JP2012102247A - Inkjet recording ink, ink cartridge, and inkjet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording ink which ensures improvement in plugging of an inkjet head and is superior in discharge stability and storage stability while obtaining high image density even in recording on plain paper, and to provide an ink cartridge and an inkjet recording apparatus using the inkjet recording ink.SOLUTION: The inkjet recording ink contains at least a colorant, a water-soluble organic solvent, water, and an alkali dispersible alumina sol. It is preferable that the colloidal particle in the alkali dispersible alumina sol has an average particle diameter of 5-300 nm, and the content of the alkali dispersible alumina sol is 1-10 mass% as the solid content of the colloidal particle.

Description

  The present invention relates to an ink for ink jet recording, an ink cartridge using the ink for ink jet recording, and an ink jet recording apparatus.

The pigment ink used for inkjet recording is generally prepared by preparing a dispersion in which a pigment and a dispersant as a colorant are pre-dispersed in an aqueous solvent such as water and alcohol, and then dispersing the dispersion into a media such as a sand mill. It is prepared by performing a dispersion step of dispersing to a predetermined degree using a mold disperser and then diluting to a predetermined concentration.
In water-based inks using pigments as colorants, it is common to use dispersants such as surfactants and water-soluble resins in order to disperse hydrophobic pigments, but the problem is that the reliability of the resulting image is extremely poor There is. Therefore, a technique for adding film-forming resin fine particles to ink for the purpose of improving image quality is known. However, it is difficult to finely and stably disperse a plurality of components over a long period of time. If a large amount of a dispersant such as a surfactant is used to stably disperse these fine particles, bubbles in the ink tank or head Problems such as generation and degradation of image quality occur.
In addition, for the purpose of improving dispersibility, a method of changing the surface of the pigment to a hydrophilic group, a method using a resin containing a hydrophilic group, and the like have been studied. When different types are mixed, there is a problem that dispersion becomes unstable and storage stability deteriorates. In addition to this, various means for improving the dispersibility have been proposed, but no means that can sufficiently satisfy high image density and storage stability has yet been provided.

A pigment dispersion using carbon black as a pigment and a sodium naphthalene sulfonate formalin condensate as a dispersant and an ink using the pigment dispersion have been proposed (see Patent Document 1). However, the proposed ink has an insufficient image density when recorded on plain paper, and the storage stability of the ink is not satisfactory.
In addition, an ink containing an anionic self-emulsifying ether-based polyurethane resin emulsion at the time of ink preparation using sodium naphthalenesulfonate formalin condensate as a dispersant for the carbon black dispersion has been proposed (see Patent Documents 2 and 3). . However, although these proposed inks have improved storage stability, the image density when recorded on plain paper is insufficient.
In addition, in order to improve the image density when recorded on plain paper, an aqueous ink-jet ink in which colloidal silica is contained in the ink has been proposed (see Patent Document 4). However, the ink with a small surface tension as in this proposal has a small effect of improving the image density when recorded on plain paper.
Further, a recording method and a recording apparatus for recording on a recording medium using an ink containing a color material and a liquid composition containing fine particles that react with the color material in the ink and not containing the color material have been proposed. (See Patent Documents 5 and 6). However, although these proposals exemplify alumina sol as the fine particles, these are all alumina fine particles whose dispersion state is stable in the acidic pH region. In addition to the ink containing the color material, a liquid composition not containing the color material is required, so that the recording apparatus becomes complicated.

  Therefore, even when recording on plain paper, a high image density is obtained, the clogging of the ink jet head is improved, and the ink for ink jet recording excellent in ejection stability and storage stability, and the ink for ink jet recording are used. Under the present circumstances, it is desired to promptly provide ink cartridges and ink jet recording apparatuses.

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention can provide a high image density even when recording on plain paper, improve the clogging of the inkjet head, improve the ejection stability and storage stability, and the inkjet recording ink. An object of the present invention is to provide an ink cartridge and an ink jet recording apparatus using the ink for use.

Means for solving the problems are as follows. That is,
<1> An inkjet recording ink comprising at least a colorant, a water-soluble organic solvent, water, and an alkali-dispersible alumina sol.
<2> The inkjet recording ink according to <1>, wherein the colloidal particles in the alkali-dispersible alumina sol have an average particle diameter of 5 nm to 300 nm.
<3> The inkjet recording ink according to any one of <1> to <2>, wherein the content of the alkali-dispersible alumina sol is 1% by mass to 10% by mass as the solid content of the colloidal particles.
<4> An ink cartridge, wherein the ink for ink jet recording according to any one of <1> to <3> is contained in a container.
<5> An inkjet recording apparatus comprising an ejection unit that ejects the inkjet recording ink according to any one of <1> to <3> to form an image.

  According to the present invention, the conventional problems can be solved and the object can be achieved, and even when recording on plain paper, a high image density can be obtained, the clogging of the inkjet head is improved, and the ejection stability is improved. Ink jet recording ink excellent in stability and storage stability, an ink cartridge using the ink jet recording ink, and an ink jet recording apparatus can be provided.

FIG. 1 is a perspective view showing an example of the ink jet recording apparatus of the present invention.

(Inkjet recording ink)
The ink for inkjet recording of the present invention contains at least a colorant, a water-soluble organic solvent, water, and an alkali-dispersible alumina sol, and further contains other components as necessary.

<Colorant>
The colorant is preferably a pigment. As the pigment, an organic pigment or an inorganic pigment can be used. In addition, although you may contain dye simultaneously for the purpose of color tone adjustment, it is possible to use within the range which does not degrade a weather resistance.
Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is particularly preferable.
In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

Examples of the organic pigment include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable.
Examples of the azo pigment include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments.
Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofullerone pigments.
Examples of the dye chelates include basic dye chelates and acidic dye chelates.

