Active energy ray-curable inkjet ink, active energy ray-curable ink set, and image recording method

Abstract

The invention discloses an active energy ray-curable inkjet ink, an active energy ray-curable ink set, and an image recording method. The active energy ray-curable inkjet ink contains a bifunctional (meth) acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms, a silicone-based surfactant having a (meth) acryloyl group, a colorant, and an acrylic resin having a glass transition temperature of 30 DEG C or higher, the content of the bifunctional (meth) acrylate is 20% by mass or more with respect to the total amount of the active energy ray-curable inkjet ink.

Description

Technical Field

[0001] The present disclosure relates to an active energy ray-curable inkjet ink, an active energy ray-curable ink set, and an image recording method. Background Art

[0002] Conventionally, there is known a method of curing the ink using active energy rays when recording an image on a substrate using ink.

[0003] For example, Japanese Patent Application Laid-Open No. 2018-035369 describes an inkjet ink composition for printing on building materials, characterized in that it contains: a radical polymerizable compound as component A; a radical polymerization initiator as component B; a coloring pigment as component C; and a pigment dispersant as component D, wherein component A contains: benzyl (meth)acrylate and / or 2-phenoxyethyl (meth)acrylate as component A-1; a monofunctional or difunctional (meth)acrylate compound having an aliphatic hydrocarbon group with 6 or more carbon atoms as component A-2; and a pigment dispersant as component D. The ink composition further comprises at least one component A-3 selected from the group consisting of compounds represented by any one of the following formulae II and III, the total content of component A-1 is 10% to 50% by mass relative to the total mass of the ink composition, the total content of component A-2 is 5% to 40% by mass relative to the total mass of the ink composition, and the total content of component A-3 is 10% to 50% by mass relative to the total mass of the ink composition, and the ink composition further comprises at least one inorganic pigment selected from the group consisting of Pigment Blue 28, Pigment Red 101, Pigment Yellow 42, and Pigment Yellow 184 as component C. Summary of the Invention

[0004] Technical issues to be solved by the invention

[0005] Image records obtained by applying ink to a substrate are sometimes required to have excellent scratch resistance and releasability of the image from the substrate.

[0006] The present disclosure is made in view of this situation, and the problem to be solved by one embodiment of the present invention is to provide an active energy ray-curable inkjet ink, an active energy ray-curable ink set and an image recording method that can obtain an image recording material with excellent abrasion resistance and separation properties of the image from the substrate.

[0007] Means for solving technical problems

[0008] The present disclosure includes the following aspects.

[0009] <1> An active energy ray-curable inkjet ink comprising a bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms, a silicone surfactant having a (meth)acryloyl group, a colorant, and an acrylic resin having a glass transition temperature of 30°C or higher, wherein the content of the bifunctional (meth)acrylate is 20% by mass or higher relative to the total amount of the active energy ray-curable inkjet ink.

[0010] <2> The active energy ray-curable inkjet ink according to <1>, wherein a mass ratio of the content of the silicone-based surfactant having a (meth)acryloyl group to the content of the acrylic resin is 1 to 10.

[0011] <3> The active energy ray-curable inkjet ink according to <1> or <2>, wherein the mass ratio of the content of the silicone-based surfactant having a (meth)acryloyl group to the content of the acrylic resin is 4 to 7.

[0012] <4> The active energy ray-curable inkjet ink according to any one of <1> to <3>, wherein the content of the silicone surfactant having a (meth)acryloyl group is 0.5% by mass to 10% by mass based on the total amount of the active energy ray-curable inkjet ink.

[0013] <5> The active energy ray-curable inkjet ink according to any one of <1> to <4>, wherein the content of the silicone surfactant having a (meth)acryloyl group is 4% to 7% by mass based on the total amount of the active energy ray-curable inkjet ink.

[0014] <6> The active energy ray-curable inkjet ink according to any one of <1> to <5>, wherein the silicone surfactant having a (meth)acryloyl group contains a polyether structure and a polysiloxane structure, and the mass ratio of the content of the polysiloxane structure to the content of the polyether structure is 0.5 or more.

[0015] <7> The active energy ray-curable inkjet ink according to any one of <1> to <6>, further comprising a monofunctional (meth)acrylate having a hydroxyl group.

[0016] <8> The active energy ray-curable inkjet ink according to any one of <1> to <7>, wherein the acrylic resin has a weight average molecular weight of 5,000 to 100,000.

[0017] <9> An active energy ray-curable ink set comprising: a first ink, wherein the first ink is the active energy ray-curable inkjet ink described in any one of <1> to <8>, and the colorant is a pigment other than a white pigment; and a second ink, wherein the second ink is the active energy ray-curable inkjet ink described in any one of <1> to <8>, and the colorant is a white pigment.

[0018] <10> The active energy ray-curable ink set according to <9>, wherein, when the first ink and the second ink are equal in mass, the acrylic resin content in the first ink is greater than the acrylic resin content in the second ink.

[0019] <11> The active energy ray-curable ink set according to <9> or <10>, further comprising a third ink containing at least one acid group-containing compound selected from the group consisting of a polymerizable monomer having an acid group and a polymer having an acid group.

[0020] <12> The active energy ray-curable ink set according to <11>, wherein, when the first ink, the second ink, and the third ink are of the same mass, the content of the acrylic resin in the first ink is greater than the content of the acrylic resin in the second ink, and the content of the acrylic resin in the first ink is greater than the content of the acrylic resin in the third ink.

[0021] <13> An image recording method comprising: applying the active energy ray-curable inkjet ink according to any one of <1> to <8> to a substrate by inkjet recording; and irradiating the applied active energy ray-curable inkjet ink with active energy rays.

[0022] <14> An image recording method using the active energy ray-curable ink set described in any one of <9> to <12>, comprising the steps of: imparting a second ink to a substrate by inkjet recording; irradiating the imparted second ink with active energy rays; imparting a first ink to the substrate imparted with the second ink by inkjet recording; and irradiating the imparted first ink with active energy rays.

[0023] Effects of the Invention

[0024] According to one embodiment of the present invention, an active energy ray-curable inkjet ink, an active energy ray-curable ink set, and an image recording method are provided that can produce an image recorded product having excellent abrasion resistance and image separation properties from a substrate. DETAILED DESCRIPTION

[0025] Hereinafter, the active energy ray-curable inkjet ink, the active energy ray-curable ink set, and the image recording method of the present disclosure will be described in detail.

[0026] In this specification, the numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0027] In the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced by the upper limit or lower limit of another numerical range described in another stage. In addition, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced by the value shown in the Examples.

[0028] In this specification, when there are multiple substances corresponding to each component in the composition, the amount of each component in the composition refers to the total amount of the multiple substances present in the composition unless otherwise specified.

[0029] In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0030] In this specification, the term "process" refers not only to an independent process but also to a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0031] In this specification, "image" means the entire film formed by applying ink, and "image recording" means the formation of an image (ie, film).

[0032] In addition, the concept of "image" in this specification also includes solid images.

[0033] In this specification, "(meth)acrylate" is a concept encompassing both acrylate and methacrylate. Also, "(meth)acryl" is a concept encompassing both acryl and methacryl.

[0034] An active energy ray-curable inkjet ink (hereinafter also referred to as "ink") as one embodiment of the present disclosure contains a difunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms, a silicone surfactant having a (meth)acryloyl group, a colorant, and an acrylic resin having a glass transition temperature of 30°C or above. The content of the difunctional (meth)acrylate is 20% by mass or more relative to the total amount of the active energy ray-curable inkjet ink.

[0035] For example, by applying the ink of one embodiment of the present disclosure to a substrate and then irradiating the substrate with active energy rays, an image recorded material having an ink film as an image formed on the substrate can be obtained. Since the ink of one embodiment of the present disclosure contains a bifunctional (meth)acrylate having a linear or branched alkylene group with 4 to 10 carbon atoms and a silicone surfactant having a (meth)acryloyl group, irradiation with active energy rays causes a polymerization reaction to proceed. In particular, since the ink contains a silicone surfactant having a (meth)acryloyl group, it is believed that the ink film formed by the polymerization reaction has surface activity. For example, when the image recorded material is immersed in a treatment liquid (e.g., an alkaline aqueous solution), the adhesion between the substrate and the ink film decreases, and the ink film peels off from the substrate. Since the ink film formed by the ink of one embodiment of the present disclosure has surface activity, it easily floats after being peeled off from the substrate and has excellent separability. Therefore, when the substrate is reused, for example, the substrate after the image is separated can be recovered.

[0036] Furthermore, since the ink according to one embodiment of the present disclosure contains an acrylic resin having a glass transition temperature of 30° C. or higher, it is considered that the surface hardness of the ink film is increased and the scratch resistance is excellent.

[0037] On the other hand, Japanese Patent Application Laid-Open No. 2018-035369 does not assume that the content of the bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms is set to 20% by mass or more relative to the total amount of the ink.

[0038] Hereinafter, each component contained in the ink which is one embodiment of the present disclosure will be described.

[0039] [Active energy ray curable inkjet ink]

[0040] The ink of one embodiment of the present disclosure is an active energy ray-curable ink. That is, the ink of one embodiment of the present disclosure is cured by exposure to active energy rays. Examples of active energy rays include gamma rays, beta rays, electron beams, ultraviolet rays, and visible light. Ultraviolet rays are preferred. The ink of one embodiment of the present disclosure is preferably a UV-curable ink.

[0041] <Bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms>

[0042] The ink according to one embodiment of the present disclosure contains a bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms (hereinafter also referred to as a “specific bifunctional (meth)acrylate”).

[0043] The difunctional (meth)acrylate refers to a compound having two (meth)acryloyloxy groups.

[0044] The specific bifunctional (meth)acrylate has a linear or branched alkylene group having 4 to 10 carbon atoms, and the resulting image has excellent scratch resistance.

[0045] Examples of the linear or branched alkylene group include methylene, ethylene, isopropylidene, n-butylene, tert-butylene, and heptyl. From the same viewpoint as above, the linear or branched alkylene group preferably has 6 to 8 carbon atoms, more preferably 6.

[0046] The specific bifunctional (meth)acrylate contained in the ink may be one kind or two or more kinds.

[0047] Examples of the specific bifunctional (meth)acrylate include 3-methyl-1,5-pentanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol diacrylate, 1,7-heptanediol diacrylate, 1,8-octanediol diacrylate, and 1,9-nonanediol di(meth)acrylate.

[0048] Among them, from the viewpoint of ejectability, the specific bifunctional (meth)acrylate is preferably at least one selected from the group consisting of 3-methyl-1,5-pentanediol di(meth)acrylate and 1,6-hexanediol diacrylate, and more preferably 3-methyl-1,5-pentanediol di(meth)acrylate.

[0049] From the viewpoint of scratch resistance and odor, the content of the specific bifunctional (meth)acrylate is 20% by mass or more, preferably 20% by mass to 80% by mass, and more preferably 30% by mass to 50% by mass, relative to the total amount of the ink.

