JP6503863B2 - Image forming set, image forming apparatus, and image forming method - Google Patents

Description

  The present invention relates to an image forming set, an image forming apparatus, and an image forming method.

  In the ink jet recording system, it is known to apply a post-processing liquid to the surface of an image formed by discharging an aqueous ink in order to improve the gloss of the image.

The post-treatment liquid is applied after fixing the image formed by discharging the aqueous ink applied to the recording medium, but after the post-treatment liquid discharges the aqueous ink to form an image, the image is formed. May be applied to the surface of the image in an unfixed state.
The post-treatment liquid contains components such as resin and wax, and the resin and the wax form a uniform coating film on the surface of the image formed by discharging the aqueous ink. Glossiness is given. However, when the post-processing liquid is applied to the surface of the image in a state where the image formed by discharging the aqueous ink is not fixed, the post-processing liquid is mixed into the image, and the surface of the image And a uniform coating film can not be formed, and there is a problem that the glossiness of the image is deteriorated. The unfixed state means a state in which an image formed by discharging an aqueous ink is undried and the image is not fixed.

Therefore, in order to realize high-speed printing, the solubility parameter (hereinafter sometimes referred to as “SP value”) of the water-soluble organic solvent in the ink excellent in the ink absorbability of the ink-receptive particles and the ink-receptive particles A recording material has been proposed in which the difference between the SP value of the monomer component and the SP value is less than 5, and the SP value of the water-soluble organic solvent in the ink is 17.5 or less (see, for example, Patent Document 1). ).
In addition, 50% by mass or more of water with respect to the total mass and 5% by mass or more of the solvent with respect to the total mass are excellent in the maintainability of the water-based ink, and 50% by mass or more of the solvent An ink set that is a solvent of (MPa) ^1/2 (13.4 (cal / cm ³ ) ^1/2 ) or less has been proposed (see, for example, Patent Document 2).

In Patent Document 1, the difference between the SP value of the water-soluble organic solvent of the post-treatment liquid and the SP value of the water-soluble organic solvent in the aqueous ink is small, and the image formed by discharging the aqueous ink is unfixed. When the post-treatment liquid is applied, the image and the post-treatment liquid are easily mixed, and the post-treatment liquid does not form a uniform coating film on the surface of the image, and the glossiness of the image can not be obtained. is there.
In addition, when the said patent document 2 calculates the difference of SP value of water-based ink and maintenance liquid from an Example, 0.05 (cal / cm < ³ >) < ^1/2 > or more 1.13 (cal / cm < ³ >) ^1/2 Because the size is small as described below, the image formed by discharging aqueous ink and the maintenance liquid are easily mixed, and even if the maintenance liquid is applied to the surface of the image, the gloss can not be obtained, and Patent document 2 makes it a subject the improvement of the maintainability of the nozzle surface of an inkjet head, and does not describe the subject of a gloss improvement.

  Therefore, an object of the present invention is to provide an image forming set in which the glossiness of an image can be obtained.

The image forming set of the present invention as a means for solving the above problems is an aqueous ink containing a colorant, a water-soluble organic solvent, and water, at least one of a urethane resin and an acrylic resin, and a water-soluble organic solvent And a post-treatment liquid containing water, wherein the SP value in the mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is the water-soluble organic solvent in the aqueous ink and the water 1.5 (cal / cm ³ ) ^1/2 or more lower than the SP value in the mixed solution of
In the present invention, when the organic solvent is water-soluble, for example, when gently mixed with pure water, it means that it does not separate and exist in the two layers after the flow is stopped.

  According to the present invention, it is possible to solve the above-mentioned problems in the prior art, to achieve the above-mentioned object, and to provide a set for image formation in which the glossiness of an image is obtained.

FIG. 1 is a schematic view (side view) showing an example of an image forming apparatus used in the present invention. FIG. 2 is a schematic block diagram of a control unit in FIG. FIG. 3 is a schematic view showing an example of the head arrangement in the head unit of the image forming apparatus used in the present invention. FIG. 4 is a schematic view showing the heads arranged in the head unit of FIG. FIG. 5 is a view showing an example of an ink cartridge used in the image forming apparatus used in the present invention. 6 is a view including the case (exterior) of the ink cartridge of FIG.

(Set for image formation)
The imaging set of the present invention comprises an aqueous ink, a post-treatment liquid, and optionally further components.

<Water-based ink>
The aqueous ink contains a colorant, a water-soluble organic solvent, and water, and further contains other components as necessary.

<< Colorant >>
There is no restriction | limiting in particular as said coloring agent, According to the objective, it can select suitably, The well-known pigment and dye can be used in water-based ink.
Examples of the colorant include colorant particles in which inorganic particles are coated with carbon black, colorant particles in which inorganic particles are coated with an organic pigment, and colorant particles (resin-coated pigment) in which a pigment is contained in a resin. Can be mentioned. These may be used alone or in combination of two or more.

Examples of the method of coating the inorganic particles with carbon black include a method of in-liquid drying such as coagulation and precipitation, and a dry mixing method in which a mechanical force is applied while mixing.
Examples of the method of coating the inorganic particles with the organic pigment include a method of precipitating the organic pigment in the presence of the inorganic particles, and a method of mechanically mixing and grinding the inorganic particles and the organic pigment. When the organic pigment is excellent in thermal stability, a method such as chemical vapor deposition can be used. In addition, it is preferable to provide an organosilane compound layer formed of a polysiloxane and an alkylsilane, as necessary, between the inorganic particles and the organic pigment. By providing the organosilane compound layer, the adhesion between the inorganic particles and the organic pigment can be improved.

-Inorganic particles-
Examples of the inorganic particles include titanium dioxide, silica, alumina, iron oxide, iron hydroxide, tin oxide and the like. These may be used alone or in combination of two or more.
The shape of the inorganic particles is preferably one having a small aspect ratio, and more preferably spherical. Further, when a color colorant is adsorbed on the surface of the inorganic particles, the inorganic particles are preferably colorless and transparent or white, and when a black colorant is adsorbed, the inorganic particles are preferably black.

  The number average primary particle diameter of the inorganic particles is preferably 7 nm or more and 30 nm or less, and more preferably 7 nm or more and 20 nm or less. The said number average primary particle diameter conforms to JIS Z 890 1-2006 “powder for test and particles for test” 5.44 particle distribution (c) microscopic method, and a sample prepared by shaking method is measured by a transmission electron microscope It is an arithmetic mean value of equivalent circular diameters calculated by observing 100 or more particles from an image observed by magnifying to 50,000 to 1,000,000 times.

-Pigment-
There is no restriction | limiting in particular as said pigment, According to the objective, it can select suitably, For example, an inorganic pigment, an organic pigment, etc. are mentioned. These may be used alone or in combination of two or more.

--Pigment which coats inorganic particles--
As a pigment which covers inorganic particles, an inorganic pigment for black, an organic pigment for black, an organic pigment for color, etc. are mentioned, for example. These may be used alone or in combination of two or more.

Examples of the inorganic pigment for black include carbon black and the like.
Examples of the organic pigment for black include aniline black and the like. These may be used alone or in combination of two or more.

  Examples of the organic pigment for color include, for example, anthraquinone, phthalocyanine blue, phthalocyanine green, diazo pigment, monoazo pigment, pyranthrone, perylene, heterocyclic yellow, quinacridone, and (thio), for example. Indigoid etc. are mentioned. These may be used alone or in combination of two or more. Among these, phthalocyanine pigments, quinacridone pigments, monoazo yellow pigments, diazo yellow pigments and heterocyclic yellow pigments are preferable from the viewpoint of color developability.

Examples of the phthalocyanine pigments include C.I. I. Pigment blue 15: 3, C.I. I. And copper phthalocyanine blue such as C.I. pigment blue 15: 4; aluminum phthalocyanine and the like. These may be used alone or in combination of two or more.
Examples of the quinacridone pigments 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. These may be used alone or in combination of two or more.
Examples of the monoazo yellow pigment include C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 151 and the like. These may be used alone or in combination of two or more.
Examples of the diazo yellow pigments include C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17 and the like. These may be used alone or in combination of two or more.
Examples of the heterocyclic yellow pigment include C.I. I. Pigment yellow 117, C.I. I. Pigment yellow 138 and the like. These may be used alone or in combination of two or more.

  The mass ratio of the inorganic particles to the pigment for coating the inorganic particles (inorganic particles: pigment for coating the inorganic particles) is preferably 3: 1 to 1: 3, and more preferably 3: 2 to 1: 2. preferable. When the mass ratio (inorganic particles: pigment for covering the inorganic particles) is 3: 1 or more and 1: 3 or less, color developability and decrease in coloring power, as well as transparency and color tone can be adjusted.

  A commercial item can be used as a coloring agent which covered the said inorganic particle with the said pigment, As a commercial item, for example, the silica / carbon black by Toda Kogyo Co., Ltd. from the point whose number average primary particle diameter is small Composite material, silica / phthalocyanine C.I. I. Pigment blue 15: 3 composite material, silica / diazo yellow composite material, silica / quinacridone C.I. I. Pigment red 122 composite material and the like. These may be used alone or in combination of two or more.

  The volume average particle diameter (D50) of the colorant is preferably 10 nm or more and 200 nm or less, and more preferably 20 nm or more and 100 nm or less. When the volume average particle diameter is 10 nm or more, dispersion can be performed in a short time and the storage stability of the ink can be improved. When 200 nm or less, the image saturation is good and nozzle clogging is suppressed. Thus, the discharge stability of the ink can be improved. The volume average particle diameter can be measured using a particle size distribution measuring apparatus (trade name: Microtrac UPA, manufactured by Nikkiso Co., Ltd.) or the like.

--Pigment coated on resin--
Examples of the pigment coated on the resin include inorganic pigments and organic pigments.
Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chromium yellow, metal powder, carbon black and the like. These may be used alone or in combination of two or more. Among these, carbon black is preferable.
As said carbon black which is a pigment coat | covered by the said resin, the thing manufactured by well-known methods, such as a contact method, a furnace method, a thermal method, etc. are mentioned, for example.

Examples of the organic pigment include organic pigments for black and organic pigments for colors, and azo pigments, azomethine pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, aniline black and the like are preferable. Among these, azo pigments and polycyclic pigments are more preferable.
Examples of the azo pigment include azo lake, insoluble azo pigment, condensed azo pigment, chelate azo pigment and the like.
Examples of the polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofarone pigments, rhodamine beta lake pigments, etc. . These may be used alone or in combination of two or more.

  Examples of the organic pigment for black include carbon black (CI pigment black 7) compounds such as furnace black, lamp black, acetylene black and channel black; copper, iron (CI pigment black 11), Metal compounds such as titanium oxide, aniline black (CI pigment black 1) and the like can be mentioned. These may be used alone or in combination of two or more.

As said carbon black which is an organic pigment for said black, the thing manufactured by the furnace method, the channel method, etc. are mentioned, for example.
As the carbon black are organic pigments for the black, preferably 15nm or more 40nm or less as the number average primary particle diameter is preferably ^{50 m} 2 / g or more 300 meters ² / g or less as a BET specific surface area, as DBP oil absorption 40 ml / 100 g or more and 150 ml / 100 g or less is preferable, 0.5% or more and 10% or less as volatile component is preferable, and 2 or more and 9 or less is preferable as pH.

  A commercial item can be used as said carbon black which is an organic pigment for said blacks, As a commercial item, for example, trade name: MA7, trade name: MA8, trade name: MA100 etc. (above, Mitsubishi Made by Kagaku Co., Ltd., Raven 1080, Raven 1100 etc. (made by Colombian Carbon Japan Ltd.), trade name: Mogul, trade name: Monarch 700, trade name: Monarch 800 (above, manufactured by Cabot Corporation) and the like.

  Examples of the organic pigment for color include a pigment that can be used for yellow ink, a pigment that can be used for magenta ink, and a pigment that can be used for cyan ink. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as a pigment which can be used for the said yellow ink, According to the objective, it can select suitably, For example, C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 96 and the like. These may be used alone or in combination of two or more. Among these, from the viewpoint of color tone and light resistance, C.I. I. Pigment yellow 74 is preferred.

  There is no restriction | limiting in particular as a pigment which can be used for the said magenta ink, According to the objective, it can select suitably, For example, C.I. I. Pigment red 5, C.I. I. Pigment red 7, C.I. I. Pigment red 12, C.I. I. Pigment bio red 19, C.I. I. Pigment red 122 and the like. These may be used alone or in combination of two or more. Among these, from the viewpoint of color tone and light resistance, C.I. I. Pigment red 122, C.I. I. Pigment Bio Red 19 is preferred.

  There is no restriction | limiting in particular as a pigment which can be used for the said cyan ink, According to the objective, it can select suitably, For example, C.I. I. Pigment blue 1, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4 and the like. These may be used alone or in combination of two or more. Among these, pigment blue 15: 3 is preferable in terms of color tone and light resistance.

