Ink-jet ink for impermeable substrates, ink set, image recording method, and method for producing laminate

Abstract

Provided is an ink-jet ink for impermeable substrates which, when imparted to an impermeable substrate to record an image thereon and obtain an image-bearing object and when a laminating substrate is laminated to the image of the obtained image-bearing object, enables the obtained laminate to have improved retort resistance.

Description

Inkjet ink for non-permeable substrate, ink set, image recording method, and method for manufacturing laminated body

[0001] The present disclosure relates to inkjet inks for non-permeable substrates, ink sets, image recording methods, and methods for producing laminates.

[0002] In recent years, studies have been conducted on techniques for recording images using inkjet inks on non-permeable substrates (also called non-absorbent recording media, etc.) such as polyolefin substrates, polyethylene terephthalate substrates, etc. For example, Patent Literature 1 discloses an inkjet ink containing two specific types of urethane resin particles, which can be used for recording images on non-absorbent recording media, etc., and can provide image recordings that are excellent in abrasion resistance, gloss, laminate peel resistance, and blocking resistance.

[0003] Patent Document 1: JP 2021-102693 A

[0004] In some cases, an inkjet ink is applied to an impermeable substrate to record an image, thereby obtaining an image recording material, and a laminating substrate is laminated onto the image in the obtained image recording material to produce a laminate. Retort resistance may be required for the obtained laminate. Here, retort resistance refers to resistance to heat and pressure sterilization at a temperature of 100°C or higher. Retort resistance is distinguished from boiling resistance, which is resistance to hot water sterilization at a temperature below 100°C, in that it is resistance to heat and pressure sterilization at a temperature of 100°C or higher. Retort resistance is resistance to treatment under more severe temperature and pressure conditions than boiling resistance.

[0005]

[0010] An object of one embodiment of the present disclosure is to provide an inkjet ink that can improve the retort resistance of a laminated body produced by applying the inkjet ink to a non-permeable substrate to record an image, and laminating a laminating substrate onto the image in the obtained image recorded body. Another object of another embodiment of the present disclosure is to provide an ink set including the inkjet ink, and an image recording method and a method for producing a laminated body using the inkjet ink.

[0006] The present disclosure includes the following aspects: <1> An inkjet ink for non-penetrable substrates, comprising water, a pigment, a pigment dispersion resin, and resin particles, wherein the pigment dispersion resin comprises a first urethane resin and the resin particles comprise a second urethane resin. <2> The inkjet ink for non-penetrable substrates according to <1>, wherein the proportion of the urethane resin in the total resin components contained is 80 mass % or more. <3> The inkjet ink for non-penetrable substrates according to <1> or <2>, wherein both the first urethane resin and the second urethane resin contain polyol units A, which are at least one type of polyol units containing no acid groups. <4> The inkjet ink for non-penetrable substrates according to <3>, wherein the proportion of the polyol units A in the polyol units containing no acid groups contained in the first urethane resin is 60 mol % or more. <5> The inkjet ink for non-penetrable substrates according to <3> or <4>, wherein the proportion of the polyol units A in the polyol units containing no acid groups contained in the second urethane resin is 60 mol % or more. <6> The inkjet ink for non-penetrable substrates according to any one of <1> to <5>, wherein the absolute value of the difference between the glass transition temperature of the first urethane resin and the glass transition temperature of the second urethane resin is 40°C or less. <7> The inkjet ink for non-penetrable substrates according to any one of <1> to <6>, wherein the acid value of the first urethane resin is 80 mgKOH / g to 170 mgKOH / g, and the acid value of the second urethane resin is 10 mgKOH / g to 50 mgKOH / g. <8> The inkjet ink for non-penetrable substrates according to any one of <1> to <7>, wherein the acid value is 1.8 mgKOH / g to 4.0 mgKOH / g. <9> An inkset comprising the inkjet ink for non-penetrable substrates according to any one of <1> to <8>, and a pretreatment liquid containing water and a flocculant. <10> The inkset according to <9>, wherein the pretreatment liquid further contains a third urethane resin. <11> The ink set according to <10>, wherein each of the first urethane resin, the second urethane resin, and the third urethane resin contains a polyol unit A that is at least one type of polyol unit that does not contain an acid group.<12> The ink set according to <11>, wherein the proportion of the polyol units A in the polyol units containing no acid group contained in the third urethane resin is 60 mol % or more. <13> An image recording method, using the inkjet ink for non-permeable substrates according to any one of <1> to <8>, comprising a step of applying the inkjet ink for non-permeable substrates onto a non-permeable substrate by an inkjet recording method. <14> An image recording method, using the ink set according to any one of <9> to <12>, comprising a step of applying the pretreatment liquid onto a non-permeable substrate, and a step of applying the inkjet ink for non-permeable substrates onto the non-permeable substrate to which the pretreatment liquid has been applied by an inkjet recording method. <15> A method for producing a laminated body, comprising: a step of obtaining an image recorded matter comprising the impermeable substrate and an image disposed on the impermeable substrate by the image recording method according to <13> or <14>; and a step of laminating a substrate for lamination onto the side of the image recorded matter on which the image is disposed, to obtain a laminated body.

[0007] According to one embodiment of the present disclosure, there is provided an inkjet ink that can improve the retort resistance of a laminated body when a laminated body is produced by applying the inkjet ink to a non-permeable substrate to record an image, and laminating a laminating substrate onto the image in the obtained image recorded body. According to another embodiment of the present disclosure, there is provided an inkset including the inkjet ink, and an image recording method and a method for producing a laminated body using the inkjet ink.

[0008] In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0009] As used herein, the amount of each component in a composition refers to the total amount of the components in the composition unless otherwise specified, when the composition contains multiple substances corresponding to each component. In this specification, a combination of two or more preferred aspects is a more preferred aspect. As used herein, 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 is achieved.

[0010] In this specification, the term "image" refers to a film formed by applying a pretreatment liquid and an ink in this order, and the term "image recording" refers to the formation of an image (i.e., a film). The term "image" in this specification also encompasses a solid image.

[0011] In this specification, the term "(meth)acrylate" encompasses both acrylate and methacrylate, and the term "(meth)acrylic" encompasses both acrylic and methacrylic.

[0012] [Inkjet ink for non-penetrable substrates] The inkjet ink for non-penetrable substrates of the present disclosure (hereinafter also simply referred to as the "ink of the present disclosure") contains water, a pigment, a pigment dispersion resin, and resin particles, wherein the pigment dispersion resin contains a first urethane resin, and the resin particles contain a second urethane resin.

[0013] The ink of the present disclosure is used exclusively for non-permeable substrates. That is, the ink of the present disclosure is an ink used to record images on non-permeable substrates. Details of non-permeable substrates will be described later. In particular, the non-permeable substrate is preferably a resin substrate, and the ink of the present disclosure is preferably for use on a resin substrate.

[0014] In the present disclosure, the first urethane resin refers to the urethane resin contained in the pigment dispersion resin, and the second urethane resin refers to the urethane resin contained in the resin particles. The first urethane resin and the second urethane resin may be the same type of urethane resin or different types of urethane resin. Furthermore, the first urethane resin and the second urethane resin may each be only one type or two or more types.

[0015] The ink of the present disclosure is used in applications in which the inkjet ink is applied to a non-permeable substrate by an inkjet method to record an image, thereby obtaining an image recorded product, and a laminating substrate is laminated onto the image in the obtained image recorded product to produce a laminate. The ink of the present disclosure can improve the retort resistance of the laminate. The reason for this effect is presumed to be as follows.

[0016] As mentioned above, retort resistance refers to resistance to heat-pressure sterilization at temperatures of 100°C or higher. The retort resistance of a laminated body is evaluated by the resistance to laminate lifting (i.e., peeling of the image or laminate substrate) when the laminated body is subjected to retort treatment (i.e., heat-pressure sterilization treatment at temperatures of 100°C or higher). The less laminate lifting occurs, the better the retort resistance of the laminated body. In the ink of the present disclosure, both the pigment dispersion resin and the resin particles in the ink contain urethane resin (i.e., a first urethane resin and a second urethane resin). This increases the ratio of urethane resin to the total resin components in the ink film (i.e., image) formed by the ink, which is thought to result in improved flexibility of the image (i.e., ability to follow deformation of an impermeable substrate). It is thought that improved flexibility of the image makes it less likely for laminate lifting to occur when the laminated body is subjected to retort treatment (i.e., improved retort resistance of the laminated body).

[0017] The ratio of the urethane resin to the total resin components in the ink of the present disclosure (i.e., the total ratio of the first urethane resin and the second urethane resin) is preferably 70% by mass or more, more preferably 80% by mass or more. When the ratio of the urethane resin is 70% by mass or more, the retort resistance of the laminate is further improved.

[0018] Each component that can be contained in the ink will be described below.

[0019] <Water> The ink of the present disclosure contains water. The water content is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 50% by mass or more, relative to the total amount of the ink. The upper limit of the water content relative to the total amount of the ink is determined appropriately depending on the contents of other components, but is, for example, 90% by mass, preferably 85% by mass, and more preferably 80% by mass.

[0020] <Pigment> The ink of the present disclosure contains at least one pigment. The pigment may be an organic pigment or an inorganic pigment.

[0021] Examples of organic pigments include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments or polycyclic pigments are preferred. Examples of azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Examples of dye chelates include basic dye chelates and acid dye chelates.

[0022] Examples of inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black.

[0023] Examples of the pigment include those described in "Dictionary of Pigments" edited by Seijiro Ito (published in 2000), "Industrial Organic Pigments" by W. Herbst and K. Hunger, and JP-A Nos. 2002-12607, 2002-188025, 2003-26978, and 2003-342503.