[0050] <Monofunctional (meth)acrylate having a hydroxyl group>

[0051] The ink according to one embodiment of the present disclosure preferably contains a monofunctional (meth)acrylate having a hydroxyl group (hereinafter also referred to as a “specific monofunctional (meth)acrylate”).

[0052] The monofunctional (meth)acrylate refers to a compound having one (meth)acryloyloxy group.

[0053] The specific monofunctional (meth)acrylate, due to its hydroxyl group, inhibits localized water accumulation in the ink film and improves water resistance. Furthermore, the presence of the specific monofunctional (meth)acrylate reduces the oxygen concentration in the ink, suppressing polymerization inhibition caused by oxygen and improving curability. As a result, unreacted polymerizable compounds can be reduced, reducing odor.

[0054] The specific monofunctional (meth)acrylate contained in the ink may be only one kind or two or more kinds.

[0055] The number of hydroxyl groups contained in the specific monofunctional (meth)acrylate is not particularly limited, and is, for example, 1 to 6. From the viewpoint of ink viscosity, the number of hydroxyl groups is preferably 1 to 3, and more preferably 1 or 2.

[0056] The molecular weight of the specific monofunctional (meth)acrylate is preferably 130 to 150 from the viewpoint of low odor and low viscosity.

[0057] Examples of the specific monofunctional (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, 4-hydroxybutyl (meth)acrylate is preferred from the perspectives of water resistance and low odor.

[0058] From the viewpoint of water resistance and low odor, the content of the specific monofunctional (meth)acrylate is preferably 30% by mass to 70% by mass, more preferably 40% by mass to 50% by mass, based on the total amount of the ink.

[0059] <Other polymerizable compounds>

[0060] The ink according to one embodiment of the present disclosure may contain other polymerizable compounds in addition to the specific bifunctional (meth)acrylate and the specific monofunctional (meth)acrylate, within a range not significantly impairing the effects of the present disclosure.

[0061] The other polymerizable compounds are not particularly limited as long as they are compounds other than the specific bifunctional (meth)acrylate and the specific monofunctional (meth)acrylate and have a polymerizable group.

[0062] From the perspective of reactivity with the specific bifunctional (meth)acrylate, the polymerizable group in the other polymerizable compound is preferably a radical polymerizable group, more preferably an ethylenically unsaturated group, and even more preferably a (meth)acryloyloxy group. That is, the other polymerizable compound is preferably a radical polymerizable compound, more preferably an ethylenically unsaturated compound, and even more preferably a (meth)acrylate compound.

[0063] The other polymerizable compound may be a monofunctional polymerizable compound having one polymerizable group, or may be a polyfunctional polymerizable compound having two or more polymerizable groups.

[0064] —Monofunctional polymerizable compound—

[0065] Examples of the monofunctional polymerizable compound include monofunctional (meth)acrylates, monofunctional (meth)acrylamides, monofunctional aromatic vinyl compounds, monofunctional vinyl ethers, and monofunctional N-vinyl compounds.

[0066] Examples of the monofunctional (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tert-octyl (meth)acrylate, isoamyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, 2- Ethylhexyldiethylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 4-bromobutyl (meth)acrylate, cyanoethyl (meth)acrylate, benzyl (meth)acrylate, butoxymethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, 2-(2-butoxyethoxy)ethyl (meth)acrylate, 2,2,2-tetrafluoroethyl (meth)acrylate, 1H,1H,2H,2H-perfluorodecyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl ester, 4-chlorophenyl (meth)acrylate, 2-phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, glycidyl (meth)acrylate, glycidyloxybutyl (meth)acrylate, glycidyloxyethyl (meth)acrylate, glycidyloxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, phenyl glycidyl ether (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, trimethylsilylpropyl (meth)acrylate, polyethylene oxide monomethyl ether (meth)acrylate, polyethylene oxide (meth)acrylate, polyethylene oxide monoalkyl ether (meth)acrylate, dipropylene glycol (meth)acrylate, Polypropylene oxide monoalkyl ether (meth)acrylate, 2-methacryloyloxyethylsuccinic acid, 2-methacryloyloxyhexahydrophthalic acid, ethoxydiethylene glycol (meth)acrylate, butoxydiethylene glycol (meth)acrylate, trifluoroethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, ethylene oxide (EO)-modified phenol (meth)acrylate, EO-modified cresol (meth)acrylate, EO-modified nonylphenol (meth)acrylate , propylene oxide (PO) modified nonylphenol (meth) acrylate, EO modified 2-ethylhexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentyl (meth) acrylate, (3-ethyl-3-oxetanylmethyl) (meth) acrylate, phenoxyethylene glycol (meth) acrylate, 2-carboxyethyl (meth) acrylate and 2-(meth)acryloyloxyethyl succinate.

[0067] Examples of the monofunctional (meth)acrylamide include (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-n-butyl (meth)acrylamide, N-tert-butyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-methylol (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, and (meth)acryloylmorpholine.

[0068] Examples of the monofunctional aromatic vinyl compound include styrene, dimethylstyrene, trimethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, methyl vinylbenzoate, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene, 3-octylstyrene, 4-octylstyrene, 3-(2-ethylhexyl)styrene, 4-(2-ethylhexyl)styrene, allylstyrene, isopropenylstyrene, butenylstyrene, octenylstyrene, 4-tert-butoxycarbonylstyrene, and 4-tert-butoxystyrene.

[0069] Examples of the monofunctional vinyl ether include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenyloxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, and phenoxypolyethylene glycol vinyl ether.

[0070] Examples of the monofunctional N-vinyl compound include N-vinyl-ε-caprolactam and N-vinylpyrrolidone.

[0071] —Multifunctional polymerizable compound—

[0072] Examples of the polyfunctional polymerizable compound include polyfunctional (meth)acrylate compounds and polyfunctional vinyl ethers.

[0073] Examples of the polyfunctional (meth)acrylate include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, EO-modified neopentyl glycol di(meth)acrylate, PO-modified neopentyl glycol di(meth)acrylate, EO-modified hexanediol di(meth)acrylate, PO-modified hexanediol di(meth)acrylate, decanediol di(meth)acrylate, dodecanediol di(meth)acrylate, and glycerol di(meth)acrylate.

[0014] The present invention also includes but is not limited to the following: 1,2-dimethylolpropane tri(meth)acrylate, ...

[0074] Examples of the polyfunctional vinyl ether include 1,4-butanediol divinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, and bisphenol F alkylene oxide divinyl ether. ether), trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerol trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether, EO addition trimethylolpropane trivinyl ether, PO addition trimethylolpropane trivinyl ether, EO addition ditrimethylolpropane tetravinyl ether, PO addition ditrimethylolpropane tetravinyl ether, EO addition pentaerythritol tetravinyl ether, PO addition pentaerythritol tetravinyl ether, EO addition dipentaerythritol hexavinyl ether and PO addition dipentaerythritol hexavinyl ether.

[0075] Colorants

[0076] The ink according to one embodiment of the present disclosure contains at least one colorant.

[0077] In the present disclosure, a colorant refers to a substance that, when included in an ink, can make the ink a colored or achromatic ink.

[0078] The colorant may be a chromatic colorant (eg, cyan, magenta, yellow, etc.) or an achromatic colorant (eg, white and black).

[0079] Examples of the colorant include dyes and pigments, and the colorant is preferably a pigment from the viewpoint of durability such as heat resistance, light resistance, and water resistance.

[0080] When using a pigment as a colorant, the pigment can be included in the ink as a pigment dispersion. A pigment dispersion is a liquid obtained by dispersing the pigment in a liquid medium using a dispersant, and contains at least a pigment, a dispersant, and a liquid medium. Details of the dispersant will be described later. The liquid medium can be an organic solvent or a polymerizable compound.

[0081] As pigment, any of commercially available organic pigments and inorganic pigments can be used. As pigment, for example, the pigments described in "Dictionary of Pigments" (2000) compiled by Seishiro Ito, W.Herbst, K.Hunger "Industrial Organic Pigments", Japanese Patent Publication No. 2002-12607, Japanese Patent Publication No. 2002-188025, Japanese Patent Publication No. 2003-26978 and Japanese Patent Publication No. 2003-342503 can be enumerated.

[0082] The content of the colorant is preferably 0.5% by mass to 15% by mass, more preferably 1% by mass to 10% by mass, and even more preferably 2% by mass to 5% by mass, relative to the total amount of the ink.

[0083] Dispersants

[0084] When a pigment is used as a colorant, the pigment can be included in the ink as a pigment dispersion. A dispersant can be used to disperse the pigment in a liquid medium. Dispersants can generally be used as known substances. From the perspective of dispersion stability, the dispersant is preferably a compound having both a hydrophilic structure and a hydrophobic structure.

[0085] Examples of the dispersant include low molecular weight dispersants having a molecular weight of less than 1000, such as higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalenesulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, polyoxyalkylene alkylphenyl ethers, polyoxyethylene polyoxypropylene glycols, glycerol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene fatty acid amides, and amine oxides.

[0086] In addition, examples of dispersants include high molecular weight dispersants with a molecular weight of 1000 or more obtained by copolymerizing a hydrophilic monomer and a hydrophobic monomer. From the perspective of dispersion stability, the hydrophilic monomer is preferably a dissociative group-containing monomer, preferably a dissociative group-containing monomer having a dissociative group and an ethylenically unsaturated bond. Examples of dissociative group-containing monomers include carboxyl group-containing monomers, sulfonic acid group-containing monomers, and phosphoric acid group-containing monomers. From the perspective of dispersion stability, the hydrophobic monomer is preferably an aromatic group-containing monomer having an aromatic group and an ethylenically unsaturated bond, or an aliphatic hydrocarbon group-containing monomer having an aliphatic hydrocarbon group and an ethylenically unsaturated bond. The polymer may be either a random copolymer or a block copolymer.

[0087] The dispersant may be a commercially available product. Examples of commercially available products include:

[0088] DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-110, DISPERBYK-111, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DI SPERBYK-164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-182 (the above, manufactured by BYK-Chemie); and

[0089] SOLSPERSE3000, SOLSPERSE5000, SOLSPERSE9000, SOLSPERSE12000, SOLSPERSE13240, SOLSPERSE13940, SOLSPERSE17000, SOLSPERSE22000, SOLSPERSE 24000, SOLSPERSE26000, SOLSPERSE28000, SOLSPERSE32000, SOLSPERSE36000, SOLSPERSE39000, SOLSPERSE41000, SOLSPERSE71000 (the above, made by Lubrizol).

[0090] As a dispersing device for dispersing the pigment, a known dispersing device can be used, and examples thereof include a ball mill, a sand mill, a bead mill, a roll mill, a jet mill, a paint shaker, an attritor, an ultrasonic disperser, and a disperser.

[0091] In the ink, the content of the dispersant relative to the content of the pigment is preferably 0.05 to 1.0, more preferably 0.1 to 0.5, in terms of mass standard, from the viewpoint of dispersion stability.

[0092] <Silicone surfactants having a (meth)acryloyl group>

[0093] The ink according to one embodiment of the present disclosure contains a silicone-based surfactant having at least one (meth)acryloyl group.