There is no restriction | limiting in particular as a color of the said coloring agent, According to the objective, it can select suitably, For example, the thing for black, the thing for color, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
Examples of the black color include carbon black (CI pigment black 7), copper, iron (CI pigment black 11), metals such as titanium oxide, aniline black (CI pigment black). And organic pigments such as 1).
As the carbon black, any of channel black, gas black and furnace black is preferable.
The average primary particle diameter of the carbon black is preferably 10.0 nm to 30.0 nm, and more preferably 15.0 nm to 20.0 nm.
BET specific surface area of the carbon black ^is preferably 100m ² / g~400m 2 / ^g, is preferably 150m ² / g~300m 2 / g.
Here, the average primary particle diameter of the carbon black can be calculated from the particle diameter and the number of the photographed image obtained by, for example, photographing particles using an electron micrograph. The BET specific surface area of the carbon black can be measured by a BET method based on nitrogen adsorption.

  Examples of the color are C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 408, 109, 110, 117, 120, 128, 138, 150, 151, 153, 183; I. Pigment orange 5, 13, 16, 17, 36, 43, 51; C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219; I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38; I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 16, 17: 1, 56, 60, 63; I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

-Self-dispersing pigment-
In the present invention, a self-dispersing pigment may be used as the colorant. The self-dispersing pigment means a surface modified so that at least one hydrophilic group is bonded to the surface of the pigment directly or through another atomic group.
In the surface modification, a specific functional group (a functional group such as a sulfone group or a carboxyl group) is chemically bonded to the surface of the pigment, or at least one of hypohalous acid and a salt thereof is used. A method such as wet oxidation is used. Among these, a form in which a carboxyl group is bonded to the surface of the pigment and dispersed in water is particularly preferable.
In this way, the surface of the pigment is modified and the carboxyl group is bonded, so not only the dispersion stability is improved, but also high-quality print quality is obtained and the water resistance of the recording medium after printing is further improved. To do.
In addition, since this form of ink has excellent redispersibility after drying, printing is paused for a long period of time, and clogging does not occur even when the ink moisture near the nozzles of the inkjet head evaporates, making it easy with a simple cleaning operation. Can print well.
The volume average particle diameter of the self-dispersing pigment is preferably 0.01 μm to 0.16 μm in the ink jet recording ink.
For example, as the self-dispersing carbon black, those having ionicity are preferable, and those having an anionic charge or those charged in a cationic form are suitable.
Examples of the anionic hydrophilic group include —COOM, —SO ₃ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NH ₂ , —SO ₂ NHCOR (where M is a hydrogen atom, an alkali metal) R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent.
Among these, it is particularly preferable to use those in which —COOM and —SO ₃ M are bonded to the color pigment surface.

Further, “M” in the hydrophilic group includes, for example, lithium, sodium, potassium and the like as an alkali metal.
Examples of the organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, and mono to trimethanol ammonium.
As a method of obtaining the anionically charged color pigment, as a method of introducing —COONa to the color pigment surface, for example, a method of oxidizing the color pigment with sodium hypochlorite, a method of sulfonation, a diazonium salt The method of making it react is mentioned.

  As the cationic hydrophilic group, for example, a quaternary ammonium group is preferable, and a quaternary ammonium group is more preferable. In the present invention, any of these bonded to the carbon black surface is suitable as a coloring material. It is.

  There is no restriction | limiting in particular as a method of manufacturing the cationic self-dispersion type carbon black to which the said hydrophilic group was couple | bonded, According to the objective, it can select suitably, For example, as a method of couple | bonding N-ethyl pyridyl group And a method of treating carbon black with 3-amino-N-ethylpyridinium bromide.

The hydrophilic group may be bonded to the surface of the carbon black through another atomic group. Examples of other atomic groups include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent.
Specific examples of the case where the hydrophilic group is bonded to the surface of carbon black through another atomic group include, for example, —C ₂ H ₄ COOM (where M represents an alkali metal or quaternary ammonium). , -PhSO ₃ M (however, .M Ph is the phenyl group represents an alkali metal or quaternary _{ammonium), - C 5 H 10 NH} 3 + , and the like.

Moreover, the composite pigment which coat | covered the general organic pigment or the inorganic pigment particle | grain with the organic pigment or carbon black can be used conveniently.
The composite pigment can be produced by a method of depositing an organic pigment in the presence of inorganic pigment particles, a mechanochemical method of mechanically mixing and grinding an inorganic pigment and an organic pigment, or the like.
Further, if necessary, an adhesive layer between the inorganic pigment and the organic pigment can be improved by providing a layer of an organosilane compound formed from polysiloxane and alkylsilane between the inorganic pigment and the organic pigment.
Examples of the organic pigment include aniline black as a black pigment. Examples of color pigments include anthraquinone, phthalocyanine blue, phthalocyanine green, diazo, monoazo, pyranthrone, perylene, heterocyclic yellow, quinacridone, and (thio) indigoid.
Among these, carbon black, phthalocyanine pigments, quinacridone pigments, monoazo yellow pigments, disazo yellow pigments, and heterocyclic yellow pigments are particularly preferable in terms of color developability.

Examples of the phthalocyanine blue include copper phthalocyanine blue or a derivative thereof (CI pigment blue 15: 3, 15: 4), aluminum phthalocyanine, and the like.
Examples of the quinacridone include C.I. I. Pigment orange 48, C.I. I. Pigment orange 49, C.I. I. Pigment red 122, C.I. I. Pigment red 192, C.I. I. Pigment red 202, C.I. I. Pigment red 206, C.I. I. Pigment red 207, C.I. I. Pigment red 209, C.I. I. Pigment violet 19, C.I. I. Pigment violet 42, and the like.
Examples of the monoazo yellow include C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 151.
Examples of the disazo yellow include C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17 and the like.
Examples of the heterocyclic yellow include pigment yellow 117 and pigment yellow 138.
Other color pigments are described in The Color Index, Third Edition (The Society of Dyer's and Colorists, 1982).

