JP7240471B2 - Binder component and emulsion - Google Patents

Description

The present invention relates to binder components and emulsions.

Inkjet printing is used in a wide variety of applications such as personal use, office use, business use, recording use, color display use, and color photograph use, due to its high functionality. Furthermore, in recent years, the range of application has expanded from conventional consumer-type inkjet printers for offices and wide-format inkjet printers for large-format printing to inkjet printers for industrial use. Since inkjet printing does not require a plate for image printing, it is suitable as a printing method capable of obtaining industrial printed matter in small quantities and in a wide variety of products on demand. Inkjet printing using water-based inkjet inks has been actively proposed in consideration of the environment.

Industrial applications include sign displays, outdoor advertisements, facility signs, displays, POP advertisements, traffic advertisements, packaging, containers, labels, and the like. Print substrates (recording media) applicable to these applications include paper media such as paper, cardboard, photo paper, and inkjet paper; plastic media such as polyvinyl chloride, polyolefin, polyester, and nylon; Fabrics such as cloth, nylon fabric, and non-woven fabric; Furthermore, for industrial applications, on-demand printing, which does not require plates, is the mainstream, and high-speed printing aptitude is required. Images recorded with water-based inkjet inks containing dyes as colorants are poor in durability such as water resistance and lightfastness, so water-based inkjet inks containing pigments as colorants are used.

In order to record a printed image with improved durability, an inkjet ink containing an acrylic or urethane binder component capable of forming a film has been proposed (Patent Documents 1 and 2). Further, in a water-based pigment inkjet ink, it is necessary to stably finely disperse the pigment. has been proposed (Patent Document 3).

Japanese Patent No. 4157868 Japanese translation of PCT publication No. 2009-515007 WO2013/008691

However, even with the inkjet inks using the pigment dispersions proposed in Patent Documents 1 to 3, it was difficult to record images with excellent durability such as adhesion and abrasion resistance.

By the way, in view of the recent global warming trend, carbon dioxide emission problem, resource problem, marine plastic problem, etc., the importance of environmentally friendly technologies such as energy saving, recycling, and environmentally friendly materials is increasing. . Under these circumstances, dispersants for dispersing pigments, which are blended in conventional water-based inkjet inks and water-based pigment dispersions, are polymers synthesized using raw materials such as monomers derived from petroleum materials. Dispersants are used. That is, images recorded with conventional water-based inkjet inks are formed from materials derived from petroleum materials, and therefore it cannot be said that environmentally friendly technologies are necessarily applied. While printing substrates such as containers and labels made of biodegradable plastics such as polylactic acid and polyhydroxyalkanoic acid are applied to inkjet printing, images recorded on such printing substrates are environmentally friendly. There was a problem that mold technology was not applied.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to form a dry film such as an image having excellent adhesion, abrasion resistance, and blocking resistance. It is an object of the present invention to provide an environmentally friendly binder component and an emulsion that can be used.

That is, according to the present invention, the following binder component is provided.
[1] A binder component that is a polymer that satisfies the following requirements (5) to (9).
[Requirement (5)]:
It is an AB block copolymer containing a polymer chain A2 and a polymer chain B2 in which the content of structural units derived from methacrylic acid-based monomers is 90% by mass or more.
[Requirement (6)]:
The polymer chain A2 is
Containing 80% by mass or more of structural units derived from methacrylates derived from biological materials,
a number average molecular weight of 10,000 to 30,000,
It is a water-insoluble polymer block having a molecular weight distribution of 1.6 or less.
[Requirement (7)]:
The polymer chain B2 is
Containing structural units derived from methacrylic acid,
Containing 40 to 90% by mass of structural units derived from methacrylates derived from biological materials,
an acid value of 50 to 150 mgKOH/g,
a number average molecular weight of 5,000 to 20,000,
It is a polymer block in which at least a portion of the carboxy groups are neutralized with alkali.
[Requirement (8)]:
It has a number average molecular weight of 15,000 to 50,000 and a molecular weight distribution of 1.6 or less.
[Requirement (9)]:
The particles have a number average particle diameter of 10 to 200 nm.
[2] The above-mentioned [1], wherein the methacrylate derived from a biological material is at least one selected from the group consisting of ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate. binder component.
[3] The binder component according to the above [1] or [2], which is used in an aqueous inkjet ink.

Further, according to the present invention, the following emulsions are provided.
[4] An emulsion containing water and binder particles formed from the binder component according to any one of [1] to [3].

According to the present invention, it is possible to provide an environmentally friendly binder component and emulsion capable of forming a dry film such as an image having excellent adhesion, abrasion resistance, and blocking resistance.

<Aqueous Pigment Dispersion>
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. Various physical property values in this specification are values at room temperature (25° C.) unless otherwise specified. Hereinafter, "aqueous pigment dispersion" will be simply referred to as "pigment dispersion", and "aqueous inkjet ink" will be simply referred to as "ink".

The aqueous pigment dispersion of the present invention contains a pigment, water, a water-soluble organic solvent, and a polymeric dispersant for dispersing the pigment. Then, the polymer dispersant contains a structural unit (i) derived from at least one of (meth)acrylic acid and itaconic acid, and a structural unit (ii) derived from a (meth)acrylate derived from a biological material. , an acid value of 30 to 250 mgKOH/g, a content of the structural unit (ii) of 50% by mass or more, a number average molecular weight of 1,000 to 30,000, and a molecular weight distribution (weight average molecular weight/number average molecular weight) is 2.5 or less, and at least part of the carboxy groups are neutralized with an alkali. The details of the aqueous pigment dispersion of the present invention are described below.

(pigment)
As the pigment, an organic pigment or an inorganic pigment can be used. Examples of organic pigments include soluble azo pigments, insoluble azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, isoindoline pigments, perylene pigments, perinone pigments, dioxazine pigments, anthraquinone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, Examples include anthanthrone pigments, indanthrone pigments, flavanthrone pigments, pyranthrone pigments, diketopyrrolopyrrole pigments, and the like. Examples of inorganic pigments include titanium dioxide, iron oxide, antimony pentoxide, zinc oxide, silica, cadmium sulfide, calcium carbonate, barium carbonate, barium sulfate, clay, talc, yellow lead, carbon black, aluminum flakes, and mica pigments. be able to.

Suitable pigments are indicated by their Color Index Number (C.I.), C.I. I. Pigment Blue 15:3, 15:4, 15:6; C.I. I. Pigment Red 122, 176, 254, 269, 291; C.I. I. Pigment Violet 19, 23; C.I. I. Pigment Yellow 74, 150, 155, 180; C.I. I. Pigment Green 36, 58; C.I. I. Pigment Orange 43, 71; C.I. I. Pigment Black 7; C.I. I. Pigments such as Pigment White 6, which are used in ordinary inkjet inks, can be used.

The number average particle size (primary particle size) of the organic pigment is preferably 150 nm or less. The number average particle size (primary particle size) of the inorganic pigment is preferably 300 nm or less. By using a pigment having a number average particle diameter within the above range, it is possible to improve the optical density, chroma, color development, and print quality of the recorded image, and moderately suppress the sedimentation of the pigment in the ink. can do. The number average particle size of the pigment can be measured using, for example, an electron microscope or a light scattering particle size distribution analyzer.

The pigment may be surface-treated with a polymer dispersant, a silane coupling agent, an inorganic substance (silica, zirconia, sulfuric acid, etc.), and a surface treatment agent such as a pigment derivative (synergist). For example, these surface treatment agents may be added or coexisted when synthesizing the pigment, converting the pigment, or refining the pigment. Further, as the quinacridone-based pigment, a composite such as a mixed crystallized product of different pigments or a solid solution pigment can be used. Additionally, the pigment may be treated with a polymeric dispersant or encapsulated. Pigments obtained using raw materials derived from biological materials can also be used. For example, quinacridone-based pigments such as Pigment Red 122 and Pigment Violet 19 can be obtained by using succinic acid obtained from sugarcane or the like.

(liquid medium)
The aqueous pigment dispersion contains a liquid medium containing water and a water-soluble organic solvent as a dispersion medium for the pigment. As the water-soluble organic solvent, alcohol-based solvents, glycol-based solvents, glycol ethers, amide-based solvents, carbonate-based solvents, other polar solvents, and the like can be used.

Examples of alcohol solvents include methanol, ethanol, isopropanol, propyl alcohol, butanol, isobutanol and the like. Examples of glycol-based solvents include ethylene glycol, propylene glycol, glycerin, and the like. Glycol ethers include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, ethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl. ether, tripropylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, 1,3-butane glycol, 3-methoxy-3-methyl-1-butanol and the like. Examples of amide solvents include dimethylformamide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide and the like. Examples of carbonate-based solvents include ethylene carbonate, propylene carbonate, dimethyl carbonate, and the like. Other polar solvents include dimethylsulfoxide, tetramethylurea, dimethylimidazolidinone and the like.

As the water-soluble organic solvent, it is preferable to use a solvent derived from a biological material, a recycled solvent, a biodegradable solvent, a green solvent, or the like. Specifically, ethanol obtained by fermentation methods and after saccharification of sugar cane, corn, and cellulosic materials; 1,3-butanediol and glycerin, which are extracts from natural products; biodegradable 3- Methoxy-3-methyl-1-butanol; ethylene glycol, propylene glycol, and derivatives thereof, which are recycling solvents for various materials such as plastic products; and the like.

The polymer dispersant and the binder component described below are preferably produced by solution polymerization using a water-soluble organic solvent used in aqueous pigment dispersions and aqueous inkjet inks. When these water-soluble organic solvents are used as the polymerization solvent, the polymer solution obtained by polymerization can be used as it is to prepare an aqueous pigment dispersion or an aqueous inkjet ink, so that the process can be simplified.