[0094] When the ink contains a silicone surfactant with a (meth)acryloyl group, the resulting ink film exhibits surface activity. For example, when the image recorded material is immersed in a treatment liquid (e.g., an alkaline aqueous solution), the adhesion between the substrate and the ink film decreases, causing the ink film to peel from the substrate. Because the ink film has surface activity, it easily floats after being peeled from the substrate, resulting in excellent separation properties.

[0095] The number of the (meth)acryloyl group contained in the silicone-based surfactant having a (meth)acryloyl group may be only one, or may be two or more.

[0096] From the viewpoint of separability, the number of (meth)acryloyl groups is preferably 2 or more, more preferably 3 or more. The upper limit of the number of (meth)acryloyl groups is not particularly limited, but is, for example, 5 from the viewpoint of ejectability.

[0097] The silicone surfactant having a (meth)acryloyl group is preferably a polyether-modified polydimethylsiloxane having a (meth)acryloyl group. In the polyether-modified polydimethylsiloxane having a (meth)acryloyl group, the position of the polyether chain is not particularly limited and may be at one end of the main chain, at both ends of the main chain, or in a side chain. The polyether chain is preferably a polyoxyalkylene chain.

[0098] Examples of commercially available silicone surfactants having a (meth)acryloyl group include BYK-UV 3500, 3505, 3530, 3570, 3575, and 3576 (manufactured by BYK), Tegorad 2100, 2200, 2250, 2300, 2500, 2600, 2700, 2800, 2010, and 2011 (manufactured by Evonic), EBECRYL 350 and 1360 (manufactured by DAICEL-ALLNEX), and KP-410, 411, 412, 413, 414, 415, 416, 418, 420, 422, and 423 (manufactured by Shin-Etsu Silicone Co., Ltd.).

[0099] From the perspective of separability, the silicone surfactant having a (meth)acryloyl group contains a polyether structure and a polysiloxane structure, and the mass ratio of the polysiloxane structure to the polyether structure is preferably 0.5 or more, more preferably 0.6 or more. The upper limit of the above mass ratio is, for example, 0.95.

[0100] The mass ratio of the polysiloxane structure content to the polyether structure content was determined by nuclear magnetic resonance spectroscopy. 1 H-NMR) calculations were performed.

[0101] From the viewpoint of separability, the content of the silicone surfactant having a (meth)acryloyl group is preferably 0.5% by mass to 10% by mass, and more preferably 4% by mass to 7% by mass, relative to the total amount of the ink.

[0102] <Acrylic resin with a glass transition temperature of 30°C or higher>

[0103] The ink according to one embodiment of the present disclosure contains at least one acrylic resin having a glass transition temperature of 30° C. or higher (hereinafter also referred to as “specific acrylic resin”).

[0104] In the present disclosure, the acrylic resin refers to a resin containing at least one of a structural unit derived from (meth)acrylic acid and a structural unit derived from (meth)acrylate.

[0105] When the ink contains a specific acrylic resin, the surface hardness of the ink film increases, and thus it is considered that the scratch resistance is excellent.

[0106] From the perspective of further improving scratch resistance, the glass transition temperature of the specific acrylic resin is preferably 35°C or higher, more preferably 65°C or higher. The upper limit of the glass transition temperature is not particularly limited, but from the perspective of ejectability, the glass transition temperature is preferably 140°C or lower, more preferably 100°C or lower.

[0107] In the present disclosure, the glass transition temperature of a specific acrylic resin refers to a value measured using differential scanning calorimetry (DSC). As a differential scanning calorimeter (DSC), for example, EXSTAR 6220 (manufactured by Seiko Nanotechnology Co., Ltd.) is used.

[0108] When the ink contains two or more specific acrylic resins, the glass transition temperature (Tg) refers to the weighted average value of the glass transition temperatures of the respective acrylic resins.

[0109] From the viewpoint of scratch resistance, the weight average molecular weight of the specific acrylic resin is preferably 5,000 to 100,0000, more preferably 10,000 to 50,000.

[0110] In the present disclosure, the weight average molecular weight is measured using gel permeation chromatography (GPC). For example, HLC-8220GPC (manufactured by Tosoh Corporation) is used as GPC, three TSKgel SuperAWM-H (manufactured by Tosoh Corporation, 6.0 mm I.D. × 15 cm) are used as chromatographic columns, and N-methylpyrrolidone (10 mM LiBr added) is used as eluent. The conditions are that the sample concentration is set to 0.1% by mass, the flow rate is set to 0.5 mL / min, the sample injection amount is set to 60 μl, the measurement temperature is set to 40 ° C, and a differential refractive index (RI) detector is used for detection. The calibration curve is made using the product name "TSK standard polystyrene" manufactured by Tosoh Corporation: 8 samples of "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000" and "n-propylbenzene" as standard samples.

[0111] From the viewpoint of achieving a glass transition temperature of 30° C. or higher, the specific acrylic resin preferably contains a structural unit derived from at least one selected from the group consisting of a (meth)acrylate containing a linear or branched aliphatic hydrocarbon group and a (meth)acrylate containing an alicyclic hydrocarbon group, and more preferably contains a structural unit derived from a (meth)acrylate containing a linear or branched aliphatic hydrocarbon group and a structural unit derived from a (meth)acrylate containing an alicyclic hydrocarbon group.

[0112] Examples of the (meth)acrylate containing a linear or branched aliphatic hydrocarbon group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, isododecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and behenyl (meth)acrylate.

[0113] Examples of the alicyclic hydrocarbon group-containing (meth)acrylate include cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclononyl (meth)acrylate, cyclodecyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, and adamantyl (meth)acrylate.

[0114] The mass ratio of the content of the silicone surfactant having a (meth)acryloyl group to the content of the specific acrylic resin is preferably 1 to 10, more preferably 4 to 7. When the mass ratio is 1 or greater, the ejectability is improved. When the mass ratio is 10 or less, the scratch resistance is improved.

[0115] From the viewpoint of scratch resistance, the content of the specific acrylic resin is preferably 0.2% by mass to 3% by mass, and more preferably 0.5% by mass to 1.5% by mass, relative to the total amount of the ink.

[0116] <Polymerization initiator>

[0117] The ink according to one embodiment of the present disclosure may contain at least one polymerization initiator. The polymerization initiator is preferably a free radical polymerization initiator that generates free radicals.

[0118] Examples of the radical polymerization initiator include alkylphenol compounds, acylphosphine compounds, aromatic onium salt compounds, organic peroxides, sulfur compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, aziridinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

[0119] Among them, the polymerization initiator is preferably at least one selected from the group consisting of acylphosphine compounds and sulfur compounds, more preferably at least one selected from the group consisting of acylphosphine oxide compounds and thioxanthone compounds, and even more preferably a combination of acylphosphine oxide compounds and thioxanthone compounds.

[0120] Examples of the acylphosphine oxide compound include monoacylphosphine oxide compounds and bisacylphosphine oxide compounds.

[0121] Examples of the monoacylphosphine oxide compound include isobutyryldiphenylphosphine oxide, 2-ethylhexanoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, o-toluoyldiphenylphosphine oxide, p-tert-butylbenzoyldiphenylphosphine oxide, 3-pyridylcarbonyldiphenylphosphine oxide, acryloyldiphenylphosphine oxide, benzoyldiphenylphosphine oxide, vinyl tert-valeroylphenylphosphine oxide, adipylbisdiphenylphosphine oxide, tert-valeroyldiphenylphosphine oxide, p-toluoyldiphenylphosphine oxide, 4-(tert-butyl)benzoyldiphenylphosphine oxide, terephthaloylbisdiphenylphosphine oxide, 2-methylbenzoyldiphenylphosphine oxide, neodecanoyldiphenylphosphine oxide, and versatoyldiphenylphosphine oxide. oxide), 2-methyl-2-ethylhexanoyl diphenylphosphine oxide, 1-methyl-cyclohexanoyl diphenylphosphine oxide, methyl tert-valeryl phenylphosphonate, and isopropyl tert-valeryl phenylphosphonate.

[0122] Examples of the bisacylphosphine oxide compound include bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-ethoxyphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, bis(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, and bis(2,6-dichlorobenzoyl)-4-ethoxyphenylphosphine oxide. 1-naphthylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-chlorophenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,4-dimethoxyphenylphosphine oxide, bis(2,6-dichlorobenzoyl)decylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-octylphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)-2, 5-dimethylphenylphosphine oxide, bis(2,6-dichloro-3,4,5-trimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichloro-3,4,5-trimethoxybenzoyl)-4-ethoxyphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis(2-methyl-1- phenylphosphine oxide, bis(2-methyl-1-naphthoyl)-4-propylphenylphosphine oxide, bis(2-methyl-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, bis(2-methoxy-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis(2-chloro-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0123] Examples of the thioxanthone compound include thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)thioxanthone, 4-butoxycarbonylthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfonylthioxanthone, 3,4-bis[2-(2-methylthioxanthone)] 1-Methyl-1-morpholinoethyl thioxanthone, 2-methyl-6-dimethoxymethyl thioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl) thioxanthone, 2-morpholinomethyl thioxanthone, 2-methyl-6-morpholinomethyl thioxanthone, n-allyl thioxanthone-3,4-dicarboximide, n-octyl thioxanthone-3,4-dicarboxylic acid imide, N-(1,1,3,3-tetramethylbutyl)thioxanthone-3,4-dicarboxylic imide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol ester and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-acyloxy)-N,N,N-trimethyl-1-propane ammonium chloride.

[0124] The thioxanthone compound may be a commercially available product, and examples of the commercially available product include the SPEEDCURE series manufactured by Lambson (for example, SPEEDCURE 7010, SPEEDCURE CPTX, SPEEDCURE ITX, etc.).

[0125] From the viewpoint of further reducing odor, the ink according to one embodiment of the present disclosure preferably contains at least one selected from the group consisting of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide as a polymerization initiator, and more preferably contains phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide.

[0126] Furthermore, from the viewpoint of further reducing odor, the total content of at least one selected from the group consisting of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide (preferably the total content of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide) is preferably 3.5% by mass or more, more preferably 5% by mass or more, relative to the total amount of the ink. The upper limit of the above-mentioned total content is not particularly limited, and is, for example, 10% by mass.

[0127] Furthermore, from the viewpoint of further reducing odor, the ink according to one embodiment of the present disclosure preferably contains a compound having two or more thioxanthone skeletons in its molecule as a polymerization initiator.

[0128] The content of the compound having two or more thioxanthone skeletons in the molecule is preferably 1% by mass to 10% by mass, more preferably 2% by mass to 8% by mass, relative to the total amount of the ink.

[0129] <Polymerization inhibitor>

[0130] The ink according to one embodiment of the present disclosure preferably contains at least one polymerization inhibitor.

[0131] Examples of the polymerization inhibitor include hydroquinone compounds, phenothiazines, catechols, alkylphenols, alkylbisphenols, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionate, mercaptobenzimidazole, phosphites, nitrosoamine compounds, hindered amine compounds, and nitroxyl radicals.

