Inkjet ink set for non-permeable substrate, image recording method, image recorded article, laminate, and method for producing laminate

Abstract

The present invention provides an inkjet ink set for non-permeable substrates and its use. The inkjet ink set for non-permeable substrates comprises: a pretreatment liquid containing a resin and water; and an ink containing a pigment, a resin, and water. The equilibrium moisture content of the solid components 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 components of the ink at 25°C and 50% RH is 3.0% by mass or less.

Description

Technical Field

[0001] The present invention relates to an inkjet ink set for non-permeable substrates, an image recording method, an image-recorded article, a laminate, and a method for producing the laminate. Background Art

[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 comprising at least: an ink composition containing a resin having a water absorption of 0.3% or less and water; and a reaction solution containing a coagulant having a solubility of 120 g or less in 100 g of water, which acts as a coagulant for aggregating the components of the ink composition. This ink set is used for recording on low-absorbent or non-absorbent recording media. Summary of the Invention

[0004] Technical issues to be solved by the invention

[0005] After an image is recorded on an impermeable substrate to produce an image-recorded material, a laminating substrate is sometimes laminated onto the image-recorded material to produce a laminate. Furthermore, if the laminate is subjected to a boiling treatment, it is sometimes necessary to increase the lamination strength between the image-recorded material and the laminating substrate.

[0006] The present invention has been made in view of such circumstances. According to one embodiment of the present invention, there is provided an inkjet ink set for a non-permeable substrate and an image recording method, which are capable of obtaining an image recorded material having excellent lamination strength. The lamination strength is the lamination strength obtained when a laminating substrate is laminated on an image recorded material to produce a laminate and the laminate is subjected to a boiling treatment.

[0007] According to another embodiment of the present invention, there is provided a method for producing a laminated body capable of producing a laminated body having excellent lamination strength between a lamination substrate and an image recorded material after being subjected to a boiling treatment.

[0008] According to another embodiment of the present invention, there is provided an image recorded material having excellent lamination strength when a laminate is subjected to a boiling treatment.

[0009] Another embodiment of the present invention aims to provide a laminate having excellent lamination strength between a laminating substrate and an image recorded material when subjected to a boiling treatment.

[0010] Means for solving technical problems

[0011] The present invention includes the following aspects.

[0012] <1> An inkjet ink set for non-permeable substrates comprises: a pretreatment liquid containing a resin and water; and 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% relative humidity (RH), and the ink has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% relative humidity (RH).

[0013] <2> according to <1> In the inkjet ink set for non-permeable substrates, the equilibrium moisture content of the solid components of the pre-treatment liquid at 25° C. and 50% RH is lower than the equilibrium moisture content of the solid components of the ink at 25° C. and 50% RH.

[0014] <3> according to <1> or <2> In the inkjet ink set for non-permeable substrates, the resin contained in the ink comprises resin particles.

[0015] <4> according to <1> to <3> The inkjet ink set for non-permeable substrates according to any one of the preceding claims, wherein the resin contained in the ink 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.

[0016] <5> according to <4> In the inkjet ink set for non-permeable substrates, 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.

[0017] <6> according to <1> to <5> The inkjet ink set for non-permeable substrates according to any one of the preceding claims, wherein the equilibrium moisture content of the solid content of the ink at 25° C. and 50% RH is 1.5% by mass or less.

[0018] <7> according to <1> to <6> The inkjet ink set for non-permeable substrates according to any one of the preceding claims, wherein the pre-treatment liquid has an equilibrium moisture content of 1.5% by mass or less of the solid content at 25° C. and 50% RH.

[0019] <8> according to <1> to <7> In any one of the inkjet ink sets for non-permeable substrates, the resin contained in the pre-treatment liquid and the resin contained in the ink are each an acrylic resin or a urethane resin.

[0020] <9> An image recording method using <1> to <8> The image recording method of the inkjet ink set for non-permeable substrates comprises: applying a pre-treatment liquid to the non-permeable substrate; and applying ink to the non-permeable substrate applied with the pre-treatment liquid using an inkjet recording method to record an image.

[0021] <10> A method for manufacturing a laminate, comprising: <9> The image recording method comprises the steps of obtaining an image recorded article having an impermeable substrate and an image arranged on the impermeable substrate; and laminating a laminating substrate on the side of the image recorded article where the image is arranged to obtain a laminate.

[0022] <11> An image recorded material comprises an impermeable substrate and an image disposed on the impermeable substrate, the image comprising: 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 pretreatment layer has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% relative humidity, and the ink layer has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% relative humidity.

[0023] <12> A laminate comprising: <11> The image recorded article; and a laminating substrate laminated on the image of the image recorded article.

[0024] Effects of the Invention

[0025] According to one embodiment of the present invention, an inkjet ink set for an impermeable substrate and an image recording method are provided, which can produce an image recorded article having excellent lamination strength, the lamination strength being the lamination strength when a laminating substrate is laminated on an image recorded article to produce a laminate and the laminate is subjected to a boiling treatment.

[0026] According to another embodiment of the present invention, there is provided a method for producing a laminated body capable of producing a laminated body having excellent lamination strength between a lamination substrate and an image recorded material after being subjected to a boiling treatment.

[0027] According to another embodiment of the present invention, there is provided an image recorded material having excellent lamination strength when a laminate is subjected to a boiling treatment.

[0028] According to another embodiment of the present invention, there is provided a laminate having excellent lamination strength between a laminating substrate and an image recorded material when subjected to a boiling treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram for explaining the details of the character quality evaluation criteria in the embodiment. DETAILED DESCRIPTION

[0030] Hereinafter, the inkjet ink set for non-permeable substrates, the image recording method, and the method for producing a laminate of the present invention will be described in detail.

[0031] In this specification, a numerical range expressed using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

[0032] Within the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced by the upper limit or lower limit of another numerical range described in another stage. Furthermore, within the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced by the values shown in the Examples.

[0033] In this specification, when a plurality of substances corresponding to each component are present in a composition, the amount of each component in the composition represents the total amount of the plurality of substances present in the composition unless otherwise specified.

[0034] In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0035] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0036] In this specification, “image” refers to the entire film formed by sequentially applying the pre-treatment liquid and the ink, and “image recording” refers to the formation of an image (ie, a film).

[0037] Furthermore, the concept of "image" in this specification also includes a solid image.

[0038] In this specification, "(meth)acrylate" is a concept including both acrylate and methacrylate. Furthermore, "(meth)acrylic acid" is a concept including both acrylic acid and methacrylic acid.

[0039] In this specification, "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 predetermined time (for example, 10 to 120 minutes).

[0040] [Inkjet ink set for non-permeable substrates]

[0041] The inkjet ink set for non-permeable substrates of the present invention (hereinafter also referred to as the "ink set of the present invention") is an 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 solids 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 solids content of the ink at 25°C and 50% RH is 3.0% by mass or less.

[0042] The ink set of the present invention can produce an image recorded article comprising an impermeable substrate and an image recorded on the impermeable substrate, wherein the image recorded article exhibits excellent lamination strength even when a laminate is produced by laminating a laminating substrate on the image and the laminate is subjected to a boiling treatment.

[0043] Here, the lamination strength refers to the peeling strength when peeling the laminating substrate and the image recorded material in the laminate formed by the above lamination [i.e., a laminate having a laminate structure of "laminating substrate / image recorded material" (more specifically, a laminate structure of "laminating substrate / image / impermeable substrate")].

[0044] The reason why the ink set of the present invention exhibits the above-mentioned effects is presumed to be as follows.

[0045] In order to improve the lamination strength of the laminate, it is necessary to improve the adhesion between the non-permeable substrate and the image, and further to improve the adhesion between the image and the lamination substrate.

[0046] In the ink set of the present invention, the equilibrium moisture content of the solids of the pretreatment liquid at 25°C (temperature) and 50% RH (relative humidity) is 3.0% by mass or less, and the equilibrium moisture content of the solids of the ink at 25°C (temperature) and 50% RH (relative humidity) is 3.0% by mass or less. This improves the adhesion between the pretreatment layer formed by applying the pretreatment liquid and the ink layer formed by applying the ink, suppressing internal expansion of the ink layer and improving adhesion between the ink layer and the laminating substrate. This is presumably responsible for increased lamination strength after the boiling treatment.

[0047] On the other hand, the ink set disclosed in Patent Document 1, because the pretreatment liquid contains no resin, is believed to have poor adhesion between the pretreatment layer and the ink layer, resulting in insufficient lamination strength after boiling. Furthermore, in ink sets containing a pretreatment liquid and ink, the equilibrium moisture content of the pretreatment liquid and ink at 25°C and 50% RH has not been considered.

[0048] Hereinafter, each component contained in the pre-treatment liquid and the ink of the ink set of the present invention will be described.

