JP2017007297A - Inkjet printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printing method where an image is printed by an inkjet recording system using nonaqueous pigment ink at least including a pigment and a non-water-soluble organic solvent, and thereafter, a post-treatment liquid is printed on the image so as to be piled, while securing high printing density by suppressing the infiltration to the inside of the printing medium of the pigment is suppressed, the scratch resistance of a printed matter can be improved.SOLUTION: Provided is an inkjet printing method using a water-in-oil water (W/O) type emulsion, which includes silica as a post-treatment liquid in an oil phase and a water soluble resin having an amino group in a water phase. The water-soluble resin included in the post-treatment liquid is preferably being polyethyleneimine, and the average molecular weight of the polyethyleneimine is preferably being 500 to 50,000.SELECTED DRAWING: None

Description

  The present invention relates to an ink jet printing method for performing printing by an ink jet recording method using a non-aqueous pigment ink, which can improve the scratch resistance of a printed matter while ensuring a print density.

  Inkjet recording is a method in which high-fluidity inkjet ink is ejected as ink particles from fine head nozzles, and an image is recorded on printing paper placed facing the nozzles, enabling high-speed printing with low noise. Therefore, it has been spreading rapidly in recent years. As inks used in such an ink jet recording system, various so-called oil-based ink jet inks in which pigments are dispersed in a non-aqueous solvent have been proposed.

  As the oil-based inkjet ink as described above, the applicant of the present application is a non-aqueous pigment ink containing a pigment, a water-insoluble resin, and a water-soluble resin in a non-aqueous solvent, wherein the water-soluble resin is a polyethyleneimine. A non-aqueous pigment ink is proposed (see Patent Document 1). This ink has the advantage of realizing low ink viscosity and excellent storage stability (pigment dispersion stability), and at the same time, it can suppress show-through and achieve high printing density. .

  By the way, in the recording method using the oil-based ink-jet ink, the scratch resistance of the printed matter may be a problem. This is because the oil-based ink itself does not dry and solidify, but is a penetrating drying type ink that penetrates into a printed matter such as paper and dries. However, in the recording method using the oil-based inkjet ink of Patent Document 1 described above, the pigment tends to stay on the surface of the printed material, so that a high printing density is realized, but the scratch resistance may be deteriorated.

  On the other hand, the applicant of the present application forms a dot made of non-aqueous pigment ink by discharging a droplet of non-aqueous pigment ink onto the surface of the print medium, and then a non-aqueous post-treatment liquid containing at least silica and an organic solvent. In the non-aqueous ink jet printing method including a step of ejecting droplets toward a printing medium so as to overlap the dots made of the non-aqueous pigment ink, an amino group is added to either the non-aqueous pigment ink or the post-treatment liquid. It has already been proposed to improve the printing density by containing a water-soluble resin having a pigment (see Japanese Patent Application No. 2013-272449). However, this printing method does not take into consideration the improvement of scratch resistance.

JP 2014-15491 A

  An object of the present invention is to provide a method capable of improving the scratch resistance of printed matter while ensuring high printing density by suppressing the penetration of pigment into the printing medium in the ink jet printing method using the oil-based ink jet ink as described above. It is to provide.

  As a result of earnest research conducted by the inventor for the above purpose, the present inventor includes a non-aqueous ink jet printing method in which a non-aqueous pigment ink is ejected onto the surface of a printing medium to print an image and then a post-treatment liquid is printed on the image In the printing method, as the post-treatment liquid, by using a water-in-oil (W / O) emulsion containing silica in the oil phase and a water-soluble resin having an amino group in the water phase, a high printing density can be obtained. While ensuring, it discovered that the abrasion resistance of printed matter could be improved, and came to complete this invention.

  That is, according to the present invention, after printing an image by an ink jet recording method using a non-aqueous pigment ink containing at least a pigment and a water-insoluble organic solvent, an ink jet printing method for printing a post-treatment liquid on the image. An ink jet printing method is provided in which the post-treatment liquid is a water-in-oil (W / O) emulsion containing silica in an oil phase and a water-soluble resin having an amino group in the water phase. Is done.

