Inkjet ink set for non-permeable substrate, image recording method, image recorded material, laminate, and method for manufacturing laminate

Abstract

Provided are an inkjet ink set for an impermeable substrate and applications thereof, the inkjet ink set comprising: a pretreatment liquid containing a resin and water; and an ink containing a pigment, a resin, and water, wherein the equilibrium moisture content of the solid content of the pretreatment liquid at 25ºC and 50% RH is at most 3.0 mass%, and the equilibrium moisture content of the solid content of the ink at 25ºC and 50% RH is at most 3.0 mass%.

Description

[Technical Field]

[0001] The present disclosure relates to an inkjet ink set for non-permeable substrates, an image recording method, an image recorded product, a laminate, and a method for manufacturing a laminate. [Background technology]

[0002] Conventionally, various studies have been conducted on image recording using a pretreatment liquid and ink.

[0003] For example, Japanese Patent Application Laid-Open No. 2016-203470 describes an ink set that includes at least an ink composition containing a resin with a water absorption rate of 0.3% or less and water, and a reaction liquid containing an aggregating agent that aggregates the components of the ink composition and has a solubility of 120 g or less in 100 g of water, and that is used for recording on low-absorbency recording media or non-absorbency recording media. Summary of the Invention [Problem to be solved by the invention]

[0004] After an image is recorded on an impermeable substrate to obtain an image recorded product, a laminate may be produced by laminating a substrate for lamination onto the image on the image recorded product. When the laminated product is subjected to a boiling treatment, it may be required to improve the lamination strength between the image recorded product and the substrate for lamination.

[0005] The present disclosure has been made in consideration of the above circumstances, and one embodiment of the present disclosure provides an inkjet ink set for non-permeable substrates and an image recording method that are capable of producing a laminate by laminating a laminating substrate onto an image recorded material, and of obtaining an image recorded material that has excellent lamination strength when the laminated material is subjected to a boiling treatment. According to another embodiment of the present disclosure, there is provided a method for producing a laminated body that, when subjected to boiling treatment, can produce a laminated body that has excellent lamination strength between the lamination substrate and the image recording material. According to another embodiment of the present disclosure, an image-recorded product is provided that exhibits excellent lamination strength when the laminate is subjected to a boiling treatment. Another problem to be solved by another embodiment of the present disclosure is to provide a laminated body that has excellent lamination strength between a lamination substrate and an image recorded material when subjected to boiling treatment. [Means for solving the problem]

[0006] The present disclosure includes the following aspects. <1> An inkjet ink set for non-permeable substrates, comprising: a pretreatment liquid containing a resin and water; and ink containing a pigment, a resin, and water, wherein the equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH is 3.0% by mass or less, and the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH is 3.0% by mass or less. <2> The equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH is lower than the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH. <1> 10. An inkjet ink set for non-permeable substrates according to claim 19. <3> The resin contained in the ink contains resin particles. <1> or <2> 10. An inkjet ink set for non-permeable substrates according to claim 19. <4> The resin contained in the ink includes resin particles having an acid value of less than 30 mgKOH / g and resin particles having an acid value of 30 mgKOH / g or more. <1> ~ <3> 10. An inkjet ink set for non-permeable substrates according to any one of the preceding items. <5> the mass ratio of the content of resin particles having an acid value of less than 30 mgKOH / g to the content of resin particles having an acid value of 30 mgKOH / g or more is 1.5 to 4.0; <4> 10. An inkjet ink set for non-permeable substrates according to claim 19. <6> The equilibrium moisture content of the ink solids at 25°C and 50% RH is 1.5% by mass or less. <1> ~ <5> 10. An inkjet ink set for non-permeable substrates according to any one of the preceding items. <7> The equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH is 1.5% by mass or less. <1> ~ <6> 10. An inkjet ink set for non-permeable substrates according to any one of the preceding items. <8> The resin contained in the pretreatment liquid and the resin contained in the ink are acrylic resin or urethane resin, respectively. <1> ~ <7> 10. An inkjet ink set for non-permeable substrates according to any one of the preceding items. <9> <1> ~ <8> 1. An image recording method comprising the steps of: applying a pretreatment liquid onto a non-permeable substrate; and applying ink, by an inkjet recording method, onto the non-permeable substrate to which the pretreatment liquid has been applied, wherein the inkjet ink set for non-permeable substrates described in any one of 1 to 3 above is used. <10> <9> and laminating a substrate for lamination onto the side of the image recorded item on which the image is disposed to obtain a laminated item. <11> An image recording material comprising: an impermeable substrate; and an image disposed on the impermeable substrate, the image including: a pretreatment layer disposed on the impermeable substrate and containing a resin; and an ink layer disposed on the pretreatment layer and containing a pigment and a resin, wherein the equilibrium moisture content of the pretreatment layer at 25°C and 50% RH is 3.0% by mass or less, and the equilibrium moisture content of the ink layer at 25°C and 50% RH is 3.0% by mass or less. <12> <11> and a lamination substrate laminated on the image of the image recorded material. A laminate body comprising: [Effects of the Invention]

[0007] According to one embodiment of the present disclosure, there are provided an inkjet ink set for non-permeable substrates and an image recording method that can produce a laminate by laminating a laminating substrate onto an image recorded material, and that can obtain an image recorded material that has excellent lamination strength when the laminated material is subjected to a boiling treatment. According to another embodiment of the present disclosure, there is provided a method for producing a laminated body that, when subjected to boiling treatment, can produce a laminated body that has excellent lamination strength between the lamination substrate and the image recording material. According to another embodiment of the present disclosure, an image-recorded product is provided that exhibits excellent lamination strength when the laminate is subjected to a boiling treatment. According to another embodiment of the present disclosure, a laminated body is provided that exhibits excellent lamination strength between the lamination substrate and the image recorded material when subjected to boiling treatment. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining details of the evaluation criteria for character quality in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The inkjet ink set for non-permeable substrates, the image recording method, and the method for producing a laminate according to the present disclosure will be described in detail below.

[0010] In this specification, a numerical range indicated using "to" means a range that includes the numerical values before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0011] In this specification, the amount of each component in a composition means the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition. As used herein, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0012] In this specification, the term "image" refers to a film formed by applying a pretreatment liquid and an ink in this order, and the term "image recording" refers to the formation of an image (that is, a film). Additionally, the concept of "image" in this specification also includes a solid image.

[0013] In this specification, the term "(meth)acrylate" encompasses both acrylate and methacrylate, and the term "(meth)acrylic" encompasses both acrylic and methacrylic.

[0014] In this specification, the term "boiling treatment" refers to a treatment in which an object (specifically, a laminate) is immersed in water at 60 to 100°C and heated for a certain period of time (for example, 10 to 120 minutes).

[0015] [Inkjet ink set for non-porous substrates] The inkjet ink set for non-permeable substrates according to the present disclosure (hereinafter also simply referred to as "the ink set of the present disclosure") comprises a pretreatment liquid containing a resin and water, and ink containing a pigment, a resin, and water, wherein the equilibrium water content of the solids of the pretreatment liquid at 25°C and 50% RH is 3.0% by mass or less, and the equilibrium water content of the solids of the ink at 25°C and 50% RH is 3.0% by mass or less.

[0016] According to the ink set of the present disclosure, an image recording material is obtained that comprises a non-permeable substrate and an image recorded on the non-permeable substrate, and a laminate is produced by laminating a laminating substrate onto the image, and even when the laminate is subjected to a boiling treatment, an image recording material with excellent lamination strength is obtained. Here, the lamination strength refers to the peel strength when peeling the laminate substrate and the image recording material in a laminated body formed by the above lamination (i.e., a laminated body having a layered structure of "lamination substrate / image recording material" (more specifically, a layered structure of "lamination substrate / image / non-permeable substrate").

[0017] The reason why the ink set of the present disclosure exhibits the above-mentioned effects is presumed to be as follows. In order to improve the lamination strength of the laminate, it is necessary to first improve the adhesion between the non-permeable substrate and the image, and then to improve the adhesion between the image and the substrate for lamination.

[0018] In the ink set of the present disclosure, the equilibrium moisture content of the solids of the pretreatment liquid is 3.0% by mass or less at 25°C (temperature) and 50% RH (relative humidity), and the equilibrium moisture content of the solids of the ink is 3.0% by mass or less at 25°C (temperature) and 50% RH (relative humidity). This improves adhesion between the pretreatment layer formed by applying the pretreatment liquid and the ink layer formed by applying the ink, suppresses internal expansion of the ink layer, and improves adhesion between the ink layer and the lamination substrate, which is presumably why lamination strength after boiling is improved.

[0019] On the other hand, in the ink set disclosed in Patent Document 1, the pretreatment liquid does not contain a resin, which is thought to result in poor adhesion between the pretreatment layer and the ink layer and insufficient laminate strength after boiling. Furthermore, in conventional ink sets containing a pretreatment liquid and an ink, no attention has been paid to the equilibrium moisture content of the pretreatment liquid and the ink at 25°C and 50% RH.

[0020] Hereinafter, each component contained in the pretreatment liquid and ink of the ink set of the present disclosure will be described.

[0021] [Ink set] <Ink> The inks in the ink set of the present disclosure contain a pigment, a resin, and water.

[0022] (pigment) The inks included in the ink set of the present disclosure contain a pigment. The pigments contained in the inks may be one type or two or more types.

[0023] The pigment may be either an organic pigment or an inorganic pigment that is normally commercially available. Examples of the pigment include those described in "Pigment Dictionary" edited by Seijiro Ito (published in 2000), "Industrial Organic Pigments" by W. Herbst and K. Hunger, and JP-A Nos. 2002-12607, 2002-188025, 2003-26978, and 2003-342503.

