JP2015117308A - Inkjet ink and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet ink excellent in a plain paper image density and storage stability.SOLUTION: An inkjet ink contains water, a water-soluble organic solvent, a pigment and a copolymer. The copolymer has a constitutional unit represented by the general formula (1), diacetone (meth)acrylamide, and oleyl (meth)acrylate.

Description

  The present invention relates to an inkjet ink, an inkjet ink manufacturing method, an ink cartridge, an inkjet recording apparatus, and a recorded matter.

  Inkjet recording systems have become popular because they are simple in process and easy to achieve full color. The inkjet recording method is a method of forming an image by ejecting a small amount of ink with a pressure generated by using bubbles, piezo, electrostatic, etc. generated by heat and attaching it to a recording medium such as paper. Applications are expanding to personal and industrial printers and printing.

  In the ink jet recording system, a water-based dye ink in which a water-soluble dye is used as a colorant is mainly used, but the water-based dye ink generally has poor weather resistance and water resistance. For this reason, research on water-based pigment inks in which water-insoluble pigments are used instead of water-soluble dyes is underway.

  However, the aqueous pigment ink has a problem that storage stability is inferior.

  In addition, with the improvement in image quality improvement technology of OA printers, image density on plain paper is required for aqueous pigment ink.

  However, the aqueous pigment ink has a problem that the image density is lowered by permeating into plain paper.

  Patent Document 1 discloses an ink-jet ink composition comprising a) a liquid vehicle, b) at least one pigment, and c) at least one polymer. At this time, the polymer contains at least one functional group having a calcium index value equal to or higher than that of 1,2,3-benzenetricarboxylic acid.

  However, an ink-jet ink excellent in image density and storage stability on plain paper is desired.

  An object of one embodiment of the present invention is to provide an inkjet ink that is excellent in image density and storage stability in plain paper in view of the problems of the above-described conventional technology.

  One embodiment of the present invention, in an inkjet ink, includes water, a water-soluble organic solvent, a pigment, and a copolymer, and the copolymer has a general formula

（式中、Ｒ_１は、水素原子又はメチル基であり、Ｍ_１ ^＋、Ｍ_２ ^＋、Ｍ_３ ^＋及びＭ_４ ^＋は、それぞれ独立に、アルカリ金属イオン、有機アンモニウムイオン又はプロトンである。）
で表される構成単位と、一般式

(In the formula, R ₁ is a hydrogen atom or a methyl group, and M ₁ ⁺ , M ₂ ⁺ , M ₃ ⁺ and M ₄ ⁺ are each independently an alkali metal ion, an organic ammonium ion or a proton.)
And the general formula

（式中、Ｒ_２は、水素原子又はメチル基である。）
で表される構成単位と、一般式

(In the formula, R ₂ is a hydrogen atom or a methyl group.)
And the general formula

（式中、Ｒ_３は、水素原子又はメチル基である。）
で表される構成単位を有する。

(In the formula, R ₃ is a hydrogen atom or a methyl group.)
It has the structural unit represented by these.

  One embodiment of the present invention, in an inkjet ink, includes water, a water-soluble organic solvent, a pigment, and a copolymer, and the copolymer has a general formula

（式中、Ｒ_１は、水素原子又はメチル基である。）
で表される化合物と、一般式

(In the formula, R ₁ is a hydrogen atom or a methyl group.)
And a compound represented by the general formula

（式中、Ｒ_２は、水素原子又はメチル基である。）
で表される化合物と、一般式

(In the formula, R ₂ is a hydrogen atom or a methyl group.)
And a compound represented by the general formula

（式中、Ｒ_３は、水素原子又はメチル基である。）
で表される化合物を含むモノマーを共重合することにより合成されている。

(In the formula, R ₃ is a hydrogen atom or a methyl group.)
It is synthesize | combined by copolymerizing the monomer containing the compound represented by these.

  According to one embodiment of the present invention, it is possible to provide an inkjet ink that is excellent in image density and storage stability in plain paper.

It is a perspective view which shows an example of an inkjet recording device. It is the schematic which shows the inkjet recording device of FIG. It is a schematic enlarged view which shows the inkjet head of FIG. FIG. 2 is a schematic diagram illustrating the ink cartridge of FIG. 1.

  Next, the form for implementing this invention is demonstrated with drawing.

  The inkjet ink includes water, a water-soluble organic solvent, a pigment, and a copolymer. At this time, the copolymer has a structural unit represented by the general formula (1), a structural unit represented by the general formula (2), and a structural unit represented by the general formula (3).

_M ¹ _+, ^M 2 + in the general formula _(1), as the _M ^{3 +} and _M ^{4 +} definitive alkali metal ion is not particularly limited, a lithium ion, sodium ion, potassium ion, and the like. Among these, potassium ion is preferable from the viewpoint of image density on plain paper and storage stability of inkjet ink.

_M ¹ + in the general formula _(1), the _^M 2 ^{_+, M 3} + and _M ^{4 +} definitive organic ammonium ion deprotonated organic amines include, but are not limited to, monomethylamine, dimethylamine, trimethylamine, monoethylamine Alkylamines such as diethylamine and triethylamine; ethanolamine, diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, dimethylethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, trishydroxymethylaminomethane, Alcohol amines such as 2-amino-2-ethyl-1,3-propanediol; choline, morpholine, N-methylmonoformin, N-methyl-2-pyrrolidone And cyclic amines such as 2-pyrrolidone.

Of M ₁ ⁺ , M ₂ ⁺ , M ₃ ⁺ and M ₄ ⁺ , two or more are preferably alkali metal ions or organic amine ions, and more preferably all are alkali metal ions or organic amine ions. .

  Content of the structural unit represented by General formula (1) in a copolymer is 5-80 mass% normally, It is preferable that it is 10-60 mass%, and it is 20-40 mass%. Is more preferable. When the content of the structural unit represented by the general formula (1) in the copolymer is 10% by mass or more, the image density on plain paper can be improved. On the other hand, when the content of the structural unit represented by the general formula (1) in the copolymer is 60% by mass or less, the storage stability of the inkjet ink can be improved.

  Content of the structural unit represented by General formula (1) in a copolymer can be calculated | required by measuring the acid value of a copolymer.

  First, after dissolving the copolymer in a predetermined amount of water, a 0.1N potassium hydroxide methanol solution as a neutralizing reagent is dropped, and the acid value is calculated from the titration amount when the indicator is discolored. A thymolphthalein solution is used as an indicator.

Assuming that the mass of the copolymer is A [g], the titration of the 0.1N potassium hydroxide methanol solution is B [mL], and the factor of the 0.1N potassium hydroxide methanol solution is f, the formula B × 5.611 × f / A
From this, the acid value can be calculated.

Next, when the acid value of the monomer represented by the general formula (3) is C and the acid value of the copolymer is D, the content of the structural unit represented by the general formula (1) in the copolymer [ % By mass is the formula X = D / C × 100
Can be obtained from

  Content of the structural unit represented by General formula (2) in a copolymer is 10-60 mass% normally, and it is preferable that it is 35-45 mass%. When the content of the structural unit represented by the general formula (2) in the copolymer is 10% by mass or more, the storage stability of the inkjet ink can be improved. On the other hand, when the content of the structural unit represented by the general formula (2) in the copolymer is 60% by mass or less, the image density on plain paper can be improved.

  Content of the structural unit represented by General formula (3) in a copolymer is 10-45 mass% normally, and it is preferable that it is 30-35 mass%. When the content of the structural unit represented by the general formula (3) in the copolymer is 10% by mass or more, the image density on plain paper can be improved. On the other hand, when the content of the structural unit represented by the general formula (3) in the copolymer is 45% by mass or less, the storage stability of the inkjet ink can be improved.

  The copolymer can be used as a pigment dispersant, a binder resin, a viscosity modifier, and the like. Among these, from the viewpoint of image density on plain paper and storage stability of inkjet ink, the copolymer is preferably used as a pigment dispersant.

  The copolymer is necessary after copolymerizing a compound represented by the general formula (4), a compound represented by the general formula (5), and a monomer containing the compound represented by the general formula (6). Accordingly, it can be synthesized by neutralization with an alkali metal base and / or an organic amine base.

  Examples of the compound represented by the general formula (4) include 1-methacryloyloxyethane-1,1-diphosphonic acid and 1-acryloyloxyethane-1,1-diphosphonic acid. Of these, 1-methacryloyloxyethane-1,1-diphosphonic acid is preferable from the viewpoint of image density on plain paper.

  The method for synthesizing the compound represented by the general formula (4) is not particularly limited, and examples thereof include a synthesis method described in JP-A No. 58-2222095.

