Treatment liquid and ink set, image forming method, and image forming apparatus

Abstract

To provide a set of a process liquid and inks that can give a clear image with less color bleeding.SOLUTION: Provided is a set of a process liquid and inks, including a process liquid containing a flocculant, a non-white ink containing a coloring material other than white, and a white ink containing a white coloring material. When an aqueous solution containing the white ink 1 vol.% diluted with water and an aqueous solution containing calcium acetate 1 mass% are mixed with each other, a rate of initial increase in particle diameter is 30 nm / sec or greater after a lapse of 20 seconds from the start of mixing.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a treatment liquid and ink set, an image forming method, and an image forming apparatus. [Background technology]

[0002] In recent years, even in the fields of commercial and industrial printing, where analog printing such as offset printing and flexographic printing is mainstream, there has been a growing demand for inkjet printers as a digital printing method that can print a wide variety of designs in small quantities without the need for plates.

[0003] In commercial printing, the main printed items include pamphlets, catalogs, posters, manuals, etc. In industrial printing, the main printed items include labels, packaging, textiles, cardboard, etc. In particular, in the field of industrial printing, designs with a wide variety of small quantities are preferred and are used to promote products.

[0004] An example of such a small-volume, high-mix printing application is the packaging printing of food and daily necessities, which is printed on a non-absorbent recording medium such as plastic film. In such packaging printing applications, printed matter is often viewed at close range, so extremely high image quality is required.

[0005] Furthermore, in the field of industrial printing such as for flexible food packaging, reverse printing is used from the viewpoints of improving print quality, preventing abrasion and contamination of the printed surface, etc. In this reverse printing, white ink is printed on top of color ink (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a set of a treatment liquid and an ink that produces clear images with little bleeding between colors. [Means for solving the problem]

[0007] The treatment liquid and ink set of the present invention, which is a means for solving the above-mentioned problems, comprises a treatment liquid containing an aggregating agent, a non-white ink containing a colorant other than white, and a white ink containing a white colorant, and when a 1 volume % aqueous solution of the white ink diluted with water is mixed with a 1 mass % aqueous solution of calcium acetate, the initial particle size increase rate is 30 nm / sec or more up to 20 seconds after the start of mixing. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a set of treatment liquid and ink that produces clear images with little bleeding between colors. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic view showing an example of an image forming apparatus of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing an example of a chart used for image formation in the examples, in which a solid image of a non-white ink is included in a solid image of a white ink. DETAILED DESCRIPTION OF THE INVENTION

[0010] (treatment liquid and ink set) The treatment liquid and ink set of the present invention comprises a treatment liquid containing an aggregating agent, a non-white ink containing a colorant other than white, and a white ink containing a white colorant, and when a 1 volume % aqueous solution of the white ink diluted with water is mixed with a 1 mass % aqueous solution of calcium acetate, the initial particle size increase rate from the start of mixing to 20 seconds is 30 nm / sec or more.

[0011] Conventional technology has issues with printing processes such as reverse printing, in which the printed material is viewed from the back, such as bleeding occurring depending on the combination of white ink and color ink used, or when white ink is applied on top of color ink, the white ink does not wet and spread sufficiently over the color ink, resulting in a phenomenon known as "repellency."

[0012] In the present invention, when a 1% by volume aqueous solution of the white ink diluted with water is mixed with a 1% by mass aqueous solution of calcium acetate, the initial particle size increase rate from the start of mixing to 20 seconds is 30 nm / sec or more, thereby producing a clear image with little bleeding between colors. This is because the white ink reacts with the polyvalent metal salt, which is the aggregating agent in the treatment liquid, and agglomerates quickly, preventing the white ink from flowing on the non-permeable recording medium and allowing it to be fixed before bleeding between colors occurs.

[0013] <Initial particle size increase rate> When a 1% by volume aqueous solution of the white ink diluted with water is mixed with a 1% by mass aqueous solution of calcium acetate, the initial particle size increase rate from the start of mixing until 20 seconds has elapsed is 30 nm / sec or more, preferably 33 nm / sec or more, and from the viewpoint of storage stability, preferably 70 nm / sec or less. A 1% by volume aqueous solution of the white ink was prepared by adding 99 mL of water to 1 mL of the white ink. The initial particle size increase rate can be determined by first measuring the particle size of a 1% by volume aqueous solution of white ink diluted with water, and then measuring the particle size over time when mixing a 1% by volume aqueous solution of white ink with a 1% by mass aqueous solution of calcium acetate. Specifically, 4 mL of a 1% by volume aqueous solution of white ink is mixed with 0.5 mL of a 1% by mass aqueous solution of calcium acetate, and the initial particle size increase rate is determined from the start of mixing until 20 seconds have elapsed. The particle size is measured, for example, by the cumulant method using a particle size measurement system (ELSZ-1000S, manufactured by Otsuka Electronics Co., Ltd.). A 1% by volume aqueous solution of white ink and a 1% by mass aqueous solution of calcium acetate are mixed, and the particle size is measured every few seconds from the start of mixing using the cumulant method. The particle size data is plotted to form a straight line, and the initial particle size increase rate (nm / sec) can be calculated from the slope of the linear approximation from the start of mixing (0 seconds) until 20 seconds have elapsed.

[0014] The initial particle size increase rate of the white ink can be adjusted by adjusting the components contained in the white ink. For example, increasing the amount of dispersant contained in the pigment dispersion and resin dispersion improves reactivity with the calcium acetate mixed therein, thereby increasing the initial particle size increase rate. The initial particle size increase rate can also be adjusted by adjusting the type of dispersant. The initial particle size increase rate can be increased by using a dispersant containing many anionic functional groups, such as hydroxyl groups. Two or more types of dispersants may be used in combination, and by adjusting the blending ratio, a white ink with the desired initial particle size increase rate can be prepared. From the viewpoint of improving the initial particle size increase rate, the content of the dispersant is preferably from 5% by mass to 11% by mass, particularly preferably from 7% by mass to 11% by mass.

[0015] <White ink> The white ink contains water, a coloring material, an organic solvent, and a surfactant, and may further contain other components as required.

[0016] <<Organic solvents>> The organic solvent is not particularly limited, and any water-soluble organic solvent can be used, including, for example, polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.

