Aqueous ink and printed matter

Abstract

To provide an aqueous ink that employs biomass-derived material but enables recording of an image having alcohol resistance comparable to or exceeding that of an image recorded with a conventional ink prepared substantially without use of biomass-derived material, and a printed matter obtained using the aqueous ink.SOLUTION: An aqueous ink contains a colorant and a resin containing a unit derived from biomass-derived acrylonitrile, and a printed matter includes an image formed with the aqueous ink.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to water-based inks and printed matter. [Background technology]

[0002] In recent years, inkjet recording methods have been widely used when printing and producing indoor and outdoor exhibits such as posters. Indoor and outdoor exhibits are required to have properties that prevent defects such as image damage and peeling even when exposed to alcohol, and maintain image quality (hereinafter also referred to as "alcohol resistance"). To meet these requirements, inks containing resins as binders or inks containing pigment dispersions using alkali-soluble resins as dispersants are used.

[0003] Furthermore, in response to recent concerns about the depletion of fossil resources and efforts to prevent global warming, the use of renewable biomass-derived materials is being recommended, and inks with a high biomass content, which contain resins synthesized using biomass-derived materials, have been proposed (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-8569 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to provide an aqueous ink that uses a biomass-derived material but is capable of recording images that have alcohol resistance equal to or greater than that of images recorded with conventional inks prepared substantially without using biomass-derived materials. Another object of the present invention is to provide printed materials obtained using this aqueous ink. [Means for solving the problem]

[0006] That is, according to the present invention, there is provided a water-based ink comprising a colorant and a resin containing a unit derived from biomass-derived acrylonitrile. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an aqueous ink that uses a biomass-derived material but is capable of recording images that have alcohol resistance equal to or greater than that of images recorded with conventional ink prepared substantially without using a biomass-derived material. Furthermore, according to the present invention, it is possible to provide a printed material obtained using this aqueous ink. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in further detail below with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt is present in the ink as dissociated ions, but for convenience it will be expressed as "containing a salt." Inkjet ink may also be referred to simply as "ink." Physical property values ​​are values ​​at room temperature (25°C) unless otherwise specified. The terms "(meth)acrylic acid" and "(meth)acrylate" refer to "acrylic acid, methacrylic acid" and "acrylate, methacrylate," respectively.

[0009] The present inventors investigated the composition of an ink that uses biomass-derived materials but can print images with alcohol resistance equivalent to or greater than that of images printed with conventional inks prepared substantially without biomass-derived materials. Specifically, they compared the characteristics of images printed with an ink containing a resin containing units derived from biomass-derived acrylonitrile with those printed with an ink containing a resin containing units derived from petroleum-derived acrylonitrile. As a result, they found that there was no significant difference in the characteristics between the two, leading to the present invention. Therefore, the technology described herein can contribute to the realization of a sustainable society, such as a decarbonized / recycling-based society.

[0010] <Water-based ink> The ink of the present invention is a water-based ink suitable for inkjet printing, which contains a colorant and a resin containing a unit derived from biomass-derived acrylonitrile. The ink of the present invention will be described in detail below.

[0011] (resin) The ink contains a resin containing units derived from biomass-derived acrylonitrile. The content (mass %) of the resin in the ink is preferably 3.0% to 20.0% by mass, and more preferably 4.5% to 10.0% by mass, based on the total mass of the ink.

[0012] The higher the content of acrylonitrile-derived units in a resin, the lower the ink's recovery ability tends to be. Because acrylonitrile is a highly polar monomer, resins with a high content of acrylonitrile-derived units strongly interact with highly polar components such as water and water-soluble organic solvents in ink that has been concentrated by water evaporation. As a result, a gel-like substance that is difficult to remove even with recovery treatments is likely to form, which is thought to reduce the ink's recovery ability.

[0013] The content (% by mass) of units derived from biomass-derived acrylonitrile in the resin is preferably 10% by mass to 60% by mass, and more preferably 15% by mass to 50% by mass, based on the total mass of the resin. By using a resin with a content of units derived from biomass-derived acrylonitrile within the above range, the alcohol resistance of the image can be further improved and the ink adhesion recovery can be enhanced.

