Inkjet ink and image-recording method

Abstract

Provided are an inkjet ink and an application thereof, the inkjet ink containing a pigment, a wax, water, and a polyoxyalkylene alkyl ether having an HLB value of 10-20, wherein the wax has a melting point of 80-110°C; an organic solvent having a boiling point of 250°C or higher is not contained, or the contained amount of an organic solvent having a boiling point of 250°C or higher is 5 mass% or less with respect to the entirety of the inkjet ink; and the contained amount of the polyoxyalkylene alkyl ether having an HLB value of 10-20 is 0.1-2 mass% with respect to the entirety of the inkjet ink.

Description

Inkjet ink and image recording method

[0001] The present disclosure relates to inkjet inks and image recording methods.

[0002] Various studies have been conducted on inkjet inks. For example, Japanese Patent Application Laid-Open No. 2024-59573 describes an aqueous inkjet ink containing wax, a specific nonionic dispersant for dispersing the wax, and a specific anionic dispersant.

[0003] Incidentally, in inkjet inks, there are cases where improvements in the drying properties, abrasion resistance, and image quality of the recorded image are required while ensuring ejection properties.

[0004] An object of one aspect of the present disclosure is to provide an inkjet ink and an image recording method that can record images that are excellent in drying properties, scratch resistance, and image quality while ensuring ejection properties.

[0005] The present disclosure includes the following aspects. <1> An ink-jet ink comprising a pigment, a wax, a polyoxyalkylene alkyl ether having an HLB value of 10 to 20, and water, wherein the wax has a melting point of 80°C to 110°C, wherein the ink-jet ink does not contain an organic solvent having a boiling point of 250°C or higher, or the content of the organic solvent having a boiling point of 250°C or higher is 5% by mass or less relative to the total amount of the ink-jet ink, and wherein the content of the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 is 0.1% by mass to 2% by mass relative to the total amount of the ink-jet ink. <2> The ink-jet ink according to <1>, wherein the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 has an HLB value of 12 to 20. <3> The ink-jet ink according to <1> or <2>, wherein the content of the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 is 0.5% by mass to 2% by mass relative to the total amount of the ink-jet ink. <4> The ink-jet ink according to any one of <1> to <3>, further comprising resin particles, wherein T1 and T2 satisfy the following formula (A) where T1°C is the glass transition temperature of the resin particles and T2°C is the melting point of the wax: -30≦T2−T1≦50 (A) <5> The ink-jet ink according to any one of <1> to <4>, wherein W and R satisfy the following formula (B) where W is the content of the wax relative to the total amount of the ink-jet ink and R is the content of the resin particles relative to the total amount of the ink-jet ink: 0≦R−W≦4 (B) <6> The ink-jet ink according to any one of <1> to <5>, wherein the wax is at least one wax selected from the group consisting of paraffin wax and hydrocarbon wax. <7> The ink-jet ink according to any one of <1> to <6>, wherein the wax has an anionic group. <8> The ink-jet ink according to any one of <1> to <7>, wherein the wax is in the form of particles having an average particle size of 200 nm or less. <9> The ink-jet ink according to any one of <1> to <8>, wherein the content of the wax is 1% by mass to 4% by mass relative to the total amount of the ink-jet ink.<10> The ink-jet ink according to any one of <1> to <9>, which does not contain an organic solvent having a boiling point of 150° C. or more but less than 250° C., or the content of organic solvents having a boiling point of 150° C. or more but less than 250° C. is 21% by mass or less based on the total amount of the ink-jet ink. <11> An image recording method, which includes a step of applying the ink-jet ink according to any one of <1> to <10> onto a recording medium by an ink-jet recording method to record an image.

[0006] According to one aspect of the present disclosure, there are provided an inkjet ink and an image recording method that can record images that are excellent in drying properties, scratch resistance, and image quality while ensuring ejection properties.

[0007] In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0008] As used herein, the amount of each component in a composition refers to the total amount of the components in the composition unless otherwise specified, when the composition contains multiple substances corresponding to each component. In this specification, a combination of two or more preferred aspects is a more preferred aspect. As used herein, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0009] In this specification, the term "image" refers to a film in general, and "image recording" refers to the formation of an image (i.e., a film). The concept of "image" in this specification also includes a solid image.

[0010] In this specification, the term "(meth)acrylate" encompasses both acrylate and methacrylate, and the term "(meth)acrylic acid" encompasses both acrylic acid and methacrylic acid.

[0011] [Inkjet ink] The inkjet ink (hereinafter also simply referred to as "ink") of the present disclosure comprises a pigment, a wax, a polyoxyalkylene alkyl ether having an HLB value of 10 to 20, and water, wherein the wax has a melting point of 80°C to 110°C and does not contain an organic solvent having a boiling point of 250°C or higher, or the content of the organic solvent having a boiling point of 250°C or higher is 5% by mass or less relative to the total amount of the inkjet ink, and the content of the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 is 0.1% by mass to 2% by mass relative to the total amount of the inkjet ink. The ink of the present disclosure is an inkjet ink. In other words, the ink of the present disclosure is an ink used in a form that is ejected by an inkjet recording method.

[0012] The ink of the present disclosure can record images that are excellent in drying properties, scratch resistance, and image quality while ensuring ejection properties.

[0013] The reason for the above effects is presumed to be as follows: The ink of the present disclosure has a low content of organic solvents with a boiling point of 250°C or higher, and therefore has excellent drying properties. Generally, excellent drying properties tend to reduce jetting properties, making it difficult to achieve both dryness and jetting properties; however, the ink of the present disclosure ensures jetting properties by including a predetermined amount of polyoxyalkylene alkyl ether with an HLB value of 10 to 20. Furthermore, the ink of the present disclosure has excellent abrasion resistance and image quality by including a predetermined amount of wax with a specific melting point.

[0014] In contrast, the ink described in JP-A-2024-59573 contains a large amount of organic solvents with a boiling point of 250° C. or higher, and is presumed to have poor drying properties.

[0015] Each component contained in the ink of the present disclosure will be described below.

[0016] (Pigment) The ink of the present disclosure contains at least one pigment. The pigment may be an organic pigment or an inorganic pigment.

