Ink, ink container, printer and printing method

Abstract

To provide an ink capable of forming a printed matter with improved fastness and texture, while preventing a boundary face between a fixation resin and a pigment particle from being generated.SOLUTION: An ink includes a hollow resin particle and a fixation resin. A difference between a storage elastic modulus of the hollow resin particle at 25°C and a storage elastic modulus of the fixation resin at 25°C is 1.0×109 Pa or less. A storage elastic modulus at 25°C of an ink dry film obtained by desiccating the ink is 1.0×106 Pa to 1.0×108 Pa.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink, an ink container, a printing device, and a printing method. [Background technology]

[0002] Inkjet printing using textile inks requires high durability of the printed matter. Previous studies have shown that durability can be improved by lowering the storage modulus of the ink film below a specific value (Patent Document 1).

[0003] However, unlike other colors, white ink uses large, hard particles such as titanium oxide and hollow resin particles as pigment particles, which makes it easy for interfaces to form between the fixing resin particles and the pigment particles.In this case, the large difference in hardness (elastic modulus) between the fixing resin and the pigment particles causes problems such as poor durability and texture, even though the elastic modulus of the ink film is appropriate.

[0004] Patent Document 1 attempts to improve abrasion resistance and blocking resistance by specifying the elastic modulus of the ink film, not limited to white inks and not limited to inks in the textile field. Patent Document 2 also attempts to improve fabric conformability by ensuring that "the glass transition temperature of the hollow resin particles is 120°C or higher, and the glass transition temperature of the resin particles is 5°C or lower." Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to achieve the following object: That is, the present invention aims to provide an ink that can suppress the occurrence of interfaces between a fixing resin and pigment particles and can form printed matter with improved fastness and texture. [Means for solving the problem]

[0006] One aspect of the present invention is an ink containing hollow resin particles and a fixing resin, wherein the difference between the storage modulus of the hollow resin particles at 25°C and the storage modulus of the fixing resin at 25°C is 1.0 × 10 9 Pa or less, and the storage modulus of the dried ink film obtained by drying the ink at 25°C is 1.0 × 10 6 Pa or more 1.0×10 8 The ink is characterized by having a viscosity of 0.05 Pa or less. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an ink that can suppress the occurrence of interfaces between the fixing resin and the pigment particles and can form printed matter with improved fastness and texture. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of a printing device that uses the ink of the present invention. [Figure 2] FIG. 2 is a perspective view of the main tank that contains the ink of the present invention. [Figure 3] FIG. 3 is a diagram illustrating hollow particles. DETAILED DESCRIPTION OF THE INVENTION

[0009] Aspects of the embodiments of the present invention are, for example, as follows. <1> An ink containing hollow resin particles and a fixing resin, The difference between the storage modulus of the hollow resin particles at 25°C and the storage modulus of the fixing resin at 25°C is 1.0 × 10 9 Pa or less, The storage modulus of the dried ink film obtained by drying the ink at 25°C is 1.0 × 10 6 Pa or more 1.0×10 8 The ink is characterized by having a viscosity of 0.05 Pa or less. <2> The difference between the storage modulus of the hollow resin particles contained in the ink at 25°C and the storage modulus of the fixing resin at 25°C is 4.0 × 10 7Pa or less, <1> The ink is as described in <3> The hollow resin particles contained in the ink have a shell thickness / primary particle diameter ratio of 0.15 or less. <1> from <2> The ink is any one of the above. <4> The hollow resin particles contained in the ink have a shell thickness / primary particle diameter ratio of 0.10 or less. <1> from <3> The ink is any one of the above. <5> <1> from <4> 1. An ink container characterized in that the ink according to any one of the above items is contained in the container. <6> <5> and a discharge head for discharging ink. <7> On the recording medium <1> from <4> 1. A printing method for forming an image using the ink according to any one of claims 1 to 9.

[0010] (ink) The organic solvent, water, hollow resin particles, coloring material, fixing resin, additives, etc. used in the ink will be described below.

[0011] <Organic solvents> The organic solvent used in the present invention 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 alcohols, aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds. Specific examples of the water-soluble organic solvent 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, 2,4-pentanediol, 1,5-pentanediol, and the like. Polyhydric alcohols such as 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, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether. polyhydric alcohol alkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone; amides such as formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; amines such as monoethanolamine, diethanolamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; 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.

[0012] Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol. Specific examples of glycol ether compounds include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monobutyl ether, 1-methyl-1- Examples of the alkyl ethers include glycol ethers such as methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, and dipropylene glycol mono-iso-propyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0013] Polyol compounds having 8 or more carbon atoms and glycol ether compounds can improve the permeability of ink when paper is used as the recording medium.

[0014] The content of the organic solvent 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, 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.

[0015] <Water> 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.

[0016] <Hollow particles> A hollow particle consists of a shell layer and a void (hollow portion) surrounded by the shell layer. In the present invention, the hollow diameter of a hollow particle refers to the diameter of this hollow portion. The outer diameter of a hollow particle is called the primary particle diameter, and the thickness of the shell layer is called the shell thickness. In the present invention, hollow particles whose shell layer is made of a resin component are referred to as hollow resin particles, and hollow particles whose shell layer is made of an inorganic component are referred to as hollow inorganic particles.

[0017] -Hollow resin particles- The ink of the present invention contains hollow resin particles. Hollow resin particles are usually used as a white coloring material, but the ink of the present invention may also contain coloring materials other than the hollow resin particles. The hollow resin particles may be synthesized appropriately or commercially available. The synthesis method for the hollow resin particles is not particularly limited and can be appropriately selected depending on the purpose. However, a preferred method is the so-called emulsion polymerization method, in which a hollow resin particle emulsion is formed by heating and stirring a vinyl monomer, a surfactant, a polymerization initiator, and an aqueous dispersion medium under a nitrogen atmosphere. Specific production methods have been studied for a long time, and well-known examples include the "alkali swelling method" by Rohm & Haas (Japanese Patent Application Laid-Open No. 56-32513), the "polymerization shrinkage method" by Japan Synthetic Rubber Co., Ltd. (Japanese Patent Application Laid-Open No. 61-87734, Japanese Patent Application Laid-Open No. 62-127336), and the "phase separation method" by Sekisui Chemical Co., Ltd. (Japanese Patent Application Laid-Open No. 2005-146223).

[0018] Examples of the vinyl monomer include nonionic monofunctional ethylenically unsaturated monomers, difunctional vinyl monomers, trifunctional or higher vinyl monomers, etc. These may be used alone or in combination of two or more.

[0019] Examples of the nonionic monofunctional ethylenically unsaturated monomer include styrene, vinyltoluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth)acrylamide, and (meth)acrylic acid esters. These may be used alone or in combination of two or more. Among these, (meth)acrylic acid esters are preferred.

[0020] Examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate.

[0021] Examples of the bifunctional vinyl monomer include divinylbenzene, allyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,5-butanediol di(meth)acrylate, and diethylene glycol di(meth)acrylate.

