JP7067161B2 - Ink, ink container, recording device, and recording method - Google Patents

Description

The present invention relates to ink, an ink container, a recording device, and a recording method.

As the ink used in the inkjet recording method, an ink using a dye or a pigment is known. In such inks, inks using pigments are widely used from the viewpoint of weather resistance and water resistance. Further, in recent years, the development of pigment inks for high-speed continuous book machines has been promoted, and there is a demand for pigment inks that can obtain high-quality images even when printed at high speed. In a high-speed continuous business machine, the main target medium may be offset coated paper (also referred to as coated paper), and this offset coated paper obtains high image quality when pigment ink is used. The mechanism for this is different from that of plain paper. Further, such pigment inks often contain resin particles for the purpose of improving the fixability of the image formed by applying the ink to the recording medium and the storage stability of the ink.

Patent Document 1 discloses that an ink containing water, a coloring material and a predetermined copolymer further contains styrene acrylic resin particles.

Patent Document 2 discloses that a black ink composition containing water, carbon black, and a water-soluble polyurethane resin further contains a fine particle emulsion.

However, for example, there is a problem that the image density is lowered when the image formed by applying the pigment ink containing the resin particles to a recording medium such as coated paper is heated. On the other hand, when the resin particles are not contained in the pigment ink, the decrease in image density due to heating is suppressed, but there is a problem that the fixability of the image to the recording medium and the storage stability of the pigment ink are deteriorated. Therefore, it has been difficult to achieve both image density and fixability and storage stability.

（上記一般式（１）中、Ｒ^１は水素原子またはメチル基を表し、Ａ_１、Ａ_２、及びＡ_３はそれぞれ独立して－Ｏ－、－ＣＯ－Ｏ－、－Ｏ－ＣＯ－、－ＣＯ－ＮＨ－、－ＮＨ－ＣＯ－、－ＮＨ－ＣＯ－Ｏ－、－Ｏ－ＣＯ－ＮＨ－の群から選ばれる２価の置換基を表し、Ｘ_１、及びＸ_２はそれぞれ独立して炭素数１以上１２以下のアルキレン基、炭素数１以上１２以下のアルケニレン基、一般式（４）、一般式（５）、及び一般式（６）の群から選ばれる２価の置換基を表し、Ａｒはナフチル基を表す。）

（上記一般式（２）中、Ｒ^１、Ａ_１、Ａ_２、Ｘ_１、Ｘ_２、及びＡｒはそれぞれ独立して一般式（１）と同じものを表す。）

（上記一般式（３）中、Ｒ^１、Ａ_１、Ａ_２、Ａ_３、Ｘ_１、Ｘ_２、及びＡｒはそれぞれ独立して一般式（１）と同じものを表し、Ａ_４は－Ｏ－、－ＣＯ－Ｏ－、－Ｏ－ＣＯ－、－ＣＯ－ＮＨ－、－ＮＨ－ＣＯ－、－ＮＨ－ＣＯ－Ｏ－、－Ｏ－ＣＯ－ＮＨ－の群から選ばれる２価の置換基を表し、Ｚは２価の炭化水素基を表す。）

（上記一般式（４）中、ｌは１以上１０以下の整数を表す。）

（上記一般式（５）中、ｍは１以上１０以下の整数を表す。）

（上記一般式（６）中、ｎは１以上１０以下の整数を表す。）
The invention according to claim 1 contains water, a pigment, a copolymer, and a water-soluble polyester, and the copolymer is a structural unit represented by any one of the following general formulas (1) to (3). And an ink having a structural unit having an anionic functional group.

(In the above general formula (1), R ¹ represents a hydrogen atom or a methyl group, and A ₁ , A ₂ , and A ₃ are independently -O-, -CO-O-, and -O-CO-, respectively. Represents a divalent substituent selected from the group of -CO-NH-, -NH-CO-, -NH-CO-O-, -O-CO-NH-, and X ₁ and X ₂ are independent of each other. An alkylene group having 1 to 12 carbon atoms, an alkenylene group having 1 to 12 carbon atoms, and a divalent substituent selected from the group of the general formula (4), the general formula (5), and the general formula (6). Ar represents a naphthyl group .)

(In the above general formula (2), R ¹ , A ₁ , A ₂ , X ₁ , X ₂ , and Ar each independently represent the same as the general formula (1).)

(In the above general formula (3), R ¹ , A ₁ , A ₂ , A ₃ , X ₁ , X ₂ , and Ar each independently represent the same as the general formula (1), and A ₄ is -O. -, -CO-O-, -O-CO-, -CO-NH-, -NH-CO-, -NH-CO-O-, -O-CO-NH-divalent substitution selected from the group Represents a group, where Z represents a divalent hydrocarbon group.)

(In the above general formula (4), l represents an integer of 1 or more and 10 or less.)

(In the above general formula (5), m represents an integer of 1 or more and 10 or less.)

(In the above general formula (6), n represents an integer of 1 or more and 10 or less.)

The present invention has an excellent effect of achieving both image density, fixability and storage stability.

FIG. 1 is a perspective explanatory view of a recording device. FIG. 2 is a perspective explanatory view of the main tank.

Hereinafter, an embodiment of the present invention will be described.

<< Ink >>
Hereinafter, copolymers, organic solvents, water, pigments, resins, additives and the like used for ink will be described.

<Copolymer>
The copolymer contained in the ink has a structural unit represented by any one of the general formulas (1) to (3) and a structural unit having an anionic functional group, and further, if necessary. Includes other structural units.

一般式（１）中、Ｒ^１は水素原子またはメチル基を表す。Ａ_１、Ａ_２、及びＡ_３はそれぞれ独立して－Ｏ－、－ＣＯ－Ｏ－、－Ｏ－ＣＯ－、－ＣＯ－ＮＨ－、－ＮＨ－ＣＯ－、－ＮＨ－ＣＯ－Ｏ－、－Ｏ－ＣＯ－ＮＨ－の群から選ばれる２価の置換基を表す。Ｘ_１、及びＸ_２はそれぞれ独立して単結合、炭素数１以上１２以下のアルキレン基、炭素数１以上１２以下のアルケニレン基、一般式（４）、一般式（５）、及び一般式（６）の群から選ばれる２価の置換基を表す。Ａｒは芳香族基を表し、特に制限はなく、目的に応じて適宜選択することができ、例えば、ベンゼン環、縮合ベンゼン環、非ベンゼン系芳香環、複合芳香環などが挙げられる。具体的には、例えば、フェニル基、トリル基、キシリル基、ナフチル基、メチルナフチル基、アントリル基、フェナントレニル基、ビフェニル基、ピリジニル基、トリアジニル基、フェナンスリル基、ピレニル基、フルオレニル基などが挙げられる。 -Structural unit represented by the general formula (1)-

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group. A ₁ , A ₂ and A ₃ are independently -O-, -CO-O-, -O-CO-, -CO-NH-, -NH-CO-, -NH-CO-O-, respectively. Represents a divalent substituent selected from the group -O-CO-NH-. X ₁ and X ₂ are independently single bonds, an alkylene group having 1 or more and 12 or less carbon atoms, an alkenylene group having 1 or more and 12 or less carbon atoms, a general formula (4), a general formula (5), and a general formula ( Represents a divalent substituent selected from the group of 6). Ar represents an aromatic group and is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a benzene ring, a condensed benzene ring, a non-benzene aromatic ring and a composite aromatic ring. Specific examples thereof include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a methylnaphthyl group, an anthryl group, a phenanthrenyl group, a biphenyl group, a pyridinyl group, a triazinyl group, a phenanthryl group, a pyrenyl group and a fluorenyl group. ..

一般式（４）中、ｌは１以上１０以下の整数を表す。

In the general formula (4), l represents an integer of 1 or more and 10 or less.

一般式（５）中、ｍは１以上１０以下の整数を表す。

In the general formula (5), m represents an integer of 1 or more and 10 or less.

一般式（６）中、ｎは１以上１０以下の整数を表す。

In the general formula (6), n represents an integer of 1 or more and 10 or less.

一般式（２）中、Ｒ^１、Ａ_１、Ａ_２、Ｘ_１、Ｘ_２、及びＡｒはそれぞれ独立して一般式（１）と同じものを表す。 -Structural unit represented by the general formula (2)-

In the general formula (2), R ¹ , A ₁ , A ₂ , X ₁ , X ₂ , and Ar independently represent the same as the general formula (1).