[0014] The inventors prepared an ink containing a resin with a content of units derived from biomass-derived acrylonitrile of 10% by mass or more and an ink containing a resin with a content of units derived from petroleum-derived acrylonitrile of 10% by mass or more. They then compared the alcohol resistance of images printed with these inks. As a result, it was found that the ink containing a resin with a content of units derived from biomass-derived acrylonitrile of 10% by mass or more can print images exhibiting equal to or better alcohol resistance, even if the content of the units is lower. The reason for this difference is not entirely clear, but it is presumed to be due to differences in the adsorption of colorants to the resin, such as impurities derived from biomass. Thus, it is expected that using a smaller amount of biomass-derived acrylonitrile than petroleum-derived acrylonitrile will enable printing of images exhibiting equal to or better alcohol resistance.

[0015] Biomass-derived acrylonitrile can be produced according to known methods using biomass as a raw material. For example, biomass-derived acrylonitrile can be obtained by reacting biomass-derived propylene with ammonia and oxygen in the presence of a catalyst. Biomass-derived propylene can also be produced by cracking bionaphtha obtained from vegetable waste oil or animal waste oil. Biomass-derived propylene can also be produced by using ethylene prepared from bioethanol. Furthermore, propylene may be produced by a mass balance approach, such as cracking a mixture of bionaphtha and petroleum-derived naphtha.

[0016] The resin preferably further contains other units in addition to the units derived from biomass-derived acrylonitrile. The other units are units formed by other monomers other than acrylonitrile. Examples of the other monomers include (meth)acrylic acid and (meth)acrylic acid esters. The resin preferably further contains a unit derived from acrylic acid or methacrylic acid. The resin preferably further contains a unit derived from a (meth)acrylic acid ester. The resin preferably further contains a unit derived from acrylic acid or methacrylic acid, and a unit derived from a (meth)acrylic acid ester. The resin preferably further contains a unit derived from acrylic acid or methacrylic acid and has carboxylic acid groups in its molecule, and at least a portion of the carboxylic acid groups are preferably neutralized with an alkali such as potassium hydroxide.

[0017] Examples of acrylic acid esters include ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 1-methylheptyl acrylate, n-heptyl acrylate, tetrahydrofurfuryl acrylate, lauryl acrylate, isobornyl acrylate, tridecyl acrylate, docosyl acrylate, stearyl acrylate, n-octyl acrylate, isoamyl acrylate, and 2-ethylhexyl acrylate.

[0018] Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 1-methylheptyl methacrylate, n-heptyl methacrylate, tetrahydrofurfuryl methacrylate, lauryl methacrylate, isobornyl methacrylate, tridecyl methacrylate, docosyl methacrylate, stearyl methacrylate, dodecyl methacrylate, ethylene glycol dimethacrylate, and cyclohexyl methacrylate.

[0019] The resin may be either a water-soluble resin or resin particles. In the present invention, "resin particles" refers to a resin that exists in a state in which it is not dissolved in the aqueous medium that constitutes the ink. More specifically, it refers to a resin that can exist in the aqueous medium in a state in which it has formed particles whose particle diameter can be measured by dynamic light scattering. On the other hand, "water-soluble resin" refers to a resin that exists in a state in which it has dissolved in the aqueous medium that constitutes the ink. More specifically, it refers to a resin that can exist in the aqueous medium in a state in which it has not formed particles whose particle diameter can be measured by dynamic light scattering. Resin particles, when expressed as the counterpart of "water-soluble resin", are called "water-dispersible resin (water-insoluble resin)".

[0020] Resin particles may be in the form of surfactant-emulsified or dispersed resin particles, self-dispersed resin particles, or core-shell resin particles. Whether a resin is a "resin particle" can be determined according to the following method. First, a liquid containing the resin to be determined is diluted with pure water to prepare a sample with a resin content of approximately 1.0%. Then, when the particle size of the resin in the sample is measured by dynamic light scattering, if particles having the particle size are measured, the resin is determined to be a "resin particle" (i.e., a "water-dispersible resin"). On the other hand, if particles having the particle size are not measured, the resin is determined not to be a "resin particle" (i.e., a "water-soluble resin"). The measurement conditions can be, for example, Set Zero: 30 seconds, number of measurements: 10, measurement time: 120 seconds, shape: spherical, refractive index: 1.5, and density: 1.0. As the particle size distribution measuring device, a particle size analyzer using dynamic light scattering (for example, the trade name "Nanotrac WAVEII-Q" manufactured by Microtrac Bell) can be used. Of course, the particle size distribution measuring device and measurement conditions to be used are not limited to those described above.