[0017] Examples of organic pigments include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments or polycyclic pigments are preferred. Examples of azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Examples of dye chelates include basic dye chelates and acid dye chelates.

[0018] Examples of inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black.

[0019] Examples of the pigment include those described in "Encyclopedia of Pigments" edited by Seijiro Ito (published in 2000), "Industrial Organic Pigments" by W. Herbst and K. Hunger, and JP-A Nos. 2002-12607, 2002-188025, 2003-26978, and 2003-342503.

[0020] The average particle size of the pigment is preferably 10 nm to 200 nm, more preferably 10 nm to 180 nm, and even more preferably 10 nm to 150 nm. When the average particle size is 200 nm or less, color reproducibility is improved and ink ejection properties are improved. Furthermore, when the average particle size is 10 nm or more, light resistance is improved.

[0021] The particle size distribution of the pigment is not particularly limited, and may be either a broad particle size distribution or a monodisperse particle size distribution. Two or more pigments having a monodisperse particle size distribution may be mixed and used.

[0022] The average particle size and particle size distribution of the pigment are measured using a particle size distribution measuring device (for example, Microtrac UPA (registered trademark) EX150 manufactured by Nikkiso Co., Ltd.).

[0023] The content of the pigment is preferably 1% by mass to 20% by mass, and more preferably 1.5% by mass to 10% by mass, based on the total amount of the ink.

[0024] (Wax) The ink of the present disclosure contains at least one wax. When the ink contains a wax, blocking resistance in a high-humidity environment is improved.

[0025] In the ink of the present disclosure, the melting point of the wax is 80°C to 110°C, and preferably 90°C to 110°C. When the melting point of the wax is 80°C or higher, the ink has excellent jetting properties. When the melting point of the wax is 110°C or lower, the ink has excellent abrasion resistance. In the present disclosure, the melting point refers to the temperature at the top of the endothermic peak in measurement using a differential scanning calorimeter (DSC), for example, a differential scanning calorimeter (product name "EXSTAR6220" manufactured by Hitachi High-Tech Science Corporation).

[0026] Waxes include natural waxes and synthetic waxes.

[0027] Examples of natural waxes include petroleum wax, vegetable wax, and animal and vegetable wax. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum. Examples of vegetable waxes include carnauba wax, candelilla wax, rice wax, and Japan wax. Examples of animal and vegetable waxes include lanolin and beeswax.

[0028] Examples of synthetic waxes include hydrocarbon waxes, modified waxes, and resin waxes. Examples of hydrocarbon waxes include polyolefin waxes (e.g., polyethylene (PE) wax, polypropylene (PP) wax), Fischer-Tropsch wax, and the like. Examples of modified waxes include paraffin wax derivatives, montan wax derivatives, microcrystalline wax derivatives, and fatty acid amide wax derivatives. Examples of resin waxes include acrylic wax, urethane wax, and the like.

[0029] Among these, from the viewpoint of improving blocking resistance in a high-humidity environment, the wax is preferably at least one selected from the group consisting of paraffin wax and hydrocarbon wax, more preferably hydrocarbon wax, and even more preferably polyolefin wax.

[0030] The wax preferably has an anionic group, which makes the wax self-dispersible in water and improves the storage stability and jetting properties of the ink.

[0031] Examples of the anionic group include a carboxy group, a sulfo group, a phosphate group, and a phosphonate group. Among these, from the viewpoint of dispersion stability, the anionic group is preferably a carboxy group or a sulfo group.

[0032] The wax is preferably in the form of particles having an average particle size of 200 nm or less. When the average particle size of the wax is 200 nm or less, the storage stability and ejection properties of the ink are improved. From the above viewpoints, the average particle size of the wax is more preferably 200 nm or less, and even more preferably 180 nm or less. The lower limit of the average particle size of the wax is, for example, 50 nm.

[0033] The average particle size of the wax is measured using a particle size distribution measuring device (for example, Microtrac UPA (registered trademark) EX150 manufactured by Nikkiso Co., Ltd.).

[0034] The wax content is preferably 1% by mass to 4% by mass, and more preferably 1.5% by mass to 2.5% by mass, based on the total amount of ink. When the wax content is 1% by mass or more, blocking resistance and abrasion resistance in high-humidity environments are improved. When the wax content is 4% by mass or less, image quality is improved.

[0035] (Polyoxyalkylene alkyl ether with an HLB value of 10 to 20) The ink of the present disclosure contains at least one polyoxyalkylene alkyl ether with an HLB value of 10 to 20. The polyoxyalkylene alkyl ether with an HLB value of 10 to 20 functions as a surfactant in the ink. Hereinafter, the polyoxyalkylene alkyl ether with an HLB value of 10 to 20 is also referred to as a "specific surfactant."

[0036] The ink of the present disclosure has excellent drying properties due to a low content of a high-boiling point solvent, which will be described later. Generally, as drying properties increase, the ink tends to have poor wetting and spreading properties and poor jetting properties. In contrast, the ink of the present disclosure contains a specific surfactant, which maintains drying properties and improves image quality through the ink's wetting and spreading properties, and further improves jetting properties.

[0037] The polyoxyalkylene alkyl ether is preferably a compound represented by the following formula (1): １ O-[(EO) ｍ / (PO) ｎ ]-H... Formula (1)

[0038] In formula (1), R １ represents a hydrocarbon group having 6 to 30 carbon atoms, EO represents an ethyleneoxy group, and PO represents a propyleneoxy group. In formula (1), m and n represent the average number of moles added, m is 2 to 100, n is 0 to 50, and the sum of m and n is 2 to 120.

[0039] In formula (1), “(EO) ｍ / (PO) ｎ " indicates that the arrangement of EO and PO may be that of a random copolymer or that of a block copolymer. ｍ / (PO)ｎ In the portion indicated as "," the order of addition of EO and PO does not matter.

[0040] In formula (1), when n is 2 or more, the compound represented by formula (1) may be a block copolymer or a random copolymer. When the compound represented by formula (1) is a block copolymer, it is a compound in which an oxyethylene group is located on the hydroxy group side, that is, R １ Preferably, the compound represented by formula (1) is O—(PO)(EO)—H. When the compound represented by formula (1) is a block copolymer, R １ It may also be a triblock copolymer of O-(EO)(PO)(EO)-H.