一般式（３）中、Ｒ^１、Ａ_１、Ａ_２、Ａ_３、Ｘ_１、Ｘ_２、及びＡｒはそれぞれ独立して一般式（１）と同じものを表す。Ａ_４は－Ｏ－、－ＣＯ－Ｏ－、－Ｏ－ＣＯ－、－ＣＯ－ＮＨ－、－ＮＨ－ＣＯ－、－ＮＨ－ＣＯ－Ｏ－、－Ｏ－ＣＯ－ＮＨ－の群から選ばれる２価の置換基を表す。Ｚは２価の炭化水素基を表し、例えば、脂肪族炭化水素基、環式脂肪族炭化水素基、芳香族炭化水素基などが挙げられ、炭素数２以上１５以下のアルキレン基、炭素数２以上１５以下のアルケニレン基、炭素数３以上１５以下の環式飽和炭化水素基、炭素数３以上１５以下の環式不飽和炭化水素基、炭素数６以上１５以下のアリーレン基などが好ましい。 -Structural unit represented by the general formula (3)-

In the general formula (3), R ¹ , A ₁ , A ₂ , A ₃ , X ₁ , X ₂ , and Ar each independently represent the same as the general formula (1). A4 is selected from the group of -O-, -CO _- O-, -O-CO-, -CO-NH-, -NH-CO-, -NH-CO-O-, -O-CO-NH-. Represents a divalent substituent. Z represents a divalent hydrocarbon group, and examples thereof include an aliphatic hydrocarbon group, a cyclic aliphatic hydrocarbon group, an aromatic hydrocarbon group, and the like, an alkylene group having 2 or more and 15 or less carbon atoms, and 2 carbon atoms. Preferable are an alkenylene group having 15 or more carbon atoms, a cyclic saturated hydrocarbon group having 3 or more and 15 carbon atoms, a cyclic unsaturated hydrocarbon group having 3 or more carbon atoms and 15 or less carbon atoms, and an arylene group having 6 or more and 15 carbon atoms or less.

Hereinafter, structural units represented by any of the general formulas (1) to (3) will be illustrated.

The aromatic group represented by Ar existing at the end of the general formula (1), the general formula (2), and the general formula (3) is excellent due to π-π stacking with the pigment which is the coloring material in the ink. Has the ability to adsorb pigments. When the above-mentioned copolymer is used when preparing a pigment dispersion in which a pigment is dispersed in water, the adsorptivity with the pigment is high, so that the dispersion stability is high and a dispersion with high storage stability can be obtained. Further, even when a hydrophilic organic solvent is added to the ink, the dispersibility is maintained, and an ink having high storage stability can be obtained.

The content of the structural unit represented by any one of the general formulas (1) to (3) is not particularly limited and may be appropriately selected depending on the intended purpose, but with respect to the total amount of the copolymer. , 30% by mass or more and 80% by mass or less is preferable, and 40% by mass or more and 70% by mass or less is more preferable. When the content is within a preferable range, it is advantageous in that the image density and storage stability are good when used in ink.

一般式（７）中、Ｒ^２は水素原子またはメチル基を表し、Ｌは炭素数２以上１６以下のアルキレン基を表す。以下、一般式（７）の構造単位を形成するモノマーの具体例を挙げるがこれらに限定されるわけではない。

Further, the structural unit represented by any one of the general formulas (1) to (3) is preferably the structural unit represented by the general formula (7) below.

In the general formula (7), R ² represents a hydrogen atom or a methyl group, and L represents an alkylene group having 2 or more carbon atoms and 16 or less carbon atoms. Hereinafter, specific examples of the monomers forming the structural unit of the general formula (7) will be given, but the present invention is not limited thereto.

In the general formula (7), polar groups such as -CO-O- group and -NH-CO- group contained in the structural unit are located in the structural unit in a well-balanced manner, while maintaining sufficient adsorptivity with the pigment. , The dispersed state can be stably maintained even in the solvent used for the ink.

-Structural unit with anionic functional group-
The structural unit having an anionic functional group is formed by copolymerizing a monomer having an anionic functional group. Examples of the monomer having an anionic functional group include an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer. These monomers having anionic functional groups may be used alone or in combination of two or more.
Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and the like.
Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid and 2-acrylamide-2-methylpropane sulfonic acid.
Examples of the unsaturated phosphoric acid monomer include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, and dibutyl-2-acry. Examples thereof include leuroxyethyl phosphate.

Further, the structural unit having an anionic functional group may be neutralized with a base.
Examples of the base include sodium hydroxide, potassium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide. , Triethylmethylammonium hydroxide, tributylmethylammonium hydroxide, trioctylmethylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, tris (2-hydroxyethyl) methylammonium hydroxide, propyltrimethylammonium hydroxide, hexyltrimethylammonium Hydroxide, Octyltrimethylammonium Hydroxide, Nonyltrimethylammonium Hydroxide, Decyltrimethylammonium Hydroxide, Dodecyltrimethylammonium Hydroxide, Tetradecyltrimethylammonium Hydroxide, Hexadecyltrimethylammonium Hydroxide, Octadecyltrimethylammonium Hydroxide, Didodecyldimethyl Ammonium hydroxide, ditetradecyldimethylammonium hydroxide, dihexadecyldimethylammonium hydroxide, dioctadecyldimethylammonium hydroxide, ethylhexadecyldimethylammonium hydroxide, aqueous ammonia, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, Monoethanolamine, diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, dimethylethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, morpholine, N-methylmorphone, N-methyl-2-pyrrolidone, 2-Pyrrolidone and the like can be mentioned.
The base as a neutralizing agent may be used alone or in combination of two or more. The neutralization treatment may be carried out when copolymerizing a monomer having an anionic functional group or when dissolving the copolymer.

The content of the structural unit having an anionic functional group is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30% by mass or more and 80% by mass or less with respect to the total amount of the copolymer. , 40% by mass or more and 70% by mass or less is more preferable.

Further, the molar ratio of the structural unit represented by any one of the general formulas (1) to (3) and the structural unit having an anionic functional group is not particularly limited and is appropriate depending on the purpose. It can be selected, but it can be selected from the viewpoint of the balance between hydrophilicity and hydrophobicity of the copolymer, image density, and storage stability. For example, from the viewpoint of storage stability, "1.0: 1.2 to 1.0: 2.0" is preferable. Further, from the viewpoint of image density, "1.0: 1.5 to 1.0: 2.5" is preferable. Therefore, the molar ratio of the structural unit represented by any one of the general formulas (1) to (3) and the structural unit having an anionic functional group is "1.0: 1.5 to 1". .0: 2.0 "is the most preferable.

一般式（８）中、Ｒ^３は水素原子またはメチル基を表し、Ｘは水素原子又は陽イオンを表す。 Further, as the structural unit having an anionic functional group, it is preferable to have a structural unit represented by the general formula (8).

In the general formula (8), R ³ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom or a cation.

When X is a cation, the oxygen adjacent to the cation exists as O ⁻ . The cations include sodium ion, potassium ion, lithium ion, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, triethylmethylammonium ion, and tributylmethyl. Ammonium ion, trioctylmethylammonium ion, 2-hydroxyethyltrimethylammonium ion, tris (2-hydroxyethyl) methylammonium ion, propyltrimethylammonium ion, hexyltrimethylammonium ion, octyltrimethylammonium ion, nonyltrimethylammonium ion, decyltrimethyl Ammonium ion, dodecyltrimethylammonium ion, tetradecyltrimethylammonium ion, hexadecyltrimethylammonium ion, octadecyltrimethylammonium ion didodecyldimethylammonium ion, ditetradecyldimethylammonium ion, dihexadecyldimethylammonium ion, dioctadecyldimethylammonium ion, Ethylhexadecyldimethylammonium ion, ammonium ion, dimethylammonium ion, trimethylammonium ion, monoethylammonium ion, diethylammonium ion, triethylammonium ion, monoethanolammonium ion, diethanolammonium ion, triethanolammonium ion, methylethanolammonium ion, Methyldiethanolammonium ion, dimethylethanolammonium ion, monopropanolammonium ion, dipropanolammonium ion, tripropanolammonium ion, isopropanolammonium ion, morpholinium ion, N-methylmorpholinium ion, N-methyl-2-pyrrolidoni Ammonium ion, 2-pyrrolidnium ion and the like can be mentioned. It is preferable that X is hydrogen in terms of reactivity with cations derived from cationic substances such as calcium ions contained in paper.

Further, the monomer forming the general formula (8) is preferably a monomer having a carboxyl group, and more preferably acrylic acid or methacrylic acid, in terms of storage stability of the ink.

-Other structural units-
In addition to the structural unit represented by any one of the general formulas (1) to (3) and the structural unit having an anionic functional group, the copolymer further contains other structural units as necessary. include.
The other structural unit is, for example, a structural unit derived from a polymerizable hydrophobic monomer, a polymerizable hydrophilic monomer, a polymerizable surfactant, or the like.