[0024] The pigment may be a water-insoluble pigment that can be dispersed in water with the aid of a dispersant, or may be a self-dispersing pigment. A self-dispersing pigment is a pigment that can be dispersed in water without the aid of a dispersant. A self-dispersing pigment is a compound in which at least one hydrophilic group selected from the group consisting of a carbonyl group, a hydroxyl group, a carboxyl group, a sulfo group, a phosphate group, and salts thereof is chemically bonded to the surface of the pigment directly or via another group.

[0025] Examples of organic pigments include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Examples of azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Examples of dye chelates include basic dye chelates and acid dye chelates.

[0026] Examples of inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black.

[0027] From the viewpoints of image density and ink ejection properties, the content of the pigment in the ink is preferably 1% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 1% by mass to 10% by mass, based on the total amount of the ink.

[0028] (resin) The inks included in the ink set of the present disclosure contain a resin. The resin contained in the ink may be one type, or two or more types.

[0029] The resin contained in the ink may be a dispersant that functions to disperse the pigment contained in the ink, or may be a resin that is added to the ink separately from the dispersant. Therefore, the ink may contain only a resin that functions as a dispersant, or may contain a resin that functions as a dispersant and a resin other than the resin that functions as a dispersant. Furthermore, if the pigment contained in the ink is a self-dispersing pigment, the ink may contain only a resin other than the resin that functions as a dispersant.

[0030] The type of resin contained in the ink is not particularly limited, and examples thereof include acrylic resin, epoxy resin, urethane resin, polyether, polyamide, phenol resin, silicone resin, fluororesin, vinyl resin (e.g., vinyl chloride resin, vinyl acetate resin, vinyl alcohol resin, vinyl butyral resin), alkyd resin, polyester resin, melamine resin, melamine formaldehyde resin, aminoalkyd co-condensation resin, and urea resin. Of these, the resin contained in the ink is preferably an acrylic resin or a urethane resin, from the viewpoint of improving laminate strength and laminate strength after boiling treatment.

[0031] In the present disclosure, acrylic resin refers to a polymer containing structural units derived from a (meth)acrylic compound having an acryloyl group (CH2=CH-C(=O)-) or a methacryloyl group (CH2=C(CH3)-C(=O)-). Examples of (meth)acrylic compounds include (meth)acrylic acid, (meth)acrylic acid esters, and (meth)acrylamide. In acrylic resins, examples of structural units other than those derived from (meth)acrylic compounds include structural units derived from styrene. Styrene-acrylic resins are included in the acrylic resins.

[0032] In the present disclosure, a urethane resin refers to a polymer containing a urethane bond. The urethane resin is synthesized, for example, by reacting a diol compound with a diisocyanate compound. For details about the diol compound and the diisocyanate compound, reference can be made to the descriptions in paragraphs 0031 to 0036 of JP 2001-247787 A. Among these, the urethane resin is preferably a polyester-based urethane resin having an ester bond in the main chain, a polycarbonate-based urethane resin having a carbonate bond in the main chain, or a polyether-based urethane resin having an ether bond in the main chain, and more preferably a polycarbonate-based urethane resin.

[0033] From the viewpoint of ejection performance, the content of the resin in the ink is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, based on the total amount of the ink. The lower limit of the resin content is not particularly limited, and is, for example, 0.1% by mass.

[0034] -Resin that functions as a dispersant- The resin functioning as a dispersant is usually mixed with the pigment in advance and contained in the pigment dispersion. The resin functioning as a dispersant may be appropriately selected from conventionally known dispersants and may be a random copolymer or a block copolymer. Furthermore, the resin functioning as a dispersant may have a crosslinked structure.

[0035] The resin that functions as a dispersant is preferably a resin having a crosslinked structure (hereinafter also referred to as a "crosslinked resin"). That is, the ink included in the ink set of the present disclosure preferably contains a crosslinked resin. The crosslinked resin that functions as a dispersant can disperse the pigment in water by coating part of the pigment surface. The crosslinked resin is unlikely to detach from the pigment surface, allowing the pigment to be stably dispersed.

[0036] A crosslinked resin is formed by crosslinking a resin that has not been crosslinked (hereinafter also referred to as an "uncrosslinked resin").

[0037] The uncrosslinked resin is preferably water-soluble.

[0038] In the present disclosure, "water-soluble" means the property of dissolving 1 g or more in 100 g of water at 25° C. Preferably, "water-soluble" means the property of dissolving 3 g or more (more preferably 10 g or more) in 100 g of water at 25° C.

[0039] Even if the uncrosslinked resin is water-soluble, the crosslinked resin is not necessarily water-soluble.

[0040] Examples of the uncrosslinked resin include vinyl resin, acrylic resin, urethane resin, and polyester resin, and among these, the uncrosslinked resin is preferably an acrylic resin.

[0041] The uncrosslinked resin is preferably a polymer having a functional group that can be crosslinked by a crosslinking agent. Examples of the crosslinkable functional group include a carboxy group or a salt thereof, an isocyanate group, and an epoxy group. Among these, from the viewpoint of improving the dispersibility of the pigment, the crosslinkable functional group is preferably a carboxy group or a salt thereof, and a carboxy group is particularly preferred. That is, the uncrosslinked resin is preferably a polymer containing a carboxy group.

[0042] The uncrosslinked resin is preferably a copolymer containing a structural unit derived from a monomer containing a carboxy group (hereinafter referred to as a "carboxy group-containing monomer"). The structural unit derived from the carboxy group-containing monomer contained in the copolymer may be of only one type, or may be of two or more types. The copolymer may be a random copolymer or a block copolymer, but is preferably a random copolymer.

[0043] Examples of carboxy group-containing monomers include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid.

[0044] From the viewpoint of crosslinkability and dispersibility, the carboxy group-containing monomer is preferably (meth)acrylic acid or β-carboxyethyl acrylate, and more preferably (meth)acrylic acid.

[0045] The content of structural units derived from carboxy group-containing monomers is preferably 5% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, and even more preferably 10% by mass to 30% by mass, relative to the total amount of the uncrosslinked resin.

[0046] The uncrosslinked resin preferably contains a structural unit derived from a hydrophobic monomer in addition to a structural unit derived from a carboxyl group-containing monomer. The structural unit derived from a hydrophobic monomer contained in the copolymer may be of one type or two or more types.

[0047] Examples of hydrophobic monomers include (meth)acrylates having an alkyl group with 1 to 20 carbon atoms, (meth)acrylates having an aromatic ring (for example, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), styrene, and styrene derivatives.

[0048] The content of the structural unit derived from the hydrophobic monomer is preferably 60% by mass to 95% by mass, more preferably 65% by mass to 90% by mass, and even more preferably 70% by mass to 90% by mass, relative to the total amount of the uncrosslinked resin.

[0049] The uncrosslinked resin is preferably a random copolymer containing a structural unit derived from a carboxy group-containing monomer and at least one of a structural unit derived from a (meth)acrylate having an alkyl group with 1 to 20 carbon atoms and a structural unit derived from a (meth)acrylate having an aromatic ring, more preferably a random copolymer containing a structural unit derived from (meth)acrylic acid and a structural unit derived from a (meth)acrylate having an aromatic ring, and even more preferably a copolymer containing a structural unit derived from (meth)acrylic acid and a structural unit derived from benzyl (meth)acrylate.

[0050] The weight average molecular weight (Mw) of the uncrosslinked resin is not particularly limited, but from the viewpoint of dispersibility of the white pigment, it is preferably 3,000 to 300,000, more preferably 5,000 to 200,000, and even more preferably 7,000 to 100,000.

[0051] The preferred range of the weight average molecular weight of the crosslinked resin is the same as the preferred range of the weight average molecular weight of the uncrosslinked resin.

[0052] In this disclosure, the weight-average molecular weight (Mw) is measured by gel permeation chromatography (GPC). The GPC is performed using an HLC-8220GPC (manufactured by Tosoh Corporation) with three columns connected in series: TSKgel SuperHZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ2000 (all trade names of Tosoh Corporation). The eluent is tetrahydrofuran (THF). The conditions are a sample concentration of 0.45% by mass, a flow rate of 0.35 ml / min, a sample injection volume of 10 μl, and a measurement temperature of 40°C. A differential refractive index detector is used. In addition, the calibration curve is created from eight samples of "Standard sample TSK standard, polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0053] The crosslinking agent used to crosslink the uncrosslinked resin is preferably a compound having two or more reactive sites with the uncrosslinked resin (e.g., a polymer having a carboxy group). Only one type of crosslinking agent may be used, or two or more types may be used.

[0054] A preferred combination of a crosslinking agent and an uncrosslinked resin is a combination of a compound having two or more epoxy groups (i.e., a bifunctional or higher epoxy compound) and a polymer having a carboxy group. In this combination, a crosslinked structure is formed by the reaction between the epoxy group and the carboxy group. The formation of the crosslinked structure by the crosslinking agent is preferably carried out after the pigment is dispersed with the uncrosslinked resin.

[0055] Examples of difunctional or higher functional epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.

[0056] Among these, the difunctional or higher epoxy compound is preferably polyethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, or trimethylolpropane triglycidyl ether.

[0057] The crosslinking agent may be a commercially available product. Commercially available products include, for example, Denacol EX-321, EX-821, EX-830, EX-850 and EX-851 (manufactured by Nagase ChemteX Corporation).

[0058] The molar ratio of reactive sites (e.g., epoxy groups) in the crosslinking agent to reactive sites (e.g., carboxy groups) in the uncrosslinked resin is preferably 1:1.1 to 1:10, more preferably 1:1.1 to 1:5, and even more preferably 1:1.1 to 1:3, from the viewpoints of the crosslinking reaction rate and dispersion stability after crosslinking.

