JP2018090713A - Ink set and pretreatment ink used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set capable of obtaining excellent color reproducibility irrespective of the kind and the surface quality of recording media.SOLUTION: An ink set contains first white ink imparted to a recording medium, pretreatment ink which is formed of the first ink and is imparted onto the first ink, and second ink which is formed of the pretreatment ink and is imparted onto a pretreatment ink layer, where the first ink contains a first colorant, water and an organic solvent, the second ink contains a second colorant, water and an organic solvent, and the pretreatment ink contains an organic acid ammonium salt and a cationic resin.SELECTED DRAWING: None

Description

  The present invention relates to an ink set and a pretreatment ink used therefor.

  In ink jet printing using water-based ink, various recording media such as a recording medium having a coating layer, colored paper, a transparent recording medium, a recording medium having a non-smooth surface, and the like are used. In some cases, color reproducibility is difficult to obtain due to differences in background color or bleeding due to surface conditions. As a countermeasure, in a recording medium in which ink is difficult to permeate, a method of suppressing the bleeding by aggregating the ink with a pretreatment liquid with respect to bleeding generated by coalescence of ink droplets, or in a transparent recording medium, There is a method of printing with white background correction.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-152737) discloses a recording medium having a high white concealing property and a high-definition image in which bleeding of color ink is suppressed. Before recording a color image in a region where a color image is formed using a white ink composition for concealing to conceal the ground color and a white ink composition for suppressing bleeding to suppress blur of the color image. In addition, an image recording method for recording a white image by the white ink composition as an underlayer is disclosed. However, this technique has a problem that the color reproducibility is inferior due to the surface property of the recording medium.
Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-38063) discloses a recording medium with the object of providing an ink set containing white ink that can reproduce a colorful color image without being affected by the background color of the recording medium. A technique for controlling how white ink is applied in accordance with the background color is disclosed. However, this technique has a problem that color reproducibility is poor.
Patent Document 3 (Japanese Patent No. 5910372) discloses an ink pigment on a recording medium for the purpose of providing an image forming method that suppresses a decrease in the aggregation ability of an ink pigment and provides good image quality without bleeding. Discloses a technique for applying a pretreatment liquid for agglomerating particles. However, this technique has a problem that desired color reproducibility cannot be obtained depending on the color of the recording medium.
As described above, there is room for improvement in the color reproducibility in the prior art, and a technique for providing superior image quality is required.

  Accordingly, an object of the present invention is to provide an ink set that can obtain excellent color reproducibility regardless of the type and surface properties of the recording medium.

The above problem is solved by the following configuration 1).
1) A white first ink applied on a recording medium, a pretreatment ink applied on a first ink layer formed by the first ink, and a bottom formed by the pretreatment ink. An ink set containing a second ink applied on the treated ink layer,
The first ink contains a first color material, water and an organic solvent,
The second ink contains a second color material, water and an organic solvent,
The ink set according to claim 1, wherein the pretreatment ink contains an organic acid ammonium salt and a cationic resin.

  According to the present invention, there is provided an ink set capable of obtaining excellent color reproducibility irrespective of the type and surface properties of the recording medium.

Hereinafter, embodiments of the present invention will be described in more detail.
The ink set of the present invention has the following features in order to solve the above problems.
A white first ink applied on a recording medium, a pretreatment ink applied on a first ink layer formed by the first ink, and a pretreatment ink formed by the pretreatment ink A second ink applied on the layer,
The first ink contains a first coloring material, water, and an organic solvent,
The second ink contains a second color material, water, and an organic solvent,
The pretreatment ink contains an organic acid ammonium salt and a cationic resin.

  According to the above configuration, the whiteness of the recording medium is corrected by the white first ink, and the prevention of bleeding and the improvement of the glossiness are achieved by the pretreatment ink. Therefore, a printed matter with high color reproducibility can be provided regardless of the color and transparency of the recording medium.

