special paper while satisfying a high print density when printed on plain paper. It is an object of the present invention to provide a water-based ink for ink-jet recording capable of achieving a high level of fixability and fixability, and an aqueous dispersion for ink-jet recording used in the production of the ink.

The present inventors include, as a colorant, a quinacridone pigment (A) and a pigment derivative (B) obtained by introducing an acidic group into an organic pigment (hereinafter simply referred to as “pigment derivative (B)”). It has been found that the above-mentioned problems can be solved by using a water-insoluble vinyl polymer.
That is, the present invention is an aqueous dispersion of water-insoluble vinyl polymer particles containing a quinacridone pigment (A) and a pigment derivative (B), and the water-insoluble vinyl polymer is represented by the following formula (1). Provided are an aqueous dispersion for inkjet recording having a structural unit, and an aqueous ink containing the same.

（式中、Ｒ¹は水素原子又はメチル基を示し、Ｒ²は、置換基を有していてもよい、炭素数７〜２２のアリールアルキル基又は炭素数６〜２２のアリール基を示す。）

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an arylalkyl group having 7 to 22 carbon atoms or an aryl group having 6 to 22 carbon atoms, which may have a substituent. )

  The aqueous dispersion for ink-jet recording of the present invention is an aqueous dispersion excellent in stability of water-insoluble vinyl polymer particles containing a quinacridone pigment. The water-based ink containing this aqueous dispersion is excellent in dispersion stability and ejection properties, and satisfies the high print density when printed on plain paper, while having excellent gloss and fixability when printed on special paper. It can be expressed.

  The aqueous dispersion for inkjet recording of the present invention is an aqueous dispersion of water-insoluble vinyl polymer particles containing a quinacridone pigment (A) and a pigment derivative (B), and the water-insoluble vinyl polymer is represented by the formula (1). It has the structural unit represented by these. Hereinafter, each of these components will be described sequentially.

(Quinacridone pigment (A))
Examples of the quinacridone pigment used in the present invention include C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 209, C.I. I. Pigment violet 19 and the like. These can be used alone or in admixture of two or more.
Among these, from the viewpoint of color tone, C.I. I. Pigment red 122 and / or C.I. I. Pigment Violet 19 is preferred.

(Pigment derivative (B))
The pigment derivative (B) has a function as a surface treating agent for the quinacridone pigment (A) and is used to improve the dispersion stability of the quinacridone pigment (A).
As the pigment derivative (B), those obtained by introducing an acidic group into the organic pigment as a hydrophilic dispersibility-imparting group are used from the viewpoint of making the quinacridone pigment (A) finer and dispersion stability. As the acidic group, —COOM, —SO ₃ M, —SO ₂ M, —PO ₃ HM, —PO ₃ M (wherein M represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium). 1 type or 2 or more types of functional groups chosen from the group which consists of the functional group represented by these, or its salt are mentioned. Among these acidic groups, a sulfonic acid group (—SO ₃ M) is preferable from the viewpoint of dispersion stability.

Examples of the organic pigment into which an acidic group is introduced include quinacridone pigments, phthalocyanine pigments, azo pigments, quinophthalone pigments, and isoindolinone pigments. The hue is not particularly limited, and red organic pigments, yellow organic pigments, blue organic pigments, orange organic pigments, green orange organic pigments, and the like can be used.
Examples of the red organic pigment include C.I. which is a quinacridone pigment. I. Pigment red 122, 202, 209, etc., or C.I. I. Pigment Violet 19 and the like are preferable. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 17, 22, 23, 30, 31, 38, 88, 112, 114, 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 219 and the like.
Examples of the yellow organic pigment include C.I. I. Pigment Yellow 1, 2, 3, 5, 6, 10, 12, 13, 14, 15, 16, 17, 24, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 117, 120, 138, 153, etc. In addition, C.I. I. Pigment yellow 109, 110, and the like.
Examples of the blue organic pigment include C.I. which is a phthalocyanine pigment. I. Pigment blue 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, and the like, and C.I. I. Pigment blue 56,606 and the like.
Examples of orange organic pigments include C.I. I. Pigment Orange 5, 13, 16, 36, 43, 51, etc. Examples of green organic pigments include C.I. I. Pigment green 7, 10, 36, and the like.
Among these, from the viewpoints of improving the adsorptivity to the surface of the quinacridone pigment (A), making the quinacridone pigment (A) fine particles, mixing / dispersing stability with a water-insoluble vinyl polymer, and hue, quinacridone pigments ( The pigment derivative (B) having the same quinacridone skeleton as in A) is preferred. I. Pigment red 122, C.I. I. Pigment violet 19 pigment derivative (B) is preferred.

Examples of the sulfonated quinacridone pigment derivative obtained by introducing a sulfonic acid group into a quinacridone pigment include sulfonated quinacridone, sulfonated-2,9-dimethylquinacridone and the like, and sodium, aluminum, and calcium thereof. And ammonium salts such as ammonium, octadecylammonium, didodecylammonium, dimethyloctadecylammonium, dimethyldioctadecylammonium, benzyldimethyloctadecylammonium, and the like.
Among these, sulfonated quinacridone or sulfonated dimethylquinacridone is most preferable from the viewpoint of fine particle formation and dispersion stability of the quinacridone pigment (A).
The sulfonated quinacridone pigment derivative can be synthesized by reacting a quinacridone pigment with a sulfonating agent such as concentrated sulfuric acid, fuming sulfuric acid or chlorosulfuric acid by a known method.