[0049] [Ink Set]

[0050] <Ink>

[0051] The ink in the ink set of the present invention contains a pigment, a resin, and water.

[0052] (pigment)

[0053] The ink contained in the ink set of the present invention contains a pigment. The pigment contained in the ink may be one type or two or more types.

[0054] The pigment may be any of conventional commercially available organic pigments and inorganic pigments. Examples of the pigment include the pigments described in "Encyclopedia of Pigments" (published in 2000) edited by Seishiro Ito, W. Herbst, K. Hunger "Industrial Organic Pigments," Japanese Patent Publication No. 2002-12607, Japanese Patent Publication No. 2002-188025, Japanese Patent Publication No. 2003-26978, and Japanese Patent Publication No. 2003-342503.

[0055] Furthermore, the pigment may be a water-insoluble pigment that can be dispersed in water using a dispersant, or a self-dispersible pigment. A self-dispersible pigment is a pigment that can be dispersed in water even without a dispersant. For example, a self-dispersible pigment is a compound in which at least one hydrophilic group selected from the group consisting of carbonyl, hydroxyl, carboxyl, sulfonyl, phosphate, and their salts is chemically bonded to the surface of the pigment directly or via other groups.

[0056] 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 chelated azo pigments. Examples of polycyclic pigments include phthalocyanine pigments, perylene pigments, perylene ketone 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.

[0057] Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black.

[0058] From the viewpoint of image density and ink jetting properties, the content of the pigment in the ink is preferably 1 to 20% by mass, more preferably 1 to 15% by mass, and even more preferably 1 to 10% by mass, relative to the total amount of the ink.

[0059] (resin)

[0060] The ink contained in the ink set of the present invention contains a resin. The resin contained in the ink may be one type or two or more types.

[0061] The resin contained in the ink may be a dispersant that functions to disperse the pigment contained in the ink, or it may be a resin added to the ink separately from the dispersant. Therefore, the ink may contain only a resin that functions as a dispersant, or it may contain both a resin that functions as a dispersant and a resin other than the dispersant. Furthermore, if the pigment contained in the ink is a self-dispersing pigment, the ink may contain only a resin other than the dispersant.

[0062] The type of resin contained in the ink is not particularly limited. Examples include acrylic resins, epoxy resins, urethane resins, polyethers, polyamides, phenolic resins, silicone resins, fluororesins, vinyl resins (e.g., vinyl chloride resins, vinyl acetate resins, vinyl alcohol resins, and vinyl butyral resins), alkyd resins, polyester resins, melamine resins, melamine-formaldehyde resins, aminoalkyd co-condensation resins, and urea resins. Of these, acrylic resins or urethane resins are preferred from the perspective of improving lamination strength and lamination strength after boiling treatment.

[0063] In the present invention, an acrylic resin refers to a polymer containing a structural unit 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 the (meth)acrylic compound include (meth)acrylic acid, (meth)acrylates, and (meth)acrylamide. In acrylic resins, examples of structural units other than structural units derived from (meth)acrylic compounds include structural units derived from styrene. Styrene acrylic resins are included in acrylic resins.

[0064] In the present invention, the term "carbamate resin" refers to a polymer containing a carbamate bond. The carbamate resin is synthesized, for example, by the reaction of a diol compound and a diisocyanate compound. For details of the diol compound and the diisocyanate compound, reference can be made to paragraphs 0031 to 0036 of Japanese Patent Application Laid-Open No. 2001-247787. The carbamate resin is preferably a polyester carbamate resin having an ester bond in the main chain, a polycarbonate carbamate resin having a carbonate bond in the main chain, or a polyether carbamate resin having an ether bond in the main chain, and more preferably a polycarbonate carbamate resin.

[0065] From the perspective of jetting performance, the resin content 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, relative to the total amount of the ink. The lower limit of the resin content is not particularly limited, but is, for example, 0.1% by mass.

[0066] -Resin that functions as a dispersant-

[0067] The resin that functions as a dispersant is usually premixed with the pigment and included in the pigment dispersion. The resin that functions as a dispersant can be appropriately selected from conventionally known dispersants and may be a random copolymer or a block copolymer. Furthermore, the resin that functions as a dispersant may have a cross-linked structure.

[0068] The resin that functions as a dispersant is preferably a resin having a cross-linked structure (hereinafter also referred to as a "cross-linked resin"). Specifically, the ink contained in the ink set of the present invention preferably contains a cross-linked resin. The cross-linked resin, which functions as a dispersant, coats a portion of the pigment surface, thereby dispersing the pigment in water. The cross-linked resin is less likely to detach from the pigment surface, thus enabling stable pigment dispersion.

[0069] The cross-linked resin is formed by cross-linking an uncross-linked resin (hereinafter, also referred to as “uncross-linked resin”).

[0070] The uncrosslinked resin is preferably water-soluble.

[0071] In the present invention, "water-soluble" means that 1 g or more dissolves in 100 g of water at 25° C. "Water-soluble" preferably means that 3 g or more (more preferably 10 g or more) dissolves in 100 g of water at 25° C.

[0072] Furthermore, even if the uncrosslinked resin is water-soluble, the crosslinked resin is not necessarily water-soluble.

[0073] Examples of the uncrosslinked resin include vinyl resins, acrylic resins, urethane resins, and polyester resins. Among them, the uncrosslinked resin is preferably an acrylic resin.

[0074] The uncrosslinked resin is preferably a polymer having functional groups that can be crosslinked by a crosslinking agent. Examples of crosslinkable functional groups include carboxyl groups or salts thereof, isocyanate groups, and epoxy groups. From the perspective of improving the dispersibility of the pigment, the crosslinkable functional group is preferably a carboxyl group or a salt thereof, and particularly preferably a carboxyl group. In other words, the uncrosslinked resin is preferably a polymer containing a carboxyl group.

[0075] The uncrosslinked resin is preferably a copolymer containing a structural unit derived from a monomer containing a carboxyl group (hereinafter referred to as a "carboxyl group-containing monomer"). The structural unit derived from the carboxyl group-containing monomer contained in the copolymer may be of only one type or of two or more types. The copolymer may be a random copolymer or a block copolymer, but is preferably a random copolymer.

[0076] Examples of the carboxyl group-containing monomer include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid.

[0077] From the viewpoint of crosslinking properties and dispersibility, the carboxyl group-containing monomer is preferably (meth)acrylic acid or β-carboxyethyl acrylate, and more preferably (meth)acrylic acid.

[0078] The content of the structural unit derived from the carboxyl group-containing monomer is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the uncrosslinked resin.

[0079] The uncrosslinked resin preferably contains a structural unit derived from a hydrophobic monomer in addition to the structural unit derived from the carboxyl group-containing monomer. The structural unit derived from the hydrophobic monomer contained in the copolymer may be of only one type or of two or more types.

[0080] Examples of the hydrophobic monomer include (meth)acrylates having an alkyl group having 1 to 20 carbon atoms, (meth)acrylates having an aromatic ring (for example, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), styrene, and styrene derivatives.

[0081] The content of the structural unit derived from the hydrophobic monomer is preferably 60 to 95% by mass, more preferably 65 to 90% by mass, and even more preferably 70 to 90% by mass, based on the total amount of the uncrosslinked resin.

[0082] The uncrosslinked resin is preferably a random copolymer containing at least one of a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 20 carbon atoms and a structural unit derived from a (meth)acrylate having an aromatic ring, and a structural unit derived from a carboxyl group-containing monomer. It is 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. It is even more preferably a copolymer containing a structural unit derived from (meth)acrylic acid and a structural unit derived from benzyl (meth)acrylate.

[0083] The weight average molecular weight (MW) of the uncrosslinked resin is not particularly limited, but is preferably 3,000 to 300,000, more preferably 5,000 to 200,000, and even more preferably 7,000 to 100,000 from the viewpoint of dispersibility of the white pigment.

[0084] The preferred range of the weight average molecular weight of the cross-linked resin is also the same as the preferred range of the weight average molecular weight of the uncross-linked resin.

[0085] In the present invention, the weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC). HLC-8220GPC (manufactured by Tosoh Corporation) is used in GPC. As a column, three TSKgeL SuperHZM-H, TSKgeLSuperHZ4000, and TSKgel SuperHZ2000 (all trade names manufactured by Tosoh Corporation) are connected in series, and THF (tetrahydrofuran) is used as an eluent. In addition, as a condition, the sample concentration is set to 0.45% by mass, the flow rate is set to 0.35 ml / min, the sample injection amount is set to 10 μl, the measurement temperature is set to 40 ° C, and a differential refractive index detector is used. The calibration curve is prepared based on eight samples of "standard sample TSK standard, polystyrene (polystyrene)" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0086] The crosslinking agent used to crosslink the uncrosslinked resin is preferably a compound having two or more reactive sites that react with the uncrosslinked resin (eg, a polymer having a carboxyl group).