(Polymer dispersant)
A polymeric dispersant is a polymer containing a structural unit (i) derived from at least one of (meth)acrylic acid and itaconic acid. Since itaconic acid is a monomer obtained by fermentation, it is an environmentally friendly material. By using these monomers, a carboxyl group can be introduced into the polymer used as the polymer dispersant. In addition, the polymer (polymeric dispersant) can be dissolved in water by ionizing the introduced carboxyl groups by neutralizing them with an alkali.

The amount of carboxy groups in the polymer is defined by the acid number of the polymer. Specifically, the acid value of the polymer used as the polymer dispersant is 30-250 mgKOH/g, preferably 50-230 mgKOH/g. If the acid value is less than 30 mgKOH/g, the polymer becomes difficult to dissolve in water. On the other hand, when the acid value is more than 250 mgKOH/g, the hydrophilicity of the polymer becomes excessively high, so that it is likely to detach from the pigment, resulting in a decrease in the dispersion stability of the pigment or deterioration of the recorded image (dry film). water resistance is reduced.

A polymeric dispersant is a polymer containing a structural unit (ii) derived from a (meth)acrylate derived from a biological material. The term "biological (meth)acrylate" as used herein means "(meth)acrylate derived from alcohol derived from biological material". That is, "biological (meth)acrylate" is a (meth)acrylate synthesized using alcohol derived from a biological material as a material, and the ester residue containing oxygen of the ester bond other than the (meth)acryloyl group is , are alcohol residues derived from biological materials.

Alcohols derived from biological materials include ethanol, methanol, isopropanol, isobutanol, and lactic acid obtained by fermentation; glucose, glycerin, isosorbide, and glycerol, which are derivatives of glycerin, obtained by decomposing sugars, starches, and fats and oils. Formide; benzyl alcohol and phenethyl alcohol, which are raw materials for fragrances extracted from natural products; tetrahydrofurfural, which is a hydrogen reduction product of furfural obtained from corn cobs; Dodecyl alcohol, tetradecyl alcohol, stearyl alcohol, oleyl alcohol, and behenyl alcohol; 3-pentadecylphenol, 3-pentadecylphenolmonoene, and 3-pentadecylphenoldiene obtained from cashew nuts and the like; sinapyl, a constituent of lignin alcohols, coniferyl alcohol, p-coumaryl alcohol, etc.; geraniol, nilaol, neol, menthol, terpineol, and borneol obtained by plant refining; rosin; monol;

The biological material-derived (meth)acrylate is an ester of the above biological material-derived alcohol and (meth)acrylic acid, for example, methyl (meth) acrylate, ethyl (meth) acrylate, glyceryl mono (meth) Acrylate, benzyl (meth)acrylate, phenethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate and the like. can.

(Meth)acrylates derived from biological materials can be distinguished from (meth)acrylates derived from petroleum materials because they are obtained from biological materials. Furthermore, while compounds derived from petroleum materials do not contain carbon 14 ( ¹⁴ C), which is one of the carbon isotopes, compounds derived from biological materials, especially plant materials, contain carbon 14 ( ¹⁴ C). is included, it is possible to determine whether the (meth)acrylate is derived from a biological material based on the presence or absence of carbon-14 ( ¹⁴ C). Methods for measuring ¹⁴ C include beta ray measurement and accelerator mass spectrometry (AMS). In particular, environmental materials are specified in bio-based concentration test standard ASTM D6866, European standard CEN16137, ISO international standard ISO16620-2, and the like.

The content of the structural unit (ii) in the polymer used as the polymer dispersant is 50% by mass or more. Since the content of the structural unit (ii) in the polymer is 50% by mass, it can be used as an environmentally friendly polymer dispersant, and an ink containing this polymer as a polymer dispersant can be used. Images and printed matter can be environmentally friendly printed matter and the like.

The biomass degree of the polymer can be calculated from the carbon number of the alcohol residue derived from the biological material, which accounts for the total carbon number of the monomers constituting the polymer used as the polymer dispersant. For example, in the case of ethyl acrylate (total carbon number = 5), the biomaterial-derived ethanol residue has 2 carbon atoms, so the biomass degree is "2/5 x 100 = 40%". The biomass degree of preferred (meth)acrylates calculated in the same manner is 33.3% ethyl methacrylate, 62.5% tetrahydrofurfuryl acrylate, 55.5% tetrahydrofurfuryl methacrylate, 76.9% isobornyl acrylate, iso Bornyl methacrylate 71.4%, octyl acrylate 72.7%, octyl methacrylate 66.6%, lauryl acrylate 80%, lauryl methacrylate 75%, stearyl acrylate 85.7%, stearyl methacrylate 81.8%.

The polymer used as the polymer dispersant contains structural units other than the structural units (i) and (ii), for example, structural units derived from radically polymerizable monomers derived from petroleum materials (other monomers). good too. Examples of other monomers include vinyl-based monomers such as styrene and vinyltoluene; (meth)acrylic acid-based monomers; and the like. (Meth)acrylic acid-based monomers include methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl, isostearyl, behenyl, cyclohexyl, trimethylcyclohexyl, and t-butylcyclohexyl. , benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, nonylphenoxyethyl, isobornyl, dicyclopentanyl, dicyclopentenyl, dicyclopentenyloxyethyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 4-hydroxybutyl , dimethylaminoethyl, diethylaminoethyl, polyethylene glycol, polypropylene glycol, polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether, polyepsiloncaprolactone, and polydimethylsiloxane. Among them, a monomer having a polyalkylene glycol chain is preferable because the polyalkylene glycol chain is biodegradable and thus an environmentally friendly monomer. It is preferable that the polymer used as the polymer dispersant is substantially composed only of the above structural units (i) and (ii).

The polymeric dispersant is a polymer having a number average molecular weight (Mn) of 1,000 to 30,000, preferably 2,000 to 25,000, more preferably 3,000 to 20,000. When the Mn of the polymer is less than 1,000, it is likely to be detached from the pigment, and the dispersion stability of the pigment is lowered. On the other hand, when the Mn of the polymer exceeds 30,000, the viscosity of the pigment dispersion liquid becomes too high, and the particles of the pigment tend to adhere to each other and aggregate. Both the number average molecular weight (Mn) and the weight average molecular weight (Mn) in this specification are polystyrene-equivalent values measured by gel permeation chromatography (GPC).

The polymeric dispersant is a polymer having a molecular weight distribution (PDI=weight average molecular weight (Mw)/number average molecular weight (Mn)) of 2.5 or less, preferably 2.0 or less, more preferably 1.5 or less. . When the molecular weight distribution (PDI) is more than 2.5, the dispersibility of the pigment is lowered. By living radical polymerization, the molecular weight of the resulting polymer can be made uniform and the structure can be controlled. By making the molecular weights of the polymers uniform, high-molecular-weight polymers and low-molecular-weight polymers are reduced, and more polymer chains that contribute to the dispersibility of the pigment are contained, which is preferable.

A polymer dispersant is a polymer in which at least part of the carboxy groups derived from (meth)acrylic acid, itaconic acid, or the like are neutralized with an alkali. At least part of the carboxyl groups are neutralized and ionized, so the polymer has affinity and solubility in water.

Alkalis include ammonia; organic amines such as triethylamine, dimethylaminoethanol, diethanolamine, triethanolamine, aminomethylpropanol, and polyethylene glycol polypropylene glycol monoamine; coconutamine, octylamine, dodecylamine, stearylamine, oleylamine, dimethyloctylamine, and the like. organic monoamines derived from biological materials; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide; and the like.

Among them, highly volatile ammonia that does not contain organic matter; aminomethylpropanol derived from amino acids; dimethylaminoethanol, octylamine, and dodecylamine obtained from plants, etc.; alkali metals such as lithium hydroxide, sodium hydroxide, and potassium hydroxide Hydroxide; is preferable for environmental protection. Further, alkalis include ammonia, dimethylaminoethanol, 2-amino-1-propanol, sodium hydroxide, potassium hydroxide, lithium hydroxide, linear aliphatic amines having 6 to 22 carbon atoms, and Branched aliphatic amines and unsaturated aliphatic amines having 6 to 22 carbon atoms are preferred.

A polymer used as a polymer dispersant can be produced by a conventionally known method. Specifically, it is preferable to synthesize by solution polymerization using a water-soluble organic solvent used for the pigment dispersion. For example, an azo-based polymerization initiator or a peroxide-based polymerization initiator is used, and polymerization is performed while dropping the monomers into a water-soluble organic solvent or charging them all at once. At the time of polymerization, a chain transfer agent such as thiols or bromomethyl acrylate may be used in combination in order to adjust the molecular weight of the resulting polymer. Moreover, in order to make the molecular weight of the obtained polymer uniform, it may be synthesized by a living radical polymerization method. Living radical polymerization methods include atom transfer radical polymerization method; NMP method using nitroxide, etc.; reversible addition-fragmentation chain transfer polymerization method using thioester, thiocarbonate, etc.; TERP method using organic tellurium as an initiator; An iodine transfer polymerization method using a compound as an initiator; a reversible transfer catalyst polymerization method or a reversible catalyst-mediated polymerization method using an inorganic or organic catalyst; a chain transfer polymerization method using a cobalt catalyst or the like;

The polymeric dispersant is preferably a polymer that satisfies the following requirements (1) to (4).

