JP2021070751A - Oil-based inkjet ink, method for producing oil-based inkjet ink and method for producing dispersant - Google Patents

Abstract

To provide an oil-based inkjet ink that has less tendency for aggregation.SOLUTION: An oil-based inkjet ink contains: a pigment; a dispersant formed of an acidic resin, a low molecular amine compound, and a (meth)acrylic resin having at least one group selected from a group consisting of a group represented by a general formula (1) and a group represented by a general formula (2); and a non-aqueous solvent. In the general formula (1), R1 and R2 independently represent a hydrogen atom or a substituent, and R1 and R2 may be bound to form a ring. In the general formula (2), R3 is a substituent, R4 is a hydrogen atom or a substituent, and R3 and R4 may be bound to form a ring.SELECTED DRAWING: None

Description

An embodiment of the present invention relates to an oil-based inkjet ink, a method for producing an oil-based inkjet ink, and a method for producing a dispersant.

The inkjet recording method injects highly fluid inkjet ink as droplets from a fine nozzle and records an image on a recording medium placed facing the nozzle, enabling high-speed printing with low noise. Therefore, it has spread rapidly in recent years. As inks used in such an inkjet recording method, water-based inks containing water as a main solvent, ultraviolet curable inks (UV inks) containing a high content of polymerizable monomers as main components, and wax as main components are high. A so-called non-aqueous ink containing a non-aqueous solvent as a main solvent is known as well as a hot melt ink (solid ink) contained in a content. Non-aqueous inks can be classified into solvent inks (solvent-based inks) in which the main solvent is a volatile organic solvent and oil-based inks (oil-based inks) in which the main solvent is a low-volatile or non-volatile organic solvent. The solvent ink dries on the recording medium mainly by evaporation of the organic solvent, whereas the oil-based ink dries mainly by penetrating into the recording medium.

Patent Document 1 discloses a colored resin particle dispersion containing colored resin particles containing a phosphate esterified solid resin and / or a nitrate esterified solid resin, and an inkjet ink containing the same.
Patent Document 2 discloses a colored resin particle dispersion containing colored resin particles containing a solid resin and a liquid organic compound having an acidic group, and an inkjet ink containing the same.
Patent Document 3 includes an encapsulating pigment containing a urethane compound and a non-aqueous solvent. The urethane compound has a side chain containing a urethane skeleton, a carboxy group, and the like, and is insoluble in the non-aqueous solvent. Oil-based inkjet inks are disclosed.

Japanese Unexamined Patent Publication No. 2015-134850 Japanese Unexamined Patent Publication No. 2015-134852 Japanese Unexamined Patent Publication No. 2018-48293

Aggregates may be generated when the ink receives an external force, such as when the ink in the ink path is slid by a liquid feed pump.
An object of the present invention is to provide an oil-based inkjet ink that does not easily form agglomerates.

One embodiment of the present invention is selected from the group consisting of a pigment, an acidic resin, a low molecular weight amine compound, and a group represented by the following general formula (1) and a group represented by the following general formula (2). The present invention relates to an oil-based inkjet ink containing a dispersant formed of a (meth) acrylic resin containing at least one group and a non-aqueous solvent.

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring. In the general formula (2), R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.

（一般式（１）において、Ｒ^１及びＲ^２はそれぞれ独立に水素原子又は置換基を表し、Ｒ^１とＲ^２とは互いに結合して環を形成していてもよい。一般式（２）において、Ｒ^３は置換基を表し、Ｒ^４は水素原子又は置換基を表し、Ｒ^３とＲ^４とは互いに結合して環を形成していてもよい。） Other embodiments of the present invention include a non-aqueous solvent and at least one group selected from the group consisting of a group represented by the following general formula (1) and a group represented by the following general formula (2). A step of obtaining a water-in-oil emulsion containing a continuous phase containing a (meth) acrylic resin and a dispersed phase containing water, an acidic water-dispersible resin and a low-molecular-weight amine compound, and water from the water-in-oil emulsion. The present invention relates to a method for producing an oil-based inkjet ink, which comprises a step of removing and obtaining a dispersant dispersion and a step of mixing the dispersant dispersion and a pigment and dispersing the pigment.

(In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring. General formula (2) In, R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.)

Other embodiments of the present invention include a non-aqueous solvent and at least one group selected from the group consisting of a group represented by the following general formula (1) and a group represented by the following general formula (2). A step of obtaining a water-in-oil emulsion containing a continuous phase containing a (meth) acrylic resin and a dispersed phase containing water, an acidic water-dispersible resin and a low-molecular-weight amine compound, and water from the water-in-oil emulsion. The present invention relates to a method for producing a dispersant, which comprises a step of removing.

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring. In the general formula (2), R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.

According to the embodiment of the present invention, it is possible to provide an oil-based inkjet ink that does not easily generate agglomerates.

Hereinafter, embodiments of the present invention will be described, but the following embodiments do not limit the present invention.
Hereinafter, the oil-based inkjet ink may be referred to as "ink" or "oil-based ink".

The oil-based inkjet ink according to the embodiment of the present invention is a group consisting of a pigment, an acidic resin, a low molecular weight amine compound, a group represented by the following general formula (1), and a group represented by the following general formula (2). An oil-based inkjet ink containing a dispersant (hereinafter, may be simply referred to as “dispersant”) formed of a (meth) acrylic resin containing at least one group selected from the above, and a non-aqueous solvent. ..

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring. In the general formula (2), R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.
Hereinafter, the (meth) acrylic resin containing at least one group selected from the group consisting of the group represented by the following general formula (1) and the group represented by the following general formula (2) is referred to as "(meth). It may be called "acrylic resin A".

In ink, when a compound having a free acidic group is present around the pigment, the cohesive force of the pigment tends to increase, and such an ink tends to generate agglomerates when it receives an external force such as sliding. Tend. The oil-based inkjet ink of the present embodiment uses a dispersant formed of an acidic resin, a low-molecular-weight amine compound, and a (meth) acrylic resin A, so that it is an agglomerate even when it receives an external force such as sliding. Can be used as an ink that does not easily generate. Although not bound by a specific theory, the reason for this is that in this dispersant, the basic group of the low molecular weight amine compound is bonded to the acidic group of the acidic resin, or it is represented by the general formula (1). At least one group selected from the group consisting of the groups to be subjected to and the groups represented by the general formula (2) has an affinity with the acidic group, thereby reducing the amount of free acidic groups and making it difficult for the pigment to aggregate. It is presumed that this is because it can be done.

The method for producing the oil-based inkjet ink of the present embodiment is not particularly limited, and for example, it can be produced by a method using a method for drying a water-in-oil (W / O) emulsion in oil, which will be described later.

The oil-based inkjet ink can contain pigments.

As the pigment, organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments and dyed lake pigments, and inorganic pigments such as carbon black and metal oxides can be used.
Examples of the azo pigment include soluble azo lake pigments, insoluble azo pigments and condensed azo pigments. Examples of the phthalocyanine pigment include metal phthalocyanine pigments and non-metal phthalocyanine pigments. Polycyclic pigments include quinacridone pigments, perylene pigments, perinone pigments, isoindolin pigments, isoindolinone pigments, dioxazine pigments, thioindigo pigments, anthracinone pigments, quinophthalone pigments, and metal complex pigments. And diketopyrrolopyrrole (DPP) and the like. Examples of carbon black include furnace carbon black, lamp black, acetylene black, and channel black. Examples of the metal oxide include titanium oxide and zinc oxide. These pigments may be used alone or in combination of two or more.
From the viewpoint of obtaining a highly saturated printed matter, the cyan ink preferably contains copper phthalocyanine blue. The yellow ink preferably contains any one of monoazo yellow, disazo yellow, and benzimidazolone yellow, and more preferably contains disazo yellow. The magenta ink preferably contains any one of azolake red, naphthol AS, benzimidazolone red, and quinacridone magenta, and more preferably contains azolake red.

The dispersed form of the pigment may be, for example, a form in which colored resin particles containing the pigment and the dispersant are formed and the colored resin particles are dispersed. The colored resin particles containing the pigment and the dispersant may be, for example, a so-called capsule pigment in which the pigment is coated with the dispersant.

The average particle size of the pigment is preferably 300 nm or less, more preferably 200 nm or less, from the viewpoint of discharge stability and storage stability.
The pigment is usually 0.01 to 20% by mass with respect to the total amount of ink, and is preferably 1 to 15% by mass from the viewpoint of image density and ink viscosity.

The oil-based inkjet ink can contain a dispersant formed of an acidic resin, a low molecular weight amine compound, and a (meth) acrylic resin A. The dispersant may be formed by using at least an acidic resin, a low molecular weight amine compound, and a (meth) acrylic resin A, and is an acidic resin, a low molecular weight amine compound, and a (meth) acrylic resin A. In addition to, other components may be further used to form.
The dispersant is preferably used in the form of resin particles in the manufacturing process of the oil-based inkjet ink. For example, when the dispersant is produced by a method using a method of drying a water-in-oil (W / O) emulsion in oil, the dispersant can be produced preferably in the form of resin particles.
In the oil-based inkjet ink, for example, it is preferable that the dispersant and the pigment are contained in the colored resin particles. Examples of such colored resin particles include those in which the pigment is coated with a dispersant.

The acidic resin is not particularly limited, and is, for example, an acidic urethane resin, an acidic polyester resin, an acidic (meth) acrylic resin, an acidic urethane (meth) acrylic resin, an acidic (meth) acrylic silicone resin, and an acidic vinyl chloride. Examples thereof include based resins and acidic styrene (meth) acrylic resins. As the acidic resin, an acidic urethane resin and an acidic (meth) acrylic resin are preferable, and an acidic urethane resin is more preferable, from the viewpoint of improving scratch resistance.