Examples of the inorganic pigment include titanium dioxide, silica, alumina, iron oxide, iron hydroxide, and tin oxide. The particle shape preferably has a small aspect ratio, and is most preferably spherical.
The color of the inorganic pigment is preferably transparent or white when the color material is adsorbed on the surface. However, when the black color material is adsorbed on the surface, a black inorganic pigment is used. It doesn't matter.
The primary particle diameter of the inorganic pigment particles is preferably 100 nm or less, and more preferably 5 nm to 50 nm.
The mass ratio of the inorganic pigment particles to the organic pigment or carbon black as the color material is preferably 3: 1 to 1: 3, and more preferably 3: 2 to 1: 2.
When the amount of the coloring material is small, the color developability and coloring power may be lowered, and when the amount of the coloring material is large, the transparency and the color tone may be deteriorated.
Color material particles obtained by coating such inorganic pigment particles with an organic pigment or carbon black include silica / carbon black composite material manufactured by Toda Kogyo Co., Ltd., silica / phthalocyanine PB15: 3 composite material, silica / disazo yellow composite material, Since silica / quinacridone PR122 composite material has a small primary average particle size, it can be suitably used.
Here, when inorganic pigment particles having a primary particle size of 20 nm are coated with an equal amount of organic pigment, the primary particle size of this pigment is about 25 nm.
If a primary dispersant can be dispersed using a suitable dispersant for this, a very fine pigment-dispersed ink having a dispersed particle diameter of 25 nm can be produced.
In the composite pigment, not only the organic pigment on the surface contributes to the dispersion, but also the properties of the inorganic pigment at the center appear through the thin layer of the organic pigment having a thickness of about 2.5 nm. The selection of the pigment dispersant is also important.

-Polymer fine particles containing polymer fine particles containing water-insoluble or poorly water-soluble color material (aqueous dispersion of polymer fine particles containing color material)-
As the colorant, a polymer emulsion type pigment in which a polymer fine particle contains a water-insoluble or hardly water-soluble coloring material, or a microcapsule type pigment in which a pigment is coated with a resin having a hydrophilic group may be used.
In polymer emulsion type pigments in which water-insoluble or poorly water-soluble coloring material is contained in the polymer fine particles, the polymer emulsion containing the coloring material is a polymer fine particle encapsulated with a pigment and a pigment on the surface of the polymer fine particle. It means at least one of those adsorbed. For example, what was described in Unexamined-Japanese-Patent No. 2001-139849 etc. are mentioned.
In this case, it is not necessary for all the pigments to be enclosed or adsorbed in the polymer fine particles, and the pigments may be dispersed in the emulsion as long as the effects of the present invention are not impaired.
The “water-insoluble or hardly water-soluble” means that the coloring material does not dissolve 10 parts by mass or more with respect to 100 parts by mass of water at 20 ° C. The term “dissolves” means that separation or sedimentation of the coloring material is not observed on the surface layer or lower layer of the aqueous solution.

The polymer that forms the polymer emulsion is not particularly limited and may be appropriately selected depending on the intended purpose. For example, vinyl polymers, polyester polymers, polyurethane polymers, JP 2000-53897 A, JP The polymer etc. which are indicated by 2001-139849 gazette are mentioned. Among these, vinyl polymers and polyester polymers are particularly preferable.
The volume average particle diameter of the polymer fine particles (colored fine particles) containing the coloring material is preferably 0.01 μm to 0.16 μm in the ink.
When a polymer emulsion type pigment is used, an ink excellent in light resistance and fixability can be obtained.
A microcapsule-type pigment coated with a pigment having a hydrophilic group is a pigment dispersed in water by coating the pigment with a hydrophilic and water-insoluble resin and hydrophilizing the resin layer on the pigment surface. For example, those described in JP-A-2002-67473 can be mentioned, and an ink excellent in light resistance and fixability can be obtained.

Of the colorants, those that are not dispersion-stabilized are preferably blended into the ink after preparing a colorant dispersion (pigment dispersion) using an appropriate dispersant.
As the dispersant, for example, an anionic active agent, a nonionic active agent, a cationic active agent, and an amphoteric active agent can be used.

  Examples of the anionic activator include fatty acid salts, alkyl sulfate esters, alkylaryl sulfonates, alkylnaphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, and alkyl phosphates. , Polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl aryl ether sulfate, naphthalenesulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, polyoxyethylene glycerol fatty acid ester, etc. It is done.

  Examples of the nonionic activator include polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin. Examples thereof include fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, fluorine-based and silicone-based nonionic active agents.

Examples of the cationic activator include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, alkylimidazolium salts, and the like.
Examples of the amphoteric activators include alkylbetaines, alkylamine oxides, phosphadylcholines, and the like.

The pigment dispersion can be obtained by wet-dispersing a coloring agent, a dispersing agent, water, and various additives as necessary using a known dispersing machine such as a sand mill, a ball mill, a roll mill, a bead mill, a nanomizer, or a homogenizer. it can.
Here, the wet dispersion treatment is a treatment in which a mixture of carbon black, a dispersant, water, and a water-soluble organic solvent added as necessary is finely pulverized and dispersed by a so-called wet dispersion method. Means that.

  The content of the colorant is preferably 1% by mass to 20% by mass and more preferably 3% by mass to 15% by mass with respect to the total amount of the ink jet recording ink. If the content of the colorant is 1% by mass or more, the image density is not too low and the printed image is not sharp. If the content of the colorant is 20% by mass or less, Ink viscosity does not become too high, and nozzle clogging does not easily occur.

<Water-soluble organic solvent>
There is no restriction | limiting in particular as said water-soluble organic solvent, Although it can select suitably according to the objective, A thing with a boiling point of 180 degreeC or more is preferable. When the water-soluble organic solvent is contained in the ink for ink-jet recording, the water retention and wettability of the ink can be ensured. There is no increase in viscosity, and excellent storage stability can be realized. Also, an ink for ink jet recording can be realized that maintains the fluidity of the dried material for a long time even when left open at the nozzle tip of an ink jet printer. Furthermore, nozzle clogging does not occur during printing or when restarting after printing interruption, and high ejection stability can be obtained.

  Examples of the water-soluble organic solvent include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, and carbonic acid. Examples include ethylene. These may be used alone or in combination of two or more.

Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, Examples include tetraethylene glycol, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, and petriol.
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol mono Examples include butyl ether, triethylene glycol isobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monobutyl ether.
Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam.
Examples of the amides include formamide, N-methylformamide, N, N-dimethylformamide and the like.
Examples of the amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol, thiodiglycol and the like.
Among these, glycerin, 2-pyrrolidone, diethylene glycol, thiodiethanol, polyethylene glycol, triethylene glycol, tetraethylene glycol, 1,2,6-hexanetriol, 1,2,4- from the viewpoint of ink ejection stability. Preferred are butanetriol, petriol, 1,5-pentanediol, 1,6-hexanediol, N-methyl-2-pyrrolidone, 1,3-butanediol, and 3-methyl-1,3-butanediol. Among these, glycerin, 3-methyl-1,3-butanediol, 2-pyrrolidone, 1,5-pentanediol, and 1,6-hexanediol are particularly preferable.