[Requirements (1)]:
It is an AB block copolymer containing polymer chain A1 and polymer chain B1 in which the content of structural units derived from methacrylic acid-based monomers is 90% by mass or more.
[Requirement (2)]:
Polymer chain A1 is
Containing 80% by mass or more of the structural unit (ii-a) derived from a methacrylate derived from a biological material,
a number average molecular weight of 1,000 to 10,000,
It is a water-insoluble polymer block having a molecular weight distribution of 1.6 or less.
[Requirement (3)]:
Polymer chain B1 is
Containing a structural unit (ib) derived from methacrylic acid,
Containing 40 to 90% by mass of structural units (ii-b) derived from methacrylates derived from biological materials,
an acid value of 50 to 260 mgKOH/g,
a number average molecular weight of 1,000 to 10,000,
It is a polymer block in which at least a portion of the carboxy groups are neutralized with alkali.
[Requirement (4)]:
It has a number average molecular weight of 2,000 to 20,000 and a molecular weight distribution of 1.6 or less.

This polymeric dispersant is an A- It is a B block copolymer. The A1 chain is a water-insoluble polymer block, and the B1 chain is a water-soluble polymer block in which at least part of the carboxy groups derived from methacrylic acid are neutralized with alkali.

Since the A1 chain is a water-insoluble polymer block, it is highly hydrophobic and easily interacts with a water-insoluble pigment. Therefore, the A1 chain can be adsorbed or deposited on the pigment by hydrogen bonding or the like, thereby encapsulating the pigment. Also, since the A1 chain has a high molecular weight, it hardly leaves the pigment. Furthermore, since the A1 chains are adsorbed to the pigment and the B1 chains are dissolved in water, the finely dispersed pigments undergo steric repulsion and the finely dispersed state is maintained for a long period of time. In addition, the polymer dispersant that is free or dissolved in the liquid medium is small, or even if it is free, the A1 chain is water-insoluble and forms particles, so that the ejection stability of the water-based inkjet ink can be improved. It is possible to provide an ink suitable for high-speed printing.

The B1 chain is a water soluble polymer block. Since the polymer dispersant is adsorbed on the pigment, even when the ink containing the polymer dispersant is dried with an inkjet head or the like, the polymer dispersant is difficult to detach from the adsorbed pigment. For this reason, the pigment hardly aggregates, and the detached polymer dispersant hardly forms a film, so it has excellent resolubility and can be dispersed by adding an aqueous liquid medium. can be easily returned.

(Requirement (1))
The polymeric dispersant is an AB block copolymer containing polymer chain A1 and polymer chain B1 in which the content of structural units derived from methacrylic acid-based monomers is 90% by mass or more. Methacrylic acid-based monomers are methacrylic acid and methacrylate, which is an esterified product of methacrylic acid. AB block copolymers are polymers with precisely controlled structures and can be prepared by living polymerization, especially living radical polymerization. Using an organic iodide as a starting compound and producing an AB block copolymer by living radical polymerization using an organic compound as a catalyst makes it possible to use environmentally friendly materials and has a high degree of freedom in polymer design. preferred for In the case of living radical polymerization using an organic iodide, the iodine atom, which is a terminal propagating group, is preferably bound to a tertiary carbon atom, so the AB block copolymer has a structure derived from a methacrylic acid-based monomer. The unit content is 90% by mass or more. Further, when the content of structural units derived from methacrylic acid-based monomers is high, the AB block copolymer has a high glass transition temperature, so that images with improved thermal properties such as heat resistance can be recorded. Furthermore, methacrylic acid-based monomers have higher hydrolysis resistance than acrylic acid-based monomers such as acrylic acid esters, so they are relatively stable and are less likely to be hydrolyzed even in aqueous liquid media. In particular, the AB block copolymer preferably contains 100% by mass of structural units derived from methacrylic acid-based monomers.

As the methacrylic acid-based monomer, it is preferable to use methacrylic acid and a methacrylate derived from a biological material. Furthermore, methacrylates derived from petroleum materials may be used.

(Requirement (2))
The polymer chain A1 contains 80% by mass or more of the structural unit (ii-a) derived from a methacrylate derived from a biological material, has a number average molecular weight of 1,000 to 10,000, and has a molecular weight distribution of 1.6 or less. It is a water-insoluble polymer block. That is, the A1 chain is a polymer block that can adsorb and deposit on pigments, encapsulating them.

In the A1 chain, the content of the structural unit (ii-a) derived from the biological material-derived methacrylate is 80% by mass or more, preferably 90% or more. If the content of the structural unit (ii-a) in the A1 chain is less than 80% by mass, environmental consideration may be somewhat insufficient. In addition, as long as the content of the structural unit (ii-a) is 80% by mass or more, a structural unit derived from a methacrylate derived from a petroleum raw material may be included. Furthermore, as long as the A1 chain is a water-insoluble polymer block, it may contain, for example, about 0.5 to 5% by mass of structural units derived from methacrylic acid.

The A1 chain is a polymer block whose Mn is between 1,000 and 10,000, preferably between 2,000 and 8,000. Since the molecular weight of the A1 chain is relatively large, it is easily adsorbed and deposited on the pigment and can encapsulate the pigment. If the Mn of the A1 chain is less than 1,000, it may easily dissolve in a liquid medium such as a water-soluble organic solvent and may be released from the pigment. On the other hand, when the Mn of the A1 chain exceeds 10,000, it tends to become water-insoluble, and may become difficult to adsorb to the pigment.

The A1 chain is a polymer block of relatively uniform molecular weight having a molecular weight distribution (PDI) of 1.6 or less, preferably 1.5 or less. If the PDI of the A1 chain is more than 1.6, a large amount of polymer blocks outside the above Mn range will be included, making it somewhat difficult to improve the dispersibility of the pigment.

(Requirement (3))
Polymer chain B1 contains a structural unit (ib) derived from methacrylic acid, contains 40 to 90% by mass of a structural unit (ii-b) derived from a methacrylate derived from a biological material, and has an acid value of 50 to 260 mgKOH/ g, a number average molecular weight of 1,000 to 10,000, and at least a portion of the carboxy groups being neutralized with an alkali. That is, the B1 chain is a water-soluble polymer block in which at least part of the carboxy groups are neutralized with an alkali and ionized to dissolve in water.

The B1 chain is a polymer block having a carboxy group derived from methacrylic acid and having an acid value of 50 to 260 mgKOH/g, preferably 60 to 200 mgKOH/g, more preferably 70 to 150 mgKOH/g. With an acid value within this range, at least a portion of the carboxy groups can be neutralized to form polymer blocks that are soluble in water. If the acid value of the B1 chain is less than 50 mgKOH/g, it may not be dissolved in water even after neutralization. On the other hand, when the acid value of the B1 chain exceeds 260 mgKOH/g, the hydrophilicity may become too high. For this reason, the water resistance of the recorded image (dry film) may be easily lowered, and the content of structural units derived from methacrylate derived from biological materials is relatively reduced, so environmental compatibility is improved. may decrease.

Even when the ink containing the AB block copolymer as a polymeric dispersant dries, the B1 chain dissolves in water, so it can be easily returned to a dispersed state by applying an aqueous liquid medium. can. Since the water-insoluble A1 chain is adsorbed and deposited on the pigment, it is difficult to detach from the pigment even when the ink dries, and the dispersion can be returned to a good state.

In the B1 chain, the content of structural units (ii-b) derived from methacrylates derived from biological materials is 40 to 90% by mass. Therefore, AB block copolymers are environmentally friendly polymeric dispersants.

The B1 chain is a polymer block whose Mn is between 1,000 and 10,000, preferably between 2,000 and 8,000, more preferably between 3,000 and 6,000. In the present specification, the "number average molecular weight (Mn) of the B chain" is "a value obtained by subtracting the number average molecular weight (Mn) of the A chain from the number average molecular weight (Mn) of the entire AB block copolymer". be. If the Mn of the B1 chain is less than 1,000, the water solubility of the B1 chain may be slightly insufficient, resulting in insufficient dispersion stability of the pigment. On the other hand, when the Mn of the B1 chain is more than 10,000, even if the A1 chain is adsorbed to the pigment, the polymer as a whole may easily detach, and the viscosity of the aqueous pigment dispersion may excessively increase. There is

The B1 chain is a water-soluble polymer block in which at least part of the carboxy groups are neutralized with an alkali and ionized to dissolve in water. As the alkali, the aforementioned ammonia, organic amines, alkali metal hydroxides, and the like can be used. All of the carboxy groups may be neutralized with an alkali, or part of the carboxy groups may be neutralized to the extent that the B1 chain is soluble in water.

(Requirement (4))
The Mn of the AB block copolymer is from 2,000 to 20,000, preferably from 3,000 to 15,000, more preferably from 5,000 to 12,000. If the Mn of the AB block copolymer is less than 2,000, it may be easily released from the pigment. On the other hand, when the Mn of the AB block copolymer exceeds 20,000, the viscosity may excessively increase during polymerization, or the viscosity of the aqueous pigment dispersion may excessively increase.

The AB block copolymer has a molecular weight distribution (PDI) of 1.6 or less, preferably 1.5 or less. If the AB block copolymer has a PDI of more than 1.6, it will contain a large amount of Mn outside the above range, and the dispersibility of the pigment may be somewhat insufficient.

(Method for producing AB block copolymer)
The above AB block copolymer used as a polymeric dispersant can be produced according to a conventionally known method. For example, it can be produced by living anionic polymerization, living cationic polymerization, or living radical polymerization. Among them, living radical polymerization is preferable from the viewpoint of conditions, materials, equipment, and the like.