Urethane-based resins have a urethane group. Generally, the urethane group of a urethane-based resin can be obtained by reacting a polyol with a polyisocyanate, but the acidic urethane-based resin preferably uses an aliphatic polyisocyanate as the polyisocyanate from the viewpoint of storage stability.

As the acidic urethane resin, an acidic urethane urea resin having a urea group in addition to the urethane group is preferable from the viewpoint of improving scratch resistance. The urethane urea-based resin is prepared by reacting a urethane prepolymer obtained from a material containing a polyol and a polyisocyanate with water and / or a polyamine compound to cause the isocyanate group of the urethane prepolymer and the water and / or polyamine compound. Can be obtained by forming a urethane group by reacting with and extending the chain.

Examples of acidic urethane-based resins also include acidic urethane (meth) acrylic resins, which are also included in the examples of acidic (meth) acrylic resins.
(Meta) acrylic means methacrylic, acrylic, or a combination thereof, and (meth) acrylic resin includes a resin containing a methacrylic unit, a resin containing an acrylic unit, or a resin containing both of these units. means.

The acidic resin may be a resin having an acidic group, or an acidic water-dispersible resin may be used as a raw material in the production of ink. As the acidic resin, a resin having an acidic group is preferable, and as the acidic group, a carboxy group, a sulfo group, a phosphoric acid group and the like are preferable.

The acidic resin is preferably a resin that is solid at 23 ° C.
From the viewpoint of reducing strike-through and improving the image density of the acidic resin, the solubility of the ink in the non-aqueous solvent is 1 g or less as the amount of the resin that can be dissolved in 100 g of the non-aqueous solvent of the ink at 23 ° C. It is preferable to have. Furthermore, since the acidic resin is difficult to dissolve in the non-aqueous solvent, it can contribute to lowering the viscosity of the ink.

The weight average molecular weight of the acidic resin varies depending on the type of resin, but is preferably 5,000 to 200,000, more preferably 10,000 to 150,000, for example. For example, the weight average molecular weight of the acidic urethane resin is preferably 5,000 to 50,000, more preferably 10,000 to 30,000. The weight average molecular weight of the acidic (meth) acrylic resin is preferably 10,000 to 200,000, more preferably 30,000 to 150,000.
The weight average molecular weight of the resin is a value obtained by the GPC method in terms of standard polystyrene. The same applies to the weight average molecular weight of the resins described below.

For example, when a dispersant is produced by a method using a water-in-oil (W / O) emulsion drying method in oil, it is preferable to use an acidic water-dispersible resin in order to obtain an acidic resin. The acidic water-dispersible resin is preferably added in the form of a dispersion (oil-in-water type (O / W) resin emulsion) pre-dispersed in a liquid such as water in the production of ink. When an aqueous dispersion is used, it is preferable that the water contained in the aqueous dispersion is removed in the ink manufacturing process.

The acidic water-dispersible resin may be one in which the acidic group of the resin is present on the particle surface, such as a self-emulsifying resin, or one in which the surface of the resin particles is surface-treated such as attaching an acidic dispersant. Good. The acidic resin may be obtained from any of these. The acidic group is typically a carboxy group, a sulfo group, a phosphoric acid group or the like. Acidic dispersants are anionic surfactants and the like.

The method for synthesizing the acidic urethane resin is not particularly limited. The acidic urethane resin can be obtained, for example, by reacting a polyol with a polyisocyanate.
Examples of the polyol include polytetramethylene glycol, 2,2-dimethylolbutanoic acid, 1,4-butanediol, diethanolamine and the like. Further, as the polyol, for example, a diol obtained by Michael addition reaction of a dialkanolamine such as diethanolamine and a compound having an acryloyloxy group such as acrylic acid may be used. These polyols can be used alone or in combination of two or more. It is preferable that at least one of the polyols used has an acidic group.
As the polyisocyanate, for example, a diisocyanate such as hexamethylene diisocyanate can be used. One type of polyisocyanate can be used alone, or two or more types can be used in combination.

The acidic urethane urea resin can be obtained, for example, by reacting a polyol with a polyisocyanate to obtain a urethane prepolymer, and then reacting the obtained urethane prepolymer with water and / or a polyamine compound. The polyol and polyisocyanate are as described above. As the polyamine compound, for example, hexanediamine or the like can be used.

The method for synthesizing the acidic (meth) acrylic resin is not particularly limited. For example, it can be obtained by polymerizing with one or more monomers such as (meth) acrylic acid ester such as alkyl (meth) acrylate and (meth) acrylic acid. It is preferable that at least one of the monomers used in the synthesis of the acidic (meth) acrylic resin has an acidic group.

The aqueous dispersion of an acidic water-dispersible resin is one in which the resin is dispersed in water such as ion-exchanged water. When the resin is dispersed in water to produce an aqueous dispersion, a low-molecular-weight amine compound described later is used. Is preferably added. A low molecular weight amine compound may be added to an aqueous dispersion of a commercially available acidic aqueous dispersible resin.

Commercially available products of the aqueous dispersion of acidic water-dispersible urethane resin include, for example, "WS5984" (trade name) and "WS4022" (trade name) manufactured by Mitsui Chemicals Co., Ltd. and "Superflex" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. 740 "(product name)," Superflex 150H "(product name)," U-coat UWS-145 "(product name) manufactured by Sanyo Kasei Kogyo Co., Ltd.," DAOTAN TW-6493 "(product name) manufactured by Daicel Ornex Co., Ltd. , "DAOTAN TW-6490" (trade name) and the like.
Examples of commercially available products of aqueous dispersions of acidic water-dispersible urethane (meth) acrylic resins include "DAOTAN VTW-1262" (trade name) manufactured by Daicel Ornex Co., Ltd.
Urethane type of "WS5984", "WS4022", "Superflex 740", "Superflex 150H", "Ucourt UWS-145", "DAOTAN TW-6493", "DAOTAN TW-6490", "DAOTAN VTW-1262" The resin is a urethane urea-based resin having a urea group.
Examples of commercially available products of the aqueous dispersion of the acidic water-dispersible (meth) acrylic resin include "Movinyl 6750" (trade name) and "Movinyl 6969D" (trade name) manufactured by Japan Coating Resin Co., Ltd.

As the dispersant, one type of acidic resin may be used alone, or two or more types may be used in combination.

As the low molecular weight amine compound, an amine compound having a molecular weight of 1000 or less is preferable, an amine compound having a molecular weight of 700 or less is more preferable, an amine compound having a molecular weight of 400 or less is more preferable, and an amine compound having a molecular weight of 300 or less is further preferable.
The low molecular weight amine compound preferably has no repeating unit.
The molecular weight of the low molecular weight amine compound is a (meth) acrylic resin containing at least one group selected from the group consisting of a group represented by the general formula (1) and a group represented by the general formula (2). It is preferably smaller than the weight average molecular weight of the meta) acrylic resin A).

As the low molecular weight amine compound, ammonia, a primary amine compound, a secondary amine compound, a tertiary amine compound and the like can be used.
Examples of the primary amine compound include monomethylamine, monoethylamine, monobutylamine, monoethanolamine and the like.
Examples of the secondary amine compound include dimethylamine, diethylamine, dibutylamine, diethanolamine, diisopropanolamine, methylpropanolamine and the like.
Examples of the tertiary amine compound include trialkylamines such as trialkylamines having an alkyl group having 1 to 4 carbon atoms, such as trimethylamine, triethylamine, and dimethylethylamine; dimethylethanolamine, methyldiethanolamine, and triethanolamine. , Alkanolamines such as triisopropanolamine; heterocyclic amines such as morpholin compounds such as N-substituted morpholin compounds exemplified by N-alkylmorpholin and the like can be used.

From the viewpoint of making it difficult for aggregates to form over a long period of time, the low molecular weight amine compound preferably has low volatility. From this viewpoint, as the low molecular weight amine compound, alkanolamines such as monoethanolamine, diethanolamine, diisopropanolamine, methylpropanolamine, dimethylethanolamine, methyldiethanolamine, triethanolamine and triisopropanolamine are preferable.

As the dispersant, a low molecular weight amine compound may be used alone or in combination of two or more.

The (meth) acrylic resin ((meth) acrylic resin A) containing at least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2) , The group represented by the general formula (1), the group represented by the general formula (2), or both of them may be included. The (meth) acrylic resin A may be, for example, either a homopolymer or a copolymer, and is preferably a copolymer.

The weight average molecular weight of the (meth) acrylic resin A is preferably 5,000 or more, more preferably 7,000 or more. The weight average molecular weight of the (meth) acrylic resin A is preferably 50,000 or less, more preferably 30,000 or less.
The weight average molecular weight of the (meth) acrylic resin A is preferably, for example, 5,000 to 50,000, more preferably 7,000 to 30,000.

The (meth) acrylic resin A is preferably dissolved in a non-aqueous solvent contained in the ink. Specifically, the (meth) acrylic resin A and the non-aqueous solvent contained in the ink are mixed at 20 ° C. at 1 atm. When mixed in the same volume, it is preferable that the mixture is uniformly dissolved without being divided into two phases.

The (meth) acrylic resin A preferably contains at least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2).

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring.

In the general formula (1), R ¹ and R ² each independently represent a hydrocarbon atom or a hydrocarbon group which may have a substituent, or R ¹ and R ² are bonded to each other. It is preferable that a ring is formed.

Examples of the hydrocarbon group include an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group and an alkynyl group, which may be a straight chain or a branched chain. The hydrocarbon group preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. As the hydrocarbon group, an alkyl group is preferable, an alkyl group having 1 to 8 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. Specific examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group and the like. For example, R ¹ and R ² are preferably alkyl groups having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, which may independently have a hydrogen atom or a substituent. Good.

