JP7512834B2 - Treatment liquid and ink set, image forming method, and image forming apparatus - Google Patents

Description

The present invention relates to a treatment liquid and ink set, an image forming method, and an image forming apparatus.

Conventionally, absorbent recording media such as plain paper have generally been used as printing targets for inkjet recording methods. However, in recent years, printing targets have become more diverse. For example, there is a demand for coated paper with low ink absorbency and non-ink-absorbent plastic films such as food packaging materials to have image quality equal to or greater than that of conventional recording media, and for higher printing speeds.
However, on recording media with low ink absorption or no ink absorption, the ink droplets that land on the recording medium do not penetrate the recording medium and remain on the surface for a long time, which means that the droplets are likely to gather together in solid areas of the image, causing patchy density unevenness (beading), and there is a problem that the adhesion at the interface between the recording medium and the ink coating is insufficient, causing the image surface to peel off due to friction.

In order to solve the above problems, a photocurable ink composition has been proposed that contains, for example, a colorant, water, a photoinitiator, a UV-curable polyurethane dispersion, and a hydrophobic radiation-curable monomer, and that can produce a highly scratch-resistant image by undergoing a radical reaction (see, for example, Patent Document 1).

The present invention aims to provide an image forming method that can prevent the occurrence of beading and form images that are excellent in abrasion resistance and gloss.

The image forming method of the present invention as a means for solving the above problems includes a treatment liquid application step of applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium, an ink application step of applying an ink containing water, a coloring material, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image, an active energy ray irradiation step of irradiating the image with active energy rays, and a drying step of heating and drying the image after irradiation.

The present invention provides an image forming method that can prevent beading and form images with excellent abrasion resistance and gloss.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus used in the image forming method of the present invention.

(Image forming method and image forming apparatus)
The image forming method of the present invention includes a treatment liquid applying step of applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium, an ink applying step of applying an ink containing water, a colorant, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image, an active energy ray irradiation step of irradiating the image with active energy rays, and a drying step of heating and drying the irradiated image, and further includes other steps as necessary.

The image forming apparatus of the present invention has a treatment liquid applying means for applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium, an ink applying means for applying an ink containing water, a coloring material, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image, an active energy ray irradiation means for irradiating the image with active energy rays, and a drying means for heating and drying the image after irradiation, and further has other means.

The image forming method of the present invention can be suitably carried out by the image forming apparatus of the present invention, and the treatment liquid application step can be carried out by a treatment liquid application means, the ink application step can be carried out by an ink application means, the active energy ray irradiation step can be carried out by an active energy ray irradiation means, the drying step can be carried out by a drying means, and the other steps can be carried out by other means.

Conventional technology has the problem that when using coated paper with low ink absorption or non-ink-absorbent plastic films such as food packaging materials, the adhesion between the recording medium and the ink coating is weak, making it difficult to obtain sufficient abrasion resistance.

Therefore, in the present invention, by including a treatment liquid application step of applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium, an ink application step of applying an ink containing water, a colorant, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied to form an image, an active energy ray irradiation step of irradiating the image with active energy rays, and a drying step of heating and drying the image after irradiation, it is possible to prevent the occurrence of beading and form an image with excellent abrasion resistance and gloss. This is even more noticeable during high-speed printing.

The following describes the treatment liquid, ink, and treatment liquid/ink set used in the image forming method and image forming apparatus of the present invention.

(Processing solution)
The treatment liquid of the present invention contains a nonionic resin, a polyvalent metal salt, and water, and further contains other components as necessary. The treatment liquid may also be called a "pretreatment liquid," a "pre-coating liquid," or an "undercoat liquid."

<Nonionic resin>
The nonionic resin used in the treatment liquid of the present invention is preferably a resin having a nonionic hydrophilic site in the side chain of the molecule of the resin from the viewpoint of dispersion stability. As the nonionic resin, it is preferable to use nonionic resin particles made of nonionic resin. The nonionic resin particles are dispersed in water or the like as a dispersion medium in the form of a resin emulsion, and can be mixed with materials such as coloring material and organic solvent to obtain a treatment liquid.
The nonionic resin particles are fine resin particles obtained by a method such as emulsion polymerization using materials containing mainly monofunctional monomers having polymerizability, an emulsifier, a polymerization initiator, a crosslinking agent, and the like.
The nonionic resin preferably contains a structural unit represented by the following general formula (1) from the viewpoint of improving dispersion stability and abrasion resistance.

ただし、前記一般式（１）中、Ｒ_１は－ＣＯＯ－を表し、Ｒ_２及びＲ_３は水素原子又は炭素数１～４のアルキル基を表す。
Ｒ_２及びＲ_３における炭素数１～４のアルキル基としては、例えば、メチル基、エチル基、プロピル基、ブチル基などが挙げられる。Ｒ_３がメチル基であると、保存安定性が向上するため好ましい。Ｒ_２は水素原子又はメチル基が好ましく、メチル基がより好ましい。

In the general formula (1), R ₁ represents —COO—, and R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
Examples of the alkyl group having 1 to 4 carbon atoms in _R2 and _R3 include a methyl group, an ethyl group, a propyl group, and a butyl group. _R3 is preferably a methyl group because storage stability is improved. _R2 is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.

In the structural unit represented by the above general formula (1), n is preferably an integer of 5 or more and 100 or less, and more preferably an integer of 10 or more and 50 or less. If n is less than 5, the steric repulsion due to the structure represented by the above general formula (1) is insufficient, and the treatment liquid is more likely to aggregate due to the salts present in the treatment liquid, which may result in poor storage stability. If n is more than 100, hydrophilicity increases, and water resistance may decrease when the treatment liquid forms a coating film.

In the nonionic resin of the present invention, there is no particular limitation on the structure other than the structure represented by the above general formula (1), and any known resin that can be copolymerized with the structural unit represented by the above general formula (1) can be appropriately selected.
Examples of such resins include urethane resins, polyester resins, acrylic resins, vinyl acetate resins, styrene resins, butadiene resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, acrylic-silicone resins, etc. These may be used alone or in combination of two or more.
Among these, at least one resin selected from acrylic resins, urethane resins, and polyester resins is preferred because the glass transition temperature can be controlled relatively easily and the resins have excellent dispersion stability and abrasion resistance.

The nonionic resin contains a monomer unit derived from a monomer and a crosslinking unit derived from a crosslinking agent, and when the total of the monomer unit derived from the monomer and the crosslinking unit derived from the crosslinking agent is 100 parts by mass, it preferably contains 1 part by mass or more and 20 parts by mass or less of the structural unit represented by the above general formula (1), more preferably 2 parts by mass or more and 15 parts by mass or less, and even more preferably 4 parts by mass or more and 10 parts by mass or less. When the content of the structural unit represented by the above general formula (1) is 1 part by mass or more, the storage stability is improved due to the steric repulsion caused by the structural unit represented by the above general formula (1). In addition, when the content of the structural unit represented by the above general formula (1) is 20 parts by mass or less, the abrasion resistance is improved.

The content of the structural unit represented by the above general formula (1) is preferably 8% by mass or more and 20% by mass or less when the number of repeating units in the general formula (1) is n = 5 to 10. In the general formula (1), the content is preferably 4% by mass or more and 10% by mass or less when the number of repeating units in the general formula (1) is n = 11 to 40. In the general formula (1), the content is preferably 1% by mass or more and 8% by mass or less when the number of repeating units in the general formula (1) is n = 41 to 100, because this allows both the effect of storage stability and the scratch resistance of the coating film to be achieved.

The nonionic resin may have a crosslinked structure. For example, a crosslinking agent is added during the production of resin particles to obtain resin particles having a crosslinked structure. An ethylenically unsaturated compound may be used in combination with the crosslinking agent. Specific examples of ethylenically unsaturated compounds include hydrolyzable alkoxysilyl group-containing ethylenically unsaturated compounds (e.g., vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinyl(2-methoxyethoxy)silane, vinyltriacetoxysilane, etc.), polyfunctional vinyl compounds (divinylbenzene, diallylphthalate, etc.), etc. These may be used alone or in combination of two or more.

An emulsifier may be used when producing the nonionic resin particles. There are no particular limitations on the emulsifier used, and any known emulsifier may be used as appropriate depending on the purpose. Examples of commercially available emulsifiers include SE-10N, NE-10, NE-20, NE-30, ADEKA REASOAP SR-10, ADEKA REASOAP SR-20, and ADEKA REASOAP ER-20 (all manufactured by ADEKA Corporation); AQUALON RN-10, AQUALON RN-20, AQUALON RN-50, AQUALON HS-10, AQUALON KH-05, and AQUALON KH-10 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.); ELEMINOL JS-2 (manufactured by Sanyo Chemical Industries Co., Ltd.), and LATEMUL S-180 (manufactured by Kao Corporation). These may be used alone or in combination of two or more types.