(Coloring agent)
The quinacridone pigment (A) and the pigment derivative (B) can be used alone or in admixture of two or more.
The mixing ratio of the quinacridone pigment (A) and the pigment derivative (B) is such that the pigment derivative (B) is 0.5 to 100 parts by weight with respect to 100 parts by weight of the quinacridone pigment (A) from the viewpoints of dispersion stability and color tone. 20 parts by weight is preferable, and 1 to 10 parts by weight is more preferable. In this range, the amount of the pigment derivative adsorbed on the surface of the quinacridone pigment is preferable, and the storage stability is excellent.
When mixing the quinacridone pigment (A) and the pigment derivative (B), they may be synthesized and mixed in the same synthesis tank, or the quinacridone pigment (A) and the pigment derivative (B) are synthesized separately, You may mix in any processes, such as a subsequent drying process, a grinding | pulverization process, a classification process, and a pigment dispersion process.

The content of the quinacridone pigment (A) and the pigment derivative (B) (collectively referred to as “colorant”) in the aqueous dispersion and aqueous ink of the present invention is from the viewpoint of increasing dispersion stability and print density. 1 to 30 weight% is preferable, 2 to 20 weight% is more preferable, and 2 to 10 weight% is still more preferable.
The amount ratio of the water-insoluble vinyl polymer and the colorant used in the present invention is preferably 20 to 1,000 parts by weight of the colorant with respect to 100 parts by weight of the solid content of the water-insoluble vinyl polymer from the viewpoint of increasing the printing density. 50 to 900 parts by weight is more preferable, and 100 to 800 parts by weight is still more preferable.

(Water-insoluble vinyl polymer)
The water-insoluble vinyl polymer used in the present invention has a structural unit represented by the following formula (1). When water-insoluble vinyl polymer particles having a structural unit represented by the following formula (1) are mixed with water-based ink containing quinacridone pigment (A) and pigment derivative (B), and printed on dedicated paper In particular, excellent gloss and fixing properties can be exhibited.

式（１）中、Ｒ¹は水素原子又はメチル基を示す。Ｒ²は、置換基を有していてもよい、炭素数７〜２２、好ましくは炭素数７〜１８、更に好ましくは炭素数７〜１２のアリールアルキル基、又は、炭素数６〜２２、好ましくは炭素数６〜１８、更に好ましくは炭素数６〜１２のアリール基を示す。置換基には、ヘテロ原子を含んでいてもよい。ヘテロ原子としては、窒素原子、酸素原子及び硫黄原子が挙げられる。
Ｒ²の具体例としては、ベンジル基、フェネチル基（フェニルエチル基）、フェノキシエチル基、ジフェニルメチル基、トリチル基等が挙げられる。
置換基の具体例は、好ましくは炭素数１〜９の、アルキル基、アルコキシ基若しくはアシロキシ基、水酸基、エーテル基、エステル基又はニトロ基等が挙げられる。
式（１）で表される構成単位としては、高光沢性を発現させる観点から、特にベンジル（メタ）アクリレートに由来する構成単位が好ましい。

In the formula (1), R ¹ represents a hydrogen atom or a methyl group. R ² may have a substituent, which has 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably an arylalkyl group having 7 to 12 carbon atoms, or 6 to 22 carbon atoms, preferably Represents an aryl group having 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms. The substituent may contain a hetero atom. Examples of the hetero atom include a nitrogen atom, an oxygen atom, and a sulfur atom.
Specific examples of R ² include benzyl group, phenethyl group (phenylethyl group), phenoxyethyl group, diphenylmethyl group, and trityl group.
Specific examples of the substituent include preferably an alkyl group, an alkoxy group or an acyloxy group, a hydroxyl group, an ether group, an ester group or a nitro group having 1 to 9 carbon atoms.
As the structural unit represented by the formula (1), a structural unit derived from benzyl (meth) acrylate is particularly preferable from the viewpoint of developing high gloss.

The structural unit represented by the formula (1) is preferably obtained by polymerizing a monomer represented by the following formula (1-1).
CH ₂ = CR ¹ COOR ² (1-1)
(Wherein R ¹ and R ² are the same as described above.)
Specifically, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 1-naphthyl acrylate, 2-naphthyl (meth) acrylate, phthalimidomethyl (meta ) Acrylate, p-nitrophenyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate, etc. Thereby, the polymer which has a structural unit represented by Formula (1) is compoundable. Among these, benzyl (meth) acrylate is particularly preferable. These can be used alone or in admixture of two or more.
As used herein, “(meth) acryl” means “acryl”, “methacryl”, or a mixture thereof.

  The water-insoluble vinyl polymer used in the present invention preferably further has a structural unit represented by the following formula (2).

式（２）中、Ｒ³は水素原子又はメチル基を示し、Ｒ⁴Ｏはオキシプロピレン基を示す。Ｒ⁴Ｏには、−ＣＨ₂ＣＨ（ＣＨ₃）Ｏ−以外に、−ＣＨ（ＣＨ₃）ＣＨ₂Ｏ−が含まれていてもよい。Ｒ⁵Ｏは炭素数２又は４のオキシアルキレン基を示し、オキシエチレン基、オキシテトラメチレン基を示す。
Ｒ⁶は、水素原子、炭素数１〜２０のアルキル基、又は炭素数１〜９のアルキル基を有してもよいフェニル基を示す。Ｒ⁶は、高い印字濃度及び良好な保存安定性の観点から、炭素数１〜１２のアルキル基が好ましく、炭素数１〜８のアルキル基がより好ましい。また、炭素数１〜８のアルキル基を有していてもよい、フェニル基が好ましい。炭素数１〜８のアルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、ｔ−ブチル基、ヘキシル基、オクチル基、２-エチルヘキシル基等が挙げられる。
Ｒ⁴Ｏ及びＲ⁵Ｏはランダム付加又はブロック付加している。Ｒ⁴Ｏ及びＲ⁵Ｏが、ブロック付加している場合、-ＣＯＯ-（Ｒ⁴Ｏ）x-（Ｒ⁵Ｏ）y-Ｒ⁶、又は-ＣＯＯ-（Ｒ⁵Ｏ）y -（Ｒ⁴Ｏ）x -Ｒ⁶の何れであってもよい。ｘ、ｙは、平均付加モル数を表し、ｘは１〜３０の数であり、２〜３０が好ましく、３〜２０が更に好ましく、３〜１５が特に好ましい。ｙは０〜３０の数であり、０〜２０が好ましく、０〜１５が更に好ましい。ｙ個のＲ⁵Ｏは同一でも異なっていてもよい。

