JP2016108441A - Inkjet water-based ink set, ink cartridge and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet water-based ink set capable of obtaining high image quality equivalent to a solvent-based inkjet ink and an ultraviolet cure type inkjet ink, when directly recording on a non-porous base material.SOLUTION: An inkjet water-based ink set includes a black ink and at least one type of color ink. The black ink and the color ink at least includes water, a pigment, a water-soluble organic solvent and a resin. The pigment used in the black ink is a resin coating type, and the pigment used in the color ink is a self-dispersion type.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous inkjet ink set, an ink cartridge, and an inkjet recording method.

Inkjet printers have advantages such as low noise, low running cost, and easy color printing, and are therefore widely used in general households as digital signal output devices.
In recent years, inkjet technology has been used not only for home use but also for industrial purposes such as displays, posters, and bulletin boards.

  In the industrial application, when a porous substrate is used, there is a problem that the durability such as light resistance, water resistance, and abrasion resistance is inferior, and therefore a non-porous substrate such as a plastic film is used. Inks used for the non-porous substrate have been developed. As the ink, a solvent-based inkjet ink using an organic solvent as a vehicle and an ultraviolet curable inkjet ink mainly composed of a polymerizable monomer are widely used.

  The solvent-based ink-jet ink has a problem in that a large amount of solvent is evaporated in the atmosphere, which places a burden on the environment. Further, the ultraviolet curable ink-jet ink may have a skin sensitization property depending on the monomer used, and further, there is a problem that the application field is limited because it is necessary to incorporate an expensive ultraviolet irradiation device into the printer body. There is.

Therefore, water-based inkjet inks that can form high-quality images and have low environmental impact even when directly recorded on a non-porous substrate have been proposed (see, for example, Patent Documents 1 and 2).
In addition, an ink set using black ink and color ink that can obtain an image having a wide color reproduction range, excellent weather resistance, and high image density has been proposed (for example, see Patent Document 3).

  However, Patent Documents 1 and 2 have a problem that image quality is inferior to that of the solvent-based inkjet ink and the ultraviolet curable inkjet ink even when directly recorded on a non-porous substrate. . Further, Patent Document 3 is a proposal excellent in image density and color reproduction range on paper, and there is no description or suggestion in image quality when applied to a non-porous substrate.

  Accordingly, an object of the present invention is to provide a water-based ink set for ink jets that can obtain high image quality comparable to that of solvent-based ink jet inks and ultraviolet curable ink jet inks.

  The aqueous inkjet ink set according to the present invention as a means for solving the problems includes a black ink and at least one color ink, and the black ink and the color ink include at least water, a pigment, The pigment used for the black ink containing a water-soluble organic solvent and a resin is a resin-coated type, and the pigment used for the color ink is a self-dispersing type.

  According to the present invention, there is provided an aqueous ink set for inkjet which can solve the above-described problems and achieve the above-mentioned object, and can obtain high image quality comparable to that of solvent-based inkjet ink and ultraviolet curable inkjet ink. Can be provided.

FIG. 1 is a schematic diagram illustrating an example of a serial type ink jet recording apparatus. FIG. 2 is a schematic diagram showing a configuration in the main body of the apparatus of FIG.

(Water-based ink set for inkjet)
The aqueous inkjet ink set of the present invention is a set containing black ink and at least one color ink. The color inks are cyan ink, magenta ink, and yellow ink, which are chromatic color inks.

  In order to solve the above-mentioned problems, the present inventors conducted extensive studies, and as a result, the present inventors obtained knowledge that the dispersion state of the pigment in the ink greatly contributed to the improvement of the image density. . Specifically, when a resin-coated pigment is used in black ink and a self-dispersing pigment is used in color ink, high image quality, that is, high image density can be obtained efficiently on a non-porous substrate. it can.

<Ink>
The ink contains water, a pigment, a water-soluble organic solvent, and a resin, and further contains other components as necessary.
Examples of the ink include black ink and at least one color ink. The pigment used for the black ink is a resin-coated type, and the pigment used for the color ink is a self-dispersing type.

<< Black ink >>
-Pigment-
Examples of the pigment used in the black ink include a resin-coated type.
Examples of the pigment (hereinafter also referred to as “black pigment”) used in the resin-coated pigment (hereinafter also referred to as “resin-coated pigment”) include inorganic pigments such as a contact method, a furnace method, and a thermal method. And carbon black produced by a known method such as aniline black. Examples of the organic pigment include aniline black. These may be used alone or in combination of two or more. Among these, those having good affinity with the water-soluble organic solvent are preferable. The resin-coated pigment refers to a pigment in which part or all of the pigment surface is encapsulated with a polymer.

  Examples of the black pigment include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black; metal compounds such as copper and iron (CI pigment black 11). Aniline black (CI pigment black 1) and the like. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as a manufacturing method of the said resin-coated pigment, A well-known method can be used, For example, a part or the whole of the pigment surface wraps with a polymer (polymer) etc. are mentioned.

  Examples of the polymer include vinyl polymers (vinyl polymers) such as polyacrylic acid esters, styrene-acrylic acid copolymers and polystyrene; polyesters; polyamides; polyimides; silicon-containing polymers; These may be used alone or in combination of two or more.

  Examples of the polymer include a polymer in which a monomer or oligomer compound having an acryloyl group, a methacryloyl group, a vinyl group, or an allyl group as a double bond is polymerized by a known polymerization method using a polymerization initiator. .

  Examples of the monomer include styrene; tetrahydrofurfuryl acrylate; butyl methacrylate; (α, 2, 3, or 4) -alkylstyrene; (α, 2, 3, or 4) -alkoxystyrene; 3,4-dimethyl. Styrene; α-phenylstyrene; divinylbenzene; vinylnaphthalene; dimethylamino (meth) acrylate; dimethylaminoethyl (meth) acrylate; dimethylaminopropylacrylamide; N, N-dimethylaminoethyl acrylate; acryloylmorpholine; N-isopropylacrylamide; N, N-diethylacrylamide; methyl (meth) acrylate; ethyl (meth) acrylate; propyl (meth) acrylate; ethylhexyl (meth) acrylate Other alkyl (meth) acrylates; methoxydiethylene glycol (meth) acrylates; diethylene glycol (meth) acrylates having ethoxy groups, propoxy groups, butoxy groups, or polyethylene glycol (meth) acrylates; cyclohexyl (meth) acrylates; benzyl (meth) acrylates Phenoxyethyl (meth) acrylate; isobornyl (meth) acrylate; hydroxyalkyl (meth) acrylate; fluorine-containing, chlorine-containing, or silicon-containing (meth) acrylate; (meth) acrylamide; maleic acid amide; (meth) acrylic acid, etc. When introducing a crosslinked structure in addition to the monofunctional group of (mono, di, tri, tetra, poly) ethylene glycol di (meth) acrylate; 1,4-butanediol (meth) acrylate 1,5-pentanediol (meth) acrylate; 1,6-hexanediol (meth) acrylate; 1,8-octanediol (meth) acrylate; 1,10-decanediol (meth) acrylate; trimethylolpropane tri (meth) ) Acrylate; glycerin (di, tri) (meth) acrylate; di (meth) acrylate of ethylene oxide adduct of bisphenol A or bisphenol F; neopentyl glycol di (meth) acrylate; pentaerythritol tetra (meth) acrylate; Examples thereof include compounds having an acrylic group or a methacrylic group such as erythritol hexa (meth) acrylate. These may be used alone or in combination of two or more.