  According to the present invention, after forming an image by ink-jet printing a non-aqueous pigment ink on a printing medium, a post-treatment liquid composed of a water-in-oil (W / O) emulsion is printed over the image, and then post-processing is performed. The liquid oil phase penetrates into the print medium and mixes with the ink, and the hydroxyl group on the silica surface binds to the dispersant on the pigment surface, and the dispersion stability of the pigment and silica collapses and agglomerates, causing the pigment to adhere to the surface of the print medium. It is considered that the printing density tends to stay close and the printing density is maintained high. After that, when the aqueous phase is absorbed into the printing medium, the emulsion breaks down, and the polyethyleneimine in the aqueous phase coats the surface of the printing medium, improving the scratch resistance of the printed matter while maintaining the printing density. It is thought to do.

  Hereinafter, the present invention will be described in more detail.

1. Non-aqueous pigment ink The non-aqueous pigment ink used in the present invention comprises at least a pigment and a water-insoluble organic solvent, and if necessary, other pigment dispersants (non-aqueous resins), water-soluble resins, and the like. You may contain a component.

1-1. As the pigment , organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments, dyed lake pigments, and inorganic pigments can be used. Examples of the azo pigments include soluble azo lake pigments, insoluble azo pigments, and condensed azo pigments. Examples of phthalocyanine pigments include metal phthalocyanine pigments and metal-free phthalocyanine pigments. Polycyclic pigments include quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, isoindolinone pigments, dioxysazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments. And diketopyrrolopyrrole (DPP). Representative examples of inorganic pigments include carbon black and titanium oxide. These pigments may be used alone or in combination of two or more.

  The content of the pigment in the non-aqueous pigment ink used in the present invention is usually 0.01 to 20% by mass with the total amount of ink being 100% by mass, and 1 to 15% by mass from the viewpoint of printing density and ink viscosity. It is preferably 5 to 10% by mass.

  The average particle diameter of the pigment in the non-aqueous pigment ink used in the present invention is preferably 500 nm or less, and more preferably 150 nm or less, from the viewpoints of dispersibility and storage stability. Here, the average particle diameter of the pigment is a volume-based value measured by a dynamic light scattering particle size distribution analyzer LB-500 manufactured by Horiba, Ltd.

1-2. Water-insoluble organic solvent As the water-insoluble organic solvent, any of a non-polar organic solvent and a polar organic solvent can be used. These may be used alone or in combination.

  Preferable examples of the nonpolar organic solvent include petroleum hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents. Examples of the aliphatic hydrocarbon solvent and the alicyclic hydrocarbon solvent include water-insoluble organic solvents such as paraffinic, isoparaffinic, and naphthenic solvents, and commercially available products include 0 Solvent L and 0 Solvent M. No. 0 solvent H, Cactus normal paraffin N-10, Cactus normal paraffin N-11, Cactus normal paraffin N-12, Cactus normal paraffin N-13, Cactus normal paraffin N-14, Cactus normal paraffin N-15H, Cactus normal paraffin N-15 Paraffin YHNP, Cactus normal paraffin SHNP, Isosol 300, Isosol 400, Teclean N-16, Teclean N-20, Teclean N-22, AF Solvent No. 4, AF Solvent No. 5, AF Solvent No. 6, AF Solvent No., Naphthezol 160, Naphthezol 200, Naphthezol 220 (all trade names manufactured by JX Nippon Oil & Energy Corporation); Isopar G, Isopar H, Isopar L, Isopar M, Exol D40, Exol D60, Exol D80, Exol D95, Exol D110, Exole D130 (both are trade names manufactured by TonenGeneral Sekiyu KK) and the like can be preferably exemplified. As the aromatic hydrocarbon solvent, grade alkene L, grade alkene 200P (all are trade names manufactured by JX Nippon Oil & Energy Corporation), Solvesso 100, Solvesso 150, Solvesso 200, Solvesso 200ND (all are TonenGeneral Sekiyu KK) The product name of the product and the like can be preferably mentioned. The distillation initial boiling point of the petroleum hydrocarbon solvent is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and even more preferably 200 ° C. or higher. The distillation initial boiling point can be measured in accordance with JIS K0066 “Method for Distillation Test of Chemical Products”.

