Ink, inkjet printing method, and recording media

Abstract

Providing inks with excellent redispersibility. [Solution] An ink containing a water-insoluble colorant, an alkanolamine with a boiling point between 150°C and 350°C, and a compound represented by the following formula (1). [Formula 1] TIFF2026066969000005.tif28170[In formula (1), R 1 represents a linear or branched C1-C30 alkyl group. EO represents an ethylene oxy group, and PO represents a propylene oxy group. m and n each independently represent an integer from 1 to 6. The order in which EO and PO are bonded is arbitrary.

Description

Technical Field

[0001] The present invention relates to ink, an inkjet printing method, and a recording medium.

Background Art

[0002] Among various color printing methods, the printing method using an inkjet printer, which is one of the representative methods, generates small droplets of ink and attaches them to a printing medium such as paper to perform printing. In recent years, the demand for industrial applications has increased, and there is a need for ink that can print on various printing media.

[0003] Many printing media include ink-non-absorbent media such as resin films and ink-poorly absorbent media such as coated papers. As ink used for printing such recording media, non-aqueous solvent inks, curable inks, and the like are known. However, from the viewpoint of safety for, for example, the natural environment and living organisms, there is a strong demand for aqueous ink as an alternative to these inks. Such aqueous ink contains a water-insoluble colorant and a dispersant, and generally also contains a polymer, wax, or the like for the purpose of improving abrasion resistance, solvent resistance, and the like. Therefore, such aqueous ink has a high solid content and is extremely easy to dry. Drying of the ink causes the formation of solids in the nozzle portion of the inkjet head and in the ink flow path during long-term storage, storage in a high-temperature and low-humidity environment, etc., and clogging is likely to occur. When clogging occurs in the inkjet head in this way, the ink cannot be stably ejected. If the ink cannot be stably ejected, problems such as deterioration of the printed image quality and decrease in image density occur. Therefore, there is a need for ink that can be stably ejected and continuously ejected, that is, ink having excellent redispersibility such that even if solids of the ink are formed, the solids can be redispersed by the ink itself.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] This invention has been made in view of the above circumstances, and aims to provide an ink with excellent redispersibility. [Means for solving the problem]

[0006] The inventors of the present invention conducted extensive research to solve the above-mentioned problems and, as a result, discovered that an ink containing a water-insoluble colorant, an alkanolamine with a boiling point of 150°C to 350°C, and a compound represented by the following formula (1) can solve the above-mentioned problems, thus completing the present invention.

[0007] In other words, the present invention relates to the following 1) to 5). 1) An ink containing a water-insoluble colorant, an alkanolamine with a boiling point between 150°C and 350°C, and a compound represented by the following formula (1).

[0008] [ka]

[0009] In formula (1), R 1 represents a linear or branched C1-C30 alkyl group. EO represents an ethylene oxy group, and PO represents a propylene oxy group. m and n each independently represent an integer from 1 to 6. The order in which EO and PO are bonded is arbitrary. 2) Furthermore, the ink described in 1) contains an organic solvent. 3) Furthermore, the ink described in 1) or 2), which includes a binder resin. 4) An inkjet printing method that prints by ejecting droplets of ink described in any one of items 1) to 3) from an inkjet printer and adhering them to a printing medium. 5) Printed media to which ink described in any one of items 1) to 3) has been applied. [Effects of the Invention]

[0010] This invention provides an ink with excellent redispersibility. [Modes for carrying out the invention]

[0011] In this specification, unless otherwise specified, "parts" and "%" in the examples and other descriptions shall all be expressed on a mass basis.

[0012] The ink of the present invention comprises a water-insoluble colorant, an alkanolamine with a boiling point of 150°C or higher and 350°C or lower, and a compound represented by the above formula (1).

[0013] [Water-insoluble coloring agent] The water-insoluble colorants described above are not particularly limited as long as they are water-insoluble colorants. For example, known pigments, disperse dyes, solvent dyes, and water-insoluble resins colored with colorants such as dyes and pigments can be used. In this specification, a water-insoluble colorant means a colorant whose solubility in 1 liter of water at 25°C is usually 5 g or less, preferably 3 g or less, more preferably 1 g or less, and even more preferably 0.5 g or less. The lower limit of solubility includes 0 g. Unless otherwise specified, "water-insoluble colorant" may be abbreviated as "colorant" below. Among the above colorants, pigments are preferred. Examples of pigments include inorganic pigments, organic pigments, and extender pigments.

[0014] Examples of inorganic pigments include carbon black, titanium dioxide, metal oxides, hydroxides, sulfides, ferrocyanides, and metal chlorides.

[0015] As the colorant contained in the black ink, carbon blacks such as thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black are preferable. Specific examples of carbon black include, for example, the Raven series manufactured by Columbian Carbon; the Monarch series, Regal series, and Mogul series manufactured by Cabot Corporation; the ColorBlack series, Printex series, SpecialBlack series, and Nerox series manufactured by Orion Engineered Carbons; the MA series, MCF series, No. 25, No. 33, No. 40, No. 47, No. 52, No. 900, and No. 2300 manufactured by Mitsubishi Chemical Corporation, and the like.

[0016] Examples of organic pigments include various pigments such as azo, diazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perinone, thioindigo, anthraquinone, and quinophthalone.