  Examples of the compound represented by the general formula (5) include diacetone acrylamide and diacetone methacrylamide. Of these, diacetone acrylamide is preferable from the viewpoint of storage stability.

  Examples of the compound represented by the general formula (6) include oleyl acrylate and oleyl methacrylate. Among these, oleyl acrylate is preferable from the viewpoint of image density kicked by plain paper.

  The monomer may further include a monomer other than the compounds represented by the general formulas (4) to (6).

  As monomers other than the compounds represented by the general formulas (4) to (6), hydrophobic monomers and hydrophilic monomers can be used.

  The hydrophobic monomer is not particularly limited, but is an unsaturated ethylene monomer having an aromatic ring such as styrene, α-methylstyrene, 4-t-butylstyrene, 4-chloromethylstyrene; methyl (meth) acrylate, ( (Meth) ethyl acrylate, n-butyl (meth) acrylate, dimethyl maleate, dimethyl itaconate, dimethyl fumarate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, (meta ) Pentadecyl acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, heicosyl (meth) acrylate, docosyl (meth) acrylate, ) Alkyl acrylate; 1-heptene, 3,3-di Tyl-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- Examples include unsaturated ethylene monomers having an alkyl group such as dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 1-docose. Two or more kinds may be used in combination.

  The hydrophilic monomer is not particularly limited, and (meth) acrylic acid or a salt thereof, maleic acid or a salt thereof, monomethyl maleate, itaconic acid, monomethyl itaconic acid, fumaric acid, 4-styrenesulfonic acid, 2-acrylamide- Anionic unsaturated ethylene monomers such as 2-methylpropanesulfonic acid; 2-hydroxyethyl (meth) acrylate, diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, Polyethylene glycol mono (meth) acrylate, (meth) acrylamide, N-methylol (meth) acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, acrylamide, N, N-dimethyl Acrylamide, N-t-butylacrylamide, N- octyl acrylamide, nonionic ethylenically unsaturated monomers such as N-t-octyl acrylamide, and the like, may be used in combination of two or more.

  When the copolymer is used as a pigment dispersant, the monomer preferably further contains a hydrophobic monomer.

  As a method for copolymerizing the monomer, a method of copolymerizing the monomer using a radical polymerization initiator is preferable because the polymerization operation and the adjustment of the molecular weight are easy, and a solution weight for copolymerizing the monomer in an organic solvent is preferable. Legal is more preferred.

  The organic solvent is not particularly limited, but ketone solvents such as methanol, ethanol, acetone, methyl ethyl ketone and methyl isobutyl ketone; acetate solvents such as ethyl acetate and butyl acetate; aromatic hydrocarbons such as benzene, toluene and xylene Examples of the solvent include alcohol solvents such as isopropanol and ethanol; cyclohexane, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, hexamethylphosphoamide and the like. Of these, ketone solvents, acetate solvents, and alcohol solvents are preferred.

  The radical polymerization initiator is not particularly limited, but peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, cyano azobisisobutyronitrile, azobis (2 -Methylbutyronitrile), 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 more preferable because the molecular weight is easily controlled and the decomposition temperature is low.

  The ratio of the mass of the polymerization initiator to the total mass of the monomers is usually 0.01 to 0.1.

  In order to adjust the molecular weight of the copolymer, a chain transfer agent may be added.

  Examples of the chain transfer agent include, but are not limited to, mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, dodecyl mercaptan, 1-dodecanethiol, thioglycerol, and the like.

  The polymerization temperature is usually 50 to 150 ° C, preferably 60 to 100 ° C.

  The polymerization time is usually 3 to 48 hours.

  In the inkjet ink production process, the copolymer may be neutralized in a state of being mixed with a pigment.

  The weight average molecular weight of the copolymer is usually 3000 to 60000, and preferably 4000 to 50000. When the weight average molecular weight of the copolymer is 4000 or more, the image density can be further improved, and when it is 50000 or less, the storage stability of the inkjet ink can be further improved.

  In addition, the weight average molecular weight of a copolymer can be measured using a gel permeation chromatography (GPC).

  The weight average molecular weight of the copolymer can be controlled by the polymerization temperature, the addition amount of the polymerization initiator, and the monomer concentration during the copolymerization. Specifically, when a monomer is copolymerized at a high temperature for a short time, a low molecular weight copolymer is obtained, and when a monomer is copolymerized at a low temperature for a long time, a high molecular weight copolymer is obtained. Further, when the addition amount of the radical polymerization initiator is large, a low molecular weight copolymer is obtained, and when the addition amount of the radical polymerization initiator is small, a high molecular weight polymer is obtained. Further, when the monomer concentration during copolymerization is high, a low molecular weight copolymer is obtained, and when the monomer concentration during copolymerization is low, a high molecular weight copolymer is obtained.

  The structural unit represented by the general formula (1) has a tetrabasic acid structure in which phosphonic acid groups are adjacent to each other, and the copolymer has many diphosphonic acid groups in the molecule. As a result, the structural unit represented by the general formula (1) can impart a large number of hydrophilic groups to the copolymer as compared with the structural unit having a monobasic acid structure, and has good hydrophilicity. Show. In addition, the structural unit represented by the general formula (1) has a tetrabasic acid structure in which a phosphonic acid group that easily reacts with calcium ions is adjacent, and thus has an effect of chelating calcium ions. Can be hydrophobized when contacted.

  The structural unit represented by the general formula (2) brings hydrophilicity to the copolymer. In addition, it is presumed that the structural unit represented by the general formula (2) can suppress the association of phosphonic acid groups in the copolymer and can improve the storage stability of the inkjet ink.

  The structural units represented by the general formulas (2) and (3) can improve the adsorptivity of the copolymer to the pigment, and as a result, the copolymer can be used as a pigment dispersant.

  Therefore, even if an image is recorded on plain paper with a low calcium ion content using an inkjet ink containing the copolymer, the copolymer becomes hydrophobic due to the calcium ions eluted from the plain paper to the inkjet ink. In this case, the pigment stays on the surface of the plain paper and the image density can be improved.

  The content of the copolymer in the inkjet ink is usually 0.05 to 10% by mass, preferably 0.5 to 5% by mass, and more preferably 1 to 3% by mass. When the content of the copolymer in the inkjet ink is 0.05% by mass or more, the image density in plain paper and the storage stability of the inkjet ink can be improved, and by being 10% by mass or less, Ink jet ink ejection stability can be improved.

  When the copolymer is used as a pigment dispersant, the mass ratio of the copolymer to the pigment is usually 0.01 to 1, preferably 0.05 to 0.8, preferably 0.1 to 0. More preferably, it is 5. Thereby, the image density in plain paper and the storage stability of inkjet ink can be improved.

  As water, pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water can be used.

  Although it does not specifically limit as a pigment, A black or color inorganic pigment, an organic pigment, etc. are mentioned, You may use 2 or more types together.

  Examples of inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black.

  Although it does not specifically limit as a manufacturing method of carbon black, A contact method, a furnace method, a thermal method etc. are mentioned.

  Examples of organic pigments include azo pigments, azomethine pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Of these, azo pigments and polycyclic pigments are preferred.

  Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments.

  Examples of the polycyclic pigment include a phthalocyanine pigment, a perylene pigment, a perinone pigment, an anthraquinone pigment, a quinacridone pigment, a dioxazine pigment, an indigo pigment, a thioindigo pigment, an isoindolinone pigment, a quinofullerone pigment, and a rhodamine B lake pigment.

  Examples of the dye chelates include basic dye chelates and acidic dye chelates.

  Black pigments include carbon black (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, channel black, copper, iron (CI Pigment Black 11), and inorganic such as titanium oxide. And organic pigments such as pigment and aniline black (CI Pigment Black 1).

  The average primary particle size of carbon black is usually 15 to 40 nm.

The BET specific surface area of carbon black is usually 50 to 300 m ² / g.

  The DBP oil absorption of carbon black is usually 40 to 150 mL / 100 g.

  The volatile content of carbon black is usually 0.5 to 10%.

  The pH of carbon black is usually 2-9.

  As a commercial product of carbon black, No. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (above, manufactured by Mitsubishi Chemical Corporation), Raven700, 5750, 5250, 5000, 3500, 1255 (above, manufactured by Columbia), Regal400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (above, manufactured by Cabot Corporation), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, 4 (Above, manufactured by Degussa).

  Examples of yellow pigments 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. And CI Pigment Yellow 180.

  Examples of the magenta pigment include C.I. 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.

  Examples of cyan pigments 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. Examples include Bat Blue 60.