  Preferred examples of the polar organic solvent include fatty acid ester solvents, higher alcohol solvents, higher fatty acid solvents and the like. For example, isononyl isononanoate, isodecyl isononanoate, methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, hexyl palmitate, isooctyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate , Isopropyl oleate, butyl oleate, hexyl oleate, methyl linoleate, ethyl linoleate, isobutyl linoleate, butyl stearate, hexyl stearate, isooctyl stearate, isopropyl isostearate, 2-octyldecyl pivalate, soybean oil Methyl, soybean oil isobutyl, tall oil methyl, tall oil isobutyl, etc., the number of carbon atoms in one molecule is 13 or more, preferably 16-30 fatty acid esters Agents: Higher alcohol solvents having 6 or more, preferably 12 to 20 carbon atoms in one molecule, such as isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, oleyl alcohol, isoeicosyl alcohol, decyltetradecanol; Higher fatty acid solvents such as lauric acid, isomyristic acid, palmitic acid, isopalmitic acid, α-linolenic acid, linoleic acid, oleic acid, isostearic acid and the like having 12 or more, preferably 14 to 20 carbon atoms in one molecule Is mentioned. The boiling point of polar organic solvents such as fatty acid ester solvents, higher alcohol solvents and higher fatty acid solvents is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 250 ° C. or higher. preferable. The water-insoluble organic solvent having a boiling point of 250 ° C. or higher includes a water-insoluble organic solvent having no boiling point.

  These water-insoluble organic solvents may be used alone or in combination of two or more as long as a single phase is formed.

1-3. Pigment Dispersant The non-aqueous pigment ink according to the present invention preferably contains a pigment dispersant in order to ensure the dispersion stability of the pigment.
The pigment dispersant that can be used in the present invention is not particularly limited as long as the pigment is stably dispersed in a water-insoluble organic solvent. For example, a hydroxyl group-containing carboxylic acid ester, a long-chain polyaminoamide, and a high molecular weight acid are used. Ester salt, high molecular weight polycarboxylic acid salt, long chain polyaminoamide and polar acid ester salt, high molecular weight unsaturated acid ester, high molecular weight copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activity Agent, naphthalenesulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl phenyl ether, polyester polyamine, stearylamine acetate, etc. are preferably used, of which compounds having an amino group, particularly amino groups Use a polymer dispersant with Preferred.

  The total amount of the pigment dispersant is preferably 0.2 to 1.0 with respect to the pigment 1.

  The blending amount of the pigment dispersant is preferably 1 to 15% by mass and more preferably 2 to 10% by mass with respect to 100% by mass of the total amount of the ink.

1-4. Other Ink Components The non-aqueous pigment ink according to the present invention may contain conventional additives in addition to the above components. Additives include surfactants such as anionic, cationic, amphoteric or nonionic surfactants, antioxidants such as dibutylhydroxytoluene, propyl gallate, tocopherol, butylhydroxyanisole, and nordihydroguaiare. Examples include tic acid.

1-5. In the case of an ink jet recording system, the viscosity range of the ink varies depending on the nozzle diameter of the discharge head, the discharge environment, and the like, but in general, the viscosity is preferably 5 to 30 mPa · s at 23 ° C. More preferably, it is about 15 mPa · s, and about 10 mPa · s is suitable for an inkjet recording apparatus.

1-6. Ink Preparation Method The method for preparing the non-aqueous pigment ink is not particularly limited, and it can be prepared by mixing a pigment and, if necessary, other components in a water-insoluble organic solvent.