[0087] 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-functional epoxy compound) and a polymer having a carboxyl group. In this combination, a crosslinked structure is formed by the reaction of the epoxy and carboxyl groups. It is preferred that the crosslinked structure be formed by the crosslinking agent after the pigment is dispersed in the uncrosslinked resin.

[0088] Examples of the bifunctional or higher-functional epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.

[0089] Among them, the bifunctional or higher-functional epoxy compound is preferably polyethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, or trimethylolpropane triglycidyl ether.

[0090] The cross-linking agent may be a commercially available product.

[0091] Examples of commercially available products include Denacol EX-321, EX-821, EX-830, EX-850, and EX-851 (manufactured by Nagase ChemteX Corporation).

[0092] From the viewpoint of the crosslinking reaction rate and the dispersion stability after crosslinking, the molar ratio of the reactive sites in the crosslinking agent (e.g., epoxy groups) to the reactive sites in the uncrosslinked resin (e.g., carboxyl groups) 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.

[0093] - Resins other than resins that function as dispersants -

[0094] The ink can be prepared by, for example, adding a resin other than the resin that functions as a dispersant to the pigment dispersion. Examples of the resin to be added later include water-soluble resins and resin particles.

[0095] The water-soluble resin can be selected from the water-soluble uncrosslinked resins mentioned above. Examples of the water-soluble resin include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble cellulose derivatives, polyethylene glycol, and poly(meth)acrylonitrile. Their water solubility is as described above.

[0096] The resin contained in the ink set of the present invention preferably comprises resin particles. When the ink contains resin particles, when applied to an impermeable substrate treated with a pretreatment liquid, the resin particles in the ink come into contact with the pretreatment liquid, causing the aggregation or dispersion of the resin particles to become unstable and causing the ink to thicken. This suppresses interference between falling ink droplets, improving image quality. Furthermore, the presence of resin particles in the ink enhances the strength of the ink film, thereby increasing the lamination strength of the image recorded. The resin contained in the ink preferably comprises particles of acrylic resin or urethane resin.

[0097] The resin contained in the resin particles may be only one type or two or more types.

[0098] The resin contained in the resin particles is preferably a water-insoluble resin.

[0099] In the present invention, the "water-insoluble" in the water-insoluble resin means a property in which the amount of the water-insoluble resin dissolved in 100 g of water at 25°C is less than 1.0 g (more preferably less than 0.5 g).

[0100] The resin particles preferably include at least one of particles composed of an acrylic resin (hereinafter referred to as “acrylic resin particles”) and particles composed of a urethane resin (hereinafter also referred to as “urethane resin particles”), and more preferably include acrylic resin particles.

[0101] The resin particles are preferably self-dispersible resin particles.

[0102] Examples of the self-dispersing resin particles include those described in paragraphs 0062 to 0076 of JP-A-2016-188345 and paragraphs 0109 to 0140 of WO 2013 / 180074.

[0103] The resin contained in the resin particles preferably has an aliphatic ring or an aromatic ring, and more preferably has an aromatic ring.

[0104] The aliphatic ring is preferably an alicyclic hydrocarbon having 5 to 10 carbon atoms, and more preferably a cyclohexane ring structure, a dicyclopentane ring structure, a dicyclopentene ring, or an adamantane ring.

[0105] The aromatic ring is preferably a naphthalene ring or a benzene ring, and more preferably a benzene ring.

[0106] From the viewpoint of further improving the water dispersibility of the resin particles, the resin contained in the resin particles preferably has an ionic group.

[0107] The ionic group may be an anionic group or a cationic group, but is preferably an anionic group from the viewpoint of easy introduction.

[0108] The anionic group is not particularly limited, but is preferably a carboxyl group or a sulfo group, and more preferably a sulfo group.

[0109] 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.

[0110] From the perspective of spraying stability, the average particle size 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 size of the resin particles can be determined by measuring the volume average particle size using a dynamic light scattering method using a particle size distribution analyzer (e.g., "NANOTRAC UPA-EX150" manufactured by Nikkiso Co., Ltd.).

[0111] 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 or less. 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 greater, more preferably 2 mgKOH / g or greater.

[0112] From the perspective of improving image quality and lamination strength after boiling treatment, the ink in the ink set of the present invention preferably contains two or more resin particles having different acid values. Specifically, the resin contained in the ink preferably includes resin particles having an acid value of less than 30 mgKOH / g (hereinafter referred to as "resin particles A") and resin particles having an acid value of 30 mgKOH / g or greater (hereinafter referred to as "resin particles B"). Resin particles A and resin particles B may each be of one type or of two or more types.

[0113] To improve lamination strength after boiling treatment, the acid value of resin particles A is preferably 20 mgKOH / g or less, 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, to improve image quality, the acid value of resin particles B is preferably 45 mgKOH / g or more, more preferably 60 mgKOH / g or more. The upper limit of the acid value of resin particles B is, for example, 100 mgKOH / g.

[0114] Furthermore, when two types of resin particles having different acid values are contained, it is preferable that the two types of resin particles have an acid value difference of 30 or more, and it is more preferable that the two types of resin particles have an acid value difference of 50 or more.

[0115] From the viewpoint of lamination 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, further preferably 1.5 to 4.0, and particularly preferably 2.0 to 4.0 from the viewpoint of lamination strength and image quality.

[0116] When ink contains resin particles with an acid value of 30 mgKOH / g or higher, the ink thickens further when applied to an impermeable substrate treated with a pre-treatment solution. This reduces interference between falling ink droplets, further improving image quality. In particular, when the mass ratio is between 1.5 and 4.0, the lamination strength of the image recorded after boiling is enhanced, resulting in excellent image quality.

[0117] In the present invention, the acid value is a value measured by the method described in JIS K0070:1992.

[0118] When the ink contains resin particles as the resin, the content of the resin particles is preferably 1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass, relative to the total amount of the ink.

[0119] (water)

[0120] The ink in the ink set of the present invention contains water. The water content is not particularly limited, but is, for example, 40% to 70% by mass.

[0121] (Organic Solvent)

[0122] The ink in the ink set of the present invention preferably contains an organic solvent. The organic solvent contained in the ink may be one kind or two or more kinds.

[0123] From the viewpoint of spraying stability and lamination strength, the organic solvent preferably contains an organic solvent having a boiling point lower than 200°C, and more preferably contains an organic solvent having a boiling point of 120°C to 200°C.

[0124] The content of an organic solvent having 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 ink. In other words, the ink preferably does not contain an organic solvent having a boiling point of 200°C or higher. If the ink contains an organic solvent, the organic solvent preferably has a boiling point below 200°C.

[0125] 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 after boiling treatment are improved.

[0126] In the present invention, the "boiling point" means the boiling point at 1 atmosphere (101325 Pa). The boiling point is measured with an ebulliometer, for example, using an ebulliometer (product name "DosaTherm 300", manufactured by TITAN TECHNO LOGIES, KK).

[0127] Examples of organic solvents having a boiling point lower than 200° C. include

[0128] Alkylene glycols such as ethylene glycol (197°C) and propylene glycol (187°C);

[0129] 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);

[0130] Esters such as ethylene glycol monomethyl ether acetate (145°C), ethyl acetate (154°C), ethyl lactate (154°C), and 3-methoxybutyl acetate (172°C); and

[0131] Ketones such as diacetone alcohol (169°C), cyclohexanone (156°C), and cyclopentanone (131°C). The numerical values in parentheses indicate boiling points.

[0132] 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.);

[0133] Alkylene glycols such as diethylene glycol (244°C), triethylene glycol (287°C), and dipropylene glycol (230°C);

[0134] 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 (above 261°C), and tripropylene glycol monomethyl ether (243°C); and

[0135] Esters such as diethylene glycol monoethyl ether acetate (217° C.) The numerical values in parentheses indicate boiling points.

[0136] 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.

[0137] (additive)

[0138] The ink may contain additives such as a surfactant, a co-sensitizer, an ultraviolet absorber, an antioxidant, an anti-fading agent, a conductive salt, and an alkaline compound as needed.

[0139] (physical properties)

[0140] 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, but is, for example, 0.1% by mass. The equilibrium moisture content is measured by the following method.