  As a yellow pigment, C.I. I. Pigment Yellow 74, a pigment for magenta, C.I. I. Pigment red 122, C.I. I. Pigment Bio Red 19, a pigment for cyan, C.I. I. When CI Pigment Blue 15: 3 is used, a well-balanced inkjet ink having excellent color tone and light resistance can be obtained.

  The volume median diameter (D50) of the pigment is usually 150 nm or less, preferably 100 nm or less. Thereby, the ejection stability of inkjet ink can be improved.

  The volume median diameter (D50) of the pigment can be measured by a dynamic light scattering method using Microtrac UPA (manufactured by Nikkiso Co., Ltd.) in an environment of 23 ° C. and 55% RH.

  The content of the pigment in the inkjet ink is usually 0.1 to 20% by mass, and preferably 1 to 20% by mass.

  When producing an inkjet ink, it is preferable to prepare a pigment dispersion by dispersing a composition containing water, a pigment, and a pigment dispersant using a disperser.

  When preparing the pigment dispersion, it is preferable to filter out coarse particles by using a filter, a centrifugal separator or the like, and deaerate.

  The content of the pigment in the pigment dispersion is usually 0.1 to 50% by mass, and preferably 0.1 to 30% by mass.

  Examples of the pigment dispersant include surfactants such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant, and two or more of them may be used in combination. Among these, from the viewpoint of image density on plain paper and storage stability of inkjet ink, the above-mentioned copolymer is preferable.

  Examples of anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acyl amino acids and salts thereof, N-acyl methyl taurates, polyoxyalkyl ether sulfates. , Polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester salt, lauryl alcohol sulfate ester salt, alkylphenol type phosphate ester, naphthalene sulfonic acid formalin condensate salt, alkyl type phosphate ester, alkyl allyl sulfone hydrochloride , Diethylsulfosuccinate, diethylhexylsulfosuccinate, dioctylsulfosuccinate and the like.

  Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly (4-vinylpyridine derivatives).

  Examples of amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, imidazoline derivatives, etc. Is mentioned.

  Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyallyl Ether-based surfactants such as kill alkyl ethers; polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, poly Ester surfactants such as oxyethylene monooleate and polyoxyethylene stearate; 2,4,7,9-tetramethyl-5- Shin-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyne-3-acetylene glycol surface active agents such as all-like.

  Among these, naphthalenesulfonic acid formalin condensate sodium salt is preferable.

  The content of 2- to 4-mer of naphthalenesulfonic acid in the naphthalenesulfonic acid formalin condensate sodium salt is usually 20 to 80% by mass. The storage stability of the ink-jet ink can be improved when the content of a dimer or tetramer of naphthalenesulfonic acid in the sodium salt of naphthalenesulfonic acid formalin condensate is 20% by mass or more. On the other hand, the ejection stability of the inkjet ink can be improved by the content of the naphthalene sulfonic acid formalin condensate sodium salt having a dimer or tetramer of naphthalene sulfonic acid of 80% by mass or less.

  The water-soluble organic solvent has an effect as a wetting agent that suppresses drying of the inkjet ink and / or an effect as a penetrating agent.

  The water-soluble organic solvent is not particularly limited, but glycerin, ethylene glycol, diethylene glycol, isopropylideneglycerol, 1,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, propylene glycol, dipropylene Glycol, trimethylolpropane, trimethylolethane, ethylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol , 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol and other polyhydric alcohols Polyhydric alcohol alkyl ethers 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, propylene glycol monoethyl ether; ethylene glycol monophenyl ether; Polyhydric alcohol aryl ethers such as ethylene glycol monobenzyl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ- Nitrogen-containing heterocyclic compounds such as butyrolactone; formamide, N-methylformamide, N, N-dimethylphenol Amides such as muamide, N, N-dimethyl-β-methoxypropionamide, N, N-dimethyl-β-butoxypropionamide; amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine; dimethyl Sulfur-containing compounds such as sulfoxide, sulfolane, thiodiethanol; 3-ethyl-3-hydroxymethyloxetane, propylene carbonate, ethylene carbonate, and the like may be mentioned, and two or more kinds may be used in combination. Among these, 3-ethyl-3-hydroxymethyloxetane, isopropylideneglycerol, N, N-dimethyl-β-methoxypropionamide, and N, N-dimethyl-β-butoxypropionamide are preferred because they prevent curling in plain paper. preferable. In addition, 1,3-butanediol, diethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol, and glycerin are preferable from the viewpoint of preventing discharge failure due to water evaporation.

  Examples of water-soluble organic solvents having relatively low wettability and permeability include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.

  Other aliphatic diols include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1,3-propanediol, -Methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1,2-diol, etc. Is mentioned.

  Other penetrants include alkyls of polyhydric alcohols such as diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, and tetraethylene glycol chlorophenyl ether. And lower alcohols such as aryl ether and ethanol.

  As the wetting agent other than the water-soluble organic solvent, saccharides such as monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and derivatives thereof can be used.

  Examples of the saccharide include, but are not limited to, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and the like.

  Here, the polysaccharide means a saccharide in a broad sense and includes substances widely present in nature such as α-cyclodextrin and cellulose.

Derivatives of sugars include reducing sugars of sugars (for example, the general formula HOCH ₂ (CHOH) _n CH ₂ OH
(However, n is an integer of 2 to 5.)
Sugar alcohols represented by the formula :), oxidized sugars (for example, aldonic acid, uronic acid), amino acids, thioic acids and the like. Of these, sugar alcohols are preferred.

  Examples of the sugar alcohol include maltitol and sorbit.

  The content of the water-soluble organic solvent in the inkjet ink is usually 10 to 60% by mass, and preferably 20 to 60% by mass. When the content of the water-soluble organic solvent in the inkjet ink is 10% by mass or more, the ejection stability of the inkjet ink can be improved. On the other hand, when the content of the water-soluble organic solvent in the inkjet ink is 60% by mass or less, the drying property of the inkjet ink can be improved.

  The inkjet ink may further contain a surfactant, a pH adjuster, a water-dispersible resin, an antiseptic / antifungal agent, a rust inhibitor, an antioxidant, an ultraviolet absorber, an oxygen absorber, a light stabilizer, and the like.

  The surfactant is not particularly limited, and examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, and a fluorosurfactant. Of these, nonionic surfactants and fluorosurfactants are preferred.

  Anionic surfactants include alkyl naphthalene sulfonate, alkyl phosphate, alkyl sulfate, alkyl sulfonate, alkyl ether sulfate, alkyl sulfosuccinate, alkyl ester sulfate, alkyl benzene sulfonate, alkyl diphenyl ether Disulfonate, alkylaryl ether phosphate, alkylaryl ether sulfate, alkylaryl ether ester sulfate, olefin sulfonate, alkane olefin sulfonate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl ether sulfate Examples thereof include ester salts, ether carboxylates, sulfosuccinates, α-sulfo fatty acid esters, fatty acid salts, condensates of higher fatty acids and amino acids, and naphthenates.

  Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalkonium salts, quaternary ammonium salts, alkylpyridinium salts, imidazolinium salts, sulfonium salts, phosphonium salts, and the like.

  Nonionic surfactants include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like.

  Examples of amphoteric surfactants include imidazoline derivatives such as imidazolinium betaine, dimethylalkyllauryl betaine, alkylglycine, and alkylbis (aminoethyl) glycine.

  Examples of the fluorine-based surfactant include compounds represented by general formulas (I) to (III).

（式中、ｍは０〜１０の整数であり、ｎは１〜４０の整数である。）

(In the formula, m is an integer of 0 to 10, and n is an integer of 1 to 40.)

（式中、Ｒｆは、パーフルオロアルキル基であり、ｎは１〜４の整数であり、ｍは６〜２５の整数であり、ｐは１〜４の整数である。）

(In the formula, Rf is a perfluoroalkyl group, n is an integer of 1 to 4, m is an integer of 6 to 25, and p is an integer of 1 to 4).

（式中、Ｒｆは、パーフルオロアルキル基であり、Ｒ_１ ⁻は、アニオン性基であり、Ｒ_２ ^＋は、カチオンであり、ｑは１〜６の整数である。）
一般式（ＩＩ）、（ＩＩＩ）において、パーフルオロアルキル基の炭素数は、通常、１〜１０であり、１〜３であることが好ましい。

(In the formula, Rf is a perfluoroalkyl group, R ₁ ⁻ is an anionic group, R ₂ ⁺ is a cation, and q is an integer of 1 to 6.)
In general formula (II), (III), carbon number of a perfluoroalkyl group is 1-10 normally, and it is preferable that it is 1-3.

  The perfluoroalkyl group is not particularly limited, and examples thereof include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropentyl group, and a nonafluorobutyl group. Of these, a trifluoromethyl group and a pentafluoroethyl group are preferable.