（反応式２）

また別の方法としては、先に（Ａ－１）と（Ａ－４）を反応させた後、（Ａ－２）と反応させて、一般式（１）で表される構造単位の元となるモノマーを得ることができる。
さらに別の方法としては、下記反応式３に示すように、ジイソシアネート化合物（Ａ－１）、ナフトール（Ａ－２）、ヒドロキシアルキルメタクリレート（Ａ－４）を反応させ、一般式（１）で表される構造単位の元となるモノマーを得ることもできる。
（反応式３）

-Method for synthesizing a copolymer containing a structural unit represented by the general formula (1)-
The copolymer containing the structural unit represented by the general formula (1) is obtained by copolymerizing a monomer which is a source of the structural unit represented by the general formula (1), a monomer having an anionic functional group, or the like. can get.
As an example, the monomer that is the source of the structural unit represented by the general formula (1) can be synthesized and used as follows. That is, as shown in the following reaction formulas 1 and 2, first, the diisocyanate compound (A-1) and naphthol (A-2) are reacted in the presence of an acid receptor such as amine or pyridine to form a reaction intermediate. (A-3) is obtained. Next, the hydroxyalkyl methacrylate (A-4) and (A-3) can be reacted to obtain a monomer that is the source of the structural unit represented by the general formula (1).
(Reaction formula 1)

(Reaction formula 2)

As another method, (A-1) and (A-4) are first reacted, and then (A-2) is reacted with the element of the structural unit represented by the general formula (1). Can be obtained.
As yet another method, as shown in the following reaction formula 3, the diisocyanate compound (A-1), naphthol (A-2), and hydroxyalkyl methacrylate (A-4) are reacted and represented by the general formula (1). It is also possible to obtain the monomer that is the basis of the structural unit to be formed.
(Reaction equation 3)

As a method for synthesizing a copolymer containing a structural unit represented by the general formula (1), a method using a radical polymerization initiator is preferable because it is easy to carry out a polymerization operation and adjust the molecular weight, and the polymerization reaction is carried out in a solution. The solution polymerization method to be carried out is more preferable.
Preferred solvents for radical polymerization by the solution polymerization method are ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, acetate solvents such as ethyl acetate and butyl acetate, and aromatic carbonization such as benzene, toluene and xylene. Examples thereof include hydrogen-based solvents, isopropanol, ethanol, cyclohexane, tetrahydrofuran, dimethylformamide, dimethylsulfoxide and hexamethylphosphoamide, and more preferably, ketone-based solvents, acetate-based solvents and alcohol-based solvents.
The radical polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, cyano-based azobisisobutyronitrile, and azobis (2-methylbutyronitrile). Examples thereof include azobis (2,2'-isovaleronitrile), non-cyano dimethyl-2,2'-azobisisobutyrate, and the like. Among these, organic peroxides and azo compounds are preferable, and azo compounds are particularly preferable, because the molecular weight can be easily controlled and the decomposition temperature is low.
The content of the radical polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 to 10% by mass with respect to the total amount of the polymerizable monomer.
Chain transfer agents may be added in appropriate amounts to adjust the molecular weight of the polymer.
Examples of chain transfer agents include mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, dodecyl mercaptan, 1-dodecanethiol, thioglycerol, and the like.
The polymerization temperature is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50 ° C to 150 ° C, more preferably 60 ° C to 100 ° C. The polymerization time is also not particularly limited and may be appropriately selected depending on the intended purpose, but 3 to 48 hours is preferable.

また別の方法としては、下記反応式５に示すように、カルボキシル基を有するナフタレン誘導体の酸塩化物（Ｂ－４）と、ジオール化合物（Ｂ－１）を、アミン又はピリジンなどの酸受容体の存在下で反応させて、反応中間体（Ｂ－３）を得ることもできる。
（反応式５）

次いで、下記反応式６に示すように、（メタ）アクリル酸クロリド（Ｂ－５）と（Ｂ－３）とを反応させて、一般式（２）で表される構造単位の元となるモノマーを得ることもできる。
（反応式６）

-Method for synthesizing a copolymer containing a structural unit represented by the general formula (2)-
The copolymer containing the structural unit represented by the general formula (2) is obtained by copolymerizing a monomer which is a source of the structural unit represented by the general formula (2), a monomer having an anionic functional group, or the like. can get.
As an example, the monomer that is the source of the structural unit represented by the general formula (2) can be synthesized and used as follows. That is, as shown in Reaction Scheme 4 below, first, the diol compound (B-1) and the naphthalene derivative (B-2) having a carboxyl group are reacted in the presence of an acid catalyst to react with the reaction intermediate (B-3). ).
(Reaction equation 4)

As another method, as shown in the following reaction formula 5, an acid chloride (B-4) of a naphthalene derivative having a carboxyl group and a diol compound (B-1) are used as an acid acceptor such as an amine or pyridine. The reaction intermediate (B-3) can also be obtained by reacting in the presence of.
(Reaction equation 5)

Next, as shown in the reaction formula 6 below, the (meth) acrylic acid chloride (B-5) and (B-3) are reacted to form a monomer that is the basis of the structural unit represented by the general formula (2). You can also get.
(Reaction equation 6)

As a method for synthesizing the copolymer containing the structural unit represented by the general formula (2), the same method as the method for synthesizing the copolymer containing the structural unit represented by the general formula (1) is preferable.

（反応式８）

（反応式９）

また別の方法としては、先に（Ｃ－４）と（Ｃ－６）を反応させた後、（Ｃ－１）、（Ｃ－２）と次いで反応させる方法、先に（Ｃ－１）と（Ｃ－２）を反応させて得られた中間体と、別途、（Ｃ－４）と（Ｃ－６）を反応させて得られた中間体とを反応させる方法などにより、一般式（３）で表されるモノマーを得ることができるが、（Ｃ－１）、（Ｃ－２）、（Ｃ－４）、（Ｃ－６）を反応させる順番に特に制限はない。
さらに別の方法としては、下記反応式１０に示すように、ジオール化合物（Ｃ－１）、ナフタレン酸化合物（Ｃ－２）、ジイソシアネート化合物（Ｃ－４）、ヒドロキシアルキル（メタ）アクリレート（Ｃ－６）を反応させ、一般式（３）で表されるモノマーを得ることもできる。
（反応式１０）

-Method for synthesizing a copolymer containing a structural unit represented by the general formula (3)-
The copolymer containing the structural unit represented by the general formula (3) is obtained by copolymerizing a monomer which is a source of the structural unit represented by the general formula (3), a monomer having an anionic functional group, or the like. can get.
As an example, the monomer that is the source of the structural unit represented by the general formula (3) can be synthesized and used as follows. That is, as shown in the following reaction formulas 7 to 9, first, the diol compound (C-1) and the naphthalene acid compound (C-2) are condensed to obtain a reaction intermediate (C-3). The diisocyanate compounds (C-4) and (C-3) are then reacted in the presence of an acid acceptor such as amine or pyridine or in the presence of a metal catalyst such as tin or titanium to react with the reaction intermediate (C). -5) is obtained. Next, the hydroxyalkyl (meth) acrylate (C-6) and (C-5) can be reacted to obtain a monomer represented by the general formula (3).
The compound represented by (C-2) is not particularly limited as long as it is a naphthalene acid compound capable of condensing with a hydroxy group, and the group represented by L is a carboxylic acid such as a hydroxy group or an alkoxide group or a carboxylic acid ester. Examples thereof include, but are not limited to, halogen-based desorbing groups such as chlorine, bromine, and fluorine, or desorbing groups such as tosyl group, mesyl group, and ammonium ion.
(Reaction equation 7)

(Reaction equation 8)

(Reaction equation 9)

Another method is to first react (C-4) and (C-6) and then react with (C-1) and (C-2), and then (C-1). The general formula ( The monomer represented by 3) can be obtained, but the order in which (C-1), (C-2), (C-4) and (C-6) are reacted is not particularly limited.
As yet another method, as shown in Reaction Scheme 10 below, a diol compound (C-1), a naphthalene acid compound (C-2), a diisocyanate compound (C-4), and a hydroxyalkyl (meth) acrylate (C-). 6) can be reacted to obtain a monomer represented by the general formula (3).
(Reaction equation 10)

As a method for synthesizing the copolymer containing the structural unit represented by the general formula (3), the same method as the method for synthesizing the copolymer containing the structural unit represented by the general formula (1) is preferable.

-Physical characteristics of copolymer-
The weight average molecular weight of the copolymer is preferably 5000 to 50,000 in terms of polystyrene. More preferably, it is 15,000 to 40,000. When the weight average molecular weight is within a preferable range, it is advantageous in that the image density and the storage stability are good when used in an ink.