Here, the first white ink in the present invention is
Printer: Ricoh Co., Ltd. IPSiO GXe5500
Printing medium: Lufina Color Black 128gsm manufactured by Oji F-Tex
Print resolution: 1200 dpi x 1200 dpi
Amount of ink adhesion: An ink having a Hunter whiteness calculated by the following formula (1) of 70 or more for a recorded matter printed under the condition of ² mg / cm ² or more.
Hunter whiteness = 100 − [(100−L ^* ) ² + (a ^{* 2} + b ^{* 2} )] ^0.5 (1)
Hunter whiteness is defined in JIS P8123, and L ^* , a ^* , and b ^* are color display methods defined by the International Commission on Illumination (CIE).

<White first ink>
The first white ink contains the first coloring material. Various pigments can be used as the first coloring material, but titanium oxide is desirable from the viewpoint of high whiteness. Further, the volume average particle size (hereinafter “particle size”) of titanium oxide is preferably 100 nm or more and 400 nm or less, and more preferably 100 nm or more and 300 nm or less. The particle size of the pigment particles can be measured using a dynamic light scattering (DLS) particle size distribution measuring device: Nanotrac Wave-EX150 (manufactured by Microtrac Bell Co., Ltd.). Examples of white color materials other than titanium oxide include hollow resin particles, other metal oxides, alkaline earth metal sulfates, carbonates, and the like.
The content of the first color material is, for example, 5 to 20% by mass in the first ink, and preferably 5 to 10% by mass.

  By applying the first white ink on the recording medium, a first ink layer having a Hunter whiteness of 70 or more is formed, thereby sufficiently concealing the color and transparency of the recording medium. . Furthermore, when used in combination with the pretreatment ink described below, a color gamut comparable to a recording medium having a Hunter whiteness of 70 or more can be obtained even if the Hunter whiteness is poor or the recording medium is light transmissive. The smoothness of the surface is improved, and as a result, the color reproducibility is improved.

The first white ink generally further contains an organic solvent and water, and may contain other known additives as necessary.
As other additives such as an organic solvent and a surfactant, the same materials as those used for the second ink described below can be used.

<Pretreatment ink>
The pretreatment ink in the present invention is an ink applied on the first ink layer. The pretreatment ink contains an organic acid ammonium salt and a cationic resin. Due to the film-forming property of the water-soluble cationic resin, the smoothness of the printing surface is improved, and as a result, the color reproducibility is improved. Further, since the organic acid ammonium salt acts as a flocculant and can aggregate the color material to prevent bleeding, the color reproducibility can be further improved. Further, since the resin particles are cationic, aggregation of the coloring material is promoted and the resin particles are prevented from aggregating in the pretreatment ink.

The pretreatment ink preferably does not contain a color material. If the pretreatment ink contains a color material, the color material may aggregate in the pretreatment ink due to the action of a cationic resin or an organic acid ammonium salt.
On the other hand, in the case of using a recording medium with low whiteness, a light-transmitting recording medium, or a recording medium with low smoothness, in order to obtain a uniform surface with Hunter whiteness of 70 or more, generally the first white ink There is a method of increasing the coating amount of a white pigment or using a white pigment having a large particle diameter. However, with such a method, the smoothness of the printing surface is likely to deteriorate, and the color reproducibility deteriorates. In the present invention, such a problem can be solved by using the pretreated ink.

Although a well-known thing can be used as a cationic resin, The cationic resin which consists of an amine or an amide derivative and an epihalohydrin is preferable.
Specifically, a cationic resin selected from a polyamine-epihalohydrin copolymer, a polyamide-epihalohydrin copolymer, a polyamide polyamine-epihalohydrin copolymer, and an amine-epihalohydrin copolymer is preferable.

Particularly preferred cationic resins are the following (A), (B) and (C).
(A) Copolymer represented by the following general formula (2)

  In the above formula, R1 to R8 may be the same or different and each represents an alkyl group having 1 to 8 carbon atoms, a hydroxyalkyl group, an alkenyl group, or a benzyl group, and X is a halogen atom ( For example, F, Cl, Br, I) are shown, and n is 1 or 2.