[0017] Specific examples of organic pigments include, for example, yellows such as C.I.PigmentYellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 128, 129, 138, 139, 150, 151, 154, 155, 180, 185, 193, 199, 202, 213, etc.; reds such as C.I.PigmentRed 5, 7, 12, 48, 48:1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 168, 177, 178, 179, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 272, etc.; blues such as C.I.PigmentBlue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, 80, etc.; violets such as C.I.PigmentViolet 19, 23, 29, 37, 38, 50, etc.; oranges such as C.I.PigmentOrange 13, 16, 43, 68, 69, 71, 73, etc.; greens such as C.I.PigmentGreen 7, 36, 54, etc.; blacks such as C.I.PigmentBlack 1, 7, etc.

[0018] Examples of extender pigments include, for example, silica, calcium carbonate, talc, clay, barium sulfate, and white carbon, etc. Extender pigments are often used in combination with other colorants.

[0019] Examples of disperse dyes include well-known disperse dyes. Among these, dyes selected from CIDispers are preferred. Specific examples include, for instance, CIDispers Yellow 9, 23, 33, 42, 49, 54, 58, 60, 64, 66, 71, 76, 79, 83, 86, 90, 93, 99, 114, 116, 119, 122, 126, 149, 160, 163, 165, 180, 183, 186, 198, 200, 211, 224, 226, 227, 231, 237, etc.; CIDispers Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, 283, etc.; CIDispers Orange Disperse dyes in various colors are listed, including orange (9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, 97, etc.); violet (CIDispers Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, 79:1, etc.); and blue (CIDispers Blue 27, 56, 60, 79:1, 87, 143, 165, 165:1, 165:2, 181, 185, 197, 202, 225, 257, 266, 267, 281, 341, 353, 354, 358, 364, 365, 368, etc.).

[0020] The content of the colorant relative to the total mass of the above ink is typically 1 to 30%, preferably 1 to 10%, and more preferably 2 to 8%. The average particle size of the colorant is typically 50 to 350 nm, preferably 60 to 300 nm. In this specification, the average particle size refers to the average particle size measured using the laser light scattering method.

[0021] [Alkanolamines with a boiling point between 150°C and 350°C] The alkanolamines with a boiling point between 150°C and 350°C (hereinafter sometimes abbreviated as alkanolamines) are not particularly limited as long as they have a boiling point between 150°C and 350°C. Examples of the above alkanolamines include diethanolamine, triethanolamine, 2-amino-2-methyl-1-propanol, 2-(2-aminoethoxy)-ethanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(propylamino)ethanol, 2-(isopropylamino)ethanol, 2-(butylamino)ethanol, 2-(isobutylamino)ethanol, 2-(dimethylamino)-2-methyl-1-propanol, 2-(dibutylamino)ethanol, etc. Diethanolamine, triethanolamine, 2-amino-2-methyl-1-propanol, 2-(ethylamino)ethanol, and 2-(propylamino)ethanol are preferred, diethanolamine, triethanolamine, and 2-amino-2-methyl-1-propanol are more preferred, and 2-amino-2-methyl-1-propanol is even more preferred.

[0022] The boiling point of the above alkanolamine is preferably 150°C or higher and less than 340°C, more preferably 150°C or higher and less than 300°C, even more preferably 155°C or higher and less than 200°C, particularly preferably 160°C or higher and 180°C or lower, and extremely preferably 160°C or higher and 170°C or lower.

[0023] The alkanolamine contained in the above ink may be used alone or in combination of two or more types. The total content of the alkanolamine relative to the total mass of the ink is preferably 0.1% to 5% by mass, more preferably 0.1% to 3% by mass, even more preferably 0.2% to 2% by mass, particularly preferably 0.25% to 1.5% by mass, and especially preferably 0.25% to 1.2% by mass.

[0024] [Compound represented by formula (1)] In the above equation (1), R 1 represents a linear or branched C1-C30 alkyl group. EO represents an ethyleneoxy group, and PO represents a propyleneoxy group. m and n are integers from 1 to 6. The order in which EO and PO are bonded is arbitrary.

[0025] The above R 1 It is preferably a linear or branched C10-C18 alkyl group, more preferably a linear or branched C12-C15 alkyl group, and even more preferably a linear C12-C15 alkyl group.

[0026] The above m represents an integer from 1 to 6, preferably from 2 to 6.

[0027] The above n represents an integer from 1 to 6, and is preferably from 1 to 4.

[0028] The ratio of m to n is preferably in the range of 1 / 5 to 5 / 1, more preferably in the range of 1 / 4 to 4 / 1, even more preferably in the range of 1 / 3 to 3 / 1, and particularly preferably in the range of 1 / 2 to 3 / 2.

[0029] The above values ​​of m and n are both average values. Therefore, in this specification, if m and n have decimal values, the values ​​of m and n shall be obtained by rounding to the first decimal place and making them integers.

[0030] The content of the compound represented by formula (1) in the total mass of the above ink is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, even more preferably 0.2% by mass or more and 2% by mass or less, particularly preferably 0.25% by mass or more and 1.2% by mass or more, and especially preferably 0.3% by mass or more and 1.0% by mass or less.

[0031] The compound represented by formula (1) above can be synthesized by known methods. It is also available commercially. Specific examples of commercially available products include GENAPOL EP2424, EP2544, and EP2564 manufactured by Clariant.

