JP2022102920A - Water-in-oil emulsion ink - Google Patents

Abstract

To provide a water-in-oil emulsion ink that gives a printed material having high fixability even when printed on a highly water-absorbable print medium, while the water-in-oil emulsion ink has high storage stability, and a method for producing the water-in-oil emulsion ink.SOLUTION: A water-in-oil emulsion ink has an aqueous phase in an oil phase, the aqueous phase containing a pigment, a polymer dispersant A, and a polymer particle B free of a pigment, and the oil phase containing a water-insoluble organic solvent and an emulsifier. There is also provided a method for producing the water-in-oil emulsion ink.SELECTED DRAWING: None

Description

The present invention relates to a water-in-oil emulsion ink and a method for producing the water-in-oil emulsion ink.

The inkjet recording method is a recording method in which ink droplets are directly ejected from a fine nozzle and adhered to a print medium to obtain a printed matter on which characters and images are recorded. This method has the advantages of being easy to make full-color, inexpensive, and non-contact with the printed matter, so it has begun to be applied not only to consumer printing for general consumers but also to commercial printing and industrial printing in recent years. There is.
Conventionally, as the ink for inkjet recording, a water-based ink using a pigment or a dye as a colorant has been used. However, when printing on plain paper using water-based ink, the print density is high because the water absorption of the plain paper is high, but the printed matter is curled due to the expansion of the plain paper fibers due to the water contained in the water-based ink. There is a problem of deformation.
Further, in the fields of commercial printing and industrial printing, high-speed printing is required, and in order to cope with this high-speed printing, a printing machine adopting a line head type inkjet recording method has been developed, and oil-based pigment ink is used. When printing on plain paper using an oil-based pigment ink, deformation of the printed matter can be reduced, but there is a problem that the ink penetrates into the inside of the printed matter and the print density of the printed matter is lowered.
Therefore, studies have been made on using a water-in-oil (W / O) type emulsion ink.
For example, Patent Document 1 describes a water-in-oil emulsion ink composed of an oil phase and an aqueous phase for the purpose of providing an emulsion ink for inkjet having excellent high-speed fixing property and scratch resistance. Emulsion inks for inkjet are disclosed, which are modified pigments containing water and a colorant, wherein the colorant contains a polymer.

JP-A-2015-189859A

The water-in-oil emulsion ink has a continuous phase as an oil phase, and the water phase is emulsified in the oil phase. When a pigment is contained as a colorant in the aqueous phase, the aqueous phase tends to aggregate, so that good storage stability is required.
Further, when printing is performed on a highly water-absorbent printing medium such as plain paper using a water-in-oil emulsion ink, the pigment remains on the surface layer of the printing medium, so that the pigment is sufficiently fixed to the highly water-absorbent printing medium. It turned out that sex could not be obtained.
The present invention is a water-in-oil emulsion ink and a water-in-oil emulsion capable of obtaining a printed matter having excellent fixing property even when printed on a print medium having high water absorption while having good storage stability, and the water-in-oil emulsion. An object of the present invention is to provide a method for producing ink.

The present inventor has a water-in-oil emulsion ink containing an aqueous phase in the oil phase, wherein the aqueous phase contains a pigment, a polymer dispersant, and polymer particles containing no pigment, thereby solving the above-mentioned problems. I found that it could be solved. That is, the present invention provides the following [1] and [2].
[1] A water-in-oil emulsion ink having an aqueous phase in the oil phase.
The aqueous phase contains a pigment, a polymer dispersant A, and polymer particles B containing no pigment.
A water-in-oil emulsion ink in which the oil phase contains a water-insoluble organic solvent and an emulsifier.
[2] The method for producing a water-in-oil emulsion ink according to the above [1], which comprises the following step I.
Step I: Includes an aqueous phase component containing an aqueous pigment dispersion in which the pigment is dispersed in an aqueous medium with a polymer dispersant A, an aqueous dispersion of polymer particles B containing no pigment, and a water-insoluble organic solvent and emulsifier. A process of mixing and emulsifying an oil phase component to obtain a water-in-oil emulsion ink.

The present invention is a water-in-oil emulsion ink and a water-in-oil emulsion capable of obtaining a printed matter having excellent fixing property even when printed on a print medium having high water absorption while having good storage stability, and the water-in-oil emulsion. A method for producing an ink can be provided.

[Water-in-oil emulsion ink]
The water-in-oil emulsion ink of the present invention (hereinafter, also referred to as "emulsion ink") is a water-in-oil emulsion ink having an aqueous phase in the oil phase, and the aqueous phase is a pigment or a polymer dispersant A. , And the pigment-free polymer particles B, the oil phase containing a water-insoluble organic solvent and an emulsifier.
In the present invention, the aqueous phase dispersed in the oil phase contains a pigment dispersed in the polymer dispersant A and polymer particles B containing no pigment.

The water-in-oil emulsion ink of the present invention has a special effect of having good storage stability and excellent fixing property even when printed on a printing medium having high water absorption. The reason is not clear, but it can be considered as follows.
In the present invention, since the pigment is dispersed in the aqueous phase by the polymer dispersant, the dispersion stability of the pigment can be improved, and further, the polymer particles containing no pigment are stably contained in the aqueous phase. It is considered that the dispersion stability in the aqueous phase, which is the dispersed phase, is improved, and the whole system of the emulsion ink can be stabilized probably because the coalescence of the aqueous phases is suppressed. As a result, while having good storage stability when the emulsion ink is stored at a high temperature for a long period of time, the function as a fixing aid by the polymer particles containing no pigment contained in the aqueous phase is exhibited, and the fixing property is exhibited. Is considered to be able to be expressed.

<Water phase>
The aqueous phase contains a pigment, a polymer dispersant A, and polymer particles B containing no pigment from the viewpoint of improving storage stability and fixability.

(Pigment)
The pigment according to the present invention may be either an inorganic pigment or an organic pigment, and a lake pigment or a fluorescent pigment may also be used. In addition, if necessary, they can be used in combination with extender pigments.
Specific examples of the inorganic pigment include carbon black, titanium oxide, iron oxide, red iron oxide, metal oxides such as chromium oxide, and pearl luster pigments. Especially for black ink, carbon black is preferable.
The type of carbon black is not particularly limited, and examples thereof include furnace black, lamp black, acetylene black, and channel black.

Specific examples of organic pigments include azo pigments such as azo lake pigments, insoluble mono azo pigments, insoluble disazo pigments, and chelate azo pigments; phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, and isoind. Examples thereof include polycyclic pigments such as linone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, and slen pigments.
The hue is not particularly limited, and any chromatic pigment such as yellow, magenta, cyan, blue, red, orange, and green can be used.
Specific examples of preferable organic pigments include C.I. I. Pigment Yellow, C.I. I. Pigment Red, C.I. I. Pigment Orange, C.I. I. Pigment Violet, C.I. I. Pigment Blue, and C.I. I. One or more product numbers selected from Pigment Green can be mentioned.
Examples of the extender pigment include silica, calcium carbonate, talc and the like.
The pigment may be used alone or in combination of two or more.

(Polymer Dispersant A)
The pigment in the emulsion ink of the present invention is a polymer dispersant A in the aqueous phase from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and the fixability. Dispersed by.

The polymer dispersant A according to the present invention is not particularly limited as long as it has at least a pigment-dispersing ability, but from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase and improving the storage stability, and From the viewpoint of improving the fixability, it preferably contains an acid group.
As the acid group of the polymer dispersant A, a carboxy group (-COOM), a sulfonic acid group (-SO ₃ M), a phosphoric acid group (-OPO ₃ M ₂ ) and the like are dissociated to release hydrogen ions. Examples thereof include groups exhibiting acidity, or their dissociated ionic forms (-COO- ^, -SO _3- , -OPO ₃ ^2- , -OPO ₃ ^- M) ^and the like. In the above chemical formula, M represents a hydrogen atom, an alkali metal, ammonium or an organic ammonium. Among these, a carboxy group (-COMM) is preferable from the same viewpoint as described above.

At least a part of the acid group of the polymer dispersant A is neutralized from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase, improving the storage stability, and improving the fixability. Is preferable.
Examples of the neutralizing agent used for neutralizing the polymer dispersant A include alkali metal hydroxides and ammonia. Among them, alkali metal hydroxide is preferable, and sodium hydroxide and more are preferable, from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase, improving the storage stability, and improving the fixability. One or more selected from potassium hydroxide.
From the same viewpoint as described above, the degree of neutralization is preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 40 mol% or more, still more preferably 45 mol% or more, and preferably. It is 80 mol% or less, more preferably 70 mol% or less, still more preferably 60 mol% or less.
Specifically, the degree of neutralization (mol%) can be obtained by the following equation.
Degree of neutralization (mol%) = [{addition mass of neutralizer (g) / equivalent of neutralizer} / [{acid value of polymer dispersant A (mgKOH / g) x mass of polymer dispersant A (g) )} / (56.1 x 1,000)]] x 100

[Polymer (a)]
The polymer dispersant A according to the present invention is a non-crosslinked polymer (hereinafter referred to as “) from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and the fixability. It may also be a non-crosslinked polymer (a) ”or“ polymer (a) ”. The polymer (a) preferably contains an acid group from the same viewpoint as described above.

The acid value of the polymer (a) is preferably 70 mgKOH / g or more, more preferably 100 mgKOH / g or more, still more preferably 100 mgKOH / g or more, from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase and improving the storage stability. Is 150 mgKOH / g or more, more preferably 200 mgKOH / g or more, still more preferably 220 mgKOH / g or more, and preferably 320 mgKOH / g or less, more preferably 300 mgKOH / g or less, still more preferably 280 mgKOH / g or less. , More preferably 260 mgKOH / g or less. When the acid value is in the above range, the amount of the acid group can be sufficient to ensure the dispersion stability of the pigment. It is also preferable from the viewpoint of the balance between the affinity between the polymer (a) and water and the interaction between the polymer (a) and the pigment.
The acid value of the polymer (a) can be measured by the method described in Examples.
Further, the acid value of the polymer (a) can be calculated from the mass ratio of the constituent monomers.

Examples of the polymer (a) include polyester-based resin, polyurethane-based resin, vinyl-based resin and the like. Among them, a vinyl-based resin is preferable, and a vinyl-based resin containing a structural unit derived from a carboxy group-containing monomer and a structural unit derived from a hydrophobic monomer is more preferable. The vinyl-based resin may further contain a structural unit derived from a nonionic monomer.

[Monomer containing carboxy group]
The carboxy group-containing monomer is preferably used as a monomer component of a vinyl resin from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase, improving the storage stability, and improving the fixability.
Examples of the carboxy group-containing monomer include (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethylsuccinic acid and the like, but (meth) acrylic acid is preferable. , More preferably acrylic acid.
As used herein, the term "(meth) acrylic acid" means at least one selected from acrylic acid and methacrylic acid.
The carboxy group-containing monomer may be used alone or in combination of two or more.

