JP6683053B2 - Ink and manufacturing method thereof, ink container, image forming method, image forming apparatus, and image formed article - Google Patents

Description

  The present invention relates to an ink and a method for manufacturing the same, an ink container, an image forming method, an image forming apparatus, and an image formed product.

  The inkjet recording method is popular because it has the advantage that the process is simpler than other recording methods, full color can be easily achieved, and an image having a high resolution can be obtained even with a device having a simple configuration. It is expanding from personal to office applications, commercial printing and industrial printing. In such an ink jet recording method, a water-based ink composition using a water-soluble dye as a coloring material is mainly used, but has a drawback that it has poor water resistance and light resistance. Pigment inks using the above pigments are being developed.

  In inkjet printing for office use, plain paper is mainly used as a recording medium, and high image density is required. Generally, when a pigment ink is printed on plain paper, the pigment penetrates into the paper without remaining on the paper surface, so that the pigment density on the paper surface is reduced and the image density is reduced. Increasing the pigment concentration in the ink increases the image density, but increases the viscosity of the ink and decreases the ejection stability.

  Further, in the fields of commercial printing and industrial printing, there is a need for a technique capable of stably producing an image with higher resolution and higher definition at a higher speed. As the recording medium, plain paper, coated paper, art paper, non-permeable film such as PET film and the like are used, and high compatibility of ink with the recording medium is required. In the ink jet recording method, in order to prevent paper curl that occurs when printing on plain paper, or when printing on coated paper or art paper, increase ink permeability, speed up drying, and reduce beading. In order to prevent this, there is a method of adding a hydrophilic organic solvent to the water-based ink.

  Further, the water-based pigment ink used in the inkjet recording system or the writing instrument, unlike the water-based dye ink prepared by dissolving the dye in water, needs to stably disperse the water-insoluble pigment in the water for a long period of time. , Various pigment dispersants have been developed. For example, a graft polymer having an aromatic ring in its side chain has been proposed (see, for example, Patent Document 1).

  It is an object of the present invention to provide an ink having a high storage stability and high image density even when an image is formed on plain paper.

The ink of the present invention as a means for solving the above problems is water, a coloring material, and an ink containing a copolymer,
The copolymer contains a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2).
However, in said general formula (1), R < ₁ > represents a hydrogen atom or a methyl group, a represents the integer of 6-10, b represents the integer of 0 or 1.
However, In the general formula (2), _{R 2} and _{R 3} represents a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.

  According to the present invention, it is possible to provide an ink having a high storage stability and a high image density even when recorded on plain paper.

FIG. 1 is a perspective explanatory view showing an example of an inkjet recording apparatus. FIG. 2 is a perspective explanatory view showing an example of a main tank in the inkjet recording apparatus.

(ink)
The ink of the present invention contains water, a colorant, and a copolymer containing a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), an organic solvent, And at least one of the surfactants, and further contains other components as necessary.
The ink of the present invention is based on the finding that long-term storage stability is insufficient when a conventional graft polymer is used as a pigment dispersant.

<Copolymer>
The copolymer contains a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and further contains other structural units as necessary.
However, in said general formula (1), R < ₁ > represents a hydrogen atom or a methyl group, a represents the integer of 6-10, b represents the integer of 0 or 1.
When a is an integer of 6 to 10, a naphthyl group is present at a position distant from the polymer main chain, so that high image density can be obtained even when an image is formed on plain paper, and storage stability is high. Ink is obtained.
When the value of a is less than 6, a naphthyl group is present at a position close to the polymer main chain, so that the storage stability of the ink and the image density may be insufficient.
When the value of a exceeds 10, the viscosity of the ink tends to increase, and the storage stability of the ink may become insufficient.

In the general formula (2), _{R 2} and _{R 3} represents a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.
In the general formula (2), n and m represent the average number of moles of ethylene oxide (C ₂ H ₄ O) and propylene oxide (C ₃ H ₆ O) added, and n is an integer of 1 to 90. , M represents an integer of 0 to 90, and from the viewpoint of ink storage stability and image density, n is preferably 4 to 50, m is preferably 0, n is 8 to 30, and m is 0. More preferable.

  The structural unit represented by the general formula (2) is not particularly limited and may be appropriately selected depending on the purpose, but is preferably the structural unit represented by the following general formula (3).

However, in the general formula (3), R ₂ and R ₃ represent a hydrogen atom or a methyl group, and n represents an integer of 1 to 90.

  In the structural unit represented by the general formula (1), a naphthyl group having one end at an end through an alkyl chain in an open end (open end, that is, a pendant structure portion) is a coloring material in the ink. Due to the π-π stacking with the pigment that is

As can be understood from the description of the above-mentioned “naphthyl group which is present at the terminal via the alkyl chain in the pendant structure part”, the structural unit represented by the general formula (1) typically has an alkyl group. It may be the main chain of the copolymer with pendant structures such as pendant terminal naphthyl groups. However, of course, the case where a part is contained in the side chain is not excluded.
For example, it is a well known fact that it is difficult to completely eliminate the secondary radical polymerization reaction that produces a branched structure.
Further, when preparing the pigment dispersion in which the pigment is dispersed in water, when the copolymer used in the present invention is used, since a naphthyl group is present at the terminal of the side chain of the copolymer, the pigment surface is Since it is easily adsorbed and has a high adsorption power with respect to the pigment, a pigment dispersion having high dispersibility and stable for a long time can be obtained.
The presence of a naphthyl group at a position distant from the main chain of the copolymer makes it difficult for the other components to be copolymerized to inhibit pigment adsorption.

  Specific examples of the structural unit represented by the general formula (1) are shown below, but the invention is not limited to the following specific examples.

  The content of the structural unit represented by the general formula (1) is appropriately selected depending on the intended purpose without any limitation, but it is 30% by mass or more and 80% by mass with respect to the total amount of the copolymer. % Or less, preferably 40% by mass or more and 70% by mass or less. When the content is within the preferable range, it is advantageous in that the image density and the storage stability are good when used in the ink.

  The structural unit represented by the general formula (2) and the cellulose mainly constituting the plain paper are hydrophilic. Therefore, it is considered that the structural unit represented by the general formula (2) has an affinity for cellulose rather than a hydrophobic solvent. When the copolymer is used in ink, the copolymer adsorbed on the pigment during printing is adsorbed on the cellulose, and the pigment easily stays on the paper surface. In the general formula (2), it is considered that n has a polyethylene glycol chain and a polypropylene glycol chain of 1 to 90 and m of 0 to 90, so that it is easy to contact with cellulose and more easily adsorbed on cellulose. As a result, high image density can be exhibited even on plain paper.

  The content of the structural unit represented by the general formula (2) is not particularly limited and may be appropriately selected depending on the purpose, but is 20% by mass or more and 70% by mass or less with respect to the total amount of the copolymer. The following is preferable, and 30% by mass or more and 60% by mass or less is more preferable. When the content is 20% by mass or more and 70% by mass or less, it is advantageous in that when used in an ink, the image density and the storage stability are good.

The copolymer may have a repeating unit derived from another polymerizable monomer, in addition to the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2).
The other polymerizable monomer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a polymerizable hydrophobic monomer, a polymerizable hydrophilic monomer, and a polymerizable surfactant. . Among these, it is preferable that no ionic monomer is contained among the polymerizable hydrophilic monomers. Although the mechanism is not clear, when an ionic monomer is further contained in addition to the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2), the general formula (2) The storage stability of the ink and the image density tend to deteriorate probably due to the interaction between the structural unit represented and the ionic monomer.

  Examples of the polymerizable hydrophobic monomer include unsaturated ethylene monomers having an aromatic ring such as styrene, α-methylstyrene, 4-t-butylstyrene, and 4-chloromethylstyrene; methyl (meth) acrylate; Ethyl (meth) acrylate, -n-butyl (meth) acrylate, dimethyl maleate, dimethyl itaconate, dimethyl fumarate, dodecyl (meth) acrylate (C12), tridecyl (meth) acrylate (C13), ( Tetradecyl (meth) acrylate (C14), pentadecyl (meth) acrylate (C15), hexadecyl (meth) acrylate (C16), heptadecyl (meth) acrylate (C17), nonadecyl (meth) acrylate (C19), ( Eicosyl acrylate (C20), henicosyl acrylate ( 21), alkyl (meth) acrylate such as docosyl (meth) acrylate (C22); 1-heptene, 3,3-dimethyl-1-pentene, 4,4-dimethyl-1-pentene, 3-methyl-1. -Hexene, 4-methyl-1-hexene, 5-methyl-1-hexene, 1-octene, 3,3-dimethyl-1-hexene, 3,4-dimethyl-1-hexene, 4,4-dimethyl-1 -Hexene, 1-nonene, 3,5,5-trimethyl-1-hexene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene , 1-octadecene, 1-nonadecene, 1-eicosene, 1-dococene, and the like, and unsaturated ethylene monomers having an alkyl group. These may be used alone or in combination of two or more.