[0141] The ink was placed in a thermostatic bath at 60°C for 24 hours. Furthermore, the ink was vacuum-dried at 60°C for 3 hours using a vacuum thermostatic dryer (product name "DRV420DA", manufactured by ADVANTEC CO., LTD.) to obtain the solid matter (solid content) of the ink. The solid matter of the ink was then placed in a thermostatic bath at 25°C and 50% RH for 24 hours. After 24 hours, the water content of the solid matter of the ink was measured by the moisture vaporization method using a trace moisture analyzer (product name "CA-200", manufactured by Mitsubishi Chemical Analytech 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 for the anolyte, and a coulometric titration reagent (product name "AQUAMICRON CxU", manufactured by Mitsubishi Chemical Corporation) was used for the catholyte.

[0142] Furthermore, depending on the boiling point of the organic solvent contained in the ink, the solid matter of the ink may contain the organic solvent.

[0143] From the viewpoint of improving ejection stability, the pH of the ink is preferably 7 to 10, 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 DKK-TOA CORPORATION (Model “HM-31”).

[0144] The viscosity of the ink is preferably 0.5 to 30 mPa·s, more preferably 2 to 20 mPa·s, even more preferably 2 to 15 mPa·s, and even more preferably 3 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.

[0145] 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 manufactured by Kyowa Interface Science Co., Ltd. (product name "CBVP-Z"), using a plate method.

[0146] <Pretreatment Liquid>

[0147] The pre-treatment liquid in the ink set of the present invention contains a resin and water.

[0148] (resin)

[0149] The pre-treatment liquid contained in the ink set of the present invention contains a resin. The resin contained in the pre-treatment liquid may be one type or two or more types.

[0150] 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 resin contained in the ink. Among them, from the perspective of improving lamination strength, the resin contained in the pretreatment liquid is preferably an acrylic resin or a urethane resin.

[0151] In particular, from the viewpoint of further improving the lamination strength, both the resin contained in the pretreatment liquid and the resin contained in the ink are preferably acrylic resins or urethane resins.

[0152] The resin contained in the pretreatment liquid may be the same as or different from the resin contained in the ink.

[0153] The content of the resin in the pretreatment liquid is preferably 20% by mass or less, more preferably 10% by mass or less, relative to 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.

[0154] Examples of the resin include water-soluble resins and resin particles.

[0155] Examples of the water-soluble resin include the same water-soluble resins as those described in the above ink section.

[0156] From the viewpoint of improving image quality (particularly, character quality), the resin contained in the pre-treatment liquid in the ink set of the present invention preferably contains resin particles.

[0157] The resin contained in the resin particles may be only one type or two or more types.

[0158] The resin contained in the resin particles is preferably a water-insoluble resin.

[0159] The resin particles preferably include at least one of acrylic resin particles and urethane resin particles, and more preferably include acrylic resin particles.

[0160] The resin particles are preferably self-dispersible resin particles.

[0161] Examples of the self-dispersing resin particles include those described in paragraphs 0062 to 0076 of JP-A-2016-188345 and paragraphs 0109 to 0140 of WO 2013 / 180074.

[0162] The resin contained in the resin particles preferably has an aliphatic ring or an aromatic ring, and more preferably has an aromatic ring.

[0163] The aliphatic ring is preferably an alicyclic hydrocarbon having 5 to 10 carbon atoms, and more preferably a cyclohexane ring structure, a dicyclopentane ring structure, a dicyclopentene ring, or an adamantane ring.

[0164] The aromatic ring is preferably a naphthalene ring or a benzene ring, and more preferably a benzene ring.

[0165] From the viewpoint of further improving the water dispersibility of the resin particles, the resin contained in the resin particles preferably has an ionic group.

[0166] The ionic group may be an anionic group or a cationic group, but is preferably an anionic group from the viewpoint of easy introduction.

[0167] The anionic group is not particularly limited, but is preferably a carboxyl group or a sulfo group, and more preferably a sulfo group.

[0168] 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.

[0169] When inkjet recording is performed, the average particle size 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 from the viewpoint of ejection stability. The average particle size of the resin particles can be determined by measuring the volume average particle size using a dynamic light scattering method using a particle size distribution analyzer (e.g., "NANOTRAC UPA-EX150" manufactured by Nikkiso Co., Ltd.).

[0170] 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 lamination strength after boiling treatment is improved.

[0171] (coagulant)

[0172] From the perspective of improving image quality (especially character quality), the pretreatment liquid preferably contains a coagulant. The coagulant is not particularly limited as long as it causes the components in the ink to coagulate. The coagulant is preferably at least one selected from the group consisting of a polyvalent metal compound, an organic acid, a metal complex, and a cationic polymer, and more preferably contains an organic acid.

[0173] -Polyvalent Metal Compounds-

[0174] Examples of polyvalent metal compounds include salts of alkaline earth metals of Group 2 of the periodic table (e.g., magnesium and calcium), transition metals of Group 3 of the periodic table (e.g., lanthanum), metals of Group 13 of the periodic table (e.g., aluminum), and lanthanides (e.g., neodymium).

[0175] The salts of these metals are preferably salts of organic acids described below, nitrates, chlorides, or thiocyanates.

[0176] Among them, the polyvalent metal compound is preferably a calcium salt or magnesium salt of an organic acid (eg, 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 thiocyanate.

[0177] It is preferred that at least a portion of the polyvalent metal compound is dissociated into polyvalent metal ions and counter ions in the pretreatment liquid.

[0178] -Organic acid-

[0179] Examples of the organic acid include organic compounds having an acidic group.

[0180] Examples of the acidic group include a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfonic acid group, and a carboxyl group.

[0181] Among them, from the viewpoint of the aggregation speed of the ink, the acidic group is preferably a phosphoric acid group or a carboxyl group, and more preferably a carboxyl group.

[0182] It is preferred that at least a part of the acidic groups be dissociated in the pretreatment liquid.

[0183] Examples of the organic compound having a carboxyl 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.

[0184] Among them, from the viewpoint of the aggregation speed of the ink, the organic compound having a carboxyl group is preferably a divalent or higher-valent carboxylic acid (hereinafter also referred to as a polyvalent carboxylic acid), and more preferably a dicarboxylic acid.

[0185] 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.

[0186] The organic acid preferably has a low pKa (e.g., 1.0 to 5.0). Thus, contact with an organic acid with a lower pKa can reduce the surface charge of particles such as pigments and resin particles in the ink stabilized by weakly acidic functional groups such as carboxyl groups, thereby reducing dispersion stability.

[0187] The organic acid preferably has a low pKa, high solubility in water, and a valence of 2 or more. Furthermore, the organic acid more preferably has a high buffering capacity in a pH region lower than the pKa of the functional group (eg, carboxyl group) that stabilizes particle dispersion in the ink.

[0188] -Metal Complex-

[0189] The metal complex preferably contains at least one selected from the group consisting of zirconium, aluminum, and titanium as a metal element.

[0190] The metal complex is preferably a metal complex containing at least one selected from the group consisting of acetate, acetylacetone, methyl acetoacetate, ethyl acetoacetate, octanediol, butoxyacetylacetone, lactate, lactate ammonium salt, and triethanolamine as a ligand.

[0191] The metal complex can be a commercially available product. Various organic ligands (especially various multidentate ligands capable of forming metal chelate catalysts) are commercially available. Therefore, the metal complex can be a metal complex prepared by combining commercially available organic ligands and metals.

[0192] 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 monoethyl acetoacetate (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.), titanium diisopropoxybis(acetylacetonate) (e.g., “ORGATIX TC-100” manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium tetraacetylacetonate (e.g., “ORGATIX TC-401”), dioctyloxybis(octanediol)titanium (e.g., “ORGATIX TC-200” manufactured by Matsumoto Fine Chemical Co., Ltd.), diisopropoxybis(ethyl acetoacetate)titanium (e.g., “ORGATIX TC-750” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium tetraacetylacetonate (e.g., “ORGATIX ZC-700” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium tributoxymonoacetylacetonate (e.g., “ORGATIX ZC-540” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium monobutoxyacetylacetonate bis(ethyl acetoacetate) (e.g., “ORGATIX ZC-570” manufactured by Matsumoto Fine Chemical Co., Ltd.), dibutoxybis(ethyl acetoacetate)zirconium (e.g., “ORGATIX ZC-580”), aluminum triacetylacetonate (e.g., “ORGATIX AL-80” manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium ammonium lactate (e.g., “ORGATIX TC-300” manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium lactate (e.g.,, Ltd. "ORGATIX TC-310, 315"), triethanolamine titanium (Matsumoto Fine Chemical Co., Ltd. "ORGATIX TC-400"), and zirconium chloride compounds (for example, Matsumoto Fine Chemical Co., Ltd. "ORGATIX ZC-126").

[0193] Among them, the metal complex is preferably titanium ammonium lactate (for example, "ORGATIX TC-300" manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium lactate (for example, "ORGATIX TC-310, 315" manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium triethanolamine (for example, "ORGATIX TC-400" manufactured by Matsumoto Fine Chemical Co., Ltd.) or a zirconium chloride compound (for example, "ORGATIX ZC-126" manufactured by Matsumoto Fine Chemical Co., Ltd.).