[0059] -Resins other than those that function as dispersants- The ink can be prepared, for example, by adding a resin other than the resin that functions as a dispersant to a pigment dispersion. Examples of the resin that is added later include a water-soluble resin and resin particles.

[0060] The water-soluble resin may be selected from the above-mentioned uncrosslinked resins that are water-soluble. Examples of the water-soluble resin include polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose derivatives, polyethylene glycol, and poly(meth)acrylonitrile. The term "water-soluble" is as defined above.

[0061] The resin contained in the ink in the ink set of the present disclosure preferably contains resin particles. When the ink contains resin particles, when the ink is applied to a non-permeable substrate to which a pretreatment liquid has been applied, the resin particles in the ink come into contact with the pretreatment liquid, causing the resin particles to aggregate or become unstable in dispersion, thereby thickening the ink. This suppresses impact interference and improves image quality. Furthermore, when the ink contains resin particles, the strength of the ink film is improved, and the lamination strength of the image recording material is improved. In particular, the resin contained in the ink preferably contains acrylic resin particles or urethane resin particles.

[0062] The resin particles may contain only one type of resin, or two or more types of resins. The resin contained in the resin particles is preferably a water-insoluble resin.

[0063] In the present disclosure, "water-insoluble" in a water-insoluble resin refers to a property in which the amount of the resin that dissolves in 100 g of water at 25°C is less than 1.0 g (more preferably less than 0.5 g).

[0064] The resin particles preferably include at least one of particles made of acrylic resin (hereinafter referred to as "acrylic resin particles") and particles made of urethane resin (hereinafter also referred to as "urethane resin particles"), and more preferably include acrylic resin particles.

[0065] The resin particles are preferably self-dispersing resin particles. Examples of self-dispersible resin particles include those described in paragraphs 0062 to 0076 of JP2016-188345A and paragraphs 0109 to 0140 of WO2013 / 180074A.

[0066] The resin contained in the resin particles preferably has an aliphatic ring or an aromatic ring, and more preferably has an aromatic ring.

[0067] The aliphatic ring is preferably an alicyclic hydrocarbon having 5 to 10 carbon atoms, and is preferably a cyclohexane ring structure, a dicyclopentanyl ring structure, a dicyclopentenyl ring, or an adamantane ring.

[0068] The aromatic ring is preferably a naphthalene ring or a benzene ring, more preferably a benzene ring.

[0069] The resin contained in the resin particles preferably has an ionic group, from the viewpoint of further improving the water dispersibility of the resin particles.

[0070] The ionic group may be an anionic group or a cationic group, but from the viewpoint of ease of introduction, an anionic group is preferred.

[0071] The anionic group is not particularly limited, but is preferably a carboxy group or a sulfo group, and more preferably a sulfo group.

[0072] The weight average molecular weight of the resin in the resin particles is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and even more preferably 5,000 to 100,000.

[0073] From the viewpoint of ejection stability, the average particle diameter of the resin particles is preferably 1 nm to 200 nm, more preferably 3 nm to 200 nm, and even more preferably 5 nm to 50 nm. The average particle diameter of the resin particles is determined by measuring the volume average particle diameter by dynamic light scattering using a particle size distribution measuring device, for example, a product name "Nanotrac UPA-EX150" manufactured by Nikkiso Co., Ltd.

[0074] The acid value of the resin particles contained in the ink is preferably 70 mgKOH / g or less, more preferably 30 mgKOH / g or less, and even more preferably 20 mgKOH / g. The lower limit of the acid value of the resin particles contained in the ink is not particularly limited and may be 0 mgKOH / g. The acid value of the resin particles contained in the ink is preferably 1 mgKOH / g or more, and more preferably 2 mgKOH / g or more.

[0075] From the viewpoint of improving image quality and lamination strength after boiling, the ink in the ink set of the present disclosure preferably contains two or more types of resin particles with different acid values. Specifically, the resin contained in the ink preferably contains resin particles with an acid value of less than 30 mgKOH / g (hereinafter simply referred to as "resin particles A") and resin particles with an acid value of 30 mgKOH / g or more (hereinafter simply referred to as "resin particles B"). Resin particles A and resin particles B may each be of one type, or two or more types.

[0076] From the viewpoint of improving the lamination strength after boiling treatment, the acid value of resin particles A is preferably 20 mgKOH / g or less, and more preferably 12 mgKOH / g or less. The lower limit of the acid value of resin particles A is, for example, 0 mgKOH / g. Furthermore, from the viewpoint of improving image quality, the acid value of resin particles B is preferably 45 mgKOH / g or more, and more preferably 60 mgKOH / g or more. The upper limit of the acid value of resin particles B is, for example, 100 mgKOH / g.

[0077] Furthermore, when two types of resin particles having different acid values are contained, it is preferable that the difference in acid value between the two types of resin particles be 30 or more, and it is more preferable that the difference in acid value between the two types of resin particles be 50 or more.

[0078] From the viewpoint of laminate strength, the mass ratio of the content of resin particles A to the content of resin particles B is preferably 1.0 to 6.0, more preferably 1.2 to 5.5, and even more preferably 1.5 to 4.0, and from the viewpoint of laminate strength and image quality, it is particularly preferably 2.0 to 4.0.

[0079] When the ink contains resin particles with an acid value of 30 mgKOH / g or more, the ink becomes more viscous when applied to an impermeable substrate to which a pretreatment liquid has been applied. This reduces landing interference and further improves image quality. In particular, when the mass ratio is 1.5 to 4.0, the laminate strength of the image-recorded product after boiling is improved and image quality is excellent.

[0080] In the present disclosure, the acid value is a value measured by the method described in JIS K0070:1992.

[0081] When the ink contains resin particles as the resin, the content of the resin particles is preferably 1% to 20% by mass, and more preferably 1% to 10% by mass, relative to the total amount of the ink.

[0082] (water) The ink in the ink set of the present disclosure contains water. The amount of water contained is not particularly limited, and is, for example, 40% to 70% by mass.

[0083] (organic solvent) The inks in the ink set of the present disclosure preferably contain an organic solvent. The organic solvent contained in the ink may be one type, or two or more types.

[0084] From the viewpoint of ejection stability and laminate strength, the organic solvent preferably contains an organic solvent having a boiling point of less than 200°C, and more preferably contains an organic solvent having a boiling point of 120 to 200°C.

[0085] The content of organic solvents with a boiling point of 200°C or higher is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 0% by mass, relative to the total amount of ink. In other words, it is preferable that the ink does not contain any organic solvents with a boiling point of 200°C or higher. If the ink contains an organic solvent, it is preferable that the organic solvent has a boiling point of less than 200°C.

[0086] When the content of the organic solvent having a boiling point of 200° C. or higher is 5% by mass or less, the lamination strength of the image recorded product and the lamination strength after boiling treatment are improved.

[0087] In the present disclosure, "boiling point" means the boiling point under 1 atmosphere (101,325 Pa). The boiling point is measured using a boiling point meter, for example, a boiling point measuring device (product name "DosaTherm300", manufactured by Titan Technologies).

[0088] Organic solvents with a boiling point of less than 200°C include: Alkylene glycols such as ethylene glycol (197°C) and propylene glycol (187°C); alkylene glycol alkyl ethers such as diethylene glycol monomethyl ether (194°C), diethylene glycol dimethyl ether (162°C), diethylene glycol ethyl methyl ether (176°C), diethylene glycol isopropyl methyl ether (179°C), propylene glycol monomethyl ether (121°C), propylene glycol monobutyl ether (170°C), propylene glycol monopropyl ether (150°C), 3-methoxy-3-methyl-1-butanol (174°C), propylene glycol monomethyl ether propionate (160°C), methyl cellosolve (ethylene glycol monomethyl ether, 125°C), ethyl cellosolve (ethylene glycol monoethyl ether, 135°C), butyl cellosolve (ethylene glycol monobutyl ether, 171°C), ethylene glycol mono-tert-butyl ether (153°C), and dipropylene glycol monomethyl ether (188°C); Esters such as ethylene glycol monomethyl ether acetate (145°C), ethyl acetate (154°C), ethyl lactate (154°C), 3-methoxybutyl acetate (172°C); and Examples of ketones include diacetone alcohol (169°C), cyclohexanone (156°C), and cyclopentanone (131°C). The numbers in parentheses indicate boiling points.

[0089] Examples of organic solvents having a boiling point of 200°C or higher include alcohols such as 1,3-butanediol (207°C), 1,4-butanediol (228°C), benzyl alcohol (205°C), and terpineol (217°C); Alkylene glycols such as diethylene glycol (244°C), triethylene glycol (287°C), and dipropylene glycol (230°C); Alkylene glycol alkyl ethers such as diethylene glycol monoethyl ether (202°C), diethylene glycol monobutyl ether (231°C), triethylene glycol monomethyl ether (249°C), triethylene glycol dimethyl ether (216°C), diethylene glycol monohexyl ether (261°C or higher), and tripropylene glycol monomethyl ether (243°C); and Examples include esters such as diethylene glycol monoethyl ether acetate (217°C). The numbers in parentheses indicate boiling points.

[0090] The content of the organic solvent in the ink is preferably 5% by mass to 40% by mass, and more preferably 10% by mass to 30% by mass, relative to the total amount of the ink.

[0091] (additives) The ink may contain additives such as surfactants, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, and basic compounds, as needed.

[0092] (Physical Properties) The equilibrium moisture content of the ink solids at 25°C and 50% RH is 3.0% by mass or less, preferably 2.0% by mass or less, and more preferably 1.5% by mass or less. The lower limit of the equilibrium moisture content is not particularly limited, and is, for example, 0.1% by mass. The equilibrium moisture content is measured by the following method.