In the general formula (III), the anionic group is not particularly limited, and examples thereof include COO ⁻ and SO ₃ ^— .

  In the general formula (III), the cation is not particularly limited, and examples thereof include quaternary ammonium ions; alkali metal ions such as sodium ions and potassium ions; triethylammonium ions and triethanolammonium ions. Of these, quaternary ammonium ions are preferred.

  Commercially available fluorosurfactants include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (above, manufactured by Asahi Glass Co., Ltd.) Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (above, manufactured by Sumitomo 3M); Megafac F-470, F1405, F-474 (above, manufactured by DIC); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (above, manufactured by DuPont); FT-110, FT-250 , FT-251, FT-400S, FT-150, FT-400SW (above, manufactured by Neos); PF-151N (manufactured by Solutions Incorporated) And the like.

  The content of the surfactant in the inkjet ink is usually 0.01 to 5.0% by mass, and preferably 0.5 to 3% by mass. When the content of the surfactant in the ink-jet ink is 5.0% by mass or less, it is possible to improve the image density of plain paper and to prevent the occurrence of show-through.

  The pH adjuster is not particularly limited as long as the pH can be adjusted to 8.5 to 11, but alcohol amine, alkali metal hydroxide, alkali metal carbonate, ammonium hydroxide, quaternary ammonium hydroxide, hydroxide Quaternary phosphonium etc. are mentioned.

  Examples of the alcohol amine include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol and the like.

  Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.

  Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

  The water-dispersible resin is not particularly limited, and examples thereof include condensation-type synthetic resins, addition-type synthetic resins, and natural polymer compounds.

  Examples of the condensed synthetic resin include polyester, polyurethane, epoxy resin, polyamide, polyether resin, (meth) acrylic resin, acrylic-silicone resin, and fluorine-based resin.

  Examples of the addition type synthetic resin include polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, and the like.

  Examples of the natural polymer compound include cellulose, rosin, natural rubber and the like.

  Of these, polyurethane, acrylic-silicone resin and fluorine-based resin are preferable.

  The median diameter (D50) of the water-dispersible resin is usually 50 to 200 nm.

  The minimum film forming temperature (MFT) of the water dispersible resin is usually 30 ° C. or lower.

  The glass transition temperature of the water dispersible resin is usually −30 ° C. or higher.

  The content of the water-dispersible resin in the inkjet ink is usually 1 to 15% by mass, and preferably 2 to 7% by mass.

  The antiseptic / antifungal agent is not particularly limited, and examples thereof include sodium dehydroacetate, sodium sorbate 2-pyridinethiol-1-oxide sodium, sodium benzoate, and sodium pentachlorophenol.

  The rust inhibitor is not particularly limited, and examples thereof include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Although it does not specifically limit as antioxidant, A phenolic antioxidant (a hindered phenolic antioxidant is included), an amine antioxidant, a sulfuric antioxidant, phosphorus antioxidant, etc. are mentioned.

  Although it does not specifically limit as a ultraviolet absorber, A benzophenone type ultraviolet absorber, a benzotriazole type ultraviolet absorber, a salicylate type ultraviolet absorber, a cyanoacrylate type ultraviolet absorber, a nickel complex salt type ultraviolet absorber, etc. are mentioned.

  The ink-jet ink can be produced by dissolving or dispersing a composition containing a water-soluble organic solvent, a pigment and a copolymer in water and then stirring.

  When manufacturing an inkjet ink, it is preferable to filter out coarse particles by a filter, a centrifugal separator, or the like as necessary.

  The disperser used when dissolving or dispersing the composition in water is not particularly limited, and examples thereof include a sand mill, a homogenizer, a ball mill, a paint shaker, and an ultrasonic disperser.

  The stirrer used when stirring the water in which the composition is dissolved or dispersed is not particularly limited, and examples thereof include a stirrer using a stirring blade, a magnetic stirrer, and a high-speed disperser.

  The viscosity at 25 ° C. of the inkjet ink is usually 3 to 20 mPa · s, and preferably 5 to 12 mPa · s. When the viscosity of the inkjet ink at 25 ° C. is 3 mPa · s or more, the image density and the character quality can be improved. On the other hand, when the viscosity of the inkjet ink at 25 ° C. is 20 mPa · s or less, the ejection stability of the ink can be improved.

  The viscosity of the inkjet ink at 25 ° C. can be measured using a viscometer RE80L (manufactured by Toki Sangyo Co., Ltd.).

  The surface tension of inkjet ink at 25 ° C. is usually 40 mN / m or less.

  The recording medium on which an image is recorded by inkjet ink is not particularly limited, and examples thereof include plain paper, printing coated paper, glossy paper, and special paper.

  The above recording medium contains calcium carbonate, talc, kaolin, aluminum sulfate (sulfate band), etc., and multivalent metal ions (for example, calcium, magnesium, aluminum) are eluted when ink jet ink is attached. To do.

  Ink-jet ink generally reacts with polyvalent metal ions and aggregates to record an image having excellent image density.

  However, many of fillers, sizing agent fixing agents and the like contained in plain paper are poorly water-soluble metal salts, and the content of water-soluble metal salts in plain paper is small. For this reason, plain paper generally has less elution amount of polyvalent metal ions and it is difficult to improve the image density compared to paper in which water-soluble polyvalent metal salts and the like are processed on the paper surface. .

  On the other hand, the above-described inkjet ink can record an image having excellent image density even on plain paper with a small amount of polyvalent metal ions.

  FIG. 1 shows an example of an ink jet recording apparatus.

  The ink jet recording apparatus 100 includes an apparatus main body 101 and an ink cartridge 200 that is detachably attached to the apparatus main body 101.

  The apparatus main body 101 includes a paper feed tray 102 for feeding paper, a paper discharge tray 103 for stocking paper on which an image is recorded, and an ink cartridge loading unit 104. Have.

  On the top surface of the ink cartridge loading unit 104, an operation unit 105 such as operation keys and a display is arranged. The ink cartridge loading unit 104 has a front cover 115 that can be opened and closed to detach the ink cartridge 200.

  In the apparatus main body 101, as shown in FIGS. 2 and 3, a carriage 133 is slidably held by a guide rod 131 and a stay 132 which are horizontally mounted on left and right side plates (not shown). A main scanning motor (not shown) moves and scans in the main scanning direction X.

  The carriage 133 includes four inkjet heads 134 that eject inkjet inks of each color of yellow (Y), cyan (C), magenta (M), and black (Bk), and a plurality of ink ejection ports are arranged in the main scanning direction X. And is mounted so that the direction of ink jet ink discharge is downward.

  The inkjet head 134 has energy generating means for ejecting inkjet ink.

  The energy generation means is not particularly limited, but a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. Examples thereof include a shape memory alloy actuator to be used and an electrostatic actuator using an electrostatic force.

  In addition, the carriage 133 is equipped with a sub tank 135 for each color for supplying the inkjet ink of each color to the inkjet head 134. The sub tank 135 is supplied with ink-jet ink from the ink cartridge 200 loaded in the ink cartridge loading unit 104 via an ink supply tube (not shown) and is replenished.

  On the other hand, the apparatus main body 101 separates the sheets 142 from the sheet stacking unit 141 one by one as a sheet feeding unit for feeding the sheets 142 stacked on the sheet stacking unit (pressure plate) 141 of the sheet feeding tray 102. There is a separating pad 144 made of a material having a large friction coefficient, facing the feeding half-moon roller (sheet feeding roller) 143 and the sheet feeding roller 143, and the separation pad 144 is urged toward the sheet feeding roller 143 side. .

  Further, the apparatus main body 101 serves as a transport unit for transporting the paper 142 fed from the paper feed unit on the lower side of the inkjet head 134, a transport belt 151 for transporting the paper 142 by electrostatic adsorption, A counter roller 152 for transporting the paper 142 transported from the paper supply unit via the guide 145 between the transport belt 151 and the paper 142 transported substantially vertically upward is changed by approximately 90 °. A conveyance guide 153 for following the conveyance belt 151 and a tip pressure roller 155 urged toward the conveyance belt 151 by a pressing member 154 are provided.

  Further, the apparatus main body 101 includes a charging roller 156 for charging the surface of the conveyance belt 151.

  The conveyance belt 151 is an endless belt, is supported by a conveyance roller 157 and a tension roller 158, and can circulate in the belt conveyance direction Y.

  The conveyance belt 151 is, for example, a surface layer serving as a sheet adsorption surface formed of a resin having a thickness of about 40 μm (for example, a polymer of tetrafluoroethylene and ethylene (ETFE)), and resistance is controlled by carbon. Has a back layer (medium resistance layer, ground layer) made of the same material as the surface layer.

