Water-based pigment dispersions, water-based inkjet inks, and drying films

Abstract

The aqueous pigment dispersion provided by this invention is an environmentally friendly water-based inkjet ink that can stabilize and highly disperse pigments, and record images with excellent durability, gloss, color development, and adhesion to various printing substrates. The aqueous pigment dispersion of this invention contains: pigment, water, a water-soluble organic solvent, and a polymeric dispersant for dispersing the pigment; wherein the polymeric dispersant contains: a constituent unit (i) derived from at least one of (meth)acrylic acid and itaconic acid, and a constituent unit (ii) derived from (meth)acrylic acid esters derived from biological materials, such as ethyl (meth)acrylic acid; and is a polymer with an acid value of 30-250 mgKOH / g, a constituent unit (ii) content of 50% by mass or more, a number average molecular weight of 1,000-30,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 2.5 or less, and at least a portion of the carboxyl groups being neutralized by alkali.

Description

Technical Field

[0001] This invention relates to aqueous pigment dispersions, aqueous inkjet inks, and dried films. Prior Technology

[0002] Inkjet printing, due to its high functionality, is widely used in personal, office, commercial, record-keeping, color display, and color photography applications. Furthermore, in recent years, its application scope has been expanding, from familiar consumer inkjet printers for office use and wide-format inkjet printers for large-format printing to inkjet printers for industrial applications. Because inkjet printing does not require printing plates, it is suitable as a printing method for producing a variety of industrial printed materials in small quantities. In addition, from an environmental perspective, proposals for inkjet printing using water-based inks are gaining popularity.

[0003] Industrial applications include: signs and directional signs, outdoor advertising, facility signage, displays, point-of-purchase (POP) advertising, public transport advertising, packaging, containers, and labels. Printing substrates (recording media) used for these applications include: paper media such as paper, cardboard, photo paper, and inkjet paper; plastic media such as polyvinyl chloride, polyolefins, polyester, and nylon; and fabrics such as cotton, polyester fabric, nylon fabric, and non-woven fabric. Furthermore, in industrial applications, the mainstream is on-demand printing that does not require printing plates and demands high-speed printing adaptability. Moreover, images recorded using water-based inkjet inks containing dyes lack durability such as water resistance or lightfastness; therefore, water-based inkjet inks containing pigments are used instead.

[0004] Therefore, in order to record printed images with improved durability, there are proposals for inkjet inks containing acrylic or amine ester adhesives that can form a film (Patent Documents 1 and 2). Furthermore, since water-based pigment inkjet inks require stable and micro-dispersed pigments, there are proposals for pigment dispersions that use surfactants or polymeric dispersants to stabilize and micro-disperse pigments over time, and inkjet inks using these dispersions (Patent Document 3). [Previous Technical Documents] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent No. 4157868 [Patent Document 2] Japanese Patent Publication No. 2009-515007 [Patent Document 3] International Publication No. 2013 / 008691 Summary of the Invention

[0006] (The problem the invention aims to solve)

[0007] However, even inkjet inks using the pigment dispersions proposed in Patent Documents 1 to 3 still struggle to record images with excellent durability, such as adhesion and abrasion resistance.

[0008] However, given the current trends of global warming, carbon dioxide emissions, resource issues, and marine plastic pollution, the importance of energy-saving strategies, recycling strategies, and environmentally friendly technologies such as environmentally friendly materials is gradually increasing. In this context, the dispersant conventionally used in water-based inkjet inks or water-based pigment dispersions to disperse pigments is a polymeric dispersant synthesized from raw materials such as monomers derived from petroleum materials. That is, images recorded using conventional water-based inkjet inks are formed from materials derived from petroleum materials, and therefore may not be suitable for environmentally friendly technologies. While printing substrates such as containers or labels made from biodegradable plastics such as polylactic acid or polyhydroxyalkanoates are suitable for inkjet printing, there is a challenge that images recorded on these substrates are not suitable for environmentally friendly technologies.

[0009] This invention was made in view of the problems existing in the prior art. Its objective is to provide an aqueous pigment dispersion that can be formulated to produce an environmentally friendly water-based inkjet ink that exhibits excellent pigment stability and high micro-dispersion, and can record images with superior durability, gloss, color development, and adhesion to various printing substrates. Furthermore, this invention aims to provide an aqueous inkjet ink using the aqueous pigment dispersion, and a dried film formed using the aqueous inkjet ink. (Technical means to solve the problem)

[0010] That is, according to the present invention, an aqueous pigment dispersion as shown below is provided. [1] An aqueous pigment dispersion comprising: pigment, water, water-soluble organic solvent, and a polymeric dispersant for dispersing the pigment; wherein the polymeric dispersant comprises: a constituent unit (i) derived from at least one of (meth)acrylic acid and itaconic acid, and a constituent unit (ii) derived from (meth)acrylate derived from biological materials, and is a polymer with an acid value of 30 to 250 mg KOH / g, a content of the constituent unit (ii) of 50% by mass or more, a number average molecular weight of 1,000 to 30,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 2.5 or less, and at least a portion of the carboxyl groups being neutralized by alkali; the (meth)acrylate derived from biological materials is selected from at least one of the group consisting of: ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate. [2] As described in [1] above, the aqueous pigment dispersion is a polymer that satisfies the following requirements (1) to (4). [Requirement (1)]: An AB block copolymer containing polymer chains A1 and B1, comprising more than 90% by mass of constituent units derived from methacrylic acid monomers. [Requirement (2)]: The above polymer chain A1 system It contains more than 80% by mass of the constituent units (ii-a) derived from methacrylates derived from biological materials, and is... The number average molecular weight is 1,000~10,000. Water-insoluble polymer blocks with a molecular weight distribution of less than 1.6. [Requirement (3)]: The above polymer chain B1 system Contains a building block (ib) derived from methacrylic acid, and Contains 40-90% by mass of constituent units (ii-b) derived from methacrylates derived from biological materials, and is Acid value of 50~260mgKOH / g The number average molecular weight is 1,000~10,000. A polymer block in which at least a portion of the carboxyl group is neutralized by a base. [Requirement (4)]: The number average molecular weight is 2,000 to 20,000, and the molecular weight distribution is below 1.6. [3] As described in [2] above, the aqueous pigment dispersion wherein the methacrylate derived from the biomaterial is selected from at least one of the group consisting of: ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate and octadecyl methacrylate. [4] The aqueous pigment dispersion described in any one of [1] to [3] above, wherein the base system that neutralizes at least a portion of the carboxyl group is selected from at least one of the group consisting of: ammonia, dimethylamine ethanol, 2-amino-1-propanol, sodium hydroxide, potassium hydroxide, lithium hydroxide, straight-chain aliphatic amines with 6 to 22 carbon atoms, branched aliphatic amines with 6 to 22 carbon atoms, and unsaturated aliphatic amines with 6 to 22 carbon atoms. [5] The aqueous pigment dispersion described in any of [1] to [4] above, wherein the pigment content is 5 to 60% by mass, the water content is 20 to 80% by mass, the water-soluble organic solvent content is less than 30% by mass, and the polymeric dispersant content is 0.5 to 20% by mass.

[0011] Furthermore, according to the present invention, the following water-based inkjet ink is provided. [6] An aqueous inkjet ink contains an aqueous pigment dispersion as described in any one of [1] to [5] above. [7] As described in [6] above, water-based inkjet inks further contain adhesive components. [8] As described in [7] above, the water-based inkjet ink contains a polymer that satisfies the following requirements (5) to (9). [Requirements (5)]: An AB block copolymer containing polymer chains A2 and B2, comprising more than 90% by mass of constituent units derived from methacrylic acid monomers. [Requirement (6)]: The above polymer chain A2 system It contains more than 80% by mass of constituent units derived from methacrylates derived from biological materials, and is... The number of molecules with an average molecular weight of 10,000 to 30,000 Water-insoluble polymer blocks with a molecular weight distribution of less than 1.6. [Requirement (7)]: The above polymer chain B2 system Contains building blocks derived from methacrylic acid, and Contains 40-90% by mass of constituent units derived from bio-methacrylates derived from biological materials, and is Acid value of 50~150mgKOH / g The number of molecules with an average molecular weight of 5,000 to 20,000 A polymer block in which at least a portion of the carboxyl group is neutralized by a base. [Requirements (8)]: The number average molecular weight is 15,000 to 50,000, and the molecular weight distribution is below 1.6. [Requirements (9)]: The number of particles with an average diameter of 10~200nm. [9] As described in [8] above, the water-based inkjet ink wherein the methacrylate derived from the biomaterial is selected from at least one of the group consisting of: ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate and octadecyl methacrylate.

[0012] Furthermore, according to the present invention, a dried film as shown below is provided.

[10] A dried film is a film-like dried product of the aqueous inkjet ink described in [8] or [9] above. (Compared to the effectiveness of previous technologies)

[0013] According to the present invention, an aqueous pigment dispersion is provided, which is an environmentally friendly water-based inkjet ink capable of producing stable and highly micro-dispersed pigments and recording images with excellent durability, gloss, color development, and adhesion to various printing substrates. Furthermore, according to the present invention, an aqueous inkjet ink using the aqueous pigment dispersion and a dried film formed using the aqueous inkjet ink are also provided. Implementation

[0014] <Aqueous Pigment Dispersion> The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. Unless otherwise stated, all physical property values ​​in this specification refer to values ​​at room temperature (25°C). Hereinafter, "aqueous pigment dispersion" will be abbreviated as "pigment dispersion," and "aqueous inkjet ink" will be abbreviated as "ink."

[0015] The aqueous pigment dispersion of the present invention comprises: pigment, water, water-soluble organic solvent, and a polymeric dispersant for dispersing the pigment. Furthermore, the polymeric dispersant comprises: a constituent unit (i) derived from at least one of (meth)acrylic acid and itaconic acid, and a constituent unit (ii) derived from (meth)acrylic acid derived from biological materials, and is a polymer with an acid value of 30-250 mg KOH / g, a constituent unit (ii) content of 50% by mass or more, a number average molecular weight of 1,000-30,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 2.5 or less, and at least a portion of its carboxyl groups being neutralized by alkali. The detailed description of the aqueous pigment dispersion of the present invention will follow.

[0016] (pigment) Pigment systems can use either organic or inorganic pigments. Examples of organic pigment systems include: soluble azo pigments, insoluble azo pigments, phthalocyanine pigments, quinacrine pigments, isoindoline ketone pigments, isoindoline pigments, perylene pigments, perylene ketone pigments, and dichlorodiphenyl ether pigments. Pigments include anthraquinone pigments, dianthraquinone pigments, anthraquinone pigments, anthraquinone pigments, anthrone pigments, indanthrene pigments, flavonoid pigments, pyranthrone pigments, and pyrrolopyrroledione pigments. Inorganic pigments include, for example, titanium dioxide, iron oxide, antimony pentoxide, zinc oxide, silicon dioxide, cadmium sulfide, calcium carbonate, barium carbonate, barium sulfate, clay, talc, lead yellow, carbon black, aluminum flakes, mica pigments, bamboo charcoal, coconut shell activated carbon, crushed seashells, rosin, and coal, etc.

[0017] If superior pigments are indicated by pigment index numbers (CI), examples include: CI pigment blue 15:3, 15:4, 15:6; CI pigment red 122, 176, 254, 269, 291; CI pigment violet 19, 23; CI pigment yellow 74, 150, 155, 180; CI pigment green 36, 58; CI pigment orange 43, 71; CI pigment black 7; CI pigment white 6, etc., which are commonly used pigments in inkjet inks.

[0018] The number-average particle size (primary particle size) of organic pigments is preferably below 150 nm. The number-average particle size (primary particle size) of inorganic pigments is preferably below 300 nm. By using pigments with a number-average particle size within the above range, the optical density, chroma, color rendering, and print quality of the recorded image can be improved, and pigment deposition in the ink can be moderately suppressed. The number-average particle size of the pigment can be measured, for example, using an electron microscope or a light scattering particle size analyzer.