  The content of the water-soluble organic solvent is preferably 50% by mass or less, more preferably 5% by mass to 40% by mass, and still more preferably 10% by mass to 35% by mass with respect to the total amount of the ink for inkjet recording.

<Alkali dispersible alumina sol>
Various types of alumina sol have been known. For example, JP-A-59-78925 discloses an acidic alumina sol composed of pseudoboehmite crystals, and JP-A-53-112299 discloses an acidic alumina sol having a boehmite crystal lattice. .
These sols are actually alumina hydrate sols, but are conventionally called alumina sols.

  The above conventional alumina sol is an acidic (cationic) alumina sol, and usually contains an inorganic acid or an organic acid as a particle stabilizer. There was a problem. In addition, these acidic alumina sols cannot be used in water-based ink for ink-jet recording because they cause aggregation when mixed with anionic fine particles such as colorants in water-based ink for ink-jet recording.

  The alumina sol used in the present invention is an alkali-dispersible alumina sol. Strictly speaking, it is an alumina hydrate (aluminum hydroxide) sol having excellent dispersion stability in the alkali region.

Since the alumina hydrate fine particles constituting the alkali-dispersible alumina sol used in the present invention are negatively charged, aggregation does not occur even when mixed with anionic fine particles such as a colorant. Since the pH of a general ink for ink jet recording is about 8 to 10, the alumina hydrate fine particles are stably dispersed in the ink. On the other hand, the alkali-dispersible alumina sol has a characteristic that dispersion stability is lost in a neutral region or an acidic region (when the pH is lowered), and thickening / aggregation easily occurs.
In general, widely used plain paper has a surface pH ranging from acidic to neutral. When ink is printed and recorded on plain paper by an inkjet recording device, the pH of the ink is lowered due to the constituents of plain paper, so the balance of the dispersion state of the alumina sol in the ink is lost and thickening and aggregation occur. .
At this time, the pigment as the colorant is easily trapped on the network structure of plain paper. For this reason, a large amount of pigment is present near the surface of plain paper, and it is estimated that the image density is increased.
Examples of the method for producing the alkali-dispersible alumina sol used in the present invention include an acidic alumina hydrate sol containing cationic alumina hydrate fine particles composed of single or plural crystals, and the presence of alkali in the aqueous phase. Below, the method of making it contact with an anion exchanger can be mentioned.
Examples of the fine particles of alumina hydrate include boehmite, pseudoboehmite, gypsite, diaspore, bayerite, and amorphous alumina hydrate. Alumina composed of single or plural crystals selected from these. One or a combination of two or more are used as a dispersoid.

By the above-mentioned method, an alkaline alumina hydrate sol having a low viscosity and stable in an alkaline region of pH 9 to 13 can be obtained.
As another method for producing an alkali-dispersible alumina sol, alumina trihydrate is calcined to produce alumina monohydrate, and even if the alumina monohydrate is water, it is kneaded (milled) with the dispersion. A method for producing a colloidal dispersion of particles having an average particle size of less than 1 μm can be mentioned. The calcination temperature is generally 300 ° C to 750 ° C. The alumina trihydrate may be calcined at a temperature on the order of 400 ° C. and cooled to substantially ambient temperature prior to kneading. The alumina monohydrate may be quenched with cold water immediately after calcination. The sol medium should be alkaline in order to produce a stable anionic sol, and an alkali such as sodium hydroxide can be added to the medium for this purpose. However, when alumina trihydrate is obtained from bauxside by the Bayer method, sufficient residual alkali is present in the alumina trihydrate, so that it is not particularly necessary to add alkali.

The average particle size of the colloidal particles of the alkali-dispersible alumina sol in the present invention is preferably 5 nm to 300 nm, and more preferably 10 nm to 200 nm with a fine particle size and a uniform particle size distribution.
The alkali-dispersible alumina sol may be used in combination of two or more colloidal particles having different average particle diameters.
The content of the alkali-dispersible alumina sol in the ink is preferably 1% by mass to 10% by mass and more preferably 2% by mass to 7% by mass as the solid content of the colloidal particles. When the content is less than 1% by mass, the effect of improving the image density may be difficult to obtain. When the content is more than 10% by mass, it is difficult to obtain an ink having good storage stability and ejection stability. is there.

<Water>
There is no restriction | limiting in particular as said water, According to the objective, it can select suitably, For example, using pure water, such as ion-exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water is used. it can.

<Other ingredients>
Examples of the other components include penetrants, surfactants, water-dispersible resin particles, water-soluble polymers, antifoaming agents, antiseptic / antifungal agents, rust preventives, pH adjusters, specific resistance adjusters, and antioxidants. Agents, ultraviolet absorbers, oxygen absorbers, light stabilizers, viscosity modifiers and the like.

-Penetration agent-
Examples of the penetrant include 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-2-methyl-1,3-propanediol, 3 , 3-dimethyl-1,2-butanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4- Examples include pentanediol, 2,5-dimethyl-2,5-hexanediol, and 5-hexene-1,2-diol. Among these, 2-ethyl-1,3-hexanediol is particularly preferable.
The content of the penetrant is preferably 0.1% by mass to 4.0% by mass with respect to the total amount of the ink for inkjet recording.

-Surfactant-
Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

-Water-dispersible resin particles-
The water dispersible resin particles may be blended in order to further improve the scratch resistance of the image.
The water-dispersible resin particles mean a resin emulsion in which the continuous phase is water and the dispersed phase is a resin component. Examples of the resin component of the dispersed phase include acrylic resins, vinyl acetate resins, styrene-butadiene resins, polyurethane resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, styrene resins, and the like. .

-Water-soluble polymer-
The water-soluble polymer may be blended in order to further improve the dispersion stability of the ink.
As the water-soluble polymer, for example, a water-soluble polyurethane compound is preferable.