  Examples of the polymerization initiator include potassium persulfate and ammonium persulfate, hydrogen persulfate, azobisisobutyronitrile, benzoyl peroxide, dibutyl peroxide, peracetic acid, cumene hydroperoxide, t-butylhydroxyl. Common initiators used for radical polymerization such as peroxide and paramentane hydroxyperoxide are exemplified. These may be used alone or in combination of two or more. Among these, a water-soluble polymerization initiator is preferable.

  Examples of the method of including the black pigment using the polymer include a phase inversion emulsification method, an acid folding method, and a forced emulsification method.

As the phase inversion emulsification method, for example, a self-water dispersible resin (self-water dispersible polymer) in which some acid groups are neutralized with a base is dissolved in an organic solvent to obtain a solution. Examples thereof include a method of phase inversion emulsification by mixing a colored resin solution obtained by dispersing or dissolving a pigment and an aqueous medium containing water as an essential component.
At the time of phase inversion emulsification, resin-coated pigment particles including the pigment in the polymer are generated, and subsequently the black pigment is included in the polymer by removing the organic solvent from the aqueous medium. A resin-coated pigment can be suitably obtained.
Another specific example of the phase inversion emulsification method is, for example, after adding polyester to a ketone solvent together with a black pigment and ionizing carboxyl groups in the polyester by adding a neutralizing agent to the ketone solution. , And a method of phase inversion emulsification by adding water. By distilling off the ketone solvent from the mixed solution, a resin-coated pigment containing the black pigment with the polyester can be suitably obtained.

As the acid precipitation method, for example, by adding an acidic compound to an aqueous dispersion of a black pigment finely dispersed by a polymer having a carboxyl group neutralized with a basic compound, Examples include a method in which the resin is strongly fixed to the black pigment and acidified by making the resin neutral or acidic and making the resin hydrophobic.
Next, after the acid precipitation, a basic compound is added to the aqueous dispersion, and the carboxyl group of the polymer is neutralized again, whereby an aqueous dispersion of the resin-coated pigment containing the black pigment with the polymer is obtained. It can be suitably obtained.

  As the forced emulsification method, for example, a neutralizing agent is added to a solution or dispersion obtained by adding a vinyl polymer having a silicon macromer as a copolymer component and a black pigment in an organic solvent. Examples include a method of emulsifying by adding water after ionizing a salt-forming group in a vinyl polymer. Next, during the emulsification, a resin-coated pigment containing a pigment with a polymer can be suitably obtained by distilling off the organic solvent.

  Examples of the resin-coated pigment include pigments encapsulating pigment fine particles described in JP-B-7-94634 or JP-A-8-59715; polymers on the surface described in International Publication No. 1999/51690. Pigments having a group bonded thereto; modified particles having a polymer group having a halogen group described in US Pat. No. 6,103,380 can be suitably used.

<< Color ink >>
-Pigment-
Examples of the pigment used in the color ink include a self-dispersing type. When the color ink is composed of a plurality of color inks, the pigments used in the plurality of color inks are all self-dispersing.

  Examples of pigments (hereinafter also referred to as “color pigments”) used in the self-dispersing pigment (hereinafter also referred to as “self-dispersing pigment”) include inorganic pigments such as titanium oxide, iron oxide, and calcium carbonate. , Barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, etc., and organic pigments such as azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments; phthalocyanine pigments, perylene pigments , Perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, and other polycyclic pigments; basic dye-type chelates, acidic dye-type chelates, etc. Examples of pigments include nitroso pigments. These may be used alone or in combination of two or more. Among these, those having good affinity with the water-soluble organic solvent are preferable. The self-dispersing pigment refers to a pigment that is treated with a hydrophilic group-providing agent in a solvent and has a hydrophilic group on the surface.

Examples of color pigments used in the self-dispersing pigment include:
C. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155;
C. I. Pigment orange 5, 13, 16, 17, 36, 43, 51;
C. 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;
C. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38;
C. I. Pigment blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 16, 17: 1, 56, 60, 63;
C. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like. These may be used alone or in combination of two or more.

The self-dispersing pigment refers to a pigment that is treated with a hydrophilic group-providing agent in a solvent and has a hydrophilic group on the surface.
As confirmation of the pigment being self-dispersing, for example, the pigment component is precipitated and separated by centrifugation, washed with acetone to remove soluble components, and then the obtained solid is treated with high-purity water. For example, a method of redispersing in high-purity water when mixed and sufficiently stirred can be used. When the pigment is redispersed in high purity water, it is a self-dispersing pigment in which hydrophilic groups are chemically bonded to the pigment surface.

  There is no restriction | limiting in particular as a manufacturing method of the said self-dispersion type pigment, A well-known method can be used, for example, it treats with a hydrophilic group provision agent in a solvent, and processes a hydrophilic group on the surface etc. Is mentioned.

--Hydrophilic group imparting agent--
Examples of the hydrophilic group-imparting agent include a sulfur-containing treatment agent and a carboxylating agent.
---- Sulfur-containing treatment agent ---
Examples of the treatment method containing sulfur include sulfuric acid, fuming sulfuric acid, sulfur trioxide, chlorosulfuric acid, fluorosulfuric acid, amidosulfuric acid, sulfonated pyridine salt, and sulfamic acid. These may be used alone or in combination of two or more. Of these, sulfonating agents such as sulfur trioxide, sulfonated pyridine salts, and sulfamic acid are preferable.
The sulfonating agent imparts at least one of sulfonic acid (—SO ₂ OH) and sulfinic acid (—RSO ₂ H, R is a C1-C12 alkyl group, or a phenyl group and a modified product thereof). It is the processing agent for doing.

  Examples of the solvent used in the reaction include those that do not react with a sulfur-containing treatment agent and that the pigment is insoluble or hardly soluble. Specifically, sulfolane, N-methyl-2-pyrrolidone, dimethylacetamide, quinoline, hexamethylphosphoric triamide, chloroform, dichloroethane, tetrachloroethane, tetrachloroethylene, dichloromethane, nitromethane, nitrobenzene, liquid sulfur dioxide, carbon disulfide, Examples include trichlorofluoromethane. These may be used alone or in combination of two or more.

As the treatment method using the treatment agent containing sulfur, for example, a treatment agent containing sulfur is added to a dispersion in which a pigment is dispersed in the solvent, heated at 60 to 200 ° C., and 3 to 10 hours. The following may be performed by stirring.
Specifically, the color pigment is dispersed in the solvent with a high-speed shear dispersion with a high-speed mixer or the like, or with an impact dispersion with a bead mill or a jet mill, to form a slurry (dispersion), and then gently stirring, A treatment agent containing sulfur can be added to introduce hydrophilic groups onto the surface of the pigment. At this time, the introduction amount of the hydrophilic group is determined depending on the reaction conditions and the type of the treatment agent containing sulfur. Next, the processing agent containing a solvent and residual sulfur can be removed from the color pigment slurry by heat treatment. Moreover, it can be set as a desired aqueous dispersion by repeating water washing, ultrafiltration, reverse osmosis, centrifugation, filtration, etc. as needed.

As another treatment method using the treatment agent containing sulfur, for example, the sulfonic acid (—SO ₂ OH), and sulfinic acid (—RSO ₂ H, R is a C1-C12 alkyl group, or a phenyl group, And at least one of the modified product thereof with an alkali compound, a sulfonate anion group (—SO ₃ ⁻ ) and a sulfinate anion group (—RSO ₂ , R are C1 to C12) as hydrophilic groups. And a self-dispersing pigment having at least one of an alkyl group, a phenyl group, and a modified product thereof on the surface.