[0032] In the above ink, if the total mass of the above alkanolamine is a and the total mass of the compound represented by formula (1) is b, the value obtained by a / b is preferably 0.1 to 10, more preferably 0.1 to 5, even more preferably 0.2 to 4, particularly preferably 0.25 to 3.5, especially preferably 0.25 to 1.5, and extremely preferably 0.5 to 1.25.

[0033] [Organic solvents] The above ink may also contain an organic solvent. Examples of organic solvents include C1-C6 alkanols having one hydroxyl group, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tertiary butanol, 3-methoxy-3-methyl-1-butanol, and 3-methoxy-1-butanol; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-methylpyrrolidine-2-one; cyclic ureas such as 1,3-dimethylimidazolidine-2-one and 1,3-dimethylhexahydropyrimido-2-one; ketones or keto alcohols such as acetone, 2-methyl-2-hydroxypentan-4-one, and ethylene carbonate; and tetrahydro Examples include cyclic ethers such as furan and dioxane; 1,2-(C2-C3) alkanediols such as ethylene glycol, propylene glycol, and 1,3-propanediol; oligos or polyalkylene glycols or thioglycols having C2-C4 alkylene units, such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol or polypropylene glycol with a molecular weight of 400 or more, thiodiglycol or dithiodiglycol; polyols (triols) such as glycerin, diglycerin, hexane-1,2,6-triol, and trimethylolpropane; γ-butyrolactone, and dimethyl sulfoxide, glycol ethers, and C4-C12 alkanediols.

[0034] The above ink preferably contains a glycol ether and a C4-C12 alkanediol as organic solvents.

[0035] The glycol ether is not particularly limited, but alkyl ethers of di or tri C2-C6 alkylene glycols are preferred, and monoalkyl ethers of di or tri C2-C6 alkylene glycols are more preferred. Examples of the C2-C6 alkylene glycol portion include ethylene glycol, propylene glycol, and butylene glycol. Among these, ethylene glycol and propylene glycol are preferred, with propylene glycol being more preferred. The range of carbon atoms in the alkyl ether portion is usually C1-C8, preferably C1-C7, more preferably C2-C6, even more preferably C3-C6, and particularly preferably C4-C6. In addition, phenyl ethers of di or tri-C2-C6 alkylene glycols are also preferred as the glycol ether, and the examples and preferred examples of the C2-C6 alkylene glycol portion in this case may be the same as above. Specific examples include, for instance, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether (butyl diglycol), diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, and diethylene glycol monophenyl ether. Among these, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, and dipropylene glycol monobutyl ether are preferred, and propylene glycol monobutyl ether or dipropylene glycol monobutyl ether are more preferred.

[0036] The above C4-C12 alkanediol is not particularly limited, but 1,2-(C4-C12)alkanediol is preferred, and 1,2-(C6-C8)alkanediol is more preferred. Alkanediols with 7 or more C7 are generally considered to be poorly water-soluble. Specific examples include 1,2-heptanediol, 1,2-octanediol, 5-methyl-1,2-hexanediol, 4-methyl-1,2-hexanediol, and 4,4-dimethyl-1,2-pentanediol. Among these, 1,2-octanediol is preferred. Furthermore, alkanediols with 6 or fewer C6 are generally considered to be water-soluble. Specific examples include 1,2-hexanediol, 1,2-pentanediol, 1,2-butanediol, 4-methyl-1,2-pentanediol, and 3,3-dimethyl-1,2-butanediol.

[0037] The above organic solvent is preferably at least one selected from the group consisting of 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-butanol, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and propylene glycol monobutyl ether, and is a combination of 3-methoxy-3-methyl-1-butanol and dipropylene glycol monobutyl ether, a combination of 3-methoxy-3-methyl-1-butanol and propylene glycol monobutyl ether, a combination of diethylene glycol monobutyl ether and dipropylene glycol monobutyl ether, and 3-methoxy-1-butanol It is preferable that the combination is one of 3-methoxy-3-methyl-1-butanol and dipropylene glycol monobutyl ether, more preferably one of the combinations of 3-methoxy-3-methyl-1-butanol and dipropylene glycol monobutyl ether, 3-methoxy-3-methyl-1-butanol and propylene glycol monobutyl ether, and even more preferably one of the combinations of 3-methoxy-1-butanol and dipropylene glycol monobutyl ether, and 3-methoxy-1-butanol and propylene glycol monobutyl ether.

[0038] The organic solvent contained in the above ink may be used alone or in combination of two or more types. The total content of the organic solvent relative to the total mass of the ink is preferably 0.1% to 25% by mass, more preferably 0.5% to 15% by mass, even more preferably 1% to 12% by mass, and particularly preferably 3% to 10% by mass.

[0039] The above ink may also contain a binder resin. The above binder is not particularly limited, but examples include one or more selected from condensation polymers such as polyurethane and polyester; and vinyl polymers such as (meth)acrylic resins, styrene resins, acrylic-styrene resins, butadiene resins, styrene-butadiene resins, vinyl chloride resins, vinyl acetate resins, and acrylic silicone resins. A (meth)acrylic resin is preferred as the above binder. The above-mentioned (meth)acrylic resins include copolymers composed of constituent monomers such as methacrylic acid, C1-C4 alkyl methacrylate, C6-C10 alkyl acrylate, and C2-C4 unsaturated alkyl methacrylate, and a reactive emulsifier having a radically polymerizable double bond in its molecule. Examples of copolymer types include block copolymers, random copolymers, and graft copolymers, with random copolymers being preferred. The polymer resin may also be in the form of a salt. The polymer resin can be synthesized by known methods.