2. Post-treatment liquid The post-treatment liquid used in the present invention comprises a water-in-oil (W / O) emulsion containing silica in the oil phase and a water-soluble resin having an amino group in the water phase.

2-1. Oil phase
2-1-1. As the solvent constituting the solvent oil phase, the water-insoluble organic solvents described for the non-aqueous pigment ink can be used. Among these, it is preferable to use a non-polar organic solvent, particularly a petroleum hydrocarbon solvent such as an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, an aromatic hydrocarbon solvent, etc. from the viewpoint of emulsion formation.

2-1-2. The silica silica is not particularly limited, powdered silica, colloidal silica, and synthetic amorphous silica. These can be used alone or in combination of two or more. Examples of the powder silica include AEROSIL 90, OX 50, R106 (all trade names) manufactured by Nippon Aerosil Co., Ltd., E-200A, E-220A, K-500, E-1009 manufactured by Tosoh Silica Co., Ltd. E-1011, E-1030, E-150J, E-170 (all are trade names), etc. can be used. Examples of colloidal silica include Snowtex S, OS, XS, OXS, 20, 30, 40, 50, O, AK, AK-YL, O-40, CM, 20L, C, manufactured by Nissan Chemical Industries, Ltd. ZL, XL, N, UP (all trade names), Quotron PL-1, PL-3, PL-7, PL-20 (all trade names) manufactured by Fuso Chemical Industry Co., Ltd., Sanko Colloid Chemical Co., Ltd. ) Silicaroid, Silicaloid-LL, Silicaloid-A (both trade names) and the like can be used. Synthetic amorphous silica is formed by neutralization reaction of silicate and acid, and can be divided into various properties depending on the production method thereof. For example, Mizusuka Chemical Co., Ltd. Mizukasil P-73, P- 78A, P-707, P-709, P-527, P-803 (all of which are trade names) can be used.

  The average particle size of silica is preferably 10 to 400 nm, and more preferably 15 to 300 nm. When the average particle diameter of the silica is in this range, the back-through can be further reduced and a high printing density can be obtained. Here, the average particle diameter of silica is a volume-based value measured by a dynamic light scattering particle size distribution measuring device LB-500 manufactured by Horiba, Ltd.

  As content of the silica in an oil phase, 1-20 mass% is preferable in conversion of solid content, and it is more preferable that it is 5-20 mass%. In the range of 1 to 20% by mass, it is possible to sufficiently obtain the effects of reducing the back-through and improving the printing density, preventing the irregular reflection of light on the printing medium, and dispersing the silica in the post-treatment agent. Stability can be maintained well.

2-1-3. Other oil phase components In the oil phase, a pigment dispersant, an antioxidant, a preservative, and the like can be contained as necessary. As the pigment dispersant, those described above for the non-aqueous pigment ink can be used.

2-2. Water phase
2-2-1. The solvent constituting the solvent aqueous phase may be composed only of water, or may contain a water-soluble organic solvent in addition to water. Examples of water include tap water, ion exchange water, and deionized water. As the water-soluble organic solvent, an organic compound that is liquid at room temperature and is soluble in water can be used, and a water-soluble organic solvent that is uniformly mixed with the same volume of water at 1 atm 20 ° C. is preferably used. . For example, lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, 2-methyl-2-propanol; ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene Glycols such as glycol, propylene glycol, dipropylene glycol, tripropylene glycol and polypropylene glycol; glycerols such as glycerin, diglycerin, triglycerin and polyglycerin; acetins such as monoacetin, diacetin and triacetin; ethylene glycol monomethyl ether; Ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobuty Ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether Glycol ethers such as ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether; triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β -Use thiodiglycol, sulfolane, etc. Can be. The boiling point of the water-soluble organic solvent is preferably 100 ° C. or higher, and more preferably 150 ° C. or higher.

  These water-soluble organic solvents may be used alone or in combination of two or more as long as they form a single phase with water. The content of the water-soluble organic solvent in the ink is preferably 5 to 50% by mass and more preferably 10 to 35% by mass as the total content when two or more types are used.