[0194] -Cationic polymer-

[0195] Furthermore, the pretreatment liquid may contain one or more cationic polymers as coagulant components. The cationic polymer is preferably a homopolymer of a cationic monomer having primary or tertiary amino groups or a quaternary ammonium base, or a copolymer or polycondensate 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.

[0196] Examples of the cationic polymer include polyvinyl pyridinium salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, polyvinylimidazoles, polyethyleneimines, polybiguanides, polyguanidines, polyallylamines, and derivatives thereof.

[0197] From the perspective of the viscosity of the pretreatment liquid, the weight-average molecular weight of the cationic polymer is preferably relatively low. When the pretreatment liquid is applied to the recording medium by inkjet recording, 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 greater is advantageous from the perspective of aggregation speed. A weight-average molecular weight of 500,000 or less is advantageous from the perspective of ejection reliability. However, this is not limited to the case where the pretreatment liquid is applied to the recording medium by methods other than inkjet recording.

[0198] The coagulant contained in the pretreatment liquid may be only one kind or two or more kinds.

[0199] The content of the coagulant is preferably 0.1 to 40% by mass, more preferably 0.1 to 30% by mass, further preferably 1 to 20% by mass, and particularly preferably 1 to 10% by mass, relative to the total amount of the pretreatment liquid.

[0200] (water)

[0201] The pre-treatment liquid in the ink set of the present invention preferably contains water. The water content is not particularly limited, and is, for example, 50% to 90% by mass.

[0202] (Organic Solvent)

[0203] The pre-treatment liquid in the ink set of the present invention preferably contains an organic solvent. The organic solvent contained in the pre-treatment liquid may be one kind or two or more kinds.

[0204] From the viewpoint of spraying stability and lamination strength, the organic solvent preferably contains an organic solvent having a boiling point lower than 200°C, and more preferably contains an organic solvent having a boiling point of 120°C to 200°C.

[0205] The content of the organic solvent having 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 pretreatment liquid. In other words, the pretreatment liquid preferably does not contain an organic solvent having a boiling point of 200°C or higher. If the pretreatment liquid contains an organic solvent, the organic solvent preferably has a boiling point below 200°C.

[0206] 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.

[0207] Examples of the organic solvent having a boiling point lower than 200° C. include the organic solvents listed above in the section on the organic solvent contained in the ink.

[0208] 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.

[0209] (Other ingredients)

[0210] The pretreatment liquid may contain other components besides the resin, coagulant, and water as needed. Examples of other components that may be contained in the pretreatment liquid include surfactants, solid wetting agents, colloidal silica, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, mildew inhibitors, 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 Japanese Patent Application Laid-Open No. 2013-001854).

[0211] (physical properties)

[0212] The equilibrium moisture content of the solids 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, but is, for example, 0.1% by mass. The equilibrium moisture content of the solids of the pretreatment liquid at 25°C and 50% RH is measured using the same method as the equilibrium moisture content of the solids of the ink at 25°C and 50% RH.

[0213] The equilibrium moisture content of the solids of the pretreatment liquid at 25°C and 50% RH is preferably lower than the equilibrium moisture content of the solids of the ink at 25°C and 50% RH. It is believed that water easily enters the pretreatment layer from the non-permeable substrate side during the boiling treatment. Therefore, if the equilibrium moisture content of the solids of the pretreatment liquid at 25°C and 50% RH is low, the lamination strength after the boiling treatment is excellent. Furthermore, the absolute value of the difference between the equilibrium moisture content of the solids of the pretreatment liquid at 25°C and 50% RH and the equilibrium moisture content of the solids 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.

[0214] From the viewpoint of ink aggregation speed, the pH of the pretreatment liquid is preferably 0.1 to 4.5, 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 DKK-TOA CORPORATION (Model "HM-31").

[0215] From the perspective of ink aggregation speed, the viscosity of the pretreatment liquid is preferably 0.5 to 10 mPa·s, more preferably 1 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.

[0216] 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 manufactured by Kyowa Interface Science Co., Ltd. (product name "CBVP-Z"), by the plate method.

[0217] <Image Recording Method>

[0218] The image recording method of the present invention includes: a step of applying a pretreatment liquid to an impermeable substrate (hereinafter referred to as the "pretreatment liquid applying step"); and a step of applying ink to the impermeable substrate to which the pretreatment liquid has been applied to record an image using an inkjet recording method (hereinafter referred to as the "image recording step").

[0219] (Pretreatment liquid application step)

[0220] In the pretreatment liquid applying step, the pretreatment liquid is applied to the non-permeable substrate.

[0221] -Impermeable substrate-

[0222] In the present invention, the impermeability of an impermeable substrate refers to a water absorption rate of 2.5% or less within 24 hours, as measured in accordance with ASTM D570-98 (2018). The unit "%" used for water absorption is based on mass. The water absorption rate is preferably 1.0% or less, and more preferably 0.5% or less.

[0223] Examples of materials for the non-permeable 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.).

[0224] The material of the impermeable substrate is preferably resin.

[0225] Among them, from the viewpoint of versatility, the material of the impermeable substrate is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0226] The shape of the impermeable substrate is preferably a sheet (film) or plate. Examples of such impermeable substrates include glass plates, metal plates, resin sheets (resin films), plastic-laminated paper, metal-laminated or vapor-deposited paper, and metal-laminated or vapor-deposited plastic sheets (plastic films).

[0227] Examples of the resin-made impermeable substrate include resin sheets (resin films), and specifically, flexible packaging materials for packaging food and the like, and floor guides for large retail stores.

[0228] Examples of the impermeable substrate include sheet-shaped (film-shaped) or plate-shaped impermeable substrates and textiles (woven fabrics) and nonwoven fabrics formed of impermeable fibers.

[0229] 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.

[0230] The non-permeable substrate may be subjected to a hydrophilic treatment. Examples of hydrophilic treatments include, but are not limited to, corona treatment, plasma treatment, heat treatment, abrasion treatment, light irradiation treatment (e.g., UV treatment), and flame treatment. Corona treatment can be performed, for example, using a corona master (product name "PS-10S," manufactured by Shinko Electric & Instrumentation Co., Ltd.). The conditions for the corona treatment can be appropriately selected depending on the type of the non-permeable substrate.

[0231] The impermeable substrate may be heated before applying the pretreatment liquid. The heating temperature can be appropriately set depending on the type of the impermeable substrate, but is preferably set to 30°C to 70°C, more preferably 30°C to 60°C.

[0232] -Method of applying pretreatment liquid-

[0233] 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.

[0234] Examples of the coating method include known coating methods using a bar coater, an extrusion die coater, an air knife coater, a blade coater, a rod coater, a knife coater, an extrusion coater, a reverse roll coater, and the like.

[0235] The ink jetting method in the inkjet recording method is not particularly limited and can be any of the well-known methods, for example, a charge control method that utilizes electrostatic attraction to jet ink, a drop-on-demand inkjet method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into a sound beam and irradiates the ink, and utilizes radiation pressure to jet the ink, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and utilizes the generated pressure.

[0236] As an inkjet recording method, the method described in Japanese Patent Application Laid-Open No. 54-59936 can be particularly effectively utilized. In this inkjet recording method, the ink undergoes a rapid volume change due to thermal energy, and the force generated by this state change causes the ink to be ejected from a nozzle. Another applicable inkjet recording method is the method described in paragraphs 0093 to 0105 of Japanese Patent Application Laid-Open No. 2003-306623.

[0237] When an inkjet recording method is used, the pretreatment liquid is applied to the non-permeable substrate by ejecting the pretreatment liquid from the nozzles of an inkjet head.

[0238] As inkjet head methods, there are a reciprocating method in which a short serial inkjet head records while scanning in the width direction of the recording medium, and a line method in which a line inkjet head is used in which recording elements are arranged corresponding to the entire area of one side of the recording medium.

[0239] The line method scans the recording medium in a direction intersecting the arrangement of the recording elements, enabling image recording across the entire surface of the recording medium. The line method eliminates the need for a carriage or other transport system, such as the one used in the reciprocating method to scan the short strips of inkjet heads. Furthermore, compared to the reciprocating method, the line method eliminates the need for complex scanning control between the carriage and the recording medium; only the recording medium is moved. Therefore, the line method can increase image recording speed compared to the reciprocating method.

[0240] The application of the pretreatment liquid is preferably performed using an inkjet head having a resolution of 300 dpi or higher (more preferably 600 dpi or higher, and even more preferably 800 dpi or higher). Dpi is an abbreviation for dots per inch, and 1 inch is 2.54 cm.

