Active energy ray curable inkjet ink set, inkjet ink recording method, and printed material

Abstract

This invention provides an active energy ray-curable inkjet ink set that enhances the adhesion of white ink to a recording medium, improves the gloss of printed materials, enhances the color development of colored inks, and suppresses bleeding of colored inks when printing with active energy ray-curable inkjet inks on a recording medium. [Solution] An active energy ray-curable inkjet ink set comprising a white ink and a colored ink, wherein the white ink contains a photopolymerizable compound and a photopolymerization initiator, and the content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less of the total amount of the photopolymerizable compound contained in the white ink, and the colored ink comprises a photopolymerizable compound, a photopolymerization initiator, a colorant, and a gelling agent.

Description

[Technical Field]

[0001] The present disclosure relates to an active energy ray-curable inkjet ink set, an inkjet ink recording method, and a printed matter. [Background Art]

[0002] The inkjet ink recording method is a recording method that ejects ink droplets from very fine nozzles and deposits the ink droplets on a recording medium to form characters and images. This method has been widely used in recent years because it is easier to achieve full-color printing compared to other recording methods, and has the advantage that high-resolution images can be obtained even with an apparatus having a simple configuration.

[0003] Conventionally, as a technique for providing an ink set that can improve the adhesion of a coating film to a recording medium when an image is formed by overcoating and can ensure the wetting and spreading of the upper layer ink, there has been proposed an ink set of a radiation-curable inkjet composition including a lower layer ink and an upper layer ink, wherein the lower layer ink contains, as a polymerizable compound, a monofunctional polymerizable compound in an amount of 80.0% by mass or more based on the total amount of the polymerizable compound, and contains a polymerizable compound having a nitrogen heterocyclic structure and / or a polymerizable compound having a hydroxyl group in a total amount of 55.0% by mass or more based on the total amount of the polymerizable compound (see, for example, Patent Document 1). [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] An object of one aspect of the present disclosure is to provide an active energy ray-curable inkjet ink set that can improve the adhesion of white ink to a recording medium, the glossiness of a printed matter, and the color developability of colored ink when printing the active energy ray-curable inkjet ink on the recording medium, and can also suppress bleeding of the colored ink. [Means for Solving the Problem]

[0005] One aspect of the present disclosure as a means for solving the problem is an active energy ray-curable inkjet ink set comprising a white ink and a colored ink, wherein the white ink contains a photopolymerizable compound and a photopolymerization initiator, the content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less of the total amount of the photopolymerizable compound contained in the white ink, and the colored ink is an active energy ray-curable inkjet ink set comprising a photopolymerizable compound, a photopolymerization initiator, a colorant and a gelling agent. [Effects of the Invention]

[0006] According to one aspect of this disclosure, it is possible to provide an active energy ray-curable inkjet ink set that can improve the adhesion of white ink to a recording medium, the glossiness of the printed material, and the color development of colored ink when printing with an active energy ray-curable inkjet ink on a recording medium, and can also suppress bleeding of colored ink. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram illustrating an example of an image forming apparatus according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0008] The embodiments of this disclosure will be described in detail below. Unless otherwise specified, the "~" in the specification indicating a numerical range means that the numbers before and after it are included as the lower and upper limits.

[0009] [Activated Energy Ray Curing Inkjet Ink Set] An active energy ray curable inkjet ink set according to one embodiment of the present disclosure includes a white ink and a colored ink.

[0010] <Activated energy rays> The active energy rays used to cure the active energy ray-curable inkjet inks of this disclosure are not limited to ultraviolet light, but can also include electron beams, alpha rays, beta rays, gamma rays, X-rays, etc., as long as they can provide the energy necessary to advance the polymerization reaction of the polymerizable components in the inkjet ink. In particular, when using a high-energy light source, the polymerization reaction can be advanced without the use of a polymerization initiator. Furthermore, in the case of ultraviolet irradiation, there is a strong desire for mercury-free solutions from an environmental protection standpoint, and replacing mercury with GaN-based semiconductor ultraviolet light-emitting devices is extremely useful both industrially and environmentally. In addition, ultraviolet light-emitting diodes (UV-LEDs) and ultraviolet laser diodes (UV-LDs) are small, have a long lifespan, are highly efficient, and are low-cost, making them preferable as ultraviolet light sources.

[0011] (White ink) The white ink contains at least a photopolymerizable compound and a photopolymerization initiator, and optionally further contains other components such as colorants and organic solvents.

[0012] One characteristic of the white ink is that the content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less of the total amount of the photopolymerizable compound contained in the white ink. This improves adhesion and deformation responsiveness to recording media such as printing films, thereby enhancing the durability of printed materials.

[0013] Furthermore, the white ink according to one embodiment of this disclosure preferably contains substantially no gelling agent. This improves the leveling properties of the white ink from the time it is printed on a recording medium such as a film until it is cured by irradiation with active energy rays, thereby improving adhesion to the recording medium such as a film, and improving the gloss and color development of the colored ink. It should be noted that "substantially free" of the gelling agent means that the content is preferably less than 0.1% by mass.

[0014] Furthermore, in one embodiment of the present disclosure, it is preferable that the difference between the dynamic surface tension at 15 milliseconds (ms) at 25°C and the dynamic surface tension at 1,500 ms at 25°C is between 0 mN / m and 3.0 mN / m. This improves the wettability of the colored ink, enabling the formation of a color image with a smooth surface, high gloss, and excellent color development.

[0015] In this disclosure, there are no particular limitations on the method for measuring the dynamic surface tension of the ink, and it can be measured using known equipment, for example, a portable dynamic surface tension meter, Dyno Tester (Yamato Scientific Co., Ltd.), can be used.

[0016] (Colored ink) The colored ink contains at least a photopolymerizable compound, a photopolymerization initiator, a colorant, and a gelling agent, and optionally further contains other components such as an organic solvent.

[0017] One characteristic of colored inks is that they contain colorants and gelling agents. This prevents mixing between adjacent dots during high-speed printing in single-pass film printing, resulting in blur-free images.