[0021] The acid value of the water-soluble resin is preferably 10 mgKOH / g or more and 200 mgKOH / g or less. If the acid value of the water-soluble resin is less than 10 mgKOH / g, the ink ejection stability may be slightly reduced. On the other hand, if the acid value of the water-soluble resin is more than 200 mgKOH / g, the amount of hydration increases, making it difficult to dry and slightly reducing film strength. As a result, the effect of improving the alcohol resistance of the image may be slightly reduced. The acid value of the water-soluble resin can be controlled by adjusting the ratio of carboxylic acid group-containing monomers used in synthesizing the resin.

[0022] The weight-average molecular weight of the water-soluble resin is preferably 5,000 or more and 20,000 or less. If the weight-average molecular weight of the water-soluble resin is less than 5,000, the resin molecules may not easily entangle with each other within the image. This may result in a slight lack of film strength and a reduced effect in improving alcohol resistance. On the other hand, if the weight-average molecular weight of the water-soluble resin is more than 20,000, the viscosity of the ink may increase excessively, and the ink ejection stability may be slightly reduced.

[0023] When the resin forms resin particles, the cumulative 50% particle diameter (D 50 ) (hereinafter also referred to as "average particle diameter") is preferably 50 nm or more and 250 nm or less. If the average particle diameter of the resin particles is less than 50 nm, the ejection stability of the ink may be slightly reduced. On the other hand, if the average particle diameter of the resin particles is more than 250 nm, irregularities caused by the resin particles may be easily formed on the image surface. Then, stress may be easily transmitted by being caught on the formed irregularities, and the effect of improving alcohol resistance may be reduced.

[0024] The weight-average molecular weight of the resin (water-insoluble resin) that forms the resin particles is preferably 1,000,000 or less. If the weight-average molecular weight of the water-insoluble resin exceeds 1,000,000, the resin particles tend to settle and coalesce in the ink, increasing their particle size, which may reduce the effect of improving the storage stability of the ink.

[0025] The preferred range of the weight average molecular weight is different between a resin containing a unit derived from biomass-derived acrylonitrile and a resin containing a unit derived from petroleum-derived acrylonitrile. The molecular chain of the resin containing a unit derived from biomass-derived acrylonitrile contains a carbon-14 ( 14 C). For this reason, it is thought that resin particles formed from a resin containing units derived from biomass-derived acrylonitrile have a higher specific gravity and are more likely to settle than resin particles formed from a resin containing units derived from petroleum-derived acrylonitrile. Therefore, from the perspective of further improving the storage stability of the ink, the preferred weight-average molecular weight of a resin containing units derived from biomass-derived acrylonitrile is smaller than the weight-average molecular weight of a resin containing units derived from petroleum-derived acrylonitrile.

[0026] Since the resin particles are used as a constituent of the ink, they are preferably dispersed in an aqueous medium in the form of a dispersion. The aqueous medium is primarily composed of water, such as deionized water, ion-exchanged water, or distilled water, and may further contain a water-soluble organic solvent as needed. The water content (mass %) in the aqueous medium is preferably 50 mass % or more based on the total mass of the aqueous medium, and it is also preferable to use a liquid medium (i.e., water) that does not substantially contain a water-soluble organic solvent.

[0027] Examples of methods for forming resin particles by granulating a resin include emulsion polymerization, mini-emulsion polymerization, seed polymerization, dispersion, and phase inversion (emulsion) methods. Dispersion methods include the following methods (1) and (2). (1) A method in which a resin is dissolved in an organic solvent and the resulting solution is added to an aqueous medium to disperse the resin. (2) A method in which a resin is added to an organic solvent, and then an aqueous medium is added and mixed to disperse the resin.

[0028] The phase inversion (emulsification) method includes a method in which an aqueous medium is added to a solution obtained by dissolving a resin in an organic solvent, and the resin is precipitated in the form of particles during the process of phase inversion from a solvent system to an aqueous system. In either method, it is preferable to use a known disperser to granulate the resin while applying an appropriate shear force, and adjust the particle size of the resulting resin particles. Since the particle size of the resulting resin particles can be adjusted with precision, it is preferable to produce resin particles by emulsion polymerization.

[0029] The resin particles may be dyed with a coloring material. Examples of methods for dyeing the resin particles include a method of forming resin particles by polymerizing a monomer mixture in which a dye is dissolved, and a method of adding a dye to resin particles and heating the particles. Among these, the method of adding a dye to resin particles and heating the particles is preferred because it can be used with a wider variety of dyes.