-Amount of copolymer added-
The amount of the above-mentioned copolymer added to the total amount of ink is not particularly limited and may be appropriately selected depending on the intended purpose. However, the solid content is preferably 0.05% by mass or more and 10.0% by mass or less, and 0. More preferably, it is 3% by mass or more and 5.0% by mass or less. When the content is 0.05% by mass or more, the effects of dispersibility and storage stability are improved, and when it is 10.0% by mass or less, the viscosity range suitable for ejecting ink from the head is set. Is possible.
Further, the copolymer is not particularly limited and can be used as a pigment dispersant or as an additive to a pigment dispersion. When used as a pigment dispersant, further improvement in storage stability is observed in inks having a high content of water-soluble organic solvents. The content of the copolymer is not particularly limited when used as a pigment dispersant, and can be appropriately selected depending on the intended purpose. For example, 1 part by mass or more and 100 parts by mass or less are preferable, and 5 parts by mass or more and 80 parts by mass or less are more preferable with respect to 100 parts by mass of the pigment. When the content is within the above range, it is advantageous in that the image density and storage stability are good. In addition, other dispersants may be used in combination as long as the effect of the copolymer as a dispersant is not impaired.

<Resin>
The ink of this embodiment contains a resin, and the resin is a water-soluble polyester. The term "water-soluble" in the water-soluble polyester means that it dissolves in water in an amount of 10% by mass or more at room temperature (25 ° C.). By using the water-soluble polyester and the above-mentioned copolymer in combination, for example, even when the image formed by applying the pigment ink to a recording medium such as coated paper is heated, the image after heating is used. It is possible to suppress the decrease in image density. This will be described below.
Generally, as a recording medium, plain paper having high water and ink absorbency, coated paper having low water and ink absorbency, and the like are known. When trying to obtain an image having a high image density on these recording media, if the plain paper is used, the pigment is excessively penetrated into the plain paper to prevent the image density from being lowered. Design an ink that can be kept near the surface of the recording medium. On the other hand, in the case of coated paper, the pigment penetrates excessively into the inside of the coated paper, and the image density is less likely to decrease as compared with plain paper. Ink design is performed to improve the image density by making the dispersed state (surface shape of the image portion) uniform.
However, even if the present inventors improve the image density by making the dispersed state of the pigment uniform in the image formed by applying the ink, the image unit is subsequently dried for the purpose of drying the image unit or the like. It was discovered that when the ink is heated, the dispersed state of the pigment in the image portion changes and the image density decreases. As a result of various studies, it has been found that the dispersed state of the image portion is changed by the resin emulsion which is often contained in the ink during heating, and the image density is lowered.
On the other hand, when the resin particles are not contained in the ink, the decrease in image density due to heating is suppressed, but there is a problem that the fixability of the image to the recording medium and the storage stability of the ink are deteriorated. Further, when a water-soluble resin is used instead of the resin particles in order to improve the fixability, the storage stability of the ink is lowered.
Therefore, when the above-mentioned copolymer having a specific structure for improving the storage stability of the ink is used in combination with the water-soluble polyester resin, the change in the dispersed state of the pigment in the image portion is suppressed even if the image portion is heated, and the image is imaged. It has been found that an ink having an excellent effect of achieving both density, fixability and storage stability can be obtained. In particular, when a water-soluble polyester resin having a low Tg is used, it is preferable because the fixability is improved even if the content of the water-soluble polyester resin is small, and the storage stability can be further improved.
When a water-soluble polyurethane resin or the like is used instead of the water-soluble polyester resin, the Tg of these resins is generally low, so that the surface roughness Ra of the image portion becomes large even without going through the heating step. The image density becomes low from the beginning. Therefore, the type of water-soluble resin needs to be polyester resin.

As the water-soluble polyester, a commercially available polyester can be appropriately used, and examples thereof include Plus Coat (manufactured by Goo Chemical Co., Ltd.).
The Tg of the water-soluble polyester is preferably −20 ° C. or higher and 110 ° C. or lower, and more preferably −20 ° C. or higher and 20 ° C. or lower. In particular, when Tg is −20 ° C. or higher and 20 ° C. or lower, sufficient fixing property and storage stability can be obtained even if the amount of the water-soluble polyester added is small.
The content of the water-soluble polyester is preferably 0.1% by mass or more and 2.0% by mass or less, more preferably 0.5% by mass or more and 1.2% by mass or less, based on the total amount of the ink. It is more preferably 0.5% by mass or more and 0.8% by mass or less. When the content of the water-soluble polyester is 2.0% by mass or less, the storage stability is improved, and when it is 0.1% by mass or more, the fixability is improved.
The mass ratio (water-soluble polyester / copolymer) of the content of the water-soluble polyester in the ink to the content of the copolymer in the ink is preferably 0.13 or more and 2.67 or less. , 0.67 or more and 1.60 or less is more preferable. Within this range, it is possible to achieve both image density, fixability and storage stability in a well-balanced manner.

The present embodiment does not exclude the ink from containing the resin emulsion, but preferably does not substantially contain the resin emulsion from the ink. By substantially not containing the resin emulsion in the ink, it is possible to further suppress the decrease in image density. In addition, "substantially not contained" means that the content of the resin emulsion with respect to the total amount of ink is 0.1% by mass or less. Further, it is preferable that the ink does not contain any resin emulsion.

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines and sulfur-containing compounds.
Specific examples of polyhydric alcohols include, for example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol , 2,4-Pentanediol, 1,5-Pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, Glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl- Examples thereof include 1,3-pentanediol and petriol.
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether.
Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone. Can be mentioned.
Examples of the amides include formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide and the like.
Examples of amines include monoethanolamine, diethanolamine, triethylamine and the like.
Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol.
Examples of other organic solvents include propylene carbonate and ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also has good drying properties.

As the organic solvent, a polyol compound having 8 or more carbon atoms and a glycol ether compound are also preferably used. Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of the glycol ether compound include polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers; Examples thereof include polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

A polyol compound having 8 or more carbon atoms and a glycol ether compound can improve the permeability of ink when paper is used as a recording medium.

The content of the organic solvent in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 60% by mass or less from the viewpoint of ink drying property and ejection reliability. More preferably, it is 20% by mass or more and 60% by mass or less.

<Water>
The content of water in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of ink drying property and ejection reliability, it is preferably 10% by mass or more and 90% by mass or less, and 20% by mass. % Or more and 60% by mass or less are more preferable.

<Pigment>
As the pigment, an inorganic pigment or an organic pigment can be used. These may be used alone or in combination of two or more. Further, a mixed crystal may be used as the pigment.
As the pigment, for example, a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, a white pigment, a green pigment, an orange pigment, a glossy color pigment such as gold or silver, a metallic pigment, or the like can be used.
As inorganic pigments, carbon black produced by known methods such as contact method, furnace method, thermal method, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow. Can be used.
Examples of organic pigments include azo pigments and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.). , Dye chelate (for example, basic dye type chelate, acid dye type chelate, etc.), nitro pigment, nitroso pigment, aniline black and the like can be used. Among these pigments, those having a good affinity with a solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
As a specific example of the pigment, for black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (CI pigment black 11) , Metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).
Further, for color, C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Calcium 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment Violet 1 (Rhodamine Lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3, 15: 4 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Greens 1, 4, 7, 8, 10, 17, 18, 36, etc.

The content of the pigment in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less, from the viewpoint of improving the image density, good fixing property and ejection stability. Is.

As a method of dispersing the pigment to obtain an ink, a method of introducing a hydrophilic functional group into the pigment to obtain a self-dispersible pigment, a method of coating the surface of the pigment with a resin and dispersing it, and a method of dispersing using a dispersant are used. The method, etc. can be mentioned.
As a method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersing pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon) so that the pigment can be dispersed in water. Can be mentioned.
Examples of the method of coating the surface of the pigment with a resin and dispersing the pigment include a method of encapsulating the pigment in microcapsules so that the pigment can be dispersed in water. This can be rephrased as a resin-coated pigment. In this case, it is not necessary that all the pigments blended in the ink are coated with the resin, and the uncoated pigments and the partially coated pigments are dispersed in the ink as long as the effect of the present invention is not impaired. May be.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular-weight dispersant and high-molecular-weight dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant and the like can be used depending on the pigment.
As the dispersant, RT-100 (nonionic surfactant) manufactured by Takemoto Oil & Fat Co., Ltd. and a naphthalene sulfonic acid Na formalin condensate can also be suitably used as the dispersant.
The dispersant may be used alone or in combination of two or more.

<Pigment dispersion>
It is possible to obtain an ink by mixing a material such as water or an organic solvent with a pigment. It is also possible to produce an ink by mixing a material such as water or an organic solvent with a pigment dispersion obtained by mixing a pigment and other water or a dispersant.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. It is good to use a disperser for dispersion.
The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency is 20 nm or more in terms of the maximum number because the dispersion stability of the pigment is good and the image quality such as ejection stability and image density is also high. It is preferably 500 nm or less, and more preferably 20 nm or more and 150 nm or less. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose, but is 0.1% by mass from the viewpoint of obtaining good ejection stability and increasing the image density. 50% by mass or more is preferable, and 0.1% by mass or more and 30% by mass or less is more preferable.
It is preferable to degas the pigment dispersion by filtering the coarse particles with a filter, a centrifuge, or the like, if necessary.