A polymerization initiator may be used when producing the nonionic resin particles. Examples of the polymerization initiator include peroxides such as ammonium persulfate, potassium persulfate, hydrogen peroxygen, and tert-butyl hydroperoxide, or redox initiators consisting of combinations of these peroxides with metal ions, reducing agents such as ascorbic acid, and azo compounds such as 2,2'-azobisisobutyronitrile. These may be used alone or in combination of two or more.

As a method for producing resin particles containing a resin having a structural unit represented by the above general formula (1), for example, an emulsion obtained by stirring a monomer that becomes the structural unit represented by the above general formula (1), a monomer that becomes another structural unit, a crosslinking agent, an emulsifier, etc., is dropped into an aqueous phase containing a polymerization initiator to perform emulsion polymerization, thereby obtaining resin particles. Note that the polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen gas.

Examples of monomers that can be used as structural units represented by the above general formula (1) include polyethylene glycol (n=5 to 100) monomethacrylate, methoxypolyethylene glycol (n=5 to 100) monomethacrylate, ethoxypolyethylene glycol (n=5 to 100) monomethacrylate, polyethylene glycol (n=5 to 100) monoacrylate, and methoxypolyethylene glycol (n=5 to 100) monoacrylate.
As the monomer that becomes the structural unit represented by the above general formula (1), a commercially available product can be used. Examples of the commercially available product include Blemmer AME-400, Blemmer PME-100, Blemmer PME-200, Blemmer PME-400, Blemmer PME-1000, and Blemmer PME-4000 (all manufactured by NOF Corporation).
The content of the structural unit represented by the general formula (1) in the resin particles can be calculated from the blending amount of the monomer that becomes the structural unit represented by the general formula (1).

The content of the resin particles is preferably 0.5% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, in terms of solid content, relative to the total amount of the treatment liquid. If the content is 0.5% by mass or more, the coating film sufficiently covers the substrate, improving the uniformity of the coating film, and if it is 30% by mass or less, the applicability of the treatment liquid is improved.

The fact that the nonionic resin contains a resin having a structural unit represented by the above general formula (1), and the content of the structural unit represented by the general formula (1) relative to the resin particles can be determined by structural analysis using ^13C -NMR, ^1H -NMR, pyrolysis GC or MS.
Furthermore, if the materials used in the production process and their contents are known, the content of the structural unit represented by the general formula (1) can be calculated from the contents.

The glass transition temperature of the nonionic resin in the coated state is preferably -40°C or higher and 0°C or lower. If the glass transition temperature is -40°C or higher, the coating portion of the treatment liquid is prevented from becoming sticky (tacky) after printing, improving abrasion resistance, and if the glass transition temperature is 0°C or lower, the resin particles of the treatment liquid soften, improving adhesion to the media.

The nonionic resin particles preferably have a cumulative 50% volume particle diameter (median particle diameter) _D50 in a dispersed state of 40 nm to 300 nm, more preferably 60 nm to 200 nm, and even more preferably 80 nm to 150 nm. When the cumulative 50% volume particle diameter of the resin particles is 40 nm or more, excessive thickening of the treatment liquid is easily suppressed, and when the cumulative 50% volume particle diameter is 300 nm or less, the transparency of the coating film is improved.

<Polyvalent metal salt>
The polyvalent metal salt has the function of quickly agglomerating the components in the ink after droplets land, thereby suppressing beading.
The type of polyvalent metal salt can be appropriately selected depending on the components in the ink to be aggregated. However, if the polyvalent metal in the polyvalent metal salt is one or more selected from calcium, magnesium, and aluminum, this is preferred from the viewpoint of suppressing beading because it has excellent cohesive force.

The polyvalent metal salt is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polyvalent metal salt include calcium chloride, calcium acetate, calcium iodide, magnesium chloride, magnesium acetate, magnesium nitrate, magnesium thiosulfate, magnesium iodate, magnesium sulfate, aluminum chloride, aluminum nitrate, aluminum lactate, aluminum sulfate, aluminum ammonium sulfate, aluminum potassium sulfate, and zinc chloride. These may be used alone or in combination of two or more.

The content of the polyvalent metal salt is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less, based on the total amount of the treatment liquid. If the content is 0.1% by mass or more, an effect of suppressing beading caused by aggregation of ink components during image formation using the ink is exerted. On the other hand, if the content is 20% by mass or less, the strength, adhesion, and transparency of the dried coating film are improved.

<Water>
The water is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, and ultrapure water, etc. These may be used alone or in combination of two or more kinds.
The water content is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of the drying property of the treatment liquid, the water content is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 60% by mass or less, based on the total amount of the treatment liquid.

<Other ingredients>
Examples of other components include organic solvents, surfactants, antifoaming agents, antiseptic and antifungal agents, rust inhibitors, and pH adjusters.

-Organic solvent-
The organic solvent used in the present invention is not particularly limited, and any water-soluble organic solvent can be used.
Examples of the water-soluble organic solvent include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol (propanediol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5 -pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and polyhydric alcohols such as petriol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene polyhydric alcohol alkyl ethers such as glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone; amides such as formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; amines such as 3-methoxy-3-methyl-1-butanol, monoethanolamine, diethanolamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; propylene carbonate, ethylene carbonate, and the like.
It is preferable to use an organic solvent having a boiling point of 250° C. or less, since this not only functions as a wetting agent but also provides good drying properties.

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also suitably used.
Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of the glycol ether compound include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

Polyol compounds with 8 or more carbon atoms and glycol ether compounds can improve the permeability of ink when paper is used as the recording medium.

The content of the organic solvent in the treatment liquid is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less. If the content is 10% by mass or more, the wettability to the recording medium is improved, and if it is 60% by mass or less, the sharpness and drying property of the printed image are improved.

-Surfactants-
As the surfactant, any of silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used.
Silicone surfactant is not particularly limited, and can be appropriately selected according to purpose. Among them, preferred are those that do not decompose even at high pH, such as side chain modified polydimethylsiloxane, both end modified polydimethylsiloxane, one end modified polydimethylsiloxane, both end modified polydimethylsiloxane of side chain, etc., and those having polyoxyethylene group or polyoxyethylene polyoxypropylene group as modified group are particularly preferred because they show good properties as aqueous surfactants. In addition, polyether modified silicone surfactants can also be used as the silicone surfactant, such as a compound in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane.

As the fluorine-based surfactant, for example, perfluoroalkyl sulfonic acid compound, perfluoroalkyl carboxylic acid compound, perfluoroalkyl phosphate compound, perfluoroalkyl ethylene oxide adduct, and polyoxyalkylene ether polymer compound having perfluoroalkyl ether group in the side chain are particularly preferred because they have low foaming properties.As the perfluoroalkyl sulfonic acid compound, for example, perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, etc. can be mentioned.As the perfluoroalkyl carboxylic acid compound, for example, perfluoroalkyl carboxylic acid, perfluoroalkyl carboxylate, etc. can be mentioned.As the polyoxyalkylene ether polymer compound having perfluoroalkyl ether group in the side chain, for example, sulfate ester salt of polyoxyalkylene ether polymer having perfluoroalkyl ether group in the side chain, salt of polyoxyalkylene ether polymer having perfluoroalkyl ether group in the side chain, etc. can be mentioned. Examples _of counter ions _of the salts in these fluorosurfactants include Li, Na, K _{, NH4} , _NH3CH2CH2OH , _{NH2 ( CH2CH2OH} ) ₂ , and NH( _CH2CH2OH ) ₃ .
Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and polyoxyethylene alkyl ether sulfates.
These may be used alone or in combination of two or more.

The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the silicone surfactant include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end side-chain modified polydimethylsiloxane. Polyether-modified silicone surfactants having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferred because they exhibit good properties as an aqueous surfactant.
Such surfactants may be synthesized appropriately or may be commercially available products, such as those available from BYK-Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.
The polyether-modified silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, it can be one in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylpolysiloxane, as represented by the general formula (S-1).

（但し、前記一般式（Ｓ－１）式中、ｍ、ｎ、ａ、及びｂは、それぞれ独立に、整数を表し、Ｒは、アルキレン基を表し、Ｒ’は、アルキル基を表す。）

(In the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R′ represents an alkyl group.)

As the polyether-modified silicone surfactant, commercially available products can be used, such as KF-618, KF-642, KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (manufactured by Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (manufactured by Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (manufactured by BYK-Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (manufactured by Toshiba Silicon Co., Ltd.), etc.