  Examples of the alkali compound include compounds in which a cation becomes an alkali metal ion or a monovalent ion represented by the following general formula (1).

In the general formula (1), R ¹ , R ² , R ³ , and R ⁴ may be the same or different, and include a hydrogen atom, an alkyl group, a hydroxyalkyl group, a halogenated alkyl group, and the like. Lithium ions (Li ⁺ ); potassium ions (K ⁺ ); sodium ions (Na ⁺ ); ammonium ions (NH ₄ ⁺ ); and alkanolamine cations such as triethanolamine cations are preferable.

In the general formula (1), examples of Z include a hydroxide anion.
Examples of the hydroxide anion include ammonia; alkanolamines such as monoethanolamine, diethanolamine, N, N-butylethanolamine, triethanolamine, propanolamine, aminomethylpropanol, 2-aminoisopropanol; monovalent alkali metal And hydroxides (LiOH, NaOH, KOH) and the like.

--- Carboxylating agent ---
As the treatment method using the carboxylating agent, for example, an oxidizing agent such as hypohalite such as sodium hypochlorite or potassium hypochlorite is used to partially bond the color pigment surface (C = C , C-C), and oxidation treatment. In addition, a carboxylating agent means the processing agent for providing a carboxylic acid group (-COOH).

  As a treatment method using the carboxylating agent, for example, a color pigment is preliminarily dispersed in a high-speed shear dispersion with a high-speed mixer or the like in the solvent, or is impact-dispersed with a bead mill or a jet mill to form a slurry (dispersion). Thereafter, the dispersion and a hypohalite such as sodium hypochlorite having an effective halogen concentration of 10% or more and 30% or less are mixed in an appropriate amount of water and heated at 60 ° C. to 80 ° C. for 5 hours or more. Preferably, it can be performed by stirring for 10 hours or more. Next, the solvent and the remaining carboxylating agent can be removed from the surface-treated color pigment slurry by heat treatment. Moreover, it can be set as a desired aqueous dispersion by repeating water washing, ultrafiltration, reverse osmosis, centrifugation, filtration, etc. as needed.

Further, the self-dispersing pigment has a carboxylic acid anion group (—COO ⁻ ) as a hydrophilic group on the surface by treating carbon black particles having a carboxylic acid group (—COOH) with an alkali compound. It may be.
In addition, the kind of alkali compound and the processing method by an alkali compound are the same as that of the processing agent containing the above-mentioned sulfur.

Further, in addition to the treatment with sulfur and the treatment with the carboxylating agent, a carboxylic acid group can also be imparted by physical oxidation such as plasma treatment. Any processing method that can be dispersed in a suitable manner can be used.
In the carboxylic acid introduction treatment with the hydrophilic group-imparting agent, a quinone group or the like may be introduced in a small quantity, but can be used without any problem as long as the pigment can be self-dispersed. .

  The content of the pigment is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 10% by mass or less with respect to the total amount of the ink. When the content is 0.1% by mass or more, the image density is increased and the image quality can be improved. When the content is 10% by mass or less, reliability such as fixing property, ejection stability, and clogging is achieved. Can be improved.

<< Common components of black ink and color ink >>
-Water-soluble organic solvent-
The water-soluble organic solvent is contained in the black ink and at least one color ink, and the water-soluble organic solvent used in the black ink and the color ink may be the same or different. .
The water-soluble organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyhydric alcohol compounds, polyhydric alcohol alkyl ether compounds, polyhydric alcohol aryl ether compounds, and nitrogen-containing heterocyclic compounds. Amide compounds, amine compounds, sulfur-containing compounds, propylene carbonate (propylene carbonate) (boiling point: 240 ° C.), ethylene carbonate (boiling point: 261 ° C.), and the like. These may be used alone or in combination of two or more. Among these, a water-soluble organic solvent having a boiling point of 200 ° C. or lower is preferable.

  Examples of the polyhydric alcohol compound include ethylene glycol (boiling point: 196 ° C.), diethylene glycol (boiling point: 244 ° C.), triethylene glycol (boiling point: 287 ° C.), propylene glycol (1,2-propanediol) (boiling point: 188 ° C), dipropylene glycol (boiling point: 231 ° C), tripropylene glycol (boiling point: 273 ° C), 1,3-propanediol (boiling point: 214 ° C), 1,2-butanediol (boiling point: 194 ° C), 1,3-butanediol (boiling point: 208 ° C), 2,3-butanediol (boiling point: 183 ° C), 1,4-butanediol (boiling point: 230 ° C), 1,2-pentanediol (boiling point: 206 ° C) ), 2,4-pentanediol (boiling point: 201 ° C.), 2-methyl-1,3-butanediol (boiling point: 203 ° C.) 3-methyl-1,3-butanediol (boiling point: 203 ° C.), 1,5-pentanediol (boiling point: 242 ° C.), 2,2-dimethyl-1,3-propanediol (boiling point: 208 ° C.), 2-methyl-1,3-propanediol (boiling point: 124 ° C.), 2-methyl-2,4-pentanediol (boiling point: 198 ° C.), 1,2-hexanediol (boiling point: 223 ° C.), 1,6 -Hexanediol (boiling point: 250 ° C), 2,5-hexanediol (boiling point: 217 ° C), 2-ethyl-1,3-hexanediol (boiling point: 243 ° C), tetraethylene glycol (boiling point: 314 ° C), Glycerin (boiling point: 290 ° C.), 1,2,6-hexanetriol (boiling point: 178 ° C.), 1,2,4-butanetriol (boiling point: 170 ° C.), 1,2,3-butanetriol ( Point: 175 ° C.), and the like. These may be used alone or in combination of two or more.

  Examples of the polyhydric alcohol alkyl ether compound include ethylene glycol monoethyl ether (boiling point: 135 ° C.), ethylene glycol monobutyl ether (boiling point: 171 ° C.), diethylene glycol methyl ether (boiling point: 194 ° C.), diethylene glycol monoethyl ether ( Boiling point: 202 ° C., triethylene glycol methyl ether (boiling point: 249 ° C.), triethylene glycol ethyl ether (boiling point: 256 ° C.), diethylene glycol-n-hexyl ether (boiling point: 259 ° C.), ethylene glycol phenyl ether (boiling point: 237 ° C.), ethylene glycol-n-propyl ether (boiling point: 150 ° C.), diethylene glycol-n-butyl ether (boiling point: 171 ° C.), tetraethylene glycol monomethyl ester Ter (boiling point: 159 ° C), dipropylene glycol monomethyl ether (boiling point: 188 ° C), propylene glycol monoethyl ether (boiling point: 133 ° C), propylene glycol-n-butyl ether (boiling point: 171 ° C), propylene glycol-t- Butyl ether (boiling point: 153 ° C.), dipropylene glycol-n-propyl ether (boiling point: 213 ° C.), tripropylene glycol methyl ether (boiling point: 243 ° C.), tripropylene glycol-n-propyl ether (boiling point: 261 ° C.), And propylene glycol phenyl ether (boiling point: 243 ° C.). These may be used alone or in combination of two or more. When at least one selected from 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol is contained, a high image density can be easily obtained.

  Examples of the polyhydric alcohol aryl ether compound include ethylene glycol monophenyl ether (boiling point: 237 ° C.), ethylene glycol monobenzyl ether (boiling point: 256 ° C.), and the like. These may be used alone or in combination of two or more.

  Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone (boiling point: 204 ° C.), N-hydroxyethyl-2-pyrrolidone (boiling point: 309 ° C.), 2-pyrrolidone (boiling point: 245 ° C.), Examples include 1,3-dimethylimidazolidinone (boiling point: 220 ° C.), ε-caprolactam (boiling point: 137 ° C.), N-methylpyrrolidinone (boiling point: 202 ° C.), and the like. These may be used alone or in combination of two or more.

  Examples of the amide compound include formamide (boiling point: 210 ° C.), N-methylformamide (boiling point: 199 ° C.), N, N-dimethylformamide (boiling point: 153 ° C.), and the like. These may be used alone or in combination of two or more.

  Examples of the amine compound include monoethanolamine (boiling point: 170 ° C), diethanolamine (boiling point: 280 ° C), triethanolamine (boiling point: 208 ° C), monoethylamine (boiling point: 17 ° C), diethylamine (boiling point: 56). ° C), triethylamine (boiling point: 90 ° C), and the like. These may be used alone or in combination of two or more.

  Examples of the sulfur-containing compound include dimethyl sulfoxide (boiling point: 189 ° C.), sulfolane (boiling point: 285 ° C.), thiodiethanol (boiling point: 165 ° C.), thiodiglycol (boiling point: 165 ° C.), and the like. These may be used alone or in combination of two or more.

  Among these, as the water-soluble organic solvent having a boiling point of 200 ° C. or lower, ethylene glycol (boiling point: 196 ° C.), propylene glycol (1,2-propanediol, boiling point: 188 ° C.), 1,2-butanediol (Boiling point: 194 ° C.), 2,3-butanediol (boiling point: 183 ° C.), 2-methyl-2,4-pentanediol (boiling point: 198 ° C.), dipropylene glycol monomethyl ether (boiling point: 188 ° C.), propylene Glycol-n-butyl ether (boiling point: 171 ° C), propylene glycol-t-butyl ether (boiling point: 153 ° C), diethylene glycol methyl ether (boiling point: 194 ° C), ethylene glycol-n-propyl ether (boiling point: 150 ° C), ethylene Glycol-n-butyl ether (boiling point: 171 ° C.) Preferably, alcohol having a boiling point of 150 ° C. or higher and 200 ° C. or lower is more preferable, and a diol having a boiling point of 180 ° C. or higher and 200 ° C. or lower from the viewpoint of better compatibility with the resin and more film forming property. -Propanediol (boiling point: 188 ° C), 1,2-butanediol (boiling point: 194 ° C), 2,3-butanediol (boiling point: 183 ° C), 2-methyl-2,4-pentanediol (boiling point: 198) ), Dipropylene glycol monomethyl ether (boiling point: 188 ° C), 1,2-propanediol (boiling point: 188 ° C), 1,2-butanediol (boiling point: 194 ° C), 2,3-butanediol (Boiling point: 183 ° C.) is particularly preferred.

The content of the water-soluble organic solvent having a boiling point of 200 ° C. or lower is preferably 50% by mass or more based on the total amount of the water-soluble organic solvent in the ink. When the content is 50% by mass or more, when ink jet recording is performed on a non-porous substrate, color boundary bleeding between the black ink and the color ink, so-called bleeding phenomenon, is preferably improved, and a high image Quality can be obtained, and the drying property of the ink is good, and a sufficient coating film can be formed with the ink.
This is because when the resin-coated pigment contained in the black ink is directly recorded on a non-porous substrate such as a resin film, the surface of the pigment is covered with resin. The affinity with the non-porous substrate is improved, and the interfacial tension between the black ink and the non-porous substrate is reduced. As a result, the wettability of the black ink to the non-porous substrate is relatively improved, and the black ink flows into the color ink, which may cause bleeding. However, when 50% or more of the content of the water-soluble organic solvent has a boiling point of 200 ° C. or less, the evaporation rate of the droplets deposited on the non-porous substrate is increased, and the fluidity of the ink is rapidly increased. Lost. Accordingly, the phenomenon that the black ink flows into the color ink is avoided, and it is estimated that an image free from bleeding is obtained.

  The content of the water-soluble organic solvent having a boiling point exceeding 250 ° C. is preferably less than 10% by mass and more preferably not contained with respect to the total amount of the water-soluble organic solvent in the ink from the viewpoint of promoting the evaporation rate. . An evaporation rate can be accelerated | stimulated as the said content is less than 10 mass%.

  As content of the said water-soluble organic solvent, 20 mass% or more and 70 mass% or less are preferable with respect to the ink whole quantity, and 30 mass% or more and 60 mass% or less are more preferable. When the content is 20% by mass or more, it becomes difficult to dry the ink, so that sufficient ejection stability can be obtained. When the content is 70% by mass or less, the viscosity can be kept low, and thus the ejection stability is improved. Can be made.

-Resin-
The resin is contained in the black ink and at least one color ink, and the resin used in the black ink and the color ink may be the same or different.

  As said resin, you may contain dispersing agents, such as surfactant, as needed, but the self-emulsification type emulsion is preferable from the point which improves the performance of a coating film more.

  The acid value of the resin is preferably 5 mgKOH / g or more and 100 mgKOH / g or less, and more preferably 5 mgKOH / g or more and 50 mgKOH / g or less from the viewpoint of water dispersibility. When the acid value is 5 mgKOH / g or more and 100 mgKOH / g or less, scratch resistance and chemical resistance can be improved.

The resin preferably has, for example, an anionic group from the viewpoint of water dispersibility.
Examples of the anionic group include a carboxyl group and a sulfonic acid group from the viewpoint of water dispersion stability.
There is no restriction | limiting in particular as a method to introduce | transduce the said anionic group into the said resin, According to the objective, it can select suitably, It can obtain by making the monomer which has the said anionic group react.

  The volume average particle size of the resin is preferably 10 nm to 1,000 nm, more preferably 10 nm to 200 nm, and particularly preferably 10 nm to 50 nm. When the volume average particle size is 10 nm or more and 1,000 nm or less, it can be suitably used for an ink jet recording apparatus. The volume average particle diameter can be measured using, for example, a particle size analyzer (trade name: Microtrac Model UPA 9340, manufactured by Nikkiso Co., Ltd.).

  There is no restriction | limiting in particular as said resin, According to the objective, it can select suitably, For example, a urethane resin, a polyester resin, an acrylic resin, a vinyl acetate resin, a styrene resin, a butadiene resin, a styrene-butadiene type | system | group Examples thereof include resins, vinyl chloride resins, acrylic styrene resins, and acrylic silicone resins. These may be used alone or in combination of two or more. Among these, urethane resin is preferable from the viewpoint of image quality and image fastness.

-Urethane resin-
The urethane resin can promote pinning of ink droplets, and can improve the image quality. Ink droplet pinning means that as the volatile components in the ink evaporate, the viscosity of the ink droplets increases and a resin film is formed on the surface. This causes the ink droplets to lose their fluidity and be fixed on the spot. Means that
In addition, since the urethane resin has high wear resistance, the image fastness of the recorded material can be made stronger, and it is suitable for the recorded material used in harsh environments such as outdoor use. Ink is obtained.

  There is no restriction | limiting in particular in the said urethane resin, According to the objective, it can select suitably, For example, what is obtained by making a polyol and polyisocyanate react is mentioned.

  Examples of the polyol include polyether polyol, polycarbonate polyol, and polyester polyol. These may be used alone or in combination of two or more. Among these, polycarbonate polyol is preferable from the viewpoint of image fastness.

  Examples of the polyether polyol include those obtained by addition polymerization of alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator.

Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, glycerin, and trimethylolethane. And trimethylolpropane. These may be used alone or in combination of two or more.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran. These may be used alone or in combination of two or more.
Examples of the polyether polyol include polyoxytetramethylene glycol, polyoxypropylene glycol and the like from the viewpoint of obtaining a binder for ink jet recording ink that can impart very excellent scratch resistance. These may be used alone or in combination of two or more.

Examples of the polycarbonate polyol include those obtained by reacting a carbonate with a polyol, and those obtained by reacting phosgene with bisphenol A and the like.
Examples of the carbonate ester include methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, and diphenyl carbonate. These may be used alone or in combination of two or more.
Examples of the polyol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1, 2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8 -Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcinol , Bisphenol-A, bisphe Relatively low molecular weight dihydroxy compounds such as polyol-F, 4,4′-biphenol; polyether polyols such as polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol; polyhexamethylene adipate, polyhexamethylene succinate, poly Examples thereof include polyester polyols such as caprolactone. These may be used alone or in combination of two or more.

Examples of the polyester polyol include those obtained by esterifying low molecular weight polyols and polycarboxylic acids, polyesters obtained by ring-opening polymerization reaction of cyclic ester compounds such as ε-caprolactone, and copolymers thereof. Examples include polyester. These may be used alone or in combination of two or more.
Examples of the low molecular weight polyol include ethylene glycol and propylene glycol. These may be used alone or in combination of two or more.
Examples of the polycarboxylic acid include succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, and anhydrides or ester-forming derivatives thereof. These may be used alone or in combination of two or more.

  Examples of the polyisocyanate include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate and naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene Examples thereof include aliphatic or aliphatic cyclic structure-containing diisocyanates such as diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate. These may be used alone or in combination of two or more. Among these, aliphatic or aliphatic cyclic structure-containing diisocyanates are mentioned because a coating film having very high long-term weather resistance that can be used in outdoor applications such as posters and signboards can be obtained.

As the resin, a commercially available product may be used, or an appropriately synthesized resin may be used.
Examples of the commercially available products include microgel E-1002, E-5002 (styrene-acrylic resin fine particles, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin fine particles, manufactured by DIC Corporation), and Boncoat 5454 (styrene). -Acrylic resin fine particles, manufactured by DIC Corporation, SAE-1014 (styrene-acrylic resin fine particles, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin fine particles, manufactured by Seiden Chemical Co., Ltd.), Primal AC- 22, AC-61 (acrylic resin fine particles, manufactured by Rohm and Haas), Nanoacryl SBCX-2821, 3688 (acrylic silicone resin fine particles, manufactured by Toyochem Co., Ltd.), # 3070 (methyl methacrylate polymer resin fine particles, Mikuni Color Co., Ltd.) And the like. These may be used alone or in combination of two or more.

  The content of the resin is preferably 1% by mass or more and 10% by mass or less, and more preferably 5% by mass or more and 10% by mass or less with respect to the total amount of the ink. When the content is 1% by mass or more and 10% by mass or less, fixability and ink stability can be improved, and when the content is 5% by mass or more and 10% by mass or less, the smoothness of the ink layer, and Fixability to a non-porous substrate can be improved.

-Water-
There is no restriction | limiting in particular as said water, According to the objective, it can select suitably, For example, pure water, such as ion-exchange water, high purity water, ultrafiltration water, reverse osmosis water, distilled water; ultrapure water etc. Can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

-Other ingredients-
As said other component, the other component currently used for normal ink other than the said water, the said pigment, the said water-soluble organic solvent, and the said resin can be contained.

  There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, surfactant, antiseptic / antifungal agent, rust preventive agent, pH adjuster etc. are mentioned. These may be used alone or in combination of two or more.

--Surfactant--
The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include amphoteric surfactants, nonionic surfactants, anionic surfactants, fluorine-based surfactants, and silicone-based surfactants. Surfactant etc. are mentioned. These may be used alone or in combination of two or more. Among these, nonionic surfactants are preferable from the viewpoints of dispersion stability and image quality.
Examples of the nonionic surfactant include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer; sorbitan fatty acid ester; polyoxyethylene Sorbitan fatty acid ester; ethylene oxide adduct of acetylene alcohol and the like. These may be used alone or in combination of two or more.

  As content of the said surfactant, 0.1 to 5 mass% is preferable. When the content is 0.1% by mass or more, wettability to a non-porous substrate can be ensured, so that the image quality can be improved, and when the content is 5% by mass or less, the ink hardly foams. Thus, excellent discharge stability can be obtained.

Examples of the antiseptic / antifungal agent include 1,2-benzisothiazolin-3-one, sodium benzoate, sodium dehydroacetate, sodium sorbate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, and the like. Can be mentioned.
Examples of the rust preventive include acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, dicyclohexyl ammonium nitrite and the like.

  The pH adjuster is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting the ink, and can be appropriately selected according to the purpose. For example, lithium hydroxide, water Hydroxides of alkali metal elements such as sodium oxide and potassium hydroxide; alkali metal carbonates such as lithium carbonate, sodium carbonate and potassium carbonate; quaternary ammonium hydroxides; amines such as diethanolamine and triethanolamine; water Ammonium oxide; quaternary phosphonium hydroxide and the like.

-Ink production method-
As the method for producing the ink, for example, water, a pigment, a water-soluble organic solvent, a resin, a surfactant, and, if necessary, other components are dispersed or dissolved in an aqueous medium, and appropriately stirred and mixed. can do. As the stirring and mixing, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, a stirrer using a normal stirrer blade, a magnetic stirrer, a high-speed disperser, or the like can be used.

-Recording media-
When the recording medium is applied to a non-porous substrate, an image having image quality can be obtained.

(ink cartridge)
The ink cartridge of the present invention includes an ink cartridge that stores black ink in a container and an ink cartridge that stores color ink in a container.
The ink cartridge contains the ink in a container and further includes other members appropriately selected as necessary.

  The container is not particularly limited, and its shape, structure, size, material and the like can be appropriately selected according to the purpose. For example, an ink bag formed of an aluminum laminate film, a resin film, etc. What has at least etc. is mentioned.

(Inkjet recording method)
The inkjet recording method of the present invention includes an ink flying process in which stimulation is applied and the ink is ejected to record an image on a recording medium, and a heating process in which the recording medium on which the image is recorded is heated.

-Ink flight process-
The ink flying step is a step of forming an image by applying a stimulus to the ink and causing the ink to fly.

  There is no restriction | limiting in particular as said irritation | stimulation, According to the objective, it can select suitably, For example, heat | fever (temperature), a pressure, a vibration, light, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, heat and pressure are preferable.

  For example, the ink used in the inkjet water-based ink set may be formed by deforming a diaphragm that forms a wall surface of the ink flow path using a piezoelectric element as a pressure generating unit that pressurizes the ink in the ink flow path. A so-called piezo method (for example, see Japanese Examined Patent Publication No. 2-51734), in which the volume of the ink flow path is changed to eject ink droplets; A so-called thermal method (see, for example, Japanese Patent Publication No. 61-59911); a diaphragm and an electrode that form a wall surface of an ink flow path are arranged to face each other and are generated between the diaphragm and the electrode. An electrostatic system that discharges ink droplets by changing the volume of the ink flow path by deforming the diaphragm by electrostatic force (for example, Japanese Patent Laid-Open No. 6-71882) Reference), and the like.

  The size of the droplets of the ink to be ejected is preferably 3 pl or more and 40 pl or less, for example, and the ejection jet speed is preferably 5 m / s or more and 20 m / s or less. 1 kHz or more is preferable, and the resolution is preferably 300 dpi or more.