[0022] Examples of the tri- or higher functional vinyl monomer include trimethylolpropane tri(meth)acrylate.

[0023] By copolymerizing the nonionic monofunctional ethylenically unsaturated monomer with at least one of the difunctional vinyl monomer and the trifunctional or higher vinyl monomer to achieve a high degree of crosslinking, hollow resin particles can be obtained that not only have light scattering properties but also have properties such as heat resistance, solvent resistance, and solvent dispersibility.

[0024] The surfactant may be any surfactant that forms molecular aggregates such as micelles in water, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. These surfactants may be used alone or in combination of two or more.

[0025] As the polymerization initiator, a known compound soluble in water can be used, such as hydrogen peroxide, potassium persulfate, etc. These may be used alone or in combination of two or more.

[0026] Examples of the aqueous dispersion medium include water and water containing a hydrophilic organic solvent.

[0027] The primary particle diameter and shell thickness of the hollow resin particles can be appropriately selected depending on the purpose, but the ratio of "shell thickness / primary particle diameter" is preferably 0.15 or less, more preferably 0.10 or less. When the ratio of "shell thickness / primary particle diameter" is 0.15 or less, the dry rub fastness, wet rub fastness, and washing fastness of the printed matter are improved, and when it is 0.10 or less, the printed matter can have even better fastnesses. The primary particle size and shell thickness can be measured, for example, using TEM images of particles in the ink observed with a transmission electron microscope (JEOL Ltd., "JEM-2100F"), or SEM images of the printing layer of a printed matter observed with a heated cathode field-effect scanning microscope (Schottky, FE-SEM, Carl Zeiss, ULTRA55).

[0028] The content of the hollow resin particles is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 3.0% by mass to 14.0% by mass, and more preferably 5.0% by mass to 12.5% by mass, based on the total amount of ink. When the content is 5.0% by mass or more, the whiteness of the printed image can be ensured. When the content is 12.5% by mass or less, the degree of sedimentation is excellent.

[0029] <Colorant> The coloring material of the ink of the present invention may contain a coloring material other than the hollow resin particles.

[0030] The coloring material 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. Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments. As inorganic pigments, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used. In addition, 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. In addition, resin hollow particles and inorganic hollow particles can also be 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). 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 Yellow CI Pigment Orange 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 34, 5, 17, 22, 23, 31, 38, 48:2, 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 (Red ochre), 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 Pigments Violet 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, CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.

[0031] 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, 173, 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.

[0032] The content of the coloring material in the ink is preferably from 0.1% to 15% by mass, more preferably from 1% to 10% by mass, from the viewpoints of improving image density, good fixability, and ejection stability.

[0033] Methods for dispersing a pigment to obtain an 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. An example of a 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. A pigment whose surface is coated with a resin and dispersed can be called a resin-coated pigment. When coating the surface of a pigment with a resin and dispersing it, it is not necessary for all of the pigments blended in the ink to be coated with a resin; uncoated or partially coated pigments may be dispersed in the 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. Paionin RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as dispersants. The dispersants may be used alone or in combination of two or more.

[0034] <Pigment dispersion> Ink can be obtained by mixing a pigment with water, an organic solvent, or other materials. Alternatively, ink can be produced by mixing a pigment with other materials such as water and a dispersant to form a pigment dispersion, and then mixing the resulting mixture with water, an organic solvent, or other materials. 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 II-UT151, manufactured by Microtrac MRB 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 that the pigment dispersion is degassed, if necessary, by filtering coarse particles using a filter, a centrifugal separator, or the like.

[0035] <Fixing resin> The type of fixing resin contained in the ink is not particularly limited and can be appropriately selected depending on the purpose, and examples include urethane resins, polyester resins, acrylic resins, vinyl acetate resins, styrene resins, butadiene resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, acrylic silicone resins, etc. Among these, urethane resins are preferred in that they are excellent in both mechanical strength and flexibility and can yield printed matter that has good dry rub fastness, wet rub fastness, wash fastness, and texture. 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.

[0036] 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 using, for example, a particle size analyzer (Nanotrac WaveII-UT151, manufactured by Microtrac MRB Co., Ltd.).

[0037] The content of the fixing resin is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of fixability and storage stability of the ink, however, it is preferably from 1% by mass to 30% by mass, and more preferably from 5% by mass to 20% by mass, of the total amount of ink.

[0038] The particle size of the solid content in the ink is not particularly limited and can be selected appropriately depending on the purpose. However, in order to improve image quality such as ejection stability and image density, the maximum frequency of particle sizes of the solid content in the ink, calculated as the maximum number, is preferably 20 nm to 1000 nm, more preferably 20 nm to 150 nm. The solid content includes resin particles, pigment particles, etc. The particle size can be measured using a particle size analyzer (Nanotrac Wave II-UT151, manufactured by Microtrac MRB Co., Ltd.).

[0039] <Additives> If necessary, surfactants, antifoaming agents, antiseptic and antifungal agents, antirust agents, pH adjusters, etc. may be added to the ink.

[0040] -Surfactants- As the surfactant, any of silicone surfactants, fluorine surfactants, acetylene glycol surfactants, amphoteric surfactants, nonionic surfactants and anionic surfactants can be used. Silicone surfactants are not particularly limited and can be appropriately selected depending on the purpose.Among them, those that do not decompose even at high pH are preferred, such as side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end modified polydimethylsiloxane of side chain, and those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying 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, and examples thereof include compounds in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane. 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. Acetylene glycol surfactants are nonionic surfactants with a central acetylene group and a symmetrical structure. They are "wetting agents that do not foam easily" and are environmentally friendly. 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. These may be used alone or in combination of two or more.

[0041] The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include side-chain-modified polydimethylsiloxane, both-end-modified polydimethylsiloxane, one-end-modified polydimethylsiloxane, and both-end-modified side-chain polydimethylsiloxane. Polyether-modified silicone surfactants having a polyoxyethylene group or a polyoxyethylene-polyoxypropylene group as the modifying group are particularly preferred because they exhibit good properties as aqueous surfactants. Such surfactants may be appropriately synthesized or commercially available products, such as those available from BYK-Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd. The polyether-modified silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, it may be a surfactant represented by general formula (S-1) in which a polyalkylene oxide structure is introduced into the Si moiety side chain of dimethylpolysiloxane. [ka] (In the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R' represents an alkyl group.)

[0042] As the polyether-modified silicone surfactant, commercially available products can be used, for example, KF-353, KF-640, KF-642, KF-643, KF-644 (manufactured by Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5051 (manufactured by Nippon Emulsion Co., Ltd.), BYK-345, BYK-347, BYK-348, BYK-375, BYK-377 (manufactured by BYK Japan Co., Ltd.), Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG503A, Silface SAG008 (manufactured by Nissin Chemical Co., Ltd.), TEGO_Wet_KL245, TEGO_Wet_250, TEGO_Wet_260, TEGO_Wet_265, TEGO_Wet_270, TEGO_Wet_280 (manufactured by Evonik Japan Co., Ltd.), and the like.