[0018] Furthermore, in one embodiment of this disclosure, it is preferable that the difference between the dynamic surface tension at 15 ms at 25°C and the dynamic surface tension at 1,500 ms at 25°C is 0 mN / m or more and 3.0 mN / m or less. This improves the wettability of the colored ink, enabling the formation of a color image with a smooth surface, high gloss, and excellent color development.

[0019] <Monofunctional photopolymerizable compound> Monofunctional photopolymerizable compounds used in white or colored inks (hereinafter sometimes referred to as "monofunctional monomers") are photopolymerizable compounds that contain one molecular structure within the molecule that undergoes a radical polymerization reaction upon irradiation with active energy rays.

[0020] The monofunctional monomer is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include phenoxyethyl acrylate, cyclic trimethylolpropane formal acrylate, isobornyl acrylate, acryloyl morpholine, N-vinylcaprolactam, and 2-(2-vinyloxyethoxy)ethyl acrylate. These may be used alone or in combination of two or more thereof.

[0021] The content of the monofunctional monomer in the white ink is not particularly limited as long as it is 50% by mass or more and 90% by mass or less based on the total amount of the photopolymerizable compound contained in the white ink, and can be appropriately selected depending on the purpose. However, it is preferably 60% by mass or more and 90% by mass or less, more preferably 70% by mass or more and 90% by mass or less, and particularly preferably 80% by mass or more and 85% by mass or less. When the content is 50% by mass or more and 90% by mass or less, curing shrinkage in the radical polymerization reaction is reduced, thereby improving the adhesion of the white ink to a recording medium.

[0022] The content of the monofunctional monomer in the colored ink is not particularly limited and may be appropriately selected depending on the purpose. For example, the content is 0% by mass or more and 90% by mass or less based on the total amount of the photopolymerizable compound contained in the colored ink.

[0023] <Photopolymerizable compounds other than monofunctional monomers> The photopolymerizable compounds other than monofunctional monomers used in white ink or colored ink (hereinafter sometimes referred to as "other polymerizable compounds") are not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include polyfunctional monomers and oligomers. These may be used alone or in combination of two or more thereof.

[0024] There are no particular restrictions on the polyfunctional monomers, and they can be appropriately selected depending on the purpose. Examples include polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate, tripropylene glycol triacrylate, trimethylolpropane (EO)9 triacrylate, trimethylolpropane (PO)3 triacrylate, and dipropylene glycol diacrylate. These may be used individually or in combination of two or more.

[0025] There are no particular restrictions on the oligomers used; they can be selected appropriately depending on the purpose. Examples include CN963J85 and CN2273 from Sartomer. These can be used individually or in combination of two or more types.

[0026] There are no particular restrictions on the content of other polymerizable compounds in the white ink, and they can be appropriately selected depending on the purpose. For example, the content may be 0% to 30% by mass relative to the total amount of photopolymerizable compounds contained in the white ink. Furthermore, there are no particular restrictions on the content of other polymerizable compounds in colored inks, and they can be appropriately selected depending on the purpose. For example, the content may be 50% to 100% by mass relative to the total amount of photopolymerizable compounds contained in the colored ink.

[0027] <Surfactants> White or colored inks may contain surfactants as needed. In this disclosure, surfactant means a compound having surface-active properties, excluding so-called "pigment dispersants."

[0028] There are no particular restrictions on the surfactant used; it can be appropriately selected depending on the purpose, for example, silicone surfactants. Surfactants may be used individually or in combination of two or more types.

[0029] There are no particular restrictions on the silicone surfactant, and it can be appropriately selected depending on the purpose. Examples include BYK302, BYK307, BYK327, BYK331, BYK332, and BYK333 from BIC Chemie Japan Co., Ltd., and TEGO Wet270 from Evonik.

[0030] There are no particular restrictions on the surfactant content in white or colored inks, and it can be appropriately selected depending on the purpose, but it is preferable that it be between 0.01% by mass and 2.0% by mass relative to the total amount of ink. Furthermore, by substantially omitting the surfactant, the difference between the dynamic surface tension of the ink at 15 ms at 25°C and the dynamic surface tension at 1,500 ms at 25°C can be set to between 0 mN / m and 3.0 mN / m. This improves the leveling properties of the colored ink, thereby improving its color development and gloss.

[0031] <Gelling agent> The colored ink contains a gelling agent that allows the ink to undergo a reversible sol-gel phase transition.

[0032] A gel is a structure in which substances lose their independent motion and aggregate due to interactions such as lamellar structures, polymer networks formed by non-covalent or hydrogen bonds, polymer networks formed by physical aggregation states, aggregate structures of fine particles, and interactions of precipitated microcrystals. Gelation refers to solidification, semi-solidification, or thickening accompanied by a rapid increase in viscosity or elasticity.

[0033] In this disclosure, "reversibly undergoes sol-gel phase transition with temperature" means that, with a change in temperature, the substance can reversibly transition (convert) between a sol state, which has low viscosity, high fluidity, and liquid-like properties, and a gel state, which has high viscosity and solid or semi-solid-like properties.

[0034] Furthermore, "sol-gel phase transition temperature" refers to the temperature at which the sol state changes (transitions) to a gel state. It is synonymous with terms such as gel transition temperature, gel dissolution temperature, gel softening temperature, sol-gel transition point, and gelation point.

[0035] The sol-gel transition temperature of the ink according to one embodiment of this disclosure is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably in the range of 30 to 100°C in order to improve ejection stability. Furthermore, the sol-gel transition temperature of the ink according to one embodiment of this disclosure is preferably between the ink temperature in the inkjet recording head and the temperature of the recording medium.

[0036] One method for measuring the sol-gel transition temperature is to place a gel-like test specimen on a heat plate, heat the heat plate, and measure the temperature at which the specimen's shape collapses. This temperature is then determined as the sol-gel phase transition temperature. Alternatively, it can be measured using a commercially available viscoelasticity measuring device (for example, the Physica MCR300).

[0037] The gelling agent content in the colored ink according to one embodiment of the present invention is not particularly limited and can be appropriately selected depending on the purpose, but in order to suppress sol-gel phase transition and blooming well, it is preferably 0.5 to 3.5% by mass and more preferably 0.7 to 3.0% by mass relative to the total mass of the ink.