-Heating process-
The heating step is a step of heating the recording medium on which an image is recorded.
As the ink jet recording method, high image quality recording can be performed on the non-porous substrate, but it is possible to cope with the formation of images with higher image quality, abrasion resistance, and higher adhesion, and high-speed recording conditions. Therefore, it is preferable to heat the non-porous substrate after recording. When a heating step is performed after recording, film formation of the resin contained in the ink is promoted, and thus the image fastness of the recorded matter can be improved.

As the apparatus used for the heating step, many known apparatuses can be used, and examples thereof include forced air heating, radiation heating, conduction heating, high frequency drying, microwave drying, and the like. These may be used alone or in combination of two or more.
The heating temperature can be changed according to the type and amount of the water-soluble organic solvent contained in the ink and the minimum film-forming temperature of the resin emulsion to be added, and also depending on the type of the substrate to be printed. Can be changed.
The heating temperature is preferably high in terms of drying property and film forming temperature, more preferably 40 ° C. or more and 120 ° C. or less, and particularly preferably 50 ° C. or more and 90 ° C. or less. When the heating temperature is 40 ° C. or higher and 120 ° C. or lower, damage to the non-porous substrate to be printed due to heat can be prevented, and occurrence of non-ejection due to warming of the ink head can be suppressed.

  Here, an ink jet recording apparatus capable of recording using the ink will be described with reference to the drawings. In addition, although the case where a non-porous base material is used is demonstrated, it can record similarly also with respect to porous base materials, such as paper. The ink jet recording apparatus includes a serial type (shuttle type) scanned by a carriage and a line type equipped with a line type head. FIG. 1 is a schematic diagram illustrating an example of a serial type ink jet recording apparatus. . FIG. 2 is a schematic diagram showing a configuration in the main body of the apparatus of FIG.

  As shown in FIG. 1, the ink jet recording apparatus includes an apparatus main body 101, a paper feed tray 102 mounted on the apparatus main body 101, a paper discharge tray 103, and an ink cartridge loading unit 104. On the upper 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 for attaching and detaching the ink cartridge 201. Reference numeral 111 denotes an upper cover, and reference numeral 112 denotes a front surface of the front cover.

In the apparatus main body 101, as shown in FIG. 2, a carriage 133 is slidably held in the main scanning direction by a guide rod 131 and a stay 132, which are guide members horizontally mounted on left and right side plates (not shown). Then, the scanning is moved by a main scanning motor (not shown).
The carriage 133 has a plurality of ink ejection openings of a recording head 134 including four inkjet recording heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.

As the ink jet recording head constituting the recording head 134, a piezoelectric actuator such as a piezoelectric element, a thermal actuator using phase change due to liquid film boiling using an electrothermal transducer such as a heating resistor, a metal phase due to temperature change, etc. A shape memory alloy actuator using a change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.
Further, the carriage 133 is equipped with sub tanks 135 for each color for supplying ink of each color to the recording head 134. The ink is supplied to the sub tank 135 from an ink cartridge 201 of the present invention loaded in the ink cartridge loading unit 104 via an ink supply tube (not shown) and replenished.

On the other hand, the substrate 142 is separated and fed one by one from the substrate stacking unit 141 as a sheet feeding unit for feeding the substrate 142 loaded on the substrate loading unit (pressure plate) 141 of the sheet feeding tray 102. A half paddle (sheet feeding roller 143) and a sheet feeding roller 143 are opposed to each other, and a separation pad 144 made of a material having a large friction coefficient is provided. The separation pad 144 is urged toward the sheet feeding roller 143 side.
As a transport unit for transporting the base material 142 fed from the paper feed unit on the lower side of the recording head 134, a transport belt 151 for electrostatically attracting and transporting the base material 142, and a paper feed unit On the conveyor belt 151, the counter roller 152 for transporting the base material 142 fed through the guide 145 with the transport belt 151 being sandwiched between the counter roller 152 and the base material 142 fed substantially vertically upward is changed by about 90 °. And a leading end pressure roller 155 urged toward the conveyor belt 151 by a pressing member 154, and charging as charging means for charging the surface of the conveyor belt 151. A roller 156 is provided.

  The conveyor belt 151 is an endless belt, is stretched between a heater-type conveyor roller 157 and a tension roller 158, and can circulate in the belt conveyance direction. The transport belt 151 includes, for example, a surface layer serving as a substrate adsorption surface formed of a resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), and the surface layer. And a back layer (medium resistance layer, grounding layer) that is controlled by carbon with the same material. A heater-type guide member 161 is disposed on the back side of the conveyance belt 151 so as to correspond to a printing area by the recording head 134. Note that, as a paper discharge unit for discharging the base material 142 recorded by the recording head 134, a separation claw 171 for separating the base material 142 from the transport belt 151, a paper discharge roller 172, and a paper discharge roller 173, After the substrate 142 is dried with hot air by a fan heater (not shown), it is output to the paper discharge tray 103 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 base material 142 returned by the reverse rotation of the transport belt 151, 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 ink jet recording apparatus, the base material 142 is separated and fed one by one from the paper feed unit, and the base material 142 fed substantially vertically upward is guided by the guide 145, and the conveyance belt 151, the counter roller 152, It is sandwiched between and conveyed. Further, the leading end is guided by the conveying guide 153 and pressed against the conveying belt 151 by the leading end pressure 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 base material 142 is electrostatically attracted to the conveyance belt 151 and conveyed.
Therefore, by driving the recording head 134 according to the image signal while moving the carriage 133, ink droplets are ejected onto the stopped base material 142 to record one line, and the base material 142 is conveyed by a predetermined amount. After that, the next line is recorded. Upon receiving a recording end signal or a signal that the rear end of the base material 142 reaches the recording area, the recording operation is finished, and the base material 142 is discharged onto the paper discharge tray 103.

<Recorded material>
The recorded matter has an image formed on the recording medium using the ink.
Examples of the recording medium include non-porous substrates.
The non-porous substrate refers to a substrate having a surface with low water permeability, absorbability and / or adsorptivity, and includes a material which does not open to the outside even if there are many cavities inside.
More quantitatively, it refers to a base material having a water absorption of 10 mL / m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method.
As the non-porous substrate, for example, plastic films such as a vinyl chloride resin film, a PET film, and a polycarbonate film are suitable, but other non-porous substrates and conventional paper such as plain paper and inorganic coated porous media are suitable. Sufficient performance is also shown for porous media that have been used.

  Examples of the present invention and comparative examples will be described below, but the present invention is not limited to these examples. Further, “parts” and “%” shown in Examples and Comparative Examples represent “parts by mass” and “% by mass” unless otherwise specified. In addition, in the Example and comparative example which are shown below, content of each component shows a pure conversion value.

<Preparation of black pigment dispersion>
—Preparation of Black Pigment Dispersion A (Resin Coated Type) 1—
After sufficiently replacing the inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube, and dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate Then, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercaptoethanol were mixed 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 hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, azobismethylvalero A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours. After dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile 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 azobismethylvaleronitrile 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%.
After sufficiently stirring 28 g of the polymer solution, 42 g of carbon black (trade name: FW100, manufactured by Degussa), 13.6 g of 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 13.6 g of ion-exchanged water, a roll mill was used. And kneaded. The obtained paste was put into 200 g of pure water and stirred sufficiently. Then, methyl ethyl ketone and water were distilled off with an evaporator, and this dispersion was further removed with polyvinylidene fluoride having an average pore size of 5.0 μm to remove coarse particles. Pressure filtration was performed with a membrane filter (trade name: Durapore, manufactured by Merck Millipore) to obtain a black pigment dispersion A (resin-coated type) having a pigment solid content of 15% and a solid content concentration of 20%.