  A guide member 161 is disposed on the back side of the conveyance belt 151 so as to correspond to an image recording area by the inkjet head 134.

  The apparatus main body 101 serves as a paper discharge unit for discharging the paper 142 on which an image has been recorded by the ink jet head 134, and includes a separation claw 171 for separating the paper 142 from the transport belt 151, a paper discharge roller 172 A paper discharge roller 173 is provided, and a paper discharge tray 103 is disposed below the paper discharge roller 172.

  A double-sided paper feeding unit 181 is detachably mounted on the back surface of the apparatus main body 101. The double-sided paper feeding unit 181 takes in the paper 142 returned by the rotation of the transport belt 151 in the reverse direction, reverses it, and feeds it again between the counter roller 152 and the transport belt 151.

  A manual paper feed unit 182 is provided on the upper surface of the duplex paper feed unit 181.

  In the inkjet recording apparatus 100, the sheet 142 is separated and fed one by one from the sheet feeding unit, and the sheet 142 fed substantially vertically upward is guided by the guide 145, and is interposed between the conveyance belt 151 and the counter roller 152. It is sandwiched and conveyed. Further, after the leading edge of the paper 142 is guided by the conveying guide 153, the sheet 142 is pressed against the conveying belt 151 by the leading edge pressing roller 155, and the conveying direction is changed by approximately 90 °.

  At this time, the conveyance belt 151 is charged by the charging roller 156, and the sheet 142 is conveyed by being electrostatically attracted to the conveyance belt 151. Therefore, by moving the carriage 133 and driving the ink jet head 134 according to the image signal, the ink jet ink is ejected onto the stopped paper 142 to record one line. Further, after the sheet 142 is conveyed by a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 142 has reached the image recording area, the recording operation is finished and the paper 142 is discharged onto the paper discharge tray 103.

  When a near-end of the ink jet ink in the sub tank 135 is detected, a required amount of ink jet ink is supplied from the ink cartridge 200 to the sub tank 135.

  FIG. 4 shows the ink cartridge 200.

  The ink cartridge 200 is closed by fusing the ink injection port 242 after filling the ink bag 241 with ink-jet ink from the ink injection port 242 and exhausting it. In use, the needle of the apparatus main body 101 is pierced into the ink discharge port 243 made of a rubber member and supplied to the apparatus main body 101.

  The ink bag 241 is formed of a packaging member such as a non-permeable aluminum laminate film. The ink bag 241 is accommodated in a plastic cartridge case 244 and is detachably attached to the apparatus main body 101.

  In the inkjet recording apparatus 100, when the inkjet ink in the ink cartridge 200 is used up, the cartridge case 244 can be disassembled and only the ink bag 241 inside can be replaced.

  Further, the ink cartridge 200 can stably supply ink-jet ink even when the ink cartridge 200 is vertically placed and has a front loading configuration. Therefore, even when the upper part of the apparatus main body 101 is closed, for example, when stored in a rack, or when an object is placed on the upper surface of the apparatus main body 101, the ink The cartridge 200 can be easily replaced.

  Although the serial type (shuttle type) ink jet recording apparatus scanned by the carriage has been described here, the above-described ink jet ink can be similarly applied to a line type ink jet recording apparatus having a line type head.

  The ink jet recording apparatus 100 can be applied to an ink jet printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like.

  Examples of the present invention will be described below, but the present invention is not limited to the examples. In addition, a part means a mass part.

(Preparation of 10 mass% aqueous solution of copolymer 1)
In a flask equipped with a stirrer, thermometer and nitrogen inlet tube, 500 parts of ethanol, chemical formula

で表される化合物（１−メタクリロイルオキシエタン−１，１−ジホスホン酸）３０部、化学式

30 parts of a compound represented by the formula (1-methacryloyloxyethane-1,1-diphosphonic acid), chemical formula

で表される化合物（ダイアセトンアクリルアミド）３５部、化学式

35 parts of a compound represented by the formula (diacetone acrylamide), chemical formula

で表される化合物（アクリル酸オレイル）３５部及び重合開始剤アゾビスイソブチロニトリル４部を仕込んだ後、６５℃まで昇温した。次に、窒素気流下、１５時間重合した後、仕込んだエタノールの半量程度を留去した。さらに、アセトン中に投入した後、乾燥させ、共重合体１の前駆体を得た。

Was charged with 35 parts of a compound (oleyl acrylate) and 4 parts of a polymerization initiator azobisisobutyronitrile, and the temperature was raised to 65 ° C. Next, after polymerization for 15 hours under a nitrogen stream, about half of the charged ethanol was distilled off. Furthermore, after throwing in acetone, it was made to dry and the precursor of the copolymer 1 was obtained.

  While diluting the precursor of copolymer 1 with water, potassium hydroxide was added so that the neutralization rate was 100%, and then diluted with water to obtain a 10% by mass aqueous solution of copolymer 1. . Copolymer 1 had a weight average molecular weight of 31,000.

(Preparation of 10 mass% aqueous solution of copolymer 2)
Instead of 1-methacryloyloxyethane-1,1-diphosphonic acid, the chemical formula

で表される化合物（１−アクリロイルオキシエタン−１，１−ジホスホン酸）を用いた以外は、共重合体１の１０質量％水溶液と同様にして、共重合体２の１０質量％水溶液を得た。共重合体２は、重量平均分子量が２８０００であった。

A 10 mass% aqueous solution of copolymer 2 is obtained in the same manner as the 10 mass% aqueous solution of copolymer 1, except that the compound represented by formula (1-acryloyloxyethane-1,1-diphosphonic acid) is used. It was. Copolymer 2 had a weight average molecular weight of 28,000.

(Preparation of 10 mass% aqueous solution of copolymer 3)
Chemical formula instead of diacetone acrylamide

で表される化合物（ダイアセトンメタクリルアミド）を用いた以外は、共重合体１の１０質量％水溶液と同様にして、共重合体３の１０質量％水溶液を得た。共重合体３は、重量平均分子量が３２０００であった。

The 10 mass% aqueous solution of the copolymer 3 was obtained like the 10 mass% aqueous solution of the copolymer 1 except having used the compound (diacetone methacrylamide) represented by these. Copolymer 3 had a weight average molecular weight of 32,000.

(Preparation of 10 mass% aqueous solution of copolymer 4)
Chemical formula instead of oleyl acrylate

で表される化合物（メタクリル酸オレイル）を用いた以外は、共重合体１の１０質量％水溶液と同様にして、共重合体４の１０質量％水溶液を得た。共重合体４は、重量平均分子量が３３０００であった。

The 10 mass% aqueous solution of the copolymer 4 was obtained like the 10 mass% aqueous solution of the copolymer 1 except having used the compound represented by these (oleyl methacrylate). Copolymer 4 had a weight average molecular weight of 33,000.

(Preparation of 10 mass% aqueous solution of copolymer 5)
Except for using 1-acryloyloxyethane-1,1-diphosphonic acid, diacetone methacrylamide and oleyl methacrylate in place of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate, respectively. Obtained the 10 mass% aqueous solution of the copolymer 5 like the 10 mass% aqueous solution of the copolymer 1. Copolymer 5 had a weight average molecular weight of 35,000.

(Preparation of 10 mass% aqueous solution of copolymer 6)
A 10 mass% aqueous solution of copolymer 6 was obtained in the same manner as the 10 mass% aqueous solution of copolymer 1 except that the polymerization temperature and the polymerization time were changed to 75 ° C and 3 hours, respectively. Copolymer 6 had a weight average molecular weight of 3100.

(Preparation of 10 mass% aqueous solution of copolymer 7)
A 10 mass% aqueous solution of copolymer 7 was obtained in the same manner as the 10 mass% aqueous solution of copolymer 1 except that the polymerization temperature and the polymerization time were changed to 70 ° C and 3 hours, respectively. The copolymer 7 had a weight average molecular weight of 4200.

(Preparation of 10 mass% aqueous solution of copolymer 8)
A 10 mass% aqueous solution of copolymer 8 was obtained in the same manner as the 10 mass% aqueous solution of copolymer 1 except that the polymerization temperature and the polymerization time were changed to 50 ° C and 24 hours, respectively. Copolymer 8 had a weight average molecular weight of 50,000.

(Preparation of 10 mass% aqueous solution of copolymer 9)
A 10 mass% aqueous solution of copolymer 9 was obtained in the same manner as the 10 mass% aqueous solution of copolymer 1 except that the polymerization temperature and the polymerization time were changed to 50 ° C and 48 hours, respectively. The copolymer 9 had a weight average molecular weight of 70000.

