Aqueous ink and printed matter

Abstract

To provide an aqueous ink that employs biomass-derived material but enables recording of an image having scratch 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 styrene, 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 (hereinafter also referred to as "abrasion resistance") that prevent defects such as image damage or peeling due to contact during display or transportation, and maintain image quality. 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 abrasion 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 styrene. [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 abrasion resistance equal to or greater than that of images recorded with conventional inks prepared substantially without using biomass-derived materials. Furthermore, according to the present invention, it is possible to provide printed materials 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 record images with abrasion resistance equivalent to or greater than that of images recorded with conventional inks prepared substantially without biomass-derived materials. Specifically, they compared the characteristics of an image recorded with an ink containing a resin containing a unit derived from biomass-derived styrene with an image recorded with an ink containing a resin containing a unit derived from petroleum-derived styrene. 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 styrene. The ink of the present invention will be described in detail below.

[0011] (resin) The ink contains a resin containing a unit derived from biomass-derived styrene. 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 content (% by mass) of units derived from biomass-derived styrene in the resin is preferably 40% by mass or more, and more preferably 50% by mass or more and 70% by mass or less, based on the total mass of the resin. By using a resin in which the content of units derived from biomass-derived styrene falls within the above range, the scratch resistance of the image can be further improved.

[0013] The present inventors prepared an ink containing a resin with a content of units derived from biomass-derived styrene of 40% by mass or more, and an ink containing a resin with a content of units derived from petroleum-derived styrene of 40% by mass or more. They then compared the scratch resistance of images recorded with these inks. As a result, it was found that the ink containing a resin with a content of units derived from biomass-derived styrene of 40% by mass or more can record images exhibiting equal to or greater scratch resistance, even if the content of the units is lower. The carbon atom of biomass-derived styrene is an unstable radioactive carbon atom. 14 C, so it is a stable carbon atom 12 It is thought that resins containing units derived from biomass-derived styrene are more likely to adsorb to pigments composed of C. As a result, it is speculated that resins containing units derived from biomass-derived styrene have a stronger adsorption power to pigments, further improving the scratch resistance of images.

[0014] When a resin is used as a dispersant for dispersing a pigment, the lower the content of units derived from styrene in the resin, the more the ejection performance of the inkjet ink tends to improve. As described above, units derived from biomass-derived styrene can further improve the scratch resistance of images and the dispersion stability of pigments with a smaller amount than units derived from petroleum-derived styrene. Therefore, from the perspective of improving the ejection performance of the inkjet ink, using biomass-derived styrene is advantageous over using petroleum-derived styrene.

[0015] Biomass-derived styrene can be produced according to known methods using biomass as a raw material. For example, biomass-derived styrene can be obtained by deoxygenating biomass-derived cinnamic acid. Biomass-derived styrene can also be obtained by using biomass-derived benzene and ethylene. Biomass-derived benzene and ethylene can be produced by cracking bionaphtha obtained from vegetable waste oil or animal waste oil. Benzene and ethylene can also be produced from bioethanol. Furthermore, benzene and ethylene may be produced using 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 styrene. The other units are units formed by other monomers other than styrene. 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 acid value of the resin is preferably 10 mgKOH / g or more and 200 mgKOH / g or less. By using a resin with an acid value within the above range, it is possible to record an image with improved abrasion resistance. If the acid value of the resin is less than 10 mgKOH / g, the effect of improving abrasion resistance may be slightly reduced. On the other hand, if the acid value of the 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 abrasion resistance of the image may be slightly reduced.

[0020] The weight-average molecular weight of the resin is preferably 4,000 or more and 20,000 or less. By using a resin with a weight-average molecular weight within the above range, it is possible to record images with improved abrasion resistance. If the weight-average molecular weight of the resin is less than 4,000, the resin molecules may not easily entangle with each other within the image. This may result in a slight lack of film strength, and the effect of improving abrasion resistance may be reduced. On the other hand, if the weight-average molecular weight of the resin is more than 20,000, the viscosity of the ink may increase excessively, requiring a long time to form a film. This may result in a reduced effect of improving the abrasion resistance of the image immediately after recording.