The fluorine-based surfactant is preferably a compound having 2 to 16 fluorine-substituted carbon atoms, and more preferably a compound having 4 to 16 fluorine-substituted carbon atoms.
Examples of the fluorine-based surfactant include perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains.
Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferred because they have little foaming property, and in particular, fluorine-based surfactants represented by any one of general formula (F-1) and general formula (F-2) are preferred.

上記一般式（Ｆ－１）で表される化合物において、水溶性を付与するためにｍは０～１０の整数が好ましく、ｎは０～４０の整数が好ましい。

In the compound represented by the above general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility.

[General formula (F-2)]
_{CnF2n + -CH2CH} (OH)CH2 _- O- _{(CH2CH2O ) a} -Y
In the compound represented by the above general formula (F-2), Y is H or C _m F _2m+1 , m is an integer from 1 to 6, or CH ₂ CH(OH)CH ₂ -C _m F _2m+1 , m is an integer from 4 to 6, or C _p H _2P+1 , and p is an integer from 1 to 19. n is an integer from 1 to 6. a is an integer from 4 to 14.

As the fluorosurfactant, commercially available products may be used. Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, and FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F-1405, and F-474 (all manufactured by DIC Corporation); and Zonyl TBS, FSP, FSA, and FSN-100. , FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours Corporation); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and the like. Among these, Chemours' FS-3100, FS-34, and FS-300, Neos' FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW, Omnova's Polyfox PF-151N, and Daikin Industries, Ltd.'s Unidyne DSN-403N are particularly preferred because they provide good print quality, particularly improved color development, penetration into paper, wettability, and dye uniformity.

The content of the surfactant is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of improving wettability and image quality, it is preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.05% by mass or more and 5% by mass or less.

- Defoaming agent -
The defoaming agent is not particularly limited, and examples thereof include silicone-based defoaming agents, polyether-based defoaming agents, and fatty acid ester-based defoaming agents. These may be used alone or in combination of two or more. Among these, silicone-based defoaming agents are preferred because of their excellent foam breaking effect.

- Antiseptic and fungicide -
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

-anti-rust-
The rust inhibitor is not particularly limited, and examples thereof include acid sulfite, sodium thiosulfate, and 1,2,3-benzotriazole.

- pH adjuster -
There are no particular limitations on the pH adjuster, so long as it is capable of adjusting the pH to 7 or higher, and examples of the pH adjuster include amines such as diethanolamine and triethanolamine.

<Ink>
The ink used in the present invention contains water, a coloring material, and a polymerizable compound, and preferably contains a polymerization initiator, and further contains other components as necessary. By containing the polymerizable compound, the ink significantly improves the scratch resistance of the ink coating film by aggregation or curing reaction due to irradiation with active energy rays.

<<Polymerizable Compound>>
The polymerizable compound contains at least one of a dispersion having a polymerizable group and a polymerizable monomer, and may contain other materials as necessary.

- Dispersion having polymerizable group (reactive dispersion) -
The dispersion having a polymerizable group is a reactive particle capable of undergoing a polymerization reaction with other particles by stimulation of ultraviolet light, heat, etc. By including a dispersion having a polymerizable group in a curable composition, it is possible to provide a cured film obtained by curing the ink with excellent smoothness (glossiness), flexibility, and abrasion resistance.
The dispersion having a polymerizable group is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include dispersions having a water-dispersible polymerizable group. Examples of the dispersions having a water-dispersible polymerizable group include reactive polyurethane particles. Examples of the reactive polyurethane particles include (meth)acrylated polyurethane particles.

The (meth)acrylated polyurethane particles may be, for example, commercially available products. Examples of commercially available products include Ucecoat (registered trademark) 6558 (manufactured by Daicel-Allnex Corporation), Ucecoat (registered trademark) 6559 (manufactured by Daicel-Allnex Corporation), Ebecryl (registered trademark) 2002 (manufactured by Daicel-Allnex Corporation), Ebecryl (registered trademark) 2003 (manufactured by Daicel-Allnex Corporation), Ucecoat (registered trademark) 7710 (manufactured by Daicel-Allnex Corporation), and Ucecoat (registered trademark) 7720 (manufactured by Daicel-Allnex Corporation). (registered trademark) 7655 (manufactured by Daicel Allnex Corporation), NeoradR (registered trademark) 440 (manufactured by Avecia Corporation), NeoradR (registered trademark) 441 (manufactured by Avecia Corporation), NeoradR (registered trademark) 447 (manufactured by Avecia Corporation), NeoradR (registered trademark) 448 (manufactured by Avecia Corporation), Bayhydrol (registered trademark) UV2317 (manufactured by COVESTRO Corporation), Bayhydrol (registered trademark) UV Examples of the VP LS2348 include VP LS2348 (manufactured by COVESTRO), Lux (registered trademark) 430 (manufactured by ALBERDING BOLEY), Lux (registered trademark) 399 (manufactured by ALBERDING BOLEY), Lux (registered trademark) 484 (manufactured by ALBERDING BOLEY), Laromer (registered trademark) LR8949 (manufactured by BASF), Laromer (registered trademark) LR8983 (manufactured by BASF), Laromer (registered trademark) PE22WN (manufactured by BASF), Laromer (registered trademark) PE55WN (manufactured by BASF), and Laromer (registered trademark) UA9060 (manufactured by BASF). These may be used alone or in combination of two or more types.
Among these, Laromer (registered trademark) LR8949 (manufactured by BASF Corporation) and Laromer (registered trademark) LR8983 (manufactured by BASF Corporation) are preferred because they can improve abrasion resistance.

The content of the dispersion having a polymerizable group is preferably 2% by mass or more and 12% by mass or less, and more preferably 6% by mass or more and 12% by mass or less, in terms of solid content, relative to the total amount of ink. If the content of the dispersion having a polymerizable group is 2% by mass or more and 12% by mass or less, the scratch resistance of the ink film can be improved.

-Polymerizable monomer-
The polymerizable monomer is not particularly limited as long as it has a reactive substituent capable of undergoing a polymerization reaction, and can be appropriately selected depending on the purpose.
As the polymerizable monomer, for example, (meth)acrylate, (meth)acrylamide, vinyl ether, etc. can also be used in combination. More specifically, for example, 4-hydroxybutyl (meth)acrylate, ethylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, γ-butyrolactone acrylate, isobornyl (meth)acrylate, formalized trimethylolpropane mono(meth)acrylate, polytetramethylene glycol di(meth)acrylate, trimethylolpropane (meth)acrylic acid benzoate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate [CH ₂ ═CH—CO—(OC ₂ H ₄ ) _n -OCOCH═CH ₂ (n≒4)], polyethylene glycol di(meth)acrylate [CH ₂ ═CH—CO—(OC ₂ H ₄ ) _n -OCOCH═CH ₂ (n≒4)], (n≈9)], polyethylene glycol di(meth)acrylate [CH ₂ ═CH-CO-(OC ₂ H ₄ ) _n -OCOCH═CH ₂ (n≈14)], polyethylene glycol di(meth)acrylate [CH ₂ ═CH-CO-(OC ₂ H ₄ ) _n -OCOCH═CH ₂ (n≈23)], dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol dimethacrylate [CH ₂ ═C(CH ₃ )-CO-(OC ₃ H ₆ ) _n -OCOC(CH ₃ )=CH ₂ (n≒7)], 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, propylene oxide modified bisphenol A di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, (meth)acryloylmorpholine, propylene oxide modified tetramethylolmethane tetra(meth)acrylate, Dipentaerythritol hydroxypenta(meth)acrylate, caprolactone-modified dipentaerythritol hydroxypenta(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(2-hydroxyethylene (meth)isocyanurate tri(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, propylene oxide modified neopentyl glycol di(meth)acrylate, propylene oxide modified glyceryl tri(meth)acrylate, polyester di(meth)acrylate, polyester tri(meth)acrylate, polyester tetra(meth)acrylate, polyester penta(meth)acrylate, polyester poly(meth)acrylate, polyurethane di(meth)acrylate, polyurethane tri(meth)acrylate, polyurethane tetra Examples of such compounds include (meth)acrylate, polyurethane penta(meth)acrylate, polyurethane poly(meth)acrylate, 2-hydroxypropyl(meth)acrylamide, N-vinylcaprolactam, N-vinylpyrrolidone, N-vinylformamide, cyclohexane dimethanol monovinyl ether, cyclohexane dimethanol divinyl ether, hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, diethylene glycol divinyl ether, dicyclopentadiene vinyl ether, tricyclodecane vinyl ether, benzyl vinyl ether, and ethyloxetane methyl vinyl ether. These compounds may be used alone or in combination of two or more. Among these compounds, a compound may be selected and added in consideration of the solubility in water as a dispersion medium, the viscosity of the composition, the thickness of the cured film (coating film) on the substrate, and the like.

