JP2006083303A - Ink set for inkjet, inkjet recording apparatus and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set for inkjet excellent in rubbing resistance and to provide an inkjet recording apparatus and an inkjet recording method. <P>SOLUTION: The ink set for inkjet comprises a first liquid containing at least coloring material, a polymer substance, a water-soluble solvent and water and a second liquid containing at least a flocculating agent, a water-soluble solvent and water and further contains a plasticizer in at least either one of the first liquid and the second liquid. The inkjet recording apparatus and the inkjet recording method are each obtained by using the ink set. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet ink set, an ink jet recording apparatus, and an ink jet recording method.

  A so-called ink jet system that discharges ink such as liquid or molten solid from an ink discharge port such as a nozzle, slit, or porous film is used in many printers because of its small size and low cost. . Among these inkjet methods, the piezo inkjet method that discharges ink by using deformation of piezoelectric elements, or the thermal inkjet method that uses the boiling phenomenon of ink by thermal energy, etc. is widely used from the viewpoint of high resolution and high-speed printability. Has been. Further, the ink jet printer can print not only on so-called paper such as plain paper and ink jet exclusive paper but also on a film such as an OHP sheet or cloth.

Ink-jet recording inks using pigments as colorants are known (see, for example, Patent Documents 1 to 3). An ink using a pigment as a coloring material is advantageous in high image quality, water resistance, and light resistance because the pigment is more easily held on the surface of the paper than a dye. However, the abrasion resistance is inferior, and the fixing reliability of the image may be lowered.
JP-A-9-207424 Japanese Patent Laid-Open No. 9-234944 JP 2003-2131181 A

  The present invention has been made to solve the above conventional problems, and an object thereof is to provide an ink jet ink set, an ink jet recording apparatus, and an ink jet recording method which are excellent in abrasion resistance.

That is, the present invention
<1> A second liquid containing at least a coloring material, a polymer substance, a water-soluble solvent, and water, at least a flocculant, a water-soluble solvent, and water. The inkjet ink set further includes a plasticizer in at least one of the first liquid and the second liquid.

  <2> The inkjet ink set according to <1>, wherein the difference between the SP value of the plasticizer and the SP value of the polymer substance is 2.0 or less.

  <3> The mass mixing ratio of the polymer substance and the plasticizer in the 1: 1 liquid mixture of the first liquid and the second liquid is 1: 0.005 to 1: 0.4. The ink set for inkjet according to <1>.

  <4> The inkjet ink set according to <1>, wherein the content of the polymer substance in the first liquid is 20 to 150% by mass with respect to the content of the coloring material.

  <5> The inkjet ink set according to claim 1, further comprising a third liquid having a pH of 8 or more.

  <6> An inkjet recording apparatus including a recording head for ejecting each liquid in an inkjet ink set, wherein the inkjet ink set includes at least a colorant, a polymer substance, a water-soluble solvent, and water. And a second liquid containing at least a flocculant, a water-soluble solvent, and water, and at least one of the first liquid and the second liquid. The ink jet recording apparatus further includes a plasticizer.

  <7> The inkjet recording apparatus according to <6>, wherein a difference between an SP value of the plasticizer and an SP value of the polymer substance is 2.0 or less.

  <8> The mass mixing ratio of the polymer substance and the plasticizer in the 1: 1 liquid mixture of the first liquid and the second liquid is 1: 0.005 to 1: 0.4. <6> The inkjet recording apparatus according to

  <9> The inkjet recording apparatus according to <6>, wherein the content of the polymer substance in the first liquid is 20 to 150% by mass with respect to the content of the coloring material.

  <10> The inkjet recording apparatus according to <6>, wherein the inkjet ink set further includes a third liquid having a pH of 8 or more.

  <11> A second liquid containing at least a coloring material, a polymer substance, a water-soluble solvent, and water, and at least a flocculant, a water-soluble solvent, and water. And an ink jet ink set that further contains a plasticizer in at least one of the first liquid and the second liquid, and the first liquid and the second liquid are This is an ink jet recording method in which an image is formed by being applied on a recording medium so as to come into contact.

  <12> The inkjet recording method according to <11>, wherein a difference between an SP value of the plasticizer and an SP value of the polymer substance is 2.0 or less.

  <13> The mass mixing ratio of the polymer substance and the plasticizer in the 1: 1 liquid mixture of the first liquid and the second liquid is 1: 0.005 to 1: 0.4. The inkjet recording method according to <11>.

  <14> The inkjet recording method according to <11>, wherein the content of the polymer substance in the first liquid is 20 to 150% by mass with respect to the content of the coloring material.

  <15> The inkjet ink set further includes a third liquid having a pH of 8 or more, and the first liquid, the second liquid, and the third liquid are in contact with each other. The inkjet recording method according to <11>, wherein the image is formed on the recording medium.

  ADVANTAGE OF THE INVENTION According to this invention, the ink set for inkjets excellent in abrasion resistance, an inkjet recording device, and the inkjet recording method can be provided.

The ink jet ink set, ink jet recording apparatus and ink jet recording method of the present invention will be described in detail below.
<Inkjet ink set>
The inkjet ink set of the present invention includes at least a colorant, a polymer substance, a water-soluble solvent, water, a first liquid containing water, at least a flocculant, a water-soluble solvent, and water. A second liquid to be contained, and at least one of the first liquid and the second liquid further contains a plasticizer.
By mixing the two types of liquid according to the ink jet ink set of the present invention, a pigment aggregate containing a color material, a polymer substance, and a plasticizer is formed. Since the pigment aggregate containing a plasticizer is excellent in plasticity, the film formability on the substrate is improved. As a result, the ink set for inkjet according to the present invention can form an image having excellent abrasion resistance.
Hereinafter, the materials contained in each liquid constituting the ink set for inkjet according to the present invention will be sequentially described.

―Color material―
In the inkjet ink set of the present invention, any of organic pigments and inorganic pigments can be used as a color material. Examples of black pigments include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. In addition to black, cyan, magenta, and yellow primary pigments, specific color pigments such as red, green, blue, brown, and white, metallic luster pigments such as gold and silver, colorless or light color extender pigments, plastic pigments, etc. May be used. In addition, a newly synthesized pigment may be used for the present invention.
Furthermore, in the present invention, silica, alumina, polymer beads, or the like as a core, and a dye or pigment fixed on the surface thereof, a dye insoluble lake, a colored emulsion, a colored latex, or the like may be used as a pigment. Is possible.