[Hydrophobic monomer]
The hydrophobic monomer is a vinyl resin from the viewpoint of improving the adsorptivity of the polymer to the pigment, improving the dispersion stability of the pigment in the aqueous phase, improving the storage stability, and improving the fixability. It is preferable to use it as a monomer component of.
As used herein, the term "hydrophobic" means that when the monomer is dissolved in 100 g of ion-exchanged water at 25 ° C. until it is saturated, the amount of the monomer dissolved is less than 10 g. The dissolved amount of the hydrophobic monomer is preferably 5 g or less, more preferably 1 g or less, from the viewpoint of the adsorptivity of the polymer to the pigment.
Examples of the hydrophobic monomer include an aromatic group-containing monomer and a (meth) acrylate having a hydrocarbon group derived from an aliphatic alcohol.
As used herein, "(meth) acrylate" is at least one selected from acrylates and methacrylates.
The hydrophobic monomer may be used alone or in combination of two or more.

The aromatic group-containing monomer is preferably a vinyl monomer having an aromatic group having 6 or more and 22 or less carbon atoms, which may have a substituent containing a heteroatom, and more preferably a styrene-based monomer and an aromatic. At least one selected from group-containing (meth) acrylates. The molecular weight of the aromatic group-containing monomer is preferably less than 500.
The styrene-based monomer is preferably at least one selected from styrene, α-methylstyrene, 2-methylstyrene, vinyltoluene, and divinylbenzene, and more preferably at least one selected from styrene and α-methylstyrene. Is.
The aromatic group-containing (meth) acrylate is preferably at least one selected from phenyl (meth) acrylate, benzyl (meth) acrylate, and phenoxyethyl (meth) acrylate, and more preferably benzyl (meth) acrylate. ..

The (meth) acrylate having a hydrocarbon group derived from an aliphatic alcohol preferably has a hydrocarbon group derived from an aliphatic alcohol having 1 or more and 22 or less carbon atoms. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, (Meta) acrylates having a linear alkyl group such as stearyl (meth) acrylate; isopropyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, isopentyl (meth) acrylate, isooctyl (meth) acrylate, (Meta) acrylate having a branched chain alkyl group such as isodecyl (meth) acrylate, isododecyl (meth) acrylate, isostearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; alicyclic alkyl such as cyclohexyl (meth) acrylate. Examples thereof include (meth) acrylate having a group.

In the present invention, a hydrophobic macromonomer may be used as the hydrophobic monomer constituting the vinyl resin.
The macromonomer is a compound having a polymerizable functional group at one end and having a number average molecular weight of 500 or more and 100,000 or less, and is used as a monomer component of a vinyl resin from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase. Can be used. As the polymerizable functional group present at one end, an acryloyloxy group or a methacryloyloxy group is preferable, and a methacryloyloxy group is more preferable.
The number average molecular weight of the macromonomer is preferably 1,000 or more and 10,000 or less. The number average molecular weight is measured by a gel permeation chromatography method using chloroform containing 1 mmol / L dodecyldimethylamine as a solvent, using polystyrene as a standard substance.
As the macromonomer, an aromatic group-containing monomer-based macromonomer and a silicone-based macromonomer are preferable, and an aromatic group-containing monomer-based macromonomer is more preferable, from the viewpoint of dispersion stability of the pigment in the aqueous phase.
Examples of the aromatic group-containing monomer constituting the aromatic group-containing monomer-based macromonomer include the aromatic group-containing monomer described in the above-mentioned hydrophobic monomer, and styrene and benzyl (meth) acrylate are preferable, and styrene is more preferable. ..
The macromonomer may be used alone or in combination of two or more.
Specific examples of commercially available styrene-based macromonomers include AS-6 (S), AN-6 (S), HS-6 (S) (trade name of Toagosei Co., Ltd.) and the like.
Examples of the silicone-based macromonomer include organopolysiloxane having a polymerizable functional group at one end.

The hydrophobic monomer is preferably aromatic from the viewpoint of improving the adsorptivity of the polymer to the pigment, improving the dispersion stability of the pigment in the aqueous phase, improving the storage stability, and improving the fixability. One or more selected from a group-containing monomer, a (meth) acrylate having a hydrocarbon group derived from an aliphatic alcohol, and an aromatic group-containing monomer-based macromonomer, and more preferably an aromatic group-containing monomer and an aliphatic alcohol. It is one or more selected from (meth) acrylates having a derived hydrocarbon group, more preferably an aromatic group-containing monomer, and even more preferably selected from a styrene-based monomer and an aromatic group-containing (meth) acrylate. One or more.

[Nonionic monomer]
The nonionic monomer can be used as a monomer component of a vinyl resin from the viewpoint of dispersion stability of the pigment in the aqueous phase.
Examples of the nonionic monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 3-hydroxypropyl (meth) acrylate; polypropylene glycol (n = 2 to 30, n is the average molar addition of oxypropylene group). The number is shown. The following n indicates the average number of moles of the oxyalkylene group added.) Polyalkylene glycol (meth) acrylate such as (meth) acrylate and polyethylene glycol (n = 2 to 30) (meth) acrylate; methoxy. Alkoxypolyalkylene glycol (meth) acrylates such as polyethylene glycol (n = 1 to 30) (meth) acrylate; phenoxy (ethylene glycol / propylene glycol copolymerization) (n = 1 to 30, ethylene glycol in it: n = 1). To 29) (meth) acrylate and the like can be mentioned. Of these, polypropylene glycol (n = 2 to 30) (meth) acrylate, alkoxypolyalkylene glycol (meth) acrylate, and phenoxy (ethylene glycol / propylene glycol copolymer) (meth) acrylate are preferable.
The nonionic monomer may be used alone or in combination of two or more.
Specific examples of commercially available nonionic monomers include Shin Nakamura Chemical Industry Co., Ltd.'s NK Ester M-20G, 40G, 90G, 230G, etc., and NOF Corporation's Blemmer PE-90, 200. , 350, etc., Blemmer PME-100, 200, 400, etc., Blemmer PP-500, 800, 1000, etc., Blemmer AP-150, 400, 550, etc., Blemmer 50 PEP-300, 50 POEP-800B, 43 PAPE-600B and the like can be mentioned.

As described above, the polymer (a) according to the present invention is preferably derived from a structural unit derived from one or more carboxy group-containing monomers selected from acrylic acid and methacrylic acid, an aromatic group-containing monomer, and an aliphatic alcohol. A vinyl-based resin containing a (meth) acrylate having a hydrocarbon group and a structural unit derived from one or more hydrophobic monomers selected from aromatic group-containing monomer-based macromonomers, and further a structural unit derived from a nonionic monomer. Although it may be a vinyl-based resin containing, acrylic acid and acrylic acid are more preferable from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase, improving the storage stability, and improving the fixability. Derived from one or more hydrophobic monomers selected from constituent units derived from one or more carboxy group-containing monomers selected from methacrylic acid and (meth) acrylates having hydrocarbon groups derived from aromatic group-containing monomers and aliphatic alcohols. It is a vinyl-based resin containing the constituent units of, and more preferably, a constituent unit derived from one or more carboxy group-containing monomers selected from acrylic acid and methacrylic acid, and a styrene-based monomer and an aromatic group-containing (meth) acrylate. A vinyl-based resin containing a structural unit derived from one or more hydrophobic monomers selected from the above.

(Content of constituent units derived from each monomer in vinyl resin)
The content of the constituent units derived from each monomer in the vinyl resin is as follows from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase, improving the storage stability, and improving the fixability. Is.
The content of the structural unit derived from the carboxy group-containing monomer in the vinyl resin is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, still more preferably 20% by mass or more. Yes, and it is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less, still more preferably 40% by mass or less.
The content of the structural unit derived from the hydrophobic monomer in the vinyl resin is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, still more preferably 60% by mass or more. And, preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less.
When the vinyl-based resin contains a structural unit derived from a macromonomer, the content of the structural unit derived from the macromonomer in the vinyl-based resin is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferable. Is 15% by mass or more, and is preferably 35% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less.
When the vinyl-based resin contains a structural unit derived from a nonionic monomer, the content of the structural unit derived from the nonionic monomer in the vinyl-based resin is preferably 3% by mass or more, more preferably 5% by mass or more. It is more preferably 7% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less.
The content of the structural unit derived from each monomer in the above vinyl resin can be measured by analysis such as NMR. Further, the preferable range of the content (content as an unneutralized amount) of each monomer in the raw material monomer at the time of producing the vinyl resin is preferably the content of the constituent unit derived from each monomer in the vinyl resin. Can be considered the same as the range.

The total content of the structural unit derived from the carboxy group-containing monomer and the structural unit derived from the hydrophobic monomer in the vinyl resin is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more. It is still more preferably 90% by mass or more, preferably 100% by mass or less, still more preferably substantially 100% by mass, and even more preferably 100% by mass.
Mass ratio of the content of the structural unit derived from the carboxy group-containing monomer in the vinyl resin to the content of the structural unit derived from the hydrophobic monomer [Content of the structural unit derived from the carboxy group-containing monomer / Composition derived from the hydrophobic monomer The unit content] is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, still more preferably 0.4 or more, and preferably 2 or less, more preferably. Is 1.5 or less, more preferably 1 or less, still more preferably 0.9 or less, still more preferably 0.8 or less, still more preferably 0.7 or less, still more preferably 0.5 or less.

The vinyl-based resin is produced by copolymerizing a raw material monomer by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Of these polymerization methods, the solution polymerization method is preferable. Further, the mode of chaining the polymerization monomers is not limited, and any polymerization mode such as random, block, and graft may be used.

The weight average molecular weight of the vinyl resin is preferably 2,000 or more, more preferably 5,000 or more, still more preferably 7,000 or more, and preferably 100,000 or less, more preferably 50,000 or less. It is more preferably 30,000 or less, still more preferably 20,000 or less. When the weight average molecular weight of the vinyl resin is in the above range, the adsorption force to the pigment is sufficient and the dispersion stability can be exhibited.
The weight average molecular weight of the vinyl resin is measured by the method described in Examples.

[Crosslinked polymer (a')]
In the present invention, the pigment is dispersed by the polymer dispersant A from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and the fixability. The polymer dispersant A preferably contains a crosslinked structure.
The polymer dispersant A has a crosslinked structure preferably crosslinked with a crosslinking agent from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and the fixability. A polymer containing a crosslink or a polymer having a self-crosslinking structure into which a crosslinkable group is introduced, more preferably a polymer having a crosslinked structure crosslinked with a crosslinking agent, and still more preferably a crosslinking of the above-mentioned non-crosslinking polymer (a). It is a crosslinked polymer (a') crosslinked with an agent.
That is, the crosslinked polymer (a') has a structure derived from a crosslinking agent in addition to the structural unit derived from the monomer constituting the polymer (a).
In the present invention, the crosslinked polymer (a') is firmly adsorbed or immobilized on the pigment surface as the polymer dispersant A, and the aggregation of the pigment in the aqueous phase, particularly the depletion aggregation, is suppressed, and the pigment in the aqueous phase is suppressed. Since the dispersion stability is improved, the swelling of the polymer is suppressed, and the entire system of the emulsion ink can be stabilized, even when the polymer particles B containing no pigment are further contained in the aqueous phase, the aqueous phase contains the polymer particles B. It is considered that the storage stability can be improved.

[Crosslinking agent]
From the viewpoint of reactivity with the polymer (a), the cross-linking agent has a water content (mass ratio) of preferably 50% or less, more preferably 40% or less, still more preferably 35% or less. The water content% (mass ratio) means the dissolution rate (%) when 10 parts by mass of the cross-linking agent is dissolved in 90 parts by mass of water at room temperature of 25 ° C.