[0024] The content of the pigment is preferably 1% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 1% by mass to 10% by mass, based on the total amount of the ink.

[0025] <Pigment Dispersion Resin> The ink of the present disclosure contains at least one pigment dispersing resin. The pigment dispersing resin contains at least one first urethane resin.

[0026] The pigment dispersion resin may contain at least one non-urethane resin (i.e., a resin other than a urethane resin; for example, an acrylic resin). Examples of non-urethane resins include acrylic resins. However, from the viewpoint of further improving the retort resistance of the laminate, the proportion of the first urethane resin in the pigment dispersion resin is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, and even more preferably 90% by mass to 100% by mass.

[0027] (First Urethane Resin) The first urethane resin is not particularly limited and may be a known urethane resin (i.e., a resin containing urethane bonds). The first urethane resin may be formed by the reaction of a polyisocyanate with a polyol, similar to known urethane resins. In this case, the first urethane resin may contain polyisocyanate units (i.e., structural units derived from polyisocyanate) and polyol units (i.e., structural units derived from polyol).

[0028] For the polyol and polyisocyanate for forming the first urethane resin, for example, the descriptions in paragraphs 0031 to 0036 of JP 2001-247787 A, the descriptions in paragraphs 0033 to 0118 of WO 2016 / 052053, and the descriptions in paragraphs 0066 to 0223 of WO 2016 / 152254 can be referenced.

[0029] (Polyisocyanate Unit and Polyisocyanate) The first urethane resin may contain at least one polyisocyanate unit. The polyisocyanate for forming the polyisocyanate unit may be a polyisocyanate containing two isocyanate groups (i.e., a diisocyanate (i.e., a bifunctional isocyanate)), or a polyisocyanate containing three or more isocyanate groups (i.e., a trifunctional or higher isocyanate). The polyisocyanate is preferably a bifunctional to hexafunctional isocyanate.

[0030] Examples of bifunctional isocyanates include hexamethylene diisocyanate (abbreviated as HDI), trimethylhexamethylene diisocyanate (abbreviated as TMHDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (abbreviated as XDI), hydrogenated xylylene diisocyanate (abbreviated as HXDI), norbornane diisocyanate (abbreviated as NBDI), diphenylmethane diisocyanate (abbreviated as MDI), hydrogenated diphenylmethane diisocyanate (abbreviated as HMDI), and tolylene diisocyanate (abbreviated as TDI).

[0031] In addition, the bifunctional isocyanate may be a bifunctional isocyanate derived from the above specific examples, such as Duranate (registered trademark) D101, D201, and A101 (manufactured by Asahi Kasei Corporation).

[0032] The tri- or higher functional isocyanate is preferably a reaction product of at least one selected from the group consisting of bifunctional isocyanates and at least one selected from the group consisting of compounds containing three or more active hydrogen groups (e.g., tri- or higher functional polyol compounds, tri- or higher functional polyamine compounds, and tri- or higher functional polythiol compounds). The number of moles (number of molecules) of the bifunctional isocyanate to be reacted with the compound containing three or more active hydrogen groups is preferably 0.6 times or more, more preferably 0.6 to 5 times, even more preferably 0.6 to 3 times, and even more preferably 0.8 to 2 times the number of moles of active hydrogen groups (number of equivalents of active hydrogen groups) in the compound containing three or more active hydrogen groups.

[0033] Examples of the difunctional isocyanate for forming a trifunctional or higher isocyanate include the difunctional isocyanates according to the specific examples described above.

[0034] Examples of compounds containing three or more active hydrogen groups for forming trifunctional or higher isocyanates include the compounds described in paragraphs 0057 to 0058 of WO 2016 / 052053.

[0035] Examples of tri- or higher functional isocyanates include adduct-type tri- or higher functional isocyanates, isocyanurate-type tri- or higher functional isocyanates, biuret-type tri- or higher functional isocyanates, etc. Commercially available adduct-type tri- or higher functional isocyanates include Takenate (registered trademark) D-102, D-103, D-103H, D-103M2, P49-75S, D-110N, D-120N, D-140N, D-160N (all Mitsui Chemicals, Inc.), Desmodur (registered trademark) L75, UL57SP (Sumika Bayer Urethane Co., Ltd.), Coronate (registered trademark) HL, HX, L (Nippon Urethane Polymer Co., Ltd.), P301-75E (Asahi Kasei Corporation), and the like. Commercially available isocyanurate-type trifunctional or higher isocyanates include Takenate (registered trademark) D-127N, D-170N, D-170HN, D-172N, D-177N (all Mitsui Chemicals, Inc.), Sumidur N3300, Desmodur (registered trademark) N3600, N3900, Z4470BA (all Sumika Bayer Urethane Co., Ltd.), Coronate (registered trademark) HX, HK (all Nippon Urethane Polymer Co., Ltd.), Duranate (registered trademark) TPA-100, TKA-100, TSA-100, TSS-100, TLA-100, TSE-100 (all Asahi Kasei Corporation), and the like. Commercially available biuret-type tri- or higher functional isocyanates include Takenate (registered trademark) D-165N and NP1100 (both manufactured by Mitsui Chemicals, Inc.), Desmodur (registered trademark) N3200 (manufactured by Sumika Bayer Urethane Co., Ltd.), and Duranate (registered trademark) 24A-100 (manufactured by Asahi Kasei Corporation).

[0036] At least one of the polyisocyanates may be a polyisocyanate containing a hydrophilic group. For details of polyisocyanates containing a hydrophilic group, see paragraphs

[0112] to

[0118] and

[0252] to

[0254] of WO 2016 / 052053. At least one of the polyisocyanates may be a polyisocyanate containing a polymerizable group. For details of isocyanates containing a polymerizable group, see paragraphs

[0084] to

[0089] ,

[0203] , and

[0205] of WO 2016 / 052053.

[0037] -Polyol Unit and Polyol- The urethane resin may contain at least one polyol unit. The polyol may be a polyol containing two hydroxy groups (i.e., a diol), or a polyol containing three or more hydroxy groups.

[0038] The urethane resin preferably contains a polyol unit that does not contain an acid group, from the viewpoint of further improving the retort resistance of the laminate. As the polyol unit that does not contain an acid group, a polymer polyol unit is preferred, from the viewpoint of further improving the retort resistance of the laminate. Examples of polymer polyols for forming the polymer polyol unit include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyester polyols (e.g., polyester diols), polycarbonate diols, polycaprolactone diols, etc.

[0039] The molecular weight of each of the polymer polyol unit and the polymer polyol is, for example, 500 to 10,000, preferably 800 to 5,000.

[0040] The polyol units in the urethane resin preferably contain polytetramethylene glycol units, polycarbonate diol units, or polyester polyol units, which further improves the retort resistance of the laminate.

[0041] Commercially available polymer polyols may be used to form the polymer polyol units. Commercially available polytetramethylene glycols include, for example, PTMG-2000 manufactured by Mitsubishi Chemical Corporation. Commercially available polyester polyols include, for example, P-2010 manufactured by Kuraray Co., Ltd. Commercially available polycarbonate diols include, for example, Duranol T5651 (manufactured by Asahi Kasei Corporation), Duranol T5652 (manufactured by Asahi Kasei Corporation), Duranol T6002 (manufactured by Asahi Kasei Corporation), Duranol T6001 (manufactured by Asahi Kasei Corporation), BENEBiOL HS0830B (manufactured by Mitsubishi Chemical Corporation), BENEBiOL HS0840H (manufactured by Mitsubishi Chemical Corporation), BENEBiOL NL1010DB (manufactured by Mitsubishi Chemical Corporation), and BENEBiOL NL2010DB (manufactured by Mitsubishi Chemical Corporation).

[0042] From the viewpoint of further improving pigment dispersibility and ink storage stability, the first urethane resin preferably contains a polyol unit containing an acid group (e.g., a carboxy group or a salt thereof). Examples of polyols containing an acid group include dimethylolpropionic acid (DMPA) and dimethylolbutanoic acid (DMBA). By adjusting the content of the polyol containing an acid group in the first urethane resin, the acid value of the first urethane resin and the acid value of the ink described below can be easily adjusted to preferred ranges.

[0043] From the viewpoint of further improving the retort resistance of the laminate and further improving the pigment dispersibility and storage stability of the ink, it is particularly preferable that the first urethane resin contains both a polyol unit that does not contain an acid group and a polyol unit that contains an acid group (e.g., a carboxy group or a salt thereof).

[0044] -Acid Value- The acid value of the first urethane resin is preferably 70 mgKOH / g to 180 mgKOH / g, more preferably 80 mgKOH / g to 170 mgKOH / g. When the acid value of the first urethane resin is 70 mgKOH / g or more, the dispersion stability of the pigment in the ink is further improved, and as a result, the storage stability of the ink is further improved. When the acid value of the first urethane resin is 200 mgKOH / g or less, the flexibility of the ink film (i.e., the image) is further improved, and as a result, the retort resistance of the laminate is further improved.

[0045] In the present disclosure, the acid value of the urethane resin is a value measured by neutralization titration.

[0046] The first urethane resin is preferably a water-soluble urethane resin.

[0047] In the present disclosure, "water-soluble" means the property of dissolving 1 g or more in 100 g of water at 25°C.

[0048] Glass Transition Temperature (Tg)—From the viewpoint of further improving the retort resistance of the laminate, the glass transition temperature of the first urethane resin is preferably −100° C. to 50° C., more preferably −90° C. to 30° C., even more preferably −80° C. to 15° C., and still more preferably −70° C. to 0° C.