[0019] Pigments can also be surface-treated using surface-treatment agents such as polymeric dispersants, silane coupling agents, inorganic substances (silicon dioxide, zirconium dioxide, sulfuric acid, etc.), and pigment derivatives (synergists). For example, these surface-treatment agents can be added or coexisted when synthesizing pigments, pigmenting, or micronizing pigments. Furthermore, quinacrine pigments can also be used as complexes such as mixed crystals of dissimilar pigments or solid solution pigments. Pigments can also be treated with polymeric dispersants or encapsulated. Additionally, pigments obtained from raw materials derived from biological materials can also be used. For example, by using succinic acid obtained from sugarcane, quinacrine pigments such as Pigment Red 122 or Pigment Violet 19 can be obtained.

[0020] (Liquid medium) Aqueous pigment dispersions are liquid media containing water and water-soluble organic solvents as the dispersion medium for pigments. Examples of water-soluble organic solvents that can be used include: alcohol-based solvents, glycol-based solvents, glycol ethers, amide-based solvents, carbonate-based solvents, and other polar solvents.

[0021] Examples of alcohol-based solvents include methanol, ethanol, isopropanol, propanol, butanol, and isobutanol. Examples of glycol-based solvents include ethylene glycol, propylene glycol, and glycerol. Examples of glycol ethers include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, ethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, 1,3-butanediol, and 3-methoxy-3-methyl-1-butanol. Examples of acetylamine-based solvents include: dimethylformamide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropionic acid, and 3-butoxy-N,N-dimethylpropionic acid. Examples of carbonate-based solvents include: ethyl carbonate, propyl carbonate, and dimethyl carbonate. Other polar solvents include: dimethyl sulfoxide, tetramethylurea, and dimethylimidazolinedione.

[0022] Water-soluble organic solvents are preferred, such as solvents derived from biological materials, recycled solvents, biodegradable solvents, and green solvents. Specifically, examples include: ethanol obtained through fermentation or saccharification of sugarcane, corn, and cellulose materials; 1,3-butanediol and glycerol derived from natural extracts; biodegradable 3-methoxy-3-methyl-1-butanol; ethylene glycol, propylene glycol, and their derivatives, which are recycled solvents for various materials such as plastics.

[0023] The polymeric dispersant and the binder components described later are preferably manufactured by solution polymerization using water-soluble organic solvents used in water-based pigment dispersions or water-based inkjet inks. If these water-soluble organic solvents are used as polymerization solvents, the polymer solution obtained from polymerization can be directly used to formulate water-based pigment dispersions or water-based inkjet inks, simplifying the process.

[0024] (Polymer dispersant) The polymeric dispersant is a polymer containing a constituent unit (i) derived from at least one of (meth)acrylic acid and itaconic acid. Itaconic acid is a monomer obtained by fermentation and is therefore an environmentally friendly material. By using these monomers, carboxyl groups can be introduced into the polymer used as a polymeric dispersant. Furthermore, by neutralizing and ionizing the introduced carboxyl groups with an alkali, the polymer (polymeric dispersant) can be dissolved in water.

[0025] The amount of carboxyl groups in a polymer is determined by its acid value. Specifically, the acid value of the polymer used as a polymeric dispersant is 30-250 mg KOH / g, preferably 50-230 mg KOH / g. If the acid value is less than 30 mg KOH / g, the polymer is not easily soluble in water. On the other hand, if the acid value exceeds 250 mg KOH / g, the polymer becomes too hydrophilic, making it prone to detaching from the pigment, resulting in reduced pigment dispersion stability or reduced water resistance of the recorded image (dried film).

[0026] The polymeric dispersant is a polymer containing a constituent unit (ii) derived from (meth)acrylates derived from biological materials. In this specification, "biologically derived (meth)acrylates" refers to "(meth)acrylates derived from alcohols derived from biological materials." That is, "biologically derived (meth)acrylates" are (meth)acrylates synthesized using alcohols derived from biological materials as materials, where the oxygen-containing ester residues other than the (meth)acrylic group are alcohol residues derived from biological materials.

[0027] Examples of alcohols derived from biological materials include: ethanol, methanol, isopropanol, isobutanol, and lactic acid obtained through fermentation; glucose, glycerol, isosorbide, and glyceryl methylamine, a derivative of glycerol, obtained from the decomposition of sugars, starches, and fats; benzyl alcohol and phenylethyl alcohol, extracted from natural sources to become flavoring ingredients; tetrahydrofurfural, a hydrogen reduction product of furfural, obtained from corn cobs; and octanol, decanol, and dodecanol, obtained from palm oil or coconut oil, etc. Tetradecyl alcohol, hexadecyl alcohol, heptadecanol, stearyl alcohol, oleyl alcohol, and docosyl alcohol; 3-pentadecanol, 3-pentadecanol monoene, and 3-pentadecanol diene obtained from cashew nuts, etc.; sinigrin, coniferyl alcohol, and p-coumarol, which are components of lignin; geraniol, lecithinol, nerol, menthol, terpineol, and terpineol obtained from plant refining; pine resin; isothiols obtained from camphor in pine resin, etc., mainly monohydric alcohols obtained from plants, etc.

[0028] (Meth)acrylates derived from biological materials are esters of alcohols and (meth)acrylic acid derived from the aforementioned biological materials. Examples include: methyl methacrylate, ethyl methacrylate, glyceryl mono(meth)acrylate, benzyl methacrylate, phenethyl methacrylate, tetrahydrofurfuryl methacrylate, octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, heptadecanyl methacrylate, stearyl methacrylate, isomethacrylate, etc.

[0029] Methacrylates derived from biological materials are obtained from biological materials and can therefore be distinguished from methacrylates derived from petroleum materials. Furthermore, compounds derived from petroleum materials do not contain carbon-14 (14C), an isotope of carbon, while compounds derived from biological materials, especially plant materials, do contain carbon-14 (14C). Therefore, the presence or absence of carbon-14 (14C) can be used to determine whether a methacrylate is derived from biological materials. Methods for determining carbon-14 include, for example, beta-ray diffraction and accelerator mass spectrometry (AMS). In particular, environmental materials are also specified in biomass concentration testing standards such as ASTM D6866, European standard CEN16137, and ISO international standard ISO16620-2.

[0030] In the polymer used as a polymeric dispersant, the content of constituent unit (ii) is 50% by mass or more. By having a constituent unit (ii) content of 50% by mass in the polymer, it can be used as an environmentally friendly polymeric dispersant, and images and printed materials formed by inks containing this polymer as a polymeric dispersant can be considered environmentally friendly printed materials, etc.

[0031] The biomass of a polymer can be calculated from the percentage of alcohol residues derived from biological materials in the total carbon number of the monomers constituting the polymer used as a polymeric dispersant. For example, in the case of ethyl acrylate (total carbon number = 5), the number of ethanol residues derived from biological materials is 2, so the biomass is "2 ÷ 5 × 100 = 40%". Similarly, the calculated optimal biomass of (meth)acrylates is as follows: ethyl methacrylate 33.3%, tetrahydrofurfuryl acrylate 62.5%, tetrahydrofurfuryl methacrylate 55.5%, isobutyl acrylate 76.9%, isobutyl methacrylate 71.4%, octyl acrylate 72.7%, octyl methacrylate 66.6%, lauryl acrylate 80%, lauryl methacrylate 75%, tridecyl acrylate 81.3%, tridecyl methacrylate 76.5%, tetradecyl acrylate 82.4%, tetradecyl methacrylate 77.8%, hexadecyl acrylate 84.2%, hexadecyl methacrylate 80.0%, heptadecanyl acrylate 85.0%, heptadecanyl methacrylate 81.0%, stearyl acrylate 85.7%, and stearyl methacrylate 81.8%.

[0032] The polymer used as a polymeric dispersant may also contain constituent units other than those in (i) and (ii), such as constituent units derived from free radical polymerizable monomers (other monomers) derived from petroleum materials. Other monomer systems include, for example, ethylene monomers such as styrene and vinyltoluene; (meth)acrylic monomers, etc. Examples of monofunctional (meth)acrylate monomers include: methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, tridecayl, hexadecyl, octadecyl, isostearyl, docosyl, cyclohexyl, trimethylcyclohexyl, tributylcyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, nonylphenoxyethyl, isopropyl, dicyclopentyl, dicyclopentenyl, dicyclopentenoxyethyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 4-hydroxybutyl, dimethylaminoethyl, diethylaminoethyl, polyethylene glycol, polypropylene glycol, polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether, poly(ε-caprolactone), polydimethylsiloxane, etc. Among these, monomers with polyalkylene glycol chains are preferred because polyalkylene glycol chains are biodegradable and therefore environmentally friendly. The preferred polymer system used as a polymeric dispersant is substantially composed only of the aforementioned constituent units (i) and (ii).

[0033] The polymeric dispersant is a polymer with a number average molecular weight (Mn) of 1,000 to 30,000, preferably 2,000 to 25,000, and more preferably 3,000 to 20,000. If the Mn of the polymer is less than 1,000, it is easy to detach from the pigment, resulting in reduced dispersion stability of the pigment. On the other hand, if the Mn of the polymer exceeds 30,000, the viscosity of the pigment dispersion is too high, and the pigment particles are easily adsorbed and aggregated. In addition, the "number average molecular weight (Mn)" and "weight average molecular weight (Mn)" in this specification are polystyrene conversion values ​​measured using a gel permeation chromatography (GPC) analyzer.

[0034] The polymeric dispersant is a polymer with a molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) of 2.5 or less, preferably 2.0 or less, and more preferably 1.5 or less. If the molecular weight distribution (PDI) exceeds 2.5, the dispersibility of the pigment decreases. The molecular weight of the obtained polymer can be integrated or its structure controlled using living radical polymerization. By integrating the molecular weight of the polymer, the number of high-molecular-weight polymers and low-molecular-weight polymers can be reduced, resulting in a higher concentration of polymer chains that contribute to pigment dispersibility, which is preferable.

[0035] The polymeric dispersant is a polymer in which at least a portion of the carboxyl groups derived from (meth)acrylic acid or itaconic acid are neutralized by a base. Because at least a portion of the carboxyl groups are neutralized and ionized, the polymer readily bonds to and dissolves in water.

[0036] Examples of alkali-based compounds include: ammonia; organic amines such as triethylamine, dimethylamine ethanol, diethanolamine, triethanolamine, aminomethylpropanol, polyethylene glycol, and polypropylene glycol monoamine; organic monoamines derived from biological materials such as cocoylamine, octylamine, dodecylamine, stearylamine, oleylamine, and dimethyloctylamine; and alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide.

[0037] In terms of environmental friendliness, the preferred types are those free of organic matter and highly volatile ammonia; aminomethylpropanol derived from amino acids; dimethylamine ethanol, octylamine, and dodecylamine obtained from plants, etc.; and alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide. Furthermore, preferred alkali types include: ammonia, dimethylamine ethanol, 2-amino-1-propanol, sodium hydroxide, potassium hydroxide, lithium hydroxide, straight-chain aliphatic amines with 6-22 carbon atoms, branched aliphatic amines with 6-22 carbon atoms, and unsaturated aliphatic amines with 6-22 carbon atoms.

[0038] The polymer system using the pigment dispersion can be manufactured according to conventional methods. Specifically, it is preferably synthesized by solution polymerization using a water-soluble organic solvent used in pigment dispersions. For example, an azo-based polymerization initiator or a peroxide-based polymerization initiator can be used, and polymerization can be carried out by dripping the monomer into the water-soluble organic solvent or by bulk loading. During polymerization, chain transfer agents such as thiols or methyl bromide acrylate can also be used to adjust the molecular weight of the obtained polymer. Furthermore, to consolidate the molecular weight of the obtained polymer, it can also be synthesized using living radical polymerization. Examples of living radical polymerization methods include: atom transfer radical polymerization; NMP method using nitrile radicals, etc.; reversible addition-fragmentation chain transfer polymerization using thioesters or thiocarbonates, etc.; TEP method using organic tellurium as an initiator; iodine transfer polymerization using iodine compounds as initiators; reversible transfer catalyst polymerization or reversible catalyst-mediated polymerization using inorganic / organic catalysts; chain transfer polymerization using cobalt catalysts, etc.

[0039] The preferred polymeric dispersant is a polymer that meets the following requirements (1) to (4).