-Preparation of black pigment dispersion B (self-dispersing type) 2-
100 g of carbon black (trade name: Black Pearls (registered trademark) 1000, manufactured by Cabot Corporation, BET specific surface area: 343 m ² / g, DBPA 105 mL / 100 g) was added to 2.5N (normative) sodium hypochlorite solution 3, 000 mL, stirred at a temperature of 60 ° C. and a speed of 300 rpm, reacted for 10 hours and oxidized to obtain a reaction liquid containing a pigment having a carboxylic acid group attached to the surface of carbon black. Next, the reaction solution was filtered, and the pigment having a carboxylic acid group added to the surface of the carbon black separated by filtration was neutralized with a sodium hydroxide solution and subjected to ultrafiltration. Next, ultrafiltration through a dialysis membrane was performed using the ion-exchanged water, and further ultrasonic dispersion was performed to obtain a black pigment dispersion B (self-dispersing type) in which the pigment solid content was concentrated to 20%.

-Preparation of Black Pigment Dispersion C (Activator Dispersion Type) 3-
After pre-mixing the following prescription mixture, it was circulated and dispersed for 7 hours in a disk type bead mill (KDL type, manufactured by Shinmaru Enterprises Co., Ltd., media: 0.3 mm diameter zirconia ball), and black pigment dispersion C (active agent) Dispersion type) was obtained.
Carbon black (trade name: Monarch 800, manufactured by Cabot Corporation) 20 parts Anionic surfactant (trade name: Pionine A-51-B, manufactured by Takemoto Yushi Co., Ltd.) 4 parts Ion-exchanged water 76 parts

<Preparation of cyan pigment dispersion>
-Preparation of Cyan Pigment Dispersion A (self-dispersing type) 1-
In preparation 2 of the black pigment dispersion B (self-dispersing type), black pigment dispersion B was used except that Pigment Blue 15: 4 (trade name: SMART Cyan 3154BA, manufactured by SENSIENT) was used instead of carbon black. A cyan pigment dispersion A (self-dispersing type) was obtained in the same manner as in Preparation 2 of (self-dispersing type).

<Preparation of magenta pigment dispersion>
-Preparation of magenta pigment dispersion A (self-dispersing type) 1-
In preparation 2 of the black pigment dispersion B (self-dispersing type), instead of carbon black, Pigment Red 122 (trade name: Pigment Red 122, manufactured by Sun Chemical Co.) was used, except that Black Pigment Dispersion B ( Magenta pigment dispersion A (self-dispersing type) was obtained in the same manner as in Preparation 2 of (Self-dispersing type).

<Preparation of yellow pigment dispersion>
-Preparation of yellow pigment dispersion A (resin-coated type) 1-
In Preparation 1 of Black Pigment Dispersion A, the same procedure as in Preparation 1 of Black Pigment Dispersion A was used except that Pigment Yellow 74 (trade name: SMART Yellow 3074BA, manufactured by SENSIENT) was used instead of carbon black. Thus, a yellow pigment dispersion A (resin-coated type) was obtained.

-Preparation of yellow pigment dispersion B (self-dispersing type) 2-
In Preparation 2 of Black Pigment Dispersion B, the same procedure as in Preparation 2 of Black Pigment Dispersion B was used except that Pigment Yellow 74 (trade name: SMART Yellow 3074BA, manufactured by SENSIENT) was used instead of carbon black. Thus, a yellow pigment dispersion B (self-dispersing type) was obtained.

-Preparation of yellow pigment dispersion C (active agent dispersion type) 3-
In Preparation 3 of Black Pigment Dispersion C, the same procedure as in Preparation 3 of Black Pigment Dispersion C was used except that Pigment Yellow 74 (trade name: SMART Yellow 3074BA, manufactured by SENSIENT) was used instead of carbon black. Thus, a yellow pigment dispersion C (active agent dispersion type) was obtained.

<Preparation of resin emulsion>
-Preparation of polycarbonate urethane resin emulsion 1
In a reaction vessel into which a stirrer, a reflux condenser and a thermometer were inserted, polycarbonate diol (a reaction product of 1,6-hexanediol and dimethyl carbonate) 1,500 g, 2,2-dimethylolpropionic acid (DMPA) 220 g, And 1347 g of N-methylpyrrolidone (NMP) were charged under a nitrogen stream and heated to 60 ° C. to dissolve DMPA. Next, 1,445 g of 4,4′-dicyclohexylmethane diisocyanate and 2.6 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C., followed by urethanization reaction for 5 hours, reaction of isocyanate-terminated urethane prepolymer A mixture was obtained. The reaction mixture was cooled to 80 ° C., 149 g of triethylamine was added thereto, and 4,340 g was extracted from the mixture, and added to a mixed solution of 5,400 g of water and 15 g of triethylamine with vigorous stirring. Next, 1,500 g of ice was added, 626 g of 35% 2-methyl-1,5-pentanediamine aqueous solution was added to carry out a chain extension reaction, and the solvent was distilled off so that the solid concentration was 30%. A polycarbonate urethane resin emulsion was obtained.
It was 35 nm when the volume average particle diameter of the obtained polycarbonate-type urethane resin emulsion was measured using the particle size analyzer (brand name: Microtrac MODEL UPA9340, Nikkiso Co., Ltd. product).

-Preparation of polyester urethane resin emulsion 2-
Preparation 1 of the polycarbonate-based urethane resin emulsion 1 except that polyester polyol (trade name: Polylite OD-X-2420, manufactured by DIC Corporation) was used instead of polycarbonate diol in Preparation 1 of the polycarbonate-based urethane resin emulsion. In the same manner, a polyester urethane resin emulsion (solid content: 30%) was obtained.
It was 54 nm when the volume average particle diameter of the obtained polyester-type urethane resin emulsion was measured using the particle size analyzer (Brand name: Microtrac MODEL UPA9340, Nikkiso Co., Ltd. product).

-Preparation of polyether urethane resin emulsion 3-
Preparation 1 of the polycarbonate-based urethane resin emulsion 1 except that polyether polyol (trade name: Hiflex D2000, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used instead of the polycarbonate diol in Preparation 1 of the polycarbonate-based urethane resin emulsion. In the same manner as above, a polyether-based urethane resin emulsion (solid content: 30%) was obtained.
It was 13 nm when the volume average particle diameter of the obtained polyether-type urethane resin emulsion was measured using the particle size analyzer (Microtrac MODEL UPA9340, Nikkiso Co., Ltd. product).

-Preparation of acrylic resin emulsion 4-
A reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer was charged with 900 g of ion-exchanged water and 1 g of sodium lauryl sulfate, and the temperature was raised to 70 ° C. while purging with nitrogen under stirring. Next, the internal temperature was kept at 70 ° C., 4 g of potassium persulfate as a polymerization initiator was added and dissolved to obtain a reaction solution. Next, an emulsion prepared by previously stirring 450 g of ion-exchanged water, 3 g of sodium lauryl sulfate, 20 g of acrylamide, 365 g of styrene, 545 g of butyl acrylate, and 10 g of methacrylic acid was continuously added to the reaction solution over 4 hours. It was dripped. After completion of dropping, aging was performed for 3 hours to obtain a reaction mixture of acrylic resin emulsion. After cooling the reaction mixture to room temperature, ion exchange water and aqueous sodium hydroxide solution were added to adjust the pH to 8 to obtain an acrylic resin emulsion (solid content: 30%).
It was 88 nm when the volume average particle diameter of the obtained acrylic resin emulsion was measured using the particle size analyzer (Microtrac MODEL UPA9340, Nikkiso Co., Ltd. product).