  Moreover, as a pigment contained in each ink used by this invention, you may use what was synthesize | combined suitably or you may use a commercial item.

--Resin used for resin coating type pigment--
As resin used for the said resin coating type pigment, an anionic group containing organic polymer compound etc. are mentioned, for example.
The anionic group-containing organic polymer compound can be used without particular limitation, as long as it can impart self-dispersing ability and dissolving ability to water by neutralizing the anionic group.

  As said anionic group, a carboxyl group, a sulfonic acid group, a phosphonic acid group etc. are mentioned, for example. Among these, a carboxyl group is preferable in view of excellent self-dispersing ability and dissolving ability when neutralized with a basic compound.

  As an acid value of the said anionic group, 30 mgKOH / g or more and 150 mgKOH / g or less are preferable, and 50 mgKOH / g or more and 150 mgKOH / g are more preferable. When the acid value is 30 mg KOH / g or more, it is acided out and redispersibility in water after neutralization is good, and the dispersion stability of the pigment can be improved, and it is 150 mg KOH / g or less Thus, it is possible to prevent the hydrophilicity from becoming too high, and to improve the water resistance of the printed matter.

  There is no restriction | limiting in particular as a composition of the said anionic group containing organic high molecular compound, According to the objective, it can select suitably, For example, polyvinyl-type resin, polyester-type resin, amino-type resin, (meth) acrylic-type resin Epoxy resins, polyurethane resins, polyether resins, polyamide resins, unsaturated polyester resins, phenolic resins, silicone resins, fluorine polymer compounds and the like can be mentioned. These may be used alone or in combination of two or more. Among these, (meth) acrylic resins are preferable, and as an essential component, (meth) acrylic acid, and at least one of alkyl ester of (meth) acrylic acid and hydroxyalkyl ester of (meth) acrylic acid. It is more preferable to contain an acrylic resin which further contains styrene if necessary, and the content of these acrylic monomers and styrene is 80% by mass or more. In addition, (meth) acrylic-type resin means methacrylic resin or acrylic resin, and (meth) acrylic acid means methacrylic acid or acrylic acid.

  The acrylic resin can be obtained, for example, by adding an anionic group-containing acrylic monomer and, if necessary, another monomer capable of copolymerizing with the anionic group-containing acrylic monomer, and polymerizing in a solvent. .

Examples of the anionic group-containing acrylic monomer include an acrylic monomer having a carboxyl group, an acrylic monomer having a sulfonic acid group, and an acrylic monomer containing at least one anionic group selected from an acrylic monomer having a phosphonic acid group. It can be mentioned. Among these, acrylic monomers having a carboxyl group are preferable. In addition, a monomer having a crosslinkable functional group can be used to improve the solvent resistance and durability of the capsule layer, and the abrasion resistance of the printed matter.
Examples of the acrylic monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propyl acrylic acid, isopropyl acrylic acid, itaconic acid, fumaric acid and the like.
Examples of the acrylic monomer having a sulfonic acid group include sulfoethyl methacrylate, butyl acrylamide sulfonic acid and the like.
Examples of the acrylic monomer having a phosphonic acid group include phosphoethyl methacrylate and the like.

  As said anionic group containing organic high molecular compound, a carboxyl group containing styrene- acryl type copolymer etc. are mentioned, for example.

  The content of the colorant is preferably 1% by mass to 20% by mass, and more preferably 2% by mass to 15% by mass, with respect to the total amount of the aqueous ink.

<< Mixed solution >>
The mixed solution contains a water-soluble organic solvent and water. The mixed solution refers to one containing a water-soluble organic solvent and water, and also includes one which is classified as a penetrant, a foam inhibitor, etc. in terms of function.

The solubility parameter (solubility parameter, hereinafter also referred to as “SP value”) of the mixed solution in the aqueous ink is preferably 18 (cal / cm ³ ) ^1/2 or more and 22 (cal / cm ³ ) ^1/2 or less. 19 (cal / cm ³ ) ^1/2 or more and 21 (cal / cm ³ ) ^1/2 or less are more preferable.

The SP value in the mixed solution of the water-soluble organic solvent and water contained in the aqueous ink can be calculated from the following formula (A).
SP value (cal / cm ³ ) ^1/2 in mixed solution of water-soluble organic solvent and water in aqueous ink ^1/2 = [SP value of water-soluble organic solvent A x volume fraction of water-soluble organic solvent A] + [water solubility SP value of organic solvent B × volume fraction of water soluble organic solvent B + · · · [SP value of water soluble organic solvent N × volume fraction of water soluble organic solvent N] + [SP value of water × water Volume fraction of] ..... formula (A)

  The above-mentioned SP value refers to what numerically expresses how easily each other melts. The SP value is expressed as a force of mutual attraction between molecules, that is, a square root of cohesive energy density CED (Cohesive Energy Density). In addition, said CED is the energy amount required to evaporate 1 mL of things.

The SP value can be calculated by the Fedors method using the following formula (B).
SP value (dissolution parameter) = (CED value) ^1/2 = (E / V) ^1/2 ··· Formula (B)
In the above formula (B), E is molecular cohesive energy (cal / mol), V is a molecular volume (cm ³ / mol), and the evaporation energy of the atomic group is Δei and the molar volume is Δvi, the following formula ( C) and formula (D).
E = ΣΔei ······ Formula (C) V = ΔΔvi ······ Formula (D)
There are various methods of calculating the SP value, but in the present invention, the method of Fedors generally used is used.

As data of the calculation method and evaporation energy Δei and molar volume Δvi of each atomic group, it is possible to use the data described in “Basic theory of adhesion” (published by Kouji Imoto, Chapter 5) it can.
As for those in which a —CF ₃ group or the like is not shown, R. F. Fedors, Polym. Eng. Sci. 14, 147 (1974).
For reference, when converting the SP value shown in the formula (B) to (J / cm ³ ) ^1/2 , convert 2.046 to SI unit (J / m ³ ) ^1/2 In that case, multiply by 2,046.

  In the present invention, only the water-soluble organic solvent and the water contained in an amount of 3% by mass or more based on the total amount of the aqueous ink are considered in the calculation of the SP value.

  In the mixed solution, the mass ratio (water-soluble organic solvent / water) between the content (mass%) of the water-soluble organic solvent and the content (mass%) of the water is preferably 0.5 or more and 2 or less. And 0.8 or more and 1.2 or less are more preferable.

-Water soluble organic solvent-
The water-soluble organic solvent is contained to prevent drying of the ink and to improve the dispersion stability.

  Examples of the water-soluble organic solvent include polyhydric alcohol compounds, polyhydric alcohol alkyl ether compounds, polyhydric alcohol aryl ether compounds, nitrogen-containing heterocyclic compounds, amide compounds, amine compounds, sulfur-containing compounds, propylene carbonate, ethylene carbonate Etc.

  Examples of the polyhydric alcohol compound include glycerin, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, and trilyl. Ethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, hexylene glycol, trimethylolethane, trimethylolpropane, 1,2,3-butanetriol, 1,2,4, -Butanetriol, 1,2,6-hexanetriol, petriol and the like. These may be used alone or in combination of two or more.

  Examples of the polyhydric alcohol alkyl ether compound include diethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether and the like. Be These may be used alone or in combination of two or more.

  Examples of the polyhydric alcohol aryl ether compounds include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether. These may be used alone or in combination of two or more.

  Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone and the like. It can be mentioned. These may be used alone or in combination of two or more.

Examples of the amide compound include acetamide, dimethylformamide, diethylacetamide and the like. These may be used alone or in combination of two or more.
Examples of the amine compound include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine. These may be used alone or in combination of two or more.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane and thiodiethanol. These may be used alone or in combination of two or more.
Among these, glycerin, diethylene glycol, 1,3-butanediol and 3-methyl-1,3-butanediol are preferred from the viewpoints of solubility and prevention of defective injection characteristics due to water evaporation, storage stability, and ejection stability. preferable.

  The content of the water-soluble organic solvent is preferably 20% by mass to 50% by mass, and more preferably 25% by mass to 35% by mass, based on the total amount of the aqueous ink.

-Water-
There is no restriction | limiting in particular as said water, According to the objective, it can select suitably, For example, pure waters, such as ion-exchange water, ultrafiltration water, reverse osmosis water, distilled water; ultrapure water, etc. are mentioned . These may be used alone or in combination of two or more. In addition, as SP value of the said water, it is 23.4 (cal / cm < ³ >) ^<1/2 >.

  The content of the water is preferably 60% by mass or less, and more preferably 20% by mass to 60% by mass, with respect to the total amount of the aqueous ink. When the content is 60% by mass or less, viscosity increase of the post-treatment liquid when water is evaporated, gelation, precipitation of insoluble matter and the like can be prevented.

<< Other ingredients >>
The other components are not particularly limited as long as they can be used in the aqueous ink, for example, sugar compounds and derivatives thereof; surfactants; foam inhibitors; carboxyl group-containing resins; Agents; polymer particles; pH adjusters; antiseptic and mildewproofing agents;

-Sugar compounds and derivatives thereof-
The sugar compound is contained to improve the drying resistance, and includes, for example, monosaccharide compounds, disaccharide compounds, oligosaccharide compounds (including trisaccharide compounds and tetrasaccharide compounds), polysaccharide compounds, derivatives thereof, and the like. Can be mentioned. Specifically, glucose, mannose, fructose, ribose, chylose, trehalose, mantotriose and the like can be mentioned. These may be used alone or in combination of two or more. In addition, a polysaccharide compound is a sugar of a broad sense, and means the thing containing the substance which exists widely in nature, such as alpha-cyclodextrin and a cellulose. Examples of the derivative of the sugar compound include reducing sugars of the sugar compound, oxidized sugars of the sugar compound, and the like. These may be used alone or in combination of two or more. Among these, sugar alcohols are preferable, and maltitol and sorbit are more preferable. The content of the sugar compound and the derivative thereof is preferably 0.1% by mass to 40% by mass, and more preferably 0.5% by mass to 30% by mass, with respect to the total amount of the aqueous ink.

-Surfactant-
The surfactant is not particularly limited, and may be appropriately selected from surfactants which do not impair the dispersion stability depending on the kind of coloring agent, the combination of a water-soluble organic solvent, a penetrant and the like according to the purpose. it can. As the surfactant, particularly when recording on a recording medium, a fluorine-based surfactant, a silicone type surfactant and the like can be mentioned from the viewpoint of low surface tension and high leveling ability. These may be used alone or in combination of two or more. Among these, fluorine surfactants are preferable.

--Fluorosurfactant--
As the fluorine-based surfactant, for example, a perfluoroalkylsulfonic acid compound, a perfluoroalkylcarboxylic acid compound, a perfluoroalkyl phosphoric acid ester compound, a perfluoroalkylethylene oxide adduct, and a perfluorinated ethylene carbonate compound, from the viewpoint of low foamability. Examples thereof include polyoxyalkylene ether polymer compounds having a fluoroalkyl ether group in a side chain. These may be used alone or in combination of two or more.

  Examples of the perfluoroalkylsulfonic acid compound include perfluoroalkylsulfonic acid and perfluoroalkylsulfonic acid salts. These may be used alone or in combination of two or more.

  Examples of the perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. These may be used alone or in combination of two or more.

  As said perfluoro alkyl phosphoric acid ester compound, perfluoro alkyl phosphoric acid ester, perfluoro alkyl phosphoric acid ester salt etc. are mentioned, for example. These may be used alone or in combination of two or more.

  As the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain, for example, a sulfuric acid ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, a side chain is a perfluoroalkyl ether group And salts of polyoxyalkylene ether polymers contained in the above. These may be used alone or in combination of two or more.

Counter ions of salts in the fluorine-based surfactant, for _{example, Li, Na, K, NH} 4, NH 3 CH 2 CH 2 OH, NH 2 (CH 2 CH 2 OH) 2, NH (CH 2 CH 2 OH) ₃ etc. ion is mentioned.

  As the fluorine-based surfactant, one appropriately synthesized or a commercially available product may be used. Examples of the commercially available product include Surfron series (S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145) manufactured by Asahi Glass Co., Ltd .; 3 M Japan Ltd. full-flood series (FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431); Megafuck made by DIC Corporation Series (F-470, F-1405, F-474); Zonyl TBS manufactured by Dupont, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR; -110, FT-250, FT-252, FT-400S, FT-150, FT-400SW; PF-151N manufactured by Omnova, etc. And the like. These may be used alone or in combination of two or more. Among these, fluorine-based surfactants represented by the following formula (i) are preferable.

  The fluorinated surfactant of the formula (i) does not contain perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), and is excellent in terms of global environmental pollution.