  Specific examples of black pigments include Raven7000, Raven5750, Raven5250, Raven5000 ULTRAII, Raven3500, Raven2000, Raven1500, Raven1250, Raven1200, Raven1125, Raven10, Raven10, Raven10 Regal 330R, Regal 660R, Mogul L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 140 0 (manufactured by Cabot Corporation), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150, Color Black P160, Color Black P160, Color Black FW2V, Color Black FW200, Color Black FW200 Printex 140V, Special Black 6, Special Black 5, Special Black 4A, Special Black 4 (manufactured by Degussa), No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Corporation) and the like can be mentioned, but are not limited thereto.

  Specific examples of the cyan pigment include C.I. I. Pigment Blue-1, -2, -3, -15, -15: 1, -15: 2, -15: 3, -15: 4, -16, -22, -60, and the like. It is not limited.

  Specific examples of the magenta color pigment include C.I. I. Pigment Red-5, -7, -12, -48, -48: 1, -57, -112, -122, -123, -146, -168, -184, -202, and the like. It is not limited.

  Specific examples of yellow pigments include C.I. I. Pigment Yellow-1, -2, -3, -12, -13, -14, -16, -17, -73, -74, -75, -83, -93, -95, -97, -98, -114, -128, -129, -138, -151, -154, -180, and the like, but are not limited thereto.

  In the present invention, a pigment that is self-dispersible in water can also be used as a colorant. The pigment that can be self-dispersed in water refers to a pigment that has many water-solubilizing groups on the pigment surface and can be stably dispersed in water without the presence of a polymer dispersant. Specifically, it can be self-dispersed in water by subjecting ordinary so-called pigments to surface modification treatments such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, oxidation / reduction treatment, etc. Pigments are obtained.

  Further, as pigments that can be self-dispersed in water, in addition to pigments obtained by subjecting the above pigments to surface modification treatment, Cab-o-jet-200, Cab-o-jet-300, IJX- manufactured by Cabot Corporation Commercially available self-dispersing pigments such as 253, IJX-266, IJX-273, IJX-444, IJX-55, Microjet Black CW-1, CW-2 manufactured by Orient Chemical Co., etc. can also be used.

The self-dispersing pigment used in the present invention is preferably a pigment having at least sulfonic acid, sulfonate, carboxylic acid, or carboxylate as a functional group on the surface thereof.
Furthermore, a pigment coated with a resin can also be used. This is called a microcapsule pigment, and not only commercially available microcapsule pigments manufactured by Dainippon Ink and Chemicals, Inc., or Toyo Ink, but also microcapsule pigments produced for the present invention may be used. it can.
In addition, a resin-dispersed pigment in which a polymer material described later is chemically bonded to the pigment can also be used.

  The content of the color material contained in the first liquid according to the present invention is 0.1 mass% or more and 20 mass% or less, preferably 1 mass% or more and 10 mass% or less. When the content of the color material is less than 0.1% by mass, there is a case where a sufficient optical density cannot be obtained, and when the content is more than 20% by mass, the liquid ejection characteristics are unstable. There was a case.

The volume average particle diameter of the coloring material is preferably 30 nm or more and 250 nm or less. More preferably, they are 50 nm or more and 200 nm or less, More preferably, they are 75 nm or more and 175 nm or less. When the volume average particle diameter of the color material is less than 30 nm, the optical density may be low. On the other hand, when it exceeds 250 nm, the storage stability may not be ensured.
The volume average particle diameter of the color material refers to the particle diameter of the color material itself or the particle diameter to which the additive has adhered when an additive such as a dispersant is attached to the color material. In the present invention, a Microtrac UPA particle size analyzer 9340 (manufactured by Lees & Northrup) was used as a volume average particle diameter measuring apparatus. The measurement was performed according to a predetermined measurement method by putting 4 ml of the first liquid in a measurement cell. As parameters input at the time of measurement, the viscosity of the first liquid was input as the viscosity, and the density of the color material was input as the density of the dispersed particles.

―Polymer material―
In the present invention, the polymer substance used in the first liquid can be either a water-soluble resin or a water-dispersible resin, and can be any nonionic compound, anionic compound, cationic compound, or amphoteric compound. Absent. The polymer substance is used to disperse the color material or to promote aggregation of the color material.
As a specific example of the polymer substance, for example, a copolymer of a monomer having an α, β-ethylenically unsaturated group can be used. This copolymer may have any structure such as a random, block, or graft copolymer.

  Specific examples of the monomer having an α, β-ethylenically unsaturated group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid mono Ester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxyethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α -Styrene derivatives such as methylstyrene and vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylate, acrylic acid Niruesuteru, alkyl methacrylate, phenyl methacrylate, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl esters, maleic acid dialkyl ester and the like.

A homopolymer of the above monomer having an α, β-ethylenically unsaturated group or a copolymer obtained by copolymerizing a plurality of monomers is used as the polymer substance.
Specifically, styrene-styrene sulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl naphthalene- Methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, acrylic acid alkyl ester-acrylic acid copolymer, methacrylic acid alkyl ester-methacrylic acid copolymer, styrene-methacrylic acid alkyl ester-methacrylic acid copolymer, Styrene-acrylic acid alkyl ester-acrylic acid copolymer, styrene-methacrylic acid phenyl ester-methacrylic acid copolymer, styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer, sodium polyacrylate, carboxyvinyl polymer, etc. It is.

  Specific examples of the nonionic compound include, for example, polyoxyalkylene alkyl ether, polyoxyethylene alkylphenyl ether, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether, polyethylene glycol, polyethylene glycol laurate, and sorbit.

Specific examples of the cationic compound include, for example, N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminomethacrylamide, N, N-dimethylaminoacrylamide, and N-vinylpyrrole. , N-vinyl pyridine, N-vinyl pyrrolidone, N-vinyl imidazole, and other copolymers, monoalkylamine, monoalkyldimethylamine, alkylpropyldiamine, alkyldipropyltriamine, alkyltripropyltetramine, polyoxyethylene Examples thereof include alkylmethylbenzylammonium salt, alkylamine acetate, and tetraalkylammonium chloride.
Specific examples of amphoteric compounds include betaine type compounds.