[0043] The fluorine-based surfactant is preferably a compound having 2 to 16 fluorine-substituted carbon atoms, more preferably a compound having 4 to 16 fluorine-substituted carbon atoms. Examples of fluorine-based surfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chains. Among these, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chains are preferred because they have low foaming properties, and fluorine-based surfactants represented by general formula (F-1) and general formula (F-2) are particularly preferred. [ka] In the compound represented by the above general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility. [ka] In the compound represented by the general formula (F-2), Y is H or CmF 2m+1 where m is an integer from 1 to 6, or CH2CH(OH)CH2-CmF 2m+1 where m is an integer between 4 and 6, or Cp H 2p+1 where p is an integer from 1 to 19, n is an integer from 1 to 6, and a is an integer from 4 to 14.

[0044] The fluorine-based surfactant may be a commercially available product, such as Surflon S-242, S-243, S-420, and S-431 (all manufactured by AGC Seimi Chemical Co., Ltd.), Megafac F-251, F-430, F-444, F-477, F-552, F-553, and F-554 (all manufactured by DIC Corporation), or CAPSTONE FS-10, FS-30, FS-31, FS-34, FS-35, FS-51, FS-60, FS-61, FS-63, FS-64, FS-65, FS-3100 (all manufactured by DuPont); Ftergent 212M, Ftergent 215M, Ftergent 250, Ftergent 251, Ftergent 222F, Ftergent 245F (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N (manufactured by Kitamura Chemical Industries Co., Ltd.), and the like are preferred. Among these, CAPSTONE FS-3100 and CAPSTON FS-3100 manufactured by Chemours are preferred because they provide good print quality, particularly significant improvements in color development, paper penetration, wetting, and dye uniformity. FS-34, Ftergent 250 and Ftergent 251 manufactured by Neos Co., Ltd., and Polyfox PF-151N manufactured by Kitamura Chemical Industries Co., Ltd. are particularly preferred.

[0045] Furthermore, commercially available products can be used as the acetylene glycol surfactant and the acetylene alcohol surfactant. Examples of commercially available products include Surfynol 104E, Surfynol 420, Surfynol 440, Surfynol 465, Surfynol SE, Surfynol SE-F, Surfynol PSA-336, Surfynol DF110D, Surfynol DF58, Olfine E1004, Olfine E1010, Olfine E1020, Olfine PD-001, Olfine PD-002W, Olfine PD-004, Olfine PD-005, Olfine EXP. 4001, Olfine EXP. 4200, Olfine EXP. 4123, and Olfine EXP. 4300 (all manufactured by Nissin Chemical Industry Co., Ltd.).

[0046] The content of the surfactant in the ink is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of providing excellent wettability and ejection stability and improving image quality, the content is preferably from 0.001% by mass to 5% by mass, and more preferably from 0.05% by mass to 5% by mass.

[0047] -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.

[0048] -Preservative and fungicidal agent- The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

[0049] -Rust inhibitor- The rust inhibitor is not particularly limited, and examples thereof include acid sulfites and sodium thiosulfate.

[0050] - pH adjuster - There are no particular limitations on the pH adjuster, provided that it is capable of adjusting the pH to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

[0051] The physical properties of the ink are not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are within the following ranges. The ink viscosity 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, viscosity can be measured using, for example, a rotational viscometer (RE85L 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 surface tension of the ink is preferably 35 mN / m or less, and more preferably 32 mN / m or less at 25° C., in order to ensure that the ink is properly leveled on the recording medium and the drying time of the ink is shortened. The pH of the ink is preferably 7 to 12, and more preferably 8 to 11, from the viewpoint of preventing corrosion of metal members that come into contact with the ink.

[0052] (Storage modulus of hollow resin particles and fixing resin) The ink of the present invention has a storage modulus at 25°C of the hollow resin particles (hereinafter also referred to as G1) and a storage modulus at 25°C of the fixing resin (hereinafter also referred to as G2) of 1.0 × 10 9 Pa or less, 4.0 × 10 7 The difference between G1 and G2 is preferably 1.0×10 Pa or less. 9 By ensuring that the viscosity is equal to or less than 1 Pa, an ink capable of forming printed matter with improved fastness and texture can be obtained. The storage modulus of the hollow resin particles and the fixing resin can be measured, for example, using a dynamic viscoelasticity measuring device ARES-G2 (manufactured by TA Instruments).

[0053] (Storage modulus of dried ink film) The ink of the present invention is dried to remove water and organic solvent, thereby obtaining a dried ink film. By forming the dried ink film, the storage modulus can be measured in the same manner as for the hollow resin particles and the fixing resin. The ink of the present invention has a storage modulus at 25°C of 1.0 x 10 (hereinafter also referred to as G3) of the dried ink film obtained by drying the ink. 6 Pa or more 1.0×10 8 Pa or less. G3 is 1.0×10 6 When the G3 is 1.0×10 Pa or more, a printed matter having good dry rub fastness and wet rub fastness can be obtained. 8 When the G3 is 1.0×10 Pa or less, a printed matter with a good texture can be obtained. 6 Pa or more 1.0×10 8 By ensuring that the viscosity is equal to or less than 1 Pa, it is possible to obtain printed matter that has the necessary mechanical strength and flexibility, and that also has excellent washing fastness.

[0054] (Pretreatment liquid) The pretreatment liquid contains a flocculant, an organic solvent, and water, and may also contain surfactants, antifoaming agents, pH adjusters, antiseptics, antifungals, rust inhibitors, and the like, as required. The organic solvent, surfactant, antifoaming agent, pH adjuster, antiseptic / fungal agent, and antirust agent may be the same as those used in ink, and other materials used in known treatment liquids may also be used. The type of flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, and polyvalent metal salts.

[0055] (Post-processing liquid) The post-treatment liquid is not particularly limited as long as it can form a transparent layer. The post-treatment liquid can be obtained by selecting and mixing organic solvents, water, resins, surfactants, antifoaming agents, pH adjusters, antiseptic and antifungal agents, anti-rust agents, etc. as needed. The post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

[0056] (Recording medium) The recording medium used for printing is not particularly limited as long as it is a fabric, and examples of fabric media include cotton media, polyester media, cotton-polyester blend media, wool media, and other blend media.

[0057] (ink container) The ink container of the present invention contains the ink of the present invention in a container, and may further contain other members appropriately selected as necessary. The container is not particularly limited, and its shape, structure, size, material, etc. can be appropriately selected depending on the purpose. For example, a container having at least an ink bag formed from an aluminum laminate film, a resin film, etc. is preferred.