The content of the polymerizable monomer is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the total amount of the ink. If the content of the polymerizable monomer is 1% by mass or more and 20% by mass or less, the scratch resistance of the ink film can be improved.

<Polymerization initiator>
The ink may contain a polymerization initiator. The polymerization initiator may be any one that can generate active species such as radicals or cations by the energy of active energy rays and initiate polymerization of a polymerizable compound (monomer or oligomer). As such a polymerization initiator, known radical polymerization initiators, cationic polymerization initiators, base generators, etc. may be used alone or in combination of two or more kinds, and among them, it is preferable to use a radical polymerization initiator.
The content of the polymerization initiator is preferably from 1% by mass to 10% by mass based on the total amount of the ink in order to obtain a sufficient curing speed.
Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

In addition to the polymerization initiator, a polymerization accelerator (sensitizer) can also be used in combination. The polymerization accelerator is not particularly limited, but is preferably, for example, an amine compound such as trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, 2-ethylhexyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, or 4,4'-bis(diethylamino)benzophenone, and the content thereof may be appropriately set depending on the polymerization initiator used and its amount.
Particularly preferred are water-soluble polymerization initiators, and photopolymerization initiators having a hydroxyl group in the molecule are preferred. The photopolymerization initiator skeleton is preferably an alkylphenone-based or monoacylphosphine oxide-based polymerization initiator.

<Coloring material>
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, inorganic pigments or organic pigments can be used. These can be used alone or in combination of two or more. Mixed crystals can also be used.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments.
Examples of inorganic pigments that can be used include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method.
Examples of organic pigments that can be used include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments for black colors include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (C.I. Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (C.I. Pigment Black 1).
Further, for color, C.I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 (Red ochre), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38, C.I. Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63, C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, and 36.

The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. One type of dye may be used alone, or two or more types may be used in combination.
Examples of the dyes include C.I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. Acid Red 52, 80, 82, 249, 254, 289, C.I. Acid Blue 9, 45, 249, C.I. Acid Black 1, 2, 24, 94, C.I. Food Black 1, 2, C.I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. Reactive Red 14, 32, 55, 79, 249, C.I. Reactive Black 3, 4, 35 and the like.

The content of colorant in the ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, from the viewpoints of improving image density, good fixing property and ejection stability.

Methods for dispersing a pigment in an ink include a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant.
As a method for making a pigment into a self-dispersing pigment by introducing a hydrophilic functional group, for example, a self-dispersing pigment that can be dispersed in water by adding a functional group such as a sulfone group or a carboxyl group to a pigment (e.g., carbon) can be used.
As a method for coating the surface of a pigment with a resin and dispersing it, a method for encapsulating the pigment in a microcapsule and dispersing it in water can be used. This can be called a resin-coated pigment. In this case, it is not necessary for all the pigments blended in the ink to be coated with a resin, and uncoated or partially coated pigments may be dispersed in the ink as long as the effects of the present invention are not impaired.
Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a polymeric dispersant, typified by a surfactant.
As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Oil Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as dispersants.
The dispersants may be used alone or in combination of two or more.

<Pigment Dispersion>
It is possible to obtain ink by mixing a pigment with materials such as water or an organic solvent, or it is also possible to manufacture ink by mixing a pigment with other materials such as water and a dispersant to prepare a pigment dispersion, and then mixing the resulting mixture with materials such as water or an organic solvent.
The pigment dispersion is obtained by dispersing water, a pigment, a pigment dispersant, and other components as required, and adjusting the particle size. Dispersion is preferably performed using a dispersing machine.
There are no particular restrictions on the particle size of the pigment in the pigment dispersion. However, in terms of the maximum number, the maximum frequency is preferably from 20 nm to 500 nm, and more preferably from 20 nm to 150 nm, in order to improve the dispersion stability of the pigment and the image quality, such as ejection stability and image density.
The particle size of the pigment can be measured, for example, using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of obtaining good ejection stability and increasing image density, the content of the pigment is preferably from 0.1% by mass to 50% by mass, and more preferably from 0.1% by mass to 30% by mass.
It is preferable that the pigment dispersion is degassed, if necessary, by filtering coarse particles using a filter, a centrifugal separator, or the like.

<<Other ingredients>>
The other components are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include water, organic solvents, surfactants, defoamers, antiseptic/antifungal agents, rust inhibitors, pH adjusters, etc. These may be the same as the water, organic solvents, surfactants, defoamers, antiseptic/antifungal agents, rust inhibitors, and pH adjusters in the treatment liquid of the present invention.

The ink can be prepared by dispersing or dissolving each of the components in, for example, water as a solvent, and further mixing the components by stirring as necessary.
For the stirring and mixing, for example, a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like can be used.

The physical properties of the ink are not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are within the following ranges.
The viscosity of the ink at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, and more preferably 5 mPa·s or more and 25 mPa·s or less, in terms of improving the print density and character quality and obtaining good ejection properties. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L, manufactured by Toki Sangyo Co., Ltd.). The measurement conditions are 25°C, a standard cone rotor (1°34'×R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN/m or less, and more preferably 32 mN/m or less at 25° C., in order to ensure that the ink is appropriately leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably from 7 to 12, and more preferably from 8 to 11, from the viewpoint of preventing corrosion of metal members that come into contact with the ink.

(Set of treatment liquid and ink)
The treatment liquid and ink set of the present invention comprises the treatment liquid of the present invention and an ink containing water, a colorant, a polymerization initiator, and a polymerizable compound.
It is preferable that the treatment liquid does not contain a compound equivalent to the polymerization initiator of the ink, since this improves the reaction efficiency by irradiation with active energy after the ink is applied, and improves abrasion resistance by reducing the remaining amount of polymerization initiator.

<Treatment liquid application step and treatment liquid application means>
The treatment liquid application step is a step of applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto the recording medium, and is carried out by a treatment liquid application device.
The resin in the treatment liquid is preferably a nonionic resin, and more preferably contains a structural unit represented by the above general formula (1).

The treatment liquid in the present invention is applied to the recording surface of the recording medium prior to the ink application process. In the treatment liquid application process, the treatment liquid is applied to at least a part or the entire image formed on the recording medium, and can be appropriately selected depending on the purpose.

The application means is not particularly limited and can be appropriately selected depending on the purpose. Examples include film coating devices such as roll coaters, flexo coaters, rod coaters, blades, wire bars, air knives, curtain coaters, slide coaters, doctor knives, screen coaters, gravure coaters (e.g., offset gravure coaters, etc.), slot coaters, and extrusion coaters. Such devices can be used in well-known methods such as forward and reverse roll coating, offset gravure, curtain coating, lithographic coating, screen coating, and gravure coating. Application can also be made by non-contact methods such as spraying and inkjet methods.

-recoding media-
The recording medium used in the present invention is not particularly limited, but includes plain paper, glossy paper, special paper, cloth, film, OHP sheet, general-purpose printing paper, etc. Furthermore, it is not limited to those used as general inkjet recording media, and may be appropriately selected and used, such as cardboard, building materials such as wallpaper and flooring, concrete, cloth for clothing such as T-shirts, textiles, leather, etc.

<Ink application step and ink application unit>
The ink application step is a step of applying an ink containing water, a coloring material, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image, and is carried out by an ink application unit.
The ink preferably contains a polymerization initiator.

Various methods can be used as ink application means, but the inkjet method is preferred. Known inkjet methods include the line head method and the serial head method. The line head method corresponds to the main scanning direction by moving the recording medium, and the sub-scanning direction by arranging the head in a line, continuously moving the recording medium, and ejecting ink from the recording head held in a fixed position onto the recording medium to form an image. The serial head method corresponds to scanning in the sub-scanning direction by moving the recording medium by moving the recording head back and forth in the main scanning direction, which is the direction in which the nozzles are arranged side by side. In both methods, the recording head relatively scans the recording medium to eject liquid. In the present invention, the line head method is preferred because it is characterized by performing the above four steps continuously.

There are no particular limitations on the other inkjet head types and they can be selected appropriately depending on the purpose. For example, continuous ejection type, on-demand type, etc. are included. On-demand types include the piezo type, thermal type, electrostatic type, etc., but the piezo type is preferable from the viewpoint of ejection reliability.