[0030] When the colorant is a pigment, a resin is preferably used as a dispersant for dispersing the pigment. The resin used as a dispersant is preferably a copolymer of biomass-derived acrylonitrile and acrylic acid or methacrylic acid. Furthermore, the resin used as a dispersant is more preferably a copolymer of biomass-derived acrylonitrile, a (meth)acrylic acid ester, and acrylic acid or methacrylic acid. It is preferable that at least a portion of the carboxylic acid groups in these copolymers are neutralized with an alkali. By using such a copolymer (resin) as a dispersant, it is possible to prepare an aqueous pigment dispersion or ink that is less susceptible to pigment aggregation and precipitation and has excellent dispersibility. The copolymer may be in the form of a random copolymer, a block copolymer, or a graft copolymer. Furthermore, when a resin is used as a dispersant, the amount of dispersant used is preferably 20 to 50 parts by mass per 100 parts by mass of the colorant (pigment).

[0031] The pigment dispersion can be prepared by a dispersion method using a dispersion device or a production method in which dispersion conditions such as dispersion time, peripheral speed, and, if necessary, the type and particle size of the media used are appropriately set. Examples of the dispersion device include a roll mill, a bead mill, a paint shaker, a sand mill, an agitator mill, a nanomizer, a homogenizer, a microfluidizer, an ultimizer, and an ultrasonic disperser.

[0032] (colorant) The ink contains a colorant. The content (mass %) of the colorant in the ink is preferably 0.05% by mass or more and 15.0% by mass or less, and more preferably 0.1% by mass or more and 10.0% by mass or less, based on the total mass of the ink.

[0033] Dyes and pigments can be used as colorants. Examples of dyes include direct dyes, acid dyes, basic dyes, disperse dyes, food dyes, and oil-based dyes. Among these, it is preferable to use a dye having an anionic group. Specific examples of dye skeletons include xanthene, azine, azole, thiazole, azo, diarylmethane, triarylmethane, acridine, coumarin, methine, triphenylmethane, phthalocyanine, azaphthalocyanine, and anthrapyridone. When using resin particles dyed with a dye (dyed resin particles), it is preferable to use a basic dye, and it is more preferable to use a dye having a xanthene skeleton. Among these, CI Basic Red 1 (1:1), CI Basic Violet 11 (11:1), CI Basic Yellow 40, and the like are preferred due to their excellent color development.

[0034] Examples of pigments include inorganic pigments such as carbon black and titanium oxide; and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, and dioxazine. Pigment dispersion methods include resin-dispersed pigments, which use a resin as a dispersant, and self-dispersed pigments, in which hydrophilic groups are bonded to the pigment particle surface. Resin-bonded pigments, in which organic groups containing a resin are chemically bonded to the pigment particle surface, and microencapsulated pigments, in which the pigment particle surface is coated with a resin, can also be used. Biomass-derived colorants are preferably used as colorants. However, conventional colorants derived from petroleum resources can also be used.

[0035] (aqueous medium) The ink is an aqueous ink containing at least water as the aqueous medium. The ink may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. Deionized water or ion-exchanged water is preferably used as the water. The water content (mass %) in the ink is preferably 50.0% to 95.0% by mass, based on the total mass of the ink. Furthermore, the water-soluble organic solvent content (mass %) in the ink is preferably 3.0% to 50.0% by mass, based on the total mass of the ink.

[0036] Examples of the water-soluble organic solvent include glycol ethers, alkanols having 1 to 4 carbon atoms, carboxylic acid amides, ketones or ketoalcohols, cyclic ethers, glycols, polyethylene glycols, acetylene glycol derivatives, polyhydric alcohols, heterocycles, and sulfur-containing compounds.

[0037] Examples of glycol ethers include diethylene glycol monomethyl (or ethyl) ether and triethylene glycol monoethyl (or butyl) ether. Examples of alkanols having 1 to 4 carbon atoms include methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, isobutanol, and t-butanol. Examples of carboxylic acid amides include N,N-dimethylformamide and N,N-dimethylacetamide. Examples of ketones or ketoalcohols include acetone, methyl ethyl ketone, and 2-methyl-2-hydroxypentan-4-one. Examples of cyclic ethers include tetrahydrofuran and dioxane.

[0038] Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, and butylene glycol. Examples of polyethylene glycols include those having a number-average molecular weight of 200 to 2,000, more specifically, those having number-average molecular weights of 200, 400, 600, 1,000, and 2,000. Examples of polyhydric alcohols include glycerin, 3-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,2,6-hexanetriol. Examples of heterocyclic rings include 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and N-methylmorpholine. Examples of sulfur-containing compounds include thiodiglycol and dimethyl sulfoxide.