The cross-linking agent is preferably a polyfunctional compound, and when the polymer (a) contains an acid group, the cross-linking functional group of the polyfunctional compound can react with the acid group of the polymer (a) to form a covalent bond. Is preferable. The covalent bond is preferably one or more selected from an ester bond, a thioester bond, an amide bond, an amino bond, an ether bond, a thioether bond, a carbonyl bond, a thiocarbonyl bond and a sulfonyl bond, and more preferably an ester bond. One or more selected from thioester bonds and amide bonds. The crosslinkable functional group of the polyfunctional compound is not particularly limited as long as it can form the above-mentioned covalent bond.
The molecular weight of the cross-linking agent is preferably 120 or more, more preferably 150, from the viewpoints of easiness of reaction, improvement of dispersion stability of the pigment in the aqueous phase, improvement of storage stability, and improvement of fixability. Above, it is more preferably 200 or more, and preferably 2,000 or less, more preferably 1,500 or less, still more preferably 1,000 or less.

The crosslinkable functional group is preferably one or more selected from an epoxy group, an isocyanate group, an aziridino group, an amino group and an oxazoline group, and more preferably an epoxy group. The concept of epoxy group includes glycidyl group. That is, the cross-linking agent is preferably a polyfunctional epoxy compound, more preferably a compound having two or more epoxy groups in the molecule, and even more preferably a compound having two or more glycidyl ether groups, from the viewpoint of cross-linking efficiency. Is a polyhydric alcohol polyglycidyl ether compound having a hydrocarbon group having 3 or more and 8 or less carbon atoms.
When the cross-linking agent is a polyfunctional epoxy compound, the epoxy equivalent of the cross-linking agent is preferably 90 or more, more preferably 100 or more, still more preferably 110 or more, and preferably 300 or less, more preferably 200 or less. , More preferably 150 or less.
When the cross-linking agent is a polyfunctional epoxy compound, the number of epoxy groups of the cross-linking agent is a viewpoint of efficiently carrying out a cross-linking reaction, improving the dispersion stability of the pigment in the aqueous phase, and improving the storage stability. And, from the viewpoint of improving the fixability, it is 2 or more per molecule, and preferably 6 or less per molecule, more preferably 4 or less, and further preferably 3 or less from the viewpoint of market availability.

Specific examples of the cross-linking agent include polypropylene glycol diglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, and neopentyl. Polyglycidyl ethers such as glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, diethylene glycol diglycidyl ether, hydrogenated bisphenol A type diglycidyl ether. And so on. Among these, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diethanol are preferable. One or more selected from glycidyl ether and diethylene glycol diglycidyl ether, more preferably trimethylolpropane polyglycidyl ether.

The degree of cross-linking of the cross-linked polymer (a') is preferably 20 mol% or more, more preferably from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and improving the fixability. It is preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 45 mol% or more, and preferably 80 mol% or less, more preferably 70 mol% or less, still more preferably 60 mol% or less. , More preferably 55 mol% or less.
As described above, the degree of cross-linking of the cross-linked polymer (a') is the case where the polymer (a) is cross-linked with a cross-linking agent, and when the polymer (a) contains an acid group, the acid group of the polymer (a). It is the degree of cross-linking calculated from the equivalent of the cross-linking agent and the equivalent of the cross-linking functional group of the cross-linking agent, and is represented by "the number of molar equivalents of the cross-linking functional groups of the cross-linking agent / the number of molar equivalents of the acid groups of the polymer (a)". Will be done.
As described above, when a part of the acid group of the polymer (a) is neutralized, the neutralized acid group can also be a cross-linking point, so that the total of the degree of neutralization and the degree of cross-linking is 100 mol. If it exceeds%, the degree of cross-linking is represented by "molar equivalent number of cross-linking functional groups of the cross-linking agent / molar equivalent number of acid groups of the polymer (a)" as described above, and neutralization of the polymer (a'). The degree is a value obtained by subtracting the degree of cross-linking from 100 mol%.

The acid value of the crosslinked polymer (a') is preferably 40 mgKOH / g or more, more preferably 60 mgKOH / g or more, from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase and improving the storage stability. It is more preferably 80 mgKOH / g or more, still more preferably 100 mgKOH / g or more, still more preferably 110 mgKOH / g or more, and preferably 200 mgKOH / g or less, more preferably 180 mgKOH / g or less, still more preferably 160 mgKOH / g. It is g or less, more preferably 140 mgKOH / g or less, still more preferably 130 mgKOH / g or less. When the acid value is in the above range, the amount of the acid group can be sufficient to ensure the dispersion stability of the pigment. It is also preferable from the viewpoint of the balance between the affinity between the crosslinked polymer (a') and water and the interaction between the crosslinked polymer (a') and the pigment.
The acid value of the crosslinked polymer (a') can be measured by the method described in Examples.
The acid value of the crosslinked polymer (a') can also be determined by the following formula.
Acid value of crosslinked polymer (a') (mgKOH / g) = [Acid value of polymer (a) (mgKOH / g)] x [100-Crosslink degree (mol%)] / 100
Here, the acid value of the polymer (a) is as described above. Further, as described above, the degree of cross-linking is represented by "the number of molar equivalents of the cross-linking functional groups of the cross-linking agent / the number of molar equivalents of the acid groups of the polymer (a)".

At least a part of the acid group of the crosslinked polymer (a') is neutralized from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and the fixing property. Is preferable. Examples of the neutralizing agent used for neutralizing the crosslinked polymer (a') include the same as those exemplified above.
The counter ion of the neutralized acid group of the crosslinked polymer (a') is preferably an alkali metal cation, more preferably sodium ion (from the viewpoint of improving the dispersion stability of the pigment and improving the storage stability). One or more selected from Na ⁺ ) and potassium ion (K ⁺ ).
The degree of neutralization of the crosslinked polymer (a') may be such that a part of the acid groups of the crosslinked polymer (a') is neutralized or all of the acid groups are neutralized.

The present form of the polymer (a) or the crosslinked polymer (a') as the polymer dispersant A in the aqueous phase of the emulsion ink of the present invention includes a state of being adsorbed on the pigment and a state of containing the pigment ( There are a particle form in which the pigment is encapsulated (encapsulated), a particle form in which the pigment is uniformly dispersed), and a form in which the pigment is not adsorbed. From the viewpoint of improving the dispersion stability of the pigment and improving the storage stability, in the present invention, the pigment is contained in the polymer (a) particles (hereinafter, also referred to as “pigment-containing polymer particles”) or the pigment is crosslinked. The form of the particles contained in (a') (hereinafter, also referred to as "pigment-containing crosslinked polymer particles") is preferable, the form of the pigment-containing crosslinked polymer particles is more preferable, and the pigment is contained in the crosslinked polymer (a'). The morphology of the particles is even more preferred.

(Polymer particles B containing no pigment)
The aqueous phase contains the pigment-free polymer particles B (hereinafter, also referred to as “polymer particles B”) from the viewpoint of improving storage stability and fixability.
In the present invention, the polymer constituting the polymer particles B may have the same composition or different composition from the above-mentioned polymer dispersant A. When the polymer constituting the polymer particles B and the polymer dispersion A have the same composition, the presence form of the polymer (a) or the crosslinked polymer (a') as the polymer dispersant A is the pigment-containing polymer particles or In the case of the pigment-containing crosslinked polymer particles, the pigment-free polymer particles B and the pigment-containing polymer particles or the pigment-containing crosslinked polymer particles have the same composition, but differ only in the presence or absence of the pigment. Is preferable.

The polymer constituting the polymer particles B containing no pigment preferably contains an acid group from the viewpoint of improving storage stability and fixability. Examples of such an acid group include the same as those exemplified for the above-mentioned polymer dispersant A. Among them, a carboxy group (-COMM) is preferable from the viewpoint of improving storage stability and fixability.

At least a part of the acid group of the polymer particle B containing no pigment is medium from the viewpoint of improving the dispersion stability of the polymer particle B in the aqueous phase, improving the storage stability, and improving the fixability. It is preferable to be summed.
Examples of the neutralizing agent used for neutralization include alkali metal hydroxides and ammonia. Among them, alkali metal hydroxide is preferable, and hydroxide is more preferable, from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase, improving the storage stability, and improving the fixability. One or more selected from sodium and potassium hydroxide.
From the same viewpoint as described above, the degree of neutralization is preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 40 mol% or more, still more preferably 45 mol% or more, and preferably. It is 80 mol% or less, more preferably 70 mol% or less, still more preferably 60 mol% or less.
Specifically, the degree of neutralization (mol%) can be obtained by the following equation.
Degree of neutralization (mol%) = [{mass of neutralizer added (g) / equivalent of neutralizer} / [{acid value of polymer constituting polymer particles B (mgKOH / g) x mass of polymer particles B (G)} / (56.1 x 1,000)]] x 100

[Polymer (b)]
The pigment-free polymer particles B according to the present invention are not particularly limited as long as they have at least a fixing aid ability, but improve the dispersion stability of the polymer particles B in the aqueous phase and store stability. It may be composed of the non-crosslinked polymer (b) from the viewpoint of improving the fixability and the fixability. The polymer (b) preferably contains an acid group from the same viewpoint as described above.

Examples of the polymer (b) include polyester resins, polyurethane resins, vinyl resins and the like. Among them, a vinyl-based resin is preferable, and a vinyl-based resin containing a structural unit derived from a carboxy group-containing monomer and a structural unit derived from a hydrophobic monomer is more preferable. The vinyl-based resin may further contain a structural unit derived from a nonionic monomer.
Examples of the carboxy group-containing monomer, the hydrophobic monomer, and the nonionic monomer include the same as those exemplified for the above-mentioned polymer (a), and the preferred embodiment of each monomer and the preferable content of each monomer are also the same. ..

That is, the polymer (b) according to the present invention preferably contains a structural unit derived from one or more carboxy group-containing monomers selected from acrylic acid and methacrylic acid, an aromatic group-containing monomer, and a hydrocarbon derived from an aliphatic alcohol. A vinyl-based resin containing a (meth) acrylate having a group and a structural unit derived from one or more hydrophobic monomers selected from aromatic group-containing monomer-based macromonomers, and further containing a structural unit derived from a nonionic monomer. Although it may be a vinyl-based resin, it is more preferable to use an acrylic acid and the like from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase, improving the storage stability, and improving the fixability. Derived from one or more hydrophobic monomers selected from constituent units derived from one or more carboxy group-containing monomers selected from methacrylic acid and (meth) acrylates having hydrocarbon groups derived from aromatic group-containing monomers and aliphatic alcohols. It is a vinyl-based resin containing the constituent units of, and more preferably, a constituent unit derived from one or more carboxy group-containing monomers selected from acrylic acid and methacrylic acid, and a styrene-based monomer and an aromatic group-containing (meth) acrylate. A vinyl-based resin containing a structural unit derived from one or more hydrophobic monomers selected from the above.

The acid value of the polymer (b) is preferably 60 mgKOH / g or more from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase to improve the storage stability and the fixability. It is more preferably 100 mgKOH / g or more, still more preferably 140 mgKOH / g or more, still more preferably 180 mgKOH / g or more, still more preferably 220 mgKOH / g or more, and preferably 320 mgKOH / g or less, more preferably 300 mgKOH / g. It is g or less, more preferably 280 mgKOH / g or less, still more preferably 260 mgKOH / g or less. When the acid value is in the above range, the amount of acid groups sufficient to secure the dispersion stability of the polymer particles B can be set.
The acid value of the polymer particles B containing no pigment can be measured by the method described in Examples. In addition, it can be calculated from the mass ratio of the constituent monomers.