(B) A copolymer having a repeating unit represented by the following general formula (3)

  In the above formula, X represents a halogen atom (for example, F, Cl, Br, I), and m represents an integer of 1 or more. Further, both ends of the copolymer may be a monomer constituting a repeating unit or a known initiator.

(C) A copolymer of an amine monomer (diethylenetriamine) represented by the following general formula (4), a monomer represented by the following general formula (5), and a monomer represented by the following general formula (6)

  In the above formula, X represents a halogen atom (for example, F, Cl, Br, I).

As the amine monomer, triethylenetetraamine, tetraethylenepentamine, iminobispropylamine, and the like can be used in addition to the diethylenetriamine represented by the general formula (4).
Examples of other cationic resins include poly (vinyl pyridine) salts, polyalkylaminoethyl acrylate, polyalkylaminoethyl methacrylate, poly (vinyl imidazole), polyethyleneimine, polybiguanide, polyguanide, polyamine and derivatives thereof, or Examples include polyallylamine and derivatives thereof.
Furthermore, a quaternary ammonium salt type cationic resin or, in some cases, a water-dispersible cationic resin may be used.

  Commercially available cationic resins include Unisense KHE100L (manufactured by Senka), PDT-2 (manufactured by Yokkaichi Gosei), SC-506 (manufactured by Hymo), DK6810 (manufactured by Seiko PMC), and Pool Skit (Shimada Shoten) Manufactured).

  The weight average molecular weight of the cationic resin varies depending on the type of copolymer, and in the case of a polyamine-epihalohydrin copolymer, 500 to 100,000 is preferable, and in the case of a polyamide-epihalohydrin copolymer or a polyamide polyamine-epihalohydrin copolymer, The range of 5 million or less is preferable, and in the case of an amine-epihalohydrin copolymer, 700 to 50,000 is preferable. The cationic resin may be used after being granulated.

Among these, from the viewpoint of improving the effect of the present invention, the cationic resin is preferably a polyamine-epichlorohydrin copolymer having a structural unit derived from polyamine and a structural unit derived from epichlorohydrin. The cationic degree of the polyamine-epichlorohydrin copolymer is preferably 3 [meq / g] or more, preferably 3 [meq / g] or more and 8 [meq] in order to prevent aggregation due to the coexisting organic acid ammonium salt. / G] or less is more preferable.
The cation degree can be determined by colloid titration using a polyvinyl potassium sulfate reagent. The detailed procedure is as follows.
Take 90 mL of deionized water in a conical beaker, add 10 mL of a 500 ppm aqueous solution of the sample (in terms of dry product) to pH 4.0 with an aqueous hydrochloric acid solution, and stir for about 1 minute. Then add 2-3 drops of toluidine blue indicator and titrate with N / 400 potassium potassium sulfate reagent (N / 400 PVSK). The titration rate is 2 mL / min, and the end point is the time when the sample water changes from blue to magenta and is held for 10 seconds or more. The formula for calculating the degree of cation [meq / g] is as follows.
Cation degree = (N / 400 PVSK titration) × (N / 400 PVSK titer) / 2

  As the organic acid ammonium salt, for example, ammonium lactate salt, ammonium citrate salt, ammonium malate salt and the like are preferable, and ammonium lactate is particularly preferable in consideration of the cohesiveness of the coloring material and the corrosiveness to the metal member.

It is desirable that the content of the cationic resin in the pretreatment ink is larger than that of the organic acid ammonium salt from the viewpoint of improving the glossiness.
Specifically, the content of the cationic resin is preferably 30 to 60% by mass, and more preferably 40 to 60% by mass with respect to the total amount of the pretreated ink. When the content of the cationic resin fine particles is 30% by mass or more, smoothness is further improved and excellent color reproducibility can be provided. Further, when it is 60% by mass or less, there is no problem in blending other additives that impart, for example, permeability and wettability. 10-20 mass% is preferable and, as for content of organic acid ammonium salt, 12-18 mass% is more preferable. When the content of the organic acid ammonium salt is 10% by mass or more, the aggregation effect of the coloring material is increased, and the image quality can be improved. Moreover, when it is 20 mass% or less, it will not interfere with the mixing | blending of another additive.