[0039] (Other ingredients) In addition to the above components, the ink may contain, if necessary, organic compounds that are solid at room temperature, such as trimethylolethane and trimethylolpropane, and nitrogen-containing compounds, such as urea and ethyleneurea. In addition to the above components, the ink may further contain, if necessary, various additives, such as surfactants, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, reduction inhibitors, evaporation accelerators, and chelating agents.

[0040] <Printed material> The printed matter of the present invention includes a substrate and an image formed on the surface of the substrate. The image is formed using the aqueous ink described above. Because the printed matter of the present invention contains a biomass-derived material, it is an environmentally friendly printed matter from the viewpoint of carbon neutrality.

[0041] The substrate can be a recording medium used in a recording method such as an inkjet recording method. Any recording medium can be used and can be selected depending on the intended use of the recorded image. Examples of the recording medium include permeable paper, such as plain paper or a recording medium having a coating layer. For example, plain paper, which is suitable for obtaining images such as business documents, can be used. Furthermore, glossy paper, which is suitable for obtaining images with a glossy appearance similar to photographic quality, and art paper, which makes use of the texture of the substrate (such as matte, drawing paper, canvas, or Japanese paper), can be used to express paintings, photographs, and graphic images according to preference. In particular, it is preferable to use a recording medium such as plain paper without a coating layer or a recording medium such as coated paper with a coating layer.

[0042] In addition, plastic films (recording media in which a plastic film is adhered to the recording surface of a substrate, or recording media in which an organic resin coating layer is provided on the recording surface of a substrate containing cellulose pulp) can be used as low to non-absorbent recording media. [Example]

[0043] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as the gist of the invention is not exceeded. The terms "parts" and "%" used to describe the amounts of components are based on mass unless otherwise specified.

[0044] <Methods for measuring physical properties> (average particle size of resin particles) Using a dynamic light scattering particle size analyzer, the average particle size of the resin particles (particle size at 50% of the cumulative volumetric particle size distribution) was measured under the following conditions: Set Zero: 30 seconds, number of measurements: 3, measurement time: 180 seconds, shape: spherical, refractive index: 1.59. The particle size analyzer used was the "UPA-EX150" (manufactured by Nikkiso).

[0045] (resin acid value) The acid value of the resin was measured according to the following method in accordance with JIS K 0070. (1) Accurately weigh 0.5 to 2.0 g of sample. The mass of the accurately weighed sample is defined as M (g). (2) Place the sample in a 50 mL beaker and add 25 mL of a mixture of tetrahydrofuran / ethanol (mass ratio = 2 / 1) to dissolve the sample. (3) Using a potentiometric titration device, titration is performed with a 0.1 mol / L ethanol solution of potassium hydroxide (KOH solution). As the potentiometric titration device, for example, an automatic titration device manufactured by Hiranuma Sangyo Co., Ltd. (product name "COM-2500") can be used. (4) The amount of KOH solution used in the titration is S (mL). At the same time, measure a blank and let the amount of KOH solution used be B (mL). (5) The acid value of the resin is calculated using the following formula (1): In the formula (1), f represents the factor of the KOH solution. Acid value of resin (mgKOH / g) = (SB) × f × 5.61 / M (1)

[0046] (weight average molecular weight of resin) The weight average molecular weight of the resin was measured by gel permeation chromatography (GPC) under the following conditions: Apparatus: Alliance GPC 2695 (Waters) Column: Shodex KF-806M 4-column (Showa Denko) ·Mobile phase: THF (special grade) ·Flow rate: 1.0mL / min Oven temperature: 40.0℃ Sample solution injection volume: 0.1 mL Detector: RI (refractive index) Polystyrene standards: PS-1 and PS-2 (manufactured by Polymer Laboratories, molecular weights: 7,500,000, 2,560,000, 841,700, 377,400, 320,000, 210,500, 148,000, 96,000, 59,500, 50,400, 28,500, 20,650, 10,850, 5,460, 2,930, 1,300, 580, 17 types).