[0041] Commercially available specific surfactants include ethylene oxide adducts of lauryl alcohol, such as Emulgen 106 (HLB value: 10.5, average number of moles of EO added: 5), Emulgen 108 (HLB value: 12.1, average number of moles of EO added: 6), Emulgen 109P (HLB value: 13.6, average number of moles of EO added: 8), Emulgen 120 (HLB value: 15.3, average number of moles of EO added: 13), Emulgen 147 (HLB value: 16.3, average number of moles of EO added: 17), and Emulgen 150 (HLB value: 18.4, average number of moles of EO added: 47). Examples of ethylene oxide adducts of secondary alcohols having 12 carbon atoms include Triton (registered trademark) HW-1000 (HLB value: 10, average number of moles of EO added: 6), Tergitol TMN-6 (HLB value: 13.1, average number of moles of EO added: 8), Tergitol TMN-100X (HLB value: 14.0, average number of moles of EO added: 9), and Tergitol TMN-10 (HLB value: 14.4, average number of moles of EO added: 10). Other commercially available specific surfactants include Emulgen 707 (ethylene oxide adduct of secondary alcohol having 11 to 15 carbon atoms, HLB value: 12.1, average number of moles of EO added: 6) and Emulgen 220 (ethylene oxide adduct of linear primary alcohol having 16 to 18 carbon atoms, HLB value: 14.2, average number of moles of EO added: 13), manufactured by Kao Corporation.

[0042] From the viewpoint of further improving the ejection properties of the ink, the HLB value of the specific surfactant is preferably 12 to 20, and more preferably 15 to 20.

[0043] The HLB value of a particular surfactant is calculated using the Griffin method.

[0044] The ink may contain other surfactants in addition to the specific surfactant. Examples of other surfactants include acetylene compounds and silicone compounds. The acetylene compound has the effect of reducing dynamic surface tension and improving the wetting and spreading of the ink. The silicone compound has the effect of controlling static surface tension and suppressing bleeding between colors. From the above viewpoints, it is preferable that the ink contains the specific surfactant, the acetylene compound, and the silicone compound.

[0045] The content of the specific surfactant is preferably 0.5% by mass to 2% by mass, and more preferably 1% by mass to 1.5% by mass, relative to the total amount of ink. When the content of the specific surfactant is 0.5% by mass or more, the ink is easily wetted and spreads, improving image quality. When the content of the specific surfactant is 2% by mass or less, drying properties can be maintained.

[0046] (Water) The ink of the present disclosure contains water. The water content is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, relative to the total amount of the ink. The upper limit of the water content depends on the amounts of other components. The upper limit of the water content relative to the total amount of the ink is, for example, 90% by mass or 80% by mass.

[0047] (Organic Solvent) The ink of the present disclosure does not contain an organic solvent with a boiling point of 250° C. or higher, or the content of organic solvents with a boiling point of 250° C. or higher is 5 mass % or less relative to the total amount of the ink. Hereinafter, organic solvents with a boiling point of 250° C. or higher are also referred to as "high boiling point solvents."

[0048] If the ink does not contain a high-boiling point solvent, or if the content of the high-boiling point solvent is 5% by mass or less, the drying properties are improved.

[0049] In this disclosure, boiling point means the boiling point at 1 atmosphere (101,325 Pa).

[0050] Examples of high-boiling point solvents include glycerin (boiling point 290°C), triethylene glycol (boiling point 285°C), tripropylene glycol (boiling point 267°C), trimethylolpropane (boiling point 295°C), and triethylene glycol monobutyl ether (boiling point 276°C).

[0051] From the viewpoint of further improving drying properties, it is preferable that the ink does not contain a high-boiling point solvent. Furthermore, if the ink contains a high-boiling point solvent, the content of the high-boiling point solvent is preferably 2% by mass or less, and more preferably 1% by mass or less, of the total amount of the ink.

[0052] Furthermore, the ink of the present disclosure preferably does not contain any organic solvents having a boiling point of 150° C. or higher and lower than 250° C., or the content of organic solvents having a boiling point of 150° C. or higher and lower than 250° C. is preferably 21 mass % or less of the total amount of the ink. Hereinafter, organic solvents having a boiling point of 150° C. or higher and lower than 250° C. are also referred to as "medium-boiling point solvents."

[0053] If the ink does not contain a medium-boiling point solvent, or if the content of the medium-boiling point solvent is 21% by mass or less, the drying properties are further improved.

[0054] From the viewpoint of achieving both good wetting and spreading properties of the ink and good drying properties, the ink preferably contains a medium-boiling solvent, and the content of the medium-boiling solvent is preferably 5% to 21% by mass, and more preferably 8% to 18% by mass, of the total amount of the ink.

[0055] Examples of medium-boiling point solvents include propylene glycol (boiling point 188°C), 1,3-propanediol (boiling point 213°C), propylene glycol monomethyl ether (boiling point 121°C), ethylene glycol (boiling point 197°C), ethylene glycol monopropyl ether (boiling point 151°C), propylene glycol monobutyl ether (boiling point 170°C), ethylene glycol monobutyl ether (boiling point 171°C), 2-ethyl-1-hexanol (boiling point 187°C), dipropylene glycol monomethyl ether (boiling point 188°C), diethylene glycol monoethyl ether (boiling point 1 93°C), diethylene glycol dimethyl ether (boiling point 162°C), diethylene glycol diethyl ether (boiling point 188°C), dipropylene glycol dimethyl ether (boiling point 175°C), 1,2-hexanediol (boiling point 223°C), diethylene glycol (boiling point 245°C), diethylene glycol monobutyl ether (boiling point 230°C), dipropylene glycol (boiling point 232°C), 2-pyrrolidone (boiling point 245°C), tripropylene glycol monomethyl ether (boiling point 243°C), and triethylene glycol monomethyl ether (boiling point 248°C).