[0038] There are no particular restrictions on the gelling agent, and it can be appropriately selected depending on the purpose. For example, dilignoseryl ketone, dibehenyl ketone, distearyl ketone (melting point 84°C), dieicosyl ketone, dipalmyl ketone (melting point 80°C), dimyristyl ketone, dilauryl ketone (melting point 68°C), lauryl myristyl ketone, lauryl palmityl ketone, myristyl palmityl ketone, myristyl stearyl ketone, myristyl behenyl ketone, palmityl stearyl ketone, palmityl behenyl ketone, stearyl behenyl ketone, behenyl behenate (melting point 70°C), eicosyl Examples include behenyl stearate (melting point 70°C), stearyl stearate (melting point 60°C), palmityl stearate, lauryl stearate, cetyl palmitate (melting point 54°C), stearyl palmitate, myristyl myristate (melting point 43°C), cetyl myristate (melting point 50°C), octyldodecyl myristate, stearyl oleate, stearyl erucate, stearyl linoleate, behenyl oleate, myricyl cerotate, stearyl montanate, behenyl montanate, arachidyl linoleate, palmityl triacontanoate, and lignoceryl lignocerate.

[0039] Examples of commercially available gelling agents include 10-Nonadecanone (manufactured by Tokyo Chemical Industry Co., Ltd.), 12-Tricosanone (manufactured by Tokyo Chemical Industry Co., Ltd.), 16-Hentriacontanone (manufactured by Tokyo Chemical Industry Co., Ltd.), 18-Pentatriacontanone (manufactured by Alfa Aeser), Hentriacontan-16-on (manufactured by Alfa Aeser), Kao Wax T1 (manufactured by Kao Corporation), Unistar M-2222SL (manufactured by NOF Corporation), Excepearl SS (manufactured by Kao Corporation, melting point 60℃), EMALEX CC-18 (manufactured by Nippon Emulsion Co., Ltd.), Amlepus PC (manufactured by Higher Alcohol Industry Co., Ltd.), Excepearl MY-M (manufactured by Kao Corporation), Sperm Acetate (manufactured by NOF Corporation), EMALEX CC-10 (manufactured by Nippon Emulsion Co., Ltd.), and SS-EMALEX. Examples include EG-di-S (manufactured by Nippon Emulsion Co., Ltd.) and Poem B-100 (manufactured by Riken Vitamin Co., Ltd.). Since these commercially available products are often mixtures of two or more types, they may be separated and purified as needed.

[0040] Any known gelling agent other than those mentioned above can also be used.

[0041] For example, aliphatic ketone compounds; aliphatic ester compounds; petroleum-based waxes such as paraffin wax, microcrystalline wax, and petrolactam; plant-based waxes such as candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, jojoba solid wax, and jojoba esters; animal-based waxes such as beeswax, lanolin, and whale wax; mineral waxes such as montan wax and hydrogenated wax; hydrogenated castor oil or hydrogenated castor oil derivatives; montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives, or polyethylene wax Modified waxes such as derivatives; higher fatty acids such as behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, and erucic acid; higher alcohols such as stearyl alcohol and behenyl alcohol; hydroxystearic acid such as 12-hydroxystearic acid; 12-hydroxystearic acid derivatives; fatty acid amides such as lauric acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide, and 12-hydroxystearic acid amide (for example, Nikka Amid series manufactured by Nippon Chemical Corporation and manufactured by Ito Oil Co., Ltd.) ITOWAX series, Kao Corporation's FATTYAMID series, etc.; N-substituted fatty acid amides such as N-stearyl stearate amide and N-oleyl palmitate amide; special fatty acid amides such as N,N'-ethylenebisstearylamide, N,N'-ethylenebis-12-hydroxystearylamide and N,N'-xylylenebisstearylamide; higher amines such as dodecylamine, tetradecylamine, and octadecylamine; fatty acid ester compounds such as stearyl stearate, oleyl palmitic acid, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, ethylene glycol fatty acid ester, and polyoxyethylene fatty acid ester (e.g., Nippon Emulsion Co., Ltd.'s EMALLEX series, Riken Vitamin Co., Ltd.'s Rikemar series, Riken Vitamin Co., Ltd.'s Poem series, etc.); sucrose fatty acid esters such as sucrose stearic acid and sucrose palmitic acid (e.g., Ryoto Sugar Ester series manufactured by Mitsubishi Chemical Foods Co., Ltd.);Synthetic waxes such as polyethylene wax and α-olefin maleic anhydride copolymer wax (e.g., Baker-Petrolite's UNILIN series); dimer acids; dimer diols (e.g., CRODA's PRIPOR series); fatty acid inulins such as inulin stearate; fatty acid dextrins such as dextrin palmitate and dextrin myristate (e.g., Chiba Flour Milling Co., Ltd.'s Leopal series); glyceryl eicosanedioate behenate; polyglyceryl eicosanedioate behenate (e.g., Nisshin Oillio's NOMUCOAT series); amide compounds such as N-lauroyl-L-glutamic acid dibutylamide and N-(2-ethylhexanoyl)-L-glutamic acid dibutylamide (available from Ajinomoto Fine Techno); 1,3:2,4-bis-O-benzylidene-D-glucitol (Gelol D Examples include dibenzylidenesorbitols (available from Shin Nippon Rika), low molecular weight oil gelling agents described in Japanese Patent Publication No. 2005-126507, Japanese Patent Publication No. 2005-255821, and Japanese Patent Publication No. 2010-111790.

[0042] The gelling agent may be used alone or in combination of two or more types. Furthermore, commercially available products are often mixtures of two or more types, so separation and purification may be performed as necessary.

[0043] <Photopolymerization initiator> The active energy ray curable inkjet ink of this disclosure contains a photopolymerization initiator. The photopolymerization initiator can be any agent capable of generating active species such as radicals or cations using the energy of the active energy ray, thereby initiating the polymerization of a photopolymerizable compound (monomer or oligomer). Such a photopolymerization initiator can be a known radical polymerization initiator, cationic polymerization initiator, base generator, etc., used individually or in combination of two or more, and the use of a radical polymerization initiator is preferred. Furthermore, in order to obtain a sufficient curing rate, the photopolymerization initiator is preferably contained in an amount of 5 to 20% by mass relative to the total mass (100% by mass) of the inkjet ink.