The size of the ink droplets is preferably, for example, 1 pL to 30 pL, the ejection speed is preferably 5 m/s to 20 m/s, the drive frequency is preferably 1 kHz or more, and the resolution is preferably 300 dpi or more.Furthermore, it is preferable that the recording head has a large number of nozzles and has either a head part or a recording unit that turns the ink in the ink set into ink droplets by the action of energy and ejects them.
It is preferable that the recording head comprises a liquid chamber, a fluid resistance portion, a vibration plate, and a nozzle member, and that at least a part of the recording head is formed from a material containing either silicone or nickel.
The nozzle diameter of the recording head is preferably 30 μm or less, and more preferably 1 μm or more and 20 μm or less.

<Active energy ray irradiation step and active energy ray irradiation means>
The active energy ray irradiation step is a step of irradiating the image with active energy rays, and is carried out by an active energy ray irradiation means.

The active energy rays used to cure the ink used in the present invention may be ultraviolet rays, electron beams, α rays, β rays, γ rays, X-rays, etc., as long as they can provide the energy required to promote the polymerization reaction of the polymerizable components in the ink, and are not particularly limited. However, from the viewpoint of curability, it is preferable to use ultraviolet rays.

As the ultraviolet light source, for example, a low pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, a hot cathode tube, a cold cathode tube, an LED, etc. can be used, but it is preferable to use a metal halide lamp because it is effective as a light source for curing the treatment liquid due to its wide wavelength range. As the metal halide, a metal halide such as Pb, Sn, Fe, etc. is used, and it can be appropriately selected according to the absorption spectrum of the photoinitiator.
Any lamp that is effective for curing can be used without any particular limitation. In the case of a UV irradiation lamp, heat is generated, which may cause deformation of the recording medium, so it is preferable that a cooling mechanism, such as a cold mirror, a cold filter, or a workpiece cooling mechanism, is provided.

From the viewpoint of curability, the illuminance of the metal halide lamp is preferably 0.1 W/cm ² or more and 150 W/cm ² or less. When used for curing ink, irradiation is preferably performed so that the cumulative amount of UV-A light is 17 mJ/cm ² or more and 2000 mJ/cm ² or less, and more preferably 200 mJ/cm ² or more and 2000 mJ/cm ² or less. By irradiating the ink with an cumulative amount of UV-A of 17 mJ/cm ² or more, the ink film is sufficiently cured, and bleeding during application of the treatment liquid can be prevented. Furthermore, by irradiating the ink with an cumulative amount of UV-A of 2000 mJ/cm ² or less, adverse effects on the recording medium, such as burning of the recording medium, can be suppressed.

<Drying step and drying means>
The drying step is a step of heating and drying the irradiated image, and is carried out by a drying means.
In the drying process, heat drying using a heat source is useful. As the heating means, one capable of uniformly heating the recording surface is preferable. For example, a hot air drying heater by blowing hot air (hot air) onto the printing surface, drum drying by warming a drum roller in contact with the recording medium, and other heaters such as nichrome wire heaters, halogen heaters, ceramic heaters, and carbon heaters can be appropriately selected by combining one or more of them according to the purpose, but are not limited thereto. Among these, a hot air drying heater is preferable from the viewpoint of improving productivity and image quality, since it is easy to adjust the drying strength by the air volume and temperature, and it is possible to heat the printing surface quickly and uniformly without directly touching the recording medium.

When heating with a hot air drying heater, the surface temperature of the recording medium exposed to the hot air is preferably 50°C or higher and 150°C or lower, and the wind speed at that time is preferably 5 m/s or higher and 20 m/s or lower. If the surface temperature is 50°C or higher, the adhesion of the resin contained in the treatment liquid will progress, which may improve abrasion resistance, and if the surface temperature is 150°C or lower, the drying speed will be gentle and the glossiness will improve. Furthermore, a wind speed of 5 m/s or higher is preferable because it improves productivity, and a wind speed of 20 m/s or lower is preferable because it improves glossiness.

<Image Formation>
The image-formed product has an image formed on a recording medium using the ink used in the present invention.
An image formed product can be obtained by forming an image using the image forming apparatus and image forming method of the present invention.

<Image forming apparatus and image forming method>
The ink of the present invention can be suitably used in various recording devices using the ink jet recording method, such as printers, facsimile machines, copying machines, printer/fax/copier combination machines, and three-dimensional modeling devices.
In the present invention, the image forming apparatus and image forming method refer to an apparatus capable of ejecting ink, various treatment liquids, etc. onto a recording medium, and a method of recording using the apparatus. The recording medium refers to an object onto which ink or various treatment liquids can be attached even temporarily.
This image forming apparatus can include not only a head portion that ejects ink, but also means related to feeding, conveying, and discharging a recording medium, and other devices called pre-processing devices and post-processing devices.
The image forming apparatus and the image forming method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, a means for heating and drying the printed surface and the back surface of the recording medium. The heating means and the drying means are not particularly limited, but for example, a hot air heater or an infrared heater can be used. Heating and drying can be performed before, during, or after printing.
Furthermore, the image forming apparatus and the image forming method are not limited to those that visualize meaningful images such as characters and figures with ink. For example, those that form patterns such as geometric designs and those that form three-dimensional images are also included.
Furthermore, unless otherwise specified, the image forming apparatus includes both a serial type apparatus in which the ejection head is moved and a line type apparatus in which the ejection head is not moved.
Furthermore, this image forming device includes not only desktop types, but also wide-width image forming devices capable of printing on A0-sized recording media, and continuous-feed printers that can use, for example, continuous paper wound into a roll as a recording medium.

Here, FIG. 1 shows an example of an image forming apparatus for carrying out the image forming method of the present invention, but does not limit the configuration of the apparatus.
The image forming method of the present invention includes four steps, namely, a treatment liquid applying step, an ink applying step, an active energy ray irradiating step, and a drying step, and these four steps are carried out in the above-mentioned order.

First, the recording medium 5 is transported from a paper feed section (not shown) to a treatment liquid application process by a conveyor belt 6, and a treatment liquid containing a nonionic resin, a polyvalent metal salt, and water is applied to a part or the entirety of the recording medium 5 by an application roller 1 as a treatment liquid application means.
Next, ink is discharged from the inkjet head 2 as ink application means onto the recording medium 5 conveyed to the ink application step in accordance with an image pattern, thereby forming an image.
Next, the image is irradiated with active energy rays by an active energy ray irradiation device 3 as an active energy ray irradiation means to cure the ink. By irradiating the image with active energy rays immediately after applying the ink in addition to applying the treatment liquid, beading can be prevented even during high-speed printing, and an image with high abrasion resistance can be formed.
Next, after the active energy ray irradiation step, a drying step is performed. The liquid components contained in the ink and treatment liquid are dried by a hot air heater 4 as drying means. By drying the ink and treatment liquid in the drying step, a film is formed in which the ink and treatment liquid are in close contact with each other, and an image with excellent abrasion resistance can be provided.

The application of the ink used in the present invention is not particularly limited and can be appropriately selected depending on the purpose, and can be applied to, for example, printed matter, paint, coating material, undercoat, etc. Furthermore, the ink can be used not only to form two-dimensional characters and images using the ink, but also as a material for three-dimensional modeling for forming three-dimensional images (three-dimensional models).
A known three-dimensional modeling device for forming a three-dimensional object can be used, and is not particularly limited. For example, a device equipped with an ink storage means, supply means, discharge means, drying means, etc. can be used. The three-dimensional object includes a three-dimensional object obtained by applying ink over and over. Also included is a molded product obtained by processing a structure to which ink is applied on a substrate such as a recording medium. The molded product is, for example, a recorded material or structure formed in a sheet or film shape, which is molded by heat stretching, punching, etc., and is preferably used for applications in which the surface is molded after decoration, such as meters and operation panel of automobiles, office automation equipment, electric and electronic equipment, cameras, etc.

In the present invention, the terms image formation, recording, printing, printing, etc. are all synonymous.
Recording medium, media, and printed material are all synonymous.

The following describes examples of the present invention, but the present invention is not limited to these examples.

(Preparation Example 1 of Resin Particle Dispersion)
--Preparation of Resin Particle Dispersion 1--
In a 1 L flask (A) equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, and a reflux condenser, 89.0 parts by mass of ion-exchanged water was charged, and the temperature was raised to 70° C. while introducing nitrogen. Next, 3.0 parts by mass of a 10% by mass aqueous solution of Aqualon HS-10 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and 2.6 parts by mass of a 5% by mass aqueous solution of ammonium persulfate were added to the flask (A) and stirred.