Living radical polymerization includes atom transfer radical polymerization (ATRP method), nitroxide-mediated radical polymerization (NMP method), reversible addition-fragmentation chain transfer polymerization (RAFT method), organic tellurium-based living radical polymerization (TERP method), There are reversible transfer catalyst polymerization (RTCP method), reversible catalyst mediated polymerization (RCMP method), and the like. Among them, the RTCP method and the RCMP method, which use an organic iodide as a starting compound and an organic compound as a catalyst, are advantageous in terms of cost because they do not require heavy metals or special compounds, and are easy to purify and process. It is also advantageous in terms of

In the case of the RTCP method and the RCMP method, since the iodine atom, which is a terminal propagating group, is bound to a tertiary carbon atom, a stabilized radical is easily generated, resulting in an AB block copolymer having a specific block structure. It is preferable because it can be easily manufactured with high precision using general equipment. Therefore, it is preferable that the content of structural units derived from methacrylic acid-based monomers in the AB block copolymer is 90% by mass or more.

AB block copolymers may be produced by any type of polymerization, including solventless, solution polymerization, and emulsion polymerization. Among them, solution polymerization in an organic solvent is preferred, and solution polymerization in the same organic solvent as the water-soluble organic solvent mixed in the aqueous pigment dispersion is more preferred. As a result, the AB block copolymer can be used as it is in the aqueous pigment dispersion without taking it out. The above RTCP method and RCMP method can be carried out in the aqueous organic solvent used for the aqueous pigment dispersion.

Either the A1 chain or the B1 chain polymer block may be polymerized first. It is preferred to polymerize the B1 chain after polymerizing the A1 chain. If the B1 chain is polymerized first and the polymerization rate is less than 100%, the structural unit derived from the remaining monomer may be introduced into the A1 chain that is polymerized later. In this case, a large amount of methacrylic acid, which is a component of the B1 chain, is introduced into the A1 chain, which may make the A1 chain more soluble in water.

(Aqueous pigment dispersion)
The aqueous pigment dispersion of the present invention is suitable as a pigment dispersion for aqueous inkjet inks. The pigment content in the aqueous pigment dispersion is preferably 5 to 60% by mass. When the pigment is an organic pigment, the content of the organic pigment in the aqueous pigment dispersion is preferably 5 to 30% by mass, more preferably 10 to 25% by mass. In addition, when the pigment is an inorganic pigment, the content of the inorganic pigment in the aqueous pigment dispersion is preferably 20 to 60% by mass, more preferably 30 to 50% by mass, because the inorganic pigment has a large specific gravity. is more preferred.

The water content in the aqueous pigment dispersion is preferably 20 to 80% by mass. A water-based inkjet ink can be prepared by preparing a water-based pigment dispersion containing an appropriate amount of water.

The content of the water-soluble organic solvent in the aqueous pigment dispersion is preferably 30 mass % or less, more preferably 0.5 to 20 mass %. If the content of the water-soluble organic solvent exceeds 30% by mass, the recorded image may be difficult to dry.

The content of the polymeric dispersant in the aqueous pigment dispersion is preferably 0.5 to 20% by mass. If the content of the polymeric dispersant is less than 0.5% by mass, it may be somewhat difficult to stably disperse the pigment. On the other hand, if the content of the polymer dispersant exceeds 20% by mass, the viscosity becomes too high and non-Newtonian viscosity is exhibited, which may make it somewhat difficult to eject linearly by an inkjet method. be.

It is also preferable to set the content of the polymer dispersant in the aqueous pigment dispersion according to the type of pigment, surface properties, particle size, and the like. Specifically, the polymeric dispersant is preferably 5 to 50 parts by mass, more preferably 10 to 30 parts by mass, per 100 parts by mass of the organic pigment. Further, the content of the polymer dispersant is preferably 1 to 20 parts by mass, more preferably 3 to 10 parts by mass, based on 100 parts by mass of the inorganic pigment.

(other ingredients)
The aqueous pigment dispersion may further contain an alkali for neutralizing the polymer dispersant or adjusting the pH. As the alkali, the above-mentioned alkali can be used. The content of alkali in the aqueous pigment dispersion is preferably 0.5 to 5% by mass.

The aqueous pigment dispersion may contain a surfactant. By containing the surfactant, the surface tension of the ink can be maintained at a predetermined value. Examples of surfactants include silicone-based, acetylene glycol-based, fluorine-based, alkylene oxide-based, and hydrocarbon-based surfactants. It is preferable that a surfactant derived from a natural product or a biological material is used. For example, polyalkylene glycol esters using fatty acids such as palm oil and coconut oil, fatty alcohols, ether-based surfactants, and the like are preferable from an environmental point of view. Surfactants generally cause foaming of the ink or cause the ink to be repelled on the film surface. Moreover, since the addition of a surfactant may make the pigments more likely to aggregate, it is preferable to appropriately control the amount of the surfactant added.

The aqueous pigment dispersion may contain a preservative. Preservatives include sodium benzoate, benzimidazole, thiabendazole, potassium sorbitanate, sodium sorbitanate, sodium dehydroacetate, thiazosulfamide, pyridinethiol oxide and the like. The content of the antiseptic in the ink is preferably 0.05 to 2.0% by mass, more preferably 0.1 to 1.0% by mass, based on the total amount of the ink.

If necessary, the aqueous pigment dispersion liquid may contain an organic solvent other than the water-soluble organic solvent described above, a leveling agent, a surface tension modifier, a pH modifier, an ultraviolet absorber, a light stabilizer, an antioxidant, a dye, and a filler. , waxes, thickeners, antifoaming agents, antifungal agents, antistatic agents, fine metal particles, magnetic powders, and other additives.

(Physical properties of aqueous pigment dispersion)
The viscosity of the aqueous pigment dispersion can be appropriately set according to the properties of the pigment, the viscosity of the aqueous inkjet ink to be prepared, and the like. When an organic pigment is used, the viscosity of the aqueous pigment dispersion at 25° C. is preferably 3 to 20 mPa·s. When an inorganic pigment is used, the viscosity of the aqueous pigment dispersion at 25° C. is preferably 5 to 30 mPa·s.

The surface tension of the aqueous pigment dispersion at 25° C. is preferably 15 to 45 mN/m, more preferably 20 to 40 mN/m. The surface tension of the aqueous pigment dispersion can be adjusted by, for example, the type and amount of the water-soluble organic solvent, or by adding a surfactant or the like.

(Method for preparing aqueous pigment dispersion)
An aqueous pigment dispersion can be prepared according to a conventionally known method. For example, water and, if necessary, a water-soluble organic solvent are added to prepare a mixture of a pigment, a polymer dispersant, and the like. Then, a paint shaker, ball mill, attritor, sand mill, horizontal media mill, colloid mill, roll mill or the like is used to finely disperse the pigment to prepare a dispersion. Water and a water-soluble organic solvent are added to the prepared dispersion, and if necessary, a binder component (emulsion) and other additives are added to adjust the concentration to a desired level. Furthermore, alkali or the like may be added to adjust the pH. Further, by adding various additives such as surfactants and preservatives as necessary, the desired aqueous pigment dispersion can be obtained. In addition, after mixing and dispersing each component, it is preferable to remove coarse particles using a centrifugal separator or a filter.

In order to make the number average particle diameter (particle size distribution) of the pigment in the desired range, for example, the size of the grinding media used is reduced; the filling rate of the grinding media is increased; the treatment time is lengthened; ; classify with a filter, centrifuge, or the like after pulverization; It is also preferable to use a pigment that has been finely divided in advance by a conventionally known method such as a salt milling method.

<Water-based inkjet ink>
The water-based inkjet ink of the present invention is an ink containing the above-described water-based pigment dispersion. The ink of the present invention can be prepared according to a conventionally known method except for using the aqueous pigment dispersion described above.

Inks typically contain a liquid medium containing water and a water-soluble organic solvent. The content of the water-soluble organic solvent in the ink is preferably 5 to 30% by mass. In addition, the ink can contain various additives that are used in ordinary water-based inkjet inks. Examples of additives include surfactants, organic solvents, humectants, pigment derivatives, dyes, leveling agents, antifoaming agents, ultraviolet absorbers, binder components such as emulsions, preservatives, antibacterial agents, and waxes. . Examples of surfactants that can be used include ether-based nonionic surfactants such as polyethylene glycol alkyl ethers and acetylene-based surfactants, silicone-based surfactants, and fluorine-based surfactants. The surfactant content in the ink is preferably 0.1 to 2% by mass.

The pigment content in the ink is preferably 1 to 5% by mass for organic pigments, and preferably 1 to 10% by mass for inorganic pigments. The content of the polymeric dispersant in the ink is preferably 0.1 to 5% by mass.

The ink is adjusted to have an appropriate viscosity that can be ejected from the nozzles of the recording head by an inkjet method, depending on the type of pigment and the like. For example, when using an organic pigment, the viscosity of the ink is preferably 2 to 10 mPa·s. The viscosity of the ink when inorganic pigments are used is preferably 5 to 30 mPa·s.

The pH of the ink is preferably 7.0 to 10.0, more preferably 7.5 to 9.5. When the pH of the ink is less than 7.0, the dispersant tends to precipitate and the pigment tends to aggregate. On the other hand, when the pH of the ink exceeds 10.0, the alkalinity becomes strong, which may make handling difficult.

The surface tension of the ink is appropriately set according to the performance of the inkjet printer. For example, the ink preferably has a surface tension of 15 to 45 mN/m, more preferably 20 to 40 mN/m.