--Silicone type surfactant--
There is no restriction | limiting in particular as said silicone type surfactant, According to the objective, it can select suitably, For example, the thing which does not decompose | disassemble also at high pH is mentioned, Specifically, side chain modified polydimethylsiloxane, both End-modified polydimethylsiloxane, one-end modified polydimethylsiloxane, side-chain both-end modified polydimethylsiloxane are preferable, and from the viewpoint of exhibiting good properties as an aqueous surfactant, polyoxyethylene group as a modifying group, polyoxyethylene polyoxy Those having a propylene group are more preferred.

  As said silicone type surfactant, a polyether modified silicone type surfactant etc. are mentioned, for example. Among these, the compound which introduce | transduced the polyalkylene oxide structure into the Si part side chain of dimethylsiloxane is preferable.

As the silicone type surfactant, one synthesized appropriately may be used, or a commercially available product may be used.
Examples of the commercially available products include Big Chemie Japan Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., and the like, and examples of polyether-modified silicone compounds include Shin-Etsu Chemical Co., Ltd. Company-made KF-618, KF-642, KF-643 etc. are mentioned. These may be used alone or in combination of two or more.

--Other surfactants--
As surfactant other than the said fluorochemical surfactant and silicone type surfactant, anionic surfactant, nonionic surfactant, acetylene glycol surfactant, amphoteric surfactant, etc. are mentioned. These may be used alone or in combination of two or more.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, succinate sulfonate, laurate, salts of polyoxyethylene alkyl ether sulfate, and the like. These may be used alone or in combination of two or more.
Examples of the nonionic surfactant include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, and polyoxyethylene sorbitan fatty acid esters. These may be used alone or in combination of two or more.
Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octin-3,6-diol, and the like. And 5-dimethyl-1-hexyne-3-ol and the like. These may be used alone or in combination of two or more. As a commercial item of the said acetylene glycol type surfactant, Surfynol series (104, 82, 465, 485, TG) by Air Products Ltd. etc. are mentioned, for example. These may be used alone or in combination of two or more.
Examples of the amphoteric surfactant include lauryl amino pyropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, lauryl dimethyl amine oxide, myristyl dimethyl amine oxide, stearyl dimethyl amine oxide, dihydroethyl lauryl amine oxide And polyoxyethylene palm oil alkyldimethylamine oxide, dimethylalkyl (coconut) betaine, dimethyl lauryl betaine and the like. These may be used alone or in combination of two or more. As a commercial product of the amphoteric surfactant, for example, manufactured by Nikko Chemicals Co., Ltd., Japan Emulsion Co., Ltd., Nippon Catalyst Co., Ltd., Toho Chemical Industry Co., Ltd., Kao Co., Ltd., ADEKA Co., Ltd., Lion Co., Ltd. Products manufactured by Aoki Yushi Kogyo Co., Ltd., manufactured by Sanyo Chemical Industries Co., Ltd. These may be used alone or in combination of two or more.

  As the surfactant, one kind may be used alone, or two or more kinds may be used in combination, and even if one kind is not easily dissolved in the aqueous ink, two or more kinds may be mixed. In some cases, it can be solubilized and stably present.

  The content of the surfactant is preferably 0.01% by mass to 4% by mass, and more preferably 0.1% by mass to 1% by mass, with respect to the total amount of the aqueous ink. When the content is 0.01% by mass or more, the effect of adding a surfactant can be sufficiently exhibited, and when the content is 4% by mass or less, the permeability to the recording medium is appropriately maintained. In addition, it is possible to eliminate defects such as strike-through caused by penetrating more than necessary.

-Antifoam agent-
The foam inhibitor is contained in order to suppress the generation of air bubbles.
The surfactant activity of the surfactant containing the compound of the formula (i) or the like is very high, and even if a generally used silicone type foam inhibitor is added, once bubbles are generated. There is a problem that the bubbles remain without disappearing and a problem occurs. With respect to the above-mentioned problem, by containing a foam inhibitor, it is possible to suppress the occurrence of discharge failure and the like when discharging by the discharge head.

  Examples of the foam inhibitor include N-octyl-2-pyrrolidone, 2,4,7,9-tetramethyldecane-4,7-diol, 2,5,8,11-tetramethyldodecane-5,8. -Diol etc. are mentioned. These may be used alone or in combination of two or more. By using at least one of the above-mentioned foam inhibitors in combination with a surfactant such as formula (i), the generation of air bubbles can be suppressed, and the problems caused by air bubbles can be eliminated.

  As the content of the foam inhibitor, the total content of the content (mass%) of the surfactant and the content (mass%) of the foam inhibitor is preferably 40 mass% or less based on the total amount of the aqueous ink, 30 mass% or less is more preferable. Foaming of aqueous ink can be suppressed as the said content is 40 mass% or less.

-Carboxyl group-containing resin-
The carboxyl group-containing resin is contained in order to react with the crosslinking agent in the post-treatment liquid, cause aggregation of the pigment on the recording medium, and improve the image quality. Moreover, even when the post-treatment liquid is not present, the scratch resistance can be improved by containing the carboxyl group-containing resin.

Examples of the carboxyl group-containing resin include maleic acid resin, styrene-maleic acid resin, rosin modified maleic acid resin, alkyd resin, modified alkyd resin and the like. These may be used alone or in combination of two or more.
As the carboxyl group-containing resin, one appropriately synthesized or a commercially available product may be used. As a commercial item of the said carboxyl group-containing resin, the Marquide series made from Arakawa Chemical Industries, Ltd., the Harimac series made by Harima Chemicals Co., Ltd., the Hariftal series etc. are mentioned, for example.

  As a form of addition of the carboxyl group-containing resin, a pigment which is a colorant may be added in a form in which it is included (microcapsulated) with a carboxyl group-containing resin, or a colorant may be added in a dispersed form .

-Penetration agent-
The penetrant is contained to increase the penetration speed to the recording medium and to prevent bleeding.
Examples of the penetrant include polyol compounds having 8 to 11 carbon atoms and glycol ether compounds. These may be used alone or in combination of two or more.
The penetrant has an effect of accelerating the penetration speed into the recording medium and preventing bleeding, and has a boiling point higher than that of water, and is 0.1 mass% or more and 4.5 mass% or less in water at 25 ° C. It is a partially water-soluble compound having a solubility of

Examples of the polyol compound having 8 to 11 carbon atoms include 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, and 1,2-octanediol. Be These may be used alone or in combination of two or more.
Examples of the glycol ether compound include polyhydric alcohol alkyl ether compounds and polyhydric alcohol aryl ether compounds. These may be used alone or in combination of two or more.
Examples of polyhydric alcohol alkyl ether compounds include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. . These may be used alone or in combination of two or more.
Examples of polyhydric alcohol aryl ether compounds include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether. These may be used alone or in combination of two or more.

  The content of the penetrant is preferably 0.1% by mass to 10% by mass, and more preferably 0.5% by mass to 5% by mass, with respect to the total amount of the aqueous ink.

-Polymer particles-
The polymer particles are contained to improve the film forming property. The film-forming property refers to the property of forming a resin film when the water of the aqueous emulsion is evaporated when the polymer particles are dispersed in water to form an aqueous emulsion.
When the polymer particles are contained, when the volatile component in the aqueous ink evaporates, the polymer particles can form a film, and the colorant in the aqueous ink can be strongly fixed to the recording medium. . Thereby, an image excellent in abrasion resistance and water resistance can be realized.

  The minimum film-forming temperature of the polymer particles is preferably 30 ° C. or less, more preferably 10 ° C. or less, from the viewpoint of forming a film at room temperature. In addition, when the polymer emulsion obtained by dispersing polymer particles in water was thinly cast on a metal plate such as aluminum and the temperature was raised, the minimum film-forming temperature was transparent and continuous. The lowest temperature at which a film is formed. Examples of the polymer particles include Landy PL series manufactured by Miyoshi Yushi Co., Ltd.

  The volume average particle diameter of the polymer particles is preferably 5 nm or more and 200 nm or less, and more preferably 10 nm or more and 100 nm or less. The volume average particle diameter can be measured using a particle size distribution measuring apparatus (trade name: Microtrac UPA, manufactured by Nikkiso Co., Ltd.) or the like.

  Examples of the structure of the polymer particles include single particles. For example, when an alkoxysilyl group is contained in the emulsion particles, the emulsion particles come into contact with the remaining water as the emulsions fuse together due to evaporation of water in the process of forming a coating, and are hydrolyzed to form silanol groups. In addition, when the silanol group remains, the alkoxysilyl group or silanols react with each other to form a strong crosslinked structure by siloxane bond. When a reactive functional group is allowed to coexist in the polymer fine particles, the functional group can be reacted at the time of film formation to form a network structure even without adding a curing agent.

  In addition, polymer particles having a core-shell structure comprising a core portion and a shell portion surrounding the core portion can also be used. The core-shell structure refers to a form in which two or more kinds of polymers having different compositions are phase separated and present in particles. As the polymer particle having a core-shell structure, not only a form in which the shell part completely covers the core part, but also a part in which the core part is covered may be used. In addition, a part of the polymer of the shell portion may form a domain or the like in the core particle. Furthermore, it may have a multilayer structure of three or more layers including one or more layers having different compositions, between the core portion and the shell portion.

  The polymer particles can be obtained by a known method such as emulsion polymerization of unsaturated vinyl monomer (unsaturated vinyl polymer) in water in the presence of a polymerization catalyst and an emulsifier.

  The content of the polymer particles is preferably 0.5% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the aqueous ink.

-PH adjuster-
The colorant particles (composite pigment particles) in which the inorganic particles are coated with the colorant tend to exhibit acidity when they are mixed and dispersed in water together with the anionic dispersant. The surface of the composite pigment dispersed in a medium such as water is negatively charged because it is encased in an anionic dispersant, but the inside is positively charged because the entire ink exhibits acidity. The negative charge on the particle surface is likely to be neutralized. In the above-mentioned state, the dispersed particles coagulate to cause ejection failure. Therefore, it is preferable to stabilize the dispersion state and stabilize the ejection by adding an pH adjuster and maintaining the alkalinity.

  The pH of the aqueous ink is preferably 9 or more and 11 or less. By setting the pH to 9 or more and 11 or less, corrosion of members such as an aqueous ink application unit can be prevented. The pH adjuster is preferably added to the kneaded dispersion together with additives such as a wetting agent and a penetrant rather than being added when the pigment is kneaded and dispersed in water together with the dispersant. This is because the addition of the pH adjuster may break the dispersion.

Examples of the pH adjuster include alcohol amine compounds, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates and the like. These may be used alone or in combination of two or more.
Examples of the alcohol amine compound include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol and the like. These may be used alone or in combination of two or more.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like. These may be used alone or in combination of two or more.
Examples of the ammonium hydroxide include ammonium hydroxide and quaternary ammonium hydroxide. These may be used alone or in combination of two or more.
Examples of the phosphonium hydroxide include quaternary phosphonium hydroxide.
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate and potassium carbonate. These may be used alone or in combination of two or more.

-Antiseptic and fungicide-
Examples of the antiseptic and fungicides include benzotriazole, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol and the like. These may be used alone or in combination of two or more.

-Rust inhibitor-
Examples of the antirust agent include acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, and dicyclohexyl ammonium nitrite. These may be used alone or in combination of two or more.

<Post-treatment liquid>
The post-treatment liquid is contained to improve the gloss of the image.
The post-treatment liquid contains a mixed solution of at least one of a urethane resin and an acrylic resin, a water-soluble organic solvent and water, and further contains, if necessary, a wax, a self-crosslinking resin, and other components. .

<< Mixed solution >>
The mixed solution contains a water-soluble organic solvent and water. The mixed solution refers to one containing a water-soluble organic solvent and water, and also includes one which is classified as a penetrant, a foam inhibitor, etc. in terms of function.

The SP value of the mixed solution in the post-treatment liquid is preferably 10 (cal / cm ³ ) ^1/2 or more and 30 (cal / cm ³ ) ^1/2 or less, and 12 (cal / cm ³ ) ^1/2 or less. More than 19.0 (cal / cm ³ ) ^1/2 or less is more preferable.