2-2-2. Examples of the water- soluble resin having an amino group to be contained in the aqueous phase having an amino group include basic polymer electrolytes such as polyethyleneimine (PEI), polyvinylamine, and polyvinylpyridine, or derivatives thereof. In particular, it is preferable to use polyethyleneimine having a number average molecular weight of 300 to 70000, or modified polyethyleneimine obtained by addition reaction with polyethyleneimine having a number average molecular weight of 300 to 70000 and either an acrylate ester or a vinyl compound. it can. The modified polyethyleneimine preferably has a ratio of 0.3 mol equivalent to less than 1 mol equivalent with respect to the acrylic ester or vinyl compound when the total amine value of polyethyleneimine is 1 mol equivalent. Here, the amine value is determined by the amine titration method (KOHmg / g) by (2) indicator titration method of JIS K-7237-1995 (total amine value test method for amine curing agent of epoxy resin), and the molecular weight of KOH is 56. It is calculated in terms of 11 mg / mmol.

  When the number average molecular weight of the polyethyleneimine is in the range of 300 to 70000, the effect of increasing the density with respect to plain paper is high, and the storage stability is also good. The number average molecular weight of polyethyleneimine is more preferably 500 to 50,000, which has a large effect of improving scratch resistance.

  As the polyethyleneimine, commercially available products can be used. For example, EPOMIN SP-003, SP-006, SP-012, SP-018, SP-200, SP-1000, manufactured by Nippon Shokubai Co., Ltd .; BASF (stock) And Lupasol FG, Lupasol G20 Waterfree, Lupasol PR8515 and the like.

  The content of the water-soluble resin having an amino group is preferably 10 to 80% by mass, and more preferably 20 to 75% by mass with respect to 100% by mass of the entire aqueous phase. Moreover, it is preferable that the content rate of the water-soluble resin which has an amino group is 10-30 mass% with respect to 100 mass% of the whole ink.

2-2-3. Other aqueous phase components In the aqueous phase, surface tension adjusters (penetrating agents), antifoaming agents, antioxidants, pH adjusting agents, preservatives, wetting agents (humectants), fixing agents, etc., as necessary Can be contained.

2-3. Preparation method of post- treatment liquid The post-treatment liquid is prepared by mixing silica and other components with a water-insoluble organic solvent that is a solvent constituting the oil phase to obtain an oil phase, while water that is a solvent constituting the aqueous phase. It can be produced by mixing a water-soluble resin having an amino group and other components to obtain an aqueous phase, and then mixing and emulsifying the oil phase and the aqueous phase. You may emulsify, adding the water phase to the oil phase under stirring sequentially. In order to achieve both the stability of the emulsion and the scratch resistance of the printed matter, the post-treatment liquid is composed of 10 to 30% by mass of the aqueous phase and 70 to 90% by mass of the oil phase as a total of 100% by mass of the oil phase and the aqueous phase. It is preferred that For emulsification, an emulsifier such as a disper mixer or a homomixer can be used. In this case, it is usually preferable to contain an emulsifier in the oil phase.

  The emulsifier is not particularly limited as long as it can form a water-in-oil (W / O) emulsion, but a nonionic surfactant is preferably used. Nonionic surfactants include, for example, sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan sesquioleate, fatty acid glycerides, polyglycerin Examples thereof include fatty acid esters, fatty acid diglycerides, and ethylene oxide adducts such as higher alcohols, alkylphenols, and fatty acids.

  The use amount of the emulsifier is preferably 0.5 to 40% by mass, more preferably 1.0 to 15% by mass, more preferably 100% by mass, based on the total amount of the post-treatment liquid. Is 2.0-12 mass%. When the amount used is in the range of 0.5 to 40% by mass, the storage stability of the emulsion becomes good, and the viscosity is suitable for inkjet applications.