(binder component)
The inks described above are useful as inks for recording images by printing on paper such as plain paper, photographic printing paper, photo glossy paper, and matte paper. However, when images are recorded by printing on plastic films, plastic moldings, fibers, fabrics, metals, ceramics, etc., it is preferable that the ink further contains a binder component that forms a film. By printing with an ink containing a binder component, the binder component forms a film, and the adhesion, dry rub resistance, wet rub resistance, blocking resistance, chemical resistance, and solvent resistance of the resulting image (dry film). , scratch resistance and the like can be improved. The content of the binder component in the ink is preferably 1 to 10% by mass.

Various polymers can be used as the binder component. Examples of polymers include acrylic polymers, styrene acrylic polymers, urethane polymers, polyester polymers, polyolefin polymers, and the like. These polymers can be used in the form of aqueous solutions, dispersions, and emulsions.

As the acrylic polymer and styrene acrylic polymer, an emulsion having a dispersed particle size (number average particle size) of 50 to 200 nm obtained by polymerizing an acrylic monomer such as styrene or methacrylate in the presence of a surfactant is used. be able to. These polymers are preferably AB block copolymers or ABA block copolymers having a water-insoluble A chain and a water-soluble B chain.

As urethane-based polymers, diisocyanates, polyols, short-chain diols, diol monocarboxylic acids, and the like are reacted, and if necessary, hydrazine, isophorone diamine, etc. are reacted to extend the chain, followed by self-extension using alkaline water. An aqueous dispersion obtained by emulsification and having a dispersed particle size (number average particle size) of 50 to 200 nm can be used. As the diisocyanate, in addition to isophorone diisocyanate and hexamethylene diisocyanate, lysine diisocyanate and pentamethylene diisocyanate derived from natural materials are preferable. Polyols such as castor oil polyols, which are natural materials, are preferable in addition to polycarbonate diols. As the short-chain diol, in addition to diethylene glycol, ethylene glycol derived from natural materials, 1,3-propanediol, isosorbide, and the like are preferable. As the diol monocarboxylic acid, dimethylolpropanoic acid and the like are preferable.

Polyester-based polymers include dibasic acids such as adipic acid and phthalic acid, diols such as ethylene glycol, propylene glycol, neopentyl glycol and cyclohexanedimethanol, and monomers having sulfonic acid groups such as sodium dimethylisophthalic sulfonate. and are dehydrated or dealcoholized to form a polyester, and then water is added with forced stirring to obtain an aqueous dispersion.

As a polyolefin-based polymer, after dissolving an acrylic acid copolymer of polyethylene or polypropylene, a maleic acid graft, etc. in an organic solvent, an alkaline aqueous solution is added while forcibly stirring to form a water dispersion, and then the organic solvent is removed. can be used.

The binder component is preferably a polymer that satisfies requirements (5) to (9) below.

[Requirement (5)]:
It is an AB block copolymer containing a polymer chain A2 and a polymer chain B2 in which the content of structural units derived from methacrylic acid-based monomers is 90% by mass or more.
[Requirement (6)]:
The polymer chain A2 is
Containing 80% by mass or more of structural units derived from methacrylates derived from biological materials,
a number average molecular weight of 10,000 to 30,000,
It is a water-insoluble polymer block having a molecular weight distribution of 1.6 or less.
[Requirement (7)]:
The polymer chain B2 is
Containing structural units derived from methacrylic acid,
Containing 40 to 90% by mass of structural units derived from methacrylates derived from biological materials,
an acid value of 50 to 150 mgKOH/g,
a number average molecular weight of 5,000 to 20,000,
It is a polymer block in which at least a portion of the carboxy groups are neutralized with alkali.
[Requirement (8)]:
It has a number average molecular weight of 15,000 to 50,000 and a molecular weight distribution of 1.6 or less.
[Requirement (9)]:
The particles have a number average particle diameter of 10 to 200 nm.

Polymers satisfying the above requirements (5) to (9) have structures similar to the aforementioned AB block copolymers used as polymeric dispersants. That is, since it is an AB block copolymer obtained using a monomer derived from a biological material, it is environmentally friendly, and by using this polymer as a binder component, adhesion, abrasion resistance, and blocking resistance An excellent image (dry film) can be formed.

[Requirement (5)]
The binder component is an AB block copolymer containing polymer chain A2 and polymer chain B2 in which the content of structural units derived from methacrylic acid-based monomers is 90% by mass or more. Methacrylic acid-based monomers are methacrylic acid and methacrylate, which is an esterified product of methacrylic acid. AB block copolymers are polymers with precisely controlled structures and can be prepared by living polymerization, especially living radical polymerization. Using an organic iodide as a starting compound and producing an AB block copolymer by living radical polymerization using an organic compound as a catalyst makes it possible to use environmentally friendly materials and has a high degree of freedom in polymer design. preferred for In the case of living radical polymerization using an organic iodide, the iodine atom, which is a terminal propagating group, is preferably bound to a tertiary carbon atom, so the AB block copolymer has a structure derived from a methacrylic acid-based monomer. The unit content is 90% by mass or more. Further, when the content of structural units derived from methacrylic acid-based monomers is high, the AB block copolymer has a high glass transition temperature, so that images with improved thermal properties such as heat resistance can be recorded. Furthermore, methacrylic acid-based monomers have higher hydrolysis resistance than acrylic acid-based monomers such as acrylic acid esters, so they are relatively stable and are less likely to be hydrolyzed even in aqueous liquid media. In particular, the AB block copolymer preferably contains 100% by mass of structural units derived from methacrylic acid-based monomers.

As the methacrylic acid-based monomer, it is preferable to use methacrylic acid and a methacrylate derived from a biological material. Furthermore, methacrylates derived from petroleum materials may be used.

[Requirement (6)]
Polymer chain A2 is a water-insoluble polymer block containing 80% by mass or more of structural units derived from a methacrylate derived from a biological material, having a number average molecular weight of 10,000 to 30,000, and a molecular weight distribution of 1.6 or less. is. This A2 chain is a polymer block that exerts effects such as adhesion to the printing substrate and abrasion resistance. In the A2 chain, the content of structural units derived from biological material-derived methacrylate is 80% by mass or more, preferably 90% or more. If the content of the above structural unit in the A2 chain is less than 80% by mass, environmental consideration may be somewhat insufficient. Moreover, as long as the content of the above structural unit is 80% by mass or more, a structural unit derived from a petroleum raw material-derived methacrylate may be included. Furthermore, as long as the A2 chain is a water-insoluble polymer block, it may contain, for example, about 0.5 to 5% by mass of structural units derived from methacrylic acid.

The A2 chain is a polymer block whose Mn is between 10,000 and 30,000, preferably between 11,000 and 25,000. Since the molecular weight of the A2 chain is sufficiently large, it is possible to form an image (dry film) with excellent adhesion to the printing substrate and excellent abrasion resistance. If the Mn of the A2 chain is less than 10,000, the adhesion of the image may slightly deteriorate. On the other hand, when the Mn of the A2 chain exceeds 30,000, the polymerization rate may decrease and the molecular weight distribution tends to be broadened.

The A2 chain is a polymer block of relatively uniform molecular weight with a molecular weight distribution (PDI) of 1.6 or less, preferably 1.5 or less, more preferably 1.4 or less. When the PDI of the A2 chain is more than 1.6, many polymer blocks outside the above Mn range are included.

[Requirement (7)]
Polymer chain B2 contains structural units derived from methacrylic acid, contains 40 to 90% by mass of structural units derived from methacrylate derived from biological materials, has an acid value of 50 to 150 mgKOH/g, and has a number average molecular weight of 5. 000 to 20,000, and at least a portion of the carboxy groups are neutralized with alkali. That is, the B2 chain is a water-soluble polymer block in which at least part of the carboxy groups are neutralized with an alkali and ionized to dissolve in water.

The B2 chain is a polymer block having a carboxy group derived from methacrylic acid and an acid value of 50-150 mgKOH/g, preferably 60-130 mgKOH/g. If the acid value of the B2 chain is less than 50 mgKOH/g, the B2 chain may be difficult to dissolve in water, which may impair the stability of the particles. In addition, the resolubility of the ink may become insufficient. On the other hand, if the acid value of the B2 chain exceeds 150 mgKOH/g, the viscosity of the ink may become excessively high, and the water resistance of the image may become somewhat insufficient.

In the B2 chain, the content of structural units derived from biological material-derived methacrylate is 40 to 90% by mass, preferably 50 to 90% by mass, more preferably 60 to 85% by mass. Therefore, AB block copolymers are environmentally friendly binder components.

The B2 chain is a polymer block whose Mn is between 5,000 and 20,000, preferably between 6,000 and 10,000. Sufficient water-stable granulation of the binder and the high molecular weight of the B chain act as a film of the binder component together with the A chain, contributing to the improvement of the durability of the printed matter. If the Mn of the B2 chain is less than 5,000, the stability of the particles in an aqueous liquid medium may be somewhat insufficient. On the other hand, if the Mn of the B2 chain exceeds 20,000, the viscosity of the ink may excessively increase, or the water resistance of the image may slightly decrease.

The B2 chain is a water-soluble polymer block in which at least part of the carboxy groups are neutralized with an alkali and ionized to dissolve in water. As the alkali, the aforementioned ammonia, organic amines, alkali metal hydroxides, and the like can be used. All of the carboxy groups may be neutralized with an alkali, or part of the carboxy groups may be neutralized to the extent that the B2 chain is soluble in water. Specifically, from the viewpoint of pH stability and the like, it is preferable that 90 mol % or more of the carboxy groups are neutralized.