[0040] Examples of C1-C4 alkyl methacrylates include those with a linear alkyl portion, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and n-butyl methacrylate; those with a branched alkyl portion, such as isopropyl methacrylate, isobutyl methacrylate, and t-butyl methacrylate; and those with a cyclic alkyl portion, such as cyclopropyl methacrylate and cyclobutyl methacrylate. Among these, those with a linear alkyl portion are preferred, C1-C3 alkyl methacrylates with a linear alkyl portion are more preferred, and methyl methacrylate is even more preferred. Examples of C6-C10 alkyl acrylates include those with a linear alkyl portion, such as hexyl acrylate, heptyl acrylate, octyl acrylate, nonyl acrylate, and decyl acrylate; those with a branched alkyl portion, such as isohexyl acrylate, isoheptyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, and isodecyl acrylate; and those with a cyclic alkyl portion, such as cyclohexyl acrylate, 4-t-butylcyclohexyl acrylate, cycloheptyl acrylate, cyclooctyl acrylate, cyclononyl acrylate, and cyclodecyl acrylate. Among these, those with a branched alkyl portion are preferred, C8 alkyl acrylate with a branched alkyl portion is more preferred, and 2-ethylhexyl acrylate is even more preferred. Examples of C2-C4 unsaturated alkyl methacrylates include vinyl methacrylate, allyl methacrylate, 2-butene methacrylate, 3-methyl-2-butene methacrylate, and 3-butene methacrylate, which are C2-C4 alkenyl methacrylates. Among these, C2-C4 alkenyl methacrylates are preferred, C3 alkenyl methacrylates are more preferred, and allyl methacrylates are even more preferred.

[0041] Reactive emulsifiers are emulsifiers that have a radically polymerizable double bond in their molecule. The number of radically polymerizable double bonds is usually one.

[0042] As the reactive emulsifier, an anionic type reactive emulsifier having an anionic group in its molecule is preferred. Such anionic type reactive emulsifiers are sometimes referred to as "reactive anionic surfactants." Examples of anionic groups include sulfonic acid groups, sulfonate groups, sulfate ester groups, phosphate groups, phosphate ester groups, nitrate ester groups, carboxyl groups, and salts thereof. Among these, sulfonic acid groups, sulfonate groups, sulfate ester groups, and salts thereof are preferred, and salts of sulfate ester groups are more preferred. Examples of salts include ammonium salts and alkali metal salts (e.g., sodium salts, potassium salts, etc.). It can be done.

[0043] Among reactive emulsifiers, ethylenically unsaturated monomers having a group selected from sulfonic acid groups, sulfonate groups, sulfate ester groups, phosphate groups, phosphate ester groups, and salts thereof are preferred.

[0044] Specific examples of reactive emulsifiers include polyoxyalkylene alkenyl ether sulfate ammonium, ether sulfate type ammonium, phosphate esters, bis(polyoxyethylene polycyclic phenyl ether) methacrylate sulfate, 2-sodium sulfoethyl methacrylate, alkoxy polyethylene glycol maleate, and salts thereof. Specific examples of reactive emulsifiers include sodium alkylallyl sulfosuccinate (Sanyo Chemical Industries, Ltd., Eleminor JS-20), dipotassium alkenylsuccinate (Kao Corporation, Latemul ASK), polyoxyethylene alkylpropenylphenyl ether sulfate (Daiichi Kogyo Seiyaku Co., Ltd., Aqualon HS-10), α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate (ADEKA Corporation, Adekaria Soap SE series such as Adekaria Soap SE-10N), and polyoxyethylene-1-(allyloxymethyl)alkyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., Aqualon KH-1025, etc.). Examples include the KH series), styrene sulfonates (manufactured by Tosoh Finechem Co., Ltd., spinomer NaSS), α-[2-[(allyloxy)-1-(alkyloxymethyl)]ethyl]-ω-polyoxyethylene sulfate (manufactured by ADEKA Corporation, Adekaria Soap SR series such as Adekaria Soap SR-1025), sulfate salts of polyoxyethylene polyoxybutylene (3-methyl-3-butenyl) ether (manufactured by Kao Corporation, Latemul PD-104), and ammonium salts of sulfated products of oxirane polyadducts of {C10-C14 branched chain alkanol and 1-(allyloxy)-2,3-epoxypropane}, mainly composed of [({α-[2-(allyloxy)-1-({C10-C14 alkyloxy}methyl)ethyl]-ω-hydroxypoly(n=1~100)(oxyethylene)}].Among these, the ammonium salt of the sulfated product of the reaction product of {C10-C14 branched chain alkanol and 1-(allyloxy)-2,3-epoxypropane}, mainly composed of {α-[2-(allyloxy)-1-({C10-C14 alkyloxy}methyl)ethyl]-ω-hydroxypoly(n=1~100)(oxyethylene)} is preferred.

[0045] Reactive emulsifiers are used together with monomers when synthesizing polymer resins. This allows for the production of polymer resin emulsions. When preparing the ink according to this embodiment, it is preferable to use such polymer resin emulsions.