[0132] Among them, the polymerization inhibitor is more preferably a nitrosoamine compound.

[0133] Examples of the nitrosoamine compound include N-nitroso-N-phenylhydroxylamine aluminum salt and N-nitroso-N-phenylhydroxylamine. Among them, the nitrosoamine compound is preferably N-nitroso-N-phenylhydroxylamine aluminum salt.

[0134] From the viewpoint of improving the temporal stability of the ink, the content of the polymerization inhibitor is preferably 0.05% by mass to 1% by mass relative to the total amount of the ink.

[0135] <Additives>

[0136] The ink according to one embodiment of the present disclosure may contain additives such as a co-sensitizer, an ultraviolet absorber, an antioxidant, an anti-fading agent, a conductive salt, a solvent, and a basic compound as needed.

[0137] <Physical Properties>

[0138] The viscosity of the ink is preferably 0.5 mPa·s to 50 mPa·s, more preferably 5 mPa·s to 40 mPa·s, preferably 7 mPa·s to 35 mPa·s, and even more preferably 8 mPa·s to 30 mPa·s. The viscosity is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0139] The surface tension of the ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 45 mN / m. The surface tension is measured at 25°C using a surface tensiometer, for example, an automatic surface tensiometer manufactured by Kyowa Interface Science Co., Ltd. (product name "CBVP-Z"), using a plate method.

[0140] [Active energy ray curable ink set]

[0141] An ink set as one embodiment of the present disclosure includes a first ink and a second ink.

[0142] The first ink is one form of ink as one embodiment of the present disclosure, and the colorant is a pigment other than the white pigment.

[0143] The second ink is one form of ink as one embodiment of the present disclosure, and the colorant is a white pigment.

[0144] Preferred aspects of the first ink and the second ink are the same as preferred aspects of the ink as one embodiment of the present disclosure except for the following details.

[0145] Examples of pigments other than the white pigment include a cyan pigment, a magenta pigment, a yellow pigment, and a black pigment.

[0146] Examples of the white pigment include titanium dioxide, barium sulfate, calcium carbonate, silicon dioxide, zinc oxide, zinc sulfide, mica, talc, and pearl.

[0147] From the perspective of hiding power, the average primary particle size of the white pigment is preferably 150 nm or greater, more preferably 200 nm or greater. Furthermore, from the perspective of ink jetting properties, the average primary particle size of the white pigment is preferably 400 nm or less, more preferably 350 nm or less. The average primary particle size of the white pigment is preferably 150 nm to 400 nm.

[0148] In this disclosure, the average primary particle size of a white pigment is a value measured using a transmission electron microscope (TEM). Specifically, 50 random white pigments present within a field of view observed by a TEM are selected, and the 50 primary particle sizes are measured and averaged. As a transmission electron microscope, a transmission electron microscope 1200EX manufactured by JEOL Ltd. can be used.

[0149] From the viewpoint of improving water resistance, when the first ink and the second ink have the same mass, the content of the specific acrylic resin in the first ink is preferably greater than the content of the specific acrylic resin in the second ink.

[0150] Specifically, the mass ratio of the content of the specific acrylic resin in the first ink to the content of the specific acrylic resin in the second ink is preferably 2 or more, more preferably 5 or more. The upper limit of the mass ratio is 15, for example.

[0151] The content of the specific acrylic resin in the first ink is preferably 0.2% by mass to 3% by mass, and more preferably 0.5% by mass to 1.5% by mass, based on the total amount of the first ink.

[0152] The content of the specific acrylic resin in the second ink is preferably 0.1% by mass to 1% by mass, and more preferably 0.3% by mass to 1% by mass, based on the total amount of the second ink.

[0153] The ink set according to one embodiment of the present disclosure preferably further includes, in addition to the first ink and the second ink, a third ink containing at least one acid group-containing compound selected from the group consisting of polymerizable monomers having an acid group and polymers having an acid group.

[0154] <Acid group-containing compounds>

[0155] When the acid group reacts with a base to form a salt, the water solubility is improved. The third ink is preferably applied directly to the substrate. When the third ink contains an acid group-containing compound, the alkali releasability is improved.

[0156] Examples of the acid group in the acid group-containing compound include a carboxyl group, a sulfo group, a phosphonic acid group, a phosphoric acid group, and a sulfonamide group.

[0157] —Polymerizable monomer having an acid group—

[0158] In this disclosure, a "monomer" refers to a compound with a molecular weight of less than 1000. A "polymerizable monomer" refers to a compound with a molecular weight of less than 1000 and having a polymerizable group. The molecular weight of a monomer can be calculated based on the types and numbers of atoms constituting the monomer.

[0159] Examples of the polymerizable monomer having a carboxyl group include 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylphthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-carboxyethyl(meth)acrylate, and (meth)acrylic acid.

[0160] Examples of the polymerizable monomer having a sulfonic group include 2-hydroxy-3-sulfopropyl (meth)acrylate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, 2-sulfoethyl (meth)acrylate, 3-sulfopropyl (meth)acrylate, and 4-styrenesulfonic acid.

[0161] Examples of the polymerizable monomer having a phosphoric acid group include 2-phosphonooxyethyl (meth)acrylate and 2-(meth)acryloyloxyethyl acid phosphate.

[0162] Among these, from the viewpoints of improvement in alkali peelability, safety, and low viscosity, the polymerizable monomer having an acid group is preferably a polymerizable monomer having a carboxyl group.

[0163] The polymerizable monomer having an acid group may be a monofunctional polymerizable monomer having an acid group or a polyfunctional polymerizable monomer having an acid group. From the viewpoint of improved alkali stripping properties, safety, and low viscosity, a monofunctional polymerizable monomer having an acid group is preferred, a monofunctional polymerizable monomer having a carboxyl group is more preferred, and a monofunctional (meth)acrylate having a carboxyl group is further preferred.

[0164] —Polymers having acid groups—

[0165] In the present disclosure, "polymer" means a compound having a weight average molecular weight of 1,000 or more.

[0166] Examples of the polymer having an acid group include (meth)acrylic copolymers, polyurethanes, polyvinyl alcohols, polyvinyl butyrals, polyvinyl formals, polyamides, polyesters, and epoxy resins. Among them, the polymer having an acid group is preferably a (meth)acrylic copolymer, polyurethane, or polyvinyl butyral.

[0167] In the present disclosure, a (meth)acrylic copolymer refers to a copolymer containing (meth)acrylic acid, (meth)acrylic acid esters (e.g., alkyl (meth)acrylates, aryl (meth)acrylates, allyl (meth)acrylates, etc.), (meth)acrylamide, (meth)acrylamide derivatives, and other (meth)acrylamide derivatives as structural units. Polyurethane refers to a polymer obtained by the condensation reaction of a polyfunctional isocyanate compound having two or more isocyanate groups with a polyol having two or more hydroxyl groups. Polyvinyl butyral refers to a polymer obtained by reacting polyvinyl alcohol obtained by partially or completely saponifying polyvinyl acetate with butyraldehyde under acidic conditions. Polyvinyl butyral also includes polymers having functional groups introduced into the molecule.

[0168] The (meth)acrylic acid copolymer preferably contains a structural unit having an acid group. Among them, the acid group is preferably a carboxyl group. Examples of the structural unit having a carboxyl group include a structural unit derived from (meth)acrylic acid and a structural unit derived from a structural unit represented by the following formula 1.

[0169] [Chemical Formula 1]

[0170]

[0171] In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a single bond or an n+1 valent linking group. A represents an oxygen atom or -NR 3 -, R 3 represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. n represents an integer of 1 to 5.

[0172] For preferred embodiments and specific examples of the structural unit represented by formula (1), and preferred embodiments of structural units other than the structural unit represented by formula (1), reference can be made to Japanese Patent Nos. 4668111 and 5588887.

[0173] Among them, the polymer having an acid group preferably contains a structural unit derived from (meth)acrylic acid and a structural unit derived from an alkyl (meth)acrylate. The alkyl group contained in the alkyl (meth)acrylate preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms.

[0174] The weight average molecular weight of the polymer having an acid group is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000, and even more preferably 10,000 to 200,000.

[0175] From the perspective of further improving alkali stripping properties, the total content of the acid group-containing compounds is preferably 8% by mass or more, more preferably 10% by mass or more, and even more preferably 14% by mass or more relative to the total amount of the third ink. The upper limit of the above total content is, for example, 20% by mass.

[0176] <Bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms>

[0177] The third ink preferably contains a specific bifunctional (meth)acrylate. Preferred embodiments of the specific bifunctional (meth)acrylate contained in the third ink are the same as preferred embodiments of the specific bifunctional (meth)acrylate contained in the ink as one embodiment of the present disclosure.

[0178] <Monofunctional (meth)acrylate having a hydroxyl group>

[0179] The third ink preferably contains a specific monofunctional (meth)acrylate. Preferred embodiments of the specific monofunctional (meth)acrylate contained in the third ink are the same as preferred embodiments of the specific monofunctional (meth)acrylate that may be contained in the ink as one embodiment of the present disclosure.

[0180] <Other polymerizable compounds>

[0181] The third ink may contain other polymerizable compounds.

[0182] Examples of the other polymerizable compound contained in the third ink include the same polymerizable compounds as those contained in the ink according to one embodiment of the present disclosure.

[0183] <Acrylic resin with a glass transition temperature of 30°C or higher>

[0184] The third ink preferably contains a specific acrylic resin. Preferred embodiments of the specific acrylic resin contained in the third ink are the same as preferred embodiments of the specific acrylic resin contained in the ink as one embodiment of the present disclosure.

[0185] When the first, second, and third inks have the same mass, the specific acrylic resin content (Mc) in the first ink is preferably greater than the specific acrylic resin content (Mw) in the second ink, and the specific acrylic resin content (Mc) in the first ink is preferably greater than the specific acrylic resin content (Mp) in the third ink. Furthermore, it is more preferable that the specific acrylic resin content in the second ink is greater than the specific acrylic resin content in the third ink.

[0186] Among them, preferably 1<Mc / Mw≤4, more preferably 1.5≤Mc / Mw≤3. Also, preferably 1<Mc / Mp≤10, more preferably 2≤Mc / Mp≤8.

[0187] For example, when the third ink, the second ink, and the first ink are sequentially applied to a substrate, the ink film formed by the first ink is positioned outermost. If the acrylic resin content in the first ink is greater than the specific acrylic resin content in the second and third inks, water resistance is improved.

[0188] <Polymerization initiator>

[0189] The third ink may contain at least one polymerization initiator.

[0190] Examples of the polymerization initiator contained in the third ink include the same polymerization initiators as those contained in the ink according to one embodiment of the present disclosure.

[0191] <Polymerization inhibitor>

[0192] The third ink preferably contains at least one polymerization inhibitor.

[0193] Examples of the polymerization inhibitor contained in the third ink include the same polymerization inhibitors as those contained in the ink according to one embodiment of the present disclosure.