As SP value in the said mixed solution of the said water-soluble organic solvent in the said post-processing liquid and the said water, with respect to SP value in the said mixed solution of the said water-soluble organic solvent in the said aqueous ink and the said water 1. 5 (cal / cm ³ ) ^1/2 or more lower, 7.5 (cal / cm ³ ) ^1/2 or lower lower, preferably 3.0 (cal / cm ³ ) ^1/2 or more 5.0 (cal / cm ³ ) It is more preferable that cm ³ ) ^1/2 or less.
The SP value of the mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is the SP value of the SP in the mixed solution of the water-soluble organic solvent and the water in the aqueous ink. When the value is lower than 1.5 (cal / cm ³ ) ^1/2 or more, the gloss of the image can be obtained when the post-processing liquid is applied to the surface of the fixed image, and the post-processing liquid is not determined. Even when applied to the surface of the image in the adhered state, mixing of the post-processing liquid into the unfixed image can be suppressed, and the post-processing liquid can form a coating film uniformly on the surface of the image, The glossiness of the image can be imparted. In addition, when it is lower than 7.5 (cal / cm ³ ) ^1/2 or less, the film thickness of the coating film formed by the post-treatment liquid becomes large, and the abrasion resistance of the image can be improved. The SP value in the water-soluble organic solvent in the post-treatment liquid, the SP value in the water, and the SP value in the mixed solution of the water-soluble organic solvent and the water are the water-soluble organic materials in the aqueous ink. The SP value in the solvent, the SP value in the water, and the SP value in the mixed solution of the water-soluble organic solvent and the water can be calculated similarly.

  In the present invention, only the water-soluble organic solvent and the water contained in an amount of 3% by mass or more based on the total amount of the post-treatment liquid are considered in the calculation of the SP value.

  In the mixed solution, the mass ratio (water-soluble organic solvent / water) between the content (mass%) of the water-soluble organic solvent and the content (mass%) of the water is preferably 0.5 or more and 2 or less. And 0.8 or more and 1.2 or less are more preferable.

-Water soluble organic solvent-
Examples of the water-soluble organic solvent include 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, diethylene glycol monoisopropyl ether, diethylene glycol monoisobutyl ether, tripropylene glycol methyl ether, 1-methoxy- Preferred examples include 2-propanol, a compound represented by the following formula (I), a compound represented by the following formula (II), and a compound represented by the following formula (III). These may be used alone or in combination of two or more. By containing the water-soluble organic solvent in the post-treatment liquid, the SP value in the mixed solution in the post-treatment liquid can be made lower than the SP value in the mixed solution in the aqueous ink.

  The post-treatment liquid may be, for example, a method of discharging from a recording head, and from the viewpoint of dischargeability from the recording head and maintainability, temperature 23 ° C., relative humidity 80 other than the water-soluble organic solvent. % Polyhydric alcohol whose equilibrium water content in the environment is 30% by mass or more, a compound represented by the following general formula (IV), a compound represented by the following general formula (V), a compound represented by the following general formula (VI) It is preferable to contain These may be used alone or in combination of two or more.

前記式（ＩＶ）中、Ｒ^１は炭素数１以上２以下のアルキル基を示し、Ｒ^２は水素原子、炭素数１以上８以下のアルキル基、環状アルキル基又は芳香環を示す。

In formula (IV), R ¹ represents an alkyl group having 1 to 2 carbon atoms, and R ² represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group or an aromatic ring.

前記式（Ｖ）中、Ｒ^３は水素原子又は炭素数１以上２以下のアルキル基を示し、Ｒ^４は炭素数１以上４以下のアルキル基を示す。

In the formula (V), R ³ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, R ⁴ represents an alkyl group having 1 to 4 carbon atoms.

前記式（ＶＩ）中、Ｒ^５及びＲ^６は炭素数１以上８以下のアルキル基を示す。

In the formula (VI), ^{R 5} and ^{R 6} is an alkyl group having 1 to 8 carbon atoms.

  Examples of the polyhydric alcohol include 1,3-butanediol (melting point: 203 ° C. or more and 204 ° C. or less, equilibrium water content: 35% by mass), 1,2,3-butanetriol (melting point: 175 ° C./33 hPa, Equilibrium water content: 38% by mass), 1,2,4-butanetriol (melting point: 190 ° C. to 191 ° C./24 hPa, equilibrium water content: 41% by mass), glycerin (melting point: 290 ° C., equilibrium water content: 49 Mass%), diglycerin (melting point: 270 ° C./20 hPa, equilibrium moisture content: 38 mass%), diethylene glycol (melting point: 245 ° C., equilibrium moisture content: 43 mass%), triethylene glycol (melting point: 285 ° C., equilibrium moisture Amount: 39% by mass), tetraethylene glycol (melting point: 324 ° C. or more and 330 ° C. or less, equilibrium water content: 37% by mass) and the like. These may be used alone or in combination of two or more. Among these, glycerin and 1,3-butanediol are preferable.

  As the equilibrium water content (%), the temperature and humidity in the desiccator are maintained at a temperature of 23 ± 1 ° C. and a relative humidity of 80 ± 3% using a potassium chloride / sodium chloride saturated aqueous solution, and each water-soluble organic solvent is contained in this desiccator The petri dish which weighed 1 g of each was put into the petri dish, and after storing for 24 hours, the amount of water which equilibrates was measured and it computed by the following formula (E).

  A water-soluble organic solvent other than the water-soluble organic solvent of the post-treatment liquid and a wetting agent can be used in combination. Specific examples thereof include polyhydric alcohol compounds, polyhydric alcohol alkyl ether compounds, polyhydric alcohol aryl ether compounds, nitrogen-containing heterocyclic compounds, amide compounds, amine compounds, sulfur-containing compounds, propylene carbonate, ethylene carbonate and the like. Be These may be used alone or in combination of two or more.

  Examples of the polyhydric alcohol compound include 3-methyl-1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene And glycol, polypropylene glycol, hexylene glycol, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, petriol 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, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether and the like. Be These may be used alone or in combination of two or more.

  Examples of the polyhydric alcohol aryl ether compounds include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether. These may be used alone or in combination of two or more.

Examples of the amine compound include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine. These may be used alone or in combination of two or more.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane and thiodiethanol. These may be used alone or in combination of two or more.

  As content of the said water-soluble organic solvent, 20 mass% or more and 40 mass% or less are preferable with respect to post-processing liquid whole quantity, and 20 mass% or more and 30 mass% or less are more preferable. When the content is 20% by mass or more, the flowability of the post-processing liquid can be secured even when the water in the post-processing liquid is evaporated, and when it is 30% by mass or less, the recording head discharges It can be adjusted to the viscosity required to

-Water-
As said water, the thing similar to the said water-based ink can be used.

<< Resin >>
The said resin is contained in order to improve the glossiness of an image, and the abrasion resistance of an image.

  The resin contains at least one of a urethane resin and an acrylic resin, and further contains other resins as necessary.

When using 2 or more types together as said resin, at least 2 types from which the volume average particle diameter of the said resin differs is preferable. Specifically, one having a volume average particle diameter (D50) of the resin larger than a volume average particle diameter (D50) of a colorant used in the aqueous ink, and a volume average particle diameter (D50) of the resin It is preferable to contain at least one kind of each of the small ones.
When a resin having a volume average particle diameter smaller than the volume average particle diameter of the colorant used in the aqueous ink is used, the resin can penetrate into small gaps between the colorants, and the image scratch resistance is improved. It can be improved. When a resin having a volume average particle size larger than the volume average particle size of the colorant used in the aqueous ink is used, the smoothness is improved by uniformly forming a coating film on the surface of the aqueous ink. The gloss can be improved. In addition, the binding property between the resin and the recording medium can be improved physically, the resin can not be easily removed, and the abrasion resistance can be improved. The glossiness of the image can be adjusted by controlling the volume average particle diameter of the resin and the smoothness at the time of film formation.

  The volume average particle diameter (D50) of the resin is preferably 10 nm or more and 300 nm or less. When the volume average particle diameter (D50) is 10 nm or more, the viscosity of the resin does not become too high, and the discharge stability in the recording head can be improved, and when it is 300 nm or less, the resin image forming apparatus Nozzle clogging can be suppressed. The volume average particle diameter can be measured using a particle size distribution measuring apparatus (trade name: Microtrac UPA, manufactured by Nikkiso Co., Ltd.) or the like.

The SP value of at least one of the urethane resin and the acrylic resin in the post-treatment liquid is preferably 6 (cal / cm ³ ) ^1/2 or more and 34 (cal / cm ³ ) ^1/2 or less, and 8 (cal / cm ³ ) cm ³ ) ^1/2 or more and 23 (cal / cm ³ ) ^1/2 is more preferable.

The difference between the SP value of at least one of the urethane resin and the acrylic resin in the post-treatment liquid and the SP value of the mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is 4 (cal / Cm ³ ) ^1/2 or less is preferable. The “difference between the SP value of at least one of the urethane resin and the acrylic resin in the post-treatment liquid and the SP value of the mixed solution of the water-soluble organic solvent and water in the post-treatment liquid” When one or more kinds of urethane resins are contained, or when one or more kinds of acrylic resins are contained, or when one or more kinds of urethane resins and acrylic resins are used in combination, any one of them may be used. It means the difference between the SP value of various resins and the SP value of the mixed solution of water-soluble organic solvent and water in the post-treatment liquid, and at least one of the above differences is 4 (cal / cm ³ ) ^1/2 It is enough if it is the following. In other words, the difference between the SP value in all types of resins contained in the post-treatment liquid and the SP value in the mixed solution of the water-soluble organic solvent and water in the post-treatment liquid is 4 (cal / cm ³ ) ^1/2 It does not have to be
The difference between the SP value of at least one of the urethane resin and the acrylic resin in the post-treatment liquid and the SP value of the mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is 4 (cal / cm ^3). The image glossiness can be improved if it is ^1/2 or less.

The method of calculating the SP value in the resin is different from the method of calculating the SP value in the water-soluble organic solvent, the water, and the mixed solution, and is a value measured by a turbidity point titration method. W. SUH, J.L. M. Calculated using the CORBETT equation.
SP value of resin = {(V _ml ) ^1/2 × δ _H + (V _mh ) ^1/2 × δ _D } / {(V _ml ) ^1/2 + (V _mh ) ^1/2 }
Here, V _ml , V _mh , δ _H and δ _D are the titrations at the turbidity point when n-hexane is added to a solution of 0.5 g (solid content) of resin in 10 mL of acetone at a measurement temperature of 20 ° C. The amount H (mL) and the titration amount D (mL) at the turbidity point when deionized water is added while dissolving 0.5 g of resin (solid content) in 10 mL of acetone at a measurement temperature of 20 ° C. It is a value calculated by applying to a formula.
V _ml = 74.4 x 130.3 / {(1-V _H ) x 130.3 + V _H x 74.4}
V _mh = 74.4 × 18 / {(1−V _D ) × 18 + V _D × 74.4}
V _H = H / (10 + H)
V _D = D / (10 + D)
δ _H = 9.75 × 10 / (10 + H) + 7.24 × H / (10 + H)
δ _D = 9.75 × 10 / (10 + D) + 23.43 × D / (10 + D)
The molecular volume (mL / mol) of each solvent is acetone: 74.4, n-hexane: 130.3, deionized water: 18, and the SP value of each solvent is acetone: 9.75, n -Hexane: 7.24, deionized water: 23.43. Moreover, the unit of SP value of obtained resin is (cal / cm < ³ >) ^<1/2 >.

-Urethane resin-
The urethane resin is preferably an anionic self-emulsifying urethane resin from the viewpoint of dispersion stability, and an anion from the viewpoint of film forming ability, strength, and bendability when the post-treatment liquid is applied to the image forming portion. Self-emulsifying ether type urethane resin is more preferable.

  As an acid value of the said urethane resin, 10 mgKOH / g or more and 100 mgKOH / g or less are preferable, and 25 mgKOH / g or more and 80 mgKOH / g or less are more preferable. If the acid value is 10 mg KOH / g or more, rapid aggregation can not occur and a uniform film can be formed, and if 100 mg KOH / g or less, excess water can be prevented from being contained. It is possible to form a uniform film and to improve the scratch resistance of the image. The acid value refers to the number of mg of potassium hydroxide required to neutralize free fatty acids and other acidic substances contained in 1 g of fats and oils such as fats and oils or waxes. As the measurement of the acid value, a fat sample of a mass corresponding to the acid value of fat is measured, dissolved in a neutral benzene alcohol solution, etc., and titrated with an alcoholic potassium hydroxide solution using phenolphthalein as an indicator. It can be calculated according to JIS K 0070-1992.

The SP value of the urethane resin is preferably 6 (cal / cm ³ ) ^1/2 or more and 34 (cal / cm ³ ) ^1/2 or less, and 8 (cal / cm ³ ) ^1/2 or more 23 (cal / cm) ³ ) ^1/2 or less is more preferable.

  As a glass transition point of the said urethane resin, -50 degreeC or more and 150 degrees C or less are preferable, and -10 degreeC or more and 30 degrees C or less are more preferable. When the glass transition temperature is -50 ° C or higher, the coating film is too soft to reduce the scratch resistance of the image, and when the glass transition temperature is 150 ° C or lower, sufficient scratch resistance of the image can be obtained. . The glass transition point can be measured by differential scanning calorimetry (DSC) or TMA thermomechanical analysis (TMA).