In a flask (B) separate from the above, 38.9 parts by mass of methyl methacrylate, 49.6 parts by mass of 2-ethylhexyl acrylate, 4.0 parts by mass of methoxypolyethylene glycol monomethacrylate having the structural unit represented by the above general formula (1) (n=23, Blenmer PME-1000, manufactured by NOF Corporation), 7.5 parts by mass of vinyltriethoxysilane, 1.5 parts by mass of Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 42.9 parts by mass of ion-exchanged water were stirred and mixed in a homomixer to obtain an emulsion.

The emulsion in flask (B) was continuously dripped into flask (A) in small amounts over a period of 2.5 hours. In addition, 1.6 parts by mass of a 5% by mass aqueous solution of ammonium persulfate was added every hour for 3 hours from the start of dripping. After dripping was completed, the mixture was aged at 70°C for 2 hours and then cooled to 25°C. The pH was adjusted to 7-8 with 28% by mass aqueous ammonia to obtain resin particle dispersion 1.

The glass transition temperature of the resin particles was measured using a DSC (Q-2000, manufactured by TA Instruments). The specific measurement method was as follows: the resin particle dispersion was heated and dried in an oven at 70°C for 12 hours or more, 5 mg of solids were placed in an aluminum sample container and set in the device, cooled to -70°C under a nitrogen stream and held for 5 minutes, heated to 160°C at 10°C/min, cooled to -70°C and held for 5 minutes, heated to 160°C at 10°C/min, and the DSC curve at the second heating step was selected, and the glass transition temperature was determined by the midpoint method.

The glass transition temperature of the resulting resin particles was measured and found to be -16°C. The results are shown in Table 1-1.

(Resin Particle Dispersion Preparation Examples 2 to 12)
--Preparation of Resin Particle Dispersions 2 to 12--
Resin particle dispersions 2 to 12 were obtained in the same manner as in Resin Particle Dispersion Preparation Example 1, except that the compositions of the flask (A) and the flask (B) in the Resin Particle Dispersion Preparation Example 1 were changed to the types and contents shown in Tables 1-1 and 1-2.
Next, the glass transition temperatures of the resulting resin particles 2 to 12 were measured in the same manner as for the resin particles of Preparation Example 1. The results are shown in Tables 1-1 and 1-2.

Details of each component in Tables 1-1 and 1-2 are as follows.
-Compound having a structural unit represented by the above general formula (1)-
*Methoxypolyethylene glycol monomethacrylate having a structural unit represented by the above general formula (1) (n=2, Blemmer (registered trademark) PME-100, manufactured by NOF Corporation)
*Methoxypolyethylene glycol monomethacrylate having a structural unit represented by the above general formula (1) (n=9, Blemmer (registered trademark) PME-400, manufactured by NOF Corporation)
*Methoxypolyethylene glycol monomethacrylate having a structural unit represented by the above general formula (1) (n=23, Blemmer (registered trademark) PME-1000, manufactured by NOF Corporation)
*Methoxypolyethylene glycol monomethacrylate having a structural unit represented by the above general formula (1) (n=90, Blemmer (registered trademark) PME-4000, manufactured by NOF Corporation)
*Methoxypolyethylene glycol monomethacrylate (n=200, synthetic product) having a structural unit represented by the above general formula (1)

* Polypropylene glycol monomethacrylate (equivalent to n=13, Blenmar (registered trademark) PP-800, manufactured by NOF Corporation)

-Polymerizable monomer-
*Methyl methacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*2-Ethylhexyl acrylate (manufactured by Toagosei Co., Ltd.)
*Styrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

* Vinyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd.)

(Processing solution manufacturing example 1)
--Production of treatment liquid 1--
15 parts by mass of propylene glycol, 5 parts by mass of 3-methoxy-3-methyl-1-butanol, 1 part by mass of TEGO (registered trademark) Wet 270 (manufactured by Evonik Industries), 0.05 parts by mass of Proxel LV (manufactured by Avecia), 0.05 parts by mass of 1,2,3-benzotriazole, 5 parts by mass of magnesium acetate, 10 parts by mass (as solid content) of resin particle dispersion 1, and the remaining amount of pure water so that the total amount was 100 parts by mass were mixed and stirred for 1 hour. The obtained dispersion was pressure-filtered using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to remove coarse particles and dust, thereby preparing treatment liquid 1.

(Processing Solution Production Examples 2 to 21)
--Production of Treatment Solutions 2 to 21--
Treatment solutions 2 to 21 were obtained in the same manner as in Treatment solution Production Example 1, except that the compositions and contents in Treatment solution Production Example 1 were changed to those shown in Tables 2-1 and 2-3.

(Production Example 1 of Pigment Dispersion)
-Production of cyan pigment dispersion-
After the inside of a 1 L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas inlet tube, a reflux condenser, and a dropping funnel was thoroughly replaced with nitrogen gas, 11.2 parts by mass of styrene, 2.8 parts by mass of acrylic acid, 12.0 parts by mass of lauryl methacrylate, 4.0 parts by mass of polyethylene glycol methacrylate, 4.0 parts by mass of styrene macromer, and 0.4 parts by mass of mercaptoethanol were mixed and heated to 65°C.
Next, a mixed solution of 100.8 parts by mass of styrene, 25.2 parts by mass of acrylic acid, 108.0 parts by mass of lauryl methacrylate, 36.0 parts by mass of polyethylene glycol methacrylate, 60.0 parts by mass of hydroxylethyl methacrylate, 36.0 parts by mass of styrene macromer, 3.6 parts by mass of mercaptoethanol, 2.4 parts by mass of azobismethylvaleronitrile, and 18 parts by mass of methyl ethyl ketone was dropped into the flask over 2.5 hours. After dropping, a mixed solution of 0.8 parts by mass of azobismethylvaleronitrile and 18 parts by mass of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 parts by mass of azobismethylvaleronitrile was added and further aged for 1 hour. After the reaction was completed, 364 parts by mass of methyl ethyl ketone was added to the flask to obtain 800 parts by mass of polymer solution A having a concentration of 50% by mass.

Next, 28 parts by mass of the obtained polymer solution A, 26 parts by mass of a phthalocyanine pigment (Chromofine Blue A-220JC, manufactured by Dainichiseika Chemicals Mfg. Co., Ltd.), 13.6 parts by mass of a 1 mol/L potassium hydroxide aqueous solution, 20 parts by mass of methyl ethyl ketone, and 13.6 parts by mass of ion-exchanged water were thoroughly stirred and then kneaded using a roll mill to obtain a paste. The obtained paste was added to 200 parts by mass of pure water and thoroughly stirred, and then the methyl ethyl ketone and water were distilled off using an evaporator. Furthermore, in order to remove coarse particles, this dispersion was pressure-filtered with a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to obtain a pigment-containing polymer microparticle dispersion containing 15% by mass of pigment and 20% by mass of solids.
The average particle diameter (D ₅₀ ) of the polymer fine particles in the obtained pigment dispersion was measured, and the average particle diameter (D ₅₀ ) measured with a particle size distribution measuring device (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.) was 56.0 nm.

(Ink Production Example 1)
-Production of Ink 1-
2.0 parts by mass of propane-1,2-diol, 1.7 parts by mass of 3-methoxy-3-methyl-1-butanol, 5.0 parts by mass of 3-methoxy-N,N-dimethylpropionamide, 1.2 parts by mass of TEGO (registered trademark) Wet 270 (manufactured by EVONIK INDUSTRIES), 0.1 parts by mass of Proxel LV (manufactured by Avecia), 0.1 parts by mass of 1,2,3-benzotriazole, and 68.8 parts by mass of ion-exchanged water were mixed and stirred for 1 hour to make the mixture uniform.
Next, 6.0 parts by mass of 4-hydroxybutyl acrylate (manufactured by Nippon Kasei Kasei Co., Ltd.) was added to the obtained mixed liquid and stirred for 1 hour, and then 3.4 parts by mass (as solid content) of the cyan pigment dispersion, 1.0 part by mass of 2-hydroxy-2-methyl-1-phenylpropanone, and 8.0 parts by mass (as solid content) of reactive urethane dispersion (Laromer LR8983, manufactured by BASF Corporation) were added and stirred for another 1 hour. The obtained dispersion was pressure filtered through a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to remove coarse particles and dust, thereby preparing ink 1.

(Ink Production Example 2)
-Production of Ink 2-
4.5 parts by mass of propane-1,2-diol, 6.2 parts by mass of 3-methoxy-3-methyl-1-butanol, 5.0 parts by mass of 3-methoxy-N,N-dimethylpropionamide, 1.2 parts by mass of TEGO (registered trademark) Wet 270 (manufactured by EVONIK INDUSTRIES), 0.1 parts by mass of Proxel LV (manufactured by Avecia), 0.1 parts by mass of 1,2,3-benzotriazole, and 64.5 parts by mass of ion-exchanged water were mixed and stirred for 1 hour to make a homogenous mixture. 3.4 parts by mass (as solids) of the cyan pigment dispersion and 8.0 parts by mass (as solids) of UX3945 (manufactured by Sanyo Chemical Industries, Ltd.) as a urethane emulsion were added to the mixed liquid and further stirred for 1 hour. The obtained dispersion was pressure-filtered using a polyvinylidene fluoride membrane filter with an average pore size of 5.0 μm to remove coarse particles and dust, and ink 2 was prepared.