[0049] In the present disclosure, the glass transition temperature (Tg) of the urethane resin is measured using a differential scanning calorimeter, for example, a product named "DSC-60" manufactured by Shimadzu Corporation.

[0050] Weight Average Molecular Weight The weight average molecular weight of the first urethane resin is not particularly limited, but is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and even more preferably 10,000 to 150,000.

[0051] In the present disclosure, the weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC). GPC is performed using an HLC-8220GPC (manufactured by Tosoh Corporation), with three columns connected in series: TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, and TSKgel SuperHZ2000 (all trade names manufactured by Tosoh Corporation), and THF (tetrahydrofuran) as the eluent. The conditions are a sample concentration of 0.45% by mass, a flow rate of 0.35 ml / min, a sample injection amount of 10 μl, and a measurement temperature of 40°C, and the measurement is performed using a differential refractive index detector. In addition, a calibration curve is prepared from eight samples of "Standard Sample TSK Standard, Polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0052] —Ratio of Pigment Content to First Urethane Resin Content— The ratio of the pigment content to the first urethane resin content, on a mass basis, is preferably 1:0.04 to 1:3, more preferably 1:0.05 to 1:1, and even more preferably 1:0.05 to 1:0.5.

[0053] - Content of first urethane resin relative to the total amount of ink - The content of the first urethane resin relative to the total amount of ink is preferably 0.1% by mass to 10% by mass, more preferably 0.3% by mass to 5% by mass, and even more preferably 0.5% by mass to 2.5% by mass.

[0054] Resin Particles The ink of the present disclosure contains at least one type of resin particles. The resin particles contain at least one type of second urethane resin.

[0055] The resin particles may contain at least one non-urethane resin (i.e., a resin other than a urethane resin). Examples of non-urethane resins include acrylic resins and vinyl chloride resins. However, from the viewpoint of further improving the retort resistance of the laminate, the proportion of the second urethane resin in the resin particles is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, and even more preferably 90% by mass to 100% by mass.

[0056] (Second Urethane Resin) Like the first urethane resin, the second urethane resin may be a known urethane resin (i.e., a resin containing urethane bonds). Like known urethane resins, the second urethane resin may be formed by the reaction of a polyisocyanate with a polyol. In this case, the second urethane resin may contain polyisocyanate units (i.e., structural units derived from a polyisocyanate) and polyol units (i.e., structural units derived from a polyol).

[0057] Specific examples and preferred aspects of the polyol units and polyisocyanate units (and the polyols and polyisocyanates used to form them) in the second urethane resin are the same as those of the polyol units and polyisocyanate units (and the polyols and polyisocyanates used to form them) in the first urethane resin described above. The preferred range of the weight-average molecular weight of the second urethane resin is the same as that of the first urethane resin.

[0058] However, the second urethane resin and the first urethane resin may be the same type of urethane resin or different types of urethane resin.

[0059] From the viewpoint of further improving the dispersion stability of resin particles containing this second urethane resin and the storage stability of the ink, the second urethane resin preferably contains a polyol unit containing an acid group (e.g., a carboxy group or a salt thereof). Examples of polyols containing an acid group include dimethylolpropionic acid (DMPA) and dimethylolbutanoic acid (DMBA). By adjusting the content of the polyol containing an acid group in the second urethane resin, the acid value of the second urethane resin (described later) and the acid value of the ink (described later) can be easily adjusted within preferred ranges.

[0060] -Acid Value- The acid value of the second urethane resin is preferably 5 mgKOH / g to 60 mgKOH / g, more preferably 10 mgKOH / g to 50 mgKOH / g. When the acid value of the second urethane resin is 5 mgKOH / g or more, the dispersion stability of the resin particles in the ink is further improved, and as a result, the storage stability of the ink is further improved. When the acid value of the second urethane resin is 60 mgKOH / g or less, the flexibility of the ink film (i.e., the image) is further improved, and as a result, the retort resistance of the laminate is further improved.

[0061] A preferred combination of the acid value of the first urethane resin and the acid value of the second urethane resin is, for example, a combination in which the acid value of the first urethane resin is 70 mgKOH / g to 180 mgKOH / g (more preferably 80 mgKOH / g to 170 mgKOH / g) and the acid value of the second urethane resin is 5 mgKOH / g to 60 mgKOH / g (more preferably 10 mgKOH / g to 50 mgKOH / g).

[0062] The second urethane resin is preferably a water-insoluble urethane resin.

[0063] In the present disclosure, "water-insoluble" means the property of dissolving less than 1 g in 100 g of water at 25°C.

[0064] Glass Transition Temperature (Tg) The preferred range of the glass transition temperature of the second urethane resin is the same as the preferred range of the glass transition temperature of the first urethane resin.

[0065] The absolute value of the difference between the glass transition temperature of the first urethane resin and the glass transition temperature of the second urethane resin (hereinafter also referred to as "Tg difference") is preferably not more than 50° C., more preferably not more than 40° C., even more preferably not more than 30° C., and even more preferably not more than 20° C. When the Tg difference is 50° C. or less, the uniformity and toughness of the ink film are further improved, and as a result, the retort resistance of the laminate is further improved.

[0066] - Content of second urethane resin relative to the total amount of ink - The content of the second urethane resin relative to the total amount of ink is preferably 1.0% by mass to 10.0% by mass, more preferably 2.0% by mass to 10.0% by mass, and even more preferably 2.0% by mass to 8.0% by mass.

[0067] Polyol Unit A (Common Polyol Unit) In the inks disclosed herein, it is preferable that both the first urethane resin and the second urethane resin contain, as a common polyol unit, at least one type of polyol unit that does not contain an acid group (i.e., a polyol unit that does not contain an acid group that is common to both the first urethane resin and the second urethane resin). This allows for interaction between the pigment dispersion resin containing the first urethane resin and the resin particles containing the second urethane resin, making the ink film stronger and, as a result, improving the retort resistance of the laminate. When both the first urethane resin and the second urethane resin contain polyol unit A (i.e., a polyol unit that does not contain an acid group that is common to both the first urethane resin and the second urethane resin), each of the first urethane resin and the second urethane resin may contain a polyol unit that does not contain an acid group other than polyol unit A (i.e., a polyol unit that does not contain an acid group that is not common to both the first urethane resin and the second urethane resin). Furthermore, when both the first urethane resin and the second urethane resin contain polyol units A, at least one of the first urethane resin and the second urethane resin may contain polyol units containing an acid group.

[0068] When both the first urethane resin and the second urethane resin contain polyol units A (common polyol units), the proportion of polyol units A in the polyol units not containing acid groups contained in the first urethane resin (hereinafter also referred to as the "common polyol ratio" in the first urethane resin) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more.

[0069] When both the first urethane resin and the second urethane resin contain polyol units A (common polyol units), the proportion of polyol units A in the polyol units not containing acid groups contained in the second urethane resin (hereinafter also referred to as the "common polyol ratio" in the second urethane resin) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more.

[0070] <Water-soluble organic solvent> From the viewpoint of ink ejection stability, the ink of the present disclosure preferably contains at least one water-soluble organic solvent. Here, the meaning of water-soluble is as described above.

[0071] The type of water-soluble organic solvent is not limited, and examples thereof include: monoalcohols having 1 to 4 carbon atoms; alkylene glycols (also known as diols) such as ethylene glycol, propylene glycol (also known as 1,2-propanediol), 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, and 4-methyl-1,2-pentanediol; triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane; alkylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ethers and propylene glycol monoalkyl ethers; polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, and polyoxyethylene polyoxypropylene glycol; Examples thereof include polyalkylene glycol ethers such as diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tripropylene glycol monoalkyl ether, and polyoxypropylene glyceryl ether; 2-pyrrolidone, and N-methyl-2-pyrrolidone.

[0072] In particular, from the viewpoint of ink ejection stability, the water-soluble organic solvent in the ink preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol monoalkyl ethers.

[0073] The content of the water-soluble organic solvent is preferably 10% by mass to 40% by mass, and more preferably 15% by mass to 30% by mass, based on the total amount of the ink.

[0074] <Surfactant> The ink may contain at least one surfactant. The type of surfactant is not particularly limited, and may be any of anionic surfactants, cationic surfactants, betaine surfactants, and nonionic surfactants. Examples of surfactants include acrylic surfactants, fluorine-based surfactants, and silicone-based surfactants.

[0075] The content of the surfactant is preferably 0.1% by mass to 5% by mass, and more preferably 0.2% by mass to 2% by mass, based on the total amount of the ink.

[0076] <Other Components> The ink of the present disclosure may contain other components in addition to those described above, as necessary. Examples of other components that may be contained in the ink include known additives such as water-soluble resins, colloidal silica, solid wetting agents, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, antifungal agents, pH adjusters, viscosity adjusters, rust inhibitors, and chelating agents.

[0077] <Acid Value> The ink of the present disclosure has an acid value (i.e., the acid value of the ink itself; hereinafter, also referred to as "ink acid value") of preferably 1.5 mgKOH / g to 4.5 mgKOH / g, more preferably 1.6 mgKOH / g to 4.3 mgKOH / g, and even more preferably 1.8 mgKOH / g to 4.0 mgKOH / g.

[0078] In the present disclosure, the ink acid value is a value measured by neutralization titration.