<Additives>
If necessary, a surfactant, an antifoaming agent, an antiseptic / antifungal agent, a rust preventive agent, a pH adjuster and the like may be added to the ink.

<Physical characteristics of ink>
In this embodiment, a coating layer is formed on the support, the surface roughness Ra is 30 nm or more and 35 nm or less, and the transfer of pure water to the recording medium at a contact time of 100 ms measured by a dynamic scanning liquid absorbent meter. Adhesion amount to a recording medium having an amount of 2 ml / m ² or more and 35 ml / m ² or less and a transfer amount of pure water to the recording medium of 3 ml / m ² or more and 40 ml / m ² or less at a contact time of 400 ms. When a solid image is formed by applying ink so that the amount is 500 mg / A4 or more and 700 mg / A4 or less and then heating at 100 ° C. for 2 minutes, the surface roughness Ra of the solid image becomes 15 nm or more and 25 nm or less. It is preferably ink. By using the above copolymer in combination with the water-soluble polyester resin, the change in the dispersed state of the pigment in the image portion is suppressed even if the image portion is heated, and as a result, the surface roughness Ra of the solid image becomes large. Is suppressed. Then, by suppressing the increase in the surface roughness Ra, the decrease in the image density is suppressed.

Here, in the present embodiment, the measured values of the surface roughness Ra of the solid image and the surface roughness Ra of the recording medium are defined as the values measured by using an AFM (atomic force microscope). The size of the visual field when quantifying the surface roughness Ra is 1 μm square. Techniques / devices such as optical microscopes, confocal microscopes, and AFMs are often used to measure surface roughness Ra, but when AFM is used to measure surface roughness Ra in a 1 μm square field of view, surface roughness Ra is measured. The highest correlation with image density is obtained. The AFM measurement at this time is preferably performed in the tapping mode. There is a problem that the image surface is destroyed when the measurement is performed in the contact mode. Further, since the measurement is performed in the air, the measurement may be performed in the non-contact mode, but since the resolution at the atomic image level is not required, the measurement in the non-contact mode is not particularly necessary.

Further, in the present embodiment, a coating layer is formed on the support, the surface roughness Ra is 30 nm or more and 35 nm or less, and the pure water is recorded on the recording medium having a contact time of 100 ms as measured by a dynamic scanning liquid absorbent meter. The transfer amount of pure water to the recording medium at a contact time of 400 ms is 3 ml / m ² or more and 40 ml / m ² or less, and the transfer amount is 2 ml / m ² or more and 35 ml / m ² or less. A solid image was formed by applying ink so that the adhesion amount was 500 mg / A4 or more and 700 mg / A4 or less, and then heating at 100 ° C. for 2 minutes, and the solid image was measured by a variable angle photometer. With ink whose half-value width (half-value full width) σ of the peak created by fitting the peak near 45-degree normal reflection with the normal distribution function of the following equation (1) is 2.0 or more and 2.4 or less. It is preferable to have. By using the above copolymer in combination with the water-soluble polyester resin, the change in the dispersed state of the pigment in the image portion is suppressed even if the image portion is heated, and as a result, the half-value width σ of the solid image may be increased. It is suppressed. In a solid image with a small full width at half maximum σ, the dispersed state of the pigment does not change from a uniform state to a non-uniform state even when the image portion is heated, in other words, diffuse reflection occurs as the surface roughness increases. Indicates that it is not. And, it is suppressed that the image density of such an image becomes low.

A coating layer is formed on the support, the surface roughness Ra is 30 nm or more and 35 nm or less, and the amount of pure water transferred to the recording medium at a contact time of 100 ms measured by a dynamic scanning liquid absorbent meter is 2 ml. The amount of adhesion is 500 mg / m for a recording medium having a / m ² or more and 35 ml / m ² or less and a transfer amount of pure water to the recording medium of 3 ml / m ² or more and 40 ml / m ² or less at a contact time of 400 ms. When a solid image is formed by applying ink so as to be A4 or more and 700 mg / A4 or less and then heating at 100 ° C. for 2 minutes, the surface roughness Ra of the solid image is 15 nm or more and 25 nm or less, and the solid image is solid. The value of the half-value width σ of the peak created by fitting the peak near the 45-degree normal reflection obtained by measuring with a variable-angle photometer with the normal distribution function of the following equation (1) is 2.0 or more. In order to be 2.4 or less, it must be the ink of this embodiment.

<< Recording medium >>
The recording medium can be used without particular limitation, and plain paper, glossy paper, special paper, cloth and the like can be used, but it is also referred to as a low permeability recording medium or a low absorption substrate. ) Can be used particularly preferably.
The low-permeability base material means a base material having a surface having a low water permeability, absorbency, or adsorptivity, and includes a material having a large number of cavities inside but not opening to the outside. Examples of the low-permeability base material include coated paper used for commercial printing, recording media such as paperboard in which used paper pulp is blended in the middle layer and the back layer and the surface is coated.

<Low permeability base material>
As the low-permeability substrate, for example, a recording medium such as coated paper having a support and a surface layer provided on at least one surface side of the support, and further having another layer as needed. Can be mentioned.

In a recording medium having a support and a surface layer, the amount of pure water transferred to the recording medium at a contact time of 100 ms measured by a dynamic scanning liquid absorbent is preferably 2 mL / m ² or more and 35 mL / m ² or less, preferably 2 mL. More preferably, it is / m ² or more and 10 mL / m ² or less.

If the transfer amount of ink and pure water at a contact time of 100 ms is too small, beading may easily occur, and if it is too large, the ink dot diameter after image formation may be too small than the desired diameter. be.

The amount of pure water transferred to the recording medium at a contact time of 400 ms measured by a dynamic scanning liquid absorbent is preferably 3 mL / m ² or more and 40 mL / m ² or less, and more preferably 3 mL / m ² or more and 10 mL / m ² or less. preferable.

If the amount of transfer at a contact time of 400 ms is small, the drying property may be insufficient, and if it is too large, the gloss of the image portion after drying may be easily lowered. The amount of pure water transferred to the recording medium at contact times of 100 ms and 400 ms can be measured on the surface of the recording medium on the side having the surface layer.

Here, the dynamic scanning absorptometer (DSA, Paper Technology Cooperative Magazine, Vol. 48, May 1994, pp. 88-92, Shigenori Kukan) has a liquid absorption amount in an extremely short time. It is a device that can accurately measure. The dynamic scanning liquid absorber reads the speed of the liquid directly from the movement of the meniscus in the capillary, makes the sample disk-shaped, and scans the liquid-absorbing head spirally on it, and scans the speed according to a preset pattern. The measurement is automated by a method of automatically changing and measuring as many points as necessary with one sample.

The liquid supply head to the paper sample is connected to the capillary via a Teflon® tube, and the position of the meniscus in the capillary is automatically read by an optical sensor. Specifically, a dynamic scanning liquid absorption meter (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.) can be used to measure the transfer amount of pure water or ink.

The transfer amount at the contact time of 100 ms and the contact time of 400 ms can be obtained by interpolation from the measured values of the transfer amounts at the contact times in the vicinity of each contact time.

-Support-
The support is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include paper mainly composed of wood fibers and sheet-like substances such as non-woven fabric mainly composed of wood fibers and synthetic fibers.
The thickness of the support is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50 μm to 300 μm. The basis weight of the support is preferably 45 g / m ² to 290 g / m ² .

-Surface layer-
The surface layer contains a pigment, a binder (binder), and, if necessary, a surfactant and other components.
As the pigment, an inorganic pigment or a combination of an inorganic pigment and an organic pigment can be used. Examples of the inorganic pigments include kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, amorphous silica, titanium white, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and water. Examples include zinc oxide and chlorite. The amount of the inorganic pigment added is preferably 50 parts by mass or more with respect to 100 parts by mass of the binder.
Examples of the organic pigment include water-soluble dispersions such as styrene-acrylic copolymer particles, styrene-butadiene copolymer particles, polystyrene particles, and polyethylene particles. The amount of the organic pigment added is preferably 2 parts by mass to 20 parts by mass with respect to 100 parts by mass of the total pigment in the surface layer.
As the binder, it is preferable to use an aqueous resin. As the water-based resin, at least one of a water-soluble resin and a water-dispersible resin can be preferably used. The water-soluble resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyvinyl alcohol, cation-modified polyvinyl alcohol, acetal-modified polyvinyl alcohol, polyester, polyurethane, polyester and polyurethane.
The surfactant contained in the surface layer as needed is not particularly limited and may be appropriately selected depending on the intended purpose. Both can be used.
The method for forming the surface layer is not particularly limited and may be appropriately selected depending on the intended purpose, and can be performed by impregnating or applying a liquid constituting the surface layer on the support. The amount of the liquid constituting the surface layer is not particularly limited and can be appropriately selected depending on the intended purpose. The solid content is preferably 0.5 g / m ² to 20 g / m ² and 1 g / m ² to. 15 g / m ² is more preferable.