  The polymer substance used in the present invention preferably has a mass average molecular weight of 2000 to 15000. When the molecular weight of the high molecular weight material is less than 2000, there are cases where the pigment is not stably dispersed. On the other hand, when the molecular weight exceeds 15000, the viscosity of the liquid is increased and the dischargeability is sometimes deteriorated. A more preferable mass average molecular weight is 3500 to 10,000.

  In the present invention, the second liquid may contain a polymer substance. When a high molecular substance is used for the second liquid, it is preferable to use a high molecular substance having a sulfonic acid, a sulfonic acid group, a carboxylic acid, or a carboxylic acid group as a functional group. More preferred are sulfonic acids and polymeric substances having sulfonic acid groups as functional groups. This is because long-term storage stability may be deteriorated when a dispersant having a carboxylic acid or a carboxylate salt as a functional group is used for the polymer substance.

The content of the polymer substance is used in the range of 0.1 mass% to 25 mass% for both the first liquid and the second liquid. When the addition amount exceeds 25% by mass, the liquid viscosity becomes high, and there are cases where the jetting characteristics of the liquid become unstable. On the other hand, when the addition amount was less than 0.1% by mass, good fixability could not be obtained. The addition amount of the polymer material is more preferably from 0.15% by mass to 2.5% by mass, and still more preferably from 0.2% by mass to 2% by mass.
Further, the content of the polymer substance in the first liquid is preferably 20 to 150% by mass, more preferably 25 to 120% by mass, and particularly preferably 30 to 100% by mass with respect to the content of the color material. If the content of the polymer material is 20 to 150% by mass with respect to the content of the color material, there is no nozzle non-ejection and good fixability of the color material to the recording medium can be obtained.

-Plasticizer-
In the present invention, a plasticizer is contained in at least one of the first liquid and the second liquid. As the plasticizer, known plasticizers for resins can be used without particular limitation. However, the plasticizer is formed into a film by being compatible with the polymer substance, and an image having excellent abrasion resistance is obtained. The difference between the SP value of the plasticizer and the SP value (solubility parameter) of the polymer material needs to be 2.0 or less in order to achieve the effect of the present application. When the difference in SP value is preferably 1.0 or less, more preferably 0.5 or less, the compatibility between the plasticizer and the polymer substance is further increased, and an image having excellent abrasion resistance can be obtained by film formation. Obtainable. Examples of the plasticizer include "Chemical Handbook" (edited by the Chemical Society of Japan, Maruzen), "Plasticizer-Theory and Application-" (edited by Koichi Murai, Koshobo), Can be selected with reference to "Under Research" (edited by Polymer Chemistry Association), "Handbook rubber / plastic compounded chemicals" (edited by Rubber Digest Co., Ltd.), etc.

In the present invention, a value obtained by the Fedors method is used as the SP value. The method of Fedors is described in Fedors, R .; F. , “Polymer Eng. Sci.”, 14. P. 147 (1974).
Specifically, it was calculated using the following formula.

  In the above formula, ΔE: cohesive energy density, V: molar volume, Δei: evaporation energy of atoms or atomic groups, Δvi: molar volume. Further, the value of the molar volume in the above formula is obtained as molecular weight / specific gravity. The specific gravity here uses the value at 25 ° C.

  Some plasticizers are described as high-boiling organic solvents and thermal solvents. For example, JP-A-59-83154, 59-178451, 59-178453, and 59-1-78454. 59-178455, 59-178457, 62-174754, 62-245253, 61-209444, 61-200538, 62-8145, 62-9348, 62-30247, 62-136646, 62-174754, 62-245253, 61-209444, 61-200538, 62-8145, 62-9348, 62 -30247, 62-136646, JP-A-2-235694, etc. Luric acid esters, phosphoric acid esters, fatty acid esters, abietic acid esters, adipic acid esters, sebacic acid esters, azelaic acid esters, benzoic acid esters, butyric acid esters, epoxidized fatty acid esters, glycol Acid esters, propionic acid esters, trimellitic acid esters, citric acid esters, sulfonic acid esters, carboxylic acid esters, succinic acid esters, maleic acid esters, fumaric acid esters, phthalic acid esters, And stearic acid esters), amides (for example, fatty acid amides, sulfoamides, etc.), ethers (MW 200 or more), alcohols (MW 200 or more), lactones, polyethyleneoxys, and the like.

  As the plasticizer, a polymer having a relatively low molecular weight can be used. In this case, the molecular weight of the plasticizer is 15000 or less, preferably 5000 or less. Furthermore, oligomers can also be used as plasticizers. In addition to the compounds listed above, commercially available products include, for example, Adeka Sizer PN-170, PN-1430 manufactured by Asahi Denka Kogyo; P. HALL products PARAPLEX-G-25, G-30, G-40; Rika Hercules products Ester gum 8L-JA, Ester R-95, Pentaline 4851, FK115, 4820, 830, Louisol 28-JA, Picolastic A75, Pico Examples include Tex LC and Crystallex 3085.

  Further, an aqueous solvent having an SP value of 8 to 11 such as butyl carbitol, diethylene glycol monoethyl ether, triethylene glycol or the like can be used as a plasticizer.

  The plasticizer used in the present invention is preferably at least one selected from the group consisting of aliphatic esters, acetic acid esters, trimellitic acid esters, and orthophosphoric acid esters, more preferably aliphatic esters, Tolu, dimethyl adipate and diethyl succinate are particularly preferred.

The mass mixing ratio of the polymer substance and the plasticizer is preferably 1: 0.005 to 1: 0.4 in the 1: 1 liquid mixture of the first liquid and the second liquid, and 1: 0.01. ˜1: 0.35 is more preferable, and 1: 0.03 to 1: 0.3 is particularly preferable.
If the mass mixing ratio of the polymer substance and the plasticizer is 1: 0.005 to 1: 0.4, good fixability of the color material to the recording medium can be obtained.

-Water-soluble solvent-
As the water-soluble solvent used in the present invention, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents and the like are used.
Specific examples of the water-soluble solvent include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, and glycerin. It is done.
Polyhydric alcohol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, diglycerin. And ethylene oxide adducts.

Examples of the nitrogen-containing solvent include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, and triethanolamine. Examples of the alcohol include alcohols such as ethanol, isopropyl alcohol, butyl alcohol, and benzyl alcohol.
Examples of the sulfur-containing solvent include thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like.
In addition, propylene carbonate, ethylene carbonate, or the like can be used.