[0093] The ink was left in a constant temperature bath at 60°C for 24 hours. It was then vacuum dried at 60°C for 3 hours using a vacuum constant temperature dryer (product name "DRV420DA" manufactured by Advantec Co., Ltd.) to obtain the ink solid (solid content). The ink solid was then left in a constant temperature bath at 25°C and 50% RH for 24 hours. After 24 hours, the moisture content of the ink solid was measured by the moisture vaporization method using a trace moisture analyzer (product name "CA-200" manufactured by Mitsubishi Chemical Analytical Co., Ltd.). The moisture vaporization temperature was set to 140°C, and a coulometric titration reagent (product name "Aquamicron AKX" manufactured by Mitsubishi Chemical Co., Ltd.) was used as the anolyte, and a coulometric titration reagent (product name "Aquamicron CxU" manufactured by Mitsubishi Chemical Co., Ltd.) was used as the catholyte.

[0094] The solid matter of the ink may contain organic solvent depending on the boiling point of the organic solvent contained in the ink.

[0095] From the viewpoint of improving ejection stability, the pH of the ink is preferably 7 to 10, and more preferably 7.5 to 9.5. The pH is measured at 25°C using a pH meter, for example, a pH meter manufactured by Toa DKK Corporation (model number "HM-31")

[0096] The viscosity of the ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, preferably 2 mPa·s to 15 mPa·s, and even more preferably 3 mPa·s to 10 mPa·s. The viscosity is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0097] 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 30 mN / m to 45 mN / m. The surface tension is measured at 25°C using a surface tensiometer, for example, an automatic surface tensiometer (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., by the plate method.

[0098] <Pretreatment liquid> The pretreatment liquid in the ink set of the present disclosure contains a resin and water.

[0099] (resin) The pretreatment liquid contained in the ink set of the present disclosure contains a resin. The resin contained in the pretreatment liquid may be one type or two or more types.

[0100] The type of resin contained in the pretreatment liquid is not particularly limited, and examples thereof include the same resins as those exemplified as the resins contained in the ink. Among these, the resin contained in the pretreatment liquid is preferably an acrylic resin or a urethane resin, from the viewpoint of improving laminate strength.

[0101] In particular, from the perspective of further improving the laminate strength, it is preferable that the resin contained in the pretreatment liquid and the resin contained in the ink are both acrylic resin or urethane resin.

[0102] The resin contained in the pretreatment liquid may be the same as or different from the resin contained in the ink.

[0103] The resin content in the pretreatment liquid is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total amount of the pretreatment liquid. The lower limit of the resin content is not particularly limited, and is, for example, 0.1% by mass.

[0104] Examples of the resin include a water-soluble resin and resin particles.

[0105] Examples of the water-soluble resin include the same water-soluble resins as those explained in the ink section above.

[0106] From the perspective of improving image quality (particularly character quality), the resin contained in the pretreatment liquid in the ink set of the present disclosure preferably contains resin particles.

[0107] The resin particles may contain only one type of resin, or two or more types of resins. The resin contained in the resin particles is preferably a water-insoluble resin.

[0108] The resin particles preferably contain at least one of acrylic resin particles and urethane resin particles, and more preferably contain acrylic resin particles.

[0109] The resin particles are preferably self-dispersing resin particles. Examples of self-dispersible resin particles include those described in paragraphs 0062 to 0076 of JP2016-188345A and paragraphs 0109 to 0140 of WO2013 / 180074A.

[0110] The resin contained in the resin particles preferably has an aliphatic ring or an aromatic ring, and more preferably has an aromatic ring.

[0111] The aliphatic ring is preferably an alicyclic hydrocarbon having 5 to 10 carbon atoms, and is preferably a cyclohexane ring structure, a dicyclopentanyl ring structure, a dicyclopentenyl ring, or an adamantane ring.

[0112] The aromatic ring is preferably a naphthalene ring or a benzene ring, more preferably a benzene ring.

[0113] The resin contained in the resin particles preferably has an ionic group, from the viewpoint of further improving the water dispersibility of the resin particles.

[0114] The ionic group may be an anionic group or a cationic group, but from the viewpoint of ease of introduction, an anionic group is preferred.

[0115] The anionic group is not particularly limited, but is preferably a carboxy group or a sulfo group, and more preferably a sulfo group.

[0116] The weight average molecular weight of the resin in the resin particles is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and even more preferably 5,000 to 100,000.

[0117] From the viewpoint of ejection stability when ejected using an inkjet recording method, the average particle diameter of the resin particles is preferably 1 nm to 200 nm, more preferably 3 nm to 200 nm, and even more preferably 5 nm to 50 nm. The average particle diameter of the resin particles is determined by measuring the volume average particle diameter by dynamic light scattering using a particle size distribution measuring device, for example, a product name "Nanotrac UPA-EX150" manufactured by Nikkiso Co., Ltd.

[0118] The acid value of the resin particles is preferably 30 mg / KOH or less, more preferably 15 mg / KOH or less. When the acid value is 30 mg / KOH or less, the laminate strength after boiling treatment is improved.

[0119] (flocculant) From the viewpoint of improving image quality (particularly character quality), the pretreatment liquid preferably contains a flocculant. The flocculant is not particularly limited as long as it is a component that aggregates the components in the ink. The flocculant is preferably at least one selected from the group consisting of polyvalent metal compounds, organic acids, metal complexes, and cationic polymers, and more preferably contains an organic acid.

[0120] -Polyvalent metal compounds- Polyvalent metal compounds include salts of alkaline earth metals from Group 2 of the periodic table (e.g., magnesium, calcium), transition metals from Group 3 of the periodic table (e.g., lanthanum), metals from Group 13 of the periodic table (e.g., aluminum), and lanthanides (e.g., neodymium).

[0121] The salts of these metals are preferably salts of organic acids, nitrates, chlorides, or thiocyanates, as described below.

[0122] Among these, the polyvalent metal compound is preferably a calcium salt or magnesium salt of an organic acid (e.g., formic acid, acetic acid, benzoic acid, etc.); a calcium salt or magnesium salt of nitric acid; calcium chloride, magnesium chloride, or a calcium salt or magnesium salt of thiocyanic acid.

[0123] It is preferable that the polyvalent metal compound is at least partially dissociated into polyvalent metal ions and counter ions in the pretreatment liquid.

[0124] -Organic acid- The organic acid includes an organic compound having an acidic group.

[0125] Acidic groups include phosphate groups, phosphonate groups, phosphinate groups, sulfate groups, sulfonate groups, sulfinate groups, and carboxy groups.

[0126] Among these, from the viewpoint of the aggregation speed of the ink, the acidic group is preferably a phosphate group or a carboxy group, and more preferably a carboxy group.

[0127] It is preferable that at least a portion of the acidic groups is dissociated in the pretreatment liquid.

[0128] Examples of organic compounds having a carboxy group include (meth)acrylic acid, poly(meth)acrylic acid, acetic acid, formic acid, benzoic acid, glycolic acid, malonic acid, malic acid (preferably DL-malic acid), maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, citric acid, tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, and nicotinic acid.

[0129] Among these, from the viewpoint of the aggregation speed of the ink, the organic compound having a carboxy group is preferably a divalent or higher carboxylic acid (hereinafter also referred to as a polycarboxylic acid), and more preferably a dicarboxylic acid.

[0130] Specifically, the polycarboxylic acid is preferably malonic acid, malic acid, maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, tartaric acid, 4-methylphthalic acid, or citric acid, and more preferably malonic acid, malic acid, tartaric acid, succinic acid, glutaric acid, pimelic acid, adipic acid, or citric acid.

[0131] The organic acid preferably has a low pKa (for example, 1.0 to 5.0), which reduces the surface charge of particles such as pigments and resin particles in the ink, which are stabilized by weakly acidic functional groups such as carboxyl groups, by contacting them with an organic acid having a lower pKa, thereby reducing dispersion stability.

[0132] The organic acid preferably has a low pKa, high solubility in water, and a valence of at least 2. Furthermore, it is more preferable that the organic acid have a high buffering capacity in a pH range lower than the pKa of the functional group (e.g., carboxy group) that stabilizes the dispersion of the particles in the ink.

[0133] -Metal complexes- The metal complex preferably contains, as a metal element, at least one selected from the group consisting of zirconium, aluminum, and titanium.

[0134] The metal complex is preferably a metal complex containing, as a ligand, at least one selected from the group consisting of acetate, acetylacetonate, methylacetoacetate, ethylacetoacetate, octylene glycolate, butoxyacetylacetonate, lactate, lactate ammonium salt, and triethanolamine.

[0135] The metal complex may be a commercially available product. Various organic ligands, particularly various polydentate ligands capable of forming metal chelate catalysts, are commercially available. Therefore, the metal complex may be a metal complex prepared by combining a commercially available organic ligand with a metal.

[0136] Examples of the metal complex include zirconium tetraacetylacetonate (e.g., "Orgatix ZC-150" manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium monoacetylacetonate (e.g., "Orgatix ZC-540" manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium bisacetylacetonate (e.g., "Orgatix ZC-550" manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium monoethylacetoacetate (e.g., "Orgatix ZC-560" manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium acetate (e.g., "Orgatix ZC-115" manufactured by Matsumoto Fine Chemical Co., Ltd.), and titanium diisopropoxybis(acetylacetonate) (e.g., "Orgatix ZC-150" manufactured by Matsumoto Fine Chemical Co., Ltd.). TC-100"), titanium tetraacetylacetonate (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix TC-401"), titanium dioctyloxybis(octylene glycolate) (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix TC-200"), titanium diisopropoxybis(ethyl acetoacetate) (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix TC-750"), zirconium tetraacetylacetonate (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix ZC-700"), zirconium tributoxymonoacetylacetonate (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix ZC-540"), zirconium monobutoxyacetylacetonate bis(ethyl acetoacetate) (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix ZC-570"), zirconium dibutoxy bis(ethylacetoacetate) (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix ZC-580"), aluminum trisacetylacetonate (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix AL-80"), titanium lactate ammonium salt (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix TC-300"), titanium lactate (e.g., Matsumoto Fine Chemical Co., Ltd.'s "Orgatix TC-310, 315"), titanium triethanolamine (Matsumoto Fine Chemical Co., Ltd.'s "OrgatixTC-400), and zirconyl chloride compounds (for example, Orgatix ZC-126 manufactured by Matsumoto Fine Chemical Co., Ltd.).