[0058] <Printing device, printing method> The ink of the present invention can be suitably used in various recording devices using the ink jet recording method, such as printers, facsimile machines, copying machines, printer / fax / copier combination machines, and three-dimensional modeling devices. In the present invention, the term "printing device" and "printing method" refer to a device capable of ejecting ink or various treatment liquids onto a recording medium, and a method of recording using the device. The term "recording medium" refers to any material to which ink or various treatment liquids can be attached, even temporarily. The printing device of the present invention has the ink storage container of the present invention and an ejection head for ejecting ink. This printing device can include not only the head portion that ejects ink, but also means related to feeding, transporting, and discharging the recording medium, as well as other devices called pre-processing devices and post-processing devices. The printing apparatus and printing method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and drying means include, for example, means for heating and drying the printed surface and back surface of the recording medium. The heating means and drying means are not particularly limited, but for example, a hot air heater or an infrared heater can be used. Heating and drying can be performed before, during, or after printing. Furthermore, the printing device and printing method are not limited to those that visualize meaningful images such as letters and figures using ink. For example, they also include those that form patterns such as geometric designs and those that create three-dimensional images. Furthermore, unless otherwise specified, the printing device includes both a serial type device in which the ejection head moves and a line type device in which the ejection head does not move. Furthermore, this printing device includes not only desktop types, but also wide-width printing devices that can print on A0-sized recording media, and continuous feed printers that can use continuous paper wound into a roll as a recording medium, for example.

[0059] An example of a printing device will be described with reference to FIGS. 1 and 2. The case where cyan (C), magenta (M), and yellow (Y) color inks are used will be explained, but the ink of the present invention is a white ink, and an ink layer is formed by printing using the white ink before the black (K), cyan (C), magenta (M), and yellow (Y) color inks in the same manner as the color inks. FIG. 1 is a perspective view of the device. FIG. 2 is a perspective view of a main tank. An image forming device 400, which is an example of a printing device, is a serial-type image forming device. A mechanism unit 420 is provided within an exterior 401 of the image forming device 400. For example, each ink storage unit 411 of the main tanks 410 (410k, 410c, 410m, 410y) for each color, such as black (K), cyan (C), magenta (M), and yellow (Y), is formed from a packaging material such as aluminum laminate film. The ink storage unit 411 is housed in a storage container case 414 made of, for example, plastic. As a result, the main tanks 410 are used as ink cartridges for each color. On the other hand, a cartridge holder 404 is provided at the back side of the opening when the cover 401c of the apparatus main body is opened. A main tank 410 is detachably attached to the cartridge holder 404. This allows each ink outlet 413 of the main tank 410 to communicate with the ejection head 434 for each color via the supply tube 436 for each color, making it possible to eject ink from the ejection head 434 onto a recording medium. Furthermore, the main tank 410 for each color or each ink storage section 411 may be filled with a pre-treatment liquid or a post-treatment liquid instead of ink, and the liquid may be ejected from the ejection head 434 onto a recording medium.

[0060] This printing device can include not only a part that ejects ink, but also devices called pre-processing devices and post-processing devices. As an embodiment of the pre-treatment device and the post-treatment device, a liquid storage section containing a pre-treatment liquid or a post-treatment liquid and a liquid ejection head are added, as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y), and the pre-treatment liquid or the post-treatment liquid is ejected by an inkjet recording method. Other embodiments of the pre-treatment device and post-treatment device include those using a method other than the inkjet recording method, such as a blade coating method, a roll coating method, or a spray coating method.

[0061] The ink can be used in a wide variety of methods, including, but not limited to, inkjet recording, blade coating, gravure coating, bar coating, roll coating, dip coating, curtain coating, slide coating, die coating, and spray coating.

[0062] The use of the ink of the present invention is not particularly limited and can be appropriately selected depending on the purpose, and can be applied to, for example, printed matter, paint, coating material, base, etc. Furthermore, in addition to being used as an ink to form two-dimensional characters and images, the ink can also be used as a material for three-dimensional modeling to form three-dimensional solid images (three-dimensional models). A known three-dimensional modeling apparatus for forming a three-dimensional object can be used, and is not particularly limited. For example, an apparatus equipped with ink storage means, supply means, discharge means, drying means, etc. can be used. Three-dimensional models include three-dimensional models obtained by applying ink multiple times. Also included are molded products obtained by processing a structure on a substrate such as a recording medium to which ink has been applied. The molded products are, for example, records or structures formed in a sheet or film form that have been subjected to molding processes such as heat stretching or punching, and are suitable for use in applications where the surface is decorated and then molded, such as meters and operation panel panels for automobiles, office automation equipment, electrical and electronic devices, cameras, etc.

[0063] (Recorded material) The ink recorded matter of the present invention comprises an image formed on a recording medium using the ink of the present invention. Recording can be performed using an inkjet recording apparatus and an inkjet recording method to produce a recorded product.

[0064] In addition, in the present invention, the terms image formation, recording, printing, printing, etc. are all synonymous.

[0065] Recording medium, media, and printed material are all synonymous terms.

[0066] Examples of qualitative and quantitative methods for the organic solvents, resins, colorants, and other components contained in the ink include gas chromatography-mass spectrometry (GC-MS). Examples of measurement devices using gas chromatography-mass spectrometry (GC-MS) include the GCMS-QP2020NX (manufactured by Shimadzu Corporation). Furthermore, water contained in the ink can be measured by general methods such as quantifying volatile components using gas chromatography-mass spectrometry (GC-MS) or by measuring mass fluctuations using thermogravimetry-differential thermal analysis (TG-DTA). [Example]

[0067] Examples of the present invention will be described below, but the present invention is not limited to these examples. In the examples, "parts" means "parts by mass" unless otherwise specified. Unless otherwise specified, ink preparation and evaluation were carried out at 25°C and a humidity of 60%.

[0068] (Production example of hollow resin particles 1) <Preparation of seed particle emulsion 1> A four-neck separable flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with deionized water (726.0 parts), methyl methacrylate (5.0 parts), and methacrylic acid (0.1 parts) and heated with stirring. When the internal temperature of the separable flask reached 70°C, 10% aqueous ammonium persulfate solution (1.0 parts) was added and the mixture was heated at 80°C for 20 minutes. Meanwhile, methyl methacrylate (141.0 parts), methacrylic acid (94.9 parts), an anionic emulsifier, sodium alkylbenzenesulfonate (5.0 parts: Neogen SF-20 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and deionized water (120.0 parts) were emulsified using a homodisper to form a pre-emulsion, which was then added to the dropping funnel. Next, while maintaining the internal temperature of the separable flask at 80°C, the pre-emulsion obtained above was added dropwise uniformly over 3 hours, and simultaneously, a 10% aqueous ammonium persulfate solution (10.0 parts) was added dropwise uniformly over 3 hours. After completion of the addition, the mixture was aged at 80°C for 3 hours, cooled, and then filtered using a 120-mesh filter cloth to obtain seed particle emulsion 1.

[0069] <Preparation of hollow resin particles 1> -First stage polymerization- A four-neck separable flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with deionized water (188.2 parts), and the seed particle emulsion 1 (66.0 parts) obtained above was added dropwise. The mixture was heated to 80°C with stirring. Meanwhile, butyl acrylate (2.4 parts), butyl methacrylate (1.1 parts), methyl methacrylate (19.5 parts), methacrylic acid (0.7 parts), sodium alkylbenzenesulfonate (5.0 parts: Neogen SF-20 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and deionized water (55.3 parts) were emulsified with a homodisper to form pre-emulsion 1, which was then placed in the dropping funnel. Then, while maintaining the internal temperature of the separable flask at 80°C, the pre-emulsion 1 obtained above was added dropwise uniformly over 30 minutes, and simultaneously, a 10% aqueous sodium persulfate solution (1.2 parts) was added dropwise uniformly over 30 minutes.