The pretreatment ink contains the organic acid ammonium salt and the cationic resin as the essential components. Further, the pretreatment ink generally further contains an organic solvent and water, and may contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic / antifungal agent, an antirust agent, and the like as necessary.
The organic solvent, surfactant, antifoaming agent, pH adjuster, antiseptic / antifungal agent, and rust preventive agent can be the same materials as those used for the second ink described below, and others are known. Additives can be appropriately selected and used.

  Next, the second ink used in the present invention will be described. The second ink is an ink that contains a second color material, water, and an organic solvent, and is applied onto the pretreatment ink layer formed by the pretreatment ink. The second color material may be the same as or different from the first color material. In the following description, the second ink and the second color material may be simply referred to as ink and color material, respectively.

<Ink>
Hereinafter, the organic solvent, water, color material, resin, additive, and the like used for the ink will be described.

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include, for example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, Glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-he Polyhydric alcohols such as sundiol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, petriol, ethylene glycol mono Polyhydric alcohol alkyl ethers such as ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monophenyl ether, ethylene glycol mono Polyhydric alcohol aryl ethers such as benzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl- -N-containing heterocyclic compounds such as pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone, formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, Amides such as N-dimethylpropionamide and 3-butoxy-N, N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol, propylene carbonate, Examples thereof include ethylene carbonate.
In addition to functioning as a wetting agent, it is preferable to use an organic solvent having a boiling point of 250 ° C. or lower because good drying properties can be obtained.

A polyol compound having 8 or more carbon atoms and a glycol ether compound are also preferably used. Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, and the like.
Specific examples of glycol ether compounds include polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Examples of ethers include polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

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

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

<Water>
The water content in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 90% by mass or less, and 20% by mass from the viewpoint of ink drying property and ejection reliability. % To 60% by mass is more preferable.

<Color material>
The color material is not particularly limited, and pigments and dyes can be used.
An inorganic pigment or an organic pigment can be used as the pigment. These may be used alone or in combination of two or more. A mixed crystal may be used.
As the pigment, for example, a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, a white pigment, a green pigment, an orange pigment, a glossy pigment such as gold or silver, a metallic pigment, or the like can be used.
Carbon black produced by known methods such as contact method, furnace method, thermal method in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow as inorganic pigments Can be used.
Organic pigments include azo pigments, polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments). Dye chelates (for example, basic dye type chelates, acidic dye type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used. Of these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments include black for carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (CI pigment black 11). And metal pigments such as titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1).
Further, for color use, C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3, 15: 4 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.
The dye is not particularly limited, and an acid dye, a direct dye, a reactive dye, and a basic dye can be used. One kind may be used alone, or two or more kinds may be used in combination.
Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive black 3, 4, and 35 are mentioned.

  The content of the color material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass from the viewpoints of improvement in image density, good fixability and ejection stability. It is as follows.

<Resin>
The type of resin contained in the ink is not particularly limited and can be appropriately selected according to the purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene type Examples thereof include resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, and acrylic silicone resins.
Resin particles made of these resins may be used. An ink can be obtained by mixing resin particles with a material such as a colorant or an organic solvent in a resin emulsion state in which water is dispersed as a dispersion medium. As said resin particle, what was synthesize | combined suitably may be used and a commercial item may be used. Moreover, these may be used individually by 1 type, or may be used in combination of 2 or more types of resin particles.

The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 nm or more and 1,000 nm or less from the viewpoint of obtaining good fixability and high image hardness. It is more preferably 200 nm or less and particularly preferably 10 nm or more and 100 nm or less.
The volume average particle diameter can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

  The resin content is not particularly limited and may be appropriately selected according to the purpose. However, from the viewpoint of fixability and ink storage stability, the content of the resin is 1% by mass or more and 30% by mass or less. Is preferable, and 5 mass% or more and 20 mass% or less are more preferable.