[0079] <Physical Properties> From the viewpoint of improving ejection stability, the pH (25°C) of the ink of the present disclosure is preferably 7 to 10, and more preferably 7.5 to 9.5. The pH of the ink is measured at 25°C using a pH meter, for example, a pH meter manufactured by Toa DKK Corporation (model number "HM-31")

[0080] The viscosity (30°C) of the ink of the present disclosure is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, even more preferably 2 mPa·s to 15 mPa·s, and still more preferably 3 mPa·s to 10 mPa·s. The viscosity of the ink is measured at 30°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0081] The surface tension (25°C) of the ink of the present disclosure is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 40 mN / m. The surface tension of the ink is measured at 25°C using a surface tensiometer, for example, an automatic surface tensiometer (product name "CBVP-Z" manufactured by Kyowa Interface Science Co., Ltd.) by the plate method.

[0082] [Ink Set] The ink set of the present disclosure includes the ink of the present disclosure described above and a pretreatment liquid containing water and an aggregating agent. According to the ink set of the present disclosure, the components in the ink of the present disclosure (e.g., the pigment, the first urethane resin, and the second urethane resin) can be aggregated on a non-permeable substrate by the aggregating agent in the pretreatment liquid. This further improves the image quality of the resulting image. Furthermore, because the ink set of the present disclosure includes the ink of the present disclosure described above, it achieves the same effect as that achieved by the ink of the present disclosure described above (i.e., improved retort resistance of the laminate).

[0083] The ink set of the present disclosure may include only one type of ink of the present disclosure, or may include two or more types. For example, the ink of the present disclosure may include two or more types of ink of the present disclosure that are different in hue. The ink set of the present disclosure may include one type of ink of the present disclosure and an ink other than the ink of the present disclosure. The ink set of the present disclosure may include only one type of pretreatment liquid, or may include two or more types.

[0084] <Ink> The inks of the present disclosure contained in the ink set of the present disclosure are as described above.

[0085] <Pretreatment Liquid> The pretreatment liquid included in the ink set of the present disclosure contains water and a flocculant.

[0086] (Water) The pretreatment liquid contains water. The water content is preferably 50% by mass or more, and more preferably 60% by mass or more, based on the total amount of the pretreatment liquid. The upper limit of the water content, although it depends on the amounts of other components, is preferably 90% by mass or less, and more preferably 80% by mass or less, based on the total amount of the pretreatment liquid.

[0087] (Flocculant) The pretreatment liquid of the present disclosure contains at least one flocculant. The flocculant is preferably at least one selected from the group consisting of organic acids, organic acid salts, polyvalent metal compounds, and metal complexes, more preferably at least one selected from the group consisting of organic acids, organic acid salts, and polyvalent metal compounds. Preferred flocculants include the flocculants described in paragraphs 0122 to 0130 of WO 2020 / 195360.

[0088] -Organic Acid- An organic acid is an organic compound having an acidic group. Examples of the acidic group include a phosphate group, a phosphonic acid group, a phosphinic acid group, a sulfate group, a sulfonic acid group, a sulfinic acid group, and a carboxy group. Among these, from the viewpoint of the aggregation rate of the ink, the acidic group is preferably a phosphate group or a carboxy group, and more preferably a carboxy group.

[0089] It is preferable that at least a portion of the acidic groups is dissociated in the pretreatment liquid.

[0090] Examples of organic compounds having a carboxy group include (meth)acrylic acid, poly(meth)acrylic acid, acetic acid, formic acid, benzoic acid, glycolic acid, malonic acid, malic acid (preferably DL-malic acid), maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, citric acid, tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, and nicotinic acid.

[0091] Among these, from the viewpoint of the aggregation speed of the ink, the organic compound having a carboxy group is preferably a divalent or higher carboxylic acid (hereinafter also referred to as a polycarboxylic acid), and more preferably a dicarboxylic acid.

[0092] 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.

[0093] The organic acid preferably has a low pKa (for example, 1.0 to 5.0), which reduces the surface charge of particles such as pigments and resin particles in the ink, which are stabilized by weakly acidic functional groups such as carboxyl groups, by contacting them with an organic acid having an even lower pKa, thereby lowering dispersion stability.

[0094] The organic acid preferably has a low pKa, high solubility in water, and a valence of at least 2. Furthermore, the organic acid more preferably has a high buffering capacity in a pH range lower than the pKa of the functional group (e.g., carboxy group) that stabilizes the dispersion of the particles in the ink.

[0095] -Polyvalent Metal Compound- Examples of polyvalent metal compounds include polyvalent metal salts. Examples of polyvalent metal salts include organic acid polyvalent metal salts and inorganic acid polyvalent metal salts. Preferred organic acid polyvalent metal salts are polyvalent metal salts of the above-mentioned organic acids (e.g., formic acid, acetic acid, benzoic acid, etc.). Preferred inorganic acid polyvalent metal salts are polyvalent metal nitrates, polyvalent metal hydrochlorides, or polyvalent metal thiocyanates.

[0096] Examples of polyvalent metal salts include salts of alkaline earth metals (e.g., magnesium, calcium) of Group 2 of the periodic table, salts of transition metals (e.g., lanthanum) of Group 3 of the periodic table, salts of metals (e.g., aluminum) of Group 13 of the periodic table, and salts of lanthanides (e.g., neodymium). As the polyvalent metal salt, calcium salts, magnesium salts, or aluminum salts are preferred, and calcium salts or magnesium salts are more preferred.

[0097] The polyvalent metal compound is preferably an organic acid polyvalent metal salt, more preferably an organic acid calcium salt or an organic acid magnesium salt.

[0098] It is preferable that the polyvalent metal compound is at least partially dissociated into polyvalent metal ions and counter ions in the pretreatment liquid.

[0099] The content of the flocculant in the pretreatment liquid is preferably 0.1% by mass to 40% by mass, more preferably 0.1% by mass to 30% by mass, even more preferably 1% by mass to 20% by mass, and still more preferably 1% by mass to 10% by mass, relative to the total amount of the pretreatment liquid.

[0100] (Resin) The pretreatment liquid preferably contains at least one resin, which further improves the adhesion between the ink film obtained from the ink and the pretreatment layer obtained from the pretreatment liquid, thereby further improving the retort resistance of the laminate.

[0101] The resin may be either a non-urethane resin (e.g., an acrylic resin, a vinyl chloride resin, etc.) or a urethane resin. From the viewpoint of further improving the retort resistance of the laminate, the resin in the pretreatment liquid preferably contains a urethane resin. In the present disclosure, the urethane resin that may be contained in the pretreatment liquid is referred to as a third urethane resin.

[0102] As described above, from the viewpoint of further improving the retort resistance of the laminated body, a preferred embodiment of the pretreatment liquid is an embodiment in which the pretreatment liquid contains a third urethane resin. When the pretreatment liquid contains a third urethane resin, the flexibility of the pretreatment layer (i.e., its ability to conform to an impermeable substrate) is further improved, and as a result, the retort resistance of the laminated body is further improved.

[0103] -Third Urethane Resin- Like the first urethane resin, the third urethane resin may be a known urethane resin (i.e., a resin containing urethane bonds). Like known urethane resins, the third urethane resin may be formed by the reaction of a polyisocyanate with a polyol. In this case, the second urethane resin may contain polyisocyanate units (i.e., structural units derived from a polyisocyanate) and polyol units (i.e., structural units derived from a polyol).

[0104] Specific examples and preferred aspects of the polyol units and polyisocyanate units (and the polyols and polyisocyanates used to form them) in the third urethane resin are the same as those of the polyol units and polyisocyanate units (and the polyols and polyisocyanates used to form them) in the first urethane resin described above. The preferred range of the weight-average molecular weight of the third urethane resin is the same as that of the first urethane resin.

[0105] However, the third urethane resin and the first urethane resin may be the same type of urethane resin or different types of urethane resins, and the third urethane resin and the second urethane resin may be the same type of urethane resin or different types of urethane resins.

[0106] The third urethane resin is preferably a water-insoluble urethane resin. In this case, the pretreatment liquid preferably contains resin particles containing the third urethane resin.

[0107] From the viewpoint of further improving the dispersion stability of resin particles containing this third urethane resin and the storage stability of the ink, the third urethane resin preferably contains a polyalkylene glycol monoalkyl ether unit. Examples of polyalkylene glycol monoalkyl ethers for forming the polyalkylene glycol monoalkyl ether units include polymers obtained by addition polymerization of ethylene oxide or propylene oxide with any alcohol (e.g., methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, etc.). Specific examples of polyalkylene glycol monoalkyl ethers include polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol monopropyl ether, polyethylene glycol monobutyl ether, polypropylene glycol monomethyl ether, polypropylene glycol monoethyl ether, polypropylene glycol monopropyl ether, and polypropylene glycol monobutyl ether.

[0108] The content of the polyalkylene glycol monoalkyl ether unit relative to the total amount of the third urethane resin is preferably 2% by mass to 30% by mass, more preferably 3% by mass to 25% by mass, and even more preferably 5% by mass to 20% by mass, from the viewpoint of further improving the retort resistance of the laminate.

[0109] Glass Transition Temperature (Tg) The preferred range of the glass transition temperature of the third urethane resin is the same as the preferred range of the glass transition temperature of the first urethane resin.

[0110] —Content of Third Urethane Resin Relative to Total Amount of Pretreatment Liquid— The content of the third urethane resin relative to the total amount of the pretreatment liquid is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 25% by mass, and even more preferably 3% by mass to 30% by mass.