-Preparation of polyester resin emulsion 5-
As the polyester resin emulsion, a commercially available product (trade name: Elitel KT-8803, manufactured by Unitika Ltd., solid content: 29.8%) was used. It was 115 nm when the volume average particle diameter of the said polyester resin emulsion was measured using the particle size analyzer (Microtrac MODEL UPA9340, Nikkiso Co., Ltd. product).

-Preparation of black ink (Bk-1) 1
Black pigment dispersion A (resin coated type) 20% by mass, polycarbonate urethane resin emulsion 15% by mass, 1,2-propanediol 20% by mass, diethylene glycol-n-butyl ether 15% by mass, secondary alcohol ethoxylate (product) Name: Softanol EP-5035, manufactured by Nippon Shokubai Co., Ltd., 2% by weight, 1,2-benzisothiazolin-3-one (trade name: Proxel LV, manufactured by Avicia Co., Ltd., antiseptic / antifungal agent) 0.1% by mass and 27.9% by mass of high purity water were mixed and stirred, and filtered through a 0.1 μm pore size polypropylene filter (trade name: Metricel, manufactured by Pall) to prepare a black ink (Bk-1). .

-Preparation of ink other than black ink (Bk-1) 2-
In the preparation 1 of the black ink (Bk-1), the black ink (Bk-1) was changed to the composition and content shown in Tables 1 to 4 below instead of the black ink (Bk-1). Each ink was prepared in the same manner as in the preparation of Tables 1 to 4 show the composition and content of each ink.

Example 1
An aqueous inkjet ink set having a black ink (Bk-1) and a cyan ink (Cy-1) was produced.

(Examples 2 to 13 and Comparative Examples 1 to 4)
About Examples 2-13 and Comparative Examples 1-4, except having changed into the ink set of Table 5-Table 7, it carried out similarly to Example 1, and produced the ink set. Tables 5-7 show the ink sets of Examples 2-13 and Comparative Examples 1-4.

  Next, the following evaluation was performed using the produced ink sets of Examples 1 to 13 and Comparative Examples 1 to 4.

-Image density-
The prepared ink set is filled into an inkjet printer (trade name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.), and solid images of black and color are printed on a white PVC sheet (trade name: IJ5331, manufactured by 3M Japan Co., Ltd.). And dried by forced air heating at 80 ° C. for 1 hour to obtain a recorded matter. Product name: X-Rite 938 (manufactured by Videojet X-Rite Co., Ltd.) was used, and the density of the solid image portion was measured four times for each of the black ink and the color ink, and the average measured value was evaluated. An average measured value of image density of 2.2 or higher is a level that is not problematic in practice, and it can be evaluated that the image quality is high. As long as the image density of each ink in the ink set of black ink and one color ink is 2.2 or more, even if the ink set is a combination of black ink and two or three color inks, The image density of each ink is 2.2 or more, and the black ink and two or three color inks are combined by evaluating the image density of each ink in the ink set of black ink and one color ink. It can be confirmed that a high image density can be obtained even in the ink set.

-Color boundary bleeding-
About the recorded matter obtained above, the boundary portion between the black ink and the color ink was visually evaluated for “color boundary bleeding” based on the following evaluation criteria. “C” or higher is a level where there is no practical problem.
-Evaluation criteria-
A: There is no blur at the boundary part, or it is almost inconspicuous, and it is a high quality image. B: A slight blur is observed at the boundary part, but the image has no problem. C: Blur is seen at the boundary part. An image that can be used in practice D: Extremely blurred at the boundary and poor quality

-Image robustness-
About the recorded matter obtained above, the solid portion was rubbed with a dry cotton (Kanakin No. 3) with a weight of 400 g, and “image fastness” was evaluated based on the following evaluation criteria. “C” or higher is a level where there is no practical problem. In consideration of the use in outdoor applications, the evaluation criteria for image robustness were considerably stricter than those recorded on ordinary paper.
-Evaluation criteria-
A: The image does not change even after rubbing 50 times or more. B: Some scratches remain at the stage of rubbing 50 times, but the image density is not affected. C: The image density is slightly changed between 31 times and 50 times or less. Although there is a decrease, it can be actually used. D: Image density decreases during rubbing 11 times or more and 30 or less E: Image density decreases by rubbing 10 times or less.

  As is apparent from the results of Tables 5 to 7, it can be seen that the ink-jet aqueous ink set of each Example is excellent in image density. Moreover, it turns out that the water-based ink set for inkjets of each Example is excellent in image fastness. Thereby, the water-based ink set for inkjet according to the present invention is suitable for outdoor use.

As an aspect of this invention, it is as follows, for example.
<1> having black ink and at least one color ink;
The black ink and the color ink contain at least water, a pigment, a water-soluble organic solvent, and a resin,
The pigment used in the black ink is a resin-coated type,
The pigment used in the color ink is a self-dispersing type, and is an aqueous ink set for inkjet.
<2> The aqueous inkjet ink set according to <1>, wherein 50% by mass or more of the content of the water-soluble organic solvent has a boiling point of 200 ° C. or less.
<3> The inkjet ink set according to any one of <1> to <2>, wherein the resin is a urethane resin.
<4> The inkjet water-based ink set according to any one of <1> to <3>, wherein the water-soluble organic solvent contains an alcohol having a boiling point of 150 ° C. or higher and 200 ° C. or lower.
<5> The water-soluble organic solvent is at least one selected from 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol, and any one of <1> to <4> The ink-jet water-based ink set described.
<6> An ink cartridge comprising an ink used for the water-based inkjet ink set according to any one of <1> to <5>, contained in a container.
<7> An ink flying process of recording an image on a recording medium by applying a stimulus to the ink used in the inkjet water-based ink set according to any one of <1> to <5>, and causing the ink to fly. ,
A heating step of heating the recording medium on which an image is recorded.
<8> The inkjet recording method according to <7>, wherein the recording medium is a non-porous substrate.
<9> A recorded matter having an image recorded with the ink used in the aqueous inkjet ink set according to any one of <1> to <5>.

JP 2005-220352 A JP 2011-094082 A Japanese Patent No. 3991219

Claims (8)

A black ink and at least one color ink;
The black ink and the color ink contain at least water, a pigment, a water-soluble organic solvent, and a resin,
The pigment used in the black ink is a resin-coated type,
An aqueous inkjet ink set, wherein the pigment used in the color ink is a self-dispersing type.   The water-based ink set for inkjet according to claim 1, wherein 50% by mass or more of the content of the water-soluble organic solvent has a boiling point of 200 ° C or lower.   The water-based ink set for inkjet according to claim 1, wherein the resin is a urethane resin.   The aqueous ink set for inkjet according to any one of claims 1 to 3, wherein the water-soluble organic solvent contains an alcohol having a boiling point of 150 ° C or higher and 200 ° C or lower.   The inkjet water-based ink according to any one of claims 1 to 4, wherein the water-soluble organic solvent is at least one selected from 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol. set.   An ink cartridge comprising an ink used for the inkjet water-based ink set according to claim 1 contained in a container. An ink flying step of applying a stimulus to the ink used in the aqueous inkjet ink set according to claim 1 and causing the ink to fly to record an image on a recording medium;
A heating step of heating the recording medium on which an image is recorded.   The ink jet recording method according to claim 7, wherein the recording medium is a non-porous substrate.