<Additives>
If necessary, a surfactant, an antifoaming agent, an antiseptic / antifungal agent, a rust inhibitor, a pH adjuster, and the like may be added to the ink.

<Surfactant>
As the surfactant, any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants and anionic surfactants can be used.
There is no restriction | limiting in particular in silicone type surfactant, According to the objective, it can select suitably. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, and side chain both terminal modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferred because they exhibit good properties as an aqueous surfactant. In addition, as the silicone surfactant, a polyether-modified silicone surfactant can be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the side chain of the Si portion of dimethylsiloxane.
Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. Polyoxyalkylene ether polymer compounds are particularly preferred because of their low foaming properties. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylate. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain include a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers. As counter ions of salts in these fluorosurfactants, 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. are mentioned.
Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Nonionic surfactants include, for example, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan Examples include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.
These may be used alone or in combination of two or more.

The silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, side Since both ends of the chain are modified with polydimethylsiloxane, a polyether-modified silicone surfactant having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group exhibits good properties as an aqueous surfactant. preferable.
As such a surfactant, an appropriately synthesized product or a commercially available product may be used. Commercially available products can be obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.
The polyether-modified silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a polyalkylene oxide structure represented by the general formula (S-1) is represented by dimethylpolysiloxane. Examples thereof include those introduced into the side chain of Si part of siloxane.

一般式（Ｓ−１）

Formula (S-1)

(In the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R ′ represents an alkyl group.)
A commercial item can be used as said polyether modified silicone type surfactant, For example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS- 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Bic Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), etc. are mentioned.

As the fluorine-based surfactant, a fluorine-substituted compound having 2 to 16 carbon atoms is preferable, and a fluorine-substituted compound having 4 to 16 carbon atoms is more preferable.
Examples of the fluorosurfactant include perfluoroalkyl phosphate compounds, perfluoroalkylethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain. Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferred because of their low foaming properties, and are particularly fluorine-based compounds represented by the general formulas (F-1) and (F-2). A surfactant is preferred.

一般式（Ｆ−１）

Formula (F-1)

In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10 and n is preferably an integer of 0 to 40 in order to impart water solubility.
General formula (F-2)
_{C n F 2n + 1- CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y
In the compound represented by the general formula (F-2), Y is H, or CmF _{2m + 1} , m is an integer of 1 to 6, or CH ₂ CH (OH) CH ₂ —CmF _{2m + 1,} where m is 4 to 6. An integer, or CpH _{2p + 1} , p is an integer of 1-19. n is an integer of 1-6. a is an integer of 4-14.
A commercial item may be used as said fluorosurfactant. As this commercial item, for example, Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F -1405, F-474 (all manufactured by Dainippon Ink & Chemicals, Inc.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours); FT-110, FT-250 FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (Omnova) Manufactured), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) and the like. Among these, good print quality, particularly color developability, penetrability to paper, wettability, and leveling are significantly improved. FS-3100, FS-34, FS-300 manufactured by Chemours, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd. Particularly preferred are Fox PF-151N and Unidyne DSN-403N manufactured by Daikin Industries, Ltd.

  There is no restriction | limiting in particular as content of surfactant in an ink, Although it can select suitably according to the objective, From the point which is excellent in wettability and discharge stability, and image quality improves, it is 0.001 mass. % To 5% by mass is preferable, and 0.05% to 5% by mass is more preferable.

<Antifoaming agent>
There is no restriction | limiting in particular as an antifoamer, For example, a silicone type antifoamer, a polyether type | system | group antifoamer, a fatty-acid ester type | system | group antifoamer etc. are mentioned. These may be used alone or in combination of two or more. Among these, a silicone type antifoaming agent is preferable from the viewpoint of excellent foam breaking effect.

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

<Rust preventive>
There is no restriction | limiting in particular as a rust preventive agent, For example, acidic sulfite, sodium thiosulfate, etc. are mentioned.