[0137] Among these, the metal complex is preferably titanium lactate ammonium salt (e.g., "Orgatix TC-300" manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium lactate (e.g., "Orgatix TC-310, 315" manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium triethanolamine (e.g., "Orgatix TC-400" manufactured by Matsumoto Fine Chemical Co., Ltd.), or zirconyl chloride compound (e.g., "Orgatix ZC-126" manufactured by Matsumoto Fine Chemical Co., Ltd.).

[0138] -Cationic polymer- The pretreatment liquid may also contain one or more cationic polymers as aggregating components. The cationic polymer is preferably a homopolymer of a cationic monomer having a primary, secondary, or tertiary amino group or a quaternary ammonium salt group, or a copolymer or condensation polymer of a cationic monomer and a non-cationic monomer. The cationic polymer may be used in the form of either a water-soluble polymer or water-dispersible latex particles. Examples of cationic polymers include polyvinylpyridine salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, polyvinylimidazoles, polyethyleneimines, polybiguanides, polyguanides, polyallylamine, and derivatives thereof.

[0139] The weight-average molecular weight of the cationic polymer is preferably small from the viewpoint of viscosity of the pretreatment liquid. When the pretreatment liquid is applied to a recording medium by an inkjet recording method, the weight-average molecular weight is preferably 1,000 to 500,000, more preferably 1,500 to 200,000, and even more preferably 2,000 to 100,000. A weight-average molecular weight of 1,000 or more is advantageous from the viewpoint of aggregation speed. A weight-average molecular weight of 500,000 or less is advantageous from the viewpoint of ejection reliability. However, this does not apply when the pretreatment liquid is applied to a recording medium by a method other than inkjet recording.

[0140] The pretreatment liquid may contain only one type of flocculant, or two or more types.

[0141] The content of the flocculant is preferably 0.1% by mass to 40% by mass, more preferably 0.1% by mass to 30% by mass, even more preferably 1% by mass to 20% by mass, and particularly preferably 1% by mass to 10% by mass, relative to the total amount of the pretreatment liquid.

[0142] (water) The pretreatment liquid in the ink set of the present disclosure preferably contains water. There are no particular restrictions on the amount of water contained, and it is, for example, 50% to 90% by mass.

[0143] (organic solvent) The pretreatment liquid in the ink set of the present disclosure preferably contains an organic solvent. The organic solvent contained in the pretreatment liquid may be one type, or two or more types.

[0144] From the viewpoint of ejection stability and laminate strength, the organic solvent preferably contains an organic solvent having a boiling point of less than 200°C, and more preferably contains an organic solvent having a boiling point of 120 to 200°C.

[0145] The content of organic solvents with a boiling point of 200°C or higher is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 0% by mass, relative to the total amount of the pre-treatment liquid. That is, it is preferable that the pre-treatment liquid does not contain any organic solvents with a boiling point of 200°C or higher. When the pre-treatment liquid contains an organic solvent, the organic solvent preferably has a boiling point of less than 200°C.

[0146] When the content of the organic solvent having a boiling point of 200° C. or higher is 5% by mass or less, the lamination strength of the image recorded material and the lamination strength of the image recorded material after boiling treatment are improved.

[0147] Examples of organic solvents having a boiling point of less than 200° C. include those exemplified in the organic solvents contained in the ink.

[0148] The content of the organic solvent in the pretreatment liquid is preferably 5% by mass to 40% by mass, and more preferably 10% by mass to 30% by mass, based on the total amount of the pretreatment liquid.

[0149] (Other ingredients) The pretreatment liquid may contain other components in addition to the resin, flocculant, and water, as needed. Examples of other components that may be contained in the pretreatment liquid include known additives such as surfactants, solid wetting agents, colloidal silica, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, antifungal agents, pH adjusters, viscosity adjusters, rust inhibitors, chelating agents, and water-soluble polymer compounds (e.g., the water-soluble polymer compounds described in paragraphs 0026 to 0080 of JP 2013-001854 A).

[0150] (Physical Properties) The equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH is 3.0% by mass or less, preferably 1.5% by mass or less, and more preferably 1.0% by mass or less. The lower limit of the pretreatment liquid is not particularly limited, and is, for example, 0.1% by mass. The equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH is measured in the same manner as the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH.

[0151] The equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH is preferably lower than the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH. It is believed that water is more likely to penetrate into the pretreatment layer from the non-permeable substrate side during boiling. Therefore, a lower equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH results in superior laminate strength after boiling. Furthermore, the absolute value of the difference between the equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH and the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH is preferably 0.3 to 2.0, more preferably 0.3 to 1.0, and even more preferably 0.5 to 0.7.

[0152] From the viewpoint of the ink aggregation rate, the pH of the pretreatment liquid is preferably 0.1 to 4.5, and more preferably 0.2 to 4.0. The pH is measured at 25°C using a pH meter, for example, a pH meter manufactured by Toa DKK Corporation (model number "HM-31")

[0153] From the viewpoint of the ink aggregation speed, the viscosity of the pretreatment liquid is preferably 0.5 mPa·s to 10 mPa·s, and more preferably 1 mPa·s to 5 mPa·s. The viscosity is a value measured at 25°C using a viscometer. The viscosity is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0154] The surface tension of the pretreatment liquid is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 30 mN / m to 45 mN / m. The surface tension is a value measured at a temperature of 25°C. The surface tension is measured at 25°C using a surface tensiometer, for example, an automatic surface tensiometer (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., by the plate method.

[0155] <Image recording method> The image recording method of the present disclosure includes a step of applying a pretreatment liquid onto a non-permeable substrate (hereinafter referred to as a "pretreatment liquid applying step"), and a step of applying an ink to the non-permeable substrate to which the pretreatment liquid has been applied, using an inkjet recording method, to record an image (hereinafter referred to as an "image recording step").

[0156] (Pretreatment liquid application step) In the pretreatment liquid application step, the pretreatment liquid is applied onto the non-permeable substrate.

[0157] -Non-permeable base material- In this disclosure, the term "impermeable" in an impermeable substrate refers to a property in which the water absorption rate is 2.5% or less over 24 hours as measured in accordance with ASTM D570-98(2018). Here, the unit of water absorption rate, "%", is based on mass. The water absorption rate is preferably 1.0% or less, and more preferably 0.5% or less.

[0158] Examples of materials for the impermeable substrate include glass, metals (e.g., aluminum, zinc, copper, etc.), and resins (e.g., polyvinyl chloride, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, nylon, acrylic resin, etc.).

[0159] The material of the impermeable substrate is preferably a resin. Among these, from the viewpoint of versatility, the material of the impermeable substrate is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0160] The impermeable substrate is preferably in the form of a sheet (film) or plate, and examples of such impermeable substrates include glass plates, metal plates, resin sheets (resin films), plastic-laminated paper, metal-laminated or metal-deposited paper, and metal-laminated or metal-deposited plastic sheets (plastic films).

[0161] Examples of impermeable resin substrates include resin sheets (resin films), and specific examples include flexible packaging materials for packaging foods and the like, and floor guide panels in mass retailers.

[0162] Examples of impermeable substrates include not only sheet-shaped (film-shaped) or plate-shaped impermeable substrates, but also textiles (woven fabrics) and nonwoven fabrics formed from impermeable fibers.

[0163] The thickness of the impermeable substrate is preferably 0.1 μm to 1,000 μm, more preferably 0.1 μm to 800 μm, and even more preferably 1 μm to 500 μm.

[0164] The non-permeable substrate may be subjected to a hydrophilization treatment. Examples of hydrophilization treatments include, but are not limited to, corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, light irradiation treatment (e.g., UV treatment), and flame treatment. Corona treatment can be performed using, for example, a Corona Master (product name "PS-10S", manufactured by Shinko Electric Meter Co., Ltd.). The conditions for the corona treatment may be appropriately selected depending on the type of non-permeable substrate, etc.

[0165] Before applying the pretreatment liquid, the non-permeable substrate may be heated. The heating temperature may be set appropriately depending on the type of non-permeable substrate, but the temperature of the non-permeable substrate is preferably 30°C to 70°C, and more preferably 30°C to 60°C.

[0166] -Method of applying pre-treatment liquid- The method for applying the pretreatment liquid is not particularly limited, and examples thereof include known methods such as a coating method, a dipping method, and an inkjet recording method.

[0167] Examples of the coating method include known coating methods using a bar coater, extrusion die coater, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, reverse roll coater, and the like.

[0168] There are no particular limitations on the ink ejection method used in inkjet recording, and any of the well-known methods may be used, such as a charge control method that uses electrostatic attraction to eject ink, a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink with it, thereby ejecting the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and uses the resulting pressure.

[0169] As an inkjet recording method, in particular, the method described in JP-A-54-59936 can be effectively used, in which ink subjected to the action of thermal energy undergoes a sudden change in volume, and the ink is ejected from the nozzles by the force caused by this state change. As an inkjet recording method, the method described in paragraphs 0093 to 0105 of JP-A-2003-306623 can also be used.