  The ink for inkjet recording of the present invention can be produced by a known method without any particular limitation. For example, a colorant, a water-soluble organic solvent, water, an alkali-dispersible alumina sol, and other components as necessary are stirred. It is obtained by mixing while filtering, filtering coarse particles with a filter, a centrifugal separator or the like, and deaeration as necessary.

  The ink for ink jet recording of the present invention can be suitably used for an ink cartridge that contains the ink as described later. Further, as will be described later, an image can be formed by an ink jet recording apparatus in which the ink for ink jet recording of the present invention is ejected onto a recording medium such as paper.

(ink cartridge)
The ink cartridge of the present invention is one in which the ink for ink jet recording of the present invention is contained in a container. There is no restriction | limiting in particular as said container, The shape, a structure, a magnitude | size, a material, etc. can be suitably selected according to the objective, For example, it has an ink bag etc. which were formed with the aluminum laminate film, the resin film, etc. Preferably, a plastic case or the like is used.

(Inkjet recording device)
The ink jet recording apparatus of the present invention has discharge means for forming an image by discharging the ink for ink jet recording of the present invention, and further has other means as necessary.
As a method of printing (discharging), a continuous jet type or an on-demand type can be mentioned. Examples of the on-demand type include a piezo method, a thermal method, and an electrostatic method.

Here, the ink cartridge and the ink jet recording apparatus of the present invention will be described with reference to FIG.
In FIG. 1, an ink cartridge 20 that accommodates an ink jet recording ink of the present invention is accommodated in a carriage 18. Here, a plurality of ink cartridges 20 are provided for convenience, but it is not necessary to have a plurality. In such a state, the ink for ink jet recording is supplied from the ink cartridge 20 to the droplet discharge head 18 a mounted on the carriage 18. In FIG. 1, the discharge nozzle surface is in an invisible state because it faces downward, but ink jet recording ink is discharged from this discharge nozzle.
The droplet discharge head 18 a mounted on the carriage 18 is guided and moved by the guide shafts 21 and 22 by the timing belt 23 driven by the main scanning motor 26.
On the other hand, a specific coated paper (recording medium) is placed at a position facing the droplet discharge head 18 a by the platen 19. In FIG. 1, 1 is an ink jet recording apparatus, 2 is a main body housing, 16 is a gear mechanism, 17 is a sub-scanning motor, and 25 is a gear mechanism.

When an image is formed on a recording medium using the inkjet recording apparatus containing the inkjet recording ink or ink cartridge of the present invention, an image forming body printed on the recording medium on demand is obtained. Further, the replenishment of ink for ink jet recording can be replaced in units of ink cartridges.
There is no restriction | limiting in particular as said recording medium, According to the objective, it can select suitably, For example, a plain paper, glossy paper, special paper, cloth, a film, an OHP sheet etc. are mentioned. Among these, paper is particularly preferable.

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

(Production Example 1)
<Preparation of Alkali Dispersible Alumina Sol 1>
Acidic alumina sol (Catalyst Chemical Industries, Ltd., Cataloid AS-1, solid content concentration: 7.5% by mass, average particle size: 10 nm, main crystal form: boehmite type, acetic acid content: 3% by mass, pH: 4. 3) After stirring 1,000 g of pure water and 1,940 g of pure water at room temperature, 1,000 mL of strongly basic anion exchange resin (manufactured by Mitsubishi Kasei Co., Ltd., DIAION, SA-10A) was gradually added. After adding 60 g of 1% by mass sodium hydroxide and stirring for 20 hours, the ion exchange resin was removed to obtain an aqueous alkaline alumina colloidal solution.
The obtained alkaline colloidal aqueous solution was concentrated to obtain a 20% by mass colloidal aqueous solution as a solid content. The pH of the aqueous colloidal solution was 9.6. The average particle size of the colloidal particles dispersed in the aqueous alumina colloidal solution was measured at 23 nm and 55% RH using a particle size distribution meter (Microtrac UPA-150EX, manufactured by Nikkiso Co., Ltd.). there were. The crystal form of the colloidal particles was boehmite and was not different from the crystal form before the treatment.

(Production Example 2)
<Preparation of Alkali Dispersible Alumina Sol 2>
Acidic alumina sol (catalyst chemical industry make, Cataloid AS-2, solid content concentration: 10% by mass, average particle size: 40 nm, main crystal form: boehmite type, hydrochloric acid content: 0.3% by mass, pH: 3. 4) While stirring 500 g and pure water 1,450 g at 40 ° C., 500 mL of strongly basic anion exchange resin (manufactured by Mitsubishi Kasei Co., Ltd., DAIAION, SA-10A) was gradually added thereto, and then 1 mass. % Lithium hydroxide 50 g was added and stirred for 18 hours.
Subsequently, after cooling to room temperature, the ion exchange resin was removed to obtain an aqueous alkaline alumina colloid solution.
The obtained colloidal aqueous solution was concentrated to obtain a 25% by mass colloidal aqueous solution as a solid content. The pH of the aqueous colloidal solution was 9.4. The average particle size of the colloidal particles dispersed in this alumina colloidal aqueous solution was 40 nm when measured in an environment of 23 ° C. and 55% RH using a particle size distribution meter (Microtrac UPA-150EX, manufactured by Nikkiso Co., Ltd.). there were. The crystal form of the colloidal particles was boehmite and was not different from the crystal form before the treatment.

(Production Example 3)
<Preparation of alkali dispersible alumina sol 3>
Acidic alumina sol (catalyst chemical industry make, Cataloid AS-3, solid content concentration: 10% by mass, average particle size: 200 nm, main crystal form: boehmite type, acetic acid content: 0.4% by mass, pH: 6. 9) While stirring 500 g of pure water and 85 g of pure water at room temperature, 350 mL of a strongly basic anion exchange resin (manufactured by Mitsubishi Kasei Co., Ltd., DAIAION, SA-10A) was gradually added thereto, and then 1 mass% tetramethyl. After 40 g of ammonium hydroxide was added and stirring was continued for 20 hours, the ion exchange resin was removed to obtain an aqueous alkaline alumina colloidal solution.
The obtained colloidal aqueous solution was concentrated to obtain a 20% by mass colloidal aqueous solution as a solid content. The pH of the aqueous colloidal solution was 9.1. The average particle size of the colloidal particles dispersed in this alumina colloidal aqueous solution was 180 nm when measured in a 23 ° C. and 55% RH environment using a particle size distribution meter (Microtrac UPA-150EX, manufactured by Nikkiso Co., Ltd.). there were. The crystal form of the colloidal particles was boehmite and was not different from the crystal form before the treatment.