[0194] From the viewpoint of improving the temporal stability of the third ink, the content of the polymerization inhibitor is preferably 0.05% by mass to 0.5% by mass relative to the total amount of the third ink.

[0195] Surfactants

[0196] The third ink preferably contains at least one surfactant.

[0197] Examples of the surfactant contained in the third ink include the same surfactants as the silicone-based surfactant having a (meth)acryloyl group contained in the ink according to one embodiment of the present disclosure.

[0198] <Additives>

[0199] The third ink may contain additives such as a co-sensitizer, an ultraviolet absorber, an antioxidant, an anti-fading agent, a conductive salt, a solvent, and a basic compound as needed.

[0200] The third ink preferably does not contain a colorant. The third ink preferably functions as a primer for removing the image recorded with the first ink and the second ink with an alkali.

[0201] <Physical Properties>

[0202] The viscosity of the third ink is preferably 0.5 mPa·s to 50 mPa·s, more preferably 5 mPa·s to 40 mPa·s, further preferably 7 mPa·s to 35 mPa·s, and particularly preferably 8 mPa·s to 30 mPa·s.

[0203] The surface tension of the third ink is preferably 60 mN / m or less, more preferably 20 mN / m to 40 mN / m, and even more preferably 23 mN / m to 30 mN / m.

[0204] [Image Recording Method A]

[0205] Image recording method A as one embodiment of the present disclosure includes the steps of applying the above-mentioned ink (ink as one embodiment of the present disclosure) to a substrate using an inkjet recording method; and irradiating the applied ink with active energy rays.

[0206] (Process of applying using inkjet recording method)

[0207] The type of substrate is not particularly limited, and generally known substrates can be used as the substrate. Examples of the substrate include glass, quartz, and plastic films. Examples of the resin constituting the plastic film include cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, acrylic resins, chlorinated polyolefin resins, polyethersulfone resins, polyethylene terephthalate (PET), polyethylene naphthalate, nylon, polyethylene, polystyrene, polypropylene, polycycloolefin resins, polyimide resins, polycarbonate resins, and polyvinyl acetal. The plastic film may be a film containing only one of these resins, or a film formed by mixing two or more of these resins.

[0208] The thickness of the substrate is not particularly limited, and is, for example, 1 μm to 10 mm. When the substrate is a film, the thickness is preferably 1 μm to 500 μm, more preferably 2 μm to 200 μm, even more preferably 5 μm to 100 μm, and particularly preferably 10 μm to 90 μm. Furthermore, when the substrate is glass, the thickness is preferably 0.1 mm to 10 mm, more preferably 0.15 mm to 8 mm, and even more preferably 0.2 mm to 5 mm.

[0209] The substrate may be a beverage container.

[0210] The material of the beverage container is not particularly limited, and examples thereof include glass and plastic. Among them, the beverage container is preferably a plastic container, preferably a PET bottle containing polyethylene terephthalate as a main component.

[0211] Alternatively, the substrate may be a plastic film attached to the surface of the beverage container. The substrate may be subjected to a hydrophilic treatment. Examples of hydrophilic treatments include, but are not limited to, corona treatment, plasma treatment, heat treatment, abrasion treatment, light irradiation treatment (e.g., UV treatment), and flame treatment. Corona treatment can be performed, for example, using Corona Master (product name "PS-10S," manufactured by Shinko Electric Instrument Co., Ltd.). Corona treatment conditions can be appropriately selected depending on the type of substrate.

[0212] Inkjet recording methods are not particularly limited as long as they can record images, and known methods can be used. Examples of inkjet recording methods include: a charge control method that utilizes electrostatic attraction to eject ink; a drop-on-demand method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element; an acoustic inkjet method that converts an electrical signal into an acoustic beam and irradiates the ink, ejecting the ink using the radiation pressure; and a thermal inkjet method (Bubble Jet (registered trademark)) that utilizes the pressure generated by heating the ink to form bubbles.

[0213] As inkjet heads used for inkjet recording, the following methods can be cited: a shuttle method using a long serial print head to record while scanning the print head in the width direction of the substrate; and a linear method using a line head with recording elements arranged corresponding to the entire area of ​​one side of the substrate.

[0214] The linear method allows patterning to be formed across the entire surface of a substrate by scanning the substrate in a direction intersecting the arrangement of the recording elements. This eliminates the need for a transport system such as a carriage for scanning with a long strip head. Furthermore, the linear method eliminates the need for complex scanning control between the carriage and the substrate; only the substrate moves, thus achieving higher recording speeds compared to the shuttle method.

[0215] The droplet amount of the ink ejected from the inkjet head is preferably 1 pL (picoliter) to 100 pL, more preferably 3 pL to 80 pL, and even more preferably 3 pL to 50 pL.

[0216] (Step of irradiating the applied ink with active energy rays)

[0217] Examples of active energy rays include gamma rays, beta rays, electron beams, ultraviolet rays, and visible light rays. Among them, ultraviolet rays are preferred.

[0218] The peak wavelength of ultraviolet rays is, for example, preferably 200 nm to 405 nm, more preferably 250 nm to 400 nm, and even more preferably 300 nm to 400 nm.

[0219] As light sources for ultraviolet irradiation, various lasers such as mercury lamps, gas lasers, and solid-state lasers are mainly used. Discharge lamps such as mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps are widely known. In addition, semiconductor light sources such as UV-LEDs (ultraviolet light-emitting diodes) and UV-LDs (ultraviolet laser diodes) are expected to be used as light sources for ultraviolet irradiation due to their compact size, long life, high efficiency, and low cost. Among them, the light source for ultraviolet irradiation is preferably a metal halide lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, or a UV-LED.

[0220] In the present disclosure, the operation of polymerizing only a portion of the polymerizable monomers in the ink is also referred to as “temporary curing”, and the irradiation with active energy rays for the temporary curing is also referred to as “pinning exposure”.

[0221] In the present disclosure, the operation of polymerizing substantially all of the polymerizable compound in the ink is also referred to as “main curing”, and the irradiation with active energy rays for the main curing is also referred to as “main exposure”.

[0222] In the step of irradiating the active energy ray, it is preferred to temporarily cure the ink and then perform the main curing. Specifically, it is preferred to perform fixing exposure on the ink after applying the ink and finally perform the main exposure.

[0223] The reaction rate of the ink after fixed exposure is preferably 10% to 80%.

[0224] Here, the reaction rate of the ink means the polymerization rate of the polymerizable compound contained in the ink determined by high performance liquid chromatography.

[0225] When the ink reaction rate is 10% or more, the dot expansion is insufficiently suppressed, resulting in increased graininess of the image finally obtained.

[0226] In addition, since the reaction rate of the ink is 80% or less, the interference between the ink dots can be suppressed.

[0227] As a result, the quality of the final image is improved.

[0228] From the viewpoint of further improving the graininess of the finally obtained image, the reaction rate of the ink is preferably 15% or more.

[0229] From the viewpoint of further improving the quality of the final image, the reaction rate of the ink is preferably 75% or less, more preferably 50% or less, preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less.

[0230] The reaction rate of the ink after the main exposure is preferably more than 80% and 100% or less, more preferably 85% to 100%, and even more preferably 90% to 100%.

[0231] When the reaction rate exceeds 80%, the adhesion is further improved.

[0232] The reaction rate of the ink was determined by the following method.

[0233] A substrate was prepared and subjected to the following procedures until the ink was irradiated with active energy rays. A 20 mm x 50 mm sample piece (hereinafter referred to as the irradiated sample piece) was cut from the area of ​​the substrate where the ink film was present. The irradiated sample piece was immersed in 10 mL of THF (tetrahydrofuran) for 24 hours to obtain an eluate containing the ink. The amount of polymerizable compound in the obtained eluate (hereinafter referred to as "post-irradiation monomer amount X1") was determined using high-performance liquid chromatography.

[0234] The same operation as above was carried out except that the ink on the substrate was not irradiated with active energy rays, and the amount of the polymerizable compound (hereinafter referred to as "monomer amount before irradiation X1") was determined.

[0235] Based on the monomer amount X1 after irradiation and the monomer amount X1 before irradiation, the reaction rate (%) of the ink was determined by the following formula.

[0236] Reaction rate of ink (%) = ((monomer amount before irradiation X1 - monomer amount after irradiation X1) / monomer amount before irradiation X1) × 100

[0237] From the viewpoint of achieving the above-mentioned ink reaction rate more easily, the exposure dose of the active energy ray for fixed exposure is preferably 10 mJ / cm 2 ~100mJ / cm 2 , more preferably 20 mJ / cm 2 ~60mJ / cm 2 .

[0238] From the viewpoint of completely curing the ink, the exposure dose of the active energy ray used for the main exposure is preferably 50 mJ / cm 2 ~1000mJ / cm 2 , more preferably 200 mJ / cm 2 ~800mJ / cm 2 .

[0239] In the main exposure, from the viewpoint of improving adhesion to the substrate, active energy ray irradiation is preferably performed in an atmosphere with an oxygen concentration of less than 1 vol %. The oxygen concentration is more preferably 0.5 vol % or less, and even more preferably 0.3 vol % or less.

[0240] In the step of irradiating the active energy ray, from the perspective of image quality, it is preferred that the active energy ray be irradiated within 0.1 to 5 seconds from the time the ink lands. When performing both fixing exposure and main exposure, it is preferred that the active energy ray for fixing exposure be irradiated within 0.1 to 5 seconds from the time the ink lands. The time from the time the ink lands to the irradiation of the active energy ray (when performing both fixing exposure and main exposure, the active energy ray for fixing exposure) is more preferably within 0.2 to 1 second.

[0241] [Image recording method B]

[0242] The image recording method B as one embodiment of the present disclosure uses the above-mentioned ink group (the ink group as one embodiment of the present disclosure), which includes the following steps: imparting a second ink to a substrate by an inkjet recording method; irradiating the imparted second ink with active energy rays; imparting a first ink to the substrate imparted with the second ink by an inkjet recording method; and irradiating the imparted first ink with active energy rays.

[0243] The type of substrate, the method of applying ink by the inkjet recording method, and the method of irradiating active energy rays are the same as those in the above-mentioned image recording method A.

[0244] Hereinafter, points different from the image recording method A will be described.

[0245] In image recording method B, it is preferred to apply the second ink, then perform fixation exposure on the second ink, apply the first ink over the temporarily cured second ink, apply the first ink, then perform fixation exposure on the first ink, and finally perform main exposure. Temporarily curing the second ink improves the quality of the resulting image.

[0246] Image recording method B may further include applying a third ink to the substrate using an inkjet recording method, and irradiating the applied third ink with active energy rays. In this case, the second ink is preferably applied to the substrate applied with the third ink. Furthermore, it is preferred that after applying the third ink, the third ink is subjected to a fixation exposure, after applying the second ink, the second ink is subjected to a fixation exposure, the first ink is applied to the temporarily cured second ink, and after applying the first ink, the first ink is subjected to a fixation exposure, and finally, the main exposure is performed.

[0247] [Example]

[0248] Hereinafter, the present disclosure will be described in more detail with reference to Examples. However, the present disclosure is not limited to the following Examples unless it exceeds the scope of the present disclosure.