[0046] There are no particular restrictions on the amount of reactive emulsifier used when synthesizing polymer resins. As a guideline for the amount used, it is usually 0.1 to 10% by mass, preferably 0.3 to 5% by mass, more preferably 0.5 to 3% by mass, and even more preferably 1 to 3% by mass, relative to the total mass of the four types of monomers mentioned above. By using the reactive emulsifier within the above range, it is possible to stably synthesize polymer resins, control the average particle size of the polymer resins to a suitable range, and adjust the viscosity of the polymer resin emulsion to a suitable range.

[0047] The average particle size of the polymer resin is typically 10 to 500 nm, preferably 20 to 200 nm, and more preferably 40 to 120 nm. By setting the average particle size within this range, clogging of the inkjet head and re-aggregation of the polymer resin tend to be suppressed.

[0048] In this embodiment, the lower limit of the polymer resin content (in terms of solid content) in the total mass of the ink is typically 0.1% by mass, preferably 0.2% by mass, and more preferably 0.3% by mass, while the upper limit is typically 10% by mass, preferably 7% by mass, more preferably 6% by mass, and even more preferably 5% by mass.

[0049] The above ink may also contain water. The water mentioned above is preferably water with a low content of impurities such as metal ions, i.e., ion-exchanged water, distilled water, etc. Such water can be prepared by known methods. The water content in the ink is preferably 55% to 90% by mass, and more preferably 60% to 85% by mass.

[0050] The above ink may also contain ink modifiers in addition to the above components. Examples of ink modifiers include polymer dispersants, waxes, viscosity modifiers, surfactants, preservatives, fungicides, pH adjusters, chelating agents, rust inhibitors, water-soluble UV absorbers, antioxidants, and defoamers.

[0051] The above-mentioned polymeric dispersant is not particularly limited as long as it is a polymer with a weight-average molecular weight of 2,500 or more that can disperse the above-mentioned water-insoluble colorant, and is other than the compound represented by formula (1) and the above-mentioned binder resin. In this specification, the above-mentioned polymeric dispersant may be abbreviated as dispersant. Known polymer dispersants can be used as the polymer dispersant. Examples of polymer dispersants include copolymers composed of at least two monomers selected from monomers such as styrene and its derivatives; vinylnaphthalene and its derivatives; aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids; (meth)acrylic acid and its derivatives; maleic acid and its derivatives; itaconic acid and its derivatives; fahric acid and its derivatives; vinyl acetate, vinyl alcohol, vinylpyrrolidone, acrylamide, and their derivatives (preferably at least one of which is a hydrophilic monomer). Examples of such copolymers include styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, (meth)acrylic acid ester-(meth)acrylic acid copolymer, polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymer, and styrene-maleic acid copolymer. Among these, styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, and (meth)acrylic acid ester-(meth)acrylic acid copolymers are preferred, (meth)acrylic acid ester-(meth)acrylic acid copolymers are more preferred, and methacrylic acid ester-methacrylic acid copolymers are even more preferred. Examples of copolymer types include block copolymers, random copolymers, and graft copolymers. These copolymers may also be in the form of salts.

[0052] Dispersants can be obtained commercially or synthesized.

[0053] Examples of commercially available dispersants include Joncyrl 62, 67, 68, 678, and 687 (styrene-acrylic copolymers manufactured by BASF); Movinyl S-100A (modified vinyl acetate copolymer manufactured by Japan Coating Resin Co., Ltd.); and Julimer AT-210 (polyacrylic acid ester copolymer manufactured by Toagosei Co., Ltd.).

[0054] Examples of dispersants obtained by synthesis include the AB block polymer disclosed in International Publication No. 2013 / 115071. The monomer constituting the A block of the AB block polymer disclosed in International Publication No. 2013 / 115071 is at least one monomer selected from (meth)acrylic acid and linear or branched C4 alkyl (meth)acrylate, with at least one monomer selected from methacrylic acid and n-butyl methacrylate being preferred, and more preferably a combination of these two monomers. The monomer constituting the B block of the AB block polymer disclosed in International Publication No. 2013 / 115071 is at least one monomer selected from benzyl methacrylate and benzyl acrylate, with benzyl methacrylate being preferred. Specific examples of AB block polymers include the block copolymers disclosed in Synthesis Examples 3 to 8 of International Publication No. 2013 / 115071.

[0055] The acid value of the dispersant is typically 90-200 mgKOH / g, preferably 100-150 mgKOH / g, and more preferably 100-120 mgKOH / g.

[0056] A neutralizing agent may be used to uniformly disperse the dispersant in water. Examples of neutralizing agents include ammonia, alkali metal hydroxides, alkaline earth metal hydroxides, aliphatic amine compounds, and alkanolamine compounds. Among these, ammonia and alkali metal hydroxides are preferred, with ammonia being more preferred. As a guideline for the amount of neutralizing agent to use, the degree of neutralization is usually 30-300%, preferably 50-200%, with 100% neutralization being defined as neutralization with a theoretical equivalent amount of the acid value of the dispersant.