[0044] Examples of radical polymerization initiators include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having carbon-halogen bonds, and alkylamine compounds.

[0045] In addition to the polymerization initiator mentioned above, a polymerization accelerator (sensitizer) can also be used in combination. The polymerization accelerator is not particularly limited, but preferred examples include amine compounds such as trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, 2-ethylhexyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, and 4,4'-bis(diethylamino)benzophenone, and their content can be appropriately set depending on the polymerization initiator used and the amount thereof.

[0046] <Colorants> The white ink in the active energy ray curable inkjet ink set of this disclosure may contain a colorant. The colored ink in the active energy ray curable inkjet ink set of this disclosure contains a colorant. As the colorant, various pigments and dyes that impart black, white, magenta, cyan, yellow, green, orange, glossy colors such as gold and silver can be used, depending on the purpose and required characteristics of the inkjet ink in this disclosure. The amount of colorant can be appropriately determined considering the desired color density and dispersibility in the inkjet ink, and is not particularly limited, but is preferably 0.1 to 20% by mass of the total mass (100% by mass) of the inkjet ink. The active energy ray curable inkjet ink of this disclosure may be colorless and transparent without a colorant, in which case it is suitable, for example, as an overcoat layer for protecting an image.

[0047] Inorganic or organic pigments can be used as the pigment, and they may be used individually or in combination of two or more.

[0048] As inorganic pigments, for example, carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, as well as iron oxide and titanium oxide can be used.

[0049] Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye chelates (e.g., basic dye type chelates, acid dye type chelates, etc.); dye lakes (basic dye type lakes, acid dye type lakes); nitro pigments; nitroso pigments; aniline black; and daylight fluorescent pigments.

[0050] Furthermore, to improve the dispersibility of the pigment, a dispersant may be further included. The dispersant is not particularly limited, but examples include dispersants commonly used to prepare pigment dispersions, such as polymer dispersants.

[0051] Suitable dyes include, for example, acid dyes, direct dyes, reactive dyes, and basic dyes. These may be used individually or in combination of two or more types.

[0052] <organic solvents> The active energy ray curable inkjet ink of the present invention may contain organic solvents, but it is preferable that it does not contain them if possible. If the composition does not contain organic solvents, especially volatile organic compounds (VOC-free), the safety of the place where the composition is handled will be further enhanced, and it will be possible to prevent environmental pollution. Note that "organic solvent" refers to common non-reactive organic solvents such as ether, ketone, xylene, ethyl acetate, cyclohexanone, and toluene, and should be distinguished from reactive monomers. Furthermore, "does not contain" organic solvents means substantially does not contain them, and it is preferable that the amount is less than 0.1% by mass.

[0053] <Other ingredients> The active energy ray-curable inkjet inks of this disclosure may optionally contain other known components other than those described above. Other components other than those described above are not particularly limited, but include, for example, conventionally known polymerization inhibitors, leveling agents, defoaming agents, fluorescent whitening agents, penetration enhancers, wetting agents (moisturizers), fixing agents, viscosity stabilizers, fungicides, preservatives, antioxidants, ultraviolet absorbers, chelating agents, pH adjusters, and thickeners.

[0054] <Preparation of Active Energy Ray Curable Composition> The active energy ray curable inkjet ink of this disclosure can be prepared using the various components described above, and the means and conditions for its preparation are not particularly limited. For example, polymerizable monomers, pigments, dispersants, etc., can be introduced into a disperser such as a ball mill, kitty mill, disc mill, pin mill, or dyno mill, dispersed to prepare a pigment dispersion, and then polymerizable monomers, initiators, polymerization inhibitors, surfactants, etc., can be further mixed into the pigment dispersion to prepare the ink.

[0055] <Viscosity> The viscosity of the active energy ray curable inkjet ink of this disclosure is not particularly limited and can be adjusted as appropriate depending on the application and means of application. For example, when an ejection means is applied to eject the inkjet ink from a nozzle, the viscosity in the range of 20°C to 65°C, preferably at 25°C, is 3 to 40 mPa·s, more preferably 5 to 15 mPa·s, and particularly preferably 6 to 12 mPa·s. It is also particularly preferable that this viscosity range is satisfied without containing the above-mentioned organic solvent. The viscosity can be measured using a cone-plate type rotational viscometer VISCOMETER TVE-22L manufactured by Toki Sangyo Co., Ltd., using a cone rotor (1°34'×R24), a rotation speed of 50 rpm, and setting the temperature of the constant temperature circulating water as appropriate in the range of 20°C to 65°C. VISCOMATE VM-150III can be used to adjust the temperature of the circulating water.

[0056] <Application> The applications of the active energy ray curable inkjet inks disclosed herein are not particularly limited and can be selected as appropriate depending on the purpose, but they are particularly suitable for use in the label packaging field where printing is done on film.

[0057] The active energy ray curable inkjet ink of this disclosure can be used not only as an ink to form two-dimensional characters, images, and decorative coatings on various substrates, but also as a material for forming three-dimensional objects (three-dimensional molded objects). This material for forming three-dimensional objects may be used, for example, as a binder between powder particles in a powder lamination method that performs three-dimensional molding by repeatedly curing and laminating powder layers, or as a three-dimensional constructing material (model material) or a supporting member (support material).

[0058] A known 3D modeling apparatus can be used to create a three-dimensional object using the active energy ray curable inkjet ink of this disclosure, and is not particularly limited, but examples include an apparatus equipped with a means for containing, supplying, and ejecting the inkjet ink, and an active energy ray irradiation means.

[0059] Furthermore, this disclosure also includes molded products obtained by processing cured products obtained by curing active energy ray-curable inkjet inks, or structures formed on a substrate using such cured products. These molded products are, for example, obtained by subjecting sheet-like or film-like cured products or structures to molding processes such as heat stretching or punching, and are suitably used in applications where surface decoration is required before molding, such as panels for meters and control sections in automobiles, office automation equipment, electrical and electronic equipment, and cameras.