[0040] [Requirement (1)]: An AB block copolymer containing polymer chains A1 and B1, comprising more than 90% by mass of constituent units derived from methacrylic acid monomers. [Requirement (2)]: polymer chain A1 system It contains more than 80% by mass of methyl methacrylate-derived constituent units (ii-a) derived from biological materials, and is... The number average molecular weight is 1,000~10,000. Water-insoluble polymer blocks with a molecular weight distribution of less than 1.6. [Requirement (3)]: polymer chain B1 system Contains methyl methacrylate-derived building blocks (ib), and Contains 40-90% by mass of constituent units (ii-b) derived from methacrylates derived from biological materials, and is Acid value of 50~260mgKOH / g The number average molecular weight is 1,000~10,000. A polymer block in which at least a portion of the carboxyl group is neutralized by a base. [Requirement (4)]: The number average molecular weight is 2,000 to 20,000, and the molecular weight distribution is below 1.6.

[0041] The polymeric dispersant is an AB block copolymer containing polymer chain A1 (hereinafter also referred to as "A1 chain" or simply "A chain") and polymer chain B1 (hereinafter also referred to as "B1 chain" or simply "B chain"). The A1 chain is a water-insoluble polymer block, and the B1 chain is a water-soluble polymer block in which at least a portion of the carboxyl groups derived from methacrylic acid are neutralized by alkali.

[0042] The A1 chain is a water-insoluble polymer block, thus exhibiting high hydrophobicity and readily interacting with water-insoluble pigments. Therefore, the A1 chain can encapsulate the pigment by adsorbing or accumulating on it via hydrogen bonding. Furthermore, the high molecular weight of the A1 chain means it is unlikely to detach from the pigment. Additionally, because the A1 chain adsorbs onto the pigment while the B1 chain dissolves in water, the micro-dispersed pigments exhibit steric repulsion, maintaining their micro-dispersion over a long period. Moreover, since there is less free or dissolved polymeric dispersant in the liquid medium, or even if free A1 chains remain water-insoluble and form particles, the ejection stability of water-based inkjet inks can be improved, providing inks suitable for high-speed printing.

[0043] B1 is a water-soluble polymer block. Because the polymeric dispersant adsorbs onto the pigment, even when the ink containing this dispersant is dried using an inkjet printhead or similar method, the dispersant does not easily detach from the adsorbed pigment. Therefore, there is almost no pigment aggregation or the formation of a film from the detached dispersant, resulting in excellent redispersibility. It can be easily returned to a dispersed state by adding an aqueous liquid medium.

[0044] (Requirement (1)) The polymeric dispersant is an AB block copolymer containing 90% by mass or more of the constituent units derived from methacrylic acid monomers and comprising polymer chains A1 and B1. Methacrylic acid monomers include methacrylic acid and methacrylates, which are esters of methacrylic acid. AB block copolymers are polymers with a well-controlled structure and can be manufactured using living polymerization, particularly living radical polymerization. Manufacturing AB block copolymers using living radical polymerization with an organic iodide as the starting compound and an organic compound as the catalyst is preferable because it allows for the use of environmentally friendly materials and offers a high degree of freedom in polymer design. When using living radical polymerization with an organic iodide, the iodine atom, which is the terminal growth group, is preferably bonded to a tertiary carbon atom, so the content of constituent units derived from methacrylic acid monomers in the AB block copolymer is 90% by mass or more. Furthermore, if the content of constituent units derived from methacrylic acid monomers is high, the glass transition temperature of the AB block copolymer increases, thus improving thermal properties such as heat resistance. Furthermore, because methacrylic acid monomers have higher hydrolysis resistance than acrylic acid monomers such as acrylates, they are less prone to hydrolysis even in aqueous liquid media and are relatively stable. Preferably, the AB block copolymer contains 100% by mass of constituent units derived from methacrylic acid monomers.

[0045] The preferred monomers for methacrylic acid are methacrylic acid and methacrylates derived from biomaterials. Alternatively, methacrylates derived from petroleum materials may also be used.

[0046] (Requirement (2)) The polymer chain A1 contains at least 80% by mass of a constituent unit (ii-a) derived from methacrylate derived from biomaterials, and consists of water-insoluble polymer blocks with a number average molecular weight of 1,000 to 10,000 and a molecular weight distribution of less than 1.6. That is, the A1 chain is a polymer block that adsorbs and accumulates on the pigment and can encapsulate the pigment.

[0047] In the A1 chain, the content of the constituent units (ii-a) derived from methacrylates derived from biomaterials is 80% by mass or more, preferably 90% or more. If the content of the constituent units (ii-a) in the A1 chain is less than 80% by mass, there may be insufficient consideration for environmental protection. Furthermore, provided that the content of the constituent units (ii-a) is 80% by mass or more, it may also contain constituent units derived from methacrylates derived from petroleum feedstocks. Furthermore, provided that the A1 chain is a water-insoluble polymer block, it may also contain constituent units derived from methacrylic acid, for example, about 0.5% to 5% by mass.

[0048] The A1 chain consists of polymer blocks with a molecular weight (Mn) of 1,000 to 10,000, preferably 2,000 to 8,000. Due to the relatively large molecular weight of the A1 chain, it readily adsorbs and accumulates on pigments, thus encapsulating them. If the Mn of the A1 chain is less than 1,000, it readily dissolves in liquid media such as water-soluble organic solvents, potentially detaching from the pigment. Conversely, if the Mn of the A1 chain exceeds 10,000, it becomes water-insoluble, making adsorption to pigments difficult.

[0049] The A1 chain has a molecular weight distribution (PDI) of less than 1.6, preferably less than 1.5, and consists of polymer blocks with relatively uniform molecular weight. If the PDI of the A1 chain exceeds 1.6, it contains more polymer blocks outside the aforementioned Mn range, which may make it slightly more difficult to improve pigment dispersibility.

[0050] (Requirement (3)) Polymer chain B1 contains 40-90% by mass of a building block derived from methacrylic acid (ib) and a building block derived from methacrylate derived from biomaterials (ii-b), and has an acid value of 50-260 mg KOH / g, a number average molecular weight of 1,000-10,000, and at least a portion of its carboxyl groups are neutralized by a base. That is, the B1 chain is a water-soluble polymer block that dissolves in water by neutralizing and ionizing at least a portion of its carboxyl groups with a base.

[0051] The B1 chain contains carboxyl groups derived from methacrylic acid and is a polymer block with an acid value of 50-260 mgKOH / g, preferably 60-200 mgKOH / g, and more preferably 70-150 mgKOH / g. Within this acid value range, at least a portion of the carboxyl groups will be neutralized, thus becoming a water-soluble polymer block. If the acid value of the B1 chain is less than 50 mgKOH / g, it may not dissolve in water even after neutralization. On the other hand, if the acid value of the B1 chain exceeds 260 mgKOH / g, it will have excessively high hydrophilicity. Therefore, the water resistance of the recorded image (dried film) may be easily reduced, and the content of constituent units derived from biomaterials methacrylic acid is relatively reduced, resulting in a decrease in environmental responsiveness.

[0052] Even when inks containing AB block copolymers as polymeric dispersants are dried, the B1 chains dissolve in water, allowing them to easily return to a dispersed state by providing an aqueous liquid medium. Furthermore, because water-insoluble A1 chains adsorb and accumulate on the pigment, they do not easily detach from the pigment even after the ink dries, thus restoring a good dispersed state.

[0053] In the B1 chain, the content of the constituent units (ii-b) derived from methacrylate derived from biomaterials is 40-90% by mass. Therefore, AB block copolymers are environmentally friendly polymeric dispersants.

[0054] The B1 chain consists of polymer blocks with a molecular weight (Mn) of 1,000 to 10,000, preferably 2,000 to 8,000, and more preferably 3,000 to 6,000. Furthermore, the "number average molecular weight (Mn) of the B chain" in this specification refers to the "number average molecular weight (Mn) of the entire AB block copolymer minus the number average molecular weight (Mn) of the A chain." If the Mn of the B1 chain is less than 1,000, the water solubility of the B1 chain is slightly insufficient, resulting in inadequate pigment dispersion stability. On the other hand, if the Mn of the B1 chain exceeds 10,000, even if the A1 chain is adsorbed onto the pigment, the entire polymer is still easily detached, and the viscosity of the aqueous pigment dispersion may increase excessively.

[0055] B1 chains are water-soluble polymer blocks that dissolve in water by neutralizing and ionizing at least a portion of their carboxyl groups with a base. The base can be ammonia, organic amines, alkali metal hydroxides, etc. All carboxyl groups may be neutralized by the base, or only a portion of the carboxyl groups may be neutralized within the range where the B1 chain is soluble in water.

[0056] (Requirement (4)) The Mn content of the AB block copolymer is 2,000-20,000, preferably 3,000-15,000, and even more preferably 5,000-12,000. If the Mn content of the AB block copolymer is less than 2,000, it may easily detach from the pigment. On the other hand, if the Mn content of the AB block copolymer exceeds 20,000, the viscosity during polymerization or the viscosity of the aqueous pigment dispersion may increase excessively.

[0057] The molecular weight distribution (PDI) of the AB block copolymer is preferably 1.6 or less, and ideally 1.5 or less. If the PDI of the AB block copolymer exceeds 1.6, it contains more Mn outside the above-mentioned range, which may result in slightly insufficient pigment dispersibility.

[0058] (Manufacturing method of AB block copolymer) The aforementioned AB block copolymer system, used as a polymeric dispersant, can be manufactured according to conventional methods. For example, it can be manufactured using living anionic polymerization, living cationic polymerization, or living radical polymerization. Among these methods, from the viewpoints of conditions, materials, and apparatus, it is preferable to manufacture it using living radical polymerization.

[0059] Living radical polymerization systems include: Atom Transfer Radical Polymerization (ATRP), Nitrogen oxide radical polymerization (NMP), Reversible Addition Fracture Chain Transfer Polymerization (RAFT), Organotelluric Living Radical Polymerization (TERP), Reversible Transfer Catalyst Polymerization (RTCP), and Reversible Catalyst-Mortared Polymerization (RCMP). Among these, RTCP and RCMP, which use organic iodides as starting compounds and organic compounds as catalysts, are more cost-effective and easier to purify and process, as they do not require heavy metals or special compounds.

[0060] In the cases of the RTCP and RCMP methods, since the iodine atoms, which are terminal growth groups, are bonded to tertiary carbon atoms, they easily generate stabilized free radicals. Therefore, AB block copolymers with specific block structures can be easily and precisely manufactured using general equipment, making them preferable. Thus, the content of constituent units derived from methacrylic acid monomers in the AB block copolymer is preferably 90% by mass or higher.

[0061] AB block copolymers can also be manufactured using any polymerization method, including solvent-free polymerization, solution polymerization, and emulsion polymerization. Preferably, solution polymerization is carried out in an organic solvent, and more preferably in an organic solvent identical to the water-soluble organic solvent used in the aqueous pigment dispersion. This allows the AB block copolymer to be used directly in the aqueous pigment dispersion without needing to be removed. The aforementioned RTCP and RCMP methods can be implemented in the aqueous organic solvent used in the aqueous pigment dispersion.

[0062] Either polymer block from the A1 chain or the B1 chain can be polymerized first. Preferably, the B1 chain polymerizes after the A1 chain. If the B1 chain polymerizes first, and the polymerization rate is less than 100%, building blocks from residual monomers may be introduced into the subsequently polymerized A1 chain. In this case, because more methacrylic acid, a component of the B1 chain, may be introduced into the A1 chain, there is a possibility that the A1 chain will be more easily soluble in water.

[0063] (Aqueous pigment dispersion) The aqueous pigment dispersion of the present invention is suitable as a pigment dispersion for use in aqueous inkjet inks. The pigment content in the aqueous pigment dispersion is preferably 5-60% by mass. When the pigment is an organic pigment, the organic pigment content in the aqueous pigment dispersion is preferably 5-30% by mass, more preferably 10-25% by mass. Furthermore, when the pigment is an inorganic pigment, since inorganic pigments have a higher specific gravity, the inorganic pigment content in the aqueous pigment dispersion is preferably 20-60% by mass, more preferably 30-50% by mass.