<Recording device, recording method>
The ink of the present invention can be suitably used for various recording devices by an inkjet recording method, for example, a printer, a facsimile device, a copying device, a printer / fax / copier multifunction device, a three-dimensional modeling device, and the like.
In the present invention, the recording device and the recording method are devices capable of ejecting ink, various processing liquids, and the like to a recording medium, and a method for recording using the device. The recording medium means a medium to which ink and various treatment liquids can adhere even temporarily.
This recording device can include not only a head portion for ejecting ink, but also means related to feeding, transporting, and discharging paper of a recording medium, a pretreatment device, a device called a posttreatment device, and the like. ..
The recording device and the recording method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the printed surface and the back surface of the recording medium. The heating means and the drying means are not particularly limited, but for example, a hot air heater and an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like. In the recording device and recording method of the present embodiment, after the ejection step of ejecting ink from the ejection means for ejecting ink, a heating step using a heating means for heating and drying the ink on the ejected recording medium is performed. Is preferable. When heating, it is preferable to heat the recording medium at a temperature of 100 ° C. or higher.
Further, the recording device and the recording method are not limited to those in which significant images such as characters and figures are visualized by ink. For example, those that form patterns such as geometric patterns and those that form three-dimensional images are also included.
Further, the recording device includes both a serial type device that moves the discharge head and a line type device that does not move the discharge head, unless otherwise specified.
Further, as this recording device, it is possible to use not only a desktop type but also a wide recording device capable of printing on an A0 size recording medium, or, for example, continuous paper wound in a roll shape as a recording medium. A continuous book printer is also included.
An example of the recording device will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanism portion 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink storage section 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is, for example, a package of an aluminum laminated film or the like. It is formed of members. The ink container 411 is housed in, for example, a plastic container case 414. As a result, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided behind the opening when the cover 401c of the main body of the apparatus is opened. A main tank 410 is detachably attached to the cartridge holder 404. As a result, each ink ejection port 413 of the main tank 410 and the ejection head 434 for each color communicate with each other via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 to the recording medium.

The method of using the ink is not limited to the inkjet recording method, and can be widely used. In addition to the inkjet recording method, examples thereof include a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method, and a spray coating method.

<< Use >>
The use of the ink of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose, and can be applied to, for example, printed matter, paints, coating materials, base materials and the like. Further, it can be used not only as an ink to form two-dimensional characters and images, but also as a three-dimensional modeling material for forming a three-dimensional stereoscopic image (three-dimensional model).
As the three-dimensional modeling apparatus for modeling the three-dimensional object, a known one can be used, and is not particularly limited, but for example, an apparatus provided with ink accommodating means, supply means, ejection means, drying means and the like is used. be able to. The three-dimensional model includes a three-dimensional model obtained by overcoating with ink. Further, a molded product obtained by processing a structure in which ink is applied on a base material such as a recording medium is also included. The molded product is, for example, a recorded material or structure formed in a sheet shape or a film shape, which has been subjected to molding processing such as heat stretching or punching. It is suitably used for molding after decorating the surface of electronic devices, meters of cameras, panels of operation parts, and the like.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

<Measurement of weight average molecular weight of copolymer>
It was measured by GPC (Gel Permeation Chromatography) under the following conditions.
・ Equipment: GPC-8020 (manufactured by Tosoh Corporation)
-Column: TSK G2000HXL and G4000HXL (manufactured by Tosoh Corporation)
・ Temperature: 40 ℃
-Solvent: THF (tetrahydrofuran)
-Flow flow rate: 1.0 mL / min Inject 1 mL of a polymer with a concentration of 0.5% by mass, and use a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample from the molecular weight distribution of the polymer measured under the above conditions. The number average molecular weight Mn and the weight average molecular weight Mw of the copolymer were calculated.

<Example 1>
(Synthesis of copolymer)
62.0 g (525 mmol) of 1,6-hexanediol (manufactured by Tokyo Kasei Co., Ltd.) was dissolved in 700 mL of methylene chloride, and 20.7 g (262 mmol) of pyridine was added. A solution prepared by dissolving 50.0 g (262 mmol) of 2-naphthalenecarbonyl chloride (manufactured by Tokyo Kasei Co., Ltd.) in 100 mL of methylene chloride was added dropwise to this solution with stirring over 2 hours, and then the mixture was stirred at room temperature for 6 hours. .. After washing the obtained reaction solution with water, the organic phase was isolated, dried over magnesium sulfate, and the solvent was distilled off. The residue was purified by silica gel column chromatography using a mixed solvent of methylene chloride / methanol (volume ratio 98/2) as an eluent to obtain 52.5 g of 2-naphthoic acid-2-hydroxyhexyl ester.
Next, 42.1 g (155 mmol) of 2-naphthoic acid-2-hydroxyethyl ester was dissolved in 80 mL of dry methyl ethyl ketone and heated to 60 ° C. A solution of 24.0 g (155 mmol) of 2-methacryloyloxyethyl isocyanate (Kalens MOI, manufactured by Showa Denko KK) dissolved in 20 mL of dry methyl ethyl ketone was added dropwise to this solution with stirring over 1 hour, and then at 70 ° C. Was stirred for 12 hours. After cooling to room temperature, the solvent was distilled off. The residue was purified by silica gel column chromatography using a mixed solvent of methylene chloride / methanol (volume ratio 99/1) as an eluent, and 57.0 g of the following monomer having a structure represented by the following structural formula (1). ) Was obtained.

Next, 1.20 g (16.7 mmol) of acrylic acid (manufactured by Aldrich) and 4.45 g (10.4 mmol) of the above monomer (1) were dissolved in 40 mL of dry methyl ethyl ketone to prepare a monomer solution (above). The molar ratio of the monomer (1) to acrylic acid is "1: 1.6"). A solution in which 0.273 g (1.67 mmol) of 2,2'-azoiso (butyronitrile) (manufactured by Tokyo Kasei Co., Ltd.) was dissolved in the remaining monomer solution after heating 10% of the monomer solution to 75 ° C. under an argon air flow. Was added dropwise over 1.5 hours, and the mixture was stirred at 75 ° C. for 6 hours. After cooling to room temperature, the obtained reaction solution was dropped into hexane. The precipitated copolymer was separated by filtration and dried under reduced pressure to obtain 8.13 g of the copolymer (1) (weight average molecular weight (Mw): 19400, number average molecular weight (Mn): 8200).

Next, the obtained 2.00 g of the copolymer (1) was dissolved in a tetraethylammonium hydroxide aqueous solution so that the concentration of the copolymer was 2.38% by mass and the pH was 8.0. An aqueous solution of the copolymer (1) was prepared.

(Adjustment of pigment dispersion)
Next, 16.0 g of carbon black (NIPEX150, manufactured by Degussa) was added to an aqueous solution of 84.0 g of the copolymer (1), and the mixture was stirred for 12 hours. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. It was filtered through a membrane filter of .2 μm, and the prepared amount of ion-exchanged water was added to obtain 95.0 g of the pigment dispersion (1) (pigment solid content in the pigment dispersion: 16% by mass).

(Ink adjustment)
The following formulation mixture was stirred for 1 hour and then filtered through a membrane filter having a pore size of 1.2 μm to obtain ink (1).
Pigment dispersion (1): 37.5% by mass (pigment solid content in ink: 6.0% by mass, copolymer amount in ink: 0.75% by mass)
-Water-soluble polyester (Tg: -20 ° C, plus coat Z-3310, manufactured by Goo Chemical Co., Ltd.): 0.5% by mass (solid content)
-2-Ethyl-1,3-hexanediol: 2.0% by mass
・ Propylene glycol ・ ・ ・ 41.0% by mass
-Surfactant (DSN-403N, manufactured by Daikin Industries, Ltd.): 1.0% by mass
・ High pure water ・ ・ ・ Remaining amount

<Example 2>
Ink (2) was produced in the same manner as in Example 1 except that the water-soluble polyester was changed from "Plus Coat Z-3310" to the following "Plus Coat Z-880" in the preparation of the ink of Example 1.
-Water-soluble polyester (Tg: 20 ° C, plus coat Z-880, manufactured by Goo Chemical Co., Ltd.)

<Example 3>
In the same manner as in Example 1 except that the content of the water-soluble polyester "Plus Coat Z-3310" was changed from "0.5% by mass" to "1.2% by mass" in the preparation of the ink of Example 1. Ink (3) was produced.

<Example 4>
In the same manner as in Example 1 except that the content of the water-soluble polyester "Plus Coat Z-880" was changed from "0.5% by mass" to "1.2% by mass" in the preparation of the ink of Example 2. Ink (4) was prepared.