When R ¹ and R ² are bonded to each other to form a ring, a 3- to 8-membered ring is preferable, a 5- to 7-membered ring is more preferable, and a 4- to 6-membered ring is further preferable. Examples of the ring formed by bonding R ¹ and R ² to each other include a heterocycle containing a nitrogen atom as a hetero atom, a hetero ring containing a nitrogen atom and an oxygen atom as a hetero atom, and the like. Examples of the ring formed by bonding R ¹ and R ² to each other include morpholine, piperidine, pyrrolidine, etc., which may have a substituent.

In the general formula (2), R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.

In the general formula (2), ^{does R 3} represent a hydrocarbon group which may have a substituent and R ⁴ represents a hydrogen atom or a hydrocarbon group which may have a substituent? Or, ^{it is preferable that R 3} and R ⁴ are bonded to each other to form a ring.

Examples of the hydrocarbon group include an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group and an alkynyl group, which may be a straight chain or a branched chain. The hydrocarbon group preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. As the hydrocarbon group, an alkyl group is preferable, an alkyl group having 1 to 8 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. Specific examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group and the like. For example, R ³ may preferably be an alkyl group having 1 to 8 carbon atoms which may have a substituent, more preferably an alkyl group having 1 to 4 carbon atoms, and R ⁴ is preferably a hydrogen atom. Alternatively, it may be an alkyl group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, which may have a substituent.

When R ³ and R ⁴ are bonded to each other to form a ring, a 3- to 8-membered ring is preferable, a 5- to 7-membered ring is more preferable, and a 4- to 6-membered ring is further preferable. Examples of the ring formed by bonding R ³ and R ⁴ to each other include a heterocycle containing a nitrogen atom as a heteroatom, a heterocycle containing a nitrogen atom and an oxygen atom as a heteroatom, and the like. Examples of the ring formed by bonding R ³ and R ⁴ to each other include a pyrrolidone ring which may have a substituent.

The (meth) acrylic resin A has only one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2), or a combination of two or more kinds. May include. For example, the (meth) acrylic resin A may contain only one group represented by the general formula (1) or a combination of two or more. For example, the (meth) acrylic resin A may contain only one group represented by the general formula (2) or a combination of two or more. For example, the (meth) acrylic resin A may contain one or more groups represented by the general formula (1) and / or one or more groups represented by the general formula (2).

The (meth) acrylic resin A preferably has two or more groups selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2).

The group represented by the general formula (1) and / or the group represented by the general formula (2) is directly or via a divalent linking group to the carbon atom of the main chain of the (meth) acrylic resin A. It is preferably bonded, and more preferably directly bonded to the carbon atom of the main chain of the (meth) acrylic resin A. Examples of the divalent linking group include an alkylene group, an alkynylene group, an alkenylene group, an arylene group, a heteroarylene group, −O−, a carbonyl group (-(C = O) −), and a carbonyloxy group (− (C =). Examples thereof include a divalent group such as O) -O-) and a group in which two or more such divalent groups are combined.

The (meth) acrylic resin A preferably has a β-dicarbonyl group and / or an alkyl group, and has a β-dicarbonyl group, for example, from the viewpoint of improving image density, improving color development, and reducing image strike-through. And having an alkyl group is more preferred. At least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the following general formula (2), the β-dicarbonyl group, and the alkyl group are, for example, two of them. One or three may be included in the same unit, but at least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the following general formula (2), β- It is preferable that the dicarbonyl group and the alkyl group are contained in different units.

Examples of the β-dicarbonyl group include a β-diketone group such as an acetoacetyl group and a propionacetyl group, and a β-ketoate group such as an acetoxy group and a propion acetoxy group. The (meth) acrylic resin A may contain only one or a plurality of these β-dicarbonyl groups.

As the alkyl group, an alkyl group having 8 to 22 carbon atoms is preferable, and an alkyl group having 12 to 22 carbon atoms is more preferable. The alkyl group having 8 to 22 carbon atoms may be a straight chain or a branched chain. Specific examples thereof include an octyl group, a nonyl group, a decyl group, an undecylic group, a dodecyl group, a tridecylic group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecylic group, an eicosyl group and a docosyl group. .. The (meth) acrylic resin A may contain only one type or a plurality of types of these alkyl groups.

The (meth) acrylic resin A may contain an acidic group such as a sulfo group or a carboxy group.

The (meth) acrylic resin A is a unit having at least one group selected from the group consisting of a group represented by the general formula (1) and a group represented by the general formula (2) (hereinafter, "unit Ya". ”) Is included.
The (meth) acrylic resin A is, for example, a unit having at least one group selected from the group consisting of a group represented by the general formula (1) and a group represented by the general formula (2) (“Unit Ya”. ”) And a unit having a β-dicarbonyl group (hereinafter, may be referred to as“ unit Yb ”) and / or a unit having an alkyl group (hereinafter, may be referred to as“ unit Yc ”). It is preferable to include the unit Ya, the unit Yb, and the unit Yc.

The unit (unit Ya) having at least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2) is, for example, a (meth) acrylic resin. At least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2) is bonded to the carbon atom of the main chain of A directly or via a linking group. The unit you are doing is listed. Examples of such a unit include a unit represented by the following general formula (3), a unit represented by the following general formula (4), and the like.

In the general formula (3), ^{R 1} and ^{R 2} are each the same as ^{R 1} and ^{R 2} in the general formula (1), the same applies to its preferred range. R ⁵ represents a hydrogen atom or a methyl group. L ¹ represents a divalent linking group or a single bond.
In the general formula (4), ^{R 3} and ^{R 4} are each the same as ^{R 3} and ^{R 4} in the general formula (2), thereof it is also the same preferable ranges. R ⁶ represents a hydrogen atom or a methyl group. L ² represents a divalent linking group or a single bond.
Examples of the divalent linking group include an alkylene group, an alkynylene group, an alkenylene group, an arylene group, a heteroarylene group, −O−, a carbonyl group (-(C = O) −), and a carbonyloxy group (− (C =). Examples thereof include a divalent group such as O) -O-) and a group in which two or more such divalent groups are combined.

As the unit Ya, for example, a monomer having at least one group selected from the group consisting of a group represented by the general formula (1) and a group represented by the general formula (2) described later (hereinafter, “monomer Ya”). A unit derived from) can be used.

The (meth) acrylic resin A may contain only one type of unit Ya or two or more types. The (meth) acrylic resin A has, for example, one or more units represented by the general formula (3) and / or one or more units represented by the general formula (4). May include.

The unit having a β-dicarbonyl group (unit Yb) may be, for example, an acrylic unit or a methacrylic unit.
Examples of the unit Yb include a unit in which a carbonyl group is bonded to a carbon atom of the main chain and a β-dicarbonyl group is bonded to the carbon atom of the carbonyl group directly or via a linking group.
As the unit Yb, a unit derived from (meth) acrylate having a β-dicarbonyl group, a unit derived from (meth) acrylamide having a β-dicarbonyl group, and the like are preferable. The (meth) acrylate having a β-dicarbonyl group includes, for example, a β-diketone group or a β-keto acid ester group indirectly bonded to the carbon atom of the carbonyl (CO) of the acryloyl group or the methacryloyl group (meth). ) Acrylate is a preferred example. The (meth) acrylamide having a β-dicarbonyl group includes, for example, a β-diketone group or a β-keto acid ester group indirectly bonded to the carbon atom of the carbonyl (CO) of the acryloyl group or the methacryloyl group (meth). ) Acrylamide is a preferred example. As the unit Yb, for example, a unit derived from a monomer having a β-dicarbonyl group described later (hereinafter, may be referred to as “monomer Yb”) can be used.
The (meth) acrylic resin A may contain only one type of unit Yb or two or more types.

The unit having an alkyl group (unit Yc) may be, for example, an acrylic unit having an alkyl group or a methacrylic unit.
Examples of unit Yc, for example, in the main chain carbon atoms of the (meth) acrylic resin A, a unit group represented by -COOR ^e are bonded, R ^e is an alkyl group (preferably a carbon A unit of number 8 to 22, more preferably an alkyl group having 12 to 22 carbon atoms). As the unit Yc, for example, a unit derived from a monomer having an alkyl group described later (hereinafter, may be referred to as “monomer Yc”) can be used.
The (meth) acrylic resin A may contain only one type or two or more types of the unit Yc.

The (meth) acrylic resin A may contain other units.

The unit (unit Ya) having at least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2) is 5 to 30 with respect to the entire polymer. It is preferably by mass%, more preferably 10 to 25% by mass or more.
The unit having a β-dicarbonyl group (unit Yb) is preferably 5 to 30% by mass, more preferably 10 to 20% by mass, based on the total amount of the polymer.
The unit having an alkyl group (unit Yc) is preferably 40 to 90% by mass, more preferably 50 to 90% by mass, still more preferably 60 to 80% by mass or more based on the entire polymer.
Here, the entire polymer is based on all the units constituting the (meth) acrylic resin A.

The (meth) acrylic resin A is, for example, a monomer (monomer Ya) having at least one group selected from the group consisting of a group represented by the general formula (1) and a group represented by the general formula (2). It may be a homopolymer obtained by polymerizing the above, a copolymer obtained by polymerizing a monomer mixture containing the monomer Ya, or such a homopolymer or a derivative of the copolymer. The monomer mixture preferably contains a monomer Ya, a monomer having a β-dicarbonyl group (monomer Yb) and / or a monomer having an alkyl group (monomer Yc), and the monomer Ya, the monomer Yb, and the monomer Yc. It is more preferable to include.