[0064] The water content in an aqueous pigment dispersion is preferably 20-80% by mass. By forming an aqueous pigment dispersion containing an appropriate amount of water, an aqueous inkjet ink can be prepared.

[0065] The content of water-soluble organic solvent in the aqueous pigment dispersion is preferably below 30% by mass, and more preferably 0.5% to 20% by mass. If the content of water-soluble organic solvent exceeds 30% by mass, the recorded image will not dry easily.

[0066] The preferred content of polymeric dispersant in aqueous pigment dispersions is 0.5% to 20% by mass. If the polymeric dispersant content is less than 0.5% by mass, it will be slightly difficult to disperse the pigment stably. On the other hand, if the polymeric dispersant content exceeds 20% by mass, the viscosity will be too high and will exhibit non-Newtonian viscosity, making it slightly difficult to eject the pigment in a straight line using inkjet technology.

[0067] The content of polymeric dispersant in the aqueous pigment dispersion is preferably determined in accordance with the type, surface properties, and particle size of the pigment. Specifically, relative to 100 parts by weight of organic pigment, the polymeric dispersant is preferably set at 5-50 parts by weight, more preferably 10-30 parts by weight. Furthermore, relative to 100 parts by weight of inorganic pigment, the polymeric dispersant is preferably set at 1-20 parts by weight, more preferably 3-10 parts by weight.

[0068] (Other ingredients) In aqueous pigment dispersions, alkali may be further contained to neutralize polymeric dispersants or for pH adjustment. The aforementioned alkalis may be used. The alkali content in the aqueous pigment dispersion is preferably set at 0.5–5% by mass.

[0069] Aqueous pigment dispersions may also contain surfactants. By including surfactants, the surface tension of the ink can be maintained at a predetermined value. Examples of surfactants include polysiloxane-based, acetylene glycol-based, fluorine-based, epoxy alkane-based, and hydrocarbon-based surfactants. Surfactants derived from natural or biological materials are preferred. From an environmental perspective, surfactants using fatty acids such as palm oil and coconut oil, or aliphatic alcohols, such as polyalkylene glycol esters and ether-based surfactants are preferred. Generally, surfactants can cause ink foaming or cause ink to bounce on film surfaces. Furthermore, since adding surfactants can lead to pigment aggregation, it is best to appropriately control the amount of surfactant added.

[0070] Preservatives may be present in aqueous pigment dispersions. Examples of preservatives include sodium benzoate, benzimidazole, 4-(2-benzimidazole)thiazole, potassium sorbate, sodium sorbate, sodium dehydroacetate, thiazolesulfonamide, and pyridine mercaptan oxides. The preservative content in the ink is based on the total ink volume, preferably set at 0.05~2.0% by mass, more preferably 0.1~1.0% by mass.

[0071] The aqueous pigment dispersion may also contain additives other than the aforementioned water-soluble organic solvents, such as leveling agents, surface tension modifiers, pH adjusters, ultraviolet absorbers, light stabilizers, antioxidants, dyes, fillers, waxes, thickeners, defoamers, mildew inhibitors, antistatic agents, metal microparticles, and magnetic powders, as needed.

[0072] (Physical properties of water-based pigment dispersions) The viscosity of the aqueous pigment dispersion can be appropriately set according to the properties of the pigment and the viscosity of the aqueous inkjet ink to be prepared. When using organic pigments, the optimal viscosity of the aqueous pigment dispersion at 25°C is 3~20 mPa·s. When using inorganic pigments, the optimal viscosity of the aqueous pigment dispersion at 25°C is 5~30 mPa·s.

[0073] The surface tension of aqueous pigment dispersions at 25°C is preferably 15~45 mN / m, and more preferably 20~40 mN / m. The surface tension of aqueous pigment dispersions can be adjusted, for example, by using the type and amount of water-soluble organic solvents, or by adding surfactants.

[0074] (Preparation method of water-based pigment dispersion) Aqueous pigment dispersions can be prepared using conventional methods. For example, water and, if desired, a water-soluble organic solvent are added to prepare a mixture of pigment and polymeric dispersant. Then, the pigment is micro-dispersed using a paint disperser, ball mill, grinder, sand mill, horizontal grinding media disperser, colloid mill, roller mill, etc., to prepare the dispersion. Water and a water-soluble organic solvent are added to the prepared dispersion, and, if necessary, binder components (emulsions), other additives, etc., are added to adjust the concentration to the desired level. Additionally, alkalis can be added to adjust the pH. Furthermore, by adding various additives such as surfactants or preservatives as needed, the desired aqueous pigment dispersion can be obtained. Preferably, after mixing and dispersing the components, a centrifuge or filter is used to remove coarse particles.

[0075] To achieve the desired quantity-average particle size (particle size distribution) of the pigment, methods such as: reducing the size of the grinding media used; increasing the filling rate of the grinding media; extending the processing time; slowing down the discharge rate; and classifying the pigment after grinding using a filter or centrifuge, etc., are preferred. Furthermore, it is preferable to use pigments that have been pre-refined using conventional methods such as salt grinding.

[0076] Water-based inkjet inks The aqueous inkjet ink of the present invention contains the aforementioned aqueous pigment dispersion. In addition to using the aforementioned aqueous pigment dispersion, the ink of the present invention can be prepared according to conventional methods.

[0077] Ink is typically a liquid medium containing water and water-soluble organic solvents. The preferred content of water-soluble organic solvents in ink is 5-30% by mass. Furthermore, ink may contain various additives commonly used in water-based inkjet inks. Examples of additives include: surfactants, organic solvents, humectants, pigment derivatives, dyes, leveling agents, defoamers, UV absorbers, emulsion binders, preservatives, antibacterial agents, waxes, etc. Surfactants may include, for example, ether-based nonionic surfactants such as polyethylene glycol alkyl ethers and acetylene-based surfactants; polysiloxane-based surfactants; fluorinated surfactants, etc. The preferred content of surfactants in ink is 0.1-2% by mass.

[0078] The pigment content in the ink is preferably 1-5% by mass for organic pigments and 1-10% by mass for inorganic pigments. The polymeric dispersant content in the ink is preferably 0.1-5% by mass.

[0079] The ink system, along with the type of pigment, is adjusted to a suitable viscosity to be ejected from the nozzles of the recording head using an inkjet printing method. For example, the optimal ink viscosity when using organic pigments is 2–10 mPa·s. The optimal ink viscosity when using inorganic pigments is 5–30 mPa·s.

[0080] The ideal pH range for ink is 7.0–10.0, with 7.5–9.5 being even better. If the pH of the ink is below 7.0, dispersants may easily precipitate, and pigments may easily aggregate. On the other hand, if the pH of the ink exceeds 10.0, its increased alkalinity will make it more difficult to handle.

[0081] The surface tension of the ink is set appropriately in conjunction with the performance of the inkjet printer. For example, the optimal surface tension of the ink is 15~45 mN / m, and even better is 20~40 mN / m.

[0082] (Adhesive components) The aforementioned inks are effectively used for printing images on various types of paper, such as plain paper, photo paper, glossy photo paper, and coated paper. However, when printing images on plastic films, molded plastic products, fibers, fabrics, metals, ceramics, etc., it is preferable that the ink further contains a binder component, which is a film-forming agent. By using ink containing a binder component for printing, the binder component forms a film, which can improve the adhesion, dry rubbing resistance, wet rubbing resistance, anti-sticking properties, chemical resistance, solvent resistance, and scratch resistance of the obtained image (dry film). Furthermore, the binder component content in the ink is preferably set at 1 to 10% by mass.

[0083] The adhesive components can be made from a variety of polymers. Examples of polymers include: acrylic polymers, styrene-acrylic polymers, amine polymers, polyester polymers, and polyolefin polymers. These polymers can be used in the form of aqueous solutions, aqueous dispersions, and emulsions.

[0084] Acrylic polymers and styrene-acrylic polymers can be used as emulsions with a dispersed particle size (number average particle size) of 50-200 nm obtained by polymerization of acrylic monomers such as styrene or methacrylates in the presence of surfactants. These polymers are preferably AB block copolymers or ABA block copolymers having water-insoluble A chains and water-soluble B chains.

[0085] The amine ester polymer system can be obtained by reacting diisocyanates, polyols, short-chain diols, and diol monocarboxylic acids, and, if necessary, by reacting hydrazine or isophorone diamine to extend the chain, followed by self-emulsification with alkaline water to obtain an aqueous dispersion with a number average particle size of 50-200 nm. The diisocyanate, besides isophorone diisocyanate and hexamethylene diisocyanate, is preferably derived from natural materials such as lysine diisocyanate and pentamethylene diisocyanate. The polyol, besides polycarbonate diol, is preferably derived from natural materials such as castor oil polyol. The short-chain diol, besides diethylene glycol, is preferably derived from natural materials such as ethylene glycol, 1,3-propanediol, and isosorbide. The diol monocarboxylic acid is preferably dimethylolpropionic acid.

[0086] Polyester polymer systems can be obtained by dehydrogenating or dealcoholizing dicarboxylic acids such as adipic acid and phthalic acid with diols such as ethylene glycol, propylene glycol, neopentyl glycol, and cyclohexanediol, as well as monomers with sulfonic acid groups such as sodium dimethylisophthalate sulfonate to form polyesters, and then adding water while forcibly stirring.

[0087] Polyolefin polymer systems can be obtained by dissolving acrylic copolymers of polyethylene or polypropylene, or maleic acid grafts, in an organic solvent, then adding an alkaline aqueous solution while forcibly stirring to form an aqueous dispersion, and further performing organic solvent removal treatment to obtain an aqueous dispersion.

[0088] The adhesive composition is preferably a polymer that meets the following requirements (5) to (9).

[0089] [Requirements (5)]: An AB block copolymer containing polymer chains A2 and B2, comprising more than 90% by mass of constituent units derived from methacrylic acid monomers. [Requirement (6)]: The above polymer chain A2 system It contains more than 80% by mass of constituent units derived from bio-methacrylates derived from biological materials, and is... The number of molecules with an average molecular weight of 10,000 to 30,000 Water-insoluble polymer blocks with a molecular weight distribution of less than 1.6. [Requirement (7)]: The above polymer chain B2 system Contains building blocks derived from methacrylic acid, and Contains 40-90% by mass of constituent units derived from bio-methacrylates derived from biological materials, and is Acid value of 50~150mgKOH / g The number of molecules with an average molecular weight of 5,000 to 20,000 A polymer block in which at least a portion of the carboxyl group is neutralized by a base. [Requirements (8)]: The number average molecular weight is 15,000 to 50,000, and the molecular weight distribution is below 1.6. [Requirements (9)]: The number of particles with an average diameter of 10~200nm.

[0090] The polymer system that meets the above requirements (5) to (9) has a structure similar to the aforementioned AB block copolymers used as polymeric dispersants. That is, since it is an AB block copolymer obtained using monomers derived from biological materials, it is environmentally friendly, and by using this polymer as an adhesive component, an image (dry film) with excellent adhesion, abrasion resistance and anti-sticking properties can be formed.

[0091] [Requirement (5)] The adhesive component is an AB block copolymer containing 90% or more of the constituent units derived from methacrylic acid monomers and comprising polymer chains A2 and B2. The methacrylic acid monomers are methacrylic acid and methacrylates, which are esters of methacrylic acid. The AB block copolymer is a polymer with a precisely controlled structure, which can be manufactured using living polymerization, particularly living radical polymerization. Using living radical polymerization with an organic iodide as the starting compound and an organic compound as the catalyst to manufacture AB block copolymers is preferable because it allows for the use of environmentally friendly materials and offers a high degree of freedom in polymer design. When using living radical polymerization with an organic iodide, it is preferable that the iodine atom, which is the terminal growth group, is bonded to a tertiary carbon atom, so that the constituent units derived from methacrylic acid monomers in the AB block copolymer contain 90% or more of the constituent units. Furthermore, if the content of constituent units derived from methacrylic acid monomers is high, the glass transition temperature of the AB block copolymer increases, thus improving thermal properties such as heat resistance. Furthermore, since methacrylic acid monomers have higher hydrolysis resistance than acrylic acid monomers such as acrylates, they are not easily hydrolyzed even in aqueous liquid media and are relatively stable. Preferably, the AB block copolymer contains 100% by mass of constituent units derived from methacrylic acid monomers.