(Synthesis Example 1)
-Synthesis of silicone-modified acrylic resin fine particles containing no reactive silyl groups-
After sufficiently replacing the inside of the flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube, and dropping funnel with nitrogen gas, 10 g of Aqualon RN-20 (Daiichi Kogyo Seiyaku Co., Ltd.), persulfuric acid 1 g of potassium and 286 g of pure water were charged, and the temperature was raised to 65 ° C. Next, 150 g of methyl methacrylate, 100 g of 2-ethylhexyl acrylate, 20 g of acrylic acid, 20 g of vinyltriethoxysilane, 10 g of Aqualon RN-20 (Daiichi Kogyo Seiyaku Co., Ltd.), 4 g of potassium persulfate, and pure water 398. 3 g of the mixed solution was dropped into the flask over 2.5 hours. The mixture was further heated and aged at 80 ° C. for 3 hours and then cooled, and adjusted with potassium hydroxide to have a pH of 7 to 8 and a solid concentration of 30% by mass.

Example 1
<Preparation of pigment dispersion (A)>
Carbon black (NIPEX 160-IQ, manufactured by degussa, gas black, BET specific surface area 150 m ² / g): 170 parts by mass Styrene-maleic acid copolymer resin (Regit SM101, manufactured by Sanyo Chemical Industries, Ltd.)・ ・ 9 parts by mass ・ Sodium hydroxide: 2 parts by mass ・ Pure water: 819 parts by mass After pre-dispersing the above mixture with a ball mill using zirconia beads having a diameter of 3 mm, a disk-type bead mill (Shinmaru Enterprise) After the dispersion at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. for 5 minutes using a zirconia bead having a diameter of 0.3 mm, a centrifuge (Model 3600 manufactured by Kubota Corporation) was used. ) And coarse particles were centrifuged to prepare a pigment dispersion (A).

<Preparation of inkjet recording ink a>
Using the obtained pigment dispersion (A), an ink solution was prepared according to the following formulation, stirred for 30 minutes, filtered through a membrane filter having a pore size of 0.8 μm, vacuum degassed, and ink jet recording of Example 1 Ink a was prepared.
[Ink prescription]
Pigment dispersion (A) (pigment concentration 17% by mass) ... 44.1% by mass
・ Glycerin: 8.5% by mass
・ 3-Methyl-1,3-butanediol ... 17.0% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
・ 2-Pyrrolidone: 2.0% by mass
-Silicone modified acrylic resin of Synthesis Example 1 (solid content concentration 30% by mass) ... 6.7% by mass
-Alkali dispersible alumina sol 1 of Production Example 1 (solid content concentration 20% by mass) ... 15.0% by mass
Water-soluble polyurethane compound (W5661, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) ... 1.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Amine organic pH adjuster ... 0.6% by mass
・ Pure water: remaining

(Example 2)
-Preparation of inkjet recording ink b-
In Example 1, except that the alkali-dispersible alumina sol 1 of Production Example 1 was replaced with the alkali-dispersible alumina sol 2 of Production Example 2 and the ink formulation was as follows, the same as in Example 1, for inkjet recording Ink b was produced.
[Ink prescription]
Pigment dispersion (A) (pigment concentration 17% by mass) ... 44.1% by mass
・ Glycerin: 8.5% by mass
・ 3-Methyl-1,3-butanediol ... 17.0% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
・ 2-Pyrrolidone: 2.0% by mass
-Silicone modified acrylic resin of Synthesis Example 1 (solid content concentration 30% by mass) ... 6.7% by mass
-Alkali-dispersible alumina sol 2 of Production Example 2 (solid content concentration 25% by mass) ... 12.0% by mass
Water-soluble polyurethane compound (W5661, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) ... 1.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Amine organic pH adjuster ... 0.6% by mass
・ Pure water: remaining

(Example 3)
-Preparation of inkjet recording ink c-
Ink jet recording ink c was produced in the same manner as in Example 1, except that the alkali-dispersible alumina sol 1 of Production Example 1 was replaced with the alkali-dispersible alumina sol 3 of Production Example 3.

(Comparative Example 1)
-Preparation of ink d for inkjet recording-
Ink jet recording ink d was produced in the same manner as in Example 1 except that the ink formulation in Example 1 was changed as follows.
[Ink prescription]
Pigment dispersion (A) (pigment concentration 17% by mass) ... 44.1% by mass
・ Glycerin: 8.5% by mass
・ 3-Methyl-1,3-butanediol ... 17.0% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
・ 2-Pyrrolidone: 2.0% by mass
-Silicone modified acrylic resin of Synthesis Example 1 (solid content concentration 30% by mass) ... 6.7% by mass
Water-soluble polyurethane compound (W5661, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) ... 1.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Amine organic pH adjuster ... 0.6% by mass
・ Pure water: remaining

(Comparative Example 2)
-Preparation of inkjet recording ink e-
Ink jet recording ink e was prepared in the same manner as in Example 1 except that the ink formulation was changed as follows in Example 1.
[Ink prescription]
Pigment dispersion (A) (pigment concentration 17% by mass) ... 44.1% by mass
・ Glycerin: 8.5% by mass
・ 3-Methyl-1,3-butanediol ... 17.0% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
・ 2-Pyrrolidone: 2.0% by mass
-Silicone modified acrylic resin of Synthesis Example 1 (solid content concentration 30% by mass) ... 6.7% by mass
Colloidal silica (Snowtex 20, manufactured by Nissan Chemical Industries, solid content concentration 20% by mass, pH 9.6, average particle size 15 nm) ... 15.0% by mass
Water-soluble polyurethane compound (W5661, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) ... 1.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Amine organic pH adjuster ... 0.6% by mass
・ Pure water: remaining