As an example of a monomer (monomer Ya) having at least one group selected from the group consisting of the group represented by the general formula (1) and the group represented by the general formula (2), for example, the following general formula (5) ), The monomer represented by the following general formula (6), and the like.

In general formula (5), ^{R 1} and ^{R 2} are each the same as ^{R 1} and ^{R 2} in the general formula (1), the same applies to its preferred range. R ⁵ represents a hydrogen atom or a methyl group. L ¹ represents a divalent linking group or a single bond.
In general formula (6), ^{R 3} and ^{R 4} are each the same as ^{R 3} and ^{R 4} in the general formula (2), thereof it is also the same preferable ranges. R ⁶ represents a hydrogen atom or a methyl group. L ² represents a divalent linking group or a single bond.
Examples of the divalent linking group include an alkylene group, an alkynylene group, an alkenylene group, an arylene group, a heteroarylene group, −O−, a carbonyl group (-(C = O) −), and a carbonyloxy group (− (C =). Examples thereof include a divalent group such as O) -O-) and a group in which two or more such divalent groups are combined.

Specific examples of the monomer represented by the general formula (5) or (6) include dimethylacrylamide, acryloylmorpholine, N-vinyl-2-pyrrolidone and the like.

The monomer having a β-dicarbonyl group (monomer Yb) is preferably, for example, a monomer having an acryloyl group or a methacryloyl group and a β-dicarbonyl group. Preferred examples of the monomer Yb include (meth) acrylate having a β-dicarbonyl group and (meth) acrylamide having a β-dicarbonyl group. Specific examples of the monomer Yb include acetoacetoxyalkyl (meth) acrylate such as acetoacetoxyethyl (meth) acrylate, hexadione (meth) acrylate, and acetoacetoxyalkyl (meth) acrylamide such as acetoacetoxyethyl (meth) acrylamide. Can be mentioned.

As the monomer having an alkyl group (monomer Yc), for example, a monomer having an acryloyl group or a methacryloyl group and an alkyl group is preferable. Examples of the monomer Yc include alkyl (meth) acrylates, preferably alkyl (meth) acrylates having an alkyl group having 8 to 22 carbon atoms, and alkyl (meth) having an alkyl group having 12 to 22 carbon atoms. Acrylate is more preferred. Specific examples of the monomer Yc include behenyl (meth) acrylate and lauryl (meth) acrylate (dodecyl (meth) acrylate).

The monomer mixture may contain other monomers.
The blending amount of each monomer in the monomer mixture can be adjusted, for example, to be a preferable ratio of each of the above units.

These monomers can be polymerized, for example, by known radical polymerization. The reaction system is preferably solution polymerization or dispersion polymerization. In the polymerization reaction, for example, a polymerization initiator, a chain transfer agent, a polymerization inhibitor, a polymerization accelerator, a dispersant and the like can be appropriately added to the reaction system. As the polymerization initiator, for example, t-butylperoxy-2-ethylhexanoate or the like can be used. The polymerization solvent (reaction solvent) used for solution polymerization is not particularly limited, but one capable of dispersing or dissolving the resin obtained by polymerization is preferable.

As the dispersant, the (meth) acrylic resin A can be used alone or in combination of two or more.

The total amount of the acidic resin and the low molecular weight amine compound with respect to the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A is preferably 10% by mass or more, more preferably 20% by mass or more, and more preferably 30% by mass or more. Is even more preferable. On the other hand, the total amount of the acidic resin and the low molecular weight amine compound with respect to the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A is preferably 90% by mass or less, more preferably 80% by mass or less, and 70% by mass. % Or less is more preferable. The total amount of the acidic resin and the low molecular weight amine compound with respect to the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A is, for example, preferably 10 to 90% by mass, more preferably 20 to 80% by mass. More preferably, it is 30 to 70% by mass.

The amount of the (meth) acrylic resin A with respect to the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A is preferably 10% by mass or more, more preferably 20% by mass or more, and more preferably 30% by mass or more. More preferred. On the other hand, the amount of the (meth) acrylic resin A with respect to the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A is preferably 90% by mass or less, more preferably 80% by mass or less, and 70% by mass. The following is more preferable. The amount of the (meth) acrylic resin A with respect to the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A is, for example, preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and 30. ~ 70% by mass is more preferable.

The low molecular weight amine compound is preferably in an amount such that the molar ratio (basic group / acidic group) of the basic group of the low molecular weight amine compound to the acidic group of the acidic resin is 0.5 to 1.5, and is 0. More preferably, the amount is .8 to 1.2. Here, when a surface-treated acidic water-dispersible resin such as attaching an acidic resin particle dispersant to the surface of the resin particles is used, the acidic group of the acidic resin is the acidic group of the acidic resin particle dispersant. Also includes.

The mass ratio of the acidic resin to the (meth) acrylic resin A (acidic resin: (meth) acrylic resin A) is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and 30: 70 to 70:30 is more preferable.

The acidic resin is preferably 0.1 to 20% by mass, more preferably 0.1 to 10% by mass, still more preferably 0.5 to 10% by mass, based on the total amount of the ink.

The (meth) acrylic resin A is preferably 0.1 to 10% by mass, more preferably 0.5 to 10% by mass, preferably 1 to 5% by mass, and 1.5 to 5% by mass with respect to the total amount of ink. % Is more preferable.

The content of the dispersant is 0.1% by mass or more based on the total amount of the ink as the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A from the viewpoint of ensuring the dispersibility of the pigment. It is preferably 1% by mass or more, more preferably 2% by mass or more. On the other hand, the content of the dispersant is the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A from the viewpoint of the viscosity of the ink and the storage stability in a high temperature environment, with respect to the total amount of the ink. , 20% by mass or less, more preferably 10% by mass or less, still more preferably 8% by mass or less. The content of the dispersant is preferably 0.1 to 20% by mass, for example, 1 to 10% by mass, based on the total amount of the ink, as the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A. Is more preferable, and 2 to 8% by mass is further preferable.

The amount of the dispersant may be such that the total amount of the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A is 0.1 to 5 with respect to the pigment 1 in terms of mass ratio. The amount is preferably 0.1 to 1, more preferably 0.1 to 1.

As the non-aqueous solvent, either a non-polar organic solvent or a polar organic solvent can be used for the ink. These may be used alone or in combination of two or more as long as they form a single phase. In the present embodiment, it is preferable to use a water-insoluble organic solvent that does not uniformly mix with the same volume of water at 1 atm and 20 ° C. as the non-aqueous solvent.

As the non-polar organic solvent, a petroleum-based hydrocarbon solvent such as an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, and an aromatic hydrocarbon solvent can be preferably mentioned.
Examples of the aliphatic hydrocarbon solvent and the alicyclic hydrocarbon solvent include non-aqueous solvents such as paraffin-based, isoparaffin-based, and naphthenic-based solvents. Commercially available products include No. 0 Solvent L, No. 0 Solvent M, No. 0 Solvent H, Cactus Normal Paraffin N-10, Cactus Normal Paraffin N-11, Cactus Normal Paraffin N-12, Cactus Normal Paraffin N-13, Cactus Normal. Paraffin N-14, Cactus Normal Paraffin N-15H, Cactus Normal Paraffin YHNP, Cactus Normal Paraffin SHNP, Isosol 300, Isosol 400, Teclean N-16, Teclean N-20, Teclean N-22, AF Solvent No. 4, AF Solvent No. 5, AF Solvent No. 6, AF Solvent No. 7, Naftesol 160, Naftesol 200, Naftesol 220 (all manufactured by JXTG Energy Co., Ltd.); Isopar G, Isopar H, Isopar L, Isopar M, Exol D40, Exol D60, Exol D80, Exol D95, Exol D110, Exol D130 (all manufactured by Exxon Mobile); Moresco White P-40, Moresco White P-60, Moresco White P-70, Moresco White P-80, Moresco White P-100, Moresco White P-120, Moresco White P-150, Moresco White P-200, Moresco White P-260, Moresco White P-350P (all manufactured by MORESCO Co., Ltd.) and the like are preferably mentioned. be able to.
Preferred examples of the aromatic hydrocarbon solvent include Grade Alken L, Grade Alken 200P (all manufactured by JXTG Energy Co., Ltd.), Solbesso 100, Solbesso 150, Solbesso 200, and Solbesso 200ND (all manufactured by ExxonMobil). it can.
The distillation initial distillation point of the petroleum-based hydrocarbon solvent is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and even more preferably 200 ° C. or higher. The distillation initial distillation point can be measured according to JIS K0066 "Distillation test method for chemical products".

As the polar organic solvent, a fatty acid ester solvent, a higher alcohol solvent, a higher fatty acid solvent and the like can be preferably mentioned.
For example, isononyl isononanoate, isodecyl isononanoate, isotridecyl isononanoate, methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, hexyl palmitate, isooctyl palmitate, isostearyl palmitate, methyl oleate. , Ethyl oleate, isopropyl oleate, butyl oleate, hexyl oleate, methyl linoleate, ethyl linoleate, isobutyl linoleate, butyl stearate, hexyl stearate, isooctyl stearate, isopropyl isostearate, 2-octyl pivalate Fatty acid ester-based solvent having 13 or more carbon atoms, preferably 16 to 30 carbon atoms in one molecule such as decyl, methyl soybean oil, isobutyl soybean oil, methyl tall oil, isobutyl tall oil, etc .; isomyristyl alcohol, isopalmityl alcohol, stearyl, etc. Higher alcoholic solvents with 6 or more, preferably 12 to 20 carbon atoms in one molecule, such as alcohols, isostearic alcohols, oleyl alcohols, isoeicosyl alcohols, decyltetradecanols; lauric acid, isomiristic acid, palmitic acid. , Isopalmitic acid, α-linolenic acid, linoleic acid, oleic acid, isostearic acid and the like, which have 12 or more carbon atoms in one molecule, preferably 14 to 20 higher fatty acid-based solvents and the like.
The boiling point of a polar organic solvent such as a fatty acid ester solvent, a higher alcohol solvent, or a higher fatty acid solvent is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 250 ° C. or higher. preferable. The non-aqueous solvent having a boiling point of 250 ° C. or higher also includes a non-aqueous solvent having a boiling point.