  As minimum film-forming temperature (MFT) of the said urethane resin, 25 degrees C or less is preferable. When the minimum film forming temperature (MFT) is 25 ° C. or less, binding of recording medium fibers can automatically proceed without heating or drying the recording medium on which an image is formed. The minimum film-forming temperature is defined by thinly casting aqueous emulsion particles obtained by dispersing urethane resin particles in water on a metal plate such as aluminum, and a transparent continuous film when the temperature is raised. The lowest temperature to be formed.

  As the urethane resin, a commercially available product can be used, and as the commercially available product, for example, Permarine series manufactured by Sanyo Chemical Industries, Ltd., W5661 manufactured by Mitsui Chemicals, Inc., XW-75-W932, Ltd. Examples include SF460S manufactured by NUC. Moreover, you may use what grafted aqueous | water-based urethane resin and acrylic resins like WEM-3000 by Taisei Fine Chemical Co., Ltd. etc. FIG. These may be used alone or in combination of two or more.

-Acrylic resin-
Among the above-mentioned acrylic resins, acrylic silicone resins are preferable from the viewpoint of strength and glossiness when the post-treatment liquid is applied to the image forming portion.

The SP value of the acrylic resin is preferably 6 (cal / cm ³ ) ^1/2 or more and 34 (cal / cm ³ ) ^1/2 or less, and 8 (cal / cm ³ ) ^1/2 or more 23 (cal / cm). ³ ) ^1/2 or less is more preferable.

  As the acrylic resin, commercially available products can be used, and as the commercially available products, KP-543, KP-545, KP-549 manufactured by Shin-Etsu Chemical Co., Ltd .; AQ-914 manufactured by Daicel Finechem Co., Ltd., AQ- ASi-91, AQ-4790, etc. are mentioned. These may be used alone or in combination of two or more.

  As content of the said resin, 10 mass% or more and 40 mass% or less are preferable with respect to post-processing liquid whole quantity, and 20 mass% or more and 30 mass% or less are more preferable.

<< Waxing >>
The wax is contained to impart slipperiness to the image area.

  Examples of the wax include polyethylene type wax and carnauba wax from the viewpoint of film formability and slipperiness. These may be used alone or in combination of two or more.

  The melting point of the wax is preferably 80 ° C. or more and 140 ° C. or less, and more preferably 100 ° C. or more and 140 ° C. or less. When the melting point is 80 ° C. or more, the wax is less likely to melt or coagulate excessively even in a room temperature environment, and the storage stability of the post-treatment liquid can be maintained, and when the melting point is 140 ° C. or less Even under the environment, the wax can be sufficiently melted to improve the slipperiness of the post-treatment liquid.

  The volume average particle diameter (D50) of the wax is preferably 0.01 μm or more, and more preferably 0.01 μm or more and 0.1 μm or less. When the volume average particle diameter (D50) is 0.01 μm or more, the wax particles are easily oriented on the surface of the post-treatment liquid, and the post-treatment liquid can be provided with slipperiness. The volume average particle diameter can be measured using a particle size distribution measuring apparatus (trade name: Microtrac UPA, manufactured by Nikkiso Co., Ltd.) or the like.

A commercially available product can be used as the polyethylene type wax, and examples of the commercially available product include Hitec series manufactured by Toho Chemical Industry Co., Ltd., AQUACER series manufactured by Big Chemie Japan Co., Ltd., and the like. These may be used alone or in combination of two or more.
A commercially available product can be used as the carnauba wax, and examples of the commercially available product include Cellosol 524 and Trasol CN manufactured by Chukyo Yushi Co., Ltd. These may be used alone or in combination of two or more.

  As content of the said wax, 1 mass% or more and 10 mass% or less are preferable with respect to post-processing liquid whole quantity, and 1 mass% or more and 5 mass% or less are more preferable.

<< Self-crosslinking resin >>
The self-crosslinking resin may be contained to form a crosslinked structure between the aqueous ink and the post-treatment liquid.

Examples of the self-crosslinking resin include heat-reactive resins.
Examples of the heat-reactive resin include self-crosslinking resins having an isocyanate group. The self-crosslinking resin having an isocyanate group is a heat-reactive resin having a block isocyanate group in a urethane skeleton, and the block part bonded to the isocyanate group is dissociated by heat to become an active isocyanate group, Can cause a self-crosslinking reaction to form a three-dimensional network structure. At the same time, the active isocyanate group also reacts with the urethane resin in the post-treatment liquid, whereby the chain length of the three-dimensional network structure is extended, and a denser three-dimensional network structure can be formed.

  Drying by heat after application of the post-treatment liquid activates the isocyanate groups in the self-crosslinking resin contained in the post-treatment liquid, and crosslinks with the self-crosslinking and urethane resin to form a three-dimensional network structure. It can be formed. Therefore, even if the post-processing liquid is applied to the surface of the image in a state where the image formed by discharging the aqueous ink is not fixed, the post-processing liquid is less likely to enter the image and uniform on the surface of the aqueous ink A coating can be formed, and the gloss of the image and the abrasion resistance of the image can be improved.

  A commercially available product can be used as the self-crosslinking resin having an isocyanate group, and examples of the commercially available product include Elastron series manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

  In addition to the self-crosslinking resin, a cross-linking agent that crosslinks with the carboxyl group-containing resin in the aqueous ink can be contained in the post-treatment liquid to form the same three-dimensional network structure as described above. .

  From the viewpoint of reactivity, examples of the crosslinking agent include water-soluble oxazoline group-containing polymers and carbodiimide group-containing polymers. These may be used alone or in combination of two or more.

Examples of the water-soluble oxazoline group-containing polymer include a resin having an oxazoline group and fine particles having an oxazoline group adsorbed on the surface.
A commercial item can be used as resin which has the said oxazoline group, As said commercial item, K-2000 series made from Nippon Shokubai Co., Ltd., WA series, RPS series, RAS series etc. are mentioned. These may be used alone or in combination of two or more.

The fine particles having the oxazoline group adsorbed on the surface may be organic fine particles or inorganic fine particles. As the organic fine particles, commercially available products can be used, and as the commercially available products, ME series manufactured by Soken Chemical Co., Ltd., Julimer MB series manufactured by Nippon Junyaku Co., Ltd., Tospearl manufactured by Toshiba Silicone Co., Ltd. Series, Microgel series manufactured by Nippon Paint Co., Ltd., pull-on series manufactured by Asahi Glass Co., Ltd., and the like. These may be used alone or in combination of two or more. A commercial item can be used as said inorganic fine particle, As said commercial item, the titania series by Idemitsu Kosan Co., Ltd., aluminum oxide C by Nippon Aerosil Co., Ltd., etc. are mentioned. These may be used alone or in combination of two or more.
A commercially available product can be used as the carbodiimide group-containing polymer, and examples of the commercially available product include Carbodilite Series manufactured by Nisshinbo Chemical Co., Ltd.

  The content of the self-crosslinking resin is preferably 1% by mass to 10% by mass, and more preferably 2% by mass to 4% by mass, with respect to the total amount of the post-treatment liquid. When the content is 1% by mass or more, the gloss of the image due to the crosslinking reaction and the abrasion resistance of the image can be improved, and when the content is 10% by mass or less, the viscosity of the post-treatment liquid is appropriately The adjustment can be made, and the discharge stability from the recording head can be improved.

<< Other ingredients >>
The other components are not particularly limited as long as they can be used in the post-treatment liquid, for example, surfactants, foam inhibitors, pH adjusters, preservatives, fungicides, rust inhibitors Etc.

-Surfactant-
The surfactant is contained to lower the surface tension of the post-treatment liquid.
By containing the surfactant, the recording medium can be appropriately wettable, the penetration speed into the recording medium can be increased, and problems such as the abrasion resistance and the bleeding of the image can be improved.

  Examples of the surfactant include surfactants having a fluoroalkyl group. Examples of the surfactant having a fluoroalkyl group include a compound represented by the following formula (i), a polyoxyalkylene alkyl ether, and a polyether-modified siloxane copolymer.

なお、上記式（ｉ）で示される化合物はパーフルオロオクタンスルホン酸（ＰＦＯＳ）及びパーフルオロオクタン酸（ＰＦＯＡ）を含有しておらず、地球環境汚染の点から優れている。

The compound represented by the above formula (i) does not contain perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), and is excellent in terms of global environmental pollution.

  A commercial item can be used as a compound shown by said Formula (i), As a commercial item, brand name: Unidyne DSN-403N (made by Daikin Industries, Ltd.) etc. is mentioned.

  As content of the said surfactant, 0.01 mass% or more and 4 mass% or less are preferable with respect to post-processing liquid whole quantity, 0.1 mass% or more and 1 mass% or less are more preferable. When the content is 0.01% by mass or more, the effect of adding a surfactant can be sufficiently exhibited, and when the content is 4% by mass or less, the permeability to the recording medium is appropriately maintained. In addition, it is possible to eliminate defects such as strike-through caused by penetrating more than necessary.

-Antifoam agent-
As the foam inhibitor, the same one as the foam inhibitor used for aqueous ink can be used.

-PH adjuster-
As said pH adjuster, the thing similar to the pH adjuster used for aqueous ink can be used.

<< Recording medium >>
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, general purpose printing paper etc. are used suitably. Can.

(ink cartridge)
The cartridge contains the post-treatment liquid and the aqueous ink in a container, and further includes other members appropriately selected as necessary.

  The container is not particularly limited, and the shape, structure, size, material and the like can be appropriately selected according to the purpose. For example, a container made of plastic, an ink bag formed of an aluminum laminate film, etc. And the like.

  Next, the ink cartridge will be described with reference to FIGS. 5 and 6. Here, FIG. 5 is a view showing an example of the ink cartridge of the present invention, and FIG. 6 is a view including the case (outer case) of the ink cartridge of FIG.

  As shown in FIG. 5, the ink is filled into the ink bag 241 from the ink inlet 242 and evacuated, and then the ink inlet 242 is closed by fusion. In use, the needle of the apparatus main body is pierced through the ink discharge port 243 made of a rubber member to supply the ink to the apparatus. The ink bag 241 is formed of a packaging member such as an air-impermeable aluminum laminate film. As shown in FIG. 6, the ink bag 241 is usually housed in a plastic cartridge case 244, and is detachably mounted on an image forming apparatus as an ink cartridge 240 and used.

  Also, if the treatment liquid is put in the ink cartridge 240 instead of the ink and used as a cartridge for the treatment liquid, it can be detachably mounted on various image forming apparatuses like the ink cartridge.

(Image forming method and image forming apparatus)
The image forming method includes an image forming step of applying a stimulus and discharging the aqueous ink to record an image on a recording medium, and a post-processing step of applying a post-processing liquid on the surface on which the aqueous ink is discharged. And.
The image forming apparatus is an image forming unit that applies a stimulus and discharges the aqueous ink to record an image on a recording medium, and a post-processing unit that applies post-processing liquid to the surface on which the aqueous ink is discharged. And.

<Image Forming Process and Image Forming Means>
The image forming step is a step of applying a stimulus to the aqueous ink and ejecting the aqueous ink to form an image.
The image forming unit is a unit that applies a stimulus to the aqueous ink and discharges the aqueous ink to form an image.

  There is no restriction | limiting in particular as said stimulation, According to the objective, it can select suitably, For example, heat (temperature), a pressure, a vibration, light, etc. are mentioned. These may be used alone or in combination of two or more. Among these, heat and pressure are suitably mentioned.

  As a mode of discharge of the ink used for the image forming set, for example, a piezoelectric element is used as a pressure generating means for pressing the ink in the ink flow path to deform the diaphragm forming the wall surface of the ink flow path So-called piezo method (see, for example, Japanese Patent Publication No. 2-51734) that changes the volume in the ink flow path to eject ink droplets (for example, see Japanese Patent Publication No. 2-51734); So-called thermal system (see, for example, JP-B-61-59911); a diaphragm for forming a wall surface of the ink channel and an electrode are disposed opposite to each other, and a static circuit generated between the diaphragm and the electrode An electrostatic method (see, for example, Japanese Patent Laid-Open No. Hei 6-71882) or the like which discharges ink droplets by changing the volume in the ink flow path by deforming the diaphragm with electric power. It is.

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

<Process liquid application means and process liquid application process>
As the treatment liquid process, a method of applying the post-treatment liquid uniformly on the surface on which the aqueous ink is discharged may be used, and there is no particular limitation.
As the processing liquid means, there may be used an application means for uniformly applying the post-treatment liquid on the surface on which the aqueous ink is discharged, and there is no particular limitation.

  Examples of the application method include an inkjet method, blade coating method, gravure coating method, gravure offset coating method, bar coating method, roll coating method, knife coating method, air knife coating method, comma coating method, U comma coating method, AKKU Coating methods, smoothing coating methods, microgravure coating methods, reverse roll coating methods, 4 to 5 roll coating methods, dip coating methods, curtain coating methods, slide coating methods, die coating methods, etc. may be mentioned.