[0056] The ink of the present disclosure may also contain an organic solvent having a boiling point of less than 150° C. From the viewpoint of achieving both good wetting and spreading properties of the ink and good drying properties, it is preferable that the ink does not contain an organic solvent having a boiling point of less than 150° C., or that the content of organic solvents having a boiling point of less than 150° C. is 6% by mass or less of the total amount of the ink.

[0057] Examples of solvents with a boiling point of less than 150°C include propylene glycol monomethyl ether (boiling point 121°C), ethylene glycol monomethyl ether (boiling point 124°C), propylene glycol monoethyl ether (boiling point 133°C), ethylene glycol monoethyl ether (boiling point 135°C), and propylene glycol monopropyl ether (boiling point 149°C).

[0058] (Resin) Examples of the resin include pigment dispersion resin, resin particles, and water-soluble resin.

[0059] Pigment Dispersion Resin The resin may contain at least one pigment dispersing resin. In the present disclosure, a pigment dispersing resin is a resin that has the function of dispersing a pigment.

[0060] The form of the pigment dispersing resin is not particularly limited, and may be any of a random resin, a block resin, and a graft resin. The pigment dispersing resin is preferably a resin having a crosslinked structure.

[0061] The pigment contained in the ink is preferably at least partially coated with a resin having a crosslinked structure. When the pigment dispersing resin is a resin having a crosslinked structure and at least a portion of the pigment is coated with the pigment dispersing resin, it is thought that the pigment dispersing resin is less likely to detach from the surface of the pigment, and the dispersion stability of the pigment is high.

[0062] For example, the pigment can be mixed with an uncrosslinked resin and then crosslinked with a crosslinking agent, thereby coating at least a portion of the pigment with a resin having a crosslinked structure.

[0063] In this disclosure, a resin refers to a compound having a weight average molecular weight (Mw) of 1,000 or more.

[0064] In this disclosure, the weight average molecular weight (Mw) refers to a value measured by gel permeation chromatography (GPC). Measurements by gel permeation chromatography (GPC) are performed using an HLC (registered trademark)-8020GPC (manufactured by Tosoh Corporation) as a measuring device, three TSKgel (registered trademark) Super Multipore HZ-H columns (4.6 mm ID x 15 cm, manufactured by Tosoh Corporation), and THF (tetrahydrofuran) as an eluent. Measurements are performed using an RI detector at a sample concentration of 0.45% by mass, a flow rate of 0.35 mL / min, a sample injection volume of 10 μL, and a measurement temperature of 40°C. The calibration curve is prepared from eight samples of "Standard Sample TSK Standard, Polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0065] The resin having a crosslinked structure is not particularly limited as long as it has at least one crosslinked structure in the molecule.

[0066] Whether or not the resin contained in the ink has a crosslinked structure can be determined, for example, by the following method: First, the resin is separated from the ink using a separation method such as solvent extraction. The separated resin is analyzed using various analytical methods such as nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and thermal analysis, allowing a comprehensive determination of whether or not the resin has a crosslinked structure.

[0067] When preparing the ink of the present disclosure, a pigment dispersion in which a pigment is dispersed in a resin having a crosslinked structure may be used. The pigment dispersion may be a commercially available product. Examples of commercially available products include Projet Yellow APD1000, Projet Magenta APD1000, Projet Cyan APD1000, and Projet Black APD1000 (manufactured by FUJIFIL M Imaging Colorants).

[0068] Resin Particles: From the viewpoint of improving abrasion resistance, the resin preferably contains at least one type of resin particle. The resin particles contain a resin and may also contain a core material other than the resin, but are preferably resin particles consisting only of a resin.

[0069] The type of resin constituting the resin particles is not particularly limited, and examples of the resin particles include particles made of acrylic resin, particles made of polyester resin, particles made of polyurethane resin, and particles made of polyolefin resin.

[0070] In the present disclosure, an acrylic resin refers to a resin containing at least one of a structural unit derived from (meth)acrylic acid and a structural unit derived from a (meth)acrylic acid ester.

[0071] For the resin particles, reference may be made to, for example, paragraphs 0038 to 0114 of International Publication No. 2021 / 192720 and paragraphs 0109 to 0120 of JP-A-2015-25076.

[0072] From the viewpoint of abrasion resistance, the glass transition temperature of the resin particles is preferably 30°C to 100°C, more preferably 35°C to 80°C. Here, the glass transition temperature of the resin particles is a measured Tg obtained by actual measurement. For the measurement method of the measured Tg, see paragraph 0111 of JP 2015-25076 A.

[0073] When the ink contains resin particles, the content of the resin particles is preferably 0.5% to 7% by mass, and more preferably 1% to 6% by mass, relative to the total amount of the ink.

[0074] In the ink of the present disclosure, when the glass transition temperature of the resin particles is T1° C. and the melting point of the wax is T2° C., it is preferable that T1 and T2 satisfy the following formula (A): −30≦T2−T1≦50 (A).

[0075] When "T2-T1" is -30 to 50, the resin particles are likely to form a film and the wax is likely to become liquid, thereby improving the blocking resistance and abrasion resistance in a high-humidity environment. From the above viewpoints, "T2-T1" is more preferably 0 to 50, and even more preferably 10 to 40.

[0076] In the ink of the present disclosure, when the content of wax relative to the total amount of ink is W mass % and the content of resin particles relative to the total amount of ink is R mass %, it is preferable that W and R satisfy the following formula (B): 0≦R−W≦4 (B)

[0077] When "R-W" is 0 or more, the abrasion resistance is improved. When "R-W" is 4 or less, the image quality and ink ejection properties are improved. From the above viewpoints, "R-W" is more preferably 0 to 3, and even more preferably 0 to 2.5.

[0078] -Water-soluble resin- The resin may contain at least one water-soluble resin. In the present disclosure, "water-soluble" in "water-soluble resin" means that 1 g or more of the resin dissolves in 100 g of water at 25°C. Examples of water-soluble resins include polyalkylene glycols, vinyl resins, acrylic resins, urethane resins, and polyester resins.

[0079] When the ink contains a water-soluble resin, the content of the water-soluble resin is preferably 0.5% by mass to 5% by mass, and more preferably 1% by mass to 4% by mass, relative to the total amount of the ink.