Examples of the polymerizable hydrophilic monomer include 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, N-methylol (meth) acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone. And nonionic unsaturated ethylene monomers such as acrylamide, N, N-dimethylacrylamide, Nt-butylacrylamide, N-octylacrylamide, Nt-octylacrylamide and the like.
The polymerizable hydrophobic monomer and the polymerizable hydrophilic monomer may be used alone or in combination of two or more.
The content of the polymerizable hydrophobic monomer and the polymerizable hydrophilic monomer is the sum of the structural unit represented by the general formula (1) and the monomer containing the structural unit represented by the general formula (2). The amount is preferably 5% by mass or more and 100% by mass or less.

The polymerizable surfactant is an anionic or nonionic surfactant having at least one radically polymerizable unsaturated double bond group in the molecule.
Examples of the anionic surfactant, ammonium sulfate base ^_(-SO 3 - _NH ^{4 +)} hydrocarbon compound having a sulfate group and an allyl group _{(-CH 2} -CH = CH 2), such as, ammonium sulfate base (-SO ₃ ^- NH ₄ ⁺⁾ sulfate group and methacrylic group, such as _{[-CO-C (CH 3) =} CH 2 ] a hydrocarbon compound having, or ammonium sulfate base ^_(-SO 3 - _NH ^{4 +)} sulfate, such as base and 1 - an aromatic hydrocarbon compound having a propenyl group (-CH = _CH 2 _{CH 3)} and the like.
As the anionic surfactant, a commercially available product can be used, and as the commercially available product, for example, Elyominol JS-20, RS-300 manufactured by Sanyo Kasei Co., Ltd .; Aqualon manufactured by Daiichi Kogyo Seiyaku Co., Ltd. KH-10, Aqualon KH-1025, Aqualon KH-05, Aqualon HS-10, Aqualon HS-1025, Aqualon BC-0515, Aqualon BC-10, Aqualon BC-1025, Aqualon BC-20, Aqualon BC-2020, etc. Can be mentioned.

Examples of the nonionic surface active agent, e.g., a 1-propenyl group (-CH = _CH 2 _{CH 3)} polyoxyethylene group _{[- (C 2 H 4 O)} n-H ] a hydrocarbon compound having a or Examples thereof include aromatic hydrocarbon compounds. Examples of commercially available nonionic surfactants include, for example, Aqualon RN-20, Aqualon RN-2025, Aqualon RN-30, and Aqualon RN-50 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd .; Latem PD manufactured by Kao Corporation. -104, latemuru PD-420, latemuru PD-430, latemuru PD-450, etc. are mentioned.

The polymerizable surfactant may be used alone or in combination of two or more.
The content of the polymerizable surfactant is based on the total amount of the compound forming the structural unit represented by the general formula (1) and the compound forming the structural unit represented by the general formula (2). Therefore, it is preferably 0.1% by mass or more and 10% by mass or less.

The weight average molecular weight of the copolymer is preferably 5,000 or more and 50,000 or less, more preferably 15,000 or more and 40,000 or less in terms of polystyrene. When the weight average molecular weight is in the range of 5,000 or more and 50,000 or less, it is advantageous in that when used in an ink, image density and storage stability are good.
The weight average molecular weight of the copolymer can be measured by, for example, GPC (Gel Permeation Chromatography) method.

The structure of the copolymer can be analyzed by using a general analysis method such as NMR or IR.
The molar ratio of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) constituting the copolymer is the molar ratio of the compound used in synthesizing the copolymer. It can be determined by the ratio. Further, it can be determined by NMR from the copolymer.

<Method for synthesizing copolymer>
The copolymer containing the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) in the present invention is a compound represented by the following general formula (4) and the following general formula (4): It is preferably synthesized by radical polymerization from a polymerizable material (starting material) containing the compound represented by formula (5).
In the general formula (4), _{R 4} represents a hydrogen atom or a methyl group, a represents an integer of 6 to 10, b represents an integer of 0 or 1.
In the general formula (5), _{R 5} and _{R 6} represent a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.

  Specific examples of the compound represented by the general formula (4) will be given below, but the present invention is not limited to the following specific examples.

The compound represented by the general formula (4) can be synthesized as follows.
That is, as shown in the following reaction formula (1), first, a diol compound (R-1) and a naphthalene derivative (R-2) having a carboxyl group are reacted in the presence of an acid catalyst to give a reaction intermediate (R -3) is obtained.

[Reaction formula 1]

  As another method, as shown in the following reaction formula (2), an acid chloride (R-4) of a naphthalene derivative having a carboxyl group and a diol compound (R-1) are replaced with amine or pyridine. The reaction intermediate (R-3) can also be obtained by reacting in the presence of an acid acceptor.

[Reaction formula 2]

  Then, as shown in the following reaction formula (3), (meth) acrylic acid chloride (R-5) is reacted with the (R-3) to give the compound (2a) represented by the general formula (4). ) Can be obtained.

[Reaction formula 3]
However, in the reaction formulas (1) to (3), R ₁ , a, and b have the same meaning as in the general formula (1).

  As the compound represented by the general formula (5), those synthesized appropriately may be used, or commercially available products may be used. Examples of the commercially available product include Bremmer PE-90, PE-200, PE-350, AE-90U, AE-200, AE-400, PME-100, PME-200, PME-400, PME-1000, PME. -4000, AME-200, AME-400, 70PEP-350B (all are NOF Corporation make) etc. are mentioned.

As a method for synthesizing the copolymer, a method using a radical polymerization initiator is preferable, and a solution polymerization method in which a polymerization reaction is carried out in a solution is more preferable, because the polymerization operation and the adjustment of the molecular weight are easy.
The solvent for radical polymerization in the solution polymerization method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethyl acetate and acetic acid. Acetic acid ester solvents such as butyl; aromatic hydrocarbon solvents such as benzene, toluene, xylene; isopropanol, ethanol, cyclohexane, tetrahydrofuran, dimethylformamide, dimethylsulfoxide, hexamethylphosphoamide and the like. These may be used alone or in combination of two or more. Among these, ketone solvents, acetic acid ester solvents, and alcohol solvents are preferable.

  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 and peroxy ester. , Cyano-based azobisisobutyronitrile, azobis (2-methylbutyronitrile), azobis (2,2'-isovaleronitrile), non-cyano-based dimethyl-2,2'-azobisisobutyrate, etc. Is mentioned. These may be used alone or in combination of two or more. Among these, organic peroxides and azo compounds are preferable, and azo compounds are more preferable, since the molecular weight is easily controlled and the decomposition temperature is low.

  The content of the radical polymerization initiator is appropriately selected depending on the intended purpose without any limitation, but it is preferably 1% by mass or more and 10% by mass or less based on the total amount of the polymerizable monomers.

An appropriate amount of a chain transfer agent may be added to adjust the molecular weight of the copolymer.
Examples of the chain transfer agent include mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, dodecylmercaptan, 1-dodecanethiol, and thioglycerol.
The polymerization temperature is appropriately selected depending on the intended purpose without any limitation, but it is preferably 50 ° C or higher and 150 ° C or lower, more preferably 60 ° C or higher and 100 ° C or lower. The polymerization time is appropriately selected depending on the intended purpose without any limitation, but it is preferably 3 hours or more and 48 hours or less.

The copolymer used in the present invention is not particularly limited and can be appropriately selected depending on the purpose, and can be used as a pigment dispersant or an additive to ink. When used as a dispersant for the pigment, further improvement in storage stability in ink containing a large amount of organic solvent is recognized.
When the copolymer is used as a pigment dispersant, the content of the copolymer is not particularly limited and can be appropriately selected depending on the purpose, but with respect to 100 parts by mass of the pigment, The amount is preferably 1 part by mass or more and 100 parts by mass or less, more preferably 5 parts by mass or more and 80 parts by mass or less. When the content is 1 part by mass or more and 100 parts by mass or less, it is advantageous in that the image density and the storage stability are good. In addition, other pigment dispersants may be used in combination as long as the effect of the copolymer as a pigment dispersant is not impaired.