[0070] -Second-stage polymerization- Styrene (5.0 parts), sodium alkylbenzenesulfonate (5.0 parts: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and deionized water (126.8 parts) were emulsified using a homodisper to form pre-emulsion 2, which was then poured into a dropping funnel. Then, while maintaining the internal temperature of the separable flask at 80°C, one hour after the completion of the dropwise addition of pre-emulsion 1, the pre-emulsion 2 obtained above was added dropwise uniformly over 60 minutes. Simultaneously, a 10% aqueous solution of sodium persulfate (3.5 parts) was added dropwise uniformly over 60 minutes. After the completion of the dropwise addition of pre-emulsion 2, 28% aqueous ammonia (7.5 parts) was added dropwise to swell and dissolve the seed particles, and the mixture was aged at 80°C for one hour. After cooling, the mixture was filtered using a 120-mesh filter cloth to obtain hollow resin particles 1 as an emulsion. The solids content of the resulting emulsion was adjusted to 15 parts by mass.

[0071] (Production Example of Hollow Resin Particles 2) In the manufacturing example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 10 parts, and when mixing styrene, sodium alkylbenzene sulfonate, and deionized water, 1 part of ethylene glycol dimethacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a crosslinking agent. Hollow resin particles 2 were obtained as an emulsion by carrying out the same manufacturing method as above.

[0072] (Production Example of Hollow Resin Particles 3) In the production example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 15 parts, and 1 part of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzenesulfonate, and deionized water. The rest of the production process was the same as above, and hollow resin particles 3 were obtained as an emulsion.

[0073] (Production Example of Hollow Resin Particles 4) Hollow resin particles 4 were obtained as an emulsion by carrying out the same production method as in the production example of hollow resin particles 1, except that the amount of styrene added in the second polymerization step was changed to 20 parts.

[0074] (Production Example of Hollow Resin Particles 5) Hollow Resin Particles 5 were obtained as an emulsion by carrying out the same production method as in the production example of Hollow Resin Particles 1, except that the amount of styrene added in the second polymerization step was changed to 45 parts.

[0075] (Production Example of Hollow Resin Particles 6) Hollow resin particles 6 were obtained as an emulsion by carrying out the same production method as in the production example of hollow resin particles 1, except that the amount of styrene added in the second polymerization step was changed to 65 parts.

[0076] (Production Example of Hollow Resin Particles 7) Hollow Resin Particles 7 were obtained as an emulsion by carrying out the same production method as in the production example of Hollow Resin Particles 1, except that the amount of styrene added in the second polymerization step was changed to 75 parts.

[0077] (Production Example of Hollow Resin Particles 8) Hollow resin particles 8 were obtained as an emulsion by carrying out the same production method as in the production example of hollow resin particles 1, except that the amount of styrene added in the second polymerization step was changed to 80 parts.

[0078] (Production Example of Hollow Resin Particles 9) Hollow Resin Particles 9 were obtained as an emulsion by carrying out the same production method as in the production example of Hollow Resin Particles 1, except that the amount of styrene added in the second polymerization step was changed to 85 parts.

[0079] (Production Example of Hollow Resin Particles 10) In the manufacturing example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 85 parts, and 1 part of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzene sulfonate, and deionized water. The rest of the manufacturing process was the same as in the manufacturing example of hollow resin particles 1, and hollow resin particles 10 were obtained as an emulsion.

[0080] (Production Example of Hollow Resin Particles 11) In the production example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 80 parts, and 5 parts of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzenesulfonate, and deionized water. The rest of the production process was the same as in the production example of hollow resin particles 1, and hollow resin particles 11 were obtained as an emulsion.

[0081] (Production Example of Hollow Resin Particles 12) In the production example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 85 parts, and 5 parts of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzene sulfonate, and deionized water. The rest of the production process was the same as in the production example of hollow resin particles 1, but hollow resin particles 12 were obtained as an emulsion.

[0082] (Production example of hollow resin particles 13) In the production example of hollow resin particles 1, the amount of styrene added in the second-stage polymerization was changed to 10 parts, and further, 5 parts of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzenesulfonate, and deionized water. By performing the same production method as above, hollow resin particles 13 were obtained as an emulsion.

[0083] (Production Example of Hollow Resin Particles 14) In the production example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 15 parts, and 3 parts of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzene sulfonate, and deionized water. The rest of the production process was the same as in the production example of hollow resin particles 1, but hollow resin particles 14 were obtained as an emulsion.

[0084] (Production example of hollow resin particles 15) In the production example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 15 parts, and 5 parts of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzene sulfonate, and deionized water. The rest of the production process was the same as in the production example of hollow resin particles 1, and hollow resin particles 15 were obtained as an emulsion.

[0085] (Production example of hollow resin particles 16) In the production example of hollow resin particles 1, the amount of styrene added in the second polymerization step was changed to 8 parts, and 7 parts of ethylene glycol dimethacrylate was added as a crosslinking agent when mixing styrene, sodium alkylbenzene sulfonate, and deionized water. The rest of the production process was the same as in the production example of hollow resin particles 1, and hollow resin particles 16 were obtained as an emulsion.

[0086] (Example of manufacturing hollow inorganic particles) Hollow inorganic particles were produced by the same method as that described in JP 2020-121528 A. Details are shown below.

[0087] <Preparation of Silica-Coated Particles A> 1.3 parts by weight of non-crosslinked styrene-acrylic resin particle aqueous dispersion FS201E (non-crosslinked styrene-acrylic resin particle aqueous dispersion, solids content 27% by weight, Nippon Paint Co., Ltd.) and 98.7 parts by weight of water were thoroughly dispersed using an ultrasonic homogenizer (Nippon Seiki Co., Ltd., US-300T, tip diameter 7 mm, 100 μA, 10 minutes). The mixture was then transferred to a plastic container and stirred. A few drops of 1N aqueous sodium hydroxide solution (Wako Pure Chemical Industries, Ltd.) were added dropwise to adjust the pH to 10.5. Next, 1.0 parts by weight of 3-aminopropylethoxysilane (APTES, Tokyo Chemical Industry Co., Ltd.) and 1.2 parts by weight of tetraethoxysilane (TEOS, Tokyo Chemical Industry Co., Ltd.) were slowly added dropwise in this order and allowed to react at 25°C for 20 hours. A silica shell was formed on the resin particle surface via a sol-gel reaction, yielding silica-coated particles A.