[0241] From the viewpoint of obtaining a high-definition image, 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.

[0242] (Image Recording Process)

[0243] In the image recording step, an inkjet recording method is used to apply ink to the non-permeable substrate to which the pre-treatment liquid has been applied, thereby recording an image. Details of the inkjet recording method are the same as those of the inkjet recording method for applying the pre-treatment liquid.

[0244] (Other processes)

[0245] The image recording method of the present invention may include other steps besides the pre-treatment liquid applying step and the image recording step.

[0246] The pretreatment liquid applied to the non-permeable substrate may be dried by heating after application. Examples of the mechanism for drying the pretreatment liquid by heating include known heating mechanisms such as heaters, known air supply mechanisms such as dryers, and combinations thereof.

[0247] Examples of methods for heat-drying the pretreatment liquid include a method of heating the non-permeable substrate from the side opposite to the side to which the pretreatment liquid is applied using a heater, a method of blowing warm air or hot air toward the side to which the pretreatment liquid is applied, a method of heating the non-permeable substrate from the side to which the pretreatment liquid is applied or from the side opposite to the side to which the pretreatment liquid is applied using an infrared heater, and a method of combining a plurality of these methods.

[0248] The heating temperature during heat drying of the pretreatment liquid is preferably 35° C. or higher, more preferably 40° C. or higher. The upper limit of the heating temperature is not particularly limited, but is preferably 100° C., more preferably 90° C., and even more preferably 70° C.

[0249] The heating drying time is not particularly limited, but is preferably 0.5 to 60 seconds, more preferably 0.5 to 20 seconds, and even more preferably 0.5 to 10 seconds.

[0250] [Method for producing laminate]

[0251] A method for producing a laminate as one embodiment of the present invention includes: a step of obtaining an image recorded article comprising an impermeable substrate and an image arranged on the impermeable substrate by the image recording method of the present invention; and a step of laminating a laminating substrate on a side of the image recorded article on which the image is arranged to obtain a laminate.

[0252] The image recording method using the ink set of the present invention can produce an image recorded material comprising an impermeable substrate and an image recorded on the impermeable substrate, wherein a laminating substrate is laminated on the image and exhibits excellent lamination strength after boiling treatment.

[0253] Therefore, the image recording method using the ink set of the present invention is suitable for producing a laminate comprising the above-mentioned image recorded matter and a laminating substrate laminated on the image-recorded side of the image recorded matter.

[0254] According to the method for producing a laminated body as one embodiment of the present invention, a laminated body having excellent lamination strength between the image recorded material and the lamination substrate can be produced even when a boiling treatment is performed.

[0255] Regarding the process of obtaining an image recorded object, reference can be made to the above-mentioned image recording method of the present invention.

[0256] The step of obtaining a laminate is to laminate a laminating substrate onto the image-disposed side of the image recorded article. Lamination can be performed by, for example, laminating the laminating substrate onto the image-disposed side of the image recorded article via another layer (e.g., an adhesive layer) or by laminating the laminating substrate onto the image-disposed side of the image recorded article using a laminator. In the latter case, a commercially available laminator can be used.

[0257] The lamination temperature during lamination is not particularly limited. For example, when the image recorded material and the lamination substrate are attached via another layer (e.g., an adhesive layer), the lamination temperature can be set at or above 20°C. Furthermore, when using a laminator, the lamination roller temperature can be set within a range of 20°C to 80°C. The contact force of the lamination roller pair can be appropriately selected as needed.

[0258] The lamination substrate is preferably a resin substrate. The resin substrate is not particularly limited, and examples thereof include substrates made of thermoplastic resins.

[0259] Examples of the resin substrate include a substrate obtained by molding a thermoplastic resin into a sheet shape.

[0260] The resin substrate preferably contains polypropylene, polyethylene terephthalate, nylon, polyethylene, or polyimide.

[0261] The shape of the resin substrate is not particularly limited, but a sheet-shaped resin substrate is preferred. The thickness of the resin substrate is preferably 10 μm to 200 μm, more preferably 10 μm to 100 μm.

[0262] In the step of obtaining the laminate, the laminating substrate may be laminated directly on the image-disposed side of the image recorded material or may be laminated via another layer (eg, an adhesive layer) thereon.

[0263] When the laminating substrate is directly laminated on the side of the image recorded material on which the image is arranged, lamination can be performed by a known method such as thermocompression bonding or thermal fusion bonding.

[0264] Furthermore, lamination in the case of laminating the laminating substrate via an adhesive layer onto the image-disposed side of the image recorded material can be carried out, for example, by applying an adhesive onto the image-disposed side of the image recorded material, placing the laminating substrate thereon, and then bonding the image recorded material and the laminating substrate together.

[0265] Furthermore, lamination on the side of the image recorded material on which the image is arranged via an adhesive layer can also be performed by a method such as extrusion lamination (ie, sandwich lamination).

[0266] 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 thus the lamination strength can be further increased.

[0267] [Visual Records]

[0268] An image recorded article according to one embodiment of the present invention comprises 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 pretreatment layer has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% relative humidity, and the ink layer has an equilibrium moisture content of 3.0% by mass or less at 25°C and 50% relative humidity.

[0269] A laminate obtained by laminating a laminating substrate on an image recorded material as one embodiment of the present invention has excellent lamination strength when subjected to a boiling treatment.

[0270] Preferred embodiments of the components in the image recorded material are the same as those described in the ink set of the present invention.

[0271] [Laminate]

[0272] A laminate as one embodiment of the present invention includes: the image recorded material of the present invention; and a laminating substrate laminated on the image recorded material.

[0273] The laminated body as one embodiment of the present invention has excellent lamination strength when subjected to a boiling treatment.

[0274] In the laminate, the laminating substrate may be laminated directly on the side of the image recorded material where the image is arranged, or may be laminated via another layer (adhesive layer) on the side of the image recorded material where the image is arranged.

[0275] The laminate of the present invention is preferably produced by the method for producing a laminate of the present invention.

[0276] Preferred embodiments of the lamination substrate and the adhesive layer are the same as those described in the section of the method for producing the laminate.

[0277] Example

[0278] Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following Examples unless it departs from the gist of the present invention.

[0279] <Preparation of Pretreatment Liquid>

[0280] The following ingredients were mixed in the following amounts to prepare a pretreatment solution.

[0281] Coagulant: Glutaric acid…4.1% by mass

[0282] Resin emulsion described in Table 1 or Table 2 ... 6 mass % (content calculated as resin particles as solid content)

[0283] Propylene glycol…10% by mass

[0284] Water…79.9% by mass

[0285] <Preparation of ink>

[0286] When preparing ink, first, a pigment dispersion is prepared.

[0287] (Preparation of Pigment Dispersion 1)

[0288] -Synthesis of uncrosslinked resin-

[0289] A monomer supply composition was prepared by mixing methacrylic acid (200 parts by mass), benzyl methacrylate (80 parts by mass), and isopropyl alcohol (375 parts by mass). Furthermore, an initiator supply composition was prepared by mixing 2,2-azobis(2-methylbutyronitrile) (22.05 parts by mass) and isopropyl alcohol (187.5 parts by mass).

[0290] Next, isopropyl alcohol (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 over 2 hours. After the addition was completed, the resulting solution was further maintained at 80°C for 4 hours and then cooled to 25°C.

[0291] 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.

[0292] - Cross-linking treatment -

[0293] After neutralizing 0.8 equivalents of methacrylic acid in the obtained uncrosslinked resin (150 parts by mass) with an aqueous potassium hydroxide solution, water was further added to adjust the concentration of the neutralized uncrosslinked resin to 25% by mass to obtain an aqueous solution of the neutralized uncrosslinked resin.

[0294] A neutralized aqueous solution of the uncrosslinked resin (50 parts by mass), CI Pigment Blue 15:3 (cyan pigment) (50 parts by mass), water (190 parts by mass), and dipropylene glycol (30 parts by mass) were mixed and dispersed using a bead mill (bead diameter 0.1 mmφ, zirconia beads) to obtain a dispersion in which the cyan pigment was dispersed in the uncrosslinked resin (uncrosslinked dispersion). The cyan pigment concentration was 15% by mass.