[0080] (Other Components) The ink according to the present disclosure may contain other components in addition to the components described above, as necessary. Examples of other components include colloidal silica, inorganic salts, solid wetting agents (such as urea), anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, anti-fungal agents, pH adjusters, antifoaming agents, viscosity adjusters, dispersion stabilizers, anti-rust agents, chelating agents, and water-soluble polymer compounds.

[0081] (Physical Properties of Ink) - Viscosity - The viscosity of the ink is preferably 1.2 mPa·s to 15.0 mPa·s, more preferably 2.0 mPa·s to 13.0 mPa·s, and even more preferably 2.5 mPa·s to 10.0 mPa·s. The viscosity of the ink is measured at a temperature of 30°C using a rotational viscometer, for example, a product name "VISCOMETER TV-22" manufactured by Toki Sangyo Co., Ltd.

[0082] If the viscosity is 1.2 mPa·s or more, bleeding is suppressed, whereas if the viscosity is 15.0 mPa·s or less, excellent ejection properties are achieved.

[0083] - pH - From the viewpoint of storage stability of the ink, the pH of the ink is preferably 6.0 to 11.0, more preferably 7.0 to 10.0, and even more preferably 7.0 to 9.5. The pH of the ink is measured at 25°C using a pH meter, for example, a product name "WM-50EG" manufactured by Toa DKK Corporation.

[0084] [Image Recording Method] The image recording method of the present disclosure includes a step of applying the inkjet ink onto a recording medium by an inkjet recording method to record an image.

[0085] The recording medium is not particularly limited as long as it can record an image, and examples thereof include paper, cloth, wood, metal plate, and resin film. The recording medium may be surface-treated in advance. Among them, it is preferable to use a low-absorbency substrate (coated paper, cast-coated paper) for commercial printing.

[0086] Examples of surface treatments include corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, and light irradiation treatment.

[0087] Examples of paper include pure white roll paper, kraft paper, paperboard, fine paper, OCR paper, art paper, coated paper, cast coated paper, condenser paper, and wax paper.

[0088] Examples of resin films include polyester film, polypropylene (PP) film, cellophane, acetate film, polycarbonate (PC) film, acrylic resin film, polyethylene terephthalate (PET) film, biaxially oriented polystyrene (OPS) film, biaxially oriented polypropylene (OPP) film, biaxially oriented nylon (ONy) film, polyvinyl chloride (PVC) film, polyethylene (PE) film, and triacetate (TAC) film.

[0089] The inkjet recording method is not particularly limited as long as it is a method capable of recording an image, and may be any of known methods, such as a charge control method that uses electrostatic attraction to eject ink, a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink with it, thereby ejecting the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and uses the resulting pressure.

[0090] As an ink jet recording method, in particular, the method described in JP-A-54-59936 can be effectively used, in which ink subjected to the action of thermal energy undergoes a sudden change in volume, and the ink is ejected from a nozzle by the force resulting from this state change.

[0091] For the ink jet recording method, the method described in paragraphs 0093 to 0105 of JP-A No. 2003-306623 can also be referred to.

[0092] Inkjet heads used in inkjet recording methods include a shuttle method in which a short serial head is used and recording is performed while the head is scanned in the width direction of the substrate, and a line method in which a line head is used in which recording elements are arranged corresponding to the entire area of ​​one side of the substrate.

[0093] In the line method, a pattern can be formed over the entire surface of a substrate by scanning the substrate in a direction intersecting the arrangement direction of the recording elements, and a transport system such as a carriage for scanning a short head is not required.

[0094] Furthermore, since complicated scanning control of the carriage movement and the substrate is no longer necessary and only the substrate moves, a higher printing speed can be achieved compared to the shuttle method.

[0095] The amount of ink droplets ejected from the inkjet head is preferably 1 pL (picoliter) to 20 pL, and more preferably 1.5 pL to 10 pL, from the viewpoint of obtaining a high-definition image.

[0096] The image recording method of the present disclosure may include other steps in addition to the step of recording an image on a recording medium by inkjet recording, such as a step of drying the image after recording.

[0097] Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples as long as it does not depart from the gist of the disclosure.

[0098] [Ink Preparation] Cyan inks C1 to C29, C51 to C56, magenta ink M1, yellow ink Y1, and black ink K1 were prepared by mixing the components shown in Tables 1 to 4 to the amounts (% by mass) shown in Tables 1 to 4. The water content is the remaining amount when the total ink amount is taken as 100% by mass. Details of each component are as follows:

[0099] (Pigment dispersions) Black pigment dispersion: Product name "Pro-jet Black APD1000", manufactured by FUJIFILM Imaging Colorants, pigment concentration 14.0% by mass Cyan pigment dispersion: Product name "Pro-jet Cyan APD1000", manufactured by FUJIFILM Imaging Colorants, pigment concentration 14.0% by mass Magenta pigment dispersion: Product name "Pro-jet Magenta APD4000", manufactured by FUJIFILM Imaging Colorants, pigment concentration 20.0% by mass Yellow pigment dispersion: Product name "Pro-jet Yellow APD1000", manufactured by FUJIFILM Imaging Manufactured by Colorants, pigment concentration 15.4% by mass Each of the pigment dispersions contains a pigment, a dispersant, and water, and the pigment is dispersed in the water by the dispersant.

[0100] (Solvents) - Medium boiling point solvents - PG: Propylene glycol (boiling point 188°C), manufactured by ADEKA Corporation; 1,2-HD: 1,2-hexanediol (boiling point 223°C), manufactured by Toyo Gosei Co., Ltd.; DEGmEE: Diethylene glycol monoethyl ether (boiling point 193°C), manufactured by Daicel Corporation. - High boiling point solvents - Glycerin (boiling point 290°C), manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; TEG (triethylene glycol, boiling point 285°C), manufactured by Tokyo Chemical Industry Co., Ltd.