2-4. Properties of the post-treatment liquid In the case of an inkjet recording system, the viscosity of the post-treatment liquid varies depending on the nozzle diameter of the ejection head, the ejection environment, etc., but is generally 5 to 30 mPa · s at 23 ° C. Preferably, the pressure is 5 to 15 mPa · s, and about 10 mPa · s is suitable for an inkjet recording apparatus.

3. Printing Method The inkjet printing method of the present invention can be carried out by ejecting a non-aqueous pigment ink onto a printing medium by an inkjet recording method, printing an image, and then printing the post-treatment liquid on the image. The printing method of the post-treatment liquid is not particularly limited as long as it can be printed on the non-aqueous pigment ink image, and the post-treatment liquid is applied to the printing surface of the printing medium by a method such as coating or printing. Specifically, it may be performed by uniformly coating the surface of the print medium using a brush, roller, bar coater, air knife coater, or the like, or inkjet printing, gravure The image may be printed by printing means such as printing or flexographic printing. For example, after printing an image by ejecting non-aqueous pigment ink onto a printing medium by an ink jet recording method, printing may be performed by continuously ejecting a post-treatment liquid on the image by the ink jet recording method. . In this case, the discharge of the non-aqueous pigment ink and the discharge of the post-treatment liquid may be continuously performed using the same ink jet printer. In the present invention, it is preferable that after the non-aqueous pigment ink is discharged onto the printing medium, the post-treatment liquid is discharged before the discharged non-aqueous pigment ink is completely dried.

  In the present invention, the printing medium is not particularly limited, and printing paper such as plain paper, coated paper and special paper, cloth, inorganic sheet, film, OHP sheet, and an adhesive layer on the back surface using these as a base material. An adhesive sheet or the like can be used. Among these, printing paper such as plain paper and coated paper can be preferably used.

  Plain paper is printing paper on which an ink receiving layer, a film layer, or the like is not formed. Examples of plain paper include high quality paper, medium quality paper, PPC paper, renewal paper, and recycled paper. As the coated paper, so-called coated printing paper or inkjet coated paper can be preferably used. Coated printing paper is printing paper conventionally used for letterpress printing, offset printing, gravure printing, etc., and uses a paint containing an inorganic pigment such as clay or calcium carbonate and a binder such as starch, It is a printing paper in which a coating layer is provided on the surface of paper or medium quality paper. Coated printing paper can be applied to fine coated paper, high-quality lightweight coated paper, medium-weight lightweight coated paper, high-quality coated paper, medium-quality coated paper, art paper, cast coated paper, etc., depending on the coating amount and coating method. being classified. Examples of the ink-jet coated paper include matte paper and photo glossy paper.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited only to this Example.

<Creation of non-aqueous pigment ink>
Dinomill KDL A type (Shinmaru Enterprises Co., Ltd.) in which pigment, water-insoluble organic solvent and pigment dispersant were mixed in the proportions shown in Table 1 and filled with zirconia beads (diameter 0.5 mm) at a filling rate of 85% Produced a non-aqueous pigment ink by dispersion under the conditions of a residence time of 15 minutes.

Examples 1-6, Comparative Examples 1-4
Dynomill KDL A type (Shinmaru Enterprises Co., Ltd.) in which silica, pigment dispersant and water-insoluble organic solvent are mixed in the proportions shown in Table 1 and filled with zirconia beads (diameter 0.5 mm) at a filling rate of 85% To obtain a dispersion liquid. And the emulsifier of the ratio shown in Table 1 was added to the said dispersion liquid, and the oil phase of the composition shown in Table 1 was obtained.
Moreover, water and water-soluble resin were mixed in the ratio shown in Table 1, and the water phase was obtained. Then, using a high-speed homogenizer “Viscotron” (trade name: manufactured by Microtech Nichion), the oil phase was added dropwise to the ratio shown in Table 1 while stirring at 8,000 rpm for 5 minutes. By stirring at 15,000 rpm for 5 minutes, a water-in-oil (W / O) emulsion was prepared and prepared as a post-treatment liquid.