The amount of the non-aqueous solvent can be adjusted as appropriate. The non-aqueous solvent is preferably 60% by mass or more, more preferably 70% by mass or more, based on the total amount of ink. On the other hand, the amount of the non-aqueous solvent is preferably 99% by mass or less, more preferably 95% by mass or less, based on the total amount of the ink. The amount of the non-aqueous solvent is preferably, for example, 60 to 99% by mass, more preferably 70 to 95% by mass, based on the total amount of the ink.

In addition to the above components, the oil-based ink may contain various additives. As the additive, a nozzle clogging inhibitor, an antioxidant, a conductivity adjuster, a viscosity adjuster, a surface tension adjuster, an oxygen absorber, a dye and the like can be appropriately added. These types are not particularly limited, and those used in the art can be used.

The amount of water in the ink is preferably 1% by mass or less, more preferably less than 1% by mass, further preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, based on the total amount of ink.
The total amount of the dispersant and the pigment in the ink is preferably 1 to 40% by mass, preferably 1 to 40% by mass, as the total amount of the pigment, the acidic resin, the low molecular weight amine compound and the (meth) acrylic resin A with respect to the total amount of the ink. 30% by mass is more preferable.

The method for producing the oil-based inkjet ink described above is not particularly limited. For the production of the above-mentioned oil-based inkjet ink, for example, the in-liquid drying method can be preferably used, and the in-oil drying method of a water-in-oil (W / O) type emulsion can be particularly preferably used.

An example of a method for producing an oil-based inkjet ink using a method for drying a water-in-oil emulsion in oil includes, for example, producing a dispersant by a method using a method for drying a water-in-oil emulsion in oil. Can be mentioned. As such a method, for example, a water-in-oil emulsion containing a continuous phase containing a non-aqueous solvent and a (meth) acrylic resin A and a dispersed phase containing water, an acidic water-dispersible resin and a low-molecular-weight amine compound. (Hereinafter, sometimes referred to as “step 1”) and the dispersion formed by removing water from the water-in-oil emulsion and forming an acidic resin, a low molecular weight amine compound, and a (meth) acrylic resin A. A step of obtaining a dispersant dispersion containing an agent (hereinafter, may be referred to as "step 2") and a step of mixing the dispersant dispersion and the pigment and dispersing the pigment (hereinafter, referred to as "step 3"). There is also a method including). In this method, in step 2, the dispersant dispersion can be obtained as a resin particle dispersion in which the dispersant is dispersed as resin particles. However, the method for producing ink is not limited to this method. The form of the dispersant is also not limited to the resin particles.
This method, which uses a water-in-oil emulsion drying method in oil, does not require the use of a volatile organic solvent and is excellent in safety.

Since the (meth) acrylic resin A has a group represented by the general formula (1) or (2), it is easy to be oriented at the interface between the aqueous phase and the oil phase, and an emulsion is easily formed. Therefore, from this viewpoint as well. , A method for producing such a water-in-oil (W / O) type emulsion using an in-oil drying method is preferable.

As the non-aqueous solvent, the (meth) acrylic resin A, the acidic water-dispersible resin, the low molecular weight amine compound, and the pigment, those described in the description of the ink components can be used. For example, as the acidic water-dispersible resin, among the water-dispersible resins of the acidic resin described in the description of the ink components, an acidic water-dispersible (meth) acrylic resin, an acidic water-dispersible urethane resin, and the like are preferable. , Acrylic urethane urea-based water-dispersible resin is more preferable.
As the water, tap water, ion-exchanged water, deionized water and the like can be used.

In the water-in-oil emulsion produced in step 1, the continuous phase and the dispersed phase may contain other components.

The amount (solid content) of the acidic water-dispersible resin is preferably 1 to 60% by mass, more preferably 10 to 50% by mass, still more preferably 20 to 40% by mass, based on the total amount of the dispersed phase. The amount (solid content) of the acidic water-dispersible resin is preferably 0.1 to 30% by mass, more preferably 1 to 20% by mass, still more preferably 5 to 15% by mass, based on the total amount of the water-in-oil emulsion. ..

The amount (solid content) of the acidic water-dispersible resin is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 14% by mass or more, based on the total amount of the dispersant dispersion obtained in step 2. The amount (solid content) of the acidic water-dispersible resin is preferably 40% by mass or less, more preferably 30% by mass or less, based on the total amount of the dispersant dispersion obtained in step 2. The amount (solid content) of the acidic water-dispersible resin is preferably 5 to 40% by mass, more preferably 10 to 40% by mass, and 14 to 30% by mass with respect to the total amount of the dispersant dispersion obtained in step 2. More preferred.

In the water-in-oil emulsion, the amount of the low molecular weight amine compound is preferably used in such an amount that the amount of the basic group thereof is in the above-mentioned preferable molar range with respect to the acidic group of the acidic water-dispersible resin.
In the water-in-oil emulsion, the amount of water is preferably 40 to 99% by mass, more preferably 50 to 90% by mass, still more preferably 60 to 80% by mass, based on the total amount of the dispersed phases. The amount of water is preferably 1 to 50% by mass, more preferably 5 to 50% by mass, still more preferably 10 to 40% by mass, based on the total amount of the water-in-oil emulsion.

In the water-in-oil emulsion, the amount of water is such that the amount of acidic water-dispersible resin (solid content) in the dispersed phase is relative to the amount of water from the viewpoint of maintaining the stability of the water-in-oil emulsion in step 1. The amount is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 35% by mass or more, and 40% by mass or more. Is more preferable. On the other hand, the amount of water is preferably such that the amount (solid content) of the acidic aqueous dispersible resin in the dispersed phase is 80% by mass or less, and is 75% by mass or less, based on the amount of water. Is more preferable. In the water-in-oil emulsion, the amount of water is preferably such that, for example, the amount (solid content) of the acidic water-dispersible resin in the dispersed phase is 20 to 80% by mass with respect to the amount of water. , 30 to 80% by mass, more preferably 35 to 80% by mass, and even more preferably 40 to 75% by mass.

The (meth) acrylic resin A may be used by including the entire amount used for the ink in the water-in-oil emulsion obtained in step 1, but only a part of the (meth) acrylic resin A can be used in the water-in-oil emulsion obtained in step 1. The rest may be mixed together with the pigment, the dispersant dispersion, and the like when the pigment and the dispersant dispersion are mixed in, for example, in step 3. The (meth) acrylic resin A added in step 3 or the like may be the same as or different from the (meth) acrylic resin A contained in the water-in-oil emulsion of step 1.

In the water-in-oil emulsion, the amount of the (meth) acrylic resin A is preferably 1 to 60% by mass, more preferably 5 to 50% by mass, still more preferably 10 to 40% by mass, based on the total amount of the continuous phase. ..
In the water-in-oil emulsion, the amount of the (meth) acrylic resin A is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, and 10 to 20% by mass with respect to the total amount of the water-in-oil emulsion. More preferred.

The entire amount of the non-aqueous solvent used for the ink may be contained in the water-in-oil emulsion obtained in step 1, but only a part of the non-aqueous solvent may be contained in the water-in-oil emulsion obtained in step 1. The rest may be mixed together with the pigment, the dispersant dispersion, and the like when the pigment and the dispersant dispersion are mixed in, for example, in step 3. The non-aqueous solvent added in step 3 and the like may be the same as or different from the non-aqueous solvent contained in the water-in-oil emulsion of step 1.

In the water-in-oil emulsion, the amount of the non-aqueous solvent is preferably 40 to 99% by mass, more preferably 50 to 95% by mass, still more preferably 60 to 90% by mass, based on the total amount of the continuous phase.
In the water-in-oil emulsion, the amount of the non-aqueous solvent is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, based on the total amount of the water-in-oil emulsion.

In step 1, the method for obtaining a water-in-oil emulsion is not particularly limited.
The water-in-oil emulsion can be produced, for example, by mixing and emulsifying a dispersed phase component and a continuous phase component.
From the viewpoint of improving the dispersion stability of the ink and the resulting improvement in scratch resistance, it is preferable to separately prepare the mixture for continuous phase containing the components of the continuous phase and the mixture for the dispersed phase containing the components of the dispersed phase in advance. .. Next, it is preferable to add the dispersion phase mixture to the continuous phase mixture and emulsify it. The emulsification treatment may be carried out using, for example, an emulsifier such as an ultrasonic homogenizer. The emulsification treatment may be carried out, for example, while adding the dispersion phase mixture to the continuous phase mixture, or may be carried out after adding the dispersion phase mixture to the continuous phase mixture, for example.

From the viewpoint of reducing the emulsion particle size, thereby improving the dispersion stability of the obtained ink and thereby improving the scratch resistance, for example, step 1 is carried out in step 1 with an acidic water-dispersible resin, a low molecular weight amine compound and the like. A step of obtaining a dispersion phase mixture containing water (hereinafter, may be referred to as "step a-1") and a step of obtaining a continuous phase mixture containing (meth) acrylic resin A and a non-aqueous solvent (hereinafter, "step a-1"). It may include a step (sometimes referred to as “step a-2”) and a step of adding the dispersion phase mixture to the continuous phase mixture and emulsifying the mixture (hereinafter, also referred to as “step a-3”). preferable. In step a-1, for example, an acidic water-dispersible resin, a low-molecular-weight amine compound, water, and if necessary, other components can be mixed to obtain a dispersion phase mixture. In step a-2, for example, the (meth) acrylic resin A, the non-aqueous solvent, and other components, if necessary, can be mixed to obtain a continuous phase mixture. In step a-3, the dispersion phase mixture obtained in step a-1 is added to the continuous phase mixture obtained in step a-2 to emulsify. In step a-3, the emulsification treatment may be carried out, for example, while adding the dispersion phase mixture to the continuous phase mixture, or may be carried out after adding the dispersion phase mixture to the continuous phase mixture, for example. The emulsification treatment may be carried out using, for example, an emulsifier such as an ultrasonic homogenizer.