[Crosslinked polymer (b')]
It is preferable that the polymer constituting the pigment-free polymer particles B according to the present invention contains a crosslinked structure. That is, the pigment-free polymer particles B are preferably crosslinked polymer particles B that are composed of a crosslinked polymer and do not contain a pigment.
The polymer constituting the crosslinked polymer particles B containing no pigment is preferably crosslinked from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase to improve the storage stability and the fixing property. A polymer having a crosslinked structure crosslinked with an agent or a polymer having a self-crosslinking structure having a crosslinkable group introduced therein, more preferably a polymer having a crosslinked structure crosslinked with a crosslinking agent, and still more preferably the above-mentioned polymer. It is a crosslinked polymer (b') in which a non-crosslinked polymer (b) is crosslinked with a crosslinking agent.
That is, the crosslinked polymer (b') has a structure derived from a crosslinking agent in addition to the structural unit derived from the monomer constituting the polymer (b). Since the crosslinked polymer (b') has a crosslinked structure, aggregation of the polymer particles B in the aqueous phase, particularly depletion aggregation, is suppressed, the dispersion stability of the polymer particles B in the aqueous phase is improved, and the polymer is further prepared. It is considered that the storage stability can be improved because the swelling of the emulsion ink can be suppressed and the entire system of the emulsion ink can be stabilized.
Examples of the cross-linking agent include the same as those exemplified for the above-mentioned polymer dispersant A, and preferred embodiments of the cross-linking agent are also the same.

The degree of cross-linking of the cross-linked polymer (b') is preferably 20 mol% from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase to improve the storage stability and the fixability. The above is more preferably 30 mol% or more, further preferably 40 mol% or more, still more preferably 45 mol% or more, and preferably 80 mol% or less, more preferably 70 mol% or less, still more preferably 60. It is mol% or less, more preferably 55 mol% or less.
As described above, the degree of cross-linking of the cross-linked polymer (b') is the case where the polymer (b) is cross-linked with a cross-linking agent, and when the polymer (b) contains an acid group, the acid group of the polymer (b). It is the degree of cross-linking calculated from the equivalent of the cross-linking agent and the equivalent of the cross-linking functional group of the cross-linking agent, and is represented by "the number of molar equivalents of the cross-linking functional groups of the cross-linking agent / the number of molar equivalents of the acid groups of the polymer (b)". Will be done.
As described above, when a part of the acid group of the polymer (b) is neutralized, the neutralized acid group can also be a cross-linking point, so that the total of the degree of neutralization and the degree of cross-linking is 100 mol. If it exceeds%, the degree of cross-linking is expressed as "molar equivalent number of cross-linking functional groups of the cross-linking agent / molar equivalent number of acid groups of the polymer (b)" as described above, and neutralization of the polymer (b'). The degree is a value obtained by subtracting the degree of cross-linking from 100 mol%.

The acid value of the crosslinked polymer (b') is preferably 40 mgKOH / g from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase to improve the storage stability and the fixability. The above is more preferably 60 mgKOH / g or more, further preferably 80 mgKOH / g or more, still more preferably 100 mgKOH / g or more, still more preferably 110 mgKOH / g or more, and preferably 200 mgKOH / g or less, more preferably 200 mgKOH / g or more. It is 180 mgKOH / g or less, more preferably 160 mgKOH / g or less, still more preferably 140 mgKOH / g or less, still more preferably 130 mgKOH / g or less. When the acid value is in the above range, the amount of acid groups sufficient to ensure the dispersion stability of the polymer particles (B) can be set.
The acid value of the crosslinked polymer (b') can be measured by the method described in Examples.
When the cross-linked polymer (b') is obtained by cross-linking the polymer (b) with a cross-linking agent, the acid value of the cross-linked polymer (b') can also be obtained by the following formula.
Acid value of crosslinked polymer (b') (mgKOH / g) = [Acid value of polymer (b) (mgKOH / g)] x [100-Crosslink degree (mol%)] / 100
Here, the acid value of the polymer (b) can be calculated from the mass ratio of the constituent monomers. Further, as described above, the degree of cross-linking is represented by "the number of molar equivalents of the cross-linking functional groups of the cross-linking agent / the number of molar equivalents of the acid groups of the polymer (b)".

At least a part of the acid group of the crosslinked polymer (b') is neutralized from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase to improve the storage stability and the fixing property. It is preferable to be. Examples of the neutralizing agent used for neutralizing the crosslinked polymer (b') include the same as those exemplified for the above-mentioned polymer (a).
The counter ion of the neutralized acid group of the crosslinked polymer (b') is preferably an alkali metal cation from the viewpoint of improving the dispersion stability of the polymer particles B in the aqueous phase and improving the storage stability. , More preferably one or more selected from sodium ion (Na ⁺ ) and potassium ion (K ⁺ ).
The degree of neutralization of the crosslinked polymer (b') may be such that a part of the acid groups of the crosslinked polymer (b') is neutralized or all of the acid groups are neutralized.

(Surfactant)
In the emulsion ink of the present invention, a surfactant may be contained in the aqueous phase. Surfactants can improve the dispersion stability of pigments in the aqueous phase, reduce the energy at the interface between the aqueous phase and the oil phase, contribute to the formation of a stable dispersed phase, and improve storage stability. It is thought that it can be done. From this point of view, the surfactant is preferably a nonionic surfactant, more preferably an acetylene glycol-based surfactant, a polyoxyalkylene alkyl ether type surfactant, a polyether-modified silicone-based surfactant, and a polyether-modified silicone-based surfactant. One or more selected from fluorine-based surfactants, more preferably one selected from acetylene glycol-based surfactants and polyether-modified silicone-based surfactants, and even more preferably acetylene glycol-based surfactants. Is.
The HLB (hydrophilic lipophilic balance) value of the nonionic surfactant is preferably 6 or more, more preferably 8 or more, still more preferably 10 or more, still more preferably 12 or more, and preferably 20 or less. More preferably, it is 18 or less.
The HLB value is a value indicating the affinity of the surfactant for water and oil, and can be obtained from the following formula by the Griffin method. In the following formula, examples of the "hydrophilic group contained in the surfactant" include a hydroxyl group and an ethyleneoxy group.
HLB = 20 × [(sum of formulas of hydrophilic groups contained in surfactant) / (molecular weight of surfactant)]

The acetylene glycol-based surfactant is preferably an adduct of 2,4,7,9-tetramethyl-5-decine-4,7-diol, an adduct of ethylene oxide (hereinafter, also referred to as “EO”), 3,6-dimethyl-. EO adduct of 4-octin-3,6-diol, EO adduct of 2,5-dimethyl-3-hexin-2,5-diol, 2,5,8,11-tetramethyl-6-dodecine-5 , 8-diol EO adduct, and 3,5-dimethyl-1-hexin-3-ol EO adduct, more preferably 2,4,7,9-tetramethyl-. EO adduct of 5-decine-4,7-diol, EO adduct of 3,6-dimethyl-4-octin-3,6-diol, and 2,5-dimethyl-3-hexine-2,5-diol It is one or more selected from the EO adducts of the above, and more preferably 2,4,7,9-tetramethyl-5-decine-4,7-diol EO adducts.
The average number of moles of EO of the above-mentioned EO adduct used as an acetylene glycol-based surfactant is preferably 5 or more, more preferably 6 or more, still more preferably 7 or more, still more preferably 8 or more, and It is preferably 40 or less, more preferably 36 or less, still more preferably 32 or less.
Examples of commercially available acetylene glycol-based surfactants include the surfinol series manufactured by Nisshin Chemical Industry Co., Ltd .; the acetylenol series manufactured by Kawaken Fine Chemical Co., Ltd. and the like.

The polyether-modified silicone-based surfactant preferably has a structure in which the hydrocarbon group at the side chain and / or the terminal of the silicone oil is replaced with a polyether group. As the polyether group, a polyethylene oxy group, a polypropylene oxy group, an ethylene oxy group (EO) and a propylene oxy group (trymethylene oxy group or propane-1,2-diyl oxy group; PO) were added in a block shape or at random. A polyalkyleneoxy group is preferable, and a compound in which a polyether group is grafted on a silicone main chain, a compound in which a silicone and a polyether group are bonded in a block shape, and the like can be used.
Commercially available products of polyether-modified silicone-based surfactants include KF-353, KF-355A, KF-642 manufactured by Shinetsu Chemical Industry Co., Ltd .; Silface SAG005 manufactured by Nisshin Chemical Industry Co., Ltd .; NUC Co., Ltd. FZ-2191 and the like; BYK-348 and the like manufactured by Big Chemie Japan Co., Ltd. can be mentioned.

(Water-soluble organic solvent)
In the emulsion ink of the present invention, the aqueous phase further contains a water-soluble organic solvent from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and the fixability. You may.
The water-soluble organic solvent refers to an organic solvent having a dissolution amount of 10 mL or more when the organic solvent is dissolved in 100 mL of water at 25 ° C.
The water-soluble organic solvent is preferably one that is usually used in the aqueous phase of a water-in-oil emulsion ink and can be mixed with water in an arbitrary ratio, and is preferably an alkanol having 1 or more and 4 or less carbon atoms, a polyhydric alcohol, and a polyhydric alcohol alkyl. Examples thereof include ethers, ketones, cyclic ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds. Among these, one or more selected from polyhydric alcohols and polyhydric alcohol alkyl ethers are more preferable.
The boiling point of the water-soluble organic solvent is preferably 60 ° C. or higher, more preferably 90 ° C. or higher, still more preferably 150 ° C. or higher, and preferably 350 ° C. or lower, more preferably 330 ° C. or lower, still more preferably 310 ° C. It is as follows.
As the water-soluble organic solvent, one kind may be used alone or two or more kinds may be used in combination as long as it can be miscible with water at an arbitrary ratio.

In the present invention, the aqueous phase may contain a viscosity modifier, an antifoaming agent, a preservative, an antifungal agent, an anticorrosive agent and the like as long as the effects of the present invention are not impaired.
<Oil phase>
The oil phase of the emulsion ink of the present invention contains a water-insoluble organic solvent and an emulsifier from the viewpoint of improving storage stability and fixability.

(Water-insoluble organic solvent)
The water-insoluble organic solvent refers to an organic solvent whose dissolution amount is less than 10 mL when the organic solvent is dissolved in 100 mL of water at 25 ° C.
As the water-insoluble organic solvent, either a non-polar organic solvent or a polar organic solvent can be used. These may be used alone or in combination of two or more as long as they form a single continuous phase.

Examples of the non-polar organic solvent include aliphatic hydrocarbon solvents such as paraffin-based, isoparaffin-based and naphthen-based solvents, alicyclic hydrocarbon solvents and hydrocarbon solvents such as aromatic hydrocarbon solvents.
The initial distillate of the non-polar organic solvent is preferably 90 ° C. or higher, more preferably 150 ° C. or higher, and preferably 300 ° C. or lower, more preferably 250 ° C. or lower.
Commercially available non-polar organic solvents include Isopar (trade name) series, Exor (trade name) series (both manufactured by ExxonMobil); AF solvent (trade name) series (manufactured by JXTG Energy Co., Ltd.), etc. Be done.