[Requirement (8)]
The Mn of the AB block copolymer is from 15,000 to 50,000, preferably from 16,000 to 30,000. When the Mn of the AB block copolymer is less than 15,000, the durability of the formed image (dry film) may be somewhat inferior. On the other hand, if the Mn of the AB block copolymer exceeds 50,000, the viscosity of the ink may be excessively increased, or a large amount of polymer outside the above molecular weight range may be contained.

The AB block copolymer has a molecular weight distribution (PDI) of 1.6 or less, preferably 1.5 or less. If the AB block copolymer has a PDI of more than 1.6, it tends to contain a large amount of Mn outside the above range.

[Requirement (9)]
The AB block copolymer is particles (binder particles) having a number average particle size of 10 to 200 nm, preferably 50 to 150 nm. The number average particle size of particles such as polymer particles in the present specification is a value measured by a dynamic light scattering method. When AB block copolymers are mixed with water, the A2 chains form particles and the B2 chains dissolve in water to form binder particles, thus forming micelles, aqueous dispersions, or emulsions. Dissolution without particle formation can lead to an excessive increase in viscosity of the ink. In contrast, the AB block copolymer forms particles and does not excessively increase the viscosity of the ink. When the number average particle diameter of the binder particles formed by the AB block copolymer is less than 10 nm, the viscosity of the ink tends to increase because the binder particles are in a dissolved state. On the other hand, if the number average particle diameter of the binder particles exceeds 200 nm, the ejection performance from the nozzles of the inkjet head may slightly deteriorate.

Ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate are preferably used as methacrylates derived from biological materials. The binder component may be, for example, an ABC triblock structure, an ABCB tetrablock structure, a gradient structure, or the like. In the case of the ABC triblock structure, it may be an A-(BC) block structure in which the A chain is insoluble, the B chain is water soluble, and the C chain is water soluble. Furthermore, it may be an ABA block structure.

The above AB block copolymer used as a binder component can be produced according to a conventionally known method. For example, it can be produced by living anionic polymerization, living cationic polymerization, or living radical polymerization. Among them, living radical polymerization is preferable from the viewpoint of conditions, materials, equipment, and the like. In particular, the RTCP method and the RCMP method, which use an organic iodide as a starting compound and an organic compound as a catalyst, are advantageous in terms of cost because they do not require heavy metals or special compounds, and are easy to purify and process. It is also advantageous in terms of Further, solution polymerization in which the polymer is polymerized in a water-soluble organic solvent blended in the ink is preferable. By adding an alkali after solution polymerization, a particulate binder component can be obtained.

<Dry film>
The aqueous inkjet ink described above can be applied to an inkjet printer equipped with a recording head such as a thermal head or a piezo head, and can record (print) images on various printing substrates by an inkjet recording method. . Specifically, images can be recorded on printing substrates such as paper, photographic paper, photographic glossy paper, plastic films such as polyolefin and polyethylene terephthalate, fibers, fabrics, ceramics, metals and moldings. The recorded image is a so-called dry film that is excellent in durability such as high chroma, high color development, adhesion, and abrasion resistance. That is, by using the water-based inkjet ink of the present invention, it is possible to produce a dry film that is an environmentally friendly, carbon-neutral dried film that contains a component derived from a (meth)acrylate derived from a biological material.

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited by the following examples as long as the gist thereof is not exceeded. "Parts" and "%" regarding component amounts are based on mass unless otherwise specified.

<Production of polymer dispersant>
(Working Synthesis Example 1)
300 parts of diethylene glycol (BDG) was put into a reaction vessel equipped with a stirring device, a thermometer, a reflux tube, a dropping device and a nitrogen inlet tube while bubbling nitrogen, and heated to 70°C. In a separate container, 30 parts of isobornyl methacrylate (IBXMA), 120 parts of tetrahydrofurfuryl methacrylate (THFMA), 60 parts of lauryl methacrylate (LMA), 60 parts of 2-hydroxyethyl methacrylate (HEMA), 30 parts of methacrylic acid (MAA) , and 2,2′-azobis(2,4-dimethylvaleronitrile) (trade name “V-65”, manufactured by Fuji Film Co., Ltd., V-65) 2 parts are mixed and homogenized to form a monomer mixture. prepared. As the isobornyl methacrylate, methacrylate (biomass degree: 71.4%) obtained by isomerizing α-pinene obtained from pine resin or pine essential oil and then reacting with camphene and methacrylic acid was used. As the tetrahydrofurfuryl methacrylate, an ester of tetrahydrofurfuryl alcohol obtained by hydrogenating furfural obtained from corn cobs or the like and methacrylic acid (biomass degree 55.5%) was used. Lauryl methacrylate is an esterified product (biomass degree 75.0%) was used. After dropping 1/3 of the prepared monomer mixture into the reaction vessel, the remainder of the monomer mixture was added dropwise over 2 hours, polymerized at 70° C. for 8 hours to synthesize a polymer, and the polymer-containing liquid got A portion of the liquid was sampled, and the molecular weight of the polymer was measured by gel permeation chromatography (GPC) using tetrahydrofuran as a developing solvent. As a result, the number average molecular weight (Mn) of the polymer was 19,800, the molecular weight distribution (PDI = weight average molecular weight (Mw)/number average molecular weight (Mn)) was 2.01, and the polymerization rate was about 100%. Met. The rate of polymerization was calculated from the residue obtained by measuring a portion of the obtained liquid in an aluminum dish, drying it with a blower dryer at 150° C. for 3 hours.

A portion of the obtained liquid was sampled and homogenized by adding a toluene/ethanol (=1/1 (volume ratio)) mixed solvent. A few drops of a 1% phenolphthalein/ethanol solution were added, and titration was carried out with a 0.1 N potassium hydroxide ethanol solution to measure the acid value of the polymer. As a result, the acid value of the polymer was 64.9 mgKOH/g. A mixture of 13.9 parts of sodium hydroxide and 136.1 parts of water was added to the solution containing the polymer for neutralization to obtain an aqueous solution of dispersant D-1 (viscous pale yellow transparent liquid). . The resulting aqueous solution had a solids content of 42.1% and a pH of 10.1.

In the resulting dispersant D-1 (polymer), the content of structural units derived from biological material-derived methacrylate was 70%. In addition, the degree of biomass of the obtained polymer was calculated from the formula shown below.
Polymer biomass degree = (moles of each monomer in 100 parts of polymer x carbon number of each monomer x total biomass degree of each monomer) ÷ (moles of each monomer in 100 parts of polymer x total carbon number of each monomer)

In the case of dispersant D-1, the degree of biomass is (0.045 × 14 × 71.4% (IBXMA) + 0.235 × 9 × 55.5% (THFMA) + 0.078 × 16 × 75.0% ( LMA) + 0.154 x 6 x 0% (HEMA) + 0.116 x 4 x 0 (MAA)) ÷ (0.045 x 14 (IBXMA) + 0.235 x 9 (THFMA) + 0.078 x 16 (LMA) +0.154 x 6 (HEMA) + 0.116 x 4 (MAA)) = 2.56 ÷ 5.38 = "47.5%". The initiator shall not be used in calculating the degree of biomass since not all of its residues are incorporated into the polymer.

1,000 g of polymer contains 53.9 mol of carbon. The amount (mol) of carbon in 1,000 g of polymer can be calculated from each part by mass of monomers constituting the polymer, the molecular weight of the monomer, and the number of carbon atoms. Since the biomass degree of the polymer is 47.5%, 1,000 g of the polymer contains 25.6 mol of carbon derived from biological materials. Since 1,126 g of carbon dioxide is released when 1,000 g of this polymer burns, the absorbed carbon dioxide of this polymer is "1,126 (g/1,000 g)." When 1,000 g of this polymer is used to form a coating film (dry film), 1,126 g of carbon dioxide is stored, contributing to the reduction of carbon dioxide in the environment.

(Working Synthesis Examples 2-4, Comparative Synthesis Examples 1-3)
Dispersants D-2 to 4 and dispersants R-1 to 3 were dispersants D-2 to 4 and dispersants R-1 to 3 in the same manner as in Synthesis Example 1 described above, except that the various materials of the types and amounts (unit: parts) shown in Tables 1 and 2 were used. was obtained. Tables 1 and 2 show the physical properties of the obtained dispersant. The meanings of abbreviations in Tables 1 and 2 are shown below.
・MPG: propylene glycol monomethyl ether ・StMA: stearyl methacrylate (stearyl alcohol obtained by hydrogen reduction of oleic acid, which is a fatty acid fraction obtained by hydrolyzing oils such as palm kernel oil and coconut oil, and methacrylic Esterified product with acid (81.8% biomass content))
・ OA: Octyl acrylate (octanol obtained by hydrogen reduction of caprylic acid, which is a fraction of fatty acids obtained by hydrolyzing oils such as palm kernel oil and coconut oil, and esterified product of acrylic acid (biomass degree 72.7%))
・EMA: Ethyl methacrylate (an esterified product of ethanol obtained by decomposing starch or sugar and methacrylate (biomass degree 33.3%))
・Itaconic acid: A monomer having a carboxyl group obtained by fermenting starch, etc. (100% biomass content)
・St: Styrene (petroleum-derived material)
・MMA: Methyl methacrylate (petroleum-derived material)
・BA: Butyl acrylate (petroleum-derived material)
・2-EHMA: 2-ethylhexyl methacrylate (petroleum-derived material)
・AIBN: 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile)

In addition, evaluation criteria for "environmental friendliness" in Tables 1 and 2 are shown below.
○: The biomass degree is 40% or more, and the absorbed carbon dioxide is 1,000 g/1,000 g or more.
x: The degree of biomass is less than 40%, or the absorbed carbon dioxide is less than 1,000 g/1,000 g.