[0057] The mass-average molecular weight of the dispersant is typically 10,000 to 60,000, preferably 10,000 to 40,000, more preferably 15,000 to 30,000, and even more preferably 20,000 to 25,000. The mass-average molecular weight of the dispersant can be measured by gel permuration chromatography (GPC). Specifically, the measurement can be performed using an HLC-8320GPC (manufactured by Tosoh Corporation) as the GPC instrument, two TSK gel Super Multipore HZ-H columns (manufactured by Tosoh Corporation, inner diameter 4.6 mm × 15 cm), tetrahydrofuran as the eluent, and TSK Standard (manufactured by Tosoh Corporation) as the standard sample.

[0058] The PDI (mass-average molecular weight / number-average molecular weight) of the dispersant is preferably around 1.29 to 1.49. Within this range, the dispersibility and storage stability of the ink tend to be good.

[0059] The dispersant can be used in a mixed state with the colorant. Alternatively, it can be used with part or all of the surface of the colorant coated with the dispersant. Or, both of these states may be used in combination.

[0060] As the above wax, a wax emulsion is preferred, and a water-based wax emulsion is more preferred. Natural waxes and synthetic waxes can be used as the wax. Examples of natural waxes include petroleum-based waxes such as paraffin wax and microcrystalline wax; lignite-based waxes such as montane wax; plant-based waxes such as candelilla wax; and emulsions in which waxes such as beeswax and lanolin, which are dispersed in an aqueous medium.

[0061] Examples of synthetic waxes include polyalkylene wax (preferably poly C2-C4 alkylene wax), oxidized polyalkylene wax (preferably oxidized poly C2-C4 alkylene wax), and paraffin wax. Of these, one or more waxes selected from polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, and paraffin wax are preferred, with oxidized polyethylene wax being more preferred. Furthermore, the average particle size of the wax is preferably 30 nm to 5 μm, and more preferably 50 nm to 1 μm, in order to prevent clogging of the inkjet head.

[0062] Examples of commercially available wax emulsions include AQUACER 515 and 1547 from BIC Chemie Japan, and the HYTEC E series from Toho Chemical Industry Co., Ltd., such as E-6500, E-9015, and E-6314.

[0063] The above ink may contain a viscosity modifier. In particular, industrial inkjet printers typically have a defined viscosity range for the ink that can be ejected, based on the specifications of the printer head (the head that ejects the ink). Therefore, a viscosity modifier can be added to the ink to adjust its viscosity to an appropriate range. The viscosity modifier is not particularly limited as long as it is a substance that can adjust the viscosity of the ink; known substances can be used. Specific examples include the polymer dispersants mentioned above.

[0064] The above ink may contain a surfactant. The surfactant is not particularly limited as long as it is not a compound represented by formula (1) above, but examples include anionic, cationic, nonionic, silicon-based, and fluorine-based surfactants.

[0065] Examples of anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acyl amino acids or their salts, N-acyl methyl taurates, alkyl sulfates, polyoxyalkyl ether sulfates, alkyl sulfates, polyoxyethylene alkyl ether phosphates, rosinic acid soaps, castor oil sulfates, lauryl alcohol sulfates, alkylphenol type phosphates, alkyl type phosphates, alkylaryl sulfonates, diethyl sulfosaturates, diethylhexyl sulfosaturates, and dioctyl sulfosaturates.

[0066] Examples of cationic surfactants include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.

[0067] Nonionic surfactants include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers with 4 to 18 carbon atoms (e.g., polyoxyethylene butyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene 2-ethylhexyl ether), and polyoxyethylene (di)styrene-modified phenyl ether (e.g., Emulgen manufactured by Kao Corporation). Ether-based compounds such as A-60, A-90, A-500, and DSP-9, DSP-12.5, TSP-7.5, KTSP-16, TSP-50 from Aoki Oil Co., Ltd.; ester-based compounds such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; acetylene glycol (or acetylene alcohol)-based compounds such as 2,4,7,9-tetramethyl-5-decine-4,7-diol, 3,6-dimethyl-4-octin-3,6-diol, and 3,5-dimethyl-1-hexyn-3-ol (for example, Surfinol 420, 440, 465, 485, and Orphine from Evonik Japan Co., Ltd.). Examples include STG, E1004, E1040, etc.; and polyglycol ether-based compounds.

[0068] Examples of silicone-based surfactants include polyether-modified siloxanes and polyether-modified polydimethylsiloxanes. Examples include Dynol 960 and 980 from Air Products Corporation; Silface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG009, and SAG010 from Nisshin Chemical Co., Ltd.; and BYK-345, 347, 348, 349, 3450, 3451, and 3455 from BYK Additives & Instruments; and TEGO Twin 4000, TEGO Wet KL 245, 250, 260, 265, 270, and 280 from Evonic Tego Chemie.

[0069] Examples of fluorinated surfactants include 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 their side chains. Specific examples of commercially available products include Capstone FS-30 and FS-31 (manufactured by Chemours).

[0070] Examples of the above-mentioned preservatives include compounds such as organosulfur, organonitrogen-sulfur, organohalogen, haloarylsulfone, iodopropagyl, haloalkylthio, nitrile, pyridine, 8-oxyquinoline, benzothiazole, isothiazolin, dithiol, pyridine oxide, nitropropane, organotin, phenol, quaternary ammonium salt, triazine, thiazine, anilide, adamantane, dithiocarbamate, brominated indanone, benzylbromacetate, and inorganic salts. Specific examples of commercially available preservatives include Proxel GXL(S) and XL-2(S) manufactured by Arch Chemical.