In formula (2), R ³ represents a hydrogen atom or a methyl group, and R ⁴ O represents an oxypropylene group. R ⁴ O may contain —CH (CH ₃ ) CH ₂ O— in addition to —CH ₂ CH (CH ₃ ) O—. R ⁵ O represents an oxyalkylene group having 2 or 4 carbon atoms, and represents an oxyethylene group or an oxytetramethylene group.
R ⁶ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group that may have an alkyl group having 1 to 9 carbon atoms. R ⁶ is preferably an alkyl group having 1 to 12 carbon atoms and more preferably an alkyl group having 1 to 8 carbon atoms from the viewpoint of high printing density and good storage stability. Moreover, the phenyl group which may have a C1-C8 alkyl group is preferable. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, hexyl group, octyl group, and 2-ethylhexyl group.
R ⁴ O and R ⁵ O are randomly added or block added. When R ⁴ O and R ⁵ O are added as a block, —COO— (R ⁴ O) x — (R ⁵ O) y —R ⁶ or —COO— (R ⁵ O) y — (R ⁴ O) Any of x -R ⁶ may be used. x and y represent an average added mole number, x is a number of 1 to 30, 2 to 30 is preferable, 3 to 20 is more preferable, and 3 to 15 is particularly preferable. y is a number from 0 to 30, preferably 0 to 20, and more preferably 0 to 15. The y R ⁵ Os may be the same or different.

The structural unit represented by the formula (2) is preferably obtained by polymerizing a monomer represented by the following formula (2-1).
^{_{CH 2 = CR 3 COO- (R}} 4 O) x - (R 5 O) y -R 6 (2-1)
(In the formula, R ³ , R ⁴ O, R ⁵ O, R ⁶ , x, and y are the same as described above.)
Among the formulas (2), the structural unit represented by the following formula (3) or (4) is preferable for giving high print density, and the water-insoluble vinyl polymer used in the present invention is represented by the following formula (3): You may have both the structural units represented by following formula (4).

（式中、Ｒ³、ｘ、Ｒ⁶は、前記と同じである。）
式（３）は、式（２）において、ｙが０の場合である。

(In the formula, R ³ , x and R ⁶ are the same as described above.)
Formula (3) is a case where y is 0 in Formula (2).

The structural unit represented by the formula (3) is preferably obtained by polymerizing a monomer represented by the following formula (3-1).
^{_{CH 2 = CR 3 COO- (CH}} 2 CH (CH 3) O) x -R 6 (3-1)
(In the formula, R ³ , R ⁶ and x are the same as described above.)
Specifically, polypropylene glycol mono (meth) acrylate, methoxypolypropylene glycol mono (meth) acrylate, ethoxypolypropylene glycol mono (meth) acrylate, octoxypolypropylene glycol mono (meth) acrylate, stearoxy polypropylene glycol mono (meth) acrylate , Nonylphenoxy polypropylene glycol mono (meth) acrylate, phenoxy polypropylene glycol mono (meth) acrylate, and the like. Among these, polypropylene glycol mono (meth) acrylate is particularly preferable. These can be used alone or in admixture of two or more.

  On the other hand, Formula (4) is a case where y is 1 or more in Formula (2) above.

（式（４）中、Ｒ³、Ｒ⁶、ｘは、前記と同じである。（ＣＨ₂ＣＨ（ＣＨ₃）Ｏ）と（（ＣＨ₂）_PＯ）は、ランダム付加又はブロック付加しており、ブロック付加の場合、-ＣＯＯ-（ＣＨ₂ＣＨ（ＣＨ₃）Ｏ）_X-（（ＣＨ₂）_PＯ）_Z-Ｒ⁶ 又は、-ＣＯＯ-（（ＣＨ₂）_PＯ）_Z-（ＣＨ₂ＣＨ（ＣＨ₃）Ｏ）_X-Ｒ⁶の何れであってもよい。ｐは２又は４の数であり、ｚは、平均付加モル数を表し、１〜３０の数であり、２〜２０が好ましく、３〜１５が更に好ましい。）

(In the formula (4), R ³ , R ⁶ and x are the same as described above. (CH ₂ CH (CH ₃ ) O) and ((CH ₂ ) _P O) are added randomly or in blocks. cage, in the case of block _{addition, -COO- (CH 2 CH (CH} 3) O) X - ((CH 2) P O) Z -R 6 _{or, -COO - ((CH 2)} P O) Z - ( CH ₂ CH (CH ₃ ) O) _X —R ⁶ may be used, p is a number of 2 or 4, z is an average number of added moles, is a number of 1 to 30, 2 -20 are preferable, and 3-15 are more preferable.)

The structural unit represented by the formula (4) is preferably obtained by polymerizing a monomer represented by the following formula (4-1) or (4-2).
^{_{CH 2 = CR 3 COO- (CH}} 2 CH (CH 3) O) x - (CH 2 CH 2 O) z -R 6 (4-1)
^{_{CH 2 = CR 3 COO- (CH}} 2 CH (CH 3) O) x - ((CH 2) 4 O) z -R 6 (4-2)
(Wherein R ³ , R ⁶ , x and z are the same as described above. (CH ₂ CH (CH ₃ ) O), (CH ₂ CH ₂ O), and (CH ₂ CH (CH ₃ ) O). ) And ((CH ₂ ) ₄ O) are randomly or block-added. In the case of block addition, CH ₂ = CR ³ COO- (CH ₂ CH (CH ₃ ) O) _x- (CH ₂ CH ₂ O) _z -R ⁶ or ^{_{CH 2 = CR 3 COO- (CH}} 2 CH 2 O) z - (CH 2 CH (CH 3) O) may be either _{^{x -R 6, CH 2 = CR}} 3 _{COO- (CH 2 CH (CH 3} ) O) x - ((CH 2) 4 O) z -R 6 or ^{_{CH 2 = CR 3 COO - (}} (CH 2) 4 O) z - (CH 2 CH (CH ₃₎ O) may be either _x -R ^6.)