  When the copolymer is used as an additive for the ink, the content of the copolymer is not particularly limited and can be appropriately selected according to the purpose, but is 0 based on the total amount of the ink. The content is preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 5% by mass or less. When the content is 0.05% by mass or more, the effect of improving dispersibility and storability is recognized, and when the content is 10% by mass or less, a viscosity range suitable for ejecting the ink from the recording head can be obtained. Becomes

<Water>
As the water, for example, deionized water, ultrafiltered water, reverse osmosis water, pure water such as distilled water, or ultrapure water can be used.
The content of the water in the ink is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 10% by mass or more and 90% by mass or less from the viewpoint of ink drying property and ejection reliability. 20 mass% or more and 60 mass% or less are more preferable.

<Color material>
As the color material, a pigment or a dye can be used. Pigments are preferable in terms of adsorption ability of the above-mentioned copolymer to a coloring material, because pigments are superior to dyes, and water resistance and light resistance.

  The pigment is appropriately selected depending on the intended purpose without any limitation, and examples thereof include black or color inorganic pigments and organic pigments. These may be used alone or in combination of two or more.

Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and a known method such as a contact method, a furnace method, and a thermal method. The carbon black prepared can be used.
Examples of black pigments include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, and metals such as copper and iron (CI pigment black 11). , Metal oxides such as titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1).
The carbon black is a carbon black produced by a furnace method or a channel method and has a primary particle diameter of 15 nm or more and 40 nm or less, a specific surface area by the BET method of 50 m ² / g or more and 300 m ² / g or less, and a DBP oil absorption of 40 mL. / 100 g or more and 150 mL / 100 g or less, those having a volatile content of 0.5% or more and 10% or less, and a pH of 2 or more and 9 or less are preferable.

Examples of the organic pigments include azo pigments (including, for example, azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone). Pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofuraron pigments, etc., dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. it can.
Of these pigments, those having a good affinity for water are particularly preferably used.

Examples of the azo pigment include azo lake, insoluble azo pigment, condensed azo pigment, chelate azo pigment, and the like.
Examples of the polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofuraron pigments, and rhodamine B lake pigments. .
Examples of the dye chelates include basic dye chelates and acid dye chelates.

  The yellow pigment is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 73, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 75, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 98, C.I. I. Pigment Yellow 114, C.I. I. Pigment Yellow 120, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 129, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 174, C.I. I. Pigment Yellow 180 and the like.

  The magenta pigment is not particularly limited and may be appropriately selected depending on the intended purpose. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 112, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 146, C.I. I. Pigment Red 168, C.I. I. Pigment red 176, C.I. I. Pigment Red 184, C.I. I. Pigment Red 185, C.I. I. Pigment Red 202, Pigment Violet 19, and the like.

  The cyan pigment is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4, C.I. I. Pigment Blue 15:34, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 60, C.I. I. Pigment Blue 63, C.I. I. Pigment Blue 66; C.I. I. Bat Blue 4, C.I. I. Bat blue 60 and the like can be mentioned.

  As a yellow pigment, C.I. I. Pigment Yellow 74 and C.I. as a magenta pigment. I. Pigment Red 122, C.I. I. Pigment Violet 19 and cyan pigments such as C.I. I. By using Pigment Blue 15: 3, a well-balanced ink having excellent color tone and light resistance can be obtained.

The coloring material newly manufactured for the present invention can also be used for the ink of the present invention.
Further, from the viewpoint of color developability of the obtained image, a self-dispersion pigment may be used, and an anionic self-dispersion pigment is preferable. The anionic self-dispersion pigment refers to a pigment that is dispersion-stabilized by introducing an anionic functional group into the pigment surface directly or through another atomic group.
As the pigment before dispersion stabilization, various conventionally known pigments such as those listed in WO 2009/014242 can be used.
The anionic functional group means a functional group capable of dissociating more than half of hydrogen ions at pH 7.0. Examples of the anionic functional group include a carboxyl group, a sulfo group, a phosphonic acid group and the like. Among these, a carboxyl group or a phosphonic acid group is preferable from the viewpoint of increasing the optical density of the obtained image.
Examples of the method of introducing an anionic functional group onto the surface of the pigment include a method of oxidizing carbon black.
As a method of oxidizing the carbon black, for example, a method of treating the carbon black with hypochlorite, ozone water, hydrogen peroxide, chlorite, nitric acid or the like, Patent No. 3808504 gazette, Japanese Patent Publication No. 2009- 515007 and Japanese Patent Publication No. 2009-506196, surface treatment methods using a diazonium salt can be mentioned.
Examples of commercially available pigments having a hydrophilic functional group introduced on the surface include CW-1, CW-2, CW-3 (above, manufactured by Orient Chemical Industry Co., Ltd.); CAB-O-JET200, CAB-. O-JET300, CAB-O-JET400 (manufactured by Cabot Corporation) and the like can be mentioned.

  The content of the pigment in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.5% by mass or more and 20% by mass or less, and 1% by mass or more and 10% by mass or less. More preferable.

As the dye, a dye classified into an acid dye, a direct dye, a basic dye, a reactive dye, and an edible dye in the color index can be used.
Examples of the acid dye and the food dye include C.I. I. Acid Black 1, 2, 7, 24, 26, 94, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Blue 9, 29, 45, 92, 249, C.I. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289, C.I. I. Food Black 1, 2, C.I. I. Food Yellow 3, 4, C.I. I. Hood Red 7, 9, 14 and the like can be mentioned.
Examples of the direct dye include C.I. I. Direct Black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, (168), 171, C.I. I. Direct Yellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142, 144, C.I. I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202, C.I. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227, C.I. I. Direct Orange 26, 29, 62, 102 and the like can be mentioned.
Examples of the basic dye include C.I. I. Basic Black 2, 8, C.I. I. Basic Yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 64, 65, 67, 70, 73, 77, 87, 91, C.I. I. Basic Blue 1, 3, 5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93, 105, 117, 120, 122, 124, 129, 137, 141, 147, 155, C.I. I. Basic Red 2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70, 73, 78, 82, 102, 104, 109, 112 and the like.
Examples of the reactive dye include C.I. I. Reactive Black 3, 4, 7, 11, 12, 17, C.I. I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67, C.I. I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95, C.I. I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97 and the like.

  The ink of the present invention is an organic solvent in order to enhance the permeability to plain paper, coated paper, etc., to further suppress the occurrence of beading, and to prevent the ink from drying by utilizing the wetting effect. It is preferable to contain

<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 polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include, for example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 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- Polyhydric alcohols such as sundiol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol and petriol, ethylene glycol mono Polyhydric alcohol alkyl ethers such as ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monophenyl ether, ethylene glycol monoethyl ether Polyhydric alcohol aryl ethers such as benzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl- -Pyrrolidone, 1,3-dimethyl-2-imidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam, γ-butyrolactone, formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, Amides such as N-dimethylpropionamide and 3-butoxy-N, N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol, propylene carbonate, Examples include ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or less because it not only functions as a wetting agent but also obtains good drying properties.

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 glycol ether compounds 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; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

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

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

  The ink of the present invention preferably contains a surfactant in order to enhance the penetrability and wettability of plain paper, coated paper and the like, and further suppress the occurrence of beading.

-Surfactant-
As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone surfactant is not particularly limited and can be appropriately selected according to the purpose. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-chain both-end modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound having a polyalkylene oxide structure introduced into the side chain of the Si moiety of dimethylsiloxane.
Examples of the fluorinated surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphoric acid ester compound, a perfluoroalkyl ethylene oxide adduct and a perfluoroalkyl ether group in the side chain. A polyoxyalkylene ether polymer compound is particularly preferable because it has a low foaming property. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salts. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in its side chain include a sulfuric acid ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in its side chain and a perfluoroalkyl ether group in its side chain. Examples thereof include salts of polyoxyalkylene ether polymers. As counter ions of the salt in these fluorine-based surfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) are used. _{3 and the} like.
Examples of the amphoteric surfactant include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of the nonionic surfactant include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan. Examples thereof include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and salt of polyoxyethylene alkyl ether sulfate. These may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-modified polydimethylsiloxane. Examples thereof include polydimethyl siloxane modified at both chain ends, and a polyether modified silicone surfactant having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group shows good properties as an aqueous surfactant. preferable.
As such a surfactant, those synthesized appropriately may be used, or commercially available products may be used. Commercially available products can be obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Kagaku Co., Ltd.
The polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the general formula (S-1) may be dimethylpolyethylene. Examples thereof include those introduced into the side chain of the Si portion of siloxane.
[General formula (S-1)]
(However, in the general formula (S-1), m, n, a, and b represent integers.
R and R'represent an alkyl group and an alkylene group. )
As the above polyether-modified silicone-based surfactant, commercially available products can be used, for example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-. 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Big Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), etc. are mentioned.