[0170] The application of the pretreatment liquid to the non-permeable substrate by inkjet recording is carried out by ejecting the pretreatment liquid from the nozzles of an inkjet head.

[0171] Inkjet head methods include the shuttle method, in which a short serial head is scanned across the width of the recording medium to perform printing, and the line method, which uses a line head in which printing elements are arranged to cover the entire area of one side of the recording medium.

[0172] The line method allows for image recording over the entire surface of a recording medium by scanning the recording medium in a direction intersecting the arrangement direction of the recording elements. The line method eliminates the need for a transport system, such as a carriage that scans a short head, as in the shuttle method. Furthermore, compared to the shuttle method, the line method does not require complex scanning control of the carriage movement and the recording medium, and only the recording medium moves. Therefore, the line method achieves faster image recording speeds than the shuttle method.

[0173] The pretreatment liquid is preferably applied using an inkjet head having a resolution of 300 dpi or more (more preferably 600 dpi or more, and even more preferably 800 dpi or more), where dpi stands for dots per inch, and 1 inch is 2.54 cm.

[0174] The amount of droplets of the pretreatment liquid ejected from the nozzles of the inkjet head is preferably 1 pL (picoliter) to 10 pL, and more preferably 1.5 pL to 6 pL, from the viewpoint of obtaining a high-definition image.

[0175] (Image recording process) In the image recording step, an ink is applied to the non-permeable substrate to which the pretreatment liquid has been applied, using an inkjet recording method to record an image. Details of the inkjet recording method are the same as those of the inkjet recording method in the method of applying the pretreatment liquid.

[0176] (Other processes) The image recording method of the present disclosure may include other steps in addition to the pretreatment liquid application step and the image recording step.

[0177] After the pretreatment liquid is applied to the non-permeable substrate, the pretreatment liquid may be dried by heating. Examples of means for drying the pretreatment liquid by heating include known heating means such as a heater, known air blowing means such as a dryer, and a combination of these.

[0178] Examples of methods for heating and drying the pretreatment liquid include a method of applying heat using a heater or the like from the side opposite to the surface of the non-permeable substrate to which the pretreatment liquid has been applied, a method of applying warm air or hot air to the surface of the non-permeable substrate to which the pretreatment liquid has been applied, a method of applying heat using an infrared heater from the side of the non-permeable substrate to which the pretreatment liquid has been applied or the side opposite to the surface to which the pretreatment liquid has been applied, and a combination of these methods.

[0179] The heating temperature during heat drying of the pretreatment liquid is preferably 35° C. or higher, and more preferably 40° C. or higher. There is no particular upper limit to the heating temperature, but it is preferably 100° C., more preferably 90° C., and even more preferably 70° C.

[0180] The heat drying time is not particularly limited, but is preferably 0.5 seconds to 60 seconds, more preferably 0.5 seconds to 20 seconds, and even more preferably 0.5 seconds to 10 seconds.

[0181] [Laminate manufacturing method] A method for manufacturing a laminated body, which is one embodiment of the present disclosure, includes a step of obtaining an image recorded matter comprising a non-permeable substrate and an image disposed on the non-permeable substrate by the image recording method of the present disclosure, and a step of laminating a laminating substrate to the side of the image recorded matter on which the image is disposed to obtain a laminated body.

[0182] According to the image recording method using the ink set of the present disclosure, an image recording material can be produced that includes a non-permeable substrate and an image recorded on the non-permeable substrate, and that has excellent lamination strength after boiling treatment when a laminating substrate is laminated onto the image.

[0183] Therefore, the image recording method using the ink set of the present disclosure is suitable for use in producing a laminated body comprising the above-mentioned image recorded matter and a laminating substrate laminated to the side of the image recorded matter on which the image is recorded.

[0184] According to the method for producing a laminate according to one embodiment of the present disclosure, a laminate having excellent lamination strength between an image-recorded material and a substrate for lamination can be produced even when boiling treatment is performed.

[0185] For the process of obtaining an image recording, the image recording method of the present disclosure described above can be referred to. The process for obtaining a laminated body is a process for obtaining a laminated body by laminating a substrate for lamination on the side of the image-recorded body on which the image is arranged. Lamination can be performed by, for example, a method of superimposing and attaching the substrate for lamination on the side of the image-recorded body on which the image is arranged via another layer (for example, an adhesive layer), or a method of superimposing and attaching the substrate for lamination on the side of the image-recorded body on which the image is arranged through a laminator. In the latter case, a commercially available laminator can be used.

[0186] The lamination temperature when laminating is not particularly limited. For example, when the image recording material and the substrate for lamination are attached via another layer (for example, an adhesive layer), the temperature may be in the range of 20°C or higher. Furthermore, when a laminator is used, the temperature of the laminating rolls may be in the range of 20°C to 80°C. The pressure of the laminating roll pair may be appropriately selected as needed.

[0187] The substrate for lamination is preferably a resin substrate, and is not particularly limited, but examples thereof include substrates made of thermoplastic resins.

[0188] The resin substrate may be, for example, a substrate formed from a thermoplastic resin in the form of a sheet. The resin substrate preferably contains polypropylene, polyethylene terephthalate, nylon, polyethylene, or polyimide.

[0189] The shape of the resin substrate is not particularly limited, but it is preferably a sheet-shaped resin substrate The thickness of the resin substrate is preferably 10 μm to 200 μm, more preferably 10 μm to 100 μm.

[0190] In the step of obtaining a laminate, the substrate for lamination may be laminated directly onto the side of the image-recorded product on which the image is arranged, or may be laminated via another layer (for example, an adhesive layer).

[0191] When the substrate for lamination is directly laminated onto the side of the image-recorded product on which the image is disposed, the lamination can be carried out by a known method such as thermocompression bonding or heat fusion bonding.

[0192] Furthermore, when laminating a substrate for lamination via an adhesive layer onto the side of an image recorded material on which an image is disposed, the lamination can be carried out, for example, by applying an adhesive to the side of the image recorded material on which the image is disposed, then placing the substrate for lamination on the side, and then bonding the image recorded material and the substrate for lamination together.

[0193] Furthermore, lamination via an adhesive layer on the image-bearing side of the image-recorded product can also be carried out by a method such as extrusion lamination (i.e., sandwich lamination).

[0194] The adhesive layer preferably contains an isocyanate compound. When the adhesive layer contains an isocyanate compound, the adhesion between the adhesive layer and the image is further improved, and therefore the lamination strength can be further improved.

[0195] [Image Recording] An image recording material that is one embodiment of the present disclosure comprises a non-permeable substrate and an image disposed on the non-permeable substrate, the image comprising: a pretreatment layer disposed on the non-permeable substrate and containing a resin; and an ink layer disposed on the pretreatment layer and containing a pigment and a resin, wherein the equilibrium moisture content of the pretreatment layer at 25°C and 50% RH is 3.0 mass% or less, and the equilibrium moisture content of the ink layer at 25°C and 50% RH is 3.0 mass% or less.

[0196] A laminate obtained by laminating a lamination substrate onto an image recorded product according to one embodiment of the present disclosure has excellent lamination strength when subjected to boiling treatment.

[0197] The preferred embodiments of each component in the image recording material are the same as the preferred embodiments of each component described in the section on the ink set of this disclosure.

[0198] [Laminated body] A laminated body according to one embodiment of the present disclosure includes the image recorded matter of the present disclosure described above and a lamination substrate laminated onto the image of the image recorded matter.

[0199] The laminate according to one embodiment of the present disclosure has excellent laminate strength when subjected to boiling treatment.

[0200] In the laminate, the substrate for lamination may be laminated directly onto the side of the image-recorded product on which the image is disposed, or may be laminated via another layer (adhesive layer).

[0201] The laminate of the present disclosure is preferably produced by the method for producing the laminate of the present disclosure.

[0202] The preferred embodiments of the substrate for lamination and the adhesive layer are the same as those described in the section on the method for producing the laminate. [Example]

[0203] Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples as long as it does not depart from the gist of the disclosure.

[0204] <Preparation of pretreatment solution> The following components were mixed in the following amounts to prepare a pretreatment liquid. Flocculant: glutaric acid...4.1% by mass Resin emulsion listed in Table 1 or Table 2: 6% by mass (content as resin particles, which are solids) Propylene glycol...10% by mass ·Water…79.9% by mass

[0205] <Ink Preparation> In preparing the ink, first, a pigment dispersion was prepared.

[0206] (Preparation of pigment dispersion 1) -Synthesis of uncrosslinked resin- A monomer feed composition was prepared by combining 200 parts by weight of methacrylic acid, 800 parts by weight of benzyl methacrylate, and 375 parts by weight of isopropanol. An initiator feed composition was prepared by combining 22.05 parts by weight of 2,2-azobis(2-methylbutyronitrile) and 187.5 parts by weight of isopropanol. Next, isopropanol (187.5 parts by mass) was heated to 80°C under a nitrogen atmosphere, and the mixture of the monomer supply composition and the initiator supply composition was added dropwise thereto over 2 hours. After completion of the dropwise addition, the resulting solution was maintained at 80°C for an additional 4 hours and then cooled to 25°C. After cooling, the solvent was removed under reduced pressure to obtain an uncrosslinked resin having a weight average molecular weight of 30,000 and an acid value of 130 mgKOH / g.