[0017] Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, Examples of suitable glycerols include 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol. Examples of polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether. Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone. Examples of amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide. Examples of amines include monoethanolamine, diethanolamine, and triethylamine. Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol. Other organic solvents include, for example, propylene carbonate and ethylene carbonate. It is preferable to use an organic solvent having a boiling point of 250° C. or less, since it not only functions as a wetting agent but also provides good drying properties.

[0018] The content of the organic solvent in the white ink is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of the drying property and ejection reliability of the white ink, however, the content is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

[0019] <<Wed>> As the water, for example, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water can be used. The water content in the ink is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of the drying property and ejection reliability of the ink, however, it is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

[0020] <<Colorants>> The coloring material is not particularly limited as long as it is white, and pigments and dyes can be used. Examples of white pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, etc. In addition, resin hollow particles and inorganic hollow particles can also be used. The content of the coloring material in the white ink is preferably from 0.1% to 15% by mass, and more preferably from 1% to 10% by mass, from the viewpoints of improving image density, good fixability, and ejection stability.

[0021] Methods for dispersing a pigment to obtain a white ink include a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant. As a method for introducing a hydrophilic functional group into a pigment to make it a self-dispersible pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (e.g., carbon) to make it dispersible in water can be mentioned. One method for coating the surface of a pigment with a resin and dispersing it is to encapsulate the pigment in microcapsules to make it dispersible in water. This can be rephrased as a resin-coated pigment. In this case, it is not necessary for all of the pigments blended into the white ink to be coated with resin; uncoated or partially coated pigments may be dispersed in the white ink as long as the effects of the present invention are not impaired. Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a high molecular weight dispersant, such as a surfactant. As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the pigment. As the dispersant, RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used. The dispersants may be used alone or in combination of two or more.

[0022] -Pigment dispersion- White ink can be obtained by mixing a pigment with water, an organic solvent, or the like. Alternatively, white ink can be produced by mixing a pigment with other ingredients such as water and a dispersant to form a pigment dispersion, and then mixing the pigment with other ingredients such as water and an organic solvent. The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and optionally other components, and adjusting the particle size. Dispersion is preferably performed using a disperser. Although there are no particular restrictions on the particle size of the pigment in the pigment dispersion, the maximum frequency, calculated as the maximum number, is preferably 20 nm or more and 500 nm or less, and more preferably 20 nm or more and 150 nm or less, in order to improve the dispersion stability of the pigment and image quality such as ejection stability and image density. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.). The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of obtaining good ejection stability and increasing image density, the content is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 0.1% by mass or more and 30% by mass or less. It is preferable to filter out coarse particles from the pigment dispersion using a filter, a centrifugal separator or the like, and degas the dispersion, if necessary.

[0023] <<Surfactants>> The white ink preferably contains a silicone surfactant as a surfactant. The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include BYK-333, BYK-378, BYK-307, BYK-3450 (all manufactured by BYK), KF-351 (manufactured by Shin-Etsu Chemical Co., Ltd.), wet-260, wet-270, wet-280 (manufactured by Evonik), SAG503A, SAG016, SAG008, PD-502 (manufactured by Nissin Chemical Industry Co., Ltd.), and the like.

[0024] The white ink may contain other surfactants as listed below. Examples of other surfactants include fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants. As fluorosurfactants, for example, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain are particularly preferred due to their low foaming properties. Examples of the perfluoroalkyl sulfonic acid compounds include perfluoroalkyl sulfonic acids and perfluoroalkyl sulfonate salts. Examples of the perfluoroalkyl carboxylic acid compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylate salts. Examples of the polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain. Counterions of the salts in these fluorosurfactants include Li, Na, K, NH, NHCHCHOH, NH(CHCHOH), NH(CHCHOH), and the like.

[0025] Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine. Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol. Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzenesulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates. The other surfactants may be used alone or in combination of two or more.

[0026] <<Resin>> The type of resin contained in the white ink is not particularly limited and can be appropriately selected depending on the purpose. Examples include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic-styrene resin, and acrylic-silicone resin. Resin particles made of these resins may also be used. The resin particles are dispersed in water as a dispersion medium to form a resin emulsion, which can be mixed with materials such as coloring materials and organic solvents to obtain an ink. The resin particles may be appropriately synthesized or commercially available. These may be used alone or in combination of two or more types of resin particles.

[0027] The volume average particle size of the resin particles is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of obtaining good fixing properties and high image hardness, the volume average particle size is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less. The volume average particle size can be measured, for example, using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0028] The resin content is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of fixability and storage stability of the white ink, the resin content is preferably 1% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, of the total amount of the white ink.

[0029] The resin particles may be appropriately synthesized or may be commercially available. Examples of commercially available resin particles include Microgel E-1002 and E-5002 (styrene-acrylic resin particles, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin particles, manufactured by DIC Corporation), Boncoat 5454 (styrene-acrylic resin particles, manufactured by DIC Corporation), SAE-1014 (styrene-acrylic resin particles, manufactured by Zeon Corporation), Saivinol SK-200 (acrylic resin particles, manufactured by Saiden Chemical Industry Co., Ltd.), Primal AC-22 and AC-61 (acrylic resin particles, manufactured by Rohm and Haas), Nanocryl SBCX-2821 and 3689 (acrylic-silicone resin particles, manufactured by Toyo Ink Co., Ltd.), and #3070 (methyl methacrylate polymer resin particles, manufactured by Mikuni Shikiso Co., Ltd.). These may be used alone or in combination of two or more.

[0030] <<Other ingredients>> The white ink may further contain other components such as an antifoaming agent, an antiseptic / fungal agent, and an antirust agent, if necessary.

[0031] -Antifoaming agent- The antifoaming agent is not particularly limited, and examples thereof include silicone-based antifoaming agents, polyether-based antifoaming agents, and fatty acid ester-based antifoaming agents. These may be used alone or in combination of two or more. Among these, silicone-based antifoaming agents are preferred because of their excellent foam-breaking effect.

[0032] -Preservative and fungicide- The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

[0033] -Rust inhibitor- The rust inhibitor is not particularly limited, and examples thereof include acid sulfites and sodium thiosulfate.