As the fluorine-based surfactant, a fluorine-substituted compound having 2 to 16 carbon atoms is preferable, and a fluorine-substituted compound having 4 to 16 carbon atoms is more preferable.
Examples of the fluorine-based surfactant include a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain.
Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable because it has a low foaming property, and is particularly preferably a fluorine-based compound represented by the general formula (F-1) or the general formula (F-2). Surfactants are preferred.
[General Formula (F-1)]
In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10 and n is preferably an integer of 0 to 40 in order to impart water solubility.
[General Formula (F-2)]
_{C n F 2n + 1- CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y
In the compound represented by the general formula (F-2), Y is H, or CnF _{2n + 1} and n is an integer of 1 to 6, or CH ₂ CH (OH) CH ₂ -CnF _{2n + 1} and n is 4 to 6. An integer, or CpH _{2p + 1} and p is an integer of 1 to 19. a is an integer of 4 to 14.
A commercially available product may be used as the above-mentioned fluorine-based surfactant.
Examples of this commercially available product include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F -1405, F-474 (all manufactured by DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont) ); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), po Fox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by OMNOVA), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) and the like, among these, good printing quality , FS-300 manufactured by DuPont, FT-110, FT-250, FT-251, FT- manufactured by Neos Co., Ltd., in particular, in that the color developability, the penetrability to paper, the wettability, and the leveling property are remarkably improved. 400S, FT-150, FT-400SW, Polyfox PF-151N manufactured by Omnova Co., Ltd. and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferable.

  The content of the surfactant in the ink is appropriately selected depending on the intended purpose without any limitation, but it is 0.001 mass% from the viewpoint of excellent wettability and ejection stability and improving image quality. % Or more and 5 mass% or less is preferable, and 0.05 mass% or more and 5 mass% or less is more preferable.

  The ink of the present invention preferably contains, as necessary, other components such as an antiseptic / antifungal agent, a rust inhibitor, and a pH adjusting agent.

<Antiseptic and fungicide>
The antiseptic / antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust preventive>
The rust preventive agent is not particularly limited, and examples thereof include acid sulfite and sodium thiosulfate.

<PH adjuster>
The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and may be appropriately selected depending on the purpose. For example, the viscosity, surface tension, pH and the like are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, from the viewpoint that the printing density and character quality are improved, and that good ejection properties can be obtained, and 5 mPa · s or more and 25 mPa · s or less are preferable. More preferable. Here, as the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. The measurement conditions are 25 ° C., standard cone rotor (1 ° 34 ′ × R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN / m or less at 25 ° C., and more preferably 32 mN / m or less at 25 ° C., since the ink is preferably leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12, and more preferably 8 to 11 from the viewpoint of preventing the corrosion of the metal member with which the ink comes into contact.

(Ink manufacturing method)
The method for producing an ink of the present invention is a method for producing an ink containing water, a coloring material, and a copolymer,
The method further comprises a step of synthesizing a copolymer by radically polymerizing a compound represented by the general formula (4) and a polymerizable material containing the compound represented by the general formula (5), and further, if necessary. Including other steps.
The step of synthesizing the copolymer is the same as the method for producing the copolymer.

Examples of the other steps include a mixing step and the like.
The mixing step is a step of dispersing or dissolving the water, the coloring material, the copolymer, and the other components, and stirring and mixing.
The copolymer may be used as a pigment dispersant in producing a pigment dispersion.
The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, ultrasonic dispersion, or the like. The stirring and mixing can be performed with a stirrer using a normal stirring blade, a magnetic stirrer, a high speed disperser, or the like.

<Recording medium>
The recording medium used for recording is not particularly limited, and examples thereof include plain paper, glossy paper, special paper, cloth, film, OHP sheet, and general-purpose printing paper.

(Ink container)
The ink storage container of the present invention is an ink storage container including an ink storage portion that stores ink, and the ink stored in the ink storage portion is the ink of the present invention. The ink is contained in a container, and further has other members appropriately selected as necessary.
The container is not particularly limited, and its shape, structure, size, material and the like can be appropriately selected according to the purpose. For example, at least an ink containing portion formed of an aluminum laminate film, a resin film or the like can be used. Those having it are suitable.

<Recording device, recording method>
The ink of the present invention can be suitably used for various recording apparatuses using an inkjet recording method, such as printers, facsimile machines, copying machines, printer / fax / copier composite machines, and three-dimensional modeling apparatuses.
In the present invention, the recording device and the recording method are a device capable of ejecting ink, various treatment liquids, and the like onto a recording medium, and a method of recording using the device. The recording medium means a medium to which ink or various treatment liquids can be attached even temporarily.
This recording device can include not only a head portion for ejecting ink, but also means for feeding, conveying, and discharging a recording medium, and other devices such as a pre-processing device and a post-processing device. .
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 printing surface or the back surface of the recording medium. The heating means and the drying means are not particularly limited, but, for example, a warm air heater or an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording device and the recording method are not limited to those in which a significant image such as a character or a figure is visualized by ink. For example, the thing which forms patterns, such as a geometric pattern, and the thing which models a three-dimensional image are also included.
Further, the recording apparatus includes both a serial type apparatus that moves the ejection head and a line type apparatus that does not move the ejection head unless otherwise limited.
Furthermore, this recording apparatus can use not only a desktop type but also a wide recording apparatus that can print on an A0 size recording medium, or a continuous paper wound in a roll shape as a recording medium. It also includes a simple continuous printer.
An example of the recording device will be described with reference to FIGS. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective 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 section 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink storage portion 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packed with, for example, an aluminum laminate film. It is formed of a member. The ink container 411 is housed in a container case 414 made of plastics, for example. 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 on the inner side of the opening when the cover 401c of the apparatus body is opened. The main tank 410 is detachably attached to the cartridge holder 404. As a result, the ink discharge ports 413 of the main tank 410 communicate with the ejection heads 434 for each color via the supply tubes 436 for each color, and ink can be ejected from the ejection heads 434 to the recording medium.

  The method of using the ink is not limited to the ink jet recording method and can be widely used. In addition to the inkjet recording method, for example, 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, a spray coating method and the like can be mentioned.

The use of the ink of the present invention is not particularly limited and can be appropriately selected according to the purpose. For example, it can be applied to printed matter, paints, coating materials, bases and the like. Furthermore, it can be used not only as a two-dimensional character or image by using as ink, but also as a three-dimensional modeling material for forming a three-dimensional three-dimensional image (three-dimensional model).
As a three-dimensional modeling device for modeling a three-dimensional molded object, a known device can be used, and is not particularly limited. For example, a device including an ink storage unit, a supply unit, a discharge unit, a drying unit, and the like is used. be able to. The three-dimensional object includes a three-dimensional object obtained by, for example, over-coating ink. Further, a molded product obtained by processing a structure obtained by applying ink on a base material such as a recording medium is also included. The molded product is, for example, a recording product or a structure formed in a sheet shape or a film shape, which is subjected to a molding process such as heat drawing or punching process, and is, for example, an automobile, an OA device, or an electric machine. -Suitable for applications such as electronic devices, meters for cameras, panels for operation parts, etc., after molding the surface after molding.

(Image formation)
The image-formed product of the present invention is an image-formed product having a recording medium and a recording layer on the recording medium, wherein the recording layer contains a coloring material and a copolymer, and if necessary, other Including ingredients.
The copolymer contains a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2).
However, in said general formula (1), R < ₁ > represents a hydrogen atom or a methyl group, a represents the integer of 6-10, b represents the integer of 0 or 1.
However, In the general formula (2), _{R 2} and _{R 3} represents a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.