(Working Synthesis Example 5)
119.0 parts of tripropylene glycol monomethyl ether, 59.5 parts of propylene glycol monopropyl ether, 1.0 part of iodine, 2 , 2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (trade name "V-70", manufactured by Fujifilm Corporation, V-70) 3.6 parts, THFMA 57.1 parts, IBXMA 24.0 parts , 16.4 parts EMA, 21.5 parts MAA, and 0.02 parts N-iodosuccinimide (NIS). Heated to 42° C. under nitrogen flow and polymerized for 8 hours to form a polymer. The polymerization rate measured by sampling a part was about 100%. The polymer formed had a Mn of 8,900, a PDI of 1.49 and an acid number of 117.7 mg KOH/g.

A mixture of 10 parts of sodium hydroxide and 109 parts of water was added for neutralization to obtain an aqueous solution of Dispersion D-5 (pale yellow transparent low viscosity liquid). The resulting aqueous solution had a solids content of 25.3% and a pH of 10.2. This polymer is a polymer formed by living radical polymerization (reversible transfer catalyst polymerization, RTCP method) using iodine as a starting group and an organic compound that abstracts iodine to generate radicals as a catalyst, and has a relatively uniform molecular weight. there is In the resulting dispersant D-5 (polymer), the content of structural units derived from biological material-derived methacrylate was 81.9%. Dispersant D-5 (polymer) had a biomass degree of 45.6% and absorbed carbon dioxide of 1,124 g/1,000 g.

(Working Synthesis Example 6)
283.1 parts of BDG, 119.2 parts of THFMA, 2.0 parts of iodine, 3.6 parts of V-70, and 0.2 parts of NIS were added to a reaction vessel equipped with a stirring device, a thermometer, a reflux tube, a dropping device, and a nitrogen inlet tube. I put one in. The mixture was heated to 45° C. with nitrogen bubbling and polymerized for 4 hours to form the A chain (polymer). The Mn measured by sampling a part was 5,100, the PDI was 1.21, and the polymerization rate was about 100%. A mixture of 119 parts THFMA and 30.2 parts MAA was added and polymerized at 45° C. for 4 hours to form the B chain and give an AB block copolymer. The AB block copolymer had an Mn of 10,700, a PDI of 1.31, an acid value of 73.0 mg KOH/g, and a conversion of about 100%. In addition, the Mn of the B chain (Mn of the entire Mn--Mn of the A chain) was 5,600, and the acid value calculated from the compounding value considering the polymerization rate was 132 mgKOH/g. After cooling the polymerization solution to room temperature, a mixture of 23.4 parts of 28% aqueous ammonia and 118.5 parts of water was added for neutralization to obtain an aqueous solution of dispersant D-6 (light brown transparent liquid). rice field. The resulting aqueous solution had a solids content of 41.1% and a pH of 9.2. In the resulting dispersant D-6 (polymer), the content of structural units derived from biological material-derived methacrylate was 88.7%. Dispersant D-5 (polymer) had a biomass degree of 49.9% and absorbed carbon dioxide of 1,145 g/1,000 g.

(Working Synthesis Examples 7 to 13)
Aqueous solutions of dispersants D-7 to D-13 were obtained in the same manner as in Synthesis Example 6 described above, except that the types and amounts (unit: parts) of various materials shown in Table 3 were used. Table 3 shows the physical properties of the obtained dispersant. Moreover, in Table 3, "DMEA" is dimethylaminoethanol.

<Preparation of pigment dispersion>
(Example 1)
89.1 parts of an aqueous solution of dispersant D-1 and 337.8 parts of ion-exchanged water were mixed to obtain a transparent liquid. 150 parts of a copper phthalocyanine pigment PB-15:3 (trade name “Cyanine Blue A220JC”, manufactured by Dainichiseika Kogyo Co., Ltd.) was added to the resulting solution and stirred for 30 minutes using a disper to prepare a millbase. Using a horizontal medium dispersing machine (trade name “Dyno Mill 0.6 liter ECM type”, manufactured by Shinmaru Enterprises, zirconia bead diameter: 0.5 mm), disperse at a peripheral speed of 10 m / s and in the mill base The pigment was sufficiently dispersed in the 256.4 parts of water was added to adjust the pigment concentration to 18%. The millbase was centrifuged (7,500 rpm, 20 minutes) and then filtered through a membrane filter with a pore size of 5 µm. By diluting with water, an inkjet pigment dispersion-1 (cyan color) having a pigment concentration of 14% was obtained.

The number average particle diameter of the pigment in the pigment dispersion liquid-1 measured using a particle size analyzer (trade name “NICOMP 380ZLS-S”, manufactured by International Business Co., Ltd.) was 138.5 nm, and the pigment was finely dispersed. I confirmed that Further, the viscosity of Pigment Dispersion-1 was 3.70 mPa·s and the pH was 9.4. The viscosity of Pigment Dispersion-1 is a value at 25° C. measured at 60 rotations using an E-type viscometer. After being stored at 70° C. for one week, the number average particle diameter of the pigment in Pigment Dispersion-1 was 138.5 nm, and the viscosity was 3.66 mPa·s. From this, it was confirmed that the storage stability of Pigment Dispersion-1 was very good.

(Examples 2 to 13, Comparative Examples 1 to 3)
Pigment Dispersions-2 to 13 and Pigment Dispersions-1H to 3H were prepared in the same manner as in Example 1 except that the types of dispersants shown in Table 4 were used. Table 4 shows the properties of each pigment dispersion (the number average particle size and viscosity of the pigment immediately after dispersion and after storage at 70° C. for one week).

In addition, the criteria for "evaluation" in Table 4 are shown below.
◯: The pigment was finely dispersed, and the number average particle size and viscosity of the pigment did not change significantly even after storage at 70° C. for 1 week.
Δ: The pigment was finely dispersed, but the viscosity was higher than 4 mPa·s. Moreover, the number average particle size and viscosity of the pigment hardly changed even after storage at 70° C. for one week.
x: The pigment was finely dispersed, but after storage at 70°C for 1 week, the number average particle size of the pigment increased or the viscosity increased.

(Examples 14-16)
Instead of copper phthalocyanine pigment PB-15:3, azo yellow pigment PY-155 (trade name “VERSAL YELLOW 4GNY”, Clariant Japan Co., Ltd.), quinacridone pigment PR-122 (trade name “CFR130P”, Dainichiseika Kogyo Pigment Dispersions-14 to 16 were obtained in the same manner as in Example 10 described above, except that a carbon black pigment PB-7 (trade name “S170”, manufactured by Deguza) was used. . Table 5 shows the properties of each pigment dispersion (the number average particle size and viscosity of the pigment immediately after dispersion and after storage at 70° C. for one week).

(Example 17)
401.2 parts of water and 98.8 parts of an aqueous solution of dispersant D-5 were mixed and homogenized to obtain a liquid. C.I. I. Pigment White 6 (trade name “JR-404”, manufactured by Ishihara Sangyo Co., Ltd.) was added in 500 parts. A dissolver was used to thoroughly stir and mix to obtain a mixture containing pigment and dispersant. After sufficiently dispersing the pigment in the mixture using a horizontal medium dispersing machine, coarse particles are removed by filtration through a membrane filter with a pore size of 10 μm, and a pigment dispersion for inkjet-17 (pigment concentration of 50%) ( white color) was obtained. The pigment in Pigment Dispersion-17 had a number average particle diameter of 263.7 nm and a viscosity of 12.6 mPa·s. After being stored at 70° C. for one week, the number average particle diameter of the pigment in Pigment Dispersion Liquid-17 was 226.4 nm, and the viscosity was 12.8 mPa·s.

<Preparation of ink (1)>
(Examples 18-27, Comparative Examples 4-6)
28.7 parts of pigment dispersion of the type shown in Table 6, 1.5 parts of BDG, 5 parts of 2-pyrrolidone, 20.0 parts of glycerin, 1 part of surfactant (trade name "Surfinol 465", manufactured by Air Products) , and 44.8 parts of water were mixed, thoroughly stirred, and filtered through a membrane filter with a pore size of 10 μm to prepare an inkjet ink. Table 6 shows the properties of each ink (number average particle size and viscosity of the pigment immediately after preparation and after storage at 70° C. for 1 week). In addition, the criteria for "evaluation" in Table 6 are shown below.
◯: The number average particle size and viscosity of the pigment did not change significantly even after storage at 70° C. for 1 week.
Δ: Even after storage at 70° C. for 1 week, the number average particle size of the pigment did not change significantly, but the viscosity increased.
x: The pigment was finely dispersed, but after storage at 70°C for 1 week, the number average particle size of the pigment increased or the viscosity increased.

<Evaluation of Ink (1)>
(Practical application examples 1 to 4)
Each of the inks obtained in Examples 23 and 25 to 27 was filled in a cartridge and installed in an inkjet printer (trade name “EM930C”, manufactured by Seiko Epson Corporation). Solid images were printed on (i) exclusive photo glossy paper (PGPP) and (ii) plain paper (trade name “4024”, manufactured by Xerox) in the “Photo 720 dpi” print mode to obtain prints. It was confirmed that any ink could be ejected from an inkjet nozzle without any problem.

Using an optical densitometer (trade name "Macbeth RD-914", manufactured by Macbeth), the chroma (C ^* ), optical density (OD value), and 20° gloss of the image recorded on PGPP, and on plain paper The optical density (OD value) of the recorded image was measured. Table 7 shows the results. Each characteristic value was measured five times, and the average value was calculated. Also, the surface of the image recorded on the PGPP was rubbed with a finger to evaluate the abrasion resistance of the image. Table 7 shows the results.