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

There is no restriction | limiting in particular as a physical property of an ink, According to the objective, it can select suitably, For example, it is preferable that a viscosity, surface tension, pH, etc. are the following ranges.
The viscosity at 25 ° C. of the ink is preferably 5 mPa · s or more and 30 mPa · s or less, preferably 5 mPa · s or more and 25 mPa · s or less from the viewpoint of improving the printing density and character quality and obtaining good discharge properties. More preferred. Here, for the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. Measurement conditions are 25 ° C., standard cone rotor (1 ° 34 ′ × R24), sample liquid amount 1.2 mL, rotation speed 50 rpm, and measurement is possible for 3 minutes.
The surface tension of the ink is preferably 35 mN / m or less and more preferably 32 mN / m or less at 25 ° C. from the viewpoint that the ink is suitably leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12 and more preferably 8 to 11 from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

<Post-treatment liquid>
The post-treatment liquid is not particularly limited as long as a transparent layer can be formed. The post-treatment liquid is obtained by selecting and mixing an organic solvent, water, resin, surfactant, antifoaming agent, pH adjuster, antiseptic / antifungal agent, rust inhibitor, and the like as necessary. Further, the post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

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

<Recorded material>
The ink recorded matter of the present invention has an image formed using the ink of the present invention on a recording medium.
Recording can be performed by recording with an inkjet recording apparatus and an inkjet recording method.

  The method of using the ink is not limited to the ink jet recording method, and can be widely used. Besides the ink jet recording method, for example, a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method, a spray coating method and the like can be mentioned.

  Further, the terms “image formation”, “recording”, “printing”, “printing”, etc. in the terms of the present invention are all synonymous.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Examples 1-14
<Preparation of white first ink and pretreatment ink>
A white first ink was prepared using the materials and blending ratios shown in Table 1 below.
Further, a pretreated ink was prepared according to the materials and blending ratios shown in Table 2 below.
Each material was sufficiently stirred with a stirrer and mixed uniformly to prepare each ink.
Details of the ink material are as follows.

・ NeoCryl A-1127 (acrylic resin emulsion) manufactured by Enomoto Kasei Co., Ltd.
・ U-coat UWS-145 (polyurethane resin emulsion) manufactured by Sanyo Chemical Industries
・ Titanium oxide manufactured by Dainichi Seika Kogyo Co., Ltd. ・ DK6810 manufactured by Seiko PMC Co., Ltd. (polyamine-epichlorohydrin copolymer, cation degree is 5.7 [meq / g])
・ Lion Specialty Chemicals Leo Guard KGP (cationized hydroxypropylhydroxyethylcellulose)
・ Ammonium lactate salt made by Musashino Chemical Laboratory Co., Ltd. ・ Ammonium citrate salt (prepared by adding ammonia water to citric acid to neutralize)
・ Emulgen LS-106 (polyoxyalkylene alkyl ether) manufactured by Kao Corporation

<Printing>
The white first ink prepared as described above was filled in an ink cartridge dedicated to an inkjet printer (IPSiO GXe5500, manufactured by Ricoh) and set in the printer. Printing was carried out at a pixel density of 1200 dpi on a lumina color black 127 gsm manufactured by Oji F-Tex Co., Ltd. with an adhesion amount adjusted to a Hunter whiteness of 70 and dried at 90 ° C. in a thermostatic bath. Next, on the first ink layer formed by the first ink, the pretreatment ink was applied by roller application so as to be ² g / m ^2, and again dried in a thermostatic bath at 90 ° C. Finally, with an ink jet printer (IPSiO GXe5500 manufactured by Ricoh), a color image is formed on the pretreated ink layer formed by the pretreated ink using an ink containing a colorant, water, and an organic solvent attached to GXe5500. Printed.

Example 15
In Example 1, Example 1 was repeated except that the recording medium was changed to MIMAKI ENGINEERING CO., LTD.

Comparative Example 1
In Example 1, Example 1 was repeated except that the white first ink was not used.