[0034] <Physical properties of white ink> The physical properties of the white ink are not particularly limited and can be selected appropriately depending on the purpose. For example, it is preferable that the viscosity, pH, etc. are within the following ranges. The viscosity of the white ink at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, and more preferably 5 mPa·s or more and 25 mPa·s or less, in order to improve print density and character quality and obtain good ejection properties. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L, manufactured by Toki Sangyo Co., Ltd.). Measurement conditions include 25°C, a standard cone rotor (1°34' x R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes. The pH of the white ink is preferably 7 to 12, and more preferably 8 to 11, from the viewpoint of preventing corrosion of metal members that come into contact with the ink.

[0035] There are also no particular restrictions on the surface tension of the white ink. When a pattern is printed with a non-white ink and then a white ink is printed so as to overlap the non-white ink, the surface tension of the previously printed non-white ink can easily cause bleeding or repelling of the subsequently printed white ink.

[0036] <Non-white ink> The non-white ink contains water, a coloring material, an organic solvent, and a surfactant, and may further contain other components as required.

[0037] <<Surfactants>> The non-white ink preferably contains an acetylene glycol surfactant as a surfactant. The acetylene glycol surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include Surfynol DF110D, Surfynol 104E, Surfynol 82, Surfynol 420, Surfynol 440, Surfynol 465, Surfynol 485, Surfynol PSA-336, Surfynol E1004, and Surfynol EXP4200 (all manufactured by Nissin Chemical Industry Co., Ltd.).

[0038] In the present invention, the non-white ink contains an acetylene glycol surfactant, and the white ink contains a silicone surfactant, which improves the wettability with the previously printed non-white ink, resulting in a clear image with little repelling.

[0039] The non-white ink may contain other surfactants in addition to the acetylene glycol surfactant. Examples of other surfactants include silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants. Silicone surfactants are not particularly limited and can be appropriately selected according to purpose.Among these, those that do not decompose even at high pH are preferred, for example, side chain modified polydimethylsiloxane, both end modified polydimethylsiloxane, one end modified polydimethylsiloxane, side chain both end modified polydimethylsiloxane, etc., and those having polyoxyethylene group or polyoxyethylene polyoxypropylene group as modified group are particularly preferred because they exhibit good properties as aqueous surfactants.In addition, polyether modified silicone surfactants can also be used as the silicone surfactant, for example, compounds in which polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane, etc.

[0040] As fluorosurfactants, for example, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain are particularly preferred due to their low foaming properties. Examples of the perfluoroalkyl sulfonic acid compounds include perfluoroalkyl sulfonic acids and perfluoroalkyl sulfonate salts. Examples of the perfluoroalkyl carboxylic acid compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylate salts. Examples of the polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain. Counterions of the salts in these fluorosurfactants include Li, Na, K, NH, NHCHCHOH, NH(CHCHOH), NH(CHCHOH), and the like.

[0041] Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine. Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol. Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzenesulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates. The other surfactants may be used alone or in combination of two or more.

[0042] -Coloring materials- The coloring material in the non-white ink is not particularly limited, and pigments and dyes can be used. The pigment may be an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more. Mixed crystals may also be used as the pigment. Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments. As inorganic pigments, in addition to barium yellow, cadmium red, and chrome yellow, carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used. Examples of organic pigments that can be used include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments), dye chelates (e.g., basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, and aniline black. Of these pigments, those with good affinity for the solvent are preferably used. Specific examples of pigments for black include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (CI Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (CI Pigment Black 1).

[0043] In addition, for color, CI Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, CI Pigment Orange Range 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 ( Bengara), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, CI Pigment Examples include Rhodamine Lake 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38, CI Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63, and CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36.

[0044] The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone, or two or more types may be used in combination. Dyes include, for example, CI Acid Yellow 17, 23, 42, 44, 79, 142, CI Acid Red 52, 80, 82, 249, 254, 289, CI Acid Blue 9, 45, 249, CI Acid Black 1, 2, 24, 94, CI Food Black 1, 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 1 73, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Directed Black 19, 38, 51, 71, 154, 168, 171, 195, CI Reactive Red 14, 32, 55, 79, 249, CI Reactive Black 3, 4, 35, etc.

[0045] The content of the coloring material in the non-white ink is preferably from 0.1% to 15% by mass, and more preferably from 1% to 10% by mass, from the viewpoints of improving image density, good fixability, and ejection stability.

[0046] The water, organic solvent, resin, and other components in the non-white ink may be the same as the water, organic solvent, resin, and other components in the white ink.

[0047] The physical properties of the non-white ink are not particularly limited and can be selected appropriately depending on the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are within the following ranges. The viscosity of the non-white ink at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, and more preferably 5 mPa·s or more and 25 mPa·s or less, in order to improve print density and character quality and obtain good jetting properties. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L, manufactured by Toki Sangyo Co., Ltd.). Measurement conditions include 25°C, a standard cone rotor (1°34' x R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.

[0048] In order to ensure that the white ink can be suitably leveled and to prevent inter-color bleeding or repellency due to the wetting and spreading of the white ink even when no drying step is included between the printing of the non-white ink that is printed first and the printing of the white ink that is printed later, the surface tension of the non-white ink that is printed first is preferably 20 mN / m to 45 mN / m at 25°C, more preferably 30 mN / m to 40 mN / m, and even more preferably 35 mN / m to 40 mN / m.

[0049] The dynamic surface tension of the non-white ink at a surface life of 15 msec according to the maximum bubble pressure method is preferably 28 mN / m or more and 43 mN / m or less. The pH of the non-white ink is preferably 7 to 12, and more preferably 8 to 11, from the viewpoint of preventing corrosion of metal members that come into contact with the ink.

[0050] <Processing liquid> The treatment liquid contains water, a flocculant, an organic solvent, and a surfactant, and may further contain other components as required.

[0051] <<Flocculant>> The flocculant is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include water-soluble cationic polymers, acids, polyvalent metal salts, etc. Among these, polyvalent metal salts are preferred.

[0052] -Polyvalent metal salts- The polyvalent metal salt quickly aggregates the pigment in the ink after it has landed on the ink, suppressing color bleeding and improving color development. The polyvalent metal is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include titanium compounds, chromium compounds, copper compounds, cobalt compounds, strontium compounds, barium compounds, iron compounds, aluminum compounds, calcium compounds, and magnesium compounds. Among these polyvalent metal compounds, one or more selected from the group consisting of calcium compounds, magnesium compounds, nickel compounds, and aluminum compounds are preferred, as they can effectively aggregate the pigment in the ink, and divalent metal salts of calcium compounds, magnesium compounds, and the like are more preferred. When the treatment liquid contains a divalent metal salt as a flocculant, the treatment liquid is stable without precipitation of the flocculant, and the aggregation reaction with the non-white ink and the white ink proceeds quickly, making it suitable for preventing bleeding.