(Comparative Example 3)
-Preparation of inkjet recording ink-
Ink jet recording ink f was produced in the same manner as in Example 1 except that the ink formulation in Example 1 was changed as follows.
[Ink prescription]
Pigment dispersion (A) (pigment concentration 17% by mass) ... 44.1% by mass
・ Glycerin: 8.5% by mass
・ 3-Methyl-1,3-butanediol ... 17.0% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
・ 2-Pyrrolidone: 2.0% by mass
-Silicone modified acrylic resin of Synthesis Example 1 (solid content concentration 30% by mass) ... 6.7% by mass
Acidic alumina sol (alumina sol 520, manufactured by Nissan Chemical Industries, Ltd., solid content concentration: 20% by mass, pH 3.8) ... 15.0% by mass
Water-soluble polyurethane compound (W5661, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) ... 1.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Amine organic pH adjuster ... 0.6% by mass
・ Pure water: remaining

<Volume average particle diameter of particles in ink (D50)>
Next, the volume average particle diameter (D50) of the particles contained in the prepared inkjet recording inks a to f was measured at 23 ° C. and 55% using a particle size distribution meter (Microtrack UPA-150EX, manufactured by Nikkiso Co., Ltd.). Measured in an RH environment. The results are shown in Table 1.

<Image evaluation>
Using each ink jet recording ink produced, an image was output in a plain paper-fast (no color matching) mode using an ink jet printer (manufactured by Ricoh Co., Ltd., GX5000). The applied voltage waveform was prepared so that the ink adhesion amount of the solid image portion in this mode was 8.2 g / m ² .
A PPC paper 4200 manufactured by Xerox Corporation was used as a recording medium, and image density, ejection stability, and storage stability were evaluated as follows. The results are shown in Table 1.

<Image density>
The image density of a solid image prepared using each ink for ink jet recording was measured with an X-Rite densitometer (manufactured by X-Rite).

<Discharge stability>
After printing a printed matter using each ink jet recording ink, the printer was left in a 40 ° C. environment for one month with the printer head capped. Whether or not the discharge state of the printer after being left is restored to the initial discharge state was evaluated based on the following criteria for the number of cleaning operations.
〔Evaluation criteria〕
○: When recovered by one operation △: When recovered by two or three operations ×: When recovery is not observed even after three or more operations

<Storage stability>
Each ink for ink jet recording is sealed in a polyethylene container, and after storing at 70 ° C. for 2 weeks, the volume average particle diameter, surface tension, and viscosity of the ink are measured, and evaluated according to the following criteria based on the change rate from the initial physical properties. did.
The surface tension of the ink was measured with an automatic surface tension meter DY-300 manufactured by Kyowa Interface Science Co., Ltd. at a measurement temperature of 23 ° C.
The viscosity of the ink was measured with a RE500L viscometer manufactured by Toki Sangyo Co., Ltd. at a measurement temperature of 25 ° C.
〔Evaluation criteria〕
A: When the rate of change is less than 5% in all items of the volume average particle size, surface tension, and viscosity of the ink ○: The rate of change in all items of the volume average particle size, surface tension, and viscosity of the ink Is less than 10%. Δ: When the rate of change is less than 30% in all items of the volume average particle diameter, surface tension, and viscosity of the ink. X: Volume average particle diameter, surface tension, and ink of the ink. When the rate of change is 30% or more for at least one item of viscosity

(Preparation Example 1)
<Preparation of Polymer Fine Particle Dispersion 1 Containing Color Material>
<< Preparation of phthalocyanine pigment-containing polymer fine particle dispersion >>
-Preparation of polymer solution-
The inside of a 1 L volume flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube, and dropping funnel was sufficiently purged with nitrogen gas, and then 11.2 g of styrene, 2.8 g of acrylic acid, and lauryl methacrylate 12 0.0 g, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were charged and heated to 65 ° C.
Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, styrene macromer (trade name: AS-6, manufactured by Toagosei Co., Ltd.) A mixed solution of 36.0 g, mercaptoethanol 3.6 g, azobisdimethylpareronitrile 2.4 g and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours. After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours.
After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added, and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50% by mass.

(2) Preparation of aqueous dispersion of polymer fine particles 28 g of polymer solution obtained in (1), phthalocyanine pigment (Dainippon Ink Chemical Co., Ltd., trade name: TGR-SD) 26 g, 1 mol / L potassium hydroxide 13.6 g of aqueous solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water were sufficiently stirred, and then kneaded 20 times using a three-roll mill.
The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain a blue polymer fine particle dispersion.
The average particle diameter (D50) measured by the particle size distribution meter (Microtrac UPA-150EX, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 93 nm.

(Preparation Example 2)
<Preparation of Colorant-Containing Polymer Fine Particle Dispersion 2>
-Preparation of dimethylquinacridone pigment-containing polymer fine particle dispersion-
The phthalocyanine pigment of the colorant-containing polymer fine particle dispersion 1 is obtained by adding C.I. I. A reddish purple polymer fine particle dispersion was obtained in the same manner as the colorant-containing fine polymer particle dispersion 1 except that the pigment red 122 was used.
The average particle diameter (D50) measured by the particle size distribution meter (Microtrac UPA-150EX, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 127 nm.

(Preparation Example 3)
<Preparation of Colorant-Containing Polymer Fine Particle Dispersion 3>
-Preparation of monoazo yellow pigment-containing polymer fine particle dispersion-
The phthalocyanine pigment of the colorant-containing polymer fine particle dispersion 1 is obtained by adding C.I. I. A yellow polymer fine particle dispersion was obtained in the same manner as the colorant-containing polymer fine particle dispersion 1 except that the pigment yellow 74 was used.
The average particle diameter (D50) measured by the particle size distribution meter (Microtrac UPA-150EX, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 76 nm.