  Specifically, ethylene glycol / propylene glycol (meth) acrylate, poly (ethylene glycol / propylene glycol) mono (meth) acrylate [ethylene glycol and propylene glycol are randomly bonded], octoxypolyethylene glycol / polypropylene glycol mono (Meth) acrylate [polyethylene glycol and polypropylene glycol are block-bonded. Including block bonding of polyethylene glycol and polypropylene glycol from the (meth) acryl group side and vice versa. same as below. ], Octoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, stearoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, stearoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, phenoxy polyethylene glycol / polypropylene Glycol mono (meth) acrylate, phenoxypoly (ethylene glycol / propylene glycol) mono (meth) acrylate, nonylphenoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, nonylphenoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate Poly (propylene glycol / tetramethylene glycol monomer) Among them, poly (ethylene glycol / propylene glycol) mono (meth) acrylate and poly (propylene glycol / tetramethylene glycol monomethacrylate) are particularly preferable, and these may be used alone or in combination of two or more. It can be used by mixing.

  Weight ratio of the structural units represented by the formula (1) and the formula (2) in the water-insoluble vinyl polymer used in the present invention [the structural unit represented by the formula (1) / the formula (2) The structural unit] is preferably from 1/2 to 10/1, more preferably from 1/2 to 8/1, and more preferably from 1/2 to 5/1 from the viewpoint of achieving both print density and glossiness and imparting fixability. More preferably, 1/1 to 5/1 is most preferable.

The water-insoluble vinyl polymer preferably further contains a structural unit derived from the salt-forming group-containing monomer (a) from the viewpoint of improving the dispersibility. The structural unit derived from the salt-forming group-containing monomer (a) can be obtained by polymerizing the salt-forming group-containing monomer, but after polymerization of the polymer, the salt-forming group (anionic group or cationic group) is added to the polymer chain. ) May be introduced.
As the salt-forming group-containing monomer (a), (a-1) an anionic monomer and (a-2) a cationic monomer are preferable.

(A-1) As an anionic monomer, 1 or more types chosen from the group which consists of an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer are mentioned.
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) -itaconate, 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-acrylic acid. And leuoxyethyl phosphate.
Among the above anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of ink viscosity and dischargeability.

(A-2) As a cationic monomer, 1 or more types chosen from the group which consists of an unsaturated tertiary amine containing vinyl monomer and an unsaturated ammonium salt containing vinyl monomer are mentioned.
Examples of the unsaturated tertiary amine-containing monomer include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N, N. -Dimethylaminopropyl (meth) acrylamide, vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-6-vinylpyridine, 5-ethyl-2-vinylpyridine and the like.
Examples of unsaturated ammonium salt-containing monomers include N, N-dimethylaminoethyl (meth) acrylate quaternized product, N, N-diethylaminoethyl (meth) acrylate quaternized product, N, N-dimethylaminopropyl (meth). Examples include acrylate quaternized products.
Among the above cationic monomers, N, N-dimethylaminoethyl (meth) acrylate, NN-dimethylaminopropyl (meth) acrylamide and vinylpyrrolidone are preferable.
Said (a) salt production | generation group containing monomer can be used individually or in mixture of 2 or more types.

The water-insoluble vinyl polymer preferably further contains a structural unit derived from the styrenic macromer (b) and / or the hydrophobic monomer (c) from the viewpoint of improving dispersion stability, printing density and marker resistance.
Examples of the styrenic macromer (b) include a styrene homopolymer having a polymerizable functional group at one end, and a copolymer of styrene and another monomer having a polymerizable functional group at one end. The polymerizable functional group present at one end is preferably an acryloyloxy group or a methacryloyloxy group, and by copolymerizing these, a water-insoluble vinyl polymer having a structural unit derived from a styrenic macromer can be obtained.

Examples of the other monomer include (1) (meth) acrylonitrile, (2) an alkyl group having 1 to 22 carbon atoms, preferably 1 to 18 carbon atoms which may have a hydroxy group, ) Acrylates, (3) aromatic ring-containing monomers other than styrene, and the like.
(2) Specific examples of (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (iso or tarsha Lee) butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) stearyl (meth) acrylate, and the like.
In the present specification, “(iso or tertiary)” and “(iso)” are the case where the branched structure represented by “iso” or “tertiary” is present or not present (normal). Both are shown.
(3) As aromatic ring-containing monomers other than styrene, for example, α-methylstyrene, vinyl toluene, vinyl naphthalene, ethyl vinyl benzene, 4-vinyl biphenyl, 1,1-diphenyl ethylene, benzyl (meth) acrylate, Examples thereof include vinyl monomers having 6 to 22 carbon atoms such as phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate.
These can be used alone or in admixture of two or more.

The content of the structural unit derived from styrene in the styrenic macromer (b) is preferably 60% by weight or more, more preferably from the viewpoint of sufficiently containing the colorant in the water-insoluble vinyl polymer particles and improving the printing density. It is 70% by weight or more, particularly preferably 90% by weight or more.
The number average molecular weight of the styrenic macromer (b) is preferably from 1,000 to 10,000, and more preferably from 2,000 to 8,000, from the viewpoint of keeping the viscosity low while increasing the copolymerization ratio in order to enhance the storage qualities.
The number average molecular weight of the styrenic macromer is a value measured by gel permeation chromatography using polystyrene as a standard substance and tetrahydrofuran containing 50 mmol / L acetic acid as a solvent.
Examples of commercially available styrenic macromers include trade names of Toa Gosei Co., Ltd., AS-6, AS-6S, AN-6, AN-6S, HS-6, HS-6S, and the like.