[0053] Examples of the divalent metal salt include calcium carbonate, calcium nitrate, calcium chloride, calcium acetate, calcium sulfate, magnesium chloride, magnesium acetate, magnesium sulfate, barium sulfate, zinc sulfide, and zinc carbonate.

[0054] The content of the aggregating agent is preferably 4% by mass or more, more preferably 6% by mass or more, based on the total amount of the treatment liquid. When the content of the aggregating agent is 4% by mass or more, the reactivity of the treatment liquid with the ink is further increased, making it possible to prevent bleeding. From the viewpoint of storage stability, the upper limit is preferably 9% by mass or less.

[0055] The water, organic solvent, surfactant, and other components contained in the treatment liquid can be the same as the water, organic solvent, surfactant, and other components in the white ink and non-white ink.

[0056] <Recording Media> The non-permeable recording medium used in the present invention is a recording medium having a surface with low water permeability and low absorbency, and includes materials that have many cavities inside but are not open to the outside. More quantitatively, in the Bristow method, 1 / 2 Water absorption up to 10mL / m 2 The recording medium is as follows: As the non-permeable recording medium, for example, vinyl chloride resin film, polyethylene terephthalate (PET) film, polypropylene, polyethylene, polycarbonate film, nylon film, etc. can be suitably used.

[0057] Examples of the polypropylene film include P-2002, P-2161, and P-4166 manufactured by Toyobo Co., Ltd., PA-20, PA-30, and PA-20W manufactured by Suntox Corporation, and FOA, FOS, and FOR manufactured by Futamura Chemical Co., Ltd. Examples of the polyethylene terephthalate film include E-5100 and E-5102 manufactured by Toyobo Co., Ltd., P60 and P375 manufactured by Toray Industries, Inc., and G2, G2P2, K, and SL manufactured by Teijin DuPont Films Limited. Examples of the nylon film include Harden Film N-1100, N-1102, and N-1200 manufactured by Toyobo Co., Ltd., and ON, NX, MS, and NK manufactured by Unitika Ltd.

[0058] (Image forming method and image forming apparatus) The image forming method of the present invention comprises a treatment liquid application step of applying the treatment liquid in the treatment liquid and ink set of the present invention to a non-permeable recording medium, a non-white ink application step of applying the non-white ink in the treatment liquid and ink set of the present invention, and a white ink application step of applying the white ink in the treatment liquid and ink set of the present invention, and may further comprise other steps as necessary.

[0059] The image forming apparatus of the present invention comprises a treatment liquid storage means for storing the treatment liquid in the treatment liquid and ink set of the present invention, an ink storage means for storing the white ink and non-white ink in the treatment liquid and ink set of the present invention, a treatment liquid application means for applying the treatment liquid to a non-permeable recording medium, a non-white ink application means for applying the non-white ink, and a white ink application means for applying the white ink, and may further comprise other means as necessary. There is no lower limit to the total amount of non-white ink and white ink applied, but to prevent bleeding, the lower the ink amount, the better, so the upper limit is 40 μg / inch 2 Less than 20 μg / inch is preferred 2 Less than 10 μg / inch is more preferable. 2 The following is even more preferred: The total amount of non-white ink and white ink applied is 20 μg / inch 2 When the image forming method is as follows, all of the ink on the substrate reacts with the treatment liquid and aggregates, so the ink quickly loses its fluidity and bleeding is unlikely to occur. 2 It is preferable that this is equal to or greater than this. There are no particular limitations on the breakdown of the amounts of non-white ink and white ink applied, and any number of inks may be used. For example, one type of non-white ink may be used, or two or more types may be used in combination.

[0060] When the image forming method includes a non-white ink drying step of drying the non-white ink between the non-white ink applying step and the white ink applying step, the fluidity of the previously applied ink is lost by drying, and new ink can be applied thereafter, preventing the inks from mixing on the non-permeable recording medium and resulting in a clear image with less bleeding. The drying means is not particularly limited as long as it can dry the printed surface and back surface of the recording medium, and can be appropriately selected depending on the purpose. Examples include a hot air heater, an infrared heater, a heating roller, and a hot plate.

[0061] The image forming method preferably includes a surface modification step of modifying the surface of the non-permeable recording medium, which is preferably performed before applying the ink of the treatment liquid and ink set to the non-permeable recording medium. By modifying the surface of the non-permeable recording medium, the wettability of the ink to the non-permeable recording medium is improved, and an image that is not repellent can be obtained, which is preferable. Examples of surface treatments include corona treatment, atmospheric pressure plasma treatment, flame treatment, and ultraviolet irradiation treatment. Among these, the surface modification of the recording surface is preferably a corona treatment step in which corona treatment is performed on the recording surface. Corona treatment is preferably used because it has superior corona discharge output stability compared to atmospheric pressure plasma treatment, flame treatment, and ultraviolet irradiation treatment, and can perform surface treatment uniformly on the recording surface.

[0062] <Image forming apparatus and image forming method> The ink and treatment liquid set of the present invention can be suitably used in various recording devices using the inkjet recording method, such as printers, facsimile machines, copying machines, printer / fax / copier combination machines, and three-dimensional modeling devices. In this invention, the image forming apparatus and image forming method refer to an apparatus capable of ejecting ink, various treatment liquids, etc. onto a recording medium, and a method of recording using such an apparatus. The recording medium refers to a medium to which ink or various treatment liquids can be applied, even temporarily. Furthermore, this recording apparatus also includes desktop image forming apparatuses and wide-format image forming apparatuses capable of printing on A0-size recording media, such as continuous feed printers that can use continuous paper wound into a roll as the recording medium. FIG. 1 shows an example of an image forming apparatus. In the image forming method of the present invention, the step of applying the ink and the step of applying the pretreatment liquid may be carried out by the same printing machine, or may be carried out by different printing machines.