[0111] -Polyol Unit A (Common Polyol Unit)- In the ink set of the present disclosure, it is preferable that each of the first urethane resin, the second urethane resin, and the third urethane resin contains polyol unit A, which is at least one type of polyol unit that does not contain an acid group (i.e., a polyol unit that does not contain an acid group and is common to the first urethane resin and the second urethane resin). This enables interaction between the third urethane resin in the pretreatment liquid, the pigment dispersion resin containing the first urethane resin in the ink, and the resin particles containing the second urethane resin in the ink, making the image formed by the pretreatment layer and the ink film tougher, and as a result, further improving the retort resistance of the laminate. When the first urethane resin, the second urethane resin, and the third urethane resin all contain polyol units A (i.e., "polyol units not containing acid groups" common to the first urethane resin, the second urethane resin, and the third urethane resin), each of the first urethane resin, the second urethane resin, and the third urethane resin may contain "polyol units not containing acid groups" other than the polyol units A (i.e., "polyol units not containing acid groups" not common to the first urethane resin, the second urethane resin, and the third urethane resin). Also, when the first urethane resin and the second urethane resin all contain polyol units A (i.e., "polyol units not containing acid groups" common to the first urethane resin, the second urethane resin, and the third urethane resin), at least one of the first urethane resin, the second urethane resin, and the third urethane resin may contain polyol units containing acid groups.

[0112] When the first urethane resin, the second urethane resin, and the third urethane resin all contain polyol units A (common polyol units), the proportion of polyol units A in all polyol units contained in the third urethane resin (hereinafter also referred to as the "common polyol ratio" in the third urethane resin) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more.

[0113] (Water-soluble organic solvent) The pretreatment liquid may contain at least one water-soluble organic solvent. Specific examples of the water-soluble organic solvent that may be contained in the pretreatment liquid are the same as the specific examples of the water-soluble organic solvent that may be contained in the ink.

[0114] (Surfactant) The pretreatment liquid may contain at least one surfactant. The type of surfactant is not particularly limited, and may be any of anionic surfactants, cationic surfactants, betaine surfactants, and nonionic surfactants. Examples of surfactants include acrylic surfactants, fluorine surfactants, and silicone surfactants.

[0115] The content of the surfactant is preferably 0.1 to 5% by mass, and more preferably 0.2 to 1% by mass, based on the total amount of the pretreatment liquid.

[0116] (Other Components) The pretreatment liquid may contain other components in addition to those described above, as necessary. Examples of other components that can be contained in the pretreatment liquid include the same components as those that can be contained in the ink.

[0117] (Physical Properties) The pH of the pretreatment liquid is preferably 2.0 to 7.0, and more preferably 2.0 to 4.0. The pH of the pretreatment liquid can be measured by the same method as that for the pH of the ink.

[0118] From the viewpoint of the coatability of the pretreatment liquid, the viscosity of the pretreatment liquid is preferably 0.5 mPa·s to 10 mPa·s, and more preferably 1 mPa·s to 5 mPa·s. The viscosity of the pretreatment liquid can be measured by the same method as that for the viscosity of the ink.

[0119] 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 of the pretreatment liquid can be measured by the same method as that for measuring the surface tension of the ink.

[0120] [Image Recording Method] The image recording method of the present disclosure uses the ink of the present disclosure described above and includes a step of applying the ink to an impermeable substrate by inkjet recording (hereinafter also referred to as an "ink application step"). Because the image recording method of the present disclosure uses the ink of the present disclosure described above, it achieves the same effect as the effect achieved by the ink of the present disclosure described above (i.e., improved retort resistance of the laminate).

[0121] <Non-permeable substrate> In the image recording method of the present disclosure, an image is recorded by applying the ink of the present disclosure onto a non-permeable substrate.

[0122] In the present disclosure, the term "impermeability" in an impermeable substrate refers to a property in which the water absorption rate over 24 hours measured in accordance with ASTM D570-98 (2018) is 2.5% or less. Here, the unit of water absorption rate, "%", is based on mass. The water absorption rate is preferably 1.0% or less, and more preferably 0.5% or less.

[0123] Examples of materials for the impermeable substrate include glass, metals (e.g., aluminum, zinc, copper, etc.), and resins (e.g., polyvinyl chloride, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, nylon, acrylic resin, etc.).

[0124] The material of the impermeable substrate is preferably a resin, that is, the impermeable substrate is preferably a resin substrate.

[0125] Among these, from the viewpoint of versatility, the material of the impermeable substrate is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0126] The shape of the impermeable substrate is preferably a sheet (film) or plate, and examples of such a shape of the impermeable substrate include a glass plate, a metal plate, a resin sheet (resin film), a plastic-laminated paper, a metal-laminated or metal-deposited paper, and a metal-laminated or metal-deposited plastic sheet (plastic film).

[0127] Examples of impermeable resin substrates include resin sheets (resin films), and specific examples include flexible packaging materials for packaging foods and the like, and floor guide panels in mass retailers.

[0128] Examples of impermeable substrates include not only sheet-shaped (film-shaped) or plate-shaped impermeable substrates, but also textiles (woven fabrics) and nonwoven fabrics formed from impermeable fibers.

[0129] 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.

[0130] The non-permeable substrate may be subjected to a hydrophilization treatment. Examples of hydrophilization treatments include, but are not limited to, corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, light irradiation treatment (e.g., UV treatment), and flame treatment. Corona treatment can be carried out using, for example, a Corona Master (product name "PS-10S", manufactured by Shinko Electric Meter Co., Ltd.). The conditions for the corona treatment may be appropriately selected depending on the type of non-permeable substrate, etc.

[0131] The impermeable substrate may be a transparent impermeable substrate. Here, "transparent" means that the transmittance of visible light having a wavelength of 400 nm to 700 nm is 80% or more (preferably 90% or more). When the impermeable substrate is a transparent impermeable substrate, the image is easily visible through the impermeable substrate from the non-image recording surface side of the impermeable substrate.

[0132] <Ink Application Step> The ink application step is a step of applying the ink of the present disclosure onto a non-permeable substrate by inkjet recording.

[0133] There are no particular limitations on the ink ejection method used in inkjet recording, and any of the well-known methods may be used, such as a charge control method that uses electrostatic attraction to eject ink, a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink with it, thereby ejecting the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and uses the resulting pressure.

[0134] As an inkjet recording method, in particular, the method described in JP-A-54-59936 can be effectively used, in which ink subjected to the action of thermal energy undergoes a sudden change in volume, and the ink is ejected from the nozzles by the force caused by this state change. As an inkjet recording method, the method described in paragraphs 0093 to 0105 of JP-A-2003-306623 can also be applied.

[0135] Application of ink to a non-permeable substrate by ink jet recording is carried out by ejecting the ink from the nozzles of an ink jet head.

[0136] Inkjet head methods include the shuttle method, in which a short serial head is scanned across the width of the recording medium to perform recording, and the line method, which uses a line head in which recording elements are arranged to cover the entire area of ​​one side of the recording medium.

[0137] The line method allows for image recording over the entire surface of a recording medium by scanning the recording medium in a direction intersecting the arrangement direction of the recording elements. The line method eliminates the need for a transport system, such as a carriage that scans a short head, as in the shuttle method. Furthermore, compared to the shuttle method, the line method does not require complex scanning control of the carriage movement and the recording medium, and only the recording medium moves. Therefore, the line method achieves faster image recording speeds than the shuttle method.

[0138] The ink is preferably applied using an inkjet head having a resolution of 300 dpi or more (more preferably 600 dpi or more, and even more preferably 800 dpi or more), where dpi stands for dots per inch, and 1 inch is 2.54 cm.

[0139] From the viewpoint of obtaining a high-definition image, the amount of ink droplets ejected is preferably 1 pL (picoliter) to 10 pL, and more preferably 1.5 pL to 6 pL.

[0140] (Heat Drying) The ink application step may include applying ink onto a non-permeable substrate by an inkjet recording method, and drying the applied ink by heat.

[0141] The heat drying method is not particularly limited, and examples thereof include infrared (IR) drying, hot air drying, and heat drying using a heating device (e.g., a heater, a hot plate, a heating furnace, etc.). The heat drying method may be a combination of two or more of these. Heat drying can be performed by heating the ink from at least one of the image recording side and the non-image recording side of the non-permeable substrate.

[0142] The heating temperature for drying the ink by heating is preferably 35° C. or higher, more preferably 40° C. or higher, even more preferably 50° C. or higher, and even more preferably 60° C. or higher. There is no particular upper limit to the heating temperature, but 100° C. is preferred, and 90° C. is more preferred.

[0143] The heating time for heating and drying the ink is not particularly limited, but is preferably 1 to 180 seconds, more preferably 1 to 120 seconds, and even more preferably 1 to 60 seconds.

[0144] The image recording method of the present disclosure may include, prior to the ink application step, a step of applying the pretreatment liquid described above to a surface onto which the ink is to be applied in the ink application step. In this case, one embodiment of the image recording method of the present disclosure is an embodiment in which the ink set of the present disclosure described above is used.

[0145] The image recording method according to this embodiment uses the ink set according to the present disclosure described above, and includes a pretreatment liquid applying step of applying a pretreatment liquid onto a non-permeable substrate, and an ink applying step of applying the ink according to the present disclosure onto the non-permeable substrate to which the pretreatment liquid has been applied, by an inkjet recording method.

[0146] 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.

[0147] Examples of the coating method include known coating methods using a bar coater, extrusion die coater, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, reverse roll coater, and the like.

[0148] After the pretreatment liquid is applied to the non-permeable substrate, the pretreatment liquid may be dried by heating. Examples of means for drying the pretreatment liquid by heating include known heating means such as a heater, known air blowing means such as a dryer, and a combination of these.