[0060] The above-mentioned substrate is not particularly limited and can be appropriately selected depending on the purpose. Examples include paper, yarn, fibers, fabrics, leather, metal, plastic, glass, wood, ceramics, or composite materials thereof. From the viewpoint of processability, plastic substrates are preferred.

[0061] The active energy ray curable inkjet ink of this disclosure can also be used as an active energy ray curable composition. There are no particular restrictions on the applications of the active energy ray curable composition as long as it is in a field where active energy ray curable materials are generally used, and it can be appropriately selected according to the purpose. Examples include molding resins, paints, adhesives, insulating materials, mold release agents, coating materials, sealing materials, various resists, and various optical materials.

[0062] [Inkjet ink container] The inkjet ink container of this disclosure refers to a container containing active energy ray-curable inkjet ink, and is suitable for use in the applications described above. For example, the container containing the active energy ray-curable inkjet ink of this disclosure can be used as an ink cartridge or ink bottle, thereby eliminating the need to directly touch the ink during tasks such as ink transport and ink replacement, and preventing contamination of hands and clothing. It also prevents the contamination of the ink with foreign matter such as dust. Furthermore, the shape, size, and material of the container itself are not particularly limited and should be suitable for the application and usage, but it is desirable that the material be a light-shielding material that does not transmit light, or that the container be covered with a light-shielding sheet or the like.

[0063] [Inkjet ink recording method] An inkjet ink recording method according to one embodiment of the present disclosure includes at least a white ink area formation step, a colored ink area formation step, and a curing step, and optionally includes other steps.

[0064] <White ink area formation process> The white ink region formation process involves applying white ink to a recording medium to form a white ink region. The white ink region is formed in the layer below the colored ink region, which will be described later.

[0065] <Process for forming colored ink areas> The colored ink region formation process involves applying colored ink onto a white ink region to form a colored ink region. The colored ink region is formed on top of the white ink region.

[0066] <Curing process> The curing process involves forming a colored ink region and then irradiating it with active energy rays to cure both the white ink region and the colored ink region. The ink is cured through this curing process, and a printed material is obtained.

[0067] <Other processes> Other processes are not particularly limited as long as they do not impair the effects of this disclosure, and can be appropriately selected depending on the purpose. Examples include intermediate curing processes.

[0068] -Intermediate curing process- The intermediate curing process is a step performed between the white ink region formation process and the colored ink region formation process, in which the white ink region is cured by irradiating it with active energy rays.

[0069] There are no particular restrictions on the degree of hardening in the intermediate hardening process, and it can be appropriately selected according to the purpose. For example, it may be hardened to the extent that it prevents the ink from running or mixing (sometimes referred to as "partial hardening" or "preliminary hardening").

[0070] The curing in the intermediate curing process can be carried out, for example, by irradiating with a weaker active energy ray than that used in the curing process described above.

[0071] Furthermore, when using multiple colored inks, an intermediate curing process for the colored inks can be performed to partially cure them while each colored ink is forming a colored ink region. When performing the intermediate curing process for the colored inks, it may be performed for all colored inks, or it may be performed for any of the colored inks.

[0072] In an inkjet ink recording method according to one embodiment of the present disclosure, the white ink contains a photopolymerizable compound and a photopolymerization initiator, and the content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less of the total amount of photopolymerizable compound contained in the white ink. In addition, the colored ink in an inkjet ink recording method according to one embodiment of the present disclosure contains a photopolymerizable compound, a photopolymerization initiator, a colorant, and a gelling agent.

[0073] In the inkjet ink recording method according to one embodiment of this disclosure, the white ink and colored ink can preferably be inks having the same configuration as the white ink and colored ink in the active energy ray curable inkjet ink set described above.

[0074] An inkjet ink recording method according to one embodiment of this disclosure can be carried out, for example, by an image forming apparatus described later.

[0075] <Recording medium> There are no particular restrictions on the recording medium used for recording; it can be appropriately selected according to the purpose. Examples include transparent films such as PET film and OPP film.

[0076] <Application> The inkjet ink recording method disclosed herein is not particularly limited and can be appropriately selected depending on the purpose, but it is particularly suitable for use in the label packaging field where printing is done on film.

[0077] [Printed material] Furthermore, this disclosure also relates to printed materials obtained by recording using an inkjet ink recording method according to one embodiment of this disclosure.

[0078] [Image formation method, image formation apparatus] An image forming method according to one embodiment of the present disclosure includes at least an irradiation step of irradiating with active energy rays to cure an active energy ray-curable inkjet ink according to one embodiment of the present disclosure. An image forming apparatus according to one embodiment of the present disclosure includes an irradiation means for irradiating with active energy rays and a storage section for storing the active energy ray-curable inkjet ink according to one embodiment of the present disclosure, the storage section may contain the container. Furthermore, the image forming method and the image forming apparatus may have an ejection step or ejection means for ejecting the active energy ray-curable inkjet ink. The ejection method is not particularly limited, but examples include continuous ejection type and on-demand type. Examples of on-demand type ejection include piezo type, thermal type and electrostatic type.

[0079] Figure 1 shows an example of an image forming apparatus equipped with an inkjet ejection mechanism. Each color printing unit 23a, 23b, 23c, 23d, and 23e, each equipped with an ink cartridge and ejection head for white, yellow, magenta, cyan, and black active energy ray curable inks, ejects ink onto the recording medium 22 supplied from the supply roll 21. Subsequently, the ink is cured by irradiating it with active energy rays from light sources 24a, 24b, 24c, 24d, and 24e to form a color image. After that, the recording medium 22 is transported to the processing unit 25 and the printed material winding roll 26. Each color printing unit 23a, 23b, 23c, 23d, and 23e may be equipped with a heating mechanism to liquefy the ink at the ink ejection section. Additionally, a mechanism for cooling the recording medium to room temperature by contact or non-contact may be provided as needed. Furthermore, as an inkjet ink recording method, either a serial method, in which the head moves to eject ink onto a recording medium that moves intermittently according to the width of the ejection head, or a line method, in which the recording medium moves continuously and ink is ejected onto the recording medium from a head held in a fixed position, can be applied.