[0047] <Preparation of water-soluble resin> (Water-soluble resin 1~15) A flask equipped with a stirrer, nitrogen inlet tube, reflux condenser, and thermometer was charged with 200.0 parts of isopropanol, and the temperature was raised to 85°C under a nitrogen atmosphere while stirring. A mixture of monomers and a polymerization initiator, the types and amounts (units: parts) shown in Table 1, were added dropwise to the flask over 2 hours while maintaining the internal temperature at 80°C. The mixture was stirred at 80°C for 4 hours to form a resin. After adding 0.9 equivalents of potassium hydroxide relative to the acid value of the resin and an appropriate amount of ion-exchanged water, the isopropanol was removed under reduced pressure to obtain a liquid containing a water-soluble resin with a resin content of 20.0%. All resins were dissolved in the resulting liquid, and no resin particles were formed. The acid values ​​and weight-average molecular weights of water-soluble resins 1 to 15 are shown in Table 1. The abbreviations in Table 1 are defined below. St: Styrene AN: Acrylonitrile BMA: n-butyl methacrylate AA: Acrylic acid V-59: 2,2'-azobis(2-methylbutyronitrile) (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0048] The biomass-derived acrylonitrile used was obtained by subjecting biomass-derived propylene to an ammoxidation reaction in which ammonia and oxygen were reacted with the biomass-derived propylene in the presence of a metal oxide catalyst, followed by removal of impurities such as hydrocyanic acid.

[0049] TIFF2025185927000001.tif119170

[0050] <Preparation of resin particles> (Resin particles 1 to 16) A reaction vessel equipped with a stirrer was placed in a hot water bath. 1,178 parts of water was placed in the reaction vessel, and the internal temperature was maintained at 70°C. 466 parts of a monomer mixture was prepared by mixing the types and amounts (unit: %) of monomers shown in Table 2. An aqueous solution of a polymerization initiator was prepared by mixing 1.9 parts of potassium persulfate and 659 parts of water. For resin particles 15 and 16, the amounts of potassium persulfate were 0.6 and 0.5 parts, respectively. The monomer mixture and the aqueous solution of the polymerization initiator were added dropwise to the reaction vessel over one hour. After the addition, stirring was continued and the reaction was continued for another 30 minutes to form resin particles. An appropriate amount of an 8 mol / L aqueous potassium hydroxide solution was added to the reaction vessel to adjust the pH of the liquid to 8.5.

[0051] For resin particles 2, 80 parts of a monomer mixture for the shell portion were prepared by mixing monomers in a ratio of 37.0% styrene, 20.0% methacrylic acid, 40.0% ethylene glycol dimethacrylate, and 3.0% reactive surfactant. The reactive surfactant used was α-sulfo-ω-(1-alkoxymethyl-2-(2-propenyloxy)ethoxy)-poly(oxy-1,2-ethanediyl)ammonium salt (trade name "ADEKA REASOAP SR-10", manufactured by ADEKA). An aqueous solution of polymerization initiator was prepared by mixing 0.1 parts of potassium persulfate and 133 parts of water. The monomer mixture for the shell portion and the aqueous solution of polymerization initiator were added dropwise in parallel over 10 minutes to a reaction vessel containing particles that would become the core portion. After the addition was completed, the mixture was stirred at 80°C for 10 minutes to continue the reaction and form the shell portion. This resulted in the formation of resin particles with a core-shell structure, in which the particles that would become the core portion were coated with the resin that would become the shell portion. An appropriate amount of 8 mol / L potassium hydroxide aqueous solution was added to the reaction vessel to adjust the pH of the liquid to 8.5.

[0052] For resin particles 3, 29 parts of a powdered dye mixture was prepared by mixing 80.0% CI Basic Red 1 and 20.0% CI Basic Violet 11. The prepared dye mixture was added to a reaction vessel and heated to 80°C. The mixture was stirred for 2 hours to form dyed resin particles. An appropriate amount of 8 mol / L potassium hydroxide aqueous solution was added to the reaction vessel to adjust the pH of the liquid to 8.5.

[0053] An appropriate amount of water was further added to obtain aqueous dispersions of resin particles 1 to 16 with a resin particle content of 20.0%. The average particle size of the resin particles and the weight average molecular weight of the resin constituting the resin particles are shown in Table 2. The meanings of the abbreviations in Table 2 are as follows: St: Styrene AN: Acrylonitrile 2EHA: 2-ethylhexyl acrylate ·MAA: methacrylic acid SR-10: α-sulfo-ω-(1-alkoxymethyl-2-(2-propenyloxy)ethoxy)-poly(oxy-1,2-ethanediyl)ammonium salt (trade name "ADEKA REASOAP SR-10", manufactured by ADEKA)

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[0055] <Preparation of pigment dispersion> (Pigment dispersion 1-15) 22.5 parts of a liquid containing a water-soluble resin, 15.0 parts of a pigment (CI Pigment Blue 15:3), and 47.5 parts of ion-exchanged water were mixed. A batch-type vertical sand mill (manufactured by Imex) filled with 85 parts of 0.3 mm diameter zirconia beads was used to carry out a dispersion process for 3 hours with water cooling. The mixture was centrifuged to remove coarse particles, and then pressure-filtered through a 3.0 μm pore-size microfilter (manufactured by Fujifilm) to obtain pigment dispersions 1 to 15 shown in Table 3, each with a pigment content of 15.0% and a water-soluble resin content of 4.5%.