[0101] (Specific surfactants) E106: Product name "Emulgen 106", an ethylene oxide adduct of lauryl alcohol, average number of moles of EO added: 5, HLB value: 10.5, manufactured by Kao Corporation E108: Product name "Emulgen 108", an ethylene oxide adduct of lauryl alcohol, average number of moles of EO added: 6, HLB value: 12.1, manufactured by Kao Corporation E150: Product name "Emulgen 150", an ethylene oxide adduct of lauryl alcohol, average number of moles of EO added: 47, HLB value: 18.4, manufactured by Kao Corporation

[0102] (Other surfactants) E103: Product name "Emulgen 103", ethylene oxide adduct of lauryl alcohol, average number of EO moles added: 3, HLB value: 8.1, manufactured by Kao Corporation D604: Product name "Dynol 604", acetylene glycol surfactant, manufactured by Evonik Industries BYK-345: polyether-modified silicone surfactant (manufactured by BYK)

[0103] (Resin particles) - Aqueous dispersion of resin particles A: Polyester emulsion (product name "Vylonal MD-2000", manufactured by Toyobo MC Co., Ltd., Tg 67°C, particle size 150 nm) - Aqueous dispersion of resin particles B: Polyester emulsion (product name "Pesresin A-647GEX", manufactured by Takamatsu Oil & Fat Co., Ltd., Tg 60°C, particle size 102 nm) - Aqueous dispersion of resin particles C: Polyurethane emulsion (product name "Superflex 150", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Tg 40°C, particle size 30 nm) - Aqueous dispersion of resin particles D: Acrylic emulsion manufactured by the following manufacturing method, Tg 150°C, particle size 10 nm - Aqueous dispersion of resin particles E: Acrylic emulsion manufactured by the following manufacturing method, Tg 97°C, particle size 47 nm The numbers in the "Resin particles" column in Tables 1 to 4 mean the content as resin particles.

[0104] -Method for producing an aqueous dispersion of resin particles D- 360.0 g of methyl ethyl ketone was charged into a 2-liter three-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, and the temperature was raised to 75 ° C. Thereafter, while maintaining the temperature inside the flask at 75 ° C, a mixed solution consisting of 151.2 g of isobornyl methacrylate, 172.8 g of methyl methacrylate, 36.0 g of methacrylic acid, 72 g of methyl ethyl ketone, and 1.44 g of "V-601" (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise at a constant rate so that the dropwise addition was completed within 2 hours. After completion of the dropwise addition, a solution consisting of 0.72 g of "V-601" and 36.0 g of methyl ethyl ketone was added thereto, and the mixture was stirred at 75 ° C. for 2 hours. After that, a solution consisting of 0.72 g of "V-601" and 36.0 g of isopropanol was added thereto, and the mixture was stirred at 75 ° C. for 2 hours. Then, the temperature was raised to 85 ° C., and stirring was continued for another 2 hours to obtain a solution of isobornyl methacrylate / methyl methacrylate / methacrylic acid (= 42 / 48 / 10 [mass ratio]) copolymer. Next, 668.3 g of the obtained polymer solution was weighed, and 388.3 g of isopropanol and 145.7 mL of a 1 mol / L NaOH aqueous solution were added thereto, and the temperature in the reaction vessel was raised to 80 ° C. Next, 720.1 g of distilled water was added dropwise at a rate of 20 mL / min, and the mixture was dispersed in water. The reaction vessel temperature was then maintained at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure. Then, the pressure in the reaction vessel was reduced, and a total of 913.7 g of isopropanol, methyl ethyl ketone, and distilled water was distilled off to obtain an aqueous dispersion of resin particles D having a solids concentration (polymer particle concentration) of 28.0% by mass.

[0105] -Method for producing aqueous dispersion of resin particles E- A three-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with water (250 g), 12-methacrylamidodecanoic acid (6.7 g), potassium hydrogen carbonate (2.46 g), and isopropanol (20 g), and the temperature was raised to 85°C under a nitrogen stream. To this was added a mixed solution consisting of 4,4-azobis-4-cyanovaleric acid (radical polymerization initiator, product name "V-501", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (0.11 g), potassium hydrogen carbonate (0.08 g), and water (9 g), and the mixture was stirred for 10 minutes. Next, a monomer solution consisting of styrene (14 g), benzyl methacrylate (14 g), methyl methacrylate (48 g), butyl methacrylate (3.3 g), and hydroxylethyl methacrylate (14 g) was added dropwise to the three-neck flask at a constant rate so that the addition was completed within 3 hours. Furthermore, a mixed solution consisting of V-501 (0.06 g), potassium bicarbonate (0.04 g), and water (6 g) was added in two portions: immediately after the start of the addition of the monomer solution and 1.5 hours after the start of the addition of the monomer solution. After the addition of the monomer solution was completed, the mixture was stirred for 1 hour. Subsequently, a mixed solution consisting of V-501 (0.06 g), potassium bicarbonate (0.04 g), and water (6 g) was added to the resulting reaction mixture, and the mixture was stirred for an additional 3 hours. The resulting reaction mixture was filtered through a 50-m mesh to obtain an aqueous dispersion of resin particles E with a solids concentration (polymer particle concentration) of 24.8% by mass.

[0106] (Waxes) Polyethylene wax A: Product name "CA-383" aqueous dispersion of polyethylene wax, melting point 81°C, particle size 160 nm, manufactured by Chukyo Yushi Co., Ltd. Polyethylene wax B: Product name "CA-384" aqueous dispersion of polyethylene wax, melting point 100°C, particle size 180 nm, manufactured by Chukyo Yushi Co., Ltd. Polyethylene wax C: aqueous dispersion of polyethylene wax, melting point 104°C, particle size 213 nm Polyethylene wax D: aqueous dispersion of polyethylene wax, melting point 82°C, particle size 210 nm Paraffin wax A: product name "AQUACER 539", aqueous dispersion of paraffin wax, melting point 90°C, particle size 75 nm, manufactured by BYK. Paraffin wax B: product name "AQUACER 497", aqueous dispersion of paraffin wax, melting point 60°C, particle size 182 nm, manufactured by BYK. Carnauba wax: product name "Cellosol 524D", aqueous dispersion of carnauba wax, melting point 83°C, particle size 84 nm. Polyethylene wax E: product name "Hitec E-6314", aqueous dispersion of polyethylene wax (aqueous dispersion with a solids concentration of 35%, manufactured by Toho Chemical Industry Co., Ltd.), melting point 137°C, particle size 92 nm. Polyethylene waxes A to D have anionic groups. The numerical values ​​in the "wax" column in Tables 1 to 4 indicate the content as wax.