[0080] The recording medium 22 is not particularly limited, but examples include paper, film, metal, composite materials thereof, etc., and may be in the form of a sheet. Furthermore, it may be configured to allow only single-sided printing, or to allow both single-sided and double-sided printing.

[0081] Furthermore, the irradiation of active energy rays from light sources 24a, 24b, 24c, and 24d may be weakened or omitted, and after printing multiple colors, the irradiation of active energy rays from light source 24e may be performed. This can lead to energy savings and cost reduction.

[0082] Recordings made with the inks of this disclosure (also referred to as "printed materials") include not only those printed on smooth surfaces such as ordinary paper or resin film, but also those printed on uneven surfaces and those printed on surfaces made of various materials such as metal and ceramic. Furthermore, by stacking two-dimensional images, it is possible to form images with a partially three-dimensional appearance (images consisting of two and three dimensions) or three-dimensional objects. [Examples]

[0083] Examples of embodiments of this disclosure will be further described below with reference to examples and comparative examples, but this disclosure is not limited to these examples and comparative examples.

[0084] (Manufacturing of white pigment dispersion A) The two compounds shown below were placed in a stainless steel beaker. This was heated on a hot plate at 65°C and stirred for 1 hour. • Phenoxyethyl acrylate (Viscote 192, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 52 parts by mass • Dispersant (BYKJET-9151: manufactured by BYK, "BYKJET" is a registered trademark of the company) 8 parts by mass

[0085] After cooling to room temperature, 40 parts by mass of titanium dioxide (TCR-52; manufactured by Sakai Chemical Industry Co., Ltd.) with an average particle size of 200 nm was added, and the mixture was placed in a glass bottle with 220 g of zirconia beads with a diameter of 0.5 mm and sealed tightly. After dispersion treatment in a paint shaker for 5 hours, the zirconia beads were removed to obtain white pigment dispersion A.

[0086] (Manufacturing of white pigment dispersion B) The two compounds shown below were placed in a stainless steel beaker. This was heated on a hot plate at 65°C and stirred for 1 hour. • Tripropylene glycol diacrylate (Miramer M200: manufactured by Miwon, "Miramer" is a registered trademark of the company) 52 parts by mass • Dispersant (BYKJET-9151: manufactured by BYK) 8 parts by mass

[0087] After cooling to room temperature, 40 parts by mass of titanium dioxide (TCR-52; manufactured by Sakai Chemical Industry Co., Ltd.) with an average particle size of 200 nm was added, and the mixture was placed in a glass bottle with 220 g of zirconia beads with a diameter of 0.5 mm and sealed tightly. After dispersion treatment in a paint shaker for 5 hours, the zirconia beads were removed to obtain white pigment dispersion B.

[0088] (Manufacturing of colored pigment dispersions) Black pigment dispersion A, cyan pigment dispersion A, magenta pigment dispersion A, and yellow pigment dispersion A were manufactured as follows.

[0089] The two compounds shown below were placed in a stainless steel beaker. This was heated on a hot plate at 65°C and stirred for 1 hour. • Dipropylene glycol diacrylate (APG-100, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 242) 71 parts by mass • Dispersant (BYKJET-9151: manufactured by BYK) 9 parts by mass

[0090] After cooling to room temperature, 20 parts by mass of one of the following pigments was added to it, and the mixture was placed in a glass bottle with 200 g of 0.5 mm diameter zirconia beads and sealed tightly. After dispersion treatment in a paint shaker for the time specified below, the zirconia beads were removed to obtain a colored pigment dispersion. • Black pigment dispersion A: Pigment Black 7 (manufactured by Mitsubishi Chemical Corporation, #52), dispersion processing time: 5 hours • Cyan pigment dispersion A: Pigment Blue 15:4 (manufactured by Dainichi Seika Co., Ltd., Chromofine Blue 6332JC), dispersion processing time: 4 hours • Magenta pigment dispersion A: Mixed crystal of Pigment Violet19 and Red202 (BASF, CINQUASIA MAGENTA RT-355D), dispersion processing time: 6 hours • Yellow pigment dispersion A: Pigment Yellow 185 (BASF, D1155), dispersion time 6 hours

[0091] (Preparation of white ink 1-4, black ink 1-3, cyan ink 1, magenta ink 1, and yellow ink 1) The raw materials were mixed according to the formulations listed in Tables 1-3 below, and an ink mixture was obtained using a three-one motor. The ink was then filtered using a capsule filter with an absolute filtration accuracy of 1.0 μm, filled into clean bottles, and various inks were obtained. Note that the formulation amounts in Tables 1-3 are expressed as mass percent.

[0092] The raw materials used in addition to the pigment dispersion are as follows. Note that these are used as an example.

[0093] [Monofunctional monomer] • Phenoxyethyl acrylate (hereinafter sometimes referred to as "PEA"), manufactured by Osaka Organic Chemical Industry Co., Ltd. • Isobornyl acrylate (hereinafter sometimes referred to as "IBOA"), manufactured by Osaka Organic Chemical Industry Co., Ltd. • Acryloylmorpholine (hereinafter sometimes referred to as "ACMO"), manufactured by KJ Chemicals.

[0094] [Photopolymerizable compounds other than monofunctional monomers] -Polyfunctional monomer- • Polyethylene glycol (400) diacrylate (hereinafter sometimes referred to as "PEG400DA"), manufactured by Daiichi Kogyo Seiyaku Co., Ltd. • Polyethylene glycol (600) diacrylate (hereinafter sometimes referred to as "PEG600DA"), manufactured by Daiichi Kogyo Seiyaku Co., Ltd. • Tripropylene glycol diacrylate (hereinafter sometimes referred to as "TPGDA"), manufactured by Osaka Organic Chemical Industry Co., Ltd. • Trimethylolpropane (EO) 9 triacrylate (hereinafter sometimes referred to as "TMP(EO)9TA"), manufactured by Shin-Nakamura Chemical Co., Ltd. • Trimethylolpropane (PO)3 triacrylate (hereinafter sometimes referred to as "TMP(PO)3TA"), manufactured by Shin-Nakamura Chemical Co., Ltd. Tricyclodecanedimethanol diacrylate (hereinafter sometimes referred to as "R-684"), manufactured by Nippon Kayaku Co., Ltd. -Oligomer- • CN963J85 (hereinafter sometimes referred to as "CN963"), manufactured by Sartmar. • CN2273, manufactured by Sartmar.