  It is preferable to use at least one kind of water-soluble solvent used in the present invention. The content of the water-soluble organic solvent is 1 to 60% by mass, preferably 5 to 40% by mass. When the amount of the water-soluble solvent in the liquid is less than 1% by mass, a sufficient optical density may not be obtained. Conversely, when the amount is more than 60% by mass, the viscosity of the liquid increases. In some cases, the liquid ejection characteristics become unstable.

-Surfactant-
In the present invention, a surfactant can be added to each liquid as necessary. As the surfactant used in the present invention, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactants, cationic surfactants, amphoteric Either a surfactant or a nonionic surfactant can be used. Furthermore, the above-mentioned polymer substance can also be used.

  Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkylnaphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, sulfuric acid of higher alcohol ether. Ester salts and sulfonates, higher alkyl sulfosuccinates, higher alkyl phosphate esters, phosphate esters of higher alcohol ethylene oxide adducts, etc. can be used, such as dodecyl benzene sulfonate, keryl benzene sulfonate , Isopropyl naphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate, dibutylphenylphenol disulfonate, etc. That.

  Nonionic surfactants include, for example, polypropylene glycol ethylene oxide adduct, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, Examples include sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, aliphatic alkanolamide, glycerin ester, sorbitan ester and the like.

Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like, such as dihydroxyethyl stearylamine, 2-heptadecenyl-hydroxyethylimidazoline, Examples include lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridium chloride, and the like.
In addition, biosurfactants such as spicrispolic acid, rhamnolipid, and lysolecithin, carboxylate-type amphoteric surfactants such as sodium laurylaminopropionate, sulfate-type amphoteric surfactants, sulfonate-type amphoteric surfactants, phosphorus Acid ester salt type amphoteric surfactants can also be used.

  In the present invention, the amount of surfactant added to the liquid is preferably less than 10% by mass, more preferably 0.01% by mass to 5% by mass, and still more preferably 0.01% by mass to 3% by mass. Used in the following ranges. When the addition amount was 10% by mass or more, there were cases where the optical density and the storage stability of the pigment ink were deteriorated.

  In the present invention, as the flocculant used in the second liquid, it is preferable to use an acidic substance, an electrolyte, a cationic compound, or the like when a pigment having an anionic group on the surface thereof is contained as a coloring material. The pigment having an anionic group on the surface includes a self-dispersing colorant having an anionic group on the surface, and also includes a case where an anionic polymer substance is adsorbed on the surface of the pigment.

  Electrolytic flocculants include monovalent metal ions such as lithium ion, sodium ion, potassium ion, aluminum ion, barium ion, calcium ion, copper ion, iron ion, magnesium ion, manganese ion, nickel ion, tin ion, titanium Polyvalent metal ions such as ions and zinc ions, hydrochloric acid, odorous acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, and acetic acid, oxalic acid, lactic acid, fumaric acid, citric acid, salicylic acid, benzoic acid And the like, and organic carboxylic acids such as salts of organic sulfonic acids.

  Specific examples include aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, sodium aluminum sulfate, potassium aluminum sulfate, aluminum acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium nitrate, barium thiocyanate, Calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate, calcium tartrate, calcium lactate, calcium fumarate, citric acid Calcium, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, iron oxalate, iron lactate, iron fumarate, iron citrate, chloride Magnesium, Magnesium bromide Cium, magnesium iodide, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium lactate, manganese chloride, manganese sulfate, manganese nitrate, manganese dihydrogen phosphate, manganese acetate, manganese salicylate, manganese benzoate, manganese lactate, nickel chloride, odor Nickel fluoride, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, zinc thiocyanate, zinc acetate and other polyvalent metals, and lithium chloride, sodium chloride And salts of monovalent electrolytes such as potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, sodium sulfate, potassium nitrate, sodium acetate, potassium oxalate, sodium citrate and potassium benzoate.

  On the other hand, examples of the cationic compound include primary, secondary, tertiary and quaternary amines and salts thereof. Specific examples include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, polyamines, etc., for example, isopropylamine, isobutylamine, t-butylamine, 2-ethylhexylamine. , Nonylamine, dipropylamine, diethylamine, trimethylamine, monomethylamine, dimethylamine, triethylamine, dimethylpropylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, diethanolamine, diethylethanolamine, triethanolamine, tetra Methylammonium chloride, tetraethylammonium bromide, dihydroxyethyl stearylamine, - heptadecenyl - hydroxyethyl imidazoline, lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridinium chloride, diallyldimethylammonium chloride polymers, diallylamine polymers include monoallylamine polymer and the like.

  Preferred electrolytes are polyvalent metal salts such as aluminum sulfate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium acetate, tin sulfate, zinc chloride, zinc nitrate, zinc sulfate, Zinc acetate and aluminum nitrate, and preferred cationic compounds include monoallylamine polymers, diallylamine polymers, diallyldimethylammonium chloride polymers, and the like.

  In the present invention, the flocculant may be used alone or in combination of two or more. Moreover, as content of the coagulant | flocculant in a 2nd liquid, 0.01-15 mass% is preferable, More preferably, it is used at 0.1-10 mass%.

-Chelating agent-
It is also possible to add a chelating agent to the second liquid in order to reduce the interaction between the self-dispersing pigment and the flocculant in the second liquid and improve the storage stability. However, as the chelating agent used here, it is preferable to select a compound in which the chelating compound of the flocculant and the chelating agent becomes readily water-soluble.
Examples of the chelating agent that can be used in the present invention include ethylenediamine, ethylenediaminetetraacetic acid, 1,2-propylenediaminetetraacetic acid, 1-phenylethylenediaminetetraacetic acid, 3,3-dimethylbutane-1,2-diaminetetra. Acetic acid, 1,2,3-triaminopropanehexaacetic acid, trimethylenediaminetetraacetic acid, nitrilotriacetic acid, 1,2-cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, glycolethylenediaminetetraacetic acid, triethylenetetraminehexaacetic acid, triethylene Tetramine, tetraethylenepentamine, propane-1,2-diamine, butane-1,2-diamine, 3,3-dimethylbutane-1,2-diamine, 1,2,3-triaminopropane, trimethylenediamine, Tetralin , 3-diaminetetraacetic acid, decalin-2,3-tetraacetic acid, cyclohexane-1,2-diaminetetraacetic acid, cyclohexane-1,3-diaminetetraacetic acid, cyclohexane-1,4-diaminetetraacetic acid, oxalic acid, tyrone , Acetylacetone and the like, but are not limited thereto.