  Although the post-processing step and the post-processing means are performed on the image on which the surface of the image formed by discharging the aqueous ink is sufficiently fixed, the surface of the unfixed image is Even if done, the gloss of the image can be improved. In addition, it is preferable to provide a drying process and a drying unit as necessary for the recording medium subjected to the treatment. As the drying process and the drying means, the recording medium can be dried by a roll heater, a drum heater or warm air.

  The drying temperature can be changed according to the type and amount of the water-soluble organic solvent contained in the aqueous ink, and the minimum film forming temperature of the resin emulsion to be added, and further according to the type of the recording medium to be recorded. You can even change it.

  The drying temperature is preferably high from the viewpoint of drying property and film formation 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 more and 120 ° C. or less, damage to the recording medium due to heat can be prevented, and occurrence of non-ejection due to warming of the ink head can be suppressed.

Wet adhesion amount to the recording medium in the image forming apparatus for the post-treatment liquid in the post-treatment process is preferably intended to achieve 0.1 g / m ² or more 30.0 g / m ² or less of the range, 0. 2 g / m ² or more and 10.0 g / m ² or less is more preferable. When the wet adhesion amount is 0.1 g / m ² or more, the image quality (image density, saturation, color bleed, character bleeding and white spots) can be improved, and it is 30.0 g / m ² or less If it is present, the texture of the plain paper can be prevented from being impaired, and curling can be suppressed.

  The image forming apparatus comprises an image forming unit for forming an image by discharging an aqueous ink onto the surface of a recording medium, a storage unit for storing a post-processing liquid, and an image forming unit after the image formation by the image forming unit. And post-processing means for processing the surface. In addition, the image forming means has at least an ink applying means, and may have other means, for example, a stimulus generating means, a control means, etc., as required.

FIG. 1 shows a schematic view (side view) of an example of the image forming apparatus according to the present invention.
In the image forming apparatus 101, head maintenance is performed corresponding to the head units 110K, 110C, 110M, and 110Y in which the heads that discharge aqueous ink are accumulated, and the head units 151 that discharge the post-processing liquid. Maintenance unit 111K, 111C, 111M, 111Y, maintenance unit (not shown), ink cartridge 107K, 107C, 107M, 107Y for supplying ink and post-treatment liquid cartridge (not shown) The sub ink tanks 108 K, 108 C, 108 M and 108 Y for supplying ink at various pressures, and a sub tank for a post-processing liquid (not shown) are provided.

The conveyance belt 113 sucks and conveys the recording medium 114 by the suction fan 120, the conveyance rollers 119 and 121 supporting the conveyance belt 113, and the tension roller 115 and conveyance belt 113 control the conveyance belt 113 to maintain appropriate tension. A platen 124 and a platen roller 118 for maintaining appropriate flatness, a charging roller 116 for applying electrostatic charge for adsorbing the recording medium 114, a discharge roller 117 for holding the recording medium 114, and the recording medium 114 discharged A paper discharge mechanism including a paper discharge tray 104, a paper feed tray 103 for stocking the recording medium 114 to be printed, separation pads 112 and 122 for feeding the recording medium 114 one by one from the paper feed tray, the recording sent A counter to ensure that the medium 114 is attracted to the charging belt La 123 has a sheet feeding mechanism comprising a manual feed tray 105 to be used when the paper feed by manual feed.
Furthermore, the waste liquid tank 109 which collects the waste liquid discharged | emitted after maintenance, and the operation panel 106 which can operate an apparatus and can display an apparatus state are also provided.

  The nozzle array of each head unit is arranged to be orthogonal to the conveyance direction of the recording medium 114, and forms a nozzle array having a length longer than the recording area. The recording medium 114 is separated from the paper feed tray into one sheet by the separation roller, and is fixed on the conveyance belt by being closely attached to the conveyance belt by the pressure roller, and the liquid is transferred to the recording medium when passing under the head unit. By discharging the droplets, the recording medium can be patterned as droplets at high speed, separated from the conveyance belt by the separation claws, supported by the discharge roller and the discharge roller, and the recorded matter is discharged onto the discharge tray. Exhausted. The head unit of the aqueous ink and the head unit of the post-treatment liquid are adjacent to each other, and the post-treatment liquid is ejected onto the surface of the aqueous ink between 1 second and 3 seconds after the ejection of the aqueous ink.

  In addition, by heating the recording medium to which the post-processing liquid and the aqueous ink are attached by the hot air blower fan 150, it is possible to improve the abrasion resistance of the image by promoting the drying. Although the drying process is performed on the recording medium after recording using a hot air fan, the drying process may be performed on the recording medium before or after recording, and the method is not limited to the hot air fan. And means such as a heating roller and the like may be used in combination.

FIG. 3 is a schematic view showing an example of a head arrangement in a head unit of the image forming apparatus.
The head unit fixes the heads 154A to 154L to the head outer peripheral member 160, and the heads are alternately arranged such that a part of the nozzles overlap.
FIG. 4 is a schematic view showing the heads arranged in the head unit of FIG. 3. In each head, a nozzle 200 is provided with a nozzle 200, and a filler is provided between the head and the head outer peripheral member. Sealed at 202, the gap from the nozzle surface side is eliminated.

  Next, an outline of a control unit of the image forming apparatus shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a schematic block diagram of the control unit in FIG.

  The control unit 300 controls the entire apparatus, the CPU 301, a program executed by the CPU 301, the value of the nozzle surface contamination degree and the nozzle surface contamination tolerance threshold for predetermined ink ejection used in the present invention, drive waveform data, and other fixed data ROM 302 for storing image data, RAM 303 for temporarily storing image data, etc., non-volatile memory (NVRAM) 304 for holding data even while the power of the apparatus is shut off, various signal processing for image data, sorting And an ASIC 305 for processing input / output signals for controlling the entire apparatus and other image processing.

  The control unit 300 also includes a host I / F 306 for transmitting and receiving data and signals with the host side, and a head drive control unit 307 for generating a drive waveform for driving and controlling pressure generating means of the recording head 154. A recording medium conveyance motor drive control unit 308 for driving the recording medium conveyance motor 309, a maintenance unit movement motor drive control unit 312 for driving the head unit (carriage) movement motor 311, and an electromagnetic valve 315 for the ink path. Path control unit 314 for opening and closing control, liquid feed suction motor drive control unit 316 for controlling the drive of the cap suction motor 317 and the ink supply motor 318, detection according to the movement amount and movement speed of the transport belt 113 An encoder that outputs a signal, a sensor that detects environmental temperature and environmental humidity (whichever one of Detection signals from 323, the ink amount detection signal of the sub ink tank, and a like I / O322 for inputting detection signals from various sensors (not shown). The control unit 300 is connected to an operation panel 106 for inputting and displaying information necessary for the apparatus.

  The control unit 300 receives print data and the like from the host side of an information processing apparatus such as a personal computer, an image reading apparatus such as an image scanner, an imaging apparatus such as a digital camera, etc. .

  Then, the CPU 301 reads out and analyzes the print data in the reception buffer included in the host I / F 306, performs necessary image processing and data rearrangement in the ASIC 305, and arranges for one page of the head width of the recording head 154. The corresponding image data (dot pattern data) is sent to the head drive control unit 307 in synchronization with the clock signal. The dot pattern data for image output may be generated by storing font data in the ROM 302, for example, or the printer driver on the host side develops the image data into bitmap data and transfers it to this device You may do it.

  The head drive control unit 307 selectively applies the data to the pressure generation unit of the recording head 154 based on the image data (dot pattern data) corresponding to one page of the recording head 154 input in page units, and the recording head 154 Drive.

EXAMPLES The present invention will be described below by way of Examples and Comparative Examples, but the present invention is not limited to these Examples. In the table, the unit of the SP value is “(cal / cm ³ ) ^1/2 ”, and the unit of the amount of each component in the aqueous ink and the post-treatment liquid is “mass%”.

Example 1
<Water-based ink>
<< Preparation of anionic group-containing styrene-acrylic copolymer >>
550 g of methyl ethyl ketone is contained in a reaction container of an automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction container equipped with a stirring device, a dropping device, a temperature sensor and a reflux device having a nitrogen introducing device at the top The inside of the reaction vessel was purged with nitrogen while charging and stirring. After heating at 80 ° C. while maintaining the inside of the reaction vessel at a nitrogen atmosphere, 75.0 g of 2-hydroxyethyl methacrylate, 77.0 g of methacrylic acid, 80.0 g of styrene, and 150 of butyl methacrylate are added by a dropping device. A mixed solution of 0. 0 g, 98.0 g of butyl acrylate, 20.0 g of methyl methacrylate, and 40.0 g of "Perbutyl (registered trademark) O" (manufactured by NOF Corporation) was added dropwise over 4 hours. After completion of the dropwise addition, the reaction is further continued at the same temperature for 15 hours, acid value: 100 (measured according to the method described in JIS K 0070-1992), weight average molecular weight: 21,000 (D5280 LCS M-PDA, stock A methyl ethyl ketone solution of an anionic group-containing styrene-acrylic copolymer A at a glass transition temperature of 31 ° C. (measured by STA7200 manufactured by Hitachi High-Tech Science Co., Ltd.) was obtained. After completion of the reaction, a part of the methyl ethyl ketone was distilled off under reduced pressure to obtain an anionic group-containing styrene-acrylic copolymer A solution in which the nonvolatile content was adjusted to 50%.

<< Preparation of aqueous pigment dispersions >>
In a mixing tank equipped with a cooling jacket, 800 g of carbon black (trade name: Raven 1080, manufactured by Columbian Carbon Japan Ltd.) and 200 g of the solution of the above-mentioned styrene-acrylic copolymer A containing anionic group are hydroxylated by 10%. 143 g of sodium aqueous solution, 100 g of methyl ethyl ketone, and 1,957 g of water were charged and mixed with stirring. The mixed solution is passed through a dispersion device (trade name: SC Mill SC100, manufactured by Mitsui Mining Co., Ltd.) filled with zirconia beads of 0.3 mm in diameter, and a circulation method (a method of returning the dispersion liquid from the dispersion device to the mixing tank) Dispersed for 6 hours. The number of revolutions of the dispersing device was 2,700 revolutions / minute, and cold water was passed through the cooling jacket so that the dispersion temperature was kept at 40 ° C. or less. After completion of dispersion, the dispersion stock solution was drained from the mixing tank, and then the mixing tank and the dispersion device flow path were washed with 10,000 g of water and combined with the dispersion stock solution to obtain a diluted dispersion. The diluted dispersion was placed in a glass distillation apparatus, and the whole amount of methyl ethyl ketone and a part of water were distilled off. After cooling to room temperature, 10% hydrochloric acid was added dropwise while stirring to adjust to pH 4.5, and then the solid content was filtered and washed with a Nutsche-type filter device. Take the cake in a container, add 200 g of a 20% aqueous solution of potassium hydroxide, disperse it in Dispa (trade name: TK homodisper, manufactured by Primix Co., Ltd.), add water to prepare non-volatile matter, and then nonvolatile An aqueous pigment dispersion was obtained in which an amount of 20% of carbon black was dispersed in an aqueous medium as composite particles coated with a carboxyl group-containing styrene-acrylic copolymer neutralized in potassium hydroxide.

<< Preparation of water-based ink 1 >>
Rosin-modified maleic acid resin (carboxyl group-containing resin) 2.0 g, glycerin (water-soluble organic solvent, SP value: 16.38 (cal / cm ³ ) ^1/2 ) 20.0 g, 1,3-butanediol (water-soluble Organic solvent, SP value: 12.75 (cal / cm ³ ) ^1/2 ) 10.0 g, compound (fluorinated surfactant) represented by the formula (i) 0.4 g, 2-amino-2-ethyl 0.2 g of 1,3-propanediol (pH adjuster), 0.1 g of benzotriazole (antiseptic and rust inhibitor), and 58.1 g of water (SP value: 23.4 (cal / cm ³ ) ^1/2 ) The mixture was stirred for 1 hour and uniformly mixed. Next, 1.2 g of N-octyl-2-pyrrolidone (antifoam) was added, and the mixture was further stirred for 1 hour and uniformly mixed. Thereafter, 8.0 g of the aqueous pigment dispersion in terms of solid content was added, and the mixture was further stirred for 1 hour and uniformly mixed. This mixture was pressure-filtered with a polyvinylidene fluoride membrane filter having an average pore diameter of 0.8 μm to remove coarse particles and dust, to obtain an aqueous ink 1. The composition and content of the aqueous ink 1 are shown in Table 1.

  The volume average particle diameter (D50) of the coloring agent used in the present invention is 0.01% by mass of solid content concentration (mass concentration) in the measurement sample using Microtrac UPA-150 manufactured by Nikkiso Co., Ltd. It was 120 nm as a result of measuring using the sample diluted with pure water so that it might become.