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[0057] <Ink Preparation> (Ink 1-48) The components shown below were mixed and thoroughly stirred, and then pressure filtered through a microfilter (manufactured by Fujifilm) with a pore size of 3.0 μm to prepare inks 1 to 48. Cabojet 250C: Amount (parts) shown in Tables 4-1 to 4-4 Pigment dispersion liquid of the type shown in Tables 4-1 to 4-4: 33.3 parts Liquids containing water-soluble resins of the types shown in Tables 4-1 to 4-4: Amounts (parts) shown in Tables 4-1 to 4-4 Aqueous dispersion of resin particles of the types shown in Tables 4-1 to 4-4: 22.5 parts Glycerin: 10.0 parts 1,2-Hexanediol: 5.0 parts Polyethylene glycol (number average molecular weight 1,000): 3.0 parts Acetylenol E100: 0.5 parts Proxel GXL(S): 0.2 parts Ion-exchanged water: The remaining amount (parts) that makes the total of all ingredients 100.0 parts

[0058] "Cabojet250C" is the trade name of a self-dispersing cyan pigment dispersion (manufactured by Cabot Japan, pigment concentration 10.0%). "Acetylenol E100" is the trade name of a nonionic acetylene glycol surfactant (manufactured by Kawaken Fine Chemicals). "Proxel GXL(S)" is the trade name of a preservative (manufactured by Arch Chemicals).

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[0060] TIFF2025185927000005.tif107170

[0061] TIFF2025185927000006.tif108170

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[0063] <Evaluation> The following items were evaluated, and the results are shown in Table 5.

[0064] (reducing environmental impact) The ink was evaluated for its reduction in environmental impact according to the following evaluation criteria. ○: Uses a resin containing units derived from biomass-derived monomers, contributing to the reduction of greenhouse gas emissions. ×: Resin containing no units derived from biomass-derived monomers is used, and does not contribute to reducing greenhouse gas emissions.

[0065] (alcohol resistant) Each ink was filled into an ink cartridge and inserted into an inkjet recording device (product name "PIXUS iP3100" manufactured by Canon) that ejects ink from a recording head using thermal energy. In this example, the recording duty of a solid image recorded under conditions of depositing one 5 pL ink droplet per droplet in a unit area of ​​1 / 1,200 inch x 1 / 1,200 inch was defined as 100%. Using the inkjet recording device, a 200 mm x 200 mm solid image (recording duty 100%) was recorded on a recording medium (product name "Aurora Coat" manufactured by Nippon Paper Industries Co., Ltd.). The recorded image was dried at 25°C for 24 hours and then heated at 100°C for 5 minutes in a heating oven. After the heated image was returned to 25°C, 0.1 g of 70% ethanol aqueous solution was applied. After 1 minute, it was wiped off with a cellulose nonwoven fabric. The alcohol resistance of the image was evaluated according to the following evaluation criteria. A: There were no traces of droplets on the image. B: The ratio of the area of ​​the exposed recording medium to the area of ​​the droplets was less than 5%. C: The ratio of the area of ​​the exposed recording medium to the area of ​​the droplets was 5% or more.

[0066] (Discharge stability) Using the inkjet recording device described above, images were recorded on an A4-sized recording medium (PPC paper, product name "GF-500," manufactured by Canon). Specifically, two 19 cm x 26 cm solid images with a recording duty of 100% were recorded, followed by a 30-minute pause, followed by another two similar solid images. This procedure constituted one cycle. The recording conditions were a temperature of 23°C and a relative humidity of 55%. The ejection volume per droplet was within 28 ng ± 10% for black ink and 5.8 ng ± 10% for color ink. In this example, a solid image recorded under the following conditions (i) and (ii) is defined as having a recording duty of 100%. (i) In the case of black ink, the condition is that one drop of ink weighing approximately 28 ng is applied to a unit area of ​​1 / 600 inch x 1 / 600 inch. (ii) In the case of color ink, four drops of ink, each weighing approximately 5.8 ng, are applied to a unit area of ​​1 / 600 inch x 1 / 600 inch.