[0249] <Examples 1 to 34, Comparative Examples 1 to 5>

[0250] [Preparation of the First Ink and the Second Ink]

[0251] When preparing the first ink (cyan ink), first, a cyan pigment dispersion is prepared.

[0252] When preparing the second ink (white ink), first, a white pigment dispersion is prepared.

[0253] A cyan pigment (30 parts by mass), SOLSPERSE 32000 (9 parts by mass) as a dispersant, 3MPDDA (60 parts by mass) as a dispersant, and UV22 (1 part by mass) as an inhibitor were placed in a disperser Motor Mill M50 (manufactured by EIGER). Using zirconia beads with a diameter of 0.65 mm, a dispersion treatment was carried out at a peripheral speed of 9 m / s for 4 hours to obtain a cyan pigment dispersion.

[0254] When preparing the second ink (white ink), first, a white pigment dispersion is prepared.

[0255] A white pigment (60 parts by mass), SOLSPERSE 32000 (9 parts by mass) as a dispersant, 3MPDDA (30 parts by mass) as a dispersant, and UV22 (1 part by mass) as a polymerization inhibitor were placed in a disperser Motor Mill M50 (manufactured by EIGER). Using zirconia beads with a diameter of 0.65 mm, a dispersion treatment was carried out at a peripheral speed of 9 m / s for 4 hours to obtain a white pigment dispersion.

[0256] The details of the components contained in the cyan pigment dispersion and the white pigment dispersion are as follows.

[0257] Cyan pigment: CI Pigment Blue 15:4 (product name: "Heliogen (registered trademark) Blue D7110F", manufactured by Sun Chemical (DIC Corporation))

[0258] White pigment: titanium oxide (product name "KRONOS 2300", manufactured by KRONOS Corporation)

[0259] SOLSPERSE 32000: Polyethyleneimine dispersant (product name "SOLSPERSE 32000", manufactured by Lubrizol)

[0260] 3MPDDA: 3-methyl-1,5-pentanediol diacrylate (product name "SR341", manufactured by Sartomer)

[0261] UV22: A mixture of 2,6-bis(1,1-dimethylethyl)-4-(phenylmethylene)-2,5-cyclohexadien-1-one and propoxylated glycerol triacrylate (product name "IRGASTAB UV-22", manufactured by BASF)

[0262] In addition, although UV22 contains propoxylated glyceryl triacrylate as another polymerizable compound, since the content of propoxylated glyceryl triacrylate is very small, it is described in the column of "polymerization inhibitor" in the table.

[0263] Next, the prepared cyan pigment dispersion was mixed with the components listed in Tables 2 to 9 below so that the content of each component was the content (mass %) listed in Tables 2 to 9. The mixture was stirred at 25°C and 5000 rpm for 20 minutes using a mixer (product name "L4R", manufactured by Silverson) to obtain a first ink. Separately, the prepared white pigment dispersion was mixed with the components listed in the following table so that the content of each component was the content (mass %) listed in the table. The mixture was stirred at 25°C and 5000 rpm for 20 minutes using a mixer (product name "L4R", manufactured by Silverson) to obtain a second ink.

[0264] [Preparation of the third ink]

[0265] The components listed in Tables 2 to 9 below were mixed so that the content (mass %) of each component was the content listed in Tables 2 to 9. The mixture was stirred at 25°C and 5000 rpm for 20 minutes using a mixer (product name "L4R", manufactured by Silverson) to obtain a third ink.

[0266] The details of the components described in Tables 2 to 9 are as follows.

[0267] Speedcure 7010L (Lambson) was used in the ink preparation. Speedcure 7010L is a mixture of Speedcure 7010 and EOTMPTA, with a mass ratio of 1:1. Speedcure 7010 is a polymerization initiator, and EOTMPTA is another polymerizable compound. Therefore, they are described separately in the "Polymerization Initiator" and "Other Polymerizable Compound" columns.

[0268] <Specific bifunctional (meth)acrylate>

[0269] The specific bifunctional (meth)acrylate is a bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms.

[0270] 3MPDDA: As described above.

[0271] HDDA: 1,6-Hexanediol diacrylate (product name "VISCOAT#230", manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0272] NDDA: 1,9-Hexanediol diacrylate (product name "VISCOAT#260", manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0273] DDDA: 1,10-decanediol diacrylate (product name "SR595", manufactured by Sartomer)

[0274] BDDA: 1,4-Butanediol diacrylate (product name "VISCOAT#195", manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0275] <Specific monofunctional (meth)acrylate>

[0276] The specific monofunctional (meth)acrylate is a monofunctional (meth)acrylate having a hydroxyl group.

[0277] 4-HBA: 4-hydroxybutyl acrylate (product name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0278] <Polymerizable monomer having an acid group>

[0279] A-SA: 2-acryloyloxyethylsuccinic acid (product name: "NK Ester A-SA", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[0280] <Polymers having acid groups>

[0281] Polymer A: Binder A described in paragraph 0225 of Japanese Patent No. 5588887 (structural unit derived from methacrylic acid:structural unit derived from methyl methacrylate = 20:80)

[0282] <Other polymerizable compounds>

[0283] Other polymerizable compounds are polymerizable compounds other than the specific bifunctional (meth)acrylate, the specific monofunctional (meth)acrylate, and the polymerizable monomer having an acid group.

[0284] CTFA: Cyclic trimethylolpropane formal acrylate (product name "VISCOAT #200", manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0285] EOTMPTA: Trimethylolpropane EO-added triacrylate (50% by mass in "Speedcure 7010L", manufactured by Lambson)

[0286] PEG400DA: Polyethylene glycol diacrylate (product name "SR344, manufactured by Sartomer)

[0287] <Polymerization initiator>

[0288] BAPO: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad 819", manufactured by IGM Resins BV)

[0289] Speedcure 7010: 1,3-bis({α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methylethylidene)]}oxy)-2,2-bis({α-[1-methylethylidene)]}oxymethyl)propane (50% by mass of "Speedcure 7010L", manufactured by Lambson)

[0290] <Polymerization inhibitor>

[0291] UV12: N-nitroso-N-phenylhydroxylamine aluminum salt (product name "FLORSTAB UV-12", manufactured by Kromachem Co., Ltd.)

[0292] UV22: As described above.

[0293] Silicone surfactants

[0294] The mass ratio M of the content of the polysiloxane structure to the content of the polyether structure is as follows.

[0295] Tegorad 2010: (Meth)acryloyl-containing silicone surfactant (product name "Tegorad 2010," manufactured by Evonik, mass ratio M: 0.627119)

[0296] Tegorad 2500: (meth)acryloyl-containing silicone surfactant (product name "Tegorad 2500," manufactured by Evonik, mass ratio M: 0.937369)

[0297] Tegorad 2100: (meth)acryloyl-containing silicone surfactant (product name "Tegorad 2100", manufactured by Evonik, mass ratio M: 0.355208)

[0298] Tegorad 2200N: (Meth)acryloyl-containing silicone surfactant (product name "Tegorad 2200N", manufactured by Evonik, mass ratio M: 0.36319)

[0299] Tegorad 2250: (meth)acryloyl-containing silicone surfactant (product name "Tegorad 2250", manufactured by Evonik, mass ratio M: 0.451587)

[0300] Tegorad 2300: (meth)acryloyl-containing silicone surfactant (product name "Tegorad 2300", manufactured by Evonik, mass ratio M: 0.612617)

[0301] Colorants

[0302] Cyan pigment: as described above.

[0303] White pigment: as described above.

[0304] Dispersants

[0305] SOLSPERSE 32000: As described above.

[0306] <Acrylic resin>

[0307] BR113: Product name "DIANAL BR113", manufactured by Mitsubishi Chemical Corporation, glass transition temperature 75°C, weight average molecular weight 30,000

[0308] Polymer A to Polymer I: Acrylic resin synthesized by the following method

[0309] —Synthesis of Polymer A—

[0310] 20 g of a mixed solution of methyl methacrylate and isobornyl acrylate and 30 g of methyl ethyl ketone were introduced into a nitrogen-purged three-necked flask, stirred with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.), and heated to 65°C while nitrogen was flowing into the flask.

[0311] To the mixed liquid was added 80 mg of 2,2′-azobis(2,4-dimethylvaleronitrile) (product name “V-65”, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the mixture was stirred at 65° C. for 30 minutes.

[0312] 80 mg of V-65 was added, and the mixture was further stirred at 65°C for 1 hour.

[0313] The obtained reaction solution was poured into 1000 mL of hexane while stirring, and the generated precipitate was dried by heating to obtain a polymer A. The weight average molecular weight of the polymer A was 30,000 to 35,000.

[0314] —Synthesis of Polymers B to I—

[0315] Polymers B to I were obtained by using the polymerizable monomers having the mass (g) listed in Table 1 in the same manner as in the synthesis of polymer A, with appropriate changes in the amount of V-65 added and the heating time.

[0316] Generally, increasing the amount of V-65 results in a lower weight-average molecular weight of the resulting polymer. Reducing the amount of V-65 results in a higher weight-average molecular weight of the resulting polymer. Furthermore, increasing the heating time results in a higher weight-average molecular weight of the resulting polymer. Shortening the heating time results in a lower weight-average molecular weight of the polymer.

[0317] The details of the polymerizable monomers used for synthesizing Polymers A to I are as follows.

[0318] Isobornyl methacrylate (product name "LIGHT ESTERIB-X", manufactured by Kyoeisha Chemical Co., Ltd.)

[0319] Tert-butyl methacrylate (product name "LIGHT ESTER TB", manufactured by Kyoeisha Chemical Co., Ltd.)

[0320] 2-Phenoxyethyl methacrylate (product name "SR340", manufactured by Sartomer)

[0321] 2-Ethylhexyl methacrylate (product name "LIGHT ESTER EH", manufactured by Kyoeisha Chemical Co., Ltd.)

[0322] Isodecyl methacrylate (product name "LIGHT ESTER ID", manufactured by Kyoeisha Chemical Co., Ltd.)

[0323] n-Lauryl methacrylate (product name "LIGHT ESTER L", manufactured by Kyoeisha Chemical Co., Ltd.)

[0324] n-Butyl methacrylate (product name "LIGHT ESTER NB", manufactured by Kyoeisha Chemical Co., Ltd.)

[0325] Methyl methacrylate (product name "M0087", manufactured by Tokyo Chemical Industry Co., Ltd.)

[0326] —Weight average molecular weight of acrylic resin (“Mw” in Table 1)—

[0327] The weight average molecular weight of each acrylic resin was measured using high-performance liquid chromatography (HPLC) (product name: "HLC-8220GPC", manufactured by Tosoh Corporation).