[0207] -Crosslinking treatment- 0.8 equivalents of methacrylic acid in the obtained uncrosslinked resin (150 parts by mass) was neutralized using an aqueous potassium hydroxide solution, and then water was added to adjust the concentration of the uncrosslinked resin after neutralization to 25% by mass, thereby obtaining an aqueous solution of the neutralized uncrosslinked resin. The neutralized uncrosslinked resin solution (50 parts by weight), Pigment Blue 15:3 (cyan pigment) (50 parts by weight), water (190 parts by weight), and dipropylene glycol (30 parts by weight) were mixed and dispersed using a beads mill (bead diameter 0.1 mm, zirconia beads) to obtain a dispersion in which the cyan pigment was dispersed by the uncrosslinked resin (uncrosslinked dispersion). The pigment concentration of the cyan pigment was 15% by weight. To this uncrosslinked dispersion (136 parts by mass), a crosslinking agent (product name "Denacol EX-321" manufactured by Nagase ChemteX Corporation) (1.8 parts) and a boric acid aqueous solution (boric acid concentration: 4% by mass) (14.3 parts) were added, and the mixture was allowed to react at 50°C for 6.5 hours. After that, the mixture was cooled to 25°C, and the uncrosslinked resin was crosslinked by the crosslinking agent. This resulted in a dispersion (crosslinked dispersion) in which the cyan pigment was dispersed with crosslinked resin 1. Note that crosslinked resin 1 is a crosslinked form of the uncrosslinked resin. Next, water was added to the resulting crosslinked dispersion, and ultrafiltration was carried out using a stirring type ultraholder (manufactured by ADVANTEC) and an ultrafiltration filter (manufactured by ADVANTEC, molecular weight cutoff 50,000, Q0500076E ultrafilter). After purifying the crosslinked dispersion so that the dipropylene glycol concentration was 0.1% by mass or less, the dispersion was concentrated to a pigment concentration of 15% by mass, thereby obtaining a dispersion in which the cyan pigment was dispersed using crosslinked resin 1 (cyan pigment concentration 15% by mass). In the pigment dispersion 1, at least a portion of the surface of the cyan pigment is covered with the crosslinked resin 1. The acid value of the crosslinked resin 1 was 60 mgKOH / g.

[0208] (Preparation of pigment dispersion 2) Pigment dispersion liquid 2 was obtained in the same manner as in the preparation of pigment dispersion liquid 1, except that the amount of the potassium hydroxide aqueous solution and the amount of the crosslinking agent in the preparation of pigment dispersion liquid 1 were changed so that the acid value of the crosslinked resin would be 36 mgKOH / g. In the pigment dispersion 2, at least a portion of the surface of the cyan pigment is covered with the crosslinked resin 2. The acid value of the crosslinked resin 2 was 36 mg KOH / g.

[0209] (Preparation of pigment dispersion 3) Pigment Dispersion 3 was obtained in the same manner as Pigment Dispersion 1, except that the methacrylic acid (200 parts) and benzyl methacrylate (800 parts) in the monomer supply composition were changed to methacrylic acid (250 parts) and benzyl methacrylate (750 parts), respectively. In the pigment dispersion 3, at least a portion of the surface of the cyan pigment is covered with the crosslinked resin 3. The acid value of the crosslinked resin 3 was 100 mgKOH / g.

[0210] (Ink Preparation) The following components were added to the prepared pigment dispersion liquid to prepare inks. Note that Pigment Dispersion Liquid 2 was used in Example 15, and Pigment Dispersion Liquid 3 was used in Example 16. Pigment Dispersion Liquid 1 was used in the other Examples and Comparative Examples. Pigment dispersion: Amount that results in a pigment concentration of 4% by mass Resin particles listed in Table 1 or Table 2: The amount of resin particles that is the solid content listed in Table 1 or Table 2 Propylene glycol...20% by mass Propylene glycol monomethyl ether...5% by mass Surfactant: Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) ... 1% by mass Water: The remaining amount that makes up 100% of the total ink mass.

[0211] Details of the resins listed in Tables 1 and 2 are as follows: Emulsion refers to a dispersion containing a resin, in which the resin exists as resin particles. Water-soluble resin refers to an aqueous solution containing a resin. In Tables 1 and 2, in the column for resin type, styrene-acrylic resin is simply listed as "acrylic resin." Neocryl A-1105: Acrylic resin emulsion, manufactured by DSM Neocryl XK-110: Styrene acrylic resin emulsion, manufactured by DSM Vinyblan 715: vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Neocryl XK-555: Acrylic resin emulsion, manufactured by DSM Hi-Loss M-141: Acrylic resin emulsion, manufactured by Seiko PMC Neoreds R-4000: Urethane resin emulsion, manufactured by DSM Neocryl A-1091: Styrene acrylic resin emulsion, manufactured by DSM Neocryl A-2091: Styrene acrylic resin emulsion, manufactured by DSM Hi-Loss QE-1042: Styrene acrylic resin emulsion, manufactured by Seiko PMC Neocryl A-1092: Styrene acrylic resin emulsion, manufactured by DSM Vinyblan 2687: Acrylic resin emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Neocryl XK-88: Styrene acrylic resin emulsion, manufactured by DSM Superflex 620: Urethane resin emulsion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Auroren AE-202: Olefin resin emulsion, manufactured by Nippon Paper Industries Co., Ltd. Joncryl 61J: Water-soluble styrene acrylic resin, manufactured by BASF Movinyl 972: Styrene acrylic resin emulsion, manufactured by Japan Coating Resin Co., Ltd. Vinyblan 711: vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Vinyblan A70J9: Vinyl acetate emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Chaline R-170S: Acrylic silicone resin emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Vinyblan 1129: Vinyl acetate emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Superflex 650: Urethane resin emulsion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Superflex 500M: Urethane resin emulsion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Permarin UC-20: Urethane resin emulsion, manufactured by Sanyo Chemical Industries, Ltd. Movinyl 7720: Acrylic resin emulsion, manufactured by Japan Coating Resin Co., Ltd. Acrylit UW-550CS: Acrylic resin emulsion, manufactured by Taisei Fine Chemical Co., Ltd. NS313X: Urethane resin emulsion, manufactured by Takamatsu Oil & Fat Co., Ltd. Pluscoat Z-446: Water-soluble polyester resin, manufactured by GOO Chemical Industry Co., Ltd. Hardlen EW-5313: Olefin resin emulsion, manufactured by Toyobo Co., Ltd. Joncryl 537: Acrylic resin emulsion, manufactured by BASF Vinyblan 700: vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Vinyblan 701: vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd. Joncryl PDX-7700: Styrene acrylic resin emulsion, manufactured by BASF JONCRYL 840: Acrylic resin emulsion, manufactured by BASF

[0212] [Image recording] An image was recorded using the prepared pretreatment liquid and ink. An inkjet recording apparatus was prepared, which was equipped with a conveying system for continuously conveying a long substrate, a wire bar coater for applying a pretreatment liquid to the substrate, and an inkjet head for applying ink to the surface of the substrate to which the pretreatment liquid had been applied. Furthermore, a non-permeable polyethylene terephthalate (PET) substrate ("FE2001" manufactured by Futamura Chemical Co., Ltd., thickness 25 μm, width 500 mm, length 2000 m; hereinafter referred to as "non-permeable substrate A") was prepared as the substrate.

[0213] Using an inkjet recording apparatus, a cyan solid image was recorded on the non-permeable substrate A while the substrate A was continuously conveyed at 635 mm / sec in the following manner. The above pretreatment liquid was applied to the non-permeable substrate A at a rate of approximately 1.7 g / m using a wire bar coater. 2 Then, the mixture was dried at 50°C for 2 seconds. Next, the above ink was applied in the form of a solid image to the surface of the non-permeable substrate A on which the pretreatment liquid had been applied under the following application conditions, and the applied ink was dried at 80°C for 30 seconds to record a solid image. The pretreatment liquid and the ink were both dried by hot air drying.

[0214] -Ink application conditions- Inkjet head: 1200dpi / 20inch wide piezo full line head Ink discharge volume from inkjet head: 4.0 pL Drive frequency: 30kHz (substrate conveying speed: 635mm / sec)

[0215] [evaluation] For each example and each comparative example, the laminate strength of the image recorded product, the laminate strength after boiling treatment, and the character quality were evaluated. The evaluation methods are as follows. The evaluation results are shown in Tables 1 and 2.

[0216] (Laminate strength) According to the above image recording, an image recorded matter in which a solid image was recorded on the non-permeable substrate A was obtained. A 500 mm long x 500 mm wide area (hereinafter also referred to as a laminate strength evaluation area) having a solid image on the entire surface was cut out from the image recording material to provide a laminate strength evaluation sample. A dry laminating adhesive (main agent TM-320 (isocyanate compound) / curing agent CAT-13B (alcohol compound), manufactured by Toyo-Morton Co., Ltd.) was applied to the solid image of the laminate strength evaluation sample using a bar coater, and a linear low-density polyethylene film (product name "LL-XMTN", manufactured by Futamura Chemical Co., Ltd., thickness 40 μm) was placed on top of it as a laminating substrate. In this state, the laminating substrate and the laminate strength evaluation sample were bonded together to obtain a laminate.

[0217] The resulting laminate was aged at 40°C for 48 hours. A sample piece measuring 100 mm in length and 15 mm in width was cut out from the aged laminate. Next, the laminate substrate and the laminate strength evaluation sample were manually peeled off in a region of 30 mm from one longitudinal end of the sample piece, while the laminate substrate and the laminate strength evaluation sample remained stuck together in the remaining region of 70 mm. Next, a tensile test was conducted in which the peeled portion of the sample piece, the substrate for lamination, and the peeled portion of the sample for evaluating laminate strength, were pulled in opposite directions, perpendicular to the remaining 70 mm region (the region where the substrate for lamination and the sample for evaluating laminate strength remained bonded together). This tensile test was used to determine the peel strength when the laminate substrate and the laminate strength evaluation sample were peeled off in the remaining 70 mm region. The obtained peel strength was taken as the laminate strength. The evaluation criteria were as follows. The evaluation results are shown in Tables 1 and 2. The tensile test was carried out using a tensile tester (product name "TENSILON RTM-25", manufactured by Orientec Co., Ltd.).