<Example 5>
In the same manner as in Example 1 except that the content of the water-soluble polyester "Plus Coat Z-3310" was changed from "0.5% by mass" to "0.1% by mass" in the preparation of the ink of Example 1. Ink (5) was produced.

<Example 6>
In the same manner as in Example 1 except that the content of the water-soluble polyester "Plus Coat Z-3310" was changed from "0.5% by mass" to "2.0% by mass" in the preparation of the ink of Example 1. Ink (6) was prepared.

<Example 7>
Ink (7) was produced in the same manner as in Example 1 except that the water-soluble polyester was changed from "Plus Coat Z-3310" to the following "Plus Coat Z-446" in the preparation of the ink of Example 1.
-Water-soluble polyester (Tg: 47 ° C, plus coat Z-446, manufactured by Goo Chemical Co., Ltd.)

<Example 8>
(Synthesis of copolymer)
In the synthesis of the copolymer of Example 1, the same as in Example 1 except that the molar ratio of the monomer (1) to acrylic acid "1: 1.6" was changed to "1: 0.5". A copolymer (2) (weight average molecular weight (Mw): 19100, number average molecular weight (Mn): 7100) was obtained. Next, an aqueous solution of the copolymer (2) was prepared in the same manner as in Example 1 except that the "copolymer (2)" was used instead of the "copolymer (1)".

(Adjustment of pigment dispersion)
Next, in the preparation of the pigment dispersion of Example 1, the pigment was used in the same manner as in Example 1 except that the "aqueous solution of the copolymer (2)" was used instead of the "aqueous solution of the copolymer (1)". The dispersion (2) (pigment solid content in the pigment dispersion: 16% by mass) was obtained.

(Ink adjustment)
In the preparation of the ink of Example 1, the ink (8) was obtained in the same manner as in Example 1 except that the “pigment dispersion (2)” was used instead of the “pigment dispersion (1)”.

<Example 9>
Ink (9) was produced in the same manner as in Example 1 except that the water-soluble polyester was changed from "Plus Coat Z-3310" to the following "Plus Coat Z-880" in the preparation of the ink of Example 8.

<Example 10>
In the same manner as in Example 8 except that the content of the water-soluble polyester "Plus Coat Z-3310" was changed from "0.5% by mass" to "1.2% by mass" in the preparation of the ink of Example 8. Ink (10) was produced.

<Example 11>
In the same manner as in Example 9 except that the content of the water-soluble polyester "Plus Coat Z-880" was changed from "0.5% by mass" to "1.2% by mass" in the preparation of the ink of Example 9. Ink (11) was produced.

<Comparative Example 1>
(Ink adjustment)
The following formulation mixture was stirred for 1 hour and then filtered through a membrane filter having a pore size of 1.2 μm to obtain ink (12).
Pigment dispersion (1): 37.5% by mass (pigment solid content in ink: 6.0% by mass, copolymer amount in ink: 0.75% by mass)
-Acrylic resin particles (Boncoat 40-418EF, manufactured by DIC Corporation): 3.5% by mass (solid content)
-2-Ethyl-1,3-hexanediol: 2.0% by mass
・ Propylene glycol ・ ・ ・ 41.0% by mass
-Surfactant (DSN-403N, manufactured by Daikin Industries, Ltd.): 1.0% by mass
・ High pure water ・ ・ ・ Remaining amount

<Comparative Example 2>
An ink (13) was produced in the same manner as in Comparative Example 1 except that the resin particles were changed from "acrylic resin particles" to the following "urethane resin particles" in the preparation of the ink of Comparative Example 1.
-Urethane resin particles (Permarin UA-368T, manufactured by Goo Chemical Co., Ltd.)

<Comparative Example 3>
(Synthesis of copolymer)
In a reaction vessel equipped with a gas introduction tube, a thermometer, and a reflux condenser, 182 g of N, N-dimethylformamide (DMF, manufactured by Kanto Chemical Co., Inc.) was placed in an argon atmosphere and heated to 75 ° C. There, 223 g of an aqueous solution prepared by dissolving 30 g of acrylic acid (manufactured by Aldrich) in 193 g of water, 24 g of benzyl acrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and N- [3- (dimethylamino) propyl] acrylamide (manufactured by Tokyo Kasei Kogyo Co., Ltd.). (Abbreviated as DMAPAA) (hereinafter abbreviated as DMAPAA) 212 g of DMF solution in which 6 g was dissolved in 182 g of DMF and 5.4 g of 2,2'-azobisisobutyronitrile (manufactured by Tokyo Kasei Kogyo Co., Ltd./hereinafter abbreviated as AIBN) in 182 g. 187.4 g of the DMF solution dissolved in DMF was added every 30 minutes in 12 divided doses. After adding all of the mixture, stirring was continued at 75 ° C. for 4 hours, and then the mixture was cooled to stop the polymerization to obtain the copolymer (3).

Next, the obtained 2.00 g of the copolymer (3) was dissolved in a tetraethylammonium hydroxide aqueous solution so that the concentration of the copolymer was 2.38% by mass and the pH was 8.0. An aqueous solution of the copolymer (3) was prepared.

(Adjustment of pigment dispersion)
Next, in the preparation of the pigment dispersion of Example 1, the pigment was used in the same manner as in Example 1 except that the "aqueous solution of the copolymer (3)" was used instead of the "aqueous solution of the copolymer (1)". A dispersion (3) (pigment solid content in the pigment dispersion: 16% by mass) was obtained.

(Ink adjustment)
The following formulation mixture was stirred for 1 hour and then filtered through a membrane filter having a pore size of 1.2 μm to obtain ink (14).
Pigment dispersion (3): 37.5% by mass (pigment solid content in ink: 6.0% by mass, copolymer amount in ink: 0.75% by mass)
-Acrylic resin particles (Boncoat 40-418EF, manufactured by DIC Corporation): 3.5% by mass (solid content)
-2-Ethyl-1,3-hexanediol: 2.0% by mass
・ Propylene glycol ・ ・ ・ 41.0% by mass
-Surfactant (DSN-403N, manufactured by Daikin Industries, Ltd.): 1.0% by mass
・ High pure water ・ ・ ・ Remaining amount

<Comparative Example 4>
In the adjustment of the ink of Comparative Example 3, the acrylic resin particles "Boncoat 40-418EF" were changed to the water-soluble polyester "Pluscoat Z-3310", and the content of the water-soluble polyester "Pluscoat Z-3310" was 0.5% by mass. Ink (15) was produced in the same manner as in Comparative Example 3 except that the ink (15) was prepared in the same manner as in Comparative Example 3.

The formulations of the inks (1) to (15) of Examples 1 to 11 and Comparative Examples 1 to 4 are shown in Table 1 below. The unit of the content in each formulation in Table 1 is "mass%".

Next, the inks produced in Examples 1 to 11 and Comparative Examples 1 to 4 and the characteristics of images formed using these inks were evaluated according to the following methods and evaluation criteria. The results are shown in Table 2.

[Image density]
A chart with the general symbols of 64point characters JIS X 0208 (1997), 2223 prepared by filling an inkjet printer (IPSiO GX5000 manufactured by Ricoh Co., Ltd.) with ink produced by Microsoft Word2000 (manufactured by Microsoft). Printing was performed on offset coated paper (Lumi Art Gloss) at 23 ° C. and a 50% RH environment. After printing, the printed matter is immediately put into a constant temperature bath set at 100 ° C. for 2 minutes to heat it, and then the general symbol part of JIS X 0208 (1997), 2223 on the printed surface is X-Rite 938 (X-Rite Co., Ltd.). The color was measured by (manufactured by) and evaluated according to the following evaluation criteria. When the evaluation was B or higher, it was judged to be a practical case.
For the printing mode of the inkjet printer, the driver attached to the printer was used to change the "glossy paper-standard clean" mode to "no color correction" from the user settings of plain paper. The amount of adhesion during printing was adjusted to 500 to 700 mg / A4.
-Evaluation criteria-
A: 2.20 or more B: 2.05 or more and less than 2.20 C: 1.85 or more and less than 2.05 D: less than 1.85

[Surface roughness Ra]
A printed matter was prepared in the same manner as the printed matter used in the above image density measurement. Next, the image portion of the created printed matter was measured by AFM, and the surface roughness Ra when observed in a 1 μm square field of view was calculated. The AFM measurement conditions were as follows.
When the surface roughness of the offset coated paper (Lumi Art Gloss) was measured under the same measurement conditions, the surface roughness Ra was 30 nm or more and 35 nm or less. The amount of pure water transferred to the offset coated paper (Lumi Art Gloss) at a contact time of 100 ms measured by a dynamic scanning liquid absorber is 2 ml / m ² or more and 35 ml / m ² or less, and pure water at a contact time of 400 ms. The amount of transfer to offset coated paper (Lumi Art Gloss) was 3 ml / m ² or more and 40 ml / m ² or less.
-Measurement condition-
-Device: Bruker Dimension Icon
-Measurement mode: Tapping mode-Cantilever: Olympus AC240TS (resonance frequency 70 kHz, spring constant 2 N / m)
・ Scan Rate: 1Hz
-Samples / Line: 256
・ Lines: 256
-Amplitude Setpoint: 250mV
・ Tilt correction: Primary

[Measurement of variable angle photometer]
A printed matter was prepared in the same manner as the printed matter used in the above image density measurement. Next, the image portion of the created printed matter was measured by a three-dimensional variable angle spectrophotometric measurement system GCMS-11 (manufactured by Murakami Color Technology Laboratory). The measurement conditions were as follows.
-Measurement condition-
-Light source: D50 / 2deg
・ Incident angle: 45 deg
・ Light receiving angle: -75 to 5 deg
-Evaluation wavelength: 550 nm
・ Evaluation physical properties: Reflectance

When the measurement is performed under the above conditions, a peak derived from specular reflection appears in the -45 deg part due to the gloss of the image part. Therefore, the peak shape is fitted by the normal distribution function (Equation 1), and the half width σ is calculated. I asked.