Examples of the polar organic solvent include ester-based solvents and higher alcohol-based solvents.
As the ester solvent, a fatty acid ester solvent is preferable. Examples of the fatty acid ester-based solvent include isononyl isononanoate, isodecyl isononanoate, isotridecyl isononanoate, methyl laurate, isopropyl laurate, hexyl laurate, 2-ethylhexyl laurate, isopropyl myristate, isopropyl palmitate, and isostearyl palmitate. Methyl oleate, ethyl oleate, isopropyl oleate, isobutyl oleate, methyl linoleate, ethyl linoleate, isobutyl linoleate, butyl stearate, 2-ethylhexyl stearate, isopropyl isostearate, methyl soybean oil, isobutyl soybean oil, Methyl tall oil, isobutyl tall oil, propylene glycol monocaprate, diisopropyl adipate, diisopropyl sebacate, diethyl sebacate, trimethyl propane tri-2-ethylhexanoate, glyceryl tri2-ethylhexanoate, etc. have 13 or more carbon atoms and 30 The following fatty acid esters are mentioned.
Examples of the higher alcohol solvent include higher alcohols having 12 or more and 20 or less carbon atoms such as isomiristyl alcohol, isopalmityl alcohol, isostearyl alcohol, and oleyl alcohol.

The water-insoluble organic solvent preferably contains one or more selected from a hydrocarbon solvent and an ester solvent from the viewpoint of improving storage stability and fixability, and more preferably a hydrocarbon solvent and an ester solvent. include.
When the water-insoluble organic solvent contains a hydrocarbon solvent and an ester solvent, the content of the hydrocarbon solvent in the water-insoluble organic solvent is preferably 50% by mass from the viewpoint of improving storage stability and fixability. % Or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and preferably 90% by mass or less, still more preferably 80% by mass or less.

(emulsifier)
The emulsifier is not particularly limited as long as it is contained in the oil phase and can emulsify the aqueous phase to form a water-in-oil emulsion, but lipophilic emulsifiers such as surfactants and polymer dispersants are preferable.
As the lipophilic surfactant, a nonionic surfactant having an HLB value of 6 or less is preferable. Examples of the nonionic surfactant include sorbitan fatty acid esters such as sorbitan monooleate, sorbitan sesquioleate, and sorbitan monostearate; and polyoxyethylene sorbitan fatty acids such as polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate. Esters; Glycerin fatty acid esters such as glycerol monostearate and glycerol monooleate; Polyoxyethylene glycerin fatty acid esters such as polyoxyethylene sorbit fatty acid esters and polyoxyethylene glycerin vegetable oil fatty acid esters; Sucrose fatty acid esters such as esters, sucrose oleic acid esters, sucrose erucic acid esters, and sucrose lauric acid esters; polyethylene glycol fatty acid esters; polyglycerin condensed lysinoleic acid esters; polyoxyethylene alkyl ethers; polyoxyethylene alkyl phenyl ethers. ; Polyoxyethylene alkylamine / fatty acid amide; polyoxyethylene polyoxypropylene alkyl ether and the like.
The lipophilic surfactant may be used alone or in combination of two or more.

Examples of oil-based polymer dispersants include polyester polyimine, polyester polyamine, polyalkylolaminoamide and its salt, polyether polyamine, hydroxyl group-containing carboxylic acid ester, long-chain polyamino amide and high molecular weight acid ester salt, and high molecular weight poly. Carbonic acid salt, long-chain polyaminoamide and polar acid ester salt, high molecular weight unsaturated acid ester, modified polyurethane, modified poly (meth) acrylate, polyether ester type anionic activator, naphthalene sulfonic acid formarin condensate salt, Examples thereof include polyoxyethylene alkyl phosphate, polyoxyethylene nonylphenyl ether, and stearylamine acetate. Among these, one or more selected from polyester polyimine, polyester polyamine, polyalkylolaminoamide and its salt, and polyether polyamine are preferable, and polyester polyimine is more preferable. These may be used individually by 1 type or in combination of 2 or more type.

The polyester polyimine preferably consists of an amide or salt formed by reacting a polyalkyleneimine such as polyethyleneimine with a polyester having a carboxy group such as a polymer of hydroxystearic acid or a polymer of a cyclic ester. A dispersant having a graft structure in which two or more polyester chains are bonded to a polyalkyleneimine chain as a trunk can be mentioned. When the water-insoluble organic solvent contains an ester solvent, the interaction between the dispersed phase droplet particles is suppressed by the steric repulsive force in the oil phase of the polyester chain of the polyester polyimine, and the dispersed phase droplet particles It is considered that the suppression of coalescence stabilizes the entire emulsion ink system and improves storage stability.
Commercially available oil-based polymer dispersants include, for example, Solspers (trade name) series manufactured by Japan Lubrizol Co., Ltd .; Efka (trade name) series manufactured by Efka CHEMICALS; Disparon (trade name) manufactured by Kusumoto Kasei Co., Ltd. ) Series; Ajispar (trade name) series manufactured by Ajinomoto Co., Ltd. can be mentioned.

In the present invention, the oil phase preferably does not contain a colorant such as a pigment from the viewpoint of improving storage stability and fixability.

[Manufacturing method of water-in-oil emulsion ink]
The water-in-oil emulsion ink of the present invention is a method including the following step I from the viewpoint of improving the dispersion stability of the pigment in the aqueous phase to improve the storage stability and the fixability. It is preferable to obtain by.
Step I: Contains an aqueous phase component containing an aqueous pigment dispersion in which the pigment is dispersed in an aqueous medium with a polymer dispersant A, an aqueous dispersion of polymer particles B containing no pigment, and a water-insoluble organic solvent and an emulsifier. Step of mixing and emulsifying oil phase components to obtain water-in-oil emulsion ink Here, the "water-based" in the water-based pigment dispersion means that water occupies the largest proportion in the medium in which the pigment is dispersed. Means. Further, the "water-based" in the aqueous dispersion of the polymer particles B containing no pigment means that water occupies the maximum proportion in the medium in which the polymer particles B containing no pigment are dispersed.

When the aqueous phase contains the above-mentioned surfactant, water-soluble organic solvent, or optional component, an aqueous pigment dispersion, an aqueous dispersion of polymer particles B containing no pigment, and a surfactant if necessary. , A water-soluble organic solvent, or an optional component is mixed, or the water content is adjusted to prepare an aqueous phase component, and then the aqueous phase component and the oil phase component are mixed and emulsified to form an aqueous phase. Can obtain a water-in-oil emulsion ink dispersed in the oil phase.
The blending amount of the aqueous phase component is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, from the viewpoint of productivity and obtaining a stable emulsion with respect to 100 parts by mass of the oil phase component. It is more preferably 30 parts by mass or more, preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and more preferably 40 parts by mass or less.

The stirring means used for mixing and emulsification in step I is not particularly limited as long as it can give a shearing force, but a homogenizer (for example, "Ultra Tarax" of IKA Japan Co., Ltd.), a homomixer, etc. A high-speed stirring / mixing device such as a disper (for example, "Ultra Disper" of Asada Iron Works Co., Ltd.) is preferable.
For example, when a homogenizer is used, when the aqueous phase component is dropped onto the oil phase component, the rotation speed of the homogenizer is preferably 500 rpm or more, more preferably 1,000 rpm or more, still more preferably 1,500 rpm or more. The adjustment is preferably 8,000 rpm or less, more preferably 7,000 rpm or less, still more preferably 6,000 rpm or less. Then, after the addition of the aqueous phase component is completed, the rotation speed of the homogenizer is preferably 5,000 rpm or more, more preferably 7,000 rpm or more, further preferably 10,000 rpm or more, and preferably 20,000 rpm or less. , More preferably 17,000 rpm or less, still more preferably 15,000 rpm or less.

[Manufacturing of water-based pigment dispersion]
In the present invention, when the pigment is dispersed as the polymer dispersant A by the non-crosslinked polymer (a), it is preferable to efficiently produce the aqueous pigment dispersion by the method including the following step A1.
Step A1: A step of dispersing a pigment mixture containing a pigment, a polymer (a) and water to obtain an aqueous pigment dispersion in which the pigment is dispersed in an aqueous medium with the polymer (a).

(Step A1)
In step A1, specifically, (1) a method for dispersing and treating a pigment mixture obtained by mixing an aqueous dispersion of particles (a) particles and a pigment; (2) a pigment, a polymer (a), and the like. A pigment mixture containing an organic solvent, water, and if necessary, a neutralizing agent, a surfactant, etc. may be dispersed to obtain a dispersion liquid, and then the organic solvent may be removed from the dispersion liquid. preferable. Above all, the method (1) is preferable from the viewpoint of improving storage stability and fixability.

In the case of the method (1), it is preferable to have the following step A1-1 before the step A1.
Step A1-1: Part of the acid group of the polymer (a) is neutralized with a neutralizing agent to obtain an aqueous dispersion of the polymer (a) particles. Step A Preferred neutralizing agent used for neutralization in the step A1-1. And the degree of neutralization of the polymer (a) is as described above. The neutralizing agent is preferably used as an aqueous solution from the viewpoint of sufficiently and uniformly promoting neutralization.

In the dispersion treatment in step A1, the pigment can be atomized to a desired particle size only by the main dispersion due to shear stress, but from the viewpoint of obtaining a uniform aqueous pigment dispersion, after the pigment mixture is pre-dispersed, the pigment mixture is pre-dispersed. Further, it is preferable to carry out this dispersion.
As the disperser used for the pre-dispersion, a commonly used mixing / stirring device such as an anchor blade and a disper blade can be used.
Examples of the means for applying the shear stress used for this dispersion include a kneader such as a roll mill and a kneader, a high-pressure homogenizer such as a microfluidizer, a paint shaker, and a media type disperser such as a bead mill. Among these, it is preferable to use a high-pressure homogenizer from the viewpoint of reducing the particle size of the pigment.
When the dispersion treatment is performed using a high-pressure homogenizer, the pigment can be controlled to have a desired particle size by controlling the treatment pressure and the number of passes, and the cumulant average particle size of the aqueous pigment dispersion described later is also adjusted. be able to.
The processing pressure is preferably 60 MPa or more and 300 MPa or less from the viewpoint of productivity and economy.
The number of passes is preferably 3 or more, more preferably 7 or more from the viewpoint of reducing the particle size of the pigment, and preferably 30 or less, more preferably 20 or less from the viewpoint of dispersion stability of the pigment. ..
When the pigment mixture contains an organic solvent, an aqueous pigment dispersion can be obtained by removing the organic solvent by a known method. It is preferable that the organic solvent in the obtained aqueous pigment dispersion is substantially removed, but it may remain as long as the object of the present invention is not impaired. The amount of the residual organic solvent is preferably 0.1% by mass or less, more preferably 0.01% by mass or less.

(Step A2)
In the present invention, when the pigment is dispersed as the polymer dispersant A by the crosslinked polymer (a'), the aqueous pigment dispersion is further added after step A1, preferably after steps A1-1 and A1. It is preferably obtained by a method including the following step A2.
Step A2: A water-based pigment dispersion obtained by adding a cross-linking agent to the water-based pigment dispersion obtained in step A1, cross-linking the polymer (a) with the cross-linking agent, and dispersing the pigment with the cross-linked polymer (a'). Process to obtain

In step A2, the preferable cross-linking agent and degree of cross-linking are as described above.
The temperature of the crosslinking treatment is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher, and preferably 95 ° C. or lower, more preferably 85 ° C. or lower, still more preferably 75 ° C. or lower. Is.
The time of the cross-linking treatment is preferably 0.5 hours or more, more preferably 1 hour or more, further preferably 3 hours or more, and preferably 12 hours or less, from the viewpoint of completion of the cross-linking reaction and economic efficiency. It is preferably 10 hours or less, more preferably 8 hours or less.