[0071] Examples of the above-mentioned antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethion-1-oxide, ethyl p-hydroxybenzoate, and 1,2-benzisothiazolin-3-one, as well as salts thereof.

[0072] Examples of the pH adjusting agents mentioned above include other alkanolamines other than those with a boiling point of 150°C to 350°C, such as diethanolamine, triethanolamine, and N-methyldiethanolamine; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide (ammonia water); or alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; and inorganic bases such as disodium phosphate.

[0073] The pH of the above ink is typically 5 to 11, preferably 7 to 10. The surface tension of the ink is typically 20 to 60 mN / m, preferably 25 to 50 mN / m. The viscosity of the ink is typically 2 to 30 mPa·s, preferably 3 to 15 mPa·s. The pH and surface tension of the ink can be adjusted by using pH adjusters, surfactants, and organic solvents.

[0074] Examples of the chelating agents mentioned above include disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uracil diacetate, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0075] Examples of the above-mentioned rust inhibitors include acidic sulfites, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitride, pentaerythritol tetranitrate, and dicyclohexylammonium nitride.

[0076] Examples of the above-mentioned water-soluble ultraviolet absorbers include, for example, sulfonated benzophenone compounds, benzotriazol compounds, salicylic acid compounds, cinnamic acid compounds, and triazine compounds.

[0077] Examples of the above antioxidants include, for example, various organic and metal complex-based colorfastness inhibitors. Examples of the above organic colorfastness inhibitors include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, ascorbic acid, isoascorbic acid, chlorogenic acid, sulfur dioxide, catechins, dibutylhydroxytoluene, tocopherol, and butylhydroxyanisole.

[0078] The above-mentioned defoaming agents include acetylene-based defoaming agents such as the Surfinol 104 series (104A, 104E, 104H, 104PA, 104PG-50), Surfinol DF110D, Surfinol AD01, Surfinol MD-20, Surfinol DF-58, BYK-017, BYK-018, BYK-019, BYK-021, BYK-022, BYK-023, BYK-024, BYK-025, BYK-028, BYK-044, BYK-092, BYK-1610, BYK-1611, BY Examples of defoaming agents include silicone-based defoamers such as K-1615, BYK-1617, BYK-1650, BYK1679, BYK-1719, BYK-1723, BYK-1724, BYK-1730, BYK-1770, BYK-1781, BYK-1786, and BYK-1789; mineral oil-based defoamers such as BYK-035, BYK-037, BYK-038, and BYK-1630; higher alcohol derivatives such as Bisform CS, Bisform ECC, and Bisform TDI-1; and fatty acid derivatives such as Bisform TS-10. The defoaming agent is preferably an acetylene-based or silicone-based defoamer.

[0079] The ink of the present invention has excellent redispersibility, ejection properties, fixation to printing media, and storage stability.

[0080] The above ink can be used in various printing applications. For example, it is suitable for writing instruments, various types of printing, information printing, textile printing, etc., and is particularly preferred for use in inkjet printing.

[0081] When preparing the above ink, known manufacturing methods can be used. For example, one method involves preparing an ink by adding the above alkanolamine, the compound represented by formula (1), water, and optionally an organic solvent, binder resin, and ink preparation agent to an aqueous dispersion prepared from the above water-insoluble colorant and polymer dispersant, and then mixing the mixture.

[0082] The above ink can be prepared using conventionally known equipment, such as a ball mill, sand mill, attritor, basket mill, or roll mill. During preparation, it is preferable to remove coarse particles using a membrane filter or mesh filter.

[0083] Furthermore, it is preferable to microfilter the ink. When microfiltration is performed, a membrane filter and / or glass filter paper can be used. The pore size of the filter used for microfiltration is usually 0.5 μm to 20 μm, preferably 0.5 μm to 10 μm.

[0084] An ink set containing at least the above-mentioned inks is also included in the present invention. Examples of the above-mentioned ink sets include an ink set containing two or more of the above-mentioned inks, an ink set containing one or more of the above-mentioned inks and one or more of other inks. The other inks other than the above-mentioned inks are not particularly limited as long as their composition is different from the above-mentioned inks, but it is preferable that they have a different hue from the above-mentioned inks.

[0085] The above ink and ink set are preferably used in inkjet printing.

[0086] <Inkjet Printing Method> The present invention also includes an inkjet printing method in which ink droplets are ejected from an inkjet printer and applied to a printing medium to perform printing.

[0087] Any known inkjet method can be used. Specific examples of inkjet methods include, for example, charge control methods, drop-on-demand (pressure pulse) methods, acoustic inkjet methods, and thermal inkjet methods, with the drop-on-demand method being preferred. In addition, inkjet methods also include methods that improve image quality by ejecting many small volumes of ink with a low pigment content, methods that improve image quality by using multiple inks with substantially the same hue but different pigment concentrations, and methods that improve pigment fixation by using colorless and transparent ink.

[0088] <Print media> Printing media to which the above-mentioned ink is attached are also included in the present invention. The printing media is not particularly limited as long as it is a material to which the above-mentioned ink can adhere, and examples include paper, film, cans, leather, cloth, and fibers. Printing media can be broadly classified into non-permeable printing media such as films and cans to which ink does not penetrate, and permeable printing media to which ink does penetrate.