<Post-treatment liquid>
-Preparation of post-treatment solution 1-
Water-soluble organic solvent A (glycerin, SP value: 16.38 (cal / cm ³ ) ^1/2 ) 2.5 g, water-soluble organic solvent B (3-methoxy-1-butanol, SP value: 9.98 (cal / Cm ³ ) ^1/2 ) 27.5 g, ether type urethane resin A (trade name: Permarine UA00, manufactured by Sanyo Chemical Industries, Ltd., volume average particle diameter (D50): 400 nm) 30.0 g, polyethylene type wax emulsion B (Brand name: Nopcoat PEM-17, manufactured by San Nopco Ltd., melting point: 105 ° C.) 5.0 g, isocyanate group-containing resin (trade name: Elastron E-37, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 2.0 g, 0.4 g of the compound represented by i), 2.0 g of N-octyl-2-pyrrolidone, 2.0 g of octanediol, 2-amino-2-ethyl-1,3-propa Diol 0.2 g, benzotriazole 0.1 g, and ion exchanged water (SP ^{value: 23.4 (cal / cm 3)} 1/2) used in 29.1g was stirred for 1 hour homogeneously mixed to Example 1 Post-treatment solution A was obtained.
The obtained aqueous ink 1 and post-treatment liquid A were used to make an image forming set.

(Examples 2 to 29 and Comparative Examples 1 to 4)
With regard to Examples 2 to 29 and Comparative Examples 1 to 4, similar to Example 1, except that the composition and content of the aqueous ink and the post-treatment liquid described in Table 2 to Table 8 were changed, an aqueous ink and It was a set for image formation of post-processing liquid. The composition and content of Examples 1 to 29 and Comparative Examples 1 to 4 are shown in Tables 2 to 8.

<Image formation method>
Recording medium (trade name: OK top coat +, manufactured by Oji Paper Co., Ltd.) using the aqueous ink used in Examples 1 to 29 and Comparative Examples 1 to 4 by an image forming apparatus (trade name: IPSIO GXe 5500, manufactured by Ricoh Co., Ltd.) To form a 3 cm square unfixed solid image formed in a dot pattern, and after 1.5 seconds, form the image as the post-processing liquid used in Examples 1 to 29 and Comparative Examples 1 to 4 as described above. The aqueous ink was discharged by the device onto the surface of the formed image. Thereafter, it was dried at 90 ° C. for 2 minutes with warm air and a drum heater to obtain a fixed image. In Example 29, the drying was not performed. The characteristics of the image were evaluated by the following method.

<< Glossiness of image >>
The image glossiness (60 ° gloss) of the solid portion of a 3 cm square solid image formed with a dot pattern was measured with a colorimeter (trade name: CR-400, manufactured by Konica Minolta Co., Ltd.). The higher the numerical value of the image glossiness, the better the glossiness of the image. If the image glossiness is 30% or more, it can be used without any practical problem.

<< Scratch resistance of image >>
Apply a cloth to a 3 cm square solid image solid part of the above image with a friction tester (trade name: Crockmeter, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and rub it, and transfer density of the ink to the cloth after rubbing It was measured by a spectrophotometric densitometer (trade name: X-Rite 939, manufactured by X-Rite). The smaller the transfer density, the better the scratch resistance of the image. If the transfer density is less than 0.20, it can be used practically without any problem.

<< Preservation stability >>
The post-treatment liquids used in Examples 1 to 29 and Comparative Examples 1 to 4 were left in a thermostat at 70 ° C. for 2 weeks, and the difference between the initial viscosity and the viscosity after storage (viscosity increase level) Based on the "preservation stability" was evaluated. In addition, when the following evaluation criteria are "(circle)", it can be used without a problem on practical use. The initial viscosity and the viscosity after storage were measured at 25 ° C. using a TV-22 viscometer (manufactured by Toki Sangyo Co., Ltd.).
-Evaluation criteria-
○: difference between initial viscosity and viscosity after storage is ± 5% or less Δ: difference between initial viscosity and viscosity after storage is more than ± 5% ± 10% ×: difference between initial viscosity and viscosity after storage Is more than ± 10%

<< Discharge stability >>
After printing a solid portion of a 3 cm square solid image of the above image, the recording head is left uncapped for 30 minutes, and then the same image is recorded again, and the number of non-ejection nozzles is measured. Based on the criteria, "discharge stability" was evaluated. In addition, when the following evaluation criteria are "(triangle | delta)" or more, it can be used practically without a problem.
-Evaluation criteria-
:: No discharge △: Less than 5 channels of non-discharge nozzles ×: More than 5 channels of non-discharge nozzles

＊水溶性有機溶剤Ｈは下記式（ＩＩ）で示される化合物（ＳＰ値：８．１０（ｃａｌ／ｃｍ^３）^１／２、商品名：ハイソルブ ＢＤＭ、東邦化学工業株式会社製）

＊水溶性有機溶剤Ｉは下記式（ＩＩＩ）で表される化合物（ＳＰ値：７．４０（ｃａｌ／ｃｍ^３）^１／２、商品名：ハイソルブ ＭＴＰＯＭ、東邦化学工業株式会社製）

＊エーテル型ウレタン樹脂Ａ：商品名：パーマリン ＵＡ００（三洋化成工業株式会社製、体積平均粒子径（Ｄ５０）：４００ｎｍ）
＊エーテル型ウレタン樹脂Ｂ：商品名：ＳＵ−１００Ｎ（中央理化工業株式会社製、体積平均粒子径（Ｄ５０）：８４ｎｍ）
＊エーテル型ウレタン樹脂Ｃ：商品名：Ｗ５６６１（三井化学株式会社製、体積平均粒子径（Ｄ５０）：１１ｎｍ）
＊エーテル型ウレタン樹脂Ｄ：商品名：ＸＷ−７５−Ｗ９３２（三井化学株式会社製、体積平均粒子径（Ｄ５０）：８ｎｍ）
＊アクリルシリコン系樹脂：商品名：ＡＱ９１４（ダイセルファインケム社製、体積平均粒子径（Ｄ５０）：１２０ｎｍ）
＊ポリエチレン型ワックスエマルジョンＡ：商品名：ノプコマル ＭＳ−４０（サンノプコ株式会社製、融点：７９℃）
＊ポリエチレン型ワックスエマルジョンＢ：商品名：ノプコート ＰＥＭ−１７（サンノプコ株式会社製、融点＝１０５℃）
＊ポリエチレン型ワックスエマルジョンＣ：商品名：ハイテック Ｅ−６３１４（東邦化学工業株式会社製、融点：１３７℃）
＊カルナバワックス：商品名：セロゾール ５２４（中京油脂株式会社製、融点：８３℃）
＊イソシアネート基含有樹脂：商品名：エラストロン Ｅ−３７、第一工業製薬株式会社製）
＊フッ素系界面活性剤である下記式（ｉ）で示される化合物（商品名：ユニダイン ＤＳＮ−４０３Ｎ）、ダイキン工業株式会社製）

In addition, "the SP value (I) of the urethane resin and / or acrylic resin in a post-treatment liquid" in Tables 2 to 8 is a case where two or more urethane resins are contained, or one or more urethane resins And an acrylic resin, the difference between the SP value (I) of the urethane resin and / or acrylic resin in the post-treatment liquid and the SP value (II) of the mixed solution in the post-treatment liquid is minimized The SP value of any one urethane resin or acrylic resin is shown.
Moreover, in Table 2-Table 8, about the symbol etc., the content as follows is shown.
* Water-soluble organic solvent A: Glycerin (SP value: 16.38 (cal / cm ³ ) ^1/2 , manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.)
* Water-soluble organic solvent B: 3-methoxy-1-butanol (SP value: 9.98 (cal / cm ³ ) ^1/2 , manufactured by Tokyo Chemical Industry Co., Ltd.)
* Water-soluble organic solvent C: 3-methoxy-3-methyl-1-butanol (SP value: 8.87 (cal / cm ³ ) ^1/2 , Tokyo Chemical Industry Co., Ltd.)
* Water-soluble organic solvent D: diethylene glycol monoisopropyl ether (SP value: 9.84 (cal / cm ³ ) ^1/2 , Tokyo Chemical Industry Co., Ltd.)
* Water soluble organic solvent E: diethylene glycol monoisobutyl ether (SP value: 9.44 (cal / cm ³ ) ^1/2 , Tokyo Chemical Industry Co., Ltd.)
* Water-soluble organic solvent F: tripropylene glycol methyl ether (SP value: 9.77 (cal / cm ³ ) ^1/2 , Tokyo Chemical Industry Co., Ltd.)
Water-soluble organic solvent G: a compound represented by the following formula (I) (SP value: 7.80 (cal / cm ³ ) ^1/2 , trade name: Hysorb MDPOM, manufactured by Toho Chemical Industry Co., Ltd.)

* Water-soluble organic solvent H is a compound represented by the following formula (II) (SP value: 8.10 (cal / cm ³ ) ^1/2 , trade name: Hysorb BDM, manufactured by Toho Chemical Industry Co., Ltd.)

* Water-soluble organic solvent I is a compound represented by the following formula (III) (SP value: 7.40 (cal / cm ³ ) ^1/2 , trade name: Hysorb MTPOM, manufactured by Toho Chemical Industry Co., Ltd.)

* Ether type urethane resin A: Brand name: Permarine UA00 (manufactured by Sanyo Chemical Industries, Ltd., volume average particle diameter (D50): 400 nm)
* Ether type urethane resin B: Brand name: SU-100N (manufactured by Chuo Rika Kogyo Co., Ltd., volume average particle diameter (D50): 84 nm)
* Ether-type urethane resin C: Product name: W5661 (Mitsui Chemical Co., Ltd., volume average particle diameter (D50): 11 nm)
* Ether type urethane resin D: Brand name: XW-75-W 932 (Mitsui Chemical Co., Ltd., volume average particle diameter (D50): 8 nm)
* Acrylic silicone resin: Brand name: AQ 914 (manufactured by Daicel Finechem, volume average particle diameter (D50): 120 nm)
* Polyethylene type wax emulsion A: Brand name: Nopko Mar MS-40 (manufactured by San Nopco Co., Ltd., melting point: 79 ° C.)
* Polyethylene type wax emulsion B: Brand name: Nop coat PEM-17 (manufactured by San Nopco Co., Ltd., melting point = 105 ° C)
* Polyethylene type wax emulsion C: Brand name: HITEC E-6314 (manufactured by Toho Chemical Industry Co., Ltd., melting point: 137 ° C.)
* Carnauba wax: Brand name: Cellosol 524 (manufactured by Chukyo Yushi Co., Ltd., melting point: 83 ° C.)
* Resin containing isocyanate group: Brand name: Elastron E-37, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
* A compound represented by the following formula (i) which is a fluorine-based surfactant (trade name: Unidyne DSN-403N), manufactured by Daikin Industries, Ltd.