The structural unit derived from the hydrophobic monomer (c) can be obtained by polymerizing the hydrophobic monomer. However, after the polymerization of the polymer, the hydrophobic monomer may be introduced into the polymer chain.
As the hydrophobic monomer (c), (c-1) (meth) acrylate having an alkyl group having 1 to 22 carbon atoms or (c-2) a monomer represented by the following formula (5) is preferable.
^{_{CH 2 = C (R 7)}} -R 8 (5)
(In the formula, R ⁷ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ⁸ represents an aromatic ring-containing hydrocarbon group having 6 to 22 carbon atoms.)
(C-1) As a (meth) acrylate having an alkyl group having 1 to 22 carbon atoms, methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (Meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (iso) stearyl (meth) acrylate, Examples include heenyl (meth) acrylate.
(C-2) As the monomer represented by the formula (5), from the viewpoint of printing density, styrene, vinyl naphthalene, α-methylstyrene, vinyl toluene, ethyl vinyl benzene, 4-vinyl biphenyl, 1,1-diphenyl One or more selected from ethylene is preferred. Among these, from the viewpoint of printing density and storage stability, a styrene monomer that is one or more selected from the group consisting of styrene, α-methylstyrene, and vinyltoluene is more preferable.

The water-insoluble vinyl polymer may further contain other structural units. As other structural units, for example, a silicone macromer having a polymerizable functional group at one end, preferably an alkyl methacrylate macromer (methyl methacrylate) having a polymerizable functional group at one end, represented by the following formula (6): Structural macromer, butyl acrylate macromer, isobutyl methacrylate macromer, etc.).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _t - Si (CH ₃ ) ₃ (6)
(Wherein t represents a number of 8 to 40)

  The water-insoluble vinyl polymer contains a monomer represented by the formula (1-1) and a monomer represented by the formula (2-1), and if necessary, (a) a salt-forming group-containing monomer, ( What is obtained by copolymerizing a monomer mixture (hereinafter referred to as “monomer mixture”) containing b) a styrenic macromer and / or (c) a hydrophobic monomer or the like is preferable.

The monomer content represented by the formula (1-1) in the monomer mixture or the content of the structural unit represented by the formula (1) in the water-insoluble vinyl polymer is determined by the print density and gloss when the water-based ink is used. From the viewpoints of improvement in properties, fixing properties and good dispersion stability, it is 10% by weight or more, preferably 10 to 80% by weight, more preferably 20 to 80% by weight, and particularly preferably 25 to 75% by weight.
The monomer content represented by the formula (2-1) in the monomer mixture or the content of the structural unit represented by the formula (2) in the water-insoluble vinyl polymer is determined by the print density and gloss when the water-based ink is used. From the viewpoint of improvement in properties, fixability and good dispersion stability, it is preferably 5 to 60% by weight, more preferably 8 to 55% by weight, and particularly preferably 10 to 50% by weight.

Content of the salt-forming group-containing monomer (a) in the monomer mixture (content as an unneutralized amount; the same applies hereinafter), or the content of structural units derived from the salt-forming group-containing monomer (a) in the water-insoluble vinyl polymer Is preferably from 3 to 30% by weight, more preferably from 5 to 25% by weight, particularly preferably from 5 to 20% by weight, from the viewpoints of improving the printing density and glossiness when using water-based ink and good dispersion stability. It is.
The weight ratio of [the structural unit represented by the formula (1) / the structural unit derived from the salt-forming group-containing monomer (a)] is preferably 10 / from the viewpoint of improving the dispersibility and gloss of the water-insoluble vinyl polymer. 1-1 / 1, more preferably 8/1 to 2/1.
The weight ratio of [the structural unit represented by the formula (2) / the structural unit derived from the salt-forming group-containing monomer (a)] is preferably 10 / from the viewpoint of improving the dispersibility of the water-insoluble vinyl polymer and the print density. 1 to 1/1, more preferably 5/1 to 1/1.
The content of the styrenic macromer (b) in the monomer mixture or the content of the structural unit derived from the styrenic macromer (b) in the water-insoluble vinyl polymer is preferably 0 from the viewpoint of printing density when the aqueous ink is used. -40% by weight, more preferably 5-35% by weight, particularly preferably 5-30% by weight.
The content of the hydrophobic monomer (c) in the monomer mixture or the content of the structural unit derived from the hydrophobic monomer (c) in the water-insoluble vinyl polymer is from the viewpoint of the print density and dispersion stability when the water-based ink is used. The amount is preferably 0 to 40% by weight, more preferably 0 to 20% by weight.

The water insolubility of the insoluble vinyl polymer is preferably 10 g or less, more preferably 5 g or less, and particularly preferably 1 g or less, from the viewpoint of reducing the viscosity of the water-based ink. When it has a salt-forming group, it is the dissolved amount of the water-insoluble vinyl polymer after 100% neutralization with sodium hydroxide or acetic acid depending on the type of the salt-forming group.
The water-insoluble vinyl polymer is used by neutralizing a salt-forming group derived from a salt-forming group-containing monomer with a neutralizing agent described later. 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) × weight of polymer (g) / (36.5 × 1000)]] × 100
The acid value and amine value can be calculated from the constituent unit of the water-insoluble vinyl 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 weight average molecular weight of the water-insoluble vinyl polymer is preferably from 5,000 to 500,000, more preferably from 10,000 to 400,000, from the viewpoints of dispersion stability of the colorant, water resistance and dischargeability. ~ 300,000 is particularly preferred.
The weight average molecular weight of the water-insoluble vinyl polymer is measured by gel chromatography using 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide-containing dimethylformamide as a solvent using polystyrene as a standard substance.

(Method for producing water-insoluble vinyl polymer)
The water-insoluble vinyl 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 and methyl ethyl ketone; esters such as ethyl acetate and the like. Among these, methanol, ethanol, acetone, methyl ethyl ketone, or a mixed solvent of one or more of these and water is preferable.