[0021] 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)".

[0022] 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.

[0023] The water-soluble resin can be used as a dispersant for dispersing the pigment. The acid value of the water-soluble resin is preferably 100 mgKOH / g or more and 180 mgKOH / g or less. Using a water-soluble resin with an acid value within the above range as a dispersant can further improve dispersion stability and ejection performance. If the acid value of the water-soluble resin is less than 100 mgKOH / g, it will have a strong adsorption force to the pigment, making it somewhat difficult to redisperse the ink after drying. This may result in a slight decrease in ink ejection performance. On the other hand, if the acid value of the water-soluble resin is greater than 180 mgKOH / g, it may be more likely to peel from the pigment, resulting in a slight decrease in dispersion stability. The acid value of the water-soluble resin can be controlled by adjusting the ratio of the carboxylic acid group-containing monomer used in synthesizing the resin.

[0024] The weight-average molecular weight of the water-soluble resin is preferably 5,000 or more and 12,000 or less. If the weight-average molecular weight of the water-soluble resin is less than 5,000, its function as a dispersant may be slightly reduced. On the other hand, if the weight-average molecular weight of the water-soluble resin is more than 12,000, its adsorption to the pigment may be so strong that the ink ejection performance may be slightly reduced.

[0025] The preferred ranges of the acid value and the weight-average molecular weight of the resin are those when biomass-derived styrene is used, and are different from those when petroleum-derived styrene is used. The reason for the difference in the preferred ranges between the two is not entirely clear, but as mentioned above, it is presumed that the difference in carbon atoms has an effect.

[0026] 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 specific surface area increases, which increases the number of interfaces when redispersing dried ink. This may lead to a decrease in the redispersibility of the ink. On the other hand, if the average particle diameter of the resin particles exceeds 250 nm, unevenness caused by the resin particles may be easily formed on the image surface. Then, stress may be easily transmitted by being caught on the unevenness formed, which may reduce the effect of improving abrasion resistance.

[0027] The cumulative 50% particle size (D 50 ) is the cumulative 90% particle diameter (D 90 ) is preferably 0.6 to 0.8 times. If the ratio is less than 0.6 times, the particle size distribution will be broad, and the arrangement of the resin particles in the image will tend to become irregular. This may result in insufficient film strength, and the effect of improving the scratch resistance of the image may be reduced.

[0028] 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.

[0029] The preferred range of the weight average molecular weight is different between a resin containing a unit derived from biomass-derived styrene and a resin containing a unit derived from petroleum-derived styrene. The molecular chain of the resin containing a unit derived from biomass-derived styrene 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 styrene have a higher specific gravity and are more likely to settle than resin particles formed from a resin containing units derived from petroleum-derived styrene. 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 styrene is smaller than the weight-average molecular weight of a resin containing units derived from petroleum-derived styrene.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 styrene and acrylic acid or methacrylic acid. Furthermore, the resin used as a dispersant is more preferably a copolymer of biomass-derived styrene, 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 with excellent dispersibility, which is less susceptible to pigment aggregation and precipitation. 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 content (mass%) of the dispersant is preferably 0.1 to 0.5 times the mass ratio of the content (mass%) of the pigment.

[0035] In the resin used as a dispersant, the content (mass%) of units derived from acrylic acid or methacrylic acid relative to the content (mass%) of units derived from biomass-derived styrene is preferably 0.1 to 1.0 times, in mass ratio, and more preferably 0.2 to 0.4 times. By achieving this mass ratio, even when the ink is continuously ejected, ejection defects due to kogation and deposits adhering within the ink flow path and near the ejection orifice are less likely to occur, thereby improving the ejection stability of the ink. For this reason, resins with the above mass ratio are suitable as dispersants for inkjet inks, particularly thermal-type inkjet inks.