  Although not particularly limited, the solubility of the chelate compound formed by the flocculant and the chelating agent in water at 23 ° C. is preferably 0.1 g / L or more.

-Crosslinking agent-
In the inkjet ink set of the present invention, a crosslinking agent may be added.
The crosslinking agent is preferably added to the second liquid. In this case, the content of the crosslinking agent in the second liquid is preferably 0.05% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 25% by mass or less, and 0.3% by mass or more and 15% by mass. % Or less is particularly preferable.

In the second liquid, an antiionic additive (or an antiionic polymer) with respect to the polymer in the first liquid can be added in order to improve the cohesiveness and fixing property of the coloring material on the recording medium. .
Specific examples of the reverse ion additive include cationized cellulose, guar gum, casein, alkyl cation, amide quaternary cation, ester quaternary cation, and alkylamine oxide.

In the present invention, for the purpose of controlling characteristics such as improvement in ejection properties as needed in each liquid, cellulose derivatives such as polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose, polysaccharides and derivatives thereof , Other water-soluble polymers, acrylic polymer emulsions, polyurethane emulsions, polymer emulsions such as hydrophilic latex, hydrophilic polymer gels, cyclodextrins, macrocyclic amines, dendrimers, crown ethers, urea and its derivatives, acetamide, silicone A surface active agent, a fluorine based surface active agent and the like may be added.
In order to adjust the conductivity and pH of each liquid, compounds of alkali metals such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino- Use of nitrogen-containing compounds such as 2-methyl-1-propanol, alkaline earth metal compounds such as calcium hydroxide, acids such as sulfuric acid, hydrochloric acid and nitric acid, strong acid and weak alkali salts such as ammonium sulfate, etc. it can.
In addition, a pH buffer, an antioxidant, a fungicide, a viscosity modifier, a conductive agent, an ultraviolet absorber, and the like can be added as necessary.

As necessary, the first liquid and the second liquid include a carboxylate (sodium laurate, sodium stearate, etc.), a nitrate ester salt (sodium lauryl nitrate, sodium cetyl nitrate, etc.), a sulfonate ( Anionic compounds such as sodium benzenesulfonate may be added.
If necessary, alkylamine (monomethylamine, dimethylamine, etc.), pyridine, morpholine, etc. may be added to the first liquid and the second liquid.

-Third liquid-
The inkjet ink set of the present invention may further include a third liquid having a pH of 8 or more. The third liquid only needs to contain at least a pH adjuster and water, and may further contain the above-described color material, polymer substance, water-soluble solvent, flocculant, and the like as necessary.
Examples of the pH adjuster contained in the third liquid include alkaline substances such as NH ₃ , NaOH, KOH, and Na ₂ CO ₃ .
The pH in the present invention means a temperature of 23 ± 0.5 ° C. and a humidity of 55 ± 5% The value measured by a pH / conductivity meter (MPC227 manufactured by METTLER TOLEDO) under the H environment.

The surface tension of the first liquid containing carbon black as a coloring material is preferably 20 mN / m or more and 60 mN / m or less. More preferably, it is 22.5 mN or more and 45 mN / m or less, More preferably, it is 25 mN / m or more and 35 mN / m or less.
If the surface tension is less than 20 mN / m, the liquid may overflow on the nozzle surface and printing may not be performed normally. On the other hand, when it exceeds 60 mN / m, there are cases where the permeability is slow and the drying time is slow.
The surface tension of the first liquid containing an organic pigment as a coloring material is preferably 20 mN / m or more and 45 mN / m or less. More preferably, it is 22.5 mN or more and 40 mN / m or less, More preferably, it is 25 mN / m or more and 35 mN / m or less.
If the surface tension is less than 20 mN / m, the liquid may overflow on the nozzle surface and printing may not be performed normally. On the other hand, when it exceeds 45 mN / m, the permeability is slow, and the drying time may be slow.

  The viscosity of each liquid according to the ink jet ink set of the present invention is preferably 1.2 mPa · s or more and 8.0 mPa · s or less, more preferably 1.5 mPa · s or more and less than 6.0 mPa · s, and further Preferably, it is 1.8 mPa · s or more and less than 5.0 mPa · s. When the viscosity of each liquid was greater than 8.0 mPa · s, there was a case where the dischargeability was lowered. On the other hand, when it is smaller than 1.2 mPa · s, the long-term reliability sometimes deteriorated.

Next, a preferable aspect of the aggregate formed when the first liquid and the second liquid are mixed will be described.
The coarse particles present in the liquid mixture such as the aggregate containing the colorant formed when the first liquid and the second liquid are mixed will be described. Coarse particles of 5 μm or more present in the liquid mixture The number is preferably 500 / μL or more. More preferably, they are 500 pieces / microliter or more and 10,000 pieces / microliter or less, More preferably, they are 500 pieces / microliter or more and 3,000 pieces / microliter or less. When the number of coarse particles of 5 μm or more present in the mixed liquid of the first liquid and the second liquid is less than 500 / μL, the optical density of the formed image may be reduced.

In the present invention, the number of coarse particles of 5 μm or more in the mixed liquid of the first liquid and the second liquid is obtained by mixing two liquids at a mass ratio of 1: 1 and collecting 2 μL while stirring. Measurement was performed using an Accusizer ^™ 770 Optical Particle Sizer (trade name: manufactured by Particle Sizing Systems). In addition, as the parameter at the time of measurement, the density of the pigment aggregate was input as the density of the dispersed particles. The density of the pigment aggregate is determined based on the density of the pigment powder obtained by heating and drying the pigment aggregate dispersion obtained by mixing the first liquid and the second liquid. It can obtain | require by measuring using.

  The ink-jet ink set of the present invention is equipped with a recording device equipped with a heater or the like for controlling ink drying as well as a normal ink-jet recording device, or an intermediate transfer mechanism, and prints a recording material on the intermediate. Then, it can also be used in a recording apparatus that transfers to a recording medium such as paper.