The inks obtained in other Examples were also tested in the same manner as described above, and it was confirmed that the inks could be ejected from nozzles without problems and that images with high color development and abrasion resistance could be recorded.

<Preparation of binder component>
(Working Synthesis Example 14)
360.2 parts of BDG, 124.3 parts of THFMA, 50.5 parts of IBXMA, 1.5 parts of iodine, 5.5 parts of V-70 were added to a reaction vessel equipped with a stirring device, a thermometer, a reflux tube, a dropping device, and a nitrogen inlet tube. and 0.3 parts of NIS. The mixture was heated to 45° C. with nitrogen bubbling and polymerized for 4 hours to form the A chain (polymer). The Mn measured by sampling a part was 10,200, the PDI was 1.29, and the polymerization rate was about 100%. A mixture of 86.8 parts THFMA and 22.6 parts MAA was added and polymerized at 45° C. for 4 hours to form the B chain and yield an AB block copolymer. The AB block copolymer had an Mn of 16,000, a PDI of 1.38, an acid number of 51.5 mg KOH/g, and a conversion of about 100%. In addition, the Mn of the B chain (Mn of the entire Mn-A chain) was 5,800, and the acid value calculated from the compounding value considering the polymerization rate was 116.4 mgKOH/g. After the polymerization solution was cooled to room temperature, a mixture of 17.5 parts of 28% aqueous ammonia and 310 parts of water was added for neutralization to obtain a liquid (brown transparent liquid) containing binder B-1. The resulting liquid had a solids content of 30.8% and a pH of 8.5. In the resulting binder B-1 (polymer), the content of structural units derived from biological material-derived methacrylate was 92.1%. Further, the biomass degree of binder B-1 (polymer) was 55.1%, and the absorbed carbon dioxide was 1,313 g/1,000 g. A sample was prepared by diluting a liquid containing Binder B-1 10 times with pure water. The number average particle size of the emulsion particles in the sample measured using a particle size distribution analyzer was 48.6 nm.

(Working Synthesis Examples 15-19)
Liquids containing binders B-2 to B-6 were obtained in the same manner as in Synthetic Example 14 except that the types and amounts (unit: parts) of various materials shown in Table 8 were used. Table 8 shows the physical properties of the obtained binder component.

<Preparation of ink (2)>
(Examples 28-35)
Pigment Dispersion-10 prepared in Example 10, Binder Components B-1 to -6 prepared in Synthesis Examples 14 to 19, and Binders B-7 and B-8 shown below were prepared.

[Binder B-7: Urethane Water Dispersion]
Petroleum material-derived binder component obtained by neutralizing polyurethane composed of isophorone diisocyanate/polyhexamethylene carbonate diol/dimethylolbutanoic acid/hydrazine with triethylamine Acid value 34.2 mg KOH/g, number average particle diameter 42.2 nm, solid content 25 %

[Binder B-8: styrene acrylic emulsion]
Protection obtained by polymerizing styrene and butyl acrylate using a protective colloid of ammonia-neutralized styrene/acrylic acid/methoxyethyl acrylate copolymer having an Mn of 3,000 and an acid value of 260 mgKOH/g. Colloidal emulsion (binder component derived from petroleum materials)
Styrene/acrylic acid/methoxyethyl acrylate copolymer/styrene/butyl acrylate = 30/30/40 (mass ratio), number average particle size 105 nm, solid content 43%

In 100 parts of ink, pigment dispersion liquid-10 in an amount such that the pigment content is 4 parts, binder (solid content) 4 parts, surfactant (Surfinol S465) 0.1 part, wax (ethylene acrylic acid Ionomer, trade name "Chemipearl W300", manufactured by Mitsui Chemicals, Inc.) 0.7 parts, propylene glycol 12.0 parts, and water (the balance) were mixed to obtain a mixture of each component, and after sufficiently stirring, a membrane having a pore size of 10 μm was prepared. After filtration through a filter, an ink for inkjet was prepared. Table 9 shows the properties of each ink (number average particle size and viscosity of the pigment immediately after preparation and after storage at 70° C. for 1 week). In addition, the criteria for "evaluation" in Table 9 are shown below.
◯: The number average particle size and viscosity of the pigment did not change significantly even after storage at 70° C. for 1 week.
Δ: Even after storage at 70° C. for 1 week, the number average particle size of the pigment did not change significantly, but the viscosity increased.
x: The pigment was finely dispersed, but after storage at 70°C for 1 week, the number average particle size of the pigment increased or the viscosity increased.

(Examples 36-39)
Ink jet inks were prepared in the same manner as in Example 30 except that Pigment Dispersion-14 to 16 were used instead of Pigment Dispersion-10 (Examples 36 to 38). Pigment Dispersion Liquid-17 was used in the same manner as in Example 28 described above, and Pigment Dispersion Liquid-17 and Binder B-1 (solid content ), 0.1 part of a surfactant (Surfinol S465), 12.0 parts of propylene glycol, and water (the balance) to prepare an inkjet ink (Example 39 ). Table 10 shows the properties of each ink (number average particle size and viscosity of the pigment immediately after preparation and after storage at 70° C. for 1 week). In addition, the criteria for "evaluation" in Table 10 are shown below.
◯: The number average particle size and viscosity of the pigment did not change significantly even after storage at 70° C. for 1 week.
Δ: Even after storage at 70° C. for 1 week, the number average particle size of the pigment did not change significantly, but the viscosity increased.
x: The pigment was finely dispersed, but after storage at 70°C for 1 week, the number average particle size of the pigment increased or the viscosity increased.

<Evaluation of Ink (2)>
(Practical application examples 5 to 22)
Each of the inks obtained in Examples 28 to 39 was filled in a cartridge and installed in an inkjet printer with a plate heater (trade name "MMP825H", manufactured by Mastermind). Then, an image was printed on each printing substrate heated by a plate heater so that the surface temperature was 50° C. to obtain a printed material. The printing substrates used are shown below.
・Polyvinyl chloride film (manufactured by 3M, 30 μm)
・ OPP film (polypropylene film, manufactured by Futamura Chemical Co., Ltd., 50 μm)
・ PET film (polyethylene terephthalate film, (manufactured by Futamura Chemical Co., Ltd., 60 μm)

(Ejectability)
The ejection state of the ink during printing was visually observed, and the ejection properties of the ink were evaluated according to the evaluation criteria shown below. Table 11 shows the results.
Good: Ejection was possible without problems, and a good image was printed.
Δ: Scattering of microdroplets was observed.
x: During ejection, the droplets were splashed and scattered, and the image was disturbed.

(Adhesion)
After sufficiently drying the printed material using a dryer, the cellophane tape was sufficiently pressed against the image and peeled off. The degree of peeling of the image from the film was visually observed, and the adhesion of the image was evaluated according to the following evaluation criteria. Table 11 shows the results.
(double-circle): It did not peel at all.
O: Slightly peeled off.
Δ: The peeled area was smaller than the unpeeled area.
x: The peeled area was larger than the unpeeled area.

(Friction resistance (dry friction resistance and wet friction resistance))
Using a Gakushin type rubbing fastness tester (trade name "RT-300", manufactured by Daiei Kagaku Co., Ltd.), a dry white cloth and a white cloth moistened with water are applied to the surface of the image with a weight of 500 g each. A friction test was performed. The degree of peeling of the image after the rubbing test was visually observed, and the rubbing resistance (dry rubbing property and wet rubbing property) of the image was evaluated according to the evaluation criteria shown below. Table 11 shows the results.
(double-circle): It did not peel at all.
◯: Slightly peeled off.
Δ: The peeled area was smaller than the unpeeled area.
x: The peeled area was larger than the unpeeled area.

By using the aqueous pigment dispersion of the present invention, the pigment is stably and highly finely dispersed, and it is possible to record an image with excellent durability, glossiness, color development, and adhesion to various printing substrates. Moreover, it is possible to provide an environment-friendly water-based inkjet ink. This water-based inkjet ink is suitable for outdoor use display printing and high-volume high-speed inkjet printing, and is also useful as water-based flexographic printing ink, water-based paint, and water-based writing ink.

Claims (4)

A binder component that is a polymer that satisfies the following requirements (5) to (9).
[Requirement (5)]:
It is an AB block copolymer containing a polymer chain A2 and a polymer chain B2 in which the content of structural units derived from methacrylic acid-based monomers is 90% by mass or more.
[Requirement (6)]:
The polymer chain A2 is
Containing 80% by mass or more of structural units derived from methacrylates derived from biological materials,
a number average molecular weight of 10,000 to 30,000,
It is a water-insoluble polymer block having a molecular weight distribution of 1.6 or less.
[Requirement (7)]:
The polymer chain B2 is
Containing structural units derived from methacrylic acid,
Containing 40 to 90% by mass of structural units derived from methacrylates derived from biological materials,
an acid value of 50 to 150 mgKOH/g,
a number average molecular weight of 5,000 to 20,000,
It is a polymer block in which at least a portion of the carboxy groups are neutralized with alkali.
[Requirement (8)]:
It has a number average molecular weight of 15,000 to 50,000 and a molecular weight distribution of 1.6 or less.
[Requirement (9)]:
The particles have a number average particle diameter of 10 to 200 nm. 2. The binder component according to claim 1, wherein the biological material-derived methacrylate is at least one selected from the group consisting of ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate. 3. The binder component according to claim 1, which is used in aqueous inkjet inks. An emulsion containing water and binder particles formed from the binder component according to any one of claims 1 to 3.