＜５＞ 後処理液中のウレタン樹脂及びアクリル樹脂の少なくともいずれかの含有量が、後処理液全量に対して、１０質量％以上４０質量％以下であり、
前記ウレタン樹脂が、アニオン性自己乳化型のエーテル型ウレタン樹脂であり、
前記アクリル樹脂が、アクリルシリコーン型樹脂である前記＜１＞から＜４＞のいずれかに記載の画像形成用セットである。
＜６＞ 後処理液中のウレタン樹脂及びアクリル樹脂の少なくともいずれかが、体積平均粒子径が異なる少なくとも２種であり、
前記ウレタン樹脂及び前記アクリル樹脂の少なくともいずれか１種の体積平均粒子径が、水性インク中の着色剤の体積平均粒子径に対して、大きく、
前記ウレタン樹脂及び前記アクリル樹脂の少なくともいずれか他の１種の体積平均粒子径が、水性インク中の着色剤の体積平均粒子径に対して、小さい前記＜１＞から＜５＞のいずれかに記載の画像形成用セットである。
＜７＞ 後処理液が、ワックスをさらに含有し、
前記ワックスが、ポリエチレン型ワックスエマルジョン及びカルナバワックスの少なくともいずれかであり、かつ融点が、８０℃以上１４０℃以下であり、
前記ワックスの含有量が、後処理液全量に対して、１質量％以上１０質量％以下である前記＜１＞から＜６＞のいずれかに記載の画像形成用セットである。
＜８＞ 後処理液が、ウレタン樹脂及びアクリル樹脂の少なくともいずれかと架橋する自己架橋型樹脂をさらに含有し、
前記自己架橋型樹脂が、イソシアネート基含有樹脂であり、
前記自己架橋型樹脂の含有量が、後処理液全量に対して、１質量％以上１０質量％以下である前記＜１＞から＜７＞のいずれかに記載の画像形成用セットである。
＜９＞ 水性インクが、フッ素系界面活性剤をさらに含有する前記＜１＞から＜８＞のいずれかに記載の画像形成用セットである。
＜１０＞ 水性インク中の水溶性有機溶剤及び水の混合溶液における溶解パラメータが、１８（ｃａｌ／ｃｍ^３）^１／２以上２２（ｃａｌ／ｃｍ^３）^１／２以下である前記＜１＞から＜９＞のいずれかに記載の画像形成用セットである。
＜１１＞ 後処理液中の前記水溶性有機溶剤及び前記水の混合溶液における溶解パラメータが、１０（ｃａｌ／ｃｍ^３）^１／２以上３０（ｃａｌ／ｃｍ^３）^１／２以下である前記＜１＞から＜１０＞のいずれかに記載の画像形成用セットである。
＜１２＞ 後処理液中の水溶性有機溶剤及び水の混合溶液における溶解パラメータが、水性インク中の水溶性有機溶剤及び水の混合溶液における溶解パラメータに対して、３．０（ｃａｌ／ｃｍ^３）^１／２以上５．０（ｃａｌ／ｃｍ^３）^１／２以下低い前記＜１＞から＜１１＞にいずれかに記載の画像形成用セットである。
＜１３＞ 水性インク中の混合溶液における水溶性有機溶剤の含有量（質量％）と、水の含有量（質量％）との質量比（水溶性有機溶剤／水）が、０．５以上２以下である前記＜１＞から＜１２＞にいずれかに記載の画像形成用セットである。
＜１４＞ 後処理液中の混合溶液における水溶性有機溶剤の含有量（質量％）と、水の含有量（質量％）との質量比（水溶性有機溶剤／水）が、０．５以上２以下である前記＜１＞から＜１３＞にいずれかに記載の画像形成用セットである。
＜１５＞ ウレタン樹脂の最低造膜温度が、２５℃以下である前記＜１＞から＜１４＞にいずれかに記載の画像形成用セットである。
＜１６＞ フッ素系界面活性剤が、下記式（ｉ）で表される化合物である前記＜９＞から＜１５＞にいずれかに記載の画像形成用セットである。

＜１７＞ 前記＜１＞から＜１６＞のいずれかに記載の画像形成用セットを用いた画像形成装置であって、
記録媒体に水性インクを吐出して画像を形成する画像形成手段と、前記記録媒体の前記水性インクが吐出された面上に後処理液を付与する後処理手段とを有することを特徴とする画像形成装置である。
＜１８＞ 前記後処理手段後に、記録媒体を乾燥させる乾燥手段を有する前記＜１７＞に記載の画像形成装置である。
＜１９＞ 前記＜１＞から＜１６＞のいずれかに記載の画像形成用セットを用いた画像形成方法であって、
記録媒体に水性インクを吐出して画像を形成する画像形成工程と、前記記録媒体の前記水性インクが吐出された面上に後処理液を付与する後処理工程とを含むことを特徴とする画像形成方法である。
＜２０＞ 水性インクを吐出した１秒間後から３秒間後の間に後処理液を付与する前記＜１９＞に記載の画像形成方法である。 As an aspect of this invention, it is as follows, for example.
<1> A water-based ink containing a colorant, a water-soluble organic solvent, and water,
A post-treatment liquid containing at least one of a urethane resin and an acrylic resin, a water-soluble organic solvent, and water,
The solubility parameter of the mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is 1.5 (cal) to the solubility parameter of the mixed solution of the water-soluble organic solvent and the water in the aqueous ink. / Cm ³ ) ^1/2 or more lower, is an image forming set.
The solubility parameter in the mixed solution of the water-soluble organic solvent and water in the post-treatment liquid is 7.5 (cal / cm ^{3) with} respect to the solubility parameter in the mixed solution of the water-soluble organic solvent and water in the aqueous ink The image forming set according to <1>, wherein the image forming set is ^1⁄2 or less lower.
The difference between the solubility parameter of at least one of the urethane resin and the acrylic resin in the post-treatment liquid and the solubility parameter of the mixed solution of the water-soluble organic solvent and water in the post-treatment liquid is 4 (cal / cm ³⁾ It is a set for image formation as described in said <1> to <2> which is ^1/2 or less.
The water-soluble organic solvent in the post-treatment liquid is 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, diethylene glycol monoisopropyl ether, diethylene glycol monoisobutyl ether, tripropylene glycol methyl ether, 1-methoxy-2-propanol, a compound represented by the following formula (I), a compound represented by the following formula (II), and at least one selected from a compound represented by the following formula (III),
The image formation according to any one of <1> to <3>, wherein the content of the water-soluble organic solvent in the post-treatment liquid is 20% by mass or more and 40% by mass or less based on the total amount of the post-treatment liquid. It is a set.

<5> The content of at least one of the urethane resin and the acrylic resin in the post-treatment liquid is 10% by mass or more and 40% by mass or less based on the total amount of the post-treatment liquid,
The urethane resin is an anionic self-emulsifying ether-type urethane resin,
It is a set for image formation in any one of said <1> to <4> whose said acrylic resin is acrylic silicone type resin.
<6> At least one of the urethane resin and the acrylic resin in the post-treatment liquid is at least two different in volume average particle diameter,
The volume average particle diameter of at least one of the urethane resin and the acrylic resin is larger than the volume average particle diameter of the colorant in the aqueous ink,
In any one of the above <1> to <5>, the volume average particle diameter of at least one of the urethane resin and the acrylic resin is smaller than the volume average particle diameter of the colorant in the aqueous ink It is a set for image formation of description.
<7> The post-treatment liquid further contains wax,
The wax is at least one of a polyethylene type wax emulsion and a carnauba wax, and the melting point is 80 ° C. or more and 140 ° C. or less,
It is a set for image formation in any one of said <1> to <6> whose content of the said wax is 1 mass% or more and 10 mass% or less with respect to post-processing liquid whole quantity.
<8> The post-treatment liquid further contains a self-crosslinking resin crosslinked with at least one of a urethane resin and an acrylic resin,
The self-crosslinking resin is an isocyanate group-containing resin,
It is a set for image formation in any one of said <1> to <7> whose content of the said self-crosslinking type resin is 1 mass% or more and 10 mass% or less with respect to the post-processing liquid whole quantity.
<9> The image-forming set according to any one of <1> to <8>, wherein the aqueous ink further contains a fluorine-based surfactant.
The solubility parameter in the mixed solution of the water-soluble organic solvent in the <10> aqueous ink and water is 18 (cal / cm ³ ) ^1/2 or more and 22 (cal / cm ³ ) ^1/2 or less from the above <1> It is a set for image formation in any one of <9>.
<11> The dissolution parameter in the mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is 10 (cal / cm ³ ) ^1/2 or more and 30 (cal / cm ³ ) ^1/2 or less It is a set for image formation in any one of <1> to <10>.
The dissolution parameter in the mixed solution of the water-soluble organic solvent and water in the post-treatment liquid is 3.0 (cal / cm ³⁾ relative to the dissolution parameter in the mixed solution of the water-soluble organic solvent and water in the aqueous ink ^1/2 or more and 5.0 (cal / cm ³ ) ^1/2 or less The image forming set according to any one of <1> to <11>.
<13> The mass ratio (water-soluble organic solvent / water) of the content (mass%) of the water-soluble organic solvent in the mixed solution in the aqueous ink to the content (mass%) of water is 0.5 or more 2 It is a set for image formation in any one of said <1> to <12> which is the following.
<14> The mass ratio (water-soluble organic solvent / water) of the content (mass%) of the water-soluble organic solvent in the mixed solution in the post-treatment liquid to the content (mass%) of water is 0.5 or more It is a set for image formation in any one of said <1> to <13> which is 2 or less.
<15> The image forming set according to any one of <1> to <14>, wherein the minimum film forming temperature of the urethane resin is 25 ° C. or less.
<16> The image forming set according to any one of <9> to <15>, wherein the fluorine-containing surfactant is a compound represented by the following formula (i).

<17> An image forming apparatus using the image forming set according to any one of <1> to <16>,
An image forming unit configured to form an image by discharging an aqueous ink onto a recording medium; and a post-processing unit configured to apply a post-processing liquid onto the surface of the recording medium on which the aqueous ink is discharged. It is a forming device.
<18> The image forming apparatus according to <17>, further comprising a drying unit configured to dry the recording medium after the post-processing unit.
<19> An image forming method using the image forming set according to any one of <1> to <16>,
An image forming step of forming an image by discharging an aqueous ink onto a recording medium; and a post-processing step of applying a post-treatment liquid onto the surface of the recording medium on which the aqueous ink is discharged It is a formation method.
&Lt; 20 &gt; The image forming method according to &lt; 19 &gt;, wherein the post-treatment liquid is applied during 1 second to 3 seconds after the aqueous ink is ejected.

  The image forming set according to any one of <1> to <16>, the image forming apparatus according to any one of <17> to <18>, the image forming according to <19> to <20> The method is intended to solve the problems in the prior art and to achieve the following objects. That is, the image forming set, the image forming apparatus, and the image forming method aim to provide an image forming set, an image forming apparatus, and an image forming method in which the glossiness of an image can be obtained.

Patent No. 4525778 gazette Patent No. 5398401 gazette

Claims (11)

An aqueous ink containing a colorant, a water-soluble organic solvent, and water;
A post-treatment liquid containing at least one of a urethane resin and an acrylic resin, a water-soluble organic solvent, and water,
The solubility parameter of the mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is 1.5 (cal) with respect to the solubility parameter of the mixed solution of the water-soluble organic solvent and the water in the aqueous ink. / Cm ³ ) A set for forming an image characterized by being ^1/2 or more lower. The solubility parameter of the mixed solution of the water-soluble organic solvent and water in the post-treatment liquid is 7.5 (cal / cm ³ ) ^{1 /} to the solubility parameter of the mixed solution of the water-soluble organic solvent and water in the aqueous ink. The image forming set according to claim 1, wherein the set is ² or less lower. The difference between the solubility parameter of at least one of the urethane resin and the acrylic resin in the post-treatment liquid and the solubility parameter of the mixed solution of the water-soluble organic solvent and water in the post-treatment liquid is 4 (cal / cm ³ ) ^{1 /} The image forming set according to any one of claims 1 to 2, which is ² or less. The water-soluble organic solvent in the post-treatment solution is 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, diethylene glycol monoisopropyl ether, diethylene glycol monoisobutyl ether, tripropylene glycol methyl ether, 1-methoxy -2-propanol, a compound represented by the following formula (I), a compound represented by the following formula (II), and at least one selected from a compound represented by the following formula (III),
The image forming set according to any one of claims 1 to 3, wherein the content of the water-soluble organic solvent in the post-treatment liquid is 20% by mass or more and 40% by mass or less with respect to the total amount of the post-treatment liquid.

The content of at least one of the urethane resin and the acrylic resin in the post-treatment liquid is 10% by mass or more and 40% by mass or less with respect to the total amount of the post-treatment liquid,
The urethane resin is an anionic self-emulsifying ether-type urethane resin,
The image forming set according to any one of claims 1 to 4, wherein the acrylic resin is an acrylic silicone resin. At least one of the urethane resin and the acrylic resin in the post-treatment liquid is at least two different in volume average particle diameter,
The volume average particle diameter of at least one of the urethane resin and the acrylic resin is larger than the volume average particle diameter of the colorant in the aqueous ink,
The image according to any one of claims 1 to 5, wherein the volume average particle diameter of at least one of the urethane resin and the acrylic resin is smaller than the volume average particle diameter of the colorant in the aqueous ink. Set for formation. The post-treatment liquid further contains wax,
The wax is at least one of a polyethylene type wax emulsion and a carnauba wax, and the melting point is 80 ° C. or more and 140 ° C. or less,
The image forming set according to any one of claims 1 to 6, wherein the content of the wax is 1% by mass or more and 10% by mass or less with respect to the total amount of the post-treatment liquid. The post-treatment liquid further contains a self-crosslinking resin crosslinked with at least one of a urethane resin and an acrylic resin,
The self-crosslinking resin is an isocyanate group-containing resin,
The image forming set according to any one of claims 1 to 7, wherein the content of the self-crosslinking resin is 1% by mass or more and 10% by mass or less based on the total amount of the post-treatment liquid. An image forming apparatus using the image forming set according to any one of claims 1 to 8, wherein
An image forming unit configured to form an image by discharging an aqueous ink onto a recording medium; and a post-processing unit configured to apply a post-processing liquid onto the surface of the recording medium on which the aqueous ink is discharged. Forming device.   10. The image forming apparatus according to claim 9, further comprising drying means for drying the recording medium after the post-processing means. An image forming method using the image forming set according to any one of claims 1 to 8, wherein
An image forming step of forming an image by discharging an aqueous ink onto a recording medium; and a post-processing step of applying a post-treatment liquid onto the surface of the recording medium on which the aqueous ink is discharged Formation method.

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