(Preparation of 10 mass% aqueous solution of copolymer 10)
10 mass% aqueous solution of copolymer 6 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 5 parts, 60 parts and 35 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 10 was obtained. The copolymer 10 had a weight average molecular weight of 3000.

(Preparation of 10 mass% aqueous solution of copolymer 11)
10% by weight aqueous solution of Copolymer 7 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 5 parts, 60 parts and 35 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 11 was obtained. The copolymer 11 had a weight average molecular weight of 4000.

(Preparation of 10 mass% aqueous solution of copolymer 12)
10% by mass aqueous solution of Copolymer 8 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 5 parts, 60 parts and 35 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 12 was obtained. The copolymer 12 had a weight average molecular weight of 49000.

(Preparation of 10 mass% aqueous solution of copolymer 13)
10% by weight aqueous solution of Copolymer 9 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 5 parts, 60 parts and 35 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 13 was obtained. The copolymer 13 had a weight average molecular weight of 69000.

(Preparation of 10 mass% aqueous solution of copolymer 14)
10 mass% aqueous solution of copolymer 6 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 10 parts, 45 parts and 45 parts, respectively. Similarly, a 10 mass% aqueous solution of copolymer 14 was obtained. The copolymer 14 had a weight average molecular weight of 3200.

(Preparation of 10% by mass aqueous solution of copolymer 15)
10% by weight aqueous solution of Copolymer 7 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 10 parts, 45 parts and 45 parts, respectively. Similarly, a 10 mass% aqueous solution of copolymer 15 was obtained. The copolymer 15 had a weight average molecular weight of 4300.

(Preparation of 10 mass% aqueous solution of copolymer 16)
10% by weight aqueous solution of Copolymer 8 with the exception that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 10 parts, 45 parts and 45 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 16 was obtained. The copolymer 16 had a weight average molecular weight of 50,000.

(Preparation of 10% by mass aqueous solution of copolymer 17)
10% by weight aqueous solution of Copolymer 9 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 10 parts, 45 parts and 45 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 17 was obtained. The copolymer 17 had a weight average molecular weight of 68,000.

(Preparation of 10 mass% aqueous solution of copolymer 18)
10 mass% aqueous solution of copolymer 6 except that the addition amount of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate was changed to 60 parts, 10 parts and 30 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 18 was obtained. The copolymer 18 had a weight average molecular weight of 3100.

(Preparation of 10 mass% aqueous solution of copolymer 19)
10% by weight aqueous solution of Copolymer 7 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 60 parts, 10 parts and 30 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 19 was obtained. The copolymer 19 had a weight average molecular weight of 4000.

(Preparation of 10% by mass aqueous solution of copolymer 20)
10% by weight aqueous solution of Copolymer 8 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 60 parts, 10 parts and 30 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 20 was obtained. The copolymer 20 had a weight average molecular weight of 48,000.

(Preparation of 10 mass% aqueous solution of copolymer 21)
10% by weight aqueous solution of Copolymer 9 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 60 parts, 10 parts and 30 parts, respectively. Similarly, a 10 mass% aqueous solution of copolymer 21 was obtained. The copolymer 21 had a weight average molecular weight of 70000.

(Preparation of 10 mass% aqueous solution of copolymer 22)
10 mass% aqueous solution of copolymer 6 except that the addition amount of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate was changed to 80 parts, 10 parts and 10 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 22 was obtained. The copolymer 22 had a weight average molecular weight of 3200.

(Preparation of 10 mass% aqueous solution of copolymer 23)
10% by weight aqueous solution of Copolymer 7 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 80 parts, 10 parts and 10 parts, respectively. Similarly, a 10 mass% aqueous solution of copolymer 23 was obtained. The copolymer 23 had a weight average molecular weight of 4200.

(Preparation of 10 mass% aqueous solution of copolymer 24)
10% by weight aqueous solution of Copolymer 8 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 80 parts, 10 parts and 10 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 24 was obtained. The copolymer 24 had a weight average molecular weight of 49000.

(Preparation of 10 mass% aqueous solution of copolymer 25)
10% by weight aqueous solution of Copolymer 9 except that the addition amounts of 1-methacryloyloxyethane-1,1-diphosphonic acid, diacetone acrylamide and oleyl acrylate were changed to 80 parts, 10 parts and 10 parts, respectively. Similarly, a 10% by mass aqueous solution of copolymer 25 was obtained. The copolymer 25 had a weight average molecular weight of 70000.

(Preparation of 10 mass% aqueous solution of copolymer 26)
A 10 mass% aqueous solution of copolymer 26 was obtained in the same manner as the 10 mass% aqueous solution of copolymer 1 except that potassium hydroxide was added so that the neutralization rate was 50%. The copolymer 26 had a weight average molecular weight of 3100.

(Preparation of 10 mass% aqueous solution of copolymer 27)
A 10% by mass aqueous solution of copolymer 27 was obtained in the same manner as the 10% by mass aqueous solution of copolymer 1 except that ethanolamine was used instead of potassium hydroxide. The copolymer 27 had a weight average molecular weight of 3100.

(Preparation of 10% by mass aqueous solution of homopolymer 1)
In a flask equipped with a stirrer, thermometer and nitrogen inlet tube, 500 parts of ethanol, chemical formula

で表される化合物（４−メタクリルアミド−１−ヒドロキシブタン−１，１−ジホスホン酸）１００部及び重合開始剤アゾビスイソブチロニトリル４部を仕込んだ後、７０℃まで昇温した。次に、窒素気流下、５時間重合した後、仕込んだエタノールの半量程度を留去した。さらに、アセトン中に投入した後、乾燥させ、単独重合体１の前駆体を得た。

Were charged with 100 parts of a compound represented by the formula (4-methacrylamide-1-hydroxybutane-1,1-diphosphonic acid) and 4 parts of a polymerization initiator azobisisobutyronitrile, and the temperature was raised to 70 ° C. Next, after polymerization for 5 hours in a nitrogen stream, about half of the charged ethanol was distilled off. Furthermore, after throwing in acetone, it was made to dry and the precursor of the homopolymer 1 was obtained.

  While diluting the precursor of the homopolymer 1 with water, potassium hydroxide was added so that the neutralization rate would be 100%, and then diluted with water to obtain a 10% by mass aqueous solution of the homopolymer 1. . The homopolymer 1 had a weight average molecular weight of 4100.

(Preparation of 10% by weight aqueous solution of Compound 1)
Chemical formula

で表される化合物（ヒドロキシエチリデンジホスホン酸）を水で希釈しながら、中和率が１００％になるように、水酸化カリウムを加えた後、水で希釈し、化合物１の１０質量％水溶液を得た。

While diluting the compound represented by the formula (hydroxyethylidene diphosphonic acid) with water, potassium hydroxide was added so that the neutralization rate would be 100%, and then diluted with water. Got.

<Weight average molecular weight of polymer>
Column thermostat CTO-20A (manufactured by Shimadzu Corp.), detector RID-10A (manufactured by Shimadzu Corp.), eluent channel pump LC-20AD (manufactured by Shimadzu Corp.), degasser DGU-20A (manufactured by Shimadzu Corp.) And the weight average molecular weight of the polymer was measured by GPC method using Autosampler SIL-20A (manufactured by Shimadzu Corporation). At this time, as the column, an aqueous SEC column TSKgel G3000PWXL (manufactured by Tosoh Corporation) with an exclusion limit molecular weight of 2 × 10 ^5, a TSKgel G5000PWXL (manufactured by Tosoh Corporation) with an exclusion limit molecular weight of 2.5 × 10 ⁶ , and an exclusion limit molecular weight of What connected 5 * 10 < ⁷ > TSKgelG6000PWXL (made by Tosoh Corporation) was used. Moreover, the solution which prepared the polymer to the density | concentration of 2 g / 100 mL with the eluent was used as a sample. Further, as an eluent, an aqueous solution in which acetic acid and sodium acetate were adjusted to a concentration of 0.5 mol / L was used. The column temperature was 40 ° C. and the flow rate was 1.0 mL / min. Furthermore, using 9 kinds of polyethylene glycols having molecular weights of 1065, 5050, 24000, 50000, 107000, 140000, 250,000, 540000, and 920,000 as standard samples, a calibration curve was obtained, and the weight of the polymer was determined based on the calibration curve. The average molecular weight was determined.

  Table 1 shows the characteristics of the copolymer.