Example 1
<Image Formation>
A single-pass printing apparatus was prepared in which the treatment liquid application step, ink application step, active energy ray irradiation step, and drying step could all be carried out in-line, as shown in FIG.
In the treatment liquid application step, the treatment liquid 1 was applied using a roller coater so as to give a coating thickness of 50 μm.
In the ink application process, a piezoelectric on-demand type head was mounted as the recording head, and the ink 1 was used as the printing ink.
The printing conditions were as follows: head gap 2 mm, ejection amount per droplet 4 pL, 1200 dpi, and deposition amount 1.0 μL/cm ² .
Following the ink application process, the ink was cured using an ultraviolet ray irradiation device Subzero085 (using D bulb) manufactured by Integration Technology Co., Ltd., which was mounted on the printing device. The ultraviolet ray irradiation device used two lamps with an illuminance of 3.7 W/ ^cm2 , and irradiation was performed so that the cumulative amount of UV-A light was 352 mJ/ ^cm2 .
Furthermore, the image was dried with hot air using a hot air heater mounted on the printing device, with the hot air temperature at 70° C. and the air speed at 10 m/s. In this manner, the image of Example 1 was obtained.
The printing was carried out under environmental conditions adjusted to 23° C.±0.5° C. and 50% RH±5% RH, and coated cardboard OK-Ball (manufactured by Oji Paper Co., Ltd.) was used as the recording medium.

(Examples 2 to 19 and Comparative Examples 5 to 6)
The images of Examples 2 to 19 and Comparative Examples 5 to 6 were obtained in the same manner as in Example 1, except that the processing liquid 1 in Example 1 was changed to processing liquids 2 to 21.

(Examples 20 to 23)
Images of Examples 20 to 23 were obtained in the same manner as in Example 1, except that the integrated light amount of UV-A in Example 1 was changed to the value shown in Table 4. The integrated light amount of UV-A was adjusted by changing the lamp output of the ultraviolet irradiation device and the speed at which the recording medium passed under the ultraviolet irradiation device.

(Comparative Example 1)
An image of Comparative Example 1 was obtained in the same manner as in Example 1, except that Processing Liquid 1 was not used.

(Comparative Examples 2 to 4)
Images of Comparative Examples 2 to 4 were obtained in the same manner as in Example 1, except that the order of the treatment liquid application step, the ink application step, the active energy ray irradiation step, and the drying step was changed to that shown in Table 3.

(Comparative Example 7)
An image of Comparative Example 7 was obtained in the same manner as in Example 1, except that "Ink 1" in Example 1 was changed to "Ink 2."

Next, the images obtained were evaluated for "beading," "abrasion resistance," and "gloss" as follows. The results are shown in Table 4.

<Evaluation of beading (uneven density)>
Using the above single-pass printing device, a solid image of 5 cm x 20 cm was printed, and the degree of density unevenness (beading) caused by the gathering of dots was evaluated by visual inspection. The beading evaluation was best at A, and the acceptable range was C or higher.
[Evaluation criteria]
A: No unevenness in density is observed. B: Slight unevenness in density is observed, but not problematic. C: Some unevenness in density is observed. D: Severe unevenness in density is observed.

<Evaluation of Scratch Resistance>
Using the above single pass printing device, a solid image of 5 cm x 20 cm was prepared, and then the prepared cured product and a test attachment white cloth (Kanakin No. 3) conforming to JIS L 0803 were attached to a friction fastness tester RT-300 (manufactured by Daiei Scientific Instruments Manufacturing Co., Ltd.) (an apparatus conforming to the friction tester type II (Gakushin type) specified in the dye fastness test method (JIS L-0849)), and a weight of 500 g was attached, and the cured product was rubbed back and forth 100 times. The density of the cotton cloth after the test was measured with eXact Scan (manufactured by X-Rite Co., Ltd.), and the density difference with a cotton cloth that was not tested was evaluated. The measurement results were evaluated based on the following evaluation criteria. The best child evaluation was A, and the acceptable range was C or higher.
[Evaluation criteria]
A: 0.02 or less B: More than 0.02 and 0.1 or less C: More than 0.1 and 0.2 or less D: More than 0.2

<Evaluation of Gloss>
A solid image of 5 cm x 20 cm was prepared using the above single pass printing device. The glossiness of the image was evaluated visually based on the following evaluation criteria. The best evaluation was A, and the acceptable range was C or higher.
[Evaluation criteria]
A: Very high glossiness B: High glossiness (slightly glossier than the background of the recording medium)
C: Slightly glossy (same gloss level as the background of the recording medium)
D: No gloss (lower gloss than the background of the recording medium)

ただし、前記一般式（１）中、Ｒ_１は－ＣＯＯ－を表し、Ｒ_２及びＲ_３は水素原子又は炭素数１以上４以下のアルキル基を表し、ｎは５以上１００以下の整数である。
＜３＞ 前記一般式（１）において、ｎが１０以上５０以下の整数である、前記＜２＞に記載の画像形成方法である。
＜４＞ 前記樹脂は、モノマー由来のモノマー単位と架橋剤由来の架橋単位とを含み、前記樹脂における前記モノマー由来のモノマー単位と前記架橋剤由来の架橋単位との合計を１００質量部としたとき、前記一般式（１）で示される構造単位を１質量部以上２０質量部以下含む、前記＜２＞から＜３＞のいずれかに記載の画像形成方法である。
＜５＞ 前記樹脂のガラス転移温度が－４０℃以上０℃以下である、前記＜１＞から＜４＞のいずれかに記載の画像形成方法である。
＜６＞ 前記多価金属塩の含有量が０．１質量％以上２０質量％以下である、前記＜１＞から＜５＞のいずれかに記載の画像形成方法である。
＜７＞ 前記多価金属塩における多価金属が、カルシウム、マグネシウム、及びアルミニウムから選択される少なくとも１種である、前記＜１＞から＜６＞のいずれかに記載の画像形成方法である。
＜８＞ 前記インクが重合開始剤を含有する、前記＜１＞から＜７＞のいずれかに記載の画像形成方法である。
＜９＞ 前記処理液が前記インクの重合開始剤に相当する化合物を含まない、前記＜８＞に記載の画像形成方法である。
＜１０＞ 前記インク付与工程で用いる記録ヘッドがラインヘッド方式であり、前記記録媒体が前記記録ヘッドの下部を通過し、その通過時に前記記録ヘッドから前記インクが付与される、前記＜１＞から＜９＞のいずれかに記載の画像形成方法である。
＜１１＞ 前記活性エネルギー線照射工程における記録媒体表面のＵＶ－Ａの積算光量が１７ｍＪ／ｃｍ^２以上２，０００ｍＪ／ｃｍ^２以下である、前記＜１＞から＜１０＞のいずれかに記載の画像形成方法である。
＜１２＞ 前記乾燥工程における加熱が温風乾燥ヒーターを用いて行われる、前記＜１＞から＜１１＞のいずれかに記載の画像形成方法である。
＜１３＞ 記録媒体上に、樹脂、多価金属塩、及び水を含有する処理液を付与する処理液付与手段と、
前記処理液が付与された記録媒体上に、水、色材、及び重合性化合物を含有するインクを付与し、画像を形成するインク付与手段と、
前記画像に活性エネルギー線を照射する活性エネルギー線照射手段と、
照射後の画像を加熱し乾燥させる乾燥手段と、
を有することを特徴とする画像形成装置である。
＜１４＞ ノニオン性樹脂、多価金属塩、及び水を含有することを特徴とする処理液である。
＜１５＞ 前記ノニオン性樹脂は、下記一般式（１）で表される構造単位を含む、前記＜１４＞に記載の処理液である。