[0067] After repeating the above cycle 10 times, a nozzle check pattern was recorded on one sheet of the inkjet recording device and visually inspected. After recording, the recording head was removed and any deposits around the ejection ports were observed under a microscope. The ink ejection stability was then evaluated according to the following evaluation criteria. A: There was no adhesion around the nozzle, and the nozzle check pattern was not disturbed. B: There was a small amount of adhesion around the ejection port, and the nozzle check pattern was slightly disturbed, but still within the usable level.

[0068] (Storage stability) Each ink was diluted 3,000 times with ion-exchange water to prepare samples. The absorption spectrum of the prepared sample was measured using a spectrophotometer to obtain the maximum absorbance (A0) in the wavelength range of 380 to 700 nm. The spectrophotometer used was a Hitachi U-3300. The ink was then placed in a sealed container and stored in an oven at 70°C for 14 days. After returning to 25°C, the absorption spectrum was measured using the same procedure as above to obtain the maximum absorbance (A1) in the wavelength range of 380 to 700 nm. The rate of change in absorbance before and after storage was calculated, and the storage stability of the ink was evaluated according to the following evaluation criteria. A: The rate of change in maximum absorbance was less than 2%. B: The rate of change in maximum absorbance was 2% or more and less than 5%. C: The rate of change in maximum absorbance was 5% or more.

[0069] TIFF2025185927000008.tif166170

[0070] The disclosure of this embodiment includes the following configurations. (Configuration 1) A water-based ink comprising a colorant and a resin containing a unit derived from biomass-derived acrylonitrile. (Configuration 2) The aqueous ink according to Configuration 1, wherein the content (mass %) of the acrylonitrile-derived units in the resin is 10 mass % or more and 60 mass % or less, based on the total mass of the resin. (Configuration 3) The resin further contains a unit derived from acrylic acid or methacrylic acid and has a carboxylic acid group in its molecule, 3. The aqueous ink according to claim 1, wherein at least a portion of the carboxylic acid groups are neutralized with an alkali. (Configuration 4) The resin is a water-soluble resin, The acid value of the water-soluble resin is 10 mgKOH / g or more and 200 mgKOH / g or less, 4. The water-based ink according to any one of configurations 1 to 3, wherein the weight-average molecular weight of the water-soluble resin is 5,000 or more and 20,000 or less. (Configuration 5) The coloring material is a pigment, 5. The aqueous ink according to any one of configurations 1 to 4, wherein the resin is a dispersant for dispersing the pigment. (Configuration 6) The resin forms resin particles, The cumulative 50% particle diameter (D 50 4. The aqueous ink according to any one of configurations 1 to 3, wherein the average particle diameter is 50 nm or more and 250 nm or less. (Configuration 7) The aqueous ink according to any one of Configurations 1 to 6, which is an inkjet ink. (Configuration 8) A substrate and an image provided on the surface of the substrate, 8. A printed matter, wherein the image is formed using the aqueous ink according to any one of configurations 1 to 7.

Claims

1. An aqueous ink comprising a colorant and a resin containing a unit derived from biomass-derived acrylonitrile.

2. 2. The aqueous ink according to claim 1, wherein the content (% by mass) of the acrylonitrile-derived unit in the resin is 10% by mass or more and 60% by mass or less, based on the total mass of the resin.

3. the resin further contains a unit derived from acrylic acid or methacrylic acid and has a carboxylic acid group in its molecule, 2. The aqueous ink according to claim 1, wherein at least a portion of the carboxylic acid groups are neutralized with an alkali.

4. the resin is a water-soluble resin, The acid value of the water-soluble resin is 10 mgKOH / g or more and 200 mgKOH / g or less, 2. The water-based ink according to claim 1, wherein the water-soluble resin has a weight average molecular weight of 5,000 or more and 20,000 or less.

5. the coloring material is a pigment, 2. The water-based ink according to claim 1, wherein the resin is a dispersant for dispersing the pigment.

6. the resin forms resin particles, The cumulative 50% particle diameter (D ５０ 2. The aqueous ink according to claim 1, wherein the average particle diameter of the particles is 50 nm or more and 250 nm or less.

7. 10. The aqueous ink according to claim 1, which is an inkjet ink.

8. A substrate and an image provided on a surface of the substrate, A printed matter, wherein the image is formed using the aqueous ink according to claim 1 .

Images