（顔料分散体１の調製）
カーボンブラックＮＩＰＥＸ１５０（デグサ社製）２０部、固形分が１０質量％のナフタレンスルホン酸ホルマリン縮合物ナトリウム塩Ａ−４５−ＰＮ（竹本油脂社製）１３部及び純水６７部をプレミックスした後、ディスクタイプのビーズミルＫＤＬ型（シンマルエンタープライゼス社製）を用いて、周速１０ｍ／ｓで１０分間循環分散させた。このとき、メディアとして、直径が０．１ｍｍのジルコニアボールを使用した。次に、孔径が１．２μｍのメンブレンフィルターでろ過して、顔料分散体１を得た。

(Preparation of pigment dispersion 1)
After premixing 20 parts of carbon black NIPEX150 (manufactured by Degussa), 13 parts of naphthalenesulfonic acid formalin condensate sodium salt A-45-PN (manufactured by Takemoto Yushi Co.) having a solid content of 10% by mass and 67 parts of pure water, Using a disk-type bead mill KDL type (manufactured by Shinmaru Enterprises), it was circulated and dispersed for 10 minutes at a peripheral speed of 10 m / s. At this time, a zirconia ball having a diameter of 0.1 mm was used as a medium. Next, it was filtered through a membrane filter having a pore size of 1.2 μm to obtain Pigment Dispersion 1.

(Preparation of pigment dispersion 2)
20 parts of carbon black NIPEX150 (manufactured by Degussa), 50 parts of 10% by weight aqueous solution of copolymer 1 and 30 parts of pure water were premixed, and then a disk type bead mill KDL type (manufactured by Shinmaru Enterprises) was used. Circulated and dispersed for 10 minutes at a peripheral speed of 10 m / s. At this time, a zirconia ball having a diameter of 0.1 mm was used as a medium. Next, the mixture was filtered through a membrane filter having a pore size of 1.2 μm to obtain pigment dispersion 2.

(Preparation of pigment dispersion 3)
Pigment Dispersion 3 was obtained in the same manner as Pigment Dispersion 2 except that Pigment Blue 15: 3 Chromofine Blue (Daiichi Seika) was used instead of Carbon Black NIPEX150 (Degussa). .

(Preparation of pigment dispersion 4)
Pigment Dispersion 4 was obtained in the same manner as Pigment Dispersion 2, except that Pigment Red 122 Toner Magenta E02 (Clariant) was used instead of Carbon Black NIPEX150 (Degussa).

(Preparation of pigment dispersion 5)
Pigment Dispersion 5 was obtained in the same manner as Pigment Dispersion 2, except that Pigment Yellow First Yellow 531 (Daiichi Seika Co., Ltd.) was used instead of Carbon Black NIPEX150 (Degussa).

(Preparation of pigment dispersion 6)
A pigment dispersion 6 was obtained in the same manner as the pigment dispersion 2 except that a 10% by mass aqueous solution of the copolymer 2 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 7)
A pigment dispersion 7 was obtained in the same manner as the pigment dispersion 2 except that a 10 mass% aqueous solution of the copolymer 3 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 8)
A pigment dispersion 8 was obtained in the same manner as the pigment dispersion 2 except that a 10% by mass aqueous solution of the copolymer 4 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 9)
A pigment dispersion 9 was obtained in the same manner as the pigment dispersion 2 except that a 10 mass% aqueous solution of the copolymer 5 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 10)
Pigment dispersion 10 was obtained in the same manner as pigment dispersion 2, except that a 10% by mass aqueous solution of copolymer 26 was used instead of the 10% by mass aqueous solution of copolymer 1.

(Preparation of pigment dispersion 11)
A pigment dispersion 11 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 27 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 12)
A pigment dispersion 12 was obtained in the same manner as the pigment dispersion 2 except that a 10 mass% aqueous solution of the copolymer 6 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 13)
A pigment dispersion 13 was obtained in the same manner as the pigment dispersion 2 except that a 10% by mass aqueous solution of the copolymer 7 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 14)
A pigment dispersion 14 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 8 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 15)
A pigment dispersion 15 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 9 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 16)
A pigment dispersion 16 was obtained in the same manner as the pigment dispersion 2, except that a 10 mass% aqueous solution of the copolymer 10 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 17)
A pigment dispersion 17 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 11 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 18)
A pigment dispersion 18 was obtained in the same manner as the pigment dispersion 2, except that a 10 mass% aqueous solution of the copolymer 12 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 19)
A pigment dispersion 19 was obtained in the same manner as the pigment dispersion 2 except that a 10 mass% aqueous solution of the copolymer 13 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 20)
A pigment dispersion 20 was obtained in the same manner as the pigment dispersion 2 except that a 10% by mass aqueous solution of the copolymer 14 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 21)
A pigment dispersion 21 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 15 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 22)
A pigment dispersion 22 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 16 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 23)
A pigment dispersion 23 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 17 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 24)
A pigment dispersion 24 was obtained in the same manner as the pigment dispersion 2 except that a 10 mass% aqueous solution of the copolymer 18 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 25)
A pigment dispersion 25 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 19 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 26)
A pigment dispersion 26 was obtained in the same manner as the pigment dispersion 2 except that a 10% by mass aqueous solution of the copolymer 20 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 27)
A pigment dispersion 27 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 21 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 28)
A pigment dispersion 28 was obtained in the same manner as the pigment dispersion 2 except that a 10% by mass aqueous solution of the copolymer 22 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 29)
A pigment dispersion 29 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 23 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 30)
A pigment dispersion 30 was obtained in the same manner as the pigment dispersion 2 except that a 10 mass% aqueous solution of the copolymer 24 was used instead of the 10 mass% aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 31)
A pigment dispersion 31 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the copolymer 25 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 32)
A pigment dispersion 32 was obtained in the same manner as the pigment dispersion 2, except that a 10% by mass aqueous solution of the homopolymer 1 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Preparation of pigment dispersion 33)
A pigment dispersion 33 was obtained in the same manner as the pigment dispersion 2 except that a 10% by mass aqueous solution of the compound 1 was used instead of the 10% by mass aqueous solution of the copolymer 1.

  Next, the storage stability of the pigment dispersion was evaluated.

<Storage stability>
The pigment dispersion is put in a polyethylene container, sealed, and stored at 70 ° C. for 1 week, and the change rate [%] of the viscosity after storage with respect to the viscosity before storage is expressed by the formula | (viscosity of pigment dispersion after storage). − (Viscosity of pigment dispersion before storage) | / (viscosity of pigment dispersion before storage) × 100
And storage stability was evaluated. At this time, using a viscometer RE80L (manufactured by Toki Sangyo Co., Ltd.), the viscosity at 25 ° C. was measured by adjusting to 50 rotations or 100 rotations according to the viscosity of the sample. The viscosity change rate is less than 5%, A is 5% or more and less than 8%, B is 8% or more and less than 10%, C is 10% or more and less than 30%. The case where D was 30% or more was determined as E.

  Table 2 shows the evaluation results of the storage stability of the pigment dispersion.

（実施例１）
４０部の顔料分散体１、１，３−ブタンジオール２０部、グリセリン１０部、２−エチル−１，３−ヘキサンジオール１部、２，２，４−トリメチル−１，３−ペンタンジオール１部、固形分が４０質量％のフッ素系界面活性剤Ｚｏｎｙｌ ＦＳ−３００（ＤｕＰｏｎｔ社製）２部、共重合体１の１０質量％水溶液２０部及び純水６部を混合し、１．５時間撹拌した後、孔径が１．２μｍのメンブレンフィルターでろ過して、インクジェットインクを得た。

Example 1
40 parts pigment dispersion 1, 20 parts 1,3-butanediol, 10 parts glycerol, 1 part 2-ethyl-1,3-hexanediol, 1 part 2,2,4-trimethyl-1,3-pentanediol , 2 parts of a fluorosurfactant Zonyl FS-300 (manufactured by DuPont) having a solid content of 40% by mass, 20 parts of a 10% by mass aqueous solution of copolymer 1 and 6 parts of pure water were mixed and stirred for 1.5 hours. After that, the ink was filtered through a membrane filter having a pore size of 1.2 μm to obtain an inkjet ink.

(Example 2)
An inkjet ink was obtained in the same manner as in Example 1 except that a 10% by mass aqueous solution of copolymer 2 was used instead of the 10% by mass aqueous solution of copolymer 1.

(Example 3)
An inkjet ink was obtained in the same manner as in Example 1 except that a 10% by mass aqueous solution of copolymer 3 was used instead of the 10% by mass aqueous solution of copolymer 1.

Example 4
An inkjet ink was obtained in the same manner as in Example 1 except that a 10% by mass aqueous solution of the copolymer 4 was used instead of the 10% by mass aqueous solution of the copolymer 1.

(Example 5)
An inkjet ink was obtained in the same manner as in Example 1 except that a 10% by mass aqueous solution of copolymer 5 was used instead of the 10% by mass aqueous solution of copolymer 1.