[0063] The image forming apparatus 100 in FIG. 1 includes a pretreatment liquid applying unit 110, an ink applying unit 120, a posttreatment liquid applying unit 130, a drying unit 140, and a conveying unit 150. The pretreatment liquid applying unit 110 applies the pretreatment liquid to a recording medium M. The pre-treatment liquid application unit 110, the post-treatment liquid application unit 130, the drying unit 140, and the transport unit 150 may be omitted.

[0064] The method for applying the pretreatment liquid is not particularly limited, but examples thereof include an inkjet method, a roller coating method, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, a U-comma coating method, an AKKU coating method, a smoothing coating method, a microgravure coating method, a reverse roll coating method, a four-roll or five-roll coating method, a dip coating method, a curtain coating method, a slide coating method, and a die coating method. The pretreatment liquid application unit 110 may be omitted because the pretreatment liquid may be applied manually to the recording medium in advance by a bar coating method or the like and then printed using the image forming apparatus.

[0065] The recording medium M used for recording is not particularly limited, but may be, for example, plain paper, glossy paper, Examples include special paper, cardboard, cloth, film, OHP sheets, and general-purpose printing paper.

[0066] The ink application unit 120 applies ink-jet ink to the surface of the recording medium M on which the pretreatment liquid has been applied. Assign a check. As the ink applying unit 120, for example, a known inkjet head can be used. The ink application unit 120 may be a head that ejects ink of any color, and for example, a head that ejects ink of the colors Y (yellow), M (magenta), C (cyan), K (black), and W (white) may be provided as needed.

[0067] The post-treatment liquid application unit 130 may be configured to apply the post-treatment liquid to the area on the surface of the recording medium M to which the inkjet ink has been applied, and may be configured using a spray, a roller, or the like in addition to an inkjet head. The post-treatment liquid application unit 130 may be omitted.

[0068] The method for applying the post-treatment liquid is not particularly limited, but examples thereof include an inkjet method, a roller coating method, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, a U-comma coating method, an AKKU coating method, a smoothing coating method, a microgravure coating method, a reverse roll coating method, a four-roll or five-roll coating method, a dip coating method, a curtain coating method, a slide coating method, and a die coating method.

[0069] The drying section 140 dries the recording medium M to which the post-treatment liquid has been applied with hot air. If there is no post-treatment liquid application section, the drying section 140 may be omitted. The drying section 140 may use infrared rays, microwaves, a roll heater, or the like instead of hot air to heat and dry the recording medium M to which the post-treatment liquid has been applied, or the drying section 140 may not be operated and the recording medium M to which the post-treatment liquid has been applied may be allowed to dry naturally.

[0070] The conveying section 150 conveys the recording medium M. The conveying unit 150 is not particularly limited as long as it can convey the recording medium M. However, examples of such components include a conveyor belt and a platen.

[0071] The image forming apparatus 100 may further include a fixing unit that heats and fixes the image formed on the recording medium M. The fixing unit is not particularly limited, but may include a fixing roller or the like.

[0072] When a desktop printer is used as an image forming apparatus, one embodiment of the pre-treatment liquid application unit and the post-treatment liquid application unit is to add a liquid storage unit containing the pre-treatment liquid or the post-treatment liquid and a liquid ejection head, and eject the pre-treatment liquid or the post-treatment liquid by an inkjet recording method, as in the case of inks such as black (K), cyan (C), magenta (M), yellow (Y), and white (W).

[0073] In addition, in the present invention, the terms image formation, recording, printing, printing, etc. are all synonymous. Recording medium, media, and printed material are all synonymous terms. [Example]

[0074] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0075] (Pigment Dispersion Liquid Preparation Example 1) <Preparation of black pigment dispersion> A mixture of the following formulation was premixed and then circulated and dispersed for 7 hours in a disk-type bead mill (KDL model, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls with a diameter of 0.3 mm) to obtain a black pigment dispersion (pigment concentration: 15% by mass). [Black pigment dispersion formulation] Carbon black pigment (product name: Monarch 800, manufactured by Cabot Corporation): 15 parts by mass Acrylic polymer dispersant (product name: Disperbyk-2010, manufactured by BYK Japan): 5 parts by mass Ion-exchanged water: 80 parts by weight

[0076] (Pigment Dispersion Liquid Preparation Example 2) <Preparation of cyan pigment dispersion> A cyan pigment dispersion (pigment solids concentration: 15% by mass) was obtained in the same manner as in Pigment Dispersion Preparation Example 1, except that the carbon black pigment in Pigment Dispersion Preparation Example 1 was changed to Pigment Blue 15:3.

[0077] (Pigment Dispersion Liquid Preparation Example 3) <Preparation of magenta pigment dispersion> A magenta pigment dispersion (pigment solids concentration: 15% by mass) was obtained in the same manner as in Pigment Dispersion Preparation Example 1, except that the carbon black pigment in Pigment Dispersion Preparation Example 1 was changed to Pigment Red 269.

[0078] (Pigment Dispersion Liquid Preparation Example 4) <Preparation of Yellow Pigment Dispersion> A yellow pigment dispersion (pigment solids concentration: 15% by mass) was obtained in the same manner as in Pigment Dispersion Preparation Example 1, except that the carbon black pigment in Pigment Dispersion Preparation Example 1 was changed to Pigment Yellow 74.

[0079] (Pigment Dispersion Liquid Preparation Example 5) <Preparation of White Pigment Dispersion Liquid 1> 25 parts by mass of titanium oxide (trade name: STR-100W, manufactured by Sakai Chemical Industry Co., Ltd.), 5 parts by mass of a pigment dispersant (trade name: TEGO Dispers 651, manufactured by Evonik), and 70 parts by mass of water were mixed, and the mixture was dispersed with zirconia beads having a diameter of 0.3 mm at a filling rate of 60% and at 8 m / s for 5 minutes using a bead mill (trade name: Research Lab, manufactured by Shinmaru Enterprises Co., Ltd.) to obtain white pigment dispersion 1 (pigment solids concentration: 25% by mass).

[0080] (Pigment Dispersion Liquid Preparation Example 6) <Preparation of White Pigment Dispersion Liquid 2> White pigment dispersion 2 (pigment solids concentration: 25% by mass) was obtained in the same manner as in Pigment Dispersion Preparation Example 5, except that the pigment dispersant was changed to 7 parts by mass and the water was changed to 68 parts by mass.