[0092] The preferred monomers for methacrylic acid are methacrylic acid and methacrylates derived from biomaterials. Alternatively, methacrylates derived from petroleum materials may also be used.

[0093] [Requirement (6)] The polymer chain A2 contains at least 80% by mass of bio-methacrylate-derived constituent units derived from biological materials, and these are water-insoluble polymer blocks with a number average molecular weight of 10,000 to 30,000 and a molecular weight distribution of 1.6 or less. This A2 chain provides adhesion and abrasion resistance to the printing substrate. The A2 chain contains at least 80% by mass of bio-methacrylate-derived constituent units, preferably at least 90%. If the content of these constituent units in the A2 chain is less than 80% by mass, environmental considerations may be insufficient. Furthermore, provided the content of these constituent units is at least 80% by mass, it may also contain constituent units derived from petroleum-based methacrylates. Additionally, provided the A2 chain is a water-insoluble polymer block, it may also contain, for example, approximately 0.5% to 5% by mass of methacrylate-derived constituent units.

[0094] The A2 chain consists of polymer blocks with a molecular weight (Mn) of 10,000 to 30,000, preferably 11,000 to 25,000. Due to the sufficiently large molecular weight of the A2 chain, it exhibits excellent adhesion to the printing substrate and can form images (dried films) with excellent abrasion resistance. If the Mn of the A2 chain is less than 10,000, the adhesion of the image may be slightly reduced. On the other hand, if the Mn of the A2 chain exceeds 30,000, there is a tendency for a decrease in polymerization rate and a broadening of the molecular weight distribution.

[0095] The A2 chain has a relatively uniform molecular weight distribution (PDI) of less than 1.6, preferably less than 1.5, and more preferably less than 1.4. If the PDI of the A2 chain exceeds 1.6, the content of polymer blocks outside the above-mentioned Mn range will increase.

[0096] [Requirement (7)] Polymer chain B2 contains constituent units derived from methacrylic acid, and 40-90% by mass of constituent units derived from methacrylates derived from biological materials. It is a polymer block with an acid value of 50-150 mg KOH / g, a number average molecular weight of 5,000-20,000, and at least a portion of its carboxyl groups neutralized by a base. In other words, the B2 chain is a water-soluble polymer block that dissolves in water through the neutralization and ionization of at least a portion of its carboxyl groups by a base.

[0097] The B2 chain contains a carboxyl group derived from methacrylic acid and is a polymer block with an acid value of 50-150 mgKOH / g, preferably 60-130 mgKOH / g. If the acid value of the B2 chain is less than 50 mgKOH / g, the B2 chain is not easily dissolved in water, which may compromise particle stability. Furthermore, it may result in insufficient redissolution of the ink. On the other hand, if the acid value of the B2 chain exceeds 150 mgKOH / g, the ink viscosity may be too high, and the water resistance of the image may be slightly insufficient.

[0098] In the B2 chain, the content of constituent units derived from methacrylate derived from biomaterials is 40-90% by mass, preferably 50-90% by mass, and even more preferably 60-85% by mass. Therefore, AB block copolymers are environmentally friendly adhesive components.

[0099] The B2 chain consists of polymer blocks with a molecular weight (Mn) of 5,000 to 20,000, preferably 6,000 to 10,000. By sufficiently stabilizing and particle-forming the adhesive in water and increasing the molecular weight of the B chain, it can work in conjunction with the A chain to exert the film-forming effect of the adhesive components, thus contributing to improved durability of printed materials. If the Mn of the B2 chain is less than 5,000, there may be slightly insufficient particle stability in aqueous liquid media. On the other hand, if the Mn of the B2 chain exceeds 20,000, there may be excessive increase in ink viscosity or a slight decrease in the water resistance of the image.

[0100] The B2 chain is a water-soluble polymer block that dissolves in water by neutralizing and ionizing at least a portion of its carboxyl groups with a base. The base can be ammonia, organic amines, alkali metal hydroxides, etc. All carboxyl groups can be neutralized by the base, or only a portion of the carboxyl groups can be neutralized within the range where the B2 chain is soluble in water. Specifically, from the viewpoint of pH stability, it is preferable that at least 90 mol% of the carboxyl groups are neutralized.

[0101] [Requirement (8)] The Mn content of the AB block copolymer is 15,000 to 50,000, preferably 16,000 to 30,000. If the Mn content of the AB block copolymer is less than 15,000, the resulting image (dried film) will have slightly poorer durability. On the other hand, if the Mn content of the AB block copolymer exceeds 50,000, the ink viscosity will increase excessively, or the ink will contain more polymers outside the aforementioned molecular weight range.

[0102] The molecular weight distribution (PDI) of the AB block copolymer is preferably 1.6 or less, and more preferably 1.5 or less. If the PDI of the AB block copolymer exceeds 1.6, it tends to contain more molecules outside the aforementioned Mn range.

[0103] [Requirement (9)] The AB block copolymer has particles (binder particles) with a number average particle size of 10-200 nm, preferably 50-150 nm. The "number average particle size of polymer particles" in this specification is a value measured using dynamic light scattering. When the AB block copolymer is mixed with water, the A2 chains form particles, and the B2 chains dissolve in the water to form binder particles, thus forming micelles, aqueous dispersions, or emulsions. If dissolved without particle formation, the ink viscosity may increase excessively. In contrast, because the AB block copolymer forms particles, the ink viscosity does not increase excessively. If the number average particle size of the binder particles formed by the AB block copolymer is less than 10 nm, the ink viscosity tends to increase because it is almost equal to that in the dissolved state. On the other hand, if the number average particle size of the binder particles exceeds 200 nm, the ejection performance from the inkjet printhead nozzle may decrease slightly.

[0104] Bio-derived methacrylates are preferably used, including: ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate. The adhesive components can be, for example, ABC triblock structures, ABCB tetrablock structures, and gradient structures. In the case of ABC triblock structures, any A-(BC) block structure where the A chain is insoluble, the B chain is water-soluble, and the C chain is water-soluble is acceptable. Alternatively, an ABA block structure is also acceptable.

[0105] The aforementioned AB block copolymers used as adhesive components can be manufactured using conventional methods. For example, they can be manufactured using living anionic polymerization, living cationic polymerization, or living radical polymerization. From the viewpoints of conditions, materials, and equipment, manufacturing using living radical polymerization is preferred. In particular, the RTCP or RCMP methods, which use organic iodides as starting compounds and organic compounds as catalysts, are more cost-effective and easier to refine and process, as they do not require heavy metals or special compounds. Furthermore, solution polymerization is preferred, carried out in a water-soluble organic solvent formulated in ink. After solution polymerization, the adhesive component can be formed by adding an alkali.

[0106] <Dry Skin Mask> The aforementioned water-based inkjet ink can be applied to inkjet printers equipped with recording heads such as thermal printheads or piezoelectric printheads, and can record (print) images on various printing substrates using inkjet recording. Specifically, it can record images on printing substrates such as paper, photo paper, glossy photo paper, polyolefin or polyethylene terephthalate plastic films, fibers, fabrics, ceramics, metals, and molded objects. Moreover, the recorded images are a so-called "dry film" with excellent durability, including high color saturation, high color rendering, adhesion, and abrasion resistance. That is, by using the water-based inkjet ink of the present invention, a dry film containing components derived from (meth)acrylates derived from biological materials and being environmentally friendly and a carbon-neutral film-like dry material can be produced. [Example]

[0107] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples without departing from its spirit. Unless otherwise stated, the descriptions of the relevant ingredient amounts in "parts" and "%" are "mass basis".

[0108] <Manufacturing of Polymer Dispersants> (Implementation Example 1) In a reaction vessel equipped with a stirrer, thermometer, reflux pipe, dripping device, and nitrogen inlet pipe, 300 parts of diethylene glycol (BDG) were added while nitrogen was being foamed, and the mixture was heated to 70°C. In another vessel, 30 parts of isocyanate methacrylate (IBXMA), 120 parts of tetrahydrofurfuryl methacrylate (THFMA), 60 parts of lauryl methacrylate (LMA), 60 parts of 2-hydroxyethyl methacrylate (HEMA), 30 parts of methacrylic acid (MAA), and 2 parts of 2,2'-azobis(2,4-dimethylpentanonitrile) (trade name "V-65", manufactured by Fujifilm Corporation, V-65) were added and mixed, and homogenized to obtain a monomer mixture. Isocyanate methacrylate was obtained by isomerizing α-pinene obtained from pine resin or pine oil, followed by reaction with camphene and methacrylic acid to obtain a methacrylate ester (71.4% purity). Tetrahydrofurfuryl methacrylate is an ester of tetrahydrofurfuryl alcohol (obtained by hydrogenation of furfural from corn kernels, etc.) and methacrylic acid (biomass 55.5%). Lauryl methacrylate is an ester of lauryl alcohol (obtained by hydrogen reduction of lauric acid, a fatty acid fraction obtained by hydrolysis of oils such as palm kernel oil or coconut oil) and methacrylic acid (biomass 75.0%). One-third of the prepared monomer mixture was added dropwise to the reaction vessel, and the remaining monomer mixture was added dropwise after 2 hours. Polymerization was carried out at 70°C for 8 hours to synthesize the polymer, obtaining a liquid containing the polymer. A sample of the liquid was taken, and the molecular weight of the polymer was determined using a gel permeation chromatography (GPC) analyzer with tetrahydrofuran as the developing solvent. The results showed that the number average molecular weight (Mn) of the polymer was 19,800, the molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) was 2.01, and the polymerization rate was approximately 100%. The polymerization rate is calculated by measuring a portion of the obtained liquid in an aluminum pan, drying it for 3 hours using a blower dryer at 150°C, and then calculating the remaining amount.

[0109] A portion of the obtained liquid was sampled and homogenized with a 1 / 1 (volume ratio) toluene / ethanol mixture. A few drops of 1% phenolphthalein / ethanol solution were added, and the acid value of the polymer was determined by titration with 0.1 equivalents of potassium hydroxide ethanol solution. The resulting acid value was 64.9 mg KOH / g. The polymer-containing solution was neutralized by adding a mixture of 13.9 parts sodium hydroxide and 136.1 parts water to obtain an aqueous solution of dispersant D-1 (a viscous, pale yellow, transparent liquid). The resulting aqueous solution had a solid content of 42.1% and a pH of 10.1.

[0110] The obtained dispersant D-1 (polymer) contains 70% constituent units derived from methacrylate derived from biomaterials. Furthermore, the biomass of the obtained polymer is calculated using the following formula. Polymer biomass = (moles of each monomer in 100 parts of polymer × carbon number of each monomer × total biomass of each monomer) ÷ (moles of each monomer in 100 parts of polymer × total carbon number of each monomer)

[0111] In the case of dispersant D-1, the biomass can be calculated as (0.045×14×71.4%(IBXMA)+0.235×9×55.5%(THFMA)+0.078×16×75.0%(LMA)+0.154×6×0%(HEMA)+0.116×4×0(MAA))÷(0.045×14(IBXMA)+0.235×9(THFMA)+0.078×16(LMA)+0.154×6(HEMA)+0.116×4(MAA))=2.56÷5.38=47.5%. Since not all residues of the initiator are incorporated into the polymer, they are not used in the biomass calculation.

[0112] 1,000g of the polymer contains 53.9 mol of carbon. The amount of carbon (mol) in 1,000g of the polymer can be calculated from the mass fraction of each monomer constituting the polymer, the molecular weight of the monomer, and the number of carbon atoms. The biomass of the polymer is 47.5%, therefore 1,000g of the polymer contains 25.6 mol of carbon derived from biological materials. Combustion of 1,000g of this polymer will emit 1,126g of carbon dioxide, therefore the carbon dioxide absorption of this polymer is "1,126 (g / 1,000g)". When using 1,000g of this polymer to form a coating (dry film), 1,126g of carbon dioxide will be stored, which helps to reduce carbon dioxide emissions.