[0149] Examples of methods for heating and drying the pretreatment liquid include a method of applying heat using a heater or the like from the side opposite to the surface of the non-permeable substrate to which the pretreatment liquid has been applied, a method of applying warm air or hot air to the surface of the non-permeable substrate to which the pretreatment liquid has been applied, a method of applying heat using an infrared heater from the side of the non-permeable substrate to which the pretreatment liquid has been applied or the side opposite to the surface to which the pretreatment liquid has been applied, and a combination of these methods.

[0150] The heating temperature during heating and drying of the pretreatment liquid is preferably 35° C. or higher, and more preferably 40° C. or higher. There is no particular upper limit to the heating temperature, but it is preferably 100° C., more preferably 90° C., and even more preferably 70° C.

[0151] The time for heat drying 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.

[0152] [Method for manufacturing a laminated body] The method for manufacturing a laminated body of the present disclosure includes the steps of: obtaining an image recorded matter comprising an impermeable substrate and an image disposed on the impermeable substrate by the image recording method of the present disclosure described above; and laminating a laminating substrate onto the side of the image recorded matter on which the image is disposed, to obtain a laminated body.

[0153] The method for producing a laminate according to the present disclosure includes the image recording method according to the present disclosure, and therefore has the same effects as those of the image recording method according to the present disclosure. Specifically, a laminate having excellent retort resistance can be obtained.

[0154] For the step of obtaining an image recorded material, reference can be made to the image recording method of the present disclosure. The step of obtaining a laminated body is a step of laminating a laminating substrate on the side of the image recorded material on which the image is arranged to obtain a laminated body. Lamination can be performed by, for example, a method of overlapping and attaching the laminating substrate to the side on which the image is arranged of the image recorded material via another layer (e.g., an adhesive layer), or a method of overlapping and attaching the laminating substrate to the side on which the image is arranged of the image recorded material through a laminator. In the latter case, a commercially available laminator can be used.

[0155] The lamination temperature when laminating is not particularly limited. For example, when the image-recorded material and the substrate for lamination are attached via another layer (for example, an adhesive layer), the temperature may be in the range of 20°C or higher. Furthermore, when a laminator is used, the temperature of the laminating rolls may be in the range of 20°C to 80°C. The pressure between the pair of laminating rolls may be appropriately selected as needed.

[0156] The substrate for lamination is preferably a resin substrate, and is not particularly limited, but examples thereof include substrates made of thermoplastic resins.

[0157] The resin substrate may be, for example, a substrate formed by molding a thermoplastic resin into a sheet shape, and preferably contains polypropylene, polyethylene terephthalate, nylon, polyethylene, or polyimide.

[0158] The shape of the resin substrate is not particularly limited, but a sheet-like resin substrate is preferred. The thickness of the resin substrate is preferably 10 μm to 200 μm, more preferably 10 μm to 100 μm.

[0159] In the step of obtaining a laminate, the lamination substrate may be laminated directly onto the image-bearing side of the image-recorded product, or may be laminated via another layer (for example, an adhesive layer).

[0160] When the substrate for lamination is directly laminated onto the side of the image-recorded product on which the image is disposed, the lamination can be carried out by a known method such as thermocompression bonding or heat fusion bonding.

[0161] Furthermore, when laminating a substrate for lamination via an adhesive layer onto the side of an image recorded material on which an image is disposed, the lamination can be carried out, for example, by applying an adhesive to the side of the image recorded material on which the image is disposed, then placing the substrate for lamination on the side, and then bonding the image recorded material and the substrate for lamination together.

[0162] Furthermore, lamination via an adhesive layer on the image-bearing side of the image-recorded product can also be carried out by a method such as extrusion lamination (i.e., sandwich lamination).

[0163] The adhesive layer preferably contains an isocyanate. When the adhesive layer contains an isocyanate, the adhesion between the adhesive layer and the image is further improved, and therefore the retort resistance can be further improved.

[0164] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples.

[0165] Examples 1 to 25, Comparative Examples 1 to 3 Preparation of aqueous dispersions of third urethane resins (urethane resins A to F) for use in pre-treatment liquids Aqueous dispersions of each of urethane resins A to F were prepared as aqueous dispersions of third urethane resins for use in pre-treatment liquids. Each of urethane resins A to F is a specific example of a third urethane resin in the form of resin particles. Details are provided below.

[0166] (Preparation of aqueous dispersion of urethane resin A) Isophorone diisocyanate (IPDI) (14.4 g), PCD-2000 (polycarbonate diol, molecular weight 2000, manufactured by Asahi Kasei Corporation, "Duranol T5652") (87.6 g) as a polyol containing no acid groups, and ethyl acetate (80.0 g) were charged into a three-necked flask and heated to 70°C. 0.1 g of Neostan U-600 (manufactured by Nitto Kasei Corporation, inorganic bismuth catalyst; hereinafter also referred to as U-600) was added thereto and stirred at 70°C for 3 hours. Next, polyethylene glycol monomethyl ether (number average molecular weight 550) (18.0 g) was added thereto and stirred at 70°C for 3 hours. Next, isopropanol (IPA) (84.5 g) as an end-capping agent and ethyl acetate (126.5 g) were added thereto and stirred at 70°C for 7 hours. After 7 hours of stirring, the mixture was allowed to cool to room temperature, and then the concentration was adjusted using ethyl acetate to obtain a 30% by mass solution of urethane resin A (solvent: a mixed solvent of IPA and ethyl acetate). Distilled water (100 g) was added to the obtained 30% by mass solution of urethane resin A (100 g), and the mixture was emulsified at room temperature for 10 minutes using a homogenizer at 12,000 rpm (revolutions per minute) to obtain an emulsion. The obtained emulsion was heated to 50°C and stirred at 50°C for 5 hours to distill off ethyl acetate from the liquid. The liquid from which ethyl acetate had been distilled off was diluted with distilled water to a solids content of 25% by mass, thereby obtaining an aqueous dispersion of urethane resin A (solids content: 25% by mass). Urethane resin A is a third urethane resin in the form of resin particles.

[0167] (Preparation of aqueous dispersions of urethane resins B to F) Aqueous dispersions of urethane resins B to F were prepared in the same manner as in the preparation of the aqueous dispersion of urethane resin A, except that PCD-2000 used as the polyol not containing an acid group was changed to a polyol having the same molar number as shown in Tables 1 to 3.

[0168] (Explanation of Polyol) In Tables 1 to 3, "polyol" in each of the first to third urethane resins means a polyol that does not contain an acid group, and details are as follows: PTMG-2000: Polytetramethylene glycol, molecular weight 2000, manufactured by Mitsubishi Chemical Corporation. P-2010: Polyester polyol, molecular weight 2000, manufactured by Kuraray Co., Ltd. PCD-1000: Polycarbonate diol, molecular weight 1000, "Duranol T5651" manufactured by Asahi Kasei Corporation.

[0169] In Tables 1 to 3, for the third urethane resins of Examples 9 and 10, the first urethane resins of Examples 11 and 12, and the second urethane resins of Examples 13 and 14, "PCD-2000+PTMG-2000" means that PCD-2000 and PTMG-2000 were used in combination as two types of polyols not containing an acid group.

[0170] (Explanation of Common Polyol and Common Polyol Ratio (Mol %)) "Common polyol" refers to the polyol that is common to the first to third urethane resins (or common to the first urethane resin and the second urethane resin) and that serves as the base for polyol unit A, which is a polyol unit that does not contain an acid group. The "common polyol" in this group of examples (i.e., the base polyol for polyol unit A) is PCD-2000 (polycarbonate diol, molecular weight 2000). In Tables 1 to 3, "common polyol ratio (mole %)" refers to the proportion of the common polyol in all polyols used. For example, in the third urethane resins of Examples 9 and 10, the first urethane resins of Examples 11 and 12, and the second urethane resins of Examples 13 and 14, the "common polyol ratio (mole %)" refers to the proportion (mole %) of PCD-2000 (common polyol) in the total of PCD-2000 and PTMG-2000.

[0171] Preparation of Aqueous Dispersion of Non-Urethane Resin for Pretreatment Liquid; Example 25 An aqueous dispersion of vinyl chloride resin ("Viniblan 2687" manufactured by Nissin Chemical Industry Co., Ltd.) was prepared as an aqueous dispersion of non-urethane resin for pretreatment liquid.

[0172] <Preparation of Pretreatment Liquid> A pretreatment liquid having the following composition was prepared using an aqueous dispersion of a third urethane resin or an aqueous dispersion of a non-urethane resin and other components selected from the following ingredients.

[0173] - Composition of pretreatment liquid - Third urethane resin (any of urethane resins A to F) or non-urethane resin (vinyl chloride resin) listed in Tables 1 to 3... 10 mass% Glutaric acid as coagulant... 4 mass% Surfactant (product name "Olfine E1010", manufactured by Nissin Chemical Industry Co., Ltd.)... 0.5 mass% Antifoaming agent (product name "BYK-024", manufactured by BYK)... 0.01 mass% Water... balance to make up a total of 100 mass%

[0174] <Preparation of aqueous solutions of first urethane resins (pigment dispersion resins U1 to U10) for dispersing pigments in inks> Aqueous solutions of pigment dispersion resins U1 to U10 were prepared as aqueous solutions of first urethane resins for dispersing pigments in inks. Each of the pigment dispersion resins U1 to U10 is a specific example of a first urethane resin in the form of a water-soluble resin. Details are provided below.