[0218] 5: The lamination strength between the image-recorded material and the lamination substrate is 2N / 15mm or more. 4: The lamination strength between the image-recorded material and the lamination substrate is 1.5 N / 15 mm or more and less than 2 N / 15 mm. 3: The lamination strength between the image-recorded material and the lamination substrate is 1 N / 15 mm or more and less than 1.5 N / 15 mm. 2: The lamination strength between the image-recorded material and the lamination substrate is 0.5 N / 15 mm or more and less than 1 N / 15 mm. 1: The lamination strength between the image-recorded material and the lamination substrate is less than 0.5 N / 15 mm.

[0219] (Laminate strength after boiling) A laminate was prepared in the same manner as in the laminate preparation method described above in the method for evaluating laminate strength.

[0220] The resulting laminate was aged at 40°C for 48 hours. The aged laminate was boiled at 95°C for 40 minutes using an autoclave (small sterilizer) for retort foods (product name "SR-240", manufactured by Tomy Seiko Co., Ltd.). A sample piece measuring 100 mm in length and 15 mm in width was cut out from the laminate after the boiling treatment. Next, a tensile test was performed using the cut sample pieces in the same manner as in the tensile test described above for evaluating laminate strength, and the peel strength was determined. The obtained peel strength was taken as the laminate strength. The evaluation criteria were as follows. The evaluation results are shown in Tables 1 and 2.

[0221] 5: After boiling, the lamination strength between the image-recorded material and the lamination substrate is 2N / 15mm or more. 4: After boiling, the lamination strength between the image-recorded material and the lamination substrate is 1.5 N / 15 mm or more and less than 2 N / 15 mm. 3: After boiling, the lamination strength between the image-recorded material and the lamination substrate is 1 N / 15 mm or more and less than 1.5 N / 15 mm. 2: After boiling, the lamination strength between the image-recorded material and the lamination substrate is 0.5 N / 15 mm or more and less than 1 N / 15 mm. 1: After boiling, the lamination strength between the image-recorded material and the lamination substrate is less than 0.5 N / 15 mm.

[0222] (Text quality) Using the same method as in the image recording described above, an image recording was obtained in which a character image was recorded on the non-permeable substrate A. As the character image, the character shown in Figure 1 (Unicode: U+9DF9) was output at 4 pt, 6 pt, 8 pt, and 10 pt. Here, pt refers to DTP points that represent the font size, and 1 pt is 1 / 72 inch. Character quality was evaluated by observing each character image on the image recording and determining whether it was reproducible. "Reproducible" means that, when viewed from a distance of 0.5 m, the horizontal line indicated by 11 in Figure 1 and the horizontal line indicated by 12 in Figure 1 are separated in the character image shown in Figure 1. The evaluation criteria are as follows: The evaluation results are shown in Tables 1 and 2.

[0223] 5:4pt characters can be reproduced. 4:6pt characters could be reproduced, but 4pt characters could not be reproduced. 3: 8pt characters could be reproduced, but characters of 6pt or less could not be reproduced. 2: 10pt characters could be reproduced, but characters of 8pt or less could not be reproduced. 1:10pt characters could not be reproduced.

[0224] The equilibrium moisture content of the solid content of the pretreatment liquid and ink in Tables 1 and 2 at 25° C. and 50% RH ("moisture content" in Tables 1 and 2) was measured by the following method.

[0225] The pretreatment liquid and ink were each left in a constant temperature bath at 60°C for 24 hours. Furthermore, they were vacuum-dried at 60°C for 3 hours using a vacuum constant temperature dryer (product name "DRV420DA" manufactured by Advantec Co., Ltd.) to obtain solids of the pretreatment liquid and ink. The solids were then left in a constant temperature bath at 25°C and 50% RH for 24 hours. After 24 hours, the moisture content of the solids was measured by a moisture vaporization method using a trace moisture analyzer (product name "CA-200" manufactured by Mitsubishi Chemical Analytical Co., Ltd.). The moisture vaporization temperature was set to 140°C, and a coulometric titration reagent (product name "Aquamicron AKX" manufactured by Mitsubishi Chemical Corporation) was used as the anolyte, and a coulometric titration reagent (product name "Aquamicron CxU" manufactured by Mitsubishi Chemical Corporation) was used as the catholyte.

[0226] In Tables 1 and 2, for the pretreatment liquid, data on the flocculant contained in the pretreatment liquid, the resin contained in the pretreatment liquid, and the equilibrium moisture content of the solid content at 25°C and 50% RH are listed. For the ink, data on the resin contained in the ink and the equilibrium moisture content of the solid content at 25°C and 50% RH are listed. The resin contained in the ink is divided into the resin used as a dispersant, resin particles A with an acid value of less than 30 mgKOH / g, and resin particles B with an acid value of 30 mgKOH / g or more. In Tables 1 and 2, the unit of acid value is omitted, but it is "mgKOH / g." Furthermore, in Tables 1 and 2, "resin particles A / resin particles B" refers to the content of resin particles A relative to the content of resin particles B. Furthermore, "-" is entered when the component listed in each column is not contained. As mentioned above, JONCRYL 61J and PLASCOAT Z-446 are water-soluble resins, but they are listed in the resin particle column.

[0227] [Table 1]

[0228] [Table 2]

[0229] As shown in Table 1, in Examples 1 to 19, the pretreatment liquid contained a resin and water, the ink contained a pigment, a resin, and water, and the equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH was 3.0% by mass or less, and the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH was 3.0% by mass or less. Therefore, it was found that the laminate strength after boiling treatment was excellent.

[0230] On the other hand, as shown in Table 2, in Comparative Examples 1 to 20, one or both of the equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH and the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH exceeded 3.0 mass%, and therefore it was found that the laminate strength after boiling treatment was poor.

[0231] In Example 2, the equilibrium moisture content of the ink solids at 25°C and 50% RH was 1.5% by mass or less, and therefore, compared with Examples 3 to 6, it was found to be superior in laminate strength after boiling treatment.

[0232] In Example 10, the ink contains resin particles with an acid value of less than 30 mgKOH / g and resin particles with an acid value of 30 mgKOH / g or more, and therefore, it was found that the character quality was superior to that of Example 2.

[0233] In Examples 11 to 13, 15, and 16, the mass ratio of the content of resin particles with an acid value of less than 30 mgKOH / g to the content of resin particles with an acid value of 30 mgKOH / g or more was 1.5 to 4.0, and therefore it was found that the laminate strength, the laminate strength after boiling treatment, and the character quality were all superior compared to Examples 10 and 14.

[0234] In Example 17, the resin contained in the pretreatment liquid and the resin contained in the ink were both acrylic resins, and therefore, compared to Examples 18 and 19, it was found that the laminate strength and the laminate strength after boiling treatment were superior.

[0235] The disclosure of Japanese Patent Application No. 2021-015957, filed on February 3, 2021, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. a pretreatment liquid containing a resin and water; an ink containing a pigment, a resin, and water; the pretreatment liquid has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% RH; and the ink has a solid content of 3.0% by mass or less at 25°C and 50% RH; the resin contained in the ink includes a resin having an acid value of 30 mgKOH / g or less; Inkjet ink set for non-porous substrates.

2. 2. The inkjet ink set for non-permeable substrates according to claim 1, wherein the equilibrium moisture content of the solid content of the pretreatment liquid at 25°C and 50% RH is lower than the equilibrium moisture content of the solid content of the ink at 25°C and 50% RH.

3. The inkjet ink set for non-permeable substrates according to claim 1 or 2, wherein the resin contained in the inks comprises resin particles.

4. 4. The inkjet ink set for non-permeable substrates according to claim 1, wherein the resin contained in the inks comprises resin particles having an acid value of less than 30 mgKOH / g and resin particles having an acid value of 30 mgKOH / g or more.

5. 5. The inkjet ink set for non-permeable substrates according to claim 4, wherein a mass ratio of a content of the resin particles having an acid value of less than 30 mgKOH / g to a content of the resin particles having an acid value of 30 mgKOH / g or more is 1.5 to 4.

0.

6. The inkjet ink set for non-permeable substrates according to any one of claims 1 to 5, wherein the equilibrium water content of the solid content of the ink at 25°C and 50% RH is 1.5% by mass or less.

7. 7. The inkjet ink set for non-permeable substrates according to claim 1, wherein the pretreatment liquid has an equilibrium water content of 1.5% by mass or less at 25° C. and 50% RH in terms of solid content.

8. 8. The inkjet ink set for non-permeable substrates according to claim 1, wherein the resin contained in the pretreatment liquid and the resin contained in the ink are each an acrylic resin or a urethane resin.

9. The inkjet ink set for non-permeable substrates according to any one of claims 1 to 8 is used, applying the pretreatment liquid onto an impermeable substrate; and applying the ink by an ink jet recording method onto the non-permeable substrate to which the pretreatment liquid has been applied, thereby recording an image.

10. A step of obtaining an image recorded matter comprising the impermeable substrate and an image disposed on the impermeable substrate by the image recording method according to claim 9; a step of laminating a substrate for lamination onto the side of the image-recorded product on which the image is arranged to obtain a laminate; A method for producing a laminate comprising the steps of:

11. an impermeable substrate; and an image disposed on the impermeable substrate; The image is a pretreatment layer disposed on the impermeable substrate and containing a resin; an ink layer disposed on the pretreatment layer and containing a pigment and a resin; The pretreatment layer has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% RH, and the ink layer has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% RH; the resin contained in the ink layer includes a resin having an acid value of 30 mgKOH / g or less; Image recording.

12. The image recording material according to claim 11; a lamination substrate laminated onto the image of the image recording material; A laminate body comprising:

Images