[0081] (Pigment Dispersion Liquid Preparation Example 7) <Preparation of White Pigment Dispersion 3> White pigment dispersion 3 (pigment solids concentration: 25% by mass) was obtained in the same manner as in Pigment Dispersion Preparation Example 5, except that the pigment dispersant was changed to 3 parts by mass and the water was changed to 72 parts by mass.

[0082] (Pigment Dispersion Liquid Preparation Example 8) <Preparation of White Pigment Dispersion Liquid 4> White pigment dispersion 4 (pigment solids concentration: 25% by mass) was obtained in the same manner as in Pigment Dispersion Preparation Example 5, except that the pigment dispersant was changed to 9 parts by mass and the water was changed to 66 parts by mass.

[0083] (Pigment Dispersion Liquid Preparation Example 9) <Preparation of White Pigment Dispersion 5> White pigment dispersion 5 (pigment solids concentration: 25% by mass) was obtained in the same manner as in Pigment Dispersion Preparation Example 5, except that the pigment dispersant was changed to 11 parts by mass and the water was changed to 64 parts by mass.

[0084] (Resin Dispersion Production Example 1) -Production of Resin Dispersion 1- A mixture consisting of 65 parts by mass of methyl methacrylate, 31 parts by mass of 2-ethylhexyl acrylate, 2 parts by mass of methacrylic acid, 2 parts by mass of Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 52 parts by mass of ion-exchanged water was emulsified using a homomixer to obtain a uniform milky white emulsion. A 250 mL flask equipped with a stirrer, thermometer, nitrogen gas inlet tube, and reflux condenser was charged with 89 parts by mass of ion-exchanged water and heated to 70°C while introducing nitrogen. Next, 0.8 parts by mass of a 10% by mass aqueous solution of Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 2.6 parts by mass of a 5% by mass aqueous solution of ammonium persulfate were added, followed by continuous dropwise addition of a pre-prepared emulsion over 2.5 hours. Furthermore, 0.6 parts by mass of a 5% by mass aqueous solution of ammonium persulfate was added every hour for 3 hours from the start of the dropwise addition. After the dropwise addition was completed, the mixture was aged at 70°C for 2 hours, cooled, and the pH was adjusted to 7-8 with 28% by mass aqueous ammonia, yielding Resin Dispersion 1. The glass transition temperature (Tg) of the obtained resin was 53° C. Here, the glass transition temperature (Tg) was measured using a differential scanning calorimetry (DSC) (Thermo plus EVO2 / DSC, manufactured by Rigaku Corporation).

[0085] (Resin Dispersion Production Example 2) -Production of Resin Dispersion 2- Resin dispersion 2 was obtained in the same manner as in Resin dispersion production example 1, except that the amount of methyl methacrylate was 69 parts by mass and the amount of 2-ethylhexyl acrylate was 27 parts by mass. The glass transition temperature (Tg) of the obtained resin, measured in the same manner as in Resin dispersion production example 1, was 62°C.

[0086] (Resin Dispersion Production Example 3) -Production of Resin Dispersion 3- Resin dispersion 3 was obtained in the same manner as in Resin dispersion production example 1, except that the amount of methyl methacrylate was changed to 77 parts by mass and the amount of 2-ethylhexyl acrylate was changed to 19 parts by mass. The glass transition temperature (Tg) of the obtained resin, measured in the same manner as in Resin dispersion production example 1, was 85°C.

[0087] (Resin Dispersion Production Example 4) <Preparation of Urethane Resin Emulsion A> A reaction flask was charged with 1 mole of 1,6-hexanediol, 1.4 moles of dicyclohexylmethane diisocyanate, 0.1 mole of a diisocyanate compound obtained by reacting 1 mole of isocyanurate trimer of 1,6-hexamethylene diisocyanate with 1 / 3 mole of polyethylene glycol monomethyl ether having a molecular weight of 1,000, and 15 mass % of the total mass of N-methyl-2-pyrrolidone, and the mixture was reacted at 90°C for 2 hours under a nitrogen stream to obtain a prepolymer. To 600 g of water containing 0.2 g of a silicone antifoaming agent (SE-21, manufactured by Wacker Silicone) dissolved therein, 450 g of the prepolymer obtained above with a solid content of 85% by mass was added dropwise over 15 minutes. After stirring at 25°C for 10 minutes, a compound represented by the following structural formula (A), ethylenediamine, and adipic acid hydrazide were added dropwise to obtain polyurethane resin emulsion A.

[0088] [ka]

[0089] (Non-white ink preparation example 1) -Preparation of non-white ink 1- Non-white ink 1 was prepared by mixing and stirring the following non-white ink formulation and filtering it through a polypropylene filter with an average pore size of 0.8 μm. [Non-white ink formula] Black pigment dispersion: 20 parts by weight Surfynol 420 (manufactured by Nissin Chemical Industry Co., Ltd.): 0.5 parts by mass 1,2-propanediol: 15 parts by mass Ethylene glycol monobutyl ether: 10 parts by mass Proxel LV (Avecia, preservative): 0.1 parts by weight 1:10 parts by mass of the resin dispersion Ion-exchanged water: remaining amount (total: 100 parts by mass)

[0090] (Non-white ink preparation examples 2 to 6) -Preparation of non-white inks 2 to 6- Non-white inks 2 to 6 were prepared in the same manner as in Non-white ink preparation example 1, except that the non-white ink formulation in Non-white ink preparation example 1 was changed to that shown in Table 1. The numerical values ​​for the resin dispersion in Table 1 represent the resin content converted into solid content.

[0091] Next, the static surface tension of the obtained non-white ink was measured as follows, and the results are shown in Table 1.

[0092] <Static surface tension measurement> The static surface tension of the non-white ink was measured at 25°C using an automatic surface tensiometer (DY-300, manufactured by Kyowa Interface Science Co., Ltd.) More specifically, the non-white ink was poured into a 30 mm diameter petri dish, allowed to stand for 5 minutes, and then measured by the Wilhelmy method using a platinum plate with the automatic surface tensiometer DY-300.