  Then, the non-aqueous pigment ink and the post-treatment liquid shown in Table 1 were loaded into Orpheus X9050 (manufactured by Riso Kagaku Kogyo Co., Ltd.), and solid images were printed on the plain paper with the non-aqueous pigment ink. Then, the post-treatment liquid was overprinted on the solid image and printed. The scratch resistance and printing density of the obtained printed material were evaluated by the following methods. The results are shown in Table 1.

<Abrasion resistance>
The degree of soiling of the finger and paper when the surface of the solid image of the obtained printed material was rubbed with the finger was visually confirmed and evaluated according to the following criteria.
◯: There were no smudged fingers and paper.
Δ: Slightly smudged fingers and paper.
X: The rubbed finger and the paper were very dirty.

<Print density>
24 hours after printing, the OD values of the front and back surfaces of the solid image were measured using an optical densitometer (RD920, manufactured by Macbeth) and evaluated according to the following criteria.
Print density (Table OD)
○: 1.15 or more ×: 1.14 or less
Print density (back OD)
○: 0.20 or less ×: 0.21 or more

The detail of each component described in Table 1 is as follows.
-NEROX 600: Trade name of carbon black manufactured by Evonik Degussa Japan.
-ISOPAR G: Trade name of petroleum hydrocarbon solvent manufactured by TonenGeneral Sekiyu K.K.
Sols Pearl 19000: trade name of pigment dispersant (active ingredient ratio: 90 to 100%) manufactured by Nippon Lubrizol Co., Ltd.
AEROSIL R106: trade name of powder silica (average particle size: 250 ± 30 nm) manufactured by Nippon Aerosil Co., Ltd.
-Solsperse 13940: trade name of pigment dispersant (active ingredient ratio 30%) manufactured by Nippon Lubrizol Co., Ltd.
-NIKKOL Hexaglyn PR-15: The brand name of the surfactant by Nikko Chemicals.
Epomin SP-200: trade name of a water-soluble resin (polyethyleneimine having a number average molecular weight of 10,000) manufactured by Nippon Shokubai.
-Epomin SP-006: trade name of water-soluble resin (polyethyleneimine having a number average molecular weight of 600) manufactured by Nippon Shokubai.
Epomin SP-003: trade name of a water-soluble resin (polyethyleneimine having a number average molecular weight of 300) manufactured by Nippon Shokubai.
Epomin P-1000: trade name of a water-soluble resin manufactured by Nippon Shokubai (polyethyleneimine having a number average molecular weight of 70,000 and an active ingredient ratio of 30%).
-Polyethylene Glycol 600: Wako Pure Chemical Industries (average molecular weight 560-640).

  From the results of Table 1, in Examples 1 to 6 according to the printing method of the present invention, the print density (table OD) of the print image is high and the print density (back OD) is low (that is, there is little show-through). In addition, in the case of Comparative Examples 1 to 3 where the post-treatment liquid contains silica but does not contain a water-soluble resin having an amino group, the scratch resistance is inferior. In the case of Comparative Example 4 in which the treatment liquid contains a water-soluble resin having an amine group but no silica, it can be seen that the print density (table OD) of the printed image is inferior.

  The present invention can be widely used in the field of ink-jet printing because a non-aqueous pigment ink can be printed on a print medium by ink-jet printing and the post-treatment liquid can be easily printed by an ink-jet recording method or the like.

Claims (3)

  An inkjet printing method for printing an image with a non-aqueous pigment ink containing at least a pigment and a water-insoluble organic solvent by an inkjet recording method, and then printing a post-treatment liquid on the image, the post-treatment liquid Is an ink-jet printing method which is a water-in-oil (W / O) emulsion containing silica in an oil phase and a water-soluble resin having an amino group in an aqueous phase.   The printing method according to claim 1, wherein the water-soluble resin contained in the post-treatment liquid is polyethyleneimine.   The printing method according to claim 1 or 2, wherein the polyethyleneimine has an average molecular weight of 500 to 50,000.