ただし、前記一般式（１）中、Ｒ_１は－ＣＯＯ－を表し、Ｒ_２及びＲ_３は水素原子又は炭素数１以上４以下のアルキル基を表し、ｎは５以上１００以下の整数である。
＜１６＞ 前記一般式（１）において、ｎが１０以上５０以下の整数である、前記＜１５＞に記載の処理液である。
＜１７＞ 前記ノニオン性樹脂はモノマー由来のモノマー単位と架橋剤由来の架橋単位とを含み、前記ノニオン性樹脂における前記モノマー由来のモノマー単位と前記架橋剤由来の架橋単位との合計を１００質量部としたとき、前記一般式（１）で示される構造単位を１質量部以上２０質量部以下含む、前記＜１４＞から＜１６＞のいずれかに記載の処理液である。
＜１８＞ 前記ノニオン性樹脂のガラス転移温度が－４０℃以上０℃以下である、前記＜１４＞から＜１７＞のいずれかに記載の処理液である。
＜１９＞ 前記多価金属塩の含有量が０．１質量％以上２０質量％以下である、前記＜１４＞から＜１８＞のいずれかに記載の処理液である。
＜２０＞ 前記多価金属塩における多価金属が、カルシウム、マグネシウム、及びアルミニウムから選択される少なくとも１種である、前記＜１４＞から＜１９＞のいずれかに記載の処理液である。
＜２１＞ 前記＜１４＞から＜２０＞のいずれかに記載の処理液と、
水、色材、重合開始剤、及び重合性化合物を含有するインクと、
を有することを特徴とする処理液とインクのセットである。
＜２２＞ 前記処理液が前記インクの重合開始剤に相当する化合物を含まない、前記＜２１＞に記載の処理液とインクのセットである。 For example, aspects of the present invention are as follows.
<1> A treatment liquid application step of applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium;
an ink applying step of applying an ink containing water, a coloring material, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image;
an active energy ray irradiation step of irradiating the image with active energy rays;
a drying step of heating and drying the irradiated image;
The image forming method is characterized by comprising:
<2> The image forming method according to <1> above, wherein the resin is a nonionic resin and contains a structural unit represented by the following general formula (1):

In the general formula (1), R ₁ represents —COO—, R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 5 to 100.
<3> The image forming method according to <2> above, wherein in formula (1), n is an integer of 10 or more and 50 or less.
<4> The image forming method according to any one of <2> to <3>, wherein the resin contains a monomer unit derived from a monomer and a crosslinking unit derived from a crosslinking agent, and contains a structural unit represented by General Formula (1) in an amount of 1 part by mass to 20 parts by mass when a total of the monomer units derived from the monomer and the crosslinking units derived from the crosslinking agent in the resin is taken as 100 parts by mass.
<5> The image forming method according to any one of <1> to <4>, wherein the resin has a glass transition temperature of −40° C. or higher and 0° C. or lower.
<6> The image forming method according to any one of <1> to <5>, wherein the content of the polyvalent metal salt is 0.1% by mass or more and 20% by mass or less.
<7> The image forming method according to any one of <1> to <6>, wherein the polyvalent metal in the polyvalent metal salt is at least one selected from the group consisting of calcium, magnesium, and aluminum.
<8> The image forming method according to any one of <1> to <7>, wherein the ink contains a polymerization initiator.
<9> The image forming method according to <8>, wherein the treatment liquid does not contain a compound corresponding to a polymerization initiator of the ink.
<10> The image forming method according to any one of <1> to <9>, wherein a recording head used in the ink applying step is a line head type, the recording medium passes under the recording head, and the ink is applied from the recording head during the passing of the recording medium.
<11> The image forming method according to any one of <1> to <10>, wherein an integrated amount of UV-A on the recording medium surface in the active energy ray irradiation step is 17 mJ/cm ² or more and 2,000 mJ/cm ² or less.
<12> The image forming method according to any one of <1> to <11>, wherein the heating in the drying step is performed using a hot air drying heater.
<13> A treatment liquid applying unit that applies a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium;
an ink applying unit that applies an ink containing water, a coloring material, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image;
an active energy ray irradiation means for irradiating the image with active energy rays;
A drying means for heating and drying the image after irradiation;
The image forming apparatus is characterized by having the following features.
<14> A treatment liquid comprising a nonionic resin, a polyvalent metal salt, and water.
<15> The treatment liquid according to <14>, wherein the nonionic resin contains a structural unit represented by the following general formula (1):

In the general formula (1), R ₁ represents —COO—, R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 5 to 100.
<16> The treatment liquid according to <15>, wherein in formula (1), n is an integer of 10 or more and 50 or less.
<17> The treatment liquid according to any one of <14> to <16>, wherein the nonionic resin contains a monomer unit derived from a monomer and a crosslinking unit derived from a crosslinking agent, and when the total of the monomer units derived from the monomer and the crosslinking units derived from the crosslinking agent in the nonionic resin is taken as 100 parts by mass, the treatment liquid contains a structural unit represented by general formula (1) in an amount of 1 part by mass to 20 parts by mass.
<18> The treatment liquid according to any one of <14> to <17>, wherein the nonionic resin has a glass transition temperature of −40° C. or higher and 0° C. or lower.
<19> The treatment liquid according to any one of <14> to <18>, wherein the content of the polyvalent metal salt is 0.1% by mass or more and 20% by mass or less.
<20> The treatment liquid according to any one of <14> to <19>, wherein the polyvalent metal in the polyvalent metal salt is at least one selected from the group consisting of calcium, magnesium, and aluminum.
<21> The treatment liquid according to any one of <14> to <20>,
an ink containing water, a coloring material, a polymerization initiator, and a polymerizable compound;
The set of treatment liquid and ink is characterized by having
<22> The set of treatment liquid and ink according to <21>, wherein the treatment liquid does not contain a compound corresponding to a polymerization initiator of the ink.

The image forming method described in any one of <1> to <12>, the image forming apparatus described in <13>, the treatment liquid described in any one of <14> to <20>, and the set of treatment liquid and ink described in any one of <21> to <22> can solve the problems of the prior art and achieve the object of the present invention.

REFERENCE SIGNS LIST 1 Treatment liquid applying means 2 Ink applying means 3 Active energy ray irradiating means 4 Drying means 5 Recording medium 6 Conveyor belt

Japanese Patent No. 6019236

Claims (15)

a treatment liquid application step of applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium;
an ink applying step of applying an ink containing water, a coloring material, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image;
an active energy ray irradiation step of irradiating the image with active energy rays;
a drying step of heating and drying the irradiated image;
An image forming method comprising the steps of: 2. The image forming method according to claim 1, wherein the resin is a nonionic resin and contains a structural unit represented by the following general formula (1):

In the general formula (1), R ₁ represents —COO—, R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 5 to 100. The image forming method according to claim 2, wherein in the general formula (1), n is an integer of 10 or more and 50 or less. The image forming method according to any one of claims 2 to 3, wherein the resin contains a monomer unit derived from a monomer and a crosslinking unit derived from a crosslinking agent, and contains 1 part by mass or more and 20 parts by mass or less of the structural unit represented by the general formula (1) when the total of the monomer units derived from the monomer and the crosslinking units derived from the crosslinking agent in the resin is taken as 100 parts by mass. The image forming method according to any one of claims 1 to 4, wherein the glass transition temperature of the resin is -40°C or higher and 0°C or lower. The image forming method according to any one of claims 1 to 5, wherein the content of the polyvalent metal salt is 0.1% by mass or more and 20% by mass or less. The image forming method according to any one of claims 1 to 6, wherein the polyvalent metal in the polyvalent metal salt is at least one selected from calcium, magnesium, and aluminum. The image forming method according to any one of claims 1 to 7, wherein the ink contains a polymerization initiator. The image forming method according to claim 8, wherein the treatment liquid does not contain a compound equivalent to a polymerization initiator of the ink. The image forming method according to any one of claims 1 to 9, wherein the recording head used in the ink application process is a line head type, the recording medium passes under the recording head, and the ink is applied from the recording head during the passage. 11. The image forming method according to claim 1, wherein an integrated amount of UV-A on the surface of the recording medium in the active energy ray irradiation step is 17 mJ/cm ² or more and 2,000 mJ/cm ² or less. The image forming method according to any one of claims 1 to 11, wherein the heating in the drying step is performed using a hot air drying heater. a treatment liquid applying means for applying a treatment liquid containing a resin, a polyvalent metal salt, and water onto a recording medium;
an ink applying unit that applies an ink containing water, a coloring material, and a polymerizable compound onto the recording medium to which the treatment liquid has been applied, thereby forming an image;
an active energy ray irradiation means for irradiating the image with active energy rays;
A drying means for heating and drying the image after irradiation;
An image forming apparatus comprising: A treatment liquid containing a nonionic resin, a polyvalent metal salt, and water;
an ink containing water, a coloring material, a polymerization initiator, and a polymerizable compound;
A set of a treatment liquid and an ink, comprising: The set of treatment liquid and ink according to claim 14 , wherein the treatment liquid does not contain a compound corresponding to a polymerization initiator of the ink.