[0088] <Preparation of hollow inorganic particles A> Next, the obtained silica-coated particles A were washed with water and centrifuged to obtain a wet cake of silica-coated particles A. Furthermore, tetrahydrofurone was added to dissolve the core material resin particles, and the mixture was stirred for 1 hour, then washed with water, dispersed again in water, and concentrated to obtain [aqueous phase of 18% by mass of hollow inorganic particles A]. In both washing steps, the silica-coated particles A or hollow inorganic particles A were subjected to liquid-liquid replacement because drying could cause aggregation. To 100 parts by mass of the [18% by mass aqueous phase of hollow inorganic particles A], 6 parts by mass of an amino group-containing copolymer (dispersant, manufactured by BYK Japan, product name "Disperbyk-190" (active ingredient 100% by mass)) and 12 parts by mass of water were added and thoroughly stirred, and then dispersed using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., US-300T, tip diameter 7 mm, 100 μA, 30 minutes). Coarse particles from the resulting emulsion were removed using centrifugation (4000 rpm, 1 minute), and the resulting emulsion was filtered using a membrane filter (cellulose acetate membrane) with an average pore size of 5 μm, yielding hollow inorganic particles A as an emulsion. The solids content of the resulting emulsion was adjusted to 15 parts by mass.

[0089] <Preparation of Silica-Coated Particles B> 2.4 parts by weight of non-crosslinked styrene-acrylic resin particle aqueous dispersion FS301E (non-crosslinked styrene-acrylic resin particle aqueous dispersion, solids content 27% by weight, Nippon Paint Co., Ltd.) and 97.6 parts by weight of water were thoroughly dispersed using an ultrasonic homogenizer (Nippon Seiki Co., Ltd., US-300T, tip diameter 7 mm, 100 μA, 10 minutes). The mixture was then transferred to a plastic container and stirred. A few drops of 1N aqueous sodium hydroxide solution (Wako Pure Chemical Industries, Ltd.) were added dropwise to adjust the pH to 10.5. Next, 1.0 part by weight of 3-aminopropylmethoxysilane (APTMS, Tokyo Chemical Industry Co., Ltd.) and 1.0 part by weight of tetramethoxysilane (TMOS, Tokyo Chemical Industry Co., Ltd.) were slowly added dropwise and reacted at 25°C for 10 hours. Silica shells were formed on the resin particle surfaces via a sol-gel reaction, yielding silica-coated particles B.

[0090] <Preparation of hollow inorganic particles B> Next, the obtained silica-coated particles B were washed with water and centrifuged to obtain a wet cake of silica-coated particles B. Furthermore, tetrahydrofurone was added to dissolve the resin particles of the core material, and the mixture was stirred for 1 hour, washed with water, dispersed again in water, and concentrated to obtain an [aqueous phase of 18% by mass of hollow inorganic particles B]. In both washing steps, the silica-coated particles B or hollow inorganic particles B were subjected to liquid-liquid replacement because drying could cause aggregation. To 100 parts by mass of the [18% by mass aqueous phase of hollow inorganic particles B], 6 parts by mass of an amino group-containing copolymer (dispersant, manufactured by BYK Japan, product name "Disperbyk-190" (active ingredient 100% by mass)) and 12 parts by mass of water were added and thoroughly stirred, and then dispersed using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., US-300T, tip diameter 7 mm, 100 μA, 30 minutes). Coarse particles from the resulting emulsion were removed using centrifugation (4000 rpm, 1 minute), and the resulting emulsion was further filtered using a membrane filter (cellulose acetate membrane) with an average pore size of 5 μm, yielding hollow inorganic particles B as an emulsion. The solids content of the resulting emulsion was adjusted to 15 parts by mass.

[0091] (Measurement of the primary particle diameter, shell thickness, and hollow diameter R of hollow particles) The particles in the ink were observed with a transmission electron microscope (manufactured by JEOL Ltd., "JEM-2100F"), and the primary particle diameter, shell thickness, and hollow diameter R were measured from the obtained TEM images according to FIG. 3.

[0092] <Hollow diameter> In the present invention, the hollow diameter refers to the diameter of the hollow pore portion of the hollow particles. That is, as shown in (1) of FIG. 3, it means the length obtained by subtracting the shell thickness from the primary particle diameter. In the present invention, the measurement of the hollow diameter is performed using a TEM image obtained by observing the particles in the ink with a transmission electron microscope (manufactured by JEOL Ltd., "JEM-2100F") or a SEM image obtained by observing the printed layer of the printed matter with a heated cathode field emission scanning microscope (Schottky, FE-SEM, ULTRA55 manufactured by Carl Zeiss). Since these observation images are two-dimensional images, the spherical hollow pore portion is observed as a circle. At that time, as shown in (1) of FIG. 3, the hollow diameter is assumed to be the diameter of the observed circle. Also, as shown in FIG. 3(2) and FIG. 3(3), the observed hollow pore portion may not be a perfect circle but may be observed as an ellipse or a hollow particle with a distorted shape. In that case, the longest diameter of the figure is defined as the hollow diameter R.

[0093] (Measurement of the storage modulus of hollow resin particles) The emulsion of hollow resin particles was dried in a 60°C dryer for 3 hours, and 0.2 g of the obtained powder was compression-molded using a tablet press machine (tablet diameter 7 mm, manufactured by Systems Engineering Co., Ltd.) to obtain a tablet-shaped hollow resin sample. The storage modulus G1 of this sample was measured at 25°C using a dynamic viscoelasticity measuring device ARES-G2 (manufactured by TA Instruments). (Measurement conditions of ARES-G2) · Temperature: 25°C (room temperature) · Frequency: 1 Hz · Measurement method: Tortion · Axial force: 10.0 g ·Initial strain: 0.1%

[0094] Table 1 shows the primary particle diameter, shell thickness, hollow diameter R, shell thickness / primary particle diameter, and storage modulus G1 at 25°C for each hollow particle.

[0095] [Table 1]

[0096] (Example of fixing resin manufacturing) <Production example of urethane resin 1> -Synthesis of polyester polyol 1- While introducing nitrogen, 407 g of BA-2 (ethylene oxide adduct of bisphenol A; manufactured by Nippon Nyukazai Co., Ltd.) and 73 g of dimethyl adipate were charged into a 0.5 L separable flask and melted at 130°C. Once melted, 0.14 g of titanium tetraisopropoxide was added, and the mixture was heated to 230°C over 3 to 4 hours with stirring, and reacted at 230°C for an additional 2 to 3 hours. Subsequently, 0.07 g of titanium tetraisopropoxide was added and maintained for 2 hours, after which the introduction of nitrogen was stopped and the mixture was reacted for an additional 2 hours under reduced pressure of 1 kPa, to obtain polyester polyol 1.