[0295] 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 an aqueous boric acid solution (boric acid concentration: 4% by mass) (14.3 parts) were added. The mixture was semi-reacted at 50°C for 6 hours and then cooled to 25°C. The uncrosslinked resin was thereby crosslinked by the crosslinking agent. This resulted in a dispersion (crosslinked dispersion) in which the cyan pigment was dispersed in crosslinked resin 1. Note that crosslinked resin 1 is a crosslinked product of the uncrosslinked resin. Water was then added to the resulting crosslinked dispersion, and ultrafiltration was performed using a stirring ULTRAHOLDER (manufactured by ADVANTEC CO., LTD.) and an ultrafiltration filter (manufactured by ADVANTEC CO., LTD., molecular weight cutoff 50,000, Q0500076E ULTRAFILTER). After purification to reduce the dipropylene glycol concentration in the crosslinked dispersion to 0.1 mass % or less, the dispersion was concentrated to a pigment concentration of 15 mass %, thereby obtaining a dispersion in which the cyan pigment was dispersed in the crosslinked resin 1 (cyan pigment concentration 15 mass %).

[0296] In the pigment dispersion 1 , at least a portion of the surface of the cyan pigment is covered with the cross-linked resin 1 .

[0297] The acid value of the crosslinked resin 1 was 60 mgKOH / g.

[0298] (Preparation of Pigment Dispersion Liquid 2)

[0299] Pigment Dispersion 2 was obtained by the same method as that for Pigment Dispersion 1, except that the amount of the potassium hydroxide aqueous solution and the amount of the crosslinking agent in the preparation of Pigment Dispersion 1 were changed so that the acid value of the crosslinked resin became 36 mgKOH / g.

[0300] In the pigment dispersion 2 , at least a portion of the surface of the cyan pigment is covered with the cross-linked resin 2 .

[0301] The acid value of the cross-linked resin 2 was 36 mgKOH / g.

[0302] (Preparation of Pigment Dispersion 3)

[0303] Pigment dispersion 3 was obtained by the same method as pigment dispersion 1 except that 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.

[0304] In the pigment dispersion 3 , at least a portion of the surface of the cyan pigment is covered with the cross-linked resin 3 .

[0305] The acid value of the crosslinked resin 3 was 100 mgKOH / g.

[0306] (Preparation of ink)

[0307] The following components were added to the prepared pigment dispersion to prepare inks. In Example 15, pigment dispersion 2 was used, and in Example 16, pigment dispersion 3 was used. In the other examples and comparative examples, pigment dispersion 1 was used.

[0308] Pigment dispersion: Amount such that the pigment concentration becomes 4% by mass

[0309] Resin particles listed in Table 1 or Table 2: The amount of resin particles listed in Table 1 or Table 2 as a solid content.

[0310] Propylene glycol…20% by mass

[0311] Propylene glycol monomethyl ether…5% by mass

[0312] Surfactant: OLFINE E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) ... 1% by mass

[0313] Water: The remainder is such that the entire ink becomes 100% by mass.

[0314] The 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 the resin type column in Tables 1 and 2, styrene acrylic resin is simply referred to as "acrylic resin."

[0315] Neocryl A-1105: Acrylic resin emulsion, manufactured by DSM Japan KK

[0316] Neocryl XK-110: Styrene acrylic resin emulsion, manufactured by DSM Japan KK

[0317] VINYBLAN 715: Vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0318] Neocryl XK-555: Acrylic resin emulsion, manufactured by DSM Japan KK

[0319] HIROS M-141: Acrylic resin emulsion, manufactured by SEIKO PMC CORPORATION

[0320] NeoRez R-4000: Urethane resin emulsion, manufactured by DSM Japan KK

[0321] Neocryl A-1091: Styrene acrylic resin emulsion, manufactured by DSM Japan KK

[0322] Neocryl A-2091: Styrene acrylic resin emulsion, manufactured by DSM Japan KK

[0323] HIROS QE-1042: Styrene acrylic resin emulsion, manufactured by SEIKO PMC CORPORATION

[0324] Neocryl A-1092: Styrene acrylic resin emulsion, manufactured by DSM Japan KK

[0325] VINYBLAN 2687: Acrylic resin emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0326] Neocryl XK-88: Styrene acrylic resin emulsion, manufactured by DSM Japan KK

[0327] SUPERFLEX 620: Urethane resin emulsion, manufactured by DKS Co. Ltd.

[0328] AUROREN AE-202: Olefin resin emulsion, manufactured by NIPPON PAPER INDUSTRIES CO., LTD.

[0329] JONCRYL 61J: Water-soluble styrene acrylic resin, manufactured by BASF

[0330] Mowinyl 972: Styrene acrylic resin emulsion, manufactured by Japan Coating Resin Co., Ltd.

[0331] VINYBLAN 711: Vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0332] VINYBLAN A70J9: Vinyl acetate emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0333] CHALINE R-170S: Acrylic silicone resin emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0334] VINYBLAN 1129: Vinyl acetate emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0335] SUPERFLEX 650: Urethane resin emulsion, manufactured by DKS Co. Ltd.

[0336] SUPERFLEX 500M: Urethane resin emulsion, manufactured by DKS Co. Ltd.

[0337] PERMARIN UC-20: Urethane resin emulsion, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.

[0338] Mowinyl 7720: Acrylic resin emulsion, manufactured by Japan Coating Resin Co., Ltd.

[0339] ACRIT UW-550CS: Acrylic resin emulsion, manufactured by TAISEI FINE CHEMICAL CO., LTD.

[0340] NS313X: Urethane resin emulsion, manufactured by TAKAMATSU OIL&FAT CO., LTD.

[0341] PLAS COAT Z-446: Water-soluble polyester resin, manufactured by GOO CHEMICAL CO., LTD.

[0342] Hardlen EW-5313: Olefin resin emulsion, manufactured by TOYOBO CO., LTD.

[0343] JONCRYL 537: Acrylic resin emulsion, manufactured by BASF

[0344] VINYBLAN 700: Vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0345] VINYBLAN 701: Vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd.

[0346] JONCRYL PDX-7700: Styrene acrylic resin emulsion, manufactured by BASF

[0347] JONCRYL 840: Acrylic resin emulsion, manufactured by BASF

[0348] [Image Record]

[0349] Image recording was performed using the prepared pretreatment liquid and ink.

[0350] An inkjet recording apparatus was prepared that included a conveying system for continuously conveying a long substrate, a wire bar coater for applying a pretreatment liquid onto the substrate, and an inkjet head for applying ink onto the surface of the substrate to which the pretreatment liquid had been applied.

[0351] Furthermore, a polyethylene terephthalate (PET) substrate ("FE2001" manufactured by FUTAMURA CHEMICAL CO., LTD. (thickness 25 μm, width 500 mm, length 2000 m); hereinafter referred to as "impermeable substrate A") was prepared as an impermeable substrate.

[0352] Using an inkjet recording apparatus, a cyan solid image was recorded as follows while the non-permeable substrate A was continuously conveyed at 635 mm / sec.

[0353] The pretreatment solution was applied to the non-permeable substrate A using a wire rod coater to a thickness of about 1.7 g / m 2 , followed by drying at 50°C for 2 seconds.

[0354] Next, the ink was applied to the surface of the non-permeable substrate A coated with the pretreatment liquid in a solid image under the following application conditions, and the applied ink was dried at 80° C. for 30 seconds to record a solid image.

[0355] The drying method of the pretreatment liquid and the drying method of the ink were both set to warm air drying.

[0356] -Ink application conditions-

[0357] Inkjet head: Piezoelectric full-line inkjet head with a width of 1200dpi / 20inch

[0358] Ink ejection volume from inkjet head: 4.0pL

[0359] Drive frequency: 30kHz (substrate conveying speed: 635mm / s)

[0360] [evaluate]

[0361] The lamination strength, lamination strength after boiling treatment, and character quality of the image records were evaluated for each Example and Comparative Example. The evaluation methods are as follows. The evaluation results are shown in Tables 1 and 2.

[0362] (Lamination Strength)

[0363] According to the above-described image recording, an image recorded material having a solid image recorded on the non-permeable substrate A is obtained.

[0364] A region of 500 mm in length and 500 mm in width (hereinafter also referred to as a lamination strength evaluation region) having a solid image provided on the entire surface was cut out from the image recorded material to prepare a lamination strength evaluation sample.

[0365] A dry lamination adhesive (main agent TM-320 (isocyanate compound) / curing agent CAT-13B (alcohol compound), manufactured by Toyo-Morton, Ltd.) was applied to the solid image of the lamination strength evaluation sample using a bar coater. A linear low-density polyethylene film (trade name "LL-XMTN," manufactured by FUTAMURA CHEMICAL CO., LTD., 40 μm thick) was then laminated on top as a lamination substrate. In this state, the lamination substrate and the lamination strength evaluation sample were bonded together to form a laminate.

[0366] The obtained laminate was aged at 40°C for 48 hours.

[0367] A sample piece having a length of 100 mm and a width of 15 mm was cut out from the aged laminate.

[0368] Next, the laminating substrate and the lamination strength evaluation sample were peeled off by hand in an area 30 mm long from one longitudinal end of the sample sheet, while the laminating substrate and the lamination strength evaluation sample remained attached to the remaining 70 mm long area.