[0113] (Perform synthetic examples 2-4, compare synthetic examples 1-3) Except for the materials of the types and amounts (unit: parts) shown in Tables 1 and 2, all other aqueous solutions of dispersants D-2~4 and dispersants R-1~3 were obtained in the same manner as in Synthesis Example 1 described above. The physical properties of the obtained dispersants are shown in Tables 1 and 2. Furthermore, the abbreviations in Tables 1 and 2 have the following meanings: MPG: Propylene Glycol Monomethyl Ether •StMA: Stearyl methacrylate (an ester of stearyl alcohol, obtained by hydrogen reduction of oleic acid, a fatty acid fraction from the hydrolysis of oils such as palm kernel oil or coconut oil, and methacrylic acid (81.8% purity)). • OA: Octyl acrylate (an ester of octanol and acrylic acid obtained by hydrogen reduction of octanoic acid, a fatty acid fraction obtained from the hydrolysis of oils such as palm kernel oil or coconut oil, etc. (72.7% purity)). EMA: Ethyl methacrylate (an esterification of ethanol obtained from the breakdown of starch or sugar with methacrylate (biomass 33.3%)). • Iconic acid: A monomer with a carboxyl group obtained by fermentation of starch and other substances (100% biomass). Styrene (a material derived from petroleum) MMA: Methyl methacrylate (a petroleum-derived material) ·BA: Butyl acrylate (a petroleum-derived material) ·2-EHMA: 2-Ethylhexyl methacrylate (a petroleum-derived material) AIBN: 2,2'-Azobis(4-methoxy-2,4-dimethylpentanonitrile)

[0114] Furthermore, the "environmental friendliness" evaluation criteria in Tables 1 and 2 are as follows. ○: Biomass content is above 40%, and carbon dioxide absorption is above 1,000g / 1,000g. ×: Biomass content is less than 40%, or carbon dioxide absorption is less than 1,000g / 1,000g.

[0115] [Table 1] Implementing a synthetic example 1 2 3 4 dispersant D-1 D-2 D-3 D-4 solvent BDG 300 150 150 150 MPG 150 150 ethanol 150 Monomers derived from biomaterials IBXMA 30 30 30 30 THFMA 120 180 120 180 LMA 60 30 StMA 60 60 OA 30 EMA 60 Iconic acid 30 30 Monomers derived from petroleum materials HEMA 60 MAA 30 30 Initiator V-65 2 2 AIBN 3 3 Neutralizing agent NaOH 13.9 28% ammonia water 21.8 22.4 28 Solid content (%) 42.1 40.8 41.3 41.1 pH 10.1 9.7 8.1 9.8 Mn 19,800 20,200 10,200 8,700 PDI 2.01 2.12 2.13 2.10 Acid value (mgKOH / g) 64.9 65.2 86.2 86.1 Content (%) of constituent units derived from (meth)acrylates derived from biological materials 70 90 90 90 Biomass (%) 47.5 58.8 60.3 66.7 Carbon dioxide absorption (g / 1,000g) 1,126 1,440 1,435 1,609 Environmental protection 〇 〇 〇 〇

[0116] [Table 2] Comparative Synthesis Example 1 2 3 dispersant R-1 R-2 R-3 solvent BDG 150 150 150 MPG 150 150 150 Monomers derived from biomaterials IBXMA 30 THFMA 30 60 StMA 60 Monomers derived from petroleum materials St 60 60 60 MMA 60 60 60 BA 60 2-EHMA 60 HEMA 60 30 30 MAA 60 30 30 Initiator V-65 2 2 AIBN 4 Neutralizing agent NaOH 27.9 28% ammonia water 21.1 21.1 Solid content (%) 41.9 40.8 41.3 pH 10.3 9.7 8.1 Mn 16,900 21,000 8,900 PDI 2.23 2.00 2.34 Acid value (mgKOH / g) 129.4 65.2 65.1 Content (%) of constituent units derived from methacrylates derived from biological materials 0 20 40 Biomass (%) 0 12.8 28.3 Carbon dioxide absorption (g / 1,000g) 0 326 725 Environmental protection × × ×

[0117] (Implementation Example 5) In a reaction vessel equipped with a stirrer, thermometer, reflux pipe, dripping device, and nitrogen inlet pipe, the following components were added: 119.0 parts tripropylene glycol monomethyl ether, 59.5 parts propylene glycol monopropyl ether, 1.0 part iodine, 3.6 parts 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile) (trade name "V-70", manufactured by Fujifilm Corporation, V-70), 57.1 parts THFMA, 24.0 parts IBXMA, 16.4 parts EMA, 21.5 parts MAA, and 0.02 parts N-iodosuccinimide (NIS). The mixture was heated to 42°C while nitrogen was flowing through it and polymerized for 8 hours to form a polymer. A sample was taken, and the polymerization rate was approximately 100%. The resulting polymer had a Mn content of 8,900, a PDI content of 1.49, and an acid value of 117.7 mg KOH / g.

[0118] Neutralization was achieved by adding a mixture of 10 parts sodium hydroxide and 109 parts water to obtain an aqueous solution of dispersion D-5 (a pale yellow, transparent, low-viscosity liquid). The solid content of the obtained aqueous solution was 25.3%, and the pH was 10.2. This polymer is formed by living radical polymerization (reversible transfer catalyst polymerization, RTCP method) using iodine as the initiating group and an organic compound that generates free radicals after iodine removal as the catalyst, resulting in a relatively uniform molecular weight. In the obtained dispersant D-5 (polymer), the content of constituent units derived from methacrylate derived from biomaterials was 81.9%. Furthermore, the biomass of dispersant D-5 (polymer) was 45.6%, and the carbon dioxide absorption was 1,124 g / 1,000 g.

[0119] (Implementation Example 6) In a reaction vessel equipped with a stirrer, thermometer, reflux pipe, dripping device, and nitrogen inlet pipe, the following components were added: 283.1 parts BDG, 119.2 parts THFMA, 2.0 parts iodine, 3.6 parts V-70, and 0.1 parts NIS. The mixture was heated to 45°C while undergoing nitrogen foaming and polymerization for 4 hours to form the A-chain (polymer). A sample was taken, and the measured Mn content was 5,100, PDI was 1.21, and the polymerization rate was approximately 100%. A mixture of 119 parts THFMA and 30.2 parts MAA was added, and polymerization was carried out at 45°C for 4 hours to form the B-chain, yielding an AB block copolymer. The AB block copolymer had an Mn content of 10,700, a PDI of 1.31, an acid value of 73.0 mg KOH / g, and a polymerization rate of approximately 100%. Furthermore, the Mn content of the B chain (total Mn - Mn content of the A chain) is 5,600, and the acid value calculated from the adjustment value considering the polymerization rate is 132 mg KOH / g. After cooling the polymerization solution to room temperature, a mixture of 23.4 parts of 28% ammonia and 118.5 parts of water was added for neutralization to obtain an aqueous solution of dispersant D-6 (a light brown transparent liquid). The solid content of the obtained aqueous solution is 41.1%, and the pH is 9.2. The content of constituent units derived from methacrylate derived from biomaterials in the obtained dispersant D-6 (polymer) is 88.7%. Furthermore, the biomass of dispersant D-6 (polymer) is 49.9%, and the carbon dioxide absorption is 1,145 g / 1,000 g.

[0120] (Synthesis Examples 7-13) Except for the various materials of the types and amounts (unit: parts) shown in Table 3, all other aqueous solutions of dispersants D-7 to 13 were obtained in the same manner as in Synthesis Example 6 described above. The physical properties of the obtained dispersants are shown in Table 3. Also, "DMEA" in Table 3 refers to dimethylamine ethanol.

[0121] [Table 3] Implementing a synthetic example 6 7 8 9 10 11 12 13 dispersant D-6 D-7 D-8 D-9 D-10 D-11 D-12 D-13 solvent BDG 238.1 162.9 150 152.6 164.5 168 170 156 MPG 162.9 150 152.6 164.5 168 170 156 iodine 1 3 2 2 3 3 3 4 V-70 3.6 9 6 6 9 9 9 12 NIS 0.02 0.05 0.03 0.03 0.02 0.02 0.02 0.05 Chain A IBXMA 22.2 22.2 THFMA 119 168.3 136 136 142.8 127.5 75.6 68 StMA 30.3 50.7 50.7 40.6 Mn 5,100 4,700 6,100 5,900 5,800 6,200 5,200 3,300 PDI 1.21 1.26 1.34 1.34 1.23 1.38 1.27 1.19 B-Chain THFMA 119.2 119 102 85 123.2 112.2 175 149.6 IBXMA 22.2 MAA 30.2 19 25.8 25.8 14.8 25.8 16.2 34.4 Mn 5,600 3,900 4,700 4,600 3,900 4,000 5,500 4,700 Acid value (mgKOH / g) 132 89.9 130.9 126.5 69.6 122 55.1 122 All Mn 10,700 8,600 10,800 10,500 9,700 10,200 10,700 8,100 PDI 1.31 1.33 1.41 1.41 1.34 1.36 1.39 1.24 Acid value (mgKOH / g) 73 40.5 58.8 58 31 53.5 33.1 76.3 Neutralizing agent 28% ammonia solution 23.4 13.4 18.2 10.5 18.2 11.5 24.3 DMEA 31.5 Solid content (%) 41.1 41.1 40.9 40.8 41.6 40.9 40.9 40.9 pH 9.2 9.9 9.8 9.8 9.6 9.8 9.6 9.5 Content (%) of constituent units derived from methacrylates derived from biological materials 88.7 91.6 91 91.1 91.7 91.8 87.8 88.3 Biomass (%) 49.9 51.3 52.5 54 54.6 56.6 54.7 54.3 Carbon dioxide absorption (g / 1,000g) 1,145 1,182 1,226 1,280 1,285 1,352 1,301 1,285 Environmental protection 〇 〇 〇 〇 〇 〇 〇 〇

[0122] <Preparation of Pigment Dispersion> (Example 1) A transparent liquid was obtained by mixing 89.1 parts of an aqueous solution of dispersant D-1 with 337.8 parts of deionized water. 150 parts of copper phthalocyanine pigment PB-15:3 (trade name "Indigo A220JC", manufactured by Daihatsu Seika Co., Ltd.) were added to the obtained solution, and the mixture was stirred for 30 minutes using a disperser to prepare the grinding matrix. Dispersion was performed using a horizontal media disperser (trade name "0.6L ECM type bead mill", manufactured by SHINMARU ENTERPRISES, with zirconia beads of 0.5 mm diameter) at a circumferential speed of 10 m / s to ensure thorough dispersion of the pigment in the grinding matrix. 256.4 parts of water were added to adjust the pigment concentration to 18%. The grinding matrix was centrifuged (7,500 rpm, 20 minutes) and then filtered using a 5 μm pore size membrane filter. After dilution with water, an inkjet pigment dispersion-1 (indigo blue) with a pigment concentration of 14% was obtained.

[0123] The number-average particle size of the pigment in pigment dispersion-1, measured using a particle size analyzer (trade name "NICOMP 380ZLS-S", manufactured by International Business), was 138.5 nm, confirming that the pigment was micro-dispersed. Furthermore, the viscosity of pigment dispersion-1 was 3.70 mPa·s, and the pH was 9.4. The viscosity of pigment dispersion-1 was measured at 25°C using an E-type viscometer at 60 revolutions per minute. After storage at 70°C for one week, the number-average particle size of the pigment in pigment dispersion-1 was 138.5 nm, and the viscosity was 3.66 mPa·s. This confirms that pigment dispersion-1 has excellent storage stability.

[0124] (Examples 2-13, Comparative Examples 1-3) Except for the dispersants shown in Table 4, pigment dispersions -2 to -13 and pigment dispersions -1H to -3H were prepared in the same manner as in Example 1 above. The characteristics of each pigment dispersion (average particle size and viscosity of pigment immediately after dispersion and after storage at 70°C for 1 week) are shown in Table 4.

[0125] Furthermore, the "Evaluation" benchmark system in Table 4 is as follows. ○: The pigment is micro-dispersed, and even after being stored at 70°C for one week, the average particle size and viscosity of the pigment do not change significantly. △: Although the pigment is slightly dispersed, its viscosity is higher than 4 mPa·s. Furthermore, even after being stored at 70°C for one week, the average particle size and viscosity of the pigment remain almost unchanged. ×: Although the pigment is slightly dispersed, if it is stored at 70°C for 1 week, the average particle size or viscosity of the pigment will increase.

[0126] [Table 4] Pigment dispersion dispersant Immediately after dispersing Store at 70℃ for 1 week evaluate Number average particle size (nm) Viscosity (mPa·s) Number average particle size (nm) Viscosity (mPa·s) Example 1 -1 D-1 138.5 3.70 138.5 3.66 〇 Example 2 -2 D-2 134.0 3.29 134.0 3.19 〇 Example 3 -3 D-3 140.1 3.85 140.9 3.76 〇 Example 4 -4 D-4 139.4 3.38 139.4 3.33 〇 Example 5 -5 D-5 127.1 3.24 121.6 3.21 〇 Example 6 -6 D-6 120.3 3.90 120.3 3.73 〇 Example 7 -7 D-7 112.0 3.54 108.3 3.46 〇 Example 8 -8 D-8 110.0 3.65 111.0 3.65 〇 Example 9 -9 D-9 108.3 3.28 108.6 3.16 〇 Example 10 -10 D-10 116.4 3.37 117.9 3.28 〇 Example 11 -11 D-11 118.6 3.46 119.6 3.33 〇 Example 12 -12 D-12 105.3 3.28 103.5 3.16 〇 Example 13 -13 D-13 104.3 3.56 105.2 3.54 〇 Comparative Example 1 -1H R-1 139.6 3.65 189.6 3.56 × Comparative Example 2 -2H R-2 149.3 4.06 156.3 4.23 × Comparative Example 3 -3H R-3 149.6 4.23 150.3 4.33 △

[0127] (Examples 14-16) Except for replacing the copper phthalocyanine pigment PB-15:3 with azo yellow pigment PY-155 (trade name "VERSAL YELLOW 4GNY", manufactured by Clariant Japan), quinacrine pigment PR-122 (trade name "CFR130P", manufactured by Dainippon Seika Co., Ltd.), and carbon black pigment PB-7 (trade name "S170", manufactured by Degussa), the pigment dispersions -14 to 16 were obtained in the same manner as in Example 10 above. The characteristics of each pigment dispersion (average particle size and viscosity of the pigment immediately after dispersion and after storage at 70°C for 1 week) are shown in Table 5.

[0128] [Table 5] Pigment dispersion dispersant Immediately after dispersing Store at 70℃ for 1 week Number average particle size (nm) viscosity (mPa·s) Number average particle size (nm) viscosity (mPa·s) Example 14 -14 D-10 151.8 4.04 150.9 4.01 Example 15 -15 D-10 125.0 3.09 125.0 2.99 Example 16 -16 D-10 109.1 3.00 111.0 3.13

[0129] (Example 17) 401.2 parts of water and 98.8 parts of an aqueous solution of dispersant D-5 were mixed and homogenized to obtain a liquid. 500 parts of CI Pigment White 6 (trade name "JR-404", manufactured by Ishihara Sangyo Co., Ltd.) were added to the obtained liquid. The mixture was thoroughly stirred using a high-speed stirrer to obtain a mixture containing pigment and dispersant. The pigment was fully dispersed in the mixture using a horizontal media disperser, and then filtered using a 10 μm pore size membrane filter to remove coarse particles, obtaining a 50% pigment concentration inkjet pigment dispersion-17 (white). The number-average particle size of the pigment in pigment dispersion-17 was 263.7 nm, and the viscosity was 12.6 mPa·s. After storage at 70°C for one week, the number-average particle size of the pigment in pigment dispersion-17 was 226.4 nm, and the viscosity was 12.8 mPa·s.

[0130] <Ink (1) Preparation> (Examples 18-27, Comparative Examples 4-6) 28.7 parts of the pigment dispersion shown in Table 6, 1.5 parts of BDG, 5 parts of 2-pyrrolidone, 20.0 parts of glycerol, 1 part of surfactant (trade name "SURFYNOL 465", manufactured by Air Products), and 44.8 parts of water were mixed and thoroughly stirred. The mixture was then filtered using a membrane filter with a pore size of 10 μm to prepare inkjet ink. The characteristics of each ink (average particle size and viscosity of pigment immediately after preparation and after storage at 70°C for one week) are shown in Table 6. Furthermore, the "Evaluation" criteria in Table 6 are as follows. ○: Even after being stored at 70°C for one week, the average particle size and viscosity of the pigment did not change significantly. △: Even after being stored at 70°C for 1 week, the average particle size of the pigment does not change significantly, but the viscosity increases. ×: Although the pigment is slightly dispersed, if it is stored at 70°C for 1 week, the average particle size or viscosity of the pigment will increase.

[0131] [Table 6] Pigment dispersion Immediately after modulation Store at 70℃ for 1 week evaluate Number average particle size (nm) viscosity (mPa·s) Number average particle size (nm) viscosity (mPa·s) Example 18 -1 138.5 3.55 140.4 3.89 △ Example 19 -4 139.4 3.39 142.2 3.99 △ Example 20 -5 127.0 3.40 126.3 3.39 〇 Example 21 -7 112.0 3.38 111.0 3.38 〇 Example 22 -8 110.0 3.40 110.0 3.41 〇 Example 23 -10 118.6 3.49 118.6 3.40 〇 Example 24 -13 104.3 3.57 104.3 3.56 〇 Example 25 -14 151.8 3.56 151.3 3.55 〇 Example 26 -15 125.0 3.40 125.3 3.41 〇 Example 27 -16 109.1 3.46 109.3 3.46 〇 Comparative Example 4 -1H 139.5 3.61 175.6 4.32 × Comparative Example 5 -2H 149.3 3.60 155.0 4.63 × Comparative Example 6 -3H 149.6 3.56 150.3 4.51 ×

[0132] <Evaluation of Ink (1)> (Implementation Examples 1-4) The inks obtained in Examples 23 and 25-27 were filled into ink cartridges and installed in an inkjet printer (trade name "EM930C", manufactured by Seiko Epson Corporation). Printed images were obtained by printing physical images on (i) glossy photo paper (PGPP) and (ii) plain paper (trade name "4024", manufactured by Xerox Corporation) in the "photo 720dpi" printing mode. It was confirmed that any ink could be ejected from the inkjet nozzles without any problems.

[0133] Using an optical density meter (trade name "Macbeth RD-914", manufactured by Macbeth Corporation), the chroma (C*), optical density (OD value), and 20° gloss of images recorded on PGPP were measured, as well as the optical density (OD value) of images recorded on ordinary paper. The results are shown in Table 7. Furthermore, each characteristic value was measured five times and the average value was used. Additionally, the abrasion resistance of the images recorded on PGPP was evaluated by rubbing the surface with a finger. The results are shown in Table 7.

[0134] [Table 7] Implementation Examples ink Abrasion resistance PGPP Ordinary paper C * OD value 20° gloss OD value 1 Example 23 〇 64.6 2.22 25.6 1.16 2 Example 25 〇 115.2 1.59 34.9 1.18 3 Example 26 〇 84.3 2.11 31.5 1.99 4 Example 27 〇 - 2.21 46.3 1.19

[0135] The same tests as described above were also performed on the inks obtained in other embodiments, confirming that they could be dispensed from the nozzle without any problems and could record images with high color rendering and abrasion resistance.

[0136] <Preparation of Adhesive Components> (Implementation Example 14) In a reaction vessel equipped with a stirrer, thermometer, reflux pipe, dripping device, and nitrogen inlet pipe, the following components were added: BDG: 360.2 parts, THFMA: 124.3 parts, IBXMA: 50.5 parts, iodine: 1.5 parts, V-70: 5.5 parts, and NIS: 0.3 parts. The mixture was heated to 45°C while simultaneously foaming with nitrogen and polymerized for 4 hours to form A-chains (polymer). A sample was taken, and the measured Mn content was 10,200, PDI content was 1.29, and the polymerization rate was approximately 100%. A mixture of THFMA: 86.8 parts and MAA: 22.6 parts was added, and polymerization was carried out at 45°C for 4 hours to form B-chains, yielding an AB block copolymer. The AB block copolymer had an Mn content of 16,000, a PDI content of 1.38, an acid value of 51.5 mg KOH / g, and a polymerization rate of approximately 100%. Furthermore, the Mn content of the B chain (total Mn - A chain Mn) is 5,800, and the acid value calculated from the blending value considering the polymerization rate is 116.4 mg KOH / g. After cooling the polymerization solution to room temperature, a mixture of 17.5 parts of 28% ammonia and 310 parts of water was added for neutralization, yielding a liquid (brown transparent liquid) containing binder B-1. The solid content of the obtained liquid is 30.8%, and the pH is 8.5. The content of methacrylate-derived units from biomaterials in the obtained binder B-1 (polymer) is 92.1%. Furthermore, the biomass of binder B-1 (polymer) is 55.1%, and the carbon dioxide absorption is 1,313 g / 1,000 g. The liquid containing binder B-1 was diluted 10 times with pure water to prepare a sample. Then, the average particle size of the emulsion particles in the sample was measured using a particle size distribution measuring device, and it was found to be 48.6 nm.

[0137] (Synthetic Examples 15-19) Except for the various materials of the types and amounts (unit: parts) shown in Table 8, all other liquids containing adhesives B-2 to B-6 were obtained in the same manner as in the aforementioned synthesis example 14. The physical properties of the obtained adhesive components are shown in Table 8.

[0138] [Table 8] Implementing a synthetic example 14 15 16 17 18 19 Adhesive B-1 B-2 B-3 B-4 B-5 B-6 solvent BDG 360.2 360.2 351.7 180.1 178.5 179.2 MPG 180.1 178.5 179.2 iodine 1.5 1.5 1.5 1.5 0.8 1.5 V-70 5.5 5.5 5.5 5.5 2.8 5.5 NIS 0.3 0.3 0.3 0.3 0.2 0.3 A chain THFMA 124.3 124.3 112.3 102.5 112.3 105.8 IBXMA 50.5 27.8 35.7 27.8 LMA 36.8 StMA 50.5 34.5 34.5 69.2 Mn 10,200 11,500 10,600 11,000 19,100 12,000 PDI 1.29 1.27 1.3 1.31 1.39 1.24 B-Chain THFMA 86.8 86.8 86.8 80.2 86.8 48.5 EMA 33.4 MAA 22.6 22.6 15.9 17.6 15.9 18.1 Mn 5,800 7,300 6,500 6,900 6,500 5,200 Acid value (mgKOH / g) 116.4 110 78.7 90.6 80.2 94.8 All Mn 16,000 18,800 17,100 17,900 25,600 17,200 PDI 1.38 1.31 1.34 1.37 1.48 1.28 Acid value (mgKOH / g) 51.5 51.5 37.1 41.7 37.1 43 Neutralizing agent 28% ammonia solution 17.5 17.5 12.4 13.7 NaOH 8 8.5 Solid content (%) 30.8 30.1 30.2 30.2 29.7 30.5 pH 8.5 8.6 8.7 8.8 9.5 9.7 Number average particle size (nm) 48.6 62.9 67.1 56.5 86.9 65 Methacrylic acid derived from biological materials Content (%) of ester-derived building blocks 92.1 92.1 94.3 93.6 94.3 93.4 Biomass (%) 55.1 57.4 58.6 57.9 58.6 57.7 Carbon dioxide absorption (g / 1,000g) 1,313 1,377 1,418 1,405 1,418 1,408 Environmental protection 〇 〇 〇 〇 〇 〇

[0139] <Ink (2) Preparation> (Examples 28-35) Prepare pigment dispersion-10 prepared in Example 10, binder components B-1 to B-6 prepared in Synthesis Examples 14 to 19, and binders B-7 and B-8 as shown below.

[0140] [Adhesive B-7: Amine Ester Aqueous Dispersion] A polyurethane ester formed from isophorone diisocyanate / polyhexamethylene carbonate diol / dimethylolbutyric acid / hydrazine is neutralized with triethylamine to obtain an adhesive component derived from petroleum materials. The acid value was 34.2 mg KOH / g, the number-average particle size was 42.2 nm, and the solid content was 25%.

[0141] [Adhesive B-8: Styrene-Acrylic Emulsion] An ammonia-neutralized product of a styrene-acrylic acid-methoxyethyl acrylate copolymer with Mn of 3,000 and an acid value of 260 mg KOH / g was used as a protective colloid to polymerize styrene with butyl acrylate to obtain a protective colloidal emulsion (derived from an adhesive component of petroleum materials). Styrene-acrylate-methoxyethyl acrylate copolymer / styrene / butyl acrylate = 30 / 30 / 40 (mass ratio), quantity average particle size shown at 105 nm, solids content shown at 43%.

[0142] The ink was prepared by mixing 100 parts of the following components: 4 parts pigment dispersion-10, 4 parts binder (solids), 0.1 parts surfactant (SURFYNOL S465), 0.7 parts wax (ethylene-acrylic acid ionomer, trade name "CHEMIPEARL W300", manufactured by Mitsui Chemicals), 12.0 parts propylene glycol, and water (the remainder). After thorough mixing, the mixture was filtered through a 10 μm pore size membrane filter to prepare inkjet ink. The characteristics of each ink (average particle size and viscosity of the pigment immediately after preparation and after storage at 70°C for one week) are shown in Table 9. The "Evaluation" criteria in Table 9 are as follows. ○: Even after being stored at 70°C for one week, the average particle size and viscosity of the pigment did not change significantly. △: Even after being stored at 70°C for 1 week, the average particle size of the pigment does not change significantly, but the viscosity increases. ×: Although the pigment is slightly dispersed, if it is stored at 70°C for 1 week, the average particle size or viscosity of the pigment will increase.

[0143] [Table 9] Adhesive Immediately after modulation After being placed at 70℃ for 1 week evaluate Number average particle size (nm) viscosity (mPa·s) Number average particle size (nm) viscosity (mPa·s) Example 28 B-1 116.4 3.99 116.9 3.96 〇 Example 29 B-2 116.4 3.63 116.4 3.66 〇 Example 30 B-3 116.3 3.56 116.4 3.55 〇 Example 31 B-4 116.3 3.65 116.4 3.64 〇 Example 32 B-5 116.4 3.64 116.4 3.63 〇 Example 33 B-6 116.5 3.55 116.4 3.61 〇 Example 34 B-7 116.5 3.32 116.4 3.19 〇 Example 35 B-8 116.4 3.86 118.6 4.13 △

[0144] (Examples 36-39) Except for replacing pigment dispersion-10 with pigment dispersion-14 to 16, the inkjet inks were prepared in the same manner as in Example 30 (Examples 36 to 38). Furthermore, using pigment dispersion-17, the inkjet ink was prepared in the same manner as in Example 28, by mixing 100 parts of ink with: pigment dispersion-17 (9 parts pigment content), binder B-1 (solid content) (4 parts), surfactant (SURFYNOL S465) (0.1 parts), propylene glycol (12.0 parts), and water (remaining) to form inkjet ink (Example 39). The characteristics of each ink (average particle size and viscosity of pigment immediately after preparation and after storage at 70°C for one week) are shown in Table 10. The "Evaluation" criteria in Table 10 are as follows. ○: Even after being stored at 70°C for one week, the average particle size and viscosity of the pigment did not change significantly. △: Even after being stored at 70°C for 1 week, the average particle size of the pigment does not change significantly, but the viscosity increases. ×: Although the pigment is slightly dispersed, if it is stored at 70°C for 1 week, the average particle size or viscosity of the pigment will increase.

[0145] [Table 10] Pigment dispersion Immediately after modulation After being placed at 70℃ for 1 week evaluate Number average particle size (nm) viscosity (mPa·s) Number average particle size (nm) viscosity (mPa·s) Example 30 -10 116.3 3.56 116.4 3.55 〇 Example 36 -14 151.8 3.61 151.4 3.66 〇 Example 37 -15 125.0 3.51 125.0 3.50 〇 Example 38 -16 109.1 3.51 109.1 3.50 〇 Example 39 -17 224.5 4.32 223.6 4.33 〇

[0146] Evaluation of Ink (2) (Implementation Examples 5-22) The inks obtained in Examples 28-39 were filled into ink cartridges and installed in an inkjet printer (trade name "MMP825H", manufactured by MASTERMIND) equipped with a plate heater. Then, images were printed onto each printing substrate heated by the plate heater, with the surface temperature set to 50°C, to obtain printed materials. The printing substrates used are shown below. • Polyvinyl chloride film (manufactured by 3M, 30μm) • OPP membrane (polypropylene film, manufactured by Futamura Chemicals, 50μm) • PET film (polyethylene terephthalate film, manufactured by Futamura Chemicals, 60μm)

[0147] (Exudative) Visually observe the ink ejection during printing and evaluate the ink ejection performance according to the evaluation criteria shown below. The results are shown in Table 11. 〇: It can be dispensed without any problems and can print good images. △: Confirmed that tiny droplets were scattered. ×: When it is spat out, the droplets splash and scatter, making the image messy.

[0148] (tightness) After thoroughly drying the printed material using a dryer, press the cellophane tape firmly onto the image and then peel it off. Visually observe the peeling of the image on the film and evaluate the adhesion of the image according to the evaluation criteria shown below. The results are shown in Table 11. ◎: No peeling at all. 〇: Slight peeling. △: The area to be peeled off is smaller than the area not to be peeled off. ×: The area stripped is larger than the area not stripped.

[0149] (Abrasion resistance (dry friction resistance and wet friction resistance)) Using a vibratory friction fastness tester (trade name "RT-300", manufactured by Daiei Scientific Co., Ltd.), a friction test was performed on the image surface 20 times with a 500g weight, using both dry and wet white cloth. The peeling of the image after the friction test was visually observed, and the abrasion resistance (dry and wet friction) of the image was evaluated according to the evaluation criteria shown below. The results are shown in Table 11. ◎: No peeling at all. 〇: Slight peeling. △: The area stripped is smaller than the area not stripped. ×: The area stripped is larger than the area not stripped.

[0150] [Table 11] ink Printed substrate Evomiting Tightness dry friction wet friction Implementation Example 5 Example 28 Polyvinyl chloride film 〇 ◎ ◎ 〇 Implementation Example 6 Example 28 OPP film 〇 ◎ ◎ 〇 Implementation Example 7 Example 28 PET film 〇 ◎ ◎ 〇 Implementation Example 8 Example 29 OPP film 〇 ◎ ◎ 〇 Implementation Example 9 Example 30 OPP film 〇 ◎ ◎ ◎ Implementation Example 10 Example 31 OPP film 〇 ◎ ◎ ◎ Implementation Example 11 Example 32 OPP film 〇 ◎ ◎ △ Implementation Example 12 Example 33 OPP film 〇 ◎ ◎ △ Implementation Example 13 Example 33 PET film 〇 ◎ ◎ ◎ Implementation Example 14 Example 34 OPP film 〇 ◎ ◎ ◎ Implementation Example 15 Example 34 PET film 〇 ◎ ◎ ◎ Implementation Example 16 Example 35 OPP film △ △ △ △ Implementation Example 17 Example 35 PET film △ 〇 △ △ Implementation Example 18 Example 36 OPP film 〇 ◎ ◎ 〇 Implementation Example 19 Example 37 OPP film 〇 ◎ ◎ 〇 Implementation Example 20 Example 38 OPP film 〇 ◎ ◎ 〇 Implementation Example 21 Example 39 OPP film 〇 〇 〇 〇 (Industrial applicability)

[0151] Using the aqueous pigment dispersion of the present invention provides an environmentally friendly water-based inkjet ink that offers stable and highly micro-dispersed pigments, and excellent image recording durability, gloss, color development, and adhesion to various printing substrates. Therefore, this water-based inkjet ink is suitable for outdoor display printing or high-volume, high-speed inkjet printing, and can also be effectively used as a water-based fast-drying printing ink, water-based coating, and water-based pen ink.

Claims

1. An aqueous pigment dispersion comprising: pigment, water, a water-soluble organic solvent, and a polymeric dispersant for dispersing the pigment, wherein the pigment content is 5-60% by mass, the water content is 20-80% by mass, the water-soluble organic solvent content is less than 30% by mass, and the polymeric dispersant content is 0.5-20% by mass; wherein, The aforementioned polymeric dispersant comprises: a constituent unit (i) derived from at least one of (meth)acrylic acid and itaconic acid, and a constituent unit (ii) derived from (meth)acrylate derived from biological materials, and is a polymer with an acid value of 30-250 mgKOH / g, a content of the aforementioned constituent unit (ii) of 50% by mass or more, a number average molecular weight of 1,000-30,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 2.5 or less, and at least a portion of the carboxyl groups being neutralized by alkali; the aforementioned (meth)acrylate derived from biological materials is selected from at least one of the group consisting of: ethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isoacrylate (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

2. As in claim 1, the aqueous pigment dispersion, wherein, The above-mentioned polymeric dispersant is a polymer that meets the following requirements (1) to (4): [Requirement (1)]: The content of the constituent units derived from methacrylic acid monomers is 90% by mass or more, and it contains an AB block copolymer of polymer chain A1 and polymer chain B1, wherein the above-mentioned methacrylic acid monomers are methacrylic acid and methacrylates that are esters of methacrylic acid; [Requirement (2)]: The above-mentioned polymer chain A1 contains 80% by mass or more of the constituent units (ii-a) derived from methacrylates derived from biological materials, and is a water-insoluble polymer block with a number average molecular weight of 1,000 to 10,000 and a molecular weight distribution of 1.6 or less; [Requirement (3)]: The above-mentioned polymer chain B1 contains the constituent units (ib) derived from methacrylic acid and contains 40% to 90% by mass of the constituent units (ii-b) derived from methacrylates derived from biological materials, and has an acid value of 50 to 260 mg KOH / g. Polymer blocks with a number average molecular weight of 1,000 to 10,000 and at least a portion of the carboxyl groups being neutralized by a base; [Requirement (4)]: with a number average molecular weight of 2,000 to 20,000 and a molecular weight distribution of less than 1.

6.

3. As in claim 2, the aqueous pigment dispersion, wherein, The aforementioned methacrylates derived from biological materials are selected from at least one of the following groups: ethyl methacrylate, tetrahydrofurfuryl methacrylate, isomethacrylate, octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate.

4. An aqueous pigment dispersion as described in any of claims 1 to 3, wherein, The base system that neutralizes at least a portion of the carboxyl group is selected from at least one of the following groups: ammonia, dimethylamine ethanol, 2-amino-1-propanol, sodium hydroxide, potassium hydroxide, lithium hydroxide, straight-chain aliphatic amines with 6 to 22 carbon atoms, branched aliphatic amines with 6 to 22 carbon atoms, and unsaturated aliphatic amines with 6 to 22 carbon atoms.

5. An aqueous inkjet ink comprising an aqueous pigment dispersion according to any one of claims 1 to 4.

6. The water-based inkjet ink of claim 5 further contains an adhesive component.

7. As in request item 6, water-based inkjet ink, wherein, The above adhesive components are polymers that meet the following requirements (5) to (9): [Requirement (5)]: The content of the constituent units derived from methacrylic acid monomers is more than 90% by mass, and it is an AB block copolymer containing polymer chain A2 and polymer chain B2; [Requirement (6)]: The above polymer chain A2 contains more than 80% by mass of the constituent units derived from methacrylate derived from biological materials, and is a water-insoluble polymer block with a number average molecular weight of 10,000 to 30,000 and a molecular weight distribution of less than 1.6; [Requirement (7)]: The above polymer chain B2 contains the constituent units derived from methacrylic acid, and contains 40 to 90% by mass of the constituent units derived from bio-methacrylate derived from biological materials, and is a polymer block with an acid value of 50 to 150 mgKOH / g, a number average molecular weight of 5,000 to 20,000, and at least a portion of the carboxyl groups are neutralized by alkali; [Requirement (8)]: The number average molecular weight is 15,000 to 50,000, and the molecular weight distribution is below 1.6; [Requirement (9)]: Particles with an average particle size of 10~200nm.

8. As in request item 7, water-based inkjet ink, wherein, The aforementioned methacrylates derived from biological materials are selected from at least one of the following groups: ethyl methacrylate, tetrahydrofurfuryl methacrylate, isomethacrylate, octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate.

9. A dried film, which is a film-like dried product of the aqueous inkjet ink of claim 7 or 8.