粘度の測定には、粘度計（ＲＥ８０Ｌ、東機産業株式会社製）を使用し、２５℃における粘度を、５０回転で測定した。
－評価基準－
Ａ：粘度の変化率が±５％以内
Ｂ：粘度の変化率が±５％を超え、±８％以内
Ｃ：粘度の変化率が±８％を超え、±１０％以内
Ｄ：粘度の変化率が±１０％を超える [Preservation]
Each ink was filled in an ink container and stored at 70 ° C. for one week, and the rate of change in viscosity after storage with respect to the viscosity before storage was calculated from the following formula and evaluated according to the following criteria. In addition, B or more is practical.

A viscometer (RE80L, manufactured by Toki Sangyo Co., Ltd.) was used to measure the viscosity, and the viscosity at 25 ° C. was measured at 50 rpm.
-Evaluation criteria-
A: Viscosity change rate within ± 5% B: Viscosity change rate exceeds ± 5% and within ± 8% C: Viscosity change rate exceeds ± 8% and within ± 10% D: Viscosity change Rate exceeds ± 10%

[Fixability]
A printed matter was prepared in the same manner as the printed matter used in the above image density measurement. Next, the unprinted offset coated paper (Lumi Art Gloss) was brought into contact with the image portion of the created printed matter and rubbed 20 times. Next, the degree of transfer stains on the unprinted offset coated paper was visually observed and evaluated according to the following criteria. In addition, B or more is practical.
-Evaluation criteria-
A: Transfer stains are not visually observed B: Transfer stains are slightly observed visually C: Transfer stains are clearly observed visually

400 Image forming device 401 Image forming device exterior 401c Device body cover 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For each color of black (K), cyan (C), magenta (M), yellow (Y) Main tank 411 Ink storage unit 413 Ink discharge port 414 Storage container case 420 Mechanical unit 434 Discharge head 436 Supply tube

Japanese Unexamined Patent Publication No. 2017-88706 Japanese Unexamined Patent Publication No. 2006-342323

Claims (15)

Contains water, pigments, copolymers, water-soluble polyesters,
The copolymer is an ink having a structural unit represented by any one of the following general formulas (1) to (3) and a structural unit having an anionic functional group.

(In the above general formula (1), R ¹ represents a hydrogen atom or a methyl group, and A ₁ , A ₂ , and A ₃ are independently -O-, -CO-O-, and -O-CO-, respectively. Represents a divalent substituent selected from the group of -CO-NH-, -NH-CO-, -NH-CO-O-, -O-CO-NH-, and X ₁ and X ₂ are independent of each other. An alkylene group having 1 to 12 carbon atoms, an alkenylene group having 1 to 12 carbon atoms, and a divalent substituent selected from the group of the general formula (4), the general formula (5), and the general formula (6). Ar represents a naphthyl group .)

(In the above general formula (2), R ¹ , A ₁ , A ₂ , X ₁ , X ₂ , and Ar each independently represent the same as the general formula (1).)

(In the above general formula (3), R ¹ , A ₁ , A ₂ , A ₃ , X ₁ , X ₂ , and Ar each independently represent the same as the general formula (1), and A ₄ is -O. -, -CO-O-, -O-CO-, -CO-NH-, -NH-CO-, -NH-CO-O-, -O-CO-NH-divalent substitution selected from the group Represents a group, where Z represents a divalent hydrocarbon group.)

(In the above general formula (4), l represents an integer of 1 or more and 10 or less.)

(In the above general formula (5), m represents an integer of 1 or more and 10 or less.)

(In the above general formula (6), n represents an integer of 1 or more and 10 or less.) The ink according to claim 1 , wherein the structural unit represented by the general formula (1) has a structural unit represented by the following general formula (7).

(In the above general formula (7), R ² represents a hydrogen atom or a methyl group, and L represents an alkylene group having 2 or more carbon atoms and 12 or less carbon atoms.) The ink according to claim 1 or 2 , wherein the structural unit having an anionic functional group has a structural unit represented by the following general formula (8).

(In the above general formula (8), R ³ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom or a cation.) The ink according to any one of claims 1 to 3 , wherein the content of the water-soluble polyester is 0.5% by mass or more and 1.2% by mass or less with respect to the total amount of the ink. The ink according to any one of claims 1 to 4 , wherein the Tg of the water-soluble polyester is −20 ° C. or higher and 20 ° C. or lower. The ink according to any one of claims 1 to 5 , wherein the pigment is carbon black. The ink according to any one of claims 1 to 6 , which does not substantially contain resin particles. The mass ratio of the content of the water-soluble polyester to the content of the copolymer (water-soluble polyester / copolymer) is 0.13 or more and 2.67 or less according to any one of claims 1 to 7 . The listed ink. A coating layer is formed on the support, the surface roughness Ra is 30 nm or more and 35 nm or less, and the amount of pure water transferred to the recording medium at a contact time of 100 ms measured by a dynamic scanning liquid absorbent meter is 2 ml / m. The amount of adhesion to the recording medium of ² or more and 35 ml / m ² or less and the transfer amount of pure water to the recording medium at a contact time of 400 ms is 3 ml / m ² or more and 40 ml / m ² or less is 500 mg / A4 or more. Claim 1 in which the surface roughness Ra of the solid image is 15 nm or more and 25 nm or less when a solid image is formed by applying the ink so as to be 700 mg / A4 or less and then heating at 100 ° C. for 2 minutes. The ink according to any one of 8 to 8 . A coating layer is formed on the support, the surface roughness Ra is 30 nm or more and 35 nm or less, and the amount of pure water transferred to the recording medium at a contact time of 100 ms measured by a dynamic scanning liquid absorbent meter is 2 ml / m. The amount of adhesion to the recording medium of ² or more and 35 ml / m ² or less and the transfer amount of pure water to the recording medium at a contact time of 400 ms is 3 ml / m ² or more and 40 ml / m ² or less is 500 mg / A4 or more. A solid image is formed by applying the ink so as to be 700 mg / A4 or less and then heating at 100 ° C. for 2 minutes.
The value of the half width σ of the peak created by fitting the peak near the 45-degree specular reflection obtained by measuring the solid image with a variable-angle photometer using the normal distribution function of the following equation (1) is 2. The ink according to any one of claims 1 to 9 , which is 0.0 or more and 2.4 or less.

An ink container for containing the ink according to any one of claims 1 to 10 . A recording device comprising the ink container according to claim 11 , a ejection means for ejecting the contained ink, and a heating means for heating the ejected ink at 100 ° C. or higher. The ink container according to claim 11 and a ejection means for ejecting the contained ink to a recording medium.
In the recording medium, a coating layer is formed on the support, the surface roughness Ra is 30 nm or more and 35 nm or less, and the transfer of pure water to the recording medium at a contact time of 100 ms measured by a dynamic scanning liquid absorbent meter. A recording device having an amount of 2 ml / m ² or more and 35 ml / m ² or less, and a transfer amount of pure water to the recording medium at a contact time of 400 ms of 3 ml / m ² or more and 40 ml / m ² or less. The ink container according to claim 11 , a ejection means for ejecting the contained ink to a recording medium, and a heating means for heating the ejected ink at 100 ° C. or higher.
In the recording medium, a coating layer is formed on the support, the surface roughness Ra is 30 nm or more and 35 nm or less, and the transfer of pure water to the recording medium at a contact time of 100 ms measured by a dynamic scanning liquid absorbent meter. A recording device having an amount of 2 ml / m ² or more and 35 ml / m ² or less, and a transfer amount of pure water to the recording medium at a contact time of 400 ms of 3 ml / m ² or more and 40 ml / m ² or less. A recording method comprising a ejection step of ejecting the ink according to any one of claims 1 to 10 .

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