In the polymerization, a radical polymerization initiator can be used. As radical polymerization initiators, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobisbutyrate, 2,2 An azo compound such as' -azobis (2-methylbutyronitrile) and 1,1'-azobis (1-cyclohexanecarbonitrile) is preferred. Moreover, organic peroxides, such as t-butyl peroxy octoate, di-t-butyl peroxide, dibenzoyl oxide, can also 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 polymerization chain transfer agent may be further added. Specific examples of the polymerization chain transfer agent include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-tetradecyl mercaptan, mercaptoethanol, 3-mercapto-1,2-propanediol and mercaptosuccinic acid. Thiuram disulfides; hydrocarbons; unsaturated cyclic hydrocarbon compounds; unsaturated heterocyclic compounds, and the like. These may be used alone or in admixture of two or more.

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 water-insoluble vinyl polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained water-insoluble polymer can be purified by repeating reprecipitation or removing unreacted monomers by membrane separation, chromatographic method, extraction method or the like.

(Method for producing water dispersion and water-based ink)
The aqueous dispersion of the present invention is preferably obtained by the following steps (1) and (2).
Step (1): A step of dispersing a mixture containing a water-insoluble vinyl polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent Step (2): a step of removing the organic solvent The step (1) First, the water-insoluble vinyl polymer is dissolved in an organic solvent, and then a colorant, water, and if necessary, a neutralizing agent, a surfactant and the like are added to the organic solvent and mixed to obtain an oil-in-water type. To obtain a dispersion. In the mixture, the colorant is preferably 5 to 50% by weight, the organic solvent is preferably 10 to 70% by weight, the water-insoluble polymer is preferably 2 to 40% by weight, and the water is preferably 10 to 70% by weight. . When the water-insoluble vinyl 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 vinyl polymer.

Preferred examples of the organic solvent include alcohol solvents, ketone solvents, and ether solvents, and those having a solubility in water of 50% by weight or less and 10% by weight or more at 20 ° C. are preferable.
Examples of alcohol solvents include ethanol, isopropanol, n-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Among these solvents, isopropanol, acetone and methyl ethyl ketone are preferable, and methyl ethyl ketone is particularly preferable. These solvents can be used alone or in admixture of two or more.
As the neutralizing agent, an acid or a base can be used depending on the kind of the salt-forming group in the water-insoluble vinyl polymer.
Examples of neutralizers include 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, methyl Examples include bases such as amine, dimethylamine, trimethylamine, ethylamine, diethylamine, trimethylamine, and triethanolamine.

There is no restriction | limiting in particular in the dispersion method of the mixture in the said process (1). The average particle size of the water-insoluble polymer particles can be atomized only by the main dispersion until the desired particle size is reached. Preferably, after pre-dispersing, the main dispersion is further performed by applying shear stress to the water-insoluble polymer particles. It is preferable to control the average particle size of the particles to a desired particle size.
When the mixture is predispersed, a commonly used mixing and stirring device such as an anchor blade can be used. Among the mixing and stirring devices, Ultra Disper [Asada Steel Co., Ltd., trade name], Ebara Milder [Ebara Seisakusho Co., Ltd., trade name], TK Homomixer, TK Pipeline Mixer, TK Homojetter, TK Homomic Line Flow, High-speed agitating and mixing devices such as Filmix [Special Machine Industry Co., Ltd., trade name], Clear Mix [M Technique Co., Ltd., trade name], KD Mill [Kinetic Dispersion Co., Ltd., trade name] and the like are preferable.
As means for applying 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) Representative homo-valve type high-pressure homogenizer, microfluidizer (Microfluidics, trade name), nanomizer (Nanomizer, trade name), optimizer (Sugino machine, trade name), Genus PY (Shiramizu Chemical Co., Ltd.) Product name], DeBEE2000 [Japan EE Co., Ltd., product name] and the like chamber type high-pressure homogenizer. In these, a roll mill, a kneader, and a microfluidizer are preferable.

In the step (2), an aqueous dispersion of water-insoluble polymer particles containing a colorant is obtained by distilling the organic solvent from the dispersion obtained in the step (1) into an aqueous system. The organic solvent contained in the aqueous dispersion can be removed by a general method such as distillation under reduced pressure. The organic solvent in the aqueous dispersion containing the obtained water-insoluble polymer particles is substantially removed, and the amount of the organic solvent is usually 0.1% by weight or less, preferably 0.01% by weight or less.
The aqueous dispersion of water-insoluble polymer particles containing a colorant is a dispersion in which a solid content of a water-insoluble polymer containing a colorant is dispersed in water as a main solvent. Here, the form of the water-insoluble polymer particles containing the colorant is not particularly limited as long as the particles are formed of at least the colorant and the water-insoluble polymer. For example, a particle form in which a colorant is included in a water-insoluble polymer, a particle form in which a colorant is uniformly dispersed in a water-insoluble polymer, a particle form in which a colorant is exposed on the surface of a water-insoluble polymer particle, and the like are included.

The water dispersion of water-insoluble vinyl polymer particles may be used as it is as a water-based ink containing water as a main solvent, but a wetting agent, penetrating agent, dispersant, viscosity modifier, water-dissipating agent usually used in water-based inks for inkjet recording. You may add a foaming agent, an antifungal agent, an antirust agent, etc.
The average particle size of the water-insoluble vinyl polymer particles containing the colorant in the obtained water dispersion and water-based ink is preferably 0.01 to 0.5 μm from the viewpoint of preventing clogging of the printer nozzle and dispersion stability. More preferably, it is 0.03-0.3 micrometer, Most 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.