[0175] (Preparation of aqueous solution of pigment dispersion resin U1) A three-neck flask was charged with 28.35 g of dimethylolpropionic acid (DMPA) as a polyol containing an acid group, 38.13 g of hexamethylene diisocyanate (HDI), 10.02 g of PCD-2000 (polycarbonate diol, molecular weight 2000, manufactured by Asahi Kasei Corporation, "Duranol T5652") as a polyol not containing an acid group, and 48.45 g of ethyl acetate, and the mixture was heated to 70°C. 0.1 g of Neostan U-600 (manufactured by Nitto Kasei Corporation, inorganic bismuth catalyst; hereinafter also referred to as U-600) was added thereto, and the mixture was stirred at 70°C for 7 hours. Next, 53.55 g of isopropanol (IPA) as an end-capping agent and 76.5 g of ethyl acetate were added thereto, and the mixture was stirred at 70°C for 7 hours. After stirring for 7 hours, the mixture was allowed to cool to room temperature. The concentration was then adjusted using ethyl acetate to obtain a 30% by mass solution of pigment dispersion resin U1 (solvent: a mixed solvent of IPA and ethyl acetate) as the first urethane resin. Distilled water (100 g) was added to the resulting 30% by mass solution of pigment dispersion resin U1, and aqueous sodium hydroxide solution was added while stirring. The liquid was then heated to 50°C and stirred at 50°C for 5 hours, thereby distilling off the IPA and ethyl acetate from the liquid. The liquid from which the IPA and ethyl acetate had been distilled off was diluted with distilled water to a solids content of 25% by mass, thereby obtaining an aqueous solution of pigment dispersion resin U1 (solids content 25% by mass) as the first urethane resin.

[0176] (Preparation of each aqueous solution of pigment dispersion resins U2 to U10) Aqueous solutions of pigment dispersion resins U2 to U10 were prepared in the same manner as in the preparation of the aqueous solution of pigment dispersion resin U1, except that PCD-2000 used as the polyol was changed to a polyol having the same molar number as shown in Tables 1 to 3.

[0177] In Tables 1 to 3, the polyols, common polyols, and common polyol ratios (mol %) are as described above. In Tables 1 to 3, Tg (°C) is the glass transition temperature (°C) of the corresponding resin, acid value (mg KOH / g) is the acid value (mg KOH / g) of the corresponding resin, and amount (mass %) is the content (mass %) of the corresponding resin in the entire ink.

[0178] <Preparation of Aqueous Solution of Non-Urethane Resin for Dispersing Pigment in Ink; Comparative Examples 1 and 3> An aqueous solution of acrylic resin ("Joncryl 60J" manufactured by BASF) was prepared as an aqueous solution of non-urethane resin for dispersing pigment in ink.

[0179] <Preparation of aqueous dispersions of second urethane resins (urethane resins 1 to 9) for resin particles in ink> Aqueous dispersions of each of urethane resins 1 to 9 were prepared as aqueous dispersions of second urethane resins for resin particles in ink. Each of urethane resins 1 to 9 is a specific example of a second urethane resin in the form of resin particles. Details are provided below.

[0180] (Preparation of aqueous dispersion of urethane resin 1) A three-necked flask was charged with dimethylolpropionic acid (DMPA) (3.34 g) as a polyol containing an acid group, isophorone diisocyanate (IPDI) (13.973 g), PCD-2000 (polycarbonate diol, molecular weight 2000, manufactured by Asahi Kasei Corporation, "Duranol T5652") (70.07 g) as a polyol not containing an acid group, and ethyl acetate (55.35 g), and the mixture was heated to 70°C. 0.1 g of Neostan U-600 (manufactured by Nitto Kasei Corporation, inorganic bismuth catalyst; hereinafter also referred to as U-600) was added thereto, and the mixture was stirred at 70°C for 7 hours. Next, isopropanol (IPA) (61.171 g) and ethyl acetate (87.39 g) as an end-capping agent were added thereto, and the mixture was stirred at 70°C for 7 hours. After stirring for 7 hours, the mixture was allowed to cool to room temperature. The concentration was then adjusted using ethyl acetate to obtain a 30% by weight solution of urethane resin 1 (solvent: a mixed solvent of IPA and ethyl acetate) as the second urethane resin. Distilled water (100 g) was added to the obtained 30% by weight solution of urethane resin 1, and aqueous sodium hydroxide was added while stirring. The mixture was then emulsified at room temperature for 10 minutes at 12,000 rpm using a homogenizer to obtain an emulsion. The resulting emulsion was heated to 50°C and stirred at 50°C for 5 hours, thereby distilling off the IPA and ethyl acetate from the liquid. The liquid from which the IPA and ethyl acetate had been distilled off was diluted with distilled water to a solids content of 25% by weight, thereby obtaining an aqueous dispersion of urethane resin 1 (solids content: 25% by weight) as the second urethane resin.

[0181] (Preparation of Aqueous Solutions of Urethane Resins 2 to 9) Aqueous solutions of Urethane Resins 2 to 9 were prepared in the same manner as in the preparation of the aqueous solution of Urethane Resin 1, except that PCD-2000 used as the polyol not containing an acid group was changed to a polyol having the same molar number as shown in Tables 1 to 3.

[0182] <Preparation of aqueous dispersions of non-urethane resins for use in ink> As aqueous dispersions of non-urethane resins for use in ink, an aqueous dispersion of acrylic resin ("Neocryl A-1094" manufactured by Cavestro) and an aqueous dispersion of vinyl chloride resin ("Vinyblan 701" manufactured by Nissin Chemical Industry Co., Ltd.) were prepared.

[0183] <Preparation of Magenta Pigment Dispersion> A magenta pigment dispersion was prepared using the above-described aqueous solution of the pigment dispersion resin (specifically, an aqueous solution of the first urethane resin or a non-urethane resin) and a magenta pigment (C.I. Pigment Red 122; manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) as follows. A mixture was obtained by mixing 30 parts by mass of the magenta pigment, 40 parts by mass of the above-described aqueous solution of the pigment dispersion resin (solid content 25% by mass), 115 parts by mass of water, and 15 parts by mass of propylene glycol. The mixture was subjected to a dispersion treatment at 2,500 rpm for 3 hours using a bead mill (zirconia beads with a bead diameter of 0.1 mm). This resulted in a magenta pigment dispersion with a magenta pigment solid content concentration of 15% by mass.

[0184] <Preparation of ink> An ink having the following composition was prepared using the above-described magenta pigment dispersion, the above-described aqueous dispersion of resin particles (specifically, the above-described aqueous dispersion of the second urethane resin or the aqueous dispersion of a non-urethane resin), and other components selected from the following components.

[0185] - Ink composition - Magenta pigment... 3 mass % Pigment dispersion resin (first urethane resin or non-urethane resin listed in Tables 1 to 3)... amount (mass %) listed in Tables 1 to 3 Water-soluble organic solvent (propylene glycol)... 20 mass % Water-soluble organic solvent (propylene glycol monomethyl ether)... 1 mass % Surfactant (product name "Surfynol 2502", manufactured by Nissin Chemical Industry Co., Ltd.)... 1 mass % Surfactant (product name "BYK-349", manufactured by BYK)... 0.5 mass % Water-soluble resin: polyvinylpyrrolidone (product name "PVP K-15", manufactured by ASHLAND)... 0.1 mass % Resin particles (second urethane resin or non-urethane resin listed in Tables 1 to 3)... amount (mass %) listed in Tables 1 to 3 Water... balance to make the total 100 mass %

[0186] In Tables 1 to 3, the ink acid value (mg KOH / g) is the acid value (mg KOH / g) of the entire ink, the Tg difference (°C) is the absolute value of the difference between the glass transition temperature (°C) of the first urethane resin and the glass transition temperature (°C) of the second urethane resin, and the urethane resin ratio (mass %) is the ratio (mass %) of the urethane resin to the total resin components contained in the ink.

[0187] <Image Recording> Image recording was performed using the pretreatment liquid and ink. An inkjet recording apparatus was prepared, which included a conveying system for continuously conveying a long substrate, a wire bar coater for applying the pretreatment liquid to the substrate, and an inkjet head for applying the ink. Furthermore, a non-permeable polyethylene terephthalate (PET) substrate ("FE2001" manufactured by Futamura Chemical Co., Ltd., 12 μm thick, 780 mm wide, and 4000 m long; hereinafter referred to as "non-permeable substrate A") was prepared as the substrate.

[0188] The above pretreatment liquid was applied to the non-permeable substrate A at a rate of about 1.7 g / m using a wire bar coater. ２The ink was applied so that the thickness of the pretreatment liquid was 100 μm, and then dried at 50° C. for 2 seconds. Using an inkjet recording device, while continuously transporting the non-permeable substrate A at 50 m / min, ink was ejected from an inkjet head to apply a solid image to the surface of the non-permeable substrate A that had been coated with the pretreatment liquid. The applied ink was dried with hot air at 80° C. for 30 seconds to record a solid image, and an image recording was obtained.

[0189] - Ink application conditions - Inkjet head: 1200 dpi / 30 inch wide piezo full line head Amount of ink ejected from inkjet head: 3.0 pL (picoliters) Driving frequency: 41 kHz (substrate conveying speed: 50 m / min)

[0190] [Evaluation] The following evaluations were carried out for each of the Examples and Comparative Examples. The results are shown in Tables 1 to 3.