[0093] [Table 1]

[0094] The details of each component in Table 1 are as follows: -Surfactants- Surfynol 420 (acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) Surfynol PSA-336 (acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) Surfynol 440 (acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) Surfynol 465 (acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) BYK-333 (silicone surfactant, manufactured by BYK) FS-300 (fluorosurfactant, manufactured by DuPont)

[0095] (White ink preparation example 1) -Preparation of White Ink 1- White ink 1 was prepared by mixing and stirring the following white ink formulation and filtering it through a polypropylene filter with an average pore size of 0.8 μm. [White ink formula] ·White pigment dispersion 2: 48 parts by mass BYK-333 (silicone surfactant, manufactured by BYK): 0.5 parts by weight 1,2-propanediol: 15 parts by mass Ethylene glycol monobutyl ether: 10 parts by mass Proxel LV (Avecia, preservative): 0.1 parts by weight 1:10 parts by mass of the resin dispersion Ion-exchanged water: remaining amount (total: 100 parts by mass)

[0096] (White ink preparation examples 2 to 11) -Preparation of White Inks 2 to 11- White inks 2 to 11 were prepared in the same manner as in White Ink Preparation Example 1, except that the white ink formulations in White Ink Preparation Example 1 were changed to those shown in Tables 2-1 and 2-2. The numerical values ​​for the resin dispersions in Tables 2-1 and 2-2 represent the resin content converted into solid content.

[0097] Next, the initial particle size increase rate of the obtained white ink was measured as follows, and the results are shown in Tables 2-1 and 2-2.

[0098] <Initial particle size increase rate> 4 mL of a 1% by volume aqueous solution of white ink was mixed with 0.5 mL of a 1% by mass aqueous solution of calcium acetate, and the initial particle size increase rate was determined from the start of mixing until 20 seconds after the start of mixing. The particle size was measured using the cumulant method with a particle size measurement system (Otsuka Electronics Co., Ltd., ELSZ-1000S). The 1% by volume aqueous solution of white ink and the 1% by mass aqueous solution of calcium acetate were mixed, and the particle size was measured every few seconds after the start of mixing using the cumulant method. The particle size data was plotted to form a straight line, and the initial particle size increase rate (nm / sec) was calculated from the slope of the linear approximation from the start of mixing (0 seconds) to 20 seconds after the start of mixing.

[0099] [Table 2-1]

[0100] [Table 2-2]

[0101] The details of each component in Tables 2-1 and 2-2 are as follows: -Surfactants- BYK-333 (silicone surfactant, manufactured by BYK) BYK-3450 (silicone surfactant, manufactured by BYK) wet-260 (silicone surfactant, manufactured by Evonik) wet-270 (silicone surfactant, manufactured by Evonik) wet-280 (silicone surfactant, manufactured by Evonik) SAG503A (silicone surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) FS-300 (fluorosurfactant, manufactured by DuPont) Surfynol 420 (acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.)

[0102] (Processing Solution Preparation Example 1) -Preparation of Processing Solution 1- Treatment liquid 1 was prepared according to the following composition, mixed and stirred, and filtered through a filter with an average pore size of 5 μm (Minisart, manufactured by Sartorius). [Processing solution formulation] 1,2-propanediol: 15 parts by mass Ethylene glycol monobutyl ether: 13 parts by mass Emulgen LS-106 (Kao Corporation, polyoxyalkyl ether surfactant): 0.5 parts by mass Magnesium sulfate: 6 parts by weight Proxel LV (Avecia, preservative): 0.1 parts by weight Ion-exchanged water: remaining amount (total: 100 parts by mass)

[0103] (Processing Solution Preparation Examples 2 to 8) -Preparation of Treatment Solutions 2 to 8- Treatment liquids 2 to 8 were prepared in the same manner as in Treatment liquid Preparation Example 1, except that the treatment liquid formulation was changed to that shown in Table 3.

[0104] [Table 3]

[0105] The details of each component in Table 3 are as follows: -Surfactants- Emulgen LS-106 (polyoxyalkyl ether surfactant, manufactured by Kao Corporation) BYK-333 (silicone surfactant, manufactured by BYK) BYK-3450 (silicone surfactant, manufactured by BYK) wet-270 (silicone surfactant, manufactured by Evonik) wet-280 (silicone surfactant, manufactured by Evonik) SAG503A (silicone surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) SAG016 (silicone surfactant, manufactured by Nissin Chemical Industry Co., Ltd.)

[0106] (Examples 1 to 21 and Comparative Examples 1 and 2) For the combinations of white ink, non-white ink, and treatment liquid shown in Tables 4-1 to 4-5, the driving voltage of the piezoelectric element was varied and an image forming apparatus (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) was adjusted so that the ejection amounts of the white ink and non-white ink were uniform under environmental conditions adjusted to 23°C ± 0.5°C and 50 ± 5% RH. The treatment liquid was applied to OPP (Toyobo Co., Ltd., Pylen P2102) using a bar coater No. 1 at a rate of 1.5 g / m 2 After coating so that the OPP was coated, it was dried at 80°C for 2 minutes, and a chart (see Figure 2) was set up so that the white ink and non-white ink were included in the white ink solid image on the dried OPP, and printing was performed using an image forming device. The total amount of white ink and non-white ink applied is shown in Tables 4-1 to 4-5. The OPP (Pylen P2102, manufactured by Toyobo Co., Ltd.) was used after being cut to an appropriate size. The white ink and non-white ink were ejected by ejecting the non-white ink first, followed by the white ink so that a boundary was formed between the non-white ink and the white ink. When an ink drying step was performed between the non-white ink application step and the white ink application step, a drying step of 2 minutes at 80°C was performed between the non-white ink application step and the white ink application step.

[0107] Next, various properties were evaluated as follows, and the results are shown in Tables 4-1 to 4-5.

[0108] <Bleeding evaluation> The solid image formed as described above was visually observed to evaluate the degree of bleeding based on the appearance of the non-white ink solid image that should have been covered with white ink, and the bleeding evaluation was carried out according to the following criteria, with C or higher being considered acceptable. [Evaluation criteria] A: No bleeding at all A-: There is bleeding that is not noticeable unless you look closely at the overlapping area of ​​non-white ink and white ink. B: Slight bleeding is visible to the eye at the edges of solid images of non-white ink. C: Slight bleeding is visible on the edges of solid images of non-white ink. D: The edges of a solid image with non-white ink are significantly blurred. E: Non-white ink and white ink are bleeding overall

[0109] <Playability evaluation> The solid image formed as described above was visually observed to evaluate the degree of repellency based on the appearance of the non-white ink solid image that should have been covered with white ink, and repellency was evaluated according to the following criteria. A grade of C or higher is considered acceptable. [Evaluation criteria] A: There is no exposure of the non-white ink solid image and the white ink solid image is uniform. B: No exposure of non-white ink solid images, but slight unevenness in white ink solid images C: No exposure of non-white ink solid image, but unevenness in white ink solid image D: Non-white ink solid image is exposed

[0110] <Stability of processing solution> A processing solution was prepared and stored at room temperature (25°C) for one week, after which the appearance of the processing solution was visually observed and the stability of the processing solution was evaluated according to the following criteria, with B or higher being within the acceptable range. [Evaluation criteria] A: After one week, there is no precipitation of metal salts and the entire solution is uniformly transparent. B: Immediately after preparation, the entire treatment solution is uniformly transparent, but after storing it for one week, the solution becomes cloudy and metal salts precipitate. C: The treatment solution is not uniform immediately after preparation, and turbidity and undissolved metal salts are visible.