[0089] Regarding all of the above, combinations of preferred elements are more preferable, and combinations of preferred elements are even more preferable. The same applies to combinations of preferred elements and preferred elements, and combinations of preferred elements and even more preferable elements. Furthermore, unless otherwise specified, all of the above-mentioned components can be used individually or in combination of two or more elements. [Examples]

[0090] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The "water" used in the examples is "ion-exchanged water".

[0091] [Preparation Example 1]: Preparation of a yellow pigment dispersion. 4.5 parts of BYKJET9151 (BYK Chemie Japan Co., Ltd.) were dissolved in 80.5 parts of deionized water and stirred for 1 hour. 15 parts of CIPigment Yellow 155 (Heubach GmbH, Inkjet Yellow H4G) were added to the resulting solution and dispersed in a sand grinder at 1500 rpm for 10 hours. 30 parts of deionized water were added dropwise to the resulting liquid, and the dispersion beads were removed by filtration to obtain yellow pigment dispersion 1 with a pigment solid content of 11.5%. [Preparation Examples 2-6] The pigment dispersions for Preparation Examples 2 to 6 were obtained in the same manner as in Preparation Example 1, except that the type of pigment added was as shown in Table 1 below.

[0092] [Table 1]

[0093] [Preparation Example 7]: Preparation of binder resin 1. A binder resin 1 with a solid content concentration of 40% was obtained by synthesizing a binder sample described in Synthesis Example 3 of Japanese Patent Publication No. 2024-146796.

[0094] [Example 1]: Preparation of Ink 1 The yellow pigment dispersion 1 obtained above was mixed with the components listed in Table 2 below, and then filtered through a 3 μm membrane filter to obtain ink 1 for evaluation testing. [Examples 2-19, Comparative Examples 1-3] Inks for Examples 2-19 and Comparative Examples 1-3 were obtained in the same manner as in Example 1.

[0095] The composition and redispersibility evaluation results of each prepared ink are shown in Table 2 below. In Table 2 below, the value "as100" indicates the set value by mass percentage of the solid content of the water-insoluble colorant contained in the ink when 100 parts of the ink are prepared, and it indicates that the amount of each dispersion is added to achieve this set value. The abbreviations in Table 2 below represent the following: PY155: Yellow pigment dispersion obtained in Preparation Example 1 PR122: Magenta pigment dispersion obtained in Preparation Example 2 PB15:4: Cyanide pigment dispersion obtained in Preparation Example 3 CB: Black pigment dispersion obtained in Preparation Example 4 PO43: Orange pigment dispersion obtained in Preparation Example 5 PG7: Green pigment dispersion obtained in Preparation Example 6 Surfinol 440: Surfinol 440 manufactured by Evonik GENAPOL EP2544: GENAPOL EP2544 manufactured by Clariant (in formula (1) above, R 1 (A compound in which C12-C15 alkyl groups, m is 2-4, n is 2-4, and m:n is in a 1:1 ratio) GENAPOL EP2424: GENAPOL EP2424 manufactured by Clariant (in formula (1) above, R 1 (A compound in which C12-C14 alkyl groups, m is 1-3, n is 2-5, and m:n is in a 1:2 ratio) GENAPOL EP2564: GENAPOL EP2564 manufactured by Clariant (in formula (1) above, R 1 (A compound in which C12-C15 alkyl groups, m is 6, n is 4, and m:n ratio is 3:2) Binder resin 1: Binder resin 1 of preparation example 7

[0096] [Table 2]

[0097] [Assessment of redistribution] Using a glass capillary with an inner diameter of 0.29 mm (AS ONE, EM Meister Ring Caps 5 μL, 1 / 5 division), the inks of Examples 1-19 and Comparative Examples 1-3 were drawn up to 30 mm (two divisions) from the bottom of the capillary by capillary action. The ink-filled capillaries were then fixed vertically and left to stand in a 40°C constant temperature and humidity chamber for 10 minutes. Afterward, the bottom of the capillary was immersed in a screw-cap vial containing 10 g of the same ink as the one drawn up. The time taken for the ink to be drawn up to 75 mm (five divisions) from the bottom of the capillary was measured and evaluated according to the following criteria. [Evaluation Criteria] A: Less than 2 minutes B: 2 minutes or more but less than 3 minutes C: 3 minutes or more but less than 5 minutes D: More than 5 minutes

[0098] As shown in the results in Table 2 above, the example inks exhibit excellent redispersibility. [Industrial applicability]

[0099] The ink of this invention exhibits excellent redispersibility.

Claims

1. An ink containing a water-insoluble colorant, an alkanolamine with a boiling point between 150°C and 350°C, and a compound represented by the following formula (1). 【Chemistry 1】 [In formula (1), R １ represents a linear or branched C1-C30 alkyl group. EO represents an ethyleneoxy group, and PO represents a propyleneoxy group. m and n each independently represent an integer from 1 to 6. The order in which EO and PO are bonded is arbitrary.

2. Furthermore, the ink according to claim 1, comprising an organic solvent.

3. Furthermore, the ink according to claim 1 or 2, further comprising a binder resin.

4. An inkjet printing method that involves ejecting ink droplets according to claim 1 or 2 from an inkjet printer and adhering them to a printing medium for printing.

5. A printing medium to which the ink described in claim 1 or 2 is attached.

Images