[0191] (Retort resistance of laminated body) Using a dry laminating machine (product name "FL2", manufactured by Fuji Machine Industry Co., Ltd.), a dry laminating adhesive (main agent LX-500 (polyester urethane polyol) / curing agent KR-90S (polyisocyanate); manufactured by DIC Corporation) was applied onto the solid image of the image recorded material, and an unstretched polypropylene film (product name "FRTK-G", manufactured by Futamura Chemical Co., Ltd., thickness 60 μm) was layered thereon as a laminating substrate. In this state, the laminating substrate and the image recorded material were bonded together to obtain a laminated body.

[0192] The resulting laminate was aged at 40°C for 72 hours. Two sample pieces, each 200 mm long and 200 mm wide, were cut out from the aged laminate. The cut-out sample pieces were overlapped and heat-sealed on three sides to obtain a bag. The resulting bag was filled with pure water and then heat-sealed.

[0193] The sealed bag was placed in an autoclave (small sterilizer) for retort foods (product name "SR-240", manufactured by Tommy Seiko Co., Ltd.) and subjected to a heat and pressure sterilization treatment (i.e., retort treatment) at 120°C for 10 minutes. After the retort treatment, the bag was removed and the condition of the bag was visually observed. Specifically, the retort resistance was evaluated based on the deformation of the bag and the presence or absence of laminate lifting. The evaluation criteria are as follows. Laminate lifting refers to a state in which lifting occurs due to peeling of the image or laminate substrate.

[0194] - Evaluation criteria for retort resistance of laminate - 5: No deformation or laminate lifting was observed. 4: No laminate lifting, but deformation was observed. 3: Laminate lifting was observed in one location. 2: Laminate lifting was observed in multiple locations. 1: Laminate lifting was observed over the entire surface of the sample piece.

[0195] (Storage Stability) The viscosity of the ink prepared and allowed to stand at 25°C for 1 hour (hereinafter referred to as "viscosity before storage") and the viscosity of the ink prepared and stored in a sealed state at 60°C for 14 days (hereinafter referred to as "viscosity after storage") were measured. Both the viscosity before storage and the viscosity after storage were measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYO CO., LTD.) at 30°C and 100 rpm (revolutions per minute). Here, a sealed state refers to a state in which the contents are sealed in a container and the mass of the contents decreases by less than 1% by mass when stored at 50°C for 14 days. The viscosity increase was calculated by subtracting the viscosity before storage from the viscosity after storage. The smaller the viscosity increase, the better the storage stability. The evaluation criteria are as follows: 5: The viscosity increase was less than 0.3 mPa·s. 4: The viscosity increase was 0.3 mPa·s or more and less than 0.5 mPa·s. 3: The viscosity increase was 0.5 mPa·s or more and less than 1.0 mPa·s. 2: The viscosity increase was 1.0 mPa·s or more and less than 2.0 mPa·s. 1: The viscosity increase was 2.0 mPa·s or more.

[0196]

[0197]

[0198]

[0199] As shown in Tables 1 to 3, in each example using an ink containing water, pigment, pigment dispersion resin, and resin particles, where the pigment dispersion resin contained a first urethane resin and the resin particles contained a second urethane resin, the retort resistance of the laminated body was excellent and the storage stability of the ink was also excellent. In contrast, in Comparative Examples 1 and 3, where the pigment dispersion resin contained an acrylic resin instead of a urethane resin, and Comparative Example 2, where the resin particles contained an acrylic resin instead of a urethane resin, the retort resistance of the laminated body was insufficient.

[0200] The results of Examples 2 to 5 show that when the ratio of urethane resin to the total resin components contained is 80 mass % or more (Examples 2 and 4), the retort resistance of the laminate is further improved.

[0201] The results of Examples 1, 6, 7, and 8 show that when both the first urethane resin and the second urethane resin contain polyol unit A (i.e., a common polyol unit), which is at least one type of polyol unit that does not contain an acid group (Examples 1 and 6), the retort resistance of the laminate is further improved.

[0202] The results of Examples 11 and 12 show that when the common polyol ratio in the first urethane resin (i.e., the proportion of polyol units A (i.e., common polyol units) among all polyol units contained in the first urethane resin) is 60 mol% or more (Example 11), the retort resistance of the laminate is further improved.

[0203] The results of Examples 13 and 14 show that when the common polyol ratio in the second urethane resin (i.e., the proportion of polyol units A (i.e., common polyol units) among all polyol units contained in the second urethane resin) is 60 mol% or more (Example 13), the retort resistance of the laminate is further improved.

[0204] The results of Examples 1, 17, and 18 show that when the Tg difference (i.e., the absolute value of the difference between the glass transition temperature of the first urethane resin and the glass transition temperature of the second urethane resin) is 40°C or less (Example 1), the retort resistance of the laminate is further improved.

[0205] The results of Examples 19 to 21 show that when the acid value of the first urethane resin is 80 mgKOH / g to 170 mgKOH / g (Example 20), the retort resistance of the laminate is further improved.

[0206] The results of Examples 22 to 24 show that when the acid value of the second urethane resin is 10 mgKOH / g to 50 mgKOH / g (Example 23), the retort resistance of the laminate is further improved.

[0207] The results of Examples 19 and 20 show that when the acid value of the ink is 1.8 mgKOH / g or more (Example 20), the retort resistance of the laminate and the storage stability of the ink are further improved.The results of Examples 23 and 24 show that when the acid value of the ink is 4.0 mgKOH / g or less (Example 23), the retort resistance of the laminate is further improved.

[0208] The results of Examples 20, 21, and 25 show that when the pretreatment liquid contains a third urethane resin (Examples 20 and 21), the retort resistance of the laminate is further improved.

[0209] The results of Examples 1 and 6 show that when the first urethane resin, the second urethane resin, and the third urethane resin all contain polyol unit A (i.e., a common polyol unit), which is at least one type of polyol unit that does not contain an acid group (Example 1), the retort resistance of the laminate is further improved.

[0210] The results of Examples 9 and 10 show that when the common polyol ratio in the third urethane resin (i.e., the proportion of polyol units A (i.e., common polyol units) among all polyol units contained in the third urethane resin) is 60 mol% or more (Example 9), the retort resistance of the laminate is further improved.

[0211] Examples 101 to 105, 111 to 114, and 117 to 124: In Examples 1 to 5, 11 to 14, and 17 to 24, which used a common pretreatment liquid, the same operations as in Examples 1 to 5, 11 to 14, and 17 to 24 were carried out, except that the application of the pretreatment liquid was omitted (Examples 101 to 105, 111 to 114, and 117 to 124). As a result, in Examples 101 to 105, 111 to 114, and 117 to 124, the retort resistance of the laminated body obtained was similar to that of Examples 1 to 5, 11 to 14, and 17 to 24. This confirmed that the application of a pretreatment liquid did not affect the retort resistance of the laminated body.

[0212] The disclosure of Japanese Patent Application No. 2023-095065, filed on June 8, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. The ink contains water, a pigment, a pigment dispersion resin, and resin particles, the pigment dispersion resin containing a first urethane resin, and the resin particles containing a second urethane resin; The second urethane resin has a glass transition temperature of −90° C. to 30° C. Inkjet ink for non-porous substrates.

2. 2. The inkjet ink for non-permeable substrates according to claim 1, wherein the proportion of the urethane resin in the total resin components contained is 80% by mass or more.

3. Both the first urethane resin and the second urethane resin contain polyol units A which are at least one type of polyol units not containing an acid group. The ink-jet ink for non-permeable substrates according to claim 1 .

4. The inkjet ink for non-penetrable substrates according to claim 3 , wherein the proportion of the polyol units A in the polyol units not containing an acid group contained in the first urethane resin is 60 mol % or more.

5. The inkjet ink for non-penetrable substrates according to claim 3 , wherein the proportion of the polyol units A in the polyol units not containing an acid group contained in the second urethane resin is 60 mol % or more.

6. The inkjet ink for non-permeable substrates according to claim 1 , wherein the absolute value of the difference between the glass transition temperature of the first urethane resin and the glass transition temperature of the second urethane resin is 40° C. or less.

7. the acid value of the first urethane resin is 80 mgKOH / g to 170 mgKOH / g; The acid value of the second urethane resin is 10 mgKOH / g to 50 mgKOH / g. The ink-jet ink for non-permeable substrates according to claim 1 .

8. 2. The ink-jet ink for non-permeable substrates according to claim 1, wherein the acid value is from 1.8 mg KOH / g to 4.0 mg KOH / g.

9. The inkjet ink for non-permeable substrates according to any one of claims 1 to 8, a pretreatment liquid containing water and a flocculant; Including, an ink set.

10. The ink set according to claim 9 , wherein the pretreatment liquid further contains a third urethane resin.

11. Each of the first urethane resin, the second urethane resin, and the third urethane resin contains a polyol unit A which is at least one kind of polyol unit not containing an acid group. The ink set according to claim 10.

12. 12. The ink set according to claim 11, wherein the proportion of the polyol units A in the polyol units not containing an acid group contained in the third urethane resin is 60 mol % or more.

13. The inkjet ink for non-permeable substrates according to any one of claims 1 to 8 is used, applying the inkjet ink for non-permeable substrates onto a non-permeable substrate by an inkjet recording method; Image recording method.

14. The ink set according to claim 9 is used, applying the pretreatment liquid onto an impermeable substrate; applying the inkjet ink for non-permeable substrates by an inkjet recording method onto the non-permeable substrate to which the pretreatment liquid has been applied; An image recording method comprising:

15. A step of obtaining an image recorded matter comprising the impermeable substrate and an image disposed on the impermeable substrate by the image recording method according to claim 13; a step of laminating a substrate for lamination onto the side of the image-recorded product on which the image is arranged to obtain a laminate; A method for producing a laminate comprising the steps of: