Aqueous dispersion containing acrylic resin for aqueous ink

Abstract

The purpose of the present invention is to provide a resin for inks which has satisfactory water resistance and weatherability and has a high biomass ratio. This resin for inks is characterized by being an acrylic resin for inks which has a biomass ratio of 10% or higher.

Description

[Technical Field]

[0001] The present invention relates to an acrylic resin for ink. An ink composition using the acrylic resin for ink of the present invention can be suitably used as an ink for, for example, inkjet ink, flexographic printing ink, offset printing ink, lithographic printing ink, gravure printing ink, screen printing ink, etc. The acrylic resin for ink of the present invention can be suitably used particularly as an aqueous inkjet ink and a gravure printing ink. [Background technology]

[0002] Energy and environmental policies, rising and volatile oil prices, and public / political awareness of the depletion of fossil fuel resources have created a need to find sustainable monomers derived from biomaterials. The use of biorenewable feedstocks has become increasingly important in recent years, as it allows manufacturers to reduce their carbon footprint and move towards a zero-carbon or even carbon-neutral carbon footprint.

[0003] For example, Patent Document 1 describes a biopolyurethane resin obtained by reacting a biopolyol component (A) with an isocyanate component (B). The biopolyol component (A) is a biopolyester polyol, which is a polymer of a polyfunctional alcohol component and a polyfunctional carboxylic acid component, and the biopolyol component (A) contains, as raw materials, a diol component (a) containing a plant-derived component and a dicarboxylic acid component (b) containing a plant-derived component. The diol component (a) contains plant-derived 1,2-propanediol and / or 1,3-propanediol, and the dicarboxylic acid component (b) contains adipic acid or dimer acid and plant-derived succinic acid. The biopolyurethane resin is characterized in that the plant-derived component content is 35% by mass or more per 100% by mass of the biopolyurethane resin. It also describes that printing inks using this highly biomass-rich biopolyurethane resin as a binder exhibit excellent adhesion to various plastic substrates, particularly bioplastic substrates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-172977 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it has been found that when polyurethane resins are used in printing inks, they have problems such as insufficient water resistance and weather resistance, and it has been difficult to obtain resins that are excellent in water resistance and weather resistance and have a high biomass content. An object of the present invention is to provide an ink resin that has good water resistance and weather resistance and has a high biomass content. [Means for solving the problem]

[0006] The present inventors have conducted research in light of the above-mentioned problems and have found that acrylic resins for inks with a biomass content of 10% or more have good water resistance and weather resistance, thereby completing the present invention. The present invention is configured as follows. [1] Acrylic resin for ink with a biomass content of 10% or more. [2] The acrylic resin for ink according to [1], which has a structural unit derived from a (meth)acrylate having a cyclic aliphatic group. [3] The acrylic resin for ink according to [2], wherein the (meth)acrylate having a cyclic aliphatic group is an ester of a cyclic aliphatic hydrocarbon having one hydroxyl group and (meth)acrylic acid. [4] The acrylic resin for ink according to [2] or [3], wherein the ratio of structural units derived from a (meth)acrylate having a cyclic aliphatic group to 100 parts by mass of the polymer is 30 parts by mass or more and 80 parts by mass or less. [5] The acrylic resin for ink according to [2] or [3], wherein the cyclic aliphatic group is a group derived from terpene. [6] The acrylic resin for ink according to any one of [1] to [3], which has an acid value of 20 mgKOH / g or less. [7] An aqueous dispersion containing the acrylic resin for ink according to any one of [1] to [6]. [8] An ink composition comprising the acrylic resin according to any one of [1] to [6] or the aqueous dispersion according to [7]. [9] The ink composition according to [8], further comprising a polymer wax.

[10] A laminate having a layer containing the acrylic resin for ink according to any one of [1] to [6] on a printing substrate.

[11] A method for producing a laminate, comprising the step of applying the ink composition according to [8] onto a printing substrate. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an acrylic resin for inks that has good water resistance and weather resistance and has a low environmental impact. Furthermore, the present invention provides an acrylic resin for inks that has good adhesion to substrates. In a preferred embodiment, the present invention provides an acrylic resin for inks that has excellent adhesion to olefin-based substrates such as biaxially oriented polypropylene (OPP) and also has good scratch resistance. DETAILED DESCRIPTION OF THE INVENTION

[0008] The acrylic resin for ink of the present disclosure is an acrylic resin with a biomass ratio of 10% or more. The biomass ratio of the present disclosure is calculated based on the following formula: Biomass ratio (%) = (biomass-derived carbon mass / total carbon mass) x 100 This measurement can be performed by applying the radiocarbon dating method, using accelerator mass spectrometry (AMS). 14 It can be determined by measuring the ratio of C and converting it. When a raw material with a known biomass degree is used, it is also possible to calculate the biomass degree from the resin composition. From the viewpoints of water resistance, weather resistance, and environmental impact, the acrylic resin of the present disclosure has a biomass degree of 10% or more, preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. There are no particular limitations on the upper limit of the biomass degree, and it may be 100%, but it may also be, for example, 90% or less, particularly 80% or less. That is, the biomass degree is preferably 20 to 100%, more preferably 30 to 90%, and even more preferably 40 to 80%.

[0009] <Acrylic resin> In this specification, the term "resin" is a broader concept than "polymer." A resin may be composed of, for example, one or more polymers, and may contain, as necessary, materials other than polymers, such as additives (preferably solidifying agents) such as ultraviolet absorbers, antioxidants, fillers, compatibilizers, and stabilizers. The acrylic resin of the present disclosure belongs to a group of resins having structural units derived from monomers having an ethylenic double bond, and includes polymers (acrylic polymers) having at least one or more structural units derived from acrylic monomers as the structural units derived from the monomers having an ethylenic double bond. The acrylic monomer refers to a monomer having an acryloyl group or a methacryloyl group, or a group in which a hydrogen atom in these groups has been replaced with another atom or atomic group (such as a malenoyl group, a fumaroyl group, a crotonoyl group, an itaconoyl group, or a citraconoyl group), or a derivative of such a monomer. The acrylic monomer of the present disclosure is preferably a monomer having an acroyl group or a methacryloyl group, in which the hydrogen atom in these groups is not replaced by another atom or atomic group, and such preferred monomers include (meth)acrylic acid and (meth)acrylic acid esters. The acrylic resin of the present disclosure may contain one or more acrylic polymers. The content of the acrylic polymer per 100 parts by mass of the acrylic resin of the present disclosure is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 90 parts by mass or more.

[0010] From the viewpoint of water resistance and weather resistance, the acrylic polymer contained in the acrylic resin of the present disclosure may be a polymer having 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more of structural units derived from an acrylic monomer per 100 parts by mass of the polymer. A structural unit derived from a monomer having an ethylenic double bond corresponds to a structure in which the ethylenically unsaturated double bond is opened (a structure in which the double bond (C=C) becomes a single bond (-CC-)).

[0011] A structural unit derived from an acrylic monomer corresponds to a structure in which the ethylenically unsaturated double bond of each monomer is opened (a structure in which the double bond (C=C) becomes a single bond (-CC-)) by the polymerization reaction of the acrylic monomer, for example. In the present invention, "(meth)acrylate" means "acrylate" or "methacrylate". "(meth)acrylic acid" means "acrylic acid" or "methacrylic acid". "(meth)acrylic" means "acrylic" or "methacrylic". Furthermore, "(meth)acryloyl" means "acryloyl" or "methacryloyl".

[0012] The acrylic polymer of the present disclosure has structural units derived from monomers having an ethylenic double bond, and the monomers having an ethylenic double bond may or may not contain monomers other than acrylic monomers, as long as they include at least one acrylic monomer. The monomer having an ethylenic double bond of the present disclosure and the acrylic monomer, which is one embodiment thereof, each include a monofunctional monomer and a polyfunctional monomer, and either of these can be used in the present invention. It is preferable to include at least a monofunctional monomer. The monofunctional monomer and the polyfunctional monomer may be used alone or in combination. The ratio of the monofunctional monomer to the polyfunctional monomer (monofunctional monomer / polyfunctional monomer) is preferably 100 / 0 to 50 / 50, more preferably 100 / 0 to 90 / 10, even more preferably 100 / 0 to 95 / 5, and may be 100 / 0.

[0013] <Monofunctional monomer> Specific examples of the monomers having an ethylenic double bond that fall under the category of monofunctional monomers will be described below. Among the monomers having an ethylenic double bond of the present disclosure, examples of monofunctional monomers include, but are not limited to, acid group-containing monomers, alkyl or alkenyl (meth)acrylates, (meth)acrylates having an aromatic group, hydroxyl group-containing (meth)acrylates, piperidine group-containing monomers, oxo group-containing monomers, fluorine atom- or chlorine atom-containing monomers, nitrogen atom-containing monomers, epoxy group-containing monomers, alkoxyalkyl (meth)acrylates, silane group-containing monomers, carbonyl group-containing monomers, aziridinyl group-containing monomers, styrene-based monomers, and addition-polymerizable oxazolines. These monomers having an ethylenic double bond may be used alone or in combination of two or more. The alkyl or alkenyl (meth)acrylate, the (meth)acrylate having an aromatic group, the hydroxyl group-containing (meth)acrylate, the alkoxyalkyl (meth)acrylate, and the aralkyl (meth)acrylate correspond to the acrylic monomer. The acid group-containing monomer, the piperidine group-containing monomer, the oxo group-containing monomer, the fluorine atom- or chlorine atom-containing monomer, the nitrogen atom-containing monomer, the epoxy group-containing monomer, the silane group-containing monomer, the carbonyl group-containing monomer, the aziridinyl group-containing monomer, and the like include those that correspond to acrylic monomers and those that do not correspond to acrylic monomers but have an ethylenic double bond. The styrene-based monomers and the addition-polymerizable oxazolines do not correspond to acrylic monomers but correspond to monomers having an ethylenic double bond.

[0014] Among the acid group-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include vinyl aliphatic mono- or dicarboxylic acids such as (meth)acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, and maleic anhydride; and carboxyl group-containing aliphatic monomers such as vinyl aliphatic dicarboxylic acid monoesters such as maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, and itaconic acid monobutyl ester. However, the present invention is not limited to these examples. Among the acid group-containing monomers of the present disclosure, examples of monomers not corresponding to acrylic monomers include vinyl aromatic carboxylic acids such as vinyl benzoic acid. However, the present invention is not limited to these examples. These acid group-containing monomers may be used alone or in combination of two or more. Among these acid group-containing monomers, vinyl aliphatic mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid are preferred from the viewpoint of improving the dispersion stability of emulsion particles, and vinyl aliphatic monocarboxylic acids such as acrylic acid and methacrylic acid are more preferred.

[0015] As long as the monomers other than the acid group-containing monomer have a predetermined biomass degree, the biomass degree of the acid group-containing monomer of the present disclosure (particularly the acid group-containing monomer as an acrylic monomer) may be 0%. However, from the viewpoint of environmental impact, the biomass degree of the acid group-containing monomer is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. From the viewpoints of adhesion, scratch resistance, and environmental impact, (meth)acrylic acid and itaconic acid having the above biomass degrees are more preferred.

[0016] Examples of the alkyl or alkenyl (meth)acrylate of the present disclosure include (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched alkyl group, and (meth)acrylates having a cyclic aliphatic group. As the alkyl or alkenyl (meth)acrylate, it is preferable to use a (meth)acrylate having a cyclic aliphatic group from the viewpoint of adhesion to a substrate, particularly adhesion to an olefin-based substrate such as biaxially oriented polypropylene (OPP). If the monomer other than the alkyl or alkenyl (meth)acrylate has a predetermined biomass degree, the biomass degree of the alkyl or alkenyl (meth)acrylate of the present disclosure may be 0%, but from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. By satisfying the above range, an ink can be obtained that is excellent in water resistance, weather resistance, and adhesion to the substrate, and is also preferable from the viewpoint of environmental impact.

[0017] The (meth)acrylate having a linear alkyl group according to the present disclosure preferably has a linear alkyl group having 1 to 30 carbon atoms, more preferably has a linear alkyl group having 1 to 25 carbon atoms, and even more preferably has a linear alkyl group having 1 to 20 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (also referred to as lauryl (meth)acrylate), tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate. From the viewpoint of adhesion and scratch resistance, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate are preferred.

[0018] As long as the (meth)acrylate having a linear alkyl group has a predetermined biomass degree, the biomass degree of the (meth)acrylate having a linear alkyl group of the present disclosure may be 0%, but from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. From the viewpoints of adhesion, scratch resistance, and environmental impact, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (also referred to as lauryl (meth)acrylate), tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate, which have the above-mentioned biomass degree, are preferred, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate are more preferred, and ethyl (meth)acrylate and butyl (meth)acrylate are even more preferred.

[0019] The (meth)acrylate having a branched alkyl group of the present disclosure preferably has a branched alkyl group having 4 to 40 carbon atoms, more preferably has a branched alkyl group having 4 to 30 carbon atoms, and even more preferably has a branched alkyl group having 4 to 20 carbon atoms. Specific examples include isopropyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, isostearyl (meth)acrylate, 1-methyl-1-ethyl-5-methylhexyl (meth)acrylate (ester of hydrogenated linalool and (meth)acrylic acid), 2-isopropyl-5-methylhexyl (meth)acrylate (ester of hydrogenated lavandulol and (meth)acrylic acid), 3,7-dimethyloctyl (meth)acrylate, and the like. Examples include acrylates (esters of hydrogenated geraniol, hydrogenated nerol, or hydrogenated citronellol with (meth)acrylic acid), and from the viewpoint of adhesion and scratch resistance, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, and isostearyl (meth)acrylate are preferred, and isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isostearyl (meth)acrylate are more preferred.

[0020] As long as the monomer other than the (meth)acrylate having a branched alkyl group has a predetermined biomass degree, the biomass degree of the (meth)acrylate having a branched alkyl group of the present disclosure may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more.

[0021] The (meth)acrylate having a cycloaliphatic group of the present disclosure preferably has a cycloaliphatic group having 5 to 20 carbon atoms, more preferably has a cycloaliphatic group having 5 to 15 carbon atoms, and even more preferably has a cycloaliphatic group having 5 to 12 carbon atoms. The (meth)acrylate having a cyclic aliphatic group is preferably an ester of a cyclic aliphatic hydrocarbon having one hydroxyl group and (meth)acrylic acid, and specific examples thereof include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, thuyanyl (meth)acrylate, 1-isopropyl-4-methylcyclohexyl (meth)acrylate (ester of hydrogenated terpinen-4-ol and (meth)acrylic acid), 1-methyl-4-isopropylcyclohexyl (meth)acrylate (ester of hydrogenated terpeneol and (meth)acrylic acid), 2-isopropyl-5-methylcyclohexyl (meth)acrylate (ester of hydrogenated menthol and (meth)acrylic acid), dicyclopentanyl (meth)acrylate, and dicyclopentenyl (meth)acrylate. (Meth)acrylates having a cyclic saturated aliphatic group are preferred, particularly cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, etc., and cyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate are more preferred. These (meth)acrylates having a cyclic aliphatic group can be used alone or in combination.

[0022] As long as the monomer other than the (meth)acrylate having a cycloaliphatic group has a predetermined biomass degree, the biomass degree of the (meth)acrylate having a cycloaliphatic group of the present disclosure may be 0%, but from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. From the viewpoints of water resistance, weather resistance, adhesion to substrates, and environmental impact, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate having the above biomass degree are preferred, and cyclohexyl (meth)acrylate and isobornyl (meth)acrylate are more preferred.

[0023] Examples of the (meth)acrylate having an aromatic group of the present disclosure include, but are not limited to, aralkyl (meth)acrylates such as benzyl (meth)acrylate, phenylethyl (meth)acrylate, methylbenzyl (meth)acrylate, and naphthylmethyl (meth)acrylate; phenoxyethyl (meth)acrylate; and the like. These (meth)acrylates having an aromatic group may be used alone or in combination of two or more. As the (meth)acrylate having an aromatic group, aralkyl (meth)acrylates are preferred, and aralkyl (meth)acrylates having an aralkyl group having 7 to 18 carbon atoms are more preferred. If a monomer other than the (meth)acrylate having an aromatic group has a predetermined biomass degree, the biomass degree of the (meth)acrylate having an aromatic group of the present disclosure may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more.

[0024] Examples of hydroxyl group-containing (meth)acrylates of the present disclosure include, but are not limited to, hydroxyl group-containing (meth)acrylates having an ester group containing 1 to 18 carbon atoms, such as 2-hydroxyethyl (meth)acrylate (also referred to as ethylene glycol (meth)acrylate), 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. These hydroxyl group-containing (meth)acrylates may be used alone or in combination of two or more. In this specification, the number of carbon atoms in the ester group means the number of carbon atoms in the portion derived from the alcohol in the ester composed of a carboxylic acid and an alcohol. If the monomer other than the hydroxyl group-containing (meth)acrylate has a predetermined biomass degree, the biomass degree of the hydroxyl group-containing (meth)acrylate of the present disclosure may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more.

[0025] Among the piperidine group-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyl-1-methoxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-1,2,6,6-pentamethylpiperidine, 4- ... Examples of piperidine group-containing (meth)acrylates having four methyl groups at the 2- and 6-positions include, but are not limited to, 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, and 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine. Among the piperidine group-containing monomers of the present disclosure, examples of monomers that do not correspond to acrylic monomers include, but are not limited to, piperidine group-containing monomers having four methyl groups at the 2- and 6-positions, such as 2,2,6,6-tetramethyl-4-vinyloxypiperidine. These piperidine group-containing monomers may be used alone or in combination of two or more. When the acrylic polymer of the present disclosure uses a piperidine group-containing monomer, the piperidine group-containing monomer is not considered to be a nitrogen atom-containing monomer. As long as the monomers other than the piperidine group-containing monomer have a predetermined biomass degree, the biomass degree of the piperidine group-containing monomer of the present disclosure (particularly the piperidine group-containing monomer as an acrylic monomer) may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more.

[0026] Among the oxo group-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include (di- or poly-)ethylene glycol (methoxy or ethoxy) (meth)acrylates such as ethylene glycol methoxy (meth)acrylate, diethylene glycol (meth)acrylate, diethylene glycol methoxy (meth)acrylate, diethylene glycol ethoxy (meth)acrylate (also referred to as ethyl carbitol (meth)acrylate), and polyethylene glycol ethoxy (meth)acrylate (also referred to as ethoxy polyethylene glycol (meth)acrylate), but are not limited to these examples. Among the oxo group-containing monomers of the present disclosure, examples of monomers not corresponding to acrylic monomers include (2-methoxyethyl) vinyl ether, but are not limited to these examples. These oxo group-containing monomers may be used alone or in combination of two or more. Note that the oxo group-containing monomers of the present disclosure do not include the above-mentioned hydroxyl group-containing monomers or the alkoxyalkyl (meth)acrylates described below. As long as the monomers other than the oxo group-containing monomer have a predetermined biomass degree, the biomass degree of the oxo group-containing monomer of the present disclosure (particularly the oxo group-containing monomer as an acrylic monomer) may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more.

[0027] Among the fluorine atom- or chlorine atom-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include, but are not limited to, fluorine atom-containing alkyl (meth)acrylates having 2 to 10 (preferably 2 to 6) carbon atoms in the ester group, such as trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, and heptadecafluorooctylethyl (meth)acrylate; and chlorine atom-containing alkyl (meth)acrylates having 2 to 6 carbon atoms in the ester group, such as chloroethyl (meth)acrylate. Examples of fluorine atom- or chlorine atom-containing monomers that do not correspond to acrylic monomers include, but are not limited to, pentafluoroethyl trifluorovinyl ether. These fluorine atom- or chlorine atom-containing monomers may be used alone or in combination of two or more. As long as a monomer other than a fluorine atom- or chlorine atom-containing monomer has a predetermined biomass degree, the biomass degree of the fluorine atom- or chlorine atom-containing monomer of the present disclosure (particularly a fluorine atom- or chlorine atom-containing monomer as an acrylic monomer) may be 0%, but from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more.

[0028] Among the nitrogen atom-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include N-mono C monomers such as (meth)acrylamide; N-monomethyl(meth)acrylamide, N-monoethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, Nn-propyl(meth)acrylamide, and N-isopropyl(meth)acrylamide. 1-6 Alkyl (meth)acrylamide or N,N-diC 1-6 C such as alkyl(meth)acrylamide; methylenebis(meth)acrylamide 1-4Alkylenebis(meth)acrylamide; N-mono C such as N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, dimethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and diacetone(meth)acrylamide 1-6 Alkyl (meth)acrylamides containing hydroxy groups, C 1-6 Alkoxy group, diC 1-2 Alkylamino group, or C 2-4 The acyl group is 1-6 (Meth)acrylamide compounds such as compounds bonded to alkyl groups; C such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate 2-6 Alkyl (meth)acrylate, mono or di C 1-4 The alkylamino group is 2-6 Compounds bonded to alkyl groups, Examples of the nitrogen atom-containing monomers of the present disclosure that do not correspond to acrylic monomers include, but are not limited to, N-vinylpyrrolidone, (meth)acrylonitrile, and the like. These nitrogen atom-containing monomers may be used alone or in combination of two or more. The nitrogen atom-containing monomers of the present disclosure do not include the piperidine group-containing monomers. As long as the monomers other than the nitrogen-atom-containing monomer have a predetermined biomass degree, the biomass degree of the nitrogen-atom-containing monomer of the present disclosure (particularly the nitrogen-atom-containing monomer as an acrylic monomer) may be 0%, but from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more.

[0029] Among the epoxy group-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include, but are not limited to, epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and α-methylglycidyl (meth)acrylate. Among the epoxy group-containing monomers of the present disclosure, examples of monomers not corresponding to acrylic monomers include, but are not limited to, glycidyl allyl ether. These epoxy group-containing monomers may be used alone or in combination of two or more. As long as the monomers other than the epoxy group-containing monomer have a predetermined biomass degree, the biomass degree of the epoxy group-containing monomer of the present disclosure (particularly the epoxy group-containing monomer as an acrylic monomer) may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more.

[0030] Examples of the alkoxyalkyl (meth)acrylate of the present disclosure include C alkyl (meth)acrylates such as methoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate (preferably 3-methoxybutyl (meth)acrylate), and ethoxybutyl (meth)acrylate. 1-4 Alkyl (meth)acrylate, C 1-4 The alkoxy is 1-4 Examples of alkoxyalkyl (meth)acrylates include, but are not limited to, compounds bonded to an alkyl group. These alkoxyalkyl (meth)acrylates may be used alone or in combination of two or more. If the monomer other than the alkoxyalkyl (meth)acrylate has a predetermined biomass degree, the biomass degree of the alkoxyalkyl (meth)acrylate of the present disclosure may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more.

[0031] Among the silane group-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include (meth)acryloyloxy C such as γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropylhydroxysilane, and γ-(meth)acryloyloxypropylmethylhydroxysilane. 2-6 Examples of the silane group-containing monomers of the present disclosure that do not correspond to acrylic monomers include, but are not limited to, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(methoxyethoxy)silane, 2-styrylethyltrimethoxysilane, and vinyltrichlorosilane, but are not limited to, examples. These silane group-containing monomers may be used alone or in combination of two or more. As long as the monomers other than the silane group-containing monomer have a predetermined biomass degree, the biomass degree of the silane group-containing monomer of the present disclosure (particularly the silane group-containing monomer as an acrylic monomer) may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more.

[0032] Among the carbonyl group-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include, but are not limited to, (meth)acryloxyalkylpropenal, acetonyl (meth)acrylate, diacetone (meth)acrylate, 2-hydroxypropyl (meth)acrylate acetylacetate, butanediol-1,4-acrylate acetylacetate, and 2-(acetoacetoxy)ethyl (meth)acrylate. Among the carbonyl group-containing monomers of the present disclosure, examples of monomers not corresponding to acrylic monomers include, but are not limited to, acrolein, humyl styrene, and vinyl ethyl ketone. These carbonyl group-containing monomers may be used alone or in combination of two or more. As long as the monomers other than the carbonyl group-containing monomer have a predetermined biomass degree, the biomass degree of the carbonyl group-containing monomer of the present disclosure (particularly the carbonyl group-containing monomer as an acrylic monomer) may be 0%, but from the viewpoint of environmental impact, the biomass degree is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more.

[0033] Among the aziridinyl group-containing monomers of the present disclosure, examples of monomers corresponding to acrylic monomers include, but are not limited to, (meth)acryloylaziridine, 2-aziridinylethyl (meth)acrylate, etc. These aziridinyl group-containing monomers may be used alone or in combination of two or more. As long as the monomers other than the aziridinyl group-containing monomer have a predetermined biomass degree, the biomass degree of the aziridinyl group-containing monomer of the present disclosure (particularly the aziridinyl group-containing monomer as an acrylic monomer) may be 0%. However, from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more.

[0034] Examples of styrene-based monomers of the present disclosure include, but are not limited to, styrene, α-methylstyrene, p-methylstyrene, tert-methylstyrene, chlorostyrene, and vinyltoluene. These styrene-based monomers may be used alone or in combination of two or more. The styrene-based monomer may have a functional group such as an alkyl group (e.g., methyl group, tert-butyl group), a nitro group, a nitrile group, an alkoxyl group, an acyl group, a sulfone group, a hydroxyl group, or a halogen atom on the benzene ring. Among the styrene-based monomers, styrene is preferred from the viewpoint of enhancing water resistance. As long as the monomer other than the styrene-based monomer has a predetermined biomass degree, the biomass degree of the styrene-based monomer of the present disclosure may be 0%.

[0035] Examples of the addition-polymerizable oxazoline of the present disclosure include, but are not limited to, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These addition-polymerizable oxazolines may be used alone or in combination of two or more. Among these addition-polymerizable oxazolines, 2-isopropenyl-2-oxazoline is preferred because it is easily available. As long as the monomer other than the addition-polymerizable oxazoline has a predetermined biomass degree, the biomass degree of the addition-polymerizable oxazoline of the present disclosure may be 0%.

[0036] It is preferred that at least one of the monofunctional monomers has a biomass content of more than 0% (for example, 10% or more, preferably 30% or more, more preferably 50% or more). The monofunctional monomer having a biomass degree of more than 0% is preferably at least one selected from an acid group-containing monomer, an alkyl or alkenyl (meth)acrylate, a (meth)acrylate having an aromatic group, a hydroxyl group-containing (meth)acrylate, a piperidine group-containing monomer, an oxo group-containing monomer, a fluorine atom- or chlorine atom-containing monomer, a nitrogen atom-containing monomer, an epoxy group-containing monomer, an alkoxyalkyl (meth)acrylate, a silane group-containing monomer, a carbonyl group-containing monomer, an aziridinyl group-containing monomer, etc., more preferably at least one selected from an acid group-containing monomer, an alkyl or alkenyl (meth)acrylate, a hydroxyl group-containing (meth)acrylate, an oxo group-containing monomer, an alkoxyalkyl (meth)acrylate, and a carbonyl group-containing monomer, even more preferably an acid group-containing monomer and an alkyl (meth)acrylate, and particularly preferably an alkyl (meth)acrylate.

[0037] In another preferred embodiment, the monofunctional monomer having a biomass ratio of more than 0% is a monomer corresponding to a monomer having a plant-derived (meth)acryloyl group (hereinafter referred to as a bio(meth)acryloyl group) or a monomer having a group derived from a plant-derived alcohol (hereinafter referred to as a bioalcohol) among the above-mentioned monofunctional monomers. The use of these monomers allows for maintaining good ink properties even when the biomass ratio of the acrylic polymer is increased. The bio(meth)acryloyl group is a group that can be introduced from plant-derived glycerin. Bioalcohols include bioalkanols such as bioethanol, biopropanol, and biobutanol, and terpene-derived alcohols, all of which are commercially available. Examples of the monomer having a bio(meth)acryloyl group include the above-mentioned monofunctional monomers classified as acrylic monomers. Examples of monomers having a group derived from bioalcohol include esters of bioalcohol and (meth)acrylic acid, specifically (meth)acrylates having a linear or branched alkyl group, where the linear or branched alkyl group is derived from bioalkanol, and (meth)acrylates having a branched alkyl group or a cyclic aliphatic group, where the branched alkyl group or the cyclic aliphatic group is a group derived from terpene. The (meth)acrylic acid that forms an ester with bioalcohol may be bio(meth)acrylic acid or petroleum-derived (meth)acrylic acid.

[0038] Monofunctional monomers having a biomass ratio of greater than 0% are preferably monomers having a bio(meth)acryloyl group, (meth)acrylates having a terpene-derived branched alkyl group, or (meth)acrylates having a terpene-derived cyclic aliphatic group. Using a plant-derived acryloyl group can increase the biomass ratio of many types of monomer components when forming an acrylic polymer from a copolymer composed of multiple acrylic monomers, making it easy to improve the biomass ratio. Furthermore, in the case of (meth)acrylates having a terpene-derived group, because terpenes have a large number of carbon atoms, simply making one chemical species plant-derived can make a large amount of carbon plant-derived, making it easy to improve the biomass ratio.

[0039] As the monofunctional monomer having a biomass degree of more than 0%, (meth)acrylates having a branched alkyl group derived from terpene, (meth)acrylates having a cyclic aliphatic group derived from terpene, etc. are more preferred, and (meth)acrylates having a cyclic aliphatic group derived from terpene are particularly preferred. When a (meth)acrylate having a branched alkyl group or a cyclic aliphatic group derived from terpene is used, one or more of adhesion, adhesive tape peeling resistance, and weather resistance are improved compared to when an alkyl (meth)acrylate not derived from terpene is used, and adhesion is particularly improved.

[0040] Examples of (meth)acrylates having a branched alkyl group derived from terpene include 1-methyl-1-ethyl-5-methylhexyl (meth)acrylate (ester of hydrogenated linalool and (meth)acrylic acid), 2-isopropyl-5-methylhexyl (meth)acrylate (ester of hydrogenated lavandulol and (meth)acrylic acid), and 3,7-dimethyloctyl (meth)acrylate (ester of hydrogenated geraniol, hydrogenated nerol, or hydrogenated citronellol and (meth)acrylic acid). Examples of (meth)acrylates having a cyclic aliphatic group derived from a terpene include bornyl (meth)acrylate, isobornyl (meth)acrylate, thuyanyl (meth)acrylate, 1-isopropyl-4-methylcyclohexyl (meth)acrylate (ester of hydrogenated terpinen-4-ol and (meth)acrylic acid), 1-methyl-4-isopropylcyclohexyl (meth)acrylate (ester of hydrogenated terpeneol and (meth)acrylic acid), and 2-isopropyl-5-methylcyclohexyl (meth)acrylate (ester of hydrogenated menthol and (meth)acrylic acid), with bornyl (meth)acrylate and isobornyl (meth)acrylate being preferred.

[0041] Suitable monofunctional monomers of the present disclosure include, for example, one or more selected from alkyl or alkenyl (meth)acrylates (such as (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched alkyl group, or (meth)acrylates having a cyclic aliphatic group), hydroxyl group-containing (meth)acrylates, piperidine group-containing monomers, acid group-containing monomers, oxo group-containing monomers, fluorine atom- or chlorine atom-containing monomers, nitrogen atom-containing monomers, epoxy group-containing monomers, and styrene-based monomers. Preferably, the monomer contains one or more selected from (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched alkyl group, (meth)acrylates having a cyclic aliphatic group, hydroxyl group-containing (meth)acrylates, piperidine group-containing monomers, and acid group-containing monomers. More preferably, the monomer contains one or more selected from (meth)acrylates having a cyclic aliphatic group and hydroxyl group-containing (meth)acrylates. Particularly preferably, the monomer contains at least a (meth)acrylate having a cyclic aliphatic group. These monomers may be used alone or in combination of two or more. From the viewpoint of further improving adhesion to corona-treated PET, OPP, or the like, a preferred monofunctional monomer can be selected. Among these, piperidine group-containing monomers, nitrogen atom-containing monomers, and addition-polymerizable oxazolines are preferred. Among these, piperidine group-containing monomers and addition-polymerizable oxazolines are more preferred, with 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, and 2-isopropenyl-2-oxazoline being even more preferred. Furthermore, the inclusion of a hydroxyl group-containing (meth)acrylate as a monofunctional monomer facilitates the production of emulsion particles free of coarse particles, and from the viewpoint of improving the ejection stability of inks containing the emulsion particles, it is preferred to include a hydroxyl group-containing (meth)acrylate.

[0042] The acrylic polymer of the present disclosure may contain structural units derived from acrylic monomers (particularly acrylic monomers as monofunctional monomers) in an amount of 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, per 100 parts by mass of the acrylic polymer of the present disclosure. The biomass content of the acrylic polymer of the present disclosure is 10% or more, preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. By satisfying the above ranges, an ink can be obtained that is excellent in water resistance and weather resistance and is also favorable from the standpoint of environmental impact.

[0043] The content of structural units derived from an acid group-containing monomer (preferably an acid group-containing monomer as an acrylic monomer) in 100 parts by mass of the acrylic polymer of the present disclosure may be 0 parts by mass, but from the viewpoints of improving polymerization stability, storage stability, ejection stability, and adhesion, it is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, and from the viewpoints of ejection stability and low viscosity, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less (i.e., preferably 0 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, even more preferably 0.5 to 8 parts by mass, and particularly preferably 1 to 6 parts by mass).

[0044] The content of structural units derived from alkyl or alkenyl (meth)acrylate in 100 parts by mass of the acrylic polymer of the present disclosure is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 40 parts by mass or more or 60 parts by mass or more, from the viewpoint of improving abrasion resistance, adhesion, and blocking resistance; and from the viewpoint of improving abrasion resistance, adhesion, and blocking resistance, it is preferably 95 parts by mass or less or 90 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 75 parts by mass or less, and even more preferably 70 parts by mass or less (i.e., 10 to 95 parts by mass is preferred, 15 to 90 parts by mass is more preferred, 20 to 80 parts by mass is even more preferred, 40 to 75 parts by mass is particularly preferred, and 60 to 70 parts by mass is most preferred). The content of the structural unit derived from a (meth)acrylate having a linear alkyl group in 100 parts by mass of the acrylic polymer of the present disclosure may be 0 parts by mass, but from the viewpoint of improving abrasion resistance, it is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and from the viewpoint of improving adhesion and blocking resistance, it is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 30 parts by mass or less (i.e., preferably 0 to 70 parts by mass, more preferably 10 to 65 parts by mass, even more preferably 15 to 60 parts by mass, and particularly preferably 20 to 30 parts by mass).

[0045] The content of the structural unit derived from a (meth)acrylate having a branched alkyl group in 100 parts by mass of the acrylic polymer of the present disclosure may be 0 parts by mass, but from the viewpoints of low viscosity and discharge stability, it is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and from the viewpoints of improving adhesion and blocking resistance, it is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 30 parts by mass or less (i.e., preferably 0 to 70 parts by mass, more preferably 10 to 65 parts by mass, even more preferably 15 to 60 parts by mass, and particularly preferably 20 to 30 parts by mass).

[0046] From the viewpoint of improving adhesion, the content of the structural unit derived from a (meth)acrylate having a cyclic aliphatic group in 100 parts by mass of the acrylic polymer of the present disclosure may be 30 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, and may be 95 parts by mass or less, preferably 90 parts by mass or less, and more preferably 85 parts by mass or less (i.e., preferably 30 to 95 parts by mass, more preferably 35 to 95 parts by mass, even more preferably 40 to 90 parts by mass, and particularly preferably 45 to 85 parts by mass).

[0047] In the acrylic polymer of the present disclosure, the content of structural units derived from a (meth)acrylate having a cyclic aliphatic group in 100 parts by mass of structural units derived from an alkyl or alkenyl (meth)acrylate may be 30 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, from the viewpoint of improving adhesion, and may be 95 parts by mass or less, preferably 90 parts by mass or less, and more preferably 85 parts by mass or less (i.e., 30 to 95 parts by mass is preferred, 35 to 95 parts by mass is more preferred, 40 to 90 parts by mass is even more preferred, and 45 to 85 parts by mass is particularly preferred).

[0048] The content ratio of the hydroxyl group-containing (meth)acrylate in 100 parts by mass of the acrylic polymer of the present disclosure is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, from the viewpoint of improving adhesion and ejection stability, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, from the viewpoint of reducing viscosity and stability over time (i.e., preferably 0.1 to 30 parts by mass, more preferably 0.5 to 25 parts by mass, and even more preferably 1 to 20 parts by mass).

[0049] The content ratio of the piperidine group-containing monomer (preferably the piperidine group-containing monomer as an acrylic monomer) derived from 100 parts by mass of the acrylic polymer of the present disclosure may be 0 parts by mass, but from the viewpoint of further improving weather resistance and adhesion, it is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 3 parts by mass or more or 5 parts by mass or more, and from the viewpoint of improving water resistance, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less (i.e., preferably 0 to 30 parts by mass, more preferably 0.1 to 30 parts by mass, more preferably 0.2 to 20 parts by mass, even more preferably 0.5 to 15 parts by mass, even more preferably 3 to 10 parts by mass, and most preferably 5 to 10 parts by mass).

[0050] The content ratio derived from the styrene-based monomer in 100 parts by mass of the acrylic polymer of the present disclosure may be 0 parts by mass, but from the viewpoint of improving gloss and water resistance, it is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and from the viewpoint of light fastness and yellowing resistance, it is preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 50 parts by mass or less (i.e., 0 to 60 parts by mass is preferred, 10 to 60 parts by mass is more preferred, 15 to 55 parts by mass is even more preferred, and 20 to 50 parts by mass is particularly preferred).

[0051] The proportion of structural units derived from monomers other than those mentioned above, i.e., (meth)acrylates having an aromatic group, oxo group-containing monomers (preferably oxo group-containing monomers as acrylic monomers), fluorine atom- or chlorine atom-containing monomers (preferably fluorine atom- or chlorine atom-containing monomers as acrylic monomers), nitrogen atom-containing monomers (preferably nitrogen atom-containing monomers as acrylic monomers), epoxy group-containing monomers (preferably epoxy group-containing monomers as acrylic monomers), alkoxyalkyl (meth)acrylates, silane group-containing monomers (preferably silane group-containing monomers as acrylic monomers), carbonyl group-containing monomers (preferably carbonyl group-containing monomers as acrylic monomers), aziridinyl group-containing monomers (preferably aziridinyl group-containing monomers as acrylic monomers), and addition-polymerizable oxazolines, may be, for example, 0 parts by mass or more, or 10 parts by mass or more, and 50 parts by mass or less, or 30 parts by mass or less, per 100 parts by mass of the acrylic polymer (i.e., 0 to 50 parts by mass is preferred, and 10 to 30 parts by mass is more preferred).

[0052] <Polyfunctional Monomer> The monomer having an ethylenic double bond also includes a polyfunctional monomer. The polyfunctional monomer may or may not be an acrylic monomer, but is preferably an acrylic monomer. Examples of polyfunctional monomers that can be used as acrylic monomers according to the present disclosure include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, ethylene oxide-modified 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, propylene oxide-modified neopentyl glycol di(meth)acrylate, triptyline, Di(meth)acrylates of polyhydric alcohols having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), such as pyrene glycol di(meth)acrylate and bisphenol A di(meth)acrylate; alkyl di(meth)acrylates having 2 to 4 carbon atoms and having 2 to 50 additional moles of alkylene oxide groups, such as polyethylene glycol di(meth)acrylate having 2 to 50 additional moles of ethylene oxide, polypropylene glycol di(meth)acrylate having 2 to 50 additional moles of propylene oxide, and tripropylene glycol di(meth)acrylate; Acrylates; polyhydric alcohols having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), such as ethoxylated glycerin tri(meth)acrylate, propylene oxide-modified glycerol tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol monohydroxytri(meth)acrylate, trimethylolpropane triethoxytri(meth)acrylate, and trimethylolpropane tripropoxytri(meth)acrylate. tri(meth)acrylates of the above; tetra(meth)acrylates of polyhydric alcohols having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), such as pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate; penta(meth)acrylates of polyhydric alcohols having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), such as pentaerythritol penta(meth)acrylate and dipentaerythritol (monohydroxy)penta(meth)acrylate;Examples of the polyfunctional (meth)acrylate include, but are not limited to, hexa(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms, such as pentaerythritol hexa(meth)acrylate; 2-(2'-vinyloxyethoxyethyl)(meth)acrylate; and urethane(meth)acrylate. These polyfunctional monomers may be used alone or in combination of two or more.

[0053] As long as the monomers other than the monofunctional monomer have a predetermined biomass degree, the biomass degree of the polyfunctional monomer of the present disclosure (particularly the polyfunctional monomer as an acrylic monomer) may be 0%, but from the viewpoint of environmental impact, the biomass degree is preferably 1% or more, and more preferably 5% or more.

[0054] The content ratio of polyfunctional monomers (particularly polyfunctional monomers as acrylic monomers) in 100 parts by mass of the acrylic polymer of the present disclosure may be, for example, 0 parts by mass or more or 1 part by mass or more, and may be 10 parts by mass or less or 5 parts by mass or less (i.e., preferably 0 to 10 parts by mass, more preferably 1 to 5 parts by mass).

[0055] The acrylic polymer of the present disclosure may contain an ultraviolet absorbing monomer as a monomer component. Examples of the ultraviolet absorbing monomer include, but are not limited to, benzotriazole-based ultraviolet absorbing monomers and benzophenone-based ultraviolet absorbing monomers. These ultraviolet absorbing monomers may be used alone or in combination of two or more.

[0056] Examples of the benzotriazole-based ultraviolet absorbing monomer include 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-5-tert-butyl-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-5-tert-butyl-2H-benzotriazole, p) acryloylaminomethyl-5'-tert-octylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxypropylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyhexylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazo 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, 2-[2'-hydroxy-5'-tert-butyl-3'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, Examples of the benzotriazole-based ultraviolet absorbing monomer include, but are not limited to, 2-[2'-hydroxy-5'-(β-(meth)acryloyloxyethoxy)-3'-tert-butylphenyl]-5-cyano-2H-benzotriazole, 2-[2'-hydroxy-5'-(β-(meth)acryloyloxyethoxy)-3'-tert-butylphenyl]-4-tert-butyl-2H-benzotriazole, etc. These benzotriazole-based ultraviolet absorbing monomers may be used alone or in combination of two or more.

[0057] Examples of benzophenone-based ultraviolet absorbing monomers include, but are not limited to, 2-hydroxy-4-(meth)acryloyloxybenzophenone, 2-hydroxy-4-[2-hydroxy-3-(meth)acryloyloxy]propoxybenzophenone, 2-hydroxy-4-[2-(meth)acryloyloxy]ethoxybenzophenone, 2-hydroxy-4-[3-(meth)acryloyloxy-2-hydroxypropoxy]benzophenone, and 2-hydroxy-3-tert-butyl-4-[2-(meth)acryloyloxy]butoxybenzophenone. These benzophenone-based ultraviolet absorbing monomers may be used alone or in combination of two or more.

[0058] The acrylic resin of the present disclosure is preferably in the form of emulsion particles, and from the viewpoint of safety, is more preferably in the form of an aqueous dispersion containing acrylic resin particles (also referred to as resin particles). By having a certain biomass content of the present disclosure and being in the form of an aqueous dispersion, it is possible to obtain an ink with a low environmental impact.

[0059] The resin particles of the present disclosure may be formed of a single layer or multiple layers. When the resin particles of the present disclosure are formed in a single layer, they may have the composition described above for the acrylic polymer. When the resin particles of the present disclosure are formed in multiple layers, one or more selected from piperidine group-containing monomers, addition-polymerizable oxazolines, and hydroxyl group-containing (meth)acrylates may be included in the monomer components constituting any of the layers. However, from the viewpoint of further improving adhesion, it is preferable that they be included in the monomer components constituting at least the outermost layer. Therefore, it is preferable that the monomer components constituting the resin particles of the present disclosure contain at least one selected from piperidine group-containing monomers, addition-polymerizable oxazolines, and hydroxyl group-containing (meth)acrylates. When the emulsion particles are formed in multiple layers, it is preferable that the monomer components constituting at least the outermost layer contain at least one selected from piperidine group-containing monomers, addition-polymerizable oxazolines, and hydroxyl group-containing (meth)acrylates. The content of the piperidine group-containing monomers, addition-polymerizable oxazolines, and hydroxyl group-containing (meth)acrylates in the monomer components is preferably 0.1 to 30% by mass, more preferably 0.2 to 20% by mass, and even more preferably 0.5 to 10% by mass, respectively. The total content of the piperidine group-containing monomer, addition-polymerizable oxazoline, and hydroxyl group-containing (meth)acrylate in the monomer component is preferably 0.2 to 30% by mass, and more preferably 0.2 to 20% by mass.

[0060] When the resin particles of the present disclosure are formed of multiple layers, they preferably have 2 to 4 layers, and more preferably 2 or 3 layers. In emulsion particles having a multilayer resin layer structure, the inner layer refers to the innermost layer (core) of the emulsion particle, the outer layer refers to the other layers excluding the innermost layer (i.e., layers other than the innermost layer, including the outermost layer), and the outermost layer refers to the layer formed on the outermost side. When the resin particles of the present disclosure are formed in multiple layers, the content of the structural unit derived from a (meth)acrylate having a cyclic aliphatic group in 100 parts by mass of the monomer component forming the inner layer (innermost layer) may be 30 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and may be 95 parts by mass or less, preferably 90 parts by mass or less, and more preferably 85 parts by mass or less (i.e., 30 to 95 parts by mass is preferred, 35 to 95 parts by mass is more preferred, 40 to 90 parts by mass is even more preferred, and 45 to 85 parts by mass is particularly preferred).

[0061] When the resin particles of the present disclosure are formed in multiple layers, the content of structural units derived from a monomer other than a (meth)acrylate having a cyclic aliphatic group (hereinafter referred to as other monomer A) in 100 parts by mass of the monomer component forming the inner layer (innermost layer) may be 20 parts by mass or more, preferably 25 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, and may be 70 parts by mass or less, preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less.

[0062] When the resin particles of the present disclosure are formed in a plurality of layers, in 100 parts by mass of the monomer component forming the inner layer (innermost layer), other structural units derived from the monomer A include acid group-containing monomers (particularly (meth)acrylic acid, etc.), (meth)acrylates having a linear alkyl group or a branched alkyl group (particularly methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isostearyl (meth)acrylate, etc.), hydroxyl group-containing (meth)acrylates, Preferred are acrylates (particularly 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.), epoxy group-containing monomers (particularly glycidyl (meth)acrylate, etc.), styrene-based monomers (particularly styrene, etc.), and piperidine group-containing monomers (particularly 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, etc.).

[0063] When the resin particles of the present disclosure are formed in multiple layers, the content of the structural unit derived from a (meth)acrylate having a cyclic aliphatic group in 100 parts by mass of the monomer component forming the outer layer (a layer other than the innermost layer) may be 30 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and may be 95 parts by mass or less, preferably 90 parts by mass or less, and more preferably 85 parts by mass or less (i.e., 30 to 95 parts by mass is preferred, 35 to 90 parts by mass is more preferred, 40 to 90 parts by mass is even more preferred, and 45 to 85 parts by mass is particularly preferred).

[0064] When the resin particles of the present disclosure are formed in multiple layers, the content of structural units derived from a monomer other than a (meth)acrylate having a cyclic aliphatic group (hereinafter referred to as other monomer B) in 100 parts by mass of the monomer component forming the outer layer (a layer other than the innermost layer) may be 20 parts by mass or more, preferably 25 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, and may be 70 parts by mass or less, preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less (i.e., 20 to 70 parts by mass is preferred, 25 to 65 parts by mass is more preferred, 30 to 60 parts by mass is even more preferred, and 35 to 55 parts by mass is particularly preferred).

[0065] When the resin particles of the present disclosure are formed in a plurality of layers, in 100 parts by mass of the monomer component forming the outer layer (a layer other than the innermost layer), examples of the structural unit derived from other monomer B include an acid group-containing monomer (particularly (meth)acrylic acid, etc.), a (particularly meth)acrylate having a linear alkyl group or a branched alkyl group (particularly methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isostearyl (meth)acrylate, etc.), a hydroxyl group-containing (meth)acrylate, (meth)acrylates (particularly 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.), epoxy group-containing monomers (particularly glycidyl (meth)acrylate, etc.), styrene-based monomers (particularly styrene, etc.), and piperidine group-containing monomers (particularly 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, etc.) are preferred.

[0066] When the resin particles of the present disclosure are formed in multiple layers, the content of the structural unit derived from a (meth)acrylate having a cyclic aliphatic group in 100 parts by mass of the monomer component forming the outermost layer may be 30 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, and may be 95 parts by mass or less, preferably 90 parts by mass or less, and more preferably 85 parts by mass or less (i.e., 30 to 95 parts by mass is preferred, 35 to 95 parts by mass is more preferred, 40 to 90 parts by mass is even more preferred, and 45 to 85 parts by mass is particularly preferred). When the resin particles of the present disclosure are formed in multiple layers, the content of structural units derived from a monomer other than a (meth)acrylate having a cyclic aliphatic hydrocarbon group (hereinafter referred to as other monomer C) in 100 parts by mass of the monomer component forming the outermost layer may be 20 parts by mass or more, preferably 25 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, and may be 70 parts by mass or less, preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less (i.e., 20 to 70 parts by mass is preferred, 25 to 65 parts by mass is more preferred, 30 to 60 parts by mass is even more preferred, and 35 to 55 parts by mass is particularly preferred).

[0067] When the resin particles of the present disclosure are formed of a plurality of layers, in 100 parts by mass of the monomer component forming the outermost layer, examples of the structural units derived from other monomer C include acid group-containing monomers (e.g., (meth)acrylic acid), (meth)acrylates having a linear alkyl group or a branched alkyl group (particularly, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isostearyl (meth)acrylate, etc.), hydroxyl group-containing (meth)acrylates, Preferred are acrylates (particularly 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.), epoxy group-containing monomers (particularly glycidyl (meth)acrylate, etc.), styrene-based monomers (particularly styrene, etc.), and piperidine group-containing monomers (particularly 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, etc.).

[0068] When the resin particles of the present disclosure are formed of multiple layers, the mass ratio of the polymer layer constituting the inner layer (innermost layer) of the present disclosure to the polymer layer constituting the outer layer (layer other than the innermost layer) (polymer layer constituting the inner layer / polymer layer constituting the outer layer) is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 80 / 20, even more preferably 30 / 70 to 70 / 30, and even more preferably 40 / 60 to 60 / 40, from the viewpoint of improving flexibility, blocking resistance, adhesion to the substrate, and scratch resistance.

[0069] In the present disclosure, the mass ratio of the polymer layer constituting the inner layer (innermost layer) to the polymer layer constituting the outermost layer (polymer layer constituting the inner layer / polymer layer constituting the outermost layer) is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 80 / 20, even more preferably 30 / 70 to 70 / 30, and even more preferably 40 / 60 to 60 / 40, from the viewpoint of improving flexibility, blocking resistance, adhesion to the substrate, and scratch resistance.

[0070] <Physical properties of acrylic resin> The glass transition temperature of the acrylic resin of the present disclosure may be -30°C or higher or -10°C or higher, preferably 0°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher, from the viewpoint of improving blocking resistance, abrasion resistance, adhesion, and adhesive tape peelability. The glass transition temperature may be 90°C or lower, preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower (that is, the glass transition temperature may be -30 to 90°C, preferably -10 to 90°C, more preferably 0 to 80°C, even more preferably 5 to 70°C, and particularly preferably 10 to 60°C).

[0071] When the acrylic resin of the present disclosure is in the form of resin particles and is a single-layer emulsion particle, the glass transition temperature of the acrylic polymer constituting the acrylic resin is preferably within the above range. The glass transition temperature of the acrylic polymer can be adjusted by adjusting the type and amount of the monomer that forms the acrylic polymer.

[0072] When the acrylic resin of the present disclosure is in the form of resin particles and is formed in multiple layers, the glass transition temperature of the polymer constituting the inner layer (innermost layer) is -10°C or higher, preferably 0°C or higher, from the viewpoints of adhesion and scratch resistance, and the upper limit of the glass transition temperature is preferably 120°C or lower, more preferably 100°C or lower, from the viewpoints of adhesion and scratch resistance (i.e., -10 to 120°C is preferred, and 0 to 100°C is more preferred). The glass transition temperature of the polymer forming the inner layer (innermost layer) can be adjusted by adjusting the type and amount of the monomer forming the inner layer (innermost layer).

[0073] When the acrylic resin of the present disclosure is in the form of resin particles and is formed in multiple layers, the glass transition temperature of the polymer constituting the outer layer (a layer other than the innermost layer) is 0°C or higher, preferably 10°C or higher, from the viewpoints of adhesion, scratch resistance, and film-forming ability, and the upper limit of the glass transition temperature is preferably 100°C or lower, more preferably 90°C or lower, from the viewpoints of adhesion and scratch resistance (i.e., 0 to 100°C is preferred, and 10 to 90°C is more preferred). The glass transition temperature of the polymer constituting the outer layer (a layer other than the innermost layer) can be adjusted by adjusting the type and amount of the monomer that forms the outer layer (a layer other than the innermost layer).

[0074] When the acrylic resin of the present disclosure is in the form of resin particles and is formed in multiple layers, the glass transition temperature of the polymer constituting the outermost layer is 0°C or higher, preferably 10°C or higher, from the viewpoints of adhesion, scratch resistance, and film-forming ability, and the upper limit of the glass transition temperature is preferably 100°C or lower, more preferably 90°C or lower, from the viewpoints of adhesion and scratch resistance (i.e., 0 to 100°C is preferred, and 10 to 90°C is more preferred). The glass transition temperature of the polymer forming the outermost layer can be adjusted by adjusting the type and amount of the monomer forming the outermost layer.

[0075] The acrylic resin of the present disclosure does not need to have an acid value, but if it does have an acid value, the value may be 50 mgKOH / g or less, preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less, and particularly preferably 10 mgKOH / g or less. By having an acid value within the above range, a water-based ink with a viscosity suitable for use as an inkjet ink can be obtained, and improvements in adhesion, scratch resistance, blocking resistance, adhesive tape peelability, and ejection stability can be expected. When the acrylic resin of the present disclosure is in the form of resin particles and is formed into multiple layers, the polymer constituting the inner layer (innermost layer) does not need to have an acid value, but if it does have an acid value, the value may be 50 mgKOH / g or less, preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less, and particularly preferably 10 mgKOH / g or less. When the acid value of the polymer constituting the resin particle inner layer (innermost layer) is within the above range, an aqueous ink with a viscosity suitable for inkjet ink can be obtained, and effects of improving adhesion, scratch resistance, blocking resistance, adhesive tape peelability, and ejection stability can be expected.

[0076] When the acrylic resin of the present disclosure is in the form of resin particles and is formed of multiple layers, the polymer constituting the outer layer (a layer other than the innermost layer) may have an acid value of 0, but may have an acid value of 50 mgKOH / g or less, preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less, and particularly preferably 10 mgKOH / g or less. By having the acid value of the outer layer (a layer other than the innermost layer) of the resin particles within the above range, a water-based ink with a viscosity suitable for inkjet ink can be obtained, and improvements in adhesion, scratch resistance, blocking resistance, adhesive tape peelability, and ejection stability can be expected.

[0077] When the acrylic resin of the present disclosure is in the form of resin particles and is formed of multiple layers, the polymer constituting the outermost layer does not need to have an acid value, but if it does have an acid value, the value may be 50 mgKOH / g or less, preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less, and particularly preferably 10 mgKOH / g or less. When the acid value of the outermost layer of the resin particles is within the above range, an aqueous ink with a viscosity suitable for use as an inkjet ink can be obtained, and improvements in adhesion, scratch resistance, blocking resistance, adhesive tape peelability, and ejection stability can be expected.

[0078] The weight average molecular weight of the acrylic resin of the present disclosure is preferably 100,000 or more, more preferably 300,000 or more, even more preferably 400,000 or more, and even more preferably 500,000 or more, from the viewpoint of improving adhesion, film-forming properties, and leveling properties. The upper limit of the weight average molecular weight of the resin is not particularly limited when it has a crosslinked structure, since it is difficult to measure the weight average molecular weight. However, when it does not have a crosslinked structure, the upper limit is preferably 4,000,000 or less, from the viewpoint of obtaining an aqueous ink that is excellent overall in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. In the present invention, the weight-average molecular weight of the acrylic resin refers to the weight-average molecular weight (polystyrene equivalent) determined from a gel permeation chromatography chart prepared using a gel permeation chromatography equipped with an RI detector (Tosoh Corporation, product number: HLC-8120GPC, columns: TSKgel G-5000HXL and TSKgel GMHXL-L used in series, developing solvent: tetrahydrofuran (THF)) and a calibration curve prepared using standard polystyrenes F-450, A-5000, A-1000, and A-300, all of which are manufactured by Tosoh Corporation.

[0079] <Method of manufacturing acrylic resin> The acrylic resin of the present disclosure can be produced by any of the existing methods, such as bulk polymerization, suspension polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, etc. Among these, emulsion polymerization is preferred from the viewpoint of reducing the environmental load, and it is more preferred to use an aqueous medium such as water as the solvent from the viewpoint of safety.

[0080] In producing the acrylic resin of the present disclosure, examples of methods for emulsion polymerizing the monomer components include, but are not limited to, an aqueous medium containing a water-soluble organic solvent, such as a lower alcohol (e.g., methanol), and water, a method in which an emulsifier is dissolved in a medium such as water and the monomer components and a polymerization initiator are added dropwise under stirring, and a method in which the monomer components, which have been previously emulsified using an emulsifier and water, are added dropwise to water or an aqueous medium. The amount of medium may be appropriately determined taking into account the amount of nonvolatile matter contained in the resulting emulsion. The medium may be charged in advance into a reaction vessel or may be used as a pre-emulsion. If necessary, the medium may be used during emulsion polymerization of the monomer components to produce the emulsion.

[0081] When emulsion-polymerizing the monomer components, the emulsion polymerization may be carried out after mixing the monomer components, emulsifier, and medium, or after emulsifying the monomer components, emulsifier, and medium by stirring to prepare a pre-emulsion, or after mixing at least one of the monomer components, emulsifier, and medium with the remaining pre-emulsion, and then carrying out emulsion polymerization. The monomer components, emulsifier, and medium may each be added all at once, added in portions, or added dropwise continuously.

[0082] When an outer layer made of the outer layer polymer component is formed on the emulsion particles contained in the emulsion obtained above, the outer layer can be formed on the emulsion particles by emulsion polymerization of the monomer component in the emulsion in the same manner as described above. Furthermore, when a further outer layer is formed on the emulsion particles on which the outer layer (intermediate layer) has been formed, the monomer component can be emulsion polymerized in the emulsion in the same manner as described above to form a further outer layer made of another outer layer polymer component on the emulsion particles. In this way, emulsion particles having a multilayer structure (core-shell emulsion particles) can be prepared by the multistage emulsion polymerization method.

[0083] In preparing the core-shell emulsion particles, one or more emulsion polymerization stages may be carried out before the emulsion polymerization to form the inner layer composed of the inner layer polymer components, or one or more emulsion polymerization stages may be carried out between the emulsion polymerization to form the inner layer and the emulsion polymerization to form the intermediate layer. Also, one or more emulsion polymerization stages may be carried out between the emulsion polymerization to form the intermediate layer and the emulsion polymerization to form the outer layer. Furthermore, one or more emulsion polymerization stages may be carried out after the emulsion polymerization to form the outer layer. Examples of emulsifiers include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, and polymeric emulsifiers. These emulsifiers may be used alone or in combination of two or more.

[0084] The biomass degree of the emulsifier of the present disclosure is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40% or more, from the viewpoint of environmental impact.

[0085] Examples of anionic emulsifiers include alkyl sulfate salts such as ammonium dodecyl sulfate and sodium dodecyl sulfate; alkyl sulfonate salts such as ammonium dodecyl sulfonate, sodium dodecyl sulfonate, and sodium alkyl diphenyl ether disulfonate; alkyl aryl sulfonate salts such as ammonium dodecyl benzene sulfonate and sodium dodecyl naphthalene sulfonate; polyoxyethylene alkyl sulfonate salts; polyoxyethylene alkyl sulfate salts; polyoxyethylene alkyl aryl sulfate salts; dialkyl sulfosuccinate salts; aryl sulfonic acid-formalin condensates; Examples of the carboxylic acid salt include fatty acid salts such as ammonium laurate and sodium stearylate; sulfates having an allyl group or salts thereof such as bis(polyoxyethylene polycyclic phenyl ether) methacrylate sulfonate salts, propenyl-alkyl sulfosuccinate ester salts, (meth)acrylic acid polyoxyethylene sulfonate salts, (meth)acrylic acid polyoxyethylene phosphonate salts, and sulfonate salts of allyloxymethyl alkyloxy polyoxyethylene; sulfate salts of allyloxymethyl alkoxyethyl polyoxyethylene, and polyoxyalkylene alkenyl ether ammonium sulfate salts, but are not limited to these examples.

[0086] Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, condensates of polyethylene glycol and polypropylene glycol, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides, condensates of ethylene oxide and aliphatic amines, allyloxymethylalkoxyethylhydroxypolyoxyethylene, polyoxyalkylene alkenyl ethers, and the like, but are not limited to these examples.

[0087] Examples of cationic emulsifiers include alkyl ammonium salts such as dodecyl ammonium chloride, but the present invention is not limited to these examples. Examples of amphoteric emulsifiers include, but are not limited to, betaine ester emulsifiers. Examples of polymeric emulsifiers include poly(meth)acrylates such as sodium polyacrylate; polyvinyl alcohol; polyvinylpyrrolidone; polyhydroxyalkyl(meth)acrylates such as polyhydroxyethyl acrylate; and copolymers containing one or more of the monomers that make up these polymers as copolymerization components, but are not limited to these examples.

[0088] Furthermore, as the emulsifier, from the viewpoint of further improving water resistance and image uniformity, an emulsifier having a polymerizable group, i.e., a so-called reactive emulsifier, is preferred, and from the viewpoint of environmental protection, a non-nonylphenyl type emulsifier is preferred.

[0089] Examples of the reactive emulsifier include propenyl-alkyl sulfosuccinate salts, (meth)acrylic acid polyoxyethylene sulfonate salts, (meth)acrylic acid polyoxyethylene phosphonate salts (e.g., Sanyo Chemical Industries, Ltd., trade name: Eleminol RS-30, etc.), polyoxyethylene alkylpropenylphenyl ether sulfonate salts (e.g., Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10, etc.), sulfonate salts of allyloxymethyl alkyloxy polyoxyethylene (e.g., Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon KH-10, etc.), sulfonate salts of allyloxymethyl nonylphenoxyethyl hydroxy polyoxyethylene (e.g., ADEKA Corporation, trade name: Adeka Reasoap SE-10, etc.), allyloxymethyl alkoxyethyl hydroxy polyoxyethylene Examples of suitable hydroxypropyl methyl acrylates include, but are not limited to, methacrylate ester salts (e.g., ADEKA CORPORATION, trade names: ADEKA REASOAP SR-10, SR-20, SR-30, etc.), bis(polyoxyethylene polycyclic phenyl ether) methacrylated sulfonate salts (e.g., NIPPON NYUKAZAI CO., LTD., trade name: ANTOX MS-60, etc.), allyloxymethylalkoxyethylhydroxypolyoxyethylene (e.g., ADEKA CORPORATION, trade name: ADEKA REASOAP ER-10, ER-20, ER-30, etc.), polyoxyethylene alkylpropenylphenyl ether (e.g., Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon RN-20, etc.), and allyloxymethylnonylphenoxyethylhydroxypolyoxyethylene (e.g., ADEKA CORPORATION, trade name: ADEKA REASOAP NE-10, etc.).

[0090] The amount of emulsifier per 100 parts by mass of the monomer component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, and particularly preferably 3 parts by mass or more, from the viewpoint of improving polymerization stability, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, from the viewpoint of improving water resistance.

[0091] Examples of polymerization initiators include azo compounds such as azobisisobutyronitrile, 2,2-azobis(2-methylbutyronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-diaminopropane) hydrochloride, 4,4-azobis(4-cyanovaleric acid), and 2,2-azobis(2-methylpropionamidine); persulfates such as ammonium persulfate and potassium persulfate; and peroxides such as hydrogen peroxide, benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide, and ammonium peroxide, but the invention is not limited to these examples. These polymerization initiators may be used alone or in combination of two or more.

[0092] The amount of polymerization initiator per 100 parts by mass of the monomer component is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, from the viewpoint of increasing the polymerization rate and reducing the amount of remaining unreacted monomer component, and is preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, from the viewpoint of improving water resistance (i.e., 0.05 to 1 part by mass is preferred, and 0.1 to 0.5 parts by mass is more preferred).

[0093] The method for adding the polymerization initiator is not particularly limited. Examples of the addition method include batch addition, divided addition, continuous dropwise addition, etc. In order to hasten the completion of the polymerization reaction, a portion of the polymerization initiator may be added before or after the completion of the addition of the monomer components to the reaction system.

[0094] In order to promote the decomposition of the polymerization initiator, a suitable amount of a decomposer for the polymerization initiator, such as a reducing agent such as sodium hydrogen sulfite or a transition metal salt such as ferrous sulfate, may be added to the reaction system. A chain transfer agent can be used to adjust the weight-average molecular weight of the emulsion particles. Examples of chain transfer agents include, but are not limited to, 2-ethylhexyl thioglycolate, tert-dodecyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid, 2-mercaptoethanol, α-methylstyrene, and α-methylstyrene dimer. These chain transfer agents may be used alone or in combination of two or more. The amount of chain transfer agent per 100 parts by mass of the monomer component is preferably 0.01 to 10 parts by mass, from the viewpoint of appropriately adjusting the weight-average molecular weight of the emulsion particles.

[0095] If necessary, additives such as pH buffers, chelating agents, and film-forming aids may be added to the reaction system. The amount of additive varies depending on the type of additive and cannot be determined in general. Typically, the amount of additive per 100 parts by mass of the monomer component is preferably about 0.01 to 5 parts by mass, more preferably about 0.1 to 3 parts by mass. The atmosphere in which the monomer components are emulsion-polymerized is not particularly limited, but from the viewpoint of increasing the efficiency of the polymerization initiator, an inert gas such as nitrogen gas is preferred. The polymerization temperature when emulsion polymerizing the monomer components is not particularly limited, but is usually preferably 50 to 100° C., more preferably 60 to 95° C. The polymerization temperature may be constant or may be changed during the polymerization reaction.

[0096] The polymerization time for emulsion polymerization of the monomer components is not particularly limited and may be appropriately set depending on the progress of the polymerization reaction, but is usually about 2 to 9 hours. When the monomer components are emulsion-polymerized, some or all of the acidic groups in the resulting polymer component may be neutralized with a neutralizing agent. The neutralizing agent may be used after the monomer components are added in the final stage, for example, between the first and second polymerization stages, or at the end of the initial emulsion polymerization reaction. Examples of neutralizing agents include, but are not limited to, alkaline substances such as hydroxides of alkali metals or alkaline earth metals, such as sodium hydroxide; carbonates of alkali metals or alkaline earth metals, such as sodium bicarbonate and calcium carbonate; and organic amines, such as ammonia, monomethylamine, and dimethylaminoethanol. Among these neutralizing agents, volatile alkaline substances, such as ammonia, are preferred from the viewpoint of improving water resistance, and sodium bicarbonate is preferred from the viewpoint of improving the storage stability of emulsion particles. The neutralizing agent can be used, for example, as an aqueous solution.

[0097] Furthermore, when emulsion-polymerizing the monomer components, an appropriate amount of a silane coupling agent may be used to improve water resistance. Examples of the silane coupling agent include, but are not limited to, silane coupling agents having a polymerizable unsaturated bond such as a (meth)acryloyl group, a vinyl group, an allyl group, or a propenyl group. By emulsion-polymerizing the monomer components in the manner described above, an emulsion containing emulsion particles is obtained. When forming an outer layer on the emulsion particles obtained as described above, it is preferable to emulsion-polymerize the monomer components constituting the outer layer after the polymerization reaction rate during production of the emulsion particles has reached 90% or more, preferably 95% or more, from the viewpoint of forming a layer-separated structure within the emulsion particles.

[0098] After the inner layer of the emulsion particle is formed and before the outer layer is formed, a layer made of another polymer component may be formed, if necessary, within the scope of not impairing the object of the present invention. Therefore, when producing the emulsion particles contained in the emulsion for aqueous ink of the present disclosure, after the inner layer of the emulsion particle is formed and before the outer layer is formed, a layer made of another polymer component may be formed, if necessary, within the scope of not impairing the object of the present invention.

[0099] The monomer component used to form the outer layer may be the same as the monomer component used as the raw material for the inner layer of the emulsion particle, and the emulsion polymerization method and polymerization conditions for forming the outer layer may be the same as the method and polymerization conditions for producing the inner layer of the emulsion particle. In this manner, emulsion particles having an inner layer and an outer layer can be obtained. If necessary, a surface layer made of another polymer component may be further formed on the surface of the outer layer, as long as the object of the present invention is not impaired. After the inner layer of the emulsion particle is prepared as described above, the outer layer is formed on the inner layer, thereby obtaining an emulsion particle having an inner layer and an outer layer. The emulsion can be further crosslinked by adding a crosslinking agent. The crosslinking agent may be one that initiates a crosslinking reaction at room temperature or one that initiates a crosslinking reaction when heated. In the aqueous ink emulsion of the present disclosure, by adding a crosslinking agent to the emulsion particles, blocking resistance and adhesion can be further improved. Suitable crosslinking agents include, for example, oxazoline group-containing compounds, isocyanate group-containing compounds, and aminoplast resins. These crosslinking agents may be used alone or in combination of two or more. Among these crosslinking agents, oxazoline group-containing compounds are preferred from the viewpoint of improving the storage stability of the aqueous ink emulsion of the present disclosure.

[0100] <Aqueous dispersion containing acrylic resin particles> The content of the acrylic polymer in 100 parts by mass of the aqueous dispersion of the present disclosure may be 20 parts by mass or more, preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more, from the viewpoint of low viscosity and ejection stability, and may be 70 parts by mass or less, preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less (i.e., 20 to 70 parts by mass is preferred, 25 to 65 parts by mass is more preferred, 30 to 60 parts by mass is even more preferred, and 35 to 55 parts by mass is particularly preferred). The content of the acrylic polymer in 100 parts by mass of the nonvolatile content of the aqueous dispersion of the present disclosure may be 80 parts by mass or more, preferably 82 parts by mass or more, and more preferably 85 parts by mass or more, from the viewpoint of low viscosity and ejection stability, and may be 100 parts by mass or less, preferably 98 parts by mass or less, and more preferably 95 parts by mass or less (i.e., 80 to 100 parts by mass is preferred, 82 to 98 parts by mass is more preferred, and 85 to 95 parts by mass is even more preferred). The nonvolatile content of the aqueous dispersion of the present disclosure may be calculated as the mass of the total mass of the aqueous dispersion minus the mass of the volatile components contained in the resin and various additives, or may be calculated by weighing 1 g of the aqueous dispersion, drying it in a hot air dryer at 110°C for 1 hour, and using the resulting residue as the nonvolatile content, using the formula: [Nonvolatile content (mass%) in aqueous resin dispersion] = ([mass of residue] ÷ [1 g of aqueous resin dispersion]) × 100 It may be determined based on the following.

[0101] Furthermore, the aqueous dispersion of the present disclosure may contain an appropriate amount of additives such as surfactants, film-forming aids, ultraviolet absorbers, ultraviolet protection agents, fillers, leveling agents, dispersants, thickeners, wetting agents, plasticizers, stabilizers, antioxidants, and polymer waxes, as long as the object of the present invention is not impaired. The polymeric waxes of the present disclosure may include natural waxes and synthetic waxes.

[0102] Examples of natural waxes include petroleum waxes, vegetable waxes, and animal and vegetable waxes. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum. Examples of vegetable waxes include carnauba wax, candelilla wax, rice wax, and Japan wax. Examples of animal and vegetable waxes include lanolin and beeswax.

[0103] Examples of synthetic waxes include synthetic hydrocarbon waxes and modified waxes. Examples of synthetic hydrocarbon waxes include polyolefin waxes, (meth)acrylic waxes, and Fischer-Tropsch waxes. Examples of modified waxes include paraffin wax derivatives, montan wax derivatives, and microcrystalline wax derivatives. From the viewpoint of improving adhesion and scratch resistance, polyolefin waxes and (meth)acrylic waxes are preferred.

[0104] The (meth)acrylic wax is not particularly limited, and may be, for example, one produced using a monomer having an alkyl group having 10 or more carbon atoms. Examples of (meth)acrylic monomers having an alkyl group having 10 or more carbon atoms include lauryl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, or polymers produced from derivatives thereof.

[0105] Commercially available (meth)acrylic waxes can also be used, and preferred commercial products include ST100 and ST200 manufactured by Nippon Shokubai Co., Ltd.

[0106] The polyolefin wax is not particularly limited, and examples thereof include waxes produced from olefins such as ethylene, propylene, butylene, or derivatives thereof, and copolymers thereof, specifically polyethylene wax, polypropylene wax, polybutylene wax, copolymer waxes made from ethylene and a monomer having a carboxylic acid group such as methacrylic acid or acrylic acid, oxidized polyethylene wax, etc. Among these, from the viewpoint of improving adhesion and scratch resistance, polyethylene wax, polypropylene wax, copolymer waxes made from ethylene and a monomer having a carboxylic acid group such as methacrylic acid or acrylic acid, and oxidized polyethylene wax are preferred.

[0107] The oxidized polyethylene wax of the present disclosure is obtained by oxidizing polyethylene wax and has a skeleton derived from polyethylene (polyethylene skeleton). The polyethylene skeleton mainly has structural units derived from ethylene. The polyethylene skeleton may be a homopolyethylene (ethylene homopolymer) skeleton, a block polyethylene (block copolymer of ethylene and other olefin) skeleton, or a random polyethylene (random copolymer of ethylene and other olefin) skeleton. Examples of the other olefin include alkenes such as propylene, isobutylene, 1-butene, 1-pentene, and 1-hexene. These components may be linear or branched. The number of carbon atoms of the other olefin component is, for example, 2 to 6.

[0108] The content of ethylene components in the polyethylene skeleton (content of structural units derived from ethylene) is, for example, 60 mol% or more, and may be 70 mol% or more. When the polyethylene skeleton is a block polyethylene skeleton or a random polyethylene skeleton, the content of ethylene components in the polyethylene skeleton (content of structural units derived from ethylene) is, for example, 95 mol% or less, and may be 90 mol% or less (i.e., the content is preferably 60 to 95 mol%, more preferably 70 to 90 mol%).

[0109] The oxidized polyethylene wax preferably contains high-density oxidized polyethylene wax, from the viewpoint of obtaining better adhesion and scratch resistance.

[0110] Commercially available oxidized polyethylene waxes can also be used, and preferred commercial products include AQUACER 497, AQUACER 515, AQUACER 4531, and AQUACER 1547 manufactured by BYK.

[0111] The polymer waxes can be used singly or in combination of two or more.

[0112] The polymer wax of the present disclosure is preferably in a state in which solid wax particles are dissolved or dispersed in a solvent, more preferably in a state in which the solid wax particles are dispersed in a solvent in an emulsion state. The solvent is preferably an aqueous medium, more preferably the same aqueous medium as that used in the aqueous ink composition.

[0113] The content (based on solid content) of the polymer wax of the present disclosure is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 3 to 20 parts by mass, relative to 100 parts by mass of the acrylic resin, from the viewpoint of improving adhesion, scratch resistance, blocking resistance, and adhesive tape peelability.

[0114] The biomass degree of the various additives used in the aqueous dispersion of the present disclosure is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40% or more, from the viewpoint of environmental load.

[0115] The minimum film-forming temperature of the aqueous dispersion of the present disclosure is preferably 100° C. or lower, more preferably 90° C. or lower, and even more preferably 70° C. or lower, from the viewpoint of improving scratch resistance, adhesion, and adhesive tape peeling resistance. The lower limit of the minimum film-forming temperature of the aqueous dispersion of the present disclosure is preferably 0° C. or higher, more preferably 10° C. or higher, and even more preferably 30° C. or higher, from the viewpoint of further improving water resistance, weather resistance, scratch resistance, adhesion, adhesive tape peeling resistance, and blocking resistance (i.e., the minimum film-forming temperature is preferably 0 to 100° C., more preferably 10 to 90° C., and even more preferably 30 to 70° C.).

[0116] In this specification, the minimum film-forming temperature of an aqueous dispersion means the minimum temperature at which a crack-free, uniform film is formed when the aqueous dispersion is dried, and is measured in accordance with JIS K6828-2:2003.

[0117] The acrylic resin in the aqueous dispersion is preferably present as emulsion particles. The average particle size of the acrylic resin particles is preferably 50 nm or more, more preferably 100 nm or more, from the viewpoint of improving the mechanical stability of the particles themselves. The upper limit of the average particle size is preferably 300 nm or less, more preferably 200 nm or less, from the viewpoint of improving scratch resistance, adhesion, etc., and further improving water resistance, weather resistance, etc. (i.e., the average particle size is preferably 50 to 300 nm, more preferably 100 to 200 nm).

[0118] In this specification, the average particle size of the acrylic resin particles in the aqueous dispersion is a value (hydrodynamic diameter) determined by determining an autocorrelation function by photon correlation spectroscopy and performing cumulant analysis using a multi-analyte nanoparticle size measurement system (manufactured by Otsuka Electronics Co., Ltd., product name: nanoSAQLA), which is a particle size measurement device that uses dynamic light scattering.

[0119] <Application> The acrylic resin or aqueous dispersion containing the acrylic resin of the present disclosure can be suitably used in inks, and is particularly preferably used as an aqueous ink containing a water-based solvent. When used in a white ink, the content of the acrylic resin in 100 parts by mass of the aqueous ink of the present disclosure may be 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and may be 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less (i.e., 1 to 50 parts by mass is preferred, 3 to 40 parts by mass is more preferred, 5 to 30 parts is even more preferred, and 5 to 20 parts by mass is particularly preferred). On the other hand, when used in a color ink other than a white ink, from the viewpoint of ejection stability and storage stability, the content may be 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and may be 40 parts by mass or less, preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less (i.e., 1 to 40 parts by mass is preferred, 1 to 30 parts by mass is more preferred, 3 to 25 parts by mass is even more preferred, and 5 to 20 parts by mass is particularly preferred). The aqueous ink of the present disclosure contains a colorant. Examples of the hues of the colorant include achromatic colors such as white, black, and gray, and chromatic colors such as yellow, magenta, cyan, blue, red, orange, and green, but the aqueous ink of the present disclosure is not limited to these examples.

[0120] Examples of colorants in the present disclosure include pigments and dyes. Among these, pigments are preferred because of their excellent weather resistance. When using a pigment, the pigment may be used in the form of a pigment dispersion such as a paste. Examples of pigments include organic pigments and inorganic pigments, which may be used alone or in combination. The colorant used in the aqueous ink of the present disclosure is preferably any one colorant selected from white pigments, yellow, magenta, cyan, black, red, blue, and green.

[0121] The white pigment is not particularly limited, and known inorganic white pigments can be used. Examples include alkaline earth metal sulfates or carbonates; silicas such as finely powdered silicic acid and synthetic silicates; calcium silicate, alumina, alumina hydrate, titanium oxide, zinc oxide, talc, clay, and the like. The inorganic white pigments may also be surface-treated by various surface treatment methods. Surface-treated titanium oxide is preferred because it exhibits relatively good dispersibility in aqueous media. For example, to avoid the effects of photocatalysis, titanium oxide surface-treated with an inorganic substance is preferred, and titanium oxide surface-treated with silica and alumina is preferred. Furthermore, titanium oxide surface-treated with silica and alumina and then further surface-treated with a silane coupling agent can also be used, and this is even more preferred. In the titanium oxide surface-treated with silica and alumina, known rutile or anatase titanium dioxide can be used, with rutile titanium dioxide being more preferred.

[0122] The average particle size of the titanium oxide is preferably 100 to 500 nm, and more preferably 150 to 400 nm. If the average particle size is 100 nm or less, non-sedimentation and dispersion stability in an aqueous medium are more easily achieved, but the whiteness and hiding power are inferior, potentially reducing the practical utility of the original white ink. On the other hand, if the average particle size is 500 nm or more, there are no problems with the whiteness and hiding power, but the ejection stability tends to be insufficient. From a practical perspective, a particle size of 200 to 300 nm is even more preferable. The average particle size of titanium oxide used as a raw material is determined by averaging the particle sizes of 20 particles measured using an electron microscope. In the present invention, the average particle size of titanium oxide contained in the aqueous dispersion or the aqueous ink using the aqueous dispersion is not particularly limited, but can be measured by a dynamic light scattering method, a laser diffraction / scattering method, a Coulter counter, a microscope, or the like. More specifically, the average particle diameter is preferably the average particle diameter (hydrodynamic diameter) obtained by determining an autocorrelation function by photon correlation analysis using a multi-analyte nanoparticle diameter measurement system (manufactured by Otsuka Electronics Co., Ltd., product name: nanoSAQLA), which is a particle diameter measurement device using dynamic light scattering.

[0123] Yellow organic pigments include CI Pigment Yellow 1 (Hansa Yellow G), 2, 3 (Hansa Yellow 10G), 4, 5 (Hansa Yellow 5G), 6, 7, 10, 11, 12 (Disazo Yellow AAA), 13, 14, 16, 17, 24 (Flavanthrone Yellow), 55 (Disazo Yellow AAPT), 61, 61:1, 65, 73, 74 (Fast Yellow 5GX), 75, 81, 83 (Disazo Yellow HR), 93 (Condensed Azo Yellow 3G), 94 (Condensed Azo Yellow 6G), 95 (Condensed Azo Yellow GR), 97 (Fast Yellow FGL), 98, 99 (Anthraquinone), 100, 108 (Anthrapyrimidine Yellow), and 109 (Isoindoline). Examples of suitable benzoindolinone yellows include 110 (Isoindolinone Yellow 3RLT), 113, 117, 120 (Benzimidazolone Yellow H2G), 123 (Anthraquinone Yellow), 124, 128 (Condensed Azo Yellow 8G), 129, 133, 138 (Quinophthalone Yellow), 139 (Isoindolinone Yellow), 147, 151 (Benzimidazolone Yellow H4G), 153 (Nickel Nitroso Yellow), 154 (Benzimidazolone Yellow H3G), 155, 156 (Benzimidazolone Yellow HLR), 167, 168, 172, 173 (Isoindolinone Yellow 6GL), and 180 (Benzimidazolone Yellow). Organic pigments for magenta water-based inks include CI Pigment Red 1 (Para Red), 2, 3 (Toluidine Red), 4, 5 (lTR Red), 6,7,8,9,10,11,12,14,15,16,17,18,19,21,22,23,30,31,32,37,38 (Pyrazolone Red B), 40,41,42,88 (Thioindigo Bordeaux), 112 (Naphthol Red FGR), 114 (Brilliant Carmine BS), 122 (Dimethylquinacridone), 123 (Perylene Vermilion), 144,146,149 (Perylene Scar Red), 150,166,168 (Anthanthrone Orange), 170 (Naphthol Red F3RK), 171 (Benzimidazolone Maroon HFM), 175 (Benzimidazolone Red HFT), 176 (Benzimidazolone Carmine Examples of suitable pigments include CI Pigment Violet 19 (Quinacridone), CI Pigment Violet 23 (Dioxazine Violet), CI Pigment Violet 31 (Quinacridone), CI Pigment Violet 24 (Dioxazine Violet), CI Pigment Violet 32 (Quinacridone), CI Pigment Violet 33 (Dioxazine Violet), CI Pigment Violet 34 (Dioxazine Violet), CI Pigment Violet 35 (Dioxazine Violet), CI Pigment Violet 36 (Quinacridone), CI Pigment Violet 37 (Dioxazine Violet), CI Pigment Violet 38 (Dioxazine Violet), CI Pigment Violet 40 (Dioxazine Violet), CI Pigment Violet 41 (Dioxazine Violet), CI Pigment Violet 42 (Dioxazine Violet), CI Pigment Violet 43 (Dioxazine Violet), CI Pigment Violet 44 (Dioxazine Violet), CI Pigment Violet 45 (Naphthol Red), CI Pigment Violet 46 (Quinacridone), CI Pigment Violet 47 (Dioxazine Violet), CI Pigment Violet 48 (Dioxazine Violet), CI Pigment Violet 49 (Dioxazine Violet), CI Pigment Violet 50 (Dioxazine Violet), CI Pigment Violet 51 (Dioxazine Violet), CI Pigment Violet 52 (Dioxazine Violet), CI Pigment Violet 53 (Dioxazine Violet), CI Pigment Violet 54 (Dioxazine Violet), CI Pigment Violet 55 (Dioxazine Viole

[0124] Examples of organic pigments for cyan include CI Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, and 15:6 (all of which are phthalocyanine blues), 16 (metal-free phthalocyanine blue), 17:1, and 18 (alkali blue toner), as well as 19, 21, 22, 25, 56, and 60 (threne blue), 64 (dichloroindanthrone blue), 65 (violanthrone), and 66 (indigo). As the black organic pigment, a black organic pigment such as aniline black (CI Pigment Black 1) can be used.

[0125] Organic pigments used in colored water-based inks other than white pigment, yellow, cyan, or magenta water-based inks include CI Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16 (Balkan Orange), 24, 31 (Condensed Azo Orange 4R), 34, 36 (Benzimidazolone Orange HL), 38, 40 (Pyranthrone Orange), 42 (Isoindolinone Orange RLT), 43, 51, 60 (Benzimidazolone-based insoluble monoazo pigment), 62 (Benzimidazolone-based insoluble monoazo pigment), 63 (Benzimidazolone-based insoluble monoazo pigment), 64 (Benzimidazolone-based insoluble monoazo pigment), 65 (Benzimidazolone-based insoluble monoazo pigment), 66 (Benzimidazolone-based insoluble monoazo pigment), 67 (Benzimidazolone-based insoluble monoazo pigment), 68 (Benzimidazolone-based insoluble monoazo pigment), 69 ...70 (Benzimidazolone-based insoluble monoazo pigment), 71 (Benzimidazolone-based insoluble monoazo pigment), 72 (Benzimidazolone-based insoluble monoazo pigment), 73 (Benzimidazolone-based insoluble monoazo pigment), 74 (Benzimidazolone-based insoluble monoazo pigment), 75 (Benzimidazolone-based insoluble monoazo pigment), 76 (Benzimidazolone-based insoluble monoazo pigment), 77 (Benz Examples include CI Pigment Green 7 (Phthalocyanine Green), 10 (Green Gold), 36 (Chlorobrominated Phthalocyanine Green), 37, 47 (Violanthrone Green); and CI Pigment Brown 1, 2, 3, 5, 23 (Condensed Azo Brown 5R), 25 (Benzimidazolone Brown HFR), 26 (Perylene Bordeaux), and 32 (Benzimidazolone Brown HFL). The amount of colorant per 100 parts by mass of the nonvolatile content of the resin emulsion for aqueous ink used in the aqueous ink of the present disclosure is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, from the viewpoint of sufficiently coloring the print or image formed with the aqueous ink, and is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, from the viewpoint of forming a uniform coating film (i.e., 30 to 300 parts by mass is preferred, and 50 to 200 parts by mass is more preferred).

[0126] When a white pigment is used, the amount of white pigment per 100 parts by mass of the non-volatile content of the resin emulsion for aqueous ink is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, from the viewpoint of sufficiently coloring the print or image formed with the aqueous ink and improving color development, and is preferably 500 parts by mass or less, more preferably 400 parts by mass or less, from the viewpoint of forming a uniform coating film and / or improving gloss (i.e., 50 to 500 parts by mass is preferred, and 60 to 400 parts by mass is more preferred).

[0127] From the viewpoints of ink viscosity in the aqueous ink, control of wetting and spreading on the recording medium to be printed, improvement of image quality, and ejection stability, the aqueous ink may contain water as well as a water-soluble organic solvent.

[0128] Examples of organic solvents include glycols such as propylene glycol, 1,3-propanediol, glycerin, dipropylene glycol, tripropylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol; ethers of monoethylene glycol such as monoethylene glycol monomethyl ether, monoethylene glycol monoethyl ether, monoethylene glycol monopropyl ether, monoethylene glycol monoisopropyl ether, monoethylene glycol monobutyl ether, and monoethylene glycol monoisobutyl ether; ethers of monopropylene glycol such as monopropylene glycol monomethyl ether, monopropylene glycol monoethyl ether, monopropylene glycol monopropyl ether, monopropylene glycol monoisopropyl ether, monopropylene glycol monobutyl ether, and monopropylene glycol monoisobutyl ether; and diethylene glycol. ethers of polyethylene glycol, such as monomethyl ethers of polyethylene glycol (number of moles of EO added=2 to 10, preferably 2 to 4) such as diethylene glycol monomethyl ether, monoethyl ethers of polyethylene glycol (number of moles of EO added=2 to 10, preferably 2 to 4) such as diethylene glycol monoethyl ether, monopropyl ethers of polyethylene glycol (number of moles of EO added=2 to 10, preferably 2 to 4) such as diethylene glycol monopropyl ether, monoisopropyl ethers of polyethylene glycol (number of moles of EO added=2 to 10, preferably 2 to 4) such as diethylene glycol monoisopropyl ether, monobutyl ethers of polyethylene glycol (number of moles of EO added=2 to 10, preferably 2 to 4) such as diethylene glycol monobutyl ether, and monoisobutyl ethers of polyethylene glycol (number of moles of EO added=2 to 10, preferably 2 to 4) such as diethylene glycol monoisobutyl ether;Examples of polypropylene glycol ethers include monomethyl ether of polypropylene glycol (number of moles of EO added = 2 to 10, preferably 2 to 4), monoethyl ether of polypropylene glycol (number of moles of EO added = 2 to 10, preferably 2 to 4), monopropyl ether of polypropylene glycol (number of moles of EO added = 2 to 10, preferably 2 to 4), monoisopropyl ether of polypropylene glycol (number of moles of EO added = 2 to 10, preferably 2 to 4), monobutyl ether of polypropylene glycol (number of moles of EO added = 2 to 10, preferably 2 to 4), and monoisobutyl ether of polypropylene glycol (number of moles of EO added = 2 to 10, preferably 2 to 4). Among these, propylene glycol, diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, tripropylene glycol monomethyl ether, monoethylene glycol monoisopropyl ether, and monopropylene glycol monopropyl ether are preferred. These organic solvents may be used alone or in combination of two or more kinds.

[0129] The amount of the water-soluble organic solvent cannot be determined in general terms because it differs depending on the type and amount of colorant contained in the aqueous ink. Therefore, it is preferable to determine the amount appropriately depending on the type and amount of colorant contained in the aqueous ink.

[0130] For example, if the colorant contains a white pigment, the amount of organic solvent per 100 parts by mass of the aqueous ink may be 5 parts by mass or more, preferably 8 parts by mass or more, and more preferably 10 parts by mass or more, from the perspective of controlling the wetting and spreading of the ink onto the recording medium to be printed and improving image quality, and may be 50 parts by mass or less, preferably 45 parts by mass or less, and more preferably 40 parts by mass or less (i.e., 5 to 50 parts by mass is preferred, more preferably 8 to 45 parts by mass, and even more preferably 10 to 40 parts by mass).

[0131] The aqueous ink of the present disclosure contains the resin emulsion for aqueous ink and a colorant, but may also contain other resins such as resin emulsions other than the resin emulsion for aqueous ink, water-soluble resins, water-dispersible resins, etc., as long as the object of the present invention is not impaired. Furthermore, the aqueous ink of the present invention may also contain appropriate amounts of additives such as surfactants, film-forming aids, UV absorbers, UV inhibitors, fillers, leveling agents, dispersants, thickeners, wetting agents, plasticizers, stabilizers, and antioxidants, as long as the object of the present invention is not impaired.

[0132] From the viewpoints of water resistance, weather resistance, and environmental impact, the solids content of the aqueous ink of the present disclosure has a biomass ratio of 3% or more, preferably 5% or more, and more preferably 10% or more. The upper limit of the biomass ratio is not particularly limited, but may be, for example, 50% or less, or 30% or less. That is, the biomass ratio of the solids content is preferably 3 to 50%, more preferably 5 to 50%, and even more preferably 10 to 30%.

[0133] The aqueous ink of the present disclosure obtained as described above has excellent adhesion and scratch resistance, and can therefore be suitably used, for example, as an aqueous inkjet ink, an ink for flexographic printing, an ink for offset printing, an ink for lithographic printing, an ink for gravure printing, or an ink for screen printing, and can be particularly suitably used as an aqueous inkjet ink.

[0134] The ink composition or aqueous ink of the present disclosure can be applied to a printing substrate to produce a laminate. For example, the aqueous ink can be ejected onto the printing substrate in a predetermined pattern using an inkjet recording device or the like to form a print or image having a predetermined pattern.

[0135] Examples of printing substrates include paper, paper laminated with a resin film such as polyethylene, polypropylene, or polystyrene (coated paper, etc.), metal plates such as aluminum, zinc, or copper, resin films such as cellulose, polyethylene terephthalate, polystyrene, olefin resin, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, nylon, and acrylic resin, paper with a metal coating, and resin films with a metal coating. Resin films are preferred as printing substrates for printing with the aqueous ink of the present disclosure, and polyethylene terephthalate and olefin resins are particularly preferred. Examples of olefin resins include polyethylene and polypropylene, and the application to polypropylene, such as biaxially oriented polypropylene film (OPP) and non-oriented polypropylene film (CPP), is particularly preferred.

[0136] The aqueous ink of the present disclosure is preferably formed on a resin film, and in this embodiment, the resin film is a laminate having a printed layer formed from the aqueous ink. The laminate of the present disclosure may or may not have a primer layer between the resin film and the printing layer, but it is preferable that it does not have one from the viewpoint of productivity, and it is preferable that the printing layer is formed directly on the resin film. The laminate of the present disclosure is formed by laminating the resin film and the printing layer in this order, and may or may not have a protective film (laminate layer) on the printing layer, but it is preferable that it does not have one from the viewpoint of productivity, and by using the aqueous ink of the present disclosure, it is expected that a laminate having excellent adhesion to the substrate and good scratch resistance can be obtained even without a primer layer or a protective film (laminate layer). The laminate of the present disclosure can be suitably used for various printed materials.

[0137] This application claims the benefit of priority based on Japanese Patent Application No. 2021-120836, filed on July 21, 2021. The entire contents of the specification of Japanese Patent Application No. 2021-120836, filed on July 21, 2021, are incorporated herein by reference. [Example]

[0138] The present invention will now be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass."

[0139] <Glass transition temperature of polymer component> The glass transition temperature (Tg) of a polymer component is calculated using the glass transition temperature of a homopolymer of a monomer used in the monomer component constituting the polymer component, using the formula: 1 / Tg=Σ(Wm / Tgm) / 100 (wherein Wm represents the content (mass%) of monomer m in the monomer components constituting the polymer component, and Tgm represents the glass transition temperature (absolute temperature: K) of a homopolymer of monomer m.) The value was calculated based on the Fox equation:

[0140] <Acid value derived from carboxyl groups of resin emulsion particles> The acid value derived from the carboxyl groups of the resin emulsion particles means the number of milligrams of potassium hydroxide required to neutralize the carboxyl groups present in 1 g of the monomer component used to produce the particles.

[0141] <Non-volatile content measurement> 1 g of the resin emulsion was weighed and dried in a hot air dryer at 110°C for 1 hour, and the resulting residue was calculated as the nonvolatile content using the following formula. [Non-volatile content in resin emulsion (mass%)] = ([mass of residue] ÷ [1g of resin emulsion]) × 100

[0142] <Minimum film forming temperature> The minimum film-forming temperature of the resin emulsion was measured in accordance with JIS K6828-2:2003.

[0143] <Average particle size> The measurement temperature was 25±0.5°C, and a multi-analyte nanoparticle size measurement system (Otsuka Electronics Co., Ltd., product name: nanoSAQLA), a particle size measurement device using dynamic light scattering, was used to determine the autocorrelation function using the photon correlation method, and the average particle size (hydrodynamic diameter) was determined by cumulant analysis.

[0144] The abbreviations in each table have the following meanings: IBOA: Isobornyl acrylate EA: Ethyl acrylate CHMA: Cyclohexyl methacrylate St: styrene 2EHA: 2-ethylhexyl acrylate AA: acrylic acid HEMA: Hydroxyethyl methacrylate LA-87: 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine LA-82: 4-Methacryloyloxy-1,2,2,6,6-pentamethylpiperidine BYK-190: BYK Japan, dispersant (acid value 10 mg KOH / g) PG: ADEKA, propylene glycol CR-95: Titanium dioxide (rutile type) manufactured by Ishihara Sangyo Kaisha ST-200: Nippon Shokubai Co., Ltd. (meth)acrylic wax emulsion BDG: Diethylene glycol monobutyl ether, manufactured by Nippon Nyukazai Co., Ltd. KF-6011: PEG-11 methyl ether dimethicone (polyether-modified silicone surfactant), manufactured by Shin-Etsu Chemical Co., Ltd. PET: Futamura Chemical Co., Ltd., product name: Taiko Polyester Film FE2001 OPP: Manufactured by Futamura Chemical Co., Ltd., Product name: FOR-AQ

[0145] <Resin emulsion> <Core-shell emulsion> [Manufacturing Example 1] A flask equipped with a dropping funnel, stirrer, nitrogen gas inlet, thermometer, and reflux condenser was charged with 520 parts of deionized water. A first-stage pre-emulsion was prepared in the dropping funnel. The pre-emulsion consisted of 163 parts of deionized water, 80 parts of a 25% aqueous solution of emulsifier (ADEKA Corporation, trade name: ADEKA REASORB SR-10), 322 parts of isobornyl acrylate (IBOA) (biomass content: 73%), 103 parts of 2-ethylhexyl acrylate (2EHA), and 75 parts of 2-hydroxyethyl methacrylate (HEMA). 74 parts of this pre-emulsion, equivalent to 5% of the total amount of all monomer components, was added to the flask. The temperature was raised to 70°C while slowly blowing in nitrogen gas. 30 parts of a 5% aqueous solution of ammonium persulfate was added to initiate polymerization. The remaining pre-emulsion was then added dropwise to the flask over 120 minutes. After the dropwise addition was completed, the contents of the flask were maintained at 70°C for 60 minutes, and then a second-stage pre-emulsion consisting of 163 parts of deionized water, 80 parts of a 25% aqueous solution of an emulsifier (manufactured by ADEKA Corporation, trade name: ADEKA REASORB SR-10), 310 parts of isobornyl acrylate (IBOA) (biomass content: 73%), 105 parts of 2-ethylhexyl acrylate (2EHA), 75 parts of 2-hydroxyethyl methacrylate (HEMA), and 10 parts of 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine (manufactured by ADEKA Corporation, trade name: Adeka STAB LA-82), and 30 parts of a 5% aqueous solution of ammonium persulfate were uniformly added dropwise to the flask over a period of 120 minutes. After the dropwise addition was completed, the contents of the flask were maintained at 70°C for 60 minutes, and the pH was adjusted to 8 by adding 25% aqueous ammonia to terminate the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to prepare a resin emulsion. The nonvolatile content of this resin emulsion was 50%, the acid value derived from the carboxyl groups of the resin emulsion particles was 0 mgKOH / g, and the glass transition temperatures of the inner and outer layer resins constituting the particles (resin emulsion particles) contained in the resin emulsion were 38°C and 38°C, respectively. The minimum film-growth temperature was 50°C, the average particle size was 150 nm, and the biomass content of the nonvolatile content was 46%.

[0146] [Manufacturing Example 5] A polymer was prepared in the same manner as in Production Example 1, except that in Production Example 5, the monomer components shown in Table 1 were used for polymerization, thereby obtaining a resin emulsion of Production Example 5. The properties of the obtained resin emulsion are shown in Table 1.

[0147] <Single emulsion> [Manufacturing Example 2] Into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer and a reflux condenser, 536 parts of deionized water was placed. A pre-emulsion for the first stage of addition was prepared in a dropping funnel, consisting of 326 parts of deionized water, 160 parts of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Corporation, trade name: ADEKA REASORB SR-10], 632 parts of isobornyl acrylate (IBOA) (biomass content: 73%), 208 parts of 2-ethylhexyl acrylate (2EHA), 150 parts of 2-hydroxyethyl methacrylate (HEMA), and 10 parts of 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Corporation, trade name: Adeka STAB LA-87]. 74 parts of this pre-emulsion, corresponding to 5% of the total amount of all monomer components, was added to the flask, and the temperature was raised to 70°C while slowly blowing in nitrogen gas. 30 parts of a 5% aqueous solution of ammonium persulfate was added to initiate polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 30 parts of a 5% aqueous solution of ammonium persulfate were added dropwise uniformly into the flask over 180 minutes. After the dropwise addition was completed, the contents of the flask were maintained at 70°C for 60 minutes, and the pH was adjusted to 8 by adding 25% aqueous ammonia to terminate the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to prepare a resin emulsion. The nonvolatile content of this resin emulsion was 50%, the acid value derived from the carboxyl groups of the resin emulsion particles was 0 mg KOH / g, and the glass transition temperature of the resin constituting the particles contained in the resin emulsion (resin emulsion particles) was 38°C. The minimum film-forming temperature was 40°C, the average particle size was 150 nm, and the biomass content of the nonvolatile content was 46%.

[0148] [Manufacturing Examples 3 and 4] In Production Examples 3 and 4, polymers were prepared in the same manner as in Production Example 2, except that the monomer components shown in Table 1 were used for polymerization, to obtain resin emulsions of Production Examples 3 and 4. The properties of the obtained resin emulsions are shown in Table 1.

[0149] [Manufacturing Example 6-9] In Production Examples 6-9, polymers were prepared in the same manner as in Production Example 2, except that the monomer components shown in Table 2 were used for polymerization, to obtain resin emulsions of Production Examples 6-9. The properties of the obtained resin emulsions are shown in Table 2.

[0150] [Table 1] [Table 2]

[0151] The biomass degrees of the various biomass monomers shown in Tables 1 and 2 are as follows: IBOA: Isobornyl acrylate, biomass content 73% EA: Ethyl acrylate, biomass content 46%

[0152] [Manufacturing Example 10] A resin solution was prepared in the same manner as in Example 1 of JP 2019-172977 A. That is, a plant-derived dimer acid (dimer purity 98%) / plant-derived succinic acid = 90 / 10 (molar ratio) was used as the polyfunctional carboxylic acid component, and a plant-derived 1,3-propanediol was used as the polyfunctional alcohol component. These components were then polymerized in appropriate amounts to achieve the target molecular weight, yielding a polyester diol PE1 made of 100% plant-derived components with a hydroxyl value of 37.3 mg KOH / g, an acid value of 0.3 mg KOH / g, and a number average molecular weight of 3,000. Next, 500 parts of the polyester diol PE1 obtained above and 66.4 parts of isophorone diisocyanate, an organic diisocyanate, were charged into a reaction vessel and reacted for 5 hours at 100°C under a nitrogen stream to obtain a urethane prepolymer with an NCO group content of 1.87%. The obtained urethane prepolymer was dissolved in 188.8 parts of ethyl acetate, an organic solvent for dilution, to obtain a urethane prepolymer solution with a nonvolatile content of 75%. Next, a mixture (diamine solution) of 23.6 parts of the polyamine isophorone diamine, 981.4 parts of ethyl acetate, and 206.5 parts of isopropyl alcohol was blended, and 755.2 parts of the urethane prepolymer solution obtained earlier was added dropwise while stirring, and the mixture was allowed to react at 40°C for 1 hour. As a result, polyurethane resin emulsion PU1 was obtained, which had a non-volatile content (solids content) of 30%, a viscosity of 1150 mPa·s (25°C), a terminal amino group concentration of 42.8 μg equivalents per 1 g of resin solids, and 84.7% plant-derived components in the resin solids (biomass content 84.7%).

[0153] <White paste> 411 parts of deionized water, 97 parts of dispersant [BYK-190 manufactured by BYK Japan Co., Ltd.], 60 parts of propylene glycol, 1000 parts of titanium oxide [CR-95 manufactured by Ishihara Sangyo Co., Ltd.] and 200 parts of glass beads (diameter 1 mm) were mixed in a disperser at a rotation speed of 3000 min -1 The mixture was dispersed for 120 minutes at 100°C, and then filtered through a 300-mesh wire screen to prepare a white paste. The composition of the white paste is shown in Table 3.

[0154] [Table 3]

[0155] [Example 1] 19.8 parts of the resin emulsion obtained in Production Example 1 was mixed with 2.8 parts of ST200 (manufactured by Nippon Shokubai) as a wax emulsion, and the mixture was mixed in a homodisper at a rotation speed of 1000 min -1While stirring at 50°C, 30 parts of the white paste, 20 parts of propylene glycol (PG), 10 parts of diethylene glycol monobutyl ether (BDG, SP value 9.5), 0.4 parts of a surfactant [KF-6011, manufactured by Shin-Etsu Chemical Co., Ltd.], and ion-exchanged water were added to bring the total to 100 parts, and the mixture was stirred for a further 30 minutes, followed by filtering through a 3 μm filter [MCP-3-C10S, manufactured by Advantec Co., Ltd.] to prepare an aqueous ink.

[0156] [Examples 2 to 12, Comparative Examples 1 and 2] Water-based inks of Examples 2 to 12 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the compositions shown in Tables 4 and 5 were used.

[0157] <Preparation of inkjet print 1 (test sheet (PET))> The aqueous ink was filled into a print evaluation device (manufactured by Genesis Co., Ltd.) equipped with an inkjet print head (manufactured by Kyocera Corporation, product number: KJ4B-YH06WST-STDV) in air at a temperature of 25±1°C and a relative humidity of 30±5%. Next, the print evaluation device was set to a head voltage of 26 V, a frequency of 4 kHz, a droplet volume of 12 pL (picoliters), a head temperature of 32°C, a resolution of 600 dpi, and a negative pressure of -4.0 kPa. A corona-treated polyester film (PET) (manufactured by Futamura Chemical Co., Ltd., product name: Taiko Polyester Film FE2001) was used as the recording medium. The corona-treated polyester film was fixed to a conveying table so that its longitudinal direction was aligned with the conveying direction. A print command was transmitted to the print evaluation device, and a solid image was printed on the corona-treated polyester film using an inkjet recording method with a 100% ink coverage (12 pL, 600 × 600 dpi). Immediately after printing, the corona-treated polyester film was dried for 10 seconds in a dryer at 100°C to obtain a test sheet (PET).

[0158] <Preparation of inkjet print 2 (test sheet (OPP))> A test sheet (OPP) was obtained in the same manner as in Preparation of Inkjet Printed Material 1 (Test Sheet (PET)), except that the recording medium was changed from a corona-treated polyester film (PET) [manufactured by Futamura Chemical Co., Ltd., trade name: Taiko Polyester Film FE2001] to a corona-treated OPP film [manufactured by Futamura Chemical Co., Ltd., trade name: FOR-AQ].

[0159] -Evaluation method- <Scratch resistance> The printed image on the test sheet (PET) was rubbed with a nylon nonwoven fabric, and the adhesion to the substrate was evaluated based on the following evaluation criteria. The evaluation results for each example and comparative example are shown in Tables 4 and 5. [Evaluation criteria] 5: The printed image does not peel off even when rubbed. 4: When the printed image is rubbed, the image peels off very slightly. 3: When the printed image is rubbed, the image peels off slightly. 2: When the printed image is rubbed, the image peels off slightly. 1: When the printed image is rubbed, the image clearly peels off. 0: The printed image peels off easily when rubbed.

[0160] <Adhesion (PET)> The printed image on the test sheet (PET) was rubbed with a fingernail, and the adhesion to the substrate was evaluated based on the following evaluation criteria. The evaluation results for each of the Examples and Comparative Examples are shown in Tables 4 and 5. [Evaluation criteria] 5: The printed image does not peel off at all even when rubbed with the fingernail. 4: When you rub the printed image with your fingernail, the image peels off very slightly. 3: When you rub the printed image with your fingernail, the image peels off slightly. 2: When you rub the printed image with your fingernail, the image peels off slightly. 1: When you rub the printed image with your fingernail, the image clearly peels off. 0: When the printed image is rubbed with the fingernail, the image peels off easily.

[0161] <Adhesion (OPP)> The evaluation was carried out under the same conditions as in <Adhesion (PET)>, except that the test sheet (PET) was replaced with the test sheet (OPP). The evaluation results for each example and comparative example are shown in Tables 4 and 5.

[0162] <Blocking resistance> A polyester film that has not been corona treated is placed on the printed surface of the test sheet (PET), and a pressure of 2 N / cm is applied to the polyester film in air at 25°C. 2 After applying the load for 1 hour, the polyester film was quickly peeled off, and the resistance felt at that time was observed, and the blocking resistance was evaluated based on the following evaluation criteria. The evaluation results of each example and comparative example are shown in Tables 4 and 5. [Evaluation criteria] 5: No resistance is felt when peeling off the polyester film. 4: Very little resistance is felt when peeling off the polyester film. 3: There is only a slight resistance when peeling off the polyester film. 2: Resistance is clearly felt when peeling off the polyester film. 1: There is a strong resistance when peeling off the polyester film. 0: Very strong resistance is felt when peeling off the polyester film.

[0163] <Adhesive tape peeling resistance> An adhesive tape (Nichiban Co., Ltd., Cellotape (registered trademark) No. 405, 24 mm wide) was applied to the printed surface of the test sheet (OPP) at room temperature and left to stand for 1 minute. The tape was then peeled off in a 180° direction and the adhesive tape peel resistance was evaluated based on the following evaluation criteria. The evaluation results for each example and comparative example are shown in Tables 4 and 5. [Evaluation criteria] 5: The printed image does not peel off at all. 4: 1 to 20% of the printed image peels off. 3: 21-50% of the printed image peels off. 2: 51-75% of the printed image peels off. 1: 76-100% of the printed image peels off.

[0164] <Biomass ratio> The biomass degree in the non-volatile content of the resin emulsions of Production Examples 1 to 9 and the biomass degree in the non-volatile content (ink solid content) of the water-based inks of the Examples and Comparative Examples were calculated from the content (mass %) of the biomass component. The biomass degree in Production Example 1 was calculated as follows. {Biomass monomer IBOA (322 + 310) parts x biomass content 73% / 1000 parts} x 100 (%) =46% The biomass content in the nonvolatile content of the resin emulsion in each production example is shown in Tables 1 and 2. The biomass degree in Example 1 was calculated as follows. {Resin emulsion 19.8 parts x non-volatile content (50%) x biomass content (46%) / non-volatile content (31.3 parts)} x 100 =4.6 / 31.3×100(%)=15% Tables 4 and 5 show the biomass content of the ink solids in the aqueous inks of the respective Examples and Comparative Examples.

[0165] <Water resistance> The water resistance was determined by measuring the 60° specular gloss of the test sheet (PET) before and after the water resistance immersion using a gloss meter (product number VG-7000, manufactured by Nippon Denshoku Industries Co., Ltd.). Specifically, the test sheet (PET) was immersed in 40°C warm water for 24 hours (water resistance test), the water was thoroughly wiped off, and the gloss of the test sheet (PET) was measured using the gloss meter. Formula: [Gloss retention (%)] = [[Gloss after water resistance test] ÷ [Gloss before water resistance test]] × 100 The gloss retention was calculated based on the following criteria. The water resistance was evaluated based on the gloss retention value. 5: Gloss retention rate is 80% or more 3: Gloss retention is 70% or more but less than 80% 1: Gloss retention is less than 70%

[0166] <Weather resistance> Weather resistance was determined by measuring the 60° specular gloss of the test sheet (PET) before and after the following weather resistance test using a gloss meter (product number VG-7000, manufactured by Nippon Denshoku Industries Co., Ltd.). Weather resistance test conditions Installation conditions: South facing, 30 degrees, direct exposure (exposure location: Suita City, Osaka Prefecture / on the premises of Nippon Shokubai Co., Ltd.) Test period: 2 months Gloss retention calculation formula Formula: [Gloss retention (%)] = [[Gloss after weather resistance test] ÷ [Gloss before weather resistance test]] × 100 Weather resistance evaluation criteria 5: Gloss retention rate is 80% or more 3: Gloss retention is 70% or more but less than 80% 1: Gloss retention is less than 70%

[0167] [Table 4] [Table 5] [Industrial Applicability]

[0168] The acrylic resin for ink of the present invention can be suitably used as a resin to be contained in inks such as inkjet inks, flexographic printing inks, offset printing inks, lithographic printing inks, gravure printing inks, and screen printing inks.

Claims

1. Contains acrylic resin with a biomass content of 10% or more, the acrylic resin comprises an acrylic polymer containing a structural unit derived from a (meth)acrylate having a branched alkyl group, a structural unit derived from a (meth)acrylate having a cyclic aliphatic group, and a structural unit derived from a reactive emulsifier having a polymerizable group; a content ratio of the structural unit derived from the (meth)acrylate having a branched alkyl group in 100 parts by mass of the acrylic polymer is 10 parts by mass or more and 70 parts by mass or less; a content ratio of the structural unit derived from the (meth)acrylate having a cyclic aliphatic group relative to 100 parts by mass of the acrylic polymer is 30 parts by mass or more and 90 parts by mass or less; The aqueous dispersion for aqueous ink, wherein the acrylic resin is present as emulsion particles having an average particle size of 100 to 300 nm.

2. 2. The aqueous dispersion for aqueous ink according to claim 1, wherein the (meth)acrylate having a cycloaliphatic group is an ester of a cycloaliphatic hydrocarbon having one hydroxyl group and (meth)acrylic acid.

3. 2. The aqueous dispersion for aqueous ink according to claim 1, wherein the ratio of the structural unit derived from a (meth)acrylate having a cyclic aliphatic group to 100 parts by mass of the acrylic polymer is 30 parts by mass or more and 80 parts by mass or less.

4. The aqueous dispersion for aqueous ink according to claim 1, wherein the cycloaliphatic group is a group derived from a terpene.

5. 2. The aqueous dispersion for an aqueous ink according to claim 1, wherein a content of the structural units derived from a (meth)acrylate having a cyclic aliphatic group relative to 100 parts by mass of structural units derived from an alkyl or alkenyl (meth)acrylate contained in the acrylic polymer is 30 parts by mass or more and 95 parts by mass or less.

6. The acrylic polymer contains structural units derived from a hydroxyl group-containing (meth)acrylate, The aqueous dispersion for aqueous ink according to claim 1 , wherein the content of the structural unit derived from the hydroxyl group-containing (meth)acrylate in 100 parts by mass of the acrylic polymer is 0.1 parts by mass or more and 30 parts by mass or less.

7. The acrylic polymer may contain structural units derived from an acid group-containing monomer, The aqueous dispersion for aqueous ink according to claim 1 , wherein the content of the structural unit derived from the acid group-containing monomer in 100 parts by mass of the acrylic polymer is 10 parts by mass or less.

8. The acrylic polymer contains structural units derived from a styrene-based monomer, The aqueous dispersion for aqueous ink according to claim 1 , wherein the content of the structural unit derived from the styrene-based monomer in 100 parts by mass of the acrylic polymer is 10 parts by mass or more and 60 parts by mass or less.

9. 4. The aqueous dispersion for aqueous ink according to claim 1, wherein the acrylic resin has an acid value of 20 mgKOH / g or less.

10. 4. The aqueous dispersion for aqueous ink according to claim 1, wherein the minimum film-forming temperature is 0°C or higher and 100°C or lower.

11. An aqueous ink comprising the aqueous dispersion according to any one of claims 1 to 3.

12. The aqueous ink of claim 11 further comprising a polymeric wax.

13. The aqueous ink of claim 11, which is an aqueous inkjet ink.

14. A laminate having a layer containing the water-based ink according to claim 11 on a printing substrate.

15. A method for producing a laminate, comprising the step of applying the water-based ink according to claim 11 onto a printing substrate.

16. A method for producing the aqueous dispersion for aqueous ink according to any one of claims 1 to 3 by emulsion polymerization.

17. The method according to claim 16, wherein the emulsion polymerization is carried out using an emulsifier having a polymerizable group.

Images