[0328] Three TSKgel SuperAWM-H (manufactured by Tosoh Corporation, 6.0 mm I.D. × 15 cm) were used as chromatographic columns, and N-methylpyrrolidone (supplemented with 10 mM LiBr) was used as the eluent. The conditions were as follows: the sample concentration was set to 0.1% by mass, the flow rate was set to 0.5 mL / min, the sample injection volume was set to 60 μl, the measurement temperature was set to 40°C, and detection was performed using a differential refractive index (RI) detector. The calibration curve was prepared using eight samples of "TSK Standard Polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000" and "n-propylbenzene" as standard samples.

[0329] -Glass transition temperature of acrylic resin ("Tg" in Table 1)-

[0330] The glass transition temperature of the acrylic resin was measured using a differential scanning calorimeter (DSC) (product name: "EXSTAR6220", manufactured by Seiko Nanotechnology Co., Ltd.).

[0331] [Table 1]

[0332]

[0333] Image recording was performed using the prepared first ink, second ink, and third ink.

[0334] In image recording A, image recording is performed using only the first ink. In image recording B, image recording is performed using the first ink and the third ink. In image recording C, image recording is performed using the first ink, the second ink, and the third ink.

[0335] (Image record A)

[0336] An inkjet recording apparatus (product name "CylinderJET", manufactured by TRITEK) and an inkjet head (product name "KM1800i", manufactured by Konica Minolta) were used to apply the first ink (cyan ink) to an acrylic substrate (manufactured by JAPAN ACRYACE CO., LTD.; Acryl). Specifically, the first ink was applied to a 7 cm × 5 cm rectangle at a drop volume of 10.5 pL (picoliter) and a resolution of 600 × 600 dpi (dots per inch), resulting in a 100% solid image with a thickness of 4 μm to 6 μm. After applying the first ink, the LED light source attached to the inkjet recording apparatus was used to expose the image at an exposure dose of 100 mJ / cm 2 ~1000mJ / cm 2Ultraviolet irradiation: As an LED light source, a UV-LED irradiator with a peak wavelength of 385 nm (product name "G4B", manufactured by Kyocera Corporation) was used.

[0337] During the image recording, the gap between the acrylic substrate surface and the inkjet head was adjusted to 0.5 mm to 1 mm, and the ejection voltage was adjusted to a velocity of 7 m / s to 9 m / s.

[0338] (Image record B)

[0339] The third ink (primer) was applied to the main body of a PET bottle (product name "PET500 pill", manufactured by KOKUGO) using an inkjet recording device (product name "CylinderJET", manufactured by TRITEK) and an inkjet head (product name "KM1800i", manufactured by Konica Minolta). Specifically, the third ink was applied to a surface measuring 7 cm in the longitudinal direction and 5 cm in the circumferential direction of the PET bottle at a drop amount of 10.5 pL (picoliter) and a resolution of 600×600 dpi (dots per inch), recording a 100% solid image with a thickness of 4μm to 6μm. Furthermore, the first ink (cyan ink) was applied to the surface applied with the third ink under the same conditions as the application of the third ink, recording a 100% solid image with a thickness of 4μm to 6μm. After applying the third ink and after applying the first ink, the LED light source attached to the inkjet recording device was used to expose the image at an exposure of 10mJ / cm 2 ~100mJ / cm 2 Ultraviolet irradiation: As an LED light source, a UV-LED irradiator with a peak wavelength of 385 nm (product name "G4B", manufactured by Kyocera Corporation) was used.

[0340] The PET bottle with the image recorded on it was then placed in an exposure machine. The bottle was placed horizontally. The exposure machine was capable of rotating the bottle. While rotating the entire PET bottle, the image recorded on it was exposed using an LED light source. The exposure dose was 50 mJ / cm 2 ~500mJ / cm 2 The third ink and the first ink are completely cured by irradiation with ultraviolet rays, thereby obtaining an image recorded material.

[0341] During the image recording process, the gap between the PET bottle surface and the inkjet head was adjusted to 0.5 mm to 1 mm, and the ejection voltage was adjusted to a velocity of 7 m / s to 9 m / s.

[0342] (Image Record C)

[0343] Using an inkjet recording device (product name "CylinderJET", manufactured by TRITEK) and an inkjet head (product name "KM1800i", manufactured by Konica Minolta), a third ink (primer) was applied to the body of a PET bottle (product name "PET500 Pill", manufactured by KOKUGO). Specifically, the third ink was applied to a surface measuring 7 cm in the longitudinal direction and 5 cm in the circumferential direction of the PET bottle at a drop size of 10.5 pL (picoliters) and a resolution of 600 x 600 dpi (dots per inch), resulting in a 100% solid image with a thickness of 4 to 6 μm. Furthermore, the second ink (white ink) was applied to the surface coated with the third ink under the same conditions as the third ink application, resulting in a 100% solid image with a thickness of 4 to 6 μm. Furthermore, the first ink (cyan ink) was applied to the surface applied with the third ink and the second ink under the same conditions as the third ink, and a 100% solid image with a thickness of 4 to 6 μm was recorded. After applying the third ink, after applying the second ink, and after applying the first ink, the LED light source attached to the inkjet recording device was used to expose the image at an exposure dose of 10 mJ / cm 2 ~100mJ / cm 2 Ultraviolet irradiation: As an LED light source, a UV-LED irradiator with a peak wavelength of 385 nm (product name "G4B", manufactured by Kyocera Corporation) was used.

[0344] The PET bottle with the image recorded on it was then placed in an exposure machine. The bottle was placed horizontally. The exposure machine was capable of rotating the bottle. While rotating the entire PET bottle, the image recorded on it was exposed using an LED light source. The exposure dose was 50 mJ / cm 2 ~500mJ / cm 2 The third ink, the second ink, and the first ink are completely cured by irradiation with ultraviolet rays, thereby obtaining an image recorded material.

[0345] During the image recording process, the gap between the PET bottle surface and the inkjet head was adjusted to 0.5 mm to 1 mm, and the ejection voltage was adjusted to a velocity of 7 m / s to 9 m / s.

[0346] [evaluate]

[0347] For each of the Examples and Comparative Examples, the image records obtained in Image Recording A, Image Recording B, and Image Recording C were evaluated for scratch resistance, separation resistance, water resistance, and odor. Furthermore, the ejection properties of the first ink and the second ink were evaluated.

[0348] Tables 2 to 9 describe, as Evaluation 1, the evaluation results of the scratch resistance, separation resistance, water resistance, and odor of the image recorded material obtained in Image Recording A, and the evaluation results of the ejection properties of the first ink.

[0349] Tables 2 to 9 show, as Evaluation 2, the evaluation results of the scratch resistance, separation resistance, water resistance, and odor of the image recorded materials obtained in Image Recording B.

[0350] Tables 2 to 9 describe, as Evaluation 3, the evaluation results of the scratch resistance, separation resistance, water resistance, and odor of the image recorded materials obtained in Image Recording C, and the evaluation results of the ejection properties of the second ink.

[0351] The evaluation method is as follows.

[0352] <Separability (Image Recorded Material Obtained in Image Recording A)>

[0353] Twenty samples of the obtained image recorded material cut into 0.5 cm x 0.5 cm squares were prepared and each sample was stirred in a 1.5 mass % sodium hydroxide aqueous solution at 85°C.

[0354] At this time, the image recorded material obtained in image recording A was stirred for 30 minutes, and the image recorded material obtained in image recording B or image recording C was stirred for 10 minutes.

[0355] The samples were then allowed to stand for 10 minutes, and the ink film floating on the surface was recovered. The samples precipitated in the sodium hydroxide aqueous solution were washed with water and dried in a thermostatic bath at 30°C for 12 hours. After drying, the condition of each sample was visually inspected.

[0356] For each sample from which the ink film was completely peeled off, 5 points were added.

[0357] For each sample that had a portion of the ink film peeled off, 2 points were added.

[0358] For each sample where the ink film was not peeled off at all, 5 points were deducted.

[0359] The 20 samples were scored according to the above criteria, and the separability was evaluated based on the total score. The evaluation criteria are as follows.

[0360] 5: The total score is 91 to 100 points.

[0361] 4: The total score is 81 to 90 points.

[0362] 3: The total score is 51 to 80 points.

[0363] 2: The total score is 10 to 50 points.

[0364] 1: Total score is 9 or less.

[0365] <Scratch resistance>

[0366] A white cotton cloth for friction is attached to the front end of the friction member, and the image recording surface of the image recording material is repeatedly rubbed 100 times in a weightless state using a Gakushin type friction fastness tester (product name "AB-301", manufactured by TESTER SANGYO Co., Ltd.). The contamination of the white cotton cloth and the discoloration of the image recording material are evaluated using the contamination grayscale. The white cotton cloth for friction is a 100% cotton fine cotton cloth No. 3. The contamination of the white cotton cloth and the discoloration of the image recording material are evaluated according to the dry friction fastness evaluation criteria below. The contamination grayscale is based on JIS L 0805 (2005) and is expressed in nine levels: level 1, level 1-2, level 2, level 2-3, level 3, level 3-4, level 4, level 4-5, and level 5.

[0367] 5: Level 5

[0368] 4: Level 4-5

[0369] Level 3:4

[0370] 2: Level 2-3, Level 3, Level 3-4,

[0371] 1: Level 1, Level 1-2, Level 2

[0372] Water resistance

[0373] The resulting image recorded material was immersed in ion-exchanged water at 10°C to 25°C. After 24 hours, the image recorded material was removed from the ion-exchanged water. The image-recorded surface of the removed image recorded material was scratched with a pencil (hardness H) and visually inspected to see if the image peeled off. If the image peeled off, the image recorded material was immersed in ion-exchanged water again, removed after 24 hours, and the image surface of the image recorded material was scratched with a pencil (hardness H).

[0374] This operation is performed up to 9 times. If peeling of the image occurs, the next operation is not performed. The evaluation criteria are as follows. Level 3 or above is a level that is not a problem in practical use.

[0375] 5: After 8 operations, no peeling of the image occurred.

[0376] 4: After 8 operations, image peeling occurred.

[0377] 3: After 7 operations, image peeling occurred.

[0378] 2: After 6 operations, image peeling occurred.

[0379] 1: Image peeling occurred after 5 or fewer operations.

[0380] <Smell>

[0381] Cut a 10 cm x 10 cm image sample from the resulting image record. Within 10 minutes after image recording, place the image sample in a 500 mL wide-mouthed glass bottle, tightly seal it, and let it sit for three days. After three days, sensory evaluation of the odor was conducted. Ten panelists rated the odor based on the total score, with "no odor" receiving 50 points, "very slight odor" receiving 47 points, "slight odor" receiving 30 points, "clear odor" receiving 20 points, and "strong odor" receiving 0 points. The evaluation criteria are as follows. A rating of 3 or higher indicates no practical problems.

[0382] 5: 495 points or above

[0383] 4: 485 points or higher but lower than 495 points

[0384] 3: 470 points or more and less than 485 points

[0385] 2: 450 points or more and less than 470 points

[0386] 1: Less than 450 points

[0387] <Ejection>

[0388] The ejection properties of the first ink or the second ink were evaluated using an inkjet recording apparatus (product name "CylinderJET", manufactured by TRITEK) and an inkjet head (product name "KM1800i", manufactured by Konica Minolta Inc.). The number of ejection nozzles before image recording was counted using a nozzle check pattern. Furthermore, after 10 minutes of image recording, the number of ejection nozzles after image recording was counted using a nozzle check pattern.