[0095] [Photopolymerization initiator] • Omnirad TPO (hereinafter sometimes referred to as "TPO"), manufactured by IGM Resins. • Omnirad 819, manufactured by IGM Resins.

[0096] [Polymerization inhibitor] • Irgastab UV-10 (hereinafter sometimes referred to as "UV-10"), manufactured by BYK.

[0097] [Gelling agent] Behenyl behenate (hereinafter sometimes referred to as "M-2222SL"), manufactured by NOF Corporation. • Stearyl stearate (hereinafter sometimes referred to as "M-9676"), manufactured by NOF Corporation. • Cetyl myristate (hereinafter sometimes referred to as "sperm acetate"), manufactured by NOF Corporation.

[0098] [Surfactants] • BYK307, manufactured by BYK.

[0099] The dynamic surface tension of the prepared ink was measured at 25°C (15 milliseconds (ms) and 1,500 ms) using a portable dynamic surface tension meter, Dyno Tester (Yamato Scientific Co., Ltd.). The difference (mN / m) between the dynamic surface tension at 15 ms and 1,500 ms at 25°C is shown in Tables 1-3.

[0100] [Table 1]

[0101] [Table 2]

[0102] [Table 3]

[0103] (Examples 1-11, Comparative Examples 1-3) Printed materials were produced using the inks listed in the "Implementation Configuration" column of Tables 4-7 below, and a one-pass printer with the Ricoh MH5320 head shown in Figure 1. Specifically, solid images of each color ink were printed at 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction, an ejection droplet size of 15 pL, and an ejection frequency of 30 kHz, and the printed materials were produced by irradiating them with a 395 nm wavelength UV-LED. Note that "WoW" and "WoD" in the "Printing Process" column of the "Implementation Configuration" column of Tables 4-7 below indicate that the printing process was performed as follows.

[0104] "WoW" first forms an image using the white ink mentioned above, then forms an image using colored ink, and finally irradiates it with light from an LED lamp (manufactured by Phoseon Technology) (395nm, 16W / cm²). 2 The ink was cured. The distance from the LED lamp to the recording medium surface was 20 mm, and the transport speed of the recording medium was 1.2 m / s (light intensity, 300 mJ / cm²). 2 The light intensity was measured using an ultraviolet integrated light meter (Noblelight, UV Power Pack). In this example, the printing process was carried out as described above, but for example, UV-LED lamps could be installed between each of the colored ink ejection heads, and the UV level could be set to 100 mJ / cm². 2 The following steps involve irradiating with UV light of the following integrated intensity, partially curing each ink after image formation with the various inks, and then applying 300 mJ / cm² after image formation with all inks. 2 The printing process can also be carried out by including a step of curing the ink by irradiating it with the above-mentioned accumulated amount of UV light.

[0105] "WoD" installs a UV-LED lamp between the white ink ejection head and the colored ink ejection head, and after image formation with the white ink, it applies 100 mJ / cm² of UV-LED lamp. 2 The following integrated UV light intensity is applied to partially cure the white ink, and then, after image formation with all inks, including the colored inks, 300 mJ / cm² is applied. 2 The ink was cured by irradiating it with the above accumulated amount of UV light. In this example, the printing process was carried out as described above, but for example, UV-LED lamps could be installed between each of the colored ink ejection heads, and the UV level could be set to 100 mJ / cm². 2 The printing process can also be carried out by irradiating with UV light of the following cumulative light intensity, and then partially curing each of the inks after image formation.

[0106] [Quality Evaluation] The printed materials were evaluated for "film adhesion," "glossiness," "color development," and "colored ink bleeding" as described below. The results are shown in Tables 4-7.

[0107] <Film adhesion> The printed materials were subjected to a cross-cut test in accordance with JIS K5600-5-6 and evaluated according to the following criteria. ○ and △ indicate a pass. -Evaluation Criteria- ○: Classification 0 or 1 △: Classification 2 or 3 ×: Classification 4 or 5

[0108] <Glossiness> The glossiness of the printed materials was measured using a Vic Gardner Micro Tri-Gloss meter. Five points on the image were evaluated, and the average value was used as the glossiness. The evaluation was based on the glossiness value at 60°, according to the following criteria. ◎, ○, and △ indicate passing grades. -Evaluation Criteria- ◎: Glossiness value of 7.0 or higher at 60° ○: Glossiness value at 60° is 5.5 or higher and less than 7.0 △: Glossiness value at 60° is between 4.0 and 5.5. ×: Glossiness value at 60° is less than 4.0

[0109] <Color development> The colored ink images in the produced printed materials were evaluated using the following criteria based on saturation values ​​measured with X-Rite939. ○ and △ indicate a passing grade. -Evaluation Criteria- Black ink ○: OD is 1.3 or higher △: OD is 1.2 or higher but less than 1.3 ×: OD is less than 1.2 Cyan ink ○: Saturation level of 55 or higher △: Saturation is between 45 and 55 ×: Saturation less than 45 Magenta ink ○: Saturation level of 70 or higher △: Saturation is between 60 and 70 ×: Saturation less than 60 • Yellow ink ○: Saturation level of 85 or higher △: Saturation is between 80 and 85 ×: Saturation less than 80

[0110] <Colored ink bleeding> After printing a white ink base layer, a 100% solid yellow ink area and a 100% solid black ink area were printed adjacent to each other. The adjacent areas of the yellow and black inks were visually observed and evaluated according to the following criteria. ○ and △ indicate a pass. -Evaluation Criteria- ○: No blurring is visible to the naked eye. △: Slight blurring is visible. ×: Adjacent areas are unclear due to blurring.