[0369] Next, a tensile test was performed by pulling the peeled portion of the sample sheet, the laminating substrate, and the peeled portion of the lamination strength evaluation sample in opposite directions. The pulling direction was perpendicular to the remaining 70 mm length (the area left to maintain the laminating substrate and the lamination strength evaluation sample in contact).

[0370] The tensile test was performed to determine the peel strength of the laminate substrate and the laminate strength evaluation sample after peeling the remaining 70 mm length. The obtained peel strength was used as the laminate strength. The evaluation criteria were as follows. The evaluation results are shown in Tables 1 and 2.

[0371] The tensile test was performed using a tensile testing machine (product name: "TENSILON RTM-25", manufactured by Orientec Co., Ltd.).

[0372] 5: The lamination strength between the image recorded material and the lamination substrate is 2 N / 15 mm or more.

[0373] 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.

[0374] 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.

[0375] 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.

[0376] 1: The lamination strength between the image recorded material and the laminating substrate is less than 0.5 N / 15 mm.

[0377] (Lamination strength after boiling treatment)

[0378] A laminate was produced by the same method as the laminate production method described in the above-mentioned evaluation method of lamination strength.

[0379] The obtained laminate was aged at 40°C for 48 hours.

[0380] The aged laminate was boiled at 95° C. for 40 minutes using a retort autoclave (small sterilizer) (product name “SR-240”, manufactured by TOMY SEIKO CO., LTD.).

[0381] A sample piece having a length of 100 mm and a width of 15 mm was cut out from the laminate after the boiling treatment.

[0382] Next, the sample pieces were subjected to a tensile test using the same method as described in the above-mentioned method for evaluating lamination strength to determine the peel strength. The obtained peel strength was used as the lamination strength. The evaluation criteria were as follows. The evaluation results are shown in Tables 1 and 2.

[0383] 5: The lamination strength between the image recorded material and the lamination substrate after the boiling treatment is 2 N / 15 mm or more.

[0384] 4: The lamination strength between the image recorded material and the laminating substrate after the boiling treatment is 1.5 N / 15 mm or more and less than 2 N / 15 mm.

[0385] 3: The lamination strength between the image recorded material and the lamination substrate after the boiling treatment is 1 N / 15 mm or more and less than 1.5 N / 15 mm.

[0386] 2: The lamination strength between the image recorded material and the lamination substrate after the boiling treatment is 0.5 N / 15 mm or more and less than 1 N / 15 mm.

[0387] 1: The lamination strength between the image recorded material and the laminating substrate after the boiling treatment is less than 0.5 N / 15 mm.

[0388] (Character quality)

[0389] By the same method as the above-mentioned image recording, an image record having a character image recorded on the non-permeable substrate A was obtained. As the character image, 4pt, 6pt, 8pt and 10pt were printed. Figure 1 The characters shown are (Unicode: U+9DF9). Here, pt represents DTP point, which represents the font size, and 1pt is 1 / 72 inch.

[0390] The character quality was evaluated by observing each character image on the image record and judging whether it could be reproduced. "Reproducible" means that when checked from a distance of 0.5 m, Figure 1 In the character image, Figure 1 The horizontal line represented by 11 is the same as the horizontal line represented by Figure 1 The horizontal lines indicated by 12 are separated. The evaluation criteria are as follows.

[0391] The evaluation results are shown in Tables 1 and 2.

[0392] 5: 4pt characters are reproduced.

[0393] 4: 6pt characters are reproduced, but 4pt characters are not.

[0394] 3: 8pt characters were reproduced, but characters under 6pt were not reproduced.

[0395] 2: 10pt characters were reproduced, but characters under 8pt were not reproduced.

[0396] 1: Unable to reproduce 10pt characters.

[0397] 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.

[0398] The pretreatment liquid and ink were each placed in a 60°C thermostat for 24 hours. Furthermore, they were vacuum-dried at 60°C for 3 hours using a vacuum thermostat dryer (product name "DRV420DA", manufactured by ADVANTEC CO., LTD.) to obtain solid substances of the pretreatment liquid and ink, respectively. The solid substances were then placed in a 25°C, 50% RH thermostat for 24 hours. After 24 hours, the moisture content of the solid substances was measured using a moisture vaporization method using a trace moisture analyzer (product name "CA-200", manufactured by Mitsubishi Chemical Analytech 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 for the anolyte, and a coulometric titration reagent (product name "AQUAMICRON Cx U", manufactured by Mitsubishi Chemical Corporation) was used for the catholyte.

[0399] Tables 1 and 2 describe the equilibrium moisture content of the pretreatment liquid at 25°C and 50% RH for the coagulant, resin, and solid components contained in the pretreatment liquid. The ink describes the equilibrium moisture content of the resin and solid components contained in the ink at 25°C and 50% RH. The resins contained in the ink are 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 greater. In Tables 1 and 2, the unit of acid value is omitted and expressed as "mgKOH / g." Furthermore, "Resin Particles A / Resin Particles B" in Tables 1 and 2 represents the mass ratio of the content of Resin Particles A to the content of Resin Particles B. In the case where a component listed in a column is not present, "-" is indicated. As mentioned above, JONCRYL 61J and PLAS COAT Z-446 are water-soluble resins, but are listed in the resin particle column.

[0400]

[0401]

[0402] As shown in Table 1, in Examples 1 to 19, the pretreatment liquid contained a resin and water, and the ink contained a pigment, a resin, and water. 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 can be seen that the lamination strength after the boiling treatment is excellent.

[0403] 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 component of the pretreatment liquid at 25°C and 50% RH and the equilibrium moisture content of the solid component of the ink at 25°C and 50% RH exceeded 3.0% by mass, indicating that the lamination strength after the boiling treatment was poor.

[0404] In Example 2, the equilibrium moisture content of the solid content of the ink at 25° C. and 50% RH was 1.5% by mass or less, and therefore, it was found that the lamination strength after the boiling treatment was superior to that of Examples 3 to 6.

[0405] In Example 10, the ink contains 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. Therefore, it is found that the character quality is superior to that of Example 2.

[0406] In Examples 11 to 13, Example 15, and Example 16, 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. Therefore, it can be seen that compared with Example 10 and Example 14, the lamination strength, lamination strength after boiling treatment, and character quality are all excellent.

[0407] In Example 17, the resin contained in the pretreatment liquid and the resin contained in the ink were both acrylic resins. Therefore, it was found that the lamination strength and the lamination strength after the boiling treatment were superior to those of Examples 18 and 19.

[0408] In addition, the entire contents of Japanese Patent Application No. 2021-015957 filed on February 3, 2021 are incorporated herein by reference. Furthermore, all documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, or technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. An inkjet ink set for non-permeable substrates, comprising: a pretreatment fluid comprising resin and water; and Ink, containing pigment, resin and water, 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. The resin contained in the pretreatment liquid and the resin contained in the ink are acrylic resin or urethane resin, respectively.

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 ink includes resin particles.

4. The inkjet ink set for non-permeable substrates according to claim 1 or 2, wherein: 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.

5. The inkjet ink set for non-permeable substrates according to claim 4, wherein: The mass ratio of the content of the resin particles having an acid value of less than 30 mgKOH / g to the 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 claim 1 or 2, wherein: The equilibrium moisture content of the solid content of the ink at 25° C. and 50% RH is 1.5% by mass or less.

7. The inkjet ink set for non-permeable substrates according to claim 1 or 2, wherein: 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.

8. The inkjet ink set for non-permeable substrates according to claim 1 or 2, wherein: The pretreatment liquid contains a coagulant.

9. An image recording method using the inkjet ink set for non-permeable substrates according to any one of claims 1 to 8, The image recording method comprises: The process of applying the pretreatment liquid to the non-permeable substrate; and A process of recording an image by applying the ink to the non-permeable substrate to which the pre-treatment liquid has been applied using an inkjet recording method.

10. A method for manufacturing a laminate, comprising: a step of obtaining an image recorded article comprising the impermeable substrate and an image disposed on the impermeable substrate by the image recording method according to claim 9; and A step of laminating a laminating substrate on the side of the image recorded material on which the image is arranged to obtain a laminate.

11. An image recorded material comprising an impermeable substrate and an image disposed on the impermeable substrate. The image includes: a pretreatment layer disposed on the non-permeable substrate and containing a resin; and an ink layer disposed on the pre-treated layer and containing a pigment and a resin, 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. The resin contained in the pretreatment layer and the resin contained in the ink are acrylic resin or urethane resin, respectively.

12. The image recorded material according to claim 11, wherein The pretreatment layer contains a coagulant.

13. A laminate comprising: The image record according to claim 11; and A laminating substrate is laminated on the image of the image recorded material.

Images