The concentration of the non-volatile component (solid content concentration) of the aqueous pigment dispersion is preferably 20% by mass or more from the viewpoint of improving the dispersion stability to improve the storage stability and facilitating the production of ink. It is preferably 30% by mass or more, more preferably 40% by mass or more, and preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less. The solid content concentration of the aqueous pigment dispersion is measured by the method described in Examples.

The average cumulant particle size of the aqueous pigment dispersion is preferably 50 nm or more, more preferably 60 nm or more, still more preferably 70 nm or more, still more preferably 80 nm or more, still more preferably, from the viewpoint of improving storage stability and fixability. Is 90 nm or more, and is preferably 200 nm or less, more preferably 150 nm or less, still more preferably 130 nm or less, still more preferably 100 nm or less, still more preferably less than 100 nm.
The cumulant average particle size of the aqueous pigment dispersion is measured by the method described in Examples.

The aqueous pigment dispersion is preferably one in which pigment-containing polymer particles are dispersed in an aqueous medium. The form of the pigment-containing polymer particles is not particularly limited, and the particles may be formed by at least the non-crosslinked polymer (a) or the crosslinked polymer (a') with the pigment, but as described above, the non-crosslinked polymer ( It is preferably in the form of particles in which the pigment is encapsulated in a) or the crosslinked polymer (a').
The aqueous pigment dispersion may contain 1% by mass or more and 10% by mass or less of glycerin, polyethylene glycol or the like as a moisturizer to prevent drying, or may contain an additive such as an antifungal agent.
The above additive may be added when the pigment is dispersed in the polymer (a), or may be added after the pigment is dispersed or crosslinked.

[Manufacturing an aqueous dispersion of polymer particles B containing no pigment]
As the polymer particles B (polymer particles B) containing no pigment, those synthesized as appropriate may be used, or commercially available products may be used, but it is preferable to use them as an aqueous dispersion.
The aqueous dispersion of the polymer particles B is obtained by obtaining a polymer constituting the polymer particles B by a known polymerization method, and then stirring the mixture containing the polymer, water and, if necessary, a neutralizing agent while heating. Then, the temperature is lowered; the mixture containing the polymer, the organic solvent, the neutralizing agent, and water is dispersed to obtain a dispersion liquid, and then the organic solvent is removed from the dispersion liquid. Can be done. Above all, from the viewpoint of workability, a method of stirring the mixture containing the polymer, water, and the neutralizing agent while heating the mixture and then lowering the temperature is preferable.

The temperature at which the mixture is stirred is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, still more preferably 80 ° C. or higher, and preferably 100 ° C. or lower, more preferably 95 ° C. or lower. The stirring time is preferably 0.5 hours or more, more preferably 1 hour or more, further preferably 3 hours or more, and preferably 30 hours or less, more preferably 15 hours or less, still more preferably 10 hours or less. be.

When the polymer constituting the polymer particles B is a non-crosslinked polymer (b), the aqueous dispersion of the polymer particles B is preferably neutralized with a neutralizing agent. In this case, it is preferable that the aqueous dispersion of the polymer particles B has the following step B1-1.
Step B1-1: Part of the acid group of the polymer (b) is neutralized with a neutralizing agent to obtain an aqueous dispersion of the polymer (b) particles. A preferred neutralizing agent used for neutralization in the step B1-1. And the degree of neutralization of the polymer (b) is as described above. The neutralizing agent is preferably used as an aqueous solution from the viewpoint of sufficiently and uniformly promoting neutralization.

(Step B1)
When the polymer particles B are composed of a crosslinked polymer (b') obtained by cross-linking the non-crosslinked polymer (b) with a cross-linking agent, the aqueous dispersion of the polymer particles B is further added after step B1-1. It is preferably obtained by a method including the following step B1.
Step B1: A cross-linking agent is added to the aqueous dispersion of the polymer (b) particles obtained in step B1-1, and the polymer (b) is cross-linked with the cross-linking agent to be composed of the cross-linked polymer (b'). Step of obtaining an aqueous dispersion of polymer particles B containing no pigment

In step B1, the preferable cross-linking agent and degree of cross-linking are as described above.
The temperature of the crosslinking treatment is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher, and preferably 95 ° C. or lower, more preferably 85 ° C. or lower, still more preferably 75 ° C. or lower. Is.
The time of the cross-linking treatment is preferably 0.5 hours or more, more preferably 1 hour or more, further preferably 3 hours or more, and preferably 12 hours or less, from the viewpoint of completion of the cross-linking reaction and economic efficiency. It is preferably 10 hours or less, more preferably 8 hours or less.

The concentration of the non-volatile component (solid content concentration) of the aqueous dispersion of the polymer particles B is from the viewpoint of improving the dispersion stability of the polymer particles B to improve the storage stability, the viewpoint of improving the fixability, and the production of ink. From the viewpoint of facilitation, it is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 35% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably. Is 45% by mass or less. The solid content concentration of the aqueous dispersion of the polymer particles B is measured by the method described in Examples.

The cumulant average particle size of the aqueous dispersion of the polymer particles B is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, and preferably 200 nm from the viewpoint of improving storage stability and fixability. Below, it is more preferably 150 nm or less, still more preferably 100 nm or less. The average particle size is measured by the method described in Examples.

The emulsion ink of the present invention further comprises, if necessary, a moisturizing agent, a wetting agent, a penetrant, a dispersant, a surfactant, a viscosity modifier, an antifoaming agent, a preservative, which are usually used for water-in-oil emulsion inks. Various additives such as antifungal agents and antiseptic agents can be added, and further filtration treatment with a filter or the like can be performed.
The content and physical properties of each component in the emulsion ink of the present invention are as follows.

The content of the pigment in the emulsion ink is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, still more preferably 5% by mass or more, from the viewpoint of improving the printing density. Yes, and from the viewpoint of lowering the ink viscosity at the time of volatilization of the solvent and improving the storage stability, it is preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 7% by mass or less.

The total content of the pigment and the polymer dispersant A in the emulsion ink is preferably 3% by mass or more, more preferably 4% by mass or more, still more preferably 5% by mass or more, and preferably 15% by mass or less. , More preferably 10% by mass or less, still more preferably 7% by mass or less.

The mass ratio of the pigment content to the content of the polymer dispersant A in the emulsion ink of the present invention [pigment / polymer dispersant A] is preferably 1 or more, more preferably 3 or more from the viewpoint of improving the printing density. It is more preferably 5 or more, still more preferably 6 or more, and preferably 10 or less, more preferably 9 or less, still more preferably, from the viewpoint of improving the dispersion stability of the pigment and improving the storage stability. Is 8 or less.
Here, when the polymer dispersant A is a non-crosslinked polymer (a), the mass ratio [pigment / polymer dispersant A] is the mass ratio of the pigment in the aqueous phase to the non-crosslinked polymer (a). When the polymer is a [pigment / non-crosslinked polymer (a)] and the polymer dispersant is a crosslinked polymer (a'), the mass ratio [pigment / polymer dispersant A] is the pigment in the aqueous phase and the crosslinked polymer. The mass ratio with (a') [pigment / crosslinked polymer (a')].

The mass ratio of the content of the polymer particles B containing no pigment to the content of the pigment in the emulsion ink of the present invention [polymer particles B without pigment / pigment] is preferably 0. 05 or more, more preferably 0.1 or more, still more preferably 0.2 or more, still more preferably 0.3 or more, still more preferably 0.5 or more, and a stable emulsion is obtained and stored. From the viewpoint of improving stability, it is preferably 1.5 or less, more preferably 1.3 or less, still more preferably 1 or less.

The content of water in the emulsion ink of the present invention is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 9% by mass or more, still more, from the viewpoint of improving storage stability and fixability. It is preferably 10% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less, still more preferably 18% by mass or less.

The content of the water-insoluble organic solvent in the emulsion ink is preferably 50% by mass or more, more preferably 60% by mass or more, from the viewpoint of improving storage stability and fixability and adjusting the viscosity of the emulsion ink. It is more preferably 65% by mass or more, still more preferably 70% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 75% by mass or less.

The content of the emulsifier in the emulsion ink is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more, from the viewpoint of stabilizing the emulsion and improving the storage stability. And, preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 7% by mass or less.

In the present invention, the pigment-containing polymer particles or the pigment-containing crosslinked polymer particles in the aqueous phase cause swelling, shrinkage, and aggregation between the particles from the viewpoint of improving the dispersion stability of the pigment and improving the storage stability. When the emulsion ink of the present invention is produced using the above-mentioned water-based pigment dispersion, the average particle size of the pigment-containing polymer particles or the pigment-containing crosslinked polymer particles is the same as that of the water-based pigment dispersion. It is preferably the same as the average particle size of the cumulant. That is, the average particle size of the pigment-containing polymer particles or the pigment-containing crosslinked polymer particles in the aqueous phase is preferably 50 nm or more, more preferably 60 nm or more, still more preferably 70 nm or more, still more preferably 80 nm or more, still more preferably. Is 90 nm or more, and is preferably 200 nm or less, more preferably 150 nm or less, still more preferably 130 nm or less, still more preferably 100 nm or less, still more preferably less than 100 nm.
When measuring the average particle size of the pigment-containing polymer particles or the pigment-containing crosslinked polymer particles in the aqueous phase from the emulsion ink, for example, the aqueous phase component is recovered from the emulsion ink to contain the pigment-containing polymer particles or the pigment. The average particle size of the crosslinked polymer particles can be measured by observing with an electronic microscope.

In the present invention, the pigment-free polymer particles B in the aqueous phase are preferably free from swelling, shrinkage, and aggregation between the particles from the viewpoint of improving storage stability and fixability, and the emulsion ink of the present invention. However, when produced using the above-mentioned aqueous dispersion of the polymer particles B containing no pigment, the average particle size of the polymer particles B containing no pigment is the same as that of the aqueous dispersion of the polymer particles B containing no pigment. It is preferably the same as the average particle size of the cumulant. That is, the average cumulant particle size of the pigment-free polymer particles B in the aqueous phase is preferably 1 nm or more, more preferably 5 nm or more, further preferably 10 nm or more, and preferably 200 nm or less, more preferably 150 nm. Below, it is more preferably 100 nm or less.
When measuring the average particle size of the pigment-free polymer particles B in the aqueous phase from the emulsion ink, for example, the aqueous phase component is recovered from the emulsion ink and the average particles of the polymer particles B containing no pigment are measured. The diameter can be measured by observing with an electronic microscope.

In the present invention, the average particle size of the emulsion is preferably 0.1 μm or more, more preferably 0.3 μm or more, still more preferably 0. It is 5 μm or more, preferably 2.0 μm or less, more preferably 1.7 μm or less, still more preferably 1.5 μm or less.
The average particle size of the emulsion is measured by the method described in Examples.