In addition, the content (solid content) of the water-insoluble vinyl polymer particles containing the colorant in the aqueous dispersion and the water-based ink is preferably 0.5 to 30% by weight from the viewpoint of printing density and ejection stability. More preferably, the content is adjusted to 1 to 25% by weight, and more preferably 2 to 15% by weight.
The water content in the aqueous dispersion and the water-based ink of the present invention is preferably 30 to 90% by weight, more preferably 40 to 80% by weight.
The preferred surface tension (20 ° C.) of the aqueous dispersion and aqueous ink of the present invention is 30 to 65 mN / m, more preferably 35 to 60 mN / m as the aqueous dispersion, and 25 to 50 mN / m as the aqueous ink. m, more preferably 27 to 45 mN / m.
The viscosity (20 ° C.) of 10% by weight of the aqueous dispersion of the present invention is preferably 2 to 6 mPa · s, and more preferably 2 to 5 mPa · s in order to obtain a preferable viscosity when an aqueous ink is used. In addition, the viscosity (20 ° C.) of the water-based ink of the present invention is preferably 2 to 12 mPa · s, and more preferably 2.5 to 10 mPa · s in order to maintain good ejection properties.

In the following production examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified.
(Production of water-insoluble vinyl polymer)
Production Examples 1-2 and Comparative Production Example 1
In a reaction vessel, 20 parts of methyl ethyl ketone, 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol), and 10% of 800 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, in a dropping funnel, 90% of 800 parts of the monomer shown in Table 1 was charged and 0.27 part of the polymerization chain transfer agent, 60 parts of methyl ethyl ketone and 2,2′-azobis (2,4-dimethylvaleronitrile) 1 2 parts were 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 prepared by dissolving 0.3 part of 2,2′-azobis (2,4-dimethylvaleronitrile) in 5 parts of methyl ethyl ketone was added, and further at 65 ° C. for 2 hours, 70 ° C. For 2 hours to obtain a polymer solution.
A portion of the resulting polymer solution was isolated by drying at 105 ° C. under reduced pressure for 2 hours and removing the solvent. The weight average molecular weight was measured by the above measuring method. The results are shown in Table 1.

The details of the compounds shown in Table 1 are as follows.
Polypropylene glycol monomethacrylate: average number of added moles of polypropylene oxide = average 9 mol, terminal hydroxyl group (manufactured by NOF Corporation, trade name: BLEMMER PP500)
Polyethylene glycol monomethacrylate: average addition mole number of polyethylene oxide = average 9 mol, terminal methyl group (made by Shin-Nakamura Chemical Co., Ltd., trade name: NK ester M-90G)
Styrene macromer: manufactured by Toa Gosei Co., Ltd., trade name: AS-6S, number average molecular weight 6000, polymerizable functional group: methacryloyloxy group

(Manufacture of colorants)
Production Example 3
Under a low temperature condition of 5 to 10 ° C., 2,9-dimethylquinacridone pigment (CI Pigment Red 122, manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the fuming sulfuric acid and reacted, Poured into ice water. The resulting suspension was filtered and further washed, and the resulting product was dried to obtain sulfonated-2,9-dimethylquinacridone.
2,9-dimethylquinacridone in which 2.5 parts of sulfonated-2,9-dimethylquinacridone is mixed with 100 parts of the 2,9-dimethylquinacridone pigment and sulfonated-2,9-dimethylquinacridone is mixed. A pigment was obtained.

Production Example 4
Under a low temperature condition of 5 to 10 ° C., an unsubstituted quinacridone pigment (CI Pigment Violet 19, manufactured by Clariant Japan Co., Ltd.) was added to fuming sulfuric acid, and the mixture was reacted and then poured into ice water. The resulting suspension was filtered and further washed, and the resulting product was dried to obtain sulfonated quinacridone.
100 parts of the unsubstituted quinacridone pigment was mixed with 5 parts of a sulfonated quinacridone to obtain an unsubstituted quinacridone pigment mixed with a sulfonated quinacridone.

(Manufacture of water dispersion)
Example 1
6 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure was dissolved in 45 parts of methyl ethyl ketone, and a predetermined amount of a neutralizing agent (20% aqueous sodium hydroxide solution) was contained therein (degree of neutralization 70%). In addition, the salt-forming groups were neutralized, and 18 parts of 2,9-dimethylquinacridone pigment mixed with the sulfonated-2,9-dimethylquinacridone obtained in Production Example 3 was added, and it was not dried on a three-roll mill. An appropriate amount of ion-exchanged water was added to and kneaded for 30 minutes.
To the obtained kneaded product, 100 parts of ion-exchanged water was added and stirred, and then methyl ethyl ketone was removed at 60 ° C. under reduced pressure to further remove part of the water, and the resulting dispersion was filtered with a 5.0 μm filter. (Acetyl cellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) A pigment-containing vinyl polymer particle having a solid content of 20%, filtered through a 25 mL needleless syringe (manufactured by Terumo Corp.). An aqueous dispersion was obtained.

Example 2
An aqueous dispersion of pigment-containing vinyl polymer particles in Example 1, except that the polymer solution obtained in Production Example 2 was used instead of the polymer solution obtained in Production Example 1. Got.

Example 3
In Example 1, in place of the 2,9-dimethylquinacridone pigment mixed with the sulfonated-2,9-dimethylquinacridone obtained in Preparation Example 3, the sulfonated quinacridone obtained in Preparation Example 4 was mixed. An aqueous dispersion of pigment-containing vinyl polymer particles was obtained in the same manner as in Example 1 except that the quinacridone pigment was used.

Example 4
In Example 3, an aqueous dispersion of pigment-containing vinyl polymer particles was prepared in the same manner as in Example 3 except that the polymer solution obtained in Production Example 2 was used instead of the polymer solution obtained in Production Example 1. Obtained.

Comparative Example 1
In Example 1, water dispersion of pigment-containing vinyl polymer particles was performed in the same manner as in Example 1 except that the polymer solution obtained in Comparative Production Example 1 was used instead of the polymer solution obtained in Production Example 1. Got the body.