In the water-in-oil emulsion, from the viewpoint of improving production efficiency, the mixture for the continuous phase and the mixture for the dispersed phase are not prepared separately in advance, but for example, the components of the continuous phase and the components of the dispersed phase are prepared at once. It is preferable to mix and emulsify the obtained mixture with an emulsifier or the like.
From the viewpoint of improving production efficiency, step 1 is, for example, a step of mixing an acidic water-dispersible resin, a low molecular weight amine compound, water, a (meth) acrylic resin A, and a non-aqueous solvent to obtain a mixture (hereinafter referred to as a step). It is preferable that the step includes a step (sometimes referred to as step “b-1”) and a step of emulsifying the obtained mixture (hereinafter, also referred to as step “b-2”). When the dispersed phase and / or the continuous phase contains other components, in step b-1, the other components are added together with the acidic water-dispersible resin, the low molecular weight amine compound, water, the (meth) acrylic resin A, and the non-aqueous solvent. May be mixed. In step b-2, the emulsification treatment may be carried out using, for example, an emulsifier such as an ultrasonic homogenizer.

In step 1, the water-in-oil emulsion has a mass ratio of 20 to 50% by mass of the dispersed phase and 80 to 50% by mass of the continuous phase with respect to the total amount of the water-in-oil emulsion as the mass ratio in the state before removing water. Is preferable.

In step 2, the water in the dispersed phase of the water-in-oil emulsion is removed. As a result, resin particles are formed by the remaining dispersed phase component and the continuous phase component (meth) acrylic resin A, and the dispersant formed by the acidic resin, the low molecular weight amine compound, and the (meth) acrylic resin A. Can be obtained as a dispersant dispersion containing the resin particles. In this way, in step 2, a dispersant dispersion containing the dispersant and the non-aqueous solvent can be obtained. Further, the (meth) acrylic resin A may be further added to the dispersant obtained in step 2.

As a method for removing water, for example, decompression, heating, bubbling, addition of a hygroscopic agent, or a combination thereof can be used. As the conditions for depressurization and / or heating, conditions can be adopted in which water is removed but the continuous phase non-aqueous solvent remains. For depressurization, for example, an evaporator can be used. The heating temperature is preferably 30 ° C. or higher, more preferably 40 to 100 ° C., and even more preferably 60 ° C. to 90 ° C. For example, heating at normal pressure is also preferable. As the bubbling, it is preferable to promote evaporation by blowing a gas into the liquid and bubbling. Examples of the hygroscopic agent include zeolite and the like.

In step 2, the dispersed phase water is preferably removed in an amount of 80% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more based on the amount before removal. It is more preferable that 99% by mass or more is removed.

In the dispersant dispersion obtained in step 2, the solid content of the dispersed phase component of the aqueous emulsion in oil is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, based on the total amount of the dispersant dispersion.
In the dispersant dispersion obtained in step 2, the amount of the dispersant is 20 to 60% by mass as the total amount of the solid content of the dispersed phase component and the solid content of the continuous phase component of the aqueous emulsion in oil. Preferably, 30 to 50% by mass is more preferable.

In step 3, the dispersant dispersion and the pigment are mixed to disperse the pigment.
In step 3, the dispersant dispersion and the pigment are mixed. If necessary, the (meth) acrylic resin A and / or the non-aqueous solvent and the like are mixed together with the dispersant dispersion and the pigment. You may. The (meth) acrylic resin A added in step 3 or the like may be the same as or different from the (meth) acrylic resin A contained in the water-in-oil emulsion of step 1. The non-aqueous solvent added in step 3 and the like may be the same as or different from the non-aqueous solvent contained in the water-in-oil emulsion of step 1.
The amount of each material used in step 3 is not particularly limited, but can be appropriately determined in consideration of the amount of each component in the ink.

In step 3, the pigment may be dispersed, for example, by mixing the dispersant dispersion, the pigment, and, if necessary, the (meth) acrylic resin A and / or the non-aqueous solvent. This may be performed after mixing the agent dispersion, the pigment, and if necessary, the (meth) acrylic resin A and / or the non-aqueous solvent or the like. A bead mill or the like can be used for dispersion.

This method for producing an oil-based inkjet may further include other steps.
By mixing the dispersant dispersion, the pigment, and if necessary (meth) acrylic resin A and / or a non-aqueous solvent, etc., the pigment is dispersed, and if necessary, another step is performed to make it oily. Inkjet ink can be obtained. In the oil-based inkjet ink, the pigment and the dispersant may form colored resin particles, and examples of such colored resin particles include those in which the pigment is coated with the dispersant.

The average particle size of the colored resin particles in the ink is preferably 50 to 300 nm, more preferably 80 to 200 nm. The average particle size of the colored resin particles in the ink is a volume-based average particle size by a dynamic scattering method. For example, a dynamic light scattering type particle size distribution measuring device "nanoparticle analyzer nanoPartica" manufactured by Horiba Seisakusho Co., Ltd. It can be measured using "SZ-100" or the like.

The printing method using the oil-based inkjet ink is not particularly limited, and any method such as a piezo method, an electrostatic method, or a thermal method may be used. When an inkjet recording device is used, it is preferable to eject the ink according to the present embodiment from the inkjet head based on a digital signal so that the ejected ink droplets adhere to the recording medium.

The appropriate range of the viscosity of the oil-based inkjet ink varies depending on the nozzle diameter of the ejection head of the inkjet recording system, the ejection environment, etc., but in general, it is preferably 5 to 30 mPa · s at 23 ° C., and 5 to 15 mPa · s. It is more preferable that there is, and it is more preferable that it is about 10 mPa · s.

In the present embodiment, the recording medium is not particularly limited, and a printing paper such as plain paper, coated paper, or special paper, a cloth, an inorganic sheet, a film, an OHP sheet, or the like is used as a base material and an adhesive layer is formed on the back surface. An adhesive sheet or the like provided with the above can be used. Among these, printing paper such as plain paper and coated paper can be preferably used from the viewpoint of ink permeability.

Here, the plain paper is a paper in which an ink receiving layer, a film layer, or the like is not formed on the ordinary paper. Examples of plain paper include high-quality paper, medium-quality paper, PPC paper, stencil paper, recycled paper, and the like. Plain paper is a paper in which ink easily permeates because paper fibers having a thickness of several μm to several tens of μm form voids of several tens to several hundreds of μm.

Further, as the coated paper, an inkjet coated paper such as matte paper, glossy paper, or semi-glossy paper, or so-called coated printing paper can be preferably used. Here, the coating printing paper is a printing paper that has been conventionally used for letterpress printing, offset printing, gravure printing, etc., and has an inorganic pigment such as clay or calcium carbonate on the surface of high-quality paper or medium-quality paper. , A printing paper provided with a coating layer using a paint containing a binder such as starch. Coated printing paper can be used for finely coated paper, high-quality lightweight coated paper, medium-quality lightweight coated paper, high-quality coated paper, medium-quality coated paper, art paper, cast-coated paper, etc., depending on the amount of paint applied and the coating method. being classified.

In the method for producing a dispersant according to one embodiment of the present invention, a continuous phase containing a non-aqueous solvent and a (meth) acrylic resin A and a dispersed phase containing water, an acidic aqueous dispersible resin and a low molecular weight amine compound are used. A step of obtaining a water-in-oil emulsion containing the mixture (hereinafter, may be referred to as "step A") and a step of removing water from the water-in-oil emulsion (hereinafter, may be referred to as "step B"). It is a method for producing a dispersant including.
By this method for producing a dispersant, a dispersant that can be used for the above-mentioned oil-based inkjet ink can be obtained. However, the method for producing the above-mentioned oil-based inkjet ink dispersant is not limited to this method.

Step A is the same as step 1 described in the above-mentioned example of the method for producing an oil-based inkjet ink. In step B, the method for removing water and the amount of water removed are the same as the method for removing water and the amount of water removed in step 2 described in the above-mentioned example of the method for producing an oil-based inkjet ink. is there.

In step B, the water in the dispersed phase of the water-in-oil emulsion is removed, whereby resin particles are formed by the remaining dispersed phase component and the continuous phase component (meth) acrylic resin A, and the acidic resin is low. A dispersant dispersion containing the molecular amine compound and the dispersant formed of the (meth) acrylic resin A as the resin particles can be obtained.

The method for producing the dispersant may further include other steps such as a step of adding the (meth) acrylic resin A.

Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the following examples.
Through the following examples and comparative examples, the common components are the same unless otherwise specified. Unless otherwise specified, "%" indicates "mass%".
The blending amount of each material shown in Tables 1 to 3 is expressed in parts by mass. The blending amount of each material shown in Tables 4 and 5 is expressed in% by mass. The blending amount of each material in Tables 1 to 5 is the amount including the volatile content for the material containing the volatile content.

<Ink material>
The raw materials for the inks of Examples and Comparative Examples are shown below.