[0097] -Synthesis of urethane resin 1- A 0.5 L separable flask equipped with a stirring blade, thermometer, and reflux condenser was charged with 100 g of [Polyester Polyol 1], 5.4 g of 2,2-bis(hydroxymethyl)propionic acid, 4.1 g of triethylamine, and 78 g of acetone while introducing nitrogen. The mixture was heated to 40 °C to dissolve the raw materials. Next, 35 g of isophorone diisocyanate and one drop of tin(II) 2-ethylhexanoate were added, and the mixture was heated to 80 °C and reacted for 4 hours. The temperature was then lowered to 40 °C, and 268 g of water was added to form microparticles. 2.3 g of diethylenetriamine was added and reacted for 4 hours. Finally, the acetone was removed to obtain Urethane Resin 1 as an emulsion. The solids concentration was 32 parts by mass, and the storage modulus G2 at 25 °C was 9.0 × 10 5 It was Pa.

[0098] <Production example of urethane resin 2> -Synthesis of polyester polyol 2- While introducing nitrogen, 323 g of BA-2 (ethylene oxide adduct of bisphenol A; manufactured by Nippon Nyukazai Co., Ltd.), 14.8 g of trimethylolpropane, and 143 g of dimethyl isophthalate were charged into a 0.5 L separable flask and melted at 130°C. Once melted, 0.14 g of titanium tetraisopropoxide was added, and the mixture was heated to 230°C over 3 to 4 hours with stirring, and reacted at 230°C for an additional 2 to 3 hours. Subsequently, 0.07 g of titanium tetraisopropoxide was added and maintained for 2 hours. After that, the nitrogen introduction was stopped, and the mixture was reacted for an additional 2 hours under a reduced pressure of 1 kPa, to obtain polyester polyol 2.

[0099] -Synthesis of urethane resin 2- A 0.5 L separable flask equipped with a stirring blade, thermometer, and reflux condenser was charged with 100 g of [Polyester Polyol 2], 5.7 g of 2,2-bis(hydroxymethyl)propionic acid, 4.3 g of triethylamine, and 79 g of acetone while introducing nitrogen. The mixture was heated to 40 °C to dissolve the raw materials. Next, 37 g of isophorone diisocyanate and one drop of tin(II) 2-ethylhexanoate were added, and the mixture was heated to 80 °C and reacted for 4 hours. The temperature was then lowered to 40 °C, and 273 g of water was added to form microparticles. 2.2 g of diethylenetriamine was added and reacted for 4 hours. Finally, the acetone was removed to obtain Urethane Resin 2 as an emulsion. The solids concentration was 31 parts by mass, and the storage modulus G2 at 25 °C was 2.5 × 10 6 It was Pa.

[0100] <Production example of urethane resin 3> -Synthesis of polyester polyol 3- While introducing nitrogen, 343 g of BA-2 (ethylene oxide adduct of bisphenol A; manufactured by Nippon Nyukazai Co., Ltd.) and 137 g of dimethyl isophthalate were charged into a 0.5 L separable flask and melted at 130°C. Once melted, 0.14 g of titanium tetraisopropoxide was added, and the mixture was heated to 230°C over 3 to 4 hours with stirring, and reacted at 230°C for an additional 2 to 3 hours. Subsequently, 0.07 g of titanium tetraisopropoxide was added and maintained for 2 hours, after which the introduction of nitrogen was stopped and the mixture was reacted for an additional 2 hours under reduced pressure of 1 kPa, yielding polyester polyol 3.

[0101] -Synthesis of urethane resin 3- A 0.5 L separable flask equipped with a stirring blade, thermometer, and reflux condenser was charged with 100 g of [Polyester Polyol 3], 5.4 g of 2,2-bis(hydroxymethyl)propionic acid (2,2-dimethylolpropionic acid), 4.1 g of triethylamine, and 78 g of acetone while introducing nitrogen. The mixture was heated to 40 °C to dissolve the raw materials. Next, 35 g of isophorone diisocyanate and one drop of tin(II) 2-ethylhexanoate were added, and the mixture was heated to 80 °C and reacted for 4 hours. The temperature was then lowered to 40 °C, and 268 g of water was added to form microparticles. 2.3 g of diethylenetriamine was added and reacted for 4 hours. Finally, the acetone was removed to obtain Urethane Resin 3 as an emulsion. The solids concentration was 32 parts by mass, and the storage modulus G2 at 25 °C was 5.1 × 10 6 It was Pa.

[0102] <Production example of urethane resin 4> -Synthesis of polyester polyol 4- Into a 0.5 L separable flask, while introducing nitrogen, 343 g of BA-2 (ethylene oxide adduct of bisphenol A; manufactured by Nippon Emulsion Co., Ltd.) and 137 g of dimethyl terephthalate were charged and melted at 130°C. When these were melted, 0.14 g of titanium tetraisopropoxide was added, and the temperature was raised to 230°C over 3 - 4 hours while stirring, and the reaction was carried out at 230°C for another 2 - 3 hours. Then, 0.07 g of titanium tetraisopropoxide was added and held for 2 hours, after which the introduction of nitrogen was stopped, and the reaction was further carried out under a reduced pressure of 1 kPa for 2 hours to obtain polyester polyol 4.

[0103] - Synthesis of urethane resin 4 - Into a 0.5 L separable flask equipped with a stirring blade, thermometer, and reflux tube, while introducing nitrogen, 100 g of polyester polyol 4, 5.5 g of 2,2-bis(hydroxymethyl)propionic acid, 4.1 g of triethylamine, and 78 g of acetone were charged, and heated to 40°C to dissolve the raw materials. Next, 35 g of isophorone diisocyanate and 1 drop of tin(II) 2-ethylhexanoate were added, the temperature was raised to 80°C, and the reaction was carried out for 4 hours. Then, the temperature was lowered to 40°C, 269 g of water was added to atomize, and further 2.3 g of diethylenetriamine was added, and the reaction was carried out for 4 hours. Finally, by removing acetone, urethane resin 4 was obtained as an emulsion. The solid content concentration was 32 parts by mass, and the storage modulus G2 at 25°C was 6.1×10 6 Pa.

[0104] (Measurement of storage modulus of fixing resin) The emulsion of the fixing resin was dried in a 60°C dryer for 3 hours to obtain a dried film. This resin film sample was cut into a size of 30 mm in length and 10 mm in width, and the storage modulus G2 was measured under the condition of 25°C using a dynamic viscoelasticity measuring device ARES-G2 (manufactured by TA Instruments). <Measurement conditions of ARES-G2> · Temperature: 25°C (room temperature) · Frequency: 1 Hz · Measurement method: Tension · Axial force: 10.0 g · Initial distortion: 0.1%

[0105] (Production example of Ink 1) 11.5 parts by mass of 1,2-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.5 parts by mass of 3-methoxy-3-methylbutanol (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.3 parts by mass of 2-ethyl-1,3-hexanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), 8 parts by mass of an emulsion of urethane resin 2 as a resin in terms of solid content, 0.4 parts by mass of a silicone surfactant (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-640) as a surfactant, 0.1 parts by mass of 2-amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) as a pH adjuster, and ion-exchanged water (a total of 69.2 parts by mass including the water contained in the emulsion of urethane resin 2 and the emulsion of hollow resin particles 3 described later) were stirred for 1 hour and uniformly mixed. Next, 8 parts by mass of an emulsion of hollow resin particles 3 was added as a pigment solid content, and the mixture was further stirred for 1 hour and uniformly mixed. Pressure filtration was performed using a membrane filter (cellulose acetate membrane) with an average pore size of 5 μm to remove coarse particles and dust, and Ink 1 was prepared.