The viscosity of the emulsion ink of the present invention at 25 ° C. is preferably 2 mPa · s or more, more preferably 5 mPa · s or more, still more preferably 7 mPa · s or more, still more preferably 9 mPa · s or more, and the emulsion. From the viewpoint of using the ink for inkjet recording, it is preferably 20 mPa · s or less, more preferably 17 mPa · s or less, still more preferably 15 mPa · s or less, still more preferably 13 mPa · s or less.
The viscosity of the emulsion ink can be measured using an E-type viscometer (type: TV-25, manufactured by Toki Sangyo Co., Ltd., standard cone rotor 1 ° 34'x R24 used, rotation speed 50 rpm).

The emulsion ink of the present invention is preferably used for inkjet recording from the viewpoint of ejection property. The emulsion ink can be loaded into a known inkjet recording device and ejected as ink droplets onto a printing medium to record an image or the like.
Examples of the printing medium used include high water absorption plain paper, low water absorption coated paper, and non-water absorption resin film. Examples of the coated paper include general-purpose glossy paper and multicolor foam gloss paper. The resin film is preferably at least one selected from a polyester film, a polyvinyl chloride film, a polypropylene film, and a polyethylene film. As the resin film, a corona-treated base material may be used.
Among these, plain paper is preferable from the viewpoint of fixability.

In the following preparation examples, production examples, examples and comparative examples, "parts" and "%" are "parts by mass" and "% by mass" unless otherwise specified.
Various physical properties were measured by the following methods.

(1) Measurement of acid value JIS K0070, except that the measurement solvent was changed from a mixed solvent of ethanol and ether to a mixed solvent of ethanol and toluene [ethanol: toluene = 1: 1 (volume ratio)]. Measured according to K0070.

(2) Measurement of weight average molecular weight of vinyl-based resin Gel permeation using a solution prepared by dissolving phosphoric acid and lithium bromide in N, N-dimethylformamide at concentrations of 60 mmol / L and 50 mmol / L, respectively, as an eluent. Chromatography method [GPC device (model: HLC-8320GPC, manufactured by Toso Co., Ltd.), column (TSKgel SuperAWM-H, TSKgel SuperAW3000, TSKgel guardcolumn Super AW-H, above, trade name manufactured by Toso Co., Ltd.), flow velocity: 0 .5 mL / min], a monodisperse polystyrene kit [PStQuick B (F-550, F-80, F-10, F-1, A-1000), PStQuick C (F-288, F-1000), whose molecular weight is known as a standard substance. -40, F-4, A-5000, A-500), above, trade name manufactured by Toso Co., Ltd.] was used for the measurement.
For the measurement sample, 0.1 g of vinyl resin was mixed with 10 mL of the eluent in a glass vial, stirred at 25 ° C. for 10 hours with a magnetic stirrer, and a syringe filter (trade name: DISMIC-13HP, membrane filter material: A hydrophilic PTFE, a pore size of 0.2 μm, manufactured by Advantech Co., Ltd.) was used.

(3) Measurement of solid content concentration In a 30 mL polypropylene container (φ = 40 mm, height = 30 mm), 10.0 g of sodium sulfate homogenized in a desiccator was weighed, and about 1.0 g of a sample was added thereto. After mixing, the mixture was accurately weighed, maintained at 105 ° C. for 2 hours to remove volatile matter, and further left in a desiccator at room temperature (25 ° C.) for 15 minutes, and then the mass was measured. The mass of the sample after removing the volatile matter was taken as the solid content and divided by the mass of the added sample to obtain the solid content concentration.

(4) Measurement of average cumulant particle size Cumulant analysis was performed using a laser particle analysis system (model: ELS-8000, manufactured by Otsuka Electronics Co., Ltd.), and the average cumulant particle size was measured. The measurement conditions were a temperature of 25 ° C., an angle of 90 ° between the incident light and the detector, and 100 times of integration, and the refractive index of water (1.333) was input as the refractive index of the dispersion medium. The concentration of the measurement sample was 5 × 10 ^-3 % (in terms of solid content concentration).

(5) Average particle size of the emulsion The medium volume particle size (D ₅₀ ) measured using the laser diffraction / scattering type particle size measuring device "Mastersizer 3000" (manufactured by Malvern Panasonic) is the average of the emulsion. The particle size was used. The measurement sample was prepared by adding hexyl laurate (trade name: Exepearl HL, manufactured by Kao Corporation, viscosity at 20 ° C., 6.8 mPa · s) to emulsion ink and adjusting the concentration to a scattering intensity of 5 to 15%. Using. The measurement was carried out under the conditions of a particle refractive index of 1.59 (absorption rate of 0.1, density of 1 g / cm ³ ) and a dispersion medium refractive index of 1.44.

<Preparation of vinyl resin>
Preparation Example 1
Acrylic acid (19.2 parts), styrene (70.8 parts) and α-methylstyrene (10.0 parts) were mixed to prepare a raw material monomer. In the reaction vessel, 10 parts of methyl ethyl ketone (hereinafter referred to as "MEK"), 0.3 part of 2-mercaptoethanol (polymerization chain transfer agent), and 10% of the raw material monomer are put and mixed, and nitrogen gas substitution is sufficient. Went to.
On the other hand, the residue of the raw material monomer (90%), 0.27 part of the polymerization chain transfer agent, 40 parts of MEK and the azo radical polymerization initiator (trade name: V-65, Fujifilm Wako Pure Chemical Industries, Ltd.) are added to the dropping funnel. , 2,2'-azobis (2,4-dimethylvaleronitrile)) (hereinafter referred to as "V-65") 1.1 parts of the mixed solution is put in, and the raw material monomer in the reaction vessel is put in a nitrogen atmosphere. The temperature was raised to 65 ° C. with stirring, and the mixed solution in the dropping funnel was added dropwise over 3 hours. After stirring for 2 hours from the end of dropping while maintaining the contents in the reaction vessel at 65 ° C., a solution prepared by dissolving 0.15 part of the polymerization initiator in 2.5 parts of MEK was added, and the mixture was further added at 65 ° C. for 2 hours and 70. The mixture was aged at ° C. for 2 hours to obtain a solution of a vinyl resin (P1) having a carboxy group. Table 1 shows the weight average molecular weight and the acid value.

Preparation Example 2 and Preparation Example 4
In Preparation Example 1, solutions of vinyl resins (P2) and (P4) having a carboxy group were obtained in the same manner except that the composition of the raw material monomer was changed as shown in Table 1. Table 1 shows the weight average molecular weight and the acid value.

Preparation Example 3
37.0 parts of methacrylic acid, 33.0 parts of benzyl acrylate, styrene macromer (manufactured by Toa Synthetic Co., Ltd., trade name: AS-6S, number average molecular weight: 6,000, solid content concentration 50%) (hereinafter, "styrene macromer" 40.0 parts (20.0 parts as solid content), polypropylene glycol monomethacrylate (manufactured by Nichiyu Co., Ltd., trade name: Blemmer PP-800, average number of moles of propylene oxide added 13, terminal: hydroxyl group) 10.0 parts (hereinafter referred to as "PP-800") were mixed to prepare a raw material monomer. In the reaction vessel, 10 parts of MEK, 0.3 part of 2-mercaptoethanol (polymerization chain transfer agent), and 10% of the raw material monomer were put and mixed, and nitrogen gas replacement was sufficiently performed.
On the other hand, a mixed solution of the rest of the raw material monomer (90%), 0.27 parts of the polymerization chain transfer agent, 40 parts of MEK, and 1.1 parts of the azo radical polymerization initiator (V-65) is put into the dropping funnel. After that, a solution of a vinyl resin (P3) having a carboxy group was obtained in the same manner as in Preparation Example 1. Table 1 shows the weight average molecular weight and the acid value.

<Manufacturing of aqueous dispersion of polymer particles (step A1-1 and step B1-1)>
Production Example 1-1
The solution of the vinyl-based resin obtained in Preparation Example 1 was dried under reduced pressure, and then pulverized to obtain 80.0 parts of the vinyl-based resin (P1) with 316.0 parts of ion-exchanged water and a 5N sodium hydroxide aqueous solution 25. Add 3 parts so that the ratio of the number of moles of sodium hydroxide to the number of moles of the carboxy group of the vinyl resin (P1) is 50 mol% (neutralization degree: 50 mol%), and 90 while stirring at 150 rpm. It was neutralized and dispersed by heating at ° C. for 5 hours to obtain an aqueous dispersion (D1) of polymer particles (solid content concentration: 20%, cumulant average particle size: 56 nm).
Got

Production Examples 1-2 to 1-4
In Production Example 1-1, the aqueous dispersion (D2) of polymer particles is similarly modified except that the type of vinyl resin, the amount of sodium hydroxide aqueous solution, and the amount of ion-exchanged water are changed as shown in Table 2. -(D4) (both solid content concentration: 20% and neutralization degree: 50 mol%) were obtained.

<Manufacturing of water-based pigment dispersion (i) (step A1)>
Production Example 2-1
55.5 parts of the aqueous dispersion (D1) of the polymer particles obtained in Production Example 1-1, 400.0 parts of ion-exchanged water, cyan pigment (CI Pigment Blue 15: 3, DC Co., Ltd.) Manufactured by, trade name: TGR-SD) 100.0 parts are added, and using a disper (manufactured by Asada Iron Works Co., Ltd., trade name: Ultra Disper), the disperser blade is rotated at 7,000 rpm for 60 minutes at 20 ° C. Stirred. The obtained mixture was subjected to 10-pass dispersion treatment with a microfluidics (manufactured by Microfluidics, trade name) at a pressure of 200 MPa to obtain a dispersion-treated product.
The obtained dispersion-treated product was filtered with a needleless syringe (manufactured by Terumo Corporation) having a capacity of 25 mL and equipped with a 5 μm filter (acetyl cellulose membrane, outer diameter: 2.5 cm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). After removing the coarse particles, an aqueous pigment dispersion (i-1) having a solid content concentration of 20% was obtained.

Production Examples 2-2 to 2-4
In Production Example 2-1 the aqueous pigment dispersions (i-2) to (i-4) were obtained in the same manner except that the type of the aqueous dispersion of the polymer particles was changed as shown in Table 3.

<Manufacturing of water-based pigment dispersion (process A2)>
Production Example 3-1
100.0 parts (solid content concentration 20%) of the aqueous pigment dispersion (i-1) obtained in Production Example 2-1 was placed in a glass bottle with a screw cap, and a vinyl resin (P1) was used as the polymer (a). Trimethylolpropane polyglycidyl ether (trade name: Denacol EX-321, manufactured by Nagase ChemteX Corporation, epoxy equivalent: 139, water content: 27%) (hereinafter referred to as “EX-321”) 0.35 part was added and sealed, and the mixture was heated at 70 ° C. for 5 hours while stirring with a stirrer. After 5 hours, the temperature was lowered to room temperature, and a needleless syringe (manufactured by Terumo Co., Ltd.) with a capacity of 25 mL equipped with a 5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used. It is filtered and further concentrated under reduced pressure so that the content of the pigment in the obtained aqueous pigment dispersion is 40.0% by mass, and the aqueous cyan pigment dispersion (hereinafter, also referred to as “cyan pigment dispersion”) is concentrated. Cy-I (mass ratio [pigment / crosslinked polymer (a')] = 8.0, pigment content 40.0%, cumulant average particle size: 95 nm) was obtained.