<Inkjet recording method>
Next, the ink jet recording method of the present invention will be described. The inkjet recording method of the present invention contains at least a colorant, a polymer substance, a first liquid containing a water-soluble solvent, and water, at least a flocculant, a water-soluble solvent, and water. A second liquid, and an ink jet ink set that further contains a plasticizer in at least one of the first liquid and the second liquid, the first liquid, and the second liquid The liquid is applied on the recording medium so as to come into contact with each other to form an image. That is, the ink jet ink set of the present invention is used.
As the ink set for inkjet, an ink set further having a third liquid having a pH of 8 or more can be used.

When ink is applied on the recording medium, the first liquid and the second liquid are applied so that they contact each other. The second liquid is applied at a rate of 0.2 to 0.7 of the volume of the first liquid. This is because when the first liquid and the second liquid come into contact with each other, the ink aggregates due to the action of the aggregating agent, and the recording method is excellent in optical density, bleeding, intercolor bleeding, and drying time. There is no restriction | limiting in particular in the aspect which 2 types of liquids contact, For example, you may provide so that it may mutually adjoin, and you may provide so that the other may cover the application | coating area | region of one liquid.
Further, in the case of applying to the recording medium, the order in the case of sequentially applying the two liquids is arbitrary, but it is preferable to apply the first liquid after applying the second liquid. This is because by applying the second liquid first, the constituent components in the first liquid can be effectively aggregated. Further, the flocculant contained in the second liquid adheres onto the recording medium, so that the penetration of the coloring material into the recording medium can be suppressed.
After the second liquid is applied, the first liquid may be applied at any time, but the first liquid is added at a timing of 0.1 seconds or less after the second liquid is applied. It is preferable to give.
When the third liquid is used, it is preferable to apply the third liquid to a place where the first liquid and the second liquid are in contact with each other. Thereby, the polymer substance on the recording medium can be redissolved and the uniformity of the film can be improved. As a result, the fixing property is improved.
The timing for applying the third liquid is preferably within 0.01 to 1 second after the first liquid and the second liquid come into contact with each other.

In the recording method of the present invention, when ink is applied to a recording medium, the liquid mass per drop is preferably 25 ng or less for both the first liquid and the second liquid. More preferably, the liquid mass per drop of the first liquid is 0.5 ng or more and 20 ng or less, and more preferably 2 ng or more and 8 ng or less. On the other hand, the liquid mass per drop of the second liquid is not less than 0.5 ng and not more than 15 ng, and more preferably not less than 0.5 ng and not more than 4 ng. When the liquid mass per drop exceeded 25 ng, there was a case where bleeding deteriorated. This is because the contact angles of the first liquid and the second liquid with respect to the recording medium change depending on the drop amount, and the drop tends to spread toward the paper surface as the drop amount increases. ing.
In the recording method of the present invention, the liquid mass per drop of the third liquid used as necessary is preferably 0.01 to 0.5, more preferably 0.05 to 0.45 with respect to the first liquid. Further preferred is 0.1 to 0.4.
However, the drop amount in the ink jet apparatus capable of ejecting a plurality of drops from one nozzle refers to the minimum drop amount that can be printed.

In the present invention, the application amount of the first liquid required for forming one pixel is preferably 0.1 or more and 10 or less with respect to the application amount of the second liquid. More preferably, it is 0.2 or more and 5 or less. When the applied amount of the first liquid was less than 0.1 of the applied amount of the second liquid, there was a case where the aggregation was insufficient and the optical density was lowered. When it exceeded 10, deterioration of bleeding and deterioration of intercolor bleeding occurred.
In the present invention, so-called dark and light inks having different densities can be used for the first liquid and the second liquid. In that case, it is preferable to add a flocculant to the liquid having a low pigment concentration and use it as the second liquid. This is considered to be because the aggregation of the pigment can be suppressed and the storage stability can be improved by lowering the pigment concentration.

  Further, from the viewpoint of the effect of improving bleeding and intercolor bleeding, it is preferable to adopt a thermal ink jet recording method or a piezo ink jet recording method in applying ink. The cause of this is not clear, but in the case of the thermal ink jet recording method, the ink is heated at the time of ejection and has a low viscosity, but since the temperature of the ink is lowered on the recording medium, the viscosity rapidly increases. Become. For this reason, it is considered that bleeding and intercolor bleeding have an improving effect. On the other hand, in the case of the piezo ink jet method, it is possible to discharge a high-viscosity liquid, and the high-viscosity liquid can suppress spreading in the paper surface direction on the recording medium. It is estimated that there is an improvement effect on intercolor bleeding.

<Inkjet recording apparatus>
The ink jet recording apparatus of the present invention will be described below. An ink jet recording apparatus of the present invention is an ink jet recording apparatus provided with a recording head for ejecting each liquid in an ink jet ink set, wherein the ink jet ink set includes at least a coloring material, a polymer substance, and a water-soluble substance. A first liquid containing an organic solvent, water, and a second liquid containing at least a flocculant, a water-soluble solvent, and water, and the first liquid and the first liquid An ink-jet ink set that further contains a plasticizer in at least one of the two liquids is used.

Hereinafter, preferred embodiments of the ink jet recording apparatus of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. Although not shown in this example, an ink jet method in which the head is fixed at the paper width may be used.
FIG. 1 is a perspective view showing an external configuration of a preferred embodiment of an ink jet recording apparatus (image forming apparatus) according to the present invention. FIG. 2 is a perspective view showing the basic internal configuration of the image forming apparatus shown in FIG.
The image forming apparatus 100 of the present embodiment has a configuration that operates based on the above-described image forming method (inkjet recording method) of the present invention to form an image. That is, as shown in FIGS. 1 and 2, an image forming apparatus 100 mainly includes an external cover 6, a tray 7 on which a predetermined amount of recording medium 1 such as plain paper can be placed, and the recording medium 1 as an image forming apparatus. A conveying roller (conveying means) 2 for conveying the sheet 100 inside one by one, and an image forming unit 8 (image forming means) for forming an image by ejecting ink and a liquid composition onto the surface of the recording medium 1. Have.