  The image-formed product has a high image density even when an image is formed on plain paper, and can be suitably used for various purposes as various printed or image-recorded materials.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.
Further, the average molecular weight of the copolymers used in Examples and Comparative Examples was determined as follows.

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

(Monomer Synthesis Example 1)
-Synthesis of Monomer M-1-
62.0 g (525 mmol) of 1,6-hexanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 700 mL of methylene chloride, and 20.7 g (262 mmol) of pyridine was added.
To this solution, a solution of 50.0 g (262 mmol) of 2-naphthalenecarbonyl chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) in 100 mL of methylene chloride was added dropwise with stirring over 2 hours, and then at room temperature (25 ° C). ) And stirred for 6 hours. After the obtained reaction solution was washed 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, and 52.5 g of a reaction intermediate represented by the following structural formula (I-1) Got the body

Next, 41.0 g (151 mmol) of the reaction intermediate represented by the structural formula (I-1) was dissolved in 250 mL of methylene chloride, and 20.0 g (198 mmol) of triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.). Was added. This solution was cooled in an ice bath, 20.0 g (191 mmol) of methacrylic acid chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added dropwise over 30 minutes, and then the mixture was stirred in an ice bath for 1 hour at room temperature (25 ° C). ) And stirred for 3 hours. The precipitate was filtered off, the filtrate was washed with water, saturated aqueous sodium hydrogen carbonate solution and saturated brine, the organic phase was isolated, dried over magnesium sulfate, and the solvent was evaporated. The residue was purified by silica gel column chromatography using n-hexane / ethyl acetate (volume ratio 6/1) mixed solvent as an eluent to give 39.4 g of a monomer M-1 represented by the following structural formula. Obtained.

(Monomer Synthesis Example 2)
-Synthesis of Monomer M-3-
150.0 g (1.26 mol) of 1,6-hexanediol and 50.0 g (0.268 mol) of 1-naphthalene acetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) were placed in a reaction vessel and heated to 70 ° C. with stirring. And allowed to dissolve. 1.30 g of concentrated sulfuric acid was added, and the mixture was stirred at 70 ° C. for 2 hours. After cooling to room temperature (25 ° C.), a solution prepared by dissolving 1.06 g of sodium hydroxide in 600 mL of water was added and washed. 500 mL of ethyl acetate was added, the organic phase was extracted, and then washed with water. The organic phase was isolated, dried over magnesium sulphate and evaporated. The residue was purified by silica gel column chromatography using n-hexane / ethyl acetate (volume ratio 3/2) mixed solvent as an eluent and represented by 61.5 g of the following structural formula (I-2). A reaction intermediate was obtained.

Next, 43.0 g (150 mmol) of the reaction intermediate represented by the structural formula (I-2) was dissolved in 250 mL of methylene chloride, and 20.0 g (198 mmol) of triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.). Was added. This solution was cooled in an ice bath, and 17.4 g (192 mmol) of acrylic acid chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added dropwise over 30 minutes, followed by stirring in an ice bath for 1 hour at room temperature (25 ° C). ) And stirred for 3 hours. The precipitate was filtered off, the filtrate was washed with water, saturated aqueous sodium hydrogen carbonate solution and saturated brine, the organic phase was isolated, dried over magnesium sulfate, and the solvent was evaporated. The residue was purified by silica gel column chromatography using a mixed solvent of n-hexane / ethyl acetate (volume ratio 7/1) as an eluent to obtain 37.6 g of a monomer M-3 represented by the following structural formula. Obtained.

(Monomer Synthesis Example 3)
-Synthesis of Monomer M-6-
64.0 g (367 mmol) of 1,10-decanediol (manufactured by Kanto Chemical Co., Inc.) was dissolved in 900 mL of dry tetrahydrofuran, and 17.4 g (220 mmol) of pyridine was added.
To this solution, a solution of 35.0 g (183 mmol) of 2-naphthalenecarbonyl chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) in 100 mL of methylene chloride was added dropwise with stirring over 2 hours, and then at room temperature (25 ° C). ) And stirred for 12 hours. After adding 500 mL of ethyl acetate and washing 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 n-hexane / ethyl acetate (volume ratio 4/1) mixed solvent as an eluent, and represented by 43.1 g of the following structural formula (I-3). A reaction intermediate was obtained.

Next, 32.8 g (100 mmol) of the reaction intermediate represented by the structural formula (I-3) was dissolved in 400 mL of methylene chloride, and 17.2 g (170 mmol) of triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.). Was added. This solution was cooled in an ice bath, and 15.0 g (144 mmol) of methacrylic acid chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes, followed by stirring in an ice bath for 1 hour at room temperature (25 ° C). ) And stirred for 4 hours. The solvent was distilled off from the reaction solution, dissolved in 300 mL of ethyl acetate, and then washed with water. The organic phase was isolated, dried over magnesium sulphate and evaporated. The residue was purified by silica gel column chromatography using n-hexane / methylene chloride (volume ratio 3/2) mixed solvent as an eluent to obtain 32.1 g of a monomer M-6 represented by the following structural formula. Obtained.

(Synthesis Example 1 of Copolymer)
-Synthesis of Copolymer CP-1-
A monomer solution was prepared by dissolving 50.1 g (147 mmol) of the monomer M-1 and 49.9 g (44.9 mmol) of Bremmer PME-1000 (manufactured by NOF CORPORATION) in 200 mL of dry methyl ethyl ketone. After heating 10% by mass of the monomer solution to 75 ° C. under an argon stream, 3.50 g of 2,2′-azobis (isobutyronitrile) was added to the remaining monomer solution (AIBN, manufactured by Tokyo Chemical Industry Co., Ltd.). , And 0.5 g of a chain transfer agent (α-thioglycerol, manufactured by Tokyo Chemical Industry Co., Ltd.) were 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 filtered off and dried under reduced pressure to obtain 96.8 g of [copolymer CP-1] (weight average molecular weight (Mw): 19,500).
Next, the concentration of the obtained copolymer was adjusted with ion-exchanged water so that the concentration of the copolymer was 10% by mass, to prepare a 10% by mass aqueous solution of the copolymer CP-1.

(Synthesis Examples 2 to 13 of Copolymer)
-Synthesis of Copolymers CP-2 to 13-
In Synthesis Example 1 of the copolymer, a monomer containing the structural unit represented by the general formula (1) and the general formula (2) with the content (parts by mass) shown in Table 1-1 is used, and -2, the content (parts by mass) of the polymerization initiator (AIBN) and, if necessary, a chain transfer agent (α-thioglycerol, manufactured by Tokyo Chemical Industry Co., Ltd.) are used, and the general formula is used as necessary. Except that styrene (manufactured by Tokyo Chemical Industry Co., Ltd.) or dodecyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) is used as a monomer other than the monomer containing the structural unit represented by (1) and the general formula (2). , [Copolymers CP-2 to 13] were obtained in the same manner as in Synthesis Example 1 of Copolymer.
The weight average molecular weight Mw of each of the obtained copolymers CP-2 to 13 is as shown in Table 1-2.
As the monomer containing the structural unit represented by the general formula (2), a blemmer manufactured by NOF CORPORATION is used, and details of the monomer are shown in Table 2.
Next, the concentration of the obtained copolymer was adjusted with ion-exchanged water so that the concentration of the copolymer was 10% by mass, to prepare 10% by mass aqueous solutions of the copolymers CP-2 to 13.

(Preparation Example 1 of pigment dispersion)
-Preparation of Pigment Dispersion PD-1-
With respect to 40.0 parts by mass of a 10% by mass aqueous solution of the copolymer CP-1, 16.0 parts by mass of carbon black (NIPEX150, manufactured by Degussa) and 44.0 parts by mass of pure water were added and stirred for 12 hours. . The obtained mixture was circulated and dispersed for 1 hour at a peripheral speed of 10 m / s using a disk type bead mill (KDL type, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls having a diameter of 0.1 mm) was used, and then the average pore diameter was obtained. The mixture was filtered through a 1.2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain 97.0 parts by mass of [pigment dispersion PD-1] (pigment solid content concentration: 16% by mass).

(Preparation Examples 2 to 18 of pigment dispersion)
-Preparation of Pigment Dispersions PD-2 to 18-
Pigment Dispersions PD-2 to 18 were obtained in the same manner as in Pigment Dispersion Preparation Example 1 except that the pigment dispersion formulation shown in Table 3 was changed.