Example 4
<Preparation of inkjet recording ink g (cyan)>
Using the colorant-containing polymer fine particle dispersion 1 obtained in Preparation Example 1, an ink liquid was prepared according to the following formulation, and adjusted with a 10% by weight aqueous solution of lithium hydroxide so that the pH was 9. Then, it filtered with the membrane filter with an average hole diameter of 0.8 micrometer, and produced the ink g for inkjet recording.
[Ink prescription]
-Colorant-containing polymer fine particle dispersion 1 of Preparation Example 1 ... 15.0 mass% (solid content)
・ 1,5-pentanediol: 15.0% by mass
・ Glycerin: 15.0% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
-Alkali dispersible alumina sol 3 of Production Example 3 (solid content concentration 20% by mass) ... 15.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Ion exchange water

(Comparative Example 4)
<Ink for inkjet recording h (cyan)>
Using the colorant-containing polymer fine particle dispersion 1 obtained in Preparation Example 1, an ink liquid was prepared according to the following formulation, and adjusted with a 10% by weight aqueous solution of lithium hydroxide so that the pH was 9. Then, it filtered with the membrane filter with an average hole diameter of 0.8 micrometer, and produced the ink h for inkjet recording.
[Ink prescription]
-Colorant-containing polymer fine particle dispersion 1 of Preparation Example 1 ... 15.0 mass% (solid content)
・ 1,5-pentanediol: 15.0% by mass
・ Glycerin: 15.0% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Ion exchange water

(Example 5)
<Ink for inkjet recording i (magenta)>
Using the colorant-containing polymer fine particle dispersion 2 of Preparation Example 2, an ink liquid was prepared according to the following formulation, and adjusted with a 10% by mass aqueous solution of lithium hydroxide so that the pH was 9. Then, it filtered with the membrane filter with an average hole diameter of 0.8 micrometer, and produced the ink i for inkjet recording.
[Ink prescription]
-Colorant-containing polymer fine particle dispersion 2 of Preparation Example 2 ... 15.0 mass% (solid content)
・ 1,6-hexanediol: 22.5% by mass
・ Glycerin: 7.5% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
Alkali dispersible alumina sol 3 (solid content concentration 20% by mass) 15.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Ion exchange water

(Comparative Example 5)
<Ink for inkjet recording j (magenta)>
An ink liquid was prepared according to the following formulation using the colorant-containing polymer fine particle dispersion 2 of Preparation Example 2, and adjusted with a 10% by weight aqueous solution of lithium hydroxide so that the pH was 9. Then, it filtered with the membrane filter with an average hole diameter of 0.8 micrometer, and produced the ink j for inkjet recording.
[Ink prescription]
-Colorant-containing polymer fine particle dispersion 2 of Preparation Example 2 ... 15.0 mass% (solid content)
・ 1,6-hexanediol: 22.5% by mass
・ Glycerin: 7.5% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Ion exchange water

(Example 6)
<Inkjet recording ink k (yellow)>
Using the colorant-containing polymer fine particle dispersion 3 of Preparation Example 3, an ink solution was prepared according to the following formulation, and adjusted with a 10% by weight lithium hydroxide aqueous solution so that the pH was 9. Then, it filtered with the membrane filter with an average hole diameter of 0.8 micrometer, and produced the ink k for inkjet recording.
[Ink prescription]
-Colorant-containing polymer fine particle dispersion 3 of Preparation Example 3 15.0% by mass (solid content)
・ 1,6-hexanediol: 22.5% by mass
・ Glycerin: 7.5% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
Alkali dispersible alumina sol 3 (solid content concentration 20% by mass) 15.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Ion exchange water

(Comparative Example 6)
<Ink for inkjet recording l (yellow)>
Using the colorant-containing polymer fine particle dispersion 3 of Preparation Example 3, an ink solution was prepared according to the following formulation, and adjusted with a 10% by weight lithium hydroxide aqueous solution so that the pH was 9. Then, it filtered with the membrane filter with an average hole diameter of 0.8 micrometer, and produced the ink l for inkjet recording.
[Ink prescription]
-Colorant-containing polymer fine particle dispersion 3 of Preparation Example 3 15.0% by mass (solid content)
・ 1,6-hexanediol: 22.5% by mass
・ Glycerin: 7.5% by mass
・ 2-ethyl-1,3-hexanediol: 2.0% by mass
-Fluorosurfactant (FS-300, manufactured by DuPont, active ingredient 40 mass%) ... 2.5 mass%
-Antiseptic and fungicidal agent (Proxel LV, manufactured by Avecia) ... 0.05% by mass
・ Ion exchange water

  Next, the volume average particle diameter (D50) of the particles in the ink was measured in the same manner as in Examples 1 to 3 and Comparative Examples 1 to 3 for the prepared inks for ink jet recording g to l. The results are shown in Table 2. In addition, image density, ejection stability, and storage stability were evaluated in the same manner as in Examples 1 to 3 and Comparative Examples 1 to 3 using an inkjet printer (manufactured by Ricoh Co., Ltd., GX5000). The results are shown in Table 2.

  From the results of Tables 1 and 2, the inkjet recording inks of the present invention using the alkali-dispersible alumina sols of Examples 1 to 6 have a higher image density than Comparative Examples 1 to 6, ejection stability, and It was found to be excellent in storage stability.

  The ink for ink jet recording of the present invention can be applied to various recordings by an ink jet recording method, and can be suitably applied to, for example, an ink jet printer, a facsimile machine, a copying machine, and the like.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Main body housing | casing 16 Gear mechanism 17 Subscanning motor 18 Carriage 18a Droplet discharge head 19 Platen 20 Ink cartridge 21 Guide shaft 22 Guide shaft 23 Timing belt 25 Gear mechanism 26 Main scanning motor

JP 2008-63573 A JP 2009-0697907 JP 2009-173805 A JP-A-9-227812 JP 2003-25708 A JP 2009-208423 A

Claims (5)

  An ink for ink-jet recording, comprising at least a colorant, a water-soluble organic solvent, water, and an alkali-dispersible alumina sol.   The ink for ink jet recording according to claim 1, wherein the average particle diameter of the colloidal particles in the alkali-dispersible alumina sol is 5 nm to 300 nm.   The ink for inkjet recording according to any one of claims 1 to 2, wherein the content of the alkali-dispersible alumina sol is 1% by mass to 10% by mass as the solid content of the colloidal particles.   An ink cartridge, wherein the ink for ink jet recording according to claim 1 is contained in a container.   An inkjet recording apparatus comprising: an ejection unit that ejects the inkjet recording ink according to claim 1 to form an image.