[0107] (Other ingredients) PEG6000: Product name "Polyethylene Glycol 6000", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Urea: Manufactured by Nissan Chemical Industries, Ltd.

[0108]

[0109]

[0110]

[0111]

[0112] Examples 1 to 29, Comparative Examples 1 to 6 Images were recorded using the prepared inks, and the following evaluations were carried out. The evaluation results are shown in Tables 5 and 6. Cyan inks C1 to C29 were designated Examples 1 to 29. Cyan inks C51 to C56 were designated Comparative Examples 1 to 6.

[0113] (Drying property) An inkjet head (product name "GELJET GX5000 Printer Head", manufactured by Ricoh Co., Ltd.) was used to record an image on a recording medium (product name "Mirror Coat Gold", manufactured by Oji Paper Co., Ltd.). The first to fourth inkjet heads were all arranged so that the nozzle arrangement direction was inclined at 75.7° with respect to the direction perpendicular to the conveyance direction of the recording medium. The droplet ejection interval was set to 240 milliseconds. Before image recording, the recording medium was subjected to corona treatment using a corona treatment device (product name "TEC-4XA", manufactured by Kasuga Electric Co., Ltd., set output 100 W, 0.5 reciprocation).

[0114] A corona-treated recording medium was fixed on a stage under an environment of 23±1°C temperature and 50±5% relative humidity, and each ink was loaded into the first inkjet head and the second inkjet head. The recording medium conveyance speed was set to 30.5 m / min. The ejection volume was 3.0 pL. The resolution was 1200 dpi (dots per inch) x 1200 dpi. The ink was ejected from each inkjet head to record a solid image (200% duty), resulting in a recorded image. After recording the solid image, the recording medium was placed on a hot plate at 70°C and dried for 6 seconds using a hair dryer. A roller wrapped around plain paper was rolled over the image-recorded surface, and the degree of ink transfer to the plain paper was visually confirmed. Drying was evaluated based on the degree of transfer. The evaluation criteria are as follows: A and B indicate levels that are acceptable for practical use. A: No ink transfer; B: Slight ink transfer. C: Significant ink transfer occurred.

[0115] (Image Quality) An image was recorded in the same manner as in the image recording in the evaluation of drying property above, except for the following changes, to obtain an image recording. Each ink was filled only in the first inkjet head, and a solid image (100% duty) was recorded. The image recording surface of the obtained image recording was visually inspected for the presence or absence of streaks. The image quality was evaluated based on the number of streaks. The evaluation criteria are as follows: A and B are levels that are acceptable for practical use. A: Almost no streaks were observed. B: A few streaks were observed. C: Many streaks were observed.

[0116] (Ejection Properties) Images were recorded in the same manner as in the image recording for the evaluation of drying properties, except for the following changes, to obtain image records. Photo paper (product name "Gasai," manufactured by Fujifilm Corporation) was used as the recording medium, and the ejection volume was 2.4 pL. Each ink was filled only in the first inkjet head, and the resolution in the nozzle arrangement direction x transport direction was 75 dpi x 1,200 dpi. 100 ink droplets per nozzle were ejected in 96 lines parallel to the transport direction to obtain image record A. The inkjet head was then left in this state for 5 minutes in an environment with a temperature of 23±1°C and a relative humidity of 50±5%. After leaving the ink, a new recording medium was installed, and ink was ejected under the same conditions as before leaving the ink, to obtain image record B. The image-recorded surfaces of image records A and B were visually inspected for areas where ink had not been ejected (non-ejected areas). The ejection properties were evaluated based on the amount of non-ejected areas. The evaluation criteria are as follows: AA, A, and B are at levels that present no practical problems. AA: There were no non-ejection areas in either image recording A or image recording B. A: There were a few non-ejection areas in at least one of image recording A and image recording B. B: There were non-ejection areas in at least one of image recording A and image recording B. C: There were many non-ejection areas in at least one of image recording A and image recording B.

[0117] (Blocking Resistance) An image was recorded in the same manner as in the image recording for the drying property evaluation, except for the following changes, to obtain an image recording. Each ink was filled only in the first inkjet head, and a solid image (100% duty) was recorded. The obtained image recording was cut into a size of 2 cm x 2 cm, and the image-recorded surfaces were overlapped with each other and a load of 1 kg was applied. After 24 hours of storage at a temperature of 40°C and a relative humidity of 85%, the overlapped portions were peeled off. The condition of the overlapped surfaces was visually observed. Blocking resistance was evaluated based on the peeling operation and the condition of the overlapped surfaces. The evaluation criteria are as follows: A and B are levels that are acceptable for practical use. A: No noise was generated during the peeling operation, and the image was peeled off cleanly. B: No noise was generated during the peeling operation, or one image-recorded surface peeled off slightly and transferred to the other image-recorded surface. C: One image-recorded surface peeled off significantly and transferred to the other image-recorded surface.

[0118] (Abrasion Resistance) An image was recorded in the same manner as in the image recording for the evaluation of blocking resistance above, to obtain an image recording. The obtained image recording was left to stand for 30 minutes. Thereafter, the image recording surface of the image recording was rubbed back and forth 10 times with a paperweight wrapped in rubbing paper. OK Topcoat (manufactured by Oji Paper Co., Ltd.) was used as the rubbing paper. The rubbing operation was performed with a load of 4.0 N applied. The condition of the image recording surface after rubbing was observed visually. The abrasion resistance was evaluated based on the condition of the image recording surface after rubbing. The evaluation criteria are as follows: A and B are levels that are acceptable for practical use. A: Almost no rubbing was observed on the image recording surface. B: The image recording surface was partially rubbed, and the color of the image was faded. C: The image recording surface was rubbed significantly, and the recording medium was visible.