In Table 3, the following products were used as pigments other than carbon black.
-Pigment Blue 15: 3 (Chromofine Blue A-220JC, manufactured by Dainichiseika Kogyo Co., Ltd.)-Pigment Red 122 (Toner Magenta EO02, manufactured by Clariant)
・ Pigment Yellow 74 (First Yellow 531, manufactured by Dainichiseika Kogyo Co., Ltd.)

(Example 1)
-Preparation of Ink GJ-1-
40.0 parts by mass of pigment dispersion PD-1, 10.0 parts by mass of glycerin, 15.0 parts by mass of 1,3-butanediol, 10.0 parts by mass of 3-methoxy-N, N-dimethylpropione Amide, 10.0 parts by mass of 3-ethyl-3-hydroxymethyloxetane, 1.0 part by mass of 2-ethyl-1,3-hexanediol, 1.0 part by mass of 2,2,4-trimethyl-1. , 3-pentanediol, 1.0 part by mass of Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and 12.0 parts by mass of ion-exchanged water were mixed and stirred for 1 hour, and then with an average pore diameter of 1.2 μm. The ink GJ-1 of Example 1 was produced by filtering with a membrane filter.

(Examples 2 to 18)
-Preparation of Inks GJ-2 to 18-
Inks GJ-2 to 18 of Examples 2 to 18 were prepared in the same manner as in Example 1 except that the ink formulations shown in Table 4-1 and Table 4-2 were changed.

(Comparative Example 1)
<Preparation of Comparative Ink RGJ-1>
-Synthesis of Comparative Copolymer RCP-1-
A monomer solution was prepared by dissolving 8.20 g of methoxypolyethylene glycol methacrylate (n≈23) and 7.03 g of a monomer having a structure represented by the following structural formula (1) in 30 mL of dry methyl ethyl ketone. After heating 10% by mass of the monomer solution to 75 ° C. under an argon stream, a solution in which 0.556 g of 2,2-azobis (isobutyronitrile) was dissolved in the remaining monomer solution was taken for 1.5 hours. And added dropwise, and the mixture was stirred at 75 ° C. for 6 hours. It cooled to room temperature (25 degreeC), and poured the obtained reaction solution into hexane. The precipitated copolymer was filtered off and dried under reduced pressure to obtain 14.11 g of comparative copolymer RCP-1 (weight average molecular weight (Mw): 12,500).

  Next, using this, in the same manner as in Synthesis Example 1 of copolymer, a 10 mass% aqueous solution of comparative copolymer RCP-1 was prepared.

-Preparation of Comparative Pigment Dispersion RPD-1-
Next, a preparation example of a pigment dispersion except that the 10 mass% aqueous solution of the copolymer CP-1 in Preparation Example 1 of the pigment dispersion was used instead of the 10 mass% aqueous solution of the comparative copolymer RCP-1. Comparative pigment dispersion RPD-1 was obtained in the same manner as in 1.

-Preparation of comparative ink RGJ-1-
Next, a comparative ink RGJ-1 was obtained in the same manner as in Example 1 except that the comparative pigment dispersion RPD-1 was used instead of the pigment dispersion PD-1 in the production of the ink of Example 1. .

(Comparative example 2)
-Preparation of comparative ink RGJ-2-
Same as Preparation Example 16 of pigment dispersion except that 10% by mass aqueous solution of comparative copolymer RCP-1 was used instead of 10% by mass aqueous solution of copolymer CP-1 in Preparation Example 16 of pigment dispersion To obtain Comparative Pigment Dispersion RPD-2.
Next, Comparative Ink RGJ-2 was obtained in the same manner as in Example 16 except that Comparative Pigment Dispersion RPD-2 was used in place of Pigment Dispersion PD-16 in the preparation of the ink of Example 16. .

(Comparative Example 3)
-Preparation of comparative ink RGJ-3-
Same as Preparation Example 17 of pigment dispersion except that 10% by mass aqueous solution of copolymer CP-1 in Preparation Example 17 of pigment dispersion was used instead of 10% by mass aqueous solution of comparative copolymer RCP-1 Then, a comparative pigment dispersion RPD-3 was obtained.
Next, Comparative Ink RGJ-3 was obtained in the same manner as in Example 17, except that Comparative Pigment Dispersion RPD-3 was used in place of Pigment Dispersion PD-17 in the preparation of the ink of Example 17. .

(Comparative example 4)
-Preparation of comparative ink RGJ-4-
Same as Preparation Example 18 of pigment dispersion except that 10% by mass aqueous solution of comparative copolymer RCP-1 was used instead of 10% by mass aqueous solution of copolymer CP-1 in Preparation Example 18 of pigment dispersion Thus, a comparative pigment dispersion RPD-4 was obtained.
Next, Comparative Ink RGJ-4 was obtained in the same manner as in Example 18 except that Comparative Pigment Dispersion RPD-4 was used instead of Pigment Dispersion PD-18 in the ink preparation of Example 18.

(Comparative example 5)
<Preparation of Comparative Ink RGJ-5>
-Synthesis of Comparative Copolymer RCP-2-
80 g of 2-phenoxyethyl methacrylate as a monomer, 3.7 g of 3-mercapto-1-propanol as a chain transfer agent, and 0.3 g of 2,2-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator. It was dissolved in 160 mL of tetrahydrofuran (THF), heated to 65 ° C. under a nitrogen atmosphere and reacted for 7 hours. The resulting solution was allowed to cool, 80 mg of dibutyltin dilaurate (IV) and a catalytic amount of hydroquinone were added, and 10.0 g of 2-methacryloyloxyethyl isocyanate was added dropwise. After heating to 50 ° C. and reacting for 2.5 hours, reprecipitation was performed with a mixed solvent of methanol and water for purification, and 71 g of macromonomer MM-1 (weight average molecular weight (Mw): 4,000, The number average molecular weight (Mn): 1,900) was obtained.

  Next, after heating 20 g of methyl ethyl ketone to 75 ° C. under a nitrogen atmosphere, 1.16 g of dimethyl-2,2′-azobisisobutyrate, 9 g of the macromonomer MM-1, 1. A solution prepared by dissolving 8 g of p-styrenesulfonic acid and 49.2 g of methyl methacrylate in 40 g of methyl ethyl ketone was added dropwise over 3 hours. After completion of the dropping, the reaction was continued for another 1 hour, and then a solution of 0.2 g of dimethyl-2,2'-azobisisobutyrate dissolved in 0.6 g of methyl ethyl ketone was added, and the temperature was raised to 80 ° C and heated for 4 hours. It was stirred. Further, a solution prepared by dissolving 0.2 g of dimethyl-2,2'-azobisisobutyrate in 0.6 g of methyl ethyl ketone was added, and the mixture was heated and stirred for 6 hours. After cooling, the obtained reaction solution was dropped into hexane, and the precipitated graft polymer was separated by filtration and dried to obtain a comparative copolymer RCP-2 (weight average molecular weight (Mw): 22,000). .

-Preparation of Pigment Dispersion RPD-5-
Next, Preparation Example 1 of Pigment Dispersion except that a 10 mass% aqueous solution of Comparative Copolymer RCP-2 was used instead of the 10 mass% aqueous solution of Copolymer CP-1 in Preparation Example 1 of Pigment Dispersion Comparative pigment dispersion RPD-5 was obtained in the same manner as described above.

-Preparation of comparative ink RGJ-5-
Next, Comparative Ink RGJ-5 was obtained in the same manner as in Example 1 except that Comparative Pigment Dispersion RPD-5 was used in place of Pigment Dispersion PD-1 in the production of the ink of Example 1. .

(Comparative example 6)
<Preparation of Comparative Ink RGJ-6>
-Synthesis of Copolymer RCP-3-
72.0 g (500 mmol) of 2-naphthol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 125.0 g (1,000 mmol) of ethylene glycol mono-2-chloroethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to 500 mL. It was dissolved in N-methyl-2-pyrrolidinone (manufactured by Kanto Chemical Co., Inc.) and stirred at room temperature (25 ° C) for 1 hour. Furthermore, it stirred at 110 degreeC for 10 hours. After cooling to room temperature, 2,500 mL of pure water was added to the obtained reaction solution, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered off and dried under reduced pressure.
70.0 g of the solid obtained by the above reaction, 45.0 g (450 mmol) of triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 250 mL of tetrahydrofuran, and the mixture was stirred in an ice bath for 30 minutes. 36.6 g (350 mmol) of methacryloyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was slowly added dropwise thereto, and the mixture was further stirred in an ice bath for 3 hours. To the obtained solution, 250 mL of ethyl acetate and 100 mL of pure water were added and washed with water. Next, the ethyl acetate layer was isolated and washed with a saturated saline solution. The ethyl acetate layer was isolated, dried over magnesium sulfate, and the solvent was evaporated. The residue was purified by silica gel column chromatography to obtain 80.5 g of the monomer of the following structural formula (2).