Copper Phthalocyanine Blue: Heliogen Blue D7115F (manufactured by BASF)
Azo Rake Red: Permanent Ruby P-L5b01 (manufactured by Clariant Japan Co., Ltd.)
Carbon Black: MOGUL L (manufactured by Cabot Specialty Chemicals)

Urethane urea resin aqueous dispersion 1: Manufactured by the method described below (aqueous dispersion containing acidic urethane urea resin and triethanolamine, active ingredient 30%)
Urethane urea resin aqueous dispersion 2: Manufactured by the method described below (aqueous dispersion containing acidic urethane urea resin and dimethylethanolamine, active ingredient 30%)
Urethane urea resin aqueous dispersion 3: Manufactured by the method described below (aqueous dispersion containing acidic urethane urea resin and triethylamine, active ingredient 30%)

(Meta) Acrylic Resin Aqueous Dispersion 1: Manufactured by the method described below (Aqueous dispersion containing acidic (meth) acrylic resin and dimethylethanolamine, active ingredient 30%)

Urethane-based resin aqueous dispersion 1: Manufactured by the method described below (aqueous dispersion containing acidic urethane-based resin and dimethylethanolamine, active ingredient 30%)

Urethane resin solution 1: Manufactured by the method described below (acidic urethane resin solution, 50% active ingredient)
Basic urethane urea resin aqueous dispersion 1: Superflex 620 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., basic urethane urea aqueous dispersion, active ingredient 30%)

(Meta) acrylic resin solution a: Manufactured by the method described below ((meth) acrylic resin solution, active ingredient 40%, solvent is fatty acid ester solvent)
(Meta) acrylic resin solution b: Manufactured by the method described below ((meth) acrylic resin solution, active ingredient 40%, solvent is fatty acid ester solvent)
(Meta) acrylic resin solution c: Manufactured by the method described below ((meth) acrylic resin solution, active ingredient 40%, solvent is fatty acid ester solvent)
(Meta) acrylic resin solution d: Manufactured by the method described below ((meth) acrylic resin solution, active ingredient 40%, solvent is fatty acid ester solvent)
(Meta) acrylic resin solution e: Manufactured by the method described below ((meth) acrylic resin solution, active ingredient 40%, solvent is petroleum hydrocarbon solvent)

Acid Polymer 1: Solsparse 21000 (manufactured by Japan Lubrizol Co., Ltd.) (100% active ingredient)

Fatty acid ester solvent 1: Isopropyl myristate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Petroleum Hydrocarbon Solvent 1: Exor D130 (manufactured by ExxonMobil)
Higher alcohol solvent 1: Oleyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

<Manufacture of Urethane Urea Resin Water Dispersions 1-3>
In a four-necked flask, 767.6 parts by mass of polytetramethylene glycol (manufactured by Mitsubishi Chemical Co., Ltd.), 55.5 parts by mass of 2,2-dimethylolbutanoic acid (manufactured by HighChem Co., Ltd.), 1,4-butanediol 23.7 parts by mass (manufactured by Mitsubishi Chemical Co., Ltd.) and 203.2 parts by mass of hexamethylene diisocyanate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) at 80 ° C. in 724.4 parts by mass of methyl ethyl ketone (manufactured by Tokyo Kasei Kogyo Co., Ltd.) The reaction was carried out for 6 hours. Then, 21.8 parts by mass of hexanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was added thereto. 2000 parts by mass of ion-exchanged water at 50 ° C. was added to this solution, and the pH was adjusted to 8 with triethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.). Then, methyl ethyl ketone was removed at 50 ° C. and under reduced pressure. Ion-exchanged water was added thereto to adjust the solid content to 30% by mass to obtain an acidic urethane urea resin and an aqueous dispersion (active ingredient 30%) containing triethanolamine as a low molecular weight amine compound. This is referred to as urethane urea-based resin water dispersion 1.

Except for using dimethylethanolamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) instead of triethanolamine, acidic urethane urea-based resin and low-molecular-weight amine compound are used in the same manner as in the production of urethane urea-based resin aqueous dispersion 1. An aqueous dispersion containing dimethylethanolamine (30% active ingredient) was obtained. This is referred to as urethane urea-based resin water dispersion 2.

Except for using triethylamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) instead of triethanolamine, an acidic urethane urea resin and triethylamine as a low molecular weight amine compound are used in the same manner as in the production of the urethane urea resin aqueous dispersion 1. An aqueous dispersion containing (30% active ingredient) was obtained. This is referred to as urethane urea-based resin water dispersion 3.

<Manufacturing of (meth) acrylic resin aqueous dispersion 1>
Monomer mixture A consisting of 95 parts by mass of methyl methacrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 5 parts by mass of butyl acrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added to 40 parts by mass of ion-exchanged water with Emulgen 1135S-70 (manufactured by Kao Co., Ltd.). , Nonionic non-reactive surfactant) in 2 parts by mass and Emulsogen EPA073 (manufactured by Clariant Japan Co., Ltd., anionic non-reactive surfactant) in 1.5 parts by mass in an aqueous solution and stirred. The emulsified monomer composition was prepared in 1. Next, 173 parts by mass of ion-exchanged water and 1 part by mass of Emulsogen EPA073 were charged into a four-necked flask, and the mixture was stirred and dissolved to raise the temperature to 73 ° C. 5% of the above emulsified monomer composition is added thereto and stirred to add a 3% aqueous solution of potassium persulfate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (hereinafter sometimes referred to as "3% potassium persulfate"). 1.3 parts by mass was added and initial polymerization was carried out. Then, while maintaining the temperature at 80 ° C., 5.3 parts by mass of 3% potassium persulfate and the remaining emulsified monomer composition were added dropwise over 3 hours and 30 minutes to allow the polymerization reaction to proceed. After completion of the dropping, the reaction was carried out for 60 minutes to complete the first-stage polymerization. Next, a monomer mixture B consisting of 2.8 parts by mass of methyl methacrylate and 2.4 parts by mass of methacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added at the same time as 0.87 parts by mass of 3% potassium persulfate in the second stage. The polymerization of was started. After completion of the dropping, the pH was adjusted to 8 with dimethylethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.), and then the reaction was aged for 1 hour. Then, after cooling to 50 ° C. and continuing stirring for another hour, ion-exchanged water was added to adjust the solid content to 30% by mass, and acidic (meth) acrylic resin and dimethylethanolamine as a low molecular weight amine compound were added. An aqueous dispersion containing (30% active ingredient) was obtained. This is designated as the (meth) acrylic resin aqueous dispersion 1.

<Manufacturing of Urethane Resin Solution 1 and Urethane Resin Water Dispersion 1>
Diethanolamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was charged in a four-necked flask by 105.1 parts by mass, and the temperature was raised to 110 ° C. while agitating nitrogen gas and stirring. To this, 72.1 parts by mass of acrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise over 30 minutes. The Michael addition reaction was completed at 110 ° C. for 2 hours to obtain a liquid diol. In another four-necked flask, 35.4 parts by mass of the diol solution obtained above and 15.2 parts by mass of propylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as other diol components were charged as a tin catalyst. 0.15 parts by mass of dibutyltin dilaurate (manufactured by Tokyo Fine Chemical Industries, Ltd.) was added, and the temperature was raised to 78 ° C. while agitating and stirring nitrogen gas. Then, a mixture of 67.3 parts by mass of hexamethylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 118.1 parts by mass of methyl ethyl ketone (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes. After the dropping, the mixture was reacted under reflux at a temperature of 78 ° C. to 80 ° C. for 24 hours and then cooled to obtain a solution of an acidic urethane resin having a solid content of 50% by mass. This is referred to as urethane-based resin solution 1.

80 parts by mass of ion-exchanged water was added to 100 parts by mass of the above acidic urethane resin solution (urethane resin solution 1), and the pH was adjusted to 8 with dimethylethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.). Then, methyl ethyl ketone was removed at 50 ° C. and under reduced pressure. Ion-exchanged water was added thereto to adjust the solid content to 30% by mass to obtain an acidic urethane resin and an aqueous dispersion (active ingredient 30%) containing dimethylethanolamine as a low molecular weight amine compound. This is referred to as urethane-based resin water dispersion 1.

<Manufacturing of (meth) acrylic resin solutions a to f>
The (meth) acrylic resin solutions a to f were produced as follows.

Production of (Meta) Acrylic Resin Solution a 200 parts by mass of Exepearl M-OL (Methyl Oleate, manufactured by Kao Corporation) is placed in a four-necked flask, and the temperature is raised to 110 ° C. while agitating nitrogen gas and stirring. did. Next, while keeping the temperature at 110 ° C., 50 parts by mass of behenyl methacrylate (manufactured by NOF Corporation), 20 parts by mass of dodecyl methacrylate (manufactured by Kao Co., Ltd.), and 15 parts by mass of acetoacetoxyethyl methacrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 50 parts by mass of Exepearl M-OL and perbutyl O (manufactured by NOF Corporation, t-butylperoxy2-ethyl) in 100 parts by mass of a monomer mixture in which 15 parts by mass and 15 parts by mass of dimethylacrylamide (manufactured by KJ Chemicals Co., Ltd.) are mixed. The mixture mixed with hexanoate) was added dropwise over 3 hours. Then, after stirring for 1 hour while keeping the temperature at 110 ° C., perbutyl O was added and the mixture was further stirred for 1 hour while keeping the temperature at 110 ° C. Exepearl M-OL was added so that the solid content was 40% by mass, and a (meth) acrylic resin solution a was obtained.

(Meta) Production of Acrylic Resin Solution b In the same manner as in the production of methacrylic resin solution a, except that 15 parts by mass of N-vinylpyrrolidone (manufactured by Nippon Catalyst Co., Ltd.) was used instead of 15 parts by mass of dimethylacrylamide. A (meth) acrylic resin solution b having a solid content of 40% by mass was obtained.