[0119]

[0120]

[0082] As shown in Tables 5 and 6, Examples 1 to 29 contain a pigment, a wax, a polyoxyalkylene alkyl ether having an HLB value of 10 to 20, and water, and the wax has a melting point of 80°C to 110°C and does not contain an organic solvent having a boiling point of 250°C or higher, or the content of the organic solvent having a boiling point of 250°C or higher is 5% by mass or less relative to the total amount of the inkjet ink, and the content of the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 is 0.1% by mass to 2% by mass relative to the total amount of the inkjet ink. Therefore, it was found that it is possible to record images that are excellent in drying properties, abrasion resistance, and image quality while ensuring ejection properties.

[0121] On the other hand, in Comparative Example 1, the content of organic solvents with a boiling point of 250°C or higher exceeded 5% by mass, and it was found that the ink had poor drying properties. In Comparative Example 2, the HLB value of the polyoxyalkylene alkyl ether was less than 10, and it was found that the ink had poor jetting properties. In Comparative Example 3, the melting point of the wax was less than 80°C, and it was found that the ink had poor jetting properties. In Comparative Example 4, the melting point of the wax was greater than 110°C, and it was found that the ink had poor abrasion resistance. In Comparative Example 5, the wax content was less than 0.1% by mass, and it was found that the image quality was poor. In Comparative Example 6, the wax content was greater than 2% by mass, and it was found that the ink had poor drying properties.

[0122] In Example 11, the HLB value of the polyoxyalkylene alkyl ether was 12 to 20, and it was found that the image quality and discharge performance were superior compared to Example 12.

[0123] In Example 18, the content of polyoxyalkylene alkyl ether having an HLB value of 10 to 20 was 0.5% by mass to 2% by mass, and it was found that the image quality was superior to that of Example 19.

[0124] In Example 1, "T2-T1" was -30 to 50, and it was found that, compared with Examples 22 and 23, blocking resistance and abrasion resistance were excellent.

[0125] In Example 26, "R-W" was 0 or more, and it was found that the abrasion resistance was superior compared to Example 27. In Example 24, "R-W" was 4 or less, and it was found that the image quality and discharge performance were superior compared to Example 25.

[0126] In Example 1, the wax was at least one selected from the group consisting of paraffin wax and hydrocarbon wax, and it was found that, compared to Example 29, it had excellent discharge properties and blocking resistance.

[0127] In Example 1, the wax had an anionic group, and it was found that the ejection properties were superior to those of Example 5.

[0128] In Example 1, the wax was in the form of particles having an average particle size of 200 nm or less, and it was found that the ejection properties were superior compared to Examples 3 and 4.

[0129] In Example 14, the wax content was 1% by mass or more, and it was found that the blocking resistance and abrasion resistance were superior to those of Example 15. In Example 16, the wax content was 4% by mass or less, and it was found that the image quality and ejection performance were superior to those of Example 17.

[0130] In Example 9, the content of organic solvents having a boiling point of 150° C. or more and less than 250° C. was 21 mass % or less, and it was found that Example 9 had superior drying properties compared to Example 10.

[0131] Next, for the magenta ink M1, the yellow ink Y1, and the black ink K1, images were recorded and the above evaluations were carried out in the same manner as in Example 1. The evaluation results were all A, as in Example 1.

[0132] In addition, the inkjet head used in Example 1 was changed to the following inkjet head, and image recording was performed in the same manner as in Example 1, and the above evaluations were carried out. As in Example 1, the evaluation results were AA for ejection performance and A for all other items. Product name "KJ4B-1200", manufactured by Kyocera Corporation Product name "Samba G3L", manufactured by FUJIFILM Dimatix

[0133] Furthermore, image recording was performed using four inks: cyan ink C1, magenta ink M1, yellow ink Y1, and black ink K1. Specifically, the first inkjet head was filled with black ink K1, the second inkjet head with cyan ink C1, the third inkjet head with magenta ink, and the fourth inkjet head with yellow ink, and the inks were ejected from each inkjet head. Image recording was performed in the same manner as in Example 1, and the above evaluations were performed. As in Example 1, the ejection performance was AA, and all other performances were A.

[0134] The disclosure of Japanese Patent Application No. 2024-147960, filed on August 29, 2024, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. An inkjet ink comprising a pigment, a wax, a polyoxyalkylene alkyl ether having an HLB value of 10 to 20, and water, wherein the wax has a melting point of 80°C to 110°C, wherein the inkjet ink does not contain an organic solvent having a boiling point of 250°C or higher, or the content of the organic solvent having a boiling point of 250°C or higher is 5% by mass or less relative to the total amount of the inkjet ink, and wherein the content of the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 is 0.1% by mass to 2% by mass relative to the total amount of the inkjet ink.

2. The ink-jet ink according to claim 1, wherein the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 has an HLB value of 12 to 20.

3. The ink-jet ink according to claim 1, wherein the content of the polyoxyalkylene alkyl ether having an HLB value of 10 to 20 is 0.5% by mass to 2% by mass based on the total amount of the ink-jet ink.

4. The ink-jet ink according to claim 1, further comprising resin particles, wherein, when the glass transition temperature of the resin particles is T1°C and the melting point of the wax is T2°C, T1 and T2 satisfy the following formula (A): -30≦T2−T1≦50 (A).

5. The ink-jet ink according to claim 1, wherein W and R satisfy the following formula (B): 0≦R−W≦4 (B), where W is the content of the wax relative to the total amount of the ink-jet ink and R is the content of the resin particles relative to the total amount of the ink-jet ink.

6. The ink-jet ink according to claim 1, wherein the wax is at least one selected from the group consisting of paraffin wax and hydrocarbon wax.

7. The ink-jet ink of claim 1, wherein the wax has anionic groups.

8. The ink-jet ink according to claim 1, wherein the wax is in the form of particles having an average particle size of 200 nm or less.

9. The ink-jet ink according to claim 1, wherein the content of the wax is 1% by mass to 4% by mass relative to the total amount of the ink-jet ink.

10. The inkjet ink according to claim 1, which does not contain any organic solvent having a boiling point of 150°C or more but less than 250°C, or the content of organic solvents having a boiling point of 150°C or more but less than 250°C is 21% by mass or less of the total amount of the inkjet ink.

11. An image recording method comprising the step of applying the ink-jet ink according to any one of claims 1 to 10 onto a recording medium by an ink-jet recording method to record an image.

Images