  Next, 12.0 g of methyl ethyl ketone was added to a 100 mL three-necked flask equipped with a stirrer and a cooling tube, and heated to 72 ° C. under an argon stream. Here, 2.4 g (8.00 mmol) of the monomer represented by the structural formula (2), 1.2 g (13.9 mol) of methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 7.8 g (44.3 mmol). ) Benzyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.6 g (0.54 mmol) of Bremmer PME-1000 (manufactured by NOF CORPORATION), and 0.14 g (0.61 mmol) of 2,2′-. A solution of dimethyl azobis (isobutyrate) (manufactured by Wako Pure Chemical Industries, Ltd.) in 6.0 g of methyl ethyl ketone was added dropwise over 3 hours. After completion of the dropwise addition, the mixture was further reacted for 1 hour, and a solution prepared by dissolving 0.06 g (0.26 mmol) of dimethyl 2,2′-azobis (isobutyrate) in 2.0 g of methyl ethyl ketone was added and heated to 78 ° C. Stir for hours. After that, reprecipitation was repeated twice with hexane to purify the copolymer. After the purification treatment, the copolymer was filtered off and dried under reduced pressure to obtain 11.5 g of a comparative copolymer RCP-3 (weight average molecular weight (Mw): 31,800).

-Preparation of Pigment Dispersion RPD-6-
4.0 parts by mass of the comparative copolymer RCP-3 was added to 1.9 parts by mass of a 35% by mass tetraethylammonium hydroxide aqueous solution (manufactured by Tokyo Chemical Industry Co., Ltd.) and 50.0 parts by mass of 3-methoxy-N. , N′-dimethylpropionamide, and 28.1 parts by mass of ion-exchanged water.
To 84.0 parts by mass of an aqueous solution of the comparative copolymer RCP-3, 16.0 parts by mass of carbon black (NIPEX150, manufactured by Degussa) was added and stirred for 12 hours. The obtained mixture was circulated and dispersed for 1 hour at a peripheral speed of 10 m / s using a disk type bead mill (KDL type, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls having a diameter of 0.1 mm) was used, and then the average pore diameter was obtained. The mixture was filtered through a 1.2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain 95.0 parts by mass of pigment dispersion RPD-6 (pigment solid content concentration: 16% by mass).

-Preparation of comparative ink RGJ-6-
40.0 parts by weight of the pigment dispersion RPD-6, 10.0 parts by weight of 1,3-butanediol, 10.0 parts by weight of glycerin, 1.0 part by weight of 2-ethyl-1,3-hexane. Diol, 1.0 part by mass of 2,2,4-trimethyl-1,3-pentanediol, 1.0 part by mass of Unidyne DSN-403N (manufactured by Daikin Industries, Ltd., solid content 100% by mass), and 37. After mixing 0 part by mass of ion-exchanged water and stirring for 1 hour, the mixture was filtered through a membrane filter having an average pore size of 1.2 μm to obtain comparative ink RGJ-6.

(Comparative Example 7)
<Preparation of Comparative Ink RGJ-7>
-Synthesis of Comparative Copolymer RCP-4-
32.5 g (525 mmol) of ethylene glycol (manufactured by Wako Pure Chemical Industries, 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 Kogyo Co., Ltd.) in 100 mL of methylene chloride was added dropwise to this solution while stirring over 2 hours, and then at room temperature (25 ° C). ) And stirred for 6 hours. After the obtained reaction solution was washed 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 97/3) as an eluent to obtain 39.6 g of a reaction intermediate represented by the following structural formula (3). Obtained.

Next, 32.4 g (150 mmol) of the reaction intermediate represented by the structural formula (3) was dissolved in 250 mL of methylene chloride, and 20.0 g (198 mmol) of triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was added. It was This solution was cooled in an ice bath, 20.0 g (191 mmol) of methacrylic acid chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added dropwise over 30 minutes, and then the mixture was stirred in an ice bath for 1 hour at room temperature (25 ° C). ) And stirred for 3 hours. The precipitate was filtered off, the filtrate was washed with water, saturated aqueous sodium hydrogen carbonate solution and saturated brine, the organic phase was isolated, dried over magnesium sulfate, and the solvent was evaporated. The residue was purified by silica gel column chromatography using n-hexane / ethyl acetate (volume ratio 5/1) mixed solvent as an eluent to obtain 31.1 g of a monomer represented by the following structural formula (4). Obtained.

  55.6 g (196 mmol) of the monomer represented by the structural formula (4) and 44.4 g (39.9 mmol) of Bremmer PME-1000 (manufactured by NOF CORPORATION) were dissolved in 200 mL of dry methyl ethyl ketone to prepare the monomer. A solution was prepared. After heating 10% by mass of the monomer solution to 75 ° C. under an argon stream, 4.00 g of 2,2′-azobis (isobutyronitrile) was added to the remaining monomer solution (AIBN, manufactured by Tokyo Chemical Industry Co., Ltd.). Was added dropwise over 1.5 hours, and the mixture was stirred at 75 ° C. for 6 hours. After cooling to room temperature (25 ° C.), the obtained reaction solution was poured into hexane. The precipitated copolymer was separated by filtration and dried under reduced pressure to obtain 97.2 g of comparative copolymer RCP-4 (weight average molecular weight (Mw): 18,200).

  Then, using this, in the same manner as in Synthesis Example 1 of the copolymer, a 10 mass% aqueous solution of the comparative copolymer RCP-4 was prepared.

-Preparation of Comparative Pigment Dispersion RPD-7-
Next, a preparation example of the pigment dispersion except that the 10 mass% aqueous solution of the copolymer CP-1 in Preparation Example 1 of the pigment dispersion was used instead of the 10 mass% aqueous solution of the comparative copolymer RCP-4. Comparative Pigment Dispersion RPD-7 was obtained in the same manner as in 1.

-Preparation of comparative ink RGJ-7-
Next, Comparative Ink RGJ-7 was obtained in the same manner as in Example 1 except that Comparative Pigment Dispersion RPD-7 was used in place of Pigment Dispersion PD-1 in the preparation of the ink of Example 1. .

  Next, various properties of the manufactured pigment dispersions and inks of Examples 1 to 18 and Comparative Examples 1 to 7 were evaluated as follows. The results are shown in Table 5.

<Storage stability of pigment dispersion>
Each pigment dispersion was filled in a glass container having a volume of 30 mL in an amount of 15 mL and stored at 70 ° C. for 2 weeks. The rate of change in viscosity after storage with respect to the viscosity before storage was obtained from the following mathematical formula, and evaluated according to the following criteria. In addition, C 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 rotations.
[Evaluation criteria]
A: Viscosity change rate within ± 5% B: Viscosity change rate over ± 5%, within ± 8% C: Viscosity change rate over ± 8%, within ± 10% D: Viscosity change The rate exceeds ± 10% and within ± 30% E: The rate of change in viscosity exceeds ± 30% (cannot be evaluated due to gelation)

<Ink storage stability>
Each ink was filled in an ink container and stored at 70 ° C. for 1 week. The rate of change in viscosity after storage with respect to the viscosity before storage was obtained from the following mathematical formula, and evaluated according to the following criteria. In addition, C 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 rotations.
[Evaluation criteria]
A: Viscosity change rate within ± 5% B: Viscosity change rate over ± 5%, within ± 8% C: Viscosity change rate over ± 8%, within ± 10% D: Viscosity change The rate exceeds ± 10% and within ± 30% E: The rate of change in viscosity exceeds ± 30% (cannot be evaluated due to gelation)