[0036] 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.

[0037] (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.

[0038] 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.

[0039] 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.

[0040] When the above-mentioned resin is used as a dispersant for dispersing the pigment, it is preferable to use carbon black, azo, phthalocyanine, or quinacridone as the pigment, since this further improves dispersion stability.

[0041] (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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] (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.

[0046] <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.

[0047] 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.

[0048] 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]

[0049] 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.

[0050] <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).

[0051] (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)

[0052] (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).

[0053] <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 αMSt: α-methylstyrene AN: Acrylonitrile BA: Butyl acrylate AA: Acrylic acid V-59: 2,2'-azobis(2-methylbutyronitrile) (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0054] The biomass-derived styrene used was obtained by decarboxylating biomass-derived cinnamic acid, heating it in an oil bath, and distilling and separating it under a pressure condition of 1 Torr.

[0055] TIFF2025185928000001.tif114170

[0056] <Preparation of resin particles> (Resin particles 1 and 2) The types and amounts (units: parts) of monomers, emulsifiers, and 150.0 parts of ion-exchanged water shown in Table 2 were mixed using a homogenizer (product name "T50D Ultra Turrax," manufactured by IKA) to obtain a mixture. 50.0 parts of the mixture was placed in a flask equipped with a stirrer, nitrogen inlet tube, reflux condenser, and thermometer, and the temperature was raised to 70°C while stirring under a nitrogen atmosphere. The remainder of the mixture and a liquid obtained by dissolving 1.0 part of potassium persulfate in 20.0 parts of ion-exchanged water were added dropwise over 2 hours. After heating to 80°C, the mixture was stirred for 2 hours to allow the reaction to proceed, yielding a dispersion. The pH of the resulting dispersion was adjusted to 8.5 by adding 1 mol / L aqueous potassium hydroxide solution, and an appropriate amount of ion-exchanged water was added to obtain an aqueous dispersion of resin particles 1 and 2 with a resin particle content of 20.0%. The average particle diameters of resin particles 1 and 2 are shown in Table 2. The abbreviations in Table 2 are defined below. St: Styrene AN: Acrylonitrile BA: Butyl acrylate AA: Acrylic acid NS-5S: Emulsifier (product name "Eleminol NS-5S", manufactured by Sanyo Chemical Industries, Ltd.)

[0057] TIFF2025185928000002.tif41170

[0058] <Preparation of pigment dispersion> (Pigment dispersions 1 to 18) 37.5 parts of a liquid containing the type of water-soluble resin shown in Table 3, 15.0 parts of the type of pigment shown in Table 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 zirconia beads with a diameter of 0.3 mm was used to carry out a dispersion treatment for 3 hours with water cooling. The mixture was centrifuged to remove coarse particles, and then pressure-filtered through a microfilter (manufactured by Fujifilm) with a pore size of 3.0 μm to obtain pigment dispersions 1 to 18, each with a pigment content of 10.0% and a water-soluble resin content of 3.0%.

[0059] <Rating (1)> (dispersion stability) The prepared pigment dispersions were placed in sealed containers and stored in a thermostatic chamber at 70°C for 60 days before being removed. After cooling to room temperature, the average particle diameter (D 50 (nm), D 90 The particle diameter (nm) and the number of particles with a particle diameter of 0.5 μm or more and less than 5.0 μm were measured. The dispersion stability of the pigment in the pigment dispersion was then evaluated according to the following evaluation criteria. The results are shown in Table 3. A:D 50 Rate of change of (nm), D 90 The rate of change in particle size (nm) and the rate of change in the number of particles with a particle size of 0.5 μm or more and less than 5.0 μm were both 5% or less. B:D 50 Rate of change of (nm), D 90 At least one of the rate of change in the particle diameter (nm) and the rate of change in the number of particles having a particle diameter of 0.5 μm or more and less than 5.0 μm exceeded 5%.