Production Example 3-2 to 3-4, 3-6
In Production Example 3-1 the cyan pigment dispersions Cy-II to Cy-IV and Cy- are the same except that the type of the aqueous pigment dispersion (i) and the amount of the cross-linking agent are changed as shown in Table 4. Got a VI.

Production Example 3-5
The aqueous pigment dispersion (i-2) obtained in Production Example 2-2 is concentrated under reduced pressure so that the content of the pigment in the obtained pigment dispersion is 40.0%, and the cyan pigment is dispersed. Body Cy-V was obtained.

<Manufacturing of an aqueous dispersion of polymer particles B containing no pigment (step B1)>
Production Example 4-1
100.0 parts (solid content concentration 20%) of the aqueous dispersion (D1) of the polymer particles obtained in Production Example 1-1 was placed in a glass bottle with a screw cap, and the total carboxy of the polymer (P1) as the polymer (b) was taken. Add 3.71 parts of trimethylolpropane polyglycidyl ether (EX-321) as a cross-linking agent so that 50 mol% of the group is cross-linked (cross-linking degree 50 mol%), seal the mixture, and stir with a stirrer at 70 ° C. Was heated for 5 hours. After 5 hours, the temperature is lowered to room temperature, and a needleless syringe (manufactured by Terumo Co., Ltd.) with a capacity of 25 mL equipped with a 5 μm filter (acetyl cellulose film, outer diameter: 2.5 cm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) is used. The aqueous dispersion (D1-CL1) (solid content concentration) of the crosslinked polymer particles B containing no pigment is further filtered and concentrated under reduced pressure so that the solid content concentration of the obtained aqueous dispersion becomes 40.0%. : 40.0%, average particle size of cumulant: 56 nm) was obtained.

Production Examples 4-2 to 4-2
In Production Example 4-1 in the same manner except that the type and amount of the aqueous dispersion of the polymer particles and the amount of the crosslinking agent were changed as shown in Table 5, the aqueous dispersion of the crosslinked polymer particles B containing no pigment (the aqueous dispersion of the crosslinked polymer particles B ( D2-CL1), (D2-CL2), and (D3-CL1) were obtained, respectively.

Production Example 4-5
The aqueous dispersion (D2) of the polymer particles obtained in Production Example 1-2 is concentrated under reduced pressure so that the solid content concentration of the obtained aqueous dispersion is 40.0%, and is not pigment-containing. An aqueous dispersion (D2-NCL1) of crosslinked polymer particles B was obtained.

<Manufacturing of water-in-oil emulsion ink (process I)>
Example 1
A water-in-oil emulsion ink Cy-1 was obtained by the following procedure so that the content of the pigment in the obtained water-in-oil emulsion ink was 5.0%.
12.5 parts of the cyan pigment dispersion Cy-I obtained in Production Example 3-1 and 4.5 parts of ion-exchanged water, and the pigment-free crosslinked polymer particles B obtained in Production Example 4-1. 8.5 parts of the aqueous dispersion D1-CL1 was mixed to prepare an aqueous phase component.
Separately, 51.0 parts of a hydrocarbon solvent (trade name: AF Solvent No. 4 (petroleum hydrocarbon), manufactured by JXTG Energy Co., Ltd.) as a water-insoluble organic solvent, and an ester solvent (trade name: Exepearl M-OL) (Methyl oleate), 18.5 parts made by Kao Co., Ltd., and 5.0 parts of sucrose hydrocarbon acid ester (trade name: Ryoto Sugar Ester ER-290, manufactured by Mitsubishi Chemical Foods Co., Ltd.) as an emulsifier. Was mixed to prepare an oil phase component.
Using a homogenizer (trade name: ULTLRA-TURRAX, model: T25 digital, shaft generator (model: S25N-25F), all manufactured by IKA Japan Co., Ltd.), the oil phase component is adjusted at 5,000 rpm. The aqueous phase component was added dropwise with stirring. After completion of the dropping, the mixture was stirred at 12,000 rpm for 3 minutes to obtain a water-in-oil emulsion ink Cy-1 (average particle size of emulsion: 1.1 μm).

Examples 2 to 13 and Comparative Example 1
In Example 1, each water-in-oil emulsion ink was obtained in the same manner except that the type or amount of the aqueous phase component and each component constituting the oil phase component was changed as shown in Table 6.

<Evaluation test of water-in-oil emulsion ink>
The emulsion inks obtained in Examples and Comparative Examples were used to evaluate storage stability and fixability. The results are shown in Table 6.

[Evaluation of storage stability]
The obtained emulsion ink is placed in a 100 mL screw vial and stored at 23 ° C and 60 ° C, respectively, and the state of separation of the oil phase and the aqueous phase of the emulsion ink after standing and the presence or absence of aggregated sediment are visually observed. And evaluated according to the following criteria.
(Evaluation criteria)
A: After storage for 1 week, there was no separation and coagulation sediment of the oil phase and aqueous phase of the emulsion ink at both storage temperatures of 23 ° C and 60 ° C.
B: After storage at 23 ° C for 1 week, there was no separation or coagulation sedimentation of the oil phase and aqueous phase, but for those stored at 60 ° C, the oil phase and water phase of the emulsion ink were separated or coagulated and settled. There was a thing.
C: After storage at 23 ° C, there was no separation or coagulation sedimentation of the oil phase and aqueous phase, but those stored at 60 ° C. separated or coagulated sedimentation of the oil phase and aqueous phase of the emulsion ink. Things were slightly confirmed.
D: One hour after the preparation of the emulsion ink, there was a separation or coagulation sediment of the oil phase and the aqueous phase.
If the above evaluation criteria are A or B, it is suitable for actual use. When the above evaluation standard is C, it can withstand actual use. If the above evaluation criterion is D, it may be difficult to actually use it.

[Evaluation of fixability]
The obtained emulsion ink is filled in an inkjet printer (trade name: Business Printer PX-105, manufactured by Seiko Epson Corporation), and under an environment of room temperature of 23 ° C. and relative humidity of 50% RH, plain paper (trade name: Xerox Business). A 1 cm x 1 cm solid image was printed on 4200 copy paper (manufactured by Fuji Xerox Co., Ltd.). After 5 minutes have passed after printing, a load of 700 g is applied to the cellulose non-woven fabric "Bencot (registered trademark) M3-II" (manufactured by Asahi Kasei Corporation) using the bottom surface of the weight (bottom area 50 cm ² ) to cover the printed surface 5 I rubbed it back and forth. The fixability of the image was evaluated according to the following criteria based on the degree of stain of the ink transferred to the cellulose non-woven fabric. The evaluation results are shown in Table 1.
(Evaluation criteria)
A: There was no stain on the cellulose non-woven fabric.
B: There was almost no stain on the cellulose non-woven fabric.
C: The non-woven fabric made of cellulose was slightly dirty, but it was at a level where there was no problem in actual use.
D: The cellulose non-woven fabric was dirty.
E: The cellulose non-woven fabric was significantly soiled.
If the above evaluation criteria are A or B, it is suitable for actual use. When the above evaluation standard is C, it is a level that can be actually used. If the above evaluation criterion is D, inconvenience may occur in actual use. When the above evaluation standard is E, it is difficult to actually use it.

From Table 6, it can be seen that Examples 1 to 13 have a level at which storage stability can be actually used, and further, the fixability is improved as compared with Comparative Example 1.

According to the emulsion ink of the present invention and the method for producing the emulsion ink, it is possible to obtain a printed matter having good storage stability and excellent fixability. Further, the emulsion ink of the present invention is useful for inkjet recording.

Claims (11)

A water-in-oil emulsion ink having an aqueous phase in the oil phase.
The aqueous phase contains a pigment, a polymer dispersant A, and polymer particles B containing no pigment.
A water-in-oil emulsion ink in which the oil phase contains a water-insoluble organic solvent and an emulsifier. Claimed that the mass ratio of the content of the polymer particles B containing no pigment to the content of the pigment in the water-in-oil emulsion ink [polymer particles B without pigment / pigment] is 0.05 or more and 1.5 or less. Item 2. The water-in-oil emulsion ink according to Item 1. The water-in-oil emulsion ink according to claim 1 or 2, wherein the polymer constituting the polymer dispersant A and the polymer particles B containing no pigment contains an acid group, respectively. The water-in-oil type according to claim 3, wherein at least a part of each acid group of the polymer constituting the polymer dispersant A and the polymer particles B containing no pigment is neutralized with an alkali metal hydroxide. Emulsion ink. The water-in-oil emulsion ink according to any one of claims 1 to 4, which comprises a crosslinked structure in which the polymer constituting the polymer dispersant A and the polymer particles B containing no pigment are crosslinked with a crosslinking agent, respectively. The fifth aspect of the present invention, wherein the polymer dispersant A is a crosslinked polymer (a') in which a non-crosslinked polymer (a) is crosslinked with a crosslinking agent, and the acid value of the crosslinked polymer (a') is 40 mgKOH / g or more. The water-in-oil emulsion ink described. The water-in-oil emulsion ink according to any one of claims 1 to 6, wherein the content of water in the water-in-oil emulsion ink is 5% by mass or more and 30% by mass or less. The water-in-oil emulsion ink according to any one of claims 1 to 7, which is used for inkjet recording. The method for producing a water-in-oil emulsion ink according to any one of claims 1 to 8, which comprises the following step I.
Step I: Includes an aqueous phase component containing an aqueous pigment dispersion in which the pigment is dispersed in an aqueous medium with a polymer dispersant A, an aqueous dispersion of polymer particles B containing no pigment, and a water-insoluble organic solvent and emulsifier. A process of mixing and emulsifying an oil phase component to obtain a water-in-oil emulsion ink. The polymer dispersant A is a crosslinked polymer (a') in which a non-crosslinked polymer (a) is crosslinked with a crosslinking agent.
The method for producing a water-in-oil emulsion ink according to claim 9, wherein the water-based pigment dispersion used in step I is obtained by a method including the following steps A1-1, A1 and A2.
Step A1-1: Part of the acid group of the polymer (a) is neutralized with a neutralizing agent to obtain an aqueous dispersion of the polymer (a) particles. Step A1: The polymer obtained in the step A1-1 (step A1: a) A step of dispersing a pigment mixture containing an aqueous dispersion of particles and a pigment to obtain an aqueous pigment dispersion in which the pigment is dispersed in an aqueous medium with a polymer (a). Step A2: Obtained in step A1. A step of adding a cross-linking agent to an aqueous pigment dispersion and cross-linking the polymer (a) with the cross-linking agent to obtain an aqueous pigment dispersion in which the pigment is dispersed with the cross-linked polymer (a'). The pigment-free polymer particles B are composed of a crosslinked polymer (b') in which a non-crosslinked polymer (b) is crosslinked with a crosslinking agent.
The method for producing a water-in-oil emulsion ink according to claim 9 or 10, wherein the aqueous dispersion of the polymer particles B containing no pigment used in the step I is obtained by the method including the following steps B1-1 and B1. ..
Step B1-1: Part of the acid group of the polymer (b) is neutralized with a neutralizing agent to obtain an aqueous dispersion of the polymer (b) particles. Step B1: The polymer obtained in the step 1-1 (step B1: b) A cross-linking agent is added to the aqueous dispersion of the particles, and the polymer (b) is cross-linked with the cross-linking agent to obtain a pigment-free aqueous dispersion of the polymer particles B composed of the cross-linked polymer (b'). Obtaining process