[0389] The number of ejection nozzles before and after image recording was used to calculate the reduction in the number of ejection nozzles. The same test was performed three times, and the ejection performance was evaluated based on the average value N of the reduction in the number of ejection nozzles. The evaluation criteria are as follows.

[0390] Reduction in the number of ejection nozzles = Number of ejection nozzles before image recording - Number of ejection nozzles after image recording

[0391] 5: N is less than 1.

[0392] 4: N is greater than or equal to 1 and less than 3.

[0393] 3: N is 3 or more and less than 4.

[0394] 2: N is greater than or equal to 4 and less than 7.

[0395] 1: N is 7 or greater.

[0396] Tables 2 to 9 show the evaluation results.

[0397] In Tables 2 to 9, "Ms / Mc" represents the mass ratio of the content of the silicone-based surfactant having a (meth)acryloyl group to the content of the acrylic resin.

[0398] [Table 2]

[0399]

[0400] [Table 3]

[0401]

[0402] [Table 4]

[0403]

[0404] [Table 5]

[0405]

[0406] [Table 6]

[0407]

[0408] [Table 7]

[0409]

[0410] [Table 8]

[0411]

[0412] [Table 9]

[0413]

[0414] As shown in Tables 2 to 9, Examples 1 to 34 contain a bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms, a silicone surfactant having a (meth)acryloyl group, a colorant, and an acrylic resin having a glass transition temperature of 30°C or higher, and the content of the bifunctional (meth)acrylate is 20% by mass or higher relative to the total amount of the active energy ray-curable inkjet ink. Therefore, the resulting image recorded materials have excellent abrasion resistance and releasability.

[0415] On the other hand, in Comparative Example 1, since no acrylic resin having a glass transition temperature of 30° C. or higher is contained, it is found that the scratch resistance is poor.

[0416] In Comparative Example 2, since the silicone-based surfactant having a (meth)acryloyl group was not contained, it was found that the separability was poor.

[0417] In Comparative Example 3, it was found that the scratch resistance was poor because the glass transition temperature of the acrylic resin was lower than 30°C.

[0418] Comparative Example 4 shows that the scratch resistance is poor because the bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms is not contained.

[0419] In Comparative Example 5, since the bifunctional (meth)acrylate having a linear or branched alkylene group having 4 to 10 carbon atoms was not contained, the ink could not be ejected, and an image recorded material could not be obtained.

[0420] In Example 1, it is found that the mass ratio of the content of the silicone-based surfactant having a (meth)acryloyl group to the content of the acrylic resin in the first ink is 4 or more, and therefore the ejection property is superior to that of Example 5.

[0421] In Example 1, the mass ratio of the content of the silicone surfactant having a (meth)acryloyl group to the content of the acrylic resin in the first ink is 7 or less, and therefore the scratch resistance is superior to that of Example 4.

[0422] In Example 29, the mass ratio of the polysiloxane structure content to the polyether structure content of the silicone surfactant having a (meth)acryloyl group contained in the first ink is 0.5 or more, and therefore, the separability is excellent compared to Examples 30 and 31.

[0423] In Example 8, it is found that the weight average molecular weight of the acrylic resin contained in the first ink is 5,000 to 100,000, and therefore the scratch resistance is excellent compared to Examples 12 and 13.

[0424] <Example 101>

[0425] A first ink C1 (cyan ink), a first ink M1 (magenta ink), a first ink Y1 (yellow ink), a first ink K1 (black ink), a second ink W1 (white ink), and a third ink P1 (transparent ink) are prepared.

[0426] As the first ink C1, the first ink in Example 1 was used.

[0427] As the second ink W1, the second ink in Example 1 was used.

[0428] As the third ink P1, the third ink in Example 1 was used.

[0429] [Preparation of First Inks M1, Y1, and K1]

[0430] First, a magenta pigment dispersion, a yellow pigment dispersion, and a black pigment dispersion are prepared.

[0431] The magenta pigment dispersion, the yellow pigment dispersion, and the black pigment dispersion were prepared by replacing the cyan pigment with a magenta pigment, a yellow pigment, and a black pigment, respectively, in the preparation of the cyan pigment dispersion described above.

[0432] The details of the magenta pigment, the yellow pigment, and the black pigment are as follows.

[0433] Magenta pigment: CI Pigment RED 122, product name "TRM-33", manufactured by Dainichi Seika Co., Ltd.

[0434] Yellow pigment: CI Pigment Yellow 185, product name "Paliotol Yellow D 1155", manufactured by Sun Chemical (DIC)

[0435] Black pigment: Carbon black, product name "MOGUL E", manufactured by CABOT

[0436] Next, the prepared magenta pigment dispersion, yellow pigment dispersion, and black pigment dispersion were each mixed with the components listed in Table 10 so that the content of each component reached the content (mass %) listed in the table. The mixture was stirred at 25°C and 5000 rpm for 20 minutes using a mixer (product name "L4R", manufactured by Silverson) to obtain first inks M1, Y1, and K1.

[0437] [Table 10]

[0438]

[0439] [Image Record]

[0440] Using an inkjet recording device (product name "CylinderJET", manufactured by TRITEK) and an inkjet head (product name "KM1800i", manufactured by Konica Minolta), the third ink P1 was applied to the body of a PET bottle (product name "PET500 Pill", manufactured by KOKUGO). Specifically, the third ink P1 was applied at a drop size of 10.5 pL (picoliters) and a resolution of 600 x 600 dpi (dots per inch) to a surface measuring 7 cm in the longitudinal direction and 5 cm in the circumferential direction of the PET bottle, resulting in a 100% solid image with a thickness of 4 to 6 μm. Furthermore, the second ink W1, first ink K1, first ink C1, first ink M1, and first ink Y1 were applied in this order to the surface coated with third ink P1, using the same conditions as for applying third ink P1, resulting in a 100% solid image with a thickness of 4 to 6 μm.

[0441] After applying the third ink P1, the second ink W1, the first ink K1, the first ink C1, the first ink M1, and the first ink Y1, the LED light source attached to the inkjet recording device was used to expose the ink at an exposure of 10 mJ / cm 2 ~100mJ / cm 2 Ultraviolet irradiation: As an LED light source, a UV-LED irradiator with a peak wavelength of 385 nm (product name "G4B", manufactured by Kyocera Corporation) was used.

[0442] Next, the PET bottle with the image recorded on it was placed in an exposure machine. The PET bottle was placed horizontally. The exposure machine was capable of rotating the PET bottle. While rotating the entire image recorded on the PET bottle, the PET bottle was exposed using an LED light source. The exposure dose was 50 mJ / cm 2 ~500mJ / cm 2 The third ink P1 , the second ink W1 , the first ink K1 , the first ink C1 , the first ink M1 , and the first ink Y1 are completely cured by irradiation with ultraviolet rays, thereby obtaining an image recorded object.

[0443] During the image recording process, the gap between the PET bottle surface and the inkjet head was adjusted to 0.5 mm to 1 mm, and the ejection voltage was adjusted to a velocity of 7 m / s to 9 m / s.

[0444] The resulting image recorded material was evaluated for scratch resistance, separation resistance, water resistance, and odor using the same evaluation methods as in Example 1. Furthermore, the ejection properties of the first inks M1, Y1, and K1 were evaluated using the same evaluation methods as in Example 1. All evaluation results were "5."

[0445] In addition, the disclosure of Japanese Patent Application No. 2023-013499, filed on January 31, 2023, is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications, and technical specifications described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, or technical specification was specifically and individually indicated to be incorporated by reference.

Claims

1. An active energy ray-curable inkjet ink, wherein: It contains a bifunctional (meth)acrylate having a linear or branched alkylene group with 4 to 10 carbon atoms, a silicone surfactant having a (meth)acryloyl group, a colorant, and an acrylic resin having a glass transition temperature of 30° C. or higher. The content of the bifunctional (meth)acrylate is 20% by mass or more based on the total amount of the active energy ray-curable inkjet ink.

2. The active energy ray-curable inkjet ink according to claim 1, wherein The mass ratio of the content of the silicone-based surfactant having a (meth)acryloyl group to the content of the acrylic resin is 1 to 10.

3. The active energy ray-curable inkjet ink according to claim 1, wherein The mass ratio of the content of the silicone-based surfactant having a (meth)acryloyl group to the content of the acrylic resin is 4 to 7.

4. The active energy ray-curable inkjet ink according to claim 1, wherein The content of the silicone-based surfactant having a (meth)acryloyl group is 0.5% by mass to 10% by mass based on the total amount of the active energy ray-curable inkjet ink.

5. The active energy ray-curable inkjet ink according to claim 1, wherein The content of the silicone-based surfactant having a (meth)acryloyl group is 4% by mass to 7% by mass based on the total amount of the active energy ray-curable inkjet ink.

6. The active energy ray-curable inkjet ink according to claim 1, wherein The silicone surfactant having a (meth)acryloyl group contains a polyether structure and a polysiloxane structure. The mass ratio of the content of the polysiloxane structure to the content of the polyether structure is 0.5 or more. 7 . The active energy ray-curable inkjet ink according to claim 1 , further comprising a monofunctional (meth)acrylate having a hydroxyl group.

8. The active energy ray-curable inkjet ink according to claim 1, wherein The acrylic resin has a weight average molecular weight of 5,000 to 100,000.

9. An active energy ray-curable ink set, characterized in that: have: a first ink, wherein the first ink is the active energy ray-curable inkjet ink according to any one of claims 1 to 8, and the colorant is a pigment other than a white pigment; and The second ink is the active energy ray-curable inkjet ink according to any one of claims 1 to 8, and the colorant is a white pigment.

10. The active energy ray-curable ink set according to claim 9, wherein: When the first ink and the second ink are set to the same mass, The content of the acrylic resin in the first ink is greater than the content of the acrylic resin in the second ink. 11 . The active energy ray-curable ink set according to claim 9 , further comprising a third ink containing at least one acid group-containing compound selected from the group consisting of a polymerizable monomer having an acid group and a polymer having an acid group.

12. The active energy ray-curable ink set according to claim 11, wherein: When the first ink, the second ink, and the third ink are set to the same mass, The content of the acrylic resin in the first ink is greater than the content of the acrylic resin in the second ink. The content of the acrylic resin in the first ink is greater than the content of the acrylic resin in the third ink.

13. An image recording method, wherein: It includes the following steps: imparting the active energy ray-curable inkjet ink according to any one of claims 1 to 8 to a substrate by inkjet recording; and The applied active energy ray-curable inkjet ink is irradiated with active energy rays.

14. An image recording method, wherein: The active energy ray-curable ink set according to claim 9 is used. That The process includes the following steps: applying the second ink on the substrate by inkjet recording; irradiating the applied second ink with active energy rays; applying the first ink to the substrate provided with the second ink by inkjet recording; as well as The applied first ink is irradiated with active energy rays.

Images