<Image density>
Inkjet printer (IPSiO GX5000, manufactured by Ricoh Co., Ltd.) was filled with each ink under an environment of 23 ° C. and 50% RH, and 64 points of JIS X 0208 (1997), 2223 general made by Microsoft Word 2000 (manufactured by Microsoft) were used. A chart with symbols is stamped on plain paper 1 (XEROX4200, manufactured by XEROX) and plain paper 2 (MyPaper, manufactured by Ricoh Co., Ltd.), and the symbol portion on the printed surface is marked with X-Rite 938 (X-Rite Co., Ltd.). (Manufactured) and color was evaluated according to the following criteria. In addition, C or more is practical.
As the print mode, a mode in which the "plain paper-standard fast" mode was changed to "no color correction" from the user setting for plain paper using a driver attached to the printer was used.
The general symbols of JIS X 0208 (1997) and 2223 are symbols whose outer shape is a square and whose entire surface is filled with ink.
[Evaluation criteria]
A: 1.25 or more B: 1.20 or more and less than 1.25 C: 1.10 or more and less than 1.20 D: less than 1.10 E: Pigment cannot be dispersed because it gels and cannot be printed in the ink

From the results of Table 6, the pigment dispersions prepared by using the copolymers having naphthyl groups at the ends of the side chains of Examples 1 to 18 are the copolymers having no naphthyl groups at the ends of the side chains of Comparative Examples 1 to 5. It had excellent storage stability and image density as compared with the pigment dispersion prepared by using the polymer. It is considered that this is because the naphthyl group of the copolymer and the π-π interaction between the pigment increased the adsorptivity to the pigment.
In addition, as in Comparative Example 6, even if it has a naphthyl group at the terminal of the side chain, depending on the selection of other monomers used for the synthesis of the copolymer, the storage stability of the ink and the image density are low, It turns out that it is difficult to obtain practical quality.
In addition, as in Comparative Example 7, when it has a naphthyl group at the end of the side chain and also contains the structural unit represented by the general formula (2), the naphthyl group is located near the polymer main chain. When it was present, the storage stability of the ink and the image density were insufficient. This is presumed to be because if a naphthyl group is present at a position close to the polymer main chain, the copolymerized hydrophilic group is forced to be present near the naphthyl group, and pigment adsorption of the naphthyl group is inhibited. It

Aspects of the present invention are, for example, as follows.
<1> An ink containing water, a coloring material, and a copolymer,
The ink is characterized in that the copolymer contains a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2).
However, in said general formula (1), R < ₁ > represents a hydrogen atom or a methyl group, a represents the integer of 6-10, b represents the integer of 0 or 1.
However, In the general formula (2), _{R 2} and _{R 3} represents a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.
<2> The ink according to <1>, wherein the structural unit represented by the general formula (2) is a structural unit represented by the following general formula (3).
However, in the general formula (3), R ₂ and R ₃ represent a hydrogen atom or a methyl group, and n represents an integer of 1 to 90.
<3> The ink according to any one of <1> to <2>, wherein the structural unit represented by the general formula (1) is one represented by the following structural formula.
<4> The ink according to any one of <1> to <3>, wherein n is 4 to 50 and m is 0 in the general formula (2).
<5> The ink according to any one of <1> to <4>, wherein n is 8 to 30 and m is 0 in the general formula (2).
<6> The ink according to any one of <1> to <5>, wherein the content of the structural unit represented by the general formula (1) in the copolymer is 40% by mass or more and 70% by mass or less. Is.
<7> The ink according to any one of <1> to <6>, wherein the copolymer has a weight average molecular weight of 15,000 or more and 40,000 or less.
<8> The ink according to any one of <1> to <7>, wherein the content of the copolymer is 0.05% by mass or more and 10% by mass or less.
<9> The ink according to any one of <1> to <8>, wherein the color material is a pigment.
<10> The ink according to any one of <1> to <9>, further containing at least one of an organic solvent and a surfactant.
<11> A method for producing an ink containing water, a coloring material, and a copolymer,
An ink including a step of synthesizing a copolymer by radically polymerizing a compound represented by the following general formula (4) and a polymerizable material containing a compound represented by the following general formula (5). Is a manufacturing method.
In the general formula (4), _{R 4} represents a hydrogen atom or a methyl group, a represents an integer of 6 to 10, b represents an integer of 0 or 1.
In the general formula (5), _{R 5} and _{R 6} represent a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.
<12> An ink storage container including an ink storage portion that stores ink, wherein the ink stored in the ink storage portion is the ink according to any one of <1> to <10>. A characteristic ink container.
<13> An image forming method comprising: an ink flying step of applying a stimulus to the ink according to any one of <1> to <10> to fly the ink to form an image.
<14> The image forming method according to <13>, wherein the stimulus is at least one selected from heat, pressure, vibration, and light.
<15> An image forming apparatus comprising: an ink flying unit that applies a stimulus to the ink according to any one of <1> to <10> to fly the ink to form an image.
<16> The image forming apparatus according to <15>, wherein the stimulus is at least one selected from heat, pressure, vibration, and light.
<17> An image formed product having a recording medium and a recording layer on the recording medium,
The recording layer contains a coloring material and a copolymer,
The image-formed product is characterized in that the copolymer contains a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2).
However, in said general formula (1), R < ₁ > represents a hydrogen atom or a methyl group, a represents the integer of 6-10, b represents the integer of 0 or 1.
However, In the general formula (2), _{R 2} and _{R 3} represents a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.
<18> The image forming material according to <17>, wherein the recording medium is plain paper.

  The ink according to any one of <1> to <10>, the method for producing the ink according to <11>, the ink container according to <12>, and any one of <13> to <14>. According to the image forming method described in <15>, the image forming apparatus described in <15> to <16>, and the image formed product described in <17> to <18>, The problems can be solved and the above-mentioned object of the present invention can be achieved.

400 image forming apparatus 401 exterior of image forming apparatus 401c cover of apparatus body 404 cartridge holder 410 main tanks 410k, 410c, 410m, 410y for each color of black (K), cyan (C), magenta (M), and yellow (Y) Main tank 411 Ink storage unit 413 Ink discharge port 414 Storage container case 420 Mechanism unit 434 Discharge head 436 Supply tube

JP, 2011-105866, A

Claims (11)

An ink containing water, a coloring material, and a copolymer,
An ink characterized in that the copolymer contains a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2).
However, in said general formula (1), R < ₁ > represents a hydrogen atom or a methyl group, a represents the integer of 6-10, b represents the integer of 0 or 1.
However, In the general formula (2), _{R 2} and _{R 3} represents a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90. The ink according to claim 1, wherein the structural unit represented by the general formula (2) is a structural unit represented by the following general formula (3).
However, in the general formula (3), R ₂ and R ₃ represent a hydrogen atom or a methyl group, and n represents an integer of 1 to 90.   The ink according to claim 1, wherein the content of the structural unit represented by the general formula (1) in the copolymer is 40% by mass or more and 70% by mass or less.   The ink according to claim 1, wherein the copolymer has a weight average molecular weight of 15,000 or more and 40,000 or less.   The ink according to claim 1, wherein the coloring material is a pigment.   The ink according to claim 1, further containing at least one of an organic solvent and a surfactant. A method for producing an ink containing water, a coloring material, and a copolymer,
An ink including a step of synthesizing a copolymer by radically polymerizing a compound represented by the following general formula (4) and a polymerizable material containing a compound represented by the following general formula (5). Manufacturing method.
In the general formula (4), _{R 4} represents a hydrogen atom or a methyl group, a represents an integer of 6 to 10, b represents an integer of 0 or 1.
In the general formula (5), _{R 5} and _{R 6} represent a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.   An ink containing container having an ink containing part for containing ink, wherein the ink contained in the ink containing part is the ink according to any one of claims 1 to 6. .   An image forming method comprising: an ink flying step of applying a stimulus to the ink according to claim 1 to fly the ink to form an image.   An image forming apparatus comprising: an ink flying unit that applies a stimulus to the ink according to claim 1 to fly the ink to form an image. An image formed product having a recording medium and a recording layer on the recording medium,
The recording layer contains a coloring material and a copolymer,
An image-formed product, wherein the copolymer contains a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2).
However, in said general formula (1), R < ₁ > represents a hydrogen atom or a methyl group, a represents the integer of 6-10, b represents the integer of 0 or 1.
However, In the general formula (2), _{R 2} and _{R 3} represents a hydrogen atom or a methyl group, n represents an integer of. 1 to 90, m is an integer of 0-90.