[0060] (Average particle size of pigment (D 50 (nm), D 90 (nm)) The pigment dispersion was diluted 10,000 times (by mass) with pure water, and the average particle diameter (D 50 (nm), D 90 (nm)) was measured under the following measurement conditions: [Measurement conditions] Setzero:30s Measurement time: 120 seconds Measurement count: 3 times Particle refractive index: 1.8 Solvent: Water Filter: Standard Sensitivity: Standard

[0061] (Method for measuring the number of particles with a particle diameter of 0.5 μm or more and less than 5.0 μm) The pigment dispersion was diluted 10,000 times (by mass) with pure water, and then the number of particles with a particle size of 0.5 μm or more and less than 5.0 μm was measured using a particle size distribution analyzer (product name "Accusixer780APS", manufactured by Particle Sizing System). The measurement conditions are as follows: [Measurement conditions] Measurement time: 60 seconds Number of channels: 128 ·Flow rate: 60mL / min Sample loop capacity: 1 mL First dilution ratio: 30 times Second stage dilution ratio: 40x

[0062] TIFF2025185928000003.tif149170

[0063] <Ink Preparation> (Ink 1-7) 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 7. ·Cabojet250C: 20.0 copies Liquid containing water-soluble resins of the types shown in Table 4 or aqueous dispersion of resin particles: 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: 38.8 parts

[0064] "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).

[0065] TIFF2025185928000004.tif69170

[0066] (Ink 8~23) 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 8 to 23. 30.0 parts of pigment dispersion of the type shown in Table 5 Liquid containing water-soluble resin of the type shown in Table 5: 15.0 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: 36.3 parts

[0067] TIFF2025185928000005.tif130170

[0068] <Evaluation (2)> The following items were evaluated, and the results are shown in Table 6.

[0069] (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.

[0070] (Abrasion resistance) Each ink cartridge was filled with the prepared ink and loaded 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 the conditions of depositing one ink droplet of 5 pL per droplet in a unit area of ​​1 / 1,200 inch x 1 / 1,200 inch was defined as 100%. Using the above 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 solid image was left in a heated environment to allow the resin to sufficiently form a film. Thereafter, a friction test was performed using a Gakushin-type testing machine (product name: "Abrasion Resistance Tester" manufactured by Imoto Machinery Co., Ltd.) under conditions of 20 reciprocating strokes at a load of 300 g. The image after the friction test was visually inspected, and the abrasion resistance of the image was evaluated according to the following evaluation criteria. A: There were no scratches in the image, or scratches that were not visible unless you looked closely. B: Scratches on the image could be seen from a distance, but the underlying recording medium was not visible. C: The image had scratches and the underlying recording medium was visible.

[0071] (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.

[0072] 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.

[0073] TIFF2025185928000006.tif177170

[0074] 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 styrene. (Configuration 2) The aqueous ink according to Configuration 1, wherein the content (mass %) of the styrene-derived units in the resin is 40 mass % or more 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 100 mgKOH / g or more and 180 mgKOH / g or less, 4. The aqueous ink according to any one of claims 1 to 3, wherein the weight average molecular weight of the water-soluble resin is 5,000 or more and 12,000 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 aqueous ink according to Configuration 5, wherein the content (mass %) of the dispersant is 0.1 to 0.5 times the mass ratio of the content (mass %) of the pigment. (Configuration 7) 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 8) The aqueous ink according to any one of Configurations 1 to 7, which is an inkjet ink. (Configuration 9) A substrate and an image provided on the surface of the substrate, 9. A printed matter, wherein the image is formed using the aqueous ink according to any one of configurations 1 to 8.

Claims

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

2. The aqueous ink according to claim 1 , wherein the content (mass %) of the styrene-derived units in the resin is 40 mass % or more 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 100 mgKOH / g or more and 180 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 12,000 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 aqueous ink according to claim 5 , wherein the content (mass %) of the dispersant is 0.1 to 0.5 times the content (mass %) of the pigment in terms of mass ratio.

7. 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.

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

9. 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 .

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