The conveyance rollers 2 are a pair of rollers rotatably disposed in the image forming apparatus 100, sandwiching the recording medium 1 set on the tray 7 and one sheet of a predetermined amount of recording medium 1 at a predetermined timing. Each time it is conveyed into the image forming apparatus 100.
The image forming unit 8 forms an image with ink on the surface of the recording medium 1. The image forming unit 8 mainly includes a recording head 3, an ink tank 5, a power supply signal cable 9, a carriage 10, a guide rod 11, a timing belt 12, a driving pulley 13, and a maintenance unit 14. Yes.
In this aspect, the ink tank 5 has a plurality of ink tanks 52, 54, 56, 58 in which a first liquid, a second liquid, and a third liquid used as needed are stored so as to be ejectable. Yes.

  Further, as shown in FIG. 2, a power feeding signal cable 9 and an ink tank 5 are connected to the recording head 3, and when external image recording information is input to the recording head 3 from the power feeding signal cable 9, the recording head 3 sucks a predetermined amount of ink from each ink tank based on the image recording information and discharges the ink onto the surface of the recording medium. The power supply signal cable 9 also has a role of supplying power necessary for driving the recording head 3 to the recording head 3 in addition to the image recording information.

  The recording head 3 is arranged and held on a carriage 10, and the carriage 10 is connected to a guide rod 11 and a timing belt 12 connected to a driving pulley 13. With such a configuration, the recording head 3 extends along the guide rod 11 and is parallel to the surface of the recording medium 1 and perpendicular to the conveyance direction X (sub-scanning direction) of the recording medium 1 (main scanning direction). It can also be moved in the scanning direction.

  The image forming apparatus 100 includes control means (not shown) that adjusts the drive timing of the recording head 3 and the drive timing of the carriage 10 based on the image recording information. Thereby, an image based on the image recording information can be continuously formed in a predetermined region of the surface of the recording medium 1 that is transported at a predetermined speed along the transport direction X.

The maintenance unit 14 is connected to the decompression device via the tube 15. Further, the maintenance unit 14 is connected to the nozzle portion of the recording head 3, and the nozzles of the recording head 3 are reduced by reducing the pressure in the nozzle of the recording head 3 with a vacuum pump (not shown) provided at the connecting portion. From the ink.
By providing the maintenance unit 14, it is possible to remove excess ink adhering to the nozzle while the image forming apparatus 100 is in operation, or to suppress evaporation of ink from the nozzle when the operation is stopped. Can do. However, since the first liquid and the second liquid are mixed to produce an aggregate, the maintenance unit 14 having a configuration in which the first liquid and the second liquid are separately accommodated is preferable. .

As the recording head, it is preferable to use a thermal ink jet method or a piezo ink jet method.
The recording head used here is preferably a member that can apply the first ink and the second ink to the recording medium at a weight of 25 ng or less per drop. In the present invention, it is also possible to use an ink jet recording apparatus that can eject a plurality of drops of volume from one nozzle. In such an apparatus, the weight of the one drop is: It refers to the drop amount of the smallest drop that can be printed.
Furthermore, the recording head applies the first liquid applied to form one pixel so that the applied amount of the first liquid is in the range of 0.1 to 10 with respect to the applied amount of the second liquid. It is a preferable aspect that it is a member which can be. More preferably, it is 0.2 or more and 5 or less.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Pigment treatment method>
The aqueous sulfanilic acid (5%) solution was heated, and 100 parts by mass of the pigment was added with stirring. The mixture was cooled to room temperature with stirring, and 14 parts by mass of concentrated nitric acid was added dropwise. To this solution, 10 parts by mass of NaNO ₂ aqueous solution was added and stirred until the reaction was completed. The pigment was desalted. The obtained surface-treated pigment was added with ion-exchanged water so that the pigment concentration was 12% by mass, adjusted to pH 7.5, and then dispersed using an ultrasonic homogenizer. This dispersion was subjected to centrifugal separation (8000 rpm × 30 minutes) with a centrifugal separator to remove the residue (20% of the total amount).

<Liquid preparation method>
Appropriate amounts of a coloring material solution, a water-soluble solvent, a surfactant, ion-exchanged water, and the like were added so as to obtain a predetermined composition, and the mixture was mixed and stirred. The obtained liquid was passed through a 5 μm filter to obtain a desired liquid.

(First liquid A)
Cabojet-300 (manufactured by Cabot)
(Self-dispersing pigment / carboxylic acid group) 4% by mass
Styrene-acrylic acid (35/65) copolymer (Mw. 10200, SP value 10.8)
2% by mass
Diethylene glycol 10% by mass
Glycerin 5% by mass
2-pyrrolidone 5% by mass
Acetylene glycol ethylene oxide adduct 0.2% by mass
Ion exchange water balance

(First liquid B)
A pigment treated according to the pigment treatment method was used.
C. I. Pigment Blue 15: 3
(Self-dispersing pigment / sulfonic acid group) 3% by mass
Styrene-sodium maleate (30/70) copolymer (Mw. 9100, SP value 11.1)
2.5% by mass
Diethylene glycol 15% by mass
Triethylene glycol monobutyl ether 5% by mass
Acetylene glycol ethylene oxide adduct 0.9 mass%
Calcium chloride 0.075% by mass
Ion exchange water balance

(First liquid C)
A pigment treated according to the pigment treatment method was used.
C. I. Pigment Red 122
(Self-dispersing pigment / sulfonic acid group) 4% by mass
n-Butyl methacrylate-sodium methacrylate (43/57) copolymer (Mw. 11000, SP value 10.9) 2.5% by mass
Diethylene glycol 10% by mass
Diethylene glycol monobutyl ether 5% by mass
Glycerin 5% by mass
Acetylene glycol ethylene oxide adduct 1.2% by mass
Calcium nitrate 0.1% by mass
The balance of the ion-exchanged water The liquid had a ζ potential of −13 mV, a volume average particle size of 118 nm, a viscosity of 3.3 mPa · s, and a surface tension of 31 mN / m.

(First liquid D)
A pigment treated according to the pigment treatment method was used.
C. I. Pigment Yellow 74
(Self-dispersing pigment / sulfonic acid group) 4% by mass
2-ethylhexyl methacrylate-sodium methacrylate (65/35) copolymer (Mw. 12500 SP value 11.0) 0.3% by mass
Diethylene glycol 15% by mass
N-methyl-2-pyrrolidone 5% by mass
Urea 6% by mass
Acetylene glycol ethylene oxide adduct 1% by mass
Calcium nitrate 0.1% by mass
Glycolethylenediaminetetraacetic acid 0.05% by mass
Ion exchange water balance

(Second liquid A)
Diethyl succinate (SP value 9.2) 5% by mass
Diethylene glycol 30% by mass
Acetylene glycol ethylene oxide adduct 1% by mass
Magnesium nitrate 0.1% by mass
Ion exchange water remainder The viscosity of this liquid was 3.2 mPa · s, and the surface tension was 31 mN / m.