Comparative Example 2
In Example 1, Example 1 was repeated except that no pretreatment ink was used.

  The following evaluation was performed about the color image obtained in Examples 1-15 and Comparative Examples 1-2. The results are shown in Table 3.

<Image evaluation (color reproducibility)>
[Color reproducibility evaluation criteria] (◎ and ○ are acceptable)
The area of the a * -b * hue diagram was determined and evaluated according to the following criteria when Comparative Example 2 was taken as 100%.
A: Area ratio is 110% or more of the comparative example B: Area ratio exceeds 100% and less than 110% X: Area ratio is 100% or less

<Image evaluation (beading)>
[Whiteness evaluation criteria] (◎ and ○ are acceptable)
◎: No beading is observed ○: Slight beading is observed ×: Beading is observed

<Image evaluation (smoothness)>
The white first ink and the pretreatment ink were applied on the recording medium, and the smoothness (surface roughness) of the recording medium after drying was evaluated according to the following criteria.
[Surface roughness evaluation criteria] (◎ and ○ are acceptable)
A: The surface roughness is significantly improved from the original recording medium. O: The surface roughness is improved from the original recording medium. X: The surface roughness is equal to or less than the original recording medium.

<Corrosive>
For metal corrosiveness, a piece of stainless steel (standard name: SUS303) is immersed in the pretreated inks g to o, and left for 2 weeks in a room temperature environment (evaluation environment: temperature 23 ± 1 ° C., humidity 50 ± 10%). Visual evaluation was performed according to the following criteria.
[Corrosion Evaluation Criteria] (◎ and ○ are acceptable)
◎: No corrosion ○: Slight decrease in metallic luster ×: Corrosion

The recording media are as follows.
p: Lufina Color Black 127gsm manufactured by Oji F-Tex Co., Ltd.
q: MIMAKI ENGINEERING CO., LTD.

From the results in Table 3, when the ink set of the example of the present invention was used, excellent color reproducibility was obtained, and beading, surface roughness, and corrosivity were also evaluated well.
On the other hand, since the comparative example 1 did not use the white first ink, the color reproducibility deteriorated.
In Comparative Example 2, since no pretreatment ink was used, color reproducibility, beading, and surface roughness were deteriorated.

JP 2011-152737 A JP 2002-38063 A Japanese Patent No. 5910372

Claims (9)

A white first ink applied on a recording medium, a pretreatment ink applied on a first ink layer formed by the first ink, and a pretreatment ink formed by the pretreatment ink A second ink applied on the layer, the ink set comprising:
The first ink contains a first color material, water and an organic solvent,
The second ink contains a second color material, water and an organic solvent,
The ink set according to claim 1, wherein the pretreatment ink contains an organic acid ammonium salt and a cationic resin.   The ink set according to claim 1, wherein the pretreatment ink does not include a color material.   The ink set according to claim 1 or 2, wherein the cationic resin includes a copolymer having a structural unit derived from polyamine and a structural unit derived from epichlorohydrin.   The ink set according to claim 1, wherein the organic acid ammonium salt is an ammonium lactate salt.   The ink set according to claim 1, wherein the first color material is titanium oxide.   The ink set according to claim 1, wherein the first color material has a volume average particle diameter of 100 nm or more and 400 nm or less.   The ink set according to claim 1, wherein the cationic resin has a cation degree of 3 [meq / g] or more.   8. The recording medium according to claim 1, wherein the area to which the first ink is applied has a whiteness of less than 70, or is a light-transmitting recording medium. Ink set. A white first ink applied on a recording medium, a pretreatment ink applied on a first ink layer formed by the first ink, and a pretreatment ink formed by the pretreatment ink A second ink applied on the layer, and used in an ink set containing the pretreatment ink,
The pretreatment ink contains an organic acid ammonium salt and a cationic resin,
The first ink contains a first color material, water and an organic solvent, and the second ink contains a second color material, water and an organic solvent.
A pretreatment ink characterized by the above.