[0111] [Table 4-1]

[0112] [Table 4-2]

[0113] [Table 4-3]

[0114] [Table 4-4]

[0115] [Table 4-5]

[0116] The present invention includes, for example, the following aspects. <1> a treatment liquid containing a flocculant; a non-white ink containing a color material other than white; a white ink containing a white colorant; and This is a set of treatment liquid and ink, characterized in that when a 1 volume % aqueous solution of the white ink diluted with water is mixed with a 1 mass % aqueous solution of calcium acetate, the initial particle size increase rate from the start of mixing to 20 seconds after mixing begins is 30 nm / sec or more. <2> The above-mentioned method is used to form an image on a non-permeable recording medium. <1> 1. A set of the treatment liquid and ink described in <3> The flocculant is a divalent metal salt. <1> from <2> 1. A set of the treatment liquid and ink according to any one of the preceding items. <4> The content of the flocculant is 6% by mass or more relative to the total amount of the treatment liquid. <1> from <3> 1. A set of the treatment liquid and ink according to any one of the preceding items. <5> the non-white ink contains an acetylene glycol surfactant; The white ink contains a silicone surfactant. <1> from <4> 1. A set of the treatment liquid and ink according to any one of the preceding items. <6> The aforementioned <1> from <5> a treatment liquid application step of applying the treatment liquid of the treatment liquid and ink set according to any one of the above to a non-permeable recording medium; The aforementioned <1> from <5> a non-white ink applying step of applying a non-white ink in the set of treatment liquid and ink according to any one of the above items; The aforementioned <1> from <5> a white ink applying step of applying a white ink in the set of treatment liquid and ink according to any one of the above items; and a method for forming an image, the method comprising: <7> The total amount of the non-white ink and the white ink applied is 20 μg / inch 2 The above-mentioned <6> 1. An image forming method according to claim 1. <8> a non-white ink drying step of drying the non-white ink between the non-white ink applying step and the white ink applying step; <6> from <7> 1. The image forming method according to claim 1, wherein the first and second electrodes are arranged parallel to each other. <9> The aforementioned <1> from <5> a treatment liquid containing means for containing the treatment liquid in the treatment liquid and ink set according to any one of the above items; The aforementioned <1> from <5> an ink storage means for storing the non-white ink and the white ink in the treatment liquid and ink set according to any one of the above items; a treatment liquid applying means for applying the treatment liquid to a non-permeable recording medium; a non-white ink applying means for applying the non-white ink; a white ink applying means for applying the white ink; The image forming apparatus has the above.

[0117] The aforementioned <1> from <5> a set of a treatment liquid and an ink according to any one of the preceding claims, <6> from <8> and the image forming method according to any one of the preceding claims. <9> According to the image forming apparatus described in the above, the conventional problems can be solved and the object of the present invention can be achieved. [Explanation of symbols]

[0118] 100 Image forming device 110 Pre-treatment liquid application section 120 Ink application unit 130 Post-processing liquid application unit 140 Drying section 150 Conveyor M Recording medium [Prior art documents] [Patent documents]

[0119] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-156995

Claims

1. a treatment liquid containing a flocculant; a non-white ink containing a colorant other than white and an acetylene glycol surfactant; a white ink containing a white pigment dispersion and a silicone surfactant; and The content of the flocculant is 6% by mass or more relative to the total amount of the treatment liquid, The white pigment dispersion contains a white colorant, a dispersant having an anionic functional group, and water, the content of the dispersant is 5% by mass or more and 11% by mass or less with respect to the total amount of the white pigment dispersion, A set of a treatment liquid and an ink, characterized in that when a 1 volume % aqueous solution obtained by diluting the white ink with water is mixed with a 1 mass % aqueous solution of calcium acetate, the initial particle size increase rate from the start of mixing to 20 seconds after mixing is 30 nm / sec or more.

2. 10. The treatment liquid and ink set according to claim 1, which is used to form an image on a non-porous recording medium.

3. 3. The set of treatment liquid and ink according to claim 1, wherein the aggregating agent is a divalent metal salt.

4. The set of treatment liquid and ink according to claim 1 , wherein the content of the aggregating agent is 9% by mass or less with respect to the total amount of the treatment liquid.

5. 5. The treatment liquid and ink set according to claim 1, wherein the non-white ink has a surface tension of 20 mN / m or more and 45 mN / m or less at 25[deg.]C.

6. a treatment liquid applying step of applying the treatment liquid of the treatment liquid and ink set according to any one of claims 1 to 5 to a non-permeable recording medium; a non-white ink applying step of applying a non-white ink in the set of treatment liquid and ink according to any one of claims 1 to 5; a white ink applying step of applying a white ink in the set of treatment liquid and ink according to any one of claims 1 to 5; An image forming method comprising:

7. The total amount of the non-white ink and the white ink applied is 20 μg / inch ２ 7. The image forming method according to claim 6, wherein:

8. 8. The image forming method according to claim 6, further comprising, between the non-white ink applying step and the white ink applying step, a non-white ink drying step of drying the non-white ink.

9. a treatment liquid containing means for containing the treatment liquid in the treatment liquid and ink set according to any one of claims 1 to 5; an ink containing means for containing the non-white ink and the white ink in the treatment liquid and ink set according to any one of claims 1 to 5; a treatment liquid applying means for applying the treatment liquid to a non-permeable recording medium; a non-white ink applying means for applying the non-white ink; a white ink applying means for applying the white ink; An image forming apparatus having the same.

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