(Second liquid B)
Diethylene glycol 30% by mass
Acetylene glycol ethylene oxide adduct 1% by mass
Magnesium nitrate 0.1% by mass
The balance of the ion-exchanged water The viscosity of this liquid was 3.0 mPa · s, and the surface tension was 29 mN / m.

(Third liquid)
Diethylene glycol 30% by mass
Acetylene glycol ethylene oxide adduct 1% by mass
Sodium hydroxide 10% aqueous solution 0.1% by mass
The remainder of the ion-exchanged water had a viscosity of 3.0 mPa · s, a surface tension of 29 mN / m, and a pH of 9.5.

<Evaluation method by printing>
A prototype printer having a plurality of prototype print heads with 800 dpi, 256 nozzles and a maintenance unit for storing a plurality of inks alone was used. On the FX-P paper (manufactured by Fuji Xerox Co., Ltd.), the first, second, and, if necessary, third liquids were printed in this order in the combinations shown in Table 1. The discharge amount of the first liquid was 8 pl, and the discharge amounts of the second and third liquids were 4 pl. Unless otherwise specified, printing is performed in a general environment (temperature 23 ± 0.5 ° C., humidity 55 ± 5% RH), and evaluation is performed on samples left in the general environment for 24 hours after printing. I went.
The obtained results are shown in Table 1.

(Abrasion resistance)
After 30 minutes of printing, ink-jet coated paper, high grade, C2 plain paper (manufactured by Fuji Xerox Co., Ltd.) was rubbed from the solid part to the unprinted white area, and the stain transferred to the white part was visually observed.
-Evaluation criteria-
◯: There is almost no dirt on the white part. △: There is some dirt on the white part. X: There is considerable dirt on the white part.

(Blending between colors)
For the evaluation of intercolor bleeding, a 9-point MS Mincho character in black and a yellow solid sample as a background are printed, and the degree of bleeding at the boundary is collated with a predetermined limit sample, and a sensory evaluation is performed. It was.
-Evaluation criteria-
○… Bleeding is less △… Bleeding has occurred but is at an acceptable level ×… Bleeding is severe and is outside the allowable range

(Optical density)
The optical density of the printed portion was measured using X-Rite 404 (manufactured by X-Rite).
-Evaluation criteria (black ink)-
○… Optical density is 1.4 or more △… Optical density is 1.3 or more and less than 1.4 ×… Optical density is less than 1.3

  As apparent from Table 1, when the ink jet ink set of the present invention is used, an image excellent in abrasion resistance can be obtained.

1 is a perspective view showing an external configuration of a preferred embodiment of an ink jet recording apparatus according to the present invention. FIG. 2 is a perspective view showing an internal basic configuration of the ink jet recording apparatus of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording medium 2 Conveyance roller 3 Recording head 5 Ink tank 6 External cover 7 Tray 8 Image formation part 9 Power supply signal cable 10 Carriage 11 Guide rod 12 Timing belt 13 Drive pulley 14 Maintenance unit 15 Tube

Claims (15)

A first liquid containing at least a coloring material, a polymer substance, a water-soluble solvent, and water;
A second liquid containing at least a flocculant, a water-soluble solvent, and water;
An ink-jet ink set, further comprising a plasticizer in at least one of the first liquid and the second liquid.   The inkjet ink set according to claim 1, wherein a difference between an SP value of the plasticizer and an SP value of the polymer substance is 2.0 or less.   The mass mixing ratio of the polymer substance and the plasticizer in the 1: 1 liquid mixture of the first liquid and the second liquid is 1: 0.005 to 1: 0.4. Item 2. The inkjet ink set according to Item 1.   2. The inkjet ink set according to claim 1, wherein a content of the polymer substance in the first liquid is 20 to 150 mass% with respect to a content of the coloring material.   The inkjet ink set according to claim 1, further comprising a third liquid having a pH of 8 or more. An inkjet recording apparatus including a recording head for ejecting each liquid in an inkjet ink set,
The ink-jet ink set includes at least a colorant, a polymer substance, a first liquid containing a water-soluble solvent, and water, at least a flocculant, a water-soluble solvent, and water. And a second liquid, and at least one of the first liquid and the second liquid further contains a plasticizer.   The inkjet recording apparatus according to claim 6, wherein a difference between an SP value of the plasticizer and an SP value of the polymer substance is 2.0 or less.   The mass mixing ratio of the polymer substance and the plasticizer in the 1: 1 liquid mixture of the first liquid and the second liquid is 1: 0.005 to 1: 0.4. Item 7. The ink jet recording apparatus according to Item 6.   The inkjet recording apparatus according to claim 6, wherein a content of the polymer substance in the first liquid is 20 to 150% by mass with respect to a content of the color material.   The inkjet recording apparatus according to claim 6, wherein the inkjet ink set further includes a third liquid having a pH of 8 or more.   A first liquid containing at least a coloring material, a polymer substance, a water-soluble solvent, and water; and a second liquid containing at least a flocculant, a water-soluble solvent, and water. And an ink jet ink set that further contains a plasticizer in at least one of the first liquid and the second liquid, and the first liquid and the second liquid are in contact with each other. An ink jet recording method in which an image is formed on a recording medium.   The inkjet recording method according to claim 11, wherein a difference between an SP value of the plasticizer and an SP value of the polymer substance is 2.0 or less.   The mass mixing ratio of the polymer substance and the plasticizer in the 1: 1 liquid mixture of the first liquid and the second liquid is 1: 0.005 to 1: 0.4. Item 12. The inkjet recording method according to Item 11.   12. The ink jet recording method according to claim 11, wherein the content of the polymer substance in the first liquid is 20 to 150 mass% with respect to the content of the coloring material.   The inkjet ink set further includes a third liquid having a pH of 8 or more, and the recording medium is such that the first liquid, the second liquid, and the third liquid are in contact with each other. The inkjet recording method according to claim 11, wherein the inkjet recording method is applied to form an image.

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