[0106] (Production examples of Inks 2 to 21) Inks 2 to 21 were prepared in the same manner as in the production example of Ink 1, except that the combination of hollow particles and fixing resin was changed as shown in Table 2.

[0107] (Measurement of storage elastic modulus of ink dry film) Inks 1 to 21 were dried in a 60 °C dryer for 3 hours to obtain ink dry films. Samples of these ink dry films were cut out to a size of 30 mm in length and 10 mm in width, and the storage elastic modulus G3 of these samples was measured under the condition of 25 °C using a dynamic viscoelasticity measuring device ARES-G2 (manufactured by TA Instruments). <Measurement conditions of ARES-G2> · Temperature: 25 °C (room temperature) · Frequency: 1 Hz · Measurement method: Tension · Axial force: 10.0 g ·Initial strain: 0.1%

[0108] Table 2 shows the combinations of hollow particles and fixing resins for each ink, and the results of measuring the storage modulus G3 at 25°C of the dried ink film.

[0109] [Table 2]

[0110] (Image formation) Example 1 An inkjet printer (device name: Ri100, manufactured by Ricoh Co., Ltd.) was filled with ink 1. An image was further printed on cotton media (cotton broadcloth, unmercerized, manufactured by Shikisen Co., Ltd.) using the inkjet printer filled with ink 1. The resulting print was then heated and dried for 5 minutes in a thermostatic chamber set at 100°C. Through these operations, a print of Example 1 was obtained. Note that the present invention is not limited to the above-mentioned inkjet printer, and other types of inkjet printers can be used as appropriate.

[0111] <Examples 2 to 12 and Comparative Examples 1 to 9> Printed materials of Examples 2 to 12 and Comparative Examples 1 to 9 were obtained by carrying out the same procedure as in Example 1, except that Ink 1 was replaced with Inks 2 to 21.

[0112] The prints obtained in Examples 1 to 12 and Comparative Examples 1 to 9 were evaluated for dry rub fastness, wet rub fastness, wash fastness, and texture. The results are shown in Tables 3 to 5.

[0113] [Table 3]

[0114] [Table 4]

[0115] [Table 5]

[0116] (Evaluation method) <Dry rub fastness> The print sample was cut into a piece of 2 cm x 15 cm and placed as an evaluation sample in a Gakushin tester (a dyed material rubbing fastness tester, manufactured by Intec Co., Ltd.). Then, a transfer cloth (Kanakin No. 3) was attached to a weight and rubbed 100 times in accordance with the JIS standard "JIS L 0849 Test method for color fastness to rubbing." The resulting transferred portion onto the transfer fabric was graded according to the JIS standard "JIS L 0801 General rules for testing color fastness." The grade results were classified into the following evaluation ranks. -Evaluation Rank- Rank A: Grade 4.5 or above Rank B: Grade 3 or above, less than 4.5 Rank C: Grade 2.5 or above, less than grade 3 Rank D: Less than 2.5 grade

[0117] <Wet rubbing fastness evaluation> The transfer fabric was soaked in ion-exchanged water in an amount equal to the fabric's own weight beforehand. Using this transfer fabric soaked in ion-exchanged water, it was rubbed 100 times back and forth according to the JIS standard "JIS L 0849 Test method for color fastness to rubbing" using the same procedure as in the evaluation of dry rubbing fastness. The resulting transferred portion onto the transfer fabric was graded according to the JIS standard "JIS L 0801 General rules for testing color fastness." The grade results were classified into the following evaluation ranks. -Evaluation Rank- Rank A: Grade 4 or above Rank B: Grade 2.5 or above, less than grade 4 Rank C: Grade 2 or above, less than 2.5 Rank D: Less than Grade 2

[0118] <Washing fastness evaluation> The printed solid image was used as a sample for evaluating washing fastness. The washing fastness was evaluated according to the JIS standard "JIS L 0844 Test method for color fastness to washing." The resulting transferred portion onto the attached fabric was graded according to the JIS standard "JIS L 0801 General rules for testing color fastness." The grade results were classified into the following evaluation ranks. -Evaluation Rank- Rank A: Grade 4 or above Rank B: Grade 2.5 or above, less than grade 4 Rank C: Grade 2 or above, less than 2.5 Rank D: Less than Grade 2

[0119] <Texture evaluation> The printed image sample was cut into a size of 8.5 cm x 8.5 cm to prepare a sample for evaluating texture. The bending resistance was evaluated according to JIS L1096 E method. Evaluation machine: Hand-ometer (HOM-200, manufactured by Daiei Scientific Instruments Manufacturing Co., Ltd.) Sample size: 85mm x 85mm The difference in bending resistance between the unprinted media and the evaluation sample was calculated, and the evaluation was classified into the following ranks based on the difference. -Evaluation Rank- Rank A: Difference in stiffness is 0.0g or more and less than 15.0g Rank B: Difference in stiffness is 15.0g or more and less than 25.0g Rank C: Difference in stiffness is 25.0g or more and less than 40.0g Rank D: Difference in stiffness is 40.0g or more [Explanation of symbols]

[0120] 400 Image forming device 401 Exterior of image forming device 401c Device body cover 404 Cartridge Holder 410 Main Tank 410k, 410c, 410m, 410y Main tanks for black (K), cyan (C), magenta (M), and yellow (Y) 411 Ink storage unit 413 Ink outlet 414 Storage container case 420 Mechanism Department 434 Discharge Head 436 Supply Tube [Prior art documents] [Patent documents]

[0121] [Patent Document 1] Japanese Patent Application Publication No. 2017-088850 [Patent Document 2] Japanese Patent Publication No. 2022-152286

Claims

1. An ink containing hollow resin particles and a fixing resin, a difference between the storage modulus of the hollow resin particles at 25°C and the storage modulus of the fixing resin at 25°C is 1.0 × 10 Pa or less; The ink, characterized in that the storage modulus of a dried ink film obtained by drying the ink at 25°C is 1.0 x 106 Pa or more and 1.0 x 108 Pa or less.

2. 2. The ink according to claim 1, wherein the difference between the storage modulus at 25° C. of the hollow resin particles contained in the ink and the storage modulus at 25° C. of the fixing resin is 4.0×10 Pa or less.

3. 2. The ink according to claim 1, wherein the ratio of "shell thickness / primary particle diameter" of the hollow resin particles contained in the ink is 0.15 or less.

4. 2. The ink according to claim 1, wherein the ratio of "shell thickness / primary particle diameter" of the hollow resin particles contained in the ink is 0.10 or less.

5. An ink container comprising the ink according to any one of claims 1 to 4 contained therein.

6. A printing device comprising the ink container according to claim 5 and an ejection head for ejecting ink.

7. A printing method comprising forming an image on a recording medium using the ink according to any one of claims 1 to 4.

Images