(Example 6)
40 parts of pigment dispersion 2, 20 parts of 1,3-butanediol, 10 parts of glycerol, 1 part of 2-ethyl-1,3-hexanediol, 1 part of 2,2,4-trimethyl-1,3-pentazineol , 2 parts of a fluorosurfactant Zonyl FS-300 (manufactured by DuPont) having a solid content of 40% by mass and 26 parts of pure water were mixed, stirred for 1.5 hours, and then filtered with a membrane filter having a pore size of 1.2 μm. Filtration was performed to obtain an inkjet ink.

(Example 7)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 3 was used instead of the pigment dispersion 2.

(Example 8)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 4 was used instead of the pigment dispersion 2.

Example 9
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 5 was used instead of the pigment dispersion 2.

(Example 10)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 6 was used instead of the pigment dispersion 2.

(Example 11)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 7 was used instead of the pigment dispersion 2.

(Example 12)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 8 was used instead of the pigment dispersion 2.

(Example 13)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 9 was used instead of the pigment dispersion 2.

(Example 14)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 10 was used instead of the pigment dispersion 2.

(Example 15)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 11 was used instead of the pigment dispersion 2.

(Example 16)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 12 was used instead of the pigment dispersion 2.

(Example 17)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 13 was used instead of the pigment dispersion 2.

(Example 18)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 14 was used instead of the pigment dispersion 2.

(Example 19)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 15 was used instead of the pigment dispersion 2.

(Example 20)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 16 was used instead of the pigment dispersion 2.

(Example 21)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 17 was used instead of the pigment dispersion 2.

(Example 22)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 18 was used instead of the pigment dispersion 2.

(Example 23)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 19 was used instead of the pigment dispersion 2.

(Example 24)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 20 was used instead of the pigment dispersion 2.

(Example 25)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 21 was used instead of the pigment dispersion 2.

(Example 26)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 22 was used instead of the pigment dispersion 2.

(Example 27)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 23 was used instead of the pigment dispersion 2.

(Example 28)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 24 was used instead of the pigment dispersion 2.

(Example 29)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 25 was used instead of the pigment dispersion 2.

(Example 30)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 26 was used instead of the pigment dispersion 2.

(Example 31)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 27 was used instead of the pigment dispersion 2.

(Example 32)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 28 was used instead of the pigment dispersion 2.

(Example 33)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 29 was used instead of the pigment dispersion 2.

(Example 34)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 30 was used instead of the pigment dispersion 2.

(Example 35)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 31 was used instead of the pigment dispersion 2.

(Comparative Example 1)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 32 was used instead of the pigment dispersion 2.

(Comparative Example 2)
An inkjet ink was obtained in the same manner as in Example 6 except that the pigment dispersion 33 was used instead of the pigment dispersion 2.

  Next, the image density and storage stability of the inkjet ink were evaluated.

<Image density>
Inkjet printer IPSiO GX5000 (manufactured by Ricoh) was filled with inkjet ink in an environment of 23 ° C. and 50% RH. Next, a chart in which a general symbol of 64 points of JIS X 0208 (1997), 2223 created using Microsoft Word 2000 (manufactured by Microsoft) is described is used as an XEROX 4200 (XEROX 4200 X) containing about 16% by mass of calcium carbonate. (Hereinafter, referred to as plain paper 1) and MyPaper (hereinafter, referred to as plain paper 2) having a calcium carbonate content of about 4% by mass. Furthermore, using X-Rite 938 (manufactured by X-Rite Co., Ltd.), general symbols were color-measured to measure image density. At this time, a mode in which the “plain paper-standard fast” mode was changed to “no color correction” from the user setting for plain paper was used as a print mode.

  When black inkjet ink is used, the case where the image density is 1.25 or more is A, the case where it is 1.20 or more and less than 1.25 is B, the case where it is 1.10 or more and less than 1.20. The case where C was less than 1.10 was determined as D, and the case where the pigment was gelled and could not be dispersed in the inkjet ink and could not be printed was determined as E.

  When yellow inkjet ink is used, the case where the image density is 0.80 or more is A, the case where it is 0.75 or more and less than 0.80 is B, the case where it is 0.70 or more and less than 0.75. The case where C was less than 0.70 was determined as D, and the case where the pigment was gelled and could not be dispersed in the inkjet ink and could not be printed was determined as E.

  Further, when magenta inkjet ink is used, the case where the image density is 0.95 or more is A, the case where it is 0.85 or more and less than 0.95 is B, and the case where it is 0.75 or more and less than 0.85. The case where C was less than 0.75 was determined as D, and the case where the pigment was gelled and could not be dispersed in the inkjet ink and could not be printed was determined as E.

  Further, when cyan inkjet ink is used, the case where the image density is 1.05 or more is A, the case where it is 0.95 or more and less than 1.05 is B, and the case where it is 0.85 or more and less than 0.95. The case where C was less than 0.85 was determined as D, and the case where the pigment was gelled and could not be dispersed in the inkjet ink and could not be printed was determined as E.

<Storage stability>
After the ink cartridge is filled into the ink cartridge, it is stored at 70 ° C. for 1 week, and the change rate [%] of the viscosity after storage with respect to the viscosity before storage is expressed by the formula | (viscosity of inkjet ink after storage) − (before storage). Inkjet ink viscosity) | / (Inkjet ink viscosity before storage) × 100
And storage stability was evaluated. At this time, using a viscometer RE80L (manufactured by Toki Sangyo Co., Ltd.), the viscosity at 25 ° C. was measured by adjusting to 50 rotations or 100 rotations according to the viscosity of the sample. The viscosity change rate is less than 5%, A is 5% or more and less than 8%, B is 8% or more and less than 10%, C is 10% or more and less than 30%. The case where D was 30% or more was determined as E.

  Table 3 shows the evaluation results of the image density and storage stability of the inkjet ink.

表３から、実施例１〜３５のインクジェットインクは、普通紙における画像濃度及び保存安定性に優れることがわかる。

From Table 3, it can be seen that the inkjet inks of Examples 1 to 35 are excellent in image density and storage stability in plain paper.

  On the other hand, since the inkjet ink of Comparative Example 1 does not include the copolymer having the structural units represented by the general formulas (1) to (3) but includes the homopolymer 1, the storage stability is reduced. To do.

  Since the inkjet ink of Comparative Example 2 does not contain a copolymer having the structural units represented by the general formulas (1) to (3) and contains the compound 1, the image density and storage stability on plain paper are reduced. .

101 Device Main Body 134 Inkjet Head 142 Paper 200 Ink Cartridge

Special table 2009-513802

Claims (12)

Including water, water-soluble organic solvents, pigments and copolymers,
The copolymer has the general formula

(In the formula, R ₁ is a hydrogen atom or a methyl group, and M ₁ ⁺ , M ₂ ⁺ , M ₃ ⁺ and M ₄ ⁺ are each independently an alkali metal ion, an organic ammonium ion or a proton.)
And the general formula

(In the formula, R ₂ is a hydrogen atom or a methyl group.)
And the general formula

(In the formula, R ₃ is a hydrogen atom or a methyl group.)
An inkjet ink comprising a structural unit represented by:   2. The inkjet ink according to claim 1, wherein the copolymer has a content of the structural unit represented by the general formula (1) of 10% by mass or more and 60% by mass or less. Including water, water-soluble organic solvents, pigments and copolymers,
The copolymer has the general formula

(In the formula, R ₁ is a hydrogen atom or a methyl group.)
And a compound represented by the general formula

(In the formula, R ₂ is a hydrogen atom or a methyl group.)
And a compound represented by the general formula

(In the formula, R ₃ is a hydrogen atom or a methyl group.)
An ink-jet ink synthesized by copolymerizing a monomer containing a compound represented by the formula:   4. The inkjet ink according to claim 1, wherein the copolymer has a weight average molecular weight of 4,000 to 50,000. The inkjet ink according to claim 1, wherein R ₁ is a methyl group. The inkjet ink according to claim 1, wherein R ₂ is a hydrogen atom. The inkjet ink according to claim 1, wherein R ₃ is a hydrogen atom.   The inkjet ink according to any one of claims 1 to 7, wherein the alkali metal ion is a potassium ion. A method for producing an ink-jet ink according to any one of claims 1 to 8,
Preparing a pigment dispersion in which the pigment is dispersed in water,
The method for producing an ink-jet ink, wherein the pigment dispersion contains the copolymer.   An ink cartridge containing the ink-jet ink according to any one of claims 1 to 8.   An ink jet recording apparatus, comprising: an ejection unit that ejects the ink jet ink according to claim 1.   A recorded matter, wherein an image is recorded with the inkjet ink according to claim 1.

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