(Meta) Production of Acrylic Resin Solution c Solid content in the same manner as in the production of methacrylic resin solution a, except that 15 parts by mass of acryloyl morpholine (manufactured by KJ Chemicals Co., Ltd.) was used instead of 15 parts by mass of dimethylacrylamide. A 40% by mass (meth) acrylic resin solution c was obtained.

Production of (Meta) Acrylic Resin Solution d A methacrylic resin solution other than using 15 parts by mass of M-90G (methoxypolyethylene glycol # 400 methacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) instead of 15 parts by mass of dimethylacrylamide. In the same manner as in the production of a, a (meth) acrylic resin solution d having a solid content of 40% by mass was obtained.

(Meta) Production of Acrylic Resin Solution e Solid in the same manner as in the production of methacrylic resin solution a, except that Exol D130 (manufactured by Exxon Mobile Co., Ltd., petroleum hydrocarbon solvent) was used instead of Exepearl M-OL. A (meth) acrylic resin solution e of 40% by mass was obtained.

(Meta) Production of Acrylic Resin Solution f Same as the production of methacrylic resin solution a, except that 15 parts by mass of dimethylacrylamide is not used and the amount of acetoacetoxyethyl methacrylate is changed from 15 parts by mass to 30 parts by mass. A (meth) acrylic resin solution f having a solid content of 40% by mass was obtained.

<Ink manufacturing>
The inks of Examples 1 to 11 and Comparative Examples 1 to 4 were produced as follows.

1. 1. Production of Dispersant-Containing Liquids 1 to 8 and 11 to 13 A non-aqueous solvent is mixed with a (meth) acrylic resin solution or an acidic polymer in the amounts shown in EM1 to EM9 and EM11 to EM13 in Tables 1 to 3. A mixture for a continuous phase (oil phase) was prepared. An aqueous dispersion containing the acidic resins and low molecular weight amine compounds shown in EM1 to EM9 and EM11 to EM13 in Tables 1 to 3 as a mixture for a dispersed phase (aqueous phase) in the mixture for a continuous phase prepared in this manner. Ultrasonic homogenizer "Ultrasonic phaseser VC-750" under ice-cooling while dropping urethane urea-based resin aqueous dispersions 1 to 3, (meth) acrylic resin aqueous dispersion 1 or urethane-based resin aqueous dispersion 1). (Manufactured by Sonics) was irradiated for 10 minutes to obtain a water-in-oil (W / O) type emulsion (EM1-9, 11-13).
In EM9, the aqueous phase and the oil phase could not be separated to obtain a water-in-oil emulsion, so the following operation was not performed.
Each of the obtained water-in-oil emulsions (EM1-8, 11-13) is depressurized at a vacuum degree of 100 hPa in a water bath at 80 ° C. using a rotary evaporator "RE601" (manufactured by Yamato Chemical Co., Ltd.) to form an emulsion. The treatment was carried out for 1 hour per 100 g, and the water in the emulsion was removed to obtain a dispersant dispersion as a resin particle dispersion having a solid content of 40%. The water removal rate was approximately 100% by mass. Dispersant dispersions obtained by removing water in this way using EM1 to 8 and 11 to 13 are used as dispersant-containing liquids 1 to 8 and 11 to 13 (both have a solid content of 40%) (hereinafter, solid content is 40%). , Each of which may be referred to as dispersants 1 to 8 and 11 to 13).

2. Production of Dispersant-Containing Liquid 10 A non-aqueous solvent and a (meth) acrylic resin solution a were mixed at the blending amounts shown in ML10 in Table 3. An acidic resin solution (urethane-based resin solution 1) was added thereto in an amount shown in ML10 in Table 3 to obtain a mixed solution. This mixed solution is referred to as ML10. About this ML10, the pressure was reduced at a vacuum degree of 100 hPa in a water bath at 60 ° C. with a rotary evaporator "RE601" (manufactured by Yamato Chemical Co., Ltd.) to remove methyl ethyl ketone, and a dispersant-containing liquid 10 (solid content 40%) (solid content 40%). Hereinafter, it may be referred to as a dispersant 10). The "amount of water in the water-in-oil emulsion" in Tables 2 and 3 indicates the amount of water in the mixed solution ML10 for ML10.

3. 3. Production of Ink In the blending amounts shown in Tables 4 and 5, the pigment was mixed with a dispersant-containing liquid and a non-aqueous solvent, dispersed by a bead mill "Dynomill Multi LAB" (manufactured by Simmal Enterprises Co., Ltd.), and in Examples. Inks 1 to 11 and Comparative Examples 1, 3 and 4 were obtained. In Comparative Example 2, the pigments aggregated and ink could not be obtained. Therefore, the following evaluation was not performed for Comparative Example 2.

<Evaluation>
The inks of Examples 1 to 11 and Comparative Examples 1, 3 and 4 obtained as described above were evaluated according to the following evaluation methods. The results are shown in Tables 4 and 5.

1. 1. Ink was introduced into the agglutinating inkjet printer "Orphis GD9630" (manufactured by Riso Kagaku Corporation), and the ink was left to circulate in the ink path for 2 weeks. 1 ml of ink was extracted from the ink path and observed with an optical microscope, and agglomerates were evaluated according to the following evaluation criteria.

(Evaluation criteria)
A: Aggregates are not observed B: Aggregates are observed

2. Storage stability First, the viscosity of the ink immediately after the ink was prepared was measured.
Next, the ink was placed in a closed container and left at 70 ° C. for 4 weeks. Then, the ink was sampled and the ink viscosity was measured.
The ink viscosity was the viscosity at 23 ° C., and was measured using a rheometer AR-G2 (manufactured by TA Instruments Japan Co., Ltd.) at a cone angle of 2 ° and a diameter of 40 mm.
From the ink viscosity immediately after production and the ink viscosity before and after leaving for 4 weeks, the viscosity change rate was determined by the following formula, and the storage stability was evaluated according to the following criteria.
Viscosity change rate (%) = [(Ink viscosity after leaving for 4 weeks x 100) / (Viscosity immediately after production)] -100 (%)
(Evaluation criteria)
A: Absolute value of viscosity change rate is less than 5% B: Absolute value of viscosity change rate is 5% or more

3. 3. Scratch resistance Each ink was loaded into an inkjet printer "Orphis GD9630" (manufactured by Riso Kagaku Corporation), and a solid image was printed on plain paper "Ideal Paper Multi" (manufactured by Riso Kagaku Corporation). Twenty-four hours after printing, the area including the solid image portion of the surface having the solid image of the printed matter is rubbed with a white cotton cloth 5 times in 5 seconds using a clock meter (“CM-1” manufactured by Atlas Electric Device Co., Ltd.) to obtain an image. The surrounding pollution was evaluated according to the following criteria.

(Evaluation criteria)
AA: Almost no contamination around the image A: Slight contamination around the image B: Contamination around the image

As shown in each table, no agglomerates were observed in the evaluation of agglomerates in the inks of each example. On the other hand, it is selected from the group consisting of Comparative Example 1 in which the dispersant 10 not using the low molecular weight amine compound is used, the group represented by the general formula (1) and the group represented by the general formula (2). Comparative Example 3 in which the dispersant 11 using the acidic polymer 1 was used instead of the (meth) acrylic resin containing at least one group, and the groups represented by the general formula (1) and the general formula (2). In Comparative Example 4 in which the dispersant 13 using the (meth) acrylic resin containing none of the groups represented by) was used, agglomerates were observed in the evaluation of the agglomerates.
In Examples 1 to 3 and 6 to 11 in which any of the dispersants 1 to 3 and 6 to 8 in which an acidic urethane urea resin was used as the acidic resin was used, the scratch resistance was improved.
The inks of Examples 1 to 11 all showed good storage stability.

Claims (6)

With pigments
A (meth) acrylic containing an acidic resin, a low molecular weight amine compound, and at least one group selected from the group consisting of a group represented by the following general formula (1) and a group represented by the following general formula (2). Dispersants formed by based resins and
Oil-based inkjet ink containing non-aqueous solvent.

(In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring. General formula (2) In, R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.) The oil-based inkjet ink according to claim 1, wherein the low molecular weight amine compound contains an alkanolamine. The oil-based inkjet ink according to claim 1 or 2, wherein the acidic resin contains at least one selected from the group consisting of an acidic (meth) acrylic resin and an acidic urethane-based resin. The oil-based inkjet ink according to claim 3, wherein the acidic resin contains an acidic urethane urea resin. A continuous containing a non-aqueous solvent and a (meth) acrylic resin containing at least one group selected from the group consisting of a group represented by the following general formula (1) and a group represented by the following general formula (2). A step of obtaining a water-in-oil emulsion containing a phase and a dispersed phase containing water, an acidic water-dispersible resin and a low-molecular-weight amine compound.
A step of removing water from the water-in-oil emulsion to obtain a dispersant dispersion, and
The step of mixing the dispersant dispersion and the pigment and dispersing the pigment is included.
A method for manufacturing oil-based inkjet ink.

(In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring. General formula (2) In, R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.) A continuous containing a non-aqueous solvent and a (meth) acrylic resin containing at least one group selected from the group consisting of a group represented by the following general formula (1) and a group represented by the following general formula (2). A step of obtaining a water-in-oil emulsion containing a phase and a dispersed phase containing water, an acidic water-dispersible resin and a low-molecular-weight amine compound.
Including a step of removing water from the water-in-oil emulsion.
Dispersant manufacturing method.

(In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent, and R ¹ and R ² may be bonded to each other to form a ring. General formula (2) In, R ³ represents a substituent, R ⁴ represents a hydrogen atom or a substituent, and R ³ and R ⁴ may be bonded to each other to form a ring.)