Comparative Example 2
In Example 1, instead of the polymer solution obtained in Production Example 1, a water-soluble polymer (manufactured by Johnson Polymer Co., Ltd., trade name: Jonkrill 62, weight average molecular weight 8500) was used, and a neutralizing agent (20% water) An aqueous pigment dispersion was obtained in the same manner as in Example 1 except that the aqueous sodium oxide solution was not added.

(Preparation of water-based ink)
Example 5
40 parts of an aqueous dispersion of pigment-containing vinyl polymer particles obtained in Example 1, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), Surfynol 465 (activator, manufactured by Nissin Chemical Industry Co., Ltd.) 1 Part, 0.3 parts of Proxel XL2 (preservative, manufactured by Avicia Co., Ltd.) and 41.7 parts of ion-exchanged water were mixed, and the resulting mixture was mixed with a 25 mL needleless syringe equipped with a 1.2 μm filter. Filtration was performed to remove coarse particles, and an aqueous ink was prepared.

Examples 6-8
A water-based ink was prepared in the same manner as in Example 5 except that the aqueous dispersion of pigment-containing vinyl polymer particles used in the water-based ink was changed to that obtained in the production example shown in Table 2. .

Comparative Example 3
In Example 5, a water-based ink was prepared in the same manner as in Example 5 except that the aqueous dispersion of the pigment-containing vinyl polymer particles used in the water-based ink was changed to that obtained in Comparative Example 1 in Table 3. .

Comparative Example 4
In Example 5, a water-based ink was prepared in the same manner as in Example 5 except that the aqueous dispersion of pigment-containing vinyl polymer particles used in the water-based ink was changed to that obtained in Comparative Example 2 of Table 3. .

Next, the performance of the aqueous ins obtained in Examples 5 to 8 and Comparative Examples 3 to 4 was evaluated by the following methods. The results are shown in Table 6.
(1) Ejectability Solid printing (mode setting: KA4250NT) on plain paper [double-sided plain plain paper, Seiko Epson Corporation, trade name: KA4250NT] using an ink jet printer (model number: EM-930C) manufactured by Seiko Epson Corporation. The ink dischargeability was evaluated according to the following evaluation criteria.
○: Good ejection at all nozzles △: Some nozzles have poor ejection ×: Discharge defective

(2) Dispersion stability Using a laser particle analysis system ELS-8000 manufactured by Otsuka Electronics Co., Ltd., the “average particle diameter before storage” of the polymer particles containing the colorant contained in the ink was measured. The ink was put in a sealed container, stored in a thermostat at 60 ° C. for 1 month, and “average particle diameter after storage” was measured by the same method. As an index of dispersion stability, dispersion stability was determined by the following formula and evaluated according to the following evaluation criteria.
Dispersion stability (%) = ([average particle size after storage] / [average particle size before storage]) × 100
◯: Dispersion stability is 95% or more and less than 105% Δ: Dispersion stability is 85% or more and less than 95%, or 105% or more and less than 115% ×: Dispersion stability is less than 85% or 115% or more

(3) Print Density Solid printing is performed on plain paper under the same conditions as in (1) above, and the print density is measured with a Macbeth densitometer (product number: RD914, manufactured by Gretag Macbeth Co., Ltd.) at 25 ° C (25 ° C). did.
The evaluation of the print density is preferably 1.1 or more, and more preferably 1.2 or more.

(4) Glossiness Using the printer described in (1) above, solid printing (mode: photo) on special paper [Seiko Epson Corporation, trade name: KA450PSK, photo paper (glossy)] and leaving at 25 ° C. for 1 day Then, the glossiness was measured (25 ° C.) with a gloss meter (manufactured by Nippon Denka Kogyo Co., Ltd., product number: PG-1M, measurement angle 60 °).
The gloss evaluation is preferably 50 or more, more preferably 60 or more.

(5) Fixability Solid prints were made on special paper under the same conditions as in (4) above, left at 25 ° C. for 1 day, and rubbed with a finger. Fixability was confirmed using the following evaluation indices.
◎: There is no stain on the printed part. ○: There is almost no stain on the printed part. △: There is a little stain on the printed part. ×: There is dirt on the printed part. ○ or more is preferable.

From the results shown in Table 6, the water-based inks of Examples 5 to 8 are superior in dispersion stability, have higher print density on plain paper, and have glossiness on dedicated paper than the water-based inks of Comparative Examples 3 and 4. It can be seen that a printed matter having excellent fixability can be obtained.

Claims (8)

An aqueous dispersion of water-insoluble vinyl polymer particles containing a quinacridone pigment (A) and a pigment derivative (B) obtained by introducing an acidic group into an organic pigment, wherein the water-insoluble vinyl polymer has the following formula (1) An aqueous dispersion for inkjet recording having a structural unit represented by:

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an arylalkyl group having 7 to 22 carbon atoms or an aryl group having 6 to 22 carbon atoms, which may have a substituent. )   The aqueous dispersion for inkjet recording according to claim 1, wherein the pigment derivative (B) is 0.5 to 20 parts by weight with respect to 100 parts by weight of the quinacridone pigment (A).   The quinacridone pigment (A) is C.I. I. Pigment red 122 and / or C.I. I. The aqueous dispersion for inkjet recording according to claim 1 or 2, which is CI Pigment Violet 19, and the pigment derivative (B) has a quinacridone skeleton.   The aqueous dispersion for inkjet recording according to any one of claims 1 to 3, wherein the acidic group of the pigment derivative (B) is a sulfonic acid group.   The water dispersion for inkjet recording according to any one of claims 1 to 4, wherein the water-insoluble vinyl polymer contains 10 to 80% by weight of the structural unit represented by the formula (1).   The aqueous dispersion for inkjet recording according to any one of claims 1 to 5, wherein the structural unit represented by the formula (1) is a structural unit derived from benzyl (meth) acrylate.   The water dispersion for inkjet recording according to any one of claims 1 to 6, wherein the water-insoluble vinyl polymer has a weight average molecular weight of 5,000 to 500,000. An aqueous ink for ink-jet recording, comprising the water dispersion according to claim 1.