[0111] [Table 4]

[0112] [Table 5]

[0113] [Table 6]

[0114] [Table 7]

[0115] From the results above, it has been confirmed that, according to one aspect of this disclosure, when printing active energy ray-curable inkjet ink onto a recording medium, the adhesion of white ink to the recording medium, the glossiness of the printed material, and the color development of colored ink can be improved, and bleeding of colored ink can be suppressed.

[0116] Examples of embodiments of the present disclosure are as follows: <1> An active energy ray curable inkjet ink set comprising white ink and colored ink, The aforementioned white ink contains a photopolymerizable compound and a photopolymerization initiator. The content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less, relative to the total amount of the photopolymerizable compound contained in the white ink. The aforementioned colored ink is an active energy ray curable inkjet ink set characterized by containing a photopolymerizable compound, a photopolymerization initiator, a colorant, and a gelling agent. <2> The white ink is substantially free of a gelling agent. <1> This is an active energy ray curing inkjet ink set as described above. <3> The difference between the dynamic surface tension of the white ink at 25°C at 15 ms and the dynamic surface tension at 25°C at 1,500 ms is between 0 mN / m and 3.0 mN / m. <1> or <2> This is an active energy ray curing inkjet ink set as described above. <4> The difference between the dynamic surface tension of the colored ink at 15 ms at 25°C and the dynamic surface tension at 1,500 ms at 25°C is between 0 mN / m and 3.0 mN / m. <1> from <3> This is an active energy ray curing inkjet ink set as described in any of the following. <5> A white ink region formation step involves applying white ink to a recording medium to form a white ink region, A colored ink region formation step involves applying colored ink to the white ink region to form a colored ink region, The process includes a curing step in which, after forming the colored ink region, an active energy ray is irradiated to cure the white ink region and the colored ink region, The aforementioned white ink contains a photopolymerizable compound and a photopolymerization initiator. The content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less, relative to the total amount of the photopolymerizable compound contained in the white ink. The aforementioned colored ink is characterized by containing a photopolymerizable compound, a photopolymerization initiator, a colorant, and a gelling agent. <6> The process between the white ink region formation step and the colored ink region formation step further includes an intermediate curing step in which the white ink region is cured by irradiating it with active energy rays. <5> This is the inkjet ink recording method described in [the relevant document]. <7> The white ink is substantially free of a gelling agent. <5> or <6> This is the inkjet ink recording method described in [the relevant document]. <8> The difference between the dynamic surface tension of the white ink at 25°C at 15 ms and the dynamic surface tension at 25°C at 1,500 ms is between 0 mN / m and 3.0 mN / m. <5> from <7> This is an inkjet ink recording method as described in one of the following. <9> The difference between the dynamic surface tension of the colored ink at 15 ms at 25°C and the dynamic surface tension at 1,500 ms at 25°C is between 0 mN / m and 3.0 mN / m. <5> from <8> This is an inkjet ink recording method as described in one of the following. <10> The aforementioned <5> from <9> This printed material is characterized by being obtained by recording using the inkjet ink recording method described in any of the above.

[0117] The aforementioned <1> from <4> Active energy ray curable inkjet ink set as described in any of the above, <5> from <9> The inkjet ink recording method described in any of the above, or the above <10> According to the printed materials described herein, it is possible to resolve conventional problems and achieve the objectives of this disclosure. [Explanation of Symbols]

[0118] 21 supply rolls 22 Recording media 23a, 23b, 23c, 23d, 23e Printing Units 24a, 24b, 24c, 24d, 24e light source 25 processing units 26 Printed material winding roll [Prior art documents] [Patent Documents]

[0119] [Patent Document 1] Japanese Patent Publication No. 2022-099495

Claims

1. An active energy ray curable inkjet ink set comprising white ink and colored ink, The aforementioned white ink contains a photopolymerizable compound and a photopolymerization initiator. The content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less, relative to the total amount of the photopolymerizable compound contained in the white ink. The aforementioned colored ink is characterized by containing a photopolymerizable compound, a photopolymerization initiator, a colorant, and a gelling agent, and is an active energy ray curable inkjet ink set.

2. The active energy ray curable inkjet ink set according to claim 1, wherein the white ink substantially does not contain a gelling agent.

3. The activated energy ray curable inkjet ink set according to claim 1 or 2, wherein the difference between the dynamic surface tension of the white ink at 25°C for 15 ms and the dynamic surface tension at 25°C for 1,500 ms is 0 mN / m or more and 3.0 mN / m or less.

4. The activated energy ray curable inkjet ink set according to claim 1 or 2, wherein the difference between the dynamic surface tension of the colored ink at 25°C for 15 ms and the dynamic surface tension at 25°C for 1,500 ms is 0 mN / m or more and 3.0 mN / m or less.

5. A white ink region formation step involves applying white ink to a recording medium to form a white ink region, A colored ink region formation step involves applying colored ink to the white ink region to form a colored ink region, The process includes a curing step in which, after forming the colored ink region, an active energy ray is irradiated to cure the white ink region and the colored ink region, The aforementioned white ink contains a photopolymerizable compound and a photopolymerization initiator. The content of the monofunctional photopolymerizable compound in the white ink is 50% by mass or more and 90% by mass or less, relative to the total amount of the photopolymerizable compound contained in the white ink. The inkjet ink recording method is characterized in that the colored ink contains a photopolymerizable compound, a photopolymerization initiator, a colorant, and a gelling agent.

6. The inkjet ink recording method according to claim 5, further comprising an intermediate curing step of irradiating the white ink region with active energy rays to cure it between the white ink region formation step and the colored ink region formation step.

7. The inkjet ink recording method according to claim 5, wherein the white ink substantially does not contain a gelling agent.

8. The inkjet ink recording method according to claim 5, wherein the difference between the dynamic surface tension of the white ink at 25°C for 15 ms and the dynamic surface tension at 25°C for 1,500 ms is 0 mN / m or more and 3.0 mN / m or less.

9. The inkjet ink recording method according to claim 5, wherein the difference between the dynamic surface tension of the colored ink at 25°C for 15 ms and the dynamic surface tension at 25°C for 1,500 ms is 0 mN / m or more and 3.0 mN / m or less.

10. A printed material characterized by being obtained by recording using the inkjet ink recording method described in any one of claims 5 to 9.

Images